Science.gov

Sample records for active input current

  1. Input-current shaped ac to dc converters

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The problem of achieving near unity power factor while supplying power to a dc load from a single phase ac source of power is examined. Power processors for this application must perform three functions: input current shaping, energy storage, and output voltage regulation. The methods available for performing each of these three functions are reviewed. Input current shaping methods are either active or passive, with the active methods divided into buck-like and boost-like techniques. In addition to large reactances, energy storage methods include resonant filters, active filters, and active storage schemes. Fast voltage regulation can be achieved by post regulation or by supplementing the current shaping topology with an extra switch. Some indications of which methods are best suited for particular applications concludes the discussion.

  2. Input current shaped ac-to-dc converters

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Input current shaping techniques for ac-to-dc converters were investigated. Input frequencies much higher than normal, up to 20 kHz were emphasized. Several methods of shaping the input current waveform in ac-to-dc converters were reviewed. The simplest method is the LC filter following the rectifier. The next simplest method is the resistor emulation approach in which the inductor size is determined by the converter switching frequency and not by the line input frequency. Other methods require complicated switch drive algorithms to construct the input current waveshape. For a high-frequency line input, on the order of 20 kHz, the simple LC cannot be discarded so peremptorily, since the inductor size can be compared with that for the resistor emulation method. In fact, since a dc regulator will normally be required after the filter anyway, the total component count is almost the same as for the resistor emulation method, in which the filter is effectively incorporated into the regulator.

  3. AC-DC converter with an improved input current waveform

    SciTech Connect

    Yuvarajan, S.; Weng, D.F.; Chen, M.S.

    1995-12-31

    The paper proposes a new control scheme for an ac-dc converter that will reduce the total harmonic distortion in the input current while operating at an improved power factor. The circuit uses a diode rectifier whose output is varied by a boost regulator with a second-harmonic injected PWM. An approximate analysis shows that the addition of a second harmonic component in the PWM helps to reduce the third harmonic in the input current. The design parameters are obtained using digital simulation. The results obtained on an experimental converter are compared with the ones obtained from a conventional scheme.

  4. A Josephson current-injection three-input AND gate

    SciTech Connect

    Akahori, Y.; Hohkawa, K.

    1987-02-01

    A new current-injection-type Josephson three-input AND gate is analyzed. This AND gate is experimentally fabricated by standard Pb alloy technology and then successfully operated. It is composed of three resistor-coupled logics (RCL's) and two resistors placed between the RCL gate-current terminals in series. In this circuit, only one RLC is powered by a regulator and the others are powered with the RCL output current of the first RCL through the contact resistors. This circuit configuration offers advantages of low power dissipation and source-resistance area reduction.

  5. RF Input Power Couplers for High Current SRF Applications

    SciTech Connect

    Khan, V. F.; Anders, W.; Burrill, Andrew; Knobloch, Jens; Kugeler, Oliver; Neumann, Axel; Wang, Haipeng

    2014-12-01

    High current SRF technology is being explored in present day accelerator science. The bERLinPro project is presently being built at HZB to address the challenges involved in high current SRF machines with the goal of generating and accelerating a 100 mA electron beam to 50 MeV in continuous wave (cw) mode at 1.3 GHz. One of the main challenges in this project is that of handling the high input RF power required for the photo-injector as well as booster cavities where there is no energy recovery process. A high power co-axial input power coupler is being developed to be used for the photo-injector and booster cavities at the nominal beam current. The coupler is based on the KEK–cERL design and has been modified to minimise the penetration of the coupler tip in the beam pipe without compromising on beam-power coupling (Qext ~105). Herein we report on the RF design of the high power (115 kW per coupler, dual couplers per cavity) bERLinPro (BP) coupler along with initial results on thermal calculations. We summarise the RF conditioning of the TTF-III couplers (modified for cw operation) performed in the past at BESSY/HZB. A similar conditioning is envisaged in the near future for the low current SRF photo-injector and the bERLinPro main linac cryomodule.

  6. Operation of the MPD thruster with stepped current input

    SciTech Connect

    Barnett, J.W.

    1985-01-01

    A magnetoplasmadynamic (MPD) thruster was operated with stepped current pulses in order to investigate the sensitivity of its operation to non-constant current input. The thruster terminal voltage is found to lag the current increment by increasing times as the highest level of the stepped current pulse nears the onset condition. Magnetic field transients corresponding to the terminal voltage transients appear in the thruster exhaust. The magnetic field and terminal voltage equilibrations can be interpreted in terms of magnetic diffusion and convection processes. The time constants of equilibration are largest in the exhaust portion of the discharge, where the discharge scale length is much larger than in the thrust chamber. The transient thrust following a current step up is estimated to be below the quasi steady thrust, while the transient thrust following a current step down is estimated to be above the quasi steady thrust. When the thruster is powered with a current step up whose upper plateau is near the onset conditions, the prolonged discharge transient allows a diagnostic look at the development on the onset condition. Electric field probing for different propellant injection geometries suggest that the larger terminal voltages associated with operation near onset may result from two distinct processes: an increasing anode fall, probably caused by insufficient propellant near the anode, or the back emf of the plasma flow.

  7. The domain of neuronal firing on a plane of input current and conductance.

    PubMed

    Smirnova, E Yu; Zaitsev, A V; Kim, K Kh; Chizhov, A V

    2015-10-01

    The activation of neurotransmitter receptors increases the current flow and membrane conductance and thus controls the firing rate of a neuron. In the present work, we justified the two-dimensional representation of a neuronal input by voltage-independent current and conductance and obtained experimentally and numerically a complete input-output (I/O) function. The dependence of the steady-state firing rate on the input current and conductance was studied as a two-parameter I/O function. We employed the dynamic patch clamp technique in slices to get this dependence for the whole domain of two input signals that evoke stationary spike trains in a single neuron (Ω-domain). As found, the Ω-domain is finite and an additional conductance decreases the range of spike-evoking currents. The I/O function has been reproduced in a Hodgkin-Huxley-like model. Among the simulated effects of different factors on the I/O function, including passive and active membrane properties, external conditions and input signal properties, the most interesting were: the shift of the right boundary of the Ω-domain (corresponding to the exCitation block) leftwards due to the decrease of the maximal potassium conductance; and the reduction of the Ω-domain by the decrease of the maximal sodium concentration. As found in experiments and simulations, the Ω-domain is reduced by the decrease of extracellular sodium concentration, by cooling, and by adding slow potassium currents providing interspike interval adaptation; the Ω-domain height is increased by adding color noise. Our modeling data provided a generalization of I/O dependencies that is consistent with previous studies and our experiments. Our results suggest that both current flow and membrane conductance should be taken into account when determining neuronal firing activity. PMID:26278407

  8. Somatosensory Anticipatory Alpha Activity Increases to Suppress Distracting Input

    ERIC Educational Resources Information Center

    Haegens, Saskia; Luther, Lisa; Jensen, Ole

    2012-01-01

    Effective processing of sensory input in daily life requires attentional selection and amplification of relevant input and, just as importantly, attenuation of irrelevant information. It has been proposed that top-down modulation of oscillatory alpha band activity (8-14 Hz) serves to allocate resources to various regions, depending on task…

  9. Characteristics of AZO thin films prepared at various Al target input current deposited on PET substrate

    NASA Astrophysics Data System (ADS)

    Kim, Yun-Hae; Park, Chang-Wook; Lee, Jin-Woo; Lee, Dong Myung

    2015-03-01

    Transparent conductive oxide is a thin film to be used in numerous applications throughout the industry in general. Transparent electrode materials used in these industries are in need of light transmittance with excellent high and low electrical characteristics, substances showing the most excellent physical properties while satisfying all the characteristics such as indium tin oxide film. However, reserves of indium are very small, there is an environmental pollution problem. So the study of zinc oxide (ZnO) is actively carried out in an alternative material. This study analyzed the characteristics by using a direct current (DC) magnetron sputtering system. The electric and optical properties of these films were studied by Hall measurement and optical spectroscopy, respectively. When the Al target input current is 2 mA and 4 mA, it demonstrates about 80% transmittance in the range of the visible spectrum. Also, when Al target input current was 6 mA, sheet resistance was the smallest on PET substrate. The minimum resistivity is 3.96×10-3 ohm/sq.

  10. New continuous-input current charge pump power-factor-correction electronic ballast

    SciTech Connect

    Qian, J.; Lee, F.C.; Yamauchi, Tokushi

    1999-03-01

    Continuous-input current charge pump power-factor-correction (CIC-CPPFC) electronic ballasts are proposed in this paper. The CPPFC circuit and unity power factor condition using the charge pump concept are derived and analyzed. The average lamp current control with switching frequency modulation was developed so that the low crest factor and constant lamp power operation can be achieved. The developed electronic ballast has continuous input current, so that a small line input filter can be used. The proposed CIC-CPPFC electronic ballast was implemented and tested with two 45-W fluorescent lamps. It is shown that the measured line input current harmonics satisfy IEC 1000-3-2 Class C requirements.

  11. Amplifier spurious input current components in electrode-electrolyte interface impedance measurements

    PubMed Central

    Felice, Carmelo J; Madrid, Rossana E; Valentinuzzi, Max E

    2005-01-01

    Background In Impedance Microbiology, the time during which the measuring equipment is connected to the bipolar cells is rather long, usually between 6 to 24 hrs for microorganisms with duplication times in the order of less than one hour and concentrations ranging from 101 to 107 [CFU/ml]. Under these conditions, the electrode-electrolyte interface impedance may show a slow drift of about 2%/hr. By and large, growth curves superimposed on such drift do not stabilize, are less reproducible, and keep on distorting all over the measurement of the temporal reactive or resistive records due to interface changes, in turn originated in bacterial activity. This problem has been found when growth curves were obtained by means of impedance analyzers or with impedance bridges using different types of operational amplifiers. Methods Suspecting that the input circuitry was the culprit of the deleterious effect, we used for that matter (a) ultra-low bias current amplifiers, (b) isolating relays for the selection of cells, and (c) a shorter connection time, so that the relays were maintained opened after the readings, to bring down such spurious drift to a negligible value. Bacterial growth curves were obtained in order to test their quality. Results It was demonstrated that the drift decreases ten fold when the circuit remained connected to the cell for a short time between measurements, so that the distortion became truly negligible. Improvement due to better-input amplifiers was not as good as by reducing the connection time. Moreover, temperature effects were insignificant with a regulation of ± 0.2 [°C]. Frequency did not influence either. Conclusion The drift originated either at the dc input bias offset current (Ios) of the integrated circuits, or in discrete transistors connected directly to the electrodes immersed in the cells, depending on the particular circuit arrangement. Reduction of the connection time was the best countermeasure. PMID:15796776

  12. Effects of Age of English Exposure, Current Input/Output, and grade on bilingual language performance.

    PubMed

    Bedore, Lisa M; Peña, Elizabeth D; Griffin, Zenzi M; Hixon, J Gregory

    2016-05-01

    This study evaluates the effects of Age of Exposure to English (AoEE) and Current Input/Output on language performance in a cross-sectional sample of Spanish-English bilingual children. First- (N = 586) and third-graders (N = 298) who spanned a wide range of bilingual language experience participated. Parents and teachers provided information about English and Spanish language use. Short tests of semantic and morphosyntactic development in Spanish and English were used to quantify children's knowledge of each language. There were significant interactions between AoEE and Current Input/Output for children at third grade in English and in both grades for Spanish. In English, the relationship between AoEE and language scores were linear for first- and third-graders. In Spanish a nonlinear relationship was observed. We discuss how much of the variance was accounted for by AoEE and Current Input/Output. PMID:26916066

  13. Critical carbon input to maintain current soil organic carbon stocks in global wheat systems.

    PubMed

    Wang, Guocheng; Luo, Zhongkui; Han, Pengfei; Chen, Huansheng; Xu, Jingjing

    2016-01-01

    Soil organic carbon (SOC) dynamics in croplands is a crucial component of global carbon (C) cycle. Depending on local environmental conditions and management practices, typical C input is generally required to reduce or reverse C loss in agricultural soils. No studies have quantified the critical C input for maintaining SOC at global scale with high resolution. Such information will provide a baseline map for assessing soil C dynamics under potential changes in management practices and climate, and thus enable development of management strategies to reduce C footprint from farm to regional scales. We used the soil C model RothC to simulate the critical C input rates needed to maintain existing soil C level at 0.1° × 0.1° resolution in global wheat systems. On average, the critical C input was estimated to be 2.0 Mg C ha(-1) yr(-1), with large spatial variability depending on local soil and climatic conditions. Higher C inputs are required in wheat system of central United States and western Europe, mainly due to the higher current soil C stocks present in these regions. The critical C input could be effectively estimated using a summary model driven by current SOC level, mean annual temperature, precipitation, and soil clay content. PMID:26759192

  14. Critical carbon input to maintain current soil organic carbon stocks in global wheat systems

    NASA Astrophysics Data System (ADS)

    Wang, Guocheng; Luo, Zhongkui; Han, Pengfei; Chen, Huansheng; Xu, Jingjing

    2016-01-01

    Soil organic carbon (SOC) dynamics in croplands is a crucial component of global carbon (C) cycle. Depending on local environmental conditions and management practices, typical C input is generally required to reduce or reverse C loss in agricultural soils. No studies have quantified the critical C input for maintaining SOC at global scale with high resolution. Such information will provide a baseline map for assessing soil C dynamics under potential changes in management practices and climate, and thus enable development of management strategies to reduce C footprint from farm to regional scales. We used the soil C model RothC to simulate the critical C input rates needed to maintain existing soil C level at 0.1° × 0.1° resolution in global wheat systems. On average, the critical C input was estimated to be 2.0 Mg C ha-1 yr-1, with large spatial variability depending on local soil and climatic conditions. Higher C inputs are required in wheat system of central United States and western Europe, mainly due to the higher current soil C stocks present in these regions. The critical C input could be effectively estimated using a summary model driven by current SOC level, mean annual temperature, precipitation, and soil clay content.

  15. Critical carbon input to maintain current soil organic carbon stocks in global wheat systems

    PubMed Central

    Wang, Guocheng; Luo, Zhongkui; Han, Pengfei; Chen, Huansheng; Xu, Jingjing

    2016-01-01

    Soil organic carbon (SOC) dynamics in croplands is a crucial component of global carbon (C) cycle. Depending on local environmental conditions and management practices, typical C input is generally required to reduce or reverse C loss in agricultural soils. No studies have quantified the critical C input for maintaining SOC at global scale with high resolution. Such information will provide a baseline map for assessing soil C dynamics under potential changes in management practices and climate, and thus enable development of management strategies to reduce C footprint from farm to regional scales. We used the soil C model RothC to simulate the critical C input rates needed to maintain existing soil C level at 0.1° × 0.1° resolution in global wheat systems. On average, the critical C input was estimated to be 2.0 Mg C ha−1 yr−1, with large spatial variability depending on local soil and climatic conditions. Higher C inputs are required in wheat system of central United States and western Europe, mainly due to the higher current soil C stocks present in these regions. The critical C input could be effectively estimated using a summary model driven by current SOC level, mean annual temperature, precipitation, and soil clay content. PMID:26759192

  16. Effects of Age of English Exposure, Current Input/Output, and Grade on Bilingual Language Performance

    ERIC Educational Resources Information Center

    Bedore, Lisa M.; Pena, Elizabeth D.; Griffin, Zenzi M.; Hixon, J. Gregory

    2016-01-01

    This study evaluates the effects of Age of Exposure to English (AoEE) and Current Input/Output on language performance in a cross-sectional sample of Spanish-English bilingual children. First- (N = 586) and third-graders (N = 298) who spanned a wide range of bilingual language experience participated. Parents and teachers provided information…

  17. Modifications of the input currents on VTA dopamine neurons following acute versus chronic cocaine exposure.

    PubMed

    Michaeli, Avner; Matzner, Henry; Poltyrev, Tatyana; Yaka, Rami

    2012-03-01

    Excitatory synapses on dopamine (DA) neurons in the ventral tegmental area (VTA) are modulated following exposure to various addictive drugs, including cocaine. Previously we have shown that cocaine affects GABA(A) receptor (GABA(A)R)-mediated neurotransmission in VTA DA neurons. This finding led us to reexamine the modulation of the excitatory synapse on these neurons in response to cocaine exposure, while the activity of GABA(A)R is uninterrupted. Using rat brain slices, evoked post synaptic currents (ePSC) were monitored and inhibitors of NMDA receptor (NMDAR) and AMPA receptor (AMPAR) were gradually added to inhibitors-free bath solution. Modifications in the efficacy of the excitatory synapses were evaluated by comparing AMPAR-mediated and NMDAR-mediated currents (AMPA/NMDA ratio). The lack of GABA(A)R inhibitors enabled us to examine parallel changes in the relation between GABA(A)R-mediated and NMDAR-mediated currents (GABA(A)/NMDA ratio). First, we found that AMPA/NMDA ratio measured under complete availability of GABA(A)R, is significantly higher than the ratio measured under GABA(A)R blockade. In addition, GABA(A)/NMDA ratio, but not AMPA/NMDA ratio, is augmented a few hours following in vitro acute cocaine exposure. When measured 24 h after in vivo single cocaine injection, no change in GABA(A)/NMDA ratio was observed, however, the AMPA/NMDA ratio was found to be significantly higher. Finally, a decrease in both ratios was detected in rats repeatedly injected with cocaine. Taken together, these results lead to a better understanding of the means by which cocaine modifies synaptic inputs on VTA DA neurons. The parallel changes in GABA(A)/NMDA ratio may suggest an interaction between inhibitory and excitatory neural systems. PMID:22197515

  18. The effect of a dielectric cover on the current distribution and input impedance of printed dipoles

    NASA Astrophysics Data System (ADS)

    Soares, A. J. M.; Giarola, A. J.; Barrosa de Assis Fonseca, S.

    1984-11-01

    The effect of the thickness and relative permittivity of a dielectric cover on a printed microstrip dipole has been analyzed. It is shown that the current distribution and the input impedance are, in general, very sensitive to variations of the cover parameters. For a dielectric plate with a constant thickness the dipole resonant length decreases substantially with an increase of the relative permittivity. Because of the limited bandwidth presented by single-element microstrip antennas the effects of the dielectric cover on the design of these antennas have to be carefully considered. For the calculation of the current distribution, the Hertz vector potential associated with the problem was determined for an element of current located in a stratified medium with four layers. Pocklington's integral equation was solved for the currents, using Galerkin's method with piecewise-sinusoidal expansion and weighting functions.

  19. Subthreshold membrane currents confer distinct tuning properties that enable neurons to encode the integral or derivative of their input

    PubMed Central

    Ratté, Stéphanie; Lankarany, Milad; Rho, Young-Ah; Patterson, Adam; Prescott, Steven A.

    2015-01-01

    Neurons rely on action potentials, or spikes, to encode information. But spikes can encode different stimulus features in different neurons. We show here through simulations and experiments how neurons encode the integral or derivative of their input based on the distinct tuning properties conferred upon them by subthreshold currents. Slow-activating subthreshold inward (depolarizing) current mediates positive feedback control of subthreshold voltage, sustaining depolarization and allowing the neuron to spike on the basis of its integrated stimulus waveform. Slow-activating subthreshold outward (hyperpolarizing) current mediates negative feedback control of subthreshold voltage, truncating depolarization and forcing the neuron to spike on the basis of its differentiated stimulus waveform. Depending on its direction, slow-activating subthreshold current cooperates or competes with fast-activating inward current during spike initiation. This explanation predicts that sensitivity to the rate of change of stimulus intensity differs qualitatively between integrators and differentiators. This was confirmed experimentally in spinal sensory neurons that naturally behave as specialized integrators or differentiators. Predicted sensitivity to different stimulus features was confirmed by covariance analysis. Integration and differentiation, which are themselves inverse operations, are thus shown to be implemented by the slow feedback mediated by oppositely directed subthreshold currents expressed in different neurons. PMID:25620913

  20. Variability of sea ice melt and meteoric water input in the surface Labrador Current off Newfoundland

    NASA Astrophysics Data System (ADS)

    Benetti, M.; Reverdin, G.; Pierre, C.; Khatiwala, S.; Tournadre, B.; Olafsdottir, S.; Naamar, A.

    2016-04-01

    The respective contributions of saline (Atlantic and Pacific water) and freshwater (sea ice melt, meteoric water) components in the surface Labrador Current are quantified using salinity, δ18O, and nutrient data collected between 2012 and 2015 east of Newfoundland to investigate the seasonal variability of salinity in relation with the different freshwater contributions. Nutrient data indicate that the surface saline water is composed on average over 2012-2015 of roughly 62% Atlantic Water and 38% Pacific Water. A large salinity seasonal cycle of ≈ 1.5 peak-to-peak amplitude is found over the middle continental shelf, which is explained by the freshwater input seasonal variability: 2/3 of the amplitude of the salinity seasonal cycle can be explained by meteoric water input and 1/3 by the sea ice melt. A smaller seasonal salinity cycle (≈1.3) is observed over the inner shelf compared to the middle shelf, because of smaller variability in the large meteoric water inputs. Furthermore, the data reveal that sea ice melt (SIM) input was particularly important during July 2014, following a larger extension of sea ice over the Labrador shelf during the 2013/2014 winter season, compared to both previous winter seasons. Some patches of large SIM contribution observed during July 2014 and April 2015 were located on the continental slope or further offshore. The comparison of 2012-2015 data with data collected in 1994-1995 shows that the surface water over the Newfoundland shelf and slope is strongly affected by sea ice processes in both periods and suggests a larger contribution of brines over the slope during 1994-1995.

  1. Design of an input filter for power factor correction (PFC) AC to DC converters employing an active ripple cancellation

    SciTech Connect

    Lee, D.Y.; Cho, B.H.

    1996-12-31

    An active input filter for power factor correction (PFC) circuit employing ripple current cancellation is proposed to reduce the filter`s size and cost.Switching ripple current can be filtered by an active circuit from the line current. A single stage passive filter with the active filter compensation circuit, a high filter can be synthesized to meet the electromagnetic interference (EMI) and power factor requirements. Analysis of the active filter and design procedure are detailed. Simulation result is presented to verify the high order filter characteristics of proposed scheme.

  2. Input Shaping enhanced Active Disturbance Rejection Control for a twin rotor multi-input multi-output system (TRMS).

    PubMed

    Yang, Xiaoyan; Cui, Jianwei; Lao, Dazhong; Li, Donghai; Chen, Junhui

    2016-05-01

    In this paper, a composite control based on Active Disturbance Rejection Control (ADRC) and Input Shaping is presented for TRMS with two degrees of freedom (DOF). The control tasks consist of accurately tracking desired trajectories and obtaining disturbance rejection in both horizontal and vertical planes. Due to un-measurable states as well as uncertainties stemming from modeling uncertainty and unknown disturbance torques, ADRC is employed, and feed-forward Input Shaping is used to improve the dynamical response. In the proposed approach, because the coupling effects are maintained in controller derivation, there is no requirement to decouple the TRMS into horizontal and vertical subsystems, which is usually performed in the literature. Finally, the proposed method is implemented on the TRMS platform, and the results are compared with those of PID and ADRC in a similar structure. The experimental results demonstrate the effectiveness of the proposed method. The operation of the controller allows for an excellent set-point tracking behavior and disturbance rejection with system nonlinearity and complex coupling conditions. PMID:26922492

  3. 77 FR 37696 - Agency Information Collection Activities: Importer ID Input Record

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-22

    ... SECURITY U.S. Customs and Border Protection Agency Information Collection Activities: Importer ID Input... other Federal agencies to comment on an information collection requirement concerning the Importer ID... concerning the following information collection: Title: Importer ID Input Record. OMB Number: 1651-0064....

  4. 78 FR 67383 - Agency Information Collection Activities; Importer ID Input Record

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-12

    ... SECURITY U.S. Customs and Border Protection Agency Information Collection Activities; Importer ID Input... other Federal agencies to comment on an information collection requirement concerning the Importer ID... concerning the following information collection: Title: Importer ID Input Record. OMB Number: 1651-0064....

  5. 77 FR 55486 - Agency Information Collection Activities: Importer ID Input Record

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-10

    ... Federal Register (76 FR 37696) on June 22, 2012, allowing for a 60-day comment period. This notice allows... SECURITY U.S. Customs and Border Protection Agency Information Collection Activities: Importer ID Input... accordance with the Paperwork Reduction Act: Importer ID Input Record (CBP Form 5106). This is a...

  6. Intelligence Current in Creative Activities

    ERIC Educational Resources Information Center

    Shi, Jiannong

    2004-01-01

    In this paper, the term 'intelligence current' is further explained and the problems found in relationships between (among) creativity, intelligence, attitude and environmental factors are discussed, according to the systematic model of creativity previously developed by the author. In this model, the performance of an individual's creativity is…

  7. Theoretical inputs and errors in the new hadronic currents in TAUOLA

    SciTech Connect

    Roig, P.; Nugent, I. M.; Przedzinski, T.; Shekhovtsova, O.; Was, Z.

    2012-10-23

    The new hadronic currents implemented in the TAUOLA library are obtained in the unified and consistent framework of Resonance Chiral Theory: a Lagrangian approach in which the resonances exchanged in the hadronic tau decays are active degrees of freedom included in a way that reproduces the low-energy results of Chiral Perturbation Theory. The short-distance QCD constraints on the imaginary part of the spin-one correlators yield relations among the couplings that render the theory predictive. In this communication, the obtaining of the two- and three-meson form factors is sketched. One of the criticisms to our framework is that the error may be as large as 1/3, since it is a realization of the large-N{sub C} limit of QCD in a meson theory. A number of arguments are given which disfavor that claim pointing to smaller errors, which would explain the phenomenological success of our description in these decays. Finally, other minor sources of error and current improvements of the code are discussed.

  8. Active control of sound fields in elastic cylinders by vibrational inputs

    NASA Technical Reports Server (NTRS)

    Jones, J. D.; Fuller, C. R.

    1987-01-01

    An experiment is performed to study the mechanisms of active control of sound fields in elastic cylinders via vibrational outputs. In the present method of control, a vibrational force input was used as the secondary control input to reduce the radiated acoustic field. For the frequencies considered, the active vibration technique provided good global reduction of interior sound even though only one actuator was used.

  9. The Roles of Structured Input Activities in Processing Instruction and the Kinds of Knowledge They Promote

    ERIC Educational Resources Information Center

    Marsden, Emma; Chen, Hsin-Ying

    2011-01-01

    This study aimed to isolate the effects of the two input activities in Processing Instruction: referential activities, which force learners to focus on a form and its meaning, and affective activities, which contain exemplars of the target form and require learners to process sentence meaning. One hundred and twenty 12-year-old Taiwanese learners…

  10. A current-type PWM rectifier with active damping function

    SciTech Connect

    Sato, Yukihiko; Kataoka, Teruo

    1996-05-01

    A new control method for current-type pulse-width modulation (PWM) rectifiers which can provide active damping function is presented. This damping function is effective only on the harmonic components of ac input current selectively. Thus steady-state waveform distortion and transient oscillation of the input current are reduced by the active damping effects. The active damping function can be realized by feedback control of an LC filter connected to the ac side of the rectifier, and it does not require any additional components in the main circuits, permitting a simple circuit configuration. The control system of the proposed PWM rectifier is analyzed by using a simple block diagram developed in the present paper. From the analytical results, the influence of the circuit parameters and control delay on the active damping effects and the stability of the operation are clarified to establish the design method. To confirm the effectiveness of the active damping function, some results of basic experiments are included. As an example of application of the active damping function, the proposed rectifier is applied to reduce the harmonic currents generated by conventional rectifiers operating in parallel with the proposed rectifier. Some experimental results in this application are also included.

  11. Ecosystem consequences of changing inputs of terrestrial dissolved organic matter to lakes: current knowledge and future challenges

    USGS Publications Warehouse

    Solomon, Christopher T.; Jones, Stuart E.; Weidel, Brian C.; Buffam, Ishi; Fork, Megan L; Karlsson, Jan; Larsen, Soren; Lennon, Jay T.; Read, Jordan S.; Sadro, Steven; Saros, Jasmine E.

    2015-01-01

    Lake ecosystems and the services that they provide to people are profoundly influenced by dissolved organic matter derived from terrestrial plant tissues. These terrestrial dissolved organic matter (tDOM) inputs to lakes have changed substantially in recent decades, and will likely continue to change. In this paper, we first briefly review the substantial literature describing tDOM effects on lakes and ongoing changes in tDOM inputs. We then identify and provide examples of four major challenges which limit predictions about the implications of tDOM change for lakes, as follows: First, it is currently difficult to forecast future tDOM inputs for particular lakes or lake regions. Second, tDOM influences ecosystems via complex, interacting, physical-chemical-biological effects and our holistic understanding of those effects is still rudimentary. Third, non-linearities and thresholds in relationships between tDOM inputs and ecosystem processes have not been well described. Fourth, much understanding of tDOM effects is built on comparative studies across space that may not capture likely responses through time. We conclude by identifying research approaches that may be important for overcoming those challenges in order to provide policy- and management-relevant predictions about the implications of changing tDOM inputs for lakes.

  12. Immune Challenge Activates Neural Inputs to the Ventrolateral Bed Nucleus of the Stria Terminalis

    PubMed Central

    Bienkowski, Michael S.; Rinaman, Linda

    2011-01-01

    Hypothalamo-pituitary-adrenal (HPA) axis activation in response to infection is an important mechanism by which the nervous system can suppress inflammation. HPA output is controlled by the hypothalamic paraventricular nucleus (PVN). Previously, we determined that noradrenergic inputs to the PVN contribute to, but do not entirely account for, the ability of bacterial endotoxin (i.e., lipopolysacharide, LPS) to activate the HPA axis. The present study investigated LPS-induced recruitment of neural inputs to the ventrolateral bed nucleus of the stria terminalis (vlBNST). GABAergic projections from the vlBNST inhibit PVN neurons at the apex of the HPA axis; thus, we hypothesize that LPS treatment activates inhibitory inputs to the vlBNST to thereby “disinhibit” the PVN and increase HPA output. To test this hypothesis, retrograde neural tracer was iontophoretically delivered into the vlBNST of adult male rats to retrogradely label central sources of axonal input. After one week, rats were injected i.p. with either LPS (200 µg/kg BW) or saline vehicle, and then perfused with fixative 2.5 hours later. Brains were processed for immunohistochemical localization of retrograde tracer and the immediate-early gene product, Fos (a marker of neural activation). Brain regions that provide inhibitory input to the vlBNST (e.g., caudal nucleus of the solitary tract, central amygdala, dorsolateral BNST) were preferentially activated by LPS, whereas sources of excitatory input (e.g., paraventricular thalamus, medial prefrontal cortex) were not activated or were activated less robustly. These results suggest that LPS treatment recruits central neural systems that actively suppress vlBNST neural activity, thereby removing a potent source of inhibitory control over the HPA axis. PMID:21402087

  13. Inferring electric fields and currents from ground magnetometer data - A test with theoretically derived inputs

    NASA Technical Reports Server (NTRS)

    Wolf, R. A.; Kamide, Y.

    1983-01-01

    Advanced techniques considered by Kamide et al. (1981) seem to have the potential for providing observation-based high time resolution pictures of the global ionospheric current and electric field patterns for interesting events. However, a reliance on the proposed magnetogram-inversion schemes for the deduction of global ionospheric current and electric field patterns requires proof that reliable results are obtained. 'Theoretical' tests of the accuracy of the magnetogram inversion schemes have, therefore, been considered. The present investigation is concerned with a test, involving the developed KRM algorithm and the Rice Convection Model (RCM). The test was successful in the sense that there was overall agreement between electric fields and currents calculated by the RCM and KRM schemes.

  14. The 'window' component of the low threshold Ca2+ current produces input signal amplification and bistability in cat and rat thalamocortical neurones.

    PubMed Central

    Williams, S R; Tóth, T I; Turner, J P; Hughes, S W; Crunelli, V

    1997-01-01

    1. The mechanism underlying a novel form of input signal amplification and bistability was investigated by intracellular recording in rat and cat thalamocortical (TC) neurones maintained in slices and by computer simulation with a biophysical model of these neurones. 2. In a narrow membrane potential range centred around -60 mV, TC neurones challenged with small (10-50 pA), short (50-200 ms) current steps produced a stereotyped, large amplitude hyperpolarization (> 20 mV) terminated by the burst firing of action potentials, leading to amplification of the duration and amplitude of the input signal, that is hereafter referred to as input signal amplification. 3. In the same voltage range centred around -60 mV, single evoked EPSPs and IPSPs also produced input signal amplification, indicating that this behaviour can be triggered by physiologically relevant stimuli. In addition, a novel, intrinsic, low frequency oscillation, characterized by a peculiar voltage dependence of its frequency and by the presence of plateau potentials on the falling phase of low threshold Ca2+ potentials, was recorded. 4. Blockade of pure Na+ and K+ currents by tetrodotoxin (1 microM) and Ba2+ (0.1-2.0 mM), respectively, did not affect input signal amplification, neither did the presence of excitatory or inhibitory amino acid receptor antagonists in the perfusion medium. 5. A decrease in [Ca2+]o (from 2 to 1 mM) and an increase in [Mg2+]o (from 2 to 10 mM), or the addition of Ni2+ (2-3 mM), abolished input signal amplification, while an increase in [Ca2+]o (from 2 to 8 mM) generated this behaviour in neurones where it was absent in control conditions. These results indicate the involvement of the low threshold Ca2+ current (IT) in input signal amplification, since the other Ca2+ currents of TC neurones are activated at potentials more positive than -40 mV. 6. Blockade of the slow inward mixed cationic current (Ih) by 4-(N-ethyl-N-phenylamino)-1,2-dimethyl-6-(methylamino

  15. Afferent input-associated reduction of muscle activity in microgravity environment.

    PubMed

    Kawano, F; Nomura, T; Ishihara, A; Nonaka, I; Ohira, Y

    2002-01-01

    Responses of electromyogram (EMG) of soleus, lateral portion of gastrocnemius (LG) and tibialis anterior (TA), and both afferent and efferent neurograms at the L(5) segmental level of the spinal cord, to altered gravity levels created by the parabolic flight of a jet airplane were investigated in adult rats. The EMG activity in antigravity soleus muscle gradually increased when the gravity was elevated from 1-G to 1.5-G (+23%) and 2-G (+67%) during the ascending phase of parabolic flight. The activity decreased approximately 72% from the 1-G level immediately when the rat was exposed to microgravity. The EMG level was maintained low during the 20-s microgravity, but it was restored immediately once the gravity level was increased to 1.5-G and then 1-G during the descending and recovery phase. The EMG level of LG also increased gradually when the gravity level was elevated and the level then decreased when the rat was exposed to microgravity (P>0.05). However, the activity level during the 20-s microgravity was identical to that obtained at 1-G. The EMG level of TA even increased insignificantly in response to the exposure to microgravity. The responses of afferent neurogram were similar to those of soleus EMG, even though the magnitude of the reduction of integrated neurogram level in response to microgravity exposure was small (approximately 26% vs. 1-G level) relative to that of soleus EMG. The level of efferent neurogram was also decreased, but only approximately 9% vs. 1-G level, during the 20-s microgravity. The data in the current study suggest that the afferent input is closely associated with the gravity-dependent muscular activity. PMID:12379265

  16. DENSITY CURRENTS IN ACTIVATED SLUDGE SECONDARY CLARIFIERS

    EPA Science Inventory

    Density currents form in activated sludge secondary clarifiers because the mixed liquor has a density greater than the treated wastewater in the clarifier. This causes the mixed liquor to plunge to the bottom of the clarifier establishing relatively high velocity currents within ...

  17. Active sway control of a gantry crane using hybrid input shaping and PID control schemes

    NASA Astrophysics Data System (ADS)

    Mohd Tumari, M. Z.; Shabudin, L.; Zawawi, M. A.; Shah, L. H. Ahmad

    2013-12-01

    This project presents investigations into the development of hybrid input-shaping and PID control schemes for active sway control of a gantry crane system. The application of positive input shaping involves a technique that can reduce the sway by creating a common signal that cancels its own vibration and used as a feed-forward control which is for controlling the sway angle of the pendulum, while the proportional integral derivative (PID) controller is used as a feedback control which is for controlling the crane position. The PID controller was tuned using Ziegler-Nichols method to get the best performance of the system. The hybrid input-shaping and PID control schemes guarantee a fast input tracking capability, precise payload positioning and very minimal sway motion. The modeling of gantry crane is used to simulate the system using MATLAB/SIMULINK software. The results of the response with the controllers are presented in time domains and frequency domains. The performances of control schemes are examined in terms of level of input tracking capability, sway angle reduction and time response specification.

  18. Optimal control of electric drive with simultaneous control inputs for motor current and flux

    NASA Astrophysics Data System (ADS)

    Pansyuk, V. I.

    1984-08-01

    A detailed mathematical analysis of the optimal control of a dc electric drive with a variable magnetic flux is presented. Expressions are found for the optimal controller. When this controller uses real time microprocessors control hardware, formulas are also derived for the various portions of the optimal process as well as the logic expressions for the switching of these parts of the process. The resulting optimal process differs from previous determinations in that the braking portion, when a resistance moment is present, contains a free run-down (passive braking) region, before and after which there can be regions of active braking, when the motor produces an electromagnetic moment. In one numerical example of step dc motor control, which is used to compare the optimal process found here with one developed earlier, power losses are found to be reduced by 5.44% with the new process. The entire solution of the problem using the procedure presented here reduces to finding the conditional extremum of some function of several variables whose number is no greater than the dimensionality of the system and does not lead to a boundary value problem.

  19. Neck motor unit activities induced by inputs from periodontal mechanoreceptors in rats.

    PubMed

    Zeredo, J L; Toda, K; Soma, K

    2002-01-01

    Clinical evidence suggests that head movements may be coupled with oro-facial functions, which are predominantly controlled by somatosensory inputs from the oro-facial area. However, the effects of specific modalities of sensory inputs on the neck muscles' motor activity are still unclear. In the present study, natural pressure stimulation was applied to the rat's upper first molars, while motor unit electromyographic activity was recorded from the dorsal neck splenius muscle. During the hold phase of pressure stimulation, clear tonic discharges were elicited in the splenius muscles on both sides. Mean threshold values were 622.3 mN (+/- 19.6 SEM, n = 39) and 496.8 mN (+/- 26.4 SEM, n = 43) for ipsi- and contralateral sides, respectively (p < 0.001, Mann-Whitney U test). Analysis of our data suggests that periodontal inputs may play an important role in controlling the motor activity of neck muscles, in addition to its well-known coordination of the masticatory function. PMID:11820365

  20. Noise-gated encoding of slow inputs by auditory brain stem neurons with a low-threshold K+ current.

    PubMed

    Gai, Yan; Doiron, Brent; Kotak, Vibhakar; Rinzel, John

    2009-12-01

    Phasic neurons, which do not fire repetitively to steady depolarization, are found at various stages of the auditory system. Phasic neurons are commonly described as band-pass filters because they do not respond to low-frequency inputs even when the amplitude is large. However, we show that phasic neurons can encode low-frequency inputs when noise is present. With a low-threshold potassium current (I(KLT)), a phasic neuron model responds to rising and falling phases of a subthreshold low-frequency signal with white noise. When the white noise was low-pass filtered, the phasic model also responded to the signal's trough but still not to the peak. In contrast, a tonic neuron model fired mostly to the signal's peak. To test the model predictions, whole cell slice recordings were obtained in the medial (MSO) and lateral (LSO) superior olivary neurons in gerbil from postnatal day 10 (P10) to 22. The phasic MSO neurons with strong I(KLT), mostly from gerbils aged P17 or older, showed firing patterns consistent with the preceding predictions. Moreover, injecting a virtual I(KLT) into weak-phasic MSO and tonic LSO neurons with putative weak or no I(KLT) (from gerbils younger than P17) shifted the neural response from the signal's peak to the rising phase. These findings advance our knowledge about how noise gates the signal pathway and how phasic neurons encode slow envelopes of sounds with high-frequency carriers. PMID:19812289

  1. Influences of laryngeal afferent inputs on intralaryngeal muscle activity during vocalization in the cat.

    PubMed

    Shiba, K; Yoshida, K; Nakajima, Y; Konno, A

    1997-01-01

    The present study was undertaken to elucidate the possible role of the laryngeal afferent inputs in the regulation of intralaryngeal muscle activity during vocalization. We studied the influences of airflow and/or pressure applied to the larynx on intralaryngeal muscle activity during vocalization in ketamine-anesthetized cats. Vocalization was induced by airflow applied to the upper airway, which was isolated from the lower airway, during pontine call site stimulation. When the upper airway was open to the atmosphere through the nostrils and mouth, the airflow increased not only the vocal fold adductor and tensor activities but also the duration of these activities. The adductor and tensor activities were increased suddenly at a critical subglottic pressure level equivalent to the subglottic pressure threshold for vocalization. These effects were significantly reduced by sectioning of the internal branch of the superior laryngeal nerve or by lidocaine application to the laryngeal mucosa. Sustained pressure applied to the isolated upper airway, when the mouth and nostrils were occluded, did not affect adductor or tensor activities. These results indicate that the afferent inputs evoked by vocal fold stretching or vibration play an important role in the motor control of intralaryngeal and respiratory muscles during vocalization. PMID:9089702

  2. A low power and low distortion rail-to-rail input/output amplifier using constant current technique

    NASA Astrophysics Data System (ADS)

    Yan, Liu; Yiqiang, Zhao; Shilin, Zhang; Hongliang, Zhao

    2011-04-01

    A rail-to-rail amplifier with constant transconductance, intended for audio processing, is presented. The constant transconductance is obtained by a constant current technique based on the input differential pairs operating in the weak inversion region. MOSFETs working in the weak inversion region have the advantages of low power and low distortion. The proposed rail-to-rail amplifier, fabricated in a standard 0.35 μm CMOS process, occupies a core die area of 75 × 183 μm2. Measured results show that the maximum power consumption is 85.37 μW with a supply voltage of 3.3 V and the total harmonic distortion level is 1.2% at 2 kHz.

  3. Active control of structurally-coupled sound fields in elastic cylinders by vibrational force inputs

    NASA Technical Reports Server (NTRS)

    Jones, J. D.; Fuller, C. R.

    1990-01-01

    Active control of structurally-coupled sound fields in elastic cylinders is analytically and experimentally studied. The primary (noise) field in the cylinder model is generated by the coupled dynamic response of the shell under loading by a single exterior acoustic source. Control of the interior sound field is achieved by applying vibrational force inputs directly to the shell wall. Action of the point controllers serve to increase the input impedance of select structural modes of the shell which are well-coupled to the interior acoustic cavity, thus substantially reducing sound transmission into the cavity. Spatially-averaged noise reductions in excess of 30 dB are demonstrated for acoustic resonant conditions within the cavity. Twin controller configurations are presented which demonstrate the ability to independently control orthogonal modes of the interior acoustic space. Benefits and drawbacks of this new methodology for noise control are discussed and clearly demonstrated.

  4. Active control of sound transmission/radiation from elastic plates by vibration inputs. II - Experiments

    NASA Technical Reports Server (NTRS)

    Metcalf, V. L.; Fuller, C. R.; Silcox, R. J.; Brown, D. E.

    1992-01-01

    Actively controlled harmonic force inputs were applied experimentally to reduce the sound transmitted through an elastic circular plate. The control implementation used a time domain least mean square adaptive algorithm with two error sensors. The control forces were applied directly to the plate by point force vibration inputs, while the error information and performance were measured in the radiated acoustic field by microphones. Test cases were also performed in which the error sensors were accelerometers mounted on the plate. When accelerometers were used as error sensors, the controller performance was degraded; leading to the conclusion that minimizing plate motion does not necessarily lead to an associated decrease in radiated sound levels. In contrast, the results show excellent attenuation of the transmitted sound field when microphone error sensors were used. This result was consistent over a range of frequencies. In addition, the experimental results are compared to previously derived analytical results and the effect of using a point or global minimization scheme is discussed.

  5. Short-term modulation of cerebellar Purkinje cell activity after spontaneous climbing fiber input.

    PubMed

    Sato, Y; Miura, A; Fushiki, H; Kawasaki, T

    1992-12-01

    1. There are two opposite points of view concerning the way climbing fiber input in a Purkinje cell modifies simple spike (SS) activity transiently: depression versus enhancement of SS activity. The different groups of investigators favored one effect predominating over the other. In the decerebrate unanesthetized cat, we recorded spontaneous activity of single Purkinje cells and investigated time course of SS activity after the complex spike (CS). 2. In the peri-CS time histogram, there was a SS pause lasting, on average, 10.8 ms after onset of the CS in all of the 316 cells recorded. The pause was followed by a rapid increase in SS activity to a maximum, which was on average 175.6% of a pre-CS control level, and a gradual return to around the control level in the majority of the cells recorded (pause-facilitation type, 71.2%). The increase in SS activity was significant (P < 0.01, t test) during 20-100 ms. The SS activity during the 20-100 ms was, on average, 163.7% of the control level. In some cells (pure-pause type, 25.3%), no significant changes were found (P > 0.01) in the post-pause SS firing. In contrast, only 3.5% of the cells (pause-reduction type) showed a significant (P < 0.01) firing decrease (average 54.0% of the control level) lasting 20-60 ms after the pause period. 3. Analysis of the pre-CS time histogram revealed no significant differences (P > 0.01) in the SS activity between pre-CS periods in all of the cells recorded, suggesting that the SS activity enhancement is not due to a coactivated mossy fiber input just preceding the activation of the climbing fiber input. 4. Analysis of the raster diagram revealed variability of individual SS responses after the CS. The probability of occurrence of the increase in SS number during a post-CS period of 0-100 ms with respect to that during a pre-CS period of -100-0 ms in individual raster traces was high (on average 78.2%), medium (57.3%), and low (36.3%) in the pause-facilitation, pure-pause, and pause

  6. Current Activities of the ASME Subgroup NUPACK

    SciTech Connect

    Gerald M. Foster; D. Keith Morton; Paul McConnell

    2007-10-01

    Current activities of the American Society of Mechanical Engineers (ASME), Section III Subgroup on Containment Systems for Spent Fuel High-Level Waste Transport Packagings (also known as Subgroup NUPACK) are reviewed with emphasis on the recent revision of Subsection WB. Also, brief insightson new proposals for the development of rules for internal support structures and for a strain-based acceptance criteria are provided.

  7. NMDA currents modulate the synaptic input-output functions of neurons in the dorsal nucleus of the lateral lemniscus in Mongolian gerbils.

    PubMed

    Porres, Christian P; Meyer, Elisabeth M M; Grothe, Benedikt; Felmy, Felix

    2011-03-23

    Neurons in the dorsal nucleus of the lateral lemniscus (DNLL) receive excitatory and inhibitory inputs from the superior olivary complex (SOC) and convey GABAergic inhibition to the contralateral DNLL and the inferior colliculi. Unlike the fast glycinergic inhibition in the SOC, this GABAergic inhibition outlasts auditory stimulation by tens of milliseconds. Two mechanisms have been postulated to explain this persistent inhibition. One, an "integration-based" mechanism, suggests that postsynaptic excitatory integration in DNLL neurons generates prolonged activity, and the other favors the synaptic time course of the DNLL output itself. The feasibility of the integration-based mechanism was tested in vitro in DNLL neurons of Mongolian gerbils by quantifying the cellular excitability and synaptic input-output functions (IO-Fs). All neurons were sustained firing and generated a near monotonic IO-F on current injections. From synaptic stimulations, we estimate that activation of approximately five fibers, each on average liberating ∼18 vesicles, is sufficient to trigger a single postsynaptic action potential. A strong single pulse of afferent fiber stimulation triggered multiple postsynaptic action potentials. The steepness of the synaptic IO-F was dependent on the synaptic NMDA component. The synaptic NMDA receptor current defines the slope of the synaptic IO-F by enhancing the temporal and spatial EPSP summation. Blocking this NMDA-dependent amplification during postsynaptic integration of train stimulations resulted into a ∼20% reduction of the decay time course of the GABAergic inhibition. Thus, our data show that the NMDA-dependent amplification of the postsynaptic activity contributes to the GABAergic persistent inhibition generated by DNLL neurons. PMID:21430152

  8. Sharp wave-associated synchronized inputs from the piriform cortex activate olfactory tubercle neurons during slow-wave sleep

    PubMed Central

    Narikiyo, Kimiya; Manabe, Hiroyuki

    2013-01-01

    During slow-wave sleep, anterior piriform cortex neurons show highly synchronized discharges that accompany olfactory cortex sharp waves (OC-SPWs). The OC-SPW-related synchronized activity of anterior piriform cortex neurons travel down to the olfactory bulb and is thought to be involved in the reorganization of bulbar neuronal circuitry. However, influences of the OC-SPW-related activity on other regions of the central olfactory system are still unknown. Olfactory tubercle is an area of OC and part of ventral striatum that plays a key role in reward-directed motivational behaviors. In this study, we show that in freely behaving rats, olfactory tubercle receives OC-SPW-associated synchronized inputs during slow-wave sleep. Local field potentials in the olfactory tubercle showed SPW-like activities that were in synchrony with OC-SPWs. Single-unit recordings showed that a subpopulation of olfactory tubercle neurons discharged in synchrony with OC-SPWs. Furthermore, correlation analysis of spike activity of anterior piriform cortex and olfactory tubercle neurons revealed that the discharges of anterior piriform cortex neurons tended to precede those of olfactory tubercle neurons. Current source density analysis in urethane-anesthetized rats indicated that the current sink of the OC-SPW-associated input was located in layer III of the olfactory tubercle. These results indicate that OC-SPW-associated synchronized discharges of piriform cortex neurons travel to the deep layer of the olfactory tubercle and drive discharges of olfactory tubercle neurons. The entrainment of olfactory tubercle neurons in the OC-SPWs suggests that OC-SPWs coordinate reorganization of neuronal circuitry across wide areas of the central olfactory system including olfactory tubercle during slow-wave sleep. PMID:24108798

  9. Dynamics of olfactory bulb input and output activity during odor stimulation in zebrafish.

    PubMed

    Friedrich, Rainer W; Laurent, Gilles

    2004-06-01

    The processing of odor-evoked activity in the olfactory bulb (OB) of zebrafish was studied by extracellular single unit recordings from the input and output neurons, i.e., olfactory receptor neurons (ORNs) and mitral cells (MCs), respectively. A panel of 16 natural amino acid odors was used as stimuli. Responses of MCs, but not ORNs, changed profoundly during the first few hundred milliseconds after response onset. In MCs, but not ORNs, the total evoked excitatory activity in the population was initially odor-dependent but subsequently converged to a common level. Hence, the overall population activity is regulated by network interactions in the OB. The tuning widths of both ORN and MC response profiles were similar and, on average, stable over time. However, when analyzed for individual neurons, MC response profiles could sharpen (excitatory response to fewer odors) or broaden (excitatory response to more odors), whereas ORN response profiles remained nearly unchanged. Several observations indicate that dynamic inhibition plays an important role in this remodeling. Finally, the reliability of odor identification based on MC population activity patterns improved over time, whereas odor identification based on ORN activity patterns was most reliable early in the odor response. These results demonstrate that several properties of MC, but not ORN, activity change during the initial phase of the odor response with important consequences for odor-encoding activity patterns. Furthermore, our data indicate that inhibitory interactions in the OB are important in dynamically shaping the activity of OB output neurons. PMID:14960561

  10. Saturn's Titan: Evidence for Current Cryovolcanic Activity

    NASA Astrophysics Data System (ADS)

    Nelson, Robert M.; Cassini VIMS Titan Surface Variability Group

    2009-09-01

    We report evidence suggesting current cryovolcanic activity on Titan. This is based on surface changes seen at selected locations by the Cassini Visual and Infrared Mapping Spectrometer (VIMS). Titan's surface is hard to observe because Titan's atmosphere is opaque at visual wavelengths due to methane absorption. However, VIMS is able to image the surface at selected infrared wavelengths where the methane is relatively transparent[1,2]. VIMS reported surface reflectance variability at Hotei Arcus (26S,78W) and that the variability might be due to deposition followed by coverage or dissipation of ammonia frost. Subsequently, Cassini RADAR images found that Hotei Arcus has lobate "flow” forms, consistent with the morphology of volcanic terrain [3]. Here we report the discovery of lobate "flow” patterns at Hotei Arcus in VIMS infrared images taken during Cassini close flybys during 2008-2009. These data further suggest that the brightness variability at Hotei Arcus is associated with ammonia, a compound expected in Titan's interior. This, combined with the previous evidence from VIMS and RADAR images, creates a strong case for Titan having a presently active surface, possibly due to cryovolcanism. It has not escaped our attention that gaseous ammonia, in association with methane and nitrogen in Titan's atmosphere, is similar to the terrestrial environment at the time that life first emerged. If Titan is currently active, then these results raise the following questions: What is the full extent of current geologic activity? What are the ongoing processes? Are Titan's chemical processes today supporting a prebiotic chemistry similar to that under which life evolved on Earth? This work done at JPL under contract with NASA. References: [1]R. M. Nelson et al., Icarus 199 (2009) 429-441. [2]R. M. Nelson et al., GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L04202, doi:10.1029/2008GL036206, 2009. [3]S. D. Wall GEOPHYSICAL RESEARCH LETTERS, VOL. 36, L04203, doi:10.1029/2008GL

  11. An ionic current model for neurons in the rat medial nucleus tractus solitarii receiving sensory afferent input.

    PubMed Central

    Schild, J H; Khushalani, S; Clark, J W; Andresen, M C; Kunze, D L; Yang, M

    1993-01-01

    1. Neurons from a horizontal slice of adult rat brainstem were examined using intracellular recording techniques. Investigations were restricted to a region within the nucleus tractus solitarii, medial to the solitary tract and centred on the obex (mNTS). Previous work has shown this restricted area of the NTS to contain the greatest concentration of aortic afferent baroreceptor terminal fields. Electrical stimulation of the tract elicited short-latency excitatory postsynaptic potentials in all neurons. 2. mNTS neurons were spontaneously active with firing frequencies ranging between 1 and 10 Hz, at resting potentials of -65 to -45 mV. These neurons did not exhibit spontaneous bursting activity. 3. Depolarizing current injection immediately evoked a finite, high-frequency spike discharge which rapidly declined to a lower steady-state level (i.e. spike frequency adaptation, SFA). Increasing depolarizations produced a marked increase in the peak instantaneous frequency but a much smaller increase in the steady-state firing level. 4. Conditioning with a hyperpolarizing prepulse resulted in a prolonged delay of up to 600 ms before the first action potential (i.e. delayed excitation, DE) with an attendant decrease in peak discharge rates. DE was modulated by both the magnitude and duration of the prestimulus hyperpolarization, as well as the magnitude of the depolarizing stimulus. Tetrodotoxin (TTX) eliminated spike discharge but had little effect on the ramp-like membrane depolarization characteristic of DE. 5. We have developed a mathematical model for mNTS neurons to facilitate our understanding of the interplay between the underlying ionic currents. It consists of a comprehensive membrane model of the Hodgkin-Huxley type coupled with a fluid compartment model describing cytoplasmic [Ca2+]i homeostasis. 6. The model suggests that (a) SFA is caused by an increase in [Ca2+]i which activates the outward K+ current, IK,Ca, and (b) DE results from the competitive

  12. Electric current-induced lymphatic activation.

    PubMed

    Kajiya, Kentaro; Matsumoto-Okazaki, Yuko; Sawane, Mika; Fukada, Kaedeko; Takasugi, Yuya; Akai, Tomonori; Saito, Naoki; Mori, Yuichiro

    2014-12-01

    The lymphatic system in skin plays important roles in drainage of wastes and in the afferent phase of immune response. We previously showed that activation of vascular endothelial growth factor receptor (VEGFR), specifically the VEGFC/VEGFR-3 pathway, attenuates oedema and inflammation by promoting lymphangiogenesis, suggesting a protective role of lymphatic vessels against skin inflammation. However, it remains unknown how physical stimuli promote lymphatic function. Here, we show that lymphatic endothelial cells (LECs) are activated by direct-current (DC) electrical stimulation, which induced extension of actin filaments of LECs, increased calcium influx into LECs, and increased phosphorylation of p38 mitogen-activated protein kinase (MAPK). An inhibitor of focal adhesion kinase, which plays a role in cellular adhesion and motility, diminished the DC-induced extension of F-actin and abrogated p38 phosphorylation. Time-lapse imaging revealed that pulsed-DC stimulation promoted proliferation and migration of LECs. Overall, these results indicate that electro-stimulation activates lymphatic function by activating p38 MAPK. PMID:25308203

  13. Optogenetic activation of presynaptic inputs in lateral amygdala forms associative fear memory

    PubMed Central

    Kwon, Jeong-Tae; Nakajima, Ryuichi; Kim, Hyung-Su; Jeong, Yire; Augustine, George J.

    2014-01-01

    In Pavlovian fear conditioning, the lateral amygdala (LA) has been highlighted as a key brain site for association between sensory cues and aversive stimuli. However, learning-related changes are also found in upstream sensory regions such as thalamus and cortex. To isolate the essential neural circuit components for fear memory association, we tested whether direct activation of presynaptic sensory inputs in LA, without the participation of upstream activity, is sufficient to form fear memory in mice. Photostimulation of axonal projections from the two main auditory brain regions, the medial geniculate nucleus of the thalamus and the secondary auditory cortex, was paired with aversive footshock. Twenty-four hours later the same photostimulation induced robust conditioned freezing and this fear memory formation was disrupted when glutamatergic synaptic transmission was locally blocked in the LA. Therefore, our results prove for the first time that synapses between sensory input areas and the LA, previously implicated as a crucial brain site for fear memory formation, actually are sufficient to serve as a conditioned stimulus. Our results strongly support the idea that the LA may be sufficient to encode and store associations between neutral cue and aversive stimuli during natural fear conditioning as a critical part of a broad fear memory engram. PMID:25322798

  14. Opening remarks: Current and future activities

    NASA Astrophysics Data System (ADS)

    Davarian, Faramaz

    1993-08-01

    It is our custom to present the Propagation Program's recent accomplishments and future plans at the onset of a NAPEX meeting. A summary is presented. The data analysis phase of the U.S. Olympus Campaign is nearing its end. The final report will be published by Virginia Tech by midsummer 1993. The report will comprise measurement analysis for 12 months. It will include monthly and annual attenuation statistics and statistics on scintillation effects. A number of prediction models will be presented. The ACTS propagation experiment preparations are moving forward as expected. The mobile/personal channel characterization efforts continued during the last year. Data collected by the University of Texas in 1992 are being analyzed and will become available by September 1993. We have recently started a study to characterize LEO mobile/personal channels. Topics such as indoor reception, tree shadowing, blockage, and delay spread will be investigated. These results will become available in one to two years from now. We have also collected Ka-band mobile data using Olympus 20 GHz beacon transmissions. The University of Texas has already collected five years of low-elevation angle, 11GHz propagation data. The work on database for propagation models has progressed very well. The first release is ready, and the participants of this meeting will receive a copy of the software. We had an active year where CCIR is concerned. input document on land mobile satellite system (LMSS) propagation models was submitted to the U.S. national committee and was approved and sent to Geneva.

  15. Pederson Current Dissipation In Emerging Active Regions

    NASA Astrophysics Data System (ADS)

    Leake, James E.; Linton, M. G.

    2011-05-01

    Pederson current dissipation in emerging active regions. Certain regions of the solar atmosphere, such as the photosphere and chromosphere, as well as prominences, contain a significant amount of neutral atoms, and a complete description of the plasma requires including the effects of partial ionization. In the chromosphere the dissipation of Pederson currents is important for the evolution of emerging magnetic fields. Due to the relatively high number density in the chromosphere, the ion-neutral collision time-scale is much smaller than timescales associated with flux emergence. Hence we use a single-fluid approach to model the partially ionized plasma. Looking at both the emergence of large-scale sub-surface structures, and the emergence and reconnection of undulatory fields, we investigate the effect of Pederson current dissipation on the state of the emerging field, on magnetic reconnection and on dissipative heating of the atmosphere. Specifically we examine the effect of motions across fieldlines in the partially ionized regions, and how this can increase the free energy supplied to the corona by flux emergence. We also look at reconnection associated with flux emergence in the partially ionized atmosphere, and how this can account for observed small-scale brightenings (Ellerman Bombs).

  16. Alternating Current Influences Anaerobic Electroactive Biofilm Activity.

    PubMed

    Wang, Xin; Zhou, Lean; Lu, Lu; Lobo, Fernanda Leite; Li, Nan; Wang, Heming; Park, Jaedo; Ren, Zhiyong Jason

    2016-09-01

    Alternating current (AC) is known to inactivate microbial growth in suspension, but how AC influences anaerobic biofilm activities has not been systematically investigated. Using a Geobacter dominated anaerobic biofilm growing on the electrodes of microbial electrochemical reactors, we found that high frequency AC ranging from 1 MHz to 1 kHz (amplitude of 5 V, 30 min) showed only temporary inhibition to the biofilm activity. However, lower frequency (100 Hz, 1.2 or 5 V) treatment led to 47 ± 19% permanent decrease in limiting current on the same biofilm, which is attributed to the action of electrohydrodynamic force that caused biofilm damage and loss of intercellular electron transfer network. Confocal microscopy images show such inactivation mainly occurred at the interface between the biofilm and the electrode. Reducing the frequency further to 1 Hz led to water electrolysis, which generated gas bubbles that flushed all attached cells out of the electrode. These findings provide new references on understanding and regulating biofilm growth, which has broader implications in biofouling control, anaerobic waste treatment, energy and product recovery, and general understanding of microbial ecology and physiology. PMID:27485403

  17. Biased low differential input impedance current receiver/converter device and method for low noise readout from voltage-controlled detectors

    DOEpatents

    Degtiarenko, Pavel V.; Popov, Vladimir E.

    2011-03-22

    A first stage electronic system for receiving charge or current from voltage-controlled sensors or detectors that includes a low input impedance current receiver/converter device (for example, a transimpedance amplifier), which is directly coupled to the sensor output, a source of bias voltage, and the device's power supply (or supplies), which use the biased voltage point as a baseline.

  18. Orexin Receptor Activation Generates Gamma Band Input to Cholinergic and Serotonergic Arousal System Neurons and Drives an Intrinsic Ca2+-Dependent Resonance in LDT and PPT Cholinergic Neurons

    PubMed Central

    Ishibashi, Masaru; Gumenchuk, Iryna; Kang, Bryan; Steger, Catherine; Lynn, Elizabeth; Molina, Nancy E.; Eisenberg, Leonard M.; Leonard, Christopher S.

    2015-01-01

    A hallmark of the waking state is a shift in EEG power to higher frequencies with epochs of synchronized intracortical gamma activity (30–60 Hz) – a process associated with high-level cognitive functions. The ascending arousal system, including cholinergic laterodorsal (LDT) and pedunculopontine (PPT) tegmental neurons and serotonergic dorsal raphe (DR) neurons, promotes this state. Recently, this system has been proposed as a gamma wave generator, in part, because some neurons produce high-threshold, Ca2+-dependent oscillations at gamma frequencies. However, it is not known whether arousal-related inputs to these neurons generate such oscillations, or whether such oscillations are ever transmitted to neuronal targets. Since key arousal input arises from hypothalamic orexin (hypocretin) neurons, we investigated whether the unusually noisy, depolarizing orexin current could provide significant gamma input to cholinergic and serotonergic neurons, and whether such input could drive Ca2+-dependent oscillations. Whole-cell recordings in brain slices were obtained from mice expressing Cre-induced fluorescence in cholinergic LDT and PPT, and serotonergic DR neurons. After first quantifying reporter expression accuracy in cholinergic and serotonergic neurons, we found that the orexin current produced significant high frequency, including gamma, input to both cholinergic and serotonergic neurons. Then, by using a dynamic clamp, we found that adding a noisy orexin conductance to cholinergic neurons induced a Ca2+-dependent resonance that peaked in the theta and alpha frequency range (4–14 Hz) and extended up to 100 Hz. We propose that this orexin current noise and the Ca2+ dependent resonance work synergistically to boost the encoding of high-frequency synaptic inputs into action potentials and to help ensure cholinergic neurons fire during EEG activation. This activity could reinforce thalamocortical states supporting arousal, REM sleep, and intracortical gamma. PMID

  19. GIS interoperability: current activities and military implications

    NASA Astrophysics Data System (ADS)

    Lam, Sylvia

    1997-07-01

    Geographic information systems (GIS) are gaining importance in military operations because of their capability to spatially and visually integrate various kinds of information. In an era of limited resources, geospatial data must be shared efficiently whenever possible. The military-initiated Global Geospatial Information and Services (GGI&S) Project aims at developing the infrastructure for GIS interoperability for the military. Current activities in standardization and new technology have strong implications on the design and development of GGI&S. To facilitate data interoperability at both the national and international levels, standards and specifications in geospatial data sharing are being studied, developed and promoted. Of particular interest to the military community are the activities related to the NATO DIGEST, ISO TC/211 Geomatics standardization and the industry-led Open Geodata Interoperability Specifications (OGIS). Together with new information technology, standardization provides the infrastructure for interoperable GIS for both civilian and military environments. The first part of this paper describes the major activities in standardization. The second part presents the technologies developed at DREV in support of the GGI&S. These include the Open Geospatial Datastore Interface (OGDI) and the geospatial data warehouse. DREV has been working closely with Defence Geomatics and private industry in the research and development of new technology for the GGI&S project.

  20. Variation in active and passive resource inputs to experimental pools: mechanisms and possible consequences for food webs

    USGS Publications Warehouse

    Kraus, Johanna M.; Pletcher, Leanna T.; Vonesh, James R.

    2010-01-01

    1. Cross-ecosystem movements of resources, including detritus, nutrients and living prey, can strongly influence food web dynamics in recipient habitats. Variation in resource inputs is thought to be driven by factors external to the recipient habitat (e.g. donor habitat productivity and boundary conditions). However, inputs of or by ‘active’ living resources may be strongly influenced by recipient habitat quality when organisms exhibit behavioural habitat selection when crossing ecosystem boundaries. 2. To examine whether behavioural responses to recipient habitat quality alter the relative inputs of ‘active’ living and ‘passive’ detrital resources to recipient food webs, we manipulated the presence of caged predatory fish and measured biomass, energy and organic content of inputs to outdoor experimental pools of adult aquatic insects, frog eggs, terrestrial plant matter and terrestrial arthropods. 3. Caged fish reduced the biomass, energy and organic matter donated to pools by tree frog eggs by ∼70%, but did not alter insect colonisation or passive allochthonous inputs of terrestrial arthropods and plant material. Terrestrial plant matter and adult aquatic insects provided the most energy and organic matter inputs to the pools (40–50%), while terrestrial arthropods provided the least (7%). Inputs of frog egg were relatively small but varied considerably among pools and over time (3%, range = 0–20%). Absolute and proportional amounts varied by input type. 4. Aquatic predators can strongly affect the magnitude of active, but not passive, inputs and that the effect of recipient habitat quality on active inputs is variable. Furthermore, some active inputs (i.e. aquatic insect colonists) can provide similar amounts of energy and organic matter as passive inputs of terrestrial plant matter, which are well known to be important. Because inputs differ in quality and the trophic level they subsidise, proportional changes in input type could have

  1. Nursing Home Staffing Requirements and Input Substitution: Effects on Housekeeping, Food Service, and Activities Staff

    PubMed Central

    Bowblis, John R; Hyer, Kathryn

    2013-01-01

    Objective To study the effect of minimum nurse staffing requirements on the subsequent employment of nursing home support staff. Data Sources Nursing home data from the Online Survey Certification and Reporting (OSCAR) System merged with state nurse staffing requirements. Study Design Facility-level housekeeping, food service, and activities staff levels are regressed on nurse staffing requirements and other controls using fixed effect panel regression. Data Extraction Method OSCAR surveys from 1999 to 2004. Principal Findings Increases in state direct care and licensed nurse staffing requirements are associated with decreases in the staffing levels of all types of support staff. Conclusions Increased nursing home nurse staffing requirements lead to input substitution in the form of reduced support staffing levels. PMID:23445455

  2. Hindlimb movement modulates the activity of rostral fastigial nucleus neurons that process vestibular input

    PubMed Central

    McCall, Andrew A; Miller, Daniel J; Catanzaro, Michael F; Cotter, Lucy A; Yates, Bill J

    2015-01-01

    Integration of vestibular and proprioceptive afferent information within the central nervous system is a critical component of postural regulation. We recently demonstrated that labyrinthine and hindlimb signals converge onto vestibular nucleus neurons, such that hindlimb movement modulates the activity of these cells. However, it is unclear whether similar convergence of hindlimb and vestibular signals also occurs upstream from the vestibular nuclei, particularly in the rostral fastigial nucleus (rFN). We tested the hypothesis that rFN neurons have similar responses to hindlimb movement as vestibular nucleus neurons. Recordings were obtained from 53 rFN neurons that responded to hindlimb movement in decerebrate cats. In contrast to vestibular nucleus neurons, which commonly encoded the direction of hindlimb movement (81% of neurons), few rFN neurons (21%) that responded to leg movement encoded such information. Instead, most rFN neurons responded to both limb flexion and extension. Half of the rFN neurons whose activity was modulated by hindlimb movement received convergent vestibular inputs. These results show that rFN neurons receive somatosensory inputs from the hindlimb, and that a subset of rFN neurons integrates vestibular and hindlimb signals. Such rFN neurons likely perform computations that participate in maintenance of balance during upright stance and movement. Although vestibular nucleus neurons are interconnected with the rFN, the dissimilarity of responses of neurons sensitive to hindlimb movement in the two regions suggest that they play different roles in coordinating postural responses during locomotion and other movements which entail changes in limb position. PMID:25976518

  3. Hindlimb movement modulates the activity of rostral fastigial nucleus neurons that process vestibular input.

    PubMed

    McCall, Andrew A; Miller, Daniel J; Catanzaro, Michael F; Cotter, Lucy A; Yates, Bill J

    2015-08-01

    Integration of vestibular and proprioceptive afferent information within the central nervous system is a critical component of postural regulation. We recently demonstrated that labyrinthine and hindlimb signals converge onto vestibular nucleus neurons, such that hindlimb movement modulates the activity of these cells. However, it is unclear whether similar convergence of hindlimb and vestibular signals also occurs upstream from the vestibular nuclei, particularly in the rostral fastigial nucleus (rFN). We tested the hypothesis that rFN neurons have similar responses to hindlimb movement as vestibular nucleus neurons. Recordings were obtained from 53 rFN neurons that responded to hindlimb movement in decerebrate cats. In contrast to vestibular nucleus neurons, which commonly encoded the direction of hindlimb movement (81 % of neurons), few rFN neurons (21 %) that responded to leg movement encoded such information. Instead, most rFN neurons responded to both limb flexion and extension. Half of the rFN neurons whose activity was modulated by hindlimb movement received convergent vestibular inputs. These results show that rFN neurons receive somatosensory inputs from the hindlimb and that a subset of rFN neurons integrates vestibular and hindlimb signals. Such rFN neurons likely perform computations that participate in maintenance of balance during upright stance and movement. Although vestibular nucleus neurons are interconnected with the rFN, the dissimilarity of responses of neurons sensitive to hindlimb movement in the two regions suggests that they play different roles in coordinating postural responses during locomotion and other movements which entail changes in limb position. PMID:25976518

  4. Sex Differences in Neurophysiological Activation Patterns During Phonological Input Processing: An Influencing Factor for Normative Data.

    PubMed

    Aerts, Annelies; van Mierlo, Pieter; Hartsuiker, Robert J; Santens, Patrick; De Letter, Miet

    2015-11-01

    In the context of neurophysiological normative data, it has been established that aging has a significant impact on neurophysiological correlates of auditory phonological input processes, such as phoneme discrimination (PD) and word recognition (WR). Besides age, sex is another demographic factor that influences several language processes. We aimed to disentangle whether sex has a similar effect on PD and WR. Event-related potentials (ERPs) were recorded in 20 men and 24 women. During PD, three phonemic contrasts (place and manner of articulation and voicing) were compared using the attentive P300 and pre-attentive Mismatch Negativity. To investigate WR, real words were contrasted with pseudowords in a pre-attentive oddball task. Women demonstrated a larger sensitivity to spectrotemporal differences, as evidenced by larger P300 responses to the place of articulation (PoA) contrast and larger P300 and MMN responses than men in PoA-based PD. Men did not display such sensitivity. Attention played an important role, considering that women needed more attentional resources to differentiate between PoA and the other phonemic contrasts. During WR, pseudowords evoked larger amplitudes already 100 ms post-stimulus independent of sex. However, women had decreased P200 latencies, but longer N400 latencies in response to pseudowords, whereas men showed increased N400 latencies compared to women in response to real words. The current results demonstrate significant sex-related influences on phonological input processes. Therefore, existing neurophysiological normative data for age should be complemented for the factor sex. PMID:26014826

  5. 1 kW, 9 kV dc-dc converter module with time-sharing control of output voltage and input current

    SciTech Connect

    Borgatti, R.; Stefani, R.; Bressan, O.; Bicciato, F.; Tenti, P.; Rossetto, L.

    1993-10-01

    The paper describes a dc-dc power module based on a single-stage current-fed converter structure. Control is made according to a time-sharing strategy allowing simultaneous regulation of output voltage and input current. This solution is suitable for high-performance space and avionic applications, giving high efficiency, compactness, and accuracy, speed and robustness of control. Theoretical analysis, design criteria, and experimental results are reported. Application to radar supplies is discussed.

  6. Nonlinear compensation to enhance the input dynamic range in analog optical fiber links for the high current short circuit test

    NASA Astrophysics Data System (ADS)

    Rodriguez, Joaquin; Garduno, Raul; Velazquez, Jose; Montero, Julio

    2010-06-01

    Due to their galvanic insulation and EMI immunity properties, optical fiber links have been used in the transmitter-receiver system of an analog voltage measuring system at a high-power mid-voltage testing laboratory with a highly aggressive EMI environment. This paper introduces the application of a nonlinear compensation to limit the voltage range at the input of a voltage-controlled oscillator, which is used to produce the pulsed frequency modulation needed to transmit the analog signals over the optical fiber links. The proposed dynamic range compensation system is based on nonlinear circuits to accommodate the input range of the voltage-controlled oscillator. This approach increases the transient signal handling capabilities of the measuring system. This work demonstrates that the nonlinear compensated optical fiber approach yields a unique, electrically isolated, lightning-proof analog data transmission system, for remote measuring systems in the highly aggressive EMI environment of high-power test laboratories.

  7. HEAT INPUT AND POST WELD HEAT TREATMENT EFFECTS ON REDUCED-ACTIVATION FERRITIC/MARTENSITIC STEEL FRICTION STIR WELDS

    SciTech Connect

    Tang, Wei; Chen, Gaoqiang; Chen, Jian; Yu, Xinghua; Frederick, David Alan; Feng, Zhili

    2015-01-01

    Reduced-activation ferritic/martensitic (RAFM) steels are an important class of structural materials for fusion reactor internals developed in recent years because of their improved irradiation resistance. However, they can suffer from welding induced property degradations. In this paper, a solid phase joining technology friction stir welding (FSW) was adopted to join a RAFM steel Eurofer 97 and different FSW parameters/heat input were chosen to produce welds. FSW response parameters, joint microstructures and microhardness were investigated to reveal relationships among welding heat input, weld structure characterization and mechanical properties. In general, FSW heat input results in high hardness inside the stir zone mostly due to a martensitic transformation. It is possible to produce friction stir welds similar to but not with exactly the same base metal hardness when using low power input because of other hardening mechanisms. Further, post weld heat treatment (PWHT) is a very effective way to reduce FSW stir zone hardness values.

  8. Discerning Neurogenic vs. Non-Neurogenic Postnatal Lateral Ventricular Astrocytes via Activity-Dependent Input

    PubMed Central

    Adlaf, Elena W.; Mitchell-Dick, Aaron; Kuo, Chay T.

    2016-01-01

    Throughout development, neural stem cells (NSCs) give rise to differentiated neurons, astrocytes, and oligodendrocytes which together modulate perception, memory, and behavior in the adult nervous system. To understand how NSCs contribute to postnatal/adult brain remodeling and repair after injury, the lateral ventricular (LV) neurogenic niche in the rodent postnatal brain serves as an excellent model system. It is a specialized area containing self-renewing GFAP+ astrocytes functioning as NSCs generating new neurons throughout life. In addition to this now well-studied regenerative process, the LV niche also generates differentiated astrocytes, playing an important role for glial scar formation after cortical injury. While LV NSCs can be clearly distinguished from their neuroblast and oligodendrocyte progeny via molecular markers, the astrocytic identity of NSCs has complicated their distinction from terminally-differentiated astrocytes in the niche. Our current models of postnatal/adult LV neurogenesis do not take into account local astrogenesis, or the possibility that cellular markers may be similar between non-dividing GFAP+ NSCs and their differentiated astrocyte daughters. Postnatal LV neurogenesis is regulated by NSC-intrinsic mechanisms interacting with extracellular/niche-driven cues. It is generally believed that these local effects are responsible for sustaining neurogenesis, though behavioral paradigms and disease states have suggested possibilities for neural circuit-level modulation. With recent experimental findings that neuronal stimulation can directly evoke responses in LV NSCs, it is possible that this exciting property will add a new dimension to identifying postnatal/adult NSCs. Here, we put forth a notion that neural circuit-level input can be a distinct characteristic defining postnatal/adult NSCs from non-neurogenic astroglia. PMID:27047330

  9. Visual input controls the functional activity of goldfish Mauthner neuron through the reciprocal synaptic mechanism.

    PubMed

    Moshkov, Dmitry A; Shtanchaev, Rashid S; Mikheeva, Irina B; Bezgina, Elena N; Kokanova, Nadezhda A; Mikhailova, Gulnara Z; Tiras, Nadezhda R; Pavlik, Lyubov' L

    2013-03-01

    Goldfish are known to exhibit motor asymmetry due to functional asymmetry of their Mauthner neurons that induce the turns to the right or left during free swimming. It has been previously found that if the less active neuron is subjected to prolonged aimed visual stimulation via its ventral dendrite, the motor asymmetry of goldfish is inverted, testifying that this neuron becomes functionally dominant, while the size of the ventral dendrite under these conditions is reduced 2-3 times compared to its counterpart in mirror neuron. Earlier it has been also revealed that training optokinetic stimulation induces adaptation, a substantial resistance of both fish motor asymmetry and morphofunctional state of Mauthner neurons against prolonged optokinetic stimulation. The aim of this work was to study the cellular mechanisms of the effect of an unusual visual afferent input on goldfish motor asymmetry and Mauthner neuron function in norm and under adaptation. It was shown that serotonin applied onto Mauthner neurons greatly reduces their activity whereas its antagonist ondansetron increases it. Against the background of visual stimulation, serotonin strengthens functional asymmetry between neurons whereas ondansetron smoothes it. Taken together these data suggest the involvement of serotonergic excitatory synaptic transmission in the regulation of Mauthner neurons by vision. Ultrastructural study of the ventral dendrites after prolonged optokinetic stimulation has revealed depletions of numeral axo-axonal synapses with specific morphology, identified by means of immunogold label as serotonergic ones. These latter in turn are situated mainly on shaft boutons, which according to specific ultrastructural features are assigned to axo-dendritic inhibitory synapses. Thus, the excitatory serotonergic synapses seem to affect Mauthner neuron indirectly through inhibitory synapses. Further, it was morphometrically established that adaptation is accompanied by the significant

  10. Active Debris Removal: Current Status of Activities in CNES

    NASA Astrophysics Data System (ADS)

    Bonnal, Christophe; Ruault, Jean-Marc; Desjean, Marie-Christine

    2013-08-01

    Most of the ongoing studies led at worldwide level, mainly through IADC Actions, conclude that in order to keep a stable Low Earth Orbit environment in the coming decades, it may be necessary to retrieve some 5 to 10 large objects annually. These operations, known as Active Debris Removal (ADR), raise a huge amount of difficulties in numerous domains: political, legal, insurance, defense, financing and, last but not least, technical questions. The current paper aims at reviewing the current status of the ADR activities led by CNES both at National and Multi-lateral level. The first question which is raised is that of the high level requirements to be applied. What are the requirements coming from the operators; do we want to stabilize the environment, decrease it or could we accept some increase over the years; when do we have to act; can we baseline random reentry of such large objects or do we have to stick to controlled destructive reentries?… There may not yet be clear answers to these points, so efforts at international level are required. The second part of the paper deals with the potential solutions at system level. Numerous possibilities can be identified, depending on the size of the launcher and of the strategy selected to de-orbit the debris. Large space tugs visiting some 10 debris or small dedicated chasers launched as piggyback are among the solutions which have been traded. The currently preferred solution is described in details. The third part of the paper is devoted to the chaser-debris operations themselves, following five key functions; - the long range rendezvous, - the short range rendezvous up to contact, - the mechanical interfacing of the debris, - its control by the chaser, when required, - the de-orbiting maneuver itself. For each of these functions, the current status of available technologies is described, enabling the identification of the most critical ones requiring additional R&T effort and subsequent demonstrations. Among them

  11. Ex vivo dissection of optogenetically activated mPFC and hippocampal inputs to neurons in the basolateral amygdala: implications for fear and emotional memory

    PubMed Central

    Hübner, Cora; Bosch, Daniel; Gall, Andrea; Lüthi, Andreas; Ehrlich, Ingrid

    2014-01-01

    Many lines of evidence suggest that a reciprocally interconnected network comprising the amygdala, ventral hippocampus (vHC), and medial prefrontal cortex (mPFC) participates in different aspects of the acquisition and extinction of conditioned fear responses and fear behavior. This could at least in part be mediated by direct connections from mPFC or vHC to amygdala to control amygdala activity and output. However, currently the interactions between mPFC and vHC afferents and their specific targets in the amygdala are still poorly understood. Here, we use an ex-vivo optogenetic approach to dissect synaptic properties of inputs from mPFC and vHC to defined neuronal populations in the basal amygdala (BA), the area that we identify as a major target of these projections. We find that BA principal neurons (PNs) and local BA interneurons (INs) receive monosynaptic excitatory inputs from mPFC and vHC. In addition, both these inputs also recruit GABAergic feedforward inhibition in a substantial fraction of PNs, in some neurons this also comprises a slow GABAB-component. Amongst the innervated PNs we identify neurons that project back to subregions of the mPFC, indicating a loop between neurons in mPFC and BA, and a pathway from vHC to mPFC via BA. Interestingly, mPFC inputs also recruit feedforward inhibition in a fraction of INs, suggesting that these inputs can activate dis-inhibitory circuits in the BA. A general feature of both mPFC and vHC inputs to local INs is that excitatory inputs display faster rise and decay kinetics than in PNs, which would enable temporally precise signaling. However, mPFC and vHC inputs to both PNs and INs differ in their presynaptic release properties, in that vHC inputs are more depressing. In summary, our data describe novel wiring, and features of synaptic connections from mPFC and vHC to amygdala that could help to interpret functions of these interconnected brain areas at the network level. PMID:24634648

  12. Current experimental activities for solid breeder development

    SciTech Connect

    Johnson, C.E.; Hollenberg, G.W.; Roux, N.; Watanabe, H.

    1988-01-01

    The current data base for ceramic breeder materials does not exhibit any negative features as regards to thermophysical, mechanical, and irradiation behavior. All candidate materials show excellent stability for irradiation testing to 3% burnup. In-situ tritium recovery tests show very low tritium inventories for all candidates. Theoretical models are being developed to accurately predict real time release rates. Fabrication of kilogram quantities of materials has been achieved and technology is available for further scale-up.

  13. Effects of Phonological Input as a Pre-Listening Activity on Vocabulary Learning and L2 Listening Comprehension Test Performance

    ERIC Educational Resources Information Center

    Mihara, Kei

    2015-01-01

    The purpose of the present study is twofold. The first goal is to examine the effects of phonological input on students' vocabulary learning. The second is to discuss how different pre­-listening activities affect students' second language listening comprehension. The participants were first-­year students at a Japanese university. There were two…

  14. Improved Active Clamp Converter By Resonance Blanking Used For Wide Input Voltage Range

    NASA Astrophysics Data System (ADS)

    Strixner, E.; Godzik, S.

    2011-10-01

    The GPS line receiver as a standard product line of Astrium GmbH Ottobrunn shall operate according to customer requirements on different power busses with no or only minor modifications. Consequently there is an up coming demand to develop a power converter with a wide input voltage range. The hardware shall work with minor adaptation on all standard bus voltages of 28V, 50V and 100V. Themainfocuswas to cover the unregulated 28V bus and the regulated 50V bus without any modifications on the converter module and providing performance data being similar to low input voltage range converters.

  15. Direct Evidence for Active Suppression of Salient-but-Irrelevant Sensory Inputs

    PubMed Central

    Gaspelin, Nicholas; Leonard, Carly J.; Luck, Steven J.

    2016-01-01

    Researchers have long debated whether attentional capture is purely stimulus-driven or purely goal-driven. In the current study, we test a hybrid account called the signal suppression hypothesis, which posits that stimuli automatically produce a bottom-up salience signal, but that this signal can be suppressed via top-down control processes. To test this account, we used a new capture-probe paradigm in which participants searched for a target shape while ignoring irrelevant color singletons. On occasional probe trials, letters were briefly presented inside the search shapes, and participants attempted to report these letters. Under conditions that promoted capture by singletons, accuracy was greater for the letter inside this singleton than for letters inside nonsingleton objects. However, when the conditions were changed to avoid capture by the singleton, accuracy for the letter inside the irrelevant singleton was reduced below the level observed for nonsingleton objects, indicating active suppression of the singleton. PMID:26420441

  16. Rhythmic activity of neurons in the rostral ventrolateral medulla of conscious cats: effect of removal of vestibular inputs.

    PubMed

    Barman, Susan M; Sugiyama, Yoichiro; Suzuki, Takeshi; Cotter, Lucy A; DeStefino, Vincent J; Reighard, Derek A; Cass, Stephen P; Yates, Bill J

    2011-10-01

    Although it is well established that bulbospinal neurons located in the rostral ventrolateral medulla (RVLM) play a pivotal role in regulating sympathetic nerve activity and blood pressure, virtually all neurophysiological studies of this region have been conducted in anesthetized or decerebrate animals. In the present study, we used time- and frequency-domain analyses to characterize the naturally occurring discharges of RVLM neurons in conscious cats. Specifically, we compared their activity to fluctuations in carotid artery blood flow to identify neurons with cardiac-related (CR) activity; we then considered whether neurons with CR activity also had a higher-frequency rhythmic firing pattern. In addition, we ascertained whether the surgical removal of vestibular inputs altered the rhythmic discharge properties of RVLM neurons. Less than 10% of RVLM neurons expressed CR activity, although the likelihood of observing a neuron with CR activity in the RVLM varied between recording sessions, even when tracking occurred in a very limited area and was higher after vestibular inputs were surgically removed. Either a 10-Hz or a 20- to 30-Hz rhythmic discharge pattern coexisted with the CR discharges in some of the RVLM neurons. Additionally, the firing rate of RVLM neurons, including those with CR activity, decreased after vestibular lesions. These findings raise the prospect that RVLM neurons may or may not express rhythmic firing patterns at a particular time due to a variety of influences, including descending projections from higher brain centers and sensory inputs, such as those from the vestibular system. PMID:21734018

  17. Current natural products with antihypertensive activity.

    PubMed

    Bai, Ren-Ren; Wu, Xiao-Ming; Xu, Jin-Yi

    2015-10-01

    Natural products have been an important source of new drugs, which also played a dominant role in the discovery and research of new drugs for the treatment of hypertension. This review article reviews the recent progress in the research and development of natural lead compounds with antihypertensive activity, including alkaloids, diterpenes, coumarins, flavonoids, and peptides. We summarized their structures, sources, as well as the antihypertensive mechanisms. These information provides instructive reference for the following structural modifications and optimization. PMID:26481372

  18. Use of spike triggered averaging of muscle activity to quantify inputs to motoneuron pools.

    PubMed

    Fortier, P A

    1994-07-01

    1. The goal of this study was to determine the extent to which postspike facilitation (PSpF) of electromyograms (EMGs) could be used to estimate the inputs to separate motoneuron pools, under conditions where there was wide variability in the parameters of muscle activity. These parameters included cancellation of motor unit action potentials (MUAPs), variations in EMG noise, and changes in MUAP amplitude and duration. A systematic series of computer simulations with increasing complexity were used to achieve this goal. The initial simulations (model I) included a premotoneuronal (PreM) cell connected to a single postsynaptic motoneuron (Mn), which in turn projected to a muscle. The next simulations (model II) included other target motoneurons with their efferents each projecting to separate muscles. The last simulations (model III) included more than one postsynaptic motoneuron per Mn-pool, as is the case in mammalian neuromuscular systems. 2. A sample simulation (model I) was performed to determine if the PreM-evoked effects were within physiologically observed values. A cross-correlogram (XC) calculated from a PreM cell and its target Mn, receiving a PreM-evoked excitatory postsynaptic potential (EPSP) of 0.5 mV, produced a XC peak area of 0.04 Mn-spikes/PreM-trigger. The PSpF of EMG activity evoked by this PreM cell had a mean percent increase of 4.6% (MPI = mean bin amplitude of PSpF above baseline/mean baseline level x 100). These XC and PSpF values were within the range of values previously obtained from animal experiments. 3. The magnitude of MUAP cancellation in the EMG was tested by calculating two spike-triggered averages (SpTAs) of EMGs from Mn-triggers (not PreM-triggers as in the other SpTAs): one using typical bipolar MUAPs and another using their rectified counterpart of only positive polarity to eliminate the possibility of MUAP cancellation. The PSpF calculated from bipolar spikes was 24.8% smaller than the one calculated using unipolar spikes

  19. [Current animal feeds with antimicrobial activity].

    PubMed

    Drumev, D

    1981-01-01

    Among the growth-promoting substances and factors contributing to fodder utilization in growing farm animals, also called nutritive, ergotropic means, the antibiotics and some synthetic chemotherapeutics have acquired special importance. To avoid the hazardous effect in humans consuming products of animal origin there should be no residual amounts of these stimulating agents in such products. That is why it has been assumed in a number of countries to use for the same purpose only nutritive means that are not applied as therapeutic agents. Such means should neither induce resistence to antibiotics and chemotherapeutics in microorganism nor should they be resorbed by the alimentary tract (or resorption should be negligible) or they are rapidly eliminated from the animal body, leaving no residual amounts. They should likewise act chiefly against gram-positive organisms, inducing no allergic reactions in the animals. Described are the following nutritive antibiotics: flavophospholipol (bambermycin, menomycin--flavomycin, producing a nutritive effect also in ruminants with a developed forestomach, and rebuilds sensitivity in antibiotic-resistant organisms belonging to Enterobacteriaceae), avoparcin (avotan--also active in ruminants with a developed forestomach), virginiamycin (staphylomycin--escalin, stafac), zincbacitracin (bacipharmin, baciferm), grisin (kormogrisin, of a road spectrum, with an antimycotic effect, raising the fertilization rate and activating phagocitosis), vitamycin-A (vitamycin--active also at retinol deficiency, lambdamycin, nosiheptide (primofax), efrotomycin. Due consideration is given to such chemotherapeutics as nitrovin (payson, paison), carbadox (mecadox, fortigro, of a broad spectrum retained for a longer period in the body of pigs), olaquindox (bio-N-celbar--of a broad spectrum, particularly with regard to gram-negative organisms, applied at present as a therapeutic and prophylactic preparation), cyadox (with a broad sprectrum). The

  20. A voltage-activated proton current in human cardiac fibroblasts

    SciTech Connect

    El Chemaly, Antoun; Guinamard, Romain; Demion, Marie; Fares, Nassim; Jebara, Victor; Faivre, Jean-Francois; Bois, Patrick . E-mail: patrick.bois@univ-poitiers.fr

    2006-02-10

    A voltage-activated proton current in human cardiac fibroblasts, measured using the whole-cell recording configuration of the patch-clamp technique, is reported. Increasing the pH of the bathing solution shifted the current activation threshold to more negative potentials and increased both the current amplitude and its rate of activation. Changing the pH gradient by one unit caused a 51 mV shift in the reversal potential of the current, demonstrating a high selectivity for protons of the channel carrying the current. Extracellularly applied Zn{sup 2+} reversibly inhibited the current. Activation of the current contributes to the resting membrane conductance under conditions of intracellular acidosis. It is proposed that this current in cardiac fibroblasts is involved in the regulation of the intracellular pH and the membrane potential under physiological conditions as well as in response to pathological conditions such as ischemia.

  1. Solutions Network Formulation Report. Improving NOAA's Tides and Currents Through Enhanced Data Inputs from NASA's Ocean Surface Topography Mission

    NASA Technical Reports Server (NTRS)

    Guest, DeNeice C.

    2006-01-01

    The Nation uses water-level data for a variety of practical purposes, including hydrography, nautical charting, maritime navigation, coastal engineering, and tsunami and storm surge warnings (NOAA, 2002; Digby et al., 1999). Long-term applications include marine boundary determinations, tidal predictions, sea-level trend monitoring, oceanographic research, and climate research. Accurate and timely information concerning sea-level height, tide, and ocean current is needed to understand their impact on coastal management, disaster management, and public health. Satellite altimeter data products are currently used by hundreds of researchers and operational users to monitor ocean circulation and to improve scientists understanding of the role of the oceans in climate and weather. The NOAA (National Oceanic and Atmospheric Administration) National Ocean Service has been monitoring sea-level variations for many years (NOAA, 2006). NOAA s Tides & Currents DST (decision support tool, managed by the Center for Operational Oceanographic Products and Services, is the portal to a vast collection of oceanographic and meteorological data (historical and real-time), predictions, and nowcasts and forecasts. This report assesses the capacity of NASA s satellite altimeter data to meet societal decision support needs through incorporation into NOAA s Tides & Currents.

  2. Dopaminergic Modulation of Lateral Amygdala Neuronal Activity: Differential D1 and D2 Receptor Effects on Thalamic and Cortical Afferent Inputs

    PubMed Central

    Grace, Anthony A

    2015-01-01

    Background: In auditory fear conditioning, the lateral nucleus of the amygdala (LA) integrates a conditioned stimulus (CS) from the auditory thalamus (MGN) and the auditory association cortex (Te3) with an aversive unconditioned stimulus. The thalamic input provides a basic version of the CS, while the cortical input provides a processed representation of the stimulus. Dopamine (DA) is released in the LA under heightened arousal during the presentation of the CS. Methods: In this study we examined how D1 or D2 receptor activation affects LA afferent-driven neuronal firing using in vivo extracellular single-unit recordings with local micro-iontophoretic drug application in anesthetized rats. LA neurons that were responsive (~50%) to electrical stimulation in either the MGN or the Te3 were tested by iontophoresis of either the D1 agonist, SKF38393, or the D2 agonist, quinpirole. Results: We found that most of the LA projection neurons exhibited either facilitatory or attenuating effects (changes in evoked probability >15% relative to baseline) on afferent input by activation of D1 or D2 receptors. In general, it required significantly higher stimulation current to evoke ~50% baseline responses to the cortical input. Activation of the D1 receptor showed no difference in modulation between the thalamic or cortical pathways. On the other hand, activation of the D2 receptor had a stronger inhibitory modulation of the cortical pathway, but a stronger excitatory modulation of the thalamic pathway. Conclusions: Our results suggest that there is a shift in balance favoring the thalamic pathway in response to DA acting via the D2 receptor. PMID:25716776

  3. Overexpression of angiotensin-converting enzyme 2 attenuates tonically active glutamatergic input to the rostral ventrolateral medulla in hypertensive rats

    PubMed Central

    Wang, Yang-Kai; Shen, Du; Hao, Qiang; Yu, Qiang; Wu, Zhao-Tang; Deng, Yu; Chen, Yan-Fang; Yuan, Wen-Jun; Hu, Qi-Kuan; Su, Ding-Feng

    2014-01-01

    The rostral ventrolateral medulla (RVLM) plays a key role in cardiovascular regulation. It has been reported that tonically active glutamatergic input to the RVLM is increased in hypertensive rats, whereas angiotensin-converting enzyme 2 (ACE2) in the brain has been suggested to be beneficial to hypertension. This study was designed to determine the effect of ACE2 gene transfer into the RVLM on tonically active glutamatergic input in spontaneously hypertensive rats (SHRs). Lentiviral particles containing enhanced green fluorescent protein (lenti-GFP) or ACE2 (lenti-ACE2) were injected bilaterally into the RVLM. Both protein expression and activity of ACE2 in the RVLM were increased in SHRs after overexpression of ACE2. A significant reduction in blood pressure and heart rate in SHRs was observed 6 wk after lenti-ACE2 injected into the RVLM. The concentration of glutamate in microdialysis fluid from the RVLM was significantly reduced by an average of 61% in SHRs with lenti-ACE2 compared with lenti-GFP. ACE2 overexpression significantly attenuated the decrease in blood pressure and renal sympathetic nerve activity evoked by bilateral injection of the glutamate receptor antagonist kynurenic acid (2.7 nmol in 100 nl) into the RVLM in SHRs. Therefore, we suggest that ACE2 overexpression in the RVLM attenuates the enhanced tonically active glutamatergic input in SHRs, which may be an important mechanism underlying the beneficial effect of central ACE2 to hypertension. PMID:24838502

  4. A Low Input Current and Wide Conversion Ratio Buck Regulator with 75% Efficiency for High-Voltage Triboelectric Nanogenerators

    NASA Astrophysics Data System (ADS)

    Luo, Li-Chuan; Bao, De-Chun; Yu, Wu-Qi; Zhang, Zhao-Hua; Ren, Tian-Ling

    2016-01-01

    It is meaningful to research the Triboelectric Nanogenerators (TENG), which can create electricity anywhere and anytime. There are many researches on the structures and materials of TENG to explain the phenomenon that the maximum voltage is stable and the current is increasing. The output voltage of the TENG is high about 180-400 V, and the output current is small about 39 μA, which the electronic devices directly integration of TENG with Li-ion batteries will result in huge energy loss due to the ultrahigh TENG impedance. A novel interface circuit with the high-voltage buck regulator for TENG is introduced firstly in this paper. The interface circuit can transfer the output signal of the TENG into the signal fit to a lithium ion battery. Through the circuit of the buck regulator, the average output voltage is about 4.0 V and the average output current is about 1.12 mA. Further, the reliability and availability for the lithium ion battery and the circuit are discussed. The interface circuit is simulated using the Cadence software and verified through PCB experiment. The buck regulator can achieve 75% efficiency for the High-Voltage TENG. This will lead to a research hot and industrialization applications.

  5. A Low Input Current and Wide Conversion Ratio Buck Regulator with 75% Efficiency for High-Voltage Triboelectric Nanogenerators

    PubMed Central

    Luo, Li-Chuan; Bao, De-Chun; Yu, Wu-Qi; Zhang, Zhao-Hua; Ren, Tian-Ling

    2016-01-01

    It is meaningful to research the Triboelectric Nanogenerators (TENG), which can create electricity anywhere and anytime. There are many researches on the structures and materials of TENG to explain the phenomenon that the maximum voltage is stable and the current is increasing. The output voltage of the TENG is high about 180–400 V, and the output current is small about 39 μA, which the electronic devices directly integration of TENG with Li-ion batteries will result in huge energy loss due to the ultrahigh TENG impedance. A novel interface circuit with the high-voltage buck regulator for TENG is introduced firstly in this paper. The interface circuit can transfer the output signal of the TENG into the signal fit to a lithium ion battery. Through the circuit of the buck regulator, the average output voltage is about 4.0 V and the average output current is about 1.12 mA. Further, the reliability and availability for the lithium ion battery and the circuit are discussed. The interface circuit is simulated using the Cadence software and verified through PCB experiment. The buck regulator can achieve 75% efficiency for the High-Voltage TENG. This will lead to a research hot and industrialization applications. PMID:26781881

  6. A Low Input Current and Wide Conversion Ratio Buck Regulator with 75% Efficiency for High-Voltage Triboelectric Nanogenerators.

    PubMed

    Luo, Li-Chuan; Bao, De-Chun; Yu, Wu-Qi; Zhang, Zhao-Hua; Ren, Tian-Ling

    2016-01-01

    It is meaningful to research the Triboelectric Nanogenerators (TENG), which can create electricity anywhere and anytime. There are many researches on the structures and materials of TENG to explain the phenomenon that the maximum voltage is stable and the current is increasing. The output voltage of the TENG is high about 180-400 V, and the output current is small about 39 μA, which the electronic devices directly integration of TENG with Li-ion batteries will result in huge energy loss due to the ultrahigh TENG impedance. A novel interface circuit with the high-voltage buck regulator for TENG is introduced firstly in this paper. The interface circuit can transfer the output signal of the TENG into the signal fit to a lithium ion battery. Through the circuit of the buck regulator, the average output voltage is about 4.0 V and the average output current is about 1.12 mA. Further, the reliability and availability for the lithium ion battery and the circuit are discussed. The interface circuit is simulated using the Cadence software and verified through PCB experiment. The buck regulator can achieve 75% efficiency for the High-Voltage TENG. This will lead to a research hot and industrialization applications. PMID:26781881

  7. Current overview of Nevada's petroleum activity

    SciTech Connect

    McDaniel, S.B.

    1987-08-01

    The oil industry in Nevada had its origin in August 1907, when Dr. Tibbetts of Washoe Oil and Development, spudded an 1890-ft well in the terraces overlooking the Truckee River, due west of Reno. Continued pioneer exploration led to the 1954 discovery of the Eagle Springs field by Shell Oil Company in Railroad Valley, Nye County, Nevada. By 1984, four additional oil fields were discovered and the number of permits to drill issued by the Nevada Department of Minerals rose to 69 (versus 11 issued in 1983). This phenomenal increase is attributed to the discovery of the Grant Canyon field in Railroad Valley by Northwest Exploration in September 1983. Presently, the 3 Grant Canyon well is one of the most prolific in the lower 48 states. This well has the capacity to flow more than 3000 BOPD from the Devonian Simonson Formation at approximately 4300 ft depth. Two other fields, the Trap Spring and Bacon Flat, are also located in Railroad Valley. The Blackburn field (operated by Amoco Production Company) also has prolific reef production from the Devonian Nevada Formation. This field is located in Pine Valley, Eureka County, Nevada. Although the present rig count is low, owing to world economics, Nevada's vast frontier potential continues to merit consideration as a major exploration target area for the late 1980s. Nevada had a peak production of 3.04 million barrels of oil in 1985. Future activity is expected to surpass this figure.

  8. Activation and integration of bilateral GABA-mediated synaptic inputs in neonatal rat sympathetic preganglionic neurones in vitro

    PubMed Central

    Whyment, Andrew D; Wilson, Jennifer M M; Renaud, Leo P; Spanswick, David

    2004-01-01

    The role of GABA receptors in synaptic transmission to neonatal rat sympathetic preganglionic neurones (SPNs) was investigated utilizing whole-cell patch clamp recording techniques in longitudinal and transverse spinal cord slice preparations. In the presence of glutamate receptor antagonists (NBQX, 5 μm and D-APV, 10 μm), electrical stimulation of the ipsilateral or contralateral lateral funiculi (iLF and cLF, respectively) revealed monosynaptic inhibitory postsynaptic potentials (IPSPs) in 75% and 65% of SPNs, respectively. IPSPs were sensitive to bicuculline (10 μm) in all neurones tested and reversed polarity around −55 mV, the latter indicating mediation via chloride conductances. In three neurones IPSPs evoked by stimulation of the iLF (n = 1) or cLF (n = 2) were partly sensitive to strychnine (2 μm). The expression of postsynaptic GABAA and GABAB receptors were confirmed by the sensitivity of SPNs to agonists, GABA (2 mm), muscimol (10–100 μm) or baclofen (10–100 μm), in the presence of TTX, each of which produced membrane hyperpolarization in all SPNs tested. Muscimol-induced responses were sensitive to bicuculline (1–10 μm) and SR95531 (10 μm) and baclofen-induced responses were sensitive to 2-hydroxy-saclofen (100–200 μm) and CGP55845 (200 nm). The GABAC receptor agonist CACA (200 μm) was without significant effect on SPNs. These results suggest that SPNs possess postsynaptic GABAA and GABAB receptors and that subsets of SPNs receive bilateral GABAergic inputs which activate GABAA receptors, coupled to a chloride conductance. At resting or holding potentials close to threshold either single or bursts (10–100 Hz) of IPSPs gave rise to a rebound excitation and action potential firing at the termination of the burst. This effect was mimicked by injection of small (10–20 pA) rectangular-wave current pulses, which revealed a time-dependent, Cs+-sensitive inward rectification and rebound excitation at the termination of the response to

  9. State, Parameter, and Unknown Input Estimation Problems in Active Automotive Safety Applications

    NASA Astrophysics Data System (ADS)

    Phanomchoeng, Gridsada

    A variety of driver assistance systems such as traction control, electronic stability control (ESC), rollover prevention and lane departure avoidance systems are being developed by automotive manufacturers to reduce driver burden, partially automate normal driving operations, and reduce accidents. The effectiveness of these driver assistance systems can be significant enhanced if the real-time values of several vehicle parameters and state variables, namely tire-road friction coefficient, slip angle, roll angle, and rollover index, can be known. Since there are no inexpensive sensors available to measure these variables, it is necessary to estimate them. However, due to the significant nonlinear dynamics in a vehicle, due to unknown and changing plant parameters, and due to the presence of unknown input disturbances, the design of estimation algorithms for this application is challenging. This dissertation develops a new approach to observer design for nonlinear systems in which the nonlinearity has a globally (or locally) bounded Jacobian. The developed approach utilizes a modified version of the mean value theorem to express the nonlinearity in the estimation error dynamics as a convex combination of known matrices with time varying coefficients. The observer gains are then obtained by solving linear matrix inequalities (LMIs). A number of illustrative examples are presented to show that the developed approach is less conservative and more useful than the standard Lipschitz assumption based nonlinear observer. The developed nonlinear observer is utilized for estimation of slip angle, longitudinal vehicle velocity, and vehicle roll angle. In order to predict and prevent vehicle rollovers in tripped situations, it is necessary to estimate the vertical tire forces in the presence of unknown road disturbance inputs. An approach to estimate unknown disturbance inputs in nonlinear systems using dynamic model inversion and a modified version of the mean value theorem is

  10. DISTRIBUTION OF ELECTRIC CURRENTS IN SOLAR ACTIVE REGIONS

    SciTech Connect

    Török, T.; Titov, V. S.; Mikić, Z.; Leake, J. E.; Archontis, V.; Linton, M. G.; Dalmasse, K.; Aulanier, G.; Kliem, B.

    2014-02-10

    There has been a long-standing debate on the question of whether or not electric currents in solar active regions are neutralized. That is, whether or not the main (or direct) coronal currents connecting the active region polarities are surrounded by shielding (or return) currents of equal total value and opposite direction. Both theory and observations are not yet fully conclusive regarding this question, and numerical simulations have, surprisingly, barely been used to address it. Here we quantify the evolution of electric currents during the formation of a bipolar active region by considering a three-dimensional magnetohydrodynamic simulation of the emergence of a sub-photospheric, current-neutralized magnetic flux rope into the solar atmosphere. We find that a strong deviation from current neutralization develops simultaneously with the onset of significant flux emergence into the corona, accompanied by the development of substantial magnetic shear along the active region's polarity inversion line. After the region has formed and flux emergence has ceased, the strong magnetic fields in the region's center are connected solely by direct currents, and the total direct current is several times larger than the total return current. These results suggest that active regions, the main sources of coronal mass ejections and flares, are born with substantial net currents, in agreement with recent observations. Furthermore, they support eruption models that employ pre-eruption magnetic fields containing such currents.

  11. Active vibration control of Flexible Joint Manipulator using Input Shaping and Adaptive Parameter Auto Disturbance Rejection Controller

    NASA Astrophysics Data System (ADS)

    Li, W. P.; Luo, B.; Huang, H.

    2016-02-01

    This paper presents a vibration control strategy for a two-link Flexible Joint Manipulator (FJM) with a Hexapod Active Manipulator (HAM). A dynamic model of the multi-body, rigid-flexible system composed of an FJM, a HAM and a spacecraft was built. A hybrid controller was proposed by combining the Input Shaping (IS) technique with an Adaptive-Parameter Auto Disturbance Rejection Controller (APADRC). The controller was used to suppress the vibration caused by external disturbances and input motions. Parameters of the APADRC were adaptively adjusted to ensure the characteristic of the closed loop system to be a given reference system, even if the configuration of the manipulator significantly changes during motion. Because precise parameters of the flexible manipulator are not required in the IS system, the operation of the controller was sufficiently robust to accommodate uncertainties in system parameters. Simulations results verified the effectiveness of the HAM scheme and controller in the vibration suppression of FJM during operation.

  12. Micropower non-contact EEG electrode with active common-mode noise suppression and input capacitance cancellation.

    PubMed

    Chi, Yu M; Cauwenberghs, Gert

    2009-01-01

    A non-contact EEG electrode with input capacitance neutralization and common-mode noise suppression circuits is presented. The coin sized sensor capacitively couples to the scalp without direct contact to the skin. To minimize the effect of signal attenuation and channel gain mismatch, the input capacitance of each sensor is actively neutralized using positive feedback and bootstrapping. Common-mode suppression is achieved through a single conductive sheet to establish a common mode reference. Each sensor electrode provides a differential gain of 60 dB. Signals are transmitted in a digital serial daisy-chain directly from a local 16-bit ADC, minimizing the number of wires required to establish a high density EEG sensor network. The micropower electrode consumes only 600 microW from a single 3.3 V supply. PMID:19964104

  13. Enhancement of signal-to-noise ratio and phase locking for small inputs by a low-threshold outward current in auditory neurons.

    PubMed

    Svirskis, Gytis; Kotak, Vibhakar; Sanes, Dan H; Rinzel, John

    2002-12-15

    Neurons possess multiple voltage-dependent conductances specific for their function. To investigate how low-threshold outward currents improve the detection of small signals in a noisy background, we recorded from gerbil medial superior olivary (MSO) neurons in vitro. MSO neurons responded phasically, with a single spike to a step current injection. When bathed in dendrotoxin (DTX), most cells switched to tonic firing, suggesting that low-threshold potassium currents (I(KLT)) participated in shaping these phasic responses. Neurons were stimulated with a computer-generated steady barrage of random inputs, mimicking weak synaptic conductance transients (the "noise"), together with a larger but still subthreshold postsynaptic conductance, EPSG (the "signal"). DTX reduced the signal-to-noise ratio (SNR), defined as the ratio of probability to fire in response to the EPSG and the probability to fire spontaneously in response to noise. The reduction was mainly attributable to the increase of spontaneous firing in DTX. The spike-triggered reverse correlation indicated that, for spike generation, the neuron with I(KLT) required faster inward current transients. This narrow temporal integration window contributed to superior phase locking of firing to periodic stimuli before application of DTX. A computer model including Hodgkin-Huxley type conductances for spike generation and for I(KLT) (Rathouz and Trussell, 1998) showed similar response statistics. The dynamic low-threshold outward current increased SNR and the temporal precision of integration of weak subthreshold signals in auditory neurons by suppressing false positives. PMID:12486197

  14. Icing Branch Current Research Activities in Icing Physics

    NASA Technical Reports Server (NTRS)

    Vargas, Mario

    2009-01-01

    Current development: A grid block transformation scheme which allows the input of grids in arbitrary reference frames, the use of mirror planes, and grids with relative velocities has been developed. A simple ice crystal and sand particle bouncing scheme has been included. Added an SLD splashing model based on that developed by William Wright for the LEWICE 3.2.2 software. A new area based collection efficiency algorithm will be incorporated which calculates trajectories from inflow block boundaries to outflow block boundaries. This method will be used for calculating and passing collection efficiency data between blade rows for turbo-machinery calculations.

  15. Biological Ocean Margins Program. Active Microbes Responding to Inputs from the Orinoco River Plume. Final Report

    SciTech Connect

    Jorge E. Corredor

    2013-01-28

    The overall goal of the proposed work is to identify the active members of the heterotrophic community involved in C and N cycling in the perimeter of the Orinoco River Plume (ORP), assess their spatial distribution, quantify their metabolic activity, and correlate these parameters to plume properties such as salinity, organic matter content and phytoplankton biomass.

  16. Explorations of electric current system in solar active regions. I - Empirical inferences of the current flows

    NASA Technical Reports Server (NTRS)

    Ding, Y. J.; Hong, Q. F.; Hagyard, M. J.; Deloach, A. C.; Liu, X. P.

    1987-01-01

    Techniques to identify sources of electric current systems and their channels of flow in solar active regions are explored. Measured photospheric vector magnetic fields together with high-resolution white-light and H-alpha filtergrams provide the data base to derive the current systems in the photosphere and chromosphere. As an example, the techniques are then applied to infer current systems in AR 2372 in early April 1980.

  17. Microbial dynamics and enzyme activities in tropical Andosols depending on land use and nutrient inputs

    NASA Astrophysics Data System (ADS)

    Mganga, Kevin; Razavi, Bahar; Kuzyakov, Yakov

    2015-04-01

    Microbial decomposition of soil organic matter is mediated by enzymes and is a key source of terrestrial CO2 emissions. Microbial and enzyme activities are necessary to understand soil biochemical functioning and identify changes in soil quality. However, little is known about land use and nutrients availability effects on enzyme activities and microbial processes, especially in tropical soils of Africa. This study was conducted to examine how microbial and enzyme activities differ between different land uses and nutrient availability. As Andosols of Mt. Kilimanjaro are limited by nutrient concentrations, we hypothesize that N and P additions will stimulate enzyme activity. N and P were added to soil samples (0-20 cm) representing common land use types in East Africa: (1) savannah, (2) maize fields, (3) lower montane forest, (4) coffee plantation, (5) grasslands and (6) traditional Chagga homegardens. Total CO2 efflux from soil, microbial biomass and activities of β-glucosidase, cellobiohydrolase, chitinase and phosphatase involved in C, N and P cycling, respectively was monitored for 60 days. Total CO2 production, microbial biomass and enzyme activities varied in the order forest soils > grassland soils > arable soils. Increased β-glucosidase and cellobiohydrolase activities after N addition of grassland soils suggest that microorganisms increased N uptake and utilization to produce C-acquiring enzymes. Low N concentration in all soils inhibited chitinase activity. Depending on land use, N and P addition had an inhibitory or neutral effect on phosphatase activity. We attribute this to the high P retention of Andosols and low impact of N and P on the labile P fractions. Enhanced CO2 production after P addition suggests that increased P availability could stimulate soil organic matter biodegradation in Andosols. In conclusion, land use and nutrients influenced soil enzyme activities and microbial dynamics and demonstrated the decline in soil quality after landuse

  18. Direct Ventral Hippocampal-Prefrontal Input Is Required for Anxiety-Related Neural Activity and Behavior.

    PubMed

    Padilla-Coreano, Nancy; Bolkan, Scott S; Pierce, Georgia M; Blackman, Dakota R; Hardin, William D; Garcia-Garcia, Alvaro L; Spellman, Timothy J; Gordon, Joshua A

    2016-02-17

    The ventral hippocampus (vHPC), medial prefrontal cortex (mPFC), and basolateral amygdala (BLA) are each required for the expression of anxiety-like behavior. Yet the role of each individual element of the circuit is unclear. The projection from the vHPC to the mPFC has been implicated in anxiety-related neural synchrony and spatial representations of aversion. The role of this projection was examined using multi-site neural recordings combined with optogenetic terminal inhibition. Inhibition of vHPC input to the mPFC disrupted anxiety and mPFC representations of aversion, and reduced theta synchrony in a pathway-, frequency- and task-specific manner. Moreover, bilateral, but not unilateral, inhibition altered physiological correlates of anxiety in the BLA, mimicking a safety-like state. These results reveal a specific role for the vHPC-mPFC projection in anxiety-related behavior and the spatial representation of aversive information within the mPFC. PMID:26853301

  19. Soil Microbe Active Community Composition and Capability of Responding to Litter Addition after 12 Years of No Inputs

    PubMed Central

    Brewer, Elizabeth; Yarwood, Rockie; Lajtha, Kate; Myrold, David

    2013-01-01

    One explanation given for the high microbial diversity found in soils is that they contain a large inactive biomass that is able to persist in soils for long periods of time. This persistent microbial fraction may help to buffer the functionality of the soil community during times of low nutrients by providing a reservoir of specialized functions that can be reactivated when conditions improve. A study was designed to test the hypothesis: in soils lacking fresh root or detrital inputs, microbial community composition may persist relatively unchanged. Upon addition of new inputs, this community will be stimulated to grow and break down litter similarly to control soils. Soils from two of the Detrital Input and Removal Treatments (DIRT) at the H. J. Andrews Experimental Forest, the no-input and control treatment plots, were used in a microcosm experiment where Douglas-fir needles were added to soils. After 3 and 151 days of incubation, soil microbial DNA and RNA was extracted and characterized using quantitative PCR (qPCR) and 454 pyrosequencing. The abundance of 16S and 28S gene copies and RNA copies did not vary with soil type or amendment; however, treatment differences were observed in the abundance of archaeal ammonia-oxidizing amoA gene abundance. Analysis of ∼110,000 bacterial sequences showed a significant change in the active (RNA-based) community between day 3 and day 151, but microbial composition was similar between soil types. These results show that even after 12 years of plant litter exclusion, the legacy of community composition was well buffered against a dramatic disturbance. PMID:23263952

  20. An 11 μ w, two-electrode transimpedance biosignal amplifier with active current feedback stabilization.

    PubMed

    Inan, O T; Kovacs, G T A

    2010-04-01

    A novel two-electrode biosignal amplifier circuit is demonstrated by using a composite transimpedance amplifier input stage with active current feedback. Micropower, low gain-bandwidth product operational amplifiers can be used, leading to the lowest reported overall power consumption in the literature for a design implemented with off-the-shelf commercial integrated circuits (11 μW). Active current feedback forces the common-mode input voltage to stay within the supply rails, reducing baseline drift and amplifier saturation problems that can be present in two-electrode systems. The bandwidth of the amplifier extends from 0.05-200 Hz and the midband voltage gain (assuming an electrode-to-skin resistance of 100 kΩ) is 48 dB. The measured output noise level is 1.2 mV pp, corresponding to a voltage signal-to-noise ratio approaching 50 dB for a typical electrocardiogram (ECG) level input of 1 mVpp. Recordings were taken from a subject by using the proposed two-electrode circuit and, simultaneously, a three-electrode standard ECG circuit. The residual of the normalized ensemble averages for both measurements was computed, and the power of this residual was 0.54% of the power of the standard ECG measurement output. While this paper primarily focuses on ECG applications, the circuit can also be used for amplifying other biosignals, such as the electroencephalogram. PMID:23853316

  1. Both barium and calcium activate neuronal potassium currents.

    PubMed Central

    Ribera, A B; Spitzer, N C

    1987-01-01

    Amphibian spinal neurons in culture possess both rapidly inactivating and sustained calcium-dependent potassium current components, similar to those described for other cells. Divalent cation-dependent whole-cell outward currents were isolated by subtracting the voltage-dependent potassium currents recorded from Xenopus laevis neurons in the presence of impermeant cadmium (100-500 microM) from the currents produced without cadmium but in the presence of permeant divalent cations (50-100 microM). These concentrations of permeant ions were low enough to avoid contamination by macroscopic inward currents through calcium channels. Calcium-dependent potassium currents were reduced by 1 microM tetraethylammonium. These currents can also be activated by barium or strontium. Barium as well as calcium activated outward currents in young neurons (6-8 hr) and in relatively mature neurons (19-26 hr in vitro). However, barium influx appeared to suppress the sustained voltage-dependent potassium current in most cells. Barium also activated at least one class of potassium channels observed in excised membrane patches, while blocking others. The blocking action may have masked and hindered detection of the stimulatory action of barium in other systems. PMID:2442762

  2. The optimization of force inputs for active structural acoustic control using a neural network

    NASA Technical Reports Server (NTRS)

    Cabell, R. H.; Lester, H. C.; Silcox, R. J.

    1992-01-01

    This paper investigates the use of a neural network to determine which force actuators, of a multi-actuator array, are best activated in order to achieve structural-acoustic control. The concept is demonstrated using a cylinder/cavity model on which the control forces, produced by piezoelectric actuators, are applied with the objective of reducing the interior noise. A two-layer neural network is employed and the back propagation solution is compared with the results calculated by a conventional, least-squares optimization analysis. The ability of the neural network to accurately and efficiently control actuator activation for interior noise reduction is demonstrated.

  3. EVALUATION OF ESTROGENIC ACTIVITY FROM A MUNICIPAL WASTEWATER TREATMENT PLANT WITH PREDOMINANTLY DOMESTIC INPUT

    EPA Science Inventory

    The purpose of this study was to survey estrogenic releases from two primarily domestic wastewater treatment plants over three seasons (1996-1999). Mature male channel catfish were maintained at two sites within each WWTP and a reference site for 21 days. Estrogenic activity of e...

  4. A Newly Identified Extrinsic Input Triggers a Distinct Gastric Mill Rhythm via Activation of Modulatory Projection Neurons

    PubMed Central

    Blitz, Dawn M.; White, Rachel S.; Saideman, Shari R.; Cook, Aaron; Christie, Andrew E.; Nadim, Farzan; Nusbaum, Michael P.

    2008-01-01

    Neuronal network flexibility enables animals to respond appropriately to changes in their internal and external states. We are using the isolated crab stomatogastric nervous system to determine how extrinsic inputs contribute to network flexibility. The stomatogastric system includes the well-characterized gastric mill (chewing) and pyloric (filtering of chewed food) motor circuits in the stomatogastric ganglion. Projection neurons with somata in the commissural ganglia (CoGs) regulate these rhythms. Previous work characterized a unique gastric mill rhythm that occurred spontaneously in some preparations, but whose origin remained undetermined. This rhythm includes a distinct protractor phase activity pattern, during which all active gastric mill circuit and projection neurons fire in a pyloric rhythm-timed activity pattern instead of the tonic firing pattern exhibited by these neurons during previously studied gastric mill rhythms. Here we identify a new extrinsic input, the post-oesophageal commissure (POC) neurons, relatively brief stimulation (30 sec) of which triggers a long-lasting (tens of minutes) activation of this novel gastric mill rhythm at least in part via its lasting activation of CoG projection neurons, including the previously identified MCN1 and CPN2. Immunocytochemical and electrophysiological data suggest that the POC neurons excite MCN1 and CPN2 by release of the neuropeptide Cancer borealis tachykinin-related peptide Ia (CabTRP Ia). These data further suggest that the CoG arborization of the POC neurons comprises the previously identified anterior commissural organ (ACO), a CabTRP Ia-containing neurohemal organ. This endocrine pathway thus appears to also have paracrine actions that include activation of a novel and lasting gastric mill rhythm. PMID:18310125

  5. Boost of plasma current with active magnetic field shaping coils in rotamak discharges

    SciTech Connect

    Yang Xiaokang; Goss, Jermain; Kalaria, Dhara; Huang, Tian Sen

    2011-08-15

    A set of magnetic shaping coils is installed on the Prairie View (PV) rotamak for the study of active plasma shape control in the regimes with and without toroidal field (TF). In the spherical tokamak regime (with TF), plasma current I{sub p} can be boosted by 200% when all five shaping coils (connected in series) are energized. The enhancement of current drive efficiency is mainly attributed to the radial compression and the substantially axial extension of the plasma column; this in turn improves the impedance matching and thus increases antenna input power. In the field-reversed configuration (without TF), plasma current can be boosted by 100% when one middle coil is used; the appearance of radial shift mode limits the achievable value of I{sub p}. The experiments clearly demonstrate that the plasma shape control plays a role in effectively driving plasma current in rotamaks.

  6. Rapid and continuous activity-dependent plasticity of olfactory sensory input

    PubMed Central

    Cheetham, Claire E. J.; Park, Una; Belluscio, Leonardo

    2016-01-01

    Incorporation of new neurons enables plasticity and repair of circuits in the adult brain. Adult neurogenesis is a key feature of the mammalian olfactory system, with new olfactory sensory neurons (OSNs) wiring into highly organized olfactory bulb (OB) circuits throughout life. However, neither when new postnatally generated OSNs first form synapses nor whether OSNs retain the capacity for synaptogenesis once mature, is known. Therefore, how integration of adult-born OSNs may contribute to lifelong OB plasticity is unclear. Here, we use a combination of electron microscopy, optogenetic activation and in vivo time-lapse imaging to show that newly generated OSNs form highly dynamic synapses and are capable of eliciting robust stimulus-locked firing of neurons in the mouse OB. Furthermore, we demonstrate that mature OSN axons undergo continuous activity-dependent synaptic remodelling that persists into adulthood. OSN synaptogenesis, therefore, provides a sustained potential for OB plasticity and repair that is much faster than OSN replacement alone. PMID:26898529

  7. Inferred flows of electric currents in solar active regions

    NASA Technical Reports Server (NTRS)

    Ding, Y. J.; Hong, Q. F.; Hagyard, M. J.; Deloach, A. C.

    1985-01-01

    Techniques to identify sources of major current systems in active regions and their channels of flow are explored. Measured photospheric vector magnetic fields together with high resolution white light and H-alpha photographs provide the data base to derive the current systems in the photosphere and chromosphere of a solar active region. Simple mathematical constructions of active region fields and currents are used to interpret these data under the assumptions that the fields in the lower atmosphere (below 200 km) may not be force free but those in the chromosphere and higher are. The results obtained for the complex active region AR 2372 are: (1) Spots exhibiting significant spiral structure in the penumbral filaments were the source of vertical currents at the photospheric surface; (2) Magnetic neutral lines where the transverse magnetic field was strongly sheared were channels along which a strong current system flowed; (3) The inferred current systems produced a neutral sheet and oppositely-flowing currents in the area of the magnetic delta configuration that was the site of flaring.

  8. Modulation of C-nociceptive Activities by Inputs from Myelinated Fibers.

    PubMed

    Wan-Ru, Duan; Yi-Kuan, Xie

    2016-01-01

    To understand the mechanisms of neuropathic pain caused by demyelination, a rapid-onset, completed but reversible demyelination of peripheral A-fibers and neuropathic pain behaviors in adult rats by single injection of cobra venom into the sciatic nerve, was created. Microfilament recording revealed that cobra venom selectively blocked A-fibers, but not C-fibers. Selective blockade of A-fibers may result from A-fiber demyelination at the site of venom injection as demonstrated by microscope examination. Neuropathic pain behaviors including inflammatory response appeared almost immediately after venom injection and lasted about 3 weeks. Electrophysiological studies indicated that venom injection induced loss of conduction in A-fibers, increased sensitivity of C-polymodal nociceptors to innocuous stimuli, and triggered spontaneous activity from peripheral and central terminals of C-fiber nociceptors. Neurogenic inflammatory responses were also observed in the affected skin via Evans blue extravasation experiments. Both antidromic C-fiber spontaneous activity and neurogenic inflammation were substantially decreased by continuous A-fiber threshold electric stimuli applied proximally to the venom injection site. The data suggest that normal activity of peripheral A-fibers may produce inhibitory modulation of C-polymodal nociceptors. Removal of inhibition to C-fiber polymodal nociceptors following demyelination of A-fibers may result in pain and neurogenic inflammation in the affected receptive field. PMID:26900061

  9. A hyperpolarization-activated ion current of amphibian oocytes.

    PubMed

    Ochoa-de la Paz, L D; Salazar-Soto, D B; Reyes, J P; Miledi, R; Martinez-Torres, A

    2013-08-01

    A comparative analysis of a hyperpolarization-activated ion current present in amphibian oocytes was performed using the two-electrode voltage-clamp technique in Xenopus laevis, Xenopus tropicalis, and Ambystoma mexicanum. This current appears to be driven mainly by Cl(-) ions, is independent of Ca(2+), and is made evident by applying extremely negative voltage pulses; it shows a slow activating phase and little or no desensitization. The pharmacological profile of the current is complex. The different channel blocker used for Cl(-), K(+), Na(+) and Ca(2+) conductances, exhibited various degrees of inhibition depending of the species. The profiles illustrate the intricacy of the components that give rise to this current. During X. laevis oogenesis, the hyperpolarization-activated current is present at all stages of oocytes tested (II-VI), and the amplitude of the current increases from about 50 nA in stage I to more than 1 μA in stage VI; nevertheless, there was no apparent modification of the kinetics. Our results suggest that the hyperpolarization-activated current is present both in order Anura and Urodela oocytes. However, the electrophysiological and pharmacological characteristics are quite perplexing and seem to suggest a mixture of ionic conductances that includes the activation of both anionic and cationic channels, most probably transiently opened due to the extreme hyperpolarizion of the plasma membrane. As a possible mechanism for the generation of the current, a kinetic model which fits the data suggests the opening of pores in the plasma membrane whose ion selectivity is dependent on the extracellular Cl(-) concentration. The extreme voltage conditions could induce the opening of otherwise latent pores in plasma membrane proteins (i.e., carriers), resembling the ´slippage´ events already described for some carriers. These observations should be valuable for other groups trying to express cloned, voltage-dependent ion channels in oocytes of

  10. Human cervical spinal cord circuitry activated by tonic input can generate rhythmic arm movements.

    PubMed

    Solopova, I A; Selionov, V A; Zhvansky, D S; Gurfinkel, V S; Ivanenko, Y

    2016-02-01

    The coordination between arms and legs during human locomotion shares many features with that in quadrupeds, yet there is limited evidence for the central pattern generator for the upper limbs in humans. Here we investigated whether different types of tonic stimulation, previously used for eliciting stepping-like leg movements, may evoke nonvoluntary rhythmic arm movements. Twenty healthy subjects participated in this study. The subject was lying on the side, the trunk was fixed, and all four limbs were suspended in a gravity neutral position, allowing unrestricted low-friction limb movements in the horizontal plane. The results showed that peripheral sensory stimulation (continuous muscle vibration) and central tonic activation (postcontraction state of neuronal networks following a long-lasting isometric voluntary effort, Kohnstamm phenomenon) could evoke nonvoluntary rhythmic arm movements in most subjects. In ∼40% of subjects, tonic stimulation elicited nonvoluntary rhythmic arm movements together with rhythmic movements of suspended legs. The fact that not all participants exhibited nonvoluntary limb oscillations may reflect interindividual differences in responsiveness of spinal pattern generation circuitry to its activation. The occurrence and the characteristics of induced movements highlight the rhythmogenesis capacity of cervical neuronal circuitries, complementing the growing body of work on the quadrupedal nature of human gait. PMID:26683072

  11. Ghrelin modulates the activity and synaptic input organization of midbrain dopamine neurons while promoting appetite

    PubMed Central

    Abizaid, Alfonso; Liu, Zhong-Wu; Andrews, Zane B.; Shanabrough, Marya; Borok, Erzsebet; Elsworth, John D.; Roth, Robert H.; Sleeman, Mark W.; Picciotto, Marina R.; Tschöp, Matthias H.; Gao, Xiao-Bing; Horvath, Tamas L.

    2006-01-01

    The gut hormone ghrelin targets the brain to promote food intake and adiposity. The ghrelin receptor growth hormone secretagogue 1 receptor (GHSR) is present in hypothalamic centers controlling energy metabolism as well as in the ventral tegmental area (VTA), a region important for motivational aspects of multiple behaviors, including feeding. Here we show that in mice and rats, ghrelin bound to neurons of the VTA, where it triggered increased dopamine neuronal activity, synapse formation, and dopamine turnover in the nucleus accumbens in a GHSR-dependent manner. Direct VTA administration of ghrelin also triggered feeding, while intra-VTA delivery of a selective GHSR antagonist blocked the orexigenic effect of circulating ghrelin and blunted rebound feeding following fasting. In addition, ghrelin- and GHSR-deficient mice showed attenuated feeding responses to restricted feeding schedules. Taken together, these data suggest that the mesolimbic reward circuitry is targeted by peripheral ghrelin to influence physiological mechanisms related to feeding. PMID:17060947

  12. Active control of sound transmission/radiation from elastic plates by vibration inputs. I - Analysis

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.

    1990-01-01

    Active control of sound radiation from vibrating plates by oscillating forces applied directly to the structure is analytically studied. The model consists of a plane acoustic wave incident on a clamped elastic circular thin plate. Control is achieved by point forces, and quadratic optimization is used to calculate the optimal control gains necessary to minimize a cost function proportional to the radiated acoustic power (the transmitted field). The results show that global attenuation of broadband radiated sound levels for low to mid-range frequencies can be achieved with one or two control forces, irrespective of whether the system is on or off resonance. The efficiency of the control strategy is demonstrated to be related to the nature of the coupling between the plate modes of response and the radiated field.

  13. Pacemaker activity and ionic currents in mouse atrioventricular node cells

    PubMed Central

    Marger, Laurine; Mesirca, Pietro; Alig, Jacqueline; Torrente, Angelo; Dubel, Stefan; Engeland, Birgit; Kanani, Sandra; Fontanaud, Pierre; Striessnig, Jörg; Shin, Hee-Sup; Isbrandt, Dirk; Ehmke, Heimo; Nargeot, Joël

    2011-01-01

    It is well established that pacemaker activity of the sino-atrial node (SAN) initiates the heartbeat. However, the atrioventricular node (AVN) can generate viable pacemaker activity in case of SAN failure, but we have limited knowledge of the ionic bases of AVN automaticity. We characterized pacemaker activity and ionic currents in automatic myocytes of the mouse AVN. Pacemaking of AVN cells (AVNCs) was lower than that of SAN pacemaker cells (SANCs), both in control conditions and upon perfusion of isoproterenol (ISO). Block of INa by tetrodotoxin (TTX) or of ICa,L by isradipine abolished AVNCs pacemaker activity. TTX-resistant (INar) and TTX-sensitive (INas) Na+ currents were recorded in mouse AVNCs, as well as T-(ICa,T) and L-type (ICa,L) Ca2+ currents. ICa,L density was lower than in SANCs (51%). The density of the hyperpolarization-activated current, (If) and that of the fast component of the delayed rectifier current (IKr) were, respectively, lower (52%) and higher (53%) in AVNCs than in SANCs. Pharmacological inhibition of If by 3 µM ZD-7228 reduced pacemaker activity by 16%, suggesting a relevant role for If in AVNCs automaticity. Some AVNCs expressed also moderate densities of the transient outward K+ current (Ito). In contrast, no detectable slow component of the delayed rectifier current (IKs) could be recorded in AVNCs. The lower densities of If and ICa,L, as well as higher expression of IKr in AVNCs than in SANCs may contribute to the intrinsically slower AVNCs pacemaking than that of SANCs. PMID:21406959

  14. CURRENT AND KINETIC HELICITY OF LONG-LIVED ACTIVITY COMPLEXES

    SciTech Connect

    Komm, Rudolf; Gosain, Sanjay

    2015-01-01

    We study long-lived activity complexes and their current helicity at the solar surface and their kinetic helicity below the surface. The current helicity has been determined from synoptic vector magnetograms from the NSO/SOLIS facility, and the kinetic helicity of subsurface flows has been determined with ring-diagram analysis applied to full-disk Dopplergrams from NSO/GONG and SDO/HMI. Current and kinetic helicity of activity complexes follow the hemispheric helicity rule with mainly positive values (78%; 78%, respectively, with a 95% confidence level of 31%) in the southern hemisphere and negative ones (80%; 93%, respectively, with a 95% confidence level of 22% and 14%, respectively) in the northern hemisphere. The locations with the dominant sign of kinetic helicity derived from Global Oscillation Network Group (GONG) and SDO/HMI data are more organized than those of the secondary sign even if they are not part of an activity complex, while locations with the secondary sign are more fragmented. This is the case for both hemispheres even for the northern one where it is not as obvious visually due to the large amount of magnetic activity present as compared to the southern hemisphere. The current helicity shows a similar behavior. The dominant sign of current helicity is the same as that of kinetic helicity for the majority of the activity complexes (83% with a 95% confidence level of 15%). During the 24 Carrington rotations analyzed here, there is at least one longitude in each hemisphere where activity complexes occur repeatedly throughout the epoch. These ''active'' longitudes are identifiable as locations of strong current and kinetic helicity of the same sign.

  15. Optimisation of active suspension control inputs for improved vehicle ride performance

    NASA Astrophysics Data System (ADS)

    Čorić, Mirko; Deur, Joško; Xu, Li; Tseng, H. Eric; Hrovat, Davor

    2016-07-01

    A collocation-type control variable optimisation method is used in the paper to analyse to which extent the fully active suspension (FAS) can improve the vehicle ride comfort while preserving the wheel holding ability. The method is first applied for a cosine-shaped bump road disturbance of different heights, and for both quarter-car and full 10 degree-of-freedom vehicle models. A nonlinear anti-wheel hop constraint is considered, and the influence of bump preview time period is analysed. The analysis is then extended to the case of square- or cosine-shaped pothole with different lengths, and the quarter-car model. In this case, the cost function is extended with FAS energy consumption and wheel damage resilience costs. The FAS action is found to be such to provide a wheel hop over the pothole, in order to avoid or minimise the damage at the pothole trailing edge. In the case of long pothole, when the FAS cannot provide the wheel hop, the wheel is travelling over the pothole bottom and then hops over the pothole trailing edge. The numerical optimisation results are accompanied by a simplified algebraic analysis.

  16. Electric currents and coronal heating in NOAA active region 6952

    NASA Technical Reports Server (NTRS)

    Metcalf, T. R.; Canfield, R. C.; Hudson, H. S.; Mickey, D. L.; Wulser, J. -P.; Martens, P. C. H.; Tsuneta, S.

    1994-01-01

    We examine the spatial and temporal relationship between coronal structures observed with the soft X-ray telescope (SXT) on board the Yohkoh spacecraft and the vertical electric current density derived from photospheric vector magnetograms obtained using the Stokes Polarimeter at the Mees Solar Observatory. We focus on a single active region: AR 6952 which we observed on 7 days during 1991 December. For 11 independent maps of the vertical electric current density co-aligned with non-flaring X-ray images, we search for a morphological relationship between sites of high vertical current density in the photosphere and enhanced X-ray emission in the overlying corona. We find no compelling spatial or temporal correlation between the sites of vertical current and the bright X-ray structures in this active region.

  17. Proton block of proton-activated TRPV1 current

    PubMed Central

    Lee, Bo Hyun

    2015-01-01

    The TRPV1 cation channel is a polymodal nociceptor that is activated by heat and ligands such as capsaicin and is highly sensitive to changes in extracellular pH. In the body core, where temperature is usually stable and capsaicin is normally absent, H+ released in response to ischemia, tissue injury, or inflammation is the best-known endogenous TRPV1 agonist, activating the channel to mediate pain and vasodilation. Paradoxically, removal of H+ elicits a transient increase in TRPV1 current that is much larger than the initial H+-activated current. We found that this prominent OFF response is caused by rapid recovery from H+ inhibition of the excitatory current carried by H+-activated TRPV1 channels. H+ inhibited current by interfering with ion permeation. The degree of inhibition is voltage and permeant ion dependent, and it can be affected but not eliminated by mutations to acidic residues within or near the ion selectivity filter. The opposing H+-mediated gating and permeation effects produce complex current responses under different cellular conditions that are expected to greatly affect the response of nociceptive neurons and other TRPV1-expressing cells. PMID:26170176

  18. Active control of sound radiation from a vibrating rectangular panel by sound sources and vibration inputs - An experimental comparison

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.; Hansen, C. H.; Snyder, S. D.

    1991-01-01

    Active control of sound radiation from a rectangular panel by two different methods has been experimentally studied and compared. In the first method a single control force applied directly to the structure is used with a single error microphone located in the radiated acoustic field. Global attenuation of radiated sound was observed to occur by two main mechanisms. For 'on-resonance' excitation, the control force had the effect of increasing the total panel input impedance presented to the nosie source, thus reducing all radiated sound. For 'off-resonance' excitation, the control force tends not significantly to modify the panel total response amplitude but rather to restructure the relative phases of the modes leading to a more complex vibration pattern and a decrease in radiation efficiency. For acoustic control, the second method, the number of acoustic sources required for global reduction was seen to increase with panel modal order. The mechanism in this case was that the acoustic sources tended to create an inverse pressure distribution at the panel surface and thus 'unload' the panel by reducing the panel radiation impedance. In general, control by structural inputs appears more effective than control by acoustic sources for structurally radiated noise.

  19. Voltage and Current Unbalance Compensation Using a Parallel Active Filter

    SciTech Connect

    Xu, Yan; Tolbert, Leon M; Kueck, John D; Rizy, D Tom

    2007-01-01

    A three-phase insulated gate bipolar transistor (IGBT)-based parallel active filter is used for current and/or voltage unbalance compensation. An instantaneous power theory is adopted for real-time calculation and control. Three control schemes, current control, voltage control, and integrated control are proposed to compensate the unbalance of current, voltage, or both. The compensation results of the different control schemes in unbalance cases (load unbalance or voltage source unbalance) are compared and analyzed. The simulation and experimental results show that the control schemes can compensate the unbalance in load current or in the voltage source. Different compensation objectives can be achieved, i.e., balanced and unity power factor source current, balanced and regulated voltage, or both, by choosing appropriate control schemes.

  20. Distinct Spatiotemporal Activation Patterns of the Perirhinal-Entorhinal Network in Response to Cortical and Amygdala Input

    PubMed Central

    Willems, Janske G. P.; Wadman, Wytse J.; Cappaert, Natalie L. M.

    2016-01-01

    The perirhinal (PER) and entorhinal cortex (EC) receive input from the agranular insular cortex (AiP) and the subcortical lateral amygdala (LA) and the main output area is the hippocampus. Information transfer through the PER/EC network however, is not always guaranteed. It is hypothesized that this network actively regulates the (sub)cortical activity transfer to the hippocampal network and that the inhibitory system is involved in this function. This study determined the recruitment by the AiP and LA afferents in PER/EC network with the use of voltage sensitive dye (VSD) imaging in horizontal mouse brain slices. Electrical stimulation (500 μA) of the AiP induced activity that gradually propagated predominantly in the rostro-caudal direction: from the PER to the lateral EC (LEC). In the presence of 1 μM of the competitive γ-aminobutyric acid (GABAA) receptor antagonist bicuculline, AiP stimulation recruited the medial EC (MEC) as well. In contrast, LA stimulation (500 μA) only induced activity in the deep layers of the PER. In the presence of bicuculline, the initial population activity in the PER propagated further towards the superficial layers and the EC after a delay. The latency of evoked responses decreased with increasing stimulus intensities (50–500 μA) for both the AiP and LA stimuli. The stimulation threshold for evoking responses in the PER/EC network was higher for the LA than for the AiP. This study showed that the extent of the PER/EC network activation depends on release of inhibition. When GABAA dependent inhibition is reduced, both the AiP and the LA activate spatially overlapping regions, although in a distinct spatiotemporal fashion. It is therefore hypothesized that the inhibitory network regulates excitatory activity from both cortical and subcortical areas that has to be transmitted through the PER/EC network. PMID:27378860

  1. Current Activity of the U.S. ASTER Science Team

    NASA Technical Reports Server (NTRS)

    Kahle, A. B.; Abrams, M. J.; Hook, S. J.; Pieri, D. C.; Ramsey, M.; Rowan, L. C.; Schmugge, T.; Wessels, R.

    2001-01-01

    The U.S. ASTER Science Team is currently engaged in numerous ASTER related activities, many of them jointly with our Japanese colleagues. These include vicarious instrument calibration, algorithm development and validation for higher level data products, assistance to ERSDAC for scheduling activities (primarily for U.S. users), assistance to data users other than Science Team members, and science applications of ASTER data, notably in the areas of glacial monitoring, volcanic monitoring, heat balance determinations, geologic mapping, and cloud studies.

  2. IS THE CURRENT LACK OF SOLAR ACTIVITY ONLY SKIN DEEP?

    SciTech Connect

    Broomhall, A.-M.; Chaplin, W. J.; Elsworth, Y.; Fletcher, S. T.; New, R. E-mail: wjc@bison.ph.bham.ac.uk E-mail: S.Fletcher@shu.ac.uk

    2009-08-01

    The Sun is a variable star whose magnetic activity and total irradiance vary on a timescale of approximately 11 years. The current activity minimum has attracted considerable interest because of its unusual duration and depth. This raises the question: what might be happening beneath the surface where the magnetic activity ultimately originates? The surface activity can be linked to the conditions in the solar interior by the observation and analysis of the frequencies of the Sun's natural seismic modes of oscillation-the p modes. These seismic frequencies respond to changes in activity and are probes of conditions within the Sun. The Birmingham Solar-Oscillations Network (BiSON) has made measurements of p-mode frequencies over the last three solar activity cycles, and so is in a unique position to explore the current unusual and extended solar minimum. We show that the BiSON data reveal significant variations of the p-mode frequencies during the current minimum. This is in marked contrast to the surface activity observations, which show little variation over the same period. The level of the minimum is significantly deeper in the p-mode frequencies than in the surface observations. We observe a quasi-biennial signal in the p-mode frequencies, which has not previously been observed at mid- and low-activity levels. The stark differences in the behavior of the frequencies and the surface activity measures point to activity-related processes occurring in the solar interior, which are yet to reach the surface, where they may be attenuated.

  3. Inhibitory Input from the Lateral Hypothalamus to the Ventral Tegmental Area Disinhibits Dopamine Neurons and Promotes Behavioral Activation.

    PubMed

    Nieh, Edward H; Vander Weele, Caitlin M; Matthews, Gillian A; Presbrey, Kara N; Wichmann, Romy; Leppla, Christopher A; Izadmehr, Ehsan M; Tye, Kay M

    2016-06-15

    Projections from the lateral hypothalamus (LH) to the ventral tegmental area (VTA), containing both GABAergic and glutamatergic components, encode conditioned responses and control compulsive reward-seeking behavior. GABAergic neurons in the LH have been shown to mediate appetitive and feeding-related behaviors. Here we show that the GABAergic component of the LH-VTA pathway supports positive reinforcement and place preference, while the glutamatergic component mediates place avoidance. In addition, our results indicate that photoactivation of these projections modulates other behaviors, such as social interaction and perseverant investigation of a novel object. We provide evidence that photostimulation of the GABAergic LH-VTA component, but not the glutamatergic component, increases dopamine (DA) release in the nucleus accumbens (NAc) via inhibition of local VTA GABAergic neurons. Our study clarifies how GABAergic LH inputs to the VTA can contribute to generalized behavioral activation across multiple contexts, consistent with a role in increasing motivational salience. VIDEO ABSTRACT. PMID:27238864

  4. Calcium-activated non-selective cation currents are involved in generation of tonic and bursting activity in dopamine neurons of the substantia nigra pars compacta.

    PubMed

    Mrejeru, Ana; Wei, Aguan; Ramirez, Jan Marino

    2011-05-15

    Nigral dopamine neurons are transiently activated by high frequency glutamatergic inputs relaying reward-predicting sensory information. The tonic firing pattern of dopamine cells responds to these inputs with a transient burst of spikes that requires NMDA receptors. Here, we show that NMDA receptor activation further excites the cell by recruiting a calcium-activated non-selective cation current (ICAN) capable of generating a plateau potential. Burst firing in vitro is eliminated after blockade of ICAN with flufenamic acid, 9-phenanthrol, or intracellular BAPTA. ICAN is likely to be mediated by a transient receptor potential (TRP) channel, and RT-PCR was used to confirm expression of TRPM2 and TRPM4mRNA in substantia nigra pars compacta.We propose that ICAN is selectively activated during burst firing to boost NMDA currents and allow plateau potentials. This boost mechanism may render DA cells vulnerable to excitotoxicity. PMID:21486760

  5. The Current State of Marketing Activity among Higher Education Institutions.

    ERIC Educational Resources Information Center

    Newman, Cynthia M.

    2002-01-01

    Investigated the current state of marketing, marketing research, and planning practices at four-year higher education institutions. Builds upon previous studies by Blackburn (1979) and Goldgehn (1982 and 1989). Determined whether the use and apparent understanding of marketing and its attendant activities by admissions and enrollment management…

  6. Optogenetic activation of nigral inhibitory inputs to motor thalamus in the mouse reveals classic inhibition with little potential for rebound activation.

    PubMed

    Edgerton, Jeremy R; Jaeger, Dieter

    2014-01-01

    The inhibitory output from the internal pallidum and substantia nigra to the thalamus forms an important link in the transmission of basal ganglia processing to cortex. Two hypotheses consider either inhibition of thalamic activity or thalamic excitation via post-inhibitory rebound burst firing as the functional mode of this link. We used optogenetics to characterize the synaptic properties of nigral input to motor thalamus in adult mouse brain slices, and to determine in what conditions the nigral inhibition of motor thalamus is transmitted via inhibition or rebound firing. Our results are more consistent with graded inhibition of spiking for conditions expected in normal awake animals, because inhibitory potentials from nigral input were generally not sufficient to elicit rebound spikes when the thalamic neurons were actively firing. However, with bursty or fast trains of nigral input low-threshold rebound spike bursts could be triggered for low levels of excitation. This may form the basis of pathological burst generation and transmission in parkinsonian conditions. PMID:24574972

  7. Changes in muscle activation patterns in response to enhanced sensory input during treadmill stepping in infants born with myelomeningocele

    PubMed Central

    Pantall, Annette; Teulier, Caroline; Ulrich, Beverly D.

    2013-01-01

    Infants with myelomeningocele (MMC) increase step frequency in response to modifications to the treadmill surface. The aim was to investigate how these modifications impacted the electromyographic (EMG) patterns. We analyzed EMG from 19 infants aged 2–10 months, with MMC at the lumbosacral level. We supported infants upright on the treadmill for 12 trials, each 30 seconds long. Modifications included visual flow, unloading, weights, Velcro and lcriction. Surface electrodes recorded EMG from tibialis anterior, lateral gastrocnemius, rectus femoris and biceps femoris. We determined muscle bursts for each stride cycle and from these calculated various parameters. Results indicated that each of the five sensory conditions generated different motor patterns. Visual flow and friction which we previously reported increased step frequency impacted lateral gastrocnemius most. Weights, which significantly decreased step frequency increased burst duration and co-activity of the proximal muscles. We also observed an age effect, with all conditions increasing muscle activity in younger infants whereas in older infants visual flow and unloading stimulated most activity. In conclusion, we have demonstrated that infants with myelomeningocele at levels which impact the myotomes of major locomotor muscles find ways to respond and adapt their motor output to changes in sensory input. PMID:23158017

  8. Activation of Ca2+-activated Cl- current by depolarizing steps in rabbit urethral interstitial cells.

    PubMed

    Hollywood, M A; Sergeant, G P; McHale, N G; Thornbury, K D

    2003-08-01

    Interstitial cells were isolated from strips of rabbit urethra for study using the amphotericin B perforated-patch technique. Depolarizing steps to -30 mV or greater activated a Ca2+ current (ICa), followed by a Ca2+-activated Cl- current, and, on stepping back to -80 mV, large Cl- tail currents were observed. Both currents were abolished when the cells were superfused with Ca2+-free bath solution, suggesting that Ca2+ influx was necessary for activation of the Cl- current. The Cl- current was also abolished when Ba2+ was substituted for Ca2+ in the bath or the cell was dialyzed with EGTA (2 mM). The Cl- current was also reduced by cyclopiazonic acid, ryanodine, 2-aminoethoxydiphenyl borate (2-APB), and xestospongin C, suggesting that Ca2+-induced Ca2+ release (CICR) involving both ryanodine and inositol 1,4,5-trisphosphate receptors contributes to its activation. PMID:12672653

  9. Ca2+-activated Cl− current in rabbit sinoatrial node cells

    PubMed Central

    Verkerk, Arie O; Wilders, Ronald; Zegers, Jan G; van Borren, Marcel M G J; Ravesloot, Jan H; Verheijck, E Etienne

    2002-01-01

    The Ca2+-activated Cl− current (ICl(Ca)) has been identified in atrial, Purkinje and ventricular cells, where it plays a substantial role in phase-1 repolarization and delayed after-depolarizations. In sinoatrial (SA) node cells, however, the presence and functional role of ICl(Ca) is unknown. In the present study we address this issue using perforated patch-clamp methodology and computer simulations. Single SA node cells were enzymatically isolated from rabbit hearts. ICl(Ca) was measured, using the perforated patch-clamp technique, as the current sensitive to the anion blocker 4,4′-diisothiocyanostilbene-2,2′-disulphonic acid (DIDS). Voltage clamp experiments demonstrate the presence of ICl(Ca) in one third of the spontaneously active SA node cells. The current was transient outward with a bell-shaped current-voltage relationship. Adrenoceptor stimulation with 1 μm noradrenaline doubled the ICl(Ca) density. Action potential clamp measurements demonstrate that ICl(Ca) is activate late during the action potential upstroke. Current clamp experiments show, both in the absence and presence of 1 μm noradrenaline, that blockade of ICl(Ca) increases the action potential overshoot and duration, measured at 20 % repolarization. However, intrinsic interbeat interval, upstroke velocity, diastolic depolarization rate and the action potential duration measured at 50 and 90 % repolarization were not affected. Our experimental data are supported by computer simulations, which additionally demonstrate that ICl(Ca) has a limited role in pacemaker synchronization or action potential conduction. In conclusion, ICl(Ca) is present in one third of SA node cells and is activated during the pacemaker cycle. However, ICl(Ca) does not modulate intrinsic interbeat interval, pacemaker synchronization or action potential conduction. PMID:11927673

  10. Modulation of motor activity by cutaneous input: inhibition of the magnetic motor evoked potential by digital electrical stimulation.

    PubMed

    Clouston, P D; Kiers, L; Menkes, D; Sander, H; Chiappa, K; Cros, D

    1995-04-01

    We examined the inhibitory effect of a brief train of digital (D2) electrical stimuli at 4 times perception threshold on transcranial magnetic motor evoked potentials (MEPs) recorded from abductor pollicis brevis (APB) and flexor carpi radialis (FCR) muscles ipsilateral to the side of D2 stimulation. We compared this to the inhibitory effect of ipsilateral D2 stimulation on averaged rectified EMG recorded at 10% maximum voluntary contraction and on F-responses and H-reflexes recorded from these same muscles. We also compared MEPs recorded following D2 stimulation just above perception threshold to MEPs following higher intensity D2 stimulation. As well, we assessed the effect of preceding D2 stimulation on MEPs recorded from a relaxed versus tonically contracted hand muscle. D2 stimulation elicited a triphasic response of modest MEP facilitation followed by inhibition and further facilitation. The duration and onset of MEP inhibition correlated with those of the initial period of rectified EMG inhibition, however, the magnitude of MEP inhibition was generally less than the magnitude of EMG inhibition, consistent with a greater inhibitory effect of digital afferents on smaller motor neurons. MEPs were not facilitated during the rebound of EMG activity (the E2 period) that usually followed the initial period of EMG inhibition (I1 period). The behavior of H-reflexes and F-responses following ipsilateral D2 stimulation suggested that inhibition of both EMG and MEPs is not mediated via presynaptic inhibition of Ia afferents, and that inhibition is augmented by descending rather than segmental input to spinal motor neurons. Tonic contraction of the target muscle during D2 stimulation decreased the inhibitory effect of the preceding digital stimulus possibly due to recruitment of larger spinal motor neurons less likely to be inhibited by cutaneous input. PMID:7537203

  11. Calcium release-activated calcium current in rat mast cells.

    PubMed

    Hoth, M; Penner, R

    1993-06-01

    1. Whole-cell patch clamp recordings of membrane currents and fura-2 measurements of free intracellular calcium concentration ([Ca2+]i) were used to study the biophysical properties of a calcium current activated by depletion of intracellular calcium stores in rat peritoneal mast cells. 2. Calcium influx through an inward calcium release-activated calcium current (ICRAC) was induced by three independent mechanisms that result in store depletion: intracellular infusion of inositol 1,4,5-trisphosphate (InsP3) or extracellular application of ionomycin (active depletion), and intracellular infusion of calcium chelators (ethylene glycol bis-N,N,N',N'-tetraacetic acid (EGTA) or 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA)) to prevent reuptake of leaked-out calcium into the stores (passive depletion). 3. The activation of ICRAC induced by active store depletion has a short delay (4-14 s) following intracellular infusion of InsP3 or extracellular application of ionomycin. It has a monoexponential time course with a time constant of 20-30 s and, depending on the complementary Ca2+ buffer, a mean normalized amplitude (at 0 mV) of 0.6 pA pF-1 (with EGTA) and 1.1 pA pF-1 (with BAPTA). 4. After full activation of ICRAC by InsP3 in the presence of EGTA (10 mM), hyperpolarizing pulses to -100 mV induced an instantaneous inward current that decayed by 64% within 50 ms. This inactivation is probably mediated by [Ca2+]i, since the decrease of inward current in the presence of the fast Ca2+ buffer BAPTA (10 mM) was only 30%. 5. The amplitude of ICRAC was dependent on the extracellular Ca2+ concentration with an apparent dissociation constant (KD) of 3.3 mM. Inward currents were nonsaturating up to -200 mV. 6. The selectivity of ICRAC for Ca2+ was assessed by using fura-2 as the dominant intracellular buffer (at a concentration of 2 mM) and relating the absolute changes in the calcium-sensitive fluorescence (390 nm excitation) with the calcium current integral

  12. Pharmacological characterization of BDNF promoters I, II and IV reveals that serotonin and norepinephrine input is sufficient for transcription activation.

    PubMed

    Musazzi, L; Rimland, J M; Ieraci, A; Racagni, G; Domenici, E; Popoli, M

    2014-05-01

    Compelling evidence has shown that the effects of antidepressants, increasing extracellular serotonin and noradrenaline as a primary mechanism of action, involve neuroplastic and neurotrophic mechanisms. Brain-derived neurotrophic factor (BDNF) has been shown to play a key role in neuroplasticity and synaptic function, as well as in the pathophysiology of neuropsychiatric disorders and the mechanism of action of antidepressants. The expression of BDNF is mediated by the transcription of different mRNAs derived by the splicing of one of the eight 5' non-coding exons with the 3' coding exon (in rats). The transcription of each non-coding exon is driven by unique and different promoters. We generated a gene reporter system based on hippocampal and cortical neuronal cultures, in which the transcription of luciferase is regulated by BDNF promoters I, II, IV or by cAMP response element (CRE), to investigate the activation of selected promoters induced by monoaminergic antidepressants and by serotonin or noradrenaline agonists. We found that incubation with fluoxetine or reboxetine failed to induce any activation of BDNF promoters or CRE. On the other hand, the incubation of cultures with selective agonists of serotonin or noradrenaline receptors induced a specific and distinct profile of activation of BDNF promoters I, II, IV and CRE, suggesting that the monoaminergic input, absent in dissociated cultures, is essential for the modulation of BDNF expression. In summary, we applied a rapidly detectable and highly sensitive reporter gene assay to characterize the selective activation profile of BDNF and CRE promoters, through specific and different pharmacological stimuli. PMID:24451568

  13. Both olfactory epithelial and vomeronasal inputs are essential for activation of the medial amygdala and preoptic neurons of male rats.

    PubMed

    Dhungel, S; Masaoka, M; Rai, D; Kondo, Y; Sakuma, Y

    2011-12-29

    Chemosensory inputs signaling volatile and nonvolatile molecules play a pivotal role in sexual and social behavior in rodents. We have demonstrated that olfactory preference in male rats, that is, attraction to receptive female odors, is regulated by the medial amygdala (MeA), the cortical amygdala (CoA), and the preoptic area (POA). In this paper, we investigated the involvement of two chemosensory organs, the olfactory epithelium (OE) and the vomeronasal organ (VNO), in olfactory preference and copulatory behavior in male rats. We found that olfactory preferences were impaired by zinc sulfate lesion of the OE but not surgical removal of the VNO. Copulatory behaviors, especially intromission frequency and ejaculation, were also suppressed by zinc sulfate treatment. Neuronal activation in the accessory olfactory bulb (AOB), the MeA, the CoA, and the POA was analyzed after stimulation by airborne odors or soiled bedding of estrous females using cFos immunohistochemistry. Although the OE and VNO belong to different neural systems, the main and accessory olfactory systems, respectively, both OE lesion and VNO removal almost equally suppressed the number of cFos-immunoreactive cells in those areas that regulate olfactory preference. These results suggest that signals received by the OE and VNO interact and converge in the early stage of olfactory processing, in the AOB and its targets, although they have distinct roles in the regulation of social behaviors. PMID:21983295

  14. Improved Active Harmonic Current Elimination Based on Voltage Detection.

    PubMed

    Tan, Tianyuan; Dong, Shuan; Huang, Yingwei; Liu, Jian; Le, Jian; Liu, Kaipei

    2016-01-01

    With the increasing penetration of power electronic equipment in modern residential distribution systems, harmonics mitigation through the distributed generation (DG) interfacing converters has received significant attention. Among recently proposed methods, the so-called active resonance damper (ARD) and harmonic voltage compensator (HVC) based on voltage detection can effectively reduce the harmonic distortions in selected areas of distribution systems. However, it is found out that when traditional ARD algorithm is used to eliminate harmonic current injected by non-linear loads, its performance is constrained by stability problems and can at most eliminate half of the load harmonic currents. Thus, inspired by the duality between ARD and HVC, this paper presents a novel improved resistive active power filter (R-APF) algorithm based on integral-decoupling control. The design guideline for its parameters is then investigated through carefully analyzing the closed-loop poles' trajectory. Computer studies demonstrate that the proposed algorithm can effectively mitigate the load harmonic currents and its performance is much better than traditional ARD based on proportional control. PMID:27295213

  15. Improved Active Harmonic Current Elimination Based on Voltage Detection

    PubMed Central

    Tan, Tianyuan; Dong, Shuan; Huang, Yingwei; Liu, Jian; Le, Jian; Liu, Kaipei

    2016-01-01

    With the increasing penetration of power electronic equipment in modern residential distribution systems, harmonics mitigation through the distributed generation (DG) interfacing converters has received significant attention. Among recently proposed methods, the so-called active resonance damper (ARD) and harmonic voltage compensator (HVC) based on voltage detection can effectively reduce the harmonic distortions in selected areas of distribution systems. However, it is found out that when traditional ARD algorithm is used to eliminate harmonic current injected by non-linear loads, its performance is constrained by stability problems and can at most eliminate half of the load harmonic currents. Thus, inspired by the duality between ARD and HVC, this paper presents a novel improved resistive active power filter (R-APF) algorithm based on integral-decoupling control. The design guideline for its parameters is then investigated through carefully analyzing the closed-loop poles’ trajectory. Computer studies demonstrate that the proposed algorithm can effectively mitigate the load harmonic currents and its performance is much better than traditional ARD based on proportional control. PMID:27295213

  16. Repeating Spatial-Temporal Motifs of CA3 Activity Dependent on Engineered Inputs from Dentate Gyrus Neurons in Live Hippocampal Networks

    PubMed Central

    Bhattacharya, Aparajita; Desai, Harsh; DeMarse, Thomas B.; Wheeler, Bruce C.; Brewer, Gregory J.

    2016-01-01

    Anatomical and behavioral studies, and in vivo and slice electrophysiology of the hippocampus suggest specific functions of the dentate gyrus (DG) and the CA3 subregions, but the underlying activity dynamics and repeatability of information processing remains poorly understood. To approach this problem, we engineered separate living networks of the DG and CA3 neurons that develop connections through 51 tunnels for axonal communication. Growing these networks on top of an electrode array enabled us to determine whether the subregion dynamics were separable and repeatable. We found spontaneous development of polarized propagation of 80% of the activity in the native direction from DG to CA3 and different spike and burst dynamics for these subregions. Spatial-temporal differences emerged when the relationships of target CA3 activity were categorized with to the number and timing of inputs from the apposing network. Compared to times of CA3 activity when there was no recorded tunnel input, DG input led to CA3 activity bursts that were 7× more frequent, increased in amplitude and extended in temporal envelope. Logistic regression indicated that a high number of tunnel inputs predict CA3 activity with 90% sensitivity and 70% specificity. Compared to no tunnel input, patterns of >80% tunnel inputs from DG specified different patterns of first-to-fire neurons in the CA3 target well. Clustering dendrograms revealed repeating motifs of three or more patterns at up to 17 sites in CA3 that were importantly associated with specific spatial-temporal patterns of tunnel activity. The number of these motifs recorded in 3 min was significantly higher than shuffled spike activity and not seen above chance in control networks in which CA3 was apposed to CA3 or DG to DG. Together, these results demonstrate spontaneous input-dependent repeatable coding of distributed activity in CA3 networks driven by engineered inputs from DG networks. These functional configurations at measured times

  17. Flowpath acceleration vs flowpath activation: how do hydrologic systems respond to dynamic inputs and changes in storage?

    NASA Astrophysics Data System (ADS)

    Harman, Ciaran

    2016-04-01

    The response of catchments to rainfall or snowmelt can be understood in terms of the propagation and dissipation of a wave of fluid energy, and in terms of the translation of fluid parcels in space. The first determines the amount of flow in a stream, and the second determines the age composition of that streamflow. However, these are not distinct phenomena, but two aspects of the integrated catchment scale hydrologic response. Previous work has shown that catchment storage is the dominant state variable controlling both the magnitude of the flow response and the age composition of that flow response. Here, I will present a succinct framework that unifies the flow and transport properties of a watershed, and their relationship to storage. This framework further extends rank StorAge Selection (rSAS) function theory. The framework suggests that the hydrologic response of a watershed to inputs can be understood to consist of two modalities: flowpath acceleration and flowpath activation. In the first case, additional potential energy drives an acceleration of flowpaths, so that water of all ages moves more quickly toward the catchment outlet. In the second case, the additional new water moves toward the outlet along newly-activated flow paths without modifying the velocity of water previously in the watershed. Real hydrologic systems may exhibit some combination of both modalities across their age-ranked storage. The proposed framework allows the dominant modalities of a given hydrologic system to be explored with few a priori assumptions. Data from several hydrologic systems will be used to demonstrate the method, and gain insights into the sensitivity of catchment flow and transport in variable climatic conditions.

  18. Voltage Dependence of a Neuromodulator-Activated Ionic Current123

    PubMed Central

    2016-01-01

    Abstract The neuromodulatory inward current (IMI) generated by crab Cancer borealis stomatogastric ganglion neurons is an inward current whose voltage dependence has been shown to be crucial in the activation of oscillatory activity of the pyloric network of this system. It has been previously shown that IMI loses its voltage dependence in conditions of low extracellular calcium, but that this effect appears to be regulated by intracellular calmodulin. Voltage dependence is only rarely regulated by intracellular signaling mechanisms. Here we address the hypothesis that the voltage dependence of IMI is mediated by intracellular signaling pathways activated by extracellular calcium. We demonstrate that calmodulin inhibitors and a ryanodine antagonist can reduce IMI voltage dependence in normal Ca2+, but that, in conditions of low Ca2+, calmodulin activators do not restore IMI voltage dependence. Further, we show evidence that CaMKII alters IMI voltage dependence. These results suggest that calmodulin is necessary but not sufficient for IMI voltage dependence. We therefore hypothesize that the Ca2+/calmodulin requirement for IMI voltage dependence is due to an active sensing of extracellular calcium by a GPCR family calcium-sensing receptor (CaSR) and that the reduction in IMI voltage dependence by a calmodulin inhibitor is due to CaSR endocytosis. Supporting this, preincubation with an endocytosis inhibitor prevented W7 (N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride)-induced loss of IMI voltage dependence, and a CaSR antagonist reduced IMI voltage dependence. Additionally, myosin light chain kinase, which is known to act downstream of the CaSR, seems to play a role in regulating IMI voltage dependence. Finally, a Gβγ-subunit inhibitor also affects IMI voltage dependence, in support of the hypothesis that this process is regulated by a G-protein-coupled CaSR. PMID:27257619

  19. Current water resources activities in Alabama, fiscal year 1986

    USGS Publications Warehouse

    Slack, L.J.; Meadows, E.A.

    1986-01-01

    The purpose of this report is to describe the current (as of 1986) water resources activities of the U.S. Geological Survey in Alabama. The responsibilities and objectives of the Survey; organization of the Alabama District; sources of funding; current projects; hydrologic data program; and a selected bibliography of hydrologic reports are presented. Water resources projects are undertaken usually at the request of and with partial funding from another agency, provided: they are high priority problems and generally identified to fall within the mission of the Water Resources Division and they are consistent with the Program Management Plan developed by the Water Resources Division in Alabama to meet the long range plan for hydrologic data in the State. (USGS)

  20. Data Mining Activities for Bone Discipline - Current Status

    NASA Technical Reports Server (NTRS)

    Sibonga, J. D.; Pietrzyk, R. A.; Johnston, S. L.; Arnaud, S. B.

    2008-01-01

    The disciplinary goals of the Human Research Program are broadly discussed. There is a critical need to identify gaps in the evidence that would substantiate a skeletal health risk during and after spaceflight missions. As a result, data mining activities will be engaged to gather reviews of medical data and flight analog data and to propose additional measures and specific analyses. Several studies are briefly reviewed which have topics that partially address these gaps in knowledge, including bone strength recovery with recovery of bone mass density, current renal stone formation knowledge, herniated discs, and a review of bed rest studies conducted at Ames Human Research Facility.

  1. Monitoring the excitability of neocortical efferent neurons to direct activation by extracellular current pulses.

    PubMed

    Swadlow, H A

    1992-08-01

    1. Extracellular action potentials were recorded from antidromically activated efferent neurons in visual, somatosensory, and motor cortex of the awake rabbit using low-impedance metal microelectrodes. Efferent neurons were also activated by current pulses delivered near the soma [juxtasomal current pulses (JSCPs)] through the recording microelectrode. Action potentials generated by JSCPs were not directly observed (because of the stimulus artifact), but were inferred with the use of a collision paradigm. Efferent populations studied include callosal neurons [CC (n = 80)], ipsilateral corticocortical neurons [C-IC (n = 21)], corticothalamic neurons of layer 6 [CF-6 (n = 57)], and descending corticofugal neurons of layer 5 [CF-5, corticotectal neurons of the visual cortex (n = 48)]. 2. Most CC neurons (45/46) and all C-IC (8/8) and CF-6 neurons (39/39) were directly activated by JSCPs at near-threshold intensities. Some CF-5 neurons (9/38), however, showed evidence of indirect activation. All efferent classes had similar current thresholds (means 1.85-2.10 microA) to direct activation by JSCPs, and thresholds were inversely related to extracellular spike amplitude. For each neuron, the range of JSCP intensities that generated response probabilities of between 0.2 and 0.8 was measured, and this "range of uncertainty" was significantly greater in CF-5 neurons (mean 32.7% of threshold) than in CC (mean 19.0%) or CF-6 (mean 20.4%) neurons. 3. Several factors indicate that the threshold of efferent neurons to JSCPs is very sensitive to excitatory and inhibitory synaptic inputs. Iontophoretic applications of gamma-aminobutyric acid (GABA) increased the threshold to JSCPs, and glutamate reduced the threshold. Electrical stimulation of afferent pathways at intensities just below threshold for eliciting action potentials resulted in a dramatic decrease in JSCP threshold. This initial short-latency threshold decrease was specific to stimulation of particular afferent pathways

  2. Current status of health promotion activities in four midwest cities.

    PubMed

    Weisbrod, R R; Bracht, N F; Pirie, P L; Veblen-Mortenson, S

    1991-01-01

    Community-wide surveys were conducted in Winona and St. Cloud, MN, Eau Claire, WI, and Sioux Falls, SD, in 1986 and 1987 to determine the current status of the supply and demand of health promotion activities in nine categories. Supply and demand indicators were conceptualized and defined as program options (different activities in a coded list) and participation (registrations). An annual inventory of all health promotion activities in each community was complied from interviews with providers of such activities. Interviews of probable community providers was followed by a nomination process to identify others. Providers at worksites were interviewed in a separate study with matching data endpoints. Results show that exercise programs have the highest levels of options and participation in all four cities. On the supply side of total programs offered, there was similarity in rates among three of the cities, with only Winona offering more health promotion opportunities. There was similarity also in the areas of health where most programs are offered, favoring exercise, followed by the heart disease risk factor areas of screening, smoking cessation, and nutrition education. On the demand side of participation, there was similarity in total participation rates among three of the four cities with Sioux Falls showing substantially higher demand. Exercise showed the highest participation in all cities, but there was little similarity among the cities in ranking participation in the other areas of health promotion. In the four cities combined, high levels of program options with low participation were characteristic of smoking cessation. In contrast, low levels of program options and high participation were shown in chemical dependency. Worksites are the main providers of health promotion programs for adults, with schools and colleges also major program providers. Educational organizations account for the largest percentage of total participation in health promotion

  3. Current activities handbook: formerly utilized sites remedial action program

    SciTech Connect

    1981-02-27

    This volume is one of a series produced under contract with the DOE, by Politech Corporation to develop a legislative and regulatory data base to assist the FUSRAP management in addressing the institutional and socioeconomic issues involved in carrying out the Formerly Utilized Sites Remedial Action Program. This Information Handbook series contains information about all relevant government agencies at the Federal and state levels, the pertinent programs they administer, each affected state legislature, and current Federal and state legislative and regulatory initiatives. This volume is a compilation of information about the activities each of the thirteen state legislatures potentially affected by the Formerly Utilized Sites Remedial Action Program. It contains a description of the state legislative procedural rules and a schedule of each legislative session; a summary of pending relevant legislation; the name and telephone number of legislative and state agency contacts; and the full text of all bills identified.

  4. IHY Activities in Africa: Current Status and Future Developments

    NASA Astrophysics Data System (ADS)

    Rabiu, A. B.; Balogun, E. E.

    2006-11-01

    The International Heliophysical Year (IHY) has already gained a global acceptance as international research cooperation. This paper assesses the current status of IHY; its organization, activities and challenges in Nigeria and THE African continent as a whole. The tremendous impact and successes of the program is highlighted. Two successful annual workshops have been held at different locations with wide national representation. A few facilities already installed or secured are presented for probable exploration and forging of partnership in research. On-going research involvement with SCINDA, AWESOME and MAGDAS are presented. With the passing of the dip equator through the country, Nigeria is presented as a region for ground observation and measurements of geo- and helio-physical variables. Ways by which Nigerian scientists are taking advantage of the opportunities embedded in the international program are exposed. Benefits of IHY including training, collaboration, workshop participation and publications, are explored.

  5. Current Reactor Physics Benchmark Activities at the Idaho National Laboratory

    SciTech Connect

    John D. Bess; Margaret A. Marshall; Mackenzie L. Gorham; Joseph Christensen; James C. Turnbull; Kim Clark

    2011-11-01

    The International Reactor Physics Experiment Evaluation Project (IRPhEP) [1] and the International Criticality Safety Benchmark Evaluation Project (ICSBEP) [2] were established to preserve integral reactor physics and criticality experiment data for present and future research. These valuable assets provide the basis for recording, developing, and validating our integral nuclear data, and experimental and computational methods. These projects are managed through the Idaho National Laboratory (INL) and the Organisation for Economic Co-operation and Development Nuclear Energy Agency (OECD-NEA). Staff and students at the Department of Energy - Idaho (DOE-ID) and INL are engaged in the development of benchmarks to support ongoing research activities. These benchmarks include reactors or assemblies that support Next Generation Nuclear Plant (NGNP) research, space nuclear Fission Surface Power System (FSPS) design validation, and currently operational facilities in Southeastern Idaho.

  6. Radio Astronomy in Malaysia: Current Status and Outreach Activities

    NASA Astrophysics Data System (ADS)

    Hashim, N.; Abidin, Z. Z.; Ibrahim, U. F. S. U.; Umar, R.; Hassan, M. S. R.; Rosli, Z.; Hamidi, Z. S.; Ibrahim, Z. A.

    2011-12-01

    In this paper, we will present the current status of radio astronomical research and outreach in Malaysia. We will also present a short history of our research group, which is currently the only radio astronomical facility in Malaysia. Our group is called the Radio Cosmology Research Lab and was established in 2005 by Dr Zamri Zainal Abidin and Prof Dr Zainol Abidin Ibrahim. We will discuss the future plans for this group including our keen interest in being part of a more global network of radio astronomers. We are already an active member of the South-East Asia Astronomy Network (SEAAN) and aims to have a radio astronomical facility in order to join the Global Very Long Baseline Interferometer (VLBI) as well becoming a research hub for the future Square Kilometer Array (SKA) project. We will also present some of the scientific goals of our group including providing a platform for radio astronomers to be able to do observations of weak and high red-shifted radio objects such as galaxy clusters and supernovae.

  7. Systems and methods for reconfiguring input devices

    NASA Technical Reports Server (NTRS)

    Lancaster, Jeff (Inventor); De Mers, Robert E. (Inventor)

    2012-01-01

    A system includes an input device having first and second input members configured to be activated by a user. The input device is configured to generate activation signals associated with activation of the first and second input members, and each of the first and second input members are associated with an input function. A processor is coupled to the input device and configured to receive the activation signals. A memory coupled to the processor, and includes a reconfiguration module configured to store the input functions assigned to the first and second input members and, upon execution of the processor, to reconfigure the input functions assigned to the input members when the first input member is inoperable.

  8. Measuring Input Thresholds on an Existing Board

    NASA Technical Reports Server (NTRS)

    Kuperman, Igor; Gutrich, Daniel G.; Berkun, Andrew C.

    2011-01-01

    A critical PECL (positive emitter-coupled logic) interface to Xilinx interface needed to be changed on an existing flight board. The new Xilinx input interface used a CMOS (complementary metal-oxide semiconductor) type of input, and the driver could meet its thresholds typically, but not in worst-case, according to the data sheet. The previous interface had been based on comparison with an external reference, but the CMOS input is based on comparison with an internal divider from the power supply. A way to measure what the exact input threshold was for this device for 64 inputs on a flight board was needed. The measurement technique allowed an accurate measurement of the voltage required to switch a Xilinx input from high to low for each of the 64 lines, while only probing two of them. Directly driving an external voltage was considered too risky, and tests done on any other unit could not be used to qualify the flight board. The two lines directly probed gave an absolute voltage threshold calibration, while data collected on the remaining 62 lines without probing gave relative measurements that could be used to identify any outliers. The PECL interface was forced to a long-period square wave by driving a saturated square wave into the ADC (analog to digital converter). The active pull-down circuit was turned off, causing each line to rise rapidly and fall slowly according to the input s weak pull-down circuitry. The fall time shows up as a change in the pulse width of the signal ready by the Xilinx. This change in pulse width is a function of capacitance, pulldown current, and input threshold. Capacitance was known from the different trace lengths, plus a gate input capacitance, which is the same for all inputs. The pull-down current is the same for all inputs including the two that are probed directly. The data was combined, and the Excel solver tool was used to find input thresholds for the 62 lines. This was repeated over different supply voltages and

  9. Proton activity of the Sun in current solar cycle 24

    NASA Astrophysics Data System (ADS)

    Li, Chuan; Miroshnichenko, Leonty I.; Fang, Cheng

    2015-07-01

    We present a study of seven large solar proton events in the current solar cycle 24 (from 2009 January up to the current date). They were recorded by the GOES spacecraft with the highest proton fluxes being over 200 pfu for energies >10 MeV. In situ particle measurements show that: (1) The profiles of the proton fluxes are highly dependent on the locations of their solar sources, namely flares or coronal mass ejections (CMEs), which confirms the “heliolongitude rules” associated with solar energetic particle fluxes; (2) The solar particle release (SPR) times fall in the decay phase of the flare emission, and are in accordance with the times when the CMEs travel to an average height of 7.9 solar radii; and (3) The time differences between the SPR and the flare peak are also dependent on the locations of the solar active regions. The results tend to support the scenario of proton acceleration by the CME-driven shock, even though there exists a possibility of particle acceleration at the flare site, with subsequent perpendicular diffusion of accelerated particles in the interplanetary magnetic field. We derive the integral time-of-maximum spectra of solar protons in two forms: a single power-law distribution and a power law roll-over with an exponential tail. It is found that the unique ground level enhancement that occurred in the event on 2012 May 17 displays the hardest spectrum and the largest roll-over energy which may explain why this event could extend to relativistic energies. Supported by the National Natural Science Foundation of China.

  10. Continuous Registration of Membrane Input Resistances of Small Plant Cells Using a Double-Pulse Current Clamp Technique for Single-Electrode Impalements 12

    PubMed Central

    Schefczik, Kurt; Simonis, Wilhelm; Schiebe, Michael

    1983-01-01

    To measure the cell input resistance in Elodea leaf cells, a new single-microelectrode method was explored by comparing the results with conventional two-microelectrode experiments. The new method takes advantage of the difference in the frequency response curves between electrode and cell impedances. By application of electrical stimuli, which contain specific frequency bands, the different impedances can be analyzed separately. To get a distinct separation in the frequency response of cell and electrode, respectively, the electrode capacitance has to be compensated during the impalement. Different time constants of the cell membrane can be accounted for by adjustment of the stimulus length. It is shown that both the single- and the double-electrode method yield the same results, even if the cell input resistances change considerably during the course of the experiment. This demonstrates the usefulness of the new single-electrode method for continuous measurements of cell membrane resistances, especially in cells so small that the double-electrode method is no longer applicable. Images Fig. 4 Fig. 2 PMID:16663008

  11. Current status of active surveillance in prostate cancer

    PubMed Central

    Chung, Mun Su

    2016-01-01

    Active surveillance (AS) is a management strategy involving close monitoring the course of disease with the expectation to intervene if the cancer progress, in a super-selected group of low-risk prostate cancer (PCa) patients. Determining AS candidates should be based on careful individualized weighing of numerous factors: life expectancy, general health condition, disease characteristics, potential side effects of treatment, and patient preference. Several protocols have been developed to determine insignificant PCa for choosing ideal AS candidates. Results regarding disease reclassification during AS have been also reported. In an effort to enhance accuracy during selection of AS candidate, there were several reports on using magnetic resonance imaging for prediction of insignificant PCa. Currently, there is an urgent need for further clinical studies regarding the criteria for recommending AS, the criteria for reclassification on AS, and the schedule for AS. Considering the racial differences in behavior of PCa between Western and Asian populations, more stringent AS protocols for Asian patients should be established from additional, well-designed, large clinical studies. PMID:26966722

  12. Low noise signal-to-noise ratio enhancing readout circuit for current-mediated active pixel sensors

    SciTech Connect

    Ottaviani, Tony; Karim, Karim S.; Nathan, Arokia; Rowlands, John A.

    2006-05-15

    Diagnostic digital fluoroscopic applications continuously expose patients to low doses of x-ray radiation, posing a challenge to both the digital imaging pixel and readout electronics when amplifying small signal x-ray inputs. Traditional switch-based amorphous silicon imaging solutions, for instance, have produced poor signal-to-noise ratios (SNRs) at low exposure levels owing to noise sources from the pixel readout circuitry. Current-mediated amorphous silicon pixels are an improvement over conventional pixel amplifiers with an enhanced SNR across the same low-exposure range, but whose output also becomes nonlinear with increasing dosage. A low-noise SNR enhancing readout circuit has been developed that enhances the charge gain of the current-mediated active pixel sensor (C-APS). The solution takes advantage of the current-mediated approach, primarily integrating the signal input at the desired frequency necessary for large-area imaging, while adding minimal noise to the signal readout. Experimental data indicates that the readout circuit can detect pixel outputs over a large bandwidth suitable for real-time digital diagnostic x-ray fluoroscopy. Results from hardware testing indicate that the minimum achievable C-APS output current that can be discerned at the digital fluoroscopic output from the enhanced SNR readout circuit is 0.341 nA. The results serve to highlight the applicability of amorphous silicon current-mediated pixel amplifiers for large-area flat panel x-ray imagers.

  13. Sea surface temperatures from the southern Benguela region from the Pliocene and Pleistocene: tracking Agulhas Current input into the SE Atlantic

    NASA Astrophysics Data System (ADS)

    Petrick, B. F.; McClymont, E.; Felder, S.; Lloyd, J. M.; Leng, M. J.

    2011-12-01

    The Pliocene and-Pleistocene epochs provide a way to understand the effect of past climate changes on key ocean currents. Here, we show results from ODP Site1087 (31.28'S, 15.19'E, 1374m water depth) to investigate changes in ocean circulation over the period of the mid-Pliocene warm period 3.0-3.5 Ma and compare these to the time of the 100 kyr Pleistocene glacial cycles. ODP 1087 is located in the South-eastern Atlantic Ocean, outside of the Benguela upwelling region; reconstructing the temperature history of the site will therefore provide an important data set from a part of the ocean that has few orbital-scale and continuous Pliocene temperature reconstructions. ODP 1087 can be used to investigate the history of the heat and salt transfer to the Atlantic Ocean from the Indian Ocean via the Agulhas Retroflection, which plays an important part in the global thermohaline circulation (Lutjeharms, 2007). Climate models and reconstructions for the most recent glacial-interglacial cycles have shown that changes to the strength of the heat transfer may cause major climatic changes and may play a role in transitions from glacial to interglacial events (Knorr & Lohmann, 2003). It is unknown how this transfer reacted to generally warmer global temperatures during the mid-Pliocene. Because the mid-Pliocene is seen as a model for future climate change it might provide a model for ocean circulations in a warmer world. Our approach is to apply several organic geochemistry proxies and foraminiferal analyses to reconstruct the history of ODP 1087. The UK37' index records differences in the unsaturated bonds in the C37 alkenones to reconstruct sea surface temperatures (Brassell et al., 1986). We present SSTs generated for the mid-Pliocene Warm period with a resolution of 4000 years. We compare this data to the time of the 100 kyr glacial cycles during the late Pleistocene. Even though ODP 1087 is located outside the Benguela upwelling system, it has lower Pliocene temperatures

  14. Integration of Canal and Otolith Inputs by Central Vestibular Neurons Is Subadditive for Both Active and Passive Self-Motion: Implication for Perception

    PubMed Central

    Carriot, Jerome; Jamali, Mohsen; Brooks, Jessica X.

    2015-01-01

    Traditionally, the neural encoding of vestibular information is studied by applying either passive rotations or translations in isolation. However, natural vestibular stimuli are typically more complex. During everyday life, our self-motion is generally not restricted to one dimension, but rather comprises both rotational and translational motion that will simultaneously stimulate receptors in the semicircular canals and otoliths. In addition, natural self-motion is the result of self-generated and externally generated movements. However, to date, it remains unknown how information about rotational and translational components of self-motion is integrated by vestibular pathways during active and/or passive motion. Accordingly, here, we compared the responses of neurons at the first central stage of vestibular processing to rotation, translation, and combined motion. Recordings were made in alert macaques from neurons in the vestibular nuclei involved in postural control and self-motion perception. In response to passive stimulation, neurons did not combine canal and otolith afferent information linearly. Instead, inputs were subadditively integrated with a weighting that was frequency dependent. Although canal inputs were more heavily weighted at low frequencies, the weighting of otolith input increased with frequency. In response to active stimulation, neuronal modulation was significantly attenuated (∼70%) relative to passive stimulation for rotations and translations and even more profoundly attenuated for combined motion due to subadditive input integration. Together, these findings provide insights into neural computations underlying the integration of semicircular canal and otolith inputs required for accurate posture and motor control, as well as perceptual stability, during everyday life. PMID:25716854

  15. Current radar responsive tag development activities at Sandia National Laboratories.

    SciTech Connect

    Plummer, Kenneth W.; Ormesher, Richard C.

    2003-09-01

    Over the past ten years, Sandia has developed RF radar responsive tag systems and supporting technologies for various government agencies and industry partners. RF tags can function as RF transmitters or radar transponders that enable tagging, tracking, and location determination functions. Expertise in tag architecture, microwave and radar design, signal analysis and processing techniques, digital design, modeling and simulation, and testing have been directly applicable to these tag programs. In general, the radar responsive tag designs have emphasized low power, small package size, and the ability to be detected by the radar at long ranges. Recently, there has been an interest in using radar responsive tags for Blue Force tracking and Combat ID (CID). The main reason for this interest is to allow airborne surveillance radars to easily distinguish U.S. assets from those of opposing forces. A Blue Force tracking capability would add materially to situational awareness. Combat ID is also an issue, as evidenced by the fact that approximately one-quarter of all U.S. casualties in the Gulf War took the form of ground troops killed by friendly fire. Because the evolution of warfare in the intervening decade has made asymmetric warfare the norm rather than the exception, swarming engagements in which U.S. forces will be freely intermixed with opposing forces is a situation that must be anticipated. Increasing utilization of precision munitions can be expected to drive fires progressively closer to engaged allied troops at times when visual de-confliction is not an option. In view of these trends, it becomes increasingly important that U.S. ground forces have a widely proliferated all-weather radar responsive tag that communicates to all-weather surveillance. The purpose of this paper is to provide an overview of the recent, current, and future radar responsive research and development activities at Sandia National Laboratories that support both the Blue Force Tracking

  16. Ketamine Strengthens CRF-Activated Amygdala Inputs to Basal Dendrites in mPFC Layer V Pyramidal Cells in the Prelimbic but not Infralimbic Subregion, A Key Suppressor of Stress Responses.

    PubMed

    Liu, Rong-Jian; Ota, Kristie T; Dutheil, Sophie; Duman, Ronald S; Aghajanian, George K

    2015-08-01

    A single sub-anesthetic dose of ketamine, a short-acting NMDA receptor blocker, induces a rapid and prolonged antidepressant effect in treatment-resistant major depression. In animal models, ketamine (24 h) reverses depression-like behaviors and associated deficits in excitatory postsynaptic currents (EPSCs) generated in apical dendritic spines of layer V pyramidal cells of medial prefrontal cortex (mPFC). However, little is known about the effects of ketamine on basal dendrites. The basal dendrites of layer V cells receive an excitatory input from pyramidal cells of the basolateral amygdala (BLA), neurons that are activated by the stress hormone CRF. Here we found that CRF induces EPSCs in PFC layer V cells and that ketamine enhanced this effect through the mammalian target of rapamycin complex 1 synaptogenic pathway; the CRF-induced EPSCs required an intact BLA input and were generated primarily in basal dendrites. In contrast to its detrimental effects on apical dendritic structure and function, chronic stress did not induce a loss of CRF-induced EPSCs in basal dendrites, thereby creating a relative imbalance in favor of amygdala inputs. The effects of ketamine were complex: ketamine enhanced apical EPSC responses in all mPFC subregions, anterior cingulate (AC), prelimbic (PL), and infralimbic (IL) but enhanced CRF-induced EPSCs only in AC and PL-responses were unchanged in IL, a critical area for suppression of stress responses. We propose that by restoring the strength of apical inputs relative to basal amygdala inputs, especially in IL, ketamine would ameliorate the hypothesized disproportional negative influence of the amygdala in chronic stress and major depression. PMID:25759300

  17. Active current management for four-rail railguns

    SciTech Connect

    Beno, J.H. ); Weldon, W.F. . Center for Electromechanics)

    1991-01-01

    In this paper a system of auxiliary conductors designed to reduce current density peaks in railgun rails for four-rail, round-bore railguns is described. The effects on rail current density and projectile force are discussed. Railgun cross-sectional designs are presented for round-bore, four-rail railguns which operate at lower peak current densities and develop greater projectile forces than conventional two-rail, round-bore railguns.

  18. Estimating nonstationary input signals from a single neuronal spike train

    NASA Astrophysics Data System (ADS)

    Kim, Hideaki; Shinomoto, Shigeru

    2012-11-01

    Neurons temporally integrate input signals, translating them into timed output spikes. Because neurons nonperiodically emit spikes, examining spike timing can reveal information about input signals, which are determined by activities in the populations of excitatory and inhibitory presynaptic neurons. Although a number of mathematical methods have been developed to estimate such input parameters as the mean and fluctuation of the input current, these techniques are based on the unrealistic assumption that presynaptic activity is constant over time. Here, we propose tracking temporal variations in input parameters with a two-step analysis method. First, nonstationary firing characteristics comprising the firing rate and non-Poisson irregularity are estimated from a spike train using a computationally feasible state-space algorithm. Then, information about the firing characteristics is converted into likely input parameters over time using a transformation formula, which was constructed by inverting the neuronal forward transformation of the input current to output spikes. By analyzing spike trains recorded in vivo, we found that neuronal input parameters are similar in the primary visual cortex V1 and middle temporal area, whereas parameters in the lateral geniculate nucleus of the thalamus were markedly different.

  19. Activation and adaptation of transducer currents in turtle hair cells.

    PubMed

    Crawford, A C; Evans, M G; Fettiplace, R

    1989-12-01

    1. Transducer currents were recorded in turtle cochlear hair cells during mechanical stimulation of the hair bundle. The currents were measured under whole-cell voltage clamp in isolated cells that were firmly stuck to the floor of the recording chamber. 2. Stimuli were calibrated by projecting the image of the hair bundle onto a rapidly scanned 128 photodiode array. This technique showed that, while the cell body was immobilized, the tip of the bundle would follow faithfully the motion of an attached glass probe up to frequencies of more than 1 kHz. 3. The relationship between inward transducer current and bundle displacement was sigmoidal. Maximum currents of 200-400 pA were observed for deflections of the tip of the bundle of 0.5 microns, equivalent to rotating the bundle by about 5 deg. 4. In response to a step deflection of the bundle, the current developed with a time constant (about 0.4 ms for small stimuli) that decreased with the size of displacement. This suggests that the onset of the current was limited by the gating kinetics of the transduction channel. The onset time course was slowed about fourfold for a 20 degrees C drop in temperature. 5. For small maintained displacements, the current relaxed to about a quarter of the peak level with a time constant of 3-5 ms. This adaptation was associated with a shift of the current-displacement relationship in the direction of the stimulus. The rate and extent of adaptation were decreased by lowering external Ca2+. 6. Adaptation was strongly voltage sensitive, and was abolished at holding potentials positive to the reversal potential of the transducer current of about 0 mV. It was also diminished by loading cells with 10 mM of the Ca2+ chelator BAPTA. These observations suggest that adaptation may be partly controlled by influx of Ca2+ through the transducer channels. 7. Removal of adaptation produced asymmetric responses, with fast onsets but slow decays following return of the bundle to its resting position

  20. Past challenges faced: An overview of current educational activities of IUTOX

    SciTech Connect

    Dybing, Erik . E-mail: erik.dybing@fhi.no; MacGregor, Judith; Malmfors, Torbjoern; Chipman, J. Kevin; Wright, Paul

    2005-09-01

    Over the past decade, educational programmes have been the main focus of the activities of the International Union of Toxicology (IUTOX). The IUTOX educational programmes are dynamic and have been growing in scope and frequency each year. It is envisaged that this growth will continue with guidance from our member societies and the continuing support of our sponsors. Presently, IUTOX is engaged in the following educational programmes: (1) International congresses that provide the opportunity for direct communication of current toxicological information. Fellowships are sponsored to facilitate attendance at these congresses for toxicologists in need. (2) Workshops that permit interaction on a more localised level of topics of more regional interest. Workshops have served to help stimulate formation of toxicology societies by bringing together sufficient scientists to facilitate these discussions. (3) Continuing educational (CE) programmes at member society meetings. Topics are prioritised based on input received from the local societies. Programmes often are those from CE courses given at meetings, such as conferences of the US Society of Toxicology (US SOT) and EUROTOX from the previous year. (4) Biennial Risk Assessment Summer School (RASS), an intensive week-long interaction between senior toxicologists who serve as faculty with attendees providing individual training. (5) Dissemination of donated printed toxicological books from publishers and syllabi from continuing education courses to regional locations. (6) Web-based interactive training programmes in regions where formal toxicological educational programmes are limited or lacking. (7) Preparation and distribution of monographs on selected topics of very current interest. Monographs on environmental oestrogens and genetically-modified foods have been published. The recent activities in each of these programmes are reviewed in this paper.

  1. Wastewater and Saltwater: Studying the Biogeochemistry and Microbial Activity Associated with Wastewater Inputs to San Francisco Bay

    NASA Astrophysics Data System (ADS)

    Challenor, T.; Menendez, A. D.; Damashek, J.; Francis, C. A.; Casciotti, K. L.

    2014-12-01

    Nitrification is the process of converting ammonium (NH­­4+) into nitrate (NO3-), and is a crucial step in removing nitrogen (N) from aquatic ecosystems. This process is governed by ammonia-oxidizing bacteria (AOB) and archaea (AOA) that utilize the ammonia monooxygenase gene (amoA). Studying the rates of nitrification and the abundances of ammonia-oxidizing microorganisms in south San Francisco Bay's Artesian Slough, which receives treated effluent from the massive San Jose-Santa Clara Regional Wastewater Facility, are important for understanding the cycling of nutrients in this small but complex estuary. Wastewater inputs can have negative environmental impacts, such as the release of nitrous oxide, a byproduct of nitrification and a powerful greenhouse gas. Nutrient inputs can also increase productivity and sometimes lead to oxygen depletion. Assessing the relative abundance and diversity of AOA and AOB, along with measuring nitrification rates gives vital information about the biology and biogeochemistry of this important N-cycling process. To calculate nitrification rates, water samples were spiked with 15N-labeled ammonium and incubated in triplicate for 24 hours. Four time-points were extracted across the incubation and the "denitrifier" method was used to measure the isotopic ratio of nitrate in the samples over time. In order to determine relative ratios of AOB to AOA, DNA was extracted from water samples and used in clade-specific amoA PCR assays. Nitrification rates were detectable in all locations sampled and were higher than in other regions of the bay, as were concentrations of nitrate and ammonium. Rates were highest in the regions of Artesian Slough most directly affected by wastewater effluent. AOB vastly outnumbered AOA, which is consistent with other studies showing that AOB prefer high nutrient environments. AOB diversity includes clades of Nitrosospira and Nitrosomonas prevalent in estuarine settings. Many of the sequenced genes are related

  2. Akt-mTORC1 signaling regulates Acly to integrate metabolic input to control of macrophage activation

    PubMed Central

    Covarrubias, Anthony J; Aksoylar, Halil Ibrahim; Yu, Jiujiu; Snyder, Nathaniel W; Worth, Andrew J; Iyer, Shankar S; Wang, Jiawei; Ben-Sahra, Issam; Byles, Vanessa; Polynne-Stapornkul, Tiffany; Espinosa, Erika C; Lamming, Dudley; Manning, Brendan D; Zhang, Yijing; Blair, Ian A; Horng, Tiffany

    2016-01-01

    Macrophage activation/polarization to distinct functional states is critically supported by metabolic shifts. How polarizing signals coordinate metabolic and functional reprogramming, and the potential implications for control of macrophage activation, remains poorly understood. Here we show that IL-4 signaling co-opts the Akt-mTORC1 pathway to regulate Acly, a key enzyme in Ac-CoA synthesis, leading to increased histone acetylation and M2 gene induction. Only a subset of M2 genes is controlled in this way, including those regulating cellular proliferation and chemokine production. Moreover, metabolic signals impinge on the Akt-mTORC1 axis for such control of M2 activation. We propose that Akt-mTORC1 signaling calibrates metabolic state to energetically demanding aspects of M2 activation, which may define a new role for metabolism in supporting macrophage activation. DOI: http://dx.doi.org/10.7554/eLife.11612.001 PMID:26894960

  3. Mobile input device type, texting style and screen size influence upper extremity and trapezius muscle activity, and cervical posture while texting.

    PubMed

    Kietrys, David M; Gerg, Michael J; Dropkin, Jonathan; Gold, Judith E

    2015-09-01

    This study aimed to determine the effects of input device type, texting style, and screen size on upper extremity and trapezius muscle activity and cervical posture during a short texting task in college students. Users of a physical keypad produced greater thumb, finger flexor, and wrist extensor muscle activity than when texting with a touch screen device of similar dimensions. Texting on either device produced greater wrist extensor muscle activity when texting with 1 hand/thumb compared with both hands/thumbs. As touch screen size increased, more participants held the device on their lap, and chose to use both thumbs less. There was also a trend for greater finger flexor, wrist extensor, and trapezius muscle activity as touch screen size increased, and for greater cervical flexion, although mean differences for cervical flexion were small. Future research can help inform whether the ergonomic stressors observed during texting are associated with musculoskeletal disorder risk. PMID:25959323

  4. Terrigenous input off northern South America driven by changes in Amazonian climate and the North Brazil Current retroflection during the last 250 ka

    NASA Astrophysics Data System (ADS)

    Govin, A.; Chiessi, C. M.; Zabel, M.; Sawakuchi, A. O.; Heslop, D.; Hörner, T.; Zhang, Y.; Mulitza, S.

    2013-10-01

    We investigate changes in the delivery and oceanic transport of Amazon sediments related to terrestrial climate variations over the last 250 ka. We present high-resolution geochemical records from four marine sediment cores located between 5 and 12° N along the northern South American margin. The Amazon River is the sole source of terrigenous material for sites at 5 and 9° N, while the core at 12° N receives a mixture of Amazon and Orinoco detrital particles. Using an endmember unmixing model, we estimated the relative proportions of Amazon Andean material ("%-Andes", at 5 and 9° N) and of Amazon material ("%-Amazon", at 12° N) within the terrigenous fraction. The %-Andes and %-Amazon records exhibit significant precessional variations over the last 250 ka that are more pronounced during interglacials in comparison to glacial times. High %-Andes values observed during periods of high austral summer insolation reflect the increased delivery of suspended sediments by Andean tributaries and enhanced Amazonian precipitation, in agreement with western Amazonian speleothem records. However, low %-Amazon values obtained at 12° N during the same periods seem to contradict the increased delivery of Amazon sediments. We propose that reorganisations in surface ocean currents modulate the northwestward transport of Amazon material. In agreement with published records, the seasonal North Brazil Current retroflection is intensified (or prolonged in duration) during cold substages of the last 250 ka (which correspond to intervals of high DJF or low JJA insolation) and deflects eastward the Amazon sediment and freshwater plume.

  5. Re-Mediating Current Activity for the Future

    ERIC Educational Resources Information Center

    Gutierrez, Kris D.

    2012-01-01

    The growing poverty and inequity in America should create a sense of urgency in researchers to leverage what they know for the public good--to intervene more productively and vigorously in an ever more fragile public educational system and to address the increasing vulnerability of far too many youth in the United States. The current worldwide…

  6. A National Perspective on the Current Evaluation Activities in Extension

    ERIC Educational Resources Information Center

    Lamm, Alexa J.; Israel, Glenn D.; Diehl, David

    2013-01-01

    In order to enhance Extension evaluation efforts it is important to understand current practices. The study reported here researched the evaluation behaviors of county-based Extension professionals. Extension professionals from eight states (n = 1,173) responded to a survey regarding their evaluation data collection, analysis, and reporting…

  7. Active current gating in electrically biased conical nanopores

    NASA Astrophysics Data System (ADS)

    Bearden, Samuel; Simpanen, Erik; Zhang, Guigen

    2015-05-01

    We observed that the ionic current through a gold/silicon nitride (Si3N4) nanopore could be modulated and gated by electrically biasing the gold layer. Rather than employing chemical modification to alter device behavior, we achieved control of conductance directly by electrically biasing the gold portion of the nanopore. By stepping through a range of bias potentials under a constant trans-pore electric field, we observed a gating phenomenon in the trans-pore current response in a variety of solutions including potassium chloride (KCl), sodium chloride (NaCl), and potassium iodide (KI). A computational model with a conical nanopore was developed to examine the effect of the Gouy-Chapman-Stern electrical double layer along with nanopore geometry, work function potentials, and applied electrical bias on the ionic current. The numerical results indicated that the observed modulation and gating behavior was due to dynamic reorganization of the electrical double layer in response to changes in the electrical bias. Specifically, in the conducting state, the nanopore conductance (both numerical and experimental) is linearly proportional to the applied bias due to accumulation of charge in the diffuse layer. The gating effect occurs due to the asymmetric charge distribution in the fluid induced by the distribution of potentials at the nanopore surface. Time dependent changes in current due to restructuring of the electrical double layer occur when the electrostatic bias is instantaneously changed. The nanopore device demonstrates direct external control over nanopore behavior via modulation of the electrical double layer by electrostatic biasing.

  8. A Laboratory Activity on the Eddy Current Brake

    ERIC Educational Resources Information Center

    Molina-Bolivar, J. A.; Abella-Palacios, A. J.

    2012-01-01

    The aim of this paper is to introduce a simple and low-cost experimental setup that can be used to study the eddy current brake, which considers the motion of a sliding magnet on an inclined conducting plane in terms of basic physical principles. We present a set of quantitative experiments performed to study the influence of the geometrical and…

  9. Get Current: Switch on Clean Energy Activity Book

    SciTech Connect

    2014-06-01

    Switching on clean energy technologies means strengthening the economy while protecting the environment. This activity book for all ages promotes energy awareness, with facts on different types of energy and a variety of puzzles in an energy theme.

  10. Terrigenous input off northern South America driven by changes in Amazonian climate and the North Brazil Current retroflection during the last 250 ka

    NASA Astrophysics Data System (ADS)

    Govin, A.; Chiessi, C. M.; Zabel, M.; Sawakuchi, A. O.; Heslop, D.; Hörner, T.; Zhang, Y.; Mulitza, S.

    2014-04-01

    We investigate changes in the delivery and oceanic transport of Amazon sediments related to terrestrial climate variations over the last 250 ka. We present high-resolution geochemical records from four marine sediment cores located between 5 and 12° N along the northern South American margin. The Amazon River is the sole source of terrigenous material for sites at 5 and 9° N, while the core at 12° N receives a mixture of Amazon and Orinoco detrital particles. Using an endmember unmixing model, we estimated the relative proportions of Amazon Andean material ("%-Andes", at 5 and 9° N) and of Amazon material ("%-Amazon", at 12° N) within the terrigenous fraction. The %-Andes and %-Amazon records exhibit significant precessional variations over the last 250 ka that are more pronounced during interglacials in comparison to glacial periods. High %-Andes values observed during periods of high austral summer insolation reflect the increased delivery of suspended sediments by Andean tributaries and enhanced Amazonian precipitation, in agreement with western Amazonian speleothem records. Increased Amazonian rainfall reflects the intensification of the South American monsoon in response to enhanced land-ocean thermal gradient and moisture convergence. However, low %-Amazon values obtained at 12° N during the same periods seem to contradict the increased delivery of Amazon sediments. We propose that reorganizations in surface ocean currents modulate the northwestward transport of Amazon material. In agreement with published records, the seasonal North Brazil Current retroflection is intensified (or prolonged in duration) during cold substages of the last 250 ka (which correspond to intervals of high DJF or low JJA insolation) and deflects eastward the Amazon sediment and freshwater plume.

  11. Enhancing the fidelity of neurotransmission by activity-dependent facilitation of presynaptic potassium currents.

    PubMed

    Yang, Yi-Mei; Wang, Wei; Fedchyshyn, Michael J; Zhou, Zhuan; Ding, Jiuping; Wang, Lu-Yang

    2014-01-01

    Neurons convey information in bursts of spikes across chemical synapses where the fidelity of information transfer critically depends on synaptic input-output relationship. With a limited number of synaptic vesicles (SVs) in the readily releasable pool (RRP), how nerve terminals sustain transmitter release during intense activity remains poorly understood. Here we report that presynaptic K(+) currents evoked by spikes facilitate in a Ca(2+)-independent but frequency- and voltage-dependent manner. Experimental evidence and computer simulations demonstrate that this facilitation originates from dynamic transition of intermediate gating states of voltage-gated K(+) channels (Kvs), and specifically attenuates spike amplitude and inter-spike potential during high-frequency firing. Single or paired recordings from a mammalian central synapse further reveal that facilitation of Kvs constrains presynaptic Ca(2+) influx, thereby efficiently allocating SVs in the RRP to drive postsynaptic spiking at high rates. We conclude that presynaptic Kv facilitation imparts neurons with a powerful control of transmitter release to dynamically support high-fidelity neurotransmission. PMID:25078759

  12. Root carbon inputs to the rhizosphere stimulate extracellular enzyme activity and increase nitrogen availability in temperate forest soils

    NASA Astrophysics Data System (ADS)

    Brzostek, E. R.; Phillips, R.; Dragoni, D.; Drake, J. E.; Finzi, A. C.

    2011-12-01

    The mobilization of nitrogen (N) from soil organic matter in temperate forest soils is controlled by the microbial production and activity of extracellular enzymes. The exudation of carbon (C) by tree roots into the rhizosphere may subsidize the microbial production of extracellular enzymes in the rhizosphere and increase the access of roots to N. The objective of this research was to investigate whether rates of root exudation and the resulting stimulation of extracellular enzyme activity in the rhizosphere (i.e., rhizosphere effect) differs between tree species that form associations with ectomycorrhizal (ECM) or arbuscular mycorrhizal (AM) fungi. This research was conducted at two temperate forest sites, the Harvard Forest (HF) in Central MA and the Morgan Monroe State Forest (MMSF) in Southern IN. At the HF, we measured rates of root exudation and the rhizosphere effects on enzyme activity, N cycling, and C mineralization in AM and ECM soils. At the MMSF, we recently girdled AM and ECM dominated plots to examine the impact of severing belowground C allocation on rhizosphere processes. At both sites, the rhizosphere effect on proteolytic, chitinolytic and ligninolytic enzyme activities was greater in ECM soils than in AM soils. In particular, higher rates of proteolytic enzyme activity increased the availability of amino acid-N in ECM rhizospheres relative to the bulk soils. Further, this stimulation of enzyme activity was directly correlated with higher rates of C mineralization in the rhizosphere than in the bulk soil. Although not significantly different between species, root exudation of C comprised 3-10% of annual gross primary production at the HF. At the MMSF, experimental girdling led to a larger decline in soil respiration and enzyme activity in ECM plots than in AM plots. In both ECM and AM soils, however, girdling resulted in equivalent rates of enzyme activity in rhizosphere and corresponding bulk soils. The results of this study contribute to the

  13. Effects of ankle extensor muscle afferent inputs on hip abductor and adductor activity in the decerebrate walking cat.

    PubMed

    Bolton, D A E; Misiaszek, J E

    2012-12-01

    Electrical stimulation of the lateral gastrocnemius-soleus (LGS) nerve at group I afferent strength leads to adaptations in the amplitude and timing of extensor muscle activity during walking in the decerebrate cat. Such afferent feedback in the stance leg might result from a delay in stance onset of the opposite leg. Concomitant adaptations in hip abductor and adductor activity would then be expected to maintain lateral stability and balance until the opposite leg is able to support the body. As many hip abductors and adductors are also hip extensors, we hypothesized that stimulation of the LGS nerve at group I afferent strength would produce increased activation and prolonged burst duration in hip abductor and adductor muscles in the premammillary decerebrate walking cat. LGS nerve stimulation during the extensor phase of the locomotor cycle consistently increased burst amplitude of the gluteus medius and adductor femoris muscles, but not pectineus or gracilis. In addition, LGS stimulation prolonged the burst duration of both gluteus medius and adductor femoris. Unexpectedly, long-duration LGS stimulus trains resulted in two distinct outcomes on the hip abductor and adductor bursting pattern: 1) a change of burst duration and timing similar to medial gastrocnemius; or 2) to continue rhythmically bursting uninterrupted. These results indicate that activation of muscle afferents from ankle extensors contributes to the regulation of activity of some hip abductor and adductor muscles, but not all. These results have implications for understanding the neural control of stability during locomotion, as well as the organization of spinal locomotor networks. PMID:22972967

  14. Ca2+ current and Ca(2+)-activated chloride current in isolated smooth muscle cells of the sheep urethra.

    PubMed Central

    Cotton, K D; Hollywood, M A; McHale, N G; Thornbury, K D

    1997-01-01

    1. Isolated sheep urethral cells were studied using the perforated patch clamp technique (T = 37 degrees C). Depolarizing steps ranging from -40 to -10 mV evoked an inward current that peaked within 10 ms and a slower inward current. Stepping back to the holding potential of -80 mV evoked large inward tail currents. All three currents were abolished by nifedipine (1 microM). Substitution of external Ca2+ with Ba2+ resulted in potentiation of the fast inward current and blockade of the slow current and tails. 2. Changing the chloride equilibrium potential (ECl) from 0 to +27 mV shifted the reversal potential of the tail currents from 1 +/- 1 to 27 +/- 1 mV (number of cells, n = 5). Chloride channel blockers, niflumic acid (10 microM) and anthracene-9-carboxylic acid (9AC, 1 mM), reduced the slow current and tails suggesting that these were Ca(2+)-activated Cl- currents, ICl(Ca). 4. Caffeine (10 mM) induced currents that reversed at ECl and were blocked by niflumic acid (10 microM). 5. In current clamp mode, some cells developed spontaneous transient depolarizations (STDs) and action potentials. Short exposure to nifedipine blocked the action potentials and unmasked STDs. In contrast, 9AC and niflumic acid reduced the amplitude of the STDs and blocked the action potentials. 6. In conclusion, these cells have both L-type ICa and ICl(Ca). The former appears to be responsible for the upstroke of the action potential, while the latter may act as a pacemaker current. PMID:9409476

  15. Current water resources activities in Arkansas, 1984-85

    USGS Publications Warehouse

    Louthian, B.L.; Gann, E.E.

    1985-01-01

    This report describes water resources activities conducted by the Arkansas District of the U.S. Geological Survey, Water Resources Division, during fiscal years 1984 and 1985. Activities included surface water, groundwater, water quality, and water-use investigations. Twenty-five projects were funded during 1984 and 1985. For each project, a description of the project objectives, approach, plans and reports is included. Lists are included of reports completed during the period and of reports previously published by, or in conjunction with the Geological Survey. (USGS)

  16. Current water resources activities in Arkansas, 1986-87

    USGS Publications Warehouse

    Louthian, B.L.; Gann, E.E.

    1988-01-01

    This report describes water resources activities conducted by the Arkansas District of the U.S. Geological Survey, Water Resources Division during fiscal years 1986 and 1987. Activities included surface water, groundwater, water quality, and water-use investigations. Eighteen projects were funded during 1986 and 1987. For each project, a description of the project objectives, approach, plans and reports is included. Lists are included of reports completed during the period and of reports previously published by, or in conjunction with, the Geological Survey. (USGS)

  17. Mechanotransduction and hyperpolarization-activated currents contribute to spontaneous activity in mouse vestibular ganglion neurons.

    PubMed

    Horwitz, Geoffrey C; Risner-Janiczek, Jessica R; Holt, Jeffrey R

    2014-04-01

    The hyperpolarization-activated, cyclic nucleotide-sensitive current, Ih, is present in vestibular hair cells and vestibular ganglion neurons, and is required for normal balance function. We sought to identify the molecular correlates and functional relevance of Ih in vestibular ganglion neurons. Ih is carried by channels consisting of homo- or heteromeric assemblies of four protein subunits from the Hcn gene family. The relative expression of Hcn1-4 mRNA was examined using a quantitative reverse transcription PCR (RT-PCR) screen. Hcn2 was the most highly expressed subunit in vestibular neuron cell bodies. Immunolocalization of HCN2 revealed robust expression in cell bodies of all vestibular ganglion neurons. To characterize Ih in vestibular neuron cell bodies and at hair cell-afferent synapses, we developed an intact, ex vivo preparation. We found robust physiological expression of Ih in 89% of cell bodies and 100% of calyx terminals. Ih was significantly larger in calyx terminals than in cell bodies; however, other biophysical characteristics were similar. Ih was absent in calyces lacking Hcn1 and Hcn2, but small Ih was still present in cell bodies, which suggests expression of an additional subunit, perhaps Hcn4. To determine the contributions of hair cell mechanotransduction and Ih to the firing patterns of calyx terminals, we recorded action potentials in current-clamp mode. Mechanotransduction currents were modulated by hair bundle defection and application of calcium chelators to disrupt tip links. Ih activity was modulated using ZD7288 and cAMP. We found that both hair cell transduction and Ih contribute to the rate and regularity of spontaneous action potentials in the vestibular afferent neurons. We propose that modulation of Ih in vestibular ganglion neurons may provide a mechanism for modulation of spontaneous activity in the vestibular periphery. PMID:24638995

  18. Using Ecological Momentary Assessment to Evaluate Current Physical Activity

    PubMed Central

    Marszalek, Jolanta; Morgulec-Adamowicz, Natalia; Rutkowska, Izabela; Kosmol, Andrzej

    2014-01-01

    Objective. The purpose of this study was to assess the value of ecological momentary assessment in evaluating physical activity among children, adolescents, and adults. It also determines whether ecological momentary assessment fulfills the criteria of validity, reliability, objectivity, norms, and standardization applied to the tools used for the evaluation of physical activity. Methods. The EBSCO-CINHAL, Medline, PsycINFO, PubMed, and SPORTDiscuss databases were reviewed in December 2012 for articles associated with EMA. Results. Of the 20 articles examined, half (10) used electronic methods for data collection, although various methods were used, ranging from pen and paper to smartphone applications. Ten studies used objective monitoring equipment. Nineteen studies were performed over 4 days. While the validity of the EMA method was discussed in 18 studies, only four found it to be objective. In all cases, the EMA procedures were precisely documented and confirmed to be feasible. Conclusions. Ecological momentary assessment is a valid, reliable, and feasible approach to evaluate activity and sedentary behavior. Researchers should be aware that while ecological momentary assessment offers many benefits, it simultaneously imposes many limitations which should be considered when studying physical activity. PMID:25126580

  19. Teacher Feedback during Active Learning: Current Practices in Primary Schools

    ERIC Educational Resources Information Center

    van den Bergh, Linda; Ros, Anje; Beijaard, Douwe

    2013-01-01

    Background: Feedback is one of the most powerful tools, which teachers can use to enhance student learning. It appears dif?cult for teachers to give qualitatively good feedback, especially during active learning. In this context, teachers should provide facilitative feedback that is focused on the development of meta-cognition and social learning.…

  20. ASSESSING AND MANAGING MERCURY FROM HISTORIC AND CURRENT MINING ACTIVITIES

    EPA Science Inventory

    Mining activities in the US (not counting coal) produce between one and two billion tons of mine waste annually. Since many of the ore mines involve sulfide minerals, the production of acid mine drainage (AMD) is a common problem from these abandoned mine sites. The combination o...

  1. Wall conditioning for ITER: Current experimental and modeling activities

    NASA Astrophysics Data System (ADS)

    Douai, D.; Kogut, D.; Wauters, T.; Brezinsek, S.; Hagelaar, G. J. M.; Hong, S. H.; Lomas, P. J.; Lyssoivan, A.; Nunes, I.; Pitts, R. A.; Rohde, V.; de Vries, P. C.

    2015-08-01

    Wall conditioning will be required in ITER to control fuel and impurity recycling, as well as tritium (T) inventory. Analysis of conditioning cycle on the JET, with its ITER-Like Wall is presented, evidencing reduced need for wall cleaning in ITER compared to JET-CFC. Using a novel 2D multi-fluid model, current density during Glow Discharge Conditioning (GDC) on the in-vessel plasma-facing components (PFC) of ITER is predicted to approach the simple expectation of total anode current divided by wall surface area. Baking of the divertor to 350 °C should desorb the majority of the co-deposited T. ITER foresees the use of low temperature plasma based techniques compatible with the permanent toroidal magnetic field, such as Ion (ICWC) or Electron Cyclotron Wall Conditioning (ECWC), for tritium removal between ITER plasma pulses. Extrapolation of JET ICWC results to ITER indicates removal comparable to estimated T-retention in nominal ITER D:T shots, whereas GDC may be unattractive for that purpose.

  2. [Current views on the importance of physical activity].

    PubMed

    Berg, A; Deibert, P; Berg, A; König, D; Dickhuth, H H

    2004-07-01

    To improve the individual health profile and to solve the growing overweight problem, a long-term change in the lifestyle to one which includes an energetically balanced combination of diet and activity is essential. Physical activity and the muscles involved are the primary means by which body composition and energy turnover are regulated. A state of imbalance has decisive consequences on the development of atherogenic and inflammatory risk factors. Additionally, the aging process is significantly influenced by the long-term retention or loss of muscle mass. The Deutsche Gesellschaft für Sportmedizin und Prävention (German Society for Sports Medicine and Prevention, a registered association) offers within the concept of a therapeutic lifestyle change, an educational program for overweight adults (M.O.B.I.L.I.S.). PMID:15526658

  3. Current activities within the National Biomonitoring Specimen Bank.

    PubMed

    Wise, S A; Koster, B J; Langland, J K; Zeisler, R

    1993-11-01

    The National Institute of Standards and Technology (NIST) has been involved in biological environmental specimen banking activities since 1979. These activities, which are known collectively as the National Biomonitoring Specimen Bank (NBSB), include the banking of a variety of specimens (human liver, sediment, mussels/oysters, fish tissue and marine mammal tissues) from several different projects supported by different government agencies. The two most recent projects, the Alaska Marine Mammal Tissue Archival Project (AMMTAP) and the National Marine Mammal Tissue Bank (NMMTB), focus on the collection, banking and analysis of marine mammal tissues and they are part of a comprehensive plan to address marine mammal monitoring, specimen banking and quality assurance of analytical measurements associated with contaminant analyses in marine mammals. PMID:8272819

  4. Current status of pyrazole and its biological activities

    PubMed Central

    Naim, Mohd Javed; Alam, Ozair; Nawaz, Farah; Alam, Md. Jahangir; Alam, Perwaiz

    2016-01-01

    Pyrazole are potent medicinal scaffolds and exhibit a full spectrum of biological activities. This review throws light on the detailed synthetic approaches which have been applied for the synthesis of pyrazole. This has been followed by an in depth analysis of the pyrazole with respect to their medical significance. This follow-up may help the medicinal chemists to generate new leads possessing pyrazole nucleus with high efficacy. PMID:26957862

  5. Current activities of the Yersinia effector protein YopM.

    PubMed

    Höfling, Sabrina; Grabowski, Benjamin; Norkowski, Stefanie; Schmidt, M Alexander; Rüter, Christian

    2015-05-01

    Yersinia outer protein M (YopM) belongs to the group of Yop effector proteins, which are highly conserved among pathogenic Yersinia species. During infection, the effectors are delivered into the host cell cytoplasm via the type 3 secretion system to subvert the host immune response and support the survival of Yersinia. In contrast to the other Yop effectors, YopM does not possess a known enzymatic activity and its molecular mechanism(s) of action remain(s) poorly understood. However, YopM was shown to promote colonization and dissemination of Yersinia, thus being crucial for the pathogen's virulence in vivo. Moreover, YopM interacts with several host cell proteins and might utilize them to execute its anti-inflammatory activities. The results obtained so far indicate that YopM is a multifunctional protein that counteracts the host immune defense by multiple activities, which are at least partially independent of each other. Finally, its functions seem to be also influenced by differences between the specific YopM isoforms expressed by Yersinia subspecies. In this review, we focus on the global as well as more specific contribution of YopM to virulence of Yersinia during infection and point out the various extra- and intracellular molecular functions of YopM. In addition, the novel cell-penetrating ability of recombinant YopM and its potential applications as a self-delivering immunomodulatory therapeutic will be discussed. PMID:25865799

  6. A laboratory activity on the eddy current brake

    NASA Astrophysics Data System (ADS)

    Molina-Bolívar, J. A.; Abella-Palacios, A. J.

    2012-05-01

    The aim of this paper is to introduce a simple and low-cost experimental setup that can be used to study the eddy current brake, which considers the motion of a sliding magnet on an inclined conducting plane in terms of basic physical principles. We present a set of quantitative experiments performed to study the influence of the geometrical and electromagnetic properties of the magnet on the magnetic drag force. This video-based experiment is ideal for the study of kinematic graphs and the application of Newton's laws. Video motion analysis software enables students to make precise measurements of the magnet's position at incremental times during its motion, thus allowing them to quantify electromagnetic induction phenomena. The equipment needed for this experiment and data collection software are present in most physics teaching laboratories or are inexpensive and available.

  7. Constitutive activation of myosin-dependent contractility sensitizes glioma tumor-initiating cells to mechanical inputs and reduces tissue invasion

    PubMed Central

    Wong, Sophie Y.; Ulrich, Theresa A.; Deleyrolle, Loic P.; MacKay, Joanna L.; Lin, Jung-Ming G.; Martuscello, Regina T.; Jundi, Musa A.; Reynolds, Brent A.; Kumar, Sanjay

    2015-01-01

    Tumor-initiating cells (TICs) perpetuate tumor growth, enable therapeutic resistance, and drive initiation of successive tumors. Virtually nothing is known about the role of mechanotransductive signaling in controlling TIC tumorigenesis, despite the recognized importance of altered mechanics in tissue dysplasia and the common observation that extracellular matrix (ECM) stiffness strongly regulates cell behavior. To address this open question, we cultured primary human glioblastoma (GBM) TICs on laminin-functionalized ECMs spanning a range of stiffnesses. Surprisingly, we found that these cells were largely insensitive to ECM stiffness cues, evading the inhibition of spreading, migration, and proliferation typically imposed by compliant ECMs. We hypothesize that this insensitivity may result from insufficient generation of myosin-dependent contractile force. Indeed, we found that both pharmacologic and genetic activation of cell contractility through RhoA GTPase, Rho-associated kinase (ROCK), or myosin light chain kinase (MLCK) restored stiffness-dependent spreading and motility, with TICs adopting the expected rounded and non-motile phenotype on soft ECMs. Moreover, constitutive activation of RhoA restricted three-dimensional invasion in both spheroid implantation and transwell paradigms. Orthotopic xenotransplantation studies revealed that control TICs formed tumors with classical GBM histopathology including diffuse infiltration and secondary foci, whereas TICs expressing a constitutively active mutant of RhoA produced circumscribed masses and yielded a 30% enhancement in mean survival time. This is the first direct evidence that manipulation of mechanotransductive signaling can alter the tumor-initiating capacity of GBM TICs, supporting further exploration of these signals as potential therapeutic targets and predictors of tumor initiating capacity within heterogeneous tumor cell populations. PMID:25634210

  8. Radiation processing in india-current R & D activities

    NASA Astrophysics Data System (ADS)

    Majali, A. B.; Sabharwal, S.

    1995-09-01

    Radiation processing is an area of vigorous activity in today's India. With the indigenous expertise in Co source and irradiator technology, potentially promising applications such as sustained drug delivery systems, vulcanization of natural rubber latex (RVNRL), and degradation of polytetrafluoroethylene (PTFE) are presently investigated. Over the last four years, technologies for RVNRL and PTFE degradation have been scaled upto pilot scale operations, while radiation polymerized polymer systems have been developed for controlled release of certain drugs. With the commissioning of the 2 MeV EB machine in late 1988, a few EB based processes have also been commercially exploited. The paper briefly reviews these and presents the significant results obtained.

  9. Effect of electric current frequency on the activation kinetics of raw charcoal

    SciTech Connect

    Shevchenko, A.O.; Ivakhnyuk, G.K.; Fedorov, N.F.

    1993-12-10

    The effect of electric current frequency on the kinetics of raw charcoal activation with water vapor has been investigated. It was established that under the effect of alternating current the rate constant increases under otherwise equal conditions. A dependence of the reaction rate on the current frequency was found. It was discovered that under the effect of alternating current the activation energy of interaction with water vapor diminishes.

  10. Coordinate direct input of both KRAS and IGF1 receptor to activation of PI 3-kinase in KRAS mutant lung cancer

    PubMed Central

    Molina-Arcas, Miriam; Hancock, David C.; Sheridan, Clare; Kumar, Madhu S.; Downward, Julian

    2013-01-01

    SUMMARY Using a panel of non-small cell lung cancer (NSCLC) lines, we show here that MEK and RAF inhibitors are selectively toxic for the KRAS mutant genotype, while PI 3-kinase (PI3K), AKT and mTOR inhibitors are not. IGF1 receptor (IGF1R) tyrosine kinase inhibitors also show selectivity for KRAS mutant lung cancer lines. Combinations of IGF1R and MEK inhibitors resulted in strengthened inhibition of KRAS mutant lines and also showed improved effectiveness in autochthonous mouse models of Kras induced NSCLC. PI3K pathway activity is dependent on basal IGF1R activity in KRAS mutant, but not wild-type, lung cancer cell lines. KRAS is needed for both MEK and PI3K pathway activity in KRAS mutant, but not wild-type, lung cancer cells, while acute activation of KRAS causes stimulation of PI3K dependent upon IGF1R kinase activity. Coordinate direct input of both KRAS and IGF1R is thus required to activate PI3K in KRAS mutant lung cancer cells. PMID:23454899

  11. Impact of organic and mineral inputs onto soil biological and metabolic activities under a long-term rice-wheat cropping system in sub-tropical Indian Inceptisols.

    PubMed

    Basak, Nirmalendu; Datta, Ashim; Mitran, Tarik; Mandal, Biswapati; Mani, P K

    2016-01-01

    Long-term use of organic and mineral inputs has an overriding impact on soil biological and metabolic activities and crop management. Farm yard manure (FYM), paddy straw (PS) and green manure (GM, Sesbania sesban L.) were used for 24- years old rice (Oyza sativa L.) -wheat (Triticum aestivum L.) cropping system in sub-tropical India to predict whether the screened soil biological and metabolic activities are correlated with system yield. The integrated approaches viz., NPK + FYM, NPK + PS and NPK + GM significantly increased both rice and wheat yield together by 67.5, 44.4 and 55.4%, respectively over control. However, for a few exceptions both soil microbial activity and metabolic activity were remarkably enhanced under integrated treatment NPK + FYM followed by NPK + PS, and NPK + GM, respectively. Among the studied attributes fluorescein diacetate hydrolyzing, dehydrogenase, β-glucosidase activity (β-glu) and microbial biomass C (C(mic)) were screened through principal component (PCA) and discriminate analysis (DA) that explained nearly 89% of total variations of the entire data set. Among the four identified attributes, only β-glu assay value could predict system yield (R2 = 0.65). Further, estimation of β-glu activity in soil can predict other soil biological properties (R2 = 0.96). PMID:26930864

  12. Micronuclei in lymphocytes from currently active uranium miners.

    PubMed

    Zölzer, Friedo; Hon, Zdeněk; Skalická, Zuzana Freitinger; Havránková, Renata; Navrátil, Leoš; Rosina, Jozef; Škopek, Jiří

    2012-08-01

    Micronuclei can be used as markers of past radiation exposure, but only few studies have dealt with uranium miners. In this paper, we report on micronuclei in lymphocytes from individuals currently working at Rožná, Czech Republic, the last functioning uranium mine in the European Union. A modified micronucleus-centromere test was applied to assess the occurrence of micronuclei in stimulated lymphocytes, as well as their content in terms of whole chromosomes or fragments. Compared with unexposed individuals, the miners had higher frequencies of micronucleus-containing lymphocytes and higher percentages of micronuclei without centromeres, and the differences were significant for both parameters (0.74 ± 0.60 vs. 0.50 ± 0.42, p = 0.017 and 49 ± 44 vs. 12 ± 21, p = 0.0002; means ± standard deviations). There were also significant correlations between one or other of these parameters on the one hand and various dose values on the other, in particular with a 'retrievable' dose, that is, a dose whose effect should still be recognisable in lymphocytes assuming a half-life of 3 years. The 'retrievable' dose at which a doubling of the micronucleus frequency was observed was around 35 mSv, corresponding to a total dose of 90 mSv received while working in the mines. Altogether, our data show that the micronucleus-centromere test is a valuable tool for the assessment of past radiation exposure in uranium miners. The scatter in the data is of course far too great to allow individual dosimetry, but for groups of a few dozen exposed individuals, the method can be used to monitor doses clearly below 100 mSv. PMID:22622995

  13. Effects of Auditory Input in Individuation Tasks

    ERIC Educational Resources Information Center

    Robinson, Christopher W.; Sloutsky, Vladimir M.

    2008-01-01

    Under many conditions auditory input interferes with visual processing, especially early in development. These interference effects are often more pronounced when the auditory input is unfamiliar than when the auditory input is familiar (e.g. human speech, pre-familiarized sounds, etc.). The current study extends this research by examining how…

  14. Peroxisome proliferator-activated receptor gamma (PPARγ) in brown trout: Interference of estrogenic and androgenic inputs in primary hepatocytes.

    PubMed

    Lopes, Célia; Madureira, Tânia Vieira; Ferreira, Nádia; Pinheiro, Ivone; Castro, L Filipe C; Rocha, Eduardo

    2016-09-01

    Peroxisome proliferator-activated receptor gamma (PPARγ) is a pivotal regulator of lipid and glucose metabolism in vertebrates. Here, we isolated and characterized for the first time the PPARγ gene from brown trout (Salmo trutta f. fario). Hormones have been reported to interfere with the regulatory function of PPARγ in various organisms, albeit with little focus on fish. Thus, primary hepatocytes isolated from juveniles of brown trout were exposed to 1, 10 and 50μM of ethinylestradiol (EE2) or testosterone (T). A significant (3 fold) decrease was obtained in response to 50μM of EE2 and to 10 and 50μM of T (13 and 14 folds), while a 3 fold increase was observed at 1μM of EE2. Therefore, trout PPARγ seems a target for natural/synthetic compounds with estrogenic or androgenic properties and so, we advocate considering PPARγ as another alert sensor gene when assessing the effects of sex-steroid endocrine disruptors. PMID:27541269

  15. Current trends in the structure-activity relationships of sialyltransferases.

    PubMed

    Audry, Magali; Jeanneau, Charlotte; Imberty, Anne; Harduin-Lepers, Anne; Delannoy, Philippe; Breton, Christelle

    2011-06-01

    Sialyltransferases (STs) represent an important group of enzymes that transfer N-acetylneuraminic acid (Neu5Ac) from cytidine monophosphate-Neu5Ac to various acceptor substrates. In higher animals, sialylated oligosaccharide structures play crucial roles in many biological processes but also in diseases, notably in microbial infection and cancer. Cell surface sialic acids have also been found in a few microorganisms, mainly pathogenic bacteria, and their presence is often associated with virulence. STs are distributed into five different families in the CAZy database (http://www.cazy.org/). On the basis of crystallographic data available for three ST families and fold recognition analysis for the two other families, STs can be grouped into two structural superfamilies that represent variations of the canonical glycosyltransferase (GT-A and GT-B) folds. These two superfamilies differ in the nature of their active site residues, notably the catalytic base (a histidine or an aspartate residue). The observed structural and functional differences strongly suggest that these two structural superfamilies have evolved independently. PMID:21098518

  16. Quantifying Amount and Variability of Cloud Water Inputs Using Active-Strand Collector, Ceilometer, Dewpoint, and Photographic Measurements

    NASA Astrophysics Data System (ADS)

    Scholl, M. A.; Bassiouni, M.; Murphy, S. F.; Gonzalez, G.; Van Beusekom, A. E.; Torres-Sanchez, A.; Estrada-Ruiz, C.

    2015-12-01

    Cloud water associated with orographic processes contributes to soil moisture and streamflow, suppresses transpiration, and moderates drought in tropical mountain forests. It is difficult to quantify, yet may be vulnerable to changes in amount and frequency due to warming climate. Cloud immersion is characterized and monitored as part of the ecohydrology research of the USGS Water, Energy and Biogeochemical Budgets (WEBB) program and the Luquillo Critical Zone Observatory (CZO). Stable-isotope studies indicated cloud water may contribute significantly to headwater streamflow, and measurements with an active-strand collector yielded estimates of overnight cloud water deposition rates on Pico del Este (1050 m); but cloud liquid water content and spatial and temporal variability are not well understood. At five sites spanning the lifting condensation level to ridge-top (600-1000 m) in the Luquillo Mountains, cloud immersion conditions are monitored using time-lapse photography and temperature/ relative humidity (T/RH) sensors. A ceilometer, installed at 99 m on the windward slope on 4/29/2013, provides longer-term data to understand variation in cloud base altitude and to detect changes that may occur with warming climate. The cloud-zone sites range from tropical wet forest (mixed species) to rain forest (sierra palm) to elfin cloud forest. T/RH sensors indicated foggy conditions when temperature < dewpoint, but they are not sensitive to varying water content in the cloud. Images were processed to determine frequency and duration of immersion and estimates of optical density of cloud. Spatial heterogeneity in cloud immersion is assessed by comparing ceilometer measurements to the images. These complementary data sets provide quantification of spatial and temporal patterns of cloud immersion, and areal estimates of cloud water deposition will be made to determine importance in the water budget.

  17. Voltage-activated currents recorded from rabbit pigmented ciliary body epithelial cells in culture.

    PubMed Central

    Fain, G L; Farahbakhsh, N A

    1989-01-01

    1. The whole-cell recording mode of the patch-clamp technique was used to investigate the presence of voltage-activated currents in the isolated pigmented cells from the rabbit ciliary body epithelium grown in culture. 2. In Ringer solution with composition similar to that of the rabbit aqueous humour, depolarizing voltage steps activated a transient inward current and a delayed outward current, while hyperpolarization elicited an inwardly rectified current. 3. The depolarization-activated inward current was mainly carried by Na+ and was blocked by submicromolar concentrations of tetrodotoxin. This current in many cells was sufficiently large to produce a regenerative Na+ spike. 4. The depolarization-activated outward current was carried by K+ and blocked by external TEA and Ba2+. Its activation appeared to be Ca2(+)-independent. 5. The hyperpolarization-activated inward current was almost exclusively carried by K+ and was blocked by Ba2+ and Cs+. For large hyperpolarizations below -120 mV, this current exhibited a biphasic activation with a fast transient peak followed by a slower sag, that appeared to be due to K+ depletion. 6. The voltage-dependent K+ conductances probably act to stabilize the cell membrane resting potential and may also play a role in ion transport. The function of the Na(+)-dependent inward current is unclear, but it may permit the electrically coupled epithelial cells of the ciliary body to conduct propagated action potentials. Images Fig. 2 PMID:2621623

  18. Diode laser threshold current density and lasing wavelength as functions of active region thickness

    SciTech Connect

    Streifer, W.; Scifres, D.R.; Burnham, R.D.

    1983-03-01

    Based on a simple model of the band-to-band absorption of a diode laser active region, we formulatean expression for modal gain as a function of pumping current. Using this result yields expressions for threshold current density and lasing photon energy which depend on device parameters including active region thickness, laser length, internal losses, facet reflectivity, etc.

  19. Results of community deliberation about social impacts of ecological restoration: comparing public input of self-selected versus actively engaged community members.

    PubMed

    Harris, Charles C; Nielsen, Erik A; Becker, Dennis R; Blahna, Dale J; McLaughlin, William J

    2012-08-01

    Participatory processes for obtaining residents' input about community impacts of proposed environmental management actions have long raised concerns about who participates in public involvement efforts and whose interests they represent. This study explored methods of broad-based involvement and the role of deliberation in social impact assessment. Interactive community forums were conducted in 27 communities to solicit public input on proposed alternatives for recovering wild salmon in the Pacific Northwest US. Individuals identified by fellow residents as most active and involved in community affairs ("AE residents") were invited to participate in deliberations about likely social impacts of proposed engineering and ecological actions such as dam removal. Judgments of these AE participants about community impacts were compared with the judgments of residents motivated to attend a forum out of personal interest, who were designated as self-selected ("SS") participants. While the magnitude of impacts rated by SS participants across all communities differed significantly from AE participants' ratings, in-depth analysis of results from two community case studies found that both AE and SS participants identified a large and diverse set of unique impacts, as well as many of the same kinds of impacts. Thus, inclusion of both kinds of residents resulted in a greater range of impacts for consideration in the environmental impact study. The case study results also found that the extent to which similar kinds of impacts are specified by AE and SS group members can differ by type of community. Study results caution against simplistic conclusions drawn from this approach to community-wide public participation. Nonetheless, the results affirm that deliberative methods for community-based impact assessment involving both AE and SS residents can provide a more complete picture of perceived impacts of proposed restoration activities. PMID:22615108

  20. Results of Community Deliberation About Social Impacts of Ecological Restoration: Comparing Public Input of Self-Selected Versus Actively Engaged Community Members

    NASA Astrophysics Data System (ADS)

    Harris, Charles C.; Nielsen, Erik A.; Becker, Dennis R.; Blahna, Dale J.; McLaughlin, William J.

    2012-08-01

    Participatory processes for obtaining residents' input about community impacts of proposed environmental management actions have long raised concerns about who participates in public involvement efforts and whose interests they represent. This study explored methods of broad-based involvement and the role of deliberation in social impact assessment. Interactive community forums were conducted in 27 communities to solicit public input on proposed alternatives for recovering wild salmon in the Pacific Northwest US. Individuals identified by fellow residents as most active and involved in community affairs ("AE residents") were invited to participate in deliberations about likely social impacts of proposed engineering and ecological actions such as dam removal. Judgments of these AE participants about community impacts were compared with the judgments of residents motivated to attend a forum out of personal interest, who were designated as self-selected ("SS") participants. While the magnitude of impacts rated by SS participants across all communities differed significantly from AE participants' ratings, in-depth analysis of results from two community case studies found that both AE and SS participants identified a large and diverse set of unique impacts, as well as many of the same kinds of impacts. Thus, inclusion of both kinds of residents resulted in a greater range of impacts for consideration in the environmental impact study. The case study results also found that the extent to which similar kinds of impacts are specified by AE and SS group members can differ by type of community. Study results caution against simplistic conclusions drawn from this approach to community-wide public participation. Nonetheless, the results affirm that deliberative methods for community-based impact assessment involving both AE and SS residents can provide a more complete picture of perceived impacts of proposed restoration activities.

  1. Circadian light-input pathways in Drosophila.

    PubMed

    Yoshii, Taishi; Hermann-Luibl, Christiane; Helfrich-Förster, Charlotte

    2016-01-01

    Light is the most important environmental cue to entrain the circadian clock in most animals. In the fruit fly Drosophila melanogaster, the light entrainment mechanisms of the clock have been well-studied. The Drosophila brain contains approximately 150 neurons that rhythmically express circadian clock genes. These neurons are called "clock neurons" and control behavioral activity rhythms. Many clock neurons express the Cryptochrome (CRY) protein, which is sensitive to UV and blue light, and thus enables clock neurons deep in the brain to directly perceive light. In addition to the CRY protein, external photoreceptors in the Drosophila eyes play an important role in circadian light-input pathways. Recent studies have provided new insights into the mechanisms that integrate these light inputs into the circadian network of the brain. In this review, we will summarize the current knowledge on the light entrainment pathways in the Drosophila circadian clock. PMID:27066180

  2. Ionic currents during sustained pacemaker activity in rabbit sino-atrial myocytes.

    PubMed Central

    Zaza, A; Micheletti, M; Brioschi, A; Rocchetti, M

    1997-01-01

    1. The contribution of various ionic currents to diastolic depolarization (DD) in rabbit sinoatrial myocytes was evaluated by the action potential clamp technique. Individual currents were identified, during sustained pacemaking activity reproduced under voltage clamp conditions, according to their sensitivity to specific channel blockers. 2. The current sensitive to dihydropyridines (DHPs), blockers of L-type Ca2+ current (ICa,L), was small and outward during most of DD. Diastolic DHP-sensitive current was affected by changes in the driving force for K+, but it was insensitive to E-4031, which blocks the current termed IK,r; it was abolished by cell dialysis with a Ca2+ chelator. 3. The current sensitive to 2 mM Cs+ (ICs), a blocker of hyperpolarization-activated current (I(f)), was inward during the whole DD and it was substantially larger than the net inward current flowing during this phase. However, diastolic IK,r, identified in the same cells as the current sensitive to the blocker E-4031, exceeded ICs 2-fold. 4. These findings suggest that: (a) Ca2+ influx during the pacemaker cycle increases a K+ conductance, thus inverting the direction of the net current generated by L-type Ca2+ channel activity during DD; (b) the magnitude of I(f) would be adequate to account fully for DD; however, the coexistence of a larger IK,r suggests that other channels besides I(f) contribute inward current during this phase. PMID:9457645

  3. Habitat management affects soil chemistry and allochthonous organic inputs mediating microbial structure and exo-enzyme activity in Wadden Sea salt-marsh soils

    NASA Astrophysics Data System (ADS)

    Mueller, Peter; Granse, Dirk; Thi Do, Hai; Weingartner, Magdalena; Nolte, Stefanie; Hoth, Stefan; Jensen, Kai

    2016-04-01

    The Wadden Sea (WS) region is Europe's largest wetland and home to approximately 20% of its salt marsh area. Mainland salt marshes of the WS are anthropogenically influenced systems and have traditionally been used for livestock grazing in wide parts. After foundation of WS National Parks in the late 1980s and early 1990s, artificial drainage has been abandoned; however, livestock grazing is still common in many areas of the National Parks and is under ongoing discussion as a habitat-management practice. While studies so far focused on effects of livestock grazing on biodiversity, little is known about how biogeochemical processes, element cycling, and particularly carbon sequestration are affected. Here, we present data from a recent field study focusing on grazing effects on soil properties, microbial exo-enzyme activity, microbial abundance and structure. Exo-enzyme activity was studied conducting digestive enzyme assays for various enzymes involved in C- and N cycling. Microbial abundance and structure was assessed measuring specific gene abundance of fungi and bacteria using quantitative PCR. Soil compaction induced by grazing led to higher bulk density and decreases in soil redox (∆ >100 mV). Soil pH was significantly lower in grazed parts. Further, the proportion of allochthonous organic matter (marine input) was significantly smaller in grazed vs. ungrazed sites, likely caused by a higher sediment trapping capacity of the taller vegetation in the ungrazed sites. Grazing induced changes in bulk density, pH and redox resulted in reduced activity of enzymes involved in microbial C acquisition; however, there was no grazing effect on enzymes involved in N acquisition. While changes in pH, bulk density or redox did not affect microbial abundance and structure, the relative amount of marine organic matter significantly reduced the relative abundance of fungi (F:B ratio). We conclude that livestock grazing directly affects microbial exo-enzyme activity, thus

  4. Photonic Network R&D Activities in Japan-Current Activities and Future Perspectives

    NASA Astrophysics Data System (ADS)

    Kitayama, Ken-Ichi; Miki, Tetsuya; Morioka, Toshio; Tsushima, Hideaki; Koga, Masafumi; Mori, Kazuyuki; Araki, Soichiro; Sato, Ken-Ichi; Onaka, Hiroshi; Namiki, Shu; Aoyama, Tomonori

    2005-10-01

    R&D activities on photonic networks in Japan are presented. First, milestones in current ongoing R&D programs supported by Japanese government agencies are introduced, including long-distance and wavelength division multiplexing (WDM) fiber transmission, wavelength routing, optical burst switching (OBS), and control-plane technology for IP backbone networks. Their goal was set to evolve a legacy telecommunications network to IP-over-WDM networks by introducing technologies for WDM and wavelength routing. We then discuss the perspectives of so-called PHASE II R&D programs for photonic networks over the next 5 years until 2010, by focusing on the report that has been recently issued by the Photonic Internet Forum (PIF), a consortium that has major carriers, telecom vendors, and Japanese academics as members. The PHASE II R&D programs should serve to establish a photonic platform to provide abundant bandwidth on demand, at any time on a real-time basis, through the customer's initiative to promote bandwidth-rich applications, such as grid computing, real-time digital-cinema streaming, medical and educational applications, and network storage in e-commerce.

  5. Principal component analysis of Birkeland currents determined by the Active Magnetosphere and Planetary Electrodynamics Response Experiment

    NASA Astrophysics Data System (ADS)

    Milan, S. E.; Carter, J. A.; Korth, H.; Anderson, B. J.

    2015-12-01

    Principal component analysis is performed on Birkeland or field-aligned current (FAC) measurements from the Active Magnetosphere and Planetary Electrodynamics Response Experiment. Principal component analysis (PCA) identifies the patterns in the FACs that respond coherently to different aspects of geomagnetic activity. The regions 1 and 2 current system is shown to be the most reproducible feature of the currents, followed by cusp currents associated with magnetic tension forces on newly reconnected field lines. The cusp currents are strongly modulated by season, indicating that their strength is regulated by the ionospheric conductance at the foot of the field lines. PCA does not identify a pattern that is clearly characteristic of a substorm current wedge. Rather, a superposed epoch analysis of the currents associated with substorms demonstrates that there is not a single mode of response, but a complicated and subtle mixture of different patterns.

  6. Parent's Interests, Current Involvement and Level of Parental Involvement in School Activities.

    ERIC Educational Resources Information Center

    Gbadamosi, Tara; Lin, Huey-Ling

    This study examined what school activities parents were involved in and the relationship between parents' interests and level of participation. Parents completed self-report questionnaires examining activities they were currently involved in and activities they would like to do in their children's classrooms. Out of 208 surveys distributed, 114…

  7. Miniature and evoked inhibitory junctional currents and gamma-aminobutyric acid-activated current noise in locust muscle fibres.

    PubMed Central

    Cull-Candy, S G

    1986-01-01

    gamma-Aminobutyric acid (GABA) current noise and inhibitory junctional currents (i.j.c.s) have been examined to give properties of the GABA receptor and its associated synaptic channel. Various procedures were used to identify muscle bundles receiving inhibitory innervation. In normal bathing medium the decay time constant of the i.j.c. was tau i.j.c. = 7.6 +/- 0.7 ms (clamp potential, Vm = -80 mV; temperature, T = 21 degrees C). Most muscle fibres were sensitive to ionophoretically applied GABA, irrespective of the presence of inhibitory innervation. GABA current noise obtained at junctional sites gave spectra which were fitted usually with a single Lorentzian component, or occasionally with the sum of two Lorentzians. The conductance of the single inhibitory channel was, gamma (GABA) = 21.6 +/- 0.9 pS (Vm = -80 mV; T = 21 degrees C). The mean 'burst length' of the openings produced by a single receptor activation was tau noise = 4.0 +/- 0.8 ms, at Vm = -80 mV. This decreased exponentially with hyperpolarization. On average tau i.j.c. exceeded tau noise although good agreement was found in some fibres. I.j.c.s were examined in greater detail after excitatory synaptic receptors had been desensitized with 10(-3) M-L-glutamate to abolish all excitatory synaptic activity. Their decay time constant was tau i.j.c. = 7.2 +/- 0.4 ms, and their rise time was 3.3 +/- 0.12 ms, at Vm = -80 mV. An e-fold decrease in tau i.j.c. resulted from a 103 +/- 7.9 mV hyperpolarization; time to peak showed a smaller dependence on Vm. The mean size of the inhibitory quantal event (i.e. response to a single transmitter packet) was estimated from fluctuations in i.j.c. amplitude. Mean quantal content of the i.j.c. was about 30 at normal levels of release. Mean amplitude of the directly measured miniature i.j.c. = 0.65 +/- 0.08 nA at Vm = -80 mV (V eq approximately equal to -40 mV). The amplitude of the quantal event showed a non-linear dependence on Vm. The burst length of the inhibitory

  8. 75 FR 42816 - Agency Information Collection Activities: Notice of Request for Extension of Currently Approved...

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    Federal Register 2010, 2011, 2012, 2013, 2014

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  15. Planar fuel cell utilizing nail current collectors for increased active surface area

    DOEpatents

    George, Thomas J.; Meacham, G. B. Kirby

    2002-03-26

    A plurality of nail current collector members are useful in the gas flow passages of an electrochemical device to optimize the active surfaces of the device and to provide structural support. In addition, the thicknesses of cathode and anode layers within the electrochemical device are varied according to current flow through the device to reduce resistance and increase operating efficiency.

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    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-22

    ... 550 17th Street Building (located on F Street), on business days between 7:00 a.m. and 5:00 p.m. A... CORPORATION Agency Information Collection Activities: Revision of a Currently-Approved Collection; Comment... collection unless it displays a currently valid Office of Management and Budget (OMB) control number. As...

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    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-19

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  18. Oscillatory chloride current evoked by temperature jumps during muscarinic and serotonergic activation in Xenopus oocyte.

    PubMed Central

    Miledi, R; Parker, I; Sumikawa, K

    1987-01-01

    1. Membrane currents were recorded from voltage-clamped oocytes of Xenopus laevis, during temperature jumps imposed by a heating light. Resting oocytes usually showed little response, but large oscillatory membrane currents developed in response to cooling steps applied during activation of 'native' muscarinic receptors. 2. Similar temperature jump (Tjump) currents were seen during activation of oscillatory chloride currents mediated by muscarinic acetylcholine (ACh), serotonin, glutamate and noradrenaline receptors, expressed in the oocyte following injection with messenger ribonucleic acid (mRNA) from rat brain. The Tjump response during muscarinic activation was selectively blocked by atropine, and that during serotonergic activation by methysergide. In contrast, the 'smooth' membrane currents elicited by nicotinic ACh, kainate and gamma-aminobutyric acid (GABA) were not accompanied by Tjump responses. 3. Rapid cooling of the oocyte gave larger Tjump currents than a gradual cooling over a few seconds. The size of the Tjump current elicited by a fixed cooling step increased linearly with the preceding time of warming, becoming maximal at intervals greater than about 100 s. 4. The Tjump current was inward at a clamp potential of -60 mV and reversed direction at about -22 mV, which corresponds to the chloride equilibrium potential in the oocyte. In low-chloride solution the reversal potential was shifted to more positive potentials, but it was almost unchanged by changes in potassium and sodium concentration. The size of the Tjump current decreased as the membrane potential was made more negative than about -40 mV. 5. The period of oscillation of the Tjump current increased with decreasing temperature, following a Q10 of 3.15. Depolarization also caused a small increase in period. 6. The Tjump current was not abolished in calcium-free solution, or by addition of manganese or lanthanum to the bathing solution. However, it was abolished by intracellular injection of

  19. Insulin increases sympathetic nerve activity in part by suppression of tonic inhibitory neuropeptide Y inputs into the paraventricular nucleus in female rats.

    PubMed

    Cassaglia, Priscila A; Shi, Zhigang; Brooks, Virginia L

    2016-07-01

    Following binding to receptors in the arcuate nucleus (ArcN), insulin increases sympathetic nerve activity (SNA) and baroreflex control of SNA via a pathway that includes the paraventricular nucleus of the hypothalamus (PVN). Previous studies in males indicate that the sympathoexcitatory response is mediated by α-melanocyte stimulating hormone (α-MSH), which binds to PVN melanocortin type 3/4 receptors (MC3/4R). The present study was conducted in α-chloralose-anesthetized female rats to test the hypothesis that suppression of inhibitory neuropeptide Y (NPY) inputs to the PVN is also involved. In support of this, blockade of PVN NPY Y1 receptors with BIBO 3304 (NPY1x), ArcN insulin nanoinjections, and PVN NPY1x followed by ArcN insulin each increased lumbar SNA (LSNA) and its baroreflex regulation similarly. Moreover, prior PVN injections of NPY blocked the sympathoexcitatory effects of ArcN insulin. Finally, PVN nanoinjections of the MC3/4R inhibitor SHU9119 prevented both the acute (15 min) and longer, more slowly developing (60 min), increases in LSNA in response to ArcN insulin. In conclusion, in females, ArcN insulin increases LSNA, in part, by suppressing tonic PVN NPY inhibition, which unmasks excitatory α-MSH drive of LSNA. Moreover, the steadily increasing rise in LSNA induced by ArcN insulin is also dependent on PVN MC3/4R. PMID:27122366

  20. Sailing toward Understanding Surface Currents: A Science and Geography Integration Activity for Upper-Elementary Students

    ERIC Educational Resources Information Center

    Eidietis, Laura; Rutherford, Sandra

    2009-01-01

    In the activities presented in this article, students mimic real scientists while constructing predictions and scientific explanations about surface currents. The activities are inspired by and couched within true scientific inquiries regarding the ocean and the North American Great Lakes. Students engage in a classroom inquiry and use map-reading…

  1. Ocean Currents: Marine Science Activities for Grades 5-8. Teacher's Guide.

    ERIC Educational Resources Information Center

    Halversen, Catherine; Beals, Kevin; Strang, Craig

    This teacher's guide attempts to answer questions such as: What causes ocean currents? What impact do they have on Earth's environment? and How have they influenced human history? Seven innovative activities are provided in which students can gain fascinating insights into the earth as the ocean planet. Activities focus on how wind, temperature,…

  2. A Student Activity Fee Primer: Current Research on Collection, Control and Allocation.

    ERIC Educational Resources Information Center

    Meabon, David; And Others

    The past and current status of the student activity fee is reviewed from the perspectives of the legislature, state agency or state board of control, case law, and institutional trends. The analysis is based upon four national studies, a review of case law, and a campus model for the administration of student activity fees. Various states have…

  3. Effect of input noise on neuronal firing rate

    NASA Astrophysics Data System (ADS)

    Gonzalo-Cogno, S.; Samengo, I.

    2013-01-01

    When neurons are driven with a noisy input, the mean and the variance of the stimulus modulate the firing rate. Previous studies have shown that in linear-nonlinear model neurons the mean firing rate obtained in response to a noisy input is the average rate that would be obtained from an ensemble of constant currents. In this work, we study the firing rate of several neuron models, focusing on its dependence on the amount of input noise. We find that for models with monotonic activation curves, the theory provides a good qualitative approximation of the firing rate. For neurons with non-monotonic activation curves, however, the theory fails. The discrepancies between the theory and the simulations appear because rapidly fluctuating stimuli involve intrinsically dynamical processes that cannot be interpreted as an ensemble of constant stimuli.

  4. Talking Speech Input.

    ERIC Educational Resources Information Center

    Berliss-Vincent, Jane; Whitford, Gigi

    2002-01-01

    This article presents both the factors involved in successful speech input use and the potential barriers that may suggest that other access technologies could be more appropriate for a given individual. Speech input options that are available are reviewed and strategies for optimizing use of speech recognition technology are discussed. (Contains…

  5. MDS MIC Catalog Inputs

    NASA Technical Reports Server (NTRS)

    Johnson-Throop, Kathy A.; Vowell, C. W.; Smith, Byron; Darcy, Jeannette

    2006-01-01

    This viewgraph presentation reviews the inputs to the MDS Medical Information Communique (MIC) catalog. The purpose of the group is to provide input for updating the MDS MIC Catalog and to request that MMOP assign Action Item to other working groups and FSs to support the MITWG Process for developing MIC-DDs.

  6. High input impedance amplifier

    NASA Technical Reports Server (NTRS)

    Kleinberg, Leonard L.

    1995-01-01

    High input impedance amplifiers are provided which reduce the input impedance solely to a capacitive reactance, or, in a somewhat more complex design, provide an extremely high essentially infinite, capacitive reactance. In one embodiment, where the input impedance is reduced in essence, to solely a capacitive reactance, an operational amplifier in a follower configuration is driven at its non-inverting input and a resistor with a predetermined magnitude is connected between the inverting and non-inverting inputs. A second embodiment eliminates the capacitance from the input by adding a second stage to the first embodiment. The second stage is a second operational amplifier in a non-inverting gain-stage configuration where the output of the first follower stage drives the non-inverting input of the second stage and the output of the second stage is fed back to the non-inverting input of the first stage through a capacitor of a predetermined magnitude. These amplifiers, while generally useful, are very useful as sensor buffer amplifiers that may eliminate significant sources of error.

  7. Early and current physical activity: relationship with intima-media thickness and metabolic variables in adulthood.

    PubMed

    Lima, Manoel C S; Barbosa, Maurício F; Diniz, Tiego A; Codogno, Jamile S; Freitas Júnior, Ismael F; Fernandes, Rômulo A

    2014-08-29

    Background: It is unclear whether early physical activity has a greater influence on intima-media thickness and metabolic variables than current physical activity. Objective: To analyze the relationship between current and early physical activity, metabolic variables, and intima-media thickness measures in adults. Method: The sample was composed of 55 healthy subjects of both sexes (33 men and 22 women). Total body fat and trunk fat were estimated by dual-energy X-ray absorptiometry. Carotid and femoral intima-media thickness were measured using a Doppler ultrasound device. A 12-hour fasting blood sample collection was taken (fasting glucose and lipid profile). Early physical activity was assessed through face-to-face interview, and the current physical activity was assessed by pedometer (Digi-Walker Yamax, SW200), which was used for a period of seven days. Results: Current physical activity was negatively related to total cholesterol (rho=-0.31), while early physical activity was negatively related to triglycerides (rho=-0.42), total cholesterol (rho=-0.28), very low density lipoprotein (rho=-0.44), and carotid intima-media thickness (rho=-0.50). In the multivariate model, subjects engaged in sports activities during early life had lower values of very low density lipoprotein (b=-8.74 [b=-16.1; -1.47]) and carotid intima-media thickness (b=-0.17 [95%CI: -0.28; -0.05]). Conclusion: Early 95%CI physical activity has a significant influence on carotid intima-media thickness, regardless of the current physical activity. PMID:25185030

  8. Early and current physical activity: relationship with intima-media thickness and metabolic variables in adulthood

    PubMed Central

    Lima, Manoel C. S.; Barbosa, Maurício F.; Diniz, Tiego A.; Codogno, Jamile S.; Freitas, Ismael F.; Fernandes, Rômulo A.

    2014-01-01

    Background: It is unclear whether early physical activity has a greater influence on intima-media thickness and metabolic variables than current physical activity. Objective: To analyze the relationship between current and early physical activity, metabolic variables, and intima-media thickness measures in adults. Method: The sample was composed of 55 healthy subjects of both sexes (33 men and 22 women). Total body fat and trunk fat were estimated by dual-energy X-ray absorptiometry. Carotid and femoral intima-media thickness were measured using a Doppler ultrasound device. A 12-hour fasting blood sample collection was taken (fasting glucose and lipid profile). Early physical activity was assessed through face-to-face interview, and the current physical activity was assessed by pedometer (Digi-Walker Yamax, SW200), which was used for a period of seven days. Results: Current physical activity was negatively related to total cholesterol (rho=-0.31), while early physical activity was negatively related to triglycerides (rho=-0.42), total cholesterol (rho=-0.28), very low density lipoprotein (rho=-0.44), and carotid intima-media thickness (rho=-0.50). In the multivariate model, subjects engaged in sports activities during early life had lower values of very low density lipoprotein (b=-8.74 [b=-16.1; -1.47]) and carotid intima-media thickness (b=-0.17 [95%CI: -0.28; -0.05]). Conclusion: Early 95%CI physical activity has a significant influence on carotid intima-media thickness, regardless of the current physical activity. PMID:25372009

  9. EVOLUTION OF CURRENTS OF OPPOSITE SIGNS IN THE FLARE-PRODUCTIVE SOLAR ACTIVE REGION NOAA 10930

    SciTech Connect

    Ravindra, B.; Venkatakrishnan, P.; Tiwari, Sanjiv Kumar; Bhattacharyya, R. E-mail: pvk@prl.res.in E-mail: ramit@prl.res.in

    2011-10-10

    Analysis of a time series of high spatial resolution vector magnetograms of the active region NOAA 10930 available from the Solar Optical Telescope SpectroPolarimeter on board Hinode revealed that there is a mixture of upward and downward currents in the two footpoints of an emerging flux rope. The flux emergence rate is almost the same in both the polarities. We observe that along with an increase in magnetic flux, the net current in each polarity increases initially for about three days after which it decreases. This net current is characterized by having exactly opposite signs in each polarity while its magnitude remains almost the same most of the time. The decrease of the net current in both the polarities is due to the increase of current having a sign opposite to that of the net current. The dominant current, with the same sign as the net current, is seen to increase first and then decreases during the major X-class flares. Evolution of non-dominant current appears to be a necessary condition for flare initiation. The above observations can be plausibly explained in terms of the superposition of two different force-free states resulting in a non-zero Lorentz force in the corona. This Lorentz force then pushes the coronal plasma and might facilitate the magnetic reconnection required for flares. Also, the evolution of the net current is found to follow the evolution of magnetic shear at the polarity inversion line.

  10. A methodology for fast assessments to the electrical activity of barrel fields in vivo: from population inputs to single unit outputs

    PubMed Central

    Riera, Jorge J.; Goto, Takakuni; Kawashima, Ryuta

    2014-01-01

    Here we propose a methodology to analyze volumetric electrical activity of neuronal masses in the somatosensory barrel field of Wistar rats. The key elements of the proposed methodology are a three-dimensional microelectrode array, which was customized by our group to observe extracellular recordings from an extended area of the barrel field, and a novel method for the current source density analysis. By means of this methodology, we were able to localize single barrels from their event-related responses to single whisker deflection. It was also possible to assess the spatiotemporal dynamics of neuronal aggregates in several barrels at the same time with the resolution of single neurons. We used simulations to study the robustness of our methodology to unavoidable physiological noise and electrode configuration. We compared the accuracy to reconstruct neocortical current sources with that obtained with a previous method. This constitutes a type of electrophysiological microscopy with high spatial and temporal resolution, which could change the way we analyze the activity of cortical neurons in the future. PMID:24550785

  11. Paralleling power MOSFETs in their active region: Extended range of passively forced current sharing

    NASA Technical Reports Server (NTRS)

    Niedra, Janis M.

    1989-01-01

    A simple passive circuit that improves current balance in parallelled power MOSFETs that are not precisely matched and that are operated in their active region from a common gate drive are exhibited. A nonlinear circuit consisting of diodes and resistors generates the differential gate potential required to correct for unbalance while maintaining low losses over a range of current. Also application of a thin tape wound magnetic core to effect dynamic current balance is reviewed, and a simple theory is presented showing that for operation in the active region the branch currents tend to revert to their normal unbalanced values even if the core is not driven into saturation. Results of several comparative experiments are given.

  12. Correlation of Solar Activities with the Telluric Currents Level in the Northern Region of Malaysia

    NASA Astrophysics Data System (ADS)

    Razelan, Mazlina M.; Said, N. Masdiana Md; Aziz, A. H. A.; Chong, H. Y.; Nawawi, M.

    2010-07-01

    The relation between solar activities and the geomagnetic field induced currents (GIC) have been well studied in the auroral region and it usually occurs most frequently at high latitudes. However, during major geomagnetic storms, the auroral zone can extend substantially towards lower latitudes. Disturbance caused by solar activities can disrupt power grids and also increase the corrosion rate of buried natural gas pipelines. GIC are driven by the geomagnetic field induced by a geomagnetic disturbance. In this paper, we investigated the correlation between solar activities using the interplanetary magnetic field (IMF) and geomagnetic disturbance storm time (DST) index data with the telluric currents (also referred to as geomagnetic induced currents GIC) level through the disturbance pattern of geomagnetic field. The research areas are from Lunas in Kedah to Perlis. The pattern of geomagnetic field disturbance had been identified and analyzed to investigate the harmful effect of geomagnetic storms towards the performance of complex power grid in Malaysia.

  13. A Palladium-Binding Deltarhodopsin for Light-Activated Conversion of Protonic to Electronic Currents.

    PubMed

    Soto-Rodríguez, Jessica; Hemmatian, Zahra; Josberger, Erik E; Rolandi, Marco; Baneyx, François

    2016-08-01

    Fusion of a palladium-binding peptide to an archaeal rhodopsin promotes intimate integration of the lipid-embedded membrane protein with a palladium hydride protonic contact. Devices fabricated with the palladium-binding deltarhodopsin enable light-activated conversion of protonic currents to electronic currents with on/off responses complete in seconds and a nearly tenfold increase in electrical signal relative to those made with the wild-type protein. PMID:27185384

  14. Characterization of the hyperpolarization-activated chloride current in dissociated rat sympathetic neurons.

    PubMed

    Clark, S; Jordt, S E; Jentsch, T J; Mathie, A

    1998-02-01

    1. Dissociated rat superior cervical ganglion (SCG) neurons have been shown to possess a hyperpolarization-activated inwardly rectifying chloride current. The current was not altered by changes in external potassium concentration, replacing external cations with NMDG (N-methyl-D-glucamine) or by addition of 10 mM caesium or barium ions. 2. The reversal potential of the current was altered by changing external anions. The anion selectivity of the current was Cl- > Br- > I- > cyclamate. All substituted permeant anions also blocked the current. 3. The current was blocked by DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid), 9AC (anthracene-9-carboxylic acid) and NPPB (5-nitro-2-(3-phenylpropylamino)benzoic acid) but was unaffected by SITS (4-acetamido-4'-isothiocyanatostilbene- 2,2'-disulphonic acid) and niflumic acid. The effective blockers were voltage dependent; DIDS and NPPB were more effective at depolarized potentials while 9AC was more effective at hyperpolarized potentials. 4. The current was enhanced by extracellular acidification and reduced by extracellular alkalinization. Reducing external osmolarity was without effect in conventional whole-cell recording but enhanced current amplitude in those perforated-patch recordings where little current was evident in control external solution. 5. The current in SCG neurons was blocked by external cadmium and zinc. ClC-2 chloride currents expressed in Xenopus oocytes were also sensitive to block by these divalent ions and by DIDS but the sensitivity of ClC-2 to block by cadmium ions was lower than that of the current in SCG neurons. 6. Reverse transcriptase-polymerase chain reaction (RT-PCR) experiments showed the presence of mRNA for ClC-2 in SCG neurons but not in rat cerebellar granule cells which do not possess a hyperpolarization-activated Cl- current. 7. The data suggest that ClC-2 may be functionally expressed in rat SCG neurons. This current may play a role in regulating the internal chloride

  15. Patch-clamp analysis of voltage-activated and chemically activated currents in the vomeronasal organ of Sternotherus odoratus (stinkpot/musk turtle)

    PubMed Central

    Fadool, D. A.; Wachowiak, M.; Brann, J. H.

    2011-01-01

    Summary The electrophysiological basis of chemical communication in the specialized olfactory division of the vomeronasal (VN) organ is poorly understood. In total, 198 patch-clamp recordings were made from 42 animals (Sternotherus odoratus, the stinkpot/musk turtle) to study the electrically and chemically activated properties of VN neurons. The introduction of tetramethylrhodamine-conjugated dextran into the VN orifice permitted good visualization of the vomeronasal neural epithelium prior to dissociating it into single neurons. Basic electrical properties of the neurons were measured (resting potential, −54.5±2.7 mV, N=11; input resistance, 6.7±1.4GΩ, N=25; capacitance, 4.2±0.3 pF, N=22; means ± S.E.M.). The voltage-gated K+ current inactivation rate was significantly slower in VN neurons from males than in those from females, and K+ currents in males were less sensitive (greater Ki) to tetraethylammonium. Vomeronasal neurons were held at a holding potential of −60 mV and tested for their response to five natural chemicals, female urine, male urine, female musk, male musk and catfish extract. Of the 90 VN neurons tested, 33 (34 %) responded to at least one of the five compounds. The peak amplitude of chemically evoked currents ranged from 4 to 180 pA, with two-thirds of responses less than 25 pA. Urine-evoked currents were of either polarity, whereas musk and catfish extract always elicited only inward currents. Urine applied to neurons harvested from female animals evoked currents that were 2–3 times larger than those elicited from male neurons. Musk-evoked inward currents were three times the magnitude of urine-or catfish-extract-evoked inward currents. The calculated breadth of responsiveness for neurons presented with this array of five chemicals indicated that the mean response spectrum of the VN neurons is narrow (H metric 0.11). This patch-clamp study indicates that VN neurons exhibit sexual dimorphism in function and specificity in response

  16. Format( )MEDIC( )Input

    NASA Astrophysics Data System (ADS)

    Foster, K.

    1994-09-01

    This document is a description of a computer program called Format( )MEDIC( )Input. The purpose of this program is to allow the user to quickly reformat wind velocity data in the Model Evaluation Database (MEDb) into a reasonable 'first cut' set of MEDIC input files (MEDIC.nml, StnLoc.Met, and Observ.Met). The user is cautioned that these resulting input files must be reviewed for correctness and completeness. This program will not format MEDb data into a Problem Station Library or Problem Metdata File. A description of how the program reformats the data is provided, along with a description of the required and optional user input and a description of the resulting output files. A description of the MEDb is not provided here but can be found in the RAS Division Model Evaluation Database Description document.

  17. Regional Hospital Input Price Indexes

    PubMed Central

    Freeland, Mark S.; Schendler, Carol Ellen; Anderson, Gerard

    1981-01-01

    This paper describes the development of regional hospital input price indexes that is consistent with the general methodology used for the National Hospital Input Price Index. The feasibility of developing regional indexes was investigated because individuals inquired whether different regions experienced different rates of increase in hospital input prices. The regional indexes incorporate variations in cost-share weights (the amount an expense category contributes to total spending) associated with hospital type and location, and variations in the rate of input price increases for various regions. We found that between 1972 and 1979 none of the regional price indexes increased at average annual rates significantly different from the national rate. For the more recent period 1977 through 1979, the increase in one Census Region was significantly below the national rate. Further analyses indicated that variations in cost-share weights for various types of hospitals produced no substantial variations in the regional price indexes relative to the national index. We consider these findings preliminary because of limitations in the availability of current, relevant, and reliable data, especially for local area wage rate increases. PMID:10309557

  18. Current-induced strength degradation of activated carbon spheres in carbon supercapacitors

    NASA Astrophysics Data System (ADS)

    Sun, Yuan; Chen, Rong; Lipka, Stephen M.; Yang, Fuqian

    2016-05-01

    Activated carbon microspheres (ACSs), which are prepared using hydrothermal synthesis and ammonia activation, are used as the active materials in the anode and cathode of electric double layer capacitors (EDLCs). The ACS-based EDLCs of symmetrical electrodes exhibit good stability and a high degree of reversibility over 2000 charge-discharge cycles for electric current up to 10 A g‑1. The ACSs maintain a nongraphitized carbon structure after over 2000 charge-discharge cycles. Nanoindentation experiments are performed on the ACSs, which are electrochemically cycled in a voltage window of 0–1 V at three electric currents of 0.5, 5, and 10 A g‑1. For the same indentation load, both the contact modulus and indentation hardness of the ACSs decrease with the increase of the electric current used in the electrical charging and discharging. These results suggest that there exists strength degradation introduced by the electric current. A larger electric current will cause more strength degradation than a smaller electric current.

  19. CURRENT HELICITY OF ACTIVE REGIONS AS A TRACER OF LARGE-SCALE SOLAR MAGNETIC HELICITY

    SciTech Connect

    Zhang, H.; Gao, Y.; Xu, H.; Moss, D.; Kleeorin, N.; Rogachevskii, I.; Kuzanyan, K.; Sokoloff, D.

    2012-05-20

    We demonstrate that the current helicity observed in solar active regions traces the magnetic helicity of the large-scale dynamo generated field. We use an advanced two-dimensional mean-field dynamo model with dynamo saturation based on the evolution of the magnetic helicity and algebraic quenching. For comparison, we also studied a more basic two-dimensional mean-field dynamo model with simple algebraic alpha-quenching only. Using these numerical models we obtained butterfly diagrams both for the small-scale current helicity and also for the large-scale magnetic helicity, and compared them with the butterfly diagram for the current helicity in active regions obtained from observations. This comparison shows that the current helicity of active regions, as estimated by -A {center_dot} B evaluated at the depth from which the active region arises, resembles the observational data much better than the small-scale current helicity calculated directly from the helicity evolution equation. Here B and A are, respectively, the dynamo generated mean magnetic field and its vector potential. A theoretical interpretation of these results is given.

  20. Soil Moisture Active Passive (SMAP) Calibration and validation plan and current activities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The primary objective of the SMAP calibration and validation (Cal/Val) program is demonstrating that the science requirements (product accuracy and bias) have been met over the mission life. This begins during pre-launch with activities that contribute to high quality products and establishing post-...

  1. Adaptive Fuzzy Hysteresis Band Current Controller for Four-Wire Shunt Active Filter

    NASA Astrophysics Data System (ADS)

    Hamoudi, F.; Chaghi, A.; Amimeur, H.; Merabet, E.

    2008-06-01

    This paper presents an adaptive fuzzy hysteresis band current controller for four-wire shunt active power filters to eliminate harmonics and to compensate reactive power in distribution systems in order to keep currents at the point of common coupling sinusoidal and in phase with the corresponding voltage and the cancel neutral current. The conventional hysteresis band known for its robustness and its advantage in current controlled applications is adapted with a fuzzy logic controller to change the bandwidth according to the operating point in order to keep the frequency modulation at tolerable limits. The algorithm used to identify the reference currents is based on the synchronous reference frame theory (dqγ). Finally, simulation results using Matlab/Simulink are given to validate the proposed control.

  2. Calcium-activated chloride currents in olfactory sensory neurons from mice lacking bestrophin-2

    PubMed Central

    Pifferi, Simone; Dibattista, Michele; Sagheddu, Claudia; Boccaccio, Anna; Al Qteishat, Ahmed; Ghirardi, Filippo; Tirindelli, Roberto; Menini, Anna

    2009-01-01

    Olfactory sensory neurons use a chloride-based signal amplification mechanism to detect odorants. The binding of odorants to receptors in the cilia of olfactory sensory neurons activates a transduction cascade that involves the opening of cyclic nucleotide-gated channels and the entry of Ca2+ into the cilia. Ca2+ activates a Cl− current that produces an efflux of Cl− ions and amplifies the depolarization. The molecular identity of Ca2+-activated Cl− channels is still elusive, although some bestrophins have been shown to function as Ca2+-activated Cl− channels when expressed in heterologous systems. In the olfactory epithelium, bestrophin-2 (Best2) has been indicated as a candidate for being a molecular component of the olfactory Ca2+-activated Cl− channel. In this study, we have analysed mice lacking Best2. We compared the electrophysiological responses of the olfactory epithelium to odorant stimulation, as well as the properties of Ca2+-activated Cl− currents in wild-type (WT) and knockout (KO) mice for Best2. Our results confirm that Best2 is expressed in the cilia of olfactory sensory neurons, while odorant responses and Ca2+-activated Cl− currents were not significantly different between WT and KO mice. Thus, Best2 does not appear to be the main molecular component of the olfactory channel. Further studies are required to determine the function of Best2 in the cilia of olfactory sensory neurons. PMID:19622610

  3. Current and Future Research in Active Control of Lightweight, Flexible Structures Using the X-56 Aircraft

    NASA Technical Reports Server (NTRS)

    Ryan, John J.; Bosworth, John T.; Burken, John J.; Suh, Peter M.

    2014-01-01

    The X-56 Multi-Utility Technology Testbed aircraft system is a versatile experimental research flight platform. The system was primarily designed to investigate active control of lightweight flexible structures, but is reconfigurable and capable of hosting a wide breadth of research. Current research includes flight experimentation of a Lockheed Martin designed active control flutter suppression system. Future research plans continue experimentation with alternative control systems, explore the use of novel sensor systems, and experiments with the use of novel control effectors. This paper describes the aircraft system, current research efforts designed around the system, and future planned research efforts that will be hosted on the aircraft system.

  4. Current Research Activities in Drive System Technology in Support of the NASA Rotorcraft Program

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F.; Zakrajsek, James J.

    2006-01-01

    Drive system technology is a key area for improving rotorcraft performance, noise/vibration reduction, and reducing operational and manufacturing costs. An overview of current research areas that support the NASA Rotorcraft Program will be provided. Work in drive system technology is mainly focused within three research areas: advanced components, thermal behavior/emergency lubrication system operation, and diagnostics/prognostics (also known as Health and Usage Monitoring Systems (HUMS)). Current research activities in each of these activities will be presented. Also, an overview of the conceptual drive system requirements and possible arrangements for the Heavy Lift Rotorcraft program will be reviewed.

  5. Input- and output-oriented approaches to implementing ecosystem management

    NASA Astrophysics Data System (ADS)

    Montgomery, David R.

    1995-03-01

    Input- and output-oriented approaches to landscape management have distinct roles for resource protection, environmental restoration, and sustainable land management. Implementing recent proposals for ecosystem management in the western United States involves a synthesis of input and output management. Within the broader context of ecosystem management, input management focuses on tailoring land use to the landscape, whereas output management employs assessments of resource condition to trigger modified management activity once resources are degraded to specified threshold conditions. Current approaches to landscape-scale management, however, tend to rely primarily on output-oriented strategies that are most effective for monitoring environmental conditions. Current uses of input management focus on environmental impact assessments, which generally are site- or project-specific analyses. The compeexity and dynamic nature of ecosystems, and the range of scales over which ecological processes operate, imply that development and incorporation of input-oriented approaches into landscape-scale management is necessary to implement ecosystem management as a strategy for sustainable land use.

  6. Reduction, analysis, and properties of electric current systems in solar active regions

    NASA Technical Reports Server (NTRS)

    Gary, G. Allen; Demoulin, Pascal

    1995-01-01

    The specific attraction and, in large part, the significance of solar magnetograms lie in the fact that they give the most important data on the electric currents and the nonpotentiality of active regions. Using the vector magnetograms from the Marshall Space Flight Center (MSFC), we employ a unique technique in the area of data analysis for resolving the 180 deg ambiguity in order to calculate the spatial structure of the vertical electric current density. The 180 deg ambiguity is resolved by applying concepts from the nonlinear multivariable optimization theory. The technique is shown to be of particular importance in very nonpotential active regions. The characterization of the vertical electric current density for a set of vector magnetograms using this method then gives the spatial scale, locations, and magnitude of these current systems. The method, which employs an intermediate parametric function which covers the magnetogram and which defines the local `preferred' direction, minimizes a specific functional of the observed transverse magnetic field. The specific functional that is successful is the integral of the square of the vertical current density. We find that the vertical electric current densities have common characteristics for the extended bipolar (beta) (gamma) (delta)-regions studied. The largest current systems have j(sub z)'s which maximizes around 30 mA/sq m and have a linear decreasing distribution to a diameter of 30 Mn.

  7. Reduction, Analysis, and Properties of Electric Current Systems in Solar Active Regions

    NASA Technical Reports Server (NTRS)

    Gary, G. Allen; Demoulin, Pascal

    1995-01-01

    The specific attraction and, in large part, the significance of solar vector magnetograms lie in the fact that they give the most important data on the electric currents and the nonpotentiality of active regions. Using the vector magnetograms from the Marshall Space Flight Center (MSFC), we employ a unique technique in the area of data analysis for resolving the 180 degree ambiguity in order to calculate the spatial structure of the vertical electric current density. The 180 degree ambiguity is resolved by applying concepts from the nonlinear multivariable optimization theory. The technique is shown to be of particular importance in very nonpotential active regions. The characterization of the vertical electric current density for a set of vector magnetograms using this method then gives the spatial scale, locations, and magnitude of these current systems. The method, which employs an intermediate parametric function which covers the magnetogram and which defines the local "preferred" direction, minimizes a specific functional of the observed transverse magnetic field. The specific functional that is successful is the integral of the square of the vertical current density. We find that the vertical electric current densities have common characteristics for the extended bipolar beta gamma delta-regions studied. The largest current systems have j(sub z)'s which maximizes around 30 mA per square meter and have a linear decreasing distribution to a diameter of 30 Mm.

  8. Photographic evidence of variable bottom-current activity in the Suruga and Sagami Bays, central Japan

    NASA Astrophysics Data System (ADS)

    Okada, Hakuyu; Ohta, Suguru

    1993-01-01

    Complex patterns of bottom-current behaviour were clarified by studies of sedimentary features and orientations of benthic animals in the deep Suruga and Sagami Bays on the Pacific side of central Honshu, Japan. Both the Suruga and Sagami Bay measure about 60 km in length as well as in width at their mouths and are about 1500 m deep in their central portions. The size of each bay is comparable to that of ancient forearc basins. The bottom sediments are characterized by turbidites and slump deposits. At 32 stations on the bottom of the bays, deep-sea photographs were taken, most of which clearly indicate bottom-current activity. Current-induced bottom features are current-lineations, moat-like scours around resistant objects, crag-and-tail structures behind obstacles, ripple marks, sand ridges and deformed biogenic structures such as burrows, mounds, tracks and faeces. These features are produced by bottom currents with rather high velocities. Other important current indicators are some benthic organisms, which in general show a sensitive response to currents and adopt particular orientations. Typical examples of megabenthos identified in the bottom photographs as effective current indicators are the small deimatid holothurian Peniagone japonica, the benthic shrimp Glyphocrangon hastacauda, sea anemones, and sea pens. Among them, the orientation of Peniagone japonica shows abrupt changes of current direction with time, for example, from N (0°) to SW (240°) during 15 min and from N to S and back to N, a complete rotation during 40 min. The results of these observations indicate that the bottom currents in deep bays tend to fluctuate rapidly in velocity and direction, probably owing to strong internal tidal waves in the very steep embayments. Upslope currents appear to be present at the mouths of submarine canyons. Thus, it should be borne in mind that palaeocurrent analysis of ancient bottom-current deposits or contourites is limited in application.

  9. Field-Aligned Current Sheet Motion and Its Correlation with Solar Wind Conditions and Geomagnetic Activities

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Le, G.; Boardsen, S. A.; Slavin, J. A.; Strangeway, R. J.

    2008-05-01

    Field-aligned currents (FACs) are the currents flowing into and out of the ionosphere which connect to the magnetosphere. They provide an essential linkage between the solar wind - magnetosphere system and the ionosphere, and the understanding of these currents is important for global magnetosphere dynamics and space weather prediction. The three spacecraft ST-5 constellation provides an unprecedented opportunity to study in situ FAC dynamics in time scales (10 sec to 10 min) that can not be achieved previously with single spacecraft studies or large-spaced conjugate spacecraft studies. In this study, we use the magnetic field observations during the whole ST-5 mission and their corresponding solar wind conditions to study the dependence of FAC current sheet motion and intensity on solar wind conditions. FAC peak current densities show very good correlations with some solar wind parameters, including IMF Bz, dynamic pressure, Ey, and some IMF angles, but not with other parameters. Instant FAC speeds show generally much weaker dependence on solar wind conditions comparing to FAC peak current densities. This obvious uncorrelation between FAC peak current densities and speeds implies that FAC peak current densities are more consistently controlled by solar wind conditions and geomagnetic activities, while FAC speeds are more oscillatory, sometimes with higher speeds during quieter times and lower speeds during more turbulent times.

  10. The morphology of flare phenomena, magnetic fields, and electric currents in active regions. III - NOAA active region 6233 (1990 August)

    NASA Technical Reports Server (NTRS)

    De La Beaujardiere, J.-F.; Canfield, Richard C.; Leka, K. D.

    1993-01-01

    We investigate the spatial relationship between vertical electric currents and flare phenomena in NOAA Active Region 6233, which was observed 1990, August 28-31 at Mees Solar Observatory. The two flares studied are the 1N/M1.8 flare on August 28, 22:30 UT and the 1N/M1.6 flare on August 29, 20:35 UT. Using Stokes polarimetry we make magnetograms of the region and compute the vertical current density. Using H-alpha imaging spectroscopy we identify sites of intense nonthermal electron precipitation or of high coronal pressure. The precipitation in these flares is barely strong enough to be detectable. We find that both precipitation and high pressure tend to occur near vertical currents, but that neither phenomenon is cospatial with current maxima. In contrast with the conclusion of other authors, we argue that these observations do not support a current-interruption model for flares, unless the relevant currents are primarily horizontal. The magnetic morphology and temporal evolution of these flares suggest that an erupting filament model may be relevant, but this model does not explicitly predict the relationship between precipitation, high pressure, and vertical currents.

  11. Activation state of the hyperpolarization-activated current modulates temperature-sensitivity of firing in locus coeruleus neurons from bullfrogs.

    PubMed

    Santin, Joseph M; Hartzler, Lynn K

    2015-06-15

    Locus coeruleus neurons of anuran amphibians contribute to breathing control and have spontaneous firing frequencies that, paradoxically, increase with cooling. We previously showed that cooling inhibits a depolarizing membrane current, the hyperpolarization-activated current (I h) in locus coeruleus neurons from bullfrogs, Lithobates catesbeianus (Santin JM, Watters KC, Putnam RW, Hartzler LK. Am J Physiol Regul Integr Comp Physiol 305: R1451-R1464, 2013). This suggests an unlikely role for I h in generating cold activation, but led us to hypothesize that inhibition of I h by cooling functions as a physiological brake to limit the cold-activated response. Using whole cell electrophysiology in brain slices, we employed 2 mM Cs(+) (an I h antagonist) to isolate the role of I h in spontaneous firing and cold activation in neurons recorded with either control or I h agonist (cyclic AMP)-containing artificial intracellular fluid. I h did not contribute to the membrane potential (V m) and spontaneous firing at 20°C. Although voltage-clamp analysis confirmed that cooling inhibits I h, its lack of involvement in setting baseline firing and V m precluded its ability to regulate cold activation as hypothesized. In contrast, neurons dialyzed with cAMP exhibited greater baseline firing frequencies at 20°C due to I h activation. Our hypothesis was supported when the starting level of I h was enhanced by elevating cAMP because cold activation was converted to more ordinary cold inhibition. These findings indicate that situations leading to enhancement of I h facilitate firing at 20°C, yet the hyperpolarization associated with inhibiting a depolarizing cation current by cooling blunts the net V m response to cooling to oppose normal cold-depolarizing factors. This suggests that the influence of I h activation state on neuronal firing varies in the poikilothermic neuronal environment. PMID:25833936

  12. NSAIDs modulate GABA-activated currents via Ca2+-activated Cl− channels in rat dorsal root ganglion neurons

    PubMed Central

    ZHAO, LEI; LI, LI; MA, KE-TAO; WANG, YANG; LI, JING; SHI, WEN-YAN; ZHU, HE; ZHANG, ZHONG-SHUANG; SI, JUN-QIANG

    2016-01-01

    The ability of non-steroidal anti-inflammatory drugs (NSAIDs) to modulate γ-aminobutyrate (GABA)-activated currents via Ca2+-activated Cl− channels in rat dorsal root ganglion neurons (DRG), was examined in the present study. During the preparation of DRG neurons harvested from Sprague-Dawley rats, the whole-cell recording technique was used to record the effect of NSAIDs on GABA-activated inward currents, and the expression levels of the TMEM16A and TMEM16B subunits were revealed. In the event that DRG neurons were pre-incubated for 20 sec with niflumic acid (NFA) and 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) prior to the administration of GABA, the GABA-induced inward currents were diminished markedly in the majority of neurons examined (96.3%). The inward currents induced by 100 µmol/l GABA were attenuated by (0±0.09%; neurons = 4), (5.32±3.51%; neurons = 6), (21.3±4.00%; neurons = 5), (33.8±5.20%; neurons = 17), (52.2±5.10%; neurons = 4) and (61.1±4.12%; neurons = 12) by 0.1, 1, 3, 10, 30 and 100 µmol/l NFA, respectively. The inward currents induced by 100 µmol/l GABA were attenuated by (13.8±6%; neurons = 6), (23.2±14.7%; neurons = 6) and (29.7±9.1%; neurons = 9) by 3, 10 and 30 µmol/l NPPB, respectively. NFA and NPPB dose-dependently inhibited GABA-activated currents with half maximal inhibitory concentration (IC50) values of 6.7 and 11 µmol/l, respectively. The inhibitory effect of 100 µmol/l NFA on the GABA-evoked inward current were also strongly inhibited by nitrendipine (NTDP; an L-type calcium channel blocker), 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid tetrakis (a highly selective calcium chelating reagent), caffeine (a widely available Ca2+ consuming drug) and calcium-free extracellular fluid, in a concentration-dependent manner. Immunofluorescent staining indicated that TMEM16A and TMEM16B expression was widely distributed in DRG neurons. The results suggest that NSAIDs may be able to regulate Ca2

  13. Soil Moisture Active Passive (SMAP) Calibration and Validation Plan and Current Activities

    NASA Technical Reports Server (NTRS)

    Jackson, T. J.; Cosh, M.; Bindlish, R.; Crow, W.; Colliander, A.; Njoku, E.; McDonald, K.; Kimball, J.; Belair, S.; Walker, J.; Entekhabi, P.; O'Neill, P.

    2010-01-01

    The primary objective of the SMAP calibration and validation (Cal/Val) program is demonstrating that the science requirements (product accuracy and bias) have been met over the mission life. This begins during pre-launch with activities that contribute to high quality products and establishing post-launch validation infrastructure and continues through the mission life. However, the major focus is on a relatively short Cal/Val period following launch. The general approach and elements of the SMAP Cal/Val plan will be described and along with details on several ongoing or recent field experiments designed to address both near- and long-term Cal/Val.

  14. 77 FR 21104 - Agency Information Collection Activities: Form I-694, Extension of a Currently Approved...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-09

    ... a brief abstract: Primary: Individuals and households. USCIS uses the information provided on Form I... SECURITY U.S. Citizenship and Immigration Services Agency Information Collection Activities: Form I-694, Extension of a Currently Approved Information Collection; Comment Request ACTION: 60-Day Notice...

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  1. 77 FR 23734 - Agency Information Collection Activities: Form I-361, Extension of a Currently Approved...

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  11. Video: Animals; Electric Current; Force; Science Activities. Learning in Science Project. Working Papers 51-54.

    ERIC Educational Resources Information Center

    Bell, Beverley; And Others

    Four papers to be used in conjunction with video-tapes developed by the Learning in Science Project are presented. Topic areas of the papers focus on: (1) animals; (2) electric current; (3) force; and (4) science activities. The first paper presents transcripts of class discussions focusing on the scientific meaning of the word animal. The second…

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  16. Summary of Current and Future MSFC International Space Station Environmental Control and Life Support System Activities

    NASA Technical Reports Server (NTRS)

    Ray, Charles D.; Carrasquillo, Robyn L.; Minton-Summers, Silvia

    1997-01-01

    This paper provides a summary of current work accomplished under technical task agreement (TTA) by the Marshall Space Flight Center (MSFC) regarding the Environmental Control and Life Support System (ECLSS) as well as future planning activities in support of the International Space Station (ISS). Current activities include ECLSS computer model development, component design and development, subsystem integrated system testing, life testing, and government furnished equipment delivered to the ISS program. A long range plan for the MSFC ECLSS test facility is described whereby the current facility would be upgraded to support integrated station ECLSS operations. ECLSS technology development efforts proposed to be performed under the Advanced Engineering Technology Development (AETD) program are also discussed.

  17. Sodium currents activate without a Hodgkin-and-Huxley-type delay in central mammalian neurons.

    PubMed

    Baranauskas, Gytis; Martina, Marco

    2006-01-11

    Hodgkin and Huxley established that sodium currents in the squid giant axons activate after a delay, which is explained by the model of a channel with three identical independent gates that all have to open before the channel can pass current (the HH model). It is assumed that this model can adequately describe the sodium current activation time course in all mammalian central neurons, although there is no experimental evidence to support such a conjecture. We performed high temporal resolution studies of sodium currents gating in three types of central neurons. The results show that, within the tested voltage range from -55 to -35 mV, in all of these neurons, the activation time course of the current could be fit, after a brief delay, with a monoexponential function. The duration of delay from the start of the voltage command to the start of the extrapolated monoexponential fit was much smaller than predicted by the HH model. For example, in prefrontal cortex pyramidal neurons, at -46 mV and 12 degrees C, the observed average delay was 140 micros versus the 740 micros predicted by the two-gate HH model and the 1180 micros predicted by the three-gate HH model. These results can be explained by a model with two closed states and one open state. In this model, the transition between two closed states is approximately five times faster than the transition between the second closed state and the open state. This model captures all major properties of the sodium current activation. In addition, the proposed model reproduces the observed action potential shape more accurately than the traditional HH model. PMID:16407565

  18. Application of active quenching of second generation wire for current limiting

    SciTech Connect

    Solovyov, Vyacheslav F.; Li, Qiang

    2015-10-19

    Superconducting fault current limiters (SFCL's) are increasingly implemented in the power grid as a protection of substation equipment from fault currents. Resistive SFCL's are compact and light, however they are passively triggered and thus may not be sufficiently sensitive to respond to faults in the distribution grid. Here, we explore the prospect of adding an active management feature to a traditional resistive SFCL. A flexible radio-frequency coil, which is an integral part of the switching structure, acts as a triggering device. We show that the application of a short, 10 ms, burst of ac magnetic field during the fault triggers a uniform quench of the wire and significantly reduces the reaction time of the wire at low currents. The ac field burst generates a high density of normal zones, which merge into a continuous resistive region at a rate much faster than that of sparse normal zones created by the transport current alone.

  19. Application of active quenching of second generation wire for current limiting

    DOE PAGESBeta

    Solovyov, Vyacheslav F.; Li, Qiang

    2015-10-19

    Superconducting fault current limiters (SFCL's) are increasingly implemented in the power grid as a protection of substation equipment from fault currents. Resistive SFCL's are compact and light, however they are passively triggered and thus may not be sufficiently sensitive to respond to faults in the distribution grid. Here, we explore the prospect of adding an active management feature to a traditional resistive SFCL. A flexible radio-frequency coil, which is an integral part of the switching structure, acts as a triggering device. We show that the application of a short, 10 ms, burst of ac magnetic field during the fault triggersmore » a uniform quench of the wire and significantly reduces the reaction time of the wire at low currents. The ac field burst generates a high density of normal zones, which merge into a continuous resistive region at a rate much faster than that of sparse normal zones created by the transport current alone.« less

  20. Application of active quenching of second generation wire for current limiting

    NASA Astrophysics Data System (ADS)

    Solovyov, Vyacheslav F.; Li, Qiang

    2015-12-01

    Superconducting fault current limiters (SFCLs) are increasingly implemented in the power grid as a protection of substation equipment from fault currents. Resistive SFCLs are compact and light, however they are passively triggered and thus may not be sufficiently sensitive to respond to faults in the distribution grid. Here, we explore the prospect of adding an active management feature to a traditional resistive SFCL. A flexible radio-frequency coil, which is an integral part of the switching structure, acts as a triggering device. We show that the application of a short, 10 ms, burst of ac magnetic field during the fault triggers a uniform quench of the wire and significantly reduces the reaction time of the wire at low currents. The ac field burst generates a high density of normal zones, which merge into a continuous resistive region at a rate much faster than that of sparse normal zones created by the transport current alone.

  1. Propofol facilitates excitatory inputs of cerebellar Purkinje cells by depressing molecular layer interneuron activity during sensory information processing in vivo in mice.

    PubMed

    He, Yuan-Yuan; Jin, Ri; Jin, Wen-Zhe; Liu, Heng; Chu, Chun-Ping; Qiu, De-Lai

    2015-10-21

    Propofol is a rapid-acting sedative-hypnotic medication that has been widely used for the induction and maintenance of anesthesia; it has specific actions on different areas of the brain, such as sensory information transmission in the somatosensory cortex. However, the effects of propofol on the properties of sensory stimulation-evoked responses in cerebellar Purkinje cells (PCs) are currently unclear. In the present study, we studied the effects of propofol on facial stimulation-evoked responses in cerebellar PCs and molecular level interneurons (MLIs) in urethane-anesthetized mice using electrophysiological and pharmacological methods. Our results showed that cerebellar surface perfusion with propofol induced a decrease in the amplitude of the gamma-aminobutyric acid (GABA)-ergic component (P1) in a dose-dependent manner, but induced a significant increase in the amplitude of the excitatory response (N1). The IC50 of propofol-induced inhibition of P1 was 217.3 μM. In contrast, propofol (100 μM) depressed the spontaneous activity and tactile-evoked responses in MLIs. In addition, blocking GABA(A) receptor activity abolished the propofol (300 μM)-induced inhibition of the tactile-evoked inhibitory response and the increase in the sensory stimulation-evoked spike firing rate of PCs. These results indicated that propofol depressed the tactile stimulation-evoked spike firing of MLIs, resulting in a decrease in the amplitude of the tactile-evoked inhibitory response and an increase in the amplitude of the excitatory response in the cerebellar PCs of mice. Our results suggest that propofol modulates sensory information processing in cerebellar cortical PCs and MLIs through the activation of GABA(A) receptors. PMID:26317477

  2. Input Decimated Ensembles

    NASA Technical Reports Server (NTRS)

    Tumer, Kagan; Oza, Nikunj C.; Clancy, Daniel (Technical Monitor)

    2001-01-01

    Using an ensemble of classifiers instead of a single classifier has been shown to improve generalization performance in many pattern recognition problems. However, the extent of such improvement depends greatly on the amount of correlation among the errors of the base classifiers. Therefore, reducing those correlations while keeping the classifiers' performance levels high is an important area of research. In this article, we explore input decimation (ID), a method which selects feature subsets for their ability to discriminate among the classes and uses them to decouple the base classifiers. We provide a summary of the theoretical benefits of correlation reduction, along with results of our method on two underwater sonar data sets, three benchmarks from the Probenl/UCI repositories, and two synthetic data sets. The results indicate that input decimated ensembles (IDEs) outperform ensembles whose base classifiers use all the input features; randomly selected subsets of features; and features created using principal components analysis, on a wide range of domains.

  3. Physical Activity Behaviour: An Overview of Current and Emergent Theoretical Practices

    PubMed Central

    Buchan, Duncan S.; Ollis, Stewart; Thomas, Non E.; Baker, Julien S.

    2012-01-01

    Physical activity research has been dominated by traditional cognitive rationale paradigms utilized within other domains. Though this approach to physical activity behavior has greatly enhanced our understanding of the key determinants, it has done little to eradicate the health problems we currently face. In order to achieve lasting change though, multilevel interventions may prove effective. Ecological perspectives have been proposed as an effective approach in combating current physical inactivity levels. Nevertheless, this approach is in its infancy and much has still to be learned. The aim of this paper is to provide an overview of the main behavioral models used within the physical activity domain while proposing the need for further models that will embrace the principles presented by ecological and complexity theories. PMID:22778918

  4. Geochemists seek input

    NASA Astrophysics Data System (ADS)

    The U.S. National Committee for Geochemistry (USNC/Geochemistry) was established by the National Academy of Sciences in 1967 to provide a liaison between the Academy's working arm—the National Research Council—and the national and international community of geochemists. The USNC/Geochemistry wishes to enhance its visibility in the geochemical community by detailing here the structure and functions of the committee and by inviting direct communications from interested persons.Some projects that give a sense of the activities of the committee include the following items. A symposium on Multiple Fluid Flow in Crystalline Rocks at Elevated Temperatures is being planned by Maria Luisa Crawford at the fall 1983 annual Geological Society of America meeting. The symposium will bring together some overviews of fluid flow processes and the physical, chemical, and kinetic factors governing flow, as well as provide an opportunity for presentations of current research in this broad area.

  5. Calcium-activated chloride currents in primary cultures of rabbit distal convoluted tubule.

    PubMed

    Bidet, M; Tauc, M; Rubera, I; de Renzis, G; Poujeol, C; Bohn, M T; Poujeol, P

    1996-10-01

    Chloride (Cl-) conductances were studied in primary cultures of rabbit distal convoluted tubule (very early distal "bright" convoluted tubule, DCTb) by the whole cell patch-clamp technique. We identified a Cl- current activated by 2 microM extracellular ionomycin. The kinetics of the macroscopic current were time dependent for depolarizing potentials with a slow developing component. The steady state current presented outward rectification, and the ion selectivity sequence was I- > Br- > > Cl > glutamate. The current was inhibited by 0.1 mM 5-nitro-2-(3-phenylpropyl-amino)benzoic acid, 1 mM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, and 1 mM diphenylamine-2-carboxylate. To identify the location of the Cl- conductance, 6-methoxy-N-(3-sulfopropyl)quinolinium fluorescence experiments were carried out in confluent cultures developed on collagen-coated permeable filters. Cl- removal from the apical solution induced a Cl- efflux that was stimulated by 10 microM forskolin. Forskolin had no effect on the basolateral Cl- permeability Cl- substitution in the basolateral solution induced an efflux stimulated by 2 microM ionomycin or 50 microM extracellular ATP Ionomycin had no effect on the apical Cl- fluxes. Thus cultured DCTb cells exhibit Ca(2+)-activated Cl- channels located in the basolateral membrane. This Cl- permeability was active at a resting membrane potential and could participate in the Cl- reabsorption across the DCTb in control conditions. PMID:8898026

  6. Activation of chloride current by P2-purinoceptors in rat ventricular myocytes.

    PubMed Central

    Kaneda, M.; Fukui, K.; Doi, K.

    1994-01-01

    1. Rat ventricular myocytes were dissociated and their responses to extracellularly applied ATP were recorded using patch pipettes under the whole cell configuration. 2. ATP initially induced an inward current followed by an outward current at -50 mV. With a Cs-rich pipette solution the late outward current was blocked, leaving a sustained inward current (IATPs) suggesting that a K+ conductance underlies the late response. 3. When the extracellular Cl- concentration was changed, the reversal potential of IATPs corresponded well to the shift of the Cl- equilibrium potential. IATPs was reversibly blocked by the chloride channel blocker, 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS). 4. The concentration-response curve of IATPs had a Hill coefficient of 0.98 and an EC50 value of 5.2 x 10(-6) M. 5. ATP was more potent than ADP, while AMP and adenosine were ineffective, suggesting that P2-purinoceptor activation induced IATPs. 6. The activation of IATPs was depressed by depleting the extracellular Mg2+ and increased by adding Mg2+. 7. Our results strongly suggest that P2-purinoceptor activation by ATP induces both a Cl(-)-conductance (IATPs) and a K(+)-conductance in rat ventricular myocytes. PMID:8032621

  7. Photospheric Vertical Current Density and Overlying Atmospheric Activity in an Emerging Flux Region

    NASA Astrophysics Data System (ADS)

    Georgoulis, M. K.; Rust, D. M.; Bernasconi, P. N.; Schmieder, B.

    2002-05-01

    Using high-resolution vector magnetograms obtained by the balloon-borne Flare Genesis Experiment (FGE), we construct maps of the vertical current density in the emerging flux region NOAA 8844. The vertical current density has been decomposed into components that are field-aligned and perpendicular to the magnetic field, thus allowing a straightforward identification of force-free areas, as well as of areas where the force-free approximation breaks down. Small-scale chromospheric activity, such as H α Ellerman bombs and Ultraviolet bright points in 1600 Åshow a remarkable correlation with areas of strong current density. Simultaneous data of overlying coronal loops, observed by TRACE in the Extreme Ultraviolet (171 Åand 195 Å), have been carefully co-aligned with the FGE photospheric maps. We find that the footpoints of the TRACE loops always coincide with strong vertical currents and enhancements of the current helicity density. We also investigate whether the force-free approximation is valid on the photosphere during various evolutionary stages of the active region.

  8. The morphology of flare phenomena, magnetic fields, and electric currents in active regions. II - NOAA active region 5747 (1989 October)

    NASA Technical Reports Server (NTRS)

    Leka, K. D.; Canfield, Richard C.; Mcclymont, A. N.; De La Beaujardiere, J.-F.; Fan, Yuhong; Tang, F.

    1993-01-01

    The paper describes October 1989 observations in NOAA Active Region 5747 of the morphology of energetic electron precipitation and high-pressure coronal flare plasmas of three flares and their relation to the vector magnetic field and vertical electric currents. The H-alpha spectroheliograms were coaligned with the vector magnetograms using continuum images of sunspots, enabling positional accuracy of a few arcsec. It was found that, during the gradual phase, the regions of the H-alpha flare that show the effects of enhanced pressure in the overlying corona often encompass extrema of the vertical current density, consistent with earlier work showing a close relationship between H-alpha emission and line-of-sight currents. The data are also consistent with the overall morphology and evolution described by erupting-filament models such as those of Kopp and Pneuman (1976) and Sturrock (1989).

  9. Characterization of volume-activated chloride currents in regulatory volume decrease of human cholangiocyte.

    PubMed

    Chen, Biyi; Jefferson, Douglas M; Cho, Won Kyoo

    2010-05-01

    Volume-activated chloride channel (VACC) plays vital roles in many physiological functions. In bile duct epithelium, VACC actively participates in biliary secretion and cell volume regulation, and it mediates regulatory volume decrease (RVD). Recently, we have shown that mouse cholangiocytes have an intact RVD via VACC and K(+) conductance. However, such cell volume regulation was not studied in the normal human cholangiocyte. Volume measurement by Coulter counter and whole-cell patch clamp technique were used to characterize the RVD and VACC in human cholangiocyte cell line (HBDC). When exposed to hypotonic solution, HBDC exhibited an intact RVD, which was inhibited by 1,2-Bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester) (BAPTA-AM), NPPB (5-nitro-2'- (3-phenylpropylamino)-benzoate), DIDS (4,4'-diisothiocyanatostilbene-2-disulfonic acid), and tamoxifen, but was not affected by the removal of extracellular calcium. During RVD, HBDC exhibited large, outwardly rectifying currents and time-dependent inactivation at positive potential. The amplitude of the outward current was approximately 3 times of that of the inward current, and this volume-activated current returned to the baseline when switched to isotonic solution. The amplitude and reversal potential of the volume-activated current was dependent on Cl(-) concentration, and the VACC was significantly inhibited by replacing chloride with gluconate, glutamate, sucrose, and acetate in the hypotonic solution. In addition, classical VACC inhibitors, such as NPPB or tamoxifen, inhibited the VACC. These inhibitory effects were reversible with washing out the inhibitors from the bath solution. The present study is the first to characterize and show that HBDC has an intact RVD, mediated by VACC, which has similar electrophysiological characteristics as that in mouse cholangiocytes. PMID:20411247

  10. Magnetic current sensor

    NASA Technical Reports Server (NTRS)

    Black, Jr., William C. (Inventor); Hermann, Theodore M. (Inventor)

    1998-01-01

    A current determiner having an output at which representations of input currents are provided having an input conductor for the input current and a current sensor supported on a substrate electrically isolated from one another but with the sensor positioned in the magnetic fields arising about the input conductor due to any input currents. The sensor extends along the substrate in a direction primarily perpendicular to the extent of the input conductor and is formed of at least a pair of thin-film ferromagnetic layers separated by a non-magnetic conductive layer. The sensor can be electrically connected to a electronic circuitry formed in the substrate including a nonlinearity adaptation circuit to provide representations of the input currents of increased accuracy despite nonlinearities in the current sensor, and can include further current sensors in bridge circuits.

  11. Calcium-activated inward spike after-currents in bursting neurone R15 of Aplysia.

    PubMed Central

    Lewis, D V

    1988-01-01

    1. Slow inward and outward after-currents follow action potentials in the bursting pacemaker neurone, R 15, of Aplysia californica. These experiments were performed to examine the role of axo-dendritic calcium influx in activating these after currents. 2. Depolarizing voltage-clamp commands issued at the soma were used to elicit the after-currents. The earlier inward depolarizing after-current of DAC was followed by the hyperpolarizing after-current or HAC. The DAC and HAC appeared at a threshold following depolarizing commands in normal sea water, presumably due to triggering of action potentials in inadequately space-clamped axon. In 100 microM-tetrodotoxin (TTX), the after-currents were graded, increasing gradually in amplitude with increasing voltage or duration of the command. 3. After-current amplitudes varied with the holding potential through the range tested, -40 to -80 mV. DACs were maximum at -40 to -50 mV and decreased in amplitude with hyperpolarization. HACs were maximum at -40 mV and decreased with hyperpolarization to disappear between -70 and -80 mV. 4. The dependence of after-currents upon intracellular calcium accumulation during the depolarizing command was tested in several ways. Bathing R15 in 0 Ca2+-2 mM-EGTA (ethyleneglycol-bis-(beta-aminoethylether)-N,N'-tetraacetic acid) sea water eliminated the after-currents. Bathing in 1 mM-Ca2+ sea water reduced the DAC by 76% and the HAC by 87% following 10 ms long depolarizations to +40 mV. Application of Mn2+ (25 mM) or La3+ (5 mM) blocked the after-currents. Injection of EGTA intracellularly practically eliminated after-currents. Greatly prolonged depolarizations were required to elicit them after EGTA injection. Substitution of Ba2+ for Ca2+ also eliminated after-currents. 5. Sodium-free sea water eliminated the DAC. The HAC following brief (less than 30 ms) depolarizing commands was also eliminated in zero sodium, although longer commands were followed by an outward tail current. 6. Although the

  12. A self-sensing active magnetic bearing based on a direct current measurement approach.

    PubMed

    Niemann, Andries C; van Schoor, George; du Rand, Carel P

    2013-01-01

    Active magnetic bearings (AMBs) have become a key technology in various industrial applications. Self-sensing AMBs provide an integrated sensorless solution for position estimation, consolidating the sensing and actuating functions into a single electromagnetic transducer. The approach aims to reduce possible hardware failure points, production costs, and system complexity. Despite these advantages, self-sensing methods must address various technical challenges to maximize the performance thereof. This paper presents the direct current measurement (DCM) approach for self-sensing AMBs, denoting the direct measurement of the current ripple component. In AMB systems, switching power amplifiers (PAs) modulate the rotor position information onto the current waveform. Demodulation self-sensing techniques then use bandpass and lowpass filters to estimate the rotor position from the voltage and current signals. However, the additional phase-shift introduced by these filters results in lower stability margins. The DCM approach utilizes a novel PA switching method that directly measures the current ripple to obtain duty-cycle invariant position estimates. Demodulation filters are largely excluded to minimize additional phase-shift in the position estimates. Basic functionality and performance of the proposed self-sensing approach are demonstrated via a transient simulation model as well as a high current (10 A) experimental system. A digital implementation of amplitude modulation self-sensing serves as a comparative estimator. PMID:24030681

  13. A Self-Sensing Active Magnetic Bearing Based on a Direct Current Measurement Approach

    PubMed Central

    Niemann, Andries C.; van Schoor, George; du Rand, Carel P.

    2013-01-01

    Active magnetic bearings (AMBs) have become a key technology in various industrial applications. Self-sensing AMBs provide an integrated sensorless solution for position estimation, consolidating the sensing and actuating functions into a single electromagnetic transducer. The approach aims to reduce possible hardware failure points, production costs, and system complexity. Despite these advantages, self-sensing methods must address various technical challenges to maximize the performance thereof. This paper presents the direct current measurement (DCM) approach for self-sensing AMBs, denoting the direct measurement of the current ripple component. In AMB systems, switching power amplifiers (PAs) modulate the rotor position information onto the current waveform. Demodulation self-sensing techniques then use bandpass and lowpass filters to estimate the rotor position from the voltage and current signals. However, the additional phase-shift introduced by these filters results in lower stability margins. The DCM approach utilizes a novel PA switching method that directly measures the current ripple to obtain duty-cycle invariant position estimates. Demodulation filters are largely excluded to minimize additional phase-shift in the position estimates. Basic functionality and performance of the proposed self-sensing approach are demonstrated via a transient simulation model as well as a high current (10 A) experimental system. A digital implementation of amplitude modulation self-sensing serves as a comparative estimator. PMID:24030681

  14. Characterization of T-type calcium current and its contribution to electrical activity in rabbit urethra.

    PubMed

    Bradley, J E; Anderson, U A; Woolsey, S M; Thornbury, K D; McHale, N G; Hollywood, M A

    2004-05-01

    Rabbit urethral smooth muscle cells were studied at 37 degrees C by using the amphotericin B perforated-patch configuration of the patch-clamp technique, using Cs(+)-rich pipette solutions. Two components of current, with electrophysiological and pharmacological properties typical of T- and L-type Ca(2+) currents, were recorded. Fitting steady-state inactivation curves for the L current with a Boltzmann equation yielded a V(1/2) of -41 +/- 3 mV. In contrast, the T current inactivated with a V(1/2) of -76 +/- 2 mV. The L currents were reduced by nifedipine (IC(50) = 225 +/- 84 nM), Ni(2+) (IC(50) = 324 +/- 74 microM), and mibefradil (IC(50) = 2.6 +/- 1.1 microM) but were enhanced when external Ca(2+) was substituted with Ba(2+). The T current was little affected by nifedipine at concentrations <300 nM but was increased in amplitude when external Ca(2+) was substituted with Ba(2+). Both Ni(2+) and mibefradil reduced the T current with an IC(50) = 7 +/- 1 microM and approximately 40 nM, respectively. Spontaneous electrical activity recorded with intracellular electrodes from strips of rabbit urethra consisted of complexes comprising a series of spikes superimposed on a slow spontaneous depolarization (SD). Inhibition of T current reduced the frequency of these SDs but had no effect on either the number of spikes per complex or the amplitude of the spikes. In contrast, application of nifedipine failed to significantly alter the frequency of the SD but reduced the number and amplitude of the spikes in each complex. PMID:15075207

  15. ATP-activated P2X2 current in mouse spermatozoa

    PubMed Central

    Navarro, Betsy; Miki, Kiyoshi; Clapham, David E.

    2011-01-01

    Sperm cells acquire hyperactivated motility as they ascend the female reproductive tract, which enables them to overcome barriers and penetrate the cumulus and zona pellucida surrounding the egg. This enhanced motility requires Ca2+ entry via cation channel of sperm (CatSper) Ca2+-selective ion channels in the sperm tail. Ca2+ entry via CatSper is enhanced by the membrane hyperpolarization mediated by Slo3, a K+ channel also present in the sperm tail. To date, no transmitter-mediated currents have been reported in sperm and no currents have been detected in the head or midpiece of mature spermatozoa. We screened a number of neurotransmitters and biomolecules to examine their ability to induce ion channel currents in the whole spermatozoa. Surprisingly, we find that none of the previously reported neurotransmitter receptors detected by antibodies alone are functional in mouse spermatozoa. Instead, we find that mouse spermatozoa have a cation-nonselective current in the midpiece of spermatozoa that is activated by external ATP, consistent with an ATP-mediated increase in intracellular Ca2+ as previously reported. The ATP-dependent current is not detected in mice lacking the P2X2 receptor gene (P2rx2−/−). Furthermore, the slowly desensitizing and strongly outwardly rectifying ATP-gated current has the biophysical and pharmacological properties that mimic heterologously expressed mouse P2X2. We conclude that the ATP-induced current on mouse spermatozoa is mediated by the P2X2 purinergic receptor/channel. Despite the loss of ATP-gated current, P2rx2−/− spermatozoa have normal progressive motility, hyperactivated motility, and acrosome reactions. However, fertility of P2rx2−/− males declines with frequent mating over days, suggesting that P2X2 receptor adds a selection advantage under these conditions. PMID:21831833

  16. Properties of a calcium-activated K(+) current on interneurons in the developing rat hippocampus.

    PubMed

    Aoki, T; Baraban, S C

    2000-06-01

    Calcium-activated potassium currents have an essential role in regulating excitability in a variety of neurons. Although it is well established that mature CA1 pyramidal neurons possess a Ca(2+)-activated K(+) conductance (I(K(Ca))) with early and late components, modulation by various endogenous neurotransmitters, and sensitivity to K(+) channel toxins, the properties of I(K(Ca)) on hippocampal interneurons (or immature CA1 pyramidal neurons) are relatively unknown. To address this problem, whole-cell voltage-clamp recordings were made from visually identified interneurons in stratum lacunosum-moleculare (L-M) and CA1 pyramidal cells in hippocampal slices from immature rats (P3-P25). A biphasic calcium-activated K(+) tail current was elicited following a brief depolarization from the holding potential (-50 mV). Analysis of the kinetic properties of I(K(Ca)) suggests that an early current component differs between these two cell types. An early I(K(Ca)) with a large peak current amplitude (200.8 +/- 13.2 pA, mean +/- SE), slow time constant of decay (70.9 +/- 3.3 ms), and relatively rapid time to peak (within 15 ms) was observed on L-M interneurons (n = 88), whereas an early I(K(Ca)) with a small peak current amplitude (112.5 +/- 7.3 pA), a fast time constant of decay (39.4 +/- 1.6 ms), and a slower time-to-peak (within 26 ms) was observed on CA1 pyramidal neurons (n = 85). Removal of extracellular calcium or addition of inorganic Ca(2+) channel blockers (cadmium, nickel, or cobalt) was used to demonstrate the calcium dependence of these currents. Addition of norepinephrine, carbachol, and a variety of channel toxins (apamin, iberiotoxin, verruculogen, paxilline, penitrem A, and charybdotoxin) were used to further distinguish between I(K(Ca)) on these two hippocampal cell types. Verruculogen (100 nM), carbachol (100 microM), apamin (100 nM), TEA (1 mM), and iberiotoxin (50 nM) significantly reduced early I(K(Ca)) on CA1 pyramidal neurons; early I(K(Ca)) on L

  17. An active sensor for monitoring bearing wear by means of an eddy current displacement sensor

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Toshihiko; Ueda, Masahiro

    2007-01-01

    A new and simple sensor for directly monitoring bearing wear has been developed by improving an eddy current displacement sensor. The sensor can be applied for non-metal shafts as well as metal shafts, and in this sense, we call it an 'active sensor'. In this sensor, an aluminium foil, used as a target metal for the eddy current sensor, has been sandwiched between two wedge-shaped acrylic plates and combined with an eddy current displacement sensor as a unit. The whole system consists of this new sensor, a data processing system including an amplifier, a 14-bit A/D converter, a personal computer and a display. The error of this system was about 20 µm, which was sufficiently small for use in a practical plant.

  18. Quantum-classical transition and quantum activation of ratchet currents in the parameter space.

    PubMed

    Beims, M W; Schlesinger, M; Manchein, C; Celestino, A; Pernice, A; Strunz, W T

    2015-05-01

    The quantum ratchet current is studied in the parameter space of the dissipative kicked rotor model coupled to a zero-temperature quantum environment. We show that vacuum fluctuations blur the generic isoperiodic stable structures found in the classical case. Such structures tend to survive when a measure of statistical dependence between the quantum and classical currents are displayed in the parameter space. In addition, we show that quantum fluctuations can be used to overcome transport barriers in the phase space. Related quantum ratchet current activation regions are spotted in the parameter space. Results are discussed based on quantum, semiclassical, and classical calculations. While the semiclassical dynamics involves vacuum fluctuations, the classical map is driven by thermal noise. PMID:26066230

  19. Evolution of sunspot activity and inversion of the Sun's polar magnetic field in the current cycle

    NASA Astrophysics Data System (ADS)

    Mordvinov, A. V.; Grigoryev, V. M.; Erofeev, D. V.

    2015-06-01

    A spatiotemporal analysis of the Sun's magnetic field was carried out to study the polar-field inversion in the current cycle in relation to sunspot activity. The causal relationship between these phenomena was demonstrated in a time-latitude aspect. After decay of long-lived activity complexes their magnetic fields were redistributed into the surrounding photosphere and formed unipolar magnetic regions which were transported to high latitudes. Zones of intense sunspot activity during 2011/2012 produced unipolar magnetic regions of the following polarities, whose poleward drift led to the inversion of the Sun's polar fields at the North and South Poles. At the North Pole the polar field reversal was completed by May 2013. It was demonstrated that mixed magnetic polarities near the North Pole resulted from violations of Joy's law at lower latitudes. Later sunspot activity in the southern hemisphere has led to a delay in magnetic polarity reversal at the South Pole. Thus, the north-south asymmetry of sunspot activity resulted in asynchronous polar field reversal in the current cycle.

  20. Spin-wave activation by spin-polarized current pulse in magnetic nanopillars

    NASA Astrophysics Data System (ADS)

    Montoncello, Federico; Giovannini, Loris; Nizzoli, Fabrizio; Zivieri, Roberto; Consolo, Giancarlo; Gubbiotti, Gianluca

    2010-08-01

    We demonstrate the role of spin-polarized current pulse in activating only a subset of spin-wave normal modes in laterally confined magnetic systems. In order to derive selection rules based on geometrical considerations, the study was carried out by comparing the results of two different micromagnetic frameworks (a classical finite-difference time-domain scheme and the dynamical matrix method) and considering nanopillar devices of elliptical and circular cross-sections in different magnetic ground states (onion, S, and vortex states). The analogies and the differences existing between the mode activation process driven by spin-torque and that obtained by a magnetic field pulse are also addressed.

  1. Phorbol ester activation of chloride current in guinea-pig ventricular myocytes.

    PubMed Central

    Shuba, L. M.; Asai, T.; McDonald, T. F.

    1996-01-01

    1. Although earlier studies with phorbol esters indicate that protein kinase C (PKC) may be an important regulator of Cl- current (Icl) in cardiac cells, there is a need for additional quantitative data and investigation of conflicting findings. Our objectives were to measure the magnitude, time course, and concentration-dependence of Icl activated in guinea-pig ventricular myocytes by phorbol 12-myristate 13-acetate (PMA), evaluate its PKC dependence, and examine its modification by external and internal ions. 2. The whole-cell patch clamp technique was used to apply short depolarizing and hyperpolarizing pulses to myocytes superfused with Na(+)-, K(+)-, Ca(2+)-free solution (36 degrees C) and dialysed with Cs+ solution. Stimulation of membrane currents by PMA (threshold < or = 1nM, EC50 approximately equal to 14 nM, maximal 40% increase with > or = 100 nM) plateaued within 6-10 min. 3. PMA-activated current was time-independent, and suppressed by l mM 9-anthracenecarboxylic acid (9-AC). Its reversal potential (Erev) was sensitive to changes in the Cl- gradient, and outward rectification of the current-voltage (I-V) relationship was more pronounced with 30 mM than 140 mM Cl- dialysate. 4. The relative permeability of PMA-activated channels estimated from Erev measurements was I- > Cl- > > aspartate. Channel activation was independent of external Na+. 5. PMA failed to activate Icl in myocytes pretreated with 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7) or dialysed with pCa 10.5 solution. Lack of response to 4 alpha-phorbol 12, 13-didecanoate (alpha PDD) was a further indication of mediation by PKC. 6. Icl induced by 2 microM forskolin was far larger than that induced by PMA, suggesting that endogenous protein kinase A is a much stronger Cl- channel activator than endogenous PKC in these myocytes. 7. The macroscopic properties of PMA-induced Icl appear to be indistinguishable from those of PKA-activated Icl. We discount stimulation of PKA by PMA as an

  2. High Efficiency Alternating Current Driven Organic Light Emitting Devices Employing Active Semiconducting Gate Layers

    NASA Astrophysics Data System (ADS)

    Smith, Gregory; Xu, Junwei; Carroll, David

    2015-03-01

    In this work, we describe the role of semiconductor-polymer interfaces in alternating current (AC) driven organic electroluminescent (EL) devices. We implement inorganic semiconducting materials between the external contact and the active layers in organic light EL devices. Precise control of capacitance and charge injection is required to realize bright and efficient large area AC driven devices. We show how this architecture results in active gating to the polymer layers, resulting in the novel ability to control the capacitance and charge injection characteristics. We propose a model based on band bending at the semiconductor-polymer interface. Furthermore, we elucidate the influence of the semiconductor-polymer interface on the internally coupled magnetic field generated in an alternating current driven organic light emitting device configuration. Magnetic fields can alter the ratios of singlet and triplet populations, and we show that internal generation of a magnetic field can dramatically alter the efficiency of light emission in organic EL devices.

  3. Active to sterile neutrino mixing limits from neutral-current interactions in MINOS.

    PubMed

    Adamson, P; Auty, D J; Ayres, D S; Backhouse, C; Barr, G; Bishai, M; Blake, A; Bock, G J; Boehnlein, D J; Bogert, D; Cavanaugh, S; Cherdack, D; Childress, S; Coelho, J A B; Coleman, S J; Corwin, L; Cronin-Hennessy, D; Danko, I Z; de Jong, J K; Devenish, N E; Diwan, M V; Dorman, M; Escobar, C O; Evans, J J; Falk, E; Feldman, G J; Frohne, M V; Gallagher, H R; Gomes, R A; Goodman, M C; Gouffon, P; Graf, N; Gran, R; Grant, N; Grzelak, K; Habig, A; Harris, D; Hartnell, J; Hatcher, R; Himmel, A; Holin, A; Huang, X; Hylen, J; Ilic, J; Irwin, G M; Isvan, Z; Jaffe, D E; James, C; Jensen, D; Kafka, T; Kasahara, S M S; Koizumi, G; Kopp, S; Kordosky, M; Kreymer, A; Lang, K; Lefeuvre, G; Ling, J; Litchfield, P J; Loiacono, L; Lucas, P; Mann, W A; Marshak, M L; Mayer, N; McGowan, A M; Mehdiyev, R; Meier, J R; Messier, M D; Miller, W H; Mishra, S R; Mitchell, J; Moore, C D; Morfín, J; Mualem, L; Mufson, S; Musser, J; Naples, D; Nelson, J K; Newman, H B; Nichol, R J; Nicholls, T C; Nowak, J A; Oliver, W P; Orchanian, M; Paley, J; Patterson, R B; Pawloski, G; Pearce, G F; Petyt, D A; Phan-Budd, S; Pittam, R; Plunkett, R K; Qiu, X; Ratchford, J; Raufer, T M; Rebel, B; Rodrigues, P A; Rosenfeld, C; Rubin, H A; Sanchez, M C; Schneps, J; Schreiner, P; Sharma, R; Shanahan, P; Sousa, A; Stamoulis, P; Strait, M; Tagg, N; Talaga, R L; Tetteh-Lartey, E; Thomas, J; Thomson, M A; Tinti, G; Toner, R; Torretta, D; Tzanakos, G; Urheim, J; Vahle, P; Viren, B; Walding, J J; Weber, A; Webb, R C; White, C; Whitehead, L; Wojcicki, S G; Zwaska, R

    2011-07-01

    Results are reported from a search for active to sterile neutrino oscillations in the MINOS long-baseline experiment, based on the observation of neutral-current neutrino interactions, from an exposure to the NuMI neutrino beam of 7.07×10(20) protons on target. A total of 802 neutral-current event candidates is observed in the Far Detector, compared to an expected number of 754 ± 28(stat) ± 37(syst) for oscillations among three active flavors. The fraction f(s) of disappearing ν(μ) that may transition to ν(s) is found to be less than 22% at the 90% C.L. PMID:21797535

  4. Active to Sterile Neutrino Mixing Limits from Neutral-Current Interactions in MINOS

    SciTech Connect

    Adamson, P.; Bock, G. J.; Boehnlein, D. J.; Bogert, D.; Childress, S.; Harris, D.; Hatcher, R.; Hylen, J.; James, C.; Jensen, D.; Koizumi, G.; Kreymer, A.; Lucas, P.; Moore, C. D.; Morfin, J.; Plunkett, R. K.; Rebel, B.; Sharma, R.; Shanahan, P.; Torretta, D.

    2011-07-01

    Results are reported from a search for active to sterile neutrino oscillations in the MINOS long-baseline experiment, based on the observation of neutral-current neutrino interactions, from an exposure to the NuMI neutrino beam of 7.07x10{sup 20} protons on target. A total of 802 neutral-current event candidates is observed in the Far Detector, compared to an expected number of 754{+-}28(stat){+-}37(syst) for oscillations among three active flavors. The fraction f{sub s} of disappearing {nu}{sub {mu}} that may transition to {nu}{sub s} is found to be less than 22% at the 90% C.L.

  5. Active to sterile neutrino mixing limits from neutral-current interactions in MINOS

    SciTech Connect

    Adamson, P.; Auty, D.J.; Ayres, D.S.; Backhouse, C.; Barr, G.; Bishai, M.; Blake, A.; Bock, G.J.; Boehnlein, D.J.; Bogert, D.; Cavanaugh, S.; /Harvard U., Phys. Dept. /Tufts U.

    2011-04-01

    Results are reported from a search for active to sterile neutrino oscillations in the MINOS long-baseline experiment, based on the observation of neutral-current neutrino interactions, from an exposure to the NuMI neutrino beam of 7.07 x 10{sup 20} protons on target. A total of 802 neutral-current event candidates is observed in the Far Detector, compared to an expected number of 754 {+-} 28(stat.) {+-} 37(syst.) for oscillations among three active flavors. The fraction f{sub s} of disappearing {nu}{sub {mu}} that may transition to {nu}{sub s} is found to be less than 22% at the 90% C.L.

  6. Current California legislative and regulatory activity impacting geothermal hydrothermal commercialization: a monitoring report. Report No. 1017

    SciTech Connect

    Not Available

    1980-01-20

    Four key geothermal-impacting bills presently before the California legislature are described. Two deal with state financial backing for geothermal projects. The third relates to the use of the state's share of the BLM geothermal revenues and the fourth to the protection of sensitive hot springs. The current regulatory activities of the California Energy Commission, the California Division of Oil and Gas, and the counties are discussed. (MHR)

  7. Central European MetEor NeTwork: Current status and future activities

    NASA Astrophysics Data System (ADS)

    Srba, J.; Koukal, J.; Ferus, M.; Lenža, L.; Gorková, S.; Civiš, S.; Simon, J.; Csorgei, T.; Jedlièka, M.; Korec, M.; Kaniansky, S.; Polák, J.; Spurný, M.; Brázdil, T.; Mäsiar, J.; Zima, M.; Delinèák, P.; Popek, M.; Bahýl, V.; Piffl, R.; Èechmánek, M.

    2016-06-01

    The Central European video Meteor Network (CEMeNt) established in 2010 is a platform for cross-border cooperation in the field of video meteor observations between Czech Republic and Slovakia. During five years of operation the CEMeNt network went through an extensive development. In total, 37 video systems were working on 20 permanent stations located in Czech Republic and Slovakia during 2015. In this paper we summarize CEMeNt current status and introduce some future activities.

  8. A Mathematical Model of Neonatal Rat Atrial Monolayers with Constitutively Active Acetylcholine-Mediated K+ Current

    PubMed Central

    Majumder, Rupamanjari; Jangsangthong, Wanchana; Feola, Iolanda; Ypey, Dirk L.; Pijnappels, Daniël A.; Panfilov, Alexander V.

    2016-01-01

    Atrial fibrillation (AF) is the most frequent form of arrhythmia occurring in the industrialized world. Because of its complex nature, each identified form of AF requires specialized treatment. Thus, an in-depth understanding of the bases of these arrhythmias is essential for therapeutic development. A variety of experimental studies aimed at understanding the mechanisms of AF are performed using primary cultures of neonatal rat atrial cardiomyocytes (NRAMs). Previously, we have shown that the distinct advantage of NRAM cultures is that they allow standardized, systematic, robust re-entry induction in the presence of a constitutively-active acetylcholine-mediated K+ current (IKACh-c). Experimental studies dedicated to mechanistic explorations of AF, using these cultures, often use computer models for detailed electrophysiological investigations. However, currently, no mathematical model for NRAMs is available. Therefore, in the present study we propose the first model for the action potential (AP) of a NRAM with constitutively-active acetylcholine-mediated K+ current (IKACh-c). The descriptions of the ionic currents were based on patch-clamp data obtained from neonatal rats. Our monolayer model closely mimics the action potential duration (APD) restitution and conduction velocity (CV) restitution curves presented in our previous in vitro studies. In addition, the model reproduces the experimentally observed dynamics of spiral wave rotation, in the absence and in the presence of drug interventions, and in the presence of localized myofibroblast heterogeneities. PMID:27332890

  9. A fast transient potassium current in thalamic relay neurons: kinetics of activation and inactivation.

    PubMed

    Huguenard, J R; Coulter, D A; Prince, D A

    1991-10-01

    1. Whole-cell voltage-clamp techniques were used to record K+ currents in relay neurons (RNs) that had been acutely isolated from rat thalamic ventrobasal complex and maintained at 23 degrees C in vitro. Tetrodoxin (TTX; 0.5 microM) was used to block Na+ currents, and reduced extracellular levels of Ca2+ (1 mM) were used to minimize contributions from Ca2+ current (ICa). 2. In RNs, depolarizing commands activate K+ currents characterized by a substantial rapidly inactivating (time constant approximately 20 ms) component, the features of which correspond to those of the transient K+ current (IA) in other preparations, and by a smaller, more slowly activating K+ current, "IK". IA was reversibly blocked by 4-aminopyridine (4-AP, 5 mM), and the reversal potential varied with [K+]o as predicted by the Nernst equation. 3. IA was relatively insensitive to blockade by tetraethylammonium [TEA; 50%-inhibitory concentration (IC50) much much greater than 20 mM]; however, two components of IK were blocked with IC50S of 30 microM and 3 mM. Because 20 mM TEA blocked 90% of the sustained current while reducing IA by less than 10%, this concentration was routinely used in experiments in which IA was isolated and characterized. To further minimize contamination by other conductances, 4-AP was added to TEA-containing solutions and the 4-AP-sensitive current was obtained by subtraction. 4. Voltage-dependent steady-state inactivation of peak IA was described by a Boltzman function with a slope factor (k) of -6.5 and half-inactivation (V1/2) occurring at -75 mV. Activation of IA was characterized by a Boltzman curve with V1/2 = -35 mV and k = 10.8. 5. IA activation and inactivation kinetics were best fitted by the Hodgkin-Huxley m4h formalism. The rate of activation was voltage dependent, with tau m decreasing from 2.3 ms at -40 mV to 0.5 ms at +50 mV. Inactivation was relatively voltage independent and nonexponential. The rate of inactivation was described by two exponential decay

  10. Current Source Converters in Discontinuous Conduction Modes of Operation

    NASA Astrophysics Data System (ADS)

    Cuzner, Robert M.

    This work demonstrates that Current Source Rectifier (CSR) pulse-width modulation (PWM) can be successfully modified for discontinuous conduction mode (DCM). DCM is characterized by input current distortion and non-linear input to output voltage ratio. A Dead-Beat Current Injection (DBCI) PWM method is developed that ensures sinusoidal input currents and linear input to output voltage control while in DCM. A method for control analysis is proposed that enables design of the CSR closed loop voltage controller. The proposed method is simulated to show that the desired objectives are achieved at no load and very light load, where the CSR operates in an extreme DCM condition. Experimental results verify performance of the DBCI-PWM method and validate both simulation and analytical tools used to explore the capabilities of the approach. Index Terms---Active buck rectifier, Current source rectifier (CSR), current source PWM rectifier, power conversion, power converter design, power converter analysis, input power quality

  11. Current in vitro high throughput screening approaches to assess nuclear receptor activation.

    PubMed

    Raucy, Judy L; Lasker, Jerome M

    2010-11-01

    The screening of new drug candidates for nuclear receptor activation can identify agents with the potential to produce drug-drug interactions or elicit adverse drug effects. The nuclear receptors of interest are those that control the expression of drug metabolizing enzymes and drug transporters, and include the constitutive androstane receptor (CAR, NR1I3), the pregnane X receptor (PXR, NR1I2) and the aryl hydrocarbon receptor (AhR). This review will focus on the methods currently used to assess activation of these receptors. Assessment of nuclear receptor activation can be accomplished using direct or indirect approaches. Indirect methods quantify specific gene products that result from nuclear receptor activation while direct approaches measure either the binding of ligands to the receptors or the transcriptional events produced by ligand binding. Assays that directly quantify nuclear receptor activation are growing in popularity and, importantly, are amenable to high throughput screening (HTS). Several ligand binding assays are currently being utilized, including radioligand competition binding, where compounds compete with radiolabelled ligand for binding to PXR or CAR, such as the scintillation proximity binding assay that measures the reaction of ligands with receptor-coated beads. A fluorescence resonance energy transfer assay has also been developed, where the fluorescent signal is generated via the ligand-dependent interaction between the fluorescently-labeled ligand binding domain of a nuclear receptor and co-activator proteins. Other in vitro activation assays include transient- and stably-transfected cell lines incorporating an expression vector for PXR, CAR or AhR plus a reporter gene vector containing response elements. The methods focused on in this review will be limited to the more direct in vitro approaches that are amenable to high throughput screening. PMID:21189134

  12. Photospheric electric current and transition region brightness within an active region

    NASA Technical Reports Server (NTRS)

    Deloach, A. C.; Hagyard, M. J.; Rabin, D.; Moore, R. L.; Smith, B. J., Jr.; West, E. A.; Tandberg-Hanssen, E.

    1984-01-01

    Distributions of vertical electrical current density J(z) calculated from vector measurements of the photospheric magnetic field are compared with ultraviolet spectroheliograms to investigate whether resistive heating is an important source of enhanced emission in the transition region. The photospheric magnetic fields in Active Region 2372 were measured on April 6 and 7, 1980 with the Marshall Space Flight Center vector magnetograph; ultraviolet wavelength spectroheliograms (L-alpha and N V 1239 A) were obtained with the UV Spectrometer and Polarimeter experiment aboard the Solar Maximum Mission satellite. Spatial registration of the J(z) (5 arcsec resolution) and UV (3 arcsec resolution) maps indicates that the maximum current density is cospatial with a minor but persistent UV enhancement, but there is little detected current associated with other nearby bright areas. It is concluded that, although resistive heating may be important in the transition region, the currents responsible for the heating are largely unresolved in the present measurements and have no simple correlation with the residual current measured on 5-arcsec scales.

  13. Antibiofilm Activity of Low-Amperage Continuous and Intermittent Direct Electrical Current

    PubMed Central

    Schmidt-Malan, Suzannah M.; Karau, Melissa J.; Cede, Julia; Greenwood-Quaintance, Kerryl E.; Brinkman, Cassandra L.; Mandrekar, Jayawant N.

    2015-01-01

    Bacterial biofilms are difficult to treat using available antimicrobial agents, so new antibiofilm strategies are needed. We previously showed that 20, 200, and 2,000 μA of electrical current reduced bacterial biofilms of Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa. Here, we tested continuous direct current at lower amperages, intermittent direct current, and combinations of surface materials (Teflon or titanium) and electrode compositions (stainless steel, graphite, titanium, or platinum) against S. aureus, S. epidermidis, and P. aeruginosa biofilms. In addition, we tested 200 or 2,000 μA for 1 and 4 days against biofilms of 33 strains representing 13 species of microorganisms. The logarithmic reduction factor was used to measure treatment effects. Using continuous current delivery, the lowest active amperage was 2 μA for 1, 4, or 7 days against P. aeruginosa and 5 μA for 7 days against S. epidermidis and S. aureus biofilms. Delivery of 200 μA for 4 h a day over 4 days reduced P. aeruginosa, S. aureus, and S. epidermidis biofilms on Teflon or titanium discs. A reduction of P. aeruginosa, S. aureus, and S. epidermidis biofilms was measured for 23 of 24 combinations of surface materials and electrode compositions tested. Four days of direct current delivery reduced biofilms of 25 of 33 strains studied. In conclusion, low-amperage current or 4 h a day of intermittent current delivered using a variety of electrode compositions reduced P. aeruginosa, S. aureus, and S. epidermidis biofilms on a variety of surface materials. The electricidal effect was observed against a majority of bacterial species studied. PMID:26014944

  14. Antibiofilm Activity of Low-Amperage Continuous and Intermittent Direct Electrical Current.

    PubMed

    Schmidt-Malan, Suzannah M; Karau, Melissa J; Cede, Julia; Greenwood-Quaintance, Kerryl E; Brinkman, Cassandra L; Mandrekar, Jayawant N; Patel, Robin

    2015-08-01

    Bacterial biofilms are difficult to treat using available antimicrobial agents, so new antibiofilm strategies are needed. We previously showed that 20, 200, and 2,000 μA of electrical current reduced bacterial biofilms of Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa. Here, we tested continuous direct current at lower amperages, intermittent direct current, and combinations of surface materials (Teflon or titanium) and electrode compositions (stainless steel, graphite, titanium, or platinum) against S. aureus, S. epidermidis, and P. aeruginosa biofilms. In addition, we tested 200 or 2,000 μA for 1 and 4 days against biofilms of 33 strains representing 13 species of microorganisms. The logarithmic reduction factor was used to measure treatment effects. Using continuous current delivery, the lowest active amperage was 2 μA for 1, 4, or 7 days against P. aeruginosa and 5 μA for 7 days against S. epidermidis and S. aureus biofilms. Delivery of 200 μA for 4 h a day over 4 days reduced P. aeruginosa, S. aureus, and S. epidermidis biofilms on Teflon or titanium discs. A reduction of P. aeruginosa, S. aureus, and S. epidermidis biofilms was measured for 23 of 24 combinations of surface materials and electrode compositions tested. Four days of direct current delivery reduced biofilms of 25 of 33 strains studied. In conclusion, low-amperage current or 4 h a day of intermittent current delivered using a variety of electrode compositions reduced P. aeruginosa, S. aureus, and S. epidermidis biofilms on a variety of surface materials. The electricidal effect was observed against a majority of bacterial species studied. PMID:26014944

  15. Multiple-input experimental modal analysis

    NASA Technical Reports Server (NTRS)

    Allemang, R. J.; Brown, D. L.

    1985-01-01

    The development of experimental modal analysis techniques is reviewed. System and excitation assumptions are discussed. The methods examined include the forced normal mode excitation method, the frequency response function method, the damped complex exponential response method, the Ibrahim time domain approach, the polyreference approach, and mathematical input-output model methods. The current trend toward multiple input utilization in the estimation of system parameters is noted.

  16. Lasting modulation of in vitro oscillatory activity with weak direct current stimulation

    PubMed Central

    Bikson, Marom; Parra, Lucas C.

    2014-01-01

    Transcranial direct current stimulation (tDCS) is emerging as a versatile tool to affect brain function. While the acute neurophysiological effects of stimulation are well understood, little is know about the long-term effects. One hypothesis is that stimulation modulates ongoing neural activity, which then translates into lasting effects via physiological plasticity. Here we used carbachol-induced gamma oscillations in hippocampal rat slices to establish whether prolonged constant current stimulation has a lasting effect on endogenous neural activity. During 10 min of stimulation, the power and frequency of gamma oscillations, as well as multiunit activity, were modulated in a polarity specific manner. Remarkably, the effects on power and multiunit activity persisted for more than 10 min after stimulation terminated. Using a computational model we propose that altered synaptic efficacy in excitatory and inhibitory pathways could be the source of these lasting effects. Future experimental studies using this novel in vitro preparation may be able to confirm or refute the proposed hypothesis. PMID:25505103

  17. Are passive red spirals truly passive?. The current star formation activity of optically red disc galaxies

    NASA Astrophysics Data System (ADS)

    Cortese, L.

    2012-07-01

    We used GALEX ultraviolet and WISE 22 μm observations to investigate the current star formation activity of the optically red spirals recently identified as part of the Galaxy Zoo project. These galaxies were accurately selected from the Sloan Digital Sky Survey as pure discs with low or no current star formation activity, representing one of the best optically selected samples of candidate passive spirals. However, we show that these galaxies are not only still forming stars at a significant rate (≳1 M⊙ yr-1) but, more importantly, their star formation activity is not different from that of normal star-forming discs of the same stellar mass (M∗ ≳ 1010.2 M⊙). Indeed, these systems lie on the UV-optical blue sequence, even without any corrections for internal dust attenuation, and they follow the same specific star formation rate vs. stellar mass relation of star-forming galaxies. Our findings clearly show that at high stellar masses, optical colours do not allow to distinguish between actively star-forming and truly quiescent systems.

  18. Biological activity of celecoxib in the bronchial epithelium of current and former smokers.

    PubMed

    Kim, Edward S; Hong, Waun K; Lee, J Jack; Mao, Li; Morice, Rodolfo C; Liu, Diane D; Jimenez, Carlos A; Eapen, Georgie A; Lotan, Reuben; Tang, Ximing; Newman, Robert A; Wistuba, Ignacio I; Kurie, Jonathan M

    2010-02-01

    Non-small cell lung cancer is the primary cause of cancer-related death in Western countries. One important approach taken to address this problem is the development of effective chemoprevention strategies. In this study, we examined whether the cyclooxygenase-2 inhibitor celecoxib, as evidenced by decreased cell proliferation, is biologically active in the bronchial epithelium of current and former smokers. Current or former smokers with at least a 20 pack-year (pack-year = number of packs of cigarettes per day times number of years smoked) smoking history were randomized into one of four treatment arms (3-month intervals of celecoxib then placebo, celecoxib then celecoxib, placebo then celecoxib, or placebo then placebo) and underwent bronchoscopies with biopsies at baseline, 3 months, and 6 months. The 204 patients were primarily (79.4%) current smokers: 81 received either low-dose celecoxib or placebo and 123 received either high-dose celecoxib or placebo. Celecoxib was originally administered orally at 200 mg twice daily and the protocol subsequently increased the dose to 400 mg twice daily. The primary end point was change in Ki-67 labeling (from baseline to 3 months) in bronchial epithelium. No cardiac toxicities were observed in the participants. Although the effect of low-dose treatment was not significant, high-dose celecoxib decreased Ki-67 labeling by 3.85% in former smokers and by 1.10% in current smokers-a significantly greater reduction (P = 0.02) than that seen with placebo after adjusting for metaplasia and smoking status. A 3- to 6-month celecoxib regimen proved safe to administer. Celecoxib (400 mg twice daily) was biologically active in the bronchial epithelium of current and former smokers; additional studies on the efficacy of celecoxib in non-small cell lung cancer chemoprevention may be warranted. PMID:20103722

  19. A Sodium Leak Current Regulates Pacemaker Activity of Adult Central Pattern Generator Neurons in Lymnaea Stagnalis

    PubMed Central

    Lu, Tom Z.; Feng, Zhong-Ping

    2011-01-01

    The resting membrane potential of the pacemaker neurons is one of the essential mechanisms underlying rhythm generation. In this study, we described the biophysical properties of an uncharacterized channel (U-type channel) and investigated the role of the channel in the rhythmic activity of a respiratory pacemaker neuron and the respiratory behaviour in adult freshwater snail Lymnaea stagnalis. Our results show that the channel conducts an inward leak current carried by Na+ (ILeak-Na). The ILeak-Na contributed to the resting membrane potential and was required for maintaining rhythmic action potential bursting activity of the identified pacemaker RPeD1 neurons. Partial knockdown of the U-type channel suppressed the aerial respiratory behaviour of the adult snail in vivo. These findings identified the Na+ leak conductance via the U-type channel, likely a NALCN-like channel, as one of the fundamental mechanisms regulating rhythm activity of pacemaker neurons and respiratory behaviour in adult animals. PMID:21526173

  20. Effect of Heat Input on Microstructure Evolution and Mechanical Properties in the Weld Heat-Affected Zone of 9Cr-2W-VTa Reduced Activation Ferritic-Martensitic Steel for Fusion Reactor

    NASA Astrophysics Data System (ADS)

    Moon, Joonoh; Lee, Chang-Hoon; Lee, Tae-Ho; Kim, Hyoung Chan

    2015-01-01

    The phase transformation and mechanical properties in the weld heat-affected zone (HAZ) of a reduced activation ferritic/martensitic steel were explored. The samples for HAZs were prepared using a Gleeble simulator at different heat inputs. The base steel consisted of tempered martensite and carbides through quenching and tempering treatment, whereas the HAZs consisted of martensite, δ-ferrite, and a small volume of autotempered martensite. The prior austenite grain size, lath width of martensite, and δ-ferrite fraction in the HAZs increased with increase in the heat input. The mechanical properties were evaluated using Vickers hardness and Charpy V-notch impact test. The Vickers hardness in the HAZs was higher than that in the base steel but did not change noticeably with increase in the heat input. The HAZs showed poor impact property due to the formation of martensite and δ-ferrite as compared to the base steel. In addition, the impact property of the HAZs deteriorated more with the increase in the heat input. Post weld heat treatment contributed to improve the impact property of the HAZs through the formation of tempered martensite, but the impact property of the HAZs remained lower than that of base steel.

  1. Network burst activity in hippocampal neuronal cultures: the role of synaptic and intrinsic currents.

    PubMed

    Suresh, Jyothsna; Radojicic, Mihailo; Pesce, Lorenzo L; Bhansali, Anita; Wang, Janice; Tryba, Andrew K; Marks, Jeremy D; van Drongelen, Wim

    2016-06-01

    The goal of this work was to define the contributions of intrinsic and synaptic mechanisms toward spontaneous network-wide bursting activity, observed in dissociated rat hippocampal cell cultures. This network behavior is typically characterized by short-duration bursts, separated by order of magnitude longer interburst intervals. We hypothesize that while short-timescale synaptic processes modulate spectro-temporal intraburst properties and network-wide burst propagation, much longer timescales of intrinsic membrane properties such as persistent sodium (Nap) currents govern burst onset during interburst intervals. To test this, we used synaptic receptor antagonists picrotoxin, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), and 3-(2-carboxypiperazine-4-yl)propyl-1-phosphonate (CPP) to selectively block GABAA, AMPA, and NMDA receptors and riluzole to selectively block Nap channels. We systematically compared intracellular activity (recorded with patch clamp) and network activity (recorded with multielectrode arrays) in eight different synaptic connectivity conditions: GABAA + NMDA + AMPA, NMDA + AMPA, GABAA + AMPA, GABAA + NMDA, AMPA, NMDA, GABAA, and all receptors blocked. Furthermore, we used mixed-effects modeling to quantify the aforementioned independent and interactive synaptic receptor contributions toward spectro-temporal burst properties including intraburst spike rate, burst activity index, burst duration, power in the local field potential, network connectivity, and transmission delays. We found that blocking intrinsic Nap currents completely abolished bursting activity, demonstrating their critical role in burst onset within the network. On the other hand, blocking different combinations of synaptic receptors revealed that spectro-temporal burst properties are uniquely associated with synaptic functionality and that excitatory connectivity is necessary for the presence of network-wide bursting. In addition to confirming the critical contribution of direct

  2. Calcium-activated chloride current expression in axotomized sensory neurons: what for?

    PubMed Central

    Boudes, Mathieu; Scamps, Frédérique

    2012-01-01

    Calcium-activated chloride currents (CaCCs) are activated by an increase in intracellular calcium concentration. Peripheral nerve injury induces the expression of CaCCs in a subset of adult sensory neurons in primary culture including mechano- and proprioceptors, though not nociceptors. Functional screenings of potential candidate genes established that Best1 is a molecular determinant for CaCC expression among axotomized sensory neurons, while Tmem16a is acutely activated by inflammatory mediators in nociceptors. In nociceptors, such CaCCs are preferentially activated under receptor-induced calcium mobilization contributing to cell excitability and pain. In axotomized mechano- and proprioceptors, CaCC activation does not promote electrical activity and prevents firing, a finding consistent with electrical silencing for growth competence of adult sensory neurons. In favor of a role in the process of neurite growth, CaCC expression is temporally correlated to neurons displaying a regenerative mode of growth. This perspective focuses on the molecular identity and role of CaCC in axotomized sensory neurons and the future directions to decipher the cellular mechanisms regulating CaCC during neurite (re)growth. PMID:22461766

  3. Activation of ganglion cells in wild-type and rd1 mouse retinas with monophasic and biphasic current pulses

    NASA Astrophysics Data System (ADS)

    Jensen, Ralph J.; Rizzo, Joseph F. III

    2009-06-01

    We and other research groups are designing an electronic retinal prosthesis to provide vision for patients who are blind due to photoreceptor degeneration. In this study, we examined the effect of stimulus waveform on the amount of current needed to activate retinal ganglion cells (RGCs) when the retinal neural network is stimulated. Isolated retinas of wild-type and rd1 mice were stimulated with cathodal and anodal monophasic current pulses of 1 ms duration and symmetric biphasic current pulses (1 ms per phase) delivered through an electrode that was located subretinally. For both wild-type and rd1 mouse retinas, cathodal current pulses were least effective in activating most RGCs. The median threshold current for a cathodal current pulse was 2.0-4.4 fold higher than the median threshold current for either an anodal or a biphasic current pulse. In wild-type mouse retinas, the median threshold current for activating RGCs with anodal current pulses was 23% lower than that with biphasic current pulses. In rd1 mouse retinas, the median threshold currents for anodal and biphasic current pulses were about the same. However, the variance in thresholds of rd1 RGCs for biphasic pulse stimulation was much smaller than for anodal pulse stimulation. Thus, a symmetric biphasic current pulse may be the best stimulus for activating the greatest number of RGCs in retinas devoid of photoreceptors.

  4. The activity intensities reached when playing active tennis gaming relative to sedentary gaming, tennis game-play, and current activity recommendations in young adults.

    PubMed

    Scanlan, Aaron T; Arkinstall, Hayley; Dalbo, Vincent J; Humphries, Brendan J; Jennings, Cameron T; Kingsley, Michael I C

    2013-09-01

    Although active gaming is popular and can increase energy expenditure in young adults, its efficacy as a prescriptive exercise tool is not well understood. This study aimed to: (a) compare the activity intensities experienced by young adults while playing active tennis gaming with conventional sedentary gaming, tennis game-play, and current activity recommendations for health; and (b) identify changes in activity intensities across playing time. After habitualization, 10 active young adults (age: 20.2 ± 0.4 years; stature: 1.74 ± 0.03 m; body mass: 67.7 ± 3.3 kg) completed 3 experimental trials (sedentary gaming, active tennis gaming, and tennis game-play) on separate days in a randomized order. Heart rate (HR) and metabolic equivalents (METs) were averaged across 5 minutes and 10 minutes intervals, and the entire 20 minutes bout within each condition. Active gaming produced greater intensities across 5-10, 10-15, and 15-20 minutes time intervals compared with sedentary gaming (p < 0.01). Tennis game-play elicited greater HR (67 ± 5% HR(max)) and METs (5.0 ± 0.2) responses than both sedentary (40 ± 2% HR(max), 1.1 ± 0.1 METs) and active gaming (45 ± 2% HR(max), 1.4 ± 0.1 METs) (p < 0.001). Only tennis game-play produced activity intensities meeting current recommendations for health benefit. Lower HR intensities were reached across 0-5 minutes than during later time intervals during active gaming (6%) and tennis game-play (9%) (p < 0.01). Activity intensities elicited by active gaming were greater than sedentary gaming but less than tennis game-play and insufficient to contribute toward promoting and maintaining good health in young adults. These data suggest that active tennis gaming should not be recommended by exercise professionals as a substitute for actual sports participation in young adults. PMID:23238089

  5. Ca2+-activated K+ currents regulate odor adaptation by modulating spike encoding of olfactory receptor cells.

    PubMed

    Kawai, Fusao

    2002-04-01

    The olfactory system is thought to accomplish odor adaptation through the ciliary transduction machinery in olfactory receptor cells (ORCs). However, ORCs that have lost their cilia can exhibit spike frequency accommodation in which the action potential frequency decreases with time despite a steady depolarizing stimulus. This raises the possibility that somatic ionic channels in ORCs might serve for odor adaptation at the level of spike encoding, because spiking responses in ORCs encode the odor information. Here I investigate the adaptational mechanism at the somatic membrane using conventional and dynamic patch-clamp recording techniques, which enable the ciliary mechanism to be bypassed. A conditioning stimulus with an odorant-induced current markedly shifted the response range of action potentials induced by the same test stimulus to higher concentrations of the odorant, indicating odor adaptation. This effect was inhibited by charybdotoxin and iberiotoxin, Ca2+-activated K+ channel blockers, suggesting that somatic Ca2+-activated K+ currents regulate odor adaptation by modulating spike encoding. I conclude that not only the ciliary machinery but also the somatic membrane currents are crucial to odor adaptation. PMID:11916858

  6. Extraction of activation energies from temperature dependence of dark currents of SiPM

    NASA Astrophysics Data System (ADS)

    Engelmann, E.; Vinogradov, S.; Popova, E.; Wiest, F.; Iskra, P.; Gebauer, W.; Loebner, S.; Ganka, T.; Dietzinger, C.; Fojt, R.; Hansch, W.

    2016-02-01

    Despite several advantages of Silicon Photomultipliers (SiPM) over Photomultiplier Tubes (PMT) like the increased photon detection efficiency (PDE), the compact design and the insensitivity to magnetic fields, the dark count rate (DCR) of SiPM is still a large drawback. Decreasing of the SiPM dark count rate has become a modern task, which could lead to an enormous enhancement of the application range of this promising photo-detector. The main goal of this work is to gain initial information on the dark generation and identify the dominating contributions to dark currents. The chosen approach to fulfill this task is to extract characteristic activation energies of the contributing mechanisms from temperature dependent investigations of dark currents and DCR. Since conventional methods are not suited for a precise analysis of activation energies, a new method has to be developed. In this paper, first steps towards the development of a reliable method for the analysis of dark currents and dark events are presented.

  7. Active current sheets and hot flow anomalies in Mercury's bow shock

    NASA Astrophysics Data System (ADS)

    Uritsky, V. M.; Slavin, J. A.; Boardsen, S. A.; Sundberg, T.; Raines, J. M.; Anderson, B. J.; Korth, H.

    2012-12-01

    Hot flow anomalies (HFAs) represent a subset of heliospheric current sheets interacting with planetary bow shocks. They are typically formed when the normal component of the motional (convective) electric field is directed toward the embedded current sheet on at least one side. The core region of an HFA contains hot and highly deflected ion flows and rather low and turbulent magnetic field. In this talk, we report the first observations of HFA-like events at Mercury. Using the data from the orbital phase of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, we identify a representative ensemble of active current sheets magnetically connected to Mercury's bow shock. We show that some of these events exhibit unambiguous signatures of HFAs similar to those observed at other planets, and present their key physical characteristics. Our analysis suggests that Mercury's bow shock does not only mediate the flow of supersonic solar wind plasma but also provides conditions for local particle acceleration and heating as predicted by previous numerical simulations. Together with earlier studies of HFA activity at Earth, Venus, and Saturn, our results confirm that hot flow anomalies could be a common property of planetary bow shocks.

  8. Calcium-activated chloride currents prolongs the duration of contractions in pregnant rat myometrial tissue.

    PubMed

    Young, Roger C; Bemis, Adam

    2009-08-01

    We investigated the importance of pharmacologically blocking calcium-activated chloride (I(Cl(Ca))) and L-type calcium currents on isometric contractions of strips of D21 pregnant rat myometrial tissue, while simultaneously measuring the electrical activity of the tissue strips with extracellular contact electrodes. When measured with contact electrodes, the duration of the spiking activity directly reflects the duration of the tissue-level plateau potential. We correlated the number of spikes, durations of spiking activity, and the spiking frequencies with changes of the area under the force curves as a function of exposure to low doses of anthracene-9-carboxylate (9-AC, a non-specific Cl channel blocker), chlorotoxin (a specific I(Cl(Ca)) blocker) and nifedipine (an L-type calcium channel blocker). The area under the force curve was measured only during spiking electrical activity, thereby separating pharmacological effects on tissue relaxation from those that modulate force production. Blocking chloride channels reduced impulse, shortened the duration of spiking activity, and reduced the number of spikes generated in each contraction. This was observed without a change in the frequency of spike production or a reduction of peak force. Nifedipine reduced impulse, shortened the duration of spiking activity, and reduced the number of spikes. In contrast to chloride channel blockade, nifedipine reduced maximum spike frequency and peak force. Taken together, our data suggest that blocking L-type calcium channels reduces impulse directly by reducing peak force, and indirectly by reducing activation of I(Cl(Ca)) , which shortens the duration of the contraction. PMID:19380901

  9. Ultrasound Current Source Density Imaging of the Cardiac Activation Wave Using a Clinical Cardiac Catheter

    PubMed Central

    Qin, Yexian; Li, Qian; Ingram, Pier; Barber, Christy; Liu, Zhonglin

    2015-01-01

    Ultrasound current source density imaging (UCSDI), based on the acoustoelectric (AE) effect, is a noninvasive method for mapping electrical current in 4-D (space + time). This technique potentially overcomes limitations with conventional electrical mapping procedures typically used during treatment of sustained arrhythmias. However, the weak AE signal associated with the electrocardiogram is a major challenge for advancing this technology. In this study, we examined the effects of the electrode configuration and ultrasound frequency on the magnitude of the AE signal and quality of UCSDI using a rabbit Langendorff heart preparation. The AE signal was much stronger at 0.5 MHz (2.99 μV/MPa) than 1.0 MHz (0.42 μV/MPa). Also, a clinical lasso catheter placed on the epicardium exhibited excellent sensitivity without penetrating the tissue. We also present, for the first time, 3-D cardiac activation maps of the live rabbit heart using only one pair of recording electrodes. Activation maps were used to calculate the cardiac conduction velocity for atrial (1.31 m/s) and apical (0.67 m/s) pacing. This study demonstrated that UCSDI is potentially capable of real-time 3-D cardiac activation wave mapping, which would greatly facilitate ablation procedures for treatment of arrhythmias. PMID:25122512

  10. New hybrid active power filter for harmonic current suppression and reactive power compensation

    NASA Astrophysics Data System (ADS)

    Biricik, Samet; Cemal Ozerdem, Ozgur; Redif, Soydan; Sezai Dincer, Mustafa

    2016-08-01

    In the case of undistorted and balanced grid voltages, low ratio shunt active power filters (APFs) can give unity power factors and achieve current harmonic cancellation. However, this is not possible when source voltages are distorted and unbalanced. In this study, the cost-effective hybrid active power filter (HAPF) topology for satisfying the requirements of harmonic current suppression and non-active power compensation for industry is presented. An effective strategy is developed to observe the effect of the placement of power capacitors and LC filters with the shunt APF. A new method for alleviating the negative effects of a nonideal grid voltage is proposed that uses a self-tuning filter algorithm with instantaneous reactive power theory. The real-time control of the studied system was achieved with a field-programmable gate array (FPGA) architecture, which was developed using the OPAL-RT system. The performance result of the proposed HAPF system is tested and presented under nonideal supply voltage conditions.

  11. Hypermnesia using auditory input.

    PubMed

    Allen, J

    1992-07-01

    The author investigated whether hypermnesia would occur with auditory input. In addition, the author examined the effects of subjects' knowledge that they would later be asked to recall the stimuli. Two groups of 26 subjects each were given three successive recall trials after they listened to an audiotape of 59 high-imagery nouns. The subjects in the uninformed group were not told that they would later be asked to remember the words; those in the informed group were. Hypermnesia was evident, but only in the uninformed group. PMID:1447564

  12. Input distributions for VISA

    SciTech Connect

    Liebetrau, A.M.

    1983-10-01

    Work is underway at Pacific Northwest Laboratory (PNL) to improve the probabilistic analysis used to model pressurized thermal shock (PTS) incidents in reactor pressure vessels, and, further, to incorporate these improvements into the existing Vessel Integrity Simulation Analysis (VISA) code. Two topics related to work on input distributions in VISA are discussed in this paper. The first involves the treatment of flaw size distributions and the second concerns errors in the parameters in the (Guthrie) equation which is used to compute ..delta..RT/sub NDT/, the shift in reference temperature for nil ductility transition.

  13. Density-matrix renormalization-group study of current and activity fluctuations near nonequilibrium phase transitions.

    PubMed

    Gorissen, Mieke; Hooyberghs, Jef; Vanderzande, Carlo

    2009-02-01

    Cumulants of a fluctuating current can be obtained from a free-energy-like generating function, which for Markov processes equals the largest eigenvalue of a generalized generator. We determine this eigenvalue with the density-matrix renormalization group for stochastic systems. We calculate the variance of the current in the different phases, and at the phase transitions, of the totally asymmetric exclusion process. Our results can be described in the terms of a scaling ansatz that involves the dynamical exponent z . We also calculate the generating function of the dynamical activity (total number of configuration changes) near the absorbing-state transition of the contact process. Its scaling properties can be expressed in terms of known critical exponents. PMID:19391693

  14. Instantaneous Active and Nonactive Power Control of Distributed Energy Resources with Current Limiter

    SciTech Connect

    Xu, Yan; Li, Huijuan; Rizy, D Tom; Li, Fangxing; Kueck, John D

    2010-01-01

    Abstract -- Distributed energy resources (DER) with a power electronics inverter interface can provide both active power and nonactive power simultaneously and independently. A decoupled control algorithm of active power and nonactive power is developed based on the instantaneous active power and nonactive power theory. A current limiter is combined to the control algorithm, and it ensures that the inverter is not overloaded. During the normal system operation, the active power has higher priority over the nonactive power so that the energy from a DER can be fully transferred to the grid. Within the inverter s capability, nonactive power is provided to the grid as required. With this control algorithm, the inverter s capabilities are taken full advantage at all times, both in terms of functionality as well as making use of its full KVA rating. Through the algorithm, the inverter s active power and nonactive power are controlled directly, simultaneously, and independently. Several experimental results fully demonstrate the validity and effectiveness of this new control algorithm. As evidenced by the fast dynamic response that results, a DER system with the control algorithm can provide full services to the grid in both steady state and during transient events.

  15. Current research activities at the NASA-sponsored Illinois Computing Laboratory of Aerospace Systems and Software

    NASA Technical Reports Server (NTRS)

    Smith, Kathryn A.

    1994-01-01

    The Illinois Computing Laboratory of Aerospace Systems and Software (ICLASS) was established to: (1) pursue research in the areas of aerospace computing systems, software and applications of critical importance to NASA, and (2) to develop and maintain close contacts between researchers at ICLASS and at various NASA centers to stimulate interaction and cooperation, and facilitate technology transfer. Current ICLASS activities are in the areas of parallel architectures and algorithms, reliable and fault tolerant computing, real time systems, distributed systems, software engineering and artificial intelligence.

  16. Current Suicidal Ideation among Treatment-Engaged Active Duty Soldiers and Marines

    PubMed Central

    Zimmerman, Lindsey; Villatte, Jennifer L.; Kerbrat, Amanda H.; Atkins, David C.; Flaster, Aaron; Comtois, Kate A.

    2015-01-01

    We examined suicidal ideation among 399 active duty Soldiers and Marines engaged in mental health treatment. Using a generalized linear model controlling for demographic and military factors, depression, and positive traumatic brain injury screen, we confirmed our hypothesis that self-report measures of current PTSD symptoms uniquely predicted suicidal ideation. The association between PTSD severity and suicidal ideation was moderated by gender with women at higher risk as PTSD severity increased. Female Soldiers and Marines with high levels of PTSD should receive additional monitoring and intervention. Self-report measures may aid with risk assessment and identify symptom-related distress associated with suicide risk. PMID:27170848

  17. Potassium currents inhibition by gambierol analogs prevents human T lymphocyte activation.

    PubMed

    Rubiolo, J A; Vale, C; Martín, V; Fuwa, H; Sasaki, M; Botana, L M

    2015-07-01

    Gambierol is a marine polycyclic ether toxin, produced along with ciguatoxin congeners by the dinoflagellate Gambierdiscus toxicus. We have recently reported that two truncated skeletal analogs of gambierol comprising the EFGH- and BCDEFGH-rings of the parent compound showed similar potency to gambierol on voltage-gated potassium channels (Kv) inhibition in neurons. Gambierol and its truncated analogs share the main crucial elements for biological activity, which are the C28=C29 double bond within the H-ring and the unsaturated side chain. Since Kv channels are critical for the regulation of calcium signaling, proliferation, secretion and migration in human T lymphocytes, we evaluated the activity of both the tetracyclic and heptacyclic analogs of gambierol on potassium currents in resting T lymphocyte and their effects on interleukin-2 (IL-2) release and gene expression in activated T lymphocytes. The results presented in this work clearly demonstrate that both truncated analogs of gambierol inhibit Kv channels present in resting T lymphocytes (Kv1.3) and prevented lymphocyte activation by concanavalin A. The main effects of the heptacyclic and tetracyclic analogs of gambierol in human T cells are: (1) inhibition of potassium channels in resting and concanavalin-activated T cells in the nanomolar range, (2) inhibition of IL-2 release from concanavalin-activated T cells and (3) negatively affect the expression of genes involved in cell proliferation and immune response observed in concanavalin-activated lymphocytes. These results together with the lack of toxicity in this cellular model, indicates that both analogs of gambierol have additional potential for the development of therapeutic tools in autoimmune diseases. PMID:25155189

  18. Activation of CFTR chloride current by nitric oxide in human T lymphocytes.

    PubMed Central

    Dong, Y J; Chao, A C; Kouyama, K; Hsu, Y P; Bocian, R C; Moss, R B; Gardner, P

    1995-01-01

    Nitric oxide, which is produced by cytokine-activated mononuclear cells, is thought to play an important role in inflammation and immunity. While the function of nitric oxide as a direct cytotoxic effector molecule is well established, its function as a transducer molecule in immune cells is not. By use of whole-cell patch clamp recordings, we show that nitric oxide activates cystic fibrosis transmembrane conductance regulator CI- currents in normal human cloned T cells by a cGMP-dependent mechanism. This pathway is defective in cystic fibrosis-derived human cloned T cells. These findings not only delineate a novel transduction mechanism for nitric oxide but also support the hypothesis that an intrinsic immune defect may exist in cystic fibrosis. PMID:7540975

  19. Strategic Classification and Examination of the Development of Current Airline Alliance Activities

    NASA Technical Reports Server (NTRS)

    Wang, Zhi H.; Evans, Michael

    2002-01-01

    Previous research argues that despite the fact that strategic alliances have become an important feature of the world airline industry, little rigorous analysis has been done on the effects of these alliances. This is partially because there is a lack of precise definitions to specify different types of airline alliances in the literature. This research identifies several categories of airline alliances through a strategic classification of the current alliance activities involving the major airlines for the period 1989 to 1999. The classification enables this research to examine how strategic alliance activities are evolving, particularly to compare how airlines in North America, the European Union and the Asia Pacific region have committed to different alliances. Findings show that there is a significant difference between the number and scope of alliances adopted in the three aviation markets. These findings facilitate research to further analyse the impact of market liberalization on various formations of strategic airline alliances.

  20. Current topics in active and intelligent food packaging for preservation of fresh foods.

    PubMed

    Lee, Seung Yuan; Lee, Seung Jae; Choi, Dong Soo; Hur, Sun Jin

    2015-11-01

    The purpose of this review is to provide an overview of current packaging systems, e.g. active packaging and intelligent packaging, for various foods. Active packaging, such as modified atmosphere packaging (MAP), extends the shelf life of fresh produce, provides a high-quality product, reduces economic losses, including those caused by delay of ripening, and improves appearance. However, in active packaging, several variables must be considered, such as temperature control and different gas formulations with different product types and microorganisms. Active packaging refers to the incorporation of additive agents into packaging materials with the purpose of maintaining or extending food product quality and shelf life. Intelligent packaging is emerging as a potential advantage in food processing and is an especially useful tool for tracking product information and monitoring product conditions. Moreover, intelligent packaging facilitates data access and information exchange by altering conditions inside or outside the packaging and product. In spite of these advantages, few of these packaging systems are commercialized because of high cost, strict safety and hygiene regulations or limited consumer acceptance. Therefore more research is needed to develop cheaper, more easily applicable and effective packaging systems for various foods. PMID:25892577

  1. Revealing the activation pathway for TMEM16A chloride channels from macroscopic currents and kinetic models.

    PubMed

    Contreras-Vite, Juan A; Cruz-Rangel, Silvia; De Jesús-Pérez, José J; Figueroa, Iván A Aréchiga; Rodríguez-Menchaca, Aldo A; Pérez-Cornejo, Patricia; Hartzell, H Criss; Arreola, Jorge

    2016-07-01

    TMEM16A (ANO1), the pore-forming subunit of calcium-activated chloride channels, regulates several physiological and pathophysiological processes such as smooth muscle contraction, cardiac and neuronal excitability, salivary secretion, tumour growth and cancer progression. Gating of TMEM16A is complex because it involves the interplay between increases in intracellular calcium concentration ([Ca(2+)]i), membrane depolarization, extracellular Cl(-) or permeant anions and intracellular protons. Our goal here was to understand how these variables regulate TMEM16A gating and to explain four observations. (a) TMEM16A is activated by voltage in the absence of intracellular Ca(2+). (b) The Cl(-) conductance is decreased after reducing extracellular Cl(-) concentration ([Cl(-)]o). (c) ICl is regulated by physiological concentrations of [Cl(-)]o. (d) In cells dialyzed with 0.2 μM [Ca(2+)]i, Cl(-) has a bimodal effect: at [Cl(-)]o <30 mM TMEM16A current activates with a monoexponential time course, but above 30 mM, [Cl(-)]o ICl activation displays fast and slow kinetics. To explain the contribution of Vm, Ca(2+) and Cl(-) to gating, we developed a 12-state Markov chain model. This model explains TMEM16A activation as a sequential, direct, and Vm-dependent binding of two Ca(2+) ions coupled to a Vm-dependent binding of an external Cl(-) ion, with Vm-dependent transitions between states. Our model predicts that extracellular Cl(-) does not alter the apparent Ca(2+) affinity of TMEM16A, which we corroborated experimentally. Rather, extracellular Cl(-) acts by stabilizing the open configuration induced by Ca(2+) and by contributing to the Vm dependence of activation. PMID:27138167

  2. A hyperpolarization-activated inward current alters swim frequency of the pteropod mollusk Clione limacina.

    PubMed

    Pirtle, Thomas J; Willingham, Kyle; Satterlie, Richard A

    2010-12-01

    The pteropod mollusk, Clione limacina, exhibits behaviorally relevant swim speed changes that occur within the context of the animal's ecology. Modulation of C. limacina swimming speed involves changes that occur at the network and cellular levels. Intracellular recordings from interneurons of the swim central pattern generator show the presence of a sag potential that is indicative of the hyperpolarization-activated inward current (I(h)). Here we provide evidence that I(h) in primary swim interneurons plays a role in C. limacina swimming speed control and may be a modulatory target. Recordings from central pattern generator swim interneurons show that hyperpolarizing current injection produces a sag potential that lasts for the duration of the hyperpolarization, a characteristic of cells possessing I(h). Following the hyperpolarizing current injection, swim interneurons also exhibit postinhibitory rebound (PIR). Serotonin enhances the sag potential of C. limacina swim interneurons while the I(h) blocker, ZD7288, reduces the sag potential. Furthermore, a negative correlation was found between the amplitude of the sag potential and latency to PIR. Because latency to PIR was previously shown to influence swimming speed, we hypothesize that I(h) has an effect on swimming speed. The I(h) blocker, ZD7288, suppresses swimming in C. limacina and inhibits serotonin-induced acceleration, evidence that supports our hypothesis. PMID:20696266

  3. Effects of Current Velocity, Particle Size, and Substrate Heterogeneity on Crayfish (Orconectes propinquus) Activity

    NASA Astrophysics Data System (ADS)

    Clark, J. M.; Kershner, M. W.

    2005-05-01

    The use of flow refugia (e.g., substrate) by lotic invertebrates often increases their likelihood of survival during flood events. Movement to potential refugia becomes risky as velocities increase, and the range of velocities that benthic invertebrates can withstand is variable. In this study, activity time and slip velocities of small [carapace length (CL)=10-20 mm] and large (CL=20-30 mm) Orconectes propinquus were measured in an artificial flume across ranges of current velocity and substrate heterogeneity. Particle sizes included small pebbles (16-32 mm), large pebbles (32-64 mm), and small cobble (64-128 mm). Water velocity was increased by 0.1 m/s increments from 0.1-1.5 m/s at 5-minute intervals or until the crayfish was dislodged from the substrate. As current velocity increased, the probability of slipping increased for all crayfish. Regardless of the degree of substrate heterogeneity, small crayfish held their position at higher velocities than large crayfish and were also less active. Slip rates were generally lower for both sizes as substrate heterogeneity increased. Essentially, the availability and probability of finding refugia increased with increased habitat heterogeneity and allowed crayfish to avoid being swept into the drift.

  4. Active current sheets and candidate hot flow anomalies upstream of Mercury's bow shock

    NASA Astrophysics Data System (ADS)

    Uritsky, V. M.; Slavin, J. A.; Boardsen, S. A.; Sundberg, T.; Raines, J. M.; Gershman, D. J.; Collinson, G.; Sibeck, D.; Khazanov, G. V.; Anderson, B. J.; Korth, H.

    2014-02-01

    Hot flow anomalies (HFAs) represent a subset of solar wind discontinuities interacting with collisionless bow shocks. They are typically formed when the normal component of the motional (convective) electric field points toward the embedded current sheet on at least one of its sides. The core region of an HFA contains hot and highly deflected ion flows and rather low and turbulent magnetic field. In this paper, we report observations of possible HFA-like events at Mercury identified over a course of two planetary years. Using data from the orbital phase of the MESSENGER mission, we identify a representative ensemble of active current sheets magnetically connected to Mercury's bow shock. We show that some of these events exhibit magnetic and particle signatures of HFAs similar to those observed at other planets, and present their key physical characteristics. Our analysis suggests that Mercury's bow shock does not only mediate the flow of supersonic solar wind plasma but also provides conditions for local particle acceleration and heating as predicted by previous numerical simulations. Together with earlier observations of HFA activity at Earth, Venus, Mars, and Saturn, our results confirm that hot flow anomalies could be a common property of planetary bow shocks and show that the characteristic size of these events is controlled by the bow shock standoff distance and/or local solar wind conditions.

  5. Actions of arginine polyamine on voltage and ligand-activated whole cell currents recorded from cultured neurones.

    PubMed Central

    Scott, R. H.; Sweeney, M. I.; Kobrinsky, E. M.; Pearson, H. A.; Timms, G. H.; Pullar, I. A.; Wedley, S.; Dolphin, A. C.

    1992-01-01

    1. Toxins from invertebrates have proved useful tools for investigation of the properties of ion channels. In this study we describe the actions of arginine polyamine which is believed to be a close analogue of FTX, a polyamine isolated from the American funnel web spider, Agelenopsis aperta. 2. Voltage-activated Ca2+ currents and Ca(2+)-dependent Cl- currents recorded from rat cultured dorsal root ganglion neurones were reversibly inhibited by arginine polyamine (AP; 0.001 to 100 microM). Low voltage-activated T-type Ca2+ currents were significantly more sensitive to AP than high voltage-activated Ca2+ currents. The IC50 values for the actions of AP on low and high voltage-activated Ca2+ currents were 10 nM and 3 microM respectively. AP was equally effective in inhibiting high voltage-activated currents carried by Ba2+, Sr2+ or Ca2+. However, AP-induced inhibition of Ca2+ currents was attenuated by increasing the extracellular Ca2+ concentration from 2 mM to 10 mM. 3. The actions of AP on a Ca(2+)-independent K+ current were more complex, 1 microM AP enhanced this current but 10 microM AP had a dual action, initially enhancing but then inhibiting the K+ current. 4. gamma-Aminobutyric acid-activated Cl- currents were also reversibly inhibited by 1 to 10 microM AP. In contrast N-methyl-D-aspartate currents recorded from rat cultured cerebellar neurones were greatly enhanced by 10 microM AP. 5. We conclude that at a concentration of 10 nM, AP is a selective inhibitor of low threshold T-type voltage-activated Ca2+ currents.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1380382

  6. Arctic science input wanted

    NASA Astrophysics Data System (ADS)

    The Arctic Research and Policy Act (Eos, June 26, 1984, p. 412) was signed into law by President Ronald Reagan this past July. One of its objectives is to develop a 5-year research plan for the Arctic. A request for input to this plan is being issued this week to nearly 500 people in science, engineering, and industry.To promote Arctic research and to recommend research policy in the Arctic, the new law establishes a five-member Arctic Research Commission, to be appointed by the President, and establishes an Interagency Arctic Research Policy Committee, to be composed of representatives from nearly a dozen agencies having interests in the region. The commission will make policy recommendations, and the interagency committee will implement those recommendations. The National Science Foundation (NSF) has been designated as the lead agency of the interagency committee.

  7. Electric Current Activated Combustion Synthesis and Chemical Ovens Under Terrestrial and Reduced Gravity Conditions

    NASA Technical Reports Server (NTRS)

    Unuvar, C.; Fredrick, D.; Anselmi-Tamburini, U.; Manerbino, A.; Guigne, J. Y.; Munir, Z. A.; Shaw, B. D.

    2004-01-01

    Combustion synthesis (CS) generally involves mixing reactants together (e.g., metal powders) and igniting the mixture. Typically, a reaction wave will pass through the sample. In field activated combustion synthesis (FACS), the addition of an electric field has a marked effect on the dynamics of wave propagation and on the nature, composition, and homogeneity of the product as well as capillary flow, mass-transport in porous media, and Marangoni flows, which are influenced by gravity. The objective is to understand the role of an electric field in CS reactions under conditions where gravity-related effects are suppressed or altered. The systems being studied are Ti+Al and Ti+3Al. Two different ignition orientations have been used to observe effects of gravity when one of the reactants becomes molten. This consequentially influences the position and concentration of the electric current, which in turn influences the entire process. Experiments have also been performed in microgravity conditions. This process has been named Microgravity Field Activated Combustion Synthesis (MFACS). Effects of gravity have been demonstrated, where the reaction wave temperature and velocity demonstrate considerable differences besides the changes of combustion mechanisms with the different high currents applied. Also the threshold for the formation of a stable reaction wave is increased under zero gravity conditions. Electric current was also utilized with a chemical oven technique, where inserts of aluminum with minute amounts of tungsten and tantalum were used to allow observation of effects of settling of the higher density solid particles in liquid aluminum at the present temperature profile and wave velocity of the reaction.

  8. Low-voltage constant- g m rail-to-rail CMOS operational amplifier input stage

    NASA Astrophysics Data System (ADS)

    Lu, Yan; Yao, Ruo He

    2008-06-01

    This paper presents a rail-to-rail constant-gm operational amplifier input stage. The proposed circuit changes the tail current of the input differential pairs dynamically for a constant-gm by using dummy input differential pairs. The problem which causes total gm variation is input pairs and dummy input pairs can not take effect at the same time with the common-mode input voltage changes, because the tail current transistor of the input pairs are in triode region when the input pairs are turned off, the dummy input pairs will enter subthreshold region from cut-off region before the input pairs when common-mode voltage changes. The effect of this problem is more obviously in low supply voltage design. To solve this problem, compensate current sources is added to the tail current transistors of each dummy input differential pairs for lower gm variation. The gm of this Op Amp's input stage varies around ±2%.

  9. Calcium current activation kinetics in isolated pyramidal neurones of the Ca1 region of the mature guinea-pig hippocampus.

    PubMed

    Kay, A R; Wong, R K

    1987-11-01

    1. Neurones were isolated from the CA1 region of the guinea-pig hippocampus and subjected to the whole-cell mode of voltage clamping, to determine the kinetics of voltage-gated Ca2+ channel activation. 2. Isolated neurones had an abbreviated morphology, having lost most of the distal dendritic tree during the isolation procedure. The electrical compactness of the cells facilitates voltage clamp analysis. 3. Block of sodium and potassium currents revealed a persistent current activated on depolarization above -40 mV, which inactivated slowly when the intracellular medium contained EGTA. The current was blocked by Co2+ and Cd2+, augmented by increases in Ca2+ and could be carried by Ba2+, suggesting that the current is borne by Ca2+. 4. Steady-state activation of the Ca2+ current was found to be well described by the Boltzman equation raised to the second power. 5. The open channel's current-voltage (I-V) relationship rectified in the inward direction and was consistent with the constant-field equation. 6. The kinetics of Ca2+ current onset followed m2 kinetics throughout the range of its activation. Tail current kinetics were in accord with this model. A detailed Hodgkin-Huxley model was derived, defining the activation of this current. 7. The kinetics of the currents observed in this regionally and morphologically defined class of neurones were consistent with the existence of a single kinetic class of channels. PMID:2451732

  10. Distinct modifications of convergent excitatory and inhibitory inputs in developing olfactory circuits.

    PubMed

    Ma, T-F; Chen, P-H; Hu, X-Q; Zhao, X-L; Tian, T; Lu, W

    2014-06-01

    The interaction between excitatory and inhibitory inputs is critical to neuronal signal processing. However, little is known about this fundamental property, largely due to the inability to clearly isolate the respective inputs. Here we took advantage of the characteristic stereotypical architecture of synaptic connections in the main olfactory bulb, which enabled us to entirely separate excitatory and inhibitory inputs. Using paired stimulation of two glomeruli located apart at different intensities, we separately elicited excitatory and inhibitory inputs and mimicked stimulation of competing mitral cells (MCs) with different odorants. We performed dual whole-cell patch recording of evoked excitatory postsynaptic responses (EPSPs) and inhibitory postsynaptic responses (IPSPs) in current-clamp mode from two competitive MCs that are connected to the two stimulated glomeruli in slices of the main olfactory bulb in 2-3-week-old rats. We deliberately held the recorded cells at a relative hyperpolarized potential. This manipulation not only suppressed action potential generation but also excluded the possible contamination of inhibitory components in excitatory inputs. We found that in weakly activated MCs repetitive EPSP-IPSP interactions (5 Hz, 180 times) induced long-term potentiation (LTP) and long-term depression (LTD) in convergent excitatory and inhibitory inputs, respectively. Unexpectedly, these forms of plasticity depend on activity of somatic (mainly non-synaptic) NMDA receptors (NMDARs). In contrast, the same repetitive stimulation induced the LTP of excitatory inputs in strongly activated MCs (MC2) that require activity of synaptic NMDARs. These distinct forms of plasticity in the developing olfactory circuit may represent a novel rule of modification in convergent inputs that leads to decorrelation of inputs and facilitates odor discrimination. PMID:24704517

  11. RyR2 Modulates a Ca2+-Activated K+ Current in Mouse Cardiac Myocytes

    PubMed Central

    Mu, Yong-hui; Zhao, Wen-chao; Duan, Ping; Chen, Yun; Zhao, Wei-da; Wang, Qian; Tu, Hui-yin; Zhang, Qian

    2014-01-01

    In cardiomyocytes, Ca2+ entry through voltage-dependent Ca2+ channels (VDCCs) binds to and activates RyR2 channels, resulting in subsequent Ca2+ release from the sarcoplasmic reticulum (SR) and cardiac contraction. Previous research has documented the molecular coupling of small-conductance Ca2+-activated K+ channels (SK channels) to VDCCs in mouse cardiac muscle. Little is known regarding the role of RyRs-sensitive Ca2+ release in the SK channels in cardiac muscle. In this study, using whole-cell patch clamp techniques, we observed that a Ca2+-activated K+ current (IK,Ca) recorded from isolated adult C57B/L mouse atrial myocytes was significantly decreased by ryanodine, an inhibitor of ryanodine receptor type 2 (RyR2), or by the co-application of ryanodine and thapsigargin, an inhibitor of the sarcoplasmic reticulum calcium ATPase (SERCA) (p<0.05, p<0.01, respectively). The activation of RyR2 by caffeine increased the IK,Ca in the cardiac cells (p<0.05, p<0.01, respectively). We further analyzed the effect of RyR2 knockdown on IK,Ca and Ca2+ in isolated adult mouse cardiomyocytes using a whole-cell patch clamp technique and confocal imaging. RyR2 knockdown in mouse atrial cells transduced with lentivirus-mediated small hairpin interference RNA (shRNA) exhibited a significant decrease in IK,Ca (p<0.05) and [Ca2+]i fluorescence intensity (p<0.01). An immunoprecipitated complex of SK2 and RyR2 was identified in native cardiac tissue by co-immunoprecipitation assays. Our findings indicate that RyR2-mediated Ca2+ release is responsible for the activation and modulation of SK channels in cardiac myocytes. PMID:24747296

  12. Calcitonin gene-related peptide activated ATP-sensitive K+ currents in rabbit arterial smooth muscle via protein kinase A.

    PubMed Central

    Quayle, J M; Bonev, A D; Brayden, J E; Nelson, M T

    1994-01-01

    1. Whole-cell K+ currents activated by calcitonin gene-related peptide (CGRP) in smooth muscle cells enzymatically isolated from rabbit mesenteric arteries were measured in the conventional and perforated configurations of the patch clamp technique. The signal transduction pathway from CGRP receptors to activation of potassium currents was investigated. 2. CGRP (10 nM) activated a whole-cell current that was blocked by glibenclamide (10 microM), an inhibitor of ATP-sensitive K+ channels. Elevating intracellular ATP reduced glibenclamide-sensitive currents. CGRP increased the glibenclamide-sensitive currents by 3- to 6-fold in cells dialysed with 0.1 mM ATP, 3.0 mM ATP or in intact cells. The reversal potential of the glibenclamide-sensitive current in the presence of CGRP shifted with the potassium equilibrium potential, while its current-voltage relationship exhibited little voltage dependence. 3. Forskolin (10 microM), an adenylyl cyclase activator, Sp-cAMPS (500 microM) and the catalytic subunit of protein kinase A increased glibenclamide-sensitive K+ currents 2.1-, 3.3- and 8.2-fold, respectively. 4. Nitric oxide and nitroprusside did not activate glibenclamide-sensitive K+ currents. 5. Dialysis of the cell's interior with inhibitors of protein kinase A (synthetic peptide inhibitor, 4.6 microM or H-8, 100 microM) completely blocked activation of K+ currents by CGRP. 6. Our results suggest the following signal transduction scheme for activation of K+ currents by CGRP in arterial smooth muscle: (1) CGRP stimulates adenylyl cyclase, which leads to an elevation of cAMP; (2) cAMP activates protein kinase A, which opens ATP-sensitive K+ channels. PMID:8189394

  13. Effect of Monophasic Pulsed Current on Heel Pain and Functional Activities caused by Plantar Fasciitis

    PubMed Central

    Alotaibi, Abdullah K.; Petrofsky, Jerrold S.; Daher, Noha S.; Lohman, Everett; Laymon, Michael; Syed, Hasan M.

    2015-01-01

    Background Plantar fasciitis (PF) is a soft tissue disorder considered to be one of the most common causes of inferior heel pain. The aim of this study was to investigate the effect of monophasic pulsed current (MPC) and MPC coupled with plantar fascia-specific stretching exercises (SE) on the treatment of PF. Material/Methods Forty-four participants (22 women and 22 men, with a mean age of 49 years) diagnosed with PF were randomly assigned to receive MPC (n=22) or MPC coupled with plantar fascia-specific SE (n=22). Prior to and after 4 weeks of treatment, participants underwent baseline evaluation; heel pain was evaluated using a visual analogue scale (VAS), heel tenderness threshold was quantified using a handheld pressure algometer (PA), and functional activities level was assessed using the Activities of Daily Living subscale of the Foot and Ankle Ability Measure (ADL/FAAM). Results Heel pain scores showed a significant reduction in both groups compared to baseline VAS scores (P<0.001). Heel tenderness improved significantly in both groups compared with baseline PA scores (P<0.001). Functional activity level improved significantly in both groups compared with baseline (ADL/FAAM) scores (P<0.001). However, no significant differences existed between the 2 treatment groups in all post-intervention outcome measures. Conclusions This trial showed that MPC is useful in treating inferior heel symptoms caused by PF. PMID:25791231

  14. Transcranial Direct Current Stimulation Modulates Neurogenesis and Microglia Activation in the Mouse Brain

    PubMed Central

    Pikhovych, Anton; Stolberg, Nina Paloma; Jessica Flitsch, Lea; Walter, Helene Luise; Graf, Rudolf; Fink, Gereon Rudolf; Schroeter, Michael

    2016-01-01

    Transcranial direct current stimulation (tDCS) has been suggested as an adjuvant tool to promote recovery of function after stroke, but the mechanisms of its action to date remain poorly understood. Moreover, studies aimed at unraveling those mechanisms have essentially been limited to the rat, where tDCS activates resident microglia as well as endogenous neural stem cells. Here we studied the effects of tDCS on microglia activation and neurogenesis in the mouse brain. Male wild-type mice were subjected to multisession tDCS of either anodal or cathodal polarity; sham-stimulated mice served as control. Activated microglia in the cerebral cortex and neuroblasts generated in the subventricular zone as the major neural stem cell niche were assessed immunohistochemically. Multisession tDCS at a sublesional charge density led to a polarity-dependent downregulation of the constitutive expression of Iba1 by microglia in the mouse cortex. In contrast, both anodal and, to an even greater extent, cathodal tDCS induced neurogenesis from the subventricular zone. Data suggest that tDCS elicits its action through multifacetted mechanisms, including immunomodulation and neurogenesis, and thus support the idea of using tDCS to induce regeneration and to promote recovery of function. Furthermore, data suggest that the effects of tDCS may be animal- and polarity-specific. PMID:27403166

  15. ASYMMETRIC SUNSPOT ACTIVITY AND THE SOUTHWARD DISPLACEMENT OF THE HELIOSPHERIC CURRENT SHEET

    SciTech Connect

    Wang, Y.-M.; Robbrecht, E. E-mail: eva.robbrecht@oma.be

    2011-08-01

    Observations of the interplanetary magnetic field (IMF) have suggested a statistical tendency for the heliospheric current sheet (HCS) to be shifted a few degrees southward of the heliographic equator during the period 1965-2010, particularly in the years near sunspot minimum. Using potential-field source-surface extrapolations and photospheric flux-transport simulations, we demonstrate that this southward displacement follows from Joy's law and the observed hemispheric asymmetry in the sunspot numbers, with activity being stronger in the southern (northern) hemisphere during the declining (rising) phase of cycles 20-23. The hemispheric asymmetry gives rise to an axisymmetric quadrupole field, whose equatorial zone has the sign of the leading-polarity flux in the dominant hemisphere; during the last four cycles, the polarity of the IMF around the equator thus tended to match that of the north polar field both before and after polar field reversal. However, large fluctuations are introduced by the nonaxisymmetric field components, which depend on the longitudinal distribution of sunspot activity in either hemisphere. Consistent with this model, the HCS showed an average northward displacement during cycle 19, when the 'usual' alternation was reversed and the northern hemisphere became far more active than the southern hemisphere during the declining phase of the cycle. We propose a new method for determining the north-south displacement of the HCS from coronal streamer observations.

  16. Input Multiplicities in Process Control.

    ERIC Educational Resources Information Center

    Koppel, Lowell B.

    1983-01-01

    Describes research investigating potential effect of input multiplicity on multivariable chemical process control systems. Several simple processes are shown to exhibit the possibility of theoretical developments on input multiplicity and closely related phenomena are discussed. (JN)

  17. Modeling and generating input processes

    SciTech Connect

    Johnson, M.E.

    1987-01-01

    This tutorial paper provides information relevant to the selection and generation of stochastic inputs to simulation studies. The primary area considered is multivariate but much of the philosophy at least is relevant to univariate inputs as well. 14 refs.

  18. On the Modeling of Electrical Effects Experienced by Space Explorers During Extra Vehicular Activities: Intracorporal Currents, Resistances, and Electric Fields

    NASA Technical Reports Server (NTRS)

    Cela, Carlos J.; Loizos, Kyle; Lazzi, Gianluca; Hamilton, Douglas; Lee, Raphael C.

    2011-01-01

    Recent research has shown that space explorers engaged in Extra Vehicular Activities (EVAs) may be exposed, under certain conditions, to undesired electrical currents. This work focuses on determining whether these undesired induced electrical currents could be responsible for involuntary neuromuscular activity in the subjects, possibly caused by either large diameter peripheral nerve activation or reflex activity from cutaneous afferent stimulation. An efficient multiresolution variant of the admittance method along with a millimeter-resolution model of a male human body were used to calculate induced electric fields, resistance between contact electrodes used to simulate the potential exposure condition, and currents induced in the human body model. Results show that, under realistic exposure conditions using a 15V source, current density magnitudes and total current injected are well above previously reported startle reaction thresholds. This indicates that, under the considered conditions, the subjects could experience involuntary motor response.

  19. Changes in Habitual and Active Sagittal Posture in Children and Adolescents with and without Visual Input – Implications for Diagnostic Analysis of Posture

    PubMed Central

    Mazet, Carola; Mazet, Dirk; Hammes, Annette; Schmitt, Eduard

    2016-01-01

    Introduction Poor posture in children and adolescents has a prevalence of 22-65% and is suggested to be responsible for back pain. To assess posture, photometric imaging of sagittal posture is widely used, but usually only habitual posture positions (resting position with minimal muscle activity) are analysed. Aim The objective of this study was 1) to investigate possible changes in posture-describing parameters in the sagittal plane, when the subjects changed from a habitual passive posture to an actively corrected posture, and 2) to investigate the changes in posture parameters when an actively corrected posture was to be maintained with closed eyes. Materials and Methods In a group of 216 male children and adolescents (average 12.4 ± 2.5 years, range 7.0 – 17.6 years), six sagittal posture parameters (body tilt BT, trunk incline TI, posture index PI, horizontal distances between ear, shoulder and hip and the perpendicular to the ankle joint) were determined by means of photometric imaging in an habitual passive posture position, in an actively erect posture with eyes open, and in active stance with eyes closed. The change in these parameters during the transition between the posture positions was analysed statistically (dependent t-Test or Wilcoxon-Test) after Bonferroni correction (p<0.004). Results When moving from a habitual passive to an active posture BT, TI, PI, dEar, dShoulder, and dHip decreased significantly(p< 0.004). When the eyes were closed, only the perpendicular distances (dEar, dShoulder, and dHip) increased significantly. The parameters that describe the alignment of the trunk sections in relation to each other (BT, TI, PI), remained unchanged in both actively regulated posture positions. Conclusion Changes in sagittal posture parameters that occur when a habitual passive posture switches into an active posture or when an active posture is to be maintained while the eyes are closed can be used for diagnostic purposes regarding poor posture

  20. A biophysical model examining the role of low-voltage-activated potassium currents in shaping the responses of vestibular ganglion neurons.

    PubMed

    Hight, Ariel E; Kalluri, Radha

    2016-08-01

    The vestibular nerve is characterized by two broad groups of neurons that differ in the timing of their interspike intervals; some fire at highly regular intervals, whereas others fire at highly irregular intervals. Heterogeneity in ion channel properties has been proposed as shaping these firing patterns (Highstein SM, Politoff AL. Brain Res 150: 182-187, 1978; Smith CE, Goldberg JM. Biol Cybern 54: 41-51, 1986). Kalluri et al. (J Neurophysiol 104: 2034-2051, 2010) proposed that regularity is controlled by the density of low-voltage-activated potassium currents (IKL). To examine the impact of IKL on spike timing regularity, we implemented a single-compartment model with three conductances known to be present in the vestibular ganglion: transient sodium (gNa), low-voltage-activated potassium (gKL), and high-voltage-activated potassium (gKH). Consistent with in vitro observations, removing gKL depolarized resting potential, increased input resistance and membrane time constant, and converted current step-evoked firing patterns from transient (1 spike at current onset) to sustained (many spikes). Modeled neurons were driven with a time-varying synaptic conductance that captured the random arrival times and amplitudes of glutamate-driven synaptic events. In the presence of gKL, spiking occurred only in response to large events with fast onsets. Models without gKL exhibited greater integration by responding to the superposition of rapidly arriving events. Three synaptic conductance were modeled, each with different kinetics to represent a variety of different synaptic processes. In response to all three types of synaptic conductance, models containing gKL produced spike trains with irregular interspike intervals. Only models lacking gKL when driven by rapidly arriving small excitatory postsynaptic currents were capable of generating regular spiking. PMID:27121577

  1. Significance of Input Correlations in Striatal Function

    PubMed Central

    Yim, Man Yi; Aertsen, Ad; Kumar, Arvind

    2011-01-01

    The striatum is the main input station of the basal ganglia and is strongly associated with motor and cognitive functions. Anatomical evidence suggests that individual striatal neurons are unlikely to share their inputs from the cortex. Using a biologically realistic large-scale network model of striatum and cortico-striatal projections, we provide a functional interpretation of the special anatomical structure of these projections. Specifically, we show that weak pairwise correlation within the pool of inputs to individual striatal neurons enhances the saliency of signal representation in the striatum. By contrast, correlations among the input pools of different striatal neurons render the signal representation less distinct from background activity. We suggest that for the network architecture of the striatum, there is a preferred cortico-striatal input configuration for optimal signal representation. It is further enhanced by the low-rate asynchronous background activity in striatum, supported by the balance between feedforward and feedback inhibitions in the striatal network. Thus, an appropriate combination of rates and correlations in the striatal input sets the stage for action selection presumably implemented in the basal ganglia. PMID:22125480

  2. Transcranial Direct Current Stimulation Modulates Cortical Neuronal Activity in Alzheimer's Disease

    PubMed Central

    Marceglia, Sara; Mrakic-Sposta, Simona; Rosa, Manuela; Ferrucci, Roberta; Mameli, Francesca; Vergari, Maurizio; Arlotti, Mattia; Ruggiero, Fabiana; Scarpini, Elio; Galimberti, Daniela; Barbieri, Sergio; Priori, Alberto

    2016-01-01

    Quantitative electroencephalography (qEEG) showed that Alzheimer's disease (AD) is characterized by increased theta power, decreased alpha and beta power, and decreased coherence in the alpha and theta band in posterior regions. These abnormalities are thought to be associated with functional disconnections among cortical areas, death of cortical neurons, axonal pathology, and cholinergic deficits. Since transcranial Direct Current Stimulation (tDCS) over the temporo-parietal area is thought to have beneficial effects in patients with AD, in this study we aimed to investigate whether tDCS benefits are related to tDCS-induced changes in cortical activity, as represented by qEEG. A weak anodal current (1.5 mA, 15 min) was delivered bilaterally over the temporal-parietal lobe to seven subjects with probable AD (Mini-Mental State Examination, MMSE score >20). EEG (21 electrodes, 10–20 international system) was recorded for 5 min with eyes closed before (baseline, t0) and 30 min after anodal and cathodal tDCS ended (t1). At the same time points, patients performed a Word Recognition Task (WRT) to assess working memory functions. The spectral power and the inter- and intra-hemispheric EEG coherence in different frequency bands (e.g., low frequencies, including delta and theta; high frequencies, including alpha and beta) were calculated for each subject at t0 and t1. tDCS-induced changes in EEG neurophysiological markers were correlated with the performance of patients at the WRT. At baseline, qEEG features in AD patients confirmed that the decreased high frequency power was correlated with lower MMSE. After anodal tDCS, we observed an increase in the high-frequency power in the temporo-parietal area and an increase in the temporo-parieto-occipital coherence that correlated with the improvement at the WRT. In addition, cathodal tDCS produced a non-specific effect of decreased theta power all over the scalp that was not correlated with the clinical observation at the WRT

  3. Transcranial Direct Current Stimulation Modulates Cortical Neuronal Activity in Alzheimer's Disease.

    PubMed

    Marceglia, Sara; Mrakic-Sposta, Simona; Rosa, Manuela; Ferrucci, Roberta; Mameli, Francesca; Vergari, Maurizio; Arlotti, Mattia; Ruggiero, Fabiana; Scarpini, Elio; Galimberti, Daniela; Barbieri, Sergio; Priori, Alberto

    2016-01-01

    Quantitative electroencephalography (qEEG) showed that Alzheimer's disease (AD) is characterized by increased theta power, decreased alpha and beta power, and decreased coherence in the alpha and theta band in posterior regions. These abnormalities are thought to be associated with functional disconnections among cortical areas, death of cortical neurons, axonal pathology, and cholinergic deficits. Since transcranial Direct Current Stimulation (tDCS) over the temporo-parietal area is thought to have beneficial effects in patients with AD, in this study we aimed to investigate whether tDCS benefits are related to tDCS-induced changes in cortical activity, as represented by qEEG. A weak anodal current (1.5 mA, 15 min) was delivered bilaterally over the temporal-parietal lobe to seven subjects with probable AD (Mini-Mental State Examination, MMSE score >20). EEG (21 electrodes, 10-20 international system) was recorded for 5 min with eyes closed before (baseline, t0) and 30 min after anodal and cathodal tDCS ended (t1). At the same time points, patients performed a Word Recognition Task (WRT) to assess working memory functions. The spectral power and the inter- and intra-hemispheric EEG coherence in different frequency bands (e.g., low frequencies, including delta and theta; high frequencies, including alpha and beta) were calculated for each subject at t0 and t1. tDCS-induced changes in EEG neurophysiological markers were correlated with the performance of patients at the WRT. At baseline, qEEG features in AD patients confirmed that the decreased high frequency power was correlated with lower MMSE. After anodal tDCS, we observed an increase in the high-frequency power in the temporo-parietal area and an increase in the temporo-parieto-occipital coherence that correlated with the improvement at the WRT. In addition, cathodal tDCS produced a non-specific effect of decreased theta power all over the scalp that was not correlated with the clinical observation at the WRT

  4. Current environmental, health, safety, and socioeconomic research activities related to oil shale: draft

    SciTech Connect

    Not Available

    1980-09-01

    This document was prepared for DOE Resource Applications. It provides a compilation of information on current environmental, health, safety and socioeconomic research activities related to oil shale. The information is the most recent available through August 29, 1980. Included are the following: (1) project title; (2) adminstering agency; (3) contractor; (4) project status; (5) funding level; (6) project schedule; (7) deliverable; and (8) key personnel. The data contained in these reports can be used in environmental impact analyses relating oil shale to various incentives given in the Alternative Fuels Bill. The information provided was obtained from computer search printouts, review of respective agency documents and communication with agency personnel. A complete list of references is provided. The sponsoring organizations include the Department of Energy, the Environmental Protection Agency, the Department of Agriculture, and the Department of Interior.

  5. Vaccines, adjuvants and dendritic cell activatorsCurrent Status and Future Challenges

    PubMed Central

    Obeid, Joseph M.; Hu, Yinin; Slingluff, Craig L.

    2015-01-01

    Cancer vaccines offer a low-toxicity approach to induce anticancer immune responses. They have shown promise for clinical benefit with one cancer vaccine approved in the U.S. for advanced prostate cancer. As other immune therapies are now clearly effective for treatment of advanced cancers of many histologies, there is renewed enthusiasm for optimizing cancer vaccines for use to prevent recurrence in early stage cancers and/or to combine with other immune therapies for therapy of advanced cancers. Future advancements in vaccine therapy will involve the identification and selection of effective antigen formulations, optimization of adjuvants, dendritic cell activation, and combination therapies. In this summary we present the current practice, the broad collection of challenges, and the promising future directions of vaccine therapy for cancer. PMID:26320060

  6. Generation of cAMP-Activated Chloride Currents by Expression of CFTR

    NASA Astrophysics Data System (ADS)

    Anderson, Matthew P.; Rich, Devra P.; Gregory, Richard J.; Smith, Alan E.; Welsh, Michael J.

    1991-02-01

    Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) cause cystic fibrosis. In order to evaluate its function, CFTR was expressed in HeLa, Chinese hamster ovary (CHO), and NIH 3T3 fibroblast cells, and anion permeability was assessed with a fluorescence microscopic assay and the whole-cell patch-clamp technique. Adenosine 3',5'-monophosphate (cAMP) increased anion permeability and chloride currents in cells expressing CFTR, but not in cells expressing a mutant CFTR (ΔF508) or in nontransfected cells. The simplest interpretation of these observations is that CFTR is itself a cAMP-activated chloride channel. The alternative interpretation, that CFTR directly or indirectly regulates chloride channels, requires that these cells have endogenous cryptic, chloride channels that are stimulated by cAMP only in the presence of CFTR.

  7. Population diversity and function of hyperpolarization-activated current in olfactory bulb mitral cells

    PubMed Central

    Angelo, Kamilla; Margrie, Troy W.

    2011-01-01

    Although neurons are known to exhibit a broad array of intrinsic properties that impact critically on the computations they perform, very few studies have quantified such biophysical diversity and its functional consequences. Using in vivo and in vitro whole-cell recordings here we show that mitral cells are extremely heterogeneous in their expression of a rebound depolarization (sag) at hyperpolarized potentials that is mediated by a ZD7288-sensitive current with properties typical of hyperpolarization-activated cyclic nucleotide gated (HCN) channels. The variability in sag expression reflects a functionally diverse population of mitral cells. For example, those cells with large amplitude sag exhibit more membrane noise, a lower rheobase and fire action potentials more regularly than cells where sag is absent. Thus, cell-to-cell variability in sag potential amplitude reflects diversity in the integrative properties of mitral cells that ensures a broad dynamic range for odor representation across these principal neurons. PMID:22355569

  8. Input-Based Incremental Vocabulary Instruction

    ERIC Educational Resources Information Center

    Barcroft, Joe

    2012-01-01

    This fascinating presentation of current research undoes numerous myths about how we most effectively learn new words in a second language. In clear, reader-friendly text, the author details the successful approach of IBI vocabulary instruction, which emphasizes the presentation of target vocabulary as input early on and the incremental (gradual)…

  9. Evaluation of the pharmacological activity of the major mexiletine metabolites on skeletal muscle sodium currents

    PubMed Central

    De Bellis, M; De Luca, A; Rana, F; Cavalluzzi, M M; Catalano, A; Lentini, G; Franchini, C; Tortorella, V; Conte Camerino, D

    2006-01-01

    Background and purpose: Mexiletine (Mex), an orally effective antiarrhythmic agent used to treat ventricular arrhythmias, has also been found to be effective for myotonia and neuropathic pain. It is extensively metabolized in humans but little information exists about the pharmacodynamic properties of its metabolites. Experimental approach: To determine their contribution to the clinical activity of Mex, p-hydroxy-mexiletine (PHM), hydroxy-methyl-mexiletine (HMM), N-hydroxy-mexiletine (NHM) (phase I reaction products) and N-carbonyloxy β-D-glucuronide (NMG) (phase II reaction product) were tested on sodium currents (INa) of frog skeletal muscle fibres. Sodium currents were elicited with depolarizing pulses from different holding potentials (HP=−140, −100, −70 mV) and stimulation frequencies (0.25, 0.5, 1, 2, 5, 10 Hz) using the vaseline-gap voltage-clamp method. Key results: All the hydroxylated derivatives blocked the sodium channel in a voltage- and use-dependent manner. The PHM, HMM and NHM metabolites were up to 10-fold less effective than the parent compound. However, HMM showed a greater use-dependent behaviour (10 Hz), compared to Mex and the other metabolites. Similar to Mex, these products behaved as inactivating channel blockers. Conjugation with glucuronic acid (NMG) resulted in almost complete abolition of the pharmacological activity of the parent compound. Conclusions and Implications: Thus, although less potent, the phase I metabolites tested demonstrated similar pharmacological behaviour to Mex and might contribute to its clinical profile. PMID:16921388

  10. SAS2H input for computing core activities of 4.5, 5.0, and 5.5 weight % {sup 235}U fuel for Sequoyah Nuclear Plant

    SciTech Connect

    Hermann, O.W.

    1994-08-01

    Sequoyah Nuclear Plant core activities at initial fuel enrichments of 4.5, 5.0, and 5.5 wt% {sup 235}U, required in nuclear safety evaluations, were computed by the SAS2H analysis sequence and the ORIGEN-S code within the SCALE-4.2 code system.

  11. Synchronization among neuronal pools without common inputs: in vivo study.

    PubMed

    Brama, Haya; Guberman, Shoshana; Abeles, Moshe; Stern, Edward; Kanter, Ido

    2015-11-01

    Periodic synchronization of activity among neuronal pools has been related to substantial neural processes and information throughput in the neocortical network. However, the mechanisms of generating such periodic synchronization among distributed pools of neurons remain unclear. We hypothesize that to a large extent there is interplay between the topology of the neocortical networks and their reverberating modes of activity. The firing synchronization is governed by a nonlocal mechanism, the network delay loops, such that distant neuronal pools without common drives can be synchronized. This theoretical interplay between network topology and the synchronized mode is verified using an iterative procedure of a single intracellularly recorded neuron in vivo, imitating the dynamics of the entire network. The input is injected to the neuron via the recording electrode as current and computed from the filtered, evoked spikes of its pre-synaptic sources, previously emulated by the same neuron. In this manner we approximate subthreshold synaptic inputs from afferent neuronal pools to the neuron. Embedding the activity of these recurrent motifs in the intact brain allows us to measure the effects of connection probability, synaptic strength, and ongoing activity on the neuronal synchrony. Our in vivo experiments indicate that an initial stimulus given to a single pool is dynamically evolving into the formations of zero-lag and cluster synchronization. By applying results from theoretical models and in vitro experiments to in vivo activity in the intact brain, we support the notion that this mechanism may account for the binding activity across distributed brain areas. PMID:25230822

  12. 75 FR 73101 - Agency Information Collection Activities; Proposed Collection; Comment Request; Current Good...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-29

    ... Collection; Comment Request; Current Good Manufacturing Practice Regulations for Medicated Feeds AGENCY: Food... appropriate, and other forms of information technology. Current Good Manufacturing Practice Regulations for... current good manufacturing practice (cGMP) regulations for drugs, including medicated feeds....

  13. 78 FR 17215 - Agency Information Collection Activities: Proposed Collection; Comment Request; Current Good...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-20

    ... Collection; Comment Request; Current Good Manufacturing Practice for Positron Emission Tomography Drugs... regulations on current good manufacturing practice (CGMP) for positron emission tomography (PET) drugs. DATES... of information technology. Current Good Manufacturing Practice for Positron Emission Tomography...

  14. 76 FR 45262 - Agency Information Collection Activities; Proposed Collection; Comment Request; Current Good...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-28

    ... Collection; Comment Request; Current Good Manufacturing Practices and Related Regulations for Blood and Blood... current good manufacturing practice (CGMP) and related regulations for blood and blood components; and... of information technology. Current Good Manufacturing Practices and Related Regulations for Blood...

  15. High-frequency matrix converter with square wave input

    SciTech Connect

    Carr, Joseph Alexander; Balda, Juan Carlos

    2015-03-31

    A device for producing an alternating current output voltage from a high-frequency, square-wave input voltage comprising, high-frequency, square-wave input a matrix converter and a control system. The matrix converter comprises a plurality of electrical switches. The high-frequency input and the matrix converter are electrically connected to each other. The control system is connected to each switch of the matrix converter. The control system is electrically connected to the input of the matrix converter. The control system is configured to operate each electrical switch of the matrix converter converting a high-frequency, square-wave input voltage across the first input port of the matrix converter and the second input port of the matrix converter to an alternating current output voltage at the output of the matrix converter.

  16. Fe, O, and C Charge States Associated with Quiescent Versus Active Current Sheets in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Suess, S. T.; Ko, Y.-K.; vonSteiger, R.

    2008-01-01

    Ulysses MAG data were used to locate the heliospheric current sheet in data from 1991 through 2006. The purpose was to characterize typical charge states for Fe, O, and C in the vicinity of the current sheet and provide insight into the physical sources for these charge states in the corona. A study of He/H around the current sheets has led to a clear distinction between quiescent current sheets at times of low solar activity and active current sheets associated with magnetic clouds (and, presumably, ICMES). It has been shown that high ionization state Fe is produced in the corona in current sheets associated with CMEs through spectroscopic observations of the corona and through in situ detection at Ulysses. Here we show that the ionization state of Fe is typically only enhanced around active current sheets while the ionization states of O and C are commonly enhanced around both quiescent and active current sheets. This is consistent with UV coronal spectroscopy, which has shown that reconnection in current sheets behind CMEs leads to high temperatures not typically seen above quiet streamers.

  17. Current and future activities of the Observatoire de Haute Provence in Education and Public Outreach

    NASA Astrophysics Data System (ADS)

    Boër, M.; Ducerf, D.

    The Haute Provence Observatory OHP is an observation station located 100km North of Marseille France It performs both astronomical observations and routine atmospheric measurements in the NDSC Network for Data on Stratospheric Changes and several other geophysics national and international networks The site offers also a program directed to the general public the teachers the pupils and the students at all levels In the past two years we reinforced these activities following few guidelines enhance the scientific diffusion activities towards the general public by presenting an exhibition a stronger program for the teachers and the implementation of a project oriented program for the high school and university students We participate also to a curriculum for planetarium attendants We are currently defining the general long term plan for the observatory including a strong EPO program taking advantages of the site visitors facilities guesthouse research group EPO personnel This program will be oriented to the general space and planetary sciences and is prepared in cooperation with both the academic and regional authorities

  18. A current model of neural circuitry active in forming mental images

    PubMed Central

    Brodziak, Andrzej

    2013-01-01

    My aim here is to formulate a compact, intuitively understandable model of neural circuits active in imagination that would be consistent with the current state of knowledge, but that would be simple enough to be able to use for teaching. I argue that such a model should be based on the recent idea of “concept neurons” and circuits of 2 separate loops necessary for recalling mental images and consolidation of memory traces of long-term memory. This paper discusses the role of the hippocampus and temporal lobe, emphasizing the essential importance of recurrent pathways and oscillations occurring in the upper layers of hierarchical neural structures, as well as oscillations in thalamo-cortical loops. The elaborated model helps explain specific processes such as imagining future situations, novel objects, and anticipated action, as well as imagination concerning oneself, which is indispensable for the sense of identity and self-awareness. I attempt to present this compact, simple model of neural circuitry active in imagination by using some intuitive, demonstrative figures. PMID:24335907

  19. Logarithmic InGaAs detectors with global shutter and active dark current reduction

    NASA Astrophysics Data System (ADS)

    Ni, Yang; Arion, Bogdan; Bouvier, Christian; Noguier, Vincent

    2015-05-01

    In this paper, we present newly developed logarithmic InGaAs detectors with global shuttering and also an active dark current reduction technique to ensure ambient temperature operation without TEC for industrial applications. The newly released detectors come with both VGA (15um pitch) and QVGA (25um pitch) resolutions, giving the possibility to use lens less than 1-inch size. The logarithmic response is obtained by using solar-cell mode InGaAs photodiodes. The VGA and QVGA ROICs have 3 analog memories inside each pixel which permit, except the classic ITR, IWR and CDS modes, a new differential imaging mode which can be a useful feature in active imaging systems. The photodiode frontend circuit, in pure voltage mode, is made with non-inverting amplifier instead of CTIA. The reason of this choice is that the exposure time can be shortened without need of excessive power consumption as in CTIA front-end. We think that this arrangement associated with true CDS could match the noise performance of CTIA based one. VGA and QVGA ROICs have been designed and manufactured by using 0.18um 1P4M CMOS process. Both ROIC have been tested with success and match the design targets. The first batch of both detectors is under fabrication and will be presented during the conference.

  20. Disruption of vascular Ca2+-activated chloride currents lowers blood pressure

    PubMed Central

    Heinze, Christoph; Seniuk, Anika; Sokolov, Maxim V.; Huebner, Antje K.; Klementowicz, Agnieszka E.; Szijártó, István A.; Schleifenbaum, Johanna; Vitzthum, Helga; Gollasch, Maik; Ehmke, Heimo; Schroeder, Björn C.; Hübner, Christian A.

    2014-01-01

    High blood pressure is the leading risk factor for death worldwide. One of the hallmarks is a rise of peripheral vascular resistance, which largely depends on arteriole tone. Ca2+-activated chloride currents (CaCCs) in vascular smooth muscle cells (VSMCs) are candidates for increasing vascular contractility. We analyzed the vascular tree and identified substantial CaCCs in VSMCs of the aorta and carotid arteries. CaCCs were small or absent in VSMCs of medium-sized vessels such as mesenteric arteries and larger retinal arterioles. In small vessels of the retina, brain, and skeletal muscle, where contractile intermediate cells or pericytes gradually replace VSMCs, CaCCs were particularly large. Targeted disruption of the calcium-activated chloride channel TMEM16A, also known as ANO1, in VSMCs, intermediate cells, and pericytes eliminated CaCCs in all vessels studied. Mice lacking vascular TMEM16A had lower systemic blood pressure and a decreased hypertensive response following vasoconstrictor treatment. There was no difference in contractility of medium-sized mesenteric arteries; however, responsiveness of the aorta and small retinal arterioles to the vasoconstriction-inducing drug U46619 was reduced. TMEM16A also was required for peripheral blood vessel contractility, as the response to U46619 was attenuated in isolated perfused hind limbs from mutant mice. Out data suggest that TMEM16A plays a general role in arteriolar and capillary blood flow and is a promising target for the treatment of hypertension. PMID:24401273

  1. Purification of Active Myrosinase from Plants by Aqueous Two-Phase Counter-Current Chromatography

    PubMed Central

    Wade, Kristina L.; Ito, Yoichiro; Ramarathnam, Aarthi; Holtzclaw, W. David; Fahey, Jed W.

    2014-01-01

    Introduction Myrosinase (thioglucoside glucohydrolase; E.C. 3.2.1.147), is a plant enzyme of increasing interest and importance to the biomedical community. Myrosinase catalyses the formation of isothiocyanates such as sulforaphane (frombroccoli) and 4-(α-l-rhamnopyranosyloxy)benzyl isothiocyanate (from moringa), which are potent inducers of the cytoprotective phase-2 response in humans, by hydrolysis of their abundant glucosinolate (β-thioglucoside N-hydroxysulphate) precursors. Objective To develop an aqueous two-phase counter-current chromatography (CCC) system for the rapid, three-step purification of catalytically active myrosinase. Methods A high-concentration potassium phosphate and polyethylene glycol biphasic aqueous two-phase system (ATPS) is used with a newly developed CCC configuration that utilises spiral-wound, flat-twisted tubing (with an ovoid cross-section). Results Making the initial crude plant extract directly in the ATPS and injecting only the lower phase permitted highly selective partitioning of the myrosinase complex before a short chromatography on a spiral disk CCC. Optimum phase retention and separation of myrosinase from other plant proteins afforded a 60-fold purification. Conclusion Catalytically active myrosinase is purified from 3-day broccoli sprouts, 7-day daikon sprouts, mustard seeds and the leaves of field-grown moringa trees, in a CCC system that is predictably scalable. PMID:25130502

  2. Current status of information transfer activity on food irradiation and consumer attitudes in Japan

    NASA Astrophysics Data System (ADS)

    Furuta, Masakazu

    2004-09-01

    For the purpose of public education of radiation and radiation-related technology towards school kids and their parents through efficient information transfer, ''RADIATION FAIR—the relationship between daily life and radiation" has been successfully held at Kintetsu Department Store, one of the major departmental stores in downtown Osaka, the second largest city in Japan during summer vacation in every August for 19 years. Currently various irradiated products available in our daily life including irradiated potatoes and spices were displayed together with explanatory panels and attractions. The number of participants has increased every year and constantly exceeded 20,000 in recent years. This activity has become a good medium for the consumer to recognize the quality of the irradiated potatoes which has been distributed in the market since 1974, and irradiated spices, the next candidate for the clearance under examination by Japanese government. Taking advantage of this opportunity, we have demonstrated toward the participants that irradiation-decontaminated spices are superior to conventional heat-treated ones in aromatic quality as well as conducting survey of the visitor's feeling on radiation and irradiated foods. These activities would be potentially effective to facilitate public acceptance of irradiation decontamination of spices.

  3. Estrogenic activity measured in a sewage treatment works treating industrial inputs containing high concentrations of alkylphenolic compounds--a case study.

    PubMed

    Sheahan, David A; Brighty, Geoff C; Daniel, Mic; Kirby, Sonia J; Hurst, Mark R; Kennedy, Joe; Morris, Steven; Routledge, Edwin J; Sumpter, John P; Waldock, Michael J

    2002-03-01

    Chemical analyses were combined with a biological assay to investigate the main estrogenic chemicals as they passed through a sewage treatment works (STW) and entered a river. The STW studied was unusual in that it received wastewater from the textile trade. This wastewater was shown to contain high concentrations of alkylphenol polyethoxylates and their degradation products, such as nonylphenol. High-performance liquid chromatography fractionation, combined with biological assay, showed that the majority of the estrogenic activity was contributed by the alkylphenolic chemicals and the natural estrogens 17beta-estradiol and estrone. Despite removal of a high proportion of the alkylphenolic chemicals by the various treatment processes within the STW, concentrations in the final effluent were still high compared to most other STW effluents in the United Kingdom. The effluent was very estrogenic to caged fish, as was the river water 2 and 5 km downstream of the STW, even though less so. Using various approaches, attempts were made to determine which group of chemicals contributed most to the estrogenic activity of the effluent. The analysis suggested that, in this unusual situation, the alkylphenolic chemicals may contribute the majority of the estrogenic activity of the effluent. However, this conclusion was based on a number of uncertainties that are presently unresolved and hence can be considered only tentative. PMID:11878463

  4. Lithium ions in nanomolar concentration modulate glycine-activated chloride current in rat hippocampal neurons.

    PubMed

    Solntseva, E I; Bukanova, J V; Kondratenko, R V; Skrebitsky, V G

    2016-03-01

    Lithium salts are successfully used to treat bipolar disorder. At the same time, according to recent data lithium may be considered as a candidate medication for the treatment of neurodegenerative disorders. The mechanisms of therapeutic action of lithium have not been fully elucidated. In particular, in the literature there are no data on the effect of lithium on the glycine receptors. In the present study we investigated the effect of Li(+) on glycine-activated chloride current (IGly) in rat isolated pyramidal hippocampal neurons using patch-clamp technique. The effects of Li(+) were studied with two glycine concentrations: 100 μM (EC50) and 500 μM (nearly saturating). Li(+) was applied to the cell in two ways: first, by 600 ms co-application with glycine through micropipette (short application), and, second, by addition to an extracellular perfusate for 10 min (longer application). Li(+) was used in the range of concentrations of 1 nM-1 mM. Short application of Li(+) caused two effects: (1) an acceleration of desensitization (a decrease in the time of half-decay, or "τ") of IGly induced by both 100 μM and 500 μM glycine, and (2) a reduction of the peak amplitude of the IGly, induced by 100 μM, but not by 500 μM glycine. Both effects were not voltage-dependent. Dose-response curves for both effects were N-shaped with two maximums at 100 nM and 1 mM of Li(+) and a minimum at 1 μM of Li(+). This complex form of dose-response may indicate that the process activated by high concentrations of lithium inhibits the process that is sensitive to low concentrations of lithium. Longer application of Li(+)caused similar effects, but in this case 1 μM lithium was effective and the dose-effect curves were not N-shaped. The inhibitory effect of lithium ions on glycine-activated current suggests that lithium in low concentrations is able to modulate tonic inhibition in the hippocampus. This important property of lithium should be considered when using this drug as a

  5. Active Landslide Erosion of Mars' North Polar Cliffs: Current Rates, Causes, and Implications

    NASA Astrophysics Data System (ADS)

    Russell, P. S.; Byrne, S.; Pathare, A.

    2014-12-01

    While the North Polar Layered Deposits (NPLD) have long been considered Mars' best climate record, only recently have some of the processes governing the evolution of the NPLD to their current form been discovered and even directly observed. MOC revealed outcrops of an interbedded ice and dark-sand "basal unit" (BU) below steep NPLD scarps. Some bright markings on the BU were suggested to be talus deposits of mass-wasted NPLD ice, caused by undercutting via removal of easily erodible BU sand. In previous work with HiRISE images that confirmed the origin of these deposits, we: detailed their meter-scale morphology, constituent features, and variability; identified fractures of BU ice layers and NPLD scarps as additional mass-wasting facilitators; and, based on inter- and inter-annual monitoring, discovered that new deposits appear over time, thereby establishing mass wasting (of both BU and NPLD ice) as a currently active process. Here, we advance from qualitative descriptions of new, active processes to quantification of the rates at which they are occurring. From ~4 years of HiRISE observations, we cataloged the location, volume, source, and timing constraints of >160 landslide events along ~ 20 km of BU-NPLD scarp. Average rates are ~44 events/yr and ~2000 m3/yr, although 7 large events account for ~3/4 of the volume; this is a very geologically dynamic environment. BU events are more frequent and smaller than NPLD events, reflecting the relative thickness of ice source deposits but also perhaps differing proportions of two causal mechanisms: sand-removal undercutting and thermal-stress induced expansion, contraction, and fracturing. BU events prefer summer over spring; NPLD events strongly prefer fall-winter over spring-summer. We compare this observational data with 1) thermal stress models of the ice scarp to assess consistency in timing of activity, and 2) sublimation models of the ice scarp to assess the relative contributions to scarp retreat - our

  6. Input of UAV, DTM photo-interpretation and SAR interferometry on active tectonics applied on the Southern Coastal Range (SE Taiwan)

    NASA Astrophysics Data System (ADS)

    Deffontaines, Benoit; Chang, Kuo-Jen; Champenois, Johann; Magalhaes, Samuel; Serries, Gregory

    2016-04-01

    Taiwan is an excellent geomorphic laboratory where both extreme climatic events and high active tectonics compete. Moreover many Earth Sciences and Environmental data bases exist nowadays that help to better constrain both structural geology and active deformations. The latter unfortunately is still poorly known in the Cosatal Range of E.Taiwan in terms of geology due to access difficulties, high relief, paucity of roads, tropical vegetation and high climatic events (typhoons and heavy rainfall) and so on. Indirect methods such as photogrammetric survey using UAV's helps a lot to get high resolution topographic DEM and DTM, better than 10cm in planimetry, that helps a lot to get through careful photo-interpretation, a bird's eye view of the geology. Therefore we were able to much update the famous pre-existing geological maps (Wang and Chen, 1993). Moreover, by combining our high resolution topographic results with those of SAR interferometry (database of Champenois et al, EPSL, 2012), we were able to identify, characterise and quantify the differential active features toward the LOS of the Coastal Range (eastern Taiwan). In order to synthetise and to model the deformation of that famous place, we herein constructed more than 500 parallel projected profiles in order to locate, characterize and quantify the active tectonic features and compare them to the topography and the updated photo-interpreted geology (this work). We then were able to reconstruct the structural geometry of the Coastal Range and the Longitudinal Valley in SE Taiwan. Among our results, we reveal and prove : 1. the whole 2cm differential surrection of the Coastal Range ; 2. the differential displacement between both Central and Coastal Ranges ; 3. we explain the location of the Pinantashi river situated within the Lichi melange that correspond to the maximum surrection of the Coastal Range ; 4. we reveal the different units and their relative displacement within the Coastal Range itself ; 5. we

  7. 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.

    PubMed Central

    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 approximately ATP approximately ATP gamma S. The derivatives alpha,beta-methylene-ATP, beta,gamma-methylene-ATP and beta,gamma-imido-ATP up to 500 microM had no significant effects. 4. The rank order of efficacy of ATP analogues in activating a non-specific cationic current, IATP, was 2-methylthio-ATP > ATP >> ATP gamma S. The rank order of potency was 2-methylthio-ATP approximately ATP. The EC50 of ATP gamma S could not be determined owing to its very low efficacy. 5. The ATP analogues alpha,beta-methylene-ATP, beta,gamma-methylene-ATP and beta,gamma-imido-ATP at 500 microM did not activate IATP but acted as antagonists of activation of IATP by ATP. 6. The results suggest that the increase in ICa amplitude induced by external ATP is due to activation of P2Y-purinoceptors. 7. The mechanism of IATP activation remains to be determined before the receptor subtype involved can be deduced. PMID:7858894

  8. Serial Input Output

    SciTech Connect

    Waite, Anthony; /SLAC

    2011-09-07

    Serial Input/Output (SIO) is designed to be a long term storage format of a sophistication somewhere between simple ASCII files and the techniques provided by inter alia Objectivity and Root. The former tend to be low density, information lossy (floating point numbers lose precision) and inflexible. The latter require abstract descriptions of the data with all that that implies in terms of extra complexity. The basic building blocks of SIO are streams, records and blocks. Streams provide the connections between the program and files. The user can define an arbitrary list of streams as required. A given stream must be opened for either reading or writing. SIO does not support read/write streams. If a stream is closed during the execution of a program, it can be reopened in either read or write mode to the same or a different file. Records represent a coherent grouping of data. Records consist of a collection of blocks (see next paragraph). The user can define a variety of records (headers, events, error logs, etc.) and request that any of them be written to any stream. When SIO reads a file, it first decodes the record name and if that record has been defined and unpacking has been requested for it, SIO proceeds to unpack the blocks. Blocks are user provided objects which do the real work of reading/writing the data. The user is responsible for writing the code for these blocks and for identifying these blocks to SIO at run time. To write a collection of blocks, the user must first connect them to a record. The record can then be written to a stream as described above. Note that the same block can be connected to many different records. When SIO reads a record, it scans through the blocks written and calls the corresponding block object (if it has been defined) to decode it. Undefined blocks are skipped. Each of these categories (streams, records and blocks) have some characteristics in common. Every stream, record and block has a name with the condition that each

  9. SDR input power estimation algorithms

    NASA Astrophysics Data System (ADS)

    Briones, J. C.; Nappier, J. M.

    The General Dynamics (GD) S-Band software defined radio (SDR) in the Space Communications and Navigation (SCAN) Testbed on the International Space Station (ISS) provides experimenters an opportunity to develop and demonstrate experimental waveforms in space. The SDR has an analog and a digital automatic gain control (AGC) and the response of the AGCs to changes in SDR input power and temperature was characterized prior to the launch and installation of the SCAN Testbed on the ISS. The AGCs were used to estimate the SDR input power and SNR of the received signal and the characterization results showed a nonlinear response to SDR input power and temperature. In order to estimate the SDR input from the AGCs, three algorithms were developed and implemented on the ground software of the SCAN Testbed. The algorithms include a linear straight line estimator, which used the digital AGC and the temperature to estimate the SDR input power over a narrower section of the SDR input power range. There is a linear adaptive filter algorithm that uses both AGCs and the temperature to estimate the SDR input power over a wide input power range. Finally, an algorithm that uses neural networks was designed to estimate the input power over a wide range. This paper describes the algorithms in detail and their associated performance in estimating the SDR input power.

  10. SDR Input Power Estimation Algorithms

    NASA Technical Reports Server (NTRS)

    Nappier, Jennifer M.; Briones, Janette C.

    2013-01-01

    The General Dynamics (GD) S-Band software defined radio (SDR) in the Space Communications and Navigation (SCAN) Testbed on the International Space Station (ISS) provides experimenters an opportunity to develop and demonstrate experimental waveforms in space. The SDR has an analog and a digital automatic gain control (AGC) and the response of the AGCs to changes in SDR input power and temperature was characterized prior to the launch and installation of the SCAN Testbed on the ISS. The AGCs were used to estimate the SDR input power and SNR of the received signal and the characterization results showed a nonlinear response to SDR input power and temperature. In order to estimate the SDR input from the AGCs, three algorithms were developed and implemented on the ground software of the SCAN Testbed. The algorithms include a linear straight line estimator, which used the digital AGC and the temperature to estimate the SDR input power over a narrower section of the SDR input power range. There is a linear adaptive filter algorithm that uses both AGCs and the temperature to estimate the SDR input power over a wide input power range. Finally, an algorithm that uses neural networks was designed to estimate the input power over a wide range. This paper describes the algorithms in detail and their associated performance in estimating the SDR input power.

  11. Use of Yohkoh SXT in Measuring the Net Current and CME Productivity of Active Regions

    NASA Technical Reports Server (NTRS)

    Falconer, D. A.; Moore, R. L.; Gary, G. A.; Six, N. Frank (Technical Monitor)

    2001-01-01

    In our investigation of the correlation of global nonpotentiality of active regions to their CME productivity (Falconer, D.A. 2001, JGR, in press, and Falconer, Moore, & Gary, 2000, EOS 82, 20 S323), we use Yohkoh SXT images for two purposes. The first use is to help resolve the 180 degree ambiguity in the direction of the observed transverse magnetic field. Resolution of the 180 degree ambiguity is important, since the net current, one of our measures of global nonpotentiality, is derived from integrating the dot product of the transverse field around a contour (I(sub N)=(integral)BT(raised dot)dl). The ambiguity results from the observed transverse field being determined from the linear polarization, which gives the plane of the direction, but leaves a 180 degrees ambiguity. Automated methods to resolve the ambiguity ranging from the simple acute angle rule (Falconer, D.A. 2001) to the more sophisticated annealing method (Metcalf T.R. 1994). For many active regions, especially ones that are nearly potential these methods work well. But for very nonpotential active regions where the shear angle (the angle between the observed and potential transverse field) is near 90 degrees throughout large swaths along the main neutral line, both methods can resolve the ambiguity incorrectly for long segments of the neutral line. By determining from coronal images, such as those from Yohkoh/SXT, the sense of shear along the main neutral line in the active region, these cases can be identified and corrected by a modification of the acute angle rule described here. The second use of Yohkoh/SXT in this study is to check for the cusped coronal arcades of long-duration eruptive flares. This signature is an excellent proxy for CMEs, and was used by Canfield, Hudson, and McKenzie (1999 GRL V26, 6, 627-630). This work is funded by NSF through the Space Weather Program and by NASA through the Solar Physics Supporting Research and Technology Program.

  12. Eruptive history, current activity and risk estimation using geospatial information in the Colima volcano, Mexico

    NASA Astrophysics Data System (ADS)

    Suarez-Plascencia, C.; Camarena-Garcia, M.; Nunez-Cornu, F. J.; Flores-Peña, S.

    2013-12-01

    avocado orchards and fruits like blueberries, raspberries, and blackberries within the radius of 15 km from the crater. The population dynamics in the Colima volcano area had a population of 552,954 inhabitants in 2010, and a growth at an annual rate of 1.6 percent of the total population. 60 percent of the populations live in 105 towns with a population less than 250 inhabitants. Also, the region showed an increase in vulnerability for the development of economic activities, supported by the highway, railway, natural gas pipelines and electrical infrastructure that connect to the Port of Manzanillo to Guadalajara city. With the use of geospatial information quantify the vulnerability, together with the hazard maps and exposure, enabled us to build the following volcanic risk maps: a) Exclusion areas and moderate hazard for explosive events (ballistic) and pyroclastic flows, b) Hazard map of lahars and debris flow, and c) Hazard map of ash-fall. The geospatial database, a GIS mapping and current volcano monitoring, are the basis of the Operational Plan Colima Volcano. Civil Protection by the state of Jalisco and the updating of urban development plans of municipalities converge on the volcano. These instruments of land planning will help reduce volcanic risk in the region.

  13. Limitations of short range Mexican hat connection for driving target selection in a 2D neural field: activity suppression and deviation from input stimuli

    PubMed Central

    Mégardon, Geoffrey; Tandonnet, Christophe; Sumner, Petroc; Guillaume, Alain

    2015-01-01

    Dynamic Neural Field models (DNF) often use a kernel of connection with short range excitation and long range inhibition. This organization has been suggested as a model for brain structures or for artificial systems involved in winner-take-all processes such as saliency localization, perceptual decision or target/action selection. A good example of such a DNF is the superior colliculus (SC), a key structure for eye movements. Recent results suggest that the superficial layers of the SC (SCs) exhibit relatively short range inhibition with a longer time constant than excitation. The aim of the present study was to further examine the properties of a DNF with such an inhibition pattern in the context of target selection. First we tested the effects of stimulus size and shape on when and where self-maintained clusters of firing neurons appeared, using three variants of the model. In each model variant, small stimuli led to rapid formation of a spiking cluster, a range of medium sizes led to the suppression of any activity on the network and hence to no target selection, while larger sizes led to delayed selection of multiple loci. Second, we tested the model with two stimuli separated by a varying distance. Again single, none, or multiple spiking clusters could occur, depending on distance and relative stimulus strength. For short distances, activity attracted toward the strongest stimulus, reminiscent of well-known behavioral data for saccadic eye movements, while for larger distances repulsion away from the second stimulus occurred. All these properties predicted by the model suggest that the SCs, or any other neural structure thought to implement a short range MH, is an imperfect winner-take-all system. Although, those properties call for systematic testing, the discussion gathers neurophysiological and behavioral data suggesting that such properties are indeed present in target selection for saccadic eye movements. PMID:26539103

  14. Limitations of short range Mexican hat connection for driving target selection in a 2D neural field: activity suppression and deviation from input stimuli.

    PubMed

    Mégardon, Geoffrey; Tandonnet, Christophe; Sumner, Petroc; Guillaume, Alain

    2015-01-01

    Dynamic Neural Field models (DNF) often use a kernel of connection with short range excitation and long range inhibition. This organization has been suggested as a model for brain structures or for artificial systems involved in winner-take-all processes such as saliency localization, perceptual decision or target/action selection. A good example of such a DNF is the superior colliculus (SC), a key structure for eye movements. Recent results suggest that the superficial layers of the SC (SCs) exhibit relatively short range inhibition with a longer time constant than excitation. The aim of the present study was to further examine the properties of a DNF with such an inhibition pattern in the context of target selection. First we tested the effects of stimulus size and shape on when and where self-maintained clusters of firing neurons appeared, using three variants of the model. In each model variant, small stimuli led to rapid formation of a spiking cluster, a range of medium sizes led to the suppression of any activity on the network and hence to no target selection, while larger sizes led to delayed selection of multiple loci. Second, we tested the model with two stimuli separated by a varying distance. Again single, none, or multiple spiking clusters could occur, depending on distance and relative stimulus strength. For short distances, activity attracted toward the strongest stimulus, reminiscent of well-known behavioral data for saccadic eye movements, while for larger distances repulsion away from the second stimulus occurred. All these properties predicted by the model suggest that the SCs, or any other neural structure thought to implement a short range MH, is an imperfect winner-take-all system. Although, those properties call for systematic testing, the discussion gathers neurophysiological and behavioral data suggesting that such properties are indeed present in target selection for saccadic eye movements. PMID:26539103

  15. Properties of the hyperpolarizing-activated current (if) in cells isolated from the rabbit sino-atrial node.

    PubMed Central

    DiFrancesco, D; Ferroni, A; Mazzanti, M; Tromba, C

    1986-01-01

    Individual cells were isolated from the sino-atrial node area of the rabbit heart using an enzyme medium containing collagenase and elastase. After enzymatic treatment the cells were placed in normal Tyrode solution, where beating resumed in a fraction of them. Isolated cells were studied in the whole cell configuration. Action potentials as well as membrane currents under voltage-clamp conditions were similar to those in multicellular preparations. Pulses to voltages more negative than about -50 mV caused activation of the hyperpolarizing-activated current, if. Investigation of the properties of this current was carried out under conditions that limited the influence of other current systems during voltage clamp. The if current activation range usually extended approximately from -50 to -100 mV, but varied from cell to cell. In several cases, pulsing to the region of -40 mV elicited a sizeable if. Both current activation and deactivation during voltage steps had S-shaped time courses. A high variability was however observed in the sigmoidal behaviour of if kinetics. Plots of the fully-activated current-voltage (I-V) relation in different extracellular Na and K concentrations showed that both ions carry the current if. While changes in the external Na concentration caused the current I-V relation to undergo simple shifts along the voltage axis, changes in extracellular K concentration were also associated with changes in its slope. Again, a large variability was observed in the increase of I-V slope on raising the external K concentration. The current if was strongly depressed by Cs, and the block induced by 5 mM-Cs was markedly voltage dependent. Adrenaline (1-5 microM) and noradrenaline (1 microM) increased the current if around the half-activation voltage range and accelerated its activation at more negative voltages. Often, however, drug application failed to elicit any modification of if. Current run-down was observed in nearly all cells, although at a highly

  16. Stress-Activated Electric Currents in the Earth Crust: How they Can and Cannot Flow (Invited)

    NASA Astrophysics Data System (ADS)

    Freund, F. T.; Bleier, T. E.; Bortnik, J.; Dahlgren, R.

    2010-12-01

    Dormant electronic charge carriers exist in rocks. They “wake up” when stresses are applied: electrons e’ and positive holes, h., the latter being defect electrons in the oxygen anion sublattice of minerals [1, 2]. The h. can flow out of the stressed subvolume. They can spread into the unstressed surrounding, turning the rocks into p-type semiconductors. They travel fast and far using energy levels at the upper edge of the valence bands. Contrary to the h., the co-activated electrons e’ cannot flow out and propagate through unstressed rocks: they are stuck in the activation volume. The situation is akin to that in an electrochemical battery except that, in the “rock battery”, the positive charge carriers are not cations but positive holes h.. In the laboratory it is easy to close the battery circuit by offering the electrons a metal contact and connecting the stressed and unstressed rock with a metal wire. This is useful to demonstrate the functioning of the “rock battery”. In the field the h. outflow from a stressed rock volume is restricted as long as there is no return path. This is an important point when we try to understand why pre-earthquake EM emission is widely considered “unreliable” [3, 4]. However, there are at least three conditions, under which circuit closure can be achieved in the field under realistic pre-earthquake situations: (i) via n-type conducting rocks; (ii) via electrolytic conductivity of water; and (iii) via the air when the air above the epicentral region becomes highly ionized. We report on examples where these three conditions might have allowed large currents to flow and strong EM signals to be emitted. [1] Freund, F.T. et al.: Electric currents streaming out of stressed igneous rocks - A step towards understanding pre-earthquake low frequency EM emissions, Phys. Chem. Earth 31, 389-396 (2006). [2] Freund, F.T.: Charge generation and propagation in rocks, J. Geodyn. 33, 545-572 (2002). [3] Johnston, M.J.S. and

  17. Transcranial Direct Current Stimulation Modulates Neuronal Activity and Learning in Pilot Training

    PubMed Central

    Choe, Jaehoon; Coffman, Brian A.; Bergstedt, Dylan T.; Ziegler, Matthias D.; Phillips, Matthew E.

    2016-01-01

    Skill acquisition requires distributed learning both within (online) and across (offline) days to consolidate experiences into newly learned abilities. In particular, piloting an aircraft requires skills developed from extensive training and practice. Here, we tested the hypothesis that transcranial direct current stimulation (tDCS) can modulate neuronal function to improve skill learning and performance during flight simulator training of aircraft landing procedures. Thirty-two right-handed participants consented to participate in four consecutive daily sessions of flight simulation training and received sham or anodal high-definition-tDCS to the right dorsolateral prefrontal cortex (DLPFC) or left motor cortex (M1) in a randomized, double-blind experiment. Continuous electroencephalography (EEG) and functional near infrared spectroscopy (fNIRS) were collected during flight simulation, n-back working memory, and resting-state assessments. tDCS of the right DLPFC increased midline-frontal theta-band activity in flight and n-back working memory training, confirming tDCS-related modulation of brain processes involved in executive function. This modulation corresponded to a significantly different online and offline learning rates for working memory accuracy and decreased inter-subject behavioral variability in flight and n-back tasks in the DLPFC stimulation group. Additionally, tDCS of left M1 increased parietal alpha power during flight tasks and tDCS to the right DLPFC increased midline frontal theta-band power during n-back and flight tasks. These results demonstrate a modulation of group variance in skill acquisition through an increasing in learned skill consistency in cognitive and real-world tasks with tDCS. Further, tDCS performance improvements corresponded to changes in electrophysiological and blood-oxygenation activity of the DLPFC and motor cortices, providing a stronger link between modulated neuronal function and behavior. PMID:26903841

  18. Transcranial Direct Current Stimulation Modulates Neuronal Activity and Learning in Pilot Training.

    PubMed

    Choe, Jaehoon; Coffman, Brian A; Bergstedt, Dylan T; Ziegler, Matthias D; Phillips, Matthew E

    2016-01-01

    Skill acquisition requires distributed learning both within (online) and across (offline) days to consolidate experiences into newly learned abilities. In particular, piloting an aircraft requires skills developed from extensive training and practice. Here, we tested the hypothesis that transcranial direct current stimulation (tDCS) can modulate neuronal function to improve skill learning and performance during flight simulator training of aircraft landing procedures. Thirty-two right-handed participants consented to participate in four consecutive daily sessions of flight simulation training and received sham or anodal high-definition-tDCS to the right dorsolateral prefrontal cortex (DLPFC) or left motor cortex (M1) in a randomized, double-blind experiment. Continuous electroencephalography (EEG) and functional near infrared spectroscopy (fNIRS) were collected during flight simulation, n-back working memory, and resting-state assessments. tDCS of the right DLPFC increased midline-frontal theta-band activity in flight and n-back working memory training, confirming tDCS-related modulation of brain processes involved in executive function. This modulation corresponded to a significantly different online and offline learning rates for working memory accuracy and decreased inter-subject behavioral variability in flight and n-back tasks in the DLPFC stimulation group. Additionally, tDCS of left M1 increased parietal alpha power during flight tasks and tDCS to the right DLPFC increased midline frontal theta-band power during n-back and flight tasks. These results demonstrate a modulation of group variance in skill acquisition through an increasing in learned skill consistency in cognitive and real-world tasks with tDCS. Further, tDCS performance improvements corresponded to changes in electrophysiological and blood-oxygenation activity of the DLPFC and motor cortices, providing a stronger link between modulated neuronal function and behavior. PMID:26903841

  19. Normal and Mutant Rhodopsin Activation Measured with the Early Receptor Current in a Unicellular Expression System

    PubMed Central

    Shukla, Pragati; Sullivan, Jack M.

    1999-01-01

    The early receptor current (ERC) represents molecular charge movement during rhodopsin conformational dynamics. To determine whether this time-resolved assay can probe various aspects of structure–function relationships in rhodopsin, we first measured properties of expressed normal human rhodopsin with ERC recordings. These studies were conducted in single fused giant cells containing on the order of a picogram of regenerated pigment. The action spectrum of the ERC of normal human opsin regenerated with 11-cis-retinal was fit by the human rhodopsin absorbance spectrum. Successive flashes extinguished ERC signals consistent with bleaching of a rhodopsin photopigment with a normal range of photosensitivity. ERC signals followed the univariance principle since millisecond-order relaxation kinetics were independent of the wavelength of the flash stimulus. After signal extinction, dark adaptation without added 11-cis-retinal resulted in spontaneous pigment regeneration from an intracellular store of chromophore remaining from earlier loading. After the ERC was extinguished, 350-nm flashes overlapping metarhodopsin-II absorption promoted immediate recovery of ERC charge motions identified by subsequent 500-nm flashes. Small inverted R2 signals were seen in response to some 350-nm flashes. These results indicate that the ERC can be photoregenerated from the metarhodopsin-II state. Regeneration with 9-cis-retinal permits recording of ERC signals consistent with flash activation of isorhodopsin. We initiated structure–function studies by measuring ERC signals in cells expressing the D83N and E134Q mutant human rhodopsin pigments. D83N ERCs were simplified in comparison with normal rhodopsin, while E134Q ERCs had only the early phase of charge motion. This study demonstrates that properties of normal rhodopsin can be accurately measured with the ERC assay and that a structure–function investigation of rapid activation processes in analogue and mutant visual pigments is

  20. Stretch-activated single ion channel currents in tissue-cultured embryonic chick skeletal muscle.

    PubMed Central

    Guharay, F; Sachs, F

    1984-01-01

    The membrane of tissue-cultured chick pectoral muscle contains an ionic channel which is activated by membrane stretch. Nicotinic channels and Ca2+-activated K+ channels are not affected by stretch. In 150 mM-external K+ and 150 mM-internal Na+ the channel has a conductance of 70 pS, linear current-voltage relationship between -50 and -140 mV and a reversal potential of +30 mV. Kinetic analysis of single-channel records indicates that there are one open (O) and three closed (C) states. The data can be fitted by the reaction scheme: C1-C2-C3-O. Only the rate constant that governs the C1-C2 transition (k1,2) is stretch-sensitive. None of the rates are voltage-sensitive. The rate constant k1,2 varies with the square of the tension as k1, 2 = k0 X e alpha T2, where alpha is a constant describing the sensitivity to stretch and T is the tension. A typical value of alpha is 0.08 (dyn cm-1)-2. Following exposure to cytochalasin B the channel becomes more sensitive to stretch. The stretch-sensitivity constant, alpha, increases from 0.08 to 2.4 (dyn cm-1)-2. The probability of the channel being open is strongly dependent upon the extracellular K+ concentration. With a suction of 2 cmHg the probability increases from 0.004 in normal saline (5 mM-K+) to 0.26 in 150 mM-K+. The channel appears to gather force from a large area of membrane (greater than 3 X 10(5) A2), probably by a cytochalasin-resistant cytoskeletal network. PMID:6086918

  1. Enhanced Sensitivity to Rapid Input Fluctuations by Nonlinear Threshold Dynamics in Neocortical Pyramidal Neurons.

    PubMed

    Mensi, Skander; Hagens, Olivier; Gerstner, Wulfram; Pozzorini, Christian

    2016-02-01

    The way in which single neurons transform input into output spike trains has fundamental consequences for network coding. Theories and modeling studies based on standard Integrate-and-Fire models implicitly assume that, in response to increasingly strong inputs, neurons modify their coding strategy by progressively reducing their selective sensitivity to rapid input fluctuations. Combining mathematical modeling with in vitro experiments, we demonstrate that, in L5 pyramidal neurons, the firing threshold dynamics adaptively adjust the effective timescale of somatic integration in order to preserve sensitivity to rapid signals over a broad range of input statistics. For that, a new Generalized Integrate-and-Fire model featuring nonlinear firing threshold dynamics and conductance-based adaptation is introduced that outperforms state-of-the-art neuron models in predicting the spiking activity of neurons responding to a variety of in vivo-like fluctuating currents. Our model allows for efficient parameter extraction and can be analytically mapped to a Generalized Linear Model in which both the input filter--describing somatic integration--and the spike-history filter--accounting for spike-frequency adaptation--dynamically adapt to the input statistics, as experimentally observed. Overall, our results provide new insights on the computational role of different biophysical processes known to underlie adaptive coding in single neurons and support previous theoretical findings indicating that the nonlinear dynamics of the firing threshold due to Na+-channel inactivation regulate the sensitivity to rapid input fluctuations. PMID:26907675

  2. Enhanced Sensitivity to Rapid Input Fluctuations by Nonlinear Threshold Dynamics in Neocortical Pyramidal Neurons

    PubMed Central

    Mensi, Skander; Hagens, Olivier; Gerstner, Wulfram; Pozzorini, Christian

    2016-01-01

    The way in which single neurons transform input into output spike trains has fundamental consequences for network coding. Theories and modeling studies based on standard Integrate-and-Fire models implicitly assume that, in response to increasingly strong inputs, neurons modify their coding strategy by progressively reducing their selective sensitivity to rapid input fluctuations. Combining mathematical modeling with in vitro experiments, we demonstrate that, in L5 pyramidal neurons, the firing threshold dynamics adaptively adjust the effective timescale of somatic integration in order to preserve sensitivity to rapid signals over a broad range of input statistics. For that, a new Generalized Integrate-and-Fire model featuring nonlinear firing threshold dynamics and conductance-based adaptation is introduced that outperforms state-of-the-art neuron models in predicting the spiking activity of neurons responding to a variety of in vivo-like fluctuating currents. Our model allows for efficient parameter extraction and can be analytically mapped to a Generalized Linear Model in which both the input filter—describing somatic integration—and the spike-history filter—accounting for spike-frequency adaptation—dynamically adapt to the input statistics, as experimentally observed. Overall, our results provide new insights on the computational role of different biophysical processes known to underlie adaptive coding in single neurons and support previous theoretical findings indicating that the nonlinear dynamics of the firing threshold due to Na+-channel inactivation regulate the sensitivity to rapid input fluctuations. PMID:26907675

  3. Developmental change in calcium-activated chloride current during the differentiation of Xenopus spinal neurons in culture.

    PubMed

    Hussy, N

    1991-09-01

    The duration and ionic dependence of action potentials change during the differentiation of embryonic amphibian spinal neurons both in vivo and in culture. The development of sodium, calcium, and potassium currents has been characterized in these cells and the shortening of the action potential has been shown to depend to a great extent on developmental changes of potassium currents. Previous evidence suggests that a chloride current may also be present in these embryonic neurons. Chloride currents were investigated with intracellular current-clamp and single-electrode and whole-cell voltage-clamp techniques. Most neurons exhibited a calcium-activated chloride current (ICl(Ca] that contributed to the postdepolarization following the action potential recorded in the absence of sodium and potassium currents. This current appeared to decrease in density and its deactivation rate increased during the first day in culture. Its incidence also declined during this period. A much larger Ca(2+)-dependent Cl- current was also observed in a subset of neurons after 24 hr, but was absent at earlier stages of development. The results suggest the presence of two Cl- currents with different developmental fates. The early current probably contributes to the repolarization of long calcium-dependent action potentials at initial stages of neuronal development, when potassium currents are small, and may serve to reduce the extent of repetitive firing. PMID:1715301

  4. 76 FR 26338 - Agency Information Collection Activities; Renewal Without Change of a Current Collection; Comment...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-06

    ... Current Collection; Comment Request ACTION: Notice and request for comments. SUMMARY: In order to comply... for such foreign bank (31 CFR 1010.630(e)). Current Action: Renewal without change to the...

  5. Current Perspectives on Physical Activity and Exercise Recommendations for Children and Adolescents With Autism Spectrum Disorders

    PubMed Central

    Srinivasan, Sudha M.; Pescatello, Linda S.

    2014-01-01

    Recent evidence suggests that childhood obesity is increasing in children who are developing typically as well as in children with developmental disabilities such as autism spectrum disorders (ASDs). Impairments specific to autism as well as general environmental factors could lead to an imbalance between the intake and expenditure of energy, leading to obesity. In this article, we describe the mechanisms by which autism-specific impairments contribute to obesity. The evidence on exercise interventions to improve physical fitness, address obesity, and reduce autism-specific impairments in children and adolescents with ASDs is discussed. Limited evidence is currently available for exercise interventions in individuals with ASDs. Therefore, literature on other pediatric developmental disabilities and children who are developing typically was reviewed to provide recommendations for clinicians to assess physical activity levels, to promote physical fitness, and to reduce obesity in children and adolescents with ASDs. There is a clear need for further systematic research to develop sensitive assessment tools and holistic multisystem and multifactorial obesity interventions that accommodate the social communication, motor, and behavioral impairments of individuals with ASDs. PMID:24525861

  6. [Current situation and measures to promote anti-doping activities in Japan].

    PubMed

    Asakawa, Shin

    2011-01-01

    After the Ministry of Edcation, Culture, Sports, Science and Technology of Japan has ratified the UNESCO "International Convention Fight against Doping in Sport" in December 2006, the government increased its support to Anti-Doping activities. About 5 years ago, the total number of doping control samples a year in Japan was around 2000, and this number was not enough to demonstrate Japanese athletes' cleanness to the rest of the world. However, after the government's ratification of the UNESCO international convention, the government increased its support both financially and politically. By receiving the increased support from the government, testing number has increased and reached 5000 samples a year. 5 years ago, our target athletes range was only international level athletes who compete in the Olympics or international events. As we expanded our testing numbers, the target range of the athletes was also expanded and national level athletes also became our targets. As a result, athletes without having adequate knowledge about anti-doping regulations became our target. This situation caused inadvertent anti-doping rule violation cases. Most of those anti-doping rule violations were the result of taking over-the-counter medicines, etc. In order to cope with those inadvertent anti-doping rule violation problems, we, Japan Anti-Doping Agency launched "Sport Pharmacist Project" in cooperation with Japan Pharmaceutical Association. In this project, we provide anti-doping information/regulation to the pharmacists and make those pharmacists knowledgeable about the current anti-doping rules and regulations. PMID:22129872

  7. TOPICAL REVIEW: Electric current activated/assisted sintering (ECAS): a review of patents 1906-2008

    NASA Astrophysics Data System (ADS)

    Grasso, Salvatore; Sakka, Yoshio; Maizza, Giovanni

    2009-10-01

    The electric current activated/assisted sintering (ECAS) is an ever growing class of versatile techniques for sintering particulate materials. Despite the tremendous advances over the last two decades in ECASed materials and products there is a lack of comprehensive reviews on ECAS apparatuses and methods. This paper fills the gap by tracing the progress of ECAS technology from 1906 to 2008 and surveys 642 ECAS patents published over more than a century. It is found that the ECAS technology was pioneered by Bloxam (1906 GB Patent No. 9020) who developed the first resistive sintering apparatus. The patents were searched by keywords or by cross-links and were withdrawn from the Japanese Patent Office (342 patents), the United States Patent and Trademark Office (175 patents), the Chinese State Intellectual Property Office of P.R.C. (69 patents) and the World Intellectual Property Organization (12 patents). A subset of 119 (out of 642) ECAS patents on methods and apparatuses was selected and described in detail with respect to their fundamental concepts, physical principles and importance in either present ECAS apparatuses or future ECAS technologies for enhancing efficiency, reliability, repeatability, controllability and productivity. The paper is divided into two parts, the first deals with the basic concepts, features and definitions of basic ECAS and the second analyzes the auxiliary devices/peripherals. The basic ECAS is classified with reference to discharge time (fast and ultrafast ECAS). The fundamental principles and definitions of ECAS are outlined in accordance with the scientific and patent literature.

  8. Control of plasma properties in a short direct-current glow discharge with active boundaries

    NASA Astrophysics Data System (ADS)

    Adams, S. F.; Demidov, V. I.; Bogdanov, E. A.; Koepke, M. E.; Kudryavtsev, A. A.; Kurlyandskaya, I. P.

    2016-02-01

    To demonstrate controlling electron/metastable density ratio and electron temperature by applying negative voltages to the active (conducting) discharge wall in a low-pressure plasma with nonlocal electron energy distribution function, modeling has been performed in a short (lacking the positive-column region) direct-current glow discharge with a cold cathode. The applied negative voltage can modify the trapping of the low-energy part of the energetic electrons that are emitted from the cathode sheath and that arise from the atomic and molecular processes in the plasma within the device volume. These electrons are responsible for heating the slow, thermal electrons, while production of slow electrons (ions) and metastable atoms is mostly due to the energetic electrons with higher energies. Increasing electron temperature results in increasing decay rate of slow, thermal electrons (ions), while decay rate of metastable atoms and production rates of slow electrons (ions) and metastable atoms practically are unchanged. The result is in the variation of electron/metastable density ratio and electron temperature with the variation of the wall negative voltage.

  9. A role of stretch-activated potassium currents in the regulation of uterine smooth muscle contraction.

    PubMed

    Buxton, Iain L O; Heyman, Nathanael; Wu, Yi-ying; Barnett, Scott; Ulrich, Craig

    2011-06-01

    Rates of premature birth are alarming and threaten societies and healthcare systems worldwide. Premature labor results in premature birth in over 50% of cases. Preterm birth accounts for three-quarters of infant morbidity and mortality. Children that survive birth before 34 weeks gestation often face life-long disability. Current treatments for preterm labor are wanting. No treatment has been found to be generally effective and none are systematically evaluated beyond 48 h. New approaches to the treatment of preterm labor are desperately needed. Recent studies from our laboratory suggest that the uterine muscle is a unique compartment with regulation of uterine relaxation unlike that of other smooth muscles. Here we discuss recent evidence that the mechanically activated 2-pore potassium channel, TREK-1, may contribute to contraction-relaxation signaling in uterine smooth muscle and that TREK-1 gene variants associated with human labor and preterm labor may lead to a better understanding of preterm labor and its possible prevention. PMID:21642947

  10. Modulating activity in the orbitofrontal cortex changes trustees' cooperation: A transcranial direct current stimulation study.

    PubMed

    Wang, Guangrong; Li, Jianbiao; Yin, Xile; Li, Shuaiqi; Wei, Mengxing

    2016-04-15

    Trust is one of the most important factors in human society, as it pervades almost all domains of the society. The trusting behavior of trustors is dependent on the belief about the cooperative (reciprocal) level of trustees. Thence what are the motives underlying the cooperative behavior? An important explanation is that guilt aversion can motivate cooperative behavior. The right orbitofrontal cortex (OFC) is the guilt-specific region, while there is little understanding on the causal effect of this network. We explored the causal effect of the OFC on cooperative behavior using transcranial direct current stimulation (tDCS). Sixty participants played the trust game as trustees, and they received either anodal tDCS over the right OFC and simultaneously cathodal electrode over the right dorsolateral prefrontal cortex (DLPFC), or sham stimulation. Experimental results showed that participants as trustees transferred back more money in the tDCS treatment than sham stimulation. This suggests that the activity of the right OFC has causal effects on cooperative behavior. PMID:26808605

  11. Noninvasive reconstruction of cardiac electrical activity: update on current methods, applications and challenges.

    PubMed

    Cluitmans, M J M; Peeters, R L M; Westra, R L; Volders, P G A

    2015-06-01

    Electrical activity at the level of the heart muscle can be noninvasively reconstructed from body-surface electrocardiograms (ECGs) and patient-specific torso-heart geometry. This modality, coined electrocardiographic imaging, could fill the gap between the noninvasive (low-resolution) 12-lead ECG and invasive (high-resolution) electrophysiology studies. Much progress has been made to establish electrocardiographic imaging, and clinical studies appear with increasing frequency. However, many assumptions and model choices are involved in its execution, and only limited validation has been performed. In this article, we will discuss the technical details, clinical applications and current limitations of commonly used methods in electrocardiographic imaging. It is important for clinicians to realise the influence of certain assumptions and model choices for correct and careful interpretation of the results. This, in combination with more extensive validation, will allow for exploitation of the full potential of noninvasive electrocardiographic imaging as a powerful clinical tool to expedite diagnosis, guide therapy and improve risk stratification. PMID:25896779

  12. Cellular electrical micro-impedance parameter artifacts produced by passive and active current regulation.

    PubMed

    English, Anthony E; Squire, James C; Moy, Alan B

    2008-03-01

    This study analyzes the cellular microelectrode voltage measurement errors produced by active and passive current regulation, and the propagation of these errors into cellular barrier function parameter estimates. The propagation of random and systematic errors into these parameters is accounted for within a Riemannian manifold framework consistent with information geometry. As a result, the full non-linearity of the model parameter state dependence, the instrumental noise distribution, and the systematic errors associated with the voltage to impedance conversion, are accounted for. Specifically, cellular model parameters are treated as the coordinates of a model space manifold that inherits a Riemannian metric from the data space. The model space metric is defined in terms of the pull back of an instrumental noise-dependent Fisher information metric. Additional noise sources produced by the evaluation of the cell-covered electrode model that is a function of a naked electrode random variable are also included in the analysis. Based on a circular cellular micro-impedance model in widespread use, this study shows that cellular barrier function parameter estimates are highly model state dependent. Systematic errors produced by coaxial lead capacitances and circuit loading can also lead to significant and model state-dependent parameter errors and should, therefore, be either reduced or corrected for analytically. PMID:18202917

  13. The Effect of Input-Based Instruction Type on the Acquisition of Spanish Accusative Clitics

    ERIC Educational Resources Information Center

    White, Justin

    2015-01-01

    The purpose of this paper is to compare structured input (SI) with other input-based instructional treatments. The input-based instructional types include: input flood (IF), text enhancement (TE), SI activities, and focused input (FI; SI without implicit negative feedback). Participants included 145 adult learners enrolled in an intermediate…

  14. MAM-2201, a synthetic cannabinoid drug of abuse, suppresses the synaptic input to cerebellar Purkinje cells via activation of presynaptic CB1 receptors.

    PubMed

    Irie, Tomohiko; Kikura-Hanajiri, Ruri; Usami, Makoto; Uchiyama, Nahoko; Goda, Yukihiro; Sekino, Yuko

    2015-08-01

    Herbal products containing synthetic cannabinoids-initially sold as legal alternatives to marijuana-have become major drugs of abuse. Among the synthetic cannabinoids, [1-(5-fluoropentyl)-1H-indol-3-yl](4-methyl-1-naphthalenyl)-methanone (MAM-2201) has been recently detected in herbal products and has psychoactive and intoxicating effects in humans, suggesting that MAM-2201 alters brain function. Nevertheless, the pharmacological actions of MAM-2201 on cannabinoid receptor type 1 (CB1R) and neuronal functions have not been elucidated. We found that MAM-2201 acted as an agonist of human CB1Rs expressed in AtT-20 cells. In whole-cell patch-clamp recordings made from Purkinje cells (PCs) in slice preparations of the mouse cerebellum, we also found that MAM-2201 inhibited glutamate release at parallel fiber-PC synapses via activation of presynaptic CB1Rs. MAM-2201 inhibited neurotransmitter release with an inhibitory concentration 50% of 0.36 μM. MAM-2201 caused greater inhibition of neurotransmitter release than Δ(9)-tetrahydrocannabinol within the range of 0.1-30 μM and JWH-018, one of the most popular and potent synthetic cannabinoids detected in the herbal products, within the range of 0.03-3 μM. MAM-2201 caused a concentration-dependent suppression of GABA release onto PCs. Furthermore, MAM-2201 induced suppression of glutamate release at climbing fiber-PC synapses, leading to reduced dendritic Ca(2+) transients in PCs. These results suggest that MAM-2201 is likely to suppress neurotransmitter release at CB1R-expressing synapses in humans. The reduction of neurotransmitter release from CB1R-containing synapses could contribute to some of the symptoms of synthetic cannabinoid intoxication including impairments in cerebellum-dependent motor coordination and motor learning. PMID:25747605

  15. 75 FR 72827 - Agency Information Collection Activities; Proposed Collection; Comment Request; Current Good...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-26

    ... Collection; Comment Request; Current Good Manufacturing Practice Regulations for Type A Medicated Articles... appropriate, and other forms of information technology. Current Good Manufacturing Practice Regulations for... authority to issue current good manufacturing practice (cGMP) regulations for drugs, including type...

  16. A TTX-sensitive inward sodium current contributes to spontaneous activity in newborn rabbit sino-atrial node cells.

    PubMed Central

    Baruscotti, M; DiFrancesco, D; Robinson, R B

    1996-01-01

    1. Single cells were isolated from the sinus node region of rabbits (2 days old to adult) to study the age-dependent contribution of the sodium current (iNa) to pacemaker activity. 2. Experiments were conducted in 50 mM Na(+)-Ca(2+)-free solution. All newborn cells (2-19 days) exhibited a TTX-sensitive, Mn(2+)-insensitive fast inward Na+ current (peak current density 115.5 +/- 11.9 pA pF-1 at 0 mV). Fifty per cent of young cells (20-40 days) possessed the current, but only one in ten adult cells. Current density decreased with development independently of cell capacitance. 3. Newborn cells exhibited a noticeable window current. With development, the position of the activation curve was shifted in the positive direction, while the inactivation was unaltered, resulting in reduced overlap of the two curves and hence less window current. 4. In newborn cells, 3 microM TTX significantly reduced all measured parameters of spontaneous action potentials, slowing rate by 63%. In contrast, there was no significant effect of TTX on rate or most of the same parameters in adult cells. 5. These results indicate that cells of the sinus node region exhibit a substantial TTX-sensitive current at birth. With development, both the density and frequency of occurrence of this current within the sinus node decrease, as does its contribution to automaticity. PMID:8730579

  17. Tonic Nanomolar Dopamine Enables an Activity-Dependent Phase Recovery Mechanism That Persistently Alters the Maximal Conductance of the Hyperpolarization-Activated Current in a Rhythmically Active Neuron

    PubMed Central

    Rodgers, Edmund W.; Fu, Jing Jing; Krenz, Wulf-Dieter C.

    2011-01-01

    The phases at which network neurons fire in rhythmic motor outputs are critically important for the proper generation of motor behaviors. The pyloric network in the crustacean stomatogastric ganglion generates a rhythmic motor output wherein neuronal phase relationships are remarkably invariant across individuals and throughout lifetimes. The mechanisms for maintaining these robust phase relationships over the long-term are not well described. Here we show that tonic nanomolar dopamine (DA) acts at type 1 DA receptors (D1Rs) to enable an activity-dependent mechanism that can contribute to phase maintenance in the lateral pyloric (LP) neuron. The LP displays continuous rhythmic bursting. The activity-dependent mechanism was triggered by a prolonged decrease in LP burst duration, and it generated a persistent increase in the maximal conductance (Gmax) of the LP hyperpolarization-activated current (Ih), but only in the presence of steady-state DA. Interestingly, micromolar DA produces an LP phase advance accompanied by a decrease in LP burst duration that abolishes normal LP network function. During a 1 h application of micromolar DA, LP phase recovered over tens of minutes because, the activity-dependent mechanism enabled by steady-state DA was triggered by the micromolar DA-induced decrease in LP burst duration. Presumably, this mechanism restored normal LP network function. These data suggest steady-state DA may enable homeostatic mechanisms that maintain motor network output during protracted neuromodulation. This DA-enabled, activity-dependent mechanism to preserve phase may be broadly relevant, as diminished dopaminergic tone has recently been shown to reduce Ih in rhythmically active neurons in the mammalian brain. PMID:22072689

  18. Frontier Science in the Polar Regions: Current Activities of the Polar Research Board

    NASA Astrophysics Data System (ADS)

    Brown, L. M.

    2011-12-01

    The National Academies (the umbrella term for the National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council) is a private, nonprofit organization chartered by Congress in 1863. The Polar Research Board (PRB) is the focal point within the Academies for providing advice on issues related to the Arctic, Antarctic, and cold regions in general. Tasks within the PRB mission include: providing a forum for the polar science community to address research needs and policy issues; conducting studies and workshops on emerging scientific and policy issues in response to requests from federal agencies and others; providing program reviews, guidance, and assessments of priorities; and facilitating communication on polar issues among academia, industry, and government. The PRB also serves as the US National Committee to two international, nongovernmental polar science organizations: the Scientific Committee on Antarctic Research (SCAR) and the International Arctic Science Committee (IASC). The polar regions are experiencing rapid changes in environment and climate, and the PRB has a number of completed and ongoing studies that will enhance scientific understanding of these issues. This poster will illustrate current PRB activities as well as results from two recently released reports: Frontiers in Understanding Climate Change and Polar Ecosystems and Future Science Opportunities in Antarctica and the Southern Ocean. In the former, a set of frontier research questions are developed to help scientists understand the impacts of climate change on polar ecosystems. The report builds on existing knowledge of climate change impacts and highlights the next big topics to be addressed in the coming decades. In addition, a number of methods and technologies are identified that will be useful to advance future research in polar ecosystem science. In the latter, changes to important science conducted on Antarctica and the surrounding

  19. Modeling of Novel Diagnostic Strategies for Active Tuberculosis – A Systematic Review: Current Practices and Recommendations

    PubMed Central

    Zwerling, Alice; White, Richard G.; Vassall, Anna; Cohen, Ted; Dowdy, David W.; Houben, Rein M. G. J.

    2014-01-01

    Introduction The field of diagnostics for active tuberculosis (TB) is rapidly developing. TB diagnostic modeling can help to inform policy makers and support complicated decisions on diagnostic strategy, with important budgetary implications. Demand for TB diagnostic modeling is likely to increase, and an evaluation of current practice is important. We aimed to systematically review all studies employing mathematical modeling to evaluate cost-effectiveness or epidemiological impact of novel diagnostic strategies for active TB. Methods Pubmed, personal libraries and reference lists were searched to identify eligible papers. We extracted data on a wide variety of model structure, parameter choices, sensitivity analyses and study conclusions, which were discussed during a meeting of content experts. Results & Discussion From 5619 records a total of 36 papers were included in the analysis. Sixteen papers included population impact/transmission modeling, 5 were health systems models, and 24 included estimates of cost-effectiveness. Transmission and health systems models included specific structure to explore the importance of the diagnostic pathway (n = 4), key determinants of diagnostic delay (n = 5), operational context (n = 5), and the pre-diagnostic infectious period (n = 1). The majority of models implemented sensitivity analysis, although only 18 studies described multi-way sensitivity analysis of more than 2 parameters simultaneously. Among the models used to make cost-effectiveness estimates, most frequent diagnostic assays studied included Xpert MTB/RIF (n = 7), and alternative nucleic acid amplification tests (NAATs) (n = 4). Most (n = 16) of the cost-effectiveness models compared new assays to an existing baseline and generated an incremental cost-effectiveness ratio (ICER). Conclusion Although models have addressed a small number of important issues, many decisions regarding implementation of TB diagnostics are being made without

  20. Current activities of Cardiovascular Rehabilitation in the ambulatory setting of the Lombardy Region.

    PubMed

    Ambrosetti, Marco; Pedretti, Roberto F E; Facchini, Mario; Malfatto, Gabriella; Riccobono, Salvatore Pio; Febo, Oreste; Diaco, Tommaso

    2016-01-01

    In the present work, the current activities of Cardiovascular Rehabilitation and Prevention (CRP) in the ambulatory setting of the Lombardy Region (Italy) are described. Based on the 2012 Legislation, ambulatory CRP is delivered by means of three programme categories (MAC 6, 7, and 8) with different degrees of intensity. The patient evaluation of global cardiovascular/clinical risk, comorbidity, and disability is the cornerstone for MAC prescription. Following the organization of MAC activities, a survey on 327 patients was carried out by the regional network of the Italian Society of Cardiovascular Rehabilitation (GICR-IACPR). Globally, acute coronary syndromes (with or without coronary revascularization) constituted the main access group to CRP. More than 60% of patients displayed a condition of high risk, comorbidity, and disability. The outcome of ambulatory CRP by means of MAC 6 and 7 was satisfactory, while in the 'less intensive' MAC 8 patients with complete drug up-titration and achievement of secondary prevention targets were no more than 70%. RiassuntoLa Cardiologia Riabilitativa e Preventiva (CRP) storicamente riconosce nei percorsi ambulatoriali un importante setting per l'erogazione dell'intervento. In Regione Lombardia negli ultimi anni le attività di CRP sono state oggetto di una profonda riorganizzazione, con il contributo di esperti GICR-IACPR attivi presso lo specifico tavolo tecnico attivato presso la Direzione Generale Sanità. Dal 2012 sono attive le Macroattività Ambulatoriali Complesse e ad alta integrazione di risorse (MAC), che riguardano anche la sfera della CRP. Le MAC si sono poste come integrazione e alternativa al percorso degenziale e sono state classificate in tre livelli a complessità decrescente (MAC 6, MAC 7 e MAC 8 nel nuovo nomenclatore delle attività ambulatoriali). Il network GICR-IACPR ha quindi successivamente condotto una survey su 327 pazienti in tre Centri di CRP, di cui vengono esposti i risultati. Complessivamente

  1. REL - English Bulk Data Input.

    ERIC Educational Resources Information Center

    Bigelow, Richard Henry

    A bulk data input processor which is available for the Rapidly Extensible Language (REL) English versions is described. In REL English versions, statements that declare names of data items and their interrelationships normally are lines from a terminal or cards in a batch input stream. These statements provide a convenient means of declaring some…

  2. Current mHealth Technologies for Physical Activity Assessment and Promotion

    PubMed Central

    O’Reilly, Gillian A.; Spruijt-Metz, Donna

    2014-01-01

    Context Novel mobile assessment and intervention capabilities are changing the face of physical activity (PA) research. A comprehensive systematic review of how mobile technology has been used for measuring PA and promoting PA behavior change is needed. Evidence acquisition Article collection was conducted using six databases from February to June 2012 with search terms related to mobile technology and PA. Articles that described the use of mobile technologies for PA assessment, sedentary behavior assessment, and/or interventions for PA behavior change were included. Articles were screened for inclusion and study information was extracted. Evidence synthesis Analyses were conducted from June to September 2012. Mobile phone–based journals and questionnaires, short message service (SMS) prompts, and on-body PA sensing systems were the mobile technologies most utilized. Results indicate that mobile journals and questionnaires are effective PA self-report measurement tools. Intervention studies that reported successful promotion of PA behavior change employed SMS communication, mobile journaling, or both SMS and mobile journaling. Conclusions mHealth technologies are increasingly being employed to assess and intervene on PA in clinical, epidemiologic, and intervention research. The wide variations in technologies used and outcomes measured limit comparability across studies, and hamper identification of the most promising technologies. Further, the pace of technologic advancement currently outstrips that of scientific inquiry. New adaptive, sequential research designs that take advantage of ongoing technology development are needed. At the same time, scientific norms must shift to accept “smart,” adaptive, iterative, evidence-based assessment and intervention technologies that will, by nature, improve during implementation. PMID:24050427

  3. High temperature current mirror amplifier

    DOEpatents

    Patterson, III, Raymond B.

    1984-05-22

    A high temperature current mirror amplifier having biasing means in the transdiode connection of the input transistor for producing a voltage to maintain the base-collector junction reversed-biased and a current means for maintaining a current through the biasing means at high temperatures so that the base-collector junction of the input transistor remained reversed-biased. For accuracy, a second current mirror is provided with a biasing means and current means on the input leg.

  4. Computer Generated Inputs for NMIS Processor Verification

    SciTech Connect

    J. A. Mullens; J. E. Breeding; J. A. McEvers; R. W. Wysor; L. G. Chiang; J. R. Lenarduzzi; J. T. Mihalczo; J. K. Mattingly

    2001-06-29

    Proper operation of the Nuclear Identification Materials System (NMIS) processor can be verified using computer-generated inputs [BIST (Built-In-Self-Test)] at the digital inputs. Preselected sequences of input pulses to all channels with known correlation functions are compared to the output of the processor. These types of verifications have been utilized in NMIS type correlation processors at the Oak Ridge National Laboratory since 1984. The use of this test confirmed a malfunction in a NMIS processor at the All-Russian Scientific Research Institute of Experimental Physics (VNIIEF) in 1998. The NMIS processor boards were returned to the U.S. for repair and subsequently used in NMIS passive and active measurements with Pu at VNIIEF in 1999.

  5. Multivariate autoregressive models with exogenous inputs for intracerebral responses to direct electrical stimulation of the human brain

    PubMed Central

    Chang, Jui-Yang; Pigorini, Andrea; Massimini, Marcello; Tononi, Giulio; Nobili, Lino; Van Veen, Barry D.

    2012-01-01

    A multivariate autoregressive (MVAR) model with exogenous inputs (MVARX) is developed for describing the cortical interactions excited by direct electrical current stimulation of the cortex. Current stimulation is challenging to model because it excites neurons in multiple locations both near and distant to the stimulation site. The approach presented here models these effects using an exogenous input that is passed through a bank of filters, one for each channel. The filtered input and a random input excite a MVAR system describing the interactions between cortical activity at the recording sites. The exogenous input filter coefficients, the autoregressive coefficients, and random input characteristics are estimated from the measured activity due to current stimulation. The effectiveness of the approach is demonstrated using intracranial recordings from three surgical epilepsy patients. We evaluate models for wakefulness and NREM sleep in these patients with two stimulation levels in one patient and two stimulation sites in another resulting in a total of 10 datasets. Excellent agreement between measured and model-predicted evoked responses is obtained across all datasets. Furthermore, one-step prediction is used to show that the model also describes dynamics in pre-stimulus and evoked recordings. We also compare integrated information—a measure of intracortical communication thought to reflect the capacity for consciousness—associated with the network model in wakefulness and sleep. As predicted, higher information integration is found in wakefulness than in sleep for all five cases. PMID:23226122

  6. Multiphase soft switched DC/DC converter and active control technique for fuel cell ripple current elimination

    DOEpatents

    Lai, Jih-Sheng; Liu, Changrong; Ridenour, Amy

    2009-04-14

    DC/DC converter has a transformer having primary coils connected to an input side and secondary coils connected to an output side. Each primary coil connects a full-bridge circuit comprising two switches on two legs, the primary coil being connected between the switches on each leg, each full-bridge circuit being connected in parallel wherein each leg is disposed parallel to one another, and the secondary coils connected to a rectifying circuit. An outer loop control circuit that reduces ripple in a voltage reference has a first resistor connected in series with a second resistor connected in series with a first capacitor which are connected in parallel with a second capacitor. An inner loop control circuit that reduces ripple in a current reference has a third resistor connected in series with a fourth resistor connected in series with a third capacitor which are connected in parallel with a fourth capacitor.

  7. 78 FR 69134 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Current...

    Federal Register 2010, 2011, 2012, 2013, 2014

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    Federal Register 2010, 2011, 2012, 2013, 2014

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  12. Functional expression of the hyperpolarization-activated, non-selective cation current If in immortalized HL-1 cardiomyocytes

    PubMed Central

    Sartiani, Laura; Bochet, Pascal; Cerbai, Elisabetta; Mugelli, Alessandro; Fischmeister, Rodolphe

    2002-01-01

    HL-1 cells are adult mouse atrial myocytes induced to proliferate indefinitely by SV40 large T antigen. These cells beat spontaneously when confluent and express several adult cardiac cell markers including the outward delayed rectifier K+ channel. Here, we examined the presence of a hyperpolarization-activated If current in HL-1 cells using the whole-cell patch-clamp technique on isolated cells enzymatically dissociated from the culture at confluence. Cell membrane capacitance (Cm) ranged from 5 to 53 pF. If was detected in about 30 % of the cells and its occurrence was independent of the stage of the culture. If maximal slope conductance was 89.7 ± 0.4 pS pF−1 (n = 10). If current in HL-1 cells showed typical characteristics of native cardiac If current: activation threshold between −50 and −60 mV, half-maximal activation potential of −83.1 ± 0.7 mV (n = 50), reversal potential at −20.8 ± 1.5 mV (n = 10), time-dependent activation by hyperpolarization and blockade by 4 mm Cs+. In half of the cells tested, activation of adenylyl cyclase by the forskolin analogue L858051 (20 μm) induced both a ≈6 mV positive shift of the half-activation potential and a ≈37 % increase in the fully activated If current. RT-PCR analysis of the hyperpolarization-activated, cyclic nucleotide-gated channels (HCN) expressed in HL-1 cells demonstrated major contributions of HCN1 and HCN2 channel isoforms to If current. Cytosolic Ca2+ oscillations in spontaneously beating HL-1 cells were measured in Fluo-3 AM-loaded cells using a fast-scanning confocal microscope. The oscillation frequency ranged from 1.3 to 5 Hz and the spontaneous activity was stopped in the presence of 4 mm Cs+. Action potentials from HL-1 cells had a triangular shape, with an overshoot at +15 mV and a maximal diastolic potential of −69 mV, i.e. more negative than the threshold potential for If activation. In conclusion, HL-1 cells display a hyperpolarization-activated If current which might

  13. Functional expression of the hyperpolarization-activated, non-selective cation current I(f) in immortalized HL-1 cardiomyocytes.

    PubMed

    Sartiani, Laura; Bochet, Pascal; Cerbai, Elisabetta; Mugelli, Alessandro; Fischmeister, Rodolphe

    2002-11-15

    HL-1 cells are adult mouse atrial myocytes induced to proliferate indefinitely by SV40 large T antigen. These cells beat spontaneously when confluent and express several adult cardiac cell markers including the outward delayed rectifier K(+) channel. Here, we examined the presence of a hyperpolarization-activated I(f) current in HL-1 cells using the whole-cell patch-clamp technique on isolated cells enzymatically dissociated from the culture at confluence. Cell membrane capacitance (C(m)) ranged from 5 to 53 pF. I(f) was detected in about 30% of the cells and its occurrence was independent of the stage of the culture. I(f) maximal slope conductance was 89.7 +/- 0.4 pS pF(-1) (n = 10). I(f) current in HL-1 cells showed typical characteristics of native cardiac I(f) current: activation threshold between -50 and -60 mV, half-maximal activation potential of -83.1 +/- 0.7 mV (n = 50), reversal potential at -20.8 +/- 1.5 mV (n = 10), time-dependent activation by hyperpolarization and blockade by 4 mM Cs(+). In half of the cells tested, activation of adenylyl cyclase by the forskolin analogue L858051 (20 microM) induced both an approximately 6 mV positive shift of the half-activation potential and an approximately 37 % increase in the fully activated I(f) current. RT-PCR analysis of the hyperpolarization-activated, cyclic nucleotide-gated channels (HCN) expressed in HL-1 cells demonstrated major contributions of HCN1 and HCN2 channel isoforms to I(f) current. Cytosolic Ca(2+) oscillations in spontaneously beating HL-1 cells were measured in Fluo-3 AM-loaded cells using a fast-scanning confocal microscope. The oscillation frequency ranged from 1.3 to 5 Hz and the spontaneous activity was stopped in the presence of 4 mM Cs(+). Action potentials from HL-1 cells had a triangular shape, with an overshoot at +15 mV and a maximal diastolic potential of -69 mV, i.e. more negative than the threshold potential for I(f) activation. In conclusion, HL-1 cells display a

  14. The SEDIBUD (Sediment Budgets in Cold Environments) Programme: Current activities and future key tasks

    NASA Astrophysics Data System (ADS)

    Beylich, A. A.; Lamoureux, S. F.; Decaulne, A.

    2012-04-01

    Projected climate change in cold regions is expected to alter melt season duration and intensity, along with the number of extreme rainfall events, total annual precipitation and the balance between snowfall and rainfall. Similarly, changes to the thermal balance are expected to reduce the extent of permafrost and seasonal ground frost and increase active layer depths. These effects will undoubtedly change surface environments in cold regions and alter the fluxes of sediments, nutrients and solutes, but the absence of quantitative data and coordinated process monitoring and analysis to understand the sensitivity of the Earth surface environment is acute in cold climate environments. The International Association of Geomorphologists (I.A.G./A.I.G.)SEDIBUD (Sediment Budgets in Cold Environments) Programme was formed in 2005 to address this existing key knowledge gap. SEDIBUD currently has about 400 members worldwide and the Steering Committee of this international programme is composed of ten scientists from eight different countries: Achim A. Beylich (Chair) (Norway), Armelle Decaulne (Secretary) (France), John C. Dixon (USA), Scott F. Lamoureux (Vice-Chair) (Canada), John F. Orwin (Canada), Jan-Christoph Otto (Austria), Irina Overeem (USA), Thorsteinn Saemundsson (Iceland), Jeff Warburton (UK), Zbigniew Zwolinski (Poland). The central research question of this global group of scientists is to: Assess and model the contemporary sedimentary fluxes in cold climates, with emphasis on both particulate and dissolved components. Initially formed as European Science Foundation (ESF) Network SEDIFLUX (2004-2006), SEDIBUD has further expanded to a global group of researchers with field research sites located in polar and alpine regions in the northern and southern hemisphere. Research carried out at each of the close to 50 defined SEDIBUD key test sites varies by programme, logistics and available resources, but typically represent interdisciplinary collaborations of

  15. Field-Aligned Current Dynamics and Its Correlation with Solar Wind Conditions and Geomagnetic Activities From Space Technology 5 Observations

    NASA Astrophysics Data System (ADS)

    Wang, Yongli; Boardsen, Scott; Le, Guan; Slavin, James; Strangeway, Robert J.

    Field-aligned currents (FACs) are the currents flowing into and out of the ionosphere which connect to the magnetosphere. They provide an essential linkage between the solar wind - magnetosphere system and the ionosphere, and the understanding of these currents is important for global magnetosphere dynamics and space weather prediction. The three spacecraft ST-5 constellation provides an unprecedented opportunity to study in situ FAC dynamics in time scales (10 sec to 10 min) that can not be achieved previously with single spacecraft studies or large-spaced conjugate spacecraft studies. In this study, we use the magnetic field observations during the whole ST-5 mission to study the dependence of FAC current sheet motion and intensity on solar wind conditions. FAC peak current densities show very good correlations with some solar wind parameters, including IMF Bz, dynamic pressure, Ey, and some IMF angles, but not with other parameters. Instant FAC speeds show generally much weaker dependence on solar wind conditions comparing to FAC peak current densities. This obvious uncorrelation between FAC peak current densities and speeds implies that FAC peak current densities are more consistently controlled by solar wind conditions and geomagnetic activities, while FAC speeds are more oscillatory, sometimes with higher speeds during quieter times and lower speeds during more turbulent times. Detailed examination of FAC current sheet speed during two major storms in the ST-5 mission will also be given to illustrate the temporal evolution of the FAC dynamics with geomagnetic storm.

  16. Current radar-responsive tag development activities at Sandia National Laboratories

    NASA Astrophysics Data System (ADS)

    Ormesher, Richard C.; Plummer, Kenneth W.; Wells, Lars M.

    2004-08-01

    Over the past ten years, Sandia has developed RF radar responsive tag systems and supporting technologies for various government agencies and industry partners. RF tags can function as RF transmitters or radar transponders that enable tagging, tracking, and location determination functions. Expertise in tag architecture, microwave and radar design, signal analysis and processing techniques, digital design, modeling and simulation, and testing have been directly applicable to these tag programs. In general, the radar responsive tag designs have emphasized low power, small package size, and the ability to be detected by the radar at long ranges. Recently, there has been an interest in using radar responsive tags for Blue Force tracking and Combat ID (CID). The main reason for this interest is to allow airborne surveillance radars to easily distinguish U.S. assets from those of opposing forces. A Blue Force tracking capability would add materially to situational awareness. Combat ID is also an issue, as evidenced by the fact that approximately one-quarter of all U.S. casualties in the Gulf War took the form of ground troops killed by friendly fire. Because the evolution of warfare in the intervening decade has made asymmetric warfare the norm rather than the exception, swarming engagements in which U.S. forces will be freely intermixed with opposing forces is a situation that must be anticipated. Increasing utilization of precision munitions can be expected to drive fires progressively closer to engaged allied troops at times when visual de-confliction is not an option. In view of these trends, it becomes increasingly important that U.S. ground forces have a widely proliferated all-weather radar responsive tag that communicates to all-weather surveillance. The purpose of this paper is to provide an overview of the recent, current, and future radar responsive research and development activities at Sandia National Laboratories that support both the Blue Force Tracking

  17. The Europa Imaging System (EIS): Investigating Europa's geology, ice shell, and current activity

    NASA Astrophysics Data System (ADS)

    Turtle, Elizabeth; Thomas, Nicolas; Fletcher, Leigh; Hayes, Alexander; Ernst, Carolyn; Collins, Geoffrey; Hansen, Candice; Kirk, Randolph L.; Nimmo, Francis; McEwen, Alfred; Hurford, Terry; Barr Mlinar, Amy; Quick, Lynnae; Patterson, Wes; Soderblom, Jason

    2016-07-01

    NASA's Europa Mission, planned for launch in 2022, will perform more than 40 flybys of Europa with altitudes at closest approach as low as 25 km. The instrument payload includes the Europa Imaging System (EIS), a camera suite designed to transform our understanding of Europa through global decameter-scale coverage, topographic and color mapping, and unprecedented sub- meter-scale imaging. EIS combines narrow-angle and wide-angle cameras to address these science goals: • Constrain the formation processes of surface features by characterizing endogenic geologic structures, surface units, global cross-cutting relationships, and relationships to Europa's subsurface structure and potential near-surface water. • Search for evidence of recent or current activity, including potential plumes. • Characterize the ice shell by constraining its thickness and correlating surface features with subsurface structures detected by ice penetrating radar. • Characterize scientifically compelling landing sites and hazards by determining the nature of the surface at scales relevant to a potential lander. EIS Narrow-angle Camera (NAC): The NAC, with a 2.3°° x 1.2°° field of view (FOV) and a 10-μμrad instantaneous FOV (IFOV), achieves 0.5-m pixel scale over a 2-km-wide swath from 50-km altitude. A 2-axis gimbal enables independent targeting, allowing very high-resolution stereo imaging to generate digital topographic models (DTMs) with 4-m spatial scale and 0.5-m vertical precision over the 2-km swath from 50-km altitude. The gimbal also makes near-global (>95%) mapping of Europa possible at ≤50-m pixel scale, as well as regional stereo imaging. The NAC will also perform high-phase-angle observations to search for potential plumes. EIS Wide-angle Camera (WAC): The WAC has a 48°° x 24°° FOV, with a 218-μμrad IFOV, and is designed to acquire pushbroom stereo swaths along flyby ground-tracks. From an altitude of 50 km, the WAC achieves 11-m pixel scale over a 44-km

  18. Spatial and Statistical Evolution of Electrical Current Density in Active Region 12158 Producing an X-class Flare

    NASA Astrophysics Data System (ADS)

    Kang, Jihye; Magara, Tetsuya; Inoue, Satoshi; Kubo, Yuki; Nishizuka, Naoto

    2016-05-01

    The formation of a current sheet in the solar corona where an intense electric current flows is one of the important processes leading to the onset of a solar flare. In this work, we investigate the temporal development of the distribution of electric current density derived from a time series of nonlinear force-free (NLFF) fields in active region 12158 (AR12158) which produces an X-class flare on 2014 September 10. A preflare NLFF field, where an intense electric current flows, reproduces an observed inverse-S shaped sigmoidal structure. The statistical distribution of electric current density has a double power-law profile during the evolution of AR12158. We discuss several key parameters of the double power-law profile and the time variations in them, which might be used as a quantitative indicator of flare onset.

  19. Do Invertebrate Activity and Current Velocity Affect Fungal Assemblage Structure in Leaves?

    NASA Astrophysics Data System (ADS)

    Ferreira, Verónica; Graça, Manuel A. S.

    2006-02-01

    In this study we assessed the effect of current velocity and shredder presence, manipulated in artificial channels, on the structure of the fungal assemblage colonizing alder (Alnus glutinosa (L.) Gaertner) leaves incubated in coarse and fine mesh bags. Fungal sporulation rates, cumulative conidial production and number of species of aquatic hyphomycetes were higher in leaves exposed to high rather than to low current velocity. The opposite was observed regarding Simpson's index (D) on the fungal assemblage. Some species of aquatic hyphomycetes were consistently stimulated in high current channels. No effect of shredders or of mesh type was observed.

  20. PREVIMER : Meteorological inputs and outputs

    NASA Astrophysics Data System (ADS)

    Ravenel, H.; Lecornu, F.; Kerléguer, L.

    2009-09-01

    PREVIMER is a pre-operational system aiming to provide a wide range of users, from private individuals to professionals, with short-term forecasts about the coastal environment along the French coastlines bordering the English Channel, the Atlantic Ocean, and the Mediterranean Sea. Observation data and digital modelling tools first provide 48-hour (probably 96-hour by summer 2009) forecasts of sea states, currents, sea water levels and temperatures. The follow-up of an increasing number of biological parameters will, in time, complete this overview of coastal environment. Working in partnership with the French Naval Hydrographic and Oceanographic Service (Service Hydrographique et Océanographique de la Marine, SHOM), the French National Weather Service (Météo-France), the French public science and technology research institute (Institut de Recherche pour le Développement, IRD), the European Institute of Marine Studies (Institut Universitaire Européen de la Mer, IUEM) and many others, IFREMER (the French public institute fo marine research) is supplying the technologies needed to ensure this pertinent information, available daily on Internet at http://www.previmer.org, and stored at the Operational Coastal Oceanographic Data Centre. Since 2006, PREVIMER publishes the results of demonstrators assigned to limited geographic areas and to specific applications. This system remains experimental. The following topics are covered : Hydrodynamic circulation, sea states, follow-up of passive tracers, conservative or non-conservative (specifically of microbiological origin), biogeochemical state, primary production. Lastly, PREVIMER provides researchers and R&D departments with modelling tools and access to the database, in which the observation data and the modelling results are stored, to undertake environmental studies on new sites. The communication will focus on meteorological inputs to and outputs from PREVIMER. It will draw the lessons from almost 3 years during

  1. Coarse-grained simulations of the gating current in the voltage-activated Kv1.2 channel

    PubMed Central

    Kim, Ilsoo; Warshel, Arieh

    2014-01-01

    Quantitative structure-based modeling of voltage activation of ion channels is very challenging. For example, it is very hard to reach converging results, by microscopic simulations while macroscopic treatments involve major uncertainties regarding key features. The current work overcomes some of the above challenges by using our recently developed coarse-grained (CG) model in simulating the activation of the Kv1.2 channel. The CG model has allowed us to explore problems that cannot be fully addressed at present by microscopic simulations, while providing insights on some features that are not usually considered in continuum models, including the distribution of the electrolytes between the membrane and the electrodes during the activation process and thus the physical nature of the gating current. Here, we demonstrate that the CG model yields realistic gating charges and free energy landscapes that allow us to simulate the fluctuating gating current in the activation processes. Our ability to simulate the time dependence of the fast gating current allows us to reproduce the observed trend and provides a clear description of its relationship to the landscape involved in the activation process. PMID:24464485

  2. Using Active Video Games for Physical Activity Promotion: A Systematic Review of the Current State of Research

    ERIC Educational Resources Information Center

    Peng, Wei; Crouse, Julia C.; Lin, Jih-Hsuan

    2013-01-01

    This systematic review evaluates interventions using active video games (AVGs) to increase physical activity and summarizes laboratory studies quantifying intensity of AVG play among children and adults. Databases (Cochrane Library, PsychInfo, PubMed, SPORTDiscus, Web of Science) and forward citation and reference list searches were used to…

  3. 75 FR 28100 - Agency Information Collection Activities: Notice of Request for Extension of Currently Approved...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-19

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  4. 77 FR 52380 - Agency Information Collection Activities; Revision of a Currently-Approved Information Collection...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-29

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  5. 77 FR 75490 - Agency Information Collection Activities; Reinstatement With Change of a Currently-Approved...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-20

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    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-14

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  7. Thermally activated flux creep and critical current densities in high temperature superconductors

    NASA Astrophysics Data System (ADS)

    Matsushita, Teruo

    The effect of flux creep is discussed for projected strongly pinned oxide superconductors. It is determined, that if a superconducting wire with a critical current density higher than 10-billion A/sq m at 77 K and 5 T can be produced, the wire will be able to be applied to equipment at high fields; nonzero critical density will be obtained even at 77 K and high fields. The decay of persistent current is expected to be noticeable even in such strongly pinned superconductors, when those are used at 77 K. Although this will be managed in power equipment by lowering the operating current; variation in the magnetic field due to the variation in the current distribution inside superconducting wires appears to be unavoidable. It is suggested that an effort should be made to reduce the variation by reducing the diameter of the superconducting filaments.

  8. Effect of trimebutine on voltage-activated calcium current in rabbit ileal smooth muscle cells.

    PubMed

    Nagasaki, M; Komori, S; Ohashi, H

    1993-09-01

    1. The effect of trimebutine on the voltage-dependent inward Ca2+ current was investigated by the whole-cell voltage-clamp technique in single smooth muscle cells from rabbit ileum. 2. Trimebutine (3-100 microM) reduced the Ca2+ current in a concentration-dependent manner. The inhibitory effect on the Ca2+ current was also dependent on the holding potential. The Ca2+ current after a low holding potential was inhibited to a greater extent than that after a high membrane potential: the IC50 values were 7 microM and 36 microM at holding potentials of -40 mV and -60 mV, respectively. The Ca2+ current elicited from a holding potential of -80 mV could not be reduced by as much as 50% of the control by trimebutine at concentrations as high as 100 microM. 3. Trimebutine (30 microM) shifted the voltage-dependent inactivation curve for the Ca2+ current by 18 mV in the negative direction. The affinity of the drug for Ca2+ channels was calculated to be 36 times higher in the inactivated state than in the closed-available state. 4. Blockade of the Ca2+ current by trimebutine, unlike verapamil, was not use-dependent. 5. The results suggest that trimebutine inhibits the voltage-dependent inward Ca2+ current through a preferential binding to Ca2+ channels in the inactivated state in the smooth muscle cell from rabbit ileum. The inhibitory effect of trimebutine on gastrointestinal motility is discussed in the light of the present findings. PMID:8220900

  9. Anomalous neuronal responses to fluctuated inputs

    NASA Astrophysics Data System (ADS)

    Hosaka, Ryosuke; Sakai, Yutaka

    2015-10-01

    The irregular firing of a cortical neuron is thought to result from a highly fluctuating drive that is generated by the balance of excitatory and inhibitory synaptic inputs. A previous study reported anomalous responses of the Hodgkin-Huxley neuron to the fluctuated inputs where an irregularity of spike trains is inversely proportional to an input irregularity. In the current study, we investigated the origin of these anomalous responses with the Hindmarsh-Rose neuron model, map-based models, and a simple mixture of interspike interval distributions. First, we specified the parameter regions for the bifurcations in the Hindmarsh-Rose model, and we confirmed that the model reproduced the anomalous responses in the dynamics of the saddle-node and subcritical Hopf bifurcations. For both bifurcations, the Hindmarsh-Rose model shows bistability in the resting state and the repetitive firing state, which indicated that the bistability was the origin of the anomalous input-output relationship. Similarly, the map-based model that contained bistability reproduced the anomalous responses, while the model without bistability did not. These results were supported by additional findings that the anomalous responses were reproduced by mimicking the bistable firing with a mixture of two different interspike interval distributions. Decorrelation of spike trains is important for neural information processing. For such spike train decorrelation, irregular firing is key. Our results indicated that irregular firing can emerge from fluctuating drives, even weak ones, under conditions involving bistability. The anomalous responses, therefore, contribute to efficient processing in the brain.

  10. Anomalous neuronal responses to fluctuated inputs.

    PubMed

    Hosaka, Ryosuke; Sakai, Yutaka

    2015-10-01

    The irregular firing of a cortical neuron is thought to result from a highly fluctuating drive that is generated by the balance of excitatory and inhibitory synaptic inputs. A previous study reported anomalous responses of the Hodgkin-Huxley neuron to the fluctuated inputs where an irregularity of spike trains is inversely proportional to an input irregularity. In the current study, we investigated the origin of these anomalous responses with the Hindmarsh-Rose neuron model, map-based models, and a simple mixture of interspike interval distributions. First, we specified the parameter regions for the bifurcations in the Hindmarsh-Rose model, and we confirmed that the model reproduced the anomalous responses in the dynamics of the saddle-node and subcritical Hopf bifurcations. For both bifurcations, the Hindmarsh-Rose model shows bistability in the resting state and the repetitive firing state, which indicated that the bistability was the origin of the anomalous input-output relationship. Similarly, the map-based model that contained bistability reproduced the anomalous responses, while the model without bistability did not. These results were supported by additional findings that the anomalous responses were reproduced by mimicking the bistable firing with a mixture of two different interspike interval distributions. Decorrelation of spike trains is important for neural information processing. For such spike train decorrelation, irregular firing is key. Our results indicated that irregular firing can emerge from fluctuating drives, even weak ones, under conditions involving bistability. The anomalous responses, therefore, contribute to efficient processing in the brain. PMID:26565270

  11. Nonlinear input-output systems

    NASA Technical Reports Server (NTRS)

    Hunt, L. R.; Luksic, Mladen; Su, Renjeng

    1987-01-01

    Necessary and sufficient conditions that the nonlinear system dot-x = f(x) + ug(x) and y = h(x) be locally feedback equivalent to the controllable linear system dot-xi = A xi + bv and y = C xi having linear output are found. Only the single input and single output case is considered, however, the results generalize to multi-input and multi-output systems.

  12. Regulatory role of tyrosine phosphorylation in the swelling-activated chloride current in isolated rabbit articular chondrocytes.

    PubMed

    Okumura, Noriaki; Imai, Shinji; Toyoda, Futoshi; Isoya, Eiji; Kumagai, Kousuke; Matsuura, Hiroshi; Matsusue, Yoshitaka

    2009-08-01

    Articular chondrocytes are exposed in vivo to the continually changing osmotic environment and thus require volume regulatory mechanisms. The present study was designed to investigate (i) the functional role of the swelling-activated Cl(-) current (I(Cl,swell)) in the regulatory volume decrease (RVD) and (ii) the regulatory role of tyrosine phosphorylation in I(Cl,swell), in isolated rabbit articular chondrocytes. Whole-cell membrane currents were recorded from chondrocytes in isosmotic, hyposmotic and hyperosmotic external solutions under conditions where Na(+), K(+) and Ca(2+) currents were minimized. The cell surface area was also measured using microscope images from a separate set of chondrocytes and was used as an index of cell volume. The isolated chondrocytes exhibited a RVD during sustained exposure to hyposmotic solution, which was mostly inhibited by the I(Cl,swell) blocker 4-(2-butyl-6,7-dichloro-2-cyclopentyl-indan-1-on-5-yl)oxobutyric acid (DCPIB) at 20 microM. Exposure to a hyposmotic solution activated I(Cl,swell), which was also largely inhibited by 20 microM DCPIB. I(Cl,swell) in rabbit articular chondrocytes had a relative taurine permeability (P(tau)/P(Cl)) of 0.21. Activation of I(Cl,swell) was significantly reduced by the protein tyrosine kinase (PTK) inhibitor genistein (30 microM) but was only weakly affected by its inactive analogue daidzein (30 microM). Intracellular application of protein tyrosine phosphatase (PTP) inhibitor sodium orthovanadate (250 and 500 microM) resulted in a gradual activation of a Cl(-) current even in isosmotic solutions. This Cl(-) current was almost completely inhibited by 4,4-diisothiocyanatostilbene-2,2-disulfonate (DIDS, 500 microM) and was also largely suppressed by exposure to hyperosmotic solution, thus indicating a close similarity to I(Cl,swell). Pretreatment of chondrocytes with genistein significantly prevented the activation of the Cl(-) current by sodium orthovanadate, suggesting that the basal

  13. A survey of radiation treatment planning peer-review activities in a provincial radiation oncology programme: current practice and future directions

    PubMed Central

    Brundage, Michael; Foxcroft, Sophie; McGowan, Tom; Gutierrez, Eric; Sharpe, Michael; Warde, Padraig

    2013-01-01

    Objectives To describe current patterns of practice of radiation oncology peer review within a provincial cancer system, identifying barriers and facilitators to its use with the ultimate aim of process improvement. Design A survey of radiation oncology programmes at provincial cancer centres. Setting All cancer centres within the province of Ontario, Canada (n=14). These are community-based outpatient facilities overseen by Cancer Care Ontario, the provincial cancer agency. Participants A delegate from each radiation oncology programme filled out a single survey based on input from their multidisciplinary team. Outcome measures Rated importance of peer review; current utilisation; format of the peer-review process; organisation and timing; case attributes; outcomes of the peer-review process and perceived barriers and facilitators to expanding peer-review processes. Results 14 (100%) centres responded. All rated the importance of peer review as at least 8/10 (10=extremely important). Detection of medical error and improvement of planning processes were the highest rated perceived benefits of peer review (each median 9/10). Six centres (43%) reviewed at least 50% of curative cases; four of these centres (29%) conducted peer review in more than 80% of cases treated with curative intent. Fewer than 20% of cases treated with palliative intent were reviewed in most centres. Five centres (36%) reported usually conducting peer review prior to the initiation of treatment. Five centres (36%) recorded the outcomes of peer review on the medical record. Thirteen centres (93%) planned to expand peer-review activities; a critical mass of radiation oncologists was the most important limiting factor (median 6/10). Conclusions Radiation oncology peer-review practices can vary even within a cancer system with provincial oversight. The application of guidelines and standards for peer-review processes, and monitoring of implementation and outcomes, will require effective knowledge

  14. NON-NEUTRALIZED ELECTRIC CURRENT PATTERNS IN SOLAR ACTIVE REGIONS: ORIGIN OF THE SHEAR-GENERATING LORENTZ FORCE

    SciTech Connect

    Georgoulis, Manolis K.; Titov, Viacheslav S.; Mikic, Zoran

    2012-12-10

    Using solar vector magnetograms of the highest available spatial resolution and signal-to-noise ratio, we perform a detailed study of electric current patterns in two solar active regions (ARs): a flaring/eruptive and a flare-quiet one. We aim to determine whether ARs inject non-neutralized (net) electric currents in the solar atmosphere, responding to a debate initiated nearly two decades ago that remains inconclusive. We find that well-formed, intense magnetic polarity inversion lines (PILs) within ARs are the only photospheric magnetic structures that support significant net current. More intense PILs seem to imply stronger non-neutralized current patterns per polarity. This finding revises previous works that claim frequent injections of intense non-neutralized currents by most ARs appearing in the solar disk but also works that altogether rule out injection of non-neutralized currents. In agreement with previous studies, we also find that magnetically isolated ARs remain globally current-balanced. In addition, we confirm and quantify the preference of a given magnetic polarity to follow a given sense of electric currents, indicating a dominant sense of twist in ARs. This coherence effect is more pronounced in more compact ARs with stronger PILs and must be of sub-photospheric origin. Our results yield a natural explanation of the Lorentz force, invariably generating velocity and magnetic shear along strong PILs, thus setting a physical context for the observed pre-eruption evolution in solar ARs.

  15. Characterization of microbial content of organic and conventional produce in Maryland relative to production practices and inputs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Production inputs/practices such as soil amendments, water quality, animal intrusion, and human activity can influence microbial quality of fresh produce. Limited data on production practices relative to microbial/pathogen content of fresh produce are currently available for either org...

  16. Reduced Hyperpolarization-Activated Current Contributes to Enhanced Intrinsic Excitability in Cultured Hippocampal Neurons from PrP−/− Mice

    PubMed Central

    Fan, Jing; Stemkowski, Patrick L.; Gandini, Maria A.; Black, Stefanie A.; Zhang, Zizhen; Souza, Ivana A.; Chen, Lina; Zamponi, Gerald W.

    2016-01-01

    Genetic ablation of cellular prion protein (PrPC) has been linked to increased neuronal excitability and synaptic activity in the hippocampus. We have previously shown that synaptic activity in hippocampi of PrP-null mice is increased due to enhanced N-methyl-D-aspartate receptor (NMDAR) function. Here, we focused on the effect of PRNP gene knock-out (KO) on intrinsic neuronal excitability, and in particular, the underlying ionic mechanism in hippocampal neurons cultured from P0 mouse pups. We found that the absence of PrPC profoundly affected the firing properties of cultured hippocampal neurons in the presence of synaptic blockers. The membrane impedance was greater in PrP-null neurons, and this difference was abolished by the hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blocker ZD7288 (100 μM). HCN channel activity appeared to be functionally regulated by PrPC. The amplitude of voltage sag, a characteristic of activating HCN channel current (Ih), was decreased in null mice. Moreover, Ih peak current was reduced, along with a hyperpolarizing shift in activation gating and slower kinetics. However, neither HCN1 nor HCN2 formed a biochemical complex with PrPC. These results suggest that the absence of PrP downregulates the activity of HCN channels through activation of a cell signaling pathway rather than through direct interactions. This in turn contributes to an increase in membrane impedance to potentiate neuronal excitability. PMID:27047338

  17. Participation of a persistent sodium current and calcium-activated nonspecific cationic current to burst generation in trigeminal principal sensory neurons.

    PubMed

    Tsuruyama, Kentaro; Hsiao, Chie-Fang; Chandler, Scott H

    2013-10-01

    The properties of neurons participating in masticatory rhythmogenesis are not clearly understood. Neurons within the dorsal trigeminal principal sensory nucleus (dPrV) are potential candidates as components of the masticatory central pattern generator (CPG). The present study examines in detail the ionic mechanisms controlling burst generation in dPrV neurons in rat (postnatal day 8-12) brain stem slices using whole cell and perforated patch-clamp methods. Nominal extracellular Ca(2+) concentration transformed tonic discharge in response to a maintained step pulse of current into rhythmical bursting in 38% of nonbursting neurons. This change in discharge mode was suppressed by riluzole, a persistent Na(+) current (INaP) antagonist. Veratridine, which suppresses the Na(+) channel inactivation mechanism, induced rhythmical bursting in nonbursting neurons in normal artificial cerebrospinal fluid, suggesting that INaP contributes to burst generation. Nominal extracellular Ca(2+) exposed a prominent afterdepolarizing potential (ADP) following a single spike induced by a 3-ms current pulse, which was suppressed, but not completely blocked, by riluzole. Application of BAPTA, a Ca(2+) chelator, intracellularly, or flufenamic acid, a Ca(2+)-activated nonspecific cationic channel (ICAN) antagonist, extracellularly to the bath, suppressed rhythmical bursting and the postspike ADP. Application of drugs to alter Ca(2+) release from endoplasmic reticulum also suppressed bursting. Finally, voltage-clamp methods demonstrated that nominal Ca(2+) facilitated INaP and induced ICAN. These data demonstrate for the first time that the previously observed induction in dPrV neurons of rhythmical bursting in nominal Ca(2+) is mediated by enhancement of INaP and onset of ICAN, which are dependent on intracellular Ca(2+). PMID:23883859

  18. Temporal Dynamics of L5 Dendrites in Medial Prefrontal Cortex Regulate Integration Versus Coincidence Detection of Afferent Inputs

    PubMed Central

    Zemelman, Boris V.; Johnston, Daniel

    2015-01-01

    Distinct brain regions are highly interconnected via long-range projections. How this inter-regional communication occurs depends not only upon which subsets of postsynaptic neurons receive input, but also, and equally importantly, upon what cellular subcompartments the projections target. Neocortical pyramidal neurons receive input onto their apical dendrites. However, physiological characterization of these inputs thus far has been exclusively somatocentric, leaving how the dendrites respond to spatial and temporal patterns of input unexplored. Here we used a combination of optogenetics with multisite electrode recordings to simultaneously measure dendritic and somatic responses to afferent fiber activation in two different populations of layer 5 (L5) pyramidal neurons in the rat medial prefrontal cortex (mPFC). We found that commissural inputs evoked monosynaptic responses in both intratelencephalic (IT) and pyramidal tract (PT) dendrites, whereas monosynaptic hippocampal input primarily targeted IT, but not PT, dendrites. To understand the role of dendritic integration in the processing of long-range inputs, we used dynamic clamp to simulate synaptic currents in the dendrites. IT dendrites functioned as temporal integrators that were particularly responsive to dendritic inputs within the gamma frequency range (40–140 Hz). In contrast, PT dendrites acted as coincidence detectors by responding to spatially distributed signals within a narrow time window. Thus, the PFC extracts information from different brain regions through the combination of selective dendritic targeting and the distinct dendritic physiological properties of L5 pyramidal dendrites. PMID:25788669

  19. Current California legislative and regulatory activity impacting geothermal hydrothermal commercialization: monitoring report No. 2. Report No. 1020

    SciTech Connect

    Not Available

    1980-04-20

    The progress of four bills relating to geothermal energy is reported. The current regulatory activities of the California Energy Commission, the Lake County Planning Commission/Lake County Air Pollution Control District, the Governor's Office of Planning and Research, the State Lands' Commission, and the California Public Utilities Commission are reviewed. (MHR)

  20. Polarization features of solar radio emission and possible existence of current sheets in active regions

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Zheleznyakov, V. V.; White, S. M.; Kundu, M. R.

    1994-01-01

    We show that it is possible to account for the polarization features of solar radio emission provided the linear mode coupling theory is properly applied and the presence of current sheets in the corona is taken into account. We present a schematic model, including a current sheet that can explain the polarization features of both the low frequency slowly varying component and the bipolar noise storm radiation; the two radiations face similar propagation conditions through a current sheet and hence display similar polarization behavior. We discuss the applications of the linear mode coupling theory to the following types of solar emission: the slowly varying component, the microwave radio bursts, metric type U bursts, and bipolar noise storms.

  1. Fraternity Hazing Revisited: Current Alumni and Active Member Attitudes Toward Hazing.

    ERIC Educational Resources Information Center

    Baier, John L.; Williams, Patrick S.

    1983-01-01

    Studied hazing practices at a large university and compared active and alumni fraternity members' (N=259) attitudes towards them. Results showed alumni accepted hazing more than active members. Most members believed hazing served a valuable purpose and did not create problems in their own chapter. (WAS)

  2. Current Situation and Analysis of Geography Teachers' Active Learning Knowledge and Usage in Turkey

    ERIC Educational Resources Information Center

    Tuna, Fikret

    2012-01-01

    In parallel to the developments in the approach to education, the secondary education geography curriculum in Turkey was renewed in 2005. This new programme encourages the use of active learning methods and techniques in the classroom by adopting the idea that students should construct and interpret knowledge by actively participating in the…

  3. 75 FR 57467 - Agency Information Collection Activities: Renewal of Currently Approved Collection (3064-0137...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-21

    ... on the renewal of an existing information collection, as required by the PRA. On July 1, 2010 (75 FR... collection: Interagency Guidance on Asset Securitization Activities. (OMB No. 3064-0137). No comments were... Securitization Activities. OMB Number: 3064-0137. Form Number: None. Frequency of Response: On occasion....

  4. Turn customer input into innovation.

    PubMed

    Ulwick, Anthony W

    2002-01-01

    It's difficult to find a company these days that doesn't strive to be customer-driven. Too bad, then, that most companies go about the process of listening to customers all wrong--so wrong, in fact, that they undermine innovation and, ultimately, the bottom line. What usually happens is this: Companies ask their customers what they want. Customers offer solutions in the form of products or services. Companies then deliver these tangibles, and customers just don't buy. The reason is simple--customers aren't expert or informed enough to come up with solutions. That's what your R&D team is for. Rather, customers should be asked only for outcomes--what they want a new product or service to do for them. The form the solutions take should be up to you, and you alone. Using Cordis Corporation as an example, this article describes, in fine detail, a series of effective steps for capturing, analyzing, and utilizing customer input. First come indepth interviews, in which a moderator works with customers to deconstruct a process or activity in order to unearth "desired outcomes." Addressing participants' comments one at a time, the moderator rephrases them to be both unambiguous and measurable. Once the interviews are complete, researchers then compile a comprehensive list of outcomes that participants rank in order of importance and degree to which they are satisfied by existing products. Finally, using a simple mathematical formula called the "opportunity calculation," researchers can learn the relative attractiveness of key opportunity areas. These data can be used to uncover opportunities for product development, to properly segment markets, and to conduct competitive analysis. PMID:12964470

  5. Calcium-activated chloride channels do not contribute to the odorant transduction current in the marine teleost Isacia conceptionis.

    PubMed

    Osorio, R; Schmachtenberg, O

    2013-11-01

    This study compared the contribution of the Ca²⁺-activated Cl⁻ conductance to the electroolfactogram (EOG) evoked by different odorant classes between the marine Cabinza grunt Isacia conceptionis and rainbow trout Oncorhynchus mykiss. The Ca²⁺-activated Cl⁻ channel blocker niflumic acid significantly diminished odorant responses in O. mykiss, but had no effect on the EOG in I. conceptionis, supporting the notion that Ca²⁺-activated Cl⁻ channels may not operate as odorant transduction current amplifiers in this marine teleost. PMID:24580677

  6. Characterization of inhibition by haloperidol and chlorpromazine of a voltage-activated K+ current in rat phaeochromocytoma cells.

    PubMed Central

    Nakazawa, K.; Ito, K.; Koizumi, S.; Ohno, Y.; Inoue, K.

    1995-01-01

    1. Inhibition by haloperidol and chlorpromazine of a voltage-activated K+ current was characterized in rat phaeochromocytoma PC12 cells by use of whole-cell voltage-clamp techniques. 2. Haloperidol or chlorpromazine (1 and 10 microM) inhibited a K+ current activated by a test potential of +20 mV applied from a holding potential of -60 mV. The K+ current inhibition did not exhibit voltage-dependence when test potentials were changed between -10 and +40 mV or when holding potentials were changed between -120 and -60 mV. 3. Effects of compounds that are related to haloperidol and chlorpromazine in their pharmacological actions were examined. Fluspirilene (1 and 10 microM), an antipsychotic drug, inhibited the K+ current, but pimozide (1 and 10 microM), another antipsychotic drug did not significantly inhibit the K+ current. Sulpiride (1 or 10 microM), an antagonist of dopamine D2 receptors, did not affect the K+ current whereas (+)-SCH-23390 (10 microM), an antagonist of dopamine D1 receptors, reduced the K+ current. As for calmodulin antagonists, W-7 (100 microM), but not calmidazolium (1 microM), reduced the K+ current. 4. The inhibition by haloperidol or chlorpromazine of the K+ current was abolished when GTP in intracellular solution was replaced with GDP beta S. Similarly, the inhibition by pimozide, fluspirilene, (+)-SCH-23390 or W-7 was abolished or attenuated in the presence of intracellular GDP beta S. The inhibition by haloperidol or chlorpromazine was not prevented when cells were pretreated with pertussis toxin or when K-252a, an inhibitor of a variety of protein kinases, was included in the intracellular solution. 5. Haloperidol and chlorpromazine reduced a Ba2+ current permeating through Ca2+ channels. Inhibition by haloperidol or chlorpromazine of the Ba2+ current was not affected by GDP beta S included in the intracellular solution. 6. It is concluded that haloperidol and chlorpromazine inhibit voltage-gated K+ channels in PC12 cells by a mechanism

  7. High effectiveness of triptolide, an active diterpenoid triepoxide, in suppressing Kir-channel currents from human glioma cells.

    PubMed

    So, Edmund Cheung; Lo, Yi-Ching; Chen, Li-Tzong; Kao, Chin-An; Wu, Sheng-Nan

    2014-09-01

    Triptolide (Trip), a diterpene triepoxide isolated from medicinal vine Trypterygium wilfordii Hook. F. possessed multiple biological activities including antineoplastic actions. However, no report concerning its effects on ion currents has been published. In this study, we attempted to determine whether this compound has any effects on ion currents in malignant glioma cells. The mRNA expression of KCNJ10 (Kir4.1) was detected in U373 glioma cells. The inwardly rectifying K(+) currents (IK(IR)) in U373 cells were almost fully blocked by BaCl2 (1mM). Trip (30 nM-10 μM) effectively decreased the amplitude of IK(IR) in a concentration-dependent manner with an IC50 value of 0.72 μM. In chlorotoxin-treated U373 cells, Trip-mediated block of IK(IR) remained effective. Addition of Trip (3 μM) slightly inhibited the amplitude of Ca(2+)-activated K(+) current and sustained K(+) outward current in U373 cells. In cell-attached configuration, when Trip was added to the bath, the activity of inwardly rectifying K(+) (Kir) channels diminished with no change in single-channel conductance. Its suppression of Kir channels was accompanied by a reduction in the slow component of mean open time. Under current-clamp conditions, addition of Trip depolarized the membrane along with changes in frequency histogram of resting potential. Block by this component of Kir4.1 channels may be an important mechanism underlying its actions on the functional activity of glioma cells. Targeting at Kir4.1 channels may be clinically useful as an adjunctive regimen to anti-cancer drugs. PMID:24927992

  8. 77 FR 22333 - Agency Information Collection Activities: USCIS Case Status Online, Extension of a Currently...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-13

    ... Federal Register on January 30, 2012, at 77 FR 4574, allowing for a 60- day public comment period. USCIS... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HOMELAND... Status Online, Extension of a Currently Approved Information Collection; Comment Request ACTION:...

  9. 76 FR 77817 - Agency Information Collection Activities; Proposed Renewal of Several Currently Approved...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-14

    ...In compliance with the Paperwork Reduction Act (PRA) (44 U.S.C. 3501 et seq.), this document announces that EPA is planning to submit requests to renew several currently approved Information Collection Request (ICR) to the Office of Management and Budget (OMB). The ICRs are specifically identified in this document by their corresponding titles, EPA ICR numbers, OMB Control numbers, and related......

  10. 75 FR 44837 - Agency Information Collection Activities: Notice of Request for Extension of Currently Approved...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-29

    ... Fellowship Program OMB Control #: 2125-0617. Background: The Eisenhower Transportation Fellowship Program is comprised of two programs, the Eisenhower Transportation Fellowship and the National Highway Institute (NHI). The Eisenhower Transportation Fellowship is currently authorized by Public Law 109-59, the...

  11. 75 FR 22843 - Agency Information Collection Activities: Revision of a Currently Approved Collection; Comments...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-30

    ... Currently Approved Collection 2009 Census of Publicly Funded Forensic Crime Laboratories. The Department of... approved collection. ] (2) Title of the Form/Collection: 2009 Census of Publicly Funded Forensic Crime... information collection is a census of public crime laboratories that perform forensic analyses on...

  12. External current application in a bidomain model of active neural tissue.

    PubMed

    Keim, Steven F; Fu, Fanrui; Sadleir, Rosalind J

    2015-08-01

    The formal treatment of tissue as two coupled continua is referred to as a bidomain model. Bidomain models have recently been used to describe the properties of neural tissue and nerve fiber bundles [1, 2]. By adapting the Hodgkin Huxley equations in COMSOL Multiphysics, we have investigated the propagation of an action potential through neural tissue by external current stimulation. PMID:26736753

  13. Consolidation of binderless nanostructured TiC by pulsed current activated sintering and its mechanical properties.

    PubMed

    Shon, In-Jin; Kim, Byung-Ryang; Ko, In-Yong; Doh, Jung-Mann; Yoon, Jin-Kook

    2011-02-01

    A dense nanostructured TiC with a relative density of up to 98% was produced with simultaneous application of 80 MPa pressure and pulsed current of 2800 A using the nanopowder of TiC. The effect of the ball milling times on the sintering behavior, grain size and mechanical properties of binderless TiC was investigated. PMID:21456219

  14. 75 FR 40840 - Agency Information Collection Activities; Proposed Collection; Comment Request; Current Good...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-14

    ... Register of June 25, 2007 (72 FR 34752) (the June 25, 2007, final rule) FDA published a final rule that... Collection; Comment Request; Current Good Manufacturing Practice in Manufacturing, Packaging, Labeling, or..., Packaging, Labeling, or Holding Operations for Dietary Supplements--21 CFR Part 111 (OMB Control Number...

  15. 78 FR 76836 - Agency Information Collection Activities; Proposed Collection; Comment Request; Current Good...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-19

    ... enforcement of the FD&C Act. In the Federal Register of June 25, 2007 (72 FR 34752) (the June 25, 2007, final... Collection; Comment Request; Current Good Manufacturing Practice in Manufacturing, Packaging, Labeling, or..., Packaging, Labeling, or Holding Operations for Dietary Supplements--21 CFR Part 111 (OMB Control Number...

  16. Cumulative Risk Assessment: Overview of Agency Guidance, Practice and Current Major Research Activities

    EPA Science Inventory

    Powerpoint presentation that includes the EPA's definition of CRA, relevant publications already in existence, the CRA Guidelines effort, science issues where research is still needed, program office practices related to CRA, and EPA research activities.

  17. 75 FR 77940 - Agency Information Collection Activities; Extension of a Currently-Approved Information...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-14

    ... Federal Motor Carrier Safety Administration Agency Information Collection Activities; Extension of a... AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Notice and request for comments... identify designated/restricted routes and restrictions or limitations affecting how motor carriers...

  18. Persistent currents and discharge patterns in rat hindlimb motoneurons.

    PubMed

    Hamm, Thomas M; Turkin, Vladimir V; Bandekar, Neha K; O'Neill, Derek; Jung, Ranu

    2010-09-01

    We report here the first direct measurements of persistent inward currents (PICs) in rat hindlimb motoneurons, obtained from ketamine-xylazine anesthetized rats during slow voltage ramps performed by single-electrode somatic voltage clamp. Most motoneurons expressed PICs and current-voltage (I-V) relations often contained a negative-slope region (NSR; 13/19 cells). PICs activated at -52.7 ± 3.89 mV, 9 mV negative to spike threshold. NSR onset was -44.2 ± 4.1 mV. PIC amplitudes were assessed by maximum inward currents measured relative to extrapolated leak current and to NSR-onset current. PIC conductance at potentials just positive to activation was assessed by the relative change in slope conductance (g(in)/g(leak)). PIC amplitudes varied widely; some exceeded 5 and 10 nA relative to current at NSR onset or leak current, respectively. PIC amplitudes did not vary significantly with input conductance, but PIC amplitudes normalized by recruitment current decreased with increasing input conductance. Similarly, g(in)/g(leak) decreased with increasing input conductance. Currents near resting potential on descending limbs of I-V relations were often outward, relative to ascending-limb currents. This residual outward current was correlated with increases in leak conductance on the descending limb and with input conductance. Excluding responses with accommodation, residual outward currents matched differences between recruitment and derecruitment currents, suggesting a role for residual outward current in frequency adaptation. Comparison of potentials for PIC activation and NSR onset with interspike trajectories during discharge demonstrated correspondence between PIC activation and frequency-current (f-I) range boundaries. Contributions of persistent inward and outward currents to motoneuron discharge characteristics are discussed. PMID:20592117

  19. Model Vestibular Nuclei Neurons Can Exhibit a Boosting Nonlinearity Due to an Adaptation Current Regulated by Spike-Triggered Calcium and Calcium-Activated Potassium Channels

    PubMed Central

    Schneider, Adam D.

    2016-01-01

    In vitro studies have previously found a class of vestibular nuclei neurons to exhibit a bidirectional afterhyperpolarization (AHP) in their membrane potential, due to calcium and calcium-activated potassium conductances. More recently in vivo studies of such vestibular neurons were found to exhibit a boosting nonlinearity in their input-output tuning curves. In this paper, a Hodgkin-Huxley (HH) type neuron model, originally developed to reproduce the in vitro AHP, is shown to produce a boosting nonlinearity similar to that seen in vivo for increased the calcium conductance. Indicative of a bifurcation, the HH model is reduced to a generalized integrate-and-fire (IF) model that preserves the bifurcation structure and boosting nonliearity. By then projecting the neuron model’s phase space trajectories into 2D, the underlying geometric mechanism relating the AHP and boosting nonlinearity is revealed. Further simplifications and approximations are made to derive analytic expressions for the steady steady state firing rate as a function of bias current, μ, as well as the gain (i.e. its slope) and the position of its peak at μ = μ*. Finally, although the boosting nonlinearity has not yet been experimentally observed in vitro, testable predictions indicate how it might be found. PMID:27427914

  20. Automatic seizure detection based on the activity of a set of current dipoles: first steps.

    PubMed

    Gritsch, G; Hartmann, M; Perko, H; Fürbaß, F; Kluge, T

    2012-01-01

    In this paper we show advantages of using an advanced montage scheme with respect to the performance of automatic seizure detection systems. The main goal is to find the best performing montage scheme for our automatic seizure detection system. The new virtual montage is a fix set of dipoles within the brain. The current density signals for these dipoles are derived from the scalp EEG signals based on a smart linear transformation. The reason for testing an alternative approach is that traditional montages (reference, bipolar) have some limitations, e.g. the detection performance depends on the choice of the reference electrode and an extraction of spatial information is often demanding. In this paper we explain the detailed setup of how to adapt a modern seizure detection system to use current density signals. Furthermore, we show results concerning the detection performance of different montage schemes and their combination. PMID:23366519

  1. Simulation of the bursting activity of neuron R15 in Aplysia: role of ionic currents, calcium balance, and modulatory transmitters.

    PubMed

    Canavier, C C; Clark, J W; Byrne, J H

    1991-12-01

    1. An equivalent circuit model of the R15 bursting neuron in Aplysia has been combined with a fluid compartment model, resulting in a model that incorporates descriptions of most of the membrane ion channels that are known to exist in the somata of R15, as well as providing a Ca2+ balance on the cell. 2. A voltage-activated, calcium-inactivated Ca2+ current (denoted the slow inward current ISI) was sufficient to produce bursting activity without invoking any other calcium-dependent currents (such as a nonspecific cation current, INS, or a calcium-activated K+ current, IK,Ca). Furthermore, many characteristics of a typical R15 burst could be simulated, such as a parabolic variation in interspike interval, the depolarizing afterpotential (DAP), and the progressive decrease in the undershoots of spikes during a burst. 3. The dynamic activity of R15 was analyzed by separately characterizing two different temporal domains; the fast dynamics associated with action potentials and the slow dynamics associated with low-amplitude oscillations lasting tens of seconds ("slow waves"). The slow dynamics were isolated by setting the Na+ conductance (gNa) to zero and then studied by the use of a system of equations reduced to two variables: intracellular concentration of Ca2+ and membrane potential. The fixed point of the system was located at the intersection of the nullclines for these two variables. A stability analysis of the fixed point was then used to determine whether a given set of parameters would produce slow-wave activity. 4. If the reduced model predicted slow-wave oscillations for a given set of parameters with gNa set to zero, then bursting activity was observed for the same set of parameters in the full model with gNa reset to its control value. However, for certain sets of parameters with gNa at its usual value, the full model exhibited bursting activity because of a slow oscillation produced by the activation of INS by action potentials. This oscillation resulted

  2. Input Type and Parameter Resetting: Is Naturalistic Input Necessary?

    ERIC Educational Resources Information Center

    Rothman, Jason; Iverson, Michael

    2007-01-01

    It has been argued that extended exposure to naturalistic input provides L2 learners with more of an opportunity to converge of target morphosyntactic competence as compared to classroom-only environments, given that the former provide more positive evidence of less salient linguistic properties than the latter (e.g., Isabelli 2004). Implicitly,…

  3. ASIC-like Currents in Freshly Isolated Cerebral Artery Smooth Muscle Cells are Inhibited by Endogenous Oxidase Activity

    PubMed Central

    Chung, Wen-Shuo; Farley, Jerry M.; Drummond, Heather A.

    2011-01-01

    Background/Aims: The aim of this study was to determine if VSMC ASIC-like currents are regulated by oxidative state. Methods: We used whole-cell patch clamp of isolated mouse cerebral VSMCs to determine if 1) reducing agents, such as DTT and GSH, and 2) inhibition of endogenous oxidase activity from NADPH and Xanthine oxidases potentiate active currents and activate electrically silent currents. Results: Pretreatment with 2 mM DTT or GSH, increased the mean peak amplitude of ASIC-like currents evoked by pH 6.0 from 0.4 ± 0.1 to 14.9 ± 3.6 pA/pF, and from 0.9 ± 0.3 to 11.3 ± 2.4 pA/pF, respectively. Pretreatment with apocynin, a NADPH oxidase inhibitor, mimics the effect of the reducing agents, with the mean peak current amplitude increased from 0.9 ± 0.5 to 7.0 ± 2.6 pA/pF and from 0.5 ± 0.2 to 26.4 ± 6.8 pA/pF by 50 and 200 μM apocynin, respectively. Pretreatment with allopurinol, a xanthine oxidase inhibitor, also potentiates the VSMC ASIC-like activity. Conclusion: These findings suggest that VSMC ASIC-like channels are regulated by oxidative state and may be inhibited by basal endogenous oxidative sources such as NADPH and xanthine oxidase. PMID:21325830

  4. Spinal direct current stimulation modulates the activity of gracile nucleus and primary somatosensory cortex in anaesthetized rats

    PubMed Central

    Aguilar, J; Pulecchi, F; Dilena, R; Oliviero, A; Priori, A; Foffani, G

    2011-01-01

    Abstract Afferent somatosensory activity from the spinal cord has a profound impact on the activity of the brain. Here we investigated the effects of spinal stimulation using direct current, delivered at the thoracic level, on the spontaneous activity and on the somatosensory evoked potentials of the gracile nucleus, which is the main entry point for hindpaw somatosensory signals reaching the brain from the dorsal columns, and of the primary somatosensory cortex in anaesthetized rats. Anodal spinal direct current stimulation (sDCS) increased the spontaneous activity and decreased the amplitude of evoked responses in the gracile nucleus, whereas cathodal sDCS produced the opposite effects. At the level of the primary somatosensory cortex, the changes in spontaneous activity induced by sDCS were consistent with the effects observed in the gracile nucleus, but the changes in cortical evoked responses were more variable and state dependent. Therefore, sDCS can modulate in a polarity-specific manner the supraspinal activity of the somatosensory system, offering a versatile bottom-up neuromodulation technique that could potentially be useful in a number of clinical applications. PMID:21825031

  5. Anesthetic activation of central respiratory chemoreceptor neurons involves inhibition of a THIK-1-like background K+ current

    PubMed Central

    Lazarenko, Roman M.; Fortuna, Michal G.; Shi, Yingtang; Mulkey, Daniel K.; Takakura, Ana C.; Moreira, Thiago S.; Guyenet, Patrice G.; Bayliss, Douglas A.

    2010-01-01

    At surgical depths of anesthesia, inhalational anesthetics cause a loss of motor response to painful stimuli (i.e., immobilization) that is characterized by profound inhibition of spinal motor circuits. Yet, although clearly depressed, the respiratory motor system continues to provide adequate ventilation under these same conditions. Here, we show that isoflurane causes robust activation of CO2/pH-sensitive, Phox2b-expressing neurons located in the retrotrapezoid nucleus (RTN) of the rodent brainstem, in vitro and in vivo. In brainstem slices from Phox2b-eGFP mice, the firing of pH-sensitive RTN neurons was strongly increased by isoflurane, independent of prevailing pH conditions. At least two ionic mechanisms contributed to anesthetic activation of RTN neurons: activation of a Na+-dependent cationic current and inhibition of a background K+ current. Single cell RT-PCR analysis of dissociated GFP-labeled RTN neurons revealed expression of THIK-1 (K2P13.1), a channel that shares key properties with the native RTN current (i.e., suppression by inhalational anesthetics, weak rectification, inhibition by extracellular Na+, and pH-insensitivity). Isoflurane also increased firing rate of RTN chemosensitive neurons in urethane-anesthetized rats, again independent of CO2 levels. In these animals, isoflurane transiently enhanced activity of the respiratory system, an effect that was most prominent at low levels of respiratory drive and mediated largely by an increase in respiratory frequency. These data indicate that inhalational anesthetics cause activation of RTN neurons, which serve an important integrative role in respiratory control; the increased drive provided by enhanced RTN neuronal activity may contribute, in part, to maintaining respiratory motor activity under immobilizing anesthetic conditions. PMID:20610767

  6. A highly calcium-selective cation current activated by intracellular calcium release in MDCK cells.

    PubMed

    Delles, C; Haller, T; Dietl, P

    1995-08-01

    1. The whole-cell patch clamp technique and fluorescence microscopy with the Ca2+ indicators fura-2 and fluo-3 were used to measure the whole-cell current and the free intracellular Ca2+ concentration ([Ca2+]i) in Madin-Darby canine kidney (MDCK) cells. 2. In a Ca(2+)-free bath solution, thapsigargin (TG) caused a transient increase of [Ca2+]i. Subsequent addition of Ca2+ caused a long lasting elevation of [Ca2+]i. 3. In a Ca(2+)-free bath solution, extracellular application of TG, ATP or ionomycin, or intracellular application of inositol 1,4,5-trisphosphate (IP3), caused a small but significant inward current (Iin) and a transient outward Ca(2+)-dependent K+ current (IK(Ca)), consistent with intracellular Ca2+ release. Subsequent addition of Ca2+ induced a prominent Iin with a current density of -4.2 +/- 0.7 pA pF-1. This Iin was unaffected by inositol 1,3,4,5-tetrakisphosphate (IP4). 4. Na+ replacement by mannitol, N-methyl-D-glucamine+ (NMG+), aminomethylidin-trimethanol+ (Tris+) or choline+ reduced Iin by 54, 65, 52 and 56%, respectively. This indicates an apparent Ca2+ selectivity over Na+ of 26:1. Iin was, however, unaffected by replacing Cl- with gluconate- or by the K+ channel blocker charybdotoxin (CTX). 5. Iin was completely blocked by La3+ (IC50 = 0.77 microM). Consistently, La3+ completely reversed the TG-induced elevation of [Ca2+]i. SK&F 96365 (1-[3-(4-methoxyphenyl)-propoxyl]-1-(4-methoxy-phenyl)-ethyl-1H-im idazole) HCl did not inhibit the TG-induced Iin. It did, however, exhibit a biphasic effect on [Ca2+]i, consisting of an initial Ca2+ decay and a subsequent Ca2+ elevation. La3+ completely reversed the SK&F 96365-induced elevation of [Ca2+]i. 6. In the absence of Na+, Iin was dependent on the bath Ca2+ concentration (EC50 = 1.02 mM). Ca2+ replacement by Ba2+ or Mn2+ resulted in a reduction of Iin by 95 and 94%, respectively. 7. From these experiments we conclude that Ca2+ release from intracellular Ca2+ stores, induced by different independent

  7. The morphology of flare phenomena, magnetic fields, and electric currents in active regions. I - Introduction and methods

    NASA Technical Reports Server (NTRS)

    Canfield, Richard C.; De La Beaujardiere, J.-F.; Fan, Yuhong; Leka, K. D.; Mcclymont, A. N.; Metcalf, Thomas R.; Mickey, Donald L.; Wuelser, Jean-Pierre; Lites, Bruce W.

    1993-01-01

    Electric current systems in solar active regions and their spatial relationship to sites of electron precipitation and high-pressure in flares were studied with the purpose of providing observational evidence for or against the flare models commonly discussed in the literature. The paper describes the instrumentation, the data used, and the data analysis methods, as well as improvements made upon earlier studies. Several flare models are overviewed, and the predictions yielded by each model for the relationships of flares to the vertical current systems are discussed.

  8. Cytosolic Ca2+ and Ca2+-activated Cl− current dynamics: insights from two functionally distinct mouse exocrine cells

    PubMed Central

    Giovannucci, David R; Bruce, Jason I. E; Straub, Stephen V; Arreola, Jorge; Sneyd, James; Shuttleworth, Trevor J; Yule, David I

    2002-01-01

    The dynamics of Ca2+ release and Ca2+-activated Cl− currents in two related, but functionally distinct exocrine cells, were studied to gain insight into how the molecular specialization of Ca2+ signalling machinery are utilized to produce different physiological endpoints: in this case, fluid or exocytotic secretion. Digital imaging and patch-clamp methods were used to monitor the temporal and spatial properties of changes in cytosolic Ca2+ concentration ([Ca2+]c) and Cl− currents following the controlled photolytic release of caged-InsP3 or caged-Ca2+. In parotid and pancreatic acinar cells, changes in [Ca2+]c and activation of a Ca2+-activated Cl− current occurred with close temporal coincidence. In parotid, a rapid global Ca2+ signal was invariably induced, even with low-level photolytic release of threshold amounts of InsP3. In pancreas, threshold stimulation generated an apically delimited [Ca2+]c signal, while a stronger stimulus induced a global [Ca2+]c signal which exhibited characteristics of a propagating wave. InsP3 was more effective in parotid, where [Ca2+]c signals initiated with shorter latency and exhibited a faster time-to-peak than in pancreas. The increased potency of InsP3 in parotid probably results from a four-fold higher number of InsP3 receptors as measured by radiolabelled InsP3 binding and western blot analysis. The Ca2+ sensitivity of the Cl− channels in parotid and pancreas was determined from the [Ca2+]-current relationship measured during a dynamic ‘Ca2+ ramp’ produced by the continuous, low-level photolysis of caged-Ca2+. In addition to a greater number of InsP3 receptors, the Cl− current density of parotid acinar cells was more than four-fold greater than that of pancreatic cells. Whereas activation of the current was tightly coupled to increases in Ca2+ in both cell types, local Ca2+ clearance was found to contribute substantially to the deactivation of the current in parotid. These data reveal specializations of

  9. Active shielding to reduce low frequency disturbances in direct current near biomagnetic measurements

    NASA Astrophysics Data System (ADS)

    Platzek, D.; Nowak, H.; Giessler, F.; Röther, J.; Eiselt, M.

    1999-05-01

    Measurements of dc near biomagnetic fields are disturbed by low frequency noise that is not reduced sufficiently by most of the magnetically shielded rooms or gradiometers. For this reason an active shielding system has been developed at the Biomagnetic Center of the University of Jena. This work describes the principle of the active shielding system and demonstrates its properties concerning the attenuation of disturbing fields, frequency range, and some applications in biomedical measurements. We achieved a reduction of external low frequency magnetic fields by more than 50 dB and an attenuation of the field gradient by about 25 dB. This active shielding enables measurements of near dc biomagnetic fields in investigations of periinfarct depolarizations after ischemic stroke and spreading depression in migraine patients.

  10. Active Currents and Stresses on the cell surface: Clustering, Instabilities and Budding

    NASA Astrophysics Data System (ADS)

    Rao, Madan

    2011-03-01

    We study the contractile dynamics of a collection of active polar filaments, such as actin, on a two dimensional substrate, using a continuum hydrodynamic description in the presence of spatiotemporal noise. The steady states, characterized by a variety of phases generically consisting of a transient collection of inward pointing asters. We next study the dynamics of particles advected along these active filaments. This is relevant to the dynamics and organization of a large class of cell surface molecules. We make several predictions regarding the statistics of fluctuations of these passive advective particles which we confirm using fluorescence based experiments. We then show how such active patterning of filaments can give rise to membrane stresses leading to membrane shape deformations. In collaboration with Kripa Gowrishankar and Satyajit Mayor.

  11. Current evidence for the hepatoprotective activities of the medicinal mushroom Antrodia cinnamomea

    PubMed Central

    2013-01-01

    Antrodia cinnamomea (AC) is an endemic mushroom species of Taiwan, and has been demonstrated to possess diverse biological and pharmacological activities, such as anti-hypertension, anti-hyperlipidemia, anti-inflammation, anti-oxidation, anti-tumor, and immunomodulation. This review focuses on the inhibitory effects of AC on hepatitis, hepatocarcinoma, and alcohol-induced liver diseases (e.g., fatty liver, fibrosis). The relevant biochemical and molecular mechanisms are addressed. Overall, this review summarizes the hepatoprotective activities in vitro and in vivo. However, there is no doubt that human and clinical trials are still limited, and further studies are required for the development of AC-related products. PMID:24180549

  12. Tea and human health: biomedical functions of tea active components and current issues.

    PubMed

    Chen, Zong-mao; Lin, Zhi

    2015-02-01

    Originating in China, tea and tea planting have spread throughout the world since the middle of the Tang dynasty. Now people from 160 countries in the world are accustomed to tea drinking. A brief history of tea's medicinal role in China and its spread to the world are introduced. The effectiveness of tea active components and tea drinking on major human diseases, including cancer, metabolic syndrome, cardiovascular disease, and neurodegenerative diseases, is discussed. Also presented are some related issues, such as the bioavailability of tea active components, the new formulations of tea polyphenols, and the safety for consumers of dietary supplements containing tea polyphenols. PMID:25644464

  13. Tea and human health: biomedical functions of tea active components and current issues*

    PubMed Central

    Chen, Zong-mao; Lin, Zhi

    2015-01-01

    Originating in China, tea and tea planting have spread throughout the world since the middle of the Tang dynasty. Now people from 160 countries in the world are accustomed to tea drinking. A brief history of tea’s medicinal role in China and its spread to the world are introduced. The effectiveness of tea active components and tea drinking on major human diseases, including cancer, metabolic syndrome, cardiovascular disease, and neurodegenerative diseases, is discussed. Also presented are some related issues, such as the bioavailability of tea active components, the new formulations of tea polyphenols, and the safety for consumers of dietary supplements containing tea polyphenols. PMID:25644464

  14. International Global Atmospheric Chemistry Programme global emissions inventory activity: Sulfur emissions from volcanoes, current status

    SciTech Connect

    Benkovitz, C.M.

    1995-07-01

    Sulfur emissions from volcanoes are located in areas of volcanic activity, are extremely variable in time, and can be released anywhere from ground level to the stratosphere. Previous estimates of global sulfur emissions from all sources by various authors have included estimates for emissions from volcanic activity. In general, these global estimates of sulfur emissions from volcanoes are given as global totals for an ``average`` year. A project has been initiated at Brookhaven National Laboratory to compile inventories of sulfur emissions from volcanoes. In order to complement the GEIA inventories of anthropogenic sulfur emissions, which represent conditions circa specific years, sulfur emissions from volcanoes are being estimated for the years 1985 and 1990.

  15. Ginsenoside Rg3 Enhances Large Conductance Ca2+-Activated Potassium Channel Currents: A Role of Tyr360 Residue

    PubMed Central

    Choi, Sun-Hye; Shin, Tae-Joon; Lee, Byung-Hwan; Hwang, Sung Hee; Lee, Sang-Mok; Lee, Byung-Cheol; Park, Cheol-Seung; Ha, Tal Soo; Nah, Seung-Yeol

    2011-01-01

    Ginsenosides, active ingredients of Panax ginseng, are known to exhibit neuroprotective effects. Large-conductance Ca2+-activated K+ (BKCa) channels are key modulators of cellular excitability of neurons and vascular smooth muscle cells. In the present study, we examined the effects of ginsenosides on rat brain BKCa (rSlo) channel activity heterologously expressed in Xenopus oocytes to elucidate the molecular mechanisms how ginsenoside regulates the BKCa channel activity. Ginsenoside Rg3 (Rg3) enhanced outward BKCa channel currents. The Rg3-enhancement of outward BKCa channel currents was concentration-dependent, voltage-dependent, and reversible. The EC50 was 15.1 ± 3.1 μM. Rg3 actions were not desensitized by repeated treatment. Tetraetylammonium (TEA), a K+ channel blocker, inhibited BKCa channel currents. We examined whether extracellular TEA treatment could alter the Rg3 action and vice versa. TEA caused a rightward shift of the Rg3 concentration-response curve (i.e., much higher concentration of Rg3 is required for the activation of BKCa channel compared to the absence of TEA), while Rg3 caused a rightward shift of the TEA concentration-response curve in wild-type channels. Mutation of the extracellular TEA binding site Y360 to Y360I caused a rightward shift of the TEA concentration-response curve and almost abolished both the Rg3 action and Rg3-induced rightward shift of TEA concentration-response curve. These results indicate that Tyr360 residue of BKCa channel plays an important role in the Rg3-enhancement of BKCa channel currents. PMID:21191818

  16. 77 FR 55858 - Agency Information Collection Activities: E-Verify Program; Revision of a Currently Approved...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-11

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  17. 77 FR 31033 - Agency Information Collection Activities: Form I-589, Extension of a Currently Approved...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-24

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    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-21

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  19. 77 FR 34398 - Agency Information Collection Activities: Form N-565, Extension of a Currently Approved...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-11

    ..., 2012, at 77 FR 18255, allowing for a 60-day public comment period. USCIS did not receive any comments... SECURITY U.S. Citizenship and Immigration Services Agency Information Collection Activities: Form N-565... Immigration Services (USCIS) will be submitting the following information collection request to the Office...

  20. 77 FR 3485 - Agency Information Collection Activities: Form I-129F, Extension of a Currently Approved...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-24

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