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Sample records for active input current

  1. Influence of active dendritic currents on input-output processing in spinal motoneurons in vivo.

    PubMed

    Lee, R H; Kuo, J J; Jiang, M C; Heckman, C J

    2003-01-01

    The extensive dendritic tree of the adult spinal motoneuron generates a powerful persistent inward current (PIC). We investigated how this dendritic PIC influenced conversion of synaptic input to rhythmic firing. A linearly increasing, predominantly excitatory synaptic input was generated in triceps ankle extensor motoneurons by slow stretch (duration: 2-10 s) of the Achilles tendon in the decerebrate cat preparation. The firing pattern evoked by stretch was measured by injecting a steady current to depolarize the cell to threshold for firing. The effective synaptic current (I(N), the net synaptic current reaching the soma of the cell) evoked by stretch was measured during voltage clamp. Hyperpolarized holding potentials were used to minimize the activation of the dendritic PIC and thus estimate stretch-evoked I(N) for a passive dendritic tree (I(N,PASS)). Depolarized holding potentials that approximated the average membrane potential during rhythmic firing allowed strong activation of the dendritic PIC and thus resulted in marked enhancement of the total stretch-evoked I(N) (I(N,TOT)). The net effect of the dendritic PIC on the generation of rhythmic firing was assessed by plotting stretch-evoked firing (strong PIC activation) versus stretch-evoked I(N,PASS) (minimal PIC activation). The gain of this input-output function for the neuron (I-O(N)) was found to be ~2.7 times as high as for the standard injected frequency current (F-I) function in low-input conductance neurons. However, about halfway through the stretch, firing rate tended to become constant, resulting in a sharp saturation in I-O(N) that was not present in F-I. In addition, the gain of I-O(N) decreased sharply with increasing input conductance, resulting in much lower stretch-evoked firing rates in high-input conductance cells. All three of these phenomena (high initial gain, saturation, and differences in low- and high-input conductance cells) were also readily apparent in the differences between

  2. 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.

  3. 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.

  4. 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.

  5. 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…

  6. Active inrush-current limiter

    NASA Technical Reports Server (NTRS)

    Kichak, R. A.

    1977-01-01

    By stretching turn-on time from approximately 1 to 200 ms, effects of inrush current (and of associated large current spikes) and current rate of rise (dl/dt) are made potentially less severe. Limiter arrangement consists of time-variable impedance connected in series between input dc power source return and power circuit of converter.

  7. Integrated ZVS DC-DC converter with continuous input current and high voltage gain

    NASA Astrophysics Data System (ADS)

    Do, Hyun-Lark

    2011-09-01

    An integrated zero-voltage-switching (ZVS) DC-DC converter with continuous input current and high voltage gain is proposed. The proposed converter can operate with soft switching, a continuous inductor current and fixed switching frequency. The voltage stress of the power switches is relatively low compared to the output voltage. Moreover, soft-switching characteristic of the proposed converter reduces switching loss of active power switches and raise the conversion efficiency. The reverse-recovery problem of output rectifiers is also alleviated by controlling the current changing rates of diodes with the use of the leakage inductance of a coupled inductor. The operation and performance of the proposed DC-DC converter were verified on an 115 W experimental prototype operating at 100 kHz.

  8. 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.

  9. Improvement of Input Current Waveform for Soft-Switching Boost DCM Converter with Unity Power Factor

    NASA Astrophysics Data System (ADS)

    Taniguchi, Katsunori; Morizane, Toshimitsu; Kimura, Noriyuki

    In this paper, a soft-switching discontinuous mode (DCM) power factor corrected (PFC) converter is analyzed by applying the double Fourier series expansion. It is found that the fundamental component and higher-order harmonics included in the input current waveform are obtained by the Fourier series expansion of the mean value of the inductor current. From the theoretical analysis, a new method removing the distortion of the input current waveform is proposed. In spite of an open loop system, the proposed method makes a great improvement of the total harmonic distortion even if the ratio of output voltage to input voltage is very low.

  10. 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

  11. 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.

  12. Modulation of the input-output function by GABAA receptor-mediated currents in rat oculomotor nucleus motoneurons.

    PubMed

    Torres-Torrelo, Julio; Torres, Blas; Carrascal, Livia

    2014-11-15

    The neuronal input-output function depends on recruitment threshold and gain of the firing frequency-current (f-I) relationship. These two parameters are positively correlated in ocular motoneurons (MNs) recorded in alert preparation and inhibitory inputs could contribute to this correlation. Phasic inhibition mediated by γ-amino butyric acid (GABA) occurs when a high concentration of GABA at the synaptic cleft activates postsynaptic GABAA receptors, allowing neuronal information transfer. In some neuronal populations, low concentrations of GABA activate non-synaptic GABAA receptors and generate a tonic inhibition, which modulates cell excitability. This study determined how ambient GABA concentrations modulate the input-output relationship of rat oculomotor nucleus MNs. Superfusion of brain slices with GABA (100 μm) produced a GABAA receptor-mediated current that reduced the input resistance, increased the recruitment threshold and shifted the f-I relationship rightward without any change in gain. These modifications did not depend on MN size. In absence of exogenous GABA, gabazine (20 μm; antagonist of GABAA receptors) abolished spontaneous inhibitory postsynaptic currents and revealed a tonic current in MNs. Gabazine increased input resistance and decreased recruitment threshold mainly in larger MNs. The f-I relationship shifted to the left, without any change in gain. Gabazine effects were chiefly due to MN tonic inhibition because tonic current amplitude was five-fold greater than phasic. This study demonstrates a tonic inhibition in ocular MNs that modulates cell excitability depending on cell size. We suggest that GABAA tonic inhibition acting concurrently with glutamate receptors activation could reproduce the positive covariation between threshold and gain reported in alert preparation.

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. Phase response curves of subthalamic neurons measured with synaptic input and current injection

    PubMed Central

    Wilson, Charles J.

    2012-01-01

    Infinitesimal phase response curves (iPRCs) provide a simple description of the response of repetitively firing neurons and may be used to predict responses to any pattern of synaptic input. Their simplicity makes them useful for understanding the dynamics of neurons when certain conditions are met. For example, the sizes of evoked phase shifts should scale linearly with stimulus strength, and the form of the iPRC should remain relatively constant as firing rate varies. We measured the PRCs of rat subthalamic neurons in brain slices using corticosubthalamic excitatory postsynaptic potentials (EPSPs; mediated by both AMPA- and NMDA-type receptors) and injected current pulses and used them to calculate the iPRC. These were relatively insensitive to both the size of the stimulus and the cell's firing rate, suggesting that the iPRC can predict the response of subthalamic nucleus cells to extrinsic inputs. However, the iPRC calculated using EPSPs differed from that obtained using current pulses. EPSPs (normalized for charge) were much more effective at altering the phase of subthalamic neurons than current pulses. The difference was not attributable to the extended time course of NMDA receptor-mediated currents, being unaffected by blockade of NMDA receptors. The iPRC provides a good description of subthalamic neurons' response to input, but iPRCs are best estimated using synaptic inputs rather than somatic current injection. PMID:22786957

  18. 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…

  19. Active control of multi-input hydraulic journal bearing system

    NASA Astrophysics Data System (ADS)

    Chuang, Jen-Chen; Chen, Chi-Yin; Tu, Jia-Ying

    2016-09-01

    Because of the advantages of high accuracy, high capacity, and low friction, the development of hydrostatic bearing for machine tool receives significant attention in the last decades. The mechanics and mechanical design of hydrostatic journal bearing with capillary restrictors has been discussed in literature. However, pragmatically, the undesired loading effects of cutting force tend to result in resonance and instability of the rotor and damage the shaft during operation. Therefore, multi-input, active flow control using state feedback design is proposed in this paper. To this purpose, the proportional pressure valves are added to the hydraulic system as active control devices, and the linearised models of the bearing and valve are discussed and identified. Simulation and experimental work is conducted to verify the proposed active control and parameter identification techniques. The results show that the unbalance responses of the rotor are reduced by the proposed state feedback controller, which is able to regulate the flow pressure effectively, thus enhancing the stability and accuracy of the hydraulic journal bearing.

  20. 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

  1. A single/two-phase, regenerative, variable speed, induction motor drive with sinusoidal input current

    SciTech Connect

    Rahman, M.F.; Zhong, L.

    1995-12-31

    The single phase induction motor with two windings, main and auxiliary, is probably the most widely used motor in the world. The mains operated single-phase motor usually operates at low power factor, low efficiency and at fixed speed. At most, two or three fixed speeds are provided when required, through manual intervention. Such fixed speed operation hinders product designers from incorporating many interesting and useful features in their products. The present concern on harmonic pollution of the supply and low power factor operation, as embodied in the recent IEC555-2 standard, also calls for power factor correction measures to be included in applications where a single phase motor is used. This paper presents a variable speed single-phase motor (with two windings) drive that utilizes just six switches as found in the emerging intelligent power modules (IPM). Just one integrated module with six switches serves to implement the input rectifier with sinusoidal input current, and the two-phase VSI or CSI inverter to drive the two phases of the motor with balanced ampere-turns. The input rectifier is also reversible, so that the motor can be braked with energy return to the mains, thus operating with high efficiency at all times.

  2. 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.

  3. Current source density correlates of cerebellar Golgi and Purkinje cell responses to tactile input

    PubMed Central

    Tahon, Koen; Wijnants, Mike; De Schutter, Erik

    2011-01-01

    The overall circuitry of the cerebellar cortex has been known for over a century, but the function of many synaptic connections remains poorly characterized in vivo. We used a one-dimensional multielectrode probe to estimate the current source density (CSD) of Crus IIa in response to perioral tactile stimuli in anesthetized rats and to correlate current sinks and sources to changes in the spike rate of corecorded Golgi and Purkinje cells. The punctate stimuli evoked two distinct early waves of excitation (at <10 and ∼20 ms) associated with current sinks in the granular layer. The second wave was putatively of corticopontine origin, and its associated sink was located higher in the granular layer than the first trigeminal sink. The distinctive patterns of granular-layer sinks correlated with the spike responses of corecorded Golgi cells. In general, Golgi cell spike responses could be linearly reconstructed from the CSD profile. A dip in simple-spike activity of coregistered Purkinje cells correlated with a current source deep in the molecular layer, probably generated by basket cell synapses, interspersed between sparse early sinks presumably generated by synapses from granule cells. The late (>30 ms) enhancement of simple-spike activity in Purkinje cells was characterized by the absence of simultaneous sinks in the granular layer and by the suppression of corecorded Golgi cell activity, pointing at inhibition of Golgi cells by Purkinje axon collaterals as a likely mechanism of late Purkinje cell excitation. PMID:21228303

  4. Sensory-evoked perturbations of locomotor activity by sparse sensory input: a computational study.

    PubMed

    Bui, Tuan V; Brownstone, Robert M

    2015-04-01

    Sensory inputs from muscle, cutaneous, and joint afferents project to the spinal cord, where they are able to affect ongoing locomotor activity. Activation of sensory input can initiate or prolong bouts of locomotor activity depending on the identity of the sensory afferent activated and the timing of the activation within the locomotor cycle. However, the mechanisms by which afferent activity modifies locomotor rhythm and the distribution of sensory afferents to the spinal locomotor networks have not been determined. Considering the many sources of sensory inputs to the spinal cord, determining this distribution would provide insights into how sensory inputs are integrated to adjust ongoing locomotor activity. We asked whether a sparsely distributed set of sensory inputs could modify ongoing locomotor activity. To address this question, several computational models of locomotor central pattern generators (CPGs) that were mechanistically diverse and generated locomotor-like rhythmic activity were developed. We show that sensory inputs restricted to a small subset of the network neurons can perturb locomotor activity in the same manner as seen experimentally. Furthermore, we show that an architecture with sparse sensory input improves the capacity to gate sensory information by selectively modulating sensory channels. These data demonstrate that sensory input to rhythm-generating networks need not be extensively distributed. PMID:25673740

  5. 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

  6. 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.

  7. Orexin-dependent activation of layer VIb enhances cortical network activity and integration of non-specific thalamocortical inputs.

    PubMed

    Hay, Y Audrey; Andjelic, Sofija; Badr, Sammy; Lambolez, Bertrand

    2015-11-01

    Neocortical layer VI is critically involved in thalamocortical activity changes during the sleep/wake cycle. It receives dense projections from thalamic nuclei sensitive to the wake-promoting neuropeptides orexins, and its deepest part, layer VIb, is the only cortical lamina reactive to orexins. This convergence of wake-promoting inputs prompted us to investigate how layer VIb can modulate cortical arousal, using patch-clamp recordings and optogenetics in rat brain slices. We found that the majority of layer VIb neurons were excited by nicotinic agonists and orexin through the activation of nicotinic receptors containing α4-α5-β2 subunits and OX2 receptor, respectively. Specific effects of orexin on layer VIb neurons were potentiated by low nicotine concentrations and we used this paradigm to explore their intracortical projections. Co-application of nicotine and orexin increased the frequency of excitatory post-synaptic currents in the ipsilateral cortex, with maximal effect in infragranular layers and minimal effect in layer IV, as well as in the contralateral cortex. The ability of layer VIb to relay thalamocortical inputs was tested using photostimulation of channelrhodopsin-expressing fibers from the orexin-sensitive rhomboid nucleus in the parietal cortex. Photostimulation induced robust excitatory currents in layer VIa neurons that were not pre-synaptically modulated by orexin, but exhibited a delayed, orexin-dependent, component. Activation of layer VIb by orexin enhanced the reliability and spike-timing precision of layer VIa responses to rhomboid inputs. These results indicate that layer VIb acts as an orexin-gated excitatory feedforward loop that potentiates thalamocortical arousal.

  8. 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....

  9. 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....

  10. 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.

  11. 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.

  12. A current type PWM rectifier with active damping function

    SciTech Connect

    Sato, Yukihiko; Kataoka, Teruo

    1995-12-31

    A new control method for current type 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 feed-back 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 is 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.

  13. 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.

  14. 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…

  15. 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.

  16. Schaffer collateral and perforant path inputs activate different subtypes of NMDA receptors on the same CA1 pyramidal cell

    PubMed Central

    Arrigoni, Elda; Greene, Robert W

    2004-01-01

    The two major inputs to CA1 pyramidal neurons, the perforant pathway (PP) that terminates on distal dendrites and the Schaffer collaterals (SCH) that terminate on proximal dendrites, activate both AMPA and N-methyl-D-aspartate (NMDA) receptors. In an in vitro slice preparation, the pharmacologically isolated NMDA receptor-mediated excitatory postsynaptic currents (EPSCs) (NMDA-EPSCs) of either pathway can be selectively activated onto a single CA1 pyramidal neuron. Analysis of the decay phase of PP and SCH NMDA-EPSCs revealed no significant difference in their time constants, suggesting no apparent different distribution in NR2-subunit composition in the NMDA receptors (NMDAR) activated by the two synaptic inputs. However, application of the NR2B-selective antagonist, ifenprodil, differently affected the NMDA-EPSCs activated by the PP and SCH inputs. The reduction of the PP responses was only 30% compared to 75% for the SCH responses. In addition, for both pathways, the ifenprodil-insensitive component of the NMDA-EPSCs had significantly more rapid decay kinetics than those prior to application of ifenprodil. Our results show a greater NR2B subunit contribution to the NMDA component of the SCH EPSC, compared to the NMDA component of the PP EPSC and that in single CA1 pyramidal neurons NMDA composition is anatomically specific to the afferent input. PMID:15155538

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

    NASA Astrophysics Data System (ADS)

    Wolf, R. A.; Kamide, Y.

    1983-10-01

    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.

  18. 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.

  19. Nicotine enhances both excitatory and inhibitory synaptic inputs to inspiratory-activated airway vagal preganglionic neurons.

    PubMed

    Zhou, Xujiao; Chen, Yonghua; Ge, Dengyun; Yuan, Wenjun; Wang, Jijiang

    2013-01-01

    The airway vagal preganglionic neurons (AVPNs) supply the essential excitatory drive to the postganglionic neurons and dominate the neural control of the airway both physiologically and pathophysiologically. The AVPNs express multiple subunits of nicotinic acetylcholine receptors (nAChRs), but the influences of exogenous nicotine and endogenous acetylcholine are unknown. This study examined the effects of nicotine and endogenous acetylcholine on retrogradely labelled, functionally identified inspiratory-activated AVPNs (IA-AVPNs) using the patch-clamp technique. Nicotine (10 μmol l(-1)) significantly increased the frequency and amplitude of the spontaneous EPSCs of IA-AVPNs, and these effects were insensitive to methyllycaconitine (MLA, 100 nmol l(-1)), an antagonist of the α7 type of nAChR, but was prevented by dihydro-β-erythroidine (DHβE, 3 μmol l(-1)), an antagonist of the α4β2 type of nAChR. Nicotine caused a tonic inward current in IA-AVPNs, which was reduced by MLA or DHβE alone, but was not abolished by co-application of MLA and DHβE. Nicotine caused a significant increase in the frequency of GABAergic and glycinergic spontaneous IPSCs and significantly increased the amplitude of glycinergic spontaneous IPSCs, all of which were prevented by DHβE. Nicotine had no effects on the miniature EPSCs or miniature IPSCs following pretreatment with TTX. Under current clamp, nicotine caused depolarization and increased the firing rate of IA-AVPNs during inspiratory intervals. Neostigmine (10 μmol l(-1)), an acetylcholinesterase inhibitor, mimicked the effects of nicotine. These results demonstrate that nicotine and endogenous ACh enhance the excitatory and inhibitory synaptic inputs of IA-AVPNs and cause a postsynaptic excitatory current and that the nicotinic effects are mediated presynaptically by activation of the α4β2 type of nAChR and postsynaptically by activation of multiple nAChRs, including α7 and α4β2 types.

  20. Unity power factor converter based on a fuzzy controller and predictive input current.

    PubMed

    Bouafassa, Amar; Rahmani, Lazhar; Kessal, Abdelhalim; Babes, Badreddine

    2014-11-01

    This paper proposes analysis and control of a single-phase power factor corrector (PFC). The proposed control is capable of achieving a unity power factor for each DC link voltage or load fluctuation. The method under study is composed of two intelligent approaches, a fuzzy logic controller to ensure an output voltage at a suitable value and predictive current control. The fuzzy controller is used with minimum rules to attain a low cost. The method is verified and discussed through simulation on the MATLAB/Simulink platform. It presents high dynamic performance under various parameter changes. Moreover, in order to examine and evaluate the method in real-time, a test bench is built using dSPACE 1104. The implantation of the proposed method is very easy and flexible and allows for operation under parameter variations. Additionally, the obtained results are very significant.

  1. 77 FR 55486 - Agency Information Collection Activities: Importer ID Input Record

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-10

    ... collection techniques or the use of other forms of information technology; and (e) the annual costs burden to... SECURITY U.S. Customs and Border Protection Agency Information Collection Activities: Importer ID Input... and request for comments; Extension of an existing collection of information. SUMMARY: U.S....

  2. Endogenous acetylcholine and nicotine activation enhances GABAergic and glycinergic inputs to cardiac vagal neurons.

    PubMed

    Wang, Jijiang; Wang, Xin; Irnaten, Mustapha; Venkatesan, Priya; Evans, Cory; Baxi, Sunit; Mendelowitz, David

    2003-05-01

    The heart slows during expiration and heart rate increases during inspiration. This cardiorespiratory interaction is thought to occur by increased inhibitory synaptic events to cardiac vagal neurons during inspiration. Since cholinergic receptors have been suggested to be involved in this cardiorespiratory interaction, we tested whether endogenous cholinergic activity modulates GABAergic and glycinergic neurotransmission to cardiac vagal neurons in the nucleus ambiguus, whether nicotine can mimic this facilitation, and we examined the nicotinic receptors involved. Cardiac vagal neurons in the rat were labeled with a retrograde fluorescent tracer and studied in an in vitro slice using patch-clamp techniques. Application of neostigmine (10 microM), an acetylcholinerase inhibitor, significantly increased the frequency of both GABAergic and glycinergic inhibitory postsynaptic currents (IPSCs) in cardiac vagal neurons. Exogenous application of nicotine increased the frequency and amplitude of both GABAergic and glycinergic IPSCs. The nicotinic facilitation of both GABAergic and glycinergic IPSCs were insensitive to 100 nM alpha-bungarotoxin but were abolished by dihydro-beta-erythrodine (DHbetaE) at a concentration (3 microM) specific for alpha4beta2 nicotinic receptors. In the presence of TTX, nicotine increased the frequency of GABAergic and glycinergic miniature synaptic events, which were also abolished by DHbetaE (3 microM). This work demonstrates that there is endogenous cholinergic facilitation of GABAergic and glycinergic synaptic inputs to cardiac vagal neurons, and activation of alpha4beta2 nicotinic receptors at presynaptic terminals facilitates GABAergic and glycinergic neurotransmission to cardiac vagal neurons. Nicotinic facilitation of inhibitory neurotransmission to premotor cardiac parasympathetic neurons may be involved in generating respiratory sinus arrhythmia.

  3. 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.

  4. Correlated activity of cortical neurons survives extensive removal of feedforward sensory input

    PubMed Central

    Shapcott, Katharine A.; Schmiedt, Joscha T.; Saunders, Richard C.; Maier, Alexander; Leopold, David A.; Schmid, Michael C.

    2016-01-01

    A fundamental property of brain function is that the spiking activity of cortical neurons is variable and that some of this variability is correlated between neurons. Correlated activity not due to the stimulus arises from shared input but the neuronal circuit mechanisms that result in these noise correlations are not fully understood. Here we tested in the visual system if correlated variability in mid-level area V4 of visual cortex is altered following extensive lesions of primary visual cortex (V1). To this end we recorded longitudinally the neuronal correlations in area V4 of two behaving macaque monkeys before and after a V1 lesion while the monkeys fixated a grey screen. We found that the correlations of neuronal activity survived the lesions in both monkeys. In one monkey, the correlation of multi-unit spiking signals was strongly increased in the first week post-lesion, while in the second monkey, correlated activity was slightly increased, but not greater than some week-by-week fluctuations observed. The typical drop-off of inter-neuronal correlations with cortical distance was preserved after the lesion. Therefore, as V4 noise correlations remain without feedforward input from V1, these results suggest instead that local and/or feedback input seem to be necessary for correlated activity. PMID:27721468

  5. Diversity of LFPs Activated in Different Target Regions by a Common CA3 Input.

    PubMed

    Martín-Vázquez, Gonzalo; Benito, Nuria; Makarov, Valeri A; Herreras, Oscar; Makarova, Julia

    2016-10-01

    Identifying the pathways contributing to local field potential (LFP) events and oscillations is essential to determine whether synchronous interregional patterns indicate functional connectivity. Here, we studied experimentally and numerically how different target structures receiving input from a common population shape their LFPs. We focused on the bilateral CA3 that sends gamma-paced excitatory packages to the bilateral CA1, the lateral septum, and itself (recurrent input). The CA3-specific contribution was isolated from multisite LFPs in target regions using spatial discrimination techniques. We found strong modulation of LFPs by target-specific features, including the morphology and population arrangement of cells, the timing of CA3 inputs, volume conduction from nearby targets, and co-activated inhibition. Jointly they greatly affect the LFP amplitude, profile, and frequency characteristics. For instance, ipsilateral (Schaffer) LFPs occluded contralateral ones, and septal LFPs arise mostly from remote sources while local contribution from CA3 input was minor. In the CA3 itself, gamma waves have dual origin from local networks: in-phase excitatory and nearly antiphase inhibitory. Also, waves may have different duration and varying phase in different targets. These results indicate that to explore the cellular basis of LFPs and the functional connectivity between structures, besides identifying the origin population/s, target modifiers should be considered.

  6. Neural encoding of input transients investigated by intracellular injection of ramp currents in cat α-motoneurones

    PubMed Central

    Baldissera, F.; Campadelli, Paola; Piccinelli, L.

    1982-01-01

    1. Input—output relations were analysed in spinal α-motoneurones during current transients reaching a steady level after a linear growth of different slopes. The motoneurone output considered in the analysis was the instantaneous frequency of the cell discharge. 2. In all motoneurones firing frequency during the ramp exceeded that of the final steady level and it was related to the velocity of rise of the current. In the majority of motoneurones the instantaneous frequency grew during the ramp stimulus, as if it were dependent on current intensity as well as on its rate of rise. Only in a few cells was firing frequency constant over the first two interspike intervals during the ramp, as would be expected if this response depended solely on the rate of rise. 3. Frequency—velocity (f/v) plots for different rates of rise of the injected current showed a linear relation for each interspike interval. Presence or absence of an intensity component was revealed in these plots by divergence or, respectively, overlapping of the f/v relations for the first and second intervals. Divergence was eliminated by subtraction of the estimated intensity component. The slope of the f/v relation for the first interval did not change significantly after subtraction of the intensity component and was taken as an index of the dynamic sensitivity of the motoneurones. The slope of the f/v relation varied greatly (from 47 to 330 impulses s-1. (nA ms-1)-1) in the population examined and was higher in motoneurones with a long-lasting afterhyperpolarization (a.h.p.) than in those where it was short-lasting. 4. It is proposed that the ability of the motoneurones to encode both the steady level and the rate of change of input signals depends on the conductance changes responsible for the a.h.p. and their accumulation. A positive correlation was found between the size of the a.h.p. potassium current, estimated as a.h.p. peak voltage/cell input resistance, and the slope of the f/v relation for

  7. 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.

  8. 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.

  9. A transcriptional mechanism integrating inputs from extracellular signals to activate hippocampal stem cells.

    PubMed

    Andersen, Jimena; Urbán, Noelia; Achimastou, Angeliki; Ito, Ayako; Simic, Milesa; Ullom, Kristy; Martynoga, Ben; Lebel, Mélanie; Göritz, Christian; Frisén, Jonas; Nakafuku, Masato; Guillemot, François

    2014-09-01

    The activity of adult stem cells is regulated by signals emanating from the surrounding tissue. Many niche signals have been identified, but it is unclear how they influence the choice of stem cells to remain quiescent or divide. Here we show that when stem cells of the adult hippocampus receive activating signals, they first induce the expression of the transcription factor Ascl1 and only subsequently exit quiescence. Moreover, lowering Ascl1 expression reduces the proliferation rate of hippocampal stem cells, and inactivating Ascl1 blocks quiescence exit completely, rendering them unresponsive to activating stimuli. Ascl1 promotes the proliferation of hippocampal stem cells by directly regulating the expression of cell-cycle regulatory genes. Ascl1 is similarly required for stem cell activation in the adult subventricular zone. Our results support a model whereby Ascl1 integrates inputs from both stimulatory and inhibitory signals and converts them into a transcriptional program activating adult neural stem cells.

  10. A Transcriptional Mechanism Integrating Inputs from Extracellular Signals to Activate Hippocampal Stem Cells

    PubMed Central

    Andersen, Jimena; Urbán, Noelia; Achimastou, Angeliki; Ito, Ayako; Simic, Milesa; Ullom, Kristy; Martynoga, Ben; Lebel, Mélanie; Göritz, Christian; Frisén, Jonas; Nakafuku, Masato; Guillemot, François

    2014-01-01

    Summary The activity of adult stem cells is regulated by signals emanating from the surrounding tissue. Many niche signals have been identified, but it is unclear how they influence the choice of stem cells to remain quiescent or divide. Here we show that when stem cells of the adult hippocampus receive activating signals, they first induce the expression of the transcription factor Ascl1 and only subsequently exit quiescence. Moreover, lowering Ascl1 expression reduces the proliferation rate of hippocampal stem cells, and inactivating Ascl1 blocks quiescence exit completely, rendering them unresponsive to activating stimuli. Ascl1 promotes the proliferation of hippocampal stem cells by directly regulating the expression of cell-cycle regulatory genes. Ascl1 is similarly required for stem cell activation in the adult subventricular zone. Our results support a model whereby Ascl1 integrates inputs from both stimulatory and inhibitory signals and converts them into a transcriptional program activating adult neural stem cells. PMID:25189209

  11. 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.

  12. 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.

  13. 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

  14. Characterization of sacral interneurons that mediate activation of locomotor pattern generators by sacrocaudal afferent input.

    PubMed

    Etlin, Alex; Finkel, Eran; Mor, Yoav; O'Donovan, Michael J; Anglister, Lili; Lev-Tov, Aharon

    2013-01-01

    Identification of the neural pathways involved in retraining the spinal central pattern generators (CPGs) by afferent input in the absence of descending supraspinal control is feasible in isolated rodent spinal cords where the locomotor CPGs are potently activated by sacrocaudal afferent (SCA) input. Here we study the involvement of sacral neurons projecting rostrally through the ventral funiculi (VF) in activation of the CPGs by sensory stimulation. Fluorescent labeling and immunostaining showed that VF neurons are innervated by primary afferents immunoreactive for vesicular glutamate transporters 1 and 2 and by intraspinal neurons. Calcium imaging revealed that 55% of the VF neurons were activated by SCA stimulation. The activity of VF neurons and the sacral and lumbar CPGs was abolished when non-NMDA receptors in the sacral segments were blocked by the antagonist CNQX. When sacral NMDA receptors were blocked by APV, the sacral CPGs were suppressed, VF neurons with nonrhythmic activity were recruited and a moderate-drive locomotor rhythm developed during SCA stimulation. In contrast, when the sacral CPGs were activated by SCA stimulation, rhythmic and nonrhythmic VF neurons were recruited and the locomotor rhythm was most powerful. The activity of 73 and 27% of the rhythmic VF neurons was in-phase with the ipsilateral and contralateral motor output, respectively. Collectively, our studies indicate that sacral VF neurons serve as a major link between SCA and the hindlimb CPGs and that the ability of SCA to induce stepping can be enhanced by the sacral CPGs. The nature of the ascending drive to lumbar CPGs, the identity of subpopulations of VF neurons, and their potential role in activating the locomotor rhythm are discussed. PMID:23303951

  15. 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.

  16. 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

  17. A Current-Mode Buck DC-DC Converter with Frequency Characteristics Independent of Input and Output Voltages Using a Quadratic Compensation Slope

    NASA Astrophysics Data System (ADS)

    Sai, Toru; Sugimoto, Yasuhiro

    By using a quadratic compensation slope, a CMOS current-mode buck DC-DC converter with constant frequency characteristics over wide input and output voltage ranges has been developed. The use of a quadratic slope instead of a conventional linear slope makes both the damping factor in the transfer function and the frequency bandwidth of the current feedback loop independent of the converter's output voltage settings. When the coefficient of the quadratic slope is chosen to be dependent on the input voltage settings, the damping factor in the transfer function and the frequency bandwidth of the current feedback loop both become independent of the input voltage settings. Thus, both the input and output voltage dependences in the current feedback loop are eliminated, the frequency characteristics become constant, and the frequency bandwidth is maximized. To verify the effectiveness of a quadratic compensation slope with a coefficient that is dependent on the input voltage in a buck DC-DC converter, we fabricated a test chip using a 0.18µm high-voltage CMOS process. The evaluation results show that the frequency characteristics of both the total feedback loop and the current feedback loop are constant even when the input and output voltages are changed from 2.5V to 7V and from 0.5V to 5.6V, respectively, using a 3MHz clock.

  18. 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

  19. Precise control of plant stem cell activity through parallel regulatory inputs.

    PubMed

    Bennett, Tom; van den Toorn, Albert; Willemsen, Viola; Scheres, Ben

    2014-11-01

    The regulation of columella stem cell activity in the Arabidopsis root cap by a nearby organizing centre, the quiescent centre, has been a key example of the stem cell niche paradigm in plants. Here, we investigate interactions between transcription factors that have been shown to regulate columella stem cells using a simple quantification method for stem cell activity in the root cap. Genetic and expression analyses reveal that the RETINOBLASTOMA-RELATED protein, the FEZ and SOMBRERO NAC-domain transcription factors, the ARF10 and ARF16 auxin response factors and the quiescent centre-expressed WOX5 homeodomain protein each provide independent inputs to regulate the number of columella stem cells. Given the tight control of columella development, we found that these inputs act in a surprisingly parallel manner. Nevertheless, important points of interaction exist; for example, we demonstrate the repression of SMB activity by non-autonomous action of WOX5. Our results suggest that the developmental progression of columella stem cells may be quantitatively regulated by several more broadly acting transcription factors rather than by a single intrinsic stem cell factor, which raises questions about the special nature of the stem cell state in plants.

  20. Hyperpolarization-activated cation current contributes to spontaneous network activity in developing neocortical cultures.

    PubMed

    Klueva, Julia; Lima, Ana D de; Meis, Susanne; Voigt, Thomas; Munsch, Thomas

    2012-01-01

    The mechanisms underlying spontaneous burst activity (SBA), appearing in networks of embryonic cortical neurons at the end of the first week in vitro, remain elusive. Here we investigated the contribution of the hyperpolarization-activated cation current (I(h)) to SBA in cortical cultures of GAD67-GFP mice. I(h) current could be detected in GFP-positive large GABAergic interneurons (L-INs) and glutamatergic principal neurons (PNs) as early as DIV 5. Under current-clamp conditions, blockers of I(h) current, ZD7288 and Cs⁺, abolished the voltage sag and rebound depolarization. ZD7288 induced a hyperpolarization concomitant with an increase in the membrane input resistance in L-INs and PNs. Voltage-clamp recordings revealed I(h) as slowly activating inward current with a reversal potential close to -50 mV and a mid-activation point around -90 mV. Both, ZD7288 (1-10 μM) and Cs⁺ (1-2 mM) reduced SBA, spontaneous activity-driven Ca²⁺ transients, and frequency as well as amplitude of miniature GABAergic postsynaptic currents. Immunocytochemistry and Western blot demonstrated that HCN1 and HCN2 were the prevalent isoforms of HCN channels expressed in L-INs and PNs. These results suggest an important contribution of HCN channels to the maintenance of SBA in embryonic cortical cultures. PMID:22094222

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

    PubMed

    Kwon, Jeong-Tae; Nakajima, Ryuichi; Kim, Hyung-Su; Jeong, Yire; Augustine, George J; Han, Jin-Hee

    2014-11-01

    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.

  2. Opening remarks: Current and future activities

    NASA Technical Reports Server (NTRS)

    Davarian, Faramaz

    1993-01-01

    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. An 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.

  3. 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).

  4. 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

  5. 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.

  6. Activation of a lobster motor rhythm-generating network by disinhibition of permissive modulatory inputs.

    PubMed

    Faumont, S; Simmers, J; Meyrand, P

    1998-11-01

    Rhythm generation by the gastric motor network in the stomatogastric ganglion (STG) of the lobster Homarus gammarus is controlled by modulatory projection neurons from rostral commissural ganglia (CoGs); blocking action potential conduction in these inputs to the STG of a stomatogastric nervous system in vitro rapidly renders the gastric network silent. However, exposure of the CoGs to low Ca2+ saline to block chemical synapses activates a spontaneously silent gastric network or enhances an ongoing gastric rhythm. A similar permissive effect was observed when picrotoxin was also superfused on these ganglia. We conclude that in the CoGs continuous synaptic inhibition is exerted on modulatory projection neuron(s) and that release from this inhibition allows strong activation of the gastric network. PMID:9819280

  7. Organization of olivocerebellar activity in the absence of excitatory glutamatergic input.

    PubMed

    Lang, E J

    2001-03-01

    The olivocerebellar system has been proposed to function as a timing device for motor coordination in which inferior olivary neurons act as coupled oscillators that spontaneously generate rhythmic and synchronous activity. However, the inferior olive receives excitatory afferents, which can also drive the activity of these neurons. The extent to which the olivocerebellar system can intrinsically generate synchronous activity and olivary neurons act as neuronal oscillators has not been determined. To investigate this issue, multiple electrode recordings of complex spike (CS) activity were obtained from 236 crus 2a Purkinje cells in anesthetized rats. Intraolivary injections of the glutamate antagonists 6-cyano-7-nitroquinoxaline-2,3-dione or 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide disodium were made, and the resulting changes in CS activity were determined. Loss of evoked CS responses to motor cortex stimulation or perioral tactile stimulation was used to measure the efficacy of the block. Block of glutamatergic input decreased the average CS firing rate by approximately 50% but did not abolish spontaneous CS activity. The remaining CS activity was significantly more rhythmic than that in control. The patterns of synchrony were similar to those found in control conditions (i.e., synchronous CSs primarily occurred among Purkinje cells located within the same approximately 250-microm-wide rostrocaudally oriented cortical strip); however, this normal banding pattern was enhanced. These changes in CS activity were not observed with vehicle injections. The results suggest that excitatory afferent activity disrupts olivary oscillations and support the hypotheses that olivary neurons are capable of acting as neuronal oscillators and that synchronous CS activity results from electrotonic coupling of olivary neurons.

  8. 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

  9. 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

  10. Opposing Effects of Intrinsic Conductance and Correlated Synaptic Input on Vm-Fluctuations during Network Activity

    PubMed Central

    Kolind, Jens; Hounsgaard, Jørn; Berg, Rune W.

    2012-01-01

    Neurons often receive massive concurrent bombardment of synaptic inhibition and excitation during functional network activity. This increases membrane conductance and causes fluctuations in membrane potential (Vm) and spike timing. The conductance increase is commonly attributed to synaptic conductance, but also includes the intrinsic conductances recruited during network activity. These two sources of conductance have contrasting dynamic properties at sub-threshold membrane potentials. Synaptic transmitter gated conductance changes abruptly and briefly with each presynaptic action potential. If the spikes arrive at random times the changes in synaptic conductance are therefore stochastic and rapid during intense network activity. In comparison, sub-threshold intrinsic conductances vary smoothly in time. In the present study this discrepancy is investigated using two conductance-based models: a (1) compartment model and a (2) compartment with realistic slow intrinsic conductances. We examine the effects of varying the relative contributions of non-fluctuating intrinsic conductance with fluctuating concurrent inhibitory and excitatory synaptic conductance. For given levels of correlation in the synaptic input we find that the magnitude of the membrane fluctuations uniquely determines the relative contribution of synaptic and intrinsic conductance. We also quantify how Vm-fluctuations vary with synaptic correlations for fixed ratios of synaptic and intrinsic conductance. Interestingly, the levels of Vm -fluctuations and conductance observed experimentally during functional network activity leave little room for intrinsic conductance to contribute. Even without intrinsic conductances the variance in Vm -fluctuations can only be explained by a high degree of correlated firing among presynaptic neurons. PMID:22783184

  11. Anthropogenic activities have contributed moderately to increased inputs of organic materials in marginal seas off China.

    PubMed

    Liu, Liang-Ying; Wei, Gao-Ling; Wang, Ji-Zhong; Guan, Yu-Feng; Wong, Charles S; Wu, Feng-Chang; Zeng, Eddy Y

    2013-10-15

    Sediment has been recognized as a gigantic sink of organic materials and therefore can record temporal input trends. To examine the impact of anthropogenic activities on the marginal seas off China, sediment cores were collected from the Yellow Sea, the inner shelf of the East China Sea (ECS), and the South China Sea (SCS) to investigate the sources and spatial and temporal variations of organic materials, i.e., total organic carbon (TOC) and aliphatic hydrocarbons. The concentration ranges of TOC were 0.5-1.29, 0.63-0.83, and 0.33-0.85%, while those of Σn-C14-35 (sum of n-alkanes with carbon numbers of 14-35) were 0.08-1.5, 0.13-1.97, and 0.35-0.96 μg/g dry weight in sediment cores from the Yellow Sea, ECS inner shelf, and the SCS, respectively. Terrestrial higher plants were an important source of aliphatic hydrocarbons in marine sediments off China. The spatial distribution of Σn-C14-35 concentrations and source diagnostic ratios suggested a greater load of terrestrial organic materials in the Yellow Sea than in the ECS and SCS. Temporally, TOC and Σn-C14-35 concentrations increased with time and peaked at either the surface or immediate subsurface layers. This increase was probably reflective of elevated inputs of organic materials to marginal seas off China in recent years, and attributed partly to the impacts of intensified anthropogenic activities in mainland China. Source diagnostics also suggested that aliphatic hydrocarbons were mainly derived from biogenic sources, with a minority in surface sediment layers from petroleum sources, consistent with the above-mentioned postulation.

  12. 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

  13. Modulation of postsynaptic activities of thalamic lateral geniculate neurons by spontaneous changes in number of retinal inputs in chronic cats. 1. Input-output relations.

    PubMed

    Fourment, A; Hirsch, J C; Marc, M E; Guidet, C

    1984-06-01

    The experiments were designed to explore the role of retinal inputs compared with that of the behavioral state in the modulation of the output of thalamic lateral geniculate neurons during sleep and wakefulness in cats with intact visual pathways. We made the following assumptions: the retinal dark discharge, while showing spontaneous pauses in activity, does not vary with the behavioral state; the optic tract inputs postsynaptically elicit subthreshold activities called S-potentials which in turn generate spikes, the degree of transformation being dependent on the level of alertness. On the basis of these assumptions, it could be expected that changes in retinal input frequency would modify the rate of the S-potentials. Therefore the effect of spontaneous decreases in frequency of S-potentials on the spike rate and pattern was examined in juxta- and intracellular recordings from chronically implanted cats during natural sleep and wakefulness. During quiet wakefulness and light slow-wave sleep, lateral geniculate relay neurons normally displayed numerous S-potentials associated with a moderate firing rate. Many neurons occasionally showed transient reductions in frequency of the S-potentials and an oversimplification of the discharges which combined a decreased rate with a prevalent rhythmical burst pattern. Antidromic responsiveness remained unchanged. The oscillatory periods recurred two to six times without any alteration in the control state level. They were not observed throughout wakefulness and paradoxical sleep, during which neuronal activity combined a high spike rate with a low S-potential rate. The modifications were confirmed by computation of the mean rates and of the inter-event intervals. The transfer ratio (spikes/S-potentials + spikes) significantly increased both during the oscillatory periods poor in S-potentials of quiet wakefulness and during active wakefulness. But the correlation between the transfer ratio and the spike frequency, which was

  14. Oscillatory activity in developing prefrontal networks results from theta-gamma-modulated synaptic inputs.

    PubMed

    Bitzenhofer, Sebastian H; Sieben, Kay; Siebert, Kai D; Spehr, Marc; Hanganu-Opatz, Ileana L

    2015-04-21

    The hippocampus-driven entrainment of neonatal prefrontal circuits in theta-gamma oscillations contributes to the maturation of cognitive abilities, yet the underlying synaptic mechanisms are still unknown. Here we combine patch-clamp recordings from morphologically and neurochemically characterized layer V pyramidal neurons and interneurons in vivo, with extracellular recordings from the prelimbic cortex (PL) of awake and lightly anesthetized neonatal rats, to elucidate the synaptic framework of early network oscillations. We demonstrate that all neurons spontaneously fire bursts of action potentials. They receive barrages of fast and slow glutamatergic as well as GABAergic synaptic inputs. Oscillatory theta activity results from long-range coupling of pyramidal neurons, presumably within prelimbic-hippocampal circuits, and from local interactions between interneurons. In contrast, beta-low gamma activity requires external glutamatergic drive on prelimbic interneurons. High-frequency oscillations in layer V are independent of interactions at chemical synapses. Thus, specific theta-gamma-modulated synaptic interactions represent the substrate of network oscillations in the developing PL. PMID:25865885

  15. Gravity Field Determination at AIUB: Current Activities

    NASA Astrophysics Data System (ADS)

    Jaeggi, A.; Beutler, G.; Prange, L.; Meyer, U.; Mervart, L.; Dach, R.; Rummel, R.; Gruber, T.

    2009-04-01

    Research on global gravity field recovery from satellite missions such as CHAMP and GRACE was initiated at the Astronomical Institute of the University of Bern (AIUB, Switzerland) in the year 2006. Since September 2007, the activities were extended in the framework of the project Satellite Geodesy sponsored by the Institute for Advanced Study (IAS) of the Technical University of Munich (TUM, Germany). Gravity field recovery at AIUB is rigorously treated as an extended orbit determination problem. This so-called Celestial Mechanics Approach is applied to GPS high-low satellite-to-satellite tracking (hl-SST) data of low Earth orbiters (LEOs), via the use of kinematic LEO positions, and to K-band low-low satellite-to-satellite tracking (ll-SST) data of the GRACE mission. Kinematic LEO positions are determined at AIUB using the GPS orbit and clock products of the Center for Orbit Determination in Europe (CODE). CODE is an analysis center of the International GNSS Service (IGS) and is operated by AIUB in cooperation with the Federal Office of Topography (swisstopo, Switzerland), the Federal Office of Cartography and Geodesy (BKG, Germany), and the Institute of Astronomical and Physical Geodesy (IAPG) of the Technical University of Munich. We will describe the currently implemented refined processing strategies of the Celestial Mechanics Approach and present selected results. The benefits of our rigorous approach are demonstrated by comparisons of our latest annual GRACE ll-SST solutions and multi-annual CHAMP hl-SST solutions with the results of other groups and by external validations. A special focus is on the relevance of background models for GRACE gravity field determination when using K-band data, and on the impact of systematic errors in GPS observations when performing gravity field recovery with hl-SST observations.

  16. Does Kaniso activate CASINO?: input coding schemes and phonology in visual-word recognition.

    PubMed

    Acha, Joana; Perea, Manuel

    2010-01-01

    Most recent input coding schemes in visual-word recognition assume that letter position coding is orthographic rather than phonological in nature (e.g., SOLAR, open-bigram, SERIOL, and overlap). This assumption has been drawn - in part - by the fact that the transposed-letter effect (e.g., caniso activates CASINO) seems to be (mostly) insensitive to phonological manipulations (e.g., Perea & Carreiras, 2006, 2008; Perea & Pérez, 2009). However, one could argue that the lack of a phonological effect in prior research was due to the fact that the manipulation always occurred in internal letter positions - note that phonological effects tend to be stronger for the initial syllable (Carreiras, Ferrand, Grainger, & Perea, 2005). To reexamine this issue, we conducted a masked priming lexical decision experiment in which we compared the priming effect for transposed-letter pairs (e.g., caniso-CASINO vs. caviro-CASINO) and for pseudohomophone transposed-letter pairs (kaniso-CASINO vs. kaviro-CASINO). Results showed a transposed-letter priming effect for the correctly spelled pairs, but not for the pseudohomophone pairs. This is consistent with the view that letter position coding is (primarily) orthographic in nature.

  17. 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.

  18. 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

  19. 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

  20. 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

  1. Physical activity and mental health: current concepts.

    PubMed

    Paluska, S A; Schwenk, T L

    2000-03-01

    Physical activity may play an important role in the management of mild-to-moderate mental health diseases, especially depression and anxiety. Although people with depression tend to be less physically active than non-depressed individuals, increased aerobic exercise or strength training has been shown to reduce depressive symptoms significantly. However, habitual physical activity has not been shown to prevent the onset of depression. Anxiety symptoms and panic disorder also improve with regular exercise, and beneficial effects appear to equal meditation or relaxation. In general, acute anxiety responds better to exercise than chronic anxiety. Studies of older adults and adolescents with depression or anxiety have been limited, but physical activity appears beneficial to these populations as well. Excessive physical activity may lead to overtraining and generate psychological symptoms that mimic depression. Several differing psychological and physiological mechanisms have been proposed to explain the effect of physical activity on mental health disorders. Well controlled studies are needed to clarify the mental health benefits of exercise among various populations and to address directly processes underlying the benefits of exercise on mental health.

  2. 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.

  3. 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…

  4. 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.

  5. 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.

  6. 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

  7. 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

    2016-01-19

    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.

  8. 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.

  9. 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

  10. Trace element inputs into soils by anthropogenic activities and implications for human health.

    PubMed

    Senesi, G S; Baldassarre, G; Senesi, N; Radina, B

    1999-07-01

    Trace element definition and functions, and inputs into soils from the most important anthropogenic sources, related and not related to agricultural practices, of general and local or incidental concern, are discussed in the first part of this review. Trace element inputs include those from commercial fertilizers, liming materials and agrochemicals, sewage sludges and other wastes used as soil amendments, irrigation waters, and atmospheric depositions from urban, industrial, and other sources. In the second part of the review, the most important ascertained effects of soil trace elements on human health are presented. The possible relations found between some specific soil trace elements, such as Cd, Se, As and others, and cancer incidence and mortality, and diffusion of other important human diseases are reviewed. Brief conclusions and recommendations conclude this review.

  11. Modeling the impact of common noise inputs on the network activity of retinal ganglion cells

    PubMed Central

    Ahmadian, Yashar; Shlens, Jonathon; Pillow, Jonathan W.; Kulkarni, Jayant; Litke, Alan M.; Chichilnisky, E. J.; Simoncelli, Eero; Paninski, Liam

    2013-01-01

    Synchronized spontaneous firing among retinal ganglion cells (RGCs), on timescales faster than visual responses, has been reported in many studies. Two candidate mechanisms of synchronized firing include direct coupling and shared noisy inputs. In neighboring parasol cells of primate retina, which exhibit rapid synchronized firing that has been studied extensively, recent experimental work indicates that direct electrical or synaptic coupling is weak, but shared synaptic input in the absence of modulated stimuli is strong. However, previous modeling efforts have not accounted for this aspect of firing in the parasol cell population. Here we develop a new model that incorporates the effects of common noise, and apply it to analyze the light responses and synchronized firing of a large, densely-sampled network of over 250 simultaneously recorded parasol cells. We use a generalized linear model in which the spike rate in each cell is determined by the linear combination of the spatio-temporally filtered visual input, the temporally filtered prior spikes of that cell, and unobserved sources representing common noise. The model accurately captures the statistical structure of the spike trains and the encoding of the visual stimulus, without the direct coupling assumption present in previous modeling work. Finally, we examined the problem of decoding the visual stimulus from the spike train given the estimated parameters. The common-noise model produces Bayesian decoding performance as accurate as that of a model with direct coupling, but with significantly more robustness to spike timing perturbations. PMID:22203465

  12. Modeling the impact of common noise inputs on the network activity of retinal ganglion cells.

    PubMed

    Vidne, Michael; Ahmadian, Yashar; Shlens, Jonathon; Pillow, Jonathan W; Kulkarni, Jayant; Litke, Alan M; Chichilnisky, E J; Simoncelli, Eero; Paninski, Liam

    2012-08-01

    Synchronized spontaneous firing among retinal ganglion cells (RGCs), on timescales faster than visual responses, has been reported in many studies. Two candidate mechanisms of synchronized firing include direct coupling and shared noisy inputs. In neighboring parasol cells of primate retina, which exhibit rapid synchronized firing that has been studied extensively, recent experimental work indicates that direct electrical or synaptic coupling is weak, but shared synaptic input in the absence of modulated stimuli is strong. However, previous modeling efforts have not accounted for this aspect of firing in the parasol cell population. Here we develop a new model that incorporates the effects of common noise, and apply it to analyze the light responses and synchronized firing of a large, densely-sampled network of over 250 simultaneously recorded parasol cells. We use a generalized linear model in which the spike rate in each cell is determined by the linear combination of the spatio-temporally filtered visual input, the temporally filtered prior spikes of that cell, and unobserved sources representing common noise. The model accurately captures the statistical structure of the spike trains and the encoding of the visual stimulus, without the direct coupling assumption present in previous modeling work. Finally, we examined the problem of decoding the visual stimulus from the spike train given the estimated parameters. The common-noise model produces Bayesian decoding performance as accurate as that of a model with direct coupling, but with significantly more robustness to spike timing perturbations.

  13. 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

  14. Subthreshold vestibular reflex effects in seated humans can contribute to soleus activation when combined with cutaneous inputs.

    PubMed

    Thomas, Kristen E; Bent, Leah R

    2013-01-01

    The integration of vestibular and somatosensory information for the control of lower limb musculature remains elusive. To determine whether a subthreshold vestibular input influences the cutaneous evoked response, the isometric EMG activity in the posturally inactive soleus muscles of 13 healthy, seated subjects was collected. Vestibular afferents were activated using galvanic vestibular stimulation (GVS; 1.8-2.5mA, 500ms), while percutaneous electrical stimulation was delivered to the distal tibial nerve (11ms train of 3 × 1.0 ms pulses, 200Hz) to activate foot sole skin afferents. GVS elicited responses in soleus both independently and when combined with cutaneous stimulation. The responses to the combined sensory input showed an interaction between the two sensory modalities to influence muscle activation. Of note is the presence of significant muscle modulation in the combined condition, where subthreshold vestibular inputs altered the outcome of the cutaneous reflex response. This finding has implications for individuals with sensory deficiency. In the case of an absent or deficient sensory modality, balance protective reflexes to maintain postural equilibrium may be enhanced with targeted sensory augmentation.

  15. Cholinergic receptor activation induces a relative facilitation of synaptic responses in the entorhinal cortex during theta- and gamma-frequency stimulation of parasubicular inputs.

    PubMed

    Sparks, D W; Chapman, C A

    2013-01-29

    The parasubiculum sends its single major output to layer II of the entorhinal cortex, and it may therefore interact with inputs to the entorhinal cortex from other cortical areas, and help to shape the activity of layer II entorhinal cells that project to the hippocampal formation. Cholinergic inputs are thought to contribute to the generation of theta- and gamma-frequency activities in the parasubiculum and entorhinal cortex, and the present study assessed how cholinergic receptor activation affects synaptic responses of the entorhinal cortex to theta- and gamma-frequency stimulation. Depth profiles of field excitatory postsynaptic potentials (fEPSPs) in acute brain slices showed a short-latency negative fEPSP in layer II, consistent with the activation of excitatory synaptic inputs to layer II. Application of the cholinergic agonist carbachol (CCh) suppressed synaptic responses and enhanced paired-pulse facilitation. CCh also resulted in a marked relative facilitation of synaptic responses evoked during short 5-pulse trains of stimulation at both theta- and gamma-frequencies. Application of the M(1) antagonist pirenzepine, but not the M(2) antagonist methoctramine, blocked the facilitation of responses. Inhibition of the M-current or block of GABA(B) receptors had no effect, but the facilitation effect was partially blocked by the N-methyl-d-aspartate (NMDA) antagonist APV, indicating that NMDA receptors play a role. Application of ZD7288, a selective inhibitor of the hyperpolarization-activated cationic current I(h), almost completely blocked the relative facilitation of responses, and the less potent I(h)-blocker Cs(+) also resulted in a partial block. The relative facilitation of synaptic responses induced by CCh is therefore likely mediated by multiple mechanisms including the cholinergic suppression of transmitter release that enhances transmitter availability during repetitive stimulation, NMDA receptor-mediated effects on pre- or postsynaptic function, and

  16. 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.

  17. How Effective Are Affective Activities? Relative Benefits of Two Types of Structured Input Activities as Part of a Computer-Delivered Lesson on the Spanish Subjunctive

    ERIC Educational Resources Information Center

    Henshaw, Florencia

    2012-01-01

    Proponents of Processing Instruction (VanPatten, 2005) claim that learners benefit most when presented with both referential and affective structured input activities. Following a classic pretest-posttest design, the present study investigates the role of these two types of activities on the learning of the Spanish subjunctive. Groups differed…

  18. Peripheral nerve injury activates convergent nociceptive input to dorsal horn neurons from neighboring intact nerve.

    PubMed

    Terayama, Ryuji; Yamamoto, Yuya; Kishimoto, Noriko; Maruhama, Kotaro; Mizutani, Masahide; Iida, Seiji; Sugimoto, Tomosada

    2015-04-01

    Previous studies demonstrated that peripheral nerve injury induced excessive nociceptive response of spinal cord dorsal horn neurons and such change has been proposed to reflect the development of neuropathic pain state. The aim of this study was to examine the spinal dorsal horn for convergence of nociceptive input to second-order neurons deafferented by peripheral nerve injury. Double immunofluorescence labeling for c-Fos and phosphorylated extracellular signal-regulated kinase (p-ERK) was performed to detect convergent synaptic input to spinal dorsal horn neurons after the saphenous nerve injury. c-Fos expression and the phosphorylation of ERK were induced by noxious heat stimulation of the hindpaw and by electrical stimulation of the injured or uninjured saphenous nerve, respectively. Within the central terminal field of the saphenous nerve, the number of c-Fos protein-like immunoreactive (c-Fos-IR) cell profiles was significantly decreased at 3 days and returned to the control level by 14 days after the injury. p-ERK immunoreactive (p-ERK-IR) cell profiles were distributed in the central terminal field of the saphenous nerve, and the topographic distribution pattern and number of such p-ERK-IR cell profiles remained unchanged after the nerve injury. The time course of changes in the number of double-labeled cell profiles was similar to that of c-Fos-IR cell profiles after the injury. These results indicate that convergent primary nociceptive input through neighboring intact nerves contributes to increased responsiveness of spinal dorsal horn nociceptive neurons.

  19. 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

  20. A synaptic input portal for a mapped clock oscillator model of neuronal electrical rhythmic activity.

    PubMed

    Zariffa, José; Ebden, Mark; Bardakjian, Berj L

    2004-09-01

    Neuronal electrical oscillations play a central role in a variety of situations, such as epilepsy and learning. The mapped clock oscillator (MCO) model is a general model of transmembrane voltage oscillations in excitable cells. In order to be able to investigate the behaviour of neuronal oscillator populations, we present a neuronal version of the model. The neuronal MCO includes an extra input portal, the synaptic portal, which can reflect the biological relationships in a chemical synapse between the frequency of the presynaptic action potentials and the postsynaptic resting level, which in turn affects the frequency of the postsynaptic potentials. We propose that the synaptic input-output relationship must include a power function in order to be able to reproduce physiological behaviour such as resting level saturation. One linear and two power functions (Butterworth and sigmoidal) are investigated, using the case of an inhibitory synapse. The linear relation was not able to produce physiologically plausible behaviour, whereas both the power function examples were appropriate. The resulting neuronal MCO model can be tailored to a variety of neuronal cell types, and can be used to investigate complex population behaviour, such as the influence of network topology and stochastic resonance.

  1. 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.

  2. 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.

  3. 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.

  4. Variations in Solar Activity and Irradiance and Their Implications for Energy Input Into the Terrestrial Atmosphere

    NASA Astrophysics Data System (ADS)

    Parker, Daryl Gray

    This dissertation presents research into the question of how variations in the physical properties of resolved solar magnetic surface features combine to produce variations in the physical properties of the integrated Sun and the possible impacts of those variations on the terrestrial climate system. The core approach to the research was development of techniques to apply automated Bayesian statistical pattern recognition methods as implemented in the AutoClass software to magnetic and intensity-like solar images from the Mount Wilson Solar Observatory (MWO) 150 Foot Solar Telescope. The goals were to: (1) identify in an objective and quantifiable manner the solar surface features responsible for changes in solar irradiance, (2) enhance understanding of the evolution of these features and the resultant solar irradiance variations over the most recent solar cycles, (3) develop methods to identify the specific features responsible for variations in specific wavelengths, (4) use global observations of global solar irradiance indices to identify the spatially resolved features which contribute to them, (5) attempt to apply these results to specific topics of current interest in solar-stellar astronomy. Using these techniques, a method was developed to identify classes of features from thousands of MWO solar images based on the per pixel values of absolute magnetic field strength and an intensity measure known as a "ratio-gram" in MWO images. Using these classes along with observations from independent, usually satellite based, sources in different wavelengths, models were constructed of total solar irradiance (TSI) and solar UV indices. These models were able to reproduce with high correlations solar observations in a number of different solar wavelengths. These classes were also used to construct images mapping different wavelength emissions to the areas to the solar surface features from which they originated. These techniques proved able to reproduce with high

  5. 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.

  6. Acetylcholine, theta-rhythm and activity of hippocampal neurons in the rabbit--III. Cortical input.

    PubMed

    Vinogradova, O S; Brazhnik, E S; Stafekhina, V S; Kitchigina, V F

    1993-04-01

    Cholinergic modulation of single cell responses and field potentials evoked in the hippocampus by electrical stimulation of the perforant path and mossy fibres was investigated in two groups of chronic unanesthetized rabbits--with intact hippocampus and with basally undercut septum (without ascending medial forebrain bundle afferents). In both groups of animals responses to stimulation were blocked or significantly depressed by i.v. physostigmine injection in many neurons (50% in the intact hippocampus and 69% in the hippocampus without medial forebrain bundle). In minor groups of neurons (10 and 8%, respectively), facilitation of responses was observed. Scopolamine restored initial responsiveness of hippocampal neurons and augmented effects of stimulation in some of them. The effect of physostigmine was reproduced by stimulation of the medial septum. Depressive influence of medial septal area stimulation was increased by physostigmine and blocked by scopolamine. Population spikes evoked by stimulation of the perforant path of the intact group were equally suppressed (by 43%) during sensory stimulation evoking natural theta, after physostigmine and after medial septal area stimulation. In the group of animals without medial forebrain bundle these influences resulted in a complete suppression of field potentials; scopolamine restored them. It is concluded that the main function of the septohippocampal cholinergic input consists of filtering out the signals appearing at the background of theta-rhythm triggered by a previous signal, thus preventing their interference with its processing and registration. PMID:8506031

  7. Activity and function recognition for moving and static objects in urban environments from wide-area persistent surveillance inputs

    NASA Astrophysics Data System (ADS)

    Levchuk, Georgiy; Bobick, Aaron; Jones, Eric

    2010-04-01

    In this paper, we describe results from experimental analysis of a model designed to recognize activities and functions of moving and static objects from low-resolution wide-area video inputs. Our model is based on representing the activities and functions using three variables: (i) time; (ii) space; and (iii) structures. The activity and function recognition is achieved by imposing lexical, syntactic, and semantic constraints on the lower-level event sequences. In the reported research, we have evaluated the utility and sensitivity of several algorithms derived from natural language processing and pattern recognition domains. We achieved high recognition accuracy for a wide range of activity and function types in the experiments using Electro-Optical (EO) imagery collected by Wide Area Airborne Surveillance (WAAS) platform.

  8. 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

  9. 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.

  10. Optimisation of active suspension control inputs for improved vehicle handling performance

    NASA Astrophysics Data System (ADS)

    Čorić, Mirko; Deur, Joško; Kasać, Josip; Tseng, H. Eric; Hrovat, Davor

    2016-11-01

    Active suspension is commonly considered under the framework of vertical vehicle dynamics control aimed at improvements in ride comfort. This paper uses a collocation-type control variable optimisation tool to investigate to which extent the fully active suspension (FAS) application can be broaden to the task of vehicle handling/cornering control. The optimisation approach is firstly applied to solely FAS actuator configurations and three types of double lane-change manoeuvres. The obtained optimisation results are used to gain insights into different control mechanisms that are used by FAS to improve the handling performance in terms of path following error reduction. For the same manoeuvres the FAS performance is compared with the performance of different active steering and active differential actuators. The optimisation study is finally extended to combined FAS and active front- and/or rear-steering configurations to investigate if they can use their complementary control authorities (over the vertical and lateral vehicle dynamics, respectively) to further improve the handling performance.

  11. 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.

  12. 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

  13. 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

  14. 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...

  15. 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

  16. Activity and neuromodulatory input contribute to the recovery of rhythmic output after decentralization in a central pattern generator.

    PubMed

    Zhang, Yili; Khorkova, Olga; Rodriguez, Rosa; Golowasch, Jorge; Golowaschi, Jorge

    2009-01-01

    Central pattern generators (CPGs) are neuronal networks that control vitally important rhythmic behaviors including breathing, heartbeat, and digestion. Understanding how CPGs recover activity after their rhythmic activity is disrupted has important theoretical and practical implications. Previous experimental and modeling studies indicated that rhythm recovery after central neuromodulatory input loss (decentralization) could be based entirely on activity-dependent mechanisms, but recent evidence of long-term conductance regulation by neuromodulators suggest that neuromodulator-dependent mechanisms may also be involved. Here we examined the effects of altering activity and the neuromodulatory environment before decentralization of the pyloric CPG in Cancer borealis on the initial phase of rhythmic activity recovery after decentralization. We found that pretreatments altering the network activity through shifting the ionic balance or the membrane potential of pyloric pacemaker neurons reduced the delay of recovery initiation after decentralization, consistent with the recovery process being triggered already during the pretreatment period through an activity-dependent mechanism. However, we observed that pretreatment with neuromodulators GABA and proctolin, acting via metabotropic receptors, also affected the initial phase of the recovery of pyloric activity after decentralization. Their distinct effects appear to result from interactions of their metabotropic effects with their effects on neuronal activity. Thus we show that the initial phase of the recovery process can be accounted for by the existence of distinct activity-and neuromodulator-dependent pathways. We propose a computational model that includes activity- and neuromodulator-dependent mechanisms of the activity recovery process, which successfully explains the experimental observations and predicts the results of key biological experiments.

  17. Separate inputs modulate phosphorylation-dependent and -independent type VI secretion activation

    PubMed Central

    Silverman, Julie M.; Austin, Laura S.; Hsu, FoSheng; Hicks, Kevin G.; Hood, Rachel D.; Mougous, Joseph D.

    2013-01-01

    Summary Productive intercellular delivery of cargo by secretory systems requires exquisite temporal and spatial choreography. Our laboratory has demonstrated that the hemolysin co-regulated secretion island I (HSI-I)-encoded type VI secretion system (H1-T6SS) of Pseudomonas aeruginosa transfers effector proteins to other bacterial cells. The activity of these effectors requires cell contact-dependent delivery by the secretion apparatus, and thus their export is highly repressed under planktonic growth conditions. Here we define regulatory pathways that orchestrate efficient secretion by this system. We identified a T6S-associated protein, TagF, as a posttranslational repressor of the H1-T6SS. Strains activated by TagF derepression or stimulation of a previously identified threonine phosphorylation pathway (TPP) share the property of secretory ATPase recruitment to the T6S apparatus, yet display different effector output levels and genetic requirements for their export. We also found that the pathways respond to distinct stimuli; we identified surface growth as a physiological cue that activates the H1-T6SS exclusively through the TPP. Coordination of posttranslational triggering with cell contact-promoting growth conditions provides a mechanism for the T6SS to avoid wasteful release of effectors. PMID:22017253

  18. 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

  19. Activation of the Tonic GABAC Receptor Current in Retinal Bipolar Cell Terminals by Nonvesicular GABA Release

    PubMed Central

    Jones, S. M.; Palmer, M. J.

    2009-01-01

    Within the second synaptic layer of the retina, bipolar cell (BC) output to ganglion cells is regulated by inhibitory input to BC axon terminals. GABAA receptors (GABAARs) mediate rapid synaptic currents in BC terminals, whereas GABAC receptors (GABACRs) mediate slow evoked currents and a tonic current, which is strongly regulated by GAT-1 GABA transporters. We have used voltage-clamp recordings from BC terminals in goldfish retinal slices to determine the source of GABA for activation of these currents. Inhibition of vesicular release with concanamycin A or tetanus toxin significantly inhibited GABAAR inhibitory postsynaptic currents and glutamate-evoked GABAAR and GABACR currents but did not reduce the tonic GABACR current, which was also not dependent on extracellular Ca2+. The tonic current was strongly potentiated by inhibition of GABA transaminase, under both normal and Ca2+-free conditions, and was activated by exogenous taurine; however inhibition of taurine transport had little effect. The tonic current was unaffected by GAT-2/3 inhibition and was potentiated by GAT-1 inhibition even in the absence of vesicular release, indicating that it is unlikely to be evoked by reversal of GABA transporters or by ambient GABA. In addition, GABA release does not appear to occur via hemichannels or P2X7 receptors. BC terminals therefore exhibit two forms of GABACR-mediated inhibition, activated by vesicular and by nonvesicular GABA release, which are likely to have distinct functions in visual signal processing. The tonic GABACR current in BC terminals exhibits similar properties to tonic GABAAR and glutamate receptor currents in the brain. PMID:19494193

  20. THE ORIGIN OF NET ELECTRIC CURRENTS IN SOLAR ACTIVE REGIONS

    SciTech Connect

    Dalmasse, K.; Kliem, B.; Török, T.

    2015-09-01

    There is a recurring question in solar physics regarding whether or not electric currents are neutralized in active regions (ARs). This question was recently revisited using three-dimensional (3D) magnetohydrodynamic (MHD) numerical simulations of magnetic flux emergence into the solar atmosphere. Such simulations showed that flux emergence can generate a substantial net current in ARs. Other sources of AR currents are photospheric horizontal flows. Our aim is to determine the conditions for the occurrence of net versus neutralized currents with this second mechanism. Using 3D MHD simulations, we systematically impose line-tied, quasi-static, photospheric twisting and shearing motions to a bipolar potential magnetic field. We find that such flows: (1) produce both direct and return currents, (2) induce very weak compression currents—not observed in 2.5D—in the ambient field present in the close vicinity of the current-carrying field, and (3) can generate force-free magnetic fields with a net current. We demonstrate that neutralized currents are in general produced only in the absence of magnetic shear at the photospheric polarity inversion line—a special condition that is rarely observed. We conclude that  photospheric flows, as magnetic flux emergence, can build up net currents in the solar atmosphere, in agreement with recent observations. These results thus provide support for eruption models based on pre-eruption magnetic fields that possess a net coronal current.

  1. 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.

  2. 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.

  3. 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.

  4. Eukaryotic Elongation Factor 2 Kinase Activity Is Controlled by Multiple Inputs from Oncogenic Signaling

    PubMed Central

    Wang, Xuemin; Regufe da Mota, Sergio; Liu, Rui; Moore, Claire E.; Xie, Jianling; Lanucara, Francesco; Agarwala, Usha; Pyr dit Ruys, Sébastien; Vertommen, Didier; Rider, Mark H.; Eyers, Claire E.

    2014-01-01

    Eukaryotic elongation factor 2 kinase (eEF2K), an atypical calmodulin-dependent protein kinase, phosphorylates and inhibits eEF2, slowing down translation elongation. eEF2K contains an N-terminal catalytic domain, a C-terminal α-helical region and a linker containing several regulatory phosphorylation sites. eEF2K is expressed at high levels in certain cancers, where it may act to help cell survival, e.g., during nutrient starvation. However, it is a negative regulator of protein synthesis and thus cell growth, suggesting that cancer cells may possess mechanisms to inhibit eEF2K under good growth conditions, to allow protein synthesis to proceed. We show here that the mTORC1 pathway and the oncogenic Ras/Raf/MEK/extracellular signal-regulated kinase (ERK) pathway cooperate to restrict eEF2K activity. We identify multiple sites in eEF2K whose phosphorylation is regulated by mTORC1 and/or ERK, including new ones in the linker region. We demonstrate that certain sites are phosphorylated directly by mTOR or ERK. Our data reveal that glycogen synthase kinase 3 signaling also regulates eEF2 phosphorylation. In addition, we show that phosphorylation sites remote from the N-terminal calmodulin-binding motif regulate the phosphorylation of N-terminal sites that control CaM binding. Mutations in the former sites, which occur in cancer cells, cause the activation of eEF2K. eEF2K is thus regulated by a network of oncogenic signaling pathways. PMID:25182533

  5. Dendritic Slow Dynamics Enables Localized Cortical Activity to Switch between Mobile and Immobile Modes with Noisy Background Input

    PubMed Central

    Kurashige, Hiroki; Câteau, Hideyuki

    2011-01-01

    Mounting lines of evidence suggest the significant computational ability of a single neuron empowered by active dendritic dynamics. This motivates us to study what functionality can be acquired by a network of such neurons. The present paper studies how such rich single-neuron dendritic dynamics affects the network dynamics, a question which has scarcely been specifically studied to date. We simulate neurons with active dendrites networked locally like cortical pyramidal neurons, and find that naturally arising localized activity – called a bump – can be in two distinct modes, mobile or immobile. The mode can be switched back and forth by transient input to the cortical network. Interestingly, this functionality arises only if each neuron is equipped with the observed slow dendritic dynamics and with in vivo-like noisy background input. If the bump activity is considered to indicate a point of attention in the sensory areas or to indicate a representation of memory in the storage areas of the cortex, this would imply that the flexible mode switching would be of great potential use for the brain as an information processing device. We derive these conclusions using a natural extension of the conventional field model, which is defined by combining two distinct fields, one representing the somatic population and the other representing the dendritic population. With this tool, we analyze the spatial distribution of the degree of after-spike adaptation and explain how we can understand the presence of the two distinct modes and switching between the modes. We also discuss the possible functional impact of this mode-switching ability. PMID:21931635

  6. 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.

  7. Orexin as an input of circadian system in goldfish: Effects on clock gene expression and locomotor activity rhythms.

    PubMed

    Nisembaum, Laura G; de Pedro, Nuria; Delgado, María J; Sánchez-Bretaño, Aída; Isorna, Esther

    2014-02-01

    Orexins are neuropeptides mainly known for regulating feeding behavior and sleep-wakefulness cycle in vertebrates. Daily variations of orexin-A expression have been reported in fish, with the highest levels preceding feeding time. However, it is unknown if such variations could be related with daily rhythms of clock genes, which form the molecular core of circadian oscillators. The aim of the present study was to identify the possible role of orexin as an input element of the goldfish circadian system. It was investigated the effects of orexin-A (10ng/gbw) intracerebroventricular injections on the expression of clock genes, NPY and ghrelin, as well as on daily locomotor activity rhythms. Goldfish held under 12L:12D photoperiod and injected at midday with orexin or saline, were sacrificed at 1 and 3h post-injection. The analysis of genes expression by qReal Time PCR showed an increment of Per genes in hypothalamus and foregut at 3h post-injection, but not in hindgut and liver. The gBmal1a expression remained unaltered in all the studied tissues. Orexin induced NPY in the hypothalamus and ghrelin in the foregut. Locomotor activity was studied in fish daily injected with orexin for several consecutive days under different experimental conditions. Orexin synchronized locomotor activity in goldfish maintained in 24L and fasting conditions. Present results support a cross-talking between orexin-A and other feeding regulators at central and peripheral level, and suggest, for the first time, a role of this peptide as an input of the circadian system in fish.

  8. Antiepileptic Activity of Preferential Inhibitors of Persistent Sodium Current

    PubMed Central

    Anderson, Lyndsey L.; Thompson, Christopher H.; Hawkins, Nicole A.; Nath, Ravi D.; Petersohn, Adam A.; Rajamani, Sridharan; Bush, William S.; Frankel, Wayne N.; Vanoye, Carlos G.; Kearney, Jennifer A.; George, Alfred L.

    2014-01-01

    Objective Evidence from basic neurophysiology and molecular genetics has implicated persistent sodium current conducted by voltage-gated sodium (NaV) channels as a contributor to the pathogenesis of epilepsy. Many antiepileptic drugs target NaV channels and modulate neuronal excitability mainly by a use-dependent block of transient sodium current, although suppression of persistent current may also contribute to the efficacy of these drugs. We hypothesized that a drug or compound capable of preferential inhibition of persistent sodium current would have antiepileptic activity. Methods We examined the antiepileptic activity of two selective persistent sodium current blockers ranolazine, an FDA-approved drug for treatment of angina pectoris, and GS967, a novel compound with more potent effects on persistent current, in the epileptic Scn2aQ54 mouse model. We also examined the effect of GS967 in the maximal electroshock model and evaluated effects of the compound on neuronal excitability, propensity for hilar neuron loss, development of mossy fiber sprouting and survival of Scn2aQ54 mice. Results We found that ranolazine was capable of reducing seizure frequency by ~50% in Scn2aQ54 mice. The more potent persistent current blocker GS967 reduced seizure frequency by greater than 90% in Scn2aQ54 mice and protected against induced seizures in the maximal electroshock model. GS967 greatly attenuated abnormal spontaneous action potential firing in pyramidal neurons acutely isolated from Scn2aQ54 mice. In addition to seizure suppression in vivo, GS967 treatment greatly improved the survival of Scn2aQ54 mice, prevented hilar neuron loss, and suppressed the development of hippocampal mossy fiber sprouting. Significance Our findings indicate that the selective persistent sodium current blocker GS967 has potent antiepileptic activity and this compound could inform development of new agents. PMID:24862204

  9. 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.

  10. 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.

  11. 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

  12. Voltage-activated currents in somatic muscle of the nematode parasite Ascaris suum.

    PubMed

    Martin, R J; Thorn, P; Gration, K A; Harrow, I D

    1992-12-01

    1. Voltage-activated currents in cell bodies of the somatic muscle cells of Ascaris suum were studied using a two-microelectrode voltage-clamp technique. Cells recorded from had resting membrane potentials around -35 mV and had input conductances in the range 1-10 microS. 2. In cells bathed in artificial perienteric fluid, depolarizing steps from a holding potential of -35 mV elicited outward currents at a threshold of -15 mV. These currents had inwardly directed inflections on the rising phase, suggesting the presence of more than one current. Hyperpolarizing steps did not activate current. 3. Tetraethylammonium (TEA+, 69 mmol l-1) blocked the outward currents and allowed a voltage-dependent inactivating Ca2+ current to be observed. The peak current-voltage relationship was U-shaped with a threshold around -15 mV and peak at +5 mV. The reversal potential of the Ca2+ current was estimated by extrapolation to be +45 mV. 4. The permeability of the voltage-activated outward currents was studied by examining reversal potentials of tail currents. The reversal potentials were linearly dependent on the logarithm of the extracellular potassium concentration if extracellular [K+] was greater than 10 mmol l-1. The Na+/K+ permeability ratio of the currents was 0.04. 5. Inactivation, seen as a decline following the peak of the K+ current, was produced by maintained depolarization. The recovery from inactivation was complex and could be described by the sum of two exponentials with time constants of 0.67 s and 20.1 s. Steady-state inactivation of the K+ currents was observed at a range of holding potentials. Only a proportion (34%) of the total K+ current was inactivated by holding potentials more positive than -20 mV. 6. Extracellular application of 5 mmol l-1 4-aminopyridine (4-AP) selectively abolished an early fast component of the K+ current (the peak). The 4-AP-sensitive current decayed quickly with a time constant of around 10 ms; a Boltzmann fit to its activation curve

  13. Hysteresis Control for Current Harmonics Suppression Using Shunt Active Filter

    NASA Astrophysics Data System (ADS)

    Ahuja, Rajesh Kr; Chauhan, Aasha; Sharma, Sachin

    2012-11-01

    Recently wide spread of power electronic equipment has caused an increase of the harmonic disturbances in the power systems. The nonlinear loads draw harmonic and reactive power components of current from ac mains. Current harmonics generated by nonlinear loads such as adjustable speed drives,static powersupplies and UPS. Thus a perfect compensator is required to avoid the consequences due to harmonics. To overcome problems due to harmonics, Shunt Active Power Filter (SAPF) has been considered extensively. SAPF has better harmonic compensation than the other approaches used for solving the harmonic related problems. The performance of the SAPF depends upon different control strategies. This paper presents the performance analysis of SAPF under most important control strategy namely instantaneous real active and reactive power method (p-q) for extracting reference currents of shunt active filters under unbalanced load condition. Detailed simulations have been carried out considering this control strategy and adequate results were presented. In this paper, harmonic control strategy is applied to compensate the current harmonics in the system. A detailed study about the harmonic control method has been used using shunt active filter technique.

  14. 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

  15. 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

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

    PubMed

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

    2012-12-01

    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.

  17. 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

  18. Current research and case work activities of criminalistics in Japan.

    PubMed

    Seta, S

    1996-06-28

    The current research and case work activities of criminalistics in Japan are described. The selected forensic science disciplines are forensic osteology including specialized technology of skull identification, forensic serology, forensic DNA analysis of poisonous materials, forensic hair and fiber analysis, trace evidence analysis, document analysis, forensic psychology mainly concerned with the so-called lie-detector, forensic image analysis, voice print analysis, fire and explosion analysis, forensic engineering, firearm and toolmark analysis. The current activity of the Training Institute of Forensic Science at the National Research Institute of Police Science is also briefly described with special regard to the education and training course of forensic DNA typing analysis. Instruments for analytical and methodological use are listed according to the availability in evidence sample analyses.

  19. 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

  20. 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.

  1. Parallel input parallel output high voltage bi-directional converters for driving dielectric electro active polymer actuators

    NASA Astrophysics Data System (ADS)

    Thummala, P.; Zhang, Z.; Andersen, M. A. E.; Rahimullah, S.

    2014-03-01

    Dielectric electroactive polymer (DEAP) actuators are capacitive devices which provide mechanical motions when charged electrically. The charging characteristics of a DEAP actuator depends on its size, voltage applied to its electrodes, and its operating frequency. The main idea of this paper is to design and implement driving circuits for the DEAP actuators for their use in various applications. This paper presents implementation of parallel input, parallel output, high voltage (~2.5 kV) bi-directional DC-DC converters for driving the DEAP actuators. The topology is a bidirectional flyback DC-DC converter incorporating commercially available high voltage MOSFETs (4 kV) and high voltage diodes (5 kV). Although the average current of the aforementioned devices is limited to 300 mA and 150 mA, respectively, connecting the outputs of multiple converters in parallel can provide a scalable design. This enables operating the DEAP actuators in various static and dynamic applications e.g. positioning, vibration generation or damping, and pumps. The proposed idea is experimentally verified by connecting three high voltage converters in parallel to operate a single DEAP actuator. The experimental results with both film capacitive load and the DEAP actuator are shown for a maximum charging voltage of 2 kV.

  2. Detecting Current Geological Activity on the Galilean Satellites

    NASA Astrophysics Data System (ADS)

    Phillips, C. B.; Chyba, C. F.

    2003-12-01

    The Galilean satellites have provided varying evidence for current, or recent, geological activity. Surface change on volcanic Io is frequent and widespread, while Europa's young surface and potential subsurface ocean layer indicate recent activity which could extend to the present day. Ganymede and Callisto have more ancient surfaces, but the detection of possible ocean layers beneath their icy surfaces suggests that ongoing geological activity cannot be ruled out. A number of methods are available to search for and characterize current geological activity, and such observations should be carried out by any upcoming mission to the Jovian system such as JIMO. 1) Change detection: Comparisons of images of the same portion of the surfaces of the satellites, taken on subsequent orbits or missions, can be used to search for differences due to geological activity (Phillips et al. 2000 JGR 105, 22579). Effective comparisons require filters at comparable wavelengths and bandpasses to Galileo (and perhaps Voyager), and images of regions observed by Galileo taken at the same phase angle, wavelength, and resolution. Such observations can monitor ongoing volcanic activity on Io, even from distant imaging taken while orbiting other satellites. These images should be optimized at Europa, but it is worth studying images of Ganymede and Callisto as well, especially at higher resolutions, to see if any changes have taken place since Galileo or Voyager. 2) Plume searches: High-resolution imaging sequences at locations where periodic stresses favor plume activity, as well as global-scale images including the limb of the planet, can be used to search for plume activity on Europa. Regular plume monitoring can also be used to observe volcanic activity on Io. An orbiting spectrometer could look for particular outgassed constituents from the satellites, and monitoring of the space environment surrounding Europa by charged particle detectors on a future mission could allow detection of

  3. Characterization of hyperpolarization-activated currents in deep dorsal horn neurons of neonate mouse spinal cord in vitro.

    PubMed

    Rivera-Arconada, Ivan; Roza, Carolina; Lopez-Garcia, Jose Antonio

    2013-07-01

    Emerging evidence suggests that blockade of hyperpolarization-activated current (Ih) produces analgesia acting at peripheral sites. However, little is known about the role of this current in central pain-processing structures. The aim of the present work was to characterize the Ih in deep dorsal horn neurons and to assess the role of the current in the transmission of somatosensory signals across spinal circuits. To these purpose in vitro preparations of the spinal cord from mice pups were used in combination with whole cell recordings to characterize the current in native neurons. Extracellular recordings from sensory and motor pathways were performed to assess the role of the current in spinal somatosensory processing. Cesium chloride and ZD7288 were used as current blockers. Most deep dorsal horn neurons showed a functional Ih that was blocked by ZD7288 and cesium. Ih blockade caused hyperpolarization, increased input resistance and potentiation of synaptic responses. Excitatory effects of Ih blockade on synaptic transmission were confirmed in projecting anterolateral axons and ventral roots. Ih modulation by cAMP produced a rightward shift in the voltage dependency curve and blocked excitatory effects of ZD7288 on sensory pathways. Results indicate that Ih currents play a stabilizing role in the spinal cord controlling transmission across sensory and motor spinal pathways via cellular effects on input resistance and excitability. In addition, results suggest that current modulation may alter significantly the role of the current in somatosensory processing. PMID:23376246

  4. 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

  5. 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

  6. Design of robust H ∞ controller for a half-vehicle active suspension system with input delay

    NASA Astrophysics Data System (ADS)

    Li, Hongyi; Liu, Honghai; Hand, Steve; Hilton, Chris

    2013-04-01

    This article is concerned with the problem of robust H ∞ control for a half-vehicle active suspension system with input delay. The delay is assumed to be interval time-varying delay with unknown derivative. The vehicle front sprung mass and the rear unsprung mass are assumed to be varying due to vehicle load variation and may result in parameter uncertainties being modelled by polytopic uncertainty. First of all, regarding the heave and pitch accelerations as the optimisation objectives, and suspension deflection and relative tire load constraints as the output constraints, we build the corresponding suspension systems. Then, by constructing a novel Lyapunov functional involved with the lower and upper bounds of the delay, sufficient condition for the existence of robust H ∞ controller is given to ensure robust asymptotical stability of the closed-loop system and also guarantee the constrained performance. The condition can be converted into convex optimisation problem and verified easily by means of standard software. Finally, a design example is exploited to demonstrate the effectiveness of the proposed design method.

  7. Two kinetically distinct components of hyperpolarization-activated current in rat superior colliculus-projecting neurons.

    PubMed Central

    Solomon, J S; Nerbonne, J M

    1993-01-01

    suggest that Ih,f and Ih,s reflect the presence of two functionally distinct channel populations. 7. No decrements in time-dependent hyperpolarization-activated inward currents were observed during hyperpolarizations lasting up to 18 s, suggesting that neither Ih,f nor Ih,s inactivates from the open state. In addition, 10 s depolarizations to 0 mV prior to activation did not alter the waveforms of the inward currents activated directly from -40 mV, suggesting that Ih,f and Ih,s also do not inactivate from closed states. 8. The hyperpolarization-activated currents in rat SCP neurons are ideally suited to contribute to the control of the resting membrane potential and input resistance.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7505823

  8. Current activated tip sintering of Ni-Ti intermetallics

    NASA Astrophysics Data System (ADS)

    Sharma, Nitin

    This thesis investigated the current activated tip-sintering of reactive mixtures of nickel and titanium to form Ni-Ti intermetallics. The effect of elemental powder composition, heating profile and micro-jet inert gas pressures on the developed macro- and microstructure was investigated. The heating profile brought upon by selective electric current application was found to have a significant effect on whether the reaction is a volumetric combustion or a self-propagating high temperature one. The best results in terms of homogeneity and Ni-Ti intermetallics yield, were obtained for an inert gas pressure of 4 psi under for the nickel rich composition. In addition, surprising results at the higher inert gas pressures show the formation of hollow products, which can give rise future exploration of this technique for combustion synthesizing hollow products of different shapes.

  9. 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)

  10. 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

  11. 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

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

    PubMed

    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

  13. New semi-active damping concept using eddy currents

    NASA Astrophysics Data System (ADS)

    Sodano, Henry A.; Inman, Daniel J.; Belvin, W. K.

    2005-05-01

    A damping effect can be induced on a conductive structure that is vibrating in a magnetic field. This damping effect is caused by the eddy currents that are induced in the material due to a time varying magnetic field. The density of these currents is directly related to the velocity of the conductor in the magnetic field. However, once the currents are formed the internal resistance of the conductive material causes them to dissipate into heat, resulting in a removal of energy from the system and a damping effect. In a previous study, a permanent magnetic was fixed in a location such that the poling axis was perpendicular to the beam's motion and the radial magnetic flux was used to passively suppress the beam"s vibration. Using this passive damping concept and the idea that the damping force is directly related to the velocity of the conductor, a new semi-active damping mechanism will be created. This new damper will function by allowing the position of the magnet to change relative to the beam and thus allowing the net velocity between the two to be maximized and the damping force significantly increased. Using this concept, a model of both the passive and active portion of the system will be developed, allowing the beams response to be simulated. To verify the accuracy of this model, experiments will be performed that demonstrate both the accuracy of the model and the effectiveness of this semi-active control system for use in suppressing the transverse vibration of a structure.

  14. Segmental organization of vestibulospinal inputs to spinal interneurons mediating crossed activation of thoracolumbar motoneurons in the neonatal mouse.

    PubMed

    Kasumacic, Nedim; Lambert, François M; Coulon, Patrice; Bras, Helene; Vinay, Laurent; Perreault, Marie-Claude; Glover, Joel C

    2015-05-27

    Vestibulospinal pathways activate contralateral motoneurons (MNs) in the thoracolumbar spinal cord of the neonatal mouse exclusively via axons descending ipsilaterally from the vestibular nuclei via the lateral vestibulospinal tract (LVST; Kasumacic et al., 2010). Here we investigate how transmission from the LVST to contralateral MNs is mediated by descending commissural interneurons (dCINs) in different spinal segments. We test the polysynaptic nature of this crossed projection by assessing LVST-mediated ventral root (VR) response latencies, manipulating synaptic responses pharmacologically, and tracing the pathway transynaptically from hindlimb extensor muscles using rabies virus (RV). Longer response latencies in contralateral than ipsilateral VRs, near-complete abolition of LVST-mediated calcium responses in contralateral MNs by mephenesin, and the absence of transsynaptic RV labeling of contralateral LVST neurons within a monosynaptic time window all indicate an overwhelmingly polysynaptic pathway from the LVST to contralateral MNs. Optical recording of synaptically mediated calcium responses identifies LVST-responsive ipsilateral dCINs that exhibit segmental differences in proportion and dorsoventral distribution. In contrast to thoracic and lower lumbar segments, in which most dCINs are LVST responsive, upper lumbar segments stand out because they contain a much smaller and more ventrally restricted subpopulation of LVST-responsive dCINs. A large proportion of these upper lumbar LVST-responsive dCINs project to contralateral L5, which contains many of the hindlimb extensor MNs activated by the LVST. A selective channeling of LVST inputs through segmentally and dorsoventrally restricted subsets of dCINs provides a mechanism for targeting vestibulospinal signals differentially to contralateral trunk and hindlimb MNs in the mammalian spinal cord.

  15. 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.

  16. Aspects of calcium-activated chloride currents: a neuronal perspective.

    PubMed

    Scott, R H; Sutton, K G; Griffin, A; Stapleton, S R; Currie, K P

    1995-06-01

    Ca(2+)-activated Cl- channels are expressed in a variety of cell types, including central and peripheral neurones. These channels are activated by a rise in intracellular Ca2+ close to the cell membrane. This can be evoked by cellular events such as Ca2+ entry through voltage- and ligandgated channels or release of Ca2+ from intracellular stores. Additionally, these Ca(2+)-activated Cl currents (ICl(Ca)) can be activated by raising intracellular Ca2+ through artificial experimental procedures such as intracellular photorelease of Ca2+ from "caged" photolabile compounds (e.g. DM-nitrophen) or by treating cells with Ca2+ ionophores. The potential changes that result from activation of Ca(2+)-activated Cl- channels are dependent on resting membrane potential and the equilibrium potential for Cl-. Ca2+ entry during a single action potential is sufficient to produce substantial after potentials, suggesting that the activity of these Cl- channels can have profound effects on cell excitability. The whole cell ICl(Ca) can be identified by sensitivity to increased Ca2+ buffering capacity of the cell, anion substitution studies and reversal potential measurements, as well as by the actions of Cl- channel blockers. In cultured sensory neurones, there is evidence that the ICl(Ca) deactivates as Ca2+ is buffered or removed from the intracellular environment. To date, there is no evidence in mammalian neurones to suggest these Ca(2+)-sensitive Cl- channels undergo a process of inactivation. Therefore, ICl(Ca) can be used as a physiological index of intracellular Ca2+ close to the cell membrane. The ICl(Ca) has been shown to be activated or prolonged as a result of metabolic stress, as well as by drugs that disturb intracellular Ca2+ homeostatic mechanisms or release Ca2+ from intracellular stores. In addition to sensitivity to classic Cl- channel blockers such as niflumic acid, derivatives of stilbene (4,4'diisothiocyanostilbene-2,2'-disulphonic acid, 4-acetamido-4

  17. Early sensory cortex is activated in the absence of explicit input during crossmodal item retrieval: evidence from MEG.

    PubMed

    Pillai, Ajay S; Gilbert, Jessica R; Horwitz, Barry

    2013-02-01

    Crossmodal associations form a fundamental aspect of our daily lives. In this study we investigated the neural correlates of crossmodal association in early sensory cortices using magnetoencephalography (MEG). We used a paired associate recognition paradigm in which subjects were tested after multiple training sessions over a span of four weeks. Subjects had to learn 12 abstract, nonlinguistic, pairs of auditory and visual objects that consisted of crossmodal (visual-auditory, VA; auditory-visual, AV) and unimodal (visual-visual, VV; auditory-auditory, AA) paired items. Visual objects included abstract, non-nameable, fractal-like images, and auditory objects included abstract tone sequences. During scanning, subjects were shown the first item of a pair (S1), followed by a delay, then the simultaneous presentation of a visual and auditory stimulus (S2). Subjects were instructed to indicate whether either of the S2 stimuli contained the correct paired associate of S1. Synthetic aperture magnetometry (SAMspm), a minimum variance beamformer, was then used to assess source power differences between the crossmodal conditions and their corresponding unimodal conditions (i.e., AV-AA and VA-VV) in the beta (15-30 Hz) and low gamma frequencies (31-54 Hz) during the S1 period. We found greater power during S1 in the corresponding modality-specific association areas for crossmodal compared with unimodal stimuli. Thus, even in the absence of explicit sensory input, the retrieval of well-learned, crossmodal pairs activate sensory areas associated with the corresponding modality. These findings support theories which posit that modality-specific regions of cortex are involved in the storage and retrieval of sensory-specific items from long-term memory.

  18. Active debris removal: Recent progress and current trends

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    According to all available findings at international level, the Kessler syndrome, increase of the number of space debris in Low Earth Orbits due to mutual collisions, appears now to be a fact, triggered mainly by several major break-ups in orbit which occurred since 2007. The time may have come to study how to clean this fundamentally useful orbital region in an active way. CNES has studied potential solutions for more than 12 years! The paper aims at reviewing the current status of these activities. The high level requirements are fundamental, and have to be properly justified. The working basis, as confirmed through IADC studies consists in the removal of 5-10 integer objects from the overcrowded orbits, spent upper stages or old satellites, as identified by NASA. The logic of CNES activities consider a stepped approach aiming at progressively gaining the required Technological Readiness Level on the features required for Active Debris Removal which have not yet been demonstrated in orbit. The rendezvous with a non-cooperative, un-prepared, tumbling debris is essential. Following maturation gained with Research and Technology programs, a set of small orbital demonstrators could enable a confidence high enough to perform a full end to end demonstration performing the de-orbiting of a large debris and paving the way for the development of a first generation operational de-orbiter. The internal CNES studies, led together by the Toulouse Space Centre and the Paris Launcher Directorate, have started in 2008 and led to a detailed System Requirements Document used for the Industrial studies. Three industrial teams did work under CNES contract during 2011, led by Thales Alenia Space, Bertin Technologies and Astrium Space Transportation, with numerous sub-contractors. Their approaches were very rich, complementary, and innovative. The second phase of studies began mid-2012. Some key questions nevertheless have to be resolved, and correspond generally to current IADC

  19. 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.

  20. 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.

  1. 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.

  2. The Evolution of the Net Twist Current and the Net Shear Current in Active Region NOAA 10930

    NASA Astrophysics Data System (ADS)

    Suthar, Yogita; Venkatakrishnan, P.; Ravindra, B.; Jaaffrey, S. N. A.

    2014-07-01

    The electric current exists because of the non-potential magnetic field in solar active regions. We present the evolution of net current in the solar active region NOAA 10930 as the sum of shear current and twist current by using 27 high-resolution vector magnetograms obtained with Hinode/SOT-SP during 9 - 15 December 2006. This active region was highly eruptive and produced a large number of flares ranging from B to X class. We derived local distribution of shear and twist current densities in this active region and studied the evolution of net shear current (NSC) and net twist current (NTC) in the N-polarity and S-polarity regions separately. We found the following: i) The twist current density was dominant in the umbrae. ii) The footpoint of the emerging flux rope showed a dominant twist current. iii) The shear current density and twist current density appeared in alternate bands around the umbrae. iv) On the scale of the active region, NTC was always larger than NSC. v) Both NTC and NSC decreased after the onset of an X3.4 class flare that occurred on 13 December 2006.

  3. 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.

  4. 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

  5. Terrestrial Reference Systems and Frames. A review of current activities

    NASA Astrophysics Data System (ADS)

    Boucher, C. C.

    2009-12-01

    Terrestrial Reference Systems (TRS) refer to an important domain of Geodesy, involving both theoretical and applied aspects, as well as deep connections with Astronomy, Earth Sciences and Geo-information. The concept of TRS implies several visions : - An astronomical vision, using TRS to study translational and rotational motion of the Earth in inertial space - An Earth Science vision, using TRS to build physical models of the Earth system, and its various components (solid earth, oceans, atmosphere, hydrosphere) - A metrological vision, using TRS together with suitable coordinate systems (geographical coordinates, map projections…) to define geographical position of objects in the Earth’s vicinity A survey of current activities in this area is presented, referring to works done by the International Association of Geodesy (IAG) and more specifically its Commission 1, GGOS and IERS. A focus is done on concepts and terminology, as well as progresses to get a wide acceptance on the International Terrestrial Reference System (ITRS) and its system of realizations through global, regional and national frames, as well as through specific systems such as satellite navigation systems.

  6. 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

  7. 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

  8. An equivalent current source model and laplacian weighted minimum norm current estimates of brain electrical activity.

    PubMed

    He, Bin; Yao, D; Lian, Jie; Wu, D

    2002-04-01

    We have developed a method for estimating the three-dimensional distribution of equivalent current sources inside the brain from scalp potentials. Laplacian weighted minimum norm algorithm has been used in the present study to estimate the inverse solutions. A three-concentric-sphere inhomogeneous head model was used to represent the head volume conductor. A closed-form solution of the electrical potential over the scalp and inside the brain due to a point current source was developed for the three-concentric-sphere inhomogeneous head model. Computer simulation studies were conducted to validate the proposed equivalent current source imaging. Assuming source configurations as either multiple dipoles or point current sources/sinks, in computer simulations we used our method to reconstruct these sources, and compared with the equivalent dipole source imaging. Human experimental studies were also conducted and the equivalent current source imaging was performed on the visual evoked potential data. These results highlight the advantages of the equivalent current source imaging and suggest that it may become an alternative approach to imaging spatially distributed current sources-sinks in the brain and other organ systems.

  9. Activation of Ih and TTX-sensitive sodium current at subthreshold voltages during CA1 pyramidal neuron firing.

    PubMed

    Yamada-Hanff, Jason; Bean, Bruce P

    2015-10-01

    We used dynamic clamp and action potential clamp techniques to explore how currents carried by tetrodotoxin-sensitive sodium channels and HCN channels (Ih) regulate the behavior of CA1 pyramidal neurons at resting and subthreshold voltages. Recording from rat CA1 pyramidal neurons in hippocampal slices, we found that the apparent input resistance and membrane time constant were strongly affected by both conductances, with Ih acting to decrease apparent input resistance and time constant and sodium current acting to increase both. We found that both Ih and sodium current were active during subthreshold summation of artificial excitatory postsynaptic potentials (EPSPs) generated by dynamic clamp, with Ih dominating at less depolarized voltages and sodium current at more depolarized voltages. Subthreshold sodium current-which amplifies EPSPs-was most effectively recruited by rapid voltage changes, while Ih-which blunts EPSPs-was maximal for slow voltage changes. The combined effect is to selectively amplify rapid EPSPs. We did similar experiments in mouse CA1 pyramidal neurons, doing voltage-clamp experiments using experimental records of action potential firing of CA1 neurons previously recorded in awake, behaving animals as command voltages to quantify flow of Ih and sodium current at subthreshold voltages. Subthreshold sodium current was larger and subthreshold Ih was smaller in mouse neurons than in rat neurons. Overall, the results show opposing effects of subthreshold sodium current and Ih in regulating subthreshold behavior of CA1 neurons, with subthreshold sodium current prominent in both rat and mouse CA1 pyramidal neurons and additional regulation by Ih in rat neurons.

  10. 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

  11. Sensitivity of Self-Organizing Map surface current patterns to the use of radial vs. Cartesian input vectors measured by high-frequency radars

    NASA Astrophysics Data System (ADS)

    Kalinić, Hrvoje; Mihanović, Hrvoje; Cosoli, Simone; Vilibić, Ivica

    2015-11-01

    In this paper, the Self-Organizing Map (SOM) method was applied to the surface currents data obtained between February and November 2008 by a network of high-frequency (HF) radars in the northern Adriatic. The sensitivity of the derived SOM solutions was tested in respect to the change of coordinate system of the data introduced to the SOM. In one experiment the original radial data measurements were used, and in the other experiment the Cartesian (total) current vectors derived from original radar data were analyzed. Although the computation of SOM solutions was not a demanding task, comparing both neural lattices yielded the nondeterministic polynomial time (NP) problem for which is difficult to propose a solution that will be globally optimal. Thus, we suggested utilizing the greedy algorithm with underlying assumption of 1-to-1 mapping between lattices. The results suggested that such solution could be local, but not global optimum and that the latter assumption could lower the obtained correlations between the patterns. However, without the assumption of 1-to-1 mapping between lattices, correlation between the derived SOM patterns was quite high, indicating that SOM mapping introduced to the radial current vectors and subsequent transformation into Cartesian coordinate system does not significantly affect obtained patterns in comparison to the SOM mapping done on the derived Cartesian current vectors. The documented similarity corroborates the use of total current vectors in various oceanographic studies, as being representative derivative of original radial measurements.

  12. 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.

  13. 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.

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

    PubMed

    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.

  15. 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…

  16. 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.

  17. 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…

  18. 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…

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. 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

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

    PubMed Central

    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 Ca2+-independent but frequency- and voltage-dependent manner. Experimental evidence and computer simulations demonstrate 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 Ca2+ 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

  5. 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.

  6. Space Station - An overview of current U.S. activities

    NASA Technical Reports Server (NTRS)

    Freitag, R. F.

    1984-01-01

    The National Aeronautics and Space Administration (NASA) has begun developing a permanently manned Space Station as mandated by President Reagan. The Space Station will be operational within a decade and is the 'Next Logical Step' in America's space program. This paper presents a summary of the Space Station status, current planning guidelines, and the possibilities for international participation in the program. The conceptual architecture and evolutionary development options for the Space Station are also briefly discussed.

  7. 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)

  8. 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)

  9. 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.…

  10. 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...

  11. 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

  12. Calcium-activated conductance in skate electroreceptors: current clamp experiments

    PubMed Central

    1977-01-01

    When current clamped, skate electroreceptor epithelium produces large action potentials in response to stimuli that depolarize the lumenal faces of the receptor cells. With increasing stimulus strength these action potentials become prolonged. When the peak voltage exceeds about 140 mV the repolarizing phase is blocked until the end of the stimulus. Perfusion experiments show that the rising phase of the action potential results from an increase in calcium permeability in the lumenal membranes. Perfusion of the lumen with cobalt or with a zero calcium solution containing EGTA blocks the action potential. Perfusion of the lumen with a solution containing 10 mM Ca and 20 mM EGTA initially slows the repolarizing process at all voltages and lowers the potential at which it is blocked. With prolonged perfusion, repolarization is blocked at all voltages. When excitability is abolished by perfusion with cobalt, or with a zero calcium solution containing EGTA, no delayed rectification occurs. We suggest that repolarization during the action potential depends on an influx of calcium into the cytoplasm, and that the rate of repolarization depends on the magnitude of the inward calcium current. Increasingly large stimuli reduce the rate of repolarization by reducing the driving force for calcium, and then block repolarization by causing the lumenal membrane potential to exceed ECa. Changes in extracellular calcium affect repolarization in a manner consistent with the resulting change in ECa. PMID:190338

  13. 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.

  14. 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.

  15. [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

  16. 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

  17. Proton currents constrain structural models of voltage sensor activation

    PubMed Central

    Randolph, Aaron L; Mokrab, Younes; Bennett, Ashley L; Sansom, Mark SP; Ramsey, Ian Scott

    2016-01-01

    The Hv1 proton channel is evidently unique among voltage sensor domain proteins in mediating an intrinsic ‘aqueous’ H+ conductance (GAQ). Mutation of a highly conserved ‘gating charge’ residue in the S4 helix (R1H) confers a resting-state H+ ‘shuttle’ conductance (GSH) in VGCs and Ci VSP, and we now report that R1H is sufficient to reconstitute GSH in Hv1 without abrogating GAQ. Second-site mutations in S3 (D185A/H) and S4 (N4R) experimentally separate GSH and GAQ gating, which report thermodynamically distinct initial and final steps, respectively, in the Hv1 activation pathway. The effects of Hv1 mutations on GSH and GAQ are used to constrain the positions of key side chains in resting- and activated-state VS model structures, providing new insights into the structural basis of VS activation and H+ transfer mechanisms in Hv1. DOI: http://dx.doi.org/10.7554/eLife.18017.001 PMID:27572256

  18. 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.

  19. 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.

  20. Index of current water-resources activities in Ohio, 1985

    USGS Publications Warehouse

    Eberle, Michael

    1985-01-01

    This report summarizes the U. S. Geological Survey 's Water Resources Division 's program in Ohio in 1985. The work of the Ohio District is carried out through the District office in Columbus and a field office in New Philadelphia. Collection of basic data needed for continuing determination and evaluation of the quantity, quality, and use of Ohio 's water resources is the responsibility of the District 's Hydrologic Surveillance Section. The Hydrologic Investigations Section conducts analytical and interpretive water-resource appraisals describing the occurrence, availability, and the physical, chemical, and biological characteristics of surface and groundwater. In addition to introductory material describing the structure of the Ohio District, information is presented on current projects, sites at which basic surface- and groundwater data are collected , and reports of Ohio 's water resources published by the U.S. Geological Survey and cooperating agencies. (USGS)

  1. Signaling inputs to invadopodia and podosomes

    PubMed Central

    Hoshino, Daisuke; Branch, Kevin M.; Weaver, Alissa M.

    2013-01-01

    Summary Remodeling of extracellular matrix (ECM) is a fundamental cell property that allows cells to alter their microenvironment and move through tissues. Invadopodia and podosomes are subcellular actin-rich structures that are specialized for matrix degradation and are formed by cancer and normal cells, respectively. Although initial studies focused on defining the core machinery of these two structures, recent studies have identified inputs from both growth factor and adhesion signaling as crucial for invasive activity. This Commentary will outline the current knowledge on the upstream signaling inputs to invadopodia and podosomes and their role in governing distinct stages of these invasive structures. We discuss invadopodia and podosomes as adhesion structures and highlight new data showing that invadopodia-associated adhesion rings promote the maturation of already-formed invadopodia. We present a model in which growth factor stimulation leads to phosphoinositide 3-kinase (PI3K) activity and formation of invadopodia, whereas adhesion signaling promotes exocytosis of proteinases at invadopodia. PMID:23843616

  2. Introduction of Current JAXA Test Standard and Recent Updating Activities

    NASA Astrophysics Data System (ADS)

    Shi, Qinzhong; Uchikawa, Hideaki; Yanagase, Kenchi

    2012-07-01

    JAXA has been promoting to build up background knowledge of testing in these recent 5 years under the promotion committee, consists of members of different space project managers, R&D research groups and spacecraft prime manufactures. Those outputs are documented each test handbooks. After the establishment of environmental test handbooks, JAXA has started from 2010 to reverse test standard, JERG-2- 002(General Engineering Requirement Guidance), which had been succeed from one of the three former originations, National Space Development Agency (NASDA). The major objectives of this first reverse from the old test standard are, 1) clarification of requirements from engineering guidance and explanation, 2) classifies the baseline requirements and tailoring guideline, 3) deletes the numbers of specific launchers and makes it more general, 4) compatibility with other JAXA design requirements. In this paper, the plan and structure of reversing test standard, the state of art of current reversed JAXA test standard, and discussion issues within the working group, the next future step for the next revision are introduced.

  3. Antibiofilm Activity of Electrical Current in a Catheter Model.

    PubMed

    Voegele, Paul; Badiola, Jon; Schmidt-Malan, Suzannah M; Karau, Melissa J; Greenwood-Quaintance, Kerryl E; Mandrekar, Jayawant N; Patel, Robin

    2016-03-01

    Catheter-associated infections are difficult to treat with available antimicrobial agents because of their biofilm etiology. We examined the effect of low-amperage direct electrical current (DC) exposure on established bacterial and fungal biofilms in a novel experimental in vitro catheter model. Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida parapsilosis biofilms were grown on the inside surfaces of polyvinyl chloride (PVC) catheters, after which 0, 100, 200, or 500 μA of DC was delivered via intraluminally placed platinum electrodes. Catheter biofilms and intraluminal fluid were quantitatively cultured after 24 h and 4 days of DC exposure. Time- and dose-dependent biofilm killing was observed with all amperages and durations of DC administration. Twenty-four hours of 500 μA of DC sterilized the intraluminal fluid for all bacterial species studied; no viable bacteria were detected after treatment of S. epidermidis and S. aureus biofilms with 500 μA of DC for 4 days. PMID:26711752

  4. Antibiofilm Activity of Electrical Current in a Catheter Model

    PubMed Central

    Voegele, Paul; Badiola, Jon; Schmidt-Malan, Suzannah M.; Karau, Melissa J.; Greenwood-Quaintance, Kerryl E.; Mandrekar, Jayawant N.

    2015-01-01

    Catheter-associated infections are difficult to treat with available antimicrobial agents because of their biofilm etiology. We examined the effect of low-amperage direct electrical current (DC) exposure on established bacterial and fungal biofilms in a novel experimental in vitro catheter model. Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida parapsilosis biofilms were grown on the inside surfaces of polyvinyl chloride (PVC) catheters, after which 0, 100, 200, or 500 μA of DC was delivered via intraluminally placed platinum electrodes. Catheter biofilms and intraluminal fluid were quantitatively cultured after 24 h and 4 days of DC exposure. Time- and dose-dependent biofilm killing was observed with all amperages and durations of DC administration. Twenty-four hours of 500 μA of DC sterilized the intraluminal fluid for all bacterial species studied; no viable bacteria were detected after treatment of S. epidermidis and S. aureus biofilms with 500 μA of DC for 4 days. PMID:26711752

  5. 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.

  6. [Current views of activating and regulatory mechanisms of blood coagulation].

    PubMed

    Osaki, Tsukasa; Ichinose, Akitada

    2014-07-01

    Coagulation factors play essential roles in not only hemostasis but also thrombosis. The coagulation reaction consists of a stepwise sequence of proteolytic reactions of the coagulation factors, and is generally divided into two pathways, a tissue factor(TF)-dependent "extrinsic pathway" and a contact factor-dependent "intrinsic pathway". The extrinsic pathway is responsible for the initiation of the clotting reaction, while the intrinsic pathway most likely amplifies it. Elevated levels of various coagulation factors such as TF, factor VIII and prothrombin have been linked to an increased thrombotic risk. To prevent thrombus formation, endothelial cells express several receptors and activators for anticoagulant factors such as antithrombin, TF-pathway inhibitor, protein C and protein S. Defects in this anticoagulant system also increase the risk of thrombosis.

  7. 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).

  8. 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

  9. 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…

  10. 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

  11. 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

  12. Cyclic-nucleotide–gated cation current and Ca2+-activated Cl current elicited by odorant in vertebrate olfactory receptor neurons

    PubMed Central

    Li, Rong-Chang; Ben-Chaim, Yair; Yau, King-Wai; Lin, Chih-Chun

    2016-01-01

    Olfactory transduction in vertebrate olfactory receptor neurons (ORNs) involves primarily a cAMP-signaling cascade that leads to the opening of cyclic-nucleotide–gated (CNG), nonselective cation channels. The consequent Ca2+ influx triggers adaptation but also signal amplification, the latter by opening a Ca2+-activated Cl channel (ANO2) to elicit, unusually, an inward Cl current. Hence the olfactory response has inward CNG and Cl components that are in rapid succession and not easily separable. We report here success in quantitatively separating these two currents with respect to amplitude and time course over a broad range of odorant strengths. Importantly, we found that the Cl current is the predominant component throughout the olfactory dose–response relation, down to the threshold of signaling to the brain. This observation is very surprising given a recent report by others that the olfactory-signal amplification effected by the Ca2+-activated Cl current does not influence the behavioral olfactory threshold in mice. PMID:27647918

  13. 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.

  14. WATERSHEED NUTRIENT INPUTS, PHYTOPLANKTON ACCUMULATION, AND C STOCKS IN CHESAPEAKE BAY

    EPA Science Inventory

    Inputs of N and P to Chesapeake Bay have been enhanced by anthropogenic activities. Fertilizers, developed areas, N emissions, and industrial effluents contribute to point and diffuse sources currently 2-20X higher than those from undisturbed watersheds. Enhanced nutrient inputs ...

  15. 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.

  16. 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

  17. 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.

  18. Input states for quantum gates

    SciTech Connect

    Gilchrist, A.; White, A.G.; Munro, W.J.

    2003-04-01

    We examine three possible implementations of nondeterministic linear optical controlled NOT gates with a view to an in-principle demonstration in the near future. To this end we consider demonstrating the gates using currently available sources, such as spontaneous parametric down conversion and coherent states, and current detectors only able to distinguish between zero and many photons. The demonstration is possible in the coincidence basis and the errors introduced by the nonoptimal input states and detectors are analyzed.

  19. 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

  20. 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.

  1. Principle 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

    Principle Component Analysis is performed on northern and southern hemisphere Birkeland or field-aligned current (FAC) measurements from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE). PCA identifies the patterns in the FACs that respond coherently to different aspects of geomagnetic activity. The region 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. Other interhemispheric differences are discussed.

  2. Activation kinetics of calcium currents in bull-frog sympathetic neurones.

    PubMed Central

    Sala, F

    1991-01-01

    1. Calcium currents were recorded in dissociated bull-frog sympathetic neurones (BSNs) through patch pipettes using discontinuous voltage clamp. Activation kinetics were examined by analysing turn-on and turn-off currents. 2. After short depolarizing pulses turn-off tail currents were fitted with the sum of two exponentials. The fast component (time constant, tau approximately 240 microseconds at -40 mV) was undoubtedly due to the closure of calcium channels. The significance of a small and slower component is discussed. 3. Neither activation nor deactivation time courses changed as channels inactivated during progressively longer pulses or when the holding potential was less negative. No specific component was selectively suppressed by these manipulations. 4. Steady-state activation of the Ca2+ current was described by the Boltzmann distribution raised to the second power. Currents had an apparent threshold at -30 mV and were half-activated at +5 mV. 5. Calcium current turned on following m2 kinetics throughout the range of activation. The slowest time constant was around 1.2 ms between 0 and +10 mV. Turn-on was faster at negative or more positive potentials. 6. The time course of decay of tail currents became progressively faster at more negative potentials. 7. The instantaneous current-voltages (I-V) curve was obtained from tail current measurements and fitted by a modified constant-field equation. 8. The measured peak I-V curve could be reconstructed from the activation curve and the instantaneous I-V curve. 9. The activation kinetics of the calcium current in BSNs were consistent with the existence of a single kinetic class of channels and can be described with a simple m2 Hodgkin-Huxley model. PMID:1653852

  3. Cutaneous inputs from the back abolish locomotor-like activity and reduce spastic-like activity in the adult cat following complete spinal cord injury

    PubMed Central

    Frigon, Alain; Thibaudier, Yann; Johnson, Michael D.; Heckman, C.J.; Hurteau, Marie-France

    2012-01-01

    Spasticity is a condition that can include increased muscle tone, clonus, spasms, and hyperreflexia. In this study, we report the effect of manually stimulating the dorsal lumbosacral skin on spontaneous locomotor-like activity and on a variety of reflex responses in 5 decerebrate chronic spinal cats treated with clonidine. Cats were spinalized 1 month before the terminal experiment. Stretch reflexes were evoked by stretching the left triceps surae muscles. Crossed reflexes were elicited by electrically stimulating the right tibial or superficial peroneal nerves. Windup of reflex responses was evoked by electrically stimulating the left tibial or superficial peroneal nerves. We found that pinching the skin of the back abolished spontaneous locomotor-like activity. We also found that back pinch abolished the rhythmic activity observed during reflex testing without eliminating the reflex responses. Some of the rhythmic episodes of activity observed during reflex testing were consistent with clonus with an oscillation frequency greater than 3 Hz. Pinching the skin of the back effectively abolished rhythmic activity occurring spontaneously or evoked during reflex testing, irrespective of oscillation frequency. The results are consistent with the hypothesis that locomotion and clonus are produced by common central pattern-generators. Stimulating the skin of the back could prove helpful in managing undesired rhythmic activity in spinal cord-injured humans. PMID:22487200

  4. 75 FR 61816 - Agency Information Collection Activities: Notice of Request for Extension of Currently Approved...

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    ... Information sections. The new data collection provides more detailed delinquent, charge off and recovery loan... ADMINISTRATION Agency Information Collection Activities: Submission to OMB for Revision to a Currently Approved Information Collection; Comment Request AGENCY: National Credit Union Administration (NCUA). ACTION:...

  16. 77 FR 5868 - Agency Information Collection Activities; Extension of a Currently Approved Information...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-06

    ... Federal Motor Carrier Safety Administration Agency Information Collection Activities; Extension of a Currently Approved Information Collection: Motor Carrier Identification Report AGENCY: Federal Motor Carrier... the Paperwork Reduction Act of 1995, FMCSA announces its plan to submit the Information...

  17. Large-conductance calcium-activated potassium current modulates excitability in isolated canine intracardiac neurons.

    PubMed

    Pérez, Guillermo J; Desai, Mayurika; Anderson, Seth; Scornik, Fabiana S

    2013-02-01

    We studied principal neurons from canine intracardiac (IC) ganglia to determine whether large-conductance calcium-activated potassium (BK) channels play a role in their excitability. We performed whole cell recordings in voltage- and current-clamp modes to measure ion currents and changes in membrane potential from isolated canine IC neurons. Whole cell currents from these neurons showed fast- and slow-activated outward components. Both current components decreased in the absence of calcium and following 1-2 mM tetraethylammonium (TEA) or paxilline. These results suggest that BK channels underlie these current components. Single-channel analysis showed that BK channels from IC neurons do not inactivate in a time-dependent manner, suggesting that the dynamic of the decay of the fast current component is akin to that of intracellular calcium. Immunohistochemical studies showed that BK channels and type 2 ryanodine receptors are coexpressed in IC principal neurons. We tested whether BK current activation in these neurons occurred via a calcium-induced calcium release mechanism. We found that the outward currents of these neurons were not affected by the calcium depletion of intracellular stores with 10 mM caffeine and 10 μM cyclopiazonic acid. Thus, in canine intracardiac neurons, BK currents are directly activated by calcium influx. Membrane potential changes elicited by long (400 ms) current injections showed a tonic firing response that was decreased by TEA or paxilline. These data strongly suggest that the BK current present in canine intracardiac neurons regulates action potential activity and could increase these neurons excitability.

  18. [Resource activation in clinical psychology and psychotherapy: review of theoretical issues and current research].

    PubMed

    Groß, L J; Stemmler, M; de Zwaan, M

    2012-08-01

    This review summarises theoretical issues and current research on working with clients' resources and strengths in clinical psychology and psychotherapy. Resource activation is considered as an important common factor in psychotherapy. In general, resource activation means an explicit focus on resources, strengths and potentials of the clients. After defining the term resources, considerations with regard to therapeutic attitude, principles of resource activation, approaches to resource diagnostics and different research strategies are presented. Current research focuses especially on the relation between resource activation and process variables in out-patient treatment.

  19. Effects of current physical activity on affective response to exercise: physical and social-cognitive mechanisms.

    PubMed

    Magnan, Renee E; Kwan, Bethany M; Bryan, Angela D

    2013-01-01

    Affective responses during exercise are often important determinants of exercise initiation and maintenance. Current physical activity may be one individual difference that is associated with the degree to which individuals have positive (or negative) affective experiences during exercise. The objective of this study was to explore physical and cognitive explanations of the relationship between current activity status (more versus less active) and affective response during a 30-minute bout of moderate-intensity exercise. Participants reported their current level of physical activity, exercise self-efficacy and affect during a 30-minute bout of moderate-intensity exercise. More active individuals experienced higher levels of positive affect and tranquillity and lower levels of negative affect and fatigue during exercise. Multivariate models for each affective state indicated separate processes through which physical activity may be associated with changes in affect during exercise. These models indicate that affect experienced during physical activity is related to the current activity level and these relationships can be partially explained by the physical and cognitive factors explored in this study. Recommendations for future research to elucidate whether positive affective response to physical activity improves as a function of becoming more active over time are discussed.

  20. Genetic activation of BK currents in vivo generates bidirectional effects on neuronal excitability.

    PubMed

    Montgomery, Jenna R; Meredith, Andrea L

    2012-11-13

    Large-conductance calcium-activated potassium channels (BK) are potent negative regulators of excitability in neurons and muscle, and increasing BK current is a novel therapeutic strategy for neuro- and cardioprotection, disorders of smooth muscle hyperactivity, and several psychiatric diseases. However, in some neurons, enhanced BK current is linked with seizures and paradoxical increases in excitability, potentially complicating the clinical use of agonists. The mechanisms that switch BK influence from inhibitory to excitatory are not well defined. Here we investigate this dichotomy using a gain-of-function subunit (BK(R207Q)) to enhance BK currents. Heterologous expression of BK(R207Q) generated currents that activated at physiologically relevant voltages in lower intracellular Ca(2+), activated faster, and deactivated slower than wild-type currents. We then used BK(R207Q) expression to broadly augment endogenous BK currents in vivo, generating a transgenic mouse from a circadian clock-controlled Period1 gene fragment (Tg-BK(R207Q)). The specific impact on excitability was assessed in neurons of the suprachiasmatic nucleus (SCN) in the hypothalamus, a cell type where BK currents regulate spontaneous firing under distinct day and night conditions that are defined by different complements of ionic currents. In the SCN, Tg-BK(R207Q) expression converted the endogenous BK current to fast-activating, while maintaining similar current-voltage properties between day and night. Alteration of BK currents in Tg-BK(R207Q) SCN neurons increased firing at night but decreased firing during the day, demonstrating that BK currents generate bidirectional effects on neuronal firing under distinct conditions.

  1. 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.

  2. 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

  3. The Evolution of the Electric Current during the Formation and Eruption of Active-region Filaments

    NASA Astrophysics Data System (ADS)

    Wang, Jincheng; Yan, Xiaoli; Qu, Zhongquan; Xue, Zhike; Xiang, Yongyuan; Li, Hao

    2016-02-01

    We present a comprehensive study of the electric current related to the formation and eruption of active region filaments in NOAA AR 11884. The vertical current on the solar surface was investigated by using vector magnetograms (VMs) observed by HMI on board the Solar Dynamics Observatory. To obtain the electric current along the filament's axis, we reconstructed the magnetic fields above the photosphere by using nonlinear force-free field extrapolation based on photospheric VMs. Spatio-temporal evolutions of the vertical current on the photospheric surface and the horizontal current along the filament's axis were studied during the long-term evolution and eruption-related period, respectively. The results show that the vertical currents of the entire active region behaved with a decreasing trend and the magnetic fields also kept decreasing during the long-term evolution. For the eruption-related evolution, the mean transverse field strengths decreased before two eruptions and increased sharply after two eruptions in the vicinity of the polarity inversion lines underneath the filament. The related vertical current showed different behaviors in two of the eruptions. On the other hand, a very interesting feature was found: opposite horizontal currents with respect to the current of the filament's axis appeared and increased under the filament before the eruptions and disappeared after the eruptions. We suggest that these opposite currents were carried by the new flux emerging from the photosphere bottom and might be the trigger mechanism for these filament eruptions.

  4. Inhibition of volume-activated chloride currents in endothelial cells by chromones.

    PubMed Central

    Heinke, S.; Szücs, G.; Norris, A.; Droogmans, G.; Nilius, B.

    1995-01-01

    1. We have studied the effects of the reported chloride channel blocker, sodium cromoglycate, on volume-activated Cl- currents in endothelial cells from bovine pulmonary artery by means of the whole-cell patch clamp technique. Cl- currents were activated by challenging the cells with a hypotonic extracellular solution of 60% of the normal osmolarity. 2. Half maximal activation of the current at +95 mV occurred after exposure of the cells for 148 +/- 10 s (n = 6) to hypotonic solution (HTS). At the same membrane potential but in the presence of 100 microM sodium cromoglycate (disodium-1,3-bis (2'-carboxylate-chromone-5'-yloxy)-2-hydroxy-propane) activation was delayed (253 +/- 25 s, n = 6) and the maximal current amplitude was reduced to 63 +/- 7% of the control (n = 13). 3. In comparison, an equimolar concentration of NPPB (5-nitro-2(3-phenyl) propylamino-benzoic acid), another Cl- channel blocker, completely blocked the volume-activated current in less than 20 s. 4. Sodium cromoglycate, applied at the time when the HTS-induced current was completely activated, dose-dependently inhibited this current with a concentration for half maximal inhibition of 310 +/- 70 microM. Data for nedocromil sodium were not significantly different from those for sodium cromoglycate. 5. Sodium cromoglycate, loaded into the endothelial cells via the patch pipette in ruptured patches, resulted in a decline of the HTS activated current with a time course that was compatible with diffusion of the compound from the pipette into the cell.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8564197

  5. 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

  6. Acetylcholine activates an inward current in single mammalian smooth muscle cells.

    PubMed

    Benham, C D; Bolton, T B; Lang, R J

    Acetylcholine, the major excitatory neurotransmitter to the smooth muscle of mammalian intestine, is known to depolarize smooth muscle cells with an apparent increase in membrane conductance. However, the ionic mechanisms that are triggered by muscarinic receptor activation and underlie this response are poorly understood, due in part to the technical problems associated with the electrophysiological study of smooth muscle. The muscarinic action of acetylcholine in certain neurones has been shown to involve the switching off of a resting K+ current (M-current) and a similar mechanism has recently also been identified in smooth muscle of amphibian stomach. We have now applied the patch-clamp technique to single smooth muscle cells of rabbit jejunum and find that muscarinic receptor activation switches on a nonselective, voltage-sensitive inward current. In addition, acetylcholine activates and then suppresses spontaneous K+ current transients, which are probably triggered by rises in intracellular Ca2+ in these cells.

  7. 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…

  8. 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,…

  9. 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…

  10. Calcium current activated by muscarinic receptors and thapsigargin in neuronal cells

    PubMed Central

    1994-01-01

    The activation of muscarinic receptors in N1E-115 neuroblastoma cells elicits a voltage-independent calcium current. The current turns on slowly, reaches its maximum value approximately 45 s after applying the agonist, is sustained as long as agonist is present, and recovers by one half in approximately 10 s after washing the agonist away. The current density is 0.11 +/- 0.08 pA/pF (mean +/- SD; n = 12). It is absent in zero-Ca++ saline and reduced by Mn++ and Ba++. The I(V) curve characterizing the current has an extrapolated reversal potential > +40 mV. The calcium current is observed in cells heavily loaded with BAPTA indicating that the calcium entry pathway is not directly gated by calcium. In fura-2 experiments, we find that muscarinic activation causes an elevation of intracellular Ca++ that is due to both intracellular calcium release and calcium influx. The component of the signal that requires external Ca++ has the same time course as the receptor operated calcium current. Calcium influx measured in this way elevates (Ca++)i by 89 +/- 41 nM (n = 7). Thapsigargin, an inhibitor of Ca++/ATPase associated with the endoplasmic reticulum (ER), activates a calcium current with similar properties. The current density is 0.22 +/- 0.20 pA/pF (n = 6). Thapsigargin activated current is reduced by Mn++ and Ba++ and increased by elevated external Ca++. Calcium influx activated by thapsigargin elevates (Ca++)i by 82 +/- 35 nM. The Ca++ currents due to agonist and due to thapsigargin do not sum, indicating that these procedures activate the same process. Carbachol and thapsigargin both cause calcium release from internal stores and the calcium current bears strong similarity to calcium-release-activated calcium currents in nonexcitable cells (Hoth, M., and R. Penner. 1993. Journal of Physiology. 465:359-386; Zweifach, A., and R. S. Lewis, 1993. Proceedings of the National Academy of Sciences, USA. 90:6295- 6299). PMID:7964592

  11. Expression of voltage-activated chloride currents in acute slices of human gliomas.

    PubMed

    Ullrich, N; Bordey, A; Gillespie, G Y; Sontheimer, H

    1998-04-01

    Using whole-cell patch-clamp recordings, we identified a novel voltage-activated chloride current that was selectively expressed in glioma cells from 23 patient biopsies. Chloride currents were identified in 64% of glioma cells studied in acute slices of nine patient biopsies. These derived from gliomas of various pathological grades. In addition, 98% of cells acutely isolated or in short-term culture from 23 patients diagnosed with gliomas showed chloride current expression. These currents, which we termed glioma chloride currents activated at potentials >45 mV, showed pronounced outward rectification, and were sensitive to bath application of the presumed Cl- channel specific peptide chlorotoxin (approximately 600 nM) derived from Leiurus scorpion venom. Interestingly, low grade tumours (e.g., pilocytic astrocytomas), containing more differentiated, astrocyte-like cells showed expression of glioma chloride currents in concert with voltage-activated sodium and potassium currents also seen in normal astrocytes. By contrast, high grade tumours (e.g., glioblastoma multiforme) expressed almost exclusively chloride currents, suggesting a gradual loss of Na+ currents and gain of Cl- currents with increasing pathological tumour grade. To expand on the observation that these chloride currents are glioma-specific, we introduced experimental tumours in scid mice by intracranial injection of D54MG glioma cells and subsequently recorded from tumour cells and adjacent normal glial cells in acute slices. We consistently observed expression of chlorotoxin-sensitive chloride channels in implanted glioma cells, but without evidence for expression of chloride channels in surrounding "normal" host glial cells, suggesting that these chloride channels are probably a glioma-specific feature. Finding of this novel glioma specific Cl- channel in gliomas in situ and it's selective binding of chlorotoxin may provide a way to identify or target glioma cells in the future.

  12. 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

  13. 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…

  14. 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.

  15. Evolution of Currents of Opposite Signs in the Flare-productive Solar Active Region NOAA 10930

    NASA Astrophysics Data System (ADS)

    Ravindra, B.; Venkatakrishnan, P.; Tiwari, Sanjiv Kumar; Bhattacharyya, R.

    2011-10-01

    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.

  16. 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.

  17. Characterization of the maitotoxin-activated cationic current from human skin fibroblasts

    PubMed Central

    Martínez-François, Juan Ramón; Morales-Tlalpan, Verónica; Vaca, Luis

    2002-01-01

    The maitotoxin (MTX)-induced cationic current (Imtx) from human skin fibroblasts was characterized using the patch-clamp technique in whole-cell configuration. Under resting conditions (absence of MTX), the main current observed is produced by an outwardly rectifying K+ channel which is inhibited by 1 mm TEA. The current reversal potential was −86 mV (n = 12). MTX (500 pm) activated a current with a linear current–voltage relationship and a reversal potential of −10 mV (n = 10). Replacing the extracellular Na+ and K+ with N-methyl-d-glucamine (NMDG) caused a shift of the reversal potential to a value below −100 mV, indicating that Na+ and K+, but not NMDG, carry Imtx. Further ion selectivity experiments showed that Ca2+ carries Imtx also. The resulting permeability sequence obtained with the Goldman–Hodgkin–Katz equation yielded Na+ (1) ≈ K+ (1) > Ca2+ (0.87). The Imtx activation time course reflected the changes in intracellular Ca2+ and Na+ measured with the fluorescent indicators fura-2 and SBFI, respectively, suggesting that the activation of Imtx brings about an increment in intracellular Ca2+ and Na+. Reducing the extracellular Ca2+ concentration below 1.8 mm prevented the activation of Imtx and the increment in intracellular Na+ induced by MTX. Mn2+ and Mg2+ could not replace Ca2+, but Ba2+ could replace Ca2+. MTX activation of current in 10 mm Ba2+ was approximately 50 % of that induced in the presence of 1.8 mm Ca2+. When 5 mm of the Ca2+ chelator BAPTA was included in the patch pipette, MTX either failed to activate the current or induced a small current (less than 15 % of the control), indicating that intracellular Ca2+ is also required for the activation of Imtx. Intracellular Ba2+ can replace Ca2+ as an activator of Imtx. However, in the presence of 10 mm Ba2+ the activation by MTX of the current was 50 % less than the activation with nm concentrations of free intracellular Ca2+. PMID:11773318

  18. Paliperidone increases spontaneous and evoked firing of mesocortical dopaminergic neurons by activating a hyperpolarization-activated inward current.

    PubMed

    Dong, Haiman; Wang, Qian; Zhu, Dexiao; Gao, Fei; Wang, Hui; Bao, Lihua; Zhang, Jing; Hu, Yanlai; Ding, Zhaoxi; Sun, Jinhao

    2016-10-01

    Mesocortical dopaminergic (DA) subtype neurons specifically project to the prefrontal cortex, which is closely related with schizophrenia. Mesocortical DA neurons have unique physiological characteristics that are different from those of mesostriatal and mesolimbic DA neurons. Paliperidone, an atypical antipsychotic, is currently used to treat schizophrenia and has better therapeutic effects than typical antipsychotics. However, the underlying physiological mechanism remains unclear. To explore the effects of paliperidone on mesocortical DA neuron activity, here, we retrogradely labeled these cells with fluorescent microsphere retrobeads, and the electrophysiological changes were recorded in whole-cell recordings in rat midbrain slices with or without paliperidone. The data showed that paliperidone (20μmol/L) increased the spontaneous firing rates of labeled mesocortical neurons (P<0.05). Moreover, paliperidone also increased the frequency of evoked action potentials by current injection stimulation (P<0.05), whereas the accompanying amplitude decreased. Furthermore, to explore the mechanisms of paliperidone's effect, Ih currents were detected, and the results showed that hyperpolarizing voltage pulses evoked instantaneous Ih inward currents and paliperidone increased the maximum Ih current. In addition, paliperidone decreased the spontaneous inhibitory postsynaptic currents. Thus, paliperidone increased the spontaneous and evoked firing of mesocortical neurons, possibly by activating the Ih inward current and reducing the inhibitory synaptic transmission, which provides an underlying mechanism of paliperidone's application in schizophrenia. PMID:27435059

  19. Three-dimensional ventricular activation imaging by means of equivalent current source modeling and estimation.

    PubMed

    Liu, Z; Liu, C; He, B

    2006-01-01

    This paper presents a novel electrocardiographic inverse approach for imaging the 3-D ventricular activation sequence based on the modeling and estimation of the equivalent current density throughout the entire myocardial volume. The spatio-temporal coherence of the ventricular excitation process is utilized to derive the activation time from the estimated time course of the equivalent current density. At each time instant during the period of ventricular activation, the distributed equivalent current density is noninvasively estimated from body surface potential maps (BSPM) using a weighted minimum norm approach with a spatio-temporal regularization strategy based on the singular value decomposition of the BSPMs. The activation time at any given location within the ventricular myocardium is determined as the time point with the maximum local current density estimate. Computer simulation has been performed to evaluate the capability of this approach to image the 3-D ventricular activation sequence initiated from a single pacing site in a physiologically realistic cellular automaton heart model. The simulation results demonstrate that the simulated "true" activation sequence can be accurately reconstructed with an average correlation coefficient of 0.90, relative error of 0.19, and the origin of ventricular excitation can be localized with an average localization error of 5.5 mm for 12 different pacing sites distributed throughout the ventricles.

  20. Simulation of Series Active and Passive Power Filter Combination System to Mitigate Current Source Harmonics

    NASA Astrophysics Data System (ADS)

    Yusof, Yushaizad; Rahim, Nasrudin Abd.

    2009-08-01

    This paper discusses a combination three phase system of series active power filter and passive power filter used to mitigate current source harmonics produced by a three phase diode rectifier with capacitive loads. A control method based on synchronous reference frame (SRF) is implemented to compensate for the current harmonics. Computer simulation and modelling of the combined filter system is carried out using Matlab/Simulink Power System Blockset (PSB) software. The single tuned passive power filters suppress 5th and 7th order current harmonics, while the series active power filter acts as a harmonic isolator between the source and load. Hence, the proposed system performs very well in mitigating source current harmonics to the level that comply the harmonic standard such as IEEE 519-1992.

  1. 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

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

    PubMed

    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

  3. 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.

  4. Activation of Ca(2+)-dependent K+ current by acetylcholine and histamine in a human gastric epithelial cell line

    PubMed Central

    1993-01-01

    The effects of acetylcholine (ACh) and histamine (His) on the membrane potential and current were examined in JR-1 cells, a mucin-producing epithelial cell line derived from human gastric signet ring cell carcinoma. The tight-seal, whole cell clamp technique was used. The resting membrane potential, the input resistance, and the capacitance of the cells were approximately -12 mV, 1.4 G ohms, and 50 pF, respectively. Under the voltage-clamp condition, no voltage-dependent currents were evoked. ACh or His added to the bathing solution hyperpolarized the membrane by activating a time- and voltage- independent K+ current. The ACh-induced hyperpolarization and K+ current persisted, while the His response desensitized quickly (< 1 min). These effects of ACh and His were mediated predominantly by m3- muscarinic and H1-His receptors, respectively. The K+ current induced by ACh and His was inhibited by charybdotoxin, suggesting that it is a Ca(2+)-activated K+ channel current (IK.Ca). The measurement of intracellular Ca2+ ([Ca2+]i) using Indo-1 revealed that both agents increased [Ca2+]i with similar time courses as they increased IK.Ca. When EGTA in the pipette solution was increased from 0.15 to 10 mM, the induction of IK.Ca by ACh and His was abolished. Thus, both ACh and His activate IK.Ca by increasing [Ca2+]i in JR-1 cells. In the Ca(2+)-free bathing solution (0.15 mM EGTA in the pipette), ACh evoked IK.Ca transiently. Addition of Ca2+ (1.8 mM) to the bath immediately restored the sustained IK.Ca. These results suggest that the ACh response is due to at least two different mechanisms; i.e., the Ca2+ release-related initial transient activation and the Ca2+ influx-related sustained activation of IK.Ca. Probably because of desensitization, the Ca2+ influx-related component of the His response could not be identified. Intracellularly applied inositol 1,4,5-trisphosphate (IP3), with and without inositol 1,3,4,5-tetrakisphosphate (IP4), mimicked the ACh response. IP4 alone

  5. 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.

  6. 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.

  7. 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.

  8. "Caged calcium" in Aplysia pacemaker neurons. Characterization of calcium-activated potassium and nonspecific cation currents

    PubMed Central

    1989-01-01

    We have studied calcium-activated potassium current, IK(Ca), and calcium-activated nonspecific cation current, INS(Ca), in Aplysia bursting pacemaker neurons, using photolysis of a calcium chelator (nitr-5 or nitr-7) to release "caged calcium" intracellularly. A computer model of nitr photolysis, multiple buffer equilibration, and active calcium extrusion was developed to predict volume-average and front-surface calcium concentration transients. Changes in arsenazo III absorbance were used to measure calcium concentration changes caused by nitr photolysis in microcuvettes. Our model predicted the calcium increments caused by successive flashes, and their dependence on calcium loading, nitr concentration, and light intensity. Flashes also triggered the predicted calcium concentration jumps in neurons filled with nitr-arsenazo III mixtures. In physiological experiments, calcium- activated currents were recorded under voltage clamp in response to flashes of different intensity. Both IK(Ca) and INS(Ca) depended linearly without saturation upon calcium concentration jumps of 0.1-20 microM. Peak membrane currents in neurons exposed to repeated flashes first increased and then declined much like the arsenazo III absorbance changes in vitro, which also indicates a first-order calcium activation. Each flash-evoked current rose rapidly to a peak and decayed to half in 3-12 s. Our model mimicked this behavior when it included diffusion of calcium and nitr perpendicular to the surface of the neuron facing the flashlamp. Na/Ca exchange extruding about 1 pmol of calcium per square centimeter per second per micromolar free calcium appeared to speed the decline of calcium-activated membrane currents. Over a range of different membrane potentials, IK(Ca) and INS(Ca) decayed at similar rates, indicating similar calcium stoichiometries independent of voltage. IK(Ca), but not INS(Ca), relaxes exponentially to a different level when the voltage is suddenly changed. We have estimated

  9. 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.

  10. 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.

  11. Single channel currents of different amplitude activated by glutamate in a tonic (slow) crayfish muscle.

    PubMed

    Finger, W; Pareto, A

    1987-09-11

    Single channel currents were recorded by means of the patch-clamp technique from a tonic (slow) crayfish muscle in the presence of 5 mM glutamate. The experiments were carried out with 'Gigaohm-seals' in the 'cell-attached' mode at 15-17 degrees C. Five classes of single channel currents with different mean amplitudes were resolved: i1 = -0.75 +/- 0.43 (S.D.) pA, i2 = -1.4 +/- 0.4 pA, i3 = -3.5 +/- 0.63 pA, i4 = -8.5 +/- 0.92 pA and i5 approximately equal to 2 X i4, i2, i3 and i4 were recorded at resting membrane potential, Eo approximately equal to -80 mV (pipette potential Vp = 0), while i1 and i5 were recorded at 40 mV hyperpolarized to Eo (Vp = +40 mV). The current most frequently seen was i4 which is the excitatory glutamate-activated single channel current recorded previously by Franke et al. The membrane reversal potentials and channel conductances for i2 and i4 were estimated to be +60 mV (Eo + 140 mV), 13 pS for i2 and +40 mV (Eo + 120 mV), 80 pS for i4. It was assumed that up to 40 i1 currents could superpose in a single patch to generate a DC current of up to -30 pA with current fluctuations the intensity of which increased with the DC current amplitude. Often variable combinations of i1 to i4 currents could be recorded simultaneously in a single patch. In particular, simultaneous activity of i1, i4; i2, i4 and i3, i4 currents was observed in different single patches.

  12. 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.

  13. Computational estimation of the distribution of L-type Ca(2+) channels in motoneurons based on variable threshold of activation of persistent inward currents.

    PubMed

    Bui, Tuan V; Ter-Mikaelian, Maria; Bedrossian, Diane; Rose, P Ken

    2006-01-01

    In the presence of neuromodulators such as serotonin and noradrenaline, motoneurons exhibit persistent inward currents (PICs) that serve to amplify synaptic inputs. A major component of these PICs is mediated by L-type Ca(2+) channels. Estimates based on electrophysiological studies indicate that these channels are located on the dendrites, but immunohistochemical studies of their precise distribution have yielded different results. Our goal was to determine the distribution of these channels using computational methods. A theoretical analysis of the activation of PICs by a somatic current injection in the absence or presence of synaptic activity suggests that L-type Ca(2+) channels may be segregated to discrete hot spots 25-200 microm long and centered 100-400 microm from the soma in the dendritic tree. Compartmental models based on detailed anatomical measurements of the structure of feline neck motoneurons with L-type Ca(2+) channels incorporated in these regions produced plateau potentials resulting from PIC activation. Furthermore, we replicated the experimental observation that the somatic threshold at which PICs were activated was depolarized by tonic activation of inhibitory synapses and hyperpolarized by tonic activation of excitatory synapses. Models with L-type Ca(2+) channels distributed uniformly were unable to replicate the change in somatic threshold of PIC activation. Therefore we conclude that the set of L-type Ca(2+) channels mediating plateau potentials is restricted to discrete regions in the dendritic tree. Furthermore, this distribution leads to the compartmentalization of the dendritic tree of motoneurons into subunits whose sequential activation lead to the graded amplification of synaptic inputs.

  14. Cell cycle-dependent activity of the volume- and Ca2+-activated anion currents in Ehrlich lettre ascites cells.

    PubMed

    Klausen, Thomas Kjaer; Bergdahl, Andreas; Hougaard, Charlotte; Christophersen, Palle; Pedersen, Stine F; Hoffmann, Else K

    2007-03-01

    Recent evidence implicates the volume-regulated anion current (VRAC) and other anion currents in control or modulation of cell cycle progression; however, the precise involvement of anion channels in this process is unclear. Here, Cl- currents in Ehrlich Lettre Ascites (ELA) cells were monitored during cell cycle progression, under three conditions: (i) after osmotic swelling (i.e., VRAC), (ii) after an increase in the free intracellular Ca2+ concentration (i.e., the Ca2+-activated Cl- current, CaCC), and (iii) under steady-state isotonic conditions. The maximal swelling-activated VRAC current decreased in G1 and increased in early S phase, compared to that in G0. The isotonic steady-state current, which seems to be predominantly VRAC, also decreased in G1, and increased again in early S phase, to a level similar to that in G0. In contrast, the maximal CaCC current (500 nM free Ca2+ in the pipette), was unaltered from G0 to G1, but decreased in early S phase. A novel high-affinity anion channel inhibitor, the acidic di-aryl-urea NS3728, which inhibited both VRAC and CaCC, attenuated ELA cell growth, suggesting a possible mechanistic link between cell cycle progression and cell cycle-dependent changes in the capacity for conductive Cl- transport. It is suggested that in ELA cells, entrance into the S phase requires an increase in VRAC activity and/or an increased potential for regulatory volume decrease (RVD), and at the same time a decrease in CaCC magnitude. PMID:17111356

  15. Induction of self awareness in dreams through frontal low current stimulation of gamma activity.

    PubMed

    Voss, Ursula; Holzmann, Romain; Hobson, Allan; Paulus, Walter; Koppehele-Gossel, Judith; Klimke, Ansgar; Nitsche, Michael A

    2014-06-01

    Recent findings link fronto-temporal gamma electroencephalographic (EEG) activity to conscious awareness in dreams, but a causal relationship has not yet been established. We found that current stimulation in the lower gamma band during REM sleep influences ongoing brain activity and induces self-reflective awareness in dreams. Other stimulation frequencies were not effective, suggesting that higher order consciousness is indeed related to synchronous oscillations around 25 and 40 Hz.

  16. 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.

  17. 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.

  18. Active Flow Control of Lifting Surface With Flap-Current Activities and Future Directions

    NASA Technical Reports Server (NTRS)

    Ahmadi, G.; Marzocca, P.; Jha, R.; Alstorm, B.; Obied, S.; Kabir, P.; Shahrabi, A.

    2010-01-01

    The main objective is to develop effective control strategies for separation control of an airfoil with a single hinge flap. The specific objectives are: Develop an active control architecture for flow control around an airfoil with flap. Design, fabricate, a wind tunnel test of a high lift wing (with flap) with integrated actuators and sensors. Design, development and fabrication of synthetic jet actuators. Develop appropriate control strategy for application to the airfoil. Wind tunnel testing of the high lift wing at various angles of attack and flap positions with closed loop control.

  19. 78 FR 76391 - Agency Information Collection Activities: Notice of Request for Extension of Currently Approved...

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  2. 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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  14. 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.

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

    DOE PAGES

    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

  16. 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.

  17. Analysis of G-protein-activated inward rectifying K(+) (GIRK) channel currents upon GABAB receptor activation in rat supraoptic neurons.

    PubMed

    Harayama, Nobuya; Kayano, Tomohiko; Moriya, Taiki; Kitamura, Naoki; Shibuya, Izumi; Tanaka-Yamamoto, Keiko; Uezono, Yasuhito; Ueta, Yoichi; Sata, Takeyoshi

    2014-12-01

    While magnocellular neurons in the supraoptic nucleus (SON) possess rich Gi/o-mediated mechanisms, molecular and cellular properties of G-protein-activated inwardly rectifying K(+) (GIRK) channels have been controversial. Here, properties of GIRK channels are examined by RT-PCR and whole-cell patch-clamp techniques in rat SON neurons. Patch clamp experiments showed that the selective GABAB agonist, baclofen, enhanced currents in a high K(+) condition. The baclofen-enhanced currents exhibited evident inward rectification and were blocked by the selective GABAB antagonist, CGP55845A, the IRK channel blocker, Ba(2+), and the selective GIRK channel blocker, tertiapin, indicating that baclofen activates GIRK channels via GABAB receptors. The GIRK currents were abolished by N-ethylmaleimide pretreatment, and prolonged by GTPγS inclusion in the patch pipette, suggesting that Gi/o proteins are involved. RT-PCR analysis revealed mRNAs for all four GIRK 1-4 channels and for both GABABR1 and GABABR2 receptors in rat SON. However, the concentration-dependency of the baclofen-induced activation of GIRK currents had an EC50 of 110 µM, which is about 100 times higher than that of baclofen-induced inhibition of voltage-dependent Ca(2+) channels. Moreover, baclofen caused no significant changes in the membrane potential and the firing rate. These results suggest that although GIRK channels can be activated by GABAB receptors via the Gi/o pathway, this occurs at high agonist concentrations, and thus may not be a physiological mechanism regulating the function of SON neurons. This property that the membrane potential receives little influence from GIRK currents seems to be uncommon for CNS neurons possessing rich Gi/o-coupled receptors, and could be a special feature of rat SON neurons.

  18. Field-aligned current signatures during auroral activations of Feb. 16, 0220 UT substorm

    NASA Astrophysics Data System (ADS)

    Nakamura, R.; Angelopoulos, V.; Frey, H.; Auster, U.

    2009-04-01

    Two auroral activations with poleward/equatorward expansion were observed starting around 0216 UT and 0243 UT on 16 Feb 2008, when the five THEMIS spacecraft were distributed in the premidnight to midnight (22-24 MLT) region between 8 and 18 RE downtail. We compare and contrast the possible field-aligned current signatures associated with dipolarization accompanied by Earthward flows observed at the THD(P3) and THE(P4) spacecraft in the premidnight sector at downtail distances between 8 and 9 RE by referring also to the mid-tail spacecraft, THC(P2) and THB(P1), which provide information on the current sheet configuration. Both dipolarization events started from the tailward side, THD(P3), but had quite different profiles in the magnetic shear components relevant to the field aligned current, as well as in the magnetotail current sheet configuration and auroral signatures. The 0216 UT event occurred in a thinner near-Earth current sheet condition and THD(P3) and THE(P4) detected dipolarization accompanied by fast flows and enhanced shear in the magnetic field, while conjugate ground signatures suggest development of a slant North-south aligned aurora, east of a small surge. During the 0243 UT event, X-line signatures at a midtail thin current sheet were observed, followed by a large-scale plasma sheet expansion and the associated auroral activation took place more poleward. Dipolarization was again observed at THD(P3) and THE(P4) but accompanied by less significant shear component and delay in the fast flow signatures compared to the magnetic signatures. We discuss these two different dipolarization/field aligned current signatures in terms of different stages of the fast flows interacting with the ambient field in a different configuration of the tail current sheet.

  19. Deletion of the Slo3 gene abolishes alkalization-activated K+ current in mouse spermatozoa.

    PubMed

    Zeng, Xu-Hui; Yang, Chengtao; Kim, Sung Tae; Lingle, Christopher J; Xia, Xiao-Ming

    2011-04-01

    Mouse spermatozoa express a pH-dependent K(+) current (KSper) thought to be composed of subunits encoded by the Slo3 gene. However, the equivalence of KSper and Slo3-dependent current remains uncertain, because heterologous expression of Slo3 results in currents that are less effectively activated by alkalization than are native KSper currents. Here, we show that genetic deletion of Slo3 abolishes all pH-dependent K(+) current at physiological membrane potentials in corpus epididymal sperm. A residual pH-dependent outward current (I(Kres)) is observed in Slo3(-/-) sperm at potentials of >0 mV. Differential inhibition of KSper/Slo3 and I(Kres) by clofilium reveals that the amplitude of I(Kres) is similar in both wild-type (wt) and Slo3(-/-) sperm. The properties of I(Kres) suggest that it likely represents outward monovalent cation flux through CatSper channels. Thus, KSper/Slo3 may account for essentially all mouse sperm K(+) current and is the sole pH-dependent K(+) conductance in these sperm. With physiological ionic gradients, alkalization depolarizes Slo3(-/-) spermatozoa, presumably from CatSper activation, in contrast to Slo3/KSper-mediated hyperpolarization in wt sperm. Slo3(-/-) male mice are infertile, but Slo3(-/-) sperm exhibit some fertility within in vitro fertilization assays. Slo3(-/-) sperm exhibit a higher incidence of morphological abnormalities accentuated by hypotonic challenge and also exhibit deficits in motility in the absence of bicarbonate, revealing a role of KSper under unstimulated conditions. Together, these results show that KSper/Slo3 is the primary spermatozoan K(+) current, that KSper may play a critical role in acquisition of normal morphology and sperm motility when faced with hyperosmotic challenges, and that Slo3 is critical for fertility. PMID:21427226

  20. Development of voltage-activated potassium currents in cultured cerebellar granule neurons under different growth conditions.

    PubMed

    Gorter, J A; Aronica, E; Hack, N J; Balázs, R; Wadman, W J

    1995-07-01

    1. The functional expression of two potassium currents in cultured cerebellar granule cells was investigated with the whole cell patch-clamp technique in relation to development and growth condition. Cells were grown in medium containing different concentrations of potassium: 25 mM (K25) and 40 mM (K40), together referred to as "high K+"; 10 mM (K10) or "low K+"; and K10 with 100 microM N-methyl-D-aspartate (KNMDA). All conditions are known to influence maturation and survival of granule cells in culture. 2. At 2 days in vitro (DIV) the membrane capacitance, taken as index of membrane surface area, was the same for cells grown in each growth condition. At 7-9 DIV it had increased in each condition, but to a substantially larger extent in cells grown in KNMDA, K25, and K40 than in cells grown in K10. During development the input resistance only decreased in cells grown in KNMDA and high K+. 3. A delayed potassium current (IK) and a fast transient potassium current (IA) could both be recorded at 2 DIV in each growth condition, although a few neurons only expressed the IK. The IK was partially suppressed by tetraethylammonium (5 mM), whereas IA was predominantly sensitive to 4-aminopyridine (5 mM). 4. Normalized for cell capacitance, the specific IA conductance hardly changed during development in cells grown in high K+ and KNMDA. Cells in K10, however, displayed an IA with totally different properties in 23 of 24 cells; the specific IA conductance in these cells was considerably smaller at 7-9 DIV, suggesting a deletion of these channels during development.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. 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.

  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. 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).

  4. The relation between membrane potential, membrane currents and activation of contraction in ventricular myocardial fibres

    PubMed Central

    Beeler, G. W.; Reuter, H.

    1970-01-01

    1. Membrane currents and contractile responses have been measured in ventricular myocardial preparations under voltage clamp conditions. 2. In Tyrode solution, steady-state contraction was obtained only after 5-8 depolarizations to a given potential level. The threshold of steady-state tension was identical to the potential where the calcium inward current, ICa, was activated (about -35 mV). Both thresholds were shifted in the same direction along the voltage axis and by the same amount by changing [Ca]o or [Na]o. Maximum tension was obtained at inside positive potentials. 3. The time courses of steady-state tension and of activation of ICa were different by more than one order of magnitude in Tyrode solution. But in order to achieve any appreciable steady-state tension, ICa had to flow during several identical depolarizations. Tension decreased again at potentials above ECa. This suggests that calcium inward current must flow in order to fill intracellular calcium stores from which calcium can be released by an unknown mechanism. 4. The ability of a fibre bundle to contract again after a preceding twitch is greatly dependent on the membrane potential between two equal depolarizations. In Tyrode solutions with 1·8 and 7·2 mM-CaCl2 half restoration of this ability occurred at -45 ± 3 mV (± S.E. of mean) and -23 ± 4 mV, respectively. 5. In sodium-free bathing solutions, steady-state tension was attained upon the first depolarization provided ICa was activated. Furthermore, at different potentials, the time courses of activation of tension and of activation of ICa were identical, i.e. tension reached its maximum when ICa was fully activated. This suggests that in sodium-free solutions the flow of calcium ions into the fibre directly activates contraction. PMID:5503873

  5. The current status and future applicability of quantitative structure-activity relationships (QSARs) in predicting toxicity.

    PubMed

    Cronin, Mark T D

    2002-12-01

    The current status of quantitative structure-activity relationships (QSARs) in predicting toxicity is assessed. Widespread use of these methods to predict toxicity from chemical structure is possible, both by industry to develop new compounds, and also by regulatory agencies. The current use of QSARs is restricted by the lack of suitable toxicity data available for modelling, the suitability of simplistic modelling approaches for the prediction of certain endpoints, and the poor definition and utilisation of the applicability domain of models. Suggestions to resolve these issues are made.

  6. Preface: Special Session SpS7 The impact hazard: current activities and future plans

    NASA Astrophysics Data System (ADS)

    Montmerle, Thierry

    2015-03-01

    In 2012, at the time of the Beijing GA, two decades had passed since the publication of the Spaceguard Report. Time has not passed in vain for the subject of NEO-related hazards, and we are currently in a totally different situation than in the early nineties. The amount of work done, and the level of awareness of the underlying problems, have both risen to such a level that a re-assessment by the astronomical community of its rôle and involvement was in order, and the GA Special Session 7 ``The impact hazard: current activities and future plans'' was aimed exactly at that.

  7. Flux emergence in the solar active region NOAA 11158: the evolution of net current

    NASA Astrophysics Data System (ADS)

    Vemareddy, Panditi; Venkatakrishnan, Parameswaran; Karthikreddy, Solipuram

    2015-09-01

    We present a detailed investigation of the evolution of observed net vertical current using a time series of vector magnetograms of the active region (AR) NOAA 11158 obtained from the Helioseismic and Magnetic Imager. We also discuss the relation of net current to the observed eruptive events. The AR evolved from the βγ to βγδ configuration over a period of six days. The AR had two sub-regions of activity with opposite chirality: one dominated by sunspot rotation producing a strong CME, and the other showing large shear motions producing a strong flare. The net current in each polarity over the CME producing sub-region increased to a maximum and then decreased when the sunspots were separated. The time profile of net current in this sub-region followed the time profile of the rotation rate of the south-polarity sunspot in the same sub-region. The net current in the flaring sub-region showed a sudden increase at the time of the strong flare and remained unchanged until the end of the observation, while the sunspots maintained their close proximity. The systematic evolution of the observed net current is seen to follow the time evolution of total length of strongly sheared polarity inversion lines in both of the sub-regions. The observed photospheric net current could be explained as an inevitable product of the emergence of a twisted flux rope, from a higher pressure confinement below the photosphere into the lower pressure environment of the photosphere.

  8. Input characterization of a shock test strructure.

    SciTech Connect

    Hylok, J. E.; Groethe, M. A.; Maupin, R. D.

    2004-01-01

    Often in experimental work, measuring input forces and pressures is a difficult and sometimes impossible task. For one particular shock test article, its input sensitivity required a detailed measurement of the pressure input. This paper discusses the use of a surrogate mass mock test article to measure spatial and temporal variations of the shock input within and between experiments. Also discussed will be the challenges and solutions in making some of the high speed transient measurements. The current input characterization work appears as part of the second phase in an extensive model validation project. During the first phase, the system under analysis displayed sensitivities to the shock input's qualitative and quantitative (magnitude) characteristics. However, multiple shortcomings existed in the characterization of the input. First, the experimental measurements of the input were made on a significantly simplified structure only, and the spatial fidelity of the measurements was minimal. Second, the sensors used for the pressure measurement contained known errors that could not be fully quantified. Finally, the measurements examined only one input pressure path (from contact with the energetic material). Airblast levels from the energetic materials were unknown. The result was a large discrepancy between the energy content in the analysis and experiments.

  9. 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

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

    PubMed

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

    2013-09-11

    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.

  11. 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

  12. Effect of Direct-Current Electric Field on Enzymatic Activity and the Concentration of Laccase.

    PubMed

    Wang, Chunxing; Zhang, Huiling; Ren, Dajun; Li, Qian; Zhang, Shuqin; Feng, Tao

    2015-09-01

    This work investigates the effect of direct-current electric field on the extracellular enzymatic activity, concentration and other experimental parameters of laccase from Trametes versicolor. The results showed that laccase could significantly contribute to the change of pH at the end of graphite electrode. In addition, it increased the electrical conductivity of the water. In the experiment, the optimum pH and catalytic pH range for laccase activity were 3.0 and pH 2.5-4.0. The application of 6 V direct current showed significant effects on the laccase enzyme activity. The activity of laccase was enhanced in the anodic region, but at the same time was strongly inhibited at the cathode. The electric charge characteristics of laccase were changed when exposed to electric field, and some laccases molecules moved to the anode, which produced a slight migration phenomenon. This study is the basis of combination of laccase and electrical technology, at the same time, providing a new direction of enhancing laccase activity. Compared to immobilization, using electric field is simple, no chemical additives, and great potential.

  13. 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.

  14. 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)

  15. 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.

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

    PubMed

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

    2016-06-01

    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

  17. 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

  18. Polarographic study of hydrogen peroxide anodic current and its application to antioxidant activity determination.

    PubMed

    Sužnjević, Desanka Ž; Pastor, Ferenc T; Gorjanović, Stanislava Ž

    2011-09-15

    Behavior of hydrogen peroxide in alkaline medium has been studied by direct current (DC) polarography with dropping mercury electrode (DME) aiming to apply it in antioxidant (AO) activity determination. Development of a peroxide anodic current having form of a peak, instead of common polarographic wave, has been investigated. As a base for this investigation the interaction of H(2)O(2) with anodically dissolved mercury was followed. Formation of mercury complex [Hg(O(2)H)(OH)] has been confirmed. The relevant experimental conditions, such as temperature, concentration and pH dependence, as well as time stability of hydrogen peroxide anodic current, have been assessed. Development of an AO assay based on decrease of anodic current of hydrogen peroxide in the presence of antioxidants (AOs) has been described. Under optimized working conditions, a series of benzoic acids along with corresponding cinnamate analogues have been tested for hydrogen peroxide scavenging activity. In addition, the assay versatility has been confirmed on various complex samples.

  19. 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.

  20. 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

  1. 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

  2. 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

  3. 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.

  4. 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

  5. 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

  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. 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.

  8. Effects of antiarrhythmic drugs on the hyperpolarization-activated cyclic nucleotide-gated channel current.

    PubMed

    Tamura, Atsushi; Ogura, Takehiko; Uemura, Hiroko; Reien, Yoshie; Kishimoto, Takashi; Nagai, Toshio; Komuro, Issei; Miyazaki, Masaru; Nakaya, Haruaki

    2009-06-01

    After the report of the Cardiac Arrhythmia Suppression Trial, a tabular framework of the Sicilian Gambit has been proposed to display actions of antiarrhythmic drugs on ion channels and receptors and to provide more rational pharmacotherapy of arrhythmias. However, because effects of antiarrhythmic drugs on If have not been thoroughly examined, we used patch clamp techniques to determine the effects of various antiarrhythmic drugs on the HCN (hyperpolarization-activated cyclic nucleotide-gated) channel currents. HCN4 channels, a dominant isoform of HCN channels in the heart, were expressed in HEK293 cells. Amiodarone and bepridil potently inhibited the HCN4 channel current with IC50 values of 4.5 and 4.9 microM, respectively, which were close to their therapeutic concentrations. The inhibitory effects of quinidine, disopyramide, cibenzoline, lidocaine, mexiletine, aprindine, propafenone, flecainide, propranolol, and verapamil on the HCN4 channel current were weak in their therapeutic concentrations, with IC50 values of 78.3, 249, 46.8, 276, 309, 43.7, 14.3, 1700, 50.5, and 44.9 microM, respectively, suggesting that the inhibitory effects on If would be clinically small. D,L-Sotalol hardly affected the HCN4 channel current. Information about the HCN4-channel effects of many antiarrhythmic drugs may be useful for determining the appropriate drug for treatment of various arrhythmias while minimizing adverse effects. PMID:19498275

  9. Voltage-activated sodium current is inhibited by capsaicin in rat atrial myocytes.

    PubMed

    Milesi, V; Rebolledo, A; Alvis, A G; Raingo, J; Grassi de Gende, A O

    2001-04-13

    The effects of capsaicin, the active principle of hot pepper genus Capsicum, were studied on voltage-activated, tetrodotoxin-sensitive Na+ currents in isolated rat atrial cells using the patch clamp technique in the whole-cell configuration. 0.4 and 4 microM of capsaicin produced a significant tonic block on voltage-activated Na+ current (I(Na)) evoked by a depolarizing step to -40 mV from a holding potential of -100 mV (49 +/- 7% n = 11, P < 0.05 and 72 +/- 13% n = 4, P < 0.05 respectively). We didn't observe any use-dependent block of capsaicin in our experimental conditions. Capsaicin slowed the time decay of inactivation of I(Na), and increased the time constant of the recovery of inactivation. Capsaicin and tetrodotoxin (TTX) depressed contractility of isolated electrically driven left rat atria, being the depression of maximal velocity of force development (dF/dt(max)) with respect to control values of 19 +/- 3% at 1 microM of capsaicin and 22 +/- 2% at 1 microM of TTX. These results show an inhibitory effect of capsaicin on I(Na) in isolated atrial cells that may modify the electrical and contractile function of the rat heart. PMID:11352646

  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. GABA transporter currents activated by protein kinase A excite midbrain neurons during opioid withdrawal.

    PubMed

    Bagley, Elena E; Gerke, Michelle B; Vaughan, Christopher W; Hack, Stephen P; Christie, MacDonald J

    2005-02-01

    Adaptations in neurons of the midbrain periaqueductal gray (PAG) induced by chronic morphine treatment mediate expression of many signs of opioid withdrawal. The abnormally elevated action potential rate of opioid-sensitive PAG neurons is a likely cellular mechanism for withdrawal expression. We report here that opioid withdrawal in vitro induced an opioid-sensitive cation current that was mediated by the GABA transporter-1 (GAT-1) and required activation of protein kinase A (PKA) for its expression. Inhibition of GAT-1 or PKA also prevented withdrawal-induced hyperexcitation of PAG neurons. Our findings indicate that GAT-1 currents can directly increase the action potential rates of neurons and that GAT-1 may be a target for therapy to alleviate opioid-withdrawal symptoms.

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. What are the implications of rapid global warming for landslide-triggered turbidity current activity?

    NASA Astrophysics Data System (ADS)

    Clare, Michael; Peter, Talling; James, Hunt

    2014-05-01

    A geologically short-lived (~170kyr) episode of global warming occurred at ~55Ma, termed the Initial Eocene Thermal Maximum (IETM). Global temperatures rose by up to 8oC over only ~10kyr and a massive perturbation of the global carbon cycle occurred; creating a negative carbon isotopic (~-4% δ13C) excursion in sedimentary records. This interval has relevance to study of future climate change and its influence on geohazards including submarine landslides and turbidity currents. We analyse the recurrence frequency of turbidity currents, potentially initiated from large-volume slope failures. The study focuses on two sedimentary intervals that straddle the IETM and we discuss implications for turbidity current triggering. We present the results of statistical analyses (regression, generalised linear model, and proportional hazards model) for extensive turbidite records from an outcrop at Zumaia in NE Spain (N=285; 54.0 to 56.5 Ma) and based on ODP site 1068 on the Iberian Margin (N=1571; 48.2 to 67.6 Ma). The sedimentary sequences provide clear differentiation between hemipelagic and turbiditic mud with only negligible evidence of erosion. We infer dates for turbidites by converting hemipelagic bed thicknesses to time using interval-averaged accumulation rates. Multi-proxy dating techniques provide good age constraint. The background trend for the Zumaia record shows a near-exponential distribution of turbidite recurrence intervals, while the Iberian Margin shows a log-normal response. This is interpreted to be related to regional time-independence (exponential) and the effects of additive processes (log-normal). We discuss how a log-normal response may actually be generated over geological timescales from multiple shorter periods of random turbidite recurrence. The IETM interval shows a dramatic departure from both these background trends, however. This is marked by prolonged hiatuses (0.1 and 0.6 Myr duration) in turbidity current activity in contrast to the

  17. 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.

  18. 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.

  19. Modification of activated sludge properties caused by application of continuous and intermittent current.

    PubMed

    Ibeid, S; Elektorowicz, M; Oleszkiewicz, J A

    2013-02-01

    This study investigated the impact of direct current (DC) field on the activated sludge properties for potential improvement of the biological as well as membrane treatment processes. Three mixed-liquor suspended solids (MLSS) concentrations (5,000, 10,000 and 15,000 mg/l) were subjected to current densities (CD) ranging from 5 to 50 A/m² at five electrical exposure modes (time-ON/time-OFF). The results showed that CD between 15 and 35 A/m² increased the filterability of the sludge more than 200 times when compared with the untreated reference sludge. The average removals of protein, polysaccharides and organic colloids from the sludge supernatant at this range of CD were 43%, 73% and 91%, respectively, while the average reduction of the specific resistance to filtration (SRF) was 4.8 times higher. The changes of sludge properties depended on the current density, electrical exposure mode and the MLSS concentration. At CD of 25 A/m² and MLSS below 10,000 mg/l, shorter time-OFF was needed in each electrical cycle, while more time-OFF was needed at higher MLSS concentrations. It was concluded that proper application of the DC field could improve biomass in terms of its dewaterability and the removal of SMP, which are highly correlated to membrane fouling in the submerged membrane electro-bioreactor (SMEBR).

  20. 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

  1. 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.

  2. 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

  3. 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.

  4. HIV-1 Tat Protein Increases Microglial Outward K+ Current and Resultant Neurotoxic Activity

    PubMed Central

    Liu, Jianuo; Xu, Peng; Collins, Cory; Liu, Han; Zhang, Jingdong; Keblesh, James P.; Xiong, Huangui

    2013-01-01

    Microglia plays a crucial role in the pathogenesis of HIV-1-associated neurocognitive disorders. Increasing evidence indicates the voltage-gated potassium (Kv) channels are involved in the regulation of microglia function, prompting us to hypothesize Kv channels may also be involved in microglia-mediated neurotoxic activity in HIV-1-infected brain. To test this hypothesis, we investigated the involvement of Kv channels in the response of microglia to HIV-1 Tat protein. Treatment of rat microglia with HIV-1 Tat protein (200 ng/ml) resulted in pro-inflammatory microglial activation, as indicated by increases in TNF-α, IL-1β, reactive oxygen species, and nitric oxide, which were accompanied by enhanced outward K+ current and Kv1.3 channel expression. Suppression of microglial Kv1.3 channel activity, either with Kv1.3 channel blockers Margatoxin, 5-(4-Phenoxybutoxy)psoralen, or broad-spectrum K+ channel blocker 4-Aminopyridine, or by knockdown of Kv1.3 expression via transfection of microglia with Kv1.3 siRNA, was found to abrogate the neurotoxic activity of microglia resulting from HIV-1 Tat exposure. Furthermore, HIV-1 Tat-induced neuronal apoptosis was attenuated with the application of supernatant collected from K+ channel blocker-treated microglia. Lastly, the intracellular signaling pathways associated with Kv1.3 were investigated and enhancement of microglial Kv1.3 was found to correspond with an increase in Erk1/2 mitogen-activated protein kinase activation. These data suggest targeting microglial Kv1.3 channels may be a potential new avenue of therapy for inflammation-mediated neurological disorders. PMID:23738010

  5. 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.

  6. Pacemaker activity of the human sinoatrial node: effects of HCN4 mutations on the hyperpolarization-activated current.

    PubMed

    Verkerk, Arie O; Wilders, Ronald

    2014-03-01

    The hyperpolarization-activated 'funny' current, If, plays an important modulating role in the pacemaker activity of the human sinoatrial node (SAN). If is carried by hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which are tetramers built of four HCN subunits. In human SAN, HCN4 is the most abundant of the four isoforms of the HCN family. Since 2003, several loss-of-function mutations in the HCN4 gene, which encodes the HCN4 protein, or in the KCNE2 gene, which encodes the MiRP1 accessory β-subunit, have been associated with sinus node dysfunction. Voltage-clamp experiments on HCN4 channels expressed in COS-7 cells, Xenopus oocytes, or HEK-293 cells have revealed changes in the expression and kinetics of mutant channels, but the extent to which these changes would affect If flowing during a human SAN action potential is unresolved. Here, we review the changes in expression and kinetics of HCN4 mutant channels and provide an overview of their effects on If during the time course of a human SAN action potential, both under resting conditions and upon adrenergic stimulation. These effects are assessed in simulated action potential clamp experiments, with action potentials recorded from isolated human SAN pacemaker cells as command potential and kinetics of If based on voltage-clamp data from these cells. Results from in vitro and in silico experiments show several inconsistencies with clinical observations, pointing to challenges for future research.

  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. Nitric oxide activates leak K+ currents in the presumed cholinergic neuron of basal forebrain.

    PubMed

    Kang, Youngnam; Dempo, Yoshie; Ohashi, Atsuko; Saito, Mitsuru; Toyoda, Hiroki; Sato, Hajime; Koshino, Hisashi; Maeda, Yoshinobu; Hirai, Toshihiro

    2007-12-01

    Learning and memory are critically dependent on basal forebrain cholinergic (BFC) neuron excitability, which is modulated profoundly by leak K(+) channels. Many neuromodulators closing leak K(+) channels have been reported, whereas their endogenous opener remained unknown. We here demonstrate that nitric oxide (NO) can be the endogenous opener of leak K(+) channels in the presumed BFC neurons. Bath application of 1 mM S-nitroso-N-acetylpenicillamine (SNAP), an NO donor, induced a long-lasting hyperpolarization, which was often interrupted by a transient depolarization. Soluble guanylyl cyclase inhibitors prevented SNAP from inducing hyperpolarization but allowed SNAP to cause depolarization, whereas bath application of 0.2 mM 8-bromoguanosine-3',5'-cyclomonophosphate (8-Br-cGMP) induced a similar long-lasting hyperpolarization alone. These observations indicate that the SNAP-induced hyperpolarization and depolarization are mediated by the cGMP-dependent and -independent processes, respectively. When examined with the ramp command pulse applied at -70 mV under the voltage-clamp condition, 8-Br-cGMP application induced the outward current that reversed at K(+) equilibrium potential (E(K)) and displayed Goldman-Hodgkin-Katz rectification, indicating the involvement of voltage-independent K(+) current. By contrast, SNAP application in the presumed BFC neurons either dialyzed with the GTP-free internal solution or in the presence of 10 muM Rp-8-bromo-beta-phenyl-1,N(2)-ethenoguanosine 3',5'-cyclic monophosphorothioate sodium salt, a protein kinase G (PKG) inhibitor, induced the inward current that reversed at potentials much more negative than E(K) and close to the reversal potential of Na(+)-K(+) pump current. These observations strongly suggest that NO activates leak K(+) channels through cGMP-PKG-dependent pathway to markedly decrease the excitability in BFC neurons, while NO simultaneously causes depolarization by the inhibition of Na(+)-K(+) pump through ATP

  9. 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.

  10. Low-Power Magnetic Current Sensor

    NASA Technical Reports Server (NTRS)

    Mclyman, W. T.

    1989-01-01

    Direct current sensed via saturable-core reactor. Transducer senses direct current magnetically, providing isolation between input and output. Detecting-and-isolating element saturable reactor, where input current passes through one-turn control coil. Provides output of 0 to 3 Vdc for input current of 0 to 15 Adc and consumes power of 22 mW at 10 Adc input. Input sensed magnetically, output electrically isolated from input.

  11. Nutrition and Physical Activity Strategies for Cancer Prevention in Current National Comprehensive Cancer Control Program Plans.

    PubMed

    Puckett, Mary; Neri, Antonio; Underwood, J Michael; Stewart, Sherri L

    2016-10-01

    Obesity, diet and physical inactivity are risk factors for some cancers. Grantees of the National Comprehensive Cancer Control Program (NCCCP) in US states, tribes, and territories develop plans to coordinate funding and activities for cancer prevention and control. Including information and goals related to nutrition and physical activity (NPA) is a key opportunity for primary cancer prevention, but it is currently unclear to what extent NCCCP plans address these issues. We reviewed 69 NCCCP plans and searched for terms related to NPA. Plans were coded as (1) knowledge of NPA and cancer link; (2) goals to improve NPA behaviors; and (3) strategies to increase healthy NPA activities, environments, or systems changes. NPA content was consistently included in all cancer plans examined across all years. Only 4 (6 %) outlined only the relationship between NPA and cancer without goals or strategies. Fifty-nine plans (89 %) contained goals or strategies related to NPA, with 53 (82 %) including both. However, numbers of goals, strategies, and detail provided varied widely. All programs recognized the importance of NPA in cancer prevention. Most plans included NPA goals and strategies. Increasing the presence of NPA strategies that can be modified or adapted appropriately locally could help with more widespread implementation and measurement of NPA interventions.

  12. 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.

  13. Arbuscular mycorrhizal symbiosis and active ingredients of medicinal plants: current research status and prospectives.

    PubMed

    Zeng, Yan; Guo, Lan-Ping; Chen, Bao-Dong; Hao, Zhi-Peng; Wang, Ji-Yong; Huang, Lu-Qi; Yang, Guang; Cui, Xiu-Ming; Yang, Li; Wu, Zhao-Xiang; Chen, Mei-Lan; Zhang, Yan

    2013-05-01

    Medicinal plants have been used world-wide for thousands of years and are widely recognized as having high healing but minor toxic side effects. The scarcity and increasing demand for medicinal plants and their products have promoted the development of artificial cultivation of medicinal plants. Currently, one of the prominent issues in medicinal cultivation systems is the unstable quality of the products. Arbuscular mycorrhiza (AM) affects secondary metabolism and the production of active ingredients of medicinal plants and thus influence the quality of herbal medicines. In this review, we have assembled, analyzed, and summarized the effects of AM symbioses on secondary metabolites of medicinal plants. We conclude that symbiosis of AM is conducive to favorable characteristics of medicinal plants, by improving the production and accumulation of important active ingredients of medicinal plants such as terpenes, phenols, and alkaloids, optimizing the composition of different active ingredients in medicinal plants and ultimately improving the quality of herbal materials. We are convinced that the AM symbiosis will benefit the cultivation of medicinal plants and improve the total yield and quality of herbal materials. Through this review, we hope to draw attention to the status and prospects of, and arouse more interest in, the research field of medicinal plants and mycorrhiza.

  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. 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

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. Activity-dependent alternative splicing increases persistent sodium current and promotes seizure

    PubMed Central

    Lin, Wei-Hsiang; Günay, Cengiz; Marley, Richard; Prinz, Astrid A.; Baines, Richard A.

    2012-01-01

    Activity of voltage-gated Na channels (Nav) is modified by alternative splicing. However, whether altered splicing of human Nav’s contributes to epilepsy remains to be conclusively shown. We show here that altered splicing of the Drosophila Nav (paralytic, DmNav) contributes to seizure-like behaviour in identified seizure-mutants. We focus attention on a pair of mutually-exclusive alternate exons (termed K and L), which form part of the voltage sensor (S4) in domain III of the expressed channel. The presence of exon L results in a large, non-inactivating, persistent INap. Many forms of human epilepsy are associated with an increase in this current. In wildtype (WT) Drosophila larvae ~70-80% of DmNav transcripts contain exon L, the remainder contain exon K. Splicing of DmNav to include exon L is increased to ~100% in both the slamdance and easily-shocked seizure-mutants. This change to splicing is prevented by reducing synaptic activity levels through exposure to the antiepileptic phenytoin or the inhibitory transmitter GABA. Conversely, enhancing synaptic activity in WT, by feeding of picrotoxin, is sufficient to increase INap and promote seizure through increased inclusion of exon L to 100%. We also show that the underlying activity-dependent mechanism requires the presence of Pasilla, an RNA-binding protein. Finally, we use computational modelling to show that increasing INap is sufficient to potentiate membrane excitability consistent with a seizure phenotype. Thus, increased synaptic excitation favors inclusion of exon L which, in turn, further increases neuronal excitability. Thus, at least in Drosophila, this self-reinforcing cycle may promote the incidence of seizure. PMID:22623672

  1. 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

  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. Building profile input program - a standardized method for calculating building downwash input values

    SciTech Connect

    Eckhoff, P.A.

    1994-12-31

    Building downwash is a complex technical subject that has important ramifications in the field of air quality dispersion modeling. Building downwash algorithms have been incorporated into air quality dispersion models such as the Industrial Source Complex (ISC2) Models, short term and long term versions (ISCST2 and ISCLT2). Input data preparation for these algorithms must reflect Environmental Protection Agency (EPA) guidance on Good Engineering Practice (GEP) stack height and building downwash. The current guidance is complex and errors can easily be made in the input data preparation. A computer program called the Building Profile Input Program (BPIP) was written to alleviate errors caused during input data preparation and to provide a standardized method for calculating building height (BH) and projected building width (PBW) values for input to the ISC2 models that reflect EPA guidance.

  4. 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....

  5. 76 FR 31342 - Agency Information Collection Activities; Proposed Collection; Comment Request; Current Good...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-31

    ... Collection; Comment Request; Current Good Manufacturing Practice Regulations for Finished Pharmaceuticals... Current Good Manufacturing Practice (CGMP) Regulations for Finished Pharmaceuticals. DATES: Submit either... of information technology. Current Good Manufacturing Practice Regulations for...

  6. 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

  7. Input Enhancement in Instructed SLA: Theoretical Bases.

    ERIC Educational Resources Information Center

    Smith, Michael Sharwood

    1993-01-01

    The concept of input to the language learner is examined with reference to some current theorizing about language processing and the idea of modular systems of knowledge. It is argued that exposure to a second language engages the learner in a whole battery of different processing mechanisms. (21 references) (Author/LB)

  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. Input in Second Language Acquisition.

    ERIC Educational Resources Information Center

    Gass, Susan M., Ed.; Madden, Carolyn G., Ed.

    This collection of conference papers includes: "When Does Teacher Talk Work as Input?"; "Cultural Input in Second Language Learning"; "Skilled Variation in a Kindergarten Teacher's Use of Foreigner Talk"; "Teacher-Pupil Interaction in Second Language Development"; "Foreigner Talk in the University Classroom"; "Input and Interaction in the…

  10. Intensive Input in Language Acquisition.

    ERIC Educational Resources Information Center

    Trimino, Andy; Ferguson, Nancy

    This paper discusses the role of input as one of the universals in second language acquisition theory. Considerations include how language instructors can best organize and present input and when certain kinds of input are more important. A self-administered program evaluation exercise using relevant theoretical and methodological contributions…

  11. High-frequency matrix converter with square wave input

    DOEpatents

    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.

  12. 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.

  13. 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.

  14. 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

  15. Recording Hyperpolarization-Activated Cyclic Nucleotide-Gated Channel Currents (Ih) in Neurons.

    PubMed

    Shah, Mala M

    2016-01-01

    Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are voltage-gated ion channels that play a crucial role in many physiological processes such as memory formation and spatial navigation. Alterations in expression and function of HCN channels have also been associated with multiple disorders including epilepsy, neuropathic pain, and anxiety/depression. Interestingly, neuronal HCN currents (Ih) have diverse biophysical properties in different neurons. This is likely to be in part caused by the heterogeneity of the HCN subunits expressed in neurons. This variation in biophysical characteristics is likely to influence how Ih affects neuronal activity. Thus, it is important to record Ih directly from individual neurons. This protocol describes voltage-clamp methods that can be used to record neuronal Ih under whole-cell voltage-clamp conditions, in cell-attached mode, or with outside-out patches. The information obtained using this approach can be used in combination with other techniques such as computational modeling to determine the significance of Ih for neuronal function. PMID:27371600

  16. 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

  17. 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

  18. 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.

  19. 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

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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

  18. [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.

  19. 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.

  20. 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

  1. 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…

  2. Rotenone enhances N-methyl-D-aspartate currents by activating a tyrosine kinase in rat dopamine neurons.

    PubMed

    Wu, Yan-Na; Martella, Giuseppina; Johnson, Steven W

    2007-11-19

    Our previous work showed that the pesticide rotenone increases the amplitude of inward currents evoked by N-methyl-D-aspartate (NMDA) in substantia nigra dopamine neurons. Using patch pipettes to record whole-cell currents in rat brain slices, we report that the rotenone-induced potentiation of NMDA current is blocked by the tyrosine kinase inhibitors genistein and PP1. This action of rotenone is mimicked by H2O2, which is also blocked by genistein. Our results suggest that the rotenone-dependent increase in NMDA current is mediated by release of reactive oxygen species that activates a protein tyrosine kinase.

  3. A novel large-conductance Ca(2+)-activated potassium channel and current in nerve terminals of the rat neurohypophysis.

    PubMed Central

    Wang, G; Thorn, P; Lemos, J R

    1992-01-01

    1. Nerve terminals of the rat posterior pituitary were acutely dissociated and identified using a combination of morphological and immunohistochemical techniques. Terminal membrane currents were studied using the 'whole-cell' patch clamp technique and channels were studied using inside-out and outside-out patches. 2. In physiological solutions, but with 7 mM 4-aminopyridine (4-AP), depolarizing voltage clamp steps from different holding potentials (-90 or -50 mV) elicited a fast, inward current followed by a slow, sustained, outward current. This outward current did not appear to show any steady-state inactivation. 3. The threshold for activation of the outward current was -30 mV and the current-voltage relation was 'bell-shaped'. The amplitude increased with increasingly depolarized potential steps. The outward current reversal potential was measured using tail current analysis and was consistent with that of a potassium current. 4. The sustained potassium current was determined to be dependent on the concentration of intracellular calcium. Extracellular Cd2+ (80 microM), a calcium channel blocker, also reversibly abolished the outward current. 5. The current was delayed in onset and was sustained over the length of a 150 ms-duration depolarizing pulse. The outward current reached a peak plateau and then decayed slowly. The decay was fitted by a single exponential with a time constant of 9.0 +/- 2.2 s. The decay constants did not show a dependence on voltage but rather on intracellular Ca2+. The time course of recovery from this decay was complex with full recovery taking > 190 s. 6. 4-AP (7 mM), dendrotoxin (100 nM), apamin (40-80 nM), and charybdotoxin (10-100 nM) had no effect on the sustained outward current. In contrast Ba2+ (200 microM) and tetraethylammonium inhibited the current, the latter in a dose-dependent manner (apparent concentration giving 50% of maximal inhibition (IC50) = 0.51 mM). 7. The neurohypophysial terminal outward current recorded here

  4. 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.

  5. Adolescent female C57BL/6 mice with vulnerability to activity-based anorexia exhibit weak inhibitory input onto hippocampal CA1 pyramidal cells

    PubMed Central

    Chowdhury, Tara G.; Wable, Gauri S.; Sabaliauskas, Nicole A.; Aoki, Chiye

    2014-01-01

    Anorexia nervosa (AN) is an eating disorder characterized by self-imposed severe starvation and often linked with excessive exercise. Activity-based anorexia (ABA) is an animal model that reproduces some of the behavioral phenotypes of AN, including the paradoxical increase in voluntary exercise following food restriction (FR). Although certain rodents have been used successfully in this animal model, C57BL/6 mice are reported to be less susceptible to ABA. We re-examined the possibility that female C57BL/6 mice might exhibit ABA vulnerability during adolescence, the developmental stage/sex among the human population with particularly high AN vulnerability. After introducing the running wheel to the cage for three days, ABA was induced by restricting food access to 1 hour per day (ABA1, N=13) or 2 hours per day (ABA2, N=10). All 23 exhibited increased voluntary wheel running (p<0.005) and perturbed circadian rhythm within two days. Only one out of five survived ABA1 for three days, while ten out of ten survived ABA2 for three days and could subsequently restore their body weight and circadian rhythm. Exposure of recovered animals to a second ABA2 induction revealed a large range of vulnerability, even within littermates. To look for the cellular substrate of differences in vulnerability, we began by examining synaptic patterns in the hippocampus, a brain region that regulates anxiety as well as plasticity throughout life. Quantitative EM analysis revealed that CA1 pyramidal cells of animals vulnerable to the second ABA2 exhibit less GABAergic innervation on cell bodies and dendrites, relative to the animals resilient to the second ABA (p<0.001) or controls (p<0.05). These findings reveal that C57BL/6J adolescent females can be used to capture brain changes underlying ABA vulnerability, and that GABAergic innervation of hippocampal pyramidal neurons is one important cellular substrate to consider for understanding the progression of and resilience to AN. PMID

  6. 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

  7. 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.

  8. Visinin-like neuronal calcium sensor proteins regulate the slow calcium-activated afterhyperpolarizing current in the rat cerebral cortex.

    PubMed

    Villalobos, Claudio; Andrade, Rodrigo

    2010-10-27

    Many neurons in the nervous systems express afterhyperpolarizations that are mediated by a slow calcium-activated potassium current. This current shapes neuronal firing and is inhibited by neuromodulators, suggesting an important role in the regulation of neuronal function. Surprisingly, very little is currently known about the molecular basis for this current or how it is gated by calcium. Recently, the neuronal calcium sensor protein hippocalcin was identified as a calcium sensor for the slow afterhyperpolarizing current in the hippocampus. However, while hippocalcin is very strongly expressed in the hippocampus, this protein shows a relatively restricted distribution in the brain. Furthermore, the genetic deletion of this protein only partly reduces the slow hyperpolarizing current in hippocampus. These considerations question whether hippocalcin can be the sole calcium sensor for the slow afterhyperpolarizing current. Here we use loss of function and overexpression strategies to show that hippocalcin functions as a calcium sensor for the slow afterhyperpolarizing current in the cerebral cortex, an area where hippocalcin is expressed at much lower levels than in hippocampus. In addition we show that neurocalcin δ, but not VILIP-2, can also act as a calcium sensor for the slow afterhyperpolarizing current. Finally we show that hippocalcin and neurocalcin δ both increase the calcium sensitivity of the afterhyperpolarizing current but do not alter its sensitivity to inhibition by carbachol acting through the Gαq-11-PLCβ signaling cascade. These results point to a general role for a subgroup of visinin-like neuronal calcium sensor proteins in the activation of the slow calcium-activated afterhyperpolarizing current.

  9. 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

  10. 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

  11. Distinct mechanisms for activation of Cl− and K+ currents by Ca2+ from different sources in mouse sympathetic neurones

    PubMed Central

    Martínez-Pinna, Juan; McLachlan, Elspeth M; Gallego, Roberto

    2000-01-01

    We have investigated the roles of different voltage-dependent Ca2+ channels in the activation of the Cl− and K+ channels responsible for the afterdepolarization (ADP) and slow afterhyperpolarization (AHP) in sympathetic neurones of the isolated mouse superior cervical ganglion in vitro. The ADP and its associated Ca2+-activated Cl− current were markedly decreased by ω-agatoxin IVA (40–200 nm) and nifedipine (1–10 μm), but not by ω-conotoxin GVIA (300 nm). In contrast, the AHP and the apamin-sensitive Ca2+-activated K+ current that underlies this potential were blocked by ω-conotoxin GVIA, but were not affected by ω-agatoxin IVA and were only slightly reduced by nifedipine. Ryanodine (20 μm) reduced the Ca2+-activated Cl− current following an action potential by 75 % but on average did not affect the Ca2+-activated K+ current. Evidence that R-type channels provide a proportion of the Ca2+ activating both types of Ca2+-dependent channel was obtained. We conclude that Ca2+ entering through L- and P-type Ca2+ channels preferentially activates the Cl− current responsible for the ADP in mouse sympathetic neurones, predominantly via Ca2+-induced Ca2+ release, whereas the Ca2+ that activates the K+ channels responsible for the AHP enters predominantly through N-type channels. The data can be explained by the selective association of each type of Ca2+ channel with particular intracellular mechanisms for activating other membrane channels, one indirect and the other direct, probably located at discrete sites on the soma and dendrites. PMID:10970427

  12. 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.

  13. From Input to Output: Communication-Based Teaching Techniques.

    ERIC Educational Resources Information Center

    Tschirner, Erwin

    1992-01-01

    Communication-based teaching techniques are described that lead German language students from input to output in a stimulating and motivating learning environment. Input activities are most useful for presenting speech acts, vocabulary, and grammar; output activities, for fine-tuning those areas as well as for expanding students' productive…

  14. 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.

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  19. 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

  20. 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

  1. 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.

  2. 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

  3. Secreted CLCA1 modulates TMEM16A to activate Ca(2+)-dependent chloride currents in human cells.

    PubMed

    Sala-Rabanal, Monica; Yurtsever, Zeynep; Nichols, Colin G; Brett, Tom J

    2015-03-17

    Calcium-activated chloride channel regulator 1 (CLCA1) activates calcium-dependent chloride currents; neither the target, nor mechanism, is known. We demonstrate that secreted CLCA1 activates calcium-dependent chloride currents in HEK293T cells in a paracrine fashion, and endogenous TMEM16A/Anoctamin1 conducts the currents. Exposure to exogenous CLCA1 increases cell surface levels of TMEM16A and cellular binding experiments indicate CLCA1 engages TMEM16A on the surface of these cells. Altogether, our data suggest that CLCA1 stabilizes TMEM16A on the cell surface, thus increasing surface expression, which results in increased calcium-dependent chloride currents. Our results identify the first Cl(-) channel target of the CLCA family of proteins and establish CLCA1 as the first secreted direct modifier of TMEM16A activity, delineating a unique mechanism to increase currents. These results suggest cooperative roles for CLCA and TMEM16 proteins in influencing the physiology of multiple tissues, and the pathology of multiple diseases, including asthma, COPD, cystic fibrosis, and certain cancers.

  4. cGMP activates a pH-sensitive leak K+ current in the presumed cholinergic neuron of basal forebrain.

    PubMed

    Toyoda, Hiroki; Saito, Mitsuru; Sato, Hajime; Dempo, Yoshie; Ohashi, Atsuko; Hirai, Toshihiro; Maeda, Yoshinobu; Kaneko, Takeshi; Kang, Youngnam

    2008-05-01

    In an earlier study, we demonstrated that nitric oxide (NO) causes the long-lasting membrane hyperpolarization in the presumed basal forebrain cholinergic (BFC) neurons by cGMP-PKG-dependent activation of leak K+ currents in slice preparations. In the present study, we investigated the ionic mechanisms underlying the long-lasting membrane hyperpolarization with special interest in the pH sensitivity because 8-Br-cGMP-induced K+ current displayed Goldman-Hodgkin-Katz rectification characteristic of TWIK-related acid-sensitive K+ (TASK) channels. When examined with the ramp command pulse depolarizing from -130 to -40 mV, the presumed BFC neurons displayed a pH-sensitive leak K+ current that was larger in response to pH decrease from 8.3 to 7.3 than in response to pH decrease from 7.3 to 6.3. This K+ current was similar to TASK1 current in its pH sensitivity, whereas it was highly sensitive to Ba(2+), unlike TASK1 current. The 8-Br-cGMP-induced K+ currents in the presumed BFC neurons were almost completely inhibited by lowering external pH to 6.3 as well as by bath application of 100 microM Ba(2+), consistent with the nature of the leak K+ current expressed in the presumed BFC neurons. After 8-Br-cGMP application, the K+ current obtained by pH decrease from 7.3 to 6.3 was larger than that obtained by pH decrease from pH 8.3 to 7.3, contrary to the case seen in the control condition. These observations strongly suggest that 8-Br-cGMP activates a pH- and Ba(2+)-sensitive leak K+ current expressed in the presumed BFC neurons by modulating its pH sensitivity.

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  10. 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

  11. Quisqualate-activated single channel currents in neuromuscular preparations of small and large crayfish.

    PubMed

    Finger, W; Martin, C; Pareto, A

    1988-06-01

    Single channel currents elicited by 1-5 mumol/l quisqualate in neuromuscular preparations in large (greater than 16 month old) and small (1-3 month old) crayfish were recorded by means of the patch-clamp technique. In preparations from large crayfish single channel currents of variable amplitude (-1 to -12 pA) were induced by quisqualate. The mean burst lengths of these currents were tau approximately equal to 1-2 ms. In the opener muscle of the first walking leg and the contractor epimeralis muscle of small crayfish the mean burst lengths of single channel currents evoked by quisqualate were prolonged by a factor of about 4 (tau approximately equal to 5 ms). Moreover, in the opener muscle of the first walking leg of small crayfish single channel currents of small amplitude (-0.5 to -2.5 pA) were preferentially evoked by quisqualate. By contrast, in the contractor epimeralis muscle of small crayfish mainly single channel currents of large amplitude (-10 to -12 pA) were elicited by quisqualate. The results suggest that at the stage of neuromuscular development characterizing the small crayfish, gating properties of excitatory postsynaptic channels are different from those in adult crayfish. Furthermore, the results obtained in the opener muscle of the first walking leg of small crayfish are consistent with those obtained previously by means of the noise analysis technique.

  12. 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…

  13. From Nose to Brain: Un-Sensed Electrical Currents Applied in the Nose Alter Activity in Deep Brain Structures

    PubMed Central

    Weiss, Tali; Shushan, Sagit; Ravia, Aharon; Hahamy, Avital; Secundo, Lavi; Weissbrod, Aharon; Ben-Yakov, Aya; Holtzman, Yael; Cohen-Atsmoni, Smadar; Roth, Yehudah; Sobel, Noam

    2016-01-01

    Rules linking patterns of olfactory receptor neuron activation in the nose to activity patterns in the brain and ensuing odor perception remain poorly understood. Artificially stimulating olfactory neurons with electrical currents and measuring ensuing perception may uncover these rules. We therefore inserted an electrode into the nose of 50 human volunteers and applied various currents for about an hour in each case. This induced assorted non-olfactory sensations but never once the perception of odor. To validate contact with the olfactory path, we used functional magnetic resonance imaging to measure resting-state brain activity in 18 subjects before and after un-sensed stimulation. We observed stimulation-induced neural decorrelation specifically in primary olfactory cortex, implying contact with the olfactory path. These results suggest that indiscriminate olfactory activation does not equate with odor perception. Moreover, this effort serendipitously uncovered a novel path for minimally invasive brain stimulation through the nose. PMID:27591145

  14. 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

  15. Glycinergic synaptic inputs to bipolar cells in the salamander retina

    PubMed Central

    Maple, Bruce R; Wu, Samuel M

    1998-01-01

    Glycine activated strychnine-sensitive chloride conductances at both the dendrites and the axonal telodendria of most bipolar cells in the salamander retina. The chloride equilibrium potential of bipolar cells was found to be negative to -50 mV, indicating that glycinergic synapses on bipolar cells are inhibitory. Some bipolar cells exhibited discrete, strychnine-sensitive, chloride-mediated inhibitory postsynaptic currents (IPSCs). These were elicited by focal application of glutamate at the inner plexiform layer (IPL). Glycinergic synapses were localized using simultaneous focal application of calcium to retinal slices bathed in calcium-free media. Both dendritic and telodendritic glycinergic IPSCs were observed. The decay of the telodendritic IPSCs was well fitted by a single exponential with a time constant of 17.7 ± 8.7 ms. Similar kinetics were observed for dendritic IPSCs in some cells, but in one class of on-centre bipolar cell the decay of the dendritic IPSCs was better fitted by a sum of two exponentials with time constants 9.9 ± 4.3 and 51.3 ± 24.3 ms. The dendritic IPSCs were best driven by application of glutamate at the distal IPL (the off sublamina), while the telodendritic IPSCs were driven best by application near the telodendria. These results suggest that bipolar cell dendrites receive inhibitory glycinergic inputs from interplexiform cells that are excited by off-centre bipolar cells, whereas bipolar cell telodendria receive glycinergic amacrine cell inputs that are antagonistic to the photoreceptor inputs. Both inputs could be elicited in the presence of tetrodotoxin (TTX), but the dendritic IPSCs were sometimes abolished by TTX, suggesting that sodium-dependent spikes play an important role in the transmission of interplexiform cell signals to the outer plexiform layer. PMID:9503334

  16. 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.

  17. 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

  18. Hypoxia Modulates the Swelling-Activated Cl Current in Human Glioblastoma Cells: Role in Volume Regulation and Cell Survival.

    PubMed

    Sforna, Luigi; Cenciarini, Marta; Belia, Silvia; Michelucci, Antonio; Pessia, Mauro; Franciolini, Fabio; Catacuzzeno, Luigi

    2017-01-01

    The malignancy of glioblastoma multiforme (GBM), the most common human brain tumor, correlates with the presence of hypoxic areas, but the underlying mechanisms are unclear. GBM cells express abundant Cl channels whose activity supports cell volume and membrane potential changes, ultimately leading to cell proliferation, migration, and escaping death. In non-tumor tissues Cl channels are modulated by hypoxia, which prompted us to verify whether hypoxia would also modulate Cl channels in GBM cells. Our results show that in GBM cell lines, acute application of a hypoxic solution activates a Cl current displaying the biophysical and pharmacological features of the swelling-activated Cl current (ICl,swell ). We also found that acute hypoxia increased the cell volume by about 20%, and a 30% hypertonic solution partially inhibited the hypoxia-activated Cl current, suggesting that cell swelling and the activation of the Cl current are sequential events. Notably, the hypoxia-induced cell swelling was followed by a regulatory volume decrease (RVD) mediated mainly by ICl,swell . Since, a hypoxia-induced prolonged cell swelling is usually regarded as a death insult, we hypothesized that the hypoxia-activated Cl current could limit cell swelling and prevent necrotic death of GBM cells under hypoxic conditions. In accordance, we found that the ICl,swell inhibitor DCPIB hampered the RVD process, and more importantly it sensibly increased the hypoxia-induced necrotic death in these cells. Taken together, these results suggest that Cl channels are strongly involved in the survival of GBM cells in a hypoxic environment, and may thus represent a new therapeutic target for this malignant tumor. J. Cell. Physiol. 232: 91-100, 2017. © 2016 Wiley Periodicals, Inc.

  19. Properties of a novel K+ current that is active at resting potential in rabbit pulmonary artery smooth muscle cells.

    PubMed Central

    Evans, A M; Osipenko, O N; Gurney, A M

    1996-01-01

    1. An outward current (IK(N)) was identified in rabbit pulmonary artery myocytes, which persisted after Ca(2+)-activated and ATP-sensitive K+ currents were blocked by TEA (10 mM) and glibenclamide (10 microM), respectively, and after A-like (IK(A)) and delayed rectifer (IK(V)) K+ currents were inactivated by clamping the cell at 0 mV for 10 min. It was found in smooth muscle cells at all levels of the pulmonary arterial tree. 2. The relationship between the reversal potential of IK(N) and the extracellular K+ concentration ([K+]o) was close to that expected for a K(+)-selective channel. Deviation from Nernstian behaviour at low [K+)o could be accounted for by the presence of an accompanying leakage current. 3. IK(N) is voltage gated. It has a low threshold for activation, between -80 and -65 mV, and activates slowly without delay. Activation follows an exponential time course with a time constant of 1.6 s at -60 mV. Deactivation is an order of magnitude faster than activation, with a time constant of 107 ms at -60 mV. 4. IK(N) showed a similar sensitivity to 4-aminopyridine as IK(A) and IK(V), with 49% inhibition at 10 mM. The current was not blocked by microM quinine, which did inhibit IK(A) and IK(V), by 51 and 47%, respectively. 5. Activation of IK(N) was detected at potentials close to the resting membrane potential of pulmonary artery smooth muscle cells, under physiological conditions. Thus it is likely to contribute to the resting membrane potential of these cells. PMID:8910225

  20. Role of high-voltage activated potassium currents in high-frequency neuronal firing: evidence from a basal metazoan.

    PubMed

    Buckingham, Steven D; Spencer, Andrew N

    2002-08-01

    Certain neurons of vertebrates are specialized for high-frequency firing. Interestingly, high-frequency firing is also seen in central neurons in basal bilateral metazoans. Recently, the role of potassium currents with rightward-shifted activation curves in producing high-frequency firing has come under scrutiny. We apply intracellular recording, patch-clamp techniques, and compartmental modeling to examine the roles of rightward-shifted potassium currents in repetitive firing and shaping of action potentials in central neurons of the flatworm, Notoplana atomata (Phylum Platyhelminthes). The kinetic properties of potassium and sodium currents were determined from patch-clamp experiments on dissociated brain cells. To predict the effects of changing the steady-state and kinetic properties of these potassium currents, these data were incorporated into a computer model of a 30-microm spherical cell with the levels of current adjusted to approximate the values recorded in voltage-clamp experiments. The model was able to support regenerative spikes at high frequencies in response to injected current. Current-clamp recordings of cultured cells and of neurons in situ also showed evidence of very-high-frequency firing. Adjusting the ratio of inactivating to non-inactivating potassium currents had little effect upon the firing pattern of the cell or its ability to fire at high frequencies, whereas the presence of the non-inactivating current was necessary for repetitive firing. Computer simulations suggested that the rightward shift in voltage sensitivity confers a raised firing threshold, while rapid channel kinetics underlie high frequency firing, and the large activation range enhances the coding range of the cell.

  1. 75 FR 9593 - Agency Information Collection Activities; Proposed Renewal of Several Currently Approved...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-03

    ... manufacturing pesticide chemicals, wholesale merchandising of pesticide products, or pest management activities... pesticidal devices to protect children and adults from serious illness or injury resulting from...

  2. Current induced Optical Activity in Topological Insulator Bi2Te2Se1

    NASA Astrophysics Data System (ADS)

    Mandal, Nirajan; Mitkowski, Irek; Glazov, Mikhail; Chen, Yong

    Current induced polarization rotation of light (provided by a laser with wavelength =635nm) was studied from topological insulator (TI), Bi2Te2Se1, grown by Bridgman method. The magnitude of the observed response increases linearly with the applied current and reverses sign upon reversing the current direction. Possible origins of the rotation can include the linear electro-optic Pockels effect (linear birefringence) and spin-Kerr effect due to the current induced spin polarization (e.g, resulting from the spin momentum locking of the surface states) at the sample surface. At room temperature, the rotation was measured as a function of the angle of incidence and laser polarization. Dependence of the rotation angle on the polarization of light (S or P) was used to isolate contributions from these two effects. The contribution from the electro optic effect was found to dominate over that from the current-induced spin- Kerr effect. Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907.

  3. Activity-dependent modulation of the presynaptic potassium current in the frog neuromuscular junction.

    PubMed Central

    Miralles, F; Solsona, C

    1996-01-01

    1. Changes in the electrical properties of frog motor nerve endings caused by the invasion of an action potential were studied by the perineural recording technique. Two equal supramaximal stimuli separated by a variable time interval were applied to the nerve trunk. The latency and amplitude of the deflections associated with the nodal Na+ current and presynaptic K+ current elicited by the second pulse were compared with control currents. 2. The deflection associated with the presynaptic K+ current elicited in response to the second stimulus was absent at the shortest interstimulus interval and showed a progressive increase in its amplitude as the interstimulus interval was lengthened, reaching values greater than control in most terminals. During the same period the nodal Na+ current did not change. 3. The experimental results were compared with a computer model of the distal axonal segment and its terminal. Response of the model to twin-pulse stimulation was in marked disagreement with the experimental results unless an inactivating K+ channel, with properties derived ad hoc, was incorporated into the simulation. 4. These results suggest that in the first 6-7 ms after a nerve impulse has invaded a frog motor nerve ending, maximal K+ conductance remains below the value at rest due to the fast inactivation of a K+ conductance. Following this, there is a period in which K+ conductance is greater than control values although the basis for this is unknown. PMID:8887778

  4. 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

  5. Input impedance of microstrip antennas

    NASA Technical Reports Server (NTRS)

    Deshpande, M. D.; Bailey, M. C.

    1982-01-01

    Using Richmond's reaction integral equation, an expression is derived for the input impedance of microstrip patch antennas excited by either a microstrip line or a coaxial probe. The effects of the finite substrate thickness, a dielectric protective cover, and associated surface waves are properly included by the use of the exact dyadic Green's function. Using the present formulation the input impedance of a rectangular microstrip antenna is determined and compared with experimental and earlier calculated results.

  6. 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.

  7. 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

  8. Are the physical activity parenting practices reported by U.S. and Canadian parents captured in currently published instruments?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The purpose of this study was to compare the physical activity parenting practices (PAPPs) parents report using with the PAPPs incorporated in the published literature. PAPPs in the literature were identified by reviewing the content of 74 published PAPPs measures obtained from current systematic re...

  9. The Rhodes Scholarship in the Current Era of Student Activism: What Do We Consider "Prestigious" and Who Benefits?

    ERIC Educational Resources Information Center

    Adam, LeAnn

    2016-01-01

    Contemporary student activism has revealed deep feelings of alienation on college campuses, prompting strong reactions to current and historical racial injustice, including the history of Cecil Rhodes. Can advisors promote restorative justice by encouraging reflection upon privileges afforded to Rhodes scholars and their responsibility to address…

  10. 75 FR 65499 - Agency Information Collection Activities: Form I-600/I-600A, Extension of a Currently Approved...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-25

    ... published in the Federal Register on June 23, 2010, at 75 FR 35824, allowing for a 60-day public comment... SECURITY U.S. Citizenship and Immigration Services Agency Information Collection Activities: Form I-600/ I-600A, Extension of a Currently Approved Information Collection; Comment Request ACTION: 30-Day...

  11. 75 FR 35824 - Agency Information Collection Activities: Forms I-600/I-600A, Extension of a Currently Approved...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-23

    ... SECURITY U.S. Citizenship and Immigration Services Agency Information Collection Activities: Forms I-600/I-600A, Extension of a Currently Approved Information Collection; Comment Request ACTION: 60-Day Notice of Information Collection Under Review: Forms I- 600/I-600A, Petition To Classify Orphan as...

  12. 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)

  13. Active electron energy distribution function control in direct current discharge using an auxiliary electrode

    SciTech Connect

    Schweigert, I. V.; Kaganovich, I. D.; Demidov, V. I.

    2013-10-15

    The electron energy distribution functions are studied in the low voltage dc discharge with a constriction, which is a diaphragm with an opening. The dc discharge glows in helium and is sustained by the electron current emitted from a heated cathode. We performed kinetic simulations of dc discharge characteristics and electron energy distribution functions for different gas pressures (0.8 Torr-4 Torr) and discharge current of 0.1 A. The results of these simulations indicate the ability to control the shape of the electron energy distribution functions by variation of the diaphragm opening radius.

  14. 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…

  15. EPRAT-ExoPlanetary Roadmap Advisory Team-ESA's Current Exoplanetary Activities

    NASA Astrophysics Data System (ADS)

    Fridlund, Malcolm

    2009-08-01

    The European Space Agency has initiated the preparation of a roadmap in order to fulfill scientific goals of the Cosmic Vision scientific plan with respect to exoplanets and especially terrestrial bodies orbiting stars other than our Sun. The activity is intended to be finished in June 2010. In this paper we report initial considerations and give a timeline for the activity.

  16. 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....

  17. 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.

  18. 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... of type A medicated articles. DATES: Submit either electronic or written comments on the collection... Type A Medicated Articles--21 CFR Part 226 (OMB Control Number 0910-0154)--Extension Under section...

  19. 77 FR 33760 - Agency Information Collection Activities: Form G-646, Extension of a Currently Approved...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-07

    ... collection was previously published in the Federal Register on March 9, 2012, at 77 FR 14407, allowing for a... Information Collection Under Review: Form G- 646, Sworn Statement of Refugee Applying for Admission to the... currently approved information collection. (2) Title of the Form/Collection: Sworn Statement of...

  20. 76 FR 20362 - Agency Information Collection Activities: Form I-905, Extension of a Currently Approved...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-12

    ..., Extension of a Currently Approved Information Collection; Comment Request Action: 60-Day Notice of... Health Care Workers; OMB Control No. 1615-0086. The Department of Homeland Security, U.S. Citizenship and... sixty days until June 13, 2011. During this 60 day period, USCIS will be evaluating whether to...

  1. 75 FR 41214 - Agency Information Collection Activities: Extension of a Currently Approved Information...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-15

    ... be requested via email to: forms.ice@dhs.gov with ``ICE Form G-146'' in the subject line. Dated: July... Information Collection for Review; Form G-146, Nonimmigrant Checkout Letter; OMB Control No. 1653-0020. The...: Extension of a currently approved Information Collection. (2) Title of the Form/Collection:...

  2. 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

  3. 75 FR 44841 - Agency Information Collection Activities; Revision of a Currently-Approved Information Collection...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-29

    ... Currently-Approved Information Collection Request: Transportation of Household Goods; Consumer Protection..., 2010, concerning an information collection request (ICR), ``Transportation of Household Goods; Consumer... household goods movers'' to read: Respondents: 8,500 [6,000 household goods movers + 2,500...

  4. Current Status of Physical Education, Sport and Active Recreation. Documentary Statement.

    ERIC Educational Resources Information Center

    Holbrook, Leona

    This documentary statement was prepared in response to those members participating in the 18th International Congress of the International Council for Health, Physical Education, and Recreation, who recommended in August 1975 that member countries prepare a statement on current status of health, physical education and recreation. Attention is…

  5. 75 FR 22843 - Agency Information Collection Activities: Revision of a Currently Approved Collection; Comments...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-30

    ... evidence. The information will provide statistics on laboratories' capacity to analyze forensic crime... Currently Approved Collection 2009 Census of Publicly Funded Forensic Crime Laboratories. The Department of... and assumptions used; (3) Enhance the quality, utility, and clarity of the information to be...

  6. 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.

  7. Activity-based proteomics probes for carbohydrate-processing enzymes: current trends and future outlook.

    PubMed

    Stubbs, Keith A

    2014-05-22

    Carbohydrate-processing enzymes are gaining more attention due to their roles in health and disease as these enzymes are involved in the construction and deconstruction of vast arrays of glycan structures. As a result, the development of methods to identify these enzymes in complex biological systems is of increasing interest. Activity-based proteomics probes (ABPPs) are increasingly being used in glycobiology to detect and identify functionally related proteins (and homologues) within a biological system. This review will describe the design of activity-based proteomics probes, provide examples of compounds that have been used to profile activity in the area of carbohydrate-processing enzymes, and give some future perspectives.

  8. Impact of basal forebrain cholinergic inputs on basolateral amygdala neurons.

    PubMed

    Unal, Cagri T; Pare, Denis; Zaborszky, Laszlo

    2015-01-14

    In addition to innervating the cerebral cortex, basal forebrain cholinergic (BFc) neurons send a dense projection to the basolateral nucleus of the amygdala (BLA). In this study, we investigated the effect of near physiological acetylcholine release on BLA neurons using optogenetic tools and in vitro patch-clamp recordings. Adult transgenic mice expressing cre-recombinase under the choline acetyltransferase promoter were used to selectively transduce BFc neurons with channelrhodopsin-2 and a reporter through the injection of an adeno-associated virus. Light-induced stimulation of BFc axons produced different effects depending on the BLA cell type. In late-firing interneurons, BFc inputs elicited fast nicotinic EPSPs. In contrast, no response could be detected in fast-spiking interneurons. In principal BLA neurons, two different effects were elicited depending on their activity level. When principal BLA neurons were quiescent or made to fire at low rates by depolarizing current injection, light-induced activation of BFc axons elicited muscarinic IPSPs. In contrast, with stronger depolarizing currents, eliciting firing above ∼ 6-8 Hz, these muscarinic IPSPs lost their efficacy because stimulation of BFc inputs prolonged current-evoked afterdepolarizations. All the effects observed in principal neurons were dependent on muscarinic receptors type 1, engaging different intracellular mechanisms in a state-dependent manner. Overall, our results suggest that acetylcholine enhances the signal-to-noise ratio in principal BLA neurons. Moreover, the cholinergic engagement of afterdepolarizations may contribute to the formation of stimulus associations during fear-conditioning tasks where the timing of conditioned and unconditioned stimuli is not optimal for the induction of synaptic plasticity.

  9. 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...

  10. 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.

  11. 78 FR 17282 - Agency Information Collection Activities; Approval of a Currently Approved Information Collection...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-20

    ...), DOT. ACTION: Notice; correction. SUMMARY: The Federal Motor Carrier Safety Administration published a... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Federal Motor Carrier Safety Administration Agency Information Collection Activities; Approval of...

  12. 77 FR 37063 - Agency Information Collection Activities: Extension, Without Change, of a Currently Approved...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-20

    ... SECURITY United States Immigration and Customs Enforcement Agency Information Collection Activities...-0026). The Department of Homeland Security, U.S. Immigration and Customs Enforcement (ICE), will submit the following information collection request for review and clearance in accordance with the...

  13. Current perspectives on physical activity and exercise for youth with diabetes.

    PubMed

    Pivovarov, Jacklyn A; Taplin, Craig E; Riddell, Michael C

    2015-06-01

    Regular physical activity (PA) for youth with diabetes improves cardiorespiratory fitness, body composition, bone health, insulin sensitivity, and psychosocial well-being. However many youth with diabetes or pre-diabetes fail to meet minimum PA guidelines and a large percentage of youth with diabetes are overweight or obese. Active youth with type 1 diabetes tend to have lower HbA1c levels and reduced insulin needs, whereas activity in adolescents at-risk for type 2 diabetes improves various measures of metabolism and body composition. Insulin and nutrient adjustments for exercise in type 1 diabetes is complex because of varied responses to exercise type and because of the different times of day that exercise is performed. This review highlights the benefits of exercise and the established barriers to exercise participation in the pediatric diabetes population. A new exercise management algorithm for insulin and carbohydrate intake strategies for active youth with type 1 diabetes is presented.

  14. 77 FR 71018 - Agency Information Collection Activities; Extension of a Currently Approved Collection; Comment...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-28

    ... Office of Juvenile Justice and Delinquency Prevention Agency Information Collection Activities; Extension... Juvenile Justice and Delinquency Prevention, Office of Justice Programs, Department of Justice. ACTION: 30... the collection: The Office of Juvenile Justice and Delinquency Prevention, Office of Justice...

  15. 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

    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

  16. 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

  17. Adenosine inhibits glutamatergic input to basal forebrain cholinergic neurons

    PubMed Central

    Hawryluk, J. M.; Ferrari, L. L.; Keating, S. A.

    2012-01-01

    Adenosine has been proposed as an endogenous homeostatic sleep factor that accumulates during waking and inhibits wake-active neurons to promote sleep. It has been specifically hypothesized that adenosine decreases wakefulness and promotes sleep recovery by directly inhibiting wake-active neurons of the basal forebrain (BF), particularly BF cholinergic neurons. We previously showed that adenosine directly inhibits BF cholinergic neurons. Here, we investigated 1) how adenosine modulates glutamatergic input to BF cholinergic neurons and 2) how adenosine uptake and adenosine metabolism are involved in regulating extracellular levels of adenosine. Our experiments were conducted using whole cell patch-clamp recordings in mouse brain slices. We found that in BF cholinergic neurons, adenosine reduced the amplitude of AMPA-mediated evoked glutamatergic excitatory postsynaptic currents (EPSCs) and decreased the frequency of spontaneous and miniature EPSCs through presynaptic A1 receptors. Thus we have demonstrated that in addition to directly inhibiting BF cholinergic neurons, adenosine depresses excitatory inputs to these neurons. It is therefore possible that both direct and indirect inhibition may synergistically contribute to the sleep-promoting effects of adenosine in the BF. We also found that blocking the influx of adenosine through the equilibrative nucleoside transporters or inhibiting adenosine kinase and adenosine deaminase increased endogenous adenosine inhibitory tone, suggesting a possible mechanism through which adenosine extracellular levels in the basal forebrain are regulated. PMID:22357797

  18. Short-term desensitization of G-protein-activated, inwardly rectifying K+ (GIRK) currents in pyramidal neurons of rat neocortex.

    PubMed

    Sickmann, Thomas; Alzheimer, Christian

    2003-10-01

    Whole cell recordings from acutely isolated rat neocortical pyramidal cells were performed to study the kinetics and the mechanisms of short-term desensitization of G-protein-activated, inwardly rectifying K+ (GIRK) currents during prolonged application (5 min) of baclofen, adenosine, or serotonin. Most commonly, desensitization of GIRK currents was characterized by a biphasic time course with average time constants for fast and slow desensitization in the range of 8 and 120 s, respectively. The time constants were independent of the agonist used to evoke the current. The biphasic time course was preserved in perforated-patch recordings, indicating that neither component of desensitization is attributable to cell dialysis. Desensitization of GIRK currents displayed a strong heterologous component in that application of a second agonist substantially reduced the responsiveness to a test agonist. Fast desensitization, but not slow desensitization, was lost in cells loaded with GDP, suggesting that the hydrolysis cycle of G proteins might underlie the initial, rapid current decline. Hydrolysis of phosphatidylinositol biphosphate is an unlikely candidate underlying short-term desensitization, because both components of desensitization were preserved in the presence of the phospholipase C inhibitor U73122. We conclude that short-term desensitization does neither result from receptor downregulation nor from altered channel gating but might involve modifications of the G-protein-dependent pathway that serves to translate receptor activation into channel opening.

  19. Anatomical Organization of Multiple Modulatory Inputs in a Rhythmic Motor System.

    PubMed

    Swallie, Shanna E; Monti, Alexis M; Blitz, Dawn M

    2015-01-01

    In rhythmic motor systems, descending projection neuron inputs elicit distinct outputs from their target central pattern generator (CPG) circuits. Projection neuron activity is regulated by sensory inputs and inputs from other regions of the nervous system, relaying information about the current status of an organism. To gain insight into the organization of multiple inputs targeting a projection neuron, we used the identified neuron MCN1 in the stomatogastric nervous system of the crab, Cancer borealis. MCN1 originates in the commissural ganglion and projects to the stomatogastric ganglion (STG). MCN1 activity is differentially regulated by multiple inputs including neuroendocrine (POC) and proprioceptive (GPR) neurons, to elicit distinct outputs from CPG circuits in the STG. We asked whether these defined inputs are compact and spatially segregated or dispersed and overlapping relative to their target projection neuron. Immunocytochemical labeling, intracellular dye injection and three-dimensional (3D) confocal microscopy revealed overlap of MCN1 neurites and POC and GPR terminals. The POC neuron terminals form a defined neuroendocrine organ (anterior commissural organ: ACO) that utilizes peptidergic paracrine signaling to act on MCN1. The MCN1 arborization consistently coincided with the ACO structure, despite morphological variation between preparations. Contrary to a previous 2D study, our 3D analysis revealed that GPR axons did not terminate in a compact bundle, but arborized more extensively near MCN1, arguing against sparse connectivity of GPR onto MCN1. Consistent innervation patterns suggest that integration of the sensory GPR and peptidergic POC inputs occur through more distributed and more tightly constrained anatomical interactions with their common modulatory projection neuron target than anticipated. PMID:26566032

  20. Anatomical Organization of Multiple Modulatory Inputs in a Rhythmic Motor System

    PubMed Central

    Swallie, Shanna E.; Monti, Alexis M.; Blitz, Dawn M.

    2015-01-01

    In rhythmic motor systems, descending projection neuron inputs elicit distinct outputs from their target central pattern generator (CPG) circuits. Projection neuron activity is regulated by sensory inputs and inputs from other regions of the nervous system, relaying information about the current status of an organism. To gain insight into the organization of multiple inputs targeting a projection neuron, we used the identified neuron MCN1 in the stomatogastric nervous system of the crab, Cancer borealis. MCN1 originates in the commissural ganglion and projects to the stomatogastric ganglion (STG). MCN1 activity is differentially regulated by multiple inputs including neuroendocrine (POC) and proprioceptive (GPR) neurons, to elicit distinct outputs from CPG circuits in the STG. We asked whether these defined inputs are compact and spatially segregated or dispersed and overlapping relative to their target projection neuron. Immunocytochemical labeling, intracellular dye injection and three-dimensional (3D) confocal microscopy revealed overlap of MCN1 neurites and POC and GPR terminals. The POC neuron terminals form a defined neuroendocrine organ (anterior commissural organ: ACO) that utilizes peptidergic paracrine signaling to act on MCN1. The MCN1 arborization consistently coincided with the ACO structure, despite morphological variation between preparations. Contrary to a previous 2D study, our 3D analysis revealed that GPR axons did not terminate in a compact bundle, but arborized more extensively near MCN1, arguing against sparse connectivity of GPR onto MCN1. Consistent innervation patterns suggest that integration of the sensory GPR and peptidergic POC inputs occur through more distributed and more tightly constrained anatomical interactions with their common modulatory projection neuron target than anticipated. PMID:26566032