An optimization approach for online identification of harmonic resonance due to pending Volt/VAr operation

Science.gov (United States)

McBee, Kerry D.

The emphasis on creating a more efficient distribution system has led many utility companies to employ dynamic voltage and VAr compensation (Volt/VAr) applications that reduce energy demand, generation, and losses associated with the transmission and distribution of energy. To achieve these benefits, Volt/VAr applications rely upon algorithms to control voltage support equipment, such as transformer load tap changers, voltage regulators, and capacitor banks. The majority of these algorithms utilize metaheuristic programming methods to determine the Volt/VAr scheme that produces the most energy efficient operating conditions. It has been well documented that the interaction between capacitor bank reactance and the inductive reactance of a distribution system can produce parallel harmonic resonance that can damage utility and customer equipment. The Volt/VAr controlling algorithms that account for harmonics do so in an indirect manner that can mask harmonic resonance conditions. Unlike previous research endeavors, the primary focus of the method described within this dissertation is to identify Volt/VAr schemes that prevent harmonic resonance due to capacitor bank operation. Instead of a metaheuristic approach, the harmonic resonance identification algorithm relies upon constrained mixed integer nonlinear programming (MINLP), which is more suited for analyzing impedance characteristics created by the energized states of a system of capacitor banks. Utilizing a numerical approach improves the accuracy of identifying harmonic resonance conditions, while also reducing the complexity of the process by exclusively relying upon the system's admittance characteristics. The novel harmonic resonance identification method is applicable to distribution systems that are dynamically reconfigured, which can result in a number of unknown harmonic resonance producing conditions, a feature unavailable with existing controlling algorithms. The ability to identify all harmonic

Tähenduslik vorm ja esteetiline emotsioon : formalism analüütilises perspektiivis / Marek Volt

Index Scriptorium Estoniae

Volt, Marek

2004-01-01

Inglise kunstikriitiku Clive Belli (1881-1964) seisukohtadest raamatus "Kunst", mida peetakse formalismi teoreetiliseks õigustuseks. Ilmunud ka raamatus: Volt, Marek. Esteetikast. Tallinn : Sirp, 2006

Series-parallel method of direct solar array regulation

Science.gov (United States)

Gooder, S. T.

1976-01-01

A 40 watt experimental solar array was directly regulated by shorting out appropriate combinations of series and parallel segments of a solar array. Regulation switches were employed to control the array at various set-point voltages between 25 and 40 volts. Regulation to within + or - 0.5 volt was obtained over a range of solar array temperatures and illumination levels as an active load was varied from open circuit to maximum available power. A fourfold reduction in regulation switch power dissipation was achieved with series-parallel regulation as compared to the usual series-only switching for direct solar array regulation.

Object Detection: Current and Future Directions

Directory of Open Access Journals (Sweden)

Rodrigo eVerschae

2015-11-01

Full Text Available Object detection is a key ability required by most computer and robot vision systems. The latest research on this area has been making great progress in many directions. In the current manuscript we give an overview of past research on object detection, outline the current main research directions, and discuss open problems and possible future directions.

Particle physicist's dreams about PetaelectronVolt laser plasma accelerators

International Nuclear Information System (INIS)

Vesztergombi, G.

2012-01-01

Present day accelerators are working well in the multi TeV energy scale and one is expecting exciting results in the coming years. Conventional technologies, however, can offer only incremental (factor 2 or 3) increase in beam energies which does not follow the usual speed of progress in the frontiers of high energy physics. Laser plasma accelerators theoretically provide unique possibilities to achieve orders of magnitude increases entering the PetaelectronVolt (PeV) energy range. It will be discussed what kind of new perspectives could be opened for the physics at this new energy scale. What type of accelerators would be required?.

Virtualized Networks and Virtualized Optical Line Terminal (vOLT)

Science.gov (United States)

Ma, Jonathan; Israel, Stephen

2017-03-01

The success of the Internet and the proliferation of the Internet of Things (IoT) devices is forcing telecommunications carriers to re-architecture a central office as a datacenter (CORD) so as to bring the datacenter economics and cloud agility to a central office (CO). The Open Network Operating System (ONOS) is the first open-source software-defined network (SDN) operating system which is capable of managing and controlling network, computing, and storage resources to support CORD infrastructure and network virtualization. The virtualized Optical Line Termination (vOLT) is one of the key components in such virtualized networks.

A three-port direct current converter

DEFF Research Database (Denmark)

2016-01-01

circuit comprises a connection between the at least one input direct current source and the at least one storage battery, the primary side circuit configured for operating as a buck converter; a second magnetic component serially coupled to the first single magnetic component, wherein the first and second...... magnetic components are configured to perform a voltage step-up, wherein the secondary side circuit comprises a connection between the at least one storage battery and at least one load, the secondary side configured for operating as a tapped boost converter; wherein the three-port direct current converter......The three-port direct current converter comprising: at least one input direct current source; at least one storage battery; a primary side circuit; a secondary side circuit; a first single magnetic component shared by the primary side circuit and the secondary side circuit, wherein the primary side...

Adjustable direct current and pulsed circuit fault current limiter

Science.gov (United States)

Boenig, Heinrich J.; Schillig, Josef B.

2003-09-23

A fault current limiting system for direct current circuits and for pulsed power circuit. In the circuits, a current source biases a diode that is in series with the circuits' transmission line. If fault current in a circuit exceeds current from the current source biasing the diode open, the diode will cease conducting and route the fault current through the current source and an inductor. This limits the rate of rise and the peak value of the fault current.

Battery Test Manual For 48 Volt Mild Hybrid Electric Vehicles

Energy Technology Data Exchange (ETDEWEB)

Walker, Lee Kenneth [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2017-03-01

This manual details the U.S. Advanced Battery Consortium and U.S. Department of Energy Vehicle Technologies Program goals, test methods, and analysis techniques for a 48 Volt Mild Hybrid Electric Vehicle system. The test methods are outlined stating with characterization tests, followed by life tests. The final section details standardized analysis techniques for 48 V systems that allow for the comparison of different programs that use this manual. An example test plan is included, along with guidance to filling in gap table numbers.

Battery Test Manual For 48 Volt Mild Hybrid Electric Vehicles

International Nuclear Information System (INIS)

Walker, Lee Kenneth

2017-01-01

This manual details the U.S. Advanced Battery Consortium and U.S. Department of Energy Vehicle Technologies Program goals, test methods, and analysis techniques for a 48 Volt Mild Hybrid Electric Vehicle system. The test methods are outlined stating with characterization tests, followed by life tests. The final section details standardized analysis techniques for 48 V systems that allow for the comparison of different programs that use this manual. An example test plan is included, along with guidance to filling in gap table numbers.

Evaluation of Requirements for Volt/Var Control and Optimization Function in Distribution Management Systems

DEFF Research Database (Denmark)

Rahimi, Saaed; Marinelli, Mattia; Silvestro, Federico

2012-01-01

To meet the requirement from new visions within “smart grid” and to provide solutions for many challenges that DSOs (Distribution System Operators) are facing today, we need to develop advanced DMS (Distribution Management System) applications. A centralized Volt/Var Control (VVC) is one of the m...

Effect of low temperature and electron irradiation on the volt-ampere characteristics of silicon structures with p-n junctions; Vliyanie nizkikh temperatur i ehlektronnogo oblucheniya na vol`t-ampernye kharakteristiki kremnievykh struktur s p-n perekhodami

Energy Technology Data Exchange (ETDEWEB)

Korshunov, F P [and others

1994-12-31

Features of volt-ampere characteristic behaviour of silicon, diffusion p-n-p structures making up the basis of force diodes under their operation in the mode of nominal and overload current densities are investigated.

Enhanced motor learning with bilateral transcranial direct current stimulation: Impact of polarity or current flow direction?

Science.gov (United States)

Naros, Georgios; Geyer, Marc; Koch, Susanne; Mayr, Lena; Ellinger, Tabea; Grimm, Florian; Gharabaghi, Alireza

2016-04-01

Bilateral transcranial direct current stimulation (TDCS) is superior to unilateral TDCS when targeting motor learning. This effect could be related to either the current flow direction or additive polarity-specific effects on each hemisphere. This sham-controlled randomized study included fifty right-handed healthy subjects in a parallel-group design who performed an exoskeleton-based motor task of the proximal left arm on three consecutive days. Prior to training, we applied either sham, right anodal (a-TDCS), left cathodal (c-TDCS), concurrent a-TDCS and c-TDCS with two independent current sources and return electrodes (double source (ds)-TDCS) or classical bilateral stimulation (bi-TDCS). Motor performance improved over time for both unilateral (a-TDCS, c-TDCS) and bilateral (bi-TDCS, ds-TDCS) TDCS montages. However, only the two bilateral paradigms led to an improvement of the final motor performance at the end of the training period as compared to the sham condition. There was no difference between the two bilateral stimulation conditions (bi-TDCS, ds-TDCS). Bilateral TDCS is more effective than unilateral stimulation due to its polarity-specific effects on each hemisphere rather than due to its current flow direction. This study is the first systematic evaluation of stimulation polarity and current flow direction of bi-hemispheric motor cortex TDCS on motor learning of proximal upper limb muscles. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

How many electric miles do Nissan Leafs and Chevrolet Volts in The EV Project travel?

Energy Technology Data Exchange (ETDEWEB)

John Smart

2014-05-01

This paper presents travel statistics and metrics describing the driving behavior of Nissan Leaf and Chevrolet Volt drivers in the EV Project. It specifically quantifies the distance each group of vehicles drives each month. This paper will be published to INL's external website and will be accessible by the general public.

75 FR 21353 - Intel Corporation, Fab 20 Division, Including On-Site Leased Workers From Volt Technical...

Science.gov (United States)

2010-04-23

... DEPARTMENT OF LABOR Employment and Training Administration [TA-W-73,642] Intel Corporation, Fab 20... of Intel Corporation, Fab 20 Division, including on-site leased workers of Volt Technical Resources... Precision, Inc. were employed on-site at the Hillsboro, Oregon location of Intel Corporation, Fab 20...

Stability analysis of direct current control in current source rectifier

DEFF Research Database (Denmark)

Lu, Dapeng; Wang, Xiongfei; Blaabjerg, Frede

2017-01-01

Current source rectifier with high switching frequency has a great potential for improving the power efficiency and power density in ac-dc power conversion. This paper analyzes the stability of direct current control based on the time delay effect. Small signal model including dynamic behaviors...

EOP Current Magnitude and Direction

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — These data contain shipboard current magnitudes and directions collected in the Pacific, both pelagic and near shore environments. Data is collected using an RD...

Direct extraction of negative lithium ions from a lithium plasma

International Nuclear Information System (INIS)

Wada, M.; Tsuda, H.; Sasao, M.

1990-01-01

Negative lithium ions (Li - ) were directly extracted from a lithium plasma in a multiline cusp plasma container. A pair of permanent magnets mounted near the extractor electrode created the filter magnetic field that separated the extraction region plasma from the main discharge plasma. The plasma electrode facing the extraction region plasma was biased with respect to the other parts of the chamber wall, which acted as discharge anodes. The larger filter magnetic field resulted larger Li - current. When the bias to the plasma electrode was several volts positive against the anode potential, extracted Li - current took the maximum for a fixed strength of the filter field. These dependences of Li - upon the filter magnetic field and the plasma electrode bias are similar to the ones of negative hydrogen ions

A new HBMO algorithm for multiobjective daily Volt/Var control in distribution systems considering Distributed Generators

Energy Technology Data Exchange (ETDEWEB)

Niknam, Taher [Electrical and Electronics Engineering Department, Shiraz University of Technology, Modars Blvd. P.O. 71555-313, Shiraz (Iran, Islamic Republic of)

2011-03-15

In recent years, Distributed Generators (DGs) connected to the distribution network have received increasing attention. The connection of enormous DGs into existing distribution network changes the operation of distribution systems. Because of the small X/R ratio and radial structure of distribution systems, DGs affect the daily Volt/Var control. This paper presents a new algorithm for multiobjective daily Volt/Var control in distribution systems including Distributed Generators (DGs). The objectives are costs of energy generation by DGs and distribution companies, electrical energy losses and the voltage deviations for the next day. A new optimization algorithm based on a Chaotic Improved Honey Bee Mating Optimization (CIHBMO) is proposed to determine the active power values of DGs, reactive power values of capacitors and tap positions of transformers for the next day. Since objectives are not the same, a fuzzy system is used to calculate the best solution. The plausibility of the proposed algorithm is demonstrated and its performance is compared with other methods on a 69-bus distribution feeder. Simulation results illustrate that the proposed algorithm has better outperforms the other algorithms. (author)

A new HBMO algorithm for multiobjective daily Volt/Var control in distribution systems considering Distributed Generators

International Nuclear Information System (INIS)

Niknam, Taher

2011-01-01

In recent years, Distributed Generators (DGs) connected to the distribution network have received increasing attention. The connection of enormous DGs into existing distribution network changes the operation of distribution systems. Because of the small X/R ratio and radial structure of distribution systems, DGs affect the daily Volt/Var control. This paper presents a new algorithm for multiobjective daily Volt/Var control in distribution systems including Distributed Generators (DGs). The objectives are costs of energy generation by DGs and distribution companies, electrical energy losses and the voltage deviations for the next day. A new optimization algorithm based on a Chaotic Improved Honey Bee Mating Optimization (CIHBMO) is proposed to determine the active power values of DGs, reactive power values of capacitors and tap positions of transformers for the next day. Since objectives are not the same, a fuzzy system is used to calculate the best solution. The plausibility of the proposed algorithm is demonstrated and its performance is compared with other methods on a 69-bus distribution feeder. Simulation results illustrate that the proposed algorithm has better outperforms the other algorithms.

WORK SYSTEM ANALYSIS OF POWER SUPPLY IN OPTIMIZING ELECTRICITY ON PERSONAL COMPUTER (PC

Directory of Open Access Journals (Sweden)

Sudarmaji Sudarmaji

2017-12-01

Full Text Available Working Principles DC Power Supply - is an energy source for a computer to operate. The power supply changes the current from AC 110 volts to 60Hz or 220 volts 50Hz to DC + 3.3 volts, +5 volts and + 12 volts. Power Supply must carry a good and stable DC power supply so the system can run well. Tools running on the voltage supplied by the onboard voltage regulator, for example RIMM and RIMM require 2.5 volts while AGP AX and cards require 1.5 volts, both supplied by the onboard regulator of the motherboard. In addition to supplying power, the Power Supply can prevent the computer from starting until a Power Supply voltage exists at a predetermined area. Power Good is a sign of a special test that is sent to the motherboard as an active signal on the computer, usually marked by a green light when the power button is pressed. The current issued by the Power Supply is a direct current (DC, power output is composed of 200 watts, 250 watts, 300 watts, 350 watts, 400 watts to 600 watts. Computers with Intel Pentium 4 processors and above use power of 380 watts to 450 watts. Keywords: Power Supply, Computer, DC, Power Good, and volt

Connectivity-Enhanced Route Selection and Adaptive Control for the Chevrolet Volt: Preprint

Energy Technology Data Exchange (ETDEWEB)

Gonder, J.; Wood, E.; Rajagopalan, S.

2014-09-01

The National Renewable Energy Laboratory and General Motors evaluated connectivity-enabled efficiency enhancements for the Chevrolet Volt. A high-level model was developed to predict vehicle fuel and electricity consumption based on driving characteristics and vehicle state inputs. These techniques were leveraged to optimize energy efficiency via green routing and intelligent control mode scheduling, which were evaluated using prospective driving routes between tens of thousands of real-world origin/destination pairs. The overall energy savings potential of green routing and intelligent mode scheduling was estimated at 5% and 3% respectively. These represent substantial opportunities considering that they only require software adjustments to implement.

Power Hardware-in-the-Loop Testing of Multiple Photovoltaic Inverters' Volt-Var Control with Real-Time Grid Model

Energy Technology Data Exchange (ETDEWEB)

Chakraborty, Sudipta; Nelson, Austin; Hoke, Anderson

2016-12-12

Traditional testing methods fall short in evaluating interactions between multiple smart inverters providing advanced grid support functions due to the fact that such interactions largely depend on their placements on the electric distribution systems with impedances between them. Even though significant concerns have been raised by the utilities on the effects of such interactions, little effort has been made to evaluate them. In this paper, power hardware-in-the-loop (PHIL) based testing was utilized to evaluate autonomous volt-var operations of multiple smart photovoltaic (PV) inverters connected to a simple distribution feeder model. The results provided in this paper show that depending on volt-var control (VVC) parameters and grid parameters, interaction between inverters and between the inverter and the grid is possible in some extreme cases with very high VVC slopes, fast response times and large VVC response delays.

The VESUVIO electron volt neutron spectrometer

Science.gov (United States)

Mayers, J.; Reiter, G.

2012-04-01

This paper describes the VESUVIO electron volt neutron spectrometer at the ISIS pulsed neutron source and its data analysis routines. VESUVIO is used primarily for the measurement of proton momentum distributions in condensed matter systems, but can also be used to measure the kinetic energies of heavier masses and bulk in-situ sample compositions. A series of VESUVIO runs on the same zirconium hydride sample over the past two years show that (1) kinetic energies of protons can be measured to an absolute accuracy of ˜1%. (2) Measurements of the proton momentum distribution n(p) are highly reproducible from run to run. This shows that small changes in kinetic energy and the detailed shape of n(p) with parameters such as temperature, pressure and sample composition can be reliably extracted from VESUVIO data. (3) The impulse approximation (IA) is well satisfied on VESUVIO. (4) The small deviations from the IA due to the finite momentum transfer of measurement are well understood. (5) There is an anomaly in the magnitude of the inelastic neutron cross-section of the protons in zirconium hydride, with an observed reduction of 10% ± 0.3% from that given in standard tables. This anomaly is independent of energy transfer to within experimental error. Future instrument developments are discussed. These would allow the measurement of n(p) in other light atoms, D, 3He, 4He, Li, C and O and measurement of eV electronic and magnetic excitations.

The VESUVIO electron volt neutron spectrometer

International Nuclear Information System (INIS)

Mayers, J; Reiter, G

2012-01-01

This paper describes the VESUVIO electron volt neutron spectrometer at the ISIS pulsed neutron source and its data analysis routines. VESUVIO is used primarily for the measurement of proton momentum distributions in condensed matter systems, but can also be used to measure the kinetic energies of heavier masses and bulk in-situ sample compositions. A series of VESUVIO runs on the same zirconium hydride sample over the past two years show that (1) kinetic energies of protons can be measured to an absolute accuracy of ∼1%. (2) Measurements of the proton momentum distribution n(p) are highly reproducible from run to run. This shows that small changes in kinetic energy and the detailed shape of n(p) with parameters such as temperature, pressure and sample composition can be reliably extracted from VESUVIO data. (3) The impulse approximation (IA) is well satisfied on VESUVIO. (4) The small deviations from the IA due to the finite momentum transfer of measurement are well understood. (5) There is an anomaly in the magnitude of the inelastic neutron cross-section of the protons in zirconium hydride, with an observed reduction of 10% ± 0.3% from that given in standard tables. This anomaly is independent of energy transfer to within experimental error. Future instrument developments are discussed. These would allow the measurement of n(p) in other light atoms, D, 3 He, 4 He, Li, C and O and measurement of eV electronic and magnetic excitations. (paper)

Direct current power delivery system and method

Science.gov (United States)

Zhang, Di; Garces, Luis Jose; Dai, Jian; Lai, Rixin

2016-09-06

A power transmission system includes a first unit for carrying out the steps of receiving high voltage direct current (HVDC) power from an HVDC power line, generating an alternating current (AC) component indicative of a status of the first unit, and adding the AC component to the HVDC power line. Further, the power transmission system includes a second unit for carrying out the steps of generating a direct current (DC) voltage to transfer the HVDC power on the HVDC power line, wherein the HVDC power line is coupled between the first unit and the second unit, detecting a presence or an absence of the added AC component in the HVDC power line, and determining the status of the first unit based on the added AC component.

Application of volt-chins for determination of ionic components in real and chemical Gibbs transition energies of individual ions from water in aqueous-organic solvents

International Nuclear Information System (INIS)

Parfenyuk, V.I.

2007-01-01

Thermodynamic description of separate ions (among which is I - ) in individual and mixed solvents is conducted on the basis of the volt potential difference method. Application of the presented methodology serves as one of candidates problem solving of individual ions thermodynamic characterisation in solutions. Validity of application of the volt potential difference method for the determination of ionic components in real and chemical thermodynamic properties of separate ions in solutions as well as surface potential values on the solution-gas phase interfaces is demonstrated [ru

Transcranial cerebellar direct current stimulation and transcutaneous spinal cord direct current stimulation as innovative tools for neuroscientists

Science.gov (United States)

Priori, Alberto; Ciocca, Matteo; Parazzini, Marta; Vergari, Maurizio; Ferrucci, Roberta

2014-01-01

Two neuromodulatory techniques based on applying direct current (DC) non-invasively through the skin, transcranial cerebellar direct current stimulation (tDCS) and transcutaneous spinal DCS, can induce prolonged functional changes consistent with a direct influence on the human cerebellum and spinal cord. In this article we review the major experimental works on cerebellar tDCS and on spinal tDCS, and their preliminary clinical applications. Cerebellar tDCS modulates cerebellar motor cortical inhibition, gait adaptation, motor behaviour, and cognition (learning, language, memory, attention). Spinal tDCS influences the ascending and descending spinal pathways, and spinal reflex excitability. In the anaesthetised mouse, DC stimulation applied under the skin along the entire spinal cord may affect GABAergic and glutamatergic systems. Preliminary clinical studies in patients with cerebellar disorders, and in animals and patients with spinal cord injuries, have reported beneficial effects. Overall the available data show that cerebellar tDCS and spinal tDCS are two novel approaches for inducing prolonged functional changes and neuroplasticity in the human cerebellum and spinal cord, and both are new tools for experimental and clinical neuroscientists. PMID:24907311

Water Electrolysis at Different Current - Voltage Regimes

International Nuclear Information System (INIS)

Kleperis, J.; Blums, J.; Vanags, M.

2007-01-01

Full text: Electrochemical impedance and volt-amperic methods were used to compare an efficiency of water electrolysis for different materials and different electrode configurations. Two and three electrode measurements were made, using standard calomel reference electrode. Non-standard capacitative electrolysis was analyzed in special cell made from cylindrical steel electrodes. Volt-amperic measurements from - 15V to +15V DC didn't indicated the presence of oxidation - reduction reactions when distilled water was used as electrolyte. Impedance measurements showed unusual frequency behavior when the AC voltage increased till 0.5V. Different nickel and carbon electrodes (plate, porous and textile - type) were used to learn classical Faraday electrolysis in strong alkali solutions. Flying increase of current was indicator of the presence of electrolysis, and characteristic potential was used differ between materials accordingly they effectiveness for usage in an electrolyser device. (Aithors)

Is transcranial direct current stimulation a potential method for improving response inhibition?

Science.gov (United States)

Kwon, Yong Hyun; Kwon, Jung Won

2013-04-15

Inhibitory control of movement in motor learning requires the ability to suppress an inappropriate action, a skill needed to stop a planned or ongoing motor response in response to changes in a variety of environments. This study used a stop-signal task to determine whether transcranial direct-current stimulation over the pre-supplementary motor area alters the reaction time in motor inhibition. Forty healthy subjects were recruited for this study and were randomly assigned to either the transcranial direct-current stimulation condition or a sham-transcranial direct-current stimulation condition. All subjects consecutively performed the stop-signal task before, during, and after the delivery of anodal transcranial direct-current stimulation over the pre-supplementary motor area (pre-transcranial direct-current stimulation phase, transcranial direct-current stimulation phase, and post-transcranial direct-current stimulation phase). Compared to the sham condition, there were significant reductions in the stop-signal processing times during and after transcranial direct-current stimulation, and change times were significantly greater in the transcranial direct-current stimulation condition. There was no significant change in go processing-times during or after transcranial direct-current stimulation in either condition. Anodal transcranial direct-current stimulation was feasibly coupled to an interactive improvement in inhibitory control. This coupling led to a decrease in the stop-signal process time required for the appropriate responses between motor execution and inhibition. However, there was no transcranial direct-current stimulation effect on the no-signal reaction time during the stop-signal task. Transcranial direct-current stimulation can adjust certain behaviors, and it could be a useful clinical intervention for patients who have difficulties with response inhibition.

Mega-electron-volt ultrafast electron diffraction at SLAC National Accelerator Laboratory

Energy Technology Data Exchange (ETDEWEB)

Weathersby, S. P.; Brown, G.; Chase, T. F.; Coffee, R.; Corbett, J.; Eichner, J. P.; Frisch, J. C.; Fry, A. R.; Gühr, M.; Hartmann, N.; Hast, C.; Hettel, R.; Jobe, R. K.; Jongewaard, E. N.; Lewandowski, J. R.; Li, R. K., E-mail: lrk@slac.stanford.edu; Lindenberg, A. M.; Makasyuk, I.; May, J. E.; McCormick, D. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); and others

2015-07-15

Ultrafast electron probes are powerful tools, complementary to x-ray free-electron lasers, used to study structural dynamics in material, chemical, and biological sciences. High brightness, relativistic electron beams with femtosecond pulse duration can resolve details of the dynamic processes on atomic time and length scales. SLAC National Accelerator Laboratory recently launched the Ultrafast Electron Diffraction (UED) and microscopy Initiative aiming at developing the next generation ultrafast electron scattering instruments. As the first stage of the Initiative, a mega-electron-volt (MeV) UED system has been constructed and commissioned to serve ultrafast science experiments and instrumentation development. The system operates at 120-Hz repetition rate with outstanding performance. In this paper, we report on the SLAC MeV UED system and its performance, including the reciprocal space resolution, temporal resolution, and machine stability.

Photovoltaic Impact Assessment of Smart Inverter Volt-VAR Control on Distribution System Conservation Voltage Reduction and Power Quality

Energy Technology Data Exchange (ETDEWEB)

Ding, Fei [National Renewable Energy Lab. (NREL), Golden, CO (United States); Nagarajan, Adarsh [National Renewable Energy Lab. (NREL), Golden, CO (United States); Chakraborty, Sudipta [National Renewable Energy Lab. (NREL), Golden, CO (United States); Baggu, Murali [National Renewable Energy Lab. (NREL), Golden, CO (United States); Nguyen, Andu [SolarCity, San Mateo, CA (United States); Walinga, Sarah [SolarCity, San Mateo, CA (United States); McCarty, Michael [SolarCity, San Mateo, CA (United States); Bell, Frances [SolarCity, San Mateo, CA (United States)

2016-12-01

This report presents an impact assessment study of distributed photovoltaic (PV) with smart inverter Volt-VAR control on conservation voltage reduction (CVR) energy savings and distribution system power quality. CVR is a methodology of flattening and lowering a distribution system voltage profile in order to conserve energy. Traditional CVR relies on operating utility voltage regulators and switched capacitors. However, with the increased penetration of distributed PV systems, smart inverters provide the new opportunity to control local voltage and power factor by regulating the reactive power output, leading to a potential increase in CVR energy savings. This report proposes a methodology to implement CVR scheme by operating voltage regulators, capacitors, and autonomous smart inverter Volt-VAR control in order to achieve increased CVR benefit. Power quality is an important consideration when operating a distribution system, especially when implementing CVR. It is easy to measure the individual components that make up power quality, but a comprehensive method to incorporate all of these values into a single score has yet to be undertaken. As a result, this report proposes a power quality scoring mechanism to measure the relative power quality of distribution systems using a single number, which is aptly named the 'power quality score' (PQS). Both the CVR and PQS methodologies were applied to two distribution system models, one obtained from the Hawaiian Electric Company (HECO) and another obtained from Pacific Gas and Electric (PG&E). These two models were converted to the OpenDSS platform using previous model conversion tools that were developed by NREL. Multiple scenarios including various PV penetration levels and smart inverter densities were simulated to analyze the impact of smart inverter Volt-VAR support on CVR energy savings and feeder power quality. In order to analyze the CVR benefit and PQS, an annual simulation was conducted for each

Transcranial Direct Current Stimulation in Epilepsy.

Science.gov (United States)

San-Juan, Daniel; Morales-Quezada, León; Orozco Garduño, Adolfo Josué; Alonso-Vanegas, Mario; González-Aragón, Maricarmen Fernández; Espinoza López, Dulce Anabel; Vázquez Gregorio, Rafael; Anschel, David J; Fregni, Felipe

2015-01-01

Transcranial direct current stimulation (tDCS) is an emerging non-invasive neuromodulation therapy in epilepsy with conflicting results in terms of efficacy and safety. Review the literature about the efficacy and safety of tDCS in epilepsy in humans and animals. We searched studies in PubMed, MedLine, Scopus, Web of Science and Google Scholar (January 1969 to October 2013) using the keywords 'transcranial direct current stimulation' or 'tDCS' or 'brain polarization' or 'galvanic stimulation' and 'epilepsy' in animals and humans. Original articles that reported tDCS safety and efficacy in epileptic animals or humans were included. Four review authors independently selected the studies, extracted data and assessed the methodological quality of the studies using the recommendations of the Cochrane Handbook for Systematic Reviews of Interventions, PRISMA guidelines and Jadad Scale. A meta-analysis was not possible due to methodological, clinical and statistical heterogeneity of included studies. We analyzed 9 articles with different methodologies (3 animals/6 humans) with a total of 174 stimulated individuals; 109 animals and 65 humans. In vivo and in vitro animal studies showed that direct current stimulation can successfully induce suppression of epileptiform activity without neurological injury and 4/6 (67%) clinical studies showed an effective decrease in epileptic seizures and 5/6 (83%) reduction of inter-ictal epileptiform activity. All patients tolerated tDCS well. tDCS trials have demonstrated preliminary safety and efficacy in animals and patients with epilepsy. Further larger studies are needed to define the best stimulation protocols and long-term follow-up. Copyright © 2015 Elsevier Inc. All rights reserved.

Frontal transcranial direct current stimulation (tDCS) abolishes list-method directed forgetting.

Science.gov (United States)

Silas, Jonathan; Brandt, Karen R

2016-03-11

It is a point of controversy as to whether directed forgetting effects are a result of active inhibition or a change of context initiated by the instruction to forget. In this study we test the causal role of active inhibition in directed forgetting. By applying cathodal transcranial direct current stimulation (tDCS) over the right prefrontal cortex we suppressed cortical activity commonly associated with inhibitory control. Participants who underwent real brain stimulation before completing the directed forgetting paradigm showed no directed forgetting effects. Conversely, those who underwent sham brain stimulation demonstrated classical directed forgetting effects. We argue that these findings suggest that inhibition is the primary mechanism that results in directed forgetting costs and benefits. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Navy Telemedicine: Current Research and Future Directions

National Research Council Canada - National Science Library

Reed, Cheryl

2002-01-01

.... This report reviews military and civilian models for evaluating telemedicine systems in order to determine future directions for Navy telemedicine research within the current funding environment...

Reversal thyristor-relay direct current commutator

International Nuclear Information System (INIS)

Ivanenko, A.I.

1982-01-01

A thyristor-relay commutator used for alteration of the leading magnetic field direction in experiments with polarized neutrons is described. The commutator flowsheet is presented. Thyristors, connected so as to allow the relay trigger operation mode, are used as controllable electronic relay. Two connected in series coils with the total inductance of the order of 0.28 H serve as the electronic relay load. The arc-free current commutation is effected at the moment of the minimal current across the load terminals, which allows to easily reverse the current up to 10 A at a volatage, v <= 150 V. The experience gained within a year of operation has shown that the commutator meets the requirements of reliability and tuning

Current Directional Protection of Series Compensated Line Using Intelligent Classifier

Directory of Open Access Journals (Sweden)

M. Mollanezhad Heydarabadi

2016-12-01

Full Text Available Current inversion condition leads to incorrect operation of current based directional relay in power system with series compensated device. Application of the intelligent system for fault direction classification has been suggested in this paper. A new current directional protection scheme based on intelligent classifier is proposed for the series compensated line. The proposed classifier uses only half cycle of pre-fault and post fault current samples at relay location to feed the classifier. A lot of forward and backward fault simulations under different system conditions upon a transmission line with a fixed series capacitor are carried out using PSCAD/EMTDC software. The applicability of decision tree (DT, probabilistic neural network (PNN and support vector machine (SVM are investigated using simulated data under different system conditions. The performance comparison of the classifiers indicates that the SVM is a best suitable classifier for fault direction discriminating. The backward faults can be accurately distinguished from forward faults even under current inversion without require to detect of the current inversion condition.

Direct currents produced by hf heating of plasma

International Nuclear Information System (INIS)

Klima, R.

1974-01-01

In addition to the well-known diffusion currents, toroidal direct currents arise in h.f. heated plasmas as a result of a momentum transfer from the h.f. field to plasma particles. The estimates of steady-state conditions are given for these currents. Particularly, the possibility of stationary operation of a Tokamak device is analyzed. (author)

A variable current bypass shunt for electromagnets

International Nuclear Information System (INIS)

Berndt, M.M.; Lipari, J.J.

1992-11-01

An IGBT is used to control the current in bypass circuits that vary the relative strength of magnets connected in series. Each circuit consists of a water cooled assembly rated for continuous operation at 70 Volts and 0--50 Amperes DC, with 1 KV insulation between control/monitoring elements and magnets. The circuit operates as a 10KHz PWM switcher that includes filters and transient protection

Manufacturing of 380/220 V 63 A power supply panel on UO2 kernel coating unit

International Nuclear Information System (INIS)

Triyono; Mudjiman, Supardjono; Hidayat, Nur

2013-01-01

The panel 380/220 Volts voltage source current 63 Amperes relay AC output on UO 2 kernel coating unit has been manufactured. The activities include: installation and function panel test. The electrical installation of load includes : 220 Volts temperature monitor/controller, 220 Volts scraber pump, 220 Volts vacuum pump, 220 Volts solenoid valve gas and 380 Volts induction furnace. The component of installation includes: 380 Volts earth leakage circuit breaker, 380 Volts relay AC, 220 Volts magnetic circuit breaker, 100/5 Amperes current transformator ratio, voltmeter, ampermeter and push button normally open-close and temperature monitor/control in the box size 70x50x20 cm. The testing of voltage source has been unload and full load to determine the performance of the tool. The result of manufacture and function test voltage source 380/220 Volts at the UO 2 kernel coating unit showed that: the voltage source can work without load and full load safely. The load includes: voltage 380-382 Volts current 4-4,1 Amperes of induction furnace, voltage 223 Volts current 0,5 Amperes of vacuum pump, voltage 223 Volts current 4 Amperes of scraber pump, voltage 223 Volts current 0,3 Amperes of solenoid valve gas and 222 Volts current 0,03 Amperes temperature monitor/control. (author)

Direct Drive Generator for Renewable Power Conversion from Water Currents

International Nuclear Information System (INIS)

Segergren, Erik

2005-01-01

In this thesis permanent magnet direct drive generator for power conversion from water currents is studied. Water currents as a power source involves a number of constrains as well as possibilities, especially when direct drive and permanent magnets are considered. The high power fluxes and low current velocities of a water current, in combination with its natural variations, will affect the way the generator is operated and, flowingly, the appearance of the generator. The work in this thesis can, thus, be categorized into two general topics, generator technology and optimization. Under the first topic, fundamental generator technology is used to increase the efficiency of a water current generator. Under the latter topic, water current generators are optimized to a specific environment. The conclusion drawn from this work is that it is possible to design very low speed direct drive generators with good electromagnetic properties and wide efficiency peak

Onsite-effects of dual-hemisphere versus conventional single-hemisphere transcranial direct current stimulation

Science.gov (United States)

Kwon, Yong Hyun; Jang, Sung Ho

2012-01-01

We performed functional MRI examinations in six right-handed healthy subjects. During functional MRI scanning, transcranial direct current stimulation was delivered with the anode over the right primary sensorimotor cortex and the cathode over the left primary sensorimotor cortex using dual-hemispheric transcranial direct current stimulation. This was compared to a cathode over the left supraorbital area using conventional single-hemispheric transcranial direct current stimulation. Voxel counts and blood oxygenation level-dependent signal intensities in the right primary sensorimotor cortex regions were estimated and compared between the two transcranial direct current stimulation conditions. Our results showed that dual-hemispheric transcranial direct current stimulation induced greater cortical activities than single-hemispheric transcranial direct current stimulation. These findings suggest that dual-hemispheric transcranial direct current stimulation may provide more effective cortical stimulation than single-hemispheric transcranial direct current stimulation. PMID:25624815

Zener diode controls switching of large direct currents

Science.gov (United States)

1965-01-01

High-current zener diode is connected in series with the positive input terminal of a dc supply to block the flow of direct current until a high-frequency control signal is applied across the zener diode. This circuit controls the switching of large dc signals.

FOREWORD: VI Workshop in Electron Volt Neutron Spectroscopy: Frontiers and Horizons

Science.gov (United States)

Seel, A. G.; Senesi, R.; Fernandez-Alonso, F.

2014-12-01

January 2014 saw the congregation in Abingdon (UK) of scientists from across the world, to discuss the current state and future of spectroscopy using epithermal neutrons. This meeting was the sixth in a series of workshops held in collaboration between the Science and Technology Facilities Council (UK) and the Consiglio Nazionale delle Ricerche (Italy), aimed at bringing together researchers with an interest in the use of electron-volt neutrons in spectroscopic studies [1]. This technique is termed Deep Inelastic Neutron Scattering (DINS), and also Neutron Compton Scattering (NCS) in reference to the analogy with Compton scattering of X-rays from electrons. In particular, this meeting centred jointly around experimentalists and theoreticians, formulating animated discussions as to the current overview of DINS and future horizons facing the field. The use of electron Volt neutrons for spectroscopic measurements dates back to the advent of proton-driven spallation neutron sources in the 1970s and 1980s. Following an initial scientific meeting in Los Alamos (USA) [2], the first two meetings in this series were held in Abingdon (UK) in 1995 and 1998, with subsequent meetings held in Santa Fe (USA) in 2005 [3], Oak Ridge National Laboratory (USA) in 2006 [4], and Rome, Italy; in 2010 [5]. The flagship instrument serving a continual user-programme for DINS measurements, and the main focus of this meeting, has been the VESUVIO spectrometer at ISIS [6, 7]. Subsequent instruments like SEQUOIA in the USA [8, 9] and a newer spectrometer in the Bariloche LINAC in Argentina [10, 11] have also been commissioned and began serving a growing user community. The availability of DINS measurements has extended the range of possible spectroscopic techniques that utilise neutrons into the kinematic region of high energy and momentum transfers, shown schematically in Figure 1. Spectroscopic instrument suites such as that of ISIS are thus able to probe processes on timescales across nine

Transcranial Direct Current Stimulation Improves Audioverbal Memory in Stroke Patients.

Science.gov (United States)

Kazuta, Toshinari; Takeda, Kotaro; Osu, Rieko; Tanaka, Satoshi; Oishi, Ayako; Kondo, Kunitsugu; Liu, Meigen

2017-08-01

The aim of this study was to investigate whether anodal transcranial direct current stimulation over the left temporoparietal area improved audioverbal memory performance in stroke patients. Twelve stroke patients with audioverbal memory impairment participated in a single-masked, crossover, and sham-controlled experiment. The anodal or sham transcranial direct current stimulation was applied during the Rey Auditory Verbal Learning Test, which evaluates the ability to recall a list of 15 heard words over five trials. The number of correctly recalled words was compared between the anodal and sham conditions and the influence of transcranial direct current stimulation on serial position effect of the 15 words was also examined. The increase in the number of correctly recalled words from the first to the fifth trial was significantly greater in the anodal condition than in the sham condition (P transcranial direct current stimulation over the left temporoparietal area improved audioverbal memory performance and induced the primacy effect in stroke patients.

Direct current contamination of kilohertz frequency alternating current waveforms.

Science.gov (United States)

Franke, Manfred; Bhadra, Niloy; Bhadra, Narendra; Kilgore, Kevin

2014-07-30

Kilohertz frequency alternating current (KHFAC) waveforms are being evaluated in a variety of physiological settings because of their potential to modulate neural activity uniquely when compared to frequencies in the sub-kilohertz range. However, the use of waveforms in this frequency range presents some unique challenges regarding the generator output. In this study we explored the possibility of undesirable contamination of the KHFAC waveforms by direct current (DC). We evaluated current- and voltage-controlled KHFAC waveform generators in configurations that included a capacitive coupling between generator and electrode, a resistive coupling and combinations of capacitive with inductive coupling. Our results demonstrate that both voltage- and current-controlled signal generators can unintentionally add DC-contamination to a KHFAC signal, and that capacitive coupling is not always sufficient to eliminate this contamination. We furthermore demonstrated that high value inductors, placed in parallel with the electrode, can be effective in eliminating DC-contamination irrespective of the type of stimulator, reducing the DC contamination to less than 1 μA. This study highlights the importance of carefully designing the electronic setup used in KHFAC studies and suggests specific testing that should be performed and reported in all studies that assess the neural response to KHFAC waveforms. Published by Elsevier B.V.

Effect of alternating and direct currents on Pseudomonas ...

African Journals Online (AJOL)

The test media were Muller-Hinton agar and eosin methylene blue (EMB) agar. In this research Pseudomonas aeruginosa which was isolated from patients wounds was examined with levels of alternating and direct current (AC and DC) electrical stimulation (1.5V, 3.5V, 5.5V and 10V) to see if these currents could inhibit P.

Restoring directional growth sense to plants in space

Science.gov (United States)

Gorgolewski, S.

Introduction of new plant classification: electrotropic (Et) and non-electrotropic (nEt) plants gives us a criterion which plants need electric field to grow "normally" in space. The electric field: E is measured in V/m (volt per meter). Do not confuse "electrotropism" understood by some as the response to current flow transversely through the plant's root. This effect was previously described in biological textbooks. I suggest to call it as (Ct) (here C stands for current and t for tropism). In the laboratory we have in the plant growth chamber two transparent to light (wire mesh) conducting sheets separated by m(meters) and V volts potential difference. It has been shown in laboratory that Et is a very important factor in electrotropic plant development. Space experiments with plants grown in orbit from seed to seed have been fully successful only (in my very best knowledge) with nEt plants. The most common nEt plants are grasses (more than 50% of all plants). The nEt plants in space use phototropism as their sensor of direction. In space (and most greenhouses) we have to provide the electric field at least for the Et plants. It has been shown that the electric field is also beneficial to nEt plants which also acquire the sense of direction imposed by stronger than the normal 130V/m E field (vector). The stronger horizontal E field of 1.6kV/m (slightly more than 12 times stronger than 130V/m) does not influence the rate of growth of maize (which is nEt) in 130V/m vertical field or even in the Faraday cage 0V/m. Yet when the maize gets its leaves, they all lean in the horizontal field (1.6kV/m) towards the anode. The direction of the E vector is defined by the E field lines running from the positive to the negative charges. Because the electric forces are a factor of 1038 times stronger than the gravitational forces, it is not important for the E field whether it acts on ions in the gravity or in weightlessness. We have to recall that on the Earth and in space Et

Current and Future Research Directions in Requirements Engineering

Science.gov (United States)

Cheng, Betty H. C.; Atlee, Joanne M.

In this paper, we review current requirements engineering (RE) research and identify future research directions suggested by emerging software needs. First, we overview the state of the art in RE research. The research is considered with respect to technologies developed to address specific requirements tasks, such as elicitation, modeling, and analysis. Such a review enables us to identify mature areas of research, as well as areas that warrant further investigation. Next, we review several strategies for performing and extending RE research results, to help delineate the scope of future research directions. Finally, we highlight what we consider to be the “hot” current and future research topics, which aim to address RE needs for emerging systems of the future.

Hybrid Direct Carbon Fuel Cell Performance with Anode Current Collector Material

DEFF Research Database (Denmark)

Deleebeeck, Lisa; Kammer Hansen, Kent

2015-01-01

collectors were studied: Au, Ni, Ag, and Pt. It was shown that the performance of the direct carbon fuel cell (DCFC) is dependent on the current collector materials, Ni and Pt giving the best performance, due to their catalytic activity. Gold is suggested to be the best material as an inert current collector......The influence of the current collector on the performance of a hybrid direct carbon fuel cell (HDCFC), consisting of solid oxide fuel cell (SOFC) with a molten carbonate-carbon slurry in contact with the anode, has been investigated using current-voltage curves. Four different anode current...

Wind direction/velocity and current direction/velocity data from current meter casts in a world wide distribution from 1970-12-06 to 1991-10-01 (NODC Accession 9700218)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Wind direction/velocity and current direction/velocity data were collected using current meter casts in a world wide distribution from December 6, 1970 to October 1,...

Soft commutated direct current motor [summary of proposed paper

Energy Technology Data Exchange (ETDEWEB)

Hsu, John S.

1998-10-22

A novel soft commutated direct current (DC) motor is introduced. The current of the commutated coil is intentionally drained before the brush disconnects the coil. This prevents the spark generation that normally occurs in conventional DC motors. A similar principle can be applied for DC generators.

Transcutaneous Spinal Direct Current Stimulation (tsDCS

Directory of Open Access Journals (Sweden)

Filippo eCogiamanian

2012-07-01

Full Text Available In the past ten years renewed interest has centered on non-invasive transcutaneous weak direct currents applied over the scalp to modulate cortical excitability (brain polarization or transcranial direct current stimulation, tDCS. Extensive literature shows that tDCS induces marked changes in cortical excitability that outlast stimulation.Aiming at developing a new, non invasive, approach to spinal cord neuromodulation we assessed the after-effects of thoracic transcutaneous spinal DC stimulation (tsDCS on somatosensory potentials (SEPs evoked in healthy subjects by posterior tibial nerve (PTN stimulation. Our findings showed that thoracic anodal tsDCS depresses the cervico-medullary PTN-SEP component (P30 without eliciting adverse effects. tsDCS also modulates post-activation H-reflex dynamics. Later works further confirmed that transcutaneous electric fields modulate spinal cord function. Subsequent studies in our laboratory showed that tsDCS modulates the flexion reflex in the human lower limb. Besides influencing the laser evoked potentials, tsDCS increases pain tolerance in healthy subjects. Hence, though the underlying mechanisms remain speculative, tsDCS modulates activity in lemniscal, spinothalamic and segmental motor systems.Here we review currently available experimental evidence that non-invasive spinal cord stimulation influences spinal function in humans and argue that, by focally modulating spinal excitability, tsDCS could provide a novel therapeutic tool complementary to drugs and invasive spinal cord stimulation in managing various pathologic conditions, including pain.

Supercapacitor performance evaluation in replacing battery based on charging and discharging current characteristics

Science.gov (United States)

Sani, A.; Siahaan, S.; Mubarakah, N.; Suherman

2018-02-01

Supercapacitor is a new device of energy storage, which has much difference between ordinary capacitors and batteries. Supercapacitor have higher capacitance and energy density than regular capacitors. The supercapacitor also has a fast charging time, as well as a long life. To be used as a battery replacement please note the internal parameters of the battery to be replaced. In this paper conducted a simulation study to utilize supercapacitor as a replacement battery. The internal parameters of the battery and the supercapacitor are obtained based on the characteristics of charging and discharging current using a predefined equivalent circuit model. The battery to be replaced is a 12-volt lead-acid type, 6.5 Ah which is used on motorcycles with 6A charging and discharging currents. Super capacitor replacement capacitor is a capacity of 1600F, 2.7V which is connected in series as many as 6 pieces with 16.2 volt terminal voltage and charging current 12A. To obtain the same supercapacitor characteristic as the battery characteristic to be replaced, modification of its internal parameters is made. The results show that the super-capacitor can replace the battery function for 1000 seconds.

Stimulating thought: a functional MRI study of transcranial direct current stimulation in schizophrenia.

Science.gov (United States)

Orlov, Natasza D; O'Daly, Owen; Tracy, Derek K; Daniju, Yusuf; Hodsoll, John; Valdearenas, Lorena; Rothwell, John; Shergill, Sukhi S

2017-09-01

Individuals with schizophrenia typically suffer a range of cognitive deficits, including prominent deficits in working memory and executive function. These difficulties are strongly predictive of functional outcomes, but there is a paucity of effective therapeutic interventions targeting these deficits. Transcranial direct current stimulation is a novel neuromodulatory technique with emerging evidence of potential pro-cognitive effects; however, there is limited understanding of its mechanism. This was a double-blind randomized sham controlled pilot study of transcranial direct current stimulation on a working memory (n-back) and executive function (Stroop) task in 28 individuals with schizophrenia using functional magnetic resonance imaging. Study participants received 30 min of real or sham transcranial direct current stimulation applied to the left frontal cortex. The 'real' and 'sham' groups did not differ in online working memory task performance, but the transcranial direct current stimulation group demonstrated significant improvement in performance at 24 h post-transcranial direct current stimulation. Transcranial direct current stimulation was associated with increased activation in the medial frontal cortex beneath the anode; showing a positive correlation with consolidated working memory performance 24 h post-stimulation. There was reduced activation in the left cerebellum in the transcranial direct current stimulation group, with no change in the middle frontal gyrus or parietal cortices. Improved performance on the executive function task was associated with reduced activity in the anterior cingulate cortex. Transcranial direct current stimulation modulated functional activation in local task-related regions, and in more distal nodes in the network. Transcranial direct current stimulation offers a potential novel approach to altering frontal cortical activity and exerting pro-cognitive effects in schizophrenia. © The Author (2017). Published by Oxford

Clinical Research with Transcranial Direct Current Stimulation (tDCS): Challenges and Future Directions

Science.gov (United States)

Brunoni, Andre Russowsky; Nitsche, Michael A.; Bolognini, Nadia; Bikson, Marom; Wagner, Tim; Merabet, Lotfi; Edwards, Dylan J.; Valero-Cabre, Antoni; Rotenberg, Alexander; Pascual-Leone, Alvaro; Ferrucci, Roberta; Priori, Alberto; Boggio, Paulo; Fregni, Felipe

2011-01-01

Background Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that delivers low-intensity, direct current to cortical areas facilitating or inhibiting spontaneous neuronal activity. In the past ten years, tDCS physiological mechanisms of action have been intensively investigated giving support for the investigation of its applications in clinical neuropsychiatry and rehabilitation. However, new methodological, ethical, and regulatory issues emerge when translating the findings of preclinical and phase I studies into phase II and III clinical studies. The aim of this comprehensive review is to discuss the key challenges of this process and possible methods to address them. Methods We convened a workgroup of researchers in the field to review, discuss and provide updates and key challenges of neuromodulation use for clinical research. Main Findings/Discussion We reviewed several basic and clinical studies in the field and identified potential limitations, taking into account the particularities of the technique. We review and discuss the findings into four topics: (i) mechanisms of action of tDCS, parameters of use and computer-based human brain modeling investigating electric current fields and magnitude induced by tDCS; (ii) methodological aspects related to the clinical research of tDCS as divided according to study phase (i.e., preclinical, phase I, phase II and phase III studies); (iii) ethical and regulatory concerns; (iv) future directions regarding novel approaches, novel devices, and future studies involving tDCS. Finally, we propose some alternative methods to facilitate clinical research on tDCS. PMID:22037126

Combined effects of cerebellar transcranial direct current stimulation and transcutaneous spinal direct current stimulation on robot-assisted gait training in patients with chronic brain stroke: A pilot, single blind, randomized controlled trial.

Science.gov (United States)

Picelli, Alessandro; Chemello, Elena; Castellazzi, Paola; Filippetti, Mirko; Brugnera, Annalisa; Gandolfi, Marialuisa; Waldner, Andreas; Saltuari, Leopold; Smania, Nicola

2018-01-01

Preliminary evidence showed additional effects of anodal transcranial direct current stimulation over the damaged cerebral hemisphere combined with cathodal transcutaneous spinal direct current stimulation during robot-assisted gait training in chronic stroke patients. This is consistent with the neural organization of locomotion involving cortical and spinal control. The cerebellum is crucial for locomotor control, in particular for avoidance of obstacles, and adaptation to novel conditions during walking. Despite its key role in gait control, to date the effects of transcranial direct current stimulation of the cerebellum have not been investigated on brain stroke patients treated with robot-assisted gait training. To evaluate the effects of cerebellar transcranial direct current stimulation combined with transcutaneous spinal direct current stimulation on robot-assisted gait training in patients with chronic brain stroke. After balanced randomization, 20 chronic stroke patients received ten, 20-minute robot-assisted gait training sessions (five days a week, for two consecutive weeks) combined with central nervous system stimulation. Group 1 underwent on-line cathodal transcranial direct current stimulation over the contralesional cerebellar hemisphere + cathodal transcutaneous spinal direct current stimulation. Group 2 received on-line anodal transcranial direct current stimulation over the damaged cerebral hemisphere + cathodal transcutaneous spinal direct current stimulation. The primary outcome was the 6-minute walk test performed before, after, and at follow-up at 2 and 4 weeks post-treatment. The significant differences in the 6-minute walk test noted between groups at the first post-treatment evaluation (p = 0.041) were not maintained at either the 2-week (P = 0.650) or the 4-week (P = 0.545) follow-up evaluations. Our preliminary findings support the hypothesis that cathodal transcranial direct current stimulation over the contralesional

LANMAS core: Update and current directions

International Nuclear Information System (INIS)

Claborn, J.

1995-01-01

Local Area Network Material Accountability system (LANMAS) core software provides the framework of a material accountability system. It tracks the movement of material throughout a site and generates the required material accountability reports. LANMAS is a net-work- based nuclear material accountability system that runs in a client/server mode. The database of material type and location resides on the server, while the user interface runs on the client. The user interface accesses the data stored on the server via a network. The LANMAS core can be used as the foundation for building required materials control and accountability (MCA) functionality at any site requiring a new MCA system. An individual site will build on the LANMAS core by supplying site-specific software. This paper will provide an update on the current LANMAS development activities and discuss the current direction of the LANMAS project

Current control for magnetized plasma in direct-current plasma-immersion ion implantation

International Nuclear Information System (INIS)

Tang Deli; Chu, Paul K.

2003-01-01

A method to control the ion current in direct-current plasma-immersion ion implantation (PIII) is reported for low-pressure magnetized inductively coupled plasma. The ion current can be conveniently adjusted by applying bias voltage to the conducting grid that separates plasma formation and implantation (ion acceleration) zones without the need to alter the rf input power, gas flux, or other operating conditions. The ion current that diminishes with an increase in grid bias in magnetized plasmas can be varied from 48 to 1 mA by increasing the grid voltage from 0 to 70 V at -50 kV sample bias and 0.5 mTorr hydrogen pressure. High implantation voltage and monoenergetic immersion implantation can now be achieved by controlling the ion current without varying the macroscopic plasma parameters. The experimental results and interpretation of the effects are presented in this letter. This technique is very attractive for PIII of planar samples that require on-the-fly adjustment of the implantation current at high implantation voltage but low substrate temperature. In some applications such as hydrogen PIII-ion cut, it may obviate the need for complicated sample cooling devices that must work at high voltage

Multitarget transcranial direct current stimulation for freezing of gait in Parkinson's disease.

Science.gov (United States)

Dagan, Moria; Herman, Talia; Harrison, Rachel; Zhou, Junhong; Giladi, Nir; Ruffini, Giulio; Manor, Brad; Hausdorff, Jeffrey M

2018-04-01

Recent findings suggest that transcranial direct current stimulation of the primary motor cortex may ameliorate freezing of gait. However, the effects of multitarget simultaneous stimulation of motor and cognitive networks are mostly unknown. The objective of this study was to evaluate the effects of multitarget transcranial direct current stimulation of the primary motor cortex and left dorsolateral prefrontal cortex on freezing of gait and related outcomes. Twenty patients with Parkinson's disease and freezing of gait received 20 minutes of transcranial direct current stimulation on 3 separate visits. Transcranial direct current stimulation targeted the primary motor cortex and left dorsolateral prefrontal cortex simultaneously, primary motor cortex only, or sham stimulation (order randomized and double-blinded assessments). Participants completed a freezing of gait-provoking test, the Timed Up and Go, and the Stroop test before and after each transcranial direct current stimulation session. Performance on the freezing of gait-provoking test (P = 0.010), Timed Up and Go (P = 0.006), and the Stroop test (P = 0.016) improved after simultaneous stimulation of the primary motor cortex and left dorsolateral prefrontal cortex, but not after primary motor cortex only or sham stimulation. Transcranial direct current stimulation designed to simultaneously target motor and cognitive regions apparently induces immediate aftereffects in the brain that translate into reduced freezing of gait and improvements in executive function and mobility. © 2018 International Parkinson and Movement Disorder Society. © 2018 International Parkinson and Movement Disorder Society.

Limiting currents in superconducting composites

International Nuclear Information System (INIS)

Keilin, V.E.; Romanovskii, V.R.

1992-01-01

In this paper the results of numerical and analytical calculations of the process of current charging into a round superconducting composite with properties homogenized over cross-section are presented. In the numerical solution taken was into account a common proceeding of the thermal and electromagnetic processes. A wire with real volt-ampere characteristics approximated by exponential dependence was considered. The calculations carried out at various rates of current charging, voltampere characteristics, matrix materials, heat transfer coefficients and other parameters showed: the existence of characteristic limiting value of current below which the wire remains in a superconducting state if the current charging ceases and above which changes into a normal state; this current is somewhat less than a quench current; the existence of finite value for limiting current at any low heat transfer from a surface. The analytical solution of the problem is given. It permitted to write the stability criterion from which the dependence of limiting currents on initial parameters follows. The wire nonisothermality, its heat capacity, thermal and electric conductivities are taken into account additionally, as compared to results published earlier

Influence of Waveform and Current Direction on Short-Interval Intracortical Facilitation

DEFF Research Database (Denmark)

Delvendahl, Igor; Lindemann, Hannes; Jung, Nikolai H

2014-01-01

-posterior (AP) current direction (AP-AP or PA-PA), whereas current direction was reversed between first and second pulse for half-sine paired-pulse stimulation (PA-AP and AP-PA). RESULTS: Monophasic AP-AP stimulation resulted in stronger early SICF at 1.4 ms relative to late SICF at 2.8 and 4.4 ms, whereas...... monophasic PA-PA stimulation produced SICF of comparable size at all three peaks. With half-sine stimulation the third SICF peak was reduced for PA-AP current orientation compared with AP-PA. CONCLUSION: SICF elicited using monophasic as well as half-sine pulses is affected by current direction at clearly......BACKGROUND: Transcranial magnetic stimulation (TMS) of the human primary motor hand area (M1-HAND) can produce multiple descending volleys in fast-conducting corticospinal neurons, especially so-called indirect waves (I-waves) resulting from trans-synaptic excitation. Facilitatory interaction...

Safety Parameter Considerations of Anodal Transcranial Direct Current Stimulation in Rats

Science.gov (United States)

2017-10-01

Richardson, J.D., Baker, J.M., Rorden, C., 2011. Transcranial direct current stimulation improves naming reaction time in fluent aphasia: a...AFRL-RH-WP-TR-2017-0069 Safety parameter considerations of anodal transcranial Direct Current Stimulation in rats R. Andy McKinley...response, including the time for reviewing instructions, searching existing data sources, searching existing data sources, gathering and maintaining the

Onsite-effects of dual-hemisphere versus conventional single-hemisphere transcranial direct current stimulation

OpenAIRE

Kwon, Yong Hyun; Jang, Sung Ho

2012-01-01

We performed functional MRI examinations in six right-handed healthy subjects. During functional MRI scanning, transcranial direct current stimulation was delivered with the anode over the right primary sensorimotor cortex and the cathode over the left primary sensorimotor cortex using dual-hemispheric transcranial direct current stimulation. This was compared to a cathode over the left supraorbital area using conventional single-hemispheric transcranial direct current stimulation. Voxel coun...

Subcortical structures in humans can be facilitated by transcranial direct current stimulation

NARCIS (Netherlands)

Nonnekes, Johan Hendrik; Arrogi, Anass; Munneke, Moniek; van Asseldonk, Edwin H.F.; Oude Nijhuis, Lars; Geurts, Alexander; Weerdesteyn, Vivian

2014-01-01

BACKGROUND: Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that alters cortical excitability via application of a weak direct current. Interestingly, it was demonstrated in cats that tDCS can facilitate subcortical structures as well (Bolzonii et al., J

Co-ordination of directional overcurrent protection with load current for parallel feeders

Energy Technology Data Exchange (ETDEWEB)

Wright, J.W.; Lloyd, G.; Hindle, P.J. [Alstom, Inc., Stafford (United Kingdom). T and D Protection and Control

1999-11-01

Directional phase overcurrent relays are commonly applied at the receiving ends of parallel feeders or transformer feeders. Their purpose is to ensure full discrimination of main or back-up power system overcurrent protection for a fault near the receiving end of one feeder. This paper reviews this type of relay application and highlights load current setting constraints for directional protection. Such constraints have not previously been publicized in well-known text books. A directional relay current setting constraint that is suggested in some text books is based purely on thermal rating considerations for older technology relays. This constraint may not exist with modern numerical relays. In the absence of any apparent constraint, there is a temptation to adopt lower current settings with modern directional relays in relation to reverse load current at the receiving ends of parallel feeders. This paper identifies the danger of adopting very low current settings without any special relay feature to ensure protection security with load current during power system faults. A system incident recorded by numerical relays is also offered to highlight this danger. In cases where there is a need to infringe the identified constraints an implemented and testing relaying technique is proposed.

LANMAS core: Update and current directions

International Nuclear Information System (INIS)

Claborn, J.

1994-01-01

Local Area Network Material Accountability System (LANMAS) core software will provide the framework of a material accountability system. LANMAS is a network-based nuclear material accountability system. It tracks the movement of material throughout a site and generates the required reports on material accountability. LANMAS will run in a client/server mode. The database of material type and location will reside on the server, while the user interface runs on the client. The user interface accesses the server via a network. The LANMAS core can be used as the foundation for building required Materials Control and Accountability (MC ampersand A) functionality at any site requiring a new MC ampersand A system. An individual site will build on the LANMAS core by supplying site-specific software. This paper will provide an update on the current LANMAS development activities and discuss the current direction of the LANMAS project

Experimental study of anti-tumor activity of direct current

International Nuclear Information System (INIS)

Ito, Hisao; Hashimoto, Shozo

1989-01-01

The anti-tumor activity of direct current combined with radiation was studied. The experiments were performed with fibrosarcomas (FSA, NFSA) syngenetic to C3H mice. Direct current (0.6mA, 120min) alone was effective to reduce the tumor sizes, but could not cure the tumors. When the direct current therapy (DC therapy) was combined with radiation the DC therapy following radiation was more effective than that before radiation. Using TCD 50 assay, the DC therapy enhanced the effect of a single dose of radiation with the dose-modifying factor of 1.2. However, tumor control rates by the combination therapy were more improved at the smaller doses of radiation than at the larger ones. When the single DC therapy (0.6mA, 120min) was applied immediately after the first radiation of fractionated one the combination therapy still showed the enhanced effect. However, both DC therapy and the radiation therapy were divided in three fractions, and the DC therapy (0.6mA, 40min) was applied after each radiation. Tumor growth retardation by the combination therapy was no different from that by radiation alone. This result suggests that there might be a minimum required dose of coulombs to show the effect of the combination therapy. (author)

Transcranial direct current stimulation enhances propulsion during walking

NARCIS (Netherlands)

van Asseldonk, Edwin H.F.; Jensen, W.; Andersen, O.K.; Akay, M

2014-01-01

Transcranial direct current stimulation (tDCS) has been shown to improve force generation and control in single leg joints in healthy subjects and stroke survivors. However, it is unknown whether these effects also result in improved force production and coordination during walking. Here we

Brainstem tumors: Current management and future directions

Directory of Open Access Journals (Sweden)

Pablo F Recinos

2012-01-01

Full Text Available Tumors arising in the brainstem comprise 10-20% of all pediatric central nervous system (CNS tumors and account for a small percentage in adults. The prognosis for these tumors was considered uniformly poor prior to the era of modern neuroimaging and the location was fraught with disaster being considered a ′no man′s land′ for neurosurgeons. Following the introduction of advanced imaging modalities and neurophysiological monitoring, striking progress has occurred in the management of these lesions. Brainstem tumors are presently classified based on their anatomic location, focality, and histopathology. This article reviews the current classification of brainstem tumors, current management options, and future directions in the treatment for these rare tumors.

Transcranial direct current stimulation as a treatment for auditory hallucinations.

Directory of Open Access Journals (Sweden)

Sanne eKoops

2015-03-01

Full Text Available Auditory hallucinations (AH are a symptom of several psychiatric disorders, such as schizophrenia. In a significant minority of patients, AH are resistant to antipsychotic medication. Alternative treatment options for this medication-resistant group are scarce and most of them focus on coping with the hallucinations. Finding an alternative treatment that can diminish AH is of great importance.Transcranial direct current stimulation (tDCS is a safe and non-invasive technique that is able to directly influence cortical excitability through the application of very low electric currents. A 1-2 mA direct current is applied between two surface electrodes, one serving as the anode and the other as the cathode. Cortical excitability is increased in the vicinity of the anode and reduced near the cathode. The technique, which has only a few transient side effects and is cheap and portable, is increasingly explored as a treatment for neurological and psychiatric symptoms. It has shown efficacy on symptoms of depression, bipolar disorder, schizophrenia, Alzheimer’s disease, Parkinson’s disease, epilepsy and stroke. However, the application of tDCS as a treatment for AH is relatively new. This article provides an overview of the current knowledge in this field and provides guidelines for future research.

Current techniques for the collection and processing of stable isotope data

International Nuclear Information System (INIS)

Goodney, D.E.; Kroopnick, P.M.

1978-01-01

Recent innovations in instrumentation for stable isotope mass spectrometry are reviewed. 'Off-line' automatic data collection and 'on-line' processing systems have been developed for use with the Nuclide Integrating Ratiometer (IR-2). A BASIC program detects and corrects most instrumental and operator errors and performs all necessary computations. Analysis of the effects of source gas pressure on the accuracy of delta 18 O measurement showed that our Nuclide 3inch-60 0 instrument has a slope of -1.0 0 / 00 /volt over the normal operating range (10-30V), and our Nuclide 6inch-60 0 instrument has a slope of +0.6 0 / 00 /volt. Use of the IR-2 causes the apparent slopes to change to -1.45 0 / 00 /volt and +5 0 / 00 /volt for the 3inch and 6inch instruments, respectively.(auth.)

[The risk of direct current countershock].

Science.gov (United States)

Gajek, J; Zyśko, D

2001-07-01

Direct current cardioversion (DCC) is a procedure commonly used to restore the sinus rhythm in patients with supraventricular and ventricular arrhythmias. Its safety, regarding the use of electric current, is still a matter of controversy and debate. The patients with atrial fibrillation/flutter, supraventricular or ventricular tachycardia represent a broad spectrum of clinical conditions and it is difficult to draw the conclusions. The high success rate of DCC in restoring the sinus rhythm, may be partly responsible for enhancing and revealing proarrhythmic properties of antiarrhythmic drugs. The deaths described as a complications of DCC were mainly due to the proarrhythmia and less common to the progression of the pathologic process. The embolic, arrhythmic and anesthetic complications of DCC can be prevented if the known recommendations of performing the DCC are followed. The authors review critically the literature data about the complications of the procedure and come to the conclusion of safety of DCC.

Directed Motivational Currents: Using vision to create effective motivational pathways

Directory of Open Access Journals (Sweden)

Christine Muir

2013-10-01

Full Text Available Vision, that is, the mental representation of the sensory experience of a future goal state (involving imagination and imagery, is currently at the forefront of motivational innovation, and in recent years it has been seen increasingly more often in the motivational tool kit of practicing language teachers. Theories such as Dörnyei’s L2 motivational self system have explored the power that creating effective visions can harness (see, e.g., Dörnyei & Kubanyiova, 2014 and when viewed in conjunction with other current research avenues, such as future time perspective and dynamic systems theory, vision offers exciting potential. A Directed Motivational Current is a new motivational construct that we suggest is capable of integrating many current theoretical strands with vision: It can be described as a motivational drive which energises long-term, sustained behaviour (such as language learning, and through placing vision and goals as critical central components within this construct, it offers real and practical motivational potential. In this conceptual paper, we first discuss current understandings of vision and of Directed Motivational Currents, and then analyse how they may be optimally integrated and employed to create effective motivational pathways in language learning environments.

Analysis of electromagnetic field of direct action solenoid valve with current changing

International Nuclear Information System (INIS)

Liu Qianfeng; Bo Hanliang; Qin Benke

2009-01-01

Control rod hydraulic drive mechanism(CRHDM) is a newly invented patent of Institute of Nuclear and New Energy Technology of Tsinghua University. The direct action solenoid valve is the key part of this technology, so the performance of the solenoid valve directly affects the function of the CRHDM. With the current and the air gap changing,the electromagnetic field of the direct action solenoid valve was analyzed using the ANSYS software,which was validated by the experiment. The result shows that the electromagnetic force of the solenoid valve increases with the current increasing or the gap between the two armatures decreasing. Further more, the working current was confirmed. (authors)

Multiday Transcranial Direct Current Stimulation Causes Clinically Insignificant Changes in Childhood Dystonia: A Pilot Study.

Science.gov (United States)

Bhanpuri, Nasir H; Bertucco, Matteo; Young, Scott J; Lee, Annie A; Sanger, Terence D

2015-10-01

Abnormal motor cortex activity is common in dystonia. Cathodal transcranial direct current stimulation may alter cortical activity by decreasing excitability while anodal stimulation may increase motor learning. Previous results showed that a single session of cathodal transcranial direct current stimulation can improve symptoms in childhood dystonia. Here we performed a 5-day, sham-controlled, double-blind, crossover study, where we measured tracking and muscle overflow in a myocontrol-based task. We applied cathodal and anodal transcranial direct current stimulation (2 mA, 9 minutes per day). For cathodal transcranial direct current stimulation (7 participants), 3 subjects showed improvements whereas 2 showed worsening in overflow or tracking error. The effect size was small (about 1% of maximum voluntary contraction) and not clinically meaningful. For anodal transcranial direct current stimulation (6 participants), none showed improvement, whereas 5 showed worsening. Thus, multiday cathodal transcranial direct current stimulation reduced symptoms in some children but not to a clinically meaningful extent, whereas anodal transcranial direct current stimulation worsened symptoms. Our results do not support transcranial direct current stimulation as clinically viable for treating childhood dystonia. © The Author(s) 2015.

Direct calculation of current drive efficiency in FISIC code

International Nuclear Information System (INIS)

Wright, J.C.; Phillips, C.K.; Bonoli, P.T.

1996-01-01

Two-dimensional RF modeling codes use a parameterization (1) of current drive efficiencies to calculate fast wave driven currents. This parameterization assumes a uniform quasi-linear diffusion coefficient and requires a priori knowledge of the wave polarizations. These difficulties may be avoided by a direct calculation of the quasilinear diffusion coefficient from the Kennel-Englemann form with the field polarizations calculated by the full wave code, FISIC (2). Current profiles are calculated using the adjoint formulation (3). Comparisons between the two formulations are presented. copyright 1996 American Institute of Physics

The control of the upstream movement of fish with pulsated direct current

Science.gov (United States)

McLain, Alberton L.

1957-01-01

Alternating-current electromechanical devices installed in the mouths of streams have proved effective in stopping the spawning migrations of the parasitic sea lamprey (Petromyzon marinus) which has seriously damaged Great Lakes fisheries. In a few streams, excessive mortality has occurred to other fish at the alternating-current barriers. A direct-current unit was developed in an attempt to reduce this mortality. This direct-current “diversion device” consists of a row of suspended negative electrodes which begins at the end of a trap wing and extends across the river at a downstream angle of 45° and a series of pipes (positive electrodes) driven into the stream bank. A second array, consisting of horizontal pipes installed downstream and parallel to the suspended electrodes and connected to a series of rods driven into the bank near the positive electrodes, controls the electrical field and dissipates the collecting influence of the positive side of the circuit. The electrical field is established from the end of the trap wing to the opposite bank. Fish are diverted away from the negative electrodes and toward the bank near which the trap is located. The array is activiated by pulsated direct current of essentially square wave shape with pulses at a duty cycle of 0.66 and a repetition rate of 3 per second. Direct-current diversion devices were operated in conjunction with alternating-current barriers during 1956 in the Chocolay River, Marquette County, and the Silver River, Baraga County, Michigan.

Transcranial direct current stimulation for motor recovery of upper limb function after stroke.

Science.gov (United States)

Lüdemann-Podubecká, Jitka; Bösl, Kathrin; Rothhardt, Sandra; Verheyden, Geert; Nowak, Dennis Alexander

2014-11-01

Changes in neural processing after stroke have been postulated to impede recovery from stroke. Transcranial direct current stimulation has the potential to alter cortico-spinal excitability and thereby might be beneficial in stroke recovery. We review the pertinent literature prior to 30/09/2013 on transcranial direct current stimulation in promoting motor recovery of the affected upper limb after stroke. We found overall 23 trials (they included 523 participants). All stimulation protocols pride on interhemispheric imbalance model. In a comparative approach, methodology and effectiveness of (a) facilitation of the affected hemisphere, (b) inhibition of the unaffected hemisphere and (c) combined application of transcranial direct current stimulation over the affected and unaffected hemispheres to treat impaired hand function after stroke are presented. Transcranial direct current stimulation is associated with improvement of the affected upper limb after stroke, but current evidence does not support its routine use. Copyright © 2014 Elsevier Ltd. All rights reserved.

Current directions in radiopharmaceutical research

Energy Technology Data Exchange (ETDEWEB)

Mather, S J [Department of Nuclear Medicine, St. Bartholomew` s Hospital, London (United Kingdom)

1998-08-01

Much of current radiopharmaceutical research is directed towards the development of receptor-binding tracers which are targeted towards biochemical processes. These may be extra or intracellular in nature and hold promise for an imaging approach to tissue characterisation in-vivo. Many of these products are based on proteins which range in size from large monoclonal antibodies to small neuropeptides and share a radiolabelling chemistry based on the use of bifunctional chelating agents. Although developed initially for use with indium-111, considerations of cost and isotope availability have continued to direct the efforts of many researchers towards the use of technetium-99m. While polypeptide-based radiopharmaceuticals may be useful for imaging peripheral cell-surface receptors, access to sites of interest within the cell, or in the brain, requires the development of small lipophilic molecules with retained ability to interact with intracellular targets. The design and synthesis of these compounds presents a particular challenge to the radiopharmaceutical chemist which is being met through either a pendant or integrated approach to the use of technetium coordination with particular emphasis on technetium (v) cores. Progress continues to be made in the application of targeted radionuclide therapy particularly in the development of radiopharmaceuticals for the treatment of malignant bone disease. methods for labelling antibodies with a great variety of cytotoxic radionuclides have now been refined and their use for radioimmunotherapy in the treatment of haematological malignancies shows great promise. The major medical areas for application of these new radiopharmaceuticals will be in oncology, neurology and inflammation but the increasingly difficult regulatory climate in which drug development and health-care now operate will make it essential for researchers to direct their products toward specific clinical problems as well as biological targets. (author) 36 refs

Current directions in radiopharmaceutical research

International Nuclear Information System (INIS)

Mather, S.J.

1998-01-01

Much of current radiopharmaceutical research is directed towards the development of receptor-binding tracers which are targeted towards biochemical processes. These may be extra or intracellular in nature and hold promise for an imaging approach to tissue characterisation in-vivo. Many of these products are based on proteins which range in size from large monoclonal antibodies to small neuropeptides and share a radiolabelling chemistry based on the use of bifunctional chelating agents. Although developed initially for use with indium-111, considerations of cost and isotope availability have continued to direct the efforts of many researchers towards the use of technetium-99m. While polypeptide-based radiopharmaceuticals may be useful for imaging peripheral cell-surface receptors, access to sites of interest within the cell, or in the brain, requires the development of small lipophilic molecules with retained ability to interact with intracellular targets. The design and synthesis of these compounds presents a particular challenge to the radiopharmaceutical chemist which is being met through either a pendant or integrated approach to the use of technetium coordination with particular emphasis on technetium (v) cores. Progress continues to be made in the application of targeted radionuclide therapy particularly in the development of radiopharmaceuticals for the treatment of malignant bone disease. methods for labelling antibodies with a great variety of cytotoxic radionuclides have now been refined and their use for radioimmunotherapy in the treatment of haematological malignancies shows great promise. The major medical areas for application of these new radiopharmaceuticals will be in oncology, neurology and inflammation but the increasingly difficult regulatory climate in which drug development and health-care now operate will make it essential for researchers to direct their products toward specific clinical problems as well as biological targets. (author)

Current Direct Neutrino Mass Experiments

Directory of Open Access Journals (Sweden)

G. Drexlin

2013-01-01

Full Text Available In this contribution, we review the status and perspectives of direct neutrino mass experiments, which investigate the kinematics of β-decays of specific isotopes (3H, 187Re, 163Ho to derive model-independent information on the averaged electron (antineutrino mass. After discussing the kinematics of β-decay and the determination of the neutrino mass, we give a brief overview of past neutrino mass measurements (SN1987a-ToF studies, Mainz and Troitsk experiments for 3H, cryobolometers for 187Re. We then describe the Karlsruhe Tritium Neutrino (KATRIN experiment currently under construction at Karlsruhe Institute of Technology, which will use the MAC-E-Filter principle to push the sensitivity down to a value of 200 meV (90% C.L.. To do so, many technological challenges have to be solved related to source intensity and stability, as well as precision energy analysis and low background rate close to the kinematic endpoint of tritium β-decay at 18.6 keV. We then review new approaches such as the MARE, ECHO, and Project8 experiments, which offer the promise to perform an independent measurement of the neutrino mass in the sub-eV region. Altogether, the novel methods developed in direct neutrino mass experiments will provide vital information on the absolute mass scale of neutrinos.

Progress with helicity injection current drive

International Nuclear Information System (INIS)

Jarboe, T.R.; Raman, R.; Nelson, B.A.

2003-01-01

Coaxial Helicity Injection (CHI) experiments in the NSTX and HIT-II devices are reported. NSTX has produced toroidal currents of 0.4 MA and pulse lengths of up to 0.33 s. These discharges nearly fill the NSTX main chamber, and show the n=1 rotating distortion characteristic of high-performance CHI plasmas. CHI has been used in HIT-II to provide a closed flux startup plasma for inductive drive. The CHI startup method saves transformer volt-seconds and greatly improves reproducibility and reliability of inductively driven discharges, even in the presence of diminishing wall conditions. (author)

Direct-current-like Phase Space Manipulation Using Chirped Alternating Current Fields

International Nuclear Information System (INIS)

Schmit, P.F.; Fisch, N.J.

2010-01-01

Waves in plasmas can accelerate particles that are resonant with the wave. A dc electric field also accelerates particles, but without a resonance discrimination, which makes the acceleration mechanism profoundly different. Whereas wave-particle acceleration mechanisms have been widely discussed in the literature, this work discusses the direct analogy between wave acceleration and dc field acceleration in a particular parameter regime explored in previous works. Apart from the academic interest of this correspondence, there may be practical advantages in using waves to mimic dc electric fields, for example, in driving plasma current with high efficiency.

Obesity pharmacotherapy: current perspectives and future directions.

Science.gov (United States)

Misra, Monika

2013-02-01

The rising tide of obesity and its related disorders is one of the most pressing health concerns worldwide, yet existing medicines to combat the problem are disappointingly limited in number and effectiveness. Recent advances in mechanistic insights into the neuroendocrine regulation of body weight have revealed an expanding list of molecular targets for novel, rationally designed antiobesity pharmaceutical agents. Antiobesity drugs act via any of four mechanisms: 1) decreasing energy intake, 2) increasing energy expenditure or modulating lipid metabolism, 3) modulating fat stores or adipocyte differentiation, and 4) mimicking caloric restriction. Various novel drug candidates and targets directed against obesity are currently being explored. A few of them are also in the later phases of clinical trials. This review discusses the development of novel antiobesity drugs based on current understanding of energy homeostasis.

Experimental Study of Thermoelectric Generator as Electrical Source of Impressed Current Cathodic Protection for Ship Hull

Directory of Open Access Journals (Sweden)

Adi Kurniawan

2017-06-01

Full Text Available Impressed Current Cathodic Protection (ICCP is a method to protect metallic material such as ship hull from corrosion by using electric current. In this research, a prototype of thermoelectric generator is developed in order to supply the ICCP system. This thermoelectric generator is planned to utilize the exhaust gas from main engine of the ship. Method carried in this research is assembling the prototype of thermoelectric generator followed by conducted experiment to observe the potential energy of the prototype. After that, the required number of thermoelectric generator is calculated to supply the ICCP system to protect the ship from corrosion. The object in this research is live fish carrier “Wellboat” which has 396.08 m2 wetted area. The required voltage and current to protect the ship from corrosion for three years are 16.67 Volt and 2.66 Ampere. Based on the experiment, a prototype of thermoelectric generator can generate 0.34 Ampere and 4.43 Volt, causing the need of 8 series and 4 parallels connection. It can be concluded that the corrosion rate on the ship hull can be decelerated by using impressed current cathodic protection method without needing additional cost or fuel consumption to produce electric energy.  

Optimization of focality and direction in dense electrode array transcranial direct current stimulation (tDCS)

Science.gov (United States)

Guler, Seyhmus; Dannhauer, Moritz; Erem, Burak; Macleod, Rob; Tucker, Don; Turovets, Sergei; Luu, Phan; Erdogmus, Deniz; Brooks, Dana H.

2016-06-01

Objective. Transcranial direct current stimulation (tDCS) aims to alter brain function non-invasively via electrodes placed on the scalp. Conventional tDCS uses two relatively large patch electrodes to deliver electrical current to the brain region of interest (ROI). Recent studies have shown that using dense arrays containing up to 512 smaller electrodes may increase the precision of targeting ROIs. However, this creates a need for methods to determine effective and safe stimulus patterns as the number of degrees of freedom is much higher with such arrays. Several approaches to this problem have appeared in the literature. In this paper, we describe a new method for calculating optimal electrode stimulus patterns for targeted and directional modulation in dense array tDCS which differs in some important aspects with methods reported to date. Approach. We optimize stimulus pattern of dense arrays with fixed electrode placement to maximize the current density in a particular direction in the ROI. We impose a flexible set of safety constraints on the current power in the brain, individual electrode currents, and total injected current, to protect subject safety. The proposed optimization problem is convex and thus efficiently solved using existing optimization software to find unique and globally optimal electrode stimulus patterns. Main results. Solutions for four anatomical ROIs based on a realistic head model are shown as exemplary results. To illustrate the differences between our approach and previously introduced methods, we compare our method with two of the other leading methods in the literature. We also report on extensive simulations that show the effect of the values chosen for each proposed safety constraint bound on the optimized stimulus patterns. Significance. The proposed optimization approach employs volume based ROIs, easily adapts to different sets of safety constraints, and takes negligible time to compute. An in-depth comparison study gives

Outcomes in spasticity after repetitive transcranial magnetic and transcranial direct current stimulations

OpenAIRE

Gunduz, Aysegul; Kumru, Hatice; Pascual-Leone, Alvaro

2014-01-01

Non-invasive brain stimulations mainly consist of repetitive transcranial magnetic stimulation and transcranial direct current stimulation. Repetitive transcranial magnetic stimulation exhibits satisfactory outcomes in improving multiple sclerosis, stroke, spinal cord injury and cerebral palsy-induced spasticity. By contrast, transcranial direct current stimulation has only been studied in post-stroke spasticity. To better validate the efficacy of non-invasive brain stimulations in improving ...

Technology-based suicide prevention: current applications and future directions.

Science.gov (United States)

Luxton, David D; June, Jennifer D; Kinn, Julie T

2011-01-01

This review reports on current and emerging technologies for suicide prevention. Technology-based programs discussed include interactive educational and social networking Web sites, e-mail outreach, and programs that use mobile devices and texting. We describe innovative applications such as virtual worlds, gaming, and text analysis that are currently being developed and applied to suicide prevention and outreach programs. We also discuss the benefits and limitations of technology-based applications and discuss future directions for their use.

Method for exciting inductive-resistive loads with high and controllable direct current

International Nuclear Information System (INIS)

Hill, H.M. Jr.

1976-01-01

The apparatus and method for transmitting dc power to a load circuit by applying a dc voltage from a standard waveform synthesizer to duration modulate a bipolar rectangular wave generator are described. As the amplitude of the dc voltage increases, the widths of the rectangular wave generator output pulses increase, and as the amplitude of the dc voltage decreases, the widths of the rectangular wave generator output pulses decrease. Thus, the waveform synthesizer selectively changes the durations of the rectangular wave generator bipolar output pulses so as to produce a rectangular wave ac carrier that is duration modulated in accordance with and in direct proportion to the voltage amplitude from the synthesizer. Thereupon, by transferring the carrier to the load circuit through an amplifier and a rectifier, the load current also corresponds directly to the voltage amplitude from the synthesizer. To this end, the rectified wave at less than 100 percent duty factor amounts to a doubled frequency direct voltage pulse train for applying a direct current to the load, while the current ripple is minimized by a high L/R in the load circuit. In one embodiment, a power transmitting power amplifier means having a dc power supply is matched to the load circuit through a transformer for current magnification without sacrificing load current duration capability, while negative voltage and current feedback are provided in order to insure good output fidelity. 4 Claims, 18 Drawing Figures

Helicopter Rotor Noise Prediction: Background, Current Status, and Future Direction

Science.gov (United States)

Brentner, Kenneth S.

1997-01-01

Helicopter noise prediction is increasingly important. The purpose of this viewgraph presentation is to: 1) Put into perspective the recent progress; 2) Outline current prediction capabilities; 3) Forecast direction of future prediction research; 4) Identify rotorcraft noise prediction needs. The presentation includes an historical perspective, a description of governing equations, and the current status of source noise prediction.

Current direction, wind direction, temperature, and salinity data from moored current meter casts in the Gulf of Mexico during the Brine Disposal project, 01 February 1981 - 01 February 1981 (NODC Accession 8100516)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, temperature, wind direction, and salinity data were collected using moored current meter casts in the Gulf of Mexico from February 1, 1981 to...

Impact of transcranial direct current stimulation (tDCS) on neuronal functions

NARCIS (Netherlands)

Das, S. (Suman); P.J. Holland (Peter); M.A. Frens (Maarten); O. Donchin (Opher)

2016-01-01

textabstractTranscranial direct current stimulation (tDCS), a non-invasive brain stimulation technique, modulates neuronal excitability by the application of a small electrical current. The low cost and ease of the technique has driven interest in potential clinical applications. However, outcomes

Onsite-effects of dual-hemisphere versus conventional single-hemisphere transcranial direct current stimulation: A functional MRI study.

Science.gov (United States)

Kwon, Yong Hyun; Jang, Sung Ho

2012-08-25

We performed functional MRI examinations in six right-handed healthy subjects. During functional MRI scanning, transcranial direct current stimulation was delivered with the anode over the right primary sensorimotor cortex and the cathode over the left primary sensorimotor cortex using dual-hemispheric transcranial direct current stimulation. This was compared to a cathode over the left supraorbital area using conventional single-hemispheric transcranial direct current stimulation. Voxel counts and blood oxygenation level-dependent signal intensities in the right primary sensorimotor cortex regions were estimated and compared between the two transcranial direct current stimulation conditions. Our results showed that dual-hemispheric transcranial direct current stimulation induced greater cortical activities than single-hemispheric transcranial direct current stimulation. These findings suggest that dual-hemispheric transcranial direct current stimulation may provide more effective cortical stimulation than single-hemispheric transcranial direct current stimulation.

Analysis of critical thinking ability in direct current electrical problems solving

Science.gov (United States)

Hartono; Sunarno, Widha; Sarwanto; Arya Nugraha, Dewanta

2017-11-01

This study concern on analyzing the ability of students in critical thinking skills on the subject matter of direct current electricity. Samples were taken using purposive random sampling consisted of 32 students of grade XI, Multimedia 1, SMK Negeri 3 Surakarta in academic year 2016/2017. This study used descriptive quantitative method. The data were collected using tests and interviews regarding the subject matter of direct current electricity. Based on the results, students are getting some difficulties in solving problem in indicator 4. The average of students’ correct answer is 62.8%.

Revision of the Euratom basic safety standards directive-current status

International Nuclear Information System (INIS)

Mundig, S.

2011-01-01

The European Commission is currently developing a revised Euratom Basic Safety Standards (BSS) Directive covering two major objectives: the consolidation of existing Euratom Radiation Protection legislation and the revision of the Euratom BSS. The consolidation will merge the following five Directives into one single Directive: the BSS Directive, the Medical Exposures Directive, the Public Information Directive, the Outside Workers Directive and the Directive on the Control of high-activity sealed radioactive sources and orphan sources. The revision of the Euratom BSS will take account of the latest recommendations by the International Commission on Radiological Protection and shall improve clarity of the requirements where appropriate. It is planned to introduce more binding requirements on natural radiation sources, on criteria for exemption and clearance, and on the cooperation between Member States for emergency planning and response. The provisions for regulatory control of planned exposure situations foresee a graded approach commensurate to the magnitude and likelihood of exposures from a practice. Finally, the new BSS shall take account of recent scientific developments. One additional goal is to achieve greater harmonisation between the Euratom BSS and the international BSS. While the requirements on the protection of workers, apprentices and students remain nearly unchanged, the revised BSS will clarify the roles and responsibilities of services and experts involved in technical and practical aspects of radiation protection, such as the occupational health services, the dosimetry services, the radiation protection expert and the medical physics expert. The requirements in the BSS on individual monitoring of category A workers remain unchanged, but the existing guidance on individual monitoring was revised and updated-the technical recommendations for monitoring individuals occupationally exposed to external radiation are published by the European

Novel methods to optimize the effects of transcranial direct current stimulation: a systematic review of transcranial direct current stimulation patents.

Science.gov (United States)

Malavera, Alejandra; Vasquez, Alejandra; Fregni, Felipe

2015-01-01

Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that has been extensively studied. While there have been initial positive results in some clinical trials, there is still variability in tDCS results. The aim of this article is to review and discuss patents assessing novel methods to optimize the use of tDCS. A systematic review was performed using Google patents database with tDCS as the main technique, with patents filling date between 2010 and 2015. Twenty-two patents met our inclusion criteria. These patents attempt to address current tDCS limitations. Only a few of them have been investigated in clinical trials (i.e., high-definition tDCS), and indeed most of them have not been tested before in human trials. Further clinical testing is required to assess which patents are more likely to optimize the effects of tDCS. We discuss the potential optimization of tDCS based on these patents and the current experience with standard tDCS.

The morphological and molecular changes of brain cells exposed to direct current electric field stimulation.

Science.gov (United States)

Pelletier, Simon J; Lagacé, Marie; St-Amour, Isabelle; Arsenault, Dany; Cisbani, Giulia; Chabrat, Audrey; Fecteau, Shirley; Lévesque, Martin; Cicchetti, Francesca

2014-12-07

The application of low-intensity direct current electric fields has been experimentally used in the clinic to treat a number of brain disorders, predominantly using transcranial direct current stimulation approaches. However, the cellular and molecular changes induced by such treatment remain largely unknown. Here, we tested various intensities of direct current electric fields (0, 25, 50, and 100V/m) in a well-controlled in vitro environment in order to investigate the responses of neurons, microglia, and astrocytes to this type of stimulation. This included morphological assessments of the cells, viability, as well as shape and fiber outgrowth relative to the orientation of the direct current electric field. We also undertook enzyme-linked immunosorbent assays and western immunoblotting to identify which molecular pathways were affected by direct current electric fields. In response to direct current electric field, neurons developed an elongated cell body shape with neurite outgrowth that was associated with a significant increase in growth associated protein-43. Fetal midbrain dopaminergic explants grown in a collagen gel matrix also showed a reorientation of their neurites towards the cathode. BV2 microglial cells adopted distinct morphological changes with an increase in cyclooxygenase-2 expression, but these were dependent on whether they had already been activated with lipopolysaccharide. Finally, astrocytes displayed elongated cell bodies with cellular filopodia that were oriented perpendicularly to the direct current electric field. We show that cells of the central nervous system can respond to direct current electric fields both in terms of their morphological shape and molecular expression of certain proteins, and this in turn can help us to begin understand the mechanisms underlying the clinical benefits of direct current electric field. © The Author 2015. Published by Oxford University Press on behalf of CINP.

Pulse width modulated buck-boost five-level current source inverters

DEFF Research Database (Denmark)

Blaabjerg, Frede; Gao, F.; Loh, P.C.

2008-01-01

, resulting in the natural balance of input current. For maintaining the normalized volt-sec average unchanged, the alternative phase opposition disposition (APOD) modulation scheme with typical gating signal mapping technique from voltage source inverter (VSI) to CSI can be assumed to control the five......This paper presents new five-level current source inverters (CSIs) with voltage/current buck-boost capability. Being different from the existing multilevel CSI, the proposed CSIs were first designed to regulate the flowing path of dc input current by controlling two additional active switches......-level buck-boost CSIs. Next by observing the hidden current charging path during inductive charging interval under APOD modulation, it is noted that the buck-boost five-level CSI can then be further modified with lesser active component without degrading output performance. To verify the theoretical findings...

Effects of Transcranial Direct Current Stimulation on Expression of Immediate Early Genes (IEG’s)

Science.gov (United States)

2015-12-01

TRANSCRANIAL DIRECT CURRENT STIMULATION OF EXPRESSION OF IMMEDIATE EARLY GENES (IEG’S) Jessica...AND SUBTITLE Effects of Transcranial Direct Current Stimulation on Expression of Immediate Early Genes (IEG’s) 5a. CONTRACT NUMBER In-House 5b...community in better understanding what is occurring biologically during tDCS. 15. SUBJECT TERMS Transcranial direct current stimulation

Feasibility of transcranial direct current stimulation use in children aged 5 to 12 years.

Science.gov (United States)

Andrade, Agnes Carvalho; Magnavita, Guilherme Moreira; Allegro, Juleilda Valéria Brasil Nunes; Neto, Carlos Eduardo Borges Passos; Lucena, Rita de Cássia Saldanha; Fregni, Felipe

2014-10-01

Transcranial direct current stimulation is a noninvasive brain stimulation technique that has been studied for the treatment of neuropsychiatric disorders in adults, with minimal side effects. The objective of this study is to report the feasibility, tolerability, and the short-term adverse effects of transcranial direct current stimulation in children from 5 to 12 years of age. It is a naturalistic study of 14 children who underwent 10 sessions of transcranial direct current stimulation as an alternative, off-label, and open-label treatment for various languages disorders. Frequency, intensity, adverse effects, and perception of improvement reported by parents were collected. The main side effects detected were tingling (28.6%) and itching (28.6%), acute mood changes (42.9%), and irritability (35.7%). Transcranial direct current stimulation is a feasible and tolerable technique in children, although studies regarding plastic and cognitive changes in children are needed to confirm its safety. In conclusion, this is a naturalistic report in which we considered transcranial direct current stimulation as feasible in children. © The Author(s) 2013.

Current direction, benthic organisms, temperature, and wind direction data from moored current meter casts in the Gulf of Mexico during the Brine Disposal project, 22 September 1977 - 30 November 1978 (NODC Accession 7900110)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, benthic organisms, temperature, and wind direction data were collected using moored current meter casts in the Gulf of Mexico from September 22,...

Reclaiming Saline-Sodic Soils Using Electrochemical Processes: A Case Study From Sahl El-Tina Plain, Egypt

Directory of Open Access Journals (Sweden)

Abdel-Fattah Mohamed K.

2014-10-01

Full Text Available A leaching experiment was conducted using column techniques assessing efficiency of electrochemical process to reclaim saline-sodic soils. Soil material was collected from Sahl El-Tina plain, which located in North West coast of Sinai, Egypt. The experiment was designed as factorial randomized complete block and all treatments were replicated three times. Two 2.5 cm diameterx30 cm height mild stainless steel tubes were inserted into the soil matrix to serve as electrodes (i.e. cathode and anode. Distance between cathode and anode was 10 cm. Electrodes were supplied by a direct current (DC power supply; Volt ages of 0.3 or 9 Volt. Leaching was done using the intermittent method so as to add portions to the already saturated soil columns, and obtain leachates equal to the added portions. Pore volume 0.1 PV was used in the leaching processes which are equal 498.4 cm3, i.e. PV being volume of pores per column, thus 1 PV equals volume of pores (cm3 expressed as water quantity. Electric remediation increased ionic mobility and separated salts from soil. All treatments decreased soil EC and soil sodicity expressed as SAR and ESP. Results showed that 9 Volt treatment was more effective in decreasing the soil EC and soil sodicity than the other treatments. Efficiency of treatments were 9-Volt > 3-Volt > leaching alone (non-DC treatment. This study suggests that leaching using direct current (DC led to improvement of the chemical properties of saline sodic soils and required a short time to reclaim saline-sodic soils compared with leaching alone.

Transcranial Direct Current Stimulation Does Not Improve Language Outcome in Subacute Poststroke Aphasia.

Science.gov (United States)

Spielmann, Kerstin; van de Sandt-Koenderman, W Mieke E; Heijenbrok-Kal, Majanka H; Ribbers, Gerard M

2018-04-01

The aim of the present study is to investigate the effect of transcranial direct current stimulation on word-finding treatment outcome in subacute poststroke aphasia. In this multi-center, double-blind, randomized controlled trial with 6-month follow-up, we included 58 patients with subacute aphasia (transcranial direct current stimulation (1 mA, 20 minutes; experimental group) or sham transcranial direct current stimulation (control group) over the left inferior frontal gyrus. The primary outcome measure was the Boston Naming Test. Secondary outcome measures included naming performance for trained/untrained picture items and verbal communication. Both the experimental (n=26) and the control group (n=32) improved on the Boston Naming Test over the intervention period and 6-month follow-up; however, there were no significant differences between groups. Also for the secondary outcome measures, no significant differences were found. The results of the present study do not support an effect of transcranial direct current stimulation as an adjuvant treatment in subacute poststroke aphasia. URL: http://www.trialregister.nl/trialreg/admin/rctview.asp. Unique identifier: NTR4364. © 2018 American Heart Association, Inc.

Directed Current Without Dissipation: Reincarnation of a Maxwell-Loschmidt Demon

Science.gov (United States)

Goychuk, Igor; Haenggi, Peter

We investigate whether for initially localized particles a directed current in rocked periodic structures is possible in absence of a dissipative mechanism. With a pure Hamiltonian dynamics the breaking of Time-Reversal-Invariante presents anecessary condition to find nonzero current values. Numerical studies are presented for the classical Hamiltonian dynamical case. These support the fact that indeed a finite current does occur when a time-reversal symmetry-breaking signal, such as a harmonic mixing signal, is acting. To gain analytical insight we consider the coherent driven quantum transport in a one-dimensional tight-binding lattice. Here, a finite coherent current is absent for initially localized preparations; it emerges, however, when the initial preparation (with zero initial current) possesses finite coherence. The presence of phase fluctuations will eventually kill any finite current, thereby rendering the nondissipative currents a transient phenomenon.

Regimes of magnetic insulation in a high-current diodes and transmission lines of conical configuration

International Nuclear Information System (INIS)

Vasilenko, O.I.; Voronin, V.S.; Lebedev, A.N.

1977-01-01

A self-consistent kinematic model of a steady-state electron flow between two electrodes of a high-current diode has been considered with a tapered configuration. All the electrons have presumably been released from the cathode with a zero velocity and some portion of the total current flows along the cathode surface as the conduction current. A set of volt-ampere characteristics has been obtained for the tapered diode with a flat anode. At a preset cathode current the thickness and current of the electron layer increase as the voltage goes up. The considered kinematic model substantiates and specifies a model of the Brillouin parapotential flow

Current status and future direction of the MONK software package

International Nuclear Information System (INIS)

Smith, Nigel; Armishaw, Malcolm; Cooper, Andrew

2003-01-01

The current status of the MONK criticality software package is summarized in terms of recent and current developments and envisaged directions for the future. The areas of the discussion are physics modeling, geometry modeling, source modeling, nuclear data, validation, supporting tools and customer services. In future development plan, MONK continues to be focused on meeting the short and long-term needs of the code user community. (J.P.N.)

The Analysis of Structure and Type of Narration in Nasserkhosrow’s Travelogue based on Zheplint Volt’s Theory

Directory of Open Access Journals (Sweden)

m Mohammadi Fesharaki

2013-11-01

Full Text Available How and to what extent the narrative structure of Nasserkhosrow travelogue can participate in reflecting the thoughts and creating a literary-narrative framework? Why is the structure of Nasserkhosrow travelogue similar to a story plot? And based on Zheplint Volt’s theory, what is the narrative type of Nasserkhosrow travelogue? A unique feature of Nasserkhosrow travelogue, unlike other travelogues, is that it begins with a fictional event and has narrative-literary language, pleasant tales, carefulness and description. Although the overall structure of travelogue is different from stories and novels, this travelogue is more similar to stories than travelogues and reports due to unique narrative and structural reasons. Many structural features of story such as initial state, destructive force, middle state and final phase, have given a different structure to this travelogue. In addition to these unique narrative types, this work can easily attract the addressees. This research tries to analyze the plot structure and narrative type in Nasserkhosrow travelogue based on modern narrative approach of Zheplint Volt. Accordingly, our results show that he has used similar narrative pattern (narrator=character and two internal and zero points of view to express his travel experiences.

Design and Control of an Inverter for Photovoltaic Applications

DEFF Research Database (Denmark)

Kjær, Søren Bækhøj

The energy demand in the world is steadily increasing and new types of energy sources must be found in order to cover the future demands, since the conventional sources are about to be emptied. One type of renewable energy source is the photovoltaic (PV) cell, which converts sunlight to electrical...... current, without any form for mechanical or thermal interlink. PV cells are usually connected together to make PV modules, consisting of 72 PV cells, which generates a DC voltage between 23 Volt to 45 Volt and a typical maximum power of 160 Watt, depending on temperature and solar irradiation....... The electrical infrastructure around the world is based on AC voltage, with a few exceptions, with a voltage of 120 Volt or 230 Volt in the distribution grid. PV modules can therefore not be connected directly to the grid, but must be connected through an inverter. The two main tasks for the inverter are to load...

Investigation of in vitro bone cell adhesion and proliferation on Ti using direct current stimulation

International Nuclear Information System (INIS)

Bodhak, Subhadip; Bose, Susmita; Kinsel, William C.; Bandyopadhyay, Amit

2012-01-01

Our objective was to establish an in vitro cell culture protocol to improve bone cell attachment and proliferation on Ti substrate using direct current stimulation. For this purpose, a custom made electrical stimulator was developed and a varying range of direct currents, from 5 to 25 μA, was used to study the current stimulation effect on bone cells cultured on conducting Ti samples in vitro. Cell–material interaction was studied for a maximum of 5 days by culturing with human fetal osteoblast cells (hFOB). The direct current was applied in every 8 h time interval and the duration of electrical stimulation was kept constant at 15 min for all cases. In vitro results showed that direct current stimulation significantly favored bone cell attachment and proliferation in comparison to nonstimulated Ti surface. Immunochemistry and confocal microscopy results confirmed that the cell adhesion was most pronounced on 25 μA direct current stimulated Ti surfaces as hFOB cells expressed higher vinculin protein with increasing amount of direct current. Furthermore, MTT assay results established that cells grew 30% higher in number under 25 μA electrical stimulation as compared to nonstimulated Ti surface after 5 days of culture period. In this work we have successfully established a simple and cost effective in vitro protocol offering easy and rapid analysis of bone cell–material interaction which can be used in promotion of bone cell attachment and growth on Ti substrate using direct current electrical stimulation in an in vitro model. - Highlights: ► D.C. stimulation was used to enhance in vitro bone cell adhesion and proliferation. ► Cells cultured on Ti were stimulated by using a custom made electrical stimulator. ► Optimization was performed by using a varying range of direct currents ∼ 5 to 25 μA. ► 25 μA stimulation was found most beneficial for promotion of cell adhesion/growth.

Innovations in electrophoretic deposition: Alternating current and pulsed direct current methods

International Nuclear Information System (INIS)

Chávez-Valdez, Alejandra; Boccaccini, Aldo R.

2012-01-01

This review summarizes emerging developments in the field of alternating current (AC) and pulsed direct current (DC) electrophoretic deposition (EPD) in aqueous or organic media. Numerous applications of AC-EPD are discussed including two major groups of investigations: (i) AC-EPD to suppress water hydrolysis at high voltages in inorganic (ceramic) coatings and (ii) AC-EPD for deposition of biological entities. The deposition, purification and manipulation of carbon nanotubes and nanoparticles by AC-EPD to form specific arrays, for development of sensors and other electronic devices and the application of AC-EPD as method for separation of particles according to their shape or size are also presented. Other applications reviewed relate to the fabrication by AC-EPD of toxic gas sensors from oxides and superconducting layers. The main materials being examined by AC-EPD are inorganic, including carbon nanotubes, TiO 2 nanoparticles, Al 2 O 3 , Si, SnO 2 , ZnO and WO 3 and biological entities, e.g. bacteria cells. For pulsed EPD, the applications reviewed are divided in pulsed current and pulsed voltage EPD. Among the applications of pulsed EPD, the formation of thick films from aqueous suspensions without water decomposition, the fabrication of multilayer and composite materials and the size-selective deposition of ceramic nanoparticles are the most important investigated to date, based on the quality of the coatings and deposits obtained and their relevance for applications.

HIV vaccines: current challenges and future directions.

Science.gov (United States)

Avrett, Sam; Collins, Chris

2002-07-01

Volume seven of the Review will mark the tenth anniversary of the Canadian HIV/AIDS Legal Network with a series of articles that describe past developments and future directions in several areas of policy and law related to HIV/AIDS. The following article is the first of these, discussing current challenges and future directions in the development of and access to HIV vaccines. It argues that governments are under public health, ethical, and legal obligations to develop and provide access to HIV vaccines. It further explains what is required for governments to fulfill their obligations: additional commitment and resources for HIV vaccine development in the context of increased global research and development regarding diseases of the poor; increased support and advocacy for partnerships to develop HIV vaccines; enhanced regulatory capacity in every country to review, approve, and monitor HIV vaccines; and assurance of global supply of, procurement of, delivery of, and access to vaccines in the context of efforts to increase global access to public health measures and technologies.

The Breakdown Mechanisms In Electrical Discharges: The Role Of The Field Emission Effect In Direct Current Discharges In Micro gaps

International Nuclear Information System (INIS)

Radmilovic-Radjenovic, M.; Radjenovic, B.; Bojarov, A.; Klas, M.; Matejcik, S.

2013-01-01

This review represents an attempt to sum up the current state of the research in the field of breakdown phenomena in electrical discharges. The paper provides facts and theories concerning different classes of direct current, radio and microwave frequency discharges, in vacuum, in the gas and in liquids, without and in the presence of the magnetic fields. The emphasize was made on the field emission effects and on the fundamental aspects of the breakdown phenomena in micro discharges via discussions and analysis of the experimental, theoretical and simulation results. It was found that the Paschen's law is not applicable for the micron gap sizes, when deviations from the standard scaling law become evident and modified Paschen curve should be used. The explanation of the deviations from the Paschen law was attributed to the secondary electron emission enhanced by the strong field generated in micro gaps. The experiments were carried out in order to establish scaling law in micro gaps. The volt-ampere characteristics were also recorded and compared with the theoretical predictions based on the Fowler-Nordheim theory. The importance of the enhancement factor and the space charge on results was also considered. On the basis of the experimental breakdown voltage curves, the effective yields in micro gaps have been estimated for different gases which can be served as input data in modeling. The effective yields allow analytically produce modified Paschen curves that predicts the deviations from the Paschen law observed in the experiments. In addition, we present results of computer simulations using a Particle-in-cell/Monte Carlo Collisions (PIC/MCC) code with the secondary emission model in order to include the field emission enhanced secondary electron production in micro gaps. The agreement between simulation and experimental results suggest that computer simulations can be used to improve understanding of the plasma physics as an alternative to analytical

High current transistor pulse generator

International Nuclear Information System (INIS)

Nesterov, V.; Cassel, R.

1991-05-01

A solid state pulse generator capable of delivering high current trapezoidally shaped pulses into an inductive load has been developed at SLAC. Energy stored in the capacitor bank of the pulse generator is switched to the load through a pair of Darlington transistors. A combination of diodes and Darlington transistors is used to obtain trapezoidal or triangular shaped current pulses into an inductive load and to recover the remaining energy in the same capacitor bank without reversing capacitor voltage. The transistors work in the switch mode, and the power losses are low. The rack mounted pulse generators presently used at SLAC contain a 660 microfarad storage capacitor bank and can deliver 400 amps at 800 volts into inductive loads up to 3 mH. The pulse generators are used in several different power systems, including pulse to pulse bipolar power supplies and in application with current pulses distributed into different inductive loads. The current amplitude and discharge time are controlled by the central computer system through a specially developed multichannel controller. Several years of operation with the pulse generators have proven their consistent performance and reliability. 8 figs

30 CFR 75.703-3 - Approved methods of grounding offtrack mobile, portable and stationary direct-current machines.

Science.gov (United States)

2010-07-01

..., portable and stationary direct-current machines. 75.703-3 Section 75.703-3 Mineral Resources MINE SAFETY... stationary direct-current machines. In grounding offtrack direct-current machines and the enclosures of their... requirements: (1) Installation of silicon diodes shall be restricted to electric equipment receiving power from...

Compulsory Checking of Nuclear Power Engineering Materials by Direct and Eddy Current

Science.gov (United States)

Larionov, V. V.; Lider, A. M.; Sednev, D. A.; Xu, Shupeng

2016-08-01

The testing technology of copper parts designed for dry storage of spent nuclear fuel with application of direct and eddy current has been developed. Measurements results of flaw quantity caused hydrogenation and oxidation processes are presented. Evolution of copper M 001 flaw structure during hydrogenation from gaseous medium is analyzed. It has been demonstrated that the dependence of copper p electrical resistance on number of flaws in its structure has dome shaped character and changes with eddy current frequency change. Number of flaws formed by hydrogen depends on direction (100) or (200) of the crystal structure of copper lattice.

Dependence of critical current density on crystalline direction in thin YBCO films

DEFF Research Database (Denmark)

Paturi, P.; Peurla, M.; Raittila, J.

2005-01-01

The dependence of critical current density (J(c)) on the angle between the current direction and the (100) direction in the ab-plane of thin YBCO films deposited on (001)-SrTiO3 from natiocrystalline and microcrystalline targets is studied using magneto-optical microscopy. In the films made from...... the nanocrystalline target it is found that J(c) does not depend on the angle whereas J(c) decreases with increasing angle in the films made from the microcrystalline target. The films were characterized by detailed X-ray diffraction measurements. The findings are explained in terms of a network of planar defects...

Efficacy of low level electric current (A-C) for controlling quagga mussles in the Welland Canal

Energy Technology Data Exchange (ETDEWEB)

Fears, C. [Delta Applied Technology, Inc., Pittsburgh, PA (United States); Mackie, G.L. [Water Systems Analysts, Guelph, Ontario (Canada)

1995-06-01

The efficacy of systems (for which patents are pending) which use low-voltage A-C currents for preventing settlement and attachment by zebra mussels were tested with steel rods and plates placed near the intake of a pulp and paper plant in the Welland Canal at Thorold, Ontario. Six racks made of 16 ft. (4.9 m), 2x4s (5.1 x 10.2 cm) were placed into the Welland Canal on August 5, 1994. One rack had 1/8th in (3.2 mm) diam x 12 in (30.5 cm) long steel rods, each separated by 2 in (5.1 cm) attached to pressure treated wood and concrete blocks and an A-C current of 16 v (or 8 v/in); rack 2 had steel rods of the same configuration but 12 v (or 6 v/in) was applied; rack 3 was identical to these but no current was applied and was used as a rod control. The remaining three racks had steel plates, each plate being 3 in (7.6 cm) wide X 24 in (61 cm) long X 1/4 in (6.4 mm) thick and separated by 2 in (5.1 cm); one had 12 v applied (or 6 v/in), another had 16 v applied (or 8 v/in), and the third had no current and was used as a plate control. The racks were placed on the upstream and downstream side of the intake at a depth of about 7 ft (2.1 m) where the mussels populations were heaviest (as determined by SCUBA diving). All mussels were quagga mussels (Dreissena bugensis). The racks were pulled in mid November after settlement was complete and the results showed: (1) complete prevention of settlement of both new recruits and translocators at 8 volts/in with steel rods on both wood and concrete surfaces and with steel plate trash bars; (2) partial prevention of settlement at 6 volts/in with steel rods on both wood and concrete surfaces and steel plates; and (3) that, at current kilowatt hr rates, total efficacy at 8 volts/in would cost approximately $10.80/day/1000 sq ft using rods to protect concrete walls and about $16.32/day/1000 sq ft to protect 3 in wide x 1/4 in thick trash bars. These costs can be reduced even further with pulse dosed AC currents.

High-voltage direct-current circuit breakers

International Nuclear Information System (INIS)

Yoshioka, Y.; Hirasawa, K.

1991-01-01

This paper reports that in 1954 the first high-voltage direct-current (HVDC) transmission system was put into operation between Gotland and the mainland of Sweden. Its system voltage and capacity were 100 kV and 20 MW, respectively. Since then many HVDC transmission systems have been planned, constructed, or commissioned in more than 30 places worldwide, and their total capacity is close to 40 GW. Most systems commissioned to date are two-terminal schemes, and HVDC breakers are not yet used in the high-potential main circuit of those systems, because the system is expected to perform well using only converter/inverter control even at a fault stage of the transmission line. However, even in a two-terminal scheme there are not a few merits in using an HVDC breaker when the system has two parallel transmission lines, that is, when it is a double-circuit system

Safety of Transcranial Direct Current Stimulation: Evidence Based Update 2016.

Science.gov (United States)

Bikson, Marom; Grossman, Pnina; Thomas, Chris; Zannou, Adantchede Louis; Jiang, Jimmy; Adnan, Tatheer; Mourdoukoutas, Antonios P; Kronberg, Greg; Truong, Dennis; Boggio, Paulo; Brunoni, André R; Charvet, Leigh; Fregni, Felipe; Fritsch, Brita; Gillick, Bernadette; Hamilton, Roy H; Hampstead, Benjamin M; Jankord, Ryan; Kirton, Adam; Knotkova, Helena; Liebetanz, David; Liu, Anli; Loo, Colleen; Nitsche, Michael A; Reis, Janine; Richardson, Jessica D; Rotenberg, Alexander; Turkeltaub, Peter E; Woods, Adam J

2016-01-01

This review updates and consolidates evidence on the safety of transcranial Direct Current Stimulation (tDCS). Safety is here operationally defined by, and limited to, the absence of evidence for a Serious Adverse Effect, the criteria for which are rigorously defined. This review adopts an evidence-based approach, based on an aggregation of experience from human trials, taking care not to confuse speculation on potential hazards or lack of data to refute such speculation with evidence for risk. Safety data from animal tests for tissue damage are reviewed with systematic consideration of translation to humans. Arbitrary safety considerations are avoided. Computational models are used to relate dose to brain exposure in humans and animals. We review relevant dose-response curves and dose metrics (e.g. current, duration, current density, charge, charge density) for meaningful safety standards. Special consideration is given to theoretically vulnerable populations including children and the elderly, subjects with mood disorders, epilepsy, stroke, implants, and home users. Evidence from relevant animal models indicates that brain injury by Direct Current Stimulation (DCS) occurs at predicted brain current densities (6.3-13 A/m(2)) that are over an order of magnitude above those produced by conventional tDCS. To date, the use of conventional tDCS protocols in human trials (≤40 min, ≤4 milliamperes, ≤7.2 Coulombs) has not produced any reports of a Serious Adverse Effect or irreversible injury across over 33,200 sessions and 1000 subjects with repeated sessions. This includes a wide variety of subjects, including persons from potentially vulnerable populations. Copyright © 2016 Elsevier Inc. All rights reserved.

High-temperature performance of MoS{sub 2} thin-film transistors: Direct current and pulse current-voltage characteristics

Energy Technology Data Exchange (ETDEWEB)

Jiang, C.; Samnakay, R.; Balandin, A. A., E-mail: balandin@ee.ucr.edu [Nano-Device Laboratory (NDL), Department of Electrical Engineering, Bourns College of Engineering, University of California—Riverside, Riverside, California 92521 (United States); Phonon Optimized Engineered Materials (POEM) Center, Materials Science and Engineering Program, University of California—Riverside, Riverside, California 92521 (United States); Rumyantsev, S. L. [Department of Electrical, Computer, and Systems Engineering, Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Ioffe Physical-Technical Institute, St. Petersburg 194021 (Russian Federation); Shur, M. S. [Department of Electrical, Computer, and Systems Engineering, Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

2015-02-14

We report on fabrication of MoS{sub 2} thin-film transistors (TFTs) and experimental investigations of their high-temperature current-voltage characteristics. The measurements show that MoS{sub 2} devices remain functional to temperatures of at least as high as 500 K. The temperature increase results in decreased threshold voltage and mobility. The comparison of the direct current (DC) and pulse measurements shows that the direct current sub-linear and super-linear output characteristics of MoS{sub 2} thin-films devices result from the Joule heating and the interplay of the threshold voltage and mobility temperature dependences. At temperatures above 450 K, a kink in the drain current occurs at zero gate voltage irrespective of the threshold voltage value. This intriguing phenomenon, referred to as a “memory step,” was attributed to the slow relaxation processes in thin films similar to those in graphene and electron glasses. The fabricated MoS{sub 2} thin-film transistors demonstrated stable operation after two months of aging. The obtained results suggest new applications for MoS{sub 2} thin-film transistors in extreme-temperature electronics and sensors.

Transcranial direct-current stimulation as treatment in epilepsy.

Science.gov (United States)

Gschwind, Markus; Seeck, Margitta

2016-12-01

Neuromodulation (NM) is a complementary therapy for patients with drug-resistant epilepsy. Vagal nerve stimulation and deep brain stimulation of the anterior thalamus are established techniques and have shown their efficacy in lowering seizure frequency, but they are invasive and rarely render patients seizure-free. Non-invasive NM techniques are therefore increasingly investigated in a clinical context. Areas covered: Current knowledge about transcranial direct-current stimulation (tDCS) and other non-invasive NM in patients with epilepsy, based on the available animal and clinical studies from PubMed search. Expert commentary: tDCS modulates neuronal membrane potentials, and consequently alters cortical excitability. Cathodal stimulation leads to cortical inhibition, which is of particular importance in epilepsy treatment. The antiepileptic efficacy is promising but still lacks systematic studies. The beneficial effect, seen in ~20%, outlasts the duration of stimulation, indicating neuronal plasticity and is therefore of great interest to obtain long-term effects.

Direct-current nanogenerator driven by ultrasonic waves.

Science.gov (United States)

Wang, Xudong; Song, Jinhui; Liu, Jin; Wang, Zhong Lin

2007-04-06

We have developed a nanowire nanogenerator that is driven by an ultrasonic wave to produce continuous direct-current output. The nanogenerator was fabricated with vertically aligned zinc oxide nanowire arrays that were placed beneath a zigzag metal electrode with a small gap. The wave drives the electrode up and down to bend and/or vibrate the nanowires. A piezoelectric-semiconducting coupling process converts mechanical energy into electricity. The zigzag electrode acts as an array of parallel integrated metal tips that simultaneously and continuously create, collect, and output electricity from all of the nanowires. The approach presents an adaptable, mobile, and cost-effective technology for harvesting energy from the environment, and it offers a potential solution for powering nanodevices and nanosystems.

Cerebellar transcranial direct current stimulation in patients with ataxia: A double-blind, randomized, sham-controlled study.

Science.gov (United States)

Benussi, Alberto; Koch, Giacomo; Cotelli, Maria; Padovani, Alessandro; Borroni, Barbara

2015-10-01

Numerous studies have highlighted the possibility of modulating the excitability of cerebellar circuits using transcranial direct current stimulation. The present study investigated whether a single session of cerebellar anodal transcranial direct current stimulation could improve symptoms in patients with ataxia. Nineteen patients with ataxia underwent a clinical and functional evaluation pre- and post-double-blind, randomized, sham, or anodal transcranial direct current stimulation. There was a significant interaction between treatment and time on the Scale for the Assessment and Rating of Ataxia, on the International Cooperative Ataxia Rating Scale, on the 9-Hole Peg Test, and on the 8-Meter Walking Time (P transcranial direct current stimulation can transiently improve symptoms in patients with ataxia and might represent a promising tool for future rehabilitative approaches. © 2015 International Parkinson and Movement Disorder Society.

Modelling the effect of electrode displacement on transcranial direct current stimulation (tDCS)

Science.gov (United States)

Ramaraju, Sriharsha; Roula, Mohammed A.; McCarthy, Peter W.

2018-02-01

Objective. Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that delivers a low-intensity, direct current to cortical areas with the purpose of modulating underlying brain activity. Recent studies have reported inconsistencies in tDCS outcomes. The underlying assumption of many tDCS studies has been that replication of electrode montage equates to replicating stimulation conditions. It is possible however that anatomical difference between subjects, as well as inherent inaccuracies in montage placement, could affect current flow to targeted areas. The hypothesis that stimulation of a defined brain region will be stable under small displacements was tested. Approach. Initially, we compared the total simulated current flowing through ten specific brain areas for four commonly used tDCS montages: F3-Fp2, C3-Fp2, Fp1-F4, and P3-P4 using the software tool COMETS. The effect of a slight (~1 cm in each of four directions) anode displacement on the simulated regional current density for each of the four tDCS montages was then determined. Current flow was calculated and compared through ten segmented brain areas to determine the effect of montage type and displacement. The regional currents, as well as the localised current densities, were compared with the original electrode location, for each of these new positions. Main results. Recommendations for montages that maximise stimulation current for the ten brain regions are considered. We noted that the extent to which stimulation is affected by electrode displacement varies depending on both area and montage type. The F3-Fp2 montage was found to be the least stable with up to 38% change in average current density in the left frontal lobe while the Fp1-F4 montage was found to the most stable exhibiting only 1% change when electrodes were displaced. Significance. These results indicate that even relatively small changes in stimulation electrode placement appear to result in surprisingly large

Spectrochemical analysis of plutonium using direct current plasma emission spectrometry

International Nuclear Information System (INIS)

Morris, W.F.; Fadeff, S.K.; Torres, S.

1983-01-01

One year ago, LLNL was just completing the installation of a Direct Current Plasma (DCP) spectrometer for the analysis of Pu and Pu alloys. The installation was completed in December 1982 and has been utilized regularly for Pu analysis since then. This paper discusses the experience with the instrument and some data demonstrating its performance

Use of Direct Current Resistivity Measurements to Assess AISI 304 Austenitic Stainless Steel Sensitization

OpenAIRE

Mesquita, Ramaiany Carneiro; Mecury, José Manoel Rivas; Tanaka, Auro Atsumi; Sousa, Regina Célia de

2015-01-01

This paper describes the feasibility of using direct current electrical resistivity measurements to evaluate AISI 304 austenitic stainless steel sensitization. ASTM A262 – Practice A and double loop electrochemical potentiodynamic reactivation (DL-EPR) tests were performed to assess the degree of sensitization (DoS) qualitatively and quantitatively, and electrical resistivity (ER) was measured by the four-point direct-current potential drop method. The results indicate that the DoS incr...

Virtual Inertia: Current Trends and Future Directions

Directory of Open Access Journals (Sweden)

Ujjwol Tamrakar

2017-06-01

Full Text Available The modern power system is progressing from a synchronous machine-based system towards an inverter-dominated system, with large-scale penetration of renewable energy sources (RESs like wind and photovoltaics. RES units today represent a major share of the generation, and the traditional approach of integrating them as grid following units can lead to frequency instability. Many researchers have pointed towards using inverters with virtual inertia control algorithms so that they appear as synchronous generators to the grid, maintaining and enhancing system stability. This paper presents a literature review of the current state-of-the-art of virtual inertia implementation techniques, and explores potential research directions and challenges. The major virtual inertia topologies are compared and classified. Through literature review and simulations of some selected topologies it has been shown that similar inertial response can be achieved by relating the parameters of these topologies through time constants and inertia constants, although the exact frequency dynamics may vary slightly. The suitability of a topology depends on system control architecture and desired level of detail in replication of the dynamics of synchronous generators. A discussion on the challenges and research directions points out several research needs, especially for systems level integration of virtual inertia systems.

Pharmacologic versus direct-current electrical cardioversion of atrial flutter and fibrillation

NARCIS (Netherlands)

Van Gelder, IC; Tuinenburg, AE; Schoonderwoerd, BS; Tieleman, RG; Crijns, HJGM

1999-01-01

Conversion of atrial flutter and atrial fibrillation (AF) can be achieved by either pharmacologic or direct-current (DC) electrical cardioversion. DC electrical cardioversion is more effective and restores sinus rhythm instantaneously; however, general anesthesia is necessary, which can cause severe

Non-Cyanide Electrodeposited Ag–PTFE Composite Coating Using Direct or Pulsed Current Deposition

Directory of Open Access Journals (Sweden)

Raymond Sieh

2016-07-01

Full Text Available The effects of FC-4 cationic surfactant on electrodeposited Ag–PTFE composite coating using direct or pulsed currents were studied using scanning electron microscope (SEM, energy dispersive X-ray (EDS, optical microscope, and a linear tribometer. FC-4:PTFE in various ratios were added to a non-cyanide succinimide silver complex bath. Direct or pulsed current method was used at a constant current density to enable comparison between both methods. A high incorporation rate of PTFE was successfully achieved, with pulsed current being highly useful in increasing the amount of PTFE in the composite coating. The study of coating wear under sliding showed that a large majority of the electrodeposited coatings still managed to adhere to the substrate, even after 10 wear cycles of sliding tests. Performance improvements were achieved on all the samples with a coefficient of friction (CoF between 0.06 and 0.12.

Performance evaluation of directly photovoltaic powered DC PM (direct current permanent magnet) motor – propeller thrust system

International Nuclear Information System (INIS)

Atlam, Ozcan; Kolhe, Mohan

2013-01-01

Photovoltaic (PV) powered directly coupled electro-mechanical system has wide applications (e.g. PV powered cooling fans in green houses, PV water pumping system, solar vehicles). The objective of this work is to analyse the operation of directly PV powered DC PM (direct current permanent magnet) motor – propeller system for selection of motor parameters. The performance of such system mainly depends on the incident solar radiation, operating cell temperature, DC motor and propeller load parameters. It is observed that the operating points of the PV DC PM motor – propeller system matches very closely with the maximum power points (MPPs) of the PV array, if the DC PM motor – propeller parameters have been properly selected. It is found that for a specific application of such type of system, matching of torque–speed operating points with respect to the maximum power points of PV array are very important. It is ascertained through results that the DC PM motor's armature resistance, magnetic field constant, starting current to overcome the starting torque and torque coefficient are the main parameters. In designing a PV powered DC PM motor for a specific application, selection of these parameters are important for maximum utilization of the PV array output. The results of this system are useful for designing of directly PV powered DC PM motor's for aerodynamic applications. - Highlights: • We analyse the performance of directly PV powered DC PM motor – propeller system. • We examine PV electro-mechanical system for selection of DC motor parameters. • Matching of torque–speed curve to maximum power points of PV array is important

Transcranial direct current stimulation for depression in Alzheimer's disease: study protocol for a randomized controlled trial.

Science.gov (United States)

Narita, Zui; Yokoi, Yuma

2017-06-19

Patients with Alzheimer's disease frequently elicit neuropsychiatric symptoms as well as cognitive deficits. Above all, depression is one of the most common neuropsychiatric symptoms in Alzheimer's disease but antidepressant drugs have not shown significant beneficial effects on it. Moreover, electroconvulsive therapy has not ensured its safety for potential severe adverse events although it does show beneficial clinical effect. Transcranial direct current stimulation can be the safe alternative of neuromodulation, which applies weak direct electrical current to the brain. Although transcranial direct current stimulation has plausible evidence for its effect on depression in young adult patients, no study has explored it in older subjects with depression in Alzheimer's disease. Therefore, we present a study protocol designed to evaluate the safety and clinical effect of transcranial direct current stimulation on depression in Alzheimer's disease in subjects aged over 65 years. This is a two-arm, parallel-design, randomized controlled trial, in which patients and assessors will be blinded. Subjects will be randomized to either an active or a sham transcranial direct current stimulation group. Participants in both groups will be evaluated at baseline, immediately, and 2 weeks after the intervention. This study investigates the safety and effect of transcranial direct current stimulation that may bring a significant impact on both depression and cognition in patients with Alzheimer's disease, and may be useful to enhance their quality of life. ClinicalTrials.gov, NCT02351388 . Registered on 27 January 2015. Last updated on 30 May 2016.

Augmentation of Fear Extinction by Transcranial Direct Current Stimulation (tDCS

Directory of Open Access Journals (Sweden)

Natalie Dittert

2018-04-01

Full Text Available Although posttraumatic stress disorder (PTSD; DSM-V 309.82 and anxiety disorders (DSM-V 300.xx are widely spread mental disorders, the effectiveness of their therapy is still unsatisfying. Non-invasive brain-stimulation techniques like transcranial direct current stimulation (tDCS might be an option to improve extinction learning, which is a main functional factor of exposure-based therapy for anxiety disorders. To examine this hypothesis, we used a fear conditioning paradigm with female faces as conditioned stimuli (CS and a 95-dB female scream as unconditioned stimulus (UCS. We aimed to perform a tDCS of the ventromedial prefrontal cortex (vmPFC, which is mainly involved in the control of extinction-processes. Therefore, we applied two 4 × 4 cm electrodes approximately at the EEG-positions F7 and F8 and used a direct current of 1.5 mA. The 20-min stimulation was started during a 10-min break between acquisition and extinction and went on overall extinction-trials. The healthy participants were randomly assigned in two double-blinded process into two sham stimulation and two verum stimulation groups with opposite current flow directions. To measure the fear reactions, we used skin conductance responses (SCR and subjective ratings. We performed a generalized estimating equations model for the SCR to assess the impact of tDCS and current flow direction on extinction processes for all subjects that showed a successful conditioning (N = 84. The results indicate that tDCS accelerates early extinction processes with a significantly faster loss of CS+/CS– discrimination. The discrimination loss was driven by a significant decrease in reaction toward the CS+ as well as an increase in reaction toward the CS– in the tDCS verum groups, whereas the sham groups showed no significant reaction changes during this period. Therefore, we assume that tDCS of the vmPFC can be used to enhance early extinction processes successfully. But before it should be

Neuroprotective effect of cathodal transcranial direct current stimulation in a rat stroke model.

Science.gov (United States)

Notturno, Francesca; Pace, Marta; Zappasodi, Filippo; Cam, Etrugul; Bassetti, Claudio L; Uncini, Antonino

2014-07-15

Experimental focal brain ischemia generates in the penumbra recurrent depolarizations which spread across the injured cortex inducing infarct growth. Transcranial direct current stimulation can induce a lasting, polarity-specific, modulation of cortical excitability. To verify whether cathodal transcranial direct current stimulation could reduce the infarct size and the number of depolarizations, focal ischemia was induced in the rat by the 3 vessels occlusion technique. In the first experiment 12 ischemic rats received cathodal stimulation (alternating 15 min on and 15 min off) starting 45 min after middle cerebral artery occlusion and lasting 4 h. In the second experiment 12 ischemic rats received cathodal transcranial direct current stimulation with the same protocol but starting soon after middle cerebral artery occlusion and lasting 6 h. In both experiments controls were 12 ischemic rats not receiving stimulation. Cathodal stimulation reduced the infarct volume in the first experiment by 20% (p=0.002) and in the second by 30% (p=0.003). The area of cerebral infarction was smaller in animals receiving cathodal stimulation in both experiments (p=0.005). Cathodal stimulation reduced the number of depolarizations (p=0.023) and infarct volume correlated with the number of depolarizations (p=0.048). Our findings indicate that cathodal transcranial direct current stimulation exert a neuroprotective effect in the acute phase of stroke possibly decreasing the number of spreading depolarizations. These findings may have translational relevance and open a new avenue in neuroprotection of stroke in humans. Copyright © 2014. Published by Elsevier B.V.

Transcranial direct-current stimulation induced in stroke patients with aphasia: a prospective experimental cohort study.

Science.gov (United States)

Santos, Michele Devido; Gagliardi, Rubens José; Mac-Kay, Ana Paula Machado Goyano; Boggio, Paulo Sergio; Lianza, Roberta; Fregni, Felipe

2013-01-01

Previous animal and human studies have shown that transcranial direct current stimulation can induce significant and lasting neuroplasticity and may improve language recovery in patients with aphasia. The objective of the study was to describe a cohort of patients with aphasia after stroke who were treated with transcranial direct current stimulation. Prospective cohort study developed in a public university hospital. Nineteen patients with chronic aphasia received 10 transcranial direct current stimulation sessions lasting 20 minutes each on consecutive days, using a current of 2 mA. The anode was positioned over the supraorbital area and the cathode over the contralateral motor cortex. The following variables were analyzed before and after the 10 neuromodulation sessions: oral language comprehension, copying, dictation, reading, writing, naming and verbal fluency. There were no adverse effects in the study. We found statistically significant differences from before to after stimulation in relation to simple sentence comprehension (P = 0.034), naming (P = 0.041) and verbal fluency for names of animals (P = 0.038). Improved scores for performing these three tasks were seen after stimulation. We observed that excitability of the primary motor cortex through transcranial direct current stimulation was associated with effects on different aspects of language. This can contribute towards future testing in randomized controlled trials.

Modeling of the Direct Current Generator Including the Magnetic Saturation and Temperature Effects

Directory of Open Access Journals (Sweden)

Alfonso J. Mercado-Samur

2013-11-01

Full Text Available In this paper the inclusion of temperature effect on the field resistance on the direct current generator model DC1A, which is valid to stability studies is proposed. First, the linear generator model is presented, after the effect of magnetic saturation and the change in the resistance value due to temperature produced by the field current are included. The comparison of experimental results and model simulations to validate the model is used. A direct current generator model which is a better representation of the generator is obtained. Visual comparison between simulations and experimental results shows the success of the proposed model, because it presents the lowest error of the compared models. The accuracy of the proposed model is observed via Modified Normalized Sum of Squared Errors index equal to 3.8979%.

Current direction-dependent modulation of human hand motor function by intermittent theta burst stimulation (iTBS).

Science.gov (United States)

Shirota, Yuichiro; Dhaka, Suman; Paulus, Walter; Sommer, Martin

2017-05-22

Transcranial magnetic stimulation (TMS) with different current directions can activate different sets of neurons. Current direction can also affect the results of repetitive TMS. To test the influence of uni-directional intermittent theta burst stimulation (iTBS) using different current directions, namely posteroanterior (PA) and anteroposterior (AP), on motor behaviour. In a cross-over design, PA- and AP-iTBS was applied over the left primary motor cortex in 19 healthy, right-handed volunteers. Performance of a finger-tapping task was recorded before and 0, 10, 20, and 30min after the iTBS. The task was conducted with the right and left hands separately at each time point. As a control, AP-iTBS with reduced intensity was applied to 14 participants in a separate session (AP weak condition). The finger-tapping count with the left hand was decreased after PA-iTBS. Neither AP- nor AP weak -iTBS altered the performance. Current direction had a significant impact on the after-effects of iTBS. Copyright © 2017 Elsevier B.V. All rights reserved.

Mild cognitive impairment in Parkinson's disease is improved by transcranial direct current stimulation combined with physical therapy.

Science.gov (United States)

Manenti, Rosa; Brambilla, Michela; Benussi, Alberto; Rosini, Sandra; Cobelli, Chiara; Ferrari, Clarissa; Petesi, Michela; Orizio, Italo; Padovani, Alessandro; Borroni, Barbara; Cotelli, Maria

2016-05-01

Parkinson's disease (PD) is characterized by both motor and cognitive deficits. In PD, physical exercise has been found to improve physical functioning. Recent studies demonstrated that repeated sessions of transcranial direct current stimulation led to an increased performance in cognitive and motor tasks in patients with PD. The present study investigated the effects of anodal transcranial direct current stimulation applied over the dorsolateral prefrontal cortex and combined with physical therapy in PD patients. A total of 20 patients with PD were assigned to 1 of 2 study groups: group 1, anodal transcranial direct current stimulation plus physical therapy (n = 10) or group 2, placebo transcranial direct current stimulation plus physical therapy (n = 10). The 2 weeks of treatment consisted of daily direct current stimulation application for 25 minutes during physical therapy. Long-term effects of treatment were evaluated on clinical, neuropsychological, and motor task performance at 3-month follow-up. An improvement in motor abilities and a reduction of depressive symptoms were observed in both groups after the end of treatment and at 3-month follow-up. The Parkinson's Disease Cognitive Rating Scale and verbal fluency test performances increased only in the anodal direct current stimulation group with a stable effect at follow-up. The application of anodal transcranial direct current stimulation may be a relevant tool to improve cognitive abilities in PD and might be a novel therapeutic strategy for PD patients with mild cognitive impairment. © 2016 International Parkinson and Movement Disorder Society. © 2016 International Parkinson and Movement Disorder Society.

Starting characteristics of direct current motors powered by solar cells

Science.gov (United States)

Singer, S.; Appelbaum, J.

1989-01-01

Direct current motors are used in photovoltaic systems. Important characteristics of electric motors are the starting to rated current and torque ratios. These ratios are dictated by the size of the solar cell array and are different for the various dc motor types. Discussed here is the calculation of the starting to rated current ratio and starting to rated torque ratio of the permanent magnet, and series and shunt excited motors when powered by solar cells for two cases: with and without a maximum-power-point-tracker (MPPT) included in the system. Comparing these two cases, one gets a torque magnification of about 3 for the permanent magnet motor and about 7 for other motor types. The calculation of the torques may assist the PV system designer to determine whether or not to include an MPPT in the system.

Determinants of the electric field during transcranial direct current stimulation

DEFF Research Database (Denmark)

Opitz, Alexander; Paulus, Walter; Will, Susanne

2015-01-01

Transcranial direct current stimulation (tDCS) causes a complex spatial distribution of the electric current flow in the head which hampers the accurate localization of the stimulated brain areas. In this study we show how various anatomical features systematically shape the electric field...... over the motor cortex in small steps to examine the resulting changes of the electric field distribution in the underlying cortex. We examined the effect of skull thickness and composition on the passing currents showing that thinner skull regions lead to higher electric field strengths. This effect...... fluid and the skull, the gyral depth and the distance to the anode and cathode. These factors account for up to 50% of the spatial variation of the electric field strength. Further, we demonstrate that individual anatomical factors can lead to stimulation "hotspots" which are partly resistant...

Design of a Versatile and Low Cost μVolt Level A to D Conversion System for Use in Medical Instrumentation Applications

Directory of Open Access Journals (Sweden)

Neil Robinson

2008-10-01

Full Text Available Modern medical facilities place considerable reliance on electronic instrumentation for purposes of calibration and monitoring of therapeutic processes, many of which employ electrical and electronic apparatus that itself generates considerable levels of interference in the form of background electromagnetic radiation (EMR. Additionally diverse ambient conditions in the clinical environment such as uncontrolled temperature, humidity, noise, and vibration place added stress on sensitive instrumentation. In order to obtain accurate, repeatable, and reliable data in such environments, instrumentation used must be largely immune to these factors. Analogue instrumentation is particularly susceptible to unstable environmental conditions. Sensors typically output an analogue current or voltage and it can be demonstrated that considerable overall benefit to the measuring process would result if sensor outputs could be converted to a robust digital format at the earliest possible stage. A practical and low cost system for A to D conversion at μVolt signal levels is described in this work. It has been successfully employed in portable radiation dosimetry instrumentation and used under diverse clinical conditions and it affords an improvement in signal resolution in excess of an order of magnitude over commonly used analogue techniques.

Light-field-driven currents in graphene

Science.gov (United States)

Higuchi, Takuya; Heide, Christian; Ullmann, Konrad; Weber, Heiko B.; Hommelhoff, Peter

2017-10-01

The ability to steer electrons using the strong electromagnetic field of light has opened up the possibility of controlling electron dynamics on the sub-femtosecond (less than 10-15 seconds) timescale. In dielectrics and semiconductors, various light-field-driven effects have been explored, including high-harmonic generation, sub-optical-cycle interband population transfer and the non-perturbative change of the transient polarizability. In contrast, much less is known about light-field-driven electron dynamics in narrow-bandgap systems or in conductors, in which screening due to free carriers or light absorption hinders the application of strong optical fields. Graphene is a promising platform with which to achieve light-field-driven control of electrons in a conducting material, because of its broadband and ultrafast optical response, weak screening and high damage threshold. Here we show that a current induced in monolayer graphene by two-cycle laser pulses is sensitive to the electric-field waveform, that is, to the exact shape of the optical carrier field of the pulse, which is controlled by the carrier-envelope phase, with a precision on the attosecond (10-18 seconds) timescale. Such a current, dependent on the carrier-envelope phase, shows a striking reversal of the direction of the current as a function of the driving field amplitude at about two volts per nanometre. This reversal indicates a transition of light-matter interaction from the weak-field (photon-driven) regime to the strong-field (light-field-driven) regime, where the intraband dynamics influence interband transitions. We show that in this strong-field regime the electron dynamics are governed by sub-optical-cycle Landau-Zener-Stückelberg interference, composed of coherent repeated Landau-Zener transitions on the femtosecond timescale. Furthermore, the influence of this sub-optical-cycle interference can be controlled with the laser polarization state. These coherent electron dynamics in

Self-consistent model for pulsed direct-current N2 glow discharge

International Nuclear Information System (INIS)

Liu Chengsen

2005-01-01

A self-consistent analysis of a pulsed direct-current (DC) N 2 glow discharge is presented. The model is based on a numerical solution of the continuity equations for electron and ions coupled with Poisson's equation. The spatial-temporal variations of ionic and electronic densities and electric field are obtained. The electric field structure exhibits all the characteristic regions of a typical glow discharge (the cathode fall, the negative glow, and the positive column). Current-voltage characteristics of the discharge can be obtained from the model. The calculated current-voltage results using a constant secondary electron emission coefficient for the gas pressure 133.32 Pa are in reasonable agreement with experiment. (authors)

Direct current hopping conductance along DNA chain

Institute of Scientific and Technical Information of China (English)

Ma Song-Shan; Xu Hui; Liu Xiao-Liang; Li Ming-Jun

2007-01-01

This paper proposes a model of direct current(DC) electron hopping transport in DNA,in which DNA is considered as a binary one-dimensional disordered system.To quantitatively study the DC conductivity in DNA,it numerically calculates the DC conductivity of DNA chains with difierent parameter values.The result shows that the DC conductivity of DNA chain increases with the increase of temperature.And the conductivity of DNA chain is depended on the probability P.which represents the degree of compositional disorder in a DNA sequence to some extent.For P＜0.5,the conductivity of DNA chain decreases with the increase of P,while for P≥0.5,the conductivity increases with the increase of p.The DC conductivity in DNA chain also varies with the change of the electric field,it presents non-Ohm's law conductivity characteristics.

Transcranial direct-current stimulation induced in stroke patients with aphasia: a prospective experimental cohort study

Directory of Open Access Journals (Sweden)

Michele Devido Santos

Full Text Available CONTEXT AND OBJECTIVE: Previous animal and human studies have shown that transcranial direct current stimulation can induce significant and lasting neuroplasticity and may improve language recovery in patients with aphasia. The objective of the study was to describe a cohort of patients with aphasia after stroke who were treated with transcranial direct current stimulation. DESIGN AND SETTING: Prospective cohort study developed in a public university hospital. METHODS: Nineteen patients with chronic aphasia received 10 transcranial direct current stimulation sessions lasting 20 minutes each on consecutive days, using a current of 2 mA. The anode was positioned over the supraorbital area and the cathode over the contralateral motor cortex. The following variables were analyzed before and after the 10 neuromodulation sessions: oral language comprehension, copying, dictation, reading, writing, naming and verbal fluency. RESULTS: There were no adverse effects in the study. We found statistically significant differences from before to after stimulation in relation to simple sentence comprehension (P = 0.034, naming (P = 0.041 and verbal fluency for names of animals (P = 0.038. Improved scores for performing these three tasks were seen after stimulation. CONCLUSIONS: We observed that excitability of the primary motor cortex through transcranial direct current stimulation was associated with effects on different aspects of language. This can contribute towards future testing in randomized controlled trials.

Fabrication And Determination Of Coefficient Absorption Of Hydrogenated Amorphous Silicon By Direct Evaporation Method

International Nuclear Information System (INIS)

Santoso, Agus; Darsono; Sujitno, Tjipto; Suprapto

1996-01-01

Fabrication and characterization of hydrogenated amorphous silicon produced by direct evaporation method have been done. The experiment was carried out at pressure conditions of 2 x 10-5 torr, RF frequency of 13.56 MHz, hydrogen gas flow of 0,8 1/minute, electrode distance of 2.48 cm. voltage electrode of 700 volt and evaporation time 1.45 minute. Using UV-VIS spectrophotometer, it is found that at wavelength of 359 nm, the absorbance degree of material that was by direct hydrogenated method was 0,886. This means that more hydrogen are absorbed by direct method While, if the hydrogenation is carried out by means of indirect method, the degree of absorbance at the wavelength of 359 nm is 0,103. From this result, it can be concluded that the direct methods is better than indirect method

Transcranial direct-current stimulation induced in stroke patients with aphasia: a prospective experimental cohort study

OpenAIRE

Santos,Michele Devido; Gagliardi,Rubens José; Mac-Kay,Ana Paula Machado Goyano; Boggio,Paulo Sergio; Lianza,Roberta; Fregni,Felipe

2013-01-01

CONTEXT AND OBJECTIVE: Previous animal and human studies have shown that transcranial direct current stimulation can induce significant and lasting neuroplasticity and may improve language recovery in patients with aphasia. The objective of the study was to describe a cohort of patients with aphasia after stroke who were treated with transcranial direct current stimulation. DESIGN AND SETTING: Prospective cohort study developed in a public university hospital. METHODS: Nineteen patients with ...

An Annotated Bibliography of High-Voltage Direct-Current Transmission and Flexible AC Transmission (FACTS) Devices, 1991-1993.

Energy Technology Data Exchange (ETDEWEB)

Litzenberger, Wayne; Lava, Val

1994-08-01

References are contained for HVDC systems, converter stations and components, overhead transmission lines, cable transmission, system design and operations, simulation of high voltage direct current systems, high-voltage direct current installations, and flexible AC transmission system (FACTS).

Combining physical training with transcranial direct current stimulation to improve gait in Parkinson's disease: a pilot randomized controlled study.

Science.gov (United States)

Kaski, D; Dominguez, R O; Allum, J H; Islam, A F; Bronstein, A M

2014-11-01

To improve gait and balance in patients with Parkinson's disease by combining anodal transcranial direct current stimulation with physical training. In a double-blind design, one group (physical training; n = 8) underwent gait and balance training during transcranial direct current stimulation (tDCS; real/sham). Real stimulation consisted of 15 minutes of 2 mA transcranial direct current stimulation over primary motor and premotor cortex. For sham, the current was switched off after 30 seconds. Patients received the opposite stimulation (sham/real) with physical training one week later; the second group (No physical training; n = 8) received stimulation (real/sham) but no training, and also repeated a sequential transcranial direct current stimulation session one week later (sham/real). Hospital Srio Libanes, Buenos Aires, Argentina. Sixteen community-dwelling patients with Parkinson's disease. Transcranial direct current stimulation with and without concomitant physical training. Gait velocity (primary gait outcome), stride length, timed 6-minute walk test, Timed Up and Go Test (secondary outcomes), and performance on the pull test (primary balance outcome). Transcranial direct current stimulation with physical training increased gait velocity (mean = 29.5%, SD = 13; p transcranial direct current stimulation alone. There was no isolated benefit of transcranial direct current stimulation alone. Although physical training improved gait velocity (mean = 15.5%, SD = 12.3; p = 0.03), these effects were comparatively less than with combined tDCS + physical therapy (p stimulation-related improvements were seen in patients with more advanced disease. Anodal transcranial direct current stimulation during physical training improves gait and balance in patients with Parkinson's disease. Power calculations revealed that 14 patients per treatment arm (α = 0.05; power = 0.8) are required for a definitive trial. © The Author(s) 2014.

The Philippine historical earthquakecatalog: its development, current stateand future directions

OpenAIRE

Bautista, M. L. P.; Bautista, B. C.

2004-01-01

This report will trace the development of the historical earthquake catalog of the Philippines, assess its present state and recommend future research directions. The current Philippine historical earthquake catalog is culled from various catalogs, both global and local, that were developed since the first Philippine catalog by Perrey was published in 1860. While early global catalogs gave simple mention of earthquakes in the Philippines, more focused earthquake catalogs about the Philippines...

Determination of optimal electrode positions for transcranial direct current stimulation (tDCS)

International Nuclear Information System (INIS)

Im, Chang-Hwan; Jung, Hui-Hun; Choi, Jung-Do; Lee, Soo Yeol; Jung, Ki-Young

2008-01-01

The present study introduces a new approach to determining optimal electrode positions in transcranial direct current stimulation (tDCS). Electric field and 3D conduction current density were analyzed using 3D finite element method (FEM) formulated for a dc conduction problem. The electrode positions for minimal current injection were optimized by changing the Cartesian coordinate system into the spherical coordinate system and applying the (2+6) evolution strategy (ES) algorithm. Preliminary simulation studies applied to a standard three-layer head model demonstrated that the proposed approach is promising in enhancing the performance of tDCS. (note)

Determination of optimal electrode positions for transcranial direct current stimulation (tDCS)

Energy Technology Data Exchange (ETDEWEB)

Im, Chang-Hwan; Jung, Hui-Hun; Choi, Jung-Do [Department of Biomedical Engineering, Yonsei University, Wonju, 220-710 (Korea, Republic of); Lee, Soo Yeol [Department of Biomedical Engineering, Kyung Hee University, Suwon (Korea, Republic of); Jung, Ki-Young [Korea University Medical Center, Korea University College of Medicine, Seoul (Korea, Republic of)], E-mail: ich@yonsei.ac.kr

2008-06-07

The present study introduces a new approach to determining optimal electrode positions in transcranial direct current stimulation (tDCS). Electric field and 3D conduction current density were analyzed using 3D finite element method (FEM) formulated for a dc conduction problem. The electrode positions for minimal current injection were optimized by changing the Cartesian coordinate system into the spherical coordinate system and applying the (2+6) evolution strategy (ES) algorithm. Preliminary simulation studies applied to a standard three-layer head model demonstrated that the proposed approach is promising in enhancing the performance of tDCS. (note)

Large rectification magnetoresistance in nonmagnetic Al/Ge/Al heterojunctions

OpenAIRE

Zhang, Kun; Li, Huan-huan; Grünberg, Peter; Li, Qiang; Ye, Sheng-tao; Tian, Yu-feng; Yan, Shi-shen; Lin, Zhao-jun; Kang, Shi-shou; Chen, Yan-xue; Liu, Guo-lei; Mei, and Liang-mo

2015-01-01

Magnetoresistance and rectification are two fundamental physical properties of heterojunctions and respectively have wide applications in spintronics devices. Being different from the well known various magnetoresistance effects, here we report a brand new large magnetoresistance that can be regarded as rectification magnetoresistance: the application of a pure small sinusoidal alternating-current to the nonmagnetic Al/Ge Schottky heterojunctions can generate a significant direct-current volt...

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-06-15

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

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

International Nuclear Information System (INIS)

Lim, Sung Hun; Han, Tae Hee

2017-01-01

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

Combined Dextroamphetamine and Transcranial Direct Current Stimulation in Poststroke Aphasia.

Science.gov (United States)

Keser, Zafer; Dehgan, Michelle Weber; Shadravan, Shaparak; Yozbatiran, Nuray; Maher, Lynn M; Francisco, Gerard E

2017-10-01

There is a growing need for various effective adjunctive treatment options for speech recovery after stroke. A pharmacological agent combined with noninvasive brain stimulation has not been previously reported for poststroke aphasia recovery. In this "proof of concept" study, we aimed to test the safety of a combined intervention consisting of dextroamphetamine, transcranial direct current stimulation, and speech and language therapy in subjects with nonfluent aphasia. Ten subjects with chronic nonfluent aphasia underwent two experiments where they received dextroamphetamine or placebo along with transcranial direct current stimulation and speech and language therapy on two separate days. The Western Aphasia Battery-Revised was used to monitor changes in speech performance. No serious adverse events were observed. There was no significant increase in blood pressure with amphetamine or deterioration in speech and language performance. Western Aphasia Battery-Revised aphasia quotient and language quotient showed a statistically significant increase in the active experiment. Comparison of proportional changes of aphasia quotient and language quotient in active experiment with those in placebo experiment showed significant difference. We showed that the triple combination therapy is safe and implementable and seems to induce positive changes in speech and language performance in the patients with chronic nonfluent aphasia due to stroke.

Eddy current imaging. Simplifying the direct problem. Analysis of a 2D case with formulations

International Nuclear Information System (INIS)

Spineanu, A.; Zorgati, R.

1995-01-01

Eddy current non-destructive testing is used by EDF to detect faults affecting conductive objects such as steam generator tubes. A new technique, known as eddy current imaging, is being developed to facilitate diagnosis in this context. The first stage in this work, discussed in the present paper, consists in solving the direct problem. This entails determining the measurable quantities, on the basis of a thorough knowledge of the material considered. This was done by formulating the direct problem in terms of eddy currents in general 3D geometry context, applying distribution theory and Maxwell equations. Since no direct problem code was available we resorted to simplified situations. Taking care not to interfere with previous developments or those to be attempted in an inversion context, we studied the case of a flaw affecting a 2D structure, illuminated by a plane wave type probe. For this configuration, we studied the exact model and compared results with those of a linearized simplified model. This study emphasizes the ill-posed situation of the eddy current inverse problem related with the severe electromagnetic field attenuation. This means that regularization of the inverse problem, although absolutely necessary, will not be sufficient. Owing to the simplicity of the models available and implemented during the inversion process, processing real data would not yet be possible. We must first focus all our efforts on the direct 3 D problem, in conformity with the requirements of the inverse procedure ad describing a realistic eddy current NDT situation. At the same time, consideration should be given to the design of a specific probe customized for eddy current imaging. (authors). 9 refs., 5 figs., 3 appends

Differential modulation of corticospinal excitability by different current densities of anodal transcranial direct current stimulation.

Directory of Open Access Journals (Sweden)

Andisheh Bastani

Full Text Available BACKGROUND: Novel non-invasive brain stimulation techniques such as transcranial direct current stimulation (tDCS have been developed in recent years. TDCS-induced corticospinal excitability changes depend on two important factors current intensity and stimulation duration. Despite clinical success with existing tDCS parameters, optimal protocols are still not entirely set. OBJECTIVE/HYPOTHESIS: The current study aimed to investigate the effects of four different anodal tDCS (a-tDCS current densities on corticospinal excitability. METHODS: Four current intensities of 0.3, 0.7, 1.4 and 2 mA resulting in current densities (CDs of 0.013, 0.029, 0.058 and 0.083 mA/cm(2 were applied on twelve right-handed (mean age 34.5±10.32 yrs healthy individuals in different sessions at least 48 hours apart. a-tDCS was applied continuously for 10 minute, with constant active and reference electrode sizes of 24 and 35 cm(2 respectively. The corticospinal excitability of the extensor carpi radialis muscle (ECR was measured before and immediately after the intervention and at 10, 20 and 30 minutes thereafter. RESULTS: Post hoc comparisons showed significant differences in corticospinal excitability changes for CDs of 0.013 mA/cm(2 and 0.029 mA/cm(2 (P = 0.003. There were no significant differences between excitability changes for the 0.013 mA/cm(2 and 0.058 mA/cm(2 (P = 0.080 or 0.013 mA/cm(2 and 0.083 mA/cm(2 (P = 0.484 conditions. CONCLUSION: This study found that a-tDCS with a current density of 0.013 mA/cm(2 induces significantly larger corticospinal excitability changes than CDs of 0.029 mA/cm(2. The implication is that might help to avoid applying unwanted amount of current to the cortical areas.

Transcranial Direct Current Stimulation in Children and Adolescents With Attention-Deficit/Hyperactivity Disorder (ADHD): A Pilot Study.

Science.gov (United States)

Bandeira, Igor Dórea; Guimarães, Rachel Silvany Quadros; Jagersbacher, João Gabriel; Barretto, Thiago Lima; de Jesus-Silva, Jéssica Regina; Santos, Samantha Nunes; Argollo, Nayara; Lucena, Rita

2016-06-01

Studies investigating the possible benefits of transcranial direct current stimulation on left dorsolateral prefrontal cortex in children and adolescents with attention-deficit hyperactivity disorder (ADHD) have not been performed. This study assesses the effect of transcranial direct current stimulation in children and adolescents with ADHD on neuropsychological tests of visual attention, visual and verbal working memory, and inhibitory control. An auto-matched clinical trial was performed involving transcranial direct current stimulation in children and adolescents with ADHD, using SNAP-IV and subtests Vocabulary and Cubes of the Wechsler Intelligence Scale for Children III (WISC-III). Subjects were assessed before and after transcranial direct current stimulation sessions with the Digit Span subtest of the WISC-III, inhibitory control subtest of the NEPSY-II, Corsi cubes, and the Visual Attention Test (TAVIS-3). There were 9 individuals with ADHD according to Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) criteria. There was statistically significant difference in some aspects of TAVIS-3 tests and the inhibitory control subtest of NEPSY-II. Transcranial direct current stimulation can be related to a more efficient processing speed, improved detection of stimuli, and improved ability to switch between an ongoing activity and a new one. © The Author(s) 2016.

Subcortical structures in humans can be facilitated by transcranial direct current stimulation

NARCIS (Netherlands)

Nonnekes, J.H.; Arrogi, A.; Munneke, M.A.M.; Asseldonk, E.H. van; Nijhuis, L.B.; Geurts, A.C.H.; Weerdesteyn, V.G.M.

2014-01-01

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that alters cortical excitability. Interestingly, in recent animal studies facilitatory effects of tDCS have also been observed on subcortical structures. Here, we sought to provide evidence for the potential

Subcortical Structures in Humans Can Be Facilitated by Transcranial Direct Current Stimulation

NARCIS (Netherlands)

Nonnekes, Johan Hendrik; Arrogi, A.; Munneke, M.A.M.; van Asseldonk, Edwin H.F.; Oude Nijhuis, L.B.; Geurts, A.C.; Weerdesteyn, V.

2014-01-01

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that alters cortical excitability. Interestingly, in recent animal studies facilitatory effects of tDCS have also been observed on subcortical structures. Here, we sought to provide evidence for the potential

Simulating Transcranial Direct Current Stimulation With a Detailed Anisotropic Human Head Model

NARCIS (Netherlands)

Rampersad, S.; Janssen, A.J.E.M.; Lucka, F.; Aydin, U.; Lanfer, B.; Lew, S.; Wolters, C.H.; Stegeman, D.F.; Oostendorp, T.F.

2014-01-01

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique able to induce long-lasting changes in cortical excitability that can benefit cognitive functioning and clinical treatment. In order to both better understand the mechanisms behind tDCS and possibly improve

Simulating transcranial direct current stimulation with a detailed anisotropic human head model

NARCIS (Netherlands)

Rampersad, S.M.; Janssen, A.M.; Lucka, F.; Aydin, U.; Lanfer, B.; Lew, S.; Wolters, C.H.; Stegeman, D.F.; Oostendorp, T.F.

2014-01-01

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique able to induce long-lasting changes in cortical excitability that can benefit cognitive functioning and clinical treatment. In order to both better understand the mechanisms behind tDCS and possibly improve

Summary and viewgraphs from the Q-121 US/Japan advanced current drive concepts workshop

International Nuclear Information System (INIS)

Bonoli, P.; Porkolab, M.; Chan, V.; Pinsker, R.; Politzer, P.; Darrow, D.; Fukuyama, Atsushi; Imai, Tsuyoshi; Watari, Tetsuo; Itoh, Satoshi; Nakamura, Yukio; James, R.; Logan, G.; Porter, G.; Thomassen, K.; Lyon, J.; Mau, Tak; Tanaka, Hitoshi; Tanaka, Shigetoshi

1990-01-01

With the emphasis placed on current drive by ITER, which requires steady state operation in its engineering phase, it is important to bring theory and experiment in agreement for each of the schemes that could be used in that design. Both neutral beam and lower hybrid (LH) schemes are in excellent shape in that regard. Since the projected efficiency of all schemes is marginal it is also important to continue our search for more efficient processes. This workshop featured experimental and theoretical work in each processes. This workshop featured experimental and theoretical work in each of these areas, that is, validation of theory and the search for better ideas. There were a number of notable results to report, the most striking again (as with last year) the long pulse operation of TRIAM-1M. A low current was sustained for over 1 hour with LH waves, using new hall-effect sensors in the equilibrium field circuit to maintain position control. In JT-60, by sharpening the wave spectrum the current drive efficiency was improved to 0.34 x 10 20 m -2 A/W and 1.5 MA of current was driven entirely by the lower hybrid system. Also in that machine, using two different LH frequencies, the H-mode was entered. Finally, by using the LH system for startup they saved 2.5 resistive volt-sec of flux, which if extrapolated to ITER would save 40 volt-sec there. For the first time, and experiment on ECH current drive showed reasonable agreement with theory. Those experiments are reported here by James (LLNL) on the D3-D machine. Substantially lower ECH current drive than expected theoretically was observed on WT-3, but if differed by being in a low absorption regime. Nonetheless, excellent physics results were achieved in the WT-3 experiments, notably in having careful measurements of the parallel velocity distributions

ac electrokinetic micropumps: The effect of geometrical confinement, Faradaic current injection, and nonlinear surface capacitance

DEFF Research Database (Denmark)

Olesen, Laurits Højgaard; Bruus, Henrik; Ajdari, A.

2006-01-01

therefore extend the latter theories to account for three experimentally relevant effects: (i) vertical confinement of the pumping channel, (ii) Faradaic currents from electrochemical reactions at the electrodes, and (iii) nonlinear surface capacitance of the Debye layer. We report here that these effects......Recent experiments have demonstrated that ac electrokinetic micropumps permit integrable, local, and fast pumping (velocities similar to mm/s) with low driving voltage of a few volts only. However, they also displayed many quantitative and qualitative discrepancies with existing theories. We...

Method and system for a gas tube-based current source high voltage direct current transmission system

Science.gov (United States)

She, Xu; Chokhawala, Rahul Shantilal; Bray, James William; Sommerer, Timothy John; Zhou, Rui; Zhang, Di

2017-08-29

A high-voltage direct-current (HVDC) transmission system includes an alternating current (AC) electrical source and a power converter channel that includes an AC-DC converter electrically coupled to the electrical source and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and the DC-AC inverter each include a plurality of legs that includes at least one switching device. The power converter channel further includes a commutating circuit communicatively coupled to one or more switching devices. The commutating circuit is configured to "switch on" one of the switching devices during a first portion of a cycle of the H-bridge switching circuits and "switch off" the switching device during a second portion of the cycle of the first and second H-bridge switching circuits.

An image-guided transcranial direct current stimulation system: a pilot phantom study

International Nuclear Information System (INIS)

Jung, Young-Jin; Kim, Jung-Hoon; Kim, Daejeong; Im, Chang-Hwan

2013-01-01

In this study, an image-guided transcranial direct current stimulation (IG-tDCS) system that can deliver an increased stimulation current to a target brain area without the need to adjust the location of an active electrode was implemented. This IG-tDCS system was based on the array-type tDCS concept, which was validated through computer simulations in a previous study. Unlike a previous study, the present IG-tDCS system adopts a single reference electrode and an active electrode array consisting of 16 (4 × 4) sub-electrodes. The proposed IG-tDCS system is capable of shaping current flow inside the human head by controlling the input currents of the arrayed electrodes. Once a target brain area has been selected, the optimal injection current of each arrayed sub-electrode is evaluated automatically using a genetic algorithm in order to deliver the maximum available current to the target area. The operation of our pilot system was confirmed through a simple phantom experiment. (paper)

Multi-terminal direct-current grids modeling, analysis, and control

CERN Document Server

Chaudhuri, Nilanjan; Majumder, Rajat; Yazdani, Amirnaser

2014-01-01

A comprehensive modeling, analysis, and control design framework for multi-terminal direct current (MTDC) grids is presented together with their interaction with the surrounding AC networks and the impact on overall stability. The first book of its kind on the topic of multi-terminal DC (MTDC) grids  Presents a comprehensive modeling framework for MTDC grids which is compatible with the standard AC system modeling for stability studies Includes modal analysis and study of the interactions between the MTDC grid and the surrounding AC systems Addresses the problems of autonomous power sharing an

Single-layer skull approximations perform well in transcranial direct current stimulation modeling

NARCIS (Netherlands)

Rampersad, S.M.; Stegeman, D.F.; Oostendorp, T.F.

2013-01-01

In modeling the effect of transcranial direct current stimulation, the representation of the skull is an important factor. In a spherical model, we compared a realistic skull modeling approach, in which the skull consisted of three isotropic layers, to anisotropic and isotropic single-layer

Individualized model predicts brain current flow during transcranial direct-current stimulation treatment in responsive stroke patient.

Science.gov (United States)

Datta, Abhishek; Baker, Julie M; Bikson, Marom; Fridriksson, Julius

2011-07-01

Although numerous published reports have demonstrated the beneficial effects of transcranial direct-current stimulation (tDCS) on task performance, fundamental questions remain regarding the optimal electrode configuration on the scalp. Moreover, it is expected that lesioned brain tissue will influence current flow and should therefore be considered (and perhaps leveraged) in the design of individualized tDCS therapies for stroke. The current report demonstrates how different electrode configurations influence the flow of electrical current through brain tissue in a patient who responded positively to a tDCS treatment targeting aphasia. The patient, a 60-year-old man, sustained a left hemisphere ischemic stroke (lesion size = 87.42 mL) 64 months before his participation. In this study, we present results from the first high-resolution (1 mm(3)) model of tDCS in a brain with considerable stroke-related damage; the model was individualized for the patient who received anodal tDCS to his left frontal cortex with the reference cathode electrode placed on his right shoulder. We modeled the resulting brain current flow and also considered three additional reference electrode positions: right mastoid, right orbitofrontal cortex, and a "mirror" configuration with the anode over the undamaged right cortex. Our results demonstrate the profound effect of lesioned tissue on resulting current flow and the ability to modulate current pattern through the brain, including perilesional regions, through electrode montage design. The complexity of brain current flow modulation by detailed normal and pathologic anatomy suggest: (1) That computational models are critical for the rational interpretation and design of individualized tDCS stroke-therapy; and (2) These models must accurately reproduce head anatomy as shown here. Copyright © 2011 Elsevier Inc. All rights reserved.

Consumer Mobile Health Apps: Current State, Barriers, and Future Directions.

Science.gov (United States)

Kao, Cheng-Kai; Liebovitz, David M

2017-05-01

This paper discusses the current state, barriers, and future directions of consumer-facing applications (apps). There are currently more than 165,000 mobile health apps publicly available in major app stores, the vast majority of which are designed for patients. The top 2 categories are wellness management and disease management apps, whereas other categories include self-diagnosis, medication reminder, and electronic patient portal apps. Apps specific to physical medicine and rehabilitation also are reviewed. These apps have the potential to provide low-cost, around-the-clock access to high-quality, evidence-based health information to end users on a global scale. However, they have not yet lived up to their potential due to multiple barriers, including lack of regulatory oversight, limited evidence-based literature, and concerns of privacy and security. The future directions may consist of improving data integration into the health care system, an interoperable app platform allowing access to electronic health record data, cloud-based personal health record across health care networks, and increasing app prescription by health care providers. For consumer mobile health apps to fully contribute value to health care delivery and chronic disease management, all stakeholders within the ecosystem must collaborate to overcome the significant barriers. Copyright © 2017 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Transcranial direct current stimulation over left inferior frontal cortex improves speech fluency in adults who stutter.

Science.gov (United States)

Chesters, Jennifer; Möttönen, Riikka; Watkins, Kate E

2018-04-01

See Crinion (doi:10.1093/brain/awy075) for a scientific commentary on this article.Stuttering is a neurodevelopmental condition affecting 5% of children, and persisting in 1% of adults. Promoting lasting fluency improvement in adults who stutter is a particular challenge. Novel interventions to improve outcomes are of value, therefore. Previous work in patients with acquired motor and language disorders reported enhanced benefits of behavioural therapies when paired with transcranial direct current stimulation. Here, we report the results of the first trial investigating whether transcranial direct current stimulation can improve speech fluency in adults who stutter. We predicted that applying anodal stimulation to the left inferior frontal cortex during speech production with temporary fluency inducers would result in longer-lasting fluency improvements. Thirty male adults who stutter completed a randomized, double-blind, controlled trial of anodal transcranial direct current stimulation over left inferior frontal cortex. Fifteen participants received 20 min of 1-mA stimulation on five consecutive days while speech fluency was temporarily induced using choral and metronome-timed speech. The other 15 participants received the same speech fluency intervention with sham stimulation. Speech fluency during reading and conversation was assessed at baseline, before and after the stimulation on each day of the 5-day intervention, and at 1 and 6 weeks after the end of the intervention. Anodal stimulation combined with speech fluency training significantly reduced the percentage of disfluent speech measured 1 week after the intervention compared with fluency intervention alone. At 6 weeks after the intervention, this improvement was maintained during reading but not during conversation. Outcome scores at both post-intervention time points on a clinical assessment tool (the Stuttering Severity Instrument, version 4) also showed significant improvement in the group receiving

Development of an intelligent high-voltage direct-current power supply for nuclear detectors

International Nuclear Information System (INIS)

Zhao Xiuliang

1997-01-01

The operation and performances of a new type direct-current high-voltage power supply are described. The power supply with intelligent feature is controlled by a single-chip microcomputer (8031), and various kinds of output voltage can be preset. The output-voltage is monitored and regulated by the single-chip microcomputer and displayed by LED. The output voltage is stable when the load current is within the allowable limits

Current ethical and legal issues in health-related direct-to-consumer genetic testing.

Science.gov (United States)

Niemiec, Emilia; Kalokairinou, Louiza; Howard, Heidi Carmen

2017-09-01

A variety of health-related genetic testing is currently advertized directly to consumers. This article provides a timely overview of direct-to-consumer genetic testing (DTC GT) and salient ethical issues, as well as an analysis of the impact of the recently adopted regulation on in vitro diagnostic medical devices on DTC GT. DTC GT companies currently employ new testing approaches, report on a wide spectrum of conditions and target new groups of consumers. Such activities raise ethical issues including the questionable analytic and clinical validity of tests, the adequacy of informed consent, potentially misleading advertizing, testing in children, research uses and commercialization of genomic data. The recently adopted regulation on in vitro diagnostic medical devices may limit the offers of predisposition DTC GT in the EU market.

The effect of current flow direction on motor hot spot allocation by transcranial magnetic stimulation.

Science.gov (United States)

Stephani, Caspar; Paulus, Walter; Sommer, Martin

2016-01-01

The objective of this study was to investigate the significance of pulse configurations and current direction for corticospinal activation using transcranial magnetic stimulation (TMS). In 11 healthy subjects (8 female), a motor map for the motor evoked potentials (MEPs) recorded from the first dorsal interosseus (FDI), abductor digiti minimi (ADM), extensor carpi radialis, and biceps brachii (BB) muscles of the dominant side was established. Starting from a manually determined hot spot of the FDI representation, we measured MEPs at equal oriented points on an hexagonal grid, with 7 MEPs recorded at each point, using the following pulse configurations: posteriorly directed monophasic (Mo-P), anteriorly directed monophasic (Mo-A), biphasic with the more relevant second cycle oriented posteriorly (Bi-P) as well as a reversed biphasic condition (Bi-A). For each pulse configuration, a hot spot was determined and a center of gravity (CoG) was calculated. We found that the factor current direction had an effect on location of the CoG-adjusted hot spot in the cranio-caudal axis but not in the latero-medial direction with anteriorly directed pulses locating the CoG more anteriorly and vice versa. In addition, the CoG for the FDI was more laterally than the cortical representations for the abductor digiti minimi (ADM) and extensor carpi radialis (ECR) which were registered as well. The results indicate that direction of the current pulse should be taken into account for determination of the motor representation of a muscle by TMS. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

Effect-directed analysis: Current status and future challenges

Science.gov (United States)

Hong, Seongjin; Giesy, John P.; Lee, Jung-Suk; Lee, Jong-Hyeon; Khim, Jong Seong

2016-09-01

Effect-directed analysis (EDA) has become useful for identification of toxicant(s) that occur in mixtures in the environment, especially those that are causative agents of specific adverse effects. Here, we summarize and review EDA methodology including preparation of samples, biological analyses, fractionations, and instrumental analyses, highlighting key scientific advancements. A total of 63 documents since 1999 (Scopus search) including 46 research articles, 13 review papers, and 4 project descriptions, have been collected and reviewed in this study. At the early stage (1999-2010), most studies that applied EDA focused on organic extracts of freshwater and coastal contaminated sediments and wastewater. Toxic effects were often measured using cell-based bioassays ( in vitro) and the causative chemicals were identified by use of low resolution gas chromatography with mass selective detector (GCMSD). More recently (2010-present), EDA has been extended to various matrices such as biota, soil, crude oil, and suspended solids and techniques have been improved to include determination of bioavailability in vivo. In particular, methods for non-target screenings of organic chemicals in environmental samples using cutting-edge instrumentation such as time of flight-mass spectrometry (ToF-MS), Fourier transform-ion cyclotron resonance (FT-ICR), and Orbitrap mass spectrometer have been developed. This overview provides descriptions of recent improvements of EDA and suggests future research directions based on current understandings and limitations.

Transcranial Direct Current Stimulation: Considerations for Research in Adolescent Depression

Directory of Open Access Journals (Sweden)

Jonathan C. Lee

2017-06-01

Full Text Available Adolescent depression is a prevalent disorder with substantial morbidity and mortality. Current treatment interventions do not target relevant pathophysiology and are frequently ineffective, thereby leading to a substantial burden for individuals, families, and society. During adolescence, the prefrontal cortex undergoes extensive structural and functional changes. Recent work suggests that frontolimbic development in depressed adolescents is delayed or aberrant. The judicious application of non-invasive brain stimulation techniques to the prefrontal cortex may present a promising opportunity for durable interventions in adolescent depression. Transcranial direct current stimulation (tDCS applies a low-intensity, continuous current that alters cortical excitability. While this modality does not elicit action potentials, it is thought to manipulate neuronal activity and neuroplasticity. Specifically, tDCS may modulate N-methyl-d-aspartate receptors and L-type voltage-gated calcium channels and effect changes through long-term potentiation or long-term depression-like mechanisms. This mini-review considers the neurobiological rationale for developing tDCS protocols in adolescent depression, reviews existing work in adult mood disorders, surveys the existing tDCS literature in adolescent populations, reviews safety studies, and discusses distinct ethical considerations in work with adolescents.

Effectiveness of direct-current cardioversion for treatment of supraventricular tachyarrhythmias, in particular atrial fibrillation, in surgical intensive care patients.

Science.gov (United States)

Mayr, Andreas; Ritsch, Nicole; Knotzer, Hans; Dünser, Martin; Schobersberger, Wolfgang; Ulmer, Hanno; Mutz, Norbert; Hasibeder, Walter

2003-02-01

To evaluate primary success rate and effectiveness of direct-current cardioversion in postoperative critically ill patients with new-onset supraventricular tachyarrhythmias. Prospective intervention study. Twelve-bed surgical intensive care unit in a university teaching hospital. Thirty-seven consecutive, adult surgical intensive care unit patients with new-onset supraventricular tachyarrhythmias without previous history of tachyarrhythmias. Direct-current cardioversion using a monophasic, damped sinus-wave defibrillator. Energy levels used were 50, 100, 200, and 300 J for regular supraventricular tachyarrhythmias (n = 6) and 100, 200, and 360 J for irregular supraventricular tachyarrhythmias (n = 31). None of the patients was hypoxic, hypokalemic, or hypomagnesemic at onset of supraventricular tachyarrhythmia. Direct-current cardioversion restored sinus rhythm in 13 of 37 patients (35% primary responders). Most patients responded to the first or second direct-current cardioversion shock. Only one of 25 patients requiring more than two direct-current cardioversion shocks converted into sinus rhythm. Primary responders were significantly younger and demonstrated significant differences in arterial Po2 values at onset of supraventricular tachyarrhythmias compared with nonresponders. At 24 and 48 hrs, only six (16%) and five (13.5%) patients remained in sinus rhythm, respectively. In contrast to recent literature, direct-current cardioversion proved to be an ineffective method for treatment of new-onset supraventricular tachyarrhythmias and, in particular, atrial fibrillation with a rapid ventricular response in surgical intensive care unit patients.

Design of all-optical, hot-electron current-direction-switching device based on geometrical asymmetry.

Science.gov (United States)

Kumarasinghe, Chathurangi S; Premaratne, Malin; Gunapala, Sarath D; Agrawal, Govind P

2016-02-18

We propose a nano-scale current-direction-switching device(CDSD) that operates based on the novel phenomenon of geometrical asymmetry between two hot-electron generating plasmonic nanostructures. The proposed device is easy to fabricate and economical to develop compared to most other existing designs. It also has the ability to function without external wiring in nano or molecular circuitry since it is powered and controlled optically. We consider a such CDSD made of two dissimilar nanorods separated by a thin but finite potential barrier and theoretically derive the frequency-dependent electron/current flow rate. Our analysis takes in to account the quantum dynamics of electrons inside the nanorods under a periodic optical perturbation that are confined by nanorod boundaries, modelled as finite cylindrical potential wells. The influence of design parameters, such as geometric difference between the two nanorods, their volumes and the barrier width on quality parameters such as frequency-sensitivity of the current flow direction, magnitude of the current flow, positive to negative current ratio, and the energy conversion efficiency is discussed by considering a device made of Ag/TiO2/Ag. Theoretical insight and design guidelines presented here are useful for customizing our proposed CDSD for applications such as self-powered logic gates, power supplies, and sensors.

A self-discharge model of Lithium-Sulfur batteries based on direct shuttle current measurement

DEFF Research Database (Denmark)

Knap, Vaclav; Stroe, Daniel Loan; Swierczynski, Maciej Jozef

2016-01-01

. A simple but comprehensive mathematical model of the Li-S battery cell self-discharge based on the shuttle current was developed and is presented. The shuttle current values for the model parameterization were obtained from the direct shuttle current measurements. Furthermore, the battery cell depth......-of-discharge values were recomputed in order to account for the influence of the self-discharge and provide a higher accuracy of the model. Finally, the derived model was successfully validated against laboratory experiments at various conditions....

A method for crack profiles identification in eddy current testing by the multi-directional scan

International Nuclear Information System (INIS)

Kojima, Fumio; Ikeda, Takuya; Nguyen, Doung

2006-01-01

This paper is concerned with a method for identification of crack shape in conducting materials. Multi-directional scanning strategies using Eddy Current Testing is performed for sizing complex natural crackings. Two dimensional measurements by means of multi-directional scan are used in a output least square identifications. (author)

Effects of neglecting carrier tunneling on electrostatic potential in calculating direct tunneling gate current in deep submicron MOSFETs

OpenAIRE

Hakim, MMA; Haque, A

2002-01-01

We investigate the validity of the assumption of neglecting carrier tunneling effects on self-consistent electrostatic potential in calculating direct tunneling gate current in deep submicron MOSFETs. Comparison between simulated and experimental results shows that for accurate modeling of direct tunneling current, tunneling effects on potential profile need to be considered. The relative error in gate current due to neglecting carrier tunneling is higher at higher gate voltages and increases...

Direct current microhollow cathode discharges on silicon devices operating in argon and helium

Science.gov (United States)

Michaud, R.; Felix, V.; Stolz, A.; Aubry, O.; Lefaucheux, P.; Dzikowski, S.; Schulz-von der Gathen, V.; Overzet, L. J.; Dussart, R.

2018-02-01

Microhollow cathode discharges have been produced on silicon platforms using processes usually used for MEMS fabrication. Microreactors consist of 100 or 150 μm-diameter cavities made from Ni and SiO2 film layers deposited on a silicon substrate. They were studied in the direct current operating mode in two different geometries: planar and cavity configuration. Currents in the order of 1 mA could be injected in microdischarges operating in different gases such as argon and helium at a working pressure between 130 and 1000 mbar. When silicon was used as a cathode, the microdischarge operation was very unstable in both geometry configurations. Strong current spikes were produced and the microreactor lifetime was quite short. We evidenced the fast formation of blisters at the silicon surface which are responsible for the production of these high current pulses. EDX analysis showed that these blisters are filled with argon and indicate that an implantation mechanism is at the origin of this surface modification. Reversing the polarity of the microdischarge makes the discharge operate stably without current spikes, but the discharge appearance is quite different from the one obtained in direct polarity with the silicon cathode. By coating the silicon cathode with a 500 nm-thick nickel layer, the microdischarge becomes very stable with a much longer lifetime. No current spikes are observed and the cathode surface remains quite smooth compared to the one obtained without coating. Finally, arrays of 76 and 576 microdischarges were successfully ignited and studied in argon. At a working pressure of 130 mbar, all microdischarges are simultaneously ignited whereas they ignite one by one at higher pressure.

Current and Emerging Directions in the Treatment of Eating Disorders

Directory of Open Access Journals (Sweden)

Tiffany A. Brown

2012-01-01

Full Text Available Eating disorders are a significant source of psychiatric morbidity in young women and demonstrate high comorbidity with mood, anxiety, and substance use disorders. Thus, clinicians may encounter eating disorders in the context of treating other conditions. This review summarizes the efficacy of current and emerging treatments for anorexia nervosa (AN, bulimia nervosa (BN, and binge eating disorder (BED. Treatment trials were identified using electronic and manual searches and by reviewing abstracts from conference proceedings. Family based therapy has demonstrated superiority for adolescents with AN but no treatment has established superiority for adults. For BN, both 60 mg fluoxetine and cognitive behavioral therapy (CBT have well-established efficacy. For BED, selective serotonin reuptake inhibitors, CBT, and interpersonal psychotherapy have demonstrated efficacy. Emerging directions for AN include investigation of the antipsychotic olanzapine and several novel psychosocial treatments. Future directions for BN and BED include increasing CBT disseminability, targeting affect regulation, and individualized stepped-care approaches.

Counteracting fatigue in multiple sclerosis with right parietal anodal transcranial direct current stimulation

NARCIS (Netherlands)

Hanken, K.; Bosse, M.; Möhrke, K.; Eling, P.A.T.M.; Kastrup, A.; Antal, A.; Hildebrandt, H.

2016-01-01

Background: Fatigue in multiple sclerosis (MS) patients appears to correlate with vigilance decrement as reflected in an increase in reaction time and errors with prolonged time-on-task. Objectives: The aim of this study was to investigate whether anodal transcranial direct current stimulation

On-Line Monitoring of Environment-Assisted Cracking in Nuclear Piping Using Array Probe Direct Current Potential Drop

OpenAIRE

Kim, Y.; Choi, S.; Yoon, J. Y.; Nam, W. C.; Hwang, I. S.; Bromberg, Leslie; Stahle, Peter W; Ballinger, Ronald G

2015-01-01

A direct current potential drop method utilizing array probes with measurement ends maintaining an equalized potential designated as equi-potential switching array probe direct current potential drop (ESAP-DCPD) technique has been developed earlier at Seoul National University. This paper validates ESAP-DCPD technique by showing consistency among experimental measurements, analytical solution and numerical predictions using finite element analysis (FEA) of electric field changes with crack gr...

Optical gain in colloidal quantum dots achieved with direct-current electrical pumping

Science.gov (United States)

Lim, Jaehoon; Park, Young-Shin; Klimov, Victor I.

2018-01-01

Chemically synthesized semiconductor quantum dots (QDs) can potentially enable solution-processable laser diodes with a wide range of operational wavelengths, yet demonstrations of lasing from the QDs are still at the laboratory stage. An important challenge--realization of lasing with electrical injection--remains unresolved, largely due to fast nonradiative Auger recombination of multicarrier states that represent gain-active species in the QDs. Here we present population inversion and optical gain in colloidal nanocrystals realized with direct-current electrical pumping. Using continuously graded QDs, we achieve a considerable suppression of Auger decay such that it can be outpaced by electrical injection. Further, we apply a special current-focusing device architecture, which allows us to produce high current densities (j) up to ~18 A cm-2 without damaging either the QDs or the injection layers. The quantitative analysis of electroluminescence and current-modulated transmission spectra indicates that with j = 3-4 A cm-2 we achieve the population inversion of the band-edge states.

Energetic Charged-Particle Phenomena in the Jovian Magnetosphere: First Results from the Ulysses COSPIN Collaboration.

Science.gov (United States)

Simpson, J A; Anglin, J D; Balogh, A; Burrows, J R; Cowley, S W; Ferrando, P; Heber, B; Hynds, R J; Kunow, H; Marsden, R G; McKibben, R B; Müller-Mellin, R; Page, D E; Raviart, A; Sanderson, T R; Staines, K; Wenzel, K P; Wilson, M D; Zhang, M

1992-09-11

The Ulysses spacecraft made the first exploration of the region of Jupiter's magnetosphere at high Jovigraphic latitudes ( approximately 37 degrees south) on the dusk side and reached higher magnetic latitudes ( approximately 49 degrees north) on the day side than any previous mission to Jupiter. The cosmic and solar particle investigations (COSPIN) instrumentation achieved a remarkably well integrated set of observations of energetic charged particles in the energy ranges of approximately 1 to 170 megaelectron volts for electrons and 0.3 to 20 megaelectron volts for protons and heavier nuclei. The new findings include (i) an apparent polar cap region in the northern hemisphere in which energetic charged particles following Jovian magnetic field lines may have direct access to the interplanetary medium, (ii) high-energy electron bursts (rise times approximately 17 megaelectron volts) on the dusk side that are apparently associated with field-aligned currents and radio burst emissions, (iii) persistence of the global 10-hour relativistic electron "clock" phenomenon throughout Jupiter's magnetosphere, (iv) on the basis of charged-particle measurements, apparent dragging of magnetic field lines at large radii in the dusk sector toward the tail, and (v) consistent outflow of megaelectron volt electrons and large-scale departures from corotation for nucleons.

A Comparison of Alternating Current and Direct Current Electrospray Ionization for Mass Spectrometry

Science.gov (United States)

Sarver, Scott A.; Chetwani, Nishant; Dovichi, Norman J.; Go, David B.; Gartner, Carlos A.

2014-04-01

A series of studies comparing the performance of alternating current electrospray ionization (AC ESI) mass spectrometry (MS) and direct current electrospray ionization (DC ESI) MS have been conducted, exploring the absolute signal intensity and signal-to-background ratios produced by both methods using caffeine and a model peptide as targets. Because the high-voltage AC signal was more susceptible to generating gas discharges, the operating voltage range of AC ESI was significantly smaller than that for DC ESI, such that the absolute signal intensities produced by DC ESI at peak voltages were one to two orders of magnitude greater than those for AC ESI. Using an electronegative nebulizing gas, sulfur hexafluoride (SF6), instead of nitrogen (N2) increased the operating range of AC ESI by ~50 %, but did not appreciably improve signal intensities. While DC ESI generated far greater signal intensities, both ionization methods produced comparable signal-to-background noise, with AC ESI spectra appearing qualitatively cleaner. A quantitative calibration analysis was performed for two analytes, caffeine and the peptide MRFA. AC ESI utilizing SF6 outperforms all other techniques for the detection of MRFA, producing chromatographic limits of detection nearly one order of magnitude lower than that of DC ESI utilizing N2, and one-half that of DC ESI utilizing SF6. However, DC ESI outperforms AC ESI for the analysis of caffeine, indicating that improvements in spectral quality may benefit certain compounds or classes of compounds, on an individual basis.

Comparative studies of high-frequency and direct current molecular gas discharges

International Nuclear Information System (INIS)

Goichman, V.H.; Goldfarb, V.M.; Tendler, M.B.

1975-01-01

Electron gas parameters, gas temperatures, ionization and thermal instability are found to be markedly different in direct current glow discharges from capactive electrodless high frequency discharge even when equal net power input is provided. It is reasonable to expect that the combined discharge containing both types of discharges mentioned above may be expected to improve significantly both the steady-state and transient characteristics of the plasma. The characteristics of different discharges in air, nitrogen air-CO 2 -He mixture have been compared. Because of the lack of the direct electrical methods for measurements of the hf plasma, exphasis in this investigation has been laid on both theoretical) based on the analytical expression for electron energy distribution function received previously and experimental spectroscopic evaluations of the plasma parameters. (Auth.)

Mapping geological structures in bedrock via large-scale direct current resistivity and time-domain induced polarization tomography

DEFF Research Database (Denmark)

Rossi, Matteo; Olsson, Per-Ivar; Johansson, Sara

2017-01-01

-current resistivity distribution of the subsoil and the phase of the complex conductivity using a constant-phase angle model. The joint interpretation of electrical resistivity and induced-polarization models leads to a better understanding of complex three-dimensional subsoil geometries. The results have been......An investigation of geological conditions is always a key point for planning infrastructure constructions. Bedrock surface and rock quality must be estimated carefully in the designing process of infrastructures. A large direct-current resistivity and time-domain induced-polarization survey has......, there are northwest-trending Permian dolerite dykes that are less deformed. Four 2D direct-current resistivity and time-domain induced-polarization profiles of about 1-km length have been carefully pre-processed to retrieve time-domain induced polarization responses and inverted to obtain the direct...

Online effects of transcranial direct current stimulation on prefrontal metabolites in gambling disorder.

Science.gov (United States)

Dickler, Maya; Lenglos, Christophe; Renauld, Emmanuelle; Ferland, Francine; Edden, Richard A; Leblond, Jean; Fecteau, Shirley

2018-03-15

Gambling disorder is characterized by persistent maladaptive gambling behaviors and is now considered among substance-related and addictive disorders. There is still unmet therapeutic need for these clinical populations, however recent advances indicate that interventions targeting the Glutamatergic/GABAergic system hold promise in reducing symptoms in substance-related and addictive disorders, including gambling disorder. There is some data indicating that transcranial direct current stimulation may hold clinical benefits in substance use disorders and modulate levels of brain metabolites including glutamate and GABA. The goal of the present work was to test whether this non-invasive neurostimulation method modulates key metabolites in gambling disorder. We conducted a sham-controlled, crossover, randomized study, blinded at two levels in order to characterize the effects of transcranial direct current stimulation over the dorsolateral prefrontal cortex on neural metabolites levels in sixteen patients with gambling disorder. Metabolite levels were measured with magnetic resonance spectroscopy from the right dorsolateral prefrontal cortex and the right striatum during active and sham stimulation. Active as compared to sham stimulation elevated prefrontal GABA levels. There were no significant changes between stimulation conditions in prefrontal glutamate + glutamine and N-acetyl Aspartate, or in striatal metabolite levels. Results also indicated positive correlations between metabolite levels during active, but not sham, stimulation and levels of risk taking, impulsivity and craving. Our findings suggest that transcranial direct current stimulation can modulate GABA levels in patients with gambling disorder which may represent an interesting future therapeutic avenue. Copyright © 2017 Elsevier Ltd. All rights reserved.

Early Childhood Inclusion in the United States: Goals, Current Status, and Future Directions

Science.gov (United States)

Guralnick, Michael J.; Bruder, Mary Beth

2016-01-01

The current status and future directions of early childhood inclusion in the United States are discussed from the perspective of 4 key goals: access, accommodations and feasibility, developmental progress, and social integration. Recommendations are put forward to promote inclusion goals emphasizing administrative structures, personnel…

Current in the plasma moving in an arbitrary direction across a magnetic field

International Nuclear Information System (INIS)

Samokhin, M.V.

1991-01-01

Condition under which freezing-in equation is satisfied in case of arbitrarily changeable direction of rate of plasma flow across the magnetic field is considered. It is shown that in the ideally frozen-in plasma there should exist current independent on the flow rate

Comparison of dayside current layers in Venus' ionosphere and earth's equatorial electrojet

Science.gov (United States)

Cole, Keith D.

1993-01-01

The major physical aspects of the equatorial electrojet of Earth and the dayside ionospheric current layers of Venus are compared, viz., the electric current intensity and total current, roles of electric field, pressure and gravity, diffusion time scales, and the Bernouille effect. The largest potential differences, of the order of 10 volts, horizontally across the dayside ionosphere of Venus, have important implications for possible dynamo action in the Venus ionosphere and the application of an electric field from the lower atmosphere or from the solar wind. An upper limit to the horizontal scale of vertical magnetic fields in the Venus ionosphere is estimated thereby for the first time. New upper limits on the velocity in, and thickness of, a possible S layer at Venus are presented. If an S layer exists, it is only for extreme conditions of the solar wind. A mechanism for formation of magnetic ropes in the Venus ionosphere is also proposed.

Transcranial direct current stimulation in psychiatric disorders

Science.gov (United States)

Tortella, Gabriel; Casati, Roberta; Aparicio, Luana V M; Mantovani, Antonio; Senço, Natasha; D’Urso, Giordano; Brunelin, Jerome; Guarienti, Fabiana; Selingardi, Priscila Mara Lorencini; Muszkat, Débora; Junior, Bernardo de Sampaio Pereira; Valiengo, Leandro; Moffa, Adriano H; Simis, Marcel; Borrione, Lucas; Brunoni, André R

2015-01-01

The interest in non-invasive brain stimulation techniques is increasing in recent years. Among these techniques, transcranial direct current stimulation (tDCS) has been the subject of great interest among researchers because of its easiness to use, low cost, benign profile of side effects and encouraging results of research in the field. This interest has generated several studies and randomized clinical trials, particularly in psychiatry. In this review, we provide a summary of the development of the technique and its mechanism of action as well as a review of the methodological aspects of randomized clinical trials in psychiatry, including studies in affective disorders, schizophrenia, obsessive compulsive disorder, child psychiatry and substance use disorder. Finally, we provide an overview of tDCS use in cognitive enhancement as well as a discussion regarding its clinical use and regulatory and ethical issues. Although many promising results regarding tDCS efficacy were described, the total number of studies is still low, highlighting the need of further studies aiming to replicate these findings in larger samples as to provide a definite picture regarding tDCS efficacy in psychiatry. PMID:25815258

Characterizing Ductile Damage and Failure: Application of the Direct Current Potential Drop Method to Uncracked Tensile Specimens

OpenAIRE

Brinnel, V.; Döbereiner, B.; Münstermann, Sebastian

2014-01-01

Modern high-strength steels exhibit excellent ductility properties but their application is hindered by traditional design rules. A characterization of necessary safety margins for the ductile failure of these steels is therefore required. Direct observation of ductile damage within tests is currently not possible, only limited measurements can be made with synchrotron or X-ray radiation facilities. The direct current potential drop (DCPD) method can determine ductile crack propagation with l...

BEE VENOM TRAP DESIGN FOR PRODUCE BEE VENOM OF APIS MELLIFERA L. HONEY BEES

OpenAIRE

Budiaman

2015-01-01

Bee venom is one honey bee products are very expensive and are required in the pharmaceutical industry and as an anti-cancer known as nanobee, but the production technique is still done in the traditional way. The purpose of this study was to design a bee venom trap to produce bee venom of Apis mellifera L honey bees. The method used is to design several models of bee venom apparatus equipped weak current (DC current) with 3 variations of voltage, ie 12 volts, 15 volts and 18 volts coupled...

Considering the influence of stimulation parameters on the effect of conventional and high-definition transcranial direct current stimulation.

Science.gov (United States)

To, Wing Ting; Hart, John; De Ridder, Dirk; Vanneste, Sven

2016-01-01

Recently, techniques to non-invasively modulate specific brain areas gained popularity in the form of transcranial direct current stimulation (tDCS) and high-definition transcranial direct current stimulation. These non-invasive techniques have already shown promising outcomes in various studies with healthy subjects as well as patient populations. Despite widespread dissemination of tDCS, there remain significant unknowns about the influence of a diverse number of tDCS parameters (e.g. polarity, size, position of electrodes & duration of stimulation) in inducing neurophysiological and behavioral effects. This article explores both techniques starting with the history of tDCS, to the differences between conventional tDCS and high-definition transcranial direct current stimulation, the underlying physiological mechanism, the (in)direct effects, the applications of tDCS with varying parameters, the efficacy, the safety issues and the opportunities for future research.

Comments on: “Transcranial Direct Current Stimulation for Obsessive-Compulsive Disorder: A Systematic Review”

Directory of Open Access Journals (Sweden)

Mohammad Alwardat

2018-03-01

Full Text Available Dear Editor, Brunelin et al. [1] recently conducted a systematic review that evaluated the effect of applied transcranial direct current stimulation (tDCS on patients with obsessive compulsive disorder (OCD.[...

Mechanisms and Effects of Transcranial Direct Current Stimulation

Science.gov (United States)

Giordano, James; Bikson, Marom; Kappenman, Emily S.; Clark, Vincent P.; Coslett, H. Branch; Hamblin, Michael R.; Hamilton, Roy; Jankord, Ryan; Kozumbo, Walter J.; McKinley, R. Andrew; Nitsche, Michael A.; Reilly, J. Patrick; Richardson, Jessica; Wurzman, Rachel

2017-01-01

The US Air Force Office of Scientific Research convened a meeting of researchers in the fields of neuroscience, psychology, engineering, and medicine to discuss most pressing issues facing ongoing research in the field of transcranial direct current stimulation (tDCS) and related techniques. In this study, we present opinions prepared by participants of the meeting, focusing on the most promising areas of research, immediate and future goals for the field, and the potential for hormesis theory to inform tDCS research. Scientific, medical, and ethical considerations support the ongoing testing of tDCS in healthy and clinical populations, provided best protocols are used to maximize safety. Notwithstanding the need for ongoing research, promising applications include enhancing vigilance/attention in healthy volunteers, which can accelerate training and support learning. Commonly, tDCS is used as an adjunct to training/rehabilitation tasks with the goal of leftward shift in the learning/treatment effect curves. Although trials are encouraging, elucidating the basic mechanisms of tDCS will accelerate validation and adoption. To this end, biomarkers (eg, clinical neuroimaging and findings from animal models) can support hypotheses linking neurobiological mechanisms and behavioral effects. Dosage can be optimized using computational models of current flow and understanding dose–response. Both biomarkers and dosimetry should guide individualized interventions with the goal of reducing variability. Insights from other applied energy domains, including ionizing radiation, transcranial magnetic stimulation, and low-level laser (light) therapy, can be prudently leveraged. PMID:28210202

Sensorless optimal sinusoidal brushless direct current for hard disk drives

Science.gov (United States)

Soh, C. S.; Bi, C.

2009-04-01

Initiated by the availability of digital signal processors and emergence of new applications, market demands for permanent magnet synchronous motors have been surging. As its back-emf is sinusoidal, the drive current should also be sinusoidal for reducing the torque ripple. However, in applications like hard disk drives, brushless direct current (BLDC) drive is adopted instead of sinusoidal drive for simplification. The adoption, however, comes at the expense of increased harmonics, losses, torque pulsations, and acoustics. In this paper, we propose a sensorless optimal sinusoidal BLDC drive. First and foremost, the derivation for an optimal sinusoidal drive is presented, and a power angle control scheme is proposed to achieve an optimal sinusoidal BLDC. The scheme maintains linear relationship between the motor speed and drive voltage. In an attempt to execute the sensorless drive, an innovative power angle measurement scheme is devised, which takes advantage of the freewheeling diodes and measures the power angle through the detection of diode voltage drops. The objectives as laid out will be presented and discussed in this paper, supported by derivations, simulations, and experimental results. The proposed scheme is straightforward, brings about the benefits of sensorless sinusoidal drive, negates the need for current sensors by utilizing the freewheeling diodes, and does not incur additional cost.

Formulation of the energetic spectral distribution of in pile neutron flux (energies greater than a few hundred electron volts) (1963); Formulation des repartitions spectrales energetiques de flux neutroniques en pile (energies superieures a quelques centaines d'electrons-volts) (1963)

Energy Technology Data Exchange (ETDEWEB)

Genthon, J P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

In the present report an expression is deduced for the spectral distribution of flux of over a few hundred electron volts; it is valid for most cases of thermal neutron reactors. This expression is: {psi}(E) = K [{psi}{sub o}(E) + h {psi}{sub e}(E)] {psi}{sub o}(E) is the so-called 'homogeneous' constituent of the flux; it corresponds approximately to the case of an infinite homogeneous medium; it is of the type: Y(V - E) e{sup (b{radical}}{sup E)}/E + Y(E-V) F E{sup {upsilon}} e{sup -{beta}}{sup E} The parameters V and F are such that {psi}{sub o}(E) and its derivative are continuous at the junction energy V. {psi}{sub e}(E) is the 'heterogeneous' constituent of the flux; it is of the type: E{sup {upsilon}} e{sup -{beta}}{sup E}. The various parameters of {psi}(E) are on the one hand characteristic of the nature of the reactor moderator, and on the other hand determined by a resonant flux measurement and one, or possibly two, measurements using a fast neutron threshold detector. We have been led furthermore to define an expression for the threshold reaction section which is more exact than the conventional transition function. (author) [French] Il est etabli, dans le present rapport, une formulation {psi}(E) des repartitions spectrales de flux au-dessus de quelques centaines d'electron-s volts, valable dans la majeure partie des cas de piles dites a neutrons thermiques. Cette formulation s'exprime: {psi}(E) = K [{psi}{sub o}(E) + h {psi}{sub e}(E)] {psi}{sub o}(E) est la composante dite 'homogene' du flux; elle correspond a peu pres au cas d'un milieu infini homogene; elle est du type: Y(V - E) e{sup (b{radical}}{sup E)}/E + Y(E-V) F E{sup {upsilon}} e{sup -{beta}}{sup E} les parametres V et F sont tels que {psi}{sub o}(E) et sa derivee soient continues a l'energie de jonction V. {psi}{sub e} est la composante dite 'heterogene' du flux ; elle est du type: E{sup {upsilon}} e{sup -{beta}}{sup E}. Les differents parametres de {psi}(E) sont, d'une part

Safety and tolerability of transcranial direct current stimulation to stroke patients - A phase I current escalation study.

Science.gov (United States)

Chhatbar, Pratik Y; Chen, Rong; Deardorff, Rachael; Dellenbach, Blair; Kautz, Steven A; George, Mark S; Feng, Wuwei

A prior meta-analysis revealed that higher doses of transcranial direct current stimulation (tDCS) have a better post-stroke upper-extremity motor recovery. While this finding suggests that currents greater than the typically used 2 mA may be more efficacious, the safety and tolerability of higher currents have not been assessed in stroke patients. We aim to assess the safety and tolerability of single session of up to 4 mA in stroke patients. We adapted a traditional 3 + 3 study design with a current escalation schedule of 1»2»2.5»3»3.5»4 mA for this tDCS safety study. We administered one 30-min session of bihemispheric montage tDCS and simultaneous customary occupational therapy to patients with first-ever ischemic stroke. We assessed safety with pre-defined stopping rules and investigated tolerability through a questionnaire. Additionally, we monitored body resistance and skin temperature in real-time at the electrode contact site. Eighteen patients completed the study. The current was escalated to 4 mA without meeting the pre-defined stopping rules or causing any major safety concern. 50% of patients experienced transient skin redness without injury. No rise in temperature (range 26°C-35 °C) was noted and skin barrier function remained intact (i.e. body resistance >1 kΩ). Our phase I safety study supports that single session of bihemispheric tDCS with current up to 4 mA is safe and tolerable in stroke patients. A phase II study to further test the safety and preliminary efficacy with multi-session tDCS at 4 mA (as compared with lower current and sham stimulation) is a logical next step. ClinicalTrials.gov Identifier: NCT02763826. Copyright © 2017 Elsevier Inc. All rights reserved.

Measurements of the large-scale direct-current Earth potential and possible implications for the geomagnetic dynamo.

Science.gov (United States)

1985-07-05

The magnitude of the large-scale direct-current earth potential was measured on a section of a recently laid transatlantic telecommunications cable. Analysis of the data acquired on the 4476-kilometer cable yielded a mean direct-current potential drop of less than about 0.072 +/- 0.050 millivolts per kilometer. Interpreted in terms of a generation of the potential by the earth's geodynamo, such a small value of the mean potential implies that the toroidal and poloidal magnetic fields of the dynamo are approximately equal at the core-mantle boundary.

Current DOE direction in low-level waste management

International Nuclear Information System (INIS)

Wilhite, E.L.; Dolenc, M.R.; Shupe, M.W.; Waldo, L.C.

1989-01-01

The U.S. Department of Energy (DOE) is implementing revised DOE Order 5820.2A Radioactive Waste Management. Chapter III of the revised order provides prescriptive requirements for managing low-level waste and is the subject of this paper. The revised order requires that all DOE low-level radioactive and mixed waste be systematically managed, using an approach that considers the combination of waste management practices used in waste generation reduction, segregation, treatment, packaging, storage, and disposal. The Order defines performance objectives for protecting groundwater, for protecting against intrusion, and for maintaining adequate operational practices. A performance assessment will be required to ensure that waste management operations comply with these performance objectives. DOE implementation of the revised Order includes work in the areas of leach testing, waste stabilization, waste certification, facility monitoring, and management of unique waste streams. This paper summarizes the status of this work and the current direction DOE is taking in managing low-level waste under DOE 5820.2A

Molecular ultrasound imaging: current status and future directions

International Nuclear Information System (INIS)

Deshpande, N.; Needles, A.; Willmann, J.K.

2010-01-01

Targeted contrast-enhanced ultrasound (molecular ultrasound) is an emerging imaging strategy that combines ultrasound technology with novel molecularly-targeted ultrasound contrast agents for assessing biological processes at the molecular level. Molecular ultrasound contrast agents are nano- or micro-sized particles that are targeted to specific molecular markers by adding high-affinity binding ligands onto the surface of the particles. Following intravenous administration, these targeted ultrasound contrast agents accumulate at tissue sites overexpressing specific molecular markers, thereby enhancing the ultrasound imaging signal. High spatial and temporal resolution, real-time imaging, non-invasiveness, relatively low costs, lack of ionising irradiation and wide availability of ultrasound systems are advantages compared to other molecular imaging modalities. In this article we review current concepts and future directions of molecular ultrasound imaging, including different classes of molecular ultrasound contrast agents, ongoing technical developments of pre-clinical and clinical ultrasound systems, the potential of molecular ultrasound for imaging different diseases at the molecular level, and the translation of molecular ultrasound into the clinic.

Surface EEG-Transcranial Direct Current Stimulation (tDCS) Closed-Loop System.

Science.gov (United States)

Leite, Jorge; Morales-Quezada, Leon; Carvalho, Sandra; Thibaut, Aurore; Doruk, Deniz; Chen, Chiun-Fan; Schachter, Steven C; Rotenberg, Alexander; Fregni, Felipe

2017-09-01

Conventional transcranial direct current stimulation (tDCS) protocols rely on applying electrical current at a fixed intensity and duration without using surrogate markers to direct the interventions. This has led to some mixed results; especially because tDCS induced effects may vary depending on the ongoing level of brain activity. Therefore, the objective of this preliminary study was to assess the feasibility of an EEG-triggered tDCS system based on EEG online analysis of its frequency bands. Six healthy volunteers were randomized to participate in a double-blind sham-controlled crossover design to receive a single session of 10[Formula: see text]min 2[Formula: see text]mA cathodal and sham tDCS. tDCS trigger controller was based upon an algorithm designed to detect an increase in the relative beta power of more than 200%, accompanied by a decrease of 50% or more in the relative alpha power, based on baseline EEG recordings. EEG-tDCS closed-loop-system was able to detect the predefined EEG magnitude deviation and successfully triggered the stimulation in all participants. This preliminary study represents a proof-of-concept for the development of an EEG-tDCS closed-loop system in humans. We discuss and review here different methods of closed loop system that can be considered and potential clinical applications of such system.

Contribution to the theoretical and experimental study of the electron-volt effect in N-P junctions; Contribution a l'etude theorique et experimentale de l'effet electronvoltaique dans les jonctions N-P

Energy Technology Data Exchange (ETDEWEB)

Nguyen Van, Dong [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1959-07-15

The proposed aim of this work is to study the behaviour of a semi-conducting junction under the action of {beta} radiation. These studies were directed on the one hand to direct conversion of the energy radiated by a radioactive source to electric energy usable by means of N-P junctions, and on the other hand to the kinetics of defects produced in the semi-conductor crystals by high energy {beta} rays. In the first part of this work, an attempt has been made to complete the earlier theories of the electron-volt effect in junctions by analysing the effect mathematically. This has led to a single equation containing the electrical and geometric parameters of the semi-conductor and of the junction, and the properties of the incident radiation. Apart from this, the diffusion current of the charge carriers created by the bombardment has been studied in more detail, taking into account all the factors which play a part in the expression of the efficiency of charge collection of a junction. In the second part, where experiments on the irradiation of N-P junctions have been carried out with a {sup 90}Sr-{sup 90}Y source, mention is made of the particular advantages of a gallium arsenide junction capable of operating at relatively high temperatures (in the region of 100 deg. C). The third part presents the study of defects created in a semi-conductor crystal by high-energy {beta} rays, according to the method of electron-volt effect. It is shown here that from a study of the degradation of the short-circuit current of the junction it may be possible to determine the recombination level and the probabilities of electron and hole capture, as from a study of the lifetime decay of minority carriers in a crystal of known type. Experiments on the bombardment of Ge junctions by 2 MeV electrons were performed with a Van de Graaff. Very clear anomalies of the electron-volt effect at 100 deg. K were observed. An attempt was made at interpretation of these anomalies in the junction

Boosting Cognition : Effects of Multiple-Session Transcranial Direct Current Stimulation on Working Memory

NARCIS (Netherlands)

Talsma, L.J.; Kroese, H.A.; Slagter, H.A.

Transcranial direct current stimulation (tDCS) is a promising tool for neurocognitive enhancement. Several studies have shown that just a single session of tDCS over the left dorsolateral pFC (lDLPFC) can improve the core cognitive function of working memory (WM) in healthy adults. Yet, recent

Effects of transcranial direct current stimulation for treating depression: A modeling study

DEFF Research Database (Denmark)

Csifcsák, Gábor; Boayue, Nya Mehnwolo; Puonti, Oula

2018-01-01

Background: Transcranial direct current stimulation (tDCS) above the left dorsolateral prefrontal cortex (lDLPFC) has been widely used to improve symptoms of major depressive disorder (MDD). However, the effects of different stimulation protocols in the entire frontal lobe have not been investiga......Background: Transcranial direct current stimulation (tDCS) above the left dorsolateral prefrontal cortex (lDLPFC) has been widely used to improve symptoms of major depressive disorder (MDD). However, the effects of different stimulation protocols in the entire frontal lobe have not been...... regions. We evaluated effects of seven bipolar and two multi-electrode 4 × 1 tDCS protocols. Results: For bipolar montages, EFs were of comparable strength in the lDLPFC and in the medial prefrontal cortex (MPFC). Depending on stimulation parameters, EF cortical maps varied to a considerable degree......, but were found to be similar in controls and patients. 4 × 1 montages produced more localized, albeit weaker effects. Limitations: White matter anisotropy was not modeled. The relationship between EF strength and clinical response to tDCS could not be evaluated. Conclusions: In addition to l...

Direct current stimulation of the left temporoparietal junction modulates dynamic humor appreciation.

Science.gov (United States)

Slaby, Isabella; Holmes, Amanda; Moran, Joseph M; Eddy, Marianna D; Mahoney, Caroline R; Taylor, Holly A; Brunyé, Tad T

2015-11-11

The aim of this study was to evaluate the influence of transcranial direct current stimulation targeting the left temporoparietal junction (TPJ) on humor appreciation during a dynamic video rating task. In a within-participants design, we targeted the left TPJ with anodal, cathodal, or no transcranial direct current stimulation, centered at electrode site C3 using a 4×1 targeted stimulation montage. During stimulation, participants dynamically rated a series of six stand-up comedy videos for perceived humor. We measured event-related (time-locked to crowd laughter) modulation of humor ratings as a function of stimulation condition. Results showed decreases in rated humor during anodal (vs. cathodal or none) stimulation; this pattern was evident for the majority of videos and was only partially predicted by individual differences in humor style. We discuss the possibility that upregulation of neural circuits involved in the theory of mind and empathizing with others may reduce appreciation of aggressive humor. In conclusion, the present data show that neuromodulation of the TPJ can alter the mental processes underlying humor appreciation, suggesting critical involvement of this cortical region in detecting, comprehending, and appreciating humor.

Psychological Therapies for Auditory Hallucinations (Voices): Current Status and Key Directions for Future Research

NARCIS (Netherlands)

Thomas, N.; Hayward, M.; Peters, E; van der Gaag, M.; Bentall, R.P.; Jenner, J.; Strauss, C.; Sommer, I.E.; Johns, L.C.; Varese, F.; Gracia-Montes, J.M.; Waters, F.; Dodgson, G.; McCarthy-Jones, S.

2014-01-01

This report from the International Consortium on Hallucinations Research considers the current status and future directions in research on psychological therapies targeting auditory hallucinations (hearing voices). Therapy approaches have evolved from behavioral and coping-focused interventions,

Self-deformation in a direct current driven helium jet micro discharge

International Nuclear Information System (INIS)

Xu, S. F.; Zhong, X. X.

2016-01-01

We report on the experimental observation of three dimensional self-deformation in an atmospheric micro discharge of the helium microjet through a tube into the ambient air upon a water electrode. The geometry of the discharge system is axial symmetric. While decreasing the discharge current, three dimensional collective motion of plasma filaments is directly observed. The three dimensional configuration of the discharge self changed from an axial symmetrical horn to a rectangular horn when the water acts as a cathode

Hybrid indirect/direct contactor for thermal management of counter-current processes

Science.gov (United States)

Hornbostel, Marc D.; Krishnan, Gopala N.; Sanjurjo, Angel

2018-03-20

The invention relates to contactors suitable for use, for example, in manufacturing and chemical refinement processes. In an aspect is a hybrid indirect/direct contactor for thermal management of counter-current processes, the contactor comprising a vertical reactor column, an array of interconnected heat transfer tubes within the reactor column, and a plurality of stream path diverters, wherein the tubes and diverters are configured to block all straight-line paths from the top to bottom ends of the reactor column.

Self-deformation in a direct current driven helium jet micro discharge

Energy Technology Data Exchange (ETDEWEB)

Xu, S. F.; Zhong, X. X., E-mail: xxzhong@sjtu.edu.cn [State Key Laboratory of Advanced Optical Communication Systems and Networks and Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China)

2016-01-15

We report on the experimental observation of three dimensional self-deformation in an atmospheric micro discharge of the helium microjet through a tube into the ambient air upon a water electrode. The geometry of the discharge system is axial symmetric. While decreasing the discharge current, three dimensional collective motion of plasma filaments is directly observed. The three dimensional configuration of the discharge self changed from an axial symmetrical horn to a rectangular horn when the water acts as a cathode.

Self-deformation in a direct current driven helium jet micro discharge

Science.gov (United States)

Xu, S. F.; Zhong, X. X.

2016-01-01

We report on the experimental observation of three dimensional self-deformation in an atmospheric micro discharge of the helium microjet through a tube into the ambient air upon a water electrode. The geometry of the discharge system is axial symmetric. While decreasing the discharge current, three dimensional collective motion of plasma filaments is directly observed. The three dimensional configuration of the discharge self changed from an axial symmetrical horn to a rectangular horn when the water acts as a cathode.

In-vivo Imaging of Magnetic Fields Induced by Transcranial Direct Current Stimulation (tDCS) in Human Brain using MRI

Science.gov (United States)

Jog, Mayank V.; Smith, Robert X.; Jann, Kay; Dunn, Walter; Lafon, Belen; Truong, Dennis; Wu, Allan; Parra, Lucas; Bikson, Marom; Wang, Danny J. J.

2016-10-01

Transcranial direct current stimulation (tDCS) is an emerging non-invasive neuromodulation technique that applies mA currents at the scalp to modulate cortical excitability. Here, we present a novel magnetic resonance imaging (MRI) technique, which detects magnetic fields induced by tDCS currents. This technique is based on Ampere’s law and exploits the linear relationship between direct current and induced magnetic fields. Following validation on a phantom with a known path of electric current and induced magnetic field, the proposed MRI technique was applied to a human limb (to demonstrate in-vivo feasibility using simple biological tissue) and human heads (to demonstrate feasibility in standard tDCS applications). The results show that the proposed technique detects tDCS induced magnetic fields as small as a nanotesla at millimeter spatial resolution. Through measurements of magnetic fields linearly proportional to the applied tDCS current, our approach opens a new avenue for direct in-vivo visualization of tDCS target engagement.

Direct Reconstruction of Two-Dimensional Currents in Thin Films from Magnetic-Field Measurements

Science.gov (United States)

Meltzer, Alexander Y.; Levin, Eitan; Zeldov, Eli

2017-12-01

An accurate determination of microscopic transport and magnetization currents is of central importance for the study of the electric properties of low-dimensional materials and interfaces, of superconducting thin films, and of electronic devices. Current distribution is usually derived from the measurement of the perpendicular component of the magnetic field above the surface of the sample, followed by numerical inversion of the Biot-Savart law. The inversion is commonly obtained by deriving the current stream function g , which is then differentiated in order to obtain the current distribution. However, this two-step procedure requires filtering at each step and, as a result, oversmooths the solution. To avoid this oversmoothing, we develop a direct procedure for inversion of the magnetic field that avoids use of the stream function. This approach provides enhanced accuracy of current reconstruction over a wide range of noise levels. We further introduce a reflection procedure that allows for the reconstruction of currents that cross the boundaries of the measurement window. The effectiveness of our approach is demonstrated by several numerical examples.

Transcranial direct current stimulation may modulate extinction memory in posttraumatic stress disorder

OpenAIRE

van?t Wout, Mascha; Longo, Sharon M.; Reddy, Madhavi K.; Philip, Noah S.; Bowker, Marguerite T.; Greenberg, Benjamin D.

2017-01-01

Abstract Background Abnormalities in fear extinction and recall are core components of posttraumatic stress disorder (PTSD). Data from animal and human studies point to a role of the ventromedial prefrontal cortex (vmPFC) in extinction learning and subsequent retention of extinction memories. Given the increasing interest in developing noninvasive brain stimulation protocols for psychopathology treatment, we piloted whether transcranial direct current stimulation (tDCS) during extinction lear...

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

Directory of Open Access Journals (Sweden)

Yean-Der Kuan

2014-05-01

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

Joint Inversion of Direct Current Resistivity and Seismic Refraction Data

International Nuclear Information System (INIS)

Kurt, B.B.

2007-01-01

In this study, I assumed the underground consist of horizontal layers. I developed one-dimensional (1D) Direct Current Resistivity (DCR) and seismic refraction inversion code using MATLAB package and attempt to find velocity, resistivity and depth of the layers. The code uses damped least square technique. The code can do inversion on DCR and seismic data either individually or jointly. I tested the joint inversion code on synthetic data. Eventually, I saw that the result of joint inversion is better than the result of individual inversions. The joint inversion found depth of models of each layer and, in addition, velocity and resistivity closer to real values

Improving CANDU annunciation - Current R and D and future directions

International Nuclear Information System (INIS)

Lupton, L.R.; Feher, M.P.; Davey, E.C.; Guo, K.Q.; Bhuiyan, S.H.

1994-01-01

Annunciation is used to ensure that control room staff are promptly alerted to important changes in plant conditions that may impact on safety and production goals. We are carrying out research and development to improve CANDU annunciation, in partnership with Canadian CANDU utility and design organizations. The main goal is to solve the ''information overload'' problem that occurs during major plant upsets, while providing operators with annunciation information needed to prevent, mitigate, and accommodate plant disturbances. To data, a set of annunciation concepts has been developed based on operational needs in a complex supervisory control environment. A prototype annunciation system has been developed and demonstrated with Point Lepreau Generating Station operations staff. Preliminary evaluations show that the system has the potential to solve many of the current problems associated with upset management. Further evaluation of this system is planned for 1994/95. This paper summarizes the project, including the current status, lessons learned to data, future directions of the research, and implementation by plants. (author). 9 refs, 3 figs, 1 tab

Experimental Investigation of a Direct Methanol Fuel Cell with Hilbert Fractal Current Collectors

Directory of Open Access Journals (Sweden)

Jing-Yi Chang

2014-01-01

Full Text Available The Hilbert curve is a continuous type of fractal space-filling curve. This fractal curve visits every point in a square grid with a size of 2×2, 4×4, or any other power of two. This paper presents Hilbert fractal curve application to direct methanol fuel cell (DMFC current collectors. The current collectors are carved following first, second, and third order Hilbert fractal curves. These curves give the current collectors different free open ratios and opening perimeters. We conducted an experimental investigation into DMFC performance as a function of the free open ratio and opening perimeter on the bipolar plates. Nyquist plots of the bipolar plates are made and compared using electrochemical impedance spectroscopy (EIS experiments to understand the phenomena in depth. The results obtained in this paper could be a good reference for future current collector design.

Resistivity measurements using a direct current induction method (1963)

International Nuclear Information System (INIS)

Delaplace, J.; Hillairet, J.

1964-01-01

The conventional methods for measuring electrical resistivities necessitate the fixing of electrical contacts on the sample either mechanically or by soldering. Furthermore it is also necessary to carry,out the measurements on low cross-section samples which are not always easy to obtain. Our direct-current induction method on the other hand requires no contacts and can easily be applied to samples of large cross-section. The sample is placed in a uniform magnetic field; at the moment when the current is cut, eddy currents appear in the sample which tend to oppose the disappearance of the field. The way in which the magnetic flux decreases in the sample makes it possible to determine the resistivity of the material. This method has been applied to samples having diameters of between 1 and 30 mm in the case of metals which are good conductors. It gives a value for the local resistivity and makes it possible to detect any variation along a sample. The measurements can be carried out at all temperature from a few degrees absolute to 500 deg. C. We have used the induction method to follow the purification of beryllium by zone-melting; it is in effect possible to estimate the purity of a material by resistivity measurements. We have measured the resistivity along each bar treated by the zone-melting technique and have thus, localised the purest section. High temperature measurements have been carried out on uranium carbide and on iron-aluminium alloys. This method constitutes an interesting means of investigation the resistivity of solid materials. Its accuracy and rapidity make it particularly adapted both to fundamental research and to production control. (authors) [fr

Electrochemical deposition and characterization of zinc–nickel alloys deposited by direct and reverse current

Directory of Open Access Journals (Sweden)

JELENA B. BAJAT

2005-12-01

Full Text Available Zn–Ni alloys electrochemically deposited on steel under various deposition conditions were investigated. The alloys were deposited on a rotating disc electrode and on a steel panel from chloride solutions by direct and reverse current. The influence of reverse plating variables (cathodic and anodic current densities and their time duration on the composition, phase structure and corrosion properties were investigated. The chemical content and phase composition affect the anticorrosive properties of Zn–Ni alloys during exposure to a corrosive agent (3 % NaCl solution. It was shown that the Zn–Ni alloy electrodeposited by reverse current with a full period T = 1 s and r = 0.2 exhibits the best corrosion properties of all the investigated alloys deposited by reverse current.

Direct current plasma jet at atmospheric pressure operating in nitrogen and air

Science.gov (United States)

Deng, X. L.; Nikiforov, A. Yu.; Vanraes, P.; Leys, Ch.

2013-01-01

An atmospheric pressure direct current (DC) plasma jet is investigated in N2 and dry air in terms of plasma properties and generation of active species in the active zone and the afterglow. The influence of working gases and the discharge current on plasma parameters and afterglow properties are studied. The electrical diagnostics show that discharge can be sustained in two different operating modes, depending on the current range: a self-pulsing regime at low current and a glow regime at high current. The gas temperature and the N2 vibrational temperature in the active zone of the jet and in the afterglow are determined by means of emission spectroscopy, based on fitting spectra of N2 second positive system (C3Π-B3Π) and the Boltzmann plot method, respectively. The spectra and temperature differences between the N2 and the air plasma jet are presented and analyzed. Space-resolved ozone and nitric oxide density measurements are carried out in the afterglow of the jet. The density of ozone, which is formed in the afterglow of nitrogen plasma jet, is quantitatively detected by an ozone monitor. The density of nitric oxide, which is generated only in the air plasma jet, is determined by means of mass-spectroscopy techniques.

Hybrid Direct-Current Circuit Breaker

Science.gov (United States)

Wang, Ruxi (Inventor); Premerlani, William James (Inventor); Caiafa, Antonio (Inventor); Pan, Yan (Inventor)

2017-01-01

A circuit breaking system includes a first branch including at least one solid-state snubber; a second branch coupled in parallel to the first branch and including a superconductor and a cryogenic contactor coupled in series; and a controller operatively coupled to the at least one solid-state snubber and the cryogenic contactor and programmed to, when a fault occurs in the load circuit, activate the at least one solid-state snubber for migrating flow of the electrical current from the second branch to the first branch, and, when the fault is cleared in the load circuit, activate the cryogenic contactor for migrating the flow of the electrical current from the first branch to the second branch.

A clinical trial with combined transcranial direct current stimulation and alcohol approach bias retraining

NARCIS (Netherlands)

den Uyl, T.E.; Gladwin, T.E.; Rinck, M.; Lindenmeyer, J.; Wiers, R.W.

2017-01-01

Two studies showed an improvement in clinical outcomes after alcohol approach bias retraining, a form of Cognitive Bias Modification (CBM). We investigated whether transcranial direct current stimulation (tDCS) could enhance effects of CBM. TDCS is a neuromodulation technique that can increase

Visualizing Transcranial Direct Current Stimulation (tDCS) in vivo using Magnetic Resonance Imaging

Science.gov (United States)

Jog, Mayank Anant

Transcranial Direct Current Stimulation (tDCS) is a low-cost, non-invasive neuromodulation technique that has been shown to treat clinical symptoms as well as improve cognition. However, no techniques exist at the time of research to visualize tDCS currents in vivo. This dissertation presents the theoretical framework and experimental implementations of a novel MRI technique that enables non-invasive visualization of the tDCS electric current using magnetic field mapping. The first chapter establishes the feasibility of measuring magnetic fields induced by tDCS currents. The following chapter discusses the state of the art implementation that can measure magnetic field changes in individual subjects undergoing concurrent tDCS/MRI. The final chapter discusses how the developed technique was integrated with BOLD fMRI-an established MRI technique for measuring brain function. By enabling a concurrent measurement of the tDCS current induced magnetic field as well as the brain's hemodynamic response to tDCS, our technique opens a new avenue to investigate tDCS mechanisms and improve targeting.

Statistical mechanical characteristics of slip-ring induction motors when direct current braking

Energy Technology Data Exchange (ETDEWEB)

Kedzior, W; Muchorowski, J; Pienkowski, K

1980-09-01

This paper evaluates methods of braking high capacity belt conveyors used in brown coal surface mines in Poland. Complications associated with belt conveyor braking, particularly when a conveyor moves down a slope, are analyzed. A method of calculating mechanical characteristics of wound-rotor induction motors during direct current braking taking into account saturation of magnetic circuit is presented. Characteristics of the SZUr motor with 630 kW power, used in brown coal mining, are also given. Analyses show that motor operation can be efficiently braked in two ways: 1. by changing additional resistance in rotor circuit (e.g. using thyristor controller); 2. by changing intensity of electric current supplied to stator winding (e.g. using a rectifier). (3 refs.) (In Polish)

Transcranial direct current stimulation in patients with Alzheimer’s disease: Challenges and responses

Directory of Open Access Journals (Sweden)

Hong Yuan

2015-09-01

Full Text Available The use of transcranial direct current stimulation (tDCS as a noninvasive therapeutic approach for Alzheimer’s disease (AD has gained increasing attention. Research regarding the utility of tDCS in AD is inconsistent. In this study, we reviewed the importance of individual diversity among AD patients, starting from the uninformative mean results. We also demonstrated variation among AD patients. Highly educated patients seem to benefit more; education also seems to modulate baseline measurements and the results. Individual cortical morphology also affects the current distribution, which influences the effectiveness of stimulation. We suggest the use of structural MRI to distinguish inter-individual variability; high-resolution modeling can also be used to predict current distributions and should be combined with cognitive training (CT along with tDCS.

Improving Naming Abilities among Healthy Young-Old Adults Using Transcranial Direct Current Stimulation

Science.gov (United States)

Lifshitz-Ben-Basat, Adi; Mashal, Nira

2018-01-01

Transcranial direct current stimulation (tDCS) is a noninvasive tool to facilitate brain plasticity and enhance language abilities. Our study aims to search for a potential beneficial influence of tDCS on a cognitive linguistic task of naming which found to decline during aging. A group of fifteen healthy old adults (M = 64.93 ± 5.09 years) were…

Effect of Cathodal Transcranial Direct Current Stimulation on a Child with Involuntary Movement after Hypoxic Encephalopathy

Directory of Open Access Journals (Sweden)

Mayumi Nagai

2018-01-01

Full Text Available The aim of the study was to investigate the effect of cathodal transcranial direct current stimulation to the supplementary motor area to inhibit involuntary movements of a child. An 8-year-old boy who developed hypoxic encephalopathy after asphyxia at the age of 2 had difficulty in remaining standing without support because of involuntary movements. He was instructed to remain standing with his plastic ankle-foot orthosis for 10 s at three time points by leaning forward with his forearms on a desk. He received cathodal or sham transcranial direct current stimulation to the supplementary motor area at 1 mA for 10 min. Involuntary movements during standing were measured using an accelerometer attached to his forehead. The low-frequency power of involuntary movements during cathodal transcranial direct current stimulation significantly decreased compared with that during sham stimulation. No adverse effects were observed. Involuntary movement reduction by cathodal stimulation to supplementary motor areas suggests that stimulations modulated the corticobasal ganglia motor circuit. Cathodal stimulation to supplementary motor areas may be effective for reducing involuntary movements and may be safely applied to children with movement disorders.

Current direction, temperature, and salinity data from moored current meter casts in the North Pacific Ocean from 1983-06-01 to 1983-08-01 (NODC Accession 8500147)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, temperature, and salinity data were collected using moored current meter casts in the North Pacific Ocean from June 1, 1983 to August 1, 1983....

Fundamental properties of field emission-driven direct current microdischarges

International Nuclear Information System (INIS)

Rumbach, Paul; Go, David B.

2012-01-01

For half a century, it has been known that the onset of field emission in direct current microdischarges with gap sizes less than 10 μm can lead to breakdown at applied voltages far less than predicted by Paschen's law. It is still unclear how field emission affects other fundamental plasma properties at this scale. In this work, a one-dimensional fluid model is used to predict basic scaling laws for fundamental properties including ion density, electric field due to space charge, and current-voltage relations in the pre-breakdown regime. Computational results are compared with approximate analytic solutions. It is shown that field emission provides an abundance of cathode electrons, which in turn create large ion concentrations through ionizing collisions well before Paschen's criterion for breakdown is met. Breakdown due to ion-enhanced field emission occurs when the electric field due to space charge becomes comparable to the applied electric field. Simple scaling analysis of the 1D Poisson equation demonstrates that an ion density of n + ≈ 0.1V A ε 0 /qd 2 is necessary to significantly distort the electric field. Defining breakdown in terms of this critical ion density leads analytically to a simple, effective secondary emission coefficient γ ′ of the same mathematical form initially suggested by Boyle and Kisliuk [Phys. Rev. 97, 255 (1955)].

Trans-spinal direct current stimulation for the modulation of the lumbar spinal motor networks

NARCIS (Netherlands)

Kuck, Alexander

2018-01-01

Trans-spinal Direct Current Stimulation (tsDCS) is a noninvasive neuromodulatory tool for the modulation of the spinal neurocircuitry. Initial studies have shown that tsDCS is able to induce a significant and lasting change in spinal-reflex- and corticospinal information processing. It is therefore

Direct current hopping conductance in one-dimensional diagonal disordered systems

Institute of Scientific and Technical Information of China (English)

Ma Song-Shan; Xu Hui; Liu Xiao-Liang; Xiao Jian-Rong

2006-01-01

Based on a tight-binding disordered model describing a single electron band, we establish a direct current (dc) electronic hopping transport conductance model of one-dimensional diagonal disordered systems, and also derive a dc conductance formula. By calculating the dc conductivity, the relationships between electric field and conductivity and between temperature and conductivity are analysed, and the role played by the degree of disorder in electronic transport is studied. The results indicate the conductivity of systems decreasing with the increase of the degree of disorder, characteristics of negative differential dependence of resistance on temperature at low temperatures in diagonal disordered systems, and the conductivity of systems decreasing with the increase of electric field, featuring the non-Ohm's law conductivity.

Testing for causality between the foreign direct investment, current account deficit, GDP and total credit: Evidence from G7

Directory of Open Access Journals (Sweden)

Akbas Yusuf Ekrem

2013-01-01

Full Text Available In this study, countries were analyzed between 1990 and 2011 in order to determine whether a causal relationship exists among current account deficit, GDP, foreign direct investment, and total credits of G7. Analysis took into account the cross-sectional dependence and was applied to test the causality among the variables form the panel. Firstly, panel unit root tests were used for determining stationary of variables. As a result of the panel unit root tests, it was found that GDP and foreign direct investment have a stationary structure and that total credits and current account deficit contain unit root. In order to see whether there is a long-term relationship among the variables or not, the panel co-integration test was used. As a result of the test, it was concluded that there is a co-integration relationship among the series. The possibility of a causal relationship was analyzed among the variables using the causality test developed by Elena Ivona Dumitrescu and Christophe Hurlin (2012. Results of the analysis showed a unidirectional causal relationship from current account deficit and foreign direct investment to GDP. Bidirectional causality was found between current account deficit and total credits. Finally, a unidirectional relationship was found from foreign direct investment to current account deficit and total credits.

Current direction and CTD data from moored current meter and CTD casts in the Delaware Bay from 1984-01-01 to 1984-12-01 (NODC Accession 8600001)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction and CTD data were collected using moored current meter and CTD casts in the Delaware Bay from January 1, 1984 to December 1, 1985. Data were...

Current direction and CTD data from moored current meter and CTD casts in the Atlantic Ocean from 1980-08-04 to 1981-08-14 (NODC Accession 8200240)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction and CTD data were collected using moored current meter and CTD casts in the Atlantic Ocean from August 4, 1980 to August 14, 1981. Data were...

Efficacy of transcranial direct-current stimulation (tDCS) in women with provoked vestibulodynia: study protocol for a randomized controlled trial.

Science.gov (United States)

Morin, Annie; Léonard, Guillaume; Gougeon, Véronique; Waddell, Guy; Bureau, Yves-André; Girard, Isabelle; Morin, Mélanie

2016-05-14

Provoked vestibulodynia is the most common form of vulvodynia. Despite its high prevalence and deleterious sexual, conjugal, and psychological repercussions, effective evidence-based interventions for provoked vestibulodynia remain limited. For a high proportion of women, significant pain persists despite the currently available treatments. Growing evidence suggests that the central nervous system (CNS) could play a key role in provoked vestibulodynia; thus, treatment targeting the CNS, rather than localized dysfunctions, may be beneficial for women suffering from provoked vestibulodynia. In this study, we aim to build on the promising results of a previous case report and evaluate whether transcranial direct-current stimulation, a non-invasive brain stimulation technique targeting the CNS, could be an effective treatment option for women with provoked vestibulodynia. This single-center, triple-blind, parallel group, randomized, controlled trial aims to compare the efficacy of transcranial direct-current stimulation with sham transcranial direct-current stimulation in women with provoked vestibulodynia. Forty women diagnosed with provoked vestibulodynia by a gynecologist, following a standardized treatment protocol, are randomized to either active transcranial direct-current stimulation treatment for ten sessions of 20 minutes at an intensity of 2 mA or sham transcranial direct-current stimulation over a 2-week period. Outcome measures are collected at baseline, 2 weeks after treatment and at 3-month follow-up. The primary outcome is pain during intercourse, assessed with a numerical rating scale. Secondary measurements focus on the sexual function, vestibular pain sensitivity, psychological distress, treatment satisfaction, and the patient's global impression of change. To our knowledge, this study is the first randomized controlled trial to examine the efficacy of transcranial direct-current stimulation in women with provoked vestibulodynia. Findings from this

Contribution to the theoretical and experimental study of the electron-volt effect in N-P junctions; Contribution a l'etude theorique et experimentale de l'effet electronvoltaique dans les jonctions N-P

Energy Technology Data Exchange (ETDEWEB)

Nguyen Van, Dong [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1959-07-15

The proposed aim of this work is to study the behaviour of a semi-conducting junction under the action of {beta} radiation. These studies were directed on the one hand to direct conversion of the energy radiated by a radioactive source to electric energy usable by means of N-P junctions, and on the other hand to the kinetics of defects produced in the semi-conductor crystals by high energy {beta} rays. In the first part of this work, an attempt has been made to complete the earlier theories of the electron-volt effect in junctions by analysing the effect mathematically. This has led to a single equation containing the electrical and geometric parameters of the semi-conductor and of the junction, and the properties of the incident radiation. Apart from this, the diffusion current of the charge carriers created by the bombardment has been studied in more detail, taking into account all the factors which play a part in the expression of the efficiency of charge collection of a junction. In the second part, where experiments on the irradiation of N-P junctions have been carried out with a {sup 90}Sr-{sup 90}Y source, mention is made of the particular advantages of a gallium arsenide junction capable of operating at relatively high temperatures (in the region of 100 deg. C). The third part presents the study of defects created in a semi-conductor crystal by high-energy {beta} rays, according to the method of electron-volt effect. It is shown here that from a study of the degradation of the short-circuit current of the junction it may be possible to determine the recombination level and the probabilities of electron and hole capture, as from a study of the lifetime decay of minority carriers in a crystal of known type. Experiments on the bombardment of Ge junctions by 2 MeV electrons were performed with a Van de Graaff. Very clear anomalies of the electron-volt effect at 100 deg. K were observed. An attempt was made at interpretation of these anomalies in the junction

Direct current magnetron sputter-deposited ZnO thin films

International Nuclear Information System (INIS)

Hoon, Jian-Wei; Chan, Kah-Yoong; Krishnasamy, Jegenathan; Tou, Teck-Yong; Knipp, Dietmar

2011-01-01

Zinc oxide (ZnO) is a very promising electronic material for emerging transparent large-area electronic applications including thin-film sensors, transistors and solar cells. We fabricated ZnO thin films by employing direct current (DC) magnetron sputtering deposition technique. ZnO films with different thicknesses ranging from 150 nm to 750 nm were deposited on glass substrates. The deposition pressure and the substrate temperature were varied from 12 mTorr to 25 mTorr, and from room temperature to 450 deg. C, respectively. The influence of the film thickness, deposition pressure and the substrate temperature on structural and optical properties of the ZnO films was investigated using atomic force microscopy (AFM) and ultraviolet-visible (UV-Vis) spectrometer. The experimental results reveal that the film thickness, deposition pressure and the substrate temperature play significant role in the structural formation and the optical properties of the deposited ZnO thin films.

Left Atrial Sphericity Index Predicts Early Recurrence of Atrial Fibrillation After Direct-Current Cardioversion

DEFF Research Database (Denmark)

Osmanagic, Armin; Möller, Sören; Osmanagic, Azra

2016-01-01

BACKGROUND: Attempts to achieve rhythm control using direct-current cardioversion (DCC) are common in those with persistent atrial fibrillation (AF). Although often successful, AF recurs within 1 month in as many as 57% of patients. The aim of this study was to assess whether a baseline left atri...

Spreading depolarizations have prolonged direct current shifts and are associated with poor outcome in brain trauma

DEFF Research Database (Denmark)

Hartings, Jed A; Watanabe, Tomas; Bullock, M Ross

2011-01-01

, although prolonged events have not been observed in animal models. To determine whether detrimental penumbral-type depolarizations occur in human brain trauma, we analysed electrocorticographic recordings obtained by subdural electrode-strip monitoring during intensive care. Of 53 patients studied, 10......Cortical spreading depolarizations occur spontaneously after ischaemic, haemorrhagic and traumatic brain injury. Their effects vary spatially and temporally as graded phenomena, from infarction to complete recovery, and are reflected in the duration of depolarization measured by the negative direct...... current shift of electrocorticographic recordings. In the focal ischaemic penumbra, peri-infarct depolarizations have prolonged direct current shifts and cause progressive recruitment of the penumbra into the core infarct. In traumatic brain injury, the effects of spreading depolarizations are unknown...

Transcranial direct current stimulation transiently increases the blood-brain barrier solute permeability in vivo

Science.gov (United States)

Shin, Da Wi; Khadka, Niranjan; Fan, Jie; Bikson, Marom; Fu, Bingmei M.

2016-03-01

Transcranial Direct Current Stimulation (tDCS) is a non-invasive electrical stimulation technique investigated for a broad range of medical and performance indications. Whereas prior studies have focused exclusively on direct neuron polarization, our hypothesis is that tDCS directly modulates endothelial cells leading to transient changes in blood-brain-barrier (BBB) permeability (P) that are highly meaningful for neuronal activity. For this, we developed state-of-the-art imaging and animal models to quantify P to various sized solutes after tDCS treatment. tDCS was administered using a constant current stimulator to deliver a 1mA current to the right frontal cortex of rat (approximately 2 mm posterior to bregma and 2 mm right to sagittal suture) to obtain similar physiological outcome as that in the human tDCS application studies. Sodium fluorescein (MW=376), or FITC-dextrans (20K and 70K), in 1% BSA mammalian Ringer was injected into the rat (SD, 250-300g) cerebral circulation via the ipsilateral carotid artery by a syringe pump at a constant rate of ~3 ml/min. To determine P, multiphoton microscopy with 800-850 nm wavelength laser was applied to take the images from the region of interest (ROI) with proper microvessels, which are 100-200 micron below the pia mater. It shows that the relative increase in P is about 8-fold for small solute, sodium fluorescein, ~35-fold for both intermediate sized (Dex-20k) and large (Dex-70k) solutes, 10 min after 20 min tDCS pretreatment. All of the increased permeability returns to the control after 20 min post treatment. The results confirmed our hypothesis.

Surface modification of polyacrylonitrile co-polymer membranes using pulsed direct current nitrogen plasma

Energy Technology Data Exchange (ETDEWEB)

Pal, Dipankar; Neogi, Sudarsan; De, Sirshendu, E-mail: sde@che.iitkgp.ernet.in

2015-12-31

Low temperature plasma treatment using pulsed direct current discharge of nitrogen gas was employed to enhance hydrophilicity of the polyacrylonitrile co-polymer membranes. The membranes were characterized in terms of morphology, structure, hydrophilicity, and membrane performance. Properties and functional groups on the surface of polyacrylonitrile co-polymer membranes were investigated by contact angle, scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopy. Effects of plasma conditions, namely, pulsed voltage, duty cycle and treatment time on increase in membrane hydrophilicity were studied. Permeability of treated membrane was increased by 47% and it was retained up to 70 days. Surface etching due to plasma treatment was confirmed by weight loss of the treated membranes. Due to surface etching, average pore size increased and rejection of 200 kDa polyethylene glycol decreased to about 70% for the treated membrane. Oxygen and nitrogen functional groups were responsible for surface hydrophilicity. - Highlights: • Surface modification of polyacrylonitrile co-polymer membranes by pulsed direct current nitrogen plasma • Hydrophilic functional groups incorporated on the membrane surface • Significant enhancement of the permeability and wettability of the membranes • Water contact angle increased with storage time and finally stabilized.

Surface modification of polyacrylonitrile co-polymer membranes using pulsed direct current nitrogen plasma

International Nuclear Information System (INIS)

Pal, Dipankar; Neogi, Sudarsan; De, Sirshendu

2015-01-01

Low temperature plasma treatment using pulsed direct current discharge of nitrogen gas was employed to enhance hydrophilicity of the polyacrylonitrile co-polymer membranes. The membranes were characterized in terms of morphology, structure, hydrophilicity, and membrane performance. Properties and functional groups on the surface of polyacrylonitrile co-polymer membranes were investigated by contact angle, scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopy. Effects of plasma conditions, namely, pulsed voltage, duty cycle and treatment time on increase in membrane hydrophilicity were studied. Permeability of treated membrane was increased by 47% and it was retained up to 70 days. Surface etching due to plasma treatment was confirmed by weight loss of the treated membranes. Due to surface etching, average pore size increased and rejection of 200 kDa polyethylene glycol decreased to about 70% for the treated membrane. Oxygen and nitrogen functional groups were responsible for surface hydrophilicity. - Highlights: • Surface modification of polyacrylonitrile co-polymer membranes by pulsed direct current nitrogen plasma • Hydrophilic functional groups incorporated on the membrane surface • Significant enhancement of the permeability and wettability of the membranes • Water contact angle increased with storage time and finally stabilized.

Load Torque Compensator for Model Predictive Direct Current Control in High Power PMSM Drive Systems

DEFF Research Database (Denmark)

Preindl, Matthias; Schaltz, Erik

2010-01-01

In drive systems the most used control structure is the cascade control with an inner torque, i.e. current and an outer speed control loop. The fairly small converter switching frequency in high power applications, e.g. wind turbines lead to modest speed control performance. An improvement bring...... the use of a current controller which takes into account the discrete states of the inverter, e.g. DTC or a more modern approach: Model Predictive Direct Current Control (MPDCC). Moreover overshoots and oscillations in the speed are not desired in many applications, since they lead to mechanical stress...

Methods for Specific Electrode Resistance Measurement during Transcranial Direct Current Stimulation

Science.gov (United States)

Khadka, Niranjan; Rahman, Asif; Sarantos, Chris; Truong, Dennis Q.; Bikson, Marom

2014-01-01

Background Transcranial Direct Current Stimulation (tDCS) is investigated to treat a wide range of neuropsychiatric disorders, for rehabilitation, and for enhancing cognitive performance. The monitoring of electrode resistance before and during tDCS is considered important for tolerability and safety, where an unusually high resistance is indicative of undesired electrode or poor skin contact conditions. Conventional resistance measurement methods do not isolate individual electrode resistance but rather measures overall voltage. Moreover, for HD-tDCS devices, cross talk across electrodes makes concurrent resistance monitoring unreliable. Objective We propose a novel method for monitoring of the individual electrode resistance during tDCS, using a super-position of direct current with a test-signal (low-intensity and low-frequency sinusoids with electrode– specific frequencies) and a single sentinel electrode (not used for DC). Methods To validate this methodology, we developed lumped-parameter models of two and multi-electrode tDCS. Approaches with and without a sentinel electrode were solved and underlying assumptions identified. Assumptions were tested and parameterized in healthy participants using forearm stimulation combining tDCS (2 mA) and sinusoidal test-signals (38 μA and 76 μA peak to peak at 1 Hz, 10 Hz, and 100 Hz) and an in vitro test (where varied electrode failure modes were created). DC and AC component voltages across the electrodes were compared and participants were asked to rate subjective pain. Results A sentinel electrode is required to isolate electrode resistance in a two-electrode tDCS system. For multi-electrode resistance tracking, cross talk was aggravated with electrode proximity and current/resistance mismatches, but could be corrected using proposed approaches. Average voltage and average pain scores were not significantly different across test current intensities and frequencies (two-way repeated measures ANOVA) indicating the

Inter- and Intra-individual Variability in Response to Transcranial Direct Current Stimulation (tDCS) at Varying Current Intensities.

Science.gov (United States)

Chew, Taariq; Ho, Kerrie-Anne; Loo, Colleen K

2015-01-01

Translation of transcranial direct current stimulation (tDCS) from research to clinical practice is hindered by a lack of consensus on optimal stimulation parameters, significant inter-individual variability in response, and in sufficient intra-individual reliability data. Inter-individual differences in response to anodal tDCS at a range of current intensities were explored. Intra-individual reliability in response to anodal tDCS across two identical sessions was also investigated. Twenty-nine subjects participated in a crossover study. Anodal-tDCS using four different current intensities (0.2, 0.5, 1 and 2 mA), with an anode size of 16 cm2, was tested. The 0.5 mA condition was repeated to assess intra-individual variability. TMS was used to elicit 40 motor-evoked potentials (MEPs) before 10 min of tDCS, and 20 MEPs at four time-points over 30 min following tDCS. ANOVA revealed no main effect of TIME for all conditions except the first 0.5 mA condition, and no differences in response between the four current intensities. Cluster analysis identified two clusters for the 0.2 and 2 mA conditions only. Frequency distributions based on individual subject responses (excitatory, inhibitory or no response) to each condition indicate possible differential responses between individuals to different current intensities. Test-retest reliability was negligible (ICC(2,1) = -0.50). Significant inter-individual variability in response to tDCS across a range of current intensities was found. 2 mA and 0.2 mA tDCS were most effective at inducing a distinct response. Significant intra-individual variability in response to tDCS was also found. This has implications for interpreting results of single-session tDCS experiments. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

Can the use of pulsed direct current induce oscillation in the applied pressure during spark plasma sintering?

International Nuclear Information System (INIS)

Salamon, David; Eriksson, Mirva; Nygren, Mats; Shen Zhijian

2012-01-01

The spark plasma sintering (SPS) process is known for its rapid densification of metals and ceramics. The mechanism behind this rapid densification has been discussed during the last few decades and is yet uncertain. During our SPS experiments we noticed oscillations in the applied pressure, related to a change in electric current. In this study, we investigated the effect of pulsed electrical current on the applied mechanical pressure and related changes in temperature. We eliminated the effect of sample shrinkage in the SPS setup and used a transparent quartz die allowing direct observation of the sample. We found that the use of pulsed direct electric current in our apparatus induces pressure oscillations with the amplitude depending on the current density. While sintering Ti samples we observed temperature oscillations resulting from pressure oscillations, which we attribute to magnetic forces generated within the SPS apparatus. The described current–pressure–temperature relations might increase understanding of the SPS process.

Alternatives for blocking direct current in AC system neutrals at the Radisson/LG2 complex

International Nuclear Information System (INIS)

Eitzmann, M.A.; Walling, R.A.; Sublich, M.; Kah, A.; Huynh, H.; Granger, M.; Dutil, A.

1992-01-01

Severe offset saturation results from the passage of direct current through power transformers. Such direct current can arise from geomagnetic disturbances, or resistive coupling of the substation ground to HVDC earth electrodes. This paper documents the development of alternative approaches for the design and application of blocking devices placed between transformer neutrals and the substation ground. System constraints on the impedance and overvoltage limitation of the neutral blocking device (NBD) are covered. Three alternative NBD schemes are developed and optimized. System performance of the NBD is discussed, as are the practical implementation considerations for this unconventional equipment application. Although the paper focuses on the NBD requirements of Hydro-Quebec's Radisson/LG2 complex, the fundamental information is applicable to any situation where dc must be clocked from a power transformer neutral in a system designed for effectively-grounded operation

MCNP6 simulation of radiographs generated from megaelectron volt X-rays for characterizing a computed tomography system

Science.gov (United States)

Dooraghi, Alex A.; Tringe, Joseph W.

2018-04-01

To evaluate conventional munition, we simulated an x-ray computed tomography (CT) system for generating radiographs from nominal x-ray energies of 6 or 9 megaelectron volts (MeV). CT simulations, informed by measured data, allow for optimization of both system design and acquisition techniques necessary to enhance image quality. MCNP6 radiographic simulation tools were used to model ideal detector responses (DR) that assume either (1) a detector response proportional to photon flux (N) or (2) a detector response proportional to energy flux (E). As scatter may become significant with MeV x-ray systems, simulations were performed with and without the inclusion of object scatter. Simulations were compared against measurements of a cylindrical munition component principally composed of HMX, tungsten and aluminum encased in carbon fiber. Simulations and measurements used a 6 MeV peak energy x-ray spectrum filtered with 3.175 mm of tantalum. A detector response proportional to energy which includes object scatter agrees to within 0.6 % of the measured line integral of the linear attenuation coefficient. Exclusion of scatter increases the difference between measurement and simulation to 5 %. A detector response proportional to photon flux agrees to within 20 % when object scatter is included in the simulation and 27 % when object scatter is excluded.

Pediatric neurology training in Canada: current status and future directions.

Science.gov (United States)

Doja, Asif

2012-05-01

Child neurology training in Canada has changed considerably over time, with increasing requirements for standardized teaching of the fundamentals of child neurology and the CanMEDS competencies. We sought to determine the current status of child neurology training in Canada as well future directions for training. A web-based survey was sent to program directors (PD's) of active pediatric neurology training programs. General questions about the programs were asked, as well as about success at the Royal College of Physicians and Surgeons of Canada (RCPSC) exam, breakdown of rotations, views on CanMEDS roles and questions on the future of pediatric neurology. 9/9 PD's completed the survey. 96.5% of all trainees successfully passed their RCPSC exam from 2001-2006. Breakdowns of the number and type of rotations for each year of training were provided. All CanMEDS roles were deemed to be important by PD's and programs have developed unique strategies to teach and assess these roles.92.6% of trainees chose to go into academic practice, with the most popular subspecialty being epilepsy. All PD's favour joint training sessions particularly for neurogenetics and neuromuscular disease. Overall, PD's suggest recruitment for future child neurologists at the medical student level but are divided as to whether we are currently training too few or too many child neurologists. This survey provides a view of the current state of pediatric neurology training in Canada and suggestions for further development of post-graduate training. In particular, attention should be given to joint educational programs as well as urgently assessing the manpower needs of child neurologists.

Grading of direct laryngoscopy. A survey of current practice.

Science.gov (United States)

Cohen, A M; Fleming, B G; Wace, J R

1994-06-01

One hundred and twenty anaesthetists (30 of each grade), from three separate regions, were interviewed as to how they recorded the appearance of laryngeal structures at direct laryngoscopy and about their knowledge of the commonly used numerical grading system. About two-thirds of anaesthetists surveyed (69.2%) used the numerical grading system, but of these, over half could not identify a 'grade 2' laryngoscopic appearance correctly. Of anaesthetists who did not use the numerical method, over half could not correctly state the difference between a 'grade 2' and a 'grade 3' laryngoscopic appearance. Over 40% of anaesthetists stated incorrectly that the grading should be made on the initial view, even when laryngeal pressure had been needed. Junior anaesthetists were more likely to use the numerical method of recording. The results show that there is unacceptable uncertainty and inaccuracy in the use of the numerical grading system by users as well as non-users, which makes the current routine clinical use of the numerical grading system unsatisfactory.

Current direction and CTD data from moored current meter and CTD casts in the North Pacific Ocean from 1979-02-05 to 1980-12-01 (NODC Accession 8300042)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction and CTD data were collected using moored current meter and CTD casts in the North Pacific Ocean from February 5, 1979 to December 1, 1980. Data...

Direct current induced short-term modulation of the left dorsolateral prefrontal cortex while learning auditory presented nouns

Directory of Open Access Journals (Sweden)

Meyer Martin

2009-07-01

Full Text Available Abstract Background Little is known about the contribution of transcranial direct current stimulation (tDCS to the exploration of memory functions. The aim of the present study was to examine the behavioural effects of right or left-hemisphere frontal direct current delivery while committing to memory auditory presented nouns on short-term learning and subsequent long-term retrieval. Methods Twenty subjects, divided into two groups, performed an episodic verbal memory task during anodal, cathodal and sham current application on the right or left dorsolateral prefrontal cortex (DLPFC. Results Our results imply that only cathodal tDCS elicits behavioural effects on verbal memory performance. In particular, left-sided application of cathodal tDCS impaired short-term verbal learning when compared to the baseline. We did not observe tDCS effects on long-term retrieval. Conclusion Our results imply that the left DLPFC is a crucial area involved in short-term verbal learning mechanisms. However, we found further support that direct current delivery with an intensity of 1.5 mA to the DLPFC during short-term learning does not disrupt longer lasting consolidation processes that are mainly known to be related to mesial temporal lobe areas. In the present study, we have shown that the tDCS technique has the potential to modulate short-term verbal learning mechanism.

Counteracting Fatigue in Multiple Sclerosis with Right Parietal Anodal Transcranial Direct Current Stimulation

OpenAIRE

Hanken, Katrin; Bosse, Mona; M?hrke, Kim; Eling, Paul; Kastrup, Andreas; Antal, Andrea; Hildebrandt, Helmut

2016-01-01

BACKGROUND: Fatigue in multiple sclerosis (MS) patients appears to correlate with vigilance decrement as reflected in an increase in reaction time (RT) and errors with prolonged time-on-task. OBJECTIVES: The aim of this study was to investigate whether anodal transcranial direct current stimulation (tDCS) over the right parietal or frontal cortex counteracts fatigue-associated vigilance decrement and subjective fatigue. METHODS: In study I, a randomized double-blind placebo-controll...

Detrapping of tungsten nanoparticles in a direct-current argon glow discharge

Energy Technology Data Exchange (ETDEWEB)

Couëdel, L., E-mail: lenaic.couedel@univ-amu.fr; Kumar, K. Kishor; Arnas, C. [Laboratoire de Physique des Interactions Ioniques et Moléculaires, CNRS, Aix-Marseille Université, 13397 Marseille (France)

2014-12-15

Nanoparticles are grown from the sputtering of a tungsten cathode in a direct current argon glow discharge. Laser light scattering of a vertical laser sheet going through the plasma reveals that the dust particle cloud is compressed and pushed towards the anode during the discharge. Scanning electron microscopy images of substrates exposed to the plasma for given durations show that dust particles are continuously falling down on the anode during the discharge. These observations are explained by the fact that the electrostatic force at the negative glow-anode sheath boundary cannot balance the ion drag, gravity, and thermophoresis forces for particles of more than a few tens of nanometres in diameter.

Modulation of Brain Activity with Noninvasive Transcranial Direct Current Stimulation (tDCS): Clinical Applications and Safety Concerns

Science.gov (United States)

Zhao, Haichao; Qiao, Lei; Fan, Dongqiong; Zhang, Shuyue; Turel, Ofir; Li, Yonghui; Li, Jun; Xue, Gui; Chen, Antao; He, Qinghua

2017-01-01

Transcranial direct current stimulation (tDCS) is a widely-used tool to induce neuroplasticity and modulate cortical function by applying weak direct current over the scalp. In this review, we first introduce the underlying mechanism of action, the brief history from discovery to clinical scientific research, electrode positioning and montages, and parameter setup of tDCS. Then, we review tDCS application in clinical samples including people with drug addiction, major depression disorder, Alzheimer's disease, as well as in children. This review covers the typical characteristics and the underlying neural mechanisms of tDCS treatment in such studies. This is followed by a discussion of safety, especially when the current intensity is increased or the stimulation duration is prolonged. Given such concerns, we provide detailed suggestions regarding safety procedures for tDCS operation. Lastly, future research directions are discussed. They include foci on the development of multi-tech combination with tDCS such as with TMS and fMRI; long-term behavioral and morphological changes; possible applications in other research domains, and more animal research to deepen the understanding of the biological and physiological mechanisms of tDCS stimulation. PMID:28539894

Investigation of students’ intermediate conceptual understanding levels: the case of direct current electricity concepts

International Nuclear Information System (INIS)

Aktan, D Cobanoglu

2013-01-01

Conceptual understanding is one of the main topics in science and physics education research. In the majority of conceptual understanding studies, students’ understanding levels were categorized dichotomously, either as alternative or scientific understanding. Although they are invaluable in many ways, namely developing new instructional materials and assessment instruments, students’ alternative understandings alone are not sufficient to describe students’ conceptual understanding in detail. This paper introduces an example of a study in which a method was developed to assess and describe students’ conceptual understanding beyond alternative and scientific understanding levels. In this study, six undergraduate students’ conceptual understanding levels of direct current electricity concepts were assessed and described in detail by using their answers to qualitative problems. In order to do this, conceptual understanding indicators are described based on science and mathematics education literature. The students’ understanding levels were analysed by assertion analysis based on the conceptual understanding indicators. The results indicated that the participants demonstrated three intermediate understanding levels in addition to alternative and scientific understanding. This paper presents the method and its application to direct current electricity concepts. (paper)

Direct current electrotherapy for internal haemorrhoids: experience in a tertiary health institution

Science.gov (United States)

Olatoke, Samuel; Adeoti, Moses; Agodirin, Olayide; Ajape, Abdulwahab; Agbola, John

2014-01-01

Introduction Haemorrhoids disease is one of the most frequently occurring disabling conditions of the anorectum. We re-present the method, advantages and results of using direct current electrotherapy in the treatment of haemorrhoids. Methods Symptomatic grades 1, 2 or 3 internal and mixed haemorroids were treated. Exposure and evaluation was with an operative proctoscope which visualized one-eighth of the anal canal at a time. All diseased segments were treated per visit, indicators of successful treatment were, darkening of the treated segment, immediate shrinking of the haemorrhoid and ceasation of popping sound of gas release at the probe tip. Patients were followed up for two weeks. No bowel preparations, medications, anesthesia nor admission was required. Results Four hundred and fifty six segments were exposed, 252(55.3%) were diseased. eight patients with either grades 2 or 3 diseases required two treatment visits. The most common symptom was rectal bleeding (94.7%), followed by prolapsed but manually reduced hemorrhoids (68%). Prolapse of tuft of haemorrhoidal tissue with spontaneous return was seen in 59.6%, anal pain in 29.8%, and itching in 3.5%. the median number treated segments per patient was 4. No complication was encountered. All patients treated remained symptom free at a mean duration of follow up of 16 months. Conclusion Direct current electrotherapy is an effective, painless and safe out-patient treatment method for grades 1 to 3 internal and mixed hemorrhoid disease. PMID:25419283

Characterization of manganese dioxide electrodeposited by pulse and direct current for electrochemical capacitor

International Nuclear Information System (INIS)

Adelkhani, H.; Ghaemi, M.

2010-01-01

This paper describes the electrochemical capacitor behavior of manganese dioxide (MD, MnO 2 ) samples that were prepared by direct current (DCMD) and pulse current (PCMD) electrodeposition. The capacitive characteristics of the samples were studied in 0.5 M aqueous Na 2 SO 4 solution using the cyclic voltammetry (CV) method. Scanning electron microscopy (SEM), X-ray diffraction (XRD), chemical composition analyses and the Barrett-Joyner-Halenda (BJH) method were employed to characterize the samples. In the study of the effect of scan rate on capacitance, it was revealed that PCMD displayed higher capacities than DCMD for all scan rates. The higher capacitive performance of PCMD was attributed to its porosity (specific surface area, pore volume, and pore-size distribution), chemical composition and structural properties.

Direct current linear measurement sub-assembly data and test methods. Nuclear electronic equipment for control and monitoring panel

International Nuclear Information System (INIS)

1977-12-01

The M.C.H./M.E.N.T.3 document is concerned with sub-assemblies intended for measuring on a linear scale the neutron fluence rate or radiation dose rate when connected with nuclear detectors working in current. The symbols used are described. Some definitions and a bibliography are given. The main characteristics of direct current linear measurement sub-assemblies are then described together with corresponding test methods. This type of instrument indicates on a linear scale the level of a direct current applied to its input. The document reviews linear sub-assemblies for general purpose applications, difference amplifiers for monitoring, and averaging amplifiers. The document is intended for electronics manufacturers, designers, persons participating in acceptance trials and plant operators [fr

Counteracting fatigue in multiple sclerosis with right parietal anodal transcranial direct current stimulation

OpenAIRE

Katrin Hanken; Katrin Hanken; Mona Bosse; Kim Möhrke; Paul Eling; Andreas Kastrup; Andrea Antal; Helmut Hildebrandt; Helmut Hildebrandt

2016-01-01

Background: Fatigue in multiple sclerosis (MS) patients appears to correlate with vigilance decrement as reflected in an increase in reaction time and errors with prolonged time-on-task. Objectives: The aim of this study was to investigate whether anodal transcranial direct current stimulation (tDCS) over the right parietal or frontal cortex counteracts fatigue-associated vigilance decrement and subjective fatigue. Methods: In study I, a randomized double-blind placebo-controlled study, anoda...

Dependence of CIT [Compact Ignition Tokamak] PF [poloidal field] coil currents on profile and shape parameters using the Control Matrix

International Nuclear Information System (INIS)

Strickler, D.J.; Peng, Y-K.M.; Jardin, S.C.; Pomphrey, N.

1990-01-01

The plasma shaping flexibility of the Compact Ignition Tokamak (CIT) poloidal field (PF) coil set is demonstrated through MHD equilibrium calculations of optimal PF coil current distributions and their variation with poloidal beta, internal inductance, plasma 95% elongation, and 95% triangularity. Calculations of the magnetic stored energy are used to compare solutions associated with various plasma parameters. The Control Matrix (CM) equilibrium code, together with the nonlinear equation and numerical optimization software packages HYBRD, and VMCON, respectively, are used to find equilibrium coil current distributions for fixed divertor geometry, volt-seconds, and plasma profiles in order to isolate the dependence on individual parameters. A reference equilibrium and coil current distribution are chosen, and correction currents dI are determined using the CM equilibrium method to obtain other specified plasma shapes. The reference equilibrium is the κ = 2 divertor at beginning of flattop (BOFT) with a minimum stored energy solution for the coil current distribution. The pressure profile function is fixed

A new circuit technique for reduced leakage current in Deep Submicron CMOS technologies

Directory of Open Access Journals (Sweden)

A. Schmitz

2005-01-01

Full Text Available Modern CMOS processes in the Deep Submicron regime are restricted to supply voltages below 2 volts and further to account for the transistors' field strength limitations and to reduce the power per logic gate. To maintain the high switching performance, the threshold voltage must be scaled according with the supply voltage. However, this leads to an increased subthreshold current of the transistors in standby mode (VGS=0. Another source of leakage is gate current, which becomes significant for gate oxides of 3nm and below. We propose a Self-Biasing Virtual Rails (SBVR - CMOS technique which acts like an adaptive local supply voltage in case of standby mode. Most important sources of leakage currents are reduced by this technique. Moreover, SBVR-CMOS is capable of conserving stored information in sleep mode, which is vital for memory circuits. Memories are exposed to radiation causing soft errors. This well-known problem becomes even worse in standby mode of typical SRAMs, that have low driving performance to withstand alpha particle hits. In this paper, a 16-transistor SRAM cell is proposed, which combines the advantage of extremely low leakage currents with a very high soft error stability.

Physical principles of artificial stimulation of the heart : Stimulation of the canine heart in situ

NARCIS (Netherlands)

Schneider, H.

1. 1. In artificial heart stimulation, the essential quantity is the density of current, , in the intramyocardial wall. Dosage of the pulse amplitude in volts can have serious consequences for the patient. Curve indications in volts on pacemakers and in publications and records must, therefore, be

First direct observations linking confined supercritical turbidity currents to their depositional architecture and facies characteristics

Science.gov (United States)

Hage, S.; Cartigny, M.; Hughes Clarke, J. E.; Clare, M. A.; Sumner, E.; Hubbard, S. M.; Talling, P.; Lintern, G.; Stacey, C.; Vardy, M. E.; Hunt, J.; Vendettuoli, D.; Yokokawa, M.; Hizzett, J. L.; Vellinga, A. J.; Azpiroz, M.

2017-12-01

Turbidity currents transfer globally significant amounts of sediment via submarine channels from the continental margin to deep submarine fans. Submarine channel inception is thought to result from erosive, supercritical turbidity currents that are common in proximal settings of the marine realm. Recent monitoring of submarine processes have provided the first measurements of supercritical turbidity currents (Hughes Clarke, 2016), demonstrating that they drive the upstream migration of crescentic bedforms in confined submarine channels. Although upstream-migrating bedforms are common in confined channels across the world's oceans, there is considerable debate over the type of deposits that they produce. It is important to understand what types of deposit record these supercritical bedforms to potentially identify them from geological archives. For the first time, we combine direct measurements from supercritical field-scale turbidity currents with the facies and depositional architecture resulting from such flows. We show how the subsurface architecture evolves in a highly active channel at Squamish submarine delta, British Columbia, Canada. Repeated upstream migration of bedforms is found to create two main deposit geometries. First, regular back-stepping beds result from flow deceleration on the slightly-inclined sides of the bedforms. Second, lens-shaped scour fills composed of massive deposits result from erosion of the back-stepping beds by subsequent turbidity currents. We relate our findings to a range of ancient outcrop studies to demonstrate that supercritical flows are common in proximal settings through the geological record. This study provides the first direct observation-based model to identify confined supercritical turbidity currents and their associated upslope-migrating bedforms in the sedimentary record. This is important for correctly identifying the proximal sites of ancient submarine channels that served as past conduits for globally

On the structure of intermediate state created by the direct current

International Nuclear Information System (INIS)

Kan, Ya.S.; Frolov, V.A.

1974-01-01

Observations were made of the structure of an intermediate state formed at the destruction of superconductivity of a cylindrical tin sample by an electric current through it. For this purpose, there was determined the nature of the dependence of the magnetic permeability averaged over a section normal with the sample axis on the position of this section relative to the axis. the quantity actually measured was the inductance of a short (0.5 mm) superconductive probe coil embracing the sample and moving along the axis of the latter. In order the inductance were representatative of the magnetic permeability in the depth of a thick (5 mm in diameter) sample, measurements were made with a direct current by means of the device specially designed for this purpose; the operating principle and method for checking of this device being briefly described in the paper. The curves of oscillations of the inductance of the probe with the latter being moved along the sample suggested a conclusion that the structure of the intermediate state had a periodic nature (of the London type) with a period of 1.3 mm. The reduction of the oscillation amplitude and the increase of their average level while an increase of the current passing through the sample above the critical value (at constant temperature) indicated the reduction of the diameter of the core, being in the intermediate state, and an increase of the thickness of a normal layer. Measurements were made at temperatures (13-17)x10 -3 deg K below Tsub(k) with a current of 2-3 A in the sample

Enhanced motor learning following task-concurrent dual transcranial direct current stimulation.

Directory of Open Access Journals (Sweden)

Sophia Karok

Full Text Available OBJECTIVE: Transcranial direct current stimulation (tDCS of the primary motor cortex (M1 has beneficial effects on motor performance and motor learning in healthy subjects and is emerging as a promising tool for motor neurorehabilitation. Applying tDCS concurrently with a motor task has recently been found to be more effective than applying stimulation before the motor task. This study extends this finding to examine whether such task-concurrent stimulation further enhances motor learning on a dual M1 montage. METHOD: Twenty healthy, right-handed subjects received anodal tDCS to the right M1, dual tDCS (anodal current over right M1 and cathodal over left M1 and sham tDCS in a repeated-measures design. Stimulation was applied for 10 mins at 1.5 mA during an explicit motor learning task. Response times (RT and accuracy were measured at baseline, during, directly after and 15 mins after stimulation. Motor cortical excitability was recorded from both hemispheres before and after stimulation using single-pulse transcranial magnetic stimulation. RESULTS: Task-concurrent stimulation with a dual M1 montage significantly reduced RTs by 23% as early as with the onset of stimulation (p<0.01 with this effect increasing to 30% at the final measurement. Polarity-specific changes in cortical excitability were observed with MEPs significantly reduced by 12% in the left M1 and increased by 69% in the right M1. CONCLUSION: Performance improvement occurred earliest in the dual M1 condition with a stable and lasting effect. Unilateral anodal stimulation resulted only in trendwise improvement when compared to sham. Therefore, task-concurrent dual M1 stimulation is most suited for obtaining the desired neuromodulatory effects of tDCS in explicit motor learning.

Influence of Concurrent Finger Movements on Transcranial Direct Current Stimulation (tDCS)-Induced Aftereffects.

Science.gov (United States)

Shirota, Yuichiro; Terney, Daniella; Antal, Andrea; Paulus, Walter

2017-01-01

Transcranial direct current stimulation (tDCS) has been reported to have bidirectional influence on the amplitude of motor-evoked potentials (MEPs) in resting participants in a polarity-specific manner: anodal tDCS increased and cathodal tDCS decreased them. More recently, the effects of tDCS have been shown to depend on a number of additional factors. We investigated whether a small variety of movements involving target and non-target muscles could differentially modify the efficacy of tDCS. MEPs were elicited from the right first dorsal interosseous muscle, defined as the target muscle, by single pulse transcranial magnetic stimulation (TMS) over the primary motor cortex (M1). During M1 tDCS, which lasted for 10 min applying anodal, cathodal, or sham condition, the participants were instructed to squeeze a ball with their right hand (Task 1), to move their right index finger only in the medial (Task 2), in the lateral direction (Task 3), or in medial and lateral direction alternatively (Task 4). Anodal tDCS reduced MEP amplitudes measured in Task 1 and Task 2, but to a lesser extent in the latter. In Task 3, anodal tDCS led to greater MEP amplitudes than cathodal stimulation. Alternating movements resulted in no effect of tDCS on MEP amplitude (Task 4). The results are congruent with the current notion that the aftereffects of tDCS are highly variable relying on a number of factors including the type of movements executed during stimulation.

Current approaches and future directions in the treatment of leprosy

Directory of Open Access Journals (Sweden)

Worobec SM

2012-08-01

Full Text Available Sophie M WorobecDepartment of Dermatology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, USAAbstract: This review surveys current treatments and future treatment trends in leprosy from a clinical perspective. The World Health Organization provides a multidrug treatment regimen that targets the Mycobacterium leprae bacillus which causes leprosy. Several investigational drugs are available for the treatment of drug-resistant M. leprae. Future directions in leprosy treatment will focus on: the molecular signaling mechanism M. leprae uses to avoid triggering an immune response; prospective studies of the side effects experienced during multiple-drug therapy; recognition of relapse rates post-completion of designated treatments; combating multidrug resistance; vaccine development; development of new diagnostic tests; and the implications of the recent discovery of a genetically distinct leprosy-causing bacillus, Mycobacterium lepromatosis.Keywords: epidemiology, leprosy, Hansen’s disease, multidrug resistance, multidrug therapy

Direct current magnetron sputtering deposition of InN thin films

International Nuclear Information System (INIS)

Cai Xingmin; Hao Yanqing; Zhang Dongping; Fan Ping

2009-01-01

In this paper, InN thin films were deposited on Si (1 0 0) and K9 glass by reactive direct current magnetron sputtering. The target was In metal with the purity of 99.999% and the gases were Ar (99.999%) and N 2 (99.999%). The properties of InN thin films were studied. Scanning electron microscopy (SEM) shows that the film surface is very rough and energy dispersive X-ray spectroscopy (EDX) shows that the film contains In, N and very little O. X-ray diffraction (XRD) and Raman scattering reveal that the film mainly contains hexagonal InN. The four-probe measurement shows that InN film is conductive. The transmission measurement demonstrates that the transmission of InN deposited on K9 glass is as low as 0.5% from 400 nm to 800 nm.

Automatic adjustment of bias current for direct current superconducting quantum interference device

International Nuclear Information System (INIS)

Makie-Fukuda, K.; Hotta, M.; Okajima, K.; Kado, H.

1993-01-01

A new method of adjusting the bias current of dc superconducting quantum interference device (SQUID) is described. It is shown that the signal-to-noise ratio of a SQUID magnetometer connected in a flux-locked loop configuration is proportional to the second harmonic of the output signal from the SQUID. A circuit configuration that can automatically optimize a SQUID's bias current by measuring this second harmonic and adjusting the bias current accordingly is proposed

Current Directions in Mediation Analysis

Science.gov (United States)

MacKinnon, David P.; Fairchild, Amanda J.

2010-01-01

Mediating variables continue to play an important role in psychological theory and research. A mediating variable transmits the effect of an antecedent variable on to a dependent variable, thereby providing more detailed understanding of relations among variables. Methods to assess mediation have been an active area of research for the last two decades. This paper describes the current state of methods to investigate mediating variables. PMID:20157637

Current Directions in Mediation Analysis

OpenAIRE

MacKinnon, David P.; Fairchild, Amanda J.

2009-01-01

Mediating variables continue to play an important role in psychological theory and research. A mediating variable transmits the effect of an antecedent variable on to a dependent variable, thereby providing more detailed understanding of relations among variables. Methods to assess mediation have been an active area of research for the last two decades. This paper describes the current state of methods to investigate mediating variables.

Effectiveness of anodal transcranial direct current stimulation in patients with chronic low back pain: Design, method and protocol for a randomised controlled trial

Directory of Open Access Journals (Sweden)

Luedtke Kerstin

2011-12-01

Full Text Available Abstract Background Electrical stimulation of central nervous system areas with surgically implanted stimulators has been shown to result in pain relief. To avoid the risks and side effects of surgery, transcranial direct current stimulation is an option to electrically stimulate the motor cortex through the skull. Previous research has shown that transcranial direct current stimulation relieves pain in patients with fibromyalgia, chronic neuropathic pain and chronic pelvic pain. Evidence indicates that the method is pain free, safe and inexpensive. Methods/Design A randomised controlled trial has been designed to evaluate the effect of transcranial direct current stimulation over the motor cortex for pain reduction in patients with chronic low back pain. It will also investigate whether transcranial direct current stimulation as a prior treatment enhances the symptom reduction achieved by a cognitive-behavioural group intervention. Participants will be randomised to receive a series of 5 days of transcranial direct current stimulation (2 mA, 20 mins or 20 mins of sham stimulation; followed by a cognitive-behavioural group programme. The primary outcome parameters will measure pain (Visual Analog Scale and disability (Oswestry Disability Index. Secondary outcome parameters will include the Fear Avoidance Beliefs Questionnaire, the Funktionsfragebogen Hannover (perceived function, Hospital Anxiety Depression Scale, bothersomeness and Health Related Quality of Life (SF 36, as well as Patient-Perceived Satisfactory Improvement. Assessments will take place immediately prior to the first application of transcranial direct current stimulation or sham, after 5 consecutive days of stimulation, immediately after the cognitive-behavioural group programme and at 4 weeks, 12 weeks and 24 weeks follow-up. Discussion This trial will help to determine, whether transcranial direct current stimulation is an effective treatment for patients with chronic low back

The Effectiveness of Transcranial Direct Current Stimulation (tDCS on Working Memory in Patients with Major Depression

Directory of Open Access Journals (Sweden)

Mahboube Ebadi

2017-08-01

Full Text Available Abstract Background: The aim of this study was to evaluate the effectiveness of of transcranial direct current stimulation (tDCS on working memory in patients with major depression. Materials and Methods: The research method was quasi-experimental with pretest and post-test and follow-up with control group. The research population comprised female outpatient referrals to private psychiatric centers and psychological counseling centers in Tehran in the first half of 2016, They had received a diagnosis of depression by a psychiatrist at least once. Of these, 30 females were selected as a sample group with convenience sampling method and based on the criteria of inclusion and exclusion and were divided randomly into two groups , experimental (n = 15 and control (n = 15 group. The experimental group received transcranial direct current stimulation (tDCS in 10 sessions, While this intervention was not provided to the control group. The data were collected by N-BACK. Analysis of variance with repeated measurments was used to test the research hypothesis. Results: The results showed that transcranial direct current stimulation (tDCS had a significant effect on increasing working memory and the impact will continue to follow up. Conclusion: Therefore, this approach can be used to improve working memory in people with major depression.

Direct-current substrate bias effects on amorphous silicon sputter-deposited films for thin film transistor fabrication

International Nuclear Information System (INIS)

Jun, Seung-Ik; Rack, Philip D.; McKnight, Timothy E.; Melechko, Anatoli V.; Simpson, Michael L.

2005-01-01

The effect that direct current (dc) substrate bias has on radio frequency-sputter-deposited amorphous silicon (a-Si) films has been investigated. The substrate bias produces a denser a-Si film with fewer defects compared to unbiased films. The reduced number of defects results in a higher resistivity because defect-mediated conduction paths are reduced. Thin film transistors (TFTs) that were completely sputter deposited were fabricated and characterized. The TFT with the biased a-Si film showed lower leakage (off-state) current, higher on/off current ratio, and higher transconductance (field effect mobility) than the TFT with the unbiased a-Si film

Development of an air-breathing direct methanol fuel cell with the cathode shutter current collectors

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yufeng; Liu, Xiaowei [Key Laboratory of Micro-Systems and Micro-Structures Manufacturing, Ministry of Education, Harbin 150001 (China); MEMS Center, Harbin Institute of Technology, Harbin 150001 (China); Zhang, Peng; Zhang, Bo; Li, Jianmin; Deng, Huichao [MEMS Center, Harbin Institute of Technology, Harbin 150001 (China)

2010-06-15

An air-breathing direct methanol fuel cell with a novel cathode shutter current collector is fabricated to develop the power sources for consumer electronic devices. Compared with the conventional circular cathode current collector, the shutter one improves the oxygen consumption and mass transport. The anode and cathode current collectors are made of stainless steel using thermal stamping die process. Moreover, an encapsulation method using the tailor-made clamps is designed to assemble the current collectors and MEA for distributing the stress of the edges and inside uniformly. It is observed that the maximum power density of the air-breathing DMFC operating with 1 M methanol solution achieves 19.7 mW/cm{sup 2} at room temperature. Based on the individual DMFCs, the air-breathing stack consisting of 36 DMFC units is achieved and applied to power a notebook computer. (author)

Is transcranial direct current stimulation a potential method for improving response inhibition?☆

OpenAIRE

Kwon, Yong Hyun; Kwon, Jung Won

2013-01-01

Inhibitory control of movement in motor learning requires the ability to suppress an inappropriate action, a skill needed to stop a planned or ongoing motor response in response to changes in a variety of environments. This study used a stop-signal task to determine whether transcranial direct-current stimulation over the pre-supplementary motor area alters the reaction time in motor inhibition. Forty healthy subjects were recruited for this study and were randomly assigned to either the tran...

Current status of direct dark matter detection experiments

Science.gov (United States)

Liu, Jianglai; Chen, Xun; Ji, Xiangdong

2017-03-01

Much like ordinary matter, dark matter might consist of elementary particles, and weakly interacting massive particles are one of the prime suspects. During the past decade, the sensitivity of experiments trying to directly detect them has improved by three to four orders of magnitude, but solid evidence for their existence is yet to come. We overview the recent progress in direct dark matter detection experiments and discuss future directions.

Adaptive Environmentally Contained Power and Cooling IT Infrastructure for the Data Center

Energy Technology Data Exchange (ETDEWEB)

Mann, Ron; Chavez, Miguel, E.

2012-06-27

The objectives of this program were to research and develop a fully enclosed Information Technology (IT) rack system for 100 kilowatts (KW) of IT load that provides its own internal power and cooling with High Voltage Alternating Current (HVAC defined as 480 volt) and chilled water as the primary inputs into the system and accepts alternative energy power sources such as wind and solar. For maximum efficiency, internal power to the IT equipment uses distributed High Voltage Direct Current power (HVDC defined as 360-380 volt) from the power source to the IT loads. The management scheme aggressively controls energy use to insure the best utilization of available power and cooling resources. The solution incorporates internal active management controls that not only optimizes the system environment for the given dynamic IT loads and changing system conditions, but also interfaces with data center Building Management Systems (BMS) to provide a complete end-to-end view of power and cooling chain. This technology achieves the goal of a Power Usage Effectiveness (PUE) of 1.25, resulting in a 38% reduction in the total amount of energy needed to support a 100KW IT load compared to current data center designs.

FMIT direct-current beam monitor

International Nuclear Information System (INIS)

Brousseau, A.T.; Chamberlin, D.D.

1981-01-01

The prototype injector section for the Fusion Materials Irradiation Test (FMIT) Facility being developed at the Los Alamos National Laboratory requires that beam parameters be noninterceptively monitored. This report describes the application of a single toroidal core, coupled with very simple circuitry, that results in the production of a simple instrument, and eliminates the problems inherent in the Faraday cup technique for the current measurements of the FMIT injector beam

A study of direct- and pulse-current chromium electroplating on rotating cylinder electrode (RCE)

International Nuclear Information System (INIS)

Chang, J.H.; Hsu, F.Y.; Liao, M.J.; Huang, C.A.

2007-01-01

Direct- and pulse-current (DC and PC) chromium electroplating on Cr-Mo steel were performed in a sulfate-catalyzed chromic acid solution at 50 deg. C using a rotating cylinder electrode (RCE). The electroplating cathodic current densities were at 30, 40, 50 and 60 A dm -2 , respectively. The relationship between electroplating current efficiency and the rotating speed of the RCE was studied. The cross-sectional microstructure of Cr-deposit was examined by transmission electron microscope (TEM). Results showed that DC-plating exhibited higher current efficiency than the PC-plating under the same conditions of electroplating current density and the rotating speed. We found the critical rotating speed of RCE used in the chromium electroplating, above this rotating speed the chromium deposition is prohibited. At the same plating current density, the critical rotating speed for DC-plating was higher than that for PC-plating. The higher plating current density is, the larger difference in critical rotating speeds appears between DC- and PC-electroplating. Equiaxed grains, in a nanoscale size with lower dislocation density, nucleate on the cathodic surface in both DC- and PC-electroplating. Adjacent to the equiaxed grains, textured grains were found in other portion of chromium deposit. Fine columnar grains were observed in the DC-electroplated deposit. On the other hand, very long slender grains with high degree of preferred orientation were detected in PC-electroplated deposit

Inductive current startup in large tokamaks with expanding minor radius and rf assist

International Nuclear Information System (INIS)

Borowski, S.K.

1984-02-01

Auxiliary rf heating of electrons before and during the current-rise phase of a large tokamak, such as the Fusion Engineering Device (R = 4.8 m, a = 1.3 m, sigma = 1.6, B/sub T/ = 3.62 T), is examined as a means of reducing both the initiation loop voltage and resistive flux expenditure during startup. Prior to current initiation, 1 to 2 MW of electron cyclotron resonance heating power at approx. 90 GHz is used to create a small volume of high conductivity plasma (T/sub e/ approx. = 100 eV, n/sub e/ approx. = 10 19 m -3 ) near the upper hybrid resonance (UHR) region. This plasma conditioning permits a small radius (a 0 approx. = 0.2 to 0.4 m) current channel to be established with a relatively low initial loop voltage (less than or equal to 25 V as opposed to approx. 100 V without rf assist). During the subsequent plasma expansion and current ramp phase, a combination of rf heating (up to 5 MW) and current profile control leads to a substantial savings in volt-seconds by: (1) minimizing the resistive flux consumption; and (2) maintaining the internal flux at or near the flat profile limit

Direct observations of the Antarctic Slope Current transport at 113°E

Science.gov (United States)

Peña-Molino, B.; McCartney, M. S.; Rintoul, S. R.

2016-10-01

The Antarctic Slope Current (ASC), defined here as the region of westward flow along the continental slope off Antarctica, forms the southern limb of the subpolar gyres. It regulates the exchange of water across the shelf break and provides a path for interbasin westward transport. Despite its significance, the ASC remains largely unobserved around most of the Antarctic continent. Here we present direct velocity observations from a 17 month current meter moored array deployed across the continental slope between the 1000 and the 4200 m isobaths, in the southeastern Indian Ocean near 113°E. The observed time-mean flow consists of a surface-intensified jet associated with the Antarctic Slope Front (ASF) and a broader bottom-intensified westward flow that extends out to approximately the 4000 m isobath and is strongest along the upper slope. The time-mean transport of the ASC is -29.2 Sv. Fluctuations in the transport are large, typically exceeding the mean by a factor of 2. They are mainly due to changes in the northward extent of the current over the lower slope. However, seasonal changes in the wind also drive variations in the transport of the ASF and the flow in the upper slope. Both mean and variability are largely barotropic, thus invisible to traditional geostrophic methods.

ANODAL TRANSCRANIAL DIRECT CURRENT STIMULATION (TDCS) INCREASES ISOMETRIC STRENGTH OF SHOULDER ROTATORS MUSCLES IN HANDBALL PLAYERS.

Science.gov (United States)

Hazime, Fuad Ahmad; da Cunha, Ronaldo Alves; Soliaman, Renato Rozenblit; Romancini, Ana Clara Bezerra; Pochini, Alberto de Castro; Ejnisman, Benno; Baptista, Abrahão Fontes

2017-06-01

Weakness of the rotator cuff muscles can lead to imbalances in the strength of shoulder external and internal rotators, change the biomechanics of the glenohumeral joint and predispose an athlete to injury. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that has demonstrated promising results in a variety of health conditions. However few studies addressed its potential approach in the realm of athletics. The purpose of this study was to investigate if transcranial direct current stimulation (tDCS) technique increases the isometric muscle strength of shoulder external and internal rotators in handball athletes. Randomized, double-blind, placebo-controlled, crossover study. Eight female handball players aged between 17 and 21 years (Mean=19.65; SD=2.55) with 7.1 ± 4.8 years of experience in training, participating in regional and national competitions were recruited. Maximal voluntary isometric contraction (MVIC) of shoulder external and internal rotator muscles was evaluated during and after 30 and 60 minutes post one session of anodal and sham current (2mA; 0.057mA/cm 2 ) with a one-week interval between stimulations. Compared to baseline, MVIC of shoulder external and internal rotators significantly increased after real but not sham tDCS. Between-group differences were observed for external and internal rotator muscles. Maximal voluntary isometric contraction of external rotation increased significantly during tDCS, and 30 and 60 minutes post-tDCS for real tDCS compared to that for sham tDCS. For internal rotation MVIC increased significantly during and 60 minutes post-tDCS. The results indicate that transcranial direct current stimulation temporarily increases maximal isometric contractions of the internal and external rotators of the shoulder in handball players. 2.

The Breakthrough Behind the Chevy Volt Battery

Science.gov (United States)

Lerner, Louise

2011-03-28

A revolutionary breakthrough cathode for lithium-ion batteries—the kind in your cell phone, laptop and new hybrid cars—makes them last longer, run more safely and perform better than batteries currently on the market.

An analysis of JET fast-wave heating and current drive experiments directly related to ITER

Energy Technology Data Exchange (ETDEWEB)

Bhatnagar, V P; Eriksson, L; Gormezano, C; Jacquinot, J; Kaye, A; Start, D F.H. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking

1994-07-01

The ITER fast-wave system is required to serve a variety of purposes, in particular, plasma heating to ignition, current profile and burn control and eventually, in conjunction with other schemes, a central non-inductive current drive (CD) for the steady-state operation of ITER. The ICRF heating and current drive data that has been obtained in JET are analyzed in terms of dimensionless parameters, with a view to ascertaining its direct relevance to key ITER requirements. The analysis is then used to identify areas both in physics and technological aspects of ion-cyclotron resonance heating (ICRH) and CD that require further experimentation in ITER-relevant devices such as JET to establish the required data base. (authors). 12 refs., 8 figs.

An analysis of JET fast-wave heating and current drive experiments directly related to ITER

International Nuclear Information System (INIS)

Bhatnagar, V.P.; Eriksson, L.; Gormezano, C.; Jacquinot, J.; Kaye, A.; Start, D.F.H.

1994-01-01

The ITER fast-wave system is required to serve a variety of purposes, in particular, plasma heating to ignition, current profile and burn control and eventually, in conjunction with other schemes, a central non-inductive current drive (CD) for the steady-state operation of ITER. The ICRF heating and current drive data that has been obtained in JET are analyzed in terms of dimensionless parameters, with a view to ascertaining its direct relevance to key ITER requirements. The analysis is then used to identify areas both in physics and technological aspects of ion-cyclotron resonance heating (ICRH) and CD that require further experimentation in ITER-relevant devices such as JET to establish the required data base. (authors). 12 refs., 8 figs

Direct current insulator based dielectrophoresis (DC-iDEP) microfluidic chip for blood plasma separation

OpenAIRE

Mohammadi, Mahdi

2015-01-01

Lab-on-a-Chip (LOC) integrated microfluidics has been a powerful tool for new developments in analytical chemistry. These microfluidic systems enable the miniaturization, integration and automation of complex biochemical assays through the reduction of reagent use and enabling portability.Cell and particle separation in microfluidic systems has recently gained significant attention in many sample preparations for clinical procedures. Direct-current insulator-based dielectrophoresis (DC-iDEP) ...

Maximum Bandwidth Enhancement of Current Mirror using Series-Resistor and Dynamic Body Bias Technique

Directory of Open Access Journals (Sweden)

V. Niranjan

2014-09-01

Full Text Available This paper introduces a new approach for enhancing the bandwidth of a low voltage CMOS current mirror. The proposed approach is based on utilizing body effect in a MOS transistor by connecting its gate and bulk terminals together for signal input. This results in boosting the effective transconductance of MOS transistor along with reduction of the threshold voltage. The proposed approach does not affect the DC gain of the current mirror. We demonstrate that the proposed approach features compatibility with widely used series-resistor technique for enhancing the current mirror bandwidth and both techniques have been employed simultaneously for maximum bandwidth enhancement. An important consequence of using both techniques simultaneously is the reduction of the series-resistor value for achieving the same bandwidth. This reduction in value is very attractive because a smaller resistor results in smaller chip area and less noise. PSpice simulation results using 180 nm CMOS technology from TSMC are included to prove the unique results. The proposed current mirror operates at 1Volt consuming only 102 µW and maximum bandwidth extension ratio of 1.85 has been obtained using the proposed approach. Simulation results are in good agreement with analytical predictions.

Effects of Transcranial Direct Current Stimulation (tDCS) on Behaviour and Electrophysiology of Language Production

Science.gov (United States)

Wirth, Miranka; Rahman, Rasha Abdel; Kuenecke, Janina; Koenig, Thomas; Horn, Helge; Sommer, Werner; Dierks, Thomas

2011-01-01

Excitatory anodal transcranial direct current stimulation (A-tDCS) over the left dorsal prefrontal cortex (DPFC) has been shown to improve language production. The present study examined neurophysiological underpinnings of this effect. In a single-blinded within-subject design, we traced effects of A-tDCS compared to sham stimulation over the left…

Transcranial direct current stimulation in obsessive-compulsive disorder: emerging clinical evidence and considerations for optimal montage of electrodes.

Science.gov (United States)

Senço, Natasha M; Huang, Yu; D'Urso, Giordano; Parra, Lucas C; Bikson, Marom; Mantovani, Antonio; Shavitt, Roseli G; Hoexter, Marcelo Q; Miguel, Eurípedes C; Brunoni, André R

2015-07-01

Neuromodulation techniques for obsessive-compulsive disorder (OCD) treatment have expanded with greater understanding of the brain circuits involved. Transcranial direct current stimulation (tDCS) might be a potential new treatment for OCD, although the optimal montage is unclear. To perform a systematic review on meta-analyses of repetitive transcranianal magnetic stimulation (rTMS) and deep brain stimulation (DBS) trials for OCD, aiming to identify brain stimulation targets for future tDCS trials and to support the empirical evidence with computer head modeling analysis. Systematic reviews of rTMS and DBS trials on OCD in Pubmed/MEDLINE were searched. For the tDCS computational analysis, we employed head models with the goal of optimally targeting current delivery to structures of interest. Only three references matched our eligibility criteria. We simulated four different electrodes montages and analyzed current direction and intensity. Although DBS, rTMS and tDCS are not directly comparable and our theoretical model, based on DBS and rTMS targets, needs empirical validation, we found that the tDCS montage with the cathode over the pre-supplementary motor area and extra-cephalic anode seems to activate most of the areas related to OCD.

Study of 2219 aluminum alloy using direct current A-TIG welding

Science.gov (United States)

Li, Hui; Zou, Jiasheng

2017-07-01

Direct current A-TIG (DCEN A-TIG) welding using special active agent had eliminated the pores and the oxidation of 2219 high-strength aluminum alloy in welding. Addition of AlF3-25% LiF active agent to DCEN A-TIG welding and arc morphology showed a trailing phenomenon. However, the change in arc morphology was not remarkable when AlF3-75% LiF active agent was added. Addition of AlF3-75% LiF active agent can refine the grain size of DCEN A-TIG joint. The mechanical properties of the weld were optimal at 10% AlF3-75% LiF active agent. Compared with AC TIG and AC A-TIG welding, DCEN A-TIG welding yielded better results for 2219 Al alloy.

A fast fault protection based on direction of bus-side capacitor discharge current for a high-surety power supply

DEFF Research Database (Denmark)

Li, Haijin; Chen, Min; Yang, Boping

2017-01-01

A short-circuit fault protection strategy based on the direction of bus-side capacitor discharge current for a high-surety power supply, known as Super Uninterruptable Power Supply (Super UPS), is studied in this paper. It consists of multiple energy sources and storage components. All energy...... strategy is necessary to keep the uninterruptable power for the critical load. In this paper, the characteristics of the short-circuit fault are analyzed first. Then, a fast short-circuit fault locating and isolating strategy based on the direction of the discharge current of the busside capacitors...

TIBER engineering test reactor (ETR) startup scenarios

International Nuclear Information System (INIS)

Blackfield, D.T.; Perkins, L.J.

1987-01-01

A time-dependent Tokamak Systems Code (TTSC) has been developed and used to examine various inductively driven startup scenarios for the TIBER reactor. Radially averaged particle and energy balance equations are solved. In addition, time varying currents in the PF and OH coils are determined from MHD equilibrium and volt-seconds considerations. Less than 20 MW of auxiliary power deposited in the electrons is required to obtain steady-state operations. For this scenario, less than 10% of the total volt-seconds capability is consumed during startup and the currents in the PF and OH coils do not appear to exceed stress limits. For every volt-second saved during startup, the burn time can be extended 14 seconds. 4 refs., 6 figs., 3 tabs

Slow oscillating transcranial direct current stimulation during sleep has a sleep-stabilizing effect in chronic insomnia: a pilot study.

Science.gov (United States)

Saebipour, Mohammad R; Joghataei, Mohammad T; Yoonessi, Ali; Sadeghniiat-Haghighi, Khosro; Khalighinejad, Nima; Khademi, Soroush

2015-10-01

Recent evidence suggests that lack of slow-wave activity may play a fundamental role in the pathogenesis of insomnia. Pharmacological approaches and brain stimulation techniques have recently offered solutions for increasing slow-wave activity during sleep. We used slow (0.75 Hz) oscillatory transcranial direct current stimulation during stage 2 of non-rapid eye movement sleeping insomnia patients for resonating their brain waves to the frequency of sleep slow-wave. Six patients diagnosed with either sleep maintenance or non-restorative sleep insomnia entered the study. After 1 night of adaptation and 1 night of baseline polysomnography, patients randomly received sham or real stimulation on the third and fourth night of the experiment. Our preliminary results show that after termination of stimulations (sham or real), slow oscillatory transcranial direct current stimulation increased the duration of stage 3 of non-rapid eye movement sleep by 33 ± 26 min (P = 0.026), and decreased stage 1 of non-rapid eye movement sleep duration by 22 ± 17.7 min (P = 0.028), compared with sham. Slow oscillatory transcranial direct current stimulation decreased stage 1 of non-rapid eye movement sleep and wake time after sleep-onset durations, together, by 55.4 ± 51 min (P = 0.045). Slow oscillatory transcranial direct current stimulation also increased sleep efficiency by 9 ± 7% (P = 0.026), and probability of transition from stage 2 to stage 3 of non-rapid eye movement sleep by 20 ± 17.8% (P = 0.04). Meanwhile, slow oscillatory transcranial direct current stimulation decreased transitions from stage 2 of non-rapid eye movement sleep to wake by 12 ± 6.7% (P = 0.007). Our preliminary results suggest a sleep-stabilizing role for the intervention, which may mimic the effect of sleep slow-wave-enhancing drugs. © 2015 European Sleep Research Society.

Causal Analysis of the Inadvertent Contact with an Uncontrolled Electrical Hazardous Energy Source (120 Volts AC)

Energy Technology Data Exchange (ETDEWEB)

David E. James; Dennis E. Raunig; Sean S. Cunningham

2014-10-01

On September 25, 2013, a Health Physics Technician (HPT) was performing preparations to support a pneumatic transfer from the HFEF Decon Cell to the Room 130 Glovebox in HFEF, per HFEF OI 3165 section 3.5, Field Preparations. This activity involves an HPT setting up and climbing a portable ladder to remove the 14-C meter probe from above ball valve HBV-7. The HPT source checks the meter and probe and then replaces the probe above HBV-7, which is located above Hood ID# 130 HP. At approximately 13:20, while reaching past the HBV-7 valve position indicator switches in an attempt to place the 14-C meter probe in the desired location, the HPT’s left forearm came in contact with one of the three sets of exposed terminals on the valve position indication switches for HBV 7. This resulted in the HPT receiving an electrical shock from a 120 Volt AC source. Upon moving the arm, following the electrical shock, the HPT noticed two exposed electrical connections on a switch. The HPT then notified the HFEF HPT Supervisor, who in turn notified the MFC Radiological Controls Manager and HFEF Operations Manager of the situation. Work was stopped in the area and the hazard was roped off and posted to prevent access to the hazard. The HPT was escorted by the HPT Supervisor to the MFC Dispensary and then preceded to CFA medical for further evaluation. The individual was evaluated and released without any medical restrictions. Causal Factor (Root Cause) A3B3C01/A5B2C08: - Knowledge based error/Attention was given to wrong issues - Written Communication content LTA, Incomplete/situation not covered The Causal Factor (root cause) was attention being given to the wrong issues during the creation, reviews, verifications, and actual performance of HFEF OI-3165, which covers the need to perform the weekly source check and ensure placement of the probe prior to performing a “rabbit” transfer. This resulted in the hazard not being identified and mitigated in the procedure. Work activities

Spermatogonial stem cell transplantation and male infertility: Current status and future directions.

Science.gov (United States)

Forbes, Connor M; Flannigan, Ryan; Schlegel, Peter N

2018-03-01

To summarise the current state of research into spermatogonial stem cell (SSC) therapies with a focus on future directions, as SSCs show promise as a source for preserving or initiating fertility in otherwise infertile men. We performed a search for publications addressing spermatogonial stem cell transplantation in the treatment of male infertility. The search engines PubMed and Google Scholar were used from 1990 to 2017. Search terms were relevant for spermatogonial stem cell therapies. Titles of publications were screened for relevance; abstracts were read, if related and full papers were reviewed for directly pertinent original research. In all, 58 papers were found to be relevant to this review, and were included in appropriate subheadings. This review discusses the various techniques that SSCs are being investigated to treat forms of male infertility. Evidence does not yet support clinical application of SSCs in humans. However, significant progress in the in vitro and in vivo development of SSCs, including differentiation into functional germ cells, gives reason for cautious optimism for future research.

Modeling of Pulsed Direct-Current Glow Discharge

International Nuclear Information System (INIS)

Du Mu; Zheng Yaru; Fan Yujia; Zhang Nan; Liu Chengsen; Wang Dezhen

2010-01-01

A self-consistent model was adopted to study the time evolution of low-voltage pulsed DC glow discharge. The distributions of electric field, ion density and electron density in nitrogen were investigated in our simulation, and the temporal shape of the discharge current was also obtained. Our results show that the dynamic behaviors of the discharge depends strongly on the applied pulse voltage, and the use of higher pulse voltages results in a significantly increase of discharge current and a decrease of discharge delay time. The current-voltage characteristic calculated by adjusting secondary electron emission coefficient for different applied pulse voltage under the gas pressure of 1 Torr is found in a reasonable agreement with the experimental results.

Regenerating the human heart: direct reprogramming strategies and their current limitations.

Science.gov (United States)

Ghiroldi, Andrea; Piccoli, Marco; Ciconte, Giuseppe; Pappone, Carlo; Anastasia, Luigi

2017-10-27

Cardiovascular diseases are the leading cause of death in the Western world. Unfortunately, current therapies are often only palliative, consequently essentially making heart transplantation necessary for many patients. However, several novel therapeutic approaches in the past two decades have yielded quite encouraging results. The generation of induced pluripotent stem cells, through the forced expression of stem cell-specific transcription factors, has inspired the most promising strategies for heart regeneration by direct reprogramming of cardiac fibroblasts into functional cardiomyocytes. Initial attempts at this reprogramming were conducted using a similar approach to the one used with transcription factors, but during years, novel strategies have been tested, e.g., miRNAs, recombinant proteins and chemical molecules. Although preliminary results on animal models are promising, the low reprogramming efficiency, as well as the incomplete maturation of the cardiomyocytes, still represents important obstacles. This review covers direct transdifferentiation strategies that have been proposed and developed and illustrates the pros and cons of each approach. Indeed, as described in the manuscript, there are still many unanswered questions and drawbacks that require a better understanding of the basic signaling pathways and transcription factor networks before functional cells, suitable for cardiac regeneration and safe for the patients, can be generated and used for human therapies.

Notes on Human Trials of Transcranial Direct Current Stimulation between 1960 and 1998

Science.gov (United States)

Esmaeilpour, Zeinab; Schestatsky, Pedro; Bikson, Marom; Brunoni, André R.; Pellegrinelli, Ada; Piovesan, Fernanda X.; Santos, Mariana M. S. A.; Menezes, Renata B.; Fregni, Felipe

2017-01-01

Background: Transcranial direct current stimulation (tDCS) is investigated to modulate neuronal function including cognitive neuroscience and neuropsychiatric therapies. While cases of human stimulation with rudimentary batteries date back more than 200 years, clinical trials with current controlled stimulation were published intermittently since the 1960s. The modern era of tDCS only started after 1998. Objectives: To review methods and outcomes of tDCS studies from old literature (between 1960 and 1998) with intention of providing new insight for ongoing tDCS trials and development of tDCS protocols especially for the purpose of treatment. Methods: Articles were identified through a search in PubMed and through the reference list from its selected articles. We included only non-invasive human studies that provided controlled direct current and were written in English, French, Spanish or Portuguese before the year of 1998, the date in which modern stimulation paradigms were implemented. Results: Fifteen articles met our criteria. The majority were small-randomized controlled clinical trials that enrolled a mean of approximately 26 subjects (Phase II studies). Most of the studies (around 83%) assessed the role of tDCS in the treatment of psychiatric conditions, in which the main outcomes were measured by means of behavioral scales and clinical observation, but the diagnostic precision and the quality of outcome monitoring, including adverse events, were deficient by modern standards. Compared to modern tDCS dose, the stimulation intensities used (0.1–1 mA) were lower, however as the electrodes were typically smaller (e.g., 1.26 cm2), the average electrode current density (0.2 mA/cm2) was approximately 4× higher. The number of sessions ranged from one to 120 (median 14). Notably, the stimulation session durations of several minutes to 11 h (median 4.5 h) could markedly exceed modern tDCS protocols. Twelve studies out of 15 showed positive results. Only mild side

Direct-Current Forced Interruption and Breaking Performance of Spiral-Type Contacts in Aero Applications

Directory of Open Access Journals (Sweden)

Wenlei Huo

2017-05-01

Full Text Available This paper analyses the transient characteristics and breaking performance of direct-current (DC forced-interruption vacuum interrupters in 270 V power-supply systems. Three stages are identified in forced interruption: the DC-arcing stage, current-commutation stage, and voltage-recovery stage. During the current-commutation stage, the reverse peak-current coefficient k, which is a key design factor, is used to calculate the rate of current at zero-crossing (di/dt. MATLAB/Simulink simulation models are established to obtain the transient characteristics influenced by the forced-commutation branch parameters and the coefficient k. To study the breaking performance of spiral-type contacts, experiments are conducted for different contact materials and arcing times for currents less than 3.5 kA. During the DC-arcing stage, a locally intensive burning arc is observed in the CuW80 contact; however, it is not observed in the CuCr50 contact. On examining the re-ignition interruption results of the CuW80 contact, the intensive burning arc is found to be positioned within a possible re-ignition region. When the arcing time is longer than 1 ms, the intensive burning arc occurs and affects the breaking performance of the spiral-type contacts. If the DC-arcing stage is prolonged, the total arcing energy increases, which leads to a lower breaking capacity.

Effects of Dual Transcranial Direct Current Stimulation for Aphasia in Chronic Stroke Patients

OpenAIRE

Lee, Seung Yeol; Cheon, Hee-Jung; Yoon, Kyoung Jae; Chang, Won Hyuk; Kim, Yun-Hee

2013-01-01

Objective To investigate any additional effect of dual transcranial direct current stimulation (tDCS) compared with single tDCS in chronic stroke patients with aphasia. Methods Eleven chronic stroke patients (aged 52.6?13.4 years, nine men) with aphasia were enrolled. Single anodal tDCS was applied over the left inferior frontal gyrus (IFG) and a cathodal electrode was placed over the left buccinator muscle. Dual tDCS was applied as follows: 1) anodal tDCS over the left IFG and cathodal tDCS ...

Effect of transcranial direct current stimulation on vestibular-ocular and vestibulo-perceptual thresholds.

Science.gov (United States)

Kyriakareli, Artemis; Cousins, Sian; Pettorossi, Vito E; Bronstein, Adolfo M

2013-10-02

Transcranial direct current stimulation (tDCS) was used in 17 normal individuals to modulate vestibulo-ocular reflex (VOR) and self-motion perception rotational thresholds. The electrodes were applied over the temporoparietal junction bilaterally. Both vestibular nystagmic and perceptual thresholds were increased during as well as after tDCS stimulation. Body rotation was labeled as ipsilateral or contralateral to the anode side, but no difference was observed depending on the direction of rotation or hemisphere polarity. Threshold increase during tDCS was greater for VOR than for motion perception. 'Sham' stimulation had no effect on thresholds. We conclude that tDCS produces an immediate and sustained depression of cortical regions controlling VOR and movement perception. Temporoparietal areas appear to be involved in vestibular threshold modulation but the differential effects observed between VOR and perception suggest a partial dissociation between cortical processing of reflexive and perceptual responses.

Direct and pulsed current annealing of p-MOSFET based dosimeter: the "MOSkin".

Science.gov (United States)

Alshaikh, Sami; Carolan, Martin; Petasecca, Marco; Lerch, Michael; Metcalfe, Peter; Rosenfeld, Anatoly

2014-06-01

Contemporary radiation therapy (RT) is complicated and requires sophisticated real-time quality assurance (QA). While 3D real-time dosimetry is most preferable in RT, it is currently not fully realised. A small, easy to use and inexpensive point dosimeter with real-time and in vivo capabilities is an option for routine QA. Such a dosimeter is essential for skin, in vivo or interface dosimetry in phantoms for treatment plan verification. The metal-oxide-semiconductor-field-effect-transistor (MOSFET) detector is one of the best choices for these purposes, however, the MOSFETs sensitivity and its signal stability degrade after essential irradiation which limits its lifespan. The accumulation of positive charge on the gate oxide and the creation of interface traps near the silicon-silicon dioxide layer is the primary physical phenomena responsible for this degradation. The aim of this study is to investigate MOSFET dosimeter recovery using two proposed annealing techniques: direct current (DC) and pulsed current (PC), both based on hot charged carrier injection into the gate oxide of the p-MOSFET dosimeter. The investigated MOSFETs were reused multiple times using an irradiation-annealing cycle. The effect of the current-annealing parameters was investigated for the dosimetric characteristics of the recovered MOSFET dosimeters such as linearity, sensitivity and initial threshold voltage. Both annealing techniques demonstrated excellent results in terms of maintaining a stable response, linearity and sensitivity of the MOSFET dosimeter. However, PC annealing is more preferable than DC annealing as it offers better dose response linearity of the reused MOSFET and has a very short annealing time.

Universal "Imaginary Closed Circuit Method" and Formula for Determination of Direction of Induced EMF/Current

Science.gov (United States)

Atram, Dattatraya Balaram

2011-01-01

Fleming's right-hand rule and the right-flat-hand rule are generally applied for determining the direction of flow of induced emf/current in straight conductors. The right-hand-fingers rule is applied for coils only. The right-hand-thumb rule can be applied for either straight conductors or coils. Different rules have to be applied for different…

Culture, mind, and the brain: current evidence and future directions.

Science.gov (United States)

Kitayama, Shinobu; Uskul, Ayse K

2011-01-01

Current research on culture focuses on independence and interdependence and documents numerous East-West psychological differences, with an increasing emphasis placed on cognitive mediating mechanisms. Lost in this literature is a time-honored idea of culture as a collective process composed of cross-generationally transmitted values and associated behavioral patterns (i.e., practices). A new model of neuro-culture interaction proposed here addresses this conceptual gap by hypothesizing that the brain serves as a crucial site that accumulates effects of cultural experience, insofar as neural connectivity is likely modified through sustained engagement in cultural practices. Thus, culture is "embrained," and moreover, this process requires no cognitive mediation. The model is supported in a review of empirical evidence regarding (a) collective-level factors involved in both production and adoption of cultural values and practices and (b) neural changes that result from engagement in cultural practices. Future directions of research on culture, mind, and the brain are discussed.

Specific features of the behaviour of excess currents in tunnel diodes of n-GaAs

International Nuclear Information System (INIS)

Vyatkin, A.P.; Glushchenko, V.A.; Parkhomenko, R.P.; Pastor, A.P.

1981-01-01

The behaviour of currents in the field of a valley of volt-ampere characteristics (VAC) and the effect of 2.0 MeV electron bombardment on the characteristics of tunnel n-GaAs of TD diodes is considered. Release of tunnel and thermal current components has shown that the first component of excess currents is due to electron tunneling through intermediate states situated in a wide region of the forbidden zone. The nature of the second current component is explained by far reaching into the region of the forbidden zone tails of electron states on which energy impurity states can superimpose. Highly-alloyed TD with concentrations n>=3x10 19 cm -3 and p=(1.5-2)x10 20 cm -3 practically are not sensitive to doses up to phi approximately 2x10 17 el/cm 2 . Radiation induced defects related with electron bombardment is rather small. Specific features of the preparation of n-GaAs tunnel diodes lead to the fact that as a result of complex alloying of the p-region of the diode a relatively slow increase of excess currents as compared with the TD corresponding currents from the p-GaAs is observed

Adaptive threshold hunting for the effects of transcranial direct current stimulation on primary motor cortex inhibition.

Science.gov (United States)

Mooney, Ronan A; Cirillo, John; Byblow, Winston D

2018-06-01

Primary motor cortex excitability can be modulated by anodal and cathodal transcranial direct current stimulation (tDCS). These neuromodulatory effects may, in part, be dependent on modulation within gamma-aminobutyric acid (GABA)-mediated inhibitory networks. GABAergic function can be quantified non-invasively using adaptive threshold hunting paired-pulse transcranial magnetic stimulation (TMS). The previous studies have used TMS with posterior-anterior (PA) induced current to assess tDCS effects on inhibition. However, TMS with anterior-posterior (AP) induced current in the brain provides a more robust measure of GABA-mediated inhibition. The aim of the present study was to assess the modulation of corticomotor excitability and inhibition after anodal and cathodal tDCS using TMS with PA- and AP-induced current. In 16 young adults (26 ± 1 years), we investigated the response to anodal, cathodal, and sham tDCS in a repeated-measures double-blinded crossover design. Adaptive threshold hunting paired-pulse TMS with PA- and AP-induced current was used to examine separate interneuronal populations within M1 and their influence on corticomotor excitability and short- and long-interval inhibition (SICI and LICI) for up to 60 min after tDCS. Unexpectedly, cathodal tDCS increased corticomotor excitability assessed with AP (P = 0.047) but not PA stimulation (P = 0.74). SICI AP was reduced after anodal tDCS compared with sham (P = 0.040). Pearson's correlations indicated that SICI AP and LICI AP modulation was associated with corticomotor excitability after anodal (P = 0.027) and cathodal tDCS (P = 0.042). The after-effects of tDCS on corticomotor excitability may depend on the direction of the TMS-induced current used to make assessments, and on modulation within GABA-mediated inhibitory circuits.

Using transcranial direct-current stimulation (tDCS) to understand cognitive processing.

Science.gov (United States)

Reinhart, Robert M G; Cosman, Josh D; Fukuda, Keisuke; Woodman, Geoffrey F

2017-01-01

Noninvasive brain stimulation methods are becoming increasingly common tools in the kit of the cognitive scientist. In particular, transcranial direct-current stimulation (tDCS) is showing great promise as a tool to causally manipulate the brain and understand how information is processed. The popularity of this method of brain stimulation is based on the fact that it is safe, inexpensive, its effects are long lasting, and you can increase the likelihood that neurons will fire near one electrode and decrease the likelihood that neurons will fire near another. However, this method of manipulating the brain to draw causal inferences is not without complication. Because tDCS methods continue to be refined and are not yet standardized, there are reports in the literature that show some striking inconsistencies. Primary among the complications of the technique is that the tDCS method uses two or more electrodes to pass current and all of these electrodes will have effects on the tissue underneath them. In this tutorial, we will share what we have learned about using tDCS to manipulate how the brain perceives, attends, remembers, and responds to information from our environment. Our goal is to provide a starting point for new users of tDCS and spur discussion of the standardization of methods to enhance replicability.

Food waste-to-energy conversion technologies: current status and future directions.

Science.gov (United States)

Pham, Thi Phuong Thuy; Kaushik, Rajni; Parshetti, Ganesh K; Mahmood, Russell; Balasubramanian, Rajasekhar

2015-04-01

Food waste represents a significantly fraction of municipal solid waste. Proper management and recycling of huge volumes of food waste are required to reduce its environmental burdens and to minimize risks to human health. Food waste is indeed an untapped resource with great potential for energy production. Utilization of food waste for energy conversion currently represents a challenge due to various reasons. These include its inherent heterogeneously variable compositions, high moisture contents and low calorific value, which constitute an impediment for the development of robust, large scale, and efficient industrial processes. Although a considerable amount of research has been carried out on the conversion of food waste to renewable energy, there is a lack of comprehensive and systematic reviews of the published literature. The present review synthesizes the current knowledge available in the use of technologies for food-waste-to-energy conversion involving biological (e.g. anaerobic digestion and fermentation), thermal and thermochemical technologies (e.g. incineration, pyrolysis, gasification and hydrothermal oxidation). The competitive advantages of these technologies as well as the challenges associated with them are discussed. In addition, the future directions for more effective utilization of food waste for renewable energy generation are suggested from an interdisciplinary perspective. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of alternating and direct electrical current application on the odontoblastic layer in human teeth : an in vitro study

NARCIS (Netherlands)

Alwas-Danowska, HM; Huysmans, MCDNJM; Verdonschot, EH

Aim The aim of this study was to investigate the influence of a low intensity alternating current on the odontoblasts and odontoblast layer and compare this with the effects of a direct current. Methodology Teeth extracted for orthodontic were immersed in physiological saline stabilized with thymol

Suspended sediment dynamics in a large-scale turbidity current: Direct measurements from the deep-water Congo Canyon

Science.gov (United States)

Simmons, S.; Azpiroz, M.; Cartigny, M.; Clare, M. A.; Parsons, D. R.; Sumner, E.; Talling, P. J.

2016-12-01

Turbidity currents that transport sediment to the deep ocean deposit a greater volume of sediment than any other process on Earth. To date, only a handful of studies have directly measured turbidity currents, with flow durations ranging from a few minutes to a few hours. Our understanding of turbidity current dynamics is therefore largely derived from scaled laboratory experiments and numerical modelling. Recent years have seen the first field-scale measurements of depth-resolved velocity profiles, but sediment concentration (a key parameter for turbidity currents) remains elusive. Here, we present high resolution measurements of deep-water turbidity currents from the Congo Canyon; one of the world's largest submarine canyons. Direct measurements using acoustic Doppler current profilers (ADCPs) show that flows can last for many days, rather than hours as seen elsewhere, and provide the first quantification of concentration and grain size within deep-water turbidity currents.Velocity and backscatter were measured at 5 second intervals by an ADCP suspended 80 m above the canyon floor, at 2000 m water depth. A novel inversion method using multiple ADCP frequencies enabled quantification of sediment concentration and grain size within the flows. We identify high concentrations of coarse sediment within a thin frontal cell, which outruns a thicker, trailing body. Thus, the flows grow in length while propagating down-canyon. This is distinct from classical models and other field-scale measurements of turbidity currents. The slow-moving body is dominated by suspended fine-grained sediment. The body mixes with the surrounding fluid leaving diffuse clouds of sediment that persist for days after initial entrainment. Ambient tidal flow also controls the mixing within the body and the surrounding fluid. Our results provide a new quantification of suspended sediment within flows and the interaction with the surrounding fluid.

Current direction, temperature, and other data from moored current meter casts in the Gulf of Mexico during the Brine Disposal project, 1979-05-15 to 1980-03-22 (NODC Accession 8000457)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature, salinity, current direction, and other data were collected using moored current meter casts from the EXCELLENCE in the Gulf of Mexico from May 15, 1979...

Clinical effectiveness of primary and secondary headache treatment by transcranial direct current stimulation

Directory of Open Access Journals (Sweden)

Dmitry ePinchuk

2013-03-01

Full Text Available The clinical effectiveness of headache treatment by transcranial direct current stimulation with various locations of stimulating electrodes on the scalp was analyzed retrospectively. The results of the treatment were analyzed in 90 patients aged from 19 to 54 years (48 patients had migraine without aura, 32 – frequent episodic tension-type headaches, 10 – chronic tension-type headaches and in 44 adolescents aged 11 – 16 years with chronic posttraumatic headaches after a mild head injury. Clinical effectiveness of tDCS with 70 – 150 µA current for 30 – 45 minutes via 6.25 cm2 stimulating electrodes is comparable to that of modern pharmacological drugs, with no negative side effects. The obtained result has been maintained on average from 5 to 9 months. It has been demonstrated that effectiveness depends on localization of stimulating electrodes used for different types of headaches.

Transcranial Direct Current Stimulation (tDCS): A Promising Treatment for Major Depressive Disorder?

Science.gov (United States)

Bennabi, Djamila; Haffen, Emmanuel

2018-01-01

Background: Transcranial direct current stimulation (tDCS) opens new perspectives in the treatment of major depressive disorder (MDD), because of its ability to modulate cortical excitability and induce long-lasting effects. The aim of this review is to summarize the current status of knowledge regarding tDCS application in MDD. Methods: In this review, we searched for articles published in PubMed/MEDLINE from the earliest available date to February 2018 that explored clinical and cognitive effects of tDCS in MDD. Results: Despite differences in design and stimulation parameters, the examined studies indicated beneficial effects of tDCS for MDD. These preliminary results, the non-invasiveness of tDCS, and its good tolerability support the need for further research on this technique. Conclusions: tDCS constitutes a promising therapeutic alternative for patients with MDD, but its place in the therapeutic armamentarium remains to be determined. PMID:29734768

Adjoint optimization scheme for lower hybrid current rampup and profile control in Tokamak

International Nuclear Information System (INIS)

Litaudon, X.; Moreau, D.; Bizarro, J.P.; Hoang, G.T.; Kupfer, K.; Peysson, Y.; Shkarofsky, I.P.; Bonoli, P.

1992-12-01

The purpose of this work is to take into account and study the effect of the electric field profiles on the Lower Hybrid (LH) current drive efficiency during transient phases such as rampup. As a complement to the full ray-tracing / Fokker Planck studies, and for the purpose of optimization studies, we developed a simplified 1-D model based on the adjoint Karney-Fisch numerical results. This approach allows us to estimate the LH power deposition profile which would be required for ramping the current with prescribed rate, total current density profile (q-profile) and surface loop voltage. For rampup optimization studies, we can therefore scan the whole parameter space and eliminate a posteriori those scenarios which correspond to unrealistic deposition profiles. We thus obtain the time evolution of the LH power, minor radius of the plasma, volt-second consumption and total energy dissipated. Optimization can thus be performed with respect to any of those criteria. This scheme is illustrated by some numerical simulations performed with TORE-SUPRA and NET/ITER parameters. We conclude with a derivation of a simple and general scaling law for the flux consumption during the rampup phase

Effects of transcranial direct current stimulation over left dorsolateral pFC on the attentional blink depend on individual baseline performance

NARCIS (Netherlands)

London, R.E.; Slagter, H.A.

2015-01-01

Selection mechanisms that dynamically gate only relevant perceptual information for further processing and sustained representation in working memory are critical for goal-directed behavior. We examined whether this gating process can be modulated by anodal transcranial direct current stimulation

Research on corrosion mechanism of suspension insulator steel foot of direct current system and measures for corrosion inhibition

Science.gov (United States)

Chen, He; Yang, Yueguang; Su, Guolei; Wang, Xiaoqing; Zhang, Hourong; Sun, Xiaoyu; Fan, Youping

2017-09-01

There are increasingly serious electrocorrosion phenomena on insulator hardware caused by direct current transmission due to the wide-range popularization of extra high voltage direct current transmission engineering in our country. Steel foot corrosion is the main corrosion for insulators on positive polarity side of transmission lines. On one hand, the corrosion leads to the tapering off of steel foot diameter, having a direct influence on mechanical property of insulators; on the other hand, in condition of corrosion on steel foot wrapped in porcelain ware, the volume of the corrosion product is at least 50% more than that of the original steel foot, leading to bursting of porcelain ware, threatening safe operation of transmission lines. Therefore, it is necessary to conduct research on the phenomenon and propose feasible measures for corrosion inhibition. Starting with the corrosion mechanism, this article proposes two measures for corrosion inhibition, and verifies the inhibition effect in laboratory conditions, providing reference for application in engineering.

Direct Current as an Integrating Platform for ZNE Buildings with EVs and Storage: DC Direct Systems – A Bridge to a Low Carbon Future?

Energy Technology Data Exchange (ETDEWEB)

Johnson, Karl [California Inst. for Energy and the Environment, Berkeley, CA (United States); Vossos, Vagelis [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kloss, Margarita [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Robinson, Gerald [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Brown, Rich [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2016-09-01

Cost effective zero net energy (ZNE) schemes exist for many types of residential and commercial buildings. Yet, today’s alternating current (AC) based ZNE designs may be as much as 10% to 20% less efficient, more costly, and more complicated than a design based on direct current (DC) technologies. An increasing number of research organizations and manufacturers are just starting the process of developing products and conducting research and development (R&D) efforts. These early R&D efforts indicate that the use of DC technologies may deliver many energy and non-energy benefits relative to AC-based typologies. DC ZNE schemes may provide for an ideal integrating platform for natively DC-based onsite generation, storage, electric vehicle (EV) charging and end-use loads. Emerging empirical data suggest that DC end-use appliances are more efficient, simpler, more durable, and lower cost. DC technologies appear to provide ratepayers a lower cost pathway to achieve resilient ZNE buildings, and simultaneously yield a plethora of benefits. This paper draws from the current research effort entitled "Direct Current as an Integrating and Enabling Platform," co-led by the Lawrence Berkeley National Laboratory (LBNL), the California Institute for Energy and the Environment (CIEE), the Electric Power Research Institute (EPRI) and funded under the California Energy Commission’s Energy Program Investment Charge (CEC EPIC). The first phase of this EPIC research is focused on assembling and summarizing known global performance information on DC and DC-AC hybrid end-use appliances and power systems. This paper summarizes the information and insights gained from this research effort.

Current direction, temperature, and salinity data from moored current meter casts in the Gulf of Mexico during the Brine Disposal project, 1983-08-31 to 1984-10-01 (NODC Accession 8500021)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, temperature, and salinity data were collected using moored current meter casts in the Gulf of Mexico from August 31, 1983 to October 1, 1984. Data...

Current frontiers and future directions of telecoupling research

Science.gov (United States)

Liu, J.

2016-12-01

The world has been increasingly interconnected over long distances though processes such as international trade, migration, telecommunication, and disease spread. However, previous studies often focused on socioeconomic or environmental issues of distant processes. While these studies have generated useful information for individual disciplines, integrating socioeconomic and environmental information is essential for holistic understanding of complex global challenges and unbiased decision making to address the challenges. To advance integrated research, the framework of telecoupling (socioeconomic and environmental interactions over distances) has been developed to explicitly address both socioeconomic and environmental issues simultaneously. Although the framework is relatively new, it has already been applied to tackle a variety of globally important issues, such as food security, water resources, energy sustainability, land use, international trade (e.g., food, forest products, energy, wildlife, industrial products), species invasion, investment, ecosystem services, conservation, information dissemination, and tourism. These applications have identified many important research gaps (e.g. spillover systems) and hidden linkages (e.g. feedbacks) among distant areas of the world with profound implications for sustainable development, ecosystem health, and human well-being. While working with telecoupling presents more challenges than focusing only on disciplinary issues, support from funding agencies has helped accelerate research on telecoupling and more efforts are being aimed at framework quantification and operationalization. The presenter will provide an overview of the current frontiers, discuss future research directions, and highlight emerging opportunities and challenges in telecoupling research and governance.

Direct-current cathodic vacuum arc system with magnetic-field mechanism for plasma stabilization.

Science.gov (United States)

Zhang, H-S; Komvopoulos, K

2008-07-01

Filtered cathodic vacuum arc (FCVA) deposition is characterized by plasma beam directionality, plasma energy adjustment via substrate biasing, macroparticle filtering, and independent substrate temperature control. Between the two modes of FCVA deposition, namely, direct current (dc) and pulsed arc, the dc mode yields higher deposition rates than the pulsed mode. However, maintaining the dc arc discharge is challenging because of its inherent plasma instabilities. A system generating a special configuration of magnetic field that stabilizes the dc arc discharge during film deposition is presented. This magnetic field is also part of the out-of-plane magnetic filter used to focus the plasma beam and prevent macroparticle film contamination. The efficiency of the plasma-stabilizing magnetic-field mechanism is demonstrated by the deposition of amorphous carbon (a-C) films exhibiting significantly high hardness and tetrahedral carbon hybridization (sp3) contents higher than 70%. Such high-quality films cannot be produced by dc arc deposition without the plasma-stabilizing mechanism presented in this study.

Direct-current cathodic vacuum arc system with magnetic-field mechanism for plasma stabilization

International Nuclear Information System (INIS)

Zhang, H.-S.; Komvopoulos, K.

2008-01-01

Filtered cathodic vacuum arc (FCVA) deposition is characterized by plasma beam directionality, plasma energy adjustment via substrate biasing, macroparticle filtering, and independent substrate temperature control. Between the two modes of FCVA deposition, namely, direct current (dc) and pulsed arc, the dc mode yields higher deposition rates than the pulsed mode. However, maintaining the dc arc discharge is challenging because of its inherent plasma instabilities. A system generating a special configuration of magnetic field that stabilizes the dc arc discharge during film deposition is presented. This magnetic field is also part of the out-of-plane magnetic filter used to focus the plasma beam and prevent macroparticle film contamination. The efficiency of the plasma-stabilizing magnetic-field mechanism is demonstrated by the deposition of amorphous carbon (a-C) films exhibiting significantly high hardness and tetrahedral carbon hybridization (sp 3 ) contents higher than 70%. Such high-quality films cannot be produced by dc arc deposition without the plasma-stabilizing mechanism presented in this study

Corrosion study on high power feeding of telecomunication copper cable in 5 wt.% CaSO4.2H2O solution

Science.gov (United States)

Shamsudin, Shaiful Rizam; Hashim, Nabihah; Ibrahim, Mohd Saiful Bahri; Rahman, Muhammad Sayuzi Abdul; Idrus, Muhammad Amin; Hassan, Mohd Rezadzudin; Abdullah, Wan Razli Wan

2016-07-01

The studies were carried out to find out the best powering scheme over the copper telephone line. It was expected that the application of the higher power feeding could increase the data transfer and capable of providing the customer's satisfaction. To realize the application of higher remote power feeding, the potential of corrosion problem on Cu cables was studied. The natural corrosion behaviour of copper cable in the 0.5% CaSO4.2H2O solution was studied in term of open circuit potential for 30 days. The corrosion behaviour of higher power feeding was studied by the immersion and the planned interval test to determine the corrosion rate as well as the effect of voltage magnitudes and the current scheme i.e. positive direct (DC+) and alternating current (AC) at about 0.40 ± 0.01 mA/ cm2 current density. In the immersion test, both DC+ and AC scheme showed the increasing of feeding voltage magnitude has increased the corrosion rate of Cu samples starting from 60 to 100 volts. It was then reduced at about 100 - 120 volts which may due to the passive and transpassive mechanism. The corrosion rate was slowly reduced further from 120 to 200 volts. Visually, the positively charged of Cu cable was seems susceptible to severe corrosion, while AC scheme exhibited a slight corrosion reaction on the surface. However, the planned interval test and XRD results showed the corrosion activity of the copper cable in the studied solution was a relatively slow process and considered not to be corroded as a partially protective scale of copper oxide formed on the surface.

Axial mercury segregation in direct current operated low-pressure argon-mercury gas discharge: Part I. Experimental

NARCIS (Netherlands)

Gielen, J.W.A.M.; de Groot, S.; Dijk, van J.; Mullen, van der J.J.A.M.

2004-01-01

Due to cataphoresis, axial segregation of mercury will occur when the gas discharge of a fluorescent lamp is operated by means of a direct current. A consequence of this is a non-uniform axial luminance distribution along the lamp. To determine the degree of axial mercury segregation experimentally,

Inductive current startup in large tokamaks with expanding minor radius and RF assist

International Nuclear Information System (INIS)

Borowski, S.K.

1983-01-01

Auxiliary RF heating of electrons before and during the current rise phase of a large tokamak, such as the Fusion Engineering Device, is examined as a means of reducing both the initiation loop voltage and resistive flux expenditure during startup. Prior to current initiation, 1 to 2 MW of electron cyclotron resonance heating power at approx.90 GHz is used to create a small volume of high conductivity plasma (T/sub e/ approx. = 100 eV, n/sub e/ approx. = 10 19 m -3 ) near the upper hybrid resonance (UHR) region. This plasma conditioning permits a small radius (a 0 approx.< 0.4 m) current channel to be established with a relatively low initial loop voltage (approx.< 25 V as opposed to approx.100 V without RF assist). During the subsequent plasma expansion and current ramp phase, additional RF power is introduced to reduce volt-second consumption due to plasma resistance. To study the preheating phase, a near classical particle and energy transport model is developed to estimate the electron heating efficiency in a currentless toroidal plasma. The model assumes that preferential electron heating at the UHR leads to the formation of an ambipolar sheath potential between the neutral plasma and the conducting vacuum vessel and limiter

Current direction, wind wave spectra, and CTD data from moored current meter and CTD casts in the North Atlantic Ocean from 1982-09-15 to 1983-09-15 (NODC Accession 8500148)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, wind wave spectra, and CTD data were collected using moored current meter and CTD casts in the Gulf of Mexico from September 3, 1982 to September...

High magnetic field science and its application in the United States current status and future directions

CERN Document Server

National Research Council of the National Academies

2013-01-01

The Committee to Assess the Current Status and Future Direction of High Magnetic Field Science in the United States was convened by the National Research Council in response to a request by the National Science Foundation. This report answers three questions: (1) What is the current state of high-field magnet science, engineering, and technology in the United States, and are there any conspicuous needs to be addressed? (2) What are the current science drivers and which scientific opportunities and challenges can be anticipated over the next ten years? (3) What are the principal existing and planned high magnetic field facilities outside of the United States, what roles have U.S. high field magnet development efforts played in developing those facilities, and what potentials exist for further international collaboration in this area? A magnetic field is produced by an electrical current in a metal coil. This current exerts an expansive force on the coil, and a magnetic field is "high" if it challenges the str...

Coordinated Volt/Var Control in Distribution Systems with Distributed Generations Based on Joint Active and Reactive Powers Dispatch

Directory of Open Access Journals (Sweden)

Abouzar Samimi

2016-01-01

Full Text Available One of the most significant control schemes in optimal operation of distribution networks is Volt/Var control (VVC. Owing to the radial structure of distribution systems and distribution lines with a small X/R ratio, the active power scheduling affects the VVC issue. A Distribution System Operator (DSO procures its active and reactive power requirements from Distributed Generations (DGs along with the wholesale electricity market. This paper proposes a new operational scheduling method based on a joint day-ahead active/reactive power market at the distribution level. To this end, based on the capability curve, a generic reactive power cost model for DGs is developed. The joint active/reactive power dispatch model presented in this paper motivates DGs to actively participate not only in the energy markets, but also in the VVC scheme through a competitive market. The proposed method which will be performed in an offline manner aims to optimally determine (i the scheduled active and reactive power values of generation units; (ii reactive power values of switched capacitor banks; and (iii tap positions of transformers for the next day. The joint active/reactive power dispatch model for daily VVC is modeled in GAMS and solved with the DICOPT solver. Finally, the plausibility of the proposed scheduling framework is examined on a typical 22-bus distribution test network over a 24-h period.

College Advising: Current Perceptions, Future Directions.

Science.gov (United States)

Chapman, David W.; Gill, Stephen J.

1981-01-01

Examines the college admissions activities that high school counselors believe are most effective in providing accurate information to students. Also examines the current role of the counselor in college advising and reports on what counselors predict will be the trends in college advising. (Author/RC)

Cellular Mechanisms of Transcranial Direct Current Stimulation

Science.gov (United States)

2016-07-14

fEPSP responses are significantly (P < 0.05, *) facilitated with +8 V/m fields ( left ) and reduced with -8 V/m ( right ) in three pathways. In each...cortex results in a sustained modulation of synaptic efficacy. A) Schematic of anodal ( left ) and cathodal ( right ) DCS with current flow along the...current stimulation (tDCS) delivered 1day vs . 1week after cerebral ischemia in rats. Brain Res. Zimerman M, Nitsch M, Giraux P, Gerloff C, Cohen LG

Imaging transcranial direct current stimulation (tDCS) of the prefrontal cortex-correlation or causality in stimulation-mediated effects?

Science.gov (United States)

Wörsching, Jana; Padberg, Frank; Ertl-Wagner, Birgit; Kumpf, Ulrike; Kirsch, Beatrice; Keeser, Daniel

2016-10-01

Transcranial current stimulation approaches include neurophysiologically distinct non-invasive brain stimulation techniques widely applied in basic, translational and clinical research: transcranial direct current stimulation (tDCS), oscillating transcranial direct current stimulation (otDCS), transcranial alternating current stimulation (tACS) and transcranial random noise stimulation (tRNS). Prefrontal tDCS seems to be an especially promising tool for clinical practice. In order to effectively modulate relevant neural circuits, systematic research on prefrontal tDCS is needed that uses neuroimaging and neurophysiology measures to specifically target and adjust this method to physiological requirements. This review therefore analyses the various neuroimaging methods used in combination with prefrontal tDCS in healthy and psychiatric populations. First, we provide a systematic overview on applications, computational models and studies combining neuroimaging or neurophysiological measures with tDCS. Second, we categorise these studies in terms of their experimental designs and show that many studies do not vary the experimental conditions to the extent required to demonstrate specific relations between tDCS and its behavioural or neurophysiological effects. Finally, to support best-practice tDCS research we provide a methodological framework for orientation among experimental designs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Self-commutated high-voltage direct current transmission with DC circuit breakers. Backbone for the energy policy turnaround; Selbstgefuehrte Hochspannungs-Gleichstromuebertragung mit DC-Leistungsschalter. Rueckgrat fuer die Energiewende

Energy Technology Data Exchange (ETDEWEB)

Goerner, Raphael [ABB AG, Mannheim (Germany). Marketing und Vertrieb, Geschaeftsbereich Grid Systems

2013-06-01

The 'current war' between direct current and alternating current is extended by a new location. In the future, both technologies work together in order to provide a reliable power transmission in Germany and long-term in Europe. This is based on the self-guided high-voltage direct current transmission. In conjunction with direct current circuit breakers (DC circuit breaker) the power circuit breakers may help to make the transmission grids more flexible and to minimize losses.

Spermatogonial stem cell transplantation and male infertility: Current status and future directions

Directory of Open Access Journals (Sweden)

Connor M. Forbes

2018-03-01

Full Text Available Objective: To summarise the current state of research into spermatogonial stem cell (SSC therapies with a focus on future directions, as SSCs show promise as a source for preserving or initiating fertility in otherwise infertile men. Materials and methods: We performed a search for publications addressing spermatogonial stem cell transplantation in the treatment of male infertility. The search engines PubMed and Google Scholar were used from 1990 to 2017. Search terms were relevant for spermatogonial stem cell therapies. Titles of publications were screened for relevance; abstracts were read, if related and full papers were reviewed for directly pertinent original research. Results: In all, 58 papers were found to be relevant to this review, and were included in appropriate subheadings. This review discusses the various techniques that SSCs are being investigated to treat forms of male infertility. Conclusions: Evidence does not yet support clinical application of SSCs in humans. However, significant progress in the in vitro and in vivo development of SSCs, including differentiation into functional germ cells, gives reason for cautious optimism for future research. Keywords: Non-obstructive azoospermia, Fertility preservation, Onco-fertility, Male infertility, Stem cell therapy, Allograft

Transcranial Direct Current Stimulation (tDCS: A Beginner's Guide for Design and Implementation

Directory of Open Access Journals (Sweden)

Hayley Thair

2017-11-01

Full Text Available Transcranial direct current stimulation (tDCS is a popular brain stimulation method that is used to modulate cortical excitability, producing facilitatory or inhibitory effects upon a variety of behaviors. There is, however, a current lack of consensus between studies, with many results suggesting that polarity-specific effects are difficult to obtain. This article explores some of these differences and highlights the experimental parameters that may underlie their occurrence. We provide a general, practical snapshot of tDCS methodology, including what it is used for, how to use it, and considerations for designing an effective and safe experiment. Our aim is to equip researchers who are new to tDCS with the essential knowledge so that they can make informed and well-rounded decisions when designing and running successful experiments. By summarizing the varied approaches, stimulation parameters, and outcomes, this article should help inform future tDCS research in a variety of fields.

Transcranial Direct Current Stimulation (tDCS): A Beginner's Guide for Design and Implementation

Science.gov (United States)

Thair, Hayley; Holloway, Amy L.; Newport, Roger; Smith, Alastair D.

2017-01-01

Transcranial direct current stimulation (tDCS) is a popular brain stimulation method that is used to modulate cortical excitability, producing facilitatory or inhibitory effects upon a variety of behaviors. There is, however, a current lack of consensus between studies, with many results suggesting that polarity-specific effects are difficult to obtain. This article explores some of these differences and highlights the experimental parameters that may underlie their occurrence. We provide a general, practical snapshot of tDCS methodology, including what it is used for, how to use it, and considerations for designing an effective and safe experiment. Our aim is to equip researchers who are new to tDCS with the essential knowledge so that they can make informed and well-rounded decisions when designing and running successful experiments. By summarizing the varied approaches, stimulation parameters, and outcomes, this article should help inform future tDCS research in a variety of fields. PMID:29213226

Transcranial direct current stimulation (tDCS) for treatment of major depression during pregnancy: study protocol for a pilot randomized controlled trial.

Science.gov (United States)

Vigod, Simone; Dennis, Cindy-Lee; Daskalakis, Zafiris; Murphy, Kellie; Ray, Joel; Oberlander, Tim; Somerton, Sarah; Hussain-Shamsy, Neesha; Blumberger, Daniel

2014-09-18

Women with depression in pregnancy are faced with difficult treatment decisions. Untreated, antenatal depression has serious negative implications for mothers and children. While antidepressant drug treatment is likely to improve depressive symptoms, it crosses the placenta and may pose risks to the unborn child. Transcranial direct current stimulation is a focal brain stimulation treatment that improves depressive symptoms within 3 weeks of treatment by inducing changes to brain areas involved in depression, without impacting any other brain areas, and without inducing changes to heart rate, blood pressure or core body temperature. The localized nature of transcranial direct current stimulation makes it an ideal therapeutic approach for treating depression during pregnancy, although it has never previously been evaluated in this population. We describe a pilot randomized controlled trial of transcranial direct current stimulation among women with depression in pregnancy to assess the feasibility of a larger, multicentre efficacy study. Women over 18 years of age and between 14 and 32 weeks gestation can be enrolled in the study provided they meet diagnostic criteria for a major depressive episode of at least moderate severity and have been offered but refused antidepressant medication. Participants are randomized to receive active transcranial direct current stimulation or a sham condition that is administered in 15 30-minute treatments over three weeks. Women sit upright during treatment and receive obstetrical monitoring prior to, during and after each treatment session. Depressive symptoms, treatment acceptability, and pregnancy outcomes are assessed at baseline (prior to randomization), at the end of each treatment week, every four weeks post-treatment until delivery, and at 4 and 12 weeks postpartum. Transcranial direct current stimulation is a novel therapeutic option for treating depression during pregnancy. This protocol allows for assessment of the

Top-Down Effect of Direct Current Stimulation on the Nociceptive Response of Rats.

Directory of Open Access Journals (Sweden)

Luiz Fabio Dimov

Full Text Available Transcranial direct current stimulation (tDCS is an emerging, noninvasive technique of neurostimulation for treating pain. However, the mechanisms and pathways involved in its analgesic effects are poorly understood. Therefore, we investigated the effects of direct current stimulation (DCS on thermal and mechanical nociceptive thresholds and on the activation of the midbrain periaqueductal gray (PAG and the dorsal horn of the spinal cord (DHSC in rats; these central nervous system areas are associated with pain processing. Male Wistar rats underwent cathodal DCS of the motor cortex and, while still under stimulation, were evaluated using tail-flick and paw pressure nociceptive tests. Sham stimulation and naive rats were used as controls. We used a randomized design; the assays were not blinded to the experimenter. Immunoreactivity of the early growth response gene 1 (Egr-1, which is a marker of neuronal activation, was evaluated in the PAG and DHSC, and enkephalin immunoreactivity was evaluated in the DHSC. DCS did not change the thermal nociceptive threshold; however, it increased the mechanical nociceptive threshold of both hind paws compared with that of controls, characterizing a topographical effect. DCS decreased the Egr-1 labeling in the PAG and DHSC as well as the immunoreactivity of spinal enkephalin. Altogether, the data suggest that DCS disinhibits the midbrain descending analgesic pathway, consequently inhibiting spinal nociceptive neurons and causing an increase in the nociceptive threshold. This study reinforces the idea that the motor cortex participates in the neurocircuitry that is involved in analgesia and further clarifies the mechanisms of action of tDCS in pain treatment.

Cathodal Transcranial Direct Current Stimulation of the Right Wernicke's Area Improves Comprehension in Subacute Stroke Patients

Science.gov (United States)

You, Dae Sang; Kim, Dae-Yul; Chun, Min Ho; Jung, Seung Eun; Park, Sung Jong

2011-01-01

Previous studies have shown the appearance of right-sided language-related brain activity in right-handed patients after a stroke. Non-invasive brain stimulation such as transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) have been shown to modulate excitability in the brain. Moreover, rTMS and…

Guest Editorial: Flexible Operation and Control for Medium Voltage Direct-Current (MVDC) Grid

DEFF Research Database (Denmark)

Li, Yong; Guerrero, Josep M.; Siano, Pierluigi

2017-01-01

We appreciate very much the support from the IET Power Electronics editorial board for this Special Issue on ‘Flexible Operation and Control for Medium Voltage Direct-Current (MVDC) Grid’. In this final version for publication, 15 papers have been selected for this Special Issue. Three papers...... relate to the topology of MVDC converter, four papers relate to the control of MVDC converter, four papers relate to the introduction of application fields of MVDC grid, and four papers relate to the semiconductor power device and drives towards the application in the medium- and high-voltage DC grid....

Transcranial Direct Current Stimulation, Symptomatology, and Cognition in Psychosis: A Qualitative Review

Directory of Open Access Journals (Sweden)

Tina Gupta

2018-05-01

Full Text Available Schizophrenia is a chronic, debilitating condition that affects approximately 1% of the population. Individuals diagnosed with schizophrenia typically exhibit positive (e.g., hallucinations and negative symptoms (e.g., anhedonia and impairments in cognitive function. Given the limitations of antipsychotic medication and psychotherapy in fully treating psychosis symptomatology, there has been increasing interest in other interventions such as transcranial direct current stimulation (tDCS. tDCS is a non-invasive neuromodulation technique, that is safe, cost-effective, and widely accessible. Here, we discuss treatment studies that seek to improve symptoms and cognitive performance in schizophrenia using tDCS. Currently within the literature, there is support for reductions in positive symptoms such as hallucinations after receiving tDCS. Further, studies indicate that tDCS can improve cognitive functioning, which is an area of investigation that is sorely needed, as it is unclear which types of interventions may be useful in ameliorating cognitive deficits among this group. Taken together, the evidence suggests that tDCS holds promise in improving symptoms and cognition. To that end, tDCS has critical clinical implications for this population.

Efficacy of transcranial direct current stimulation (tDCS) in reducing consumption in patients with alcohol use disorders: study protocol for a randomized controlled trial.

Science.gov (United States)

Trojak, Benoit; Soudry-Faure, Agnès; Abello, Nicolas; Carpentier, Maud; Jonval, Lysiane; Allard, Coralie; Sabsevari, Foroogh; Blaise, Emilie; Ponavoy, Eddy; Bonin, Bernard; Meille, Vincent; Chauvet-Gelinier, Jean-Christophe

2016-05-17

Approximately 15 million persons in the European Union and 10 million persons in the USA are alcohol-dependent. The global burden of disease and injury attributable to alcohol is considerable: worldwide, approximately one in 25 deaths in 2004 was caused by alcohol. At the same time, alcohol use disorders remain seriously undertreated. In this context, alternative or adjunctive therapies such as brain stimulation may play a prominent role. The early results of studies using transcranial direct current stimulation found that stimulations delivered to the dorsolateral prefrontal cortex result in a significant reduction of craving and an improvement of the decision-making processes in various additive disorders. We, therefore, hypothesize that transcranial direct current stimulation can lead to a decrease in alcohol consumption in patients suffering from alcohol use disorders. We report the protocol of a randomized, double-blind, placebo-controlled, parallel-group trial, to evaluate the efficacy of transcranial direct current stimulation on alcohol reduction in patients with an alcohol use disorder. The study will be conducted in 14 centers in France and Monaco. Altogether, 340 subjects over 18 years of age and diagnosed with an alcohol use disorder will be randomized to receive five consecutive twice-daily sessions of either active or placebo transcranial direct current stimulation. One session consists in delivering a current flow continuously (anode F4; cathode F3) twice for 13 minutes, with treatments separated by a rest interval of 20 min. Efficacy will be evaluated using the change from baseline (alcohol consumption during the 4 weeks before randomization) to 24 weeks in the total alcohol consumption and number of heavy drinking days. Secondary outcome measures will include alcohol craving, clinical and biological improvements, and the effects on mood and quality of life, as well as cognitive and safety assessments, and, for smokers, an assessment of the

Influence of direct and alternating current electric fields on efficiency promotion and leaching risk alleviation of chelator assisted phytoremediation.

Science.gov (United States)

Luo, Jie; Cai, Limei; Qi, Shihua; Wu, Jian; Sophie Gu, Xiaowen

2018-03-01

Direct and alternating current electric fields with various voltages were used to improve the decontamination efficiency of chelator assisted phytoremediation for multi-metal polluted soil. The alleviation effect of electric field on leaching risk caused by chelator application during phytoremediation process was also evaluated. Biomass yield, pollutant uptake and metal leaching retardation under alternating current (AC) and direct current (DC) electric fields were compared. The biomass yield of Eucalyptus globulus under AC fields with various voltages (2, 4 and 10 V) were 3.91, 4.16 and 3.67kg, respectively, significantly higher than the chelator treatment without electric field (2.71kg). Besides growth stimulation, AC fields increased the metal concentrations of plant tissues especially in aerial parts manifested by the raised translocation factor of different metals. Direct current electric fields with low and moderate voltages increased the biomass production of the species to 3.45 and 3.12kg, respectively, while high voltage on the contrary suppressed the growth of the plants (2.66kg). Under DC fields, metal concentrations elevated obviously with increasing voltages and the metal translocation factors were similar under all voltages. Metal extraction per plant achieved the maximum value under moderate voltage due to the greatest biomass production. DC field with high voltage (10V) decreased the volume of leachate from the chelator treatment without electric field from 1224 to 56mL, while the leachate gathered from AC field treatments raised from 512 to 670mL. DC field can retard the downward movement of metals caused by chelator application more effectively relative to AC field due to the constant water flow and electroosmosis direction. Alternating current field had more promotive effect on chelator assisted phytoremediation efficiency than DC field illustrated by more metal accumulation in the species. However, with the consideration of leaching risk, DC

Transcranial Direct Current Stimulation and behavioral models of smoking addiction

Directory of Open Access Journals (Sweden)

Paige eFraser

2012-08-01

Full Text Available While few studies have applied transcranial direct current stimulation (tDCS to smoking addiction, existing work suggests that the intervention holds promise for altering the complex system by which environmental cues interact with cravings to drive behavior. Imaging and repetitive transcranial magnetic stimulation (rTMS studies suggest that increased dorsolateral prefrontal cortex (DLPFC activation and integrity may be associated with increased resistance to smoking cues. Anodal tDCS of the DLPFC, believed to boost activation, reduces cravings in response to these cues. The finding that noninvasive stimulation modifies cue induced cravings has profound implications for understanding the processes underlying addiction and relapse. TDCS can also be applied to probe mechanisms underlying and supporting nicotine addiction, as was done in a pharmacologic study that applied nicotine, tDCS, and TMS paired associative stimulation to find that stopping nicotine after chronic use induces a reduction in plasticity, causing difficulty in breaking free from association between cues and cravings. This mini-review will place studies that apply tDCS to smokers in the context of research involving the neural substrates of nicotine addiction.

Magnetic particle imaging: current developments and future directions

Directory of Open Access Journals (Sweden)

Panagiotopoulos N

2015-04-01

of different theories and technical approaches on the way to the actual implementation of the basic concept of MPI have been seen in the last few years. Research groups around the world are working on different scanner geometries, from closed bore systems to single-sided scanners, and use reconstruction methods that are either based on actual calibration measurements or on theoretical models. This review aims at giving an overview of current developments and future directions in MPI about a decade after its first appearance. Keywords: magnetic particle imaging, superparamagnetic iron oxide nanoparticles, magnetic particle spectrometer, peripheral nerve stimulation, cardiovascular interventions

Geophysical investigation of Red Devil mine using direct-current resistivity and electromagnetic induction, Red Devil, Alaska, August 2010

Science.gov (United States)

Burton, Bethany L.; Ball, Lyndsay B.

2011-01-01

Red Devil Mine, located in southwestern Alaska near the Village of Red Devil, was the state's largest producer of mercury and operated from 1933 to 1971. Throughout the lifespan of the mine, various generations of mills and retort buildings existed on both sides of Red Devil Creek, and the tailings and waste rock were deposited across the site. The mine was located on public Bureau of Land Management property, and the Bureau has begun site remediation by addressing mercury, arsenic, and antimony contamination caused by the minerals associated with the ore deposit (cinnabar, stibnite, realgar, and orpiment). In August 2010, the U.S. Geological Survey completed a geophysical survey at the site using direct-current resistivity and electromagnetic induction surface methods. Eight two-dimensional profiles and one three-dimensional grid of direct-current resistivity data as well as about 5.7 kilometers of electromagnetic induction profile data were acquired across the site. On the basis of the geophysical data and few available soil borings, there is not sufficient electrical or electromagnetic contrast to confidently distinguish between tailings, waste rock, and weathered bedrock. A water table is interpreted along the two-dimensional direct-current resistivity profiles based on correlation with monitoring well water levels and a relatively consistent decrease in resistivity typically at 2-6 meters depth. Three settling ponds used in the last few years of mine operation to capture silt and sand from a flotation ore processing technique possessed conductive values above the interpreted water level but more resistive values below the water level. The cause of the increased resistivity below the water table is unknown, but the increased resistivity may indicate that a secondary mechanism is affecting the resistivity structure under these ponds if the depth of the ponds is expected to extend below the water level. The electromagnetic induction data clearly identified the

Polarity-Specific Transcranial Direct Current Stimulation Disrupts Auditory Pitch Learning

Directory of Open Access Journals (Sweden)

Reiko eMatsushita

2015-05-01

Full Text Available Transcranial direct current stimulation (tDCS is attracting increasing interest because of its potential for therapeutic use. While its effects have been investigated mainly with motor and visual tasks, less is known in the auditory domain. Past tDCS studies with auditory tasks demonstrated various behavioural outcomes, possibly due to differences in stimulation parameters or task measurements used in each study. Further research using well-validated tasks are therefore required for clarification of behavioural effects of tDCS on the auditory system. Here, we took advantage of findings from a prior functional magnetic resonance imaging study, which demonstrated that the right auditory cortex is modulated during fine-grained pitch learning of microtonal melodic patterns. Targeting the right auditory cortex with tDCS using this same task thus allowed us to test the hypothesis that this region is causally involved in pitch learning. Participants in the current study were trained for three days while we measured pitch discrimination thresholds using microtonal melodies on each day using a psychophysical staircase procedure. We administered anodal, cathodal, or sham tDCS to three groups of participants over the right auditory cortex on the second day of training during performance of the task. Both the sham and the cathodal groups showed the expected significant learning effect (decreased pitch threshold over the three days of training; in contrast we observed a blocking effect of anodal tDCS on auditory pitch learning, such that this group showed no significant change in thresholds over the three days. The results support a causal role for the right auditory cortex in pitch discrimination learning.

VoLTE performance in railway scenarios

DEFF Research Database (Denmark)

Sniady, Aleksander; Sønderskov, Morten; Soler, José

2015-01-01

GSM-Railways (GSM-R) is the current standard for railway voice and data communication. GSM-R provides railway specific voice services, such as Railway Emergency Call (REC). GSM-R provides also the European Train Control System (ETCS), which offers in-cab signaling and Automatic Train Protection...... (ATP). Despite these features and services, GSM-R has various major shortcomings. Therefore, alternative technologies are considered to replace GSM-R and become the next generation railway mobile communication network. 3GPP Long Term Evolution (LTE) is a likely candidate for GSM-R replacement. LTE...... is more efficient, flexible and offers much higher capacity, which allows the railway network to provide new communication-based applications for railways. Most of the research on LTE in railways has been focused on data-based railway applications (ETCS signaling and other). Nevertheless, voice...

VoLTE Performance in Railway Scenarios

DEFF Research Database (Denmark)

Sniady, Aleksander; Sønderskov, Morten; Soler, José

2015-01-01

GSM-Railways (GSM-R) is the current standard for railway voice and data communication. GSM-R provides railway specific voice services, such as Railway Emergency Call (REC). GSM-R provides also the European Train Control System (ETCS), which offers in-cab signaling and Automatic Train Protection...... (ATP). Despite these features and services, GSM-R has various major shortcomings. Therefore, alternative technologies are considered to replace GSM-R and become the next generation railway mobile communication network. 3GPP Long Term Evolution (LTE) is a likely candidate for GSM-R replacement. LTE...... is more efficient, flexible and offers much higher capacity, which allows the railway network to provide new communication-based applications for railways. Most of the research on LTE in railways has been focused on data-based railway applications (ETCS signaling and other). Nevertheless, voice...

Acute changes in motor cortical excitability during slow oscillatory and constant anodal transcranial direct current stimulation

DEFF Research Database (Denmark)

Bergmann, Til Ole; Groppa, Sergiu; Seeger, Markus

2009-01-01

Transcranial oscillatory current stimulation has recently emerged as a noninvasive technique that can interact with ongoing endogenous rhythms of the human brain. Yet, there is still little knowledge on how time-varied exogenous currents acutely modulate cortical excitability. In ten healthy...... individuals we used on-line single-pulse transcranial magnetic stimulation (TMS) to search for systematic shifts in corticospinal excitability during anodal sleeplike 0.8-Hz slow oscillatory transcranial direct current stimulation (so-tDCS). In separate sessions, we repeatedly applied 30-s trials (two blocks...... at 20 min) of either anodal so-tDCS or constant tDCS (c-tDCS) to the primary motor hand area during quiet wakefulness. Simultaneously and time-locked to different phase angles of the slow oscillation, motor-evoked potentials (MEPs) as an index of corticospinal excitability were obtained...

CURRENT - DIRECTION and Other Data from UNKNOWN From World-Wide Distribution from 19850101 to 19851231 (NODC Accession 8900039)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set is a backup of the 1985 tropical pacific subsurface (XBT/ MBT) thermal data. The current direction, salinity and temperature for Tropical Ocean Global...

Variable Frequency Operations of an Offshore Wind Power Plant with HVDC-VSC: Preprint

Energy Technology Data Exchange (ETDEWEB)

Gevorgian, V.; Singh, M.; Muljadi, E.

2011-12-01

In this paper, a constant Volt/Hz operation applied to the Type 1 wind turbine generator. Various control aspects of Type 1 generators at the plant level and at the turbine level will be investigated. Based on DOE study, wind power generation may reach 330 GW by 2030 at the level of penetration of 20% of the total energy production. From this amount of wind power, 54 GW of wind power will be generated at offshore wind power plants. The deployment of offshore wind power plants requires power transmission from the plant to the load center inland. Since this power transmission requires submarine cable, there is a need to use High-Voltage Direct Current (HVDC) transmission. Otherwise, if the power is transmitted via alternating current, the reactive power generated by the cable capacitance may cause an excessive over voltage in the middle of the transmission distance which requires unnecessary oversized cable voltage breakdown capability. The use of HVDC is usually required for transmission distance longer than 50 kilometers of submarine cables to be economical. The use of HVDC brings another advantage; it is capable of operating at variable frequency. The inland substation will be operated to 60 Hz synched with the grid, the offshore substation can be operated at variable frequency, thus allowing the wind power plant to be operated at constant Volt/Hz. In this paper, a constant Volt/Hz operation applied to the Type 1 wind turbine generator. Various control aspects of Type 1 generators at the plant level and at the turbine level will be investigated.

Application possibility of the direct current conduction method for nondestructive crack measurement

International Nuclear Information System (INIS)

Riedl, R.

1982-01-01

An important value to determine the danger of cracks is the determination of crack depths. The crack depth can be determined quite accurate by means of the direct current conduction method, if one holds onto certain rules. Often complicated experimental set-ups are applied. However, portable commercial devices can be obtained that can be used for partial fluxation, that yield good results. By means of two examples: crack conduction samples in which the built-up of a constant-cracking is persued up to a certain depth, as well as the persuasion of an continuing crack in a bearing cylinder, shall be demonstrated that is very well possible to record accurate profiles with commercial devices and to avoid expensive measurement devices. (orig.) [de

Identifying therapeutic targets in gastric cancer: the current status and future direction

Science.gov (United States)

Yu, Beiqin; Xie, Jingwu

2016-01-01

Gastric cancer is the third leading cause of cancer-related death worldwide. Our basic understanding of gastric cancer biology falls behind that of many other cancer types. Current standard treatment options for gastric cancer have not changed for the last 20 years. Thus, there is an urgent need to establish novel strategies to treat this deadly cancer. Successful clinical trials with Gleevec in CML and gastrointestinal stromal tumors have set up an example for targeted therapy of cancer. In this review, we will summarize major progress in classification, therapeutic options of gastric cancer. We will also discuss molecular mechanisms for drug resistance in gastric cancer. In addition, we will attempt to propose potential future directions in gastric cancer biology and drug targets. PMID:26373844

In vitro effects of direct current electric fields on adipose-derived stromal cells.

Science.gov (United States)

Hammerick, Kyle E; Longaker, Michael T; Prinz, Fritz B

2010-06-18

Endogenous electric fields play an important role in embryogenesis, regeneration, and wound repair and previous studies have shown that many populations of cells, leukocytes, fibroblasts, epithelial cells, and endothelial cells, exhibit directed migration in response to electric fields. As regenerative therapies continue to explore ways to control mesenchymal progenitor cells to recreate desirable tissues, it is increasingly necessary to characterize the vast nature of biological responses imposed by physical phenomena. Murine adipose-derived stromal cells (mASCs) migrated toward the cathode in direct current (DC) fields of physiologic strength and show a dose dependence of migration rate to stronger fields. Electric fields also caused mASCs to orient perpendicularly to the field vector and elicited a transient increase in cytosolic calcium. Additionally, their galvanotactic response appears to share classic chemotactic signaling pathways that are involved in the migration of other cell types. Galvanotaxis is one predominant result of electric fields on mASCs and it may be exploited to engineer adult stem cell concentrations and locations within implanted grafts or toward sites of wound repair. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Transcranial Direct Current Stimulation and Power Spectral Parameters: a tDCS/EEG co-registration study

Directory of Open Access Journals (Sweden)

Anna Lisa Mangia

2014-08-01

Full Text Available Transcranial direct current stimulation (tDCS delivers low electric currents to the brain through the scalp. Constant electric currents induce shifts in neuronal membrane excitability, resulting in secondary changes in cortical activity. Concomitant electroencephalography (EEG monitoring during tDCS can provide valuable information on the tDCS mechanisms of action. This study examined the effects of anodal tDCS on spontaneous cortical activity in a resting brain to disclose possible modulation of spontaneous oscillatory brain activity. EEG activity was measured in ten healthy subjects during and after a session of anodal stimulation of the postero-parietal cortex to detect the tDCS-induced alterations. Changes in the theta, alpha, beta and gamma power bands were investigated. Three main findings emerged: 1 an increase in theta band activity during the first minutes of stimulation; 2 an increase in alpha and beta power during and after stimulation; 3 a widespread activation in several brain regions.

Evidence of transcranial direct current stimulation-generated electric fields at subthalamic level in human brain in vivo.

Science.gov (United States)

Chhatbar, Pratik Y; Kautz, Steven A; Takacs, Istvan; Rowland, Nathan C; Revuelta, Gonzalo J; George, Mark S; Bikson, Marom; Feng, Wuwei

2018-03-13

Transcranial direct current stimulation (tDCS) is a promising brain modulation technique for several disease conditions. With this technique, some portion of the current penetrates through the scalp to the cortex and modulates cortical excitability, but a recent human cadaver study questions the amount. This insufficient intracerebral penetration of currents may partially explain the inconsistent and mixed results in tDCS studies to date. Experimental validation of a transcranial alternating current stimulation-generated electric field (EF) in vivo has been performed on the cortical (using electrocorticography, ECoG, electrodes), subcortical (using stereo electroencephalography, SEEG, electrodes) and deeper thalamic/subthalamic levels (using DBS electrodes). However, tDCS-generated EF measurements have never been attempted. We aimed to demonstrate that tDCS generates biologically relevant EF as deep as the subthalamic level in vivo. Patients with movement disorders who have implanted deep brain stimulation (DBS) electrodes serve as a natural experimental model for thalamic/subthalamic recordings of tDCS-generated EF. We measured voltage changes from DBS electrodes and body resistance from tDCS electrodes in three subjects while applying direct current to the scalp at 2 mA and 4 mA over two tDCS montages. Voltage changes at the level of deep nuclei changed proportionally with the level of applied current and varied with different tDCS montages. Our findings suggest that scalp-applied tDCS generates biologically relevant EF. Incorporation of these experimental results may improve finite element analysis (FEA)-based models. Copyright © 2018 Elsevier Inc. All rights reserved.

Current direction, temperature, salinity, and taxonomic code data from moored current meter casts in the Gulf of Mexico during the Brine Disposal project, 1979-08-18 to 1981-01-21 (NODC Accession 8100502)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature, salinity, current direction, and taxonomic data were collected using moored current meter casts in the Gulf of Mexico from August 18, 1979 to January...

Adaptive Modulation for DFIG and STATCOM With High-Voltage Direct Current Transmission.

Science.gov (United States)

Tang, Yufei; He, Haibo; Ni, Zhen; Wen, Jinyu; Huang, Tingwen

2016-08-01

This paper develops an adaptive modulation approach for power system control based on the approximate/adaptive dynamic programming method, namely, the goal representation heuristic dynamic programming (GrHDP). In particular, we focus on the fault recovery problem of a doubly fed induction generator (DFIG)-based wind farm and a static synchronous compensator (STATCOM) with high-voltage direct current (HVDC) transmission. In this design, the online GrHDP-based controller provides three adaptive supplementary control signals to the DFIG controller, STATCOM controller, and HVDC rectifier controller, respectively. The mechanism is to observe the system states and their derivatives and then provides supplementary control to the plant according to the utility function. With the GrHDP design, the controller can adaptively develop an internal goal representation signal according to the observed power system states, therefore, to achieve more effective learning and modulating. Our control approach is validated on a wind power integrated benchmark system with two areas connected by HVDC transmission lines. Compared with the classical direct HDP and proportional integral control, our GrHDP approach demonstrates the improved transient stability under system faults. Moreover, experiments under different system operating conditions with signal transmission delays are also carried out to further verify the effectiveness and robustness of the proposed approach.

Spatial and polarity precision of concentric high-definition transcranial direct current stimulation (HD-tDCS)

Science.gov (United States)

Alam, Mahtab; Truong, Dennis Q.; Khadka, Niranjan; Bikson, Marom

2016-06-01

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique that applies low amplitude current via electrodes placed on the scalp. Rather than directly eliciting a neuronal response, tDCS is believed to modulate excitability—enhancing or suppressing neuronal activity in regions of the brain depending on the polarity of stimulation. The specificity of tDCS to any therapeutic application derives in part from how electrode configuration determines the brain regions that are stimulated. Conventional tDCS uses two relatively large pads (>25 cm2) whereas high-definition tDCS (HD-tDCS) uses arrays of smaller electrodes to enhance brain targeting. The 4  ×  1 concentric ring HD-tDCS (one center electrode surrounded by four returns) has been explored in application where focal targeting of cortex is desired. Here, we considered optimization of concentric ring HD-tDCS for targeting: the role of electrodes in the ring and the ring’s diameter. Finite element models predicted cortical electric field generated during tDCS. High resolution MRIs were segmented into seven tissue/material masks of varying conductivities. Computer aided design (CAD) model of electrodes, gel, and sponge pads were incorporated into the segmentation. Volume meshes were generated and the Laplace equation (\

Parameter Improved Particle Swarm Optimization Based Direct-Current Vector Control Strategy for Solar PV System

Directory of Open Access Journals (Sweden)

NAMMALVAR, P.

2018-02-01

Full Text Available This paper projects Parameter Improved Particle Swarm Optimization (PIPSO based direct current vector control technology for the integration of photovoltaic array in an AC micro-grid to enhance the system performance and stability. A photovoltaic system incorporated with AC micro-grid is taken as the pursuit of research study. The test system features two power converters namely, PV side converter which consists of DC-DC boost converter with Perturbation and Observe (P&O MPPT control to reap most extreme power from the PV array, and grid side converter which consists of Grid Side-Voltage Source Converter (GS-VSC with proposed direct current vector control strategy. The gain of the proposed controller is chosen from a set of three values obtained using apriori test and tuned through the PIPSO algorithm so that the Integral of Time multiplied Absolute Error (ITAE between the actual and the desired DC link capacitor voltage reaches a minimum and allows the system to extract maximum power from PV system, whereas the existing d-q control strategy is found to perform slowly to control the DC link voltage under varying solar insolation and load fluctuations. From simulation results, it is evident that the proposed optimal control technique provides robust control and improved efficiency.

Effects of transcranial direct current stimulation on motor learning in healthy individuals: a systematic review

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Águida Foerster

Full Text Available Introduction Transcranial direct current stimulation (tDCS has been used to modify cortical excitability and promote motor learning. Objective To systematically review published data to investigate the effects of transcranial direct current stimulation on motor learning in healthy individuals. Methods Randomized or quasi-randomized studies that evaluated the tDCS effects on motor learning were included and the risk of bias was examined by Cochrane Collaboration’s tool. The following electronic databases were used: PubMed, Scopus, Web of Science, LILACS, CINAHL with no language restriction. Results It was found 160 studies; after reading the title and abstract, 17 of those were selected, but just 4 were included. All studies involved healthy, right-handed adults. All studies assessed motor learning by the Jebsen Taylor Test or by the Serial Finger Tapping Task (SFTT. Almost all studies were randomized and all were blinding for participants. Some studies presented differences at SFTT protocol. Conclusion The result is insufficient to draw conclusions if tDCS influences the motor learning. Furthermore, there was significant heterogeneity of the stimulation parameters used. Further researches are needed to investigate the parameters that are more important for motor learning improvement and measure whether the effects are long-lasting or limited in time.

Direct imaging of enhanced current collection on grain boundaries of Cu(In,Ga)Se{sub 2} solar cells

Energy Technology Data Exchange (ETDEWEB)

Kim, JunHo, E-mail: jhk@incheon.ac.kr [Department of Physics, Incheon National University, Incheon 406-772 (Korea, Republic of); National Center for Photovoltaics, National Renewable Energy Laboratory (NREL), Golden, Colorado 80401 (United States); Kim, SeongYeon [Department of Physics, Incheon National University, Incheon 406-772 (Korea, Republic of); Jiang, Chun-Sheng; Ramanathan, Kannan; Al-Jassim, Mowafak M. [National Center for Photovoltaics, National Renewable Energy Laboratory (NREL), Golden, Colorado 80401 (United States)

2014-02-10

We report on direct imaging of current collection by performing conductive atomic force microscopy (C-AFM) measurement on a complete Cu(In,Ga)Se{sub 2} solar cell. The localized current was imaged by milling away the top conductive layer of the device by repeated C-AFM scans. The result exhibits enhanced photocurrent collection on grain boundaries (GBs) of CIGS films, consistent with the argument for electric-field-assisted carrier collection on the GBs.

Edge effects in four-point direct current potential drop measurements on metal plates

International Nuclear Information System (INIS)

Lu, Y; Bowler, N; Bowler, J R; Huang, Y

2009-01-01

Four-point direct current potential drop (DCPD) measurements are commonly used to measure the conductivity (or resistivity) of semiconductors and ferrous or non-ferrous metals. The measured electrical potential difference is often interpreted in terms of analytic expressions developed for large plates that are either 'thin' or 'thick' relative to the probe length. It is well known that the presence of the back surface of a plate leads to a solution expressed in terms of an infinite series representing the current source and its images. This approach can be generalized to account for multiple surfaces in order to obtain a solution for a finite plate, but convergence of the series is poor when the plate dimensions are similar to or smaller than the separation of the current injection and extraction points. Here, Fourier series representations of the infinite sums are obtained. It is shown that the Fourier series converge with many fewer terms than the series obtained from image theory, for plates with dimensions similar to or smaller than the separation of the current injection and extraction points. Comparing calculated results for the potential drop obtained by a four-point probe centred on finite plates of varying dimension, with those for a probe in contact with a large (laterally infinite) plate, estimates are given of the uncertainty due to edge effects in measurements on small plates interpreted using analytic formulae developed for large plates. It is also shown that these uncertainties due to edge effects are reduced, for a given plate size, if the probe pick-up points are moved closer to the current injection points, rather than adopting the common arrangement in which the four probe points are equally spaced. Calculated values of DCPD are compared with experimental data taken on aluminium and spring-steel plates of various sizes and excellent agreement is obtained.

Edge effects in four-point direct current potential drop measurements on metal plates

Science.gov (United States)

Lu, Y.; Bowler, N.; Bowler, J. R.; Huang, Y.

2009-07-01

Four-point direct current potential drop (DCPD) measurements are commonly used to measure the conductivity (or resistivity) of semiconductors and ferrous or non-ferrous metals. The measured electrical potential difference is often interpreted in terms of analytic expressions developed for large plates that are either 'thin' or 'thick' relative to the probe length. It is well known that the presence of the back surface of a plate leads to a solution expressed in terms of an infinite series representing the current source and its images. This approach can be generalized to account for multiple surfaces in order to obtain a solution for a finite plate, but convergence of the series is poor when the plate dimensions are similar to or smaller than the separation of the current injection and extraction points. Here, Fourier series representations of the infinite sums are obtained. It is shown that the Fourier series converge with many fewer terms than the series obtained from image theory, for plates with dimensions similar to or smaller than the separation of the current injection and extraction points. Comparing calculated results for the potential drop obtained by a four-point probe centred on finite plates of varying dimension, with those for a probe in contact with a large (laterally infinite) plate, estimates are given of the uncertainty due to edge effects in measurements on small plates interpreted using analytic formulae developed for large plates. It is also shown that these uncertainties due to edge effects are reduced, for a given plate size, if the probe pick-up points are moved closer to the current injection points, rather than adopting the common arrangement in which the four probe points are equally spaced. Calculated values of DCPD are compared with experimental data taken on aluminium and spring-steel plates of various sizes and excellent agreement is obtained.

ENHANCING THE OPERATIONAL EFFICIENCY OF DIRECT CURRENT DRIVE BASED ON USE OF SUPERCONDENSER POWER STORAGE UNITS

Directory of Open Access Journals (Sweden)

А. M. Mukha

2017-10-01

Full Text Available Purpose.The scientific work is intended to analyse the expansion of the load range and the implementation of regeneration braking (RB of the direct current drive by using the supercondenser power storage units. Methodology.To solve the problem, we use the methods of the electric drive theory, impulse electronics and the method of calculation of transient electromagnetic processes in linear electric circuits in the presence of super-condensers therein. Findings.The stiffness of the mechanical and electromechanical characteristics of a series motor is significantly increased, which makes it possible to use a DC drive under load, much smaller than 15…20% of the nominal one. Numerical calculations of the operation process of the supercondenser power storage unit were fulfilled with a sharp decrease in the load of a traction electric motor of a direct current electric locomotive. The possibility of RB of the direct current drive with the series motor is substantiated. The equations of the process of charging and discharging of super-condenser storage unit in RB mode are solved. The authors examined the effect of capacitance on the nature of maintaining the excitation current of an electric motor in the mode of small loads.Originality.The paper developed theoretical approaches for the transformation of soft (mechanical and electromechanical characteristics into hard ones of DC series motors. For the first time a new, combined method of the series motor RB is proposed and substantiated. Further development obtained the methods for evaluating the storage unit parameters, taking into account the criteria for reliable parallel operation of super-condensers with an electric motor field. Practical value.The proposed and substantiated transformation of soft characteristics into stiff ones allows us to use general-purpose electric drives with series motors and at low loads, and in traction electric drives - to reduce the intensity of electric stockwheel

Spectrochemical determination of tantalum in plutonium metal using direct current plasma emission spectrometry

International Nuclear Information System (INIS)

Fadeff, S.K.; Morris, W.F.

1983-01-01

Tantalum is determined by direct current plasma spectrometry after separation of plutonium from solution as PuF 3 . After centrifugation of the PuF 3 precipitate, a low level of plutonium remains in solution in sufficient quantity to cause spectral interferences. It is necessary to determine the plutonium by dc plasma spectrometry and apply a correction to determine low tantalum concentrations with good accuracy and precision. Tantalum can be determined down to 0.4 ppM in solution with a relative standard deviation of 10 percent. Better precision can be achieved at higher concentrations. The procedure is simple and convenient for glovebox work. 5 references, 1 figure, 1 table

Motor unit recruitment for dynamic tasks: current understanding and future directions.

Science.gov (United States)

Hodson-Tole, Emma F; Wakeling, James M

2009-01-01

Skeletal muscle contains many muscle fibres that are functionally grouped into motor units. For any motor task there are many possible combinations of motor units that could be recruited and it has been proposed that a simple rule, the 'size principle', governs the selection of motor units recruited for different contractions. Motor units can be characterised by their different contractile, energetic and fatigue properties and it is important that the selection of motor units recruited for given movements allows units with the appropriate properties to be activated. Here we review what is currently understood about motor unit recruitment patterns, and assess how different recruitment patterns are more or less appropriate for different movement tasks. During natural movements the motor unit recruitment patterns vary (not always holding to the size principle) and it is proposed that motor unit recruitment is likely related to the mechanical function of the muscles. Many factors such as mechanics, sensory feedback, and central control influence recruitment patterns and consequently an integrative approach (rather than reductionist) is required to understand how recruitment is controlled during different movement tasks. Currently, the best way to achieve this is through in vivo studies that relate recruitment to mechanics and behaviour. Various methods for determining motor unit recruitment patterns are discussed, in particular the recent wavelet-analysis approaches that have allowed motor unit recruitment to be assessed during natural movements. Directions for future studies into motor recruitment within and between functional task groups and muscle compartments are suggested.

Relationship of herpes simplex encephalitis and transcranial direct current stimulation--a case report.

Science.gov (United States)

Yang, Yuanbin; Xiao, Juan; Song, Haiqing; Wang, Ralph; Hussain, Mohammed; Song, Weiqun

2015-04-01

We report a rare case of relapsing herpes simplex encephalitis in a-37-year-old patient which was previously confirmed by positive polymerase chain reaction, herpes simplex virus (HSV) type1 IgG antibodies in cerebrospinal fluid and characterized on MRI. During the first admission, he was treated with continuous acyclovir treatment for one month with clinical improvement except for residual aphasia, for which he received a course of outpatient transcranial direct current stimulation (tDCS). A constant current of 1.2 mA was applied for 20 min twice daily. After the 4th day the patient was found to be irritable and uncooperative by staff and family members. A subsequent MRI showed significant deterioration of the lesion on comparison to the first MRI which led to discontinuation of tDCS.The relatively rapid exacerbation of HSV in only a few days is unusual. Our aim is to discuss if tDCS is related to HSV relapse and in doing so highlight possible mechanisms. Copyright © 2015. Published by Elsevier B.V.

The decolouration of methyl orange using aluminum foam, ultrasound and direct electric current

Science.gov (United States)

Liu, C. M.; Huang, X. Y.; Zhang, H. Y.; Dai, J. D.; Ning, C. C.

2018-01-01

The decolouration of methyl orange (MO) using aluminum (Al) foam, ultrasound and direct electric current (DC) is investigated. The decolouration rate (DR) of MO using only Al foam is low because there is a passivation oxide layer on the Al foam surface. Due to the low utilization of ultrasound in MO water solution medium, the DR of MO using only ultrasonic irradiation is also poor. The DR of MO is greatly increased when Al foam, ultrasonic irradiation and DC are used together. There is good synergistic effect between Al foam, ultrasound and DC in decolouration of MO. This enhancement of DR may be related to the cavitation, cleaning of Al foam surface and water electrolysis. Due to the surface charge on wire carrying stationary current, Al foam with DC acts like a serious anodes and cathodes and makes water electrolysis giving hydrogen gas to cleavage azo bond. The DC applied on Al foam is beneficial for reductive decolouration of MO. Our results show that DC is a new way for the reductive decolouration MO in water.

High-voltage direct current (HVDC) transmission - a key technology for our power supply

International Nuclear Information System (INIS)

Dorn, J.

2016-01-01

The phasing-out of nuclear power in some countries and the aspirations of reducing carbon dioxide emissions have far-reaching implications for electric power generation in Europe. In the future, renewable electricity generation will account for a considerable share of the energy mix, but this type of production is often far from the load centers. In Germany, for example, large quantities of wind energy are already generated in the north and in the North Sea, but large load centers are located several hundred kilometers south of there. This requires an expansion of the transmission network with innovative solutions. High-voltage direct-current (HVDC) transmission plays an important role, since it brings a number of advantages over conventional AC technology and makes certain requirements feasible, for example Cable transmission over longer distances. The lecture presents the advantages of HVDC, the semiconductors used as well as the basic functions and typical performance of the used converter topopologies. The plant configurations and main components are illustrated using current projects. (rössner) [de

Current direction, temperature, zooplankton, phytoplankton, and other data from moored current meter casts in the Gulf of Mexico during the Brine Disposal project, 1980-07-15 to 1981-03-20 (NODC Accession 8100610)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, temperature, salinity, and other data were collected using moored current meter casts in the Gulf of Mexico from July 15, 1980 to March 20, 1981....

Enhancing transcranial direct current stimulation via motor imagery and kinesthetic illusion: crossing internal and external tools.

Science.gov (United States)

Bodranghien, Florian; Manto, Mario; Lebon, Florent

2016-06-01

Transcranial direct current stimulation is a safe technique which is now part of the therapeutic armamentarium for the neuromodulation of motor functions and cognitive operations. It is currently considered that tDCS is an intervention that might promote functional recovery after a lesion in the central nervous system, thus reducing long-term disability and associated socio-economic burden. A recent study shows that kinesthetic illusion and motor imagery prolong the effects of tDCS on corticospinal excitability, overcoming one of the limitations of this intervention. Because changes in excitability anticipate changes in structural plasticity in the CNS, this interesting multi-modal approach might very soon find applications in neurorehabilitation.

3-D direct current resistivity anisotropic modelling by goal-oriented adaptive finite element methods

Science.gov (United States)

Ren, Zhengyong; Qiu, Lewen; Tang, Jingtian; Wu, Xiaoping; Xiao, Xiao; Zhou, Zilong

2018-01-01

Although accurate numerical solvers for 3-D direct current (DC) isotropic resistivity models are current available even for complicated models with topography, reliable numerical solvers for the anisotropic case are still an open question. This study aims to develop a novel and optimal numerical solver for accurately calculating the DC potentials for complicated models with arbitrary anisotropic conductivity structures in the Earth. First, a secondary potential boundary value problem is derived by considering the topography and the anisotropic conductivity. Then, two a posteriori error estimators with one using the gradient-recovery technique and one measuring the discontinuity of the normal component of current density are developed for the anisotropic cases. Combing the goal-oriented and non-goal-oriented mesh refinements and these two error estimators, four different solving strategies are developed for complicated DC anisotropic forward modelling problems. A synthetic anisotropic two-layer model with analytic solutions verified the accuracy of our algorithms. A half-space model with a buried anisotropic cube and a mountain-valley model are adopted to test the convergence rates of these four solving strategies. We found that the error estimator based on the discontinuity of current density shows better performance than the gradient-recovery based a posteriori error estimator for anisotropic models with conductivity contrasts. Both error estimators working together with goal-oriented concepts can offer optimal mesh density distributions and highly accurate solutions.

Transcranial Direct Current Stimulation in Tinnitus Patients: A Systemic Review and Meta-Analysis

Directory of Open Access Journals (Sweden)

Jae-Jin Song

2012-01-01

Full Text Available Although transcranial direct current stimulation (tDCS has already been used to manage tinnitus patients, paucity of reports and variations in protocols preclude a comprehensive understanding. Hence, we conducted a meta-analysis based on systemic review to assess effectiveness of tDCS in tinnitus management and to compare stimulation parameters. PubMed was searched for tDCS studies in tinnitus. For randomized controlled trials (RCTs, a meta-analysis was performed. A total of 17 studies were identified and 6 of them were included in the systemic review and 2 RCTs were included in the meta-analysis. Overall 39.5% responded to active tDCS with a mean tinnitus intensity reduction of 13.5%. Additionally, left temporal area (LTA and bifrontal tDCS indicated comparable results. Active tDCS was found to be more effective than sham tDCS for tinnitus intensity reduction (Hedges' g=.77, 95% confidence interval 0.23–1.31. The efficacy of tDCS in tinnitus could not be fully confirmed by the current study because of the limited number of studies, but all studies included in the current systemic review and meta-analysis demonstrated significant tinnitus intensity improvement. Therefore, tDCS may be a promising tool for tinnitus management. Future RCTs in a large series regarding the efficacy as well as the comparison between LTA- and bifrontal tDCS are recommended.

[Study on the method for the determination of trace boron, molybdenum, silver, tin and lead in geochemical samples by direct current arc full spectrum direct reading atomic emission spectroscopy (DC-Arc-AES)].

Science.gov (United States)

Hao, Zhi-hong; Yao, Jian-zhen; Tang, Rui-ling; Zhang, Xue-mei; Li, Wen-ge; Zhang, Qin

2015-02-01

The method for the determmation of trace boron, molybdenum, silver, tin and lead in geochemical samples by direct current are full spectrum direct reading atomic emission spectroscopy (DC-Arc-AES) was established. Direct current are full spectrum direct reading atomic emission spectrometer with a large area of solid-state detectors has functions of full spectrum direct reading and real-time background correction. The new electrodes and new buffer recipe were proposed in this paper, and have applied for national patent. Suitable analytical line pairs, back ground correcting points of elements and the internal standard method were selected, and Ge was used as internal standard. Multistage currents were selected in the research on current program, and each current set different holding time to ensure that each element has a good signal to noise ratio. Continuous rising current mode selected can effectively eliminate the splash of the sample. Argon as shielding gas can eliminate CN band generating and reduce spectral background, also plays a role in stabilizing the are, and argon flow 3.5 L x min(-1) was selected. Evaporation curve of each element was made, and it was concluded that the evaporation behavior of each element is consistent, and combined with the effects of different spectrographic times on the intensity and background, the spectrographic time of 35s was selected. In this paper, national standards substances were selected as a standard series, and the standard series includes different nature and different content of standard substances which meet the determination of trace boron, molybdenum, silver, tin and lead in geochemical samples. In the optimum experimental conditions, the detection limits for B, Mo, Ag, Sn and Pb are 1.1, 0.09, 0.01, 0.41, and 0.56 microg x g(-1) respectively, and the precisions (RSD, n=12) for B, Mo, Ag, Sn and Pb are 4.57%-7.63%, 5.14%-7.75%, 5.48%-12.30%, 3.97%-10.46%, and 4.26%-9.21% respectively. The analytical accuracy was

Current direction, chemical, benthic organisms, and wind wave spectra data from moored current meter casts and other instruments in the Gulf of Mexico as part of the Brine Disposal project, 1977-10-14 to 1979-08-24 (NODC Accession 7900335)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, chemical, benthic organisms, and wind direction data were collected using moored current meter casts and other instruments in the Gulf of Mexico...

Blood Stage Plasmodium falciparum Exhibits Biological Responses to Direct Current Electric Fields.

Directory of Open Access Journals (Sweden)

Lorena M Coronado

Full Text Available The development of resistance to insecticides by the vector of malaria and the increasingly faster appearance of resistance to antimalarial drugs by the parasite can dangerously hamper efforts to control and eradicate the disease. Alternative ways to treat this disease are urgently needed. Here we evaluate the in vitro effect of direct current (DC capacitive coupling electrical stimulation on the biology and viability of Plasmodium falciparum. We designed a system that exposes infected erythrocytes to different capacitively coupled electric fields in order to evaluate their effect on P. falciparum. The effect on growth of the parasite, replication of DNA, mitochondrial membrane potential and level of reactive oxygen species after exposure to electric fields demonstrate that the parasite is biologically able to respond to stimuli from DC electric fields involving calcium signaling pathways.

Electrophysiological and Behavioral Effects of Combined Transcranial Direct Current Stimulation and Alcohol Approach Bias Retraining in Hazardous Drinkers

NARCIS (Netherlands)

den Uyl, T.E.; Gladwin, T.E.; Wiers, R.W.

2016-01-01

BACKGROUND: Cognitive bias modification (CBM) can be used to retrain automatic approach tendencies for alcohol. We investigated whether changing cortical excitability with transcranial direct current stimulation (tDCS) could enhance CBM effects in hazardous drinkers. We also studied the underlying

Axial mercury segregation in direct current operated low-pressure argon-mercury gas discharge: Part II. Model

International Nuclear Information System (INIS)

Gielen, John W A M; Groot, Simon de; Dijk, Jan van; Mullen, Joost J A M van der

2004-01-01

In a previous paper we had presented experimental results on mercury segregation due to cataphoresis in direct current operated low-pressure argon-mercury gas discharges. In this paper, we present our model to describe cataphoretic segregation in argon (or another noble gas)-mercury discharges. The model is based on the balance equations for mass and momentum and includes electrophoresis effects of electrons on mercury. Good agreement is found between the experimental results and model calculations. The model confirms our experimental observation that the mercury vapour pressure gradient depends on the local mercury vapour pressure. Furthermore, the model predicts the reversal of the direction of the transport of mercury under certain conditions (the phenomenon known as retrograde cataphoresis)

Effect of Transcranial Direct Current Stimulation in Patients With Tinnitus: A Meta-Analysis and Systematic Review.

Science.gov (United States)

Wang, Tang-Chuan; Tyler, Richard S; Chang, Ta-Yuan; Chen, Jui-Cheng; Lin, Chia-Der; Chung, Hsiung-Kwang; Tsou, Yung-An

2018-02-01

Subjective tinnitus is a phantom sensation experienced without any external source of sound that profoundly impacts the quality of life. Some investigations have claimed that transcranial direct current stimulation (tDCS) reduces tinnitus, but studies on tDCS have demonstrated variable results. This meta-analysis aimed to examine the effect of tDCS on patients with tinnitus. We searched for articles published through January 5, 2016, in Medline, Cochrane, EMBASE, and Google Scholar using the following keywords: tinnitus, transcranial direct current stimulation, and tDCS. The study outcomes were change in magnitude estimates of loudness (loudness), tinnitus-related distress (distress), and Tinnitus Handicap Inventory (THI). Pooled results demonstrated that tDCS did not have a beneficial effect on loudness (pooled standardized difference in means = 0.674, 95% CI, -0.089 to 1.437, P = .083). Further, the pooled results demonstrated a greater reduction in distress for the tDCS group (pooled standardized difference in means = 0.634, 95% CI, 0.021-1.247, P = .043). We conclude that the pooled results demonstrated a greater reduction in distress for groups treated with tDCS as compared with those administered a sham treatment.

Current direction, temperature, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1977-09-14 to 1981-04-20 (NODC Accession 8100585)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, temperature, salinity, and other data were collected using moored current meter casts and other instruments in the Gulf of Mexico from September...

Current direction, wind wave spectra, phytoplankton, and other data from moored current meter casts in the Gulf of Mexico during the Brine Disposal project, 1977-09-24 to 1981-05-31 (NODC Accession 8100612)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, wind wave spectra, phytoplankton, temperature, salinity, and other data were collected using moored current meter casts in the Gulf of Mexico from...

Acute Embolic Myocardial Infarction in a Patient with Paroxysmal Atrial Fibrillation Receiving Direct-current Cardioversion

Directory of Open Access Journals (Sweden)

Tung-Chao Lin

2009-03-01

Full Text Available Coronary embolism with acute myocardial infarction (MI following direct-current (DC cardioversion of atrial fibrillation (AF has rarely been reported. We present the case of a 34-year-old female with severe aortic regurgitation and highly symptomatic paroxysmal AF. Acute embolic MI occurred 4 days after DC cardioversion of AF, although there was no left atrial thrombus detected before this procedure. Insufficient anticoagulation therapy during the post-cardioversion period was the cause, leading to embolic MI.

Navy Telemedicine: Current Research and Future Directions

National Research Council Canada - National Science Library

Reed, Cheryl

2002-01-01

.... An assessment of Navy telemedicine as a complex healthcare support system is needed to demonstrate how current practices, training, equipment, and expenditures measure up to the emerging needs of the Fleet...

Superconformal current multiplet

International Nuclear Information System (INIS)

Smailagic, A.

1982-12-01

We consider a derivation of a superconformal current multiplet based directly on superconformal algebra. This gives usual multiplet of currents without anomalies, directly in terms of ''improved'' quantities and without reference to a particular Lagrangian model. (author)

Calibration of an electron volt neutron spectrometer

International Nuclear Information System (INIS)

Mayers, J.; Adams, M.A.

2011-01-01

The procedure for calibrating the VESUVIO eV neutron spectrometer at the ISIS neutron source is described. VESUVIO is used primarily to measure the momentum distribution n(p) of atoms, by inelastic scattering of very high energy (5-150 eV) neutrons. The results of the calibrations show that measurements of n(p) in atoms with masses lower than 16 amu can be measured with a resolution width ∼25% of the intrinsic peak widths in the current instrument configuration. Some suggestions as to how the instrument resolution could be significantly improved are made.

The Effects of Transcranial Direct Current Stimulation (tDCS on Multitasking Throughput Capacity

Directory of Open Access Journals (Sweden)

Justin Nelson

2016-11-01

Full Text Available Background: Multitasking has become an integral attribute associated with military operations within the past several decades. As the amount of information that needs to be processed during these high level multitasking environments exceeds the human operators’ capabilities, the information throughput capacity reaches an asymptotic limit. At this point, the human operator can no longer effectively process and respond to the incoming information resulting in a plateau or decline in performance. The objective of the study was to evaluate the efficacy of a non-invasive brain stimulation technique known as transcranial direct current stimulation (tDCS applied to a scalp location over the left dorsolateral prefrontal cortex (lDLPFC to improve information processing capabilities during a multitasking environment. Methods: The study consisted of 20 participants from Wright-Patterson Air Force Base (16 male and 4 female with an average age of 31.1 (SD = 4.5. Participants were randomly assigned into two groups, each consisting of eight males and two females. Group one received 2mA of anodal tDCS and group two received sham tDCS over the lDLPFC on their testing day. Results: The findings indicate that anodal tDCS significantly improves the participants’ information processing capability resulting in improved performance compared to sham tDCS. For example, the multitasking throughput capacity for the sham tDCS group plateaued near 1.0 bits/s at the higher baud input (2.0 bits/s whereas the anodal tDCS group plateaued near 1.3 bits/s. Conclusion: The findings provided new evidence that tDCS has the ability to augment and enhance multitasking capability in a human operator. Future research should be conducted to determine the longevity of the enhancement of transcranial direct current stimulation on multitasking performance, which has yet to be accomplished.

The Effects of Transcranial Direct Current Stimulation (tDCS) on Multitasking Throughput Capacity.

Science.gov (United States)

Nelson, Justin; McKinley, Richard A; Phillips, Chandler; McIntire, Lindsey; Goodyear, Chuck; Kreiner, Aerial; Monforton, Lanie

2016-01-01

Background: Multitasking has become an integral attribute associated with military operations within the past several decades. As the amount of information that needs to be processed during these high level multitasking environments exceeds the human operators' capabilities, the information throughput capacity reaches an asymptotic limit. At this point, the human operator can no longer effectively process and respond to the incoming information resulting in a plateau or decline in performance. The objective of the study was to evaluate the efficacy of a non-invasive brain stimulation technique known as transcranial direct current stimulation (tDCS) applied to a scalp location over the left dorsolateral prefrontal cortex (lDLPFC) to improve information processing capabilities during a multitasking environment. Methods: The study consisted of 20 participants from Wright-Patterson Air Force Base (16 male and 4 female) with an average age of 31.1 (SD = 4.5). Participants were randomly assigned into two groups, each consisting of eight males and two females. Group one received 2 mA of anodal tDCS and group two received sham tDCS over the lDLPFC on their testing day. Results: The findings indicate that anodal tDCS significantly improves the participants' information processing capability resulting in improved performance compared to sham tDCS. For example, the multitasking throughput capacity for the sham tDCS group plateaued near 1.0 bits/s at the higher baud input (2.0 bits/s) whereas the anodal tDCS group plateaued near 1.3 bits/s. Conclusion: The findings provided new evidence that tDCS has the ability to augment and enhance multitasking capability in a human operator. Future research should be conducted to determine the longevity of the enhancement of transcranial direct current stimulation on multitasking performance, which has yet to be accomplished.

Comments on the current status and possible future directions of research on heavy-ion interactions near the Coulomb barrier

International Nuclear Information System (INIS)

Satchler, G.R.

1990-01-01

This paper contains comments on the current status and possible future directions of research on heavy-ion interactions near the Coulomb barrier. Fusion reactions, elastic and inelastic scattering and transfer reactions are discussed

18/20 T high magnetic field scanning tunneling microscope with fully low voltage operability, high current resolution, and large scale searching ability.

Science.gov (United States)

Li, Quanfeng; Wang, Qi; Hou, Yubin; Lu, Qingyou

2012-04-01

We present a home-built 18/20 T high magnetic field scanning tunneling microscope (STM) featuring fully low voltage (lower than ±15 V) operability in low temperatures, large scale searching ability, and 20 fA high current resolution (measured by using a 100 GOhm dummy resistor to replace the tip-sample junction) with a bandwidth of 3.03 kHz. To accomplish low voltage operation which is important in achieving high precision, low noise, and low interference with the strong magnetic field, the coarse approach is implemented with an inertial slider driven by the lateral bending of a piezoelectric scanner tube (PST) whose inner electrode is axially split into two for enhanced bending per volt. The PST can also drive the same sliding piece to inertial slide in the other bending direction (along the sample surface) of the PST, which realizes the large area searching ability. The STM head is housed in a three segment tubular chamber, which is detachable near the STM head for the convenience of sample and tip changes. Atomic resolution images of a graphite sample taken under 17.6 T and 18.0001 T are presented to show its performance. © 2012 American Institute of Physics

Synthesis of thick diamond films by direct current hot-cathode plasma chemical vapour deposition

CERN Document Server

Jin Zeng Sun; Bai Yi Zhen; Lu Xian Yi

2002-01-01

The method of direct current hot-cathode plasma chemical vapour deposition has been established. A long-time stable glow discharge at large discharge current and high gas pressure has been achieved by using a hot cathode in the temperature range from 1100 degree C to 1500 degree C and non-symmetrical configuration of the poles, in which the diameter of the cathode is larger than that of anode. High-quality thick diamond films, with a diameter of 40-50 mm and thickness of 0.5-4.2 mm, have been synthesized by this method. Transparent thick diamond films were grown over a range of growth rates between 5-10 mu m/h. Most of the thick diamond films have thermal conductivities of 10-12 W/K centre dot cm. The thick diamond films with high thermal conductivity can be used as a heat sink of semiconducting laser diode array and as a heat spreading and isolation substrate of multichip modules. The performance can be obviously improved

Current direction and wind wave spectra data from moored current meter casts in the Gulf of Mexico as part of the Brine Disposal project, 1977-12-22 to 1978-07-01 (NODC Accession 7900123)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, temperature, and wind wave spectra data were collected using moored current meter casts in the Gulf of Mexico from December 22, 1977 to October...

Current direction, chemical, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1980-12-13 to 1982-03-01 (NODC Accession 8200097)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, chemical, and other data were collected using moored current meter casts and other instruments in the Gulf of Mexico from December 13, 1980 to...

Anodal transcranial direct current stimulation of parietal cortex enhances action naming in Corticobasal Syndrome

Directory of Open Access Journals (Sweden)

Rosa eManenti

2015-04-01

Full Text Available Background: Corticobasal Syndrome (CBS is a neurodegenerative disorder that overlaps both clinically and neuropathologically with Frontotemporal dementia and is characterized by apraxia, alien limb phenomena, cortical sensory loss, cognitive impairment, behavioural changes and aphasia. It has been recently demonstrated that transcranial direct current stimulation (tDCS improves naming in healthy subjects and in subjects with language deficits.Objective: The aim of the present study was to explore the extent to which anodal transcranial direct current stimulation (anodal tDCS over the parietal cortex (PARC could facilitate naming performance in CBS subjects. Methods: Anodal tDCS was applied to the left and right PARC during object and action naming in seventeen patients with a diagnosis of possible CBS. Participants underwent two sessions of anodal tDCS (left and right and one session of placebo tDCS. Vocal responses were recorded and analyzed for accuracy and vocal Reaction Times (vRTs. Results: A shortening of naming latency for actions was observed only after active anodal stimulation over the left PARC, as compared to placebo and right stimulations. No effects have been reported for accuracy.Conclusions: Our preliminary finding demonstrated that tDCS decreased vocal reaction time during action naming in a sample of patients with CBS. A possible explanation of our results is that anodal tDCS over the left PARC effects the brain network implicated in action observation and representation. Further studies, based on larger patient samples, should be conducted to investigate the usefulness of tDCS as an additional treatment of linguistic deficits in CBS patients.

Unilateral prefrontal direct current stimulation effects are modulated by working memory load and gender.

Science.gov (United States)

Meiron, Oded; Lavidor, Michal

2013-05-01

Recent studies revealed that anodal transcranial direct current stimulation (tDCS) to the left dorsolateral prefrontal cortex (DLPFC) may improve verbal working memory (WM) performance in humans. In the present study, we evaluated executive attention, which is the core of WM capacity, considered to be significantly involved in tasks that require active maintenance of memory representations in interference-rich conditions, and is highly dependent on DLPFC function. We investigated verbal WM accuracy using a WM task that is highly sensitive to executive attention function. We were interested in how verbal WM accuracy may be affected by WM load, unilateral DLPFC stimulation, and gender, as previous studies showed gender-dependent brain activation during verbal WM tasks. We utilized a modified verbal n-Back task hypothesized to increase demands on executive attention. We examined "online" WM performance while participants received transcranial direct current stimulation (tDCS), and implicit learning performance in a post-stimulation WM task. Significant lateralized "online" stimulation effects were found only in the highest WM load condition revealing that males benefit from left DLPFC stimulation, while females benefit from right DLPFC stimulation. High WM load performance in the left DLPFC stimulation was significantly related to post-stimulation recall performance. Our findings support the idea that lateralized stimulation effects in high verbal WM load may be gender-dependent. Further, our post-stimulation results support the idea that increased left hemisphere activity may be important for encoding verbal information into episodic memory as well as for facilitating retrieval of context-specific targets from semantic memory. Copyright © 2013 Elsevier Inc. All rights reserved.

Current direction and wind wave spectra data from moored current meter casts in the Gulf of Mexico as part of the Brine Disposal project, 1977-02-02 to 1979-01-31 (NODC Accession 7900144)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, salinity, and wind wave spectra data were collected using moored current meter casts in the Gulf of Mexico from February 2, 1978 to January 31,...

Current direction and wind wave spectra data from moored current meter casts in the Gulf of Mexico as part of the Brine Disposal project, 1978-06-28 to 1978-12-31 (NODC Accession 7900128)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, temperature, and wind wave spectra data were collected using moored current meter casts in the Gulf of Mexico from June 28, 1978 to December 31,...

Does transcranial direct current stimulation affect the learning of a fine sequential hand motor skill with motor imagery?

NARCIS (Netherlands)

Sobierajewicz, Jagna; Jaskowski, Wojciech; van der Lubbe, Robert Henricus Johannes

2017-01-01

Learning a fine sequential hand motor skill, comparable to playing the piano or learning to type, improves not only due to physical practice, but also due to motor imagery. Previous studies revealed that transcranial direct current stimulation (tDCS) and motor imagery independently affect motor

Cerebellar transcranial direct current stimulation improves adaptive postural control.

Science.gov (United States)

Poortvliet, Peter; Hsieh, Billie; Cresswell, Andrew; Au, Jacky; Meinzer, Marcus

2018-01-01

Rehabilitation interventions contribute to recovery of impaired postural control, but it remains a priority to optimize their effectiveness. A promising strategy may involve transcranial direct current stimulation (tDCS) of brain areas involved in fine-tuning of motor adaptation. This study explored the effects of cerebellar tDCS (ctDCS) on postural recovery from disturbance by Achilles tendon vibration. Twenty-eight healthy volunteers participated in this sham-ctDCS controlled study. Standing blindfolded on a force platform, four trials were completed: 60 s quiet standing followed by 20 min active (anodal-tDCS, 1 mA, 20 min, N = 14) or sham-ctDCS (40 s, N = 14) tDCS; three quiet standing trials with 15 s of Achilles tendon vibration and 25 s of postural recovery. Postural steadiness was quantified as displacement, standard deviation and path derived from the center of pressure (COP). Baseline demographics and quiet standing postural steadiness, and backwards displacement during vibration were comparable between groups. However, active-tDCS significantly improved postural steadiness during vibration and reduced forward displacement and variability in COP derivatives during recovery. We demonstrate that ctDCS results in short-term improvement of postural adaptation in healthy individuals. Future studies need to investigate if multisession ctDCS combined with training or rehabilitation interventions can induce prolonged improvement of postural balance. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Cerebellar transcranial direct current stimulation modulates verbal working memory.

Science.gov (United States)

Boehringer, Andreas; Macher, Katja; Dukart, Juergen; Villringer, Arno; Pleger, Burkhard

2013-07-01

Neuroimaging studies show cerebellar activations in a wide range of cognitive tasks and patients with cerebellar lesions often present cognitive deficits suggesting a cerebellar role in higher-order cognition. We used cathodal transcranial direct current stimulation (tDCS), known to inhibit neuronal excitability, over the cerebellum to investigate if cathodal tDCS impairs verbal working memory, an important higher-order cognitive faculty. We tested verbal working memory as measured by forward and backward digit spans in 40 healthy young participants before and after applying cathodal tDCS (2 mA, stimulation duration 25 min) to the right cerebellum using a randomized, sham-controlled, double-blind, cross-over design. In addition, we tested the effect of cerebellar tDCS on word reading, finger tapping and a visually cued sensorimotor task. In line with lower digit spans in patients with cerebellar lesions, cerebellar tDCS reduced forward digit spans and blocked the practice dependent increase in backward digit spans. No effects of tDCS on word reading, finger tapping or the visually cued sensorimotor task were found. Our results support the view that the cerebellum contributes to verbal working memory as measured by forward and backward digit spans. Moreover, the induction of reversible "virtual cerebellar lesions" in healthy individuals by means of tDCS may improve our understanding of the mechanistic basis of verbal working memory deficits in patients with cerebellar lesions. Copyright © 2013 Elsevier Inc. All rights reserved.

Noninvasive transcranial direct current stimulation (tDCS) for the treatment of orofacial pain.

Science.gov (United States)

Fricova, Jitka; Englerova, Katerina; Rokyta, Richard

2016-10-01

tDCS is a promising method for the treatment of chronic pain. Electrode placement locations must be chosen in accordance with the density and the time course of the current in order to prevent pathological changes in the underlying tissue. In order to reduce current spatial variability, more electrodes of the same polarity are placed in a circle around the second electrode of the opposite polarity. The applied current produced the greatest changes directly beneath the electrodes: the cathode reduces the excitability of cortical neurons, while the anode has the opposite effect. Based on inclusion criteria, 10 patients with chronic orofacial pain, secondary trigeminal neuralgia after oral surgery, were enrolled and underwent both anode and cathode stimulation. Before the first session we measured pain intensity on a numeric pain rating scale and tactile and thermal stimulation were used to assess somatosensory status. tDCS was applied for five consecutive days. At the end of tDCS application, somatosensory status was assessed again. From our results we can conclude that the application of tDCS improves the perception of some types of pain. When we increase our sample size, we would expect confirmation not only on our positive results, but also some additional findings for explaining the pathophysiology of orofacial pain. These pathophysiological findings and explanations are very important for the application of tDCS in the treatment of orofacial pain and also for other types of neuropathic pain.

Microwave testing of high-Tc based direct current to a single flux quantum converter

DEFF Research Database (Denmark)

Kaplunenko, V. K.; Fischer, Gerd Michael; Ivanov, Z. G.

1994-01-01

Design, simulation, and experimental investigations of a direct current to a single flux quantum converter loaded with a Josephson transmission line and driven by an external 70 GHz microwave oscillator are reported. The test circuit includes nine YBaCuO Josephson junctions aligned on the grain...... boundary of a 0°–32° asymmetric Y-ZrO2 bicrystal substrate. The performance of such converters is important for the development of the fast Josephson samplers required for testing of high-Tc rapid single flux quantum circuits in high-speed digital superconducting electronics. Journal of Applied Physics...

High-Definition transcranial direct current stimulation in early onset epileptic encephalopathy: a case study.

Science.gov (United States)

Meiron, Oded; Gale, Rena; Namestnic, Julia; Bennet-Back, Odeya; David, Jonathan; Gebodh, Nigel; Adair, Devin; Esmaeilpour, Zeinab; Bikson, Marom

2018-01-01

Early onset epileptic encephalopathy is characterized by high daily seizure-frequency, multifocal epileptic discharges, severe psychomotor retardation, and death at infancy. Currently, there are no effective treatments to alleviate seizure frequency and high-voltage epileptic discharges in these catastrophic epilepsy cases. The current study examined the safety and feasibility of High-Definition transcranial direct current stimulation (HD-tDCS) in reducing epileptiform activity in a 30-month-old child suffering from early onset epileptic encephalopathy. HD-tDCS was administered over 10 intervention days spanning two weeks including pre- and post-intervention video-EEG monitoring. There were no serious adverse events or side effects related to the HD-tDCS intervention. Frequency of clinical seizures was not significantly reduced. However, interictal sharp wave amplitudes were significantly lower during the post-intervention period versus baseline. Vital signs and blood biochemistry remained stable throughout the entire study. These exploratory findings support the safety and feasibility of 4 × 1 HD-tDCS in early onset epileptic encephalopathy and provide the first evidence of HD-tDCS effects on paroxysmal EEG features in electroclinical cases under the age of 36 months. Extending HD-tDCS treatment may enhance electrographic findings and clinical effects.

Current direction, chemical, phytoplankton, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1977-11-21 to 1981-09-09 (NODC Accession 8200008)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, chemical, phytoplankton, zooplankton, and other data were collected using moored current meter casts and other instruments in the Gulf of Mexico...

Out of hospital point of care ultrasound: current use models and future directions.

Science.gov (United States)

Nelson, B P; Sanghvi, A

2016-04-01

Ultrasound has evolved from a modality that was once exclusively reserved to certain specialities of its current state, in which its portability and durability lend to its broadly increasing applications. This review describes portable ultrasound in the hospital setting and its comparison to gold standard imaging modalities. Also, this review summarizes current literature describing portable ultrasound use in prehospital, austere and remote environments, highlighting successes and barriers to use in these environments. Prehospital ultrasound has the ability to increase diagnostic ability and allow for therapeutic intervention in the field. In austere environments, ultrasound may be the only available imaging modality and thus can guide diagnosis, therapeutics and determine which patients may need emergent transfer to a healthcare facility. The most cutting edge applications of portable ultrasound employ telemedicine to obtain and transmit ultrasound images. This technology and ability to transmit images via satellite and cellular transmission can allow for even novice users to obtain interpretable images in austere environments. Portable ultrasound uses have steadily grown and will continue to do so with the introduction of more portable and durable technologies. As applications continue to grow, certain technologic considerations and future directions are explored.

Current Status and Future Directions of Botulinum Neurotoxins for Targeting Pain Processing

Directory of Open Access Journals (Sweden)

Sabine Pellett

2015-11-01

Full Text Available Current evidence suggests that botulinum neurotoxins (BoNTs A1 and B1, given locally into peripheral tissues such as skin, muscles, and joints, alter nociceptive processing otherwise initiated by inflammation or nerve injury in animal models and humans. Recent data indicate that such locally delivered BoNTs exert not only local action on sensory afferent terminals but undergo transport to central afferent cell bodies (dorsal root ganglia and spinal dorsal horn terminals, where they cleave SNAREs and block transmitter release. Increasing evidence supports the possibility of a trans-synaptic movement to alter postsynaptic function in neuronal and possibly non-neuronal (glial cells. The vast majority of these studies have been conducted on BoNT/A1 and BoNT/B1, the only two pharmaceutically developed variants. However, now over 40 different subtypes of botulinum neurotoxins (BoNTs have been identified. By combining our existing and rapidly growing understanding of BoNT/A1 and /B1 in altering nociceptive processing with explorations of the specific characteristics of the various toxins from this family, we may be able to discover or design novel, effective, and long-lasting pain therapeutics. This review will focus on our current understanding of the molecular mechanisms whereby BoNTs alter pain processing, and future directions in the development of these agents as pain therapeutics.

Current direction, chemical, zooplankton, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1978-09-22 to 1979-01-22 (NODC Accession 7900212)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, chemical, zooplankton, and other data were collected using moored current meter casts and other instruments in the Gulf of Mexico from September...

Loyalty Programmes : Current Knowledge and Research Directions

NARCIS (Netherlands)

Dorotic, Matilda; Bijmolt, Tammo H. A.; Verhoef, Peter C.

Loyalty programmes (LPs) have increased in number and popularity, but their effects on customer behaviour remain equivocal, due to a lack of understanding of the drivers of LP effectiveness and insufficient generalizable conclusions across prior studies. This paper synthesizes current knowledge

Direct numerical simulations of particle-laden density currents with adaptive, discontinuous finite elements

Directory of Open Access Journals (Sweden)

S. D. Parkinson

2014-09-01

Full Text Available High-resolution direct numerical simulations (DNSs are an important tool for the detailed analysis of turbidity current dynamics. Models that resolve the vertical structure and turbulence of the flow are typically based upon the Navier–Stokes equations. Two-dimensional simulations are known to produce unrealistic cohesive vortices that are not representative of the real three-dimensional physics. The effect of this phenomena is particularly apparent in the later stages of flow propagation. The ideal solution to this problem is to run the simulation in three dimensions but this is computationally expensive. This paper presents a novel finite-element (FE DNS turbidity current model that has been built within Fluidity, an open source, general purpose, computational fluid dynamics code. The model is validated through re-creation of a lock release density current at a Grashof number of 5 × 106 in two and three dimensions. Validation of the model considers the flow energy budget, sedimentation rate, head speed, wall normal velocity profiles and the final deposit. Conservation of energy in particular is found to be a good metric for measuring model performance in capturing the range of dynamics on a range of meshes. FE models scale well over many thousands of processors and do not impose restrictions on domain shape, but they are computationally expensive. The use of adaptive mesh optimisation is shown to reduce the required element count by approximately two orders of magnitude in comparison with fixed, uniform mesh simulations. This leads to a substantial reduction in computational cost. The computational savings and flexibility afforded by adaptivity along with the flexibility of FE methods make this model well suited to simulating turbidity currents in complex domains.

The effect of using sun tracking systems on the voltage-current characteristics and power generation of flat plate photovoltaics

International Nuclear Information System (INIS)

Abdallah, Salah

2004-01-01

An experimental study was performed to investigate the effect of using different types of sun tracking systems on the voltage-current characteristics and electrical power generation at the output of flat plate photovoltaics (FPPV). Four electromechanical sun tracking systems, two axes, one axis vertical, one axis east-west and one axis north-south, were designed and constructed for the purpose of investigating the effect of tracking on the electrical values, current, voltage and power, according to the different loads (variable resistance). The above mentioned variables were measured at the output of the FPPV and compared with those on a fixed surface. The results indicated that the volt-ampere characteristics on the tracking surfaces were significantly greater than that on a fixed surface. There were increases of electrical power gain up to 43.87%, 37.53%, 34.43% and 15.69% for the two axes, east-west, vertical and north-south tracking, respectively, as compared with the fixed surface inclined 32 deg. to the south in Amman, Jordan

Determination of metal impurities in MOX powder by direct current arc atomic emission spectroscopy. Application of standard addition method for direct analysis of powder sample

International Nuclear Information System (INIS)

Furuse, Takahiro; Taguchi, Shigeo; Kuno, Takehiko; Surugaya, Naoki

2016-12-01

Metal impurities in MOX powder obtained from uranium and plutonium recovered from reprocessing process of spent nuclear fuel have to be determined for its characterization. Direct current arc atomic emission spectroscopy (DCA-AES) is one of the useful methods for direct analysis of powder sample without dissolving the analyte into aqueous solution. However, the selection of standard material, which can overcome concerns such as matrix matching, is quite important to create adequate calibration curves for DCA-AES. In this study, we apply standard addition method using the certified U_3O_8 containing known amounts of metal impurities to avoid the matrix problems. The proposed method provides good results for determination of Fe, Cr and Ni contained in MOX samples at a significant quantity level. (author)

High improvement in trap level density and direct current breakdown strength of block polypropylene by doping with a β-nucleating agent

Science.gov (United States)

Zhang, Chong; Zha, Jun-Wei; Yan, Hong-Da; Li, Wei-Kang; Dang, Zhi-Min

2018-02-01

Polypropylene is one kind of eco-friendly insulating material, which has attracted more attention for use in high voltage direct current (HVDC) insulation due to the long-distance transmission, low loss, and recyclability. In this work, the morphology and thermal and electrical properties of the block polypropylene with various β-nucleating agent (β-NA) contents were investigated. The relative fraction of the β-crystal can reach 64.7% after adding 0.05 wt. % β-NA. The β-NA also greatly reduced the melting point and improved the crystallization temperature. The electrical property results showed that the alternating and direct current breakdown strength and conduction current were obviously improved. In addition, space charge accumulation was significantly suppressed by introducing the β-NA. This work provides an attractive strategy of design and fabrication of polypropylene for HVDC application.

Effect of electrothermal annealing on the transformation behavior of TiNi shape memory alloy and two-way shape memory spring actuated by direct electrical current

International Nuclear Information System (INIS)

Wang, Z.G.; Zu, X.T.; Feng, X.D.; Zhu, S.; Deng, J.; Wang, L.M.

2004-01-01

In this work, the effect of electrothermal annealing on the transformation characterization of TiNi shape memory alloy and the electrothermal actuating characteristics of a two-way shape memory effect (TWSME) extension spring were investigated with direct electrical current. The results showed that with increasing direct electrical current density, the B2→R-phase transformation shifts to a lower temperature and R-phase→B19' shifts to a higher temperature in the cooling process. When annealing electrical current density reached 12.2 A/mm 2 , the R-phase disappeared and austenite transformed into martensite directly. The electrothermal annealing was an effective method of heat treatment in a selected part of shape memory alloy device. The electrothermal actuating characteristics of a TWSME spring showed that the time response and the maximum elongation greatly depended on the magnitude of the electrical current

Current and Potential Chinese Foreign Direct Investment in the Slovak Republic

Directory of Open Access Journals (Sweden)

Zhang Liqun

2017-06-01

Full Text Available This article presents an overview of current and potential investment from China into the Slovak Republic within the broader CEEC region cooperation based on the 16+1 platform. Based on a business study on the automotive industry in the CEEC region, and particularly Slovakia as one of the industrial sectors for possible Chinese investment with immense potential, the article aims to identify the main advantages and disadvantages of the region as a foreign direct investment destination. The article also analyses the impact of FDI inflows on the Slovak economy. We come to the conclusion that the recent FDI inflow from China to Slovakia has been statistically insignificant, which may, however, change in case the envisaged Chinese investment into the steel industry in Slovakia will be realised. With respect thereto, the article also points at the need to set out a new revised framework for the international legal protection of Chinese investment in the EU. It has been established that further research is required to assess the impact of Chinese FDI on the Slovak economy.

Direct-current vector control of three-phase grid-connected rectifier-inverter

Energy Technology Data Exchange (ETDEWEB)

Li, Shuhui; Haskew, Timothy A.; Hong, Yang-Ki; Xu, Ling [Department of Electrical and Computer Engineering, University of Alabama, Tuscaloosa, AL 35475 (United States)

2011-02-15

The three-phase grid-connected converter is widely used in renewable and electric power system applications. Traditionally, control of the three-phase grid-connected converter is based on the standard decoupled d-q vector control mechanism. Nevertheless, the study of this paper shows that there is a limitation in the conventional standard vector control method. Some of the limitations have also been found recently by other researchers. To overcome the shortage of the conventional vector control technique, this paper proposes a new direct-current d-q vector control mechanism in a nested-loop control structure, based on which an optimal control strategy is developed in a nonlinear programming formulation. The behaviors of both the conventional and proposed control methods are compared and evaluated in simulation and laboratory hardware experiment environments, both of which demonstrates that the proposed approach is effective for grid-connected power converter control in a wide system conditions while the conventional standard vector control approach may behave improperly especially when the converter operates beyond its PWM saturation limit. (author)

THE ASSESSMENT OF ENTREPRENEURIAL PERSONALITY: THE CURRENT SITUATION AND FUTURE DIRECTIONS

Directory of Open Access Journals (Sweden)

Javier Suárez-Álvarez

2016-01-01

Full Text Available Entrepreneurship is fundamental in modern society because it represents an important source of innovation, employment, productivity, and growth. While the first theoretical models arose from economic and sociological approaches, psychology provides models that integrate different aspects such as cognitions, attitudes and personality, which allow a more detailed study. The purpose of this paper is to show the main contributions of psychology to the assessment of the enterprising personality. For this purpose, the main models and instruments developed to date were reviewed. The results confirm that the enterprising personality has a multidimensional structure and eight personality traits can be highlighted: achievement motivation, risk-taking, autonomy, self-efficacy, stress tolerance, innovativeness, internal locus of control, and optimism. From a methodological point of view, Item Response Theory and Computerised Adaptive Tests represent the most advanced and modern methods for assessing enterprising personality. There are currently several measurement instruments available. Future areas of research should be directed at the construction of multidimensional models as well as providing alternatives that facilitate a reduction in social desirability and other biases inherent in self-reports.

Mouse housing system using pressurized cages intraventilated by direct-current microfans.

Science.gov (United States)

Martinewski, Alexandre; Correia, Caio S C; de Souza, Nívea L; Merusse, José L B

2012-03-01

We performed the initial assessment of an alternative pressurized intraventilated (PIV) caging system for laboratory mice that uses direct-current microfans to achieve cage pressurization and ventilation. Twenty-nine pairs of female SPF BALB/c mice were used, with 19 experimental pairs kept in PIV cages and 10 control pairs kept in regular filter-top (FT) cages. Both groups were housed in a standard housing room with a conventional atmospheric control system. For both systems, intracage temperatures were in equilibrium with ambient room temperature. PIV cages showed a significant difference in pressure between days 1 and 8. Air speed (and consequently airflow rate) and the number of air changes hourly in the PIV cages showed decreasing trends. In both systems, ammonia concentrations increased with time, with significant differences between groups starting on day 1. Overall, the data revealed that intracage pressurization and ventilation by using microfans is a simple, reliable system, with low cost, maintenance requirements, and incidence of failures. Further experiments are needed to determine the potential influence of this system on the reproductive performance and pulmonary integrity in mice.

Waste of paper or useful tool? The potential of the temporary protection directive in the current "Refugee crisis"

NARCIS (Netherlands)

Gluns, Danielle; Wessels, Janna

2017-01-01

The Council Directive 2001/55/EC on temporary protection in the event of a "mass influx" of displaced persons provides for a mechanism that shall lead to collaborative efforts of the European Union Member States in dealing with persons seeking protection in Europe. In spite of the current "refugee

Transcranial direct current stimulation in refractory continuous spikes and waves during slow sleep: a controlled study

DEFF Research Database (Denmark)

Varga, Edina T; Terney, Daniella; Atkins, Mary D

2011-01-01

Cathodal transcranial direct current stimulation (tDCS) decreases cortical excitability. The purpose of the study was to investigate whether cathodal tDCS could interrupt the continuous epileptiform activity. Five patients with focal, refractory continuous spikes and waves during slow sleep were...... recruited. Cathodal tDCS and sham stimulation were applied to the epileptic focus, before sleep (1 mA; 20 min). Cathodal tDCS did not reduce the spike-index in any of the patients....

Current direction, benthic organisms, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1978-09-01 to 1982-05-19 (NODC Accession 8200154)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, benthic organisms, and other data were collected using moored current meter casts in the Gulf of Mexico from July 15, 1980 to March 20, 1981. Data...

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

Directory of Open Access Journals (Sweden)

Matthew F Tang

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

Effectiveness of transcranial direct current stimulation preceding cognitive behavioural management for chronic low back pain: sham controlled double blinded randomised controlled trial.

Science.gov (United States)

Luedtke, Kerstin; Rushton, Alison; Wright, Christine; Jürgens, Tim; Polzer, Astrid; Mueller, Gerd; May, Arne

2015-04-16

To evaluate the effectiveness of transcranial direct current stimulation alone and in combination with cognitive behavioural management in patients with non-specific chronic low back pain. Double blind parallel group randomised controlled trial with six months' follow-up conducted May 2011-March 2013. Participants, physiotherapists, assessors, and analyses were blinded to group allocation. Interdisciplinary chronic pain centre. 135 participants with non-specific chronic low back pain >12 weeks were recruited from 225 patients assessed for eligibility. Participants were randomised to receive anodal (20 minutes to motor cortex at 2 mA) or sham transcranial direct current stimulation (identical electrode position, stimulator switched off after 30 seconds) for five consecutive days immediately before cognitive behavioural management (four week multidisciplinary programme of 80 hours). Two primary outcome measures of pain intensity (0-100 visual analogue scale) and disability (Oswestry disability index) were evaluated at two primary endpoints after stimulation and after cognitive behavioural management. Analyses of covariance with baseline values (pain or disability) as covariates showed that transcranial direct current stimulation was ineffective for the reduction of pain (difference between groups on visual analogue scale 1 mm (99% confidence interval -8.69 mm to 6.3 mm; P=0.68)) and disability (difference between groups 1 point (-1.73 to 1.98; P=0.86)) and did not influence the outcome of cognitive behavioural management (difference between group 3 mm (-10.32 mm to 6.73 mm); P=0.58; difference between groups on Oswestry disability index 0 point (-2.45 to 2.62); P=0.92). The stimulation was well tolerated with minimal transitory side effects. This results of this trial on the effectiveness of transcranial direct current stimulation for the reduction of pain and disability do not support its clinical use for managing non-specific chronic low back pain

Current direction, zooplankton, phytoplankton, benthic organisms, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 17 February 1981 - 22 June 1982 (NODC Accession 8200230)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, phytoplankton, zooplankton, benthic organisms, and other data were collected using moored current meter casts and other instruments in the Gulf of...

Current direction, chemical, zooplankton, phytoplankton, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1980-01-24 to 1981-06-22 (NODC Accession 8100704)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, chemical, phytoplankton, zooplankton, and other data were collected using moored current meter casts and other instruments in the Gulf of Mexico...

Current direction, chemical, phytoplankton, zooplankton, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1977-09-15 to 1981-05-27 (NODC Accession 8100657)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, chemical, phytoplankton, zooplankton, and other data were collected using moored current meter casts and other instruments in the Gulf of Mexico...

Current direction, chemical, zooplankton, phytoplankton, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1982-02-19 to 1983-03-23 (NODC Accession 8300099)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, chemical, phytoplankton, zooplankton, and other data were collected using moored current meter casts and other instruments in the Gulf of Mexico...

Load Torque Compensator for Model Predictive Direct Current Control in High Power PMSM Drive Systems

DEFF Research Database (Denmark)

Preindl, Matthias; Schaltz, Erik

2011-01-01

The widely used cascade speed and torque controllers have a limited control performance in most high power applications due to the low switching frequency of power electronic converters and the convenience to avoid speed overshoots and oscillations for lifetime considerations. Model Predictive...... Direct Current Control (MPDCC) leads to an increase of torque control performance taking into account the discrete nature of inverters but temporary offsets and poor responses to load torque variations are still issues in speed control. A load torque estimator is proposed in this paper in order...

Effects of alternating and direct current in electrocoagulation process on the removal of cadmium from water

Energy Technology Data Exchange (ETDEWEB)

Vasudevan, Subramanyan, E-mail: vasudevan65@gmail.com [CSIR-Central Electrochemical Research Institute, Karaikudi 630 006 (India); Lakshmi, Jothinathan; Sozhan, Ganapathy [CSIR-Central Electrochemical Research Institute, Karaikudi 630 006 (India)

2011-08-15

Highlights: {yields} Very high removal efficiency of cadmium was achieved by electrocoagulation. {yields} Alternating current (AC) avoids oxide layer and corrosion on anode surface. {yields} Good current transfer between anode and cathode results more removal efficiency. {yields} Compact treatment facility and complete automation. {yields} Aluminum alloy anode prevents residual aluminum in treated water. - Abstract: In practice, direct current (DC) is used in an electrocoagulation processes. In this case, an impermeable oxide layer may form on the cathode as well as corrosion formation on the anode due to oxidation. This prevents the effective current transfer between the anode and cathode, so the efficiency of electrocoagulation processes declines. These disadvantages of DC have been diminished by adopting alternating current (AC) in electrocoagulation processes. The main objective of this study is to investigate the effects of AC and DC on the removal of cadmium from water using aluminum alloy as anode and cathode. The results showed that the removal efficiency of 97.5 and 96.2% with the energy consumption of 0.454 and 1.002 kWh kl{sup -1} was achieved at a current density of 0.2 A/dm{sup 2} and pH of 7.0 using aluminum alloy as electrodes using AC and DC, respectively. For both AC and DC, the adsorption of cadmium was preferably fitting Langmuir adsorption isotherm, the adsorption process follows second order kinetics and the temperature studies showed that adsorption was exothermic and spontaneous in nature.

Effects of alternating and direct current in electrocoagulation process on the removal of cadmium from water

International Nuclear Information System (INIS)

Vasudevan, Subramanyan; Lakshmi, Jothinathan; Sozhan, Ganapathy

2011-01-01

Highlights: → Very high removal efficiency of cadmium was achieved by electrocoagulation. → Alternating current (AC) avoids oxide layer and corrosion on anode surface. → Good current transfer between anode and cathode results more removal efficiency. → Compact treatment facility and complete automation. → Aluminum alloy anode prevents residual aluminum in treated water. - Abstract: In practice, direct current (DC) is used in an electrocoagulation processes. In this case, an impermeable oxide layer may form on the cathode as well as corrosion formation on the anode due to oxidation. This prevents the effective current transfer between the anode and cathode, so the efficiency of electrocoagulation processes declines. These disadvantages of DC have been diminished by adopting alternating current (AC) in electrocoagulation processes. The main objective of this study is to investigate the effects of AC and DC on the removal of cadmium from water using aluminum alloy as anode and cathode. The results showed that the removal efficiency of 97.5 and 96.2% with the energy consumption of 0.454 and 1.002 kWh kl -1 was achieved at a current density of 0.2 A/dm 2 and pH of 7.0 using aluminum alloy as electrodes using AC and DC, respectively. For both AC and DC, the adsorption of cadmium was preferably fitting Langmuir adsorption isotherm, the adsorption process follows second order kinetics and the temperature studies showed that adsorption was exothermic and spontaneous in nature.

Current direction, chemical, and marine toxic substances data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1978-09-09 to 1979-11-19 (NODC Accession 8000043)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, marine toxic substances, and chemical data were collected using moored current meter casts and other instruments in the Gulf of Mexico from...

Current direction, chemical, benthic organisms, and other data from moored current meter casts and other instruments in the Gulf of Mexico during the Brine Disposal project, 1981-01-21 to 1982-07-27 (NODC Accession 8200207)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, chemical, benthic organisms, and other data were collected using moored current meter casts and other instruments in the Gulf of Mexico from...

Statistical characteristic in time-domain of direct current corona-generated audible noise from conductor in corona cage

Energy Technology Data Exchange (ETDEWEB)

Li, Xuebao, E-mail: lxb08357x@ncepu.edu.cn; Cui, Xiang, E-mail: x.cui@ncepu.edu.cn; Ma, Wenzuo; Bian, Xingming; Wang, Donglai [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206 (China); Lu, Tiebing, E-mail: tiebinglu@ncepu.edu.cn [Beijing Key Laboratory of High Voltage and EMC, North China Electric Power University, Beijing 102206 (China); Hiziroglu, Huseyin [Department of Electrical and Computer Engineering, Kettering University, Flint, Michigan 48504 (United States)

2016-03-15

The corona-generated audible noise (AN) has become one of decisive factors in the design of high voltage direct current (HVDC) transmission lines. The AN from transmission lines can be attributed to sound pressure pulses which are generated by the multiple corona sources formed on the conductor, i.e., transmission lines. In this paper, a detailed time-domain characteristics of the sound pressure pulses, which are generated by the DC corona discharges formed over the surfaces of a stranded conductors, are investigated systematically in a laboratory settings using a corona cage structure. The amplitude of sound pressure pulse and its time intervals are extracted by observing a direct correlation between corona current pulses and corona-generated sound pressure pulses. Based on the statistical characteristics, a stochastic model is presented for simulating the sound pressure pulses due to DC corona discharges occurring on conductors. The proposed stochastic model is validated by comparing the calculated and measured A-weighted sound pressure level (SPL). The proposed model is then used to analyze the influence of the pulse amplitudes and pulse rate on the SPL. Furthermore, a mathematical relationship is found between the SPL and conductor diameter, electric field, and radial distance.

Inactivation of Staphylococcus aureus and Enterococcus faecalis by a direct-current, cold atmospheric-pressure air plasma microjet.

Science.gov (United States)

Tian, Ye; Sun, Peng; Wu, Haiyan; Bai, Na; Wang, Ruixue; Zhu, Weidong; Zhang, Jue; Liu, Fuxiang

2010-07-01

A direct-current, cold atmospheric-pressure air plasma microjet (PMJ) was performed to inactivate Staphylococcus aureus (S. aureus) and Enterococcus faecalis (E. faecalis) in air. The process of sterilization and morphology of bacteria was observed. We wish to know the possible inactivation mechanisms of PMJ and explore a potential application in dental and other temperature sensitive treatment. In this study, we employed a direct current, atmospheric pressure, cold air PMJ to inactivate bacterias. Scanning electron microscopy was employed to evaluate the morphology of S. aureus and showed rupture of cell walls after the plasma treatment and Optical emission spectrum (OES) were used to understand the possible inactivation mechanisms of PMJ. The inactivation rates could reach 100% in 5 min. When the distance between the exit nozzle of the PMJ device and Petri dish was extended from 1 cm to 3 cm, effective inactivation was also observed with a similar inactivation curve. The inactivation of bacteria is attributed to the abundant reactive oxygen and nitrogen species, as well as ultroviolet radiation in the plasma. Different life spans and defensibilities of these killing agents may hold the key to understanding the different inactivation curves at different treatment distances.

Statistical characteristic in time-domain of direct current corona-generated audible noise from conductor in corona cage