Landauer-Datta-Lundstrom model for terahertz transistor amplifier based on graphene

NASA Astrophysics Data System (ADS)

Davidovich, M. V.

2017-08-01

A transistor has been considered in the form of three electrodes connected by graphene ribbons or by metal quantum wires (nanowires) that operate on the principle of the current control by the changing voltage at the central electrode (gate). The analysis has been carried out according to the Landauer-Datta-Lundstrom model in equilibrium approximation for electrodes while fixing their potentials. We have obtained linear models and nonlinear terms in the determining current, and calculated the nonlinear current-voltage performances of graphene nanoribbons.

Therapeutic options for diseases due to potential viral agents of bioterrorism.

PubMed

Bronze, Michael S; Greenfield, Ronald A

2003-02-01

The etiologic agents of smallpox and viral hemorrhagic fever have emerged as potential agents of bioterrorism due to their virulence, potential for human to human dissemination and limited strategies for treatment and prevention. Cidofovir has shown significant promise in animal models, and limited case reports in humans are encouraging. Ribavirin is the treatment of choice for certain hemorrhagic fever viral infections, but has no current application to Ebola and Marburg infections. Current vaccine strategies for smallpox are effective, but carry significant risk for complications. Licensed vaccines for hemorrhagic fever viruses are limited to yellow fever, but animal studies are promising. Genomic analysis of the viral pathogen and the animal model response to infection may provide valuable information enabling the development of novel treatment and prevention strategies. Current knowledge of these strategies is reviewed.

Two-dimensional potential double layers and discrete auroras

NASA Technical Reports Server (NTRS)

Kan, J. R.; Lee, L. C.; Akasofu, S.-I.

1979-01-01

This paper is concerned with the formation of the acceleration region for electrons which produce the visible auroral arc and with the formation of the inverted V precipitation region. The former is embedded in the latter, and both are associated with field-aligned current sheets carried by plasma sheet electrons. It is shown that an electron current sheet driven from the plasma sheet into the ionosphere leads to the formation of a two-dimensional potential double layer. For a current sheet of a thickness less than the proton gyrodiameter solutions are obtained in which the field-aligned potential drop is distributed over a length much greater than the Debye length. For a current sheet of a thickness much greater than the proton gyrodiameter solutions are obtained in which the potential drop is confined to a distance on the order of the Debye length. The electric field in the two-dimensional double-layer model is the zeroth-order field inherent to the current sheet configuration, in contrast to those models in which the electric field is attributed to the first-order field due to current instabilities or turbulences. The maximum potential in the two-dimensional double-layer models is on the order of the thermal energy of plasma sheet protons, which ranges from 1 to 10 keV.

Automated Power-Distribution System

NASA Technical Reports Server (NTRS)

Thomason, Cindy; Anderson, Paul M.; Martin, James A.

1990-01-01

Automated power-distribution system monitors and controls electrical power to modules in network. Handles both 208-V, 20-kHz single-phase alternating current and 120- to 150-V direct current. Power distributed to load modules from power-distribution control units (PDCU's) via subsystem distributors. Ring busses carry power to PDCU's from power source. Needs minimal attention. Detects faults and also protects against them. Potential applications include autonomous land vehicles and automated industrial process systems.

Using Oxygen “Microbubbles” To Improve Radiation Therapy

Cancer.gov

Oxygen-carrying “microbubbles” could potentially improve the effectiveness of radiation therapy in the treatment of breast cancer, findings from a study in mice suggest. Using the bubbles along with radiation slowed tumor growth more than radiation alone, as this NCI Cancer Currents post reports.

Device, system and method for a sensing electrical circuit

NASA Technical Reports Server (NTRS)

Vranish, John M. (Inventor)

2009-01-01

The invention relates to a driven ground electrical circuit. A driven ground is a current-measuring ground termination to an electrical circuit with the current measured as a vector with amplification. The driven ground module may include an electric potential source V.sub.S driving an electric current through an impedance (load Z) to a driven ground. Voltage from the source V.sub.S excites the minus terminal of an operational amplifier inside the driven ground which, in turn, may react by generating an equal and opposite voltage to drive the net potential to approximately zero (effectively ground). A driven ground may also be a means of passing information via the current passing through one grounded circuit to another electronic circuit as input. It may ground one circuit, amplify the information carried in its current and pass this information on as input to the next circuit.

ATP-induced current in isolated outer hair cells of guinea pig cochlea.

PubMed

Nakagawa, T; Akaike, N; Kimitsuki, T; Komune, S; Arima, T

1990-05-01

1. Electrical and pharmacologic properties of ATP-induced current in outer hair cells isolated from guinea pig cochlea were investigated in the whole-cell recording mode by the use of a conventional patch-clamp technique. 2. Under current-clamp conditions, rapid application of ATP depolarized the outer hair cells resulting in an increase in conductance. The ATP-induced response did not show any desensitization during a continuous application. 3. At a holding potential of -70 mV, the ATP-induced inward current increased in a sigmoidal fashion over the concentration range between 3 microM and 1 mM. The half-maximum concentration (EC50) was 12 microM and the Hill coefficient was 0.93. 4. The ATP-induced current had a reversal potential near 6 mV, which was close to the theoretical value (1 mV) calculated from the Goldman-Hodgkin-Katz equation for permeable intra- and extracellular cations. 5. In the current-voltage (I-V) relationship for the ATP response, a slight inward-going rectification was observed at more positive potentials than the reversal potential. 6. The substitution of extracellular Na+ by equimolar choline+ shifted the reversal potential of the ATP-induced current to more negative values. The substitution of Cs+ in the internal solution by N-methyl-D-glucamine+ (NMG+) shifted it in the positive direction. The reversal potential of ATP-induced current was also shifted to positive values with increasing extracellular Ca2+ concentration. A decrease of intracellular Cl- by gluconate- did not affect the reversal potential, thereby indicating that the ATP-induced current is carried through a large cation channel.(ABSTRACT TRUNCATED AT 250 WORDS)

The Rise of Voltammetry: From Polarography to the Scanning Electrochemical Microscope

ERIC Educational Resources Information Center

Bard, Allen J.

2007-01-01

The drooping mercury electrode (DME) was previously used to carry out electrochemical experiments but invention of polarography technique changed this. Voltammetry with DME was given the term polarography and are used in measurement of current as a function of potential at small electrodes.

Charged string loops in Reissner-Nordström black hole background

NASA Astrophysics Data System (ADS)

Oteev, Tursinbay; Kološ, Martin; Stuchlík, Zdeněk

2018-03-01

We study the motion of current carrying charged string loops in the Reissner-Nordström black hole background combining the gravitational and electromagnetic field. Introducing new electromagnetic interaction between central charge and charged string loop makes the string loop equations of motion to be non-integrable even in the flat spacetime limit, but it can be governed by an effective potential even in the black hole background. We classify different types of the string loop trajectories using effective potential approach, and we compare the innermost stable string loop positions with loci of the charged particle innermost stable orbits. We examine string loop small oscillations around minima of the string loop effective potential, and we plot radial profiles of the string loop oscillation frequencies for both the radial and vertical modes. We construct charged string loop quasi-periodic oscillations model and we compare it with observed data from microquasars GRO 1655-40, XTE 1550-564, and GRS 1915+105. We also study the acceleration of current carrying string loops along the vertical axis and the string loop ejection from RN black hole neighbourhood, taking also into account the electromagnetic interaction.

Advance directives and living wills.

PubMed Central

Stewart, K.; Bowker, L.

1998-01-01

Under certain circumstances, living wills or advance directives may carry legal force in the UK. This paper traces the development of advance directives, clarifies their current legal position and discusses potential problems with their use. Case histories are used to illustrate some of the common dilemmas which doctors may face. PMID:9640440

49 CFR 229.87 - Hand-operated switches.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 4 2013-10-01 2013-10-01 false Hand-operated switches. 229.87 Section 229.87....87 Hand-operated switches. All hand-operated switches carrying currents with a potential of more than... outside of the cover. Means shall be provided to show whether the switches are open or closed. Switches...

49 CFR 229.87 - Hand-operated switches.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 4 2012-10-01 2012-10-01 false Hand-operated switches. 229.87 Section 229.87....87 Hand-operated switches. All hand-operated switches carrying currents with a potential of more than... outside of the cover. Means shall be provided to show whether the switches are open or closed. Switches...

49 CFR 229.87 - Hand-operated switches.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 4 2011-10-01 2011-10-01 false Hand-operated switches. 229.87 Section 229.87....87 Hand-operated switches. All hand-operated switches carrying currents with a potential of more than... outside of the cover. Means shall be provided to show whether the switches are open or closed. Switches...

49 CFR 229.87 - Hand-operated switches.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 4 2014-10-01 2014-10-01 false Hand-operated switches. 229.87 Section 229.87....87 Hand-operated switches. All hand-operated switches carrying currents with a potential of more than... outside of the cover. Means shall be provided to show whether the switches are open or closed. Switches...

S(+)amphetamine induces a persistent leak in the human dopamine transporter: molecular stent hypothesis

PubMed Central

Rodriguez-Menchaca, Aldo A; Solis Jr, Ernesto; Cameron, Krasnodara; De Felice, Louis J

2012-01-01

BACKGROUND AND PURPOSE Wherever they are located, dopamine transporters (DATs) clear dopamine (DA) from the extracellular milieu to help regulate dopaminergic signalling. Exposure to amphetamine (AMPH) increases extracellular DA in the synaptic cleft, which has been ascribed to DAT reverse transport. Increased extracellular DA prolongs postsynaptic activity and reinforces abuse and hedonic behaviour. EXPERIMENTAL APPROACH Xenopus laevis oocytes expressing human (h) DAT were voltage-clamped and exposed to DA, R(-)AMPH, or S(+)AMPH. KEY RESULTS At -60mV, near neuronal resting potentials, S(+)AMPH induced a depolarizing current through hDAT, which after removing the drug, persisted for more than 30 min. This persistent leak in the absence of S(+)AMPH was in contrast to the currents induced by R(-)AMPH and DA, which returned to baseline immediately after their removal. Our data suggest that S(+)AMPH and Na+ carry the initial S(+)AMPH-induced current, whereas Na+ and Cl- carry the persistent leak current. We propose that the persistent current results from the internal action of S(+)AMPH on hDAT because the temporal effect was consistent with S(+)AMPH influx, and intracellular S(+)AMPH activated the effect. The persistent current was dependent on Na+ and was blocked by cocaine. Intracellular injection of S(+)AMPH also activated a DA-induced persistent leak current. CONCLUSIONS AND IMPLICATIONS We report a hitherto unknown action of S(+)AMPH on hDAT that potentially affects AMPH-induced DA release. We propose that internal S(+)AMPH acts as a molecular stent that holds the transporter open even after external S(+)AMPH is removed. Amphetamine-induced persistent leak currents are likely to influence dopaminergic signalling, DA release mechanisms, and amphetamine abuse. PMID:22014068

Gating currents from Kv7 channels carrying neuronal hyperexcitability mutations in the voltage-sensing domain.

PubMed

Miceli, Francesco; Vargas, Ernesto; Bezanilla, Francisco; Taglialatela, Maurizio

2012-03-21

Changes in voltage-dependent gating represent a common pathogenetic mechanism for genetically inherited channelopathies, such as benign familial neonatal seizures or peripheral nerve hyperexcitability caused by mutations in neuronal K(v)7.2 channels. Mutation-induced changes in channel voltage dependence are most often inferred from macroscopic current measurements, a technique unable to provide a detailed assessment of the structural rearrangements underlying channel gating behavior; by contrast, gating currents directly measure voltage-sensor displacement during voltage-dependent gating. In this work, we describe macroscopic and gating current measurements, together with molecular modeling and molecular-dynamics simulations, from channels carrying mutations responsible for benign familial neonatal seizures and/or peripheral nerve hyperexcitability; K(v)7.4 channels, highly related to K(v)7.2 channels both functionally and structurally, were used for these experiments. The data obtained showed that mutations affecting charged residues located in the more distal portion of S(4) decrease the stability of the open state and the active voltage-sensing domain configuration but do not directly participate in voltage sensing, whereas mutations affecting a residue (R4) located more proximally in S(4) caused activation of gating-pore currents at depolarized potentials. These results reveal that distinct molecular mechanisms underlie the altered gating behavior of channels carrying disease-causing mutations at different voltage-sensing domain locations, thereby expanding our current view of the pathogenesis of neuronal hyperexcitability diseases. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Roebel assembled coated conductor cables (RACC): Ac-Losses and current carrying potential

NASA Astrophysics Data System (ADS)

Frank, A.; Heller, R.; Goldacker, W.; Kling, A.; Schmidt, C.

2008-02-01

Low ac-loss HTS cables for transport currents well above 1 kA are required for application in transformers and generators and are taken into consideration for future generations of fusion reactor coils. Coated conductors (CC) are suitable candidates for high field application at an operation temperature in the range 50-77 K. Ac-field applications require cables with low ac-losses and hence twisting of the individual strands. We solved this problem using the Roebel technique. Short lengths of Roebel bar cables were prepared from industrial DyBCO and YBCO-CC. Meander shaped tapes of 4 or 5 mm width with twist pitches of 123 or 127 mm were cut from the 10 or 12 mm wide CC tapes using a specially designed tool. Eleven or twelve of these strands were assembled to a cable. The electrical and mechanical connection of the tapes was achieved using a silver powder filled conductive epoxy resin. Ac-losses of a short sample in an external ac-field were measured as a function of frequency and field amplitude as well as the coupling current decay time constant. We discuss the results in terms of available theories and compare measured time constants in transverse field with measured coupling losses. Finally the potential of this cable type for ac-use is discussed with respect to ac-losses and current carrying capability.

Image Registration and Data Assimilation as a QUBO on the D-Wave Quantum Annealer

NASA Astrophysics Data System (ADS)

Pelissier, C.; LeMoigne, J.; Halem, M.; Simpson, D. G.; Clune, T.

2016-12-01

The advent of the commercially available D-Wave quantum annealer has for the first time allowed investigations of the potential of quantum effects to efficiently carry out certain numerical tasks. The D-Wave computer was initially promoted as a tool to solve Quadratic Unconstrained Binary Optimization problems (QUBOs), but currently, it is also being used to generate the Boltzmann statistics required to train Restricted Boltzmann machines (RBMs). We consider the potential of this new architecture in performing numerical computations required to estimate terrestrial carbon fluxes from OCO-2 observations using the LIS model. The use of RBMs is being investigated in this work, but here we focus on the D-Wave as a QUBO solver, and it's potential to carry out image registration and data assimilation. QUBOs are formulated for both problems and results generated using the D-Wave 2Xtm at the NAS supercomputing facility are presented.

Renewable Biochemical Methane Potential through Anaerobic Co-digestion from Selective Feed Stocks

NASA Astrophysics Data System (ADS)

Thara, K.; Navis Karthika, Ignatius; Dheenadayalan, M. S., Dr

2017-08-01

Biochemical Methane Potential (BMP) analysis provides a measure of the anaerobic biodegradability of a given substrate. BMP test is also used to evaluate the potential biogas (methane) production between various Co-digestion substrates. This test is also used to determine the amount of organic carbon in a given material that can be an aerobically converted to methane-Biogas. Studies were carried out for the production of biogas from the leather solid waste. Co-digestion (simultaneous digestion of two or more substrates) studies were carried out in batch reactor using the fleshing (a solid waste generated during the processing of raw hides or skins into finished leather) along with the fruit and vegetable waste at mesophilic condition 35° C). The anaerobic methanogenic seed sludge prepared separately followed by standard BMP test, which was used as the seed inoculums. Recent research on this topic is reviewed in this current paper.

Ionic currents in the guinea-pig taenia coli.

PubMed Central

Inomata, H; Kao, C Y

1976-01-01

Short segments of portions of taenia coli of the guinea-pig averaging 54 mum X 219 mum X ca. 200 mum have been studied by a double sucrose-gap voltage-clamp technique. 2. The average total capacitance was 0-4 muF, corresponding to approximately 10(4) cells, if a specific membrane capacitance of 3 muF/cm2 were assumed. 3. A significant resistance, averaging 11-4omega, was in series with the membrane, and seriously limited the accuracy of the voltage control possible. 4. On depolarization, an early transient inward current was followed by a late maintained outwary current. 5. The late current was carried mainly by K+, because its direction could be reversed if the preparation were first depolarized in isotonic K2SO4 and held back to the original resting potential. 6. After appropriate corrections for residual capacitative and leakage currents, a reversal potential for the late current (Eb) was determined to be 15-20 mV more negative than the natural resting potential. It was not affected by the amplitude or the duration of the activating voltage step, but could be changed by prolonged applications of holding current. 7. At rest, the ratio of PNa:PK was 0-16:1; for Eb it was 0-05:1. 8. The reversal potential for the transient early inward current (Ea) averaged 22 mV in Krebs-bicarbonate solution, but was shifted to about 35 mV when the late current was first suppressed with tetraethylammonium ion. The shift suggested that there was some overlap of the early and late currents. 9. Reduction of [Na+]o to 50% of normal, or replacement of all Na+ with dimethyldiethanol ammonium ion and choline ion, failed to cause any significant shifts in the reversal potential of the early current or reduce the magnitude of the early current. 10. Reduction of [Ca2+]o to 0-25 or 0-1 of the normal caused shifts of the Ea toward the negative and reductions in the early current. These changes can occur without changes in the maximum chord conductance of the early current, such as might happen in ordinary Krebs-bicarbonate solution, or in preparations which had been depolarized by prior treatment with isotonic K2SO4 and then held back to the original membrane voltage. 11. Increase of [Ca2+]o to 5 times normal increased the early inward current, and the maximum chord conductances of the early and late currents, but did not shift the Ea. 12. In preparations pretreated with TEA, increasing [Ca2+]o to 5 times normal shifted Ea toward 45 mV. 13. The various observations are interpreted to mean that the early current in the taenia coli is carried principally by influx of Ca2+, and not by Na+. PMID:1255524

Landauer-Büttiker Approach to Strongly Coupled Quantum Thermodynamics: Inside-Outside Duality of Entropy Evolution

NASA Astrophysics Data System (ADS)

Bruch, Anton; Lewenkopf, Caio; von Oppen, Felix

2018-03-01

We develop a Landauer-Büttiker theory of entropy evolution in time-dependent, strongly coupled electron systems. The formalism naturally avoids the problem of the system-bath distinction by defining the entropy current in the attached leads. This current can then be used to infer changes of the entropy of the system which we refer to as the inside-outside duality. We carry out this program in an adiabatic expansion up to first order beyond the quasistatic limit. When combined with particle and energy currents, as well as the work required to change an external potential, our formalism provides a full thermodynamic description, applicable to arbitrary noninteracting electron systems in contact with reservoirs. This provides a clear understanding of the relation between heat and entropy currents generated by time-dependent potentials and their connection to the occurring dissipation.

Aerodynamic Improvements to Cargo Carrying Rail Cars due to Roof Modifications

NASA Astrophysics Data System (ADS)

Condie, Robert; Maynes, Daniel

2012-11-01

The aerodynamic drag associated with the transport of commodities by rail is becoming increasingly important as the cost of diesel fuel increases. We provide an assessment of the influence of the roof structure on aerodynamic performance of two dissimilar rail cars, namely automobile carrying cars and coal carrying cars. Currently, the roof material for automobile carrying rail cars is corrugated steel, with the corrugation aligned perpendicular to the direction of travel. Coal cars are currently left uncovered for loading convenience and on the return leg from the power plant are empty. Aerodynamic drag data have been obtained through wind tunnel testing on 1/29 scale models to understand the savings that may be realized by judicious modification to the tops of both these car types. For the automobile-carrying cars, testing is performed for the corrugated and smooth roof configurations. This modification alone has the potential of reducing the car drag coefficient by nominally 25%. A broader study is performed for the coal cars, with data being acquired for coal filled models, empty models, and several cover prototype configurations. The results reveal that implementation of a cover may yield reductions in the aerodynamic drag for both coal filled (nominally 7%) and empty coal cars (nominally 30%).

Effects of Replacement of External Sodium Chloride with Sucrose on Membrane Currents of the Squid Giant Axon

PubMed Central

Adelman, William J.; Taylor, Robert E.

1964-01-01

It was observed that a reduction of the sodium chloride concentration in the external solution bathing a squid giant axon by replacement with sucrose resulted in marked decreases in the peak inward and steady-state outward currents through the axon membrane following a step decrease in membrane potential. These effects are quantitatively acounted for by the increase in series resistance resulting from the decreased conductivity of the sea water and the assumption that the sodium current obeys a relation of the form I = k1C1 - k2C2 where C1, C2 are internal and external ion activities and k1, k2 are independent of concentration. It is concluded that the potassium ion current is independent of the sodium concentration. That the inward current is carried by sodium ions has been confirmed. The electrical potential (or barrier height) profile in the membrane which drives sodium ions appears to be independent of sodium ion concentration or current. A specific effect of the sucrose on hyperpolarizing currents was observed and noted but not investigated in detail. PMID:14232131

BLOOD SUBSTITUTES: EVOLUTION FROM NON-CARRYING TO OXYGEN AND GAS CARRYING FLUIDS

PubMed Central

Cabrales, Pedro; Intaglietta, Marcos

2013-01-01

The development of oxygen (O2) carrying blood substitutes has evolved from the goal of replicating blood O2 transports properties to that of preserving microvascular and organ function, reducing the inherent or potential toxicity of the material used to carry O2, and treating pathologies initiated by anemia and hypoxia. Furthermore, the emphasis has shifted from blood replacement fluid to “O2 therapeutics” that restore tissue oxygenation to specific tissues regions. This review covers the different alternatives, potential and limitations of hemoglobin based O2 carriers (HBOCs) and perfluorocarbon based O2 carriers (PFCOCs), with emphasis on the physiological conditions disturbed in the situation that they will be used. It describes how concepts learned from plasma expanders without O2 carrying capacity can be applied to maintain O2 delivery and summarizes the microvascular responses due to HBOCs and PFCOCs. This review also presents alternative applications of HBOCs and PFCOCs namely: 1) How HBOC O2 affinity can be engineered to target O2 delivery to hypoxic tissues; and 2) How the high gas solubility of PFCOCs provides new opportunities for carrying, dissolving and delivering gases with biological activity. It is concluded that current blood substitutes development has amplified their applications horizon by devising therapeutic functions for oxygen carriers requiring limited O2 delivery capacity restoration. Conversely, full, blood-like O2 carrying capacity re-establishment awaits control of O2 carrier toxicity. PMID:23820271

Selective activation of heteromeric SK channels contributes to action potential repolarization in mouse atrial myocytes.

PubMed

Hancock, Jane M; Weatherall, Kate L; Choisy, Stéphanie C; James, Andrew F; Hancox, Jules C; Marrion, Neil V

2015-05-01

Activation of small conductance calcium-activated potassium (SK) channels is proposed to contribute to repolarization of the action potential in atrial myocytes. This role is controversial, as these cardiac SK channels appear to exhibit an uncharacteristic pharmacology. The objectives of this study were to resolve whether activation of SK channels contributes to atrial action potential repolarization and to determine the likely subunit composition of the channel. The effect of 2 SK channel inhibitors was assessed on outward current evoked in voltage clamp and on action potential duration in perforated patch and whole-cell current clamp recording from acutely isolated mouse atrial myocytes. The presence of SK channel subunits was assessed using immunocytochemistry. A significant component of outward current was reduced by the SK channel blockers apamin and UCL1684. Block by apamin displayed a sensitivity indicating that this current was carried by homomeric SK2 channels. Action potential duration was significantly prolonged by UCL1684, but not by apamin. This effect was accompanied by an increase in beat-to-beat variability and action potential triangulation. This pharmacology was matched by that of expressed heteromeric SK2-SK3 channels in HEK293 cells. Immunocytochemistry showed that atrial myocytes express both SK2 and SK3 channels with an overlapping expression pattern. Only proposed heteromeric SK2-SK3 channels are physiologically activated to contribute to action potential repolarization, which is indicated by the difference in pharmacology of evoked outward current and prolongation of atrial action potential duration. The effect of blocking this channel on the action potential suggests that SK channel inhibition during cardiac function has the potential to be proarrhythmic. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Cyclic nucleotides induce long-term augmentation of glutamate-activated chloride current in molluscan neurons.

PubMed

Bukanova, Julia V; Solntseva, Elena I; Skrebitsky, Vladimir G

2005-12-01

1. Literature data indicate that serotonin induces the long-term potentiation of glutamate (Glu) response in molluscan neurons. The aim of present work was to elucidate whether cyclic nucleotides can cause the same effect. 2. Experiments were carried out on isolated neurons of the edible snail (Helix pomatia) using a two-microelectrode voltage-clamp method. 3. In the majority of the cells examined, the application of Glu elicited a Cl- -current. The reversal potential (Er) of this current lied between -35 and -55 mV in different cells. 4. Picrotoxin, a blocker of Cl- -channels, suppressed this current equally on both sides of Er. Furosemide, an antagonist of both Cl- -channels and the Na+/K+/Cl- -cotransporter, had a dual effect on Glu-response: decrease in conductance, and shift of Er to negative potentials. 5. A short-term (2 min) cell treatment with 8-Br-cAMP or 8-Br-cGMP caused long-term (up to 30 min) change in Glu-response. At a holding potential of -60 mV, which was close to the resting level, an increase in Glu-activated inward current was observed. This potentiation seems to be related to the right shift of Er of Glu-activated Cl- -current rather than to the increase in conductance of Cl- -channels. The blocking effect of picrotoxin rested after 8-Br-cAMP treatment. 6. The change in the Cl- -homeostasis as a possible mechanism for the observed effect of cyclic nucleotides is discussed.

Inversion of Acoustic and Electromagnetic Recordings for Mapping Current Flow in Lightning Strikes

NASA Astrophysics Data System (ADS)

Anderson, J.; Johnson, J.; Arechiga, R. O.; Thomas, R. J.

2012-12-01

Acoustic recordings can be used to map current-carrying conduits in lightning strikes. Unlike stepped leaders, whose very high frequency (VHF) radio emissions have short (meter-scale) wavelengths and can be located by lightning-mapping arrays, current pulses emit longer (kilometer-scale) waves and cannot be mapped precisely by electromagnetic observations alone. While current pulses are constrained to conductive channels created by stepped leaders, these leaders often branch as they propagate, and most branches fail to carry current. Here, we present a method to use thunder recordings to map current pulses, and we apply it to acoustic and VHF data recorded in 2009 in the Magdalena mountains in central New Mexico, USA. Thunder is produced by rapid heating and expansion of the atmosphere along conductive channels in response to current flow, and therefore can be used to recover the geometry of the current-carrying channel. Toward this goal, we use VHF pulse maps to identify candidate conductive channels where we treat each channel as a superposition of finely-spaced acoustic point sources. We apply ray tracing in variable atmospheric structures to forward model the thunder that our microphone network would record for each candidate channel. Because multiple channels could potentially carry current, a non-linear inversion is performed to determine the acoustic source strength of each channel. For each combination of acoustic source strengths, synthetic thunder is modeled as a superposition of thunder signals produced by each channel, and a power envelope of this stack is then calculated. The inversion iteratively minimizes the misfit between power envelopes of recorded and modeled thunder. Because the atmospheric sound speed structure through which the waves propagate during these events is unknown, we repeat the procedure on many plausible atmospheres to find an optimal fit. We then determine the candidate channel, or channels, that minimizes residuals between synthetic and acoustic recordings. We demonstrate the usefulness of this method on both intracloud and cloud-to-ground strikes, and discuss factors affecting our ability to replicate recorded thunder.

Magnon diffusion theory for the spin Seebeck effect in ferromagnetic and antiferromagnetic insulators

NASA Astrophysics Data System (ADS)

Rezende, Sergio M.; Azevedo, Antonio; Rodríguez-Suárez, Roberto L.

2018-05-01

In magnetic insulators, spin currents are carried by the elementary excitations of the magnetization: spin waves or magnons. In simple ferromagnetic insulators there is only one magnon mode, while in two-sublattice antiferromagnetic insulators (AFIs) there are two modes, which carry spin currents in opposite directions. Here we present a theory for the diffusive magnonic spin current generated in a magnetic insulator layer by a thermal gradient in the spin Seebeck effect. We show that the formulations describing magnonic perturbation using a position-dependent chemical potential and those using a magnon accumulation are completely equivalent. Then we develop a drift–diffusion formulation for magnonic spin transport treating the magnon accumulation governed by the Boltzmann transport and diffusion equations and considering the full boundary conditions at the surfaces and interfaces of an AFI/normal metal bilayer. The theory is applied to the ferrimagnetic yttrium iron garnet and to the AFIs MnF2 and NiO, providing good quantitative agreement with experimental data.

Structuralism's Relevance in a Post-Structural Era: Re-Visiting Research on Multicultural Curricular Studies

ERIC Educational Resources Information Center

Shim, Jenna Min

2011-01-01

At the current historical juncture in which differences and inequalities are surfacing greater than ever in the world, societies, and schools, the main goal of this essay is to revisit the aspects of structuralism that can potentially contribute productively to understanding the invisible structures and forces that everyone carries (mostly…

Learner-To-Teacher Bullying as a Potential Factor Influencing Teachers' Mental Health

ERIC Educational Resources Information Center

Woudstra, Marit Helen; van Rensburg, Estie Janse; Visser, Maretha; Jordaan, Joyce

2018-01-01

Learner-to-teacher bullying is a focus area that has not been widely researched. The current research, underpinned by the ecosystemic paradigm, examined the proportion of teachers who reported exposure to bullying by learners. The study was carried out by using the Learner-to-teacher Bullying Questionnaire developed for this research.…

Permeation and block of TRPV1 channels by the cationic lidocaine derivative QX-314

PubMed Central

Puopolo, Michelino; Binshtok, Alexander M.; Yao, Gui-Lan; Oh, Seog Bae; Woolf, Clifford J.

2013-01-01

QX-314 (N-ethyl-lidocaine) is a cationic lidocaine derivative that blocks voltage-dependent sodium channels when applied internally to axons or neuronal cell bodies. Coapplication of external QX-314 with the transient receptor potential vanilloid 1 protein (TRPV1) agonist capsaicin produces long-lasting sodium channel inhibition in TRPV1-expressing neurons, suggestive of QX-314 entry into the neurons. We asked whether QX-314 entry occurs directly through TRPV1 channels or through a different pathway (e.g., pannexin channels) activated downstream of TRPV1 and whether QX-314 entry requires the phenomenon of “pore dilation” previously reported for TRPV1. With external solutions containing 10 or 20 mM QX-314 as the only cation, inward currents were activated by stimulation of both heterologously expressed and native TRPV1 channels in rat dorsal root ganglion neurons. QX-314-mediated inward current did not require pore dilation, as it activated within several seconds and in parallel with Cs-mediated outward current, with a reversal potential consistent with PQX-314/PCs = 0.12. QX-314-mediated current was no different when TRPV1 channels were expressed in C6 glioma cells, which lack expression of pannexin channels. Rapid addition of QX-314 to physiological external solutions produced instant partial inhibition of inward currents carried by sodium ions, suggesting that QX-314 is a permeant blocker. Maintained coapplication of QX-314 with capsaicin produced slowly developing reduction of outward currents carried by internal Cs, consistent with intracellular accumulation of QX-314 to concentrations of 50–100 μM. We conclude that QX-314 is directly permeant in the “standard” pore formed by TRPV1 channels and does not require either pore dilation or activation of additional downstream channels for entry. PMID:23303863

No-Drag Frame for Anomalous Chiral Fluid

DOE PAGES

Stephanov, Mikhail A.; Yee, Ho-Ung

2016-03-24

For an anomalous fluid carrying dissipationless chiral magnetic and/or vortical currents we show that there is a frame in which a stationary obstacle experiences no drag, but energy and charge currents do not vanish, resembling superfluidity. Unlike ordinary superfluid flow, the anomalous chiral currents can transport entropy in this frame. Moreover, we show that the second law of thermodynamics completely determines the amounts of these anomalous nondissipative currents in the “no-drag frame” as polynomials in temperature and chemical potential with known anomaly coefficients. These general results are illustrated and confirmed by a calculation in the chiral kinetic theory and inmore » the quark-gluon plasma at high temperature.« less

Calcium channels in solitary retinal ganglion cells from post-natal rat.

PubMed Central

Karschin, A; Lipton, S A

1989-01-01

1. Calcium currents from identified, post-natal retinal ganglion cell neurones from rat were studied with whole-cell and single-channel patch-clamp techniques. Na+ and K+ currents were suppressed with pharmacological agents, allowing isolation of current carried by either 10 mM-Ca2+ or Ba2- during whole-cell recordings. For cell-attached patch recordings, the recording pipette contained 96-110 mM-BaCl2 while the bath solution consisted of isotonic potassium aspartate in order to zero the neuronal membrane potential. 2. A transient component, present in approximately one-third of the whole-cell recordings resembles closely the T-type calcium current observed previously in other tissues. This component activates at low voltages (-40 to -50 mV from holding potentials negative to -80 mV), inactivates with a time constant of 10-30 ms at 35 degrees C, and is carried equally well by Ba2+ or Ca2+. In single-channel recordings small (8 pS) channels are observed whose aggregate microscopic kinetics correspond well to the macroscopic current obtained during whole-cell measurements. 3. During whole-cell recordings, a more prolonged component activates in all retinal ganglion cells at -40 to -20 mV from a holding potential of -90 mV. This component is substantially larger when equimolar Ba2+ replaces Ca2+ as the charge carrier, and is sensitive to the dihydropyridine agonist Bay K8644 (5 microM) and antagonists nifedipine (1-10 microM) and nimodipine (1-10 microM). Thus, the dihydropyridine pharmacology of this prolonged component resembles that of the L-type calcium current found in dorsal root ganglion neurones and in heart cells. Also reminiscent of the L-current, the prolonged component in this preparation is less inactivated at depolarized holding potentials (-60 to -40 mV) than the transient component. In cell-attached recordings, large (20 pS) channels are observed with activation properties similar to those of the prolonged portion of the whole-cell current. 4. omega-Conotoxin fraction GVIA (omega-CgTX VIA), a peptide from the venom of the snail Conus geographus, produces a readily reversible blockade of all components of the calcium current in these central mammalian neurones. This finding is in contrast to that of other preparations in which this toxin is responsible for an ephemeral block of T-current but a long-lasting block of other components of calcium current. 5. In summary, at least two components of calcium current with discrete underlying unitary events are present in post-natal retinal ganglion cells from rat. One component closely resembles the T or transient current observed in other cell types.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2559971

Carrying water may be a major contributor to disability from musculoskeletal disorders in low income countries: a cross-sectional survey in South Africa, Ghana and Vietnam.

PubMed

Geere, Jo-Anne; Bartram, Jamie; Bates, Laura; Danquah, Leslie; Evans, Barbara; Fisher, Michael B; Groce, Nora; Majuru, Batsirai; Mokoena, Michael M; Mukhola, Murembiwa S; Nguyen-Viet, Hung; Duc, Phuc Pham; Williams, Ashley Rhoderick; Schmidt, Wolf-Peter; Hunter, Paul R

2018-06-01

The Sustainable Development Goals include commitments to end poverty, and promote education for all, gender equality, the availability of water and decent work for all. An important constraint is the fact that each day, many millions of women and children, and much less frequently men, carry their household's water home from off-plot sources. The burden of fetching water exacerbates gender inequality by keeping women out of education and paid employment. Despite speculation about the potential health impacts of fetching water, there is very little empirical evidence. We report the first large study of the health impacts of carrying water on women and children. A cross-sectional survey was conducted in South Africa, Ghana and Vietnam during 2012. It investigated water carrying methods and health status. Because areas of self-reported pain were correlated we undertook factor analysis of sites of reported pain, to interpret patterns of pain reporting. Regression analysis using Generalised Estimating Equations (GEE) investigated water carrying as a risk factor for general health and self-reported pain. People who previously carried water had increased relative risk of reporting pain in the hands (risk ratio RR 3.62, 95% confidence interval CI 1.34 to 9.75) and upper back (RR 2.27, 95% CI 1.17 to 4.40), as did people who currently carry water (RR hand pain 3.11, 95% CI 1.34 to 7.23; RR upper back pain 2.16, 95% CI 1.25 to 3.73). The factor analysis results indicate that factor 1, 'axial compression', which is correlated with pain in the head and upper back, chest/ribs, hands, feet and abdomen/stomach, is associated with currently (0.30, 95% CI 0.17 to 0.43) or previously (0.21, 95% CI 0.01 to 0.42) carrying water. Factor 2, 'soft tissue strain', which is correlated with pain in the neck, shoulders/arms, lower back and hips/pelvis or legs, is marginally negatively associated with currently (-0.18, 95% CI -0.32 to -0.04) carrying water. The factor 'axial compression' was more strongly associated with carrying water containers on the head. Participants who reported a history of current or past water carrying more frequently reported pain in locations most likely to be associated with sustained spinal axial compression in the cervical region. Given the fact that cervical spinal conditions are globally one of the more common causes of disability, our findings suggest that water carrying, especially by head loading is a major contributing factor in musculoskeletal disease burden in low income countries. Our findings support the proposed indicator for monitoring SDG6.1: "Percentage of population using safely managed drinking water services at home."

Transient sodium current at subthreshold voltages: activation by EPSP waveforms

PubMed Central

Carter, Brett C.; Giessel, Andrew J.; Sabatini, Bernardo L.; Bean, Bruce P.

2012-01-01

Summary Tetrodotoxin (TTX)-sensitive sodium channels carry large transient currents during action potentials and also “persistent” sodium current, a non-inactivating TTX-sensitive current present at subthreshold voltages. We examined gating of subthreshold sodium current in dissociated cerebellar Purkinje neurons and hippocampal CA1 neurons, studied at 37 °C with near-physiological ionic conditions. Unexpectedly, in both cell types small voltage steps at subthreshold voltages activated a substantial component of transient sodium current as well as persistent current. Subthreshold EPSP-like waveforms also activated a large component of transient sodium current, but IPSP-like waveforms engaged primarily persistent sodium current with only a small additional transient component. Activation of transient as well as persistent sodium current at subthreshold voltages produces amplification of EPSPs that is sensitive to the rate of depolarization and can help account for the dependence of spike threshold on depolarization rate, as previously observed in vivo. PMID:22998875

A combined vector potential-scalar potential method for FE computation of 3D magnetic fields in electrical devices with iron cores

NASA Technical Reports Server (NTRS)

Wang, R.; Demerdash, N. A.

1991-01-01

A method of combined use of magnetic vector potential based finite-element (FE) formulations and magnetic scalar potential (MSP) based formulations for computation of three-dimensional magnetostatic fields is introduced. In this method, the curl-component of the magnetic field intensity is computed by a reduced magnetic vector potential. This field intensity forms the basic of a forcing function for a global magnetic scalar potential solution over the entire volume of the region. This method allows one to include iron portions sandwiched in between conductors within partitioned current-carrying subregions. The method is most suited for large-scale global-type 3-D magnetostatic field computations in electrical devices, and in particular rotating electric machinery.

High sensitivity of spontaneous spike frequency to sodium leak current in a Lymnaea pacemaker neuron.

PubMed

Lu, T Z; Kostelecki, W; Sun, C L F; Dong, N; Pérez Velázquez, J L; Feng, Z-P

2016-12-01

The spontaneous rhythmic firing of action potentials in pacemaker neurons depends on the biophysical properties of voltage-gated ion channels and background leak currents. The background leak current includes a large K + and a small Na + component. We previously reported that a Na + -leak current via U-type channels is required to generate spontaneous action potential firing in the identified respiratory pacemaker neuron, RPeD1, in the freshwater pond snail Lymnaea stagnalis. We further investigated the functional significance of the background Na + current in rhythmic spiking of RPeD1 neurons. Whole-cell patch-clamp recording and computational modeling approaches were carried out in isolated RPeD1 neurons. The whole-cell current of the major ion channel components in RPeD1 neurons were characterized, and a conductance-based computational model of the rhythmic pacemaker activity was simulated with the experimental measurements. We found that the spiking rate is more sensitive to changes in the Na + leak current as compared to the K + leak current, suggesting a robust function of Na + leak current in regulating spontaneous neuronal firing activity. Our study provides new insight into our current understanding of the role of Na + leak current in intrinsic properties of pacemaker neurons. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Measurement of vehicle potential using a mother-daughter tethered rocket

NASA Technical Reports Server (NTRS)

Williamson, P. R.; Denig, W. F.; Banks, P. M.; Raitt, W. J.; Kawashima, N.; Hirao, K.; Oyama, K. I.; Sasaki, S.

1982-01-01

The equipment, experimental design, and results of mother-daughter tethered probes for measuring the potential of a spacecraft are described. The object was to inject a probe into the ionosphere by rocket and then lower an impedance voltage monitor-equipped section of the probe by means of a highly insulated wire. The mother probe, also carrying voltage monitors, would inject charges into the plasma that would be measured at both ends of the tether. Instrumentation on the daughter probe included voltage current monitors and a Langmuir probe, while the mother payload also carried a charge probe, floating probe, a Langmuir probe, and an impedance probe. The first launch was from Japan in 1980, and operations confirmed that Langmuir probes with area ratios less than 400:1 can produce changes in the vehicle potential if probe voltages of more than 10 V are applied in the collection mode. A ratio of 200:1 was sufficient for the daughter probe with voltages of 5 V. The experiment is concluded to verify the tethered probe method of measuring vehicle potential.

Current induced perpendicular-magnetic-anisotropy racetrack memory with magnetic field assistance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Y.; Klein, J.-O.; Chappert, C.

2014-01-20

High current density is indispensable to shift domain walls (DWs) in magnetic nanowires, which limits the using of racetrack memory (RM) for low power and high density purposes. In this paper, we present perpendicular-magnetic-anisotropy (PMA) Co/Ni RM with global magnetic field assistance, which lowers the current density for DW motion. By using a compact model of PMA RM and 40 nm design kit, we perform mixed simulation to validate the functionality of this structure and analyze its density potential. Stochastic DW motion behavior has been taken into account and statistical Monte-Carlo simulations are carried out to evaluate its reliability performance.

Backflow and dissipation during the quantum decay of a metastable Fermi liquid

NASA Astrophysics Data System (ADS)

Iida, Kei

1999-02-01

The particle current in a metastable Fermi liquid against a first-order phase transition is calculated at zero temperature. During fluctuations of a droplet of the stable phase, in accordance with the conservation law, not only does an unperturbed current arise from the continuity at the boundary, but a backflow is induced by the density response. Quasiparticles carrying these currents are scattered by the boundary, yielding a dissipative backflow around the droplet. An energy of the hydrodynamic mass flow of the liquid and a friction force exerted on the droplet by the quasiparticles have been obtained in terms of a potential of their interaction with the droplet.

Current distribution in conducting nanowire networks

NASA Astrophysics Data System (ADS)

Kumar, Ankush; Vidhyadhiraja, N. S.; Kulkarni, Giridhar U.

2017-07-01

Conducting nanowire networks find diverse applications in solar cells, touch-screens, transparent heaters, sensors, and various related transparent conducting electrode (TCE) devices. The performances of these devices depend on effective resistance, transmittance, and local current distribution in these networks. Although, there have been rigorous studies addressing resistance and transmittance in TCE, not much attention is paid on studying the distribution of current. Present work addresses this compelling issue of understanding current distribution in TCE networks using analytical as well as Monte-Carlo approaches. We quantified the current carrying backbone region against isolated and dangling regions as a function of wire density (ranging from percolation threshold to many multiples of threshold) and compared the wired connectivity with those obtained from template-based methods. Further, the current distribution in the obtained backbone is studied using Kirchhoff's law, which reveals that a significant fraction of the backbone (which is believed to be an active current component) may not be active for end-to-end current transport due to the formation of intervening circular loops. The study shows that conducting wire based networks possess hot spots (extremely high current carrying regions) which can be potential sources of failure. The fraction of these hot spots is found to decrease with increase in wire density, while they are completely absent in template based networks. Thus, the present work discusses unexplored issues related to current distribution in conducting networks, which are necessary to choose the optimum network for best TCE applications.

Differential processing of social chemosignals obtained from potential partners in regards to gender and sexual orientation.

PubMed

Lübke, Katrin T; Hoenen, Matthias; Pause, Bettina M

2012-03-17

On an individual level, human body odors carry information about whether a person is an eligible mate. The current studies investigate if body odors also transmit information about individuals being potential partners in more general terms, namely in regards to gender and sexual orientation. In study 1, 14 gay and 14 heterosexual men were presented with body odors obtained from potential partners (gay male and heterosexual female body odors, respectively) and heterosexual male body odor as a control. In study 2, 14 lesbian and 14 heterosexual women were presented with lesbian female and heterosexual male body odors representing body odors of potential partners, and heterosexual female body odor as a control. Central nervous processing was analyzed using chemosensory event-related potentials and current source density analysis (64-channel EEG recording). Gay and heterosexual men responded with shorter P2 latencies to the body odors of their preferred sexual partners, and lesbian women responded with shorter P2 latencies to body odors of their preferred gender. In response to heterosexual male body odors, lesbian women displayed the most pronounced P3 amplitude, and distinct neuronal activation in medial frontal and parietal neocortical areas. A similar pattern of neuronal activation was observed in gay men when presented with heterosexual male body odor. Both the early processing advantage (P2) for desirable partners' body odors as well as the enhanced evaluative processing (P3, CSD) of undesirable partners' body odors suggest that human body odors indeed carry information about individuals being potential partners in terms of gender and sexual orientation. Copyright © 2011 Elsevier B.V. All rights reserved.

Computer-Mediated Online Language Learning Programmes vs. Tailor-Made Teaching Practices at University Level: A Foul Relationship or a Perfect Match?

ERIC Educational Resources Information Center

Brudermann, Cédric A.

2015-01-01

This paper explores the potential of digital learning environments to address current issues related to individualised instruction and the expansion of educational opportunities in English as a foreign language at university level. To do so, an applied linguistics-centred research endeavour was carried out. This reflection led to the…

Meeting the Mixed Methods Challenge of Integration in a Sociological Study of Structure and Agency

ERIC Educational Resources Information Center

Woolley, Claire M.

2009-01-01

Substantial integration of quantitative and qualitative data and findings in mixed methods studies is seldom seen, although maximizing the potential of the approach depends on this. An absence of exemplars has been identified as among a number of factors that currently impede integration in studies carried out by researchers using the approach.…

Gamification and Transmedia for Scientific Promotion and for Encouraging Scientific Careers in Adolescents

ERIC Educational Resources Information Center

Pérez-Manzano, Antonio; Almela-Baeza, Javier

2018-01-01

The current growth in gamification-based applications, and especially in what is known as Digital Game-based Learning (DGBL), is providing new opportunities with considerable educational potential. In the present study, we report on the results of the progress of a project for developing a setting for a gamified website carried out ad hoc,…

The study of the plasma jets of lead and silver simulating spent nuclear fuel components

NASA Astrophysics Data System (ADS)

Antonov, N. N.; Gavrikov, A. V.; Smirnov, V. P.; Liziakin, G. D.; Usmanov, R. A.; Vorona, N. A.; Timirkhanov, R. A.

2018-01-01

One of the tasks that must be solved to develop a spent nuclear fuel (SNF) plasma separation method is a creation of plasma source of substances simulating SNF components. Plasma of the diffuse arc discharge in a magnetic field with an incandescent cathode was considered in this paper, as such source. The discharge was initiated in a model substances vapor (lead and silver). Evaporation was carried out by crucible induction heating. Current- voltage characteristics of the discharge were obtained. Spectral analysis of the plasma jets radiation and double probe characteristics measurements in the area behind the anode were carried out. The minimum potential difference between the anode and cathode reached a value of about 7 V at current of about 1 A. When the potential difference in the discharge gap was close to 30 V (4.5 A) and 10 V (5.2 A) electron temperature in the plasma jet was 5-7 eV and 1-3 eV, respectively. Plasma density in jets took the value from 1011 cm-3 to 1012 cm-3. The obtained results indicate the possibility of using this type of discharge for the SNF plasma separation method approbation.

Epoxy coated reinforcement in bridge decks

NASA Astrophysics Data System (ADS)

Wills, J.

A review was conducted of methods relating to the use of epoxy coated reinforcing bars for bridge decks and their potential for use in the United Kingdom. A survey of work carried out in the USA was carried out and the analysis used in a preliminary cost study. The options of having either a hot rolled asphalt surfacing or a permanently exposed concrete wearing surface were considered. It was concluded that epoxy coating of the top steel in addition to current waterproofing practice would provide, at relatively little extra cost, additional assurance that the reinforcement would be adequately protected throughout the life of a bridge. Current design rules do not permit decks with permanently exposed concrete wearing surface without waterproofing. Epoxy coating may afford a means of introducing such decks but before a positive recommendation to delete waterproofing can be made further studies would have to be undertaken.

Properties of the cromakalim-induced potassium conductance in smooth muscle cells isolated from the rabbit portal vein.

PubMed Central

Beech, D. J.; Bolton, T. B.

1989-01-01

1. Single smooth muscle cells were isolated freshly from the rabbit portal vein and membrane currents were recorded by the whole-cell or excised patch configurations of the patch-clamp technique at room temperature. 2. Cromakalim (Ckm, 10 microM) induced a potassium current (ICkm) that showed no pronounced voltage-dependence and had low current noise. 3. This current, ICkm, was inhibited by (in order of potency): phencyclidine greater than quinidine greater than 4-aminopyridine greater than tetraethylammonium ions (TEA). These drugs inhibited the delayed rectifier current, IdK, which is activated by depolarization of the cell, with the same order of potency. 4. Large conductance calcium-activated potassium channels (LKCa) in isolated membrane patches were blocked by (in order of potency) quinidine greater than TEA approximately phencyclidine. 4-Aminopyridine was ineffective. A similar order of potency was found for block of spontaneous transient outward currents thought to represent bursts of openings of LKCa channels. 5. The low current noise of ICkm at positive potentials, and its susceptibility to inhibitors indicated that it was not carried by LKCa channels, and that it may be carried by channels which underlie IdK. It was observed that when ICkm was activated, IdK was reduced. However, in two experiments, ICkm was much more susceptible to glibenclamide than IdK; possible reasons for this are discussed. PMID:2590772

Combined magnetic vector-scalar potential finite element computation of 3D magnetic field and performance of modified Lundell alternators in Space Station applications. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Wang, Ren H.

1991-01-01

A method of combined use of magnetic vector potential (MVP) based finite element (FE) formulations and magnetic scalar potential (MSP) based FE formulations for computation of three-dimensional (3D) magnetostatic fields is developed. This combined MVP-MSP 3D-FE method leads to considerable reduction by nearly a factor of 3 in the number of unknowns in comparison to the number of unknowns which must be computed in global MVP based FE solutions. This method allows one to incorporate portions of iron cores sandwiched in between coils (conductors) in current-carrying regions. Thus, it greatly simplifies the geometries of current carrying regions (in comparison with the exclusive MSP based methods) in electric machinery applications. A unique feature of this approach is that the global MSP solution is single valued in nature, that is, no branch cut is needed. This is again a superiority over the exclusive MSP based methods. A Newton-Raphson procedure with a concept of an adaptive relaxation factor was developed and successfully used in solving the 3D-FE problem with magnetic material anisotropy and nonlinearity. Accordingly, this combined MVP-MSP 3D-FE method is most suited for solution of large scale global type magnetic field computations in rotating electric machinery with very complex magnetic circuit geometries, as well as nonlinear and anisotropic material properties.

Testing the Auroral Current-Voltage Relation in Multiple Arcs

NASA Astrophysics Data System (ADS)

Cameron, T. G.; Knudsen, D. J.; Cully, C. M.

2013-12-01

The well-known current-voltage relation within auroral inverted-V regions [Knight, Planet. Space Sci., 21, 741, 1973] predicts current carried by an auroral flux tube given the total potential drop between a plasma-sheet source region and the ionosphere. Numerous previous studies have tested this relation using spacecraft that traverse auroral arcs at low (ionospheric) or mid altitudes. Typically, the potential drop is estimated at the peak of the inverted-V, and field-aligned current is estimated from magnetometer data; statistical information is then gathered over many arc crossings that occur over a wide range of source conditions. In this study we use electron data from the FAST satellite to examine the current-voltage relation in multiple arc sets, in which the key source parameters (plasma sheet density and temperature) are presumed to be identical. We argue that this approach provides a more sensitive test of the Knight relation, and we seek to explain remaining variability with factors other than source variability. This study is supported by a grant from the Natural Sciences and Engineering Research Council of Canada.

Numerical modelling of electromagnetic loads on fusion device structures

NASA Astrophysics Data System (ADS)

Bettini, Paolo; Furno Palumbo, Maurizio; Specogna, Ruben

2014-03-01

In magnetic confinement fusion devices, during abnormal operations (disruptions) the plasma begins to move rapidly towards the vessel wall in a vertical displacement event (VDE), producing plasma current asymmetries, vessel eddy currents and open field line halo currents, each of which can exert potentially damaging forces upon the vessel and in-vessel components. This paper presents a methodology to estimate electromagnetic loads, on three-dimensional conductive structures surrounding the plasma, which arise from the interaction of halo-currents associated to VDEs with a magnetic field of the order of some Tesla needed for plasma confinement. Lorentz forces, calculated by complementary formulations, are used as constraining loads in a linear static structural analysis carried out on a detailed model of the mechanical structures of a representative machine.

Use of the Stockwell Transform in the Detection of P300 Evoked Potentials with Low-Cost Brain Sensors.

PubMed

Pérez-Vidal, Alan F; Garcia-Beltran, Carlos D; Martínez-Sibaja, Albino; Posada-Gómez, Rubén

2018-05-09

The evoked potential is a neuronal activity that originates when a stimulus is presented. To achieve its detection, various techniques of brain signal processing can be used. One of the most studied evoked potentials is the P300 brain wave, which usually appears between 300 and 500 ms after the stimulus. Currently, the detection of P300 evoked potentials is of great importance due to its unique properties that allow the development of applications such as spellers, lie detectors, and diagnosis of psychiatric disorders. The present study was developed to demonstrate the usefulness of the Stockwell transform in the process of identifying P300 evoked potentials using a low-cost electroencephalography (EEG) device with only two brain sensors. The acquisition of signals was carried out using the Emotiv EPOC ® device—a wireless EEG headset. In the feature extraction, the Stockwell transform was used to obtain time-frequency information. The algorithms of linear discriminant analysis and a support vector machine were used in the classification process. The experiments were carried out with 10 participants; men with an average age of 25.3 years in good health. In general, a good performance (75⁻92%) was obtained in identifying P300 evoked potentials.

Carrying water may be a major contributor to disability from musculoskeletal disorders in low income countries: a cross-sectional survey in South Africa, Ghana and Vietnam

PubMed Central

Geere, Jo-Anne; Bartram, Jamie; Bates, Laura; Danquah, Leslie; Evans, Barbara; Fisher, Michael B; Groce, Nora; Majuru, Batsirai; Mokoena, Michael M; Mukhola, Murembiwa S; Nguyen-Viet, Hung; Duc, Phuc Pham; Williams, Ashley Rhoderick; Schmidt, Wolf-Peter; Hunter, Paul R

2018-01-01

Background The Sustainable Development Goals include commitments to end poverty, and promote education for all, gender equality, the availability of water and decent work for all. An important constraint is the fact that each day, many millions of women and children, and much less frequently men, carry their household’s water home from off-plot sources. The burden of fetching water exacerbates gender inequality by keeping women out of education and paid employment. Despite speculation about the potential health impacts of fetching water, there is very little empirical evidence. We report the first large study of the health impacts of carrying water on women and children. Methods A cross-sectional survey was conducted in South Africa, Ghana and Vietnam during 2012. It investigated water carrying methods and health status. Because areas of self-reported pain were correlated we undertook factor analysis of sites of reported pain, to interpret patterns of pain reporting. Regression analysis using Generalised Estimating Equations (GEE) investigated water carrying as a risk factor for general health and self-reported pain. Results People who previously carried water had increased relative risk of reporting pain in the hands (risk ratio RR 3.62, 95% confidence interval CI 1.34 to 9.75) and upper back (RR 2.27, 95% CI 1.17 to 4.40), as did people who currently carry water (RR hand pain 3.11, 95% CI 1.34 to 7.23; RR upper back pain 2.16, 95% CI 1.25 to 3.73). The factor analysis results indicate that factor 1, ‘axial compression’, which is correlated with pain in the head and upper back, chest/ribs, hands, feet and abdomen/stomach, is associated with currently (0.30, 95% CI 0.17 to 0.43) or previously (0.21, 95% CI 0.01 to 0.42) carrying water. Factor 2, ‘soft tissue strain’, which is correlated with pain in the neck, shoulders/arms, lower back and hips/pelvis or legs, is marginally negatively associated with currently (-0.18, 95% CI -0.32 to -0.04) carrying water. The factor ‘axial compression’ was more strongly associated with carrying water containers on the head. Conclusions Participants who reported a history of current or past water carrying more frequently reported pain in locations most likely to be associated with sustained spinal axial compression in the cervical region. Given the fact that cervical spinal conditions are globally one of the more common causes of disability, our findings suggest that water carrying, especially by head loading is a major contributing factor in musculoskeletal disease burden in low income countries. Our findings support the proposed indicator for monitoring SDG6.1: “Percentage of population using safely managed drinking water services at home.” PMID:29497503

Augmented Currents of an HCN2 Variant in Patients with Febrile Seizure Syndromes

PubMed Central

Dibbens, Leanne M.; Reid, Christopher A.; Hodgson, Bree; Thomas, Evan A.; Phillips, Alison M.; Gazina, Elena; Cromer, Brett A.; Clarke, Alison L.; Baram, Tallie Z.; Scheffer, Ingrid E.; Berkovic, Samuel F.; Petrou, Steven

2012-01-01

The genetic architecture of common epilepsies is largely unknown. HCNs are excellent epilepsy candidate genes because of their fundamental neurophysiological roles. Screening in subjects with febrile seizures and genetic epilepsy with febrile seizures plus revealed that 2.4% carried a common triple proline deletion (delPPP) in HCN2 that was seen in only 0.2% of blood bank controls. Currents generated by mutant HCN2 channels were ~35% larger than those of controls; an effect revealed using automated electrophysiology and an appropriately powered sample size. This is the first association of HCN2 and familial epilepsy, demonstrating gain of function of HCN2 current as a potential contributor to polygenic epilepsy. PMID:20437590

In search of critically endangered species: the current situation of two tiny salamander species in the Neotropical mountains of Mexico.

PubMed

Sandoval-Comte, Adriana; Pineda, Eduardo; Aguilar-López, José L

2012-01-01

Worldwide, one in every three species of amphibian is endangered, 39 species have gone extinct in the last 500 years and another 130 species are suspected to have gone extinct in recent decades. Of the amphibians, salamanders have the highest portion of their species in one of the risk categories, even higher than the frogs. To date there have been few studies that have used recent field data to examine the status of populations of endangered salamanders. In this study we evaluate the current situation of two tiny salamanders, Parvimolge townsendi and Thorius pennatulus, both of which are distributed at intermediate elevations in the mountains of the northern Neotropics and are considered to be critically endangered; the first has been proposed as possibly extinct. By carrying out exhaustive surveys in both historical and potentially suitable sites for these two species, we evaluated their abundance and the characteristics of their habitats, and we estimated their potential geographic distribution. We visited 22 sites, investing 672 person-hours of sampling effort in the surveys, and found 201 P. townsendi salamanders in 11 sites and only 13 T. pennatulus salamanders in 5 sites. Both species were preferentially found in cloud forest fragments that were well conserved or only moderately transformed, and some of the salamanders were found in shade coffee plantations. The potential distribution area of both species is markedly fragmented and we estimate that it has decreased by more than 48%. The results of this study highlight the importance of carrying out exhaustive, systematic field surveys to obtain accurate information about the current situation of critically endangered species, and help us better understand the crisis that amphibians are facing worldwide.

Direct-Current Monitor With Flux-Reset Transformer Coupling

NASA Technical Reports Server (NTRS)

Canter, Stanley

1993-01-01

Circuit measures constant or slowly-varying unidirectional electrical current using flux-reset transformer coupling. Measurement nonintrusive in sense that no need for direct contact with wire that carries load current to be measured, and no need to install series resistive element in load-current path. Toroidal magnetic core wrapped with coil of wire placed around load-current-carrying wire, acts as transformer core, load-current-carrying wire acts as primary winding of transformer, and coil wrapped on core acts as secondary winding.

Comparison of sarcolemmal calcium channel current in rabbit and rat ventricular myocytes.

PubMed Central

Yuan, W; Ginsburg, K S; Bers, D M

1996-01-01

1. Fundamental properties of Ca2+ channel currents in rat and rabbit ventricular myocytes were measured using whole cell voltage clamp. 2. In rat, as compared with rabbit myocytes, Ca2+ channel current (ICa) was half-activated at about 10 mV more negative potential, decayed slower, was half-inactivated (in steady state) at about 5 mV more positive potential, and recovered faster from inactivation. 3. These features result in a larger steady-state window current in rat, and also suggest that under comparable voltage clamp conditions, including action potential (AP) clamp, more Ca2+ influx would be expected in rat myocytes. 4. Ca2+ channel current carried by Na+ and Cs+ in the absence of divalent ions (Ins) also activated at more negative potential and decayed more slowly in rat. 5. The reversal potential for Ins was 6 mV more positive in rabbit, consistent with a larger permeability ratio (PNa/PCs) in rabbit than in rat. ICa also reversed at slightly more positive potentials in rabbit (such that PCa/PCs might also be higher). 6. Ca2+ influx was calculated by integration of ICa evoked by voltage clamp pulses (either square pulses or pulses based on recorded rabbit or rat APs). For a given clamp waveform, the Ca2+ influx was up to 25% greater in rat, as predicted from the fundamental properties of ICa and Ins. 7. However, the longer duration of the AP in rabbit myocytes compensated for the difference in influx, such that the integrated Ca2+ influx via ICa in response to the species-appropriate waveform was about twice as large as that seen in rat. PMID:8799895

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

PubMed Central

Yamada-Hanff, Jason

2015-01-01

We used dynamic clamp and action potential clamp techniques to explore how currents carried by tetrodotoxin-sensitive sodium channels and HCN channels (Ih) regulate the behavior of CA1 pyramidal neurons at resting and subthreshold voltages. Recording from rat CA1 pyramidal neurons in hippocampal slices, we found that the apparent input resistance and membrane time constant were strongly affected by both conductances, with Ih acting to decrease apparent input resistance and time constant and sodium current acting to increase both. We found that both Ih and sodium current were active during subthreshold summation of artificial excitatory postsynaptic potentials (EPSPs) generated by dynamic clamp, with Ih dominating at less depolarized voltages and sodium current at more depolarized voltages. Subthreshold sodium current—which amplifies EPSPs—was most effectively recruited by rapid voltage changes, while Ih—which blunts EPSPs—was maximal for slow voltage changes. The combined effect is to selectively amplify rapid EPSPs. We did similar experiments in mouse CA1 pyramidal neurons, doing voltage-clamp experiments using experimental records of action potential firing of CA1 neurons previously recorded in awake, behaving animals as command voltages to quantify flow of Ih and sodium current at subthreshold voltages. Subthreshold sodium current was larger and subthreshold Ih was smaller in mouse neurons than in rat neurons. Overall, the results show opposing effects of subthreshold sodium current and Ih in regulating subthreshold behavior of CA1 neurons, with subthreshold sodium current prominent in both rat and mouse CA1 pyramidal neurons and additional regulation by Ih in rat neurons. PMID:26289465

The causes of dispersal and the cost of carry-over effects for an endangered bird in a dynamic wetland landscape.

PubMed

Robertson, Ellen P; Fletcher, Robert J; Austin, James D

2017-07-01

The decision to disperse or remain philopatric between breeding seasons has important implications for both ecology and evolution, including the potential for carry-over effects, where an individual's previous history affects its current performance. Carry-over effects are increasingly documented although underlying mechanisms remain unclear. Here we test for potential carry-over effects and their mechanisms by uniting hypotheses for the causes and consequences of habitat selection and dispersal across space and time. We linked hypotheses regarding different types of factors and information (environmental conditions, personal and public information) predicted to impact reproductive success and dispersal for an endangered, wetland-dependent bird, the snail kite (Rostrhamus sociabilis plumbeus). To do so, we coupled structural equation modelling with 20 years of mark-recapture and nesting data across the breeding range of this species to isolate potential direct and indirect effects of these factors. We found that water depth at nest sites explained subsequent emigration rates via an indirect path through the use of personal, not public, information. Importantly, we found that these dispersers tended to initiate nests later the following breeding season. This pattern explained a phenological mismatch of nesting with hydrological conditions, whereby immigrants tended to nest later, late nesters tended to experience lower water depths, higher nest failure occurred at lower water depths and higher nest failure explained subsequent breeding dispersal. These results identified a novel potential mechanism for carry-over effects: a phenological mismatch with environmental conditions (water depth) that occurred potentially due to time costs of dispersal. Our results also highlighted a substantial benefit of philopatry - earlier initiation of reproduction - which allows philopatric individuals to better coincide with environmental conditions that are beneficial for successful reproduction. These results have implications for our mechanistic understanding and prediction of carryover effects, and emphasize that local conservation strategies, such as water management, can explain future demography at distant sites connected through dispersal. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

Computational Models for Understanding of Structure, Function and Pharmacology of the Cardiac Potassium Channel Kv11.1 (hERG).

PubMed

Wacker, Soren; Noskov, Sergei Yu; Perissinotti, Laura L

2017-01-01

The rapid delayed rectifier current IKr is one of the major K+ currents involved in repolarization of the human cardiac action potential. Various inherited or drug-induced forms of the long QT syndrome (LQTS) in humans are linked to functional and structural modifications in the IKr conducting channels. IKr is carried by the potassium channel Kv11.1 encoded by the gene KCNH2 (commonly referred to as human ether-a-go-go-related gene or hERG) [1, 2]. The first necessary step for predicting emergent drug effects on the heart is determining and modeling the binding thermodynamics and kinetics of primary and major off-target drug interactions with subcellular targets. The bulk of drugs that target hERG channels are known to have complex interactions at the atomic scale. Accordingly, one of the goals for this review is to provide comprehensive guide in the universe of computational models aiming to refine our understanding of structure-function relations in Kv11.1 and its isoforms. The special emphasis is placed on the mapping of drug binding sites and tentative mechanisms of channel inhibition and activation by drugs. An overview over recent structural models and mapping of binding sites for blockers and activators of IKr current along with the discussion on agreements and discrepancies among different models is presented. There is an apparent reciprocity or feedback loop between drug binding and action potential of the cardiac myocytes. Thus one has to connect drug binding to a particular receptor so that its functional consequences impact on the action potential duration. The natural pathway is to develop multi-scale models that connect between receptor and cellular scales. The potential for such multi-scale model development is discussed through the lens of common gating models. Accordingly, the second part of this review covers an ongoing development of the kinetic models of gating transitions and cardiac ion currents carried by hERG channels with and without drug bound. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Impaired action potential initiation in GABAergic interneurons causes hyperexcitable networks in an epileptic mouse model carrying a human Na(V)1.1 mutation.

PubMed

Hedrich, Ulrike B S; Liautard, Camille; Kirschenbaum, Daniel; Pofahl, Martin; Lavigne, Jennifer; Liu, Yuanyuan; Theiss, Stephan; Slotta, Johannes; Escayg, Andrew; Dihné, Marcel; Beck, Heinz; Mantegazza, Massimo; Lerche, Holger

2014-11-05

Mutations in SCN1A and other ion channel genes can cause different epileptic phenotypes, but the precise mechanisms underlying the development of hyperexcitable networks are largely unknown. Here, we present a multisystem analysis of an SCN1A mouse model carrying the NaV1.1-R1648H mutation, which causes febrile seizures and epilepsy in humans. We found a ubiquitous hypoexcitability of interneurons in thalamus, cortex, and hippocampus, without detectable changes in excitatory neurons. Interestingly, somatic Na(+) channels in interneurons and persistent Na(+) currents were not significantly changed. Instead, the key mechanism of interneuron dysfunction was a deficit of action potential initiation at the axon initial segment that was identified by analyzing action potential firing. This deficit increased with the duration of firing periods, suggesting that increased slow inactivation, as recorded for recombinant mutated channels, could play an important role. The deficit in interneuron firing caused reduced action potential-driven inhibition of excitatory neurons as revealed by less frequent spontaneous but not miniature IPSCs. Multiple approaches indicated increased spontaneous thalamocortical and hippocampal network activity in mutant mice, as follows: (1) more synchronous and higher-frequency firing was recorded in primary neuronal cultures plated on multielectrode arrays; (2) thalamocortical slices examined by field potential recordings revealed spontaneous activities and pathological high-frequency oscillations; and (3) multineuron Ca(2+) imaging in hippocampal slices showed increased spontaneous neuronal activity. Thus, an interneuron-specific generalized defect in action potential initiation causes multisystem disinhibition and network hyperexcitability, which can well explain the occurrence of seizures in the studied mouse model and in patients carrying this mutation. Copyright © 2014 the authors 0270-6474/14/3414874-16$15.00/0.

Membrane currents underlying activity in frog sinus venosus

PubMed Central

Brown, Hilary F.; Giles, Wayne; Noble, Susan J.

1977-01-01

1. The spontaneous electrical activity of small strips of muscle from the sinus venosus region of the heart of Rana catesbeiana was investigated using the double sucrose gap technique. The voltage clamp was used to record the ionic currents underlying the pace-maker depolarization and the action potential. 2. The records of spontaneous electrical activity are very similar to those obtained from the sinus venosus using micro-electrodes. Moreover, the pace-maker activity is almost completely insensitive to tetrodotoxin (TTX) at 2·0 × 10-6 g/ml., which suggests that the pace-maker responses can be classified as primary, as opposed to follower pacing. 3. In response to short rectangular depolarizing voltage clamp pulses, only one inward current is activated. This current is almost completely insensitive to TTX but can be blocked by manganese ions. It appears, therefore, to be equivalent to the slow inward (Ca2+/Na+) current, Isi, of other cardiac tissues. The threshold for Isi is near to the maximum diastolic potential, indicating that it must be activated during the pace-maker depolarization. 4. Interruption of the normal pace-maker depolarization by rapid activation of the voltage clamp circuit reveals the time-dependent decay of outward current. This current reverses between -75 and -90 mV and, therefore, is probably carried mainly by potassium ions. 5. Outward current decay is not a simple exponential, and Hodgkin—Huxley analysis suggests that two distinct components of outward current may be present. One of these is activated in the potential range of the pace-maker depolarization and the other at more positive potentials. Both outward currents reach full, steady-state activation at about zero mV, i.e. within the `plateau' range of the sinus action potential. 6. These results are compared with other recently published voltage clamp data from the rabbit sino—atrial node. 7. A hypothesis for the generation of pace-maker activity is presented which involves (i) decay of outward current and (ii) activation of the slow inward current, Isi. PMID:303699

Topological States in Partially-PT -Symmetric Azimuthal Potentials

NASA Astrophysics Data System (ADS)

Kartashov, Yaroslav V.; Konotop, Vladimir V.; Torner, Lluis

2015-11-01

We introduce partially-parity-time (p PT ) -symmetric azimuthal potentials composed from individual PT -symmetric cells located on a ring, where two azimuthal directions are nonequivalent in a sense that in such potential excitations carrying topological dislocations exhibit different dynamics for different directions of energy circulation in the initial field distribution. Such nonconservative ratchetlike structures support rich families of stable vortex solitons in cubic nonlinear media, whose properties depend on the sign of the topological charge due to the nonequivalence of azimuthal directions. In contrast, oppositely charged vortex solitons remain equivalent in similar fully-P T -symmetric potentials. The vortex solitons in the p P T - and P T -symmetric potentials are shown to feature qualitatively different internal current distributions, which are described by different discrete rotation symmetries of the intensity profiles.

Evolution of Multiple Double Layer in Glow discharge and its inherent Properties

NASA Astrophysics Data System (ADS)

Alex, Prince; A, Saravanan; Sinha, Suraj

2016-10-01

Formation and evolution of multiple anodic double layers (MADLs) were experimentally studied in glow discharge plasma. The boundary condition for the existence of MADL was identified in terms of threshold bias and ambient working pressure. The MADL formation is accompanied by an explosive growth in anode current and consequent current-voltage characteristics follows a hysteresis loop. The analysis yield that stable MADLs is only observed when the control voltage V2 is between a certain critical values (Vq > νte MADL completely transforms to an intense high current carrying unstable anode glow. The floating potential analysis carried out using three axially positioned electrostatic probes shows a bipolar signature of DL with as the control parameter is varied. The floating potential analysis also shows that hysteresis arises due to the difference in magnitude of electric field required to align the space charges in the DL sheet at the control voltage changes forward and backward. The effect of pressure on MADL indicates that the MADL structure advances towards anode surface as the pressure is increases. The power dumped (W) in the MADL is estimated to decrease with increase in pressure while the same increase in the anode glow.

Effects of electric current on individual graphene oxide sheets combining in situ transmission electron microscopy and Raman spectroscopy

NASA Astrophysics Data System (ADS)

Martín, Gemma; Varea, Aïda; Cirera, Albert; Estradé, Sònia; Peiró, Francesca; Cornet, Albert

2018-07-01

Graphene oxide (GO) is currently the object of extensive research because of its potential use in mass production of graphene-based materials, but also due to its tunability which holds great promise for new nanoscale electronic devices and sensors. To obtain a better understanding of the role of GO in electronic nano-devices, the elucidation of the effects of electrical current on a single GO sheet is of great interest. In this work, in situ transmission electron microscopy is used to study the effects of the electrical current flow through single GO sheets using an scanning tunneling microscope holder. In order to correlate the applied current with the structural properties of GO, Raman spectroscopy is carried out and data analysis is used to obtain information regarding the reduction grade and the disorder degree of the GO sheets before and after the application of current.

Effects of electric current on individual graphene oxide sheets combining in situ transmission electron microscopy and Raman spectroscopy.

PubMed

Martín, Gemma; Varea, Aïda; Cirera, Albert; Estradé, Sònia; Peiró, Francesca; Cornet, Albert

2018-04-17

Graphene oxide (GO) is currently the object of extensive research because of its potential use in mass production of graphene-based materials, but also due to its tunability which holds great promise for new nanoscale electronic devices and sensors. To obtain a better understanding of the role of GO in electronic nano-devices, the elucidation of the effects of electrical current on a single GO sheet is of great interest. In this work, in situ transmission electron microscopy is used to study the effects of the electrical current flow through single GO sheets using an scanning tunneling microscope holder. In order to correlate the applied current with the structural properties of GO, Raman spectroscopy is carried out and data analysis is used to obtain information regarding the reduction grade and the disorder degree of the GO sheets before and after the application of current.

Advanced development of TFA-MOD coated conductors

NASA Astrophysics Data System (ADS)

Rupich, M. W.; Li, X.; Sathyamurthy, S.; Thieme, C.; Fleshler, S.

2011-11-01

American Superconductor is manufacturing 2G wire for initial commercial applications. The 2G wire properties satisfy the requirements for these initial projects; however, improvements in the critical current, field performance and cost are required to address the broad range of potential commercial and military applications. In order to meet the anticipated the performance and cost requirements, AMSC's R&D effort is focused on two major areas: (1) higher critical current and (2) enhanced flux pinning. AMSC's current 2G production wire, designed around a 0.8 μm thick YBCO layer deposited by a Metal Organic Deposition (MOD) process, carries a critical current in the range of 200-300 A/cm-w (77 K, sf). Achieving higher critical current requires increasing the thickness of the YBCO layer. This paper describes recent progress at AMSC on increasing the critical current of MOD-YBCO films using processes compatible with low-cost, high-rate manufacturing.

Current in nanojunctions: Effects of reservoir coupling

NASA Astrophysics Data System (ADS)

Yadalam, Hari Kumar; Harbola, Upendra

2018-07-01

We study the effect of system reservoir coupling on currents flowing through quantum junctions. We consider two simple double-quantum dot configurations coupled to two external fermionic reservoirs and study the net current flowing between the two reservoirs. The net current is partitioned into currents carried by the eigenstates of the system and by the coherences between the eigenstates induced due to coupling with the reservoirs. We find that current carried by populations is always positive whereas current carried by coherences are negative for large couplings. This results in a non-monotonic dependence of the net current on the coupling strength. We find that in certain cases, the net current can vanish at large couplings due to cancellation between currents carried by the eigenstates and by the coherences. These results provide new insights into the non-trivial role of system-reservoir couplings on electron transport through quantum dot junctions. In the presence of weak coulomb interactions, net current as a function of system reservoir coupling strength shows similar trends as for the non-interacting case.

Reactive power compensator

DOEpatents

El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.; Chen, Mingliang; Andexler, George; Huang, Tony

1992-01-01

A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation.

Reactive Power Compensator.

DOEpatents

El-Sharkawi, M.A.; Venkata, S.S.; Chen, M.; Andexler, G.; Huang, T.

1992-07-28

A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation. 26 figs.

Electrical voltages and resistances measured to inspect metallic cased wells and pipelines

DOEpatents

Vail, III, William Banning; Momii, Steven Thomas

2001-01-01

A cased well in the earth is electrically energized with A.C. current. Voltages are measured from three voltage measurement electrodes in electrical contact with the interior of the casing while the casing is electrically energized. In a measurement mode, A.C. current is conducted from a first current carrying electrode within the cased well to a remote second current carrying electrode located on the surface of the earth. In a calibration mode, current is passed from the first current carrying electrode to a third current carrying electrode located vertically at a different position within the cased well, where the three voltage measurement electrodes are located vertically in between the first and third current carrying electrodes. Voltages along the casing and resistances along the casing are measured to determine wall thickness and the location of any casing collars present so as to electrically inspect the casing. Similar methods are employed to energize a pipeline to measure the wall thickness of the pipeline and the location of pipe joints to electrically inspect the pipeline.

Electrical voltages and resistances measured to inspect metallic cased wells and pipelines

DOEpatents

Vail III, William Banning; Momii, Steven Thomas

2003-06-10

A cased well in the earth is electrically energized with A.C. current. Voltages are measured from three voltage measurement electrodes in electrical contact with the interior of the casing while the casing is electrically energized. In a measurement mode, A.C. current is conducted from a first current carrying electrode within the cased well to a remote second current carrying electrode located on the surface of the earth. In a calibration mode, current is passed from the first current carrying electrode to a third current carrying electrode located vertically at a different position within the cased well, where the three voltage measurement electrodes are located vertically in between the first and third current carrying electrodes. Voltages along the casing and resistances along the casing are measured to determine wall thickness and the location of any casing collars present so as to electrically inspect the casing. Similar methods are employed to energize a pipeline to measure the wall thickness of the pipeline and the location of pipe joints to electrically inspect the pipeline.

Integration of offshore wind farms through high voltage direct current networks

NASA Astrophysics Data System (ADS)

Livermore, Luke

The integration of offshore wind farms through Multi Terminal DC (MTDC) networks into the GB network was investigated. The ability of Voltage Source Converter (VSC) High Voltage Direct Current (HVDC) to damp Subsynchronous Resonance (SSR) and ride through onshore AC faults was studied. Due to increased levels of wind generation in Scotland, substantial onshore and offshore reinforcements to the GB transmission network are proposed. Possible inland reinforcements include the use of series compensation through fixed capacitors. This potentially can lead to SSR. Offshore reinforcements are proposed by two HVDC links. In addition to its primary functions of bulk power transmission, a HVDC link can be used to provide damping against SSR, and this function has been modelled. Simulation studies have been carried out in PSCAD. In addition, a real-time hardware-in-the-loop HVDC test rig has been used to implement and validate the proposed damping scheme on an experimental platform. When faults occur within AC onshore networks, offshore MTDC networks are vulnerable to DC overvoltages, potentially damaging the DC plant and cables. Power reduction and power dissipation control systems were investigated to ride through onshore AC faults. These methods do not require dedicated fast communication systems. Simulations and laboratory experiments are carried out to evaluate the control systems, with the results from the two platforms compared..

Stormwater quality management in rail transportation--past, present and future.

PubMed

Vo, Phuong Tram; Ngo, Huu Hao; Guo, Wenshan; Zhou, John L; Listowski, Andrzej; Du, Bin; Wei, Qin; Bui, Xuan Thanh

2015-04-15

Railways currently play an important role in sustainable transportation systems, owing to their substantial carrying capacity, environmental friendliness and land-saving advantages. Although total pollutant emissions from railway systems are far less than that of automobile vehicles, the pollution from railway operations should not be underestimated. To date, both scientific and practical papers dealing with stormwater management for rail tracks have solely focused on its drainage function. Unlike roadway transport, the potential of stormwater pollution from railway operations is currently mishandled. There have been very few studies into the impact of its operations on water quality. Hence, upon the realisation on the significance of nonpoint source pollution, stormwater management priorities should have been re-evaluated. This paper provides an examination of past and current practices of stormwater management in the railway industry, potential sources of stormwater pollution, obstacles faced in stormwater management and concludes with strategies for future management directions. Copyright © 2015 Elsevier B.V. All rights reserved.

Potentials of storing solar energy in the form of hydrogen for Egypt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdel, A.A.L.; Mohamed, M.A.

1989-01-01

A seemingly insatiable demand for energy characterizes Egypt as it approaches the end of the twentieth century. With the limited energy resources in the country, R and D to utilize renewable sources of energy is a must. This paper examines first the energy situation in Egypt and explores the potential of using solar energy in hydrogen production from water. Different schemes of dissociating water are reviewed next. Finally, research findings are reported for some experimental runs carried out for the electrolysis of water by solar energy, utilizing an eight-water photovoltaic cell (Telephonken type) to generate the DC current.

Validation of a triangular quantum well model for GaN-based HEMTs used in pH and dipole moment sensing

NASA Astrophysics Data System (ADS)

Rabbaa, S.; Stiens, J.

2012-11-01

Gallium nitride (GaN) is a relatively new semiconductor material that has the potential of replacing gallium arsenide (GaAs) in some of the more recent technological applications, for example chemical sensor applications. In this paper, we introduce a triangular quantum well model for an undoped AlGaN/GaN high electron mobility transistor (HEMT) structure used as a chemical and biological sensor for pH and dipole moment measurements of polar liquids. We have performed theoretical calculations related to the HEMT characteristics and we have compared them with experimental measurements carried out in many previous papers. These calculations include the current-voltage (I-V) characteristics of the device, the surface potential, the change in the drain current with the dipole moment and the drain current as a function of pH. The results exhibit good agreement with experimental measurements for different polar liquids and electrolyte solutions. It is also found that the drain current of the device exhibits a large linear variation with the dipole moment, and that the surface potential and the drain current depend strongly on the pH. Therefore, it can distinguish molecules with slightly different dipole moments and solutions with small variations in pH. The ability of the device to sense biomolecules (such as proteins) with very large dipole moments is investigated.

Analytical study of the performance of a geomembrane leak detection system.

PubMed

Lugli, Francesco; Mahler, Claudio Fernando

2016-05-01

The electrical detection of leaks in geomembranes is a method that allows identifying leakage of contaminants in lined facilities (e.g. sanitary landfills, pollutant ponds, etc.). The procedure in the field involves placing electrodes above and below the geomembrane, to generate an electrical current, which in turn engenders an electric potential distribution in the protective layer (generally a clayey soil). The electric potential will be greater in areas with higher current density, i.e. near leaks. In this study, we combined models from the literature to carry out a parametric analysis to identify the variables that most influence the amplitude of the electrical signals produced by leaks. The basic hypothesis is that the electrical conduction phenomena in a liner system could be depicted by a direct current circuit. After determining the value of the current at the leak, we calculated the electric potential distribution according to the model of Darilek and Laine. This enabled analysing the sensitivity of the parameters, which can be useful in the design of landfills and facilitate the location of leaks. This study showed that geomembranes with low electrical resistance (owing to low thickness, low resistivity, or extensive area) can hinder the leak detection process. In contrast, low thickness and high resistivity of the protection layer magnify the leak signal. © The Author(s) 2016.

Assessment of the footprint and carrying capacity of oil and gas well sites: the implications for limiting hydrocarbon resources.

NASA Astrophysics Data System (ADS)

Clancy, Sarah; Worrall, Fred; Davies, Richard; Gluyas, Jon

2017-04-01

The rapid growth of shale gas developments within the United States and the possibility of developments within Europe have raised concerns about the impact and potential environmental cost. In this study we estimated the likely physical footprint of well pads if shale gas or oil developments were to go forward in Europe and used these estimates to understand the impact upon existing infrastructure; the carrying capacity of the environment and how this may limit the proportion of resources that are accessible estimates. Conventional well pads in UK, The Netherlands and Poland were examined. For the existing UK conventional well pads the current minimum setback from a building for a currently producing well was measured. To assess the carrying capacity of the land surface, well pads, of the average well pad footprint, with recommended setbacks, were randomly placed into the licensed blocks covering the Bowland Shale, UK, and the extent to which they would interact or disrupt existing infrastructure assessed. The average conventional well site footprints were: 10800 m2 (1.08 ha) in the UK; 44600 m2 (4.46 ha) in The Netherlands; and 3000 m2 (0.30 ha) in Poland. The average area per well was: 541 m^2/well (0.05 ha/well) for the UK; 2870 m^2/well (0.29 ha/well) for Poland; and 6370 m^2/well (0.64 ha/well) for The Netherlands. Average access road lengths were: 230 m in the UK; 250 m in Poland; and 310 m in The Netherlands. The minimum setback from a building for a currently producing well was 21 m and 46 m from a house, though the mean setback was 329 and 447 m, respectively. When the surface and sub-surface footprints were considered our approach found that the carrying capacity of the sites and the restrictions from infrastructure over the currently licensed blocks covering the Bowland Shale (UK) was between 5 and 42%, with a mean of 26%. Using Cuadrilla's predicted recoverable reserves estimate of 8.5 x 10^11 m3 for the Bowland Basin, the carrying capacity of the surface and the likely maximum accessible gas reserves would be limited by the surface carrying capacity to 2.21 x 10^11 m^3.

Membrane Potentials of the Lobster Giant Axon Obtained by Use of the Sucrose-Gap Technique

PubMed Central

Julian, Fred J.; Moore, John W.; Goldman, David E.

1962-01-01

A method similar to the sucrose-gap technique introduced be Stäpfli is described for measuring membrane potential and current in singly lobster giant axons (diameter about 100 micra). The isotonic sucrose solution used to perfuse the gaps raises the external leakage resistance so that the recorded potential is only about 5 per cent less than the actual membrane potential. However, the resting potential of an axon in the sucrose-gap arrangement is increased 20 to 60 mv over that recorded by a conventional micropipette electrode when the entire axon is bathed in sea water. A complete explanation for this effect has not been discovered. The relation between resting potential and external potassium and sodium ion concentrations shows that potassium carries most of the current in a depolarized axon in the sucrose-gap arrangement, but that near the resting potential other ions make significant contributions. Lowering the external chloride concentration decreases the resting potential. Varying the concentration of the sucrose solution has little effect. A study of the impedance changes associated with the action potential shows that the membrane resistance decreases to a minimum at the peak of the spike and returns to near its initial value before repolarization is complete (a normal lobster giant axon action potential does not have an undershoot). Action potentials recorded simultaneously by the sucrose-gap technique and by micropipette electrodes are practically superposable. PMID:14452759

The function and molecular identity of inward rectifier channels in vestibular hair cells of the mouse inner ear

PubMed Central

Levin, Michaela E.

2012-01-01

Inner ear hair cells respond to mechanical stimuli with graded receptor potentials. These graded responses are modulated by a host of voltage-dependent currents that flow across the basolateral membrane. Here, we examine the molecular identity and the function of a class of voltage-dependent ion channels that carries the potassium-selective inward rectifier current known as IK1. IK1 has been identified in vestibular hair cells of various species, but its molecular composition and functional contributions remain obscure. We used quantitative RT-PCR to show that the inward rectifier gene, Kir2.1, is highly expressed in mouse utricle between embryonic day 15 and adulthood. We confirmed Kir2.1 protein expression in hair cells by immunolocalization. To examine the molecular composition of IK1, we recorded voltage-dependent currents from type II hair cells in response to 50-ms steps from −124 to −54 in 10-mV increments. Wild-type cells had rapidly activating inward currents with reversal potentials close to the K+ equilibrium potential and a whole-cell conductance of 4.8 ± 1.5 nS (n = 46). In utricle hair cells from Kir2.1-deficient (Kir2.1−/−) mice, IK1 was absent at all stages examined. To identify the functional contribution of Kir2.1, we recorded membrane responses in current-clamp mode. Hair cells from Kir2.1−/− mice had significantly (P < 0.001) more depolarized resting potentials and larger, slower membrane responses than those of wild-type cells. These data suggest that Kir2.1 is required for IK1 in type II utricle hair cells and contributes to hyperpolarized resting potentials and fast, small amplitude receptor potentials in response to current inputs, such as those evoked by hair bundle deflections. PMID:22496522

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

PubMed Central

Lu, Tom Z.; Feng, Zhong-Ping

2011-01-01

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

Current density characteristics in the studies of electromagnetically induced transparency in a GaAs/GaAlAs quantum well

NASA Astrophysics Data System (ADS)

Jayarubi, J.; Peter, A. John

2017-05-01

Confinement potential profiles due to conduction and valence bands are obtained in a Ga0.7Al0.3As/ GaAs/ Ga0.7Al0.3As using variation formulism. The free electron distribution is carried out. The confined energy eigenvalue and its corresponding wavefunctions of charge carriers are found using self-consistent method. The confined energies with the geometrical confinement are computed. The potentials due to charges are done by Poisson equation. The effects of dielectric mismatch between the GaAs and GaAlAs semiconductors are introduced in the effective potential expressions. Transfer matrix method is employed to obtain the respective energies. The transmission probability is obtained for a constant well size. The high current density characteristics as a function of applied voltage is investigated. This investigation on the electromagnetically induced transparency in the photonic material will exploit in fabricating novel nonlinear optical devices in future.

Therapeutic Potential of Curcumin for the Treatment of Brain Tumors

PubMed Central

Klinger, Neil V.

2016-01-01

Brain malignancies currently carry a poor prognosis despite the current multimodal standard of care that includes surgical resection and adjuvant chemotherapy and radiation. As new therapies are desperately needed, naturally occurring chemical compounds have been studied for their potential chemotherapeutic benefits and low toxicity profile. Curcumin, found in the rhizome of turmeric, has extensive therapeutic promise via its antioxidant, anti-inflammatory, and antiproliferative properties. Preclinical in vitro and in vivo data have shown it to be an effective treatment for brain tumors including glioblastoma multiforme. These effects are potentiated by curcumin's ability to induce G2/M cell cycle arrest, activation of apoptotic pathways, induction of autophagy, disruption of molecular signaling, inhibition of invasion, and metastasis and by increasing the efficacy of existing chemotherapeutics. Further, clinical data suggest that it has low toxicity in humans even at large doses. Curcumin is a promising nutraceutical compound that should be evaluated in clinical trials for the treatment of human brain tumors. PMID:27807473

Current sensor

DOEpatents

Yakymyshyn, Christopher Paul; Brubaker, Michael Allen; Yakymyshyn, Pamela Jane

2007-01-16

A current sensor is described that uses a plurality of magnetic field sensors positioned around a current carrying conductor. The sensor can be hinged to allow clamping to a conductor. The current sensor provides high measurement accuracy for both DC and AC currents, and is substantially immune to the effects of temperature, conductor position, nearby current carrying conductors and aging.

Forces on a current-carrying wire in a magnetic field: the macro-micro connection

NASA Astrophysics Data System (ADS)

Karam, R.; Kneubil, F. B.; Robilotta, M. R.

2017-09-01

The classic problem of determining the force on a current-carrying wire in a magnetic field is critically analysed. A common explanation found in many introductory textbooks is to represent the force on the wire as the sum of the forces on charge carriers. In this approach neither the nature of the forces involved nor their application points are fully discussed. In this paper we provide an alternative microscopic explanation that is suitable for introductory electromagnetism courses at university level. By considering the wire as a superposition of a positive and a negative cylindrical charge distributions, we show that the electrons are subject to both magnetic and electric forces, whereas the ionic lattice of the metal is dragged by an electric force. Furthermore, an analysis of the orders of magnitude involved in the problem gives counterintuitive results with valuable educational potential. We argue that this approach allows one to discuss different aspects of the physical knowledge, which are relevant in physics education.

(abstract) Two-Dimensional Surface Current in the Coastal Environment Using Vector Along-Track Interferometry

NASA Technical Reports Server (NTRS)

Rodriguez, Ernesto; Imel, David; Houshmand, Bijan; Carande, Richard

1994-01-01

The structure of surface currents in the coastal environment can be very complex as it is governed by a multitude of factors such as local bathymetry, sea state, etc. Knowledge of the structure of coastal currents is a key requirement in the ability to carry out safe maneuvers and landings in an unknown coastal situation. Furthermore, it is desirable to have the ability to obtain such information by remote sensing and in a timely manner. We present a remote sensing technique which has the potential to meet certain specific requisites. We will present a theoretical discussion of the measurement technique, then will demonstrate the technique using data previously acquired and compare the results against conventional along-track interferometric measurements.

Classical Hall Effect without Magnetic Field

NASA Astrophysics Data System (ADS)

Schade, Nicholas; Tao, Chiao-Yu; Schuster, David; Nagel, Sidney

We show that the sign and density of charge carriers in a material can be obtained without the presence of a magnetic field. This effect, analogous to the classical Hall effect, is due solely to the geometry of the current-carrying wire. When current flows, surface charges along the wire create small electric fields that direct the current to follow the path of the conductor. In a curved wire, the charge carriers must experience a centripetal force, which arises from an electric field perpendicular to the drift velocity. This electric field produces a potential difference between the sides of the wire that depends on the sign and density of the charge carriers. We experimentally investigate circuits made from superconductors or graphene to find evidence for this effect.

Estradiol-modified prolactin secretion independently of action potentials and Ca2+ and blockade of outward potassium currents in GH3 cells.

PubMed

Sánchez, Manuel; Suárez, Lorena; Cantabrana, Begoña; Bordallo, Javier

2017-01-01

Estrogens facilitate prolactin (PRL) secretion acting on pituitary cells. In GH 3 cells, estradiol induces acute action potentials and oscillations of intracellular Ca 2+ associated with the secretagogue function. Estradiol modulates several ion channels which may affect the action potential rate and the release of PRL in lactotroph cells, which might depend on its concentration. The aims were to characterize the acute effect of supraphysiological concentrations of estradiol on Ca 2+ and noninactivating K + currents and measure the effect on the spontaneous action potentials and PRL release in the somatolactotroph cell line, GH 3 . Electrophysiological studies were carried out by voltage- and current-clamp techniques and ELISA determination of PRL secretion. Pharmacological concentrations of estradiol (above 1 μM), without a latency period, blocked Ca 2+ channels and noninactivating K + currents, including the large-conductance voltage- and Ca 2+ -activated K + channels (BK), studied in whole-cell nystatin perforated and in excided inside-out patches of GH 3 and CHO cells, transiently transfected with the human α-pore forming subunit of BK. The effect on BK was contrary to the agonist effect associated with the regulatory β 1 -subunits of the BK, which GH 3 cells lack, but its transient transfection did not modify the noninactivating current blockade, suggesting a different mechanism of regulation. Estradiol, at the same concentration range, acutely decreased the frequency of action potentials, an expected effect as consequence of the Ca 2+ channel blockade. Despite this, PRL secretion initially increased, followed by a decrease in long-term incubations. This suggests that, in GH 3 cells, supraphysiological concentrations of estradiol modulating PRL secretion are partially independent of extracellular Ca 2+ influx.

Voltage-clamp analysis of membrane currents and excitation-contraction coupling in a crustacean muscle.

PubMed

Weiss, T; Erxleben, C; Rathmayer, W

2001-01-01

A single fibre preparation from the extensor muscle of a marine isopod crustacean is described which allows the analysis of membrane currents and simultaneously recorded contractions under two-electrode voltage-clamp conditions. We show that there are three main depolarisation-gated currents, two are outward and carried by K+, the third is an inward Ca2+ current, I(Ca). Normally, the K+ currents which can be isolated by using K+ channel blockers, mask I(Ca). I(Ca) activates at potentials more positive than -40 mV, is maximal around 0 mV, and shows strong inactivation at higher depolarisation. Inactivation depends on current rather than voltage. Ba2+, Sr2+ and Mg2+ can substitute for Ca2+. Ba2+ currents are about 80% larger than Ca2+ currents and inactivate little. The properties of I(Ca) characterise it as a high threshold L-type current. The outward current consists primarily of a fast, transient A current, I(K(A)) and a maintained, delayed rectifier current, I(K(V)). In some fibres, a small Ca2+-dependent K+ current is also present. I(K(A)) activates fast at depolarisation above -45 mV, shows pronounced inactivation and is almost completely inactivated at holding potentials more positive than -40 mV. I(K(A)) is half-maximally blocked by 70 microM 4-aminopyridine (4-AP), and 70 mM tetraethylammonium (TEA). I(K(V)) activates more slowly, at about -30 mV, and shows no inactivation. It is half-maximally blocked by 2 mM TEA but rather insensitive to 4-AP. Physiologically, the two K+ currents prevent all-or-nothing action potentials and determine the graded amplitude of active electrical responses and associated contractions. Tension development depends on and is correlated with depolarisation-induced Ca2+ influx mediated by I(Ca). The voltage dependence of peak tension corresponds directly to the voltage dependence of the integrated I(Ca). The threshold potential for contraction is at about -38 mV. Peak tension increases with increasing voltage steps, reaches maximum at around 0 mV, and declines with further depolarisation.

Operation of a swept Langmuir probe on a sounding rocket

NASA Astrophysics Data System (ADS)

Robertson, S. H.; Dickson, S.; Friedrich, M.; Sternovsky, Z.

2012-12-01

A swept cylindrical Langmuir probe was operated on two sounding rockets from ~ 60-120 km for the purpose of determining both the ambient electron density and the payload potential relative to the ambient plasma. The rockets were part of the CHAMPS (CHarge And mass of Meteoritic smoke ParticleS) rocket campaign and carried mass analyzers and various plasma probes to study charged meteoritic dust in the mesopause region. The payload potential is an important parameter for data interpretation. The rockets were launched in October of 2011 from Andøya Rocket Range, Norway. The launches were a few days apart with one taking place during the day and the other at night. The swept Langmuir probe data provided a current-voltage characteristic that had a distinct "knee" indicating the onset of electron collection; the probe voltage at this "knee" corresponds to the ambient plasma potential. The data indicate a payload potential of about -2 V to -1 V for both launches. The payload potential becomes less negative for altitudes above 80 km on the day launch due to photoemission. The probe current-voltage data are also compared with ion and electron density measurements from ion probes and Faraday rotation antennas, respectively. The data from the various instruments are in general agreement. Further consideration of the Langmuir probe performance shows that if the probe had been operated with feedback control to continuously collect electrons with a current of order 1 microamp, the probe potential would be an accurate, continuous indicator of the payload potential without the need for sweeping which could periodically alter the payload potential.

Separation of plutonium from lanthanum by electrolysis in LiCl KCl onto molten bismuth electrode

NASA Astrophysics Data System (ADS)

Serp, J.; Lefebvre, P.; Malmbeck, R.; Rebizant, J.; Vallet, P.; Glatz, J.-P.

2005-04-01

This work presents a study on the electroseparation of plutonium from lanthanum using molten bismuth electrodes in LiCl-KCl eutectic at 733 K. The reduction potentials of Pu3+ and La3+ ions were measured on a Bi thin film electrode using cyclic voltammetry (CV). A difference between the peak potentials for the formation of PuBi2 and LaBi2 of approximately 100 mV was found. Separation tests were then carried out using different current densities and salt phase compositions between a plutonium rod anode and an unstirred molten Bi cathode in order to evaluate the efficiency of an electrolytic separation process. At a current density of 12 mA/cm2/wt% (Pu3+), only Pu3+ ions are reduced into the molten Bi electrode, leaving La3+ ions in the salt melt. Similar results were found at two different Pu/La concentration ratios ([Pu]/[La] = 4 and 10). At a current density of 26 mA/cm2/wt% (Pu3+), co-reduction of Pu and La was observed as expected by the large negative potential of the Bi cathode during the separation test.

DE 1 observations of theta aurora plasma source regions and Birkeland current charge carriers

NASA Technical Reports Server (NTRS)

Menietti, J. D.; Burch, J. L.

1987-01-01

Detailed analyses of the DE 1 high-altitude plasma instrument electron and ion data have been performed for four passes during which theta auroras were observed. The data indicate that the theta auroras occur on what appear to be closed field lines with particle signatures and plasma parameters that are quite similar to those of the magnetospheric boundary plasma sheet. The field-aligned currents computed from particle fluxes in the energy range 18-13 keV above the theta auroras are observed to be generally downward on the dawnside of the arcs with a narrower region of larger (higher density) upward currents on the duskside of the arcs. These currents are carried predominantly by field-aligned beams of accelerated cold electrons. Of particualr interest in regions of upward field-aligned current are downward electron beams at energies less than the inferred potential drop above the spacecraft.

Hyperpolarization-activated current (I(h)) in vestibular calyx terminals: characterization and role in shaping postsynaptic events.

PubMed

Meredith, Frances L; Benke, Tim A; Rennie, Katherine J

2012-12-01

Calyx afferent terminals engulf the basolateral region of type I vestibular hair cells, and synaptic transmission across the vestibular type I hair cell/calyx is not well understood. Calyces express several ionic conductances, which may shape postsynaptic potentials. These include previously described tetrodotoxin-sensitive inward Na(+) currents, voltage-dependent outward K(+) currents and a K(Ca) current. Here, we characterize an inwardly rectifying conductance in gerbil semicircular canal calyx terminals (postnatal days 3-45), sensitive to voltage and to cyclic nucleotides. Using whole-cell patch clamp, we recorded from isolated calyx terminals still attached to their type I hair cells. A slowly activating, noninactivating current (I(h)) was seen with hyperpolarizing voltage steps negative to the resting potential. External Cs(+) (1-5 mM) and ZD7288 (100 μM) blocked the inward current by 97 and 83 %, respectively, confirming that I(h) was carried by hyperpolarization-activated, cyclic nucleotide gated channels. Mean half-activation voltage of I(h) was -123 mV, which shifted to -114 mV in the presence of cAMP. Activation of I(h) was well described with a third order exponential fit to the current (mean time constant of activation, τ, was 190 ms at -139 mV). Activation speeded up significantly (τ=136 and 127 ms, respectively) when intracellular cAMP and cGMP were present, suggesting that in vivo I(h) could be subject to efferent modulation via cyclic nucleotide-dependent mechanisms. In current clamp, hyperpolarizing current steps produced a time-dependent depolarizing sag followed by either a rebound afterdepolarization or an action potential. Spontaneous excitatory postsynaptic potentials (EPSPs) became larger and wider when I(h) was blocked with ZD7288. In a three-dimensional mathematical model of the calyx terminal based on Hodgkin-Huxley type ionic conductances, removal of I(h) similarly increased the EPSP, whereas cAMP slightly decreased simulated EPSP size and width.

Effect of oscillator strength and intermediate resonance on the performance of resonant phonon-based terahertz quantum cascade lasers

NASA Astrophysics Data System (ADS)

Fathololoumi, S.; Dupont, E.; Wasilewski, Z. R.; Chan, C. W. I.; Razavipour, S. G.; Laframboise, S. R.; Huang, Shengxi; Hu, Q.; Ban, D.; Liu, H. C.

2013-03-01

We experimentally investigated the effect of oscillator strength (radiative transition diagonality) on the performance of resonant phonon-based terahertz quantum cascade lasers that have been optimized using a simplified density matrix formalism. Our results show that the maximum lasing temperature (Tmax) is roughly independent of laser transition diagonality within the lasing frequency range of the devices under test (3.2-3.7 THz) when cavity loss is kept low. Furthermore, the threshold current can be lowered by employing more diagonal transition designs, which can effectively suppress parasitic leakage caused by intermediate resonance between the injection and the downstream extraction levels. Nevertheless, the current carrying capacity through the designed lasing channel in more diagonal designs may sacrifice even more, leading to electrical instability and, potentially, complete inhibition of the device's lasing operation. We propose a hypothesis based on electric-field domain formation and competition/switching of different current-carrying channels to explain observed electrical instability in devices with lower oscillator strengths. The study indicates that not only should designers maximize Tmax during device optimization but also they should always consider the risk of electrical instability in device operation.

Piperine production by endophytic fungus Colletotrichum gloeosporioides isolated from Piper nigrum.

PubMed

Chithra, S; Jasim, B; Sachidanandan, P; Jyothis, M; Radhakrishnan, E K

2014-03-15

Many endophytic fungi have been reported with the biosynthetic potential to produce same or similar metabolites present in host plants. The adaptations that might have acquired by these fungi as a result of the long-term association with their host plants can be the possible basis of their biosynthetic potential. The bioactive compounds originated from endophytes are currently explored for their potential applications in pharmaceutical, agriculture and food industries. Piper nigrum, a plant of the Piperaceae is very remarkable because of the presence of the alkaloid piperine. Piperine has been reported to have broad bioactive properties ranging from antimicrobial, antidepressant, anti-inflammatory, antioxidative to anticancer activities. Interestingly, piperine also plays a vital role in increasing the bioavailability of many drugs which again is a promising property. The current study was carried out to identify piperine producing endophytic fungus from Piper nigrum L. By screening various endophytic fungi, the isolate which was identified as member of Colletotrichum gloeosporioides was found to have the ability to form piperine and was confirmed by HPLC and LCMS. Considering the broad bioactive potential of piperine, the piperine producing fungi identified in the study can expect to have much industrial potential. Copyright © 2013 Elsevier GmbH. All rights reserved.

Gas Generators and Their Potential to Support Human-Scale HIADS (Hypersonic Inflatable Aerodynamic Decelerators)

NASA Technical Reports Server (NTRS)

Bodkin, Richard J.; Cheatwood, F. M.; Dillman, Robert A; Dinonno, John M.; Hughes, Stephen J.; Lucy, Melvin H.

2016-01-01

As HIAD technology progresses from 3-m diameter experimental scale to as large as 20-m diameter for human Mars entry, the mass penalties of carrying compressed gas has led the HIAD team to research current state-of-the-art gas generator approaches. Summarized below are several technologies identified in this survey, along with some of the pros and cons with respect to supporting large-scale HIAD applications.

Integral electrical characteristics and local plasma parameters of a RF ion thruster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masherov, P. E.; Riaby, V. A., E-mail: riaby2001@yahoo.com; Godyak, V. A.

2016-02-15

Comprehensive diagnostics has been carried out for a RF ion thruster based on inductively coupled plasma (ICP) source with an external flat antenna coil enhanced by ferrite core. The ICP was confined within a cylindrical chamber with low aspect ratio to minimize plasma loss to the chamber wall. Integral diagnostics of the ICP electrical parameters (RF power balance and coil current) allowed for evaluation of the antenna coils, matching networks, and eddy current loss and the true RF power deposited to plasma. Spatially resolved electron energy distribution functions, plasma density, electron temperatures, and plasma potentials were measured with movable Langmuirmore » probes.« less

Preliminary Development of a Multifunctional Hot Structure Heat Shield

NASA Technical Reports Server (NTRS)

Walker, Sandra P.; Daryabeigi, Kamran; Samareh, Jamshid A.; Armand, Sasan C.; Perino, Scott V

2014-01-01

Development of a Multifunctional Hot Structure Heat Shield concept has initiated with the goal to provide advanced technology with significant benefits compared to the current state of the art heat shield technology. The concept is unique in integrating the function of the thermal protection system with the primary load carrying structural component. An advanced carbon-carbon material system has been evaluated for the load carrying structure, which will be utilized on the outer surface of the heat shield, and thus will operate as a hot structure exposed to the severe aerodynamic heating associated with planetary entry. Flexible, highly efficient blanket insulation has been sized for use underneath the hot structure to maintain desired internal temperatures. The approach was to develop a preliminary design to demonstrate feasibility of the concept. The preliminary results indicate that the concept has the potential to save both mass and volume with significantly less recession compared to traditional heat shield designs, and thus provide potential to enable new planetary missions.

Electron acceleration in downward auroral field-aligned currents

NASA Astrophysics Data System (ADS)

Cran-McGreehin, Alexandra P.; Wright, Andrew N.

2005-10-01

The auroral downward field-aligned current is mainly carried by electrons accelerated up from the ionosphere into the magnetosphere along magnetic field lines. Current densities are typically of the order of a few μ Am-2, and the associated electrons are accelerated to energies of several hundred eV up to a few keV. This downward current has been modeled by Temerin and Carlson (1998) using an electron fluid. This paper extends that model by describing the electron populations via distribution functions and modeling all of the F region. We assume a given ion density profile, and invoke quasi-neutrality to solve for the potential along the field line. Several important locations and quantities emerge from this model: the ionospheric trapping point, below which the ionospheric population is trapped by an ambipolar electric field; the location of maximum E∥, of the order of a few mVm-1, which lies earthward of the B/n peak; the acceleration region, located around the B/n peak, which normally extends between altitudes of 500 and 3000 km; and the total potential increase along the field line, of the order of a few hundred V up to several kV. The B/n peak is found to be the central factor determining the altitude and magnitude of the accelerating potential required. Indeed, the total potential drop is found to depend solely on the equilibrium properties in the immediate vicinity of the B/n peak.

Modulation of desensitization at glutamate receptors in isolated crucian carp horizontal cells by concanavalin A, cyclothiazide, aniracetam and PEPA.

PubMed

Shen, Y; Lu, T; Yang, X L

1999-03-01

In horizontal cells freshly dissociated from crucian carp (Carassius auratus) retina, we examined the effects of modulators of glutamate receptor desensitization, concanavalin A, cyclothiazide, aniracetam and 4-[2-(phenylsulfonylamino)ethylthio]-2,6-difluoro-phenoxyacetam ide (PEPA), on responses to rapid application of glutamate and kainate, using whole-cell voltage-clamp techniques. Incubation of concanavalin A suppressed the peak response but weakly potentiated the equilibrium response of horizontal cells to glutamate. Cyclothiazide blocked glutamate-induced desensitization in a dose-dependent manner, which resulted in a steady increase of the equilibrium current. The concentration of cyclothiazide causing a half-maximal potentiation for the equilibrium response was 85 microM. Furthermore, cyclothiazide shifted the dose-response relationship of the equilibrium current to the right, but slightly suppressed the kainate-induced sustained current. These effects of concanavalin A and cyclothiazide are consistent with the supposition that glutamate receptors of carp horizontal cells may be an alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)-preferring subtype. In order to further characterize the AMPA receptors of horizontal cells, modulation by aniracetam and PEPA of glutamate- and kainate-induced currents was studied. Aniracetam, a preferential modulator of flop variants of AMPA receptors, considerably blocked desensitization of glutamate-induced currents, but only slightly potentiated kainate-induced currents. It was further found that PEPA, a flop-preferring allosteric modulator of AMPA receptor desensitization, slightly suppressed the peak current, while it dramatically potentiated the equilibrium current induced by glutamate in a dose-dependent manner. PEPA was much potent than aniracetam at these receptors and showed the effect on glutamate-induced desensitization even at a concentration as low as 3 microM. PEPA also potentiated non-desensitizing currents induced by kainate, but with much less extent. These modulatory effects of concanavalin A, cyclothiazide, aniracetam and PEPA on AMPA receptors in carp horizontal cells were rather similar to those obtained at AMPA receptors assembled from flop variants expressed in Xenopus oocyte and HEK cell. Consequently, we speculate that the AMPA receptor on carp horizontal cells may predominantly carry the flop splice variants.

Temperature compensated and self-calibrated current sensor using reference current

DOEpatents

Yakymyshyn, Christopher Paul [Seminole, FL; Brubaker, Michael Allen [Loveland, CO; Yakymyshyn, Pamela Jane [Seminole, FL

2008-01-22

A method is described to provide temperature compensation and self-calibration of a current sensor based on a plurality of magnetic field sensors positioned around a current carrying conductor. A reference electrical current carried by a conductor positioned within the sensing window of the current sensor is used to correct variations in the output signal due to temperature variations and aging.

Prescribers' expectations and barriers to electronic prescribing of controlled substances

PubMed Central

Kim, Meelee; McDonald, Ann; Kreiner, Peter; Kelleher, Stephen J; Blackman, Michael B; Kaufman, Peter N; Carrow, Grant M

2011-01-01

Objective To better understand barriers associated with the adoption and use of electronic prescribing of controlled substances (EPCS), a practice recently established by US Drug Enforcement Administration regulation. Materials and methods Prescribers of controlled substances affiliated with a regional health system were surveyed regarding current electronic prescribing (e-prescribing) activities, current prescribing of controlled substances, and expectations and barriers to the adoption of EPCS. Results 246 prescribers (response rate of 64%) represented a range of medical specialties, with 43.1% of these prescribers current users of e-prescribing for non-controlled substances. Reported issues with controlled substances included errors, pharmacy call-backs, and diversion; most prescribers expected EPCS to address many of these problems, specifically reduce medical errors, improve work flow and efficiency of practice, help identify prescription diversion or misuse, and improve patient treatment management. Prescribers expected, however, that it would be disruptive to practice, and over one-third of respondents reported that carrying a security authentication token at all times would be so burdensome as to discourage adoption. Discussion Although adoption of e-prescribing has been shown to dramatically reduce medication errors, challenges to efficient processes and errors still persist from the perspective of the prescriber, that may interfere with the adoption of EPCS. Most prescribers regarded EPCS security measures as a small or moderate inconvenience (other than carrying a security token), with advantages outweighing the burden. Conclusion Prescribers are optimistic about the potential for EPCS to improve practice, but view certain security measures as a burden and potential barrier. PMID:21946239

The study of lead vapor ionization in discharge with a hot cathode and efficiency of its deposition on the substrates applied for plasma separation method

NASA Astrophysics Data System (ADS)

Antonov, N. N.; Samokhin, A. A.; Zhabin, S. N.; Gavrikov, A. V.; Smirnov, V. P.

2016-11-01

Spent nuclear fuel plasma separation method approbation implies the use of model substances. Thus it is necessary to solve the problem of material conversion into a cold plasma flow, as well as the problem of deposition on collectors. For this purpose, we carried out a kinetic and hydrodynamic simulation of the discharge with hot cathode in the lead vapor (lead vapor was injected into the interelectrode gap). Dependencies of the ionization efficiency, electrostatic potential distribution, density distribution of ions and electrons in the discharge gap on the discharge current density and the model substance vapor concentration were obtained. The simulation results show that at discharge current density of about 3.5 A/cm2 and the lead vapor concentration of 2 × 1012 cm-3, the ionization efficiency is close to 60%. Experimental research of the discharge with a hot cathode in the lead vapor was carried out. We also carried out the research of the Pb condensation coefficients on various substrates. For experimental data analysis the numerical model based on Monte Carlo method was used. The research results show that deposition coefficients at medium temperatures of substrates near 70 °C do not drop lower than 75%.

Mutual coupling effects in antenna arrays, volume 1

NASA Technical Reports Server (NTRS)

Collin, R. E.

1986-01-01

Mutual coupling between rectangular apertures in a finite antenna array, in an infinite ground plane, is analyzed using the vector potential approach. The method of moments is used to solve the equations that result from setting the tangential magnetic fields across each aperture equal. The approximation uses a set of vector potential model functions to solve for equivalent magnetic currents. A computer program was written to carry out this analysis and the resulting currents were used to determine the co- and cross-polarized far zone radiation patterns. Numerical results for various arrays using several modes in the approximation are presented. Results for one and two aperture arrays are compared against published data to check on the agreement of this model with previous work. Computer derived results are also compared against experimental results to test the accuracy of the model. These tests of the accuracy of the program showed that it yields valid data.

[Prediction of intra-abdominal hypertension risk in patients with acute colonic obstruction under epidural analgesia].

PubMed

Stakanov, A V; Potseluev, E A; Musaeva, T S

2013-01-01

Purpose of the study was to identify prediction possibility of direct current potential level for intra-abdominal hypertension risk in patients with acute colonic obstruction under preoperative epidural analgesia. Prospective analysis of the preoperative period was carried out in 140 patients with acute colonic obstruction caused by colon cancer. Relations between preoperative level of permanent capacity and risk of intra-abdominal hypertension was identified Direct current potential level is an independent predictor of intra-abdominal hypertension. Diagnostic significance increases from first to fifth hour of preoperative period according to AUROC data from 0.821 to 0.905 and calibration 6.9 (p > 0.37) and 4.7 (p > 0.54) by Hosmer-Lemeshou criteria. The use of epidural analgesia in the complex intensive preoperative preparation is pathogenically justified. It reduces intra-abdominal hypertension in patients with acute colonic obstruction.

Multiple pole electromagnetic propulsion system with separated ballistic guidance and electrical current contact surfaces

DOEpatents

Sims, Jr., James R.

2008-07-15

An electromagnetic propulsion system is disclosed having separate rails for ballistic guidance and for carrying current. In this system, one or more pairs of ballistic guidance rails are provided, with each ballistic guidance rail having a pair of current carrying rails joined to it to form a combined rail. Each combined rail is separated electrically from adjacent combined rails by electrically insulating blocks. Each of the current carrying rails in a given combined rail pair have the same electrical polarity, and the polarities alternate between adjacent combined rails. Armatures contact current carrying rails to complete the circuit to generate the accelerating Lorentz force on the armatures. Bore riders on the sabot and/or projectile are in contact with the ballistic guide rails. Separation of the current carrying and ballistic guidance functions increases resistance of the system to rail movement and bending, as well as reduced wear/damage to the rails. In further embodiments, a circumferential over wrap providing compressive force on the rails further increases resistance of the system to rail movement and bending.

Electron currents associated with an auroral band

NASA Technical Reports Server (NTRS)

Spiger, R. J.; Anderson, H. R.

1975-01-01

Measurements of electron pitch angle distributions and energy spectra over a broad auroral band were used to calculate net electric current carried by auroral electrons in the vicinity of the band. The particle energy spectrometers were carried by a Nike-Tomahawk rocket launched from Poker Flat, Alaska, at 0722 UT on February 25, 1972. Data are presented which indicate the existence of upward field-aligned currents of electrons in the energy range 0.5-20 keV. The spatial relationship of these currents to visual structure of the auroral arc and the characteristics of the electrons carrying the currents are discussed.

Automation of the CCTV-mediated detection of individuals illegally carrying firearms: combining psychological and technological approaches

NASA Astrophysics Data System (ADS)

Darker, Iain T.; Kuo, Paul; Yang, Ming Yuan; Blechko, Anastassia; Grecos, Christos; Makris, Dimitrios; Nebel, Jean-Christophe; Gale, Alastair G.

2009-05-01

Findings from the current UK national research programme, MEDUSA (Multi Environment Deployable Universal Software Application), are presented. MEDUSA brings together two approaches to facilitate the design of an automatic, CCTV-based firearm detection system: psychological-to elicit strategies used by CCTV operators; and machine vision-to identify key cues derived from camera imagery. Potentially effective human- and machine-based strategies have been identified; these will form elements of the final system. The efficacies of these algorithms have been tested on staged CCTV footage in discriminating between firearms and matched distractor objects. Early results indicate the potential for this combined approach.

Determination of the mutagenic and genotoxic potential of simulated leachate from an automobile workshop soil on eukaryotic system.

PubMed

Alabi, Okunola Adenrele; Omosebi, Omotoyosi; Chizea, Ifychukwwu

2015-07-01

Contamination of soil and water bodies with spent engine oil and petroleum products is a serious ecological problem, primarily in the automobile workshops and garages. This has potential short and chronic adverse health risks. Information is currently scarce on the potential mutagenicity and genotoxicity of such wastes. In this study, the potential mutagenic and genotoxic effects of simulated leachate from automobile workshop soil in Sagamu, Ogun state, Nigeria, were investigated. The assays utilized were bone marrow micronucleus (MN) and chromosome aberration (CA), sperm morphology and sperm count in mice. The physicochemical analysis of the leachate was also carried out. Experiments were carried out at concentrations of 1, 5, 10, 25, 50, 75 and 100% (volume per volume; leachate:distilled water) of the leachate sample. MN analysis showed a concentration-dependent induction of micronucleated polychromatic erythrocytes across the treatment groups. In the CA test, there was concentration-dependent significant reduction in mitotic index and induction of different types of CAs. Assessment of sperm shape showed a significant increase in sperm abnormalities with significant decrease in mean sperm count in treated groups. Heavy metals analyzed in the tested sample are believed to contribute significantly to the observed genetic damage. This indicates that automobile workshop soil-simulated leachate contains potential genotoxic agents and constitutes a genetic risk in exposed human population. © The Author(s) 2013.

Twin lead ballistic conductor based on nanoribbon edge transport

NASA Astrophysics Data System (ADS)

Konôpka, Martin; Dieška, Peter

2018-03-01

If a device like a graphene nanoribbon (GNR) has all its four corners attached to electric current leads, the device becomes a quantum junction through which two electrical circuits can interact. We study such system theoretically for stationary currents. The 4-point energy-dependent conductance matrix of the nanostructure and the classical resistors in the circuits are parameters of the model. The two bias voltages in the circuits are the control variables of the studied system while the electrochemical potentials at the device's terminals are non-trivially dependent on the voltages. For the special case of the linear-response regime analytical formulae for the operation of the coupled quantum-classical device are derived and applied. For higher bias voltages numerical solutions are obtained. The effects of non-equilibrium Fermi levels are captured using a recursive algorithm in which self-consistency between the electrochemical potentials and the currents is reached within few iterations. The developed approach allows to study scenarios ranging from independent circuits to strongly coupled ones. For the chosen model of the GNR with highly conductive zigzag edges we determine the regime in which the single device carries two almost independent currents.

SAMPIE Measurements of the Space Station Plasma Current Analyzed

NASA Technical Reports Server (NTRS)

1996-01-01

In March of 1994, STS-62 carried the NASA Lewis Research Center's Solar Array Module Plasma Interactions Experiment (SAMPIE) into orbit, where it investigated the plasma current collected and the arcs from solar arrays and other space power materials immersed in the low-Earth-orbit space plasma. One of the important experiments conducted was the plasma current collected by a four-cell coupon sample of solar array cells for the international space station. The importance of this experiment dates back to the 1990 and 1991 meetings of the Space Station Electrical Grounding Tiger Team. The Tiger Team determined that unless the electrical potentials on the space station structure were actively controlled via a plasma contactor, the space station structure would arc into the plasma at a rate that would destroy the thermal properties of its surface coatings in only a few years of operation. The space station plasma contactor will control its potentials by emitting electrons into the surrounding low-Earth-orbit plasma at the same rate that they are collected by the solar arrays. Thus, the level at which the space station solar arrays can collect current is very important in verifying that the plasma contactor design can do its job.

Air Force Physician and Dentist Multiyear Special Pay: Current Status and Potential Reforms

DTIC Science & Technology

2009-01-01

A general practice physi- cian in the pre -1993 system would have been a 932X, a neurosurgeon would have been a 941XF. 22 Air Force Physician and...years of residency training. Those in surgical specialties (including obstet- rics and orthopedics) sometimes completed longer residencies and were...11.5 years), but, as noted, surgical specialties carry residencies of seven years or longer, and surgeons may have also taken time from their Air

Usage of information safety requirements in improving tube bending process

NASA Astrophysics Data System (ADS)

Livshitz, I. I.; Kunakov, E.; Lontsikh, P. A.

2018-05-01

This article is devoted to an improvement of the technological process's analysis with the information security requirements implementation. The aim of this research is the competition increase analysis in aircraft industry enterprises due to the information technology implementation by the example of the tube bending technological process. The article analyzes tube bending kinds and current technique. In addition, a potential risks analysis in a tube bending technological process is carried out in terms of information security.

The Adsorption of Bromide Ion at Mercury from Propylene Carbonate Solutions of Constant Ionic Strength

DTIC Science & Technology

1991-05-20

Chemistry University of California Davis, CA 95616 * To whom correspondence should be addressed. t Permanent address: Instituto de Fisica e Quimica ...I]. In the case of Br- ion adsorption at Hg, studies have been carried out in water [2-4] and N- methylformamide solutions [5,6] of both varying and...discussed with respect to current theoretical developments. 4 Experimental Differential capacity against potential data were obtained for the mercury

A new approach to the method of source-sink potentials for molecular conduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pickup, Barry T., E-mail: B.T.Pickup@sheffield.ac.uk, E-mail: P.W.Fowler@sheffield.ac.uk; Fowler, Patrick W., E-mail: B.T.Pickup@sheffield.ac.uk, E-mail: P.W.Fowler@sheffield.ac.uk; Borg, Martha

2015-11-21

We re-derive the tight-binding source-sink potential (SSP) equations for ballistic conduction through conjugated molecular structures in a form that avoids singularities. This enables derivation of new results for families of molecular devices in terms of eigenvectors and eigenvalues of the adjacency matrix of the molecular graph. In particular, we define the transmission of electrons through individual molecular orbitals (MO) and through MO shells. We make explicit the behaviour of the total current and individual MO and shell currents at molecular eigenvalues. A rich variety of behaviour is found. A SSP device has specific insulation or conduction at an eigenvalue ofmore » the molecular graph (a root of the characteristic polynomial) according to the multiplicities of that value in the spectra of four defined device polynomials. Conduction near eigenvalues is dominated by the transmission curves of nearby shells. A shell may be inert or active. An inert shell does not conduct at any energy, not even at its own eigenvalue. Conduction may occur at the eigenvalue of an inert shell, but is then carried entirely by other shells. If a shell is active, it carries all conduction at its own eigenvalue. For bipartite molecular graphs (alternant molecules), orbital conduction properties are governed by a pairing theorem. Inertness of shells for families such as chains and rings is predicted by selection rules based on node counting and degeneracy.« less

Glycolysis-related proteins are broad spectrum vaccine candidates against aquacultural pathogens.

PubMed

Liu, Xiaohong; Sun, Jiamin; Wu, Haizhen

2017-07-05

Reverse vaccinology (RV) has become a popular method for developing vaccines. Although Edwardsiella tarda is deemed to be an important fish pathogen, so far, no reports have used a genome-based approach to screen vaccine candidates against E. tarda. In the current study, protective antigens of E. tarda were screened using RV. Large-scale cloning, expression and purification of potential candidates were carried out, and their immunoprotective potential was evaluated. A candidate fructose-bisphosphate aldolase (FBA) exhibited broad spectrum protection, as did another glycolysis-related protein glyceraldehyde-3-phosphate dehydrogenase (GAPDH), which we reported previously, indicating the potential of other glycolysis-related proteins of E. tarda as broad spectrum protective antigens. In total, half (5 out 10) of these proteins showed prominent immunoprotective potential. Therefore, we suggest that glycolysis-related proteins are a class of potential broad spectrum protective antigens and that these proteins should be preferentially selected. Copyright © 2017 Elsevier Ltd. All rights reserved.

Current EU-27 technical potential of organic waste streams for biogas and energy production.

PubMed

Lorenz, Helge; Fischer, Peter; Schumacher, Britt; Adler, Philipp

2013-11-01

Anaerobic digestion of organic waste generated by households, businesses, agriculture, and industry is an important approach as method of waste treatment - especially with regard to its potential as an alternative energy source and its cost-effectiveness. Separate collection of biowaste from households or vegetal waste from public green spaces is already established in some EU-27 countries. The material recovery in composting plants is common for biowaste and vegetal waste. Brewery waste fractions generated by beer production are often used for animal feeding after a suitable preparation. Waste streams from paper industry generated by pulp and paper production such as black liquor or paper sludge are often highly contaminated with toxic substances. Recovery of chemicals and the use in thermal processes like incineration, pyrolysis, and gasification are typical utilization paths. The current utilization of organic waste from households and institutions (without agricultural waste) was investigated for EU-27 countries with Germany as an in-depth example. Besides of biowaste little is known about the suitability of waste streams from brewery and paper industry for anaerobic digestion. Therefore, an evaluation of the most important biogas process parameters for different substrates was carried out, in order to calculate the biogas utilization potential of these waste quantities. Furthermore, a calculation of biogas energy potentials was carried out for defined waste fractions which are most suitable for anaerobic digestion. Up to 1% of the primary energy demand can be covered by the calculated total biogas energy potential. By using a "best-practice-scenario" for separately collected biowaste, the coverage of primary energy demand may be increased above 2% for several countries. By using sector-specific waste streams, for example the German paper industry could cover up to 4.7% and the German brewery industry up to 71.2% of its total energy demand. Copyright © 2013 Elsevier Ltd. All rights reserved.

A Study of the Economic Benefit Potential of Intermodal Transports

NASA Technical Reports Server (NTRS)

Nelson, J. M.; Kawai, R. T.; Gregg, R. D.; McKinley, Robert E., Jr. (Technical Monitor)

2001-01-01

A conceptual study was conducted to determine the benefit potential of an Intermodal Transport in which quick change payload modules are used to reduce the cost of air travel by increasing daily utilization. Three basic concepts varying the degree of modularity were investigated for a 122,000 pounds payload 3,000 NM range regional wide body transport. The profit potential for operating as a passenger transport during the day and as a freighter at night was assessed. Assuming current levels of profitability, Intermodal operations could offer an operating cost reduction potential up to 20%. Enabling technology needs are identified as very quiet aircraft for expanded night operations, distributed load carrying quick disconnect latching, and configuration dependent safety issues. Recommendations are made to explore if additional benefits are possible from alternative mission and usage modules.

Method and apparatus to trigger superconductors in current limiting devices

DOEpatents

Yuan, Xing; Hazelton, Drew Willard; Walker, Michael Stephen

2004-10-26

A method and apparatus for magnetically triggering a superconductor in a superconducting fault current limiter to transition from a superconducting state to a resistive state. The triggering is achieved by employing current-carrying trigger coil or foil on either or both the inner diameter and outer diameter of a superconductor. The current-carrying coil or foil generates a magnetic field with sufficient strength and the superconductor is disposed within essentially uniform magnetic field region. For superconductor in a tubular-configured form, an additional magnetic field can be generated by placing current-carrying wire or foil inside the tube and along the center axial line.

Electrogenic glutamate uptake is a major current carrier in the membrane of axolotl retinal glial cells

NASA Astrophysics Data System (ADS)

Brew, Helen; Attwell, David

1987-06-01

Glutamate is taken up avidly by glial cells in the central nervous system1. Glutamate uptake may terminate the transmitter action of glutamate released from neurons1, and keep extracellular glutamate at concentrations below those which are neurotoxic. We report here that glutamate evokes a large inward current in retinal glial cells which have their membrane potential and intracellular ion concentrations controlled by the whole-cell patch-clamp technique2. This current seems to be due to an electrogenic glutamate uptake carrier, which transports at least two sodium ions with every glutamate anion carried into the cell. Glutamate uptake is strongly voltage-dependent, decreasing at depolarized potentials: when fully activated, it contributes almost half of the conductance in the part of the glial cell membrane facing the retinal neurons. The spatial localization, glutamate affinity and magnitude of the uptake are appropriate for terminating the synaptic action of glutamate released from photoreceptors and bipolar cells. These data challenge present explanations of how the b-wave of the electroretinogram is generated, and suggest a mechanism for non-vesicular voltage-dependent release of glutamate from neurons.

Return currents in solar flares - Collisionless effects

NASA Technical Reports Server (NTRS)

Rowland, H. L.; Vlahos, L.

1985-01-01

If the primary, precipitating electrons in a solar flare are unstable to beam plasma interactions, it is shown that strong Langmuir turbulence can seriously modify the way in which a return current is carried by the background plasma. In particular, the return (or reverse) current will not be carried by the bulk of the electrons, but by a small number of high velocity electrons. For beam/plasma densities greater than 0.01, this can reduce the effects of collisions on the return current. For higher density beams where the return current could be unstable to current driven instabilities, the effects of strong turbulence anomalous resistivity is shown to prevent the appearance of such instabilities. Again in this regime, how the return current is carried is determined by the beam generated strong turbulence.

Nonlinear reconnecting edge localized modes in current-carrying plasmas

DOE PAGES

Ebrahimi, F.

2017-05-22

Nonlinear edge localized modes in a tokamak are examined using global three-dimensional resistive magnetohydrodynamics simulations. Coherent current-carrying filament (ribbon-like) structures wrapped around the torus are nonlinearly formed due to nonaxisymmetric reconnecting current sheet instabilities, the so-called peeling-like edge localized modes. These fast growing modes saturate by breaking axisymmetric current layers isolated near the plasma edge and go through repetitive relaxation cycles by expelling current radially outward and relaxing it back. The local bidirectional fluctuation-induced electromotive force (emf) from the edge localized modes, the dynamo action, relaxes the axisymmetric current density and forms current holes near the edge. Furthermore, the three-dimensionalmore » coherent current-carrying filament structures (sometimes referred to as 3-D plasmoids) observed here should also have strong implications for solar and astrophysical reconnection.« less

Assessing Potential Habitat and Carrying Capacity for Reintroduction of Plains Bison (Bison bison bison) in Banff National Park

PubMed Central

Steenweg, Robin; Hebblewhite, Mark; Gummer, David; Low, Brian; Hunt, Bill

2016-01-01

Interest in bison (Bison bison, B. bonasus) conservation and restoration continues to grow globally. In Canada, plains bison (B. b. bison) are threatened, occupying less than 0.5% of their former range. The largest threat to their recovery is the lack of habitat in which they are considered compatible with current land uses. Fences and direct management make range expansion by most bison impossible. Reintroduction of bison into previously occupied areas that remain suitable, therefore, is critical for bison recovery in North America. Banff National Park is recognized as historical range of plains bison and has been identified as a potential site for reintroduction of a wild population. To evaluate habitat quality and assess if there is sufficient habitat for a breeding population, we developed a Habitat Suitability Index (HSI) model for the proposed reintroduction and surrounding areas in Banff National Park (Banff). We then synthesize previous studies on habitat relationships, forage availability, bison energetics and snowfall scenarios to estimate nutritional carrying capacity. Considering constraints on nutritional carrying capacity, the most realistic scenario that we evaluated resulted in an estimated maximum bison density of 0.48 bison/km2. This corresponds to sufficient habitat to support at least 600 to 1000 plains bison, which could be one of the largest 10 plains bison populations in North America. Within Banff, there is spatial variation in predicted bison habitat suitability and population size that suggests one potential reintroduction site as the most likely to be successful from a habitat perspective. The successful reintroduction of bison into Banff would represent a significant global step towards conserving this iconic species, and our approach provides a useful template for evaluating potential habitat for other endangered species reintroductions into their former range. PMID:26910226

Theoretical Evaluation of Foam Proppant Carriers

NASA Astrophysics Data System (ADS)

von Holt, H.; Kam, S.; Williams, W. C.

2017-12-01

Hydraulic fracturing in oil wells results in a large amount of produced water which must be properly disposed of and is currently a key environmental issue preventing further development in US domestic oil and gas production. The primary function of this liquid is to carry particulates, a.k.a. Proppant, into the stress fractures in order to hold open a pathway in which petroleum can flow into the wellbore. A potential superior technique is to use foam instead of liquid; liquids rely on turbulence to suspend proppant while foams carry particulates on the surfaces. Therefore, foams can carry more proppant deeper into the fractures while typically using 50%-90% less liquid, depending on foam quality. This comparative analysis uses the vorticity equation for a liquid to approximate the base case of particle suspension. This is then compared to a multitude of foam transport models in order to demonstrate the efficacy of foams when used in hydraulic fracturing. This work serves as the basis for future laboratory and hopefully field scale studies of foam proppant carriers.

[Complications after laser hair removal: the standpoint of a dermatological legal expert regarding liability].

PubMed

Bayle, P; Saval, F; Rougé, D; Telmon, N

2015-03-01

Laser hair removal is widely used, including outside medical settings. Potential complications, notably burns, may engage the operator's liability. In this case, investigations by medical experts are frequently requested. We describe 6 expert examinations carried out by the same legal dermatology expert between 2012 and 2014. They concerned burns of varying severity caused by laser hair removal procedures carried out by a doctor, a physiotherapist and 4 beauticians. Laser hair removal is carried out in many beauty centres, although in France it is restricted by law to medical use. This practice is thus currently the subject of legal and economic controversy. The analysis of 6 medical expert investigations of accidents involving laser hair removal illustrates the various types of fault in which the operator's liability may be engaged and it also serves to redefine the legal framework of this act within the realm of aesthetic medicine. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Electrophysiological responses of dissociated type I cells of the rabbit carotid body to cyanide.

PubMed Central

Biscoe, T J; Duchen, M R

1989-01-01

1. The carotid body is the major peripheral sensor of arterial PO2 in the mammal and is excited by cyanide (CN-). Type I cells, the presumed sites for transduction, were freshly dissociated from the carotid body of the adult rabbit and studied with the whole-cell patch clamp technique. 2. Type I cells were hyperpolarized by CN-, the action potential was shortened, and there was an increased after-hyperpolarization. 3. Under voltage clamp control, CN- increased a voltage-dependent outward current, which showed pronounced outward rectification. Tail currents increased by CN- reversed close to the predicted EK, the reversal potential of the CN--induced current depended on extracellular [K+], and the current was blocked by intracellular TEA+ and Cs+. 4. The i-V relation of the CN--induced conductance strongly mirrored that of voltage-gated Ca2+ entry, and the response was abolished by removal of extracellular Ca2+. We conclude that the increased gK is Ca2+ -dependent (gK(Ca]. 5. The Ca2+ current was attenuated by CN-, and showed an increased rate of inactivation. Thus, the increased gK(Ca) must result from an alteration in Ca2+ homeostasis independent of the Ca2+ current, and not an increased Ca2+ entry through voltage-activated channels. 6. Carbachol also hyperpolarized cells and increased a K+ conductance. 7. At depolarized holding potentials a steady-state outward current was increased by CN-. The current reversed close to EK, and was associated with increased current fluctuations. Noise analysis showed that a channel conductance of 3 pS carries the current. 8. The response to CN- was not impaired by the inclusion of 5 mM-MgATP in the patch pipette. 9. If signals to the CNS are initiated by the calcium-dependent release of transmitters from type I cells, transduction would appear to be the direct consequence of the energy dependence of Ca2+ homeostasis. PMID:2557439

Cumulative irritation potential among metronidazole gel 1%, metronidazole gel 0.75%, and azelaic acid gel 15%.

PubMed

Colón, Luz E; Johnson, Lori A; Gottschalk, Ronald W

2007-04-01

Topical therapy for rosacea aims to reduce inflammatory lesions and decrease erythema but can carry side effects such as stinging, pruritus, and burning. Metronidazole and azelaic acid gel 15% are U.S. Food and Drug Administration-approved for the treatment of rosacea. The current study was conducted to assess the cumulative irritation potential of 2 formulations of metronidazole 0.75% gel and 1% gel--and azelaic acid gel 15% over 21 days (N=36). Results of this study demonstrated a significantly greater poten tial for irritation from azelaic acid compared with metronidazole gel 0.75% (P < .0001), which had significantly greater potential for irritation compared with metronidazole gel 1% (P = .0054). Metronidazole gel 1% had a similar profile to white petrolatum.

Local Dynamic Stability Associated with Load Carrying

PubMed Central

Lockhart, Thurmon E

2013-01-01

Objectives Load carrying tasks are recognized as one of the primary occupational factors leading to slip and fall injuries. Nevertheless, the mechanisms associated with load carrying and walking stability remain illusive. The objective of the current study was to apply local dynamic stability measure in walking while carrying a load, and to investigate the possible adaptive gait stability changes. Methods Current study involved 25 young adults in a biomechanics research laboratory. One tri-axial accelerometer was used to measure three-dimensional low back acceleration during continuous treadmill walking. Local dynamic stability was quantified by the maximum Lyapunov exponent (maxLE) from a nonlinear dynamics approach. Results Long term maxLE was found to be significant higher under load condition than no-load condition in all three reference axes, indicating the declined local dynamic stability associated with load carrying. Conclusion Current study confirmed the sensitivity of local dynamic stability measure in load carrying situation. It was concluded that load carrying tasks were associated with declined local dynamic stability, which may result in increased risk of fall accident. This finding has implications in preventing fall accidents associated with occupational load carrying. PMID:23515183

Landmine policy in the near-term: a framework for technology analysis and action

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eimerl, D., LLNL

1997-08-01

Any effective solution to the problem of leftover landmines and other post-conflict unexploded ordnance (UXO) must take into account the real capabilities of demining technologies and the availability of sufficient resources to carry out demining operations. Economic and operational factors must be included in analyses of humanitarian demining. These factors will provide a framework for using currently available resources and technologies to complete this task in a time frame that is both practical and useful. Since it is likely that reliable advanced technologies for demining are still several years away, this construct applies to the intervening period. It may alsomore » provide a framework for utilizing advanced technologies as they become available. This study is an economic system model for demining operations carried out by the developed nations that clarifies the role and impact of technology on the economic performance and viability of these operations. It also provides a quantitative guide to assess the performance penalties arising from gaps in current technology, as well as the potential advantages and desirable features of new technologies that will significantly affect the international community`s ability to address this problem. Implications for current and near-term landmine and landmine technology policies are drawn.« less

Theory of runaway electrons in ITER: Equations, important parameters, and implications for mitigation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boozer, Allen H., E-mail: ahb17@columbia.edu

2015-03-15

The plasma current in ITER cannot be allowed to transfer from thermal to relativistic electron carriers. The potential for damage is too great. Before the final design is chosen for the mitigation system to prevent such a transfer, it is important that the parameters that control the physics be understood. Equations that determine these parameters and their characteristic values are derived. The mitigation benefits of the injection of impurities with the highest possible atomic number Z and the slowing plasma cooling during halo current mitigation to ≳40 ms in ITER are discussed. The highest possible Z increases the poloidal flux consumptionmore » required for each e-fold in the number of relativistic electrons and reduces the number of high energy seed electrons from which exponentiation builds. Slow cooling of the plasma during halo current mitigation also reduces the electron seed. Existing experiments could test physics elements required for mitigation but cannot carry out an integrated demonstration. ITER itself cannot carry out an integrated demonstration without excessive danger of damage unless the probability of successful mitigation is extremely high. The probability of success depends on the reliability of the theory. Equations required for a reliable Monte Carlo simulation are derived.« less

Gravitational biology on the space station

NASA Technical Reports Server (NTRS)

Keefe, J. R.; Krikorian, A. D.

1983-01-01

The current status of gravitational biology is summarized, future areas of required basic research in earth-based and spaceflight projects are presented, and potential applications of gravitational biology on a space station are demonstrated. Topics covered include vertebrate reproduction, prenatal/postnatal development, a review of plant space experiments, the facilities needed for growing plants, gravimorphogenesis, thigmomorphogenesis, centrifuges, maintaining a vivarium, tissue culture, and artificial human organ generation. It is proposed that space stations carrying out these types of long-term research be called the National Space Research Facility.

Deep space network resource scheduling approach and application

NASA Technical Reports Server (NTRS)

Eggemeyer, William C.; Bowling, Alan

1987-01-01

Deep Space Network (DSN) resource scheduling is the process of distributing ground-based facilities to track multiple spacecraft. The Jet Propulsion Laboratory has carried out extensive research to find ways of automating this process in an effort to reduce time and manpower costs. This paper presents a resource-scheduling system entitled PLAN-IT with a description of its design philosophy. The PLAN-IT's current on-line usage and limitations in scheduling the resources of the DSN are discussed, along with potential enhancements for DSN application.

Apollo experience report: Detection and minimization of ignition hazards from water/glycol contamination of silver-clad electrical circuitry

NASA Technical Reports Server (NTRS)

Downs, W. R.

1976-01-01

The potential flammability hazard when a water/glycol solution contacts defectively insulated silver-clad copper circuitry or electrical components carrying a direct current is described. The chemical reactions and means for detecting them are explained. Methods for detecting and cleaning contaminated areas and the use of inhibitors to arrest chemical reactivity are also explained. Preventive measures to minimize hazards are given. Photomicrographs of the chemical reactions occurring on silver clad wires are also included.

Investigating the Potential Range Expansion of the Vector Mosquito Aedes Aegypti in Mexico with NASA Earth Science Remote Sensing Results

NASA Technical Reports Server (NTRS)

Estes, Sue M.

2011-01-01

Dengue (Breakbone) fever is caused by one of four viruses carried by mosquitoes in tropical and subtropical areas. Cases have increased dramatically in the past few decades; there are currently approximately 100 million infections annually around the globe. Our project will integrate environmental observations, including weather, land use, vegetation type, amount and greenness, soil moisture, and mosquito populations with investigations of the human dynamics of the system via household surveys.

The reduction, verification and interpretation of MAGSAT magnetic data over Canada

NASA Technical Reports Server (NTRS)

Coles, R. L. (Principal Investigator); Haines, G. V.; Vanbeek, G. J.; Walker, J. K.; Newitt, L. R.

1982-01-01

Consideration is being given to representing the magnetic field in the area 40 deg N to 83 deg N by means of functions in spherical coordinates. A solution to Laplace's equation for the magnetic potential over a restricted area was found, and programming and testing are currently being carried out. Magnetic anomaly modelling is proceeding. The program SPHERE, which was adapted to function correctly on the Cyber computer, is now operational, for deriving gravity and magnetic models in a spherical coordinate system.

Hotspot relaxation dynamics in a current-carrying superconductor

NASA Astrophysics Data System (ADS)

Marsili, F.; Stevens, M. J.; Kozorezov, A.; Verma, V. B.; Lambert, Colin; Stern, J. A.; Horansky, R. D.; Dyer, S.; Duff, S.; Pappas, D. P.; Lita, A. E.; Shaw, M. D.; Mirin, R. P.; Nam, S. W.

2016-03-01

We experimentally studied the dynamics of optically excited hotspots in current-carrying WSi superconducting nanowires as a function of bias current, bath temperature, and excitation wavelength. We observed that the hotspot relaxation time depends on bias current, temperature, and wavelength. We explained this effect with a model based on quasiparticle recombination, which provides insight into the quasiparticle dynamics of superconductors.

Currents between tethered electrodes in a magnetized laboratory plasma

NASA Technical Reports Server (NTRS)

Stenzel, R. L.; Urrutia, J. M.

1989-01-01

Laboratory experiments on important plasma physics issues of electrodynamic tethers were performed. These included current propagation, formation of wave wings, limits of current collection, nonlinear effects and instabilities, charging phenomena, and characteristics of transmission lines in plasmas. The experiments were conducted in a large afterglow plasma. The current system was established with a small electron-emitting hot cathode tethered to an electron-collecting anode, both movable across the magnetic field and energized by potential difference up to V approx.=100 T(sub e). The total current density in space and time was obtained from complete measurements of the perturbed magnetic field. The fast spacecraft motion was reproduced in the laboratory by moving the tethered electrodes in small increments, applying delayed current pulses, and reconstructing the net field by a linear superposition of locally emitted wavelets. With this technique, the small-amplitude dc current pattern is shown to form whistler wings at each electrode instead of the generally accepted Alfven wings. For the beam electrode, the whistler wing separates from the field-aligned beam which carries no net current. Large amplitude return currents to a stationary anode generate current-driven microinstabilities, parallel electric fields, ion depletions, current disruptions and time-varying electrode charging. At appropriately high potentials and neutral densities, excess neutrals are ionized near the anode. The anode sheath emits high-frequency electron transit-time oscillations at the sheath-plasma resonance. The beam generates Langmuir turbulence, ion sound turbulence, electron heating, space charge fields, and Hall currents. An insulated, perfectly conducting transmission line embedded in the plasma becomes lossy due to excitation of whistler waves and magnetic field diffusion effects. The implications of the laboratory observations on electrodynamic tethers in space are discussed.

Analysis of high field effects on the steady-state current-voltage response of semi-insulating 4H-SiC for photoconductive switch applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tiskumara, R.; Joshi, R. P., E-mail: ravi.joshi@ttu.edu; Mauch, D.

A model-based analysis of the steady-state, current-voltage response of semi-insulating 4H-SiC is carried out to probe the internal mechanisms, focusing on electric field driven effects. Relevant physical processes, such as multiple defects, repulsive potential barriers to electron trapping, band-to-trap impact ionization, and field-dependent detrapping, are comprehensively included. Results of our model match the available experimental data fairly well over orders of magnitude variation in the current density. A number of important parameters are also extracted in the process through comparisons with available data. Finally, based on our analysis, the possible presence of holes in the samples can be discounted upmore » to applied fields as high as ∼275 kV/cm.« less

Kv2 Channel Regulation of Action Potential Repolarization and Firing Patterns in Superior Cervical Ganglion Neurons and Hippocampal CA1 Pyramidal Neurons

PubMed Central

Liu, Pin W.

2014-01-01

Kv2 family “delayed-rectifier” potassium channels are widely expressed in mammalian neurons. Kv2 channels activate relatively slowly and their contribution to action potential repolarization under physiological conditions has been unclear. We explored the function of Kv2 channels using a Kv2-selective blocker, Guangxitoxin-1E (GxTX-1E). Using acutely isolated neurons, mixed voltage-clamp and current-clamp experiments were done at 37°C to study the physiological kinetics of channel gating and action potentials. In both rat superior cervical ganglion (SCG) neurons and mouse hippocampal CA1 pyramidal neurons, 100 nm GxTX-1E produced near-saturating block of a component of current typically constituting ∼60–80% of the total delayed-rectifier current. GxTX-1E also reduced A-type potassium current (IA), but much more weakly. In SCG neurons, 100 nm GxTX-1E broadened spikes and voltage clamp experiments using action potential waveforms showed that Kv2 channels carry ∼55% of the total outward current during action potential repolarization despite activating relatively late in the spike. In CA1 neurons, 100 nm GxTX-1E broadened spikes evoked from −70 mV, but not −80 mV, likely reflecting a greater role of Kv2 when other potassium channels were partially inactivated at −70 mV. In both CA1 and SCG neurons, inhibition of Kv2 channels produced dramatic depolarization of interspike voltages during repetitive firing. In CA1 neurons and some SCG neurons, this was associated with increased initial firing frequency. In all neurons, inhibition of Kv2 channels depressed maintained firing because neurons entered depolarization block more readily. Therefore, Kv2 channels can either decrease or increase neuronal excitability depending on the time scale of excitation. PMID:24695716

The human Nav1.5 F1486 deletion associated with long QT syndrome leads to impaired sodium channel inactivation and reduced lidocaine sensitivity

PubMed Central

Song, Weihua; Xiao, Yucheng; Chen, Hanying; Ashpole, Nicole M; Piekarz, Andrew D; Ma, Peilin; Hudmon, Andy; Cummins, Theodore R; Shou, Weinian

2012-01-01

The deletion of phenylalanine 1486 (F1486del) in the human cardiac voltage-gated sodium channel (hNav1.5) is associated with fatal long QT (LQT) syndrome. In this study we determined how F1486del impairs the functional properties of hNav1.5 and alters action potential firing in heterologous expression systems (human embryonic kidney (HEK) 293 cells) and their native cardiomyocyte background. Cells expressing hNav1.5-F1486del exhibited a loss-of-function alteration, reflected by an 80% reduction of peak current density, and several gain-of-function alterations, including reduced channel inactivation, enlarged window current, substantial augmentation of persistent late sodium current and an increase in ramp current. We also observed substantial action potential duration (APD) prolongation and prominent early afterdepolarizations (EADs) in neonatal cardiomyocytes expressing the F1486del channels, as well as in computer simulations of myocyte activity. In addition, lidocaine sensitivity was dramatically reduced, which probably contributed to the poor therapeutic outcome observed in the patient carrying the hNav1.5-F1486del mutation. Therefore, despite the significant reduction in peak current density, the F1486del mutation also leads to substantial gain-of-function alterations that are sufficient to cause APD prolongation and EADs, the predominant characteristic of LQTs. These data demonstrate that hNav1.5 mutations can have complex functional consequences and highlight the importance of identifying the specific molecular defect when evaluating potential treatments for individuals with prolonged QT intervals. PMID:22826127

46 CFR 28.365 - Overcurrent protection and switched circuits.

Code of Federal Regulations, 2011 CFR

2011-10-01

.... (c) Each ungrounded current carrying conductor must be protected in accordance with its current carrying capacity by a circuit breaker or fuse at the connection to the switchboard or distribution panel...

Sialidase-Inhibiting Antibody Titers Correlate with Protection from Heterologous Influenza Virus Strains of the Same Neuraminidase Subtype.

PubMed

Walz, Lisa; Kays, Sarah-Katharina; Zimmer, Gert; von Messling, Veronika

2018-06-20

Immune responses induced by currently licensed inactivated influenza vaccines are mainly directed against the hemagglutinin (HA) glycoprotein, the immunodominant antigen of influenza viruses. The resulting antigenic drift of HA requires frequent updating of the vaccine composition and annual revaccination. On the other hand, the level of antibodies directed against the neuraminidase (NA) glycoprotein, the second major influenza virus antigen, vary greatly. To investigate the potential of the more conserved NA protein for the induction of a subtype-specific protection, vesicular stomatitis virus-based replicons expressing a panel of N1 proteins from prototypic seasonal and pandemic H1N1 strain and human H5N1 and H7N9 isolates were generated. Immunization of mice and ferrets with the replicon carrying the matched N1 protein resulted in robust humoral and cellular immune responses and protected against challenge with the homologous influenza virus with similar efficacy as the matched HA protein, illustrating the potential of the NA protein as vaccine antigen. The extent of protection after immunization with mismatched N1 proteins correlated with the level of cross-reactive sialidase-inhibiting antibody titers. Passive serum transfer experiments in mice confirmed that these functional antibodies determine subtype-specific cross-protection. Our findings illustrate the potential of NA-specific immunity for achieving broader protection against antigenic drift variants or newly emerging viruses carrying the same NA but a different HA subtype. IMPORTANCE Despite the availability of vaccines, annual influenza virus epidemics cause 250,000 to 500,000 deaths worldwide. Currently licensed inactivated vaccines, which are standardized for the amount of the hemagglutinin (HA) antigen, primarily induce strain-specific antibodies whereas the immune response to the neuraminidase (NA) antigen, which is also present on the viral surface, is usually low. Using NA-expressing single-cycle vesicular stomatitis virus replicons, we show that the NA antigen not only conferred protection of mice and ferrets to the matched influenza strains, but also against viruses carrying NA proteins from other strains of the same subtype. The extent of protection correlated with the level of cross-reactive NA-inhibiting antibodies. This highlights the potential of the NA antigen for the development of more broadly protective influenza vaccines. Such vaccines may also provide partial protection against newly emerging strains with the same NA but a different HA subtype. Copyright © 2018 American Society for Microbiology.

Disinfection potential of electrolyzed solutions containing sodium chloride at low concentrations.

PubMed

Morita, C; Sano, K; Morimatsu, S; Kiura, H; Goto, T; Kohno, T; Hong, W U; Miyoshi, H; Iwasawa, A; Nakamura, Y; Tagawa, M; Yokosuka, O; Saisho, H; Maeda, T; Katsuoka, Y

2000-03-01

Electrolyzed products of sodium chloride solution were examined for their disinfection potential against hepatitis B virus (HBV) and human immunodeficiency virus (HIV) in vitro. Electrolysis of 0.05% NaCl in tap water was carried out for 45 min at room temperature using a 3 A electric current in separate wells installed with positive and negative electrodes. The electrolyzed products were obtained from the positive well. The oxidation reduction potential (ORP), pH and free chlorine content of the product were 1053 mV, pH 2.34 and 4.20 ppm, respectively. The products modified the antigenicity of the surface protein of HBV as well as the infectivity of HIV in time- and concentration-dependent manner. Although the inactivating potential was decreased by the addition of contaminating protein, recycling of the product or continuous addition of fresh product may restore the complete disinfection against bloodborne pathogens.

Influence of the Ambient Electric Field on Measurements of the Actively Controlled Spacecraft Potential by MMS

NASA Astrophysics Data System (ADS)

Torkar, K.; Nakamura, R.; Andriopoulou, M.; Giles, B. L.; Jeszenszky, H.; Khotyaintsev, Y. V.; Lindqvist, P.-A.; Torbert, R. B.

2017-12-01

Space missions with sophisticated plasma instrumentation such as Magnetospheric Multiscale, which employs four satellites to explore near-Earth space benefit from a low electric potential of the spacecraft, to improve the plasma measurements and therefore carry instruments to actively control the potential by means of ion beams. Without control, the potential varies in anticorrelation with plasma density and temperature to maintain an equilibrium between the plasma current and the one of photoelectrons produced at the surface and overcoming the potential barrier. A drawback of the controlled, almost constant potential is the difficulty to use it as convenient estimator for plasma density. This paper identifies a correlation between the spacecraft potential and the ambient electric field, both measured by double probes mounted at the end of wire booms, as the main responsible for artifacts in the potential data besides the known effect of the variable photoelectron production due to changing illumination of the surface. It is shown that the effect of density variations is too weak to explain the observed correlation with the electric field and that a correction of the artifacts can be achieved to enable the reconstruction of the uncontrolled potential and plasma density in turn. Two possible mechanisms are discussed: the asymmetry of the current-voltage characteristic determining the probe to plasma potential and the fact that a large equipotential structure embedded in an electric field results in asymmetries of both the emission and spatial distribution of photoelectrons, which results in an increase of the spacecraft potential.

Optimization of a Hot Structure Aeroshell and Nose Cap for Mars Atmospheric Entry

NASA Technical Reports Server (NTRS)

Langston, Sarah L.; Lang, Christapher G.; Samareh, Jamshid A.; Daryabeigi, Kamran

2016-01-01

The National Aeronautics and Space Administration (NASA) is preparing to send humans beyond Low Earth Orbit and eventually to the surface of Mars. As part of the Evolvable Mars Campaign, different vehicle configurations are being designed and considered for delivering large payloads to the surface of Mars. Weight and packing volume are driving factors in the vehicle design, and the thermal protection system (TPS) for planetary entry is a technology area which can offer potential weight and volume savings. The feasibility and potential benefits of a ceramic matrix composite hot structure concept for different vehicle configurations are explored in this paper, including the nose cap for a Hypersonic Inflatable Aerodynamic Decelerator (HIAD) and an aeroshell for a mid lift-to-drag (Mid L/D) concept. The TPS of a planetary entry vehicle is a critical component required to survive the severe aerodynamic heating environment during atmospheric en- try. The current state-of-the-art is an ablative material to protect the vehicle from the heat load. The ablator is bonded to an underlying structure, which carries the mechanical loads associated with entry. The alternative hot structure design utilizes an advanced carbon-carbon material system on the outer surface of the vehicle, which is exposed to the severe heating and acts as a load carrying structure. The preliminary design using the hot structure concept and the ablative concept is determined for the spherical nose cap of the HIAD entry vehicle and the aeroshell of the Mid L/D entry vehicle. The results of the study indicate that the use of hot structures for both vehicle concepts leads to a feasible design with potential weight and volume savings benefits over current state-of-the-art TPS technology that could enable future missions.

Noradrenaline Modulates the Membrane Potential and Holding Current of Medial Prefrontal Cortex Pyramidal Neurons via β1-Adrenergic Receptors and HCN Channels.

PubMed

Grzelka, Katarzyna; Kurowski, Przemysław; Gawlak, Maciej; Szulczyk, Paweł

2017-01-01

The medial prefrontal cortex (mPFC) receives dense noradrenergic projections from the locus coeruleus. Adrenergic innervation of mPFC pyramidal neurons plays an essential role in both physiology (control of memory formation, attention, working memory, and cognitive behavior) and pathophysiology (attention deficit hyperactivity disorder, posttraumatic stress disorder, cognitive deterioration after traumatic brain injury, behavioral changes related to addiction, Alzheimer's disease and depression). The aim of this study was to elucidate the mechanism responsible for adrenergic receptor-mediated control of the resting membrane potential in layer V mPFC pyramidal neurons. The membrane potential or holding current of synaptically isolated layer V mPFC pyramidal neurons was recorded in perforated-patch and classical whole-cell configurations in slices from young rats. Application of noradrenaline (NA), a neurotransmitter with affinity for all types of adrenergic receptors, evoked depolarization or inward current in the tested neurons irrespective of whether the recordings were performed in the perforated-patch or classical whole-cell configuration. The effect of noradrenaline depended on β 1 - and not α 1 - or α 2 -adrenergic receptor stimulation. Activation of β 1 -adrenergic receptors led to an increase in inward Na + current through hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which carry a mixed Na + /K + current. The protein kinase A- and C-, glycogen synthase kinase-3β- and tyrosine kinase-linked signaling pathways were not involved in the signal transduction between β 1 -adrenergic receptors and HCN channels. The transduction system operated in a membrane-delimited fashion and involved the βγ subunit of G-protein. Thus, noradrenaline controls the resting membrane potential and holding current in mPFC pyramidal neurons through β 1 -adrenergic receptors, which in turn activate HCN channels via a signaling pathway involving the βγ subunit.

Noradrenaline Modulates the Membrane Potential and Holding Current of Medial Prefrontal Cortex Pyramidal Neurons via β1-Adrenergic Receptors and HCN Channels

PubMed Central

Grzelka, Katarzyna; Kurowski, Przemysław; Gawlak, Maciej; Szulczyk, Paweł

2017-01-01

The medial prefrontal cortex (mPFC) receives dense noradrenergic projections from the locus coeruleus. Adrenergic innervation of mPFC pyramidal neurons plays an essential role in both physiology (control of memory formation, attention, working memory, and cognitive behavior) and pathophysiology (attention deficit hyperactivity disorder, posttraumatic stress disorder, cognitive deterioration after traumatic brain injury, behavioral changes related to addiction, Alzheimer’s disease and depression). The aim of this study was to elucidate the mechanism responsible for adrenergic receptor-mediated control of the resting membrane potential in layer V mPFC pyramidal neurons. The membrane potential or holding current of synaptically isolated layer V mPFC pyramidal neurons was recorded in perforated-patch and classical whole-cell configurations in slices from young rats. Application of noradrenaline (NA), a neurotransmitter with affinity for all types of adrenergic receptors, evoked depolarization or inward current in the tested neurons irrespective of whether the recordings were performed in the perforated-patch or classical whole-cell configuration. The effect of noradrenaline depended on β1- and not α1- or α2-adrenergic receptor stimulation. Activation of β1-adrenergic receptors led to an increase in inward Na+ current through hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which carry a mixed Na+/K+ current. The protein kinase A- and C-, glycogen synthase kinase-3β- and tyrosine kinase-linked signaling pathways were not involved in the signal transduction between β1-adrenergic receptors and HCN channels. The transduction system operated in a membrane-delimited fashion and involved the βγ subunit of G-protein. Thus, noradrenaline controls the resting membrane potential and holding current in mPFC pyramidal neurons through β1-adrenergic receptors, which in turn activate HCN channels via a signaling pathway involving the βγ subunit. PMID:29209170

The Prevalence of Violent Behavior among Lebanese University Students: Association with Behavioral and Mental Health Factors.

PubMed

Itani, Taha; Fischer, Florian; Chu, Janet J; Kraemer, Alexander

2017-11-01

We estimated the prevalence of 2 key violent behaviors (weapons carrying and physical fighting), determined the health risk correlates of violent behavior, such as current tobacco smoking, alcohol binge drinking, and having multiple sexual partners, and investigated the potential mental health factors related to violent behavior among Lebanese university students. Using a cross-sectional design, data were collected from 450 Lebanese university students based on proportionate cluster sampling. Various health and behavioral risk factors were considered for the analyses. The overall prevalence of weapon carrying and physical fighting was reported at 12.7% and 19.1%, respectively. Males reported more violent behavior than females; weapon carrying (20.7% vs 5.2%, p < .001), and physical fighting (31.8% vs 7.3%, p < .001). Students who engaged in violent behaviors were more likely to have risky health behaviors than those who were not involved in violent behaviors. Religiosity had a significant protective effect against engaging in physical fighting after adjusting for socio-demographic factors. This study bridges the gap in the literature about violent behavior among emerging adults in Lebanon. There is a need to monitor weapon carrying by university students especially in a volatile setting like Lebanon.

Psychosocial Distress and Knowledge Deficiencies in Parents of Children in Ireland Who Carry an Altered Cystic Fibrosis Gene.

PubMed

Quigley, S J; Linnane, B; Connellan, S; Ward, A; Ryan, P

2018-06-01

Significant gaps have been identified in parental understanding of CF newborn screening and the consequences of carrying an altered CF gene. Seven potential causes of psychosocial adversity arising from false positive newborn screening for CF have been identified. The current study aimed to increase parents understanding of CF, reduce their levels of stress, and investigate psychosocial adversity arising from false-positive screening. This national study was run over one year in the Republic of Ireland. Parents were recruited for the study following a diagnostic sweat test confirming their child carried a single altered CF gene. Parents were randomly assigned into a control and intervention group, with those in the intervention group receiving a carefully designed information pack. All parents took part in semi-structured interviews. Parents (n = 16) who received an information pack had significantly higher CF knowledge scores than parents (n = 16) in the control group. 66% of parents in the control group misunderstood the health implications of carrying an altered CF gene, no parents in the intervention group had the same misunderstanding. There was no significant difference in stress scores between the groups. Parents of infants who had more than one sweat test due to insufficient sweat quantity had higher overall stress percentiles (50%), than parents of infants who had one sweat test (30%), indicating greater parental stress. The combination of written and audio-visual information contained in the information pack successfully increased parents comprehension of CF. The study also evaluates the potential for psychosocial adversity following false positive newborn screening for CF.

46 CFR 28.860 - Overcurrent protection and switched circuits.

Code of Federal Regulations, 2010 CFR

2010-10-01

... current carrying conductor must be protected in accordance with its current carrying capacity by a circuit breaker or fuse at the connection to the switchboard or distribution panel bus. (d) Each circuit breaker...

46 CFR 28.860 - Overcurrent protection and switched circuits.

Code of Federal Regulations, 2011 CFR

2011-10-01

... current carrying conductor must be protected in accordance with its current carrying capacity by a circuit breaker or fuse at the connection to the switchboard or distribution panel bus. (d) Each circuit breaker...

Errors due to measuring voltage on current-carrying electrodes in electric current computed tomography.

PubMed

Cheng, K S; Simske, S J; Isaacson, D; Newell, J C; Gisser, D G

1990-01-01

Electric current computed tomography is a process for determining the distribution of electrical conductivity inside a body based upon measurements of voltage or current made at the body's surface. Most such systems use different electrodes for the application of current and the measurement of voltage. This paper shows that when a multiplicity of electrodes are attached to a body's surface, the voltage data are most sensitive to changes in resistivity in the body's interior when voltages are measured from all electrodes, including those carrying current. This assertion is true despite the presence of significant levels of skin impedance at the electrodes. This conclusion is supported both theoretically and by experiment. Data were first taken using all electrodes for current and voltage. Then current was applied only at a pair of electrodes, with voltages measured on all other electrodes. We then constructed the second data set by calculation from the first. Targets could be detected with better signal-to-noise ratio by using the reconstructed data than by using the directly measured voltages on noncurrent-carrying electrodes. Images made from voltage data using only noncurrent-carrying electrodes had higher noise levels and were less able to accurately locate targets. We conclude that in multiple electrode systems for electric current computed tomography, current should be applied and voltage should be measured from all available electrodes.

Diagnosing Breast Cancer with Microwave Technology: remaining challenges and potential solutions with machine learning.

PubMed

Oliveira, Bárbara L; Godinho, Daniela; O'Halloran, Martin; Glavin, Martin; Jones, Edward; Conceição, Raquel C

2018-05-19

Currently, breast cancer often requires invasive biopsies for diagnosis, motivating researchers to design and develop non-invasive and automated diagnosis systems. Recent microwave breast imaging studies have shown how backscattered signals carry relevant information about the shape of a tumour, and tumour shape is often used with current imaging modalities to assess malignancy. This paper presents a comprehensive analysis of microwave breast diagnosis systems which use machine learning to learn characteristics of benign and malignant tumours. The state-of-the-art, the main challenges still to overcome and potential solutions are outlined. Specifically, this work investigates the benefit of signal pre-processing on diagnostic performance, and proposes a new set of extracted features that capture the tumour shape information embedded in a signal. This work also investigates if a relationship exists between the antenna topology in a microwave system and diagnostic performance. Finally, a careful machine learning validation methodology is implemented to guarantee the robustness of the results and the accuracy of performance evaluation.

Targeting Hsp90 in urothelial carcinoma

PubMed Central

Skotnicki, Kamil; Landas, Steve; Bratslavsky, Gennady; Bourboulia, Dimitra

2015-01-01

Urothelial carcinoma, or transitional cell carcinoma, is the most common urologic malignancy that carries significant morbidity, mortality, recurrence risk and associated health care costs. Despite use of current chemotherapies and immunotherapies, long-term remission in patients with muscle-invasive or metastatic disease remains low, and disease recurrence is common. The molecular chaperone Heat Shock Protein-90 (Hsp90) may offer an ideal treatment target, as it is a critical signaling hub in urothelial carcinoma pathogenesis and potentiates chemoradiation. Preclinical testing with Hsp90 inhibitors has demonstrated reduced proliferation, enhanced apoptosis and synergism with chemotherapies and radiation. Despite promising preclinical data, clinical trials utilizing Hsp90 inhibitors for other malignancies had modest efficacy. Therefore, we propose that Hsp90 inhibition would best serve as an adjuvant treatment in advanced muscle-invasive or metastatic bladder cancers to potentiate other therapies. An overview of bladder cancer biology, current treatments, molecular targeted therapies, and the role for Hsp90 inhibitors in the treatment of urothelial carcinoma is the focus of this review. PMID:25909217

Tokamak reactor for treating fertile material or waste nuclear by-products

DOEpatents

Kotschenreuther, Michael T.; Mahajan, Swadesh M.; Valanju, Prashant M.

2012-10-02

Disclosed is a tokamak reactor. The reactor includes a first toroidal chamber, current carrying conductors, at least one divertor plate within the first toroidal chamber and a second chamber adjacent to the first toroidal chamber surrounded by a section that insulates the reactor from neutrons. The current carrying conductors are configured to confine a core plasma within enclosed walls of the first toroidal chamber such that the core plasma has an elongation of 1.5 to 4 and produce within the first toroidal chamber at least one stagnation point at a perpendicular distance from an equatorial plane through the core plasma that is greater than the plasma minor radius. The at least one divertor plate and current carrying conductors are configured relative to one another such that the current carrying conductors expand the open magnetic field lines at the divertor plate.

Anaerobic co-digestion of municipal food waste and sewage sludge: A comparative life cycle assessment in the context of a waste service provision.

PubMed

Edwards, Joel; Othman, Maazuza; Crossin, Enda; Burn, Stewart

2017-01-01

This study used life cycle assessment to evaluate the environmental impact of anaerobic co-digestion (AcoD) and compared it against the current waste management system in two case study areas. Results indicated AcoD to have less environmental impact for all categories modelled excluding human toxicity, despite the need to collect and pre-treat food waste separately. Uncertainty modelling confirmed that AcoD has a 100% likelihood of a smaller global warming potential, and for acidification, eutrophication and fossil fuel depletion AcoD carried a greater than 85% confidence of inducing a lesser impact than the current waste service. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Experimental Analysis of Pseudospark Sourced Electron Beam

NASA Astrophysics Data System (ADS)

Kumar, Niraj; Pal, U. N.; Verma, D. K.; Prajapati, J.; Kumar, M.; Meena, B. L.; Tyagi, M. S.; Srivastava, V.

2011-12-01

The pseudospark (PS) discharge has been shown to be a promising source of high brightness, high intensity electron beam pulses. The PS discharge sourced electron beam has potential applications in plasma filled microwave sources where normal material cathode cannot be used. Analysis of the electron beam profile has been done experimentally for different applied voltages. The investigation has been carried out at different axial and radial location inside the drift space in argon atmosphere. This paper represents experimentally found axial and radial variation of the beam current inside the drift tube of PS discharge based plasma cathode electron (PCE) gun. With the help of current density estimation the focusing and defocusing point of electron beam in axial direction can be analyzed.

A new approach for two-terminal electronic memory devices - Storing information on silicon nanowires

NASA Astrophysics Data System (ADS)

Saranti, Konstantina; Alotaibi, Sultan; Paul, Shashi

2016-06-01

The work described in this paper focuses on the utilisation of silicon nanowires as the information storage element in flash-type memory devices. Silicon nanostructures have attracted attention due to interesting electrical and optical properties, and their potential integration into electronic devices. A detailed investigation of the suitability of silicon nanowires as the charge storage medium in two-terminal non-volatile memory devices are presented in this report. The deposition of the silicon nanostructures was carried out at low temperatures (less than 400 °C) using a previously developed a novel method within our research group. Two-terminal non-volatile (2TNV) memory devices and metal-insulator-semiconductor (MIS) structures containing the silicon nanowires were fabricated and an in-depth study of their characteristics was carried out using current-voltage and capacitance techniques.

Antimicrobial potential of bacteriocins in poultry and swine production.

PubMed

Ben Lagha, Amel; Haas, Bruno; Gottschalk, Marcelo; Grenier, Daniel

2017-04-11

The routine use of antibiotics in agriculture has contributed to an increase in drug-resistant bacterial pathogens in animals that can potentially be transmitted to humans. In 2000, the World Health Organization identified resistance to antibiotics as one of the most significant global threats to public health and recommended that the use of antibiotics as additives in animal feed be phased out or terminated, particularly those used to treat human infections. Research is currently being carried out to identify alternative antimicrobial compounds for use in animal production. A number of studies, mostly in vitro, have provided evidence indicating that bacteriocins, which are antimicrobial peptides of bacterial origin, may be promising alternatives to conventional antibiotics in poultry and swine production. This review provides an update on bacteriocins and their potential for use in the poultry and swine industries.

Magnetic Fields at the Center of Coils

ERIC Educational Resources Information Center

Binder, Philippe; Hui, Kaleonui; Goldman, Jesse

2014-01-01

In this note we synthesize and extend expressions for the magnetic field at the center of very short and very long current-carrying coils. Elementary physics textbooks present the following equation for the magnetic field inside a very long current-carrying coil (solenoid): B[subscript sol] = µ[subscript 0] (N/L) I, (1) where I is the current, N…

Genetic determinants and potential therapeutic targets for pancreatic adenocarcinoma.

PubMed

Reznik, Robert; Hendifar, Andrew E; Tuli, Richard

2014-01-01

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer deaths in both men and women in the United States, carrying a 5-year survival rate of approximately 5%, which is the poorest prognosis of any solid tumor type. Given the dismal prognosis associated with PDAC, a more thorough understanding of risk factors and genetic predisposition has important implications not only for cancer prevention, but also for screening techniques and the development of personalized therapies. While screening of the general population is not recommended or practicable with current diagnostic methods, studies are ongoing to evaluate its usefulness in people with at least 5- to 10-fold increased risk of PDAC. In order to help identify high-risk populations who would be most likely to benefit from early detection screening tests for pancreatic cancer, discovery of additional pancreatic cancer susceptibility genes is crucial. Thus, specific gene-based, gene-product, and marker-based testing for the early detection of pancreatic cancer are currently being developed, with the potential for these to be useful as potential therapeutic targets as well. The goal of this review is to provide an overview of the genetic basis for PDAC with a focus on germline and familial determinants. A discussion of potential therapeutic targets and future directions in screening and treatment is also provided.

Genetic determinants and potential therapeutic targets for pancreatic adenocarcinoma

PubMed Central

Reznik, Robert; Hendifar, Andrew E.; Tuli, Richard

2014-01-01

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer deaths in both men and women in the United States, carrying a 5-year survival rate of approximately 5%, which is the poorest prognosis of any solid tumor type. Given the dismal prognosis associated with PDAC, a more thorough understanding of risk factors and genetic predisposition has important implications not only for cancer prevention, but also for screening techniques and the development of personalized therapies. While screening of the general population is not recommended or practicable with current diagnostic methods, studies are ongoing to evaluate its usefulness in people with at least 5- to 10-fold increased risk of PDAC. In order to help identify high-risk populations who would be most likely to benefit from early detection screening tests for pancreatic cancer, discovery of additional pancreatic cancer susceptibility genes is crucial. Thus, specific gene-based, gene-product, and marker-based testing for the early detection of pancreatic cancer are currently being developed, with the potential for these to be useful as potential therapeutic targets as well. The goal of this review is to provide an overview of the genetic basis for PDAC with a focus on germline and familial determinants. A discussion of potential therapeutic targets and future directions in screening and treatment is also provided. PMID:24624093

MHD Stability in Compact Stellarators

NASA Astrophysics Data System (ADS)

Fu, Guoyong

1999-11-01

A key issue for current carrying compact stellarators(S.P. Hirshman et al., "Physics of compact stellarators", Phys. Plasmas 6, 1858 (1999).) is the stability of ideal MHD modes. We present recent stability results of external kink modes, ballooning mode, and vertical modes in Quasi-axisymmetric Stellarators (QAS)( A. Reiman et al, "Physics issue in the design of a high beta Quasi-Axisymmetric Stellarator" the 17th IAEA Fusion Energy conference, (Yokohama, Japan, October 1998), Paper ICP/06.) as well as Quasi-Omnigeneous Stellarators (QOS)^2. The 3D stability code Terpsichore(W. A. Cooper et al., Phys. Plasmas 3, 275 (1996)) is used in this study. The vertical stability in a current carrying stellarator is studied for the first time. The vertical mode is found to be stabilized by externally generated poloidal flux(G.Y. Fu et al., "Stability of vertical mode in a current carrying stellarator"., to be submitted). Physically, this is because the external poloidal flux enhances the field line bending energy relative to the current drive term in the MHD energy principle, δ W. A simple stability criteria is derived in the limit of large aspect ratio and constant current density. For wall at infinite distance from the plasma, the amount of external flux needed for stabilization is given by f=(κ^2-κ)/(κ^2+1) where κ is the axisymmetric elongation and f is the fraction of the external rotational transform at the plasma edge. A systematic parameter study shows that the external kink in QAS can be stabilized at high beta ( ~ 5%) without a conducting wall by combination of edge magnetic shear and 3D shaping(G. Y. Fu et al., "MHD stability calculations of high-beta Quasi-Axisymmetric Stellarators", the 17th IAEA Fusion Energy conference, (Yokohama, Japan, October 1998), paper THP1/07.). The optimal shaping is obtained by using an optimizer with kink stability included in its objective function. The physics mechanism for the kink modes is studied by examining relative contributions of individual terms in δ W. It is found the external kinks are mainly driven by the parallel current. The pressure contributes significantly to the overall drive through the curvature term and the Pfirsch-Schluter current. These results demonstrate potential of QAS and QOS for disruption-free operations at high-beta without a close-fitting conducting wall and feedback stabilization.

An Alternating Current Electroosmotic Pump Based on Conical Nanopore Membranes.

PubMed

Wu, Xiaojian; Ramiah Rajasekaran, Pradeep; Martin, Charles R

2016-04-26

Electroosmotic flow (EOF) is used to pump solutions through microfluidic devices and capillary electrophoresis columns. We describe here an EOF pump based on membrane EOF rectification, an electrokinetic phenomenon we recently described. EOF rectification requires membranes with asymmetrically shaped pores, and conical pores in a polymeric membrane were used here. We show here that solution flow through the membrane can be achieved by applying a symmetrical sinusoidal voltage waveform across the membrane. This is possible because the alternating current (AC) carried by ions through the pore is rectified, and we previously showed that rectified currents yield EOF rectification. We have investigated the effect of both the magnitude and frequency of the voltage waveform on flow rate through the membrane, and we have measured the maximum operating pressure. Finally, we show that operating in AC mode offers potential advantages relative to conventional DC-mode EOF pumps.

Development and testing of a 180-volt dc electronic circuit breaker with a 335-ampere carry and 1200-ampere interrupt rating

NASA Technical Reports Server (NTRS)

Brush, A. S.; Phillips, R. L.

1991-01-01

NASA Lewis Research Center and associated contractors have conducted a program to assess the potential requirements for a high-current switch to conceptually design a switch using the best existing technology, and to build and demonstrate a breadboard which meets the requirements. The result is the high current remote bus isolator (HRBI). The HRBI is rated at 180 V dc, 335 A continuous with a 1200 A interrupt rating. It also incorporates remote-control and protective features called for by the Space Station Freedom PMAD dc test bed design. Two breadboard 335 A circuit breakers were built and tested that demonstrate a promising concept of paralleled current-limiting modules. The units incorporated all control and protective features required by advanced aerospace power systems. Component stresses in each unit were determined by design, and are consistent with a life of many thousands of fault operations.

Setup for potential bias experiments on the Saha Institute of Nuclear Physics tokamak

NASA Astrophysics Data System (ADS)

Ghosh, J.; Pal, R.; Chattopadhyay, P. K.

1999-12-01

An experimental setup for studying the influence of the radial electric field on very low qa plasma on the Saha Institute of Nuclear Physics tokamak is presented. A high current, high voltage pulsed power supply, using a semiconductor controlled rectifier (SCR) as a dc switch is developed and used to bias a tungsten electrode inserted inside the plasma. The electrode's exposed length and its position inside the plasma are controlled by a double bellows assembly to optimize the electrode-exposed length. We show that using the force commutation method to turn the SCR off to get the power pulse desired has good potential for carrying out similar kinds of studies, especially in a low budget small tokamak.

Vacuum vapor deposition: A spinoff of space welding development

NASA Technical Reports Server (NTRS)

Poorman, R. M.

1991-01-01

A vapor deposition process has been defined through a spinoff effort of space welding development. In this development for welding in a space environment, a hollow electrode was used to add gas precisely at the welding arc. This provides gas for ionization which carries the welding arc current. During this welding development metal vapor coatings were observed. These coatings are unique in that they are produced by a new process. Some coatings produced and the potential of this new and innovative vapor deposition process are characterized. Advantages over prior art are discussed.

Current status of biotechnology in Slovakia.

PubMed

Stuchlík, Stanislav; Turna, Ján

2013-07-01

The United Nations Convention on Biological Diversity defines biotechnology as: 'Any technological application that uses biological systems, living organisms, or derivatives thereof, to make or modify products or processes for specific use.' In other words biotechnology is 'application of scientific and technical advances in life science to develop commercial products' or briefly 'the use of molecular biology for useful purposes'. This short overview is about different branches of biotechnology carried out in Slovakia and it shows that Slovakia has a good potential for further development of modern biotechnologies. Copyright © 2013 Elsevier Ltd. All rights reserved.

In search of the dimensions of an incandescent light bulb filament

NASA Astrophysics Data System (ADS)

Ladino, Luis A.; Rondón, Hermilda S.

2018-05-01

The purpose of this paper is to present and discuss an alternative solution to an experimental problem given to high school students in the XXII Ibero-American Physics Olympiad held by Colombia this year. From the measurements of electric current and potential difference across a small tungsten filament lamp students should find the dimensions of its filament. The results obtained are compared with the ones measured directly. This challenging and low-cost experiment can be easily implemented and carried out in any introductory physics laboratory courses.

Smokers' attitudes and support for e-cigarette policies and regulation in the USA.

PubMed

Wackowski, Olivia A; Delnevo, Cristine D

2015-11-01

In April 2014, the Food and Drug Administration (FDA) proposed a rule to extend its tobacco regulatory authority to e-cigarettes, which have been unregulated and growing in use since their 2006-2007 US introduction. The FDA will issue a final rule based on comments and data received from researchers, tobacco companies and the public. We aimed to present data about current smokers' awareness of and attitudes towards potential e-cigarette regulation and various policies in the USA. We conducted a cross-sectional online e-cigarette focused survey of 519 adult current smokers in April 2014, before the FDA's proposed rule was announced. Participants were recruited from a private research panel (GFK's Knowledge Networks) designed to be representative of the US population. The majority of respondents (62.5%) did not know that e-cigarettes are unregulated by the FDA but agreed that e-cigarettes should be regulated by the FDA for safety and quality (83.5%), carry warning labels about their potential risks (86.6%) and have the same legal age of sale as other tobacco (87.7%). Support was similarly high among current e-cigarette users. Support was substantial though lower overall for policies to restrict e-cigarette indoor use (41.2%), flavouring (44.3%) and advertising (55.5%), and was negatively associated with current e-cigarette use. Support for many e-cigarette regulatory policies is strong among smokers, including for policies that the FDA has recently proposed and potential future regulations. States considering indoor e-cigarette restrictions should know that a substantial number of current smokers support such regulations. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Performance assessment for low-level waste disposal in the UK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashworth, A.B.

1995-12-31

British Nuclear Fuels plc (BNFL) operate a site for the disposal of Low Level Radioactive Waste at Drigg in West Cumbria, in North-West England. HMIP are responsible for the regulation of the site with regard to environmental discharges of radioactive materials, both operational and post-closure. This paper is concerned with post-closure matters only. Two post-closure performance assessments have been carried out for this site: one by the National Radiological Protection Board (NRPB) in 1987; and a subsequent one carried out on behalf of HMIP, completed in 1991. Currently, BNFL are preparing a Safety Case for continued operation of the Driggmore » site, and it expected that the core of this Case will comprise BNFL`s own analysis of post-closure performance. HMIP has developed procedures for the assessment of this Case, based upon experience of the previous Drigg assessments, and also upon the experience of similar work carried out in the assessment of Intermediate Level Waste (ILW) disposal at both deep and shallow potential sites. This paper describes the more important features of these procedures.« less

A Multifunctional Hot Structure Heatshield Concept for Planetary Entry

NASA Technical Reports Server (NTRS)

Walker, Sandra P.; Daryabeigi, Kamran; Samareh, Jamshid A.; Wagner, Robert; Waters, Allen

2015-01-01

A multifunctional hot structure heatshield concept is being developed to provide technology enhancements with significant benefits compared to the current state-of-the-art heatshield technology. These benefits can potentially enable future planetary missions. The concept is unique in integrating the function of the thermal protection system with the primary load carrying structural component. An advanced carbon-carbon material system has been evaluated for the load carrying structure, which will be utilized on the outer surface of the heatshield, and thus will operate as a hot structure exposed to the severe aerodynamic heating associated with planetary entry. Flexible, highly efficient blanket insulation is sized for use underneath the hot structure to maintain required operational internal temperatures. The approach followed includes developing preliminary designs to demonstrate feasibility of the concept and benefits over a traditional, baseline design. Where prior work focused on a concept for an Earth entry vehicle, the current efforts presented here are focused on developing a generic heatshield model and performing a trade study for a Mars entry application. This trade study includes both structural and thermal evaluation. The results indicate that a hot structure concept is a feasible alternative to traditional heatshields and may offer advantages that can enable future entry missions.

Design, fabrication, and testing of a low frequency MEMS piezoelectromagnetic energy harvester

NASA Astrophysics Data System (ADS)

Fernandes, Egon; Martin, Blake; Rua, Isabel; Zarabi, Sid; Debéda, Hélène; Nairn, David; Wei, Lan; Salehian, Armaghan

2018-03-01

This paper details a power solution for smart grid applications to replace batteries by harvesting the electromagnetic energy from a current-carrying wire. A MEMS piezoelectromagnetic energy harvester has been fabricated using PZT screen-printing technology with a centrally-supported meandering geometry. The energy harvesting device employs a symmetric geometry to increase its power output by reducing the effects of the torsional modes and the resultant overall strain nodes in the system subsequently reduce the complexities for the electrode fabrication. The unit is modelled using COMSOL to determine mode shapes and frequency response functions. A 12.7 mm by 14.7 mm unit is fabricated by screen-printing 75 μm-thick PZT on a stainless steel substrate and then experimentally tested to validate the FEA results. Experimentally, the harvester is shown to produce 9 μW from a wire carrying 7 A while operating at a distance of 6.5 mm from the wire. The design of the current work results in a greater normalized power density than other MEMS based piezoelectromagnetic devices and shows great potential relative to larger devices that use bulk or thin film piezoelectrics.

Potentiostatic pulse-deposition of calcium phosphate on magnesium alloy for temporary implant applications--an in vitro corrosion study.

PubMed

Kannan, M Bobby; Wallipa, O

2013-03-01

In this study, a magnesium alloy (AZ91) was coated with calcium phosphate using potentiostatic pulse-potential and constant-potential methods and the in vitro corrosion behaviour of the coated samples was compared with the bare metal. In vitro corrosion studies were carried out using electrochemical impedance spectroscopy and potentiodynamic polarization in simulated body fluid (SBF) at 37 °C. Calcium phosphate coatings enhanced the corrosion resistance of the alloy, however, the pulse-potential coating performed better than the constant-potential coating. The pulse-potential coating exhibited ~3 times higher polarization resistance than that of the constant-potential coating. The corrosion current density obtained from the potentiodynamic polarization curves was significantly less (~60%) for the pulse-deposition coating as compared to the constant-potential coating. Post-corrosion analysis revealed only slight corrosion on the pulse-potential coating, whereas the constant-potential coating exhibited a large number of corrosion particles attached to the coating. The better in vitro corrosion performance of the pulse-potential coating can be attributed to the closely packed calcium phosphate particles. Copyright © 2012 Elsevier B.V. All rights reserved.

Streaming current magnetic fields in a charged nanopore.

PubMed

Mansouri, Abraham; Taheri, Peyman; Kostiuk, Larry W

2016-11-11

Magnetic fields induced by currents created in pressure driven flows inside a solid-state charged nanopore were modeled by numerically solving a system of steady state continuum partial differential equations, i.e., Poisson, Nernst-Planck, Ampere and Navier-Stokes equations (PNPANS). This analysis was based on non-dimensional transport governing equations that were scaled using Debye length as the characteristic length scale, and applied to a finite length cylindrical nano-channel. The comparison of numerical and analytical studies shows an excellent agreement and verified the magnetic fields density both inside and outside the nanopore. The radially non-uniform currents resulted in highly non-uniform magnetic fields within the nanopore that decay as 1/r outside the nanopore. It is worth noting that for either streaming currents or streaming potential cases, the maximum magnetic field occurred inside the pore in the vicinity of nanopore wall, as opposed to a cylindrical conductor that carries a steady electric current where the maximum magnetic fields occur at the perimeter of conductor. Based on these results, it is suggested and envisaged that non-invasive external magnetic fields readouts generated by streaming/ionic currents may be viewed as secondary electronic signatures of biomolecules to complement and enhance current DNA nanopore sequencing techniques.

Streaming current magnetic fields in a charged nanopore

NASA Astrophysics Data System (ADS)

Mansouri, Abraham; Taheri, Peyman; Kostiuk, Larry W.

2016-11-01

Magnetic fields induced by currents created in pressure driven flows inside a solid-state charged nanopore were modeled by numerically solving a system of steady state continuum partial differential equations, i.e., Poisson, Nernst-Planck, Ampere and Navier-Stokes equations (PNPANS). This analysis was based on non-dimensional transport governing equations that were scaled using Debye length as the characteristic length scale, and applied to a finite length cylindrical nano-channel. The comparison of numerical and analytical studies shows an excellent agreement and verified the magnetic fields density both inside and outside the nanopore. The radially non-uniform currents resulted in highly non-uniform magnetic fields within the nanopore that decay as 1/r outside the nanopore. It is worth noting that for either streaming currents or streaming potential cases, the maximum magnetic field occurred inside the pore in the vicinity of nanopore wall, as opposed to a cylindrical conductor that carries a steady electric current where the maximum magnetic fields occur at the perimeter of conductor. Based on these results, it is suggested and envisaged that non-invasive external magnetic fields readouts generated by streaming/ionic currents may be viewed as secondary electronic signatures of biomolecules to complement and enhance current DNA nanopore sequencing techniques.

Electronic Current Transducer (ECT) for high voltage dc lines

NASA Astrophysics Data System (ADS)

Houston, J. M.; Peters, P. H., Jr.; Summerayes, H. R., Jr.; Carlson, G. J.; Itani, A. M.

1980-02-01

The development of a bipolar electronic current transducer (ECT) for measuring the current in a high voltage dc (HVDC) power line at line potential is discussed. The design and construction of a free standing ECT for use on a 400 kV line having a nominal line current of 2000 A is described. Line current is measured by a 0.0001 ohm shunt whose voltage output is sampled by a 14 bit digital data link. The high voltage interface between line and ground is traversed by optical fibers which carry digital light signals as far as 300 m to a control room where the digital signal is converted back to an analog representation of the shunt voltage. Two redundant electronic and optical data links are used in the prototype. Power to operate digital and optical electronics and temperature controlling heaters at the line is supplied by a resistively and capacitively graded 10 stage cascade of ferrite core transformers located inside the hollow, SF6 filled, porcelain support insulator. The cascade is driven by a silicon controlled rectifier inverter which supplies about 100 W of power at 30 kHz.

D242N, a KV7.1 LQTS mutation uncovers a key residue for IKs voltage dependence.

PubMed

Moreno, Cristina; Oliveras, Anna; Bartolucci, Chiara; Muñoz, Carmen; de la Cruz, Alicia; Peraza, Diego A; Gimeno, Juan R; Martín-Martínez, Mercedes; Severi, Stefano; Felipe, Antonio; Lambiase, Pier D; Gonzalez, Teresa; Valenzuela, Carmen

2017-09-01

K V 7.1 and KCNE1 co-assemble to give rise to the I Ks current, one of the most important repolarizing currents of the cardiac action potential. Its relevance is underscored by the identification of >500 mutations in K V 7.1 and, at least, 36 in KCNE1, that cause Long QT Syndrome (LQTS). The aim of this study was to characterize the biophysical and cellular consequences of the D242N K V 7.1 mutation associated with the LQTS. The mutation is located in the S4 transmembrane segment, within the voltage sensor of the K V 7.1 channel, disrupting the conserved charge balance of this region. Perforated patch-clamp experiments show that, unexpectedly, the mutation did not disrupt the voltage-dependent activation but it removed the inactivation and slowed the activation kinetics of D242N K V 7.1 channels. Biotinylation of cell-surface protein and co-immunoprecipitation experiments revealed that neither plasma membrane targeting nor co-assembly between K V 7.1 and KCNE1 was altered by the mutation. However, the association of D242N K V 7.1 with KCNE1 strongly shifted the voltage dependence of activation to more depolarized potentials (+50mV), hindering I Ks current at physiologically relevant membrane potentials. Both functional and computational analysis suggest that the clinical phenotype of the LQTS patients carrying the D242N mutation is due to impaired action potential adaptation to exercise and, in particular, to increase in heart rate. Moreover, our data identify D242 aminoacidic position as a potential residue involved in the KCNE1-mediated regulation of the voltage dependence of activation of the K V 7.1 channel. Copyright © 2017 Elsevier Ltd. All rights reserved.

Arc Discharges of a Pure Carbon Strip Affected by Dynamic Contact Force during Current-Carrying Sliding

PubMed Central

Zhang, Yanyan; Zhang, Yongzhen

2018-01-01

Arc discharges of a pure carbon strip induced by dynamic contact force were studied on a pin-on-disk tribometer. It was found that arc discharges were produced periodically in accordance with the period of the dynamic contact force. The arcing rate of the pure carbon strip increased with an increase of frequency f and amplitude B, which led to a decrease of current-carrying quality. These influences at high velocities became much more significant. A critical point of the arcing rate at around 2% was detected. Lower than 2%, the pure carbon strip was able to maintain its excellent current-carrying capability; higher than this point, the current-carrying quality deteriorated abruptly. SEM and XPS analysis show that the element Cu detected on the worn surface at lower arcing rates was metal Cu. CuO was found at higher arcing rates. This indicated that the wear mechanism transferred from mechanical wear to arc erosion with the increase of the arcing rate. PMID:29762496

Arc Discharges of a Pure Carbon Strip Affected by Dynamic Contact Force during Current-Carrying Sliding.

PubMed

Zhang, Yanyan; Zhang, Yongzhen; Song, Chenfei

2018-05-15

Arc discharges of a pure carbon strip induced by dynamic contact force were studied on a pin-on-disk tribometer. It was found that arc discharges were produced periodically in accordance with the period of the dynamic contact force. The arcing rate of the pure carbon strip increased with an increase of frequency f and amplitude B , which led to a decrease of current-carrying quality. These influences at high velocities became much more significant. A critical point of the arcing rate at around 2% was detected. Lower than 2%, the pure carbon strip was able to maintain its excellent current-carrying capability; higher than this point, the current-carrying quality deteriorated abruptly. SEM and XPS analysis show that the element Cu detected on the worn surface at lower arcing rates was metal Cu. CuO was found at higher arcing rates. This indicated that the wear mechanism transferred from mechanical wear to arc erosion with the increase of the arcing rate.

E-cigarettes and Urologic Health: A Collaborative Review of Toxicology, Epidemiology, and Potential Risks.

PubMed

Bourke, Liam; Bauld, Linda; Bullen, Christopher; Cumberbatch, Marcus; Giovannucci, Edward; Islami, Farhad; McRobbie, Hayden; Silverman, Debra T; Catto, James W F

2017-06-01

Use of electronic cigarettes (ECs) is on the rise in most high-income countries. Smoking conventional cigarettes is a known risk factor for urologic malignancy incidence, progression, and mortality, as well as for other urologic health indicators. The potential impact of EC use on urologic health is therefore of clinical interest to the urology community. To review the available data on current EC use, including potential benefits in urologic patients, potential issues linked to toxicology of EC constituents, and how this might translate into urologic health risks. A Medline search was carried out in August 2016 for studies reporting urologic health outcomes and EC use. Snowballing techniques were also used to identify relevant studies from recent systematic reviews. A narrative synthesis of data around EC health outcomes, toxicology, and potential use in smoking cessation and health policy was carried out. We found no studies to date that have been specifically designed to prospectively assess urologic health risks, even in an observational setting. Generating such data would be an important contribution to the debate on the role of ECs in public health and clinical practice. There is evidence from a recent Cochrane review of RCTs that ECs can support smoking cessation. There are emerging data indicating that potentially harmful components of ECs such as tobacco-specific nitrosamines, polyaromatic hydrocarbons, and heavy metals could be linked to possible urologic health risks. ECs might be a useful tool to encourage cessation of conventional cigarette smoking. However, data collection around the specific impact of ECs on urologic health is needed to clarify the possible patient benefits, outcomes, and adverse events. While electronic cigarettes might help some people to stop smoking, their overall impact on urologic health is not clear. Copyright © 2017 European Association of Urology. All rights reserved.

Water quality monitoring: A comparative case study of municipal and Curtin Sarawak's lake samples

NASA Astrophysics Data System (ADS)

Anand Kumar, A.; Jaison, J.; Prabakaran, K.; Nagarajan, R.; Chan, Y. S.

2016-03-01

In this study, particle size distribution and zeta potential of the suspended particles in municipal water and lake surface water of Curtin Sarawak's lake were compared and the samples were analysed using dynamic light scattering method. High concentration of suspended particles affects the water quality as well as suppresses the aquatic photosynthetic systems. A new approach has been carried out in the current work to determine the particle size distribution and zeta potential of the suspended particles present in the water samples. The results for the lake samples showed that the particle size ranges from 180nm to 1345nm and the zeta potential values ranges from -8.58 mV to -26.1 mV. High zeta potential value was observed in the surface water samples of Curtin Sarawak's lake compared to the municipal water. The zeta potential values represent that the suspended particles are stable and chances of agglomeration is lower in lake water samples. Moreover, the effects of physico-chemical parameters on zeta potential of the water samples were also discussed.

An electrical analogy to Mie scattering

PubMed Central

Caridad, José M.; Connaughton, Stephen; Ott, Christian; Weber, Heiko B.; Krstić, Vojislav

2016-01-01

Mie scattering is an optical phenomenon that appears when electromagnetic waves, in particular light, are elastically scattered at a spherical or cylindrical object. A transfer of this phenomenon onto electron states in ballistic graphene has been proposed theoretically, assuming a well-defined incident wave scattered by a perfectly cylindrical nanometer scaled potential, but experimental fingerprints are lacking. We present an experimental demonstration of an electrical analogue to Mie scattering by using graphene as a conductor, and circular potentials arranged in a square two-dimensional array. The tabletop experiment is carried out under seemingly unfavourable conditions of diffusive transport at room-temperature. Nonetheless, when a canted arrangement of the array with respect to the incident current is chosen, cascaded Mie scattering results robustly in a transverse voltage. Its response on electrostatic gating and variation of potentials convincingly underscores Mie scattering as underlying mechanism. The findings presented here encourage the design of functional electronic metamaterials. PMID:27671003

Multireference configuration interaction calculations of the first six ionization potentials of the uranium atom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bross, David H.; Parmar, Payal; Peterson, Kirk A., E-mail: kipeters@wsu.edu

The first 6 ionization potentials (IPs) of the uranium atom have been calculated using multireference configuration interaction (MRCI+Q) with extrapolations to the complete basis set limit using new all-electron correlation consistent basis sets. The latter was carried out with the third-order Douglas-Kroll-Hess Hamiltonian. Correlation down through the 5s5p5d electrons has been taken into account, as well as contributions to the IPs due to the Lamb shift. Spin-orbit coupling contributions calculated at the 4-component Kramers restricted configuration interaction level, as well as the Gaunt term computed at the Dirac-Hartree-Fock level, were added to the best scalar relativistic results. The final ionizationmore » potentials are expected to be accurate to at least 5 kcal/mol (0.2 eV) and thus more reliable than the current experimental values of IP{sub 3} through IP{sub 6}.« less

Micro- and macro-scale petrophysical characterization of potential reservoir units from the Northern Israel

NASA Astrophysics Data System (ADS)

Haruzi, Peleg; Halisch, Matthias; Katsman, Regina; Waldmann, Nicolas

2016-04-01

Lower Cretaceous sandstone serves as hydrocarbon reservoir in some places over the world, and potentially in Hatira formation in the Golan Heights, northern Israel. The purpose of the current research is to characterize the petrophysical properties of these sandstone units. The study is carried out by two alternative methods: using conventional macroscopic lab measurements, and using CT-scanning, image processing and subsequent fluid mechanics simulations at a microscale, followed by upscaling to the conventional macroscopic rock parameters (porosity and permeability). Comparison between the upscaled and measured in the lab properties will be conducted. The best way to upscale the microscopic rock characteristics will be analyzed based the models suggested in the literature. Proper characterization of the potential reservoir will provide necessary analytical parameters for the future experimenting and modeling of the macroscopic fluid flow behavior in the Lower Cretaceous sandstone.

A new biphasic osteoinductive calcium composite material with a negative Zeta potential for bone augmentation

PubMed Central

Smeets, Ralf; Kolk, Andreas; Gerressen, Marcus; Driemel, Oliver; Maciejewski, Oliver; Hermanns-Sachweh, Benita; Riediger, Dieter; Stein, Jamal M

2009-01-01

The aim of the present study was to analyze the osteogenic potential of a biphasic calcium composite material (BCC) with a negative surface charge for maxillary sinus floor augmentation. In a 61 year old patient, the BCC material was used in a bilateral sinus floor augmentation procedure. Six months postoperative, a bone sample was taken from the augmented regions before two titanium implants were inserted at each side. We analyzed bone neoformation by histology, bone density by computed tomography, and measured the activity of voltage-activated calcium currents of osteoblasts and surface charge effects. Control orthopantomograms were carried out five months after implant insertion. The BCC was biocompatible and replaced by new mineralized bone after being resorbed completely. The material demonstrated a negative surface charge (negative Zeta potential) which was found to be favorable for bone regeneration and osseointegration of dental implants. PMID:19523239

High frequency lateral flow affinity assay using superparamagnetic nanoparticles

NASA Astrophysics Data System (ADS)

Lago-Cachón, D.; Rivas, M.; Martínez-García, J. C.; Oliveira-Rodríguez, M.; Blanco-López, M. C.; García, J. A.

2017-02-01

Lateral flow assay is one of the simplest and most extended techniques in medical diagnosis for point-of-care testing. Although it has been traditionally a positive/negative test, some work has been lately done to add quantitative abilities to lateral flow assay. One of the most successful strategies involves magnetic beads and magnetic sensors. Recently, a new technique of superparamagnetic nanoparticle detection has been reported, based on the increase of the impedance induced by the nanoparticles on a RF-current carrying copper conductor. This method requires no external magnetic field, which reduces the system complexity. In this work, nitrocellulose membranes have been installed on the sensor, and impedance measurements have been carried out during the sample diffusion by capillarity along the membrane. The impedance of the sensor changes because of the presence of magnetic nanoparticles. The results prove the potentiality of the method for point-of-care testing of biochemical substances and nanoparticle capillarity flow studies.

Solar Polar ORbit Telescope (SPORT): A Potential Heliophysics Mission of China

NASA Astrophysics Data System (ADS)

Liu, Ying

We describe a spacecraft mission, named Solar Polar ORbit Telescope (SPORT), which is currently under a scientific and engineering background study in China. SPORT was originally proposed in 2004 by the National Space Science Center, Chinese Academy of Sciences. It will carry a suite of remote-sensing and in-situ instruments to observe coronal mass ejections (CMEs), solar high-latitude magnetism, and the fast solar wind from a polar orbit around the Sun. It is intended to be the first mission that carries remote-sensing instruments from a high-latitude orbit around the Sun and the first mission that could measure solar high-latitude magnetism. The first extended view of the polar region of the Sun and the ecliptic plane enabled by SPORT will provide a unique opportunity to study CME propagation through the inner heliosphere and solar high-latitude magnetism giving rise to eruptions and the fast solar wind.

Experimental manipulation of avian social structure reveals segregation is carried over across contexts

PubMed Central

Firth, Josh A.; Sheldon, Ben C.

2015-01-01

Our current understanding of animal social networks is largely based on observations or experiments that do not directly manipulate associations between individuals. Consequently, evidence relating to the causal processes underlying such networks is limited. By imposing specified rules controlling individual access to feeding stations, we directly manipulated the foraging social network of a wild bird community, thus demonstrating how external factors can shape social structure. We show that experimentally imposed constraints were carried over into patterns of association at unrestricted, ephemeral food patches, as well as at nesting sites during breeding territory prospecting. Hence, different social contexts can be causally linked, and constraints at one level may have consequences that extend into other aspects of sociality. Finally, the imposed assortment was lost following the cessation of the experimental manipulation, indicating the potential for previously perturbed social networks of wild animals to recover from segregation driven by external constraints. PMID:25652839

Assessment of errors in static electrical impedance tomography with adjacent and trigonometric current patterns.

PubMed

Kolehmainen, V; Vauhkonen, M; Karjalainen, P A; Kaipio, J P

1997-11-01

In electrical impedance tomography (EIT), difference imaging is often preferred over static imaging. This is because of the many unknowns in the forward modelling which make it difficult to obtain reliable absolute resistivity estimates. However, static imaging and absolute resistivity values are needed in some potential applications of EIT. In this paper we demonstrate by simulation the effects of different error components that are included in the reconstruction of static EIT images. All simulations are carried out in two dimensions with the so-called complete electrode model. Errors that are considered are the modelling error in the boundary shape of an object, errors in the electrode sizes and localizations and errors in the contact impedances under the electrodes. Results using both adjacent and trigonometric current patterns are given.

Evaluation of eddy current and magnetic techniques for inspecting rebars in bridge barrier rails

NASA Astrophysics Data System (ADS)

Lo, C. C. H.; Nakagawa, N.

2013-01-01

This paper reports on a feasibility study of using eddy current (EC) and magnetic flux leakage (MFL) methods to detect corrosion damage in rebars that anchor concrete barrier rails to the road deck of bridge structures. EC and MFL measurements were carried out on standalone rebars with and without artificial defects of 25% and 50% material loss, using a commercial EC-based rebar locator and a MFL system that was developed using giant magnetoresistance sensors to detect leakage fluxes from the defects. Both techniques can readily detect the defects at a distance of 2.5″ (63.5 mm). The amplitudes of the EC and MFL signals vary monotonically with the amount of material loss, indicating the potential of using the techniques to quantify material loss of standalone rebars.

Graphene-Nanodiamond Heterostructures and their application to High Current Devices

PubMed Central

Zhao, Fang; Vrajitoarea, Andrei; Jiang, Qi; Han, Xiaoyu; Chaudhary, Aysha; Welch, Joseph O.; Jackman, Richard B.

2015-01-01

Graphene on hydrogen terminated monolayer nanodiamond heterostructures provides a new way to improve carrier transport characteristics of the graphene, offering up to 60% improvement when compared with similar graphene on SiO2/Si substrates. These heterostructures offers excellent current-carrying abilities whilst offering the prospect of a fast, low cost and easy methodology for device applications. The use of ND monolayers is also a compatible technology for the support of large area graphene films. The nature of the C-H bonds between graphene and H-terminated NDs strongly influences the electronic character of the heterostructure, creating effective charge redistribution within the system. Field effect transistors (FETs) have been fabricated based on this novel herterostructure to demonstrate device characteristics and the potential of this approach. PMID:26350107

FAST satellite observations of large-amplitude solitary structures

NASA Astrophysics Data System (ADS)

Ergun, R. E.; Carlson, C. W.; McFadden, J. P.; Mozer, F. S.; Delory, G. T.; Peria, W.; Chaston, C. C.; Temerin, M.; Roth, I.; Muschietti, L.; Elphic, R.; Strangeway, R.; Pfaff, R.; Cattell, C. A.; Klumpar, D.; Shelley, E.; Peterson, W.; Moebius, E.; Kistler, L.

We report observations of “fast solitary waves” that are ubiquitous in downward current regions of the mid-altitude auroral zone. The single-period structures have large amplitudes (up to 2.5 V/m), travel much faster than the ion acoustic speed, carry substantial potentials (up to ∼100 Volts), and are associated with strong modulations of energetic electron fluxes. The amplitude and speed of the structures distinguishes them from ion-acoustic solitary waves or weak double layers. The electromagnetic signature appears to be that of an positive charge (electron hole) traveling anti-earthward. We present evidence that the structures are in or near regions of magnetic-field-aligned electric fields and propose that these nonlinear structures play a key role in supporting parallel electric fields in the downward current region of the auroral zone.

Cobalt chloride administration in athletes: a new perspective in blood doping?

PubMed

Lippi, G; Franchini, M; Guidi, G C

2005-11-01

Blood doping is an illegal and unfair way of enhancing athletic performance by increasing the oxygen carrying capacity of the blood. Currently used methods usually involve stimulation of erythropoiesis. Gene therapy targeting the hypoxia inducible factor pathway may be an attractive alternative to traditional blood doping techniques. Hypoxia activates a large number of genes with essential roles in cell and tissue adaptation to low oxygen. Cobalt chloride is a well established chemical inducer of hypoxia-like responses such as erythropoiesis. Cobalt supplementation is not banned and therefore would not be detected by current anti-doping testing. Although there is as yet no direct or anecdotal evidence of cobalt chloride administration to athletes, its use should be warned against as being not only unfair but potentially dangerous.

Novel failure mechanism and improvement for split-gate trench MOSFET with large current under unclamped inductive switch stress

NASA Astrophysics Data System (ADS)

Tian, Ye; Yang, Zhuo; Xu, Zhiyuan; Liu, Siyang; Sun, Weifeng; Shi, Longxing; Zhu, Yuanzheng; Ye, Peng; Zhou, Jincheng

2018-04-01

In this paper, a novel failure mechanism under unclamped inductive switch (UIS) for Split-Gate Trench Metal Oxide Semiconductor Field Effect Transistor (MOSFET) with large current is investigated. The device sample is tested and analyzed in detail. The simulation results demonstrate that the nonuniform potential distribution of the source poly should be responsible for the failure. Three structures are proposed and verified available to improve the device UIS ruggedness by TCAD simulation. The best one of the structures the device with source metal inserting into source poly through contacts in the field oxide is carried out and measured. The results demonstrate that the optimized structure can balance the trade-off between the UIS ruggedness and the static characteristics.

A Game Theoretical Approach to Hacktivism: Is Attack Likelihood a Product of Risks and Payoffs?

PubMed

Bodford, Jessica E; Kwan, Virginia S Y

2018-02-01

The current study examines hacktivism (i.e., hacking to convey a moral, ethical, or social justice message) through a general game theoretic framework-that is, as a product of costs and benefits. Given the inherent risk of carrying out a hacktivist attack (e.g., legal action, imprisonment), it would be rational for the user to weigh these risks against perceived benefits of carrying out the attack. As such, we examined computer science students' estimations of risks, payoffs, and attack likelihood through a game theoretic design. Furthermore, this study aims at constructing a descriptive profile of potential hacktivists, exploring two predicted covariates of attack decision making, namely, peer prevalence of hacking and sex differences. Contrary to expectations, results suggest that participants' estimations of attack likelihood stemmed solely from expected payoffs, rather than subjective risks. Peer prevalence significantly predicted increased payoffs and attack likelihood, suggesting an underlying descriptive norm in social networks. Notably, we observed no sex differences in the decision to attack, nor in the factors predicting attack likelihood. Implications for policymakers and the understanding and prevention of hacktivism are discussed, as are the possible ramifications of widely communicated payoffs over potential risks in hacking communities.

CO2 heat pumps for commercial building applications with simultaneous heating and cooling demand

NASA Astrophysics Data System (ADS)

Dharkar, Supriya

Many commercial buildings, including data centers, hotels and hospitals, have a simultaneous heating and cooling demand depending on the season, occupation and auxiliary equipment. A data center on the Purdue University, West Lafayette campus is used as a case study. The electrical equipment in data centers produce heat, which must be removed to prevent the equipment temperature from rising to a certain level. With proper integration, this heat has the potential to be used as a cost-effective energy source for heating the building in which the data center resides or the near-by buildings. The proposed heat pump system utilizes carbon dioxide with global warming potential of 1, as the refrigerant. System simulations are carried out to determine the feasibility of the system for a 12-month period. In addition, energy, environmental and economic analyses are carried out to show the benefits of this alternative technology when compared to the conventional system currently installed in the facility. Primary energy savings of ~28% to ~61%, a payback period of 3 to 4.5 years and a decrease in the environmental impact value by ~36% makes this system an attractive option. The results are then extended to other commercial buildings.

Synthesis, characterization of novel chitosan based water dispersible polyurethanes and their potential deployment as antibacterial textile finish.

PubMed

Arshad, Noureen; Zia, Khalid Mahmood; Jabeen, Farukh; Anjum, Muhammad Naveed; Akram, Nadia; Zuber, Mohammad

2018-05-01

Our current research work comprised of synthesis of a series of novel chitosan based water dispersible polyurethanes. The synthesis was carried out in three steps, in first step, the NCO end capped PU-prepolymer was formed through the reaction between Polyethylene glycol (PEG) (Mn = 600), Dimethylolpropionic acid (DMPA) and Isophorone diisocyanate (IPDI). In second step, the neutralization step was carried out by using Triethylamine (TEA) which resulted the formation of neutralized NCO terminated PU-prepolymer, after that the last step chain extension was performed by the addition of chitosan and followed the formation of dispersion by adding calculated amount of water. The proposed structure of CS-WDPUs was confirmed by using FTIR technique. The antimicrobial activities of the plain weave poly-cotton printed and dyed textile swatches after application of CS-WDPUs were also evaluated. The results showed that the chitosan incorporation in to PU backbone has markedly enhanced the antibacterial activity of WDPUs. These synthesized CS-WDPUs are eco-friendly antimicrobial finishes (using natural bioactive agents such as chitosan) with potential applications on polyester/cotton textiles. Copyright © 2018 Elsevier B.V. All rights reserved.

Supply chain and marketing of sea grapes, Caulerpa racemosa (Forsskål) J. Agardh (Chlorophyta: Caulerpaceae) in Fiji, Samoa and Tonga.

PubMed

Morris, C; Bala, S; South, G R; Lako, J; Lober, M; Simos, T

2014-01-01

This report describes for the first time the supply chain of Caulerpa racemosa in three Pacific Island countries. The harvesting and marketing of C. racemosa are important subsistence activities for villagers in Fiji and Samoa, less so in Tonga. At least 150 harvesters are involved in Fiji, some 100 in Samoa and only a handful in Tonga. The annual combined crop is of some 123 t valued at around US$266,492. In Fiji, it is projected that supply does not meet local demand and there is a potential export market that is currently operating at a pilot project level. In Samoa, the supply is considered adequate for the current market. In Tonga, harvesting is carried out by a few families and supplies a niche market in that country. The possibilities of field cultivation of Caulerpa have been explored but, at present, with only limited success in Samoa. The supply chain is simple in all three countries, and only in Fiji are middlemen involved in the distribution process. The limitations for marketing include the fact that only a few sites supply most of the crop in all the three countries, that all sites need to be conserved through sustainable harvesting methods, the short shelf life of the crop and a lack of information on the carrying capacity of harvest sites. Caulerpa remains a crop that fulfils a niche market but has the potential to be scaled up for additional livelihood development in the future.

Diffusion and Electric Mobility of Ions within Isolated Cuticles of Citrus aurantium 1

PubMed Central

Tyree, Melvin T.; Wescott, Charles R.; Tabor, Christopher A.

1991-01-01

We report a new method for measuring cation and anion permeability across cuticles of sour orange, Citrus aurantium, leaves. The method requires the measurement of two electrical parameters: the diffusion potential arising when the two sides of the cuticle are bathed in unequal concentrations of a Cl− salt; and the electrical conductance of the cuticle measured at a salt concentration equal to the average of that used in the diffusion-potential measurement. The permeabilities of H+, Li+, Na+, K+, and Cs+ ranged from 2 × 10−8 to 0.6 × 10−8 meters per second when cuticles were bathed in 2 moles per cubic meter Cl− salts. The permeability of Cl− was 3 × 10−9 meters per second. The permeability of Li+, Na+, and K+ was about five times less when measured in 500 moles per cubic meter Cl− salts. We also report an asymmetry in cuticle-conductance values depending on the magnitude and the direction of current flow. The asymmetry disappears at low current-pulse magnitude and increases linearly with the magnitude of the current pulse. This phenomenon is explained in terms of transport-number effects in a bilayer model of the cuticle. Conductance is not augmented by current carried by exchangeable cations in cuticles; conductance is rate limited by the outer waxy layer of the cuticle. PMID:16668382

A linear helicon plasma device with controllable magnetic field gradient.

PubMed

Barada, Kshitish K; Chattopadhyay, P K; Ghosh, J; Kumar, Sunil; Saxena, Y C

2012-06-01

Current free double layers (CFDLs) are localized potential structures having spatial dimensions - Debye lengths and potential drops of more than local electron temperature across them. CFDLs do not need a current for them to be sustained and hence they differ from the current driven double layers. Helicon antenna produced plasmas in an expanded chamber along with an expanding magnetic field have shown the existence of CFDL near the expansion region. A helicon plasma device has been designed, fabricated, and installed in the Institute for Plasma Research, India to study the role of maximum magnetic field gradient as well as its location with respect to the geometrical expansion region of the chamber in CFDL formation. The special feature of this machine consisting of two chambers of different radii is its capability of producing different magnetic field gradients near the physical boundary between the two chambers either by changing current in one particular coil in the direction opposite to that in other coils and/or by varying the position of this particular coil. Although, the machine is primarily designed for CFDL experiments, it is also capable of carrying out many basic plasma physics experiments such as wave propagation, wave coupling, and plasma instabilities in a varying magnetic field topology. In this paper, we will present the details of the machine construction, its specialties, and some preliminary results about the production and characterization of helicon plasma in this machine.

Collisionless effects on beam-return current systems in solar flares

NASA Technical Reports Server (NTRS)

Vlahos, L.; Rowland, H. L.

1985-01-01

A theoretical study of the beam-return current system (BRCS) in solar flares shows that the precipitating electrons modify the way in which the return current (RC) is carried by the background plasma. In particular it is found that the RC is not carried by the bulk of the electrons but by a small number of high-velocity electrons. For beam/plasma densities exceeding approximately 0.001, this can reduce the effects of collisions and heating by the RC. For higher-density beams, where the RC could be unstable to current-driven instabilities, the effects of strong turbulence anomalous resistivity prevent the appearance of such instabilities. The main conclusion is that the BRCS is interconnected, and that the beam-generated strong turbulence determines how the RC is carried.

The Clinical Presentation of Oral Potentially Malignant Disorders.

PubMed

Mccormick, Neal J; Thomson, Peter J; Carrozzo, Marco

2016-02-01

Early detection of oral cancer improves survival rates significantly, however, the incidence of oral cancer has continued to rise in the UK - between 2002-2012, it increased by more than 30%. There is currently no national screening programme for oral cancer, so undertaking a full examination of the oral mucosa during routine dental appointments is vital. Although strong evidence is still lacking, oral cancer is thought to be preceded by oral potential malignant disorders (OPMDs) or oral precancerous diseases. These mainly present as white/red lesions within the mouth and their clinical appearance can be challenging to diagnose accurately, which can lead to them being misdiagnosed as negligible problems. Dentists must keep up to date with OPMDs detection and ensure they are capable of correctly recognising lesions that carry a potential risk. This paper aims to provide a brief overview on OPMDs, highlighting potentially malignant disorders as they may present to the practitioner, showing their typical clinical appearance, and suggesting differential diagnosis and clinical management in dental practice.

Influence of Chloride Ions as Contaminants on the Corrosion Behavior of Alloy 718 in Pool Water of Nuclear Power Plants

NASA Astrophysics Data System (ADS)

Hugues, Jonathan; Andrieu, Eric; Blanc, Christine; Cloué, Jean-Marc

The electrochemical behavior of alloy 718 in a chloride-containing boric acid solution was studied to determine the influence of chloride ions as contaminants of pool water of nuclear power plants on the corrosion behavior of the alloy. Experiments were performed at 20°C and 60°C with chloride concentrations from 1.5 to 15 000 ppm, using stationary measurements i.e. OCP versus time measurements and plotting of current-potential curves. After the electrochemical tests, the samples were observed using optical microscopy. Immersion tests in chloride-containing boric acid solutions were also carried out: samples were immersed for a time as long as 17 weeks at open circuit potential and their residual mechanical properties were measured. Results showed that, whatever the chloride concentration, there was no corrosion for samples immersed at open circuit potential. However, when the samples were polarized at high potentials, intergranular corrosion might be observed in occluded zones.

Magnetic Field Due to a Finite Length Current-Carrying Wire Using the Concept of Displacement Current

ERIC Educational Resources Information Center

Buschauer, Robert

2014-01-01

In undergraduate E&M courses the magnetic field due to a finite length, current-carrying wire can be calculated using the Biot-Savart law. However, to the author's knowledge, no textbook presents the calculation of this field using the Ampere-Maxwell law: ?B [multiplied by] dl = µ[subscript 0] (I + e[subscript 0] dF/dt) [multiplied by] 1

Studies of the System-Environment Interaction by Electron Beam Emission from a Sounding Rocket Payload in the Ionosphere

NASA Astrophysics Data System (ADS)

Myers, Neil Brubaker

The CHARGE-2 sounding rocket payload was designed to measure the transient and steady-state electrical charging of a space vehicle at low-Earth-orbit altitudes during the emission of a low-power electron beam from the vehicle. In addition to the electron gun, the payload contained several diagnostics to monitor plasma and waves resulting from the beam/space/vehicle interaction. The payload was separated into two sections, the larger section carried a 1-keV electron gun and was referred to as the mother vehicle. The smaller section, referred to as the daughter, was connected to the mother by an insulated, conducting tether and was deployed to a distance of up to 426 m across the geomagnetic field. Payload stabilization was obtained using thrusters that released cold nitrogen gas. In addition to performing electron beam experiments, the mother vehicle contained a high-voltage power supply capable of applying up to +450 V and 28 mA to the daughter through the tether. The 1-keV electron beam was generated at beam currents of 1 mA to 48 mA, measured at the exit aperture of the electron gun. Steady-state potentials of up to 560 V were measured for the mother vehicle. The daughter attained potentials of up to 1000 V relative to the background ionosphere and collected currents up to 6.5 mA. Thruster firings increased the current collection to the vehicle firing the thrusters and resulted in neutralization of the payload. The CHARGE-2 experiment was unique in that for the first time a comparison was made of the current collection between an electron beam-emitting vehicle and a non-emitting vehicle at high potential (400 V to 1000 V). The daughter current collection agreed well with the Parker-Murphy model, while the mother current collection always exceeded the Parker-Murphy limit and even exceeded the Langmuir-Blodgett predicted current below 240 km. The additional current collection of the mother is attributed to beam-plasma interaction. This additional source of collected current may be very important for successful electron beam emission at altitudes below 240 km.

Engraftment potential of dermal fibroblasts following in vivo myogenic conversion in immunocompetent dystrophic skeletal muscle

PubMed Central

Muir, Lindsey A; Nguyen, Quynh G; Hauschka, Stephen D; Chamberlain, Jeffrey S

2014-01-01

Autologous dermal fibroblasts (dFbs) are promising candidates for enhancing muscle regeneration in Duchenne muscular dystrophy (DMD) due to their ease of isolation, immunological compatibility, and greater proliferative potential than DMD satellite cells. We previously showed that mouse fibroblasts, after MyoD-mediated myogenic reprogramming in vivo, engraft in skeletal muscle and supply dystrophin. Assessing the therapeutic utility of this system requires optimization of conversion and transplantation conditions and quantitation of engraftment so that these parameters can be correlated with possible functional improvements. Here, we derived dFbs from transgenic mice carrying mini-dystrophin, transduced them by lentivirus carrying tamoxifen-inducible MyoD, and characterized their myogenic and engraftment potential. After cell transplantation into the muscles of immunocompetent dystrophic mdx4cv mice, tamoxifen treatment drove myogenic conversion and fusion into myofibers that expressed high levels of mini-dystrophin. Injecting 50,000 cells/µl (1 × 106 total cells) resulted in a peak of ~600 mini-dystrophin positive myofibers in tibialis anterior muscle single cross-sections. However, extensor digitorum longus muscles with up to 30% regional engraftment showed no functional improvements; similar limitations were obtained with whole muscle mononuclear cells. Despite the current lack of physiological improvement, this study suggests a viable initial strategy for using a patient-accessible dermal cell population to enhance skeletal muscle regeneration in DMD. PMID:25558461

Predatory fish depletion and recovery potential on Caribbean reefs.

PubMed

Valdivia, Abel; Cox, Courtney Ellen; Bruno, John Francis

2017-03-01

The natural, prehuman abundance of most large predators is unknown because of the lack of historical data and a limited understanding of the natural factors that control their populations. Determining the supportable predator biomass at a given location (that is, the predator carrying capacity) would help managers to optimize protection and would provide site-specific recovery goals. We assess the relationship between predatory reef fish biomass and several anthropogenic and environmental variables at 39 reefs across the Caribbean to (i) estimate their roles determining local predator biomass and (ii) determine site-specific recovery potential if fishing was eliminated. We show that predatory reef fish biomass tends to be higher in marine reserves but is strongly negatively related to human activities, especially coastal development. However, human activities and natural factors, including reef complexity and prey abundance, explain more than 50% of the spatial variation in predator biomass. Comparing site-specific predator carrying capacities to field observations, we infer that current predatory reef fish biomass is 60 to 90% lower than the potential supportable biomass in most sites, even within most marine reserves. We also found that the scope for recovery varies among reefs by at least an order of magnitude. This suggests that we could underestimate unfished biomass at sites that provide ideal conditions for predators or greatly overestimate that of seemingly predator-depleted sites that may have never supported large predator populations because of suboptimal environmental conditions.

Reducing Magnetic Fields Around Power Cables

NASA Technical Reports Server (NTRS)

Sargent, Noel B.; Gitelman, Florida; Pongracz-Bartha, Edward; Spalding, John

1993-01-01

Four power conductors arranged symmetrically about fifth grounded conductor. Four current-carrying wires arranged symmetrically around central grounded wire that nominally carries no current. In comparison with other cable configurations, this one results in smaller magnetic fields around cable. Technique for use when size of wires in cable makes twisting impractical.

Magnetospheric Reconnection in Modified Current-Sheet Equilibria

NASA Astrophysics Data System (ADS)

Newman, D. L.; Goldman, M. V.; Lapenta, G.; Markidis, S.

2012-10-01

Particle simulations of magnetic reconnection in Earth's magnetosphere are frequently initialized with a current-carrying Harris equilibrium superposed on a current-free uniform background plasma. The Harris equilibrium satisfies local charge neutrality, but requires that the sheet current be dominated by the hotter species -- often the ions in Earth's magnetosphere. This constraint is not necessarily consistent with observations. A modified kinetic equilibrium that relaxes this constraint on the currents was proposed by Yamada et al. [Phys. Plasmas., 7, 1781 (2000)] with no background population. These modified equilibria were characterized by an asymptotic converging or diverging electrostatic field normal to the current sheet. By reintroducing the background plasma, we have developed new families of equilibria where the asymptotic fields are suppressed by Debye shielding. Because the electrostatic potential profiles of these new equilibria contain wells and/or barriers capable of spatially isolating different populations of electrons and/or ions, these solutions can be further generalized to include classes of asymmetric kinetic equilibria. Examples of both symmetric and asymmetric equilibria will be presented. The dynamical evolution of these equilibria, when perturbed, will be further explored by means of implicit 2D PIC reconnection simulations, including comparisons with simulations employing standard Harris-equilibrium initializations.

Circular Array of Magnetic Sensors for Current Measurement: Analysis for Error Caused by Position of Conductor.

PubMed

Yu, Hao; Qian, Zheng; Liu, Huayi; Qu, Jiaqi

2018-02-14

This paper analyzes the measurement error, caused by the position of the current-carrying conductor, of a circular array of magnetic sensors for current measurement. The circular array of magnetic sensors is an effective approach for AC or DC non-contact measurement, as it is low-cost, light-weight, has a large linear range, wide bandwidth, and low noise. Especially, it has been claimed that such structure has excellent reduction ability for errors caused by the position of the current-carrying conductor, crosstalk current interference, shape of the conduction cross-section, and the Earth's magnetic field. However, the positions of the current-carrying conductor-including un-centeredness and un-perpendicularity-have not been analyzed in detail until now. In this paper, for the purpose of having minimum measurement error, a theoretical analysis has been proposed based on vector inner and exterior product. In the presented mathematical model of relative error, the un-center offset distance, the un-perpendicular angle, the radius of the circle, and the number of magnetic sensors are expressed in one equation. The comparison of the relative error caused by the position of the current-carrying conductor between four and eight sensors is conducted. Tunnel magnetoresistance (TMR) sensors are used in the experimental prototype to verify the mathematical model. The analysis results can be the reference to design the details of the circular array of magnetic sensors for current measurement in practical situations.

Integrating DNA barcode data and taxonomic practice: determination, discovery, and description.

PubMed

Goldstein, Paul Z; DeSalle, Rob

2011-02-01

DNA barcodes, like traditional sources of taxonomic information, are potentially powerful heuristics in the identification of described species but require mindful analytical interpretation. The role of DNA barcoding in generating hypotheses of new taxa in need of formal taxonomic treatment is discussed, and it is emphasized that the recursive process of character evaluation is both necessary and best served by understanding the empirical mechanics of the discovery process. These undertakings carry enormous ramifications not only for the translation of DNA sequence data into taxonomic information but also for our comprehension of the magnitude of species diversity and its disappearance. This paper examines the potential strengths and pitfalls of integrating DNA sequence data, specifically in the form of DNA barcodes as they are currently generated and analyzed, with taxonomic practice.

Survey of inorganic polymers. [for composite matrix resins

NASA Technical Reports Server (NTRS)

Gerber, A. H.; Mcinerney, E. F.

1979-01-01

A literature search was carried out in order to identify inorganic, metallo-organic, and hybrid inorganic-organic polymers that could serve as potential matrix resins for advanced composites. The five most promising candidates were critically reviewed and recommendations were made for the achievement of their potential in terms of performance and cost. These generic polymer classes comprise: (1) Poly(arylsil sesquioxanes); (2) Poly(silyl arylene siloxanes); (3) Poly(silarylenes); (4) Poly(silicon-linked ferrocenes); and (5) Poly(organo phosphazenes). No single candidate currently possesses the necessary combination of physicomechanical properties, thermal stability, processability, and favorable economics. The first three classes exhibit the best thermal performance. On the other hand, poly (organo phosphazenes), the most extensively studied polymer class, exhibit the best combination of structure-property control, processability, and favorable economics.

Using a full annual cycle model to evaluate long-term population viability of the conservation-reliant Kirtland's warbler after successful recovery

USGS Publications Warehouse

Brown, Donald J.; Ribic, Christine; Donner, Deahn M.; Nelson, Mark D.; Bocetti, Carol I.; Deloria-Sheffield, Christie M.

2017-01-01

Long-term management planning for conservation-reliant migratory songbirds is particularly challenging because habitat quality in different stages and geographic locations of the annual cycle can have direct and carry-over effects that influence the population dynamics. The Neotropical migratory songbird Kirtland's warbler Setophaga kirtlandii (Baird 1852) is listed as endangered under the U.S. Endangered Species Act and Near Threatened under the IUCN Red List. This conservation-reliant species is being considered for U.S. federal delisting because the species has surpassed the designated 1000 breeding pairs recovery threshold since 2001.To help inform the delisting decision and long-term management efforts, we developed a population simulation model for the Kirtland's warbler that incorporated both breeding and wintering grounds habitat dynamics, and projected population viability based on current environmental conditions and potential future management scenarios. Future management scenarios included the continuation of current management conditions, reduced productivity and carrying capacity due to the changes in habitat suitability from the creation of experimental jack pine Pinus banksiana (Lamb.) plantations, and reduced productivity from alteration of the brown-headed cowbird Molothrus ater (Boddaert 1783) removal programme.Linking wintering grounds precipitation to productivity improved the accuracy of the model for replicating past observed population dynamics. Our future simulations indicate that the Kirtland's warbler population is stable under two potential future management scenarios: (i) continuation of current management practices and (ii) spatially restricting cowbird removal to the core breeding area, assuming that cowbirds reduce productivity in the remaining patches by ≤41%. The additional future management scenarios we assessed resulted in population declines.Synthesis and applications. Our study indicates that the Kirtland's warbler population is stable under current management conditions and that the jack pine plantation and cowbird removal programmes continue to be necessary for the long-term persistence of the species. This study represents one of the first attempts to incorporate full annual cycle dynamics into a population viability analysis for a migratory bird, and our results indicate that incorporating wintering grounds dynamics improved the model performance.

A comprehensive study to evaluate the effect of constant low voltage iontophoresis on transungual delivery.

PubMed

Nair, Anroop B; Singh, Kishan; Shinu, Pottathil; Harsha, Sree; Al-Dhubiab, Bandar E

2013-05-01

Treatment of nail diseases by topical drug delivery continues to draw much attention in the recent days. This study aims to systematically investigate the effect of constant voltage iontophoresis in the transungual drug delivery, using ciclopirox as a model drug. Preliminary permeation studies were carried out by applying constant voltage (6 V for 24 h) using a gel formulation across the human nail plate in a Franz diffusion cell. Different protocols have been studied to authenticate the potential of the proposed technique. Antifungal studies were carried out to assess the pharmacodynamic effect of drug depot formed in the nail plate. Initial studies revealed that application of constant voltage iontophoresis enhanced the permeation by an order of magnitude (p = 0.019) and delivered significant amount of drug into the deeper nail layers. Noticeably higher permeation was observed during the active phase in on-off studies. Excellent correlation was observed in permeation (r(2) = 0.98) and drug load (r(2) = 0.97) with the increase in applied voltage (3-12 V), indicating that the current technique is predictable. The data observed suggest that any further increase in voltage could eventually lead to increase in the permeation and drug load, as the saturation level is very distant. Furthermore, the enhancement in permeation with the applied voltage (3-12 V) was found to be 6-20 folds, compared to the passive process. Results of step up and step down studies substantiated the viability of the current technique. Zone of inhibition measured during the antifungal studies demonstrated that the drug molecules loaded into the nail plate by low voltage iontophoresis is active and releases over an extended period of time (~32 days). Given the excellent results, the current technique could be used as an effective approach for the delivery of antimycotics, which would localize the drug at the infection site and potentially offer higher patient compliance.

Electrolytic synthesis of carbon nanotubes from carbon dioxide in molten salts and their characterization

NASA Astrophysics Data System (ADS)

Novoselova, I. A.; Oliinyk, N. F.; Volkov, S. V.; Konchits, A. A.; Yanchuk, I. B.; Yefanov, V. S.; Kolesnik, S. P.; Karpets, M. V.

2008-05-01

Carbon nanotubes (CNTs) were synthesized from CO 2 dissolved in molten salts using the novel electrolytic method developed by the authors. The electrolysis were carried out under current and potential controls. To establish the actual current and potential ranges, the electroreduction of carbon dioxide dissolved in the halide melts under an excess pressure up to 15 bar was studied by cyclic voltammetry on glassy-carbon (GC) electrode at a temperature of 550 °C. The electrochemical-chemical-electrochemical mechanism of CO 2 electroreduction was offered for explanation of the obtained results. The structure, morphology, and electronic properties of the CNTs obtained were studied using SEM, TEM, X-ray and electron diffraction analysis, Raman and ESR spectroscopy. It was found that the majority of the CNTs are multi-walled (MWCNTs), have curved form, and most often agglomerate into bundles. Almost all CNTs are filled partly with electrolyte salt. Except MWCNTs the cathode product contains carbon nanofibers, nanographite, and amorphous carbon. The dependences of CNT's yield, their diameter, and structure peculiarities against the electrolysis regimes were established.

The Eye As a Biomarker for Alzheimer's Disease

PubMed Central

Lim, Jeremiah K. H.; Li, Qiao-Xin; He, Zheng; Vingrys, Algis J.; Wong, Vickie H. Y.; Currier, Nicolas; Mullen, Jamie; Bui, Bang V.; Nguyen, Christine T. O.

2016-01-01

Alzheimer's disease (AD) is a progressive neurodegenerative disorder resulting in dementia and eventual death. It is the leading cause of dementia and the number of cases are projected to rise in the next few decades. Pathological hallmarks of AD include the presence of hyperphosphorylated tau and amyloid protein deposition. Currently, these pathological biomarkers are detected either through cerebrospinal fluid analysis, brain imaging or post-mortem. Though effective, these methods are not widely available due to issues such as the difficulty in acquiring samples, lack of infrastructure or high cost. Given that the eye possesses clear optics and shares many neural and vascular similarities to the brain, it offers a direct window to cerebral pathology. These unique characteristics lend itself to being a relatively inexpensive biomarker for AD which carries the potential for wide implementation. The development of ocular biomarkers can have far implications in the discovery of treatments which can improve the quality of lives of patients. In this review, we consider the current evidence for ocular biomarkers in AD and explore potential future avenues of research in this area. PMID:27909396

Frequency-selective augmenting responses by short-term synaptic depression in cat neocortex

PubMed Central

Houweling, Arthur R; Bazhenov, Maxim; Timofeev, Igor; Grenier, François; Steriade, Mircea; Sejnowski, Terrence J

2002-01-01

Thalamic stimulation at frequencies between 5 and 15 Hz elicits incremental or ‘augmenting’ cortical responses. Augmenting responses can also be evoked in cortical slices and isolated cortical slabs in vivo. Here we show that a realistic network model of cortical pyramidal cells and interneurones including short-term plasticity of inhibitory and excitatory synapses replicates the main features of augmenting responses as obtained in isolated slabs in vivo. Repetitive stimulation of synaptic inputs at frequencies around 10 Hz produced postsynaptic potentials that grew in size and carried an increasing number of action potentials resulting from the depression of inhibitory synaptic currents. Frequency selectivity was obtained through the relatively weak depression of inhibitory synapses at low frequencies, and strong depression of excitatory synapses together with activation of a calcium-activated potassium current at high frequencies. This network resonance is a consequence of short-term synaptic plasticity in a network of neurones without intrinsic resonances. These results suggest that short-term plasticity of cortical synapses could shape the dynamics of synchronized oscillations in the brain. PMID:12122156

Impact of Shale Gas Development on Water Resources: A Case Study in Northern Poland

NASA Astrophysics Data System (ADS)

Vandecasteele, Ine; Marí Rivero, Inés; Sala, Serenella; Baranzelli, Claudia; Barranco, Ricardo; Batelaan, Okke; Lavalle, Carlo

2015-06-01

Shale gas is currently being explored in Europe as an alternative energy source to conventional oil and gas. There is, however, increasing concern about the potential environmental impacts of shale gas extraction by hydraulic fracturing (fracking). In this study, we focussed on the potential impacts on regional water resources within the Baltic Basin in Poland, both in terms of quantity and quality. The future development of the shale play was modeled for the time period 2015-2030 using the LUISA modeling framework. We formulated two scenarios which took into account the large range in technology and resource requirements, as well as two additional scenarios based on the current legislation and the potential restrictions which could be put in place. According to these scenarios, between 0.03 and 0.86 % of the total water withdrawals for all sectors could be attributed to shale gas exploitation within the study area. A screening-level assessment of the potential impact of the chemicals commonly used in fracking was carried out and showed that due to their wide range of physicochemical properties, these chemicals may pose additional pressure on freshwater ecosystems. The legislation put in place also influenced the resulting environmental impacts of shale gas extraction. Especially important are the protection of vulnerable ground and surface water resources and the promotion of more water-efficient technologies.

Impact of shale gas development on water resources: a case study in northern poland.

PubMed

Vandecasteele, Ine; Marí Rivero, Inés; Sala, Serenella; Baranzelli, Claudia; Barranco, Ricardo; Batelaan, Okke; Lavalle, Carlo

2015-06-01

Shale gas is currently being explored in Europe as an alternative energy source to conventional oil and gas. There is, however, increasing concern about the potential environmental impacts of shale gas extraction by hydraulic fracturing (fracking). In this study, we focussed on the potential impacts on regional water resources within the Baltic Basin in Poland, both in terms of quantity and quality. The future development of the shale play was modeled for the time period 2015-2030 using the LUISA modeling framework. We formulated two scenarios which took into account the large range in technology and resource requirements, as well as two additional scenarios based on the current legislation and the potential restrictions which could be put in place. According to these scenarios, between 0.03 and 0.86% of the total water withdrawals for all sectors could be attributed to shale gas exploitation within the study area. A screening-level assessment of the potential impact of the chemicals commonly used in fracking was carried out and showed that due to their wide range of physicochemical properties, these chemicals may pose additional pressure on freshwater ecosystems. The legislation put in place also influenced the resulting environmental impacts of shale gas extraction. Especially important are the protection of vulnerable ground and surface water resources and the promotion of more water-efficient technologies.

Scanning tunneling microscopy measurements of the spin Hall effect in tungsten films by using iron-coated tungsten tips

NASA Astrophysics Data System (ADS)

Xie, Ting; Dreyer, Michael; Bowen, David; Hinkel, Dan; Butera, R. E.; Krafft, Charles; Mayergoyz, Isaak

2018-05-01

Scanning tunneling microscopy experiments using iron-coated tungsten tips and current-carrying tungsten films have been conducted. An asymmetry of the tunneling current with respect to the change of the direction of the bias current through a tungsten film has been observed. It is argued that this asymmetry is a manifestation of the spin Hall effect in the current-carrying tungsten film. Nanoscale variations of this asymmetry across the tungsten film have been studied by using the scanning tunneling microscopy technique.

Lorentz Contraction and Current-Carrying Wires

ERIC Educational Resources Information Center

van Kampen, Paul

2008-01-01

The force between two parallel current-carrying wires is investigated in the rest frames of the ions and the electrons. A straightforward Lorentz transformation shows that what appears as a purely magnetostatic force in the ion frame appears as a combined magnetostatic and electrostatic force in the electron frame. The derivation makes use of a…

Charged Particle Dynamics in the Magnetic Field of a Long Straight Current-Carrying Wire

ERIC Educational Resources Information Center

Prentice, A.; Fatuzzo, M.; Toepker, T.

2015-01-01

By describing the motion of a charged particle in the well-known nonuniform field of a current-carrying long straight wire, a variety of teaching/learning opportunities are described: 1) Brief review of a standard problem; 2) Vector analysis; 3) Dimensionless variables; 4) Coupled differential equations; 5) Numerical solutions.

One-Step Hydrothermal-Electrochemical Route to Carbon-Stabilized Anatase Powders

NASA Astrophysics Data System (ADS)

Tao, Ying; Yi, Danqing; Zhu, Baojun

2013-04-01

Black carbon-stabilized anatase particles were prepared by a simple one-step hydrothermal-electrochemical method using glucose and titanium citrate as the carbon and titanium source, respectively. Morphological, chemical, structural, and electrochemical characterizations of these powders were carried out by Raman spectroscopy, Fourier-transform infrared spectroscopy, x-ray diffraction, scanning electron microscopy, and cyclic voltammetry. It was revealed that 200-nm carbon/anatase TiO2 was homogeneously dispersed, and the powders exhibited excellent cyclic performance at high current rates of 0.05 V/s. The powders are interesting potential materials that could be used as anodes for lithium-ion batteries.

Kinetic and functional analysis of transient, persistent and resurgent sodium currents in rat cerebellar granule cells in situ: an electrophysiological and modelling study

PubMed Central

Magistretti, Jacopo; Castelli, Loretta; Forti, Lia; D'Angelo, Egidio

2006-01-01

Cerebellar neurones show complex and differentiated mechanisms of action potential generation that have been proposed to depend on peculiar properties of their voltage-dependent Na+ currents. In this study we analysed voltage-dependent Na+ currents of rat cerebellar granule cells (GCs) by performing whole-cell, patch-clamp experiments in acute rat cerebellar slices. A transient Na+ current (INaT) was always present and had the properties of a typical fast-activating/inactivating Na+ current. In addition to INaT, robust persistent (INaP) and resurgent (INaR) Na+ currents were observed. INaP peaked at ∼−40 mV, showed half-maximal activation at ∼−55 mV, and its maximal amplitude was about 1.5% of that of INaT. INaR was elicited by repolarizing pulses applied following step depolarizations able to activate/inactivate INaT, and showed voltage- and time-dependent activation and voltage-dependent decay kinetics. The conductance underlying INaR showed a bell-shaped voltage dependence, with peak at −35 mV. A significant correlation was found between GC INaR and INaT peak amplitudes; however, GCs expressing INaT of similar size showed marked variability in terms of INaR amplitude, and in a fraction of cells INaR was undetectable. INaT, INaP and INaR could be accounted for by a 13-state kinetic scheme comprising closed, open, inactivated and blocked states. Current-clamp experiments carried out to identify possible functional correlates of INaP and/or INaR revealed that in GCs single action potentials were followed by depolarizing afterpotentials (DAPs). In a majority of cells, DAPs showed properties consistent with INaR playing a role in their generation. Computer modelling showed that INaR promotes DAP generation and enhances high-frequency firing, whereas INaP boosts near-threshold firing activity. Our findings suggest that special properties of voltage-dependent Na+ currents provides GCs with mechanisms suitable for shaping activity patterns, with potentially important consequences for cerebellar information transfer and computation. PMID:16527854

Online professional networks for physicians: risk management.

PubMed

Hyman, Jon L; Luks, Howard J; Sechrest, Randale

2012-05-01

The rapidly developing array of online physician-only communities represents a potential extraordinary advance in the availability of educational and informational resources to physicians. These online communities provide physicians with a new range of controls over the information they process, but use of this social media technology carries some risk. The purpose of this review was to help physicians manage the risks of online professional networking and discuss the potential benefits that may come with such networks. This article explores the risks and benefits of physicians engaging in online professional networking with peers and provides suggestions on risk management. Through an Internet search and literature review, we scrutinized available case law, federal regulatory code, and guidelines of conduct from professional organizations and consultants. We reviewed the OrthoMind.com site as a case example because it is currently the only online social network exclusively for orthopaedic surgeons. Existing case law suggests potential liability for orthopaedic surgeons who engage with patients on openly accessible social network platforms. Current society guidelines in both the United States and Britain provide sensible rules that may mitigate such risks. However, the overall lack of a strong body of legal opinions, government regulations as well as practical experience for most surgeons limit the suitability of such platforms. Closed platforms that are restricted to validated orthopaedic surgeons may limit these downside risks and hence allow surgeons to collaborate with one another both as clinicians and practice owners. Educating surgeons about the pros and cons of participating in these networking platforms is helping them more astutely manage risks and optimize benefits. This evolving online environment of professional interaction is one of few precedents, but the application of risk management strategies that physicians use in daily practice carries over into the online community. This participation should foster ongoing dialogue as new guidelines emerge. This will allow today's orthopaedic surgeon to feel more comfortable with online professional networks and better understand how to make an informed decision regarding their proper use.

Applicability of risk-based management and the need for risk-based economic decision analysis at hazardous waste contaminated sites.

PubMed

Khadam, Ibrahim; Kaluarachchi, Jagath J

2003-07-01

Decision analysis in subsurface contamination management is generally carried out through a traditional engineering economic viewpoint. However, new advances in human health risk assessment, namely, the probabilistic risk assessment, and the growing awareness of the importance of soft data in the decision-making process, require decision analysis methodologies that are capable of accommodating non-technical and politically biased qualitative information. In this work, we discuss the major limitations of the currently practiced decision analysis framework, which evolves around the definition of risk and cost of risk, and its poor ability to communicate risk-related information. A demonstration using a numerical example was conducted to provide insight on these limitations of the current decision analysis framework. The results from this simple ground water contamination and remediation scenario were identical to those obtained from studies carried out on existing Superfund sites, which suggests serious flaws in the current risk management framework. In order to provide a perspective on how these limitations may be avoided in future formulation of the management framework, more matured and well-accepted approaches to decision analysis in dam safety and the utility industry, where public health and public investment are of great concern, are presented and their applicability in subsurface remediation management is discussed. Finally, in light of the success of the application of risk-based decision analysis in dam safety and the utility industry, potential options for decision analysis in subsurface contamination management are discussed.

Evaluation of the damages caused by lightning current flowing through bearings

NASA Technical Reports Server (NTRS)

Celi, O.; Pigini, A.; Garbagnati, E.

1991-01-01

A laboratory for lightning current tests was set up allowing the generation of the lightning currents foreseen by the Standards. Lightning tests are carried out on different objects, aircraft materials and components, evaluating the direct and indirect effects of lightning. Recently a research was carried out to evaluate the effects of the lightning current flow through bearings with special reference to wind power generator applications. For this purpose, lightning currents of different amplitude were applied to bearings in different test conditions and the damages caused by the lightning current flow were analyzed. The influence of the load acting on the bearing, the presence of lubricant and the bearing rotation were studied.

Numerical modelling of dynamic resistance in high-temperature superconducting coated-conductor wires

NASA Astrophysics Data System (ADS)

Ainslie, Mark D.; Bumby, Chris W.; Jiang, Zhenan; Toyomoto, Ryuki; Amemiya, Naoyuki

2018-07-01

The use of superconducting wire within AC power systems is complicated by the dissipative interactions that occur when a superconductor is exposed to an alternating current and/or magnetic field, giving rise to a superconducting AC loss caused by the motion of vortices within the superconducting material. When a superconductor is exposed to an alternating field whilst carrying a constant DC transport current, a DC electrical resistance can be observed, commonly referred to as ‘dynamic resistance.’ Dynamic resistance is relevant to many potential high-temperature superconducting (HTS) applications and has been identified as critical to understanding the operating mechanism of HTS flux pump devices. In this paper, a 2D numerical model based on the finite-element method and implementing the H -formulation is used to calculate the dynamic resistance and total AC loss in a coated-conductor HTS wire carrying an arbitrary DC transport current and exposed to background AC magnetic fields up to 100 mT. The measured angular dependence of the superconducting properties of the wire are used as input data, and the model is validated using experimental data for magnetic fields perpendicular to the plane of the wire, as well as at angles of 30° and 60° to this axis. The model is used to obtain insights into the characteristics of such dynamic resistance, including its relationship with the applied current and field, the wire’s superconducting properties, the threshold field above which dynamic resistance is generated and the flux-flow resistance that arises when the total driven transport current exceeds the field-dependent critical current, I c( B ), of the wire. It is shown that the dynamic resistance can be mostly determined by the perpendicular field component with subtle differences determined by the angular dependence of the superconducting properties of the wire. The dynamic resistance in parallel fields is essentially negligible until J c is exceeded and flux-flow resistance occurs.

Current trends in the use of vitamin E-based micellar nanocarriers for anticancer drug delivery.

PubMed

Muddineti, Omkara Swami; Ghosh, Balaram; Biswas, Swati

2017-06-01

Owing to the complexity of cancer pathogenesis, conventional chemotherapy can be an inadequate method of killing cancer cells effectively. Nanoparticle-based drug delivery systems have been widely exploited pre-clinically in recent years. Areas covered: Incorporation of vitamin-E in nanocarriers have the advantage of (1) improving the hydrophobicity of the drug delivery system, thereby improving the solubility of the loaded poorly soluble anticancer drugs, (2) enhancing the biocompatibility of the polymeric drug carriers, and (3) improving the anticancer potential of the chemotherapeutic agents by reversing the cellular drug resistance via simultaneous administration. In addition to being a powerful antioxidant, vitamin E demonstrated its anticancer potential by inducing apoptosis in various cancer cell lines. Various vitamin E analogs have proven their ability to cause marked inhibition of drug efflux transporters. Expert opinion: The review discusses the potential of incorporating vitamin E in the polymeric micelles which are designed to carry poorly water-soluble anticancer drugs. Current applications of various vitamin E-based polymeric micelles with emphasis on the use of α-tocopherol, D-α-tocopheryl succinate (α-TOS) and its conjugates such as D-α-tocopheryl polyethylene glycol-succinate (TPGS) in micellar system is delineated. Advantages of utilizing polymeric micelles for drug delivery and the challenges to treat cancer, including multiple drug resistance have been discussed.

Carbon Nanomaterials Interfacing with Neurons: An In vivo Perspective

PubMed Central

Baldrighi, Michele; Trusel, Massimo; Tonini, Raffaella; Giordani, Silvia

2016-01-01

Developing new tools that outperform current state of the art technologies for imaging, drug delivery or electrical sensing in neuronal tissues is one of the great challenges in neurosciences. Investigations into the potential use of carbon nanomaterials for such applications started about two decades ago. Since then, numerous in vitro studies have examined interactions between these nanomaterials and neurons, either by evaluating their compatibility, as vectors for drug delivery, or for their potential use in electric activity sensing and manipulation. The results obtained indicate that carbon nanomaterials may be suitable for medical therapies. However, a relatively small number of in vivo studies have been carried out to date. In order to facilitate the transformation of carbon nanomaterial into practical neurobiomedical applications, it is essential to identify and highlight in the existing literature the strengths and weakness that different carbon nanomaterials have displayed when probed in vivo. Unfortunately the current literature is sometimes sparse and confusing. To offer a clearer picture of the in vivo studies on carbon nanomaterials in the central nervous system, we provide a systematic and critical review. Hereby we identify properties and behavior of carbon nanomaterials in vivo inside the neural tissues, and we examine key achievements and potentially problematic toxicological issues. PMID:27375413

Liquid biopsies in gastrointestinal malignancies: when is the big day?

PubMed

Lopez, Anthony; Harada, Kazuto; Mizrak Kaya, Dilsa; Dong, Xiaochuan; Song, Shumei; Ajani, Jaffer A

2018-01-01

Tumor tissue sample is currently the gold standard for diagnosing gastrointestinal cancers, but also for genomic/immune component analyses that can help in the selection of therapy. However, this approach of studying a 'representative' sample of the tumor does not address inherent heterogeneity. Liquid biopsies, mainly represented by circulating tumor cells, circulating tumor DNA, tumor exosomes, and microRNAs, have the potential to assess various biomarkers for early detection of cancer, carrying out genomic/immune profiling for not only selection of appropriate therapy but also to monitor effect of therapy. Areas covered: This review summarizes the current evidence in the literature on liquid biopsies in gastrointestinal cancers concerning diagnosis, prognosis, and response to therapy. The following terms were used in PubMed: 'esophageal', 'gastric', 'colorectal', 'cancer', 'circulating tumor cells', 'circulating tumor DNA', microRNA', 'diagnosis', 'prognosis', 'response', 'resistance'. Expert commentary: Data increasingly supports the potential of liquid biopsies for early detection, selection of therapy, and monitoring response to therapy. One major question is whether assaying various components of the blood would accommodate considerable context-dependent heterogeneity of gastrointestinal tumors. There are many potential strategies to exploit liquid biopsy use. To put them in to perspective, well-designed and meticulous prospective studies will be needed to prove their usefulness.

MicroRNA as therapeutic targets for treatment of depression

PubMed Central

Hansen, Katelin F; Obrietan, Karl

2013-01-01

Depression is a potentially life-threatening mental disorder affecting approximately 300 million people worldwide. Despite much effort, the molecular underpinnings of clinical depression remain poorly defined, and current treatments carry limited therapeutic efficacy and potentially burdensome side effects. Recently, small noncoding RNA molecules known as microRNA (miRNA) have gained prominence as a target for therapeutic intervention, given their capacity to regulate neuronal physiology. Further, mounting evidence suggests a prominent role for miRNA in depressive molecular signaling. Recent studies have demonstrated that dysregulation of miRNA expression occurs in animal models of depression, and in the post-mortem tissue of clinically depressed patients. Investigations into depression-associated miRNA disruption reveals dramatic effects on downstream targets, many of which are thought to contribute to depressive symptoms. Furthermore, selective serotonin reuptake inhibitors, as well as other antidepressant drugs, have the capacity to reverse aberrant depressive miRNA expression and their downstream targets. Given the powerful effects that miRNA have on the central nervous system transcriptome, and the aforementioned studies, there is a compelling rationale to begin to assess the potential contribution of miRNA to depressive etiology. Here, we review the molecular biology of miRNA, our current understanding of miRNA in relation to clinical depression, and the utility of targeting miRNA for antidepressant treatment. PMID:23935365

Volcanic risk assessment: Quantifying physical vulnerability in the built environment

NASA Astrophysics Data System (ADS)

Jenkins, S. F.; Spence, R. J. S.; Fonseca, J. F. B. D.; Solidum, R. U.; Wilson, T. M.

2014-04-01

This paper presents structured and cost-effective methods for assessing the physical vulnerability of at-risk communities to the range of volcanic hazards, developed as part of the MIA-VITA project (2009-2012). An initial assessment of building and infrastructure vulnerability has been carried out for a set of broadly defined building types and infrastructure categories, with the likelihood of damage considered separately for projectile impact, ash fall loading, pyroclastic density current dynamic pressure and earthquake ground shaking intensities. In refining these estimates for two case study areas: Kanlaon volcano in the Philippines and Fogo volcano in Cape Verde, we have developed guidelines and methodologies for carrying out physical vulnerability assessments in the field. These include identifying primary building characteristics, such as construction material and method, as well as subsidiary characteristics, for example the size and prevalence of openings, that may be important in assessing eruption impacts. At-risk buildings around Kanlaon were found to be dominated by timber frame buildings that exhibit a high vulnerability to pyroclastic density currents, but a low vulnerability to failure from seismic shaking. Around Fogo, the predominance of unreinforced masonry buildings with reinforced concrete slab roofs suggests a high vulnerability to volcanic earthquake but a low vulnerability to ash fall loading. Given the importance of agriculture for local livelihoods around Kanlaon and Fogo, we discuss the potential impact of infrastructure vulnerability for local agricultural economies, with implications for volcanic areas worldwide. These methodologies and tools go some way towards offering a standardised approach to carrying out future vulnerability assessments for populated volcanic areas.

Rehabilitation strategies enhancing participation in shopping malls for persons living with a disability.

PubMed

Alary Gauvreau, Christine; Kairy, Dahlia; Mazer, Barbara; Guindon, Andréanne; Le Dorze, Guylaine

2018-04-01

After rehabilitation, it is not clear the extent to which persons living with a disability return to their former activities in the community, such as going to shopping malls. Rehabilitation professionals are faced with the challenge to adequately prepare their clients to resume community participation. The purpose of this study was to identify rehabilitation strategies aimed at preparing clients to engage in activities in shopping malls. Twenty-two participants including 16 rehabilitation clinicians and 6 persons living with a disability participated in four nominal group sessions. Participants were questioned on current or potential rehabilitation strategies carried out to enhance participation in shopping malls for persons living with a disability. Discussions were audio-recorded and qualitative content analysis was conducted. Participants mentioned strategies that were either carried out by the clinician, or in collaboration with other parties. The latter type of strategies was either carried out with the collaboration of the client, the interdisciplinary team, the relatives, or community organizations. Rehabilitation clinicians have a role to play in preparing persons living with a disability to resume activities in a shopping mall. Additionally, therapeutic interventions in community settings may enhance the participation of rehabilitation clients in their everyday activities. Implications for rehabilitation Many strategies are currently used in rehabilitation to prepare persons living with a disability to resume shopping activities. Clinicians could implement shopping-oriented rehabilitation strategies with the client and/or with other rehabilitation partners. Involving clients in activities related to shopping might enhance their participation in shopping malls after rehabilitation. Rehabilitation clinicians can be facilitators for people living with a disability to reach optimal participation.

The Electrical Double Layer and Its Structure

NASA Astrophysics Data System (ADS)

Stojek, Zbigniew

At any electrode immersed in an electrolyte solution, a specific interfacial region is formed. This region is called the double layer. The electrical properties of such a layer are important, since they significantly affect the electrochemical measurements. In an electrical circuit used to measure the current that flows at a particular working electrode, the double layer can be viewed as a capacitor. Figure I.1.1 depicts this situation where the electrochemical cell is represented by an electrical circuit and capacitor C d corresponds to the differential capacity of the double layer. To obtain a desired potential at the working electrodes, the double-layer capacitor must be first appropriately charged, which means that a capacitive current, not related to the reduction or oxidation of the substrates, flows in the electrical circuit. While this capacitive current carries some information concerning the double layer and its structure, and in some cases can be used for analytical purposes, in general, it interferes with electrochemical investigations. A variety of methods are used in electrochemistry to depress, isolate, or filter the capacitive current.

Streaming current magnetic fields in a charged nanopore

PubMed Central

Mansouri, Abraham; Taheri, Peyman; Kostiuk, Larry W.

2016-01-01

Magnetic fields induced by currents created in pressure driven flows inside a solid-state charged nanopore were modeled by numerically solving a system of steady state continuum partial differential equations, i.e., Poisson, Nernst-Planck, Ampere and Navier-Stokes equations (PNPANS). This analysis was based on non-dimensional transport governing equations that were scaled using Debye length as the characteristic length scale, and applied to a finite length cylindrical nano-channel. The comparison of numerical and analytical studies shows an excellent agreement and verified the magnetic fields density both inside and outside the nanopore. The radially non-uniform currents resulted in highly non-uniform magnetic fields within the nanopore that decay as 1/r outside the nanopore. It is worth noting that for either streaming currents or streaming potential cases, the maximum magnetic field occurred inside the pore in the vicinity of nanopore wall, as opposed to a cylindrical conductor that carries a steady electric current where the maximum magnetic fields occur at the perimeter of conductor. Based on these results, it is suggested and envisaged that non-invasive external magnetic fields readouts generated by streaming/ionic currents may be viewed as secondary electronic signatures of biomolecules to complement and enhance current DNA nanopore sequencing techniques. PMID:27833119

Investigation of cables for ionization chambers.

PubMed

Spokas, J J; Meeker, R D

1980-01-01

Seven coaxial cables which are in use for carrying currents generated in ionization chambers have been critically studied with reference to their suitability to this application. Included in this study are four low-noise triaxial cables and three low-noise two-conductor cables. For each cable the following characteristics were considered: inherent noise currents, currents produced by cable movements, polarization currents, the degree of electrostatic shielding of the central signal-carrying conductor, and radiation-induced cable currents. The study indicated that of the seven cables, two low-noise triaxial cables, both employing solid Teflon dielectric surrounding the central conductor, appear to offer the best overall performance for use with ionization chambers.

Science at the policy interface: volcano-monitoring technologies and volcanic hazard management

NASA Astrophysics Data System (ADS)

Donovan, Amy; Oppenheimer, Clive; Bravo, Michael

2012-07-01

This paper discusses results from a survey of volcanologists carried out on the Volcano Listserv during late 2008 and early 2009. In particular, it examines the status of volcano monitoring technologies and their relative perceived value at persistently and potentially active volcanoes. It also examines the role of different types of knowledge in hazard assessment on active volcanoes, as reported by scientists engaged in this area, and interviewees with experience from the current eruption on Montserrat. Conclusions are drawn about the current state of monitoring and the likely future research directions, and also about the roles of expertise and experience in risk assessment on active volcanoes; while local knowledge is important, it must be balanced with fresh ideas and expertise in a combination of disciplines to produce an advisory context that is conducive to high-level scientific discussion.

Atom chips in the real world: the effects of wire corrugation

NASA Astrophysics Data System (ADS)

Schumm, T.; Estève, J.; Figl, C.; Trebbia, J.-B.; Aussibal, C.; Nguyen, H.; Mailly, D.; Bouchoule, I.; Westbrook, C. I.; Aspect, A.

2005-02-01

We present a detailed model describing the effects of wire corrugation on the trapping potential experienced by a cloud of atoms above a current carrying micro wire. We calculate the distortion of the current distribution due to corrugation and then derive the corresponding roughness in the magnetic field above the wire. Scaling laws are derived for the roughness as a function of height above a ribbon shaped wire. We also present experimental data on micro wire traps using cold atoms which complement some previously published measurements [CITE] and which demonstrate that wire corrugation can satisfactorily explain our observations of atom cloud fragmentation above electroplated gold wires. Finally, we present measurements of the corrugation of new wires fabricated by electron beam lithography and evaporation of gold. These wires appear to be substantially smoother than electroplated wires.

Engineering cyanobacteria for fuels and chemicals production.

PubMed

Zhou, Jie; Li, Yin

2010-03-01

The world's energy and global warming crises call for sustainable, renewable, carbon-neutral alternatives to replace fossil fuel resources. Currently, most biofuels are produced from agricultural crops and residues, which lead to concerns about food security and land shortage. Compared to the current biofuel production system, cyanobacteria, as autotrophic prokaryotes, do not require arable land and can grow to high densities by efficiently using solar energy, CO(2), water, and inorganic nutrients. Moreover, powerful genetic techniques of cyanobacteria have been developed. For these reasons, cyanobacteria, which carry out oxygenic photosynthesis, are attractive hosts for production of fuels and chemicals. Recently, several chemicals including ethanol, isobutanol and isoprene have been produced by engineered cyanobacteria directly using solar energy, CO(2), and water. Cyanobacterium is therefore a potential novel cell factory for fuels and chemicals production to address global energy security and climate change issues.

Geomagnetically induced currents: Science, engineering, and applications readiness

NASA Astrophysics Data System (ADS)

Pulkkinen, A.; Bernabeu, E.; Thomson, A.; Viljanen, A.; Pirjola, R.; Boteler, D.; Eichner, J.; Cilliers, P. J.; Welling, D.; Savani, N. P.; Weigel, R. S.; Love, J. J.; Balch, C.; Ngwira, C. M.; Crowley, G.; Schultz, A.; Kataoka, R.; Anderson, B.; Fugate, D.; Simpson, J. J.; MacAlester, M.

2017-07-01

This paper is the primary deliverable of the very first NASA Living With a Star Institute Working Group, Geomagnetically Induced Currents (GIC) Working Group. The paper provides a broad overview of the current status and future challenges pertaining to the science, engineering, and applications of the GIC problem. Science is understood here as the basic space and Earth sciences research that allows improved understanding and physics-based modeling of the physical processes behind GIC. Engineering, in turn, is understood here as the "impact" aspect of GIC. Applications are understood as the models, tools, and activities that can provide actionable information to entities such as power systems operators for mitigating the effects of GIC and government agencies for managing any potential consequences from GIC impact to critical infrastructure. Applications can be considered the ultimate goal of our GIC work. In assessing the status of the field, we quantify the readiness of various applications in the mitigation context. We use the Applications Readiness Level (ARL) concept to carry out the quantification.

Geomagnetically induced currents: Science, engineering, and applications readiness

USGS Publications Warehouse

Pulkkinen, Antti; Bernabeu, E.; Thomson, A.; Viljanen, A.; Pirjola, R.; Boteler, D.; Eichner, J.; Cilliers, P.J.; Welling, D.; Savani, N.P.; Weigel, R.S.; Love, Jeffrey J.; Balch, Christopher; Ngwira, C.M.; Crowley, G.; Schultz, Adam; Kataoka, R.; Anderson, B.; Fugate, D.; Simpson, J.J.; MacAlester, M.

2017-01-01

This paper is the primary deliverable of the very first NASA Living With a Star Institute Working Group, Geomagnetically Induced Currents (GIC) Working Group. The paper provides a broad overview of the current status and future challenges pertaining to the science, engineering, and applications of the GIC problem. Science is understood here as the basic space and Earth sciences research that allows improved understanding and physics-based modeling of the physical processes behind GIC. Engineering, in turn, is understood here as the “impact” aspect of GIC. Applications are understood as the models, tools, and activities that can provide actionable information to entities such as power systems operators for mitigating the effects of GIC and government agencies for managing any potential consequences from GIC impact to critical infrastructure. Applications can be considered the ultimate goal of our GIC work. In assessing the status of the field, we quantify the readiness of various applications in the mitigation context. We use the Applications Readiness Level (ARL) concept to carry out the quantification.

Neonatal Cranial Ultrasound: Are Current Safety Guidelines Appropriate?

PubMed

Lalzad, Assema; Wong, Flora; Schneider, Michal

2017-03-01

Ultrasound can lead to thermal and mechanical effects in interrogated tissues. We reviewed the literature to explore the evidence on ultrasound heating on fetal and neonatal neural tissue. The results of animal studies have suggested that ultrasound exposure of the fetal or neonatal brain may lead to a significant temperature elevation at the bone-brain interface above current recommended safety thresholds. Temperature increases between 4.3 and 5.6°C have been recorded. Such temperature elevations can potentially affect neuronal structure and function and may also affect behavioral and cognitive function, such as memory and learning. However, the majority of these studies were carried out more than 25 y ago using non-diagnostic equipment with power outputs much lower than those of modern machines. New studies to address the safety issues of cranial ultrasound are imperative to provide current clinical guidelines and safety recommendations. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Magnetless magnetic fusion

NASA Astrophysics Data System (ADS)

Beklemishev, A. D.; Tajima, T.

1994-02-01

The authors propose a concept of thermonuclear fusion reactor in which the plasma pressure is balanced by direct gas-wall interaction in a high-pressure vessel. The energy confinement is achieved by means of the self-contained toroidal magnetic configuration sustained by an external current drive or charged fusion products. This field structure causes the plasma pressure to decrease toward the inside of the discharge and thus it should be magnetohydrodynamically stable. The maximum size, temperature and density profiles of the reactor are estimated. An important feature of confinement physics is the thin layer of cold gas at the wall and the adjacent transitional region of dense arc-like plasma. The burning condition is determined by the balance between these nonmagnetized layers and the current-carrying plasma. They suggest several questions for future investigation, such as the thermal stability of the transition layer and the possibility of an effective heating and current drive behind the dense edge plasma. The main advantage of this scheme is the absence of strong external magnets and, consequently, potentially cheaper design and lower energy consumption.

Large pinning forces and matching effects in YBa2Cu3O7-δ thin films with Ba2Y(Nb/Ta)O6 nano-precipitates

NASA Astrophysics Data System (ADS)

Opherden, Lars; Sieger, Max; Pahlke, Patrick; Hühne, Ruben; Schultz, Ludwig; Meledin, Alexander; van Tendeloo, Gustaaf; Nast, Rainer; Holzapfel, Bernhard; Bianchetti, Marco; MacManus-Driscoll, Judith L.; Hänisch, Jens

2016-02-01

The addition of mixed double perovskite Ba2Y(Nb/Ta)O6 (BYNTO) to YBa2Cu3O7-δ (YBCO) thin films leads to a large improvement of the in-field current carrying capability. For low deposition rates, BYNTO grows as well-oriented, densely distributed nanocolumns. We achieved a pinning force density of 25 GN/m3 at 77 K at a matching field of 2.3 T, which is among the highest values reported for YBCO. The anisotropy of the critical current density shows a complex behavior whereby additional maxima are developed at field dependent angles. This is caused by a matching effect of the magnetic fields c-axis component. The exponent N of the current-voltage characteristics (inversely proportional to the creep rate S) allows the depinning mechanism to be determined. It changes from a double-kink excitation below the matching field to pinning-potential-determined creep above it.

Clinical perspective of cell-free DNA testing for fetal aneuploidies.

PubMed

Gratacós, Eduard; Nicolaides, Kypros

2014-01-01

Cell-free DNA testing in maternal blood provides the most effective method of screening for trisomy 21, with a reported detection rate of 99% and a false positive rate of less than 0.1%. After many years of research, this method is now commercially available and is carried out in an increasing number of patients, and there is an expanding number of conditions that can be screened for. However, the application of these methods in clinical practice requires a careful analysis. Current first-trimester screening strategies are based on a complex combination of tests, aiming at detecting fetal defects and predicting the risk of main pregnancy complications. It is therefore necessary to define the optimal way of combining cell-free DNA testing with current first-trimester screening methods. In this concise review we describe the basis of cell-free DNA testing and discuss the potential approaches for its implementation in combination with current tests in the first trimester. © 2014 S. Karger AG, Basel.

Sharp burnout failure observed in high current-carrying double-walled carbon nanotube fibers

NASA Astrophysics Data System (ADS)

Song, Li; Toth, Geza; Wei, Jinquan; Liu, Zheng; Gao, Wei; Ci, Lijie; Vajtai, Robert; Endo, Morinobu; Ajayan, Pulickel M.

2012-01-01

We report on the current-carrying capability and the high-current-induced thermal burnout failure modes of 5-20 µm diameter double-walled carbon nanotube (DWNT) fibers made by an improved dry-spinning method. It is found that the electrical conductivity and maximum current-carrying capability for these DWNT fibers can reach up to 5.9 × 105 S m - 1 and over 1 × 105 A cm - 2 in air. In comparison, we observed that standard carbon fiber tended to be oxidized and burnt out into cheese-like morphology when the maximum current was reached, while DWNT fiber showed a much slower breakdown behavior due to the gradual burnout in individual nanotubes. The electron microscopy observations further confirmed that the failure process of DWNT fibers occurs at localized positions, and while the individual nanotubes burn they also get aligned due to local high temperature and electrostatic field. In addition a finite element model was constructed to gain better understanding of the failure behavior of DWNT fibers.

Fundamentals of Physics, Part 3 (Chapters 22-33)

NASA Astrophysics Data System (ADS)

Halliday, David; Resnick, Robert; Walker, Jearl

2004-03-01

Chapter 21. Electric Charge. Why do video monitors in surgical rooms increase the risk of bacterial contamination? 21-1 What Is Physics? 21-2 Electric Charge. 21-3 Conductors and Insulators. 21-4 Coulomb's Law. 21-5 Charge Is Quantized. 21-6 Charge Is Conserved. Review & Summary. Questions. Problems. Chapter 22. Electric Fields. What causes sprites, those brief .ashes of light high above lightning storms? 22-1 What Is Physics? 22-2 The Electric Field. 22-3 Electric Field Lines. 22-4 The Electric Field Due to a Point Charge. 22-5 The Electric Field Due to an Electric Dipole. 22-6 The Electric Field Due to a Line of Charge. 22-7 The Electric Field Due to a Charged Disk. 22-8 A Point Charge in an Electric Field. 22-9 A Dipole in an Electric Field. Review & Summary. Questions. Problems. Chapter 23. Gauss' Law. How can lightning harm you even if it do es not strike you? 23-1 What Is Physics? 23-2 Flux. 23-3 Flux of an Electric Field. 23-4 Gauss' Law. 23-5 Gauss' Law and Coulomb's Law. 23-6 A Charged Isolated Conductor. 23-7 Applying Gauss' Law: Cylindrical Symmetry. 23-8 Applying Gauss' Law: Planar Symmetry. 23-9 Applying Gauss' Law: Spherical Symmetry. Review & Summary. Questions. Problems. Chapter 24. Electric Potential. What danger does a sweater pose to a computer? 24-1 What Is Physics? 24-2 Electric Potential Energy. 24-3 Electric Potential. 24-4 Equipotential Surfaces. 24-5 Calculating the Potential from the Field. 24-6 Potential Due to a Point Charge. 24-7 Potential Due to a Group of Point Charges. 24-8 Potential Due to an Electric Dipole. 24-9 Potential Due to a Continuous Charge Distribution. 24-10 Calculating the Field from the Potential. 24-11 Electric Potential Energy of a System of Point Charges. 24-12 Potential of a Charged Isolated Conductor. Review & Summary. Questions. Problems. Chapter 25. Capacitance. How did a fire start in a stretcher being withdrawn from an oxygen chamber? 25-1 What Is Physics? 25-2 Capacitance. 25-3 Calculating the Capacitance. 25-4 Capacitors in Parallel and in Series. 25-5 Energy Stored in an Electric Field. 25-6 Capacitor with a Dielectric. 25-7 Dielectrics: An Atomic View. 25-8 Dielectrics and Gauss' Law. Review & Summary. Questions. Problems. Chapter 26. Current and Resistance. What precaution should you take if caught outdoors during a lightning storm? 26-1 What Is Physics? 26-2 Electric Current. 26-3 Current Density. 26-4 Resistance and Resistivity. 26-5 Ohm's Law. 26-6 A Microscopic View of Ohm's Law. 26-7 Power in Electric Circuits. 26-8 Semiconductors. 26-9 Superconductors. Review & Summary. Questions. Problems. Chapter 27. Circuits. How can a pit crew avoid a fire while fueling a charged race car? 27-1 What Is Physics? 27-2 "Pumping" Charges. 27-3 Work, Energy, and Emf. 27-4 Calculating the Current in a Single-Loop Circuit. 27-5 Other Single-Loop Circuits. 27-6 Potential Difference Between Two Points. 27-7 Multiloop Circuits. 27-8 The Ammeter and the Voltmeter. 27-9 RC Circuits. Review & Summary. Questions. Problems. Chapter 28. Magnetic Fields. How can a beam of fast neutrons, which are electrically neutral, be produced in a hospital to treat cancer patients? 28-1 What Is Physics? 28-2 What Produces a Magnetic Field? 28-3 The Definition of 736 :B. 28-4 Crossed Fields: Discovery of the Electron . 28-5 Crossed Fields: The Hall Effect. 28-6 A Circulating Charged Particle. 28-7 Cyclotrons and Synchrotrons. 28-8 Magnetic Force on a Current-Carrying Wire. 28-9 Torque on a Current Loop. 28-10 The Magnetic Dipole Moment. Review & Summary. Questions. Problems. Chapter 29. Magnetic Fields Due to Currents. How can the human brain produce a detectable magnetic field without any magnetic material? 29-1 What Is Physics? 29-2 Calculating the Magnetic Field Due to a Current. 29-3 Force Between Two Parallel Currents. 29-4 Ampere's Law. 29-5 Solenoids and Toroids. 29-6 A Current-Carrying Coil as a Magnetic Dipole. Review & Summary. Questions. Problems. Chapter 30. Induction and Inductance. How can the magnetic .eld used in an MRI scan cause a patient to be burned? 30-1 What Is Physics? 30-2 Two Experiments. 30-3 Faraday's Law of Induction. 30-4 Lenz's Law. 30-5 Induction and Energy Transfers. 30-6 Induced Electric Fields. 30-7 Inductors and Inductance. 30-8 Self-Induction. 30-9 RL Circuits. 30-10 Energy Stored in a Magnetic Field. 30-11 Energy Density of a Magnetic Field. 30-12 Mutual Induction. Review & Summary. Questions. Problems. Chapter 31. Electromagnetic Oscillations and Alternating Current. How did a solar eruption knock out the power-grid system of Quebec? 31-1 What Is Physics? 31-2 LC Oscillations, Qualitatively. 31-3 The Electrical-Mechanical Analogy. 31-4 LC Oscillations, Quantitatively. 31-5 Damped Oscillations in an RLC Circuit. 31-6 Alternating Current. 31-7 Forced Oscillations. 31-8 Three Simple Circuits. 31-9 The Series RLC Circuit. 31-10 Power in Alternating-Current Circuits. 31-11 Transformers. Review & Summary. Questions. Problems. Chapter 32. Maxwell's Equations; Magnetism of Matter. How can a mural painting record the direction of Earth's magnetic field? 32-1 What Is Physics? 32-2 Gauss' Law for Magnetic Fields. 32-3 Induced Magnetic Fields. 32-4 Displacement Current. 32-5 Maxwell's Equations. 32-6 Magnets. 32-7 Magnetism and Electrons. 32-8 Magnetic Materials. 32-9 Diamagnetism. 32-10 Paramagnetism. 32-11 Ferromagnetism. Review & Summary. Questions. Problems. Appendices. A. The International System of Units (SI). B. Some Fundamental Constants of Physics. C. Some Astronomical Data. D. Conversion Factors. E. Mathematical Formulas. F. Properties of the Elements. G. Periodic Table of the Elements. Answers to Checkpoints and Odd-Numbered Questions and Problems. Index.

A Measurement of the Force between Two Current-Carrying Wires

ERIC Educational Resources Information Center

Straulino, S.; Cartacci, A.

2014-01-01

The measurement of the force acting between two parallel, current-carrying wires is known as Ampère's experiment. A mechanical balance was historically employed to measure that force. We report a simple experiment based on an electronic precision balance that is useful in clearly showing students the existence of this interaction and how to…

Charges and Fields in a Current-Carrying Wire

ERIC Educational Resources Information Center

Redzic, Dragan V.

2012-01-01

Charges and fields in a straight, infinite, cylindrical wire carrying a steady current are determined in the rest frames of ions and electrons, starting from the standard assumption that the net charge per unit length is zero in the lattice frame and taking into account a self-induced pinch effect. The analysis presented illustrates the mutual…

Human System Simulation in Support of Human Performance Technical Basis at NPPs

DOE Office of Scientific and Technical Information (OSTI.GOV)

David Gertman; Katya Le Blanc; alan mecham

2010-06-01

This paper focuses on strategies and progress toward establishing the Idaho National Laboratory’s (INL’s) Human Systems Simulator Laboratory at the Center for Advanced Energy Studies (CAES), a consortium of Idaho State Universities. The INL is one of the National Laboratories of the US Department of Energy. One of the first planned applications for the Human Systems Simulator Laboratory is implementation of a dynamic nuclear power plant simulation (NPP) where studies of operator workload, situation awareness, performance and preference will be carried out in simulated control rooms including nuclear power plant control rooms. Simulation offers a means by which to reviewmore » operational concepts, improve design practices and provide a technical basis for licensing decisions. In preparation for the next generation power plant and current government and industry efforts in support of light water reactor sustainability, human operators will be attached to a suite of physiological measurement instruments and, in combination with traditional Human Factors Measurement techniques, carry out control room tasks in simulated advanced digital and hybrid analog/digital control rooms. The current focus of the Human Systems Simulator Laboratory is building core competence in quantitative and qualitative measurements of situation awareness and workload. Of particular interest is whether introduction of digital systems including automated procedures has the potential to reduce workload and enhance safety while improving situation awareness or whether workload is merely shifted and situation awareness is modified in yet to be determined ways. Data analysis is carried out by engineers and scientists and includes measures of the physical and neurological correlates of human performance. The current approach supports a user-centered design philosophy (see ISO 13407 “Human Centered Design Process for Interactive Systems, 1999) wherein the context for task performance along with the requirements of the end-user are taken into account during the design process and the validity of design is determined through testing of real end users« less

Differential regulation of ASICs and TRPV1 by zinc in rat bronchopulmonary sensory neurons.

PubMed

Vysotskaya, Zhanna V; Moss, Charles R; Gu, Qihai

2014-12-01

Zinc has been known to act as a signaling molecule that regulates a variety of neuronal functions. In this study, we aimed to study the effect of zinc on two populations of acid-sensitive ion channels, acid-sensing ion channels (ASICs), and transient receptor potential vanilloid receptor-1 (TRPV1), in vagal bronchopulmonary sensory neurons. Rat vagal sensory neurons innervating lungs and airways were retrogradely labeled with a fluorescent tracer. Whole-cell perforated patch-clamp recordings were carried out in primarily cultured bronchopulmonary sensory neurons. The acid-evoked ASIC and TRPV1 currents were measured and compared between before and after the zinc pretreatment. ASIC currents were induced by a pH drop from 7.4 to 6.8 or 6.5 in the presence of capsazepine (10 µM), a specific TRPV1 antagonist. Pretreatment with zinc (50 or 300 µM, 2 min) displayed different effects on the two distinct phenotypes of ASIC currents: a marked potentiation on ASIC channels with fast kinetics of activation and inactivation or no significant effect on ASIC currents with slow activation and inactivation. On the other hand, pretreatment with zinc significantly inhibited the acid (pH 5.5 or 5.3)-induced TRPV1 currents. The inhibition was abolished by intracellular chelation of zinc by TPEN (25 µM), indicating that intracellular accumulation of zinc was likely required for its inhibitory effect on TRPV1 channels. Our study showed that zinc differentially regulates the activities of ASICs and TRPV1 channels in rat vagal bronchopulmonary sensory neurons.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foltyn, Stephen R; Jia, Quanxi; Arendt, Paul N

A superconducting tape having reduced AC losses. The tape has a high temperature superconductor layer that is segmented. Disruptive strips, formed in one of the tape substrate, a buffer layer, and the superconducting layer create parallel discontinuities in the superconducting layer that separate the current-carrying elements of the superconducting layer into strips or filament-like structures. Segmentation of the current-carrying elements has the effect of reducing AC current losses. Methods of making such a superconducting tape and reducing AC losses in such tapes are also disclosed.

Sleeping sickness in Uganda: revisiting current and historical distributions.

PubMed

Berrang-Ford, Lea; Odiit, Martin; Maiso, Faustin; Waltner-Toews, David; McDermott, John

2006-12-01

Sleeping sickness is a parasitic, vector-borne disease, carried by the tsetse fly and prevalent in sub-Saharan Africa. The disease continues to pose a public health burden in Uganda, which experienced a widespread outbreak in 1900-1920, and a more recent outbreak in 1976-1989. The disease continues to spread to uninfected districts. This paper compares the spatial distributions of sleeping in Uganda for the 1900-1920 outbreak period with current disease foci, and discusses information gaps and implications arising for future research, prevention and control. Population census records for 1911 and sleeping sickness records from Medical and Sanitary Reports of the Ugandan Protectorate for 1905-1936 were extracted from the Uganda Archives. Current sleeping sickness distribution data were provided by the Ministry of Health, Uganda. These were used to develop sleeping sickness distribution maps for comparison between the early 1900s and the early 2000s. The distribution of sleeping sickness from 1905-1920 shows notable differences compared to the current distribution of disease. In particular, archival cases were recorded in south-west and central Uganda, areas currently free of disease. The disease focus has moved from lakeshore Buganda (1905-1920) to the Busoga and south-east districts. Archival sleeping sickness distributions indicate the potential for a much wider area of disease risk than indicated by current disease foci. This is compounded by an absence of tsetse distribution data, continued political instability in north-central Uganda, continued spread of disease into new districts, and evidence of the role of livestock movements in spreading the parasite. These results support concerns as to the potential mergence of the two disease foci in the south-east and north-west of the country.

Cellular and synaptic effect of substance P on neonatal phrenic motoneurons.

PubMed

Ptak, K; Konrad, M; Di Pasquale, E; Tell, F; Hilaire, G; Monteau, R

2000-01-01

Experiments were carried out on the in vitro brainstem-spinal cord preparation of the newborn rat to analyse the effects of substance P (SP) on phrenic motoneuron (PMN) activity. In current-clamp mode, SP significantly depolarized PMNs, increased their input resistance, decreased the rheobase current and shifted the firing frequency-intensity relationships leftwards, but did not affect spike frequency adaptation or single spike configuration. The neurokinin receptor agonist NK1 had SP-mimetic effects, whereas the NK3 and NK2 receptor agonists were less effective and ineffective, respectively. In a tetrodotoxin-containing aCSF, only SP or the NK1 receptor agonist were still active. No depolarization was observed when the NK1 receptor agonist was applied in the presence of muscarine. In voltage-clamp mode, SP or the NK1 receptor agonist produced an inward current (ISP) which was not significantly reduced by extracellular application of tetraethylammonium, Co2+, 4-aminopyridine or Cs+. In aCSF containing tetrodotoxin, Co2+ and Cs+, ISP was blocked by muscarine. No PMN displayed any M-type potassium current but only a current showing no voltage sensitivity over the range -100 to 0 mV, reversing near the expected EK +, hence consistent with a leak current. SP application to the spinal cord only (using a partitioned chamber) significantly increased the phrenic activity. Pretreatment with the NMDA receptor antagonist DL-2-amino-5-phosphonovaleric acid (AP5) decreased the C4 discharge duration and blocked the effect of SP, thus exhibiting an NMDA potentiation by SP. In conclusion, SP modulates postsynaptically the response of phrenic motoneurons to the inspiratory drive through the reduction of a leak conductance and the potentiation of the NMDA component of the synaptic input.

Sensitization of transient receptor potential vanilloid 1 by the prokineticin receptor agonist Bv8.

PubMed

Vellani, Vittorio; Colucci, Mariantonella; Lattanzi, Roberta; Giannini, Elisa; Negri, Lucia; Melchiorri, Pietro; McNaughton, Peter A

2006-05-10

Small mammalian proteins called the prokineticins [prokineticin 1 (PK1) and PK2] and two corresponding G-protein-coupled receptors [prokineticin receptor 1 (PKR1) and PKR2] have been identified recently, but the physiological role of the PK/PKR system remains mostly unexplored. Bv8, a protein extracted from frog skin, is a convenient and potent agonist for both PKR1 and PKR2, and injection of Bv8 in vivo causes a potent and long-lasting hyperalgesia. Here, we investigate the cellular basis of hyperalgesia caused by activation of PKRs. Bv8 caused increases in [Ca]i in a population of isolated dorsal root ganglion (DRG) neurons, which we identified as nociceptors, or sensors for painful stimuli, from their responses to capsaicin, bradykinin, mustard oil, or proteases. Bv8 enhanced the inward current carried by the heat and capsaicin receptor, transient receptor potential vanilloid 1 (TRPV1) via a pathway involving activation of protein kinase Cepsilon (PKCepsilon), because Bv8 caused translocation of PKCepsilon to the neuronal membrane and because PKC antagonists reduced both the enhancement of current carried by TRPV1 and behavioral hyperalgesia in rodents. The neuronal population expressing PKRs consisted partly of small peptidergic neurons and partly of neurons expressing the N52 marker for myelinated fibers. Using single-cell reverse transcriptase-PCR, we found that mRNA for PKR1 was mainly expressed in small DRG neurons. Exposure to GDNF (glial cell line-derived neurotrophic factor) induced de novo expression of functional receptors for Bv8 in a nonpeptidergic population of neurons. These results show that prokineticin receptors are expressed in nociceptors and cause heat hyperalgesia by sensitizing TRPV1 through activation of PKCepsilon. The results suggest a role for prokineticins in physiological inflammation and hyperalgesia.

Putting Technology to Work in Science - How to Select Unmanned Aerial Vehicles (UAV) and their Instrumentation for Atmospheric and Earth Surface Observations

NASA Astrophysics Data System (ADS)

Teller, Amit; Lange, Manfred; Ioannou, Stelios; Keleshis, Christos

2010-05-01

The Autonomous Flying Platforms for Atmospheric and Earth Surface Observations project (APAESO) of the Energy, Environment and Water Research Center (EEWRC) at the Cyprus Institute is aimed at the dual purpose of carrying out atmospheric and earth-surface observations in the Mediterranean. The APAESO platforms will offer the unique potential to determine physical, chemical and radiative atmospheric properties, aerosol and dust concentrations, atmospheric dynamics, surface morphology, vegetation and land use patterns as well as ocean surface properties (biology, waves, currents) and to carry out archaeological site reconnaissance and contaminant detection at high spatial resolution. The first phase of APAESO was dedicated to the preliminary design and the selection of an Unmanned Aerial Vehicle (UAV) as the backbone of the APAESO infrastructure. Selection of a UAV suitable for the many research objectives as outlined above is challenging because the UAV technology is new and rapidly evolving. This notwithstanding, a very large number of systems, mostly utilized for defense purposes, are currently available. The major challenge in the selection process lies in considering the trade-off between different platform characteristics (e.g. payload weight, endurance, max. altitude for operation and price) and in optimizing the potential performance of the UAV. Based on the required characteristics for the UAV platform, a survey of possible UAVs and suitable sensors was prepared based on various data sources. We used an elimination process in order to consider only a few models for the final selection process out of about 1000 commercially available UAV models that were initially investigated. The presentation will discuss the main scientific objectives that determine the specification of the UAV platform, major considerations in selecting best available technology for our needs and will briefly describe the next phases of the project.

Diversification of the Salmonella Fimbriae: A Model of Macro- and Microevolution

PubMed Central

Yue, Min; Rankin, Shelley C.; Blanchet, Ryan T.; Nulton, James D.; Edwards, Robert A.; Schifferli, Dieter M.

2012-01-01

Bacteria of the genus Salmonella comprise a large and evolutionary related population of zoonotic pathogens that can infect mammals, including humans and domestic animals, birds, reptiles and amphibians. Salmonella carries a plethora of virulence genes, including fimbrial adhesins, some of them known to participate in mammalian or avian host colonization. Each type of fimbria has its structural subunit and biogenesis genes encoded by one fimbrial gene cluster (FGC). The accumulation of new genomic information offered a timely opportunity to better evaluate the number and types of FGCs in the Salmonella pangenome, to test the use of current classifications based on phylogeny, and to infer potential correlations between FGC evolution in various Salmonella serovars and host niches. This study focused on the FGCs of the currently deciphered 90 genomes and 60 plasmids of Salmonella. The analysis highlighted a fimbriome consisting of 35 different FGCs, of which 16 were new, each strain carrying between 5 and 14 FGCs. The Salmonella fimbriome was extremely diverse with FGC representatives in 8 out of 9 previously categorized fimbrial clades and subclades. Phylogenetic analysis of Salmonella suggested macroevolutionary shifts detectable by extensive FGC deletion and acquisition. In addition, microevolutionary drifts were best depicted by the high level of allelic variation in predicted or known adhesins, such as the type 1 fimbrial adhesin FimH for which 67 different natural alleles were identified in S. enterica subsp. I. Together with strain-specific collections of FGCs, allelic variation among adhesins attested to the pathoadaptive evolution of Salmonella towards specific hosts and tissues, potentially modulating host range, strain virulence, disease progression, and transmission efficiency. Further understanding of how each Salmonella strain utilizes its panel of FGCs and specific adhesin alleles for survival and infection will support the development of new approaches for the control of Salmonellosis. PMID:22701679

Structured inspection of medications carried and stored by emergency medical services agencies identifies practices that may lead to medication errors.

PubMed

Kupas, Douglas F; Shayhorn, Meghan A; Green, Paul; Payton, Thomas F

2012-01-01

Medications are essential to emergency medical services (EMS) agencies when providing lifesaving care, but the EMS environment has challenges related to safe medication storage when compared with a hospital setting. We developed a structured process, based on common pharmacy practices, to review medications carried by EMS agencies to identify situations that may lead to medication error and to determine some best practices that may reduce potential errors and the risk of patient harm. To provide a descriptive account of EMS practices related to carrying and storing medications that have the potential for causing a medication administration error or patient harm. Using a structured process for inspection, an emergency medicine pharmacist and emergency physician(s) reviewed the medication carrying and storage practices of all nine advanced life support ambulance agencies within a five-county EMS region. Each medication carried and stored by the EMS agency was inspected for predetermined and spontaneously observed issues that could lead to medication error. These issues were documented and photographed. Two EMS medical directors reviewed each potential error for the risk of producing patient harm and assigned each to a category of high, moderate, or low risk. Because issues of temperature on EMS medications have been addressed elsewhere, this study concentrated on potential for EMS medication administration errors exclusive of storage temperatures. When reviewing medications carried by the nine EMS agencies, 38 medication safety issues were identified (range 1 to 8 per EMS agency). Of these, 16 were considered to be high risk, 14 moderate risk, and eight low risk for patient harm. Examples of potential issues included carrying expired medications, container-labeling issues, different medications stored in look-alike vials or prefilled syringes in the same compartment, and carrying crystalloid solutions next to solutions premixed with a medication. When reviewing medications stored at the EMS agency stations, eight safety issues were identified (range from 0 to 4 per station), including five moderate-risk and three low-risk issues. No agency had any high-risk medication issues related to storage of medication stock in the station. We observed potential medication safety issues related to how medications are carried and stored at all nine EMS agencies in a five-county region. Understanding these issues may assist EMS agencies in reducing the potential for a medication error and risk of patient harm. More research is needed to determine whether following these suggested best practices for carrying medications on EMS vehicles actually reduces errors in medication administration by EMS providers or decreases patient harm.

Improving Public Health DSSs by Including Saharan Dust Forecasts Through Incorporation of NASA's GOCART Model Results

NASA Technical Reports Server (NTRS)

Berglund, Judith

2007-01-01

Approximately 2-3 billion metric tons of soil dust are estimated to be transported in the Earth's atmosphere each year. Global transport of desert dust is believed to play an important role in many geochemical, climatological, and environmental processes. This dust carries minerals and nutrients, but it has also been shown to carry pollutants and viable microorganisms capable of harming human, animal, plant, and ecosystem health. Saharan dust, which impacts the eastern United States (especially Florida and the southeast) and U.S. Territories in the Caribbean primarily during the summer months, has been linked to increases in respiratory illnesses in this region and has been shown to carry other human, animal, and plant pathogens. For these reasons, this candidate solution recommends integrating Saharan dust distribution and concentration forecasts from the NASA GOCART global dust cycle model into a public health DSS (decision support system), such as the CDC's (Centers for Disease Control and Prevention's) EPHTN (Environmental Public Health Tracking Network), for the eastern United States and Caribbean for early warning purposes regarding potential increases in respiratory illnesses or asthma attacks, potential disease outbreaks, or bioterrorism. This candidate solution pertains to the Public Health National Application but also has direct connections to Air Quality and Homeland Security. In addition, the GOCART model currently uses the NASA MODIS aerosol product as an input and uses meteorological forecasts from the NASA GEOS-DAS (Goddard Earth Observing System Data Assimilation System) GEOS-4 AGCM. In the future, VIIRS aerosol products and perhaps CALIOP aerosol products could be assimilated into the GOCART model to improve the results.

On the use of information theory for the analysis of synchronous nociceptive withdrawal reflexes and somatosensory evoked potentials elicited by graded electrical stimulation.

PubMed

Arguissain, Federico G; Biurrun Manresa, José A; Mørch, Carsten D; Andersen, Ole K

2015-01-30

To date, few studies have combined the simultaneous acquisition of nociceptive withdrawal reflexes (NWR) and somatosensory evoked potentials (SEPs). In fact, it is unknown whether the combination of these two signals acquired simultaneously could provide additional information on somatosensory processing at spinal and supraspinal level compared to individual NWR and SEP signals. By using the concept of mutual information (MI), it is possible to quantify the relation between electrical stimuli and simultaneous elicited electrophysiological responses in humans based on the estimated stimulus-response signal probability distributions. All selected features from NWR and SEPs were informative in regard to the stimulus when considered individually. Specifically, the information carried by NWR features was significantly higher than the information contained in the SEP features (p<0.05). Moreover, the joint information carried by the combination of features showed an overall redundancy compared to the sum of the individual contributions. Comparison with existing methods MI can be used to quantify the information that single-trial NWR and SEP features convey, as well as the information carried jointly by NWR and SEPs. This is a model-free approach that considers linear and non-linear correlations at any order and is not constrained by parametric assumptions. The current study introduces a novel approach that allows the quantification of the individual and joint information content of single-trial NWR and SEP features. This methodology could be used to decode and interpret spinal and supraspinal interaction in studies modulating the responsiveness of the nociceptive system. Copyright © 2014 Elsevier B.V. All rights reserved.

A linear helicon plasma device with controllable magnetic field gradient

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barada, Kshitish K.; Chattopadhyay, P. K.; Ghosh, J.

2012-06-15

Current free double layers (CFDLs) are localized potential structures having spatial dimensions - Debye lengths and potential drops of more than local electron temperature across them. CFDLs do not need a current for them to be sustained and hence they differ from the current driven double layers. Helicon antenna produced plasmas in an expanded chamber along with an expanding magnetic field have shown the existence of CFDL near the expansion region. A helicon plasma device has been designed, fabricated, and installed in the Institute for Plasma Research, India to study the role of maximum magnetic field gradient as well asmore » its location with respect to the geometrical expansion region of the chamber in CFDL formation. The special feature of this machine consisting of two chambers of different radii is its capability of producing different magnetic field gradients near the physical boundary between the two chambers either by changing current in one particular coil in the direction opposite to that in other coils and/or by varying the position of this particular coil. Although, the machine is primarily designed for CFDL experiments, it is also capable of carrying out many basic plasma physics experiments such as wave propagation, wave coupling, and plasma instabilities in a varying magnetic field topology. In this paper, we will present the details of the machine construction, its specialties, and some preliminary results about the production and characterization of helicon plasma in this machine.« less

Pharmacological modulations of cardiac ultra-rapid and slowly activating delayed rectifier currents: potential antiarrhythmic approaches.

PubMed

Islam, Mohammed A

2010-01-01

Despite the emerging new insights into our understandings of the cellular mechanisms underlying cardiac arrhythmia, medical therapy for this disease remains unsatisfactory. Atrial fibrillation (AF), the most prevalent arrhythmia, is responsible for significant morbidity and mortality. On the other hand, ventricular fibrillation results in sudden cardiac deaths in many instances. Prolongation of cardiac action potential (AP) is a proven principle of antiarrhythmic therapy. Class III antiarrhythmic agents prolong AP and QT interval by blocking rapidly activating delayed rectifier current (I(Kr)). However, I(Kr) blocking drugs carry the risk of life-threatening proarrhythmia. Recently, modulation of atrial-selective ultra-rapid delayed rectifier current (I(Kur)), has emerged as a novel therapeutic approach to treat AF. A number of I(Kur) blockers are being evaluated for the treatment of AF. The inhibition of slowly activating delayed rectifier current (I(Ks)) has also been proposed as an effective and safer antiarrhythmic approach because of its distinguishing characteristics that differ in remarkable ways from other selective class III agents. Selective I(Ks) block may prolong AP duration (APD) at rapid rates without leading to proarrhythmia. This article reviews the pathophysiological roles of I(Kur) and I(Ks) in cardiac repolarization and the implications of newly developed I(Kur) and I(Ks) blocking agents as promising antiarrhythmic approaches. Several recent patents pertinent to antiarrhythmic drug development have been discussed. Further research will be required to evaluate the efficacy and safety of these agents in the clinical setting.

Methods for locating ground faults and insulation degradation condition in energy conversion systems

DOEpatents

Agamy, Mohamed; Elasser, Ahmed; Galbraith, Anthony William; Harfman Todorovic, Maja

2015-08-11

Methods for determining a ground fault or insulation degradation condition within energy conversion systems are described. A method for determining a ground fault within an energy conversion system may include, in part, a comparison of baseline waveform of differential current to a waveform of differential current during operation for a plurality of DC current carrying conductors in an energy conversion system. A method for determining insulation degradation within an energy conversion system may include, in part, a comparison of baseline frequency spectra of differential current to a frequency spectra of differential current transient at start-up for a plurality of DC current carrying conductors in an energy conversion system. In one embodiment, the energy conversion system may be a photovoltaic system.

Electrohydrolysis pretreatment for enhanced methane production from lignocellulose waste pulp and paper mill sludge and its kinetics.

PubMed

Veluchamy, C; Raju, V Wilson; Kalamdhad, Ajay S

2018-03-01

A novel electrohydrolysis pretreatment enhances methane production from lignocellulose material during anaerobic digestion. A biochemical methane potential assay was carried out to determine the effect of direct current and the efficacy of electrohydrolysis pretreatment on biogas production. Methane yield was increased by 13.8%, to 301 ± 3 mL CH 4 /g VS, when lignocellulosic waste was pretreated with electrohydrolysis. A net energy gain of 13,224 kJ was realized after electrohydrolysis pretreatment, which was 1.51 times higher than reported for thermal pretreatment. In addition, two kinetic models were used, including the modified Gompertz model to reproduce the experimental data. These finding support the potential for increased methane recovery from lignocellulosic waste using electrohydrolysis as a pretreatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Reprocessing of LiH in Molten Chlorides

NASA Astrophysics Data System (ADS)

Masset, Patrick J.; Gabriel, Armand; Poignet, Jean-Claude

2008-06-01

LiH was used as inactive material to stimulate the reprocessing of lithium tritiate in molten chlorides. The electrochemical properties (diffusion coefficients, apparent standard potentials) were measured by means of transient electrochemical techniques (cyclic voltammetry and chronopotentiometry). At 425 ºC the diffusion coefficient and the apparent standard potential were 2.5 · 10-5 cm2 s-1 and -1.8 V vs. Ag/AgCl, respectively. For the process design the LiH solubility was measured by means of DTA to optimize the LiH concentration in the molten phase. In addition electrolysis tests were carried out at 460 ºC with current densities up to 1 A cm-2 over 24 h. These results show that LiH may be reprocessed in molten chlorides consisting in the production of hydrogen gas at the anode and molten metallic lithium at the cathode.

Mimics and chameleons in motor neurone disease

PubMed Central

Turner, Martin R; Talbot, Kevin

2013-01-01

The progression of motor neurone disease (MND) is currently irreversible, and the grave implications of diagnosis naturally fuels concern among neurologists over missing a potential mimic disorder. There is no diagnostic test for MND but in reality there are few plausible mimics in routine clinical practice. In the presence of a progressive pure motor disorder, signs such as florid fasciculations, bilateral tongue wasting, the ‘split hand’, head drop, emotionality, and cognitive or behavioural impairment carry high positive predictive value. MND is clinically heterogeneous, however, with some important chameleon-like presentations and considerable variation in clinical course. Lack of confidence about the scope of such variation, or an approach to diagnosis emphasising investigations over clinical common sense, has the potential to exacerbate diagnostic delay in MND and impede timely planning of the care which is essential to maximising quality of life. PMID:23616620

Molecular Dynamics simulations of Inhibitor of Apoptosis Proteins and identification of potential small molecule inhibitors.

PubMed

Jayakumar, Jayanthi; Anishetty, Sharmila

2014-05-01

Chemotherapeutic resistance due to over expression of Inhibitor of Apoptosis Proteins (IAPs) XIAP, survivin and livin has been observed in various cancers. In the current study, Molecular Dynamics (MD) simulations were carried out for all three IAPs and a common ligand binding scaffold was identified. Further, a novel sequence based motif specific to these IAPs was designed. SMAC is an endogenous inhibitor of IAPs. Screening of ChemBank for compounds similar to lead SMAC-non-peptidomimetics yielded a cemadotin related compound NCIMech_000654. Cemadotin is a derivative of natural anti-tumor peptide dolastatin-15; hence these compounds were docked against all three IAPs. Based on our analysis, we propose that NCIMech_000654/dolastatin-15/cemadotin derivatives may be investigated for their potential in inhibiting XIAP, survivin and livin. Copyright © 2014 Elsevier Ltd. All rights reserved.

Missed therapeutic and prevention opportunities in women with BRCA-mutated epithelial ovarian cancer and their families due to low referral rates for genetic counseling and BRCA testing: A review of the literature.

PubMed

Hoskins, Paul J; Gotlieb, Walter H

2017-11-01

Answer questions and earn CME/CNE Fifteen percent of women with epithelial ovarian cancer have inherited mutations in the BRCA breast cancer susceptibility genes. Knowledge of her BRCA status has value both for the woman and for her family. A therapeutic benefit exists for the woman with cancer, because a new family of oral drugs, the poly ADP-ribose polymerase (PARP) inhibitors, has recently been approved, and these drugs have the greatest efficacy in women who carry the mutation. For her family, there is the potential to prevent ovarian cancer in those carrying the mutation by using risk-reducing surgery. Such surgery significantly reduces the chance of developing this, for the most part, incurable cancer. Despite these potential benefits, referral rates for genetic counseling and subsequent BRCA testing are low, ranging from 10% to 30%, indicating that these therapeutic and prevention opportunities are being missed. The authors have reviewed the relevant available literature. Topics discussed are BRCA and its relation to ovarian cancer, the rates of referral for genetic counseling/BRCA testing, reasons for these low rates, potential strategies to improve on those rates, lack of effectiveness of current screening strategies, the pros and cons of risk-reducing surgery, other prevention options, and the role and value of PARP inhibitors. CA Cancer J Clin 2017;67:493-506. © 2017 American Cancer Society. © 2017 American Cancer Society.

Predatory fish depletion and recovery potential on Caribbean reefs

PubMed Central

Valdivia, Abel; Cox, Courtney Ellen; Bruno, John Francis

2017-01-01

The natural, prehuman abundance of most large predators is unknown because of the lack of historical data and a limited understanding of the natural factors that control their populations. Determining the supportable predator biomass at a given location (that is, the predator carrying capacity) would help managers to optimize protection and would provide site-specific recovery goals. We assess the relationship between predatory reef fish biomass and several anthropogenic and environmental variables at 39 reefs across the Caribbean to (i) estimate their roles determining local predator biomass and (ii) determine site-specific recovery potential if fishing was eliminated. We show that predatory reef fish biomass tends to be higher in marine reserves but is strongly negatively related to human activities, especially coastal development. However, human activities and natural factors, including reef complexity and prey abundance, explain more than 50% of the spatial variation in predator biomass. Comparing site-specific predator carrying capacities to field observations, we infer that current predatory reef fish biomass is 60 to 90% lower than the potential supportable biomass in most sites, even within most marine reserves. We also found that the scope for recovery varies among reefs by at least an order of magnitude. This suggests that we could underestimate unfished biomass at sites that provide ideal conditions for predators or greatly overestimate that of seemingly predator-depleted sites that may have never supported large predator populations because of suboptimal environmental conditions. PMID:28275730

In situ propellant production: Alternatives for Mars exploration

NASA Technical Reports Server (NTRS)

Stancati, Michael L.; Jacobs, Mark K.; Cole, Kevin J.; Collins, John T.

1991-01-01

Current planning for the Space Exploration Initiative (SEI) recognizes the need for extraterrestrial resources to sustain long-term human presence and to attain some degree of self-sufficiency. As a practical matter, reducing the need to carry large supplies of propellant from Earth will make space exploration more economical. For nearly every round trip planned with conventional propulsion, the actual payload is only a small fraction - perhaps 10-15 percent - of the mass launched from Earth. The objective of this study was to analyze the potential application for SEI missions of propellants made exclusively from lunar or martian resources. Using such propellants could minimize or eliminate the cost of carrying propellant for surface excursion vehicles and return transfers through two high-energy maneuvers: Earth launch and trans-Mars injection. Certain chemical mono- and bipropellants are candidates for this approach; they could be recovered entirely from in situ resources on the Moon and Mars, without requiring a continuing Earth-based resupply of propellant constituents (e.g., fuel to mix with a locally obtained oxidizer) and, perhaps, with minimal need to resupply consumables (e.g., reagents or catalyst for process reactions). A complete assessment of the performance potential of these propellants must include the requirements for installation, operations, maintenance, and resupply of the chemical processing facility.

Electrochemical studies in aluminum chloride melts

NASA Technical Reports Server (NTRS)

Osteryoung, R. A.

1971-01-01

A melt purification system was developed which produces a final melt far superior electrochemically than those previously reported. A residual current of less than 2 microamps/sq mn at a sweep rate of 0.5 V/sec was used as the criteria for a pure melt. The use of a second purified bulk melt and a heated pipette permitted the rapid exchange of working electrode compartments while retaining the same reference electrode system. The major portion of the work was carried out in the 1:1 AlCl3:NaCl melt at 175 and 200 C. Several measurements were made in the 2:1 melt and a few on the silver systems in intermediate compositions. Programs for PDP-8I and PDP-12 digital computers and the required electronic circuitry systems were developed to carry out various electrochemical measurements in the melt. A pair of 50 yard transmission lines were used to connect the computer to the experiment. Ensemble averaging and digital, least squares smoothing are used within the programs to improve the signal-to-noise ratio by at least an order of magnitude. Some of the computerized electrochemcial techniques used to examine the different systems were pulse polarography, double pulse polarography, staircase voltammetry, kinetic double potential step chronoamperometry and double potential step chronocoulometry.

Analysis of the Effects of Calcium or Magnesium on Voltage-Clamp Currents in Perfused Squid Axons Bathed in Solutions of High Potassium

PubMed Central

Rojas, Eduardo; Taylor, Robert E.; Atwater, Illani; Bezanilla, Francisco

1969-01-01

Isolated axons from the squid, Dosidicus gigas, were internally perfused with potassium fluoride solutions. Membrane currents were measured following step changes of membrane potential in a voltage-clamp arrangement with external isosmotic solution changes in the order: potassium-free artificial seawater; potassium chloride; potassium chloride containing 10, 25, 40 or 50, mM calcium or magnesium; and potassium-free artificial seawater. The following results suggest that the currents measured under voltage clamp with potassium outside and inside can be separated into two components and that one of them, the predominant one, is carried through the potassium system. (a) Outward currents in isosmotic potassium were strongly and reversibly reduced by tetraethylammonium chloride. (b) Without calcium or magnesium a progressive increase in the nontime-dependent component of the currents (leakage) occurred. (c) The restoration of calcium or magnesium within 15–30 min decreases this leakage. (d) With 50 mM divalent ions the steady-state current-voltage curve was nonlinear with negative resistance as observed in intact axons in isosmotic potassium. (e) The time-dependent components of the membrane currents were not clearly affected by calcium or magnesium. These results show a strong dependence of the leakage currents on external calcium or magnesium concentration but provide no support for the involvement of calcium or magnesium in the kinetics of the potassium system. PMID:5823216

Analysis of the effects of calcium or magnesium on voltage-clamp currents in perfused squid axons bathed in solutions of high potassium.

PubMed

Rojas, E; Taylor, R E; Atwater, I; Bezanilla, F

1969-10-01

Isolated axons from the squid, Dosidicus gigas, were internally perfused with potassium fluoride solutions. Membrane currents were measured following step changes of membrane potential in a voltage-clamp arrangement with external isosmotic solution changes in the order: potassium-free artificial seawater; potassium chloride; potassium chloride containing 10, 25, 40 or 50, mM calcium or magnesium; and potassium-free artificial seawater. The following results suggest that the currents measured under voltage clamp with potassium outside and inside can be separated into two components and that one of them, the predominant one, is carried through the potassium system. (a) Outward currents in isosmotic potassium were strongly and reversibly reduced by tetraethylammonium chloride. (b) Without calcium or magnesium a progressive increase in the nontime-dependent component of the currents (leakage) occurred. (c) The restoration of calcium or magnesium within 15-30 min decreases this leakage. (d) With 50 mM divalent ions the steady-state current-voltage curve was nonlinear with negative resistance as observed in intact axons in isosmotic potassium. (e) The time-dependent components of the membrane currents were not clearly affected by calcium or magnesium. These results show a strong dependence of the leakage currents on external calcium or magnesium concentration but provide no support for the involvement of calcium or magnesium in the kinetics of the potassium system.

A plug flow reactor model of a vanadium redox flow battery considering the conductive current collectors

NASA Astrophysics Data System (ADS)

König, S.; Suriyah, M. R.; Leibfried, T.

2017-08-01

A lumped-parameter model for vanadium redox flow batteries, which use metallic current collectors, is extended into a one-dimensional model using the plug flow reactor principle. Thus, the commonly used simplification of a perfectly mixed cell is no longer required. The resistances of the cell components are derived in the in-plane and through-plane directions. The copper current collector is the only component with a significant in-plane conductance, which allows for a simplified electrical network. The division of a full-scale flow cell into 10 layers in the direction of fluid flow represents a reasonable compromise between computational effort and accuracy. Due to the variations in the state of charge and thus the open circuit voltage of the electrolyte, the currents in the individual layers vary considerably. Hence, there are situations, in which the first layer, directly at the electrolyte input, carries a multiple of the last layer's current. The conventional model overestimates the cell performance. In the worst-case scenario, the more accurate 20-layer model yields a discharge capacity 9.4% smaller than that computed with the conventional model. The conductive current collector effectively eliminates the high over-potentials in the last layers of the plug flow reactor models that have been reported previously.

Perioperative hair removal: A review of best practice and a practice improvement opportunity.

PubMed

Spencer, Maureen; Barnden, Marsha; Johnson, Helen Boehm; Fauerbach, Loretta Litz; Graham, Denise; Edmiston, Charles E

2018-06-01

The current practice of perioperative hair removal reflects research-driven changes designed to minimize the risk of surgical wound infection. An aspect of the practice which has received less scrutiny is the clean-up of the clipped hair. This process is critical. The loose fibers represent a potential infection risk because of the micro-organisms they can carry, but their clean-up can pose a logistical problem because of the time required to remove them. Research has demonstrated that the most commonly employed means of clean-up, the use of adhesive tape or sticky mitts, can be both ineffective and time-consuming in addition to posing an infection risk from cross-contamination. Recently published research evaluating surgical clippers fitted with a vacuum-assisted hair collection device highlights the potential for significant practice improvement in the perioperative hair removal clean-up process. These improvements include not only further mitigation of potential infection risk but also substantial OR time and cost savings.

Artifacts produced during electrical stimulation of the vestibular nerve in cats. [autonomic nervous system components of motion sickness

NASA Technical Reports Server (NTRS)

Tang, P. C.

1973-01-01

Evidence is presented to indicate that evoked potentials in the recurrent laryngeal, the cervical sympathetic, and the phrenic nerve, commonly reported as being elicited by vestibular nerve stimulation, may be due to stimulation of structures other than the vestibular nerve. Experiments carried out in decerebrated cats indicated that stimulation of the petrous bone and not that of the vestibular nerve is responsible for the genesis of evoked potentials in the recurrent laryngeal and the cervical sympathetic nerves. The phrenic response to electrical stimulation applied through bipolar straight electrodes appears to be the result of stimulation of the facial nerve in the facial canal by current spread along the petrous bone, since stimulation of the suspended facial nerve evoked potentials only in the phrenic nerve and not in the recurrent laryngeal nerve. These findings indicate that autonomic components of motion sickness represent the secondary reactions and not the primary responses to vestibular stimulation.

Semantic parafoveal-on-foveal effects and preview benefits in reading: Evidence from Fixation Related Potentials.

PubMed

López-Peréz, P J; Dampuré, J; Hernández-Cabrera, J A; Barber, H A

2016-11-01

During reading parafoveal information can affect the processing of the word currently fixated (parafovea-on-fovea effect) and words perceived parafoveally can facilitate their subsequent processing when they are fixated on (preview effect). We investigated parafoveal processing by simultaneously recording eye movements and EEG measures. Participants read word pairs that could be semantically associated or not. Additionally, the boundary paradigm allowed us to carry out the same manipulation on parafoveal previews that were displayed until reader's gaze moved to the target words. Event Related Potentials time-locked to the prime-preview presentation showed a parafoveal-on-foveal N400 effect. Fixation Related Potentials time locked to the saccade offset showed an N400 effect related to the prime-target relationship. Furthermore, this later effect interacted with the semantic manipulation of the previews, supporting a semantic preview benefit. These results demonstrate that at least under optimal conditions foveal and parafoveal information can be simultaneously processed and integrated. Copyright © 2016 Elsevier Inc. All rights reserved.

Multireference configuration interaction calculations of the first six ionization potentials of the uranium atom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bross, David H.; Parmar, Payal; Peterson, Kirk A.

The first 6 ionization potentials (IPs) of the uranium atom have been calculated using multireference configuration interaction (MRCI+Q) with extrapolations to the complete basis set (CBS) limit using new all-electron correlation consistent basis sets. The latter were carried out with the third-order Douglas-Kroll-Hess Hamiltonian. Correlation down through the 5s5p5d electrons have been taken into account, as well as contributions to the IPs due to the Lamb shift. Spin-orbit coupling contributions calculated at the 4-component Kramers restricted configuration interaction level, as well as the Gaunt term computed at the Dirac-Hartree-Fock level, were added to the best scalar relativistic results. As amore » result, the final ionization potentials are expected to be accurate to at least 5 kcal/mol (0.2 eV), and thus more reliable than the current experimental values of IP 3 through IP 6.« less

Studies of the system-environment interaction by electron beam emission from a sounding rocket payload in the ionosphere

NASA Astrophysics Data System (ADS)

Myers, Neil Brubaker

The CHARGE-2 sounding rocket payload was designed to measure the transient and steady-state electrical charging of a space vehicle at low-Earth-orbit altitudes during the emission of a low-power electron beam from the vehicle. In addition to the electron gun, the payload contained several diagnostics to monitor plasma and waves resulting from the beam/space/vehicle interaction. The payload was separated into two sections, the larger section carried a 1-keV electron gun and was referred to as the mother vehicle. The smaller section, referred to as the daughter, was connected to the mother by an insulated, conducting tether and was deployed to a distance of up to 426 m across the geomagnetic field. Payload stabilization was obtained using thrusters that released cold nitrogen gas. In addition to performing electron beam experiments, the mother vehicle contained a high-voltage power supply capable of applying up to +450 V and 28 mA to the daughter through the tether. Steady-state potentials of up to 560 V were measured for the mother vehicle. The daughter attained potentials of up to 1000 V relative to the background ionosphere and collected currents up to 6.5 mA. Thruster firings increased the current collection to the vehicle firing the thrusters and resulted in neutralization of the payload. The CHARGE-2 experiment was unique in that for the first time a comparison was made of the current collection between an electron beam-emitting vehicle and a non-emitting vehicle at high potential.

Enhanced Monitoring of Nanosecond Electric Pulse-Evoked Membrane Conductance Changes in Whole-Cell Patch Clamp Experiments.

PubMed

Yoon, Jihwan; Leblanc, Normand; Zaklit, Josette; Vernier, P Thomas; Chatterjee, Indira; Craviso, Gale L

2016-10-01

Patch clamp electrophysiology serves as a powerful method for studying changes in plasma membrane ion conductance induced by externally applied high-intensity nanosecond electric pulses (NEPs). This paper describes an enhanced monitoring technique that minimizes the length of time between pulse exposure and data recording in a patch-clamped excitable cell. Whole-cell membrane currents were continuously recorded up to 11 ms before and resumed 8 ms after delivery of a 5-ns, 6 MV/m pulse by a pair of tungsten rod electrodes to a patched adrenal chromaffin cell maintained at a holding potential of -70 mV. This timing was achieved by two sets of relay switches. One set was used to disconnect the patch pipette electrode from the pre-amplifier and connect it to a battery to maintain membrane potential at -70 mV, and also to disconnect the reference electrode from the amplifier. The other set was used to disconnect the electrodes from the pulse generator until the time of NEP/sham exposure. The sequence and timing of both sets of relays were computer-controlled. Using this procedure, we observed that a 5-ns pulse induced an instantaneous inward current that decayed exponentially over the course of several minutes, that a second pulse induced a similar response, and that the current was carried, at least in part, by Na + . This approach for characterizing ion conductance changes in an excitable cell in response to NEPs will yield information essential for assessing the potential use of NEP stimulation for therapeutic applications.

Functional Neuronal Processing of Human Body Odors

PubMed Central

Lundström, Johan N.; Olsson, Mats J.

2013-01-01

Body odors carry informational cues of great importance for individuals across a wide range of species, and signals hidden within the body odor cocktail are known to regulate several key behaviors in animals. For a long time, the notion that humans may be among these species has been dismissed. We now know, however, that each human has a unique odor signature that carries information related to his or her genetic makeup, as well as information about personal environmental variables, such as diet and hygiene. Although a substantial number of studies have investigated the behavioral effects of body odors, only a handful have studied central processing. Recent studies have, however, demonstrated that the human brain responds to fear signals hidden within the body odor cocktail, is able to extract kin specific signals, and processes body odors differently than other perceptually similar odors. In this chapter, we provide an overview of the current knowledge of how the human brain processes body odors and the potential importance these signals have for us in everyday life. PMID:20831940

A global range military transport: The ostrich

NASA Technical Reports Server (NTRS)

Aguiar, John; Booker, Cecilia; Hoffman, Eric; Kramar, James; Manahan, Orlando; Serranzana, Ray; Taylor, Mike

1993-01-01

Studies have shown that there is an increasing need for a global range transport capable of carrying large numbers of troops and equipment to potential trouble spots throughout the world. The Ostrich is a solution to this problem. The Ostrich is capable of carrying 800,000 pounds 6,500 n.m. and returning with 15 percent payload, without refueling. With a technology availability date in 2010 and an initial operating capability of 2015, the aircraft incorporates many advanced technologies including laminar flow control, composite primary structures, and a unique multibody design. By utilizing current technology, such as using McDonnell Douglas C-17 fuselage for the outer fuselages on the Ostrich, the cost for the aircraft was reduced. The cost of the Ostrich per aircraft is $1.2 billion with a direct operating cost of $56,000 per flight hour. The Ostrich will provide a valuable service as a logistical transport capable of rapidly projecting a significant military force or humanitarian aid anywhere in the world.

Solar Polar ORbit Telescope (SPORT): A Potential Space Weather Mission of China

NASA Astrophysics Data System (ADS)

Liu, Y. D.; Xiong, M.; Wu, J.; Liu, H.; Zheng, J.; Li, B.; Zhang, C.; Sun, W.

2013-12-01

We describe a spacecraft mission, named Solar Polar ORbit Telescope (SPORT), which is currently under a scientific and engineering background study in China. SPORT was originally proposed in 2004 by the National Space Science Center, Chinese Academy of Sciences. It will carry a suite of remote-sensing and in-situ instruments to observe coronal mass ejections (CMEs), solar high-latitude magnetism, and the fast solar wind from a polar orbit around the Sun. It is intended to be the first mission that carries remote-sensing instruments from a high-latitude orbit around the Sun, the first mission that could image interplanetary CMEs at radio wavelengths from space, and the first mission that could measure solar high-latitude magnetism leading to eruptions and the fast solar wind. The first extended view of the polar region of the Sun and the ecliptic plane enabled by SPORT will provide a unique opportunity to study CME propagation through the inner heliosphere and solar high-latitude magnetism giving rise to eruptions and the fast solar wind.

Presence of entomobirnaviruses in Chinese mosquitoes in the absence of Dengue virus co-infection.

PubMed

Huang, Yong; Mi, Zhiqiang; Zhuang, Lu; Ma, Maijuan; An, Xiaoping; Liu, Wei; Cao, Wuchun; Tong, Yigang

2013-03-01

Birnaviruses, including the genus Entomobirnavirus, are socio-economically important viruses. Currently, only Drosophila X virus has been formally assigned to the genus Entomobirnavirus, but two more viruses were recently isolated, Espirito Santo virus (ESV) and Culex Y virus. The host mosquito has been reported to carry many viruses, but seldom entomobirnaviruses. To discover potential pathogens in mosquitoes, we exploited small-RNAs high-throughput sequencing of three mosquito species caught in South China. A virus that genetically likes entomobirnavirus, Mosquito X virus (MXV), was identified from Anopheles sinensis and was 97% identical to ESV, which co-infects with Dengue virus (DENV). However, the absence of DENV in the A. sinensis suggested the independence of MXV infection from dengue co-infection. Our discovery complements prior research on entomobirnaviruses and proved that MXV may be widespread in mosquitoes on different continents. This work also highlights the applying of high-throughput sequencing of small RNAs to survey viruses carried by insect vectors.

Hawking fluxes, fermionic currents, W{sub 1+{infinity}} algebra, and anomalies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonora, L.; Cvitan, M.; Theoretical Physics Department, Faculty of Science, University of Zagreb Bijenicka cesta 32, HR-10002 Zagreb

2009-10-15

We complete the analysis carried out in previous papers by studying the Hawking radiation for a Kerr black hole carried to infinity by fermionic currents of any spin. We find agreement with the thermal spectrum of the Hawking radiation for fermionic degrees of freedom. We start by showing that the near-horizon physics for a Kerr black hole is approximated by an effective two-dimensional field theory of fermionic fields. Then, starting from two-dimensional currents of any spin that form a W{sub 1+{infinity}} algebra, we construct an infinite set of covariant currents, each of which carries the corresponding moment of the Hawkingmore » radiation. All together they agree with the thermal spectrum of the latter. We show that the predictive power of this method is based not on the anomalies of the higher-spin currents (which are trivial) but on the underlying W{sub 1+{infinity}} structure. Our results point toward the existence in the near-horizon geometry of a symmetry larger than the Virasoro algebra, which very likely takes the form of a W{sub {infinity}} algebra.« less

The study method of estimation tidal flat with remote sensing waterlines

NASA Astrophysics Data System (ADS)

Gao, Zhiqiang; Liu, Xiangyang; Zhang, Yuanyuan; Liu, Chaoshun; Sun, Zhibin

2016-09-01

A tidal flat, the important potential land resource, is the sensitive area of intersection between the sea and the land. With Chinese HJ-1A/B remote sensing images of 2014 as data sources, based on the definition of a tidal flat, using DSAS software and Jenks Natural Breaks classification method synthetically, a more reasonable and accurate method of extracting tidal flat was imposed. In addition, the Bohai Rim was taken as an example to carry out investigation on the current situation of tidal flat. This paper can provide basic date and scientific evidence for rational utilization and sustainable development of tidal flat.

Malaria Molecular Epidemiology: Lessons from the International Centers of Excellence for Malaria Research Network

PubMed Central

Escalante, Ananias A.; Ferreira, Marcelo U.; Vinetz, Joseph M.; Volkman, Sarah K.; Cui, Liwang; Gamboa, Dionicia; Krogstad, Donald J.; Barry, Alyssa E.; Carlton, Jane M.; van Eijk, Anna Maria; Pradhan, Khageswar; Mueller, Ivo; Greenhouse, Bryan; Andreina Pacheco, M.; Vallejo, Andres F.; Herrera, Socrates; Felger, Ingrid

2015-01-01

Molecular epidemiology leverages genetic information to study the risk factors that affect the frequency and distribution of malaria cases. This article describes molecular epidemiologic investigations currently being carried out by the International Centers of Excellence for Malaria Research (ICEMR) network in a variety of malaria-endemic settings. First, we discuss various novel approaches to understand malaria incidence and gametocytemia, focusing on Plasmodium falciparum and Plasmodium vivax. Second, we describe and compare different parasite genotyping methods commonly used in malaria epidemiology and population genetics. Finally, we discuss potential applications of molecular epidemiological tools and methods toward malaria control and elimination efforts. PMID:26259945

Review of current interest and research in water hyacinth-based wastewater treatment

NASA Technical Reports Server (NTRS)

Markarian, R. K.; Balon, J. E.; Robinson, A. C.

1977-01-01

The status of activity in the user community for water hyacinth-based wastewater treatment was evaluated. The principal technique used was that of interviewing people who either (1) were known to be engaged in hyacinth research or development or (2) had made inquiry to NASA about hyacinth systems. About 40 non-research organizations and a similar number of research organizations were contacted. As a result of the interviews and a review of the relevant literature, it was concluded that hyacinth systems have the potential for providing a lower cost way for small cities to meet increasingly stringent effluent requirements. A limited amount of full-scale demonstration of hyacinth systems has been carried out during the past two years, but the yield of design data has been small. Several organizations are currently planning construction of experimental full-scale hyacinth-based wastewater treatment systems during 1977-1978.

Monitoring clinical progression with mitochondrial disease biomarkers

PubMed Central

Steele, Hannah E; Horvath, Rita; Lyon, Jon J; Chinnery, Patrick F

2017-01-01

Abstract Mitochondrial disorders are genetically determined metabolic diseases due to a biochemical deficiency of the respiratory chain. Given that multi-system involvement and disease progression are common features of mitochondrial disorders they carry substantial morbidity and mortality. Despite this, no disease-modifying treatments exist with clear clinical benefits, and the current best management of mitochondrial disease is supportive. Several therapeutic strategies for mitochondrial disorders are now at a mature preclinical stage. Some are making the transition into early-phase patient trials, but the lack of validated biomarkers of disease progression presents a challenge when developing new therapies for patients. This update discusses current biomarkers of mitochondrial disease progression including metabolomics, circulating serum markers, exercise physiology, and both structural and functional imaging. We discuss the advantages and disadvantages of each approach, and consider emerging techniques with a potential role in trials of new therapies. PMID:28969370

Feather corticosterone levels are related to age and future body condition, but not to subsequent fitness, in a declining migratory songbird.

PubMed

Boves, Than J; Fairhurst, Graham D; Rushing, Clark S; Buehler, David A

2016-01-01

In migratory species, breeding and non-breeding locations are geographically separate, yet the effects of conditions from one stage may carry over to affect a subsequent stage. Ideally, to understand the mechanisms and implications of 'carry-over effects', one would need to follow individuals throughout the year, quantify potential environmental causal factors and physiological mediators during multiple life-history stages, and measure downstream fitness. Owing to current limitations of tracking technology, this is impossible for small, long-distance migrants, so indirect methods to characterize carry-over effects are required. Corticosterone (CORT) is a suspected physiological mediator of carry-over effects, but when collected from blood it provides only a physiological snapshot at that point in time. When extracted from feathers, however, feather corticosterone (CORT f ) provides a measure of responses to stressors from previous, and longer, time periods. We collected feathers grown during two life-history stages (post-breeding and subsequent wintering) from individuals of two age classes of a rapidly declining migratory songbird, the cerulean warbler ( Setophaga cerulea ), on their breeding grounds and quantified CORT f concentrations. We then monitored reproduction and survival of individuals and analysed relationships among CORT f and age, body condition and future fitness. Compared with older males, second-year males had higher CORT f concentrations during both stages. When controlling for age and year, body condition at capture was positively related to CORT f concentrations from winter (especially for older birds). However, we found no relationships between CORT f and fitness (as defined by reproduction and survival). Thus, elevated CORT may represent a beneficial physiological response (e.g. hyperphagia prior to migration), particularly for certain life-history stages, and may mediate the condition in which individuals transition between stages. But for those birds that survive migration, subsequent fitness is likely determined by more recent events and local conditions (i.e. on breeding grounds), which have the potential to counteract conditions from the winter.

Comparison between numerical and analytical results on the required rf current for stabilizing neoclassical tearing modes

NASA Astrophysics Data System (ADS)

Wang, Xiaojing; Yu, Qingquan; Zhang, Xiaodong; Zhang, Yang; Zhu, Sizheng; Wang, Xiaoguang; Wu, Bin

2018-04-01

Numerical studies on the stabilization of neoclassical tearing modes (NTMs) by electron cyclotron current drive (ECCD) have been carried out based on reduced MHD equations, focusing on the amount of the required driven current for mode stabilization and the comparison with analytical results. The dependence of the minimum driven current required for NTM stabilization on some parameters, including the bootstrap current density, radial width of the driven current, radial deviation of the driven current from the resonant surface, and the island width when applying ECCD, are studied. By fitting the numerical results, simple expressions for these dependences are obtained. Analysis based on the modified Rutherford equation (MRE) has also been carried out, and the corresponding results have the same trend as numerical ones, while a quantitative difference between them exists. This difference becomes smaller when the applied radio frequency (rf) current is smaller.

Independent components of neural activity carry information on individual populations.

PubMed

Głąbska, Helena; Potworowski, Jan; Łęski, Szymon; Wójcik, Daniel K

2014-01-01

Local field potential (LFP), the low-frequency part of the potential recorded extracellularly in the brain, reflects neural activity at the population level. The interpretation of LFP is complicated because it can mix activity from remote cells, on the order of millimeters from the electrode. To understand better the relation between the recordings and the local activity of cells we used a large-scale network thalamocortical model to compute simultaneous LFP, transmembrane currents, and spiking activity. We used this model to study the information contained in independent components obtained from the reconstructed Current Source Density (CSD), which smooths transmembrane currents, decomposed further with Independent Component Analysis (ICA). We found that the three most robust components matched well the activity of two dominating cell populations: superior pyramidal cells in layer 2/3 (rhythmic spiking) and tufted pyramids from layer 5 (intrinsically bursting). The pyramidal population from layer 2/3 could not be well described as a product of spatial profile and temporal activation, but by a sum of two such products which we recovered in two of the ICA components in our analysis, which correspond to the two first principal components of PCA decomposition of layer 2/3 population activity. At low noise one more cell population could be discerned but it is unlikely that it could be recovered in experiment given typical noise ranges.

Independent Components of Neural Activity Carry Information on Individual Populations

PubMed Central

Głąbska, Helena; Potworowski, Jan; Łęski, Szymon; Wójcik, Daniel K.

2014-01-01

Local field potential (LFP), the low-frequency part of the potential recorded extracellularly in the brain, reflects neural activity at the population level. The interpretation of LFP is complicated because it can mix activity from remote cells, on the order of millimeters from the electrode. To understand better the relation between the recordings and the local activity of cells we used a large-scale network thalamocortical model to compute simultaneous LFP, transmembrane currents, and spiking activity. We used this model to study the information contained in independent components obtained from the reconstructed Current Source Density (CSD), which smooths transmembrane currents, decomposed further with Independent Component Analysis (ICA). We found that the three most robust components matched well the activity of two dominating cell populations: superior pyramidal cells in layer 2/3 (rhythmic spiking) and tufted pyramids from layer 5 (intrinsically bursting). The pyramidal population from layer 2/3 could not be well described as a product of spatial profile and temporal activation, but by a sum of two such products which we recovered in two of the ICA components in our analysis, which correspond to the two first principal components of PCA decomposition of layer 2/3 population activity. At low noise one more cell population could be discerned but it is unlikely that it could be recovered in experiment given typical noise ranges. PMID:25153730

Corrosion fatigue studies on a bulk glassy Zr-based alloy under three-point bending

NASA Astrophysics Data System (ADS)

Grell, Daniel; Wilkin, Yannic; Gostin, Petre F.; Gebert, Annett; Kerscher, Eberhard

2016-12-01

Corrosion fatigue (CF) tests were carried out on bulk glassy Zr52.5Cu17.9Al10Ni14.6Ti5 (Vitreloy 105) samples under load-controlled three-point bending conditions with a load ratio of R = 0.1 in 0.01 M Na2SO4 + 0.01 M NaCl electrolyte. During cyclic testing, the bar-shaped specimens were polarized in situ at constant potentials and the current was monitored. Three different anodic potentials within the interval between the pitting potential EP and the repassivation potential ER, and three different load amplitudes were applied. In some cases, in situ microscopic observations revealed the formation of black corrosion products in the vicinity of the crack tip during anodic polarization. Fractographic analysis revealed a clear distinction between two modes of crack growth characterized by smooth dissolution induced regions on the one hand and slim fast fracture areas on the other hand. Both alternating features contributed to a broad striated corrosion fatigue fracture surface. Moreover, further fatigue tests were carried out under free corrosion conditions yielding additional information on crack initiation and crack propagation period by means of the open circuit potential (OCP) changes. Thereby, a slight increase in OCP was detected after rupture of the passive layer due to bare metal exposed to the electrolyte. The electrochemical response increased continuously according to stable crack propagation until fracture occurred. Finally, the fracture surfaces of the corrosion fatigue samples were investigated by energy dispersive X-ray with the objective of analyzing the elemental distribution after anodic dissolution. Interestingly, anodic polarization at a near repassivation potential of -50 mV vs. SCE (Saturated Calomel Electrode, E = 0.241 V vs. SHE, Standard Hydrogen Electrode) led to favorable effects on the fatigue lifetime. In conclusion, all results are conflated to a corrosion fatigue model for bulk glassy Vitreloy 105 under anodic polarization in chloride-containing electrolyte and compared to the previously proposed stress corrosion mechanisms under similar conditions.

Prediction of Tidal Elevations and Barotropic Currents in the Gulf of Bone

NASA Astrophysics Data System (ADS)

Purnamasari, Rika; Ribal, Agustinus; Kusuma, Jeffry

2018-03-01

Tidal elevation and barotropic current predictions in the gulf of Bone have been carried out in this work based on a two-dimensional, depth-integrated Advanced Circulation (ADCIRC-2DDI) model for 2017. Eight tidal constituents which were obtained from FES2012 have been imposed along the open boundary conditions. However, even using these very high-resolution tidal constituents, the discrepancy between the model and the data from tide gauge is still very high. In order to overcome such issues, Green’s function approach has been applied which reduced the root-mean-square error (RMSE) significantly. Two different starting times are used for predictions, namely from 2015 and 2016. After improving the open boundary conditions, RMSE between observation and model decreased significantly. In fact, RMSEs for 2015 and 2016 decreased 75.30% and 88.65%, respectively. Furthermore, the prediction for tidal elevations as well as tidal current, which is barotropic current, is carried out. This prediction was compared with the prediction conducted by Geospatial Information Agency (GIA) of Indonesia and we found that our prediction is much better than one carried out by GIA. Finally, since there is no tidal current observation available in this area, we assume that, when tidal elevations have been fixed, then the tidal current will approach the actual current velocity.

Imaging ac losses in superconducting films via scanning Hall probe microscopy

NASA Astrophysics Data System (ADS)

Dinner, Rafael B.; Moler, Kathryn A.; Feldmann, D. Matthew; Beasley, M. R.

2007-04-01

Various local probes have been applied to understanding current flow through superconducting films, which are often surprisingly inhomogeneous. Here, we show that magnetic imaging allows quantitative reconstruction of both current density J and electric field E resolved in time and space in a film carrying subcritical ac current. Current reconstruction entails inversion of the Biot-Savart law, while electric fields are reconstructed using Faraday’s law. We describe the corresponding numerical procedures, largely adapting existing work to the case of a strip carrying ac current, but including other methods of obtaining the complete electric field from the inductive portion determined by Faraday’s law. We also delineate the physical requirements behind the mathematical transformations. We then apply the procedures to images of a strip of YBa2Cu3O7-δ carrying an ac current at 400Hz . Our scanning Hall probe microscope produces a time series of magnetic images of the strip with 1μm spatial resolution and 25μs time resolution. Combining the reconstructed J and E , we obtain a complete characterization including local critical current density, E-J curves, and power losses. This analysis has a range of applications from fundamental studies of vortex dynamics to practical coated conductor development.

Modeling and Simulation of Ablation-Controlled Plasmas

NASA Astrophysics Data System (ADS)

Kundrapu, Madhusudhan N.

Ablation and plasma formation in high energy laser target interactions and arc discharges are studied numerically. Each of the two processes is modeled separately due to the type of energy source and the resulting flow eld. Ablation of the target material and plasma formation are coupled to obtain evaporation rate, temperature distribution, velocity eld, and species concentration self-consistently. Laser ablation is studied in the perspective of directed energy applications, where beam size varies from few centimeters to tens of centimeters with energies extending up to 10 kW/cm2. Because of this high energy deposition, the evaporated material expands to supersonic speeds into the free space. Due to the large spot sizes and associated supersonic flow, one dimensional Euler equations are considered to be sufficient for modeling the plume. Instead, more emphasis was given to evaporation model, by introducing Knudsen layer kinetics at the plume target interface, and plasma shielding. The evaporation rate is validated with results from the experiments and simulations are carried out to nd the in fluence of laser beam frequency on evaporation rates. The evaporation model used in this work is found to be more accurate than the widely used model based on sonic speed assumption. The optimum beam wavelength for Al surfaces is found to be 850 nm. Attenuation of telemetry data by plasma is a concern for the testing of directed energy systems. Electrostatic approach for the mitigation of communication attenuation is analyzed to obtain the fluency limits up to which the approach can be implemented. It is found from sheath calculations that uninterrupted telemetry can be achieved through Al plasma for fluences below 4 J/cm2 at a background pressure of 1 atm, using a maximum bias voltage of 10 kV . Arc discharge ablation is modeled for the synthesis of nanoparticles. The electric arc generated between the electrodes, placed inside a Helium chamber, evaporates the catalyst-lled carbon anode to form a web of nanoparticles. Conservative form of Navier-Stokes equations along with energy equation and species transport are solved in cylindrical coordinates using SIMPLER algorithm. Current continuity in electric potential form is solved to obtain the potential distribution. Current is then calculated from the potential, and from axial current, magnetic eld is obtained using Ampere's law. Anode sublimation rate and current voltage characteristics are compared with experiments for arc currents varying from 10 to 100 A. Nanoparticle formation is estimated using homogeneous nucleation and surface diusion models. For an arc current of 60 A and inter-electrode gap of 4 mm with 68 Pa, the diameter of Nickel cluster is found to be 9.2 nm, which agrees with the upper limit of TEM measurements. The length of single walled nanotube is found to be 3.5 mum for this case. Parametric studies carried out by varying arc current, background pressure, and electrode gap showed moderate in uence on the growth rate. Hot chamber arc discharge method, proposed in this work, is found to be promising to maximize the growth of nanoparticles.

Multiscale Modeling of Novel Carbon Nanotube/Copper-Composite Material Used in Microelectronics

NASA Astrophysics Data System (ADS)

Awad, Ibrahim; Ladani, Leila

2016-06-01

Current carrying capacity is one of the elements that hinders further miniaturization of Copper (Cu) interconnects. Therefore, there is a need to propose new materials with higher ampacity (current carrying capacity) that have the potential to replace Cu. Experimental observations have shown that Carbon Nanotube (CNT)/Cu-composite material has a hundredfold ampacity of Cu, which makes it a good candidate to replace Cu. However, sufficient information about the mechanical behavior of the novel CNT/Cu-composite is not available. In the current paper, the CNT/Cu-composite is utilized to construct Through Silicon Via (TSV). The mechanical behavior, specifically the fatigue life, of the CNT/Cu-TSV is evaluated by applying a multiscale modeling approach. Molecular Dynamics (MD) simulations are conducted to evaluate the tensile strength and the coefficient of thermal expansion of CNTs. MD simulation is also used to determine the interface behavior between CNTs and Cu. MD simulation results are integrated into Finite Element analysis at the micro-level to estimate the fatigue life of the CNT/Cu-TSV. A comparison is made with base material; Cu. CNTs addition has redistributed the plastic deformation in Cu to occur at two different locations (Si/Cu interface and Cu/CNT interface) instead of only one location (Si/Cu interface) in the case of Cu-only-TSV. Thus, the maximum equivalent plastic strain has been alleviated in the CNT/Cu-TSV. Accordingly, CNT/Cu-TSV has shown a threefold increase in the fatigue life. This is a solid indication of the improvement in the fatigue life that is attributed to the addition of CNTs.

A highly sensitive electrochemical biosensor for catechol using conducting polymer reduced graphene oxide-metal oxide enzyme modified electrode.

PubMed

Sethuraman, V; Muthuraja, P; Anandha Raj, J; Manisankar, P

2016-10-15

The fabrication, characterization and analytical performances were investigated for a catechol biosensor, based on the PEDOT-rGO-Fe2O3-PPO composite modified glassy carbon (GC) electrode. The graphene oxide (GO) doped conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) was prepared through electrochemical polymerization by potential cycling. Reduction of PEDOT-GO was carried out by amperometric method. Fe2O3 nanoparticles were synthesized in ethanol by hydrothermal method. The mixture of Fe2O3, PPO and glutaraldehyde was casted on the PEDOT-rGO electrode. The surface morphology of the modified electrodes was studied by FE-SEM and AFM. Cyclic voltammetric studies of catechol on the enzyme modified electrode revealed higher reduction peak current. Determination of catechol was carried out successfully by Differential Pulse Voltammetry (DPV) technique. The fabricated biosensor investigated shows a maximum current response at pH 6.5. The catechol biosensor exhibited wide sensing linear range from 4×10(-8) to 6.20×10(-5)M, lower detection limit of 7×10(-9)M, current maxima (Imax) of 92.55µA and Michaelis-Menten (Km) constant of 30.48µM. The activation energy (Ea) of enzyme electrode is 35.93KJmol(-1) at 50°C. There is no interference from d-glucose and l-glutamic acid, ascorbic acid and o-nitrophenol. The PEDOT-rGO-Fe2O3-PPO biosensor was stable for at least 75 days when stored in a buffer at about 4°C. Copyright © 2015 Elsevier B.V. All rights reserved.

Probing dynamics and pinning of single vortices in superconductors at nanometer scales.

PubMed

Embon, L; Anahory, Y; Suhov, A; Halbertal, D; Cuppens, J; Yakovenko, A; Uri, A; Myasoedov, Y; Rappaport, M L; Huber, M E; Gurevich, A; Zeldov, E

2015-01-07

The dynamics of quantized magnetic vortices and their pinning by materials defects determine electromagnetic properties of superconductors, particularly their ability to carry non-dissipative currents. Despite recent advances in the understanding of the complex physics of vortex matter, the behavior of vortices driven by current through a multi-scale potential of the actual materials defects is still not well understood, mostly due to the scarcity of appropriate experimental tools capable of tracing vortex trajectories on nanometer scales. Using a novel scanning superconducting quantum interference microscope we report here an investigation of controlled dynamics of vortices in lead films with sub-Angstrom spatial resolution and unprecedented sensitivity. We measured, for the first time, the fundamental dependence of the elementary pinning force of multiple defects on the vortex displacement, revealing a far more complex behavior than has previously been recognized, including striking spring softening and broken-spring depinning, as well as spontaneous hysteretic switching between cellular vortex trajectories. Our results indicate the importance of thermal fluctuations even at 4.2 K and of the vital role of ripples in the pinning potential, giving new insights into the mechanisms of magnetic relaxation and electromagnetic response of superconductors.

Probing dynamics and pinning of single vortices in superconductors at nanometer scales

NASA Astrophysics Data System (ADS)

Embon, L.; Anahory, Y.; Suhov, A.; Halbertal, D.; Cuppens, J.; Yakovenko, A.; Uri, A.; Myasoedov, Y.; Rappaport, M. L.; Huber, M. E.; Gurevich, A.; Zeldov, E.

2015-01-01

The dynamics of quantized magnetic vortices and their pinning by materials defects determine electromagnetic properties of superconductors, particularly their ability to carry non-dissipative currents. Despite recent advances in the understanding of the complex physics of vortex matter, the behavior of vortices driven by current through a multi-scale potential of the actual materials defects is still not well understood, mostly due to the scarcity of appropriate experimental tools capable of tracing vortex trajectories on nanometer scales. Using a novel scanning superconducting quantum interference microscope we report here an investigation of controlled dynamics of vortices in lead films with sub-Angstrom spatial resolution and unprecedented sensitivity. We measured, for the first time, the fundamental dependence of the elementary pinning force of multiple defects on the vortex displacement, revealing a far more complex behavior than has previously been recognized, including striking spring softening and broken-spring depinning, as well as spontaneous hysteretic switching between cellular vortex trajectories. Our results indicate the importance of thermal fluctuations even at 4.2 K and of the vital role of ripples in the pinning potential, giving new insights into the mechanisms of magnetic relaxation and electromagnetic response of superconductors.

Electrical properties of the costo-uterine muscle of the guinea-pig.

PubMed Central

Parkington, H C

1983-01-01

The spontaneous electrical and mechanical activity of the costo-uterine muscle of the guinea-pig are described. The spontaneous electrical activity, recorded intracellularly, is similar to that observed previously in longitudinal myometrium of rat (Marshall, 1959) and ionic substitution suggests that, though calcium may be the predominant ion carrying the current during the upstroke of the action potential, some influence of sodium cannot be ruled out. During dioestrus, when circulating progesterone levels are high, there is an increase in the resting membrane potential and a decrease in the frequency of electrical and mechanical activity. There is a two-fold decrease in the space constant (lambda) during dioestrus. At this time the membrane time constant (tau m) is also decreased. The diameter and length of the smooth muscle cells are smaller during dioestrus. However, the differences in cell diameter do not explain all of the differences observed in lambda at this time and it is suggested that there may be an increase in the resistance to current flow between cells. It is concluded that high circulating progesterone may bring about quiescence of target smooth muscle in two ways: by stabilizing the cell membrane and by restricting the spread of activity. PMID:6683758

Potential effects of large-scale offshore tidal energy extraction in the Pentland Firth on North Sea biogeochemistry

NASA Astrophysics Data System (ADS)

van der Molen, Johan; Ruardij, Piet; Greenwood, Naomi

2016-04-01

Final results are presented of a model study to assess the potential wider area effects of large-scale tidal energy extraction in the Pentland Firth on the biogeochemistry. The coupled hydrodynamics-biogeochemistry model GETM-ERSEM-BFM was used in a shelf-wide application with a parameterisation of the effects of power extraction by tidal turbines on fluid momentum. Three secenario runs were carried out: a reference run without turbines, an 800 MW extraction run corresponding to current licenses, and an academic 8 GW extraction run. The changes simulated with the 800 MW extraction were negligible. The academic 8 GW extraction resulted in reductions in tidal elevations along the east coast of the UK that would be measurable (several cm.), and associated reductions in bed-shear stresses. These resulted in reductions in SPM concentrations, increased primary production, and increased biomass of zooplankton and benthic fauna. The effects were most pronounced in the shallow seas surrounding The Wash, with changes of up to 10%. These results indicate that, should tidal power generation substantially beyond the currently licensed amount be planned, either concentrated in one location or spread over multiple locations along the coast, further investigations are advisable.

Evaluation of Alkylamine Modified Pt Nanoparticles as Oxygen Reduction Reaction Electrocatalyst for Fuel Cells via Electrochemical Impedance Spectroscopy.

PubMed

Joshi, Prerna; Okada, Toshihiko; Miyabayashi, Keiko; Miyake, Mikio

2018-05-15

Organically (octyl amine, OA) surface modified electrocatalyst (OA-Pt/CB) was studied for its oxygen reduction reaction (ORR) activity via dc methods and its charge and mass transfer properties were studied via electrochemical impedance spectroscopy (EIS). Comparison with a commercial catalyst (TEC10V30E) with similar Pt content was also carried out. In EIS, both the catalysts showed a single time-constant with an emerging high-frequency semicircle of very small diameter which was fitted using suitable equivalent circuits. The organically modified catalyst showed lower charge-transfer resistance and hence, low polarization resistance in high potential region as compared to the commercial catalyst. The dominance of kinetic processes was observed at 0.925-1.000 V, whereas domination of diffusion based processes was observed at lower potential region for the organic catalyst. No effect due to the presence of carbon was observed in the EIS spectra. Using the hydrodynamic method, higher current penetration depth was obtained for the organically modified catalyst at 1600 rpm. Exchange current density and Tafel slopes for both the electrocatalysts were calculated from the polarization resistance obtained from EIS which was in correlation with the results obtained from dc methods.

EUROPA Multiple-Flyby Trajectory Design

NASA Technical Reports Server (NTRS)

Buffington, Brent; Campagnola, Stefano; Petropoulos, Anastassios

2012-01-01

As reinforced by the 2011 NRC Decadal Survey, Europa remains one of the most scientifically intriguing targets in planetary science due to its potential suitability for life. However, based on JEO cost estimates and current budgetary constraints, the Decadal Survey recommended-and later directed by NASA Headquarters-a more affordable pathway to Europa exploration be derived. In response, a flyby-only proof-of-concept trajectory has been developed to investigate Europa. The trajectory, enabled by employing a novel combination of new mission design techniques, successfully fulfills a set of Science Definition Team derived scientific objectives carried out by a notional payload including ice penetrating radar, topographic imaging, and short wavelength infrared observations, and ion neutral mass spectrometry in-situ measurements. The current baseline trajectory, referred to as 11-F5, consists of 34 Europa and 9 Ganymede flybys executed over the course of 2.4 years, reached a maximum inclination of 15 degrees, has a deterministic delta v of 157 m/s (post-PJR), and has a total ionizing dose of 2.06 Mrad (Si behind 100 mil Al, spherical shell). The 11-F5 trajectory and more generally speaking, flyby-only trajectories-exhibit a number of potential advantages over an Europa orbiter mission.

MoTe2, A novel anode material for sodium ion battery

NASA Astrophysics Data System (ADS)

Panda, Manas Ranjan; Anish Raj, K.; Bao, Qiaoliang; Mitra, Sagar

2018-04-01

2D layered transition metal dichalcogenides are considered as a potential anode for sodium-ion batteries due to their high specific capacity, structural stability and its well-developed two-dimensional layers. 2D layered structure Molybdenum ditelluride (MoTe2) provides a superior Na-ion storage properties in sodium ion battery due to its comparative more interlayer spacing (0.699 nm). In the current study MoTe2 polycrystalline powder sample has been prepared by solid state reaction process, the structural and morphological studies have been carried out by XRD, FE-SEM and EDS etc. XRD study revealsthe well crystalline structure of the material having hexagonal structure. FE-SEM and EDS studies depict the uniformflakes like structure of the material. When it is tested as sodium-ion battery anode by applying a potential window 0.1-2.5 V, the material demonstrates a high capacity and high power performances. The as prepared MoTe2 shows an initial discharge capacity of 376 mA h g-1 and a corresponding discharge capacity of 303 mA h g-1 after the 50th cycle at a current density of 500 mA g-1.

Spin splitting generated in a Y-shaped semiconductor nanostructure with a quantum point contact

NASA Astrophysics Data System (ADS)

Wójcik, P.; Adamowski, J.; Wołoszyn, M.; Spisak, B. J.

2015-07-01

We have studied the spin splitting of the current in the Y-shaped semiconductor nanostructure with a quantum point contact (QPC) in a perpendicular magnetic field. Our calculations show that the appropriate tuning of the QPC potential and the external magnetic field leads to an almost perfect separation of the spin-polarized currents: electrons with opposite spins flow out through different output branches. The spin splitting results from the joint effect of the QPC, the spin Zeeman splitting, and the electron transport through the edge states formed in the nanowire at the sufficiently high magnetic field. The Y-shaped nanostructure can be used to split the unpolarized current into two spin currents with opposite spins as well as to detect the flow of the spin current. We have found that the separation of the spin currents is only slightly affected by the Rashba spin-orbit coupling. The spin-splitter device is an analogue of the optical device—the birefractive crystal that splits the unpolarized light into two beams with perpendicular polarizations. In the magnetic-field range, in which the current is carried through the edges states, the spin splitting is robust against the spin-independent scattering. This feature opens up a possibility of the application of the Y-shaped nanostructure as a non-ballistic spin-splitter device in spintronics.

Incorporation of Ca and P on anodized titanium surface: Effect of high current density.

PubMed

Laurindo, Carlos A H; Torres, Ricardo D; Mali, Sachin A; Gilbert, Jeremy L; Soares, Paulo

2014-04-01

This study systematically evaluated the surface and corrosion characteristics of commercially pure titanium (grade 2) modified by plasma electrolytic oxidation (PEO) with high current density. The anodization process was carried out galvanostatically (constant current density) using a solution containing calcium glycerophosphate (0.02mol/L) and calcium acetate (0.15mol/L). The current densities applied were 400, 700, 1000 and 1200mA/cm(2) for a period of 15s. Composition, crystalline structure, morphology, roughness, wettability and "in-vitro" bioactivity test in SBF of the anodized layer were evaluated by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, profilometry and contact angle measurements. Corrosion properties were evaluated by open circuit potential, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. The results show that the TiO2 oxide layers present an increase of thickness, porosity, roughness, wettability, Ca/P ratio, and bioactivity, with the applied current density up to 1000mA/cm(2). Corrosion resistance also increases with applied current density. It is observed that for 1200mA/cm(2), there is a degradation of the oxide layer. In general, the results suggest that the anodized TiO2 layer with better properties is formed with an applied current of 1000mA/cm(2). Copyright © 2014 Elsevier B.V. All rights reserved.

Spin splitting generated in a Y-shaped semiconductor nanostructure with a quantum point contact

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wójcik, P., E-mail: pawel.wojcik@fis.agh.edu.pl; Adamowski, J., E-mail: janusz.adamowski@fis.agh.edu.pl; Wołoszyn, M.

2015-07-07

We have studied the spin splitting of the current in the Y-shaped semiconductor nanostructure with a quantum point contact (QPC) in a perpendicular magnetic field. Our calculations show that the appropriate tuning of the QPC potential and the external magnetic field leads to an almost perfect separation of the spin-polarized currents: electrons with opposite spins flow out through different output branches. The spin splitting results from the joint effect of the QPC, the spin Zeeman splitting, and the electron transport through the edge states formed in the nanowire at the sufficiently high magnetic field. The Y-shaped nanostructure can be usedmore » to split the unpolarized current into two spin currents with opposite spins as well as to detect the flow of the spin current. We have found that the separation of the spin currents is only slightly affected by the Rashba spin-orbit coupling. The spin-splitter device is an analogue of the optical device—the birefractive crystal that splits the unpolarized light into two beams with perpendicular polarizations. In the magnetic-field range, in which the current is carried through the edges states, the spin splitting is robust against the spin-independent scattering. This feature opens up a possibility of the application of the Y-shaped nanostructure as a non-ballistic spin-splitter device in spintronics.« less

Evaluation of floating-point sum or difference of products in carry-save domain

NASA Technical Reports Server (NTRS)

Wahab, A.; Erdogan, S.; Premkumar, A. B.

1992-01-01

An architecture to evaluate a 24-bit floating-point sum or difference of products using modified sequential carry-save multipliers with extensive pipelining is described. The basic building block of the architecture is a carry-save multiplier with built-in mantissa alignment for the summation during the multiplication cycles. A carry-save adder, capable of mantissa alignment, correctly positions products with the current carry-save sum. Carry propagation in individual multipliers is avoided and is only required once to produce the final result.

Octopamine increases the excitability of neurons in the snail feeding system by modulation of inward sodium current but not outward potassium currents.

PubMed

Vehovszky, Agnes; Szabó, Henriette; Elliott, Christopher J H

2005-12-06

Although octopamine has long been known to have major roles as both transmitter and modulator in arthropods, it has only recently been shown to be functionally important in molluscs, playing a role as a neurotransmitter in the feeding network of the snail Lymnaea stagnalis. The synaptic potentials cannot explain all the effects of octopamine-containing neurons on the feeding network, and here we test the hypothesis that octopamine is also a neuromodulator. The excitability of the B1 and B4 motoneurons in the buccal ganglia to depolarising current clamp pulses is significantly (P < < 0.05) increased by (10 microM) octopamine, whereas the B2 motoneuron becomes significantly less excitable. The ionic currents evoked by voltage steps were recorded using 2-electrode voltage clamp. The outward current of B1, B2 and B4 motoneurons had two components, a transient IA current and a sustained IK delayed-rectifier current, but neither was modulated by octopamine in any of these three buccal neurons. The fast inward current was eliminated in sodium-free saline and so is likely to be carried by sodium ions. 10 microM octopamine enhanced this current by 33 and 45% in the B1 and B4 motoneurons respectively (P < < 0.05), but a small reduction was seen in the B2 neuron. A Hodgkin-Huxley style simulation of the B1 motoneuron confirms that a 33% increase in the fast inward current by octopamine increases the excitability markedly. We conclude that octopamine is also a neuromodulator in snails, changing the excitability of the buccal neurons. This is supported by the close relationship from the voltage clamp data, through the quantitative simulation, to the action potential threshold, changing the properties of neurons in a rhythmic network. The increase in inward sodium current provides an explanation for the polycyclic modulation of the feeding system by the octopamine-containing interneurons, making feeding easier to initiate and making the feeding bursts more intense.

Climate-Induced Range Shifts and Possible Hybridisation Consequences in Insects

PubMed Central

Sánchez-Guillén, Rosa Ana; Muñoz, Jesús; Rodríguez-Tapia, Gerardo; Feria Arroyo, T. Patricia; Córdoba-Aguilar, Alex

2013-01-01

Many ectotherms have altered their geographic ranges in response to rising global temperatures. Current range shifts will likely increase the sympatry and hybridisation between recently diverged species. Here we predict future sympatric distributions and risk of hybridisation in seven Mediterranean ischnurid damselfly species (I. elegans, I. fountaineae, I. genei, I. graellsii, I. pumilio, I. saharensis and I. senegalensis). We used a maximum entropy modelling technique to predict future potential distribution under four different Global Circulation Models and a realistic emissions scenario of climate change. We carried out a comprehensive data compilation of reproductive isolation (habitat, temporal, sexual, mechanical and gametic) between the seven studied species. Combining the potential distribution and data of reproductive isolation at different instances (habitat, temporal, sexual, mechanical and gametic), we infer the risk of hybridisation in these insects. Our findings showed that all but I. graellsii will decrease in distributional extent and all species except I. senegalensis are predicted to have northern range shifts. Models of potential distribution predicted an increase of the likely overlapping ranges for 12 species combinations, out of a total of 42 combinations, 10 of which currently overlap. Moreover, the lack of complete reproductive isolation and the patterns of hybridisation detected between closely related ischnurids, could lead to local extinctions of native species if the hybrids or the introgressed colonising species become more successful. PMID:24260411

Acid production potentials of massive sulfide minerals and lead-zinc mine tailings: a medium-term study.

PubMed

Çelebi, Emin Ender; Öncel, Mehmet Salim; Kobya, Mehmet

2018-01-01

Weathering of sulfide minerals is a principal source of acid generation. To determine acid-forming potentials of sulfide-bearing materials, two basic approaches named static and kinetic tests are available. Static tests are short-term, and easily undertaken within a few days and in a laboratory. In contrast, kinetic tests are long-term procedures and mostly carried out on site. In this study, experiments were conducted over a medium-term period of 2 months, not as short as static tests and also not as long as kinetic tests. As a result, pH and electrical conductivity oscillations as a function of time, acid-forming potentials and elemental contents of synthetically prepared rainwater leachates of massive sulfides and sulfide-bearing lead-zinc tailings from abandoned and currently used deposition areas have been determined. Although the lowest final pH of 2.70 was obtained in massive pyrite leachate, massive chalcopyrite leachate showed the highest titrable acidity of 1.764 g H 2 SO 4 /L. On the other hand, a composite of currently deposited mine tailings showed no acidic characteristic with a final pH of 7.77. The composite abandoned mine tailing leachate had a final pH of 6.70, close to the final pH of massive galena and sphalerite leachates, and produced a slight titrable acidity of 0.130 g H 2 SO 4 /L.

Improving In Vivo Efficacy of Bioactive Molecules: An Overview of Potentially Antitumor Phytochemicals and Currently Available Lipid-Based Delivery Systems

PubMed Central

Torres, Carlos; Vázquez, Luis; Reglero, Guillermo; Fornari, Tiziana

2017-01-01

Cancer is among the leading causes of morbidity and mortality worldwide. Many of the chemotherapeutic agents used in cancer treatment exhibit cell toxicity and display teratogenic effect on nontumor cells. Therefore, the search for alternative compounds which are effective against tumor cells but reduce toxicity against nontumor ones is of great importance in the progress or development of cancer treatments. In this sense, scientific knowledge about relevant aspects of nutrition intimately involved in the development and progression of cancer progresses rapidly. Phytochemicals, considered as bioactive ingredients present in plant products, have shown promising effects as potential therapeutic/preventive agents on cancer in several in vitro and in vivo assays. However, despite their bioactive properties, phytochemicals are still not commonly used in clinical practice due to several reasons, mainly attributed to their poor bioavailability. In this sense, new formulation strategies are proposed as carriers to improve their bioefficacy, highlighting the use of lipid-based delivery systems. Here, we review the potential antitumoral activity of the bioactive compounds derived from plants and the current studies carried out in animal and human models. Furthermore, their association with lipids as a formulation strategy to enhance their efficacy in vivo is also reported. The development of high effective bioactive supplements for cancer treatment based on the improvement of their bioavailability goes through this association. PMID:28555156

Structure of the Magnetotail Current Sheet

NASA Technical Reports Server (NTRS)

Larson, Douglas J.; Kaufmann, Richard L.

1996-01-01

An orbit tracing technique was used to generate current sheets for three magnetotail models. Groups of ions were followed to calculate the resulting cross-tail current. Several groups then were combined to produce a current sheet. The goal is a model in which the ions and associated electrons carry the electric current distribution needed to generate the magnetic field B in which ion orbits were traced. The region -20 R(sub E) less than x less than - 14 R(sub E) in geocentric solar magnetospheric coordinates was studied. Emphasis was placed on identifying the categories of ion orbits which contribute most to the cross-tail current and on gaining physical insight into the manner by which the ions carry the observed current distribution. Ions that were trapped near z = 0, ions that magnetically mirrored throughout the current sheet, and ions that mirrored near the Earth all were needed. The current sheet structure was determined primarily by ion magnetization currents. Electrons of the observed energies carried relatively little cross-tail current in these quiet time current sheets. Distribution functions were generated and integrated to evaluate fluid parameters. An earlier model in which B depended only on z produced a consistent current sheet, but it did not provide a realistic representation of the Earth's middle magnetotail. In the present study, B changed substantially in the x and z directions but only weakly in the y direction within our region of interest. Plasmas with three characteristic particle energies were used with each of the magnetic field models. A plasma was found for each model in which the density, average energy, cross-tail current, and bulk flow velocity agreed well with satellite observations.

Structure of the Magnetotail Current Sheet

NASA Technical Reports Server (NTRS)

Larson, Douglas J.; Kaufmann, Richard L.

1996-01-01

An orbit tracing technique was used to generate current sheets for three magnetotail models. Groups of ions were followed to calculate the resulting cross-tail current. Several groups then were combined to produce a current sheet. The goal is a model in which the ions and associated electrons carry the electric current distribution needed to generate the magnetic field B in which ion orbits were traced. The region -20 R(E) less than x less than -14 R(E) in geocentric solar magnetospheric coordinates was studied. Emphasis was placed on identifying the categories of ion orbits which contribute most to the cross-tail current and on gaining physical insight into the manner by which the ions carry the observed current distribution. Ions that were trapped near z = 0, ions that magnetically mirrored throughout the current sheet, and ions that mirrored near the Earth all were needed. The current sheet structure was determined primarily by ion magnetization currents. Electrons of the observed energies carried relatively little cross-tail current in these quiet time current sheets. Distribution functions were generated and integrated to evaluate fluid parameters. An earlier model in which B depended only on z produced a consistent current sheet, but it did not provide a realistic representation of the Earth's middle magnetotail. In the present study, B changed substantially in the x and z directions but only weakly in the y direction within our region of interest. Plasmas with three characteristic particle energies were used with each of the magnetic field models. A plasma was found for each model in which the density, average energy, cross-tail current, and bulk flow velocity agreed well with satellite observations.

Iberiotoxin-sensitive and -insensitive BK currents in Purkinje neuron somata

PubMed Central

Benton, Mark D.; Lewis, Amanda H.; Bant, Jason S.

2013-01-01

Purkinje cells have specialized intrinsic ionic conductances that generate high-frequency action potentials. Disruptions of their Ca or Ca-activated K (KCa) currents correlate with altered firing patterns in vitro and impaired motor behavior in vivo. To examine the properties of somatic KCa currents, we recorded voltage-clamped KCa currents in Purkinje cell bodies isolated from postnatal day 17–21 mouse cerebellum. Currents were evoked by endogenous Ca influx with approximately physiological Ca buffering. Purkinje somata expressed voltage-activated, Cd-sensitive KCa currents with iberiotoxin (IBTX)-sensitive (>100 nS) and IBTX-insensitive (>75 nS) components. IBTX-sensitive currents activated and partially inactivated within milliseconds. Rapid, incomplete macroscopic inactivation was also evident during 50- or 100-Hz trains of 1-ms depolarizations. In contrast, IBTX-insensitive currents activated more slowly and did not inactivate. These currents were insensitive to the small- and intermediate-conductance KCa channel blockers apamin, scyllatoxin, UCL1684, bicuculline methiodide, and TRAM-34, but were largely blocked by 1 mM tetraethylammonium. The underlying channels had single-channel conductances of ∼150 pS, suggesting that the currents are carried by IBTX-resistant (β4-containing) large-conductance KCa (BK) channels. IBTX-insensitive currents were nevertheless increased by small-conductance KCa channel agonists EBIO, chlorzoxazone, and CyPPA. During trains of brief depolarizations, IBTX-insensitive currents flowed during interstep intervals, and the accumulation of interstep outward current was enhanced by EBIO. In current clamp, EBIO slowed spiking, especially during depolarizing current injections. The two components of BK current in Purkinje somata likely contribute differently to spike repolarization and firing rate. Moreover, augmentation of BK current may partially underlie the action of EBIO and chlorzoxazone to alleviate disrupted Purkinje cell firing associated with genetic ataxias. PMID:23446695

Effects of aluminium on electrical and mechanical properties of frog atrial muscle.

PubMed Central

Meiri, H.; Shimoni, Y.

1991-01-01

1. The effects of aluminium on membrane ionic currents were studied in single cardiac myocytes. Most of the work was done on frog atrial cells, but some experiments were also carried out on single cells isolated from rabbit ventricles and atria. 2. The effects of aluminium on the force of contraction of frog atrial trabeculae were also investigated. 3. Aluminium was prepared from AlCl3 as a stock 0.5 M solution which has a pH of 3.5. Before each experiment, this solution was added to the control solution, to give a final concentration of 20-100 micrograms ml-1 aluminium (0.75-3.75 mM AlCl3). The solutions were brought to a pH of 7.4 or 7.6. at which they consist of a mixture of amorphous aluminium hydroxides and a very small amount of soluble ionic aluminium complexes: free aluminium cations (less than 10 pM), aluminohydroxide anions (less than 8 microM). The addition of this suspension reduced the peak inward calcium currents in single rabbit atrial and ventricular cells and in frog atrial cells. In the latter, the peak current was reduced (at + 10 mV) to 45% of control (mean of 9 cells). This effect was reversible upon washout, and was obtained at all membrane potentials, with no shift of the calcium current voltage relationship along the voltage axis. 4. Aluminium also reduced the time-dependent potassium current IK. This reduction was observed at all membrane potentials. For example, at + 10 mV, the mean reduction of IK (n = 9) was to 69% of the control amplitude. This effect, which was very difficult to reverse, was not due to IK rundown.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2015425

Algebraic motion of vertically displacing plasmas

NASA Astrophysics Data System (ADS)

Pfefferlé, D.; Bhattacharjee, A.

2018-02-01

The vertical motion of a tokamak plasma is analytically modelled during its non-linear phase by a free-moving current-carrying rod inductively coupled to a set of fixed conducting wires or a cylindrical conducting shell. The solutions capture the leading term in a Taylor expansion of the Green's function for the interaction between the plasma column and the surrounding vacuum vessel. The plasma shape and profiles are assumed not to vary during the vertical drifting phase such that the plasma column behaves as a rigid body. In the limit of perfectly conducting structures, the plasma is prevented to come in contact with the wall due to steep effective potential barriers created by the induced Eddy currents. Resistivity in the wall allows the equilibrium point to drift towards the vessel on the slow timescale of flux penetration. The initial exponential motion of the plasma, understood as a resistive vertical instability, is succeeded by a non-linear "sinking" behaviour shown to be algebraic and decelerating. The acceleration of the plasma column often observed in experiments is thus concluded to originate from an early sharing of toroidal current between the core, the halo plasma, and the wall or from the thermal quench dynamics precipitating loss of plasma current.

A methodology to investigate the intrinsic effect of the pulsed electric current during the spark plasma sintering of electrically conductive powders

PubMed Central

Locci, Antonio Mario; Cincotti, Alberto; Todde, Sara; Orrù, Roberto; Cao, Giacomo

2010-01-01

A novel methodology is proposed for investigating the effect of the pulsed electric current during the spark plasma sintering (SPS) of electrically conductive powders without potential misinterpretation of experimental results. First, ensemble configurations (geometry, size and material of the powder sample, die, plunger and spacers) are identified where the electric current is forced to flow only through either the sample or the die, so that the sample is heated either through the Joule effect or by thermal conduction, respectively. These ensemble configurations are selected using a recently proposed mathematical model of an SPS apparatus, which, once suitably modified, makes it possible to carry out detailed electrical and thermal analysis. Next, SPS experiments are conducted using the ensemble configurations theoretically identified. Using aluminum powders as a case study, we find that the temporal profiles of sample shrinkage, which indicate densification behavior, as well as the final density of the sample are clearly different when the electric current flows only through the sample or through the die containing it, whereas the temperature cycle and mechanical load are the same in both cases. PMID:27877354

Assistive technologies along supply chains in health care and in the social services sector.

PubMed

Mayer, Peter; Hauer, Katharina; Schloffer, Evelyn; Leyrer, Barbara

2015-01-01

Health care systems in Austria and Slovenia are currently facing challenges due to scarce resources and demographic change which can be seen especially along the supply chains. The main objective of this paper is to present an option to improve the use of assistive technologies. An extensive literature research for the theoretic part as well as a qualitative survey for the empiric part focusing on short-term care were carried out. Results show that there is a lack of information and training on assistive technologies. As a consequence, their full potential cannot be exploited. Therefore a guideline for nursing consultations was developed. To conclude, both the literature research and the qualitative survey show that assistive technologies have high potentials to improve the supply chains in the health care and social services sector, but there is a lot of information and training on them needed.

Flammability testing of 22 conventional European pediculicides.

PubMed

Dörge, Dorian D; Kuhn, Thomas; Klimpel, Sven

2017-04-01

Lice have been parasitizing humans for at least 10,000 years. Since then, humans have tried to rid themselves of these unpleasant and potentially disease-carrying insects. Despite various plant extracts and chemical compounds being used to combat recurring infestations to this date, several lice populations have developed resistance to some of the abundantly used compounds. This resulted in the development of anti-louse products that physically kill the different lice stages. Today, a widely used group of delousing agents are dimethicones (polydimethylsiloxane PDMS) which function by suffocating the lice. However, many dimethicones and related products are highly flammable which makes them potentially dangerous for treatment. In the present study, we tested the flammability of 22 delousing agents in order to shed some light onto this currently unresolved problem in the product design of pediculicides. Thirteen products were easily ignitable, some even by distant contact with a sparkler.

Geosynchronous platform definition study. Volume 3: Geosynchronous mission characteristics

NASA Technical Reports Server (NTRS)

1973-01-01

The objectives of the study were to examine the nature of currently planned and new evolutionary geosynchronous programs, to analyze alternative ways of conducting missions, to establish concepts for new systems to support geosynchronous programs in an effective and economical manner, and to define the logistic support to carry out these programs. In order to meet these objectives, it was necessary to define and examine general geosynchronous mission characteristics and the potentially applicable electromagnetic spectrum characteristics. An organized compilation of these data is given with emphasis on the development and use of the data. Fundamental geosynchronous orbit time histories, mission profile characteristics, and delivery system characteristics are presented. In addition, electromagnetic spectrum utilization is discussed in terms of the usable frequency spectrum, the spectrum potentially available considering established frequency allocations, and the technology status as it affects the ability to operate within specific frequency bands.

A global synthesis of plant extinction rates in urban areas.

PubMed

Hahs, Amy K; McDonnell, Mark J; McCarthy, Michael A; Vesk, Peter A; Corlett, Richard T; Norton, Briony A; Clemants, Steven E; Duncan, Richard P; Thompson, Ken; Schwartz, Mark W; Williams, Nicholas S G

2009-11-01

Plant extinctions from urban areas are a growing threat to biodiversity worldwide. To minimize this threat, it is critical to understand what factors are influencing plant extinction rates. We compiled plant extinction rate data for 22 cities around the world. Two-thirds of the variation in plant extinction rates was explained by a combination of the city's historical development and the current proportion of native vegetation, with the former explaining the greatest variability. As a single variable, the amount of native vegetation remaining also influenced extinction rates, particularly in cities > 200 years old. Our study demonstrates that the legacies of landscape transformations by agrarian and urban development last for hundreds of years, and modern cities potentially carry a large extinction debt. This finding highlights the importance of preserving native vegetation in urban areas and the need for mitigation to minimize potential plant extinctions in the future.

A Comparison of Different Operating Systems for Femtosecond Lasers in Cataract Surgery.

PubMed

Wu, B M; Williams, G P; Tan, A; Mehta, J S

2015-01-01

The introduction of femtosecond lasers is potentially a major shift in the way we approach cataract surgery. The development of increasingly sophisticated intraocular lenses (IOLs), coupled with heightened patient expectation of high quality postsurgical visual outcomes, has generated the need for a more precise, highly reproducible and standardized method to carry out cataract operations. As femtosecond laser-assisted cataract surgery (FLACS) becomes more commonplace in surgical centers, further evaluation of the potential risks and benefits needs to be established, particularly in the medium/long term effects. Healthcare administrators will also have to weigh and balance out the financial costs of these lasers relative to the advantages they put forth. In this review, we provide an operational overview of three of five femtosecond laser platforms that are currently commercially available: the Catalys (USA), the Victus (USA), and the LDV Z8 (Switzerland).

CASA: tracking the past and plotting the future.

PubMed

Gallagher, M T; Smith, D J; Kirkman-Brown, J C

2018-05-29

The human semen sample carries a wealth of information of varying degrees of accessibility ranging from the traditional visual measures of count and motility to those that need a more computational approach, such as tracking the flagellar waveform. Although computer-aided sperm analysis (CASA) options are becoming more widespread, the gold standard for clinical semen analysis requires trained laboratory staff. In this review we characterise the key attitudes towards the use of CASA and set out areas in which CASA should, and should not, be used and improved. We provide an overview of the current CASA landscape, discussing clinical uses as well as potential areas for the clinical translation of existing research technologies. Finally, we discuss where we see potential for the future of CASA, and how the integration of mathematical modelling and new technologies, such as automated flagellar tracking, may open new doors in clinical semen analysis.

Therapy for immunoglobulin light chain amyloidosis: the new and the old.

PubMed

Gertz, Morie A; Lacy, Martha Q; Dispenzieri, Angela

2004-03-01

An accurate diagnosis of amyloidosis and its subtype classification are essential for disease prognostication and treatment. In primary amyloidosis, overall median survival is approximately 2 years and may be less in patients with cardiomyopathy. Current therapy for primary amyloidosis is suboptimal. Controlled studies suggest that treatment with melphalan and prednisone may provide marginal survival benefit. A more aggressive approach such as autologous hematopoietic stem cell transplantation may offer potential for long-term benefit. Although patients undergoing autologous hematopoietic stem cell transplantation are highly selected, response rates can approach 60%, and patients with amyloidosis who respond to treatment have potential for long-term survival. New treatment modalities that were shown to have antitumor activity in multiple myeloma (high-dose dexamethasone and thalidomide) may also be of therapeutic value in primary amyloidosis. Systemic chemotherapy would not be expected to have any beneficial effect on other forms of amyloid and carries significant risk.

The therapeutic potential of renin angiotensin aldosterone system (RAAS) in chronic pain: from preclinical studies to clinical trials.

PubMed

Bessaguet, Flavien; Magy, Laurent; Desmoulière, Alexis; Demiot, Claire

2016-01-01

The prevalence rate of chronic pain is 15% to 25% in adults while the therapeutic arsenal is still insufficient, especially in relieving neuropathic pain. Peripheral pain transmission is conducted by the small Aδ and C sensory nerve fibres. They express elements from the renin-angiotensin-aldosterone system (RAAS), a well-known blood pressure regulator. Recently, studies have demonstrated the role of angiotensin II, its derivatives and aldosterone in the modulation of pain perception, by interacting with receptors expressed by sensory nerve fibres or through the central nervous system. Here, we assess the effects of RAAS modulators in the conduction of pain with molecular, preclinical and clinical approaches, in normal or pathological conditions. Currently, some clinical studies have been carried out on the pain-relieving effect of RAAS modulators and suggest their potential in the management of chronic, inflammatory or neuropathic pain.

Quality parameters of mango and potential of non-destructive techniques for their measurement - a review.

PubMed

Jha, S N; Narsaiah, K; Sharma, A D; Singh, M; Bansal, S; Kumar, R

2010-01-01

The king of fruits "Mango" (Mangifera indica L.) is very nutritious and rich in carotenes. India produces about 50% of the total world's mango. Many researchers have reported the maturity indices and quality parameters for determination of harvesting time and eating quality. The methods currently used for determination of quality of mango are mostly based on the biochemical analysis, which leads to destruction of the fruits. Numerous works are being carried out to explore some non-destructive methods such as Near Infrared (NIR), Nuclear Magnetic Resonance (NMR), X-ray and Computed Tomography (CT), electronic nose, machine vision and ultrasound for quality determination of fruits. This paper deals with some recent work reported on quality parameters, harvesting and post-harvest treatments in relation to quality of mango fruits and reviews on some of the potential non-destructive techniques that can be explored for quality determination of mango cultivars.

Genetic variation in serotonin transporter function affects human fear expression indexed by fear-potentiated startle.

PubMed

Klumpers, Floris; Heitland, Ivo; Oosting, Ronald S; Kenemans, J Leon; Baas, Johanna M P

2012-02-01

The serotonin transporter (SERT) plays a crucial role in anxiety. Accordingly, variance in SERT functioning appears to constitute an important pathway to individual differences in anxiety. The current study tested the hypothesis that genetic variation in SERT function is associated with variability in the basic reflex physiology of defense. Healthy subjects (N=82) were presented with clearly instructed cues of shock threat and safety to induce robust anxiety reactions. Subjects carrying at least one short allele for the 5-HTTLPR polymorphism showed stronger fear-potentiated startle compared to long allele homozygotes. However, short allele carriers showed no deficit in the downregulation of fear after the offset of threat. These results suggest that natural variation in SERT function affects the magnitude of defensive reactions while not affecting the capacity for fear regulation. Copyright © 2011 Elsevier B.V. All rights reserved.

Slow, steady discharge regime for concentrated lead-acid cells with planar, cylindrical, and spherical electrodes

NASA Astrophysics Data System (ADS)

Yang, Yigang; Saslow, Wayne M.

1998-12-01

A recent theoretical study of slow, steady discharge for a lead-acid cell carrying current I, with planar electrodes, predicts a nonzero bulk charge distribution with an associated voltage profile within the electrolyte that is quadratic in space. A second theoretical study finds that the Ohmic voltage resistance R=ΔV/I across the electrolyte differs from the Joule heating resistance RJ=P/I2. The very different diffusion constants of the charge-carrying ions H+ and HSO4- is responsible for the quadratic voltage profile. The presence of changing chemical energies is responsible for the different resistances. In the present work we study this same chemical system for the cylindrical and spherical geometries, with Pb at inner radius a and PbO2 at outer radius b. For the cylindrical case, the voltage varies with radius as the sum of a logarithm and a quadratic. For the spherical case, the voltage varies with the radius as a sum of an inverse r and a quadratic. For both cases, the quadratic is the signature of a uniform nonzero bulk charge distribution. For both cases, R≠RJ. For large enough b/a, in both the spherical and cylindrical cases, we find that R<0; current flows from lower to higher electrical potential. This does not violate energy conservation when chemical as well as electrical energies are included.

What are the 'ideal' features of an adrenaline (epinephrine) auto-injector in the treatment of anaphylaxis?

PubMed

Frew, A J

2011-01-01

Anaphylaxis is a systemic allergic reaction that often involves respiratory symptoms and cardiovascular collapse, which are potentially life-threatening if not treated promptly with intramuscular adrenaline. Owing to the unpredictable nature of anaphylaxis and accidental exposure to allergens (such as peanuts and shellfish), patients should be prescribed intramuscular adrenaline auto-injectors and carry these with them at all times. Patients also need to be able to use their auto-injectors correctly while under high stress, when an anaphylactic attack occurs. Despite this, an alarming number of patients fail to carry their auto-injectors and many patients, carers of children with known anaphylaxis and healthcare professionals do not know how to use the device correctly, despite having had training. Currently available auto-injector devices have various limitations that may impede their use in the management of anaphylaxis. There is also a lack of validated assessment criteria and regulatory requirements for new devices. This review describes the different delivery systems used in currently available auto-injectors and discusses the key barriers to the use of adrenaline auto-injectors, with the goal of identifying the 'ideal' features/characteristics of such devices in the emergency treatment of anaphylaxis that will ensure ease of use, portability and accurate delivery of a life-saving drug. © 2010 John Wiley & Sons A/S.

Solid-State Multi-Sensor Array System for Real Time Imaging of Magnetic Fields and Ferrous Objects

NASA Astrophysics Data System (ADS)

Benitez, D.; Gaydecki, P.; Quek, S.; Torres, V.

2008-02-01

In this paper the development of a solid-state sensors based system for real-time imaging of magnetic fields and ferrous objects is described. The system comprises 1089 magneto inductive solid state sensors arranged in a 2D array matrix of 33×33 files and columns, equally spaced in order to cover an approximate area of 300 by 300 mm. The sensor array is located within a large current-carrying coil. Data is sampled from the sensors by several DSP controlling units and finally streamed to a host computer via a USB 2.0 interface and the image generated and displayed at a rate of 20 frames per minute. The development of the instrumentation has been complemented by extensive numerical modeling of field distribution patterns using boundary element methods. The system was originally intended for deployment in the non-destructive evaluation (NDE) of reinforced concrete. Nevertheless, the system is not only capable of producing real-time, live video images of the metal target embedded within any opaque medium, it also allows the real-time visualization and determination of the magnetic field distribution emitted by either permanent magnets or geometries carrying current. Although this system was initially developed for the NDE arena, it could also have many potential applications in many other fields, including medicine, security, manufacturing, quality assurance and design involving magnetic fields.

34 CFR 676.18 - Use of funds.

Code of Federal Regulations, 2010 CFR

2010-07-01

... end of the award year that it transferred to the FSEOG program from the FWS program. (c) Carry forward funds. (1) An institution may carry forward and expend in the next award year up to 10 percent of the... institution may spend its current year FSEOG allocation, it must spend any funds carried forward from the...

Development of a novel recessive genetic male sterility system for hybrid seed production in maize and other cross-pollinating crops.

PubMed

Wu, Yongzhong; Fox, Tim W; Trimnell, Mary R; Wang, Lijuan; Xu, Rui-Ji; Cigan, A Mark; Huffman, Gary A; Garnaat, Carl W; Hershey, Howard; Albertsen, Marc C

2016-03-01

We have developed a novel hybridization platform that utilizes nuclear male sterility to produce hybrids in maize and other cross-pollinating crops. A key component of this platform is a process termed Seed Production Technology (SPT). This process incorporates a transgenic SPT maintainer line capable of propagating nontransgenic nuclear male-sterile lines for use as female parents in hybrid production. The maize SPT maintainer line is a homozygous recessive male sterile transformed with a SPT construct containing (i) a complementary wild-type male fertility gene to restore fertility, (ii) an α-amylase gene to disrupt pollination and (iii) a seed colour marker gene. The sporophytic wild-type allele complements the recessive mutation, enabling the development of pollen grains, all of which carry the recessive allele but with only half carrying the SPT transgenes. Pollen grains with the SPT transgenes exhibit starch depletion resulting from expression of α-amylase and are unable to germinate. Pollen grains that do not carry the SPT transgenes are nontransgenic and are able to fertilize homozygous mutant plants, resulting in nontransgenic male-sterile progeny for use as female parents. Because transgenic SPT maintainer seeds express a red fluorescent protein, they can be detected and efficiently separated from seeds that do not contain the SPT transgenes by mechanical colour sorting. The SPT process has the potential to replace current approaches to pollen control in commercial maize hybrid seed production. It also has important applications for other cross-pollinating crops where it can unlock the potential for greater hybrid productivity through expanding the parental germplasm pool. © 2015 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogden, J.M.; Steinbugler, M.; Dennis, E.

For several years, researchers at Princeton University`s Center for Energy and Environmental Studies have carried out technical and economic assessments of hydrogen energy systems. Initially, we focussed on the long term potential of renewable hydrogen. More recently we have explored how a transition to renewable hydrogen might begin. The goal of our current work is to identify promising strategies leading from near term hydrogen markets and technologies toward eventual large scale use of renewable hydrogen as an energy carrier. Our approach has been to assess the entire hydrogen energy system from production through end-use considering technical performance, economics, infrastructure andmore » environmental issues. This work is part of the systems analysis activity of the DOE Hydrogen Program. In this paper we first summarize the results of three tasks which were completed during the past year under NREL Contract No. XR-11265-2: in Task 1, we carried out assessments of near term options for supplying hydrogen transportation fuel from natural gas; in Task 2, we assessed the feasibility of using the existing natural gas system with hydrogen and hydrogen blends; and in Task 3, we carried out a study of PEM fuel cells for residential cogeneration applications, a market which might have less stringent cost requirements than transportation. We then give preliminary results for two other tasks which are ongoing under DOE Contract No. DE-FG04-94AL85803: In Task 1 we are assessing the technical options for low cost small scale production of hydrogen from natural gas, considering (a) steam reforming, (b) partial oxidation and (c) autothermal reforming, and in Task 2 we are assessing potential markets for hydrogen in Southern California.« less

A Predictive Model for Submarine Canyon Type Based on the Relative Influence of Rivers, Waves and Tides.

NASA Astrophysics Data System (ADS)

Sumner, E.; Paull, C. K.

2017-12-01

In recent years progress has been achieved in directly measuring turbidity currents in submarine canyons and channels. It is useful to consider how representative these observations are of the diversity that potentially exists in the dynamics of turbidity currents among different canyons and channels. Firstly, we integrate sediment core, bathymetric and (in a limited number of cases) direct observations of turbidity current dynamics from 20 submarine canyons on the northern California Margin. We use this dataset to construct a diagram that explains canyon type, and thus turbidity current characteristics (grain-size carried, flow power, relative frequency of flows), based on the relative influence of rivers, waves and tides at the canyon head. This diagram enables prediction of canyon type and thus processes using three easily measurable characteristics: (i) distance of the canyon head from the shoreline; (ii) distance of the canyon head from the nearest river mouth; and (iii) local shelf width. Secondly, we test and refine the diagram using published data on submarine canyons from around the world. We also discuss the influence of outsized events such as earthquakes on submarine canyons. Finally, we demonstrate the location within the diagram of current monitoring studies and thus suggest where it might be fruitful to focus future monitoring efforts.

The Novel Antipsychotic Cariprazine (RGH-188): State-of-the-Art in the Treatment of Psychiatric Disorders.

PubMed

De Berardis, Domenico; Orsolini, Laura; Iasevoli, Felice; Prinzivalli, Emiliano; de Bartolomeis, Andrea; Serroni, Nicola; Mazza, Monica; Valchera, Alessandro; Fornaro, Michele; Vecchiotti, Roberta; Carano, Alessandro; Sepede, Gianna; Vellante, Federica; Matarazzo, Ilaria; Pompili, Maurizio; Perna, Giampaolo; Conti, Chiara; Segura-García, Cristina; Martinotti, Giovanni; Di Giannantonio, Massimo

2016-01-01

Cariprazine (RGH-188) is a novel antipsychotic drug that exerts partial agonism of dopamine D2/D3 receptors with preferential binding to D3 receptor, antagonism of 5HT2B receptors and partial agonism of 5HT1A. Currently, cariprazine is in late-stage clinical development (phase III clinical trials) in patients with schizophrenia (S) and in patients with bipolar disorder (BD), as well as an adjunctive treatment in patients with Major Depressive Disorder (MDD) and drug-resistant MDD. Cariprazine has completed phase III trials for the acute treatment of schizophrenia and bipolar mania, phase II trials for the bipolar depression and MDD whilst it is undergoing phase III trials as an adjunct to antidepressants. The present review aims at proving a comprehensive summary of the current evidence on the safety, tolerability and efficacy of cariprazine in the treatment of schizophrenia, BD (manic/mixed/ depressive episode) and MDD. A systematic search was conducted on PubMed/Medline/ Scopus and the database on Clinical Trials from inception until April 2015 by typing a set of specified keywords. Available evidence seems to support cariprazine efficacy in the treatment of cognitive and negative symptoms of schizophrenia. Preliminary findings suggest its antimanic activity whilst it is still under investigation its efficacy in the treatment of bipolar depression and MDD. Furthermore, the available data seems not to allow judgements about its antipsychotic potential in comparison with currently prescribed antipsychotics. Further studies should be carried out to better investigate its pharmacodynamic and clinical potential, particularly as alternative to current antipsychotic drugs.

Which level of competence and performance is expected? A survey among European employers of public health professionals.

PubMed

Vukovic, Dejana; Bjegovic-Mikanovic, Vesna; Otok, Robert; Czabanowska, Katarzyna; Nikolic, Zeljka; Laaser, Ulrich

2014-02-01

To explore largely unknown experience and expectations of European employers of public health professionals with regard to competences required to perform in the best way for the public health. A survey targeting employers in Europe was carried out September 2011–October 2012. The web-based questionnaire on public health competences and expected performance levels was returned by 63 organisations out of 109 contacted (57.8 %) as provided by Schools and Departments of Public Health (SDPH) in 30 European countries. The assessment of the current and desired levels of performance did not show significant differences between employer categories. However, current and desired levels across all employers differ significantly (p < 0.001), varying around a difference of one rank of a five-point scale. On the other hand, SDPH rank the exit qualifications of their graduates with one exception (presumed competences in preparedness for public health emergencies) higher than the current performance level as determined by employers, i.e. closer to their expectations. SDPH should reconsider priorities and question their estimate of exit qualifications in close contact with potential employers of their graduates.

Large pinning forces and matching effects in YBa2Cu3O7-δ thin films with Ba2Y(Nb/Ta)O6 nano-precipitates

PubMed Central

Opherden, Lars; Sieger, Max; Pahlke, Patrick; Hühne, Ruben; Schultz, Ludwig; Meledin, Alexander; Van Tendeloo, Gustaaf; Nast, Rainer; Holzapfel, Bernhard; Bianchetti, Marco; MacManus-Driscoll, Judith L.; Hänisch, Jens

2016-01-01

The addition of mixed double perovskite Ba2Y(Nb/Ta)O6 (BYNTO) to YBa2Cu3O7−δ (YBCO) thin films leads to a large improvement of the in-field current carrying capability. For low deposition rates, BYNTO grows as well-oriented, densely distributed nanocolumns. We achieved a pinning force density of 25 GN/m3 at 77 K at a matching field of 2.3 T, which is among the highest values reported for YBCO. The anisotropy of the critical current density shows a complex behavior whereby additional maxima are developed at field dependent angles. This is caused by a matching effect of the magnetic fields c-axis component. The exponent N of the current-voltage characteristics (inversely proportional to the creep rate S) allows the depinning mechanism to be determined. It changes from a double-kink excitation below the matching field to pinning-potential-determined creep above it. PMID:26887291

Laboratory evaluation of an OTT acoustic digital current meter and a SonTek Laboratory acoustic Doppler velocimeter

USGS Publications Warehouse

Vermeyen, T.B.; Oberg, Kevin A.; Jackson, Patrick Ryan

2009-01-01

Recently, an acoustic current meter known as the OTT * acoustic digital current meter (ADC) was introduced as an alternative instrument for stream gaging measurements. The Bureau of Reclamation and the U.S. Geological Survey collaborated on a side- by-side evaluation of the ADC and a SonTek/YSI acoustic Doppler velocimeter (ADV). Measurements were carried out in a laboratory flume to evaluate the performance characteristics of the ADC under a range of flow and boundary conditions. The flume contained a physical model of a mountain river with a diversion dam and variety of bed materials ranging from smooth mortar to a cobble bed. The instruments were installed on a trolley system that allowed them to be easily moved within the flume while maintaining a consistent probe orientation. More than 50 comparison measurements were made in an effort to verify the manufacturer’s performance specifications and to evaluate potential boundary disturbance for near-bed and vertical boundary measurements. Data and results from this evaluation are presented and discussed. 

Enhancement of bending strain tolerance and current carrying property of MgB2 based multifilamentary wires

NASA Astrophysics Data System (ADS)

Thomas, Syju; Varghese, Neson; Rahul, S.; Devadas, K. M.; Vinod, K.; Syamaprasad, U.

2012-12-01

The effect of bending strain on current carrying capacity of MgB2 multifilamentary wires was studied with 4, 8 and 16 multifilamentary wires. The critical current density (JC) of straight wires and bent wires with 5, 10, and 15 cm diameter was measured. Both annealed & bent and bent & annealed wires were used for measurement. The JC of annealed & bent wires were found to decrease with decrease in bent diameter and the rate of degradation of JC decreased with increasing number of filaments, while bent & annealed wires almost retained its JC at all diameters studied.

Physical mechanisms of timing jitter in photon detection by current-carrying superconducting nanowires

NASA Astrophysics Data System (ADS)

Sidorova, Mariia; Semenov, Alexej; Hübers, Heinz-Wilhelm; Charaev, Ilya; Kuzmin, Artem; Doerner, Steffen; Siegel, Michael

2017-11-01

We studied timing jitter in the appearance of photon counts in meandering nanowires with different fractional amount of bends. Intrinsic timing jitter, which is the probability density function of the random time delay between photon absorption in current-carrying superconducting nanowire and appearance of the normal domain, reveals two different underlying physical mechanisms. In the deterministic regime, which is realized at large photon energies and large currents, jitter is controlled by position-dependent detection threshold in straight parts of meanders. It decreases with the increase in the current. At small photon energies, jitter increases and its current dependence disappears. In this probabilistic regime jitter is controlled by Poisson process in that magnetic vortices jump randomly across the wire in areas adjacent to the bends.

Bioluminescent magnetic nanoparticles as potential imaging agents for mammalian spermatozoa.

PubMed

Vasquez, Erick S; Feugang, Jean M; Willard, Scott T; Ryan, Peter L; Walters, Keisha B

2016-03-17

Nanoparticles have emerged as key materials for developing applications in nanomedicine, nanobiotechnology, bioimaging and theranostics. Existing bioimaging technologies include bioluminescent resonance energy transfer-conjugated quantum dots (BRET-QDs). Despite the current use of BRET-QDs for bioimaging, there are strong concerns about QD nanocomposites containing cadmium which exhibits potential cellular toxicity. In this study, bioluminescent composites comprised of magnetic nanoparticles and firefly luciferase (Photinus pyralis) are examined as potential light-emitting agents for imaging, detection, and tracking mammalian spermatozoa. Characterization was carried out using infrared spectroscopy, TEM and cryo-TEM imaging, and ζ-potential measurements to demonstrate the successful preparation of these nanocomposites. Binding interactions between the synthesized nanoparticles and spermatozoon were characterized using confocal and atomic/magnetic force microscopy. Bioluminescence imaging and UV-visible-NIR microscopy results showed light emission from sperm samples incubated with the firefly luciferase-modified nanoparticles. Therefore, these newly synthesized luciferase-modified magnetic nanoparticles show promise as substitutes for QD labeling, and can potentially also be used for in vivo manipulation and tracking, as well as MRI techniques. These preliminary data indicate that luciferase-magnetic nanoparticle composites can potentially be used for spermatozoa detection and imaging. Their magnetic properties add additional functionality to allow for manipulation, sorting, or tracking of cells using magnetic techniques.

A modeling study on the hydrodynamics of a coastal embayment occupied by mussel farms (Ria de Ares-Betanzos, NW Iberian Peninsula)

NASA Astrophysics Data System (ADS)

Duarte, Pedro; Alvarez-Salgado, Xosé Antón; Fernández-Reiriz, Maria José; Piedracoba, Silvia; Labarta, Uxío

2014-06-01

The present study suggests that both under upwelling and downwelling winds, the residual circulation of Ria de Ares-Betanzos remains positive with a strong influence from river discharge and a positive feedback from wind, unlike what is generally accepted for Galician rias. Furthermore, mussel cultivation areas may reduce residual velocities by almost 40%, suggesting their potential feedbacks on food replenishment for cultivated mussels. The Ria de Ares-Betanzos is a partially stratified estuary in the NW Iberian upwelling system where blue mussels are extensively cultured on hanging ropes. This type of culture depends to a large extent on water circulation and residence times, since mussels feed on suspended particles. Therefore, understanding the role of tides, continental runoff, and winds on the circulation of this embayment has important practical applications. Furthermore, previous works have emphasized the potential importance of aquaculture leases on water circulation within coastal ecosystems, with potential negative feedbacks on production carrying capacity. Here we implemented and validated a 3D hydrodynamic numerical model for the Ria de Ares-Betanzos to (i) evaluate the relative importance of the forcing agents on the circulation within the ria and (ii) estimate the importance of culture leases on circulation patterns at the scale of the mussel farms from model simulations. The model was successfully validated with empirical current velocity data collected during July and October 2007 using an assortment of efficiency criteria. Model simulations were carried out to isolate the effects of wind and river flows on circulation patterns.

The calcium current of Helix neuron

PubMed Central

1978-01-01

Calcium current, Ica, was studied in isolated nerve cell bodies of Helix aspersa after suppression of Na+ and K+ currents. The suction pipette method described in the preceding paper was used. Ica rises to a peak value and then subsides exponentially and has a null potential of 150 mV or more and a relationship with [Ca2+]o that is hyperbolic over a small range of [Ca2+]o's. When [Ca2+]i is increased, Ica is reduced disproportionately, but the effect is not hyperbolic. Ica is blocked by extracellular Ni2+, La3+, Cd2+, and Co2+ and is greater when Ba2+ and Sr2+ carry the current. Saturation and blockage are described by a Langmuir adsorption relationship similar to that found in Balanus. Thus, the calcium conductance probably contains a site which binds the ions referred to. The site also appears to be voltage-dependent. Activation and inactivation of Ica are described by first order kinetics, and there is evidence that the processes are coupled. For example, inactivation is delayed slightly in its onset and tau inactivation depends upon the method of study. However, the currents are described equally well by either a noncoupled Hodgkin-Huxley mh scheme or a coupled reaction. Facilitation of Ica by prepulses was not observed. For times up to 50 ms, currents even at small depolarizations were accounted for by suitable adjustment of the activation and inactivation rate constants. PMID:660160

Investigation on Microstructure and Mechanical Properties of Continuous and Pulsed Current Gas Tungsten Arc Welded alloy 600

NASA Astrophysics Data System (ADS)

Srikanth, A.; Manikandan, M.

2018-02-01

The present study investigates the microstructure and mechanical properties of joints fabricated by Continuous and pulsed current gas tungsten arc welded alloy 600. Welding was done by autogenous mode. The macro examination was carried out to evaluate the welding defects in the weld joints. Optical and Scanning Electron Microscope (SEM) were performed to assess the microstructural changes in the fusion zone. Energy Dispersive Spectroscopy (EDS) analysis was carried to evaluate the microsegregation of alloying elements in the fusion zone. The tensile test was conducted to assess the strength of the weld joints. The results show that no welding defects were observed in the fusion zones of Continuous and Pulsed current Gas Tungsten Arc Welding. The refined microstructure was found in the pulsed current compared to continuous current mode. Microsegregation was not noticed in the weld grain boundary of continuous and pulsed current mode. The pulsed current shows improved mechanical properties compared to the continuous current mode.

Carry-over of dietary organochlorine pesticides, PCDD/Fs, PCBs, and brominated flame retardants to Atlantic salmon (Salmo salar L.) fillets.

PubMed

Berntssen, Marc H G; Maage, A; Julshamn, K; Oeye, B E; Lundebye, A-K

2011-03-01

Information on carry-over of contaminants from feed to animal food products is essential for appropriate human risk assessment of feed contaminants. The carry-over of potentially hazardous persistent organic pollutants (POPs) from feed to fillet was assessed in consumption sized Atlantic salmon (Salmo salar). Relative carry-over (defined as the fraction of a certain dietary POP retained in the fillet) was assessed in a controlled feeding trial, which provided fillet retention of dietary organochlorine pesticides (OCPs), dioxins (PCDD/Fs), polychlorinated biphenyls (PCBs), and brominated flame retardants (BFRs). Highest retention was found for OCPs, BFRs and PCBs (31-58%), and the lowest retentions were observed for PCDD/Fs congeners (10-34%). National monitoring data on commercial fish feed and farmed Atlantic salmon on the Norwegian market were used to provide commercially relevant feed-to-fillet transfer factors (calculated as fillet POP level divided by feed POP level), which ranged from 0.4 to 0.5, which is a factor 5-10 times higher than reported for terrestrial meat products. For the OCP with one of the highest relative carry-over, toxaphene, uptake and elimination kinetics were established. Model simulations that are based on the uptake and elimination kinetics gave predicted levels that were in agreement with the measured values. Application of the model to the current EU upper limit for toxaphene in feed (50 μg kg(-1)) gave maximum fillet levels of 22 μg kg(-1), which exceeds the estimated permissible level (21 μg kg(-1)) for toxaphene in fish food samples in Norway. Copyright © 2011 Elsevier Ltd. All rights reserved.

[Design of a plan for patient safety in pediatric surgery service].

PubMed

Paredes Esteban, R M; Castillo Fernández, A L; Miñarro del Moral, R; Garrido Pérez, J I; Granero Cendón, R; Gómez Beltrán, O; Berenguer Garcia, M J; Tejedor Fernández, M

2014-10-01

Patient safety is a key priority in quality management for healthcare services providers. Every patient is entitled to receive safe and effective healthcare. The aim of this study was to design a patient safety plan for a Paediatric Surgery Department. We carried out a literature review and we established a work group that included healthcare professionals from the Paediatric Surgery Department and the Quality and Medical Records Department. The group identified potential adverse events, failures and causes and established a rating using Failure Mode Effects Analysis. Potential risks were mapped out and a plan was designed establishing actions to reduce risks. We designated leaders to ensure the effective implementation of the plan. A total of 58 adverse events were identified in the Paediatric Surgery Department. We detected 128 failures that were produced by 211 different causes. The group developed a proposal with 424 specific measures to carry out preventive and/or remedial actions that were then narrowed down to 322. The group designed a plan to apply the programme, which is currently being implemented. The methodology used enabled obtaining key information for improvement of patient safety and developing preventive and/or remedial actions. These measures are applicable in practice, as they were designed using proposals and agreements with professionals that take active part in the care of children with surgical conditions.

Controlling Ionic Transport for Device Design in Synthetic Nanopores

NASA Astrophysics Data System (ADS)

Kalman, Eric Boyd

Polymer nanopores present a number of behaviors not seen in microscale systems, such as ion current rectification, ionic selectivity, size exclusion and potential dependent ion concentrations in and near the pore. The existence of these effects stems from the small size of nanopores with respect to the characteristic length scales of surface interactions at the interface between the nanopore surface and the solution within it. The large surface-to-volume ratio due to the nanoscale geometry of a nanopore, as well as similarity in scale between geometry and interaction demands the solution interact with the nanopore walls. As surfaces in solution almost always carry residual charge, these surface forces are primarily the electrostatic interactions between the charge groups on the pore surface and the ions in solution. These interactions may be used by the experimentalist to control ionic transport through synthetic nanopores, and use them as a template for the construction of devices. In this research, we present our work on creating a number of ionic analogs to seminal electronic devices, specifically diodes, and transistors, by controlling ionic transport through the electrostatic interactions between a single synthetic nanopore and ions. Control is achieved by "doping" the effective charge carrier concentration in specific regions of the nanopore through manipulation of the pore's surface charge. This manipulation occurs through two mechanisms: chemical modification of the surface charge and electrostatic manipulation of the local internal nanopore potential using a gate electrode. Additionally, the innate selectivity of the charged nanopores walls allows for the separation of charges in solution. This well-known effect, which spawns measureable quantities, the streaming potential and current, has been used to create nanoscale water desalination membranes. We attempt to create a device using membranes with large nanopore densities for the desalination of water which should theoretically outperform currently available devices, as through our previous work we have developed techniques allowing for transport manipulation not current accessible in traditional membrane motifs.

Hydrogeophysical investigations at Hidden Dam, Raymond, California

USGS Publications Warehouse

Minsley, Burke J.; Burton, Bethany L.; Ikard, Scott; Powers, Michael H.

2011-01-01

Self-potential and direct current resistivity surveys are carried out at the Hidden Dam site in Raymond, California to assess present-day seepage patterns and better understand the hydrogeologic mechanisms that likely influence seepage. Numerical modeling is utilized in conjunction with the geophysical measurements to predict variably-saturated flow through typical two-dimensional dam cross-sections as a function of reservoir elevation. Several different flow scenarios are investigated based on the known hydrogeology, as well as information about typical subsurface structures gained from the resistivity survey. The flow models are also used to simulate the bulk electrical resistivity in the subsurface under varying saturation conditions, as well as the self-potential response using petrophysical relationships and electrokinetic coupling equations.The self-potential survey consists of 512 measurements on the downstream area of the dam, and corroborates known seepage areas on the northwest side of the dam. Two direct-current resistivity profiles, each approximately 2,500 ft (762 m) long, indicate a broad sediment channel under the northwest side of the dam, which may be a significant seepage pathway through the foundation. A focusing of seepage in low-topography areas downstream of the dam is confirmed from the numerical flow simulations, which is also consistent with past observations. Little evidence of seepage is identified from the self-potential data on the southeast side of the dam, also consistent with historical records, though one possible area of focused seepage is identified near the outlet works. Integration of the geophysical surveys, numerical modeling, and observation well data provides a framework for better understanding seepage at the site through a combined hydrogeophysical approach.

Coherent current-carrying filaments during nonlinear reconnecting ELMs and VDEs

NASA Astrophysics Data System (ADS)

Ebrahimi, Fatima

2017-10-01

We have examined plasmoid-mediated reconnection in a spherical tokamak using global nonlinear three-dimensional resistive MHD simulations with NIMROD. We have shown that physical current sheets/layers develop near the edge as a peeling component of ELMs or during vertical displacement events (associated with the scrape-off layer currents - halo currents), can become unstable to nonaxisymmetric 3-D current-sheet instabilities (peeling- or tearing-like) and nonlinearly form edge coherent current-carrying filaments. Time-evolving edge current sheets with reconnecting nature in NSTX and NSTX-U configurations are identified. In the case of peeling-like edge localized modes, the longstanding problem of quasiperiodic ELMs cycles is explained through the relaxation of edge current via direct numerical calculations of reconnecting emf terms. For the VDEs during disruption, we show that as the plasma is vertically displaced, edge halo current sheet becomes MHD unstable and forms coherent edge current filament structures, which would eventually bleed into the walls. Our model explains some essential asymmetric physics relevant to the experimental observations. Supported by DOE Grants DE-SC0010565, DE-AC02-09CH11466.

The development of a natural language interface to a geographical information system

NASA Technical Reports Server (NTRS)

Toledo, Sue Walker; Davis, Bruce

1993-01-01

This paper will discuss a two and a half year long project undertaken to develop an English-language interface for the geographical information system GRASS. The work was carried out for NASA by a small business, Netrologic, based in San Diego, California, under Phase 1 and 2 Small Business Innovative Research contracts. We consider here the potential value of this system whose current functionality addresses numerical, categorical and boolean raster layers and includes the display of point sets defined by constraints on one or more layers, answers yes/no and numerical questions, and creates statistical reports. It also handles complex queries and lexical ambiguities, and allows temporarily switching to UNIX or GRASS.

An electrochemical approach to development of a method for accele strength evaluation of hard tissue replacement materials

NASA Astrophysics Data System (ADS)

Lee, Byung Jun; Kim, Min Gun

2003-04-01

To develop a method of accelerating the strength evaluation of hard tissue replacement materials (Ti-6Al-4V alloy) with an electrochemical approach in the short term, corrosion tests were carried out on Ti-6Al-4V alloy) by means of applying a uniform current to a simulated physiological environment and the potental difference was scanned to check the variations in the resistance of the specimens. As a result, the corrosion behavior was monitored by scanning the potential difference and an empirical formula for controlling the corrosion behavior of the Ti-6Al-4V alloy in the simulated physiological environment was proposed.

Maximizing JWST Science for Dusty White Dwarfs

NASA Astrophysics Data System (ADS)

Farihi, Jay; Dennihy, Erik; Gentile Fusillo, Nicola; Debes, John; Gaensicke, Boris

2018-05-01

We propose a small program to increase the number of dusty white dwarfs that can be studied in detail by the James Webb Space Telescope. Currently, there are 8 systems for which MIRI MRS spectroscopy can be carried out in less than a few hours per target, and here we propose to double this number. Using cross-correlation of AllWISE photometry with Southern Hemisphere surveys such as Edinburgh-Cape and ATLAS, we have selected the strongest 22 potential dusty white dwarf candidates. We propose to use warm IRAC imaging photometry as the ultimate discriminant between dust and common photometric contaminants. This program has immediate legacy value via detailed mineralogical studies of debris disks using JWST.

Screening of redox couples and electrode materials

NASA Technical Reports Server (NTRS)

Giner, J.; Swette, L.; Cahill, K.

1976-01-01

Electrochemical parameters of selected redox couples that might be potentially promising for application in bulk energy storage systems were investigated. This was carried out in two phases: a broad investigation of the basic characteristics and behavior of various redox couples, followed by a more limited investigation of their electrochemical performance in a redox flow reactor configuration. In the first phase of the program, eight redox couples were evaluated under a variety of conditions in terms of their exchange current densities as measured by the rotating disk electrode procedure. The second phase of the program involved the testing of four couples in a redox reactor under flow conditions with a varity of electrode materials and structures.

Genomes, free radicals and plant cell invasion: recent developments in plant pathogenic fungi.

PubMed

Egan, Martin J; Talbot, Nicholas J

2008-08-01

This review describes current advances in our understanding of fungal-plant interactions. The widespread application of whole genome sequencing to a diverse range of fungal species has allowed new insight into the evolution of fungal pathogenesis and the definition of the gene inventories associated with important plant pathogens. This has also led to functional genomic approaches to carry out large-scale gene functional analysis. There has also been significant progress in understanding appressorium-mediated plant infection by fungi and its underlying genetic basis. The nature of biotrophic proliferation of fungal pathogens in host tissue has recently revealed new potential mechanisms for cell-to-cell movement by invading pathogens.

Indicators for the use of robotic labs in basic biomedical research: a literature analysis

PubMed Central

2017-01-01

Robotic labs, in which experiments are carried out entirely by robots, have the potential to provide a reproducible and transparent foundation for performing basic biomedical laboratory experiments. In this article, we investigate whether these labs could be applicable in current experimental practice. We do this by text mining 1,628 papers for occurrences of methods that are supported by commercial robotic labs. Using two different concept recognition tools, we find that 86%–89% of the papers have at least one of these methods. This and our other results provide indications that robotic labs can serve as the foundation for performing many lab-based experiments. PMID:29134146

High efficiency yellow organic light-emitting diodes with optimized barrier layers

NASA Astrophysics Data System (ADS)

Mu, Ye; Zhang, Shiming; Yue, Shouzhen; Wu, Qingyang; Zhao, Yi

2015-12-01

High efficiency Iridium (III) bis (4-phenylthieno [3,2-c] pyridinato-N,C2‧) acetylacetonate (PO-01) based yellow organic light-emitting devices are fabricated by employing multiple emission layers. The efficiency of the device using 4,4‧,4″-tris(N-carbazolyl) triphenylamine (TCTA) as potential barrier layer (PBL) outperforms those devices based on other PBLs and detailed analysis is carried out to reveal the mechanisms. A forward-viewing current efficiency (CE) of 65.21 cd/A, which corresponds to a maximum total CE of 110.85 cd/A is achieved at 335.8 cd/m2 in the optimized device without any outcoupling enhancement structures.

Guided magnonic Michelson interferometer

PubMed Central

Ahmed, Muhammad H.; Jeske, Jan; Greentree, Andrew D.

2017-01-01

Magnonics is an emerging field with potential applications in classical and quantum information processing. Freely propagating magnons in two-dimensional media are subject to dispersion, which limits their effective range and utility as information carriers. We show the design of a confining magnonic waveguide created by two surface current carrying wires placed above a spin-sheet, which can be used as a primitive for reconfigurable magnonic circuitry. We theoretically demonstrate the ability of such guides to counter the transverse dispersion of the magnon in a spin-sheet, thus extending the range of the magnon. A design of a magnonic directional coupler and controllable Michelson interferometer is shown, demonstrating its utility for information processing tasks. PMID:28134271

Detection of Alpha Particles and Low Energy Gamma Rays by Thermo-Bonded Micromegas in Xenon Gas

NASA Astrophysics Data System (ADS)

Wei, Yuehuan; Guan, Liang; Zhang, Zhiyong; Lin, Qing; Wang, Xiaolian; Ni, Kaixuan; Zhao, Tianchi

2013-08-01

Micromegas is a type of micro-pattern gaseous detector currently under R&D for applications in rare event search experiments. Here we report the performance of a Micromegas structure constructed with a micromesh thermo-bonded to a readout plane, motivated by its potential application in two-phase xenon detectors for dark matter and neutrinoless double beta decay experiments. The study is carried out in pure xenon at room temperature. Measurements with alpha particles from the Americium-241 source showed that gas gains larger than 200 can be obtained at xenon pressure up to 3 atm. Gamma rays down to 8 keV were observed with such a device.

Conductance of carbon based macro-molecular structures

NASA Astrophysics Data System (ADS)

Stafström, S.; Hansson, A.; Paulsson, M.

2000-11-01

Electron transport through metallic nanotubes and stacks of wide bandgap polyaromatic hydrocarbons (PAH) are studied theoretically using the Landauer formalism. These two systems constitute examples of different types of carbon based nanostructured materials of potential use in molecular electronics. The studies are carried out for structures with finite length that bridge two contact pads. In the case of perfect metallic nanotubes, the current is observed to increase stepwise with the applied voltage and the resistance is independent on the length of the tube. In the PAH stacks, the off resonance tunneling conductance decreases exponentially with the number of molecules in the stack and shows a near linear increase with the number of carbon atoms in each molecule.

Grazing incidence metal optics for the Berkeley Extreme Ultraviolet Explorer satellite - A progress report

NASA Technical Reports Server (NTRS)

Finley, D.; Malina, R. F.; Bowyer, S.

1985-01-01

The four flight Wolter-Schwarzschild mirrors currently under fabrication for the Extreme Ultraviolet Explorer (EUVE) satellite are described. The principal figuring operation of these grazing incidence metal mirrors (gold over nickel on an aluminum substrate) is carried out by diamond turning at the Lawrence Livermore National Laboratories. Turning has been accomplished and optical testing results analyzed for three of the mirrors. As-turned values of 1.7 arc sec full width at half maximum (FWHM) and half energy width (HEW) of 5 arc seconds in the visible have been achieved. These results illustrate the great potential of precision fabrication technology for the production of large grazing incidence optics.

In situ stress and fracture permeability along the Stillwater fault zone, Dixie Valley Nevada

USGS Publications Warehouse

Hickman, S.H.; Barton, C.A.; Zoback, M.D.; Morin, R.; Sass, J.; Benoit, R.

1997-01-01

Borehole televiewer and hydrologic logging and hydraulic fracturing stress measurements were carried out in a 2.7-km-deep geothermal production well (73B-7) drilled into the Stillwater fault zone. Precision temperature and spinner flowmeter logs were also acquired in well 73B-7, with and without simultaneously injecting water into the well. Localized perturbations to well-bore temperature and flow were used to identify hydraulically conductive fractures. Comparison of these data with fracture orientations from the televiewer log indicates that permeable fractures within and adjacent to the Stillwater fault zone are critically stressed, potentially active shear planes in the current west-northwest extensional stress regime at Dixie Valley.

Parameters assessment of the inductively-coupled circuit for wireless power transfer

NASA Astrophysics Data System (ADS)

Isaev, Yu N.; Vasileva, O. V.; Budko, A. A.; Lefebvre, S.

2017-02-01

In this paper, a wireless power transfer model through the example of inductively-coupled coils of irregular shape in software package COMSOL Multiphysics is studied. Circuit parameters, such as inductance, coil resistance and self-capacitance were defined through electromagnetic energy by the finite-element method. The study was carried out according to Helmholtz equation. Spatial distribution of current per unit depending on frequency and the coupling coefficient for analysis of resonant frequency and spatial distribution of the vector magnetic potential at different distances between coils were presented. The resulting algorithm allows simulating the wireless power transfer between the inductively coupled coils of irregular shape with the assessment of the optimal parameters.

Improving NASA's technology for space science

NASA Technical Reports Server (NTRS)

1993-01-01

The continued advance of the nation's space program is directly dependent upon the development and use of new technology. Technology is the foundation for every aspect of space missions and ground operations. The improvements in technology that will enable future advances are not only in device and system performance, but also in permitting missions to be carried out more rapidly and at lower cost. Although more can be done with current technology, NASA's recent call for new and innovative approaches should not be answered by employing only today's technologies; new technologies with revolutionary potential should be sought. The study reported here was performed to identify means to enhance the development of technologies for the space sciences and applications.

Malaria Molecular Epidemiology: Lessons from the International Centers of Excellence for Malaria Research Network.

PubMed

Escalante, Ananias A; Ferreira, Marcelo U; Vinetz, Joseph M; Volkman, Sarah K; Cui, Liwang; Gamboa, Dionicia; Krogstad, Donald J; Barry, Alyssa E; Carlton, Jane M; van Eijk, Anna Maria; Pradhan, Khageswar; Mueller, Ivo; Greenhouse, Bryan; Pacheco, M Andreina; Vallejo, Andres F; Herrera, Socrates; Felger, Ingrid

2015-09-01

Molecular epidemiology leverages genetic information to study the risk factors that affect the frequency and distribution of malaria cases. This article describes molecular epidemiologic investigations currently being carried out by the International Centers of Excellence for Malaria Research (ICEMR) network in a variety of malaria-endemic settings. First, we discuss various novel approaches to understand malaria incidence and gametocytemia, focusing on Plasmodium falciparum and Plasmodium vivax. Second, we describe and compare different parasite genotyping methods commonly used in malaria epidemiology and population genetics. Finally, we discuss potential applications of molecular epidemiological tools and methods toward malaria control and elimination efforts. © The American Society of Tropical Medicine and Hygiene.

One hundred fold increase in current carrying capacity in a carbon nanotube–copper composite

PubMed Central

Subramaniam, Chandramouli; Yamada, Takeo; Kobashi, Kazufumi; Sekiguchi, Atsuko; Futaba, Don N.; Yumura, Motoo; Hata, Kenji

2013-01-01

Increased portability, versatility and ubiquity of electronics devices are a result of their progressive miniaturization, requiring current flow through narrow channels. Present-day devices operate close to the maximum current-carrying-capacity (that is, ampacity) of conductors (such as copper and gold), leading to decreased lifetime and performance, creating demand for new conductors with higher ampacity. Ampacity represents the maximum current-carrying capacity of the object that depends both on the structure and material. Here we report a carbon nanotube–copper composite exhibiting similar conductivity (2.3–4.7 × 105 S cm−1) as copper (5.8 × 105 S cm−1), but with a 100-times higher ampacity (6 × 108 A cm−2). Vacuum experiments demonstrate that carbon nanotubes suppress the primary failure pathways in copper as observed by the increased copper diffusion activation energy (∼2.0 eV) in carbon nanotube–copper composite, explaining its higher ampacity. This is the only material with both high conductivity and high ampacity, making it uniquely suited for applications in microscale electronics and inverters. PMID:23877359

One hundred fold increase in current carrying capacity in a carbon nanotube-copper composite

NASA Astrophysics Data System (ADS)

Subramaniam, Chandramouli; Yamada, Takeo; Kobashi, Kazufumi; Sekiguchi, Atsuko; Futaba, Don N.; Yumura, Motoo; Hata, Kenji

2013-07-01

Increased portability, versatility and ubiquity of electronics devices are a result of their progressive miniaturization, requiring current flow through narrow channels. Present-day devices operate close to the maximum current-carrying-capacity (that is, ampacity) of conductors (such as copper and gold), leading to decreased lifetime and performance, creating demand for new conductors with higher ampacity. Ampacity represents the maximum current-carrying capacity of the object that depends both on the structure and material. Here we report a carbon nanotube-copper composite exhibiting similar conductivity (2.3-4.7 × 105Scm-1) as copper (5.8 × 105Scm-1), but with a 100-times higher ampacity (6 × 108Acm-2). Vacuum experiments demonstrate that carbon nanotubes suppress the primary failure pathways in copper as observed by the increased copper diffusion activation energy (~2.0eV) in carbon nanotube-copper composite, explaining its higher ampacity. This is the only material with both high conductivity and high ampacity, making it uniquely suited for applications in microscale electronics and inverters.

Nonlinear calculation of the m=1 internal kink instability in current carrying stellarators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wakatani, M.

1978-02-01

Nonlinear properties of the m=1 internal kink mode are shown in a low beta current carrying stellarator. The effects of the external helical magnetic fields are considered through a rotational transform and the magnetic surface is assumed to be circular. Magnetic surfaces inside the iota sub eta + iota sub sigma = 1 surface shift and deform non-circularly, while magnetic surfaces outside the iota sub eta + iota sub sigma = 1 are not disturbed, where iota sub eta is a rotational transform due to helical magnetic fields and iota sub sigma is due to a plasma current. Many highermore » harmonics are excited after the fundamental mode saturates. When the external helical magnetic fields are lowered, the m=1 tearing mode similar to that in a low beta Tokamak grows and magnetic islands appear near the iota sub eta + iota sub sigma = 1 surface. For adequate helical magnetic fields, the current carrying stellarator becomes stable against both the m=1 internal kink mode and the m=1 internal kink mode and the m=1 tearing mode, without lowering the rotational transform.« less

Direct current power delivery system and method

DOEpatents

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.

Silent calcium channels in skeletal muscle fibers of the crustacean Atya lanipes.

PubMed

Monterrubio, J; Lizardi, L; Zuazaga, C

2000-01-01

The superficial (tonic) abdominal flexor muscles of Atya lanipes do not generate Ca(2+) action potentials when depolarized and have no detectable inward Ca(2+) current. These fibers, however, are strictly dependent on Ca(2+) influx for contraction, suggesting that they depend on Ca(2+)-induced Ca(2+) release for contractile activation. The nature of the communication between Ca(2+) channels in the sarcolemmal/tubular membrane and Ca(2+) release channels in the sarcoplasmic reticulum in this crustacean muscle was investigated. The effects of dihydropyridines on tension generation and the passive electrical response were examined in current-clamped fibers: Bay K 8644 enhanced tension about 100% but did not alter the passive electrical response; nifedipine inhibited tension by about 70%. Sr(2+) and Ba(2+) action potentials could be elicited in Ca(2+)-free solutions. The spikes generated by these divalent cations were abolished by nifedipine. As the Sr(2+) or Ba(2+) concentrations were increased, the amplitudes of the action potentials and their maximum rate of rise, V(max), increased and tended towards saturation. Three-microelectrode voltage-clamp experiments showed that even at high (138 mm) extracellular Ca(2+) concentration the channels were silent, i.e., no inward Ca(2+) current was detected. In Ca(2+)-free solutions, inward currents carried by 138 mm Sr(2+) or Ba(2+) were observed. The currents activated at voltages above -40 mV and peaked at about 0 mV. This voltage-activation profile and the sensitivity of the channels to dihydropyridines indicate that they resemble L-type Ca(2+) channels. Peak inward current density values were low, ca. -33 microA/cm(2) for Sr(2+) and -14 microA/cm(2) for Ba(2+), suggesting that Ca(2+) channels are present at a very low density. It is concluded that Ca(2+)-induced Ca(2+) release in this crustacean muscle operates with an unusually high gain: Ca(2+) influx through the silent Ca(2+) channels is too low to generate a macroscopic inward current, but increases sufficiently the local concentration of Ca(2+) in the immediate vicinity of the sarcoplasmic reticulum Ca(2+) release channels to trigger the highly amplified release of Ca(2+) required for tension generation.

Very low cost stand-off suicide bomber detection system using human gait analysis to screen potential bomb carrying individuals

NASA Astrophysics Data System (ADS)

Greneker, Gene, III

2005-05-01

Individuals who carry bombs on their bodies and detonate those bombs in public places are a security problem. There is belief that suicide bombings currently used in the mid-east may spread to the United States if the organized terrorist groups operating in the United States are not identified and the cell members arrested. While bombs in vehicles are the primary method currently used to spread terror in Iraq, U. S. warfighters are starting to face suicide bombers. This may become more of the situation if a stand-off detection capability is developed for the vehicle bomb case. This paper presents a concept, that if developed and commercialized, could provide an inexpensive suicide bomber screening system that could be used to screen individuals approaching a checkpoint while the individual is still 500 to 1,000 feet from the checkpoint. The proposed system measures both the radar cross-section of the individual and the radar derived gait characteristics that are associated with individuals carrying a bomb on their body. GTRI researchers propose to use human gait characteristics, as detected by radar, to determine if a human subject who is carrying no visible load on the body is actually carrying a concealed load under their clothes. The use of radar gait as a metric for the detection (as opposed to a video system) of a suicide bomber is being proposed because detection of gait characteristics are thought to be less sensitive to where the bomb is located on the body, lighting conditions, and the fact that the legs may be shrouded in a robe. The detection of a bomb using radar gait analysis may also prove to be less sensitive to changing tactics regarding where the bomb is placed on the body. An inert suicide bomb vest was constructed using water pipes to simulate the explosive devices. Wiring was added to simulated detonators. The vest weighs approximately 35 pounds. Radar data was taken on the volunteer subject wearing the vest that simulated the suicide bomb. This paper discusses the findings after the data was analyzed. A Provisional Patent has been filed by Georgia Tech Research Corporation on the subject matter that is discussed in this paper.

Mouths of the Amazon River, Brazil, South America

NASA Technical Reports Server (NTRS)

1991-01-01

Huge sediment loads from the interior of the country flow through the Mouths of the Amazon River, Brazil (0.5S, 50.0W). The river current carries hundreds of tons of sediment through the multiple outlets of the great river over 100 miles from shore before it is carried northward by oceanic currents. The characteristic 'fair weather cumulus' pattern of low clouds over the land but not over water may be observed in this scene.

Mouths of the Amazon River, Brazil, South America

NASA Image and Video Library

1991-08-11

Huge sediment loads from the interior of the country flow through the Mouths of the Amazon River, Brazil (0.5S, 50.0W). The river current carries hundreds of tons of sediment through the multiple outlets of the great river over 100 miles from shore before it is carried northward by oceanic currents. The characteristic "fair weather cumulus" pattern of low clouds over the land but not over water may be observed in this scene.

Health information technology adoption in New Zealand optometric practices.

PubMed

Heidarian, Ahmadali; Mason, David

2013-11-01

Health information technology (HIT) has the potential to fundamentally change the practice of optometry and the relationship between optometrists and patients and to improve clinical outcomes. This paper aims to provide data on how health information technology is currently being used in New Zealand optometric practices. Also this paper aims to explore the potential benefits and barriers to the future adoption of health information technology in New Zealand. One hundred and six New Zealand optometrists were surveyed about their current use of health information technology and about potential benefits and barriers. In addition, 12 semi-structured interviews were carried out with leaders of health information technology in New Zealand optometry. The areas of interest were the current and intended use of HIT, the potential benefits of and barriers to using HIT in optometric offices and the level of investment in health information technology. Nearly all optometrists (98.7 per cent) in New Zealand use computers in their practices and 93.4 per cent of them use a computer in their consulting room. The most commonly used clinical assessment technology in optometric practices in New Zealand was automated perimeter (97.1 per cent), followed by a digital fundus/retinal camera (82.6 per cent) and automated lensometer (62.9 per cent). The pachymeter is the technology that most respondents intended to purchase in the next one to five years (42.6 per cent), followed by a scanning laser ophthalmoscope (36.8 per cent) and corneal topographer (32.9 per cent). The main benefits of using health information technology in optometric practices were improving patient perceptions of ‘state of the art’ practice and providing patients with information and digital images to explain the results of assessment. Barriers to the adoption of HIT included the need for frequent technology upgrades, cost, lack of time for implementation, and training. New Zealand optometrists are using HIT broadly in their practices and expect HIT use to increase over time.

An optimized top contact design for solar cell concentrators

NASA Technical Reports Server (NTRS)

Desalvo, Gregory C.; Barnett, Allen M.

1985-01-01

A new grid optimization scheme is developed for point focus solar cell concentrators which employs a separated grid and busbar concept. Ideally, grid lines act as the primary current collectors and receive all of the current from the semiconductor region. Busbars are the secondary collectors which pick up current from the grids and carry it out of the active region of the solar cell. This separation of functions leads to a multithickness metallization design, where the busbars are made larger in cross section than the grids. This enables the busbars to carry more current per unit area of shading, which is advantageous under high solar concentration where large current densities are generated. Optimized grid patterns using this multilayer concept can provide a 1.6 to 20 percent increase in output power efficiency over optimized single thickness grids.

Multibias and thermal behavior of microwave GaN and GaAs based HEMTs

NASA Astrophysics Data System (ADS)

Alim, Mohammad A.; Rezazadeh, Ali A.; Gaquiere, Christophe

2016-12-01

Multibias and thermal characterizations on 0.25 μm × (2 × 100) μm AlGaN/GaN/SiC HEMT and 0.5 μm × (2 × 100) μm AlGaAs/InGaAs pseudomorphic HEMT have carried out for the first time. Two competitive device technologies are investigated with the variations of bias and temperature in order to afford a detailed realization of their potentialities. The main finding includes the self heating effect in the GaN device, zero temperature coefficient points at the drain current and transconductance in the GaAs device. The thermal resistance RTH of 7.1, 8.2 and 9.4 °C mm/W for the GaN device was estimated at 25, 75 and 150 °C respectively which are consistent with those found in the open literature. The temperature trend of the threshold voltage VT, Schottky barrier height ϕb, sheet charge densities of two dimensional electron gas ns, and capacitance under the gate Cg are exactly opposite in the two devices; whereas the knee voltage Vk, on resistance Ron, and series resistance Rseries are shows similar trend. The multi-bias and thermal behavior of the output current Ids, output conductance gds, transconductance gm, cut-off frequency ft, maximum frequency fmax, effective velocity of electron, veff and field dependent mobility, μ demonstrates a great potential of GaN device. These results provide some valuable insights for technology of preference for future and current applications.

High-Energy Electron Shell in ECR Ion Source:

NASA Astrophysics Data System (ADS)

Niimura, M. G.; Goto, A.; Yano, Y.

1997-05-01

As an injector of cyclotrons and RFQ linacs, ECR ion source (ECRIS) is expected to deliver highly charged ions (HCI) at high beam-current (HBC). Injections of light gases and supplementary electrons have been employed for enhancement of HCI and HBC, respectively. Further amelioration of the performance may be feasible by investigating the hot-electron ring inside an ECRIS. Its existence has been granted because of the MeV of Te observable via X-ray diagnostics. However, its location, acceleration mechanism, and effects on the performance are not well known.We found them by deriving the radially negative potential distribution for an ECRIS from measured endloss-current data. It was evidenced from a hole-burning on the parabolic potential profile (by uniformly distributed warm-electron space charges of 9.5x10^5cm-3) and from a local minimum of the electrostatically-trapped ion distribution. A high-energy electron shell (HEES) was located right on the ECR-radius of 6 cm with shell-halfwidth of 1 cm. Such a thin shell around core plasma can only be generated by the Sadeev-Shapiro or v_phxBz acceleration mechanism that can raise Te up to a relativistic value. Here, v_ph is the phase velocity of ES Bernstein waves propagating backwards against incident microwave and Bz the axial mirror magnetic field. The HEES carries diamagnetic current which reduces the core magnetic pressure, thereby stabilizing the ECR surface against driftwave instabilities similarly to gas-mixing.

The role of central venous oxygen saturation, blood lactate, and central venous-to-arterial carbon dioxide partial pressure difference as a goal and prognosis of sepsis treatment.

PubMed

Wittayachamnankul, Borwon; Chentanakij, Boriboon; Sruamsiri, Kamphee; Chattipakorn, Nipon

2016-12-01

The current practice in treatment of severe sepsis and septic shock is to ensure adequate oxygenation and perfusion in patients, along with prompt administration of antibiotics, within 6 hours from diagnosis, which is considered the "golden hour" for the patients. One of the goals of treatment is to restore normal tissue perfusion. With this goal in mind, some parameters have been used to determine the success of treatment and mortality rate; however, none has been proven to be the best predictor of mortality rate in sepsis patients. Despite growing evidence regarding the prognostic indicators for mortality in sepsis patients, inconsistent reports exist. This review comprehensively summarizes the reports regarding the frequently used parameters in sepsis including central venous oxygen saturation, blood lactate, and central venous-to-arterial carbon dioxide partial pressure difference, as prognostic indicators for clinical outcomes in sepsis patients. Moreover, consistent findings and inconsistent reports for their pathophysiology and the potential mechanisms for their use as well as their limitations in sepsis patients are presented and discussed. Finally, a schematic strategy for potential management and benefits in sepsis patients is proposed based upon these current available data. There is currently no ideal biomarker that can indicate prognosis, predict progression of the disease, and guide treatment in sepsis. Further studies are needed to be carried out to identify the ideal biomarker that has all the desired properties. Copyright © 2016 Elsevier Inc. All rights reserved.

Exact analytical solution of a classical Josephson tunnel junction problem

NASA Astrophysics Data System (ADS)

Kuplevakhsky, S. V.; Glukhov, A. M.

2010-10-01

We give an exact and complete analytical solution of the classical problem of a Josephson tunnel junction of arbitrary length W ɛ(0,∞) in the presence of external magnetic fields and transport currents. Contrary to a wide-spread belief, the exact analytical solution unambiguously proves that there is no qualitative difference between so-called "small" (W≪1) and "large" junctions (W≫1). Another unexpected physical implication of the exact analytical solution is the existence (in the current-carrying state) of unquantized Josephson vortices carrying fractional flux and located near one of the edges of the junction. We also refine the mathematical definition of critical transport current.

Potential criminal adversaries of nuclear programs: a portrait

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jenkins, B.M.

1980-07-01

This paper examines the possibility that terrorists or other kinds of criminals might attempt to seize or sabotage a nuclear facility, steal nuclear material, or carry out other criminal activities in the nuclear domain which has created special problems for the security of nuclear programs. This paper analyzes the potential threat. Our tasks was to describe the potential criminal adversary, or rather the spectrum of potential adversaries who conceivably might carry out malevolent criminal actions against nuclear programs and facilities. We were concerned with both the motivations as well as the material and operational capabilities likely to be displayed bymore » various categories of potential nuclear adversaries.« less

Flexible Feature-Based Inhibition in Visual Search Mediates Magnified Impairments of Selection: Evidence from Carry-Over Effects under Dynamic Preview-Search Conditions

ERIC Educational Resources Information Center

Andrews, Lucy S.; Watson, Derrick G.; Humphreys, Glyn W.; Braithwaite, Jason J.

2011-01-01

Evidence for inhibitory processes in visual search comes from studies using preview conditions, where responses to new targets are delayed if they carry a featural attribute belonging to the old distractor items that are currently being ignored--the negative carry-over effect (Braithwaite, Humphreys, & Hodsoll, 2003). We examined whether…

Coupling time constants of striated and copper-plated coated conductors and the potential of striation to reduce shielding-current-induced fields in pancake coils

NASA Astrophysics Data System (ADS)

Amemiya, Naoyuki; Tominaga, Naoki; Toyomoto, Ryuki; Nishimoto, Takuma; Sogabe, Yusuke; Yamano, Satoshi; Sakamoto, Hisaki

2018-07-01

The shielding-current-induced field is a serious concern for the applications of coated conductors to magnets. The striation of the coated conductor is one of the countermeasures, but it is effective only after the decay of the coupling current, which is characterised with the coupling time constant. In a non-twisted striated coated conductor, the coupling time constant is determined primarily by its length and the transverse resistance between superconductor filaments, because the coupling current could flow along its entire length. We measured and numerically calculated the frequency dependences of magnetisation losses in striated and copper-plated coated conductors with various lengths and their stacks at 77 K and determined their coupling time constants. Stacked conductors simulate the turns of a conductor wound into a pancake coil. Coupling time constants are proportional to the square of the conductor length. Stacking striated coated conductors increases the coupling time constants because the coupling currents in stacked conductors are coupled to one another magnetically to increase the mutual inductances for the coupling current paths. We carried out the numerical electromagnetic field analysis of conductors wound into pancake coils and determined their coupling time constants. They can be explained by the length dependence and mutual coupling effect observed in stacked straight conductors. Even in pancake coils with practical numbers of turns, i.e. conductor lengths, the striation is effective to reduce the shielding-current-induced fields for some dc applications.

Renewable energy and power cooperation between China and six Latin American nations

NASA Astrophysics Data System (ADS)

Xie, Yuetao; Yan, Bingzhong; Zhou, Shichun

2018-02-01

China has been entitled the biggest supplier and largest market of renewable energy for the past few years. With One Belt and One Road initiative carrying on, the China’s renewable energy industry is looking for opportunities across the world. Latin America, which has rich renewable energy resources and urge demand for a cleaner and more sustainable energy system, may become an important target market for China. The prospect and potential of renewable energy cooperation between China and Latin America are promising. In this paper, six Latin American nations of varied background were selected as study cases. Their nation profile, energy resources, power market, and energy development trends were analysed, and the cooperation prospect and potential between these nations and China in renewable energy sector were discussed. The results indicate that Argentina and Bolivia are most potential cooperation partners, and project development and equipment manufacturing of non-hydro renewable energy, along with power grid upgrading are the prioritized areas. In addition, recommendations and solutions addressing the issues and challenges incurred in the current bilateral energy cooperation between China and Latin American nations were proposed.

Molecular Modeling and Evaluation of Novel Dibenzopyrrole Derivatives as Telomerase Inhibitors and Potential Drug for Cancer Therapy.

PubMed

Kalathiya, Umesh; Padariya, Monikaben; Baginski, Maciej

2014-01-01

During previous years, many studies on synthesis, as well as on anti-tumor, anti-inflammatory and anti-bacterial activities of the pyrazole derivatives have been described. Certain pyrazole derivatives exhibit important pharmacological activities and have proved to be useful template in drug research. Considering importance of pyrazole template, in current work the series of novel inhibitors were designed by replacing central ring of acridine with pyrazole ring. These heterocyclic compounds were proposed as a new potential base for telomerase inhibitors. Obtained dibenzopyrrole structure was used as a novel scaffold structure and extension of inhibitors was done by different functional groups. Docking of newly designed compounds in the telomerase active site (telomerase catalytic subunit TERT) was carried out. All dibenzopyrrole derivatives were evaluated by three docking programs: CDOCKER, Ligandfit docking (Scoring Functions) and AutoDock. Compound C_9g, C_9k and C_9l performed best in comparison to all designed inhibitors during the docking in all methods and in interaction analysis. Introduction of pyrazole and extension of dibenzopyrrole in compounds confirm that such compound may act as potential telomerase inhibitors.

Surface enhanced Raman spectroscopy of the silver/KCl, triethylenediamine (DABCO), water system

NASA Astrophysics Data System (ADS)

Irish, D. E.; Guzonas, D.; Atkinson, G. F.

1985-07-01

1,4-Diazabicyclo[2.2.2]octane, (N(CH 2CH 2) 3N), usually abbreviated DABCO or DBO, is a symmetric top molecule of point group D 3h. SERS experiments have been carried out in an optical electrochemical cell using a silver electrode roughened by a single oxidation-reduction cycle (ORC). The observed SERS spectra contained four strong bands at 624, 798, 990 and 1351 cm -1, all A' 1 totally symmetric modes. The same bands were also observed in SERS spectra of DABCO adsorbed on colloidal gold. In the electrochemical experiments, the maximum of SERS-intensity versus electrode potential plots was observed to shift to less negative potentials as the wavelength of the exciting line was shifted to the red. The radically-altered, relative intensities of the observed bands, as well as observed changes in relative intensity as a function of electrode potential, have been interpreted as a selective enhancement of those normal modes which have as a major component of vibrational motion the C-C stretch. These observations are correlated with current theories concerning the SERS mechanism, especially those involving charge transfer (CT).

Life cycles of transient planetary waves

NASA Technical Reports Server (NTRS)

Nathan, Terrence

1993-01-01

In recent years there has been an increasing effort devoted to understanding the physical and dynamical processes that govern the global-scale circulation of the atmosphere. This effort has been motivated, in part, from: (1) a wealth of new satellite data; (2) an urgent need to assess the potential impact of chlorofluorocarbons on our climate; (3) an inadequate understanding of the interactions between the troposphere and stratosphere and the role that such interactions play in short and long-term climate variability; and (4) the realization that addressing changes in our global climate requires understanding the interactions among various components of the earth system. The research currently being carried out represents an effort to address some of these issues by carrying out studies that combine radiation, ozone, seasonal thermal forcing and dynamics. Satellite and ground-based data that is already available is being used to construct basic states for our analytical and numerical models. Significant accomplishments from 1991-1992 are presented and include the following: ozone-dynamics interaction; (2) periodic local forcing and low frequency variability; and (3) steady forcing and low frequency variability.

Specialized science.

PubMed

Casadevall, Arturo; Fang, Ferric C

2014-04-01

As the body of scientific knowledge in a discipline increases, there is pressure for specialization. Fields spawn subfields that then become entities in themselves that promote further specialization. The process by which scientists join specialized groups has remarkable similarities to the guild system of the middle ages. The advantages of specialization of science include efficiency, the establishment of normative standards, and the potential for greater rigor in experimental research. However, specialization also carries risks of monopoly, monotony, and isolation. The current tendency to judge scientific work by the impact factor of the journal in which it is published may have roots in overspecialization, as scientists are less able to critically evaluate work outside their field than before. Scientists in particular define themselves through group identity and adopt practices that conform to the expectations and dynamics of such groups. As part of our continuing analysis of issues confronting contemporary science, we analyze the emergence and consequences of specialization in science, with a particular emphasis on microbiology, a field highly vulnerable to balkanization along microbial phylogenetic boundaries, and suggest that specialization carries significant costs. We propose measures to mitigate the detrimental effects of scientific specialism.

Functional neuronal processing of human body odors.

PubMed

Lundström, Johan N; Olsson, Mats J

2010-01-01

Body odors carry informational cues of great importance for individuals across a wide range of species, and signals hidden within the body odor cocktail are known to regulate several key behaviors in animals. For a long time, the notion that humans may be among these species has been dismissed. We now know, however, that each human has a unique odor signature that carries information related to his or her genetic makeup, as well as information about personal environmental variables, such as diet and hygiene. Although a substantial number of studies have investigated the behavioral effects of body odors, only a handful have studied central processing. Recent studies have, however, demonstrated that the human brain responds to fear signals hidden within the body odor cocktail, is able to extract kin specific signals, and processes body odors differently than other perceptually similar odors. In this chapter, we provide an overview of the current knowledge of how the human brain processes body odors and the potential importance these signals have for us in everyday life. Copyright © 2010 Elsevier Inc. All rights reserved.

Effects of hydrogen-charging on the properties of S235JR steel

NASA Astrophysics Data System (ADS)

Pietkun-Greber, Izabela

2017-10-01

The paper presents the test results of the S235JR steel susceptibility to damage under the influence of hydrogen. The test of mechanical properties was performed on the basis of a static stretch test of non-hydrogenated samples and after cathodic polarization. Electrochemical measurements for the assessment of corrosion resistance of non-hydrogenated and hydrogenated steels were carried out using open circuit potential measurement and registering of potentiodynamic polarization curves in a three-electrode measuring system. Hydrogenation was carried out for between 3 and 24 hours in a solution of 0.1 N sulfuric acid (VI) with the addition of 2 mg/dm 3 of arsenic oxide (III) at an electric current density of 10 mA/cm2. The hydrogen content in the steel before and after saturation with hydrogen was determined using the analyzer. Fracture samples after tensile test were observed using scanning electron microscope. The results of the research showed that as the hydrogen concentration in the examined steel increased (the lengthening of the saturation time), the deterioration of its mechanical and electrochemical properties occurred.

Accelerative Forces Associated with Routine Inhouse Transportation of Rodent Cages

PubMed Central

Hurst, Keriann; Litwak, Kenneth N

2012-01-01

Transportation of rodents has repeatedly been demonstrated to potentially affect research outcomes. In addition, rapid acceleration and deceleration have marked physiologic effects. The current study determined the accelerative forces associated with common types of animal transportation within the institution and means of reducing these effects. A rodent-sized (24 g) accelerometer was placed in a standard polycarbonate mouse cage, which then was hand-carried or loaded onto a plastic, small metal, or large metal cart. The cage then moved along a set path that included several flooring types and obstacles. Accelerative forces within the mouse cage varied by as much as 35 m/s2 in as little as 1 s, primarily along the vertical axis (Z-axis). Measured acceleration was greatest with the plastic cart and lowest during hand-carrying. The placement of a towel under the cage dampened in-cage acceleration due to cart use by more than 50%, whereas a similarly located underpad had no significant effect. These data document that small rodents typically are exposed to considerable motion during transportation. The resulting physical and physiologic effects could affect study outcomes. PMID:23312081

Specialized Science

PubMed Central

Fang, Ferric C.

2014-01-01

As the body of scientific knowledge in a discipline increases, there is pressure for specialization. Fields spawn subfields that then become entities in themselves that promote further specialization. The process by which scientists join specialized groups has remarkable similarities to the guild system of the middle ages. The advantages of specialization of science include efficiency, the establishment of normative standards, and the potential for greater rigor in experimental research. However, specialization also carries risks of monopoly, monotony, and isolation. The current tendency to judge scientific work by the impact factor of the journal in which it is published may have roots in overspecialization, as scientists are less able to critically evaluate work outside their field than before. Scientists in particular define themselves through group identity and adopt practices that conform to the expectations and dynamics of such groups. As part of our continuing analysis of issues confronting contemporary science, we analyze the emergence and consequences of specialization in science, with a particular emphasis on microbiology, a field highly vulnerable to balkanization along microbial phylogenetic boundaries, and suggest that specialization carries significant costs. We propose measures to mitigate the detrimental effects of scientific specialism. PMID:24421049

Electronic and Interfacial Properties of PD/6H-SiC Schottky Diode Gas Sensors

NASA Technical Reports Server (NTRS)

Chen, Liang-Yu; Hunter, Gary W.; Neudeck, Philip G.; Bansal, Gaurav; Petit, Jeremy B.; Knight, Dak; Liu, Chung-Chiun; Wu, Qinghai

1996-01-01

Pd/SiC Schottky diodes detect hydrogen and hydrocarbons with high sensitivity. Variation of the diode temperature from 100 C to 200 C shows that the diode sensitivity to propylene is temperature dependent. Long-term heat treating at 425 C up to 140 hours is carried out to determine the effect of extended heat treating on the diode properties and gas sensitivity. The heat treating significantly affects the diode's capacitive characteristics, but the diode's current carrying characteristics are much more stable with a large response to hydrogen. Scanning Electron Microscopy and X-ray Spectrometry studies of the Pd surface after the heating show cluster formation and background regions with grain structure observed in both regions. The Pd and Si concentrations vary between grains. Auger Electron Spectroscopy depth profiles revealed that the heat treating promoted interdiffusion and reaction between the Pd and SiC dw broadened the interface region. This work shows that Pd/SiC Schottky diodes have significant potential as high temperature gas sensors, but stabilization of the structure is necessary to insure their repeatability in long-term, high temperature applications.

Factor V Leiden as a common genetic risk factor for venous thromboembolism.

PubMed

Horne, McDonald K; McCloskey, Donna Jo

2006-01-01

To increase nurses' knowledge of the Factor V Leiden (FVL) genetic trait for venous thromboembolism. An overview of the history, prevalence, and predisposition of the FVL genetic mutation, including who should be tested and how and in what circumstances people with FVL should be treated. FVL is the most commonly recognized genetic trait associated with venous thrombosis. It is found predominantly in Caucasian populations. Biochemically it causes "activated protein C resistance (APCR)." The decision to test for FVL depends on whether the information gained will potentially improve the health care of the person or family. For people who have had deep venous thrombosis, testing for FVL will likely not alter treatment approaches. Currently the advantage for testing is primarily limited to asymptomatic family members who carry FVL and who have had deep vein thrombosis. Close relatives who also carry the mutated gene might benefit from prophylactic anticoagulation when their risk of thrombosis is increased by temporary factors such as surgery. Nurses are in a unique position to provide accurate information and counseling when patients and their family members are presented with the results of thrombophilia testing.

Quantum storage of orbital angular momentum entanglement in cold atomic ensembles

NASA Astrophysics Data System (ADS)

Shi, Bao-Sen; Ding, Dong-Sheng; Zhang, Wei

2018-02-01

Electromagnetic waves have both spin momentum and orbital angular momentum (OAM). Light carrying OAM has broad applications in micro-particle manipulation, high-precision optical metrology, and potential high-capacity optical communications. In the concept of quantum information, a photon encoded with information in its OAM degree of freedom enables quantum networks to carry much more information and increase their channel capacity greatly compared with those of current technology because of the inherent infinite dimensions for OAM. Quantum memories are indispensable to construct quantum networks. Storing OAM states has attracted considerable attention recently, and many important advances in this direction have been achieved during the past few years. Here we review recent experimental realizations of quantum memories using OAM states, including OAM qubits and qutrits at true single photon level, OAM states entangled in a two-dimensional or a high-dimensional space, hyperentanglement and hybrid entanglement consisting of OAM and other degree of freedom in a physical system. We believe that all achievements described here are very helpful to study quantum information encoded in a high-dimensional space.

High altitude observations of Birkeland currents

NASA Technical Reports Server (NTRS)

Russell, C. T.

1977-01-01

Several models of field-aligned currents (Birkeland currents) in the magnetosphere are discussed, and high altitude observations of these currents, carried out with the aid of highly eccentric earth-orbiting spacecraft of the OGO and IMP series, are reviewed. The essential roles of Birkeland currents are identified: they relieve charge imbalances, transmit stresses, and lead to particle acceleration anomalous resistivity.

Electrical stator

DOEpatents

Fanning, Alan W.; Olich, Eugene E.

1994-01-01

An electrical stator of an electromagnetic pump includes first and second spaced apart coils each having input and output terminals for carrying electrical current. An elongate electrical connector extends between the first and second coils and has first and second opposite ends. The connector ends include respective slots receiving therein respective ones of the coil terminals to define respective first and second joints. Each of the joints includes a braze filler fixedly joining the connector ends to the respective coil terminals for carrying electrical current therethrough.

Study of Current Practice and Future Advancements in Blood Management and Effectiveness of a Multimodality Training Program on Improving Transfusion Knowledge, Practice and Outcomes

DTIC Science & Technology

2012-08-01

to trauma, surgery or blood diseases such as anemia, hemophilia or sickle- cell disease. But transfusions carry risks. Current practices are often...Blood Management Topic 4: Diagnosis of Red cell disorders and oxygen carrying capacity Topic 5: Diagnosis of Disorders in homeostasis Topic 6...the Clinical Transfusion Medicine Committee of the AABB. Red Blood Cell Transfusion: A Clinical Practice Guideline From the AABB. Ann Intern Med

Identifying and Classifying Pollution Hotspots to Guide Watershed Management in a Large Multiuse Watershed.

PubMed

Su, Fangli; Kaplan, David; Li, Lifeng; Li, Haifu; Song, Fei; Liu, Haisheng

2017-03-03

In many locations around the globe, large reservoir sustainability is threatened by land use change and direct pollution loading from the upstream watershed. However, the size and complexity of upstream basins makes the planning and implementation of watershed-scale pollution management a challenge. In this study, we established an evaluation system based on 17 factors, representing the potential point and non-point source pollutants and the environmental carrying capacity which are likely to affect the water quality in the Dahuofang Reservoir and watershed in northeastern China. We used entropy methods to rank 118 subwatersheds by their potential pollution threat and clustered subwatersheds according to the potential pollution type. Combining ranking and clustering analyses allowed us to suggest specific areas for prioritized watershed management (in particular, two subwatersheds with the greatest pollution potential) and to recommend the conservation of current practices in other less vulnerable locations (91 small watersheds with low pollution potential). Finally, we identified the factors most likely to influence the water quality of each of the 118 subwatersheds and suggested adaptive control measures for each location. These results provide a scientific basis for improving the watershed management and sustainability of the Dahuofang reservoir and a framework for identifying threats and prioritizing the management of watersheds of large reservoirs around the world.

Identifying and Classifying Pollution Hotspots to Guide Watershed Management in a Large Multiuse Watershed

PubMed Central

Su, Fangli; Kaplan, David; Li, Lifeng; Li, Haifu; Song, Fei; Liu, Haisheng

2017-01-01

In many locations around the globe, large reservoir sustainability is threatened by land use change and direct pollution loading from the upstream watershed. However, the size and complexity of upstream basins makes the planning and implementation of watershed-scale pollution management a challenge. In this study, we established an evaluation system based on 17 factors, representing the potential point and non-point source pollutants and the environmental carrying capacity which are likely to affect the water quality in the Dahuofang Reservoir and watershed in northeastern China. We used entropy methods to rank 118 subwatersheds by their potential pollution threat and clustered subwatersheds according to the potential pollution type. Combining ranking and clustering analyses allowed us to suggest specific areas for prioritized watershed management (in particular, two subwatersheds with the greatest pollution potential) and to recommend the conservation of current practices in other less vulnerable locations (91 small watersheds with low pollution potential). Finally, we identified the factors most likely to influence the water quality of each of the 118 subwatersheds and suggested adaptive control measures for each location. These results provide a scientific basis for improving the watershed management and sustainability of the Dahuofang reservoir and a framework for identifying threats and prioritizing the management of watersheds of large reservoirs around the world. PMID:28273834

A Study on the Performance and Electrochemistry of Bryophyllum pinnatum Leaf (BPL) Electrochemical Cell

NASA Astrophysics Data System (ADS)

Al Mamun, Mohammad; Khan, M. I.; Sarker, M. H.; Khan, K. A.

The study was carried out to investigate on an innovative invention, Pathor Kuchi Leaf (PKL) electrochemical cell, which is fueled with PKL sap of widely available plant called Bryophyllum pinnatum as an energy source for use in PKL battery to generate electricity. This battery, a primary source of electricity, has several order of magnitude longer shelf-lives than the traditional Galvanic cell battery, is still under investigation. In this regard, we have conducted some experiments using various instruments including Atomic Absorption Spectrophotometer (AAS), Ultra-Violet Visible spectrophotometer (UV-Vis), pH meter, Ampere-Volt-Ohm Meter etc. The AAS, UV-Vis and pH metric analysis data provided that the potential and current were produced as the Zn electrode itself acts as reductant while Cu2+and H+ ions are behaving as oxidant. The significant influence of secondary salt on current and potential leads to the dissociation of weak organic acids in PKL juice, and subsequent enrichment to the reactant ions by the secondary salt effects. However, the liquid junction potential was not as great as minimized with the opposite transference of organic acid anions and H + ions as their dissimilar ionic mobilities. Moreover, the large value of equilibrium constant (K) implies the big change in Gibbs free energy (ΔG), revealed the additional electrical work in presence of PKL sap. This easily fabricated high performance PKL battery can demonstrate an excellent promise during the off-peak across the country-side.

Spatial distribution of potentially bioavailable metals in surface soils of a contaminated sports ground in Galway, Ireland.

PubMed

Dao, Ligang; Morrison, Liam; Kiely, Ger; Zhang, Chaosheng

2013-04-01

Assessing the environmental risk of metal contamination in soils requires the determination of both total (TCs) and bioavailable (BCs) element concentrations. A total of 200 surface (0-10 cm) soil samples were collected from an urban sports ground (South Park) in Galway, Ireland, a former landfill and dumping site, which is currently under remediation. The potential BCs of metals were measured using ethylene-diamine-tetra-acetic acid (EDTA) extraction followed by inductively coupled plasma-optical emission spectrometry analysis, while the TCs were determined using portable X-ray fluorescence spectrometry. It was found that Zn was primarily present in the insoluble residue (EDTA un-extractable) fraction in soils, with the median ratio of BCs/TCs 0.27. However, Pb and Cu had higher ratios of BCs/TCs (median values of 0.60 and 0.39, respectively) suggesting that they are potentially more bioavailable in the soils. The spatial distribution maps showed that both TCs and BCs for Cu, Pb and Zn in the study area were spatially heterogeneous. It was found that the BCs exhibited generally similar spatial patterns as their TCs of Cu, Pb and Zn: high values were mainly located in the west, north-east and south-east portions of the study area, where only a thin layer of topsoil existed. It was recommended that the current remediation action for this site needs to be carried out on an urgent basis.

Extending to seasonal scales the current usage of short range weather forecasts and climate projections for water management in Spain

NASA Astrophysics Data System (ADS)

Rodriguez-Camino, Ernesto; Voces, José; Sánchez, Eroteida; Navascues, Beatriz; Pouget, Laurent; Roldan, Tamara; Gómez, Manuel; Cabello, Angels; Comas, Pau; Pastor, Fernando; Concepción García-Gómez, M.°; José Gil, Juan; Gil, Delfina; Galván, Rogelio; Solera, Abel

2016-04-01

This presentation, first, briefly describes the current use of weather forecasts and climate projections delivered by AEMET for water management in Spain. The potential use of seasonal climate predictions for water -in particular dams- management is then discussed more in-depth, using a pilot experience carried out by a multidisciplinary group coordinated by AEMET and DG for Water of Spain. This initiative is being developed in the framework of the national implementation of the GFCS and the European project, EUPORIAS. Among the main components of this experience there are meteorological and hydrological observations, and an empirical seasonal forecasting technique that provides an ensemble of water reservoir inflows. These forecasted inflows feed a prediction model for the dam state that has been adapted for this purpose. The full system is being tested retrospectively, over several decades, for selected water reservoirs located in different Spanish river basins. The assessment includes an objective verification of the probabilistic seasonal forecasts using standard metrics, and the evaluation of the potential social and economic benefits, with special attention to drought and flooding conditions. The methodology of implementation of these seasonal predictions in the decision making process is being developed in close collaboration with final users participating in this pilot experience.

Energetic Combustion Devices for Aerospace Propulsion and Power

NASA Technical Reports Server (NTRS)

Litchford, Ron J.

2000-01-01

Chemical reactions have long been the mainstay thermal energy source for aerospace propulsion and power. Although it is widely recognized that the intrinsic energy density limitations of chemical bonds place severe constraints on maximum realizable performance, it will likely be several years before systems based on high energy density nuclear fuels can be placed into routine service. In the mean time, efforts to develop high energy density chemicals and advanced combustion devices which can utilize such energetic fuels may yield worthwhile returns in overall system performance and cost. Current efforts in this vein are being carried out at NASA MSFC under the direction of the author in the areas of pulse detonation engine technology development and light metals combustion devices. Pulse detonation engines are touted as a low cost alternative to gas turbine engines and to conventional rocket engines, but actual performance and cost benefits have yet to be convincingly demonstrated. Light metal fueled engines also offer potential benefits in certain niche applications such as aluminum/CO2 fueled engines for endo-atmospheric Martian propulsion. Light metal fueled MHD generators also present promising opportunities with respect to electric power generation for electromagnetic launch assist. This presentation will discuss the applications potential of these concepts with respect to aero ace propulsion and power and will review the current status of the development efforts.

Southern limit of the Western South Atlantic mangroves: Assessment of the potential effects of global warming from a biogeographical perspective

NASA Astrophysics Data System (ADS)

Soares, Mário Luiz Gomes; Estrada, Gustavo Calderucio Duque; Fernandez, Viviane; Tognella, Mônica Maria Pereira

2012-04-01

The objective of the present study was to determine the exact location of the latitudinal limit of western South Atlantic mangroves, and to describe how these forests develop at this limit; as well as to analyze the potential responses of these communities to global warming. The study was carried out along the coast of Santa Catarina, Brazil. Specific studies on mangrove structure were carried out in the Santo Antônio Lagoon (28°28'34″S; 48°51'40″W). The coastline of Santa Catarina was surveyed for the occurrence of mangrove species. In the mangrove located at the southernmost distributional limit, the forest structure was characterized. Mean height and diameter, trunks density and basal area were calculated. Climatic and oceanographic factors controlling the occurrence and development of the mangrove forests at their latitudinal limit were analyzed, as well as the possible changes of this limit based on global warming scenarios. The results confirmed that the Santo Antônio Lagoon is the southern limit of the western South Atlantic mangroves. At this limit, the mangrove forests show a low degree of development, defined by low mean diameter and height, and high trunks density and trunks/tree ratio. The observed structural pattern and the local alternation of these forests with salt marsh species are typical of mangrove forests at their latitudinal limits. The absence of mangroves south of Laguna and forest structure at the latitudinal limit are controlled by rigorous climate and oceanographic characteristics. In response to the planetary warming process, we expect that mangroves will expand southward, as a consequence of an increase in air and ocean surface temperatures, a reduction in the incidence of frosts, an increased influence of the Brazil Current and a decreased influence of the Falkland Current, and the availability of sheltered estuarine systems for the establishment of new mangroves.

Potential carry-over of seeds from 11 common shrub and vine competitors of loblolly and shortleaf pines

Treesearch

Michael G. Shelton; Michael D. Cain

2002-01-01

Many of the competitors of the regeneration of loblolly and shortleaf pines (Pinus taeda, L. and Pinus echinata Mill., respectively) develop from seed disseminated on the site after reproduction cutting or from the seed bank. To evaluate the potential carry-over of the seeds from 11 shrub and vine competitors of these two...

Reciprocal Modulation of IK1–INa Extends Excitability in Cardiac Ventricular Cells

PubMed Central

Varghese, Anthony

2016-01-01

The inwardly rectifying potassium current (IK1) and the fast inward sodium current (INa) are reciprocally modulated in mammalian ventricular myocytes. An increase in the expression of channels responsible for one of these two currents results in a corresponding increase in expression of the other. These currents are critical in the propagation of action potentials (AP) during the normal functioning of the heart. This study identifies a physiological role for IK1–INa reciprocal modulation in ventricular fiber activation thresholds and conduction. Simulations of action potentials in single cells and propagating APs in cardiac fibers were carried out using an existing model of electrical activity in cardiac ventricular myocytes. The conductances, GK1, of the inwardly rectifying potassium current, and GNa, of the fast inward sodium current were modified independently and in tandem to simulate reciprocal modulation. In single cells, independent modulation of GK1 alone resulted in changes in activation thresholds that were qualitatively similar to those for reciprocal GK1–GNa modulation and unlike those due to independent modulation of GNa alone, indicating that GK1 determines the cellular activation threshold. On the other hand, the variations in conduction velocity in cardiac cell fibers were similar for independent GNa modulation and for tandem changes in GK1–GNa, suggesting that GNa is primarily responsible for setting tissue AP conduction velocity. Conduction velocity dependence on GK1–GNa is significantly affected by the intercellular gap junction conductance. While the effects on the passive fiber space constant due to changes in both GK1 and the intercellular gap junction conductance, Ggj, were in line with linear cable theory predictions, both conductances had surprisingly large effects on fiber activation thresholds. Independent modulation of GK1 rendered cardiac fibers inexcitable at higher levels of GK1 whereas tandem GK1–GNa changes allowed fibers to remain excitable at high GK1 values. Reciprocal modulation of the inwardly rectifying potassium current and the fast inward sodium current may have a functional role in allowing cardiac tissue to remain excitable when IK1 is upregulated. PMID:27895596

Symbiont interactions with non-native hosts limit the formation of new symbioses.

PubMed

Niepoth, Natalie; Ellers, Jacintha; Henry, Lee M

2018-03-12

Facultative symbionts are common in eukaryotes and can provide their hosts with significant fitness benefits. Despite the advantage of carrying these microbes, they are typically only found in a fraction of the individuals within a population and are often non-randomly distributed among host populations. It is currently unclear why facultative symbionts are only found in certain host individuals and populations. Here we provide evidence for a mechanism to help explain this phenomenon: that when symbionts interact with non-native host genotypes it can limit the horizontal transfer of symbionts to particular host lineages and populations of related hosts. Using reciprocal transfections of the facultative symbiont Hamiltonella defensa into different pea aphid clones, we demonstrate that particular symbiont strains can cause high host mortality and inhibit offspring production when injected into aphid clones other than their native host lineage. However, once established, the symbiont's ability to protect against parasitoids was not influenced by its origin. We then demonstrate that H. defensa is also more likely to establish a symbiotic relationship with aphid clones from a plant-adapted population (biotype) that typically carry H. defensa in nature, compared to clones from a biotype that does not normally carry this symbiont. These results provide evidence that certain aphid lineages and populations of related hosts are predisposed to establishing a symbiotic relationship with H. defensa. Our results demonstrate that host-symbiont genotype interactions represent a potential barrier to horizontal transmission that can limit the spread of symbionts, and adaptive traits they carry, to certain host lineages.

Image-Based Virtual Tours and 3d Modeling of Past and Current Ages for the Enhancement of Archaeological Parks: the Visualversilia 3d Project

NASA Astrophysics Data System (ADS)

Castagnetti, C.; Giannini, M.; Rivola, R.

2017-05-01

The research project VisualVersilia 3D aims at offering a new way to promote the territory and its heritage by matching the traditional reading of the document and the potential use of modern communication technologies for the cultural tourism. Recently, the research on the use of new technologies applied to cultural heritage have turned their attention mainly to technologies to reconstruct and narrate the complexity of the territory and its heritage, including 3D scanning, 3D printing and augmented reality. Some museums and archaeological sites already exploit the potential of digital tools to preserve and spread their heritage but interactive services involving tourists in an immersive and more modern experience are still rare. The innovation of the project consists in the development of a methodology for documenting current and past historical ages and integrating their 3D visualizations with rendering capable of returning an immersive virtual reality for a successful enhancement of the heritage. The project implements the methodology in the archaeological complex of Massaciuccoli, one of the best preserved roman site of the Versilia Area (Tuscany, Italy). The activities of the project briefly consist in developing: 1. the virtual tour of the site in its current configuration on the basis of spherical images then enhanced by texts, graphics and audio guides in order to enable both an immersive and remote tourist experience; 2. 3D reconstruction of the evidences and buildings in their current condition for documentation and conservation purposes on the basis of a complete metric survey carried out through laser scanning; 3. 3D virtual reconstructions through the main historical periods on the basis of historical investigation and the analysis of data acquired.

Low-Energy Electron Potentiometry: Contactless Imaging of Charge Transport on the Nanoscale.

PubMed

Kautz, J; Jobst, J; Sorger, C; Tromp, R M; Weber, H B; van der Molen, S J

2015-09-04

Charge transport measurements form an essential tool in condensed matter physics. The usual approach is to contact a sample by two or four probes, measure the resistance and derive the resistivity, assuming homogeneity within the sample. A more thorough understanding, however, requires knowledge of local resistivity variations. Spatially resolved information is particularly important when studying novel materials like topological insulators, where the current is localized at the edges, or quasi-two-dimensional (2D) systems, where small-scale variations can determine global properties. Here, we demonstrate a new method to determine spatially-resolved voltage maps of current-carrying samples. This technique is based on low-energy electron microscopy (LEEM) and is therefore quick and non-invasive. It makes use of resonance-induced contrast, which strongly depends on the local potential. We demonstrate our method using single to triple layer graphene. However, it is straightforwardly extendable to other quasi-2D systems, most prominently to the upcoming class of layered van der Waals materials.

ECR ion source with electron gun

DOEpatents

Xie, Z.Q.; Lyneis, C.M.

1993-10-26

An Advanced Electron Cyclotron Resonance ion source having an electron gun for introducing electrons into the plasma chamber of the ion source is described. The ion source has a injection enclosure and a plasma chamber tank. The plasma chamber is defined by a plurality of longitudinal magnets. The electron gun injects electrons axially into the plasma chamber such that ionization within the plasma chamber occurs in the presence of the additional electrons produced by the electron gun. The electron gun has a cathode for emitting electrons therefrom which is heated by current supplied from an AC power supply while bias potential is provided by a bias power supply. A concentric inner conductor and outer conductor carry heating current to a carbon chuck and carbon pusher which hold the cathode in place and also heat the cathode. In the Advanced Electron Cyclotron Resonance ion source, the electron gun replaces the conventional first stage used in prior electron cyclotron resonance ion generators. 5 figures.

Active treatment for food allergy.

PubMed

Kobernick, Aaron K; Burks, A Wesley

2016-10-01

Food allergy has grown in rapidly in prevalence, currently affecting 5% of adults and 8% of children. Management strategy is currently limited to 1) food avoidance and 2) carrying and using rescue intramuscular epinephrine/adrenaline and oral antihistamines in the case of accidental ingestion; there is no FDA approved treatment. Recently, oral, sublingual and epicutaneous immunotherapy have been developed as active treatment of food allergy, though none have completed phase 3 study. Efficacy and safety studies of immunotherapy have been variable, though there is clearly signal that immunotherapy will be a viable option to desensitize patients. The use of bacterial adjuvants, anti-IgE monoclonal antibodies, and Chinese herbal formulations either alone or in addition to immunotherapy may hold promise as future options for active treatment. Active prevention of food allergy through early introduction of potentially offending foods in high-risk infants will be an important means to slow the rising incidence of sensitization. Copyright © 2016 Japanese Society of Allergology. Production and hosting by Elsevier B.V. All rights reserved.

On the applicability of the Natori formula to realistic multi-layer quantum well III-V FETs

NASA Astrophysics Data System (ADS)

Gili, A.; Xanthakis, J. P.

2017-10-01

We investigated the validity of the Natori formalism for realistic multi-layer quantum well FETs. We show that the assumption of a single layer (the channel) carrying all of the current density is far from reality in the sub-threshold region, where in fact most of the current density resides below the channel. Our analysis is based on comparing results of Natori calculations with experimental ones and on comparing with other first-principles calculations. If the Natori calculations are employed in the subthreshold region then a misleadingly small subthreshold slope would be obtained. We propose a way to remedy this inefficiency of this formulation so that it can be applicable to realistic many-layer devices. In particular we show that if the 1-dimensional quantum well of the Natori method enclosing the electron gas is expanded to include the supply layer-usually below the channel- and a proper ab initio potential is used to obtain its eigenvalues, then the Natori formula regains its validity.

Results from a tethered rocket experiment (Charge-2)

NASA Astrophysics Data System (ADS)

Kawashima, N.; Sasaki, S.; Oyama, K. I.; Hirao, K.; Obayashi, T.; Raitt, W. J.; White, A. B.; Williamson, P. R.; Banks, P. M.; Sharp, W. F.

A tethered payload experiment (Charge-2) was carried out as an international program between Japan and the USA using a NASA sounding rocket at White Sands Missile Range. The objective of the experiment was to perform a new type of active experiment in space by injecting an electron beam from a mother-daughter rocket system connected with a long tether wire. The electron beam with voltage and current up to 1 kV and 80 mA (nominal) was injected from the mother payload. An insulated conductive wire of 426 m length connected the two payloads, the longest tether system flown so far. The electron gun system and diagnostic instruments (plasma, optical, particle and wave) functioned correctly throughout the flight. The potential rise of the mother payload during the electron beam emission was measured with respect to the daughter payload. The beam trajectory was detected by a camera onboard the mother rocket. Wave generation and current induction in the wire during the beam emission were also studied.

Consolidation of Partially Stabilized ZrO2 in the Presence of a Noncontacting Electric Field

NASA Astrophysics Data System (ADS)

Majidi, Hasti; van Benthem, Klaus

2015-05-01

Electric field-assisted sintering techniques demonstrate accelerated densification at lower temperatures than the conventional sintering methods. However, it is still debated whether the applied field and/or resulting currents are responsible for the densification enhancement. To distinguish the effects of an applied field from current flow, in situ scanning transmission electron microscopy experiments with soft agglomerates of partially stabilized yttria-doped zirconia particles are carried out. A new microelectromechanical system-based sample support is used to heat particle agglomerates while simultaneously exposing them to an externally applied noncontacting electric field. Under isothermal condition at 900 °C , an electric field strength of 500 V /cm shows a sudden threefold enhancement in the shrinkage of the agglomerates. The applied electrostatic potential lowers the activation energy for point defect formation within the space charge zone and therefore promotes consolidation. Obtaining similar magnitudes of shrinkage in the absence of any electric field requires a higher temperature and longer time.

Current understanding of auditory neuropathy.

PubMed

Boo, Nem-Yun

2008-12-01

Auditory neuropathy is defined by the presence of normal evoked otoacoustic emissions (OAE) and absent or abnormal auditory brainstem responses (ABR). The sites of lesion could be at the cochlear inner hair cells, spiral ganglion cells of the cochlea, synapse between the inner hair cells and auditory nerve, or the auditory nerve itself. Genetic, infectious or neonatal/perinatal insults are the 3 most commonly identified underlying causes. Children usually present with delay in speech and language development while adult patients present with hearing loss and disproportionately poor speech discrimination for the degree of hearing loss. Although cochlear implant is the treatment of choice, current evidence show that it benefits only those patients with endocochlear lesions, but not those with cochlear nerve deficiency or central nervous system disorders. As auditory neuropathy is a disorder with potential long-term impact on a child's development, early hearing screen using both OAE and ABR should be carried out on all newborns and infants to allow early detection and intervention.

Bioremediation of waste under ocean acidification: Reviewing the role of Mytilus edulis.

PubMed

Broszeit, Stefanie; Hattam, Caroline; Beaumont, Nicola

2016-02-15

Waste bioremediation is a key regulating ecosystem service, removing wastes from ecosystems through storage, burial and recycling. The bivalve Mytilus edulis is an important contributor to this service, and is used in managing eutrophic waters. Studies show that they are affected by changes in pH due to ocean acidification, reducing their growth. This is forecasted to lead to reductions in M. edulis biomass of up to 50% by 2100. Growth reduction will negatively affect the filtering capacity of each individual, potentially leading to a decrease in bioremediation of waste. This paper critically reviews the current state of knowledge of bioremediation of waste carried out by M. edulis, and the current knowledge of the resultant effect of ocean acidification on this key service. We show that the effects of ocean acidification on waste bioremediation could be a major issue and pave the way for empirical studies of the topic. Copyright © 2016 Elsevier Ltd. All rights reserved.

Literature Survey of Crude Oil Properties Relevant to Handling and Fire Safety in Transport.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lord, David; Luketa, Anay; Wocken, Chad

2015-03-01

Several fiery rail accidents in 2013-2015 in the U.S. and Canada carrying crude oil produced from the Bakken region of North Dakota have raised questions at many levels on the safety of transporting this, and other types of crude oil, by rail. Sandia National Laboratories was commissioned by the U.S. Department of Energy to investigate the material properties of crude oils, and in particular the so-called "tight oils" like Bakken that comprise the majority of crude oil rail shipments in the U.S. at the current time. The current report is a literature survey of public sources of information on crudemore » oil properties that have some bearing on the likelihood or severity of combustion events that may occur around spills associated with rail transport. The report also contains background information including a review of the notional "tight oil" field operating environment, as well a basic description of crude oils and potential combustion events in rail transport. This page intentionally blank« less

Corrosion Behavior of Cast Iron in Freely Aerated Stagnant Arabian Gulf Seawater

PubMed Central

Sherif, El-Sayed M.; Abdo, Hany S.; Almajid, Abdulhakim A.

2015-01-01

In this work, the results obtained from studying the corrosion of cast iron in freely aerated stagnant Arabian Gulf seawater (AGS) at room temperature were reported. The study was carried out using weight-loss (WL), cyclic potentiodynamic polarization (CPP), open-circuit potential (OCP), and electrochemical impedance spectroscopy (EIS) measurements and complemented by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) investigations. WL experiments between two and 10 days’ immersion in the test electrolyte indicated that the weight-loss the cast iron increases with increasing the time of immersion. CPP measurements after 1 h and 24 h exposure period showed that the increase of time decreases the corrosion via decreasing the anodic and cathodic currents, as well as decreasing the corrosion current and corrosion rate and increasing the polarization resistance of the cast iron. EIS data confirmed the ones obtained by WL and CPP that the increase of immersion time decreases the corrosion of cast iron by increasing its polarization resistance.

A review of research on the environmental impact of e-business and ICT.

PubMed

Yi, Lan; Thomas, Hywel R

2007-08-01

This paper attempts to provide a review of the current state of the art of how e-business/ICT affects the environment. The work reviewed is in various forms including journal papers and thesis which have been peer-reviewed, as well as other resources such as projects and project reports, conference and symposia, and websites. It is claimed that the research examined has captured the most important work to date, either for a general knowledge of this new area or for background study by experts carrying out future research. The review has found that the currently dominant approach is either a micro-level case study approach or a macro-level statistical approach. It is concluded that a more predictive and empirical model, which can be applied within a sector of society, should be more beneficial in the long term. This approach should help simulate potential impacts resulting from changes of indicators, so that positive effects can be promoted and negative ones alleviated proactively, rather than knowing and accepting outcomes passively.

Three dimensional instabilities of an electron scale current sheet in collisionless magnetic reconnection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jain, Neeraj; Büchner, Jörg; Max Planck Institute for Solar System Research, Justus-Von-Liebig-Weg-3, Göttingen

In collisionless magnetic reconnection, electron current sheets (ECS) with thickness of the order of an electron inertial length form embedded inside ion current sheets with thickness of the order of an ion inertial length. These ECS's are susceptible to a variety of instabilities which have the potential to affect the reconnection rate and/or the structure of reconnection. We carry out a three dimensional linear eigen mode stability analysis of electron shear flow driven instabilities of an electron scale current sheet using an electron-magnetohydrodynamic plasma model. The linear growth rate of the fastest unstable mode was found to drop with themore » thickness of the ECS. We show how the nature of the instability depends on the thickness of the ECS. As long as the half-thickness of the ECS is close to the electron inertial length, the fastest instability is that of a translational symmetric two-dimensional (no variations along flow direction) tearing mode. For an ECS half thickness sufficiently larger or smaller than the electron inertial length, the fastest mode is not a tearing mode any more and may have finite variations along the flow direction. Therefore, the generation of plasmoids in a nonlinear evolution of ECS is likely only when the half-thickness is close to an electron inertial length.« less

Enhancement of anodic current attributed to oxygen evolution on α-Fe2O3 electrode by microwave oscillating electric field

PubMed Central

Kishimoto, Fuminao; Matsuhisa, Masayuki; Kawamura, Shinichiro; Fujii, Satoshi; Tsubaki, Shuntaro; Maitani, Masato M.; Suzuki, Eiichi; Wada, Yuji

2016-01-01

Various microwave effects on chemical reactions have been observed, reported and compared to those carried out under conventional heating. These effects are classified into thermal effects, which arise from the temperature rise caused by microwaves, and non-thermal effects, which are attributed to interactions between substances and the oscillating electromagnetic fields of microwaves. However, there have been no direct or intrinsic demonstrations of the non-thermal effects based on physical insights. Here we demonstrate the microwave enhancement of oxidation current of water to generate dioxygen with using an α-Fe2O3 electrode induced by pulsed microwave irradiation under constantly applied potential. The rectangular waves of current density under pulsed microwave irradiation were observed, in other words the oxidation current of water was increased instantaneously at the moment of the introduction of microwaves, and stayed stably at the plateau under continuous microwave irradiation. The microwave enhancement was observed only for the α-Fe2O3 electrode with the specific surface electronic structure evaluated by electrochemical impedance spectroscopy. This discovery provides a firm evidence of the microwave special non-thermal effect on the electron transfer reactions caused by interaction of oscillating microwaves and irradiated samples. PMID:27739529

Ion Traps at the Sun: Implications for Elemental Fractionation

NASA Astrophysics Data System (ADS)

Fleishman, Gregory D.; Musset, Sophie; Bommier, Véronique; Glesener, Lindsay

2018-04-01

Why the tenuous solar outer atmosphere, or corona, is much hotter than the underlying layers remains one of the greatest challenges for solar modeling. Detailed diagnostics of the coronal thermal structure come from extreme ultraviolet (EUV) emission. The EUV emission is produced by heavy ions in various ionization states and depends on the amount of these ions and on plasma temperature and density. Any nonuniformity of the elemental distribution in space or variability in time affects thermal diagnostics of the corona. Here we theoretically predict ionized chemical element concentrations in some areas of the solar atmosphere, where the electric current is directed upward. We then detect these areas observationally, by comparing the electric current density with the EUV brightness in an active region. We found a significant excess in EUV brightness in the areas with positive current density rather than negative. Therefore, we report the observational discovery of substantial concentrations of heavy ions in current-carrying magnetic flux tubes, which might have important implications for the elemental fractionation in the solar corona known as the first ionization potential effect. We call such areas of heavy ion concentration the “ion traps.” These traps hold enhanced ion levels until they are disrupted by a flare, whether large or small.

Algebraic motion of vertically displacing plasmas

NASA Astrophysics Data System (ADS)

Bhattacharjee, Amitava; Pfefferle, David; Hirvijoki, Eero

2017-10-01

The vertical displacement of tokamak plasmas is modelled during the non-linear phase by a free-moving current-carrying rod coupled to a set of fixed conducting wires and a cylindrical conducting shell. The models capture the leading term in a Taylor expansion of the Green's function for the interaction between the plasma column and the vacuum vessel. The plasma is assumed not to vary during the VDE such that it behaves as a rigid body. In the limit of perfectly conducting structures, the plasma is prevented from coming in contact with the wall due to steep effective potential barriers by the eddy currents, and will hence oscillate at Alfvénic frequencies about a given force-free position. In addition to damping oscillations, resistivity allows for the column to drift towards the vessel on slow flux penetration timescales. The initial exponential motion of the plasma, i.e. the resistive vertical instability, is succeeded by a non-linear sinking behaviour, that is shown analytically to be algebraic and decelerative. The acceleration of the plasma column often observed in experiments is thus conjectured to originate from an early sharing of toroidal current between the core, the halo plasma and the wall or from the thermal quench dynamics precipitating loss of plasma current

Algebraic motion of vertically displacing plasmas

DOE PAGES

Pfefferle, D.; Bhattacharjee, A.

2018-02-27

In this paper, the vertical motion of a tokamak plasma is analytically modelled during its non-linear phase by a free-moving current-carrying rod inductively coupled to a set of fixed conducting wires or a cylindrical conducting shell. The solutions capture the leading term in a Taylor expansion of the Green's function for the interaction between the plasma column and the surrounding vacuum vessel. The plasma shape and profiles are assumed not to vary during the vertical drifting phase such that the plasma column behaves as a rigid body. In the limit of perfectly conducting structures, the plasma is prevented to comemore » in contact with the wall due to steep effective potential barriers created by the induced Eddy currents. Resistivity in the wall allows the equilibrium point to drift towards the vessel on the slow timescale of flux penetration. The initial exponential motion of the plasma, understood as a resistive vertical instability, is succeeded by a non-linear “sinking” behaviour shown to be algebraic and decelerating. Finally, the acceleration of the plasma column often observed in experiments is thus concluded to originate from an early sharing of toroidal current between the core, the halo plasma, and the wall or from the thermal quench dynamics precipitating loss of plasma current.« less

Osteosarcoma Overview.

PubMed

Lindsey, Brock A; Markel, Justin E; Kleinerman, Eugenie S

2017-06-01

Osteosarcoma (OS) is the most common primary malignancy of bone and patients with metastatic disease or recurrences continue to have very poor outcomes. Unfortunately, little prognostic improvement has been generated from the last 20 years of research and a new perspective is warranted. OS is extremely heterogeneous in both its origins and manifestations. Although multiple associations have been made between the development of osteosarcoma and race, gender, age, various genomic alterations, and exposure situations among others, the etiology remains unclear and controversial. Noninvasive diagnostic methods include serum markers like alkaline phosphatase and a growing variety of imaging techniques including X-ray, computed tomography, magnetic resonance imaging, and positron emission as well as combinations thereof. Still, biopsy and microscopic examination are required to confirm the diagnosis and carry additional prognostic implications such as subtype classification and histological response to neoadjuvant chemotherapy. The current standard of care combines surgical and chemotherapeutic techniques, with a multitude of experimental biologics and small molecules currently in development and some in clinical trial phases. In this review, in addition to summarizing the current understanding of OS etiology, diagnostic methods, and the current standard of care, our group describes various experimental therapeutics and provides evidence to encourage a potential paradigm shift toward the introduction of immunomodulation, which may offer a more comprehensive approach to battling cancer pleomorphism.

Algebraic motion of vertically displacing plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pfefferle, D.; Bhattacharjee, A.

In this paper, the vertical motion of a tokamak plasma is analytically modelled during its non-linear phase by a free-moving current-carrying rod inductively coupled to a set of fixed conducting wires or a cylindrical conducting shell. The solutions capture the leading term in a Taylor expansion of the Green's function for the interaction between the plasma column and the surrounding vacuum vessel. The plasma shape and profiles are assumed not to vary during the vertical drifting phase such that the plasma column behaves as a rigid body. In the limit of perfectly conducting structures, the plasma is prevented to comemore » in contact with the wall due to steep effective potential barriers created by the induced Eddy currents. Resistivity in the wall allows the equilibrium point to drift towards the vessel on the slow timescale of flux penetration. The initial exponential motion of the plasma, understood as a resistive vertical instability, is succeeded by a non-linear “sinking” behaviour shown to be algebraic and decelerating. Finally, the acceleration of the plasma column often observed in experiments is thus concluded to originate from an early sharing of toroidal current between the core, the halo plasma, and the wall or from the thermal quench dynamics precipitating loss of plasma current.« less

Terbinafine is a novel and selective activator of the two-pore domain potassium channel TASK3.

PubMed

Wright, Paul D; Veale, Emma L; McCoull, David; Tickle, David C; Large, Jonathan M; Ococks, Emma; Gothard, Gemma; Kettleborough, Catherine; Mathie, Alistair; Jerman, Jeffrey

2017-11-04

Two-pore domain potassium channels (K2Ps) are characterized by their four transmembrane domain and two-pore topology. They carry background (or leak) potassium current in a variety of cell types. Despite a number of important roles there is currently a lack of pharmacological tools with which to further probe K2P function. We have developed a cell-based thallium flux assay, using baculovirus delivered TASK3 (TWIK-related acid-sensitive K + channel 3, KCNK9, K2P9.1) with the aim of identifying novel, selective TASK3 activators. After screening a library of 1000 compounds, including drug-like and FDA approved molecules, we identified Terbinafine as an activator of TASK3. In a thallium flux assay a pEC50 of 6.2 ( ±0.12) was observed. When Terbinafine was screened against TASK2, TREK2, THIK1, TWIK1 and TRESK no activation was observed in thallium flux assays. Several analogues of Terbinafine were also purchased and structure activity relationships examined. To confirm Terbinafine's activation of TASK3 whole cell patch clamp electrophysiology was carried out and clear potentiation observed in both the wild type channel and the pathophysiological, Birk-Barel syndrome associated, G236R TASK3 mutant. No activity at TASK1 was observed in electrophysiology studies. In conclusion, we have identified the first selective activator of the two-pore domain potassium channel TASK3. Copyright © 2017 Elsevier Inc. All rights reserved.

[News in cystic fibrosis].

PubMed

Delaisi, B

2013-08-01

The improvement over the last two decades in the treatment of cystic fibrosis led to an increase in life expectancy approaching 40 years at birth. Logically, the population of adult patients has been increasing and is currently 50% of patients followed in France. These therapeutic advances have justified the establishment in 2003 of a generalized neonatal screening for cystic fibrosis. The latest data of this screening show an incidence of CF of 1/5359 live births, far below the incidence of 1/2500 which was widely accepted twenty years ago. The performance of this screening is currently based on the dosage of trypsin immuno reactive, followed in case of exceeding the threshold of a search of the 30 most common mutations, can detect around 96% of 150 to 200 CF cases every year. Therefore, the possibility of a false negative of the screening cannot be excluded and evocative symptoms of cystic fibrosis, even for children born after 2003, will lead to prescribe a sweat test. While treatments available so far goal consequences of cystic fibrosis, a new therapeutic class to correct the functional defect of the mutated protein, called CFTR modulators, is emerging. Ivacaftor, leader of this new class, belonging to the category of "CFTR potentiator" got its access on the market in September 2012 for patients carrying the G551D mutation. New other molecules, named "CFTR correctors" which can have synergistic effect with ivacaftor and concern patients carrying the most common mutation--DF 508--are under development. Copyright © 2013. Published by Elsevier Masson SAS.

Neutralization of bactericidal activity related to antimicrobial carry-over in broiler carcass rinse samples

USDA-ARS?s Scientific Manuscript database

Chemical antimicrobial interventions used as poultry processing aids may have potential for carry-over into whole poultry carcass buffered peptone water (BPW) rinses collected for the recovery of viable Salmonella. Such carry-over may lead to false negative indications due to continuing bactericidal...

Simultaneous measurements of ion and electron currents using a novel compact electrostatic end-loss-current detector

NASA Astrophysics Data System (ADS)

Hirata, M.; Miyake, Y.; Cho, T.; Kohagura, J.; Numakura, T.; Shimizu, K.; Ito, M.; Kiminami, S.; Morimoto, N.; Hirai, K.; Yamagishi, T.; Miyata, Y.; Nakashima, Y.; Miyoshi, S.; Ogura, K.; Kondoh, T.; Kariya, T.

2006-10-01

For the purpose of end-loss-ion and -electron analyses in open-field plasmas, a compact-sized electrostatic end-loss-current detector is proposed on the basis of a self-collection principle for suppressing the effects of secondary-electron emission from a metal collector. For employing this specific method, it is worth noting that no further additional magnetic systems except the ambient open-ended magnetic fields are required in the detector operation. This characteristic property provides a compactness of the total detection system and availability for its use in plasma confinement devices without disturbing plasma-confining magnetic fields. The detector consists of a set of parallel metal plates with respect to lines of ambient magnetic forces of a plasma device for analyzing incident ion currents along with a grid for shielding the collector against strays due to the metal-plate biasing. The characterization experiments are carried out by the use of a test-ion-beam line along with an additional use of a Helmholtz coil system for the formation of open magnetic fields similar to those in the GAMMA 10 end region. The applications of the developed end-loss-current detector in the GAMMA 10 plasma experiments are demonstrated under the conditions with simultaneous incidence of energetic electrons produced by electron-cyclotron heatings for end-loss-plugging potential formation.

Overcoming limits set by scarce resources - role of local food production and food imports

NASA Astrophysics Data System (ADS)

Porkka, Miina; Guillaume, Joseph H. A.; Schaphoff, Sibyll; Siebert, Stefan; Gerten, Dieter; Kummu, Matti

2017-04-01

There is a fundamental tension between population growth and carrying capacity, i.e. the population that could potentially be supported using the resources and technologies available at a given time. This makes the assessments of resource use and agricultural productivity central to the debate on future food security. Local carrying capacity can be increased by expanding (e.g. through land conversion and irrigation infrastructure) or intensifying (e.g. through technologies and practices that increase efficiency) the resource use in agriculture. Food imports can be considered another way of overcoming current local limits and continuing growth beyond the local human-carrying capacity. Focusing on water as the key limiting resource, we performed a global assessment of the capacity for food self-sufficiency at sub-national and national scale for 1961-2009, taking into account the availability of both green and blue water as well as technology and management practices affecting water productivity at a given time, and using the hydrology and agriculture model LPJmL as our primary tool. Furthermore, we examined the use of food imports as a strategy to increase carrying capacity in regions where the potential for food self-sufficiency was limited by water availability and productivity. We found that the capacity for food self-sufficiency reduced notably during the study period due to the rapid population growth that outpaced the substantial improvements in water productivity. In 2009 more than a third (2.2 billion people) of the world's population lived in areas where sufficient food production to meet the needs of the population was not possible, and some 800 million people more were approaching this threshold. Food imports have nearly universally been used to overcome these local limits to growth, though the success of this strategy has been highly dependent on economic purchasing power. In the unsuccessful cases, increases in imports and local productivity have not kept pace with population growth, leaving 460 million people with insufficient food. Where the strategy has been successful, food security of 1.4 billion people has become dependent on imports. Whether or not this dependence on imports is considered desirable, it has policy implications that need to be taken into account.

Environmental impact studies for gas hydrate production test in the Ulleung Basin, East Sea of Korea

NASA Astrophysics Data System (ADS)

Ryu, Byong-Jae

2017-04-01

To develop potential future energy resources, the Korean National Gas Hydrate Program has been carried out since 2005. The program has been supported by the Ministry of Trade, Industry and Energy (MOTIE), and carried out by the Korea Institute of Geoscience and Mineral Resources (KIGAM), the Korea Gas Corporation (KOGAS) and the Korea National Oil Corporation (KNOC) under the management of Gas Hydrate R&D Organization (GHDO). As a part of this national program, geophysical surveys, geological studies on gas hydrates and two deep drilling expeditions were performed. Gas hydrate-bearing sand layers suitable for production using current technologies were found during the Second Ulleung Basin Gas Hydrate Drilling Expedition (UBGH2) in 2010. Environmental impact studies (EIS) also have been carried out since 2012 by KIGAM in cooperation with domestic and foreign universities and research organizations to ensure safe production test that will be performed in near future. The schedule of production test is being planned. The EIS includes assessment of environmental risks, examination on domestic environmental laws related with production test, collection of basic oceanographic information, and baseline and monitoring surveys. Oceanographic information and domestic environmental laws are already collected and analyzed. Baseline survey has been performed using the in-house developed system, KIGAM Seafloor Observation System (KISOS) since 2013. It will also be performed. R/V TAMHAE II of KIGAM used for KISOS operation. As a part of this EIS, pseudo-3D Chirp survey also was carried out in 2014 to determine the development of fault near the potential testing site. Using KIGAM Seafloor Monitoring System (KIMOS), monitoring survey is planned to be performed from three month before production test to three months after production test. The geophysical survey for determining the change of gas hydrate reservoirs and production-efficiency around the production well would also be conducted before and after the production test. KIMOS will be developed as the planning that was drawn up already. A period for monitoring survey and geophysical survey type, such as AUV or EM surveys will be decided according to the budget.

The analysis of the quality of the frequency control of induction motor carried out on the basis of the processes in the rotor circuit

NASA Astrophysics Data System (ADS)

Kodkin, V. L.; Anikin, A. S.; Baldenkov, A. A.

2018-01-01

The results of researches of asynchronous electric drives with the frequency control which are carried out for the purpose of establishment of causes and effect relationships between a control method, the implementable standard frequency converter of the Schneider Electric company (ATV-71, ATV-32) and its efficiency are given in article. Tests with asynchronous motors with wound rotor were for the first time carried out. It allowed registering during the experiments the instantaneous values not only the stator currents, but also rotor currents. Authors for the first time applied spectrum analysis of stator and rotor currents, it showed that «sensorless vector» control leads to origin of high-frequency harmonicas with the considerable amplitude and, as a result of they are non-sinusoidal of the created torque and inefficiency of the electric drive. The accelerations that are carried out during the researches to 94, 157 and 251 Rad/s confirmed this feature of vector control that appears incapable to linearize the asynchronous electric drive as it was supposed authors of a method. These results do not contradict theoretical provisions if not to neglect assumptions which usually become in case of an output of the equations of vector control. Unfortunately, the modern researchers do not subject these assumptions to doubts. Continued studies make it possible to create an effective frequency management of asynchronous electric drives required for current technology.

A current-carrying coil design with improved liquid cooling arrangement

NASA Astrophysics Data System (ADS)

Ricci, Leonardo; Martini, Luca Matteo; Franchi, Matteo; Bertoldi, Andrea

2013-06-01

The design of an electromagnet requires the compliance with a number of constraints such as power supply characteristics, coil inductance and resistance, and, above all, heat dissipation, which poses the limit to the maximum achievable magnetic field. A common solution consists in using copper tubes in which a coolant flows. This approach, however, introduces further hydrodynamic concerns. To overcome these difficulties, we developed a new kind of electromagnet in which the pipe concept is replaced by a duct formed by the windings. Here we report on the realization and characterization of a compact model system in which the conductors carry a current that is one order of magnitude higher than the current allowable with conventional designs.

Comparison of permutationally invariant polynomials, neural networks, and Gaussian approximation potentials in representing water interactions through many-body expansions

NASA Astrophysics Data System (ADS)

Nguyen, Thuong T.; Székely, Eszter; Imbalzano, Giulio; Behler, Jörg; Csányi, Gábor; Ceriotti, Michele; Götz, Andreas W.; Paesani, Francesco

2018-06-01

The accurate representation of multidimensional potential energy surfaces is a necessary requirement for realistic computer simulations of molecular systems. The continued increase in computer power accompanied by advances in correlated electronic structure methods nowadays enables routine calculations of accurate interaction energies for small systems, which can then be used as references for the development of analytical potential energy functions (PEFs) rigorously derived from many-body (MB) expansions. Building on the accuracy of the MB-pol many-body PEF, we investigate here the performance of permutationally invariant polynomials (PIPs), neural networks, and Gaussian approximation potentials (GAPs) in representing water two-body and three-body interaction energies, denoting the resulting potentials PIP-MB-pol, Behler-Parrinello neural network-MB-pol, and GAP-MB-pol, respectively. Our analysis shows that all three analytical representations exhibit similar levels of accuracy in reproducing both two-body and three-body reference data as well as interaction energies of small water clusters obtained from calculations carried out at the coupled cluster level of theory, the current gold standard for chemical accuracy. These results demonstrate the synergy between interatomic potentials formulated in terms of a many-body expansion, such as MB-pol, that are physically sound and transferable, and machine-learning techniques that provide a flexible framework to approximate the short-range interaction energy terms.

Investigation on the Characteristics of Pellet Ablation in a Toroidal Plasma

NASA Astrophysics Data System (ADS)

Sato, K. N.; Sakakita, H.; Fujita, H.

2003-06-01

Characteristics of a cloud ablated from an ice pellet has been investigated in detail in the JIPP T-IIU tokamak plasma by utilizing a new scheme of pellet injection system, "the injection-angle controllable system". A long "helical tail" of ablation light has been observed using CCD cameras and a high speed framing photograph in the case of on-axis and off-axis injection with the injection angle smaller than a certain value. The direction of the helical tail is found to be independent to that of the total magnetic field lines of the torus. From the experiments with the combination of two toroildal filed directions and two plasma current directions, it is considered that the tail seems to rotate, in most cases, to the electron diamagnetic direction poloidally, and to the opposite to the plasma current direction toroidally. Consideration on various cross sections including charge exchange, ionization and elastic collisions leads us to the conclusion that the tail-shaped phenomena may come from the situation of charge exchange equilibrium of hydrogen ions and neutrals at extremely high density regime in the cloud. The relation of ablation behavior with plasma potential and rotation has also been studied. Potential measurements of pellet-injected plasmas using heavy ion beam probe (HIBP) method were carried out for the first time. In the case of an injection angle to be anti-parallel to the electron diamagnetic direction in the poloidal plane, the result shows that the direction of potential change is negative, and consequently the potential after the injection should be negative because it has been measured to be negative in usual ohmic plasmas without pellet injection. Thus, the direction of the "tail" structure seems to be consistent to that of the plasma potential measured, if it is considered that tail structure may be caused by the effect of the plasma potential and the rotation.

Acid-Sensing Ion Channels Expression, Identity and Role in the Excitability of the Cochlear Afferent Neurons

PubMed Central

González-Garrido, Antonia; Vega, Rosario; Mercado, Francisco; López, Iván A.; Soto, Enrique

2015-01-01

Acid-sensing ion channels (ASICs) are activated by an increase in the extracellular proton concentration. There are four genes (ASIC1-4) that encode six subunits, and they are involved in diverse neuronal functions, such as mechanosensation, learning and memory, nociception, and modulation of retinal function. In this study, we characterize the ASIC currents of spiral ganglion neurons (SGNs). These ASIC currents are primarily carried by Na+, exhibit fast activation and desensitization, display a pH50 of 6.2 and are blocked by amiloride, indicating that these are ASIC currents. The ASIC currents were further characterized using several pharmacological tools. Gadolinium and acetylsalicylic acid reduced these currents, and FMRFamide, zinc (at high concentrations) and N,N,N’,N’–tetrakis-(2-piridilmetil)-ethylenediamine increased them, indicating that functional ASICs are composed of the subunits ASIC1, ASIC2, and ASIC3. Neomycin and streptomycin reduced the desensitization rate of the ASIC current in SGNs, indicating that ASICs may contribute to the ototoxic action of aminoglycosides. RT-PCR of the spiral ganglion revealed significant expression of all ASIC subunits. By immunohistochemistry the expression of the ASIC1a, ASIC2a, ASIC2b, and ASIC3 subunits was detected in SGNs. Although only a few SGNs exhibited action potential firing in response to an acidic stimulus, protons in the extracellular solution modulated SGN activity during sinusoidal stimulation. Our results show that protons modulate the excitability of SGNs via ASICs. PMID:26733809

Revascularization for Left Main and Multivessel Coronary Artery Disease: Current Status and Future Prospects after the EXCEL and NOBLE Trials

PubMed Central

2018-01-01

Revascularization of severe left main and multivessel coronary artery disease has been shown to improve survival in both stable ischemic heart disease and acute coronary syndrome. While revascularization with coronary artery bypass surgery for these disease entities carries class I recommendation in most current guidelines, recent trials has shown potential comparable survival and cardiovascular outcomes between percutaneous and surgical interventions in patients with less complex coronary anatomy. Despite the conflicting results observed in the most recent left main revascularization trials, Everolimus-Eluting Stents or Bypass Surgery for Left Main Coronary Artery Disease (EXCEL) and Nordic-Baltic-British left main revascularization (NOBLE), both treatment strategies remain important for the management of left main disease (LMD) and multivessel disease (MVD) reflecting on the importance of heart team discussion. This review is focused on revascularization of LMD and MVD in patients who are not presenting with ST-segment elevation myocardial infarction, encompassing the evidence from historic and contemporary trials which shaped up current practices. This review discusses the heart team approach to guide decision making, including special populations that are not represented in clinical trials. PMID:29856140

Revascularization for Left Main and Multivessel Coronary Artery Disease: Current Status and Future Prospects after the EXCEL and NOBLE Trials.

PubMed

Al-Hijji, Mohammed; El Sabbagh, Abdallah; Holmes, David R

2018-06-01

Revascularization of severe left main and multivessel coronary artery disease has been shown to improve survival in both stable ischemic heart disease and acute coronary syndrome. While revascularization with coronary artery bypass surgery for these disease entities carries class I recommendation in most current guidelines, recent trials has shown potential comparable survival and cardiovascular outcomes between percutaneous and surgical interventions in patients with less complex coronary anatomy. Despite the conflicting results observed in the most recent left main revascularization trials, Everolimus-Eluting Stents or Bypass Surgery for Left Main Coronary Artery Disease (EXCEL) and Nordic-Baltic-British left main revascularization (NOBLE), both treatment strategies remain important for the management of left main disease (LMD) and multivessel disease (MVD) reflecting on the importance of heart team discussion. This review is focused on revascularization of LMD and MVD in patients who are not presenting with ST-segment elevation myocardial infarction, encompassing the evidence from historic and contemporary trials which shaped up current practices. This review discusses the heart team approach to guide decision making, including special populations that are not represented in clinical trials. Copyright © 2018. The Korean Society of Cardiology.

Critical current measurements of high-temperature superconducting short samples at a wide range of temperatures and magnetic fields.

PubMed

Ma, Hongjun; Liu, Huajun; Liu, Fang; Zhang, Huahui; Ci, Lu; Shi, Yi; Lei, Lei

2018-01-01

High-Temperature Superconductors (HTS) are potential materials for high-field magnets, low-loss transmission cables, and Superconducting Magnetic Energy Storage (SMES) due to their high upper critical magnetic field (H c2 ) and critical temperature (T c ). The critical current (I c ) of HTS, which is one of the most important parameters for superconductor application, depends strongly on the magnetic fields and temperatures. A new I c measurement system that can carry out accurate I c measurement for HTS short samples with various temperatures (4.2-80 K), magnetic fields (0-14 T), and angles of the magnetic field (0°-90°) has been developed. The I c measurement system mainly consists of a measurement holder, temperature-control system, background magnet, test cryostat, data acquisition system, and DC power supply. The accuracy of temperature control is better than ±0.1 K over the 20-80 K range and ±0.05 K when measured below 20 K. The maximum current is over 1000 A with a measurement uncertainty of 1%. The system had been successfully used for YBa 2 Cu 3 O 7-x (YBCO) tapes I c determination with different temperatures and magnetic fields.

Charge and current orders in the spin-fermion model with overlapping hot spots

NASA Astrophysics Data System (ADS)

Volkov, Pavel A.; Efetov, Konstantin B.

2018-04-01

Experiments carried over the last years on the underdoped cuprates have revealed a variety of symmetry-breaking phenomena in the pseudogap state. Charge-density waves, breaking of C4 rotational symmetry as well as time-reversal symmetry breaking have all been observed in several cuprate families. In this regard, theoretical models where multiple nonsuperconducting orders emerge are of particular interest. We consider the recently introduced [Volkov and Efetov, Phys. Rev. B 93, 085131 (2016), 10.1103/PhysRevB.93.085131] spin-fermion model with overlapping `hot spots' on the Fermi surface. Focusing on the particle-hole instabilities we obtain a rich phase diagram with the chemical potential relative to the dispersion at (0 ,π );(π ,0 ) and the Fermi surface curvature in the antinodal regions being the control parameters. We find evidence for d-wave Pomeranchuk instability, d-form factor charge density waves, as well as commensurate and incommensurate staggered bond current phases similar to the d-density wave state. The current orders are found to be promoted by the curvature. Considering the appropriate parameter range for the hole-doped cuprates, we discuss the relation of our results to the pseudogap state and incommensurate magnetic phases of the cuprates.

An undercurrent off the east coast of Sri Lanka

NASA Astrophysics Data System (ADS)

Anutaliya, Arachaporn; Send, Uwe; McClean, Julie L.; Sprintall, Janet; Rainville, Luc; Lee, Craig M.; Priyantha Jinadasa, S. U.; Wallcraft, Alan J.; Metzger, E. Joseph

2017-12-01

The existence of a seasonally varying undercurrent along 8° N off the east coast of Sri Lanka is inferred from shipboard hydrography, Argo floats, glider measurements, and two ocean general circulation model simulations. Together, they reveal an undercurrent below 100-200 m flowing in the opposite direction to the surface current, which is most pronounced during boreal spring and summer and switches direction between these two seasons. The volume transport of the undercurrent (200-1000 m layer) can be more than 10 Sv in either direction, exceeding the transport of 1-6 Sv carried by the surface current (0-200 m layer). The undercurrent transports relatively fresher water southward during spring, while it advects more saline water northward along the east coast of Sri Lanka during summer. Although the undercurrent is potentially a pathway of salt exchange between the Arabian Sea and the Bay of Bengal, the observations and the ocean general circulation models suggest that the salinity contrast between seasons and between the boundary current and interior is less than 0.09 in the subsurface layer, suggesting a small salt transport by the undercurrent of less than 4 % of the salinity deficit in the Bay of Bengal.

In vitro pharmacologic characterization of a cholinergic receptor on outer hair cells.

PubMed

Erostegui, C; Norris, C H; Bobbin, R P

1994-04-01

Acetylcholine (ACh) is the major neurotransmitter released from the efferent fibers in the cochlea onto the outer hair cells (OHCs). The type of ACh receptor on OHCs and the events subsequent to receptor activation are unclear. Therefore we studied the effect of agonists and antagonists of the ACh receptor on isolated OHCs from the guinea pig. OHCs were recorded from in whole cell voltage and current clamp configuration. ACh induced an increase in outward K+ current (IACh) which hyperpolarized the OHCs. No desensitization to ACh application was observed. Cs+ replaced K+ in carrying the IACh. The IACh is Ca(2+)-dependent, time and voltage sensitive, and different from the IKCa induced by depolarization of the membrane potential. When tested at 100 microM, several agonists also induced outward current responses (acetylcholine > suberyldicholine > or = carbachol > DMPP) whereas nicotine, cytisine and muscarine did not. The IACh response to 10 microM ACh was blocked by low concentrations of traditional and non-traditional-nicotinic antagonists (strychnine > curare > bicuculline > alpha-bungarotoxin > thimethaphan) and by higher concentrations of muscarinic antagonists (atropine > 4-DAMP > AF-DX 116 > pirenzepine). Pharmacologically, the ACh receptor on OHCs is nicotinic.

Critical current measurements of high-temperature superconducting short samples at a wide range of temperatures and magnetic fields

NASA Astrophysics Data System (ADS)

Ma, Hongjun; Liu, Huajun; Liu, Fang; Zhang, Huahui; Ci, Lu; Shi, Yi; Lei, Lei

2018-01-01

High-Temperature Superconductors (HTS) are potential materials for high-field magnets, low-loss transmission cables, and Superconducting Magnetic Energy Storage (SMES) due to their high upper critical magnetic field (Hc2) and critical temperature (Tc). The critical current (Ic) of HTS, which is one of the most important parameters for superconductor application, depends strongly on the magnetic fields and temperatures. A new Ic measurement system that can carry out accurate Ic measurement for HTS short samples with various temperatures (4.2-80 K), magnetic fields (0-14 T), and angles of the magnetic field (0°-90°) has been developed. The Ic measurement system mainly consists of a measurement holder, temperature-control system, background magnet, test cryostat, data acquisition system, and DC power supply. The accuracy of temperature control is better than ±0.1 K over the 20-80 K range and ±0.05 K when measured below 20 K. The maximum current is over 1000 A with a measurement uncertainty of 1%. The system had been successfully used for YBa2Cu3O7-x(YBCO) tapes Ic determination with different temperatures and magnetic fields.

Multidisciplinary oil spill modeling to protect coastal communities and the environment of the Eastern Mediterranean Sea

NASA Astrophysics Data System (ADS)

Alves, Tiago M.; Kokinou, Eleni; Zodiatis, George; Radhakrishnan, Hari; Panagiotakis, Costas; Lardner, Robin

2016-11-01

We present new mathematical and geological models to assist civil protection authorities in the mitigation of potential oil spill accidents in the Eastern Mediterranean Sea. Oil spill simulations for 19 existing offshore wells were carried out based on novel and high resolution bathymetric, meteorological, oceanographic, and geomorphological data. The simulations show a trend for east and northeast movement of oil spills into the Levantine Basin, affecting the coastal areas of Israel, Lebanon and Syria. Oil slicks will reach the coast in 1 to 20 days, driven by the action of the winds, currents and waves. By applying a qualitative analysis, seabed morphology is for the first time related to the direction of the oil slick expansion, as it is able to alter the movement of sea currents. Specifically, the direction of the major axis of the oil spills, in most of the cases examined, is oriented according to the prevailing azimuth of bathymetric features. This work suggests that oil spills in the Eastern Mediterranean Sea should be mitigated in the very few hours after their onset, and before wind and currents disperse them. We explain that protocols should be prioritized between neighboring countries to mitigate any oil spills.

Modeling of dynamic bipolar plasma sheaths

NASA Astrophysics Data System (ADS)

Grossmann, J. M.; Swanekamp, S. B.; Ottinger, P. F.

1991-08-01

The behavior of a one dimensional plasma sheath is described in regimes where the sheath is not in equilibrium because it carries current densities that are either time dependent, or larger than the bipolar Child-Langmuir level determined from the injected ion flux. Earlier models of dynamic bipolar sheaths assumed that ions and electrons evolve in a series of quasi-equilibria. In addition, sheath growth was described by the equation Zenoxs = (ji)-Zenouo, where xs is the velocity of the sheath edge, ji is the ion current density, nouo is the injected ion flux density, and Ze is the ion charge. In this paper, a generalization of the bipolar electron-to-ion current density ratio formula is derived to study regimes where ions are not in equilibrium. A generalization of the above sheath growth equation is also developed which is consistent with the ion continuity equation and which reveals new physics of sheath behavior associated with the emitted electrons and their evolution. Based on these findings, two new models of dynamic bipolar sheaths are developed. Larger sheath sizes and potentials than those of earlier models are found. In certain regimes, explosive sheath growth is predicted.

Force balance near an X line along which E x J is less than 0. [plasma transfer from closed to open field lines in geomagnetic tail

NASA Technical Reports Server (NTRS)

Lyons, L. R.; Pridmore-Brown, D. C.

1992-01-01

Conditions for which particle motion within the current sheet in the vicinity of an X line can give a current in the direction appropriate for E x J is less than 0. The way in which the balance between gyroviscosity and the electric force along an X line is maintained for any E x J is shown. It is concluded that observational evidence for the occasional existence of E x J is less than 0 along an X line provides support for the suggestion that collisionless graviscosity, rather than resistivity, balances the electric force along an X line. It is found that there is a maximum electric field magnitude for particles to be able to carry a significant current. For parameters typical of the distant magnetotail, the critical electric field magnitude was found to be about 0.15 mV/m, which is of the order of, though somewhat less than, the potential electric field magnitudes expected in the magnetotail. This maximum allowable field magnitude is about the same for protons as it is for electrons in the magnetotail.

Perspective for Aquaponic Systems: "Omic" Technologies for Microbial Community Analysis.

PubMed

Munguia-Fragozo, Perla; Alatorre-Jacome, Oscar; Rico-Garcia, Enrique; Torres-Pacheco, Irineo; Cruz-Hernandez, Andres; Ocampo-Velazquez, Rosalia V; Garcia-Trejo, Juan F; Guevara-Gonzalez, Ramon G

2015-01-01

Aquaponics is the combined production of aquaculture and hydroponics, connected by a water recirculation system. In this productive system, the microbial community is responsible for carrying out the nutrient dynamics between the components. The nutrimental transformations mainly consist in the transformation of chemical species from toxic compounds into available nutrients. In this particular field, the microbial research, the "Omic" technologies will allow a broader scope of studies about a current microbial profile inside aquaponics community, even in those species that currently are unculturable. This approach can also be useful to understand complex interactions of living components in the system. Until now, the analog studies were made to set up the microbial characterization on recirculation aquaculture systems (RAS). However, microbial community composition of aquaponics is still unknown. "Omic" technologies like metagenomic can help to reveal taxonomic diversity. The perspectives are also to begin the first attempts to sketch the functional diversity inside aquaponic systems and its ecological relationships. The knowledge of the emergent properties inside the microbial community, as well as the understanding of the biosynthesis pathways, can derive in future biotechnological applications. Thus, the aim of this review is to show potential applications of current "Omic" tools to characterize the microbial community in aquaponic systems.

Multidisciplinary oil spill modeling to protect coastal communities and the environment of the Eastern Mediterranean Sea.

PubMed

Alves, Tiago M; Kokinou, Eleni; Zodiatis, George; Radhakrishnan, Hari; Panagiotakis, Costas; Lardner, Robin

2016-11-10

We present new mathematical and geological models to assist civil protection authorities in the mitigation of potential oil spill accidents in the Eastern Mediterranean Sea. Oil spill simulations for 19 existing offshore wells were carried out based on novel and high resolution bathymetric, meteorological, oceanographic, and geomorphological data. The simulations show a trend for east and northeast movement of oil spills into the Levantine Basin, affecting the coastal areas of Israel, Lebanon and Syria. Oil slicks will reach the coast in 1 to 20 days, driven by the action of the winds, currents and waves. By applying a qualitative analysis, seabed morphology is for the first time related to the direction of the oil slick expansion, as it is able to alter the movement of sea currents. Specifically, the direction of the major axis of the oil spills, in most of the cases examined, is oriented according to the prevailing azimuth of bathymetric features. This work suggests that oil spills in the Eastern Mediterranean Sea should be mitigated in the very few hours after their onset, and before wind and currents disperse them. We explain that protocols should be prioritized between neighboring countries to mitigate any oil spills.

Applications of spectral methods to turbulent magnetofluids in space and fusion research

NASA Technical Reports Server (NTRS)

Montgomery, D.; Voigt, R. G. (Editor); Gottlieb, D. (Editor); Hussaini, M. Y. (Editor)

1984-01-01

Recent and potential applications of spectral method computation to incompressible, dissipative magnetohydrodynamics are surveyed. Linear stability problems for one dimensional, quasi-equilibria are approachable through a close analogue of the Orr-Sommerfeld equation. It is likely that for Reynolds-like numbers above certain as-yet-undetermined thresholds, all magnetofluids are turbulent. Four recent effects in MHD turbulence are remarked upon, as they have displayed themselves in spectral method computations: (1) inverse cascades; (2) small-scale intermittent dissipative structures; (3) selective decays of ideal global invariants relative to each other; and (4) anisotropy induced by a mean dc magnetic field. Two more conjectured applications are suggested. All the turbulent processes discussed are sometimes involved in current carrying confined fusion magnetoplasmas and in space plasmas.

Testing military grade magnetics (transformers, inductors and coils).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

Engineers and designers are constantly searching for test methods to qualify or 'prove-in' new designs. In the High Reliability world of military parts, design test, qualification tests, in process tests and product characteristic tests, become even more important. The use of in process and function tests has been adopted as a way of demonstrating that parts will operate correctly and survive its 'use' environments. This paper discusses various types of tests to qualify the magnetic components - the current carrying capability of coils, a next assembly 'as used' test, a corona test and inductance at temperature test. Each of thesemore » tests addresses a different potential failure on a component. The entire process from design to implementation is described.« less

Development and characterization of resveratrol nanoemulsions carrying dual-imaging agents

PubMed Central

Herneisey, Michele; Williams, Jonathan; Mirtic, Janja; Liu, Lu; Potdar, Sneha; Bagia, Christina; Cavanaugh, Jane E; Janjic, Jelena M

2016-01-01

Aim: Delivery of the natural anti-inflammatory compound resveratrol with nanoemulsions can dramatically improve its tissue targeting, bioavailability and efficacy. Current assessment of resveratrol delivery efficacy is limited to indirect pharmacological measures. Molecular imaging solves this problem. Results/methodology: Nanoemulsions containing two complementary imaging agents, near-infrared dye and perfluoropolyether (PFPE), were developed and evaluated. Nanoemulsion effects on macrophage uptake, toxicity and NO production were also evaluated. The presence of PFPE did not affect nanoemulsion size, zeta potential, colloidal stability, drug loading or drug release. Conclusion: PFPE nanoemulsions can be used in future studies to evaluate nanoemulsion biodistribution without interfering with resveratrol delivery and pharmacological outcomes. Developed nanoemulsions show promise as a versatile treatment strategy for cancer and other inflammatory diseases. Graphical abstract PMID:27834615

The role of lasers in dentistry: present and future.

PubMed

Pearson, G J; Schuckert, K H

2003-03-01

Lasers have been used for hard tissue cutting in dentistry for a number of years. The quality of the cavity preparation and the surface finish achievable is variable and is dependent on operating wavelength. The collateral damage, which may be produced at differing wavelengths, is quite marked. Lasers in current form are now able to remove tissue in bulk at a similar rate to conventional methods such as bur and turbine handpiece. Some lasers may, however, provide precision cutting, which may be developed further in the future. Alternative uses of laser light are potentially more beneficial in the shorter term. The use of diode lasers as a means of activating a photosensitizer to carry out photo-activated disinfection appears to be beneficial.

Waste minimisation in a hard chromiun plating Small Medium Enterprise (SME).

PubMed

Viguri, J R; Andrés, A; Irabien, A

2002-01-01

The high potential of waste stream minimisation in the metal finishing sector justifies specific studies of Small and Medium Enterprises (SME). In this work, the minimisation options of the wastes generated in a hard chromium plating activity have been analysed. The study has been performed in a small job shop company, which works in batch mode with big pieces. A process flowsheet after connecting the unit operations and determining the process inputs (raw and secondary materials) and outputs (waste streams) has been carried out. The main properties, quantity and current management of the waste streams have been shown. The obvious lack of information has been identified and finally the waste minimisation options that could be adopted by the company have been recorded.

The acceptance of virtual reality devices for cognitive rehabilitation: a report of positive results with schizophrenia.

PubMed

da Costa, Rosa Maria Esteves Moreira; de Carvalho, Luís Alfredo Vidal

2004-03-01

This study presents a process of virtual environment development supported by a cognitive model that is specific to cognitive deficits of diverse disorders or traumatic brain injury, and evaluates the acceptance of computer devices by a group of schizophrenic patients. The subjects that participated in this experiment accepted to work with computers and immersive glasses and demonstrated a high level of interest in the proposed tasks. No problems of illness have been observed. This experiment indicated that further research projects must be carried out to verify the value of virtual reality technology for cognitive rehabilitation of psychiatric patients. The results of the current study represent a small but necessary step in the realization of that potential.

Rydberg gas theory of a glow discharge plasma: I. Application to the electrical behaviour of a fast flowing glow discharge plasma.

PubMed

Mason, Rod S; Mitchell, David J; Dickinson, Paul M

2010-04-21

Current-voltage (I-V) curves have been measured, independent of the main discharge, for electricity passing through the steady state fast flowing 'afterglow' plasma of a low power dc glow discharge in Ar. Voltage profiles along the axial line of conduction have been mapped using fixed probes and potentiometry, and the mass spectra of cations emerging from the downstream sampling Cone, also acting as a probe anode, were recorded simultaneously. Floating double probe experiments were also carried out. The electrical behavior is consistent with the well established I-V characteristics of such discharges, but does not comply with classical plasma theory predictions. The plasma decays along the line of conduction, with a lifetime of approximately 1 ms, despite carrying a steady state current, and its potential is below that of the large surface area anode voltage; a situation which cannot exist in the presence of a conventional free ion-electron plasma, unless the electron temperature is super cold. Currents, large by comparison with the main discharge current, and independent of it, are induced to flow through the downstream plasma, from the Anode (acting as a cathode) to the anodic ion exit Cone, induced by electron impact ionisation at the anode, but without necessarily increasing the plasma density. It appears to be conducted by direct charge transfer between a part of the anode surface (acting as cathode to the auxiliary circuit) and the plasma, without secondary electron emission or heating, which suggests the direct involvement of Rydberg atom intermediates. The reaction energy defect (= the work function of the electrode surface) fits with the plasma potential threshold observed for the cathodic reaction to occur. A true free ion-electron plasma is readily detected by the observation of cations at the anode surface, when induced at the downstream anode, at high bias voltages, by the electron impact ionisation in the boundary region. In contrast to the classical model, the complex electrical (and mass spectrometric) behaviour fits qualitatively, but can be understood well, with the Rydberg gas model described in papers II and III (R. S. Mason, and R. S. Mason and P. Douglas, PCCP, 2010, DOI: 10.1039/b918081h and b918083d) over a wide range of probe bias voltages. The full cycle of behavior is then described for the development of a true secondary discharge within the downstream plasma.

30 CFR 7.402 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... wires not insulated from one another, suitable for carrying an electric current. Electric Cable. An assembly of one or more insulated conductors of electric current under a common or integral jacket. A cable... the primary electric current or power is transmitted. Signaling Cable. A fiber optic cable, or a cable...

30 CFR 7.402 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... wires not insulated from one another, suitable for carrying an electric current. Electric Cable. An assembly of one or more insulated conductors of electric current under a common or integral jacket. A cable... the primary electric current or power is transmitted. Signaling Cable. A fiber optic cable, or a cable...

30 CFR 7.402 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... wires not insulated from one another, suitable for carrying an electric current. Electric Cable. An assembly of one or more insulated conductors of electric current under a common or integral jacket. A cable... the primary electric current or power is transmitted. Signaling Cable. A fiber optic cable, or a cable...

Nanocomposites for neurodegenerative diseases: hydrogel-nanoparticle combinations for a challenging drug delivery.

PubMed

Giordano, Carmen; Albani, Diego; Gloria, Antonio; Tunesi, Marta; Rodilossi, Serena; Russo, Teresa; Forloni, Gianluigi; Ambrosio, Luigi; Cigada, Alberto

2011-12-01

Neurodegenerative disorders are expected to strike social and health care systems of developed countries heavily in the coming decades. Alzheimer's and Parkinson's diseases (AD/PD) are the most prevalent neurodegenerative pathologies, and currently their available therapy is only symptomatic. However, innovative potential drugs are actively under development, though their efficacy is sometimes limited by poor brain bioavailability and/or sustained peripheral degradation. To partly overcome these constraints, the development of drug delivery devices made by biocompatible and easily administrable materials might be a great adjuvant. In particular, materials science can provide a powerful tool to design hydrogels and nanoparticles as basic components of more complex nanocomposites that might ameliorate drug or cell delivery in AD/PD. This kind of approach is particularly promising for intranasal delivery, which might increase brain targeting of neuroprotective molecules or proteins. Here we review these issues, with a focus on nanoparticles as nanocomponents able to carry and tune drug release in the central nervous system, without ignoring warnings concerning their potential toxicity.

Effects of Plants and Isolates of Celastraceae Family on Cancer Pathways.

PubMed

Bukhari, Syed Nasir Abbas; Jantan, Ibrahim; Seyed, Mohamed Ali

2015-01-01

The evaluation of crude drugs of natural origin as sources of new effective anticancer agents continues to be important due to the lack of effective anticancer drugs currently used in practice which are generally accompanied with adverse effects at different levels of severity. The aim of this concise review is to gather existing literature on anticancer potential of extracts and compounds isolated from Celastraceae species. This review covers six genera (Maytenus, Tripterygium, Hippocratea, Gymnosporia, Celastrus and Austroplenckia) belonging to this family and their 33 isolates. Studies carried out by using different cell lines have shown remarkable indication of anticancer activity, however, only a restricted number of studies have been reported using in vivo tumor models. Some of the compounds, such as triptolide, celastrol and demethylzeylasteral from T. wilfordii, have been extensively studied on their mechanisms of action due to their potent activity on various cancer cell lines. Such promising lead compounds should generate considerable interest among scientists to improve their therapeutic potential with fewer side effects by molecular modification.

A G542X cystic fibrosis mouse model for examining nonsense mutation directed therapies.

PubMed

McHugh, Daniel R; Steele, Miarasa S; Valerio, Dana M; Miron, Alexander; Mann, Rachel J; LePage, David F; Conlon, Ronald A; Cotton, Calvin U; Drumm, Mitchell L; Hodges, Craig A

2018-01-01

Nonsense mutations are present in 10% of patients with CF, produce a premature termination codon in CFTR mRNA causing early termination of translation, and lead to lack of CFTR function. There are no currently available animal models which contain a nonsense mutation in the endogenous Cftr locus that can be utilized to test nonsense mutation therapies. In this study, we create a CF mouse model carrying the G542X nonsense mutation in Cftr using CRISPR/Cas9 gene editing. The G542X mouse model has reduced Cftr mRNA levels, demonstrates absence of CFTR function, and displays characteristic manifestations of CF mice such as reduced growth and intestinal obstruction. Importantly, CFTR restoration is observed in G542X intestinal organoids treated with G418, an aminoglycoside with translational readthrough capabilities. The G542X mouse model provides an invaluable resource for the identification of potential therapies of CF nonsense mutations as well as the assessment of in vivo effectiveness of these potential therapies targeting nonsense mutations.

Control system for a wound-rotor motor

DOEpatents

Ellis, James N.

1983-01-01

A load switching circuit for switching two or more transformer taps under load carrying conditions includes first and second parallel connected bridge rectifier circuits which control the selective connection of a direct current load to taps of a transformer. The first bridge circuit is normally conducting so that the load is connected to a first tap through the first bridge circuit. To transfer the load to the second tap, a switch is operable to connect the second bridge circuit to a second tap, and when the second bridge circuit begins to conduct, the first bridge circuit ceases conduction because the potential at the second tap is higher than the potential at the first tap, and the load is thus connected to the second tap through the second bridge circuit. The load switching circuit is applicable in a motor speed controller for a wound-rotor motor for effecting tap switching as a function of motor speed while providing a stepless motor speed control characteristic.

AC power generation from microbial fuel cells

NASA Astrophysics Data System (ADS)

Lobo, Fernanda Leite; Wang, Heming; Forrestal, Casey; Ren, Zhiyong Jason

2015-11-01

Microbial fuel cells (MFCs) directly convert biodegradable substrates to electricity and carry good potential for energy-positive wastewater treatment. However, the low and direct current (DC) output from MFC is not usable for general electronics except small sensors, yet commercial DC-AC converters or inverters used in solar systems cannot be directly applied to MFCs. This study presents a new DC-AC converter system for MFCs that can generate alternating voltage in any desired frequency. Results show that AC power can be easily achieved in three different frequencies tested (1, 10, 60 Hz), and no energy storage layer such as capacitors was needed. The DC-AC converter efficiency was higher than 95% when powered by either individual MFCs or simple MFC stacks. Total harmonic distortion (THD) was used to investigate the quality of the energy, and it showed that the energy could be directly usable for linear electronic loads. This study shows that through electrical conversion MFCs can be potentially used in household electronics for decentralized off-grid communities.

Lexical stress encoding in single word production estimated by event-related brain potentials.

PubMed

Schiller, Niels O

2006-09-27

An event-related brain potentials (ERPs) experiment was carried out to investigate the time course of lexical stress encoding in language production. Native speakers of Dutch viewed a series of pictures corresponding to bisyllabic names which were either stressed on the first or on the second syllable and made go/no-go decisions on the lexical stress location of those picture names. Behavioral results replicated a pattern that was observed earlier, i.e. faster button-press latencies to initial as compared to final stress targets. The electrophysiological results indicated that participants could make a lexical stress decision significantly earlier when picture names had initial than when they had final stress. Moreover, the present data suggest the time course of lexical stress encoding during single word form formation in language production. When word length is corrected for, the temporal interval for lexical stress encoding specified by the current ERP results falls into the time window previously identified for phonological encoding in language production.

Genetics: Implications for Prevention and Management of Coronary Artery Disease.

PubMed

Assimes, Themistocles L; Roberts, Robert

2016-12-27

An exciting new era has dawned for the prevention and management of coronary artery disease (CAD) utilizing genetic risk variants. The recent identification of over 60 susceptibility loci for CAD confirms not only the importance of established risk factors, but also the existence of many novel causal pathways that are expected to improve our understanding of the genetic basis of CAD and facilitate the development of new therapeutic agents over time. Concurrently, Mendelian randomization studies have provided intriguing insights on the causal relationship between CAD-related traits, and highlight the potential benefits of long-term modifications of risk factors. Last, genetic risk scores of CAD may serve not only as prognostic, but also as predictive markers, and carry the potential to considerably improve the delivery of established prevention strategies. This review will summarize the evolution and discovery of genetic risk variants for CAD and their current and future clinical applications. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Spatial Data Uncertainty in a Webgis Tool Supporting Sediments Management in Wallonia

NASA Astrophysics Data System (ADS)

Stéphenne, N. R.; Beaumont, B.; Veschkens, M.; Palm, S.; Charlemagne, C.

2015-08-01

This paper describes a WebGIS prototype developed for the Walloon administration to improve the communication and the management of sediments dredging actions carried out in rivers and lakes. In Wallonia, levelling dredged sediments on banks requires an official authorization from the administration. This request refers to geospatial datasets such as the official land use map, the cadastral map or the distance to potential pollution sources. Centralising geodatabases within a web interface facilitate the management of these authorizations for the managers and the central administration. The proposed system integrates various data from disparate sources. Some issues in map scale, spatial search quality and cartographic visualisation are discussed in this paper with the solutions provided. The prototype web application is currently discussed with some potential users in order to understand in which way this tool facilitate the communication, the management and the quality of the authorisation process. The structure of the paper states the why, what, who and how of this communication tool with a special focus on errors and uncertainties.

Effect of slightly acid pH with or without chloride in radioactive water on the corrosion of maraging steel

NASA Astrophysics Data System (ADS)

Bellanger, G.; Rameau, J. J.

1996-02-01

This study was carried out to ascertain the behavior of maraging steel used in the tanks of French plants for reprocessing radioactive water which may contain chloride ions at pH 3. The rest or corrosion potentials can be either in the transpassive or active regions due to the presence of radiolytic species. The corrosion current and potential depend on the pH and intermediates formed on the surface in the active region; therefore, maraging steel behavior was studied by cyclic voltammetry without and with electrode rotation and different acid pH which provide an indication of mechanisms, modification of local pH and transient formation. In the passive -transpassive region, breakdown and porosity in the oxide appear with or without chloride, according to electrochemical impedance spectroscopy. In presence of chloride, the corrosion kinetics were obtained by cyclic voltammetry and electrochemical impedance spectroscopy. The anodic and cathodic areas of maraging steel corroded by pitting were shown using the Scanning Reference Electrode Technique.

Controlling hollow relativistic electron beam orbits with an inductive current divider

DOE PAGES

Swanekamp, S. B.; Richardson, A. S.; Angus, J. R.; ...

2015-02-06

A passive method for controlling the trajectory of an intense, hollow electron beam is proposed using a vacuum structure that inductively splits the beam's return current. A central post carries a portion of the return current (I 1), while the outer conductor carries the remainder (I 2). An envelope equation appropriate for a hollow electron beam is derived and applied to the current divider. The force on the beam trajectory is shown to be proportional to (I 2-I 1), while the average force on the envelope (the beam width) is proportional to the beam current I b = (I 2more » + I 1). The values of I 1 and I 2 depend on the inductances in the return-current path geometries. Proper choice of the return-current geometries determines these inductances and offers control over the beam trajectory. As a result, solutions using realistic beam parameters show that, for appropriate choices of the return-current-path geometry, the inductive current divider can produce a beam that is both pinched and straightened so that it approaches a target at near-normal incidence with a beam diameter that is on the order of a few mm.« less

Second-Generation High-Temperature Superconductor Wires for the Electric Power Grid

NASA Astrophysics Data System (ADS)

Malozemoff, A. P.

2012-08-01

Superconductors offer major advantages for the electric power grid, including high current and power capacity, high efficiency arising from the lossless current flow, and a unique current-limiting functionality arising from a superconductor-to-resistive transition. These advantages can be brought to bear on equipment such as underground power cables, fault current limiters, rotating machinery, transformers, and energy storage. The first round of significant commercial-scale superconductor power-equipment demonstrations, carried out during the past decade, relied on a first-generation high-temperature superconductor (HTS) wire. However, during the past few years, with the recent commercial availability of high-performance second-generation HTS wires, power-equipment demonstrations have increasingly been carried out with these new wires, which bring important advantages. The foundation is being laid for commercial expansion of this important technology into the power grid.

Threshold fluctuations in a superconducting current-carrying bridge

NASA Astrophysics Data System (ADS)

Marychev, P. M.; Vodolazov, D. Yu

2017-07-01

We calculate the energy of threshold fluctuation δ {F}{{thr}} which triggers the transition of a superconducting current-carrying bridge to the resistive state. We show that the dependence δ {F}{{thr}}{(I)\\propto {I}{{dep}}{\\hslash }(1-I/{I}{{dep}})}5/4/e, found by Langer and Ambegaokar for a long bridge with length L\\gg ξ , holds far below the critical temperature in both dirty and clean limits (here I dep is the depairing current of the bridge and ξ is a coherence length). We also find that even a ‘weak’ local defect (leading to a small suppression of the critical current of the bridge {I}{{c}}≲ {I}{{dep}}) provides δ {F}{{thr}}\\propto {I}{{c}}{\\hslash }{(1-I/{I}{{c}})}3/2/e, typical for a short bridge with L\\ll ξ or a Josephson junction.

Cytogenetic damage analysis in mice chronically exposed to low-dose internal tritium beta-particle radiation.

PubMed

Roch-Lefèvre, Sandrine; Grégoire, Eric; Martin-Bodiot, Cécile; Flegal, Matthew; Fréneau, Amélie; Blimkie, Melinda; Bannister, Laura; Wyatt, Heather; Barquinero, Joan-Francesc; Roy, Laurence; Benadjaoud, Mohamed; Priest, Nick; Jourdain, Jean-René; Klokov, Dmitry

2018-06-08

The aim of this study was to carry out a comprehensive examination of potential genotoxic effects of low doses of tritium delivered chronically to mice and to compare these effects to the ones resulting from equivalent doses of gamma-irradiation. Mice were chronically exposed for one or eight months to either tritiated water (HTO) or organically bound tritium (OBT) in drinking water at concentrations of 10 kBq/L, 1 MBq/L or 20 MBq/L. Dose rates of internal β-particle resulting from such tritium treatments were calculated and matching external gamma-exposures were carried out. We measured cytogenetic damage in bone marrow and in peripheral blood lymphocytes (PBLs) and the cumulative tritium doses (0.009 - 181 mGy) were used to evaluate the dose-response of OBT in PBLs, as well as its relative biological effectiveness (RBE). Neither tritium, nor gamma exposures produced genotoxic effects in bone marrow. However, significant increases in chromosome damage rates in PBLs were found as a result of chronic OBT exposures at 1 and 20 M Bq/L, but not at 10 kBq/L. When compared to an external acute gamma-exposure ex vivo , the RBE of OBT for chromosome aberrations induction was evaluated to be significantly higher than 1 at cumulative tritium doses below 10 mGy. Although found non-existent at 10 kBq/L (the WHO limit), the genotoxic potential of low doses of tritium (>10 kBq/L), mainly OBT, may be higher than currently assumed.

Phosphotyrosine profiling identifies ephrin receptor A2 as a potential therapeutic target in esophageal squamous‐cell carcinoma

PubMed Central

Syed, Nazia; Barbhuiya, Mustafa A.; Pinto, Sneha M.; Nirujogi, Raja Sekhar; Renuse, Santosh; Datta, Keshava K.; Khan, Aafaque Ahmad; Srikumar, Kotteazeth; Prasad, T. S. Keshava; Kumar, M. Vijaya; Kumar, Rekha Vijay; Chatterjee, Aditi; Pandey, Akhilesh

2015-01-01

Esophageal squamous‐cell carcinoma (ESCC) is one of the most common malignancies in Asia. Currently, surgical resection of early‐stage tumor is the best available treatment. However, most patients present late when surgery is not an option. Data suggest that chemotherapy regimens are inadequate for clinical management of advanced cancer. Targeted therapy has emerged as one of the most promising approaches to treat several malignancies. A prerequisite for developing targeted therapy is prior knowledge of proteins and pathways that drive proliferation in malignancies. We carried out phosphotyrosine profiling across four different ESCC cell lines and compared it to non‐neoplastic Het‐1A cell line to identify activated tyrosine kinase signaling pathways in ESCC. A total of 278 unique phosphopeptides were identified across these cell lines. This included several tyrosine kinases and their substrates that were hyperphosphorylated in ESCC. Ephrin receptor A2 (EPHA2), a receptor tyrosine kinase, was hyperphosphorylated in all the ESCC cell lines used in the study. EPHA2 is reported to be oncogenic in several cancers and is also known to promote metastasis. Immunohistochemistry‐based studies have revealed EPHA2 is overexpressed in nearly 50% of ESCC. We demonstrated EPHA2 as a potential therapeutic target in ESCC by carrying out siRNA‐based knockdown studies. Knockdown of EPHA2 in ESCC cell line TE8 resulted in significant decrease in cell proliferation and invasion, suggesting it is a promising therapeutic target in ESCC that warrants further evaluation. PMID:25366905

The effect of conventional wastewater treatment on the levels of antimicrobial-resistant bacteria in effluent: a meta-analysis of current studies.

PubMed

Harris, Suvi; Cormican, Martin; Cummins, Enda

2012-12-01

Antimicrobial agents in the environment are a cause for concern. Antimicrobial drug residues and their metabolites reach the aquatic and terrestrial environment primarily through wastewater treatment plants (WWTP). In addition to the potential direct negative health and environmental effects, there is potential for the development of antimicrobial-resistant bacteria. Residue levels below the minimum inhibitory concentration for a bacterial species can be important in selection of resistance. There is uncertainty associated with resistance formation during WWTP processing. A meta-analysis study was carried out to analyse the effect of WWTP processing on the levels of antimicrobial-resistant bacteria within bacterial populations. An analysis of publications relating to multiple antimicrobial-resistant (MAR) bacteria (n = 61), single antimicrobial-resistant (SAR) E. coli (n = 81) and quinolone/fluoroquinolone-resistant (FR) bacteria (n = 19) was carried out. The odds-ratio (OR) of MAR (OR = 1.60, p < 0.01), SAR (OR = 1.33, p < 0.01) and FR (OR = 1.19, p < 0.01) bacteria was determined. The results infer that WWTP processing results in an increase in the proportion of resistant bacteria in effluent, even though the overall bacterial population may have reduced (i.e. a reduction in total bacterial numbers but an increase in the percentage of resistant bacteria). The results support the need for further research into the development of antimicrobial-resistant strains and possible selective pressures operating in WWTPs.

Deformation of the free surface of a conducting fluid in the magnetic field of current-carrying linear conductors

NASA Astrophysics Data System (ADS)

Zubarev, N. M.; Zubareva, O. V.

2017-06-01

The magnetic shaping problem is studied for the situation where a cylindrical column of a perfectly conducting fluid is deformed by the magnetic field of a system of linear current-carrying conductors. Equilibrium is achieved due to the balance of capillary and magnetic pressures. Two two-parametric families of exact solutions of the problem are obtained with the help of conformal mapping technique. In accordance with them, the column essentially deforms in the cross section up to its disintegration.

Investigating the potential for ethnic group harm in collaborative genomics research in Africa: Is ethnic stigmatisation likely?

PubMed Central

de Vries, Jantina; Jallow, Muminatou; Williams, Thomas N.; Kwiatkowski, Dominic; Parker, Michael; Fitzpatrick, Raymond

2013-01-01

A common assumption in genomics research is that the use of ethnic categories has the potential to lead to ethnic stigmatisation – particularly when the research is done on minority populations. Yet few empirical studies have sought to investigate the relation between genomics and stigma, and fewer still with a focus on Africa. In this paper, we investigate the potential for genomics research to lead to harms to ethnic groups. We carried out 49 semi-structured, open-ended interviews with stakeholders in a current medical genomics research project in Africa, MalariaGEN. Interviews were conducted with MalariaGEN researchers, fieldworkers, members of three ethics committees who reviewed MalariaGEN project proposals, and with members of the two funding bodies providing support to the MalariaGEN project. Interviews were conducted in Kenya, The Gambia and the UK between June 2008 and October 2009. They covered a range of aspects relating to the use of ethnicity in the genomics project, including views on adverse effects of the inclusion of ethnicity in such research. Drawing on the empirical data, we argue that the risk of harm to ethnic groups is likely to be more acute in specific types of genomics research. We develop a typology of research questions and projects that carry a greater risk of harm to the populations included in genomics research. We conclude that the potential of generating harm to ethnic groups in genomics research is present if research includes populations that are already stigmatised or discriminated against, or where the research investigates questions with particular normative implications. We identify a clear need for genomics researchers to take account of the social context of the work they are proposing to do, including understanding the local realities and relations between ethnic groups, and whether diseases are already stigmatised. PMID:22749442