Science.gov

Sample records for fast rise time

  1. Rugged calorimeter with a fast rise time

    SciTech Connect

    McMurtry, W.M.; Dolce, S.R.

    1980-01-01

    An intrinsic 1-mil-thick gold foil calorimeter has been developed which rises to 95% of the energy deposited in less than 2 microseconds. This calorimeter is very rugged, and can withstand rough handling without damage. The time constant is long, in the millisecond range, because of its unique construction. Use of this calorimeter has produced 100% data recovery, and agreement with true deposition to less than 10%.

  2. Fast rise times and the physical mechanism of deep earthquakes

    NASA Technical Reports Server (NTRS)

    Houston, H.; Williams, Q.

    1991-01-01

    A systematic global survey of the rise times and stress drops of deep and intermediate earthquakes is reported. When the rise times are scaled to the seismic moment release of the events, their average is nearly twice as fast for events deeper than about 450 km as for shallower events.

  3. Fast rise time IR detectors for lepton colliders

    NASA Astrophysics Data System (ADS)

    Drago, A.; Bini, S.; Cestelli Guidi, M.; Marcelli, A.; Pace, E.

    2016-07-01

    Diagnostics is a fundamental issue for accelerators whose demands are continuously increasing. In particular bunch-by-bunch diagnostics is a key challenge for the latest generation of lepton colliders and storage rings. The Frascati Φ-factory, DAΦNE, colliding at 1.02 GeV in the centre of mass, hosts in the main rings few synchrotron radiation beamlines and two of them collect the synchrotron radiation infrared emission: SINBAD from the electron ring and 3+L from the positron ring. At DAΦNE each bucket is 2.7 ns long and particles are gathered in bunches emitting pulsed IR radiation, whose intensity in the long wavelength regime is directly proportional to the accumulated particles. Compact uncooled photoconductive HgCdTe detectors have been tested in both beamlines using dedicated optical layouts. Actually, the fast rise time of HgCdTe semiconductors give us the chance to test bunch-by-bunch devices for both longitudinal and transverse diagnostics. For the longitudinal case, single pixel detectors have been used, while for the transverse diagnostics, multi-pixel array detectors, with special custom design, are under test. This contribution will briefly describe the status of the research on fast IR detectors at DAΦNE, the results obtained and possible foreseen developments.

  4. Accurate measurement of the rise and decay times of fast scintillators with solid state photon counters

    NASA Astrophysics Data System (ADS)

    Seifert, S.; Steenbergen, J. H. L.; van Dam, H. T.; Schaart, D. R.

    2012-09-01

    In this work we present a measurement setup for the determination of scintillation pulse shapes of fast scintillators. It is based on a time-correlated single photon counting approach that utilizes the correlation between 511 keV annihilation photons to produce start and stop signals in two separate crystals. The measurement is potentially cost-effective and simple to set up while maintaining an excellent system timing resolution of 125 ps. As a proof-of-concept the scintillation photon arrival time histograms were recorded for two well-known, fast scintillators: LYSO:Ce and LaBr3:5%Ce. The scintillation pulse shapes were modeled as a linear combination of exponentially distributed charge transfer and photon emission processes. Correcting for the system timing resolution, the exponential time constants were extracted from the recorded histograms. A decay time of 43 ns and a rise time of 72 ps were determined for LYSO:Ce thus demonstrating the capability of the system to accurately measure very fast rise times. In the case of LaBr3:5%Ce two processes were observed to contribute to the rising edge of the scintillation pulse. The faster component (270 ps) contributes with 72% to the rising edge of the scintillation pulse while the second, slower component (2.0 ns) contributes with 27%. The decay of the LaBr3:5%Ce scintillation pulse was measured to be 15.4 ns with a small contribution (2%) of a component with a larger time constant (130 ns).

  5. CHARACTERISTICS OF A FAST RISE TIME POWER SUPPLY FOR A PULSED PLASMA REACTOR FOR CHEMICAL VAPOR DESTRUCTION

    EPA Science Inventory

    Rotating spark gap devices for switching high-voltage direct current (dc) into a corona plasma reactor can achieve pulse rise times in the range of tens of nanoseconds. The fast rise times lead to vigorous plasma generation without sparking at instantaneous applied voltages highe...

  6. Application of piezoelectric stress gauges to the measurement of fast-rise-time multimegampere electric currents

    SciTech Connect

    Hanson, D.L.; Spielman, R.B.; Seamen, J.F.; Struve, K.W.

    1993-07-01

    Modeling of load behavior in Z-pinch plasma radiation sources driven by high current generators requires accurate measurement of fast-rise-time multimegampere electrical currents close to the load. Using a novel application of high pressure technology, we have demonstrated that fast-response piezoelectric stress transducers can measure such currents under conditions of extremely high current density, induced electric fields, and bremsstrahlung radiation where conventional current diagnostics fail. Large signal, nanosecond-time-resolution lithium niobate piezoelectric stress gauges are employed to directly measure the magnetic pressure B{sup 2}/2{mu}{sub 0} = {mu}{sub 0}I{sup 2}/8{pi}{sup 2}r{sup 2} generated at radius r by a current I flowing in a radial transmission line near the load of a pulsed power current source. With a current diagnostic consisting of a pure tungsten electrode on a Y-cut lithium niobate stress gauge, current densities up to 1/2{pi}cr = 78MA/m can be measured before the electrode yield strength and piezoelectric operating stress limit are exceeded. Based on this work, we have developed a compact modular current probe for use on the high current (20--25 MA) DECADE simulator being constructed for the Defense Nuclear Agency. We also describe recent work extending this measurement technique to higher current densities (125 MA/m) using a cooper-sapphire electrode impedance stack on an X-cut quartz piezoelectric element.

  7. Application of piezoelectric stress gauges to the measurement of fast-rise-time multimegampere electric currents

    NASA Astrophysics Data System (ADS)

    Hanson, D. L.; Spielman, R. B.; Seamen, J. F.; Struve, K. W.

    1993-02-01

    Modeling of load behavior in Z-pinch plasma radiation sources driven by high current generators requires accurate measurement of fast-rise-time multimegampere electrical currents close to the load. Using a novel application of high pressure technology, we have demonstrated that fast-response piezoelectric stress transducers can measure such currents under conditions of extremely high current density, induced electric fields, and bremsstrahlung radiation where conventional current diagnostics fail. Large signal, nanosecond-time-resolution lithium niobate piezoelectric stress gauges are employed to directly measure the magnetic pressure B(sup 2)/2(mu)(sub 0) = (mu)(sub 0)I(sup 2)/8(pi)(sup 2)r(sup 2) generated at radius r by a current I flowing in a radial transmission line near the load of a pulsed power current source. With a current diagnostic consisting of a pure tungsten electrode on a Y-cut lithium niobate stress gauge, current densities up to 1/2(pi)cr = 78MA/m can be measured before the electrode yield strength and piezoelectric operating stress limit are exceeded. Based on this work, we have developed a compact modular current probe for use on the high current (20-25 MA) DECADE simulator being constructed for the Defense Nuclear Agency. We also describe recent work extending this measurement technique to higher current densities (125 MA/m) using a copper-sapphire electrode impedance stack on an X-cut quartz piezoelectric element.

  8. Application of piezoelectric stress gauges to the measurement of fast-rise-time multimegampere electric currents

    NASA Astrophysics Data System (ADS)

    Hanson, D. L.; Struve, K. W.; Spielman, R. B.; Seamen, J. F.

    1994-07-01

    Modeling of load behavior in Z-pinch plasma radiation sources driven by high current generators requires accurate measurement of fast-rise-time multimegampere electrical currents close to the load. Using a novel applications of high pressure technology, we have demonstrated that fast-response piezoelectric stress transducers can measure such currents under conditions of extremely high current density, induced electric fields, and bremsstrahlung radiation where conventional current diagnostics fail. Large signal, nanosecond-time-resolution lithium niobate piezoelectric stress gauges are employed to directly measure the magnetic pressure B2/dμ0=μ0I2/ 8π2r2 generated at radius r by a curret I flowing in a radial transmission line near the load of a pulsed power current source. With a current diagnostic consisting of a pure tungsten electrode of a Y-cut lithium niobate stress gauge, current densities up to I/2πr=78 MA/m can be measured before the electrode yield strength and piezoelectric operating stress limit are exceeded. Based on this work, we have developed a compact modular current probe for use on the high current (20-25 MA) DECADE simulator being constructed for the Defense Nuclear Agency. We also describe recent work extending this measurement technique to higher current densities (125 MA/m) using a copper-sapphire electrode impedance stack on an X-cut quartz piezoelectric element.

  9. High-Voltage Power Supply With Fast Rise and Fall Times

    NASA Technical Reports Server (NTRS)

    Bearden, Douglas B.; Acker, Richard M.; Kapuslka, Robert E.

    2007-01-01

    A special-purpose high-voltage power supply can be electronically switched on and off with fast rise and fall times, respectively. The output potential is programmable from 20 to 1,250 V. An output current of 50 A can be sustained at 1,250 V. The power supply was designed specifically for electronically shuttering a microchannel plate in an x-ray detector that must operate with exposure times as short as 1 ms. The basic design of the power supply is also adaptable to other applications in which there are requirements for rapid slewing of high voltages. The power-supply circuitry (see figure) includes a preregulator, which is used to program the output at 1/30 of the desired output potential. After the desired voltage has been set, the outputs of a pulse width modulator (PWM) are enabled and used to amplify the preregulator output potential by 30. The amplification is achieved by use of two voltage doublers with a transformer that has two primary and two secondary windings. A resistor is used to limit the current by controlling the drive voltage of two field-effect transistors (FETs) during turn-on of the PWM. A pulse transformer is used to turn on four FETs to short-circuit four output capacitors when the outputs of the PWM have been disabled. The most notable aspects of the performance of the power supply are a rise time of only 80 s and a fall time of only 60 s at a load current of 50 A or less. Another notable aspect is that the application of a 0-to-5-V square wave to a shutdown pin of the PWM causes the production of a 0-to-1,250-V square wave at the output terminals.

  10. A 200 kV fast rise time, low jitter, trigger system with magnetic pulse sharpener

    SciTech Connect

    Jaitly, N.C.; Coleman, M.D.; Ramrus, A.; Earley, L.M.; Downing, J.N.; Reisch, H.H.; Caudill, L.D.; Eversol, S.A.

    1992-09-01

    The DARHT Facility is being designed at Los Alamos national Laboratory to produce high resolution flash radiographs of hydrodynamic experiments. Two linear induction accelerators (LIA), each in the range of 16 to 20 MeV, will be used to produce intense bremsstrahlung X-ray pulses of short duration (60 ns flat top). Each LIA will produce a 3 kA, high brightness, electron beam using a 4 MeV injector and a series of 250 kV induction cells. Technology demonstration of key accelerator subsystems is under progress at the DARHT Integrated Test Stand (ITS). The eight inductions cells present in the ITS are driven by a Maxwell prototype Induction Cell Pulsed Power supply (ICPPS) which provides 250 kV, 70 ns pulses via four Blumieins. Each Blumiein drives two cells and is triggered using independently controlled trigger units. This turnkey DARHT Trigger System, consisting of four separate trigger units, provides 200 kV trigger pulses with low jitter and fast rise time to each of the four Blumiein coaxial spark gaps. Details of the trigger system design and results obtained during extensive testing at Maxwell are described.

  11. Considerations for human exposure standards for fast-rise-time high-peak-power electromagnetic pulses.

    PubMed

    Merritt, J H; Kiel, J L; Hurt, W D

    1995-06-01

    Development of new emitter systems capable of producing high-peak-power electromagnetic pulses with very fast rise times and narrow pulse widths is continuing. Such directed energy weapons systems will be used in the future to defeat electronically vulnerable targets. Human exposures to these pulses can be expected during testing and operations. Development of these technologies for radar and communications purposes has the potential for wider environmental exposure, as well. Current IEEE C95.1-1991 human exposure guidelines do not specifically address these types of pulses, though limits are stated for pulsed emissions. The process for developing standards includes an evaluation of the relevant bioeffects data base. A recommendation has been made that human exposure to ultrashort electromagnetic pulses that engender electromagnetic transients, called precursor waves, should be avoided. Studies that purport to show the potential for tissue damage induced by such pulses were described. The studies cited in support of the recommendation were not relevant to the issues of tissue damage by propagated pulses. A number of investigations are cited in this review that directly address the biological effects of electromagnetic pulses. These studies have not shown evidence of tissue damage as a result of exposure to high-peak-power pulsed microwaves. It is our opinion that the current guidelines are sufficiently protective for human exposure to these pulses. PMID:7646411

  12. A 200 kV fast rise time, low jitter, trigger system with magnetic pulse sharpener

    SciTech Connect

    Jaitly, N.C.; Ramrus, A.; Coleman, M.D.; Earley, L.M.; Downing, J.N.; Reisch, H.H.; Caudill, L.D.; Eversol, S.A.

    1993-12-31

    The DARHT Facility is being designed at Los Alamos National Laboratory to produce high resolution flash radiographs of hydrodynamic experiments. Two linear induction accelerators (LIA), each in the range of 16 to 20 MeV, will be used to produce intense bremsstrahlung X-ray pulses of short duration (60 ns flat top). Each LIA will produce a 3 kA, high brightness, electron beam using a 4 MeV injector and a series of 250 kV induction cells. Technology demonstration of key accelerator subsystems is under progress at the DARHT Integrated Test Stand (ITS). The eight inductions cells present in the ITS are driven by a Maxwell prototype Induction Cell Pulsed Power Supply (ICPPS) which provides 250 kV, 70ns pulses via four Blumleins. Each Blumlein drives two cells and is triggered using independently controlled trigger units. This turnkey DARHT Trigger System, consisting of four separate trigger units, provides 200 kV trigger pulses with low jitter and fast rise time to each of the four Blumlein coaxial spark gaps. Details of the trigger system design and results obtained during extensive testing at Maxwell are described.

  13. Destruction of hazardous air pollutants using a fast rise time pulsed corona reactor

    SciTech Connect

    Korzekwa, R.A.; Grothaus, M.G.; Hutcherson, R.K.; Roush, R.A.; Brown, R.

    1998-04-01

    Increasingly stringent environmental regulation imposed on both the military and civilian sectors has created a growing demand for alternative abatement methods for a variety of hazardous compounds. One alternative, the nonthermal plasma, shows promise of providing an efficient means for the destruction of dilute concentrations of hazardous air pollutants. The Dahlgren Laboratory of the Naval Surface Warfare Center has extensively investigated one type of nonthermal plasma discharge, the pulsed corona reactor, for the destruction of volatile organic compounds and chemical warfare agents. In this reactor, a fast rise time ({approximately}10ns), short duration ({lt}100ns), high-voltage pulse is repetitively delivered to a wire-cylinder electrode geometry, thereby producing a multitude of streamer discharges along its length. The resulting nonthermal plasma contains highly reactive chemical radicals which can interact with and destroy the hazardous molecules entrained in the ambient atmosphere flowing through the reactor volume. Increased electrical efficiency was obtained using a combination of high efficiency constant-current capacitor-charging, high repetition-rate spark gap switching, and resonant energy transfer to the reactor. Promising results have been obtained for toluene, methylene chloride, and dichlorodifluoromethane in air at concentrations of a few hundred parts per million. The device has been operated at voltages up to 30 kV, pulse repetition rates up to 1.4 kHz, and flow rates up to 60 scr(l)/min. Detailed electrical measurements have been made to properly characterize the electrical properties of the pulsed corona reactor and to validate subsequent improvements in the reactor energy efficiency. {copyright} {ital 1998 American Institute of Physics.}

  14. Fast Rise Time and High Voltage Nanosecond Pulses at High Pulse Repetition Frequency

    NASA Astrophysics Data System (ADS)

    Miller, Kenneth E.; Ziemba, Timothy; Prager, James; Picard, Julian; Hashim, Akel

    2015-09-01

    Eagle Harbor Technologies (EHT), Inc. is conducting research to decrease the rise time and increase the output voltage of the EHT Nanosecond Pulser product line, which allows for independently, user-adjustable output voltage (0 - 20 kV), pulse width (20 - 500 ns), and pulse repetition frequency (0 - 100 kHz). The goals are to develop higher voltage pulses (50 - 60 kV), decrease the rise time from 20 to below 10 ns, and maintain the high pulse repetition capabilities. These new capabilities have applications to pseudospark generation, corona production, liquid discharges, and nonlinear transmission line driving for microwave production. This work is supported in part by the US Navy SBIR program.

  15. From RISING to the DESPEC fast-timing project within NUSTAR at FAIR: sub-nanosecond nuclear timing spectroscopy with LaBr3 scintillators.

    PubMed

    Regan, P H

    2012-07-01

    This paper summarises a presentation given at the IRRMA8 conference in June 2011 which reviewed briefly the topic of current research studies in the evolution of nuclear structure with changing proton and neutron numbers. A short review of relevant contemporary spectroscopic studies of the structure of nuclei with highly exotic N/Z ratios using projectile fragmentation and fission reactions is given, together with an overview of some of the physics research aims to be attacked using the proposed Decay Spectroscopy (DESPEC) LaBr3 Fast-Timing gamma-ray array for the NUSTAR project at the upcoming Facility for Anti-Proton and Ion Research (FAIR). Examples of recent results using both 'isomer' and β--delayed gamma-ray decay measurements with the Stopped RISING hyper-pure germanium array at GSI are summarised and used to highlight some of the fundamental physics studies which are expected to become available in this area of research in the coming decade. Examples of the performance of cerium-doped LaBr3 detectors from 'in-beam' test experiments are presented together with initial plans for the geometry of the planned multi-detector LaBr3(Ce) array for DESPEC. PMID:22285659

  16. Amplitude- and rise-time-compensated filters

    DOEpatents

    Nowlin, Charles H.

    1984-01-01

    An amplitude-compensated rise-time-compensated filter for a pulse time-of-occurrence (TOOC) measurement system is disclosed. The filter converts an input pulse, having the characteristics of random amplitudes and random, non-zero rise times, to a bipolar output pulse wherein the output pulse has a zero-crossing time that is independent of the rise time and amplitude of the input pulse. The filter differentiates the input pulse, along the linear leading edge of the input pulse, and subtracts therefrom a pulse fractionally proportional to the input pulse. The filter of the present invention can use discrete circuit components and avoids the use of delay lines.

  17. Slow-rise and Fast-rise Phases of an Erupting Solar Filament and Flare Emission Onset

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Moore, Ronald L.

    2005-01-01

    We observe the eruption of an active-region solar filament of 1998 July 11 using high time cadence and high spatial resolution EUV observations from the TRACE satellite, along with soft X-ray images from the soft X-ray telescope (SXT) on the Yohkoh satellite, hard X-ray fluxes from the BATSE instrument on the Compton Gamma Ray Observatory (CGRO) satellite and from the hard X-ray telescope (HXT) on Yohkoh, and ground-based magnetograms. We concentrate on the initiation of the eruption in an effort to understand the eruption mechanism. Prior to eruption the filament undergoes slow upward movement in a "slow rise" phase with an approximately constant velocity of about 15 km/s that lasts about 10 min. It then erupts in a "fast-rise" phase, accelerating to a velocity of about 200 km/s in about 5 min, and then decelerating to approximately 150 km/s over the next 5 min. EUV brightenings begin about concurrent with the start of the filament's slow rise, and remain immediately beneath the rising filament during the slow rise; initial soft X-ray brightenings occur at about the same time and location. Strong hard X-ray emission begins after the onset of the fast rise, and does not peak until the filament has traveled to a substantial altitude (to a height about equal to the initial length of the erupting filament) beyond its initial location. Additional information is available in the original extended abstract.

  18. Rise Time Measurement for Ultrafast X-Ray Pulses

    DOEpatents

    Celliers, Peter M.; Weber, Franz A.; Moon, Stephen J.

    2005-04-05

    A pump-probe scheme measures the rise time of ultrafast x-ray pulses. Conventional high speed x-ray diagnostics (x-ray streak cameras, PIN diodes, diamond PCD devices) do not provide sufficient time resolution to resolve rise times of x-ray pulses on the order of 50 fs or less as they are being produced by modern fast x-ray sources. Here, we are describing a pump-probe technique that can be employed to measure events where detector resolution is insufficient to resolve the event. The scheme utilizes a diamond plate as an x-ray transducer and a p-polarized probe beam.

  19. Rise time measurement for ultrafast X-ray pulses

    DOEpatents

    Celliers, Peter M.; Weber, Franz A.; Moon, Stephen J.

    2005-04-05

    A pump-probe scheme measures the rise time of ultrafast x-ray pulses. Conventional high speed x-ray diagnostics (x-ray streak cameras, PIN diodes, diamond PCD devices) do not provide sufficient time resolution to resolve rise times of x-ray pulses on the order of 50 fs or less as they are being produced by modern fast x-ray sources. Here, we are describing a pump-probe technique that can be employed to measure events where detector resolution is insufficient to resolve the event. The scheme utilizes a diamond plate as an x-ray transducer and a p-polarized probe beam.

  20. Response of surge protection devices to fast rising pulses

    NASA Technical Reports Server (NTRS)

    Mindel, I. N.

    1980-01-01

    Two types of lightning protection modules incorporating leadless (pill type) Zener like devices were evaluated with regard to their ability to suppress EMP induced transients. Two series of tests were performed to evaluate the ability of these modules to react to fast rate of rise ( 1Kv/ns) transients, and the attenuation introduced and the ability to limit damped sinusoid pulses which may be induced due to an EMP resulting from a nuclear detonation.

  1. Compton suppression through rise-time analysis.

    PubMed

    Selvi, S; Celiktas, C

    2007-11-01

    We studied Compton suppression for 60Co and 137Cs radioisotopes using a signal selection criterion based on contrasting the fall time of the signals composing the photo peak with those composing the Compton continuum. The fall time criterion is employed by using the pulse shape analysis observing the change in the fall times of the gamma-ray pulses. This change is determined by measuring the changes in the rise times related to the fall time of the scintillator and the timing signals related to the fall time of the input signals. We showed that Compton continuum suppression is achieved best via the precise timing adjustment of an analog rise-time analyzer connected to a NaI(Tl) scintillation spectrometer. PMID:17703943

  2. Short rise time intense electron beam generator

    DOEpatents

    Olson, C.L.

    1984-03-16

    A generator for producing an intense relativisitc electron beam having a subnanosecond current rise time includes a conventional generator of intense relativistic electrons feeding into a short electrically conductive drift tube including a cavity containing a working gas at a low enough pressure to prevent the input beam from significantly ionizing the working gas. Ionizing means such as a laser simultaneously ionize the entire volume of working gas in the cavity to generate an output beam having a rise time less than one nanosecond.

  3. Short rise time intense electron beam generator

    DOEpatents

    Olson, Craig L.

    1987-01-01

    A generator for producing an intense relativistic electron beam having a subnanosecond current rise time includes a conventional generator of intense relativistic electrons feeding into a short electrically conductive drift tube including a cavity containing a working gas at a low enough pressure to prevent the input beam from significantly ionizing the working gas. Ionizing means such as a laser simultaneously ionize the entire volume of working gas in the cavity to generate an output beam having a rise time less than one nanosecond.

  4. Dielectric-wall linear accelerator with a high voltage fast rise time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators

    DOEpatents

    Caporaso, George J.; Sampayan, Stephen E.; Kirbie, Hugh C.

    1998-01-01

    A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface.

  5. Dielectric-wall linear accelerator with a high voltage fast rise time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators

    DOEpatents

    Caporaso, G.J.; Sampayan, S.E.; Kirbie, H.C.

    1998-10-13

    A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface. 12 figs.

  6. Subnanosecond-rise-time, low-impedance pulse generator

    SciTech Connect

    Druce, R.; Vogtlin, G.

    1983-06-03

    This paper describes a fast rise, low-impedance pulse generator that has been developed at the Lawrence Livermore National Laboratory. The design specifications of this generator are: 50-kV operating voltage, 1-ohm output impedance, subnanosecond rise time, and a 2 to 10 nanosecond pulse length. High repetition rate is not required. The design chosen is a parallel-plate, folded Blumlein generator. A tack switch is utilized for its simple construction and high performance. The primary diagnostic is a capacitive voltage divider with a B probe used to measure the current waveform.

  7. Diffusion of fast rising strong magnetic fields into conductors

    NASA Astrophysics Data System (ADS)

    Labetskaya, N. A.; Oreshkin, V. I.; Chaikovsky, S. A.; Datsko, I. M.; Kuskova, N. I.; Rud, A. D.

    2014-11-01

    The basic processes occurring in a conductor exploding in a current skinning mode are the propagation of a nonlinear magnetic diffusion wave in the conductor and the formation of low-temperature plasma at its surface. An experimental study of the phenomenon of nonlinear magnetic diffusion into conductors in magnetic fields of induction rising at a rate up to 3·109 T/s was carried out on the MIG generator capable of producing a peak current up to 2.5 MA within a rise time of 100 ns. It has been found experimentally that the average velocity of a nonlinear magnetic diffusion wave in an aluminum conductor placed in a strong magnetic field (up to 300 T) rising at a high rate (on average, 3·109 T/s) is (2.7÷3.3)·105 cm/s. This is comparable to the velocity of sound in aluminum under normal conditions and reasonably agrees with predictions of numerical simulations.

  8. Crustal Thickness and Moho Character of the Fast-Spreading East Pacific Rise Between 9º37.5'N and 9º57'N From Poststack and Prestack Time Migrated 3D MCS data

    NASA Astrophysics Data System (ADS)

    Nedimovic, M. R.; Aghaei, O.; Carbotte, S. M.; Carton, H. D.; Canales, J. P.

    2014-12-01

    We measured crustal thickness and mapped Moho transition zone (MTZ) character over an 880 km2 section of the fast-spreading East Pacific Rise (EPR) using the first full 3D multichannel seismic (MCS) dataset collected across a mid-ocean ridge (MOR). The 9°42'-9°57'N area was initially investigated using 3D poststack time migration, which was followed by application of 3D prestack time migration (PSTM) to the whole dataset. This first attempt at applying 3D PSTM to MCS data from a MOR environment resulted in the most detailed reflection images of a spreading center to date. MTZ reflections are for the first time imaged below the ridge axis away from axial discontinuities indicating that Moho is formed at zero age at least at some sections of the MOR system. The average crustal thickness and crustal velocity derived from PSTM are 5920±320 m and 6320±290 m/s, respectively. The average crustal thickness varies little from Pacific to Cocos plate suggesting mostly uniform crustal production in the last ~180 Ka. However, the crust thins by ~400 m from south to north. The MTZ reflections were imaged within ~92% of the study area, with ~66% of the total characterized by impulsive reflections interpreted to originate from a thin MTZ and 26% characterized by diffusive reflections interpreted to originate from a thick MTZ. The MTZ is dominantly diffusive at the southern (9°37.5'-9°40'N) and northern (9°51'-9°57'N) ends of the study area, and it is impulsive in the central region (9°42'-9°51'N). No data were collected between 9°40'N and 9°42'N. More efficient mantle melt extraction is inferred within the central region with greater proportion of the lower crust accreted from the axial magma lens than within the northern and southern sections. This along-axis variation in the crustal accretion style may be caused by interaction between the melt sources for the ridge and the local seamounts, which are present within the northern and southern survey sections. Third

  9. Dependence of current rise time on laser-triggered discharge plasma

    NASA Astrophysics Data System (ADS)

    Lim, Soowon; Kamohara, Takashi; Hosseini, S. Hamid R.; Katsuki, Sunao

    2016-07-01

    A powerful, stable extreme ultraviolet (EUV) source is the most important component for EUV lithography and EUV mask inspection. Here, we investigate the characteristics of laser-triggered discharge plasma at three different current rise times, fast, middle and slow. A height-adjustable coaxial birdcage was used to change circuit inductance. The rise time was varied between 30 ns–55 ns with peak current of 10 kA. The time-integrated EUV (at 13.5 nm in 2% bandwidth) intensity for the fast rise time was found to be 55% stronger than that of the slow rise time despite its lower energy. A high-speed Mach–Zehnder interferogram and visible imaging of the pinch plasma were employed to discuss plasma compression processes qualitatively and quantitatively. Also discharge produced debris was investigated using a silicon-crystal witness plate. The fast rise current was found to have advantages such as lower debris, higher EUV intensity, and possibility of suppressing instability in comparison with the slow rise time. As expected, total debris amounts lessened proportionally to the primary charged energy, as found from a comparison of fast and slow rise currents.

  10. Mapping Rise Time Information with Down-Shift Analysis

    SciTech Connect

    Tunnell, T. W., Machorro, E. A., Diaz, A. B.

    2011-11-01

    These viewgraphs summarize the application of recent developments in digital down-shift (DDS) analysis of up converted PDV data to map out how well the PDV diagnostic would capture rise time information (mid point and rise time) in short rise time (<1 ns) shock events. The mapping supports a PDV vs VISAR challenge. The analysis concepts are new (~September FY 2011), simple, and run quickly, which makes them good tools to map out (with ~1 million Monte Carlo simulations) how well PDV captures rise time information as function of baseline velocity, rise time, velocity jump, and signal-to-noise ratios.

  11. Initiation of the Slow-Rise and Fast-Rise Phases of an Erupting Solar Filament by Localized Emerging Magnetic Field via Microflaring

    NASA Technical Reports Server (NTRS)

    Sterling, A. C.; Moore, R. L.; Harra, L. K.

    2006-01-01

    EUV data from EIT show that a filament of 2001 February 28 underwent a slow-rise phase lasting about 6 hrs, before rapidly erupting in a fast-rise phase. Concurrent images in soft X-rays (SXRs) from Yohkoh/SXT show that a series of three microflares, prominent in SXT images but weak in EIT approx.195 Ang EUV images, occurred near one end of the filament. The first and last microflares occurred respectively in conjunction with the start of the slow-rise phase and the start of the fast-rise phase, and the second microflare corresponded to a kink in the filament trajectory. Beginning within 10 hours of the start of the slow rise, new magnetic flux emerged at the location of the microflaring. This localized new flux emergence and the resulting microflares, consistent with reconnection between the emerging field and the sheared sigmoid core magnetic field holding the filament, apparently caused the slow rise of this field and the transition to explosive eruption. For the first time in such detail, the observations show this direct action of localized emerging flux in the progressive destabilization of a sheared core field in the onset of a coronal mass ejection (CME). Similar processes may have occurred in other recently-studied events, NASA supported this work through NASA SR&T and SEC GI grants.

  12. Detection of Sound Rise Time by Adults with Dyslexia

    ERIC Educational Resources Information Center

    Hamalainen, J.; Leppanen, P.H.T.; Torppa, M.; Muller, K.; Lyytinen, H.

    2005-01-01

    Low sensitivity to amplitude modulated (AM) sounds is reported to be associated with dyslexia. An important aspect of amplitude modulation cycles are the rise and fall times within the sound. In this study, simplified stimuli equivalent to just one cycle were used and sensitivity to varying rise times was explored. Adult participants with dyslexia…

  13. Flare Emission Onset in the Slow-Rise and Fast-Rise Phases of an Erupting Solar Filament Observed with TRACE

    NASA Technical Reports Server (NTRS)

    Sterling, A. C.; Moore, R. L.

    2005-01-01

    We observe the eruption of an active-region solar filament of 1998 July 11 using high time cadence and high spatial resolution EUV observations from the TRACE sareiii'ce, along with soft X-ray images from the soft X-ray telescope (SXT) on the Yohkoh satellite, hard X-ray fluxes from the BATSE instrument on the (CGRO) satellite and from the hard X-ray telescope (HXT) on Yohkoh, and ground-based magnetograms. We concentrate on the initiation of the eruption in an effort to understand the eruption mechanism. First the filament undergoes slow upward movement in a "slow rise" phase with an approximately constant velocity of approximately 15 km/s that lasts about 10-min, and then it erupts in a "fast-rise" phase, reaching a velocity of about 200 km/s in about 5-min, followed by a period of deceleration. EUV brightenings begin just before the start of the filament's slow rise, and remain immediately beneath the rising filament during the slow rise; initial soft X-ray brightenings occur at about the same time and location. Strong hard X-ray emission begins after the onset of the fast rise, and does not peak until the filament has traveled a substantial altitude (to a height about equal to the initial length of the erupting filament) beyond its initial location. Our observations are consistent with the slow-rise phase of the eruption resulting from the onset of "tether cutting" reconnection between magnetic fields beneath the filament, and the fast rise resulting from an explosive increase in the reconnection rate or by catastrophic destabilization of the overlying filament-carrying fields. About two days prior to the event new flux emerged near the location of the initial brightenings, and this recently- emerged flux could have been a catalyst for initiating the tether-cutting reconnection. With the exception of the initial slow rise, our findings qualitatively agree with the prediction for erupting-flux-rope height as a function of time in a model discussed by Chen

  14. A sub-nanosecond rise time intense electron beam source

    NASA Astrophysics Data System (ADS)

    Kumar, R.; Chandra, R.; Mitra, S.; Beg, M. D.; Sharma, D. K.; Sharma, A.; Mittal, K. C.

    2014-04-01

    This paper presents the design and development of a 75 kV, 55 A, 2 nanosecond duration, <= 850 ps rise time, single shot, intense ( >= 100 A/cm2) electron beam source and also the measurement technique adopted in sub-nanosecond regime. A 200 kV (nanosecond pulse) coaxial pulse forming line (PFL) based pulser is designed to drive a cold cathode explosive emission electron gun. The electron gun diode consists with a planer graphite cathode, which has the emission area of 8 mm diameter and a SS 304L anode mesh. Vacuum is achieved of the order of 3.5e-5 mbar by using a diffusion pump, backed by rotary pump. At the diagnostic side for diode voltage measurement a fast response copper sulphate aqueous solution resistive voltage divider is designed and implemented. For the beam current diagnostic a graphite Faraday cup is designed with taking care of response time in GHz (1.0-3.0 GHz) regime. The circuit diagram, voltage and current waveforms and the experimental setup is presented.

  15. An evaluation of rise time characterization and prediction methods

    NASA Technical Reports Server (NTRS)

    Robinson, Leick D.

    1994-01-01

    One common method of extrapolating sonic boom waveforms from aircraft to ground is to calculate the nonlinear distortion, and then add a rise time to each shock by a simple empirical rule. One common rule is the '3 over P' rule which calculates the rise time in milliseconds as three divided by the shock amplitude in psf. This rule was compared with the results of ZEPHYRUS, a comprehensive algorithm which calculates sonic boom propagation and extrapolation with the combined effects of nonlinearity, attenuation, dispersion, geometric spreading, and refraction in a stratified atmosphere. It is shown there that the simple empirical rule considerably overestimates the rise time estimate. In addition, the empirical rule does not account for variations in the rise time due to humidity variation or propagation history. It is also demonstrated that the rise time is only an approximate indicator of perceived loudness. Three waveforms with identical characteristics (shock placement, amplitude, and rise time), but with different shock shapes, are shown to give different calculated loudness. This paper is based in part on work performed at the Applied Research Laboratories, the University of Texas at Austin, and supported by NASA Langley.

  16. SNLS: Supernova Rise Times from the SNLS Sample

    NASA Astrophysics Data System (ADS)

    Conley, A.; Howell, D. A.; Howes, A.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R. G.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I.; Lafoux, H.; Neill, J. D.; Pain, R.; Palanque-Delabrouille, N.; Perett, K.; Pritchet, C. J.; Regnault, N.; Rich, J.; Sullivan, M.; Taillet, R.; Baumont, S.; Bronder, J.; Lusset, V.; Ripoche, P.; Mourao, A.; Perlmutter, S.; Tao, C.

    2005-12-01

    Type Ia supernovae (SNe Ia) provide the most direct evidence for the acceleration of the Universe. This evidence relies on a comparison between the luminosities of distant and nearby SNe Ia, and hence is potentially sensitive to any evolution in the mean lightcurve properties between these two samples. One method for testing for the presence of such effects is to measure and compare the rise time, which is the time between explosion and maximum luminosity, of the two samples. The Supernova Legacy Survey provides an excellent data sample for the analysis of this issue, since it's 'rolling search' nature yields lightcurves which are well sampled prior to maximum light. Here we discuss measurements of the rise time from SNLS data and what they can tell us about evolutionary effects.

  17. A note on some statistical properties of rise time parameters used in muon arrival time measurements

    NASA Technical Reports Server (NTRS)

    Vanderwalt, D. J.; Devilliers, E. J.

    1985-01-01

    Most investigations of the muon arrival time distribution in EAS during the past decade made use of parameters which can collectively be called rise time parameters. The rise time parameter T sub A/B is defined as the time taken for the integrated pulse from a detector to rise from A% to B% of its full amplitude. The use of these parameters are usually restricted to the determination of the radial dependence thereof. This radial dependence of the rise time parameters are usually taken as a signature of the particle interaction characteristics in the shower. As these parameters have a stochastic nature, it seems reasonable that one should also take notice of this aspect of the rise time parameters. A statistical approach to rise time parameters is presented.

  18. Neural processing of amplitude and formant rise time in dyslexia.

    PubMed

    Peter, Varghese; Kalashnikova, Marina; Burnham, Denis

    2016-06-01

    This study aimed to investigate how children with dyslexia weight amplitude rise time (ART) and formant rise time (FRT) cues in phonetic discrimination. Passive mismatch responses (MMR) were recorded for a/ba/-/wa/contrast in a multiple deviant odd-ball paradigm to identify the neural response to cue weighting in 17 children with dyslexia and 17 age-matched control children. The deviant stimuli had either partial or full ART or FRT cues. The results showed that ART did not generate an MMR in either group, whereas both partial and full FRT cues generated MMR in control children while only full FRT cues generated MMR in children with dyslexia. These findings suggest that children, both controls and those with dyslexia, discriminate speech based on FRT cues and not ART cues. However, control children have greater sensitivity to FRT cues in speech compared to children with dyslexia. PMID:27017263

  19. Fission-neutrons source with fast neutron-emission timing

    NASA Astrophysics Data System (ADS)

    Rusev, G.; Baramsai, B.; Bond, E. M.; Jandel, M.

    2016-05-01

    A neutron source with fast timing has been built to help with detector-response measurements. The source is based on the neutron emission from the spontaneous fission of 252Cf. The time is provided by registering the fission fragments in a layer of a thin scintillation film with a signal rise time of 1 ns. The scintillation light output is measured by two silicon photomultipliers with rise time of 0.5 ns. Overall time resolution of the source is 0.3 ns. Design of the source and test measurements using it are described. An example application of the source for determining the neutron/gamma pulse-shape discrimination by a stilbene crystal is given.

  20. A LUMINOUS, FAST RISING UV-TRANSIENT DISCOVERED BY ROTSE: A TIDAL DISRUPTION EVENT?

    SciTech Connect

    Vinkó, J.; Wheeler, J. C.; Chatzopoulos, E.; Marion, G. H.; Yuan, F.; Akerlof, C.; Quimby, R. M.; Ramirez-Ruiz, E.; Guillochon, J.

    2015-01-01

    We present follow-up observations of an optical transient (OT) discovered by ROTSE on 2009 January 21. Photometric monitoring was carried out with ROTSE-IIIb in the optical and Swift in the UV up to +70 days after discovery. The light curve showed a fast rise time of ∼10 days followed by a steep decline over the next 60 days, which was much faster than that implied by {sup 56}Ni—{sup 56}Co radioactive decay. The Sloan Digital Sky Survey Data Release 10 database contains a faint, red object at the position of the OT, which appears slightly extended. This and other lines of evidence suggest that the OT is of extragalactic origin, and this faint object is likely the host galaxy. A sequence of optical spectra obtained with the 9.2 m Hobby-Eberly Telescope between +8 and +45 days after discovery revealed a hot, blue continuum with no visible spectral features. A few weak features that appeared after +30 days probably originated from the underlying host. Fitting synthetic templates to the observed spectrum of the host galaxy revealed a redshift of z = 0.19. At this redshift, the peak magnitude of the OT is close to –22.5, similar to the brightest super-luminous supernovae; however, the lack of identifiable spectral features makes the massive stellar death hypothesis less likely. A more plausible explanation appears to be the tidal disruption of a Sun-like star by the central supermassive black hole. We argue that this transient likely belongs to a class of super-Eddington tidal disruption events.

  1. DOI Determination by Rise Time Discrimination in Single-Ended Readout for TOF PET Imaging

    PubMed Central

    Wiener, R.I.; Surti, S.; Karp, J.S.

    2013-01-01

    Clinical TOF PET systems achieve detection efficiency using thick crystals, typically of thickness 2–3cm. The resulting dispersion in interaction depths degrades spatial resolution for increasing radial positions due to parallax error. Furthermore, interaction depth dispersion results in time pickoff dispersion and thus in degraded timing resolution, and is therefore of added concern in TOF scanners. Using fast signal digitization, we characterize the timing performance, pulse shape and light output of LaBr3:Ce, CeBr3 and LYSO. Coincidence timing resolution is shown to degrade by ~50ps/cm for scintillator pixels of constant cross section and increasing length. By controlling irradiation depth in a scintillator pixel, we show that DOI-dependence of time pickoff is a significant factor in the loss of timing performance in thick detectors. Using the correlated DOI-dependence of time pickoff and charge collection, we apply a charge-based correction to the time pickoff, obtaining improved coincidence timing resolution of <200ps for a uniform 4×4×30mm3 LaBr3 pixel. In order to obtain both DOI identification and improved timing resolution, we design a two layer LaBr3[5%Ce]/LaBr3[30%Ce] detector of total size 4×4×30mm3, exploiting the dependence of scintillator rise time on [Ce] in LaBr3:Ce. Using signal rise time to determine interaction layer, excellent interaction layer discrimination is achieved, while maintaining coincidence timing resolution of <250ps and energy resolution <7% using a R4998 PMT. Excellent layer separation and timing performance is measured with several other commercially-available TOF photodetectors, demonstrating the practicality of this design. These results indicate the feasibility of rise time discrimination as a technique for measuring event DOI while maintaining sensitivity, timing and energy performance, in a well-known detector architecture. PMID:24403611

  2. Supernova Rates, Rise-Times, and their Relations to Progenitors

    NASA Astrophysics Data System (ADS)

    Gonzalez Gaitan, Santiago

    Supernovae are fundamental in astronomy: they inject high mass elements into the interstellar medium enriching the chemistry of galaxies, they feed processes of star formation and active galactic nuclei, and they have been a key for the developments in cosmology of the past decades. This dissertation presents a set of subluminous type Ia supernovae (SNe Ia) at z > 0.1 from the Supernova Legacy Survey (SNLS). These faint and short-lived transients are found in massive and passive host galaxies. We measure a volumetric rate as a function of redshift that is different from the normal SN Ia population. The observations point towards a long delay time since the birth of the progenitors systems and argue for progenitor stars of initial low mass. We calculate a stretch-corrected rise-time since explosion to maximum brightness for different sets of SNe Ia. We find that a fiducial 17 day quadratic rise is sufficient to explain all SNe Ia, including subluminous ones, arguing for their homogeneity throughout the entire light-curve. Subluminous SNe Ia are powered by as little as 0.05 solar masses of radioactive nickel synthesized in the explosion. Theoretical models need to explain these challenging weak explosions within the framework of SNe Ia. Finally, we develop one of the first robust automated techniques to identify plateau supernovae (SNe IIP) in large photometric transient surveys. This simple method was tested with a variety of real and simulated SN samples and proved to be effective across different redshifts. Such a photometric typing will be of great power for coming surveys and will allow numerous scientific studies of SNe IIP.

  3. Rise Times of Solar Energetic Particle Events and Speeds of CMEs

    NASA Astrophysics Data System (ADS)

    Kahler, S.; Reames, D.

    2002-12-01

    Gradual solar energetic particle (SEP) events are assumed to be produced in coronal and interplanetary shocks driven by fast coronal mass ejections (CMEs). These fast CMEs are decelerated as they move through the slower ambient solar wind. However, the Alfven speed is decreasing with increasing distance. Faster CMEs may therefore continue to drive strong shocks for longer characteristic times than do the slower CMEs, such that shock production and injection of SEPs of a given energy will also continue longer with the faster CMEs. We test this proposition observationally by comparing the times to maxima of 20 MeV SEP events with the observed speeds of associated CMEs. The SEP/CME events are sorted by solar longitude to factor out the longitudinal dependence of the SEP rise times. A preliminary analysis comparing 20 MeV protons from the GSFC EPACT detector on the Wind satellite with CMEs observed by the LASCO coronagraph on the SOHO spacecraft showed a correlation between SEP rise times and CME speeds. We expand the database to include the 1996-2001 period for a more definitive test of the correlation. The implications of the results will be discussed.

  4. Fast timing methods for semiconductor detectors. Revision

    SciTech Connect

    Spieler, H.

    1984-10-01

    This tutorial paper discusses the basic parameters which determine the accuracy of timing measurements and their effect in a practical application, specifically timing with thin-surface barrier detectors. The discussion focusses on properties of the detector, low-noise amplifiers, trigger circuits and time converters. New material presented in this paper includes bipolar transistor input stages with noise performance superior to currently available FETs, noiseless input terminations in sub-nanosecond preamplifiers and methods using transmission lines to couple the detector to remotely mounted preamplifiers. Trigger circuits are characterized in terms of effective rise time, equivalent input noise and residual jitter.

  5. Optical visualization and electrical characterization of fast-rising pulsed dielectric barrier discharge for airflow control applications

    NASA Astrophysics Data System (ADS)

    Benard, Nicolas; Zouzou, Nourredine; Claverie, Alain; Sotton, Julien; Moreau, Eric

    2012-02-01

    Flow control consists of manipulating flows in an effective and robust manner to improve the global performances of transport systems or industrial processes. Plasma technologies, and particularly surface dielectric barrier discharge (DBD), can be a good candidate for such purpose. The present experimental study focuses on optical and electrical characterization of plasma sheet formed by applying a pulse of voltage with rising and falling periods of 50 ns for a typical surface DBD geometry. Positive and negative polarities are compared in terms of current behavior, deposited energy, fast-imaging of the plasma propagation, and resulting modifications of the surrounding medium by using shadowgraphy acquisitions. Positive and negative pulses of voltage produce streamers and corona type plasma, respectively. Both of them result in the production of a localized pressure wave propagating in the air with a speed maintained at 343 m/s (measurements at room temperature of 20 °C). This suggests that the produced pressure wave can be considered as a propagating sound wave. The intensity of the pressure wave is directly connected to the dissipated energy at the dielectric wall with a linear increase with the applied voltage amplitude and a strong dependence toward the rising time. At constant voltage amplitude, the pressure wave is reinforced by using a positive pulse. The present investigation also reveals that rising and decaying periods of a single pulse of voltage result in two distinct pressure waves. As a result, superposition or successive pressure wave can be produced by adjusting the width of the pulse.

  6. High-power megavolt pulse generator with nanosecond rise time

    SciTech Connect

    Basov, G.F.; Bastrikov, A.N.; Koval`chuk, B.M.

    1995-10-01

    A pulse generator with a power of 0.1 TW, an amplitude of up to 2 MV and {approximately}1.5-nsec rise time is described. A Marx voltage pulse generator charges a low-inductance capacitor (1.8 nF) and a radial line (0.9 nF) to a voltage of {approximately}2 MV in 200 nsec. At the peak voltage, a water switch is actuated at the center of the radial line resulting in {approximately} 2.5-MV voltage pulse at the end of the line. This pulse propagates along the oil-insulated line. The line is connected to an oil-filled peaking switch with a metal diaphragm, which reduces the transfer capacitance of the discharge gap to 5 pF to match the radial-line wave impedance to the load connected to the switch output. A crossover switch may be used when operating in the short-pulse mode. A pulse with a width of up to 20 nsec has been generated across a load equivalent matched to the line.

  7. High voltage electrical amplifier having a short rise time

    DOEpatents

    Christie, David J.; Dallum, Gregory E.

    1991-01-01

    A circuit, comprising an amplifier and a transformer is disclosed that produces a high power pulse having a fast response time, and that responds to a digital control signal applied through a digital-to-analog converter. The present invention is suitable for driving a component such as an electro-optic modulator with a voltage in the kilovolt range. The circuit is stable at high frequencies and during pulse transients, and its impedance matching circuit matches the load impedance with the output impedance. The preferred embodiment comprises an input stage compatible with high-speed semiconductor components for amplifying the voltage of the input control signal, a buffer for isolating the input stage from the output stage; and a plurality of current amplifiers connected to the buffer. Each current amplifier is connected to a field effect transistor (FET), which switches a high voltage power supply to a transformer which then provides an output terminal for driving a load. The transformer comprises a plurality of transmission lines connected to the FETs and the load. The transformer changes the impedance and voltage of the output. The preferred embodiment also comprises a low voltage power supply for biasing the FETs at or near an operational voltage.

  8. Fluid flow patterns in fast spreading East Pacific Rise crust exposed at Hess Deep

    NASA Astrophysics Data System (ADS)

    Gillis, Kathryn M.; Muehlenbachs, Karlis; Stewart, Michael; Gleeson, Thomas; Karson, Jeffrey

    2001-11-01

    Tectonic exposures of a volcanic sequence and sheeted dike complex over a 4-km-wide region at Hess Deep (equatorial Pacific) reveal significant spatial heterogeneity (10-103 m) in the extent and nature of hydrothermal alteration in young, fast spreading East Pacific Rise crust. The volcanic sequence is fairly uniformly altered, with only minor oxidation and alteration to clay minerals. Sheeted dikes in the eastern part of the field area are highly fractured with narrow intervals of intact dikes that dip up to 60°. Their alteration characteristics show a simple depth trend such that with increasing depth the dominant secondary mafic mineral changes from chlorite to amphibole, clinopyroxene replacement increases (<20% to >40%), whole rock δ18O values decreases (4.4-5.5‰ to 3.5-4.5‰), and calculated peak metamorphic temperatures increase (˜250°C to 450°-700°C). Within the deepest dikes, localized zones up to 400-m-wide are chlorite-rich and have low-δ18O (2.9-4.1‰) and low peak metamorphic temperatures (˜345°C). These alteration patterns likely formed within broad recharge zones whereby the low-δ18O zones developed in the regions with the highest fluid flux. In the west, massive, slightly rotated sheeted dikes near the volcanic-sheeted dike transition are δ18O and Cu depleted and display higher peak temperatures (≥345°C) than elsewhere in the shallow dikes. These characteristics are consistent with formation within a high temperature, hydrothermal discharge zone. We propose that the spreading history of a fast spreading ridge segment can create significant spatial heterogeneity in fluid flow and alteration patterns within sheeted dike complexes, similar to those preserved in many ophiolites.

  9. Measurement of breakdown characteristics of SF 6 insulated spark gaps at fast rising overvoltages

    NASA Astrophysics Data System (ADS)

    Machlitt, N.; Assmann, W.; Skorka, S. J.

    1988-05-01

    A new experimental setup has been designed to extend previous investigations of the time response at large overvoltages of SF 6 insulated spark gaps to a higher voltage range. The setup consists of a double gap coaxial transmission line, the first gap acting as fast switch, the second one as a test gap. The gap ratio defines the overvoltages. Technical data and features of the discharge-line and the fast capacitive pickups are presented. First experiments were done with maximum pulse voltages of 140 kV and slopes of approximately 300 kV/ns. The gas pressure varied between 6 and 8 bar and the gap width of the test gap reached a value of 1.6 mm.

  10. THE TEMPORAL AND SPECTRAL CHARACTERISTICS OF 'FAST RISE AND EXPONENTIAL DECAY' GAMMA-RAY BURST PULSES

    SciTech Connect

    Peng, Z. Y.; Ma, L.; Yin, Y.; Bi, X. W.; Zhao, X. H.; Bao, Y. Y. E-mail: astromali@126.co

    2010-08-01

    In this paper, we have analyzed the temporal and spectral behavior of 52 fast rise and exponential decay (FRED) pulses in 48 long-duration gamma-ray bursts (GRBs) observed by the CGRO/BATSE, using a pulse model with two shape parameters and the Band model with three shape parameters, respectively. It is found that these FRED pulses are distinguished both temporally and spectrally from those in the long-lag pulses. In contrast to the long-lag pulses, only one parameter pair indicates an evident correlation among the five parameters, which suggests that at least four parameters are needed to model burst temporal and spectral behavior. In addition, our studies reveal that these FRED pulses have the following correlated properties: (1) long-duration pulses have harder spectra and are less luminous than short-duration pulses and (2) the more asymmetric the pulses are, the steeper are the evolutionary curves of the peak energy (E{sub p}) in the {nu}f{sub {nu}} spectrum within the pulse decay phase. Our statistical results give some constraints on the current GRB models.

  11. Time of flight fast neutron radiography

    NASA Astrophysics Data System (ADS)

    Loveman, R.; Bendahan, J.; Gozani, T.; Stevenson, J.

    1995-05-01

    Neutron radiography with fast or thermal neutrons is a standard technique for non-destructive testing (NDT). Here we report results for fast neutron radiography both as an adjunct to pulsed fast neutron analysis (PFNA) and as a stand-alone method for NDT. PFNA is a new technique for utilizing a collimated pulsed neutron beam to interrogate items and determine their elemental composition. By determining the time of flight for gamma-rays produced by (n,n' gamma X) reactions, a three dimensional image can be produced. Neutron radiography data taken with the same beam provides an important constraint for image reconstruction, and in particular is important in inferring the amount of hydrogen within the interrogated item. As a stand-alone device, the radiography measurement can be used to image items as large as cargo containers as long as their density is not too high. The use of a pulsed beam gives the further advantage of a time of flight measurement on the transmitted neutrons. By gating the radiography signal on the time of flight appropriate to the energy of the primary neutrons, most build-up from scattered neutrons can be eliminated. The pulsed beam also greatly improves the signal to background and extends the range of the neutron radiography. Simulation results will be presented which display the advantage of this constraint in particular for statistically limited data. Experimental results will be presented which show some of the limitations likely in a PFNA system utilizing neutron radiography data. Experimental and simulation results will demonstrate possible uses for this type of radiographic data in identifying contraband substances such as drugs.

  12. Estimating optimal time for fast chromatographic separations.

    PubMed

    Welch, Christopher J; Regalado, Erik L

    2014-09-01

    The term t(min cc) provides a ready estimate of the shortest time that can be obtained by "column cutting" for baseline resolution of two components showing excess chromatographic resolution. While actual column cutting is impractical, the t(min cc) value is shown to be closely related to the minimum separation time obtainable by adjusting other parameters such as flow rate, mobile phase composition, and temperature, affording scientists interested in the development of fast chromatographic separations a convenient tool for estimating the minimum separation time that can be obtained by modifying a given method development screening result. Furthermore, the relationship between t(min cc) and the minimum separation time obtainable by adjusting other parameters is shown to be dependent on the speed of the screening method, with aggressive screening gradients affording t(min cc) estimates that match the actual minimum separation time, and "lazy" screening gradients affording t(min cc) values that overestimate minimum separation time. Consequently, the analysis of the relationship between t(min cc) and actual minimum separation time may be a useful tool for determining the "fitness" of method development screening methods. PMID:24995384

  13. Skin explosion of double-layer conductors in fast-rising high magnetic fields

    SciTech Connect

    Chaikovsky, S. A. Datsko, I. M.; Labetskaya, N. A.; Ratakhin, N. A.

    2014-04-15

    An experiment has been performed to study the electrical explosion of thick cylindrical conductors using the MIG pulsed power generator capable of producing a peak current of 2.5 MA within 100 ns rise time. The experimental goal was to compare the skin explosion of a solid conductor with that of a double-layer conductor whose outer layer had a lower conductivity than the inner one. It has been shown that in magnetic fields of peak induction up to 300 T and average induction rise rate 3 × 10{sup 9} T/s, the double-layer structure of a conductor makes it possible to achieve higher magnetic induction at the conductor surface before it explodes. This can be accounted for, in particular, by the reduction of the ratio of the Joule heat density to the energy density of the magnetic field at the surface of a double-layer conductor due to redistribution of the current density over the conductor cross section.

  14. RISE/FALL TIME ENHANCEMENT OF THE SPALLATION NEUTRON SOURCE LINAC LEBT CHOPPER SYSTEM

    SciTech Connect

    Peplov, Vladimir V; Saethre, Robert B

    2013-01-01

    The Spallation Neutron Source (SNS) Linac Low Energy Beam Transport (LEBT) chopper system provides fast chopping of the H- ion beam in the LEBT structure. Four identical pulsed power supplies (pulsers) create a series of 2.5 kV pulses to the four deflection electrodes floating on the focusing voltage of -50 kV. Each pulser is connected to the electrode through the network which consists of high voltage (HV) cables, a blocking capacitor, HV feed-through connectors, current-limiting resistors and transient voltage suppressors. Effective beam chopping requires minimal rise/fall time of the rectangular HV pulses on the load. In the present configuration these values are approximately 100 ns. Methods of reducing rise/fall time on the LEBT electrodes are discussed. Results of simulation and comparative measurements of the original and upgraded system on the test stand are presented. Furthermore, the effect of these changes on reliability degradation caused by arcing in the LEBT structure is discussed.

  15. A fast rise-rate, adjustable-mass-bit gas puff valve for energetic pulsed plasma experiments

    SciTech Connect

    Loebner, Keith T. K. Underwood, Thomas C.; Cappelli, Mark A.

    2015-06-15

    A fast rise-rate, variable mass-bit gas puff valve based on the diamagnetic repulsion principle was designed, built, and experimentally characterized. The ability to hold the pressure rise-rate nearly constant while varying the total overall mass bit was achieved via a movable mechanical restrictor that is accessible while the valve is assembled and pressurized. The rise-rates and mass-bits were measured via piezoelectric pressure transducers for plenum pressures between 10 and 40 psig and restrictor positions of 0.02-1.33 cm from the bottom of the linear restrictor travel. The mass-bits were found to vary linearly with the restrictor position at a given plenum pressure, while rise-rates varied linearly with plenum pressure but exhibited low variation over the range of possible restrictor positions. The ability to change the operating regime of a pulsed coaxial plasma deflagration accelerator by means of altering the valve parameters is demonstrated.

  16. A fast rise-rate, adjustable-mass-bit gas puff valve for energetic pulsed plasma experiments

    NASA Astrophysics Data System (ADS)

    Loebner, Keith T. K.; Underwood, Thomas C.; Cappelli, Mark A.

    2015-06-01

    A fast rise-rate, variable mass-bit gas puff valve based on the diamagnetic repulsion principle was designed, built, and experimentally characterized. The ability to hold the pressure rise-rate nearly constant while varying the total overall mass bit was achieved via a movable mechanical restrictor that is accessible while the valve is assembled and pressurized. The rise-rates and mass-bits were measured via piezoelectric pressure transducers for plenum pressures between 10 and 40 psig and restrictor positions of 0.02-1.33 cm from the bottom of the linear restrictor travel. The mass-bits were found to vary linearly with the restrictor position at a given plenum pressure, while rise-rates varied linearly with plenum pressure but exhibited low variation over the range of possible restrictor positions. The ability to change the operating regime of a pulsed coaxial plasma deflagration accelerator by means of altering the valve parameters is demonstrated.

  17. Fast Rise Exponential Decay (FRED) Gamma-Ray Bursts and the Fluence Duration Bias

    NASA Astrophysics Data System (ADS)

    Young, K. C.; Hakkila, J.; Giblin, T. W.

    2003-05-01

    The fluences and durations of gamma-ray bursts (GRBs) can be systematically underestimated for low signal-to-noise ratios. This is the result of a human operator selecting a time interval shorter than the burst interval, effectively ignoring burst flux in the fluence calculation. The gradual rise and decay of the FRED-type GRBs are especially susceptible to this bias. Because of the large number of FREDs in the BATSE catalogue, a series of Monte Carlo simulations of hypothetical FREDs have been analyzed. By varying the parameters of the Norris et al. pulse model, the properties of those FREDs most susceptible to the fluence duration bias have been identified. This work is funded by NASA grant NRA-98-OSS-03 and NSF grant AST00-98499.

  18. Evaluation of Fast-Time Wake Vortex Prediction Models

    NASA Technical Reports Server (NTRS)

    Proctor, Fred H.; Hamilton, David W.

    2009-01-01

    Current fast-time wake models are reviewed and three basic types are defined. Predictions from several of the fast-time models are compared. Previous statistical evaluations of the APA-Sarpkaya and D2P fast-time models are discussed. Root Mean Square errors between fast-time model predictions and Lidar wake measurements are examined for a 24 hr period at Denver International Airport. Shortcomings in current methodology for evaluating wake errors are also discussed.

  19. Fast time-resolved electrostatic force microscopy: Achieving sub-cycle time resolution.

    PubMed

    Karatay, Durmus U; Harrison, Jeffrey S; Glaz, Micah S; Giridharagopal, Rajiv; Ginger, David S

    2016-05-01

    The ability to measure microsecond- and nanosecond-scale local dynamics below the diffraction limit with widely available atomic force microscopy hardware would enable new scientific studies in fields ranging from biology to semiconductor physics. However, commercially available scanning-probe instruments typically offer the ability to measure dynamics only on time scales of milliseconds to seconds. Here, we describe in detail the implementation of fast time-resolved electrostatic force microscopy using an oscillating cantilever as a means to measure fast local dynamics following a perturbation to a sample. We show how the phase of the oscillating cantilever relative to the perturbation event is critical to achieving reliable sub-cycle time resolution. We explore how noise affects the achievable time resolution and present empirical guidelines for reducing noise and optimizing experimental parameters. Specifically, we show that reducing the noise on the cantilever by using photothermal excitation instead of piezoacoustic excitation further improves time resolution. We demonstrate the discrimination of signal rise times with time constants as fast as 10 ns, and simultaneous data acquisition and analysis for dramatically improved image acquisition times. PMID:27250430

  20. Fast time-resolved electrostatic force microscopy: Achieving sub-cycle time resolution

    NASA Astrophysics Data System (ADS)

    Karatay, Durmus U.; Harrison, Jeffrey S.; Glaz, Micah S.; Giridharagopal, Rajiv; Ginger, David S.

    2016-05-01

    The ability to measure microsecond- and nanosecond-scale local dynamics below the diffraction limit with widely available atomic force microscopy hardware would enable new scientific studies in fields ranging from biology to semiconductor physics. However, commercially available scanning-probe instruments typically offer the ability to measure dynamics only on time scales of milliseconds to seconds. Here, we describe in detail the implementation of fast time-resolved electrostatic force microscopy using an oscillating cantilever as a means to measure fast local dynamics following a perturbation to a sample. We show how the phase of the oscillating cantilever relative to the perturbation event is critical to achieving reliable sub-cycle time resolution. We explore how noise affects the achievable time resolution and present empirical guidelines for reducing noise and optimizing experimental parameters. Specifically, we show that reducing the noise on the cantilever by using photothermal excitation instead of piezoacoustic excitation further improves time resolution. We demonstrate the discrimination of signal rise times with time constants as fast as 10 ns, and simultaneous data acquisition and analysis for dramatically improved image acquisition times.

  1. Fast Simulation of Tsunamis in Real Time

    NASA Astrophysics Data System (ADS)

    Fryer, G. J.; Wang, D.; Becker, N. C.; Weinstein, S. A.; Walsh, D.

    2011-12-01

    The U.S. Tsunami Warning Centers primarily base their wave height forecasts on precomputed tsunami scenarios, such as the SIFT model (Standby Inundation Forecasting of Tsunamis) developed by NOAA's Center for Tsunami Research. In SIFT, tsunami simulations for about 1600 individual earthquake sources, each 100x50 km, define shallow subduction worldwide. These simulations are stored in a database and combined linearly to make up the tsunami from any great earthquake. Precomputation is necessary because the nonlinear shallow-water wave equations are too time consuming to compute during an event. While such scenario-based models are valuable, they tacitly assume all energy in a tsunami comes from thrust at the décollement. The thrust assumption is often violated (e.g., 1933 Sanriku, 2007 Kurils, 2009 Samoa), while a significant number of tsunamigenic earthquakes are completely unrelated to subduction (e.g., 1812 Santa Barbara, 1939 Accra, 1975 Kalapana). Finally, parts of some subduction zones are so poorly defined that precomputations may be of little value (e.g., 1762 Arakan, 1755 Lisbon). For all such sources, a fast means of estimating tsunami size is essential. At the Pacific Tsunami Warning Center, we have been using our model RIFT (Real-time Inundation Forecasting of Tsunamis) experimentally for two years. RIFT is fast by design: it solves only the linearized form of the equations. At 4 arc-minutes resolution calculations for the entire Pacific take just a few minutes on an 8-processor Linux box. Part of the rationale for developing RIFT was earthquakes of M 7.8 or smaller, which approach the lower limit of the more complex SIFT's abilities. For such events we currently issue a fixed warning to areas within 1,000 km of the source, which typically means a lot of over-warning. With sources defined by W-phase CMTs, exhaustive comparison with runup data shows that we can reduce the warning area significantly. Even before CMTs are available, we routinely run models

  2. Testing Time Dilation on Fast Ion Beams

    NASA Astrophysics Data System (ADS)

    Saathoff, G.; Reinhardt, S.; Bernhardt, B.; Holzwarth, R.; Udem, T.; Hänsch, T. W.; Bing, D.; Schwalm, D.; Wolf, A.; Botermann, B.; Karpuk, S.; Novotny, C.; Nörtershäuser, W.; Huber, G.; Geppert, C.; Kühl, T.; Stöhlker, T.; Rempel, T.; Gwinner, G.

    2011-12-01

    We report the status of an experimental test of special-relativistic time dilation. Following an idea of Ives and Stilwell in 1938, we measure the forward and backward Doppler shifts of an electronic transition of fast moving ions, using high-precision laser spectroscopy. From these Doppler shifts both the ion velocity β = υ/c and the time dilation factor γ = γ {SR} (1 + hat α β 2 ) can be derived for testing Special Relativity. From measurements based on saturation spectroscopy on lithium ions stored at β = 0.03 and β = 0.06, we achieved an upper limit for deviation from Special Relativity of <=ft| {hat α } ; | \\underline < 8 × 10{ - 8} . Recent measurements on a β = 0.338 Li+ beam show similar sensitivity and promise an improvement by at least one order of magnitude. Finally we discuss present sensitivities to various coefficients in the photon and particle sector of the Standard-Model Extension, as well as possible modifications of the experiment for the test of further, hitherto unbounded, coefficients.

  3. Abrupt rise of new machine ecology beyond human response time

    PubMed Central

    Johnson, Neil; Zhao, Guannan; Hunsader, Eric; Qi, Hong; Johnson, Nicholas; Meng, Jing; Tivnan, Brian

    2013-01-01

    Society's techno-social systems are becoming ever faster and more computer-orientated. However, far from simply generating faster versions of existing behaviour, we show that this speed-up can generate a new behavioural regime as humans lose the ability to intervene in real time. Analyzing millisecond-scale data for the world's largest and most powerful techno-social system, the global financial market, we uncover an abrupt transition to a new all-machine phase characterized by large numbers of subsecond extreme events. The proliferation of these subsecond events shows an intriguing correlation with the onset of the system-wide financial collapse in 2008. Our findings are consistent with an emerging ecology of competitive machines featuring ‘crowds' of predatory algorithms, and highlight the need for a new scientific theory of subsecond financial phenomena. PMID:24022120

  4. Coefficient of restitution dependence of intruder rise time in two-dimensional Brazil-nut effect

    NASA Astrophysics Data System (ADS)

    Kesuma, T.; Aji, D. P. Purwa; Viridi, S.; Suprijadi

    2016-04-01

    Brazil-Nut Effect (BNE) is a granular material phenomenon, where larger grains (usually known as intruder) rise to the top when the granular system vibrated. We observe a single intruder rise time of BNE phenomenon in a two-dimensional molecular dynamics simulation of hard spheres collision scheme. Some experiments have shown that some granular properties, such as size and density ratio, play an important role to determine the rise time. However, other property, such as coefficients of restitution, is considered not to have a measurable impact. We explore the intruder inelasticity dependence of the rise time by varying its coefficient of restitution. We found that the intruder rise time tends to be flat for relatively high coefficient of restitution and increases exponentially below a certain deflecting point for low coefficient of restitution. This holds for specific mass ratio.

  5. Note: A rectangular pulse generator for 50 kV voltage, 0.8 ns rise time, and 10 ns pulse width based on polymer-film switch.

    PubMed

    Wu, Hanyu; Zhang, Xinjun; Sun, Tieping; Zeng, Zhengzhong; Cong, Peitian; Zhang, Shaoguo

    2015-10-01

    In this article, we describe a rectangular pulse generator, consisting of a polymer-film switch, a tri-plate transmission line, and parallel post-shaped ceramic resistor load, for 50-kV voltage, 0.8-ns rise time, and 10-ns width. The switch and resistors are arranged in atmospheric air and the transmission line can work in atmospheric air or in transformer oil to change the pulse width from 6.7 ns to 10 ns. The fast switching and low-inductance characteristics of the polymer-film switch ensure the fast rising wavefront of <1 ns. This generator can be applied in the calibration of nanosecond voltage dividers and used for electromagnetic pulse tests as a fast-rising current injection source. PMID:26521006

  6. Note: A rectangular pulse generator for 50 kV voltage, 0.8 ns rise time, and 10 ns pulse width based on polymer-film switch

    NASA Astrophysics Data System (ADS)

    Wu, Hanyu; Zhang, Xinjun; Sun, Tieping; Zeng, Zhengzhong; Cong, Peitian; Zhang, Shaoguo

    2015-10-01

    In this article, we describe a rectangular pulse generator, consisting of a polymer-film switch, a tri-plate transmission line, and parallel post-shaped ceramic resistor load, for 50-kV voltage, 0.8-ns rise time, and 10-ns width. The switch and resistors are arranged in atmospheric air and the transmission line can work in atmospheric air or in transformer oil to change the pulse width from 6.7 ns to 10 ns. The fast switching and low-inductance characteristics of the polymer-film switch ensure the fast rising wavefront of <1 ns. This generator can be applied in the calibration of nanosecond voltage dividers and used for electromagnetic pulse tests as a fast-rising current injection source.

  7. Influence of voltage rise time on microwave generation in relativistic backward wave oscillator

    NASA Astrophysics Data System (ADS)

    Wu, Ping; Sun, Jun; Teng, Yan; Deng, Yuqun; Shi, Yanchao; Chen, Changhua

    2015-10-01

    In relativistic backward wave oscillators (RBWOs), although the slow wave structure (SWS) and electron beam determine the main characteristics of beam-wave interaction, many other factors can also significantly affect the microwave generation process. This paper investigates the influence of voltage rise time on beam-wave interaction in RBWOs. Preliminary analysis and PIC simulations demonstrate if the voltage rise time is moderately long, the microwave frequency will gradually increase during the startup process until the voltage reaches its amplitude, which can be explained by the dispersion relation. However, if the voltage rise time is long enough, the longitudinal resonance of the finitely-long SWS will force the RBWO to work with unwanted longitudinal modes for a while and then gradually hop to the wanted longitudinal mode, and this will lead to an impure microwave frequency spectrum. Besides, a longer voltage rise time will delay the startup process and thus lead to a longer microwave saturation time. And if unwanted longitudinal modes are excited due to long voltage rise time, the microwave saturation time will be further lengthened. Therefore, the voltage rise time of accelerators adopted in high power microwave technology should not be too long in case unwanted longitudinal modes are excited.

  8. Influence of voltage rise time on microwave generation in relativistic backward wave oscillator

    SciTech Connect

    Wu, Ping; Deng, Yuqun; Sun, Jun; Teng, Yan; Shi, Yanchao; Chen, Changhua

    2015-10-15

    In relativistic backward wave oscillators (RBWOs), although the slow wave structure (SWS) and electron beam determine the main characteristics of beam-wave interaction, many other factors can also significantly affect the microwave generation process. This paper investigates the influence of voltage rise time on beam-wave interaction in RBWOs. Preliminary analysis and PIC simulations demonstrate if the voltage rise time is moderately long, the microwave frequency will gradually increase during the startup process until the voltage reaches its amplitude, which can be explained by the dispersion relation. However, if the voltage rise time is long enough, the longitudinal resonance of the finitely-long SWS will force the RBWO to work with unwanted longitudinal modes for a while and then gradually hop to the wanted longitudinal mode, and this will lead to an impure microwave frequency spectrum. Besides, a longer voltage rise time will delay the startup process and thus lead to a longer microwave saturation time. And if unwanted longitudinal modes are excited due to long voltage rise time, the microwave saturation time will be further lengthened. Therefore, the voltage rise time of accelerators adopted in high power microwave technology should not be too long in case unwanted longitudinal modes are excited.

  9. Note: A timing micro-channel plate detector with backside fast preamplifier

    SciTech Connect

    Wang, Wei; Yu, Deyang Lu, Rongchun; Liu, Junliang; Cai, Xiaohong

    2014-03-15

    A timing micro-channel plate detector with a backside double-channel fast preamplifier was developed to avoid distortion during signal propagation from the anode to the preamplifier. The mechanical and electronic structure is described. The detector including its backside preamplifier is tested by a {sup 241}Am α-source and a rise time of ∼2 ns with an output background noise of 4 mV{sub rms} was achieved.

  10. Reducing preoperative fasting time: A trend based on evidence

    PubMed Central

    de Aguilar-Nascimento, José Eduardo; Dock-Nascimento, Diana Borges

    2010-01-01

    Preoperative fasting is mandatory before anesthesia to reduce the risk of aspiration. However, the prescribed 6-8 h of fasting is usually prolonged to 12-16 h for various reasons. Prolonged fasting triggers a metabolic response that precipitates gluconeogenesis and increases the organic response to trauma. Various randomized trials and meta-analyses have consistently shown that is safe to reduce the preoperative fasting time with a carbohydrate-rich drink up to 2 h before surgery. Benefits related to this shorter preoperative fasting include the reduction of postoperative gastrointestinal discomfort and insulin resistance. New formulas containing amino acids such as glutamine and other peptides are being studied and are promising candidates to be used to reduce preoperative fasting time. PMID:21160851

  11. CONSTRAINING PHYSICAL PROPERTIES OF TYPE IIn SUPERNOVAE THROUGH RISE TIMES AND PEAK LUMINOSITIES

    SciTech Connect

    Moriya, Takashi J.; Maeda, Keiichi

    2014-08-01

    We investigate the diversity in the wind density, supernova ejecta energy, and ejecta mass in Type IIn supernovae based on their rise times and peak luminosities. We show that the wind density and supernova ejecta properties can be estimated independently if both the rise time and peak luminosity are observed. The peak luminosity is mostly determined by the supernova properties and the rise time can be used to estimate the wind density. We find that the ejecta energies of Type IIn supernovae need to vary by factors of 0.2-5 from the average if their ejecta masses are similar. The diversity in the observed rise times indicates that their wind densities vary by factors of 0.2-2 from the average. We show that Type IIn superluminous supernovae should have not only large wind density but also large ejecta energy and/or small ejecta mass to explain their large luminosities and the rise times at the same time. We also note that shock breakout does not necessarily occur in the wind even if it is optically thick, except for the case of superluminous supernovae, and we analyze the observational data both with and without assuming that the shock breakout occurs in the dense wind of Type IIn supernovae.

  12. Rise Time of the Simulated VERITAS 12 m Davies-Cotton Reflector

    SciTech Connect

    White, Richard J.

    2005-02-21

    The Very Energetic Radiation Imaging Telescope Array System (VERITAS) will utilise Imaging Atmospheric Cherenkov Telescopes (IACTs) based on a Davies-Cotton design with f-number f/1.0 to detect cosmic gamma-rays. Unlike a parabolic reflector, light from the Davies-Cotton does not arrive isochronously at the camera. Here the effect of the telescope geometry on signal rise-time is examined. An almost square-pulse arrival time profile with a rise time of 1.7 ns is found analytically and confirmed through simulation.

  13. Transistorized Marx bank pulse circuit provides voltage multiplication with nanosecond rise-time

    NASA Technical Reports Server (NTRS)

    Jung, E. A.; Lewis, R. N.

    1968-01-01

    Base-triggered avalanche transistor circuit used in a Marx bank pulser configuration provides voltage multiplication with nanosecond rise-time. The avalanche-mode transistors replace conventional spark gaps in the Marx bank. The delay time from an input signal to the output signal to the output is typically 6 nanoseconds.

  14. Rise Time. Operational Control Tests for Wastewater Treatment Facilities. Instructor's Manual [and] Student Workbook.

    ERIC Educational Resources Information Center

    Carnegie, John W.

    The rise time test (along with the settleometer procedure) is used to monitor sludge behavior in the secondary clarifier of an activated sludge system. The test monitors the effect of the nitrification/denitrification process and aids the operator in determining optimum clarifier sludge detention time and, to some extent, optimum degree of…

  15. Distinct Effect of Impact Rise Times on Immediate and Early Neuropathology After Brain Injury in Juvenile Rats

    PubMed Central

    Jayakumar, Archana; Pfister, Bryan J.; Santhakumar, Vijayalakshmi

    2015-01-01

    Traumatic brain injury (TBI) can occur from physical trauma from a wide spectrum of insults ranging from explosions to falls. The biomechanics of the trauma can vary in key features, including the rate and magnitude of the insult. Although the effect of peak injury pressure on neurological outcome has been examined in the fluid percussion injury (FPI) model, it is unknown whether differences in rate of rise of the injury waveform modify cellular and physiological changes after TBI. Using a programmable FPI device, we examined juvenile rats subjected to a constant peak pressure at two rates of injury: a standard FPI rate of rise and a faster rate of rise to the same peak pressure. Immediate postinjury assessment identified fewer seizures and relatively brief loss of consciousness after fast-rise injuries than after standard-rise injuries at similar peak pressures. Compared with rats injured at standard rise, fewer silver-stained injured neuronal profiles and degenerating hilar neurons were observed 4-6 hr after fast-rise FPI. However, 1 week postinjury, both fast- and standard-rise FPI resulted in hilar cell loss and enhanced perforant path-evoked granule cell field excitability compared with sham controls. Notably, the extent of neuronal loss and increase in dentate excitability were not different between rats injured at fast and standard rates of rise to peak pressure. Our data indicate that reduced cellular damage and improved immediate neurological outcome after fast rising primary concussive injuries mask the severity of the subsequent cellular and neurophysiological pathology and may be unreliable as a predictor of prognosis. PMID:24799156

  16. Brainstem auditory evoked responses in man. 1: Effect of stimulus rise-fall time and duration

    NASA Technical Reports Server (NTRS)

    Hecox, K.; Squires, N.; Galambos, R.

    1975-01-01

    Short latency (under 10 msec) responses elicited by bursts of white noise were recorded from the scalps of human subjects. Response alterations produced by changes in the noise burst duration (on-time), inter-burst interval (off-time), and onset and offset shapes were analyzed. The latency of the most prominent response component, wave V, was markedly delayed with increases in stimulus rise time but was unaffected by changes in fall time. Increases in stimulus duration, and therefore in loudness, resulted in a systematic increase in latency. This was probably due to response recovery processes, since the effect was eliminated with increases in stimulus off-time. The amplitude of wave V was insensitive to changes in signal rise and fall times, while increasing signal on-time produced smaller amplitude responses only for sufficiently short off-times. It was concluded that wave V of the human auditory brainstem evoked response is solely an onset response.

  17. Measurement of the Rise-Time in a Single Sided Ladder Detector

    SciTech Connect

    Gerber, C.E.; /Fermilab

    1997-11-10

    In this note we report on the measurement of the preamplifier output rise time for a SVXII chip mounted on a D0 single sided ladder. The measurements were performed on the ladder 001-883-L, using the laser test stand of Lab D. The rise time was measured for different values of the response (or bandwidth) of the preamplifier. As a bigger bandwidth results in longer rise times and therefore in less noise, the largest possible bandwidth consistent with the time between bunch crossings should be chosen to operate the detectors. The rise time is defined as the time elapsed between 10% and 90% of the charge is collected. It is also interesting to measure the time for full charge collection and the percentage of charge collected in 132 ns and 396 ns. The results are shown in table 1, for bandwidths between 2 and 63 (binary numbers). The uncertainty on the time measurement is considered to be {approx} 10 ns. Figure 1 schematically defines the four quantities measured: rise time, time of full charge collection, and percentage of charge collected in 132 ns and 396 ns. Figures 2 to 8 are the actual measurements for bandwidths of 2, 4, 8, 12, 24, 32 and 63. Figure 9 is a second measurement for BW=24, used as a consistency check of the system and the time measurement performed on the plots. The data indicate that the single sided ladders can be operated at BW=63 for 396 ns and BW=12 for 132 ns, achieving full charge collection. This will result in smaller noise than originally anticipated.

  18. Extremum seeking-based optimization of high voltage converter modulator rise-time

    SciTech Connect

    Scheinker, Alexander; Bland, Michael; Krstic, Miroslav; Audia, Jeff

    2013-02-01

    We digitally implement an extremum seeking (ES) algorithm, which optimizes the rise time of the output voltage of a high voltage converter modulator (HVCM) at the Los Alamos Neutron Science Center (LANSCE) HVCM test stand by iteratively, simultaneously tuning the first 8 switching edges of each of the three phase drive waveforms (24 variables total). We achieve a 50 μs rise time, which is reduction in half compared to the 100 μs achieved at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. Considering that HVCMs typically operate with an output voltage of 100 kV, with a 60Hz repetition rate, the 50 μs rise time reduction will result in very significant energy savings. The ES algorithm will prove successful, despite the noisy measurements and cost calculations, confirming the theoretical results that the algorithm is not affected by noise whose frequency components are independent of the perturbing frequencies.

  19. Discriminating cosmic muons and X-rays based on rise time using a GEM detector

    NASA Astrophysics Data System (ADS)

    Wu, Hui-Yin; Zhao, Sheng-Ying; Wang, Xiao-Dong; Zhang, Xian-Ming; Qi, Hui-Rong; Zhang, Wei; Wu, Ke-Yan; Hu, Bi-Tao; Zhang, Yi

    2016-08-01

    Gas electron multiplier (GEM) detectors have been used in cosmic muon scattering tomography and neutron imaging over the last decade. In this work, a triple GEM device with an effective readout area of 10 cm × 10 cm is developed, and a method of discriminating between cosmic muons and X-rays based on rise time is tested. The energy resolution of the GEM detector is tested by 55Fe ray source to prove the GEM detector has a good performance. Analysis of the complete signal-cycles allows us to get the rise time and pulse heights. The experiment result indicates that cosmic muons and X-rays can be discriminated with an appropriate rise time threshold. Supported by National Natural Science Foundation of China (11135002, 11275235, 11405077, 11575073)

  20. A fast preamplifier concept for SiPM-based time-of-flight PET detectors

    NASA Astrophysics Data System (ADS)

    Huizenga, J.; Seifert, S.; Schreuder, F.; van Dam, H. T.; Dendooven, P.; Löhner, H.; Vinke, R.; Schaart, D. R.

    2012-12-01

    Silicon photomultipliers (SiPMs) offer high gain and fast response to light, making them interesting for fast timing applications such as time-of-flight (TOF) PET. To fully exploit the potential of these photosensors, dedicated preamplifiers that do not deteriorate the rise time and signal-to-noise ratio are crucial. Challenges include the high sensor capacitance, typically >300 pF for a 3 mm×3 mm SiPM sensor, as well as oscillation issues. Here we present a preamplifier concept based on low noise, high speed transistors, designed for optimum timing performance. The input stage consists of a transimpedance common-base amplifier with a very low input impedance even at high frequencies, which assures a good linearity and avoids that the high detector capacitance affects the amplifier bandwidth. The amplifier has a fast timing output as well as a 'slow' energy output optimized for determining the total charge content of the pulse. The rise time of the amplifier is about 300 ps. The measured coincidence resolving time (CRT) for 511 keV photon pairs using the amplifiers in combination with 3 mm×3 mm SiPMs (Hamamatsu MPPC-S10362-33-050C) coupled to 3 mm×3 mm×5 mm LaBr3:Ce and LYSO:Ce crystals equals 95 ps FWHM and 138 ps FWHM, respectively.

  1. Brainstem auditory evoked responses in man. 1: Effect of stimulus rise-fall time and duration

    NASA Technical Reports Server (NTRS)

    Hecox, K.; Squires, N.; Galambos, R.

    1975-01-01

    Short latency (under 10 msec) evoked responses elicited by bursts of white noise were recorded from the scalp of human subjects. Response alterations produced by changes in the noise burst duration (on-time) inter-burst interval (off-time), and onset and offset shapes are reported and evaluated. The latency of the most prominent response component, wave V, was markedly delayed with increases in stimulus rise-time but was unaffected by changes in fall-time. The amplitude of wave V was insensitive to changes in signal rise-and-fall times, while increasing signal on-time produced smaller amplitude responses only for sufficiently short off-times. It is concluded that wave V of the human auditory brainstem evoked response is solely an onset response.

  2. Prelude to Cycle 23: The Case for a Fast-Rising, Large Amplitude Cycle

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.; Hathaway, David H.; Reichmann, Edwin J.

    1996-01-01

    For the common data-available interval of cycles 12 to 22, we show that annual averages of sunspot number for minimum years (R(min)) and maximum years (R(max)) and of the minimum value of the aa geomagnetic index in the vicinity of sunspot minimum (aa(min)) are consistent with the notion that each has embedded within its respective record a long-term, linear, secular increase. Extrapolating each of these fits to cycle 23, we infer that it will have R(min) = 12.7 +/- 5.7, R(max) = 176.7 +/- 61.8, and aa(min) = 21.0 +/- 5.0 (at the 95-percent level of confidence), suggesting that cycle 23 will have R(min) greater than 7.0, R(max) greater than 114.9, and aa(min) greater than 16.0 (at the 97.5-percent level of confidence). Such values imply that cycle 23 will be larger than average in size and, consequently (by the Waidmeier effect), will be a fast riser. We also infer from the R(max) and aa(min) records the existence of an even- odd cycle effect, one in which the odd-following cycle is numerically larger in value than the even-leading cycle. For cycle 23, the even-odd cycle effect suggests that R(max) greater than 157.6 and aa(min) greater than 19.0, values that were recorded for cycle 22, the even-leading cycle of the current even-odd cycle pair (cycles 22 and 23). For 1995, the annual average of the aa index measured about 22, while for sunspot number, it was about 18. Because aa(min) usually lags R(min) by 1 year (true for 8 of 11 cycles) and 1996 seems destined to be the year of R(min) for cycle 23, it may be that aa(min) will occur in 1997, although it could occur in 1996 in conjunction with R(min) (true for 3 of 11 cycles). Because of this ambiguity in determining aa(min), no formal prediction based on the correlation of R(max) against aa(min), having r = 0.90, or of R(max) against the combined effects of R(min) and aa(min)-the bivariate technique-having r = 0.99, is possible until 1997, at the earliest.

  3. Ultra-Fast Flash Observatory: Fast Response Space Missions for Early Time Phase of Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Park, I. H.; Ahmad, S.; Barrillon, P.; Brandt, S.; Budtz-Jørgensen, C.; Castro-Tirado, A. J.; Chen, P.; Choi, J. N.; Choi, Y. J.; Connell, P.; Dagoret-Campagne, S.; Eyles, C.; Grossan, B.; Huang, M.-H. A. Huang; Jung, A.; Jeong, S.; Kim, J. E.; Kim, M. B.; Kim, S.-W.; Kim, Y. W.; Krasnov, A. S.; Lee, J.; Lim, H.; Linder, E. V.; Liu, T.-C.; Min, K. W.; Na, G. W.; Nam, J. W.; Panasyuk, M. I.; Park, H. W.; Ripa, J.; Reglero, V.; Rodrigo, J. M.; Smoot, G. F.; Svertilov, S.; Vedenkin, N.; Wang, M.-Z.; Yashin, I.

    2013-07-01

    One of the unexplored domains in the study of gamma-ray bursts (GRBs) is the early time phase of the optical light curve. We have proposed Ultra-Fast Flash Observatory (UFFO) to address this question through extraordinary opportunities presented by a series of small space missions. The UFFO is equipped with a fast-response Slewing Mirror Telescope that uses a rapidly moving mirror or mirror array to redirect the optical beam rather than slewing the entire spacecraft or telescope to aim the optical instrument at the GRB position. The UFFO will probe the early optical rise of GRBs with sub-second response, for the first time, opening a completely new frontier in GRB and transient studies. Its fast response measurements of the optical emission of dozens of GRB each year will provide unique probes of the burst mechanism and test the prospect of GRB as a new standard candle, potentially opening up the z > 10 universe. We describe the current limit in early photon measurements, the aspects of early photon physics, our soon-to-be-launched UFFO-pathfinder mission, and our next planned mission, the UFFO-100.

  4. Rise Time Perception in Children with Reading and Combined Reading and Language Difficulties

    ERIC Educational Resources Information Center

    Beattie, Rachel L.; Manis, Franklin R.

    2013-01-01

    Using a non-speech-specific measure of prosody, rise time perception, Goswami and her colleagues have found that individuals with dyslexia perform significantly worse than nonimpaired readers. Studies have also found that children and adults with specific language impairment were impaired on these tasks. Despite the high comorbidity of these…

  5. Rise Time Perception and Detection of Syllable Stress in Adults with Developmental Dyslexia

    ERIC Educational Resources Information Center

    Leong, Victoria; Hamalainen, Jarmo; Soltesz, Fruzsina; Goswami, Usha

    2011-01-01

    Introduction: The perception of syllable stress has not been widely studied in developmental dyslexia, despite strong evidence for auditory rhythmic perceptual difficulties. Here we investigate the hypothesis that perception of sound rise time is related to the perception of syllable stress in adults with developmental dyslexia. Methods: A…

  6. Fast multigrid fluorescent ion chamber with 0.1 ms time response.

    PubMed

    Suzuki, Motohiro; Kawamura, Naomi; Lytle, Farrel W; Ishikawa, Tetsuya

    2002-03-01

    A fast multigrid ion chamber for the detection of fluorescent X-rays has been developed. The structure of 17 grids with close separation was employed to maximize the time response as well as to give sufficient detection efficiency. The measured rise/fall response time to cyclic X-rays was shorter than that of an existing three-grid ion chamber by more than one order of magnitude. A 0.13 ms time response was obtained at the 500 V applied voltage, where the detector can stably operate without any discharge. The available frequency range is as high as 1 kHz with a practical amplitude response. PMID:11872931

  7. Very fast doped LaBr.sub.3 scintillators and time-of-flight PET

    DOEpatents

    Shah, Kanai S.

    2006-10-31

    The present invention concerns very fast scintillator materials capable of resolving the position of an annihilation event within a portion of a human body cross-section. In one embodiment, the scintillator material comprises LaBr.sub.3 doped with cerium. Particular attention is drawn to LaBr.sub.3 doped with a quantity of Ce that is chosen for improving the timing properties, in particular the rise time and resultant timing resolution of the scintillator, and locational capabilities of the scintillator.

  8. Comparison of occlusion break responses and vacuum rise times of phacoemulsification systems

    PubMed Central

    2014-01-01

    Background Occlusion break surge during phacoemulsification cataract surgery can lead to potential surgical complications. The purpose of this study was to quantify occlusion break surge and vacuum rise time of current phacoemulsification systems used in cataract surgery. Methods Occlusion break surge at vacuum pressures between 200 and 600 mmHg was assessed with the Infiniti® Vision System, the WhiteStar Signature® Phacoemulsification System, and the Centurion® Vision System using gravity-fed fluidics. Centurion Active FluidicsTM were also tested at multiple intraoperative pressure target settings. Vacuum rise time was evaluated for Infiniti, WhiteStar Signature, Centurion, and Stellaris® Vision Enhancement systems. Rise time to vacuum limits of 400 and 600 mmHg was assessed at flow rates of 30 and 60 cc/minute. Occlusion break surge was analyzed by 2-way analysis of variance. Results The Centurion system exhibited substantially less occlusion break surge than the other systems tested. Surge area with Centurion Active Fluidics was similar to gravity fluidics at an equivalent bottle height. At all Centurion Active Fluidics intraoperative pressure target settings tested, surge was smaller than with Infiniti and WhiteStar Signature. Infiniti had the fastest vacuum rise time and Stellaris had the slowest. No system tested reached the 600-mmHg vacuum limit. Conclusions In this laboratory study, Centurion had the least occlusion break surge and similar vacuum rise times compared with the other systems tested. Reducing occlusion break surge may increase safety of phacoemulsification cataract surgery. PMID:25074069

  9. Rise and fall time behavior of the gyrotron backward-wave oscillator.

    PubMed

    Pao, K F; Chang, T H; Chen, S H; Chu, K R

    2006-10-01

    The rise and fall time behavior of a pulsed microwave oscillator is a problem of academic interest. It is also of importance to radar and other applications because it can lead to phase and frequency jitters or even lock the entire pulse into an undesired mode. Here we present a study of the rise and fall time behavior in the gyrotron backward-wave oscillator (gyro-BWO). Single-mode simulations reveal that, during the rise and fall portions of the electron beam pulse, oscillation frequencies of the axial modes vary in such a way that their transit angles remain at the respective optimum values. Thus, axial mode competition and mode switching can readily take place in these transient stages. Time-dependent simulations demonstrate that, under both the gradual and instant turn-on conditions, the axial modes compete in a pattern governed by the characteristic asymmetry of the mode profiles. Other aspects of physics interest include the analysis and explanation of a resultant hysteresis effect between the rise and fall portions of the beam pulse. These understandings are expected to provide the basis for achieving a stable gyro-BWO operating at a single mode throughout the entire beam pulse. PMID:17155180

  10. Pulse Rise Time Characterization of a High Pressure Xenon Gamma Detector for use in Resolution Enhancement

    SciTech Connect

    TROYER, G.L.

    2000-08-25

    High pressure xenon ionization chamber detectors are possible alternatives to traditional thallium doped sodium iodide (NaI(Tl)) and hyperpure germanium as gamma spectrometers in certain applications. Xenon detectors incorporating a Frisch grid exhibit energy resolutions comparable to cadmium/zinc/telluride (CZT) (e.g. 2% {at} 662keV) but with far greater sensitive volumes. The Frisch grid reduces the position dependence of the anode pulse risetimes, but it also increases the detector vibration sensitivity, anode capacitance, voltage requirements and mechanical complexity. We have been investigating the possibility of eliminating the grid electrode in high-pressure xenon detectors and preserving the high energy resolution using electronic risetime compensation methods. A two-electrode cylindrical high pressure xenon gamma detector coupled to time-to-amplitude conversion electronics was used to characterize the pulse rise time of deposited gamma photons. Time discrimination was used to characterize the pulse rise time versus photo peak position and resolution. These data were collected to investigate the effect of pulse rise time compensation on resolution and efficiency.

  11. In-flight fast-timing measurements in Sm152

    NASA Astrophysics Data System (ADS)

    Plaisir, C.; Gaudefroy, L.; Méot, V.; Blanc, A.; Daugas, J. M.; Roig, O.; Arnal, N.; Bonnet, T.; Gobet, F.; Hannachi, F.; Tarisien, M.; Versteegen, M.; Roger, T.; Rejmund, M.; Navin, A.; Schmitt, C.; Fremont, G.; Goupil, J.; Pancin, J.; Spitaels, C.; Zielińska, M.

    2014-02-01

    We report on the first application of in-flight fast-timing measurements, a method developed in order to directly measure lifetimes in the picosecond to nanosecond range. As a proof of principle of the method, lifetimes of the states belonging to the ground-state band in Sm152 are measured up to the 81+ state. An excellent agreement with recommended values is found. A slightly improved determination of the spectroscopic quadrupole moment of the 41+ state is also reported. In-flight fast-timing measurements open interesting opportunities for future studies of collective properties in radioactive nuclei.

  12. Effect of air on energy and rise-time spectra measured by proportional gas counter

    SciTech Connect

    Kawano, T.; Tanaka, M.; Isozumi, S.; Isozumi, Y.; Tosaki, M.; Sugiyama, T.

    2015-03-15

    Air exerts a negative effect on radiation detection using a gas counter because oxygen contained in air has a high electron attachment coefficient and can trap electrons from electron-ion pairs created by ionization from incident radiation in counting gas. This reduces radiation counts. The present study examined the influence of air on energy and rise-time spectra measurements using a proportional gas counter. In addition, a decompression procedure method was proposed to reduce the influence of air and its effectiveness was investigated. For the decompression procedure, the counting gas inside the gas counter was decompressed below atmospheric pressure before radiation detection. For the spectrum measurement, methane as well as various methane and air mixtures were used as the counting gas to determine the effect of air on energy and rise-time spectra. Results showed that the decompression procedure was effective for reducing or eliminating the influence of air on spectra measurement using a proportional gas counter. (authors)

  13. Rise time of voltage pulses in NbN superconducting single photon detectors

    NASA Astrophysics Data System (ADS)

    Smirnov, K. V.; Divochiy, A. V.; Vakhtomin, Yu. B.; Sidorova, M. V.; Karpova, U. V.; Morozov, P. V.; Seleznev, V. A.; Zotova, A. N.; Vodolazov, D. Yu.

    2016-08-01

    We have found experimentally that the rise time of voltage pulse in NbN superconducting single photon detectors increases nonlinearly with increasing the length of the detector L. The effect is connected with dependence of resistance of the detector Rn, which appears after photon absorption, on its kinetic inductance Lk and, hence, on the length of the detector. This conclusion is confirmed by our calculations in the framework of two temperature model.

  14. Extremum seeking-based optimization of high voltage converter modulator rise-time

    DOE PAGESBeta

    Scheinker, Alexander; Bland, Michael; Krstic, Miroslav; Audia, Jeff

    2014-01-01

    We digitally implement an extremum seeking (ES) algorithm, which optimizes the rise time of the output voltage of a high voltage converter modulator (HVCM) at the Los Alamos Neutron Science Center (LANSCE) HVCM test stand by iteratively, simultaneously tuning the first 8 switching edges of each of the three phase drive waveforms (24 variables total). We achieve a 50 μs rise time, which is reduction in half compared to the 100 μs achieved at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. Considering that HVCMs typically operate with an output voltage of 100 kV, with a 60Hz repetitionmore » rate, the 50 μs rise time reduction will result in very significant energy savings. The ES algorithm will prove successful, despite the noisy measurements and cost calculations, confirming the theoretical results that the algorithm is not affected by noise whose frequency components are independent of the perturbing frequencies.« less

  15. Investigating Two Different Training Time Frames during Ramadan Fasting

    PubMed Central

    Kordi, Ramin; Abdollahi, Mohammad; Memari, Amir-Hossein; Najafabadi, Mahboubeh Ghayour

    2011-01-01

    Purpose Muslim athletes may continue training and competing while they are fasting. There is a concern about negative effects of fasting on sports performance. This study aimed to investigate the influence of two training time frames on athletes’ body composition and performance during Ramadan fasting. Methods An observational study was conducted and thirty four male volunteer athletes from different sports including volleyball, karate, taekwondo and football were assigned in two groups. The first group included 14 elite athletes who during Ramadan voluntarily participated in training sessions at 1 hour before Iftar (BI) and the second group of 20 elite athletes who during Ramadan participated in training sessions at 3 hours after Iftar (AI). Testing was performed one week before; in the first and fourth weeks of Ramadan and one week after Ramadan. Weights, heights and skinfold thickness were assessed at each time point and body mass index was calculated. Each player was assessed for agility and explosive strength as well. Results The mean weight and body mass index of both groups decreased significantly during Ramadan (P<0.001). Performance variables were not negatively affected by fasting in BI or AI group athletes. Conclusions Weight reduction might come with either BI or AI training schedules in Ramadan. Daytime or evening training did not inversely affect the agility and power performances in a group of elite athletes during Ramadan fasting. PMID:22375240

  16. Effects of lung time constant, gas analyser delay and rise time on measurements of respiratory dead-space.

    PubMed

    Tang, Yongquan; Turner, Martin J; Baker, A Barry

    2005-12-01

    This study evaluated effects of mechanical time constants (tau(m)) of the respiratory system, delays between flow and CO(2) partial pressure (P(CO)(2)) signals and rise time of the CO(2) analyser on dead-space measurements. A computer model simulated low alveolar dead-space, high alveolar dead-space, 0.2 time delays and anatomic and physiological dead-spaces were calculated. The CO(2) analyser was simulated as a critically damped second-order system with 10-90% rise times of 25-400 ms. The error in measured dead-space increases approximately 2.5% per 10 ms signal delay for normal lungs (tau(m) = 1 s), but has low sensitivity (0.58% per 10 ms) to the rise time of the CO(2) analyser. Sensitivity of physiological dead-space, but not anatomic dead-space to delay is decreased in high alveolar dead-space and abnormal V/Q distribution. Shorter tau(m) increase the error sensitivity of both physiological and anatomic dead-spaces to both delay and rise time. P(CO)(2) and flow should be well synchronized, particularly when tau(m) are short, to avoid dead-space errors. PMID:16311457

  17. Fast Supervision: Changing Supervisory Practice in Changing Times.

    ERIC Educational Resources Information Center

    Green, Pam; Usher, Robin

    2003-01-01

    Describes how research training in Australia is shaped by the knowledge economy and emphasis on "fast" supervision that results in timely degree completion. This pressure limits development of subject-specific methods skills, general research skills, and employability skills. Reconfiguration of the research culture may be necessary. (SK)

  18. Picosecond transient absorption rise time for ultrafast tagging of the interaction of ionizing radiation with scintillating crystals in high energy physics experiments

    NASA Astrophysics Data System (ADS)

    Auffray, E.; Buganov, O.; Fedorov, A.; Korjik, M.; Mechinsky, V.; Tikhomirov, A.; Vasil'ev, A.; Lecoq, P.

    2014-07-01

    Here we report the first results of a search of a signature for picosecond time stamps of the interaction between ionizing particles and transparent crystalline media. The induced absorption with sub-picosecond rise time observed in a cerium fluoride scintillation single crystal under UV excitation is directly associated with the ionization of Ce3+ atoms in CeF3 crystals, and the very fast occurrence thereof can be used to generate picosecond-precise time stamps corresponding to the interaction of ionizing particles with the crystal in high energy physics experiments.

  19. Effect of stratification and geometrical spreading on sonic boom rise time

    NASA Technical Reports Server (NTRS)

    Cleveland, Robin O.; Hamilton, Mark F.; Blackstock, David T.

    1994-01-01

    The purpose of our investigation is to determine the effect of unsteadiness (not associated with turbulence) on rise time. The unsteadiness considered here is due to (1) geometrical spreading, (2) stratification, which includes variation in density, temperature, and relative humidity, and (3) N shaped waveform. A very general Burgers equation, which includes all these effects, is the propagation model for our study. The equation is solved by a new computational algorithm in which all the calculations are done in the time domain. The present paper is a progress report in which some of the factors contributing to unsteadiness are studied, namely geometrical spreading and variation in relative humidity. The work of Pierce and Kang, which motivated our study, is first reviewed. We proceed with a discussion of the Burgers equation model and the algorithm for solving the equation. Some comparison tests to establish the validity of the algorithm are presented. The algorithm is then used to determine the distance required for a steady-state shock, on encountering an abrupt change in relative humidity, to reach a new steady state based on the new humidity. It is found that the transition distance for plane shocks of amplitude 70 Pa is about 4 km when the change in relative humidity is 10 percent. Shocks of amplitude 140 Pa require less distance. The effect of spherical and cylindrical spreading is also considered. We demonstrate that a spreading shock wave never reaches steady state and that its rise time will be less than the equivalent steady state shock. Finally we show that an N wave has a slightly shorter rise time than a step shock of the same amplitude.

  20. NASA AVOSS Fast-Time Wake Prediction Models: User's Guide

    NASA Technical Reports Server (NTRS)

    Ahmad, Nash'at N.; VanValkenburg, Randal L.; Pruis, Matthew

    2014-01-01

    The National Aeronautics and Space Administration (NASA) is developing and testing fast-time wake transport and decay models to safely enhance the capacity of the National Airspace System (NAS). The fast-time wake models are empirical algorithms used for real-time predictions of wake transport and decay based on aircraft parameters and ambient weather conditions. The aircraft dependent parameters include the initial vortex descent velocity and the vortex pair separation distance. The atmospheric initial conditions include vertical profiles of temperature or potential temperature, eddy dissipation rate, and crosswind. The current distribution includes the latest versions of the APA (3.4) and the TDP (2.1) models. This User's Guide provides detailed information on the model inputs, file formats, and the model output. An example of a model run and a brief description of the Memphis 1995 Wake Vortex Dataset is also provided.

  1. Subjective response to sonic booms having different shapes, rise times, and durations

    NASA Technical Reports Server (NTRS)

    Mccurdy, David A.

    1994-01-01

    Two laboratory experiments were conducted to quantify the subjective response of people to simulated outdoor sonic booms having different pressure signatures. The specific objectives of the experiments were to compare subjective response to sonic booms when described in terms of 'loudness' and 'annoyance'; to determine the ability of various noise metrics to predict subjective response to sonic booms; to determine the effects on subjective response of rise time, duration, and level; and to compare the subjective response to 'N-wave' sonic boom signatures with the subjective response to 'minimized' sonic boom signatures. The experiments were conducted in a computer-controlled, man-rated sonic boom simulator capable of reproducing user-specified pressure signatures for a wide range of sonic boom parameters. One hundred and fifty sonic booms representing different combinations of two wave shapes, four rise times, seven durations, and three peak overpressures were presented to 36 test subjects in each experiment. The test subjects in the first experiment made judgments of 'loudness' while the test subjects in the second experiment judged 'annoyance.' Subjective response to sonic booms was the same whether expressed in terms of loudness or in terms of annoyance. Analyses of several different noise metrics indicated that A-weighted sound exposure level and Perceived Level were the best predictors of subjective response. Further analyses indicated that, of these two noise metrics, only Perceived Level completely accounted for the effects of wave shape, rise time, and peak overpressure. Neither metric fully accounted for the effect of duration. However, the magnitude of the duration effect was small over the very wide range of durations considered.

  2. Rise time in 20-32 keV impulsive X-radiation

    NASA Technical Reports Server (NTRS)

    Vorpahl, J. A.; Takakura, T.

    1974-01-01

    A new property of the X-ray impulsive component observed in solar flares is discussed, giving attention to the relation between the slope of the electron power spectrum and the rise time in the 20-32 keV X-ray spike. This particular energy range was chosen because it offered the greatest number of impulsive events while being sufficiently high to avoid contamination by soft X radiation. It is found for the thin-target model that the electron spectrum tends to be softer when the acceleration rate is smaller.

  3. Rise time of inverted triangular prism intruder in vibrating granular bed: Experiments and model

    NASA Astrophysics Data System (ADS)

    Nuraini, N.; Adriani, I. K.; Baladram, M. S.; Viridi, S.

    2012-05-01

    Experiment results and a qualitative model of the phenomenon called Brazil nut effect (BNE) with inverted triangular prism are reported in this work. The model is constructed by considering some forces (earth gravitational force, buoyant force, and fluid viscous force) and using Newton's second law of motion. The rise time of BNE T is defined as time needed for the intruder to be on granular surface with all of his parts (no part is still immersed in the granular bed). One side of the triangular base of the intruder l is varied from 1.5 to 5 cm with other two sides are kept in constant values (1 and 3 cm). It has been observed in experiment that l with value 3-4 cm gives the smaller rise time. Plot of T versus l has the form of concave up parabolic curve with minimum lies at l between 3-4 cm. This observation has been confirmed by the proposed model with the same order of magnitude and similar curve trend.

  4. Fast sensors for time-of-flight imaging applications.

    PubMed

    Vallance, Claire; Brouard, Mark; Lauer, Alexandra; Slater, Craig S; Halford, Edward; Winter, Benjamin; King, Simon J; Lee, Jason W L; Pooley, Daniel E; Sedgwick, Iain; Turchetta, Renato; Nomerotski, Andrei; John, Jaya John; Hill, Laura

    2014-01-14

    The development of sensors capable of detecting particles and radiation with both high time and high positional resolution is key to improving our understanding in many areas of science. Example applications of such sensors range from fundamental scattering studies of chemical reaction mechanisms through to imaging mass spectrometry of surfaces, neutron scattering studies aimed at probing the structure of materials, and time-resolved fluorescence measurements to elucidate the structure and function of biomolecules. In addition to improved throughput resulting from parallelisation of data collection - imaging of multiple different fragments in velocity-map imaging studies, for example - fast image sensors also offer a number of fundamentally new capabilities in areas such as coincidence detection. In this Perspective, we review recent developments in fast image sensor technology, provide examples of their implementation in a range of different experimental contexts, and discuss potential future developments and applications. PMID:24002354

  5. Directional Detection of Fast Neutrons Using a Time Projection Chamber

    SciTech Connect

    Bowden, N; Heffner, M; Carosi, G; Carter, D; Foxe, M; Jovanovic, I

    2009-06-03

    Spontaneous fission in Special Nuclear Material (SNM) such as plutonium and highly enriched uranium (HEU) results in the emission of neutrons with energies in the MeV range (hereafter 'fast neutrons'). These fast neutrons are largely unaffected by the few centimeters of intervening high-Z material that would suffice for attenuating most emitted gamma rays, while tens of centimeters of hydrogenous materials are required to achieve substantial attenuation of neutron fluxes from SNM. Neutron detectors are therefore an important complement to gamma-ray detectors in SNM search and monitoring applications. The rate at which SNM emits fast neutrons varies from about 2 per kilogram per second for typical HEU to some 60,000 per kilogram per second for metallic weapons grade plutonium. These rates can be compared with typical sea-level (cosmogenic) neutron backgrounds of roughly 5 per second per square meter per steradian in the relevant energy range [1]. The fact that the backgrounds are largely isotropic makes directional neutron detection especially attractive for SNM detection. The ability to detect, localize, and ultimately identify fast neutron sources at standoff will ultimately be limited by this background rate. Fast neutrons are particularly well suited to standoff detection and localization of SNM or other fast neutrons sources. Fast neutrons have attenuation lengths of about 60 meters in air, and retain considerable information about their source direction even after one or two scatters. Knowledge of the incoming direction of a fast neutron, from SNM or otherwise, has the potential to significantly improve signal to background in a variety of applications, since the background arriving from any one direction is a small fraction of the total background. Imaging or directional information therefore allows for source detection at a larger standoff distance or with shorter dwell times compared to nondirectional detectors, provided high detection efficiency can be

  6. Attractors of relaxation discrete-time systems with chaotic dynamics on a fast time scale

    NASA Astrophysics Data System (ADS)

    Maslennikov, Oleg V.; Nekorkin, Vladimir I.

    2016-07-01

    In this work, a new type of relaxation systems is considered. Their prominent feature is that they comprise two distinct epochs, one is slow regular motion and another is fast chaotic motion. Unlike traditionally studied slow-fast systems that have smooth manifolds of slow motions in the phase space and fast trajectories between them, in this new type one observes, apart the same geometric objects, areas of transient chaos. Alternating periods of slow regular motions and fast chaotic ones as well as transitions between them result in a specific chaotic attractor with chaos on a fast time scale. We formulate basic properties of such attractors in the framework of discrete-time systems and consider several examples. Finally, we provide an important application of such systems, the neuronal electrical activity in the form of chaotic spike-burst oscillations.

  7. Fast computation of recurrences in long time series

    NASA Astrophysics Data System (ADS)

    Rawald, Tobias; Sips, Mike; Marwan, Norbert; Dransch, Doris

    2014-05-01

    The quadratic time complexity of calculating basic RQA measures, doubling the size of the input time series leads to a quadrupling in operations, impairs the fast computation of RQA in many application scenarios. As an example, we analyze the Potsdamer Reihe, an ongoing non-interrupted hourly temperature profile since 1893, consisting of 1,043,112 data points. Using an optimized single-threaded CPU implementation this analysis requires about six hours. Our approach conducts RQA for the Potsdamer Reihe in five minutes. We automatically split a long time series into smaller chunks (Divide) and distribute the computation of RQA measures across multiple GPU devices. To guarantee valid RQA results, we employ carryover buffers that allow sharing information between pairs of chunks (Recombine). We demonstrate the capabilities of our Divide and Recombine approach to process long time series by comparing the runtime of our implementation to existing RQA tools. We support a variety of platforms by employing the computing framework OpenCL. Our current implementation supports the computation of standard RQA measures (recurrence rate, determinism, laminarity, ratio, average diagonal line length, trapping time, longest diagonal line, longest vertical line, divergence, entropy, trend) and also calculates recurrence times. To utilize the potential of our approach for a number of applications, we plan to release our implementation under an Open Source software license. It will be available at http://www.gfz-potsdam.de/fast-rqa/. Since our approach allows to compute RQA measures for a long time series fast, we plan to extend our implementation to support multi-scale RQA.

  8. Rise time and response measurements on a LiSOCl2 cell

    NASA Technical Reports Server (NTRS)

    Bastien, Caroline; Lecomte, Eric J.

    1992-01-01

    Dynamic impedance tests were performed on a 180 Ah LiSOCl2 cell in the frame of a short term work contract awarded by Aerospatiale as part of the Hermes Space Plane development work. These tests consisted of rise time and response measurements. The rise time test was performed to show the ability to deliver 4 KW, in the nominal voltage range (75-115 V), within less than 100 microseconds, and after a period at rest of 13 days. The response measurements test consisted of step response and frequency response tests. The frequency response test was performed to characterize the response of the LiSOCl2 cell to a positive or negative load step of 10 A starting from various currents. The test was performed for various depths of discharge and various temperatures. The test results were used to build a mathematical, electrical model of the LiSOCl2 cell which are also presented. The test description, test results, electrical modelization description, and conclusions are presented.

  9. Evolution of the solar radius during the solar cycle 24 rise time

    NASA Astrophysics Data System (ADS)

    Meftah, Mustapha

    2015-08-01

    One of the real motivations to observe the solar radius is the suspicion that it might be variable. Possible temporal variations of the solar radius are important as an indicator of internal energy storage and as a mechanism for changes in the total solar irradiance. Measurements of the solar radius are of great interest within the scope of the debate on the role of the Sun in climate change. Solar energy input dominates the surface processes (climate, ocean circulation, wind, etc.) of the Earth. Thus, it appears important to know on what time scales the solar radius and other fundamental solar parameters, like the total solar irradiance, vary in order to better understand and assess the origin and mechanisms of the terrestrial climate changes. The current solar cycle is probably going to be the weakest in 100 years, which is an unprecedented opportunity for studying the variability of the solar radius during this period. This paper presents more than four years of solar radius measurements obtained with a satellite and a ground-based observatory during the solar cycle 24 rise time. Our measurements show the benefit of simultaneous measurements obtained from ground and space observatories. Space observations are a priori most favourable, however, space entails also technical challenges, a harsh environment, and a finite mission lifetime. The evolution of the solar radius during the rising phase of the solar cycle 24 show small variations that are out of phase with solar activity.

  10. A CMOS integrated timing discriminator circuit for fast scintillation counters

    SciTech Connect

    Jochmann, M.W.

    1998-06-01

    Based on a zero-crossing discriminator using a CR differentiation network for pulse shaping, a new CMOS integrated timing discriminator circuit is proposed for fast (t{sub r} {ge} 2 ns) scintillation counters at the cooler synchrotron COSY-Juelich. By eliminating the input signal`s amplitude information by means of an analog continuous-time divider, a normalized pulse shape at the zero-crossing point is gained over a wide dynamic input amplitude range. In combination with an arming comparator and a monostable multivibrator this yields in a highly precise timing discriminator circuit, that is expected to be useful in different time measurement applications. First measurement results of a CMOS integrated logarithmic amplifier, which is part of the analog continuous-time divider, agree well with the corresponding simulations. Moreover, SPICE simulations of the integrated discriminator circuit promise a time walk well below 200 ps (FWHM) over a 40 dB input amplitude dynamic range.

  11. Fluorescence Rise Time Measurements for High Temperature Fluorescence-Based Thermometry

    SciTech Connect

    Allison, S.W.

    2005-03-24

    Certain ceramic-like phosphor materials exhibit bright fluorescence with a pronounced temperature dependence over a range which spans the cryogenic to 1700 C, depending on the specific phosphor. To measure temperature, a surface, for instance a turbine blade, is coated with the material. An optical system, sometimes including optical fibers, conveys stimulating light and collects the emission for analysis. Either emission intensity or decay time may indicate temperature. Previously fielded tests have involved surfaces such as blades, vanes, pistons, in-take valves, sheets of galvanneal steel, etc. The fluorescent coatings may be applied to small parts via sputtering methods or to large areas by mixture with inorganic binders. Presented here are results characterizing fluorescence rise times as a means of determining temperature from ambient to 700 C for Y{sub 2}O{sub 3}:Eu.

  12. Generation of high-voltage pulses with subnanosecond front rise times in open discharge

    SciTech Connect

    Bokhan, P. A.; Gugin, P. P.; Lavrukhin, M. A.; Zakrevsky, Dm. E.

    2013-03-15

    The investigation results for plasma switching devices of high-voltage pulses with pulse rise times less than 1 ns are presented. The approach is based on using conditions suitable for bringing a gas discharge chamber in a state with high conductivity due to generation of an electron beam owing to photoelectron emission from the device cathode. It is shown that in co-axial geometry pulses, switching time 0.45 ns on an active load R{sub L} = 50 {Omega} at voltage U = 20 kV can be achieved. It is shown with the method of doubled impulses that such a device can regenerate the acceptable electric strength during 10 {mu}s. It is indicated of the principle possibility of working in the pulse-periodical regime to the repetition rate of 100 kHz.

  13. Moon Rise

    NASA Video Gallery

    Aboard the International Space Station in May 2012, Expedition 31 astronaut Don Pettit opened the shutters covering the cupola observation windows in time to watch the moon rise. The time-lapse sce...

  14. Fast timing and trigger Cherenkov detector for collider experiments

    NASA Astrophysics Data System (ADS)

    Grigoryev, V. A.; Kaplin, V. A.; Karavicheva, T. L.; Konevskikh, A. S.; Kurepin, A. B.; Loginov, V. A.; Melikyan, Yu A.; Morozov, I. V.; Reshetin, A. I.; Serebryakov, D. V.; Shabanov, A. I.; Slupecki, M.; Trzaska, W. H.; Tykmanov, E. M.

    2016-02-01

    Analysis of fast timing and trigger Cherenkov detector's design for its use in collider experiments is presented. Several specific requirements are taken into account - necessity of the radiator's placement as close to the beam pipe as possible along with the requirement of gapless (solid) radiator's design. Characteristics of the Cherenkov detector's laboratory prototype obtained using a pion beam at the CERN Proton Synchrotron are also presented, showing the possibility of obtaining sufficiently high geometrical efficiency along with good enough time resolution (50 ps sigma).

  15. The Rise Time of Type Ia Supernovae from the Supernova Legacy Survey

    NASA Astrophysics Data System (ADS)

    Conley, A.; Howell, D. A.; Howes, A.; Sullivan, M.; Astier, P.; Balam, D.; Basa, S.; Carlberg, R. G.; Fouchez, D.; Guy, J.; Hook, I.; Neill, J. D.; Pain, R.; Perrett, K.; Pritchet, C. J.; Regnault, N.; Rich, J.; Taillet, R.; Aubourg, E.; Bronder, J.; Ellis, R. S.; Fabbro, S.; Filiol, M.; Le Borgne, D.; Palanque-Delabrouille, N.; Perlmutter, S.; Ripoche, P.

    2006-10-01

    We compare the rise times of nearby and distant Type Ia supernovae (SNe Ia) as a test for evolution using 73 high-redshift spectroscopically confirmed SNe Ia from the first 2 years of the 5 year Supernova Legacy Survey (SNLS) and published observations of nearby SNe. Because of the ``rolling'' search nature of the SNLS, our measurement is approximately 6 times more precise than previous studies, allowing for a more sensitive test of evolution between nearby and distant SNe. Adopting a simple t2 early-time model (as in previous studies), we find that the rest-frame B rise times for a fiducial SN Ia at high and low redshift are consistent, with values 19.10+0.18-0.17(stat)+/-0.2(syst) and 19.58+0.22-0.19 days, respectively; the statistical significance of this difference is only 1.4 σ. The errors represent the uncertainty in the mean rather than any variation between individual SNe. We also compare subsets of our high-redshift data set based on decline rate, host galaxy star formation rate, and redshift, finding no substantive evidence for any subsample dependence. Based on observations obtained with MegaPrime/MegaCam, a joint project of the Canada-France-Hawaii Telescope (CFHT) and CEA/DAPNIA, at CFHT, which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at the Canadian Astronomy Data Centre as part of the CFHT Legacy Survey, a collaborative project of NRC and CNRS.

  16. Anode initiated impulse breakdown in water: the dependence on pulse rise time for nanosecond and sub-nanosecond pulses and initiation mechanism based on electrostriction

    NASA Astrophysics Data System (ADS)

    Seepersad, Yohan; Fridman, Alexander; Dobrynin, Danil

    2015-10-01

    The effect of the voltage rise time on nanosecond and sub-nanosecond impulse breakdown of distilled water is studied. The dependence of anode initiated streamer inception on this parameter is shown to be more intricate than previously reported, particularly as it relates to mechanisms directly in the liquid phase. Dynamics of the emission phase for sub-nanosecond pulses with 600 ps rise time are presented to enable comparison with previous work on nanosecond initiation features. Schlieren imaging is also used to show the development of optical density perturbations and rarefactions as a result of electrostriction in the liquid which were previously found for nanosecond pulses as well. The mechanism of nanopore generation in the liquid due to fast impulses proposed by Shneider, Pekker and Fridman is used to explain the results.

  17. Fast fall-time ion beam in neutron generators

    SciTech Connect

    Ji, Q.; Kwan, J.; Regis, M.; Wu, Y.; Wilde, S.B.; Wallig, J.

    2008-08-10

    Ion beam with a fast fall time is useful in building neutron generators for the application of detecting hidden, gamma-shielded SNM using differential die-away (DDA) technique. Typically a fall time of less than 1 {micro}s can't be achieved by just turning off the power to the ion source due to the slow decay of plasma density (partly determined by the fall time of the RF power in the circuit). In this paper, we discuss the method of using an array of mini-apertures (instead of one large aperture beam) such that gating the beamlets can be done with low voltage and a small gap. This geometry minimizes the problem of voltage breakdown as well as reducing the time of flight to produce fast gating. We have designed and fabricated an array of 16 apertures (4 x 4) for a beam extraction experiment. Using a gating voltage of 1400 V and a gap distance of 1 mm, the fall time of extracted ion beam pulses is less than 1 {micro}s at various beam energies ranging between 400 eV to 800 eV. Usually merging an array of beamlets suffers the loss of beam brightness, i.e., emittance growth, but that is not an important issue for neutron source applications.

  18. Temporal features of spectral integration in the inferior colliculus: effects of stimulus duration and rise time.

    PubMed

    Gans, Donald; Sheykholeslami, Kianoush; Peterson, Diana Coomes; Wenstrup, Jeffrey

    2009-07-01

    This report examines temporal features of facilitation and suppression that underlie spectrally integrative responses to complex vocal signals. Auditory responses were recorded from 160 neurons in the inferior colliculus (IC) of awake mustached bats. Sixty-two neurons showed combination-sensitive facilitation: responses to best frequency (BF) signals were facilitated by well-timed signals at least an octave lower in frequency, in the range 16-31 kHz. Temporal features and strength of facilitation were generally unaffected by changes in duration of facilitating signals from 4 to 31 ms. Changes in stimulus rise time from 0.5 to 5.0 ms had little effect on facilitatory strength. These results suggest that low frequency facilitating inputs to high BF neurons have phasic-on temporal patterns and are responsive to stimulus rise times over the tested range. We also recorded from 98 neurons showing low-frequency (11-32 kHz) suppression of higher BF responses. Effects of changing duration were related to the frequency of suppressive signals. Signals<23 kHz usually evoked suppression sustained throughout signal duration. This and other features of such suppression are consistent with a cochlear origin that results in masking of responses to higher, near-BF signal frequencies. Signals in the 23- to 30-kHz range-frequencies in the first sonar harmonic-generally evoked phasic suppression of BF responses. This may result from neural inhibitory interactions within and below IC. In many neurons, we observed two or more forms of the spectral interactions described here. Thus IC neurons display temporally and spectrally complex responses to sound that result from multiple spectral interactions at different levels of the ascending auditory pathway. PMID:19403742

  19. Distinguishing Between Electrons and γ-Rays in Experiment TGV Using a Pulse Rise Time

    NASA Astrophysics Data System (ADS)

    Čermák, P.; Štekl, I.; Beneš, P.; Brudanin, V. B.; Rukhadze, N. I.; Egorov, V. G.; Kovalenko, V. E.; Kovalík, A.; Pismenniy, R.; Salamatin, A. V.; Timkin, V.; Vylov, Ts.; Vénos, D.

    2002-04-01

    The TGV (Telescope Germanium Vertical) collaboration is interested in the measurement of double-beta decay of 48Ca (TGV I) and 106Cd (TGV II). The background in the experiment TGV I has been suppressed by several methods. One of them was based on distinguishing between electrons and -rays due to the different rise time of the signals obtained from semiconductor detector. Two experimental setups have been tested, the first one used a charge-sensitive analog-to-digital converter, while the second one utilized digital oscilloscope. The reduction of the background counting rate (due to -rays) in single HPGe detector by a factor of (1.4-3.8) was reached.

  20. Breakdown in Atmospheric Pressure Plasma Jets: Nearby Grounds and Voltage Rise Time

    NASA Astrophysics Data System (ADS)

    Lietz, Amanda; Kushner, Mark J.

    2015-09-01

    Atmospheric pressure plasma jets (APPJs) are being investigated to stimulate therapeutic responses in biological systems. These responses are not always consistent. One source of variability may be the design of the APPJs - the number and placement of electrodes, pulse power format - which affects the production of reactive species. In this study, the consequences of design parameters of an APPJ were computationally investigated using nonPDPSIM, a 2 d model. The configuration is a cylindrical tube with one or two ring exterior electrodes, with or without a center pin electrode. The APPJ operates in He/O2 flowing into humid air. We found that the placement of the electrical ground on and around the system is important to the breakdown characteristics of the APPJ, and the electron density and temperature of the resulting plasma. With a single powered ring electrode, the placement of the nearest ground may vary depending on the setup, and this significantly affects the discharge. With two-ring electrodes, the nearest ground plane is well defined, however more distant ground planes can also influence the discharge. With an ionization wave (IW) that propagates out of the tube and into the plume in tens of ns, the rise time of the voltage waveform can be on the same timescale, and so variations in the voltage rise time could produce different IW properties. The effect of ground placement and voltage waveform on IW formation (ns timescales) and production of reactive neutrals (ms timescales) will be discussed. Work supported by DOE (DE-SC0001319) and NSF (CHE-1124724). Done...processed 598 records...15:12:56

  1. A hybrid model for simulation of secondary electron emission in plasma immersion ion implantation under different pulse rise time

    SciTech Connect

    Navab Safa, N. Ghomi, H.

    2015-02-15

    A hybrid fluid Particle in Cell–Monte Carlo Collision (PiC–MCC) model is presented to study the effect of secondary electron emission on the plasma immersion ion implantation process under different pulse rise time. The model describes the temporal evolution of various parameters of plasma such as ion density, ion velocity, secondary electron density, and secondary electron current for different rise times. A 3D–3 V PiC–MCC model is developed to simulate the secondary electrons which are emitted from the sample surface while the plasma ions and electrons are treated using a 1D fluid model. The simulation results indicate that the secondary electron density and secondary electron current increase as the rise time decreases. The main differences between the results for different rise times are found during the initial phase of the pulse. The results are explained through studying the fundamental parameters of plasma.

  2. Brownian motion at fast time scales and thermal noise imaging

    NASA Astrophysics Data System (ADS)

    Huang, Rongxin

    This dissertation presents experimental studies on Brownian motion at fast time scales, as well as our recent developments in Thermal Noise Imaging which uses thermal motions of microscopic particles for spatial imaging. As thermal motions become increasingly important in the studies of soft condensed matters, the study of Brownian motion is not only of fundamental scientific interest but also has practical applications. Optical tweezers with a fast position-sensitive detector provide high spatial and temporal resolution to study Brownian motion at fast time scales. A novel high bandwidth detector was developed with a temporal resolution of 30 ns and a spatial resolution of 1 A. With this high bandwidth detector, Brownian motion of a single particle confined in an optical trap was observed at the time scale of the ballistic regime. The hydrodynamic memory effect was fully studied with polystyrene particles of different sizes. We found that the mean square displacements of different sized polystyrene particles collapse into one master curve which is determined by the characteristic time scale of the fluid inertia effect. The particle's inertia effect was shown for particles of the same size but different densities. For the first time the velocity autocorrelation function for a single particle was shown. We found excellent agreement between our experiments and the hydrodynamic theories that take into account the fluid inertia effect. Brownian motion of a colloidal particle can be used to probe three-dimensional nano structures. This so-called thermal noise imaging (TNI) has been very successful in imaging polymer networks with a resolution of 10 nm. However, TNI is not efficient at micrometer scale scanning since a great portion of image acquisition time is wasted on large vacant volume within polymer networks. Therefore, we invented a method to improve the efficiency of large scale scanning by combining traditional point-to-point scanning to explore large vacant

  3. Time-resolved and time-integrated radiography of fast reactor fuel elements

    SciTech Connect

    De Volpi, A.

    1981-01-01

    The fast-reactor safety program has some unusual requirements in radiography. Applications may be divided into two areas: time-resolved or time-integrated radiography. The fast-neutron hodoscope has supplied all recent time-resolved cineradiographic in-pile fuel-motion data, and various x-ray and photographic techniques have been used for out-of-pile experiments. Thick containers and the large number of radioactive fuel pins involved in safety research have been responsible for some nonconventional applications of time-integrated radiography of stationary objects. Hodoscopes record fuel-motion during transient experiments at the TREAT reactor in the United States and CABRI in France. Other special techniques have been under development for out-of-pile nondestructive radiography of fuel element subassemblies, including fast-neutron and gamma-ray tomographic methods.

  4. Rapid rise time pulsed magnetic field circuit for pump-probe field effect studies.

    PubMed

    Salaoru, T A; Woodward, Jonathan R

    2007-03-01

    Here we describe an electronic circuit capable of producing rapidly switched dc magnetic fields of up to 20 mT with a rise time of 10 ns and a pulse length variable from 50 ns to more than 10 micros, suitable for use in the study of magnetic field effects on radical pair (RP) reactions. This corresponds to switching the field on a time scale short relative to the lifetime of typical RPs and maintaining it well beyond their lifetimes. Previous experiments have involved discharging a capacitor through a low inductance coil for a limited time using a switching circuit. These suffer from decaying field strength over the duration of the pulse given primarily by the ratio of the pulse width to the RC constant of the circuit. We describe here a simple yet elegant solution that completely eliminates this difficulty by employing a feedback loop. This allows a constant field to be maintained over the entire length of the pulse. PMID:17411229

  5. Low Power, High Voltage Power Supply with Fast Rise/Fall Time

    NASA Technical Reports Server (NTRS)

    Bearden, Douglas B. (Inventor)

    2007-01-01

    A low power, high voltage power supply system includes a high voltage power supply stage and a preregulator for programming the power supply stage so as to produce an output voltage which is a predetermined fraction of a desired voltage level. The power supply stage includes a high voltage, voltage doubler stage connected to receive the output voltage from the preregulator and for, when activated, providing amplification of the output voltage to the desired voltage level. A first feedback loop is connected between the output of the preregulator and an input of the preregulator while a second feedback loop is connected between the output of the power supply stage and the input of the preregulator.

  6. Laser pumping of thyristors for fast high current rise-times

    DOEpatents

    Glidden, Steven C.; Sanders, Howard D.

    2013-06-11

    An optically triggered semiconductor switch includes an anode metallization layer; a cathode metallization layer; a semiconductor between the anode metallization layer and the cathode metallization layer and a photon source. The semiconductor includes at least four layers of alternating doping in the form P-N-P-N, in which an outer layer adjacent to the anode metallization layer forms an anode and an outer layer adjacent the cathode metallization layer forms a cathode and in which the anode metallization layer has a window pattern of optically transparent material exposing the anode layer to light. The photon source emits light having a wavelength, with the light from the photon source being configured to match the window pattern of the anode metallization layer.

  7. Low power, high voltage power supply with fast rise/fall time

    NASA Technical Reports Server (NTRS)

    Bearden, Douglas B. (Inventor)

    2007-01-01

    A low power, high voltage power supply system includes a high voltage power supply stage and a preregulator for programming the power supply stage so as to produce an output voltage which is a predetermined fraction of a desired voltage level. The power supply stage includes a high voltage, voltage doubler stage connected to receive the output voltage from the preregulator and for, when activated, providing amplification of the output voltage to the desired voltage level. A first feedback loop is connected between the output of the preregulator and an input of the preregulator while a second feedback loop is connected between the output of the power supply stage and the input of the preregulator.

  8. Fast time variations of supernova neutrino fluxes and their detectability

    SciTech Connect

    Lund, Tina; Marek, Andreas; Janka, Hans-Thomas; Lunardini, Cecilia; Raffelt, Georg

    2010-09-15

    In the delayed explosion scenario of core-collapse supernovae, the accretion phase shows pronounced convective overturns and a low-multipole hydrodynamic instability, the standing accretion shock instability. These effects imprint detectable fast time variations on the emerging neutrino flux. Among existing detectors, IceCube is best suited to this task, providing an event rate of {approx}1000 ms{sup -1} during the accretion phase for a fiducial SN distance of 10 kpc, comparable to what could be achieved with a megaton water Cherenkov detector. If the standing accretion shock instability activity lasts for several hundred ms, a Fourier component with an amplitude of 1% of the average signal clearly sticks out from the shot noise. We analyze in detail the output of axially symmetric hydrodynamical simulations that predict much larger amplitudes up to frequencies of a few hundred Hz. If these models are roughly representative for realistic SNe, fast time variations of the neutrino signal are easily detectable in IceCube or future megaton-class instruments. We also discuss the information that could be deduced from such a measurement about the physics in the SN core and the explosion mechanism of the SN.

  9. A next generation Ultra-Fast Flash Observatory (UFFO-100) for IR/optical observations of the rise phase of gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Grossan, B.; Park, I. H.; Ahmad, S.; Ahn, K. B.; Barrillon, P.; Brandt, S.; Budtz-Jørgensen, C.; Castro-Tirado, A. J.; Chen, P.; Choi, H. S.; Choi, Y. J.; Connell, P.; Dagoret-Campagne, S.; De La Taille, C.; Eyles, C.; Hermann, I.; Huang, M.-H. A.; Jung, A.; Jeong, S.; Kim, J. E.; Kim, M.; Kim, S.-W.; Kim, Y. W.; Lee, J.; Lim, H.; Linder, E. V.; Liu, T.-C.; Lund, N.; Min, K. W.; Na, G. W.; Nam, J. W.; Panasyuk, M. I.; Ripa, J.; Reglero, V.; Rodrigo, J. M.; Smoot, G. F.; Suh, J. E.; Svertilov, S.; Vedenkin, N.; Wang, M.-Z.; Yashin, I.; Zhao, M. H.

    2012-09-01

    The Swift Gamma-ray Burst (GRB) observatory responds to GRB triggers with optical observations in ~ 100 s, butcannot respond faster than ~ 60 s. While some rapid-response ground-based telescopes have responded quickly, thenumber of sub-60 s detections remains small. In 2013 June, the Ultra-Fast Flash Observatory-Pathfinder is expected tobe launched on the Lomonosov spacecraft to investigate early optical GRB emission. Though possessing uniquecapability for optical rapid-response, this pathfinder mission is necessarily limited in sensitivity and event rate; here wediscuss the next generation of rapid-response space observatory instruments. We list science topics motivating ourinstruments, those that require rapid optical-IR GRB response, including: A survey of GRB rise shapes/times,measurements of optical bulk Lorentz factors, investigation of magnetic dominated (vs. non-magnetic) jet models,internal vs. external shock origin of prompt optical emission, the use of GRBs for cosmology, and dust evaporation inthe GRB environment. We also address the impacts of the characteristics of GRB observing on our instrument andobservatory design. We describe our instrument designs and choices for a next generation space observatory as a secondinstrument on a low-earth orbit spacecraft, with a 120 kg instrument mass budget. Restricted to relatively modest mass,power, and launch resources, we find that a coded mask X-ray camera with 1024 cm2 of detector area could rapidlylocate about 64 GRB triggers/year. Responding to the locations from the X-ray camera, a 30 cm aperture telescope witha beam-steering system for rapid (~ 1 s) response and a near-IR camera should detect ~ 29 GRB, given Swift GRBproperties. The additional optical camera would permit the measurement of a broadband optical-IR slope, allowingbetter characterization of the emission, and dynamic measurement of dust extinction at the source, for the first time.

  10. Waiting time at a fast-track diagnostic clinic.

    PubMed

    Basta, Y L; Tytgat, K M A J; Klinkenbijl, J H G; Fockens, P; Smets, E M A

    2016-06-13

    Purpose - Guidelines stating maximum waiting times fail to take cancer patients' expectations into account. Therefore, the purpose of this paper is to assess patients' expectations and experiences with their waiting time at a fast-track clinic. Design/methodology/approach - Patients were selected using a purposeful sampling strategy and were interviewed four times: before the visit; one day after; two weeks after the visit; and one week after starting treatment. Interviews were audiotaped and independently coded by two researchers. Findings - All patients (n=9) preferred a short waiting time before the first visit; they feared that their disease would spread and believed that cancer warrants priority treatment. Six patients experienced the waiting time as short, one had no expectations and two felt they waited longer than expected; three patients changed this evaluation during the study. Six patients received treatment - four preferred to wait before treatment and two wanted to start treatment immediately. Reasons to wait included putting one's affairs in order, or needing to adjust to the diagnosis. Practical implications - Cancer patients prefer a short waiting time before the first visit but have different expectations and needs regarding waiting time before treatment. Ideally, their expectations are managed by their treating physician to match waiting time reality. Originality/value - This is the first study to assess cancer patients' waiting time experiences and how these experiences change over time. This study paves the way for establishing a framework to better assess patient satisfaction with oncology care waiting time. An important aspect, is managing patients' expectations. PMID:27256775

  11. Controllable high voltage source having fast settling time

    NASA Technical Reports Server (NTRS)

    Doong, H.; Acuna, M. H. (Inventor)

    1975-01-01

    A high voltage dc stepping power supply for sampling a utilization device such as an electrostatic analyzer has a relatively fast settling time for voltage steps. The supply includes a waveform generator for deriving a low voltage staircase waveform that feeds a relatively long response time power supply, deriving a high output voltage generally equal to a predetermined multiple of the input voltage. In the power supply, an ac voltage modulated by the staircase waveform is applied to a step-up transformer and then to a voltage multiplier stack to form a high voltage, relatively poor replica of the input waveform at an intermediate output terminal. A constant dc source, applied to the input of the power supply, biases the voltage at the intermediate output terminal to be in excess of the predetermined multiple of the input voltage.

  12. Fast Nonparametric Clustering of Structured Time-Series.

    PubMed

    Hensman, James; Rattray, Magnus; Lawrence, Neil D

    2015-02-01

    In this publication, we combine two Bayesian nonparametric models: the Gaussian Process (GP) and the Dirichlet Process (DP). Our innovation in the GP model is to introduce a variation on the GP prior which enables us to model structured time-series data, i.e., data containing groups where we wish to model inter- and intra-group variability. Our innovation in the DP model is an implementation of a new fast collapsed variational inference procedure which enables us to optimize our variational approximation significantly faster than standard VB approaches. In a biological time series application we show how our model better captures salient features of the data, leading to better consistency with existing biological classifications, while the associated inference algorithm provides a significant speed-up over EM-based variational inference. PMID:26353249

  13. Measurement of intrinsic rise times for various L(Y)SO and LuAG scintillators with a general study of prompt photons to achieve 10 ps in TOF-PET.

    PubMed

    Gundacker, Stefan; Auffray, Etiennette; Pauwels, Kristof; Lecoq, Paul

    2016-04-01

    The coincidence time resolution (CTR) of scintillator based detectors commonly used in positron emission tomography is well known to be dependent on the scintillation decay time (τd) and the number of photons detected (n'), i.e. CTR proportional variant √τd/n'. However, it is still an open question to what extent the scintillation rise time (τr) and other fast or prompt photons, e.g. Cherenkov photons, at the beginning of the scintillation process influence the CTR. This paper presents measurements of the scintillation emission rate for different LSO type crystals, i.e. LSO:Ce, LYSO:Ce, LSO:Ce codoped Ca and LGSO:Ce. For the various LSO-type samples measured we find an average value of 70 ps for the scintillation rise time, although some crystals like LSO:Ce codoped Ca seem to have a much faster rise time in the order of 20 ps. Additional measurements for LuAG:Ce and LuAG:Pr show a rise time of 535 ps and 251 ps, respectively. For these crystals, prompt photons (Cherenkov) can be observed at the beginning of the scintillation event. Furthermore a significantly lower rise time value is observed when codoping with calcium. To quantitatively investigate the influence of the rise time to the time resolution we measured the CTR with the same L(Y)SO samples and compared the values to Monte Carlo simulations. Using the measured relative light yields, rise- and decay times of the scintillators we are able to quantitatively understand the measured CTRs in our simulations. Although the rise time is important to fully explain the CTR variation for the different samples tested we determined its influence on the CTR to be in the order of a few percent only. This result is surprising because, if only photonstatistics of the scintillation process is considered, the CTR would be proportional to the square root of the rise time. The unexpected small rise time influence on the CTR can be explained by the convolution of the scintillation rate with the single photon time

  14. Measurement of intrinsic rise times for various L(Y)SO and LuAG scintillators with a general study of prompt photons to achieve 10 ps in TOF-PET

    NASA Astrophysics Data System (ADS)

    Gundacker, Stefan; Auffray, Etiennette; Pauwels, Kristof; Lecoq, Paul

    2016-04-01

    The coincidence time resolution (CTR) of scintillator based detectors commonly used in positron emission tomography is well known to be dependent on the scintillation decay time ({τd} ) and the number of photons detected ({{n}\\prime} ), i.e. CTR\\propto \\sqrt{{τd}/{{n}\\prime}} . However, it is still an open question to what extent the scintillation rise time ({τr} ) and other fast or prompt photons, e.g. Cherenkov photons, at the beginning of the scintillation process influence the CTR. This paper presents measurements of the scintillation emission rate for different LSO type crystals, i.e. LSO:Ce, LYSO:Ce, LSO:Ce codoped Ca and LGSO:Ce. For the various LSO-type samples measured we find an average value of 70 ps for the scintillation rise time, although some crystals like LSO:Ce codoped Ca seem to have a much faster rise time in the order of 20 ps. Additional measurements for LuAG:Ce and LuAG:Pr show a rise time of 535 ps and 251 ps, respectively. For these crystals, prompt photons (Cherenkov) can be observed at the beginning of the scintillation event. Furthermore a significantly lower rise time value is observed when codoping with calcium. To quantitatively investigate the influence of the rise time to the time resolution we measured the CTR with the same L(Y)SO samples and compared the values to Monte Carlo simulations. Using the measured relative light yields, rise- and decay times of the scintillators we are able to quantitatively understand the measured CTRs in our simulations. Although the rise time is important to fully explain the CTR variation for the different samples tested we determined its influence on the CTR to be in the order of a few percent only. This result is surprising because, if only photonstatistics of the scintillation process is considered, the CTR would be proportional to the square root of the rise time. The unexpected small rise time influence on the CTR can be explained by the convolution of the scintillation rate with the

  15. Experimental control of a fast chaotic time-delay opto-electronic device

    NASA Astrophysics Data System (ADS)

    Blakely, Jonathan Neal

    2003-10-01

    The focus of this thesis is the experimental investigation of the dynamics and control of a new type of fast chaotic opto-electronic device: an active interferometer with electronic bandpass filtered delayed feedback displaying chaotic oscillations with a fundamental frequency as high as 100 MHz. To stabilize the system, I introduce a new form of delayed feedback control suitable for fast time-delay systems. The method provides a new tool for the fundamental study of fast dynamical systems as well as for technological exploitation of chaos. The new opto-electronic device consists of a semiconductor laser, a Mach-Zehnder interferometer, and an electronic feedback loop. The device offers a high degree of design flexibility at a much lower cost than other known sources of fast optical chaos. Both the nonlinearity and the timescale of the oscillations are easily manipulated experimentally. To characterize the dynamics of the system, I observe experimentally its behavior in the time and frequency domains as the feedback-loop gain is varied. The system displays a route to chaos that begins with a Hopf bifurcation from a steady state to a periodic oscillation at the so-called fundamental frequency. Further bifurcations give rise to a chaotic regime with a broad, flattened power spectrum. I develop a mathematical model of the device that shows very good agreement with the observed dynamics. To control chaos in the device, I introduce a new control method suitable for fast time-delay systems, in particular. The method is a modification of a well known control approach called time-delay autosynchronization (TDAS) in which the control perturbation is formed by comparing the current value of a system variable to its value at a time in the past equal to the period of the orbit to be stabilized. The current state of a time-delay dynamical system retains a memory of the state of the system one feedback delay time in the past. As a result, the past state of the system can be used

  16. Fast-track for fast times: catching and keeping generation Y in the nursing workforce.

    PubMed

    Walker, Kim

    2007-04-01

    There is little doubt we find ourselves in challenging times as never before has there been such generational diversity in the nursing workforce. Currently, nurses from four distinct (and now well recognised and discussed) generational groups jostle for primacy of recognition and reward. Equally significant is the acute realisation that our ageing profession must find ways to sustain itself in the wake of huge attrition as the 'baby boomer' nurses start retiring over the next ten to fifteen years. These realities impel us to become ever more strategic in our thinking about how best to manage the workforce of the future. This paper presents two exciting and original innovations currently in train at one of Australia's leading Catholic health care providers: firstly, a new fast-track bachelor of nursing program for fee-paying domestic students. This is a collaborative venture between St Vincent's and Mater Health, Sydney (SV&MHS) and the University of Tasmania (UTas); as far as we know, it is unprecedented in Australia. As well, the two private facilities of SV&MHS, St Vincent's Private (SVPH) and the Mater Hospitals, have developed and implemented a unique 'accelerated progression pathway' (APP) to enable registered nurses with talent and ambition to fast track their career through a competency and merit based system of performance management and reward. Both these initiatives are aimed squarely at the gen Y demographic and provide potential to significantly augment our capacity to recruit and retain quality people well into the future. PMID:17563323

  17. Timed Rise from Floor as a Predictor of Disease Progression in Duchenne Muscular Dystrophy: An Observational Study

    PubMed Central

    Mazzone, Elena S.; Coratti, Giorgia; Sormani, Maria Pia; Messina, Sonia; Pane, Marika; D'Amico, Adele; Colia, Giulia; Fanelli, Lavinia; Berardinelli, Angela; Gardani, Alice; Lanzillotta, Valentina; D’Ambrosio, Paola; Petillo, Roberta; Cavallaro, Filippo; Frosini, Silvia; Bello, Luca; Bonfiglio, Serena; De Sanctis, Roberto; Rolle, Enrica; Forcina, Nicola; Magri, Francesca; Vita, Gianluca; Palermo, Concetta; Donati, Maria Alice; Procopio, Elena; Arnoldi, Maria Teresa; Baranello, Giovanni; Mongini, Tiziana; Pini, Antonella; Battini, Roberta; Pegoraro, Elena; Torrente, Yvan; Previtali, Stefano C.; Bruno, Claudio; Politano, Luisa; Comi, Giacomo P.; D’Angelo, Maria Grazia; Bertini, Enrico; Mercuri, Eugenio

    2016-01-01

    Background The role of timed items, and more specifically, of the time to rise from the floor, has been reported as an early prognostic factor for disease progression and loss of ambulation. The aim of our study was to investigate the possible effect of the time to rise from the floor test on the changes observed on the 6MWT over 12 months in a cohort of ambulant Duchenne boys. Subjects and methods A total of 487 12-month data points were collected from 215 ambulant Duchenne boys. The age ranged between 5.0 and 20.0 years (mean 8.48 ±2.48 DS). Results The results of the time to rise from the floor at baseline ranged from 1.2 to 29.4 seconds in the boys who could perform the test. 49 patients were unable to perform the test at baseline and 87 at 12 month The 6MWT values ranged from 82 to 567 meters at baseline. 3 patients lost the ability to perform the 6mwt at 12 months. The correlation between time to rise from the floor and 6MWT at baseline was high (r = 0.6, p<0.01). Conclusions Both time to rise from the floor and baseline 6MWT were relevant for predicting 6MWT changes in the group above the age of 7 years, with no interaction between the two measures, as the impact of time to rise from the floor on 6MWT change was similar in the patients below and above 350 m. Our results suggest that, time to rise from the floor can be considered an additional important prognostic factor of 12 month changes on the 6MWT and, more generally, of disease progression. PMID:26982196

  18. Distinguishing Fast and Slow Processes in Accuracy - Response Time Data.

    PubMed

    Coomans, Frederik; Hofman, Abe; Brinkhuis, Matthieu; van der Maas, Han L J; Maris, Gunter

    2016-01-01

    We investigate the relation between speed and accuracy within problem solving in its simplest non-trivial form. We consider tests with only two items and code the item responses in two binary variables: one indicating the response accuracy, and one indicating the response speed. Despite being a very basic setup, it enables us to study item pairs stemming from a broad range of domains such as basic arithmetic, first language learning, intelligence-related problems, and chess, with large numbers of observations for every pair of problems under consideration. We carry out a survey over a large number of such item pairs and compare three types of psychometric accuracy-response time models present in the literature: two 'one-process' models, the first of which models accuracy and response time as conditionally independent and the second of which models accuracy and response time as conditionally dependent, and a 'two-process' model which models accuracy contingent on response time. We find that the data clearly violates the restrictions imposed by both one-process models and requires additional complexity which is parsimoniously provided by the two-process model. We supplement our survey with an analysis of the erroneous responses for an example item pair and demonstrate that there are very significant differences between the types of errors in fast and slow responses. PMID:27167518

  19. Distinguishing Fast and Slow Processes in Accuracy - Response Time Data

    PubMed Central

    Coomans, Frederik; Hofman, Abe; Brinkhuis, Matthieu; van der Maas, Han L. J.; Maris, Gunter

    2016-01-01

    We investigate the relation between speed and accuracy within problem solving in its simplest non-trivial form. We consider tests with only two items and code the item responses in two binary variables: one indicating the response accuracy, and one indicating the response speed. Despite being a very basic setup, it enables us to study item pairs stemming from a broad range of domains such as basic arithmetic, first language learning, intelligence-related problems, and chess, with large numbers of observations for every pair of problems under consideration. We carry out a survey over a large number of such item pairs and compare three types of psychometric accuracy-response time models present in the literature: two ‘one-process’ models, the first of which models accuracy and response time as conditionally independent and the second of which models accuracy and response time as conditionally dependent, and a ‘two-process’ model which models accuracy contingent on response time. We find that the data clearly violates the restrictions imposed by both one-process models and requires additional complexity which is parsimoniously provided by the two-process model. We supplement our survey with an analysis of the erroneous responses for an example item pair and demonstrate that there are very significant differences between the types of errors in fast and slow responses. PMID:27167518

  20. Fast Context Switching in Real-Time Propositional Reasoning

    NASA Technical Reports Server (NTRS)

    Nayak, P. Pandurang; Williams, Brian C.

    1997-01-01

    The trend to increasingly capable and affordable control processors has generated an explosion of embedded real-time gadgets that serve almost every function imaginable. The daunting task of programming these gadgets is greatly alleviated with real-time deductive engines that perform all execution and monitoring functions from a single core model, Fast response times are achieved using an incremental propositional deductive database (an LTMS). Ideally the cost of an LTMS's incremental update should be linear in the number of labels that change between successive contexts. Unfortunately an LTMS can expend a significant percentage of its time working on labels that remain constant between contexts. This is caused by the LTMS's conservative approach: a context switch first removes all consequences of deleted clauses, whether or not those consequences hold in the new context. This paper presents a more aggressive incremental TMS, called the ITMS, that avoids processing a significant number of these consequences that are unchanged. Our empirical evaluation for spacecraft control shows that the overhead of processing unchanged consequences can be reduced by a factor of seven.

  1. Diversity of Decline-Rate-Corrected Type 1a Supernova Rise times:One Mode or Two?

    SciTech Connect

    Strovink, Mark

    2007-05-01

    B-band light-curve rise times for eight unusually well-observed nearby Type Ia supernova (SNe) are fitted by a newly developed template-building algorithm, using light-curve functions that are smooth, flexible, and free of potential bias from externally derived templates and other prior assumptions. From the available literature, photometric BVRI data collected over many months, including the earliest points, are reconciled, combined, and fitted to a unique time of explosion for each SN. On average, after they are corrected for light-curve decline rate, three SNe rise in 18.81 {+-} 0.36 days, while five SNe rise in 16.64 {+-} 0.21 days. If all eight SNe are sampled from a single parent population (a hypothesis not favored by statistical tests), the rms intrinsic scatter of the decline-rate-corrected SN rise time is 0.96{sub -0.25}{sup +0.52} days--a first measurement of this dispersion. The corresponding global mean rise time is 17.44 {+-} 0.39 days, where the uncertainty is dominated by intrinsic variance. This value is {approx}2 days shorter than two published averages that nominally are twice as precise, though also based on small samples. When comparing high-z to low-z SN luminosities for determining cosmological parameters, bias can be introduced by use of a light-curve template with an unrealistic rise time. If the period over which light curves are sampled depends on z in a manner typical of current search and measurement strategies, a two-day discrepancy in template rise time can bias the luminosity comparison by {approx}0.03 magnitudes.

  2. Fast-Response-Time Shape-Memory-Effect Foam Actuators

    NASA Technical Reports Server (NTRS)

    Jardine, Peter

    2010-01-01

    Bulk shape memory alloys, such as Nitinol or CuAlZn, display strong recovery forces undergoing a phase transformation after being strained in their martensitic state. These recovery forces are used for actuation. As the phase transformation is thermally driven, the response time of the actuation can be slow, as the heat must be passively inserted or removed from the alloy. Shape memory alloy TiNi torque tubes have been investigated for at least 20 years and have demonstrated high actuation forces [3,000 in.-lb (approximately equal to 340 N-m) torques] and are very lightweight. However, they are not easy to attach to existing structures. Adhesives will fail in shear at low-torque loads and the TiNi is not weldable, so that mechanical crimp fits have been generally used. These are not reliable, especially in vibratory environments. The TiNi is also slow to heat up, as it can only be heated indirectly using heater and cooling must be done passively. This has restricted their use to on-off actuators where cycle times of approximately one minute is acceptable. Self-propagating high-temperature synthesis (SHS) has been used in the past to make porous TiNi metal foams. Shape Change Technologies has been able to train SHS derived TiNi to exhibit the shape memory effect. As it is an open-celled material, fast response times were observed when the material was heated using hot and cold fluids. A methodology was developed to make the open-celled porous TiNi foams as a tube with integrated hexagonal ends, which then becomes a torsional actuator with fast response times. Under processing developed independently, researchers were able to verify torques of 84 in.-lb (approximately equal to 9.5 Nm) using an actuator weighing 1.3 oz (approximately equal to 37 g) with very fast (less than 1/16th of a second) initial response times when hot and cold fluids were used to facilitate heat transfer. Integrated structural connections were added as part of the net shape process, eliminating

  3. FTSPlot: Fast Time Series Visualization for Large Datasets

    PubMed Central

    Riss, Michael

    2014-01-01

    The analysis of electrophysiological recordings often involves visual inspection of time series data to locate specific experiment epochs, mask artifacts, and verify the results of signal processing steps, such as filtering or spike detection. Long-term experiments with continuous data acquisition generate large amounts of data. Rapid browsing through these massive datasets poses a challenge to conventional data plotting software because the plotting time increases proportionately to the increase in the volume of data. This paper presents FTSPlot, which is a visualization concept for large-scale time series datasets using techniques from the field of high performance computer graphics, such as hierarchic level of detail and out-of-core data handling. In a preprocessing step, time series data, event, and interval annotations are converted into an optimized data format, which then permits fast, interactive visualization. The preprocessing step has a computational complexity of ; the visualization itself can be done with a complexity of and is therefore independent of the amount of data. A demonstration prototype has been implemented and benchmarks show that the technology is capable of displaying large amounts of time series data, event, and interval annotations lag-free with ms. The current 64-bit implementation theoretically supports datasets with up to bytes, on the x86_64 architecture currently up to bytes are supported, and benchmarks have been conducted with bytes/1 TiB or double precision samples. The presented software is freely available and can be included as a Qt GUI component in future software projects, providing a standard visualization method for long-term electrophysiological experiments. PMID:24732865

  4. Bubble masks for time-encoded imaging of fast neutrons.

    SciTech Connect

    Brubaker, Erik; Brennan, James S.; Marleau, Peter; Nowack, Aaron B.; Steele, John; Sweany, Melinda; Throckmorton, Daniel J.

    2013-09-01

    Time-encoded imaging is an approach to directional radiation detection that is being developed at SNL with a focus on fast neutron directional detection. In this technique, a time modulation of a detected neutron signal is induced-typically, a moving mask that attenuates neutrons with a time structure that depends on the source position. An important challenge in time-encoded imaging is to develop high-resolution two-dimensional imaging capabilities; building a mechanically moving high-resolution mask presents challenges both theoretical and technical. We have investigated an alternative to mechanical masks that replaces the solid mask with a liquid such as mineral oil. Instead of fixed blocks of solid material that move in pre-defined patterns, the oil is contained in tubing structures, and carefully introduced air gaps-bubbles-propagate through the tubing, generating moving patterns of oil mask elements and air apertures. Compared to current moving-mask techniques, the bubble mask is simple, since mechanical motion is replaced by gravity-driven bubble propagation; it is flexible, since arbitrary bubble patterns can be generated by a software-controlled valve actuator; and it is potentially high performance, since the tubing and bubble size can be tuned for high-resolution imaging requirements. We have built and tested various single-tube mask elements, and will present results on bubble introduction and propagation as a function of tubing size and cross-sectional shape; real-time bubble position tracking; neutron source imaging tests; and reconstruction techniques demonstrated on simple test data as well as a simulated full detector system.

  5. Real-time lucky imaging in FastCam project

    NASA Astrophysics Data System (ADS)

    Rodríguez Ramos, L. F.; Piqueras Meseguer, J. J.; Martin Hernando, Y.; Oscoz, A.; Rebolo, R.

    2008-07-01

    Lucky imaging techniques implemented by the FastCam group (see http://www.iac.es/proyecto/fastcam/) at the Instituto de Astrofisica de Canarias have demonstrated its ability to obtain spectacular diffraction limited images in telescopes ranging from 1 to 4.2 m in visible wavelengths (mainly in the I band), at the expense of using only a small percentage of the available images. This work presents the development of a real-time processor, FPGA-based, capable of performing all the required processing involved in the lucky imaging technique: Bias and flat-field correction, quality evaluation of images, quality threshold for image selection, image recentering and accumulation, and finally sending through Gigabit Ethernet both raw and processed images to a PC computer. Furthermore, a real time display is generated directly from FPGA showing both types of images, plus a histogram of the computed quality values and the threshold used. All processes can co-exist physically located in separated places inside the FPGA, using its natural parallel approach, and can easily handle the 512x512 pixels at 30 fps found at the sensor camera output (an Andor Ixon+ DU-897ECSO EMCCD). Flexibility and parallel processing features of the reconfigurable logic have been used to implement a novel imaging strategy for segmented-mirror telescopes, allowing separate evaluation of every segment and posterior accumulation to achieve the resolution limit of a single segment with the integration capability of the full primary mirror.

  6. Taxi Time Prediction at Charlotte Airport Using Fast-Time Simulation and Machine Learning Techniques

    NASA Technical Reports Server (NTRS)

    Lee, Hanbong

    2016-01-01

    Accurate taxi time prediction is required for enabling efficient runway scheduling that can increase runway throughput and reduce taxi times and fuel consumptions on the airport surface. Currently NASA and American Airlines are jointly developing a decision-support tool called Spot and Runway Departure Advisor (SARDA) that assists airport ramp controllers to make gate pushback decisions and improve the overall efficiency of airport surface traffic. In this presentation, we propose to use Linear Optimized Sequencing (LINOS), a discrete-event fast-time simulation tool, to predict taxi times and provide the estimates to the runway scheduler in real-time airport operations. To assess its prediction accuracy, we also introduce a data-driven analytical method using machine learning techniques. These two taxi time prediction methods are evaluated with actual taxi time data obtained from the SARDA human-in-the-loop (HITL) simulation for Charlotte Douglas International Airport (CLT) using various performance measurement metrics. Based on the taxi time prediction results, we also discuss how the prediction accuracy can be affected by the operational complexity at this airport and how we can improve the fast time simulation model before implementing it with an airport scheduling algorithm in a real-time environment.

  7. EARLY-PHASE PHOTOMETRY AND SPECTROSCOPY OF TRANSITIONAL TYPE Ia SN 2012ht: DIRECT CONSTRAINT ON THE RISE TIME

    SciTech Connect

    Yamanaka, Masayuki; Nogami, Daisaku; Maeda, Keiichi; Kawabata, Miho; Masumoto, Kazunari; Matsumoto, Katsura; Tanaka, Masaomi; Takaki, Katsutoshi; Ueno, Issei; Itoh, Ryosuke; Kawabata, Koji S.; Moritani, Yuki; Akitaya, Hiroshi; Yoshida, Michitoshi; Arai, Akira; Honda, Satoshi; Nishiyama, Koichi; Kabashima, Fujio

    2014-02-20

    We report photometric and spectroscopic observations of the nearby Type Ia Supernova (SN Ia) 2012ht from –15.8 days to +49.1 days after B-band maximum. The decline rate of the light curve is Δm {sub 15}(B) = 1.39 ± 0.05 mag, which is intermediate between normal and subluminous SNe Ia, and similar to that of the ''transitional'' Type Ia SN 2004eo. The spectral line profiles also closely resemble those of SN 2004eo. We were able to observe SN 2012ht at a very early phase, when it was still rising and was about three magnitudes fainter than at the peak. The rise time to the B-band maximum is estimated to be 17.6 ± 0.5 days and the time of the explosion is MJD 56277.98 ± 0.13. SN 2012ht is the first transitional SN Ia whose rise time is directly measured without using light curve templates, and the fifth SN Ia overall. This rise time is consistent with those of the other four SNe within the measurement error, even including the extremely early detection of SN 2013dy. The rising part of the light curve can be fitted by a quadratic function, and shows no sign of a shock-heating component due to the interaction of the ejecta with a companion star. The rise time is significantly longer than that inferred for subluminous SNe such as SN 1991bg, which suggests that a progenitor and/or explosion mechanism of transitional SNe Ia are more similar to normal SNe Ia rather than to subluminous SNe Ia.

  8. Lava Morphology Classification of a Fast-Spreading Ridge Using Deep-Towed Sonar Data: East Pacific Rise

    NASA Astrophysics Data System (ADS)

    Meyer, J.; White, S.

    2005-05-01

    Classification of lava morphology on a regional scale contributes to the understanding of the distribution and extent of lava flows at a mid-ocean ridge. Seafloor classification is essential to understand the regional undersea environment at midocean ridges. In this study, the development of a classification scheme is found to identify and extract textural patterns of different lava morphologies along the East Pacific Rise using DSL-120 side-scan and ARGO camera imagery. Application of an accurate image classification technique to side-scan sonar allows us to expand upon the locally available visual ground reference data to make the first comprehensive regional maps of small-scale lava morphology present at a mid-ocean ridge. The submarine lava morphologies focused upon in this study; sheet flows, lobate flows, and pillow flows; have unique textures. Several algorithms were applied to the sonar backscatter intensity images to produce multiple textural image layers useful in distinguishing the different lava morphologies. The intensity and spatially enhanced images were then combined and applied to a hybrid classification technique. The hybrid classification involves two integrated classifiers, a rule-based expert system classifier and a machine learning classifier. The complementary capabilities of the two integrated classifiers provided a higher accuracy of regional seafloor classification compared to using either classifier alone. Once trained, the hybrid classifier can then be applied to classify neighboring images with relative ease. This classification technique has been used to map the lava morphology distribution and infer spatial variability of lava effusion rates along two segments of the East Pacific Rise, 17 deg S and 9 deg N. Future use of this technique may also be useful for attaining temporal information. Repeated documentation of morphology classification in this dynamic environment can be compared to detect regional seafloor change.

  9. Parallel Configuration For Fast Superconducting Strip Line Detectors With Very Large Area In Time Of Flight Mass Spectrometry

    SciTech Connect

    Casaburi, A.; Zen, N.; Suzuki, K.; Ohkubo, M.; Ejrnaes, M.; Cristiano, R.; Pagano, S.

    2009-12-16

    We realized a very fast and large Superconducting Strip Line Detector based on a parallel configuration of nanowires. The detector with size 200x200 {mu}m{sup 2} recorded a sub-nanosecond pulse width of 700 ps in FWHM (400 ps rise time and 530 ps relaxation time) for lysozyme monomers/multimers molecules accelerated at 175 keV in a Time of Flight Mass Spectrometer. This record is the best in the class of superconducting detectors and comparable with the fastest NbN superconducting single photon detector of 10x10 {mu}m{sup 2}. We succeeded in acquiring mass spectra as the first step for a scale-up to {approx}mm pixel size for high throughput MS analysis, while keeping a fast response.

  10. MOSFET solid state switching circuit improves the 0 to 99% rise time for framing camera deflection electronics

    SciTech Connect

    Rivera, A.T.; Thomas, S.

    1996-09-01

    We have improved the 0 to 99% rise time voltage on our 2 frame deflection plates from 160 to 65 nS with the addition of a peaking circuit that works in conjunction with our primary 2 frame deflection circuitry. Our peaking technique has applications to other HV pulsers including those which must drive 51 ohm loads. Generally, rise time voltages are measured between 10 and 90%. To minimize the camera image blur resulting from the dynamic influence of deflection plate potentials acting on photocathode electrons, it was necessary to design a circuit that would rise from 0 to the 99% voltage level in under 100nS. Once this voltage was reached, it was necessary to stay within 1% of the attained voltage level for a duration of 1 uS. This was accomplished with the use of MOSFET solid state switching.

  11. Lifetime measurements in transitional nuclei by fast electronic scintillation timing

    NASA Astrophysics Data System (ADS)

    Caprio, M. A.; Zamfir, N. V.; Casten, R. F.; Amro, H.; Barton, C. J.; Beausang, C. W.; Cooper, J. R.; Gürdal, G.; Hecht, A. A.; Hutter, C.; Krücken, R.; McCutchan, E. A.; Meyer, D. A.; Novak, J. R.; Pietralla, N.; Ressler, J. J.; Berant, Z.; Brenner, D. S.; Gill, R. L.; Regan, P. H.

    2002-10-01

    A new generation of experiments studying nuclei in spherical-deformed transition regions has been motivated by the introduction of innovative theoretical approaches to the treatment of these nuclei. The important structural signatures in the transition regions, beyond the basic yrast level properties, involve γ-ray transitions between low-spin, non-yrast levels, and so information on γ-ray branching ratios and absolute matrix elements (or level lifetimes) for these transitions is crucial. A fast electronic scintillation timing (FEST) system [H. Mach, R. L. Gill, and M. Moszyński, Nucl. Instrum. Methods A 280, 49 (1989)], making use of BaF2 and plastic scintillation detectors, has been implemented at the Yale Moving Tape Collector for the measurement of lifetimes of states populated in β^ decay. Experiments in the A100 (Pd, Ru) and A150 (Dy, Yb) regions have been carried out, and a few examples will be presented. Supported by the US DOE under grants and contracts DE-FG02-91ER-40609, DE-FG02-88ER-40417, and DE-AC02-98CH10886 and by the German DFG under grant Pi 393/1.

  12. Synchronous timing of multi-energy fast beam extraction during a single AGS cycle

    SciTech Connect

    Gabusi, J.; Naase, S.

    1985-01-01

    Synchronous triggering of fast beams is required because the field of Kicker Magnets must rise within the open space between one beam bunch and the next. Within the Brookhaven AGS, Fast Extracted Beam (FEB) triggering combines nominal timing, based on beam energy with bunch-to-bunch synchronization, based on the accelerating rf waveform. During beam acceleration, a single bunch is extracted at 22 GeV/c and within the same AGS cycle, the remaining eleven bunches are extracted at 28.4 GeV/c. When the single bunch is extracted, a ''hole'', which is left in the remaining circulating beam, can appear in random locations within the second extraction during successive AGS cycles. To overcome this problem, a synchronous rf/12 counting scheme and logic circuitry are used to keep track of the bunch positions relative to each other, and to place the ''hole'' in any desired location within the second extraction. The rf/12 signal is used also to synchronize experimenters triggers.

  13. Study of the time response of a LuAG(Pr) crystal for fast timing applications

    NASA Astrophysics Data System (ADS)

    Fraile, L. M.; Mach, H.; Picado, E.; Vedia, V.; Udías, J. M.

    2013-06-01

    The recently developed praseodymium-doped lutetium aluminum garnet, LuAG(Pr), holds a strong potential for fast timing applications. In this study we report on the time response of LuAG(Pr) at 22Na and 60Co photon energies. The measurements were performed using a small crystal cube of 1 cm3 coupled to a Hamamatsu R5320 photomultiplier tube. The full width at half maximum (FWHM) time resolution is found to be 147±2 ps at 60Co energies, and 238±2 ps at 22Na.

  14. Turbulence Scales, Rise Times, Caustics, and the Simulation of Sonic Boom Propagation

    NASA Technical Reports Server (NTRS)

    Pierce, Allan D.

    1996-01-01

    The general topic of atmospheric turbulence effects on sonic boom propagation is addressed with especial emphasis on taking proper and efficient account of the contributions of the portion oi the turbulence that is associated with extremely high wavenumber components. The recent work reported by Bart Lipkens in his doctoral thesis is reexamined to determine whether the good agreement between his measured rise times with the 1971 theory of the author is fortuitous. It is argued that Lipken's estimate of the distance to the first caustic was a gross overestimate because of the use of a sound speed correlation function shaped like a gaussian curve. In particular, it is argued that the expected distance to the first caustic varies with the kinematic viscosity nu and the energy epsilon dissipated per unit mass per unit time, and the sound speed c as : d(sub first caustic) = nu(exp 7/12) c(exp 2/3)/ epsilon(exp 5/12)(nu x epsilon/c(exp 4))(exp a), where the exponent a is greater than -7/12 and can be argued to be either O or 1/24. In any event, the surprising aspect of the relationship is that it actually goes to zero as the viscosity goes to zero with s held constant. It is argued that the apparent overabundance of caustics can be grossly reduced by a general computational and analytical perspective that partitions the turbulence into two parts, divided by a wavenumber k(sub c). Wavenumbers higher than kc correspond to small-scale turbulence, and the associated turbulence can be taken into account by a renormalization of the ambient sound speed so that the result has a small frequency dependence that results from a spatial averaging over of the smaller-scale turbulent fluctuations. Selection of k(sub c). can be made so large that only a very small number of caustics are encountered if one adopts the premise that the frequency dispersion of pulses is caused by that part of the turbulence spectrum which lies in the inertial range originally predicted by Kolmogoroff. The

  15. Learning Novel Phonological Representations in Developmental Dyslexia: Associations with Basic Auditory Processing of Rise Time and Phonological Awareness

    ERIC Educational Resources Information Center

    Thomson, Jennifer M.; Goswami, Usha

    2010-01-01

    Across languages, children with developmental dyslexia are known to have impaired lexical phonological representations. Here, we explore associations between learning new phonological representations, phonological awareness, and sensitivity to amplitude envelope onsets (rise time). We show that individual differences in learning novel phonological…

  16. Fasting, Circadian Rhythms, and Time-Restricted Feeding in Healthy Lifespan.

    PubMed

    Longo, Valter D; Panda, Satchidananda

    2016-06-14

    Most animals alternate periods of feeding with periods of fasting often coinciding with sleep. Upon >24 hr of fasting, humans, rodents, and other mammals enter alternative metabolic phases, which rely less on glucose and more on ketone body-like carbon sources. Both intermittent and periodic fasting result in benefits ranging from the prevention to the enhanced treatment of diseases. Similarly, time-restricted feeding (TRF), in which food consumption is restricted to certain hours of the day, allows the daily fasting period to last >12 hr, thus imparting pleiotropic benefits. Understanding the mechanistic link between nutrients and the fasting benefits is leading to the identification of fasting-mimicking diets (FMDs) that achieve changes similar to those caused by fasting. Given the pleiotropic and sustained benefits of TRF and FMDs, both basic science and translational research are warranted to develop fasting-associated interventions into feasible, effective, and inexpensive treatments with the potential to improve healthspan. PMID:27304506

  17. Interaction-powered Supernovae: Rise-time versus Peak-luminosity Correlation and the Shock-breakout Velocity

    NASA Astrophysics Data System (ADS)

    Ofek, Eran O.; Arcavi, Iair; Tal, David; Sullivan, Mark; Gal-Yam, Avishay; Kulkarni, Shrinivas R.; Nugent, Peter E.; Ben-Ami, Sagi; Bersier, David; Cao, Yi; Cenko, S. Bradley; De Cia, Annalisa; Filippenko, Alexei V.; Fransson, Claes; Kasliwal, Mansi M.; Laher, Russ; Surace, Jason; Quimby, Robert; Yaron, Ofer

    2014-06-01

    Interaction of supernova (SN) ejecta with the optically thick circumstellar medium (CSM) of a progenitor star can result in a bright, long-lived shock-breakout event. Candidates for such SNe include Type IIn and superluminous SNe. If some of these SNe are powered by interaction, then there should be a specific relation between their peak luminosity, bolometric light-curve rise time, and shock-breakout velocity. Given that the shock velocity during shock breakout is not measured, we expect a correlation, with a significant spread, between the rise time and the peak luminosity of these SNe. Here, we present a sample of 15 SNe IIn for which we have good constraints on their rise time and peak luminosity from observations obtained using the Palomar Transient Factory. We report on a possible correlation between the R-band rise time and peak luminosity of these SNe, with a false-alarm probability of 3%. Assuming that these SNe are powered by interaction, combining these observables and theory allows us to deduce lower limits on the shock-breakout velocity. The lower limits on the shock velocity we find are consistent with what is expected for SNe (i.e., ~104 km s-1). This supports the suggestion that the early-time light curves of SNe IIn are caused by shock breakout in a dense CSM. We note that such a correlation can arise from other physical mechanisms. Performing such a test on other classes of SNe (e.g., superluminous SNe) can be used to rule out the interaction model for a class of events.

  18. Interaction-powered supernovae: rise-time versus peak-luminosity correlation and the shock-breakout velocity

    SciTech Connect

    Ofek, Eran O.; Arcavi, Iair; Tal, David; Gal-Yam, Avishay; Ben-Ami, Sagi; De Cia, Annalisa; Yaron, Ofer; Sullivan, Mark; Kulkarni, Shrinivas R.; Cao, Yi; Nugent, Peter E.; Bersier, David; Cenko, S. Bradley; Filippenko, Alexei V.; Fransson, Claes; Kasliwal, Mansi M.; Laher, Russ; Surace, Jason; Quimby, Robert

    2014-06-20

    Interaction of supernova (SN) ejecta with the optically thick circumstellar medium (CSM) of a progenitor star can result in a bright, long-lived shock-breakout event. Candidates for such SNe include Type IIn and superluminous SNe. If some of these SNe are powered by interaction, then there should be a specific relation between their peak luminosity, bolometric light-curve rise time, and shock-breakout velocity. Given that the shock velocity during shock breakout is not measured, we expect a correlation, with a significant spread, between the rise time and the peak luminosity of these SNe. Here, we present a sample of 15 SNe IIn for which we have good constraints on their rise time and peak luminosity from observations obtained using the Palomar Transient Factory. We report on a possible correlation between the R-band rise time and peak luminosity of these SNe, with a false-alarm probability of 3%. Assuming that these SNe are powered by interaction, combining these observables and theory allows us to deduce lower limits on the shock-breakout velocity. The lower limits on the shock velocity we find are consistent with what is expected for SNe (i.e., ∼10{sup 4} km s{sup –1}). This supports the suggestion that the early-time light curves of SNe IIn are caused by shock breakout in a dense CSM. We note that such a correlation can arise from other physical mechanisms. Performing such a test on other classes of SNe (e.g., superluminous SNe) can be used to rule out the interaction model for a class of events.

  19. Universal relations for solitary waves in granular crystals under shocks with finite rise and decay times

    NASA Astrophysics Data System (ADS)

    Arif Hasan, M.; Nemat-Nasser, Sia

    2016-04-01

    We focus on solitary waves generated in arrays of lightly contacting spherical elastic granules by shock forces of steep rise and slow decay durations and establish a priori: (i) whether the peak value of the resulting solitary wave would be greater than, equal to, or less than the peak value of the input shock force; (ii) the magnitude of the peak value of the solitary waves; (iii) the magnitude of the linear momentum in each solitary wave; (iv) the magnitude of the linear momentum added to the remaining granules if the first granule is ejected; and (v) a quantitative estimate of the effect of the granules' radius, density, and stiffness on force amplification or mitigation. We have supported the analytical results by direct numerical simulations.

  20. Preoperative fasting times in elective surgical patients at a referral Hospital in Botswana

    PubMed Central

    Abebe, Worknehe Agegnehu; Rukewe, Ambrose; Bekele, Negussie Alula; Stoffel, Moeng; Dichabeng, Mompelegi Nicoh; Shifa, Jemal Zeberga

    2016-01-01

    Introduction Adults and children are required to fast before anaesthesia to reduce the risk of regurgitation and aspiration of gastric contents. However, prolonged periods of fasting are unnecessary and may cause complications. This study was conducted to evaluate preoperative fasting period in our centre and compare it with the ASA recommendations and factors that influence fasting periods. Methods This is a cross-sectional study of preoperative fasting times among elective surgical patients. A total numbers of 260 patients were interviewed as they arrived at the reception area of operating theatre using questionnaire. Results Majority of patients (98.1%) were instructed to fast from midnight. Fifteen patients (5.8%) reported that they were told the importance of preoperative fasting. The mean fasting period were 15.9±2.5 h (range 12.0-25.3 h) for solids and 15.3±2.3 h (range 12.0-22.0 h) for liquids. The mean duration of fasting was significantly longer for patients operated after midday compared to those operated before midday, p<0.001. Conclusion The mean fasting periods were 7.65 times longer for clear liquid and 2.5 times for solids than the ASA guidelines. It is imperative that the Hospital should establish Preoperative fasting policies and teach the staff who should ensure compliance with guidelines. PMID:27222691

  1. Actual preoperative fasting time in Brazilian hospitals: the BIGFAST multicenter study

    PubMed Central

    de Aguilar-Nascimento, José E; de Almeida Dias, Ana L; Dock-Nascimento, Diana B; Correia, Maria Isabel TD; Campos, Antonio CL; Portari-Filho, Pedro Eder; Oliveira, Sergio S

    2014-01-01

    Background Prolonged fasting increases organic response to trauma. This multicenter study investigated the gap between the prescribed and the actual preoperative fasting times in Brazilian hospitals and factors associated with this gap. Methods Patients (18–90-years-old) who underwent elective operations between August 2011 and September 2012 were included in the study. The actual and prescribed times for fasting were collected and correlated with sex, age, surgical disease (malignancies or benign disease), operation type, American Society of Anesthesiologists score, type of hospital (public or private), and nutritional status. Results A total of 3,715 patients (58.1% females) with a median age of 49 (18–94) years from 16 Brazilian hospitals entered the study. The median (range) preoperative fasting time was 12 (2–216) hours, and fasting time was longer (P<0.001) in hospitals using a traditional fasting protocol (13 [6–216] hours) than in others that had adopted new guidelines (8 [2–48] hours). Almost 80% (n=2,962) of the patients were operated on after 8 or more hours of fasting and 46.2% (n=1,718) after more than 12 hours. Prolonged fasting was not associated with physical score, age, sex, type of surgery, or type of hospital. Patients operated on due to a benign disease had an extended duration of preoperative fasting. Conclusion Actual preoperative fasting time is significantly longer than prescribed fasting time in Brazilian hospitals. Most of these hospitals still adopt traditional rather than modern fasting guidelines. All patients are at risk of long periods of fasting, especially those in hospitals that follow traditional practices. PMID:24627636

  2. Early to Rise? The Effect of Daily Start Times on Academic Performance

    ERIC Educational Resources Information Center

    Edwards, Finley

    2012-01-01

    Local school districts often stagger daily start times for their schools in order to reduce busing costs. This paper uses data on all middle school students in Wake County, NC from 1999 to 2006 to identify the causal effect of daily start times on academic performance. Using variation in start times within schools over time, the effect is a two…

  3. Crustal thickness from 3D MCS data collected over the fast-spreading East Pacific Rise at 9°50'N

    NASA Astrophysics Data System (ADS)

    Aghaei, O.; Nedimović, M. R.; Canales, J.; Carton, H. D.; Carbotte, S. M.; Mutter, J. C.

    2011-12-01

    We compute, analyze and present crustal thickness variations for a section of the fast-spreading East Pacific Rise (EPR). The area of 3D coverage is between 9°38'N and 9°58' N (~1000 km2), where the documented eruptions of 1990-91 and 2005-06 occurred. The crustal thickness is computed by depth converting the two-way reflection travel times from the seafloor to the Moho. The seafloor and Moho reflections are picked on the migrated stack volume produced from the 3D multichannel seismic (MCS) data collected on R/V Marcus G. Langseth in summer of 2008 during cruise MGL0812. The crustal velocities used for depth conversion were computed by Canales et al. (2003; 2011) by simultaneous inversion of seismic refractions and wide-angle Moho reflection traveltimes from four ridge-parallel and one ridge-perpendicular ocean bottom seismometer (OBS) profile for which data were collected during the 1998 UNDERSHOOT experiment. The MCS data analysis included 1D and 2D filtering, offset-dependent spherical divergence correction, surface-consistent amplitude correction, common midpoint (CMP) sort with flex binning, velocity analysis, normal moveout, and CMP stretch mute. The poststack processing includes seafloor multiple mute and 3D Kirchhoff poststack time migration. Here we use the crustal thickness and Moho seismic signature variations to detail their relationship with ridge segmentation, crustal age, bathymetry, and on- and off-axis magmatism. On the western flank (Pacific plate) from 9°41' to 9°48', the Moho reflection is strong. From 9°48' to 9°52', the Moho reflection varies from moderate to weak and disappears from ~3 km to ~9 km from the ridge axis. On the eastern flank (Cocos plate) from 9°41' to 9°51', the Moho reflection varies from strong to moderate. From 9°51' to 9°54' the Moho reflection varies from moderate to weak and disappears beneath a region ~3 km to ~9 km from the axis. On the Cocos plate, across-axis crustal thickness variations (5.5-6.2 km) show a

  4. A time-gating scintillation detector for the measurement of laser-induced fast neutrons

    SciTech Connect

    Lee, Sungman; Park, Sangsoon; Yea, Kwon-hae; Cha, Hyungki

    2009-06-15

    A time-gating scintillation detector, in which a fast high voltage switch is used for gating a channel photomultiplier, was developed for a measurement of laser-induced fast neutrons. The x rays generated from the intense femtosecond laser and the solid target interactions were suppressed selectively and a time-of-flight signal of a laser-generated fast neutron was measured effectively. The detector was used successfully to measure the neutron yield of a femtosecond, deuterated, polystyrene plasma.

  5. A time-gating scintillation detector for the measurement of laser-induced fast neutrons.

    PubMed

    Lee, Sungman; Park, Sangsoon; Yea, Kwon-hae; Cha, Hyungki

    2009-06-01

    A time-gating scintillation detector, in which a fast high voltage switch is used for gating a channel photomultiplier, was developed for a measurement of laser-induced fast neutrons. The x rays generated from the intense femtosecond laser and the solid target interactions were suppressed selectively and a time-of-flight signal of a laser-generated fast neutron was measured effectively. The detector was used successfully to measure the neutron yield of a femtosecond, deuterated, polystyrene plasma. PMID:19566199

  6. Spark-Timing Control Based on Correlation of Maximum-Economy Spark Timing, Flame-front Travel, and Cylinder-Pressure Rise

    NASA Technical Reports Server (NTRS)

    Cook, Harvey A; Heinicke, Orville H; Haynie, William H

    1947-01-01

    An investigation was conducted on a full-scale air-cooled cylinder in order to establish an effective means of maintaining maximum-economy spark timing with varying engine operating conditions. Variable fuel-air-ratio runs were conducted in which relations were determined between the spark travel, and cylinder-pressure rise. An instrument for controlling spark timing was developed that automatically maintained maximum-economy spark timing with varying engine operating conditions. The instrument also indicated the occurrence of preignition.

  7. Investigation of spatial gusts with extreme rise time on the extreme loads of pitch-regulated wind turbines

    NASA Astrophysics Data System (ADS)

    Bierbooms, Wim

    2005-01-01

    It is assumed that the extreme loading of pitch-regulated turbines is caused by gusts with an extreme rise time rather than an extreme gust amplitude. A special kind of wind field simulation, so-called constrained stochastic simulation, is dealt with in order to generate the desired gusts. Just as in wind field simulation for fatigue purposes, it is assumed that turbulence is Gaussian; a possibility is mentioned of how to deal with non-Gaussian behaviour. On the basis of the presented theory it can be stated that the stochastic gusts produced in this way are, in a statistical sense, not distinguishable from gusts selected from a (very long) time series. An example of a spatial gust as well as the mean spatial gust shape is shown. For a reference turbine the maximum blade root flapping moment has been determined as a function of the gust centre in the rotor plane; the maximum response is obtained in the case where the gust hits one of the rotor blades at 75% of the radius. When the gust duration is large compared with the integral time constant of the controller, the controller can handle the gust as expected. However, even for small rise times it turns out that the maximum flap moment due to the gust is not significantly higher than that due to the background turbulence and 1P excitations. This may indicate that perhaps extreme rise time gusts do not lead to extreme loading of pitch-regulated wind turbines. For a final judgement a proper probabilistic approach is necessary; an outline of such an approach has been sketched. Furthermore, it is recommended to do research on other gust types in order to find out the type which leads to the extreme wind turbine loading. Copyright

  8. Extracting Short Rise-Time Velocity Profiles with Digital Down-Shift Analysis of Optically Up-Converted PDV Data

    SciTech Connect

    Abel Diaz, Nathan Riley, Cenobio Gallegos, Matthew Teel, Michael Berninger, Thomas W. Tunnell

    2010-09-08

    This work describes the digital down-shift (DDS) technique, a new method of extracting short rise-time velocity profiles in the analysis of optically up-converted PDV data. The DDS technique manipulates the PDV data by subtracting a constant velocity (i.e., the DDS velocity νDDS) from the velocity profile. DDS exploits the simple fact that the optically up-converted data ride on top of a base velocity (ν0, the apparent velocity at no motion) with a rapid rise to a high velocity (νf) of a few km/s or more. Consequently, the frequency content of the signal must describe a velocity profile that increases from ν0 to ν0 + νf. The DDS technique produces velocity reversals in the processed data before shock breakout when ν0 < νDDS < ν0 + νf. The DDS analysis process strategically selects specific DDS velocities (velocity at which the user down shifts the data) that produce anomalous reversals (maxima and/or minima), which are predictable and easy to identify in the mid-range of the data. Additional analysis determines when these maxima and minima occur. By successive application of the DDS technique and iterative analysis, velocity profiles are extracted as time as a function of velocity rather than as a function of time as it would be in a conventional velocity profile. Presented results include a description of DDS, velocity profiles extracted from laser-driven shock data with rise times of 200 ps or less, and a comparison with other techniques.

  9. Simple scaling laws for influenza A rise time, duration, and severity.

    PubMed

    Chang, David B; Young, Carl S

    2007-06-21

    Simple scaling laws are developed for the severity and characteristic time scales of influenza A infection in man. The scaling laws are based on a model of the infection described by six coupled ordinary differential equations that describe the time courses of the numbers of infectious viral particles, activated cytotoxic T-lymphocytes, interferon molecules, infected cells, uninfected cells, and the subset of uninfected cells that are protected by interferon from viral infection. Computer simulations show that the disease can be regarded approximately as a two-stage process. In the first stage, the growth in the number of infected cells is determined primarily by the interferon-enhanced limitation in the available number of target cells. In the second stage, the bulk of the duration of the infection is determined mainly by the destruction of the infected cells by the cytotoxic T-lymphocytes. The severity and characteristic times of the infection are found to depend simply on the logarithm of the initial number of viruses. PMID:17379249

  10. Rise-time response of nickel-foil-on-Kapton-substrate, hot-film, shear-stress sensors

    NASA Technical Reports Server (NTRS)

    Reda, Daniel C.

    1991-01-01

    An existing nickel-foil-on-Kapton-substrate sensor design was modified by including two heated elements in an attempt to minimize or reduce substrate conduction effects. The rise-time responses of the original and modified sensors were then investigated in unsteady flows of 0.5-1-s duration, consistent with flows encountered in wind-energy applications. The results obtained indicate a measurable degradation in transient performance due to the activation of the dynamic guard heater. Transient heat conduction within the substrate remains the limiting factor in such applications.

  11. Analog electro-optical readout of SiPMs achieves fast timing required for time-of-flight PET/MR

    PubMed Central

    Bieniosek, MF

    2015-01-01

    The design of combined positron emission tomography/magnetic resonance (PET/MR) systems presents a number of challenges to engineers, as it forces the PET system to acquire data in space constrained environment that is sensitive to electro-magnetic interference and contains high static, radio frequency (RF) and gradient fields. In this work we validate fast timing performance of a PET scintillation detector using a potentially very compact, very low power, and MR compatible readout method in which analog silicon photomultipliers (SiPM) signals are transmitted optically away from the MR bore with little or even no additional readout electronics. This analog ‘electro-optial’ method could reduce the entire PET readout in the MR bore to two compact, low power components (SiPMs and lasers). Our experiments show fast timing performance from analog electro-optical readout with and without pre-amplification. With 3mm × 3mm × 20mm lutetium-yttrium oxyorthosilicate (LYSO) crystals and Excelitas SiPMs the best two-sided fwhm coincident timing resolution achieved was 220 +/- 3ps in electrical mode, 230 +/- 2ps in electro-optical with preamp mode, and 253 +/- 2ps in electro-optical without preamp mode. Timing measurements were also performed with Hamamatsu SiPMs and 3mm × 3mm × 5mm crystals. In the future the timing degradation seen can be further reduced with lower laser noise or improvements SiPM rise time or gain. PMID:25905626

  12. Analog electro-optical readout of SiPMs achieves fast timing required for time-of-flight PET/MR

    NASA Astrophysics Data System (ADS)

    Bieniosek, M. F.; Levin, C. S.

    2015-05-01

    The design of combined positron emission tomography/magnetic resonance (PET/MR) systems presents a number of challenges to engineers, as it forces the PET system to acquire data in a space constrained environment that is sensitive to electro-magnetic interference and contains high static, radio frequency and gradient fields. In this work we validate fast timing performance of a PET scintillation detector using a potentially very compact, very low power, and MR compatible readout method in which analog silicon photomultipliers (SiPM) signals are transmitted optically away from the MR bore with little or even no additional readout electronics. This analog ‘electro-optial’ method could reduce the entire PET readout in the MR bore to two compact, low power components (SiPMs and lasers). Our experiments show fast timing performance from analog electro-optical readout with and without pre-amplification. With 3 mm × 3 mm × 20 mm lutetium-yttrium oxyorthosilicate (LYSO) crystals and Excelitas SiPMs the best two-sided fwhm coincident timing resolution achieved was 220 +/- 3 ps in electrical mode, 230 +/- 2 ps in electro-optical with preamp mode, and 253 +/- 2 ps in electro-optical without preamp mode. Timing measurements were also performed with Hamamatsu SiPMs and 3 mm × 3 mm × 5 mm crystals. In the future the timing degradation seen can be further reduced with lower laser noise or improvements SiPM rise time or gain.

  13. Temperature Rise Induced by Light Curing Unit Can Shorten Enamel Acid-Etching Time

    PubMed Central

    Najafi Abrandabadi, Ahmad; Sheikh-Al-Eslamian, Seyedeh Mahsa; Panahandeh, Narges

    2015-01-01

    Objectives: The aim of this in-vitro study was to assess the thermal effect of light emitting diode (LED) light curing unit on the enamel etching time. Materials and Methods: Three treatment groups with 15 enamel specimens each were used in this study: G1: Fifteen seconds of etching, G2: Five seconds of etching, G3: Five seconds of etching plus LED light irradiation (simultaneously). The micro shear bond strength (μSBS) of composite resin to enamel was measured. Results: The mean μSBS values ± standard deviation were 51.28±2.35, 40.47±2.75 and 50.00±2.59 MPa in groups 1, 2 and 3, respectively. There was a significant difference between groups 1 and 2 (P=0.013) and between groups 2 and 3 (P=0.032) in this respect, while there was no difference between groups 1 and 3 (P=0.932). Conclusion: Simultaneous application of phosphoric acid gel over enamel surface and light irradiation using a LED light curing unit decreased enamel etching time to five seconds without compromising the μSBS. PMID:27559352

  14. A metacalibrated time-tree documents the early rise of flowering plant phylogenetic diversity.

    PubMed

    Magallón, Susana; Gómez-Acevedo, Sandra; Sánchez-Reyes, Luna L; Hernández-Hernández, Tania

    2015-07-01

    The establishment of modern terrestrial life is indissociable from angiosperm evolution. While available molecular clock estimates of angiosperm age range from the Paleozoic to the Late Cretaceous, the fossil record is consistent with angiosperm diversification in the Early Cretaceous. The time-frame of angiosperm evolution is here estimated using a sample representing 87% of families and sequences of five plastid and nuclear markers, implementing penalized likelihood and Bayesian relaxed clocks. A literature-based review of the palaeontological record yielded calibrations for 137 phylogenetic nodes. The angiosperm crown age was bound within a confidence interval calculated with a method that considers the fossil record of the group. An Early Cretaceous crown angiosperm age was estimated with high confidence. Magnoliidae, Monocotyledoneae and Eudicotyledoneae diversified synchronously 135-130 million yr ago (Ma); Pentapetalae is 126-121 Ma; and Rosidae (123-115 Ma) preceded Asteridae (119-110 Ma). Family stem ages are continuously distributed between c. 140 and 20 Ma. This time-frame documents an early phylogenetic proliferation that led to the establishment of major angiosperm lineages, and the origin of over half of extant families, in the Cretaceous. While substantial amounts of angiosperm morphological and functional diversity have deep evolutionary roots, extant species richness was probably acquired later. PMID:25615647

  15. Local time distributions of repetition periods for rising tone lower band chorus waves in the magnetosphere

    NASA Astrophysics Data System (ADS)

    Shue, Jih-Hong; Hsieh, Yi-Kai; Tam, Sunny W. Y.; Wang, Kaiti; Fu, Hui Shan; Bortnik, Jacob; Tao, Xin; Hsieh, Wen-Chieh; Pi, Gilbert

    2015-10-01

    Whistler mode chorus waves generally occur outside the plasmapause in the magnetosphere. The most striking feature of the waves is their occurrence in discrete elements. One of the parameters that describe the discrete elements is the repetition period (Trp), the time between consecutive elements. The Trp has not been studied statistically before. We use high-resolution waveform data to derive distributions of Trp for different local times. We find that the average Trp for the nightside (0.56 s) and dawnside (0.53 s) are smaller than those for the dayside (0.81 s) and duskside (0.97 s). Through a comparison with the background plasma and magnetic fields, we also find that the total magnetic field and temperature are the main controlling factors that affect the variability of Trp. These results are important for understanding the generation mechanism of chorus and choosing parameters in simulations that model the acceleration and loss of electrons by wave-particle interactions.

  16. Achieving fast timing performance with multiplexed SiPMs.

    PubMed

    Bieniosek, M F; Cates, J W; Levin, C S

    2016-04-01

    Using time of flight (ToF) measurements for positron emission tomography (PET) is an attractive avenue for increasing the signal to noise (SNR) ratio of PET images. However, achieving excellent time resolution required for high SNR gain using silicon photomultipliers (SiPM) requires many resource heavy high bandwidth readout channels. A method of multiplexing many SiPM signals into a single electronic channel would greatly simplify ToF PET systems. However, multiplexing SiPMs degrades time resolution because of added dark counts and signal shaping. In this work the relative contribution of dark counts and signal shaping to timing degradation is simulated and a baseline correction technique to mitigate the effect of multiplexing on the time resolution of analog SiPMs is simulated and experimentally verified. A charge sharing network for multiplexing is proposed and tested. Results show a full width at half maximum (FWHM) coincidence time resolution of [Formula: see text] ps for a single 3 mm  ×  3 mm  ×  20 mm LYSO scintillation crystals coupled to an array of sixteen 3 mm  ×  3 mm SiPMs that are multiplexed to a single timing channel (in addition to 4 position channels). A [Formula: see text] array of 3 mm  ×  3 mm  ×  20 mm LFS crystals showed an average FWHM coincidence time resolution of [Formula: see text] ps using the same timing scheme. All experiments were performed at room temperature with no thermal regulation. These results show that excellent time resolution for ToF can be achieved with a highly multiplexed analog SiPM readout. PMID:26987898

  17. Achieving fast timing performance with multiplexed SiPMs

    NASA Astrophysics Data System (ADS)

    Bieniosek, M. F.; Cates, J. W.; Levin, C. S.

    2016-04-01

    Using time of flight (ToF) measurements for positron emission tomography (PET) is an attractive avenue for increasing the signal to noise (SNR) ratio of PET images. However, achieving excellent time resolution required for high SNR gain using silicon photomultipliers (SiPM) requires many resource heavy high bandwidth readout channels. A method of multiplexing many SiPM signals into a single electronic channel would greatly simplify ToF PET systems. However, multiplexing SiPMs degrades time resolution because of added dark counts and signal shaping. In this work the relative contribution of dark counts and signal shaping to timing degradation is simulated and a baseline correction technique to mitigate the effect of multiplexing on the time resolution of analog SiPMs is simulated and experimentally verified. A charge sharing network for multiplexing is proposed and tested. Results show a full width at half maximum (FWHM) coincidence time resolution of 232+/- 2 ps for a single 3 mm  ×  3 mm  ×  20 mm LYSO scintillation crystals coupled to an array of sixteen 3 mm  ×  3 mm SiPMs that are multiplexed to a single timing channel (in addition to 4 position channels). A 4× 4 array of 3 mm  ×  3 mm  ×  20 mm LFS crystals showed an average FWHM coincidence time resolution of 278+/- 7 ps using the same timing scheme. All experiments were performed at room temperature with no thermal regulation. These results show that excellent time resolution for ToF can be achieved with a highly multiplexed analog SiPM readout.

  18. Composition and timing of carbonate vein precipitation within the igneous basement of the Early Cretaceous Shatsky Rise, NW Pacific

    NASA Astrophysics Data System (ADS)

    Geldmacher, J.; Li, S.; Hauff, F. F.; Garbe-Schoenberg, C.; Yu, S.; Zhao, S.; Rausch, S.

    2013-12-01

    Shatsky Rise is an Early Cretaceous large igneous province located in the NW Pacific ca. 1500 km east of Japan and is the third-largest oceanic plateau on Earth (after Ontong Java and Kerguelen). Numerous calcium carbonate veins were recovered from the igneous basement of Shatsky Rise during Integrated Ocean Drilling Program Expedition 324 (Sager et al., 2010). The chemical (Sr/Ca, Mg/Ca) and isotopic (87Sr/86Sr, 143Nd/144Nd, δ18O, δ13C) compositions of these veins were determined to constrain the timing of vein formation and to provide valuable data for the reconstruction of past seawater composition. A dominant control of seawater chemistry on calcite composition is evident for most investigated vein samples with varying compositional contribution from the basaltic basement. The Sr/Ca ratio of the vein calcite is positively correlated with Mg/Ca and with δ18O, indicating warmer/colder precipitation temperatures with decreasing/increasing Sr/Ca (and Mg/Ca) ratios, respectively. Distinctly higher formation temperatures (as inferred from oxygen isotope ratios) indicative of hydrothermal vein formation are only observed at one site (Site U1350, drilled into the central part of Shatsky Rise). The highest 87Sr/86Sr ratios (least basement influence) of vein samples at each drill site range form 0.707264 to 0.707550 and are believed to best reflect contemporaneous Early Cretaceous seawater composition. In principle, age information can be deduced by correlating these ratios with the global seawater Sr isotope evolution. Since the Sr isotopic composition of seawater has fluctuated three times between the early and mid Cretaceous (McArthur et al., 2001) no unambiguous precipitation ages can be constrained by this method and vein precipitation could have occurred at any time between ˜80 and 140 Ma. However, based on combined chemical and isotopic data and correlations of vein composition with formation depth and inferred temperature, we argue for a rather early

  19. TIME EVOLUTION OF PLASMA PARAMETERS DURING THE RISE OF A SOLAR PROMINENCE INSTABILITY

    SciTech Connect

    Orozco Suárez, D.; Asensio Ramos, A.; Trujillo Bueno, J.; Díaz, A. J.

    2014-04-10

    We present high-spatial resolution spectropolarimetric observations of a quiescent hedgerow prominence taken in the He I 1083.0 nm triplet. The observation consisted of a time series in sit-and-stare mode of ∼36 minutes duration. The spectrograph's slit crossed the prominence body and we recorded the time evolution of individual vertical threads. Eventually, we observed the development of a dark Rayleigh-Taylor plume that propagated upward with a velocity, projected onto the plane of the sky, of 17 km s{sup –1}. Interestingly, the plume apex collided with the prominence threads pushing them aside. We inferred Doppler shifts, Doppler widths, and magnetic field strength variations by interpreting the He I Stokes profiles with the HAZEL code. The Doppler shifts show that clusters of threads move coherently while individual threads have oscillatory patterns. Regarding the plume we found strong redshifts (∼9-12 km s{sup –1}) and large Doppler widths (∼10 km s{sup –1}) at the plume apex when it passed through the prominence body and before it disintegrated. We associate the redshifts with perspective effects while the Doppler widths are more likely due to an increase in the local temperature. No local variations of the magnetic field strength associated with the passage of the plume were found; this leads us to conclude that the plumes are no more magnetized than the surroundings. Finally, we found that some of the threads' oscillations are locally damped, what allowed us to apply prominence seismology techniques to infer additional prominence physical parameters.

  20. Geochemistry of Fast-Spreading Lower Oceanic Crust: Results from Drilling at the Hess Deep Rift (ODP Leg 147 and IODP Expedition 345; East Pacific Rise)

    NASA Astrophysics Data System (ADS)

    Godard, M.; Falloon, T.; Gillis, K. M.; Akizawa, N.; de Brito Adriao, A.; Koepke, J.; Marks, N.; Meyer, R.; Saha, A.; Garbe-Schoenberg, C. D.

    2014-12-01

    The Hess Deep Rift, where the Cocos Nazca Ridge propagates into the young, fast-spread East Pacific Rise crust, exposes a dismembered, but nearly complete, lower crustal section. The extensive exposures of the plutonic crust were drilled at 3 sites during ODP Leg 147 (Nov. 1992-Jan. 1993) and IODP Expedition 345 (Dec. 2012-Feb. 2013). We report preliminary results of a bulk rock geochemical study (major and trace elements) carried out on 109 samples representative of the different drilled lithologies. The shallowest gabbroic rocks were sampled at ODP Site 894. They comprise gabbronorite, gabbro, olivine gabbro and gabbronorite. They have evolved compositions with Mg# 39-55, Yb 4-8 x chondrite and Eu/Eu* 1-1.6. Olivine gabbro and troctolite were dominant at IODP Site U1415, with minor gabbro, gabbronorite and clinopyroxene oikocryst-bearing troctolite and gabbro. All U1415 gabbroic rocks have primitive compositions except for one gabbronorite rubble that is similar in composition to the shallow gabbros. Olivine gabbro, gabbro and gabbronorite overlap in composition: they have high Mg# (79-87) and Ni (130-570 ppm), low TiO2 (0.1-0.3 wt.%) and Yb (1.3-2.3 x chondrite) and positive Eu anomaly (Eu/Eu*=1.9-2.7). Troctolite has high Mg# (81-89), Ni (260-1500 ppm) and low TiO2 (<0.1 wt.%) and Yb (~0.5xchondrite) and large Eu/Eu* (>4). ODP Site 895 recovered sequences of highly depleted harzburgite, dunite and troctolite (Yb down to <0.1xchondrite) that are interpreted as a mantle-crust transition zone. Basalts were recovered at Sites 894 and U1415: they have low Yb (0.5-0.9xN6MORB) and are depleted in the most incompatible elements (Ce/Yb=0.6-0.9xN-MORB). The main geochemical characteristics of Site U1415 and 894 gabbroic rocks are consistent with formation as a cumulate sequence from a common parental MORB melt; troctolites are the most primitive end-member of this sequence. They overlap in composition with the most primitive of slow and fast spread crust gabbroic rocks.

  1. Fast underdetermined BSS architecture design methodology for real time applications.

    PubMed

    Mopuri, Suresh; Reddy, P Sreenivasa; Acharyya, Amit; Naik, Ganesh R

    2015-01-01

    In this paper, we propose a high speed architecture design methodology for the Under-determined Blind Source Separation (UBSS) algorithm using our recently proposed high speed Discrete Hilbert Transform (DHT) targeting real time applications. In UBSS algorithm, unlike the typical BSS, the number of sensors are less than the number of the sources, which is of more interest in the real time applications. The DHT architecture has been implemented based on sub matrix multiplication method to compute M point DHT, which uses N point architecture recursively and where M is an integer multiples of N. The DHT architecture and state of the art architecture are coded in VHDL for 16 bit word length and ASIC implementation is carried out using UMC 90 - nm technology @V DD = 1V and @ 1MHZ clock frequency. The proposed architecture implementation and experimental comparison results show that the DHT design is two times faster than state of the art architecture. PMID:26737514

  2. An advanced vision-based system for real-time displacement measurement of high-rise buildings

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Han; Ho, Hoai-Nam; Shinozuka, Masanobu; Lee, Jong-Jae

    2012-12-01

    This paper introduces an advanced vision-based system for dynamic real-time displacement measurement of high-rise buildings using a partitioning approach. The partitioning method is based on the successive estimation of relative displacements and rotational angles at several floors using a multiple vision-based displacement measurement system. In this study, two significant improvements were made to realize the partitioning method: (1) time synchronization, (2) real-time dynamic measurement. Displacement data and time synchronization information are wirelessly transferred via a network using the TCP/IP protocol. The time synchronization process is periodically conducted by the master system to guarantee the system time at the master and slave systems are synchronized. The slave system is capable of dynamic real-time measurement and it is possible to economically expand measurement points at slave levels using commercial devices. To verify the accuracy and feasibility of the synchronized multi-point vision-based system and partitioning approach, many laboratory tests were carried out on a three-story steel frame model. Furthermore, several tests were conducted on a five-story steel frame tower equipped with a hybrid mass damper to experimentally confirm the effectiveness of the proposed system.

  3. A fast, time-accurate unsteady full potential scheme

    NASA Technical Reports Server (NTRS)

    Shankar, V.; Ide, H.; Gorski, J.; Osher, S.

    1985-01-01

    The unsteady form of the full potential equation is solved in conservation form by an implicit method based on approximate factorization. At each time level, internal Newton iterations are performed to achieve time accuracy and computational efficiency. A local time linearization procedure is introduced to provide a good initial guess for the Newton iteration. A novel flux-biasing technique is applied to generate proper forms of the artificial viscosity to treat hyperbolic regions with shocks and sonic lines present. The wake is properly modeled by accounting not only for jumps in phi, but also for jumps in higher derivatives of phi, obtained by imposing the density to be continuous across the wake. The far field is modeled using the Riemann invariants to simulate nonreflecting boundary conditions. The resulting unsteady method performs well which, even at low reduced frequency levels of 0.1 or less, requires fewer than 100 time steps per cycle at transonic Mach numbers. The code is fully vectorized for the CRAY-XMP and the VPS-32 computers.

  4. Fast SIFT design for real-time visual feature extraction.

    PubMed

    Chiu, Liang-Chi; Chang, Tian-Sheuan; Chen, Jiun-Yen; Chang, Nelson Yen-Chung

    2013-08-01

    Visual feature extraction with scale invariant feature transform (SIFT) is widely used for object recognition. However, its real-time implementation suffers from long latency, heavy computation, and high memory storage because of its frame level computation with iterated Gaussian blur operations. Thus, this paper proposes a layer parallel SIFT (LPSIFT) with integral image, and its parallel hardware design with an on-the-fly feature extraction flow for real-time application needs. Compared with the original SIFT algorithm, the proposed approach reduces the computational amount by 90% and memory usage by 95%. The final implementation uses 580-K gate count with 90-nm CMOS technology, and offers 6000 feature points/frame for VGA images at 30 frames/s and ∼ 2000 feature points/frame for 1920 × 1080 images at 30 frames/s at the clock rate of 100 MHz. PMID:23743775

  5. Fast and Flexible Multivariate Time Series Subsequence Search

    NASA Technical Reports Server (NTRS)

    Bhaduri, Kanishka; Oza, Nikunj C.; Zhu, Qiang; Srivastava, Ashok N.

    2010-01-01

    Multivariate Time-Series (MTS) are ubiquitous, and are generated in areas as disparate as sensor recordings in aerospace systems, music and video streams, medical monitoring, and financial systems. Domain experts are often interested in searching for interesting multivariate patterns from these MTS databases which often contain several gigabytes of data. Surprisingly, research on MTS search is very limited. Most of the existing work only supports queries with the same length of data, or queries on a fixed set of variables. In this paper, we propose an efficient and flexible subsequence search framework for massive MTS databases, that, for the first time, enables querying on any subset of variables with arbitrary time delays between them. We propose two algorithms to solve this problem (1) a List Based Search (LBS) algorithm which uses sorted lists for indexing, and (2) a R*-tree Based Search (RBS) which uses Minimum Bounding Rectangles (MBR) to organize the subsequences. Both algorithms guarantee that all matching patterns within the specified thresholds will be returned (no false dismissals). The very few false alarms can be removed by a post-processing step. Since our framework is also capable of Univariate Time-Series (UTS) subsequence search, we first demonstrate the efficiency of our algorithms on several UTS datasets previously used in the literature. We follow this up with experiments using two large MTS databases from the aviation domain, each containing several millions of observations. Both these tests show that our algorithms have very high prune rates (>99%) thus needing actual disk access for only less than 1% of the observations. To the best of our knowledge, MTS subsequence search has never been attempted on datasets of the size we have used in this paper.

  6. Fast Analysis of Potential Scintillators Using Ion Time Of Flight

    NASA Astrophysics Data System (ADS)

    Milbrath, Brian; Zhang, Yanwen

    2008-05-01

    The development of scintillators for radiation applications such as national security, medical imaging, and experimental nuclear/particle physics has historically been rather slow, principally due to the developmental time necessary for large crystal growth. Scintillator crystals must achieve dimensions of a few mm before important characterizations, such as gamma ray energy resolution, can be performed. In order to facilitate accelerated discovery, we developed a time of flight (TOF) telescope for use on an ion beam. This allows individual determination of the ion energies prior to impinging the crystal, which may be a very thin prototype material. With such a technique, the scintillator performance in terms of energy resolution, light yield, decay time, and spectrum, can be determined quickly over a broad energy range. Though the analysis is performed using ions rather than the gamma-rays whose detection is the ultimate aim of the materials investigated, we have found useful correlations between the ion and gamma responses of the materials we have investigated (CaF2:Eu, YAP:Ce, BGO, CsI:Tl, and plastic scintillator). The technique appears to be able to rapidly determine whether a scintillator material has promise for further development.

  7. Peri-parturient rise of Cryptosporidium oocysts in cows: new insights provided by duplex quantitative real-time PCR.

    PubMed

    De Waele, Valérie; Berzano, Marco; Speybroeck, Niko; Berkvens, Dirk; Mulcahy, Grace M; Murphy, Thomas M

    2012-10-26

    In order to clarify if a peri-parturient rise of Cryptosporidium parvum oocysts occurs in cows, faecal samples from 42 cows on two farms were collected. These samples were taken during the pre-parturient, the peri-parturient and the post-parturient periods. Two methods were used to detect the oocysts, a nested-PCR coupled with sequencing and a duplex real-time PCR (qPCR) that quantified Cryptosporidium spp. DNA concentration. The qPCR results were adjusted using a hierarchical Bayesian model taking into account within and between run variation. Generalised Estimating Equation models (GEE) were used to determine if peri-parturient cows were at greater risk of being infected than pre- or post-parturient cows. Fourteen dairy cows exhibited a peri-parturient and post-parturient rise in the excretion of Cryptosporidium spp. oocysts, other than the zoonotic C. parvum. The cows in the suckler beef farm were the only ones infected with the zoonotic species C. parvum at calving. Due to the low concentration of oocysts excreted mainly from species other than C. parvum, it would appear unlikely that cows act as a source of infection for their calves or contribute significantly to environmental contamination. PMID:22681972

  8. RISE TIME DELAY DISCRIMINATOR

    DOEpatents

    Johnstone, C.W.

    1959-09-29

    A pulse-height discriminator for generating an output pulse when the accepted input pulse is approximately at its maximum value is described. A gating tube and a negative bias generator responsive to the derivative of the input pulse and means for impressing the output of the bias generator to at least one control electrode of the gating tube are included.

  9. Investigation on F layer height rise and equatorial spread F onset time: Signature of standing large-scale wave

    NASA Astrophysics Data System (ADS)

    Joshi, Lalit Mohan; Balwada, S.; Pant, T. K.; Sumod, S. G.

    2015-04-01

    Equatorial spread F observations have been categorized into three categories based on ionograms recorded over Sriharikota. First category comprised cases where the onset of equatorial spread F (ESF) was concurrent with the peak h'F time. Second and third categories comprised cases where the onset of ESF happened with a delay of 30 min and more than 30 min, respectively, with reference to the peak h'F time. Average peak h'F in the first category was more than 35 km higher than that in the second and third categories. Also, the peak vertical (upward) plasma drift was higher in the first category. Assuming the genesis of F region irregularity to have happened at or before the time of F layer attaining the peak height, late onset of ESF indicates the genesis of irregularities to have happened westward of Sriharikota. The fact that the peak h'F values were remarkably different in the three categories indicates a zonal variation of eastward electric field and postsunset height rise of F layer. The relative magnitude of the F layer height rise in the three different categories over Sriharikota has also been found to be significantly different than that over Thumba, an equatorial (magnetic) station located ~360 km westward of Sriharikota longitude. This scenario points toward the existence of a large-scale zonal standing wave in the F layer and its important role in F region instability process. Results presented in the manuscript have been discussed in the light of current understanding on the large-scale wave structure.

  10. Time variant cross correlation to assess residence time of water and implication for hydraulics of a sink-rise karst system

    NASA Astrophysics Data System (ADS)

    Bailly-Comte, V.; Martin, Jonathan B.; Screaton, E. J.

    2011-05-01

    Transport rates and residence time in the subsurface are critical parameters for understanding water-rock interactions for efficient contaminant remediation. This paper presents a methodology for assessing flow and transit time of water through hydrological systems, with specific applications to karst systems and implication for hydraulics of a conduit system surrounded by a porous and permeable intergranular matrix. A time variant cross-correlation function analysis is applied to bivariate time series that characterize mass transfer, assuming a stationary system using sliding windows of various sizes. We apply the method to 1 year long temperature records in the Santa Fe River (north central Florida) measured at (1) the River Sink, where all the incoming surface water drains into a sinkhole, (2) Sweetwater Lake, where the river resurges into a 500 m long karst window, and (3) the River Rise, where the water discharges from a first-magnitude karst spring. Results are compared with those obtained using specific conductivity. Estimated residence time ranges from less than 1 day during floods to more than 15 days during base flow within the 8000 m flow path between the River Sink and the River Rise. Results are used to characterize geometric, hydraulic, and hydrodynamic properties of this sink-rise system with strong matrix-conduit interactions. These properties are critical to the chemical and physical behavior of surface water-groundwater mixing. Our results also have direct implications for sampling strategies and hydrograph separation of many karst systems with different degrees and types of matrix porosity and permeability.

  11. A Fast-Time Simulation Tool for Analysis of Airport Arrival Traffic

    NASA Technical Reports Server (NTRS)

    Erzberger, Heinz; Meyn, Larry A.; Neuman, Frank

    2004-01-01

    The basic objective of arrival sequencing in air traffic control automation is to match traffic demand and airport capacity while minimizing delays. The performance of an automated arrival scheduling system, such as the Traffic Management Advisor developed by NASA for the FAA, can be studied by a fast-time simulation that does not involve running expensive and time-consuming real-time simulations. The fast-time simulation models runway configurations, the characteristics of arrival traffic, deviations from predicted arrival times, as well as the arrival sequencing and scheduling algorithm. This report reviews the development of the fast-time simulation method used originally by NASA in the design of the sequencing and scheduling algorithm for the Traffic Management Advisor. The utility of this method of simulation is demonstrated by examining the effect on delays of altering arrival schedules at a hub airport.

  12. Development of a novel voltage divider for measurement of sub-nanosecond rise time high voltage pulses

    NASA Astrophysics Data System (ADS)

    Mitra, S.; Senthil, K.; Singh, S. K.; Kumar, Ranjeet; Sharma, Archana

    2016-02-01

    This paper is about the development of a copper sulphate based aqueous-electrolytic voltage divider for the measurement of high voltage pulses, 100 kV, with pulse widths of 1-2 ns and rise time <1 ns. Novel features are incorporated in the design of the divider, to meet the performance requirements for the application. Analytical calculations to justify design are described. Structural simulation of the divider is carried out using field wave simulation software to verify the effectiveness. A calibration procedure has been developed to calibrate the divider. Results obtained during calibration are subjected to statistical analysis to determine the confidence of measurement. Details of design, analysis, and simulation are described in this paper.

  13. Fault plane orientations of microearthquakes at Mt. Etna from the inversion of P-wave rise times

    NASA Astrophysics Data System (ADS)

    de Lorenzo, Salvatore; Giampiccolo, Elisabetta; Martinez-Arevalo, Carmen; Patanè, Domenico; Romeo, Annalisa

    2010-01-01

    A crucial point in the analysis of tectonic earthquakes occurring in a volcanic area is the inference of the orientation of the structures along which the ruptures occur. These structures represent zones of weakness which could favor the migration of melt toward the surface and the assessment of their geometry is a fundamental step toward efficient evaluation of volcanic risk. We analyzed a high-quality dataset of 171 low-magnitude, tectonic earthquakes that occurred at Mt. Etna during the 2002-2003 eruption. We applied a recently developed technique aimed at inferring the source parameters (source size, dip and strike fault) and the intrinsic quality factor Qp of P waves from the inversion of rise times. The technique is based on numerically calibrated relationships among the rise time of first P waves and the source parameters for a circular crack rupturing at a constant velocity. For the most of the events the directivity source effect did not allow us to constrain the fault plane orientation. For a subset of 45 events with well constrained focal mechanisms we were able to constrain the "true" fault plane orientation. The level of resolution of the fault planes was assessed through a non linear analysis based on the random deviates technique. The significance of the retrieved fault plane solutions and the fit of the assumed source model to data were assessed through a χ-square test. Most of the retrieved fault plane solutions agree with the geometrical trend of known surface faults. The inferred source parameters and Qp are in agreement with the results of previous studies.

  14. A TRANSIT TIMING ANALYSIS OF NINE RISE LIGHT CURVES OF THE EXOPLANET SYSTEM TrES-3

    SciTech Connect

    Gibson, N. P.; Pollacco, D.; Simpson, E. K.; Barros, S.; Joshi, Y. C.; Todd, I.; Keenan, F. P.; Skillen, I.; Benn, C.; Christian, D.; Hrudkova, M.; Steele, I. A.

    2009-08-01

    We present nine newly observed transits of TrES-3, taken as part of a transit timing program using the RISE instrument on the Liverpool Telescope. A Markov-Chain Monte Carlo analysis was used to determine the planet-star radius ratio and inclination of the system, which were found to be R{sub p} /R {sub *} = 0.1664{sup +0.0011} {sub -0.0018} and i = 81.73{sup +0.13} {sub -0.04}, respectively, consistent with previous results. The central transit times and uncertainties were also calculated, using a residual-permutation algorithm as an independent check on the errors. A re-analysis of eight previously published TrES-3 light curves was conducted to determine the transit times and uncertainties using consistent techniques. Whilst the transit times were not found to be in agreement with a linear ephemeris, giving {chi}{sup 2} = 35.07 for 15 degrees of freedom, we interpret this to be the result of systematics in the light curves rather than a real transit timing variation. This is because the light curves that show the largest deviation from a constant period either have relatively little out-of-transit coverage or have clear systematics. A new ephemeris was calculated using the transit times and was found to be T{sub c} (0) = 2454632.62610 {+-} 0.00006 HJD and P = 1.3061864 {+-} 0.0000005 days. The transit times were then used to place upper mass limits as a function of the period ratio of a potential perturbing planet, showing that our data are sufficiently sensitive to have probed sub-Earth mass planets in both interior and exterior 2:1 resonances, assuming that the additional planet is in an initially circular orbit.

  15. Hydrothermal Mineral Deposits From a Young (0.1Ma) Abyssal Hill on the Flank of the Fast-Spreading East Pacific Rise

    NASA Astrophysics Data System (ADS)

    Benjamin, S. B.; Haymon, R. M.

    2004-12-01

    It has been estimated from heat flow measurements that at least 40% of the total hydrothermal heat lost from oceanic lithosphere is removed from 0.1-5 Ma abyssal hill terrain on mid-ocean ridge flanks. Despite the large magnitude of estimated hydrothermal heat loss from young abyssal hills, little is known about characteristics of hydrothermal vents and mineral deposits in this setting. This study describes the first abyssal hill hydrothermal samples to be collected on the flank of a fast-spreading ridge. The mineral deposits were discovered at "Tevnia Site" on the axis-facing fault scarp of an abyssal hill, located on ˜0.1 Ma lithosphere ˜5 km east of the East Pacific Rise (EPR) axis at 10\\deg 20'N. Observations of Galatheid crabs, "dandelion" siphonophores, and colonies of dead, yet still intact, Tevnia worm tubes at this site during Alvin dives in 1994 suggests relatively recent hydrothermal activity. The deposits are friable hydrothermal precipitates incorporating volcanic clasts brecciated at both the micro and macro scales. The petrographic sequence of brecciation, alteration, and cementation exhibited by the samples suggests that they formed from many pulses of hydrothermal venting interspersed with, and perhaps triggered by, repeated tectonic events as the abyssal hill was uplifted and moved off-axis (see also Haymon et al., this session). Observed minerals include x-ray amorphous opaline silica and Fe-oxide phases, crystalline Mn-oxides (birnessite and todorokite), an irregularly stratified mixed layer nontronite-celadonite, and residual calcite in sediment-derived microfossils incorporated into the breccia matrix. This mineral assemblage suggests that the deposits precipitated from moderately low-temperature (<140\\deg C) fluids, enriched in K, Fe, Si, and Mn, with a near-neutral pH. The presence of tubeworm casings at the site is evidence that the hydrothermal fluids carried H2S, however no metal sulfide phases were identified in the samples. Although

  16. Slow and Fast Transitions in the Rising Phase of Outbursts from NS-LMXB Transients, Aquila X-1 and 4U 1608-52

    NASA Astrophysics Data System (ADS)

    Asai, Kazumi; Matsuoka, Masaru; Mihara, Tatehiro; Sugizaki, Mutsumi; Serino, Motoko; Nakahira, Satoshi; Negoro, Hitoshi; Ueda, Yoshihiro; Yamaoka, Kazutaka

    2012-12-01

    We analyzed the initial rising behaviors of X-ray outbursts from two transient low-mass X-ray binaries (LMXBs) containing a neutron-star (NS), Aquila X-1 (Aql X-1) and 4U 1608-52, which are continuously being monitored by MAXI/GSC in 2-20 keV, RXTE/ASM in 2-10 keV, and Swift/BAT in 15-50 keV. We found that the observed ten outbursts can be classified into two types based on the patterns of the relative intensity evolutions in the two energy bands below/above 15 keV. One type behaves as the 15-50 keV intensity achieves the maximum during the initial hard-state period, and drops greatly at the hard-to-soft state transition. On the other hand, the other type does as both the 2-15 keV and 15-50 keV intensities achieve the maximums after the transition. The former have the longer initial hard-state (gtrsim 9 d) than the latter (lesssim 5 d). Therefore, we named them as slow-type (S-type) and fast-type (F-type), respectively. These two types also show differences in the luminosity at the hard-to-soft state transition as well as in the average luminosity before the outburst started, where the S-type are higher than the F-type in both. These results suggest that the X-ray radiation during the pre-outburst period, which heats up the accretion disk and delays the disk transition (i.e., from a geometrically thick disk to a thin one), would determine whether the following outburst becomes S-type or F-type. The luminosity when the hard-to-soft state transition occurs is higher than ˜8 × 1036 erg s-1 in the S-type, which corresponds to 4% of the Eddington luminosity for a 1.4 M⊙ NS.

  17. Fast Time and Space Parallel Algorithms for Solution of Parabolic Partial Differential Equations

    NASA Technical Reports Server (NTRS)

    Fijany, Amir

    1993-01-01

    In this paper, fast time- and Space -Parallel agorithms for solution of linear parabolic PDEs are developed. It is shown that the seemingly strictly serial iterations of the time-stepping procedure for solution of the problem can be completed decoupled.

  18. Copernicus Rising

    NASA Astrophysics Data System (ADS)

    Rose, Michael A.

    2007-08-01

    Copernicus Rising began as a historical biography when it was first conceived, but as the writing progressed it quickly became a rather absurd play that took historical research and twisted it through the lens of my own wit, philosophy and personal affection for the characters. When working with historical figures--characters who existed in a very tangible way in our own history--the playwriting process opens a dialogue between different points in time and space. The difficulty lies in finding a unique and clear voice amongst the discordant personalities involved in this time and space overlap, both in the writing and production processes, in order to get to the heart of what the play is really all about. This thesis follows the journey of the play from its historical roots through the creation of an absurd journey both insides and outside time, space and the human mind. The first part of the thesis explains the beginnings of the concept and outlines much of the research and development that went into the play. The next part outlines the process of production and integrating the world on paper with that of moving bodies on stage. In the final part, post-production discussions and audience feedback sessions shape the play into the draft included in this thesis.

  19. A comparative study of Type II-P and II-L supernova rise times as exemplified by the case of LSQ13cuw

    NASA Astrophysics Data System (ADS)

    Gall, E. E. E.; Polshaw, J.; Kotak, R.; Jerkstrand, A.; Leibundgut, B.; Rabinowitz, D.; Sollerman, J.; Sullivan, M.; Smartt, S. J.; Anderson, J. P.; Benetti, S.; Baltay, C.; Feindt, U.; Fraser, M.; González-Gaitán, S.; Inserra, C.; Maguire, K.; McKinnon, R.; Valenti, S.; Young, D.

    2015-10-01

    We report on our findings based on the analysis of observations of the Type II-L supernova LSQ13cuw within the framework of currently accepted physical predictions of core-collapse supernova explosions. LSQ13cuw was discovered within a day of explosion, hitherto unprecedented for Type II-L supernovae. This motivated a comparative study of Type II-P and II-L supernovae with relatively well-constrained explosion epochs and rise times to maximum (optical) light. From our sample of twenty such events, we find evidence of a positive correlation between the duration of the rise and the peak brightness. On average, SNe II-L tend to have brighter peak magnitudes and longer rise times than SNe II-P. However, this difference is clearest only at the extreme ends of the rise time versus peak brightness relation. Using two different analytical models, we performed a parameter study to investigate the physical parameters that control the rise time behaviour. In general, the models qualitatively reproduce aspects of the observed trends. We find that the brightness of the optical peak increases for larger progenitor radii and explosion energies, and decreases for larger masses. The dependence of the rise time on mass and explosion energy is smaller than the dependence on the progenitor radius. We find no evidence that the progenitors of SNe II-L have significantly smaller radii than those of SNe II-P. Appendices are available in electronic form at http://www.aanda.org

  20. Evaluation of Fast-Time Wake Vortex Models using Wake Encounter Flight Test Data

    NASA Technical Reports Server (NTRS)

    Ahmad, Nashat N.; VanValkenburg, Randal L.; Bowles, Roland L.; Limon Duparcmeur, Fanny M.; Gloudesman, Thijs; van Lochem, Sander; Ras, Eelco

    2014-01-01

    This paper describes a methodology for the integration and evaluation of fast-time wake models with flight data. The National Aeronautics and Space Administration conducted detailed flight tests in 1995 and 1997 under the Aircraft Vortex Spacing System Program to characterize wake vortex decay and wake encounter dynamics. In this study, data collected during Flight 705 were used to evaluate NASA's fast-time wake transport and decay models. Deterministic and Monte-Carlo simulations were conducted to define wake hazard bounds behind the wake generator. The methodology described in this paper can be used for further validation of fast-time wake models using en-route flight data, and for determining wake turbulence constraints in the design of air traffic management concepts.

  1. Fast timing study of a CeBr3 crystal: Time resolution below 120 ps at 60Co energies

    NASA Astrophysics Data System (ADS)

    Fraile, L. M.; Mach, H.; Vedia, V.; Olaizola, B.; Paziy, V.; Picado, E.; Udías, J. M.

    2013-02-01

    We report on the time response of a novel inorganic scintillator, CeBr3. The measurements were performed using a cylindrical crystal of 1-in. in height and 1-in. in diameter at 22Na and 60Co photon energies. The time response was measured against a fast reference BaF2 detector. Hamamatsu R9779 and Photonis XP20D0 fast photomultipliers (PMTs) were used. The PMT bias voltages and Constant Fraction Discriminator settings were optimized with respect to the timing resolution. The Full Width at Half Maximum (FWHM) time resolution for an individual CeBr3 crystal coupled to Hamamatsu PMT is found here to be as low as 119 ps at 60Co energies, which is comparable to the resolution of 107 ps reported for LaBr3(Ce). For 511 keV photons the measured FWHM time resolution for CeBr3 coupled to the Hamamatsu PMT is 164 ps.

  2. Analog electro-optical readout of SiPMs achieves fast timing required for time-of-flight PET/MR.

    PubMed

    Bieniosek, M F; Levin, C S

    2015-05-01

    The design of combined positron emission tomography/magnetic resonance (PET/MR) systems presents a number of challenges to engineers, as it forces the PET system to acquire data in a space constrained environment that is sensitive to electro-magnetic interference and contains high static, radio frequency and gradient fields. In this work we validate fast timing performance of a PET scintillation detector using a potentially very compact, very low power, and MR compatible readout method in which analog silicon photomultipliers (SiPM) signals are transmitted optically away from the MR bore with little or even no additional readout electronics. This analog 'electro-optial' method could reduce the entire PET readout in the MR bore to two compact, low power components (SiPMs and lasers). Our experiments show fast timing performance from analog electro-optical readout with and without pre-amplification. With 3 mm × 3 mm × 20 mm lutetium-yttrium oxyorthosilicate (LYSO) crystals and Excelitas SiPMs the best two-sided fwhm coincident timing resolution achieved was 220 +/- 3 ps in electrical mode, 230 +/- 2 ps in electro-optical with preamp mode, and 253 +/- 2 ps in electro-optical without preamp mode. Timing measurements were also performed with Hamamatsu SiPMs and 3 mm × 3 mm × 5 mm crystals. In the future the timing degradation seen can be further reduced with lower laser noise or improvements SiPM rise time or gain. PMID:25905626

  3. Crustal structure in the ROSE area of the East Pacific Rise: One-dimensional travel time inversion of sonobuoys and expanded spread profiles

    NASA Astrophysics Data System (ADS)

    Vera, Emilio E.; Mutter, John C.

    1988-06-01

    We study the variability of the young oceanic crust as a function of age by analyzing 11 digitally recorded sonobuoys and three expanded spread profiles over 0.5-, 2.5-, and 4.5-m.y.-old oceanic crust. The data were collected during the Rivera Ocean Seismic Experiment at the East Pacific Rise between 11° and 13°N. We analyze the data within a one-dimensional travel time scheme using the tau-p method and travel time forward modeling. We perform the tau-p mapping by using a polynomial least squares technique that is fast and can be applied even to poor quality data as in this case. We do not see large changes in the velocity structure between 0.5-and 4.5-m.y.-old oceanic crust. The overall structure consists of a rapid increase in velocity from about 2.5-6 km/s within the uppermost 1 km of crust (layer 2A), a zone ≤1 km in thickness with little or no velocity gradient (layer 2B), a thin transition layer with a relatively rapid increase in velocity from about 6.2 to 7 km/s (layer 2C), and a thick nearly homogeneous basal layer with velocities around 7.2 km/s (layer 3). We find that the low velocities at the seafloor and large velocity gradients within the shallow crust can be explained by the hypothesis of large-scale cracks and their behavior under confining pressure. For the variation of velocity V versus depth below seafloor z, this hypothesis yields V = (V02 + Bz)1/2, a relationship that fits our solutions.

  4. A signal distribution board for the timing and fast control master of the CBM experiment

    NASA Astrophysics Data System (ADS)

    Meder, L.; Dreschmann, M.; Sander, O.; Becker, J.

    2016-02-01

    For the CBM experiment a Timing and Fast-Control (TFC) system is being developed. In the detector readout, FPGA-based data processing boards (DPB) are organized in a large number of computing crates. At the crate level, the TFC master is connected to one TFC slave per crate, whereas the DPB AMCs are interconnected by the crates' infrastructure. In this article, an FMC-based signal distribution board is proposed allowing the transmission of a high-quality clock and timing and fast-control data from and to connected TFC slaves at distances of about 30 meters using twisted-pair cables.

  5. Fast X-ray micro-CT for real-time 4D observation

    NASA Astrophysics Data System (ADS)

    Takano, H.; Yoshida, K.; Tsuji, T.; Koyama, T.; Tsusaka, Y.; Kagoshima, Y.

    2009-09-01

    Fast X-ray computed tomography (CT) system with sub-second order measurement for single CT acquisition has been developed. The system, consisting of a high-speed sample rotation stage and a high-speed X-ray camera, is constructed at synchrotron radiation beamline in order to utilize fully intense X-rays. A time-resolving CT movie (i.e. 4D CT) can be available by operating the fast CT system continuously. Real-time observation of water absorbing process of super-absorbent polymer (SAP) has been successfully performed with the 4D CT operation.

  6. Mesoscale Simulation Data for Initializing Fast-Time Wake Transport and Decay Models

    NASA Technical Reports Server (NTRS)

    Ahmad, Nashat N.; Proctor, Fred H.; Vanvalkenburg, Randal L.; Pruis, Mathew J.; LimonDuparcmeur, Fanny M.

    2012-01-01

    The fast-time wake transport and decay models require vertical profiles of crosswinds, potential temperature and the eddy dissipation rate as initial conditions. These inputs are normally obtained from various field sensors. In case of data-denied scenarios or operational use, these initial conditions can be provided by mesoscale model simulations. In this study, the vertical profiles of potential temperature from a mesoscale model were used as initial conditions for the fast-time wake models. The mesoscale model simulations were compared against available observations and the wake model predictions were compared with the Lidar measurements from three wake vortex field experiments.

  7. Fast photochromism in polymer matrix with plasticizer and real-time dynamic holographic properties

    NASA Astrophysics Data System (ADS)

    Ishii, Norihito; Abe, Jiro

    2013-04-01

    We have developed a photochromic polymer film for the use of real-time dynamic hologram, fabricated by the plasticized polymer doped with the fast photochromic molecule. The addition of a plasticizer into the conventional polymer is proved to be effective to improve the photochromic performances for the polymer film doped with the fast photochromic molecule that shows instantaneous coloration upon exposure to UV light and rapid fading in the dark. The plasticized photochromic polymers enable the real-time control of the writing and erasing of a holographic grating and show a higher recording sensitivity compared with other organic holographic materials.

  8. Ultra-fast consensus of discrete-time multi-agent systems under a unified framework

    NASA Astrophysics Data System (ADS)

    Zhang, Wenle; Liu, Jianchang

    2015-06-01

    This paper deals with the ultra-fast consensus problem of high-order discrete-time multi-agent systems under a unified framework. A multi-step neighbour-error predictive mechanism is established based on the future evolution of the network dynamic without predictive information. By predicting the dynamics of a network several steps ahead and adding this information into the consensus protocol, a novel ultra-fast consensus protocol with the self-feedback term is proposed. The asymptotic convergence factor is improved by a power of q + 1 compared to the routine consensus protocol. The ultra-fast consensus algorithm can overcome the influence of communication topology to the convergence speed toward consensus, and solve the difficult problem of selecting the optimal control gain which minimises the asymptotic convergence factor. Moveover, some sufficient conditions for ultra-fast consensus design are given herein. The ones decouple the design of the synchronising gains from the detailed graph properties, and explicitly reveal how the agent dynamic and the communication graph jointly affect ultra-fast consensus of discrete-time multi-agent systems. A simulation is performed to illustrate the effectiveness of the theoretical results.

  9. Natural fast speech is perceived as faster than linearly time-compressed speech.

    PubMed

    Reinisch, Eva

    2016-05-01

    Listeners compensate for variation in speaking rate: In a fast context, a given sound is interpreted as longer than in a slow context. Experimental rate manipulations have been achieved either through linear compression or by using natural fast speech. However, in natural fast speech, segments are subject to processes such as reduction or deletion. If speaking rate is then defined as the number of segments per unit time, the question arises as to what impact such processes have on listeners' normalization for speaking rate. The present study tested the effect of sentence duration and fast-speech processes on rate normalization for a German vowel duration contrast. Results showed that a naturally produced short sentence containing segmental reductions and deletions led to the most "long" vowel responses whereas the long sentence with clearly articulated segments led to the fewest. This suggests that speaking rate is not merely calculated as the number of segments realized per unit time. Rather, listeners associate properties of natural fast speech with a higher speaking rate. This contrasts with earlier results and a second experiment in which perceived speaking rate was measured in an explicit task. Models of speech comprehension are evaluated with regard to the present findings. PMID:26860711

  10. Waveform timing performance of a 5 GS/s fast pulse sampling module with DRS4

    NASA Astrophysics Data System (ADS)

    Wang, Jin-Hong; Liu, Shu-Bin; An, Qi

    2015-10-01

    We first clarify timing issues of non-uniform sampling intervals regarding a 5 GS/s fast pulse sampling module with DRS4. A calibration strategy is proposed, and as a result, the waveform timing performance is improved to below 10 ps RMS. We then further evaluate waveform-timing performance of the module by comparing with a 10 GS/s oscilloscope in a setup with plastic scintillators and fast PMTs. Different waveform timing algorithms are employed for analysis, and the module shows comparable timing performance with that of the oscilloscope. Supported by Knowledge Innovation Program of the Chinese Academy of Sciences (KJCX2-YW-N27), and National Natural Science Foundation of China (11175176)

  11. Demonstration of two-dimensional time-encoded imaging of fast neutrons

    DOE PAGESBeta

    Brennan, J.; Brubaker, E.; Gerling, M.; Marleau, P.; McMillan, K.; Nowack, A.; Galloudec, N. Renard-Le; Sweany, M.

    2015-09-09

    Here, we present a neutron detector system based on time-encoded imaging, and demonstrate its applicability toward the spatial mapping of special nuclear material. We also demonstrate that two-dimensional fast-neutron imaging with 2° resolution at 2 m stand-off is feasible with only two instrumented detectors.

  12. Recovery time course in contractile function of fast and slow skeletal muscle after hindlimb immobilization

    NASA Technical Reports Server (NTRS)

    Witzmann, F. A.; Kim, D. H.; Fitts, R. H.

    1982-01-01

    The present study was undertaken to characterize the time course and extent of recovery in the isometric and isotonic contractile properties of fast and slow skeletal muscle following 6 wk of hindlimb immobilization. Female Sprague-Dawley rats were randomly assigned to an immobilized group or a control group. The results of the study show that fast and slow skeletal muscles possess the ability to completely recover normal contractile function following 6 wk of hindlimb immobilization. The rate of recovery is dependent on the fiber type composition of the affected muscle.

  13. Wide dynamic range neutron flux monitor having fast time response for the Large Helical Device.

    PubMed

    Isobe, M; Ogawa, K; Miyake, H; Hayashi, H; Kobuchi, T; Nakano, Y; Watanabe, K; Uritani, A; Misawa, T; Nishitani, T; Tomitaka, M; Kumagai, T; Mashiyama, Y; Ito, D; Kono, S; Yamauchi, M; Takeiri, Y

    2014-11-01

    A fast time response, wide dynamic range neutron flux monitor has been developed toward the LHD deuterium operation by using leading-edge signal processing technologies providing maximum counting rate up to ∼5 × 10(9) counts/s. Because a maximum total neutron emission rate over 1 × 10(16) n/s is predicted in neutral beam-heated LHD plasmas, fast response and wide dynamic range capabilities of the system are essential. Preliminary tests have demonstrated successful performance as a wide dynamic range monitor along the design. PMID:25430293

  14. Wide dynamic range neutron flux monitor having fast time response for the Large Helical Device

    SciTech Connect

    Isobe, M. Takeiri, Y.; Ogawa, K.; Miyake, H.; Hayashi, H.; Kobuchi, T.; Nakano, Y.; Watanabe, K.; Uritani, A.; Misawa, T.; Nishitani, T.; Tomitaka, M.; Kumagai, T.; Mashiyama, Y.; Ito, D.; Kono, S.; Yamauchi, M.

    2014-11-15

    A fast time response, wide dynamic range neutron flux monitor has been developed toward the LHD deuterium operation by using leading-edge signal processing technologies providing maximum counting rate up to ∼5 × 10{sup 9} counts/s. Because a maximum total neutron emission rate over 1 × 10{sup 16} n/s is predicted in neutral beam-heated LHD plasmas, fast response and wide dynamic range capabilities of the system are essential. Preliminary tests have demonstrated successful performance as a wide dynamic range monitor along the design.

  15. Relationship between ridge segmentation and Moho transition zone structure from 3D multichannel seismic data collected over the fast-spreading East Pacific Rise at 9°50'N

    NASA Astrophysics Data System (ADS)

    Aghaei, O.; Nedimovic, M. R.; Canales, J.; Carton, H. D.; Carbotte, S. M.; Mutter, J. C.

    2010-12-01

    We present stack and migrated stack volumes of a fast-spreading center produced from the high-resolution 3D multichannel seismic (MCS) data collected in summer of 2008 over the East Pacific Rise (EPR) at 9°50’N during cruise MGL0812. These volumes give us new insight into the 3D structure of the lower crust and Moho Transition Zone (MTZ) along and across the ridge axis, and how this structure relates to the ridge segmentation at the spreading axis. The area of 3D coverage is between 9°38’N and 9°58’N (~1000 km2) where the documented eruptions of 1990-91 and 2005-06 occurred. This high-resolution survey has a nominal bin size of 6.25 m in cross-axis direction and 37.5 m in along-axis direction. The prestack processing sequence applied to data includes 1D and 2D filtering to remove low-frequency cable noise, offset-dependent spherical divergence correction to compensate for geometrical spreading, surface-consistent amplitude correction to balance abnormally high/low shot and channel amplitudes, trace editing, velocity analysis, normal moveout (NMO), and CMP mute of stretched far offset arrivals. The poststack processing includes seafloor multiple mute to reduce migration noise and poststack time migration. We also will apply primary multiple removal and prestack time migration to the data and compare the results to the migrated stack volume. The poststack and prestack migrated volumes will then be used to detail Moho seismic signature variations and their relationship to ridge segmentation, crustal age, bathymetry, and magmatism. We anticipate that the results will also provide insight into the mantle upwelling pattern, which is actively debated for the study area.

  16. Fast damage imaging using the time-reversal technique in the frequency-wavenumber domain

    NASA Astrophysics Data System (ADS)

    Zhu, R.; Huang, G. L.; Yuan, F. G.

    2013-07-01

    The time-reversal technique has been successfully used in structural health monitoring (SHM) for quantitative imaging of damage. However, the technique is very time-consuming when it is implemented in the time domain. In this paper, we study the technique in the frequency-wavenumber (f-k) domain for fast real-time imaging of multiple damage sites in plates using scattered flexural plate waves. Based on Mindlin plate theory, the time reversibility of dispersive flexural waves in an isotropic plate is theoretically investigated in the f-k domain. A fast damage imaging technique is developed by using the cross-correlation between the back-propagated scattered wavefield and the incident wavefield in the frequency domain. Numerical simulations demonstrate that the proposed technique cannot only localize multiple damage sites but also potentially identify their sizes. Moreover, the time-reversal technique in the f-k domain is about two orders of magnitude faster than the method in the time domain. Finally, experimental testing of an on-line SHM system with a sparse piezoelectric sensor array is conducted for fast multiple damage identification using the proposed technique.

  17. A novel fast gas chromatography method for higher time resolution measurements of speciated monoterpenes in air

    NASA Astrophysics Data System (ADS)

    Jones, C. E.; Kato, S.; Nakashima, Y.; Kajii, Y.

    2014-05-01

    Biogenic emissions supply the largest fraction of non-methane volatile organic compounds (VOC) from the biosphere to the atmospheric boundary layer, and typically comprise a complex mixture of reactive terpenes. Due to this chemical complexity, achieving comprehensive measurements of biogenic VOC (BVOC) in air within a satisfactory time resolution is analytically challenging. To address this, we have developed a novel, fully automated Fast Gas Chromatography (Fast-GC) based technique to provide higher time resolution monitoring of monoterpenes (and selected other C9-C15 terpenes) during plant emission studies and in ambient air. To our knowledge, this is the first study to apply a Fast-GC based separation technique to achieve quantification of terpenes in ambient air. Three chromatography methods have been developed for atmospheric terpene analysis under different sampling scenarios. Each method facilitates chromatographic separation of selected BVOC within a significantly reduced analysis time compared to conventional GC methods, whilst maintaining the ability to quantify individual monoterpene structural isomers. Using this approach, the C9-C15 BVOC composition of single plant emissions may be characterised within a 14.5 min analysis time. Moreover, in-situ quantification of 12 monoterpenes in unpolluted ambient air may be achieved within an 11.7 min chromatographic separation time (increasing to 19.7 min when simultaneous quantification of multiple oxygenated C9-C10 terpenoids is required, and/or when concentrations of anthropogenic VOC are significant). These analysis times potentially allow for a twofold to fivefold increase in measurement frequency compared to conventional GC methods. Here we outline the technical details and analytical capability of this chromatographic approach, and present the first in-situ Fast-GC observations of 6 monoterpenes and the oxygenated BVOC (OBVOC) linalool in ambient air. During this field deployment within a suburban forest

  18. Fast Mapping Across Time: Memory Processes Support Children’s Retention of Learned Words

    PubMed Central

    Vlach, Haley A.; Sandhofer, Catherine M.

    2012-01-01

    Children’s remarkable ability to map linguistic labels to referents in the world is commonly called fast mapping. The current study examined children’s (N = 216) and adults’ (N = 54) retention of fast-mapped words over time (immediately, after a 1-week delay, and after a 1-month delay). The fast mapping literature often characterizes children’s retention of words as consistently high across timescales. However, the current study demonstrates that learners forget word mappings at a rapid rate. Moreover, these patterns of forgetting parallel forgetting functions of domain-general memory processes. Memory processes are critical to children’s word learning and the role of one such process, forgetting, is discussed in detail – forgetting supports extended mapping by promoting the memory and generalization of words and categories. PMID:22375132

  19. Fast-ball sports experts depend on an inhibitory strategy to reprogram their movement timing.

    PubMed

    Nakamoto, Hiroki; Ikudome, Sachi; Yotani, Kengo; Maruyama, Atsuo; Mori, Shiro

    2013-07-01

    The purpose of our study was to clarify whether an inhibitory strategy is used for reprogramming of movement timing by experts in fast-ball sports when they correct their movement timing due to unexpected environmental changes. We evaluated the influence of disruption of inhibitory function of the right inferior frontal gyrus (rIFG) on reprogramming of movement timing of experts and non-experts in fast-ball sports. The task was to manually press a button to coincide with the arrival of a moving target. The target moved at a constant velocity, and its velocity was suddenly either increased or decreased in some trials. The task was performed either with or without transcranial magnetic stimulation (TMS), which was delivered to the region of the rIFG. Under velocity change conditions without TMS, the experts showed significantly smaller timing errors and a higher rate of reprogramming of movement timing than the non-experts. Moreover, TMS application during the task significantly diminished the expert group's performance, but not the control group, particularly in the condition where the target velocity decreases. These results suggest that experts use an inhibitory strategy for reprogramming of movement timing. In addition, the rIFG inhibitory function contributes to the superior movement correction of experts in fast-ball sports. PMID:23660742

  20. New Evidence for the Role of Emerging Flux in a Solar Filament's Slow Rise Preceding its CME-Producing Fast Eruption

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Harra, Louis K.; Moore, Ronald L.

    2007-01-01

    We observe the eruption of a large-scale (approx.300,000 km) quiet-region solar filament, leading to an Earth-directed "halo" coronal mass ejection (CME). We use coronal imaging data in EUV from the EUV Imaging Telescope (EIT) on the Solar and Heliospheric Observatory (SOHO) satellite, and in soft X-rays (SXRs) from the Soft X-ray Telescope (SXT) on the Yohkoh satellite. We also use spectroscopic data from the Coronal Diagnostic Spectrometer (CDS), magnetic data from the Michelson Doppler Imager (MDI), and white-light coronal data from the Large Angle and Spectrometric Coronagraph Experiment (LASCO), all on SOHO. Initially the filament shows a slow (approx.1 km/s projected against the solar disk) and approximately constant-velocity rise for about 6 hours, before erupting rapidly, reaching a velocity of approx. 8 km/s over the next approx. 25 min. CDS Doppler data show Earth-directed filament velocities ranging from < 20 km/s (the noise limit) during the slow-rise phase, to approx. 100 km/s-1 early in the eruption. Beginning within 10 hours prior to the start of the slow rise, localized new magnetic flux emerged near one end of the filament. Near the start of and during the slow-rise phase, SXR microflaring occurred repeatedly at the flux-emergence site, in conjunction with the development of a fan of SXR illumination of the magnetic arcade over the filament. The SXR microflares, development of the SXR fan, and motion of the slow-rising filament are all consistent with "tether-weakening" reconnection occurring between the newly-emerging flux and the overlying arcade field containing the filament field. The microflares and fan structure are not prominent in EUV, and would not have been detected without the SXR data. Standard "twin dimmings" occur near the location of the filament, and "remote dimmings" and "brightenings" occur further removed from the filament.

  1. Fast time-reversible algorithms for molecular dynamics of rigid-body systems.

    PubMed

    Kajima, Yasuhiro; Hiyama, Miyabi; Ogata, Shuji; Kobayashi, Ryo; Tamura, Tomoyuki

    2012-06-21

    In this paper, we present time-reversible simulation algorithms for rigid bodies in the quaternion representation. By advancing a time-reversible algorithm [Y. Kajima, M. Hiyama, S. Ogata, and T. Tamura, J. Phys. Soc. Jpn. 80, 114002 (2011)] that requires iterations in calculating the angular velocity at each time step, we propose two kinds of iteration-free fast time-reversible algorithms. They are easily implemented in codes. The codes are compared with that of existing algorithms through demonstrative simulation of a nanometer-sized water droplet to find their stability of the total energy and computation speeds. PMID:22779579

  2. A real-time dynamic holographic material using a fast photochromic molecule

    PubMed Central

    Ishii, Norihito; Kato, Tetsuya; Abe, Jiro

    2012-01-01

    We have developed a real-time, dynamic holographic material that exhibits rapid colouration upon irradiation with UV light and successive fast thermal bleaching within tens of milliseconds at room temperature. Photochromic polymer films were prepared by a simple solution-casting method from the benzene solution of the mixture of the photochromic molecule, poly(ethyl acrylate), and poly(phenoxyethyl acrylate). The real-time control of holographic images using the photochromic polymer film yields a speed equivalent to the time resolution of the human eye. This new type of dynamic holographic material based on fast photochromism opens up an exciting new area of research in the future development of a large dynamic 3D display. PMID:23139865

  3. A real-time dynamic holographic material using a fast photochromic molecule

    NASA Astrophysics Data System (ADS)

    Ishii, Norihito; Kato, Tetsuya; Abe, Jiro

    2012-11-01

    We have developed a real-time, dynamic holographic material that exhibits rapid colouration upon irradiation with UV light and successive fast thermal bleaching within tens of milliseconds at room temperature. Photochromic polymer films were prepared by a simple solution-casting method from the benzene solution of the mixture of the photochromic molecule, poly(ethyl acrylate), and poly(phenoxyethyl acrylate). The real-time control of holographic images using the photochromic polymer film yields a speed equivalent to the time resolution of the human eye. This new type of dynamic holographic material based on fast photochromism opens up an exciting new area of research in the future development of a large dynamic 3D display.

  4. The Commensal Real-Time ASKAP Fast-Transients (CRAFT) Survey

    NASA Astrophysics Data System (ADS)

    Macquart, Jean-Pierre; Bailes, M.; Bhat, N. D. R.; Bower, G. C.; Bunton, J. D.; Chatterjee, S.; Colegate, T.; Cordes, J. M.; D'Addario, L.; Deller, A.; Dodson, R.; Fender, R.; Haines, K.; Halll, P.; Harris, C.; Hotan, A.; Johnston, S.; Jones, D. L.; Keith, M.; Koay, J. Y.; Lazio, T. J. W.; Majid, W.; Murphy, T.; Navarro, R.; Phillips, C.; Quinn, P.; Preston, R. A.; Stansby, B.; Stairs, I.; Stappers, B.; Staveley-Smith, L.; Tingay, S.; Thompson, D.; van Straten, W.; Wagstaff, K.; Warren, M.; Wayth, R.; Wen, L.; CRAFT Collaboration

    2010-06-01

    We are developing a purely commensal survey experiment for fast (<5 s) transient radio sources. Short-timescale transients are associated with the most energetic and brightest single events in the Universe. Our objective is to cover the enormous volume of transients parameter space made available by ASKAP, with an unprecedented combination of sensitivity and field of view. Fast timescale transients open new vistas on the physics of high brightness temperature emission,extreme states of matter and the physics of strong gravitational fields. In addition, the detection of extragalactic objects affords us an entirely new and extremely sensitive probe on the huge reservoir of baryons present in the IGM. We outline here our approach to the considerable challenge involved in detecting fast transients, particularly the development of hardware fast enough to dedisperse and search the ASKAP data stream at or near real-time rates. Through CRAFT, ASKAP will provide the testbed of many of the key technologies and survey modes proposed for high time resolution science with the SKA.

  5. Investigation of the rise time and damping of spin excitations in Ni{sub 81}Fe{sub 19} thin films

    SciTech Connect

    Wu, J.; Hughes, N. D.; Moore, J. R.; Hicken, R. J.

    2001-06-01

    The rise and damping of spin excitations in three Ni{sub 81}Fe{sub 19} films of thickness 50, 500, and 5000 Aa have been studied with an optical pump{endash}probe technique in which the sample is pumped with an optically triggered magnetic field pulse. The motion of the magnetization was described by the uniform mode solution of the Landau{endash}Lifshitz{endash}Gilbert equation. The rise time of the pulsed field within the film was smallest in the 50 Aa sample and was generally greater when the pulsed field was perpendicular to the film plane. The damping constant was smallest in the 500 Aa sample. The variations in the rise time and damping are attributed to the presence of eddy currents and structural disorder in the films. Under certain excitation conditions a second mode was observed in the 5000 Aa sample which we believe to be a magnetostatic surface mode. {copyright} 2001 American Institute of Physics.

  6. Fast monitoring of epileptic seizures using recurrence time statistics of electroencephalography.

    PubMed

    Gao, Jianbo; Hu, Jing

    2013-01-01

    Epilepsy is a relatively common brain disorder which may be very debilitating. Currently, determination of epileptic seizures often involves tedious, time-consuming visual inspection of electroencephalography (EEG) data by medical experts. To better monitor seizures and make medications more effective, we propose a recurrence time based approach to characterize brain electrical activity. Recurrence times have a number of distinguished properties that make it very effective for forewarning epileptic seizures as well as studying propagation of seizures: (1) recurrence times amount to periods of periodic signals, (2) recurrence times are closely related to information dimension, Lyapunov exponent, and Kolmogorov entropy of chaotic signals, (3) recurrence times embody Shannon and Renyi entropies of random fields, and (4) recurrence times can readily detect bifurcation-like transitions in dynamical systems. In particular, property (4) dictates that unlike many other non-linear methods, recurrence time method does not require the EEG data be chaotic and/or stationary. Moreover, the method only contains a few parameters that are largely signal-independent, and hence, is very easy to use. The method is also very fast-it is fast enough to on-line process multi-channel EEG data with a typical PC. Therefore, it has the potential to be an excellent candidate for real-time monitoring of epileptic seizures in a clinical setting. PMID:24137126

  7. Summary of Sonic Boom Rise Times Observed During FAA Community Response Studies over a 6-Month Period in the Oklahoma City Area

    NASA Technical Reports Server (NTRS)

    Maglieri, Domenic J.; Sothcott, Victor E.

    1990-01-01

    The sonic boom signature data acquired from about 1225 supersonic flights, over a 6-month period in 1964 in the Oklahoma City area, was enhanced with the addition of data relating to rise times and total signature duration. These later parameters, not available at the time of publication of the original report on the Oklahoma City sonic boom exposures, are listed in tabular form along with overpressure, positive impulse, positive duration, and waveform category. Airplane operating information along with the surface weather observations are also included. Sonic boom rise times include readings to the 1/2, 3/4, and maximum overpressure values. Rise time relative probabilities for various lateral locations from the ground track of 0, 5, and 10 miles are presented along with the variation of rise times with flight altitude. The tabulated signature data, along with corresponding airplane operating conditions and surface and upper level atmospheric information, are also available on electronic files to provide it in the format for more efficient and effective utilization.

  8. "Fast" Is Not "Real-Time": Designing Effective Real-Time AI Systems

    NASA Astrophysics Data System (ADS)

    O'Reilly, Cindy A.; Cromarty, Andrew S.

    1985-04-01

    Realistic practical problem domains (such as robotics, process control, and certain kinds of signal processing) stand to benefit greatly from the application of artificial intelligence techniques. These problem domains are of special interest because they are typified by complex dynamic environments in which the ability to select and initiate a proper response to environmental events in real time is a strict prerequisite to effective environmental interaction. Artificial intelligence systems developed to date have been sheltered from this real-time requirement, however, largely by virtue of their use of simplified problem domains or problem representations. The plethora of colloquial and (in general) mutually inconsistent interpretations of the term "real-time" employed by workers in each of these domains further exacerbates the difficul-ties in effectively applying state-of-the-art problem solving tech-niques to time-critical problems. Indeed, the intellectual waters are by now sufficiently muddied that the pursuit of a rigorous treatment of intelligent real-time performance mandates the redevelopment of proper problem perspective on what "real-time" means, starting from first principles. We present a simple but nonetheless formal definition of real-time performance. We then undertake an analysis of both conventional techniques and AI technology with respect to their ability to meet substantive real-time performance criteria. This analysis provides a basis for specification of problem-independent design requirements for systems that would claim real-time performance. Finally, we discuss the application of these design principles to a pragmatic problem in real-time signal understanding.

  9. A Fast-Time Simulation Environment for Airborne Merging and Spacing Research

    NASA Technical Reports Server (NTRS)

    Bussink, Frank J. L.; Doble, Nathan A.; Barmore, Bryan E.; Singer, Sharon

    2005-01-01

    As part of NASA's Distributed Air/Ground Traffic Management (DAG-TM) effort, NASA Langley Research Center is developing concepts and algorithms for merging multiple aircraft arrival streams and precisely spacing aircraft over the runway threshold. An airborne tool has been created for this purpose, called Airborne Merging and Spacing for Terminal Arrivals (AMSTAR). To evaluate the performance of AMSTAR and complement human-in-the-loop experiments, a simulation environment has been developed that enables fast-time studies of AMSTAR operations. The environment is based on TMX, a multiple aircraft desktop simulation program created by the Netherlands National Aerospace Laboratory (NLR). This paper reviews the AMSTAR concept, discusses the integration of the AMSTAR algorithm into TMX and the enhancements added to TMX to support fast-time AMSTAR studies, and presents initial simulation results.

  10. Sensitivity Analysis of Reprocessing Cooling Times on Light Water Reactor and Sodium Fast Reactor Fuel Cycles

    SciTech Connect

    R. M. Ferrer; S. Bays; M. Pope

    2008-04-01

    The purpose of this study is to quantify the effects of variations of the Light Water Reactor (LWR) Spent Nuclear Fuel (SNF) and fast reactor reprocessing cooling time on a Sodium Fast Reactor (SFR) assuming a single-tier fuel cycle scenario. The results from this study show the effects of different cooling times on the SFR’s transuranic (TRU) conversion ratio (CR) and transuranic fuel enrichment. Also, the decay heat, gamma heat and neutron emission of the SFR’s fresh fuel charge were evaluated. A 1000 MWth commercial-scale SFR design was selected as the baseline in this study. Both metal and oxide CR=0.50 SFR designs are investigated.

  11. AQUA: a very fast automatic reduction pipeline for near real-time GRBs early afterglow detection

    NASA Astrophysics Data System (ADS)

    Di Paola, Andrea; Antonelli, Lucio A.; Testa, Vincenzo; Patria, Giorgio

    2002-12-01

    AQUA (Automated QUick Analysis) is the fast reduction pipeline of the Near Infra-Red (NIR) images obtained by the REM telescope. REM (Rapid Eye Mount) is a robotic NIR/Optical 60cm telescope for fast detection of early afterglow of Gamma Ray Bursts (GRB). NIR observations of GRBs early afterglow are of crucial importance for GRBs science, revealing even optical obscured or high redshift events. On the technical side, they pose a series of problems: luminous background, bright sources (as the counterparts should be observed few seconds after the satellite trigger) and fast detection force high rate images acquisition. Even if the observational strategy will change during the same event observation depending on the counterpart characteristics, we will start with 1 second exposures at the fastest possible rate. The main guideline in the AQUA pipeline development is to allow such a data rate along all the night with nearly real-time results delivery. AQUA will start from the raw images and will deliver an alert with coordinates, photometry and colors to larger telescopes to allow prompt spectroscopic and polarimetric observations. Very fast processing for the raw 512×512 32bit images and variable sources detection with both sources catalogs and images comparison have been implemented to obtain a processing speed of at least 1 image/sec. AQUA is based on ANSI-C code optimized to run on a dual Athlon Linux PC with careful MMX and SSE instructions utilization.

  12. In-beam fast-timing measurements in {sup 103,105,107}Cd

    SciTech Connect

    Kisyov, S.; Lalkovski, S.; Radulov, D.; Zhekova, M.; Marginean, N.; Bucurescu, D.; Cata-Danil, Gh.; Cata-Danil, I.; Deleanu, D.; Filipescu, D.; Ghita, D.; Glodariu, T.; Marginean, R.; Mihai, C.; Negret, A.; Pascu, S.; Sava, T.; Stroe, L.; Suliman, G.; Zamfir, N. V.

    2011-07-15

    Fast-timing measurements were performed in the region of the medium-mass {sup 103,105,107}Cd isotopes, produced in fusion evaporation reactions. Results on new and reevaluated half-lives are analyzed within a systematic study of transition rates. The 7/2{sub 1}{sup +} states in {sup 103,105,107}Cd are interpreted as arising from a single-particle excitation. The 9/2{sup +} states configuration assignment is based on the observed decay branches.

  13. Impact of Miscanthus x giganteus senescence times on fast pyrolysis bio-oil quality.

    PubMed

    Mos, M; Banks, S W; Nowakowski, D J; Robson, P R H; Bridgwater, A V; Donnison, I S

    2013-02-01

    In this study the impact of senescence and harvest time in Miscanthus on the quality of fast pyrolysis liquid (bio-oil) was investigated. Bio-oil was produced using a 1 kg h(-1) fast pyrolysis reactor to obtain a quantity of bio-oil comparable with existing industrial reactors. Bio-oil stability was measured using viscosity, water content, pH and heating value changes under specific conditions. Plant developmental characteristics were significantly different (P≤0.05) between all harvest points. The stage of crop senescence was correlated with nutrient remobilisation (N, P, K; r2=0.9043, r2=0.9920, r2=0.9977 respectively) and affected bio-oil quality. Harvest time and senescence impacted bio-oil quality and stability. For fast pyrolysis processing of Miscanthus, the harvest time of Miscanthus can be extended to cover a wider harvest window whilst still maintaining bio-oil quality but this may impact mineral depletion in, and long term sustainability of, the crop unless these minerals can be recycled. PMID:23262009

  14. A fast real time time-dependent density functional theory simulation method

    NASA Astrophysics Data System (ADS)

    Wang, Lin-Wang; Wang, Zhi; Li, Shu-Sheng

    2015-03-01

    We have developed an efficient real-time time-dependent density functional theory (TDDFT) method that can increase the effective time step from <1 attosecond in traditional methods to 0.1 0.5 femtosecond. Our algorithm, which carries out the non-adiabatic molecular dynamics TDDFT simulations, can have comparable speed to the Born-Oppenheimer (BO) ab initio molecular dynamics (MD). As an application, we simulated the process of an energetic Cl particle colliding onto a monolayer of MoSe2. Our simulations show a significant energy transfer from the kinetic energy of the Cl particle to the electronic energy of MoSe2, and the result of TDDFT is very different from that of BO MD simulations. This new algorithm will enable the use of real-time TD-DFT for many new simulations involving carrier dynamics and electron-phonon couplings. This work is supported by the Director, Office of Science, BES/MSED, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, through the Material Theory program in LBNL. Zhi Wang is supported by the China Scholarship Council.

  15. Fast Time-Varying Volume Rendering Using Time-Space Partition (TSP) Tree

    NASA Technical Reports Server (NTRS)

    Shen, Han-Wei; Chiang, Ling-Jen; Ma, Kwan-Liu

    1999-01-01

    We present a new, algorithm for rapid rendering of time-varying volumes. A new hierarchical data structure that is capable of capturing both the temporal and the spatial coherence is proposed. Conventional hierarchical data structures such as octrees are effective in characterizing the homogeneity of the field values existing in the spatial domain. However, when treating time merely as another dimension for a time-varying field, difficulties frequently arise due to the discrepancy between the field's spatial and temporal resolutions. In addition, treating spatial and temporal dimensions equally often prevents the possibility of detecting the coherence that is unique in the temporal domain. Using the proposed data structure, our algorithm can meet the following goals. First, both spatial and temporal coherence are identified and exploited for accelerating the rendering process. Second, our algorithm allows the user to supply the desired error tolerances at run time for the purpose of image-quality/rendering-speed trade-off. Third, the amount of data that are required to be loaded into main memory is reduced, and thus the I/O overhead is minimized. This low I/O overhead makes our algorithm suitable for out-of-core applications.

  16. Optical delay encoding for fast timing and detector signal multiplexing in PET

    PubMed Central

    Grant, Alexander M.; Levin, Craig S.

    2015-01-01

    Purpose: The large number of detector channels in modern positron emission tomography (PET) scanners poses a challenge in terms of readout electronics complexity. Multiplexing schemes are typically implemented to reduce the number of physical readout channels, but often result in performance degradation. Novel methods of multiplexing in PET must be developed to avoid this data degradation. The preservation of fast timing information is especially important for time-of-flight PET. Methods: A new multiplexing scheme based on encoding detector interaction events with a series of extremely fast overlapping optical pulses with precise delays is demonstrated in this work. Encoding events in this way potentially allows many detector channels to be simultaneously encoded onto a single optical fiber that is then read out by a single digitizer. A two channel silicon photomultiplier-based prototype utilizing this optical delay encoding technique along with dual threshold time-over-threshold is demonstrated. Results: The optical encoding and multiplexing prototype achieves a coincidence time resolution of 160 ps full width at half maximum (FWHM) and an energy resolution of 13.1% FWHM at 511 keV with 3 × 3 × 5 mm3 LYSO crystals. All interaction information for both detectors, including timing, energy, and channel identification, is encoded onto a single optical fiber with little degradation. Conclusions: Optical delay encoding and multiplexing technology could lead to time-of-flight PET scanners with fewer readout channels and simplified data acquisition systems. PMID:26233181

  17. Time-resolved spectroscopy using a chopper wheel as a fast shutter

    NASA Astrophysics Data System (ADS)

    Wang, Shicong; Wendt, Amy E.; Boffard, John B.; Lin, Chun C.

    2015-01-01

    Widely available, small form-factor, fiber-coupled spectrometers typically have a minimum exposure time measured in milliseconds, and thus cannot be used directly for time-resolved measurements at the microsecond level. Spectroscopy at these faster time scales is typically done with an intensified charge coupled device (CCD) system where the image intensifier acts as a "fast" electronic shutter for the slower CCD array. In this paper, we describe simple modifications to a commercially available chopper wheel system to allow it to be used as a "fast" mechanical shutter for gating a fiber-coupled spectrometer to achieve microsecond-scale time-resolved optical measurements of a periodically pulsed light source. With the chopper wheel synchronized to the pulsing of the light source, the time resolution can be set to a small fraction of the pulse period by using a chopper wheel with narrow slots separated by wide spokes. Different methods of synchronizing the chopper wheel and pulsing of the light sources are explored. The capability of the chopper wheel system is illustrated with time-resolved measurements of pulsed plasmas.

  18. Fast single photon avalanche photodiode-based time-resolved diffuse optical tomography scanner

    PubMed Central

    Mu, Ying; Niedre, Mark

    2015-01-01

    Resolution in diffuse optical tomography (DOT) is a persistent problem and is primarily limited by high degree of light scatter in biological tissue. We showed previously that the reduction in photon scatter between a source and detector pair at early time points following a laser pulse in time-resolved DOT is highly dependent on the temporal response of the instrument. To this end, we developed a new single-photon avalanche photodiode (SPAD) based time-resolved DOT scanner. This instrument uses an array of fast SPADs, a femto-second Titanium Sapphire laser and single photon counting electronics. In combination, the overall instrument temporal impulse response function width was 59 ps. In this paper, we report the design of this instrument and validate its operation in symmetrical and irregularly shaped optical phantoms of approximately small animal size. We were able to accurately reconstruct the size and position of up to 4 absorbing inclusions, with increasing image quality at earlier time windows. We attribute these results primarily to the rapid response time of our instrument. These data illustrate the potential utility of fast SPAD detectors in time-resolved DOT. PMID:26417526

  19. Development of a low-cost fast-timing microchannel plate photodetector

    NASA Astrophysics Data System (ADS)

    Xie, Junqi; Byrum, Karen; Demarteau, Marcel; May, Edward; Wagner, Robert; Walters, Dean; Wang, Jingbo; Xia, Lei; Zhao, Huyue

    2016-07-01

    We report on the design, fabrication and characterization of a prototype 6 × 6cm2 microchannel plate photodetector with precise fast-timing measurement capability. The whole assembly is made of low cost glass materials with a bialkali photocathode top window. All components are hermetically sealed in vacuum. The prototype photodetector exhibits time resolution of 65 ps and 16 ps at single-photoelectron and multi-photoelectron levels, respectively. The spatial resolution reaches 0.54 mm for multi-photoelectron measurements. The bialkali photocathode exhibits a maximum quantum efficiency exceeding 20% with a uniformity of ± 40 %.

  20. Fast Chebyshev-polynomial method for simulating the time evolution of linear dynamical systems.

    PubMed

    Loh, Y L; Taraskin, S N; Elliott, S R

    2001-05-01

    We present a fast method for simulating the time evolution of any linear dynamical system possessing eigenmodes. This method does not require an explicit calculation of the eigenvectors and eigenfrequencies, and is based on a Chebyshev polynomial expansion of the formal operator matrix solution in the eigenfrequency domain. It does not suffer from the limitations of ordinary time-integration methods, and can be made accurate to almost machine precision. Among its possible applications are harmonic classical mechanical systems, quantum diffusion, and stochastic transport theory. An example of its use is given for the problem of vibrational wave-packet propagation in a disordered lattice. PMID:11415044

  1. A Fast Pulsed Neutron Source for Time-of-Flight Detection of Nuclear Materials and Explosives

    SciTech Connect

    Krishnan, Mahadevan; Bures, Brian; James, Colt; Madden, Robert; Hennig, Wolfgang; Breus, Dimitry; Asztalos, Stephen; Sabourov, Konstantin; Lane, Stephen

    2011-12-13

    AASC has built a fast pulsed neutron source based on the Dense Plasma Focus (DPF). The more current version stores only 100 J but fires at {approx}10-50 Hz and emits {approx}10{sup 6}n/pulse at a peak current of 100 kA. Both sources emit 2.45{+-}0.1 MeV(DD) neutron pulses of {approx}25-40 ns width. Such fast, quasi-monoenergetic pulses allow time-of-flight detection of characteristic emissions from nuclear materials or high explosives. A test is described in which iron targets were placed at different distances from the point neutron source. Detectors such as Stilbene and LaBr3 were used to capture inelastically induced, 847 keV gammas from the iron target. Shielding of the source and detectors eliminated most (but not all) of the source neutrons from the detectors. Gated detection, pulse shape analysis and time-of-flight discrimination enable separation of gamma and neutron signatures and localization of the target. A Monte Carlo simulation allows evaluation of the potential of such a fast pulsed source for a field-portable detection system. The high rep-rate source occupies two 200 liter drums and uses a cooled DPF Head that is <500 cm{sup 3} in volume.

  2. Fast neutron measurements at the nELBE time-of-flight facility

    NASA Astrophysics Data System (ADS)

    Junghansa, A. R.; Beyer, R.; Grosse, E.; Hannaske, R.; Kögler, T.; Massarczyk, R.; Schwengner, R.; Wagner, A.

    2015-05-01

    The compact neutron-time-of-flight facility nELBE at the superconducting electron accelerator ELBE of Helmholtz-Zentrum Dresden-Rossendorf has been rebuilt. A new enlarged experimental hall with a flight path of up to 10 m is available for neutron time-of-flight experiments in the fast energy range from about 50 keV to 10 MeV. nELBE is intended to deliver nuclear data of fast neutron nuclear interactions e.g. for the transmutation of nuclear waste and improvement of neutron physical simulations of innovative nuclear systems. The experimental programme consists of transmission measurements of neutron total cross sections, elastic and inelastic scattering cross section measurements, and neutron induced fission cross sections. The inelastic scattering to the first few excited states in 56Fe was investigated by measuring the gamma production cross section with an HPGe detector. The neutron induced fission of 242Pu was studied using fast ionisation chambers with large homogeneous actinide deposits.

  3. FASTING IN ELECTIVE SURGICAL PATIENTS: COMPARISON AMONG THE TIME PRESCRIBED, PERFORMED AND RECOMMENDED ON PERIOPERATIVE CARE PROTOCOLS

    PubMed Central

    FRANCISCO, Saionara Cristina; BATISTA, Sandra Teixeira; PENA, Geórgia das Graças

    2015-01-01

    Background: Prolonged preoperative fasting may impair nutritional status of the patient and their recovery. In contrast, some studies show that fasting abbreviation can improve the response to trauma and decrease the length of hospital stay. Aim: Investigate whether the prescribed perioperative fasting time and practiced by patients is in compliance with current multimodal protocols and identify the main factors associated. Methods: Cross-sectional study with 65 patients undergoing elective surgery of the digestive tract or abdominal wall. We investigated the fasting time in the perioperative period, hunger and thirst reports, physical status, diabetes diagnosis, type of surgery and anesthesia. Results: The patients were between 19 and 87 years, mostly female (73.8%). The most performed procedure was cholecystectomy (47.69%) and general anesthesia the most used (89.23%). The most common approach was to start fasting from midnight for liquids and solids, and most of the patients received grade II (64.6%) to the physical state. The real fasting average time was 16 h (9.5-41.58) was higher than prescribed (11 h, 6.58 -26.75). The patients submitted to surgery in the afternoon were in more fasting time than those who did in the morning (p<0.001). The intensity of hunger and thirst increased in postoperative fasting period (p=0.010 and 0.027). The average period of postoperative fasting was 18.25 h (3.33-91.83) and only 23.07% restarted feeding on the same day. Conclusion: Patients were fasted for prolonged time, higher even than the prescribed time and intensity of the signs of discomfort such as hunger and thirst increased over time. To better recovery and the patient's well-being, it is necessary to establish a preoperative fasting abbreviation protocol. PMID:26734794

  4. Fast neutron flux analyzer with real-time digital pulse shape discrimination

    NASA Astrophysics Data System (ADS)

    Ivanova, A. A.; Zubarev, P. V.; Ivanenko, S. V.; Khilchenko, A. D.; Kotelnikov, A. I.; Polosatkin, S. V.; Puryga, E. A.; Shvyrev, V. G.; Sulyaev, Yu. S.

    2016-08-01

    Investigation of subthermonuclear plasma confinement and heating in magnetic fusion devices such as GOL-3 and GDT at the Budker Institute (Novosibirsk, Russia) requires sophisticated equipment for neutron-, gamma- diagnostics and upgrading data acquisition systems with online data processing. Measurement of fast neutron flux with stilbene scintillation detectors raised the problem of discrimination of the neutrons (n) from background cosmic particles (muons) and neutron-induced gamma rays (γ). This paper describes a fast neutron flux analyzer with real-time digital pulse-shape discrimination (DPSD) algorithm FPGA-implemented for the GOL-3 and GDT devices. This analyzer was tested and calibrated with the help of 137Cs and 252Cf radiation sources. The Figures of Merit (FOM) calculated for different energy cuts are presented.

  5. Optimal output fast feedback in two-time scale control of flexible arms

    NASA Technical Reports Server (NTRS)

    Siciliano, B.; Calise, A. J.; Jonnalagadda, V. R. P.

    1986-01-01

    Control of lightweight flexible arms moving along predefined paths can be successfully synthesized on the basis of a two-time scale approach. A model following control can be designed for the reduced order slow subsystem. The fast subsystem is a linear system in which the slow variables act as parameters. The flexible fast variables which model the deflections of the arm along the trajectory can be sensed through strain gage measurements. For full state feedback design the derivatives of the deflections need to be estimated. The main contribution of this work is the design of an output feedback controller which includes a fixed order dynamic compensator, based on a recent convergent numerical algorithm for calculating LQ optimal gains. The design procedure is tested by means of simulation results for the one link flexible arm prototype in the laboratory.

  6. Test of relativistic time dilation with fast optical atomic clocks at different velocities

    NASA Astrophysics Data System (ADS)

    Reinhardt, Sascha; Saathoff, Guido; Buhr, Henrik; Carlson, Lars A.; Wolf, Andreas; Schwalm, Dirk; Karpuk, Sergei; Novotny, Christian; Huber, Gerhard; Zimmermann, Marcus; Holzwarth, Ronald; Udem, Thomas; Hänsch, Theodor W.; Gwinner, Gerald

    2007-12-01

    Time dilation is one of the most fascinating aspects of special relativity as it abolishes the notion of absolute time. It was first observed experimentally by Ives and Stilwell in 1938 using the Doppler effect. Here we report on a method, based on fast optical atomic clocks with large, but different Lorentz boosts, that tests relativistic time dilation with unprecedented precision. The approach combines ion storage and cooling with optical frequency counting using a frequency comb. 7Li+ ions are prepared at 6.4% and 3.0% of the speed of light in a storage ring, and their time is read with an accuracy of 2×10-10 using laser saturation spectroscopy. The comparison of the Doppler shifts yields a time dilation measurement represented by a Mansouri-Sexl parameter , consistent with special relativity. This constrains the existence of a preferred cosmological reference frame and CPT- and Lorentz-violating `new' physics beyond the standard model.

  7. Fast and accurate Monte Carlo sampling of first-passage times from Wiener diffusion models

    PubMed Central

    Drugowitsch, Jan

    2016-01-01

    We present a new, fast approach for drawing boundary crossing samples from Wiener diffusion models. Diffusion models are widely applied to model choices and reaction times in two-choice decisions. Samples from these models can be used to simulate the choices and reaction times they predict. These samples, in turn, can be utilized to adjust the models’ parameters to match observed behavior from humans and other animals. Usually, such samples are drawn by simulating a stochastic differential equation in discrete time steps, which is slow and leads to biases in the reaction time estimates. Our method, instead, facilitates known expressions for first-passage time densities, which results in unbiased, exact samples and a hundred to thousand-fold speed increase in typical situations. In its most basic form it is restricted to diffusion models with symmetric boundaries and non-leaky accumulation, but our approach can be extended to also handle asymmetric boundaries or to approximate leaky accumulation. PMID:26864391

  8. Time-resolved diffuse optical tomography using fast-gated single-photon avalanche diodes

    PubMed Central

    Puszka, Agathe; Di Sieno, Laura; Mora, Alberto Dalla; Pifferi, Antonio; Contini, Davide; Boso, Gianluca; Tosi, Alberto; Hervé, Lionel; Planat-Chrétien, Anne; Koenig, Anne; Dinten, Jean-Marc

    2013-01-01

    We present the first experimental results of reflectance Diffuse Optical Tomography (DOT) performed with a fast-gated single-photon avalanche diode (SPAD) coupled to a time-correlated single-photon counting system. The Mellin-Laplace transform was employed to process time-resolved data. We compare the performances of the SPAD operated in the gated mode vs. the non-gated mode for the detection and localization of an absorbing inclusion deeply embedded in a turbid medium for 5 and 15 mm interfiber distances. We demonstrate that, for a given acquisition time, the gated mode enables the detection and better localization of deeper absorbing inclusions than the non-gated mode. These results obtained on phantoms demonstrate the efficacy of time-resolved DOT at small interfiber distances. By achieving depth sensitivity with limited acquisition times, the gated mode increases the relevance of reflectance DOT at small interfiber distance for clinical applications. PMID:24009998

  9. Fast Estimate of Rupture Process of Large Earthquakes via Real Time Hi-net Data

    NASA Astrophysics Data System (ADS)

    Wang, D.; Kawakatsu, H.; Mori, J. J.

    2014-12-01

    We developed a real time system based on Hi-net seismic array that can offer fast and reliable source information, for example, source extent and rupture velocity, for earthquakes that occur at distance of roughly 30°- 85°with respect to the array center. We perform continuous grid search on a Hi-net real time data stream to identify possible source locations (following Nishida, K., Kawakatsu, H., and S. Obara, 2008). Earthquakes that occurred off the bright area of the array (30°- 85°with respect to the array center) will be ignored. Once a large seismic event is identified successfully, back-projection will be implemented to trace the source propagation and energy radiation. Results from extended global GRiD-MT and real time W phase inversion will be combined for the better identification of large seismic events. The time required is mainly due to the travel time from the epicenter to the array stations, so we can get the results between 6 to 13 min depending on the epicenter distances. This system can offer fast and robust estimates of earthquake source information, which will be useful for disaster mitigation, such as tsunami evacuation, emergency rescue, and aftershock hazard evaluation.

  10. Modeling of Time-correlated Detection of Fast Neutrons Emitted in Induced SNM Fission

    NASA Astrophysics Data System (ADS)

    Guckes, Amber; Barzilov, Alexander; Richardson, Norman

    Neutron multiplicity methods are widely used in the assay of fissile materials. Fission reactions release multiple neutrons simultaneously. Time-correlated detection of neutrons provides a coincidence signature that is unique to fission,which enables distinguishing it from other events. In general, fission neutrons are fast. Thermal neutron sensors require the moderation of neutrons prior to a detection event; therefore, the neutron's energy and the event's timing information may be distorted, resulting in the wide time windows in the correlation analysis. Fastneutron sensing using scintillators allows shortening the time correlation window. In this study, four EJ-299-33A plastic scintillator detectors with neutron/photon pulse shape discrimination properties were modeled usingthe MCNP6 code. This sensor array was studied for time-correlated detection of fast neutrons emitted inthe induced fission of 239Pu and (α,n) neutron sources. This paper presents the results of computational modeling of arrays of these plastic scintillator sensors as well as3He detectors equipped with a moderator.

  11. Time-resolved changes in equatorial x-ray diffraction and stiffness during rise of tetanic tension in intact length-clamped single muscle fibers.

    PubMed Central

    Cecchi, G; Griffiths, P J; Bagni, M A; Ashley, C C; Maeda, Y

    1991-01-01

    We report the first time-resolved x-ray diffraction studies on tetanized intact single muscle fibers of the frog. The 10, 11, 20, 21, 30, and Z equatorial reflections were clearly resolved in the relaxed fiber. The preparation readily withstood 100 1-s duration (0.4-s beam exposure) tetani at 4 degrees C (less than 4% decline of force and no deterioration in the 10, 11 equatorial intensity ratio at rest or during activation). Equatorial intensity changes (10 and 11) and fiber stiffness led tension (t1/2 lead 20 ms at 4 degrees C) during the tetanus rise and lagged during the isometric phase of relaxation. These findings support the existence of a low force cross-bridge state during the rise of tetanic tension and isometric relaxation that is not evident at the tetanus plateau. In "fixed end" tetani lattice expansion occurred with a time course similar to stiffness during the tetanus rise. During relaxation, lattice spacing increased slightly, while the sarcomere length remained isometric, but underwent large changes after the "shoulder" of tension. Under length clamp control, lattice expansion during the tetanus rise was reduced or abolished, and compression (2%) of the lattice was observed. A lattice compression is predicted by certain cross-bridge models of force generation (Schoenberg, M. 1980. Biophys. J. 30:51-68; Schoenberg, M. 1980. Biophys. J. 30:69-78). PMID:1873464

  12. Axial Magma System Geometry beneath a Fast-Spreading Mid-Ocean Ridge: Insight from Three-Dimensional Seismic Reflection Imaging on the East Pacific Rise 9º42' to 9º57'N

    NASA Astrophysics Data System (ADS)

    Carton, H. D.; Carbotte, S. M.; Mutter, J. C.; Canales, J. P.; Nedimovic, M. R.

    2014-12-01

    The fast-spreading East Pacific Rise at the 9º50'N Ridge 2000 Integrated Study Site was the focus of the first academic 3D, multi-source, multi-streamer seismic survey, carried out aboard R/V Langseth in summer 2008. The main area of 3D coverage extends from 9º42-57'N, spanning the seafloor extent of two documented volcanic eruptions. There, the 3D geometry of the mid-crustal axial magma lens (AML), located ~1.5 km below the seafloor, was initially investigated using a best 1D stacking velocity function hung from the seafloor and two-pass post-stack time migration. Preliminary results suggested a relatively narrow (~0.5-1.8 km wide) AML showing fingering and overlap of individual magma bodies, particularly in association with several small-scale ridge-axis discontinuities identified from seafloor morphology and structure of the axial summit trough. A westward-dipping limb of the AML was imaged near 9º51'N, where the AML attains its largest width. From 9º53-56'N, the AML was seen to veer slightly westward, in accordance with a shift in orientation of the ridge. Sub-axial magma lenses (SAMLs) have been recently imaged between 9º20' and 9º56'N on along-axis reflection profiles from the same survey, with the suggestion that these deeper lenses may have contributed melts to the 2005/06 eruption. In the cross-axis dataset, SAML events are observed down to ~600-700 ms (~1.7-2 km) below the AML. They sometimes appear slightly offset with respect to the center of the AML. They are generally less bright than the AML reflection, some of them display prominent diffraction tails on un-migrated sections, and the deeper events have a distinctly lower frequency content than the shallower ones. New images for the 9º42-57'N area are currently being generated from a suite of detailed stacking velocities for the AML and SAML events and 3D post-stack time migration, which will provide insight into the width and along-axis continuity of individual magma bodies at multiple levels

  13. Characterizing a fast-response, low-afterglow liquid scintillator for neutron time-of-flight diagnostics in fast ignition experiments

    SciTech Connect

    Abe, Y. Hosoda, H.; Arikawa, Y.; Nagai, T.; Kojima, S.; Sakata, S.; Inoue, H.; Iwasa, Y.; Iwano, K.; Yamanoi, K.; Fujioka, S.; Nakai, M.; Sarukura, N.; Shiraga, H.; Norimatsu, T.; Azechi, H.

    2014-11-15

    The characteristics of oxygen-enriched liquid scintillators with very low afterglow are investigated and optimized for application to a single-hit neutron spectrometer for fast ignition experiments. It is found that 1,2,4-trimethylbenzene has better characteristics as a liquid scintillator solvent than the conventional solvent, p-xylene. In addition, a benzophenon-doped BBQ liquid scintillator is shown to demonstrate very rapid time response, and therefore has potential for further use in neutron diagnostics with fast time resolution.

  14. Who Gets a Mentor? A Longitudinal Assessment of the Rising Star Hypothesis

    ERIC Educational Resources Information Center

    Singh, Romila; Ragins, Belle Rose; Tharenou, Phyllis

    2009-01-01

    This study assessed the rising star hypothesis, which proposes that individuals who are on the fast track to career success are more likely to gain mentors than others. The study used a sample of employees who had never been mentored and examined the relationship between rising star attributes measured at Time 1 and the attainment of a mentor a…

  15. Wavelet-based fast time-resolved magnetic sensing with electronic spins in diamond

    NASA Astrophysics Data System (ADS)

    Xu, Nanyang; Jiang, Fengjian; Tian, Yu; Ye, Jianfeng; Shi, Fazhan; Lv, Haijiang; Wang, Ya; Wrachtrup, Jörg; Du, Jiangfeng

    2016-04-01

    Time-resolved magnetic sensing is of great importance from fundamental studies to applications in physical and biological sciences. Recently, the nitrogen-vacancy defect center in diamond has been developed as a promising sensor of magnetic fields under ambient conditions. However, methods to reconstruct time-resolved magnetic fields with high sensitivity are not yet fully developed. Here, we propose and demonstrate a sensing method based on spin echo and Haar wavelet transformation. Our method is exponentially faster in reconstructing time-resolved magnetic fields with comparable sensitivity than existing methods. It is also easier to implement in experiments. Furthermore, the wavelet's unique features enable our method to extract information from the whole signal with only part of the measuring sequences. We then explore this feature for a fast detection of simulated nerve impulses. These results will be useful to time-resolved magnetic sensing with quantum probes at nanoscale.

  16. Fast minimum-redundancy prefix coding for real-time space data compression

    NASA Astrophysics Data System (ADS)

    Huang, Bormin

    2007-09-01

    The minimum-redundancy prefix-free code problem is to determine an array l = {l I ,..., f n} of n integer codeword lengths, given an array f = {f I ,..., f n} of n symbol occurrence frequencies, such that the Kraft-McMillan inequality [equation] holds and the number of the total coded bits [equation] is minimized. Previous minimum-redundancy prefix-free code based on Huffman's greedy algorithm solves this problem in O (n) time if the input array f is sorted; but in O (n log n) time if f is unsorted. In this paper a fast algorithm is proposed to solve this problem in linear time if f is unsorted. It is suitable for real-time applications in satellite communication and consumer electronics. We also develop its VLSI architecture that consists of four modules, namely, the frequency table builder, the codeword length table builder, the codeword table builder, and the input-to-codeword mapper.

  17. TimepixCam: a fast optical imager with time-stamping

    NASA Astrophysics Data System (ADS)

    Fisher-Levine, M.; Nomerotski, A.

    2016-03-01

    We describe a novel fast optical imager, TimepixCam, based on an optimized silicon pixel sensor with a thin entrance window, read out by a Timepix ASIC. TimepixCam is able to record and time-stamp light flashes in excess of 1,000 photons with high quantum efficiency in the 400-1000nm wavelength range with 20ns timing resolution, corresponding to an effective rate of 50 Megaframes per second. The camera was used for imaging ions impinging on a microchannel plate followed by a phosphor screen. Possible applications include spatial and velocity map imaging of ions in time-of-flight mass spectroscopy; coincidence imaging of ions and electrons, and other time-resolved types of imaging spectroscopy.

  18. A Unified Constitutive Relationship for the Time-dependent Behavior of Fast Breeder Alloys

    NASA Technical Reports Server (NTRS)

    Robinson, D. N.

    1983-01-01

    Constitutive equations based on classical concepts of creep and plasticity generally rest on the assumption that the inelastic strain can be decomposed into two distinct and additive contributions, one time dependent (creep) and the other time dependent (plastic). It is suggested that an approach is to adopt a unified representation in which creep and plasticity are characterized as occurring simultaneously and interactively and time is an essential ingredient throughout. Examples of the inherent time dependency exhibited by some fast breeder alloys at elevated temperature are rate dependency under monotonic and cyclic straining, thermal recovery and strong creep-elasticity interaction. The stron influence of the recent history of plastic straining on stress relaxation is shown.

  19. A fast-saliency method for real-time infrared small target detection

    NASA Astrophysics Data System (ADS)

    Qi, Shengxiang; Xu, Guojing; Mou, Zhiying; Huang, Dayu; Zheng, Xueli

    2016-07-01

    Infrared small target detection plays an important role in applications including military reconnaissance, early warning and terminal guidance. In this paper, we present a fast method, called fast-saliency, with very low computational complexity, for real-time small target detection in single image frame under various complex backgrounds. Different from traditional algorithms, the proposed method is inspired by a recent research on visual saliency detection indicating that small salient signals could be well detected by a gradient enhancement operation combined with Gaussian smoothing, which is able to delineate regions of small targets in infrared images. Concisely, there are only four simple steps contained in fast-saliency. In order, they are gradient operation, square computation, Gaussian smoothing and automatic thresholding, representing the four procedures as highpass filtering, target enhancement, noise suppression and target segmentation, respectively. Especially, for the most crucial step, gradient operation, we innovatively propose a 5 × 5 facet kernel operator that holds the key for separating the small targets from backgrounds. To verify the effectiveness of our proposed method, a set of real infrared images covering typical backgrounds with sea, sky and ground clutters are tested in experiments. The results demonstrate that it outperforms the state-of-the-art methods not only in detection accuracy, but also in computation efficiency.

  20. Ciguatera Incidence in the US Virgin Islands Has Not Increased over a 30-Year Time Period Despite Rising Seawater Temperatures

    PubMed Central

    Radke, Elizabeth G.; Grattan, Lynn M.; Cook, Robert L.; Smith, Tyler B.; Anderson, Donald M.; Morris, J. Glenn

    2013-01-01

    Ciguatera fish poisoning is the most common marine food poisoning worldwide. It has been hypothesized that increasing seawater temperature will result in increasing ciguatera incidence. In St. Thomas, US Virgin Islands, we performed an island-wide telephone survey (N = 807) and a medical record review of diagnosed ciguatera cases at the emergency department of the sole hospital and compared these data with comparable data sources collected in 1980. Annual incidence from both recent data sources remained high (12 per 1,000 among adults in the telephone survey). However, the combined data sources suggest that incidence has declined by 20% or more or remained stable over 30 years, whereas seawater temperatures were increasing. Illness was associated with lower education levels, higher levels of fish consumption, and having previous episodes of ciguatera; population shifts from 1980 to 2010 in these factors could explain an incidence decline of approximately 3 per 1,000, obscuring effects from rising seawater temperature. PMID:23400575

  1. Paving the seafloor: Volcanic emplacement processes during the 2005-2006 eruptions at the fast spreading East Pacific Rise, 9°50‧N

    NASA Astrophysics Data System (ADS)

    Fundis, A. T.; Soule, S. A.; Fornari, D. J.; Perfit, M. R.

    2010-08-01

    The 2005-2006 eruptions near 9°50'N at the East Pacific Rise (EPR) marked the first observed repeat eruption at a mid-ocean ridge and provided a unique opportunity to deduce the emplacement dynamics of submarine lava flows. Since these new flows were documented in April 2006, a total of 40 deep-towed imaging surveys have been conducted with the Woods Hole Oceanographic Institution's (WHOI) TowCam system. More than 60,000 digital color images and high-resolution bathymetric profiles of the 2005-2006 flows from the TowCam surveys were analyzed for lava flow morphology and for the presence of kipukas, collapse features, faults and fissures. We use these data to quantify the spatial distributions of lava flow surface morphologies and to investigate how they relate to the physical characteristics of the ridge crest, such as seafloor slope, and inferred dynamics of flow emplacement. We conclude that lava effusion rate was the dominant factor controlling the observed morphological variations in the 2005-2006 flows. We also show that effusion rates were higher than in previously studied eruptions at this site and varied systematically along the length of the eruptive fissure. This is the first well-documented study in which variations in seafloor lava morphology can be directly related to a well documented ridge-crest eruption where effusion rate varied significantly.

  2. Fast monitoring of epileptic seizures using recurrence time statistics of electroencephalography

    PubMed Central

    Gao, Jianbo; Hu, Jing

    2013-01-01

    Epilepsy is a relatively common brain disorder which may be very debilitating. Currently, determination of epileptic seizures often involves tedious, time-consuming visual inspection of electroencephalography (EEG) data by medical experts. To better monitor seizures and make medications more effective, we propose a recurrence time based approach to characterize brain electrical activity. Recurrence times have a number of distinguished properties that make it very effective for forewarning epileptic seizures as well as studying propagation of seizures: (1) recurrence times amount to periods of periodic signals, (2) recurrence times are closely related to information dimension, Lyapunov exponent, and Kolmogorov entropy of chaotic signals, (3) recurrence times embody Shannon and Renyi entropies of random fields, and (4) recurrence times can readily detect bifurcation-like transitions in dynamical systems. In particular, property (4) dictates that unlike many other non-linear methods, recurrence time method does not require the EEG data be chaotic and/or stationary. Moreover, the method only contains a few parameters that are largely signal-independent, and hence, is very easy to use. The method is also very fast—it is fast enough to on-line process multi-channel EEG data with a typical PC. Therefore, it has the potential to be an excellent candidate for real-time monitoring of epileptic seizures in a clinical setting. PMID:24137126

  3. Hydrothermal mineral deposits and fossil biota from a young (0.1 Ma) abyssal hill on the flank of the fast spreading East Pacific Rise: Evidence for pulsed hydrothermal flow and tectonic tapping of axial heat and fluids

    NASA Astrophysics Data System (ADS)

    Benjamin, Sara B.; Haymon, Rachel M.

    2006-05-01

    Heat flow data indicate that most hydrothermal heat loss from ocean lithosphere occurs on the flanks of the mid-ocean ridge, but few ridge flank hydrothermal sites are known. We describe the first nonseamount, abyssal hill hydrothermal mineral deposits to be recovered from the fast spreading East Pacific Rise (EPR) flanks. Deposits were sampled at two sites on an abyssal hill ˜5 km east of the EPR axis, just north of Clipperton Fracture Zone at 10°20'N, on ˜0.1 Ma lithosphere. "Tevnia Site" is on the axis-facing fault scarp of the hill, and "Ochre Site" is located ˜950 m farther east near the base of the outward-facing slope. Clusters of fragile, biodegradable Tevnia worm tubes at both sites indicate that hydrothermal fluids carried sufficient H2S to sustain Tevnia worms, and that fluid flow waned too recently to allow time for tube destruction. Presence of microbial mats and other biota also are consistent with recent waning of flow. The deposits are mineralogically zoned, from nontronite-celadonite to hydrous Fe-oxide+opaline silica to Mn-oxide (birnessite and todorokite). This places them into a distinctive class of Fe-Si-Mn hydrothermal deposits found along tectonic cracks and faults in young oceanic crust, and suggests that (1) deposits precipitated along an O2 gradient between ambient seawater and hydrothermal fluid; (2) fluid temperatures were <150°C and (3) undiluted fluids were Mg-depleted, and Fe-, K-, Si- and Mn-enriched. These fluids may derive from high temperature seawater-basalt interaction ± phase separation proximal to the axial melt zone, and lose Cu and Zn before venting due to conductive cooling and/or pH increase. Ochre Site samples are purely hydrothermal; however, Tevnia Site samples incorporate volcanic, sedimentary, and fossil components, and exhibit at least three generations of fracturing and hydrothermal cementation. The Tevnia Site breccias accumulated on the exposed fault scarp, possibly during multiple slip events and

  4. Using Graphs for Fast Error Term Approximation of Time-varying Datasets

    SciTech Connect

    Nuber, C; LaMar, E C; Pascucci, V; Hamann, B; Joy, K I

    2003-02-27

    We present a method for the efficient computation and storage of approximations of error tables used for error estimation of a region between different time steps in time-varying datasets. The error between two time steps is defined as the distance between the data of these time steps. Error tables are used to look up the error between different time steps of a time-varying dataset, especially when run time error computation is expensive. However, even the generation of error tables itself can be expensive. For n time steps, the exact error look-up table (which stores the error values for all pairs of time steps in a matrix) has a memory complexity and pre-processing time complexity of O(n2), and O(1) for error retrieval. Our approximate error look-up table approach uses trees, where the leaf nodes represent original time steps, and interior nodes contain an average (or best-representative) of the children nodes. The error computed on an edge of a tree describes the distance between the two nodes on that edge. Evaluating the error between two different time steps requires traversing a path between the two leaf nodes, and accumulating the errors on the traversed edges. For n time steps, this scheme has a memory complexity and pre-processing time complexity of O(nlog(n)), a significant improvement over the exact scheme; the error retrieval complexity is O(log(n)). As we do not need to calculate all possible n2 error terms, our approach is a fast way to generate the approximation.

  5. Design and evaluation of a device for fast multispectral time-resolved fluorescence spectroscopy and imaging

    SciTech Connect

    Yankelevich, Diego R.; Ma, Dinglong; Liu, Jing; Sun, Yang; Sun, Yinghua; Bec, Julien; Marcu, Laura; Elson, Daniel S.

    2014-03-15

    The application of time-resolved fluorescence spectroscopy (TRFS) to in vivo tissue diagnosis requires a method for fast acquisition of fluorescence decay profiles in multiple spectral bands. This study focusses on development of a clinically compatible fiber-optic based multispectral TRFS (ms-TRFS) system together with validation of its accuracy and precision for fluorescence lifetime measurements. It also presents the expansion of this technique into an imaging spectroscopy method. A tandem array of dichroic beamsplitters and filters was used to record TRFS decay profiles at four distinct spectral bands where biological tissue typically presents fluorescence emission maxima, namely, 390, 452, 542, and 629 nm. Each emission channel was temporally separated by using transmission delays through 200 μm diameter multimode optical fibers of 1, 10, 19, and 28 m lengths. A Laguerre-expansion deconvolution algorithm was used to compensate for modal dispersion inherent to large diameter optical fibers and the finite bandwidth of detectors and digitizers. The system was found to be highly efficient and fast requiring a few nano-Joule of laser pulse energy and <1 ms per point measurement, respectively, for the detection of tissue autofluorescent components. Organic and biological chromophores with lifetimes that spanned a 0.8–7 ns range were used for system validation, and the measured lifetimes from the organic fluorophores deviated by less than 10% from values reported in the literature. Multi-spectral lifetime images of organic dye solutions contained in glass capillary tubes were recorded by raster scanning the single fiber probe in a 2D plane to validate the system as an imaging tool. The lifetime measurement variability was measured indicating that the system provides reproducible results with a standard deviation smaller than 50 ps. The ms-TRFS is a compact apparatus that makes possible the fast, accurate, and precise multispectral time-resolved fluorescence

  6. Real-Time Robust Tracking for Motion Blur and Fast Motion via Correlation Filters.

    PubMed

    Xu, Lingyun; Luo, Haibo; Hui, Bin; Chang, Zheng

    2016-01-01

    Visual tracking has extensive applications in intelligent monitoring and guidance systems. Among state-of-the-art tracking algorithms, Correlation Filter methods perform favorably in robustness, accuracy and speed. However, it also has shortcomings when dealing with pervasive target scale variation, motion blur and fast motion. In this paper we proposed a new real-time robust scheme based on Kernelized Correlation Filter (KCF) to significantly improve performance on motion blur and fast motion. By fusing KCF and STC trackers, our algorithm also solve the estimation of scale variation in many scenarios. We theoretically analyze the problem for CFs towards motions and utilize the point sharpness function of the target patch to evaluate the motion state of target. Then we set up an efficient scheme to handle the motion and scale variation without much time consuming. Our algorithm preserves the properties of KCF besides the ability to handle special scenarios. In the end extensive experimental results on benchmark of VOT datasets show our algorithm performs advantageously competed with the top-rank trackers. PMID:27618046

  7. Time-resolved Fast Neutron Radiography of Air-water Two-phase Flows

    NASA Astrophysics Data System (ADS)

    Zboray, Robert; Dangendorf, Volker; Mor, Ilan; Tittelmeier, Kai; Bromberger, Benjamin; Prasser, Horst-Michael

    Neutron imaging, in general, is a useful technique for visualizing low-Z materials (such as water or plastics) obscured by high-Z materials. However, when significant amounts of both materials are present and full-bodied samples have to be examined, cold and thermal neutrons rapidly reach their applicability limit as the samples become opaque. In such cases one can benefit from the high penetrating power of fast neutrons. In this work we demonstrate the feasibility of time-resolved, fast neutron radiography of generic air-water two-phase flows in a 1.5 cm thick flow channel with Aluminum walls and rectangular cross section. The experiments have been carried out at the high-intensity, white-beam facility of the Physikalisch-Technische Bundesanstalt, Germany. Exposure times down to 3.33 ms have been achieved at reasonable image quality and acceptable motion artifacts. Different two-phase flow regimes such as bubbly slug and churn flows have been examined. Two-phase flow parameters like the volumetric gas fraction, bubble size and bubble velocities have been measured.

  8. Comparisons of Crosswind Velocity Profile Estimates Used in Fast-Time Wake Vortex Prediction Models

    NASA Technical Reports Server (NTRS)

    Pruis, Mathew J.; Delisi, Donald P.; Ahmad, Nashat N.

    2011-01-01

    Five methods for estimating crosswind profiles used in fast-time wake vortex prediction models are compared in this study. Previous investigations have shown that temporal and spatial variations in the crosswind vertical profile have a large impact on the transport and time evolution of the trailing vortex pair. The most important crosswind parameters are the magnitude of the crosswind and the gradient in the crosswind shear. It is known that pulsed and continuous wave lidar measurements can provide good estimates of the wind profile in the vicinity of airports. In this study comparisons are made between estimates of the crosswind profiles from a priori information on the trajectory of the vortex pair as well as crosswind profiles derived from different sensors and a regional numerical weather prediction model.

  9. Finite Time Extinction for Stochastic Sign Fast Diffusion and Self-Organized Criticality

    NASA Astrophysics Data System (ADS)

    Gess, Benjamin

    2015-04-01

    We prove finite time extinction for stochastic sign fast diffusion equations driven by linear multiplicative space-time noise, corresponding to the Bak-Tang-Wiesenfeld model for self-organized criticality. This solves a problem posed and left open in several works: (Barbu, Methods Appl Sci 36:1726-1733, 2013; Röckner and Wang, J Lond Math Soc (2) 87:545-560, 2013; Barbu et al. J Math Anal Appl 389:147-164, 2012; Barbu and Röckner, Comm Math Phys 311:539-555, 2012; Barbu et al., Comm Math Phys 285:901-923, 2009, C R Math Acad Sci Paris 347(1-2):81-84, 2009). The highly singular-degenerate nature of the drift in interplay with the stochastic perturbation causes the need for new methods in the analysis of mass diffusion, and several new estimates and techniques are introduced.

  10. A laser diode based system for calibration of fast time-of-flight detectors

    NASA Astrophysics Data System (ADS)

    Bertoni, R.; Bonesini, M.; de Bari, A.; Rossella, M.

    2016-05-01

    A system based on commercially available items, such as a laser diode, emitting in the visible range ~ 400 nm, and multimode fiber patches, fused fiber splitters and optical switches may be assembled, for time calibration of multi-channels time-of-flight (TOF) detectors with photomultipliers' (PMTs') readout. As available laser diode sources have unfortunately limited peak power, the main experimental problem is the tight light power budget of such a system. In addition, while the technology for fused fiber splitters is common in the Telecom wavelength range (λ ~ 850, 1300–1500 nm), it is not easily available in the visible one. Therefore, extensive laboratory tests had to be done on purpose, to qualify the used optical components, and a full scale timing calibration prototype was built. Obtained results show that with such a system, a calibration resolution (σ) in the range 20–30 ps may be within reach. Therefore, fast multi-channels TOF detectors, with timing resolutions in the range 50–100 ps, may be easily calibrated in time. Results on tested optical components may be of interest also for time calibration of different light detection systems based on PMTs, as the ones used for detection of the vacuum ultraviolet scintillation light emitted by ionizing particles in large LAr TPCs.

  11. Differential time course of liver and kidney glucose-6 phosphatase activity during long-term fasting in rat correlates with differential time course of messenger RNA level.

    PubMed

    Minassian, C; Zitoun, C; Mithieux, G

    1996-02-01

    We have studied the role of Glc6Pase mRNA abundance in the time course of Glc6Pase activity in liver and kidney during long-term fasting in rat. Refered to the mRNA level in the fed state, Glc6Pase mRNA abundance was increased by 3.5 +/- 0.5 and 3.7 +/- 0.5 times (mean +/- S.E.M., n = 5) in the 24 h and 48 h-fasted liver, respectively. Then, the liver Glc6Pase mRNA was decreased to the level of the fed liver after 72 and 96 h of fasting (1.0 +/- 0.3 and 1.4 +/- 0.3). In the kidney, Glc6Pase mRNA abundance was increased by 2.7 +/- 1.0 and 5 +/- 1.2 times at 24 and 48 h of fasting, respectively. Then, it plateaued at the level of the 48 h fasted kidney after 72 h and 96 h of fasting (4.5 +/- 1.0 and 4.3 +/- 1.0). After 24 and 48 h-refeeding, the abundance of Glc6Pase mRNA in 48 h-fasted rats was decreased to the level found in the liver and kidney of fed rats. The time course of the activity of Glc6Pase catalytic subunit during fasting and refeeding was strikingly parallel to the time course of Glc6Pase mRNA level in respective tissues. These data strongly suggest that the differential expression of Glc6Pase activity in liver and kidney in the course of fasting may be accounted for by the respective time course of mRNA abundance in both organs. PMID:8717437

  12. Effects of Ramadan on physical capacities of North African boys fasting for the first time

    PubMed Central

    Fenneni, Mohamed A.; Latiri, Imed; Aloui, Asma; Rouatbi, Sonia; Saafi, Mohamed A.; Bougmiza, Iheb; Chamari, Karim; Saad, Helmi Ben

    2014-01-01

    Introduction Most of the literature related to the effects of Ramadan fasting on physical performance has focused on adults, and only three studies have examined its impact on children’s physical performance. Aims To examine the effects of Ramadan fasting on first-time fasting boys’ performance in short-term explosive exercises [vertical and horizontal jump tests (VJT and HJT), 20-m and 30-m sprints and medicine-ball throw (MBT)], as well as in sub-maximal endurance [6-min walking distance (6MWD) measured during the 6-min walk test (6MWT)]. Methods Eighteen Tunisian boys [mean±standard deviation (SD) of age and body mass (BM): 11.9±0.8 y and 55.4±18.2 kg, respectively] were included. The experimental design comprised four testing phases: 2-weeks before Ramadan (BR), the end of the second week (R2) and the fourth week (R4) of Ramadan, and 10–12 days after the end of Ramadan (AR). At each phase, boys performed two test sessions in the afternoon (15:00–17:00 h) interrupted by 48 h of recovery (first test session: BM, VJT, HJT, and 20-m and 30-m sprint tests; second session: MBT and 6MWT). The study was conducted during the summer of 2012 from July 5 to August 29. Results 6MWDs (m) were significantly shorter during R2 (652±101) and R4 (595±123) compared to BR (697±86) and came back to baseline values AR. BM (kg) mean±SD did not significantly change during R2 (52±15) and during R4 (53±15) compared to BR (55±17), and short-term explosive performances were unchanged throughout the study. Conclusion In non-athletic children, first-ever Ramadan fasting impairs sub-maximal aerobic capacity but has no effect on BM or short-term explosive performance. PMID:25261691

  13. Automatic Adaptation to Fast Input Changes in a Time-Invariant Neural Circuit.

    PubMed

    Bharioke, Arjun; Chklovskii, Dmitri B

    2015-08-01

    Neurons must faithfully encode signals that can vary over many orders of magnitude despite having only limited dynamic ranges. For a correlated signal, this dynamic range constraint can be relieved by subtracting away components of the signal that can be predicted from the past, a strategy known as predictive coding, that relies on learning the input statistics. However, the statistics of input natural signals can also vary over very short time scales e.g., following saccades across a visual scene. To maintain a reduced transmission cost to signals with rapidly varying statistics, neuronal circuits implementing predictive coding must also rapidly adapt their properties. Experimentally, in different sensory modalities, sensory neurons have shown such adaptations within 100 ms of an input change. Here, we show first that linear neurons connected in a feedback inhibitory circuit can implement predictive coding. We then show that adding a rectification nonlinearity to such a feedback inhibitory circuit allows it to automatically adapt and approximate the performance of an optimal linear predictive coding network, over a wide range of inputs, while keeping its underlying temporal and synaptic properties unchanged. We demonstrate that the resulting changes to the linearized temporal filters of this nonlinear network match the fast adaptations observed experimentally in different sensory modalities, in different vertebrate species. Therefore, the nonlinear feedback inhibitory network can provide automatic adaptation to fast varying signals, maintaining the dynamic range necessary for accurate neuronal transmission of natural inputs. PMID:26247884

  14. Temporal Gillespie Algorithm: Fast Simulation of Contagion Processes on Time-Varying Networks

    PubMed Central

    Vestergaard, Christian L.; Génois, Mathieu

    2015-01-01

    Stochastic simulations are one of the cornerstones of the analysis of dynamical processes on complex networks, and are often the only accessible way to explore their behavior. The development of fast algorithms is paramount to allow large-scale simulations. The Gillespie algorithm can be used for fast simulation of stochastic processes, and variants of it have been applied to simulate dynamical processes on static networks. However, its adaptation to temporal networks remains non-trivial. We here present a temporal Gillespie algorithm that solves this problem. Our method is applicable to general Poisson (constant-rate) processes on temporal networks, stochastically exact, and up to multiple orders of magnitude faster than traditional simulation schemes based on rejection sampling. We also show how it can be extended to simulate non-Markovian processes. The algorithm is easily applicable in practice, and as an illustration we detail how to simulate both Poissonian and non-Markovian models of epidemic spreading. Namely, we provide pseudocode and its implementation in C++ for simulating the paradigmatic Susceptible-Infected-Susceptible and Susceptible-Infected-Recovered models and a Susceptible-Infected-Recovered model with non-constant recovery rates. For empirical networks, the temporal Gillespie algorithm is here typically from 10 to 100 times faster than rejection sampling. PMID:26517860

  15. A Fast Density-Based Clustering Algorithm for Real-Time Internet of Things Stream

    PubMed Central

    Ying Wah, Teh

    2014-01-01

    Data streams are continuously generated over time from Internet of Things (IoT) devices. The faster all of this data is analyzed, its hidden trends and patterns discovered, and new strategies created, the faster action can be taken, creating greater value for organizations. Density-based method is a prominent class in clustering data streams. It has the ability to detect arbitrary shape clusters, to handle outlier, and it does not need the number of clusters in advance. Therefore, density-based clustering algorithm is a proper choice for clustering IoT streams. Recently, several density-based algorithms have been proposed for clustering data streams. However, density-based clustering in limited time is still a challenging issue. In this paper, we propose a density-based clustering algorithm for IoT streams. The method has fast processing time to be applicable in real-time application of IoT devices. Experimental results show that the proposed approach obtains high quality results with low computation time on real and synthetic datasets. PMID:25110753

  16. A fast density-based clustering algorithm for real-time Internet of Things stream.

    PubMed

    Amini, Amineh; Saboohi, Hadi; Wah, Teh Ying; Herawan, Tutut

    2014-01-01

    Data streams are continuously generated over time from Internet of Things (IoT) devices. The faster all of this data is analyzed, its hidden trends and patterns discovered, and new strategies created, the faster action can be taken, creating greater value for organizations. Density-based method is a prominent class in clustering data streams. It has the ability to detect arbitrary shape clusters, to handle outlier, and it does not need the number of clusters in advance. Therefore, density-based clustering algorithm is a proper choice for clustering IoT streams. Recently, several density-based algorithms have been proposed for clustering data streams. However, density-based clustering in limited time is still a challenging issue. In this paper, we propose a density-based clustering algorithm for IoT streams. The method has fast processing time to be applicable in real-time application of IoT devices. Experimental results show that the proposed approach obtains high quality results with low computation time on real and synthetic datasets. PMID:25110753

  17. Ultra-high throughput real-time instruments for capturing fast signals and rare events

    NASA Astrophysics Data System (ADS)

    Buckley, Brandon Walter

    Wide-band signals play important roles in the most exciting areas of science, engineering, and medicine. To keep up with the demands of exploding internet traffic, modern data centers and communication networks are employing increasingly faster data rates. Wide-band techniques such as pulsed radar jamming and spread spectrum frequency hopping are used on the battlefield to wrestle control of the electromagnetic spectrum. Neurons communicate with each other using transient action potentials that last for only milliseconds at a time. And in the search for rare cells, biologists flow large populations of cells single file down microfluidic channels, interrogating them one-by-one, tens of thousands of times per second. Studying and enabling such high-speed phenomena pose enormous technical challenges. For one, parasitic capacitance inherent in analog electrical components limits their response time. Additionally, converting these fast analog signals to the digital domain requires enormous sampling speeds, which can lead to significant jitter and distortion. State-of-the-art imaging technologies, essential for studying biological dynamics and cells in flow, are limited in speed and sensitivity by finite charge transfer and read rates, and by the small numbers of photo-electrons accumulated in short integration times. And finally, ultra-high throughput real-time digital processing is required at the backend to analyze the streaming data. In this thesis, I discuss my work in developing real-time instruments, employing ultrafast optical techniques, which overcome some of these obstacles. In particular, I use broadband dispersive optics to slow down fast signals to speeds accessible to high-bit depth digitizers and signal processors. I also apply telecommunication multiplexing techniques to boost the speeds of confocal fluorescence microscopy. The photonic time stretcher (TiSER) uses dispersive Fourier transformation to slow down analog signals before digitization and

  18. The timing of control signals underlying fast point-to-point arm movements.

    PubMed

    Ghafouri, M; Feldman, A G

    2001-04-01

    on the handle, or computed with equations of motion. In some trials, an electromagnetic brake prevented movements. In such movements, the hand force and joint torques reached a steady state after a time that was much smaller than the movement duration in unobstructed movements and was approximately equal to the time to peak velocity (mean difference < 80 ms). In an additional experiment, subjects were instructed to rapidly initiate corrections of the pushing force in response to movement arrest. They were able to initiate such corrections only when the joint torques and the pushing force had practically reached a steady state. The latency of correction onset was, however, smaller than the duration of unobstructed movements. We concluded that during the time at which the steady state torques were reached, the control pattern of IC shifts remained the same despite the movement block. Thereby the duration of these shifts did not exceed the time of reaching the steady state torques. Our findings are consistent with the hypothesis that, in unobstructed movements, the IC shifts and resulting shifts in the EP end approximately at peak velocity. In other words, during the latter part of the movement, the control signals responsible for the equilibrium shift remained constant, and the movement was driven by the arm inertial, viscous and elastic forces produced by the muscle-reflex system. Fast movements may thus be completed without continuous control guidance. As a consequence, central corrections and sequential commands may be issued rapidly, without waiting for the end of kinematic responses to each command, which may be important for many motor behaviours including typing, piano playing and speech. Our study also illustrates that the timing of the control signals may be substantially different from that of the resulting motor output and that the same control pattern may produce different motor outputs depending on external conditions. PMID:11355386

  19. [Fast and accurate extraction of ring-down time in cavity ring-down spectroscopy].

    PubMed

    Wang, Dan; Hu, Ren-Zhi; Xie, Pin-Hua; Qin, Min; Ling, Liu-Yi; Duan, Jun

    2014-10-01

    Research is conducted to accurate and efficient algorithms for extracting ring-down time (r) in cavity ring-down spectroscopy (CRDS) which is used to measure NO3 radical in the atmosphere. Fast and accurate extraction of ring-down time guarantees more precise and higher speed of measurement. In this research, five kinds of commonly used algorithms are selected to extract ring-down time which respectively are fast Fourier transform (FFT) algorithm, discrete Fourier transform (DFT) algorithm, linear regression of the sum (LRS) algorithm, Levenberg-Marquardt (LM) algorithm and least squares (LS) algorithm. Simulated ring-down signals with various amplitude levels of white noises are fitted by using five kinds of the above-mentioned algorithms, and comparison and analysis is conducted to the fitting results of five kinds of algorithms from four respects: the vulnerability to noises, the accuracy and precision of the fitting, the speed of the fitting and preferable fitting ring-down signal waveform length The research results show that Levenberg-Marquardt algorithm and linear regression of the sum algorithm are able to provide more precise results and prove to have higher noises immunity, and by comparison, the fitting speed of Leven- berg-Marquardt algorithm turns out to be slower. In addition, by analysis of simulated ring-down signals, five to ten times of ring-down time is selected to be the best fitting waveform length because in this case, standard deviation of fitting results of five kinds of algorithms proves to be the minimum. External modulation diode laser and cavity which consists of two high reflectivity mirrors are used to construct a cavity ring-down spectroscopy detection system. According to our experimental conditions, in which the noise level is 0.2%, linear regression of the sum algorithm and Levenberg-Marquardt algorithm are selected to process experimental data. The experimental results show that the accuracy and precision of linear regression of

  20. Evaluation of Fast-Time Wake Models Using Denver 2006 Field Experiment Data

    NASA Technical Reports Server (NTRS)

    Ahmad, Nash’at N.; Pruis, Matthew J.

    2015-01-01

    The National Aeronautics and Space Administration conducted a series of wake vortex field experiments at Denver in 2003, 2005, and 2006. This paper describes the lidar wake vortex measurements and associated meteorological data collected during the 2006 deployment, and includes results of recent reprocessing of the lidar data using a new wake vortex algorithm and estimates of the atmospheric turbulence using a new algorithm to estimate eddy dissipation rate from the lidar data. The configuration and set-up of the 2006 field experiment allowed out-of-ground effect vortices to be tracked in lateral transport further than any previous campaign and thereby provides an opportunity to study long-lived wake vortices in moderate to low crosswinds. An evaluation of NASA's fast-time wake vortex transport and decay models using the dataset shows similar performance as previous studies using other field data.

  1. Fast state estimation subject to random data loss in discrete-time nonlinear stochastic systems

    NASA Astrophysics Data System (ADS)

    Mahdi Alavi, S. M.; Saif, Mehrdad

    2013-12-01

    This paper focuses on the design of the standard observer in discrete-time nonlinear stochastic systems subject to random data loss. By the assumption that the system response is incrementally bounded, two sufficient conditions are subsequently derived that guarantee exponential mean-square stability and fast convergence of the estimation error for the problem at hand. An efficient algorithm is also presented to obtain the observer gain. Finally, the proposed methodology is employed for monitoring the Continuous Stirred Tank Reactor (CSTR) via a wireless communication network. The effectiveness of the designed observer is extensively assessed by using an experimental tested-bed that has been fabricated for performance evaluation of the over wireless-network estimation techniques under realistic radio channel conditions.

  2. 7Li-induced reactions for fast-timing with LaBr3:Ce detectors

    NASA Astrophysics Data System (ADS)

    Mason, P. J. R.; Podolyàk, Zs.; Mǎrginean, N.; Regan, P. H.; Alexander, T.; Algora, A.; Alharbi, T.; Bowry, M.; Britton, R.; Bucurescu, D.; Bruce, A. M.; Bunce, M.; Cǎta-Danil, G.; Cǎta-Danil, I.; Cooper, N.; Deleanu, D.; Delion, D.; Filipescu, D.; Gelletly, W.; Glodariu, T.; Gheorghe, I.; Ghiťǎ, D.; Ilie, G.; Ivanova, D.; Kisyov, S.; Lalkovski, S.; Lica, R.; Liddick, S. N.; Mǎrginean, R.; Mihai, C.; Mulholland, K.; Negret, A.; Nita, C. R.; Rice, S.; Roberts, O. J.; Sava, T.; Smith, J. F.; Söderström, P.-A.; Stevenson, P. D.; Stroe, L.; Toma, S.; Townsley, C.; Werner, V.; Wilson, E.; Wood, R. T.; Zamfir, N. V.; Zhekova, M.

    2012-10-01

    7Li induced-reactions have been used with a 186W target to populate nuclei around A˜180-190 at the National Institute of Physics and Nuclear Engineering in Bucharest, Romania. An array of high-purity germanium (HPGe) and cerium-doped lanthanum bromide (LaBr3:Ce) detectors have been used to measure sub-nanosecond half-lives with fast-timing techniques. The yrast 2+ state in 190Os was measured to be t1/2 = 375(20)ps, in excellent agreement with the literature value. The previously unreported half-life of the 564-keV state in 189Ir has also been measured and a value of t1/2 = 540(100)ps ps obtained.

  3. Program for the analysis of time series. [by means of fast Fourier transform algorithm

    NASA Technical Reports Server (NTRS)

    Brown, T. J.; Brown, C. G.; Hardin, J. C.

    1974-01-01

    A digital computer program for the Fourier analysis of discrete time data is described. The program was designed to handle multiple channels of digitized data on general purpose computer systems. It is written, primarily, in a version of FORTRAN 2 currently in use on CDC 6000 series computers. Some small portions are written in CDC COMPASS, an assembler level code. However, functional descriptions of these portions are provided so that the program may be adapted for use on any facility possessing a FORTRAN compiler and random-access capability. Properly formatted digital data are windowed and analyzed by means of a fast Fourier transform algorithm to generate the following functions: (1) auto and/or cross power spectra, (2) autocorrelations and/or cross correlations, (3) Fourier coefficients, (4) coherence functions, (5) transfer functions, and (6) histograms.

  4. Extended Time as a Testing Accommodation for Students with Reading Disabilities: Does a Rising Tide Lift All Ships?

    ERIC Educational Resources Information Center

    Lewandowski, Lawrence J.; Lovett, Benjamin J.; Rogers, Cynthia L.

    2008-01-01

    Testing accommodations have become a common component of services for students with disabilities at all levels of education. This study examined the effect of a common testing accommodation--extended time--on the reading comprehension test performance of high school students. Sixty-four students, half of whom had learning disabilities (LDs) in the…

  5. "Their Rising Voices": A Study of Civil Rights, Social Movements, and Advertising in the "New York Times."

    ERIC Educational Resources Information Center

    Ross, Susan Dente

    1998-01-01

    Contributes to scholarship on social movements, the strategic use of advertising, and journalism by documenting strategic use of advertising in the "New York Times" by the civil rights movement between 1955 and 1961. Finds that the ads framed the civil rights movement to prime the audience to receive radical messages from marginalized speakers.…

  6. Multi-purpose fast neutron spectrum analyzer with real-time signal processing

    NASA Astrophysics Data System (ADS)

    Sulyaev, Yu. S.; Puryga, E. A.; Khilchenko, A. D.; Kvashnin, A. N.; Polosatkin, S. V.; Rovenskikh, A. F.; Burdakov, A. V.; Grishnyaev, E. V.

    2013-08-01

    Diagnostics of hot ion component of plasma on the products of fusion reactions is widely used on thermonuclear facilities. In case of employment of neutron spectrometers, based on organics scintillators, there is advanced technique developed to eliminate neutron pulses from gamma background—digital pulse shape discrimination. For every DPSD application it is necessary to use the fast (2-5 ns) and precise (12 bit) transient ADC unit with large amount of onboard memory for storing every digitized scintillation pulses during shot time. At present time the duration of hot thermonuclear plasma burning in large tokamaks approximate to 1 min, and this requires very high onboard memory capacity (˜100 GB). This paper describes a neutron spectrum analyzer with real-time DPSD algorithm, implemented to ADC unit. This approach saves about two orders of onboard memory capacity, gives the possibility of instant use of outcome to feedback systems. This analyzer was tested and calibrated with help of 60Co and 252Cf radiation sources, and deuterium neutron generator.

  7. Size-selective sorting in bubble streaming flows: Particle migration on fast time scales

    NASA Astrophysics Data System (ADS)

    Thameem, Raqeeb; Rallabandi, Bhargav; Hilgenfeldt, Sascha

    2015-11-01

    Steady streaming from ultrasonically driven microbubbles is an increasingly popular technique in microfluidics because such devices are easily manufactured and generate powerful and highly controllable flows. Combining streaming and Poiseuille transport flows allows for passive size-sensitive sorting at particle sizes and selectivities much smaller than the bubble radius. The crucial particle deflection and separation takes place over very small times (milliseconds) and length scales (20-30 microns) and can be rationalized using a simplified geometric mechanism. A quantitative theoretical description is achieved through the application of recent results on three-dimensional streaming flow field contributions. To develop a more fundamental understanding of the particle dynamics, we use high-speed photography of trajectories in polydisperse particle suspensions, recording the particle motion on the time scale of the bubble oscillation. Our data reveal the dependence of particle displacement on driving phase, particle size, oscillatory flow speed, and streaming speed. With this information, the effective repulsive force exerted by the bubble on the particle can be quantified, showing for the first time how fast, selective particle migration is effected in a streaming flow. We acknowledge support by the National Science Foundation under grant number CBET-1236141.

  8. Toward fast feature adaptation and localization for real-time face recognition systems

    NASA Astrophysics Data System (ADS)

    Zuo, Fei; de With, Peter H.

    2003-06-01

    In a home environment, video surveillance employing face detection and recognition is attractive for new applications. Facial feature (e.g. eyes and mouth) localization in the face is an essential task for face recognition because it constitutes an indispensable step for face geometry normalization. This paper presents a new and efficient feature localization approach for real-time personal surveillance applications with low-quality images. The proposed approach consists of three major steps: (1) self-adaptive iris tracing, which is preceded by a trace-point selection process with multiple initializations to overcome the local convergence problem, (2) eye structure verification using an eye template with limited deformation freedom, and (3) eye-pair selection based on a combination of metrics. We have tested our facial feature localization method on about 100 randomly selected face images from the AR database and 30 face images downloaded from the Internet. The results show that our approach achieves a correct detection rate of 96%. Since our eye-selection technique does not involve time-consuming deformation processes, it yields relatively fast processing. The proposed algorithm has been successfully applied to a real-time home video surveillance system and proven to be an effective and computationally efficient face normalization method preceding the face recognition.

  9. Study of the effect of current rise time on the formation of the precursor column in cylindrical wire array Z pinches at 1 MA

    SciTech Connect

    Bott, S. C.; Haas, D. M.; Eshaq, Y.; Ueda, U.; Beg, F. N.; Hammer, D. A.; Kusse, B.; Greenly, J.; Shelkovenko, T. A.; Pikuz, S. A.; Blesener, I. C.; McBride, R. D.; Douglass, J. D.; Bell, K.; Knapp, P.; Chittenden, J. P.; Lebedev, S. V.; Bland, S. N.; Hall, G. N.; Suzuki Vidal, F. A.

    2009-07-15

    The limited understanding of the mechanisms driving the mass ablation rate of cylindrical wires arrays is presently one of the major limitations in predicting array performance at the higher current levels required for inertial confinement fusion (ICF) ignition. Continued investigation of this phenomenon is crucial to realize the considerable potential for wire arrays to drive both ICF and inertial fusion energy, by enabling a predictive capability in computational modeling. We present the first study to directly compare the mass ablation rates of wire arrays as a function of the current rise rate. Formation of the precursor column is investigated on both the MAPGIE (1 MA, 250ns [Mitchell et al., Rev. Sci. Instrum. 67, 1533 (1996)]) and COBRA (1 MA, 100ns [Greenly et al., Rev. Sci. Instrum. 79, 073501 (2008)]) generators, and results are used to infer the change in the effective ablation velocity induced by the rise rate of the drive current. Laser shadowography, gated extreme ultraviolet (XUV) imaging, and x-ray diodes are used to compare the dynamical behavior on the two generators, and X-pinch radiography and XUV spectroscopy provide density evolution and temperature measurements respectively. Results are compared to predictions from an analytical scaling model developed previously from MAGPIE data, based on a fixed ablation velocity. For COBRA the column formation time occurs at 116{+-}5 ns and for Al arrays and 146{+-}5 ns for W arrays, with Al column temperature in the range of 70-165 eV. These values lie close to model predictions, inferring only a small change in the ablation velocity is induced by the factor of 2.5 change in current rise time. Estimations suggest the effective ablation velocities for MAGPIE and COBRA experiments vary by a maximum of 30%.

  10. A Fast-Time Study of Aircraft Reordering in Arrival Sequencing and Scheduling

    NASA Technical Reports Server (NTRS)

    Carr, Greg; Neuman, Frank; Tobias, Leonard (Technical Monitor)

    1998-01-01

    on estimated times of arrival, it does not take into account individual airline priorities among incoming flights. NASA is exploring the possibility of allowing airlines to express relative arrival priorities to air traffic management through the development of new CTAS scheduling algorithms which take into consideration airline arrival preferences. The accommodation of airline priorities in arrival sequencing and scheduling would under most circumstances result in a deviation from a "natural" or FCFS arrival order. As a First step toward developing airline influenced sequencing algorithms, an investigation was conducted to determine the feasibility of reordering arrival traffic from a strict FCFS sequence. A fast-time simulation has been developed which allows statistical evaluation of sequencing and scheduling algorithms for arrival traffic at the Dallas/Fort Worth Airport. In contrast to real-time simulation or field tests, which would require on the order of ninety minutes to examine a single traffic rush period, the fast-time simulation allows examination of multiple rush periods in a matter of seconds.

  11. Effect of /sup 235/U concentration on fast neutron space and time eigenvalues and eigenfunctions in uranium

    SciTech Connect

    Mohan, R.; Ahmed, F.; Kothari, L.S.

    1985-05-01

    The results of a detailed study of a fast neutron diffusion length and pulsed problem in depleted and enriched subcritical uranium assemblies (0.2 to 4% /sup 235/U) are reported. The multigroup space- and time-dependent equations are solved using the eigenfunction expansion method. The effect of /sup 235/U concentration on space (diffusion length problem) and time (pulsed problem) eigenvalues and eigenfunctions, particularly on the ''discrete'' eigenvalue and eigenfunction, is discussed. The approach to equilibrium (both in space and in time) of fast neutrons changes with changing /sup 235/U concentration.

  12. Rising College Costs.

    ERIC Educational Resources Information Center

    USA Today, 1981

    1981-01-01

    Focuses on ways in which parents of school-age children can offset the rising costs of college, including encouraging students to get summer and part-time jobs, putting savings toward students' education in accounts in students' names to save taxes, investigating cooperative work/education plans, and investing in mutual funds. (DB)

  13. Circinus X-1 revisited: Fast-timing properties in relation to spectral state

    NASA Technical Reports Server (NTRS)

    Oosterbroek, T.; Van Der Klis, M.; Kuulkers, E.; Van Paradijs, J.; Lewin, W. H. G.

    1995-01-01

    We have studied the X-ray spectral and fast-timing variations of Cir X-1 by performing a homogenous analysis of all EXOSAT ME data on this source using X-ray hardness-intensity diagrams (HIDs), color-color diagrams (CDs), and power spectra. Cir X-1 exhibits a wide range of power spectral shapes and a large variety in X-ray spectral shapes. At different epochs the power spectra variously resemble those of an atoll source, a Z source, a black-hole candidate, or are unlike any of these. At some epochs one-dimensional connected-branch patterns are seen in HID and CD, and at other times more complex structures are found. We interpret the complex behavior of Cir X-1 in terms of a model where accretion rate, orbital phase and epoch are the main determinants of the source behavior, and where the unique properties of the source are due to two special circumstances: (1) the source is the only known atoll source (accreting neutron star with a very low magnetic field) that can reach the Eddington critical accretion rate, and (2) it has a unique, highly eccentric and probably precessing orbit. Property (1) makes Cir X-1 a very important source for our understanding of the similarities in the observable properties of neutron stars and black holes as it allows to separate out black hole signatures from properties that are merely due to the presence of accretion compact with a low magnetic field.

  14. Identification of complex scattered signals with a fast real-time hybrid electro-optical correlator

    NASA Astrophysics Data System (ADS)

    Majumdar, Arun K.; Sandomirsky, Sergey

    1997-10-01

    The goal of this work was to develop a fast optical correlator for automatic real-time target recognition. The tremendous importance of optical correlators for military and civilian applications was recognized recently and approved by a US conference committee of senators nd representatives. This publication presents the experimental results of detecting and identifying complex scattered signals by using an innovative, hybrid electro-optical correlator. Our technique is based on achieving optical correlation by utilizing state-of-the-art devices: time delay integration, charge coupled devices, liquid crystal displays, and electronically controllable light sources. Results of the experiment with our optical correlator, performed with simulated sonar signals with a center frequency of 100 kHz and duration of 8 to 512 pulses, show the possibility of recognizing a Doppler shift of 20 Hz. This Doppler shift corresponds to a target velocity of 20.7 m/sec. Simulation results indicate that we can achieve significant correlation for a noisy signal by using appropriate signal length. Our experiments demonstrate that we can perform approximately 1010 multiply accumulate operations per second with the high parallel optical corrector, compared to approximately 106 multiply accumulate operations per second using a Pentium 133 MHz personal computer. This new optical correlation scheme can provide solutions for overcoming the inherent shortcomings attributable to the low dynamic range of CCD, and the problem of compatibility caused by different pixel patterns between LCD and CCD by making use of high-quality optics and modern means of achieving uniform illumination.

  15. Time-of-flight measurement of fast neutrons with Timepix detectors

    NASA Astrophysics Data System (ADS)

    Bergmann, B.; Nelson, R. O.; O'Donnell, J. M.; Pospisil, S.; Solc, J.; Takai, H.; Vykydal, Z.

    2014-05-01

    Timepix pixel detectors have been used to study the response of silicon hybrid pixel detectors to fast neutrons from a pulsed neutron beam at WNR FP30R, a 14 m long flight path, in the Los Alamos Neutron Science Center. Neutrons with kinetic energies up to 600 MeV were available. In order to enhance the conversion of neutrons to energetic charged particles, several converter foils and filters were attached to the 300 μm thick silicon sensor, i.e. polyethylene, polyethylene with aluminum, 6LiF, 6LiF with aluminum, aluminum. The Time-of-Arrival mode of the Timepix detectors has permitted the application of the Time-of-Flight (TOF) technique for the assignment of the detected interactions in the form of clusters (groups of adjacent pixels) in the pixel matrix, to the kinetic energies of the incident neutrons. It was found that, for lower neutron energies ( ~ MeV range) the cluster rates below the polyethylene and the polyethylene and aluminum region, produced by recoil protons, are a good measure for the mean kinetic energies of neutrons. For energies above 50 MeV nuclear reactions in the silicon dominate the detector response. In this energy range the shape of the clusters indicates the neutron kinetic energy.

  16. A new fast-response, real-time and continuous dissolved methane sensor.

    NASA Astrophysics Data System (ADS)

    Triest, Jack; Chappellaz, Jerome; Grilli, Roberto

    2016-04-01

    Continuous high resolution profiling of dissolved methane down to ocean depths is made possible as a result of technological innovations achieved in the search for the oldest ice in Antarctica. Testing for the SUBGLACIOR probe, which is being developed at LGGE in response to the IPICS >1Ma old ice challenge, showed that much of the technology to extract the trapped gases from ice can also significantly improve the extraction and analysis of dissolved methane from the sea compared to current available sensors. To develop this potential, an oceanographic instrument 'SubOcean' was built and deployed over a gas-hydrate zone of western Svalbard, in collaboration with CAGE, in October 2015. Continuous measurements to depths of 400 m were made over three days resulting in high-resolution 3D profiles. The very fast response time of the sensor allows to display the in-situ measurements in real-time and compare them directly to data from other instrumentation aboard the ship whilst underway. The sensor contains a membrane based gas extraction system coupled to a laser spectrometer to provide accurate measurements over a wide concentration range. We will present the overall design of the instrument and highlight how it can help provide new insights into the spatial distribution and flux of methane in the marine environment.

  17. A real-time fast radio burst: polarization detection and multiwavelength follow-up

    NASA Astrophysics Data System (ADS)

    Petroff, E.; Bailes, M.; Barr, E. D.; Barsdell, B. R.; Bhat, N. D. R.; Bian, F.; Burke-Spolaor, S.; Caleb, M.; Champion, D.; Chandra, P.; Da Costa, G.; Delvaux, C.; Flynn, C.; Gehrels, N.; Greiner, J.; Jameson, A.; Johnston, S.; Kasliwal, M. M.; Keane, E. F.; Keller, S.; Kocz, J.; Kramer, M.; Leloudas, G.; Malesani, D.; Mulchaey, J. S.; Ng, C.; Ofek, E. O.; Perley, D. A.; Possenti, A.; Schmidt, B. P.; Shen, Yue; Stappers, B.; Tisserand, P.; van Straten, W.; Wolf, C.

    2015-02-01

    Fast radio bursts (FRBs) are one of the most tantalizing mysteries of the radio sky; their progenitors and origins remain unknown and until now no rapid multiwavelength follow-up of an FRB has been possible. New instrumentation has decreased the time between observation and discovery from years to seconds, and enables polarimetry to be performed on FRBs for the first time. We have discovered an FRB (FRB 140514) in real-time on 2014 May 14 at 17:14:11.06 UTC at the Parkes radio telescope and triggered follow-up at other wavelengths within hours of the event. FRB 140514 was found with a dispersion measure (DM) of 562.7(6) cm-3 pc, giving an upper limit on source redshift of z ≲ 0.5. FRB 140514 was found to be 21 ± 7 per cent (3σ) circularly polarized on the leading edge with a 1σ upper limit on linear polarization <10 per cent. We conclude that this polarization is intrinsic to the FRB. If there was any intrinsic linear polarization, as might be expected from coherent emission, then it may have been depolarized by Faraday rotation caused by passing through strong magnetic fields and/or high-density environments. FRB 140514 was discovered during a campaign to re-observe known FRB fields, and lies close to a previous discovery, FRB 110220; based on the difference in DMs of these bursts and time-on-sky arguments, we attribute the proximity to sampling bias and conclude that they are distinct objects. Follow-up conducted by 12 telescopes observing from X-ray to radio wavelengths was unable to identify a variable multiwavelength counterpart, allowing us to rule out models in which FRBs originate from nearby (z < 0.3) supernovae and long duration gamma-ray bursts.

  18. Radiative tearing - Magnetic reconnection on a fast thermal-instability time scale

    NASA Technical Reports Server (NTRS)

    Steinolfson, R. S.; Van Hoven, G.

    1984-01-01

    Two energy modification mechanisms which are known to occur in sheared magnetic fields are the tearing and thermal instabilities. These processes can be studied separately with formalisms incorporating just the effective driving mechanism of interest (finite resistivity for the tearing mode and unstable radiation for the thermal mode). A model which includes both effects, and a temperature-dependent resistivity, indicates that modified forms of these two instabilities may coexist for identical physical conditions. When they are isolated computationally, one can show that their limiting growth rates are approximately those of the uncoupled instabilities. The spatial structure and energy content of these two new hybrid processes are then individually examined and are found to differ considerably from those obtained from separate treatments of the driving mechanisms. The faster radiative instability, which has a hydromagnetically scaled growth rate like the condensation mode of the thermal instability, is shown to involve a substantial amount of magnetic field reconnection. This can be partially explained by a large temperature drop (or resistivity rise) at the X-point. The island width of the Coulomb-coupled radiative mode is 30 percent of that produced by a comparable level of the slower tearing instability. In addition, the perturbed magnetic energy in the radiative instability is 5 times that of the perturbed thermal energy, indicating an appreciable modification of the initial magnetic structure.

  19. Limits on fast radio bursts at 145 MHz with ARTEMIS, a real-time software backend

    NASA Astrophysics Data System (ADS)

    Karastergiou, A.; Chennamangalam, J.; Armour, W.; Williams, C.; Mort, B.; Dulwich, F.; Salvini, S.; Magro, A.; Roberts, S.; Serylak, M.; Doo, A.; Bilous, A. V.; Breton, R. P.; Falcke, H.; Grießmeier, J.-M.; Hessels, J. W. T.; Keane, E. F.; Kondratiev, V. I.; Kramer, M.; van Leeuwen, J.; Noutsos, A.; Osłowski, S.; Sobey, C.; Stappers, B. W.; Weltevrede, P.

    2015-09-01

    Fast radio bursts (FRBs) are millisecond radio signals that exhibit dispersion larger than what the Galactic electron density can account for. We have conducted a 1446 h survey for FRBs at 145 MHz, covering a total of 4193 deg2 on the sky. We used the UK station of the low frequency array (LOFAR) radio telescope - the Rawlings Array - accompanied for a majority of the time by the LOFAR station at Nançay, observing the same fields at the same frequency. Our real-time search backend, Advanced Radio Transient Event Monitor and Identification System - ARTEMIS, utilizes graphics processing units to search for pulses with dispersion measures up to 320 cm-3 pc. Previous derived FRB rates from surveys around 1.4 GHz, and favoured FRB interpretations, motivated this survey, despite all previous detections occurring at higher dispersion measures. We detected no new FRBs above a signal-to-noise threshold of 10, leading to the most stringent upper limit yet on the FRB event rate at these frequencies: 29 sky-1 d-1 for five ms-duration pulses above 62 Jy. The non-detection could be due to scatter-broadening, limitations on the volume and time searched, or the shape of FRB flux density spectra. Assuming the latter and that FRBs are standard candles, the non-detection is compatible with the published FRB sky rate, if their spectra follow a power law with frequency (∝ να), with α ≳ +0.1, demonstrating a marked difference from pulsar spectra. Our results suggest that surveys at higher frequencies, including the low frequency component of the Square Kilometre Array, will have better chances to detect, estimate rates and understand the origin and properties of FRBs.

  20. Sampling frequency, response times and embedded signal filtration in fast, high efficiency liquid chromatography: A tutorial.

    PubMed

    Wahab, M Farooq; Dasgupta, Purnendu K; Kadjo, Akinde F; Armstrong, Daniel W

    2016-02-11

    With increasingly efficient columns, eluite peaks are increasingly narrower. To take full advantage of this, choice of the detector response time and the data acquisition rate a.k.a. detector sampling frequency, have become increasingly important. In this work, we revisit the concept of data sampling from the theorem variously attributed to Whittaker, Nyquist, Kotelnikov, and Shannon. Focusing on time scales relevant to the current practice of high performance liquid chromatography (HPLC) and optical absorbance detection (the most commonly used method), even for very narrow simulated peaks Fourier transformation shows that theoretical minimum sampling frequency is still relatively low (<10 Hz). However, this consideration alone may not be adequate for real chromatograms when an appreciable amount of noise is present. Further, depending on the instrument, the manufacturer's choice of a particular data bunching/integration/response time condition may be integrally coupled to the sampling frequency. In any case, the exact nature of signal filtration often occurs in a manner neither transparent to nor controllable by the user. Using fast chromatography on a state-of-the-art column (38,000 plates), we evaluate the responses produced by different present generation instruments, each with their unique black box digital filters. We show that the common wisdom of sampling 20 points per peak can be inadequate for high efficiency columns and that the sampling frequency and response choices do affect the peak shape. If the sampling frequency is too low or response time is too large, the observed peak shapes will not remain as narrow as they really are - this is especially true for high efficiency and high speed separations. It is shown that both sampling frequency and digital filtering affect the retention time, noise amplitude, peak shape and width in a complex fashion. We show how a square-wave driven light emitting diode source can reveal the nature of the embedded filter

  1. The importance of land hydrology changes in sea level rise on decadal time scales: results from 2002-2014 using GRACE

    NASA Astrophysics Data System (ADS)

    Reager, John; Gardner, Alex; Famiglietti, James; Wiese, David; Eicker, Annette; Lo, Min-Hui

    2016-04-01

    Climate-driven changes in land hydrology and their contributions to sea level rise have been absent from IPCC sea level budgets owing to challenges in observing global land water storage. In a review of recent and ongoing work, we show that recent advances in the measurement of time variable gravity from space using Gravity Recovery and Climate Experiment (GRACE) mission observations, combined with reconciled global glacier loss estimates, enable a disaggregation of continental water mass trends and a quantification of this climate-driven term. We find that between 2002 and 2014, can additional 3200 +/- 900 Gt of water was stored on land in snow, soils and groundwater, likely due to climate variability. This gain partially offset water losses from ice sheets, glaciers, and groundwater pumping, slowing the rate of sea level rise by 0.71 +/- 0.20 mm yr-1, and consistent with observations of slowing over the recent decade. We also discuss possible causes and contributors to these trends and their implications for decadal variability. These findings highlight the importance of climate-driven changes in hydrology when assigning attribution to decadal changes in sea level.

  2. Excited state lifetimes in 190Tc and 109Ru via the fast-timing method

    NASA Astrophysics Data System (ADS)

    Smith, M. K.; Bucher, B.; Aprahamian, A.; Mach, H.; Simpson, G.; Rissanen, J.; Aysto, J.; Eronen, T.; Ghita, D.; Karvonen, P.; Jokinen, A.; Moore, I. D.; Pentilla, H.; Reponen, M.; Weber, C.; Saastamoinen, A.; Kurcewicz, W.; Fraile, I. M.; Olaizola, B.; Ruchowska, E.

    2013-10-01

    The evolution of nuclear structure across isotopic and isobaric chains are of great interest to nuclear structure and for structure applications to nuclear astrophysics, specifically the r-process. The neutron-rich region around A = 110 is characterized by rapidly evolving structure, which is currently not completely understood. As such, we have investigated the A = 109 β-decay chain at the Univ. of Jyvaskyla IGISOL facility. 109Mo was populated via proton-induced fission of 238U, which β- decays to 109Tc and subsequently 109Ru. Lifetimes and gamma spectroscopy were measured with a multi-detector array consisting of of 2 HPGe, 2 LaBr and 1 plastic scintillator. β- γ- γ triple coincidences were used to construct/check both level schemes, and measure lifetimes by the fast-timing method. New gamma ray transitions and picosecond range lifetimes will be presented for 109Tc and 109Ru. This work is supported by the NSF under grants PHY0822648 and PHY0758100; and by the Academy of Finland under the Centre of Excellence Programme 2006-2011.

  3. Fast-Time Evaluations of Airborne Merging and Spacing in Terminal Arrival Operations

    NASA Technical Reports Server (NTRS)

    Krishnamurthy, Karthik; Barmore, Bryan; Bussink, Frank; Weitz, Lesley; Dahlene, Laura

    2005-01-01

    NASA researchers are developing new airborne technologies and procedures to increase runway throughput at capacity-constrained airports by improving the precision of inter-arrival spacing at the runway threshold. In this new operational concept, pilots of equipped aircraft are cleared to adjust aircraft speed to achieve a designated spacing interval at the runway threshold, relative to a designated lead aircraft. A new airborne toolset, prototypes of which are being developed at the NASA Langley Research Center, assists pilots in achieving this objective. The current prototype allows precision spacing operations to commence even when the aircraft and its lead are not yet in-trail, but are on merging arrival routes to the runway. A series of fast-time evaluations of the new toolset were conducted at the Langley Research Center during the summer of 2004. The study assessed toolset performance in a mixed fleet of aircraft on three merging arrival streams under a range of operating conditions. The results of the study indicate that the prototype possesses a high degree of robustness to moderate variations in operating conditions.

  4. Exploration of ultra-fast electron dynamics using time-dependent R-matrix theory

    NASA Astrophysics Data System (ADS)

    van der Hart, Hugo; Rey, Hector; Hassouneh, Ola; Brown, Andrew

    2014-05-01

    When an atom is subjected to an intense laser field, the full atomic response can involve a collective response involving several electrons. This collective response will be affected by electron-electron repulsion, coupling the overall electron dynamics. In order to investigate this dynamics for a multi-electron system from first principles, we have developed time-dependent R-matrix theory. The theory applies the basic principles of R-matrix theory, in which all interactions between all electrons are taken into account close to the nucleus, but exchange interactions are neglected when one electron has become distanced from the parent atom. In this contribution, we will explain the basic principles of this theory and demonstrate its application to ultra-fast dynamics in C+, and harmonic generation in singly ionised noble-gas atoms. Both studies demonstrate that it is important to go beyond the single-active-electron approximation. This research has been supported by EPSRC UK, and by the EU Initial Training Network CORINF.

  5. Fast determination of earthquake magnitude and fault extent from real-time P-wave recordings

    NASA Astrophysics Data System (ADS)

    Colombelli, Simona; Zollo, Aldo

    2015-08-01

    This work is aimed at the automatic and fast characterization of the extended earthquake source, through the progressive measurement of the P-wave displacement amplitude along the recorded seismograms. We propose a straightforward methodology to quickly characterize the earthquake magnitude and the expected length of the rupture, and to provide an approximate estimate of the average stress drop to be used for Earthquake Early Warning and rapid response purposes. We test the methodology over a wide distance and magnitude range using a massive Japan earthquake, accelerogram data set. Our estimates of moment magnitude, source duration/length and stress drop are consistent with the ones obtained by using other techniques and analysing the whole seismic waveform. In particular, the retrieved source parameters follow a self-similar, constant stress-drop scaling (median value of stress drop = 0.71 MPa). For the M 9.0, 2011 Tohoku-Oki event, both magnitude and length are underestimated, due to limited, available P-wave time window (PTWs) and to the low-frequency cut-off of analysed data. We show that, in a simulated real-time mode, about 1-2 seconds would be required for the source parameter determination of M 4-5 events, 3-10 seconds for M 6-7 and 30-40 s for M 8-8.5. The proposed method can also provide a rapid evaluation of the average slip on the fault plane, which can be used as an additional discriminant for tsunami potential, associated to large magnitude earthquakes occurring offshore.

  6. A Fast Topological Trigger for Real Time Analysis of Nanosecond Phenomena; Opening the Gamma Ray Window to Our Universe

    SciTech Connect

    Krennrich, Frank

    2013-09-24

    This work was to enable the development of a proof-of-principle nanosecond trigger system that is designed to perform a real time analysis of fast Cherenkov light flashes from air showers. The basic building blocks of the trigger system have been designed and constructed, and a real world system is now operating in the VERITAS experiment.

  7. Determinants of Children's Use of and Time Spent in Fast-Food and Full-Service Restaurants

    ERIC Educational Resources Information Center

    McIntosh, Alex; Kubena, Karen S.; Tolle, Glen; Dean, Wesley; Kim, Mi-Jeong; Jan, Jie-Sheng; Anding, Jenna

    2011-01-01

    Objective: Identify parental and children's determinants of children's use of and time spent in fast-food (FF) and full-service (FS) restaurants. Design: Analysis of cross-sectional data. Setting: Parents were interviewed by phone; children were interviewed in their homes. Participants: Parents and children ages 9-11 or 13-15 from 312 families…

  8. Time-resolved observation of fast domain-walls driven by vertical spin currents in short tracks

    NASA Astrophysics Data System (ADS)

    Sampaio, Joao; Lequeux, Steven; Metaxas, Peter J.; Chanthbouala, Andre; Matsumoto, Rie; Yakushiji, Kay; Kubota, Hitoshi; Fukushima, Akio; Yuasa, Shinji; Nishimura, Kazumasa; Nagamine, Yoshinori; Maehara, Hiroki; Tsunekawa, Koji; Cros, Vincent; Grollier, Julie

    2013-12-01

    We present time-resolved measurements of the displacement of magnetic domain-walls (DWs) driven by vertical spin-polarized currents in track-shaped magnetic tunnel junctions. In these structures, we observe very high DW velocities (600 m/s) at current densities below 107 A/cm2. We show that the efficient spin-transfer torque combined with a short propagation distance allows avoiding the Walker breakdown process and achieving deterministic, reversible, and fast (≈1 ns) DW-mediated switching of magnetic tunnel junction elements, which is of great interest for the implementation of fast DW-based spintronic devices.

  9. Time-resolved observation of fast domain-walls driven by vertical spin currents in short tracks

    SciTech Connect

    Sampaio, Joao; Lequeux, Steven; Chanthbouala, Andre; Cros, Vincent; Grollier, Julie; Matsumoto, Rie; Yakushiji, Kay; Kubota, Hitoshi; Fukushima, Akio; Yuasa, Shinji; Nishimura, Kazumasa; Nagamine, Yoshinori; Maehara, Hiroki; Tsunekawa, Koji

    2013-12-09

    We present time-resolved measurements of the displacement of magnetic domain-walls (DWs) driven by vertical spin-polarized currents in track-shaped magnetic tunnel junctions. In these structures, we observe very high DW velocities (600 m/s) at current densities below 10{sup 7} A/cm{sup 2}. We show that the efficient spin-transfer torque combined with a short propagation distance allows avoiding the Walker breakdown process and achieving deterministic, reversible, and fast (≈1 ns) DW-mediated switching of magnetic tunnel junction elements, which is of great interest for the implementation of fast DW-based spintronic devices.

  10. Development of the N1-P2 auditory evoked response to amplitude rise time and rate of formant transition of speech sounds.

    PubMed

    Carpenter, Allen L; Shahin, Antoine J

    2013-06-01

    We investigated the development of weighting strategies for acoustic cues by examining the morphology of the N1-P2 auditory evoked potential (AEP) to changes in amplitude rise time (ART) and rate of formant transition (RFT) of consonant-vowel (CV) pairs in 4-6-year olds and adults. In the AEP session, individuals listened passively to the CVs /ba/, /wa/, and a /ba/ with a superimposed slower-rising /wa/ envelope (/ba/(wa)). In the behavioral session, individuals listened to the same stimuli and judged whether they heard a /ba/ or /wa/. We hypothesized that a developmental shift in weighting strategies should be reflected in a change in the morphology of the N1-P2 AEP. In 6-year olds and adults, the N1-P2 amplitude at the vertex reflected a change in RFT but not in ART. In contrast, in the 4-5-year olds, the vertex N1-P2 did not show specificity to changes in ART or RFT. In all groups, the N1-P2 amplitude at channel C4 (right hemisphere) reflected a change in ART but not in RFT. Behaviorally, 6-year olds and adults predominately utilized RFT cues (classified /ba/(wa) as /ba/) during phonetic judgments, as opposed to 4-5-year olds which utilized both cues equally. Our findings suggest that both ART and RFT are encoded in the auditory cortex, but an N1-P2 shift toward the vertex following age 4-5 indicates a shift toward an adult-like weighting strategy, such that, to utilize RFT to a greater extent. PMID:23570734

  11. Ultra-fast consensus of discrete-time multi-agent systems with multi-step predictive output feedback

    NASA Astrophysics Data System (ADS)

    Zhang, Wenle; Liu, Jianchang

    2016-04-01

    This article addresses the ultra-fast consensus problem of high-order discrete-time multi-agent systems based on a unified consensus framework. A novel multi-step predictive output mechanism is proposed under a directed communication topology containing a spanning tree. By predicting the outputs of a network several steps ahead and adding this information into the consensus protocol, it is shown that the asymptotic convergence factor is improved by a power of q + 1 compared to the routine consensus. The difficult problem of selecting the optimal control gain is solved well by introducing a variable called convergence step. In addition, the ultra-fast formation achievement is studied on the basis of this new consensus protocol. Finally, the ultra-fast consensus with respect to a reference model and robust consensus is discussed. Some simulations are performed to illustrate the effectiveness of the theoretical results.

  12. Measurements of the fast ion slowing-down times in the HL-2A tokamak and comparison to classical theory

    SciTech Connect

    Zhang, Y. P.; Liu, Yi; Yuan, G. L.; Yang, J. W.; Song, X. Y.; Song, X. M.; Cao, J. Y.; Lei, G. J.; Wei, H. L.; Li, Y. G.; Shi, Z. B.; Li, X.; Yan, L. W.; Yang, Q. W.; Duan, X. R.; Isobe, M.; Collaboration: HL-2A Team

    2012-11-15

    Physics related to fast ions in magnetically confined fusion plasmas is a very important issue, since these particles will play an important role in future burning plasmas. Indeed, they will act as primary heating source and will sustain the self-ignited condition. To measure the fast ion slowing-down times in a magnetohydrodynamic-quiescent plasmas in different scenarios, very short pulses of a deuterium neutral beam, so-called 'blip,' with duration of about 5 ms were tangentially co-injected into a deuterium plasmas at the HuanLiuqi-2A (commonly referred to as HL-2A) tokamak [L. W. Yan, Nucl. Fusion 51, 094016 (2011)]. The decay rate of 2.45 MeV D-D fusion neutrons produced by beam-plasma reactions following neutral beam termination was measured by means of a {sup 235}U fission chamber. Experimental results were compared with those predicted by a classical slowing-down model. These results show that the fast ions are well confined with a peaked profile and the ions are slowed down classically without significant loss in the HL-2A tokamak. Moreover, it has been observed that during electron cyclotron resonance heating the fast ions have a longer slowing-down time and the neutron emission rate decay time becomes longer.

  13. Crustal thickness and Moho character of the fast-spreading East Pacific Rise from 9°42'N to 9°57'N from poststack-migrated 3-D MCS data

    NASA Astrophysics Data System (ADS)

    Aghaei, Omid; Nedimović, Mladen R.; Carton, Helene; Carbotte, Suzanne M.; Canales, J. Pablo; Mutter, John C.

    2014-03-01

    computed crustal thickness (5740 ± 270 m) and mapped Moho reflection character using 3-D seismic data covering 658 km2 of the fast-spreading East Pacific Rise (EPR) from 9°42'N to 9°57'N. Moho reflections are imaged within ˜87% of the study area. Average crustal thickness varies little between large sections of the study area suggesting regionally uniform crustal production in the last ˜180 Ka. However, individual crustal thickness measurements differ by as much as 1.75 km indicating that the mantle melt delivery has not been uniform. Third-order, but not fourth-order ridge discontinuities are associated with changes in the Moho reflection character and/or near-axis crustal thickness. This suggests that the third-order segmentation is governed by melt distribution processes within the uppermost mantle while the fourth-order ridge segmentation arises from midcrustal to upper-crustal processes. In this light, we assign fourth-order ridge discontinuity status to the debated ridge segment boundary at ˜9°45'N and third-order status at ˜9°51.5'N to the ridge segment boundary previously interpreted as a fourth-order discontinuity. Our seismic results also suggest that the mechanism of lower-crustal accretion varies along the investigated section of the EPR but that the volume of melt delivered to the crust is mostly uniform. More efficient mantle melt extraction is inferred within the southern half of our survey area with greater proportion of the lower crust accreted from the axial magma lens than that for the northern half. This south-to-north variation in the crustal accretion style may be caused by interaction between the melt sources for the ridge and the Lamont seamounts.

  14. A novel Fast Gas Chromatography based technique for higher time resolution measurements of speciated monoterpenes in air

    NASA Astrophysics Data System (ADS)

    Jones, C. E.; Kato, S.; Nakashima, Y.; Kajii, Y.

    2013-12-01

    Biogenic emissions supply the largest fraction of non-methane volatile organic compounds (VOC) from the biosphere to the atmospheric boundary layer, and typically comprise a complex mixture of reactive terpenes. Due to this chemical complexity, achieving comprehensive measurements of biogenic VOC (BVOC) in air within a satisfactory time resolution is analytically challenging. To address this, we have developed a novel, fully automated Fast Gas Chromatography (Fast-GC) based technique to provide higher time resolution monitoring of monoterpenes (and selected other C9-C15 terpenes) during plant emission studies and in ambient air. To our knowledge, this is the first study to apply a Fast-GC based separation technique to achieve quantification of terpenes in air. Three chromatography methods have been developed for atmospheric terpene analysis under different sampling scenarios. Each method facilitates chromatographic separation of selected BVOC within a significantly reduced analysis time compared to conventional GC methods, whilst maintaining the ability to quantify individual monoterpene structural isomers. Using this approach, the C10-C15 BVOC composition of single plant emissions may be characterised within a ~ 14 min analysis time. Moreover, in situ quantification of 12 monoterpenes in unpolluted ambient air may be achieved within an ~ 11 min chromatographic separation time (increasing to ~ 19 min when simultaneous quantification of multiple oxygenated C9-C10 terpenoids is required, and/or when concentrations of anthropogenic VOC are significant). This corresponds to a two- to fivefold increase in measurement frequency compared to conventional GC methods. Here we outline the technical details and analytical capability of this chromatographic approach, and present the first in situ Fast-GC observations of 6 monoterpenes and the oxygenated BVOC linalool in ambient air. During this field deployment within a suburban forest ~ 30 km west of central Tokyo, Japan, the

  15. Fast time resolution measurements of high concentrations of iodine above a Laminaria Digitata seaweed bed

    NASA Astrophysics Data System (ADS)

    Ball, Stephen; Adams, Thomas; Leblanc, Catherine; Potin, Philippe

    2013-04-01

    -distant seaweeds whose emissions are better-mixed into the atmosphere. The peak I2 concentrations observed here are three to five times greater than the maximum amounts recorded above/closeby laminaria beds in previous studies: 350 pptv max in O Grove, Galicia, Spain (Mahajan et al., ACP, 11, 2545, 2011), and 302 and 547 pptv max at Mweenish Bay, near Mace Head, County Galway, Ireland (Huang et al., GRL, 37, L03803, 2010; ACPD, 12, 25915, 2012). In part, the larger peak concentrations seen here are a consequence of deploying a fast response instrument very close to the source, enabling the emission's high temporal variability to be captured with fewer averaging effects. Nevertheless, the I2 concentrations averaged over the 30 minute period around the tidal minimum were still typically 750 pptv, suggesting laminaria beds are even stronger emitters of I2 into coastal atmospheres than previously thought. Some implications for such high concentrations of iodine for the local atmospheric chemistry are considered. We acknowledge support from the European Community FP7 project "ASSEMBLE", grant 227799.

  16. Melting Ice, Rising Seas

    NASA Video Gallery

    Sea level rise is an indicator that our planet is warming. Much of the world's population lives on or near the coast, and rising seas are something worth watching. Sea level can rise for two reason...

  17. SOA Does Not Reveal the Absolute Time Course of Cognitive Processing in Fast Priming Experiments

    ERIC Educational Resources Information Center

    Tzur, Boaz; Frost, Ram

    2007-01-01

    Applying Bloch's law to visual word recognition research, both exposure duration of the prime and its luminance determine the prime's overall energy, and consequently determine the size of the priming effect. Nevertheless, experimenters using fast-priming paradigms traditionally focus only on the SOA between prime and target to reflect the…

  18. Getting back on the beat: links between auditory-motor integration and precise auditory processing at fast time scales.

    PubMed

    Tierney, Adam; Kraus, Nina

    2016-03-01

    The auditory system is unique in its ability to precisely detect the timing of perceptual events and use this information to update motor plans, a skill that is crucial for language. However, the characteristics of the auditory system that enable this temporal precision are only beginning to be understood. Previous work has shown that participants who can tap consistently to a metronome have neural responses to sound with greater phase coherence from trial to trial. We hypothesized that this relationship is driven by a link between the updating of motor output by auditory feedback and neural precision. Moreover, we hypothesized that neural phase coherence at both fast time scales (reflecting subcortical processing) and slow time scales (reflecting cortical processing) would be linked to auditory-motor timing integration. To test these hypotheses, we asked participants to synchronize to a pacing stimulus, and then changed either the tempo or the timing of the stimulus to assess whether they could rapidly adapt. Participants who could rapidly and accurately resume synchronization had neural responses to sound with greater phase coherence. However, this precise timing was limited to the time scale of 10 ms (100 Hz) or faster; neural phase coherence at slower time scales was unrelated to performance on this task. Auditory-motor adaptation therefore specifically depends upon consistent auditory processing at fast, but not slow, time scales. PMID:26750313

  19. Demanding response time requirements on coherent receivers due to fast polarization rotations caused by lightning events.

    PubMed

    Krummrich, Peter M; Ronnenberg, David; Schairer, Wolfgang; Wienold, Daniel; Jenau, Frank; Herrmann, Maximilian

    2016-05-30

    Lightning events can cause fast polarization rotations and phase changes in optical transmission fibers due to strong electrical currents and magnetic fields. Whereas these are unlikely to affect legacy transmission systems with direct detection, different mechanisms have to be considered in systems with local oscillator based coherent receivers and digital signal processing. A theoretical analysis reveals that lightning events can result in polarization rotations with speeds as fast as a few hundred kRad/s. We discuss possible mechanisms how such lightning events can affect coherent receivers with digital signal processing. In experimental investigations with a high current pulse generator and transponder prototypes, we observed post FEC errors after polarization rotation events which can be expected from lightning strikes. PMID:27410158

  20. Sonic-boom measurements in the focus region during the ascent of Apollo 17. [maximum positive overpressure, positive impulse, signature duration, and bow-shock rise time

    NASA Technical Reports Server (NTRS)

    Henderson, H. R.; Hilton, D. A.

    1974-01-01

    Sonic-boom pressure signatures recorded during the ascent phase of Apollo 17 are presented. The measurements were obtained onboard six U.S. Navy ships positioned along the ground track of the spacecraft vehicle in the area of expected focus resulting from the flight path and acceleration of the vehicle. Tracings of the measured signatures are presented along with values of the maximum positive overpressure, positive impulse, signature duration, and bowshock rise time. Also included are brief descriptions of the ships and their location, the deployment of the sonic-boom instrumentation, flight profiles and operating conditions for the launch vehicle and spacecraft, surface-weather and sea-state information at the measuring sites, and high-altitude weather information for the general measurement areas. Comparisons of the measured and predicted sonic-boom overpressures for the Apollo 17 mission are presented. The measured data are also compared with data from the Apollo 15 and 16 missions and data from flight test programs of various aircraft.

  1. Optimal battery charging, Part I: Minimizing time-to-charge, energy loss, and temperature rise for OCV-resistance battery model

    NASA Astrophysics Data System (ADS)

    Abdollahi, A.; Han, X.; Avvari, G. V.; Raghunathan, N.; Balasingam, B.; Pattipati, K. R.; Bar-Shalom, Y.

    2016-01-01

    In this paper we present a closed-form solution to the problem of optimally charging a Li-ion battery. A combination of three cost functions is considered as the objective function: time-to-charge (TTC), energy losses (EL), and a temperature rise index (TRI). First, we consider the cost function of the optimization problem as a weighted sum of TTC and EL. We show that the optimal charging strategy in this case is the well-known Constant Current-Constant Voltage (CC-CV) policy with the value of the current in the CC stage being a function of the ratio of weighting on TTC and EL and of the resistance of the battery. Then, we extend the cost function to a weighted sum of TTC, EL and TRI and derive an analytical solution for the problem. It is shown that the analytical solution can be approximated by a CC-CV with the value of current in the CC stage being a function of ratio of weighting on TTC and EL, resistance of the battery and the effective thermal resistance.

  2. Contemporary sea level rise.

    PubMed

    Cazenave, Anny; Llovel, William

    2010-01-01

    Measuring sea level change and understanding its causes has considerably improved in the recent years, essentially because new in situ and remote sensing observations have become available. Here we report on most recent results on contemporary sea level rise. We first present sea level observations from tide gauges over the twentieth century and from satellite altimetry since the early 1990s. We next discuss the most recent progress made in quantifying the processes causing sea level change on timescales ranging from years to decades, i.e., thermal expansion of the oceans, land ice mass loss, and land water-storage change. We show that for the 1993-2007 time span, the sum of climate-related contributions (2.85 +/- 0.35 mm year(-1)) is only slightly less than altimetry-based sea level rise (3.3 +/- 0.4 mm year(-1)): approximately 30% of the observed rate of rise is due to ocean thermal expansion and approximately 55% results from land ice melt. Recent acceleration in glacier melting and ice mass loss from the ice sheets increases the latter contribution up to 80% for the past five years. We also review the main causes of regional variability in sea level trends: The dominant contribution results from nonuniform changes in ocean thermal expansion. PMID:21141661

  3. Dynamics of reactive high-power impulse magnetron sputtering discharge studied by time- and space-resolved optical emission spectroscopy and fast imaging

    SciTech Connect

    Hala, M.; Viau, N.; Zabeida, O.; Klemberg-Sapieha, J. E.; Martinu, L.

    2010-02-15

    Time- and space-resolved optical emission spectroscopy and fast imaging were used for the investigation of the plasma dynamics of high-power impulse magnetron sputtering discharges. 200 {mu}s pulses with a 50 Hz repetition frequency were applied to a Cr target in Ar, N{sub 2}, and N{sub 2}/Ar mixtures and in a pressure range from 0.7 to 2.66 Pa. The power density peaked at 2.2-6 kW cm{sup -2}. Evidence of dominating self-sputtering was found for all investigated conditions. Up to four different discharge phases within each pulse were identified: (i) the ignition phase, (ii) the high-current metal-dominated phase, (iii) the transient phase, and (iv) the low-current gas-dominated phase. The emission of working gas excited by fast electrons penetrating the space in-between the electrodes during the ignition phase spread far outwards from the target at a speed of 24 km s{sup -1} in 1.3 Pa of Ar and at 7.5 km s{sup -1} in 1.3 Pa of N{sub 2}. The dense metal plasma created next to the target propagated in the reactor at a speed ranging from 0.7 to 3.5 km s{sup -1}, depending on the working gas composition and the pressure. In fact, it increased with higher N{sub 2} concentration and lower pressure. The form of the propagating plasma wave changed from a hemispherical shape in Ar, to a droplike shape extending far from the target in N{sub 2}. An important N{sub 2} emission rise in the latter case was detected during the transition at the end of the metal-dominated phase.

  4. Speckle-based sensor system for real-time distance and thickness monitoring of fast moving objects

    NASA Astrophysics Data System (ADS)

    Semenov, D. V.; Sidorov, I. S.; Nippolainen, E.; Kamshilin, A. A.

    2010-04-01

    Real-time distance monitoring and thickness measurements of production lines are typical tasks of the manufacturing process. We demonstrate a novel optical sensor prototype capable of providing accurate distance measurements of fast moving objects. The principle of sensor operation is based on spatial filtering of dynamic speckles generated with a scanning laser beam. The sensor is able to measure the distance to opaque (metals, etc) and to multi-scattering materials (papers, plastics, etc). The presented sensor prototype provides measurements and data processing in real time. We verify sensor prototype performance of multi-scattering material (paper web) moving with a speed of 35 m s-1.

  5. Wide and fast wavelength-swept fiber lasers based on dispersion tuning for real-time OCT

    NASA Astrophysics Data System (ADS)

    Yamashita, S.; Takubo, Y.

    2014-05-01

    Swept-Source Optical coherence tomography (SS-OCT) is a powerful tool for fast medical imaging. For the real-time 3D imaging, the wide tuning range over 100 nm and fast sweep rate over 100 kHz are typically required. We recently proposed a new wavelength-swept laser for SS-OCT. It is based on a principle called dispersion tuning. Since the cavity contains no mechanical components, such as tunable filters, we could achieve the very high sweep rate. In this review paper, we describe the principle of the dispersion-tuned swept lasers in detail and present our recent works on the application to the SS-OCT system.

  6. The effects of time pressure on chess skill: an investigation into fast and slow processes underlying expert performance.

    PubMed

    van Harreveld, Frenk; Wagenmakers, Eric-Jan; van der Maas, Han L J

    2007-09-01

    The ability to play chess is generally assumed to depend on two types of processes: slow processes such as search, and fast processes such as pattern recognition. It has been argued that an increase in time pressure during a game selectively hinders the ability to engage in slow processes. Here we study the effect of time pressure on expert chess performance in order to test the hypothesis that compared to weak players, strong players depend relatively heavily on fast processes. In the first study we examine the performance of players of various strengths at an online chess server, for games played under different time controls. In a second study we examine the effect of time controls on performance in world championship matches. Both studies consistently show that skill differences between players become less predictive of the game outcome as the time controls are tightened. This result indicates that slow processes are at least as important for strong players as they are for weak players. Our findings pose a challenge for current theorizing in the field of expertise and chess. PMID:17186308

  7. Effect of Current Rise-time on the Formation of Precursor Structures and Mass Ablation Rate in Cylindrical Wire Array Z-Pinches

    SciTech Connect

    Bott, S. C.; Eshaq, Y.; Ueda, U.; Haas, D. M.; Beg, F. N.; Hammer, D. A.; Kusse, B.; Greenly, J.; Shelkovenko, T. A.; Pikuz, S. A.; Blesener, I. C.; McBride, R. D.; Douglass, J. D.; Bell, K.; Knapp, P.; Chittenden, J. P.; Lebedev, S. V.; Bland, S. N.; Hall, G. N.; Suzuki, F. A.

    2009-01-21

    We present the first study to directly compare the mass ablation rates of cylindrical wire arrays as a function of the current rise-rate. Formation of the precursor column is investigated on both the MAPGIE (1 MA, 250 ns) and COBRA (1 MA, 100 ns) generators, and results are used to infer the change in the mass ablation rate induced by the rise-rate of the drive current. Laser shadowography, gated XUV imaging and x-ray diodes are used to compare the dynamical behavior both generators, and x-pinch radiography and XUV spectroscopy and provide density evolution and temperature measurements respectively. Results are compared to predictions from an analytical scaling model based on a fixed ablation rate, and the close correlation achieved suggests that the effective ablation velocity is not a strong function of the current rise rate.

  8. Interlaboratory Validation for a Real-Time PCR Salmonella Detection Method Using the ABI 7500 FAST Real-Time PCR System.

    PubMed

    Cheng, Chorng-Ming; Doran, Tara; Lin, Wen; Chen, Kai-Shun; Williams-Hill, Donna; Pamboukian, Ruiqing

    2015-06-01

    Sixteen FERN (Food Emergency Response Network) member laboratories collaborated in this study to verify extension of the real-time PCR Salmonella detection method originally designed for the single-tube Cepheid SmartCycler II and validated against the Salmonella method of the U. S. Food and Drug Administration Bacteriological Analytical Manual to the Applied Biosystems (ABI) 7500 FAST Real-Time PCR system multiwell plate platform. Four foods were selected for this study: chili powder, soft cheese, fish, and tomatoes; these foods represent products that are commonly analyzed for the presence of Salmonella for regulatory purposes. Each food consisted of six uninoculated control samples, six samples inoculated with low Salmonella levels (target 1 to 5 CFU/25 g), and six samples inoculated with high levels (target 10 to 50 CFU/25 g). All samples were tested for Salmonella using the 24-h quantitative PCR (qPCR) method for detecting Salmonella, which utilizes modified buffered peptone water as the sole enrichment medium and an internal control for the qPCR. Each of these 18 samples was individually analyzed for Salmonella by the collaborating laboratories using both the ABI 7500 FAST system (alternative method) and the SmartCycler II system (reference method). Statistical analysis of the data revealed no significant difference (P ≥ 0.05) between these two qPCR platforms except for the chili powder samples. The differences noted with chili powder (P = 0.0455) were attributed to the enhanced sensitivity of the ABI 7500 FAST system compared with the SmartCycler II system. The detection limit of both qPCR methods was 0.02 to 0.15 CFU/g. These results provide a solid basis for extending the 24-h qPCR Salmonella method to the ABI 7500 FAST system for high-throughput detection of Salmonella in foods. PMID:26038901

  9. Early stage time evolution of a dense nanosecond microdischarge used in fast optical switching applications

    NASA Astrophysics Data System (ADS)

    Levko, Dmitry; Raja, Laxminarayan L.

    2015-12-01

    The mechanism of high-voltage nanosecond microdischarges is studied by the self-consistent two-dimensional Particle-in-Cell/Monte Carlo Collisions model. These microdischarges were recently proposed for use as fast switches of visible light in Bataller et al. [Appl. Phys. Lett. 105, 223501 (2014)]. The microdischarge is found to develop in two stages. The first stage is associated with the electrons initially seeded in the cathode-anode gap. These electrons lead to the formation of a cathode-directed streamer. The second stage starts when the secondary electron emission from the cathode begins. In this stage, a rather dense plasma (˜1016 cm-3) is generated which results in the narrow cathode sheath. The electric field in this sheath exceeds the critical electric field which is necessary for the runaway electrons generation. We have found that the presence of these energetic electrons is crucial for the discharge maintenance.

  10. Early stage time evolution of a dense nanosecond microdischarge used in fast optical switching applications

    SciTech Connect

    Levko, Dmitry; Raja, Laxminarayan L.

    2015-12-15

    The mechanism of high-voltage nanosecond microdischarges is studied by the self-consistent two-dimensional Particle-in-Cell/Monte Carlo Collisions model. These microdischarges were recently proposed for use as fast switches of visible light in Bataller et al. [Appl. Phys. Lett. 105, 223501 (2014)]. The microdischarge is found to develop in two stages. The first stage is associated with the electrons initially seeded in the cathode-anode gap. These electrons lead to the formation of a cathode-directed streamer. The second stage starts when the secondary electron emission from the cathode begins. In this stage, a rather dense plasma (∼10{sup 16 }cm{sup −3}) is generated which results in the narrow cathode sheath. The electric field in this sheath exceeds the critical electric field which is necessary for the runaway electrons generation. We have found that the presence of these energetic electrons is crucial for the discharge maintenance.

  11. Performance of fast monolithic ECL voltage comparators in constant-fraction discriminators and other timing circuits

    SciTech Connect

    Binkley, D.M.; Casey, M.E. )

    1988-02-01

    Timing errors caused by voltage comparator operation are investigated in detail for constant-fraction discriminators and other timing circuits. These errors result from changing comparator response time for input signals with different slopes (voltage/time) and different levels. Comparator response time is analyzed for a modern high-speed ECL voltage comparator using the SPICE circuit analysis program which models the complex nonlinearities present in comparator operation. The simulated response time for a -90 mV to 10 mV step input is slightly larger than the specified comparator performance indicating a conservative analysis. Response time is presented for a variety of input signals and supports a comparator response-time model that consists of a charge-sensitivity (variable-time) delay component and a fixed delay component. Finally, SPICE circuit simulation is extended to simulate comparator operation in a constant-fraction discriminator circuit.

  12. Time Trends in Fast Food Consumption and Its Association with Obesity among Children in China

    PubMed Central

    Wang, Xiaoyu; Wang, Youfa

    2016-01-01

    Objective Study the trends in Western fast food consumption (FFC) among Chinese school-age children and the association between FFC and obesity using nationwide survey data. Design Cross-sectional and longitudinal analyses were conducted to study the trends in FFC and the associations between FFC and weight status (overweight, obesity and body mass index (BMI) z-score). Setting Longitudinal data from families were collected in the 2004 and 2009 China Health and Nutrition Survey (covering nine provinces throughout China). Subjects The analysis included 2656 Chinese children aged 6 to 18 years (1542 and 1114 children in the 2004 and 2009 survey, respectively). Results FFC (reported having consumed Western fast food in the past three months) has increased between 2004 and 2009, from 18.5% to 23.9% in those aged 6–18, and increased more rapidly among those aged 13–17, from 17.9% to 26.3%. The increase was significant in almost all groups by age, sex, family income, and residence. Our cross-sectional and longitudinal analyses did not detect a significant association between FFC and obesity/overweight or BMI z-score (e.g., for BMI z-score, boys: β = 0.02, 95% CI: -0.71, 0.75; girls: β = -0.14, 95% CI: -1.03, 0.75). Conclusions FFC has increased in Chinese school-age children, especially in older children, boys, and those from low- and medium-income families, rural areas, and East China, but decreased among those from high-income families during 2004–2009. The data did not show a significant association between FFC and obesity. PMID:26974536

  13. The potential influence of gastric acid secretion during fasting on digestion time in leopard sharks (Triakis semifasciata).

    PubMed

    Papastamatiou, Yannis P

    2007-05-01

    Vertebrates are known to differ in their response of gastric acid secretion during periods of fasting, yet the reasons for these differences remain unclear. Previously, continuous measurements of gastric pH in leopard sharks (Triakis semifasciata) had determined that acid secretion in this species is continuous. In order to determine if maintaining an empty acidic stomach may reduce digestion time of a subsequent meal, a simple descriptive model based on acid secretion rates was developed. In vivo gastric acid secretion rates were measured using an auto-titration technique. Acid secretion rates were pH dependent, with rates of 6.1+/-3.0 (+/-1 SD) mmol/h when gastric pH was >2.5, and 1.7+/-0.8 mmol/h when pH was 2.0-2.5. Analysis by Western blots suggests that pepsin secretion occurs within 1 h of feeding, and that there is a de-coupling of acid and pepsin secretion. The model estimates that digestion time can be reduced by 5.7+/-1.3 h and pepsin activity increased by 10-100% during that time if the stomach is acidic before feeding. Gastric acid secretion during fasting is hypothesized to reduce digestion time of a subsequent meal in frequently feeding sharks, which may be advantageous for exploiting resources that are spatially and temporally unpredictable. PMID:17280858

  14. Controlling chaos in a fast diode resonator using extended time-delay autosynchronization: Experimental observations and theoretical analysis.

    PubMed

    Sukow, David W.; Bleich, Michael E.; Gauthier, Daniel J.; Socolar, Joshua E. S.

    1997-12-01

    We stabilize unstable periodic orbits of a fast diode resonator driven at 10.1 MHz (corresponding to a drive period under 100 ns) using extended time-delay autosynchronization. Stabilization is achieved by feedback of an error signal that is proportional to the difference between the value of a state variable and an infinite series of values of the state variable delayed in time by integral multiples of the period of the orbit. The technique is easy to implement electronically and it has an all-optical counterpart that may be useful for stabilizing the dynamics of fast chaotic lasers. We show that increasing the weights given to temporally distant states enlarges the domain of control and reduces the sensitivity of the domain of control on the propagation delays in the feedback loop. We determine the average time to obtain control as a function of the feedback gain and identify the mechanisms that destabilize the system at the boundaries of the domain of control. A theoretical stability analysis of a model of the diode resonator in the presence of time-delay feedback is in good agreement with the experimental results for the size and shape of the domain of control. (c) 1997 American Institute of Physics. PMID:12779682

  15. One-dimensional non-LTE time-dependent radiative transfer of an He-detonation model and the connection to faint and fast-decaying supernovae

    NASA Astrophysics Data System (ADS)

    Dessart, Luc; Hillier, D. John

    2015-02-01

    We present non-LTE (non-Local-Thermodynamic-Equilibrium) time-dependent radiative transfer simulations for ejecta produced by the detonation of a helium shell at the surface of a low-mass carbon/oxygen white dwarf (WD). This mechanism is one possible origin for supernovae (SNe) with faint and fast-decaying light curves, such as .Ia SNe and Ca-rich transients. Our initial ejecta conditions at 1 d are given by the 0.18 B explosion model COp45HEp2 of Waldman et al. The 0.2 M⊙ ejecta initially contains 0.11 M⊙ of He, 0.03 M⊙ of Ca, and 0.03 M⊙ of Ti. We obtain an ˜ 5 d rise to a bolometric maximum of 3.59 × 1041 erg s-1, primarily powered by 48V decay. Multi-band light curves show distinct morphologies, with a rise to maximum magnitude (-14.3 to -16.7 mag) that varies between 3 to 9 d from the U to the K bands. Near-IR light curves show no secondary maximum. Because of the presence of both He I and Si II lines at early times we obtain a hybrid Type Ia/Ib classification. During the photospheric phase line blanketing is caused primarily by Ti II. At nebular times, the spectra show strong Ca II lines in the optical (but no [O I] 6300-6364 Å emission), and Ti II in the near-IR. Overall, these results match qualitatively the very disparate properties of .Ia SNe and Ca-rich transients. Although the strong Ti II blanketing and red colours that we predict are rarely observed, they are seen, for example, in OGLE-2013- SN-079. Furthermore, we obtain a faster light-curve evolution than, for example, PTF10iuv, indicating an ejecta mass >0.2 M⊙. An alternate scenario may be the merger of two WDs, one or both composed of He.

  16. Fast X-Ray Timing: A Window into the Strong-Field Regime

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod

    2010-01-01

    The dynamical time-scales in the vicinity of neutron star surfaces and black hole horizons are in the millisecond range. Over the past decade, timing signatures on such scales, either quasi-periodic oscillations (QPOs) and/or coherent pulsations, have been discovered and studied from both neutron stars and black holes with NASA's Rossi X-ray Timing Explorer, Although theoretical interpretations are still hotly debated, these timing properties almost certainly reflect the dynamics of matter in regions dominated by relativistic gravity. I will survey our current understanding of these timing properties, with a focus on how they might he used as probes of fundamental physics.

  17. Structural Theories and Race-Specific Drug Arrests: What Structural Factors Account for the Rise in Race-Specific Drug Arrests over Time?

    ERIC Educational Resources Information Center

    Parker, Karen F.; Maggard, Scott R.

    2005-01-01

    Studies examining the structural correlates of urban crime have generated a large body of research; however, few studies have linked the structural conditions to race-specific drug arrests. In this study, the authors examine the impact of urban disadvantage, social disorganization, and racial threat indicators on the rise in race-specific drug…

  18. Fast Diffusion to Self-Similarity: Complete Spectrum, Long-Time Asymptotics, and Numerology

    NASA Astrophysics Data System (ADS)

    Denzler, Jochen; McCann, Robert J.

    2005-03-01

    The complete spectrum is determined for the operator on the Sobolev space W1,2ρ(Rn) formed by closing the smooth functions of compact support with respect to the norm Here the Barenblatt profile ρ is the stationary attractor of the rescaled diffusion equation in the fast, supercritical regime m the same diffusion dynamics represent the steepest descent down an entropy E(u) on probability measures with respect to the Wasserstein distance d2. Formally, the operator H=HessρE is the Hessian of this entropy at its minimum ρ, so the spectral gap H≧α:=2-n(1-m) found below suggests the sharp rate of asymptotic convergence: from any centered initial data 0≦u(0,x) ∈ L1(Rn) with second moments. This bound improves various results in the literature, and suggests the conjecture that the self-similar solution u(t,x)=R(t)-nρ(x/R(t)) is always slowest to converge. The higher eigenfunctions which are polynomials with hypergeometric radial parts and the presence of continuous spectrum yield additional insight into the relations between symmetries of Rn and the flow. Thus the rate of convergence can be improved if we are willing to replace the distance to ρ with the distance to its nearest mass-preserving dilation (or still better, affine image). The strange numerology of the spectrum is explained in terms of the number of moments of ρ.

  19. Real-time 2D floating-point fast Fourier transforms for seeker simulation

    NASA Astrophysics Data System (ADS)

    Chamberlain, Richard; Lord, Eric; Shand, David J.

    2002-07-01

    The floating point Fast Fourier Transform (FFT) is one of the most useful basic functions available to the image and signal processing engineer allowing many complex and detailed special functions to be implemented more simply in the frequency domain. In the Hardware-in-the-Loop field an image transformed using FFT would allow the designer to think about accurate frequency based simulation of seeker lens effects, motion blur, detector transfer functions and much more. Unfortunately, the transform requires many hundreds of thousands or millions of floating point operations on a single modest sized image making it impractical for realtime Hardware-in-the-Loop systems. .until now. This paper outlines the development, by Nallatech, of an FPGA based IEEE floating point core. It traces the subsequent use of this core to develop a full 256 X 256 FFT and filter process implemented on COTS hardware at frame rates up to 150Hz. This transform can be demonstrated to model optical transfer functions at a far greater accuracy than the current spatial models. Other applications and extensions of this technique will be discussed such as filtering for image tracking algorithms and in the simulation of radar processing in the frequency domain.

  20. Improved target detection and bearing estimation utilizing fast orthogonal search for real-time spectral analysis

    NASA Astrophysics Data System (ADS)

    Osman, Abdalla; Nourledin, Aboelamgd; El-Sheimy, Naser; Theriault, Jim; Campbell, Scott

    2009-06-01

    The problem of target detection and tracking in the ocean environment has attracted considerable attention due to its importance in military and civilian applications. Sonobuoys are one of the capable passive sonar systems used in underwater target detection. Target detection and bearing estimation are mainly obtained through spectral analysis of received signals. The frequency resolution introduced by current techniques is limited which affects the accuracy of target detection and bearing estimation at a relatively low signal-to-noise ratio (SNR). This research investigates the development of a bearing estimation method using fast orthogonal search (FOS) for enhanced spectral estimation. FOS is employed in this research in order to improve both target detection and bearing estimation in the case of low SNR inputs. The proposed methods were tested using simulated data developed for two different scenarios under different underwater environmental conditions. The results show that the proposed method is capable of enhancing the accuracy for target detection as well as bearing estimation especially in cases of a very low SNR.

  1. Rising Sea Levels: Truth or Scare?

    ERIC Educational Resources Information Center

    Peacock, Alan

    2007-01-01

    When "ITV News" ran an item that shocked the author, about rising sea levels that will have caused the entire evacuation of the islands by the end of this year, he began to wonder whether the Pacific Ocean is really rising as fast as this. The media reporting of such things can be a double-edged sword. On the one hand, it brought to the author's…

  2. A double-threshold technique for fast time-correspondence imaging

    NASA Astrophysics Data System (ADS)

    Li, Ming-Fei; Zhang, Yu-Ran; Liu, Xue-Feng; Yao, Xu-Ri; Luo, Kai-Hong; Fan, Heng; Wu, Ling-An

    2013-11-01

    We present a robust imaging method based on time-correspondence imaging and normalized ghost imaging (GI) that sets two thresholds to select the reference frame exposures for image reconstruction. This double-threshold time-correspondence imaging protocol always gives better quality and signal-to-noise ratio than previous GI schemes, and is insensitive to surrounding noise. Moreover, only simple add and minus operations are required while less data storage space and computing time are consumed; thus, faster imaging speeds are attainable. The protocol offers a general approach applicable to all GI techniques and marks a further step forward towards real-time practical applications of correlation imaging.

  3. Study of bi-alkali photocathode growth on glass by X-ray techniques for fast timing response photomultipliers

    NASA Astrophysics Data System (ADS)

    Xie, Junqi; Demarteau, Marcel; Wagner, Robert; Ruiz-Oses, Miguel; Liang, Xue; Ben-Zvi, Ilan; Attenkofer, Klaus; Schubert, Susanne; Smedley, John; Wong, Jared; Padmore, Howard; Woll, Arthur

    2014-03-01

    Bi-alkali antimonide photocathode is an essential component in fast timing response photomultipliers. Real-time in-situ grazing incidence x-ray diffraction and post-growth x-ray reflectivity measurement were performed to study the photocathode deposition process on glass substrate. Grazing incidence x-ray diffraction patterns show the formation of Sb crystalline, dissolution of crystalline phase Sb by the application of K vapor and reformation of refined crystal textures. XRR result exhibits that the film thickness increases ~ 4.5 times after K diffusion and almost have no change after Cs diffusion. Further investigation is expected to understand the photocathode growth process and provide guidelines for photocathode development.

  4. Constraints of relic gravitational waves by pulsar timing arrays: Forecasts for the FAST and SKA projects

    NASA Astrophysics Data System (ADS)

    Zhao, Wen; Zhang, Yang; You, Xiao-Peng; Zhu, Zong-Hong

    2013-06-01

    Measurement of pulsar timing residuals provides a direct way to detect relic gravitational waves at the frequency f˜1/yr. In this paper, we investigate the constraints on the inflationary parameters, the tensor-to-scalar ratio r, and the tensor spectral index nt, by the current and future pulsar timing arrays. We find that the Five-hundred-meter Aperture Spherical Radio Telescope in China and the planned Square Kilometre Array projects have fairly strong abilities to test the phantomlike inflationary models. If r=0.1, then Five-hundred-meter Aperture Spherical Radio Telescope could give the constraint on the spectral index nt<0.56 and Square Kilometre Array could give nt<0.32, while an observation with total time T=20yr, pulsar noise level σw=30ns, and monitored pulsar number n=200 could even constrain nt<0.07. These are much tighter than those inferred from the current results of the Parkes Pulsar Timing Array, European Pulsar Timing Array, and North American Nanohertz Observatory for Gravitational Waves. By studying the effects of various observational factors on the sensitivities of pulsar timing arrays, we find that compared with σw and n, the total observation time T has the most significant effect.

  5. Fast interactive real-time volume rendering of real-time three-dimensional echocardiography: an implementation for low-end computers

    NASA Technical Reports Server (NTRS)

    Saracino, G.; Greenberg, N. L.; Shiota, T.; Corsi, C.; Lamberti, C.; Thomas, J. D.

    2002-01-01

    Real-time three-dimensional echocardiography (RT3DE) is an innovative cardiac imaging modality. However, partly due to lack of user-friendly software, RT3DE has not been widely accepted as a clinical tool. The object of this study was to develop and implement a fast and interactive volume renderer of RT3DE datasets designed for a clinical environment where speed and simplicity are not secondary to accuracy. Thirty-six patients (20 regurgitation, 8 normal, 8 cardiomyopathy) were imaged using RT3DE. Using our newly developed software, all 3D data sets were rendered in real-time throughout the cardiac cycle and assessment of cardiac function and pathology was performed for each case. The real-time interactive volume visualization system is user friendly and instantly provides consistent and reliable 3D images without expensive workstations or dedicated hardware. We believe that this novel tool can be used clinically for dynamic visualization of cardiac anatomy.

  6. Fast Numerical Evaluation of Time-Derivative Nonadiabatic Couplings for Mixed Quantum-Classical Methods.

    PubMed

    Ryabinkin, Ilya G; Nagesh, Jayashree; Izmaylov, Artur F

    2015-11-01

    We have developed a numerical differentiation scheme that eliminates evaluation of overlap determinants in calculating the time-derivative nonadiabatic couplings (TDNACs). Evaluation of these determinants was the bottleneck in previous implementations of mixed quantum-classical methods using numerical differentiation of electronic wave functions in the Slater determinant representation. The central idea of our approach is, first, to reduce the analytic time derivatives of Slater determinants to time derivatives of molecular orbitals and then to apply a finite-difference formula. Benchmark calculations prove the efficiency of the proposed scheme showing impressive several-order-of-magnitude speedups of the TDNAC calculation step for midsize molecules. PMID:26538034

  7. Ground potential rise monitor

    DOEpatents

    Allen, Zachery W.; Zevenbergen, Gary A.

    2012-04-03

    A device and method for detecting ground potential rise (GPR) comprising positioning a first electrode and a second electrode at a distance from each other into the earth. The voltage of the first electrode and second electrode is attenuated by an attenuation factor creating an attenuated voltage. The true RMS voltage of the attenuated voltage is determined creating an attenuated true RMS voltage. The attenuated true RMS voltage is then multiplied by the attenuation factor creating a calculated true RMS voltage. If the calculated true RMS voltage is greater than a first predetermined voltage threshold, a first alarm is enabled at a local location. If user input is received at a remote location acknowledging the first alarm, a first alarm acknowledgment signal is transmitted. The first alarm acknowledgment signal is then received at which time the first alarm is disabled.

  8. Reduction of the fast electrons preheating by changing the spike launch time in shock ignition approach

    NASA Astrophysics Data System (ADS)

    Jafar Jafari, Mohammad; Farahbod, Amir Hossein; Rezaei, Somayeh

    2016-01-01

    Target characteristic parameters in shock ignition approach before launching the spike pulse are studied using a 1-D hydrodynamic simulation code. By delaying the spike launch time, the shell areal density, ρR, is increased. The enhanced shell areal density prevents the hot electrons preheating of main fuel which in turn is generated from the intense laser plasma interaction with corona. To consider the effect of the spike launch time on the target performance, the target gain for a wide range of spike powers and launch times are computed. It is noticed that for HiPER reference target, few tenth nanoseconds displacement of spike launch time increases the areal density, ρR, value up to 30-70 percent. Furthermore, by choosing an appropriate spike energy and peak power, the optimum target gain is achieved in which the total driver energy is reduced.

  9. Characterization of compounds by time-of-flight measurement utilizing random fast ions

    DOEpatents

    Conzemius, Robert J.

    1989-01-01

    An apparatus for characterizing the mass of sample and daughter particles, comprising a source for providing sample ions; a fragmentation region wherein a fraction of the sample ions may fragment to produce daughter ion particles; an electrostatic field region held at a voltage level sufficient to effect ion-neutral separation and ion-ion separation of fragments from the same sample ion and to separate ions of different kinetic energy; a detector system for measuring the relative arrival times of particles; and processing means operatively connected to the detector system to receive and store the relative arrival times and operable to compare the arrival times with times detected at the detector when the electrostatic field region is held at a different voltage level and to thereafter characterize the particles. Sample and daughter particles are characterized with respect to mass and other characteristics by detecting at a particle detector the relative time of arrival for fragments of a sample ion at two different electrostatic voltage levels. The two sets of particle arrival times are used in conjunction with the known altered voltage levels to mathematically characterize the sample and daughter fragments. In an alternative embodiment the present invention may be used as a detector for a conventional mass spectrometer. In this embodiment, conventional mass spectrometry analysis is enhanced due to further mass resolving of the detected ions.

  10. Characterization of compounds by time-of-flight measurement utilizing random fast ions

    DOEpatents

    Conzemius, R.J.

    1989-04-04

    An apparatus is described for characterizing the mass of sample and daughter particles, comprising a source for providing sample ions; a fragmentation region wherein a fraction of the sample ions may fragment to produce daughter ion particles; an electrostatic field region held at a voltage level sufficient to effect ion-neutral separation and ion-ion separation of fragments from the same sample ion and to separate ions of different kinetic energy; a detector system for measuring the relative arrival times of particles; and processing means operatively connected to the detector system to receive and store the relative arrival times and operable to compare the arrival times with times detected at the detector when the electrostatic field region is held at a different voltage level and to thereafter characterize the particles. Sample and daughter particles are characterized with respect to mass and other characteristics by detecting at a particle detector the relative time of arrival for fragments of a sample ion at two different electrostatic voltage levels. The two sets of particle arrival times are used in conjunction with the known altered voltage levels to mathematically characterize the sample and daughter fragments. In an alternative embodiment the present invention may be used as a detector for a conventional mass spectrometer. In this embodiment, conventional mass spectrometry analysis is enhanced due to further mass resolving of the detected ions. 8 figs.

  11. Time-resolved spectroscopy using a chopper wheel as a fast shutter

    SciTech Connect

    Wang, Shicong; Wendt, Amy E.; Boffard, John B.; Lin, Chun C.

    2015-01-15

    Widely available, small form-factor, fiber-coupled spectrometers typically have a minimum exposure time measured in milliseconds, and thus cannot be used directly for time-resolved measurements at the microsecond level. Spectroscopy at these faster time scales is typically done with an intensified charge coupled device (CCD) system where the image intensifier acts as a “fast” electronic shutter for the slower CCD array. In this paper, we describe simple modifications to a commercially available chopper wheel system to allow it to be used as a “fast” mechanical shutter for gating a fiber-coupled spectrometer to achieve microsecond-scale time-resolved optical measurements of a periodically pulsed light source. With the chopper wheel synchronized to the pulsing of the light source, the time resolution can be set to a small fraction of the pulse period by using a chopper wheel with narrow slots separated by wide spokes. Different methods of synchronizing the chopper wheel and pulsing of the light sources are explored. The capability of the chopper wheel system is illustrated with time-resolved measurements of pulsed plasmas.

  12. Method of signal detection from silicon photomultipliers using fully differential Charge to Time Converter and fast shaper

    NASA Astrophysics Data System (ADS)

    Baszczyk, M.; Dorosz, P.; Glab, S.; Kucewicz, W.; Mik, L.; Sapor, M.

    2016-07-01

    The paper presents an implementation of fully differential readout method for Silicon Photomultipliers (SiPM). Front-end electronics consists of a fast and slow path. The former creates the trigger signal while the latter produces a pulse of width proportional to the input charge. The fast shaper generates unipolar pulse and utilizes the pole-zero cancelation circuit. The peaking time for single photoelectron is equal to 3.6 ns and the FWHM is 3.8 ns. The pulse width of the Charge to Time Converter (QTC) depends on the number of photons entering the SiPM at the moment of measurement. The QTC response is nonlinear but it allows us to work with signals in a wide dynamic range. The proposed readout method is effective in measurements of random signals where frequent events tend to pile-up. Thermal generation and afterpulses have a strong influence on the width of pulses from QTC. The proposed method enables us to distinguish those overlapping signals and get the reliable information on the number of detected photons.

  13. CauseMap: fast inference of causality from complex time series.

    PubMed

    Maher, M Cyrus; Hernandez, Ryan D

    2015-01-01

    Background. Establishing health-related causal relationships is a central pursuit in biomedical research. Yet, the interdependent non-linearity of biological systems renders causal dynamics laborious and at times impractical to disentangle. This pursuit is further impeded by the dearth of time series that are sufficiently long to observe and understand recurrent patterns of flux. However, as data generation costs plummet and technologies like wearable devices democratize data collection, we anticipate a coming surge in the availability of biomedically-relevant time series data. Given the life-saving potential of these burgeoning resources, it is critical to invest in the development of open source software tools that are capable of drawing meaningful insight from vast amounts of time series data. Results. Here we present CauseMap, the first open source implementation of convergent cross mapping (CCM), a method for establishing causality from long time series data (≳25 observations). Compared to existing time series methods, CCM has the advantage of being model-free and robust to unmeasured confounding that could otherwise induce spurious associations. CCM builds on Takens' Theorem, a well-established result from dynamical systems theory that requires only mild assumptions. This theorem allows us to reconstruct high dimensional system dynamics using a time series of only a single variable. These reconstructions can be thought of as shadows of the true causal system. If reconstructed shadows can predict points from opposing time series, we can infer that the corresponding variables are providing views of the same causal system, and so are causally related. Unlike traditional metrics, this test can establish the directionality of causation, even in the presence of feedback loops. Furthermore, since CCM can extract causal relationships from times series of, e.g., a single individual, it may be a valuable tool to personalized medicine. We implement CCM in Julia, a

  14. A New Characteristic Function for Fast Time-Reverse Seismic Event Location

    NASA Astrophysics Data System (ADS)

    Hendriyana, Andri; Bauer, Klaus; Weber, Michael; Jaya, Makky; Muksin, Muksin

    2015-04-01

    Microseismicity produced by natural activities is usually characterized by low signal-to-noise ratio and huge amount of data as recording is conducted for a long period of time. Locating microseismic events is preferably carried out using migration-based methods such as time-reverse modeling (TRM). The original TRM is based on backpropagating the wavefield from the receiver down to the source location. Alternatively, we are using a characteristic function (CF) derived from the measured wavefield as input for the TRM. The motivation for such a strategy is to avoid undesired contributions from secondary arrivals which may generate artifacts in the final images. In this presentation, we introduce a new CF as input for TRM method. To obtain this CF, initially we apply kurtosis-based automatic onset detection and convolution with a given wavelet. The convolution with low frequency wavelets allows us to conduct time-reverse modeling using coarser sampling hence it will reduce computing time. We apply the method to locate seismic events measured along an active part of the Sumatra Fault around the Tarutung pull-apart basin (North Sumatra, Indonesia). The results show that seismic events are well-determined since they are concentrated along the Sumatran fault. Internal details of the Tarutung basin structure could be derived. Our results are consistent with those obtained from inversion of manually picked travel time data.

  15. Short time Fourier analysis of the electromyogram - Fast movements and constant contraction

    NASA Technical Reports Server (NTRS)

    Hannaford, Blake; Lehman, Steven

    1986-01-01

    Short-time Fourier analysis was applied to surface electromyograms (EMG) recorded during rapid movements, and during isometric contractions at constant forces. A portion of the data to be transformed by multiplying the signal by a Hamming window was selected, and then the discrete Fourier transform was computed. Shifting the window along the data record, a new spectrum was computed each 10 ms. The transformed data were displayed in spectograms or 'voiceprints'. This short-time technique made it possible to see time-dependencies in the EMG that are normally averaged in the Fourier analysis of these signals. Spectra of EMGs during isometric contractions at constant force vary in the short (10-20 ms) term. Short-time spectra from EMGs recorded during rapid movements were much less variable. The windowing technique picked out the typical 'three-burst pattern' in EMG's from both wrist and head movements. Spectra during the bursts were more consistent than those during isometric contractions. Furthermore, there was a consistent shift in spectral statistics in the course of the three bursts. Both the center frequency and the variance of the spectral energy distribution grew from the first burst to the second burst in the same muscle. The analogy between EMGs and speech signals is extended to argue for future applicability of short-time spectral analysis of EMG.

  16. A fast and Robust Algorithm for general inequality/equality constrained minimum time problems

    SciTech Connect

    Briessen, B.; Sadegh, N.

    1995-12-01

    This paper presents a new algorithm for solving general inequality/equality constrained minimum time problems. The algorithm`s solution time is linear in the number of Runge-Kutta steps and the number of parameters used to discretize the control input history. The method is being applied to a three link redundant robotic arm with torque bounds, joint angle bounds, and a specified tip path. It solves case after case within a graphical user interface in which the user chooses the initial joint angles and the tip path with a mouse. Solve times are from 30 to 120 seconds on a Hewlett Packard workstation. A zero torque history is always used in the initial guess, and the algorithm has never crashed, indicating its robustness. The algorithm solves for a feasible solution for large trajectory execution time t{sub f} and then reduces t{sub f} and then reduces t{sub f} by a small amount and re-solves. The fixed time re- solve uses a new method of finding a near-minimum-2-norm solution to a set of linear equations and inequalities that achieves quadratic convegence to a feasible solution of the full nonlinear problem.

  17. The generalized centroid difference method for picosecond sensitive determination of lifetimes of nuclear excited states using large fast-timing arrays

    NASA Astrophysics Data System (ADS)

    Régis, J.-M.; Mach, H.; Simpson, G. S.; Jolie, J.; Pascovici, G.; Saed-Samii, N.; Warr, N.; Bruce, A.; Degenkolb, J.; Fraile, L. M.; Fransen, C.; Ghita, D. G.; Kisyov, S.; Koester, U.; Korgul, A.; Lalkovski, S.; Mărginean, N.; Mutti, P.; Olaizola, B.; Podolyak, Z.; Regan, P. H.; Roberts, O. J.; Rudigier, M.; Stroe, L.; Urban, W.; Wilmsen, D.

    2013-10-01

    A novel method for direct electronic “fast-timing” lifetime measurements of nuclear excited states via γ-γ coincidences using an array equipped with N∈N equally shaped very fast high-resolution LaBr3(Ce) scintillator detectors is presented. Analogous to the mirror symmetric centroid difference method, the generalized centroid difference method provides two independent “start” and “stop” time spectra obtained by a superposition of the N(N-1)γ-γ time difference spectra of the N detector fast-timing system. The two fast-timing array time spectra correspond to a forward and reverse gating of a specific γ-γ cascade. Provided that the energy response and the electronic time pick-off of the detectors are almost equal, a mean prompt response difference between start and stop events is calibrated and used as a single correction for lifetime determination. These combined fast-timing arrays mean γ-γ time-walk characteristics can be determined for 40 keVfast-timing array delivered an absolute time resolving power of 3 ps for 10 000 γ-γ events per total fast timing array start and stop time spectrum. The new method is tested over the total dynamic range by the measurements of known picosecond lifetimes in standard γ-ray sources.

  18. Application of the G-JF discrete-time thermostat for fast and accurate molecular simulations

    NASA Astrophysics Data System (ADS)

    Grønbech-Jensen, Niels; Hayre, Natha Robert; Farago, Oded

    2014-02-01

    A new Langevin-Verlet thermostat that preserves the fluctuation-dissipation relationship for discrete time steps is applied to molecular modeling and tested against several popular suites (AMBER, GROMACS, LAMMPS) using a small molecule as an example that can be easily simulated by all three packages. Contrary to existing methods, the new thermostat exhibits no detectable changes in the sampling statistics as the time step is varied in the entire numerical stability range. The simple form of the method, which we express in the three common forms (Velocity-Explicit, Störmer-Verlet, and Leap-Frog), allows for easy implementation within existing molecular simulation packages to achieve faster and more accurate results with no cost in either computing time or programming complexity.

  19. Enabling fast, stable and accurate peridynamic computations using multi-time-step integration

    DOE PAGESBeta

    Lindsay, P.; Parks, M. L.; Prakash, A.

    2016-04-13

    Peridynamics is a nonlocal extension of classical continuum mechanics that is well-suited for solving problems with discontinuities such as cracks. This paper extends the peridynamic formulation to decompose a problem domain into a number of smaller overlapping subdomains and to enable the use of different time steps in different subdomains. This approach allows regions of interest to be isolated and solved at a small time step for increased accuracy while the rest of the problem domain can be solved at a larger time step for greater computational efficiency. Lastly, performance of the proposed method in terms of stability, accuracy, andmore » computational cost is examined and several numerical examples are presented to corroborate the findings.« less

  20. Fast time-correlated multi-element photon detector and method

    DOEpatents

    Hayden, Carl C.; Chandler, David W.; Luong, A. Khai

    2007-12-18

    Photons emitted from a sample responsive to being excited by laser pulses are directed through a prism onto a photomultiplier tube having several spaced-apart anodes. The prism alters the path of each photon as a function of its wavelength so that the wavelength determines the anode to which the photon is directed. Taps of first and second delay lines that are coupled to respective alternating anodes. When an anode receives the photon, it generates a pulse that propagates through the delay line in opposite directions from its associated tap. A timer determines first and second times from the laser pulse to the pulse reaching the first and second ends of the delay line. The difference between the first and second times corresponds to the wavelength of the emitted photon and the sum of the first and second times corresponds to the emission delay of the emitted photon.

  1. Fast evaluation of a time-domain non-linear cochlear model on GPUs

    NASA Astrophysics Data System (ADS)

    Sabo, Doron; Barzelay, Oded; Weiss, Shlomo; Furst, Miriam

    2014-05-01

    We present a parallel algorithm that solves a time-domain non-linear mathematical model of the cochlea. The previously known serial solution of the cochlear model is based on LU decomposition in the longitudinal dimension and is iterative in the time dimension. These two characteristics of the serial solution limit parallelism and prevent efficient computations on a massively parallel processor. We introduce a novel parallel algorithm that successfully overcomes the challenges posed by the cochlear model. We present performance results of a parallel implementation of the algorithm that shortens the computation time by a typical factor of 160-180, which makes the proposed algorithm of practical value for applications such as clinical audiological diagnosis.

  2. The rising risks of rising tides

    SciTech Connect

    Hanson, H.; Lindh, G.

    1996-12-31

    The erosion of beaches, flooding of agricultural land, and intrusion of saltwater into coastal streams could become a reality if temperatures climb. Over the past century, sea levels have risen 4 to 6 inches. Now, the Intergovernmental panel on Climate Change (IPCC) predicts that sea levels will rise between 8 and 28 inches by 2070, say Hans Hanson, associate professor emeritus in the Department of Water Resources Engineering at the University of Lund in Sweden. Coastal communities, which harbor more than half the world`s population, are poorly equipped to combat the threat of encroaching waters. {open_quotes}Few public officials have developed comprehensive strategies to address the potential consequences of sea-level rise,{close_quotes} the authors say. In response to the lack of long-term strategies to address the potential consequences of sea-level rise,{close_quotes} the authors say. In response to the lack of long-term strategies, the IPCC has recommended that coastal nations implement coastal-zone management plans by 2000. {open_quotes}Low-lying islands and high-use, developed coastal areas... face an urgent need to develop strategies for coping with sea-level rise,{close_quotes} the authors conclude.

  3. Fast Identification of 1,3-Dimethylamylamine Using Direct Analysis in Real Time-QToF-MS.

    PubMed

    Avula, Bharathi; Smillie, Troy J; Wang, Yan-Hong; Zweigenbaum, Jerry; ElSohly, Mahmoud A; Khan, Ikhlas A

    2015-01-01

    The central nervous system stimulant 1,3-dimethylamylamine (DMAA) has been found in preworkout products and dietary supplements. A fast direct analysis in real time-quadrupole time of flight-MS method was used for identification of DMAA in dietary supplements and to determine if this compound is present in geranium (Pelargonium graveolens) plants or oil. This method involved the use of [M+H]+ ions in the positive mode based on the exact mass of DMAA. The results of this investigation showed that DMAA was not detected from authentic samples of P. graveolens plant material or pelargonium oil or in multiple samples of commercially available pelargonium oil. DMAA was detected in three samples of dietary supplements. The LOD of DMAA was found to be 10 ng/mL. PMID:26086254

  4. Time-dependent calculations of transfer ionization by fast proton-helium collision in one-dimensional kinematics

    NASA Astrophysics Data System (ADS)

    Serov, Vladislav V.; Kheifets, A. S.

    2014-12-01

    We analyze a transfer ionization (TI) reaction in the fast proton-helium collision H++He →H0+He2 ++ e- by solving a time-dependent Schrödinger equation (TDSE) under the classical projectile motion approximation in one-dimensional kinematics. In addition, we construct various time-independent analogs of our model using lowest-order perturbation theory in the form of the Born series. By comparing various aspects of the TDSE and the Born series calculations, we conclude that the recent discrepancies of experimental and theoretical data may be attributed to deficiency of the Born models used by other authors. We demonstrate that the correct Born series for TI should include the momentum-space overlap between the double-ionization amplitude and the wave function of the transferred electron.

  5. Antiferroelectric Thin-Film Capacitors with High Energy-Storage Densities, Low Energy Losses, and Fast Discharge Times.

    PubMed

    Ahn, Chang Won; Amarsanaa, Gantsooj; Won, Sung Sik; Chae, Song A; Lee, Dae Su; Kim, Ill Won

    2015-12-01

    We demonstrate a capacitor with high energy densities, low energy losses, fast discharge times, and high temperature stabilities, based on Pb(0.97)Y(0.02)[(Zr(0.6)Sn(0.4))(0.925)Ti(0.075)]O3 (PYZST) antiferroelectric thin-films. PYZST thin-films exhibited a high recoverable energy density of U(reco) = 21.0 J/cm(3) with a high energy-storage efficiency of η = 91.9% under an electric field of 1300 kV/cm, providing faster microsecond discharge times than those of commercial polypropylene capacitors. Moreover, PYZST thin-films exhibited high temperature stabilities with regard to their energy-storage properties over temperatures ranging from room temperature to 100 °C and also exhibited strong charge-discharge fatigue endurance up to 1 × 10(7) cycles. PMID:26606502

  6. Practical and fast quantum random number generation based on photon arrival time relative to external reference

    SciTech Connect

    Nie, You-Qi; Zhang, Jun Pan, Jian-Wei; Zhang, Hong-Fei; Wang, Jian; Zhang, Zhen; Ma, Xiongfeng

    2014-02-03

    We present a practical high-speed quantum random number generator, where the timing of single-photon detection relative to an external time reference is measured as the raw data. The bias of the raw data can be substantially reduced compared with the previous realizations. The raw random bit rate of our generator can reach 109 Mbps. We develop a model for the generator and evaluate the min-entropy of the raw data. Toeplitz matrix hashing is applied for randomness extraction, after which the final random bits are able to pass the standard randomness tests.

  7. Toward Fast Calibration of Global Drift in Scanning Electron Microscopes with Respect to Time and Magnification

    NASA Astrophysics Data System (ADS)

    Malti, Abed C.; Dembélé, Sounkalo; Piat, Nadine; Arnoult, Claire; Marturi, Naresh

    2012-01-01

    It is a well-known fact that scanning electron microscopic (SEM) image acquisition is mainly affected by nonlinearities and instabilities of the column and probe-specimen interaction; in turn, producing a shift in the image points with respect to many parameters and time, in particular. Even though this drift is comparatively less in modern SEMs, it is still an important factor to consider in most of the SEM-based applications. In this airticle, a simple and real-time method is proposed to estimate the global drift from a set of target images using image phase correlation, and to model its evolution by using the recursive equations of time and magnification. Based on the developed model, it is opted to use a Kalman filter in real time for accurate estimation and removal of the drift from the images. The developed method is tested using the images from a tungsten filament gun SEM (Jeol JSM 820) and a field effect gun SEM (FEI Quanta 200). The derived results show the effectiveness of the developed algorithm and also demonstrates its ability to be used in robotics as well as in material characterization under SEM.

  8. FAST TRACK COMMUNICATION Time-dependent exact solutions of the nonlinear Kompaneets equation

    NASA Astrophysics Data System (ADS)

    Ibragimov, N. H.

    2010-12-01

    Time-dependent exact solutions of the Kompaneets photon diffusion equation are obtained for several approximations of this equation. One of the approximations describes the case when the induced scattering is dominant. In this case, the Kompaneets equation has an additional symmetry which is used for constructing some exact solutions as group invariant solutions.

  9. Experts in Fast-Ball Sports Reduce Anticipation Timing Cost by Developing Inhibitory Control

    ERIC Educational Resources Information Center

    Nakamoto, Hiroki; Mori, Shiro

    2012-01-01

    The present study was conducted to examine the relationship between expertise in movement correction and rate of movement reprogramming within limited time periods, and to clarify the specific cognitive processes regarding superior reprogramming ability in experts. Event-related potentials (ERPs) were recorded in baseball experts (n = 7) and…

  10. Fast rise of 'Neptune-size' planets (4-8 R {sub ⊕}) from P ∼ 10 to ∼250 days—statistics of Kepler planet candidates up to ∼0.75 au

    SciTech Connect

    Dong, Subo; Zhu, Zhaohuan

    2013-11-20

    We infer the period (P) and size (R{sub p} ) distribution of Kepler transiting planet candidates with R{sub p} ≥ 1 R {sub ⊕} and P < 250 days hosted by solar-type stars. The planet detection efficiency is computed by using measured noise and the observed time spans of the light curves for ∼120,000 Kepler target stars. We focus on deriving the shape of planet periods and radius distribution functions. We find that for orbital periods P > 10 days, the planet frequency dN{sub p} /dlog P for 'Neptune-size' planets (R{sub p} = 4-8 R {sub ⊕}) increases with period as ∝P {sup 0.7±0.1}. In contrast, dN{sub p} /dlog P for 'super-Earth-size' (2-4 R {sub ⊕}) as well as 'Earth-size' (1-2 R {sub ⊕}) planets are consistent with a nearly flat distribution as a function of period (∝P {sup 0.11±0.05} and ∝P {sup –0.10±0.12}, respectively), and the normalizations are remarkably similar (within a factor of ∼1.5 at 50 days). Planet size distribution evolves with period, and generally the relative fractions for big planets (∼3-10 R {sub ⊕}) increase with period. The shape of the distribution function is not sensitive to changes in the selection criteria of the sample. The implied nearly flat or rising planet frequency at long periods appears to be in disagreement with the sharp decline at ∼100 days in planet frequency for low-mass planets (planet mass m{sub p} < 30 M {sub ⊕}) recently suggested by the HARPS survey. Within 250 days, the cumulative frequencies for Earth-size and super-Earth-size planets are remarkably similar (∼28% and 25%), while Neptune-size and Jupiter-size planets are ∼7% and ∼3%, respectively. A major potential uncertainty arises from the unphysical impact parameter distribution of the candidates.

  11. On fast computation of finite-time coherent sets using radial basis functions

    NASA Astrophysics Data System (ADS)

    Froyland, Gary; Junge, Oliver

    2015-08-01

    Finite-time coherent sets inhibit mixing over finite times. The most expensive part of the transfer operator approach to detecting coherent sets is the construction of the operator itself. We present a numerical method based on radial basis function collocation and apply it to a recent transfer operator construction [G. Froyland, "Dynamic isoperimetry and the geometry of Lagrangian coherent structures," Nonlinearity (unpublished); preprint arXiv:1411.7186] that has been designed specifically for purely advective dynamics. The construction [G. Froyland, "Dynamic isoperimetry and the geometry of Lagrangian coherent structures," Nonlinearity (unpublished); preprint arXiv:1411.7186] is based on a "dynamic" Laplace operator and minimises the boundary size of the coherent sets relative to their volume. The main advantage of our new approach is a substantial reduction in the number of Lagrangian trajectories that need to be computed, leading to large speedups in the transfer operator analysis when this computation is costly.

  12. On fast computation of finite-time coherent sets using radial basis functions.

    PubMed

    Froyland, Gary; Junge, Oliver

    2015-08-01

    Finite-time coherent sets inhibit mixing over finite times. The most expensive part of the transfer operator approach to detecting coherent sets is the construction of the operator itself. We present a numerical method based on radial basis function collocation and apply it to a recent transfer operator construction [G. Froyland, "Dynamic isoperimetry and the geometry of Lagrangian coherent structures," Nonlinearity (unpublished); preprint arXiv:1411.7186] that has been designed specifically for purely advective dynamics. The construction [G. Froyland, "Dynamic isoperimetry and the geometry of Lagrangian coherent structures," Nonlinearity (unpublished); preprint arXiv:1411.7186] is based on a "dynamic" Laplace operator and minimises the boundary size of the coherent sets relative to their volume. The main advantage of our new approach is a substantial reduction in the number of Lagrangian trajectories that need to be computed, leading to large speedups in the transfer operator analysis when this computation is costly. PMID:26328580

  13. Scintillating fibres coupled to silicon photomultiplier prototypes for fast beam monitoring and thin timing detectors

    NASA Astrophysics Data System (ADS)

    Papa, A.; Kettle, P.-R.; Ripiccini, E.; Rutar, G.

    2016-07-01

    Several scintillating fibre prototypes (single- and double-layers) made of 250 μm multi-clad square fibres coupled to silicon photomultiplier have been studied using electrons, positrons and muons at different energies. Current measurements show promising results: already for a single fibre layer and minimum ionizing particles we obtain a detection efficiency ≥ 95 % (mean collected light/fibre ≈ 8 phe), a timing resolution of 550 ps/fibre and a foreseen spatial resolution < 100 μm, based on the achieved negligible optical cross-talk between fibres (< 1 %). We will also discuss the performances of a double-layer staggered prototype configuration, for which a full detection efficiency (≥ 99 %) has been measured together with a timing resolution of ≈ 400 ps for double hit events.

  14. Fast processing of quantitative phase profiles from off-axis interferograms for real-time applications

    NASA Astrophysics Data System (ADS)

    Girshovitz, Pinhas; Shaked, Natan T.

    2015-03-01

    We review new and efficient algorithms, lately presented by us, for rapid reconstruction of quantitative phase maps from off-axis digital interferograms. These algorithms improve the conventional Fourier-based algorithm by using the Fourier transforms and the phase unwrapping process more efficiently, and thus decrease the calculation complexity required for extracting the sample phase map from the recorded interferograms. Using the new algorithms, on a standard personal computer without using the graphic processing-unit programming or parallel computing, we were able to speed up the processing and reach frame rates of up to 45 frames per second for one megapixel off-axis interferograms. These capabilities allow real-time visualization, calculation and data extraction for dynamic samples and processes, inspected by off-axis digital holography. Specific applications include biological cell imaging without labeling and real-time nondestructive testing.

  15. Fast time-domain diffuse optical tomography using pseudorandom bit sequences.

    PubMed

    Mo, Weirong; Chen, Nanguang

    2008-09-01

    We report a novel time-domain diffuse optical tomography to determine the optical properties in a faster speed than the conventional ones. Instead of using the ultrashort pulse laser, a 2.5 Gbps pseudorandom bit sequence is used to modulate the near-infrared light for tissue-like phantom illumination. The time-resolved signal can be retrieved very quickly by demodulation with the reference signal. The system impulse response has a full width at half maximum around 800 picoseconds and the 2-dimentional maps of optical properties can be obtained within a few seconds. The high signal-to-noise ratio and the environmental illumination insensitivity warrant a great potential for applications in clinical noninvasive breast cancer detection. PMID:18772975

  16. Experts in fast-ball sports reduce anticipation timing cost by developing inhibitory control.

    PubMed

    Nakamoto, Hiroki; Mori, Shiro

    2012-10-01

    The present study was conducted to examine the relationship between expertise in movement correction and rate of movement reprogramming within limited time periods, and to clarify the specific cognitive processes regarding superior reprogramming ability in experts. Event-related potentials (ERPs) were recorded in baseball experts (n=7) and novices (n=7) while they completed a predictive task. The task was to manually press a button to coincide with the arrival of a moving target. The target moved at a constant velocity, and its velocity was suddenly decreased in some trials. Under changed velocity conditions, the baseball experts showed significantly smaller timing errors and a higher rate of timing reprogramming than the novices. Moreover, ERPs in baseball experts revealed faster central negative deflection and augmented frontal positive deflection at 200ms (N200) and 300ms (Pd300) after target deceleration, respectively. Following this, peak latency of the next positive component in the central region (P300b) was delayed. The negative deflection at 200ms, augmented frontal positive deflection, and late positive deflection at 300ms have been interpreted as reflecting stimulus detection, motor inhibition, and stimulus-response translation processes. Taken together, these findings suggest that the experts have developed movement reprogramming to avoid anticipation cost, and this is characterized by quick detection of target velocity change, stronger inhibition of the planned, incorrect response, and update of the stimulus-response relationship in the changed environment. PMID:22626919

  17. Analysis of UAS DAA Surveillance in Fast-Time Simulations without DAA Mitigation

    NASA Technical Reports Server (NTRS)

    Thipphavong, David P.; Santiago, Confesor; Isaacson, David R.; Lee, Seung Man; Refai, Mohamad Said; Snow, James William

    2015-01-01

    Realization of the expected proliferation of Unmanned Aircraft System (UAS) operations in the National Airspace System (NAS) depends on the development and validation of performance standards for UAS Detect and Avoid (DAA) Systems. The RTCA Special Committee 228 is charged with leading the development of draft Minimum Operational Performance Standards (MOPS) for UAS DAA Systems. NASA, as a participating member of RTCA SC-228 is committed to supporting the development and validation of draft requirements for DAA surveillance system performance. A recent study conducted using NASA's ACES (Airspace Concept Evaluation System) simulation capability begins to address questions surrounding the development of draft MOPS for DAA surveillance systems. ACES simulations were conducted to study the performance of sensor systems proposed by the SC-228 DAA Surveillance sub-group. Analysis included but was not limited to: 1) number of intruders (both IFR and VFR) detected by all sensors as a function of UAS flight time, 2) number of intruders (both IFR and VFR) detected by radar alone as a function of UAS flight time, and 3) number of VFR intruders detected by all sensors as a function of UAS flight time. The results will be used by SC-228 to inform decisions about the surveillance standards of UAS DAA systems and future requirements development and validation efforts.

  18. Ultra fast miniaturized real-time PCR: 40 cycles in less than six minutes

    PubMed Central

    Neuzil, Pavel; Zhang, Chunyan; Pipper, Juergen; Oh, Sharon; Zhuo, Lang

    2006-01-01

    We have designed, fabricated and tested a real-time PCR chip capable of conducting one thermal cycle in 8.5 s. This corresponds to 40 cycles of PCR in 5 min and 40 s. The PCR system was made of silicon micromachined into the shape of a cantilever terminated with a disc. The thin film heater and a temperature sensor were placed on the disc perimeter. Due to the system's thermal constant of 0.27 s, we have achieved a heating rate of 175°C s−1 and a cooling rate of −125°C s−1. A PCR sample encapsulated with mineral oil was dispensed onto a glass cover slip placed on the silicon disc. The PCR cycle time was then determined by heat transfer through the glass, which took only 0.5 s. A real-time PCR sample with a volume of 100 nl was tested using a FAM probe. As the single PCR device occupied an area of only a few square millimeters, devices could be combined into a parallel system to increase throughput. PMID:16807313

  19. A fast mechanical shutter for submicrosecond time-resolved synchrotron experiments

    SciTech Connect

    Gembicky, Milan; Oss, Dan; Fuchs, Ryan; Coppens, Philip

    2010-07-19

    A new high-speed high-repetition-rate X-ray beam shutter for time-resolved photocrystallography at synchrotron sources has been developed and tested. The new design is based on a commercially existing DC servomotor and a frequency-lock control capable linear amplifier. Accurate speed control combined with an air bearing results in extremely low jitter in the motor rotation. Measured jitter at rotation speeds of 12,000 to 30,000 r min{sup -1} is less than 2 ns at a 6{sigma} confidence level. The chopper disc is interchangeable, allowing maximum flexibility. The chopper disc currently installed has 45 radial slots which allows synchronization from the 12th to the 20th subfrequencies of the orbit frequency of the Advanced Photon Source storage ring, corresponding to X-ray pulse frequencies of 13.6 to 22.6 kHz. At 30000 r min{sup -1} the opening time window with a 350 {micro}m slot size is 2.11 {micro}s, and correspondingly less with smaller openings, which may be compared with the 3.68 {micro}s orbit time of the Advanced Photon Source. The shutter provides high accuracy and efficient use of X-rays at a modest cost.

  20. A fast mechanical shutter for submicrosecond time-resolved synchrotron experiments.

    PubMed

    Gembicky, Milan; Oss, Dan; Fuchs, Ryan; Coppens, Philip

    2005-09-01

    A new high-speed high-repetition-rate X-ray beam shutter for time-resolved photocrystallography at synchrotron sources has been developed and tested. The new design is based on a commercially existing DC servomotor and a frequency-lock control capable linear amplifier. Accurate speed control combined with an air bearing results in extremely low jitter in the motor rotation. Measured jitter at rotation speeds of 12000 to 30000 r min-1 is less than 2 ns at a 6sigma confidence level. The chopper disc is interchangeable, allowing maximum flexibility. The chopper disc currently installed has 45 radial slots which allows synchronization from the 12th to the 20th subfrequencies of the orbit frequency of the Advanced Photon Source storage ring, corresponding to X-ray pulse frequencies of 13.6 to 22.6 kHz. At 30000 r min-1 the opening time window with a 350 microm slot size is 2.11 micros, and correspondingly less with smaller openings, which may be compared with the 3.68 micros orbit time of the Advanced Photon Source. The shutter provides high accuracy and efficient use of X-rays at a modest cost. PMID:16120992

  1. Ultra fast miniaturized real-time PCR: 40 cycles in less than six minutes.

    PubMed

    Neuzil, Pavel; Zhang, Chunyan; Pipper, Juergen; Oh, Sharon; Zhuo, Lang

    2006-01-01

    We have designed, fabricated and tested a real-time PCR chip capable of conducting one thermal cycle in 8.5 s. This corresponds to 40 cycles of PCR in 5 min and 40 s. The PCR system was made of silicon micromachined into the shape of a cantilever terminated with a disc. The thin film heater and a temperature sensor were placed on the disc perimeter. Due to the system's thermal constant of 0.27 s, we have achieved a heating rate of 175 degrees C s(-1) and a cooling rate of -125 degrees C s(-1). A PCR sample encapsulated with mineral oil was dispensed onto a glass cover slip placed on the silicon disc. The PCR cycle time was then determined by heat transfer through the glass, which took only 0.5 s. A real-time PCR sample with a volume of 100 nl was tested using a FAM probe. As the single PCR device occupied an area of only a few square millimeters, devices could be combined into a parallel system to increase throughput. PMID:16807313

  2. A fast 1-D detector for imaging and time resolved SAXS experiments

    NASA Astrophysics Data System (ADS)

    Menk, R. H.; Arfelli, F.; Bernstorff, S.; Pontoni, D.; Sarvestani, A.; Besch, H. J.; Walenta, A. H.

    1999-02-01

    A one-dimensional test detector on the principle of a highly segmented ionization chamber with shielding grid (Frisch grid) was developed to evaluate if this kind of detector is suitable for advanced small-angle X-ray scattering (SAXS) experiments. At present it consists of 128 pixels which can be read out within 0.2 ms with a noise floor of 2000 e-ENC. A quantum efficiency of 80% for a photon energy of 8 keV was achieved. This leads to DQE values of 80% for photon fluxes above 1000 photons/pixel and integration time. The shielding grid is based on the principles of the recently invented MCAT structure and the GEM structure which also allows electron amplification in the gas. In the case of the MCAT structure, an energy resolution of 20% at 5.9 keV was observed. The gas amplification mode enables imaging with this integrating detector on a subphoton noise level with respect to the integration time. Preliminary experiments of saturation behavior show that this kind of detector digests a photon flux density up to 10 12 photons/mm 2 s and operates linearly. A spatial resolution of at least three line pairs/mm was obtained. All these features show that this type of detector is well suited for time-resolved SAXS experiments as well as high flux imaging applications.

  3. Influence of the gas and particle residence time on fast pyrolysis of lignite

    SciTech Connect

    Cui, L.J.; Song, W.L.; Zhang, J.Y.; Yao, J.Z.; Lin, W.G.

    2007-06-15

    Coal resource is abundant in China, while the reserves of natural gas and petroleum are limited. Due to the rapid increase in the number of automobiles, a competitive way to produce liquid fuels from coal is urgently needed in China. A so-called 'coal topping process' is under development at the Institute of Process Engineering, Chinese Academy of Sciences, from which liquid products can be obtained by flash pyrolysis in an integrated circulating fluidized bed system. In order to achieve a high yield of liquid products from high volatile coal, controlling the residence time of coal particles and produced gas may be of importance for minimizing the degree of the secondary reactions; i.e., polymerization and cracking of the liquid products. Experiments of the flash pyrolysis of coal have been conducted in an entrained bed reactor which is especially designed to study the influence of the coal particle residence time on the product distribution. The results show that the gaseous, liquid, and solid product distribution, the gas compositions as well as the liquid compositions depend strongly on the gas and particle residence time.

  4. Fast-timing study of the l -forbidden 1 /2+→3 /2+ M 1 transition in 129Sn

    NASA Astrophysics Data System (ADS)

    Licǎ, R.; Mach, H.; Fraile, L. M.; Gargano, A.; Borge, M. J. G.; Mǎrginean, N.; Sotty, C. O.; Vedia, V.; Andreyev, A. N.; Benzoni, G.; Bomans, P.; Borcea, R.; Coraggio, L.; Costache, C.; De Witte, H.; Flavigny, F.; Fynbo, H.; Gaffney, L. P.; Greenlees, P. T.; Harkness-Brennan, L. J.; Huyse, M.; Ibáñez, P.; Judson, D. S.; Konki, J.; Korgul, A.; Kröll, T.; Kurcewicz, J.; Lalkovski, S.; Lazarus, I.; Lund, M. V.; Madurga, M.; Mǎrginean, R.; Marroquín, I.; Mihai, C.; Mihai, R. E.; Morales, A. I.; Nácher, E.; Negret, A.; Page, R. D.; Pakarinen, J.; Pascu, S.; Paziy, V.; Perea, A.; Pérez-Liva, M.; Picado, E.; Pucknell, V.; Rapisarda, E.; Rahkila, P.; Rotaru, F.; Swartz, J. A.; Tengblad, O.; Van Duppen, P.; Vidal, M.; Wadsworth, R.; Walters, W. B.; Warr, N.; IDS Collaboration

    2016-04-01

    The levels in 129Sn populated from the β- decay of 129In isomers were investigated at the ISOLDE facility of CERN using the newly commissioned ISOLDE Decay Station (IDS). The lowest 1 /2+ state and the 3 /2+ ground state in 129Sn are expected to have configurations dominated by the neutron s1 /2 (l =0 ) and d3 /2 (l =2 ) single-particle states, respectively. Consequently, these states should be connected by a somewhat slow l -forbidden M 1 transition. Using fast-timing spectroscopy we have measured the half-life of the 1 /2+ 315.3-keV state, T1 /2= 19(10) ps, which corresponds to a moderately fast M 1 transition. Shell-model calculations using the CD-Bonn effective interaction, with standard effective charges and g factors, predict a 4-ns half-life for this level. We can reconcile the shell-model calculations to the measured T1 /2 value by the renormalization of the M 1 effective operator for neutron holes.

  5. Radiometric Calibration of Mars HiRISE High Resolution Imagery Based on Fpga

    NASA Astrophysics Data System (ADS)

    Hou, Yifan; Geng, Xun; Xing, Shuai; Tang, Yonghe; Xu, Qing

    2016-06-01

    Due to the large data amount of HiRISE imagery, traditional radiometric calibration method is not able to meet the fast processing requirements. To solve this problem, a radiometric calibration system of HiRISE imagery based on field program gate array (FPGA) is designed. The montage gap between two channels caused by gray inconsistency is removed through histogram matching. The calibration system is composed of FPGA and DSP, which makes full use of the parallel processing ability of FPGA and fast computation as well as flexible control characteristic of DSP. Experimental results show that the designed system consumes less hardware resources and the real-time processing ability of radiometric calibration of HiRISE imagery is improved.

  6. Fast analysis of wide-band scattering from electrically large targets with time-domain parabolic equation method

    NASA Astrophysics Data System (ADS)

    He, Zi; Chen, Ru-Shan

    2016-03-01

    An efficient three-dimensional time domain parabolic equation (TDPE) method is proposed to fast analyze the narrow-angle wideband EM scattering properties of electrically large targets. The finite difference (FD) of Crank-Nicolson (CN) scheme is used as the traditional tool to solve the time-domain parabolic equation. However, a huge computational resource is required when the meshes become dense. Therefore, the alternating direction implicit (ADI) scheme is introduced to discretize the time-domain parabolic equation. In this way, the reduced transient scattered fields can be calculated line by line in each transverse plane for any time step with unconditional stability. As a result, less computational resources are required for the proposed ADI-based TDPE method when compared with both the traditional CN-based TDPE method and the finite-different time-domain (FDTD) method. By employing the rotating TDPE method, the complete bistatic RCS can be obtained with encouraging accuracy for any observed angle. Numerical examples are given to demonstrate the accuracy and efficiency of the proposed method.

  7. Wide-field time-gated photoluminescence microscopy for fast ultrahigh-sensitivity imaging of photoluminescent probes.

    PubMed

    Razali, Wan A W; Sreenivasan, Varun K A; Bradac, Carlo; Connor, Mark; Goldys, Ewa M; Zvyagin, Andrei V

    2016-08-01

    Fluorescence microscopy is a fundamental technique for the life sciences, where biocompatible and photostable photoluminescence probes in combination with fast and sensitive imaging systems are continually transforming this field. A wide-field time-gated photoluminescence microscopy system customised for ultrasensitive imaging of unique nanoruby probes with long photoluminescence lifetime is described. The detection sensitivity derived from the long photoluminescence lifetime of the nanoruby makes it possible to discriminate signals from unwanted autofluorescence background and laser backscatter by employing a time-gated image acquisition mode. This mode enabled several-fold improvement of the photoluminescence imaging contrast of discrete nanorubies dispersed on a coverslip. It enabled recovery of the photoluminescence signal emanating from discrete nanorubies when covered by a layer of an organic fluorescent dye, which were otherwise invisible without the use of spectral filtering approaches. Time-gated imaging also facilitated high sensitivity detection of nanorubies in a biological environment of cultured cells. Finally, we monitor the binding kinetics of nanorubies to a functionalised substrate, which exemplified a real-time assay in biological fluids. 3D-pseudo colour images of nanorubies immersed in a highly fluorescent dye solution. Nanoruby photoluminescence is subdued by that of the dye in continuous excitation/imaging (left), however it can be recovered by time-gated imaging (right). At the bottom is schematic diagram of nanoruby assay in a biological fluid. PMID:27264934

  8. On the area of accretion curtains from fast aperiodic time variability of the intermediate polar EX Hya

    NASA Astrophysics Data System (ADS)

    Semena, Andrey N.; Revnivtsev, Mikhail G.; Buckley, David A. H.; Kotze, Marissa M.; Khabibullin, Ildar I.; Breytenbach, Hannes; Gulbis, Amanda A. S.; Coppejans, Rocco; Potter, Stephen B.

    2014-08-01

    We present results of a study of the fast timing variability of the magnetic cataclysmic variable (mCV) EX Hya. It was previously shown that one may expect the rapid flux variability of mCVs to be smeared out at time-scales shorter than the cooling time of hot plasma in the post-shock region of the accretion curtain near the white dwarf (WD) surface. Estimates of the cooling time and the mass accretion rate, thus provide us with a tool to measure the density of the post-shock plasma and the cross-sectional area of the accretion funnel at the WD surface. We have probed the high frequencies in the aperiodic noise of one of the brightest mCV EX Hya with the help of optical telescopes, namely Southern African Large Telescope and the South African Astronomical Observatory 1.9 m telescope. We place upper limits on the plasma cooling time-scale τ < 0.3 s, on the fractional area of the accretion curtain footprint f < 1.6 × 10-4, and a lower limit on the specific mass accretion rate Ṁ/A>3 g s-1 cm-2. We show that measurements of accretion column footprints via eclipse mapping highly overestimate their areas. We deduce a value of Δr/r ≲ 10- 3 as an upper limit to the penetration depth of the accretion disc plasma at the boundary of the magnetosphere.

  9. The effect of age and microstructural white matter integrity on lap time variation and fast-paced walking speed.

    PubMed

    Tian, Qu; Ferrucci, Luigi; Resnick, Susan M; Simonsick, Eleanor M; Shardell, Michelle D; Landman, Bennett A; Venkatraman, Vijay K; Gonzalez, Christopher E; Studenski, Stephanie A

    2016-09-01

    Macrostructural white matter damage (WMD) is associated with less uniform and slower walking in older adults. The effect of age and subclinical microstructural WM degeneration (a potentially earlier phase of WM ischemic damage) on walking patterns and speed is less clear. This study examines the effect of age on the associations of regional microstructural WM integrity with walking variability and speed, independent of macrostructural WMD. This study involved 493 participants (n = 51 young; n = 209 young-old; n = 233 old-old) from the Baltimore Longitudinal Study of Aging. All completed a 400-meter walk test and underwent a concurrent brain MRI with diffusion tensor imaging. Microstructural WM integrity was measured as fractional anisotropy (FA). Walking variability was measured as trend-adjusted variation in time over ten 40-meter laps (lap time variation, LTV). Fast-paced walking speed was assessed as mean lap time (MLT). Multiple linear regression models of FA predicting LTV and MLT were adjusted for age, sex, height, weight, and WM hyperintensities. Independent of WM hyperintensities, lower FA in the body of the corpus callosum was associated with higher LTV and longer MLT only in the young-old. Lower FA in superior longitudinal, inferior fronto-occipital, and uncinate fasciculi, the anterior limb of the internal capsule, and the anterior corona radiate was associated with longer MLT only in the young-old. While macrostructural WMD is known to predict more variable and slower walking in older adults, microstructural WM disruption is independently associated with more variable and slower fast-paced walking only in the young-old. Disrupted regional WM integrity may be a subclinical contributor to abnormal walking at an earlier phase of aging. PMID:26399234

  10. Fast and robust optical flow for time-lapse microscopy using super-voxels

    PubMed Central

    Amat, Fernando; Myers, Eugene W.; Keller, Philipp J.

    2013-01-01

    Motivation: Optical flow is a key method used for quantitative motion estimation of biological structures in light microscopy. It has also been used as a key module in segmentation and tracking systems and is considered a mature technology in the field of computer vision. However, most of the research focused on 2D natural images, which are small in size and rich in edges and texture information. In contrast, 3D time-lapse recordings of biological specimens comprise up to several terabytes of image data and often exhibit complex object dynamics as well as blurring due to the point-spread-function of the microscope. Thus, new approaches to optical flow are required to improve performance for such data. Results: We solve optical flow in large 3D time-lapse microscopy datasets by defining a Markov random field (MRF) over super-voxels in the foreground and applying motion smoothness constraints between super-voxels instead of voxel-wise. This model is tailored to the specific characteristics of light microscopy datasets: super-voxels help registration in textureless areas, the MRF over super-voxels efficiently propagates motion information between neighboring cells and the background subtraction and super-voxels reduce the dimensionality of the problem by an order of magnitude. We validate our approach on large 3D time-lapse datasets of Drosophila and zebrafish development by analyzing cell motion patterns. We show that our approach is, on average, 10 × faster than commonly used optical flow implementations in the Insight Tool-Kit (ITK) and reduces the average flow end point error by 50% in regions with complex dynamic processes, such as cell divisions. Availability: Source code freely available in the Software section at http://janelia.org/lab/keller-lab. Contact: amatf@janelia.hhmi.org or kellerp@janelia.hhmi.org Supplementary information: Supplementary data are available at Bioinformatics online. PMID:23242263

  11. Systematic investigation of effects of exciton–acoustic-phonon scattering on photoluminescence rise times of free excitons in GaAs/Al{sub 0.3}Ga{sub 0.7}As single quantum wells

    SciTech Connect

    Nakayama, Masaaki Ohno, Tatsuya; Furukawa, Yoshiaki

    2015-04-07

    We have systematically investigated the photoluminescence (PL) dynamics of free excitons in GaAs/Al{sub 0.3}Ga{sub 0.7}As single quantum wells, focusing on the energy relaxation process due to exciton–acoustic-phonon scattering under non-resonant and weak excitation conditions as a function of GaAs-layer thickness from 3.6 to 12.0 nm and temperature from 30 to 50 K. The free exciton characteristics were confirmed by observation that the PL decay time has a linear dependence with temperature. We found that the free exciton PL rise rate, which is the reciprocal of the rise time, is inversely linear with the GaAs-layer thickness and linear with temperature. This is consistent with a reported theoretical study of the exciton–acoustic-phonon scattering rate in the energy relaxation process in quantum wells. Consequently, it is conclusively verified that the PL rise rate is dominated by the exciton–acoustic-phonon scattering rate. In addition, from quantitative analysis of the GaAs-layer thickness and temperature dependences, we suggest that the PL rise rate reflects the number of exciton–acoustic-phonon scattering events.

  12. An instrument for time resolved monitoring of fast chemical transitions: Application to the kinetics of refolding of a globular protein

    NASA Astrophysics Data System (ADS)

    Ratner, Vladimir; Haas, Elisha

    1998-05-01

    The dynamics of kinetic intermediates of protein folding can be studied by time resolved measurements of nonradiative excitation energy transfer, in site-specific labeled protein derivatives, combined with fast mixing experiments. A new device based on the single pulse approach was developed. This experiment is performed over two time scales: the "chemical time scale" of the conformational changes (milliseconds), defined by the rates of changes of conformations in the sample, and the "spectroscopic time scale" (nanoseconds) defined by the lifetimes of the excited states of the fluorescent probes. The chemical process was synchronized by means of a fast mixing stopped flow device. The low cost laser used here is suitable for use with dyes with excitation wavelengths of 337 nm and higher. Up to 20 fluorescence decay curves per second, can be measured within a single stopped flow run. Each fluorescence decay curve is recorded within 250 ns or more. The time resolution (of the spectroscopic time scale) was 0.5 ns. The noise level is low enough to estimate distance distributions from energy transfer experiments, provided that the shortest changeable lifetime component of the fluorescence decay of the donor probes would not be lower than ˜4 ns. The amount of double labeled protein which should be used for each experiment in order to obtain a full data set, with time resolution of 10 ms during protein transition, is only fourfold more than the amount needed for a stopped flow study with steady state fluorescence monitoring. The results obtained for refolding of α-lactalbumin in the presence of 1,8-anilino-naphthalene sulfonic acid from the GuHCl induced denatured state, support the model in which the probe has two states. The first state, is characterized by a fluorescence lifetime of 14.2±0.5 ns and the second by a fluorescence lifetime of 0.5±0.4 ns or less. During refolding the dye is transferred from the first state to the second, at a rate that coincides with the

  13. Fast and sensitive detection of mycotoxins in wheat using microfluidics based Real-time Electrochemical Profiling.

    PubMed

    Olcer, Zehra; Esen, Elif; Muhammad, Turghun; Ersoy, Aylin; Budak, Sinan; Uludag, Yıldız

    2014-12-15

    The objective of the study has been the development of a new sensing platform, called Real-time Electrochemical Profiling (REP) that relies on real-time electrochemical immunoassay detection. The proposed REP platform consists of new electrode arrays that are easy to fabricate, has a small imprint allowing microfluidic system integration, enables multiplexed amperometric measurements and performs well in terms of electrochemical immunoassay detection as shown through the deoxynivalenol detection assays. The deoxynivalenol detection has been conducted according to an optimised REP assay protocol using deoxynivalenol standards at varying concentrations and a standard curve was obtained (y=-20.33ln(x)+124.06; R(2)=0.97) with a limit of detection of 6.25 ng/ml. As both ELISA and REP detection methods use horse radish peroxidase as the label and 3.3',5.5'-Tetramethylbenzidine as the substrate, the performance of the REP platform as an ELISA reader has also been investigated and a perfect correlation between the deoxynivalenol concentration and the current response was obtained (y=-14.56ln(x)+101.02; R(2)=0.99). The calibration curves of both assays have been compared to conventional ELISA tests for confirmation. After assay optimisation using toxin spiked buffer, the deoxynivalenol detection assay has also been performed to detect toxins in wheat grain. PMID:24998314

  14. Fast but not intuitive, slow but not reflective: Decision conflict drives reaction times in social dilemmas.

    PubMed

    Evans, Anthony M; Dillon, Kyle D; Rand, David G

    2015-10-01

    When people have the chance to help others at a cost to themselves, are cooperative decisions driven by intuition or reflection? To answer this question, recent studies have tested the relationship between reaction times (RTs) and cooperation, reporting both positive and negative correlations. To reconcile this apparent contradiction, we argue that decision conflict (rather than the use of intuition vs. reflection) drives response times, leading to an inverted-U shaped relationship between RT and cooperation. Studies 1 through 3 show that intermediate decisions take longer than both extremely selfish and extremely cooperative decisions. Studies 4 and 5 find that the conflict between self-interested and cooperative motives explains individual differences in RTs. Manipulating conflictedness causes longer RTs and more intermediate decisions, and RTs mediate the relationship between conflict and intermediate decisions. Finally, Studies 6 and 7 demonstrate that conflict is distinct from reflection by manipulating the use of intuition (vs. reflection). Experimentally promoting reliance on intuition increases cooperation, but has no effects on decision extremity or feelings of conflictedness. In sum, we provide evidence that RTs should not be interpreted as a direct proxy for the use of intuitive or reflective processes, and dissociate the effects of conflict and reflection in social decision making. PMID:26413891

  15. Insertable system for fast turnaround time microwave experiments in a dilution refrigerator.

    PubMed

    Ong, Florian R; Orgiazzi, Jean-Luc; de Waard, Arlette; Frossati, Giorgio; Lupascu, Adrian

    2012-09-01

    Microwave experiments in dilution refrigerators are a central tool in the field of superconducting quantum circuits and other research areas. This type of experiments relied so far on attaching a device to the mixing chamber of a dilution refrigerator. The minimum turnaround time in this case is a few days as required by cooling down and warming up the entire refrigerator. We developed a new approach, in which a suitable sample holder is attached to a cold-insertable probe and brought in contact with transmission lines permanently mounted inside the cryostat. The total turnaround time is 8 h if the target temperature is 80 mK. The lowest attainable temperature is 30 mK. Our system can accommodate up to six transmission lines, with a measurement bandwidth tested from zero frequency to 12 GHz. This bandwidth is limited by low-pass components in the setup; we expect the intrinsic bandwidth to be at least 18 GHz. We present our setup, discuss the experimental procedure, and give examples of experiments enabled by this system. This new measurement method will have a major impact on systematic ultra-low temperature studies using microwave signals, including those requiring quantum coherence. PMID:23020391

  16. Ranque-Hilsch vortex tube thermocycler for fast DNA amplification and real-time optical detection

    NASA Astrophysics Data System (ADS)

    Ebmeier, Ryan J.; Whitney, Scott E.; Sarkar, Amitabha; Nelson, Michael; Padhye, Nisha V.; Gogos, George; Viljoen, Hendrik J.

    2004-12-01

    An innovative polymerase chain reaction (PCR) thermocycler capable of performing real-time optical detection is described below. This device utilizes the Ranque-Hilsch vortex tube in a system to efficiently and rapidly cycle three 20 μL samples between the denaturation, annealing, and elongation temperatures. The reaction progress is displayed real-time by measuring the size of a fluorescent signal emitted by SYBR green/double-stranded DNA complexes. This device can produce significant reaction yields with very small amounts of initial DNA, for example, it can amplify 0.25 fg (˜5 copies) of a 96 bp bacteriophage λ-DNA fragment 2.7×1011-fold by performing 45 cycles in less than 12 min. The optical threshold (150% of the baseline intensity) was passed 8 min into the reaction at cycle 34. Besides direct applications, the speed and sensitivity of this device enables it to be used as a scientific instrument for basic studies such as PCR assembly and polymerase kinetics.

  17. Acronical Risings and Settings

    NASA Astrophysics Data System (ADS)

    Hockey, Thomas A.

    2012-01-01

    A concept found in historical primary sources, and useful in contemporary historiography, is the acronical rising and setting of stars (or planets). Topocentric terms, they provide information about a star's relationship to the Sun and thus its visibility in the sky. Yet there remains ambiguity as to what these two phrases actually mean. "Acronical” is said to have come from the Greek akros ("point,” "summit,” or "extremity") and nux ("night"). While all sources agree that the word is originally Greek, there are alternate etymologies for it. A more serious difficulty with acronical rising and setting is that there are two competing definitions. One I call the Poetical Definition. Acronical rising (or setting) is one of the three Poetical Risings (or Settings) known to classicists. (The other two are cosmical rising/setting, discussed below, and the more familiar helical rising/setting.) The term "poetical" refers to these words use in classical poetry, e. g., that of Columella, Hesiod, Ovid, Pliny the Younger, and Virgil. The Poetical Definition of "acronical” usually is meant in this context. The Poetical Definition of "acronical” is as follows: When a star rises as the Sun sets, it rises acronically. When a star sets as the Sun sets, it sets acronically. In contrast with the Poetical Definition, there also is what I call the Astronomical Definition. The Astronomical Definition is somewhat more likely to appear in astronomical, mathematical, or navigational works. When the Astronomical Definition is recorded in dictionaries, it is often with the protasis "In astronomy, . . . ." The Astronomical Definition of "acronical” is as follows: When a star rises as the Sun sets, it rises acronically. When a star sets as the Sun rises, it sets acronically. I will attempt to sort this all out in my talk.

  18. Chiral-induced self-assembly sphere phase liquid crystal with fast switching time

    SciTech Connect

    Zhu, Ji-Liang; Ni, Shui-Bin; Ping Chen, Chao; Lu, Jian-Gang Su, Yikai; Wu, Dong-Qing; Song, Xiao-Long; Chen, Chao-Yuan; Shieh, Han-Ping D.

    2014-03-03

    A fluid self-assembly sphere phase (SP) of liquid crystal induced by chiral dopant is observed in a narrow temperature range between isotropic and blue phase or between isotropic and chiral nematic phase. The SP consists of three-dimensional twist spheres (3-DTSs) and disclinations among 3-DTSs. The temperature range of the SP has been broadened to more than 85 °C by stabilizing the disclinations with amorphous polymer chains. The electro-optical switching time of the polymer-stabilized SP is demonstrated in sub-millisecond with a low switching electric field of 4.4 V μm{sup −1}, which is of promising applications in displays, 3-D tunable photonic crystals, and phase modulators.

  19. An implicit fast Fourier transform method for integration of the time dependent Schrodinger equation

    SciTech Connect

    Riley, M.E.; Ritchie, A.B.

    1997-12-31

    One finds that the conventional exponentiated split operator procedure is subject to difficulties when solving the time-dependent Schrodinger equation for Coulombic systems. By rearranging the kinetic and potential energy terms in the temporal propagator of the finite difference equations, one can find a propagation algorithm for three dimensions that looks much like the Crank-Nicholson and alternating direction implicit methods for one- and two-space-dimensional partial differential equations. The authors report investigations of this novel implicit split operator procedure. The results look promising for a purely numerical approach to certain electron quantum mechanical problems. A charge exchange calculation is presented as an example of the power of the method.

  20. Rapid quantification of microRNAs in plasma using a fast real-time PCR system.

    PubMed

    Andrews, William John; Brown, Eoin Daniel; Dellett, Margaret; Hogg, Ruth Esther; Simpson, David Arthur

    2015-05-01

    The ability to rapidly detect circulating small RNAs, in particular microRNAs (miRNAs), would further increase their already established potential as biomarkers for a range of conditions. One rate-limiting factor in miRNA detection is the time taken to perform quantitative real-time PCR (qPCR) amplification. We therefore evaluated the ability of a novel thermal cycler to perform this step in less than 10 minutes. Quantitative PCR was performed on an xxpress thermal cycler (BJS Biotechnologies), which employs a resistive heating system and forced air cooling to achieve thermal ramp rates of 10°C/s, and a conventional Peltier-controlled LightCycler 480 system (Roche) ramping at 4.8°C/s. The quantification cycle (Cq) for detection of 18S rDNA from a standard genomic DNA sample was significantly more variable across the block (F-test, P = 2.4 × 10(-25)) for the xxpress (20.01 ± 0.47 sd) than for the LightCycler (19.87 ± 0.04 sd). RNA was extracted from human plasma, reverse transcribed, and a panel of miRNAs was amplified and detected using SYBR Green. The sensitivities of the two systems were broadly comparable-both detected a panel of miRNAs reliably, and both indicated similar relative abundances. The xxpress thermal cycler facilitates rapid qPCR detection of small RNAs and brings point-of-care diagnostics based upon detection of circulating miRNAs a step closer to reality. PMID:25967903

  1. Fast time-of-flight camera based surface registration for radiotherapy patient positioning

    SciTech Connect

    Placht, Simon; Stancanello, Joseph; Schaller, Christian; Balda, Michael; Angelopoulou, Elli

    2012-01-15

    Purpose: This work introduces a rigid registration framework for patient positioning in radiotherapy, based on real-time surface acquisition by a time-of-flight (ToF) camera. Dynamic properties of the system are also investigated for future gating/tracking strategies. Methods: A novel preregistration algorithm, based on translation and rotation-invariant features representing surface structures, was developed. Using these features, corresponding three-dimensional points were computed in order to determine initial registration parameters. These parameters became a robust input to an accelerated version of the iterative closest point (ICP) algorithm for the fine-tuning of the registration result. Distance calibration and Kalman filtering were used to compensate for ToF-camera dependent noise. Additionally, the advantage of using the feature based preregistration over an ''ICP only'' strategy was evaluated, as well as the robustness of the rigid-transformation-based method to deformation. Results: The proposed surface registration method was validated using phantom data. A mean target registration error (TRE) for translations and rotations of 1.62 {+-} 1.08 mm and 0.07 deg. {+-} 0.05 deg., respectively, was achieved. There was a temporal delay of about 65 ms in the registration output, which can be seen as negligible considering the dynamics of biological systems. Feature based preregistration allowed for accurate and robust registrations even at very large initial displacements. Deformations affected the accuracy of the results, necessitating particular care in cases of deformed surfaces. Conclusions: The proposed solution is able to solve surface registration problems with an accuracy suitable for radiotherapy cases where external surfaces offer primary or complementary information to patient positioning. The system shows promising dynamic properties for its use in gating/tracking applications. The overall system is competitive with commonly-used surface

  2. Real-time tracking and fast retrieval of persons in multiple surveillance cameras of a shopping mall

    NASA Astrophysics Data System (ADS)

    Bouma, Henri; Baan, Jan; Landsmeer, Sander; Kruszynski, Chris; van Antwerpen, Gert; Dijk, Judith

    2013-05-01

    The capability to track individuals in CCTV cameras is important for e.g. surveillance applications at large areas such as train stations, airports and shopping centers. However, it is laborious to track and trace people over multiple cameras. In this paper, we present a system for real-time tracking and fast interactive retrieval of persons in video streams from multiple static surveillance cameras. This system is demonstrated in a shopping mall, where the cameras are positioned without overlapping fields-of-view and have different lighting conditions. The results show that the system allows an operator to find the origin or destination of a person more efficiently. The misses are reduced with 37%, which is a significant improvement.

  3. Real-time dedispersion for fast radio transient surveys, using auto tuning on many-core accelerators

    NASA Astrophysics Data System (ADS)

    Sclocco, A.; van Leeuwen, J.; Bal, H. E.; van Nieuwpoort, R. V.

    2016-01-01

    Dedispersion, the removal of deleterious smearing of impulsive signals by the interstellar matter, is one of the most intensive processing steps in any radio survey for pulsars and fast transients. We here present a study of the parallelization of this algorithm on many-core accelerators, including GPUs from AMD and NVIDIA, and the Intel Xeon Phi. We find that dedispersion is inherently memory-bound. Even in a perfect scenario, hardware limitations keep the arithmetic intensity low, thus limiting performance. We next exploit auto-tuning to adapt dedispersion to different accelerators, observations, and even telescopes. We demonstrate that the optimal settings differ between observational setups, and that auto-tuning significantly improves performance. This impacts time-domain surveys from Apertif to SKA.

  4. Half-life of the Iπ = 4- Intruder State in 34P Using LaBr3:Ce Fast Timing

    NASA Astrophysics Data System (ADS)

    Mason, P. J. R.; Alharbi, T.; Regan, P. H.; Mǎrginean, N.; Podolyàk, Zs; Alkhomashi, N.; Bender, P. C.; Bowry, M.; Bostan, M.; Bucurescu, D.; Bruce, A. M.; Cǎta-Danil, G.; Cǎta-Danil, I.; Chakrabarti, R.; Deleanu, D.; Detistov, P.; Erduran, M. N.; Filipescu, D.; Garg, U.; Glodariu, T.; Ghiţǎ, D.; Ghugre, S. S.; Kusoglu, A.; Mǎrginean, R.; Mihai, C.; Nakhostin, M.; Negret, A.; Pascu, S.; Rodríguez Triguero, C.; Sava, T.; Simpson, E. C.; Sinha, A. K.; Stroe, L.; Suliman, G.; Zamfir, N. V.

    2012-09-01

    The half-life of the Iπ = 4- intruder state at 2305 keV in 3415P19 has been measured using γ-ray coincident fast timing with LaBr3:Ce scintillation detectors. Excited states in 34P were populated in the 18O(18O,pn)34P reaction at a beam energy of 36 MeV at the Tandem Laboratory at the National Institute of Physics and Nuclear Engineering, Bucharest, Romania. A half-life of t1/2 ~ 2 ns was obtained for the 4- state, giving an M2 reduced transition probability consistent with similar transitions in this mass region and confirming the intruder-parity nature of the state.

  5. Positive Contrast with Alternating Repetition Time SSFP (PARTS): A Fast Imaging Technique for SPIO-Labeled Cells

    PubMed Central

    Çukur, Tolga; Yamada, Mayumi; Overall, William R.; Yang, Phillip; Nishimura, Dwight G.

    2011-01-01

    There has been recent interest in positive-contrast MRI methods for noninvasive tracking of cells labeled with superparamagnetic iron-oxide (SPIO) nanoparticles. Low-tip-angle balanced steady-state free precession (bSSFP) sequences have been used for fast, high-resolution, and flow-insensitive positive-contrast imaging; however, the contrast can be compromised by the limited suppression of the on-resonant and fat signals. In this work, a new technique that produces positive contrast with alternating repetition time SSFP (PARTS) is proposed to achieve robust background suppression for a broad range of tissue parameters. In vitro and in vivo experiments demonstrate the reliability of the generated positive contrast. The results indicate that PARTS can enhance the suppression level by up to 18 dB compared with conventional bSSFP. PMID:20099331

  6. Fast time-lens-based line-scan single-pixel camera with multi-wavelength source

    PubMed Central

    Guo, Qiang; Chen, Hongwei; Weng, Zhiliang; Chen, Minghua; Yang, Sigang; Xie, Shizhong

    2015-01-01

    A fast time-lens-based line-scan single-pixel camera with multi-wavelength source is proposed and experimentally demonstrated in this paper. A multi-wavelength laser instead of a mode-locked laser is used as the optical source. With a diffraction grating and dispersion compensating fibers, the spatial information of an object is converted into temporal waveforms which are then randomly encoded, temporally compressed and captured by a single-pixel photodetector. Two algorithms (the dictionary learning algorithm and the discrete cosine transform-based algorithm) for image reconstruction are employed, respectively. Results show that the dictionary learning algorithm has greater capability to reduce the number of compressive measurements than the DCT-based algorithm. The effective imaging frame rate increases from 200 kHz to 1 MHz, which shows a significant improvement in imaging speed over conventional single-pixel cameras. PMID:26417527

  7. Hamilton-Jacobi equation for the least-action/least-time dynamical path based on fast marching method

    NASA Astrophysics Data System (ADS)

    Dey, Bijoy K.; Janicki, Marek R.; Ayers, Paul W.

    2004-10-01

    Classical dynamics can be described with Newton's equation of motion or, totally equivalently, using the Hamilton-Jacobi equation. Here, the possibility of using the Hamilton-Jacobi equation to describe chemical reaction dynamics is explored. This requires an efficient computational approach for constructing the physically and chemically relevant solutions to the Hamilton-Jacobi equation; here we solve Hamilton-Jacobi equations on a Cartesian grid using Sethian's fast marching method [J. A. Sethian, Proc. Natl. Acad. Sci. USA 93, 1591 (1996)]. Using this method, we can—starting from an arbitrary initial conformation—find reaction paths that minimize the action or the time. The method is demonstrated by computing the mechanism for two different systems: a model system with four different stationary configurations and the H+H2→H2+H reaction. Least-time paths (termed brachistochrones in classical mechanics) seem to be a suitable chioce for the reaction coordinate, allowing one to determine the key intermediates and final product of a chemical reaction. For conservative systems the Hamilton-Jacobi equation does not depend on the time, so this approach may be useful for simulating systems where important motions occur on a variety of different time scales.

  8. Fast history matching of time-lapse seismic and production data for high resolution models

    NASA Astrophysics Data System (ADS)

    Jimenez Arismendi, Eduardo Antonio

    Integrated reservoir modeling has become an important part of day-to-day decision analysis in oil and gas management practices. A very attractive and promising technology is the use of time-lapse or 4D seismic as an essential component in subsurface modeling. Today, 4D seismic is enabling oil companies to optimize production and increase recovery through monitoring fluid movements throughout the reservoir. 4D seismic advances are also being driven by an increased need by the petroleum engineering community to become more quantitative and accurate in our ability to monitor reservoir processes. Qualitative interpretations of time-lapse anomalies are being replaced by quantitative inversions of 4D seismic data to produce accurate maps of fluid saturations, pore pressure, temperature, among others. Within all steps involved in this subsurface modeling process, the most demanding one is integrating the geologic model with dynamic field data, including 4Dseismic when available. The validation of the geologic model with observed dynamic data is accomplished through a "history matching" (HM) process typically carried out with well-based measurements. Due to low resolution of production data, the validation process is severely limited in its reservoir areal coverage, compromising the quality of the model and any subsequent predictive exercise. This research will aim to provide a novel history matching approach that can use information from high-resolution seismic data to supplement the areally sparse production data. The proposed approach will utilize streamline-derived sensitivities as means of relating the forward model performance with the prior geologic model. The essential ideas underlying this approach are similar to those used for high-frequency approximations in seismic wave propagation. In both cases, this leads to solutions that are defined along "streamlines" (fluid flow), or "rays" (seismic wave propagation). Synthetic and field data examples will be used

  9. Rethinking fast and slow based on a critique of reaction-time reverse inference

    PubMed Central

    Krajbich, Ian; Bartling, Björn; Hare, Todd; Fehr, Ernst

    2015-01-01

    Do people intuitively favour certain actions over others? In some dual-process research, reaction-time (RT) data have been used to infer that certain choices are intuitive. However, the use of behavioural or biological measures to infer mental function, popularly known as ‘reverse inference', is problematic because it does not take into account other sources of variability in the data, such as discriminability of the choice options. Here we use two example data sets obtained from value-based choice experiments to demonstrate that, after controlling for discriminability (that is, strength-of-preference), there is no evidence that one type of choice is systematically faster than the other. Moreover, using specific variations of a prominent value-based choice experiment, we are able to predictably replicate, eliminate or reverse previously reported correlations between RT and selfishness. Thus, our findings shed crucial light on the use of RT in inferring mental processes and strongly caution against using RT differences as evidence favouring dual-process accounts. PMID:26135809

  10. Analysis of UAS DAA Alerting in Fast-Time Simulations without DAA Mitigation

    NASA Technical Reports Server (NTRS)

    Thipphavong, David P.; Santiago, Confesor; Isaacson, Douglas R.; Lee, Seung Man; Park, Chunki; Refai, Mohamad Said; Snow, James

    2015-01-01

    Realization of the expected proliferation of Unmanned Aircraft System (UAS) operations in the National Airspace System (NAS) depends on the development and validation of performance standards for UAS Detect and Avoid (DAA) Systems. The RTCA Special Committee 228 is charged with leading the development of draft Minimum Operational Performance Standards (MOPS) for UAS DAA Systems. NASA, as a participating member of RTCA SC-228 is committed to supporting the development and validation of draft requirements for DAA alerting system performance. A recent study conducted using NASA's ACES (Airspace Concept Evaluation System) simulation capability begins to address questions surrounding the development of draft MOPS for DAA alerting systems. ACES simulations were conducted to study the performance of alerting systems proposed by the SC-228 DAA Alerting sub-group. Analysis included but was not limited to: 1) correct alert (and timeliness), 2) false alert (and severity and duration), 3) missed alert, and 4) probability of an alert type at the time of loss of well clear. The performance of DAA alerting systems when using intent vs. dead-reckoning for UAS ownship trajectories was also compared. The results will be used by SC-228 to inform decisions about the surveillance standards of UAS DAA systems and future requirements development and validation efforts.

  11. Fast determination of beef quality parameters with time-domain nuclear magnetic resonance spectroscopy and chemometrics.

    PubMed

    Pereira, Fabíola Manhas Verbi; Bertelli Pflanzer, Sérgio; Gomig, Thaísa; Lugnani Gomes, Carolina; de Felício, Pedro Eduardo; Colnago, Luiz Alberto

    2013-04-15

    The noteworthy of this study is to predict seven quality parameters for beef samples using time-domain nuclear magnetic resonance (TD-NMR) relaxometry data and multivariate models. Samples from 61 Bonsmara heifers were separated into five groups based on genetic (breeding composition) and feed system (grain and grass feed). Seven sample parameters were analyzed by reference methods; among them, three sensorial parameters, flavor, juiciness and tenderness and four physicochemical parameters, cooking loss, fat and moisture content and instrumental tenderness using Warner Bratzler shear force (WBSF). The raw beef samples of the same animals were analyzed by TD-NMR relaxometry using Carr-Purcell-Meiboom-Gill (CPMG) and Continuous Wave-Free Precession (CWFP) sequences. Regression models computed by partial least squares (PLS) chemometric technique using CPMG and CWFP data and the results of the classical analysis were constructed. The results allowed for the prediction of aforementioned seven properties. The predictive ability of the method was evaluated using the root mean square error (RMSE) for the calibration (RMSEC) and validation (RMSEP) data sets. The reference and predicted values showed no significant differences at a 95% confidence level. PMID:23601874

  12. Dynamic time warping in phoneme modeling for fast pronunciation error detection.

    PubMed

    Miodonska, Zuzanna; Bugdol, Marcin D; Krecichwost, Michal

    2016-02-01

    The presented paper describes a novel approach to the detection of pronunciation errors. It makes use of the modeling of well-pronounced and mispronounced phonemes by means of the Dynamic Time Warping (DTW) algorithm. Four approaches that make use of the DTW phoneme modeling were developed to detect pronunciation errors: Variations of the Word Structure (VoWS), Normalized Phoneme Distances Thresholding (NPDT), Furthest Segment Search (FSS) and Normalized Furthest Segment Search (NFSS). The performance evaluation of each module was carried out using a speech database of correctly and incorrectly pronounced words in the Polish language, with up to 10 patterns of every trained word from a set of 12 words having different phonetic structures. The performance of DTW modeling was compared to Hidden Markov Models (HMM) that were used for the same four approaches (VoWS, NPDT, FSS, NFSS). The average error rate (AER) was the lowest for DTW with NPDT (AER=0.287) and scored better than HMM with FSS (AER=0.473), which was the best result for HMM. The DTW modeling was faster than HMM for all four approaches. This technique can be used for computer-assisted pronunciation training systems that can work with a relatively small training speech corpus (less than 20 patterns per word) to support speech therapy at home. PMID:26739104

  13. Fast detection of MYCN copy number alterations in brain neuronal tumors by real-time PCR.

    PubMed

    Malakho, S G; Korshunov, A; Stroganova, A M; Poltaraus, A B

    2008-01-01

    Increased MYCN gene copy number is a characteristic property of neurogenic tumors. Fluorescence in situ hybridization (FISH) and array-based comparative genomic hybridization (array-CGH) are traditionally used to determine MYCN amplification for tumor stratification. A unique ability of real-time quantitative polymerase chain reaction (qPCR) to determine gene copy number, even within a small percent of observed tumor cells, and can be more appropriate. MYCN genomic copy number from 44 human brain tumors (22 medulloblastomas and 22 neurocytomas) was determined by means of FISH, array-CGH, and qPCR. By qPCR, with the original set of oligonucleotides, 17 out of 44 (38.6%) tumors were found to contain a 1.3- to 2.9-fold increase of MYCN defined as low-level gain. An absolute qPCR method was used to get high accuracy of results. Strong correlation was observed between the three methods: for medulloblastomas, r=1 (P<0.01) between FISH and array-CGH and r=0.92 (P<0.01) between qPCR and FISH/array-CGH. For neurocytomas, r=0.9 (P<0.01) between FISH and array-CGH and r=0.34/0.43 (P<0.01) between qPCR and FISH/array-CGH. Absolute qPCR assays possess high precision compared to other conventional methods and can be used for accurate and quickness detection of MYCN status (low-level gene gain and amplification). PMID:18348317

  14. Quantum correlations in Newtonian space and time: arbitrarily fast communication or nonlocality

    NASA Astrophysics Data System (ADS)

    Gisin, Nicolas

    2013-03-01

    Experimental violations of Bell inequalities using space-like separated measurements precludes the explanation of quantum correlations through causal influences propagating at subluminal speed. Yet, ``everything looks as if the two parties somehow communicate behind the scene.'' We investigate the assumption that they do so at a speed faster than light, though finite. Such an assumption doesn't respect the spirit of Einstein relativity. However, it is not crystal clear that such ``communication behind the scene'' would contradict relativity. Indeed, one could imagine that this communication remains for ever hidden to humans, i.e. that it could not be controlled by humans, only Nature exploits it to produce correlations that can't be explained by usual common causes. To define faster than light hidden communication requires a universal privileged reference frame in which this faster than light speed is defined. Again, such a universal privileged frame is not in the spirit of relativity, but it is also clearly not in contradiction: for example the reference frame in which the cosmic microwave background radiation is isotropic defines such a privileged frame. Hence, a priori, a hidden communication explanation is not more surprising than nonlocality. We prove that for any finite speed, such models predict correlations that can be exploited for faster-than-light communication. This superluminal communication doesn't require access to any hidden physical quantities, but only the manipulation of measurement devices at the level of our present-day description of quantum experiments. Consequently, all possible explanations of quantum correlations that satisfy the principle of continuity, which states that everything propagates gradually and continuously through space and time, or in other words, all combination of local common causes and direct causes that reproduce quantum correlations, lead to faster than light communication. Accordingly, either there is superluminal

  15. Tharsis Rise Graben

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 22 May 2002) The Science This image is located in the northwestern portion of the Tharsis Rise at about 12 N and 125 W (235 E). What is immediately noticeable in this image is the series of linear features that are called graben. These features are associated with crustal extension which results in a series of up and down blocks of crust that run perpendicular to the direction of the extension. Images of Mars have shown a large number of these tectonic features concentrated on or near the Tharsis region. The Tharsis region is an enormous bulge that causes major tectonic disruptions across the planet when it tries to settle down from its height and reach equilibrium with the rest of the planet. The graben in this image display a number of preferential directions indicating that the crustal stresses that caused the graben have changed over time. By examining the cross-cutting relationships between the features, it is possible to reassemble the history of the area. The Story Now, if you thought that Mars was almost perfectly round, think again! The red planet has a large bulge sticking out from it called Tharsis. Almost 3,000 miles across, this enormous region rises almost four miles above the average radius of the planet. That's quite a bulge! Since Tharsis the land of the largest volcanoes in the solar system, it may have been formed by both the uplift of land from tectonic action and the build-up of lava flows. Tharsis can cause some pretty major tectonic disruptions across the planet when it tries to settle down from its height and reach a better equilibrium with the rest of the planet. In this image, located in the northwestern portion of the Tharsis Rise, a whole lot of lowered features stripe the landscape. They are called grabens, and formed when the crust of the planet was stretched tectonically. This kind of crustal extension (or stretching) tends to form a series of up-and-down blocks of crust that run perpendicular to the direction of the crustal

  16. Probing the Time Scale of FPOP (Fast Photochemical Oxidation of Proteins): Radical Reactions Extend Over Tens of Milliseconds

    NASA Astrophysics Data System (ADS)

    Vahidi, Siavash; Konermann, Lars

    2016-07-01

    Hydroxyl radical (ṡOH) labeling with mass spectrometry detection reports on protein conformations and interactions. Fast photochemical oxidation of proteins (FPOP) involves ṡOH production via H2O2 photolysis by UV laser pulses inside a flow tube. The experiments are conducted in the presence of a scavenger (usually glutamine) that shortens the ṡOH lifetime. The literature claims that FPOP takes place within 1 μs. This ultrafast time scale implies that FPOP should be immune to labeling-induced artifacts that may be encountered with other techniques. Surprisingly, the FPOP time scale has never been validated in direct kinetic measurements. Here we employ flash photolysis for probing oxidation processes under typical FPOP conditions. Bleaching of the reporter dye cyanine-5 (Cy5) served as readout of the time-dependent radical milieu. Surprisingly, Cy5 oxidation extends over tens of milliseconds. This time range is four orders of magnitude longer than expected from the FPOP literature. We demonstrate that the glutamine scavenger generates metastable secondary radicals in the FPOP solution, and that these radicals lengthen the time frame of Cy5 oxidation. Cy5 and similar dyes are widely used for monitoring the radical dose experienced by proteins in solution. The measured Cy5 kinetics thus strongly suggest that protein oxidation in FPOP extends over a much longer time window than previously thought (i.e., many milliseconds instead of one microsecond). The optical approach developed here should be suitable for assessing the performance of future FPOP-like techniques with improved temporal labeling characteristics.

  17. Probing the Time Scale of FPOP (Fast Photochemical Oxidation of Proteins): Radical Reactions Extend Over Tens of Milliseconds.

    PubMed

    Vahidi, Siavash; Konermann, Lars

    2016-07-01

    Hydroxyl radical (⋅OH) labeling with mass spectrometry detection reports on protein conformations and interactions. Fast photochemical oxidation of proteins (FPOP) involves ⋅OH production via H2O2 photolysis by UV laser pulses inside a flow tube. The experiments are conducted in the presence of a scavenger (usually glutamine) that shortens the ⋅OH lifetime. The literature claims that FPOP takes place within 1 μs. This ultrafast time scale implies that FPOP should be immune to labeling-induced artifacts that may be encountered with other techniques. Surprisingly, the FPOP time scale has never been validated in direct kinetic measurements. Here we employ flash photolysis for probing oxidation processes under typical FPOP conditions. Bleaching of the reporter dye cyanine-5 (Cy5) served as readout of the time-dependent radical milieu. Surprisingly, Cy5 oxidation extends over tens of milliseconds. This time range is four orders of magnitude longer than expected from the FPOP literature. We demonstrate that the glutamine scavenger generates metastable secondary radicals in the FPOP solution, and that these radicals lengthen the time frame of Cy5 oxidation. Cy5 and similar dyes are widely used for monitoring the radical dose experienced by proteins in solution. The measured Cy5 kinetics thus strongly suggest that protein oxidation in FPOP extends over a much longer time window than previously thought (i.e., many milliseconds instead of one microsecond). The optical approach developed here should be suitable for assessing the performance of future FPOP-like techniques with improved temporal labeling characteristics. Graphical Abstract ᅟ. PMID:27067899

  18. Probing the Time Scale of FPOP (Fast Photochemical Oxidation of Proteins): Radical Reactions Extend Over Tens of Milliseconds

    NASA Astrophysics Data System (ADS)

    Vahidi, Siavash; Konermann, Lars

    2016-04-01

    Hydroxyl radical (ṡOH) labeling with mass spectrometry detection reports on protein conformations and interactions. Fast photochemical oxidation of proteins (FPOP) involves ṡOH production via H2O2 photolysis by UV laser pulses inside a flow tube. The experiments are conducted in the presence of a scavenger (usually glutamine) that shortens the ṡOH lifetime. The literature claims that FPOP takes place within 1 μs. This ultrafast time scale implies that FPOP should be immune to labeling-induced artifacts that may be encountered with other techniques. Surprisingly, the FPOP time scale has never been validated in direct kinetic measurements. Here we employ flash photolysis for probing oxidation processes under typical FPOP conditions. Bleaching of the reporter dye cyanine-5 (Cy5) served as readout of the time-dependent radical milieu. Surprisingly, Cy5 oxidation extends over tens of milliseconds. This time range is four orders of magnitude longer than expected from the FPOP literature. We demonstrate that the glutamine scavenger generates metastable secondary radicals in the FPOP solution, and that these radicals lengthen the time frame of Cy5 oxidation. Cy5 and similar dyes are widely used for monitoring the radical dose experienced by proteins in solution. The measured Cy5 kinetics thus strongly suggest that protein oxidation in FPOP extends over a much longer time window than previously thought (i.e., many milliseconds instead of one microsecond). The optical approach developed here should be suitable for assessing the performance of future FPOP-like techniques with improved temporal labeling characteristics.

  19. Medical applications of fast 3D cameras in real-time image-guided radiotherapy (IGRT) of cancer

    NASA Astrophysics Data System (ADS)

    Li, Shidong; Li, Tuotuo; Geng, Jason

    2013-03-01

    Dynamic volumetric medical imaging (4DMI) has reduced motion artifacts, increased early diagnosis of small mobile tumors, and improved target definition for treatment planning. High speed cameras for video, X-ray, or other forms of sequential imaging allow a live tracking of external or internal movement useful for real-time image-guided radiation therapy (IGRT). However, none of 4DMI can track real-time organ motion and no camera has correlated with 4DMI to show volumetric changes. With a brief review of various IGRT techniques, we propose a fast 3D camera for live-video stereovision, an automatic surface-motion identifier to classify body or respiratory motion, a mechanical model for synchronizing the external surface movement with the internal target displacement by combination use of the real-time stereovision and pre-treatment 4DMI, and dynamic multi-leaf collimation for adaptive aiming the moving target. Our preliminary results demonstrate that the technique is feasible and efficient in IGRT of mobile targets. A clinical trial has been initiated for validation of its spatial and temporal accuracies and dosimetric impact for intensity-modulated RT (IMRT), volumetric-modulated arc therapy (VMAT), and stereotactic body radiotherapy (SBRT) of any mobile tumors. The technique can be extended for surface-guided stereotactic needle insertion in biopsy of small lung nodules.

  20. Ultra-fast-framing schlieren system for studies of the time evolution of jets in supersonic crossflows

    NASA Astrophysics Data System (ADS)

    Ben-Yakar, A.; Hanson, R. K.

    2002-06-01

    A new ultra-fast camera system is used to study the time evolution of jets in supersonic crossflows via schlieren imaging. The commercial high-speed camera includes eight independent intensified charged couple devices (ICCDs) and is capable of acquiring images at rates up to 100 MHz. A long-duration (up to 200 µs) xenon flashlamp is used as the continuous light source. The exposure times of the ICCDs and the interframing times were designed to achieve schlieren images with high spatial and temporal resolution. Example data are presented for a hydrogen jet injected into a high total enthalpy supersonic crossflow, generated using a short-duration impulse facility (expansion tube). The large-eddy convection characteristics of the jet, its penetration and the unsteady nature of the shock wave around it are analyzed. Temporal correlations, such as the movement of organized (coherent) structures and fluctuations in the bow-shock, are readily perceived by assembling the eight consecutive images as a movie (http://navier.stanford.edu/hanson/propulsion/scramjet/movies/t1179.html).

  1. Antarctic ice rise formation, evolution, and stability

    NASA Astrophysics Data System (ADS)

    Favier, Lionel; Pattyn, Frank

    2015-06-01

    Antarctic ice rises originate from the contact between ice shelves and one of the numerous topographic highs emerging from the edge of the continental shelf. While investigations of the Raymond effect indicate their millennial-scale stability, little is known about their formation and their role in ice shelf stability. Here we present for the first time the simulation of an ice rise using the BISICLES model. The numerical results successfully reproduce several field-observable features, such as the substantial thinning downstream of the ice rise and the successive formation of a promontory and ice rise with stable radial ice flow center, showing that ice rises are formed during the ice sheet deglaciation. We quantify the ice rise buttressing effect, found to be mostly transient, delaying grounding line retreat significantly but resulting in comparable steady state positions. We demonstrate that ice rises are key in controlling simulations of Antarctic deglaciation.

  2. Non-destructive thermal wave method applied to study thermal properties of fast setting time endodontic cement

    NASA Astrophysics Data System (ADS)

    Picolloto, A. M.; Mariucci, V. V. G.; Szpak, W.; Medina, A. N.; Baesso, M. L.; Astrath, N. G. C.; Astrath, F. B. G.; Santos, A. D.; Moraes, J. C. S.; Bento, A. C.

    2013-11-01

    The thermal wave method is applied for thermal properties measurement in fast endodontic cement (CER). This new formula is developed upon using Portland cement in gel and it was successfully tested in mice with good biocompatibility and stimulated mineralization. Recently, thermal expansion and setting time were measured, conferring to this material twice faster hardening than the well known Angelus Mineral trioxide aggregate (MTA) the feature of fast hardening (˜7 min) and with similar thermal expansion (˜12 μstrain/ °C). Therefore, it is important the knowledge of thermal properties like thermal diffusivity, conductivity, effusivity in order to match thermally the tissue environment upon its application in filling cavities of teeth. Photothermal radiometry technique based on Xe illumination was applied in CER disks 600 μm thick for heating, with prepared in four particle sizes (25, 38, 45, and 53) μm, which were added microemulsion gel with variation volumes (140, 150, 160, and 170) μl. The behavior of the thermal diffusivity CER disks shows linear decay for increase emulsion volume, and in contrast, thermal diffusivity increases with particles sizes. Aiming to compare to MTA, thermal properties of CER were averaged to get the figure of merit for thermal diffusivity as (44.2 ± 3.6) × 10-3 cm2/s, for thermal conductivity (228 ± 32) mW/cm K, the thermal effusivity (1.09 ± 0.06) W s0.5/cm2 K and volume heat capacity (5.2 ± 0.7) J/cm3 K, which are in excellent agreement with results of a disk prepared from commercial MTA-Angelus (grain size < 10 μm using 57 μl of distilled water).

  3. Non-destructive thermal wave method applied to study thermal properties of fast setting time endodontic cement

    SciTech Connect

    Picolloto, A. M.; Mariucci, V. V. G.; Szpak, W.; Medina, A. N.; Baesso, M. L.; Astrath, N. G. C.; Astrath, F. B. G.; Bento, A. C.; Santos, A. D.; Moraes, J. C. S.

    2013-11-21

    The thermal wave method is applied for thermal properties measurement in fast endodontic cement (CER). This new formula is developed upon using Portland cement in gel and it was successfully tested in mice with good biocompatibility and stimulated mineralization. Recently, thermal expansion and setting time were measured, conferring to this material twice faster hardening than the well known Angelus Mineral trioxide aggregate (MTA) the feature of fast hardening (∼7 min) and with similar thermal expansion (∼12 μstrain/ °C). Therefore, it is important the knowledge of thermal properties like thermal diffusivity, conductivity, effusivity in order to match thermally the tissue environment upon its application in filling cavities of teeth. Photothermal radiometry technique based on Xe illumination was applied in CER disks 600 μm thick for heating, with prepared in four particle sizes (25, 38, 45, and 53) μm, which were added microemulsion gel with variation volumes (140, 150, 160, and 170) μl. The behavior of the thermal diffusivity CER disks shows linear decay for increase emulsion volume, and in contrast, thermal diffusivity increases with particles sizes. Aiming to compare to MTA, thermal properties of CER were averaged to get the figure of merit for thermal diffusivity as (44.2 ± 3.6) × 10{sup −3} cm{sup 2}/s, for thermal conductivity (228 ± 32) mW/cm K, the thermal effusivity (1.09 ± 0.06) W s{sup 0.5}/cm{sup 2} K and volume heat capacity (5.2 ± 0.7) J/cm{sup 3} K, which are in excellent agreement with results of a disk prepared from commercial MTA-Angelus (grain size < 10 μm using 57 μl of distilled water)

  4. Experimental demonstration of a real-time high-throughput digital DC blocker for compensating ADC imperfections in optical fast-OFDM receivers.

    PubMed

    Zhang, Lu; Ouyang, Xing; Shao, Xiaopeng; Zhao, Jian

    2016-06-27

    Performance degradation induced by the DC components at the output of real-time analogue-to-digital converter (ADC) is experimentally investigated for optical fast-OFDM receiver. To compensate this degradation, register transfer level (RTL) circuits for real-time digital DC blocker with 20GS/s throughput are proposed and implemented in field programmable gate array (FPGA). The performance of the proposed real-time digital DC blocker is experimentally investigated in a 15Gb/s optical fast-OFDM system with intensity modulation and direct detection over 40 km standard single-mode fibre. The results show that the fixed-point DC blocker has negligible performance penalty compared to the offline floating point one, and can overcome the error floor of the fast OFDM receiver caused by the DC components from the real-time ADC output. PMID:27410579

  5. A fast chopper for medium energy beams

    NASA Astrophysics Data System (ADS)

    Madrak, R.; Wildman, D.

    2014-10-01

    The key elements have been constructed for a fast chopper system capable of removing single 2.5 MeV proton bunches spaced at 325 MHz. The average chopping rate is ~ 1 MHz. The components include a pulse delaying microstrip structure for deflecting the beam, high voltage (1.2 kV) fast (ns rise time) pulsers, and an associated wideband combiner. Various designs for the deflecting structures have been studied. Measurements of the microstrip structures' coverage factors and pulse shapes are presented.

  6. Numerical model for atmospheric contaminant cloud rise scenarios

    NASA Astrophysics Data System (ADS)

    Kanarska, Yuliya; Lomov, Ilya; Antoun, Tarabay; Glenn, Lewis

    2007-11-01

    Our numerical approach includes fluid mechanical model which is the combination of a compressible GEODYN code and a Low Mach code (LMC). The first one is an explicit code and it is intended to simulate early stages of nuclear explosions up to 15 s. The second one is an implicit code based on a pressure projection method and it is intended to simulate subsequent cloud rise events up to few hours. We perform series of cloud rise scenarios ranging from idealized bubble rise problem to realistic air bursts. We analyze effects of compressible dynamics and different turbulent parameterizations on the cloud evolution. It is found that in a realistic configuration interaction of a reflected shock wave from the ground with a fireball affects significantly cloud evolution in contrast to idealized bubble rise simulations. We show that by providing initial source from compressible GEODYN code, later times flow evolution can be successfully simulated with fast and efficient LMC code. Finally, we develop formalism for tracer particles and their fallout and present some preliminary results.

  7. Fast pulse nonthermal plasma reactor

    DOEpatents

    Rosocha, Louis A.

    2005-06-14

    A fast pulsed nonthermal plasma reactor includes a discharge cell and a charging assembly electrically connected thereto. The charging assembly provides plural high voltage pulses to the discharge cell. Each pulse has a rise time between one and ten nanoseconds and a duration of three to twenty nanoseconds. The pulses create nonthermal plasma discharge within the discharge cell. Accordingly, the nonthermal plasma discharge can be used to remove pollutants from gases or break the gases into smaller molecules so that they can be more efficiently combusted.

  8. Perceptual Temporal Asymmetry Associated with Distinct ON and OFF Responses to Time-Varying Sounds with Rising versus Falling Intensity: A Magnetoencephalography Study.

    PubMed

    Zhang, Yang; Cheng, Bing; Koerner, Tess K; Schlauch, Robert S; Tanaka, Keita; Kawakatsu, Masaki; Nemoto, Iku; Imada, Toshiaki

    2016-01-01

    This magnetoencephalography (MEG) study investigated evoked ON and OFF responses to ramped and damped sounds in normal-hearing human adults. Two pairs of stimuli that differed in spectral complexity were used in a passive listening task; each pair contained identical acoustical properties except for the intensity envelope. Behavioral duration judgment was conducted in separate sessions, which replicated the perceptual bias in favour of the ramped sounds and the effect of spectral complexity on perceived duration asymmetry. MEG results showed similar cortical sites for the ON and OFF responses. There was a dominant ON response with stronger phase-locking factor (PLF) in the alpha (8-14 Hz) and theta (4-8 Hz) bands for the damped sounds. In contrast, the OFF response for sounds with rising intensity was associated with stronger PLF in the gamma band (30-70 Hz). Exploratory correlation analysis showed that the OFF response in the left auditory cortex was a good predictor of the perceived temporal asymmetry for the spectrally simpler pair. The results indicate distinct asymmetry in ON and OFF responses and neural oscillation patterns associated with the dynamic intensity changes, which provides important preliminary data for future studies to examine how the auditory system develops such an asymmetry as a function of age and learning experience and whether the absence of asymmetry or abnormal ON and OFF responses can be taken as a biomarker for certain neurological conditions associated with auditory processing deficits. PMID:27527227

  9. High-speed real-time magnetic resonance imaging of fast tongue movements in elite horn players

    PubMed Central

    Voit, Dirk; Joseph, Arun A.; Schoonderwaldt, Erwin; Altenmüller, Eckart

    2015-01-01

    This paper describes the use of high-speed real-time (RT) magnetic resonance imaging (MRI) in quantifying very rapid motor function within the oropharyngeal cavity of six elite horn players. Based on simultaneous sound recordings, the efficacy of RT-MRI films at 30 and 100 frames per second (fps) was assessed for tongue movements associated with double tonguing performance. Serial images with a nominal temporal resolution of 10.0 and 33.3 ms were obtained by highly undersampled radial fast low-angle shot (FLASH) sequences (5 and 17 spokes, respectively) using complementary sets of spokes for successive acquisitions (extending over 9 and 5 frames, respectively). Reconstructions of high-speed images were obtained by temporally regularized nonlinear inversion (NLINV) as previously described. A customized MATLAB toolkit was developed for the extraction of line profiles from MRI films to quantify temporal phenomena associated with task performance. The analyses reveal that for the present setting, which required the use of a temporal median filter to optimize image quality, acquisition rates of 30 fps are inadequate to accurately detect tongue movements during double tonguing, but that rates of 100 fps do allow for a precise quantification of movement. These data for the first time demonstrate the extreme performance of elite horn players. High-speed RT-MRI offers so far unavailable opportunities to study the oropharyngeal movements during brass playing with future potential for teaching and the treatment of patients suffering from dystonia. PMID:26029640

  10. Mixed-element Octree: a meshing technique toward fast and real-time simulations in biomedical applications.

    PubMed

    Lobos, Claudio; González, Eugenio

    2015-12-01

    This article introduces a meshing technique focused on fast and real-time simulation in a biomedical context. We describe in details our algorithm, which starts from a basic Octree regarding the constraints imposed by the simulation, and then, mixed-element patterns are applied over transitions between coarse and fine regions. The use of surface patterns, also composed by mixed elements, allows us to better represent curved domains decreasing the odds of creating invalid elements by adding as few nodes as possible. In contrast with other meshing techniques, we let the user define regions of greater refinement, and as a consequence of that refinement, we add as few nodes as possible to produce a mesh that is topologically correct. Therefore, our meshing technique gives more control on the number of nodes of the final mesh. We show several examples where the quality of the final mesh is acceptable, even without using quality filters. We believe that this new meshing technique is in the correct direction toward real-time simulation in the biomedical field. PMID:26011778

  11. High-speed real-time magnetic resonance imaging of fast tongue movements in elite horn players.

    PubMed

    Iltis, Peter W; Frahm, Jens; Voit, Dirk; Joseph, Arun A; Schoonderwaldt, Erwin; Altenmüller, Eckart

    2015-06-01

    This paper describes the use of high-speed real-time (RT) magnetic resonance imaging (MRI) in quantifying very rapid motor function within the oropharyngeal cavity of six elite horn players. Based on simultaneous sound recordings, the efficacy of RT-MRI films at 30 and 100 frames per second (fps) was assessed for tongue movements associated with double tonguing performance. Serial images with a nominal temporal resolution of 10.0 and 33.3 ms were obtained by highly undersampled radial fast low-angle shot (FLASH) sequences (5 and 17 spokes, respectively) using complementary sets of spokes for successive acquisitions (extending over 9 and 5 frames, respectively). Reconstructions of high-speed images were obtained by temporally regularized nonlinear inversion (NLINV) as previously described. A customized MATLAB toolkit was developed for the extraction of line profiles from MRI films to quantify temporal phenomena associated with task performance. The analyses reveal that for the present setting, which required the use of a temporal median filter to optimize image quality, acquisition rates of 30 fps are inadequate to accurately detect tongue movements during double tonguing, but that rates of 100 fps do allow for a precise quantification of movement. These data for the first time demonstrate the extreme performance of elite horn players. High-speed RT-MRI offers so far unavailable opportunities to study the oropharyngeal movements during brass playing with future potential for teaching and the treatment of patients suffering from dystonia. PMID:26029640

  12. SeaMon-HC Buoy. A specific real-time-lightweight-moored platform as a tool for fast hydrocarbon detection

    NASA Astrophysics Data System (ADS)

    Barrera, C.; Rueda, M. J.; Moran, R.; Llerandi, C.; Llinas, O.

    2009-04-01

    The present paper-work describes the design, last development stages and the derived results from a specific buoy platform for fast hydrocarbon detection in seawater. Under the name of SeaMon-HC, (Patent No. P200302219/8) the buoy represents a very chief tool for coastal monitoring, mainly surrounding areas with a high oil-spill risk level, like harbours, off-shore fish farming, beaches and so on. Nowadays, the Macaronesian area has nine units working in real-time, under the frame of the Red ACOMAR Network. The main innovative aspect from this buoy is the detection system. It's based in polymer technology, working as a resistance, who increase its value when the pollutant on water surface is detected. The response time from the sensor is a direct function of the hydrocarbon volatility level. For hydrocarbons with high volatility levels (like petrol), the sensor needs less time (around 3 minutes) than others with less volatility such as oils. SeaMon-HC is an autonomous, modular, reusable and a very low-cost development integrated by four subsystems (SS): SS-Flotation (different materials and shapes available); SS-Sensors (hydrocarbon detector and additional sensors -up to 15-, to solve specific sensor configuration requirements); SS-Power Supply (equipped in its basic configuration with a couple of solar modules and two 12V batteries) and the SS-Communication (based on a RF or GSM/GPRS modem technology, with a selectable communication frequency). All SeaMon-HC units, as well the rest of the ODAS buoys who joint together the Red ACOMAR Network, works in real-time, sending the collected information to the control centre that manages the communications, providing data, in a useful form (as a web site), to diverse socio-economic important sectors which make an exhaustive use of the littoral in the Macaronesian region. The access to the information by the users is done through a specific GIS software application.

  13. Ultra-fast formation control of high-order discrete-time multi-agent systems based on multi-step predictive mechanism.

    PubMed

    Zhang, Wenle; Liu, Jianchang; Wang, Honghai

    2015-09-01

    This paper deals with the ultra-fast formation control problem of high-order discrete-time multi-agent systems. Using the local neighbor-error knowledge, a novel ultra-fast protocol with multi-step predictive information and self-feedback term is proposed. The asymptotic convergence factor is improved by a power of q+1 compared to the routine protocol. To some extent, the ultra-fast algorithm overcomes the influence of communication topology to the convergence speed. Furthermore, some sufficient conditions are given herein. The ones decouple the design of the synchronizing gains from the detailed graph properties, and explicitly reveal how the agent dynamic and the communication graph jointly affect the ultra-fast formationability. Finally, some simulations are worked out to illustrate the effectiveness of our theoretical results. PMID:26051965

  14. Polycrystalline CVD diamond detector: Fast response and high sensitivity with large area

    SciTech Connect

    Liu, Linyue Zhang, Xianpeng; Zhong, Yunhong; Ouyang, Xiaoping Zhang, Jianfu

    2014-01-15

    Polycrystalline diamond was successfully used to fabricate a large area (diameter up to 46 mm) radiation detector. It was proven that the developed detector shows a fast pulsed response time and a high sensitivity, therefore its rise time is lower than 5 ns, which is two times faster than that of a Si-PIN detector of the same size. And because of the large sensitive area, this detector shows good dominance in fast pulsed and low density radiation detection.

  15. The influence of market deregulation on fast food consumption and body mass index: a cross-national time series analysis

    PubMed Central

    Kouvonen, Anne; Gimeno, David

    2014-01-01

    Abstract Objective To investigate the effect of fast food consumption on mean population body mass index (BMI) and explore the possible influence of market deregulation on fast food consumption and BMI. Methods The within-country association between fast food consumption and BMI in 25 high-income member countries of the Organisation for Economic Co-operation and Development between 1999 and 2008 was explored through multivariate panel regression models, after adjustment for per capita gross domestic product, urbanization, trade openness, lifestyle indicators and other covariates. The possible mediating effect of annual per capita intake of soft drinks, animal fats and total calories on the association between fast food consumption and BMI was also analysed. Two-stage least squares regression models were conducted, using economic freedom as an instrumental variable, to study the causal effect of fast food consumption on BMI. Findings After adjustment for covariates, each 1-unit increase in annual fast food transactions per capita was associated with an increase of 0.033 kg/m2 in age-standardized BMI (95% confidence interval, CI: 0.013–0.052). Only the intake of soft drinks – not animal fat or total calories – mediated the observed association (β: 0.030; 95% CI: 0.010–0.050). Economic freedom was an independent predictor of fast food consumption (β: 0.27; 95% CI: 0.16–0.37). When economic freedom was used as an instrumental variable, the association between fast food and BMI weakened but remained significant (β: 0.023; 95% CI: 0.001–0.045). Conclusion Fast food consumption is an independent predictor of mean BMI in high-income countries. Market deregulation policies may contribute to the obesity epidemic by facilitating the spread of fast food. PMID:24623903

  16. Very high pressure liquid chromatography using fully porous particles: quantitative analysis of fast gradient separations without post-run times.

    PubMed

    Stankovich, Joseph J; Gritti, Fabrice; Stevenson, Paul G; Beaver, Lois Ann; Guiochon, Georges

    2014-01-10

    Using a column packed with fully porous particles, four methods for controlling the flow rates at which gradient elution runs are conducted in very high pressure liquid chromatography (VHPLC) were tested to determine whether reproducible thermal conditions could be achieved, such that subsequent analyses would proceed at nearly the same initial temperature. In VHPLC high flow rates are achieved, producing fast analyses but requiring high inlet pressures. The combination of high flow rates and high inlet pressures generates local heat, leading to temperature changes in the column. Usually in this case a post-run time is input into the analytical method to allow the return of the column temperature to its initial state. An alternative strategy involves operating the column without a post-run equilibration period and maintaining constant temperature variations for subsequent analysis after conducting one or a few separations to bring the column to a reproducible starting temperature. A liquid chromatography instrument equipped with a pressure controller was used to perform constant pressure and constant flow rate VHPLC separations. Six replicate gradient separations of a nine component mixture consisting of acetophenone, propiophenone, butyrophenone, valerophenone, hexanophenone, heptanophenone, octanophenone, benzophenone, and acetanilide dissolved in water/acetonitrile (65:35, v/v) were performed under various experimental conditions: constant flow rate, two sets of constant pressure, and constant pressure operation with a programmed flow rate. The relative standard deviations of the response factors for all the analytes are lower than 5% across the methods. Programming the flow rate to maintain a fairly constant pressure instead of using instrument controlled constant pressure improves the reproducibility of the retention times by a factor of 5, when plotting the chromatograms in time. PMID:24296292

  17. A method to fast position the trigger time scale of non-cable seismographs based on controllable vibrator

    NASA Astrophysics Data System (ADS)

    Zheng, F.; Lin, J.; Chen, Z.; Zhang, L.; Huaizhu, Z.; Yang, H.

    2011-12-01

    , controls the wireless data communication module, transmits to the host the aggregated trigger time scale information, scanning duration and the reference signals. Field experiments have shown that, the proposed method can effectively obtain trigger time scale and reference signals of seismic data, allowing for fast and accurate positioning of effective seismic data during data transmission. It saves a substantial amount of transmission time and storage space, and spares a lot of manpower and other resources by its automated processing method.

  18. Fast Pyrolysis Behavior of Banagrass as a Function of Temperature and Volatiles Residence Time in a Fluidized Bed Reactor

    PubMed Central

    Morgan, Trevor James; Turn, Scott Q.; George, Anthe

    2015-01-01

    A reactor was designed and commissioned to study the fast pyrolysis behavior of banagrass as a function of temperature and volatiles residence time. Four temperatures between 400 and 600°C were examined as well as four residence times between ~1.0 and 10 seconds. Pyrolysis product distributions of bio-oil, char and permanent gases were determined at each reaction condition. The elemental composition of the bio-oils and chars was also assessed. The greatest bio-oil yield was recorded when working at 450°C with a volatiles residence time of 1.4 s, ~37 wt% relative to the dry ash free feedstock (excluding pyrolysis water). The amounts of char (organic fraction) and permanent gases under these conditions are ~4 wt% and 8 wt% respectively. The bio-oil yield stated above is for 'dry' bio-oil after rotary evaporation to remove solvent, which results in volatiles and pyrolysis water being removed from the bio-oil. The material removed during drying accounts for the remainder of the pyrolysis products. The 'dry' bio-oil produced under these conditions contains ~56 wt% carbon which is ~40 wt% of the carbon present in the feedstock. The oxygen content of the 450°C, 1.4 s 'dry' bio-oil is ~38 wt%, which accounts for ~33 wt% of the oxygen in the feedstock. At higher temperature or longer residence time less bio-oil and char is recovered and more gas and light volatiles are produced. Increasing the temperature has a more significant effect on product yields and composition than increasing the volatiles residence time. At 600°C and a volatiles residence time of 1.2 seconds the bio-oil yield is ~21 wt% of the daf feedstock, with a carbon content of 64 wt% of the bio-oil. The bio-oil yield from banagrass is significantly lower than from woody biomass or grasses such as switchgrass or miscanthus, but is similar to barley straw. The reason for the low bio-oil yield from banagrass is thought to be related to its high ash content (8.5 wt% dry basis) and high concentration of alkali

  19. Fast Pyrolysis Behavior of Banagrass as a Function of Temperature and Volatiles Residence Time in a Fluidized Bed Reactor

    DOE PAGESBeta

    Morgan, Trevor James; Turn, Scott Q.; George, Anthe

    2015-08-26

    A reactor was designed and commissioned to study the fast pyrolysis behavior of banagrass as a function of temperature and volatiles residence time. Four temperatures between 400 and 600°C were examined as well as four residence times between ~1.0 and 10 seconds. Pyrolysis product distributions of bio-oil, char and permanent gases were determined at each reaction condition. The elemental composition of the bio-oils and chars was also assessed. The greatest bio-oil yield was recorded when working at 450°C with a volatiles residence time of 1.4 s, ~37 wt% relative to the dry ash free feedstock (excluding pyrolysis water). The amountsmore » of char (organic fraction) and permanent gases under these conditions are ~4 wt% and 8 wt% respectively. The bio-oil yield stated above is for 'dry' bio-oil after rotary evaporation to remove solvent, which results in volatiles and pyrolysis water being removed from the bio-oil. The material removed during drying accounts for the remainder of the pyrolysis products. The 'dry' bio-oil produced under these conditions contains ~56 wt% carbon which is ~40 wt% of the carbon present in the feedstock. The oxygen content of the 450°C, 1.4 s 'dry' bio-oil is ~38 wt%, which accounts for ~33 wt% of the oxygen in the feedstock. At higher temperature or longer residence time less bio-oil and char is recovered and more gas and light volatiles are produced. Increasing the temperature has a more significant effect on product yields and composition than increasing the volatiles residence time. At 600°C and a volatiles residence time of 1.2 seconds the bio-oil yield is ~21 wt% of the daf feedstock, with a carbon content of 64 wt% of the bio-oil. The bio-oil yield from banagrass is significantly lower than from woody biomass or grasses such as switchgrass or miscanthus, but is similar to barley straw. In conclusion, the reason for the low bio-oil yield from banagrass is thought to be related to its high ash content (8.5 wt% dry basis) and high

  20. Fast Pyrolysis Behavior of Banagrass as a Function of Temperature and Volatiles Residence Time in a Fluidized Bed Reactor.

    PubMed

    Morgan, Trevor James; Turn, Scott Q; George, Anthe

    2015-01-01

    A reactor was designed and commissioned to study the fast pyrolysis behavior of banagrass as a function of temperature and volatiles residence time. Four temperatures between 400 and 600°C were examined as well as four residence times between ~1.0 and 10 seconds. Pyrolysis product distributions of bio-oil, char and permanent gases were determined at each reaction condition. The elemental composition of the bio-oils and chars was also assessed. The greatest bio-oil yield was recorded when working at 450°C with a volatiles residence time of 1.4 s, ~37 wt% relative to the dry ash free feedstock (excluding pyrolysis water). The amounts of char (organic fraction) and permanent gases under these conditions are ~4 wt% and 8 wt% respectively. The bio-oil yield stated above is for 'dry' bio-oil after rotary evaporation to remove solvent, which results in volatiles and pyrolysis water being removed from the bio-oil. The material removed during drying accounts for the remainder of the pyrolysis products. The 'dry' bio-oil produced under these conditions contains ~56 wt% carbon which is ~40 wt% of the carbon present in the feedstock. The oxygen content of the 450°C, 1.4 s 'dry' bio-oil is ~38 wt%, which accounts for ~33 wt% of the oxygen in the feedstock. At higher temperature or longer residence time less bio-oil and char is recovered and more gas and light volatiles are produced. Increasing the temperature has a more significant effect on product yields and composition than increasing the volatiles residence time. At 600°C and a volatiles residence time of 1.2 seconds the bio-oil yield is ~21 wt% of the daf feedstock, with a carbon content of 64 wt% of the bio-oil. The bio-oil yield from banagrass is significantly lower than from woody biomass or grasses such as switchgrass or miscanthus, but is similar to barley straw. The reason for the low bio-oil yield from banagrass is thought to be related to its high ash content (8.5 wt% dry basis) and high concentration of alkali

  1. Fast Pyrolysis Behavior of Banagrass as a Function of Temperature and Volatiles Residence Time in a Fluidized Bed Reactor

    SciTech Connect

    Morgan, Trevor James; Turn, Scott Q.; George, Anthe

    2015-08-26

    A reactor was designed and commissioned to study the fast pyrolysis behavior of banagrass as a function of temperature and volatiles residence time. Four temperatures between 400 and 600°C were examined as well as four residence times between ~1.0 and 10 seconds. Pyrolysis product distributions of bio-oil, char and permanent gases were determined at each reaction condition. The elemental composition of the bio-oils and chars was also assessed. The greatest bio-oil yield was recorded when working at 450°C with a volatiles residence time of 1.4 s, ~37 wt% relative to the dry ash free feedstock (excluding pyrolysis water). The amounts of char (organic fraction) and permanent gases under these conditions are ~4 wt% and 8 wt% respectively. The bio-oil yield stated above is for 'dry' bio-oil after rotary evaporation to remove solvent, which results in volatiles and pyrolysis water being removed from the bio-oil. The material removed during drying accounts for the remainder of the pyrolysis products. The 'dry' bio-oil produced under these conditions contains ~56 wt% carbon which is ~40 wt% of the carbon present in the feedstock. The oxygen content of the 450°C, 1.4 s 'dry' bio-oil is ~38 wt%, which accounts for ~33 wt% of the oxygen in the feedstock. At higher temperature or longer residence time less bio-oil and char is recovered and more gas and light volatiles are produced. Increasing the temperature has a more significant effect on product yields and composition than increasing the volatiles residence time. At 600°C and a volatiles residence time of 1.2 seconds the bio-oil yield is ~21 wt% of the daf feedstock, with a carbon content of 64 wt% of the bio-oil. The bio-oil yield from banagrass is significantly lower than from woody biomass or grasses such as switchgrass or miscanthus, but is similar to barley straw. In conclusion, the reason for the low bio-oil yield from banagrass is thought to be related to its high ash content (8.5 wt% dry basis) and high

  2. Time-resolved compression of a capsule with a cone to high density for fast-ignition laser fusion

    DOE PAGESBeta

    Theobald, W.; Solodov, A. A.; Stoeckl, C.; Anderson, K. S.; Beg, F. N.; Epstein, R.; Fiksel, G.; Giraldez, E. M.; Glebov, V. Yu.; Habara, H.; et al

    2014-12-12

    The advent of high-intensity lasers enables us to recreate and study the behaviour of matter under the extreme densities and pressures that exist in many astrophysical objects. It may also enable us to develop a power source based on laser-driven nuclear fusion. Achieving such conditions usually requires a target that is highly uniform and spherically symmetric. Here we show that it is possible to generate high densities in a so-called fast-ignition target that consists of a thin shell whose spherical symmetry is interrupted by the inclusion of a metal cone. Using picosecond-time-resolved X-ray radiography, we show that we can achievemore » areal densities in excess of 300 mg cm -2 with a nanosecond-duration compression pulse -- the highest areal density ever reported for a cone-in-shell target. Such densities are high enough to stop MeV electrons, which is necessary for igniting the fuel with a subsequent picosecond pulse focused into the resulting plasma.« less

  3. Time-resolved compression of a capsule with a cone to high density for fast-ignition laser fusion

    NASA Astrophysics Data System (ADS)

    Theobald, W.; Solodov, A. A.; Stoeckl, C.; Anderson, K. S.; Beg, F. N.; Epstein, R.; Fiksel, G.; Giraldez, E. M.; Glebov, V. Yu.; Habara, H.; Ivancic, S.; Jarrott, L. C.; Marshall, F. J.; McKiernan, G.; McLean, H. S.; Mileham, C.; Nilson, P. M.; Patel, P. K.; Pérez, F.; Sangster, T. C.; Santos, J. J.; Sawada, H.; Shvydky, A.; Stephens, R. B.; Wei, M. S.

    2014-12-01

    The advent of high-intensity lasers enables us to recreate and study the behaviour of matter under the extreme densities and pressures that exist in many astrophysical objects. It may also enable us to develop a power source based on laser-driven nuclear fusion. Achieving such conditions usually requires a target that is highly uniform and spherically symmetric. Here we show that it is possible to generate high densities in a so-called fast-ignition target that consists of a thin shell whose spherical symmetry is interrupted by the inclusion of a metal cone. Using picosecond-time-resolved X-ray radiography, we show that we can achieve areal densities in excess of 300 mg cm-2 with a nanosecond-duration compression pulse—the highest areal density ever reported for a cone-in-shell target. Such densities are high enough to stop MeV electrons, which is necessary for igniting the fuel with a subsequent picosecond pulse focused into the resulting plasma.

  4. Time-resolved compression of a capsule with a cone to high density for fast-ignition laser fusion

    SciTech Connect

    Theobald, W.; Solodov, A. A.; Stoeckl, C.; Anderson, K. S.; Beg, F. N.; Epstein, R.; Fiksel, G.; Giraldez, E. M.; Glebov, V. Yu.; Habara, H.; Ivancic, S.; Jarrott, L. C.; Marshall, F. J.; McKiernan, G.; McLean, H. S.; Mileham, C.; Nilson, P. M.; Patel, P. K.; Pérez, F.; Sangster, T. C.; Santos, J. J.; Sawada, H.; Shvydky, A.; Stephens, R. B.; Wei, M. S.

    2014-12-12

    The advent of high-intensity lasers enables us to recreate and study the behaviour of matter under the extreme densities and pressures that exist in many astrophysical objects. It may also enable us to develop a power source based on laser-driven nuclear fusion. Achieving such conditions usually requires a target that is highly uniform and spherically symmetric. Here we show that it is possible to generate high densities in a so-called fast-ignition target that consists of a thin shell whose spherical symmetry is interrupted by the inclusion of a metal cone. Using picosecond-time-resolved X-ray radiography, we show that we can achieve areal densities in excess of 300 mg cm -2 with a nanosecond-duration compression pulse -- the highest areal density ever reported for a cone-in-shell target. Such densities are high enough to stop MeV electrons, which is necessary for igniting the fuel with a subsequent picosecond pulse focused into the resulting plasma.

  5. Fast, multi-channel real-time processing of signals with microsecond latency using graphics processing units

    NASA Astrophysics Data System (ADS)

    Rath, N.; Kato, S.; Levesque, J. P.; Mauel, M. E.; Navratil, G. A.; Peng, Q.

    2014-04-01

    Fast, digital signal processing (DSP) has many applications. Typical hardware options for performing DSP are field-programmable gate arrays (FPGAs), application-specific integrated DSP chips, or general purpose personal computer systems. This paper presents a novel DSP platform that has been developed for feedback control on the HBT-EP tokamak device. The system runs all signal processing exclusively on a Graphics Processing Unit (GPU) to achieve real-time performance with latencies below 8 μs. Signals are transferred into and out of the GPU using PCI Express peer-to-peer direct-memory-access transfers without involvement of the central processing unit or host memory. Tests were performed on the feedback control system of the HBT-EP tokamak using forty 16-bit floating point inputs and outputs each and a sampling rate of up to 250 kHz. Signals were digitized by a D-TACQ ACQ196 module, processing done on an NVIDIA GTX 580 GPU programmed in CUDA, and analog output was generated by D-TACQ AO32CPCI modules.

  6. Time-resolved compression of a capsule with a cone to high density for fast-ignition laser fusion.

    PubMed

    Theobald, W; Solodov, A A; Stoeckl, C; Anderson, K S; Beg, F N; Epstein, R; Fiksel, G; Giraldez, E M; Glebov, V Yu; Habara, H; Ivancic, S; Jarrott, L C; Marshall, F J; McKiernan, G; McLean, H S; Mileham, C; Nilson, P M; Patel, P K; Pérez, F; Sangster, T C; Santos, J J; Sawada, H; Shvydky, A; Stephens, R B; Wei, M S

    2014-01-01

    The advent of high-intensity lasers enables us to recreate and study the behaviour of matter under the extreme densities and pressures that exist in many astrophysical objects. It may also enable us to develop a power source based on laser-driven nuclear fusion. Achieving such conditions usually requires a target that is highly uniform and spherically symmetric. Here we show that it is possible to generate high densities in a so-called fast-ignition target that consists of a thin shell whose spherical symmetry is interrupted by the inclusion of a metal cone. Using picosecond-time-resolved X-ray radiography, we show that we can achieve areal densities in excess of 300 mg cm(-2) with a nanosecond-duration compression pulse--the highest areal density ever reported for a cone-in-shell target. Such densities are high enough to stop MeV electrons, which is necessary for igniting the fuel with a subsequent picosecond pulse focused into the resulting plasma. PMID:25503788

  7. Fast, multi-channel real-time processing of signals with microsecond latency using graphics processing units.

    PubMed

    Rath, N; Kato, S; Levesque, J P; Mauel, M E; Navratil, G A; Peng, Q

    2014-04-01

    Fast, digital signal processing (DSP) has many applications. Typical hardware options for performing DSP are field-programmable gate arrays (FPGAs), application-specific integrated DSP chips, or general purpose personal computer systems. This paper presents a novel DSP platform that has been developed for feedback control on the HBT-EP tokamak device. The system runs all signal processing exclusively on a Graphics Processing Unit (GPU) to achieve real-time performance with latencies below 8 μs. Signals are transferred into and out of the GPU using PCI Express peer-to-peer direct-memory-access transfers without involvement of the central processing unit or host memory. Tests were performed on the feedback control system of the HBT-EP tokamak using forty 16-bit floating point inputs and outputs each and a sampling rate of up to 250 kHz. Signals were digitized by a D-TACQ ACQ196 module, processing done on an NVIDIA GTX 580 GPU programmed in CUDA, and analog output was generated by D-TACQ AO32CPCI modules. PMID:24784666

  8. Fast, multi-channel real-time processing of signals with microsecond latency using graphics processing units

    SciTech Connect

    Rath, N. Levesque, J. P.; Mauel, M. E.; Navratil, G. A.; Peng, Q.; Kato, S.

    2014-04-15

    Fast, digital signal processing (DSP) has many applications. Typical hardware options for performing DSP are field-programmable gate arrays (FPGAs), application-specific integrated DSP chips, or general purpose personal computer systems. This paper presents a novel DSP platform that has been developed for feedback control on the HBT-EP tokamak device. The system runs all signal processing exclusively on a Graphics Processing Unit (GPU) to achieve real-time performance with latencies below 8 μs. Signals are transferred into and out of the GPU using PCI Express peer-to-peer direct-memory-access transfers without involvement of the central processing unit or host memory. Tests were performed on the feedback control system of the HBT-EP tokamak using forty 16-bit floating point inputs and outputs each and a sampling rate of up to 250 kHz. Signals were digitized by a D-TACQ ACQ196 module, processing done on an NVIDIA GTX 580 GPU programmed in CUDA, and analog output was generated by D-TACQ AO32CPCI modules.

  9. Accurate, Fast and Cost-Effective Diagnostic Test for Monosomy 1p36 Using Real-Time Quantitative PCR

    PubMed Central

    Cunha, Pricila da Silva; Pena, Heloisa B.; D'Angelo, Carla Sustek; Koiffmann, Celia P.; Rosenfeld, Jill A.; Shaffer, Lisa G.; Stofanko, Martin; Gonçalves-Dornelas, Higgor; Pena, Sérgio Danilo Junho

    2014-01-01

    Monosomy 1p36 is considered the most common subtelomeric deletion syndrome in humans and it accounts for 0.5–0.7% of all the cases of idiopathic intellectual disability. The molecular diagnosis is often made by microarray-based comparative genomic hybridization (aCGH), which has the drawback of being a high-cost technique. However, patients with classic monosomy 1p36 share some typical clinical characteristics that, together with its common prevalence, justify the development of a less expensive, targeted diagnostic method. In this study, we developed a simple, rapid, and inexpensive real-time quantitative PCR (qPCR) assay for targeted diagnosis of monosomy 1p36, easily accessible for low-budget laboratories in developing countries. For this, we have chosen two target genes which are deleted in the majority of patients with monosomy 1p36: PRKCZ and SKI. In total, 39 patients previously diagnosed with monosomy 1p36 by aCGH, fluorescent in situ hybridization (FISH), and/or multiplex ligation-dependent probe amplification (MLPA) all tested positive on our qPCR assay. By simultaneously using these two genes we have been able to detect 1p36 deletions with 100% sensitivity and 100% specificity. We conclude that qPCR of PRKCZ and SKI is a fast and accurate diagnostic test for monosomy 1p36, costing less than 10 US dollars in reagent costs. PMID:24839341

  10. Real-time fast inverse dose optimization for image guided adaptive radiation therapy-Enhancements to fast inverse dose optimization (FIDO)

    NASA Astrophysics Data System (ADS)

    Goldman, S. P.; Turnbull, D.; Johnson, C.; Chen, J. Z.; Battista, J. J.

    2009-05-01

    A fast, accurate and stable optimization algorithm is very important for inverse planning of intensity-modulated radiation therapy (IMRT), and for implementing dose-adaptive radiotherapy in the future. Conventional numerical search algorithms with positive beam weight constraints generally require numerous iterations and may produce suboptimal dose results due to trapping in local minima regions of the objective function landscape. A direct solution of the inverse problem using conventional quadratic objective functions without positive beam constraints is more efficient but it will result in unrealistic negative beam weights. We review here a direct solution of the inverse problem that is efficient and does not yield unphysical negative beam weights. In fast inverse dose optimization (FIDO) method the objective function for the optimization of a large number of beamlets is reformulated such that the optimization problem is reducible to a linear set of equations. The optimal set of intensities is then found through a matrix inversion, and negative beamlet intensities are avoided without the need for externally imposed ad hoc conditions. In its original version [S. P. Goldman, J. Z. Chen, and J. J. Battista, in Proceedings of the XIVth International Conference on the Use of Computers in Radiation Therapy, 2004, pp. 112-115; S. P. Goldman, J. Z. Chen, and J. J. Battista, Med. Phys. 32, 3007 (2005)], FIDO was tested on single two-dimensional computed tomography (CT) slices with sharp KERMA beams without scatter, in order to establish a proof of concept which demonstrated that FIDO could be a viable method for the optimization of cancer treatment plans. In this paper we introduce the latest advancements in FIDO that now include not only its application to three-dimensional volumes irradiated by beams with full scatter but include as well a complete implementation of clinical dose-volume constraints including maximum and minimum dose as well as equivalent uniform dose

  11. First-time Sliding Failure in Weak Sandstones and Subsequent Evolution in a Fast-moving Flow

    NASA Astrophysics Data System (ADS)

    Simoni, A.; Berti, M.; Bayer, B.; Bertello, L.; Franceschini, S.; Morandi, M. C.

    2014-12-01

    Following intense rainfalls, during spring 2013 a first-time sliding failure developed over a gentle cultivated slope in Northern Apennines. The slope is made of weakly cemented layered sandstones and subordinate siltstones and mudstones of Eocene age. The morphology is fairly regular with an average angle of 15° that increases up to 25° in the lower part of the slope where the pelitic fraction is no longer present in the bedrock succession. Bedding generally dips into the slope though the presence of faults locally complicate the setting. The sliding interested the upper, more gentle part of the slope with a maximum depth of 10 to 15 meters. Morphological evidences indicate a rotational component of movement and rocks outcropping along the scarp show a moderate degree of weathering. The main landslide body maintained its coherence and only a minor part of the toe mobilized as a fast-moving flow. No building nor infrastructure was affected by the movement but a railway viaduct is present in the lower part of the slope. Following the 2013 failure, movements and pore pressures were monitored in the landslide deposit to control the evolution of the phenomena. During the following winter, the abundant precipitation caused a reactivation of the movement that led to a much larger fast-moving flow. In this work, we document the sequence of events that has interested the slope during the years 2013-2014. Subsequent ground-based and aerial topographic surveys allow to estimate the volumes involved in the different phases of movement. Field evidences and investigations are used to interpret the geotechnical model of the slope and constrain the range of resistances mobilized at failure. The deformations preceding the 2014 reactivation are analyzed together with post-failure landslide deceleration. It is shown that displacements proceeded maintaining sustained moderate velocities for days before the catastrophic reactivation, making difficult to anticipate the acceleration

  12. A fast-time-response extreme ultraviolet spectrometer for measurement of impurity line emissions in the Experimental Advanced Superconducting Tokamak.

    PubMed

    Zhang, Ling; Morita, Shigeru; Xu, Zong; Wu, Zhenwei; Zhang, Pengfei; Wu, Chengrui; Gao, Wei; Ohishi, Tetsutarou; Goto, Motoshi; Shen, Junsong; Chen, Yingjie; Liu, Xiang; Wang, Yumin; Dong, Chunfeng; Zhang, Hongmin; Huang, Xianli; Gong, Xianzu; Hu, Liqun; Chen, Junlin; Zhang, Xiaodong; Wan, Baonian; Li, Jiangang

    2015-12-01

    A flat-field extreme ultraviolet (EUV) spectrometer working in the 20-500 Å wavelength range with fast time response has been newly developed to measure line emissions from highly ionized tungsten in the Experimental Advanced Superconducting Tokamak (EAST) with a tungsten divertor, while the monitoring of light and medium impurities is also an aim in the present development. A flat-field focal plane for spectral image detection is made by a laminar-type varied-line-spacing concave holographic grating with an angle of incidence of 87°. A back-illuminated charge-coupled device (CCD) with a total size of 26.6 × 6.6 mm(2) and pixel numbers of 1024 × 255 (26 × 26 μm(2)/pixel) is used for recording the focal image of spectral lines. An excellent spectral resolution of Δλ0 = 3-4 pixels, where Δλ0 is defined as full width at the foot position of a spectral line, is obtained at the 80-400 Å wavelength range after careful adjustment of the grating and CCD positions. The high signal readout rate of the CCD can improve the temporal resolution of time-resolved spectra when the CCD is operated in the full vertical binning mode. It is usually operated at 5 ms per frame. If the vertical size of the CCD is reduced with a narrow slit, the time response becomes faster. The high-time response in the spectral measurement therefore makes possible a variety of spectroscopic studies, e.g., impurity behavior in long pulse discharges with edge-localized mode bursts. An absolute intensity calibration of the EUV spectrometer is also carried out with a technique using the EUV bremsstrahlung continuum at 20-150 Å for quantitative data analysis. Thus, the high-time resolution tungsten spectra have been successfully observed with good spectral resolution using the present EUV spectrometer system. Typical tungsten spectra in the EUV wavelength range observed from EAST discharges are presented with absolute intensity and spectral identification. PMID:26724029

  13. A fast-time-response extreme ultraviolet spectrometer for measurement of impurity line emissions in the Experimental Advanced Superconducting Tokamak

    SciTech Connect

    Zhang, Ling; Xu, Zong; Wu, Zhenwei; Zhang, Pengfei; Wu, Chengrui; Gao, Wei; Shen, Junsong; Chen, Yingjie; Liu, Xiang; Wang, Yumin; Gong, Xianzu; Hu, Liqun; Chen, Junlin; Zhang, Xiaodong; Wan, Baonian; Li, Jiangang; Morita, Shigeru; Ohishi, Tetsutarou; Goto, Motoshi; Dong, Chunfeng; and others

    2015-12-15

    A flat-field extreme ultraviolet (EUV) spectrometer working in the 20-500 Å wavelength range with fast time response has been newly developed to measure line emissions from highly ionized tungsten in the Experimental Advanced Superconducting Tokamak (EAST) with a tungsten divertor, while the monitoring of light and medium impurities is also an aim in the present development. A flat-field focal plane for spectral image detection is made by a laminar-type varied-line-spacing concave holographic grating with an angle of incidence of 87°. A back-illuminated charge-coupled device (CCD) with a total size of 26.6 × 6.6 mm{sup 2} and pixel numbers of 1024 × 255 (26 × 26 μm{sup 2}/pixel) is used for recording the focal image of spectral lines. An excellent spectral resolution of Δλ{sub 0} = 3-4 pixels, where Δλ{sub 0} is defined as full width at the foot position of a spectral line, is obtained at the 80-400 Å wavelength range after careful adjustment of the grating and CCD positions. The high signal readout rate of the CCD can improve the temporal resolution of time-resolved spectra when the CCD is operated in the full vertical binning mode. It is usually operated at 5 ms per frame. If the vertical size of the CCD is reduced with a narrow slit, the time response becomes faster. The high-time response in the spectral measurement therefore makes possible a variety of spectroscopic studies, e.g., impurity behavior in long pulse discharges with edge-localized mode bursts. An absolute intensity calibration of the EUV spectrometer is also carried out with a technique using the EUV bremsstrahlung continuum at 20-150 Å for quantitative data analysis. Thus, the high-time resolution tungsten spectra have been successfully observed with good spectral resolution using the present EUV spectrometer system. Typical tungsten spectra in the EUV wavelength range observed from EAST discharges are presented with absolute intensity and spectral identification.

  14. A fast-time-response extreme ultraviolet spectrometer for measurement of impurity line emissions in the Experimental Advanced Superconducting Tokamak

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; Morita, Shigeru; Xu, Zong; Wu, Zhenwei; Zhang, Pengfei; Wu, Chengrui; Gao, Wei; Ohishi, Tetsutarou; Goto, Motoshi; Shen, Junsong; Chen, Yingjie; Liu, Xiang; Wang, Yumin; Dong, Chunfeng; Zhang, Hongmin; Huang, Xianli; Gong, Xianzu; Hu, Liqun; Chen, Junlin; Zhang, Xiaodong; Wan, Baonian; Li, Jiangang

    2015-12-01

    A flat-field extreme ultraviolet (EUV) spectrometer working in the 20-500 Å wavelength range with fast time response has been newly developed to measure line emissions from highly ionized tungsten in the Experimental Advanced Superconducting Tokamak (EAST) with a tungsten divertor, while the monitoring of light and medium impurities is also an aim in the present development. A flat-field focal plane for spectral image detection is made by a laminar-type varied-line-spacing concave holographic grating with an angle of incidence of 87°. A back-illuminated charge-coupled device (CCD) with a total size of 26.6 × 6.6 mm2 and pixel numbers of 1024 × 255 (26 × 26 μm2/pixel) is used for recording the focal image of spectral lines. An excellent spectral resolution of Δλ0 = 3-4 pixels, where Δλ0 is defined as full width at the foot position of a spectral line, is obtained at the 80-400 Å wavelength range after careful adjustment of the grating and CCD positions. The high signal readout rate of the CCD can improve the temporal resolution of time-resolved spectra when the CCD is operated in the full vertical binning mode. It is usually operated at 5 ms per frame. If the vertical size of the CCD is reduced with a narrow slit, the time response becomes faster. The high-time response in the spectral measurement therefore makes possible a variety of spectroscopic studies, e.g., impurity behavior in long pulse discharges with edge-localized mode bursts. An absolute intensity calibration of the EUV spectrometer is also carried out with a technique using the EUV bremsstrahlung continuum at 20-150 Å for quantitative data analysis. Thus, the high-time resolution tungsten spectra have been successfully observed with good spectral resolution using the present EUV spectrometer system. Typical tungsten spectra in the EUV wavelength range observed from EAST discharges are presented with absolute intensity and spectral identification.

  15. Antibacterial effects on dry-fast and traditional water-based surgical scrubbing methods: a two-time points experimental study.

    PubMed

    Chen, Shu-Hwa; Chou, Chuan-Yu; Huang, Jui-Chen; Tang, Ya-Fen; Kuo, Yur-Ren; Chien, Li-Yu

    2014-06-01

    This study determined the in-use effects of dry-fast and traditional hand-washing surgical scrubs among operating room staff members. This is a static group comparison study with purposive sampling. A total of 156 staff members were recruited in an operating room in a medical center located in southern Taiwan. The participants were divided into traditional and dry-fast hand-washing groups. Microbial counts were measured right after the two groups finished surgical scrubbing and at the completion of surgery. The results showed that the use of dry-fast antisepsis has a better persistent effect (P = 0.001), more nurses chose dry-fast antisepsis than surgeons (P = 0.012), and the post-operation number of colonies for nurses was significantly higher than that for surgeons (P = 0.003). Operating room nurses are long-term and frequent users of antibacterial agents, and their requirement of skin protection is higher. The dry-fast technique has the advantage of being less irritating to the skin and less time consuming; therefore, brush-free and dry-fast antisepsis is recommended. PMID:23992610

  16. Global sea level rise

    SciTech Connect

    Douglas, B.C. )

    1991-04-15

    Published values for the long-term, global mean sea level rise determined from tide gauge records exhibit considerable scatter, from about 1 mm to 3 mm/yr. This disparity is not attributable to instrument error; long-term trends computed at adjacent sites often agree to within a few tenths of a millimeter per year. Instead, the differing estimates of global sea level rise appear to be in large part due to authors' using data from gauges located at convergent tectonic plate boundaries, where changes of land elevation give fictitious sea level trends. In addition, virtually all gauges undergo subsidence or uplift due to postglacial rebound (PGR) from the last deglaciation at a rate comparable to or greater than the secular rise of sea level. Modeling PGR by the ICE-3G model of Tushingham and Peltier (1991) and avoiding tide gauge records in areas of converging tectonic plates produces a highly consistent set of long sea level records. The value for mean sea level rise obtained from a global set of 21 such stations in nine oceanic regions with an average record length of 76 years during the period 1880-1980 is 1.8 mm/yr {plus minus} 0.1. This result provides confidence that carefully selected long tide gauge records measure the same underlying trend of sea level and that many old tide gauge records are of very high quality.

  17. High speed electrostatic photomultiplier tube for the 1.06 micrometer wavelength. Cup and slat dynode chain combined with flat cathode and coax output produces 0.25 nsec rise time

    NASA Technical Reports Server (NTRS)

    Sparks, S. D.

    1973-01-01

    The Varian cup and slat dynode chain was modified to have a flat cathode. These modifications were incorporated in an all-electrostatic photomultiplier tube having a rise time of 0.25 n sec. The tube delivered under the contract had a flat S-20 opaque cathode with a useful diameter of 5 mm. The design of the tube is such that a III to V cathode support is mounted in place of the existing cathode substrate. This cathode support is designed to accept a transferred III to V cathode and maintain the cathode surface in the same position as the S-20 photocathode.

  18. Timing of herbage and fasting allocation in strip grazed cattle: Effects on patterns of ingestive behavior, herbage intake, and nutrient supply

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Afternoon herbage allocations have shown to improve animal performance due to an increment in herbage intake during dusk, when herbage quality is higher. However, this phenomenon might not yet be maximized. This work aimed to assess the impact of timing of herbage and fasting allocation on patterns ...

  19. A Search for Fast Radio Bursts at Low Frequencies with Murchison Widefield Array High Time Resolution Imaging

    NASA Astrophysics Data System (ADS)

    Tingay, S. J.; Trott, C. M.; Wayth, R. B.; Bernardi, G.; Bowman, J. D.; Briggs, F.; Cappallo, R. J.; Deshpande, A. A.; Feng, L.; Gaensler, B. M.; Greenhill, L. J.; Hancock, P. J.; Hazelton, B. J.; Johnston-Hollitt, M.; Kaplan, D. L.; Lonsdale, C. J.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Murphy, T.; Oberoi, D.; Prabu, T.; Udaya Shankar, N.; Srivani, K. S.; Subrahmanyan, R.; Webster, R. L.; Williams, A.; Williams, C. L.

    2015-12-01

    We present the results of a pilot study search for fast radio bursts (FRBs) using the Murchison Widefield Array (MWA) at low frequencies (139-170 MHz). We utilized MWA data obtained in a routine imaging mode from observations where the primary target was a field being studied for Epoch of Reionization detection. We formed images with 2 s time resolution and 1.28 MHz frequency resolution for 10.5 hr of observations, over 400 square degrees of the sky. We de-dispersed the dynamic spectrum in each of 372,100 resolution elements of 2 × 2 arcmin2, between dispersion measures of 170 and 675 pc cm-3. Based on the event rate calculations in Trott et al., which assume a standard candle luminosity of 8 × 1037 Js-1, we predict that with this choice of observational parameters, the MWA should detect (˜10, ˜2, ˜0) FRBs with spectral indices corresponding to (-2, -1, 0), based on a 7σ detection threshold. We find no FRB candidates above this threshold from our search, placing an event rate limit of \\lt 700 above 700 Jy ms per day per sky and providing evidence against spectral indices α \\lt -1.2 (S\\propto {ν }α ). We compare our event rate and spectral index limits with others from the literature. We briefly discuss these limits in light of recent suggestions that supergiant pulses from young neutron stars could explain FRBs. We find that such supergiant pulses would have to have much flatter spectra between 150 and 1400 MHz than have been observed from Crab giant pulses to be consistent with the FRB spectral index limit we derive.

  20. A FOCUSED TRANSPORT APPROACH TO THE TIME-DEPENDENT SHOCK ACCELERATION OF SOLAR ENERGETIC PARTICLES AT A FAST TRAVELING SHOCK

    SciTech Connect

    Le Roux, J. A.; Webb, G. M.

    2012-02-10

    Some of the most sophisticated models for solar energetic particle (SEP) acceleration at coronal mass ejection driven shocks are based on standard diffusive shock acceleration theory. However, this theory, which only applies when SEP pitch-angle anisotropies are small, might have difficulty in describing first-order Fermi acceleration or the shock pre-heating and injection of SEPs into first-order Fermi acceleration accurately at lower SEP speeds where SEP pitch-angle anisotropies upstream near the shock can be large. To avoid this problem, we use a time-dependent focused transport model to reinvestigate first-order Fermi acceleration at planar parallel and quasi-parallel spherical traveling shocks between the Sun and Earth with high shock speeds associated with rare extreme gradual SEP events. The focused transport model is also used to investigate and compare three different shock pre-heating mechanisms associated with different aspects of the nonuniform cross-shock solar wind flow, namely, the convergence of the flow (adiabatic compression), the shear tensor of the flow, and the acceleration of the flow, and a fourth shock pre-heating mechanism associated with the cross-shock electric field, to determine which pre-heating mechanism contributes the most to injecting shock pre-heated source particles into the first-order Fermi acceleration process. The effects of variations in traveling shock conditions, such as increasing shock obliquity and shock slowdown, and variations in the SEP source with increasing shock distance from the Sun on the coupled processes of shock pre-heating, injection, and first-order Fermi acceleration are analyzed. Besides the finding that the cross-shock acceleration of the solar wind flow yields the dominant shock pre-heating mechanism at high shock speeds, we find that first-order Fermi acceleration at fast traveling shocks differs in a number of respects from the predictions and assumptions of standard steady-state diffusive shock

  1. Unsaturated-zone fast-path flow calculations for Yucca Mountain groundwater travel time analyses (GWTT-94)

    SciTech Connect

    Arnold, B.W.; Altman, S.J.; Robey, T.H.

    1995-08-01

    Evaluation of groundwater travel time (GWTT) is required as part of the investigation of the suitability of Yucca Mountain as a potential high-level nuclear-waste repository site. The Nuclear Regulatory Commission`s GWTT regulation is considered to be a measure of the intrinsic ability of the site to contain radionuclide releases from the repository. The work reported here is the first step in a program to provide an estimate of GWTT at the Yucca Mountain site in support of the DOE`s Technical Site Suitability and as a component of a license application. Preliminary estimation of the GWTT distribution in the unsaturated zone was accomplished using a numerical model of the physical processes of groundwater flow in the fractured, porous medium of the bedrock. Based on prior investigations of groundwater flow at the site, fractures are thought to provide the fastest paths for groundwater flow; conditions that lead to flow in fractures were investigated and simulated. Uncertainty in the geologic interpretation of Yucca Mountain was incorporated through the use of geostatistical simulations, while variability of hydrogeologic parameters within each unit was accounted for by the random sampling of parameter probability density functions. The composite-porosity formulation of groundwater flow was employed to simulate flow in both the matrix and fracture domains. In this conceptualization, the occurrence of locally saturated conditions within the unsaturated zone is responsible for the initiation of fast-path flow through fractures. The results of the GWTT-94 study show that heterogeneity in the hydraulic properties of the model domain is an important factor in simulating local regions of high groundwater saturation. Capillary-pressure conditions at the surface boundary influence the extent of the local saturation simulated.

  2. Synopsis of a computer program designed to interface a personal computer with the fast data acquisition system of a time-of-flight mass spectrometer

    NASA Technical Reports Server (NTRS)

    Bechtel, R. D.; Mateos, M. A.; Lincoln, K. A.

    1988-01-01

    Briefly described are the essential features of a computer program designed to interface a personal computer with the fast, digital data acquisition system of a time-of-flight mass spectrometer. The instrumentation was developed to provide a time-resolved analysis of individual vapor pulses produced by the incidence of a pulsed laser beam on an ablative material. The high repetition rate spectrometer coupled to a fast transient recorder captures complete mass spectra every 20 to 35 microsecs, thereby providing the time resolution needed for the study of this sort of transient event. The program enables the computer to record the large amount of data generated by the system in short time intervals, and it provides the operator the immediate option of presenting the spectral data in several different formats. Furthermore, the system does this with a high degree of automation, including the tasks of mass labeling the spectra and logging pertinent instrumental parameters.

  3. A fast direct method for block triangular Toeplitz-like with tri-diagonal block systems from time-fractional partial differential equations

    NASA Astrophysics Data System (ADS)

    Ke, Rihuan; Ng, Michael K.; Sun, Hai-Wei

    2015-12-01

    In this paper, we study the block lower triangular Toeplitz-like with tri-diagonal blocks system which arises from the time-fractional partial differential equation. Existing fast numerical solver (e.g., fast approximate inversion method) cannot handle such linear system as the main diagonal blocks are different. The main contribution of this paper is to propose a fast direct method for solving this linear system, and to illustrate that the proposed method is much faster than the classical block forward substitution method for solving this linear system. Our idea is based on the divide-and-conquer strategy and together with the fast Fourier transforms for calculating Toeplitz matrix-vector multiplication. The complexity needs O (MNlog2 ⁡ M) arithmetic operations, where M is the number of blocks (the number of time steps) in the system and N is the size (number of spatial grid points) of each block. Numerical examples from the finite difference discretization of time-fractional partial differential equations are also given to demonstrate the efficiency of the proposed method.

  4. Identification of Human Adenovirus in Respiratory Samples with Luminex Respiratory Virus Panel Fast V2 Assay and Real-Time Polymerase Chain Reaction.

    PubMed

    Esposito, Susanna; Scala, Alessia; Bianchini, Sonia; Zampiero, Alberto; Fossali, Emilio; Principi, Nicola

    2016-01-01

    In order to compare the last version of the Respiratory Virus Panel (RVP) Fast assay for human Adenovirus (hAdv) detection with a specific real-time polymerase chain reaction (qPCR), which is considered the gold standard for hAdv detection, nasopharyngeal samples collected from 309 children (age range, four months to eight years) with respiratory tract infection were tested using the RVP Fast v2 assay (Luminex Molecular Diagnostics, Inc., Toronto, ON, Canada) and a specific TaqMan qPCR to identify hAdv DNA. The RVP Fast v2 assay detected 30/61 (49.2%) hAdv infections that had been identified by real-time qPCR, demonstrating a significantly lower detection rate (p < 0.001). The sensitivity of the RVP Fast v2 assay in comparison to qPCR was lower in younger children (42.9% vs. 57.7%; Cohen's kappa coefficient, 0.53); in samples with co-infections (40.0% vs. 56.7%; Cohen's kappa coefficient, 0.52); and in samples with hAdv type C (45.9% vs. 57.1%; Cohen's kappa coefficient, 0.60). Samples with lower viral loads were associated with a significantly lower sensitivity of the RVP Fast v2 assay (35.1% vs. 68.2%, p = 0.01; Cohen's kappa coefficients, 0.49). The RVP Fast v2 assay has important limitations for the detection of hAdv and cannot be used to evaluate whether hAdvs are the main etiologic agent responsible for an outbreak or when epidemiological studies are performed. PMID:26927078

  5. Simple approximations for estimating quickly the motion and timing of salt diapir rise, overhang development, and associated thermal anomalies using present-day observations: Case history from the Gulf of Mexico and Danish North Sea

    SciTech Connect

    Lerche, I. ); Thomsen, R.O. )

    1993-09-01

    Estimates of the upward motion of salt, due solely to buoyancy forces, through deposited and depositing sedimentary cover can be split into several parts: the critical thickness of sedimentary cover necessary to cause an underlying salt to become buoyant; the critical thickness of sedimentary cover necessary for a salt diapir to reach the sediment mudline in the absence of an impeding pressure of competent sediments opposing salt rise and in the absence of significant overpressure (both differential impedance and differential overpressure will slow the rise of the salt to the mudline); the effective speed of motion of the salt through the nonimpeding sediments during the salt's buoyant-ascent phase; current observed salt-top depth below mudline versus nonimpeded predicted salt-top depth leading to (a) minimum estimate of mechanical strength of competent resistive layers, and (b) an approximate estimate of buoyancy pressure of salt attempting to penetrate the resistive cover layer; uplift estimate of the overlying competent sediments because of the buoyancy pressure, in relation to observed uplift, leading to an estimate of salt-diapir rise speed since reaching the impeding formation; timing estimates of [open quotes]mushroom cap[close quotes] development of salt since emplacement of the resistive overlying layer and an estimate of the lateral competence of sedimentary beds ahead of the mushroom-salt sheet cap as a consequence of the observed mushroom extent; an estimate of evolving thermal anomalies around the dynamic salt/sediment system as a consequence of high-salt thermal conductivity. Such simple rough estimation methods are important in assessing the local and regional factors influencing the dynamic, thermal, and hydrocarbon retention factors in basinal sediments influenced by salt. Examples from the Gulf of Mexico and the Danish North Sea illustrate how to use both seismic and/or downhole data to perform the simple estimates.

  6. "Eating Beans ... that Is a "No-No" for Our Times": Young Cypriots' Consumer Meanings of "Healthy" and "Fast" Food

    ERIC Educational Resources Information Center

    Ioannou, Soula

    2009-01-01

    Objective: To investigate in-depth beliefs and experiences relating to the choice of fast and/or healthy foods from a group of young people living in Cyprus. Design: Data for the study were generated from one-to-one qualitative interviews which encouraged the participants to articulate the symbolic value of eating choices in their day-to-day…

  7. Sea Level Rise in Tuvalu

    NASA Astrophysics Data System (ADS)

    Lin, C. C.; Ho, C. R.; Cheng, Y. H.

    2012-04-01

    Most people, especially for Pacific Islanders, are aware of the sea level change which may caused by many factors, but no of them has deeper sensation of flooding than Tuvaluan. Tuvalu, a coral country, consists of nine low-lying islands in the central Pacific between the latitudes of 5 and 10 degrees south, has the average elevation of 2 meters (South Pacific Sea Level and Climate Monitoring Project, SPSLCMP report, 2006) up to sea level. Meanwhile, the maximum sea level recorded was 3.44m on February 28th 2006 that damaged Tuvaluan's property badly. Local people called the flooding water oozes up out of the ground "King Tide", that happened almost once or twice a year, which destroyed the plant, polluted their fresh water, and forced them to colonize to some other countries. The predictable but uncontrollable king tide had been observed for a long time by SPSLCMP, but some of the uncertainties which intensify the sea level rise need to be analyzed furthermore. In this study, a span of 18 years of tide gauge data accessed from Sea Level Fine Resolution Acoustic Measuring Equipment (SEAFRAME) are compared with the satellite altimeter data accessed from Archiving Validation and Interpretation of Satellite Data in Oceanography (AVISO). All above are processed under the limitation of same time and spatial range. The outcome revealed a 9.26cm difference between both. After the tide gauge data shifted to the same base as altimeter data, the results showed the unknown residuals are always positive under the circumstances of the sea level rise above 3.2m. Apart from uncertainties in observing, the residual reflected unknown contributions. Among the total case number of sea level rise above 3.2m is 23 times, 22 of which were recorded with oceanic warm eddy happened simultaneously. The unknown residual seems precisely matched with oceanic warm eddies and illustrates a clear future approach for Tuvaluan to care for.

  8. Rising beyond elastocapillarity.

    PubMed

    Holmes, Douglas P; Brun, P-T; Pandey, Anupam; Protière, Suzie

    2016-06-14

    We consider the elastocapillary rise between swellable structures using a favorable solvent. We characterize the dynamic deformations and resulting equilibrium configurations for various beams. Our analysis reveals the importance of the spacing between the two beams, and the elastocapillary length lec, which prescribes the relative magnitude of surface tension and bending stiffness in the system. In particular, we rationalize the transition between coalescence-dominated, bending-dominated, and swelling-dominated regimes, and enumerate the subtle interfacial mechanisms at play in the ratcheting of a fluid droplet trapped between the curling beams. PMID:27076278

  9. Comparison of fast electric field changes from subsequent return strokes of natural and triggered lightning

    NASA Technical Reports Server (NTRS)

    Le Vine, D. M.; Willett, J.

    1988-01-01

    Fast electric field changes from subsequent return strokes of natural and triggered lightning with propagation paths almost entirely over water are compared. Data were collected at the Kennedy Space Center, Florida. Comparisons have been made of the average shape, the rise time and the spectrum of the electric field changes. The electric field changes from the triggered flashes tend to rise to peak faster and decay faster than do their counterparts in natural cloud-to-ground flashes.

  10. Reduced γ-γ time walk to below 50 ps using the multiplexed-start and multiplexed-stop fast-timing technique with LaBr3(Ce) detectors

    NASA Astrophysics Data System (ADS)

    Régis, J.-M.; Saed-Samii, N.; Rudigier, M.; Ansari, S.; Dannhoff, M.; Esmaylzadeh, A.; Fransen, C.; Gerst, R.-B.; Jolie, J.; Karayonchev, V.; Müller-Gatermann, C.; Stegemann, S.

    2016-07-01

    The electronic γ-γ fast-timing technique using arrays consisting of many LaBr3(Ce) detectors is a powerful method to determine lifetimes of nuclear excited states with a lower limit of about 5 ps. This method requires the determination of the energy-dependent time walk of the zero time which is represented by the centroid of a prompt γ-γ time distribution. The full-energy peak versus full-energy peak prompt response difference which represents the linearly combined mean γ-γ time walk of a fast-timing array consisting of 8 LaBr3(Ce) detectors was measured using a standard 152Eu γ-ray source for the energy region of 40-1408 keV. The data were acquired using a "multiplexed-start and multiplexed-stop" analogue electronics circuitry and analysed by employing the generalized centroid difference method. Concerning the cylindrical 1.5 in.×1.5 in. LaBr3(Ce) crystals which are coupled to the Hamamatsu R9779 photomultiplier tubes, the best fast-timing array time resolution of 202(3) ps is obtained for the two prompt γ lines of 60Co by using the leading-edge timing principle. When using the zero-crossover timing principle the time resolution is degraded by up to 30%, dependent on the energy and the shaping delay time of the constant fraction discriminator model Ortec 935. The smallest γ-γ time walk to below 50 ps is obtained by using a shaping delay time of about 17 ns and an optimum "time-walk adjustment" needed for detector output pulses with amplitudes smaller than 400 mV.

  11. Nothing But MORB at Shatsky Rise

    NASA Astrophysics Data System (ADS)

    Natland, J. H.

    2013-12-01

    were similar; conditions of differentiation in the shallow crust were similar; and the types of magma mixing were similar. This is the principal petrologic outcome of drilling at Shatsky Rise. Since magnetic anomalies across Shatsky Rise indicate that it formed along a migrating triple junction at a fast spreading ridge, the reason for its unusually thick and shallow crust remains speculative, except that it cannot have been produced at the head of a deeply sourced hot mantle plume. The migrating triple junction may simply have encountered a shallow welt in the depleted mantle, or pushed it ahead of itself, and then overran it, to produce the unusual volume of depleted basalt. Sano, T., et al (2012) G-Cubed doi:10.1029/2012GC004235 Gale, A., et al (2013) G-Cubed doi:10.1029/2012GC004334

  12. Understanding Sea-Level Rise and Variability

    NASA Astrophysics Data System (ADS)

    Anderson, John

    2011-05-01

    The debate about climate change lingers, fueled by the complexity of weather patterns around the Earth. The oceans filter spatial and temporal changes in temperature, yielding an undisputable record of warming and expansion that manifests as accelerated sea level rise. The rate of rise in historical time is nearly 6 times the average rate for the past 4000 years. Documentation of this accelerated rise, discussion of its causes and impacts, and descriptions of the methods used to measure sea level rise are provided in this compilation of 12 papers authored by some of the leading experts in the field. The book reads more like a textbook than an edited volume, a strategy seldom achieved in edited volumes.

  13. Four-dimensional visualization of rising microbubbles

    NASA Astrophysics Data System (ADS)

    Jung, Ji Won; Jeon, Hyung Min; Pyo, Jaeyeon; Lim, Jae-Hong; Weon, Byung Mook; Kohmura, Yoshiki; Ishikawa, Tetsuya; Je, Jung Ho

    2014-05-01

    Four-dimensional imaging, which indicates imaging in three spatial dimensions as a function of time, provides useful evidence to investigate the interactions of rising bubbles. However, this has been largely unexplored for microbubbles, mostly due to problems associated with strong light scattering and shallow depth of field in optical imaging. Here, tracking x-ray microtomography is used to visualize rising microbubbles in four dimensions. Bubbles are tracked by moving the cell to account for their rise velocity. The sizes, shapes, time-dependent positions, and velocities of individual rising microbubbles are clearly identified, despite substantial overlaps between bubbles in the field of view. Our tracking x-ray microtomography affords opportunities for understanding bubble-bubble (or particle) interactions at microscales - important in various fields such as microfluidics, biomechanics, and floatation.

  14. Four-dimensional visualization of rising microbubbles

    NASA Astrophysics Data System (ADS)

    Je, Jung Ho; Jung, Ji Won; Pyo, Jaeyeon; Lim, Jae-Hong

    2014-11-01

    Four-dimensional imaging, which indicates imaging in three spatial dimensions as a function of time, provides useful evidence to investigate the interactions of rising bubbles. However, this has been largely unexplored for microbubbles, mostly due to problems associated with strong light scattering and shallow depth of field in optical imaging. Here, we developed tracking x-ray microtomography that is capable of visualizing rising microbubbles in four dimensions. Bubbles are tracked by moving the in-situ cell to account for their rise velocity. The sizes, shapes, time-dependent positions, and velocities of individual rising microbubbles are clearly identified, despite substantial overlaps between bubbles in the field of view. Our tracking x-ray microtomography affords opportunities for understanding bubble-bubble (or particle) interactions at microscales - important in various fields such as microfluidics, biomechanics, and floatation.

  15. Structure of A Equals 76 Nuclei and Fast-Timing Studies of the Rare-Earth Region

    NASA Astrophysics Data System (ADS)

    Cooper, Nathan Michael

    produce useful results. Such cases include estimation of total -gamma-decay widths of neutron resonances and -gamma-ray spectra following nuclear reactions. Of particular interest in modern research are so-called pygmy resonances which may be due, for example, to a neutron skin resonance or other exotic modes of excitation. Another topic of continued interest is that of double-beta decay and in particular the search for neutrinoless double-beta (0vbeta) decay. Conclusive observation of 0 vbeta decay would show that the neutrino is its own anti-particle, and evaluation of the neutrino mass could be performed if the matrix element of the decay were known. Constraining parameters of theoretical models using experimental data is of the utmost importance to these calculations. In this dissertation, the structure of A = 76 nuclei near stability, candidates for involvement in the hypothetical 0vbeta decay of 76Ge, is explored though seven experiments performed at the Darmstadt High-Intensity Photon Source, the High Intensity Gamma-Ray Source, and at the Wright Nuclear Structure Laboratory. Of particular concern is the analysis and interpretation of nuclear resonance fluorescence data on 76Se, 76Ge, and nuclei in general. Details and results of experiments performed using fast-timing electronics to study structure of low-lying states of 174W and 176Hf at WNSL are additionally presented as an appendix.

  16. Fast Direct Injection Mass-Spectrometric Characterization of Stimuli for Insect Electrophysiology by Proton Transfer Reaction-Time of Flight Mass-Spectrometry (PTR-ToF-MS)

    PubMed Central

    Tasin, Marco; Cappellin, Luca; Biasioli, Franco

    2012-01-01

    Electrophysiological techniques are used in insect neuroscience to measure the response of olfactory neurons to volatile odour stimuli. Widely used systems to deliver an olfactory stimulus to a test insect include airstream guided flow through glass cartridges loaded with a given volatile compound on a sorbent support. Precise measurement of the quantity of compound reaching the sensory organ of the test organism is an urgent task in insect electrophysiology. In this study we evaluated the performances of the recent realised proton transfer reaction-time of flight mass-spectrometry (PTR-ToF-MS) as a fast and selective gas sensor. In particular, we characterised the gas emission from cartridges loaded with a set of volatile compounds belonging to different chemical classes and commonly used in electrophysiological experiments. PTR-ToF-MS allowed a fast monitoring of all investigated compounds with sufficient sensitivity and time resolution. The detection and the quantification of air contaminants and solvent or synthetic standards impurities allowed a precise quantification of the stimulus exiting the cartridge. The outcome of this study was twofold: on one hand we showed that PTR-ToF-MS allows monitoring fast processes with high sensitivity by real time detection of a broad number of compounds; on the other hand we provided a tool to solve an important issue in insect electrophysiology. PMID:22666020

  17. Was the economic crisis 1997-1998 responsible for rising suicide rates in East/Southeast Asia? A time-trend analysis for Japan, Hong Kong, South Korea, Taiwan, Singapore and Thailand.

    PubMed

    Chang, Shu-Sen; Gunnell, David; Sterne, Jonathan A C; Lu, Tsung-Hsueh; Cheng, Andrew T A

    2009-04-01

    In 1997-1998 a widespread economic crisis hit the economies of many East/Southeast Asian countries; its impact on suicide rates across the region has not been systematically documented. We investigated the impact of the Asian economic crisis (1997-1998) on suicide in Japan, Hong Kong, South Korea, Taiwan, Singapore and Thailand. Suicide and population data for the period 1985-2006 were extracted from the World Health Organisation's mortality database and Taiwanese mortality statistics. Sex-specific age-standardised suicide rates for people aged 15years or above were analysed using joinpoint regression. Trends in divorce, marriage, unemployment, gross domestic product (GDP) per capita and alcohol consumption were compared with trends in suicide rates graphically and using time-series analysis. Suicide mortality decreased in the late 1980s and early 1990s but subsequently increased markedly in all countries except Singapore, which had steadily declining suicide rates throughout the study period. Compared to 1997, male rates in 1998 rose by 39% in Japan, 44% in Hong Kong and 45% in Korea; rises in female rates were less marked. Male rates also rose in Thailand, but accurate data were incomplete. The economic crisis was associated with 10,400 more suicides in 1998 compared to 1997 in Japan, Hong Kong and Korea. Similar increases in suicide rates were not seen in Taiwan and Singapore, the two countries where the economic crisis had a smaller impact on GDP and unemployment. Time-series analyses indicated that some of the crisis's impact on male suicides was attributable to increases in unemployment. These findings suggest an association of the Asian economic crisis with a sharp increase in suicide mortality in some, but not all, East/Southeast Asian countries, and that these increases were most closely associated with rises in unemployment. PMID:19200631

  18. The formation of ice rises, their dynamics and role in the deglaciation of the Antarctic ice sheet

    NASA Astrophysics Data System (ADS)

    Favier, Lionel; Pattyn, Frank

    2015-04-01

    Numerous underwater mountains emerge from the edge of the continental shelf around the Antarctic ice sheet. During the last deglaciation, those features gave birth to ice rises, each being small scale copies of a continental ice sheet characterised by an ice divide and a local flow going outwards embedded within the fringing ice shelves. The well-known millenium-scale stability of ice rises can be strong indicators for the past deglaciation termination. However, the interpretation of physical measurements of an ice rise is not straightforward due to unknown past ice dynamics. Here, using the Bisicles ice-sheet model, we investigate for the first time the formation of an ice rise on top of an underwater mountain during the retreat of an ideal Antarctic-like ice sheet (i.e., including both grounded and floating ice flow). Prior to the retreat, the underwater mountain is barely detectable from the ice surface geometry and velocity. During the ice sheet retreat, induced by an increase of the sea level, an ice divide develops quickly above the underwater mountain. Within a short period of hundreds of years, the ice rise adopts a thousand years stability along with two main features: (i) a shifted upstream position of the ice rise compared to the mountain underneath and (ii) a geometrical asymmetry of the ice rise showing a gentle slope upstream and a steep slope downstream. We also investigate the influence of a non uniform surface mass balance on the migration of the ice divide. Our results provide additional ice dynamical constraints to facilitate numerical reconstructions of the last deglacial history in Antarctica as we demonstrate that ice rises are stable, but transient features of the ice shelf, stabilizing fast outlet flow. The timing of pinning and unpinning therefore becomes crucial in simulating the episodes of slow and fast grounding line retreat, respectively.

  19. Ground potential rise monitor

    DOEpatents

    Allen, Zachery Warren; Zevenbergen, Gary Allen

    2012-07-17

    A device and method for detecting ground potential rise (GPR) comprising a first electrode, a second electrode, and a voltage attenuator. The first electrode and the second electrode are both electrically connected to the voltage attenuator. A means for determining the presence of a dangerous ground potential is connected to the voltage attenuator. The device and method further comprises a means for enabling one or more alarms upon the detection of the dangerous ground potential. Preferably, a first transmitter/receiver is connected to the means for enabling one or more alarms. Preferably, a second transmitter/receiver, comprising a button, is electromagnetically connected to the first transmitter/receiver. Preferably, the means for determining the presence of a dangerous ground potential comprises a means for determining the true RMS voltage at the output of the voltage attenuator, a transient detector connected to the output of the voltage attenuator, or a combination thereof.

  20. Design concepts for a pulse power test facility to simulate EMP surges in overhead power lines. Part I. Fast pulse

    SciTech Connect

    Ramrus, A.

    1986-02-01

    Objective of the study was to create conceptual designs of high voltage pulsers capable of simulating two types of electromagnetic pulses (EMPs) caused by a high-altitude nuclear burst; the slow rise time magnetohydrodynamic (MHD-EMP) and the fast rise time high-altitude EMP (HEMP). The pulser design was directed towards facilities capable of performing EMP vulnerability testing of components used in the national electric power system.

  1. Real-time monitoring of electrically evoked catecholamine signals in the songbird striatum using in vivo fast-scan cyclic voltammetry

    PubMed Central

    Smith, Amanda R.; Garris, Paul A.; Casto, Joseph M.

    2015-01-01

    Fast-scan cyclic voltammetry is a powerful technique for monitoring rapid changes in extracellular neurotransmitter levels in the brain. In vivo fast-scan cyclic voltammetry has been used extensively in mammalian models to characterize dopamine signals in both anesthetized and awake preparations, but has yet to be applied to a non-mammalian vertebrate. The goal of this study was to establish in vivo fast-scan cyclic voltammetry in a songbird, the European starling, to facilitate real-time measurements of extracellular catecholamine levels in the avian striatum. In urethane-anesthetized starlings, changes in catecholamine levels were evoked by electrical stimulation of the ventral tegmental area and measured at carbon-fiber microelectrodes positioned in the medial and lateral striata. Catecholamines were elicited by different stimulations, including trains related to phasic dopamine signaling in the rat, and were analyzed to quantify presynaptic mechanisms governing exocytotic release and neuronal uptake. Evoked extracellular catecholamine dynamics, maximal amplitude of the evoked catecholamine signal, and parameters for catecholamine release and uptake did not differ between striatal regions and were similar to those determined for dopamine in the rat dorsomedial striatum under similar conditions. Chemical identification of measured catecholamine by its voltammogram was consistent with the presence of both dopamine and norepinephrine in striatal tissue content. However, the high ratio of dopamine to norepinephrine in tissue content and the greater sensitivity of the carbon-fiber microelectrode to dopamine compared to norepinephrine favored the measurement of dopamine. Thus, converging evidence suggests that dopamine was the predominate analyte of the electrically evoked catecholamine signal measured in the striatum by fast-scan cyclic voltammetry. Overall, comparisons between the characteristics of these evoked signals suggested a similar presynaptic regulation of

  2. Real-time monitoring of electrically evoked catecholamine signals in the songbird striatum using in vivo fast-scan cyclic voltammetry.

    PubMed

    Smith, Amanda R; Garris, Paul A; Casto, Joseph M

    2015-01-01

    Fast-scan cyclic voltammetry is a powerful technique for monitoring rapid changes in extracellular neurotransmitter levels in the brain. In vivo fast-scan cyclic voltammetry has been used extensively in mammalian models to characterize dopamine signals in both anesthetized and awake preparations, but has yet to be applied to a non-mammalian vertebrate. The goal of this study was to establish in vivo fast-scan cyclic voltammetry in a songbird, the European starling, to facilitate real-time measurements of extracellular catecholamine levels in the avian striatum. In urethane-anesthetized starlings, changes in catecholamine levels were evoked by electrical stimulation of the ventral tegmental area and measured at carbon-fiber microelectrodes positioned in the medial and lateral striata. Catecholamines were elicited by different stimulations, including trains related to phasic dopamine signaling in the rat, and were analyzed to quantify presynaptic mechanisms governing exocytotic release and neuronal uptake. Evoked extracellular catecholamine dynamics, maximal amplitude of the evoked catecholamine signal, and parameters for catecholamine release and uptake did not differ between striatal regions and were similar to those determined for dopamine in the rat dorsomedial striatum under similar conditions. Chemical identification of measured catecholamine by its voltammogram was consistent with the presence of both dopamine and norepinephrine in striatal tissue content. However, the high ratio of dopamine to norepinephrine in tissue content and the greater sensitivity of the carbon-fiber microelectrode to dopamine compared to norepinephrine favored the measurement of dopamine. Thus, converging evidence suggests that dopamine was the predominate analyte of the electrically evoked catecholamine signal measured in the striatum by fast-scan cyclic voltammetry. Overall, comparisons between the characteristics of these evoked signals suggested a similar presynaptic regulation of

  3. Development and demonstration of table-top synchronized fast-scan femtosecond time-resolved spectroscopy system by single-shot scan photo detector array

    NASA Astrophysics Data System (ADS)

    Yabushita, Atsushi; Kao, Chih-Hsien; Lee, Yu-Hsien; Kobayashi, Takayoshi

    2015-07-01

    Ultrafast dynamics is generally studied by pump-probe method with laser pulse, which scans optical delay by motorized stage step by step. Using ultrashort laser pulse shorter than typical molecular vibration periods, the pump-probe measurement can study both of electronic dynamics and vibration dynamics simultaneously. The probe wavelength dependence of the ultrafast electronic and vibration dynamics (UEVD) helps us to distinguish the signal contributions from the dynamics of the electronic ground state and that of the electronic excited states, which elucidates primary reaction mechanism after photoexcitation. Meanwhile, the measurement time of UEVD spectroscopy takes too long time to be used in realistic application. In our previous work, we have developed multi-channel lock-in amplifying (MLA) detectors to study UEVD at all probe wavelengths simultaneously, and synchronized it with laser and fast-scan delay stage to scan the data in five seconds. It enabled us to study UEVD spectroscopy even for photo-fragile materials. However, the home-made MLA detectors required for the measurement is expensive and massive in size and weight, thus not suitable for general researchers in the field of ultrafast time-resolved spectroscopy. In the present work, we have developed a table-top synchronized fast-scan femtosecond time-resolved spectroscopy system using single shot scan line CCD. This system measures time-resolved trace at all probe wavelengths simultaneously in five seconds. The CCD-based fast-scan time-resolved spectroscopy system enables us to study ultrafast dynamics of various materials even biomaterials, which have been thought to be hard or even impossible to be studied in previous methods.

  4. Fusion of time-dependent gamma production spectra from thermal neutron capture and fast neutron inelastic scattering to improve material detection

    NASA Astrophysics Data System (ADS)

    Gozani, T.; Elsalim, M.; Strellis, D.; Brown, D.

    2003-06-01

    Neutron-based inspection techniques are unique in their ability to provide material specific signatures, thus offering very high performance and automatic detection of explosives and other contraband. Thermal neutron capture gamma spectroscopy provides excellent sensitivities to hydrogen, nitrogen, chlorine, and other elements, which are characteristic to most explosives, drugs and other contraband that may be smuggled into the country. Fast neutron gamma production (mostly through inelastic scattering) provides good sensitivity to carbon and oxygen. When necessary, these two types of complementary interactions can be combined to yield a more accurate material determination inside small to medium size containers. Standard pulsed 14 MeV electronic neutron generators offer an efficient way to obtain these two types of interactions. Fast (14 MeV) neutrons are produced during the pulse. After the pulse, only the decaying thermal neutron population exists, and thus pure neutron capture gamma-rays are produced. Unfortunately, during the pulse (which is normally much longer than the neutron thermalization time) the fast neutron interactions are highly "contaminated" by the interactions of thermal neutrons within the object and the nearby gamma-ray detectors. This creates high background and spectral interferences in the common medium resolution detectors, such as NaI, BGO, etc. The use of an appropriate shielding, neutron spectrum tailoring, full spectral feature analysis as well as temporal information ("die-away" time) resulted in significant performance enhancements in detection of explosives, drugs and other contraband in difficult geometries.

  5. The Rise and Fall of Type Ia Supernova Light Curves in the SDSS-II Supernova Survey

    SciTech Connect

    Hayden, Brian T.; Garnavich, Peter M.; Kessler, Richard; Frieman, Joshua A.; Jha, Saurabh W.; Bassett, Bruce; Cinabro, David; Dilday, Benjamin; Kasen, Daniel; Marriner, John; Nichol, Robert C.; /Portsmouth U., ICG /Baltimore, Space Telescope Sci. /Johns Hopkins U.

    2010-01-01

    We analyze the rise and fall times of Type Ia supernova (SN Ia) light curves discovered by the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. From a set of 391 light curves k-corrected to the rest-frame B and V bands, we find a smaller dispersion in the rising portion of the light curve compared to the decline. This is in qualitative agreement with computer models which predict that variations in radioactive nickel yield have less impact on the rise than on the spread of the decline rates. The differences we find in the rise and fall properties suggest that a single 'stretch' correction to the light curve phase does not properly model the range of SN Ia light curve shapes. We select a subset of 105 light curves well observed in both rise and fall portions of the light curves and develop a '2-stretch' fit algorithm which estimates the rise and fall times independently. We find the average time from explosion to B-band peak brightness is 17.38 {+-} 0.17 days, but with a spread of rise times which range from 13 days to 23 days. Our average rise time is shorter than the 19.5 days found in previous studies; this reflects both the different light curve template used and the application of the 2-stretch algorithm. The SDSS-II supernova set and the local SNe Ia with well-observed early light curves show no significant differences in their average rise-time properties. We find that slow-declining events tend to have fast rise times, but that the distribution of rise minus fall time is broad and single peaked. This distribution is in contrast to the bimodality in this parameter that was first suggested by Strovink (2007) from an analysis of a small set of local SNe Ia. We divide the SDSS-II sample in half based on the rise minus fall value, t{sub r} - t{sub f} {approx}< 2 days and t{sub r} - t{sub f} > 2 days, to search for differences in their host galaxy properties and Hubble residuals; we find no difference in host galaxy properties or Hubble residuals in our

  6. Time-resolved measurement of photon emission during fast crack propagation in three-point bending fracture of silica glass and soda lime glass

    SciTech Connect

    Shiota, Tadashi Sato, Yoshitaka; Yasuda, Kouichi

    2014-03-10

    Simultaneous time-resolved measurements of photon emission (PE) and fast crack propagation upon bending fracture were conducted in silica glass and soda lime glass. Observation of fracture surfaces revealed that macroscopic crack propagation behavior was similar between the silica glass and soda lime glass when fracture loads for these specimens were comparable and cracks propagated without branching. However, a large difference in the PE characteristics was found between the two glasses. In silica glass, PE (645–655 nm) was observed during the entire crack propagation process, whereas intense PE (430–490 nm and 500–600 nm) was observed during the initial stages of propagation. In contrast, only weak PE was detected in soda lime glass. These results show that there is a large difference in the atomic processes involved in fast crack propagation between these glasses, and that PE can be used to study brittle fracture on the atomic scale.

  7. Rapid sea-level rise

    NASA Astrophysics Data System (ADS)

    Cronin, Thomas M.

    2012-11-01

    Several global and regional factors contribute to observed sea-level change along any particular coast. Global processes include changes in ocean mass (glacio-eustasy from ice melt), ocean volume (steric effects), viscoelastic land movements (glacioisostatic adjustment GIA), and changes in terrestrial water storage. Regional processes, often connected to steric and glacial changes, include changes in ocean circulation (Meridional Overturning Circulation [MOC]), glacial melting, local GIA, regional subsidence and others. Paleoclimate, instrumental and modeling studies show that combinations of these factors can cause relatively rapid rates of sea-level rise exceeding 3 mm yr-1 over various timescales along particular coasts. This paper discusses patterns and causes of sea-level rise with emphasis on paleoclimatological records. It then addresses the hypothesis of late Holocene (pre-20th century) sea-level stability in light of paleoclimatic evidence, notably from reconstructions of sea-surface temperature and glacial activity, for significant climate and sea-level variability during this time. The practical difficulties of assessing regional sea-level (SL) patterns at submillennial timescales will be discussed using an example from the eastern United States.

  8. Breakdown in helium in high-voltage open discharge with subnanosecond current front rise

    NASA Astrophysics Data System (ADS)

    Schweigert, I. V.; Alexandrov, A. L.; Bokhan, P. A.; Zakrevskiy, Dm. E.

    2016-07-01

    Investigations of high-voltage open discharge in helium have shown a possibility of generation of current pulses with subnanosecond front rise, due to ultra-fast breakdown development. The open discharge is ignited between two planar cathodes with mesh anode in the middle between them. For gas pressure 6 Torr and 20 kV applied voltage, the rate of current rise reaches 500 A/(cm2 ns) for current density 200 A/cm2 and more. The time of breakdown development was measured for different helium pressures and a kinetic model of breakdown in open discharge is presented, based on elementary reactions for electrons, ions and fast atoms. The model also includes various cathode emission processes due to cathode bombardment by ions, fast atoms, electrons and photons of resonant radiation with Doppler shift of frequency. It is shown, that the dominating emission processes depend on the evolution of the discharge voltage during the breakdown. In the simulations, two cases of voltage behavior were considered: (i) the voltage is kept constant during the breakdown; (ii) the voltage is reduced with the growth of current. For the first case, the exponentially growing current is maintained due to photoemission by the resonant photons with Doppler-shifted frequency. For the second case, the dominating factor of current growth is the secondary electron emission. In both cases, the subnanosecond rise of discharge current was obtained. Also the effect of gas pressure on breakdown development was considered. It was found that for 20 Torr gas pressure the time of current rise decreases to 0.1 ns, which is in agreement with experimental data.

  9. Arrested Bubble Rise in a Narrow Tube

    NASA Astrophysics Data System (ADS)

    Lamstaes, Catherine; Eggers, Jens

    2016-06-01

    If a long air bubble is placed inside a vertical tube closed at the top it can rise by displacing the fluid above it. However, Bretherton found that if the tube radius, R, is smaller than a critical value Rc=0.918 ℓ_c , where ℓ_c=√{γ /ρ g} is the capillary length, there is no solution corresponding to steady rise. Experimentally, the bubble rise appears to have stopped altogether. Here we explain this observation by studying the unsteady bubble motion for Rrise in infinite time remains very small, giving the appearance of arrested motion.

  10. The rise of graphene

    NASA Astrophysics Data System (ADS)

    Geim, A. K.; Novoselov, K. S.

    2007-03-01

    Graphene is a rapidly rising star on the horizon of materials science and condensed-matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality, and, despite its short history, has already revealed a cornucopia of new physics and potential applications, which are briefly discussed here. Whereas one can be certain of the realness of applications only when commercial products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena, some of which are unobservable in high-energy physics, can now be mimicked and tested in table-top experiments. More generally, graphene represents a conceptually new class of materials that are only one atom thick, and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications.

  11. The rise of graphene.

    PubMed

    Geim, A K; Novoselov, K S

    2007-03-01

    Graphene is a rapidly rising star on the horizon of materials science and condensed-matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality, and, despite its short history, has already revealed a cornucopia of new physics and potential applications, which are briefly discussed here. Whereas one can be certain of the realness of applications only when commercial products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena, some of which are unobservable in high-energy physics, can now be mimicked and tested in table-top experiments. More generally, graphene represents a conceptually new class of materials that are only one atom thick, and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications. PMID:17330084

  12. Matched elastic constants for a perfect helical planar state and a fast switching time in chiral nematic liquid crystals.

    PubMed

    Yu, Meina; Zhou, Xiaochen; Jiang, Jinghua; Yang, Huai; Yang, Deng-Ke

    2016-05-11

    Chiral nematic liquid crystals possess a self-assembled helical structure and exhibit unique selective reflection in visible and infrared light regions. Their optical properties can be electrically tuned. The tuning involves the unwinding and restoring of the helical structure. We carried out an experimental study on the mechanism of the restoration of the helical structure. We constructed chiral nematic liquid crystals with variable elastic constants by doping bent-dimers and studied their impact on the restoration. With matched twist and bend elastic constants, the helical structure can be restored dramatically fast from the field-induced homeotropic state. Furthermore, defects can be eliminated to produce a perfect planar state which exhibits high selective reflection. PMID:27116620

  13. Energy- and time-resolved measurements of fast ions emitted from plasma-focus discharges by means of a Thomson spectrometer

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, R.; Czaus, K.; Paduch, M.; Sadowski, M. J.; Skladnik-Sadowska, E.; Zaloga, D. R.; Zielinska, E.; Żebrowski, J.

    2015-09-01

    The paper presents results of time-resolved measurements of fast deuterons emitted from high-current discharges of the Plasma-Focus (PF) type. The measurements were performed in a modified PF-1000U facility which is operated at the IFPiLM in Warsaw, Poland. The device was equipped with a fast-acting gas valve placed inside the inner electrode and oriented along the z-axis. The valve could inject a small volume of a chosen gas in front of this electrode. The PF discharges were initiated at the initial deuterium pressure equal to 1.6 or 2 hPa, with or without the use of the gas-puffing. Such discharges emitted intense beams of accelerated primary ions and X-ray pulses as well as products of nuclear fusion reactions. The reported measurements of the fast ion beams were performed by means of a Thomson-type spectrometer located at a chosen distance at the z-axis and equipped with miniature scintillation detectors. These detectors were placed in different points upon the deuteron parabola which corresponded to determined energy values. The detectors configuration allowed us to determine instants of the ion emission (using a TOF technique) and to compare them with instants of the X-ray emission. The collected data provided important information about emission characteristics of the modified PF-1000U facility.

  14. Capillary rise kinetics of some building materials.

    PubMed

    Karoglou, M; Moropoulou, A; Giakoumaki, A; Krokida, M K

    2005-04-01

    The presence of water in masonry is one of the main factors in deterioration. Capillary rise is the most usual mechanism of water penetration into building materials. In this study the kinetics of the capillary rise phenomenon was studied for various building materials: four stones, two bricks, and six plasters. A first-order kinetic model was proposed, in which the equilibrium moisture height derived from Darcy law. The capillary height time constant found to be strongly affected by the material characteristics. Moreover, the capillary height time constant can be predicted if the average pore radius of the materials is known. PMID:15752811

  15. A real-time framework for fast data retrieval in an image database of volcano activity scenarios

    NASA Astrophysics Data System (ADS)

    Aliotta, Marco Antonio; Cannata, Andrea; Cassisi, Carmelo; Ciancitto, Francesco; Montalto, Placido; Prestifilippo, Michele

    2015-04-01

    Explosive Activity at Stromboli Volcano (Aeolian Islands) is continuously monitored by INGV-OE in order to analyze its eruptive dynamics and specific scenarios. In particular, the images acquired from thermal cameras represent a big collection of data. In order to extract useful information from thermal image sequences, we need an efficient way to explore and retrieve information from a huge amount of data. In this work, a novel framework capable of fast data retrieval, using the "metric space" concept, is shown. In the light of it, we implemented an indexing algorithm related to similarity laws. The focal point is finding objects of a set that are "close" in relation to a given query, according to a similarity criterion. In order to perform this task, we performed morphological image processing techniques to each video frame, in order to map the shape area of each explosion into a closed curve, representing the explosion contour itself. In order to constitute a metric space, we chose a certain number of features obtained from parameters related to this closed curve and used them as objects of this metric space where similarity can be evaluated, using an appropriate "metric" function to calculate the distances. Unfortunately, this approach has to deal with an intrinsic issue involving the complexity and the number of distance functions to be calculated on a large amount of data. To overcome this drawback, we used a novel abstract data structure called "K-Pole Tree", having the property of minimizing the number of distances to be calculated among objects. Our method allows for fast retrieval of similar objects using an euclidean distance function among the features of the metric space. Thus, we can cluster explosions related to different kinds of volcanic activity, using "pivot" items. For example, given a known image sequence related to a particular type of explosion, it is possible to quickly and easily find all the image sequences that contain only similar

  16. Effects of hydraulic retention time on aerobic granulation and granule growth kinetics at steady state with a fast start-up strategy.

    PubMed

    Liu, Yong-Qiang; Zhang, Xing; Zhang, Rui; Liu, Wen-Tso; Tay, Joo-Hwa

    2016-01-01

    A hydraulic retention time (HRT) of 4, 6, and 8 h was employed, respectively, in three reactors to study the effects of HRT on granulation with a newly developed fast granulation strategy, i.e., a strategy by combining strong hydraulic selection pressure with high organic loading rate (OLR). Granules with clear boundary appeared within 24 h after reactor start-up and all reactors reached a pseudo steady state after 6-day operation. A 4-h HRT resulted in a relatively higher increasing rate in terms of granule size during granule development period, i.e., 208 μm day(-1), and the bigger granule size and the higher sludge volume index at the pseudo steady state. For HRT of 6 or 8 h, no obvious difference was observed. However, it was found that HRT influenced sludge retention time (SRT) and kinetics significantly. A HRT changing from 4 to 8 h led to an increased SRT from 3 to 21 days, a decreased observed specific biomass growth rate (μ obs) and an decreased observed biomass yield (Y obs) of stable granules from 0.37 to 0.062 days(-1), and 0.177 to 0.055 g MLVSS g(-1) COD, respectively. Both μ obs and Y obs had a linear relationship with the reciprocal of HRT. In addition, the great difference of microbial community between seed sludge, sludge retained in the reactors, and sludge washed out indicated a strong microbial selection for fast granulation within 24 h. However, during the granule development period from day 1 to 6, no more microbial selection was observed except an adjustment of microbial community. Little influence of HRT on microbial population in granular sludge indicated a minor role of HRT played for granulation with the fast start-up strategy adopted in this study. The results demonstrated that hydraulic selection pressure for granulation was mainly from short settling time, which led to strong microbial selection during the granulation period. Meanwhile, although HRT did not affect granulation with the fast start-up strategy, it played an

  17. Diagnosis of Cetacean morbillivirus: A sensitive one step real time RT fast-PCR method based on SYBR(®) Green.

    PubMed

    Sacristán, Carlos; Carballo, Matilde; Muñoz, María Jesús; Bellière, Edwige Nina; Neves, Elena; Nogal, Verónica; Esperón, Fernando

    2015-12-15

    Cetacean morbillivirus (CeMV) (family Paramyxoviridae, genus Morbillivirus) is considered the most pathogenic virus of cetaceans. It was first implicated in the bottlenose dolphin (Tursiops truncatus) mass stranding episode along the Northwestern Atlantic coast in the late 1980s, and in several more recent worldwide epizootics in different Odontoceti species. This study describes a new one step real-time reverse transcription fast polymerase chain reaction (real-time RT-fast PCR) method based on SYBR(®) Green to detect a fragment of the CeMV fusion protein gene. This primer set also works for conventional RT-PCR diagnosis. This method detected and identified all three well-characterized strains of CeMV: porpoise morbillivirus (PMV), dolphin morbillivirus (DMV) and pilot whale morbillivirus (PWMV). Relative sensitivity was measured by comparing the results obtained from 10-fold dilution series of PMV and DMV positive controls and a PWMV field sample, to those obtained by the previously described conventional phosphoprotein gene based RT-PCR method. Both the conventional and real-time RT-PCR methods involving the fusion protein gene were 100- to 1000-fold more sensitive than the previously described conventional RT-PCR method. PMID:26454114

  18. "Real-time" disintegration analysis and D-optimal experimental design for the optimization of diclofenac sodium fast-dissolving films.

    PubMed

    El-Malah, Yasser; Nazzal, Sami

    2013-01-01

    The objective of this work was to study the dissolution and mechanical properties of fast-dissolving films prepared from a tertiary mixture of pullulan, polyvinylpyrrolidone and hypromellose. Disintegration studies were performed in real-time by probe spectroscopy to detect the onset of film disintegration. Tensile strength and elastic modulus of the films were measured by texture analysis. Disintegration time of the films ranged from 21 to 105 seconds whereas their mechanical properties ranged from approximately 2 to 49 MPa for tensile strength and 1 to 21 MPa% for young's modulus. After generating polynomial models correlating the variables using a D-Optimal mixture design, an optimal formulation with desired responses was proposed by the statistical package. For validation, a new film formulation loaded with diclofenac sodium based on the optimized composition was prepared and tested for dissolution and tensile strength. Dissolution of the optimized film was found to commence almost immediately with 50% of the drug released within one minute. Tensile strength and young's modulus of the film were 11.21 MPa and 6, 78 MPa%, respectively. Real-time spectroscopy in conjunction with statistical design were shown to be very efficient for the optimization and development of non-conventional intraoral delivery system such as fast dissolving films. PMID:22780708

  19. 2-D time evolution of T/sub e/ during sawtooth crash based on fast ECE (electron cyclotron emission) measurements on TFTR

    SciTech Connect

    Kuo-Petravic, G.

    1988-12-01

    Electron cyclotron emission measurements taken at 20 locations in the horizontal midplane during a sawtooth crash have been analysed based on the assumption of fast rigid rotation of the plasma. Due to this fast rotation (approx.100..mu..sec), which remains fairly constant throughout the sawtooth crash, we have been able to make time-to-space reconstructions of half the poloidal plane using points which are separated in time by not more than 40..mu..sec. The existence of a temperature flattening in the precursor phase, which we interpret as an m = 1 temperature island, is clearly demonstrated, and its location and width agree well with local emissivity measurements from soft x-ray tomography viewing the same poloidal plane. The rotating temperature island in the precursor phase, the outward movement of the region of high T/sub c/ during the crash phase, and the shape of T/sub e/ during the crash phase, and the shape of T/sub e/ distribution after the crash during the successor phase have all been documented in a time sequence of color contours. 4 refs., 10 figs.

  20. Fast and Reliable Time Delay Estimation of Strong Lens Systems Using the Smoothing and Cross-correlation Methods

    NASA Astrophysics Data System (ADS)

    Aghamousa, Amir; Shafieloo, Arman

    2015-05-01

    The observable time delays between multiple images of strong lensing systems with time variable sources can provide us with some valuable information for probing the expansion history of the universe. Estimating these time delays can be very challenging due to complexities in the observed data caused by seasonal gaps, various noises, and systematics such as unknown microlensing effects. In this paper, we introduce a novel approach for estimating the time delays for strong lensing systems, implementing various statistical methods of data analysis including the smoothing and cross-correlation methods. The method we introduce in this paper has recently been used in the TDC0 and TDC1 Strong Lens Time Delay Challenges and has shown its power in providing reliable and precise estimates of time delays dealing with data with different complexities.