Science.gov

Sample records for rms time resolution

  1. A 16 channel high resolution (<11 ps RMS) Time-to-Digital Converter in a Field Programmable Gate Array

    NASA Astrophysics Data System (ADS)

    Ugur, C.; Bayer, E.; Kurz, N.; Traxler, M.

    2012-02-01

    A 16-channel Time-to-Digital Converter (TDC) was implemented in a general purpose Field-Programmable Gate Array (FPGA). The fine time calculations are achieved by using the dedicated carry-chain lines. The coarse counter defines the coarse time stamp. In order to overcome the negative effects of temperature and power supply dependency bin-by-bin calibration is applied. The time interval measurements are done using 2 channels. The time resolution of channels are calculated for 1 clock cycle and a minimum of 10.3 ps RMS on two channels, yielding 7.3 ps RMS (10.3 ps/√2) on a single channel is achieved.

  2. A 75 ps rms time resolution BiCMOS time to digital converter optimized for high rate imaging detectors

    NASA Astrophysics Data System (ADS)

    Hervé, C.; Torki, K.

    2002-04-01

    This paper presents an integrated time to digital converter (TDC) with a bin size adjustable in the range of 125 to 175 ps and a differential nonlinearity of ±0.3%. The TDC has four channels. Its architecture has been optimized for the readout of imaging detectors in use at Synchrotron Radiation facilities. In particular, a built-in logic flags piled-up events. Multi-hit patterns are also supported for other applications. Time measurements are extracted off chip at the maximum throughput of 40 MHz. The dynamic range is 14 bits. It has been fabricated in 0.8 μm BiCMOS technology. Time critical inputs are PECL compatible whereas other signals are CMOS compatible. A second application specific integrated circuit (ASIC) has been developed which translates NIM electrical levels to PECL ones. Both circuits are used to assemble board level TDCs complying with industry standards like VME, NIM and PCI.

  3. Real-time RMS active damping augmentation: Heavy and very light payload evaluations

    NASA Technical Reports Server (NTRS)

    Demeo, Martha E.; Gilbert, Michael G.; Lepanto, Janet A.; Flueckiger, Karl W.; Bains, Elizabeth M.; Jensen, Mary C.

    1994-01-01

    Controls-Structures Integration Technology has been applied to the Space Shuttle Remote Manipulator System (RMS) to improve on-orbit performance. The objective was to actively damp undesired oscillatory motions of the RMS following routine payload maneuvering and Shuttle attitude control thruster firings. Simulation of active damping was conducted in the real-time, man-in-the-loop Systems Engineering Simulator at NASA's Johnson Space Center. The simulator was used to obtain qualitative and quantitative data on active damping performance from astronaut operators. Using a simulated three-axis accelerometer mounted on the RMS, 'sensed' vibration motions were used to generate joint motor commands that reduced the unwanted oscillations. Active damping of the RMS with heavy and light attached payloads was demonstrated in this study. Five astronaut operators examined the performance of active damping following operator commanded RMS maneuvers and Shuttle thruster firings. Noticeable improvements in the damping response of the RMS with the heavy, Hubble Space Telescope payload and the very light, astronaut in Manipulator Foot Restraint payload were observed. The potential of active damping to aid in precisely maneuvering payloads was deemed significant.

  4. RMS active damping augmentation

    NASA Technical Reports Server (NTRS)

    Gilbert, Michael G.; Scott, Michael A.; Demeo, Martha E.

    1992-01-01

    The topics are presented in viewgraph form and include: RMS active damping augmentation; potential space station assembly benefits to CSI; LaRC/JSC bridge program; control law design process; draper RMS simulator; MIMO acceleration control laws improve damping; potential load reduction benefit; DRS modified to model distributed accelerations; accelerometer location; Space Shuttle aft cockpit simulator; simulated shuttle video displays; SES test goals and objectives; and SES modifications to support RMS active damping augmentation.

  5. High resolution time interval meter

    DOEpatents

    Martin, A.D.

    1986-05-09

    Method and apparatus are provided for measuring the time interval between two events to a higher resolution than reliability available from conventional circuits and component. An internal clock pulse is provided at a frequency compatible with conventional component operating frequencies for reliable operation. Lumped constant delay circuits are provided for generating outputs at delay intervals corresponding to the desired high resolution. An initiation START pulse is input to generate first high resolution data. A termination STOP pulse is input to generate second high resolution data. Internal counters count at the low frequency internal clock pulse rate between the START and STOP pulses. The first and second high resolution data are logically combined to directly provide high resolution data to one counter and correct the count in the low resolution counter to obtain a high resolution time interval measurement.

  6. How to squeeze high quantum efficiency and high time resolution out of a SPAD

    NASA Technical Reports Server (NTRS)

    Lacaita, A.; Zappa, F.; Cova, Sergio; Ripamonti, Giancarlo; Spinelli, A.

    1993-01-01

    We address the issue whether Single-Photon Avalanche Diodes (SPADs) can be suitably designed to achieve a trade-off between quantum efficiency and time resolution performance. We briefly recall the physical mechanisms setting the time resolution of avalanche photodiodes operated in single-photon counting, and we give some criteria for the design of SPADs with a quantum efficiency better than l0 percent at 1064 nm together with a time resolution below 50 ps rms.

  7. Status report of RMS active damping augmentation

    NASA Technical Reports Server (NTRS)

    Gilbert, Mike; Demeo, Martha E.

    1993-01-01

    A status report of Remote Manipulator System (RMS) active damping augmentation is presented. Topics covered include: active damping augmentation; benefits of RMS ADA; simulated payload definition; sensor and actuator definition; ADA control law design; Shuttle Engineering Simulator (SES) real-time simulation; and astronaut evaluation.

  8. A model for the energy-dependent time-lag and rms of the heartbeat oscillations in GRS 1915+105

    NASA Astrophysics Data System (ADS)

    Mir, Mubashir Hamid; Misra, Ranjeev; Pahari, Mayukh; Iqbal, Naseer; Ahmad, Naveel

    2016-04-01

    Energy-dependent phase lags reveal crucial information about the causal relation between various spectral components and about the nature of the accretion geometry around the compact objects. The time-lag and the fractional root mean square (rms) spectra of GRS 1915+105 in its heartbeat oscillation class/ρ state show peculiar behaviour at the fundamental and harmonic frequencies where the lags at the fundamental show a turn around at ˜10 keV, while the lags at the harmonic do not show any turn around at least till ˜20 keV. The magnitude of lags is of the order of few seconds and hence cannot be attributed to the light travel time effects or Comptonization delays. The continuum X-ray spectra can roughly be described by a disc blackbody and a hard X-ray power-law component and from phase-resolved spectroscopy, it has been shown that the inner disc radius varies during the oscillation. Here, we propose that there is a delayed response of the inner disc radius to the accretion rate such that r_{in}(t)∝ dot{m}^β (t-τ_d). The fluctuating accretion rate drives the oscillations of the inner radius after a time delay τd while the power-law component responds immediately. We show that in such a scenario a pure sinusoidal oscillation of the accretion rate can explain not only the shape and magnitude of energy-dependent rms and time-lag spectra at the fundamental, but also the next harmonic with just four free parameters.

  9. High resolution time interval counter

    DOEpatents

    Condreva, Kenneth J.

    1994-01-01

    A high resolution counter circuit measures the time interval between the occurrence of an initial and a subsequent electrical pulse to two nanoseconds resolution using an eight megahertz clock. The circuit includes a main counter for receiving electrical pulses and generating a binary word--a measure of the number of eight megahertz clock pulses occurring between the signals. A pair of first and second pulse stretchers receive the signal and generate a pair of output signals whose widths are approximately sixty-four times the time between the receipt of the signals by the respective pulse stretchers and the receipt by the respective pulse stretchers of a second subsequent clock pulse. Output signals are thereafter supplied to a pair of start and stop counters operable to generate a pair of binary output words representative of the measure of the width of the pulses to a resolution of two nanoseconds. Errors associated with the pulse stretchers are corrected by providing calibration data to both stretcher circuits, and recording start and stop counter values. Stretched initial and subsequent signals are combined with autocalibration data and supplied to an arithmetic logic unit to determine the time interval in nanoseconds between the pair of electrical pulses being measured.

  10. High resolution time interval counter

    DOEpatents

    Condreva, K.J.

    1994-07-26

    A high resolution counter circuit measures the time interval between the occurrence of an initial and a subsequent electrical pulse to two nanoseconds resolution using an eight megahertz clock. The circuit includes a main counter for receiving electrical pulses and generating a binary word--a measure of the number of eight megahertz clock pulses occurring between the signals. A pair of first and second pulse stretchers receive the signal and generate a pair of output signals whose widths are approximately sixty-four times the time between the receipt of the signals by the respective pulse stretchers and the receipt by the respective pulse stretchers of a second subsequent clock pulse. Output signals are thereafter supplied to a pair of start and stop counters operable to generate a pair of binary output words representative of the measure of the width of the pulses to a resolution of two nanoseconds. Errors associated with the pulse stretchers are corrected by providing calibration data to both stretcher circuits, and recording start and stop counter values. Stretched initial and subsequent signals are combined with autocalibration data and supplied to an arithmetic logic unit to determine the time interval in nanoseconds between the pair of electrical pulses being measured. 3 figs.

  11. 14. NBS REMOTE MANIPULATOR SIMULATOR (RMS) CONTROL ROOM. THE RMS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. NBS REMOTE MANIPULATOR SIMULATOR (RMS) CONTROL ROOM. THE RMS CONTROL PANEL IS IDENTICAL TO THE SHUTTLE ORBITER AFT FLIGHT DECK WITH ALL RMS SWITCHES AND CONTROL KNOBS FOR INVOKING ANY POSSIBLE FLIGHT OPERATIONAL MODE. THIS INCLUDES ALL COMPUTER AIDED OPERATIONAL MODES, AS WELL AS FULL MANUAL MODE. THE MONITORS IN THE AFT FLIGHT DECK WINDOWS AND THE GLASSES THE OPERATOR WEARS PROVIDE A 3-D VIDEO PICTURE TO AID THE OPERATOR WITH DEPTH PERCEPTION WHILE OPERATING THE ARM. THIS IS REQUIRED BECAUSE THE RMS OPERATOR CANNOT VIEW RMS MOVEMENTS IN THE WATER WHILE AT THE CONTROL PANEL. - Marshall Space Flight Center, Neutral Buoyancy Simulator Facility, Rideout Road, Huntsville, Madison County, AL

  12. Beam distributions beyond RMS

    SciTech Connect

    Decker, F.

    1995-05-05

    The beam is often represented only by its position (mean) and the width (rms=root mean squared) of its distribution. To achieve these beam parameters in a noisy condition with high backgrounds, a Gaussian distribution with offset (4 parameters) is fitted to the measured beam distribution. This gives a very robust answer and is not very sensitive to background subtraction techniques. To get higher moments of the distribution, like skew or kurtosis, a fitting function with one or two more parameters is desired which would model the higher moments. In this paper we will concentrate on an Asymmetric Gaussian and a Super Gaussian function that will give something like the skew and the kurtosis of the distribution. This information is used to quantify special beam distribution. Some are unwanted like beam tails (skew) from transverse wakefields, higher order dispersive aberrations or potential well distortion in a damping ring. A negative kurtosis of a beam distribution describes a more rectangular, compact shape like with an over-compressed beam in {ital z} or a closed to double-horned energy distribution, while a positive kurtosis looks more like a ``Christmas tree`` and can quantify a beam mismatch after filamentation. Besides the advantages of the quantification, there are some distributions which need a further investigation like long flat tails which create background particles in a detector. In particle simulations on the other hand a simple rms number might grossly overestimate the effective size (e.g. for producing luminosity) due to a few particles which are far away from the core. This can reduce the practical gain of a big theoretical improvement in the beam size. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  13. Beam distributions beyond RMS

    SciTech Connect

    Decker, F.J.

    1994-09-01

    The beam is often represented only by its position (mean) and the width (rms = root mean squared) of its distribution. To achieve these beam parameters in a noisy condition with high backgrounds, a Gaussian distribution with offset (4 parmeters) is fitted to the measured beam distribution. This gives a very robust answer and is not very sensitive to background subtraction techniques. To get higher moments of the distribution, like skew or kurtosis, a fitting function with one or two more parameters is desired which would model the higher moments. In this paper we will concentrate on an Asymmetric Gaussian and a Super Gaussian function that will give something like the skew and the kurtosis of the distribution. This information is used to quantify special beam distribution. Some are unwanted like beam tails (skew) from transverse wakefields, higher order dispersive aberrations or potential well distortion in a damping ring. A negative kurtosis of a beam distribution describes a more rectangular, compact shape like with an over-compressed beam in z or a closed to double-homed energy distribution, while a positive kurtosis looks more like a ``Christmas tree`` and can quantify a beam mismatch after filamentation. Besides the advantages of the quantification, there are some distributions which need a further investigation like long flat tails which create background particles in a detector. In particle simulations on the other hand a simple rms number might grossly overestimate the effective size (e.g. for producing luminosity) due to a few particles which are far away from the core. This can reduce the practical gain of a big theoretical improvement in the beam size.

  14. A spectral-timing analysis of the kHz QPOs in 4U 1636-53: the frequency-energy resolved RMS spectrum

    NASA Astrophysics Data System (ADS)

    Ribeiro, Evandro M.; Mendez, Mariano; Zhang, Guo-Bao; De Avellar, Márcio G. B.

    2016-07-01

    Our understanding of quasi-periodic oscillations (QPO) has been further advanced in the last few years by the use of combined spectral and timing techniques, and it is now clear that QPO properties are closely related to the spectral state of the source in which they appear. In this work we used all the available RXTE observations of the neutron-star low-mass X-ray binary 4U~1636-53 to study the properties of the kilohertz QPO as a function of energy and frequency. By following the frequency evolution of the kHz QPOs we created frequency-resolved fractional RMS spectra. We also studied the connection between the frequency of the kHz QPOs and the parameters of the model that fits the X-ray energy spectrum. We show the dependence of the QPO properties in a multi-parameter space, and we discuss the implication of our results to the mechanism that produces the QPOs. Our results provide input to the next generation of spectral-timing models, which will help us understand the variability and the environment around the neutron star in these systems.

  15. The discovery and modeling of energy dependent time-lags and fractional RMS of heartbeat state in GRS 1915+105

    NASA Astrophysics Data System (ADS)

    Mir, Mubashir; Iqbal, Naseer; Pahari, Mayukh; Misra, Ranjeev

    2016-07-01

    We report the discovery and modeling of enigmatic Energy dependent time-lags and fractional RMS of the heartbeat state in GRS 1915+105. The time-lags reveal the crucial information related to geometry of accretion flow, the emission regions and the relation between various spectral parameters. The lag and frms at the fundamental frequency show non-monotonic behavior with energy. The lag increases up to typically ˜10 keV and later shows a reversal and in some observations becomes hard(negative). However, the lags at the harmonic increase with energy and don't show any turn around at least till ˜20 keV. The frms at harmonic has similar non-monotonic behavior as at fundamental, however the variability amplitude is lesser as expected. The lag seen here can have magnitude of the order of seconds, and thus can't be accounted by light travel time effects or comptonization delays. The continuum X-ray spectra can roughly be described by a disk blackbody and a hard X-ray power-law component and from phase resolved spectroscopy it has been shown that the inner disk radius varies during the oscillation We propose the model based on the delayed response of inner disc (DRIOD) radius to the outer accretion rate i;e r_{in}(t)∝ dot{m}^β (t-τ_d). The fluctuating accretion rate varies the inner disk after a certain time delay t_d which could be of the order of the viscous propagation delays. The model very well explains the observed shape and nature of lags and frms at fundamental and harmonic frequencies. We present here the series of observations that constrain the four free parameters of our model. These parameters contain the vital information related to the nature of accretion flow in a highly periodic state like a heartbeat state.

  16. Tuneable Current Mode RMS Detector

    NASA Astrophysics Data System (ADS)

    Petrović, Predrag B.

    2015-01-01

    A new realization of RMS detector, employing two CCCIIs (controlled current conveyors), metal-oxide-semiconductor transistors and single grounded capacitor is present in this paper, without any external resistors and components matching requirements. The proposed circuit can be applied in measuring the RMS value of periodic, band-limited signals. The proposed circuit is very appropriate to further develop into integrated circuits. The errors related to the signal processing and errors bound were investigated and provided. To verify the theoretical analysis, the circuit PSpice simulations have also been included, showing good agreement with the theory.

  17. A time digitizer CMOS gate-array with a 250 ps time resolution

    SciTech Connect

    Arai, Yasuo

    1996-02-01

    Recent high-energy physics experiments are demanding a pipeline (deadtime-less) time-to-digital converter (TDC) with a time resolution of better than 500 ps and a double-pulse resolution of less than 30 ns. The TDC must keep all of the timing history until a trigger signal arrives about 3 {micro}s later. In large experiments, since the number of channels used is more than 100 k, the device must have a low power dissipation, a high circuit density and a low cost. A pipelined time digitizer CMOS gate-array has been developed using 0.5 {micro}m Sea-of-Gate technology. Precise timing signals which are used to sample input signals are generated from 32 taps of an asymmetric ring oscillator. The frequency of the oscillator is controlled by a phase-locked loop (PLL) circuit which runs in the 10--50 MHz frequency range. A test chip has been developed and tested; a time resolution of 250 ps rms at 40 MHz clock was measured. The chip has 4 channels and encoding circuits for both the rising and the falling edges of the input signals. The chip has 128-word dual-port memories, allowing the histories of the input signals to be stored and causing no deadtime for the conversion.

  18. A method for coincidence timing resolution enhancement

    NASA Astrophysics Data System (ADS)

    Ermis, E. E.; Celiktas, C.; Pilicer, E.

    2016-05-01

    A method including the coincidence time resolution improvement for a TOF/positron emission tomography system was suggested. The spectrometer for this aim was composed of two NaI(Tl) and two plastic scintillation detectors. Experimental results were supported by FLUKA Monte Carlo simulation program by constructing the detector setup in software medium. Present experimental results verified our previous results and conclusions obtained from the suggested method. It was concluded that better resolutions would help the improvement not only on the TOF gain but also on the spatial resolution, leading to better images and helping the Physician in his/her diagnosis and treatment.

  19. Remote metrology system (RMS) design concept

    SciTech Connect

    1995-10-19

    A 3D remote metrology system (RMS) is needed to map the interior plasma-facing components of the International Thermonuclear Experimental Reactor (ITER). The performance and survival of these components within the reactor vessel are strongly dependent on their precise alignment and positioning with respect to the plasma edge. Without proper positioning and alignment, plasma-facing surfaces will erode rapidly. A RMS design involving Coleman Research Corporation (CRC) fiber optic coherent laser radar (CLR) technology is examined in this study. The fiber optic CLR approach was selected because its high precision should be able to meet the ITER 0.1 mm accuracy requirement and because the CLR`s fiber optic implementation allows a 3D scanner to operate remotely from the RMS system`s vulnerable components. This design study has largely verified that a fiber optic CLR based RMS can survive the ITER environment and map the ITER interior at the required accuracy at a one measurement/cm{sup 2} density with a total measurement time of less than one hour from each of six or more vertically deployed measurement probes. The design approach employs a sealed and pressurized measurement probe which is attached with an umbilical spiral bellows conduit. This conduit bears fiber optic and electronic links plus a stream of air to lower the temperature in the interior of the probe. Lowering the probe temperature is desirable because probe electromechanical components which could survive the radiation environment often were not rated for the 200 C temperature. The tip of the probe whose outer shell has a flexible bellows joint can swivel in two degrees of freedom to allow mapping operations at each probe deployment level. This design study has concluded that the most successful scanner design will involve a hybrid AO beam deflector and mechanical scanner.

  20. The TDCpix readout ASIC: A 75 ps resolution timing front-end for the NA62 Gigatracker hybrid pixel detector

    NASA Astrophysics Data System (ADS)

    Kluge, A.; Aglieri Rinella, G.; Bonacini, S.; Jarron, P.; Kaplon, J.; Morel, M.; Noy, M.; Perktold, L.; Poltorak, K.

    2013-12-01

    The TDCpix is a novel pixel readout ASIC for the NA62 Gigatracker detector. NA62 is a new experiment being installed at the CERN Super Proton Synchrotron. Its Gigatracker detector shall provide on-beam tracking and time stamping of individual particles with a time resolution of 150 ps rms. It will consist of three tracking stations, each with one hybrid pixel sensor. The peak flow of particles crossing the detector modules reaches 1.27 MHz/mm2 for a total rate of about 0.75 GHz. Ten TDCpix chips will be bump-bonded to every silicon pixel sensor. Each chip shall perform time stamping of 100 M particle hits per second with a detection efficiency above 99% and a timing accuracy better than 200 ps rms for an overall three-station-setup time resolution of better than 150 ps. The TDCpix chip has been designed in a 130 nm CMOS technology. It will feature 45×40 square pixels of 300×300 μm2 and a complex End of Column peripheral region including an array of TDCs based on DLLs, four high speed serializers, a low-jitter PLL, readout and control circuits. This contribution will describe the complete design of the final TDCpix ASIC. It will discuss design choices, the challenges faced and some of the lessons learned. Furthermore, experimental results from the testing of circuit prototypes will be presented. These demonstrate the achievement of key performance figures such as a time resolution of the processing chain of 75 ps rms with a laser sent to the center of the pixel and the capability of time stamping charged particles with an overall resolution below 200 ps rms.

  1. 10 microsecond time resolution studies of Cygnus X-1

    SciTech Connect

    Wen, H.C.

    1997-06-01

    Time variability analyses have been applied to data composed of event times of X-rays emitted from the binary system Cygnus X-1 to search for unique black hole signatures. The X-ray data analyzed was collected at ten microsecond time resolution or better from two instruments, the High Energy Astrophysical Observatory (HEAO) A-1 detector and the Rossi X-ray Timing Explorer (XTE) Proportional Counter Array (PCA). HEAO A-1 and RXTE/PCA collected data from 1977--79 and from 1996 on with energy sensitivity from 1--25 keV and 2--60 keV, respectively. Variability characteristics predicted by various models of an accretion disk around a black hole have been searched for in the data. Drop-offs or quasi-periodic oscillations (QPOs) in the Fourier power spectra are expected from some of these models. The Fourier spectral technique was applied to the HEAO A-1 and RXTE/PCA data with careful consideration given for correcting the Poisson noise floor for instrumental effects. Evidence for a drop-off may be interpreted from the faster fall off in variability at frequencies greater than the observed breaks. Both breaks occur within the range of Keplerian frequencies associated with the inner edge radii of advection-dominated accretion disks predicted for Cyg X-1. The break between 10--20 Hz is also near the sharp rollover predicted by Nowak and Wagoner`s model of accretion disk turbulence. No QPOs were observed in the data for quality factors Q > 9 with a 95% confidence level upper limit for the fractional rms amplitude at 1.2% for a 16 M{sub {circle_dot}} black hole.

  2. DSCOVR High Time Resolution Solar Wind Measurements

    NASA Technical Reports Server (NTRS)

    Szabo, Adam

    2012-01-01

    The Deep Space Climate Observatory (DSCOVR), previously known as Triana, spacecraft is expected to be launched in late 2014. It will carry a fluxgate magnetometer, Faraday Cup solar wind detector and a top-hat electron electrostatic analyzer. The Faraday Cup will provide an unprecedented 10 vectors/sec time resolution measurement of the solar wind proton and alpha reduced distribution functions. Coupled with the 40 vector/sec vector magnetometer measurements, the identification of specific wave modes in the solar wind will be possible for the first time. The science objectives and data products of the mission will be discussed.

  3. Incorporating Skew into RMS Surface Roughness Probability Distribution

    NASA Technical Reports Server (NTRS)

    Stahl, Mark T.; Stahl, H. Philip.

    2013-01-01

    The standard treatment of RMS surface roughness data is the application of a Gaussian probability distribution. This handling of surface roughness ignores the skew present in the surface and overestimates the most probable RMS of the surface, the mode. Using experimental data we confirm the Gaussian distribution overestimates the mode and application of an asymmetric distribution provides a better fit. Implementing the proposed asymmetric distribution into the optical manufacturing process would reduce the polishing time required to meet surface roughness specifications.

  4. Interpolating Low Time-Resolution Forecast Data

    SciTech Connect

    Shuai Lu, PNNL

    2015-11-03

    Methodology that interpolates low time-resolution data (e.g., hourly) to high time-resolution (e.g., minutely) with variability patterns extracted from historical records. Magnitude of the variability inserted into the low timeresolution data can be adjusted according to the installed capacity represented by the low time-resolution data compared to that by historical records. This approach enables detailed analysis of the impacts from wind and solar on power system intra-hour operations and balancing reserve requirements even with only hourly data. It also allows convenient creation of high resolution wind or solar generation data with various degree of variability to investigate their operational impacts. The methodology comprises of the following steps: 1. Smooth the historical data (set A) with an appropriate window length l to get its trend (set B); l can be a fraction of an hour (e.g., 15 minutes) or longer than an hour, of which the length of the variability patterns will be; 2. Extract the variable component (set C) of historical data by subtracting the smooth trend from it, i.e. set C = set A – set B 3. For each window length l of the variable component data set, find the average value x (will call it base component) of the corresponding window of the historical data set; 4. Define a series of segments (set D) that the values of data will be grouped into, e.g. (0, 0.1), (0.1, 0.2), …, (0.9, 1.0) after normalization; Link each variability pattern to a data segment based on its corresponding base component x; after this step, each data segment should be linked to multiple variability patterns after this step; 5. Use spline function to interpolate the low time-resolution forecast data (set E) to become a high time-resolution smooth curve (set F); 6. Based on the window length l , calculate the average value y in each window length of set F; find the data segment that y belongs to; then randomly select one of the variability patterns linked to this data

  5. Mutational Analysis of Branching in Pea. Evidence That Rms1 and Rms5 Regulate the Same Novel Signal1

    PubMed Central

    Morris, Suzanne E.; Turnbull, Colin G.N.; Murfet, Ian C.; Beveridge, Christine A.

    2001-01-01

    The fifth increased branching ramosus (rms) mutant, rms5, from pea (Pisum sativum), is described here for phenotype and grafting responses with four other rms mutants. Xylem sap zeatin riboside concentration and shoot auxin levels in rms5 plants have also been compared with rms1 and wild type (WT). Rms1 and Rms5 appear to act closely at the biochemical or cellular level to control branching, because branching was inhibited in reciprocal epicotyl grafts between rms5 or rms1 and WT plants, but not inhibited in reciprocal grafts between rms5 and rms1 seedlings. The weakly transgressive or slightly additive phenotype of the rms1 rms5 double mutant provides further evidence for this interaction. Like rms1, rms5 rootstocks have reduced xylem sap cytokinin concentrations, and rms5 shoots do not appear deficient in indole-3-acetic acid or 4-chloroindole-3-acetic acid. Rms1 and Rms5 are similar in their interaction with other Rms genes. Reciprocal grafting studies with rms1, rms2, and rms5, together with the fact that root xylem sap cytokinin concentrations are reduced in rms1 and rms5 and elevated in rms2 plants, indicates that Rms1 and Rms5 may control a different pathway than that controlled by Rms2. Our studies indicate that Rms1 and Rms5 may regulate a novel graft-transmissible signal involved in the control of branching. PMID:11457970

  6. Femtosecond resolution timing jitter correction on a TW scale Ti:sapphire laser system for FEL pump-probe experiments

    NASA Astrophysics Data System (ADS)

    Csatari Divall, Marta; Mutter, Patrick; Divall, Edwin J.; Hauri, Christoph P.

    2015-11-01

    Intense ultrashort pulse lasers are used for fs resolution pumpprobe experiments more and more at large scale facilities, such as free electron lasers (FEL). Measurement of the arrival time of the laser pulses and stabilization to the machine or other sub-systems on the target, is crucial for high time-resolution measurements. In this work we report on a single shot, spectrally resolved, non-collinear cross-correlator with sub-fs resolution. With a feedback applied we keep the output of the TW class Ti:sapphire amplifier chain in time with the seed oscillator to ~3 fs RMS level for several hours. This is well below the typical pulse duration used at FELs and supports fs resolution pump-probe experiments. Short term jitter and long term timing drift measurements are presented. Applicability to other wavelengths and integration into the timing infrastructure of the FEL are also covered to show the full potential of the device.

  7. Branching in Pea (Action of Genes Rms3 and Rms4).

    PubMed Central

    Beveridge, C. A.; Ross, J. J.; Murfet, I. C.

    1996-01-01

    The nonallelic ramosus mutations rms3-2 and rms4 of pea (Pisum sativum L.) cause extensive release of vegetative axillary buds and lateral growth in comparison with wild-type (cv Torsdag) plants, in which axillary buds are not normally released under the conditions utilized. Grafting studies showed that the expression of the rms4 mutation in the shoot is independent of the genotype of the root-stock. In contrast, the length of the branches at certain nodes of rms3-2 plants was reduced by grafting to wild-type stocks, indicating that the wild-type Rms3 gene may control the level of a mobile substance produced in the root. This substance also appears to be produced in the shoot because Rms3 shoots did not branch when grafted to mutant rms3-2 rootstocks. However, the end product of the Rms3 gene appears to differ from that of the Rms2 gene (C.A. Beveridge, J.J. Ross, and I.C. Murfet [1994] Plant Physiol 104: 953-959) because reciprocal grafts between rms3-2 and rms2 seedlings produced mature shoots with apical dominance similar to that of rms3-2 and rms2 shoots grafted to wild-type stocks. Indole-3-acetic acid levels were not reduced in apical or nodal portions of rms4 plants and were actually elevated (up to 2-fold) in rms3-2 plants. It is suggested that further studies with these branching mutants may enable significant progress in understanding the normal control of apical dominance and the related communication between the root and shoot. PMID:12226224

  8. The High Time Resolution Radio Sky

    NASA Astrophysics Data System (ADS)

    Thornton, D.

    2013-11-01

    Pulsars are laboratories for extreme physics unachievable on Earth. As individual sources and possible orbital companions can be used to study magnetospheric, emission, and superfluid physics, general relativistic effects, and stellar and binary evolution. As populations they exhibit a wide range of sub-types, with parameters varying by many orders of magnitude signifying fundamental differences in their evolutionary history and potential uses. There are currently around 2200 known pulsars in the Milky Way, the Magellanic clouds, and globular clusters, most of which have been discovered with radio survey observations. These observations, as well as being suitable for detecting the repeating signals from pulsars, are well suited for identifying other transient astronomical radio bursts that last just a few milliseconds that either singular in nature, or rarely repeating. Prior to the work of this thesis non-repeating radio transients at extragalactic distances had possibly been discovered, however with just one example status a real astronomical sources was in doubt. Finding more of these sources was a vital to proving they were real and to open up the universe for millisecond-duration radio astronomy. The High Time Resolution Universe survey uses the multibeam receiver on the 64-m Parkes radio telescope to search the whole visible sky for pulsars and transients. The temporal and spectral resolution of the receiver and the digital back-end enable the detection of relatively faint, and distant radio sources. From the Parkes telescope a large portion of the Galactic plane can be seen, a rich hunting ground for radio pulsars of all types, while previously poorly surveyed regions away from the Galactic plane are also covered. I have made a number of pulsar discoveries in the survey, including some rare systems. These include PSR J1226-6208, a possible double neutron star system in a remarkably circular orbit, PSR J1431-471 which is being eclipsed by its companion with

  9. Astronaut Bernard Harris on RMS during EVA

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Astronaut Bernard A. Harris, Jr., payload commander, standing on a foot restraint attached to the Remote Manipulator System (RMS) arm carries astronaut C. Michael Foale, mission specialist, during their shared extravehicular activity (EVA) in the Space Shuttle Discovery's cargo bay.

  10. The time resolution of the St Petersburg paradox

    PubMed Central

    Peters, Ole

    2011-01-01

    A resolution of the St Petersburg paradox is presented. In contrast to the standard resolution, utility is not required. Instead, the time-average performance of the lottery is computed. The final result can be phrased mathematically identically to Daniel Bernoulli's resolution, which uses logarithmic utility, but is derived using a conceptually different argument. The advantage of the time resolution is the elimination of arbitrary utility functions. PMID:22042904

  11. Extratropical transitioning in the RMS Japan typhoon wind field model

    NASA Astrophysics Data System (ADS)

    Loridan, Thomas; Scherer, Emilie; Khare, Shree

    2013-04-01

    Given its meridional extent and location within the Pacific basin, Japan is regularly impacted by strong winds from cyclones at different stages of their lifecycle. To quantify the associated risk of damage to properties, catastrophe models such as the ones developed by RMS aim to simulate wind fields from thousands of stochastic storms that extrapolate historical events. In a recent study using 25 years of reanalysis data, Kitabatake (2011) estimated that 40 % of all Pacific tropical cyclones completed their transition as an extra tropical system. From a cat modelling point of view it is the increase in wind field asymmetry observed during these transitioning episodes that is critical, with examples like typhoon Tokage in 2004 showing the potential for damaging gusts on both sides of the storm track. In this context a compromise has to be found between the need for complex numerical models able to simulate wind field variability around the cyclone during its entire evolution, and obvious running time constrains. The RMS wind field model is based on an optimized version of the Willoughby parametric profile (Willoughby et al., 2006) which requires calibration against targets representative of cyclone wind fields throughout their lifecycle. We here present the different sources of data involved in the development of this model. This includes (1) satellite products to characterize wind fields from fully tropical storms, (2) high resolution simulations of key transitioning events using the WRF mesoscale model to complement the database at other stages (i.e. for transitioning and fully extra tropical wind fields), and (3) reanalysis data which can be used with Hart (2003)'s cyclone phase space methodology to provide an estimate of the mean duration of transitioning episodes in the Pacific. Kitabatake, N., 2011: Climatology of extratropical transition of tropical cyclones in the Western North Pacific defined by using cyclone phase space. J. Meteor. Soc. Japan, 89, 309

  12. Active damping application to the shuttle RMS

    NASA Technical Reports Server (NTRS)

    Gilbert, Michael G.; Scott, Michael A.; Kenny, Sean P.

    1991-01-01

    Control Structure Interaction (CSI) is a relatively new technology developed over the last 10 to 15 years for application to large flexible space vehicles. The central issue is recognition that high performance control systems necessary for good spacecraft performance may adversely interact with the dynamics of the spacecraft structures, a problem increasingly aggravated by the large size and reduced stiffness of modern spacecraft structural designs. The CSI analysis and design methods were developed to avoid interactions while maintaining spacecraft performance without exceeding structural capabilities, but they remain largely unvalidated by hardware experiments or demonstrations, particularly in-space flight demonstrations. One recent proposal for a low cost flight validation of CSI technology is to demonstrate active damping augmentation of the Space Shuttle Remote Manipulator System (RMS). An analytical effort to define the potential for such an active damping augmentation demonstration to improve the structural dynamic response of the RMS following payload maneuvers is described. It is hoped that this study will lead to an actual inflight CSI test with the RMS using existing shuttle hardware to the maximum extent possible. By using the existing hardware, the flight demonstration results may eventually be of direct benefit to actual Space Shuttle RMS operations, especially during the construction of the Space Station Freedom.

  13. The rms-flux relations in different branches in Cyg X-2

    NASA Astrophysics Data System (ADS)

    Li, Z. B.; Song, L. M.; Qu, J. L.; Lei, Y. J.; Nie, J. Y.; Zhang, C. M.

    2012-10-01

    In this paper, the rms-flux (root mean square-flux) relation along the Z-track of the bright Z-Source Cyg X-2 is analyzed using the observational data of Rossi X-ray Timing Explorer (RXTE). Three types of rms-flux relations, i.e. positive, negative, and `arch'-like correlations are found in different branches. The rms is positively correlated with flux in normal branch (NB), but anti-correlated in the vertical horizontal branch (VHB). The rms-flux relation shows an `arch'-like shape in the horizontal branch (HB). We also try to explain this phenomenon using existing models.

  14. Quality control of the RMS US flood model

    NASA Astrophysics Data System (ADS)

    Jankowfsky, Sonja; Hilberts, Arno; Mortgat, Chris; Li, Shuangcai; Rafique, Farhat; Rajesh, Edida; Xu, Na; Mei, Yi; Tillmanns, Stephan; Yang, Yang; Tian, Ye; Mathur, Prince; Kulkarni, Anand; Kumaresh, Bharadwaj Anna; Chaudhuri, Chiranjib; Saini, Vishal

    2016-04-01

    The RMS US flood model predicts the flood risk in the US with a 30 m resolution for different return periods. The model is designed for the insurance industry to estimate the cost of flood risk for a given location. Different statistical, hydrological and hydraulic models are combined to develop the flood maps for different return periods. A rainfall-runoff and routing model, calibrated with observed discharge data, is run with 10 000 years of stochastic simulated precipitation to create time series of discharge and surface runoff. The 100, 250 and 500 year events are extracted from these time series as forcing for a two-dimensional pluvial and fluvial inundation model. The coupling of all the different models which are run on the large area of the US implies a certain amount of uncertainty. Therefore, special attention is paid to the final quality control of the flood maps. First of all, a thorough quality analysis of the Digital Terrain model and the river network was done, as the final quality of the flood maps depends heavily on the DTM quality. Secondly, the simulated 100 year discharge in the major river network (600 000 km) is compared to the 100 year discharge derived using extreme value distribution of all USGS gauges with more than 20 years of peak values (around 11 000 gauges). Thirdly, for each gauge the modelled flood depth is compared to the depth derived from the USGS rating curves. Fourthly, the modelled flood depth is compared to the base flood elevation given in the FEMA flood maps. Fifthly, the flood extent is compared to the FEMA flood extent. Then, for historic events we compare flood extents and flood depths at given locations. Finally, all the data and spatial layers are uploaded on geoserver to facilitate the manual investigation of outliers. The feedback from the quality control is used to improve the model and estimate its uncertainty.

  15. High time-resolution photodetectors for PET applications

    DOE PAGESBeta

    Ronzhin, Anatoly

    2016-02-01

    This paper describes recent developments aiming at the improvement of the time resolution of photodetectors used in positron emission tomography (PET). Promising photodetector candidates for future PET-time-of-flight (TOF) applications are also discussed.

  16. Astronaut Jeffrey Hoffman on RMS robot arm during HST repairs

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Astronaut Jeffrey A. Hoffman, anchored to a foot restraint on the end of the Endeavour's Remote Manipulator System (RMS) robot arm, inserts the new Wide Field/Planetary Camera (WF/PC2) into its place on the Hubble Space Telescope (HST). Astronaut F. Story Musgrave, who shared the duties of replacing the camera, is partially visible at right edge of frame. Electronic still photography is technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality.

  17. ORFEUSSPAS captured by RMS prior to final berthing on Flight Day eight

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The Orbiting Retrievable Far and Extreme Ultraviolet Spectrometer (ORFEUS) with its Shuttle Pallet Satellite (SPAS) carrier is held on the end of the Remote Manipulator System (RMS) arm prior to its final berthing on eighth day of flight. A short time earlier, the RMS had assisted in capturing the ORFEUS/SPAS tandem following several days of free-flight.

  18. A high-resolution time-to-digital converter using a three-level resolution

    NASA Astrophysics Data System (ADS)

    Dehghani, Asma; Saneei, Mohsen; Mahani, Ali

    2016-08-01

    In this article, a three-level resolution Vernier delay line time-to-digital converter (TDC) was proposed. The proposed TDC core was based on the pseudo-differential digital architecture that made it insensitive to nMOS and pMOS transistor mismatches. It also employed a Vernier delay line (VDL) in conjunction with an asynchronous read-out circuitry. The time interval resolution was equal to the difference of delay between buffers of upper and lower chains. Then, via the extra chain included in the lower delay line, resolution was controlled and power consumption was reduced. This method led to high resolution and low power consumption. The measurement results of TDC showed a resolution of 4.5 ps, 12-bit output dynamic range, and integral nonlinearity of 1.5 least significant bits. This TDC achieved the consumption of 68.43 µW from 1.1-V supply.

  19. The resupply interface mechanism RMS compatibility test

    NASA Technical Reports Server (NTRS)

    Jackson, Stewart W.; Gallo, Frank G.

    1990-01-01

    Spacecraft on-orbit servicing consists of exchanging components such as payloads, orbital replacement units (ORUs), and consumables. To accomplish the exchange of consumables, the receiving vehicle must mate to the supplier vehicle. Mating can be accomplished by a variety of docking procedures. However, these docking schemes are mission dependent and can vary from shuttle bay berthing to autonomous rendezvous and docking. Satisfying the many docking conditions will require use of an innovative docking device. The device must provide fluid, electrical, pneumatic and data transfer between vehicles. Also, the proper stiffness must be obtained and sustained between the vehicles. A device to accomplish this, the resupply interface mechanism (RIM), was developed. The RIM is a unique device because it grasps the mating vehicle, draws the two vehicles together, simultaneously mates all connectors, and rigidizes the mating devices. The NASA-Johnson Manipulator Development Facility was used to study how compatible the RIM is to on orbit docking and berthing. The facility contains a shuttle cargo bay mockup with a remote manipulator system (RMS). This RMS is used to prepare crew members for shuttle missions involving spacecraft berthing operations. The MDF proved to be an excellant system for testing the RIM/RMS compatibility. The elements examined during the RIM JSC test were: RIM gross and fine alignment; berthing method sequence; visual cuing aids; utility connections; and RIM overall performance. The results showed that the RIM is a good device for spacecraft berthing operations. Mating was accomplished during every test run and all test operators (crew members) felt that the RIM is an effective device. The purpose of the JSC RIM test and its results are discussed.

  20. Time multiplexing super resolution using a Barker-based array.

    PubMed

    Ilovitsh, Asaf; Preter, Eyal; Levanon, Nadav; Zalevsky, Zeev

    2015-01-15

    We propose the use of a new encoding mask in order to improve the performance of the conventional time multiplexing super resolution method. The resolution improvement is obtained using a 2D Barker-based array that is placed upon the object and shifted laterally. The Barker-based array is a 2D generalization of the standard 1D Barker code. The Barker-based array has stable autocorrelation sidelobes, making it ideal for the encoding process. A sequence of low resolution images are captured at different positions of the array, and are decoded properly using the same array. After removing the low resolution image from the resulting reconstruction, a high resolution image is established. The proposed method is presented analytically, demonstrated via numerical simulation, and validated by laboratory experiment.

  1. Time multiplexing super resolution using a Barker-based array.

    PubMed

    Ilovitsh, Asaf; Preter, Eyal; Levanon, Nadav; Zalevsky, Zeev

    2015-01-15

    We propose the use of a new encoding mask in order to improve the performance of the conventional time multiplexing super resolution method. The resolution improvement is obtained using a 2D Barker-based array that is placed upon the object and shifted laterally. The Barker-based array is a 2D generalization of the standard 1D Barker code. The Barker-based array has stable autocorrelation sidelobes, making it ideal for the encoding process. A sequence of low resolution images are captured at different positions of the array, and are decoded properly using the same array. After removing the low resolution image from the resulting reconstruction, a high resolution image is established. The proposed method is presented analytically, demonstrated via numerical simulation, and validated by laboratory experiment. PMID:25679834

  2. Femtosecond resolution timing jitter correction on a TW scale Ti:sapphire laser system for FEL pump-probe experiments.

    PubMed

    Csatari Divall, Marta; Mutter, Patrick; Divall, Edwin J; Hauri, Christoph P

    2015-11-16

    Intense ultrashort pulse lasers are used for fs resolution pump-probe experiments more and more at large scale facilities, such as free electron lasers (FEL). Measurement of the arrival time of the laser pulses and stabilization to the machine or other sub-systems on the target, is crucial for high time-resolution measurements. In this work we report on a single shot, spectrally resolved, non-collinear cross-correlator with sub-fs resolution. With a feedback applied we keep the output of the TW class Ti:sapphire amplifier chain in time with the seed oscillator to ~3 fs RMS level for several hours. This is well below the typical pulse duration used at FELs and supports fs resolution pump-probe experiments. Short term jitter and long term timing drift measurements are presented. Applicability to other wavelengths and integration into the timing infrastructure of the FEL are also covered to show the full potential of the device. PMID:26698475

  3. Time-resolved imaging of latent fingerprints with nanosecond resolution

    NASA Astrophysics Data System (ADS)

    Seah, L. K.; Dinish, U. S.; Ong, S. K.; Chao, Z. X.; Murukeshan, V. M.

    2004-07-01

    Imaging of latent fingerprints using time-resolved (TR) method offers a broader platform to eliminate the unwanted background emission. In this paper, a novel TR imaging technique is demonstrated and implemented, which facilitates the detection of latent fingerprints with nanosecond resolution. Simulated experiments were carried out with two overlapping fingerprints treated with two fluorescent powders having different lifetimes in nanosecond range. The dependence of the fluorescence emission intensity in nanosecond resolution of TR imaging is also revealed.

  4. Hardware interface unit for control of shuttle RMS vibrations

    NASA Technical Reports Server (NTRS)

    Lindsay, Thomas S.; Hansen, Joseph M.; Manouchehri, Davoud; Forouhar, Kamran

    1994-01-01

    Vibration of the Shuttle Remote Manipulator System (RMS) increases the time for task completion and reduces task safety for manipulator-assisted operations. If the dynamics of the manipulator and the payload can be physically isolated, performance should improve. Rockwell has developed a self contained hardware unit which interfaces between a manipulator arm and payload. The End Point Control Unit (EPCU) is built and is being tested at Rockwell and at the Langley/Marshall Coupled, Multibody Spacecraft Control Research Facility in NASA's Marshall Space Flight Center in Huntsville, Alabama.

  5. Processing time using Datatrieve-11, clunks, and FORTRAN

    SciTech Connect

    Horning, R.R.; Goode, W.E.

    1983-01-01

    Although Datatrieve-11 processes dates with 100-ns resolution using clunks, it has no provision for processing time. This paper describes a set of Datatrieve-11 procedures and FORTRAN-callable subroutines for handling time, as well as dates, expressed in clunks. Although the FORTRAN-callable subroutines use RMS modules, these modules can be extracted from the appropriate RMS library, allowing FORTRAN programs to be linked to an FCS library instead of to RMS.

  6. Time resolution studies using digital constant fraction discrimination

    NASA Astrophysics Data System (ADS)

    Fallu-Labruyere, A.; Tan, H.; Hennig, W.; Warburton, W. K.

    2007-08-01

    Digital Pulse Processing (DPP) modules are being increasingly considered to replace modular analog electronics in medium-scale nuclear physics experiments (100-1000s of channels). One major area remains, however, where it has not been convincingly demonstrated that DPP modules are competitive with their analog predecessors—time-of-arrival measurement. While analog discriminators and time-to-amplitude converters can readily achieve coincidence time resolutions in the 300-500 ps range with suitably fast scintillators and Photomultiplier Tubes (PMTs), this capability has not been widely demonstrated with DPPs. Some concern has been expressed, in fact, that such time resolutions are attainable with the 10 ns sampling times that are presently commonly available. In this work, we present time-coincidence measurements taken using a commercially available DPP (the Pixie-4 from XIA LLC) directly coupled to pairs of fast PMTs mated with either LSO or LaBr 3 scintillator crystals and excited by 22Na γ-ray emissions. Our results, 886 ps for LSO and 576 ps for LaBr 3, while not matching the best literature results using analog electronics, are already well below 1 ns and fully adequate for a wide variety of experiments. These results are shown not to be limited by the DPPs themselves, which achieved 57 ps time resolution using a pulser, but are degraded in part both by the somewhat limited number of photoelectrons we collected and by a sub-optimum choice of PMT. Analysis further suggests that increasing the sampling speed would further improve performance. We therefore conclude that DPP time-of-arrival resolution is already adequate to supplant analog processing in many applications and that further improvements could be achieved with only modest efforts.

  7. High time resolution laser induced fluorescence in pulsed argon plasma

    SciTech Connect

    Biloiu, Ioana A.; Sun Xuan; Scime, Earl E.

    2006-10-15

    A submillisecond time resolution laser induced fluorescence (LIF) method for obtaining the temporal evolution of the ion velocity distribution function in pulsed argon plasma is presented. A basic LIF system that employs a continuous laser wave pumping and lock-in aided detection of the subsequent fluorescence radiation is modified by addition of a high frequency acousto-optic modulator to provide measurements of the ion flow velocity and ion temperature in a helicon generated pulsed argon plasma with temporal resolutions as high as 30 {mu}s.

  8. STIC3 - Silicon Photomultiplier Timing Chip with picosecond resolution

    NASA Astrophysics Data System (ADS)

    Stankova, Vera; Shen, Wei; Briggl, Konrad; Chen, Huangshan; Fischer, Peter; Gil, Alejandro; Harion, Tobias; Kiworra, Volker; Munwes, Yonathan; Ritzert, Michael; Schultz-Coulon, Hans-Christian

    2015-07-01

    The diagnostic of pancreas and prostate cancer is a challenging task due to the background noise coming from the closer organs. The EndoToFPET-US project aims to combine the synergy between metabolic and anatomical (ultrasound) image in order to improve the precision in the tumor localization. The goal of the project is to develop a Positron Emission Tomography (PET) system that provides a time-of-flight resolution of 200 ps FWHM for improving the signal to noise ratio and further to improve the medical image quality. In order to achieve this purpose an ASIC has been designed for very high timing resolution in time-of-flight (ToF) applications. In this paper we present the ASIC performance and the first characterization measurements with the 64-channels prototype version (STiC3). Measurements are performed with LYSO scintillator crystal and a Multi Pixel Photon Counter (MPPC). Measurements with the chip show an analog-front-end stage jitter of 35 ps for the first photo-electron equivalent charge and reach 18 ps for the third photo-electron. Coincidence time resolution (CTR) of 240 ps FWHM is measured with 3.1×3.1×15 mm3 LYSO crystal and 50 μm pixel pitch MPPC. Further optimization including the Time-to-Digital Converter (TDC) non-linearity corrections and setup fine tuning are ongoing for achieving the desired CTR of 200 ps FWHM.

  9. Geiger-mode Avalanche Photodiodes for High Time Resolution Astrophysics

    NASA Astrophysics Data System (ADS)

    Phelan, Don; Morrison, Alan P.

    Geiger-mode Avalanche Photodiodes (GM-APDs) are establishing themselves as potential candidates for the broad temporal range covered in high time resolution astrophysics (HTRA). These detectors have already been employed in astronomical instrumentation and significant results have been obtained to date. Their high time resolution and quantum efficiency make these single photon event counting detectors ideal for observations of stochastic phenomena, and ultimately for extreme HTRA observations. In this chapter, we review the technology and to illustrate their potential we briefly touch on specific science goals and astronomical applications. We then focus on the fabrication and characterisation of GM-APDs, and discuss the development and challenges posed in designing array devices.

  10. The time resolution domain of stellar radio astronomy

    NASA Technical Reports Server (NTRS)

    Bookbinder, J.

    1985-01-01

    The high time resolution (HTR) radio observation of late-type stars and RS CVn systems is discussed. Some examples of these sources are addressed, identifying what information HTR observations can provide. HTR can provide important information on flares in late-type stars, and can be used to study coronal structure and the particle acceleration mechanism in these stars. The possible use of HTR to establish the nature of quiescent emission form RS CVn systems is discussed.

  11. High frequency resolution terahertz time-domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Sangala, Bagvanth Reddy

    2013-12-01

    A new method for the high frequency resolution terahertz time-domain spectroscopy is developed based on the characteristic matrix method. This method is useful for studying planar samples or stack of planar samples. The terahertz radiation was generated by optical rectification in a ZnTe crystal and detected by another ZnTe crystal via electro-optic sampling method. In this new characteristic matrix based method, the spectra of the sample and reference waveforms will be modeled by using characteristic matrices. We applied this new method to measure the optical constants of air. The terahertz transmission through the layered systems air-Teflon-air-Quartz-air and Nitrogen gas-Teflon-Nitrogen gas-Quartz-Nitrogen gas was modeled by the characteristic matrix method. A transmission coefficient is derived from these models which was optimized to fit the experimental transmission coefficient to extract the optical constants of air. The optimization of an error function involving the experimental complex transmission coefficient and the theoretical transmission coefficient was performed using patternsearch algorithm of MATLAB. Since this method takes account of the echo waveforms due to reflections in the layered samples, this method allows analysis of longer time-domain waveforms giving rise to very high frequency resolution in the frequency-domain. We have presented the high frequency resolution terahertz time-domain spectroscopy of air and compared the results with the literature values. We have also fitted the complex susceptibility of air to the Lorentzian and Gaussian functions to extract the linewidths.

  12. Sensitivity of The High-resolution Wam Model With Respect To Time Step

    NASA Astrophysics Data System (ADS)

    Kasemets, K.; Soomere, T.

    The northern part of the Baltic Proper and its subbasins (Bothnian Sea, the Gulf of Finland, Moonsund) serve as a challenge for wave modellers. In difference from the southern and the eastern parts of the Baltic Sea, their coasts are highly irregular and contain many peculiarities with the characteristic horizontal scale of the order of a few kilometres. For example, the northern coast of the Gulf of Finland is extremely ragged and contains a huge number of small islands. Its southern coast is more or less regular but has up to 50m high cliff that is frequently covered by high forests. The area also contains numerous banks that have water depth a couple of meters and that may essentially modify wave properties near the banks owing to topographical effects. This feature suggests that a high-resolution wave model should be applied for the region in question, with a horizontal resolution of an order of 1 km or even less. According to the Courant-Friedrich-Lewy criterion, the integration time step for such models must be of the order of a few tens of seconds. A high-resolution WAM model turns out to be fairly sensitive with respect to the particular choice of the time step. In our experiments, a medium-resolution model for the whole Baltic Sea was used, with the horizontal resolution 3 miles (3' along latitudes and 6' along longitudes) and the angular resolution 12 directions. The model was run with steady wind blowing 20 m/s from different directions and with two time steps (1 and 3 minutes). For most of the wind directions, the rms. difference of significant wave heights calculated with differ- ent time steps did not exceed 10 cm and typically was of the order of a few per cents. The difference arose within a few tens of minutes and generally did not increase in further computations. However, in the case of the north wind, the difference increased nearly monotonously and reached 25-35 cm (10-15%) within three hours of integra- tion whereas mean of significant wave

  13. Heterodyning Time Resolution Boosting for Velocimetry and Reflectivity Measurements

    SciTech Connect

    Erskine, D J

    2004-08-02

    A theoretical technique is described for boosting the temporal resolving power by several times, of detectors such as streak cameras in experiments that measure light reflected from or transmitted through a target, including velocity interferometer (VISAR) measurements. This is a means of effectively increasing the number of resolvable time bins in a streak camera record past the limit imposed by input slit width and blur on the output phosphor screen. The illumination intensity is modulated sinusoidally at a frequency similar to the limiting time response of the detector. A heterodyning effect beats the high frequency science signal down a lower frequency beat signal, which is recorded together with the conventional science signal. Using 3 separate illuminating channels having different phases, the beat term is separated algebraically from the conventional signal. By numerically reversing the heterodyning, and combining with the ordinary signal, the science signal can be reconstructed to better effective time resolution than the detector used alone. The effective time resolution can be approximately halved for a single modulation frequency, and further decreased inversely proportional to the number of independent modulation frequencies employed.

  14. A high resolution Timing Counter for the MEG II experiment

    NASA Astrophysics Data System (ADS)

    De Gerone, M.; Bevilacqua, A.; Biasotti, M.; Boca, G.; Cattaneo, P. W.; Gatti, F.; Nishimura, M.; Ootani, W.; Pizzigoni, G.; Rossella, M.; Shibata, N.; Siccardi, F.; Simonetta, M.; Uchiyama, Y.; Yoshida, K.

    2016-07-01

    The development of a Timing Counter detector designed for the MEGII upgrade of the MEG experiment, which strives to improve the sensitivity on the μ+ →e+ γ decay of an order of magnitude, is presented. It is based on two sets of counters (sectors) arranged on a semi-cylindrical structure; each sector consists of 256 counters. Each counter consists of tile of fast scintillator with a dual-side read-out based on SiPM arrays in series connection. The high granularity has two advantages: optimized size for achieving high resolution (75 ps) for the single counter, and a signal e+ crosses several counters, so that resolution improves by averaging multiple time measurements. A prototype has been built and tested both in BTF and PSI facilities in order to prove the multi-hit scheme in MEG-like beam conditions. A 35 ps resolution with eight hits has been obtained with a e+ beam at 100 kHz. The first sector will be tested in the MEG II pre-engineering run planned at the end of 2015.

  15. Temporal resolution limits of time-to-frequency transformations.

    PubMed

    Fernández-Pousa, Carlos R

    2006-10-15

    Time-to-frequency converters are devices that transfer the intensity of a light pulse to its spectrum. The two architectures of these converters are studied: a dispersive line followed by a phase modulator and a single time lens operating in the spectral Fraunhofer regime. These two configurations are shown not to be equivalent in general: the first one provides an incoherent time-to-frequency mapping, whereas the second depends on the degree of coherence of the pulse. In this case, the recorded spectrum is the intensity of a partially coherent residually dispersed pulse, and the spectral Fraunhofer condition is the requirement of negligible residual dispersion. Converters operated outside the spectral Fraunhofer limit can achieve a subpicosecond resolution with moderate time-lens phase factors. Their use for pulse characterization is briefly analyzed. PMID:17001396

  16. Astronaut Claude Nicollier participates in RMS training at MSFC

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Swiss scientits Claude Nicollier (left), STS-61 mission specialist, waits his turn at the controls for the remote manipulator system (RMS) during a training session in the Neutral Buoyancy Simulator at Marshall Space Flight Center (MSFC). Mark Norman of MSFC has control of the RMS in this frame.

  17. Astronaut Ellen Ochoa at RMS controls on aft flight deck

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Astronaut Ellen Ochoa, payload commander, on the Space Shuttle Atlantis' aft flight deck, has just completed an operations at the controls for the Remote Manipulator System (RMS) arm while working in chorus with astronaut Donald R. McMonagle. McMonagle, mission commander, is seen here at his station on the forward flight deck. An RMS operations checklist floats in front of Ochoa.

  18. STS 51-F Mission Specialist Anthony England trains on RMS

    NASA Technical Reports Server (NTRS)

    1985-01-01

    STS 51-F Mission Specialist Anthony England trains on remote manipulator system (RMS) in the Shuttle mockup and integration laboratory in bldg 9A. He is using the closed circuit television monitors on his right to view the operations he is performing with the RMS.

  19. High-resolution time-frequency distributions for fall detection

    NASA Astrophysics Data System (ADS)

    Amin, Moeness G.; Zhang, Yimin D.; Boashash, Boualem

    2015-05-01

    In this paper, we examine the role of high-resolution time-frequency distributions (TFDs) of radar micro-Doppler signatures for fall detection. The work supports the recent and rising interest in using emerging radar technology for elderly care and assisted living. Spectrograms have been the de facto joint-variable signal representation, depicting the signal power in both time and frequency. Although there have been major advances in designing quadratic TFDs which are superior to spectrograms in terms of detailing the local signal behavior, the contributions of these distributions in the area of human motion classifications and their offerings in enhanced feature extractions have not yet been properly evaluated. The main purpose of this paper is to show the effect of using high-resolution TFD kernels, in lieu of spectrogram, on fall detection. We focus on the extended modified B-distribution (EMBD) and exploit the level of details it provides as compared with the coarse and smoothed time-frequency signatures offered by spectrograms.

  20. Review of the ultrafast time resolution photopolarimeters based on SPADs

    NASA Astrophysics Data System (ADS)

    Słowikowska, Aga; Kanbach, Gottfried; Goździewski, Krzysztof; Krzeszowski, Krzysztof; Rau, Arne

    2014-02-01

    We review photopolarimeters that are based on the Single Photon Avalanche Diodes (SPADs) and were designed, built, developed, and extensively used for high time resolution studies of astrophysical sources. Examples of such detectors are OPTIMA, GASP, AquEYE, and IquEYE which can measure the time of arrival of single optical photons with an accuracy of down to 50 picoseconds. We describe the most exciting results obtained with the SPADs detectors starting from the best existing optical polarimetric measurements of the Crab pulsar, the discovery of the first optical magnetar and its quasi-periodic oscillations, as well as a verification of exoplanets around eclipsing cataclysmic variables. Additionally, we discuss possible applications of such detectors for asteroseismology.

  1. ASIC-enabled High Resolution Optical Time Domain Reflectometer

    NASA Astrophysics Data System (ADS)

    Skendzic, Sandra

    Fiber optics has become the preferred technology in communication systems because of what it has to offer: high data transmission rates, immunity to electromagnetic interference, and lightweight, flexible cables. An optical time domain reflectometer (OTDR) provides a convenient method of locating and diagnosing faults (e.g. break in a fiber) along a fiber that can obstruct crucial optical pathways. Both the ability to resolve the precise location of the fault and distinguish between two discrete, closely spaced faults are figures of merit. This thesis presents an implementation of a high resolution OTDR through the use of a compact and programmable ASIC (application specific integrated circuit). The integration of many essential OTDR functions on a single chip is advantageous over existing commercial instruments because it enables small, lightweight packaging, and offers low power and cost efficiency. Furthermore, its compactness presents the option of placing multiple ASICs in parallel, which can conceivably ease the characterization of densely populated fiber optic networks. The OTDR ASIC consists of a tunable clock, pattern generator, precise timer, electrical receiver, and signal sampling circuit. During OTDR operation, the chip generates narrow electrical pulse, which can then be converted to optical format when coupled with an external laser diode driver. The ASIC also works with an external photodetector to measure the timing and amplitude of optical reflections in a fiber. It has a 1 cm sampling resolution, which allows for a 2 cm spatial resolution. While this OTDR ASIC has been previously demonstrated for multimode fiber fault diagnostics, this thesis focuses on extending its functionality to single mode fiber. To validate this novel approach to OTDR, this thesis is divided into five chapters: (1) introduction, (2) implementation, (3), performance of ASIC-based OTDR, (4) exploration in optical pre-amplification with a semiconductor optical amplifier, and

  2. 10 ps resolution, 160 ns full scale range and less than 1.5% differential non-linearity time-to-digital converter module for high performance timing measurements

    SciTech Connect

    Markovic, B.; Tamborini, D.; Villa, F.; Tisa, S.; Tosi, A.; Zappa, F.

    2012-07-15

    We present a compact high performance time-to-digital converter (TDC) module that provides 10 ps timing resolution, 160 ns dynamic range and a differential non-linearity better than 1.5% LSB{sub rms}. The TDC can be operated either as a general-purpose time-interval measurement device, when receiving external START and STOP pulses, or in photon-timing mode, when employing the on-chip SPAD (single photon avalanche diode) detector for detecting photons and time-tagging them. The instrument precision is 15 ps{sub rms} (i.e., 36 ps{sub FWHM}) and in photon timing mode it is still better than 70 ps{sub FWHM}. The USB link to the remote PC allows the easy setting of measurement parameters, the fast download of acquired data, and their visualization and storing via an user-friendly software interface. The module proves to be the best candidate for a wide variety of applications such as: fluorescence lifetime imaging, time-of-flight ranging measurements, time-resolved positron emission tomography, single-molecule spectroscopy, fluorescence correlation spectroscopy, diffuse optical tomography, optical time-domain reflectometry, quantum optics, etc.

  3. 10 ps resolution, 160 ns full scale range and less than 1.5% differential non-linearity time-to-digital converter module for high performance timing measurements.

    PubMed

    Markovic, B; Tamborini, D; Villa, F; Tisa, S; Tosi, A; Zappa, F

    2012-07-01

    We present a compact high performance time-to-digital converter (TDC) module that provides 10 ps timing resolution, 160 ns dynamic range and a differential non-linearity better than 1.5% LSB(rms). The TDC can be operated either as a general-purpose time-interval measurement device, when receiving external START and STOP pulses, or in photon-timing mode, when employing the on-chip SPAD (single photon avalanche diode) detector for detecting photons and time-tagging them. The instrument precision is 15 ps(rms) (i.e., 36 ps(FWHM)) and in photon timing mode it is still better than 70 ps(FWHM). The USB link to the remote PC allows the easy setting of measurement parameters, the fast download of acquired data, and their visualization and storing via an user-friendly software interface. The module proves to be the best candidate for a wide variety of applications such as: fluorescence lifetime imaging, time-of-flight ranging measurements, time-resolved positron emission tomography, single-molecule spectroscopy, fluorescence correlation spectroscopy, diffuse optical tomography, optical time-domain reflectometry, quantum optics, etc. PMID:22852708

  4. High Resolution Electron Spectroscopy with Time-of-Flight Spectrometers

    NASA Astrophysics Data System (ADS)

    Krässig, Bertold; Kanter, Elliot P.

    2015-05-01

    We have developed a parametrization based on ray-tracing calculations to convert electron time-of-flight (eTOF) to kinetic energy for the spectrometers of the LCLS-AMO end station at SLAC National Accelerator Laboratory. During the experiments the eTOF detector signals are recorded as digitized waveforms for every shot of the accelerator. With our parameterization we can analyze the waveforms on-line and convert detector hit times to kinetic energies. In this way we accumulate histograms with equally spaced bins in energy directly, rather than a posteriori converting an accumulated histogram of equally spaced flight times into a histogram of kinetic energies with unequal bin sizes. The parametrization is, of course, not a perfect replica of the ray tracing results, and the ray tracing is based on nominal dimensions, perfect alignment, detector response, and knowledge of time zero for the time-of-flight. In this presentation we will discuss causes, effects, and remedies for the observed deviations. We will present high-resolution results for the Ne KLL Auger spectrum that has been well studied and serves as a benchmark for our analysis algorithm. This work was supported by the Chemical Sciences, Geosciences, and Biosciences Division by the Office of Basic Energy Sciences, Office of Science, US Department of Energy, under Contract No. DE-AC02-06CH11357.

  5. Precision cosmology with time delay lenses: High resolution imaging requirements

    SciTech Connect

    Meng, Xiao -Lei; Treu, Tommaso; Agnello, Adriano; Auger, Matthew W.; Liao, Kai; Marshall, Philip J.

    2015-09-28

    Lens time delays are a powerful probe of cosmology, provided that the gravitational potential of the main deflector can be modeled with sufficient precision. Recent work has shown that this can be achieved by detailed modeling of the host galaxies of lensed quasars, which appear as ``Einstein Rings'' in high resolution images. The distortion of these arcs and counter-arcs, as measured over a large number of pixels, provides tight constraints on the difference between the gravitational potential between the quasar image positions, and thus on cosmology in combination with the measured time delay. We carry out a systematic exploration of the high resolution imaging required to exploit the thousands of lensed quasars that will be discovered by current and upcoming surveys with the next decade. Specifically, we simulate realistic lens systems as imaged by the Hubble Space Telescope (HST), James Webb Space Telescope (JWST), and ground based adaptive optics images taken with Keck or the Thirty Meter Telescope (TMT). We compare the performance of these pointed observations with that of images taken by the Euclid (VIS), Wide-Field Infrared Survey Telescope (WFIRST) and Large Synoptic Survey Telescope (LSST) surveys. We use as our metric the precision with which the slope γ' of the total mass density profile ρtot∝ r–γ' for the main deflector can be measured. Ideally, we require that the statistical error on γ' be less than 0.02, such that it is subdominant to other sources of random and systematic uncertainties. We find that survey data will likely have sufficient depth and resolution to meet the target only for the brighter gravitational lens systems, comparable to those discovered by the SDSS survey. For fainter systems, that will be discovered by current and future surveys, targeted follow-up will be required. Furthermore, the exposure time required with upcoming facilitites such as JWST, the Keck Next Generation Adaptive Optics System, and TMT, will

  6. Precision cosmology with time delay lenses: high resolution imaging requirements

    SciTech Connect

    Meng, Xiao-Lei; Liao, Kai; Treu, Tommaso; Agnello, Adriano; Auger, Matthew W.; Marshall, Philip J. E-mail: tt@astro.ucla.edu E-mail: mauger@ast.cam.ac.uk E-mail: dr.phil.marshall@gmail.com

    2015-09-01

    Lens time delays are a powerful probe of cosmology, provided that the gravitational potential of the main deflector can be modeled with sufficient precision. Recent work has shown that this can be achieved by detailed modeling of the host galaxies of lensed quasars, which appear as ''Einstein Rings'' in high resolution images. The distortion of these arcs and counter-arcs, as measured over a large number of pixels, provides tight constraints on the difference between the gravitational potential between the quasar image positions, and thus on cosmology in combination with the measured time delay. We carry out a systematic exploration of the high resolution imaging required to exploit the thousands of lensed quasars that will be discovered by current and upcoming surveys with the next decade. Specifically, we simulate realistic lens systems as imaged by the Hubble Space Telescope (HST), James Webb Space Telescope (JWST), and ground based adaptive optics images taken with Keck or the Thirty Meter Telescope (TMT). We compare the performance of these pointed observations with that of images taken by the Euclid (VIS), Wide-Field Infrared Survey Telescope (WFIRST) and Large Synoptic Survey Telescope (LSST) surveys. We use as our metric the precision with which the slope γ' of the total mass density profile ρ{sub tot}∝ r{sup −γ'} for the main deflector can be measured. Ideally, we require that the statistical error on γ' be less than 0.02, such that it is subdominant to other sources of random and systematic uncertainties. We find that survey data will likely have sufficient depth and resolution to meet the target only for the brighter gravitational lens systems, comparable to those discovered by the SDSS survey. For fainter systems, that will be discovered by current and future surveys, targeted follow-up will be required. However, the exposure time required with upcoming facilitites such as JWST, the Keck Next Generation Adaptive Optics System, and TMT, will

  7. The high-resolution time-of-flight spectrometer TOFTOF

    NASA Astrophysics Data System (ADS)

    Unruh, Tobias; Neuhaus, Jürgen; Petry, Winfried

    2007-10-01

    The TOFTOF spectrometer is a multi-disc chopper time-of-flight spectrometer for cold neutrons at the research neutron source Heinz Maier-Leibnitz (FRM II). After five reactor cycles of routine operation the characteristics of the instrument are reported in this article. The spectrometer features an excellent signal to background ratio due to its remote position in the neutron guide hall, an elaborated shielding concept and an s-shaped curved primary neutron guide which acts i.a. as a neutron velocity filter. The spectrometer is fed with neutrons from the undermoderated cold neutron source of the FRM II leading to a total neutron flux of ˜1010n/cm2/s in the continuous white beam at the sample position distributed over a continuous and particularly broad wavelength spectrum. A high energy resolution is achieved by the use of high speed chopper discs made of carbon-fiber-reinforced plastic. In the combination of intensity, resolution and signal to background ratio the spectrometer offers new scientific prospects in the fields of inelastic and quasielastic neutron scattering.

  8. Synthesis of rainfall time series in a high temporal resolution

    NASA Astrophysics Data System (ADS)

    Callau Poduje, Ana Claudia; Haberlandt, Uwe

    2014-05-01

    In order to optimize the design and operation of urban drainage systems, long and continuous rain series in a high temporal resolution are essential. As the length of the rainfall records is often short, particularly the data available with the temporal and regional resolutions required for urban hydrology, it is necessary to find some numerical representation of the precipitation phenomenon to generate long synthetic rainfall series. An Alternating Renewal Model (ARM) is applied for this purpose, which consists of two structures: external and internal. The former is the sequence of wet and dry spells, described by their durations which are simulated stochastically. The internal structure is characterized by the amount of rain corresponding to each wet spell and its distribution within the spell. A multivariate frequency analysis is applied to analyze the internal structure of the wet spells and to generate synthetic events. The stochastic time series must reproduce the statistical characteristics of observed high resolution precipitation measurements used to generate them. The spatio-temporal interdependencies between stations are addressed by resampling the continuous synthetic series based on the Simulated Annealing (SA) procedure. The state of Lower-Saxony and surrounding areas, located in the north-west of Germany is used to develop the ARM. A total of 26 rainfall stations with high temporal resolution records, i.e. rainfall data every 5 minutes, are used to define the events, find the most suitable probability distributions, calibrate the corresponding parameters, simulate long synthetic series and evaluate the results. The length of the available data ranges from 10 to 20 years. The rainfall series involved in the different steps of calculation are compared using a rainfall-runoff model to simulate the runoff behavior in urban areas. The EPA Storm Water Management Model (SWMM) is applied for this evaluation. The results show a good representation of the

  9. Sub-picosecond Resolution Time-to-Digital Converter

    SciTech Connect

    Ph D, Vladimir Bratov; Ph D, Vladimir Katzman; MS EE, Jeb Binkley

    2006-03-30

    Time-to-digital converters with sub-picosecond resolutions are needed to satisfy the requirements of time-on-flight measurements of the next generation of high energy and nuclear physics experiments. The converters must be highly integrated, power effective, low cost, and feature plug-and-play capabilities to handle the increasing number of channels (up to hundreds of millions) in future Department of Energy experiments. Current state-off-the-art time-to-digital converter integrated circuits do not have the sufficient degree of integration and flexibility to fulfill all the described requirements. During Phase I, the Advanced Science and Novel Technology Company in cooperation with the nuclear physics division of the Oak Ridge National Laboratory has developed the architecture of a novel time-to-digital converter with multiple channels connected to an external processor through a special interfacing block and synchronized by clock signals generated by an internal phase-locked loop. The critical blocks of the system including signal delay lines and delay-locked loops with proprietary differential delay cells, as well as the required digital code converter and the clock period counter have been designed and simulated using the advanced SiGe120 BiCMOS technological process. The results of investigations demonstrate a possibility to achieve the digitization accuracy within 1ps. ADSANTEC has demonstrated the feasibility of the proposed concept in computer simulations. The proposed system will be a critical component for the next generation of NEP experiments.

  10. Astronaut Claude Nicollier at RMS controls on aft flight deck

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Swiss Astronaut Claude Nicollier is pictured at the aft flight deck station he occupies. Among Nicollier 's responsibilities were the control of the Remote Manipulator System (RMS) during operations with the Hubble Space Telesocpe (HST).

  11. Challenger's RMS arm grasps SPAS-01 during proximity operations

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Challenger's remote manipulator system (RMS) arm grasps Shuttle pallet satellite (SPAS-01) during proximity operations. The frame shows a number of reflections on the window, located overhead in the aft flight deck.

  12. Astronaut Michael Foale on RMS arm during EVA

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Astronaut C. Michael Foale (red stripe), mission specialist, on the Remote Manipulator System (RMS) arm prepares to grab SPARTAN 204 as astronaut Bernard A. Harris Jr., payload commander, looks on during the STS-63 extravehicular activity (EVA).

  13. 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

  14. RMS ENVELOPE BACK-PROPAGATION IN THE XAL ONLINE MODEL

    SciTech Connect

    Allen, Christopher K; Sako, Hiroyuki; Ikegami, Masanori

    2009-01-01

    The ability to back-propagate RMS envelopes was added to the J-PARC XAL online model. Specifically, given an arbitrary downstream location, the online model can propagate the RMS envelopes backward to an arbitrary upstream location. This feature provides support for algorithms estimating upstream conditions from downstream data. The upgrade required significant refactoring, which we outline. We also show simulations using the new feature.

  15. Multi-time resolution analysis of speech: evidence from psychophysics.

    PubMed

    Chait, Maria; Greenberg, Steven; Arai, Takayuki; Simon, Jonathan Z; Poeppel, David

    2015-01-01

    How speech signals are analyzed and represented remains a foundational challenge both for cognitive science and neuroscience. A growing body of research, employing various behavioral and neurobiological experimental techniques, now points to the perceptual relevance of both phoneme-sized (10-40 Hz modulation frequency) and syllable-sized (2-10 Hz modulation frequency) units in speech processing. However, it is not clear how information associated with such different time scales interacts in a manner relevant for speech perception. We report behavioral experiments on speech intelligibility employing a stimulus that allows us to investigate how distinct temporal modulations in speech are treated separately and whether they are combined. We created sentences in which the slow (~4 Hz; Slow) and rapid (~33 Hz; Shigh) modulations-corresponding to ~250 and ~30 ms, the average duration of syllables and certain phonetic properties, respectively-were selectively extracted. Although Slow and Shigh have low intelligibility when presented separately, dichotic presentation of Shigh with Slow results in supra-additive performance, suggesting a synergistic relationship between low- and high-modulation frequencies. A second experiment desynchronized presentation of the Slow and Shigh signals. Desynchronizing signals relative to one another had no impact on intelligibility when delays were less than ~45 ms. Longer delays resulted in a steep intelligibility decline, providing further evidence of integration or binding of information within restricted temporal windows. Our data suggest that human speech perception uses multi-time resolution processing. Signals are concurrently analyzed on at least two separate time scales, the intermediate representations of these analyses are integrated, and the resulting bound percept has significant consequences for speech intelligibility-a view compatible with recent insights from neuroscience implicating multi-timescale auditory processing. PMID

  16. Multi-time resolution analysis of speech: evidence from psychophysics

    PubMed Central

    Chait, Maria; Greenberg, Steven; Arai, Takayuki; Simon, Jonathan Z.; Poeppel, David

    2015-01-01

    How speech signals are analyzed and represented remains a foundational challenge both for cognitive science and neuroscience. A growing body of research, employing various behavioral and neurobiological experimental techniques, now points to the perceptual relevance of both phoneme-sized (10–40 Hz modulation frequency) and syllable-sized (2–10 Hz modulation frequency) units in speech processing. However, it is not clear how information associated with such different time scales interacts in a manner relevant for speech perception. We report behavioral experiments on speech intelligibility employing a stimulus that allows us to investigate how distinct temporal modulations in speech are treated separately and whether they are combined. We created sentences in which the slow (~4 Hz; Slow) and rapid (~33 Hz; Shigh) modulations—corresponding to ~250 and ~30 ms, the average duration of syllables and certain phonetic properties, respectively—were selectively extracted. Although Slow and Shigh have low intelligibility when presented separately, dichotic presentation of Shigh with Slow results in supra-additive performance, suggesting a synergistic relationship between low- and high-modulation frequencies. A second experiment desynchronized presentation of the Slow and Shigh signals. Desynchronizing signals relative to one another had no impact on intelligibility when delays were less than ~45 ms. Longer delays resulted in a steep intelligibility decline, providing further evidence of integration or binding of information within restricted temporal windows. Our data suggest that human speech perception uses multi-time resolution processing. Signals are concurrently analyzed on at least two separate time scales, the intermediate representations of these analyses are integrated, and the resulting bound percept has significant consequences for speech intelligibility—a view compatible with recent insights from neuroscience implicating multi-timescale auditory

  17. New hemispheric geomagnetic indices α with 15 min time resolution

    NASA Astrophysics Data System (ADS)

    Chambodut, Aude; Marchaudon, Aurélie; Lathuillère, Chantal; Menvielle, Michel; Foucault, Etienne

    2015-11-01

    New subauroral α15 indices are proposed. They are based on a simple reproducible algorithm which relies on an as dense as possible network of magnetic observatories in each hemisphere. At first, the variation with time of local geomagnetic activity is determined at each magnetic station. Gathering all obtained stations' precomputed values, a normalization with corrected geomagnetic latitude is determined. Then, for each 15 min interval, magnetic activity on the horizontal component is averaged out over 15 min and corrected using this normalization, before a spline modeling of the longitudinal variation in each hemisphere is applied. Hemispheric and planetary 15 min indices are then computed by arithmetic means. Preliminary statistical results, from probability distribution function over a solar cycle and superposed epoch analysis during storms conditions, show, by comparison with am geomagnetic index series, that new α15 indices are reliable in describing subauroral magnetic activity. These new indices will suit any future user, allowing either to choose the spatial description (planetary versus hemispheric) and/or to choose the temporal resolution, knowing unambiguously all their strengths and caveats.

  18. Grief Resolution of Birthmothers in Confidential, Time-Limited Mediated, Ongoing Mediated, and Fully Disclosed Adoptions.

    ERIC Educational Resources Information Center

    Christian, Cinda L.; McRoy, Ruth G.; Grotevant, Harold D.; Bryant, Chalandra M.

    1997-01-01

    Examined grief resolution issues for birthmothers who placed infants for adoption. Found that birthmothers in fully disclosed adoptions had better resolution than with confidential and time-limited mediated adoptions, and those in ongoing mediated had better resolution than with time-limited mediated adoptions. Findings pose implications for…

  19. Time and position resolution of the scintillator strips for a muon system at future colliders

    DOE PAGESBeta

    Denisov, Dmitri; Evdokimov, Valery; Lukic, Strahinja

    2016-03-31

    In this study, prototype scintilator+WLS strips with SiPM readout for a muon system at future colliders were tested for light yield, time resolution and position resolution. Depending on the configuration, light yield of up to 36 photoelectrons per muon per SiPM has been observed, as well as time resolution of 0.45 ns and position resolution along the strip of 7.7 cm.

  20. STS-52 CANEX-2 Canadian Target Assembly (CTA) held by RMS over OV-102's PLB

    NASA Technical Reports Server (NTRS)

    1992-01-01

    In operation during STS-52 above the payload bay (PLB) of Columbia, Orbiter Vehicle (OV) 102, is the Canadian Experiment 2 (CANEX-2) Space Vision System (SVS) experiment. Target dots have been placed on the Canadian Target Assembly (CTA), a small spacecraft, in the grasp of the Canadian-built remote manipulator system (RMS) arm. With the shuttle's closed circuit television (CCTV) system, the payload specialist monitors the movement of the 4-foot by 7-foot by 1.5-foot deployed spacecraft, whose surface is covered with many sets of dots of know spacing. As the satellite moved via the RMS, the SVS computer measured the changing position of the dots and provided real-time television display of the location and orientation of the CTA. This type of information is expected to help an operator guide the RMS or the Mobile Servicing System (MSS) of the future when berthing or deploying satellites. Also visible on the RMS is another CANEX-2 payload, the Material Exposure in Low Earth Orbit (MELEO

  1. Astronaut Jerry Ross on RMS holds on to ACCESS device

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Astronaut Jerry L. Ross, anchored to the foot restraint on the remote manipulator system (RMS), holds on to the tower-like Assembly Concept for Construction of Erectable Space Structures (ACCESS) device just erected by Ross and Astronaut Sherwood Spring as the Atlantis flies over white clouds and blue ocean waters of the Atlantic.

  2. Astronaut Jerry Ross on RMS holds on to ACCESS device

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Astronaut Jerry L. Ross, anchored to the foot restraint on the remote manipulator system (RMS), holds onto the tower-like Assembly Concept for Construction of Erectable Space Structures (ACCESS) device as the Atlantis flies over white clouds and blue ocean waters.

  3. Astronaut Jerry Ross on RMS holds on to ACCESS device

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Astronaut Jerry L. Ross, anchored to the foot restraint on the remote manipulator system (RMS), approaches the tower-like Assembly Concept for Construction of Erectable Space Structures (ACCESS) device just erected by Ross and Astronaut Sherwood Spring as the Atlantis flies over white clouds and blue ocean waters of the Atlantic.

  4. SPARTAN-201 satellite lined up with RMS arm for recapture

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Backdropped against the darkness of space, the Shuttle Pointed Autonomous Research Tool for Astronomy (SPARTAN-201) satellite is lined up with Discovery's Remote Manipulator System (RMS) arm for recapture. The free-flying spacecraft had remained some 40 miles away from Discovery for over two days.

  5. Challenger's RMS arm grasps SPAS-01 during proximity operations

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Challenger's remote manipulator system (RMS) arm grasps Shuttle pallet satellite (SPAS-01) during proximity operations. Behind the SPAS-01 can be seen the clouded surface of the earth. The frame shows a number of reflections on the window, located overhead in the aft flight deck.

  6. Television camera on RMS surveys insulation on Airborne Support Equipment

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The television camera on the end effector of the Canadian-built Remote Manipulator System (RMS) is seen surveying some of the insulation on the Airborne Support Equipment (ASE). Flight controllers called for the survey following the departure of the Advanced Communications Technology Satellite (ACTS) and its Transfer Orbit Stage (TOS).

  7. Universal behavior of the interoccurrence times between losses in financial markets: Independence of the time resolution

    NASA Astrophysics Data System (ADS)

    Ludescher, Josef; Bunde, Armin

    2014-12-01

    We consider representative financial records (stocks and indices) on time scales between one minute and one day, as well as historical monthly data sets, and show that the distribution PQ(r ) of the interoccurrence times r between losses below a negative threshold -Q , for fixed mean interoccurrence times RQ in multiples of the corresponding time resolutions, can be described on all time scales by the same q exponentials, PQ(r ) ∝1 /{[1+(q -1 ) β r ] 1 /(q -1 )} . We propose that the asset- and time-scale-independent analytic form of PQ(r ) can be regarded as an additional stylized fact of the financial markets and represents a nontrivial test for market models. We analyze the distribution PQ(r ) as well as the autocorrelation CQ(s ) of the interoccurrence times for three market models: (i) multiplicative random cascades, (ii) multifractal random walks, and (iii) the generalized autoregressive conditional heteroskedasticity [GARCH(1,1)] model. We find that only one of the considered models, the multifractal random walk model, approximately reproduces the q -exponential form of PQ(r ) and the power-law decay of CQ(s ) .

  8. High resolution kinetic energy by long time-delayed core-sampling photofragment translational spectroscopy

    SciTech Connect

    Li Guosheng; Hwang, Hyun Jin; Jung, Hyun Chai

    2005-02-01

    A pulsed core-sampling photofragment translational spectroscopy (PTS) method with a long time-delay, which allows an extremely high kinetic energy resolution, is presented in this article. More commonly applying a short time delay between laser and pulsed acceleration electric field leads to a low kinetic energy resolution for the pulsed core-sampling method. This low kinetic energy resolution problem was overcome by applying a longer time delay. An absolute recoil velocity resolution of {delta}v=8 m/s and a relative kinetic energy resolution of {delta}E/E=3.6% were obtained in this experiment, by applying a time-delay of 8 {mu}s between the laser and the acceleration electric field. The vibrational distributions of the CH{sub 3} radical for the I* and I channel of CH{sub 3}I photodissociation at 266 nm were directly resolved for first time to presented an improvement of the kinetic energy resolution.

  9. STS-82 Mission Specialist Steven Hawley near RMS

    NASA Technical Reports Server (NTRS)

    1997-01-01

    STS-82 Mission Specialist Steven A. Hawley stands beside part of Discovery's Remote Manipulator System (RMS) arm, at right, which he will operate for the capture, berthing and redeployment of the Hubble Space Telescope (HST). The robotic arm also will be used as work platform for the four spacewalkers. Hawley is the prime RMS operator on the flight, which will be the second HST servicing mission. He and the other six members of the crew are making a final inspection of the payload at Launch Pad 39A before launch. STS-82 is scheduled for liftoff on Feb. 11 during a 65- minute launch window which opens at 3:56 a.m. EST.

  10. Highly segmented, high resolution time-of-flight system

    SciTech Connect

    Nayak, T.K.; Nagamiya, S.; Vossnack, O.; Wu, Y.D.; Zajc, W.A.; Miake, Y.; Ueno, S.; Kitayama, H.; Nagasaka, Y.; Tomizawa, K.; Arai, I.; Yagi, K

    1991-12-31

    The light attenuation and timing characteristics of time-of-flight counters constructed of 3m long scintillating fiber bundles of different shapes and sizes are presented. Fiber bundles made of 5mm diameter fibers showed good timing characteristics and less light attenuation. The results for a 1.5m long scintillator rod are also presented.

  11. Astronaut Susan Helms on aft flight deck with RMS controls

    NASA Technical Reports Server (NTRS)

    1994-01-01

    On the Space Shuttle Discovery's aft flight deck, astronaut Susan J. Helms handles controls for the Remote Manipulator System (RMS). The robot arm operated by Helms, who remained inside the cabin, was used to support task such as the release and retrieval of the free-flying Shuttle Pointed Autonomous Research Tool for Astronomy (SPARTAN) - 201, a six-hour space walk and the Shuttle Plume Impingement Flight Experiment (SPIFEX).

  12. STS-37 Gamma Ray Observatory (GRO) grappled by RMS

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Backdropped against the Earth's cloud-covered surface, the Gamma Ray Observatory (GRO) with its solar array (SA) panels deployed is grappled by the remote manipulator system (RMS) during STS-37 systems checkout. GRO's four complement instruments are visible: the Energetic Gamma Ray Experiment Telescope (EGRET) (at the bottom); the Imaging Compton Telescope (COMPTEL) (center); the Oriented Scintillation Spectrometer Experiment (OSSE) (top); and Burst and Transient Source Experiment (BATSE) (on four corners).

  13. SPIFEX at work on end of RMS arm

    NASA Technical Reports Server (NTRS)

    1994-01-01

    With the blue and white Earth as a backdrop 130 miles below, the Shuttle Plume Impingement Flight Experiment (SPIFEX) is at work on the end of the Remote Manipulator System (RMS) arm. The 50 feet long arm is extended to 80 feet with the temporary addition of the SPIFEX hardware. The image is exposed with a 70mm handheld Hasselblad camera from inside the Space Shuttle Discovery's crew cabin.

  14. Plasma diagnostics package (PDP) photographed in grasp of the RMS

    NASA Technical Reports Server (NTRS)

    1982-01-01

    This view shows the plasma diagnostics package (PDP) photographed by STS-3 crewmen in the grasp of the end effector of the remote manipulator system (RMS) and other components of the OSS-1 package in the aft section of the Columbia's cargo hold. Other OSS-1 payload experiments seen in the bay include the Thermal Canister Experiment, the Solar Flare X-Ray Polarimeter Experiment, the Vehicle Charging and Potential Experiment and the Induced Atmosphere Experiment.

  15. The RMS survey: resolving kinematic distance ambiguities towards a sample of compact H II regions using H I absorption

    NASA Astrophysics Data System (ADS)

    Urquhart, J. S.; Hoare, M. G.; Lumsden, S. L.; Oudmaijer, R. D.; Moore, T. J. T.; Mottram, J. C.; Cooper, H. D. B.; Mottram, M.; Rogers, H. C.

    2012-02-01

    We present high-resolution H I data obtained using the Australia Telescope Compact Array to resolve the near/far distance ambiguities towards a sample of compact H II regions from the Red MSX Source (RMS) survey. The high-resolution data are complemented with lower resolution archival H I data extracted from the Southern and Very Large Array (VLA) Galactic Plane surveys. We resolve the distance ambiguity for nearly all of the 105 sources where the continuum was strong enough to allow analysis of the H I absorption line structure. This represents another step in the determination of distances to the total RMS sample, which with over 1000 massive young stellar objects and compact H II regions is the largest and most complete sample of its kind. The full sample will allow the distribution of massive star formation in the Galaxy to be examined. Full versions of Figs 3 and 4 are only available in electronic form of the journal.

  16. It's time for a crisper image of the Face of the Earth: Landsat and climate time series for massive land cover & climate change mapping at detailed resolution.

    NASA Astrophysics Data System (ADS)

    Pons, Xavier; Miquel, Ninyerola; Oscar, González-Guerrero; Cristina, Cea; Pere, Serra; Alaitz, Zabala; Lluís, Pesquer; Ivette, Serral; Joan, Masó; Cristina, Domingo; Maria, Serra Josep; Jordi, Cristóbal; Chris, Hain; Martha, Anderson; Juanjo, Vidal

    2014-05-01

    Combining climate dynamics and land cover at a relative coarse resolution allows a very interesting approach to global studies, because in many cases these studies are based on a quite high temporal resolution, but they may be limited in large areas like the Mediterranean. However, the current availability of long time series of Landsat imagery and spatially detailed surface climate models allow thinking on global databases improving the results of mapping in areas with a complex history of landscape dynamics, characterized by fragmentation, or areas where relief creates intricate climate patterns that can be hardly monitored or modeled at coarse spatial resolutions. DinaCliVe (supported by the Spanish Government and ERDF, and by the Catalan Government, under grants CGL2012-33927 and SGR2009-1511) is the name of the project that aims analyzing land cover and land use dynamics as well as vegetation stress, with a particular emphasis on droughts, and the role that climate variation may have had in such phenomena. To meet this objective is proposed to design a massive database from long time series of Landsat land cover products (grouped in quinquennia) and monthly climate records (in situ climate data) for the Iberian Peninsula (582,000 km2). The whole area encompasses 47 Landsat WRS2 scenes (Landsat 4 to 8 missions, from path 197 to 202 and from rows 30 to 34), and 52 Landsat WRS1 scenes (for the previous Landsat missions, 212 to 221 and 30 to 34). Therefore, a mean of 49.5 Landsat scenes, 8 quinquennia per scene and a about 6 dates per quinquennium , from 1975 to present, produces around 2376 sets resulting in 30 m x 30 m spatial resolution maps. Each set is composed by highly coherent geometric and radiometric multispectral and multitemporal (to account for phenology) imagery as well as vegetation and wetness indexes, and several derived topographic information (about 10 Tbyte of data). Furthermore, on the basis on a previous work: the Digital Climatic Atlas of

  17. STS-56 remote manipulator system (RMS) recaptures SPARTAN-201 above OV-103

    NASA Technical Reports Server (NTRS)

    1993-01-01

    STS-56 remote manipulator system's (RMS') end effector grapples the Shuttle Pointed Autonomous Research Tool for Astronomy 201 (SPARTAN-201) against the blackness of space and above the payload bay (PLB) of Discovery, Orbiter Vehicle (OV) 103. SPARTAN-201, a free-flying payload, is designed to study the solar wind and part of the sun's corona. The project was conceived in the late 1970s to take advantage of the opportunity offered by the Space Shuttle to provide more observation time for the increasingly more sophisticated experiments than the five to ten minutes provided by sounding rocket flights. The RMS lifted SPARTAN-201 from its support structure and released it into space on the mission's third day. Depicted here, the recapture occurred on the mission's sixth day.

  18. Evaluation and design of a small portable EMG amplifier with potential RMS output.

    PubMed

    Shimomura, Y; Iwanaga, K; Harada, H; Katsuura, T

    1999-03-01

    The present study attempted to design and evaluate a small portable electromyogram (EMG) amplifier that can output enhanced EMG and its root mean square (RMS) value. The production and design were of a laboratory scale without any special or high cost circuit construction. The designed amplifier was actually innovated according to the actual working conditions based on physiological anthropology. The present amplifier was compared with commercially available products and proved to be of practical use. The device was installed with a sufficiently small body depicting 8-channel variable gain AC amplifier and variable time-window RMS-to-DC converter. The prototype was battery-driven and well-shielded to minimize external noise interference. PMID:10388160

  19. Single photon detection and sub-nanosecond timing resolution with RCA C31034 photomultiplier

    NASA Technical Reports Server (NTRS)

    Reisse, R.; Creecy, R.; Poultney, S. K.

    1973-01-01

    The very high quantum efficiencies and low dark count rates achieved with selected RCA C31034 photomultipliers make them attractive candidates for single photoelectron fast timing experiments. Single photoelectron plateau counting and a timing resolution of 0.60 nsec (FWHM) were obtained using fast amplifiers, constant fraction timing discriminators, and a pulsed light emitting diode. A redesign of the C31034 incorporating features of the very fast C31024 is suggested to yield even better timing resolution.

  20. Design Study of a Whole-Body PET Scanner with Improved Spatial and Timing Resolution

    PubMed Central

    Surti, S.; Shore, Adam R.; Karp, Joel S.

    2013-01-01

    Current state-of-art whole-body PET scanners achieve a system spatial resolution of 4–5 mm with limited sensitivity. Since the reconstructed spatial resolution and image quality are limited by the count statistics, there has not been a significant push for developing higher resolution whole-body PET scanners. Our goal in this study is to investigate the impact of improved spatial resolution together with time-of-flight (TOF) capability on lesion uptake estimation and lesion detectability, two important tasks in whole-body oncologic studies. The broader goal of this project is the development of a new state-of-art TOF PET scanner operating within an MRI while pushing the technology in PET system design. We performed Monte Carlo simulations to test the effects of crystal size (4 mm and 2.6 mm wide crystals), TOF timing resolution (300ps and 600ps), and 2-level depth-of-interaction (DOI) capability. Spatial resolution was calculated by simulating point sources in air at multiple positions. Results show that smaller crystals produced improved resolution, while degradation of resolution due to parallax error could be reduced with a 2-level DOI detector. Lesion phantoms were simulated to measure the contrast recovery coefficient (CRC) and area under the LROC curve (ALROC) for 0.5 cm diameter lesions with 6:1 activity uptake relative to the background. Smaller crystals produce higher CRC, leading to increased ALROC values or a reduction in scan time. Improved timing resolution provides faster CRC convergence and once again leads to an increase in ALROC value or reduced scan time. Based on our choice of timing resolution and crystal size, improved timing resolution (300ps) with larger crystals (4 mm wide) has similar ALROC as smaller crystals (2.6 mm wide) with 600ps timing resolution. A 2-level DOI measurement provides some CRC and ALROC improvement for lesions further away from the center, leading to a more uniform performance within the imaging field-of-view (FOV

  1. Rapid high-resolution spin- and time-resolved ARPES

    NASA Astrophysics Data System (ADS)

    Lin, Chiu-Yun; Gotlieb, Kenneth; Jozwiak, Chris; Hussain, Zahid; Bostwick, Aaron; Lanzara, Alessandra; Advanced Light Source, Lawrence Berkeley National Laboratory Collaboration; Graduate Group in Applied Science; Technology, University of California, Berkeley Collaboration

    2015-03-01

    A high-efficiency spin- and angle-resolved photoemission spectroscopy (spin-ARPES) spectrometer, coupled with a lab-based 6 eV laser, will be presented in this talk. Combining time-of-flight(TOF) energy measurements with low-energy exchange scattering spin polarimetry, spin-TOF ARPES achieves unprecedented measurements of near-EF physics rapidly. In addition, the successful integration of the spectrometer with the pulsed laser system demonstrates its potential for simultaneous spin- and time-resolved ARPES with pump-probe based measurements.

  2. The CU ground MAX-DOAS instrument: characterization of RMS noise limitations and first measurements near Pensacola, FL of BrO, IO, and CHOCHO

    NASA Astrophysics Data System (ADS)

    Coburn, S.; Dix, B.; Sinreich, R.; Volkamer, R.

    2011-11-01

    We designed and assembled the University of Colorado Ground Multi AXis Differential Optical Absorption Spectroscopy (CU GMAX-DOAS) instrument to retrieve bromine oxide (BrO), iodine oxide (IO), formaldehyde (HCHO), glyoxal (CHOCHO), nitrogen dioxide (NO2) and the oxygen dimer (O4) in the coastal atmosphere of the Gulf of Mexico. The detection sensitivity of DOAS measurements is proportional to the root mean square (RMS) of the residual spectrum that remains after all absorbers have been subtracted. Here we describe the CU GMAX-DOAS instrument and demonstrate that the hardware is capable of attaining RMS of ∼6 × 10-6 from solar stray light noise tests using high photon count spectra (compatible within a factor of two with photon shot noise). Laboratory tests revealed two critical instrument properties that, in practice, can limit the RMS: (1) detector non-linearity noise, RMSNLin, and (2) temperature fluctuations that cause variations in optical resolution (full width at half the maximum, FWHM, of atomic emission lines) and give rise to optical resolution noise, RMSFWHM. The non-linearity of our detector is low (∼10-2) yet - unless actively controlled - is sufficiently large to create RMSNLin of up to 2 × 10-4. The optical resolution is sensitive to temperature changes (0.03 detector pixels °C-1 at 334 nm), and temperature variations of 0.1°C can cause RMSFWHM of ~1 × 10-4. Both factors were actively addressed in the design of the CU GMAX-DOAS instrument. With an integration time of 60 s the instrument can reach RMS noise of 3 × 10-5, and typical RMS in field measurements ranged from 6 × 10-5 to 1.4 × 10-4. The CU GMAX-DOAS was set up at a coastal site near Pensacola, Florida, where we detected BrO, IO and CHOCHO in the marine boundary layer (MBL), with daytime average tropospheric vertical column densities (average of data above the detection limit), VCDs, of ∼2 × 1013 molec cm-2, 8 × 1012 molec cm-2 and 4 × 1014 molec cm-2, respectively

  3. Spectrometer employing optical fiber time delays for frequency resolution

    DOEpatents

    Schuss, Jack J.; Johnson, Larry C.

    1979-01-01

    This invention provides different length glass fibers for providing a broad range of optical time delays for short incident chromatic light pulses for the selective spatial and frequency analysis of the light with a single light detector. To this end, the frequencies of the incident light are orientated and matched with the different length fibers by dispersing the separate frequencies in space according to the respective fiber locations and lengths at the input terminal of the glass fibers. This makes the different length fibers useful in the field of plasma physics. To this end the short light pulses can be scattered by a plasma and then passed through the fibers for analyzing and diagnosing the plasma while it varies rapidly with time.

  4. STS-37 Gamma Ray Observatory (GRO) grappled by RMS

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Backdropped against the Earth's expansive desert in the Mid East, the Gamma Ray Observatory (GRO) with its solar array (SA) panels deployed is grappled by the remote manipulator system (RMS) during STS-37 systems checkout. GRO's four complement instruments are visible: the Energetic Gamma Ray Experiment Telescope (EGRET) (at the bottom); the Imaging Compton Telescope (COMPTEL) (center); the Oriented Scintillation Spectrometer Experiment (OSSE) (top); and Burst and Transient Source Experiment (BATSE) (on four corners). The view was taken by STS-37 crew through an aft flight deck overhead window.

  5. STS-56 remote manipulator system (RMS) backdropped against Aurora Borealis

    NASA Technical Reports Server (NTRS)

    1993-01-01

    STS-56 remote manipulator system (RMS) arm is backdropped against the 'northern lights' (Aurora Borealis) in this view exposed from the crew cabin of Discovery, Orbiter Vehicle (OV) 103. The arm was used in operations with the Shuttle Pointed Autonomous Research Tool for Astronomy 201 (SPARTAN-201). Space Shuttle astronauts have the opportunity to observe auroral activity only on 57-degree inclination missions and only in the 'night' hemisphere. Astronaut hand-held photography is the only method which is capable of documenting the detailed structure of the auroral oval.

  6. STS-37 Gamma Ray Observatory (GRO) grappled by RMS

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Backdropped against the Earth's surface, the Gamma Ray Observatory (GRO) with its solar array (SA) panels deployed is grappled by the remote manipulator system (RMS) during STS-37 systems checkout. GRO's four complement instruments are visible: the Energetic Gamma Ray Experiment Telescope (EGRET) (at the bottom); the Imaging Compton Telescope (COMPTEL) (center); the Oriented Scintillation Spectrometer Experiment (OSSE) (top); and Burst and Transient Source Experiment (BATSE) (on four corners). The view was taken by STS-37 crew through an aft flight deck overhead window.

  7. RMS Titanic and the emergence of new concepts on consortial nature of microbial events.

    PubMed

    Cullimore, D Roy; Pellegrino, Charles; Johnston, Lori

    2002-01-01

    The RMS Titanic sank in 1912 and created a historical event that still ripples through time. Stories were told and lessons learned but the science has only just begun. Today the fading remains of the ship resemble the hanging gardens of Babylon except that it is not plants that drape the walls but complex microbial growths called rusticles. These organisms have been found to be not a species, like plants and animals, but to be structures created by complex communities of bacterial species. Like the discovery of tube worms in the mid-oceanic vents, the nature of these rusticles presents another biological discovery of a fundamental nature. Essentially these microbial consortia on the RMS Titanic have generated structures of a mass that would rival whales and elephants while gradually extracting the iron from the steel. Rusticle-like consortia appear to play many roles within the environment, and it is perhaps the RMS Titanic that is showing that there is a new way to understand the form, function, and nature of microorganisms. This understanding would develop by considering the bacteria not as individual species functioning independently but as consortia of species functioning in community structures within a common habitat. This concept, if adopted, would change dramatically the manner in which a microbial ecologist and any scientist or engineer would view the occurrence of a slime, encrustation, biocolloid, rust flake, iron pan, salt deposit, and perhaps even some of the diseases that remain unexplained as a disease of unknown cause.

  8. Large area spark counter with fine time and position resolution

    SciTech Connect

    Ogawa, A.; Fujiwara, N.; Pestov, Yu.N.; Sugahara, R.

    1984-03-01

    The key properties of spark counters include their capability of precision timing (at the sub 100 ps level) and of measuring the position of the charged particle to high accuracy. At SLAC we have undertaken a program to develop these devices for use in high energy physics experiments involving large detectors. A spark counter of size 1.2 m x 0.1 m has been constructed and has been operating continuously in our test setup for several months. Some details of its construction and its properties as a particle detector are reported. 14 references. (WHK)

  9. High Time Resolution Studies of Binary X-Ray Pulsars

    NASA Astrophysics Data System (ADS)

    Cominsky, Lynn R.

    1996-05-01

    The work for this project was substantially more than anticipated, and involved recreating an analysis system for all the HEAO A-1 scanning data which had been converted to the ELE format. As a result of this work, a complete software analysis package was first created at Sonoma State University using Fortran, that can extract the data for any given X-ray source, and produce light curves from the scanning data. A second complete software analysis package was also created, this time in IDL, which can also display all the data in a timely manner, allowing data screening without the generation of hardcopy plots. The creation of the software systems was not the original goal of the project; rather this was a necessary result when the NRL computers became inoperable due to old age and could not be used to support the project, as originally planned. There were 6 sources originally proposed for analysis: SMC X-1, A0538-66, LMC X-1, LMC X-3, (these 3 sources are all located in the Large Magellanic Cloud region), 4UO115+63 and 4U1626-67. Results on these sources are summarized.

  10. Time resolution of time-of-flight detector based on multiple scintillation counters readout by SiPMs

    NASA Astrophysics Data System (ADS)

    Cattaneo, P. W.; De Gerone, M.; Gatti, F.; Nishimura, M.; Ootani, W.; Rossella, M.; Shirabe, S.; Uchiyama, Y.

    2016-08-01

    A new timing detector measuring ∼ 50 MeV / c positrons is under development for the MEG II experiment, aiming at a time resolution σt ∼ 30 ps. The resolution is expected to be achieved by measuring each positron time with multiple counters made of plastic scintillator readout by silicon photomultipliers (SiPMs). The purpose of this work is to demonstrate the time resolution for ∼ 50 MeV / c positrons using prototype counters. Counters with dimensions of 90 × 40 × 5mm3 readout by six SiPMs (three on each 40 × 5mm2 plane) were built with SiPMs from Hamamatsu Photonics and AdvanSiD and tested in a positron beam at the DAΦNE Beam Test Facility. The time resolution was found to improve nearly as the square root of the number of counter hits. A time resolution σt = 26.2 ± 1.3 ps was obtained with eight counters with Hamamatsu SiPMs. These results suggest that the design resolution is achievable in the MEG II experiment.

  11. Large area spark counters with fine time and position resolution

    SciTech Connect

    Ogawa, A.; Atwood, W.B.; Fujiwara, N.; Pestov, Yu.N.; Sugahara, R.

    1983-10-01

    Spark counters trace their history back over three decades but have been used in only a limited number of experiments. The key properties of these devices include their capability of precision timing (at the sub 100 ps level) and of measuring the position of the charged particle to high accuracy. At SLAC we have undertaken a program to develop these devices for use in high energy physics experiments involving large detectors. A spark counter of size 1.2 m x 0.1 m has been constructed and has been operating continuously in our test setup for several months. In this talk I will discuss some details of its construction and its properties as a particle detector. 14 references.

  12. Real-time super-resolution imaging by high-speed fluorescence emission difference microscopy

    NASA Astrophysics Data System (ADS)

    Rong, Zihao; Li, Shuai; Kuang, Cuifang; Xu, Yingke; Liu, Xu

    2014-09-01

    The recently proposed fluorescence emission difference (FED) microscopy has been demonstrated to be capable of breaking the diffraction barrier, which restricts the spatial resolution of far-field fluorescence microscopy. In this paper, we report a novel high-speed FED system that can realize real-time super-resolution imaging. By replacing the conventional nanopositioning stage with a galvo mirror, the temporal resolution of FED is improved to nearly one frame per second, which is 100 times faster than that of best existing FED, while the system maintains a super-high spatial resolution of 150 nm, which is far beyond the diffraction barrier. Therefore, the high-speed FED is suitable for large-area observations while avoiding photobleaching. Detailed theoretical analysis, simulations, and experimental real-time resolution tests on 100 nm nanoparticles and biological cells are reported.

  13. Fluoro Jade-B detection of dying cells in the SVZ and RMS of adult rats after bilateral olfactory bulbectomy.

    PubMed

    Mitrusková, Barbora; Orendácová, Judita; Raceková, Enikö

    2005-12-01

    A novel fluorochrome, Fluoro-Jade B, was used to detect dying precursor cells in the subventricular zone (SVZ) and rostral migratory stream (RMS) of adult rats after bilateral olfactory bulbectomy and in control intact rats. The animals in experimental group were left to survive 3 days and from 3 till 16 months after surgical procedure. 1. In the control animals, Fluoro-Jade B positive cells were visible in the SVZ and within the whole extent of the RMS. The number of Fluoro-Jade B positive cells increased in the elbow in comparison to the rest parts of the RMS. 2. In the experimental animals surviving either 3 days or from 3 till 16 months after bilateral olfactory bulbectomy, Fluoro-Jade B positive cells displayed the similar pattern of distribution as in the control animals. However, some quantitative differences in the labeled cells number along the rostral migratory pathway appeared. 3. The average number of degenerating cells within the control SVZ and RMS was 26.24+/- 0.686. In bulbectomized animals, regardless of survival time, an insignificant increase of Fluoro-Jade B positive cells number occurred. We can conclude that dying of precursor cells is a physiological process running within the SVZ/RMS in both control and experimental animals. Moreover, this physiological process is not influenced by survival period after bilateral olfactory bulbectomy. Our results demonstrate Fluoro-Jade B as a useful marker of dying cells.

  14. Reaching time resolution of less than 10 ps with plastic scintillation detectors

    NASA Astrophysics Data System (ADS)

    Zhao, J. W.; Sun, B. H.; Tanihata, I.; Terashima, S.; Zhu, L. H.; Enomoto, A.; Nagae, D.; Nishimura, T.; Omika, S.; Ozawa, A.; Takeuchi, Y.; Yamaguchi, T.

    2016-07-01

    Timing-pick up detectors with excellent timing resolutions are essential in many modern nuclear physics experiments. Aiming to develop a Time-Of-Flight system with precision down to about 10 ps, we have made a systematic study of the timing characteristic of TOF detectors, which consist of several combinations of plastic scintillators and photomultiplier tubes. With the conventional electronics, the best timing resolution of about 5.1 ps (σ) has been achieved for detectors with an area size of 3 × 1cm2 . It is found that for data digitalization a combination of TAC and ADC can achieve a better time resolution than the currently available TDC. Simultaneous measurements of both time and pulse height are very valuable for the correction of time-walk effect.

  15. Simulation of shuttle flight control system structural interaction with RMS deployed payloads

    NASA Technical Reports Server (NTRS)

    Turnball, Joe

    1989-01-01

    A simulation of the system made up of the Orbiter, Remote Manipulator System (RMS), and payload grappled by the RMS was completed. The simulation was used to study the stability of this overall system when its attitude is under control of the Orbiter's on-orbit Flight Control System (FCS). The simulation was also used to study the dynamics of the system when the RMS and its associated command software are in active control of the relative Orbiter to payload position and orientation. The simulation models all of the following elements: RMS boom bending (represented by two cubic bending models); RMS boom torsion; RMS joint gearbox compliance (represented by a non-linear wind-up model); flexibility at the RMS to Orbiter interface; flexibility at the RMS to payload interface; joint motor dynamics; joint servo-loop dynamics; RMS on-board computer command logic; data transfer delays between the RMS sensor and the RMS on-board computer and between the RMS on-board computer and RMS joint servos; on-orbit flight control nonlinear control logic; and the Reaction Control System (both Primary and Vernier) jet forces and moments.

  16. A Semiquantitative Framework for Gene Regulatory Networks: Increasing the Time and Quantitative Resolution of Boolean Networks

    PubMed Central

    Kerkhofs, Johan; Geris, Liesbet

    2015-01-01

    Boolean models have been instrumental in predicting general features of gene networks and more recently also as explorative tools in specific biological applications. In this study we introduce a basic quantitative and a limited time resolution to a discrete (Boolean) framework. Quantitative resolution is improved through the employ of normalized variables in unison with an additive approach. Increased time resolution stems from the introduction of two distinct priority classes. Through the implementation of a previously published chondrocyte network and T helper cell network, we show that this addition of quantitative and time resolution broadens the scope of biological behaviour that can be captured by the models. Specifically, the quantitative resolution readily allows models to discern qualitative differences in dosage response to growth factors. The limited time resolution, in turn, can influence the reachability of attractors, delineating the likely long term system behaviour. Importantly, the information required for implementation of these features, such as the nature of an interaction, is typically obtainable from the literature. Nonetheless, a trade-off is always present between additional computational cost of this approach and the likelihood of extending the model’s scope. Indeed, in some cases the inclusion of these features does not yield additional insight. This framework, incorporating increased and readily available time and semi-quantitative resolution, can help in substantiating the litmus test of dynamics for gene networks, firstly by excluding unlikely dynamics and secondly by refining falsifiable predictions on qualitative behaviour. PMID:26067297

  17. A Semiquantitative Framework for Gene Regulatory Networks: Increasing the Time and Quantitative Resolution of Boolean Networks.

    PubMed

    Kerkhofs, Johan; Geris, Liesbet

    2015-01-01

    Boolean models have been instrumental in predicting general features of gene networks and more recently also as explorative tools in specific biological applications. In this study we introduce a basic quantitative and a limited time resolution to a discrete (Boolean) framework. Quantitative resolution is improved through the employ of normalized variables in unison with an additive approach. Increased time resolution stems from the introduction of two distinct priority classes. Through the implementation of a previously published chondrocyte network and T helper cell network, we show that this addition of quantitative and time resolution broadens the scope of biological behaviour that can be captured by the models. Specifically, the quantitative resolution readily allows models to discern qualitative differences in dosage response to growth factors. The limited time resolution, in turn, can influence the reachability of attractors, delineating the likely long term system behaviour. Importantly, the information required for implementation of these features, such as the nature of an interaction, is typically obtainable from the literature. Nonetheless, a trade-off is always present between additional computational cost of this approach and the likelihood of extending the model's scope. Indeed, in some cases the inclusion of these features does not yield additional insight. This framework, incorporating increased and readily available time and semi-quantitative resolution, can help in substantiating the litmus test of dynamics for gene networks, firstly by excluding unlikely dynamics and secondly by refining falsifiable predictions on qualitative behaviour. PMID:26067297

  18. RMS upper boom framed by aft flight deck viewing window W10

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Remote Manipulator System (RMS) upper arm boom (tear in multilayer beta cloth) deployed during dynamic interaction test using Payload Flight Test Article (PFTA) is visible outside aft viewing window W10. RMS 'Canada' insignia or logo appears on boom.

  19. Test and characterisation of SiPMs for the MEGII high resolution Timing Counter

    NASA Astrophysics Data System (ADS)

    Simonetta, M.; Biasotti, M.; Boca, G.; Cattaneo, P. W.; De Gerone, M.; Gatti, F.; Nardò, R.; Nishimura, M.; Ootani, W.; Pizzigoni, G.; Prata, M. C.; Rossella, M.; Shibata, N.; Uchiyama, Y.; Yoshida, K.

    2016-07-01

    The MEGII Timing Counter will measure the positron time of arrival with a resolution of ~ 30 ps relying on two arrays of scintillator pixels read out by 6144 Silicon Photomultipliers (SiPMs) from AdvanSiD. They are characterised, measuring their breakdown voltage, to assure that the gains of the SiPMs of each pixel are as uniform as possible, to maximise the pixel resolution. Gain measurements have also been performed.

  20. Post-processing method to reduce noise while preserving high time resolution in aethalometer real-time black carbon data

    EPA Science Inventory

    Real-time aerosol black carbon (BC) data, presented at time resolutions on the order of seconds to minutes, is desirable in field and source characterization studies measuring rapidly varying concentrations of BC. The Optimized Noise-reduction Averaging (ONA) algorithm has been d...

  1. Efficient Solar Scene Wavefront Estimation with Reduced Systematic and RMS Errors: Summary

    NASA Astrophysics Data System (ADS)

    Anugu, N.; Garcia, P.

    2016-04-01

    computational efficiency. In the first step, the cross-correlation is implemented at the original image spatial resolution grid (1 pixel). In the second step, the cross-correlation is performed using a sub-pixel level grid by limiting the field of search to 4 × 4 pixels centered at the first step delivered initial position. The generation of these sub-pixel grid based region of interest images is achieved with the bi-cubic interpolation. The correlation matching with sub-pixel grid technique was previously reported in electronic speckle photography Sjö'dahl (1994). This technique is applied here for the solar wavefront sensing. A large dynamic range and a better accuracy in the measurements are achieved with the combination of the original pixel grid based correlation matching in a large field of view and a sub-pixel interpolated image grid based correlation matching within a small field of view. The results revealed that the proposed method outperforms all the different peak-finding algorithms studied in the first approach. It reduces both the systematic error and the RMS error by a factor of 5 (i.e., 75% systematic error reduction), when 5 times improved image sampling was used. This measurement is achieved at the expense of twice the computational cost. With the 5 times improved image sampling, the wave front accuracy is increased by a factor of 5. The proposed solution is strongly recommended for wave front sensing in the solar telescopes, particularly, for measuring large dynamic image shifts involved open loop adaptive optics. Also, by choosing an appropriate increment of image sampling in trade-off between the computational speed limitation and the aimed sub-pixel image shift accuracy, it can be employed in closed loop adaptive optics. The study is extended to three other class of sub-aperture images (a point source; a laser guide star; a Galactic Center extended scene). The results are planned to submit for the Optical Express journal.

  2. a Decade-Spanning High-Resolution Asynchronous Optical Sampling Based Terahertz Time-Domain Spectrometer

    NASA Astrophysics Data System (ADS)

    Good, Jacob T.; Holland, Daniel; Finneran, Ian A.; Carroll, Brandon; Allodi, Marco A.; Blake, Geoffrey

    2015-06-01

    High-resolution ASynchronous OPtical Sampling (ASOPS) is a technique that substantially improves the combined frequency resolution and bandwidth of ASOPS based TeraHertz Time-Domain Spectroscopy (THz-TDS) systems. We employ two mode-locked femtosecond Ti:Sapphire oscillators with repetition frequencies of 80 MHz operating at a fixed repetition frequency offset of 100 Hz. This offset lock is maintained by a Phase-Locked Loop (PLL) operating at the 60th harmonic of the repetition rate of the Ti:Sapphire oscillators. Their respective time delay is scanned across 12.5 ns requiring a scan time of 10 ms, supporting a time delay resolution of up to 15.6 fs. ASOPS-THz-TDS enables high-resolution spectroscopy that is impossible for a THz-TDS system employing a mechanical delay stage. We measure a timing jitter of 1.36 fs for the system using an air-gap etalon and an optical cross-correlator. We report a Root-Mean-Square deviation of 20.7 MHz and a mean deviation of 14.4 MHz for water absorption lines from 0.5 to 2.7. High-resolution ASOPS-THz-TDS enables high resolution spectroscopy of both gas-phase and condensed-phase samples across a decade of THz bandwidth.

  3. A demonstration of ultra-high time resolution with a pulse-dilation photo-multiplier

    NASA Astrophysics Data System (ADS)

    Hares, J. D.; Dymoke-Bradshaw, A. K. L.; Hilsabeck, T. J.; Kilkenny, J. D.; Morris, D.; Horsfield, C. J.; Gales, S. G.; Milnes, J.; Herrmann, H. W.; McFee, C.

    2016-05-01

    A novel microchannel plate (MCP) intensified high-speed photo-multiplier tube making use of pulse-dilation[1] has been tested. A ramped photo-cathode voltage followed by a relatively long drift region results in a transit time which is dependent on the photo-electron birth time. This leads to temporal magnification or dilation, so providing an enhancement in time resolution of the optical signal with respect to the electrical signal at the output anode. By this means a time resolution on the order of picoseconds may be realized with a substantially slower oscilloscope. The photo-electron signal is guided from a photo-cathode to an MCP by an axial magnetic field and a short input record length is stretched by a factor up to 40X to yield significantly improved time resolution at the photo-cathode. Results of the first measurements are presented.

  4. Design and performance of a high spatial resolution, time-of-flight PET detector

    PubMed Central

    Krishnamoorthy, Srilalan; LeGeyt, Benjamin; Werner, Matthew E.; Kaul, Madhuri; Newcomer, F. M.; Karp, Joel S.; Surti, Suleman

    2014-01-01

    This paper describes the design and performance of a high spatial resolution PET detector with time-of-flight capabilities. With an emphasis on high spatial resolution and sensitivity, we initially evaluated the performance of several 1.5 × 1.5 and 2.0 × 2.0 mm2 and 12–15 mm long LYSO crystals read out by several appropriately sized PMTs. Experiments to evaluate the impact of reflector on detector performance were performed and the final detector consisted of a 32 × 32 array of 1.5 × 1.5 × 15 mm3 LYSO crystals packed with a diffuse reflector and read out by a single Hamamatsu 64 channel multi-anode PMT. Such a design made it compact, modular and offered a cost-effective solution to obtaining excellent energy and timing resolution. To minimize the number of readout signals, a compact front-end readout electronics that summed anode signals along each of the orthogonal directions was also developed. Experimental evaluation of detector performance demonstrates clear discrimination of the crystals within the detector. An average energy resolution (FWHM) of 12.7 ± 2.6% and average coincidence timing resolution (FWHM) of 348 ps was measured, demonstrating suitability for use in the development of a high spatial resolution time-of-flight scanner for dedicated breast PET imaging. PMID:25246711

  5. Time-Resolved High-Spatial-Resolution Measurements of Underwater Laser Ionization and Filamentation

    NASA Astrophysics Data System (ADS)

    Jones, T. G.; Kaganovich, D.; Helle, M. H.; Penano, J.; Ting, A.; Gordon, D.

    2013-10-01

    Laser triggering and guiding of underwater electrical discharges are being investigated and developed at NRL for applications including advanced micromachining and low-frequency laser acoustic generation. As part of this development we recently made several high-spatial-resolution, time-resolved measurements of underwater optical filamentation and laser ionization. Using 2-laser pump-probe backlit imaging techniques, we were able to achieve time resolution as short as 35 fs and spatial resolution down to 1 micron. Shadowgraph images show few-micron diameter gas bubbles forming throughout the pump beam path in ps timescales. Microbubble numbers and density increased with pulse energy and time during the pump pulse. We also obtained time-resolved spectra of ns-laser-ionized water, revealing black-body radiation lasting more than 100 ns after the ionizing pulse. Results from ongoing underwater laser ionization, filamentation, and discharge-guiding experiments will be presented. This work is supported by NRL Base Funds.

  6. Multigap RPC time resolution to 511 keV annihilation photons

    NASA Astrophysics Data System (ADS)

    Belli, G.; Gabusi, M.; Musitelli, G.; Nardò, R.; Ratti, S. P.; Tamborini, A.; Vitulo, P.

    2015-05-01

    The time resolution of Multigap Resistive Plate Chambers (MRPCs) to 511 keV gamma rays has been investigated using a 22Na source and four detectors. The MRPCs time resolution has been derived from the Time-of-Flight information, measured from pairs of space correlated triggered events. A GEANT4 simulation has been performed to analyze possible setup contributions and to support experimental results. A time resolution (FWHM) of 312 ps and 376 ps has been measured for a single MRPC with four 250 μm gas gaps by considering respectively one and two independent pairs of detectors. These values, endorsed by the GEANT4 simulation, represent a good result compared to those reported in the literature.

  7. Measurements of timing resolution of ultra-fast silicon detectors with the SAMPIC waveform digitizer

    NASA Astrophysics Data System (ADS)

    Breton, D.; De Cacqueray, V.; Delagnes, E.; Grabas, H.; Maalmi, J.; Minafra, N.; Royon, C.; Saimpert, M.

    2016-11-01

    The SAMpler for PICosecond time (SAMPIC) chip has been designed by a collaboration including CEA/IRFU/SEDI, Saclay and CNRS/LAL/SERDI, Orsay. It benefits from both the quick response of a time to digital converter and the versatility of a waveform digitizer to perform accurate timing measurements. Thanks to the sampled signals, smart algorithms making best use of the pulse shape can be used to improve time resolution. A software framework has been developed to analyse the SAMPIC output data and extract timing information by using either a constant fraction discriminator or a fast cross-correlation algorithm. SAMPIC timing capabilities together with the software framework have been tested using pulses generated by a signal generator or by a silicon detector illuminated by a pulsed infrared laser. Under these ideal experimental conditions, the SAMPIC chip has proven to be capable of timing resolutions down to 4 ps with synthesized signals and 40 ps with silicon detector signals.

  8. High-speed asynchronous optical sampling with sub-50fs time resolution.

    PubMed

    Gebs, R; Klatt, G; Janke, C; Dekorsy, T; Bartels, A

    2010-03-15

    We report an ultrafast time-domain spectroscopy system based on high-speed asynchronous optical sampling operating without mechanical scanner. The system uses two 1 GHz femtosecond oscillators that are offset-stabilized using high-bandwidth feedback electronics operating at the tenth repetition rate harmonics. Definition of the offset frequency, i.e. the time-delay scan rate, in the range of a few kilohertz is accomplished using direct-digital-synthesis electronics for the first time. The time-resolution of the system over the full available 1 ns time-delay window is determined by the laser pulse duration and is 45 fs. This represents a three-fold improvement compared to previous approaches where timing jitter was the limiting factor. Two showcase experiments are presented to verify the high time-resolution and sensitivity of the system.

  9. Measurement of Time Resolution of the Mu2e LYSO Calorimeter Prototype

    SciTech Connect

    Atanov, N.

    2015-09-16

    In this paper we present the time resolution measurements of the LutetiumYttrium Oxyorthosilicate (LYSO) calorimeter prototype for the Mu2e experiment. The measurements have been performed using the e- beam of the Beam Test Facility (BTF) in Frascati, Italy in the energy range from 100 to 400 MeV. The calorimeter prototype consisted of twenty five 30x30x130 mm3, LYSO crystals read out by 10x10 mm2 Hamamatsu Avalanche Photodiodes (APDs). The energy dependence of the measured time resolution can be parametrized as σt(E) = a/pE/GeV⊕b, with the stochastic and constant terms a = (51±1) ps and b = (14 ± 1) ps, respectively. This corresponds to the time resolution of (162 ± 3) ps at 100 MeV.

  10. Achievable spatial resolution of time-resolved transillumination imaging systems which utilize multiply scattered light

    NASA Astrophysics Data System (ADS)

    Moon, J. A.; Battle, P. R.; Bashkansky, M.; Mahon, R.; Duncan, M. D.; Reintjes, J.

    1996-01-01

    We describe theoretically and measure experimentally the best achievable time-dependent point-spread-function of light in the presence of strong turbidity. We employ the rescaled isotropic-scattering solution to the time-dependent radiative transfer equation to examine three mathematically distinct limits of photonic transport: the ballistic, quasidiffuse, and diffuse limits. In all cases we follow the constraint that a minimum fractional number of launched photons must be received before the time-integrating detector is turned off. We show how the achievable ballistic resolution maps into the diffusion-limited achievable resolution, and verify this behavior experimentally by using a coherently amplified Raman polarization gate imaging system. We are able to quantitatively fit the measured best achievable resolution by empirically rescaling the scattering length in the model.

  11. High resolution time of arrival estimation for a cooperative sensor system

    NASA Astrophysics Data System (ADS)

    Morhart, C.; Biebl, E. M.

    2010-09-01

    Distance resolution of cooperative sensors is limited by the signal bandwidth. For the transmission mainly lower frequency bands are used which are more narrowband than classical radar frequencies. To compensate this resolution problem the combination of a pseudo-noise coded pulse compression system with superresolution time of arrival estimation is proposed. Coded pulsecompression allows secure and fast distance measurement in multi-user scenarios which can easily be adapted for data transmission purposes (Morhart and Biebl, 2009). Due to the lack of available signal bandwidth the measurement accuracy degrades especially in multipath scenarios. Superresolution time of arrival algorithms can improve this behaviour by estimating the channel impulse response out of a band-limited channel view. For the given test system the implementation of a MUSIC algorithm permitted a two times better distance resolution as the standard pulse compression.

  12. Acoustic resolution photoacoustic Doppler velocity measurements in fluids using time-domain cross-correlation

    NASA Astrophysics Data System (ADS)

    Brunker, J.; Beard, P.

    2013-03-01

    Blood flow measurements have been demonstrated using the acoustic resolution mode of photoacoustic sensing. This is unlike previous flowmetry methods using the optical resolution mode, which limits the maximum penetration depth to approximately 1mm. Here we describe a pulsed time correlation photoacoustic Doppler technique that is inherently flexible, lending itself to both resolution modes. Doppler time shifts are quantified via cross-correlation of pairs of photoacoustic waveforms generated in moving absorbers using pairs of laser light pulses, and the photoacoustic waves detected using an ultrasound transducer. The acoustic resolution mode is employed by using the transducer focal width, rather than the large illuminated volume, to define the lateral spatial resolution. The use of short laser pulses allows depth-resolved measurements to be obtained with high spatial resolution, offering the prospect of mapping flow within microcirculation. Whilst our previous work has been limited to a non-fluid phantom, we now demonstrate measurements in more realistic blood-mimicking phantoms incorporating fluid suspensions of microspheres flowing along an optically transparent tube. Velocities up to 110 mm/s were measured with accuracies approaching 1% of the known velocities, and resolutions of a few mm/s. The velocity range and resolution are scalable with excitation pulse separation, but the maximum measurable velocity was considerably smaller than the value expected from the detector focal beam width. Measurements were also made for blood flowing at velocities up to 13.5 mm/s. This was for a sample reduced to 5% of the normal haematocrit; increasing the red blood cell concentration limited the maximum measurable velocity so that no results were obtained for concentrations greater than 20% of a physiologically realistic haematocrit. There are several possible causes for this limitation; these include the detector bandwidth and irregularities in the flow pattern. Better

  13. A high time resolution x-ray diagnostic on the Madison Symmetric Torus

    NASA Astrophysics Data System (ADS)

    DuBois, Ami M.; Lee, John David; Almagri, Abdulgadar F.

    2015-07-01

    A new high time resolution x-ray detector has been installed on the Madison Symmetric Torus (MST) to make measurements around sawtooth events. The detector system is comprised of a silicon avalanche photodiode, a 20 ns Gaussian shaping amplifier, and a 500 MHz digitizer with 14-bit sampling resolution. The fast shaping time diminishes the need to restrict the amount of x-ray flux reaching the detector, limiting the system dead-time. With a much higher time resolution than systems currently in use in high temperature plasma physics experiments, this new detector has the versatility to be used in a variety of discharges with varying flux and the ability to study dynamics on both slow and fast time scales. This paper discusses the new fast x-ray detector recently installed on MST and the improved time resolution capabilities compared to the existing soft and hard x-ray diagnostics. In addition to the detector hardware, improvements to the detector calibration and x-ray pulse identification software, such as additional fitting parameters and a more sophisticated fitting routine are discussed. Finally, initial data taken in both high confinement and standard reversed-field pinch plasma discharges are compared.

  14. Time-resolved serial crystallography captures high-resolution intermediates of photoactive yellow protein

    SciTech Connect

    Tenboer, Jason; Basu, Shibom; Zatsepin, Nadia; Pande, Kanupriya; Milathianaki, Despina; Frank, Matthias; Hunter, Mark; Boutet, Sebastien; Williams, Garth J.; Koglin, Jason E.; Oberthuer, Dominik; Heymann, Michael; Kupitz, Christopher; Conrad, Chelsie; Coe, Jesse; Roy-Chowdhury, Shatabdi; Weierstall, Uwe; James, Daniel; Wang, Dingjie; Grant, Thomas; Barty, Anton; Yefanov, Oleksandr; Scales, Jennifer; Gati, Cornelius; Seuring, Carolin; Srajer, Vukica; Henning, Robert; Schwander, Peter; Fromme, Raimund; Ourmazd, Abbas; Moffat, Keith; Van Thor, Jasper J.; Spence, John C. H.; Fromme, Petra; Chapman, Henry N.; Schmidt, Marius

    2014-12-05

    We report that serial femtosecond crystallography using ultrashort pulses from X-ray Free Electron Lasers (XFELs) offers the possibility to study light-triggered dynamics of biomolecules. Using microcrystals of the blue light photoreceptor, photoactive yellow protein, as a model system, we present high resolution, time-resolved difference electron density maps of excellent quality with strong features, which allow the determination of structures of reaction intermediates to 1.6 Å resolution. These results open the way to the study of reversible and non-reversible biological reactions on time scales as short as femtoseconds under conditions which maximize the extent of reaction initiation throughout the crystal.

  15. Real-time analysis and visualization for single-molecule based super-resolution microscopy.

    PubMed

    Kechkar, Adel; Nair, Deepak; Heilemann, Mike; Choquet, Daniel; Sibarita, Jean-Baptiste

    2013-01-01

    Accurate multidimensional localization of isolated fluorescent emitters is a time consuming process in single-molecule based super-resolution microscopy. We demonstrate a functional method for real-time reconstruction with automatic feedback control, without compromising the localization accuracy. Compatible with high frame rates of EM-CCD cameras, it relies on a wavelet segmentation algorithm, together with a mix of CPU/GPU implementation. A combination with Gaussian fitting allows direct access to 3D localization. Automatic feedback control ensures optimal molecule density throughout the acquisition process. With this method, we significantly improve the efficiency and feasibility of localization-based super-resolution microscopy.

  16. Characteristics of electricity generation with intermittent sources depending on the time resolution of the input data

    NASA Astrophysics Data System (ADS)

    Wagner, F.; Wertz, F.

    2016-08-01

    Data on the electricity supply with intermittent renewable sources are made public by the Transmission System Operators (TSO) and other sources. Data are typically provided in 1h increments. In this paper, we analyse wind and photo-voltaic data from the Czech Republic. The analysis concentrates on major characteristics of a supply situation where the annual demand is formally met by scaled-up wind and photovoltaic power. The original data are supplied in 1min increments and successively averaged up to 1h time resolution. This paper focuses on the dependence of the major supply characteristics on the time resolution of the available electricity data.

  17. Time-Resolved Serial Crystallography Captures High Resolution Intermediates of Photoactive Yellow Protein

    PubMed Central

    Tenboer, Jason; Basu, Shibom; Zatsepin, Nadia; Pande, Kanupria; Milathianaki, Despina; Frank, Matthias; Hunter, Mark; Boutet, Sébastien; Williams, Garth J.; Koglin, Jason E.; Oberthuer, Dominik; Heymann, Michael; Kupitz, Christopher; Conrad, Chelsie; Coe, Jesse; Roy-Chowdhury, Shatabdi; Weierstall, Uwe; James, Daniel; Wang, Dingjie; Grant, Thomas; Barty, Anton; Yefanov, Oleksandr; Scales, Jennifer; Gati, Cornelius; Seuring, Carolin; Srajer, Vukica; Henning, Robert; Schwander, Peter; Fromme, Raimund; Ourmazd, Abbas; Moffat, Keith; Van Thor, Jasper; Spence, John H. C.; Fromme, Petra; Chapman, Henry N.; Schmidt, Marius

    2015-01-01

    Serial femtosecond crystallography using ultrashort pulses from X-ray Free Electron Lasers (XFELs) offers the possibility to study light-triggered dynamics of biomolecules. Using microcrystals of the blue light photoreceptor, photoactive yellow protein, as a model system, we present high resolution, time-resolved difference electron density maps of excellent quality with strong features, which allow the determination of structures of reaction intermediates to 1.6 Å resolution. These results open the way to the study of reversible and non-reversible biological reactions on time scales as short as femtoseconds under conditions which maximize the extent of reaction initiation throughout the crystal. PMID:25477465

  18. Time-resolved serial crystallography captures high-resolution intermediates of photoactive yellow protein.

    PubMed

    Tenboer, Jason; Basu, Shibom; Zatsepin, Nadia; Pande, Kanupriya; Milathianaki, Despina; Frank, Matthias; Hunter, Mark; Boutet, Sébastien; Williams, Garth J; Koglin, Jason E; Oberthuer, Dominik; Heymann, Michael; Kupitz, Christopher; Conrad, Chelsie; Coe, Jesse; Roy-Chowdhury, Shatabdi; Weierstall, Uwe; James, Daniel; Wang, Dingjie; Grant, Thomas; Barty, Anton; Yefanov, Oleksandr; Scales, Jennifer; Gati, Cornelius; Seuring, Carolin; Srajer, Vukica; Henning, Robert; Schwander, Peter; Fromme, Raimund; Ourmazd, Abbas; Moffat, Keith; Van Thor, Jasper J; Spence, John C H; Fromme, Petra; Chapman, Henry N; Schmidt, Marius

    2014-12-01

    Serial femtosecond crystallography using ultrashort pulses from x-ray free electron lasers (XFELs) enables studies of the light-triggered dynamics of biomolecules. We used microcrystals of photoactive yellow protein (a bacterial blue light photoreceptor) as a model system and obtained high-resolution, time-resolved difference electron density maps of excellent quality with strong features; these allowed the determination of structures of reaction intermediates to a resolution of 1.6 angstroms. Our results open the way to the study of reversible and nonreversible biological reactions on time scales as short as femtoseconds under conditions that maximize the extent of reaction initiation throughout the crystal.

  19. Time-resolved serial crystallography captures high-resolution intermediates of photoactive yellow protein.

    PubMed

    Tenboer, Jason; Basu, Shibom; Zatsepin, Nadia; Pande, Kanupriya; Milathianaki, Despina; Frank, Matthias; Hunter, Mark; Boutet, Sébastien; Williams, Garth J; Koglin, Jason E; Oberthuer, Dominik; Heymann, Michael; Kupitz, Christopher; Conrad, Chelsie; Coe, Jesse; Roy-Chowdhury, Shatabdi; Weierstall, Uwe; James, Daniel; Wang, Dingjie; Grant, Thomas; Barty, Anton; Yefanov, Oleksandr; Scales, Jennifer; Gati, Cornelius; Seuring, Carolin; Srajer, Vukica; Henning, Robert; Schwander, Peter; Fromme, Raimund; Ourmazd, Abbas; Moffat, Keith; Van Thor, Jasper J; Spence, John C H; Fromme, Petra; Chapman, Henry N; Schmidt, Marius

    2014-12-01

    Serial femtosecond crystallography using ultrashort pulses from x-ray free electron lasers (XFELs) enables studies of the light-triggered dynamics of biomolecules. We used microcrystals of photoactive yellow protein (a bacterial blue light photoreceptor) as a model system and obtained high-resolution, time-resolved difference electron density maps of excellent quality with strong features; these allowed the determination of structures of reaction intermediates to a resolution of 1.6 angstroms. Our results open the way to the study of reversible and nonreversible biological reactions on time scales as short as femtoseconds under conditions that maximize the extent of reaction initiation throughout the crystal. PMID:25477465

  20. 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.

  1. Real-time high-resolution heterodyne-based measurements of spectral dynamics in fibre lasers

    PubMed Central

    Sugavanam, Srikanth; Fabbri, Simon; Le, Son Thai; Lobach, Ivan; Kablukov, Sergey; Khorev, Serge; Churkin, Dmitry

    2016-01-01

    Conventional tools for measurement of laser spectra (e.g. optical spectrum analysers) capture data averaged over a considerable time period. However, the generation spectrum of many laser types may involve spectral dynamics whose relatively fast time scale is determined by their cavity round trip period, calling for instrumentation featuring both high temporal and spectral resolution. Such real-time spectral characterisation becomes particularly challenging if the laser pulses are long, or they have continuous or quasi-continuous wave radiation components. Here we combine optical heterodyning with a technique of spatio-temporal intensity measurements that allows the characterisation of such complex sources. Fast, round-trip-resolved spectral dynamics of cavity-based systems in real-time are obtained, with temporal resolution of one cavity round trip and frequency resolution defined by its inverse (85 ns and 24 MHz respectively are demonstrated). We also show how under certain conditions for quasi-continuous wave sources, the spectral resolution could be further increased by a factor of 100 by direct extraction of phase information from the heterodyned dynamics or by using double time scales within the spectrogram approach. PMID:26984634

  2. In vivo dynamic process imaging using real-time optical-resolution photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Shi, Wei; Shao, Peng; Hajireza, Parsin; Forbrich, Alexander; Zemp, Roger J.

    2013-02-01

    The authors demonstrate in vivo dynamic process imaging using a label-free real-time optical-resolution photoacoustic microscope (OR-PAM). This reflection-mode system takes advantage of a 532-nm fiber laser source with a high pulse repetition rate of up to 600 kHz combined with a fast-scanning mirror system. Microvasculature in SCID mouse ears is imaged at near real-time (0.5 fps) for a 1×1 mm2 field of view (FOV) with micron-scale lateral resolution. We also demonstrate imaging of cardiac-induced microhemodynamics in murine microvasculature at real-time frame-rates (30 fps) over a 250×250 μ FOV using real-time C-scan OR-PAM with ability to provide sustained imaging with near real-time feedback for focusing and positioning.

  3. Time-resolved ARPES with sub-15 fs temporal and near Fourier-limited spectral resolution

    NASA Astrophysics Data System (ADS)

    Rohde, G.; Hendel, A.; Stange, A.; Hanff, K.; Oloff, L.-P.; Yang, L. X.; Rossnagel, K.; Bauer, M.

    2016-10-01

    An experimental setup for time- and angle-resolved photoelectron spectroscopy with sub-15 fs temporal resolution is presented. A hollow-fiber compressor is used for the generation of 6.5 fs white light pump pulses, and a high-harmonic-generation source delivers 11 fs probe pulses at a photon energy of 22.1 eV. A value of 13 fs full width at half-maximum of the pump-probe cross correlation signal is determined by analyzing a photoemission intensity transient probing a near-infrared interband transition in 1T-TiSe2. Notably, the energy resolution of the setup conforms to typical values reported in conventional time-resolved photoemission studies using high harmonics, and an ultimate resolution of 170 meV is feasible.

  4. The IAU resolutions on astronomical reference systems, time scales, and earth rotation models : explanation and implementation

    NASA Astrophysics Data System (ADS)

    Kaplan, George H.

    Recent resolutions passed by the International Astronomical Union (IAU) on astronomical reference systems, time scales, and Earth rotation models are the most significant set of international agreements in positional astronomy in several decades. These resolutions, the result of over ten years of international research and study, provide a coherent set of foundational standards for the treatment of astrometric data and the modeling of dynamics in the solar system. This circular explains these resolutions and provides a complete set of practical formulas for their implementation. The six main chapters cover relativity, time scales, the fundamental celestial reference system, ephemerides of solar system bodies, precession and nutation, and modeling the Earth's rotation. "Errata in this circular and updates to it are given at http://aa.usno.navy.mil/publications/docs/Circular_179.html

  5. Dependence of the energy resolution of a scintillating crystal on the readout integration time

    NASA Astrophysics Data System (ADS)

    Bocci, V.; Chao, D.; Chiodi, G.; Faccini, R.; Ferroni, F.; Lunadei, R.; Martellotti, G.; Penso, G.; Pinci, D.; Recchia, L.

    2012-09-01

    The possibilty of performing high-rate calorimetry with a slow scintillating crystal is studied. In this experimental situation, to avoid pulse pile-up, it can be necessary to base the energy measurement on only a fraction of the emitted light, thus spoiling the energy resolution. This effect was experimentally studied with a BGO crystal and a photomultiplier followed by an integrator, by measuring the maximum amplitude of the signals. The experimental data show that the energy resolution is exclusively due to the statistical fluctuations of the number of photoelectrons contributing to the maximum amplitude. When such number is small its fluctuations are even smaller than those predicted by Poisson statistics. These results were confirmed by a Monte Carlo simulation which allows to estimate, in a general case, the energy resolution, given the total number of photoelectrons, the scintillation time and the integration time.

  6. Energy and coincidence time resolution measurements of CdTe detectors for PET.

    PubMed

    Ariño, G; Chmeissani, M; De Lorenzo, G; Puigdengoles, C; Cabruja, E; Calderón, Y; Kolstein, M; Macias-Montero, J G; Martinez, R; Mikhaylova, E; Uzun, D

    2013-02-01

    We report on the characterization of 2 mm thick CdTe diode detector with Schottky contacts to be employed in a novel conceptual design of PET scanner. Results at -8°C with an applied bias voltage of -1000 V/mm show a 1.2% FWHM energy resolution at 511 keV. Coincidence time resolution has been measured by triggering on the preamplifier output signal to improve the timing resolution of the detector. Results at the same bias and temperature conditions show a FWHM of 6 ns with a minimum acceptance energy of 500 keV. These results show that pixelated CdTe Schottky diode is an excellent candidate for the development of next generation nuclear medical imaging devices such as PET, Compton gamma cameras, and especially PET-MRI hybrid systems when used in a magnetic field immune configuration.

  7. The RMS survey. 13CO observations of candidate massive YSOs in the northern Galactic plane

    NASA Astrophysics Data System (ADS)

    Urquhart, J. S.; Busfield, A. L.; Hoare, M. G.; Lumsden, S. L.; Oudmaijer, R. D.; Moore, T. J. T.; Gibb, A. G.; Purcell, C. R.; Burton, M. G.; Maréchal, L. J. L.; Jiang, Z.; Wang, M.

    2008-08-01

    Context: The Red MSX Source (RMS) survey is an ongoing multi-wavelength observational programme designed to return a large, high-resolution mid-infrared colour-selected sample of massive young stellar objects (MYSOs). We have identified 2000 MYSO candidates located within our Galaxy by comparing the colours of MSX and 2MASS point sources to those of known MYSOs. The aim of our follow-up observations is to identify other objects with similar colours such as ultra compact (UC) HII regions, evolved stars and planetary nebulae (PNe) and distinguish between genuine MYSOs and nearby low-mass YSOs. Aims: A critical part of our follow-up programme is to conduct 13CO molecular line observations in order to determine kinematic distances to all of our MYSO candidates. These distances will be used in combination with far-IR and (sub)millimetre fluxes to determine bolometric luminosities which will allow us to identify and remove nearby low-mass YSOs. In addition these molecular line observations will help in identifying evolved stars which are weak CO emitters. Methods: We have used the 15 m James Clerk Maxwell Telescope (JCMT), the 13.7 m telescope of the Purple Mountain Observatory (PMO), the 20 m Onsala telescope and the 22 m Mopra telescope to conduct molecular line observations towards 508 MYSOs candidates located in the 1st and 2nd Quadrants. These observations have been made at the J=1-0 (Mopra, Onsala and PMO) and J=2-1 (JCMT) rotational transition frequency of 13CO molecules and have a spatial resolution of 20´´-55´´, a sensitivity of T{A}* ≃ 0.1 K and a velocity resolution of 0.2 km s-1. We complement these targeted observations with 13CO spectra extracted from the Galactic Ring Survey (GRS), which have a velocity resolution of 0.21 km s-1 and sensitivity T{A}* ≃ 0.13-0.2 K, towards a further 403 RMS sources. Results: In this paper we present the results and analysis of the 13CO spectra obtained towards 911 MYSO candidates. We detect 13CO emission towards 780

  8. Mapping atomic motions with ultrabright electrons: towards fundamental limits in space-time resolution.

    PubMed

    Manz, Stephanie; Casandruc, Albert; Zhang, Dongfang; Zhong, Yinpeng; Loch, Rolf A; Marx, Alexander; Hasegawa, Taisuke; Liu, Lai Chung; Bayesteh, Shima; Delsim-Hashemi, Hossein; Hoffmann, Matthias; Felber, Matthias; Hachmann, Max; Mayet, Frank; Hirscht, Julian; Keskin, Sercan; Hada, Masaki; Epp, Sascha W; Flöttmann, Klaus; Miller, R J Dwayne

    2015-01-01

    The long held objective of directly observing atomic motions during the defining moments of chemistry has been achieved based on ultrabright electron sources that have given rise to a new field of atomically resolved structural dynamics. This class of experiments requires not only simultaneous sub-atomic spatial resolution with temporal resolution on the 100 femtosecond time scale but also has brightness requirements approaching single shot atomic resolution conditions. The brightness condition is in recognition that chemistry leads generally to irreversible changes in structure during the experimental conditions and that the nanoscale thin samples needed for electron structural probes pose upper limits to the available sample or "film" for atomic movies. Even in the case of reversible systems, the degree of excitation and thermal effects require the brightest sources possible for a given space-time resolution to observe the structural changes above background. Further progress in the field, particularly to the study of biological systems and solution reaction chemistry, requires increased brightness and spatial coherence, as well as an ability to tune the electron scattering cross-section to meet sample constraints. The electron bunch density or intensity depends directly on the magnitude of the extraction field for photoemitted electron sources and electron energy distribution in the transverse and longitudinal planes of electron propagation. This work examines the fundamental limits to optimizing these parameters based on relativistic electron sources using re-bunching cavity concepts that are now capable of achieving 10 femtosecond time scale resolution to capture the fastest nuclear motions. This analysis is given for both diffraction and real space imaging of structural dynamics in which there are several orders of magnitude higher space-time resolution with diffraction methods. The first experimental results from the Relativistic Electron Gun for Atomic

  9. Mapping atomic motions with ultrabright electrons: towards fundamental limits in space-time resolution.

    PubMed

    Manz, Stephanie; Casandruc, Albert; Zhang, Dongfang; Zhong, Yinpeng; Loch, Rolf A; Marx, Alexander; Hasegawa, Taisuke; Liu, Lai Chung; Bayesteh, Shima; Delsim-Hashemi, Hossein; Hoffmann, Matthias; Felber, Matthias; Hachmann, Max; Mayet, Frank; Hirscht, Julian; Keskin, Sercan; Hada, Masaki; Epp, Sascha W; Flöttmann, Klaus; Miller, R J Dwayne

    2015-01-01

    The long held objective of directly observing atomic motions during the defining moments of chemistry has been achieved based on ultrabright electron sources that have given rise to a new field of atomically resolved structural dynamics. This class of experiments requires not only simultaneous sub-atomic spatial resolution with temporal resolution on the 100 femtosecond time scale but also has brightness requirements approaching single shot atomic resolution conditions. The brightness condition is in recognition that chemistry leads generally to irreversible changes in structure during the experimental conditions and that the nanoscale thin samples needed for electron structural probes pose upper limits to the available sample or "film" for atomic movies. Even in the case of reversible systems, the degree of excitation and thermal effects require the brightest sources possible for a given space-time resolution to observe the structural changes above background. Further progress in the field, particularly to the study of biological systems and solution reaction chemistry, requires increased brightness and spatial coherence, as well as an ability to tune the electron scattering cross-section to meet sample constraints. The electron bunch density or intensity depends directly on the magnitude of the extraction field for photoemitted electron sources and electron energy distribution in the transverse and longitudinal planes of electron propagation. This work examines the fundamental limits to optimizing these parameters based on relativistic electron sources using re-bunching cavity concepts that are now capable of achieving 10 femtosecond time scale resolution to capture the fastest nuclear motions. This analysis is given for both diffraction and real space imaging of structural dynamics in which there are several orders of magnitude higher space-time resolution with diffraction methods. The first experimental results from the Relativistic Electron Gun for Atomic

  10. Dose, exposure time, and resolution in Serial X-ray Crystallography

    SciTech Connect

    Starodub, D; Rez, P; Hembree, G; Howells, M; Shapiro, D; Chapman, H N; Fromme, P; Schmidt, K; Weierstall, U; Doak, R B; Spence, J C

    2007-03-22

    Using detailed simulation and analytical models, the exposure time is estimated for serial crystallography, where hydrated laser-aligned proteins are sprayed across a continuous synchrotron beam. The resolution of X-ray diffraction microscopy is limited by the maximum dose that can be delivered prior to sample damage. In the proposed Serial Crystallography method, the damage problem is addressed by distributing the total dose over many identical hydrated macromolecules running continuously in a single-file train across a continuous X-ray beam, and resolution is then limited only by the available fluxes of molecules and X-rays. Orientation of the diffracting molecules is achieved by laser alignment. We evaluate the incident X-ray fluence (energy/area) required to obtain a given resolution from (1) an analytical model, giving the count rate at the maximum scattering angle for a model protein, (2) explicit simulation of diffraction patterns for a GroEL-GroES protein complex, and (3) the frequency cut off of the transfer function following iterative solution of the phase problem, and reconstruction of a density map in the projection approximation. These calculations include counting shot noise and multiple starts of the phasing algorithm. The results indicate the number of proteins needed within the beam at any instant for a given resolution and X-ray flux. We confirm an inverse fourth power dependence of exposure time on resolution, with important implications for all coherent X-ray imaging. We find that multiple single-file protein beams will be needed for sub-nanometer resolution on current third generation synchrotrons, but not on fourth generation designs, where reconstruction of secondary protein structure at a resolution of 7 {angstrom} should be possible with short (below 100 s) exposures.

  11. Energy and time resolution of a LYSO matrix prototype for the Mu2e experiment

    NASA Astrophysics Data System (ADS)

    Atanov, N.; Baranov, V.; Colao, F.; Cordelli, M.; Corradi, G.; Dané, E.; Davydov, Yu. I.; Flood, K.; Giovannella, S.; Glagolev, V.; Happacher, F.; Hitlin, D. G.; Martini, M.; Miscetti, S.; Miyashita, T.; Morescalchi, L.; Ott, P.; Pezzullo, G.; Saputi, A.; Sarra, I.; Soleti, S. R.; Tassielli, G.; Tereshchenko, V.; Thomas, A.

    2016-07-01

    We have measured the performances of a LYSO crystal matrix prototype tested with electron and photon beams in the energy range 60-450 MeV. This study has been carried out to determine the achievable energy and time resolutions for the calorimeter of the Mu2e experiment.

  12. Energy and time resolution of a LYSO matrix prototype for the Mu2e experiment

    SciTech Connect

    Atanov, N.; Baranov, V.; Colao, F.; Cordelli, M.; Corradi, G.; Dane, E.; Davydov, Yu. I.; Flood, K.; Giovannella, S.; Glagolev, V.; Happacher, F.; Hitlin, D. G.; Martini, M.; Miscetti, S.; Miyashita, T.; Morescalchi, L.; Ott, P.; Pezzullo, G.; Saputi, A.; Sarra, I.; Soleti, S. R.; Tassielli, G.; Tereshchenko, V.; Thomas, A.

    2015-09-28

    We have measured the performances of a LYSO crystal matrix prototype tested with electron and photon beams in the energy range 60–450 MeV. Furthermore, this study has been carried out to determine the achievable energy and time resolutions for the calorimeter of the Mu2e experiment.

  13. A novel approach for pulse width measurements with a high precision (8 ps RMS) TDC in an FPGA

    NASA Astrophysics Data System (ADS)

    Ugur, C.; Linev, S.; Michel, J.; Schweitzer, T.; Traxler, M.

    2016-01-01

    High precision time measurements are a crucial element in particle identification experiments, which likewise require pulse width information for Time-over-Threshold (ToT) measurements and charge measurements (correlated with pulse width). In almost all of the FPGA-based TDC applications, pulse width measurements are implemented using two of the TDC channels for leading and trailing edge time measurements individually. This method however, requires twice the number of resources. In this paper we present the latest precision improvements in the high precision TDC (8 ps RMS) developed before [1], as well as the novel way of measuring ToT using a single TDC channel, while still achieving high precision (as low as 11.7 ps RMS). The effect of voltage, generated by a DC-DC converter, over the precision is also discussed. Finally, the outcome of the temperature change over the pulse width measurement is shown and a correction method is suggested to limit the degradation.

  14. Estimating maximum instantaneous distortion from inlet total pressure rms and PSD measurements. [Root Mean Square and Power Spectral Density methods

    NASA Technical Reports Server (NTRS)

    Melick, H. C., Jr.; Ybarra, A. H.; Bencze, D. P.

    1975-01-01

    An inexpensive method is developed to determine the extreme values of instantaneous inlet distortion. This method also provides insight into the basic mechanics of unsteady inlet flow and the associated engine reaction. The analysis is based on fundamental fluid dynamics and statistical methods to provide an understanding of the turbulent inlet flow and quantitatively relate the rms level and power spectral density (PSD) function of the measured time variant total pressure fluctuations to the strength and size of the low pressure regions. The most probable extreme value of the instantaneous distortion is then synthesized from this information in conjunction with the steady state distortion. Results of the analysis show the extreme values to be dependent upon the steady state distortion, the measured turbulence rms level and PSD function, the time on point, and the engine response characteristics. Analytical projections of instantaneous distortion are presented and compared with data obtained by a conventional, highly time correlated, 40 probe instantaneous pressure measurement system.

  15. Nanosecond Time-Resolution Study of Gold Nanorod Rotation at the Liquid-Solid Interface.

    PubMed

    Neupane, Bhanu; Chen, Fang; Wei, Yanli; Fang, Ning; Ligler, Frances S; Wang, Gufeng

    2016-07-18

    Early studies showed that the adsorption of nanorods may start from a special "anchored" state, in which the nanorods lose translational motion but retain rotational freedom. Insight into how the anchored nanorods rotate should provide additional dimensions for understanding particle-surface interactions. Based on conventional time-resolution studies, gold nanorods are thought to continuously rotate following initial interactions with negatively charged glass surfaces. However, this nanosecond time-resolution study reveals that the apparent continuous rotation actually consists of numerous fast, intermittent rotations or transitions between a small number of weakly immobilized states, with the particle resting in the immobilized states most of the time. The actual rotation from one immobilized state to the other happens on a 1 ms timescale, that is, approximately 50 times slower than in the bulk solution.

  16. Computationally efficient image restoration and super-resolution algorithns for real-time implementation

    NASA Astrophysics Data System (ADS)

    Sundareshan, Malur K.

    2002-07-01

    Computational complexity is a major impediment to the real- time implementation of image restoration and super- resolution algorithms. Although powerful restoration algorithms have been developed within the last few years utilizing sophisticated mathematical machinery (based on statistical optimization and convex set theory), these algorithms are typically iterative in nature and require enough number of iterations to be executed to achieve desired resolution gains in order to meaningfully perform detection and recognition tasks in practice. Additionally, recent technological breakthroughs have facilitated novel sensor designs (focal plane arrays, for instance) that make it possible to capture mega-pixel imagery data at video frame rates. A major challenge in the processing of these large format images is to complete the execution of the image processing steps within the frame capture times and to keep up with the output rate of the sensor so that all data captured by the sensor can be efficiently utilized. Consequently, development of novel methods that facilitate real-time implementation of image restoration and super- resolution algorithms is of significant practical interest and will be the primary focus of this paper. The key to designing computationally efficient processing schemes lies in strategically introducing appropriate pre-processing and post-processing steps together with the super-resolution iterations in order to tailor optimized overall processing sequences for imagery data of specific formats. Three distinct methods for tailoring a pre-processing filter and integrating it with the super-resolution processing steps will be outlined in this paper. These methods consist of a Region-of-Interest (ROI) extraction scheme, a background- detail separation procedure, and a scene-derived information extraction step for implementing a set-theoretic restoration of the image that is less demanding in computation compared to the super-resolution iterations. A

  17. A high-resolution, four-band SAR testbed with real-time image formation

    SciTech Connect

    Walker, B.; Sander, G.; Thompson, M.; Burns, B.; Fellerhoff, R.; Dubbert, D.

    1996-03-01

    This paper describes the Twin-Otter SAR Testbed developed at Sandia National Laboratories. This SAR is a flexible, adaptable testbed capable of operation on four frequency bands: Ka, Ku, X, and VHF/UHF bands. The SAR features real-time image formation at fine resolution in spotlight and stripmap modes. High-quality images are formed in real time using the overlapped subaperture (OSA) image-formation and phase gradient autofocus (PGA) algorithms.

  18. Precise timing resolution measurements of GSO scintillators with different Ce concentrations combined with silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Okumura, Satoshi; Yamamoto, Seiichi; Yeol Yeom, Jung; Shimura, Naoaki; Ishibashi, Hiroyuki

    2015-10-01

    Ce doped Gd2SiO5 (GSO) is a scintillator which has relatively fast decay time, high density, high light output, and is used for commercial PET systems. However as time-of-flight (TOF) PET systems become more popular in clinical diagnostic, GSO seems less attractive, because its performance is thought to be insufficient for use in TOF-PET application. Although the timing resolution of the GSO combined with photomultiplier tube (PMT) is known to be inappropriate for TOF-PET system, the performance of GSO coupled to silicon photomultipliers (Si-PM) has not been reported to date. In addition, GSO possesses a variety of decay times depending on its Ce concentration. We measured basic performance of GSOs with different Ce concentrations and then coupled them to Si-PMs to measure the precise timing resolution using a high bandwidth digital oscilloscope. The decay time of GSO with 0.4 mol% Ce were longer (63±4 ns) compared with those with 1.0 mol% (40±2 ns) and 1.5 mol% (33±1 ns). With a Si-PM, the photo-peak channels were almost the same for GSOs with 0.4 mol% Ce and those with 1.5 mol% Ce, but the GSO with 1.0 mol% Ce was ~25% higher. Energy resolutions of these three GSOs were ~13% full-width at half-maximum (FWHM) for 662 keV gamma photons without correcting for saturation effects. When coupled to Si-PMs, the timing resolution for GSO with 1.5 mol% Ce (decay time 33 ns) was 549 ps FWHM, almost good enough to use for TOF-PET system. The combination of GSO with 1.5 mol% Ce with Si-PM will be an interesting combination to realize low cost TOF-PET systems.

  19. Branching Mutant rms-2 in Pisum sativum (Grafting Studies and Endogenous Indole-3-Acetic Acid Levels).

    PubMed Central

    Beveridge, C. A.; Ross, J. J.; Murfet, I. C.

    1994-01-01

    Isogenic lines of pea (Pisum sativum L.) were used to determine the physiological site of action of the Rms-2 gene, which maintains apical dominance, and its effect on endogenous free indole-3-acetic acid (IAA) levels. In mutant rms-2 scions, which normally produce lateral branches below node 3 and above node 7, apical dominance was almost fully restored by grafting to Rms-2 (wild-type) stocks. In the reciprocal grafts, rms-2 stocks did not promote branching in wild-type shoots. Together, these results suggest that the Rms-2 gene inhibits branching in the shoot of pea by controlling the synthesis of a translocatable (hormone-like) substance that is produced in the roots and/or cotyledons and in the shoot. At all stages, including the stage at which aerial lateral buds commence outgrowth, the level of IAA in rms-2 shoots was elevated (up to 5-fold) in comparison with that in wild-type shoots. The internode length of rms-2 plants was 40% less than in wild-type plants, and the mutant plants allocated significantly more dry weight to the shoot than to the root in comparison with wild-type plants. Grafting to wild-type stocks did not normalize IAA levels or internode length in rms-2 scions, even though it inhibited branching, suggesting that the involvement of Rms-2 in the control of IAA level and internode length may be confined to processes in the shoot. PMID:12232140

  20. The Ultimate Resolution Criterion For Out-Of-The-Cockpit Visual Scene Generation In Real Time

    NASA Astrophysics Data System (ADS)

    Setty, K. S. L.

    1980-12-01

    Visual system resolution is the first important criterion mentioned in a functional specification for the real time dynamic simulation of any visual system. This criterion has a profound effect on the estimation of the cost and the complexity of any dynamic visual system design of very wide field of view. What is essential in terms of static and dynamic resolution of the simulated visual system for proper pilot training in tactical combat missions is described in this paper, around a spectrum of highly relevant conjectures such as the physical limit of computer processing, innovations in digital image processing, and the speed of perception in visual information processing by the human brain.

  1. High-resolution detection system for time-of-flight electron spectrometry

    SciTech Connect

    Hussain, Zahid; Tremsin, A.S.; Lebedev, G.V.; Siegmund, O.H.W.; Vallerga, J.V.; McPhate, J.B.; Hussain, Z.

    2007-08-12

    One of the key components of a time-of-flight (TOF) spectrometer is the detection system. In addition to high timing resolution, accurate two-dimensional imaging substantially broadensthe areas of applications of TOF spectrometers; for example, add a new dimension to angle-resolved photoemission spectroscopy (ARPES). In this paper we report on the recent developments of a high spatial (<50 mm) and timing (<130 ps) resolution imaging system capable of selective detection of electrons, ions and/or photons. Relative to our previously reported results, we have substantially improved the counting rate capabilities of the system especially for cases where the energy range of interest represents a small fraction of the incoming flux at the detector plane. The new system ignores all the events outside of a tunable time window substantially decreasing the dead time required for the event processing. That allows high-resolution TOF measurements within a given energy or momentum range and also can be used for distinguishing (or disabling) detection of photons versus detection of charged particles. The counting rate within a given energy window can be as high as ~;;400KHz at 10percent dead time. The electron detection system reported in the paper was developed for the TOF ARPES experiments at the Advanced Light Source, Lawrence Berkeley National Laboratory.

  2. A Compact Liquid Xenon Compton Telescope with High Energy Resolution and Time-of-Flight

    NASA Astrophysics Data System (ADS)

    Oberlack, Uwe; Gomez, R.; Olsen, C.; Shagin, P.; Aprile, E.; Giboni, K.; Plante, G.; Santorelli, R.

    2006-09-01

    Two recent developments have led us to propose a new type of Compton telescope in compact geometry with time-of-flight, for gamma-ray astronomy in the energy regime of 0.2 - 10 MeV. First, the technology of vacuum ultraviolet photosensors for efficient and fast readout of liquid xenon (LXe) scintillation light has improved dramatically over the last few years, and new developments are underway. A LXe Advanced Compton Telescope would consist of two detector arrays of LXe time projection chambers in compact geometry, with time-of-flight (ToF) between detector modules at a resolution of order 100 ps. Second, the previously achieved moderate energy resolution in LXe, a significant draw-back for gamma-ray line spectroscopy, has been found to be largely due to a strong anti-correlation of ionization and scintillation in LXe. Efficient measurement of both charge and light enables us to improve energy resolution greatly. A factor of three improvement over a previous prototype, LXeGRIT, has already been achieved, and the measured underlying physics indicate the possibility of achievng energy resolution below 1% FWHM at 1 MeV. We are vigorously working on improving light and charge readout to realize this potential in a practical detector. We report on the status and prospects of our current research and development program. This work is supported by NASA grant NNG05WC24G.

  3. Time resolution of the plastic scintillator strips with matrix photomultiplier readout for J-PET tomograph.

    PubMed

    Moskal, P; Rundel, O; Alfs, D; Bednarski, T; Białas, P; Czerwiński, E; Gajos, A; Giergiel, K; Gorgol, M; Jasińska, B; Kamińska, D; Kapłon, Ł; Korcyl, G; Kowalski, P; Kozik, T; Krzemień, W; Kubicz, E; Niedźwiecki, Sz; Pałka, M; Raczyński, L; Rudy, Z; Sharma, N G; Słomski, A; Silarski, M; Strzelecki, A; Wieczorek, A; Wiślicki, W; Witkowski, P; Zieliński, M; Zoń, N

    2016-03-01

    Recent tests of a single module of the Jagiellonian Positron Emission Tomography system (J-PET) consisting of 30 cm long plastic scintillator strips have proven its applicability for the detection of annihilation quanta (0.511 MeV) with a coincidence resolving time (CRT) of 0.266 ns. The achieved resolution is almost by a factor of two better with respect to the current TOF-PET detectors and it can still be improved since, as it is shown in this article, the intrinsic limit of time resolution for the determination of time of the interaction of 0.511 MeV gamma quanta in plastic scintillators is much lower. As the major point of the article, a method allowing to record timestamps of several photons, at two ends of the scintillator strip, by means of matrix of silicon photomultipliers (SiPM) is introduced. As a result of simulations, conducted with the number of SiPM varying from 4 to 42, it is shown that the improvement of timing resolution saturates with the growing number of photomultipliers, and that the [Formula: see text] configuration at two ends allowing to read twenty timestamps, constitutes an optimal solution. The conducted simulations accounted for the emission time distribution, photon transport and absorption inside the scintillator, as well as quantum efficiency and transit time spread of photosensors, and were checked based on the experimental results. Application of the [Formula: see text] matrix of SiPM allows for achieving the coincidence resolving time in positron emission tomography of [Formula: see text]0.170 ns for 15 cm axial field-of-view (AFOV) and [Formula: see text]0.365 ns for 100 cm AFOV. The results open perspectives for construction of a cost-effective TOF-PET scanner with significantly better TOF resolution and larger AFOV with respect to the current TOF-PET modalities. PMID:26895187

  4. Time resolution of the plastic scintillator strips with matrix photomultiplier readout for J-PET tomograph

    NASA Astrophysics Data System (ADS)

    Moskal, P.; Rundel, O.; Alfs, D.; Bednarski, T.; Białas, P.; Czerwiński, E.; Gajos, A.; Giergiel, K.; Gorgol, M.; Jasińska, B.; Kamińska, D.; Kapłon, Ł.; Korcyl, G.; Kowalski, P.; Kozik, T.; Krzemień, W.; Kubicz, E.; Niedźwiecki, Sz; Pałka, M.; Raczyński, L.; Rudy, Z.; Sharma, N. G.; Słomski, A.; Silarski, M.; Strzelecki, A.; Wieczorek, A.; Wiślicki, W.; Witkowski, P.; Zieliński, M.; Zoń, N.

    2016-03-01

    Recent tests of a single module of the Jagiellonian Positron Emission Tomography system (J-PET) consisting of 30 cm long plastic scintillator strips have proven its applicability for the detection of annihilation quanta (0.511 MeV) with a coincidence resolving time (CRT) of 0.266 ns. The achieved resolution is almost by a factor of two better with respect to the current TOF-PET detectors and it can still be improved since, as it is shown in this article, the intrinsic limit of time resolution for the determination of time of the interaction of 0.511 MeV gamma quanta in plastic scintillators is much lower. As the major point of the article, a method allowing to record timestamps of several photons, at two ends of the scintillator strip, by means of matrix of silicon photomultipliers (SiPM) is introduced. As a result of simulations, conducted with the number of SiPM varying from 4 to 42, it is shown that the improvement of timing resolution saturates with the growing number of photomultipliers, and that the 2× 5 configuration at two ends allowing to read twenty timestamps, constitutes an optimal solution. The conducted simulations accounted for the emission time distribution, photon transport and absorption inside the scintillator, as well as quantum efficiency and transit time spread of photosensors, and were checked based on the experimental results. Application of the 2× 5 matrix of SiPM allows for achieving the coincidence resolving time in positron emission tomography of ≈ 0.170 ns for 15 cm axial field-of-view (AFOV) and ≈ 0.365 ns for 100 cm AFOV. The results open perspectives for construction of a cost-effective TOF-PET scanner with significantly better TOF resolution and larger AFOV with respect to the current TOF-PET modalities.

  5. Time resolution of the plastic scintillator strips with matrix photomultiplier readout for J-PET tomograph.

    PubMed

    Moskal, P; Rundel, O; Alfs, D; Bednarski, T; Białas, P; Czerwiński, E; Gajos, A; Giergiel, K; Gorgol, M; Jasińska, B; Kamińska, D; Kapłon, Ł; Korcyl, G; Kowalski, P; Kozik, T; Krzemień, W; Kubicz, E; Niedźwiecki, Sz; Pałka, M; Raczyński, L; Rudy, Z; Sharma, N G; Słomski, A; Silarski, M; Strzelecki, A; Wieczorek, A; Wiślicki, W; Witkowski, P; Zieliński, M; Zoń, N

    2016-03-01

    Recent tests of a single module of the Jagiellonian Positron Emission Tomography system (J-PET) consisting of 30 cm long plastic scintillator strips have proven its applicability for the detection of annihilation quanta (0.511 MeV) with a coincidence resolving time (CRT) of 0.266 ns. The achieved resolution is almost by a factor of two better with respect to the current TOF-PET detectors and it can still be improved since, as it is shown in this article, the intrinsic limit of time resolution for the determination of time of the interaction of 0.511 MeV gamma quanta in plastic scintillators is much lower. As the major point of the article, a method allowing to record timestamps of several photons, at two ends of the scintillator strip, by means of matrix of silicon photomultipliers (SiPM) is introduced. As a result of simulations, conducted with the number of SiPM varying from 4 to 42, it is shown that the improvement of timing resolution saturates with the growing number of photomultipliers, and that the [Formula: see text] configuration at two ends allowing to read twenty timestamps, constitutes an optimal solution. The conducted simulations accounted for the emission time distribution, photon transport and absorption inside the scintillator, as well as quantum efficiency and transit time spread of photosensors, and were checked based on the experimental results. Application of the [Formula: see text] matrix of SiPM allows for achieving the coincidence resolving time in positron emission tomography of [Formula: see text]0.170 ns for 15 cm axial field-of-view (AFOV) and [Formula: see text]0.365 ns for 100 cm AFOV. The results open perspectives for construction of a cost-effective TOF-PET scanner with significantly better TOF resolution and larger AFOV with respect to the current TOF-PET modalities.

  6. An Accurate Timing Alignment Method with Time-to-Digital Converter Linearity Calibration for High-Resolution TOF PET

    PubMed Central

    Li, Hongdi; Wang, Chao; An, Shaohui; Lu, Xingyu; Dong, Yun; Liu, Shitao; Baghaei, Hossain; Zhang, Yuxuan; Ramirez, Rocio; Wong, Wai-Hoi

    2015-01-01

    Accurate PET system timing alignment minimizes the coincidence time window and therefore reduces random events and improves image quality. It is also critical for time-of-flight (TOF) image reconstruction. Here, we use a thin annular cylinder (shell) phantom filled with a radioactive source and located axially and centrally in a PET camera for the timing alignment of a TOF PET system. This timing alignment method involves measuring the time differences between the selected coincidence detector pairs, calibrating the differential and integral nonlinearity of the time-to-digital converter (TDC) with the same raw data and deriving the intrinsic time biases for each detector using an iterative algorithm. The raw time bias for each detector is downloaded to the front-end electronics and the residual fine time bias can be applied during the TOF list-mode reconstruction. Our results showed that a timing alignment accuracy of better than ±25 ps can be achieved, and a preliminary timing resolution of 473 ps (full width at half maximum) was measured in our prototype TOF PET/CT system. PMID:26543243

  7. Enhanced focal-resolution of dipole sources using aeroacoustic time-reversal in a wind tunnel

    NASA Astrophysics Data System (ADS)

    Mimani, A.; Moreau, D. J.; Prime, Z.; Doolan, C. J.

    2016-05-01

    This paper presents the first application of the Point-Time-Reversal-Sponge-Layer (PTRSL) damping technique to enhance the focal-resolution of experimental flow-induced dipole sources obtained using the Time-Reversal (TR) source localization method. Experiments were conducted in an Anechoic Wind Tunnel for the case of a full-span cylinder located in a low Mach number cross-flow. The far-field acoustic pressure sampled using two line arrays of microphones located above and below the cylinder exhibited a dominant Aeolian tone. The aeroacoustic TR simulations were implemented using the time-reversed signals whereby the source map revealed the lift-dipole nature at the Aeolian tone frequency. A PTRSL (centred at the predicted dipole location) was shown to reduce the size of dipole focal spots to 7/20th of a wavelength as compared to one wavelength without its use, thereby dramatically enhancing the focal-resolution of the TR technique.

  8. Perturbing high-resolution precipitation time series to represent future climates

    NASA Astrophysics Data System (ADS)

    Jomo Danielsen Sørup, Hjalte; Arnbjerg-Nielsen, Karsten

    2016-04-01

    Climate change impact water management worldwide as the water cycle is embedded in the climate system. For urban infrastructure the time resolution of precipitation data needed for design and planning (minutes) is much finer than what is normally provided by climate models (hourly to daily). Thus, a lot of effort is put into giving reliable estimates of what the expected change in precipitation will be at these fine scales. The relevant urban design criteria span from the minute scale up to yearly water balance scale and time series that show realistic changes across these scales and all those in-between are needed. Generally, fine resolution precipitation time series for future climates do not exist and a multitude of statistical approaches exist to try to overcome this problem. RCM outputs must be downscaled to higher spatial and temporal resolution to meet these needs. This is often done by applying weather generators or scaling of model output statistics. Both of these methods have known shortcomings in generating representative time series at the sub-hourly to hourly time scales. In the present study we utilize 1) that we have high resolution precipitation for present climate in the form of observational data, and 2) that we have robust estimates on how precipitation will change due to climate change for all temporal scales. This latter is quantified through change factors which are available for yearly and seasonal precipitation as well as for short term extreme events for a range of return periods. We demonstrate a novel methodology where the regional knowledge about expected changes in precipitation through the use of Intensity-Frequency-Duration (IDF) relationships is used to non-linearly perturb existing precipitation time series at 1-minute resolution to reflect complex expectations to a future changed climate. The methodology process the precipitation time series at event level where individual change factors are calculated based on the actual IDF

  9. A near-infrared SETI experiment: A multi-time resolution data analysis

    NASA Astrophysics Data System (ADS)

    Tallis, Melisa; Maire, Jerome; Wright, Shelley; Drake, Frank D.; Duenas, Andres; Marcy, Geoffrey W.; Stone, Remington P. S.; Treffers, Richard R.; Werthimer, Dan; NIROSETI

    2016-06-01

    We present new post-processing routines which are used to detect very fast optical and near-infrared pulsed signals using the latest NIROSETI (Near-Infrared Optical Search for Extraterrestrial Intelligence) instrument. NIROSETI was commissioned in 2015 at Lick Observatory and searches for near-infrared (0.95 to 1.65μ) nanosecond pulsed laser signals transmitted by distant civilizations. Traditional optical SETI searches rely on analysis of coincidences that occur between multiple detectors at a fixed time resolution. We present a multi-time resolution data analysis that extends our search from the 1ns to 1ms range. This new feature greatly improves the versatility of the instrument and its search parameters for near-infrared SETI. We aim to use these algorithms to assist us in our search for signals that have varying duty cycles and pulse widths. We tested the fidelity and robustness of our algorithms using both synthetic embedded pulsed signals, as well as data from a near-infrared pulsed laser installed on the instrument. Applications of NIROSETI are widespread in time domain astrophysics, especially for high time resolution transients, and astronomical objects that emit short-duration high-energy pulses such as pulsars.

  10. A multi-channel high time resolution detector for high content imaging

    NASA Astrophysics Data System (ADS)

    Lapington, J. S.; Fraser, G. W.; Miller, G. M.; Ashton, T. J. R.; Jarron, P.; Despeisse, M.; Powolny, F.; Howorth, J.; Milnes, J.

    2009-10-01

    Medical imaging has long benefited from advances in photon counting detectors arising from space and particle physics. We describe a microchannel plate-based detector system for high content (multi-parametric) analysis, specifically designed to provide a step change in performance and throughput for measurements in imaged live cells and tissue for the 'omics'. The detector system integrates multi-channel, high time resolution, photon counting capability into a single miniaturized detector with integrated ASIC electronics, comprising a fast, low power amplifier discriminator and TDC for every channel of the discrete pixel electronic readout, and achieving a pixel density improvement of order two magnitudes compared with current comparable devices. The device combines high performance, easy reconfigurability, and economy within a compact footprint. We present simulations and preliminary measurements in the context of our ultimate goals of 20 ps time resolution with multi-channel parallel analysis (1024 channels).

  11. A pulse-front-tilt-compensated streaked optical spectrometer with high throughput and picosecond time resolution

    NASA Astrophysics Data System (ADS)

    Katz, J.; Boni, R.; Rivlis, R.; Muir, C.; Froula, D. H.

    2016-11-01

    A high-throughput, broadband optical spectrometer coupled to the Rochester optical streak system equipped with a Photonis P820 streak tube was designed to record time-resolved spectra with 1-ps time resolution. Spectral resolution of 0.8 nm is achieved over a wavelength coverage range of 480 to 580 nm, using a 300-groove/mm diffraction grating in conjunction with a pair of 225-mm-focal-length doublets operating at an f/2.9 aperture. Overall pulse-front tilt across the beam diameter generated by the diffraction grating is reduced by preferentially delaying discrete segments of the collimated input beam using a 34-element reflective echelon optic. The introduced delay temporally aligns the beam segments and the net pulse-front tilt is limited to the accumulation across an individual sub-element. The resulting spectrometer design balances resolving power and pulse-front tilt while maintaining high throughput.

  12. High-Time-Resolution Streak Photographic System Equipped with Propellant Guns for Hugoniot Measurement of Solids

    NASA Astrophysics Data System (ADS)

    Mashimo, Tsutomu; Zhang, Yuyang; Uchino, Masakazu; Nakamura, Akira

    2009-09-01

    The high-time-resolution streak photographic system equipped with a powder gun and a two-stage light gas gun has been constructed for the Hugoniot measurement of solids at pressures up to >300 GPa. For this system, a compact rotating-mirror-type streak camera and a long-pulsed dye laser with no Q-switch were produced. A time resolution higher than 1 ns was achieved by using a 2-µm-wide slit of the camera formed using the laser. The shock velocity and particle velocity of steady shock waves of the materials with a shock velocity of ˜6 km/s can be measured by the inclined-mirror method with the basic errors of 0.2 and 0.1-0.2%, and 0.2 and 0.35-0.45% for symmetrical and asymmetrical impact, respectively, depending on shock velocity and impact velocity.

  13. Performances of a solid streak camera based on conventional CCD with nanosecond time resolution

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Bai, Yonglin; Zhu, Bingli; Gou, Yongsheng; Xu, Peng; Bai, XiaoHong; Liu, Baiyu; Qin, Junjun

    2015-02-01

    Imaging systems with high temporal resolution are needed to study rapid physical phenomena ranging from shock waves, including extracorporeal shock waves used for surgery, to diagnostics of laser fusion and fuel injection in internal combustion engines. However, conventional streak cameras use a vacuum tube making thus fragile, cumbersome and expensive. Here we report an CMOS streak camera project consists in reproducing completely this streak camera functionality with a single CMOS chip. By changing the mode of charge transfer of CMOS image sensor, fast photoelectric diagnostics of single point with linear CMOS and high-speed line scanning with array CMOS sensor can be achieved respectively. A fast photoelectric diagnostics system has been designed and fabricated to investigate the feasibility of this method. Finally, the dynamic operation of the sensors is exposed. Measurements show a sample time of 500 ps and a time resolution better than 2 ns.

  14. Particle acceleration due to shocks in the interplanetary field: High time resolution data and simulation results

    NASA Technical Reports Server (NTRS)

    Kessel, R. L.; Armstrong, T. P.; Nuber, R.; Bandle, J.

    1985-01-01

    Data were examined from two experiments aboard the Explorer 50 (IMP 8) spacecraft. The Johns Hopkins University/Applied Lab Charged Particle Measurement Experiment (CPME) provides 10.12 second resolution ion and electron count rates as well as 5.5 minute or longer averages of the same, with data sampled in the ecliptic plane. The high time resolution of the data allows for an explicit, point by point, merging of the magnetic field and particle data and thus a close examination of the pre- and post-shock conditions and particle fluxes associated with large angle oblique shocks in the interplanetary field. A computer simulation has been developed wherein sample particle trajectories, taken from observed fluxes, are allowed to interact with a planar shock either forward or backward in time. One event, the 1974 Day 312 shock, is examined in detail.

  15. Astronaut Jeffrey Hoffman on RMS robot arm during HST repairs

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Astronaut Jeffrey A. Hoffman (frame center) remains secured by his feet on the end of the Endeavour's robot arm as he prepares to participate in the replacement of Hubble Space Telescope's (HST) Wide Field/Planetary Camera (WF/PC). Astronaut F. Story Musgrave (just in frame at lower left corner) assists Hoffman in removing the new camera (WF/PC2) from the Scientific Instrument Protective Enclosure (SIPE). Electronic still photography is technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality.

  16. A time-accurate high-resolution TVD scheme for solving the Navier-Stokes equations

    NASA Technical Reports Server (NTRS)

    Kim, Hyun Dae; Liu, Nan-Suey

    1992-01-01

    A total variation diminishing (TVD) scheme has been developed and incorporated into an existing time-accurate high-resolution Navier-Stokes code. The accuracy and the robustness of the resulting solution procedure have been assessed by performing many calculations in four different areas: shock tube flows, regular shock reflection, supersonic boundary layer, and shock boundary layer interactions. These numerical results compare well with corresponding exact solutions or experimental data.

  17. A time-accurate high-resolution TVD scheme for solving the Navier-Stokes equations

    NASA Technical Reports Server (NTRS)

    Kim, Hyun D.; Liu, Nan-Suey

    1993-01-01

    A total variation diminishing (TVD) scheme has been developed and incorporated into an existing time-accurate high-resolution Navier-Stokes code. The accuracy and the robustness of the resulting solution procedure have been assessed by performing many calculations in four different areas: shock tube flows, regular shock reflection, supersonic boundary layer, and shock boundary layer interactions. These numerical results compare well with corresponding exact solutions or experimental data.

  18. Divergence identities in curved space-time a resolution of the stress-energy problem

    NASA Astrophysics Data System (ADS)

    Yilmaz, Hüseyin

    1989-03-01

    It is noted that the joint use of two basic differential identities in curved space-time, namely, 1) the Einstein-Hilbert identity (1915), and 2) the identity of P. Freud (1939), permits a viable alternative to general relativity and a resolution of the "field stress-energy" problem of the gravitational theory. (A tribute to Eugene P. Wigner's 1957 presidential address to the APS)

  19. A high time resolution study of the solar wind-magnetosphere energy coupling function

    NASA Technical Reports Server (NTRS)

    Akasofu, S.-I.; Carbary, J. F.; Meng, C.-I.; Sullivan, J. P.; Lepping, R. P.

    1982-01-01

    A high time resolution study of the relationships between the solar wind-magnetosphere energy coupling function and the total energy dissipation rate of the magnetosphere is made using 5-min average values of solar wind data and of the geomagnetic indices AE and Dst. All the results are essentially the same as those obtained by the earlier studies which were based on the hourly average data set. Therefore, it is confirmed that the magnetosphere is primarily a driven system

  20. Improving Horizontal Resolution of High-frequency Surface-wave Methods Using Travel-time Tomography

    NASA Astrophysics Data System (ADS)

    Yin, X.; Xia, J.; Sun, S.; Shen, C.

    2015-12-01

    In surface-wave methods, horizontal resolution can be defined as the ability to distinguish anomalous objects that are laterally displaced from each other. And the horizontal length of a recognizable geological anomalous body is measured by the lateral variation of S-wave velocity. Multichannel analysis of surface waves (MASW) method is an efficient tool to determine near-surface shear-wave velocities. The acquisition of the MASW method involves the same source-receiver configuration moved successively by a fixed distance interval (a few to several stations) along a linear survey line, which is called a roll-along acquisition geometry. A pseudo-2D S-wave velocity section is constructed by aligning 1D models, and each inverted 1D S-wave velocity model reflects the vertical S-wave velocity variation at the midpoint of each geophone spread. Although the MASW method can improve the horizontal resolution of S-wave velocity sections to some degree, the amount of fieldwork is increased by the roll-along acquisition geometry. We propose surface-wave tomography method to investigate horizontal resolution of surface-wave exploration. Phase-velocity dispersion curves are calculated by a pair of traces within a multichannel record through cross-correlation combined with a phase-shift scanning method. Then with the utilization of travel-time tomography, we can obtain high resolution pure-path dispersion curves with diverse sizes of grids at different frequencies. Finally, the pseudo-2D S-wave velocity structure is reconstructed by inverting the pure-path dispersion curves. Travel-time tomography of surface waves can extract accurate dispersion curves from a record with a short receiver spacing, and it can effectively enhance the ability of random noise immunity. Synthetic tests and a real-world example have indicated that travel-time tomography has a great potential for improving the horizontal resolution of surface waves. Keywords: Travel-time tomography of surface waves

  1. Building Change Detection in Very High Resolution Satellite Stereo Image Time Series

    NASA Astrophysics Data System (ADS)

    Tian, J.; Qin, R.; Cerra, D.; Reinartz, P.

    2016-06-01

    There is an increasing demand for robust methods on urban sprawl monitoring. The steadily increasing number of high resolution and multi-view sensors allows producing datasets with high temporal and spatial resolution; however, less effort has been dedicated to employ very high resolution (VHR) satellite image time series (SITS) to monitor the changes in buildings with higher accuracy. In addition, these VHR data are often acquired from different sensors. The objective of this research is to propose a robust time-series data analysis method for VHR stereo imagery. Firstly, the spatial-temporal information of the stereo imagery and the Digital Surface Models (DSMs) generated from them are combined, and building probability maps (BPM) are calculated for all acquisition dates. In the second step, an object-based change analysis is performed based on the derivative features of the BPM sets. The change consistence between object-level and pixel-level are checked to remove any outlier pixels. Results are assessed on six pairs of VHR satellite images acquired within a time span of 7 years. The evaluation results have proved the efficiency of the proposed method.

  2. Efficiency and timing resolution of scintillator tiles read out with silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Pooth, O.; Weingarten, S.; Weinstock, L.

    2016-01-01

    Silicon photomultipliers (SiPM) are semiconductor photo sensors that have the potential to replace photomultiplier tubes (PMT) in various fields of application. We present detectors consisting of 30 × 30 × 0.5 cm3 fast plastic scintillator tiles read out with SiPMs. The detectors offer great electronic and mechanical advantages over the classical PMT-scintillator combination. SiPMs are very compact devices that run independent of magnetic fields at low voltages and no light guides between the scintillator and the SiPM are necessary in the presented layouts. Three prototypes, two of which with integrated wavelength shifting fibres, have been tested in a proton beam at the COSY accelerator at Forschungszentrum Jülich. The different layouts are compared in terms of most probable pulse height, detection efficiency and noise behaviour as well as timing resolution. The spatial distributions of these properties across the scintillator surface are presented. The best layout can be operated at a mean efficiency of bar epsilon=99.9 % while sustaining low noise rates in the order of 10 Hz with a timing resolution of less than 3 ns. Both efficiency and timing resolution show good spatial homogeneity.

  3. Time multiplexing super resolution using a 2D Barker-based array

    NASA Astrophysics Data System (ADS)

    Ilovitsh, Asaf; Ilovitsh, Tali; Preter, Eyal; Levanon, Nadav; Zalevsky, Zeev

    2016-03-01

    We propose the use of a two dimensional Barker-based array in order to improve the performance of the standard time multiplexing super resolution system. The Barker-based array is a 2D generalization of the standard 1D Barker code. It enables achieving a two dimensional super resolution image using only one dimensional scan, by exploiting its unique auto correlation property. A sequence of low resolution images are captured at different lateral positions of the array, and are decoded properly using the same array. In addition, we present the use of a mismatched array for the decoding process. The cross correlation between the Barker-based array and the mismatched array has a perfect peak to sidelobes ratio, making it ideal for the super resolution process. Also, we propose the projection of this array onto the object using a phase-only spatial light modulator. Projecting the array eliminates the need for printing it, mechanically shifting it, and having a direct contact with the object, which is not feasible in many imaging applications. The proposed method is presented analytically, demonstrated via numerical simulation, and validated by laboratory experiments.

  4. Active imaging lens with real-time variable resolution and constant field of view

    NASA Astrophysics Data System (ADS)

    Parent, Jocelyn; Thibault, Simon

    2010-08-01

    We present a lens with a constant total field of view and real-time variable resolution in certain zones of interest. This smart imaging lens uses an active optical element to modify as desired the local distortion. This way, while keeping the total field of view constant, the resolution can be increased in a zone of interest, at the expense of decreasing it somewhere in the remaining part of the field of view. We first present the concept of this lens, using a deformable mirror as the active surface. Computer simulations are done with Zemax in which a magnifying power of 2 in a zone of interest representing 10% of the full field of view is achieved, using a f=12.5 mm lens and a F/# of 18. Different combinations of theses parameters would allow different performances and results. We then present experimental results of this lens with a prototype built using a ferrofluidic deformable mirror as the active element. Experimental results of a zone of increased resolution with a magnification of 1.32 and a zone of decreased resolution with a magnification of 0.80 are obtained.

  5. In-depth study of single photon time resolution for the Philips digital silicon photomultiplier

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Gundacker, S.; Pizzichemi, M.; Ghezzi, A.; Auffray, E.; Lecoq, P.; Paganoni, M.

    2016-06-01

    The digital silicon photomultiplier (SiPM) has been commercialised by Philips as an innovative technology compared to analog silicon photomultiplier devices. The Philips digital SiPM, has a pair of time to digital converters (TDCs) connected to 12800 single photon avalanche diodes (SPADs). Detailed measurements were performed to understand the low photon time response of the Philips digital SiPM. The single photon time resolution (SPTR) of every single SPAD in a pixel consisting of 3200 SPADs was measured and an average value of 85 ps full width at half maximum (FWHM) was observed. Each SPAD sends the signal to the TDC with different signal propagation time, resulting in a so called trigger network skew. This distribution of the trigger network skew for a pixel (3200 SPADs) has been measured and a variation of 50 ps FWHM was extracted. The SPTR of the whole pixel is the combination of SPAD jitter, trigger network skew, and the SPAD non-uniformity. The SPTR of a complete pixel was 103 ps FWHM at 3.3 V above breakdown voltage. Further, the effect of the crosstalk at a low photon level has been studied, with the two photon time resolution degrading if the events are a combination of detected (true) photons and crosstalk events. Finally, the time response to multiple photons was investigated.

  6. A High Resolution, Multi-stop, Time-to-Digital Converter for Nuclear Time-of-Flight Measurements

    SciTech Connect

    D. F. Spencer; J. Cole; M. Drigert; R. Aryaeinejad

    2006-01-01

    A high-resolution, multi-stop, time-to-digital converter (TDC) was designed and developed to precisely measure the times-of-flight (TOF) of incident neutrons responsible for induced fission and capture reactions on actinide targets. The minimum time resolution is ±1 ns. The TDC design was implemented into a single, dual-wide CAMAC module. The CAMAC bus is used for command and control as well as an alternative data output. A high-speed ECL interface, compatible with LeCroy FERA modules, was also provided for the principle data output path. An Actel high-speed field programmable gate array (FPGA) chip was incorporated with an external oscillator and an internal multiple clock phasing system. This device implemented the majority of the high-speed register functions, the state machine for the FERA interface, and the high-speed counting circuit used for the TDC conversion. An external microcontroller was used to monitor and control system-level changes. In this work we discuss the performance of this TDC module as well as its application.

  7. Improved-resolution real-time skin-dose mapping for interventional fluoroscopic procedures

    NASA Astrophysics Data System (ADS)

    Rana, Vijay K.; Rudin, Stephen; Bednarek, Daniel R.

    2014-03-01

    We have developed a dose-tracking system (DTS) that provides a real-time display of the skin-dose distribution on a 3D patient graphic during fluoroscopic procedures. Radiation dose to individual points on the skin is calculated using exposure and geometry parameters from the digital bus on a Toshiba C-arm unit. To accurately define the distribution of dose, it is necessary to use a high-resolution patient graphic consisting of a large number of elements. In the original DTS version, the patient graphics were obtained from a library of population body scans which consisted of larger-sized triangular elements resulting in poor congruence between the graphic points and the x-ray beam boundary. To improve the resolution without impacting real-time performance, the number of calculations must be reduced and so we created software-designed human models and modified the DTS to read the graphic as a list of vertices of the triangular elements such that common vertices of adjacent triangles are listed once. Dose is calculated for each vertex point once instead of the number of times that a given vertex appears in multiple triangles. By reformatting the graphic file, we were able to subdivide the triangular elements by a factor of 64 times with an increase in the file size of only 1.3 times. This allows a much greater number of smaller triangular elements and improves resolution of the patient graphic without compromising the real-time performance of the DTS and also gives a smoother graphic display for better visualization of the dose distribution.

  8. Time-Resolved, Atomic-Resolution Imaging of Metastable Atom Configurations

    NASA Astrophysics Data System (ADS)

    Kisielowski, Christian

    2013-03-01

    In the recent past significant initiatives are dedicated to the exploration of sustainable energy solutions. Certainly, related research must address a rich diversity of challenges because it is not only the static arrangement of matter that must be understood at a single atom level but also the collective behavior of molecular assemblies that leads to functionality. Moreover, hybrid materials are commonly employed that contain hard and soft matter components to artificially stimulate complex behavior. Electron microscopy is often considered a method of choice that may address these challenges if further improved. This paper reports on the development of in-line holography for atomic-resolution electron microscopy, which makes use of dose rates as low as a few atto Amperes per square Ångstrom and of variable acceleration voltages between 20 kV and 300 kV. The approach allows for enhancing resolution in radiation sensitive materials and is especially well suited to study the time evolution of nanoscale objects with single atom sensitivity. For the first time temporary displacements of single atoms from their equilibrium lattice sites into metastable sites across a projected distance of only 0.07 nm and 0.10 nm are directly captured in images with a time resolution around one second. These temporary excitations seem relevant to the irreversible transformation of graphene into carbene and to self-diffusion in catalysts. In suitable experimental conditions, however, atom displacements of 0.05 - 0.1 nm are entirely reversible. Exploiting the reversible nature of such excitations, it may become feasible to probe for conformational object changes in beam sensitive materials at improved spatial resolution. This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231

  9. High-time resolution of the low-latitude asymmetric disturbance in the geomagnetic field.

    NASA Technical Reports Server (NTRS)

    Crooker, N. U.

    1972-01-01

    The low-latitude asymmetric disturbance field is investigated by means of a Fourier harmonic analysis performed on 2.5-min interspaced values of magnetic records from eight stations, in lieu of the hourly values used in Crooker and Siscoe's (1971) study. The major advantage of the higher time resolution is that substorm activity, which has a time scale of 1-2 hr, can be studied in detail. Data covering four active periods in 1965 and five active periods in 1967 are used.

  10. Expected resolution and detectability of adenocarcinoma tumors within human breast in time-resolved images

    NASA Astrophysics Data System (ADS)

    Gandjbakhche, Amir H.; Nossal, Ralph J.; Dadmarz, Roya; Schwartzentruber, Douglas; Bonner, Robert F.

    1995-04-01

    The prospects for time-resolved optical mammography rests on the ability to detect adenocarcinoma within the breast with sufficient resolution and specificity to compete with X-ray mammography. We characterized the optical properties of an unusually large (6 cm diameter) fresh adenocarcinoma and normal breast tissue (determined by histology to be predominantly adipose tissue) obtained from a patient undergoing mastectomy. Large specimens (5 mm thick and 3 cm wide) allowed the determination of absorption and scattering coefficients and their spatial heterogeneity as probed with a 1 mm diameter laser beam at 633 nm and 800 nm utilizing total reflectance and transmittance measure with integrating spheres. The difference between scattering coefficients of the malignant tumor and those of normal (principally adipose) breast tissue at 633 nm was much greater than the heterogeneity within each sample. This scattering difference is the principal source of contrast, particularly in time-resolved images. However, the high scattering coefficient of normal breast tissue at 633 nm limits the practicality of time-resolved mammography of a human breast compressed to 5 cm. Although the scattering coefficient of the normal breast tissue decreases at 800 nm, the differences between the optical properties of normal and abnormal breast tissue also are reduced. We used these empirical results in theoretical expressions obtained from random walk theory to quantify the expected resolution, contrast, and the detected intensity of 3, 6, and 9 mm tumors within otherwise homogeneous human breasts as a function of the gating-time of time-resolved optical mammography.

  11. Automated time-lapse microscopy and high-resolution tracking of cell migration

    SciTech Connect

    Fotos, Joseph S.; Vivek, Patel P.; Karin, Norm J.; Temburni, Murali; Koh, John T.; Galileo, Deni S.

    2006-08-09

    The study of cell motility is greatly enhanced by using a fully-automated high-throughput time-lapse microscopy system that is capable of collecting and analyzing data (1) from closely-spaced time points (seconds to minutes), (2) over long periods (hours to days), (3) from multiple areas of interest, (4) under several different experimental conditions simultaneously. Time-lapse video images collected under phase contrast and fluorescent illumination were analyzed using parameters of migration velocity, total accumulated distance (path length), and directionality for individual cells or for averaged cell populations. Quantitation of ''scratch'' or ''wound healing'' assays revealed unique motility dynamics of drug-treated and adhesion molecule-transfected cells with high resolution and, thus, is a vast distinct improvement of current methods. Several fluorescent vital labeling methods commonly used for end-point analyses, including GFP expression, were evaluated and most were useful for time-lapse studies under specific conditions. For example, fluorescently-labeled tumor cells were seeded onto cell monolayers expressing ectopic adhesion molecules displayed altered migration velocities compared to tumor cells plated directly onto culture dishes. The techniques described here revealed cell motility behavior not discernable by previously-used methods. We propose that quantitative time-lapse video analysis will foster the creation new cell motility assays, and increase the resolution and accuracy of existing assays.

  12. Ultra-Wideband Time-Difference-of-Arrival High Resolution 3D Proximity Tracking System

    NASA Technical Reports Server (NTRS)

    Ni, Jianjun; Arndt, Dickey; Ngo, Phong; Phan, Chau; Dekome, Kent; Dusl, John

    2010-01-01

    This paper describes a research and development effort for a prototype ultra-wideband (UWB) tracking system that is currently under development at NASA Johnson Space Center (JSC). The system is being studied for use in tracking of lunar./Mars rovers and astronauts during early exploration missions when satellite navigation systems are not available. U IATB impulse radio (UWB-IR) technology is exploited in the design and implementation of the prototype location and tracking system. A three-dimensional (3D) proximity tracking prototype design using commercially available UWB products is proposed to implement the Time-Difference- Of-Arrival (TDOA) tracking methodology in this research effort. The TDOA tracking algorithm is utilized for location estimation in the prototype system, not only to exploit the precise time resolution possible with UWB signals, but also to eliminate the need for synchronization between the transmitter and the receiver. Simulations show that the TDOA algorithm can achieve the fine tracking resolution with low noise TDOA estimates for close-in tracking. Field tests demonstrated that this prototype UWB TDOA High Resolution 3D Proximity Tracking System is feasible for providing positioning-awareness information in a 3D space to a robotic control system. This 3D tracking system is developed for a robotic control system in a facility called "Moonyard" at Honeywell Defense & System in Arizona under a Space Act Agreement.

  13. Towards real-time simulation of cardiac electrophysiology in a human heart at high resolution.

    PubMed

    Richards, David F; Glosli, James N; Draeger, Erik W; Mirin, Arthur A; Chan, Bor; Fattebert, Jean-Luc; Krauss, William D; Oppelstrup, Tomas; Butler, Chris J; Gunnels, John A; Gurev, Viatcheslav; Kim, Changhoan; Magerlein, John; Reumann, Matthias; Wen, Hui-Fang; Rice, John Jeremy

    2013-01-01

    We have developed the capability to rapidly simulate cardiac electrophysiological phenomena in a human heart discretised at a resolution comparable with the length of a cardiac myocyte. Previous scientific investigation has generally invoked simplified geometries or coarse-resolution hearts, with simulation duration limited to 10s of heartbeats. Using state-of-the-art high-performance computing techniques coupled with one of the most powerful computers available (the 20 PFlop/s IBM BlueGene/Q at Lawrence Livermore National Laboratory), high-resolution simulation of the human heart can now be carried out over 1200 times faster compared with published results in the field. We demonstrate the utility of this capability by simulating, for the first time, the formation of transmural re-entrant waves in a 3D human heart. Such wave patterns are thought to underlie Torsades de Pointes, an arrhythmia that indicates a high risk of sudden cardiac death. Our new simulation capability has the potential to impact a multitude of applications in medicine, pharmaceuticals and implantable devices.

  14. Temperature-resolution anomalies in the reconstruction of time dynamics from energy-loss experiments

    NASA Astrophysics Data System (ADS)

    Kogar, Anshul; Vig, Sean; Gan, Yu; Abbamonte, Peter

    2014-06-01

    Inelastic scattering techniques provide a powerful approach to studying electron and nuclear dynamics, via reconstruction of a propagator that quantifies the time evolution of a system. There is now growing interest in applying such methods to very low energy excitations, such as lattice vibrations, but in this limit the cross section is no longer proportional to a propagator. Significant deviations occur due to the finite temperature Bose statistics of the excitations. Here we consider this issue in the context of high-resolution electron energy-loss experiments on the copper-oxide superconductor Bi2Sr2CaCu2O8. We find that simple division of a Bose factor yields an accurate propagator on energy scales greater than the resolution width. However, at low energy scales, the effects of resolution and finite temperature conspire to create anomalies in the dynamics at long times. We compare two practical ways for dealing with such anomalies, and discuss the range of validity of the technique in light of this comparison.

  15. An Error Model for High-Time Resolution Satellite Precipitation Products

    NASA Astrophysics Data System (ADS)

    Maggioni, V.; Sapiano, M.; Adler, R. F.; Huffman, G. J.; Tian, Y.

    2013-12-01

    A new error scheme (PUSH: Precipitation Uncertainties for Satellite Hydrology) is presented to provide global estimates of errors for high time resolution, merged precipitation products. Errors are estimated for the widely used Tropical Rainfall Monitoring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) 3B42 product at daily/0.25° resolution, using the high quality NOAA CPC-UNI gauge analysis as the benchmark. Each of the following four scenarios is explored and explicitly modeled: correct no-precipitation detection (both satellite and gauges detect no precipitation), missed precipitation (satellite records a zero, but it is incorrect), false alarm (satellite detects precipitation, but the reference is zero), and hit (both satellite and gauges detect precipitation). Results over Oklahoma show that the estimated probability distributions are able to reproduce the probability density functions of the benchmark precipitation, in terms of both expected values and quantiles. PUSH adequately captures missed precipitation and false detection uncertainties, reproduces the spatial pattern of the error, and shows a good agreement between observed and estimated errors. The resulting error estimates could be attached to the standard products for the scientific community to use. Investigation is underway to: 1) test the approach in different regions of the world; 2) verify the ability of the model to discern the systematic and random components of the error; 3) and evaluate the model performance when higher time-resolution satellite products (i.e., 3-hourly) are employed.

  16. Time-frequency model for echo-delay resolution in wideband biosonar.

    PubMed

    Neretti, Nicola; Sanderson, Mark I; Intrator, Nathan; Simmons, James A

    2003-04-01

    A time/frequency model of the bat's auditory system was developed to examine the basis for the fine (approximately 2 micros) echo-delay resolution of big brown bats (Eptesicus fuscus), and its performance at resolving closely spaced FM sonar echoes in the bat's 20-100-kHz band at different signal-to-noise ratios was computed. The model uses parallel bandpass filters spaced over this band to generate envelopes that individually can have much lower bandwidth than the bat's ultrasonic sonar sounds and still achieve fine delay resolution. Because fine delay separations are inside the integration time of the model's filters (approximately 250-300 micros), resolving them means using interference patterns along the frequency dimension (spectral peaks and notches). The low bandwidth content of the filter outputs is suitable for relay of information to higher auditory areas that have intrinsically poor temporal response properties. If implemented in fully parallel analog-digital hardware, the model is computationally extremely efficient and would improve resolution in military and industrial sonar receivers.

  17. High-time resolution measurements of solar wind heavy ions with SOHO/CELIAS/CTOF

    NASA Astrophysics Data System (ADS)

    Janitzek, N. P.; Taut, A.; Berger, L.; Bochsler, P.; Drews, C.; Klecker, B.; Wimmer-Schweingruber, R. F.

    2016-03-01

    The Charge Time-Of-Flight (CTOF) mass spectrometer as part of the Charge, ELement and Isotope Analysis System (CELIAS) onboard the SOlar and Heliospheric Observatory (SOHO) is designed to measure the kinetic properties and elemental/ionic composition of solar wind ions heavier than protons, which we refer to as heavy ions. This is achieved by the combined measurements of the energy-per-charge, the time-of-flight and the energy of incident ions. The CTOF instrument combines a remarkable time-of-flight resolution with a large effective area and a high measurement cadence. This allows to determine the Velocity Distribution Functions (VDFs) of a wide range of heavy ions with 5-minute time resolution which ensures that the complete VDF is measured under nearly identical solar wind and magnetic field conditions. For the measurement period between Day Of Year (DOY) 150 and 220 in 1996, which covers a large part of the instrument's short life time, we analyzed VDFs of solar wind iron Fe8+, Fe9+ and Fe10+ for differential streaming relative to the solar wind proton speed measured simultaneously with the CELIAS Proton Monitor (PM). We find an increasing differential streaming with increasing solar wind proton speed for all investigated ions up to ion-proton velocity differences of 30 - 50 km s-1 at proton velocities of 500 km s-1, which is contradictory to an earlier CTOF study by [7]. We believe this difference is because in this study we used raw Pulse Height Analysis (PHA) data with a significantly increased mass and mass-per-charge resolution compared to the earlier used onboard preprocessed data.

  18. Estimation of grassland use intensities based on high spatial resolution LAI time series

    NASA Astrophysics Data System (ADS)

    Asam, S.; Klein, D.; Dech, S.

    2015-04-01

    The identification and surveillance of agricultural management and the measurement of biophysical canopy parameters in grasslands is relevant for environmental protection as well as for political and economic reasons, as proper grassland management is partly subsidized. An ideal monitoring tool is remote sensing due to its area wide continuous observations. However, due to small-scaled land use patterns in many parts of central Europe, a high spatial resolution is needed. In this study, the feasibility of RapidEye data to derive leaf area index (LAI) time series and to relate them to grassland management practices is assessed. The study area is the catchment of river Ammer in southern Bavaria, where agricultural areas are mainly grasslands. While extensively managed grasslands are maintained with one to two harvests per year and no or little fertilization, intensive cultivation practices compass three to five harvests per year and turnover pasturing. Based on a RapidEye time series from 2011 with spatial resolution of 6.5 meters, LAI is derived using the inverted radiation transfer model PROSAIL. The LAI in this area ranges from 1.5 to 7.5 over the vegetation period and is estimated with an RMSE between 0.7 and 1.1. The derived LAI maps cover 85 % of the study area's grasslands at least seven times. Using statistical metrics of the LAI time series, different grassland management types can be identified: very intensively managed meadows, intensively managed meadows, intensively managed pastures, and extensively managed meadows and moor. However, a precise identification of the mowing dates highly depends on the coincidence with satellite data acquisitions. Further analysis should focus therefor on the selection of the temporal resolution of the time series as well as on the performance of further vegetation parameters and indices compared to LAI.

  19. Low time resolution analysis of polar ice cores cannot detect impulsive nitrate events

    NASA Astrophysics Data System (ADS)

    Smart, D. F.; Shea, M. A.; Melott, A. L.; Laird, C. M.

    2014-12-01

    Ice cores are archives of climate change and possibly large solar proton events (SPEs). Wolff et al. (2012) used a single event, a nitrate peak in the GISP2-H core, which McCracken et al. (2001a) time associated with the poorly quantified 1859 Carrington event, to discredit SPE-produced, impulsive nitrate deposition in polar ice. This is not the ideal test case. We critique the Wolff et al. analysis and demonstrate that the data they used cannot detect impulsive nitrate events because of resolution limitations. We suggest reexamination of the top of the Greenland ice sheet at key intervals over the last two millennia with attention to fine resolution and replicate sampling of multiple species. This will allow further insight into polar depositional processes on a subseasonal scale, including atmospheric sources, transport mechanisms to the ice sheet, postdepositional interactions, and a potential SPE association.

  20. Improving resolution of crosswell seismic section based on time-frequency analysis

    SciTech Connect

    Luo, H.; Li, Y.

    1994-12-31

    According to signal theory, to improve resolution of seismic section is to extend high-frequency band of seismic signal. In cross-well section, sonic log can be regarded as a reliable source providing high-frequency information to the trace near the borehole. In such case, what to do is to introduce this high-frequency information into the whole section. However, neither traditional deconvolution algorithms nor some new inversion methods such as BCI (Broad Constraint Inversion) are satisfied because of high-frequency noise and nonuniqueness of inversion results respectively. To overcome their disadvantages, this paper presents a new algorithm based on Time-Frequency Analysis (TFA) technology which has been increasingly received much attention as an useful signal analysis too. Practical applications show that the new method is a stable scheme to improve resolution of cross-well seismic section greatly without decreasing Signal to Noise Ratio (SNR).

  1. New high-resolution electrostatic ion mass analyzer using time of flight

    NASA Technical Reports Server (NTRS)

    Hamilton, D. C.; Gloeckler, G.; Ipavich, F. M.; Lundgren, R. A.; Sheldon, R. B.

    1990-01-01

    The design of a high-resolution ion-mass analyzer is described, which is based on an accurate measurement of the time of flight (TOF) of ions within a region configured to produce a harmonic potential. In this device, the TOF, which is independent of ion energy, is determined from a start pulse from secondary electrons produced when the ion passes through a thin carbon foil at the entrance of the TOF region and at a stop pulse from the ion striking a microchannel plate upon exciting the region. A laboratory prototype instrument called 'VMASS' was built and was tested at the Goddard Space Flight Center electrostatic accelerator, showing a good mass resolution of the instrument. Sensors of the VMASS type will form part of the WIND Solar Wind and Suprathermal Ion experiment, the Soho mission, and the Advanced Composition Explorer.

  2. A digital approach for real time high-rate high-resolution radiation measurements

    NASA Astrophysics Data System (ADS)

    Gerardi, G.; Abbene, L.

    2014-12-01

    Modern spectrometers are currently developed by using digital pulse processing (DPP) systems, showing several advantages over traditional analog electronics. The aim of this work is to present digital strategies, in a time domain, for the development of real time high-rate high-resolution spectrometers. We propose a digital method, based on the single delay line (SDL) shaping technique, able to perform multi-parameter analysis with high performance even at high photon counting rates. A robust pulse shape and height analysis (PSHA), applied on single isolated time windows of the detector output waveforms, is presented. The potentialities of the proposed strategy are highlighted through both theoretical and experimental approaches. To strengthen our approach, the implementation of the method on a real-time system together with some experimental results are presented. X-ray spectra measurements with a semiconductor detector are performed both at low and high photon counting rates (up to 1.1 Mcps).

  3. High-resolution distributed temperature sensing with the multiphoton-timing technique

    NASA Astrophysics Data System (ADS)

    Höbel, M.; Ricka, J.; Wüthrich, M.; Binkert, Th.

    1995-06-01

    We report on a multiphoton-timing distributed temperature sensor (DTS) based on the concept of distributed anti-Stokes Raman thermometry. The sensor combines the advantage of very high spatial resolution (40 cm) with moderate measurement times. In 5 min it is possible to determine the temperature of as many as 4000 points along an optical fiber with an accuracy Delta T less than 2 deg C. The new feature of the DTS system is the combination of a fast single-photon avalanche diode with specially designed real-time signal-processing electronics. We discuss various parameters that affect the operation of analog and photon-timing DTS systems. Particular emphasis is put on the consequences of the nonideal behavior of sensor components and the corresponding correction procedures.

  4. Time resolution dependence of information measures for spiking neurons: scaling and universality

    PubMed Central

    Marzen, Sarah E.; DeWeese, Michael R.; Crutchfield, James P.

    2015-01-01

    The mutual information between stimulus and spike-train response is commonly used to monitor neural coding efficiency, but neuronal computation broadly conceived requires more refined and targeted information measures of input-output joint processes. A first step toward that larger goal is to develop information measures for individual output processes, including information generation (entropy rate), stored information (statistical complexity), predictable information (excess entropy), and active information accumulation (bound information rate). We calculate these for spike trains generated by a variety of noise-driven integrate-and-fire neurons as a function of time resolution and for alternating renewal processes. We show that their time-resolution dependence reveals coarse-grained structural properties of interspike interval statistics; e.g., τ-entropy rates that diverge less quickly than the firing rate indicated by interspike interval correlations. We also find evidence that the excess entropy and regularized statistical complexity of different types of integrate-and-fire neurons are universal in the continuous-time limit in the sense that they do not depend on mechanism details. This suggests a surprising simplicity in the spike trains generated by these model neurons. Interestingly, neurons with gamma-distributed ISIs and neurons whose spike trains are alternating renewal processes do not fall into the same universality class. These results lead to two conclusions. First, the dependence of information measures on time resolution reveals mechanistic details about spike train generation. Second, information measures can be used as model selection tools for analyzing spike train processes. PMID:26379538

  5. Flood and Landslide Applications of High Time Resolution Satellite Rain Products

    NASA Technical Reports Server (NTRS)

    Adler, Robert F.; Hong, Yang; Huffman, George J.

    2006-01-01

    Experimental, potentially real-time systems to detect floods and landslides related to heavy rain events are described. A key basis for these applications is high time resolution satellite rainfall analyses. Rainfall is the primary cause for devastating floods across the world. However, in many countries, satellite-based precipitation estimation may be the best source of rainfall data due to insufficient ground networks and absence of data sharing along many trans-boundary river basins. Remotely sensed precipitation from the NASA's TRMM Multi-satellite Precipitation Analysis (TMPA) operational system (near real-time precipitation at a spatial-temporal resolution of 3 hours and 0.25deg x 0.25deg) is used to monitor extreme precipitation events. Then these data are ingested into a macro-scale hydrological model which is parameterized using spatially distributed elevation, soil and land cover datasets available globally from satellite remote sensing. Preliminary flood results appear reasonable in terms of location and frequency of events, with implementation on a quasi-global basis underway. With the availability of satellite rainfall analyses at fine time resolution, it has also become possible to assess landslide risk on a near-global basis. Early results show that landslide occurrence is closely associated with the spatial patterns and temporal distribution of TRMM rainfall characteristics. Particularly, the number of landslides triggered by rainfall is related to rainfall climatology, antecedent rainfall accumulation, and intensity-duration of rainstorms. For the purpose of prediction, an empirical TMPA-based rainfall intensity-duration threshold is developed and shown to have skill in determining potential areas of landslides. These experimental findings, in combination with landslide surface susceptibility information based on satellite-based land surface information, form a starting point towards a potential operational landslide monitoring/warning system

  6. The Crab pulsar in the visible and ultraviolet with 20 microsecond effective time resolution

    NASA Technical Reports Server (NTRS)

    Percival, J. W.; Biggs, J. D.; Dolan, J. F.; Robinson, E. L.; Taylor, M. J.; Bless, R. C.; Elliot, J. L.; Nelson, M. J.; Ramseyer, T. F.; Van Citters, G. W.

    1993-01-01

    Observations of PSR 0531+21 with the High Speed Photometer on the HST in the visible in October 1991 and in the UV in January 1992 are presented. The time resolution of the instrument was 10.74 microsec; the effective time resolution of the light curves folded modulo the pulsar period was 21.5 microsec. The main pulse arrival time is the same in the UV as in the visible and radio to within the accuracy of the establishment of the spacecraft clock, +/- 1.05 ms. The peak of the main pulse is resolved in time. Corrected for reddening, the intensity spectral index of the Crab pulsar from 1680 to 7400 A is 0.11 +/- 0.13. The pulsed flux has an intensity less than 0.9 percent of the peak flux just before the onset of the main pulse. The variations in intensity of individual main and secondary pulses are uncorrelated, even within the same rotational period.

  7. On high time-range resolution observations of PMSE: Statistical characteristics

    NASA Astrophysics Data System (ADS)

    Sommer, Svenja; Chau, Jorge L.; Schult, Carsten

    2016-06-01

    We present observations of polar mesospheric summer echoes (PMSE) with an unprecedented temporal sampling of 2 ms and range resolution down to 75 m. On these time and spatial scales, PMSE exhibit features, like correlation in time and range, that have not been described before. To characterize our high resolution observations, we provide a 4-D statistical model, based on random processes. In this way we can distinguish between geophysical and instrumental effects on our measurements. In our simulations, PMSE is statistically characterized in frequency, angular space, and inverse altitude. With this model, we are able to reproduce our observations on a statistical basis and estimate the intrinsic spectral width of PMSE. For chosen data sets, such values range between 0.5 Hz and 4 Hz (1.4 ms-1 to 11.2 ms-1). Furthermore, we show that apparent oscillations in time and an apparent high speed motion of the mean scattering center are just representations of the random nature of PMSE measurements on short time scales.

  8. Automated time-lapse microscopy and high-resolution tracking of cell migration.

    PubMed

    Fotos, Joseph S; Patel, Vivek P; Karin, Norman J; Temburni, Murali K; Koh, John T; Galileo, Deni S

    2006-05-01

    We describe a novel fully automated high-throughput time-lapse microscopy system and evaluate its performance for precisely tracking the motility of several glioma and osteoblastic cell lines. Use of this system revealed cell motility behavior not discernable with conventional techniques by collecting data (1) from closely spaced time points (minutes), (2) over long periods (hours to days), (3) from multiple areas of interest, (4) in parallel under several different experimental conditions. Quantitation of true individual and average cell velocity and path length was obtained with high spatial and temporal resolution in "scratch" or "wound healing" assays. This revealed unique motility dynamics of drug-treated and adhesion molecule-transfected cells and, thus, this is a considerable improvement over current methods of measurement and analysis. Several fluorescent vital labeling methods commonly used for end-point analyses (GFP expression, DiO lipophilic dye, and Qtracker nanocrystals) were found to be useful for time-lapse studies under specific conditions that are described. To illustrate one application, fluorescently labeled tumor cells were seeded onto cell monolayers expressing ectopic adhesion molecules, and this resulted in consistently reduced tumor cell migration velocities. These highly quantitative time-lapse analysis methods will promote the creation of new cell motility assays and increase the resolution and accuracy of existing assays.

  9. STS-48 Upper Atmosphere Research Satellite (UARS) is released by OV-103's RMS

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The Upper Atmosphere Research Satellite (UARS) is released by the remote manipulator system (RMS) end effector and moves away into the blackness of space. During STS-48 deployment, the RMS lower arm boom, wrist pitch joint, and end effector are seen in the foreground. On UARS, the grapple fixture (center), the Microwave Limb Sounder (MLS) spectrometer (left of RMS), the Cryogenic Limb Array Etalon Spectrometer (on top above grapple fixture), the Particle Environment Monitor (PEM) Zenith Energetic Particle System (ZEPS) (right), and the PEM Nadir Energetic Particle System (NEPS) magnetometer (bottom right) are visible.

  10. Remote Manipulator System (RMS)-based Controls-Structures Interaction (CSI) flight experiment feasibility study

    NASA Technical Reports Server (NTRS)

    Demeo, Martha E.

    1990-01-01

    The feasibility of an experiment which will provide an on-orbit validation of Controls-Structures Interaction (CSI) technology, was investigated. The experiment will demonstrate the on-orbit characterization and flexible-body control of large flexible structure dynamics using the shuttle Remote Manipulator System (RMS) with an attached payload as a test article. By utilizing existing hardware as well as establishing integration, operation and safety algorithms, techniques and procedures, the experiment will minimize the costs and risks of implementing a flight experiment. The experiment will also offer spin-off enhancement to both the Shuttle RMS (SRMS) and the Space Station RMS (SSRMS).

  11. The time of resolution and the rate of recurrence in acute central serous chorioretinopathy following spontaneous resolution and low-fluence photodynamic therapy: a case-control study.

    PubMed

    Ozkaya, A; Alkin, Z; Ozveren, M; Yazici, A T; Taskapili, M

    2016-07-01

    PurposeTo evaluate the resolution time and the recurrence rate of acute central serous chorioretinopathy (CSC) after spontaneous resolution and low-fluence photodynamic therapy (PDT).MethodsCase-control study: The CSC patients who were admitted to our clinic for the first time were included. No treatment was given during the first 6 months. Patients were treated with PDT after 6 months from the initial signs of the disease, if they did not show any sign of resolution. The patients who showed a significant decrease in subretinal fluid after month 6 were not scheduled for PDT. The primary outcomes were the resolution time and the recurrence rate after the first episode. Secondary outcome measures were the change in BCVA and CRT during the follow up.ResultsA total of 77 consecutive eyes of 77 patients were included, 41 eyes (53.2%) with spontaneously resolved CSC and 36 eyes (46.8%) with PDT-treated CSC. The initial resolution time was 4.1±3.2 months in spontaneous resolution group, and 8.1±0.8 months in PDT group, respectively (P<0.001). The recurrence rate was 51.2% in spontaneous resolution group, and 25% in PDT group (P=0.01). The change in BCVA from baseline to the last follow-up visit was statistically significant in both groups (P=0.002, P=0.003, respectively). The change in CRT from baseline to the last follow up was also statistically significant in both groups (P=0.002, P=0.003, respectively).ConclusionsThe recurrence rate of acute CSC was lower in PDT-treated patients than the spontaneously resolved patients.

  12. High-resolution time-lapse tomography of rat vertebrae during compressive loading: deformation response analysis

    NASA Astrophysics Data System (ADS)

    Fíla, T.; Kytýř, D.; Zlámal, P.; Kumpová, I.; Doktor, T.; Koudelka, P.; Jiroušek, O.

    2014-05-01

    This paper is focused on investigation of mechanical properties of rat vertebrae during compressive loading in the longitudinal direction of rat's spine. High-resolution time-lapse micro-tomography was used as a tool to create models of the inner structure and deformed shape in pre-defined deformation steps. First, peripheral areas of vertebra specimen were embedded in polymethyl methacrylate to obtain proper boundary conditions of contact between specimen and loading plattens. Experimental loading device designed for application in X-ray setups was utilized to compress the vertebrae in several deformation steps. High-resolution micro-tomography scanning was carried out at each deformation step. Specimen was irradiated in tomography device equipped with microfocus X-ray tube with 5μm focal spot size and large area flat panel detector. Spatial resolution of reconstructed three-dimensional images was approximately 10μm. Digital volume correlation algorithm was utilized in order to assess displacements in the microstructure in every loading increment. Finite element model of vertebra was created from volumetric data reconstructed from tomography of the undeformed specimen. Simulated compressive test of the developed finite element model was performed in order to compare stiffness and displacements obtained by digital volume correlation and finite element simulation.

  13. High-Resolution Time-Lapse Monitoring of Unsaturated Flow using Automated GPR Data Collection

    NASA Astrophysics Data System (ADS)

    Mangel, A. R.; Moysey, S. M.; Lytle, B. A.; Bradford, J. H.

    2015-12-01

    High-resolution ground-penetrating radar (GPR) data provide the detailed information required to image subsurface structures. Recent advances in GPR monitoring now also make it possible to study transient hydrologic processes, but high-speed data acquisition is critical for this application. We therefore highlight the capabilities of our automated system to acquire time-lapse, high-resolution multifold GPR data during infiltration of water into soils. The system design allows for fast acquisition of constant-offset (COP) and common-midpoint profiles (CMP) to monitor unsaturated flow at multiple locations. Qualitative interpretation of the unprocessed COPs can provide substantial information regarding the hydrologic response of the system, such as the complexities of patterns associated with the wetting of the soil and geophysical evidence of non-uniform propagation of a wetting front. While we find that unprocessed images are informative, we show that the spatial variability of velocity introduced by infiltration events can complicate the images and that migration of the data is an effective tool to improve interpretability of the time-lapse images. The ability of the system to collect high density CMP data also introduces the potential for improving the velocity model along with the image via reflection tomography in the post-migrated domain. We show that for both simulated and empirical time-lapse GPR profiles we can resolve a propagating wetting front in the soil that is in good agreement with the response of in-situ soil moisture measurements. The data from these experiments illustrate the importance of high-speed, high-resolution GPR data acquisition for obtaining insight about the dynamics of hydrologic events. Continuing research is aimed at improving the quantitative analysis of surface-based GPR monitoring data for identifying preferential flow in soils.

  14. Manual muscle test at C5 palsy onset predicts the likelihood of and time to C5 palsy resolution.

    PubMed

    Macki, Mohamed; Alam, Ridwan; Kerezoudis, Panagiotis; Gokaslan, Ziya; Bydon, Ali; Bydon, Mohamad

    2016-02-01

    The primary objective of this study was to identify time to and prognostic factors of C5 palsy resolution. All patients over a 7 year period who experienced C5 palsy following a posterior decompression and instrumented fusion surgery were retrospectively reviewed. C5 palsy resolution was defined as a recovery of deltoid muscle function equal to or greater than the preoperative condition as defined by the manual muscle test (MMT). Of the 511 patients who met the selection criteria, 8.6% (n=44) experienced C5 palsy. MMT information was available for 43 patients; 81.4% (n=35) had full resolution from their condition. Of the 35 patients who resolved, the median MMT score at onset was 3-. Following a discrete-time proportional hazards model, the hazards of C5 palsy resolution increased by 19% for every one-grade increase in MMT score at symptom onset (hazard ratio [HR]=1.19, p=0.005). Moreover, males displayed a 71% lower hazard of resolution than females (HR=0.29, p=0.003). Following an adjusted Kaplan-Meier analysis, the median time to C5 palsy resolution was between 6 months and 1 year. In a multiple linear regression, a lower MMT score at the onset of C5 palsy predicted a longer time to C5 palsy resolution (coefficient=-0.19, p=0.003). Time to C5 palsy onset was not statistically associated with hazards of palsy resolution (p=0.381) or time to resolution (p=0.121). A higher MMT score at the onset of C5 palsy statistically significantly predicted a higher chance of resolution and a shorter recovery time. Female sex was also associated with a higher hazard of resolution.

  15. Time-Resolved High-Spatial-Resolution Measurements of Underwater Laser Ionization and Filamentation

    NASA Astrophysics Data System (ADS)

    Jones, Ted; Helle, Mike; Kaganovich, Dmitri; Ting, Antonio; Penano, Joe; Hafizi, Bahman; Chen, Yu-Hsin

    2014-10-01

    Intense underwater laser propagation, filamentation, and ionization are being investigated at NRL for applications including laser-guided discharges, advanced micromachining, and low-frequency laser acoustic generation. Time-resolved spectroscopy of intense underwater propagation and filamentation reveal strong Stimulated molecular Raman Scattering with ps temporal structure and frequency chirp. In addition, fs-time-resolution perpendicular shadowgraph images of ns underwater laser ionization reveal gas microbubble generation throughout the pump beam path. These microbubbles form in ps timescales with remarkably uniform initial diameters of a few-microns. Simulations using the HELCAP 4D nonlinear laser propagation code accurately predict measured filament fluence profiles and propagation, but also indicate complex, time-dependent and axially non-uniform plasma behavior. Results from recent experiments and simulations will be presented. This work is supported by NRL Base Funds.

  16. Electron-optical metrology with femtosecond time resolution (theory and experiment)

    SciTech Connect

    Andreev, S V; Vorob'ev, Nikolai S; Greenfield, D E; Lozovoi, V I; Monastyrskii, M A; Serdyuchenko, Yu N; Smirnov, A V; Shchelev, Mikhail Ya

    2013-04-30

    The principles of simultaneous spatial and temporal focusing of photoelectron beams in nonstationary electric fields are theoretically studied and experimentally realised as applied to time-analysing image-converter tubes (ICTs). It is theoretically shown that the use of nonstationary focusing electric fields makes it possible to surpass the theoretical time resolution limit of ICTs (10{sup -4} s) determined for stationary fields by Zavoisky and Fanchenko in the 40s-50s of the last century. The possibility of forming electron packets with an energy of 10-30 KeV and a subfemtosecond duration (below 10{sup -15} s) gives impetus to the development of time-resolved electron diffraction, which is a direct method of investigation of atomic-molecular dynamics in solid and gaseous media. (extreme light fields and their applications)

  17. Super continuum generation for real time ultrahigh resolution optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Nishizawa, Norihiko; Aguirre, Aaron D.; Fujimoto, James G.

    2006-02-01

    Optical coherence tomography (OCT) is an emerging technology for micrometer-scale, cross-sectional imaging of biological tissue and materials. One of the key limitations to achieving ultrahigh-resolution OCT imaging outside the laboratory setting has been the lack of compact, high-performance broadband light sources with sufficient power and stability to allow practical real-time imaging. The broad-bandwidth supercontinuum (SC) sources were recently demonstrated with femtosecond lasers in combination with nonlinear fibers. Using SC, we can demonstrate ultrahigh resolution OCT. However, wideband SC generally has large excess noise and significant fine structure. Low noise and smooth spectral shape are desired in the ideal supercontinnum source. In this paper, we describe recent studies on practical SC generation for ultrahigh-resolution OCT. SC generation is first analyzed both numerically and experimentally in terms of OCT imaging requirements and optimized conditions for generation are discussed. Supercontinua generated by use of highly nonlinear fiber which have a zero-dispersion wavelength near the pump wavelength, generally result in severe spectral modulation and fluctuating fine structure in the spectra. This spectral modulation produces sidelobes and reduced contrast in the interferometric point-spread function. In contrast, normally dispersive, highly nonlinear fibers (ND-HNFs) can generate smooth and Gaussian shaped supercontinua by the combination of self-phase modulation and normal dispersion. Low noise and wideband SC generation is demonstrated using ND-HNFs. Two colored SC generation is also demonstrated using a photonic crystal fiber which has two close zero dispersion wavelengths. The numerical results are almost in agreement with the experimental ones. Finally, low noise SC generation is demonstrated in an all fiber system based on an ultrashort pulse fiber laser. Wideband, low noise, near Gaussian shaped, high power SC is generated in the 1.55

  18. New ultrarapid-scanning interferometer for FT-IR spectroscopy with microsecond time-resolution

    NASA Astrophysics Data System (ADS)

    Süss, B.; Ringleb, F.; Heberle, J.

    2016-06-01

    A novel Fourier-transform infrared (FT-IR) rapid-scan spectrometer has been developed (patent pending EP14194520.4) which yields 1000 times higher time resolution as compared to conventional rapid-scanning spectrometers. The central element to achieve faster scanning rates is based on a sonotrode whose front face represents the movable mirror of the interferometer. A prototype spectrometer with a time resolution of 13 μs was realized, capable of fully automated long-term measurements with a flow cell for liquid samples, here a photosynthetic membrane protein in solution. The performance of this novel spectrometer is demonstrated by recording the photoreaction of bacteriorhodopsin initiated by a short laser pulse that is synchronized to the data recording. The resulting data are critically compared to those obtained by step-scan spectroscopy and demonstrate the relevance of performing experiments on proteins in solution. The spectrometer allows for future investigations of fast, non-repetitive processes, whose investigation is challenging to step-scan FT-IR spectroscopy.

  19. ns-time resolution for multispecies STED-FLIM and artifact free STED-FCS

    NASA Astrophysics Data System (ADS)

    Koenig, Marcelle; Reisch, Paja; Dowler, Rhys; Kraemer, Benedikt; Tannert, Sebastian; Patting, Matthias; Clausen, Mathias P.; Galiani, Silvia; Eggeling, Christian; Koberling, Felix; Erdmann, Rainer

    2016-03-01

    Stimulated Emission Depletion (STED) Microscopy has evolved into a well established method offering optical superresolution below 50 nm. Running both excitation and depletion lasers in picosecond pulsed modes allows for highest optical resolution as well as fully exploiting the photon arrival time information using time-resolved single photon counting (TCSPC). Non-superresolved contributions can be easily dismissed through time-gated detection (gated STED) or a more detailed fluorescence decay analysis (FLIM-STED), both leading to an even further improved imaging resolution. Furthermore, these methods allow for accurate separation of different fluorescent species, especially if subtle differences in the excitation and emission spectra as well as the fluorescence decay are taken into account in parallel. STED can also be used to shrink the observation volume while studying the dynamics of diffusing species in Fluorescence Correlation Spectroscopy (FCS) to overcome averaging issues along long transit paths. A further unique advantage of STED-FCS is that the observation spot diameter can be tuned in a gradual manner enabling, for example, determining the type of hindered diffusion in lipid membrane studies. Our completely pulsed illumination scheme allows realizing an improved STED-FCS data acquisition using pulsed interleaved excitation (PIE). PIE-STED-FCS allows for a straightforward online check whether the STED laser has an influence on the investigated diffusion dynamics.

  20. A real-time smart sensor for high-resolution frequency estimation in power systems.

    PubMed

    Granados-Lieberman, David; Romero-Troncoso, Rene J; Cabal-Yepez, Eduardo; Osornio-Rios, Roque A; Franco-Gasca, Luis A

    2009-01-01

    Power quality monitoring is a theme in vogue and accurate frequency measurement of the power line is a major issue. This problem is particularly relevant for power generating systems since the generated signal must comply with restrictive standards. The novelty of this work is the development of a smart sensor for real-time high-resolution frequency measurement in accordance with international standards for power quality monitoring. The proposed smart sensor utilizes commercially available current clamp, hall-effect sensor or resistor as primary sensor. The signal processing is carried out through the chirp z-transform. Simulations and experimental results show the efficiency of the proposed smart sensor.

  1. Real-time expert system diagnostics and monitoring for the High Resolution Microwave Survey Targeted Search

    NASA Technical Reports Server (NTRS)

    Macalou, A.; Glass, B. J.

    1993-01-01

    An automated monitoring and diagnostics system (MDS) using virtual real-time software was developed for NASA's High Resolution Microwave Survey (HRMS) Targeted Search System (TSS). The four main tasks required of the MDS were monitoring and recording system health, alerting operators of problems, diagnosing poor system performance, and performing an emergency system shutdown. The MDS was implemented using commercial expert system software tools in addition to interface hardware and software developed on site. The expert system used objects, rules, and schematics in its TSS knowledge representation. The MDS was successfully integrated into the HRMS computer environment, and its performance met or exceeded its requirements.

  2. Steps Toward Real-Time Atmospheric Phase Fluctuation Correction for a High Resolution Radar System

    NASA Astrophysics Data System (ADS)

    Denn, Grant R.; Geldzahler, Barry; Birr, Rick; Brown, Robert; Hoblitzell, Richard; Grant, Kevin; Miller, Michael; Woods, Gary; Archuleta, Arby; Ciminera, Michael; Cornish, Timothy; davarian, faramaz; kocz, jonathan; lee, dennis; Morabito, David Dominic; Soriano, Melissa; Tsao, Philip; Vilnrotter, Victor; Jakeman-Flores, Hali; Ott, melanie; Thomes, W. Joe; Soloff, Jason; NASA Kennedy Space Center, Jet Propulsion Laboratory, NASA Goddard Space Flight Center, NASA Johnson Space Flight Center, Metropolitan State University of Denver

    2016-01-01

    NASA is pursuing a demonstration of coherent uplink arraying at 7.145-7.190 GHz (X-band) and 30-31 GHz (Ka-band) using three 12m diameter COTS antennas separated by 60m at the Kennedy Space Center in Florida, with the goal of a high-power, high-resolution radar array that employs real-time correction for tropospheric phase fluctuation. The major uses for this array will be (a) observations of Near Earth Objects, (b) detection and tracking of orbital debris, (c) high power emergency uplink capability for spacecraft, and (d) radio science experiments.

  3. Real-time fluorescence imaging with 20 nm axial resolution

    PubMed Central

    Stabley, Daniel R.; Oh, Thomas; Simon, Sanford M.; Mattheyses, Alexa L.; Salaita, Khalid

    2015-01-01

    Measuring the nanoscale organization of protein structures near the plasma membrane of live cells is challenging, especially when the structure is dynamic. Here we present the development of a two-wavelength total internal reflection fluorescence method capable of real-time imaging of cellular structure height with nanometre resolution. The method employs a protein of interest tagged with two different fluorophores and imaged to obtain the ratio of emission in the two channels. We use this approach to visualize the nanoscale organization of microtubules and endocytosis of the epidermal growth factor receptor. PMID:26392382

  4. Study of time resolution by digital methods with a DRS4 module

    NASA Astrophysics Data System (ADS)

    Du, Cheng-Ming, Du; Jin-Da, Chen; Xiu-Ling, Zhang; Yang, Hai-Bo; Cheng, Ke; Kong, Jie; Hu, Zheng-Guo; Sun, Zhi-Yu; Su, Hong; Xu, Hu-Shan

    2016-04-01

    A new Digital Pulse Processing (DPP) module has been developed, based on a domino ring sampler version 4 chip (DRS4), with good time resolution for LaBr3 detectors, and different digital timing analysis methods for processing the raw detector signals are reported. The module, composed of an eight channel DRS4 chip, was used as the readout electronics and acquisition system to process the output signals from XP20D0 photomultiplier tubes (PMTs). Two PMTs were coupled with LaBr3 scintillators and placed on opposite sides of a radioactive positron 22Na source for 511 keV γ-ray tests. By analyzing the raw data acquired by the module, the best coincidence timing resolution is about 194.7 ps (FWHM), obtained by the digital constant fraction discrimination (dCFD) method, which is better than other digital methods and analysis methods based on conventional analog systems which have been tested. The results indicate that it is a promising approach to better localize the positron annihilation in positron emission tomography (PET) with time of flight (TOF), as well as for scintillation timing measurement, such as in TOF-ΔE and TOF-E systems for particle identification, with picosecond accuracy timing measurement. Furthermore, this module is more simple and convenient than other systems. Supported by the Science Foundation of the Chinese Academy of Sciences (210340XBO), National Natural Science Foundation of China (11305233,11205222), General Program of National Natural Science Foundation of China (11475234), Specific Fund of National Key Scientific Instrument and Equipment Development Project (2011YQ12009604) and Joint Fund for Research Based on Large-Scale Scientific Facilities (U1532131).

  5. ORFEUSSPAS deployment on RMS prior to release on Flight Day two

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The Orbiting Retrievable Far and Extreme Ultraviolet Spectrometer (ORFEUS) with its Shuttle Pallet Satellite (SPAS) carrier is held on the end of the Remote Manipulator System (RMS) arm prior to its release on Flight Day two.

  6. Reduction of rms-error in shallow faceted large space antennas

    NASA Technical Reports Server (NTRS)

    Fichter, W. B.

    1983-01-01

    This paper examines the potential for reducing root-mean-square surface error in shallow faceted reflectors by replacing flat facets with membrane facets. Exact solutions are obtained for the small lateral deflections of equilateral triangular and rectangular membranes subject to isotropic tension and parabolic edge deflections. These solutions are used to minimize the rms-error between a facet of a shallow paraboloidal surface and its approximating membrane facet. The resulting optimum placements and edge curvatures yield membrane facets which have significantly lower rms-errors than the corresponding best-fit flat facets. The rms-error reductions are about 55 percent for equilateral triangles and 25 percent to 93 percent for rectangles, depending on aspect ratio. The results suggest that the use of membrane facets conforming to curved structural members could yield reflectors with lower rms-error, or comparable error with larger facets and, hence, fewer structural members.

  7. Formula for the rms blur circle radius of Wolter telescope based on aberration theory

    NASA Technical Reports Server (NTRS)

    Shealy, David L.; Saha, Timo T.

    1990-01-01

    A formula for the rms blur circle for Wolter telescopes has been derived using the transverse ray aberration expressions of Saha (1985), Saha (1984), and Saha (1986). The resulting formula for the rms blur circle radius over an image plane and a formula for the surface of best focus based on third-, fifth-, and seventh-order aberration theory predict results in good agreement with exact ray tracing. It has also been shown that one of the two terms in the empirical formula of VanSpeybroeck and Chase (1972), for the rms blur circle radius of a Wolter I telescope can be justified by the aberration theory results. Numerical results are given comparing the rms blur radius and the surface of best focus vs the half-field angle computed by skew ray tracing and from analytical formulas for grazing incidence Wolter I-II telescopes and a normal incidence Cassegrain telescope.

  8. ERP time series with daily and sub-daily resolution determined from CONT05

    NASA Astrophysics Data System (ADS)

    Artz, T.; Böckmann, S.; Nothnagel, A.; Tesmer, V.

    2007-07-01

    From time to time, continuous VLBI campaigns take place under the direction of the IVS. Even though these observations are continuous over two weeks, the standard VLBI analysis procedure leads to independent daily datasets. In this paper, an alternative approach is presented to estimate earth rotation parameters with different temporal resolutions. By stacking the single sessions to a two-weekly solution on the normal equation level, a consistent time series is produced over the whole CONT05 period. Stacked parameters are station positions which are estimated in a 'global' approach and borders of time dependent parameters e.g. zenith wet delay. Analysis of the correlation matrix of estimated parameters gives an impression of the dependencies between them. Furthermore, it is demonstrated how these dependencies depend on the type of datum used. E.g. correlations between earth rotation parameters (ERP) and tropospheric zenith delay of certain VLBI sites have been detected. The ERP time series resulting from the stacking approach turned out to be more consistent over the fortnightly time span. In particular, time series of hourly ERP exhibit a better behaviour at the session boundaries, since the discrepancies at session borders due to poorly determined intervals is minimized.

  9. Real-time flood forecasting with high-resolution NWP rainfall and dual data assimilation

    NASA Astrophysics Data System (ADS)

    Liu, Jia; Bray, Michaela; Han, Dawei

    2014-05-01

    Mesoscale Numerical Weather Prediction (NWP) models are nowadays gaining more and more attention in providing high-resolution rainfall forecasts for real-time flood forecasting. In this study, the newest generation NWP model, Weather Research & Forecasting (WRF) model, is integrated with the rainfall-runoff model in real-time to generate accurate flow forecasts at the catchment scale. The rainfall-runoff model is chosen as the Probability Distribution Model (PDM), which has widely been used for flood forecasting. Dual data assimilation is carried out for real-time updating of the flood forecasting system. The 3-Dimensional Variational (3DVar) data assimilation scheme is incorporated with WRF to assimilate meteorological observations and weather radar reflectivity data in order to improve the WRF rainfall forecasts; meanwhile real-time flow observations are assimilated by the Auto-Regressive Moving Average (ARMA) model to update the forecasted flow transformed by PDM. The Brue catchment located in Southwest England with a drainage area of 135.2 km2 is chosen to be the study area. A dense rain gauge network was set up during a project named HYREX (Hydrological radar experiment), which contains 49 rain gauges and a C-band weather radar, providing with sufficient hydrological and radar data for WRF model verification and data assimilation. Besides the radar reflectivity data, two types of NCAR archived data (SYNOP and SOUND, http://dss.ucar.edu) are also assimilated by 3DVar, which provide real-time surface and upper-level observations of pressure, temperature, humidity and wind from fixed and mobile stations. Four 24 hour storm events are selected from the HYREX project with different characteristics regarding storm formation and rainfall-runoff responses. Real-time flood forecasting is then carried out by the constructed forecasting system for the four storm events with a forecast lead time of 12 hours. The forecasting accuracy of the whole system is found to be

  10. CAD-II: the second version current-mode readout ASIC for high-resolution timing measurements

    NASA Astrophysics Data System (ADS)

    Yuan, Z. X.; Deng, Z.; Wang, Y.; Liu, Y. N.

    2016-07-01

    This paper presents the second version of a fully current-mode front-end ASIC, CAD (Current Amplifier and Discriminator), for MRPC detectors for TOF applications. Several upgrades have been made in this new version, including: 1). Using differential input stages with input impedance down to 30 Ω and LVDS compatible outputs; 2). Much higher current gain and bandwidth of 4.5 A/A and 380 MHz 3). Fabricated in 0.18 μ m CMOS process instead of 0.35 μ m CMOS technology used in CAD-I. The detailed design of the ASIC will be described as well as the measurement results. The single-ended input impedance could be as low as 32 Ω and the power consumption was measured to be 15 mW per channel. Input referred RMS noise current was about 0.56 μ A. The threshold could be set as low as 4.5 μ A referred to input, corresponding to 9 fC for the typical MRPC detector signal with 2 ns width. Sub-10 ps resolution has been measured for input signal above 200 μ A.

  11. An efficient method for calculating RMS von Mises stress in a random vibration environment

    SciTech Connect

    Segalman, D.J.; Fulcher, C.W.G.; Reese, G.M.; Field, R.V. Jr.

    1998-02-01

    An efficient method is presented for calculation of RMS von Mises stresses from stress component transfer functions and the Fourier representation of random input forces. An efficient implementation of the method calculates the RMS stresses directly from the linear stress and displacement modes. The key relation presented is one suggested in past literature, but does not appear to have been previously exploited in this manner.

  12. An efficient method for calculating RMS von Mises stress in a random vibration environment

    SciTech Connect

    Segalman, D.J.; Fulcher, C.W.G.; Reese, G.M.; Field, R.V. Jr.

    1997-12-01

    An efficient method is presented for calculation of RMS von Mises stresses from stress component transfer functions and the Fourier representation of random input forces. An efficient implementation of the method calculates the RMS stresses directly from the linear stress and displacement modes. The key relation presented is one suggested in past literature, but does not appear to have been previously exploited in this manner.

  13. LDEF grappled by remote manipulator system (RMS) during STS-32 retrieval

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This view taken through overhead window W7 on Columbia's, Orbiter Vehicle (OV) 102's, aft flight deck shows the Long Duration Exposure Facility (LDEF) in the grasp of the remote manipulator system (RMS) during STS-32 retrieval activities. Other cameras at eye level were documenting the bus-sized spacecraft at various angles as the RMS manipulated LDEF for a lengthy photo survey. The glaring celestial body in the upper left is the sun with the Earth's surface visible below.

  14. APES: Acute Precipitating Electron Spectrometer -- A high time resolution monodirectional magnetic deflection electron spectrometer

    NASA Astrophysics Data System (ADS)

    Michell, R. G.; Samara, M.; Grubbs, G.; Ogasawara, K.; Miller, G.; Trevino, J. A.; Webster, J.; Stange, J.

    2016-06-01

    We present a description of the Acute Precipitating Electron Spectrometer (APES) that was designed and built for the Ground-to-Rocket Electron Electrodynamics Correlative Experiment (GREECE) auroral sounding rocket mission. The purpose was to measure the precipitating electron spectrum with high time resolution, on the order of milliseconds. The trade-off made in order to achieve high time resolution was to limit the aperture to only one look direction. The energy selection was done by using a permanent magnet to separate the incoming electrons, such that the different energies would fall onto different regions of the microchannel plate and therefore be detected by different anodes. A rectangular microchannel plate (MCP) was used (15 mm × 100 mm), and there was a total of 50 discrete anodes under the MCP, each one 15 mm × 1.5 mm, with a 0.5 mm spacing between anodes. The target energy range of APES was 200 eV to 30 keV.

  15. The High Time Resolution Universe surveys for pulsars and fast transients

    NASA Astrophysics Data System (ADS)

    Keith, Michael J.

    2013-03-01

    The High Time Resolution Universe survey for pulsars and transients is the first truly all-sky pulsar survey, taking place at the Parkes Radio Telescope in Australia and the Effelsberg Radio Telescope in Germany. Utilising multibeam receivers with custom built all-digital recorders the survey targets the fastest millisecond pulsars and radio transients on timescales of 64 μs to a few seconds. The new multibeam digital filter-bank system at has a factor of eight improvement in frequency resolution over previous Parkes multibeam surveys, allowing us to probe further into the Galactic plane for short duration signals. The survey is split into low, mid and high Galactic latitude regions. The mid-latitude portion of the southern hemisphere survey is now completed, discovering 107 previously unknown pulsars, including 26 millisecond pulsars. To date, the total number of discoveries in the combined survey is 135 and 29 MSPs These discoveries include the first magnetar to be discovered by it's radio emission, unusual low-mass binaries, gamma-ray pulsars and pulsars suitable for pulsar timing array experiments.

  16. High time resolution electron measurement by Fast Electron energy Spectrum Analyzer (FESA)

    SciTech Connect

    Saito, Yoshifumi; Fujimoto, Masaki; Maezawa, Kiyoshi; Shinohara, Iku; Tsuda, Yuichi; Sasaki, Shintaro; Kojima, Hirotsugu

    2009-06-16

    We have newly developed an electron energy analyzer FESA (Fast Electron energy Spectrum Analyzer) for a future magnetospheric satellite mission SCOPE. The SCOPE mission is designed in order that observational studies from the cross-scale coupling viewpoint are enabled. One of the key observations necessary for the SCOPE mission is high-time resolution electron measurement. Eight FESAs on a spinning spacecraft are capable of measuring three dimensional electron distribution function with time resolution of 8 msec. FESA consists of two electrostatic analyzers that are composed of three nested hemispherical deflectors. Single FESA functions as four top-hat type electrostatic analyzers that can measure electrons with four different energies simultaneously. By measuring the characteristics of the test model FESA, we proved the validity of the design concept of FESA. Based on the measured characteristics, we designed FESA optimized for the SCOPE mission. This optimized analyzer has good enough performance to measure three dimensional electron distribution functions around the magnetic reconnection region in the Earth's magnetotail.

  17. High Time Resolution L-H Transition Studies on DIII-D

    NASA Astrophysics Data System (ADS)

    Wang, G.; Rhodes, T. L.; Doyle, E. J.; Zeng, L.; Peebles, W. A.; Burrell, K. H.; Groebner, R. J.; Evans, T. E.; Mahdavi, M. A.; McKee, G. R.; Moyer, R. A.; Rudakov, D. L.

    2003-10-01

    Understanding the L-H transition in tokamaks has been an important area of research for more than a decade. During the 2002 DIII-D experimental campaign the SOL density profile evolution through L-H transitions was measured with 25 μs time resolution using microwave reflectometry, and the correlation of the density gradient change with turbulence evolution was investigated. At the L-H transition it was observed that steady state SOL density profiles were not established until ˜1.7 ms after the D_α emission and density fluctuations reached steady state. This year, an experiment was performed to better characterize the L-H transition using recently improved diagnostics, e.g. a profile reflectometer system upgraded to measure density profile evolution both inside and outside the separatrix, so as to test and benchmark theoretical models, e.g. Guzdar et al., Phys. Rev. Lett. 89, 265004-1 (2002). Experimental results from the new system, and concurrent high time-resolution measurements of radial electric field, plasma rotation, and fluctuations will be reported and compared with theoretical models.

  18. High time resolution and size-segregated analysis of aerosol bound polycyclic aromatic hydrocarbons.

    PubMed

    Emmenegger, Christian; Kalberer, Markus; Samburova, Vera; Zenobi, Renato

    2005-06-01

    Polycyclic aromatic hydrocarbons (PAHs) are an ubiquitous class of compounds in the environment, mostly generated by anthropogenic processes. High time resolution measurements are necessary to gain further knowledge on the fate and diurnal pattern of these often carcinogenic and mutagenic compounds in the atmosphere. It is expected to find a strong correlation of the PAH levels with the strength and proximity to sources, as well as with meteorological parameters. To determine the fate of particle-bound PAHs, they were sampled in this study at an urban background site in Zurich, Switzerland, during summer 2002 and winter 2003. Particle-bound PAHs were collected with a rotating drum impactor and subsequently analyzed with two-step laser mass spectrometry. Using this combination of sampling and measurement, size-segregated (10-1.1, 1.1-0.3, and 0.3-0.1 microm) and high time resolution (20 min) data were obtained. The pronounced diurnal cycle (with day/night ratios of 0.1) was only altered during intensive atmospheric mixing periods (resulting in day/night ratios of up to 8) by cleaner air from upper atmospheric layers which was mixed into the boundary layer. During summer, signal intensities due to particle-bound PAHs were about a factor of 2-10 lower than during winter.

  19. A high-resolution time-depth view of dimethylsulphide cycling in the surface sea.

    PubMed

    Royer, S-J; Galí, M; Mahajan, A S; Ross, O N; Pérez, G L; Saltzman, E S; Simó, R

    2016-01-01

    Emission of the trace gas dimethylsulphide (DMS) from the ocean influences the chemical and optical properties of the atmosphere, and the olfactory landscape for foraging marine birds, turtles and mammals. DMS concentration has been seen to vary across seasons and latitudes with plankton taxonomy and activity, and following the seascape of ocean's physics. However, whether and how does it vary at the time scales of meteorology and day-night cycles is largely unknown. Here we used high-resolution measurements over time and depth within coherent water patches in the open sea to show that DMS concentration responded rapidly but resiliently to mesoscale meteorological perturbation. Further, it varied over diel cycles in conjunction with rhythmic photobiological indicators in phytoplankton. Combining data and modelling, we show that sunlight switches and tunes the balance between net biological production and abiotic losses. This is an outstanding example of how biological diel rhythms affect biogeochemical processes. PMID:27578300

  20. High-resolution imaging with a real-time synthetic aperture ultrasound system: a phantom study

    NASA Astrophysics Data System (ADS)

    Huang, Lianjie; Labyed, Yassin; Simonetti, Francesco; Williamson, Michael; Rosenberg, Robert; Heintz, Philip; Sandoval, Daniel

    2011-03-01

    It is difficult for ultrasound to image small targets such as breast microcalcifications. Synthetic aperture ultrasound imaging has recently developed as a promising tool to improve the capabilities of medical ultrasound. We use two different tissueequivalent phantoms to study the imaging capabilities of a real-time synthetic aperture ultrasound system for imaging small targets. The InnerVision ultrasound system DAS009 is an investigational system for real-time synthetic aperture ultrasound imaging. We use the system to image the two phantoms, and compare the images with those obtained from clinical scanners Acuson Sequoia 512 and Siemens S2000. Our results show that synthetic aperture ultrasound imaging produces images with higher resolution and less image artifacts than Acuson Sequoia 512 and Siemens S2000. In addition, we study the effects of sound speed on synthetic aperture ultrasound imaging and demonstrate that an accurate sound speed is very important for imaging small targets.

  1. A high-resolution time-depth view of dimethylsulphide cycling in the surface sea

    PubMed Central

    Royer, S.-J.; Galí, M.; Mahajan, A. S.; Ross, O. N.; Pérez, G. L.; Saltzman, E. S.; Simó, R.

    2016-01-01

    Emission of the trace gas dimethylsulphide (DMS) from the ocean influences the chemical and optical properties of the atmosphere, and the olfactory landscape for foraging marine birds, turtles and mammals. DMS concentration has been seen to vary across seasons and latitudes with plankton taxonomy and activity, and following the seascape of ocean’s physics. However, whether and how does it vary at the time scales of meteorology and day-night cycles is largely unknown. Here we used high-resolution measurements over time and depth within coherent water patches in the open sea to show that DMS concentration responded rapidly but resiliently to mesoscale meteorological perturbation. Further, it varied over diel cycles in conjunction with rhythmic photobiological indicators in phytoplankton. Combining data and modelling, we show that sunlight switches and tunes the balance between net biological production and abiotic losses. This is an outstanding example of how biological diel rhythms affect biogeochemical processes. PMID:27578300

  2. Dynamic imaging with high resolution time-of-flight pet camera - TOFPET I

    SciTech Connect

    Mullani, N.A.; Bristow, D.; Gaeta, J.; Gould, K.L.; Hartz, R.K.; Philipe, E.A.; Wong, W.H.; Yerian, K.

    1984-02-01

    One of the major design goals of the TOFPET I positron camera was to produce a high resolution whole body positron camera capable of dynamically imaging an organ such as the heart. TOFPET I is now nearing completion and preliminary images have been obtained to assess its dynamic and three dimensional imaging capabilities. Multiple gated images of the uptake of Rubidium in the dog heart and three dimensional surface displays of the distribution of the Rubidium-82 in the myocardium have been generated to demonstrate the three dimensional imaging properties. Fast dynamic images of the first pass of a bolus of radio-tracer through the heart have been collected with 4 second integration time and 50% gating (2 second equivalent integration time) with 18 mCi of Rb-82.

  3. KM3NeT Neutrino Telescope 1-ns Resolution Time To Digital Converters

    NASA Astrophysics Data System (ADS)

    Calvo, David; Real, Diego

    2016-04-01

    The KM3NeT collaboration aims the construction of a multi-km3 high-energy neutrino telescope in the Mediterranean sea consisting of thousands of glass spheres, each of them containing 31 photomultiplier of small photocathode area. The main digitization system is composed by 31 Time to Digital Converter channels with 1-ns resolution embedded in a Field Programmable Gate Array. An architecture with low resource occupancy has been chosen allowing the implementation of other instrumentation, communication and synchronization systems on the same device. The 4-oversampling technique with two high frequency clocks working in opposed phases has been used together with an asymmetric FIFO memory. In the present article the architecture and the first results obtained with the Time to Digital Converters are presented.

  4. A high-resolution time-depth view of dimethylsulphide cycling in the surface sea

    NASA Astrophysics Data System (ADS)

    Royer, S.-J.; Galí, M.; Mahajan, A. S.; Ross, O. N.; Pérez, G. L.; Saltzman, E. S.; Simó, R.

    2016-08-01

    Emission of the trace gas dimethylsulphide (DMS) from the ocean influences the chemical and optical properties of the atmosphere, and the olfactory landscape for foraging marine birds, turtles and mammals. DMS concentration has been seen to vary across seasons and latitudes with plankton taxonomy and activity, and following the seascape of ocean’s physics. However, whether and how does it vary at the time scales of meteorology and day-night cycles is largely unknown. Here we used high-resolution measurements over time and depth within coherent water patches in the open sea to show that DMS concentration responded rapidly but resiliently to mesoscale meteorological perturbation. Further, it varied over diel cycles in conjunction with rhythmic photobiological indicators in phytoplankton. Combining data and modelling, we show that sunlight switches and tunes the balance between net biological production and abiotic losses. This is an outstanding example of how biological diel rhythms affect biogeochemical processes.

  5. The RMS survey. 13CO observations of candidate massive YSOs in the southern Galactic plane

    NASA Astrophysics Data System (ADS)

    Urquhart, J. S.; Busfield, A. L.; Hoare, M. G.; Lumsden, S. L.; Oudmaijer, R. D.; Moore, T. J. T.; Gibb, A. G.; Purcell, C. R.; Burton, M. G.; Marechal, L. J. L.

    2007-11-01

    Context: The Red MSX Source (RMS) survey is an ongoing multi-wavelength observational programme designed to return a large, well-selected sample of massive young stellar objects (MYSOs). We have identified 2000 MYSOs candidates located within our Galaxy by comparing the colours of MSX and 2MASS point sources to those of known MYSOs. The aim of our follow-up observations is to identify other contaminating objects such as ultra compact (UC) HII regions, evolved stars and planetary nebulae (PNe) and distinguish between genuine MYSOs and nearby low-mass YSOs. Aims: A critical part of our follow-up programme is to conduct 13CO molecular line observations in order to determine kinematic distances to all of our MYSO candidates. These distances will be used in combination with far-IR and (sub)millimetre fluxes to determine bolometric luminosities which will allow us to identify and remove nearby low-mass YSOs. In addition these molecular line observations will help in identifying evolved stars which are weak CO emitters. Methods: We have used the 22 m Mopra telescope, the 15 m JCMT and the 20 m Onsala telescope to conduct molecular line observations towards 854 MYSOs candidates located in the 3rd and 4th quadrants. These observations have been made at the J = 1-0 (Mopra and Onsala) and J = 2-1 (JCMT) rotational transition frequency of 13CO molecules and have a spatial resolution of 20´´-40´´, a sensitivity of T{A}* ≃ 0.1 K and a velocity resolution of 0.2 km s-1. Results: We detect 13CO emission towards a total of 752 of the 854 RMS sources observed ( 88%). In total 2132 emission components are detected above 3σ level (typically T^*{A} ≥ 0.3 K). Multiple emission profiles are observed towards the majority of these sources - 461 sources ( 60%) - with an average of 4 molecular clouds detected along the line of sight. These multiple emission features make it difficult to assign a kinematic velocity to many of our sample. We have used archival CS (J = 2-1) and maser

  6. Coherence Conversion for Optimized Resolution in Optical Measurements - Example of Femtosecond Time Resolution Using the Transverse Coherence of 100-Picosecond X-Rays

    SciTech Connect

    Adams, Bernhard W.

    2015-01-01

    A way is proposed to obtain a femtosecond time resolution over a picosecond range in x-ray spectroscopic measurements where the light source and the detector are much slower than that. It is based on the invariance of the modulus of the Fourier transform to object translations. The method geometrically correlates time in the sample with x-ray amplitudes over a spatial coordinate, and then takes the optical Fourier transform through far-field diffraction. Thus, explicitly time-invariant intensities that encode the time evolution of the sample can be measured with a slow detector. This corresponds to a phase-space transformation that converts the transverse coherence to become effective in the longitudinal direction. Because synchrotron-radiation sources have highly anisotropic coherence properties with about $10^5$ longitudinal electromagnetic-field modes at 1 eV bandwidth, but only tens to hundreds transverse modes, coherence conversion can drastically improve the time resolution. Reconstruction of the femtosecond time evolution in the sample from the Fourier intensities is subject to a phase ambiguity that is well-known in crystallography. However, a way is presented to resolve it that is not available in that discipline. Finally, data from a demonstration experiment are presented. The same concept can be used to obtain attosecond time resolution with an x-ray free-electron laser.

  7. Real-time Precise Point Positioning with Ambiguity Resolution for Geosciences

    NASA Astrophysics Data System (ADS)

    Geng, J.; Meng, X.; Teferle, F. N.; Dodson, A. H.; Ge, M.; Shi, C.; Liu, J.

    2009-04-01

    Real-time provision of information on large scale crustal deformation during an earthquake can be crucial in assessing property damage and managing relief operations. Moreover, such a real-time monitoring system may even lead to the accurate prediction of earthquakes in future and help the subsequent studies on the mechanism involved. During the past two decades, Global Positioning System (GPS) measurements have been extensively applied to investigate such processes in the geosciences. Precise point positioning (PPP) using GPS based on single stations can achieve comparable accuracies to conventional relative positioning, when precise satellite orbits and clocks, and Earth rotation products are used. Thus, PPP does not need any reference stations to achieve high positioning accuracy, e.g. at the millimetre level in static and centimetre level in kinematic applications. This has both technical and economic advantages and may be the only feasible option in some specific applications such as Tsunami early warning systems. However, unlike relative positioning, PPP suffers from unresolved integer ambiguities, which prevented further accuracy improvements within short observation periods or in real-time. On account of the great potential of PPP, we developed a prototype real-time PPP system which also employs ambiguity resolution at a single station. This development is based on the PANDA (Positioning And Navigation Data Analyst) software, which was originally developed at Wuhan University in China, and has been significantly refined by the authors. To assess this system, about 30 stations from the EUREF Permanent Network Internet Protocol (EUREF-IP) pilot project are used to produce the real-time satellite clocks, with satellite orbits and Earth rotation parameters (ERP) fixed to the predicted part of the IGS (International GNSS Service) ultra-rapid products. This is followed by the estimation of the uncalibrated hardware delays (UHD), which are crucial in resolving the

  8. Single-pixel three-dimensional imaging with time-based depth resolution

    NASA Astrophysics Data System (ADS)

    Sun, Ming-Jie; Edgar, Matthew P.; Gibson, Graham M.; Sun, Baoqing; Radwell, Neal; Lamb, Robert; Padgett, Miles J.

    2016-07-01

    Time-of-flight three-dimensional imaging is an important tool for applications such as object recognition and remote sensing. Conventional time-of-flight three-dimensional imaging systems frequently use a raster scanned laser to measure the range of each pixel in the scene sequentially. Here we show a modified time-of-flight three-dimensional imaging system, which can use compressed sensing techniques to reduce acquisition times, whilst distributing the optical illumination over the full field of view. Our system is based on a single-pixel camera using short-pulsed structured illumination and a high-speed photodiode, and is capable of reconstructing 128 × 128-pixel resolution three-dimensional scenes to an accuracy of ~3 mm at a range of ~5 m. Furthermore, by using a compressive sampling strategy, we demonstrate continuous real-time three-dimensional video with a frame-rate up to 12 Hz. The simplicity of the system hardware could enable low-cost three-dimensional imaging devices for precision ranging at wavelengths beyond the visible spectrum.

  9. Evaluation of microvascular anastomosis using real-time ultrahigh resolution Fourier domain Doppler optical coherence tomography

    PubMed Central

    Huang, Yong; Tong, Dedi; Zhu, Shan; Wu, Lehao; Mao, Qi; Ibrahim, Zuhaib; Lee, WP Andrew; Brandacher, Gerald; Kang, Jin U.

    2014-01-01

    Background Evolution and improvements in microsurgical techniques and tools have paved the way for super-microsurgical anastomoses with vessel diameters often approaching below 0.8 mm in the clinical realm and even smaller (0.2–0.3 mm) in murine models. Several imaging and monitoring devices have been introduced for post-operative monitoring but intra-operative guidance, assessment and predictability have remained limited to binocular optical microscope and surgeon’s experience. We present a high-resolution real time 3D imaging modality for intra-operative evaluation of luminal narrowing, thrombus formation and flow alterations. Methods An imaging modality that provides immediate, in-depth high resolution 3D structure view and flow information of the anastomosed site called phase resolved Doppler optical coherence tomography (PRDOCT) was developed. 22 mouse femoral artery anastomoses and 17 mouse venous anastomoses were performed and evaluated with PRDOCT. Flow status, vessel inner lumen 3D structure, and early thrombus detection were analyzed based on PRDOCT imaging results. Initial PRDOCT based predictions were correlated with actual long term surgical outcomes. Eventually four cases of mouse orthotopic limb transplantation were carried out and PRDOCT predicted long term patency were confirmed by actual results. Results PRDOCT was able to provide high-resolution 3D visualization of the vessel flow status and vessel inner lumen. The assessments based on PRDOCT visualization shows a 92% sensitivity and 90% specificity for arterial anastomoses and 90% sensitivity and 86% specificity for venous anastomoses. Conclusions PRDOCT is an effective evaluation tool for microvascular anastomosis. It can predict the long term vessel patency with high sensitivity and specificity. PMID:25811583

  10. Optical and UV Sensing Sealed Tube Microchannel Plate Imaging Detectors with High Time Resolution

    NASA Astrophysics Data System (ADS)

    Siegmund, O.; Vallerga, J.; Tremsin, A.; Hull, J.; Elam, J.; Mane, A.

    2014-09-01

    Microchannel plate (MCP) based imaging, photon time tagging detector sealed tube schemes have a unique set of operational features that enable high time resolution astronomical and remote sensing applications to be addressed. New detectors using the cross strip (XS), cross delay line (XDL), or stripline anode readouts, a wide range of photocathode types, and advanced MCP technologies have been implemented to improve many performance characteristics. A variety of sealed tubes have been developed including 18mm XS readout devices with GaAs and SuperGenII photocathodes, 25mm XDL readout devices with SuperGenII and GaN photocathodes, and 20 x 20 cm sealed tubes with bialkali photocathodes and strip line readout. One key technology that has just become viable is the ability to make MCPs using atomic layer deposition (ALD) techniques. This employs nanofabrication of the active layers of an MCP on a microcapillary array. This technique opens new performance opportunities, including, very large MCP areas (>20cm), very low intrinsic background, lower radiation induced background, much longer overall lifetime and gain stability, and markedly lower outgassing which can improve the sealed tube lifetime and ease of fabrication. The XS readout has been implemented in formats of 22mm, 50mm and 100mm, and uses MCP charge signals detected on two orthogonal layers of conductive fingers to encode event X-Y positions. We have achieved spatial resolution XS detectors better than 25 microns FWHM, with good image linearity while at low gain (<10^6), substantially increasing local counting rate capabilities and the overall tube lifetime. XS tubes with updated electronics can encode event rates of >5 MHz with ~12% dead time and event timing accuracy of ~100ps. XDL sealed tubes in 25mm format demonstrate ~40 micron spatial resolution at up to ~2 MHz event rates, and have been developed with SupergenII visible regime photocathodes. The XDL tubes also achieve ~100 ps time resolution. Most

  11. Sub-100ps single photoelectron time resolution of a strip silicon photomultiplier for time-resolved optical spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Shenyuan; Liu, Rongdan; Liang, Kun; Yang, Ru; Han, Dejun

    2015-10-01

    SiPM with epitaxial quenching resistors developed at NDL (Novel Device Laboratory, Beijing) could alleviate the conflict between large dynamic range and high photon detection efficiency (PDE). It can be used as low light level detector in various applications with excellent single photoelectron time resolution (SPTR) and photon counting capacity. SPTR is mainly determined by the intrinsic structure parameters of the SiPM. However, it is also limited to measurement setup, electronics readout and the ultra-small signal of single photoelectron level. In this work, we designed and fabricated a 1 mm × 1 mm strip SiPM array for possible applications in time-resolved optical spectroscopy. The SiPM array consists of sixteen 50 μm × 1 mm strip SiPM elements. Each element contains five hundred 6.5 μm × 6.5 μm micro avalanche photodiode (APD) cells with 10μm pitch. The strip SiPM demonstrated SPTR of 68 ps (FWHM), peak PDE of 17% around 450 nm and high photon number resolving and photon counting capability.

  12. Cross strip microchannel plate imaging photon counters with high time resolution

    SciTech Connect

    Stonehill, Laura C; Shirey, Robert; Rabin, Michael W; Thompson, David C; Siegmund, Oswald H W; Vallerga, John V; Tremsin, Anton S

    2010-01-01

    We have implemented cross strip readout microchannel plate detectors in 18 mm active area format including open face (UV/particle) and sealed tube (optical) configurations. These have been tested with a field programmable gate array based parallel channel electronics for event encoding which can process high input event rates (> 5 MHz) with high spatial resolution. Using small pore MCPs (6 {micro}m) operated in a pair, we achieve gains of >5 x 10{sup 5} which is sufficient to provide spatial resolution of <35 {micro}m FHWM, with self triggered event timing accuracy of {approx}2 ns for sealed tube optical sensors. A peak quantum efficiency of {approx}19% at 500 nm has been achieved with SuperGenII photocathodes that have response over the 400 nm to 900 nm range. Local area counting rates of up to >200 events/mcp pore sec{sup -1} have been attained, along with image linearity and stability to better than 50 {micro}m.

  13. Aerosol chemical composition in cloud events by high resolution time-of-flight aerosol mass spectrometry.

    PubMed

    Hao, Liqing; Romakkaniemi, Sami; Kortelainen, Aki; Jaatinen, Antti; Portin, Harri; Miettinen, Pasi; Komppula, Mika; Leskinen, Ari; Virtanen, Annele; Smith, James N; Sueper, Donna; Worsnop, Douglas R; Lehtinen, Kari E J; Laaksonen, Ari

    2013-03-19

    This study presents results of direct observations of aerosol chemical composition in clouds. A high-resolution time-of-flight aerosol mass spectrometer was used to make measurements of cloud interstitial particles (INT) and mixed cloud interstitial and droplet residual particles (TOT). The differences between these two are the cloud droplet residuals (RES). Positive matrix factorization analysis of high-resolution mass spectral data sets and theoretical calculations were performed to yield distributions of chemical composition of the INT and RES particles. We observed that less oxidized hydrocarbon-like organic aerosols (HOA) were mainly distributed into the INT particles, whereas more oxidized low-volatile oxygenated OA (LVOOA) mainly in the RES particles. Nitrates existed as organic nitrate and in chemical form of NH(4)NO(3). Organic nitrates accounted for 45% of total nitrates in the INT particles, in clear contrast to 26% in the RES particles. Meanwhile, sulfates coexist in forms of acidic NH(4)HSO(4) and neutralized (NH(4))(2)SO(4). Acidic sulfate made up 64.8% of total sulfates in the INT particles, much higher than 10.7% in the RES particles. The results indicate a possible joint effect of activation ability of aerosol particles, cloud processing, and particle size effects on cloud formation.

  14. Blind, high-resolution, space-time separation of multipaths in an ionospheric propagation

    NASA Astrophysics Data System (ADS)

    Chenu-Tournier, M.; Larzabal, P.; Barbot, J. P.; Grouffaud, J.; Ferreol, A.

    2000-01-01

    The ionospheric radio electrical transmissions have multiple paths due to the inhomogeneity of the propagation medium, that is, the ionospheric layers. Tactical applications such as radiolocation and radiocommunications systems need blind, high-resolution identification of multipath channels. This work concerns the separation of the ionospheric paths and is based on recent work done on blind deconvolution which can estimate the impulse responses of a propagation channel. In this way, on the basis of a parametric model of the paths, we propose a blind, spatiotemporal identification of the propagation channel. The parameters that characterize the propagation model are the directions of arrivals (DOA) θ, time delays τ, and complex gains α (also called fading). We propose an algorithm that can both estimate the multipath parameters and test them on real life data. This new method needs fewer snapshots than other methods recently proposed, and thus can monitor more quickly varying channels. Moreover, compared to recent work we have relaxed the problem of making successive estimates of the impulse responses. The proposed method can also identify more paths than the number of sensors. An extension of the algorithm will be presented by including polarization diversity and thus increases the resolution. The proposed methods are illustrated on experimental data.

  15. Detection of the Anomalous Velocity with Subpicosecond Time Resolution in Semiconductor Nanostructures

    NASA Astrophysics Data System (ADS)

    Priyadarshi, Shekhar; Pierz, Klaus; Bieler, Mark

    2015-12-01

    We report on the time-resolved detection of the anomalous velocity, constituting charge carriers moving perpendicular to an electric driving field, in undoped GaAs quantum wells. For this we optically excite the quantum wells with circularly polarized femtosecond laser pulses, thereby creating a state which breaks time-inversion symmetry. We then employ a quasi-single-cycle terahertz pulse as an electric driving field to induce the anomalous velocity. The electromagnetic radiation emitted from the anomalous velocity is studied with a subpicosecond time resolution and reveals intriguing results. We are able to distinguish between intrinsic (linked to the Berry curvature) and extrinsic (linked to scattering) contributions to the anomalous velocity both originating from the valence band and observe local energy space dependence of the anomalous velocity. Our results thus constitute a significant step towards noninvasive probing of the anomalous velocity locally in the full energy-momentum space and enable the investigation of many popular physical effects such as the anomalous Hall effect and spin Hall effect on ultrafast time scales.

  16. An integrated CMOS time interval measurement system with subnanosecond resolution for the WA-98 calorimeter

    SciTech Connect

    Simpson, M.L.; Britton, C.L.; Wintenberg, A.L.; Young, G.R.

    1997-02-01

    The time interval measurement system of the WA-98 calorimeter is presented. This system consists of a constant fraction discriminator (CFD), a variable delay circuit, a time-to-amplitude converter (TAC), and a Wilkinson analog-to-digital converter (ADC) all realized in a 1.2-{micro}m N-well CMOS process. These circuits measured the time interval between a reference logic signal and a photomultiplier tube (PMT) signal that had amplitude variations of 100:1 and 10-ns rise and fall times. The system operated over the interval range from 2 ns to 200 ns with a resolution of {approximately}{+-}300 ps including all walk and jitter components. The variable delay circuit allowed the CFD output to be delayed /by up to 1 {micro}s with a jitter component of {approximately}0.04% of the delay setting. These circuits operated with a 5-V power supply. Although this application was in nuclear physics instrumentation, these circuits could also be useful in other scientific measurements, medical imaging, automatic test equipment, ranging systems, and industrial electronics.

  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. Time resolution of a 1-inch cylindrical CeBr{sub 3} crystal at {sup 60}Co energies

    SciTech Connect

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

    2013-06-10

    We have measured time resolutions of a cylindrical CeBr{sub 3} scintillator of 1-inch in height and 1-inch in diameter coupled to two different fast photomultiplier tubes, Hamamatsu R9779 and Photonis XP20D0, as a function of applied high voltages and different settings of a Constant Fraction Discriminator ORTEC 935. The time resolution was measured using a time-delayed coincidence set-up involving a fast reference detector. The best result of 119(2) ps at {sup 60}Co energies was obtained for the CeBr{sub 3} crystal coupled to the Hamamatsu PMT. This result is comparable to the resolution of 107 ps reported for a LaBr{sub 3}(Ce) crystal of the same size. For the coupling of the CeBr{sub 3} scintillator to the Photonis PMT we got the time resolution of 146(2) ps.

  19. Predicting Real-Time Soil Carbon Fluxes in Alaska at High Spatial Resolution

    NASA Astrophysics Data System (ADS)

    Pan, J.; Stieglitz, M.; Cheng, Y.; Pan, F.

    2013-12-01

    In this study we employ 3 full years (2009 - 2011) of high spatial resolution (7.5 km) hourly snapshots of snow depth and air temperatures throughout Alaska from Weather Underground (WU). We do so in order to demonstrate the practicalities of using real-time weather data to predict soil CO2 fluxes over large areas. As a preliminary step, hourly snow depth and air temperatures reported from WU were compared with observations from SNOTEL stations. WU reported hourly-daily air temperatures were consistent with observations. Likewise, snow depth in the interior of Alaska and on the North Slope matched observations well. In the Southeast coastal areas, WU reported snow depth were consistently low. We then used a simple empirical ground temperature scheme (Cheng et al., 2010) along with snow depth and air temperatures reported from WU to predict soil temperatures. Using these generated soil temperatures, as well as antecedent precipitation, a simple soil decomposition model was then calibrated with biophysical data from Barrow and Toolik Lake, Alaska. Post-calibration, model parameters were kept fixed and the model was run over the full hourly 2009 - 2011 record for the over 700 stations where we have measured soil carbon profiles. To test robustness, the model was calibrated independently at all location where we have good biophysical information and subsequently run over the remaining stations. These simulations demonstrate the degree to which real-time weather data can be trusted to provide an accurate high spatial resolution picture of daily, monthly, and seasonal soil C fluxes at high latitudes.

  20. Multi-colour High Time-resolution Simultaneous Photometric Studies of Blazars

    NASA Astrophysics Data System (ADS)

    Zhai, Meng

    2015-08-01

    highest time-resolution so far. The synchronized use of two or more telescopes could greatly improve the temporal resolution to help us monitor the outbursts of the blazars.

  1. Rms-flux relation and fast optical variability simulations of the nova-like system MV Lyr

    NASA Astrophysics Data System (ADS)

    Dobrotka, A.; Mineshige, S.; Ness, J.-U.

    2015-03-01

    The stochastic variability (flickering) of the nova-like system (subclass of cataclysmic variable) MV Lyr yields a complicated power density spectrum with four break frequencies. Scaringi et al. analysed high-cadence Kepler data of MV Lyr, taken almost continuously over 600 d, giving the unique opportunity to study multicomponent Power Density Spectra (PDS) over a wide frequency range. We modelled this variability with our statistical model based on disc angular momentum transport via discrete turbulent bodies with an exponential distribution of the dimension scale. Two different models were used, a full disc (developed from the white dwarf to the outer radius of ˜1010 cm) and a radially thin disc (a ring at a distance of ˜1010 cm from the white dwarf) that imitates an outer disc rim. We succeed in explaining the two lowest observed break frequencies assuming typical values for a disc radius of 0.5 and 0.9 times the primary Roche lobe and an α parameter of 0.1-0.4. The highest observed break frequency was also modelled, but with a rather small accretion disc with a radius of 0.3 times the primary Roche lobe and a high α value of 0.9 consistent with previous findings by Scaringi. Furthermore, the simulated light curves exhibit the typical linear rms-flux proportionality linear relation and the typical log-normal flux distribution. As the turbulent process is generating fluctuations in mass accretion that propagate through the disc, this confirms the general knowledge that the typical rms-flux relation is mainly generated by these fluctuations. In general, a higher rms is generated by a larger amount of superposed flares which is compatible with a higher mass accretion rate expressed by a larger flux.

  2. A low noise clock generator for high-resolution time-to-digital convertors

    NASA Astrophysics Data System (ADS)

    Prinzie, J.; Christiaensen, J.; Moreira, P.; Steyaert, M.; Leroux, P.

    2016-02-01

    A robust PLL clock generator has been designed for the harsh environment in high-energy physics applications. The PLL operates with a reference clock frequency of 40 MHz to 50 MHz and performs a multiplication by 64. An LC tank VCO with low internal phase noise can generate a frequency from 2.2 GHz up to 3.2 GHz with internal discrete bank switching. The PLL includes an automatic bank selection algorithm to correctly select the correct range of the oscillator. The PLL has been fabricated in a 65 nm CMOS technology and consumes less than 30 mW. The additive jitter of the PLL has been measured to be less than 400 fs RMS.

  3. Analytical Calculation of the Lower Bound on Timing Resolution for PET Scintillation Detectors Comprising High-Aspect-Ratio Crystal Elements

    PubMed Central

    Cates, Joshua W.; Vinke, Ruud; Levin, Craig S.

    2015-01-01

    Excellent timing resolution is required to enhance the signal-to-noise ratio (SNR) gain available from the incorporation of time-of-flight (ToF) information in image reconstruction for positron emission tomography (PET). As the detector’s timing resolution improves, so does SNR, reconstructed image quality, and accuracy. This directly impacts the challenging detection and quantification tasks in the clinic. The recognition of these benefits has spurred efforts within the molecular imaging community to determine to what extent the timing resolution of scintillation detectors can be improved and develop near-term solutions for advancing ToF-PET. Presented in this work, is a method for calculating the Cramér-Rao lower bound (CRLB) on timing resolution for scintillation detectors with long crystal elements, where the influence of the variation in optical path length of scintillation light on achievable timing resolution is non-negligible. The presented formalism incorporates an accurate, analytical probability density function (PDF) of optical transit time within the crystal to obtain a purely mathematical expression of the CRLB with high-aspect-ratio (HAR) scintillation detectors. This approach enables the statistical limit on timing resolution performance to be analytically expressed for clinically-relevant PET scintillation detectors without requiring Monte Carlo simulation-generated photon transport time distributions. The analytically calculated optical transport PDF was compared with detailed light transport simulations, and excellent agreement was found between the two. The coincidence timing resolution (CTR) between two 3×3×20 mm3 LYSO:Ce crystals coupled to analogue SiPMs was experimentally measured to be 162±1 ps FWHM, approaching the analytically calculated lower bound within 6.5%. PMID:26083559

  4. Real-time optoacoustic brain microscopy with hybrid optical and acoustic resolution

    NASA Astrophysics Data System (ADS)

    Estrada, Héctor; Turner, Jake; Kneipp, Moritz; Razansky, Daniel

    2014-04-01

    Conventional optoacoustic microscopy operates in two distinct modes of optical resolution, for visualization of superficial tissue layers, or acoustic resolution, intended for deep imaging in scattering tissues. Here we introduce a new microscope design with hybrid optical and acoustic resolution, which provides a smooth transition from optical resolution in superficial microscopic imaging to ultrasonic resolution when imaging at greater depths within intensely scattering tissue layers. Experimental validation of the new hybrid optoacoustic microscopy method was performed in phantoms and by means of transcranial mouse brain imaging in vivo.

  5. Development of high-rate MRPCs for high resolution time-of-flight systems

    NASA Astrophysics Data System (ADS)

    Wang, Jingbo; Wang, Yi; Gonzalez-Diaz, D.; Chen, Huangshan; Fan, Xingming; Li, Yuanjing; Cheng, Jianping; Kaspar, Marcus; Kotte, Roland; Laso Garcia, Alejandro; Naumann, Lothar; Stach, Daniel; Wendisch, Christian; Wüstenfeld, Jörn

    2013-06-01

    We show how the high charged-particle flux (1-20 kHz/cm2) expected over the 150 m2 large time-of-flight wall of the future Compressed Baryonic Matter experiment (CBM) at FAIR can be realistically handled with Multi-gap Resistive Plate Chambers (MRPCs). This crucial 100-fold increase of the chamber rate capability, as compared to that of standard MRPCs presently employed in experiments resorting to sub-100 ps timing, has been achieved thanks to the development of a new type of low-resistive doped glass. Following the encouraging results previously obtained with small counters, two types of modules (active area: ˜150 cm2) have been built at Tsinghua University with the new material. The measurements conveyed in this work, obtained with a quasi- minimum ionizing electron beam (γβ≥3), prove their suitability as the building blocks of the present hadron-identification concept of the CBM experiment. Namely, they provide a time resolution better than 80 ps and an efficiency above 90% at a particle flux well in excess of 20 kHz/cm2 (up to 35-60 kHz/cm2), being at the core of a modular concept that is easily scalable. Recent measurements of the electrical and mechanical properties of this new material, together with its long-term behavior, are shortly summarized.

  6. Improving the time resolution of surfzone bathymetry using in situ altimeters

    NASA Astrophysics Data System (ADS)

    Moulton, Melissa; Elgar, Steve; Raubenheimer, Britt

    2014-05-01

    Surfzone bathymetry often is resolved poorly in time because watercraft surveys cannot be performed when waves are large, and remote sensing techniques have limited vertical accuracy. However, accurate high-frequency bathymetric information at fixed locations can be obtained from altimeters that sample nearly continuously, even during storms. A method is developed to generate temporally and spatially dense maps of evolving surfzone bathymetry by updating infrequent spatially dense watercraft surveys with the bathymetric change measured by a spatially sparse array of nearly continuously sampling altimeters. The update method is applied to observations of the evolution of shore-perpendicular rip current channels (dredged in Duck, NC, 2012) and shore-parallel sandbars (observed in Duck, NC, 1994). The updated maps are compared with maps made by temporally interpolating the watercraft surveys, and with maps made by spatially interpolating the altimeter measurements at any given time. Updated maps of the surfzone rip channels and sandbars are more accurate than maps obtained by using either only watercraft surveys or only the altimeter measurements. Hourly altimeter-updated bathymetric estimates of five rip channels show rapid migration and infill events not resolved by watercraft surveys alone. For a 2-month observational record of sandbars, altimeter-updated maps every 6 h between nearly daily surveys improve the time resolution of rapid bar-migration events.

  7. Modeling a High Resolution Stream Chloride Time Series from the Biscuit Brook Catchment, Catskills, NY

    NASA Astrophysics Data System (ADS)

    Shaw, S. B.; Walter, M. T.; Harpold, A. A.

    2006-12-01

    Compelling work by Kirchner and colleagues (e.g., Kirchner et al., 2001, J. of Hydro., 254:81-100) suggests that lengthy, high resolution chloride time series can reveal the underlying travel time distribution of water in a catchment. However, few data sets of suitable length or sampling frequency have been available for assessment. Our analysis of a ten-year, weekly stream chloride time series data set for the steep, forested Biscuit Brook catchment in the Catskill Mountains of NY resulted in a 1/f spectral density plot. We used a lumped, two reservoir model with an upper reservoir representing quickflow and a lower reservoir representing base flow to reasonably replicate stream flow and stream chloride concentrations. A spectral analysis of the modeled daily chloride signal also resulted in a 1/f spectral density plot. This suggests that in some systems a 1/f signature can result from processes other than superposition of lateral chemical transport pathways, as has been previously hypothesized by other researchers. In this case, it appears that a long-term periodicity established by seasonal moisture deficits combines with shorter wavelength variations from rainfall inputs to create a 1/f spectral density for chloride concentration.

  8. Ultrasensitive Scanning Transmission X-ray Microscopy: Pushing the Limits of Time Resolution and Magnetic Sensitivity

    NASA Astrophysics Data System (ADS)

    Ohldag, Hendrik

    Understanding magnetic properties at ultrafast timescales is crucial for the development of new magnetic devices. Samples of interest are often thin film magnetic multilayers with thicknesses in the range of a few atomic layers. This fact alone presents a sensitivity challenge in STXM microscopy, which is more suited toward studying thicker samples. In addition the relevant time scale is of the order of 10 ps, which is well below the typical x-ray pulse length of 50 - 100 ps. The SSRL STXM is equipped with a single photon counting electronics that effectively allows using a double lock-in detection at 476MHz (the x-ray pulse frequency) and 1.28MHz (the synchrotron revelation frequency) to provide the required sensitivity. In the first year of operation the excellent spatial resolution, temporal stability and sensitivity of the detection electronics of this microscope has enabled researchers to acquire time resolved images of standing as well as traveling spin waves in a spin torque oscillator in real space as well as detect the real time spin accumulation in non magnetic Copper once a spin polarized current is injected into this material. The total magnetic moment is comparable to that of a single nanocube of magnetic Fe buried under a micron of non-magnetic material.

  9. Resolution of ray-finned fish phylogeny and timing of diversification.

    PubMed

    Near, Thomas J; Eytan, Ron I; Dornburg, Alex; Kuhn, Kristen L; Moore, Jon A; Davis, Matthew P; Wainwright, Peter C; Friedman, Matt; Smith, W Leo

    2012-08-21

    Ray-finned fishes make up half of all living vertebrate species. Nearly all ray-finned fishes are teleosts, which include most commercially important fish species, several model organisms for genomics and developmental biology, and the dominant component of marine and freshwater vertebrate faunas. Despite the economic and scientific importance of ray-finned fishes, the lack of a single comprehensive phylogeny with corresponding divergence-time estimates has limited our understanding of the evolution and diversification of this radiation. Our analyses, which use multiple nuclear gene sequences in conjunction with 36 fossil age constraints, result in a well-supported phylogeny of all major ray-finned fish lineages and molecular age estimates that are generally consistent with the fossil record. This phylogeny informs three long-standing problems: specifically identifying elopomorphs (eels and tarpons) as the sister lineage of all other teleosts, providing a unique hypothesis on the radiation of early euteleosts, and offering a promising strategy for resolution of the "bush at the top of the tree" that includes percomorphs and other spiny-finned teleosts. Contrasting our divergence time estimates with studies using a single nuclear gene or whole mitochondrial genomes, we find that the former underestimates ages of the oldest ray-finned fish divergences, but the latter dramatically overestimates ages for derived teleost lineages. Our time-calibrated phylogeny reveals that much of the diversification leading to extant groups of teleosts occurred between the late Mesozoic and early Cenozoic, identifying this period as the "Second Age of Fishes."

  10. Very-high-resolution time-lapse photography for plant and ecosystems research1

    PubMed Central

    Nichols, Mary H.; Steven, Janet C.; Sargent, Randy; Dille, Paul; Schapiro, Joshua

    2013-01-01

    • Premise of the study: Traditional photography is a compromise between image detail and area covered. We report a new method for creating time-lapse sequences of very-high-resolution photographs to produce zoomable images that facilitate observation across a range of spatial and temporal scales. • Methods and Results: A robotic camera mount and software were used to capture images of the growth and movement in Brassica rapa every 15 s in the laboratory. The resultant time-lapse sequence (http://timemachine.gigapan.org/wiki/Plant_Growth) captures growth detail such as circumnutation. A modified, solar-powered system was deployed at a remote field site in southern Arizona. Images were collected every 2 h over a 3-mo period to capture the response of vegetation to monsoon season rainfall (http://timemachine.gigapan.org/wiki/Arizona_Grasslands). • Conclusions: A technique for observing time sequences of both individual plant and ecosystem response at a range of spatial scales is available for use in the laboratory and in the field. PMID:25202588

  11. Monitoring environmental change in the Andes based on low resolution time series analysis

    NASA Astrophysics Data System (ADS)

    Tote, C.; Swinnen, E.; Beringhs, K.; Govers, G.

    2012-04-01

    Environmental change is an important issue in the Andes region and it is unknown to what extent the ongoing processes are a consequence of human impact and/or climate change. The objectives of this research are to study vegetation dynamics in the Andes region based on time series analysis of SPOT-Vegetation, NOAA-AVHRR and MODIS derived NDVI at low spatial but high temporal resolution, and to recognize to which extent this variability can be attributed to either climatic variability or human induced impacts through assimilation of satellite derived NDVI and rainfall data. Monthly rainfall estimates were available from the European Centre for Medium-Range Weather Forecasts (ECMWF) through MeteoConsult and the Monitoring Agricultural ResourceS (MARS) unit. Deviations from the 'average' situation were calculated for the NDVI time series using the Standardized Difference Vegetation Index (SDVI) and for the precipitation time series using the Standardized Precipitation Index (SPI). Correlation analysis between NDVI and SPI is performed in order to identify the temporal scale at which the environment is most sensitive to precipitation anomalies (best lag). Trends in SDVI and SPI are investigated using least square regression, taking into account the accumulated rainfall anomalies over the best lag. Hot spots of human induced environmental change are detected by subtraction of the precipitation induced signal on vegetation dynamics. The model can be used to predict possible effects of climate change in areas most sensible to trends in precipitation.

  12. Accurate estimation of the RMS emittance from single current amplifier data

    SciTech Connect

    Stockli, Martin P.; Welton, R.F.; Keller, R.; Letchford, A.P.; Thomae, R.W.; Thomason, J.W.G.

    2002-05-31

    This paper presents the SCUBEEx rms emittance analysis, a self-consistent, unbiased elliptical exclusion method, which combines traditional data-reduction methods with statistical methods to obtain accurate estimates for the rms emittance. Rather than considering individual data, the method tracks the average current density outside a well-selected, variable boundary to separate the measured beam halo from the background. The average outside current density is assumed to be part of a uniform background and not part of the particle beam. Therefore the average outside current is subtracted from the data before evaluating the rms emittance within the boundary. As the boundary area is increased, the average outside current and the inside rms emittance form plateaus when all data containing part of the particle beam are inside the boundary. These plateaus mark the smallest acceptable exclusion boundary and provide unbiased estimates for the average background and the rms emittance. Small, trendless variations within the plateaus allow for determining the uncertainties of the estimates caused by variations of the measured background outside the smallest acceptable exclusion boundary. The robustness of the method is established with complementary variations of the exclusion boundary. This paper presents a detailed comparison between traditional data reduction methods and SCUBEEx by analyzing two complementary sets of emittance data obtained with a Lawrence Berkeley National Laboratory and an ISIS H{sup -} ion source.

  13. Determining Rates of Permafrost Degradation Using a Time-Series of High-Resolution Imagery

    NASA Astrophysics Data System (ADS)

    Jorgenson, M. T.; Dissing, D.

    2008-12-01

    Quantifying the nature, extent, and rate of permafrost degradation requires high-resolution imagery because of the high variability in spatial and spectral characteristics of thermokarst landforms. Because rates of lateral degradation usually are <1 m/yr, a spatial resolution <2 m is required to adequately quantify degradation over 10-50 years. Due to the need for high-resolution imagery, however, it is practical to sample degradation only within small areas. We prefer to use high-resolution scans of film for historical airphotos, and to use newly acquired airphotos or high-resolution satellite imagery (e.g. Quickbird, Ikonos). Terrain-corrected satellite imagery is preferred as the base for georectifying and overlaying the historical photography. We prefer manual photointerpretation of permafrost boundaries over image processing because of the complexity of vegetation/surface water responses, and thus spectral characteristics, at the degrading margins. Change can be detected either by vectorizing boundaries of thermokarst landforms or point sampling across the entire time-series of images. While rates of surface permafrost degradation have yet to be assessed comprehensively in Alaska, our measurements of degradation at four sites across a climatic gradient using georectified airphotos provides some initial assessment. At Naknek in southwestern Alaska, the total area with recent thermokarst landforms developing in glacio-lacustrine deposits has increased from 35.5% in 1951 to 42% in 2000. On the Tanana Flats, central Alaska, recent thermokarst fens and bogs on abandoned floodplain deposits have increased from 39% in 1949 to 47% in 1995. At Cape Espenberg, Seward Peninsula, thermokarst lakes, basins, and thermokarst pits and troughs on eolian silt have increased from 73.9% in 1950 to 78.1% in 2005, with the high percentage of thermokarst terrain due to old, drained thaw-lake basins. At Fish Creek on the Beaufort Coastal Plain, where recent thermokarst polygonal

  14. High Resolution Spectroscopy And Timing Of The Isolated Neutron Star RBS 1774

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard (Technical Monitor); Drake, Jeremy

    2005-01-01

    The 2004 May 31 XMM-Newton observation was reprocessed using SASv6.0.0 and times of high background were filtered out. The net exposure time remaining was 23 ks. The source was clearly detected in MOS1, MOS2 and PN chips. We performed both timing and spectroscopic analysis on the data. We performed a spectral analysis by fitting data from the three EPIC detectors simultaneously, finding that the broadband spectrum can be represented by a single absorbed blackbody, with kT = 0.10 keV. The fitting revealed the presence of an absorption feature at 0:7 keV, but the data did have enough resolution to allow us to discriminate between an absorption line and an edge. We also tested magnetized models of Pavlov et a1 and Zavlin et al, but found that fits with these models were considerably worse than with a blackbody. For the timing analysis, we extracted the counts within a 3000 radius aperture in both PN and MOS 1 and MOS2 but with the aperture truncated by a chord where it approached the edge of the CCD window in each case: this maximized the counts while avoiding any edge effects. We analyzed PN, MOSl and MOS2 data both individually and combined using the Maximum Likelihood Periodogram technique of Zane et al. (2002) and Cropper et al. (2004). Periods from 10000 s to 30 ms were searched, ensuring that in each case the period grid was 2.5 times better sampled than the Nyquist frequency. The search revealed a significant period at 9.437s. Taken overall, we found the characteristics of RBS 1774 to be remarkably similar to those of another X-ray faint isolated neutron stars. These results were written up for the Astrophysical Journal, and the paper has recently been accepted for publication.

  15. Time-of-flight resolution of scintillating counters with Burle 85001 microchannel plate photomultipliers in comparison with Hamamatsu R2083

    NASA Astrophysics Data System (ADS)

    Baturin, V.; Burkert, V.; Kim, W.; Majewsky, S.; Park, K.; Popov, V.; Smith, E. S.; Son, D.; Stepanyan, S. S.; Zorn, C.

    2006-06-01

    Improvements in the time resolution of the CEBAF Large Acceptance Spectrometer (CLAS) below ≈50 ps will be required for experiments using the planned upgraded accelerator facility at Jefferson Lab. The improved time resolution will allow particle identification using time-of-flight techniques to be used effectively up to the proposed operating energy of 12 GeV. The challenge of achieving this time resolution over a relatively large area is compounded because the photomultipliers (PM) in the CLAS "time-zero" scintillating counters must operate in very high magnetic fields. Therefore, we have studied the resolution of "time-zero" prototypes with microchannel plate PMs 85001-501 from Burle. For reference and comparison, measurements were also made using the standard PMs R2083 from Hamamatsu using two timing methods. The cosmic ray method, which utilizes three identical scintillating counters (Bicron BC-408, 2×3×50 cm3) with PMs at the ends, yields σ=59.1±0.7 ps. The location method of particles from a radiative source with known coordinates has been used to compare timing resolutions of R2083 and 85001-501. This method yields σ=59.5±0.7 ps and it also provides an estimate of the number of primary photoelectrons. For the microchannel plate PM from Burle the method yields σ85001=130±4 ps due to lower number of primary photoelectrons.

  16. Fine resolution of early hominin time, Beds I and II, Olduvai Gorge, Tanzania.

    PubMed

    Stanistreet, Ian G

    2012-08-01

    Reconstructing paleoenvironments and landscapes within lake-centered, hominin-yielding basinal sequences requires a resolution of time-rock units finer than but complementary to that provided by the present tephrostratigraphy. Although indispensable in providing an absolute time frame at Olduvai, the average 15,000-20,000 year intervals between successive tuff units lack the time resolution to construct a sufficiently contemporary paleolandscape within sedimentary intervals away from the interleaved tuffs. Such control is essential to construct valid paleogeographies in which to contextualize contemporaneous paleoanthropological sites and the traces of hominin land use they contain. Within Beds I and II of the Olduvai Basin a Sequence Stratigraphic analysis has achieved a relative time framework in which time-rock units, "lake-parasequences," each generated by a major advance and withdrawal of the lake system, are recognizable for average periods of about 4000 years duration. Within each of these time slices at least two paleogeographic landscapes are identifiable, reducing the time constraints of an individual landscape reconstruction to a few thousand years. Within the sedimentary succession both highly incised and less incised unconformities are identifiable to provide sequence boundaries. Within each sequence the higher frequency lake-parasequences can be identified by (1) a disconformable base, (2) accretion of sediment during lake transgression and at maximum, (3) a disconformable top caused by lake withdrawal, and (4) a soil profile generated beneath that disconformable land surface. Individual lake-parasequences can be recognized in lake marginal and fan settings, and their imprint can also be seen in the lake setting where, for example, maximum flooding might be marked by a layer of dolomite. Lower Bed II parasequences represent time intervals of <5000 years, while parasequential periods between Tuffs IB and IC in Bed I are <4300 years. Analogous Holocene

  17. Time variations of narrow absorption lines in high resolution quasar spectra

    NASA Astrophysics Data System (ADS)

    Boissé, P.; Bergeron, J.; Prochaska, J. X.; Péroux, C.; York, D. G.

    2015-09-01

    Aims: We have searched for temporal variations of narrow absorption lines in high resolution quasar spectra. A sample of five distant sources were assembled, for which two spectra are available, either VLT/UVES or Keck/HIRES, which were taken several years apart. Methods: We first investigate under which conditions variations in absorption line profiles can be detected reliably from high resolution spectra and discuss the implications of changes in terms of small-scale structure within the intervening gas or intrinsic origin. The targets selected allow us to investigate the time behaviour of a broad variety of absorption line systems by sampling diverse environments: the vicinity of active nuclei, galaxy halos, molecular-rich galaxy disks associated with damped Lyα systems, as well as neutral gas within our own Galaxy. Results: Intervening absorption lines from Mg ii, Fe ii, or proxy species with lines of lower opacity tracing the same kind of (moderately ionised) gas appear in general to be remarkably stable (1σ upper limits as low as 10% for some components on scales in the range 10-100 au), even for systems at zabs ≈ ze. Marginal variations are observed for Mg ii lines towards PKS 1229-021 at zabs = 0.83032; however, we detect no systems that display any change as large as those reported in low resolution SDSS spectra. The lack of clear variations for low β Mg ii systems does not support the existence of a specific population of absorbers made of swept-up gas towards blazars. In neutral or diffuse molecular media, clear changes are seen for Galactic Na i lines towards PKS 1229-02 (decrease in N by a factor of four for one of the five components over 9.7 yr), corresponding to structure on a scale of about 35 au, in good agreement with known properties of the Galactic interstellar medium. Tentative variations are detected for H2J = 3 lines towards FBQS J2340-0053 at zabs = 2.05454 (≃35% change in column density, N, over 0.7 yr in the rest frame), suggesting

  18. Time series of high-resolution spectra of SN 2014J observed with the TIGRE telescope

    NASA Astrophysics Data System (ADS)

    Jack, D.; Mittag, M.; Schröder, K.-P.; Schmitt, J. H. M. M.; Hempelmann, A.; González-Pérez, J. N.; Trinidad, M. A.; Rauw, G.; Cabrera Sixto, J. M.

    2015-08-01

    We present a time series of high-resolution spectra of the Type Ia supernova 2014J, which exploded in the nearby galaxy M82. The spectra were obtained with the HEROS échelle spectrograph installed at the 1.2-m TIGRE telescope. We present a series of 33 spectra with a resolution of R ≈ 20 000, which covers the important bright phases in the evolution of SN 2014J during the period from 2014 January 24 to April 1. The spectral evolution of SN 2014J is derived empirically. The expansion velocities of the Si II P-Cygni features were measured and show the expected decreasing behaviour, beginning with a high velocity of 14 000 km s-1 on January 24. The Ca II infrared triplet feature shows a high-velocity component with expansion velocities of >20 000 km s-1 during the early evolution apart from the normal component showing similar velocities as Si II. Further broad P-Cygni profiles are exhibited by the principal lines of Ca II, Mg II and Fe II. The TIGRE SN 2014J spectra also resolve several very sharp Na I D doublet absorption components. Our analysis suggests interesting substructures in the interstellar medium of the host galaxy M82, as well as in our Milky Way, confirming other work on this SN. We were able to identify the interstellar absorption of M82 in the lines of Ca II H & K at 3933 and 3968 Å as well as K I at 7664 and 7698 Å. Furthermore, we confirm several diffuse interstellar bands, at wavelengths of 6196, 6283, 6376, 6379and 6613 Å and give their measured equivalent widths.

  19. Applying petrophysical models to radar travel time and electrical resistivity tomograms: Resolution-dependent limitations

    USGS Publications Warehouse

    Day-Lewis, F. D.; Singha, K.; Binley, A.M.

    2005-01-01

    Geophysical imaging has traditionally provided qualitative information about geologic structure; however, there is increasing interest in using petrophysical models to convert tomograms to quantitative estimates of hydrogeologic, mechanical, or geochemical parameters of interest (e.g., permeability, porosity, water content, and salinity). Unfortunately, petrophysical estimation based on tomograms is complicated by limited and variable image resolution, which depends on (1) measurement physics (e.g., electrical conduction or electromagnetic wave propagation), (2) parameterization and regularization, (3) measurement error, and (4) spatial variability. We present a framework to predict how core-scale relations between geophysical properties and hydrologic parameters are altered by the inversion, which produces smoothly varying pixel-scale estimates. We refer to this loss of information as "correlation loss." Our approach upscales the core-scale relation to the pixel scale using the model resolution matrix from the inversion, random field averaging, and spatial statistics of the geophysical property. Synthetic examples evaluate the utility of radar travel time tomography (RTT) and electrical-resistivity tomography (ERT) for estimating water content. This work provides (1) a framework to assess tomograms for geologic parameter estimation and (2) insights into the different patterns of correlation loss for ERT and RTT. Whereas ERT generally performs better near boreholes, RTT performs better in the interwell region. Application of petrophysical models to the tomograms in our examples would yield misleading estimates of water content. Although the examples presented illustrate the problem of correlation loss in the context of near-surface geophysical imaging, our results have clear implications for quantitative analysis of tomograms for diverse geoscience applications. Copyright 2005 by the American Geophysical Union.

  20. Stabilization technique for real-time high-resolution vascular ultrasound using frequency domain interferometry.

    PubMed

    Taki, Hirofumi; Taki, Kousuke; Yamakawa, Makoto; Shiina, Tsuyoshi; Kudo, Motoi; Sato, Toru

    2014-01-01

    We have proposed an ultrasound imaging method based on frequency domain interferometry (FDI) with an adaptive beamforming technique to depict real-time high-resolution images of human carotid artery. Our previous study has investigated the performance of the proposed imaging method under an ideal condition with a high signal-to-noise ratio (SNR). In the present study, we propose a technique that has the potential to improve accuracy in estimating echo intensity using the FDI imaging method. We investigated the performance of the proposed technique in a simulation study that two flat interfaces were located at depths of 15.0 and 15.2 mm and white noise was added. Because the -6 dB bandwidth of the signal used in this simulation study is 2.6 MHz, the conventional B-mode imaging method failed to depict the two interfaces. Both the conventional and proposed FDI imaging methods succeeded to depict the two interfaces when the SNR ranged from 15 to 30 dB. However, the average error of the estimated echo intensity at the interfaces using the conventional FDI imaging method ranged from 7.2 to 10.5 dB. In contrast, that using the FDI imaging method with the proposed technique ranged from 2.0 to 2.2 dB. The present study demonstrates the potential of the FDI imaging method in depicting robust and high-range-resolution ultrasound images of arterial wall, indicating the possibility to improve the diagnosis of atherosclerosis in early stages.

  1. EEG can Track the Time Course of Successful Reference Resolution in Small Visual Worlds

    PubMed Central

    Brodbeck, Christian; Gwilliams, Laura; Pylkkänen, Liina

    2015-01-01

    Previous research has shown that language comprehenders resolve reference quickly and incrementally, but not much is known about the neural processes and representations that are involved. Studies of visual short-term memory suggest that access to the representation of an item from a previously seen display is associated with a negative evoked potential at posterior electrodes contralateral to the spatial location of that item in the display. In this paper we demonstrate that resolving the reference of a noun phrase in a recently seen visual display is associated with an event-related potential that is analogous to this effect. Our design was adapted from the visual world paradigm: in each trial, participants saw a display containing three simple objects, followed by a question about the objects, such as Was the pink fish next to a boat?, presented word by word. Questions differed in whether the color adjective allowed the reader to identify the referent of the noun phrase or not (i.e., whether one or more objects of the named color were present). Consistent with our hypothesis, we observed that reference resolution by the adjective was associated with a negative evoked potential at posterior electrodes contralateral to spatial location of the referent, starting approximately 333 ms after the onset of the adjective. The fact that the laterality of the effect depended upon the location of the referent within the display suggests that reference resolution in visual domains involves, at some level, a modality-specific representation. In addition, the effect gives us an estimate of the time course of processing from perception of the written word to the point at which its meaning is brought into correspondence with the referential domain. PMID:26635689

  2. STS-57 MS2 Sherlock operates RMS THC on OV-105's aft flight deck

    NASA Technical Reports Server (NTRS)

    1993-01-01

    STS-57 Mission Specialist 2 (MS2) Nancy J. Sherlock operates the remote manipulator system (RMS) translation hand control (THC) while observing extravehicular activity (EVA) outside viewing window W10 on the aft flight deck of Endeavour, Orbiter Vehicle (OV) 105. Positioned at the onorbit station, Sherlock moved EVA astronauts in the payload bay (PLB). Payload Commander (PLC) G. David Low with his feet anchored to a special restraint device on the end of the RMS arm held MS3 Peter J.K. Wisoff during the RMS maneuvers. The activity represented an evaluation of techniques which might be used on planned future missions -- a 1993 servicing visit to the Hubble Space Telescope (HST) and later space station work -- which will require astronauts to frequently lift objects of similar sized bulk. Note: Just below Sherlock's left hand a 'GUMBY' toy watches the actvity.

  3. End-to-end RMS error testing on a constant bandwidth FM/FM system

    NASA Technical Reports Server (NTRS)

    Wallace, G. R.; Salter, W. E.

    1972-01-01

    End-to-end root-mean-square (rms) tests performed on a constant bandwidth FM/FM system with various settings of system parameters are reported. The testing technique employed is that of sampling, digitizing, delaying, and comparing the analog input against the sampled and digitized corresponding output. Total system error is determined by fully loading all channels with band-limited noise and conducting end-to-end rms error tests on one channel. Tests are also conducted with and without a transmission link and plots of rms errors versus receiver signal-to-noise (S/N) values are obtained. The combined effects of intermodulation, adjacent channel crosstalk, and residual system noise are determined as well as the single channel distortion of the system.

  4. Computation of rms spot radii by ray tracing. [size determination through telescope

    NASA Technical Reports Server (NTRS)

    Foreman, J. W., Jr.

    1974-01-01

    In a ray trace calculation of the rms radius of the spot formed in the image plane of an optical system by a point source object, a decision must be made as to how many rays will be traced to obtain the result. As the number of rays is increased, the rms spot radius is generally found to decrease, apparently approaching a definite lower limit as the number of rays becomes very large. This paper examines the question of how many rays must be traced and what their geometrical distribution within the aperture should be to approach the limiting value of the rms spot radius for an infinite number of rays within an accuracy of approximately 1%.

  5. Exploiting crowdsourced observations: High-resolution mapping of real-time urban air quality throughout Europe

    NASA Astrophysics Data System (ADS)

    Schneider, Philipp; Castell, Nuria; Vallejo, Islen; van den Bossche, Joris; Lahoz, William; Bartonova, Alena

    2016-04-01

    With the technology of air quality sensors improving rapidly in recent years and with an increasing number of initiatives for collecting air quality information being established worldwide, there is a rapidly increasing amount of information on air quality. Such datasets can provide unprecedented spatial detail and thus exhibit a significant potential for allowing to create observation-based high-resolution maps of air quality in the urban environment. However, most datasets of observations made within a citizen science or crowdsourcing framework tend to have highly variable characteristics in terms of quantity, accuracy, measured parameters, and representativeness, and many more. It is therefore currently unknown how to best exploit this information for mapping purposes. In order to address this challenge we present a novel approach for combining crowdsourced observations of urban air quality with model information, allowing us to produce near-real-time, high-resolution maps of air quality in the urban environment. The approach is based on data fusion techniques, which allow for combining observations with model data in a mathematically objective way and therefore provide a means of adding value to both the observations and the model. The observations are improved by filling spatio-temporal gaps in the data and the model is improved by constraining it with observations. The model further provides detailed spatial patterns in areas where no observations are available. As such, data fusion of observations from high-density low-cost sensor networks together with air quality models can contribute to significantly improving urban-scale air quality mapping. The system has been implemented to run in an automated fashion in near real-time (once every hour) for several cities in Europe. Evaluation of the methodology is being carried out using the leave-one-out cross validation technique and simulated datasets. We present case studies demonstrating the methodology for

  6. A modified infrared spectrometer with high time resolution and its application for investigating fast conformational changes of the GTPase Ras.

    PubMed

    Lin, Jie; Gerwert, Klaus; Kötting, Carsten

    2014-01-01

    Time-resolved infrared spectroscopy is a valuable tool for the investigation of proteins and protein interactions. The investigation of many biological processes is possible by means of caged compounds, which set free biologically active substances upon light activation. Some caged compounds could provide sub-nanosecond time resolution, e.g., para-hydroxyphenacyl-guanosine 5'-triphosphate (GTP) forms GTP in picoseconds. However, the time resolution in single shot experiments with rapid-scan Fourier transform infrared (FT-IR) spectrometers is limited to about 10 ms. Here we use an infrared diode laser instead of the conventional globar and achieve a time resolution of 100 ns. This allows for the time-resolved measurement of the fast Ras(off) to Ras(on) conformational change at room temperature. We quantified the activation parameters for this reaction and found that the free energy of activation for this reaction is mainly enthalpic. Investigation of the same reaction in the presence of the Ras binding domain of the effector Raf (RafRBD) reveals a four orders of magnitude faster reaction, indicating that Ras·RafRBD complex formation directly induces the conformational change. Recent developments of broadly tunable quantum cascade lasers will further improve time resolution and usability of the setup. The reported 100 ns time resolution is the best achieved for a non-repetitive experiment so far.

  7. Incidental nutrient transfers: Assessing critical times in agricultural catchments using high-resolution data.

    PubMed

    Shore, Mairead; Jordan, Phil; Melland, Alice R; Mellander, Per-Erik; McDonald, Noeleen; Shortle, Ger

    2016-05-15

    Managing incidental losses associated with liquid slurry applications during closed periods has significant cost and policy implications and the environmental data required to review such a measure are difficult to capture due to storm dependencies. Over four years (2010-2014) in five intensive agricultural catchments, this study used high-resolution total and total reactive phosphorus (TP and TRP), total oxidised nitrogen (TON) and suspended sediment (SS) concentrations with river discharge data to investigate the magnitude and timing of nutrient losses. A large dataset of storm events (defined as 90th percentile discharges), and associated flow-weighted mean (FWM) nutrient concentrations and TP/SS ratios, was used to indicate when losses were indicative of residual or incidental nutrient transfers. The beginning of the slurry closed period was reflective of incidental and residual transfers with high storm FWM P (TP and TRP) concentrations, with some catchments also showing elevated storm TP:SS ratios. This pattern diminished at the end of the closed period in all catchments. Total oxidised N behaved similarly to P during storms in the poorly drained catchments and revealed a long lag time in other catchments. Low storm FWM P concentrations and TP:SS ratios during the weeks following the closed period suggests that nutrients either weren't applied during this time (best times chosen) or that they were applied to less risky areas (best places chosen). For other periods such as late autumn and during wet summers, where storm FWM P concentrations and TP:SS ratios were high, it is recommended that an augmentation of farmer knowledge of soil drainage characteristics with local and detailed current and forecast soil moisture conditions will help to strengthen existing regulatory frameworks to avoid storm driven incidental nutrient transfers. PMID:26933967

  8. Visual perception in space and time--mapping the visual field of temporal resolution.

    PubMed

    Poggel, Dorothe A; Strasburger, Hans

    2004-01-01

    To characterize temporal aspects of information processing in the human visual field, we studied the topographical distribution of temporal and non-temporal performance parameters in 95 normally sighted subjects. Visual field maps of double-pulse resolution thresholds (DPR) (the minimum detectable temporal gap between two light stimuli) and simple visual reaction times (RT) (measuring the speed of reaction to a light stimulus) were compared to maps of luminance thresholds determined by standard perimetry. Thus, for the first time, the topography of a visual variable without temporal constraints (perimetry) could be compared to visual variables in the temporal domain, with (RT) and without (DPR) motor reaction. The goal of the study was to obtain and to describe the pattern of co-variation of performance indicators. In all three measures, performance was best in the central visual field and dropped significantly towards the periphery. Although the correlation between DPR and RT was significant, shared variance was low, and we observed large topographical differences between these two temporal-performance variables. In contrast, DPR and perimetric thresholds correlated more substantially, and visual field maps were similar. The Gestalt of DPR maps shares characteristics of basic visual processing (e.g., light sensitivity), but it also reflects top-down influences, i.e., from spatial attention. Although the correlation between DPR and RT suggests common characteristics between these two temporal variables, the topographic distributions reveal significant differences, indicating separate underlying processing mechanisms. PMID:15283484

  9. A time accurate finite volume high resolution scheme for three dimensional Navier-Stokes equations

    NASA Technical Reports Server (NTRS)

    Liou, Meng-Sing; Hsu, Andrew T.

    1989-01-01

    A time accurate, three-dimensional, finite volume, high resolution scheme for solving the compressible full Navier-Stokes equations is presented. The present derivation is based on the upwind split formulas, specifically with the application of Roe's (1981) flux difference splitting. A high-order accurate (up to the third order) upwind interpolation formula for the inviscid terms is derived to account for nonuniform meshes. For the viscous terms, discretizations consistent with the finite volume concept are described. A variant of second-order time accurate method is proposed that utilizes identical procedures in both the predictor and corrector steps. Avoiding the definition of midpoint gives a consistent and easy procedure, in the framework of finite volume discretization, for treating viscous transport terms in the curvilinear coordinates. For the boundary cells, a new treatment is introduced that not only avoids the use of 'ghost cells' and the associated problems, but also satisfies the tangency conditions exactly and allows easy definition of viscous transport terms at the first interface next to the boundary cells. Numerical tests of steady and unsteady high speed flows show that the present scheme gives accurate solutions.

  10. Microsecond Time Resolution Optical Photometry using a H.E.S.S. Cherenkov Telescope

    SciTech Connect

    Deil, Christoph; Domainko, Wilfried; Hermann, German

    2008-02-22

    We have constructed an optical photometer with microsecond time resolution, which is currently being operated on one of the H.E.S.S. telescopes. H.E.S.S. is an array of four Cherenkov telescopes, each with a 107 m{sup 2} mirror, located in the Khomas highland in Namibia. In its normal mode of operation H.E.S.S. observes Cherenkov light from air showers generated by very high energy gamma-rays in the upper atmosphere. Our detector consists of seven photomultipliers, one in the center to record the lightcurve from the target and six concentric photomultipliers as a veto system to reject disturbing signals e.g. from meteorites or lightning at the horizon. The data acquisition system has been designed to continuously record the signals with zero deadtime. The Crab pulsar has been observed to verify the performance of the instrument and the GPS timing system. Compact galactic targets were observed to search for flares on timescales of a few microseconds to {approx}100 ms. The design and sensitivity of the instrument as well as the data analysis method are presented.

  11. Wideband fluorescence-based thermometry by neural network recognition: Photothermal application with 10 ns time resolution

    NASA Astrophysics Data System (ADS)

    Liu, Liwang; Zhong, Kuo; Munro, Troy; Alvarado, Salvador; Côte, Renaud; Creten, Sebastiaan; Fron, Eduard; Ban, Heng; Van der Auweraer, Mark; Roozen, N. B.; Matsuda, Osamu; Glorieux, Christ

    2015-11-01

    Neural network recognition of features of the fluorescence spectrum of a thermosensitive probe is exploited in order to achieve fluorescence-based thermometry with an accuracy of 200 mK with 100 MHz bandwidth, and with high robustness against fluctuations of the probe laser intensity used. The concept is implemented on a rhodamine B dyed mixture of copper chloride and glycerol, and the temperature dependent fluorescence is investigated in the temperature range between 234 K and 311 K. The spatial dependence of the calibrated amplitude and phase of photothermally induced temperature oscillations along the axis of the excitation laser are determined at different modulation frequencies. The spatial and frequency dependence of the extracted temperature signals is well fitted by a 1D multi-layer thermal diffusion model. In a time domain implementation of the approach, the gradual temperature rise due to the accumulation of the DC component of the heat flux supplied by repetitive laser pulses as well the immediate transient temperature evolution after each single pulse is extracted from acquired temporal sequences of fluorescence spectra induced by a CW green laser. A stroboscopic implementation of fluorescence thermometry, using a pulsed fluorescence evoking probe laser, is shown to achieve remote detection of temperature changes with a time resolution of 10 ns.

  12. Following Molecular Transitions with Single Residue Spatial and Millisecond Time Resolution

    SciTech Connect

    Shcherbakova,I.; Mitra, S.; Beer, R.; Brenowitz, M.

    2008-01-01

    'Footprinting' describes assays in which ligand binding or structure formation protects polymers such as nucleic acids and proteins from either cleavage or modification; footprinting allows the accessibility of individual residues to be mapped in solution. Equilibrium and time-dependent footprinting links site-specific structural information with thermodynamic and kinetic transitions, respectively. The hydroxyl radical ({center_dot}OH) is a uniquely insightful footprinting probe by virtue of it being among the most reactive chemical oxidants; it reports the solvent accessibility of reactive sites on macromolecules with as fine as a single residue resolution. A novel method of millisecond time-resolved {center_dot}OH footprinting is presented based on the Fenton reaction, Fe(II) + H2O2 {yields} Fe(III) + {center_dot}OH + OH-. It is implemented using a standard three-syringe quench-flow mixer. The utility of this method is demonstrated by its application to the studies on RNA folding. Its applicability to a broad range of biological questions involving the function of DNA, RNA, and proteins is discussed.

  13. Development of High-resolution Real-Time Strong Motion Observation Network in CEORKA

    NASA Astrophysics Data System (ADS)

    Akazawa, T.; Araki, M.; Sawada, S.; Hayashi, Y.; Horike, M.

    2011-12-01

    The Committee of Earthquake Observation and Research in the Kansai Area (CEORKA), distributing 20 stations throughout the Kansai district in Japan, has obtained many velocity records, not only during major earthquakes (e.g. 1995 Kobe Earthquake and 2011 Tohoku Earthquake) but also during moderate ones (M>2) occurred in and near the district. The committee continues to use the old data loggers, which were installed in 1994 and 1997. It takes more than one hour after the shaking to collect the time history records, because dial-up telecommunication lines are used. In addition, the data logger starts saving the observed data when the ground shaking exceeds a preset level. This "trigger" system do not often store the valuable data properly. We develop a new low-cost data logger (KS-002D), which can send the observed data in real-time through Internet and save it in SD card continuously, for the network of CEORKA. The logger has eight input channels to obtain both high and low gain signals output from the existing strong motion seismograph (VSE-11 & 12). The logger also gets the high accuracy clock signals from GPS system. The observed data show that the new date logger can obtain broadband and high-resolution data from strong motion to microtremor. The developed data loggers are installed to the all stations of CEORKA, in addition to old loggers which are working as back-up systems.

  14. Superconducting single-photon counting system for optical experiments requiring time-resolution in the picosecond range

    NASA Astrophysics Data System (ADS)

    Toussaint, Julia; Grüner, Roman; Schubert, Marco; May, Torsten; Meyer, Hans-Georg; Dietzek, Benjamin; Popp, Jürgen; Hofherr, Matthias; Arndt, Matthias; Henrich, Dagmar; Il'in, Konstantin; Siegel, Michael

    2012-12-01

    We have developed a cryogenic measurement system for single-photon counting, which can be used in optical experiments requiring high time resolution in the picosecond range. The system utilizes niobium nitride superconducting nanowire single-photon detectors which are integrated in a time-correlated single-photon counting (TCSPC) setup. In this work, we describe details of the mechanical design, the electrical setup, and the cryogenic optical components. The performance of the complete system in TCSPC mode is tentatively benchmarked using 140 fs long laser pulses at a repetition frequency of 75 MHz. Due to the high temporal stability of these pulses, the measured time resolution of 35 ps (FWHM) is limited by the timing jitter of the measurement system. The result was cross-checked in a Coherent Anti-stokes Raman Scattering (CARS) setup, where scattered pulses from a β-barium borate crystal have been detected with the same time resolution.

  15. A photoelectron-photoion coincidence imaging apparatus for femtosecond time-resolved molecular dynamics with electron time-of-flight resolution of {sigma}=18 ps and energy resolution {delta}E/E=3.5%

    SciTech Connect

    Vredenborg, Arno; Roeterdink, Wim G.; Janssen, Maurice H. M.

    2008-06-15

    We report on the construction and performance of a novel photoelectron-photoion coincidence machine in our laboratory in Amsterdam to measure the full three-dimensional momentum distribution of correlated electrons and ions in femtosecond time-resolved molecular beam experiments. We implemented sets of open electron and ion lenses to time stretch and velocity map the charged particles. Time switched voltages are operated on the particle lenses to enable optimal electric field strengths for velocity map focusing conditions of electrons and ions separately. The position and time sensitive detectors employ microchannel plates (MCPs) in front of delay line detectors. A special effort was made to obtain the time-of-flight (TOF) of the electrons at high temporal resolution using small pore (5 {mu}m) MCPs and implementing fast timing electronics. We measured the TOF distribution of the electrons under our typical coincidence field strengths with a temporal resolution down to {sigma}=18 ps. We observed that our electron coincidence detector has a timing resolution better than {sigma}=16 ps, which is mainly determined by the residual transit time spread of the MCPs. The typical electron energy resolution appears to be nearly laser bandwidth limited with a relative resolution of {delta}E{sub FWHM}/E=3.5% for electrons with kinetic energy near 2 eV. The mass resolution of the ion detector for ions measured in coincidence with electrons is about {delta}m{sub FWHM}/m=1/4150. The velocity map focusing of our extended source volume of particles, due to the overlap of the molecular beam with the laser beams, results in a parent ion spot on our detector focused down to {sigma}=115 {mu}m.

  16. STS-31 Hubble Space Telescope (HST) is grappled by OV-103 RMS

    NASA Technical Reports Server (NTRS)

    1990-01-01

    During STS-31, the Hubble Space Telescope (HST), grappled by the remote manipulator system (RMS) end effector, is held against the blackness of space. The two solar array (SA) wings (large gold panels) are fully extended with bistem cassette and secondary deployment mechanism (SDM) handle clearly visible. The two deployed high gain antennae (HGA) masts are parallel to the SA panels. RMS end effector is positioned on the starboard fixture during the predeployment checkout operations above Discovery's, Orbiter Vehicle (OV) 103's, payload bay (PLB).

  17. OV-104's RMS releases Gamma Ray Observatory (GRO) during STS-37 deployment

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Atlantis', Orbiter Vehicle (OV) 104's, remote manipulator system (RMS) releases Gamma Ray Observatory (GRO) during STS-37 deployment. Visible on the GRO as it drifts away from the RMS end effector are the four complement instruments: the Energetic Gamma Ray Experiment (bottom); Imaging Compton Telescope (COMPTEL) (center); Oriented Scintillation Spectrometer Experiment (OSSE) (top); and Burst and Transient Source Experiment (BATSE) (at four corners). GRO's solar array (SA) panels are extended and are in orbit configuration. View was taken through aft flight deck window which reflects some of the crew compartment interior.

  18. OV-104's RMS releases Gamma Ray Observatory (GRO) during STS-37 deployment

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Atlantis', Orbiter Vehicle (OV) 104's, remote manipulator system (RMS) releases Gamma Ray Observatory (GRO) during STS-37 deployment. Visible on the GRO as it drifts away from the RMS end effector are the four complement instruments: the Energetic Gamma Ray Experiment (bottom); Imaging Compton Telescope (COMPTEL) (center); Oriented Scintillation Spectrometer Experiment (OSSE) (top); and Burst and Transient Source Experiment (BATSE) (at four corners). GRO's solar array (SA) panels are extended and are in orbit configuration. View was taken through aft flight deck overhead window W8 which reflects some of the crew compartment interior. A small section of the Earth's limb is visible in the corner of the window.

  19. CRISTA-SPAS payload on the STS-66 shuttle Atlantis RMS arm

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Masses of clouds over the Atlantic Ocean serve as the backdrop for this close-up scene of the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA), attached to the Shuttle Pallet System (SPAS). CRISTA-SPAS was in the grasp of the Space Shuttle Atlantis Remote Manipulator System (RMS) arm. The crew deployed the Crista-SPAS on November 4, 1994 and the tandem remained in free-flight until November 12, 1994 when it was retrieved by the Canadian-built RMS, controlled by payload commander Ellen Ochoa.

  20. STS-57 remote manipulator system (RMS) grapples EURECA over OV-105's PLB

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The European Retrievable Carrier (EURECA), with solar array (SA) panels folded up flat against the spacecraft, is grappled by the remote manipulator system (RMS) end effector and held over the payload bay (PLB) of Endeavour, Orbiter Vehicle (OV) 105. The RMS will ease EURECA into its stowage position in OV-105's aft PLB for return to Earth. Partially visible in the foreground are the SPACEHAB-01 module and the Superfluid Helium Onorbit Transfer (SHOOT) liquid helium dewar assembly. The Earth's limb creates the backdrop for the scene.

  1. A simple explanation of the linear rms-mean flux relation in accreting objects

    NASA Astrophysics Data System (ADS)

    Koen, C.

    2016-09-01

    Aims: We provide an alternative to existing theories for the origin of linear rms-mean flux relations observed in a variety of accreting systems, from AGN to white dwarfs. Methods: Standard statistical theory and simulations are used to explore the possibility that the relations are due to simple scaling effects. Results: The proposed theory can reproduce the unit slope of the rms-mean flux relation observed in the most extensive study published to date. The close similarity of the fractional variability in different objects deserves further study.

  2. Fast-time Simulation of an Automated Conflict Detection and Resolution Concept

    NASA Technical Reports Server (NTRS)

    Windhorst, Robert; Erzberger, Heinz

    2006-01-01

    This paper investigates the effect on the National Airspace System of reducing air traffc controller workload by automating conflict detection and resolution. The Airspace Concept Evaluation System is used to perform simulations of the Cleveland Center with conventional and with automated conflict detection and resolution concepts. Results show that the automated conflict detection and resolution concept significantly decreases growth of delay as traffic demand is increased in en-route airspace.

  3. Polychlorinated biphenyls (PCBs) analysis using a miniaturized high-resolution time-of-flight mass spectrometer "MULTUM-S II".

    PubMed

    Shimma, Shuichi; Miki, Shinichi; Toyoda, Michisato

    2012-05-01

    In this study, we conducted polychlorinated biphenyls (PCBs) analysis using fast gas chromatography (GC)/high-resolution mass spectrometry (HRMS). Mass spectrometry (MS) was performed with a miniature multi-turn time-of-flight (TOF) analyzer called "MULTUM-S II". MULTUM-S II is truly a portable high resolution mass spectrometer. The mass spectrometer's high resolution capability is due to its theoretical infinite flight path utilizing perfect space and time focusing within a closed flight orbit. Mass resolution above 10 000 was easily achievable employing this portable system. This mass resolution is comparable to magnetic sector mass spectrometers, which have traditionally performed PCB analyses in the past. At a resolution of 10 000, a limit-of-detection of 1 ppb was determined using a heptachlorinated biphenyl standard sample. Using this fast GC/HRMS, 66 PCB congeners were analyzed within 5 min. In addition experiments aimed at confirming interference of PCB signal peaks and matrix peaks in diluted dielectric coolant fluids were performed. We found that the PCB signal peaks were detected without matrix interference via high mass resolution.

  4. SNSMIL, a real-time single molecule identification and localization algorithm for super-resolution fluorescence microscopy

    PubMed Central

    Tang, Yunqing; Dai, Luru; Zhang, Xiaoming; Li, Junbai; Hendriks, Johnny; Fan, Xiaoming; Gruteser, Nadine; Meisenberg, Annika; Baumann, Arnd; Katranidis, Alexandros; Gensch, Thomas

    2015-01-01

    Single molecule localization based super-resolution fluorescence microscopy offers significantly higher spatial resolution than predicted by Abbe’s resolution limit for far field optical microscopy. Such super-resolution images are reconstructed from wide-field or total internal reflection single molecule fluorescence recordings. Discrimination between emission of single fluorescent molecules and background noise fluctuations remains a great challenge in current data analysis. Here we present a real-time, and robust single molecule identification and localization algorithm, SNSMIL (Shot Noise based Single Molecule Identification and Localization). This algorithm is based on the intrinsic nature of noise, i.e., its Poisson or shot noise characteristics and a new identification criterion, QSNSMIL, is defined. SNSMIL improves the identification accuracy of single fluorescent molecules in experimental or simulated datasets with high and inhomogeneous background. The implementation of SNSMIL relies on a graphics processing unit (GPU), making real-time analysis feasible as shown for real experimental and simulated datasets. PMID:26098742

  5. 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

  6. Microwells support high-resolution time-lapse imaging and development of preimplanted mouse embryos

    PubMed Central

    Chung, Yu-Hsiang; Hsiao, Yi-Hsing; Kao, Wei-Lun; Hsu, Chia-Hsien; Chen, Chihchen

    2015-01-01

    A vital aspect affecting the success rate of in vitro fertilization is the culture environment of the embryo. However, what is not yet comprehensively understood is the affect the biochemical, physical, and genetic requirements have over the dynamic development of human or mouse preimplantation embryos. The conventional microdrop technique often cultures embryos in groups, which limits the investigation of the microenvironment of embryos. We report an open microwell platform, which enables micropipette manipulation and culture of embryos in defined sub-microliter volumes without valves. The fluidic environment of each microwell is secluded from others by layering oil on top, allowing for non-invasive, high-resolution time-lapse microscopy, and data collection from each individual embryo without confounding factors. We have successfully cultured mouse embryos from the two-cell stage to completely hatched blastocysts inside microwells with an 89% success rate (n = 64), which is comparable to the success rate of the contemporary practice. Development timings of mouse embryos that developed into blastocysts are statistically different to those of embryos that failed to form blastocysts (p–value < 10−10, two-tailed Student's t-test) and are robust indicators of the competence of the embryo to form a blastocyst in vitro with 94% sensitivity and 100% specificity. Embryos at the cleavage- or blastocyst-stage following the normal development timings were selected and transferred to the uteri of surrogate female mice. Fifteen of twenty-two (68%) blastocysts and four of ten (40%) embryos successfully developed into normal baby mice following embryo transfer. This microwell platform, which supports the development of preimplanted embryos and is low-cost, easy to fabricate and operate, we believe, opens opportunities for a wide range of applications in reproductive medicine and cell biology. PMID:26015830

  7. Intra-hole fluid convection: High-resolution temperature time monitoring

    NASA Astrophysics Data System (ADS)

    Cermak, Vladimir; Safanda, Jan; Kresl, Milan

    2008-01-01

    SummaryIntra-hole convection was monitored in detail by a string of five high resolution temperature probes arranged in an 8-m long unit lowered step-by-step into a slim experimental borehole. The experiment was performed in the test hole Sporilov (Prague). A 50-m long depth interval (between 80 and 130 m) was covered in five successive steps. The hole itself is 150 m deep and 112 mm in diameter. The experiment occurred in the internal plastic tube 5 cm in diameter which is sealed from the influx of ground water in the surrounding strata. In the studied interval the temperature gradient varies in the range of 0.020-0.0215 K/m. The borehole was drilled in 1993 and has been in equilibrium since then. Temperature as a function of time was sampled in 15 s intervals and the individual measuring steps took from 1.5 to 2.5 days, each temperature time series thus contained 9000 up to 16,000 data points. The obtained results revealed: (1) temperature-time series present a complex apparently random oscillation pattern with the amplitude of up to 0.045 K; (2) the statistical analysis confirmed a quasi-periodic skeleton of a two-frequency oscillation structure. Shorter periods of 10 up to 30 min are superposed on longer variations with period of several hours. (3) The quasi-periodicity may be hidden under a considerable amount of noise. (4) Within the studied interval the quasi-periodic convection may alternate with a relatively "quiet" regime when temperature oscillations decreased to only 0.004-0.01 K range. (5) Regardless of certain deterministic rules present in the dynamics, the bulk of temperature variations are chaotic.

  8. Resolution of ray-finned fish phylogeny and timing of diversification

    PubMed Central

    Near, Thomas J.; Eytan, Ron I.; Dornburg, Alex; Kuhn, Kristen L.; Moore, Jon A.; Davis, Matthew P.; Wainwright, Peter C.; Friedman, Matt; Smith, W. Leo

    2012-01-01

    Ray-finned fishes make up half of all living vertebrate species. Nearly all ray-finned fishes are teleosts, which include most commercially important fish species, several model organisms for genomics and developmental biology, and the dominant component of marine and freshwater vertebrate faunas. Despite the economic and scientific importance of ray-finned fishes, the lack of a single comprehensive phylogeny with corresponding divergence-time estimates has limited our understanding of the evolution and diversification of this radiation. Our analyses, which use multiple nuclear gene sequences in conjunction with 36 fossil age constraints, result in a well-supported phylogeny of all major ray-finned fish lineages and molecular age estimates that are generally consistent with the fossil record. This phylogeny informs three long-standing problems: specifically identifying elopomorphs (eels and tarpons) as the sister lineage of all other teleosts, providing a unique hypothesis on the radiation of early euteleosts, and offering a promising strategy for resolution of the “bush at the top of the tree” that includes percomorphs and other spiny-finned teleosts. Contrasting our divergence time estimates with studies using a single nuclear gene or whole mitochondrial genomes, we find that the former underestimates ages of the oldest ray-finned fish divergences, but the latter dramatically overestimates ages for derived teleost lineages. Our time-calibrated phylogeny reveals that much of the diversification leading to extant groups of teleosts occurred between the late Mesozoic and early Cenozoic, identifying this period as the “Second Age of Fishes.” PMID:22869754

  9. Particle Identification Using Cost Effective mRPC Technology for Time-of-Flight Measurements with Less than 10 ps Time Resolution

    NASA Astrophysics Data System (ADS)

    Shimek, Taylor

    2015-10-01

    This presentation will introduce the use of multi-gap Resistive Plate Chambers (mRPCs) for time of flight (TOF) based particle identification (PID) in nuclear and high-energy physics. The mRPC technology is developed for use in future experiments at the planned Electron Ion Collider, EIC. TOF PID using mRPCs with 10 ps timing resolution will make it possible to precisely determine the flavor content of valence- and sea-quarks in the proton through semi-inclusive deep inelastic scattering with identified pions and kaons. A first mRPC prototype using float glass resistive plates at UIUC has reached a timing resolution of 21 ps. In this presentation I discuss an effort to replace the float glass with cheaper Mylar-based resistive plates. I will also discuss the design and construction of a first prototype and present initial results on signal development, efficiencies and timing resolution of the mRPC prototype.

  10. Reconstruction of air shower muon densities using segmented counters with time resolution

    NASA Astrophysics Data System (ADS)

    Ravignani, D.; Supanitsky, A. D.; Melo, D.

    2016-09-01

    Despite the significant experimental effort made in the last decades, the origin of the ultra-high energy cosmic rays is still largely unknown. Key astrophysical information to identify where these energetic particles come from is provided by their chemical composition. It is well known that a very sensitive tracer of the primary particle type is the muon content of the showers generated by the interaction of the cosmic rays with air molecules. We introduce a likelihood function to reconstruct particle densities using segmented detectors with time resolution. As an example of this general method, we fit the muon distribution at ground level using an array of counters like AMIGA, one of the Pierre Auger Observatory detectors. For this particular case we compare the reconstruction performance against a previous method. With the new technique, more events can be reconstructed than before. In addition the statistical uncertainty of the measured number of muons is reduced, allowing for a better discrimination of the cosmic ray primary mass.

  11. High-time resolution and size-segregated elemental composition in high-intensity pyrotechnic exposures.

    PubMed

    Crespo, Javier; Yubero, Eduardo; Nicolás, Jose F; Lucarelli, Franco; Nava, Silvia; Chiari, Massimo; Calzolai, Giulia

    2012-11-30

    Typical of festivals in Eastern Spain, mascletàs are high-intensity pyrotechnic events where thousands of firecrackers are burnt in an intense, rapid episode that generates short-lived heavy aerosol clouds. High temporal resolution and size distribution characterisation of aerosol components were performed to evaluate the effects of the brief (<30 min) and acute exposure on the spectators present. Very high concentrations of firework specific elements, especially in the fine fraction, were reached during mascletàs, with values of about 500 μg/m(3) for K and 300 μg/m(3) for Cl. Sr, Al, Mg, Ba, Cu, Co, Zn, and Pb concentration increase factors of more than 100 (1000 for Sr and Ba) were observed in the fine fraction with respect to background levels. Crustal origin elements, like Ca, Fe, Si, Ti, also showed an important concentration rise (~10 times above background levels) but this is due to dust resuspension by pyrotechnic explosions. The crustal components are mainly in the coarse mode (>90% elemental mass), between 2 and 3 μm. Most firework related metals are concentrated in the submicrometric region (>80%) with a trimodal size distribution. This may be interesting to epidemiologists given the toxic effects that such fine, metal-rich particles can have on human health. PMID:23026448

  12. Mapping forest fuels through vegetation phenology: the role of coarse-resolution satellite time-series.

    PubMed

    Bajocco, Sofia; Dragoz, Eleni; Gitas, Ioannis; Smiraglia, Daniela; Salvati, Luca; Ricotta, Carlo

    2015-01-01

    Traditionally fuel maps are built in terms of 'fuel types', thus considering the structural characteristics of vegetation only. The aim of this work is to derive a phenological fuel map based on the functional attributes of coarse-scale vegetation phenology, such as seasonality and productivity. MODIS NDVI 250 m images of Sardinia (Italy), a large Mediterranean island with high frequency of fire incidence, were acquired for the period 2000-2012 to construct a mean annual NDVI profile of the vegetation at the pixel-level. Next, the following procedure was used to develop the phenological fuel map: (i) image segmentation on the Fourier components of the NDVI profiles to identify phenologically homogeneous landscape units, (ii) cluster analysis of the phenological units and post-hoc analysis of the fire-proneness of the phenological fuel classes (PFCs) obtained, (iii) environmental characterization (in terms of land cover and climate) of the PFCs. Our results showed the ability of coarse-resolution satellite time-series to characterize the fire-proneness of Sardinia with an adequate level of accuracy. The remotely sensed phenological framework presented may represent a suitable basis for the development of fire distribution prediction models, coarse-scale fuel maps and for various biogeographic studies.

  13. High time resolution observations of HF cross-modulation within the D region ionosphere

    NASA Astrophysics Data System (ADS)

    Langston, J.; Moore, R. C.

    2013-05-01

    High-frequency cross-modulation is employed to probe the D region ionosphere during HF heating experiments at the High-frequency Active Auroral Research Program (HAARP) observatory. We have adapted Fejer's well-known cross-modulation probing method to determine the extent of ionospheric conductivity modification in the D region ionosphere with high (5 μsec) time resolution. We demonstrate that the method can be used to analyze D region conductivity changes produced by HF heating both during the initial stages of heating and under steady state conditions. The sequence of CW probe pulses used allow the separation of cross-modulation effects that occur as the probe pulse propagates upward and downward through the heated region. We discuss how this probing technique can be applied to benefit ELF/VLF wave generation experiments and ionospheric irregularities experiments at higher altitudes. We demonstrate that large phase changes equivalent to Doppler shift velocities >60 km/s can be imposed on HF waves propagating through the heated D region ionosphere.

  14. Mapping forest fuels through vegetation phenology: the role of coarse-resolution satellite time-series.

    PubMed

    Bajocco, Sofia; Dragoz, Eleni; Gitas, Ioannis; Smiraglia, Daniela; Salvati, Luca; Ricotta, Carlo

    2015-01-01

    Traditionally fuel maps are built in terms of 'fuel types', thus considering the structural characteristics of vegetation only. The aim of this work is to derive a phenological fuel map based on the functional attributes of coarse-scale vegetation phenology, such as seasonality and productivity. MODIS NDVI 250 m images of Sardinia (Italy), a large Mediterranean island with high frequency of fire incidence, were acquired for the period 2000-2012 to construct a mean annual NDVI profile of the vegetation at the pixel-level. Next, the following procedure was used to develop the phenological fuel map: (i) image segmentation on the Fourier components of the NDVI profiles to identify phenologically homogeneous landscape units, (ii) cluster analysis of the phenological units and post-hoc analysis of the fire-proneness of the phenological fuel classes (PFCs) obtained, (iii) environmental characterization (in terms of land cover and climate) of the PFCs. Our results showed the ability of coarse-resolution satellite time-series to characterize the fire-proneness of Sardinia with an adequate level of accuracy. The remotely sensed phenological framework presented may represent a suitable basis for the development of fire distribution prediction models, coarse-scale fuel maps and for various biogeographic studies. PMID:25822505

  15. A high resolution electrostatic time-of-flight spectrometer with adiabatic magnetic collimation

    NASA Astrophysics Data System (ADS)

    Bonn, J.; Bornschein, L.; Degen, B.; Otten, E. W.; Weinheimer, Ch

    1999-01-01

    A new type of spectrometer for low energy charged particles is presented. It consists of an adiabatic magnetic collimation and two filters: an electrostatic retarding potential to set a lower limit (high pass) and a time-of-flight analysis to reject high energy charged particles (low pass). Both filters are only limited in their resolution by the efficiency of the adiabatic magnetic collimation. The proof of this principle is demonstrated by a pilot measurement on the K conversion line of 83mKr. Possible applications to pulsed and continuous electron sources are discussed with the emphasis on the investigation of the β spectrum of T 2 to deduce information on the mass of the electron antineutrino and possible anomalies in the β spectrum. In this context design parameters of a spectrometer with a resolving power of E/ ΔE=20 000 and a luminosity of A ΔΩ/4 π=4 cm2 for 20 keV electrons are given.

  16. High-time resolution and size-segregated elemental composition in high-intensity pyrotechnic exposures.

    PubMed

    Crespo, Javier; Yubero, Eduardo; Nicolás, Jose F; Lucarelli, Franco; Nava, Silvia; Chiari, Massimo; Calzolai, Giulia

    2012-11-30

    Typical of festivals in Eastern Spain, mascletàs are high-intensity pyrotechnic events where thousands of firecrackers are burnt in an intense, rapid episode that generates short-lived heavy aerosol clouds. High temporal resolution and size distribution characterisation of aerosol components were performed to evaluate the effects of the brief (<30 min) and acute exposure on the spectators present. Very high concentrations of firework specific elements, especially in the fine fraction, were reached during mascletàs, with values of about 500 μg/m(3) for K and 300 μg/m(3) for Cl. Sr, Al, Mg, Ba, Cu, Co, Zn, and Pb concentration increase factors of more than 100 (1000 for Sr and Ba) were observed in the fine fraction with respect to background levels. Crustal origin elements, like Ca, Fe, Si, Ti, also showed an important concentration rise (~10 times above background levels) but this is due to dust resuspension by pyrotechnic explosions. The crustal components are mainly in the coarse mode (>90% elemental mass), between 2 and 3 μm. Most firework related metals are concentrated in the submicrometric region (>80%) with a trimodal size distribution. This may be interesting to epidemiologists given the toxic effects that such fine, metal-rich particles can have on human health.

  17. Time-resolved photoemission apparatus achieving sub-20-meV energy resolution and high stability

    SciTech Connect

    Ishida, Y.; Togashi, T.; Yamamoto, K.; Tanaka, M.; Kiss, T.; Otsu, T.; Kobayashi, Y.; Shin, S.

    2014-12-15

    The paper describes a time- and angle-resolved photoemission apparatus consisting of a hemispherical analyzer and a pulsed laser source. We demonstrate 1.48-eV pump and 5.92-eV probe measurements at the ⩾10.5-meV and ⩾240-fs resolutions by use of fairly monochromatic 170-fs pulses delivered from a regeneratively amplified Ti:sapphire laser system operating typically at 250 kHz. The apparatus is capable to resolve the optically filled superconducting peak in the unoccupied states of a cuprate superconductor, Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+δ}. A dataset recorded on Bi(111) surface is also presented. Technical descriptions include the followings: A simple procedure to fine-tune the spatio-temporal overlap of the pump-and-probe beams and their diameters; achieving a long-term stability of the system that enables a normalization-free dataset acquisition; changing the repetition rate by utilizing acoustic optical modulator and frequency-division circuit.

  18. Carotenoid-bacteriochlorophyll energy transfer in LH2 complexes studied with 10-fs time resolution.

    PubMed

    Polli, Dario; Cerullo, Giulio; Lanzani, Guglielmo; De Silvestri, Sandro; Hashimoto, Hideki; Cogdell, Richard J

    2006-04-01

    In this report, we present a study of carotenoid-bacteriochlorophyll energy transfer processes in two peripheral light-harvesting complexes (known as LH2) from purple bacteria. We use transient absorption spectroscopy with approximately 10 fs temporal resolution, which is necessary to observe the very fast energy relaxation processes. By comparing excited-state dynamics of the carotenoids in organic solvents and inside the LH2 complexes, it has been possible to directly evaluate their energy transfer efficiency to the bacteriochlorophylls. In the case of okenone in the LH2 complex from Chromatium purpuratum, we obtained an energy transfer efficiency of etaET2=63+/-2.5% from the optically active excited state (S2) and etaET1=61+/-2% from the optically dark state (S1); for rhodopin glucoside contained in the LH2 complex from Rhodopseudomonas acidophila these values become etaET2=49.5+/-3.5% and etaET1=5.1+/-1%. The measurements also enabled us to observe vibrational energy relaxation in the carotenoids' S1 state and real-time collective vibrational coherence initiated by the ultrashort pump pulses. Our results are important for understanding the dynamics of early events of photosynthesis and relating it to the structural arrangement of the chromophores.

  19. Neighborhood factors associated with time to resolution following an abnormal breast or cervical cancer screening test

    PubMed Central

    Plascak, Jesse J.; Llanos, Adana A.; Pennell, Michael L.; Weier, Rory C.; Paskett, Electra D.

    2014-01-01

    Background The effect of neighborhood and healthcare access factors on cancer outcomes among patients enrolled in navigator programs is not clearly understood. This study assessed associations between: 1) neighborhood factors and diagnostic time to resolution (TTR) and, 2) geographic access and TTR following an abnormal breast or cervical cancer screening test among women participating in the Ohio Patient Navigator Research Program (OPNRP). Methods Patient (demographic, socioeconomic status [SES], home-to-clinic distance) and neighborhood (deprivation, racial segregation) characteristics of 801 women living in one of 285 census tracts (CTs) in greater Columbus, Ohio were examined. Randomization to receive navigation occurred at the clinic level. Multilevel Cox regression and spatial analysis were used to estimate effects of various factors on TTR and assess model assumptions, respectively. Results TTR increased as neighborhood deprivation increased. After adjustment for age, friend social support, education and healthcare status, the TTR among women living in a neighborhood with a moderate median household income (between $36,147 and $53,099) was shorter compared to women living in low median household income neighborhoods (< $36,147) (p < 0.05). There is little evidence that unmeasured confounders are geographically patterned. Conclusions Increased neighborhood socioeconomic deprivation was associated with longer TTR following an abnormal breast or cervical cancer screening test. Impact These results highlight the need for addressing patient- and neighborhood-level factors to reduce cancer disparities among underserved populations. PMID:25205516

  20. Mapping Forest Fuels through Vegetation Phenology: The Role of Coarse-Resolution Satellite Time-Series

    PubMed Central

    Bajocco, Sofia; Dragoz, Eleni; Gitas, Ioannis; Smiraglia, Daniela; Salvati, Luca; Ricotta, Carlo

    2015-01-01

    Traditionally fuel maps are built in terms of ‘fuel types’, thus considering the structural characteristics of vegetation only. The aim of this work is to derive a phenological fuel map based on the functional attributes of coarse-scale vegetation phenology, such as seasonality and productivity. MODIS NDVI 250m images of Sardinia (Italy), a large Mediterranean island with high frequency of fire incidence, were acquired for the period 2000–2012 to construct a mean annual NDVI profile of the vegetation at the pixel-level. Next, the following procedure was used to develop the phenological fuel map: (i) image segmentation on the Fourier components of the NDVI profiles to identify phenologically homogeneous landscape units, (ii) cluster analysis of the phenological units and post-hoc analysis of the fire-proneness of the phenological fuel classes (PFCs) obtained, (iii) environmental characterization (in terms of land cover and climate) of the PFCs. Our results showed the ability of coarse-resolution satellite time-series to characterize the fire-proneness of Sardinia with an adequate level of accuracy. The remotely sensed phenological framework presented may represent a suitable basis for the development of fire distribution prediction models, coarse-scale fuel maps and for various biogeographic studies. PMID:25822505

  1. BALLOON-BASED HIGH-TIME RESOLUTION MEASUREMENTS OF X-RAY EMISSIONS FROM LIGHTNING

    SciTech Connect

    K. EACK; D. SUSZCYNSKY; ET AL

    2000-08-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project consisted of a series of balloon flights to collect high-time-resolution x-ray and electric-field-change measurements in thunderstorms in order to validate the existence of the runaway air-breakdown mechanism during lightning and/or sprite production. The runaway air-breakdown mechanism is currently the leading theory to account for unexplained balloon and aircraft-based measurements of x-ray enhancements associated with sprites. Balloon-borne gamma-ray and electric-field-change instruments were launched into a daytime summer thunderstorm. A greater than three-fold increase in the gamma-ray flux was observed as the balloon descended through a thunderstorm anvil where a strong electric field was present. These observations suggest that gamma-ray production in thunderstorms may not be as uncommon as previously believed.

  2. High-resolution, near-real-time x-ray video imaging without image intensification

    NASA Astrophysics Data System (ADS)

    Mengers, Paul

    1993-12-01

    This paper discusses a type of x-ray camera designed to generate standard RS-170 video output that does not use x-ray or optical image intensifiers. Instead, it employs a very sensitive, very high resolution CCD sensor which views an x-ray-to-light conversion screen directly through a high speed imaging lens. This new solid state TV camera, which is described later, has very low readout noise plus unusually high gain which enables it to generate real-time video with incident flux levels typical of many inspection applications. Perhaps more important is an ability to integrate for multiple frame intervals on the chip followed by the output of a standard, RS-170 format video frame containing two balanced interlaced fields. In this integrating mode excellent quality images of low contrast objects can be obtained with only a few tenths of a second integration intervals. The basic elements of this type of camera are described and applications discussed where this approach appears to have important advantages over other methods in common use.

  3. The effect of the rotational angle on MR diffusion indices in nerves: Is the rms displacement of the slow-diffusing component a good measure of fiber orientation?

    NASA Astrophysics Data System (ADS)

    Bar-Shir, Amnon; Cohen, Yoram

    2008-01-01

    In recent years, much effort has been made to increase our ability to infer nerve fiber direction through the use of diffusion MR. The present study examines the effect of the rotational angle ( α), i.e. the angle between the diffusion sensitizing gradients and the main axis of the fibers in the nerves, on different NMR indices. The indices examined were the apparent diffusion coefficient (ADC), extracted from low b-values ( bmax ≈ 1200 s/mm 2), and the root mean square (rms) displacement of the fast and the slow-diffusing components extracted from high b-value q-space diffusion MR data. In addition, the effect of both the diffusion time and myelination was evaluated. We found that the most sensitive index to the rotational angle is the rms displacement of the slow-diffusing component extracted from the high b-value q-space diffusion MR experiment. For this component the rms displacement was nearly constant for α values ranging from -10° to +80° (where α = 0° is the z direction), but it changed dramatically when diffusion was measured nearly perpendicular to the nerve fiber direction, i.e., for α = 90 ± 10°. The ADC and the rms displacement of the fast-diffusing component exhibited only gradual changes, with a maximal change at α = 45 ± 15°. The sensitivity of the rms displacement of the slow-diffusing component to the rotational angle was found to be higher at longer diffusion times and in mature fully myelinated nerves. The relevance of these observations for determining the fiber direction is briefly discussed.

  4. High resolution crustal image of South California Continental Borderland: Reverse time imaging including multiples

    NASA Astrophysics Data System (ADS)

    Bian, A.; Gantela, C.

    2014-12-01

    Strong multiples were observed in marine seismic data of Los Angeles Regional Seismic Experiment (LARSE).It is crucial to eliminate these multiples in conventional ray-based or one-way wave-equation based depth image methods. As long as multiples contain information of target zone along travelling path, it's possible to use them as signal, to improve the illumination coverage thus enhance the image quality of structural boundaries. Reverse time migration including multiples is a two-way wave-equation based prestack depth image method that uses both primaries and multiples to map structural boundaries. Several factors, including source wavelet, velocity model, back ground noise, data acquisition geometry and preprocessing workflow may influence the quality of image. The source wavelet is estimated from direct arrival of marine seismic data. Migration velocity model is derived from integrated model building workflow, and the sharp velocity interfaces near sea bottom needs to be preserved in order to generate multiples in the forward and backward propagation steps. The strong amplitude, low frequency marine back ground noise needs to be removed before the final imaging process. High resolution reverse time image sections of LARSE Lines 1 and Line 2 show five interfaces: depth of sea-bottom, base of sedimentary basins, top of Catalina Schist, a deep layer and a possible pluton boundary. Catalina Schist shows highs in the San Clemente ridge, Emery Knoll, Catalina Ridge, under Catalina Basin on both the lines, and a minor high under Avalon Knoll. The high of anticlinal fold in Line 1 is under the north edge of Emery Knoll and under the San Clemente fault zone. An area devoid of any reflection features are interpreted as sides of an igneous plume.

  5. High-Resolution Time-Frequency Spectrum-Based Lung Function Test from a Smartphone Microphone

    PubMed Central

    Thap, Tharoeun; Chung, Heewon; Jeong, Changwon; Hwang, Ki-Eun; Kim, Hak-Ryul; Yoon, Kwon-Ha; Lee, Jinseok

    2016-01-01

    In this paper, a smartphone-based lung function test, developed to estimate lung function parameters using a high-resolution time-frequency spectrum from a smartphone built-in microphone is presented. A method of estimation of the forced expiratory volume in 1 s divided by forced vital capacity (FEV1/FVC) based on the variable frequency complex demodulation method (VFCDM) is first proposed. We evaluated our proposed method on 26 subjects, including 13 healthy subjects and 13 chronic obstructive pulmonary disease (COPD) patients, by comparing with the parameters clinically obtained from pulmonary function tests (PFTs). For the healthy subjects, we found that an absolute error (AE) and a root mean squared error (RMSE) of the FEV1/FVC ratio were 4.49% ± 3.38% and 5.54%, respectively. For the COPD patients, we found that AE and RMSE from COPD patients were 10.30% ± 10.59% and 14.48%, respectively. For both groups, we compared the results using the continuous wavelet transform (CWT) and short-time Fourier transform (STFT), and found that VFCDM was superior to CWT and STFT. Further, to estimate other parameters, including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and peak expiratory flow (PEF), regression analysis was conducted to establish a linear transformation. However, the parameters FVC, FEV1, and PEF had correlation factor r values of 0.323, 0.275, and −0.257, respectively, while FEV1/FVC had an r value of 0.814. The results obtained suggest that only the FEV1/FVC ratio can be accurately estimated from a smartphone built-in microphone. The other parameters, including FVC, FEV1, and PEF, were subjective and dependent on the subject’s familiarization with the test and performance of forced exhalation toward the microphone. PMID:27548164

  6. High-Resolution Time-Frequency Spectrum-Based Lung Function Test from a Smartphone Microphone.

    PubMed

    Thap, Tharoeun; Chung, Heewon; Jeong, Changwon; Hwang, Ki-Eun; Kim, Hak-Ryul; Yoon, Kwon-Ha; Lee, Jinseok

    2016-01-01

    In this paper, a smartphone-based lung function test, developed to estimate lung function parameters using a high-resolution time-frequency spectrum from a smartphone built-in microphone is presented. A method of estimation of the forced expiratory volume in 1 s divided by forced vital capacity (FEV₁/FVC) based on the variable frequency complex demodulation method (VFCDM) is first proposed. We evaluated our proposed method on 26 subjects, including 13 healthy subjects and 13 chronic obstructive pulmonary disease (COPD) patients, by comparing with the parameters clinically obtained from pulmonary function tests (PFTs). For the healthy subjects, we found that an absolute error (AE) and a root mean squared error (RMSE) of the FEV₁/FVC ratio were 4.49% ± 3.38% and 5.54%, respectively. For the COPD patients, we found that AE and RMSE from COPD patients were 10.30% ± 10.59% and 14.48%, respectively. For both groups, we compared the results using the continuous wavelet transform (CWT) and short-time Fourier transform (STFT), and found that VFCDM was superior to CWT and STFT. Further, to estimate other parameters, including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), and peak expiratory flow (PEF), regression analysis was conducted to establish a linear transformation. However, the parameters FVC, FEV1, and PEF had correlation factor r values of 0.323, 0.275, and -0.257, respectively, while FEV₁/FVC had an r value of 0.814. The results obtained suggest that only the FEV1/FVC ratio can be accurately estimated from a smartphone built-in microphone. The other parameters, including FVC, FEV1, and PEF, were subjective and dependent on the subject's familiarization with the test and performance of forced exhalation toward the microphone. PMID:27548164

  7. How can audiovisual pathways enhance the temporal resolution of time-compressed speech in blind subjects?

    PubMed

    Hertrich, Ingo; Dietrich, Susanne; Ackermann, Hermann

    2013-01-01

    In blind people, the visual channel cannot assist face-to-face communication via lipreading or visual prosody. Nevertheless, the visual system may enhance the evaluation of auditory information due to its cross-links to (1) the auditory system, (2) supramodal representations, and (3) frontal action-related areas. Apart from feedback or top-down support of, for example, the processing of spatial or phonological representations, experimental data have shown that the visual system can impact auditory perception at more basic computational stages such as temporal signal resolution. For example, blind as compared to sighted subjects are more resistant against backward masking, and this ability appears to be associated with activity in visual cortex. Regarding the comprehension of continuous speech, blind subjects can learn to use accelerated text-to-speech systems for "reading" texts at ultra-fast speaking rates (>16 syllables/s), exceeding by far the normal range of 6 syllables/s. A functional magnetic resonance imaging study has shown that this ability, among other brain regions, significantly covaries with BOLD responses in bilateral pulvinar, right visual cortex, and left supplementary motor area. Furthermore, magnetoencephalographic measurements revealed a particular component in right occipital cortex phase-locked to the syllable onsets of accelerated speech. In sighted people, the "bottleneck" for understanding time-compressed speech seems related to higher demands for buffering phonological material and is, presumably, linked to frontal brain structures. On the other hand, the neurophysiological correlates of functions overcoming this bottleneck, seem to depend upon early visual cortex activity. The present Hypothesis and Theory paper outlines a model that aims at binding these data together, based on early cross-modal pathways that are already known from various audiovisual experiments on cross-modal adjustments during space, time, and object recognition. PMID

  8. Investigating catchment-scale hysteretic behaviour of nutrients at annual and individual storm time-resolutions.

    NASA Astrophysics Data System (ADS)

    Lloyd, Charlotte; Freer, Jim; Johnes, Penny; Collins, Adrian

    2013-04-01

    The European Water Framework Directive (WFD) requires that all water bodies should be maintained at, or raised to, good ecological status, driven by improved integrated catchment management. Therefore, it is necessary to implement cost-effective mitigation strategies to reduce pollution from nutrients and improve overall water quality. If successful mitigation strategies are to be designed then it is imperative that catchment scale responses to environmental and anthropogenic changes are better understood. Against this background, this presentation investigates changes in hysteretic behaviours of nutrients in response to different environmental drivers using high resolution monitoring techniques. Observations of hysteretic behaviour can provide insights into the dominant flow pathways of pollutants. Therefore, monitoring changes in nutrient hysteresis can provide a useful tool for detecting regime differences or changes within and between catchments. In the UK, the Demonstration Test Catchment (DTC) project has been set up to monitor evidence for improving water quality problems arising specifically from diffuse pollution from agriculture using targeted mitigation experiments and high resolution monitoring. This research platform provides an opportunity to compare storm-driven nutrient behaviour between catchments which have differing geologies, as well as how these behaviours evolve on a seasonal and annual basis. The monitoring to date has included a period of drought, directly followed by extreme wet conditions in the UK and therefore offers opportunities to assess the effect of differences in antecedent conditions on monitored nutrient response to rainfall events. The study compares the hysteretic behaviour of nutrients, including nitrogen and phosphorus species as well as sediment from a number of storm events of varying magnitudes throughout the 2011-2012 monitoring period in the Hampshire Avon catchment as part of the DTC programme. The investigation focuses

  9. STS-31 Hubble Space Telescope (HST) (SAs and HGAs deployed) is grappled by RMS

    NASA Technical Reports Server (NTRS)

    1990-01-01

    During STS-31, the Hubble Space Telescope (HST), still in the grasp of Discovery's, Orbiter Vehicle (OV) 103's, remote manipulator system (RMS), is backdropped over the Earth some 332 nautical miles below. In this scene, HST's starboard solar array (SA) wing and two high gain antennae (HGA) are fully extended. An aft flight deck window frames the scene.

  10. Astronaut Jeffrey Hoffman on RMS during third of five HST EVAs

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Astronaut Jeffrey A. Hoffman signals directions to Swiss Astronaut Claude Nicollier, as the latter controls the Remote Manipulator System (RMS) arm during the third of five space walks on the Hubble Space Telescope (HST) servicing mission. A portion of the Earth's surface can be seen directly behind him.

  11. Astronaut James van Hoften on RMS tracking Syncom IV-3 after deployment

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Astronaut James D. van Hoften on the Discovery's remote manipulator system (RMS) visually tracking the Syncom IV-3 communications satellite after its second release. The satellite is partially visible at the edge of the frame. Clouds over the ocean form the backdrop.

  12. View of the ASEM structure manipulated by the RMS above the payload bay.

    NASA Technical Reports Server (NTRS)

    1992-01-01

    View of the Assembly of Station by EVA Methods (ASEM) structure manipulated by the Remote Manipulator System (RMS) above the payload bay with EVA Mission Specialists Kathy Thornton (dashed red stripe) and Tom Akers (red diagonal stripes) working on the suspended structure.

  13. Astronaut Sherwood Spring on RMS checks joints on the ACCESS device

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Astronaut Sherwood C. Spring, anchored to the foot restraint on the remote manipulator system (RMS) arm, checks joints on the tower-like Assembly Concept for Construction of Erectable Space Structures (ACCESS) device extending from the payload bay as the Atlantis flies over white clouds and blue ocean waters. The Gulf of Mexico waters form the backdrop for the scene.

  14. Hubble Space Telescoe being surveyed by cameras mounted on the RMS

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The Hubble Space Telescope (HST) is backdropped against the blackness of space in this 70mm frame recorded during a video survey of the spacecraft following the telescope's berthing in Endeavour's cargo bay. Swiss scientist Claude Nicollier controlled the Remote Manipulator System (RMS) arm slowly so that mounted TV cameras could show flight controllers the various areas on the telescope.

  15. Astronaut Claude Nicollier on flight deck at controls of the RMS

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Swiss Astronaut Claude Nicollier, mission specialist, is stationed on Endeavour's flight deck during one of the five Hubble Space Telescope (HST) servicing space walks. The controls for the Remote Manipulator System (RMS) are left of frame center. Two space walkers can be seen through the aft windows.

  16. Limits On Rms Radio Source Contributions To The Microwave Sky Set By WMAP

    NASA Astrophysics Data System (ADS)

    Partridge, R. Bruce; Boughn, S.

    2007-12-01

    Cross correlations between the WMAP full sky K, Ka, Q, V, and W-band maps with the 1.4 GHz NVSS source count map and the HEAO I A2 2-10 keV full sky X-ray flux map are used to constrain rms fluctuations due to unresolved & undetected microwave sources in the WMAP frequency range. In the Q band (40.7 GHz), a lower limit, taking account only of those fluctuations correlated with the 1.4 GHz radio counts and the X-ray flux, corresponds to an rms Rayleigh-Jeans temperature of 2μK for a solid angle of one square degree. The correlated fluctuations at the other bands are consistent with a α = -0.1 ± 0.4 frequency spectrum. Using the rms fluctuations of X-ray flux and radio source flux, and the cross correlation of these two quantities as a guide, the above lower limit leads to a plausible estimate of 5μK for Q-band rms fluctuations in one square degree. This value is similar to that implied by the excess, small angular scale, Q-band fluctuations observed by WMAP, and is consistent with estimates made by extrapolating low-frequency source counts.

  17. A Historical Study to Understand Students' Current Difficulties about RMS Values

    ERIC Educational Resources Information Center

    Khantine-Langlois, Françoise; Munier, Valérie

    2016-01-01

    Several studies show that students experience more and more difficulties managing the measurements of electrical values in alternating current and that they have trouble making links between theory and practice. They find it difficult to give meaning to root mean square (RMS; or effective) values, which are not understood as average values and are…

  18. Rule-based approach to operating system selection: RMS vs. UNIX

    SciTech Connect

    Phifer, M.S.; Sadlowe, A.R.; Emrich, M.L.; Gadagkar, H.P.

    1988-10-01

    A rule-based system is under development for choosing computer operating systems. Following a brief historical account, this paper compares and contrasts the essential features of two operating systems highlighting particular applications. ATandT's UNIX System and Datapoint Corporations's Resource Management System (RMS) are used as illustrative examples. 11 refs., 3 figs.

  19. RMS Spectral Modelling - a powerful tool to probe the origin of variability in Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Mallick, Labani; Dewangan, Gulab chand; Misra, Ranjeev

    2016-07-01

    The broadband energy spectra of Active Galactic Nuclei (AGN) are very complex in nature with the contribution from many ingredients: accretion disk, corona, jets, broad-line region (BLR), narrow-line region (NLR) and Compton-thick absorbing cloud or TORUS. The complexity of the broadband AGN spectra gives rise to mean spectral model degeneracy, e.g, there are competing models for the broad feature near 5-7 keV in terms of blurred reflection and complex absorption. In order to overcome the energy spectral model degeneracy, the most reliable approach is to study the RMS variability spectrum which connects the energy spectrum with temporal variability. The origin of variability could be pivoting of the primary continuum, reflection and/or absorption. The study of RMS (Root Mean Square) spectra would help us to connect the energy spectra with the variability. In this work, we study the energy dependent variability of AGN by developing theoretical RMS spectral model in ISIS (Interactive Spectral Interpretation System) for different input energy spectra. In this talk, I would like to present results of RMS spectral modelling for few radio-loud and radio-quiet AGN observed by XMM-Newton, Suzaku, NuSTAR and ASTROSAT and will probe the dichotomy between these two classes of AGN.

  20. Accuracy of the surface electromyography RMS processing for the diagnosis of myogenous temporomandibular disorder.

    PubMed

    Berni, Kelly Cristina dos Santos; Dibai-Filho, Almir Vieira; Pires, Paulo Fernandes; Rodrigues-Bigaton, Delaine

    2015-08-01

    Due to the multifactor etiology of temporomandibular disorder (TMD), the precise diagnosis remains a matter of debate and validated diagnostic tools are needed. The aim was to determine the accuracy of surface electromyography (sEMG) activity, assessed in the amplitude domain by the root mean square (RMS), in the diagnosis of TMD. One hundred twenty-three volunteers were evaluated using the Research Diagnostic Criteria for Temporomandibular Disorders and distributed into two groups: women with myogenous TMD (n=80) and women without TMD (n=43). The volunteers were then submitted to sEMG evaluation of the anterior temporalis, masseter and suprahyoid muscles at rest and during maximum voluntary teeth clenching (MVC) on parafilm. The accuracy, sensitivity and specificity of the muscle activity were analyzed. Differences between groups were found in all muscles analyzed at rest as well as in the masseter and suprahyoid muscles during MVC on parafilm. Moderate accuracy (AUC: 0.74-0.84) of the RMS sEMG was found in all muscles regarding the diagnosis of TMD at rest and in the suprahyoid muscles during MVC on parafilm. Moreover, sensitivity ranging from 71.3% to 80% and specificity from 60.5% to 76.6%. In contrast, RMS sEMG did not exhibit acceptable degrees of accuracy in the other masticatory muscles during MVC on parafilm. It was concluded that the RMS sEMG is a complementary tool for clinical diagnosis of the myogenous TMD.

  1. EURECA orbits above the Earth's surface prior to STS-57 OV-105 RMS capture

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Backdropped against open ocean waters, the European Retrievable Carrier (EURECA) spacecraft, with solar array (SA) panels folded flat against its sides, approaches Endeavour, Orbiter Vehicle (OV) 105, on flight day five. Later, the remote manipulator system (RMS) end effector was used to 'capture' the spacecraft. After ten days in Earth orbit, the crew returned to Earth, bringing EURECA home.

  2. Monte Carlo Simulation Study on the Time Resolution of a PMT-Quadrant-Sharing LSO Detector Block for Time-of-Flight PET

    PubMed Central

    Liu, Shitao; Li, Hongdi; Zhang, Yuxuan; Ramirez, Rocio A.; Baghaei, Hossain; An, Shaohui; Wang, Chao; Liu, Jiguo; Wong, Wai-Hoi

    2010-01-01

    We developed a detailed Monte Carlo simulation method to study the time resolution of detectors for time-of-flight positron emission tomography (TOF PET). The process of gamma ray interaction in detectors, scintillation light emission and transport inside the detectors, the photoelectron generation and anode signal generation in the photomultiplier tube (PMT), and the electronics process of discriminator are simulated. We tested this simulation method using published experimental data, and found that it can generate reliable results. Using this method, we simulated the time resolution for a 13 × 13 detector block of 4 × 4 × 20 mm3 lutetium orthosilicate (LSO) crystals coupled to four 2-inch PMTs using PMT-quadrant-sharing (PQS) technology. We analyzed the effects of several factors, including the number of photoelectrons, light transport, transit time spread (TTS), and the depth of interaction (DOI). The simulation results indicated that system time resolution of 360 ps should be possible with currently available fast PMTs. This simulation method can also be used to simulate the time resolution of other detector design method. PMID:20559457

  3. Real-Time Variable-Resolution Complementary Metal-Oxide-Semiconductor Field-Effect Transistors Image Sensor

    NASA Astrophysics Data System (ADS)

    Chen, Chih-Yang; Wang, Jian-Jie; Lin, Chrong-Jung; King, Ya-Chin

    2008-04-01

    In this paper, a new, efficient and simple complementary metal-oxide-semiconductor (CMOS) field-effect transistors (FETs) image sensor (CIS) readout architecture providing both real-time variable-resolution image sensing and dynamic range boosting functions is presented. The proposed correlated-double-sampling (CDS) circuit can not only reduce fixed-pattern noise (FPN) but also output the lower resolution image by real-time averaging of four pixels' signals in square 2 ×2 pixels in variable-resolution mode. Variable-resolution imaging can effectively reduce the complexity of the signal process, release the loading of processing units, and accelerate the data processing in motion detection and object tracking operations. In addition, the new CDS circuit can extend dynamic range of a sensor array by analog combining the signals from different integration lengths. The new designed circuits can replace typical CDS readout circuits in typical CIS arrays to provide real-time, accurate resolution-variable imaging and dynamic range boosting without additional overhead on digital circuits.

  4. Theoretical calculations for mass resolution of a quadrupole ion trap reflectron time-of-flight mass spectrometer.

    PubMed

    Choi, Chang Min; Heo, Jiyoung; Park, Chang Joon; Kim, Nam Joon

    2010-02-01

    We have developed a theoretical method of predicting the mass resolution for a quadrupole ion trap reflectron time-of-flight (QIT-reTOF) mass spectrometer as a function of the spatial and velocity distributions of ions, voltages applied to the electrodes, and dimensions of the instrument. The flight times of ions were calculated using theoretical equations derived with an assumption of uniform electric fields inside the QIT and with the analytical description of the potential including the monopole, dipole, and quadrupole components. The mass resolution was then estimated from the flight-time spread of the ions with finite spatial and velocity distributions inside the QIT. The feasibility of the theoretical method was confirmed by the reasonable agreement of the theoretical resolution with the experimental one measured by varying the extraction voltage of the QIT or the deceleration voltage of the reflectron. We found that the theoretical resolution estimated with the assumption of the uniform electric fields inside the QIT reproduced the experimental one better than that with the analytical description of the potential. The possible applications of this theoretical method include the optimization of the experimental parameters of a given QIT-reTOF mass spectrometer and the design of new instruments with higher mass resolution.

  5. High-resolution long-reach distributed Brillouin sensing based on combined time-domain and correlation-domain analysis.

    PubMed

    Elooz, David; Antman, Yair; Levanon, Nadav; Zadok, Avi

    2014-03-24

    A new scheme for distributed Brillouin sensing of strain and temperature in optical fibers is proposed, analyzed and demonstrated experimentally. The technique combines between time-domain and correlation-domain analysis. Both Brillouin pump and signal waves are repeatedly co-modulated by a relatively short, high-rate phase sequence, which introduces Brillouin interactions in a large number of discrete correlation peaks. In addition, the pump wave is also modulated by a single amplitude pulse, which leads to a temporal separation between the generation of different peaks. The Brillouin amplification of the signal wave at individual peak locations is resolved in the time domain. The technique provides the high spatial resolution and long range of unambiguous measurement offered by correlation-domain Brillouin analysis, together with reduced acquisition time through the simultaneous interrogation of a large number of resolution points. In addition, perfect Golomb codes are used in the phase modulation of the two waves instead of random sequences, in order to reduce noise due to residual, off-peak Brillouin interactions. The principle of the method is supported by extensive numerical simulations. Using the proposed scheme, the Brillouin gain spectrum is mapped experimentally along a 400 m-long fiber under test with a spatial resolution of 2 cm, or 20,000 resolution points, with only 127 scans per choice of frequency offset between pump and signal. Compared with corresponding phase-coded, Brillouin correlation domain analysis schemes with equal range and resolution, the acquisition time is reduced by a factor of over 150. A 5 cm-long hot spot, located towards the output end of the pump wave, is properly identified in the measurements. The method represents a significant advance towards practical high-resolution and long range Brillouin sensing systems.

  6. Global system for hydrological monitoring and forecasting in real time at high resolution

    NASA Astrophysics Data System (ADS)

    Ortiz, Enrique; De Michele, Carlo; Todini, Ezio; Cifres, Enrique

    2016-04-01

    This project presented at the EGU 2016 born of solidarity and the need to dignify the most disadvantaged people living in the poorest countries (Africa, South America and Asia, which are continually exposed to changes in the hydrologic cycle suffering events of large floods and/or long periods of droughts. It is also a special year this 2016, Year of Mercy, in which we must engage with the most disadvantaged of our Planet (Gaia) making available to them what we do professionally and scientifically. The project called "Global system for hydrological monitoring and forecasting in real time at high resolution" is Non-Profit and aims to provide at global high resolution (1km2) hydrological monitoring and forecasting in real time and continuously coupling Weather Forecast of Global Circulation Models, such us GFS-0.25° (Deterministic and Ensembles Run) forcing a physically based distributed hydrological model computationally efficient, such as the latest version extended of TOPKAPI model, named TOPKAPI-eXtended. Finally using the MCP approach for the proper use of ensembles for Predictive Uncertainty assessment essentially based on a multiple regression in the Normal space, can be easily extended to use ensembles to represent the local (in time) smaller or larger conditional predictive uncertainty, as a function of the ensemble spread. In this way, each prediction in time accounts for both the predictive uncertainty of the ensemble mean and that of the ensemble spread. To perform a continuous hydrological modeling with TOPKAPI-X model and have hot start of hydrological status of watersheds, the system assimilated products of rainfall and temperature derived from remote sensing, such as product 3B42RT of TRMM NASA and others.The system will be integrated into a Decision Support System (DSS) platform, based on geographical data. The DSS is a web application (For Pc, Tablet/Mobile phone): It does not need installation (all you need is a web browser and an internet

  7. Global system for hydrological monitoring and forecasting in real time at high resolution

    NASA Astrophysics Data System (ADS)

    Ortiz, Enrique; De Michele, Carlo; Todini, Ezio; Cifres, Enrique

    2016-04-01

    This project presented at the EGU 2016 born of solidarity and the need to dignify the most disadvantaged people living in the poorest countries (Africa, South America and Asia, which are continually exposed to changes in the hydrologic cycle suffering events of large floods and/or long periods of droughts. It is also a special year this 2016, Year of Mercy, in which we must engage with the most disadvantaged of our Planet (Gaia) making available to them what we do professionally and scientifically. The project called "Global system for hydrological monitoring and forecasting in real time at high resolution" is Non-Profit and aims to provide at global high resolution (1km2) hydrological monitoring and forecasting in real time and continuously coupling Weather Forecast of Global Circulation Models, such us GFS-0.25° (Deterministic and Ensembles Run) forcing a physically based distributed hydrological model computationally efficient, such as the latest version extended of TOPKAPI model, named TOPKAPI-eXtended. Finally using the MCP approach for the proper use of ensembles for Predictive Uncertainty assessment essentially based on a multiple regression in the Normal space, can be easily extended to use ensembles to represent the local (in time) smaller or larger conditional predictive uncertainty, as a function of the ensemble spread. In this way, each prediction in time accounts for both the predictive uncertainty of the ensemble mean and that of the ensemble spread. To perform a continuous hydrological modeling with TOPKAPI-X model and have hot start of hydrological status of watersheds, the system assimilated products of rainfall and temperature derived from remote sensing, such as product 3B42RT of TRMM NASA and others.The system will be integrated into a Decision Support System (DSS) platform, based on geographical data. The DSS is a web application (For Pc, Tablet/Mobile phone): It does not need installation (all you need is a web browser and an internet

  8. Effect of labeling density and time post labeling on quality of antibody-based super resolution microscopy images

    NASA Astrophysics Data System (ADS)

    Bittel, Amy M.; Saldivar, Isaac; Dolman, Nicholas; Nickerson, Andrew K.; Lin, Li-Jung; Nan, Xiaolin; Gibbs, Summer L.

    2015-03-01

    Super resolution microscopy (SRM) has overcome the historic spatial resolution limit of light microscopy, enabling fluorescence visualization of intracellular structures and multi-protein complexes at the nanometer scale. Using single-molecule localization microscopy, the precise location of a stochastically activated population of photoswitchable fluorophores is determined during the collection of many images to form a single image with resolution of ~10-20 nm, an order of magnitude improvement over conventional microscopy. One of the key factors in achieving such resolution with single-molecule SRM is the ability to accurately locate each fluorophore while it emits photons. Image quality is also related to appropriate labeling density of the entity of interest within the sample. While ease of detection improves as entities are labeled with more fluorophores and have increased fluorescence signal, there is potential to reduce localization precision, and hence resolution, with an increased number of fluorophores that are on at the same time in the same relative vicinity. In the current work, fixed microtubules were antibody labeled using secondary antibodies prepared with a range of Alexa Fluor 647 conjugation ratios to compare image quality of microtubules to the fluorophore labeling density. It was found that image quality changed with both the fluorophore labeling density and time between completion of labeling and performance of imaging study, with certain fluorophore to protein ratios giving optimal imaging results.

  9. Signal Decomposition of High Resolution Time Series River Data to Separate Local and Regional Components of Conductivity

    EPA Science Inventory

    Signal processing techniques were applied to high-resolution time series data obtained from conductivity loggers placed upstream and downstream of an oil and gas wastewater treatment facility along a river. Data was collected over 14-60 days. The power spectral density was us...

  10. : Signal Decomposition of High Resolution Time Series River data to Separate Local and Regional Components of Conductivity

    EPA Science Inventory

    Signal processing techniques were applied to high-resolution time series data obtained from conductivity loggers placed upstream and downstream of a wastewater treatment facility along a river. Data was collected over 14-60 days, and several seasons. The power spectral densit...

  11. Radio frequency phototube and optical clock: High resolution, high rate and highly stable single photon timing technique

    SciTech Connect

    Margaryan, Amur

    2011-10-01

    A new timing technique for single photons based on the radio frequency phototube and optical clock or femtosecond optical frequency comb generator is proposed. The technique has a 20 ps resolution for single photons, is capable of operating with MHz frequencies and achieving 10 fs instability level.

  12. A versatile fluorescence lifetime imaging system for scanning large areas with high time and spatial resolution

    NASA Astrophysics Data System (ADS)

    Bernardo, César; Belsley, Michael; de Matos Gomes, Etelvina; Gonçalves, Hugo; Isakov, Dmitry; Liebold, Falk; Pereira, Eduardo; Pires, Vladimiro; Samantilleke, Anura; Vasilevskiy, Mikhail; Schellenberg, Peter

    2014-08-01

    We present a flexible fluorescence lifetime imaging device which can be employed to scan large sample areas with a spatial resolution adjustable from many micrometers down to sub-micrometers and a temporal resolution of 20 picoseconds. Several different applications of the system will be presented including protein microarrays analysis, the scanning of historical samples, evaluation of solar cell surfaces and nanocrystalline organic crystals embedded in electrospun polymeric nanofibers. Energy transfer processes within semiconductor quantum dot superstructures as well as between dye probes and graphene layers were also investigated.

  13. A measurement of the energy and timing resolution of GlueX Forward Calorimeter using an electron beam

    SciTech Connect

    Moriya, Kei; Leckey, John P.; Shepherd, Matthew R.; Bauer, Kevin; Bennett, Daniel William; Frye, John Michael; Gonzalez, Juan Carlos; Henderson, Scott J.; Lawrence, David W.; Mitchell, Ryan E.; Smith, Elton S.; Smith, Paul T.; Somov, Alexander Sergeyevich; Egiyan, Hovanes

    2013-10-01

    The performance of the GlueX Forward Calorimeter was studied using a small version of the detector and a variable energy electron beam derived from the Hall B tagger at Jefferson Lab. For electron energies from 110 MeV to 260 MeV, which are near the lower-limits of the design sensitivity, the fractional energy resolution was measured to range from 20% to 14%, which meets the design goals. The use of custom 250 MHz flash ADCs for readout allowed precise measurements of signal arrival times. The detector achieved timing resolutions of 0.38 ns for a single 100 mV pulse, which will allow timing discrimination of photon beam bunches and out-of-time background during the operation of the GlueX detector.

  14. STS-48 Upper Atmosphere Research Satellite (UARS) grappled by OV-103's RMS

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The Upper Atmosphere Research Satellite (UARS) is in the grasp of the remote manipulator system (RMS) end effector above the payload bay (PLB) of the Earth-orbiting Discovery, Orbiter Vehicle (OV) 103 during STS-48 pre-deployment checkout procedures. UARS solar array (SA) is in the process of being deployed. Visible on the UARS are (top to bottom): the high-gain antenna (HGA); the Solar Stellar Pointing Platform (SSPP) (below HGA); outrigger truss; the Microwave Limb Sounder (MLS) spectrometer (above SA); the SA; RMS grapple fixture; the Particle Environment Monitor (PEM) Zenith Energetic Particle System (ZEPS) (top next to second outrigger truss); the PEM Nadir Energetic Particle System (NEPS) magnetometer (below ZEPS); an outrigger truss and keel pin; and the Multimission Modular Spacecraft (MSS).

  15. STS-48 Upper Atmosphere Research Satellite (UARS) grappled by OV-103's RMS

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The Upper Atmosphere Research Satellite (UARS), held by Discovery's, Orbiter Vehicle (OV) 103's, remote manipulator system (RMS) end effector, hovers aloft prior to its release from the spacecraft. The solar array (SA) is partially deployed as UARS undergoes STS-48 pre-deployment checkout. UARS components visible in this image include (left to right): the Solar Stellar Pointing Platform (SSPP) (at bottom); the stowed high-gain antenna (HGA) (above SSPP); the Microwave Limb Sounder (MLS) spectrometer; the Cryogenic Limb Array Etalon Spectrometer (CLAES) (top, above RMS end effector); the Particle Environment Monitor (PEM) Zenith Energetic Particle System (ZEPS) (next to outrigger truss); and PEM Nadir Energetic Particle System (NEPS) magnetometer (bottom right). The cloud-covered surface of the Earth is visible below the satellite. This view was taken using an electronic still camera (ESC) as part of Development Test Objective (DTO) 648, Electronic Still Photography. The digital image w

  16. STS-48 Upper Atmosphere Research Satellite (UARS) grappled by OV-103's RMS

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The solar array (SA) of the Upper Atmosphere Research Satellite (UARS), almost completely deployed, is backdropped against the cloud-covered surface of the Earth. During STS-48 pre-deployment checkout, UARS is held above the payload bay (PLB) of Discovery, Orbiter Vehicle (OV) 103, by the remote manipulator system (RMS) end effector (out of frame). The RMS upper arm boom, elbow pitch joint, elbow closed circuit television (CCTV) pan/tilt unit, and lower arm boom are silhouetted against the SA. UARS components visible in this image include (top to bottom): the high-gain antenna (HGA); the Solar Stellar Pointing Platform (SSPP); a keel (pin) trunnion; the Particle Environment Monitor (PEM) Nadir Energetic Particle System (NEPS) magnetometer; a keel (pin) trunnion; and the Multimission Modular Spacecraft (MSS). This view was taken using an electronic still camera (ESC) as part of Development Test Objective (DTO) 648, Electronic Still Photography. The digital image was stored on a removabl

  17. STS-41 ISAC deployed on remote manipulator system (RMS) lower arm boom

    NASA Technical Reports Server (NTRS)

    1990-01-01

    STS-41 International Telecommunications Satellite Organization (INTELSAT) Solar Array Coupon (ISAC) witness plates are mounted on remote manipulator system (RMS) lower arm boom and are exposed to space environment conditions. The RMS with the ISAC material samples is extended above Discovery's, Orbiter Vehicle (OV) 103's, payload bay (PLB) and over the Earth's surface. One witness plate contains an 8.5 x 12-inch solar array coupon and three 5 x 8-inch aluminum plates painted to provide three different temperatures. The second witness plate contains one 8.5 x 12-inch solar array coupon and a 46-position sample holder. This JSC-designed experiment is in preparation for the possible 1992 rescue of INTELSAT-VI, stranded in low orbit earlier this year. Quantitative data on the interaction of atomic oxygen with the solar array silver interconnects and other INTELSAT materials will be obtained.

  18. The pseudonoise test set: Communication system's performance evaluation based upon RMS error testing

    NASA Technical Reports Server (NTRS)

    Wallace, G. R.; Gussow, S. S.; Salter, W. E.; Weathers, G. D.

    1972-01-01

    A pseudonoise (PN) test set was built to provide a relatively easy means of accurately determining the end-to-end rms error introduced by a communication system when subjected to wideband data. It utilizes a filtered pseudorandom sequence generator as a wideband data source, providing a convenient means for digitally delaying the input reference signal for comparison with the distorted test communication system output. In addition to providing a means to measure the end-to-end rms error and the average delay of a communication system, the PN test set also provides a means to determine the tested system's impulse response and correlation function. The theory of PN testing is discussed in detail along with the most difficult aspects of implementation, the building of matched filter pairs. Both analytical and empirical results are reported which support the contentions that this is an accurate and practical way to acquire figures of merit for complete communication systems.

  19. RMS-grappled LDEF is positioned over OV-102's payload bay during STS-32

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Wide angle view looks through aft flight deck viewing window at the Long Duration Exposure Facility (LDEF) grappled by the remote manipulator system (RMS) and positioned vertically above Columbia's, Orbiter Vehicle (OV) 102's, payload bay (PLB). STS-32 crewmembers are conducting a photo survey of LDEF before stowing it in the PLB for its return to Earth. In the background are OV-102's wings, the orbital maneuvering system (OMS) pods, and vertical tail highlighted against the Earth's surface.

  20. STS-31 Hubble Space Telescope (HST) (SA and HGA deployed) is grappled by RMS

    NASA Technical Reports Server (NTRS)

    1990-01-01

    With the starboard solar array (SA) wing and the two high gain antennae (HGA) fully extended, the Hubble Space Telescope (HST) is grappled by Discovery's, Orbiter Vehicle (OV) 103's, remote manipulator system (RMS) during STS-31 predeployment checkout operations. SA bistem cassette and secondary deployment mechanism (SDM) detail is clearly visible. The scene is backdropped against the Earth's limb and cloud-covered surface.

  1. During STS-57, EURECA is grappled by OV-105's RMS end effector

    NASA Technical Reports Server (NTRS)

    1993-01-01

    During STS-57, the European Retrievable Carrier (EURECA) is grappled by Endeavour's, Orbiter Vehicle (OV) 105's, remote manipulator system (RMS) end effector and is held in transfer to retrieval orbit before being stowed in the payload bay (PLB) for return to Earth. The southern two-thirds of the state of Florida, part of the Gulf of Mexico, and clouds over the Atlantic Ocean form the backdrop.

  2. LDEF positioned by RMS over OV-102's payload during STS-32 retrieval

    NASA Technical Reports Server (NTRS)

    1990-01-01

    During STS-32 retrieval activity and photo survey, the Long Duration Exposure Facility (LDEF) is grappled and positioned by remote manipulator system (RMS) over Columbia's, Orbiter Vehicle (OV) 102's, payload bay (PLB). The view was captured through the aft flight deck viewing window and shows the 14 ft (4.3 meter) end of the LDEF spacecraft. The cloud-covered Earth surface appears in the distant background.

  3. Hubble Space Telescope (HST) grappled by OV-103's RMS during STS-31 checkout

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The Hubble Space Telescope (HST), grappled by Discovery's, Orbiter Vehicle (OV) 103's, remote manipulator system (RMS), is held in a pre-deployment position. During STS-31 checkout procedures, the solar array (SA) panels and the high gain antennae (HGA) will be deployed. The starboard SA (center) and the two HGA are stowed along side the Support System Module (SSM) forward shell. The sun highlights HST against the blackness of space.

  4. Combining time of flight and diffraction tomography for high resolution breast imaging: initial in vivo results (L).

    PubMed

    Huthwaite, P; Simonetti, F; Duric, N

    2012-09-01

    Ultrasound tomography (UST) is being developed to address the limitations of mammography in breast cancer detection. Central to the success of UST is the possibility of obtaining high-resolution images of tissue mechanical properties across the whole breast. A recent paper [Huthwaite and Simonetti, J. Acoust. Soc. Am. 130, 1721-1734 (2011)] made use of a numerical phantom to demonstrate that sufficient image resolution can be obtained by simply treating refraction and diffraction effects in consecutive steps through the combination of ray-based time of flight and diffraction tomography. This letter presents the first experimental demonstration of the method using phantom and invivo data from a cancer patient. PMID:22978851

  5. Human interface and transmit frequency control for the through-air acoustic real-time high resolution vision substitute system.

    PubMed

    Taki, Hirofumi; Sato, Toru

    2005-01-01

    Existing vision substitute systems are not useful as navigation system due to the limitation of spatial and time resolution. In this study we propose a transmit control method free from range aliasing for a high resolution acoustic vision substitute systems, which we previously proposed. We also examine a human-machine information transfer method with a vibrotactile stimulator array consisting of 13 × 21 elements. It presents the target area of 30 degree × 60 degree by the sampling interval of 1 degree at the center. The system presents range, direction, and surface topography of targets to the subject.

  6. Very high resolution time-lapse photography for plant and ecosystems research

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Very high resolution gigapixel photography increasingly is being used to support a broad range of ecosystem and physical process research because it offers an inexpensive means of simultaneously collecting information at a range of spatial scales. Recently, methods have been developed to incorporate...

  7. High resolution frequency to time domain transformations applied to the stepped carrier MRIS measurements

    NASA Technical Reports Server (NTRS)

    Ardalan, Sasan H.

    1992-01-01

    Two narrow-band radar systems are developed for high resolution target range estimation in inhomogeneous media. They are reformulations of two presently existing systems such that high resolution target range estimates may be achieved despite the use of narrow bandwidth radar pulses. A double sideband suppressed carrier radar technique originally derived in 1962, and later abandoned due to its inability to accurately measure target range in the presence of an interfering reflection, is rederived to incorporate the presence of an interfering reflection. The new derivation shows that the interfering reflection causes a period perturbation in the measured phase response. A high resolution spectral estimation technique is used to extract the period of this perturbation leading to accurate target range estimates independent of the signal-to-interference ratio. A non-linear optimal signal processing algorithm is derived for a frequency-stepped continuous wave radar system. The resolution enhancement offered by optimal signal processing of the data over the conventional Fourier Transform technique is clearly demonstrated using measured radar data. A method for modeling plane wave propagation in inhomogeneous media based on transmission line theory is derived and studied. Several simulation results including measurement of non-uniform electron plasma densities that develop near the heat tiles of a space re-entry vehicle are presented which verify the validity of the model.

  8. Design and performance evaluation of a high resolution IRI-microPET preclinical scanner

    NASA Astrophysics Data System (ADS)

    Islami rad, S. Z.; Peyvandi, R. Gholipour; lehdarboni, M. Askari; Ghafari, A. A.

    2015-05-01

    PET for small animal, IRI-microPET, was designed and built at the NSTRI. The scanner is made of four detectors positioned on a rotating gantry at a distance 50 mm from the center. Each detector consists of a 10×10 crystal matrix of 2×2×10 mm3 directly coupled to a PS-PMT. A position encoding circuit for specific PS-PMT has been designed, built and tested with a PD-MFS-2MS/s-8/14 data acquisition board. After implementing reconstruction algorithms (FBP, MLEM and SART) on sinograms, images quality and system performance were evaluated by energy resolution, timing resolution, spatial resolution, scatter fraction, sensitivity, RMS contrast and SNR parameters. The energy spectra were obtained for the crystals with an energy window of 300-700 keV. The energy resolution in 511 keV averaged over all modules, detectors, and crystals, was 23.5%. A timing resolution of 2.4 ns FWHM obtained by coincidence timing spectrum was measured with crystal LYSO. The radial and tangential resolutions for 18F (1.15-mm inner diameter) at the center of the field of view were 1.81 mm and 1.90 mm, respectively. At a radial offset of 5 mm, the FWHM values were 1.96 and 2.06 mm. The system scatter fraction was 7.1% for the mouse phantom. The sensitivity was measured for different energy windows, leading to a sensitivity of 1.74% at the center of FOV. Also, images quality was evaluated by RMS contrast and SNR factors, and the results show that the reconstructed images by MLEM algorithm have the best RMS contrast, and SNR. The IRI-microPET presents high image resolution, low scatter fraction values and improved SNR for animal studies.

  9. Absolute Calibration of Si iRMs used for Si Paleo-nutrient proxies

    NASA Astrophysics Data System (ADS)

    Vocke, Robert; Rabb, Savelas

    2016-04-01

    The Avogadro Project is an ongoing international effort, coordinated by the International Bureau of Weights and Measures (BIPM) and the International Avogadro Coordination (IAC) to redefine the SI unit mole in terms of the Avogadro constant and the SI unit kg in terms of the Planck constant. One of the outgrowths of this effort has been the development of a novel, precise and highly accurate method to measure calibrated (absolute) isotopic ratios that are traceable to the SI (Vocke et al., 2014 Metrologia 51, 361, Azuma et al., 2015 Metrologia 52 360). This approach has also been able to produce absolute Si isotope ratio data with lower levels of uncertainty when compared to the traditional "Atomic Weights" method of absolute isotope ratio measurement. Silicon isotope variations (reported as delta(Si30)and delta(Si29)) in silicic acid dissolved in ocean waters, in biogenic silica and in diatoms are extremely informative paleo-nutrient proxies. The utility and comparability of such measurements however depends on calibration with artifact isotopic Reference Materials (iRMs). We will be reporting new measurements on the iRMs NBS-28 (RM 8546 - Silica Sand), Diatomite, Big Batch and SRM 990 using the Avogadro measurement approach, comparing them with prior assessments of these iRMs.

  10. A historical study to understand students’ current difficulties about RMS values

    NASA Astrophysics Data System (ADS)

    Khantine-Langlois, Françoise; Munier, Valérie

    2016-07-01

    Several studies show that students experience more and more difficulties managing the measurements of electrical values in alternating current and that they have trouble making links between theory and practice. They find it difficult to give meaning to root mean square (RMS; or effective) values, which are not understood as average values and are confused with instantaneous values. This shows that students do not clearly differentiate variable and direct currents. In this paper we try, with a historical study and a study of teaching the concept of RMS values, to understand students’ difficulties with this concept. In the first part we present an epistemological analysis of the concept of RMS values, showing that it is multifaceted and can be approached from different points of view. In the second part we analyse the evolution of French secondary school curricula and textbooks from the explicit introduction of variable currents to today, questioning the links between the evolution of the curricula and the evolution of the place of science and technology in our societies. We point out that the evolution of the curricula is linked to the social context and to the connections between science, technology and society, and also to the relationship with mathematics curricula. We show that alternating current is introduced earlier in the curriculum but has gradually lost all phenomenological description. This study allows us to better understand students’ difficulties and to discuss some implications for teaching.

  11. Erratum: Precision Velocity Fields in Spiral Galaxies. I. Noncircular Motions and rms Noise in Disks

    NASA Astrophysics Data System (ADS)

    Beauvais, Charles; Bothun, G.

    2000-05-01

    In the paper ``Precision Velocity Fields in Spiral Galaxies. I. Noncircular Motions and rms Noise in Disks'' by Charles Beauvais and G. Bothun (ApJS, 125, 99) the abstract was incorrect. The corrected abstract is as follows: Imaging Fabry-Perot data have been acquired for a sample of spiral galaxies from which two-dimensional velocity fields have been constructed on a subkiloparsec resolution scale. These velocity fields are then examined for evidence of noncircular motions. Individual spectra are extracted and the resultant line profiles are fitted with Voigt, Gaussian, and Lorentzian functions. Gaussians are shown to provide a better model for simultaneously fitting a large number of line profiles, successfully fitting a higher fraction. The kinematic disk (i.e., tilted ring) modeling procedure is studied in detail and is shown to accurately recover the underlying rotational structure of galactic disks. The process of obtaining rotation curves from full two-dimensional velocity data is examined. Small-scale ``bumps and wiggles'' on the rotation curves are shown to be due to the inclusion of noncircular motions. Use of the rotation curve estimate returned by the modeling procedure rather than deprojection of the velocity field is recommended to avoid their inclusion. Investigation of the symmetry of the major- and minor-axis rotation curves reveal strong evidence of nonconcentric gas orbits with the maximum center shift of ~300 pc. Comparisons between kinematic and photometric structure (e.g., position angles, inclinations, centers) show considerable noise on small scales. Although large-scale averages are in agreement, this noise is a matter of some concern in the application of the Tully-Fisher method to disk galaxies. Moreover, cases of significant misalignment in position angle between the inner and outer disks are seen in two of the sample galaxies and may indicate the transition between luminous and dark-matter-dominated regions (i.e., where the maximum disk

  12. On the rms anisotropy at 7 deg and 10 deg observed in the COBE-DMR two year sky maps

    NASA Technical Reports Server (NTRS)

    Banday, A. J.; Gorski, K. M.; Tenorio, L.; Wright, E. L.; Smoot, G. F.; Lineweaver, C. H.; Kogut, A.; Hinshaw, G.; Bennett, C. L.

    1994-01-01

    The frequency-independent rms temperature fluctuations determined from the Cosmic Background Explorer-Differential Microwave Radiometer (COBE-DMR) two-year sky maps are used to infer the parameter Q(sub rms-PS), which characterizes the normalization of power-law models of primordial cosmological temperature anisotropy, for a forced fit to a scale-invariant Harrison-Zel'dovich (n = 1) spectral model. Using a joint analysis of the 7 deg and 10 deg 'cross'-rms derived from both the 53 and 90 GHz sky maps, we find Q(sub rms-PS) = 17.0(sub -2.1 sup +2.5) micro Kelvin when the low quadrupole is included, and Q(sub rms-PS) = 19.4(sub -2.1 sup +2.3) micro Kelvin excluding the quadrupole. These results are consistent with the n = 1 fits from more sensitive methods. The effect of the low quadrupole derived from the COBE-DMR data on the inferred Q(sub rms-PS) normalization is investigated. A bias to lower Q(sub rms-PS) is found when the quadrupole is included. The higher normalization for a forced n = 1 fit is then favored by the cross-rms technique.

  13. Development and characterization of the CU ground MAX-DOAS instrument: lowering RMS noise and first measurements of BrO, IO, and CHOCHO near Pensacola, FL

    NASA Astrophysics Data System (ADS)

    Coburn, S.; Dix, B.; Sinreich, R.; Volkamer, R.

    2011-01-01

    We designed and assembled the University of Colorado Ground Multi AXis Differential Optical Absorption Spectroscopy (CU GMAX-DOAS) instrument to retrieve bromine oxide (BrO), iodine oxide (IO), formaldehyde (HCHO), glyoxal (CHOCHO), nitrogen dioxide (NO2) and the oxygen dimer O4 in the coastal atmosphere of the Gulf of Mexico. The detection sensitivity of DOAS measurements is directly proportional to the root mean square (RMS) of the residual spectrum that remains after all absorbers have been subtracted. Here we describe the CU GMAX-DOAS instrument and demonstrate that the hardware is capable of attaining RMS values of ~6 × 10-6 without apparent limitations other than photon shot noise. Laboratory tests revealed two factors that, in practice, limit the RMS: (1) detector non-linearity noise, RMSNLin, and (2) temperature fluctuations that cause variations in optical resolution (full width at half the maximum, FWHM, of atomic emission lines) and give rise to optical resolution noise, RMSFWHM. The non-linearity of our detector is low (~10-3) yet - unless actively controlled - is sufficiently large to create a RMSNLin limit of up to 1.4 × 10-4. The optical resolution is sensitive to temperature changes (0.03 detector pixels/°C at 334 nm), and temperature variations of 0.1 °C can cause residual RMSFWHM of ~1 × 10-4. Both factors were actively addressed in the design of the CU GMAX-DOAS instrument. The CU GMAX-DOAS was set up at a coastal site near Pensacola, FL, where we detected BrO, IO and CHOCHO in the marine boundary layer (MBL), with daytime average tropospheric vertical column densities, VCDs, of ~2 × 1013 molec cm-2, 8 × 1012 molec cm-2 and 4 × 1014 molec cm-2, respectively. HCHO and NO2 were also detected with typical MBL VCDs of 1 × 1016 and 3 × 1015. These are the first measurements of BrO, IO and CHOCHO over the Gulf of Mexico. The atmospheric implications of these observations for elevated mercury wet deposition rates in this area are briefly

  14. Effects of measurement resolution on the analysis of temperature time series for stream-aquifer flux estimation

    NASA Astrophysics Data System (ADS)

    Soto-López, Carlos D.; Meixner, Thomas; Ferré, Ty P. A.

    2011-12-01

    From its inception in the mid-1960s, the use of temperature time series (thermographs) to estimate vertical fluxes has found increasing use in the hydrologic community. Beginning in 2000, researchers have examined the impacts of measurement and parameter uncertainty on the estimates of vertical fluxes. To date, the effects of temperature measurement discretization (resolution), a characteristic of all digital temperature loggers, on the determination of vertical fluxes has not been considered. In this technical note we expand the analysis of recently published work to include the effects of temperature measurement resolution on estimates of vertical fluxes using temperature amplitude and phase shift information. We show that errors in thermal front velocity estimation introduced by discretizing thermographs differ when amplitude or phase shift data are used to estimate vertical fluxes. We also show that under similar circumstances sensor resolution limits the range over which vertical velocities are accurately reproduced more than uncertainty in temperature measurements, uncertainty in sensor separation distance, and uncertainty in the thermal diffusivity combined. These effects represent the baseline error present and thus the best-case scenario when discrete temperature measurements are used to infer vertical fluxes. The errors associated with measurement resolution can be minimized by using the highest-resolution sensors available. But thoughtful experimental design could allow users to select the most cost-effective temperature sensors to fit their measurement needs.

  15. Novel super-resolution capable mitochondrial probe, MitoRed AIE, enables assessment of real-time molecular mitochondrial dynamics

    PubMed Central

    Lo, Camden Yeung-Wah; Chen, Sijie; Creed, Sarah Jayne; Kang, Miaomiao; Zhao, Na; Tang, Ben Zhong; Elgass, Kirstin Diana

    2016-01-01

    Mitochondria and mitochondrial dynamics play vital roles in health and disease. With the intricate nanometer-scale structure and rapid dynamics of mitochondria, super-resolution microscopy techniques possess great un-tapped potential to significantly contribute to understanding mitochondrial biology and kinetics. Here we present a novel mitochondrial probe (MitoRed AIE) suitable for live mitochondrial dynamics imaging and single particle tracking (SPT), together with a multi-dimensional data analysis approach to assess local mitochondrial (membrane) fluidity. The MitoRed AIE probe localizes primarily to mitochondrial membranes, with 95 ms fluorophore on-time delivering 106 photons/ms, characteristics which we exploit to demonstrate live cell 100 fps 3D time-lapse tracking of mitochondria. Combining our experimental and analytical approaches, we uncover mitochondrial dynamics at unprecedented time scales. This approach opens up a new regime into high spatio-temporal resolution dynamics in many areas of mitochondrial biology. PMID:27492961

  16. A high-resolution time-of-flight energy analyzer for femtosecond electron pulses at 30 keV

    NASA Astrophysics Data System (ADS)

    Gliserin, Alexander; Walbran, Matthew; Baum, Peter

    2016-03-01

    We report a time-of-flight spectrometer for electron pulses at up to 30 keV, which is a suitable energy for atomic-resolution femtosecond investigations via time-resolved electron diffraction, microscopy, and energy loss spectroscopy. For realistic femtosecond beams without apertures, the instrument's energy resolution is ˜0.5 eV (full width at half maximum) or 2 × 10-5 at a throughput of 50%-90%. We demonstrate the analyzer's versatility by three first applications, namely, femtosecond electron pulse metrology via optical streaking, in situ drift correction in laser-microwave synchronization for electron pulse compression, and time-resolved electron energy loss spectroscopy of aluminum, showing the instrument's capability of tracking plasmonic loss peak positions with few-meV accuracy.

  17. HPGe detectors long time behaviour in high-resolution γ spectrometry

    NASA Astrophysics Data System (ADS)

    Sajo-Bohus, L.; Rosso, D.; Sajo Castelli, A. M.; Napoli, D. R.; Fioretto, E.; Menegazzo, R.; Barros, H.; Ur, C. A.; Palacios, D.; Liendo, J.

    2011-08-01

    A large set of data on long term performance of n-type HPGe detectors used in GASP, EUROBALL and CLARA γ spectrometers, as well as environmental measurements have been collected over two decades. In this paper a detailed statistical analysis of this data is given and detector long term behaviour is provided to the scientific community. We include failure, failure mode, repair frequency, repair outcome and its influence in the energy efficiency and energy resolution. A remarkable result is that the life span distribution is exponential. A detector's failure is a memory-less process, where a previous failure does not influence the upcoming one. Repaired spectrometers result in high reliability with deep implications in the management of large scale high-resolution gamma spectrometry related projects. Findings show that on average, detectors initial counting efficiency is slightly lower (∼2%) than that reported by the manufacturers and the repair process (including annealing) does not affect significantly the energy efficiency, even after a long period of use. Repaired detector energy resolution statistics show that the probability, that a repaired detector will be at least as good as it was originally, is more than 3/4.

  18. Time-Evolution and Thermal Mapping of Io's Loki Patera at High Resolution

    NASA Astrophysics Data System (ADS)

    de Kleer, Katherine R.; Skrutskie, Michael F.; Leisenring, Jarron; de Pater, Imke; Davies, Ashley; Conrad, Al; Caleb Resnick, Aaron; Hinz, Philip; Defrère, Denis; Veillet, Christian

    2016-10-01

    Observations of Loki Patera with Keck, Gemini N, and the Large Binocular Telescope have yielded a wealth of information in the past several years. Observations with adaptive optics at the Keck and Gemini N telescopes have captured multiple brightening events since 2009. High-cadence observations of the three most recent events place constraints on the thermal properties of the magma and indicate a dependency of the observed intensity on either viewing geometry or mean anomaly. Large Binocular Telescope Interferometer (LBTI) observations during a Europa mutual event have yielded the first-ever temperature map of the entire patera floor at high spatial resolution. M-band (4.7-micron) images were recorded during the event at a cadence of 123 milliseconds, corresponding to a spatial resolution of 10 km across the entire ~200-km patera. This represents a factor of 40 improvement over the spatial resolution achieved by standard adaptive optics imaging with a 10-m telescope at this wavelength. A map of the lava age distribution within the patera is derived from the temperature map using models for cooling basaltic lavas, and the resurfacing rate is calculated. This age distribution, as well as the locations of emission derived from the Keck and Gemini N observations, suggests that resurfacing proceeds in a clockwise direction, contrary to previous findings. All data are consistent with resurfacing by an overturn front on a magma sea, but other resurfacing mechanisms are not ruled out.

  19. Long-haul and high-resolution optical time domain reflectometry using superconducting nanowire single-photon detectors

    PubMed Central

    Zhao, Qingyuan; Xia, Lan; Wan, Chao; Hu, Junhui; Jia, Tao; Gu, Min; Zhang, Labao; Kang, Lin; Chen, Jian; Zhang, Xuping; Wu, Peiheng

    2015-01-01

    In classical optical time domain reflectometries (OTDRs), for sensing an 200-km-long fiber, the optical pulses launched are as wide as tens of microseconds to get enough signal-to-noise ratio, while it results in a two-point resolution of kilometers. To both reach long sensing distance and sub-kilometer resolution, we demonstrated a long-haul photon-counting OTDR using a superconducting nanowire single-photon detector. In a 40-minute-long measurement, we obtained a dynamic range of 46.9 dB, corresponding to a maximum sensing distance of 246.8 km, at a two-point resolution of 0.1 km. The time for measuring fiber after 100 km was reduced to one minute, while the fiber end at 217 km was still distinguished well from noise. After reducing the pulse width to 100 ns, the experimental two-point resolution was improved to 20 m while the maximum sensing distance was 209.47 km. PMID:26020163

  20. Spiral-based microfluidic device for long-term time course imaging of Neurospora crassa with single nucleus resolution.

    PubMed

    Lee, Kang Kug; Labiscsak, Laszlo; Ahn, Chong H; Hong, Christian I

    2016-09-01

    Real-time imaging of fluorescent reporters plays a critical role in elucidating fundamental molecular mechanisms including circadian rhythms in the model filamentous fungus, Neurospora crassa. However, monitoring N. crassa for an extended period of time with single nucleus resolution is a technically challenging task due to hyphal growth that rapidly moves beyond a region of interest during microscopy experiments. In this report, we have proposed a two-dimensional spiral-based microfluidic platform and applied for monitoring the single-nucleus dynamics in N. crassa for long-term time course experiments. PMID:27345439

  1. High mass resolution time of flight mass spectrometer for measuring products in heterogeneous catalysis in highly sensitive microreactors

    SciTech Connect

    Andersen, T.; Jensen, R.; Christensen, M. K.; Chorkendorff, I.; Pedersen, T.; Hansen, O.

    2012-07-15

    We demonstrate a combined microreactor and time of flight system for testing and characterization of heterogeneous catalysts with high resolution mass spectrometry and high sensitivity. Catalyst testing is performed in silicon-based microreactors which have high sensitivity and fast thermal response. Gas analysis is performed with a time of flight mass spectrometer with a modified nude Bayard-Alpert ionization gauge as gas ionization source. The mass resolution of the time of flight mass spectrometer using the ion gauge as ionization source is estimated to m/{Delta}m > 2500. The system design is superior to conventional batch and flow reactors with accompanying product detection by quadrupole mass spectrometry or gas chromatography not only due to the high sensitivity, fast temperature response, high mass resolution, and fast acquisition time of mass spectra but it also allows wide mass range (0-5000 amu in the current configuration). As a demonstration of the system performance we present data from ammonia oxidation on a Pt thin film showing resolved spectra of OH and NH{sub 3}.

  2. High mass resolution time of flight mass spectrometer for measuring products in heterogeneous catalysis in highly sensitive microreactors.

    PubMed

    Andersen, T; Jensen, R; Christensen, M K; Pedersen, T; Hansen, O; Chorkendorff, I

    2012-07-01

    We demonstrate a combined microreactor and time of flight system for testing and characterization of heterogeneous catalysts with high resolution mass spectrometry and high sensitivity. Catalyst testing is performed in silicon-based microreactors which have high sensitivity and fast thermal response. Gas analysis is performed with a time of flight mass spectrometer with a modified nude Bayard-Alpert ionization gauge as gas ionization source. The mass resolution of the time of flight mass spectrometer using the ion gauge as ionization source is estimated to m/Δm > 2500. The system design is superior to conventional batch and flow reactors with accompanying product detection by quadrupole mass spectrometry or gas chromatography not only due to the high sensitivity, fast temperature response, high mass resolution, and fast acquisition time of mass spectra but it also allows wide mass range (0-5000 amu in the current configuration). As a demonstration of the system performance we present data from ammonia oxidation on a Pt thin film showing resolved spectra of OH and NH(3).

  3. Are the yields of major cereal crops stagnating? Results from the newly developed high spatial resolution crop yield time series

    NASA Astrophysics Data System (ADS)

    Ray, D. K.; Ramankutty, N.; Foley, J. A.

    2011-12-01

    A variety of global scale studies that use crop yield time series for the last 50 years have remained constrained to using national level information due to the lack of high spatial resolution crop yield time series data. In this presentation we will unveil a new global crop yield data set for the 1961-2008 time period, at 5 min spatial resolution, and covering 174 crops. We developed this data by collecting national and sub-national harvested area and production information for individual crops. This new dataset can be used to answer questions related to global agriculture at a resolution and over a time period not previously possible. We have used this new dataset to address the question of whether the yields of the three important cereal crops -- maize, rice and wheat -- are stagnating as widely reported. Our results show that while in the older crop belts of the world yield improvements have slowed, a green revolution type of major yield increases in maize, rice and wheat are continuing in newly cultivated areas of the world.

  4. Impact of oxygen concentration on time to resolution of spontaneous pneumothorax in term infants: a population based cohort study

    PubMed Central

    2014-01-01

    Background Little evidence exists regarding the optimal concentration of oxygen to use in the treatment of term neonates with spontaneous pneumothorax (SP). The practice of using high oxygen concentrations to promote “nitrogen washout” still exists at many centers. The aim of this study was to identify the time to clinical resolution of SP in term neonates treated with high oxygen concentrations (HO: FiO2 ≥ 60%), moderate oxygen concentrations (MO: FiO2 < 60%) or room air (RA: FiO2 = 21%). Methods A population based cohort study that included all term neonates with radiologically confirmed spontaneous pneumothorax admitted to all neonatal intensive care units in Calgary, Alberta, Canada, within 72 hours of birth between 2006 and 2010. Newborns with congenital and chromosomal anomalies, meconium aspiration, respiratory distress syndrome, and transient tachypnea of newborn, pneumonia, tension pneumothorax requiring thoracocentesis or chest tube drainage or mechanical ventilation before the diagnosis of pneumothorax were excluded. The primary outcome was time to clinical resolution (hours) of SP. A Cox proportional hazards model was developed to assess differences in time to resolution of SP between treatment groups. Results Neonates were classified into three groups based on the treatment received: HO (n = 27), MO (n = 35) and RA (n = 30). There was no significant difference in time to resolution of SP between the three groups, median (range 25th-75th percentile) for HO = 12 hr (8–27), MO = 12 hr (5–24) and RA = 11 hr (4–24) (p = 0.50). A significant difference in time to resolution of SP was also not observed after adjusting for inhaled oxygen concentration [MO (a HR = 1.13, 95% CI 0.54-2.37); RA (a HR = 1.19, 95% CI 0.69-2.05)], gender (a HR = 0.87, 95% CI 0.53-1.43) and ACoRN respiratory score (a HR = 0.7, 95% CI 0.41-1.34). Conclusions Supplemental oxygen use or nitrogen washout was not

  5. High Resolution Global Climate Modeling with GEOS-5: Intense Precipitation, Convection and Tropical Cyclones on Seasonal Time-Scales.

    NASA Technical Reports Server (NTRS)

    Putnam, WilliamM.

    2011-01-01

    In 2008 the World Modeling Summit for Climate Prediction concluded that "climate modeling will need-and is ready-to move to fundamentally new high-resolution approaches to capitalize on the seamlessness of the weather-climate continuum." Following from this, experimentation with very high-resolution global climate modeling has gained enhanced priority within many modeling groups and agencies. The NASA Goddard Earth Observing System model (GEOS-5) has been enhanced to provide a capability for the execution at the finest horizontal resolutions POS,SIOle with a global climate model today. Using this high-resolution, non-hydrostatic version of GEOS-5, we have developed a unique capability to explore the intersection of weather and climate within a seamless prediction system. Week-long weather experiments, to mUltiyear climate simulations at global resolutions ranging from 3.5- to 14-km have demonstrated the predictability of extreme events including severe storms along frontal systems, extra-tropical storms, and tropical cyclones. The primary benefits of high resolution global models will likely be in the tropics, with better predictions of the genesis stages of tropical cyclones and of the internal structure of their mature stages. Using satellite data we assess the accuracy of GEOS-5 in representing extreme weather phenomena, and their interaction within the global climate on seasonal time-scales. The impacts of convective parameterization and the frequency of coupling between the moist physics and dynamics are explored in terms of precipitation intensity and the representation of deep convection. We will also describe the seasonal variability of global tropical cyclone activity within a global climate model capable of representing the most intense category 5 hurricanes.

  6. Watching entangled circular DNA in real time with super-resolution

    NASA Astrophysics Data System (ADS)

    Jee, Ah-Young; Kim, Hyeongju; Granick, Steve

    In this talk, we will show how we unraveled the conformational dynamics of entangled ring-shaped polymers in network, which is one of the most well-known problems in polymer physics, using deep imaging based on super-resolution fluorescence imaging, stimulated emission depletion (STED) microscopy. By using home-written software, we obtained the statistics of each of the hundreds of molecules, mapping out a large statistical distribution. Through inspection we not only found some aspects of the classic understanding of polymers, but some surprising aspects as well.

  7. High-resolution real-time dual-view imaging with multiple point of view microscopy

    PubMed Central

    Mangeol, Pierre; Peterman, Erwin J. G.

    2016-01-01

    Most methods to observe three-dimensional processes in living samples are based on imaging a single plane that is sequentially scanned through the sample. Sequential scanning is inherently slow, which can make it difficult to capture objects moving quickly in three dimensions. Here we present a novel method, multiple point-of-view microscopy (MPoVM), that allows simultaneous capturing of the front and side views of a sample with high resolution. MPoVM can be implemented in most fluorescence microscopes, offering new opportunities in the study of dynamic biological processes in three dimensions. PMID:27699125

  8. High-resolution real-time dual-view imaging with multiple point of view microscopy

    PubMed Central

    Mangeol, Pierre; Peterman, Erwin J. G.

    2016-01-01

    Most methods to observe three-dimensional processes in living samples are based on imaging a single plane that is sequentially scanned through the sample. Sequential scanning is inherently slow, which can make it difficult to capture objects moving quickly in three dimensions. Here we present a novel method, multiple point-of-view microscopy (MPoVM), that allows simultaneous capturing of the front and side views of a sample with high resolution. MPoVM can be implemented in most fluorescence microscopes, offering new opportunities in the study of dynamic biological processes in three dimensions.

  9. Sampling strategies and post-processing methods for increasing the time resolution of organic aerosol measurements requiring long sample-collection times

    NASA Astrophysics Data System (ADS)

    Modini, Rob L.; Takahama, Satoshi

    2016-07-01

    The composition and properties of atmospheric organic aerosols (OAs) change on timescales of minutes to hours. However, some important OA characterization techniques typically require greater than a few hours of sample-collection time (e.g., Fourier transform infrared (FTIR) spectroscopy). In this study we have performed numerical modeling to investigate and compare sample-collection strategies and post-processing methods for increasing the time resolution of OA measurements requiring long sample-collection times. Specifically, we modeled the measurement of hydrocarbon-like OA (HOA) and oxygenated OA (OOA) concentrations at a polluted urban site in Mexico City, and investigated how to construct hourly resolved time series from samples collected for 4, 6, and 8 h. We modeled two sampling strategies - sequential and staggered sampling - and a range of post-processing methods including interpolation and deconvolution. The results indicated that relative to the more sophisticated and costly staggered sampling methods, linear interpolation between sequential measurements is a surprisingly effective method for increasing time resolution. Additional error can be added to a time series constructed in this manner if a suboptimal sequential sampling schedule is chosen. Staggering measurements is one way to avoid this effect. There is little to be gained from deconvolving staggered measurements, except at very low values of random measurement error (< 5 %). Assuming 20 % random measurement error, one can expect average recovery errors of 1.33-2.81 µg m-3 when using 4-8 h-long sequential and staggered samples to measure time series of concentration values ranging from 0.13-29.16 µg m-3. For 4 h samples, 19-47 % of this total error can be attributed to the process of increasing time resolution alone, depending on the method used, meaning that measurement precision would only be improved by 0.30-0.75 µg m-3 if samples could be collected over 1 h instead of 4 h. Devising a

  10. STS-37 Gamma Ray Observatory (GRO) held by RMS over OV-104's payload bay

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The Gamma Ray Observatory (GRO) with its solar array (SA) panels deployed is grappled by the remote manipulator system (RMS) and held over Atlantis', Orbiter Vehicle (OV) 104's, payload bay (PLB) during systems checkout. GRO's four complement instruments are visible: the Energetic Gamma Ray Experiment Telescope (EGRET) (at the bottom); the Imaging Compton Telescope (COMPTEL) (center); the Oriented Scintillation Spectrometer Experiment (OSSE) (top); and Burst and Transient Source Experiment (BATSE) (on four corners). This view taken by the STS-37 crew shows the GRO backdropped against clouds over water on the Earth's surface.

  11. During STS-32 retrieval, RMS lowers LDEF into OV-102's payload bay (PLB)

    NASA Technical Reports Server (NTRS)

    1990-01-01

    During STS-32 retrieval activities, the Long Duration Exposure Facility (LDEF) grappled by the remote manipulator system (RMS) end effector is lowered into Columbia's, Orbiter Vehicle (OV) 102's, lit payload bay (PLB). The scene is framed in an aft flight deck viewing window. Visible on the 14 ft (4.3 meter) end of LDEF is the support structure with payload retention latch assembly (PRLA) trunnions that will secure the reusable 12-sided structure in the PLB during reentry and landing. In the background, highlighted against the Earth's surface are OV-102's wings, the orbital maneuvering system (OMS) pods, and the vertical tail.

  12. LDEF grappled and positioned by RMS over OV-102's payload bay during STS-32

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The Long Duration Exposure Facility (LDEF) is grappled by remote manipulator system (RMS) end effector and positioned horizontally over Columbia's, Orbiter Vehicle (OV) 102's, payload bay (PLB) during STS-32 retrieval activities. LDEF is a free-flying passive spacecraft that has provided 57 experiments with long-term exposure to the space environment. The gradient stabilized platform was deployed in April, 1984. Also visible are the PLB, the frame of an aft viewing window, the orbital maneuvering system (OMS) pods and vertical tail, and the cloud-covered Earth surface.

  13. STS-39 SPAS-II/IBSS spacecraft is released by RMS above the Earth's surface

    NASA Technical Reports Server (NTRS)

    1991-01-01

    During STS-39 mission operations, the Shuttle Pallet Satellite II (SPAS-II) / Infrared Background Signature Survey (IBSS) spacecraft is released by Discovery's, Orbiter Vehicle (OV) 103's, remote manipulator system (RMS) end effector. SPAS-II/IBSS drifts away from the end effector over the cloud-covered surface of the Earth. Components visible on the spacecraft include the grapple fixture, the longeron trunnion, scuff plate, cryostat, and Arizona Imager/Spectrograph (AIS) (in shadows). SPAS-II is a Strategic Defense Initiative Organization (SDIO) payload.

  14. OV-104's RMS grapples EURECA-1L and holds it in deployment position above PLB

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The European Retrievable Carrier 1L (EURECA-1L), grappled by the remote manipulator system (RMS) end effector, is positioned over the payload bay (PLB) of Atlantis, Orbiter Vehicle (OV) 104, prior to deployment. EURECA-1L's solar array panels are deployed. Below EURECA-1L, in the PLB, is the Tethered Satellite System 1 (TSS-1) with the TSS-1 satellite stowed in the satellite support assembly (SSA) mounted on a unpressurized spacelab (SL) pallet. The vertical tail and the orbital maneuvering system (OMS) pods are visible. The entire scene is backdropped by a land mass and ocean on the Earth's surface below.

  15. STS-39 SPAS-II/IBSS spacecraft is released by RMS above the Earth's surface

    NASA Technical Reports Server (NTRS)

    1991-01-01

    During STS-39 mission operations, the Shuttle Pallet Satellite II (SPAS-II) / Infrared Background Signature Survey (IBSS) spacecraft is released by Discovery's, Orbiter Vehicle (OV) 103's, remote manipulator system (RMS) end effector. SPAS-II/IBSS drifts away from the end effector over the cloud-covered surface of the Earth highlighted by a sun glint. Components visible on the spacecraft include the grapple fixture, the longeron trunnion, scuff plate, cryostat, and keel trunnion with radar enhancement devices (spheres). SPAS-II is a Strategic Defense Initiative Organization (SDIO) payload.

  16. STS-39 SPAS-II IBSS is grappled by remote manipulator system (RMS)

    NASA Technical Reports Server (NTRS)

    1991-01-01

    STS-39 Shuttle Pallet Satellite II (SPAS-II) / Infrared Background Signature Survey (IBSS) spacecraft is grappled by remote manipulator system (RMS) end effector. Backdropped against the cloud-covered surface of the Earth, SPAS-II/IBSS spacecraft is extended outside Discovery's, Orbiter Vehicle (OV) 103's, payload bay (PLB). Components visible on the SPAS-II/IBSS spacecraft include the Cryostat, antennas, NFOV TV camera, WFOV TV camera, Arizona Imager/Spectrograph (AIS), and the handling trunnions. SPAS-II is a Strategic Defense Initiative Organization (SDIO) payload.

  17. STS-31 Hubble Space Telescope (HST) is released by RMS over Andes Mountains

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The Hubble Space Telescope (HST), with solar array (SA) wings and high gain antennae (HGA) masts fully extended, is released by the remote manipulator system (RMS) end effector. The STS-31 crew aboard Discovery, Orbiter Vehicle (OV) 103, set the HST into Earth orbit high above the Andes Mountains. Parts of Bolivia, Peru, Chile, and Argentina are visible. This picture covers a huge area of the western half of South America stretching from 14 degrees south latitude to 23 degrees, about 1,000 kilometers.

  18. STS-31 Hubble Space Telescope (HST) drifts away from OV-103's RMS

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Hubble Space Telescope (HST), with its solar array (SA) wings and high gain antennae (HGA) fully extended,is released from Discovery's, Orbiter Vehicle (OV) 103's, remote manipulator system (RMS) end effector and is set free into Earth orbit by the STS-31 crew. HST drifts away from the end effector over the Andes Mountains.Parts of Bolivia, Peru, Chile, and Argentina are visible. The view covers a huge area of the western half of South America stretching from 14 degrees south latitude to 23 degrees, about 1,000 kilometers.

  19. Real-time MRI of speaking at a resolution of 33 ms: undersampled radial FLASH with nonlinear inverse reconstruction.

    PubMed

    Niebergall, Aaron; Zhang, Shuo; Kunay, Esther; Keydana, Götz; Job, Michael; Uecker, Martin; Frahm, Jens

    2013-02-01

    Dynamic MRI studies of the upper airway during speaking, singing or swallowing are complicated by the need for high temporal resolution and the presence of air-tissue interfaces that may give rise to image artifacts such as signal void and geometric distortions. This work exploits a recently developed real-time MRI technique to address these challenges for monitoring speech production at 3 T. The method combines a short-echo time radial FLASH MRI sequence (pulse repetition time/echo time = 2.22/1.44 ms; flip angle 5°) with pronounced undersampling (15 radial spokes per image) and image reconstruction by regularized nonlinear inversion. The resulting serial images at 1.5 mm in-plane resolution and 33.3 ms acquisition time are free of motion or susceptibility artifacts. This application focuses on a dynamic visualization of the main articulators during natural speech production (Standard Modern German). Respective real-time MRI movies at 30 frames per second clearly demonstrate the spatiotemporal coordination of lips, tongue, velum, and larynx for generating vowels, consonants, and coarticulations. The quantitative results for individual phonetic events are in agreement with previous non-MRI findings. PMID:22498911

  20. Cost-effective approaches for high-resolution bioimaging by time-stretched confocal microscopy at 1μm

    NASA Astrophysics Data System (ADS)

    Wong, Terence T. W.; Qiu, Yi; Lau, Andy K. S.; Xu, JingJiang; Chan, Antony C. S.; Wong, Kenneth K. Y.; Tsia, Kevin K.

    2012-12-01

    Optical imaging based on time-stretch process has recently been proven as a powerful tool for delivering ultra-high frame rate (< 1MHz) which is not achievable by the conventional image sensors. Together with the capability of optical image amplification for overcoming the trade-off between detection sensitivity and speed, this new imaging modality is particularly valuable in high-throughput biomedical diagnostic practice, e.g. imaging flow cytometry. The ultra-high frame rate in time-stretch imaging is attained by two key enabling elements: dispersive fiber providing the time-stretch process via group-velocity-dispersion (GVD), and electronic digitizer. It is well-known that many biophotonic applications favor the spectral window of ~1μm. However, reasonably high GVD (< 0.1 ns/nm) in this range can only be achieved by using specialty single-mode fiber (SMF) at 1μm. Moreover, the ultrafast detection has to rely on the state-of- the-art digitizer with significantly wide-bandwidth and high sampling rate (e.g. <10 GHz, <40 GS/s). These stringent requirements imply the prohibitively high-cost of the system and hinder its practical use in biomedical diagnostics. We here demonstrate two cost-effective approaches for realizing time-stretch confocal microscopy at 1μm: (i) using the standard telecommunication SMF (e.g. SMF28) to act as a few-mode fiber (FMF) at 1μm for the time-stretch process, and (ii) implementing the pixel super-resolution (SR) algorithm to restore the high-resolution (HR) image when using a lower-bandwidth digitizer. By using a FMF (with a GVD of ~ 0.15ns/nm) and a modified pixel-SR algorithm, we can achieve time-stretch confocal microscopy at 1μm with cellular resolution (~ 3μm) at a frame rate 1 MHz.

  1. Note: Design of a full photon-timing recorder down to 1-ns resolution for fluorescence fluctuation measurements

    SciTech Connect

    Nishimura, Goro

    2015-10-15

    A photon timing recorder was realized in a field programmable gate array to capture all timing data of photons on multiple channels with down to a 1-ns resolution and to transfer all data to a host computer in real-time through universal serial bus with more than 10 M events/s transfer rate. The main concept is that photon time series can be regarded as a serial communication data stream. This recorder was successfully applied for simultaneous measurements of fluorescence fluctuation and lifetime of near-infrared dyes in solution. This design is not only limited to the fluorescence fluctuation measurement but also applicable to any kind of photon counting experiments in a nanosecond time range because of the simple and easily modifiable design.

  2. Note: Design of a full photon-timing recorder down to 1-ns resolution for fluorescence fluctuation measurements

    NASA Astrophysics Data System (ADS)

    Nishimura, Goro

    2015-10-01

    A photon timing recorder was realized in a field programmable gate array to capture all timing data of photons on multiple channels with down to a 1-ns resolution and to transfer all data to a host computer in real-time through universal serial bus with more than 10 M events/s transfer rate. The main concept is that photon time series can be regarded as a serial communication data stream. This recorder was successfully applied for simultaneous measurements of fluorescence fluctuation and lifetime of near-infrared dyes in solution. This design is not only limited to the fluorescence fluctuation measurement but also applicable to any kind of photon counting experiments in a nanosecond time range because of the simple and easily modifiable design.

  3. X-ray bang-time and fusion reaction history at ~ps resolution using RadOptic detection

    SciTech Connect

    Vernon, S P; Lowry, M E; Baker, K L; Bennett, C V; Celeste, J R; Cerjan, C; Haynes, S; Hernandez, V J; Hsing, W W; London, R A; Moran, B; von Wittenau, A S; Steele, P T; Stewart, R E

    2012-05-01

    We report recent progress in the development of RadOptic detectors, radiation to optical converters, that rely upon x-ray absorption induced modulation of the optical refractive index of a semiconductor sensor medium to amplitude modulate an optical probe beam. The sensor temporal response is determined by the dynamics of the electron-hole pair creation and subsequent relaxation in the sensor medium. Response times of a few ps have been demonstrated in a series of experiments conducted at the LLNL Jupiter Laser Facility. This technology will enable x-ray bang-time and fusion burn-history measurements with {approx} ps resolution.

  4. X-ray bang-time and fusion reaction history at picosecond resolution using RadOptic detection

    SciTech Connect

    Vernon, S. P.; Lowry, M. E.; Baker, K. L.; Bennett, C. V.; Celeste, J. R.; Cerjan, C.; Haynes, S.; Hernandez, V. J.; Hsing, W. W.; LaCaille, G. A.; London, R. A.; Moran, B.; Schach von Wittenau, A.; Steele, P. T.; Stewart, R. E.

    2012-10-15

    We report recent progress in the development of RadOptic detectors, radiation to optical converters, that rely upon x-ray absorption induced modulation of the optical refractive index of a semiconductor sensor medium to amplitude modulate an optical probe beam. The sensor temporal response is determined by the dynamics of the electron-hole pair creation and subsequent relaxation in the sensor medium. Response times of a few ps have been demonstrated in a series of experiments conducted at the LLNL Jupiter Laser Facility (JLF). This technology will enable x-ray bang-time and fusion burn-history measurements with {approx} ps resolution.

  5. A rapid reflectance-difference spectrometer for real-time semiconductor growth monitoring with sub-second time resolution.

    PubMed

    Núñez-Olvera, O; Balderas-Navarro, R E; Ortega-Gallegos, J; Guevara-Macías, L E; Armenta-Franco, A; Lastras-Montaño, M A; Lastras-Martínez, L F; Lastras-Martínez, A

    2012-10-01

    We report on a rapid, 32-channel reflectance-difference (RD) spectrometer with sub-second spectra acquisition times and ΔR/R sensitivity in the upper 10(-4) range. The spectrometer is based on a 50 kHz photo-elastic modulator for light polarization modulation and on a lock-in amplifier for signal harmonic analysis. Multichannel operation is allowed by multiplexing the 32 outputs of the spectrometer into the input of the lock-in amplifier. The spectrometer spans a wavelength range of 230 nm that can be tuned to cover E(1) and E(1) + Δ(1) transitions for a number of III-V semiconductors at epitaxial growth temperatures, including GaAs, InAs, AlAs, and their alloys. We present two examples of real-time measurements to demonstrate the performance of the RD spectrometer, namely, the evolution of the RD spectrum of GaAs (001) annealed at 500 °C and the time-dependent RD spectrum during the first stages of the epitaxial growth of In(0.3)Ga(0.7)As on GaAs (001) substrates.

  6. Quantifying the effect of temporal resolution on time-varying networks

    PubMed Central

    Ribeiro, Bruno; Perra, Nicola; Baronchelli, Andrea

    2013-01-01

    Time-varying networks describe a wide array of systems whose constituents and interactions evolve over time. They are defined by an ordered stream of interactions between nodes, yet they are often represented in terms of a sequence of static networks, each aggregating all edges and nodes present in a time interval of size Δt. In this work we quantify the impact of an arbitrary Δt on the description of a dynamical process taking place upon a time-varying network. We focus on the elementary random walk, and put forth a simple mathematical framework that well describes the behavior observed on real datasets. The analytical description of the bias introduced by time integrating techniques represents a step forward in the correct characterization of dynamical processes on time-varying graphs. PMID:24141695

  7. Towards a microchannel-based X-ray detector with two-dimensional spatial and time resolution and high dynamic range

    SciTech Connect

    Adams, Bernhard W.; Mane, Anil; Elam, Jeffrey; Obaid, Razib; Wetstein, Matthew J.

    2015-09-01

    X-ray detectors that combine two-dimensional spatial resolution with a high time resolution are needed in numerous applications of synchrotron radiation. Most detectors with this combination of capabilities are based on semiconductor technology and are therefore limited in size. Furthermore, the time resolution is often realised through rapid time-gating of the acquisition, followed by a slower readout. Here, a detector technology is realised based on relatively inexpensive microchannel plates that uses GHz waveform sampling for a millimeter-scale spatial resolution and better than 100 ps time resolution. The technology is capable of continuous streaming of time- and location-tagged events at rates greater than 10(7) events per cm(2). Time-gating can be used for improved dynamic range.

  8. Real-time high-resolution downsampling algorithm on many-core processor for spatially scalable video coding

    NASA Astrophysics Data System (ADS)

    Buhari, Adamu Muhammad; Ling, Huo-Chong; Baskaran, Vishnu Monn; Wong, KokSheik

    2015-01-01

    The progression toward spatially scalable video coding (SVC) solutions for ubiquitous endpoint systems introduces challenges to sustain real-time frame rates in downsampling high-resolution videos into multiple layers. In addressing these challenges, we put forward a hardware accelerated downsampling algorithm on a parallel computing platform. First, we investigate the principal architecture of a serial downsampling algorithm in the Joint-Scalable-Video-Model reference software to identify the performance limitations for spatially SVC. Then, a parallel multicore-based downsampling algorithm is studied as a benchmark. Experimental results for this algorithm using an 8-core processor exhibit performance speedup of 5.25× against the serial algorithm in downsampling a quantum extended graphics array at 1536p video resolution into three lower resolution layers (i.e., Full-HD at 1080p, HD at 720p, and Quarter-HD at 540p). However, the achieved speedup here does not translate into the minimum required frame rate of 15 frames per second (fps) for real-time video processing. To improve the speedup, a many-core based downsampling algorithm using the compute unified device architecture parallel computing platform is proposed. The proposed algorithm increases the performance speedup to 26.14× against the serial algorithm. Crucially, the proposed algorithm exceeds the target frame rate of 15 fps, which in turn is advantageous to the overall performance of the video encoding process.

  9. Reconstruction of multiple ELVES with high time resolution and longer trace length at the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Mussa, R.; Tonachini, A. S.

    2014-12-01

    The Pierre Auger Observatory, located in Malargue (Argentina), is the largest facility (3000 km2 ) for the study of Ultra High Energy Cosmic Rays (E>1018 eV). The four sites of the Fluorescence Detector (covering a field of view of 30x180 degrees each) are continuously observing the night sky with 100 ns time resolution and a space resolution below one degree. Since March 2013, a special trigger has been implemented to detect ELVES candidates with high efficiency, and since January 2014 the ELVES candidates are read with a modified DAQ scheme, which allowed to extend the trace lengths from 100 to 300 microseconds. This dedicated upgrade allows to observe the light emission from above the vertical of the causative lightning and to harvest a large sample of ELVES showing a double or even triple peak structure. In addition, a comprehensive review of the detector performance (trigger efficiency, time and angular resolution, altitude of the emission layer) during the data taking periods 2013 and 2014 is given.

  10. Resolution limitations from detector pulse width and jitter in a linear orthogonal-acceleration time-of-flight mass spectrometer.

    PubMed

    Coles, J N; Guilhaus, M

    1994-08-01

    Recent and ongoing advances in timing electronics together with the development of ionization techniques suited to time-of-flight mass spectrometry (TOF-MS) have contributed to renewed interest in this method of mass analysis. Whereas low resolving powers (m/†m < 500) were once an almost unavoidable drawback in TOF-MS, recent developments in instrument geometries have produced much higher resolving powers for many ion sources. The temporal width of detector pulses and jitter in timing electronics, however, lead to contributions to peak widths that are essentially independent of the mass-analyzer ion optics. The effective detector pulse width (†t d ≈ 1-10 ns typically) can be a limiting factor in the development of high resolution time-of-flight (TOF) instruments with modest drift lengths (∼1 m), It also reduces the mass resolution more seriously for light ions. This article presents a method for distinguishing the instrumental "ion arrival-time" resolution (R o) of a linear TOF mass analyzer from that which is locally measured at a particular mass, limited by the broadening of the detector pulse width and electronics. The method also provides an estimate of †t d, that is useful in determining the temporal performance of the detection system. The model developed here is tested with data from a recently constructed orthogonal-acceleration TOF mass spectrometer equipped with a commercially available transient recorder (a LeCroy 400-Msamplejs digital oscilloscope) from which we obtained R o = 4240 ± 100 [full width at half maximum (FWHM)) and †t d = 3.0 ± 0.1 ns (FWHM).

  11. Results from the NA62 Gigatracker Prototype: A Low-Mass and sub-ns Time Resolution Silicon Pixel Detector

    NASA Astrophysics Data System (ADS)

    Fiorini, M.; Rinella, G. Aglieri; Carassiti, V.; Ceccucci, A.; Gil, E. Cortina; Ramusino, A. Cotta; Dellacasa, G.; Garbolino, S.; Jarron, P.; Kaplon, J.; Kluge, A.; Marchetto, F.; Mapelli, A.; Martin, E.; Mazza, G.; Morel, M.; Noy, M.; Nuessle, G.; Petagna, P.; Petrucci, F.; Perktold, L.; Riedler, P.; Rivetti, A.; Statera, M.; Velghe, B.

    The Gigatracker (GTK) is a hybrid silicon pixel detector developed for NA62, the experiment aimed at studying ultra-rare kaon decays at the CERN SPS. Three GTK stations will provide precise momentum and angular measurements on every track of the high intensity NA62 hadron beam with a time-tagging resolution of 150 ps. Multiple scattering and hadronic interactions of beam particles in the GTK have to be minimized to keep background events at acceptable levels, hence the total material budget is fixed to 0.5% X0 per station. In addition the calculated fluence for 100 days of running is 2×1014 1 MeV neq/cm2, comparable to the one expected for the inner trackers of LHC detectors in 10 years of operation. These requirements pose challenges for the development of an efficient and low-mass cooling system, to be operated in vacuum, and on the thinning of read-out chips to 100 μm or less. The most challenging requirement is represented by the time resolution, which can be achieved by carefully compensating for the discriminator time-walk. For this purpose, two complementary read-out architectures have been designed and produced as small-scale prototypes: the first is based on the use of a Time-over-Threshold circuit followed by a TDC shared by a group of pixels, while the other uses a constant-fraction discriminator followed by an on-pixel TDC. The readout pixel ASICs are produced in 130 nm IBM CMOS technology and bump-bonded to 200 μm thick silicon sensors. The Gigatracker detector system is described with particular emphasis on recent experimental results obtained from laboratory and beam tests of prototype bump-bonded assemblies, which show a time resolution of less than 200 ps for single hits.

  12. Benchmarking of measurement and simulation of transverse rms-emittance growth

    NASA Astrophysics Data System (ADS)

    Groening, L.; Barth, W.; Bayer, W.; Clemente, G.; Dahl, L.; Forck, P.; Gerhard, P.; Hofmann, I.; Riehl, G.; Yaramyshev, S.; Jeon, D.; Uriot, D.

    2008-09-01

    Transverse emittance growth along the Alvarez drift tube linac (DTL) section is a major concern with respect to the preservation of beam quality of high current beams at the GSI UNILAC. In order to define measures to reduce this growth, appropriate tools to simulate the beam dynamics are indispensable. This paper is about the benchmarking of three beam dynamics simulation codes, i.e. DYNAMION, PARMILA, and PARTRAN against systematic measurements of beam emittances for different transverse phase advances along the DTL. Special emphasis is put on the modeling of the initial distribution for the simulations. The concept of rms equivalence is expanded from full intensity to fractions of less than 100% of the beam. The experimental setup, data reduction, preparation of the simulations, and the evaluation of the simulations are described. In the experiments and in the simulations, a minimum of the rms-emittance growth was observed at zero current phase advances of about 60°. In general, good agreement was found between simulations and experiment for the mean values of horizontal and vertical emittances at the DTL exit.

  13. Sensitivity of power and RMS delay spread predictions of a 3D indoor ray tracing model.

    PubMed

    Liu, Zhong-Yu; Guo, Li-Xin; Li, Chang-Long; Wang, Qiang; Zhao, Zhen-Wei

    2016-06-13

    This study investigates the sensitivity of a three-dimensional (3D) indoor ray tracing (RT) model for the use of the uniform theory of diffraction and geometrical optics in radio channel characterizations of indoor environments. Under complex indoor environments, RT-based predictions require detailed and accurate databases of indoor object layouts and the electrical characteristics of such environments. The aim of this study is to assist in selecting the appropriate level of accuracy required in indoor databases to achieve good trade-offs between database costs and prediction accuracy. This study focuses on the effects of errors in indoor environments on prediction results. In studying the effects of inaccuracies in geometry information (indoor object layout) on power coverage prediction, two types of artificial erroneous indoor maps are used. Moreover, a systematic analysis is performed by comparing the predictions with erroneous indoor maps and those with the original indoor map. Subsequently, the influence of random errors on RMS delay spread results is investigated. Given the effect of electrical parameters on the accuracy of the predicted results of the 3D RT model, the relative permittivity and conductivity of different fractions of an indoor environment are set with different values. Five types of computer simulations are considered, and for each type, the received power and RMS delay spread under the same circumstances are simulated with the RT model.

  14. Sensitivity of power and RMS delay spread predictions of a 3D indoor ray tracing model.

    PubMed

    Liu, Zhong-Yu; Guo, Li-Xin; Li, Chang-Long; Wang, Qiang; Zhao, Zhen-Wei

    2016-06-13

    This study investigates the sensitivity of a three-dimensional (3D) indoor ray tracing (RT) model for the use of the uniform theory of diffraction and geometrical optics in radio channel characterizations of indoor environments. Under complex indoor environments, RT-based predictions require detailed and accurate databases of indoor object layouts and the electrical characteristics of such environments. The aim of this study is to assist in selecting the appropriate level of accuracy required in indoor databases to achieve good trade-offs between database costs and prediction accuracy. This study focuses on the effects of errors in indoor environments on prediction results. In studying the effects of inaccuracies in geometry information (indoor object layout) on power coverage prediction, two types of artificial erroneous indoor maps are used. Moreover, a systematic analysis is performed by comparing the predictions with erroneous indoor maps and those with the original indoor map. Subsequently, the influence of random errors on RMS delay spread results is investigated. Given the effect of electrical parameters on the accuracy of the predicted results of the 3D RT model, the relative permittivity and conductivity of different fractions of an indoor environment are set with different values. Five types of computer simulations are considered, and for each type, the received power and RMS delay spread under the same circumstances are simulated with the RT model. PMID:27410335

  15. Tuning the instrument resolution using chopper and time of flight at the small-angle neutron scattering diffractometer KWS-2

    PubMed Central

    Radulescu, Aurel; Székely, Noémi Kinga; Polachowski, Stephan; Leyendecker, Marko; Amann, Matthias; Buitenhuis, Johan; Drochner, Matthias; Engels, Ralf; Hanslik, Romuald; Kemmerling, Günter; Lindner, Peter; Papagiannopoulos, Aristeidis; Pipich, Vitaliy; Willner, Lutz; Frielinghaus, Henrich; Richter, Dieter

    2015-01-01

    Following demand from the user community regarding the possibility of improving the experimental resolution, the dedicated high-intensity/extended Q-range SANS diffractometer KWS-2 of the Jülich Centre for Neutron Science at the Heinz Maier-Leibnitz Center in Garching was equipped with a double-disc chopper with a variable opening slit window and time-of-flight (TOF) data acquisition option. The chopper used in concert with a dedicated high-intensity velocity selector enables the tuning at will of the wavelength resolution Δλ/λ within a broad range, from 20% (standard) down to 2%, in a convenient and safe manner following pre-planned or spontaneous decisions during the experiment. The new working mode is described in detail, and its efficiency is demonstrated on several standard samples with known properties and on a completely new crystallizable copolymer system, which were investigated using both the conventional (static) and TOF modes. PMID:26664343

  16. Time-to-digital converter card for multichannel time-resolved single-photon counting applications

    NASA Astrophysics Data System (ADS)

    Tamborini, Davide; Portaluppi, Davide; Tisa, Simone; Tosi, Alberto

    2015-03-01

    We present a high performance Time-to-Digital Converter (TDC) card that provides 10 ps timing resolution and 20 ps (rms) timing precision with a programmable full-scale-range from 160 ns to 10 μs. Differential Non-Linearity (DNL) is better than 1.3% LSB (rms) and Integral Non-Linearity (INL) is 5 ps rms. Thanks to the low power consumption (400 mW) and the compact size (78 mm x 28 mm x 10 mm), this card is the building block for developing compact multichannel time-resolved instrumentation for Time-Correlated Single-Photon Counting (TCSPC). The TDC-card outputs the time measurement results together with the rates of START and STOP signals and the number of valid TDC conversions. These additional information are needed by many TCSPC-based applications, such as: Fluorescence Lifetime Imaging (FLIM), Time-of-Flight (TOF) ranging measurements, time-resolved Positron Emission Tomography (PET), single-molecule spectroscopy, Fluorescence Correlation Spectroscopy (FCS), Diffuse Optical Tomography (DOT), Optical Time-Domain Reflectometry (OTDR), quantum optics, etc.

  17. Integration of the Shuttle RMS/CBM Positioning Virtual Environment Simulation

    NASA Technical Reports Server (NTRS)

    Dumas, Joseph D.

    1996-01-01

    Constructing the International Space Station, or other structures, in space presents a number of problems. In particular, payload restrictions for the Space Shuttle and other launch mechanisms prohibit assembly of large space-based structures on Earth. Instead, a number of smaller modules must be boosted into orbit separately and then assembled to form the final structure. The assembly process is difficult, as docking interfaces such as Common Berthing Mechanisms (CBMS) must be precisely positioned relative to each other to be within the "capture envelope" (approximately +/- 1 inch and +/- 0.3 degrees from the nominal position) and attach properly. In the case of the Space Station, the docking mechanisms are to be positioned robotically by an astronaut using the 55-foot-long Remote Manipulator System (RMS) robot arm. Unfortunately, direct visual or video observation of the placement process is difficult or impossible in many scenarios. One method that has been tested for aligning the CBMs uses a boresighted camera mounted on one CBM to view a standard target on the opposing CBM. While this method might be sufficient to achieve proper positioning with considerable effort, it does not provide a high level of confidence that the mechanisms have been placed within capture range of each other. It also does nothing to address the risk of inadvertent contact between the CBMS, which could result in RMS control software errors. In general, constraining the operator to a single viewpoint with few, if any, depth cues makes the task much more difficult than it would be if the target could be viewed in three-dimensional space from various viewpoints. The actual work area could be viewed by an astronaut during EVA; however, it would be extremely impractical to have an astronaut control the RMS while spacewalking. On the other hand, a view of the RMS and CBMs to be positioned in a virtual environment aboard the Space Shuttle orbiter or Space Station could provide similar benefits

  18. Nanoalloying in real time. A high resolution STEM and computer simulation study

    NASA Astrophysics Data System (ADS)

    Mariscal, M. M.; Mayoral, A.; Olmos-Asar, J. A.; Magen, C.; Mejía-Rosales, S.; Pérez-Tijerina, E.; José-Yacamán, M.

    2011-12-01

    Bimetallic nanoparticles constitute a promising type of catalysts, mainly because their physical and chemical properties may be tuned by varying their chemical composition, atomic ordering, and size. Today, the design of novel nanocatalysts is possible through a combination of virtual lab simulations on massive parallel computing and modern electron microscopy with picometre resolution on one hand, and the capability of chemical analysis at the atomic scale on the other. In this work we show how the combination of theoretical calculations and characterization can solve some of the paradoxes reported about nanocatalysts: Au-Pd bimetallic nanoparticles. In particular, we demonstrate the key role played by adsorbates, such as carbon monoxide (CO), on the structure of nanoalloys. Our results imply that surface condition of nanoparticles during synthesis is a parameter of paramount importance.Bimetallic nanoparticles constitute a promising type of catalysts, mainly because their physical and chemical properties may be tuned by varying their chemical composition, atomic ordering, and size. Today, the design of novel nanocatalysts is possible through a combination of virtual lab simulations on massive parallel computing and modern electron microscopy with picometre resolution on one hand, and the capability of chemical analysis at the atomic scale on the other. In this work we show how the combination of theoretical calculations and characterization can solve some of the paradoxes reported about nanocatalysts: Au-Pd bimetallic nanoparticles. In particular, we demonstrate the key role played by adsorbates, such as carbon monoxide (CO), on the structure of nanoalloys. Our results imply that surface condition of nanoparticles during synthesis is a parameter of paramount importance. Electronic supplementary information (ESI) available: (S1) (a) Aberration corrected STEM-HAADF image taken after beam irradiation, where the intensity profile, marked by a red rectangle, was taken

  19. Toward observationally constrained high space and time resolution CO2 urban emission inventories

    NASA Astrophysics Data System (ADS)

    Maness, H.; Teige, V. E.; Wooldridge, P. J.; Weichsel, K.; Holstius, D.; Hooker, A.; Fung, I. Y.; Cohen, R. C.

    2013-12-01

    The spatial patterns of greenhouse gas (GHG) emission and sequestration are currently studied primarily by sensor networks and modeling tools that were designed for global and continental scale investigations of sources and sinks. In urban contexts, by design, there has been very limited investment in observing infrastructure, making it difficult to demonstrate that we have an accurate understanding of the mechanism of emissions or the ability to track processes causing changes in those emissions. Over the last few years, our team has built a new high-resolution observing instrument to address urban CO2 emissions, the BErkeley Atmospheric CO2 Observing Network (BEACON). The 20-node network is constructed on a roughly 2 km grid, permitting direct characterization of the internal structure of emissions within the San Francisco East Bay. Here we present a first assessment of BEACON's promise for evaluating the effectiveness of current and upcoming local emissions policy. Within the next several years, a variety of locally important changes are anticipated--including widespread electrification of the motor vehicle fleet and implementation of a new power standard for ships at the port of Oakland. We describe BEACON's expected performance for detecting these changes, based on results from regional forward modeling driven by a suite of projected inventories. We will further describe the network's current change detection capabilities by focusing on known high temporal frequency changes that have already occurred; examples include a week of significant freeway traffic congestion following the temporary shutdown of the local commuter rail (the Bay Area Rapid Transit system).

  20. High-resolution micromechanical measurement in real time of forces exerted by living cells

    PubMed Central

    Swierczewski, Robert; Hedley, John; Redfern, Chris P. F.

    2016-01-01

    ABSTRACT The aim of this study was to compare uniaxial traction forces exerted by different cell types using a novel sensor design and to test the dependence of measured forces on cytoskeletal integrity. The sensor design detects forces generated between 2 contact points by cells spanning a gap. The magnitude of these forces varied according to cell type and were dependent on cytoskeletal integrity. The response time for drug-induced cytoskeletal disruption also varied between cell types: dermal fibroblasts exerted the greatest forces and had the slowest drug response times; EBV-transformed epithelial cells also had slow cytoskeletal depolymerisation times but exerted the lowest forces overall. Conversely, lung epithelial tumor cells exerted low forces but had the fastest depolymerisation drug response. These results provide proof of principle for a new design of force-measurement sensor based on optical interferometry, an approach that can be used to study cytoskeletal dynamics in real time. PMID:26645140

  1. High-Speed, High-Resolution Time-to-Digital Conversion

    NASA Technical Reports Server (NTRS)

    Katz, Richard; Kleyner, Igor; Garcia, Rafael

    2013-01-01

    This innovation is a series of time-tag pulses from a photomultiplier tube, featuring short time interval between pulses (e.g., 2.5 ns). Using the previous art, dead time between pulses is too long, or too much hardware is required, including a very-high-speed demultiplexer. A faster method is needed. The goal of this work is to provide circuits to time-tag pulses that arrive at a high rate using the hardwired logic in an FPGA - specifically the carry chain - to create what is (in effect) an analog delay line. High-speed pulses travel down the chain in a "wave." For instance, a pulse train has been demonstrated from a 1- GHz source reliably traveling down the carry chain. The size of the carry chain is over 10 ns in the time domain. Thus, multiple pulses will travel down the carry chain in a wave simultaneously. A register clocked by a low-skew clock takes a "snapshot" of the wave. Relatively simple logic can extract the pulses from the snapshot picture by detecting the transitions between logic states. The propagation delay of CMOS (complementary metal oxide semiconductor) logic circuits will differ and/or change as a result of temperature, voltage, age, radiation, and manufacturing variances. The time-to-digital conversion circuits can be calibrated with test signals, or the changes can be nulled by a separate on-die calibration channel, in a closed loop circuit.

  2. Time-reversal symmetric resolution of unity without background integrals in open quantum systems

    SciTech Connect

    Hatano, Naomichi; Ordonez, Gonzalo

    2014-12-15

    We present a new complete set of states for a class of open quantum systems, to be used in expansion of the Green’s function and the time-evolution operator. A remarkable feature of the complete set is that it observes time-reversal symmetry in the sense that it contains decaying states (resonant states) and growing states (anti-resonant states) parallelly. We can thereby pinpoint the occurrence of the breaking of time-reversal symmetry at the choice of whether we solve Schrödinger equation as an initial-condition problem or a terminal-condition problem. Another feature of the complete set is that in the subspace of the central scattering area of the system, it consists of contributions of all states with point spectra but does not contain any background integrals. In computing the time evolution, we can clearly see contribution of which point spectrum produces which time dependence. In the whole infinite state space, the complete set does contain an integral but it is over unperturbed eigenstates of the environmental area of the system and hence can be calculated analytically. We demonstrate the usefulness of the complete set by computing explicitly the survival probability and the escaping probability as well as the dynamics of wave packets. The origin of each term of matrix elements is clear in our formulation, particularly, the exponential decays due to the resonance poles.

  3. Integration of the GG model with SEBAL to produce time series of evapotranspiration of high spatial resolution at watershed scales

    NASA Astrophysics Data System (ADS)

    Long, Di; Singh, Vijay P.

    2010-11-01

    Lack of good quality satellite images because of cloud contamination or long revisit time severely degrades predictions of evapotranspiration (ET) time series at watershed/regional scales from satellite-based surface flux models. We integrate the feedback model developed by Granger and Gray (the GG model) with the Surface Energy Balance Algorithm for Land (SEBAL), with the objective to generate ET time series of high spatial resolution and reliable temporal distribution at watershed scales. First, SEBAL is employed to yield estimates of ET for the Baiyangdian watershed in a semihumid climatic zone in north China on cloud-free days, where there exists the complementary relationship (CR) between actual ET and pan ET. These estimates constitute input to the GG model to inversely derive the relationship between the relative evaporation and the relative drying power of the air. Second, the modified GG model is used to yield ET time series on a daily basis simply by using routine meteorological data and Moderate Resolution Imaging Spectroradiometer (MODIS) albedo and leaf area index products. Results suggest that the modified GG model that has incorporated remotely sensed ET can effectively extend remote sensing based ET to days without images and improve spatial representation of ET at watershed scales. Utility of the evaporative fraction method and the crop coefficients approaches to extrapolate ET time series depends largely on the number and interval of good quality satellite images. Comparison of ET time series from the two techniques and the proposed integration method for days with daily net radiation larger than 100 W m-2 and corresponding pan ET clearly shows that only the integration method can exhibit an asymmetric CR at the watershed scale and daily time scale. Validation performed using hydrologic budget calculations indicate that the proposed method has the highest accuracy in terms of annual estimates of ET for both watersheds in north China.

  4. Deployment of High Resolution Real-Time Distribution Level Metering on Maui: Preprint

    SciTech Connect

    Bank, J.

    2013-01-01

    In order to support the ongoing Maui Smart Grid demonstration project advanced metering has been deployed at the distribution transformer level in Maui Electric Company's Kihei Circuit on the Island of Maui. This equipment has been custom designed to provide accurately time-stamped Phasor and Power Quality data in real time. Additionally, irradiance sensors have been deployed at a few selected locations in proximity to photovoltaic (PV) installations. The received data is being used for validation of existing system models and for impact studies of future system hardware. Descriptions of the hardware and its installation, and some preliminary metering results are presented. Real-time circuit visualization applications for the data are also under development.

  5. State-wide space-time water table mapping: cautionary tales, tribulations and resolution

    NASA Astrophysics Data System (ADS)

    Peterson, T. J.; Cheng, X.; Carrara, E.; Western, A. W.; Costelloe, J. F.; Frost, A. J.; McAuley, C. V.

    2015-12-01

    Historically, insufficient quantitative value has been derived from state groundwater monitoring networks. Water level data are occasionally used for calibrating local scale groundwater models and for graphical analysis, but very rarely are they used to identify regional groundwater processes and quantify changes in groundwater dynamics over time. Potentiometric maps have occasionally been derived to assist understanding of regional processes but generally they are derived for one point in time, often simply using an average water level over a year or season. Consequently, dynamics of regional groundwater over time has been compromised. Kriging with external drift (KED) has been a widely adopted approach for regional scale potentiometric mapping in recent years. However, it has a number of unacknowledged fundamental weaknesses - specifically, excessive noise in the head, sensitivity to observation errors and questionable estimation in upland regions and in coastal regions dominated by radial flow. These weaknesses are illustrated and then a multivariate localised colocated cokriging approach is proposed that locally reduces the excessive noise from KED and incorporates the coast line and streams into the estimation. Combined with the temporal interpolation of groundwater head (Peterson & Western, 2014), the approach allows regional scale mapping for a single point in time. To illustrate the approach, the monthly water table level was mapped across Victoria, Australia, from 1985 to 2014. Using the maps, the location and the nature/magnitude of major changes in groundwater dynamics were identified and the surface-groundwater connectivity of major rivers was estimated over time. While geological knowledge can be incorporated, this approach allows data-driven insights to be derived from groundwater monitoring networks without the usual assumptions required for numerical groundwater modeling. Peterson, T. J., and A. W. Western (2014), Nonlinear time-series modeling of

  6. Is a 4-Bit Synaptic Weight Resolution Enough? – Constraints on Enabling Spike-Timing Dependent Plasticity in Neuromorphic Hardware

    PubMed Central

    Pfeil, Thomas; Potjans, Tobias C.; Schrader, Sven; Potjans, Wiebke; Schemmel, Johannes; Diesmann, Markus; Meier, Karlheinz

    2012-01-01

    Large-scale neuromorphic hardware systems typically bear the trade-off between detail level and required chip resources. Especially when implementing spike-timing dependent plasticity, reduction in resources leads to limitations as compared to floating point precision. By design, a natural modification that saves resources would be reducing synaptic weight resolution. In this study, we give an estimate for the impact of synaptic weight discretization on different levels, ranging from random walks of individual weights to computer simulations of spiking neural networks. The FACETS wafer-scale hardware system offers a 4-bit resolution of synaptic weights, which is shown to be sufficient within the scope of our network benchmark. Our findings indicate that increasing the resolution may not even be useful in light of further restrictions of customized mixed-signal synapses. In addition, variations due to production imperfections are investigated and shown to be uncritical in the context of the presented study. Our results represent a general framework for setting up and configuring hardware-constrained synapses. We suggest how weight discretization could be considered for other backends dedicated to large-scale simulations. Thus, our proposition of a good hardware verification practice may rise synergy effects between hardware developers and neuroscientists. PMID:22822388

  7. eWaterCycle: real time assimilation of massive data streams into a hyper-resolution global hydrological model

    NASA Astrophysics Data System (ADS)

    Hut, Rolf; Sutanudjaja, Edwin; Drost, Niels; Steele-Dunne, Susan; de Jong, Kor; van Beek, Ludovicus; van de Giesen, Nick; Bierkens, Marc

    2013-04-01

    This research is focused on the ICT challenges involved in assimilating massive remote sensing datasets into a hyper-resolution hydrology model. The development of a hyper-resolution (100m) global hydrological model has recently been put forward as a "Grand Challenge" for the hydrological community. PCR-GLOBWB is a unique hydrological model including lateral flow and groundwater as well as human intervention through water consumption, dams and reservoir operations. Over the past decade, remotely sensed states, parameters and fluxes have become available through satellite observations. Exponential growth can be anticipated in the volume of hydrologically useful remote sensing data given the current plans of JAXA, NASA and ESA with respect to Earth observation satellites. Real time assimilation of these data into a hyper-resolution hydrology model would allow us to constrain the estimated states and fluxes and improve the model forecasts. However, this poses significant hydrological and ICT challenges. This project is a unique collaboration between hydrologists, and the computer scientists of the Netherlands eScience Center. Together, we will explore existing and novel ICT technologies to address the CPU and memory requirements of running the forward model. In addition, we will add data assimilation to this model, requiring streaming, management and processing of massive remote sensing datasets, as well as running the model for large ensembles and performing assimilation on a global scale.

  8. Is a 4-bit synaptic weight resolution enough? - constraints on enabling spike-timing dependent plasticity in neuromorphic hardware.

    PubMed

    Pfeil, Thomas; Potjans, Tobias C; Schrader, Sven; Potjans, Wiebke; Schemmel, Johannes; Diesmann, Markus; Meier, Karlheinz

    2012-01-01

    Large-scale neuromorphic hardware systems typically bear the trade-off between detail level and required chip resources. Especially when implementing spike-timing dependent plasticity, reduction in resources leads to limitations as compared to floating point precision. By design, a natural modification that saves resources would be reducing synaptic weight resolution. In this study, we give an estimate for the impact of synaptic weight discretization on different levels, ranging from random walks of individual weights to computer simulations of spiking neural networks. The FACETS wafer-scale hardware system offers a 4-bit resolution of synaptic weights, which is shown to be sufficient within the scope of our network benchmark. Our findings indicate that increasing the resolution may not even be useful in light of further restrictions of customized mixed-signal synapses. In addition, variations due to production imperfections are investigated and shown to be uncritical in the context of the presented study. Our results represent a general framework for setting up and configuring hardware-constrained synapses. We suggest how weight discretization could be considered for other backends dedicated to large-scale simulations. Thus, our proposition of a good hardware verification practice may rise synergy effects between hardware developers and neuroscientists.

  9. HIGH-TIME-RESOLUTION MEASUREMENTS OF THE POLARIZATION OF THE CRAB PULSAR AT 1.38 GHz

    SciTech Connect

    Słowikowska, Agnieszka; Stappers, Benjamin W.; Harding, Alice K.; O'Dell, Stephen L.; Elsner, Ronald F.; Weisskopf, Martin C.; Van der Horst, Alexander J.

    2015-01-20

    Using the Westerbork Synthesis Radio Telescope, we obtained high-time-resolution measurements of the full polarization of the Crab pulsar. At a resolution of 1/8192 of the 34 ms pulse period (i.e., 4.1 μs), the 1.38 GHz linear-polarization measurements are in general agreement with previous lower-time-resolution 1.4 GHz measurements of linear polarization in the main pulse (MP), in the interpulse (IP), and in the low-frequency component (LFC). We find the MP and IP to be linearly polarized at about 24% and 21% with no discernible difference in polarization position angle. However, contrary to theoretical expectations and measurements in the visible, we find no evidence for significant variation (sweep) in the polarization position angle over the MP, the IP, or the LFC. We discuss the implications, which appear to be in contradiction to theoretical expectations. We also detect weak circular polarization in the MP and IP, and strong (≈20%) circular polarization in the LFC, which also exhibits very strong (≈98%) linear polarization at a position angle of 40° from that of the MP or IP. The properties are consistent with the LFC, which is a low-altitude component, and the MP and IP, which are high-altitude caustic components. Current models for the MP and IP emission do not readily account for the absence of pronounced polarization changes across the pulse. We measure IP and LFC pulse phases relative to the MP consistent with recent measurements, which have shown that the phases of these pulse components are evolving with time.

  10. High-time-resolution Measurements of the Polarization of the Crab Pulsar at 1.38 GHz

    NASA Astrophysics Data System (ADS)

    Słowikowska, Agnieszka; Stappers, Benjamin W.; Harding, Alice K.; O'Dell, Stephen L.; Elsner, Ronald F.; van der Horst, Alexander J.; Weisskopf, Martin C.

    2015-01-01

    Using the Westerbork Synthesis Radio Telescope, we obtained high-time-resolution measurements of the full polarization of the Crab pulsar. At a resolution of 1/8192 of the 34 ms pulse period (i.e., 4.1 μs), the 1.38 GHz linear-polarization measurements are in general agreement with previous lower-time-resolution 1.4 GHz measurements of linear polarization in the main pulse (MP), in the interpulse (IP), and in the low-frequency component (LFC). We find the MP and IP to be linearly polarized at about 24% and 21% with no discernible difference in polarization position angle. However, contrary to theoretical expectations and measurements in the visible, we find no evidence for significant variation (sweep) in the polarization position angle over the MP, the IP, or the LFC. We discuss the implications, which appear to be in contradiction to theoretical expectations. We also detect weak circular polarization in the MP and IP, and strong (≈20%) circular polarization in the LFC, which also exhibits very strong (≈98%) linear polarization at a position angle of 40° from that of the MP or IP. The properties are consistent with the LFC, which is a low-altitude component, and the MP and IP, which are high-altitude caustic components. Current models for the MP and IP emission do not readily account for the absence of pronounced polarization changes across the pulse. We measure IP and LFC pulse phases relative to the MP consistent with recent measurements, which have shown that the phases of these pulse components are evolving with time.

  11. [Study of cancer cells fluorescence lifetime based on picosecond time resolution].

    PubMed

    Chen, Bi-Fang; Liu, Tian-Fu

    2006-08-01

    The object of the present study was the ultrafast photodynamic processes of hematoporphyrin derivative (HPD) for diagnosis and therapy of cancer. Time-resolved fluorescence spectra of cancerous and normal cells were measured using an ultrashort pulse laser spectral technique and picosecond time-correlated single-photon counting system. The fast part of cancerous and normal cells fluorescence decay was approximately 150 and 300 ps, the fluorescence peak intensity of cancerous and normal cells decayed about 10% and 55% in 12 hour, the lifetime of cancerous and normal cells was about 824 and 1 798 ps by calculating date of fluorescence decay, and HPD stay time was about 17 and 6 days in the cancerous and normal cells sample respectively. The data show that cancerous cells were greatly intimate with HPD. The results obtained can be used as an important basis for the diagnosis of cancer based on ultrashort pulse laser spectral technique. The results will contribute to feebleness ultrafast fluorescence of biology sample for real time measurement. PMID:17058959

  12. Nonlinear spectroscopy in the near-field: time resolved spectroscopy and subwavelength resolution non-invasive imaging

    NASA Astrophysics Data System (ADS)

    Namboodiri, Mahesh; Khan, Tahirzeb; Karki, Khadga; Kazemi, Mehdi Mohammad; Bom, Sidhant; Flachenecker, Günter; Namboodiri, Vinu; Materny, Arnulf

    2014-04-01

    The combination of near-field microscopy along with nonlinear optical spectroscopic techniques is presented here. The scanning near-field imaging technique can be integrated with nonlinear spectroscopic techniques to improve spatial and axial resolution of the images. Additionally, ultrafast dynamics can be probed down to nano-scale dimension. The review shows some examples for this combination, which resulted in an exciton map and vibrational contrast images with sub-wavelength resolution. Results of two-color femtosecond time-resolved pump-probe experiments using scanning near-field optical microscopy (SNOM) on thin films of the organic semiconductor 3,4,9,10 Perylenetetracarboxylic dianhydride (PTCDA) are presented. While nonlinear Raman techniques have been used to obtain highly resolved images in combination with near-field microscopy, the use of femtosecond laser pulses in electronic resonance still constitutes a big challenge. Here, we present our first results on coherent anti-Stokes Raman scattering (fs-CARS) with femtosecond laser pulses detected in the near-field using SNOM. We demonstrate that highly spatially resolved images can be obtained from poly(3-hexylthiophene) (P3HT) nano-structures where the fs-CARS process was in resonance with the P3HT absorption and with characteristic P3HT vibrational modes without destruction of the samples. Sub-diffraction limited lateral resolution is achieved. Especially the height resolution clearly surpasses that obtained with standard microCARS. These results will be the basis for future investigations of mode-selective dynamics in the near-field.

  13. High-Resolution Genuinely Multidimensional Solution of Conservation Laws by the Space-Time Conservation Element and Solution Element Method

    NASA Technical Reports Server (NTRS)

    Himansu, Ananda; Chang, Sin-Chung; Yu, Sheng-Tao; Wang, Xiao-Yen; Loh, Ching-Yuen; Jorgenson, Philip C. E.

    1999-01-01

    In this overview paper, we review the basic principles of the method of space-time conservation element and solution element for solving the conservation laws in one and two spatial dimensions. The present method is developed on the basis of local and global flux conservation in a space-time domain, in which space and time are treated in a unified manner. In contrast to the modern upwind schemes, the approach here does not use the Riemann solver and the reconstruction procedure as the building blocks. The drawbacks of the upwind approach, such as the difficulty of rationally extending the 1D scalar approach to systems of equations and particularly to multiple dimensions is here contrasted with the uniformity and ease of generalization of the Conservation Element and Solution Element (CE/SE) 1D scalar schemes to systems of equations and to multiple spatial dimensions. The assured compatibility with the simplest type of unstructured meshes, and the uniquely simple nonreflecting boundary conditions of the present method are also discussed. The present approach has yielded high-resolution shocks, rarefaction waves, acoustic waves, vortices, ZND detonation waves, and shock/acoustic waves/vortices interactions. Moreover, since no directional splitting is employed, numerical resolution of two-dimensional calculations is comparable to that of the one-dimensional calculations. Some sample applications displaying the strengths and broad applicability of the CE/SE method are reviewed.

  14. Monitoring irrigation volumes using high-resolution NDVI image time series: calibration and validation in the Kairouan plain (Tunisia)

    NASA Astrophysics Data System (ADS)

    Saadi, S.; Simonneaux, V.; Boulet, G.; Mougenot, B.; Lili Chabaane, Z.

    2015-10-01

    The increasing availability of high resolution high repetitively VIS-NIR remote sensing, like the forthcoming Sentinel-2 mission to be launched in 2015, offers unprecedented opportunity to improve agricultural monitoring. In this study, regional evapotranspiration and crop water consumption were estimated over an irrigated area located in the Kairouan plain (central Tunisia) using the FAO-56 dual crop coefficient water balance model combined with NDVI image time series providing estimates of the actual basal crop coefficient (Kcb) and vegetation fraction cover. Three time series of high-resolution SPOT5 images have been acquired for the 2008-2009, 2011-2012 and 2012-2013 hydrological years. We also benefited from a SPOT4 time series acquired in the frame of the SPOT4-Take5 experiment. The SPOT5 images were radiometrically corrected, first, using the SMAC6s Algorithm, and then improved using invariant objects located on the scene. The method was first calibrated using ground measurements of evapotranspiration achieved using eddy-correlation devices installed on irrigated wheat and barley plots. For other crops for which no calibration data was available, parameters were taken from bibliography. Then, the model was run to spatialize irrigation over the whole area and a validation was done using cumulated seasonal water volumes obtained from ground survey for three irrigated perimeters. In a subsequent step, evapotranspiration estimates were obtained using a large aperture scintillometer and were used for an additional validation of the model outputs.

  15. Microwave and hard X-ray observations of a solar flare with a time resolution better than 100 ms

    NASA Technical Reports Server (NTRS)

    Kaufmann, P.; Costa, J. E. R.; Dennis, B. R.; Frost, K. J.; Orwig, L. E.; Kiplinger, A.; Strauss, F. M.

    1983-01-01

    Simultaneous microwave and X-ray observations are presented for a solar flare detected on 1980 May 8 starting at 1937 UT. The X-ray observations were made with the Hard X-ray Burst Spectrometer on the Solar Maximum Mission and covered the energy range from 28-490 keV with a time resolution of 10 ms. The microwave observations were made with the 5 and 45 foot antennas at the Itapetinga Radio Obervatory at frequencies of 7 and 22 GHz, with time resolutions of 100 ms and 1 ms respectively. Detailed correlation analysis of the different time profiles of the event show that the major impulsive in the X-ray flux preceded the corresponding microwave peaks at 22 GHz by about 240 ms. For this particular burst the 22 GHz peaks preceded the 7 GHz by about 1.5s. Observed delays of the microwave peaks are too large for a simple electron beam model but they can be reconciled with the speeds of shock waves in a thermal model. Previously announced in STAR as N82-30215

  16. Widefield Two-Photon Excitation without Scanning: Live Cell Microscopy with High Time Resolution and Low Photo-Bleaching

    PubMed Central

    Amor, Rumelo; McDonald, Alison; Trägårdh, Johanna; Robb, Gillian; Wilson, Louise; Abdul Rahman, Nor Zaihana; Dempster, John; Amos, William Bradshaw; Bushell, Trevor J.; McConnell, Gail

    2016-01-01

    We demonstrate fluorescence imaging by two-photon excitation without scanning in biological specimens as previously described by Hwang and co-workers, but with an increased field size and with framing rates of up to 100 Hz. During recordings of synaptically-driven Ca2+ events in primary rat hippocampal neurone cultures loaded with the fluorescent Ca2+ indicator Fluo-4 AM, we have observed greatly reduced photo-bleaching in comparison with single-photon excitation. This method, which requires no costly additions to the microscope, promises to be useful for work where high time-resolution is required. PMID:26824845

  17. Widefield Two-Photon Excitation without Scanning: Live Cell Microscopy with High Time Resolution and Low Photo-Bleaching.

    PubMed

    Amor, Rumelo; McDonald, Alison; Trägårdh, Johanna; Robb, Gillian; Wilson, Louise; Abdul Rahman, Nor Zaihana; Dempster, John; Amos, William Bradshaw; Bushell, Trevor J; McConnell, Gail

    2016-01-01

    We demonstrate fluorescence imaging by two-photon excitation without scanning in biological specimens as previously described by Hwang and co-workers, but with an increased field size and with framing rates of up to 100 Hz. During recordings of synaptically-driven Ca(2+) events in primary rat hippocampal neurone cultures loaded with the fluorescent Ca(2+) indicator Fluo-4 AM, we have observed greatly reduced photo-bleaching in comparison with single-photon excitation. This method, which requires no costly additions to the microscope, promises to be useful for work where high time-resolution is required.

  18. Magnetic dynamics studied by high-resolution electron spectroscopy and time-resolved electron microscopy

    NASA Astrophysics Data System (ADS)

    Jayaraman, Rajeswari

    Future information technology requires an increased magnetically encoded data density and novel electromagnetic modes of data transfer. While to date magnetic properties are observed and characterized mostly statically, the need emerges to monitor and capture their fast dynamics. In this talk, I will focus on the spin dynamics i.e. spin wave excitations and the dynamics of a new topological distribution of spins termed ``skyrmions''. Wave packets of spin waves offer the unique capability to transport a quantum bit, the spin, without the transport of charge or mass. Here, large wave-vector spin waves are of particular interest as they admit spin localization within a few nanometers. By using our recently developed electron energy loss spectrometer, we could study such spin waves in ultrathin films with an unprecedented energy resolution of 4 meV. By virtue of the finite penetration depth of low energy electrons, spin waves localized at interfaces between a substrate and a thin capping layer can be been studied yielding information about the exchange coupling between atoms at the interface. The quantization of spin waves with wave vectors perpendicular to the film gives rise to standing modes to which EELS has likewise access. Such studies when carried out as function of the film thickness again yield information on the layer dependence of the exchange coupling. Magnetic skyrmions are promising candidates as information carriers in logic or storage devices. Currently, little is known about the influence of disorder, defects, or external stimuli on the spatial distribution and temporal evolution of the skyrmion lattice. In this talk, I will describe the dynamical role of disorder in a large and flat thin film of Cu2OSeO3, exhibiting a skyrmion phase in an insulating material. We image up to 70,000 skyrmions by means of cryo-Lorentz Transmission Electron Microscopy as a function of the applied magnetic field. In the skyrmion phase, dislocations are shown to cause the

  19. Real-time visual sensing system achieving high-speed 3D particle tracking with nanometer resolution.

    PubMed

    Cheng, Peng; Jhiang, Sissy M; Menq, Chia-Hsiang

    2013-11-01

    This paper presents a real-time visual sensing system, which is created to achieve high-speed three-dimensional (3D) motion tracking of microscopic spherical particles in aqueous solutions with nanometer resolution. The system comprises a complementary metal-oxide-semiconductor (CMOS) camera, a field programmable gate array (FPGA), and real-time image processing programs. The CMOS camera has high photosensitivity and superior SNR. It acquires images of 128×120 pixels at a frame rate of up to 10,000 frames per second (fps) under the white light illumination from a standard 100 W halogen lamp. The real-time image stream is downloaded from the camera directly to the FPGA, wherein a 3D particle-tracking algorithm is implemented to calculate the 3D positions of the target particle in real time. Two important objectives, i.e., real-time estimation of the 3D position matches the maximum frame rate of the camera and the timing of the output data stream of the system is precisely controlled, are achieved. Two sets of experiments were conducted to demonstrate the performance of the system. First, the visual sensing system was used to track the motion of a 2 μm polystyrene bead, whose motion was controlled by a three-axis piezo motion stage. The ability to track long-range motion with nanometer resolution in all three axes is demonstrated. Second, it was used to measure the Brownian motion of the 2 μm polystyrene bead, which was stabilized in aqueous solution by a laser trapping system. PMID:24216655

  20. Detection system for high-resolution gamma radiation spectroscopy with neutron time-of-flight filtering

    DOEpatents

    Dioszegi, Istvan; Salwen, Cynthia; Vanier, Peter

    2014-12-30

    A .gamma.-radiation detection system that includes at least one semiconductor detector such as HPGe-Detector, a position-sensitive .alpha.-Detector, a TOF Controller, and a Digitizer/Integrator. The Digitizer/Integrator starts to process the energy signals of a .gamma.-radiation sent from the HPGe-Detector instantly when the HPGe-Detector detects the .gamma.-radiation. Subsequently, it is determined whether a coincidence exists between the .alpha.-particles and .gamma.-radiation signal, based on a determination of the time-of-flight of neutrons obtained from the .alpha.-Detector and the HPGe-Detector. If it is determined that the time-of-flight falls within a predetermined coincidence window, the Digitizer/Integrator is allowed to continue and complete the energy signal processing. If, however, there is no coincidence, the Digitizer/Integrator is instructed to be clear and reset its operation instantly.

  1. The sub 60 ps timing resolution using large area silicon avalanche diodes

    NASA Astrophysics Data System (ADS)

    Hauger, A.; Hirsch, A.; Porile, N.; Scharenberg, R.; Stringfellow, B. C.; Tincknell, M.; Rai, G.

    1992-10-01

    The new generation of planned experiments in high energy and nuclear physics requires high pixel density time-of-flight detection systems which mark the occurrence of an event with sub-100 ps accuracy. Conventional fast phototubes and scintillators do not easily lend themselves to large scale mechanical and electrical integration and generally prove to be very expensive. As an alternative technology, we report on the development and optimization of Silicon Avalanche Diodes (AVD's). The project is in part strongly motivated by the STAR experiment planned for the Relativistic Heavy Ion Collider (RHIC) facility at BNL. The time-of-flight component of STAR is expected to operate in a 0.5T magnetic field and is highly segmented.

  2. Direct picosecond time resolution of unimolecular reactions initiated by local mode excitation

    NASA Technical Reports Server (NTRS)

    Scherer, N. F.; Doany, F. E.; Zewail, A. H.; Perry, J. W.

    1986-01-01

    Attention is given to the first results of direct, picosec measurements of the Delta-nu(OH) 5 local mode transition of H2O2. These time-resolved studies yield a direct measure of the unimolecular dissociation rate, and furnish a lower limit for the rate of energy redistribution from the OH stretch to the O-O reaction coordinate. The data thus determined may be used to ascertain the domain of validity for statistical unimolecular reaction rate theories.

  3. Ancient mitochondrial DNA provides high-resolution time scale of the peopling of the Americas.

    PubMed

    Llamas, Bastien; Fehren-Schmitz, Lars; Valverde, Guido; Soubrier, Julien; Mallick, Swapan; Rohland, Nadin; Nordenfelt, Susanne; Valdiosera, Cristina; Richards, Stephen M; Rohrlach, Adam; Romero, Maria Inés Barreto; Espinoza, Isabel Flores; Cagigao, Elsa Tomasto; Jiménez, Lucía Watson; Makowski, Krzysztof; Reyna, Ilán Santiago Leboreiro; Lory, Josefina Mansilla; Torrez, Julio Alejandro Ballivián; Rivera, Mario A; Burger, Richard L; Ceruti, Maria Constanza; Reinhard, Johan; Wells, R Spencer; Politis, Gustavo; Santoro, Calogero M; Standen, Vivien G; Smith, Colin; Reich, David; Ho, Simon Y W; Cooper, Alan; Haak, Wolfgang

    2016-04-01

    The exact timing, route, and process of the initial peopling of the Americas remains uncertain despite much research. Archaeological evidence indicates the presence of humans as far as southern Chile by 14.6 thousand years ago (ka), shortly after the Pleistocene ice sheets blocking access from eastern Beringia began to retreat. Genetic estimates of the timing and route of entry have been constrained by the lack of suitable calibration points and low genetic diversity of Native Americans. We sequenced 92 whole mitochondrial genomes from pre-Columbian South American skeletons dating from 8.6 to 0.5 ka, allowing a detailed, temporally calibrated reconstruction of the peopling of the Americas in a Bayesian coalescent analysis. The data suggest that a small population entered the Americas via a coastal route around 16.0 ka, following previous isolation in eastern Beringia for ~2.4 to 9 thousand years after separation from eastern Siberian populations. Following a rapid movement throughout the Americas, limited gene flow in South America resulted in a marked phylogeographic structure of populations, which persisted through time. All of the ancient mitochondrial lineages detected in this study were absent from modern data sets, suggesting a high extinction rate. To investigate this further, we applied a novel principal components multiple logistic regression test to Bayesian serial coalescent simulations. The analysis supported a scenario in which European colonization caused a substantial loss of pre-Columbian lineages. PMID:27051878

  4. Ancient mitochondrial DNA provides high-resolution time scale of the peopling of the Americas

    PubMed Central

    Llamas, Bastien; Fehren-Schmitz, Lars; Valverde, Guido; Soubrier, Julien; Mallick, Swapan; Rohland, Nadin; Nordenfelt, Susanne; Valdiosera, Cristina; Richards, Stephen M.; Rohrlach, Adam; Romero, Maria Inés Barreto; Espinoza, Isabel Flores; Cagigao, Elsa Tomasto; Jiménez, Lucía Watson; Makowski, Krzysztof; Reyna, Ilán Santiago Leboreiro; Lory, Josefina Mansilla; Torrez, Julio Alejandro Ballivián; Rivera, Mario A.; Burger, Richard L.; Ceruti, Maria Constanza; Reinhard, Johan; Wells, R. Spencer; Politis, Gustavo; Santoro, Calogero M.; Standen, Vivien G.; Smith, Colin; Reich, David; Ho, Simon Y. W.; Cooper, Alan; Haak, Wolfgang

    2016-01-01

    The exact timing, route, and process of the initial peopling of the Americas remains uncertain despite much research. Archaeological evidence indicates the presence of humans as far as southern Chile by 14.6 thousand years ago (ka), shortly after the Pleistocene ice sheets blocking access from eastern Beringia began to retreat. Genetic estimates of the timing and route of entry have been constrained by the lack of suitable calibration points and low genetic diversity of Native Americans. We sequenced 92 whole mitochondrial genomes from pre-Columbian South American skeletons dating from 8.6 to 0.5 ka, allowing a detailed, temporally calibrated reconstruction of the peopling of the Americas in a Bayesian coalescent analysis. The data suggest that a small population entered the Americas via a coastal route around 16.0 ka, following previous isolation in eastern Beringia for ~2.4 to 9 thousand years after separation from eastern Siberian populations. Following a rapid movement throughout the Americas, limited gene flow in South America resulted in a marked phylogeographic structure of populations, which persisted through time. All of the ancient mitochondrial lineages detected in this study were absent from modern data sets, suggesting a high extinction rate. To investigate this further, we applied a novel principal components multiple logistic regression test to Bayesian serial coalescent simulations. The analysis supported a scenario in which European colonization caused a substantial loss of pre-Columbian lineages. PMID:27051878

  5. Ancient mitochondrial DNA provides high-resolution time scale of the peopling of the Americas.

    PubMed

    Llamas, Bastien; Fehren-Schmitz, Lars; Valverde, Guido; Soubrier, Julien; Mallick, Swapan; Rohland, Nadin; Nordenfelt, Susanne; Valdiosera, Cristina; Richards, Stephen M; Rohrlach, Adam; Romero, Maria Inés Barreto; Espinoza, Isabel Flores; Cagigao, Elsa Tomasto; Jiménez, Lucía Watson; Makowski, Krzysztof; Reyna, Ilán Santiago Leboreiro; Lory, Josefina Mansilla; Torrez, Julio Alejandro Ballivián; Rivera, Mario A; Burger, Richard L; Ceruti, Maria Constanza; Reinhard, Johan; Wells, R Spencer; Politis, Gustavo; Santoro, Calogero M; Standen, Vivien G; Smith, Colin; Reich, David; Ho, Simon Y W; Cooper, Alan; Haak, Wolfgang

    2016-04-01

    The exact timing, route, and process of the initial peopling of the Americas remains uncertain despite much research. Archaeological evidence indicates the presence of humans as far as southern Chile by 14.6 thousand years ago (ka), shortly after the Pleistocene ice sheets blocking access from eastern Beringia began to retreat. Genetic estimates of the timing and route of entry have been constrained by the lack of suitable calibration points and low genetic diversity of Native Americans. We sequenced 92 whole mitochondrial genomes from pre-Columbian South American skeletons dating from 8.6 to 0.5 ka, allowing a detailed, temporally calibrated reconstruction of the peopling of the Americas in a Bayesian coalescent analysis. The data suggest that a small population entered the Americas via a coastal route around 16.0 ka, following previous isolation in eastern Beringia for ~2.4 to 9 thousand years after separation from eastern Siberian populations. Following a rapid movement throughout the Americas, limited gene flow in South America resulted in a marked phylogeographic structure of populations, which persisted through time. All of the ancient mitochondrial lineages detected in this study were absent from modern data sets, suggesting a high extinction rate. To investigate this further, we applied a novel principal components multiple logistic regression test to Bayesian serial coalescent simulations. The analysis supported a scenario in which European colonization caused a substantial loss of pre-Columbian lineages.

  6. STS-37 payload - Gamma Ray Observatory (GRO) - on RMS in OV-104's payload bay

    NASA Technical Reports Server (NTRS)

    1991-01-01

    During STS-37 deployment, the Gamma Ray Observatory (GRO), the mission's primary payload, is grappled by the remote manipulator system (RMS) arm and lifted above Atlantis', Orbiter Vehicle (OV) 104's, payload bay (PLB). Visible under GRO is the stowed high gain antenna (HGA). Four of the eight Burst and Transient Source Experiment (BATSE) detectors appear on GRO's corners (top and bottom). The Energetic Gamma Ray Experiment Telescope (EGRET) is visible on top of the GRO satellite. Other PLB-mounted experiments include the manipulator foot restraint (MFR) with grapple fixture (on starboard side), the ascent particle monitor (APM) (on starboard side), and the crew and equipment translation aid (CETA) track. OV-104's wings appear on either side of GRO with the vertical tail extending above it in the background.

  7. Rotating system for four-dimensional transverse rms-emittance measurements

    NASA Astrophysics Data System (ADS)

    Xiao, C.; Maier, M.; Du, X. N.; Gerhard, P.; Groening, L.; Mickat, S.; Vormann, H.

    2016-07-01

    Knowledge of the transverse four-dimensional beam rms parameters is essential for applications that involve lattice elements that couple the two transverse degrees of freedom (planes). Of special interest is the elimination of interplane correlations to reduce the projected emittances. A dedicated rotating system for emittance measurements (ROSE) has been proposed, developed, and successfully commissioned to fully determine the four-dimensional beam matrix. This device has been used at the high charge injector (HLI) at GSI in a beam line which is composed of a skew quadrupole triplet, a normal quadrupole doublet, and ROSE. Mathematical algorithms, measurements, and the analysis of errors and the decoupling capability for ion beams of 83Kr 13+ at 1.4 MeV /u are reported in this paper.

  8. Angular and RMS delay spread modeling in view of THz indoor communication systems

    NASA Astrophysics Data System (ADS)

    Priebe, Sebastian; Jacob, Martin; Kürner, Thomas

    2014-03-01

    Future wireless communication systems will most likely be operated at carrier frequencies above 300 GHz, where the indoor radio channel behaves entirely differently compared to legacy radio communication frequencies. Being highly relevant for system performance evaluations and channel modeling, the spatial as well as the temporal dispersions are studied for a representative office wireless LAN scenario in this paper. Ray tracing serves as the means for the accurate simulation of the THz radio wave propagation. Simple stochastic models are derived to approximate and reproduce the distance-dependent behavior of the angular spread as well as of the RMS delay spread. Based on the results, the maximum symbol rates achievable without any intersymbol interference are quantified and can be shown to reach up to several 100 GSymbols/s provided that highly directive antennas are used.

  9. High spatial and temporal resolution retrospective cine cardiovascular magnetic resonance from shortened free breathing real-time acquisitions

    PubMed Central

    2013-01-01

    Background Cine cardiovascular magnetic resonance (CMR) is challenging in patients who cannot perform repeated breath holds. Real-time, free-breathing acquisition is an alternative, but image quality is typically inferior. There is a clinical need for techniques that achieve similar image quality to the segmented cine using a free breathing acquisition. Previously, high quality retrospectively gated cine images have been reconstructed from real-time acquisitions using parallel imaging and motion correction. These methods had limited clinical applicability due to lengthy acquisitions and volumetric measurements obtained with such methods have not previously been evaluated systematically. Methods This study introduces a new retrospective reconstruction scheme for real-time cine imaging which aims to shorten the required acquisition. A real-time acquisition of 16-20s per acquired slice was inputted into a retrospective cine reconstruction algorithm, which employed non-rigid registration to remove respiratory motion and SPIRiT non-linear reconstruction with temporal regularization to fill in missing data. The algorithm was used to reconstruct cine loops with high spatial (1.3-1.8 × 1.8-2.1 mm2) and temporal resolution (retrospectively gated, 30 cardiac phases, temporal resolution 34.3 ± 9.1 ms). Validation was performed in 15 healthy volunteers using two different acquisition resolutions (256 × 144/192 × 128 matrix sizes). For each subject, 9 to 12 short axis and 3 long axis slices were imaged with both segmented and real-time acquisitions. The retrospectively reconstructed real-time cine images were compared to a traditional segmented breath-held acquisition in terms of image quality scores. Image quality scoring was performed by two experts using a scale between 1 and 5 (poor to good). For every subject, LAX and three SAX slices were selected and reviewed in the random order. The reviewers were blinded to the reconstruction approach and

  10. Impact of Atmospheric Attenuations Time Resolutions in Solar Radiation Derived from Satellite Imagery

    NASA Astrophysics Data System (ADS)

    Cony, Marco; Liria, Juan; Weisenberg, Ralf; Serrano, Enrique

    2014-05-01

    Accurate knowledge of solar irradiance components at the earth surface is of highly interest in many scientific and technology branches concerning meteorology, climate, agriculture and solar energy applications. In the specific case of solar energy systems the solar resource analysis with accuracy is a first step in every project since it is a required data for design, power output estimations, systems simulations and risk assessments. Solar radiation measurement availability is increasing both in spatial density and in historical archiving. However, it is still quite limited and most of the situations cannot make use of a long term ground database of high quality since solar irradiance is not generally measured where users need data. Satellite-derived solar radiation estimations are a powerful and valuable tool for solar resource assessment studies that have achieved a relatively high maturity due to years of developments and improvements. However, several sources of uncertainty are still present in satellite-derived methods. In particular, the strong influence of atmospheric attenuation information as input to the method is one of the main topics of improvement. Since solar radiation attenuation by atmospheric aerosols, and water vapor in a second place, is, after clouds, the second most important factor determining solar radiation, and particularly direct normal irradiance, the accurate knowledge of aerosol optical depth and water vapor content is relevant in the final output of satellite-derived methods. This present work, two different datasets we are used for extract atmospheric attenuation information. On the one hand the monthly mean values of the Linke turbidity factor from Meteotest database, which are twelve unique values of the Linke turbidity worldwide with a spatial resolution of 1/12º. On the other hand, daily values of AOD (Aerosol Optical Depth) at 550 nm, Angstrom alpha exponent and water vapor column were taken from a gridded database that

  11. Integrating Real-time and Manual Monitored Soil Moisture Data to Predict Hillslope Soil Moisture Variations with High Temporal Resolutions

    NASA Astrophysics Data System (ADS)

    Zhu, Qing; Lv, Ligang; Zhou, Zhiwen; Liao, Kaihua

    2016-04-01

    Spatial-temporal variability of soil moisture 15 has been remaining an challenge to be better understood. A trade-off exists between spatial coverage and temporal resolution when using the manual and real-time soil moisture monitoring methods. This restricted the comprehensive and intensive examination of soil moisture dynamics. In this study, we aimed to integrate the manual and real-time monitored soil moisture to depict the hillslope dynamics of soil moisture with good spatial coverage and temporal resolution. Linear (stepwise multiple linear regression-SMLR) and non-linear models (support vector machines-SVM) were used to predict soil moisture at 38 manual sites (collected 1-2 times per month) with soil moisture automatically collected at three real-time monitoring sites (collected every 5 mins). By comparing the accuracies of SMLR and SVM for each manual site, optimal soil moisture prediction model of this site was then determined. Results show that soil moisture at these 38 manual sites can be reliably predicted (root mean square errors<0.035 m3 m-3) using this approach. Absence or occurrence of subsurface flow can probably influence the choosing of SMLR or SVM in the prediction, respectively. Depth to bedrock, elevation, topographic wetness index, profile curvature, and relative difference of soil moisture and its standard deviation influenced the selection of prediction model since they related to the dynamics of soil water distribution and movement. By using this approach, hillslope soil moisture spatial distributions at un-sampled times and dates were predicted after a typical rainfall event. Missing information of hillslope soil moisture dynamics was then acquired successfully. This can be benefit for determining the hot spots and moments of soil water movement, as well as designing the proper soil moisture monitoring plan at the field scale.

  12. Real-time Data Processing and Visualization for the Airborne Scanning High-resolution Interferometer Sounder (S-HIS)

    NASA Astrophysics Data System (ADS)

    Taylor, J. K.; Revercomb, H. E.; Hoese, D.; Garcia, R. K.; Smith, W. L.; Weisz, E.; Tobin, D. C.; Best, F. A.; Knuteson, R. O.; Sullivan, D. V.; Barnes, C. M.; Van Gilst, D. P.

    2015-12-01

    The Hurricane and Severe Storm Sentinel (HS3) is a five-year NASA mission targeted to enhance the understanding of the formation and evolution of hurricanes in the Atlantic basin. Measurements were made from two NASA Global Hawk Unmanned Aircraft Systems (UAS) during the 2012 through 2014 hurricane seasons, with flights conducted from the NASA Wallops Flight Facility. The Global Hawk aircraft are capable of high altitude flights with durations of up to 30 hours, which allow extensive observations over distant storms, not typically possible with manned aircraft. The two NASA Global Hawks were equipped with instrument suites to study the storm environment, and inner core structure and processes, respectively. The Scanning High-resolution Interferometer Sounder (S-HIS), designed and built by the University of Wisconsin (UW) Space Science and Engineering Center (SSEC), measures emitted thermal radiation at high spectral resolution between 3.3 and 18 microns. The radiance measurements are used to obtain temperature and water vapor profiles of the Earth's atmosphere. The S-HIS spatial resolution is 2 km at nadir, across a 40 km ground swath from a nominal altitude of 20 kilometers. Since 1998, the S-HIS has participated in 33 field campaigns and has proven to be extremely dependable, effective, and highly accurate. It has flown on the NASA ER-2, DC-8, Proteus, WB-57, and Global Hawk airborne platforms. The UW S-HIS infrared sounder instrument is equipped with a real-time ground data processing system capable of delivering atmospheric profiles, radiance data, and engineering status to mission support scientists - all within less than one minute from the time of observation. This ground data processing system was assembled by a small team using existing software and proven practical techniques similar to a satellite ground system architecture. This summary outlines the design overview for the system and illustrates the data path, content, and outcomes.

  13. Real-time high-resolution measurement of collagen alignment in dynamically loaded soft tissue.

    PubMed

    York, Timothy; Kahan, Lindsey; Lake, Spencer P; Gruev, Viktor

    2014-06-01

    A technique for creating maps of the direction and strength of fiber alignment in collagenous soft tissues is presented. The method uses a division of focal plane polarimeter to measure circularly polarized light transmitted through the tissue. The architecture of the sensor allows measurement of the retardance and fiber alignment at the full frame rate of the sensor without any moving optics. The technique compares favorably to the standard method of using a rotating polarizer. How the new technique enables real-time capture of the full angular spread of fiber alignment and retardance under various cyclic loading conditions is illustrated. PMID:24972359

  14. Direct mapping of ion diffusion times on LiCoO2 surfaces with nanometer resolution

    SciTech Connect

    Guo, Senli; Jesse, Stephen; Kalnaus, Sergiy; Balke, Nina; Daniel, Claus; Kalinin, Sergei V

    2011-01-01

    The strong coupling between the molar volume and mobile ion concentration in ionically-conductive solids is used for spatially-resolved studies of ionic transport on the polycrystalline LiCoO2 surface by time-resolved spectroscopy. Strong variability between ionic transport at the grain boundaries and within the grains is observed, and the relationship between relaxation and hysteresis loop formation is established. The use of the strain measurements allows ionic transport be probed on the nanoscale, and suggests enormous potential for probing ionic materials and devices.

  15. A real-time inverse quantised transform for multi-standard with dynamic resolution support

    NASA Astrophysics Data System (ADS)

    Sun, Chi-Chia; Lin, Chun-Ying; Zhang, Ce

    2016-06-01

    In this paper, a real-time configurable intelligent property (IP) core is presented for image/video decoding process in compatibility with the standard MPEG-4 Visual and the standard H.264/AVC. The inverse quantised discrete cosine and integer transform can be used to perform inverse quantised discrete cosine transform and inverse quantised inverse integer transforms which only required shift and add operations. Meanwhile, COordinate Rotation DIgital Computer iterations and compensation steps are adjustable in order to compensate for the video compression quality regarding various data throughput. The implementations are embedded in publicly available software XVID Codes 1.2.2 for the standard MPEG-4 Visual and the H.264/AVC reference software JM 16.1, where the experimental results show that the balance between the computational complexity and video compression quality is retained. At the end, FPGA synthesised results show that the proposed IP core can bring advantages to low hardware costs and also provide real-time performance for Full HD and 4K-2K video decoding.

  16. Automatic, Real-Time Algorithms for Anomaly Detection in High Resolution Satellite Imagery

    NASA Astrophysics Data System (ADS)

    Srivastava, A. N.; Nemani, R. R.; Votava, P.

    2008-12-01

    Earth observing satellites are generating data at an unprecedented rate, surpassing almost all other data intensive applications. However, most of the data that arrives from the satellites is not analyzed directly. Rather, multiple scientific teams analyze only a small fraction of the total data available in the data stream. Although there are many reasons for this situation one paramount concern is developing algorithms and methods that can analyze the vast, high dimensional, streaming satellite images. This paper describes a new set of methods that are among the fastest available algorithms for real-time anomaly detection. These algorithms were built to maximize accuracy and speed for a variety of applications in fields outside of the earth sciences. However, our studies indicate that with appropriate modifications, these algorithms can be extremely valuable for identifying anomalies rapidly using only modest computational power. We review two algorithms which are used as benchmarks in the field: Orca, One-Class Support Vector Machines and discuss the anomalies that are discovered in MODIS data taken over the Central California region. We are especially interested in automatic identification of disturbances within the ecosystems (e,g, wildfires, droughts, floods, insect/pest damage, wind damage, logging). We show the scalability of the algorithms and demonstrate that with appropriately adapted technology, the dream of real-time analysis can be made a reality.

  17. Flight assessment of a real time multi-resolution image fusion system for use in degraded visual environments

    NASA Astrophysics Data System (ADS)

    Smith, M. I.; Sadler, J. R. E.

    2007-04-01

    Military helicopter operations are often constrained by environmental conditions, including low light levels and poor weather. Recent experience has also shown the difficulty presented by certain terrain when operating at low altitude by day and night. For example, poor pilot cues over featureless terrain with low scene contrast, together with obscuration of vision due to wind-blown and re-circulated dust at low level (brown out). These sorts of conditions can result in loss of spatial awareness and precise control of the aircraft. Atmospheric obscurants such as fog, cloud, rain and snow can similarly lead to hazardous situations and reduced situational awareness. Day Night All Weather (DNAW) systems applied research sponsored by UK Ministry of Defence (MoD) has developed a multi-resolution real time Image Fusion system that has been flown as part of a wider flight trials programme investigating increased situational awareness. Dual-band multi-resolution adaptive image fusion was performed in real-time using imagery from a Thermal Imager and a Low Light TV, both co-bore sighted on a rotary wing trials aircraft. A number of sorties were flown in a range of climatic and environmental conditions during both day and night. (Neutral density filters were used on the Low Light TV during daytime sorties.) This paper reports on the results of the flight trial evaluation and discusses the benefits offered by the use of Image Fusion in degraded visual environments.

  18. An 11-bit and 39 ps resolution time-to-digital converter for ADPLL in digital television

    NASA Astrophysics Data System (ADS)

    Liu, Wei; (Ruth) Li, Wei; Ren, P.; Lin, C. L.; Zhang, Shengdong; Wang, Yangyuan

    2010-04-01

    We propose and demonstrate an 11-bit time-to-digital converter (TDC) for all-digital phase-locked loops (ADPLLs) in digital television. The proposed TDC converts the width of the input pulse into digital output with the tap space of the outputs of a free-running ring oscillator (FRO) being the conversion resolution. The FRO is in a structure of coiled cell array and the TDC core is symmetrical in the input structure. This leads to equally spaced taps in the reference clocks and thereby a high TDC conversion linearity. The TDC is fabricated in 0.13 μm CMOS process and the chip area is 0.025 mm2. The measurement results show that the TDC has a conversion resolution of 39 ps at 1.2 V power supply and a 4.5 ns dead time in the 11-bits output case. Both the differential non-linearity (DNL) and integral non-linearity (INL) are below 0.5 LSB. The power consumption of the whole circuit is 4.2 mW.

  19. Unravelling complex processes during effusive volcanic eruptions using high resolution time-lapse imagery

    NASA Astrophysics Data System (ADS)

    Pinkerton, H.; James, M. R.; Applegarth, L. J.

    2010-12-01

    While lava flow models are being used successfully to predict areas that are liable to be covered during effusive eruptions, lavas that erupt for more than a few weeks have the potential to develop lava tubes, ephemeral vents and accidental breaches leading to new lava flow pathways. The processes resulting in each of these are not fully understood. Some of these may be related to variations in effusion rate during the eruption; others may be topographically-controlled. There is a therefore a need for a detailed analysis of the development of flow fields to improve our understanding of the factors that control maximum flow length of individual flows, ephemeral vent formation, accidental breaches, and the transition from channelled flows to tube-fed flows. During the final month of the 13 May 2008 to 6 July 2009 eruption into the Valle del Bove on Etna, four Canon EOS 450D cameras (3 visible and one modified to collect infrared images) were installed at critical locations around the rim of the Valle del Bove (Schiena dell’ Àsino, Monte Zoccolaro and Pizzi Deneri) to record the emplacement and development of lava flows erupted during this period. Some of the cameras collected images every 5 minutes, while others collected images every 15 minutes. During this time, active lava flows were restricted to the upper part of a large delta, individual flows lasted between a few hours and a few days and they had lengths ranging from tens to hundreds of metres. The resulting time-lapse images reveal significant reduction in mean flow lengths towards the end of the observation period; this is compatible with a marked decrease in effusion rate. Superimposed on this reduction, there were marked variations in effusion rate on shorter time periods. These short-term changes played a significant role in the development of breakouts and ephemeral vent formation and reactivation. The images also place constraints on the relative importance of factors controlling the maximum flow

  20. Front-end chip for Silicon Photomultiplier detectors with pico-second Time-of-Flight resolution

    NASA Astrophysics Data System (ADS)

    Stankova, V.; Briggl, K.; Chen, H.; Gil, A.; Harion, T.; Munwes, Y.; Shen, W.; Schultz-Coulon, H.-C.

    2016-07-01

    A mixed-mode readout Application Specific Integrated Circuit (STIC3) has been developed for high precision timing measurements with Silicon Photomultipliers (SiPM) for medical imaging and particle physics applications. The STiC3 is a 64-channel chip, with fully differential analog front-end for cross-talk and electronic noise immunity. The time and charge information from the SiPM signals are encrypted into two time stamps generated by integrated Time to Digital Converter (TDC) modules with 50 ps time binning. The TDC data is stored in an internal memory and transferred to a PC via a 160 MBit/s serial link using an 8/10 bit encoding. The chip provides an input bias tuning in a range of 0-900 mV to compensate the breakdown voltage variation of individual SiPMs. The TDC jitter together with the digital part is around 37 ps. A Coincidence Time Resolution (CTR) of 213.6 ps FWHM has been obtained with 3.1 × 3.1 × 15m2 LYSO:Ce scintillator crystals and Hamamatsu SiPM matrices (S12643-050CN(X)). Characterization measurements with the chip and its integration into the external plate of the EndoTOFPET-US prototype are presented.

  1. Detecting environmental change using time series, high resolution imagery and field work - a case study in the Sahel of Mali

    NASA Astrophysics Data System (ADS)

    Brandt, M.; Samimi, C.; Romankiewicz, C.; Spiekermann, R.

    2012-04-01

    Climatic changes and population pressure have caused major environmental change in the Sahel during the last fifty years. Many studies use coarse resolution NDVI time series such as GIMMS to detect environmental trends; however explanations for these trends remain largely unknown. We suggest a five-step methodology for the validation of trends with a case study on the Dogon Plateau, Mali. The first step is to monitor long-term trends with coarse scale time series. Instead of GIMMS, we use a combination of LTDR (derived from AVHRR) and SPOT VGT NDVI data, covering the period from 1982-today with a temporal resolution of 10 days and a spatial resolution of 5.6 km. Areas with significant trends are further analysed in a second step. Here we use a decomposed MODIS time series with a spatial resolution of 250 m. Due to the large scaled MODIS dataset, trends can be identified at a local scale / village level. Using very high resolution imagery (e.g. SPOT, Quickbird) areas of interest can be compared with pre-drought Corona-imagery. This offers a detailed overview of the environmental change at tree-level. Yet many explanations for the changes identified remain unclear. On-site field work provides information on the land use systems, vegetation composition and the current environmental condition. Still many explanations for change can only be speculated and hypothesized. For this reason, interviews with the local population are vital for providing missing details. In this case study, an area near Fiko is introduced and analysed, where significant negative NDVI-trends are observed at a coarse scale. Using the MODIS dataset, the spatial pattern shows areas with both positive and negative trends within the same area. A comparison of high resolution imagery with the Corona images show major land use changes over the past fifty years. What used to be dense bush cover has partially been converted to farmer managed agro-forestry and a significant proportion is now degraded land

  2. A decade-spanning high-resolution asynchronous optical sampling terahertz time-domain and frequency comb spectrometer.

    PubMed

    Good, Jacob T; Holland, Daniel B; Finneran, Ian A; Carroll, P Brandon; Kelley, Matthew J; Blake, Geoffrey A

    2015-10-01

    We present the design and capabilities of a high-resolution, decade-spanning ASynchronous OPtical Sampling (ASOPS)-based TeraHertz Time-Domain Spectroscopy (THz-TDS) instrument. Our system employs dual mode-locked femtosecond Ti:Sapphire oscillators with repetition rates offset locked at 100 Hz via a Phase-Locked Loop (PLL) operating at the 60th harmonic of the ∼80 MHz oscillator repetition rates. The respective time delays of the individual laser pulses are scanned across a 12.5 ns window in a laboratory scan time of 10 ms, supporting a time delay resolution as fine as 15.6 fs. The repetition rate of the pump oscillator is synchronized to a Rb frequency standard via a PLL operating at the 12th harmonic of the oscillator repetition rate, achieving milliHertz (mHz) stability. We characterize the timing jitter of the system using an air-spaced etalon, an optical cross correlator, and the phase noise spectrum of the PLL. Spectroscopic applications of ASOPS-THz-TDS are demonstrated by measuring water vapor absorption lines from 0.55 to 3.35 THz and acetonitrile absorption lines from 0.13 to 1.39 THz in a short pathlength gas cell. With 70 min of data acquisition, a 50 dB signal-to-noise ratio is achieved. The achieved root-mean-square deviation is 14.6 MHz, with a mean deviation of 11.6 MHz, for the measured water line center frequencies as compared to the JPL molecular spectroscopy database. Further, with the same instrument and data acquisition hardware, we use the ability to control the repetition rate of the pump oscillator to enable THz frequency comb spectroscopy (THz-FCS). Here, a frequency comb with a tooth width of 5 MHz is generated and used to fully resolve the pure rotational spectrum of acetonitrile with Doppler-limited precision. The oscillator repetition rate stability achieved by our PLL lock circuits enables sub-MHz tooth width generation, if desired. This instrument provides unprecedented decade-spanning, tunable resolution, from 80 MHz down to sub

  3. A decade-spanning high-resolution asynchronous optical sampling terahertz time-domain and frequency comb spectrometer.

    PubMed

    Good, Jacob T; Holland, Daniel B; Finneran, Ian A; Carroll, P Brandon; Kelley, Matthew J; Blake, Geoffrey A

    2015-10-01

    We present the design and capabilities of a high-resolution, decade-spanning ASynchronous OPtical Sampling (ASOPS)-based TeraHertz Time-Domain Spectroscopy (THz-TDS) instrument. Our system employs dual mode-locked femtosecond Ti:Sapphire oscillators with repetition rates offset locked at 100 Hz via a Phase-Locked Loop (PLL) operating at the 60th harmonic of the ∼80 MHz oscillator repetition rates. The respective time delays of the individual laser pulses are scanned across a 12.5 ns window in a laboratory scan time of 10 ms, supporting a time delay resolution as fine as 15.6 fs. The repetition rate of the pump oscillator is synchronized to a Rb frequency standard via a PLL operating at the 12th harmonic of the oscillator repetition rate, achieving milliHertz (mHz) stability. We characterize the timing jitter of the system using an air-spaced etalon, an optical cross correlator, and the phase noise spectrum of the PLL. Spectroscopic applications of ASOPS-THz-TDS are demonstrated by measuring water vapor absorption lines from 0.55 to 3.35 THz and acetonitrile absorption lines from 0.13 to 1.39 THz in a short pathlength gas cell. With 70 min of data acquisition, a 50 dB signal-to-noise ratio is achieved. The achieved root-mean-square deviation is 14.6 MHz, with a mean deviation of 11.6 MHz, for the measured water line center frequencies as compared to the JPL molecular spectroscopy database. Further, with the same instrument and data acquisition hardware, we use the ability to control the repetition rate of the pump oscillator to enable THz frequency comb spectroscopy (THz-FCS). Here, a frequency comb with a tooth width of 5 MHz is generated and used to fully resolve the pure rotational spectrum of acetonitrile with Doppler-limited precision. The oscillator repetition rate stability achieved by our PLL lock circuits enables sub-MHz tooth width generation, if desired. This instrument provides unprecedented decade-spanning, tunable resolution, from 80 MHz down to sub

  4. A decade-spanning high-resolution asynchronous optical sampling terahertz time-domain and frequency comb spectrometer

    NASA Astrophysics Data System (ADS)

    Good, Jacob T.; Holland, Daniel B.; Finneran, Ian A.; Carroll, P. Brandon; Kelley, Matthew J.; Blake, Geoffrey A.

    2015-10-01

    We present the design and capabilities of a high-resolution, decade-spanning ASynchronous OPtical Sampling (ASOPS)-based TeraHertz Time-Domain Spectroscopy (THz-TDS) instrument. Our system employs dual mode-locked femtosecond Ti:Sapphire oscillators with repetition rates offset locked at 100 Hz via a Phase-Locked Loop (PLL) operating at the 60th harmonic of the ˜80 MHz oscillator repetition rates. The respective time delays of the individual laser pulses are scanned across a 12.5 ns window in a laboratory scan time of 10 ms, supporting a time delay resolution as fine as 15.6 fs. The repetition rate of the pump oscillator is synchronized to a Rb frequency standard via a PLL operating at the 12th harmonic of the oscillator repetition rate, achieving milliHertz (mHz) stability. We characterize the timing jitter of the system using an air-spaced etalon, an optical cross correlator, and the phase noise spectrum of the PLL. Spectroscopic applications of ASOPS-THz-TDS are demonstrated by measuring water vapor absorption lines from 0.55 to 3.35 THz and acetonitrile absorption lines from 0.13 to 1.39 THz in a short pathlength gas cell. With 70 min of data acquisition, a 50 dB signal-to-noise ratio is achieved. The achieved root-mean-square deviation is 14.6 MHz, with a mean deviation of 11.6 MHz, for the measured water line center frequencies as compared to the JPL molecular spectroscopy database. Further, with the same instrument and data acquisition hardware, we use the ability to control the repetition rate of the pump oscillator to enable THz frequency comb spectroscopy (THz-FCS). Here, a frequency comb with a tooth width of 5 MHz is generated and used to fully resolve the pure rotational spectrum of acetonitrile with Doppler-limited precision. The oscillator repetition rate stability achieved by our PLL lock circuits enables sub-MHz tooth width generation, if desired. This instrument provides unprecedented decade-spanning, tunable resolution, from 80 MHz down to sub

  5. High Resolution Euler Solvers Based on the Space-Time Conservation Element and Solution Element Method

    NASA Technical Reports Server (NTRS)

    Wang, Xiao-Yen; Chow, Chuen-Yen; Chang, Sin-Chung

    1996-01-01

    The I-D, quasi I-D and 2-D Euler solvers based on the method of space-time conservation element and solution element are used to simulate various flow phenomena including shock waves, Mach stem, contact surface, expansion waves, and their intersections and reflections. Seven test problems are solved to demonstrate the capability of this method for handling unsteady compressible flows in various configurations. Numerical results so obtained are compared with exact solutions and/or numerical solutions obtained by schemes based on other established computational techniques. Comparisons show that the present Euler solvers can generate highly accurate numerical solutions to complex flow problems in a straightforward manner without using any ad hoc techniques in the scheme.

  6. 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

    We report observations of extremely large concentrations of molecular iodine (I2) measured in situ above a seaweed bed composed of laminaria digitata (90%) and laminaria hyperborea (10%) growing in its natural habitat. Measurements were made off the coast of Roscoff in Brittany, France, during day-time low tides on several days in September and November 2012 with the greatest tidal amplitudes. Iodine was quantified using a portable, battery-powered broadband cavity enhanced absorption spectrometer (BBCEAS) deployed from the in-shore research vessel "Aurelia" operated by the Station Biologique de Roscoff. For the 5 second integration times used here, the BBCEAS instrument has a detection limit for iodine of 12 pptv (parts per trillion by volume). The boat was anchored above the seaweed bed before it was exposed to air by the ebbing tide; the boat was grounded on the seaweed bed around the tidal minimum, and then refloated as the incoming tide covered the seaweed. I2 concentrations were strongly anti-correlated with water depth. Initially little I2 was seen above background levels whilst the blades of the seaweed plants were floating on the water surface. However several hundred pptv of I2 was observed within a few minutes of the plants' stipes breaking the surface and first blades coming to rest on rocks out of the water. Iodine concentrations increased further as the tide ebbed, typically peaking around 1500 pptv around the tidal minimum (by which time the seaweed had been exposed for 45 minutes). I2 concentrations decreased rapidly back to background levels as the returning tide submerged the seaweeds. The concentration profiles showed a lot of high frequency structure, with I2 concentrations commonly varying by a factor 2 (or more) within 60 seconds. Additionally the profiles of I2 emitted from the seaweeds immediately below the instrument's inlet typically sat on a smoothly-varying background of approximately 100 pptv, which we attribute to I2 from other more

  7. A New Non-Hausdorff Spacetime Model for Resolution of the Time Travel Paradoxes

    NASA Astrophysics Data System (ADS)

    Sharlow, Mark F.

    1998-03-01

    Physicists interested in chronology-violating spacetimes have considered various strategies for avoiding the time travel paradoxes which can arise in those spacetimes. One such strategy is the adoption of a branching (non-Hausdorff) topology for spacetime. Branching spacetime models also arise in other physical contexts, such as the many-worlds interpretation of quantum mechanics. A known objection to the idea of branching spacetime stems from the fact that an observer in such a spacetime may have multiple futures or pasts. In this paper I describe a new non-Hausdorff spacetime model in which each observer has a unique history. This model differs topologically from previous non-Hausdorff spacetime models in that is not aT1-space.

  8. A poly(dimethylsiloxane)-based device enabling time-lapse imaging with high spatial resolution

    SciTech Connect

    Hirano, Masahiko; Hoshida, Tetsushi; Sakaue-Sawano, Asako; Miyawaki, Atsushi

    2010-02-12

    We have developed a regulator-free device that enables long-term incubation of mammalian cells for epi-fluorescence imaging, based on a concept that the size of sample to be gassed and heated is reduced to observation scale. A poly(dimethylsiloxane) block stamped on a coverslip works as a long-lasting supplier of CO{sub 2}-rich gas to adjust bicarbonate-containing medium in a tiny chamber at physiological pH, and an oil-immersion objective warms cells across the coverslip. A time-lapse imaging experiment using HeLa cells stably expressing fluorescent cell-cycle indicators showed that the cells in the chamber proliferated with normal cell-cycle period over 2 days.

  9. Application of atomic layer deposited microchannel plates to imaging photodetectors with high time resolution

    NASA Astrophysics Data System (ADS)

    Siegmund, O. H. W.; McPhate, J. B.; Tremsin, A. S.; Vallerga, J. V.; Ertley, C. D.; Richner, N. J.; Gerard, T. M.; Frisch, H. J.; Elam, J. W.; Mane, A. U.; Wagner, R. G.; Minot, M. J.; O`Mahony, A.; Craven, C. A.

    2015-07-01

    Novel microchannel plates have been constructed using borosilicate glass micro-capillary array substrates with 20 μm and 10 μm pores and coated with resistive, and secondary electron emissive, layers by atomic layer deposition. Microchannel plates in 33 mm, 50 mm and 20 cm square formats have been made and tested. Although their amplification, imaging, and timing properties are comparable to standard glass microchannel plates, the background rates and lifetime characteristics are considerably improved. Sealed tube detectors based on the Planacon tube, and a 25 mm cross delay line readout tube with a GaN(Mg) opaque photocathode deposited on borosilicate microchannel plates have been fabricated. Considerable progress has also been made with 20 cm microchannel plates for a 20 cm format sealed tube sensor with strip-line readout that is being developed for Cherenkov light detection.

  10. Resolution of deep angiosperm phylogeny using conserved nuclear genes and estimates of early divergence times

    PubMed Central

    Zeng, Liping; Zhang, Qiang; Sun, Renran; Kong, Hongzhi; Zhang, Ning; Ma, Hong

    2014-01-01

    Angiosperms are the most successful plants and support human livelihood and ecosystems. Angiosperm phylogeny is the foundation of studies of gene function and phenotypic evolution, divergence time estimation and biogeography. The relationship of the five divergent groups of the Mesangiospermae (~99.95% of extant angiosperms) remains uncertain, with multiple hypotheses reported in the literature. Here transcriptome data sets are obtained from 26 species lacking sequenced genomes, representing each of the five groups: eudicots, monocots, magnoliids, Chloranthaceae and Ceratophyllaceae. Phylogenetic analyses using 59 carefully selected low-copy nuclear genes resulted in highly supported relationships: sisterhood of eudicots and a clade containing Chloranthaceae and Ceratophyllaceae, with magnoliids being the next sister group, followed by monocots. Our topology allows a re-examination of the evolutionary patterns of 110 morphological characters. The molecular clock estimates of Mesangiospermae diversification during the late to middle Jurassic correspond well to the origins of some insects, which may have been a factor facilitating early angiosperm radiation. PMID:25249442

  11. Resolution of the Gross-Pitaevskii equation with the imaginary-time method on a Lagrange mesh.

    PubMed

    Baye, D; Sparenberg, J-M

    2010-11-01

    The Lagrange-mesh method is an approximate variational calculation which has the simplicity of a mesh calculation. Combined with the imaginary-time method, it is applied to the iterative resolution of the Gross-Pitaevskii equation. Two variants of a fourth-order factorization of the exponential of the Hamiltonian and two types of mesh (Lagrange-Hermite and Lagrange-sinc) are employed and compared. The accuracy is checked with the help of these comparisons and of the virial theorem. The Lagrange-Hermite mesh provides very accurate results with short computing times for values of the dimensionless parameter of the nonlinear term up to 10⁴. For higher values up to 10⁷, the Lagrange-sinc mesh is more efficient. Examples are given for anisotropic and nonseparable trapping potentials.

  12. Molecular Differentiation of Schistosoma japonicum and Schistosoma mekongi by Real-Time PCR with High Resolution Melting Analysis

    PubMed Central

    Kongklieng, Amornmas; Kaewkong, Worasak; Intapan, Pewpan M.; Sanpool, Oranuch; Janwan, Penchom; Thanchomnang, Tongjit; Lulitanond, Viraphong; Sri-Aroon, Pusadee; Limpanont, Yanin

    2013-01-01

    Human schistosomiasis caused by Schistosoma japonicum and Schistosoma mekongi is a chronic and debilitating helminthic disease still prevalent in several countries of Asia. Due to morphological similarities of cercariae and eggs of these 2 species, microscopic differentiation is difficult. High resolution melting (HRM) real-time PCR is developed as an alternative tool for the detection and differentiation of these 2 species. A primer pair was designed for targeting the 18S ribosomal RNA gene to generate PCR products of 156 base pairs for both species. The melting points of S. japonicum and S. mekongi PCR products were 84.5±0.07℃ and 85.7±0.07℃, respectively. The method permits amplification from a single cercaria or an egg. The HRM real-time PCR is a rapid and simple tool for differentiation of S. japonicum and S. mekongi in the intermediate and final hosts. PMID:24516269

  13. Resolution of the Gross-Pitaevskii equation with the imaginary-time method on a Lagrange mesh.

    PubMed

    Baye, D; Sparenberg, J-M

    2010-11-01

    The Lagrange-mesh method is an approximate variational calculation which has the simplicity of a mesh calculation. Combined with the imaginary-time method, it is applied to the iterative resolution of the Gross-Pitaevskii equation. Two variants of a fourth-order factorization of the exponential of the Hamiltonian and two types of mesh (Lagrange-Hermite and Lagrange-sinc) are employed and compared. The accuracy is checked with the help of these comparisons and of the virial theorem. The Lagrange-Hermite mesh provides very accurate results with short computing times for values of the dimensionless parameter of the nonlinear term up to 10⁴. For higher values up to 10⁷, the Lagrange-sinc mesh is more efficient. Examples are given for anisotropic and nonseparable trapping potentials. PMID:21230613

  14. Sampling theory for asynoptic satellite observations. I Space-time spectra, resolution, and aliasing. II - Fast Fourier synoptic mapping

    NASA Technical Reports Server (NTRS)

    Salby, M. L.

    1982-01-01

    An evaluation of the information content of asynoptic data taken in the form of nadir sonde and limb scan observations is presented, and a one-to-one correspondence is established between the alias-free data and twice-daily synoptic maps. Attention is given to space and time limitations of sampling and the orbital geometry is discussed. The sampling pattern is demonstrated to determine unique space-time spectra at all wavenumbers and frequencies. Spectral resolution and aliasing are explored, while restrictions on sampling and information content are defined. It is noted that irregular sampling at high latitudes produces spurious contamination effects. An Asynoptic Sampling Theorem is thereby formulated, as is a Synoptic Retrieval Theorem, in the second part of the article. In the latter, a procedure is developed for retrieving the unique correspondence between the asymptotic data and the synoptic maps. Applications examples are provided using data from the Nimbus-6 satellite.

  15. Time-Resolved Molecular Characterization of Limonene/Ozone Aerosol using High-Resolution Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Bateman, Adam P.; Nizkorodov, Serguei; Laskin, Julia; Laskin, Alexander

    2009-09-09

    Molecular composition of limonene/O3 secondary organic aerosol (SOA) was investigated using high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) as a function of reaction time. SOA was generated by ozonation of D-limonene in a reaction chamber and sampled at different time intervals using a cascade impactor. The SOA samples were extracted into acetonitrile and analyzed using a HR-ESI-MS instrument with a resolving power of 100,000 (m/Δm). The resulting mass spectra provided detailed information about the extent of oxidation inferred from the O:C ratios, double bond equivalency (DBE) factors, and aromaticity indexes (AI) in hundreds of identified individual SOA species.

  16. Automatic Detection of Clouds and Shadows Using High Resolution Satellite Image Time Series

    NASA Astrophysics Data System (ADS)

    Champion, Nicolas

    2016-06-01

    Detecting clouds and their shadows is one of the primaries steps to perform when processing satellite images because they may alter the quality of some products such as large-area orthomosaics. The main goal of this paper is to present the automatic method developed at IGN-France for detecting clouds and shadows in a sequence of satellite images. In our work, surface reflectance orthoimages are used. They were processed from initial satellite images using a dedicated software. The cloud detection step consists of a region-growing algorithm. Seeds are firstly extracted. For that purpose and for each input ortho-image to process, we select the other ortho-images of the sequence that intersect it. The pixels of the input ortho-image are secondly labelled seeds if the difference of reflectance (in the blue channel) with overlapping ortho-images is bigger than a given threshold. Clouds are eventually delineated using a region-growing method based on a radiometric and homogeneity criterion. Regarding the shadow detection, our method is based on the idea that a shadow pixel is darker when comparing to the other images of the time series. The detection is basically composed of three steps. Firstly, we compute a synthetic ortho-image covering the whole study area. Its pixels have a value corresponding to the median value of all input reflectance ortho-images intersecting at that pixel location. Secondly, for each input ortho-image, a pixel is labelled shadows if the difference of reflectance (in the NIR channel) with the synthetic ortho-image is below a given threshold. Eventually, an optional region-growing step may be used to refine the results. Note that pixels labelled clouds during the cloud detection are not used for computing the median value in the first step; additionally, the NIR input data channel is used to perform the shadow detection, because it appeared to better discriminate shadow pixels. The method was tested on times series of Landsat 8 and Pl

  17. Estimating rheological properties of lava flows using high-resolution time lapse imaging

    NASA Astrophysics Data System (ADS)

    James, M. R.; Applegarth, L. J.; Pinkerton, H.; Fryer, T.

    2011-12-01

    During effusive eruptions, property and infrastructure can be threatened by lava flow inundation. In order to maximise the effectiveness of the response to such an event, it is necessary to be able to reliably forecast the area that will be affected. One of the major controls on the advance of a lava flow is its rheology, which is spatially and temporally variable, and depends on many underlying factors. Estimating the rheological properties of a lava flow, and the change in these over space and time is therefore of the utmost importance. Here we report estimates of rheological properties made from geometric and velocity measurements on integrated topographic and image data using the method of Ellis et al. (2004) (Ellis B, Wilson L & Pinkerton H (2004) Estimating the rheology of basaltic lava flows. Lunar & Planetary Science XXXV Abst. 1550). These are then compared to the viscosity predicted from composition and temperature by the GRD model (Giordano D, Russell JK, & Dingwell DB (2008) Viscosity of Magmatic Liquids: A Model. Earth & Planetary Science Letters, 271, 123-134). During the 13 May 2008 - 6 July 2009 eruption of Mt Etna, Sicily, lava flows were emplaced into the Valle del Bove, reaching a maximum length of >6 km. Towards the end of the eruption, multiple channelized aa flows were active simultaneously, reaching tens to hundreds of metres in length. Flow lifetimes were of the order hours to days. In the last month of the eruption, we installed a Canon EOS 450D camera at Pizzi Deneri, on the north side of the Valle del Bove, to collect visible images at 15-minute intervals. On one day, topographic data (using a Riegl LPM-321 terrestrial laser scanner) and thermal images (using a FLIR Thermacam S40) were also collected from this location. The fronts of some of the larger flows were tracked through the time lapse image sequence. Using knowledge of the camera imaging geometry, the pixel tracks were reprojected onto the topographic surface to determine flow

  18. DETECTORS AND EXPERIMENTAL METHODS: Effect of the integrated time of the induced current signal on the position resolution of the RPC detector

    NASA Astrophysics Data System (ADS)

    Ye, Jin; Yue, Qian; Li, Yuan-Jing; Cheng, Jian-Ping; Li, Jin; Wang, Yi

    2009-08-01

    A prototype RPC with position resolution less than 1 mm has been produced and studied. Based on this RPC detector, the effect of the width of the integrated FADC time window on the position resolution of a RPC has been studied experimentally and theoretically. The results of theoretical calculation and experimental measurement have shown good agreement.

  19. Modern U-Pb chronometry of meteorites: advancing to higher time resolution reveals new problems

    USGS Publications Warehouse

    Amelin, Y.; Connelly, J.; Zartman, R.E.; Chen, J.-H.; Gopel, C.; Neymark, L.A.

    2009-01-01

    In this paper, we evaluate the factors that influence the accuracy of lead (Pb)-isotopic ages of meteorites, and may possibly be responsible for inconsistencies between Pb-isotopic and extinct nuclide timescales of the early Solar System: instrumental mass fractionation and other possible analytical sources of error, presence of more than one component of non-radiogenic Pb, migration of ancient radiogenic Pb by diffusion and other mechanisms, possible heterogeneity of the isotopic composition of uranium (U), uncertainties in the decay constants of uranium isotopes, possible presence of "freshly synthesized" actinides with short half-life (e.g. 234U) in the early Solar System, possible initial disequilibrium in the uranium decay chains, and potential fractionation of radiogenic Pb isotopes and U isotopes caused by alpha-recoil and subsequent laboratory treatment. We review the use of 232Th/238U values to assist in making accurate interpretations of the U-Pb ages of meteorite components. We discuss recently published U-Pb dates of calcium-aluminum-rich inclusions (CAIs), and their apparent disagreement with the extinct nuclide dates, in the context of capability and common pitfalls in modern meteorite chronology. Finally, we discuss the requirements of meteorites that are intended to be used as the reference points in building a consistent time scale of the early Solar System, based on the combined use of the U-Pb system and extinct nuclide chronometers.

  20. Construction and performance of a photobleaching recovery apparatus with microsecond time resolution.

    PubMed

    Kao, H P; Verkman, A S

    1996-03-01

    A fluorescence recovery after photobleaching (FRAP) apparatus was constructed to measure sub-millisecond fluorescence recovery processes in living cells. The photobleaching pulse and probe beams were generated by modulating the intensity of a continuous wave Argon laser (4 W) by two acousto-optic modulators in series. The maximum intensity modulation was > 10(6):1 with a rise time of < 1 microsecond and a minimum pulse width of 6 microseconds. Fluorescence was detected by a photomultiplier, amplified by a transimpedance amplifier, and digitized at 1 MHz. During the photobleaching pulse, the photomultiplier gain was reduced by ca. 1500-fold by switching the second dynode voltage ca. 100 V negative with respect to the cathode voltage by computer control of two bidirectional Mosfet optoisolators. The switching circuit produced a optoisolators. The switching circuit produced a transient anode current (t approximately 15 microseconds) which was subtracted for measurement of recoveries of < 50-100 microseconds. The apparatus was coupled to an inverted microscope for measurement of fluorescence by epi-illumination or total internal reflection. Instrument performance was evaluated by measurement of the rapid fluorescence recoveries of fluorescein and fluorescein-dextrans in solutions and living cells.

  1. Real-time mosaic - rapid response, high resolution imaging from space

    NASA Astrophysics Data System (ADS)

    da Silva Curiel, A.; Wazni, M.; Boland, Lee; Davies, Phil; Eves, Stuart; Sun, Wei; Sweeting, Martin

    2004-11-01

    An imaging constellation mission is proposed to provide near-continuous surveillance of regional activity. By introducing a multiple plane constellation of small Earth Observation satellites, it is possible to monitor selected parts of the entire globe several times during daylight. Using off-the-shelf microsatellites ensures the program is responsive in the deployment phase as well as in the operational phase. The paper describes the basic Disaster Monitoring Constellation programme as has been implemented, which already delivers daily imagery. It also describes the system trades of the regional imaging constellations, and outlines the scope of the performance that could be obtained from such a system. A cost model illustrates that the balance between launch and space segment costs must be reached by considering suitable replacement strategies, and that the system is highly sensitive to requirement creep. Finally, it is shown that the use of cost effective, small satellites leads to solutions previously thought to be out of reach of Earth Science and Government customers.

  2. High Time Resolution Measurements of Methane Fluxes From Enteric Fermentation in Cattle Rumen

    NASA Astrophysics Data System (ADS)

    Floerchinger, C. R.; Herndon, S.; Fortner, E.; Roscioli, J. R.; Kolb, C. E.; Knighton, W. B.; Molina, L. T.; Zavala, M.; Castelán, O.; Ku Vera, J.; Castillo, E.

    2013-12-01

    Methane accounts for roughly 20% of the global radiative climate forcing in the last two and a half centuries. Methane emissions arise from a number of anthropogenic and biogenic sources. In some areas enteric fermentation in livestock produces over 90% of agricultural methane. In the spring of 2013, as a part of the Short Lived Climate Forcer-Mexico field campaign, the Aerodyne Mobile Laboratory in partnership with the Molina Center for the Environment studied methane production associated with enteric fermentation in the rumen of cattle. A variety of different breeds and stocks being raised in two agricultural and veterinary research facilities located in different areas of Mexico were examined. Methane fluxes were quantified using two methods: 1) an atmospherically stable gaseous tracer release was collocated with small herds in a pasture, allowing tracer ratio flux measurements; 2) respiratory CO2 was measured in tandem with methane in the breath of individual animals allowing methane production to be related to metabolism. The use of an extensive suite of very high time response instruments allows for differentiation of individual methane producing rumination events and respiratory CO2 from possible background interferences. The results of these studies will be presented and compared to data from traditional chamber experiments.

  3. A field assessment of high resolution aquifer characterization: Coupling of hydraulic travel time and hydraulic attenuation tomography

    NASA Astrophysics Data System (ADS)

    Brauchler, R.; Hu, R.; Dietrich, P.; Sauter, M.

    2009-12-01

    Knowledge about the spatial variations in hydraulic properties plays an important role controlling solute movement in saturated flow systems. Traditional hydrogeological approaches appear to have difficulties providing high resolution parameter estimates. Thus, we have decided to develop an approach coupling hydraulic travel time and attenuation tomography. Hydraulic travel time tomography is based on the transformation of the transient ground water flow equation into the eikonal equation using an asymptotic approach. The eikonal equation can be solved with ray tracing techniques, which allow the calculation of pressure propagation along trajectories. As the travel time of a hydraulic signal depends on the diffusivity of the investigated media, it is difficult to separate it into its components hydraulic conductivity and specific storage. In order to overcome this problem we perform next to the travel time inversion an inversion which is based on the relationship between attenuation of a hydraulic signal travelling between source and receiver, and the specific storage of the investigated media. Both inversion techniques are based on ray tracing, which allows the inversion of large data sets in a short time on a common PC. The attenuation and travel time based inversion approaches are naturally complementary: Hydraulic travel times are determined by the hydraulic diffusivity, a combination of hydraulic conductivity and specific storage, whereas the attenuation is determined solely by specific storage. Thus, combining these two approaches will allow the independent identification of hydraulic conductivity and specific storage. The potential of our hydraulic tomographical approach was investigated at a well-characterized sand and gravel aquifer located in the Leine River valley near Goettingen, Germany. The data base for the hydraulic inversion consists of 400 pressure cross-hole slug tests performed between five wells in which the positions of the sources (injection

  4. Time course of inflammation resolution in patients with frequent exacerbations of chronic obstructive pulmonary disease

    PubMed Central

    Chang, Chun; Yao, Wanzhen

    2014-01-01

    Background When exacerbation of chronic obstructive pulmonary disease (AECOPD) occurs frequently, patients have high levels of airway and systemic inflammation and a poor quality of life. This study compared the nature and course of systemic and airway inflammation during AECOPD between patients who experienced frequent exacerbations and those with non-frequent exacerbations. Material/Methods Consecutive hospitalized patients with AECOPD were recruited and divided into 2 groups according to the frequency of AECOPD they had experienced in the previous year. Frequent exacerbators (defined as 2 or more AECOPD in the previous year) and non-frequent exacerbators (defined as zero or 1 AECOPD in the previous year). Inflammatory (interleukin 6, interleukin 8, myeloperoxidase, and C-reactive protein) and clinical (dyspnea, COPD assessment test (CAT), and peak expiratory flow) indices were assessed on the day of admission before starting therapy, day 7 of treatment, the day of planned discharge (day 10–14), and 8 weeks after discharge. Results We analyzed data from 135 patients; 78 (57.8%) were non-frequent exacerbators and 57 (42.2%) were frequent exacerbators. In both groups, the inflammatory and clinical indices at day 7, the day of planned discharge (day 10–14), and 8 weeks were significantly improved compared to those at admission. Frequent exacerbators had a smaller reduction in their inflammatory indices and CAT scores between exacerbation onset and all the other time points compared with infrequent exacerbators. Conclusions Frequent exacerbators have a reduced response to treatment of AECOPD in terms of inflammatory indices and quality of life. PMID:24569299

  5. High Time Resolution Studies of X-Ray Bursts: Neutron Star Structure

    NASA Astrophysics Data System (ADS)

    Zhang, William

    1998-04-01

    Galactic low mass X-ray binaries distinguish themselves from the X-Ray pulsars by two characteristics: (1) they emit X-ray bursts due to unstable nuclear burning of accreted matter on the neutron star surface, and (2) they do not appear to emit coherent pulsations, even though they are believed to harbor fast-spinning neutron stars. One of the ``holy grails'' of X-ray astronomy in the 1980's was to measure the spin rates of these neutron stars so as to establish these neutron stars as progenitors of milli-second radio pulsars. Since the launch of the Rossi X-Ray Timing Explorer in 1995, highly coherent flux oscillations, with a Q-value of several hundred, have been observed during the X-ray bursts of several low mass X-ray binaries. All aspects of these oscillations, i.e., coherence, frequency stability from one burst to another for a given binary, their absence and presence at different phases of the bursts, strongly indicate that these oscillations are due to rotation of the neutron star. A very promising interpretation is that they are due to a combination of the neutron star rotation and surface temperature variations during the unstable nuclear burning. Therefore it is quite appropriate to call these neutron stars nuclear powered pulsars. These oscillations offer a unique opportunity to probe the neutron star structure. In this talk I will review the observational status of these oscillations and show how we could use them to study the intrinsic properties of the neutron star (mass, radius, and magnetic field).

  6. Space-time conditional disaggregation of precipitation at high resolution via simulation

    NASA Astrophysics Data System (ADS)

    Bárdossy, András.; Pegram, Geoffrey G. S.

    2016-02-01

    Daily rainfall data are more plentiful and reliable than pluviometer data and are the best data set to start data-repair from, worldwide. Clusters of pluviometers (a term used herein for instruments recording at subdaily intervals) record wet and dry periods in close synchrony and larger and smaller catches tend to be recorded in similar groups, but they have many gaps that require infilling. We present a method of disaggregating daily rainfall to subdaily intervals, contemporaneously infilling gaps in the pluviometers. Then the observed data, together with the infilled and disaggregated values, are interpolated over the intervening space. To achieve this disaggregation, we used a Gaussian copula-based model with time-dependent marginal distributions and censored values representing the dry periods. In addition, we generated stochastically meaningful ensembles of missing or disaggregated values, while constraining each realization to the observed daily total where relevant. This applies to the gaps filled in the pluviometers as well as the disaggregation of the daily totals. Using the disaggregated and infilled subdaily ensembles, we then conditionally spatially simulated historical rainfall in the space between the gauges and pluviometers. The mean of these stochastic realizations was compared to interpolated fields using two other procedures: Rescaled Ordinary Kriging and Rescaled Nearest Neighbors, and found our method to be superior. Where there are daily data, the daily sum constrains the simulation. In the intervening space, in a chosen daily subinterval, there will be an ensemble of values simulated from the observations. We present the results of measurements and validation of the applications to an unusually large amount of data (not just a few convenient samples), and are confident that the methodology is sound and applicable in a variety of geographies.

  7. Design of a wireless sensor network with nanosecond time resolution for mapping of high-energy cosmic ray shower events

    NASA Astrophysics Data System (ADS)

    Frank, Michael P.; Junnarkar, Sachin S.; Fagan, Triesha; O'Neal, Ray H.; Takai, Helio

    2010-04-01

    We describe a low-cost, low-power wireless sensor network we are developing for high time-resolution (ns-scale) characterization of particle showers produced by ultra-high-energy (UHE) cosmic rays, to infer shower direction at sites where hard-wired data connections may be inconvenient to install. The front-end particle detector is a scintillator block monitored by a photomultiplier tube (PMT). We keep the sensor nodes synchronized to within 1 ns using periodic highintensity optical pulses from a light-emitting-diode (LED) overdriven at very high current (~30 A) in short (4 ns) bursts. With minimal optics, this signal is resolvable under free-space transmission in ambient light conditions at multi-meter distances using a high-speed avalanche photodiode (APD) receiver at each node. PMT pulse waveforms are digitized relative to this precise time reference on a Field Programmable Gate Array (FPGA) using a Time-over-Threshold (ToT)/Time-to-Digital Converter (TDC) digitizer developed at BNL. A central server receives timestamped, digitized PMT pulse waveforms from the sensor nodes via Wi-Fi and performs real-time data visualization & analysis. Total cost per sensor node is a few thousand dollars, with total power consumption per sensor node under 1 Watt, suitable for, e.g., solar-powered installations at remote field locations.

  8. 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.

  9. Optical tomography of human skin with subcellular spatial and picosecond time resolution using intense near infrared femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Koenig, Karsten; Wollina, Uwe; Riemann, Iris; Peukert, Christiane; Halbhuber, Karl-Juergen; Konrad, Helga; Fischer, Peter; Fuenfstueck, Veronika; Fischer, Tobias W.; Elsner, Peter

    2002-06-01

    We describe the novel high resolution imaging tool DermaInspect 100 for non-invasive diagnosis of dermatological disorders based on multiphoton autofluorescence imaging (MAI)and second harmonic generation. Femtosecond laser pulses in the spectral range of 750 nm to 850 nm have been used to image in vitro and in vivo human skin with subcellular spatial and picosecond temporal resolution. The non-linear induced autofluorescence originates mainly from naturally endogenous fluorophores/protein structures like NAD(P)H, flavins, keratin, collagen, elastin, porphyrins and melanin. Second harmonic generation was observed in the stratum corneum and in the dermis. The system with a wavelength-tunable compact 80 MHz Ti:sapphire laser, a scan module with galvo scan mirrors, piezoelectric objective positioner, fast photon detector and time-resolved single photon counting unit was used to perform optical sectioning and 3D autofluorescence lifetime imaging (t-mapping). In addition, a modified femtosecond laser scanning microscope was involved in autofluorescence measurements. Tissues of patients with psoriasis, nevi, dermatitis, basalioma and melanoma have been investigated. Individual cells and skin structures could be clearly visualized. Intracellular components and connective tissue structures could be further characterized by tuning the excitation wavelength in the range of 750 nm to 850 nm and by calculation of mean fluorescence lifetimes per pixel and of particular regions of interest. The novel non-invasive imaging system provides 4D (x,y,z,t) optical biopsies with subcellular resolution and offers the possibility to introduce a further optical diagnostic method in dermatology.

  10. High-Resolution Mapping of Flows in the Solar Interior: Fully Consistent OLA Inversion of Helioseismic Travel Times

    NASA Astrophysics Data System (ADS)

    Jackiewicz, J.; Gizon, L.; Birch, A. C.

    2008-09-01

    To recover the flow information encoded in travel-time data of time distance helioseismology, accurate forward modeling and a robust inversion of the travel times are required. We accomplish this using three-dimensional finite-frequency travel-time sensitivity kernels for flows along with a (2+1)-dimensional (2+1D) optimally localized averaging (OLA) inversion scheme. Travel times are measured by ridge filtering MDI full-disk Doppler data and the corresponding Born sensitivity kernels are computed for these particular travel times. We also utilize the full noise-covariance properties of the travel times, which allow us to accurately estimate the errors for all inversions. The whole procedure is thus fully consistent. Because of ridge filtering, the kernel functions separate in the horizontal and vertical directions, motivating our choice of a 2+1D inversion implementation. The inversion procedure also minimizes cross-talk effects among the three flow components, and the averaging kernels resulting from the inversion show very small amounts of cross-talk. We obtain three-dimensional maps of vector solar flows in the quiet Sun at horizontal spatial resolutions of 7-10 Mm using generally 24 hours of data. For all of the flow maps we provide averaging kernels and the noise estimates. We present examples to test the inferred flows, such as a comparison with Doppler data, in which we find a correlation of 0.9. We also present results for quiet-Sun supergranular flows at different depths in the upper convection zone. Our estimation of the vertical velocity shows good qualitative agreement with the horizontal vector flows. We also show vertical flows measured solely from f-mode travel times. In addition, we demonstrate how to directly invert for the horizontal divergence and flow vorticity. Finally we study inferred flow-map correlations at different depths and find a rapid decrease in this correlation with depth, consistent with other recent local helioseismic analyses.

  11. High resolution time-of-flight mass analysis of the entire range of intact singly-charged proteins.

    PubMed

    Lee, Jeonghoon; Chen, Huijuan; Liu, Tiancheng; Berkman, Clifford E; Reilly, Peter T A

    2011-12-15

    The proof of principle for high-resolution analysis of intact singly charged proteins of any size is presented. Singly charged protein ions were produced by electrospray ionization followed by surface-induced charge reduction at atmospheric pressure. The inlet and trapping system "stops" the forward momentum of the protein ions over a very broad range to be captured by the digitally produced electric fields of a large radius linear ion trap whereupon they are moved into a smaller radius linear ion trap and collected and concentrated in front of its exit end-cap electrode using digital waveform manipulation. The protein ions are then ejected on demand from the end of the small radius linear quadrupole in a tightly collimated ion beam with an instrumentally defined kinetic energy into the acceleration region of an orthogonal acceleration reflectron time-of-flight mass analyzer where their flight times were measured and detected with a Photonis BiPolar TOF detector. We present results that clearly prove that massive singly charged ions can yield high-resolution mass spectra with very low chemical noise and without loss of sensitivity with increasing mass across the entire spectrum. Analysis of noncovalently bound protein complexes was demonstrated with streptavidin-Cy5 bound with a biotinylated peptide mimic. Our results suggest proteins across the entire range can be directly quantified using our mass analysis technique. We present evidence that solvent molecules noncovalently adduct onto the proteins while yielding consistent flight time distributions. Finally, we provide a look into future that will result from the ability to rapidly measure and quantify protein distributions.

  12. A Spatio-temporal disaggregation method to derive time series of Normalized Difference Vegetation Index and Land Surface Temperature at fine spatial resolution

    NASA Astrophysics Data System (ADS)

    Bindhu, V. M.; Narasimhan, B.

    2014-12-01

    Estimation of evapotranspiration (ET) from remote sensing based energy balance models have evolved as a promising tool in the field of water resources management. Performance of energy balance models and reliability of ET estimates is decided by the availability of remote sensing data at high spatial and temporal resolutions. However huge tradeoff in the spatial and temporal resolution of satellite images act as major constraints in deriving ET at fine spatial and temporal resolution using remote sensing based energy balance models. Hence a need exists to derive finer resolution data from the available coarse resolution imagery, which could be applied to deliver ET estimates at scales to the range of individual fields. The current study employed a spatio-temporal disaggregation method to derive fine spatial resolution (60 m) images of NDVI by integrating the information in terms of crop phenology derived from time series of MODIS NDVI composites with fine resolution NDVI derived from a single AWiFS data acquired during the season. The disaggregated images of NDVI at fine resolution were used to disaggregate MODIS LST data at 960 m resolution to the scale of Landsat LST data at 60 m resolution. The robustness of the algorithm was verified by comparison of the disaggregated NDVI and LST with concurrent NDVI and LST images derived from Landsat ETM+. The results showed that disaggregated NDVI and LST images compared well with the concurrent NDVI and LST derived from ETM+ at fine resolution with a high Nash Sutcliffe Efficiency and low Root Mean Square Error. The proposed disaggregation method proves promising in generating time series of ET at fine resolution for effective water management.

  13. The real-time, high-resolution x-ray video microscopy of solidification in aluminum alloys

    NASA Astrophysics Data System (ADS)

    Arnberg, Lars; Mathiesen, Ragnvald H.

    2007-08-01

    The directional solidification of thin alloy sheets in a Bridgman furnace has been studied by x-radiography using high-brilliance synchrotron x-radiation in combination with a low-noise, fast-readout camera. Spatial resolutions down to 1.5 μm and a temporal resolution of about 0.15 s have permitted real-time video microscopy of microstructural evolution during columnar and equiaxed dendrite growth and eutectic and monotectic growth. The technique has also allowed for direct observations of important solidification phenomena such as dendrite fragmentation and porosity formation, primarily in aluminium alloys. As a result, insights have been gained into mechanisms of dendrite fragmentation, criteria for dendrite tip kinetics and interface stability during transient growth, and microstructure formation mechanisms during monotectic solidification. The results are expected to be important for validation of dendrite growth models. This paper presents a review of the technique as well as examples of images obtained during solidification of aluminum alloys.

  14. Water Quality Data at High Time and Space Resolution in the Field : Expanding Spectrophotometer Capabilities with Arduino Driven Autosamplers

    NASA Astrophysics Data System (ADS)

    Birgand, F.; Maxwell, B.; Aveni-Deforge, K.; Etheridge, R.

    2014-12-01

    Availability of continuous hydrological data (e.g. flow rates, rainfall, etc.) for over a century has shaped our current understanding of the hydrological cycle. Until now, there has been no equivalence for water quality. Optics based systems now open the possibility to obtain data at a temporal resolution in par with that commonly used in quantitative hydrology (e.g. 15 min - 1 hr). We show that absorbance measured in the field using spectrophotometers can be statistically correlated with light- and none- absorbing constituents in the water. Water quality rating curves for 6-12 parameters can be derived as such using a single spectrophotometer, opening access to continuous water quality data for many parameters at a time. We then show that attaching such probe in the field with multiplexed pumping systems driven by Arduinos can expand the high temporal resolution capabilities to space as our systems can sample up to 12 different water sources located within 15 m of the water quality probe.

  15. High harmonic generation based time resolved ARPES at 30 eV with 50 meV energy resolution

    NASA Astrophysics Data System (ADS)

    Rohwer, Timm; Sie, Edbert J.; Mahmood, Fahad; Gedik, Nuh

    Angle-resolved photoelectron spectroscopy (ARPES) has emerged as a leading technique in identifying equilibrium properties of complex electronic systems as well as their correlated dynamics. By using femtosecond high harmonic generation (HHG) pulses, this technique can be extended to monitor ultrafast changes in the electronic structure in response to an optical excitation. However, the broad bandwidth of the HHG pulses has been a major experimental limitation. In this contribution, we combine the HHG source with an off-axis Czerny-Turner XUV monochromator and a three-dimensional ``ARTOF'' photoelectron detector to achieve an unrivaled overall energy resolution of 50 meV in multiple harmonic energies. Moreover, the use of a stack of different gratings enables us to fine control both the photon energy and time vs. energy resolution to its particular needs. The performance of our setup is demonstrated by studies on the transition metal dichalcogenide IrTe2 which undergoes a first-order structural transition and accompanied reconstruction of the band structure upon cooling without the characteristic opening of an energy gap.

  16. Detector system with high time resolution for the continuous measurement of spectra in the vacuum ultraviolet wavelength range

    NASA Astrophysics Data System (ADS)

    Biel, W.; Bertschinger, G.

    2004-07-01

    A new detector system with high time resolution (1 ms) has been developed and applied for the continuous measurement of spectra in the vacuum ultraviolet (VUV) and extreme ultraviolet (EUV) wavelength region at the fusion plasma experiment Torus Experiment for Technology-Oriented Research (TEXTOR). The system consists of an open multichannel-plate (MCP) detector with subsequent first generation (Gen I) light amplifier and a camera head which is based on a linear photodiode array with 1024 elements (pixels). The camera head provides the output signals of the individual pixels sequentially as an analog voltage with a full spectra rate of 1000 per second, which are measured using a PC-based data acquisition system. Three vacuum spectrometers operating in the VUV/EUV region (10-130 nm) have been equipped with the new system and a successful campaign of measurements from about 4000 discharges at TEXTOR has been performed. Spectra are recorded with a usable linear dynamic range of 10 bit and a wavelength resolution corresponding to a width of 3-4 pixels.

  17. Timing Characteristics of Large Area Picosecond Photodetectors

    SciTech Connect

    Adams, Bernhard W.; Elagin, Andrey L.; Frisch, H.; Obaid, Razib; Oberla, E; Vostrikov, Alexander; Wagner, Robert G.; Wang, Jingbo; Wetstein, Matthew J.; Northrop, R

    2015-09-21

    The LAPPD Collaboration was formed to develop ultralast large-area imaging photodetectors based on new methods for fabricating microchannel plates (MCPs). In this paper we characterize the time response using a pulsed, sub picosecond laser. We observe single photoelectron time resolutions of a 20 cm x 20 cm MCP consistently below 70 ps, spatial resolutions of roughly 500 pm, and median gains higher than 10(7). The RMS measured at one particular point on an LAPPD detector is 58 ps, with in of 47 ps. The differential time resolution between the signal reaching the two ends of the delay line anode is measured to be 5.1 ps for large signals, with an asymptotic limit falling below 2 ps as noise-over-signal approaches zero.

  18. Timing characteristics of Large Area Picosecond Photodetectors

    NASA Astrophysics Data System (ADS)

    Adams, B. W.; Elagin, A.; Frisch, H. J.; Obaid, R.; Oberla, E.; Vostrikov, A.; Wagner, R. G.; Wang, J.; Wetstein, M.

    2015-09-01

    The LAPPD Collaboration was formed to develop ultrafast large-area imaging photodetectors based on new methods for fabricating microchannel plates (MCPs). In this paper we characterize the time response using a pulsed, sub-picosecond laser. We observe single-photoelectron time resolutions of a 20 cm × 20 cm MCP consistently below 70 ps, spatial resolutions of roughly 500 μm, and median gains higher than 107. The RMS measured at one particular point on an LAPPD detector is 58 ps, with ± 1σ of 47 ps. The differential time resolution between the signal reaching the two ends of the delay line anode is measured to be 5.1 ps for large signals, with an asymptotic limit falling below 2 ps as noise-over-signal approaches zero.

  19. Relativistic electron flux comparisons at low and high altitudes with fast time resolution and broad spatial coverage

    NASA Technical Reports Server (NTRS)

    Imhof, W. L.; Gaines, E. E.; Mcglennon, J. P.; Baker, D. N.; Reeves, G. D.; Belian, R. D.

    1994-01-01

    Analyses are presented for the first high-time resolution multisatellite study of the spatial and temporal characteristics of a relativistic electron enhancement event with a rapid onset. Measurements of MeV electrons were made from two low-altitude polar orbiting satellites and three spacecraft at synchronous altitude. The electron fluxes observed by the low-altitude satellites include precipitating electrons in both the bounce and drift loss cones as well as electrons that are stably trapped, whereas the observations at geosynchronous altitude are dominated by the trapped population. The fluxes of greater than 1 MeV electrons at low-satellite altitude over a wide range of L shells tracked very well the fluxes greater than 0.93 MeV at synchronous altitude.

  20. Invited article: micron resolution spatially resolved measurement of heat capacity using dual-frequency time-domain thermoreflectance.

    PubMed

    Wei, Changdong; Zheng, Xuan; Cahill, David G; Zhao, Ji-Cheng

    2013-07-01

    A pump-probe photothermal technique - dual-frequency time-domain thermoreflectance - was developed for measuring heat capacity with a spatial resolution on the order of 10 μm. The method was validated by measuring several common materials with known heat capacity. Rapid measurement of composition-phase-property relationships was demonstrated on Ti-TiSi2 and Ni-Zr diffusion couples; experimental values of heat capacity of the intermetallic compounds in these diffusion couples were compared with literature values and CALPHAD (CALculation of PHAse Diagram) calculations. The combination of this method and diffusion multiples provides an efficient way to generate thermodynamic data for CALPHAD modeling and database construction. The limitation of this method in measuring low thermal diffusivity materials is also discussed.