Science.gov

Sample records for rms time resolution

  1. 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.

  2. Multichannel FPGA based MVT system for high precision time (20 ps RMS) and charge measurement

    NASA Astrophysics Data System (ADS)

    Pałka, M.; Strzempek, P.; Korcyl, G.; Bednarski, T.; Niedźwiecki, Sz.; Białas, P.; Czerwiński, E.; Dulski, K.; Gajos, A.; Głowacz, B.; Gorgol, M.; Jasińska, B.; Kamińska, D.; Kajetanowicz, M.; Kowalski, P.; Kozik, T.; Krzemień, W.; Kubicz, E.; Mohhamed, M.; Raczyński, L.; Rudy, Z.; Rundel, O.; Salabura, P.; Sharma, N. G.; Silarski, M.; Smyrski, J.; Strzelecki, A.; Wieczorek, A.; Wiślicki, W.; Zieliński, M.; Zgardzińska, B.; Moskal, P.

    2017-08-01

    In this article it is presented an FPGA based Multi-Voltage Threshold (MVT) system which allows of sampling fast signals (1-2 ns rising and falling edge) in both voltage and time domain. It is possible to achieve a precision of time measurement of 20 ps RMS and reconstruct charge of signals, using a simple approach, with deviation from real value smaller than 10%. Utilization of the differential inputs of an FPGA chip as comparators together with an implementation of a TDC inside an FPGA allowed us to achieve a compact multi-channel system characterized by low power consumption and low production costs. This paper describes realization and functioning of the system comprising 192-channel TDC board and a four mezzanine cards which split incoming signals and discriminate them. The boards have been used to validate a newly developed Time-of-Flight Positron Emission Tomography system based on plastic scintillators. The achieved full system time resolution of σ(TOF) ≈ 68 ps is by factor of two better with respect to the current TOF-PET systems.

  3. Probabilistic reasoning over seismic RMS time series: volcano monitoring through HMMs and SAX technique

    NASA Astrophysics Data System (ADS)

    Aliotta, M. A.; Cassisi, C.; Prestifilippo, M.; Cannata, A.; Montalto, P.; Patanè, D.

    2014-12-01

    During the last years, volcanic activity at Mt. Etna was often characterized by cyclic occurrences of fountains. In the period between January 2011 and June 2013, 38 episodes of lava fountains has been observed. Automatic recognition of the volcano's states related to lava fountain episodes (Quiet, Pre-Fountaining, Fountaining, Post-Fountaining) is very useful for monitoring purposes. We discovered that such states are strongly related to the trend of RMS (Root Mean Square) of the seismic signal recorded in the summit area. In the framework of the project PON SIGMA (Integrated Cloud-Sensor System for Advanced Multirisk Management) work, we tried to model the system generating its sampled values (assuming to be a Markov process and assuming that RMS time series is a stochastic process), by using Hidden Markov models (HMMs), that are a powerful tool for modeling any time-varying series. HMMs analysis seeks to discover the sequence of hidden states from the observed emissions. In our framework, observed emissions are characters generated by SAX (Symbolic Aggregate approXimation) technique. SAX is able to map RMS time series values with discrete literal emissions. Our experiments showed how to predict volcano states by means of SAX and HMMs.

  4. Extended RMS

    NASA Image and Video Library

    2005-08-02

    ISS011-E-11416 (2 August 2005) --- A line of thunderstorms form the backdrop for this view of the extended Space Shuttle Discovery’;s remote manipulator system (RMS) robotic arm while docked to the International Space Station during the STS-114 mission.

  5. Extended RMS

    NASA Image and Video Library

    2005-07-30

    S114-E-6077 (30 July 2005) --- The blackness of space and Earth’s horizon form the backdrop for this view while Space Shuttle Discovery was docked to the International Space Station during the STS-114 mission. A portion of Discovery’s remote manipulator system (RMS) robotic arm is visible at lower right and a section of the Station’s truss is visible top frame.

  6. A compact system for high precision time measurements ( < 14 ps RMS) and integrated data acquisition for a large number of channels

    NASA Astrophysics Data System (ADS)

    Traxler, M.; Bayer, E.; Kajetanowicz, M.; Korcyl, G.; Maier, L.; Michel, J.; Palka, M.; Ugur, C.

    2011-12-01

    A high precision ( < 14 ps RMS time resolution) and high channel density ( ~ 256 channels) Time to Digital Converter (TDC) module (realized in FPGAs) with integrated DAQ is presented. The data is transported over up to 8 Gigabit-Ethernet or optical links with up to 3 Gb/s. Slow-Control information is transported over the same links. It can be attached directly to the detector, which allows the elimination of long cables and crate systems. The full 256 channel TDCs are expected to use approximately 30 W electrical power. The module size is 20 cm by 23 cm. Power is provided by a galvanically isolated 48 V low noise power supply. AddOn-boards adapt to the special needs of the detector to be read out, e.g. containing Charge to Width (Q2W) FEE for PMT readout.

  7. 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.

  8. 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.

  9. Remote Minehunting System (RMS)

    DTIC Science & Technology

    2015-12-01

    System (RMS) is a mine reconnaissance system designed for the detection, classification, identification, and localization of bottom and moored mines in...and electro-optical identification sensor) in a compact, lightweight, and hydrodynamically stable towed body. The AN/AQS-20 localizes mine -like...objects and provides the operator with a visual image and a contact data list. All mission data is recorded by the Littoral Combat Ship (LCS) for post

  10. Remote Minehunting System (RMS)

    DTIC Science & Technology

    2013-12-01

    Activity BY - Base Year DAMIR - Defense Acquisition Management Information Retrieval Dev Est - Development Estimate DoD - Department of Defense DSN - Defense...Milestones SAR Baseline Dev Est Current APB Development Objective/Threshold Current Estimate Milestone II DEC 1999 DEC 1999 JUN 2000 DEC 1999 OA...updated and will be re-assessed for MS C to align RMS with the LCS MCM MP IOT &E in September 2015. Acronyms and Abbreviations DOT&E - Director

  11. 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.

  12. 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.

  13. 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

  14. High resolution time interval counter

    NASA Technical Reports Server (NTRS)

    Zhang, Victor S.; Davis, Dick D.; Lombardi, Michael A.

    1995-01-01

    In recent years, we have developed two types of high resolution, multi-channel time interval counters. In the NIST two-way time transfer MODEM application, the counter is designed for operating primarily in the interrupt-driven mode, with 3 start channels and 3 stop channels. The intended start and stop signals are 1 PPS, although other frequencies can also be applied to start and stop the count. The time interval counters used in the NIST Frequency Measurement and Analysis System are implemented with 7 start channels and 7 stop channels. Four of the 7 start channels are devoted to the frequencies of 1 MHz, 5 MHz or 10 MHz, while triggering signals to all other start and stop channels can range from 1 PPS to 100 kHz. Time interval interpolation plays a key role in achieving the high resolution time interval measurements for both counters. With a 10 MHz time base, both counters demonstrate a single-shot resolution of better than 40 ps, and a stability of better than 5 x 10(exp -12) (sigma(sub chi)(tau)) after self test of 1000 seconds). The maximum rate of time interval measurements (with no dead time) is 1.0 kHz for the counter used in the MODEM application and is 2.0 kHz for the counter used in the Frequency Measurement and Analysis System. The counters are implemented as plug-in units for an AT-compatible personal computer. This configuration provides an efficient way of using a computer not only to control and operate the counters, but also to store and process measured data.

  15. 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}.

  16. Beam distributions beyond RMS

    NASA Astrophysics Data System (ADS)

    Decker, F.-J.

    1995-05-01

    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 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 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.

  17. Beam distributions beyond RMS

    NASA Astrophysics Data System (ADS)

    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 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 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.

  18. 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.

  19. 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.

  20. A silicon pixel readout ASIC with 100 ps time resolution for the NA62 experiment

    NASA Astrophysics Data System (ADS)

    Dellacasa, G.; Garbolino, S.; Marchetto, F.; Martoiu, S.; Mazza, G.; Rivetti, A.; Wheadon, R.

    2011-01-01

    The silicon tracker of the NA62 experiment requires the measurement of the particles arrival time with a resolution better than 200 ps rms and a spatial resolution of 300 μm. A time measurement technique based on a Time to Amplitude Converter has been implemented in an ASIC in order to prove the possibility to integrate a TDC with resolution better than 200 ps in a pixel cell. Time-walk problem has been addressed with the use of the Constant Fraction Discriminator technique. The ASIC has been designed in a CMOS 0.13 μm technology with single event upset protection of the digital logic.

  1. High time resolutions observations of Cygnus X-3 with EXOSAT

    NASA Astrophysics Data System (ADS)

    Berger, M.; van der Klis, M.

    1994-12-01

    We have studied the fast timing behavior of Cygnus X-3 using the entire EXOSAT ME dataset on this source, consisting of 22 observations that cover a total of 320 000 seconds. This large amount of data allowed us to measure the rapid (greater than 1 Hz) X-ray variability of the source to an unprecedented accuracy of 0.2% fractional rms amplitude. Above 256 Hz, the power of the X-ray count rate fluctuations is significantly below the level predicted from Poisson statistics modified by the known dead time processes in the instrument. We developed an improved empirical method for predicting the Poisson level in EXOSAT ME High Time Resolution 3 (HTR3) and HTR5 data, and use it in our present analysis. None of the four other X-ray sources studied had a weaker noise-component in the region 1-256 Hz as the power spectra of Cygnus X-3. An instrumental effect could therefore not be excluded. If the effect is instrumental, the 99% confidence upper limit on the 1-256 Hz rapid variability of Cygnus X-3 is 0.6% rms. The consequences of these results for previously reported EXOSAT HTR observations are briefly discussed. We compare our results to the predictions of the stellar wind model for Cygnus X-3. Monte Carlo simulations were carried out to investigate the signal-attenuating effect of the wind. For the most likely wind parameters, the intrinsic source variability is found to be either very strong (approximately 60% rms), unlike seen in any other X-ray source at similar luminosity, or to be less than or approximately 12%, which would be consistent with a black hole candidate in the high state, or a low magnetic field neutron star.

  2. The Application of Root Mean Square Electrocardiography (RMS ECG) for the Detection of Acquired and Congenital Long QT Syndrome

    PubMed Central

    Lux, Robert L.; Sower, Christopher Todd; Allen, Nancy; Etheridge, Susan P.; Tristani-Firouzi, Martin; Saarel, Elizabeth V.

    2014-01-01

    Background Precise measurement of the QT interval is often hampered by difficulty determining the end of the low amplitude T wave. Root mean square electrocardiography (RMS ECG) provides a novel alternative measure of ventricular repolarization. Experimental data have shown that the interval between the RMS ECG QRS and T wave peaks (RTPK) closely reflects the mean ventricular action potential duration while the RMS T wave width (TW) tracks the dispersion of repolarization timing. Here, we tested the precision of RMS ECG to assess ventricular repolarization in humans in the setting of drug-induced and congenital Long QT Syndrome (LQTS). Methods RMS ECG signals were derived from high-resolution 24 hour Holter monitor recordings from 68 subjects after receiving placebo and moxifloxacin and from standard 12 lead ECGs obtained in 97 subjects with LQTS and 97 age- and sex-matched controls. RTPK, QTRMS and RMS TW intervals were automatically measured using custom software and compared to traditional QT measures using lead II. Results All measures of repolarization were prolonged during moxifloxacin administration and in LQTS subjects, but the variance of RMS intervals was significantly smaller than traditional lead II measurements. TW was prolonged during moxifloxacin and in subjects with LQT-2, but not LQT-1 or LQT-3. Conclusion These data validate the application of RMS ECG for the detection of drug-induced and congenital LQTS. RMS ECG measurements are more precise than the current standard of care lead II measurements. PMID:24454918

  3. The application of root mean square electrocardiography (RMS ECG) for the detection of acquired and congenital long QT syndrome.

    PubMed

    Lux, Robert L; Sower, Christopher Todd; Allen, Nancy; Etheridge, Susan P; Tristani-Firouzi, Martin; Saarel, Elizabeth V

    2014-01-01

    Precise measurement of the QT interval is often hampered by difficulty determining the end of the low amplitude T wave. Root mean square electrocardiography (RMS ECG) provides a novel alternative measure of ventricular repolarization. Experimental data have shown that the interval between the RMS ECG QRS and T wave peaks (RTPK) closely reflects the mean ventricular action potential duration while the RMS T wave width (TW) tracks the dispersion of repolarization timing. Here, we tested the precision of RMS ECG to assess ventricular repolarization in humans in the setting of drug-induced and congenital Long QT Syndrome (LQTS). RMS ECG signals were derived from high-resolution 24 hour Holter monitor recordings from 68 subjects after receiving placebo and moxifloxacin and from standard 12 lead ECGs obtained in 97 subjects with LQTS and 97 age- and sex-matched controls. RTPK, QTRMS and RMS TW intervals were automatically measured using custom software and compared to traditional QT measures using lead II. All measures of repolarization were prolonged during moxifloxacin administration and in LQTS subjects, but the variance of RMS intervals was significantly smaller than traditional lead II measurements. TW was prolonged during moxifloxacin and in subjects with LQT-2, but not LQT-1 or LQT-3. These data validate the application of RMS ECG for the detection of drug-induced and congenital LQTS. RMS ECG measurements are more precise than the current standard of care lead II measurements.

  4. RMS-1000: A Reconfigurable Mobile System

    NASA Astrophysics Data System (ADS)

    Sturges, James W.

    1990-02-01

    The RMS-1000 Reconfigurable Mobile System is a highly mobile ground station with direct application to the needs of users requiring real-time access to information gathered by airborne reconnaissance platforms. The system combines high-performance computing and image processing workstations with command, control, and communications capabilities in a lightweight self-contained shelter. The RMS-1000 provides a capability for receiving and processing many forms of intelligence data, including imagery. Background information is presented which shows the RMS-1000 as the culmination of over 38 years of tactical ground station development. The motivation for development of the RN/IS-1000 is further discussed in the context of military requirements in a European conflict.

  5. Space-time super-resolution.

    PubMed

    Shechtman, Eli; Caspi, Yaron; Irani, Michal

    2005-04-01

    We propose a method for constructing a video sequence of high space-time resolution by combining information from multiple low-resolution video sequences of the same dynamic scene. Super-resolution is performed simultaneously in time and in space. By "temporal super-resolution," we mean recovering rapid dynamic events that occur faster than regular frame-rate. Such dynamic events are not visible (or else are observed incorrectly) in any of the input sequences, even if these are played in "slow-motion." The spatial and temporal dimensions are very different in nature, yet are interrelated. This leads to interesting visual trade-offs in time and space and to new video applications. These include: 1) treatment of spatial artifacts (e.g., motion-blur) by increasing the temporal resolution and 2) combination of input sequences of different space-time resolutions (e.g., NTSC, PAL, and even high quality still images) to generate a high quality video sequence. We further analyze and compare characteristics of temporal super-resolution to those of spatial super-resolution. These include: How many video cameras are needed to obtain increased resolution? What is the upper bound on resolution improvement via super-resolution? What is the temporal analogue to the spatial "ringing" effect?

  6. Time Resolution of Fast Photomultipliers for Time of Flight PET

    SciTech Connect

    Szczesniak, Tomasz; Iwanowska, Joanna

    2010-01-05

    Time resolution study of 1 inch Photonis XP1020 photomultiplier is reported. The number of photoelectrons, time jitter and time resolution with 4x4x20 mm{sup 3} LSO crystal were measured. All the mentioned PMT properties were measured at five positions on the photocathode.

  7. A method for coincidence timing resolution enhancement

    SciTech Connect

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

    2016-05-15

    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.

  8. 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.

  9. Optimizing the timing resolution of SiPM sensors for use in TOF-PET detectors

    NASA Astrophysics Data System (ADS)

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

    2009-10-01

    We have investigated the timing performance of Hamamatsu Multi-Pixel Photon Counter (MPPC) photosensors in light of their use in time-of-flight (TOF) positron emission tomography detectors. Measurements using picosecond laser pulses show a single photo-electron root-mean-square (RMS) timing resolution down to about 100 ps. In coincidences of 511 keV photons detected with an LYSO crystal coupled to a MPPC and a BaF 2 detector, an optimum FWHM timing resolution of 600 ps was obtained with leading edge time pickoff at the 1-1.5 photo-electron level. By optimizing the LYSO/MPPC coupling, this can be improved by a factor of 2. We further conclude that the use of stored digitized pulses allows great flexibility and efficiency in developing data analysis algorithms.

  10. 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⊙ black hole.

  11. 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.

  12. High Time Resolution Studies with the GBT

    NASA Astrophysics Data System (ADS)

    Lewandowska, Natalia; Lynch, Ryan S.

    2017-01-01

    The detection of neutron stars 49 years ago has created many new and independent branches of research. In 1967, fast rotating neutron stars, or pulsars, became the first objects of this kind to be discovered at radio wavelengths -- more than 30years after their theoretical prediction.In spite of numerous studies throughout the years, the mechanism of the observed radio emission of pulsars is still not understood. Recent technological developments allow observations of pulsars with time resolutions extending into the nanoseconds range, providing a unique insight into the momentary state of a pulsar.Radio giant pulses are known to occur non-periodically in certain phase ranges, exhibit much higher peak flux densities than regular pulses, and to have pulse widths ranging from the micro- to nanoseconds. Their characteristics make them suitable for high time resolution studies. We present the first high time resolution observations of the original millisecond pulsar PSR B1937+21 carried out with the Robert C. Byrd Green Bank Radio Telescope.

  13. 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.

  14. 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

  15. Astronaut Terry J. Hart in training session RMS for STS-2 bldg 29

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Astronaut Terry J. Hart in training session with the Remote Manipulator System (RMS) for STS-2 bldg 29. Views show Truly working at the command console while watching out the windows. Karen Ehlers, an RMS procedures specialist, can be seen at left side of frame while Astronaut Sally Ride waits on right for her time at the RMS.

  16. Advances in coincidence time resolution for PET.

    PubMed

    Cates, Joshua W; Levin, Craig S

    2016-03-21

    Coincidence time resolution (CTR), an important parameter for time-of-flight (TOF) PET performance, is determined mainly by properties of the scintillation crystal and photodetector used. Stable production techniques for LGSO:Ce (Lu1.8Gd0.2SiO5:Ce) with decay times varying from ∼ 30-40 ns have been established over the past decade, and the decay time can be accurately controlled with varying cerium concentration (0.025-0.075 mol%). This material is promising for TOF-PET, as it has similar light output and equivalent stopping power for 511 keV annihilation photons compared to industry standard LSO:Ce and LYSO:Ce, and the decay time is improved by more than 30% with proper Ce concentration. This work investigates the achievable CTR with LGSO:Ce (0.025 mol%) when coupled to new silicon photomultipliers. Crystal element dimension is another important parameter for achieving fast timing. 20 mm length crystal elements achieve higher 511 keV photon detection efficiency, but also introduce higher scintillation photon transit time variance. 3 mm length crystals are not practical for PET, but have reduced scintillation transit time spread. The CTR between pairs of 2.9 × 2.9 × 3 mm(3) and 2.9 × 2.9 × 20 mm(3) LGSO:Ce crystals was measured to be 80 ± 4 and 122 ± 4 ps FWHM, respectively. Measurements of light yield and intrinsic decay time are also presented for a thorough investigation into the timing performance with LGSO:Ce (0.025 mol%).

  17. 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

  18. Generation of real-time mode high-resolution water vapor fields from GPS observations

    NASA Astrophysics Data System (ADS)

    Yu, Chen; Penna, Nigel T.; Li, Zhenhong

    2017-02-01

    Pointwise GPS measurements of tropospheric zenith total delay can be interpolated to provide high-resolution water vapor maps which may be used for correcting synthetic aperture radar images, for numeral weather prediction, and for correcting Network Real-time Kinematic GPS observations. Several previous studies have addressed the importance of the elevation dependency of water vapor, but it is often a challenge to separate elevation-dependent tropospheric delays from turbulent components. In this paper, we present an iterative tropospheric decomposition interpolation model that decouples the elevation and turbulent tropospheric delay components. For a 150 km × 150 km California study region, we estimate real-time mode zenith total delays at 41 GPS stations over 1 year by using the precise point positioning technique and demonstrate that the decoupled interpolation model generates improved high-resolution tropospheric delay maps compared with previous tropospheric turbulence- and elevation-dependent models. Cross validation of the GPS zenith total delays yields an RMS error of 4.6 mm with the decoupled interpolation model, compared with 8.4 mm with the previous model. On converting the GPS zenith wet delays to precipitable water vapor and interpolating to 1 km grid cells across the region, validations with the Moderate Resolution Imaging Spectroradiometer near-IR water vapor product show 1.7 mm RMS differences by using the decoupled model, compared with 2.0 mm for the previous interpolation model. Such results are obtained without differencing the tropospheric delays or water vapor estimates in time or space, while the errors are similar over flat and mountainous terrains, as well as for both inland and coastal areas.

  19. A 7 ke-SD-FWC 1.2 e-RMS Temporal Random Noise 128×256 Time-Resolved CMOS Image Sensor With Two In-Pixel SDs for Biomedical Applications.

    PubMed

    Seo, Min-Woong; Kawahito, Shoji

    2017-09-21

    A large full well capacity (FWC) for wide signal detection range and low temporal random noise for high sensitivity lock-in pixel CMOS image sensor (CIS) embedded with two in-pixel storage diodes (SDs) has been developed and presented in this paper. For fast charge transfer from photodiode to SDs, a lateral electric field charge modulator (LEFM) is used for the developed lock-in pixel. As a result, the time-resolved CIS achieves a very large SD-FWC of approximately 7ke-, low temporal random noise of 1.2e-rms at 20 fps with true correlated double sampling operation and fast intrinsic response less than 500 ps at 635 nm. The proposed imager has an effective pixel array of [Formula: see text] and a pixel size of [Formula: see text]. The sensor chip is fabricated by Dongbu HiTek 1P4M 0.11 [Formula: see text] CIS process.

  20. 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.

  1. 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

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

    NASA Image and Video Library

    1993-12-05

    STS061-07-003 (4 Dec 1993) --- Swiss astronaut Claude Nicollier is pictured at the aft flight deck station he occupied during much of the time on NASA's STS-61 mission aboard the Space Shuttle Endeavour. Among Nicollier's responsibilities were the control of the Remote Manipulator System (RMS) during operations with the Hubble Space Telescope (HST).

  3. 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

  4. 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

  5. Feasibility study of an avalanche photodiode readout for a high resolution PET with nsec time resolution

    SciTech Connect

    Schmelz, C.; Ziegler, S.; Bradbury, S.M.; Holl, I.; Lorenz, E.; Renker, D.

    1995-08-01

    A feasibility study for a high resolution positron emission tomograph, based on 9.5 x 4 x 4 mm{sup 3} LSO crystals viewed by 3 mm diameter avalanche photodiodes, has been carried out. Using a Na{sup 22} source the authors determined a spatial resolution of 2.3 {+-} 0.1 mm, an energy resolution around 15 % and a time resolution of 2.6 nsec. Possible configurations for larger scale tests and a tomograph are given.

  6. Resources Management System (RMS): An Overview.

    DTIC Science & Technology

    1982-12-01

    Intellignece 56, Other Command Intelligence AG: SC, Procurement Operations SAG’S iS, Inspection and resting * 2S, Quality/Reliabilitv Assurance 3R, Supply System...a legal require- ment to pay for goods or services. An expense is a cost of operating an activity, or a cost of doing business . rn RMS this can lead

  7. WSF, unberthing of satellite by RMS arm

    NASA Image and Video Library

    1996-11-22

    STS080-708-065 (19 Nov.-7 Dec. 1996) --- Backdropped against part of Baja California, the Wake Shield Facility (WSF) is about to be re-berthed in the cargo bay of the Earth-orbiting space shuttle Columbia. Columbia's Remote Manipulator System (RMS) was used extensively during operations with the experiment.

  8. RMS arm extended over Earth view

    NASA Image and Video Library

    2005-08-02

    ISS011-E-11414 (2 August 2005) --- A line of thunderstorms form the backdrop for this view of the extended Space Shuttle Discovery’s remote manipulator system (RMS) robotic arm while docked to the International Space Station during the STS-114 mission.

  9. 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.

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

    NASA Image and Video Library

    1993-12-06

    S61-E-018 (6 Dec 1993) --- Astronaut Jeffrey A. Hoffman, anchored to a foot restraint on the end of the Remote Manipulator System (RMS) arm, inserts the new Wide Field/Planetary Camera (WFPC-II) 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 a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

  11. 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.

  12. High time-resolution photodetectors for PET applications

    SciTech Connect

    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.

  13. Florida Peninsula, LDEF Deploy-RMS

    NASA Image and Video Library

    1984-04-13

    41C-36-1618 (7 April 1984) --- The Remote Manipulator System (RMS) arm suspends the giant Long Duration Exposure Facility (LDEF) high above the Gulf of Mexico prior to releasing it into space. Carried into Earth orbit with the STS-41C crew by the Space Shuttle Challenger, LDEF will remain in space until retrieved by a future Shuttle mission, in nine or ten months. Florida and the Bahama Banks are visible near the Earth's horizon in the 70mm frame.

  14. 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.

  15. Avalanche statistics from data with low time resolution.

    PubMed

    LeBlanc, Michael; Nawano, Aya; Wright, Wendelin J; Gu, Xiaojun; Uhl, J T; Dahmen, Karin A

    2016-11-01

    Extracting avalanche distributions from experimental microplasticity data can be hampered by limited time resolution. We compute the effects of low time resolution on avalanche size distributions and give quantitative criteria for diagnosing and circumventing problems associated with low time resolution. We show that traditional analysis of data obtained at low acquisition rates can lead to avalanche size distributions with incorrect power-law exponents or no power-law scaling at all. Furthermore, we demonstrate that it can lead to apparent data collapses with incorrect power-law and cutoff exponents. We propose new methods to analyze low-resolution stress-time series that can recover the size distribution of the underlying avalanches even when the resolution is so low that naive analysis methods give incorrect results. We test these methods on both downsampled simulation data from a simple model and downsampled bulk metallic glass compression data and find that the methods recover the correct critical exponents.

  16. Avalanche statistics from data with low time resolution

    NASA Astrophysics Data System (ADS)

    LeBlanc, Michael; Nawano, Aya; Wright, Wendelin J.; Gu, Xiaojun; Uhl, J. T.; Dahmen, Karin A.

    2016-11-01

    Extracting avalanche distributions from experimental microplasticity data can be hampered by limited time resolution. We compute the effects of low time resolution on avalanche size distributions and give quantitative criteria for diagnosing and circumventing problems associated with low time resolution. We show that traditional analysis of data obtained at low acquisition rates can lead to avalanche size distributions with incorrect power-law exponents or no power-law scaling at all. Furthermore, we demonstrate that it can lead to apparent data collapses with incorrect power-law and cutoff exponents. We propose new methods to analyze low-resolution stress-time series that can recover the size distribution of the underlying avalanches even when the resolution is so low that naive analysis methods give incorrect results. We test these methods on both downsampled simulation data from a simple model and downsampled bulk metallic glass compression data and find that the methods recover the correct critical exponents.

  17. The TDCpix Readout ASIC: A 75 ps Resolution Timing Front-End for the Gigatrackerof theNA62 Experiment

    NASA Astrophysics Data System (ADS)

    Rinella, G. Aglieri; Fiorini, M.; Jarron, P.; Kaplon, J.; Kluge, A.; Martin, E.; Morel, M.; Noy, M.; Perktold, L.; Poltorak, K.

    NA62 is an experiment under development at the CERN Super Proton Synchrotron, aiming at measuring ultra rare kaon decays. The Gigatracker (GTK) detector shall combine on-beam tracking of individual particles with a time resolution of 150 ps rms. The peak flow of particles crossing the detector modules reaches 1.27 MHz/mm2 fora total rateof about 0.75 GHz.Ahybrid siliconpixel detectoris beingdevelopedto meet these requirements. The pixel chip for the Gigatracker (TDCpix) is under design. The TDCpix chip will feature 1800 square pixels of 300×300 μm2 arranged in a matrix of 45 rows × 40 columns. Bump-bonded to a silicon pixel sensor it shall perform time stamping of particle hits with a timing accuracybetter than 200 ps rms and a detection efficiencyabove 99%. The chosen architecture provides full separation of the sensitive analog amplifiers of the pixel matrix from the noisy digital circuits of the TDCs and of the readout blocks. Discriminated hit signals from each pixel are transmitted to the end of column region. An array ofTime to Digital Converters (TDC) is implemented at the bottom of the pixel array. The TDCs are based on time tagging the events with the fine time codes generated by Delay Locked Loops (DLL) and have a nominal time bin of ˜100 ps. Time stamps and time-over-threshold are recorded for each discriminated hit and the correction of the discriminator's time-walk is performed off-detector. Data are continuously transmitted on four 2.4 Gb/s serial output links. Adescription of the on-going design of the final TDCpix is given in this paper. Design choices and some technical implementation details are presented. Aprototype ASIC including thekeycomponents of this architecture has been manufactured. The achievement of specification figures such as a time resolution of the processing chain of 75 ps rms as well as charged particle time stampingwitha resolutionbetterthan200psrmswere demonstratedexperimentally.Asummaryoftheseresultsisalso presented in

  18. Enhancement of temporal resolution using improved time-variant spectral whitening

    NASA Astrophysics Data System (ADS)

    Hariri Naghadeh, Diako; Morley, Christopher Keith

    2017-08-01

    Time-variant spectral whitening was introduced as a powerful method to enhance temporal resolution. Despite all the benefits the method carries, some negative points include balancing all kinds of amplitudes and affecting high reflections that show the effect of fluids or lithology changing and creating a Gibbs phenomenon when the objective is to enhance resolution. Synthetic and real data sets were used to highlight those weaknesses and some new steps were added to the methodology to improve and overcome the problems. The improved technique can whiten the spectrum more without sacrificing or touching high reflection amplitudes. To apply this method large Gaussian windows were shifted. These windows had frequency bandwidths equal to 70 Hz. An overlap of 90% between subsequent windows was chosen to extract the frequency components. The gain function for each component was measured from the inverse of an area-based envelope. Summation of the product of each frequency component with its own gain function achieves an enhanced trace. Comparison of the rms amplitude attributes computed from the general method and from our improved method shows that the general time-variant spectral whitening decreases the levels of high amplitudes and boosts low amplitudes considerably, which makes differentiation between amplitudes impossible.

  19. High-time-resolution laser spectrometer

    NASA Astrophysics Data System (ADS)

    Kiryunikov, K. V.; Kochubeĭ, S. A.; Lisitsyn, V. N.; Chapovskiĭ, P. L.

    1980-04-01

    A pulsed laser spectrometer was developed on the basis of a tunable He-Ar high-pressure laser. The accuracy of synchronizing the laser with an object being investigated was ~ 1 nsec. In order to automate the measurements, pulse voltmeters having a wide dynamic range and devices for analog processing of the signals were developed. The spectrometer was used to investigate the characteristics of the 2p10-ls5 transition in argon, in a nanosecond electric-discharge plasma. Measurements were made of the time dependence of the gain at the center of the transition and of the collisional broadening due to the helium (19 GHz/atm).

  20. High-time-resolution laser spectrometer

    NASA Astrophysics Data System (ADS)

    Kiriunikov, K. V.; Kochubei, S. A.; Lisitsyn, V. N.; Chapovskii, P. L.

    1980-04-01

    The paper presents a pulsed laser spectrometer which employs a tunable high-pressure He-Ar laser. A synchronization accuracy of 1 ns is obtained between the tunable laser and the object under study. Automated measurements are achieved by means of pulsed voltmeters with a wide dynamic range and analog signal processors. The spectrometer was used to study the 2p(10)-1s(5) transition in argon in the plasma of a nanosecond electric discharge. Gain vs time in the center of the transition and the collisional broadening by helium (19 GHz/atm) have been measured.

  1. Factors influencing timing resolution in a commercial LSO PETcamera

    SciTech Connect

    Moses, William W.; Ullisch, Marcus

    2004-10-23

    The CPS Accel is a commercial PET camera based on a block detector with 64 LSO scintillator crystals (each 6.75 x 6.75 x 25 mm)read out with 4 photomultiplier tubes. The excellent timing resolution of LSO suggests that this camera might be used for time-of-flight (TOF) PET, thereby reducing the statistical noise significantly. Although the Accel achieves 3 ns coincidence resolution (a factor of two better than BGO-based PET cameras), its timing resolution is nearly an order of magnitude worse than that demonstrated with individual LSO crystals. This paper quantifies the effect on the timing of each component in the Accel timing chain to identify which components most limit the camera's timing resolution. The components in the timing chain are: the scintillator crystal, the photomultiplier tube (PMT), the constant fraction discriminator (CFD), and the time to digital converter (TDC). To measure the contribution of each component, we construct a single crystal test system with high-performance versions of these components. This system achieves 221 ps fwhm coincidence timing resolution, which is used as a baseline measurement. One of the high-performance components is replaced by a production component, the coincidence timing resolution is re-measured, and the difference between measurements is the contribution of that (production) component. We find that the contributions of the TDC, CFD, PMT, and scintillator are 2000 ps, 1354 ps, 422 ps, and 326 psfwhm respectively, and that the overall timing resolution scales like the square root of the amount of scintillation light detected by the PMT. Based on these measurements we predict that the limit for the coincidence timing resolution in a practical, commercial, LSO-based PET camera is 528ps fwhm.

  2. Time resolution of core flow models

    NASA Astrophysics Data System (ADS)

    Gillet, N.; Pais, A.; Jault, D.

    2008-12-01

    We estimate the robust component of quasi-geostrophic surface core flow models from two secular variation models spanning respectively the periods 1960-2002 (CM4) and 1997-2008 (xCHAOS). We rely on stochastic models to account for the contributions of the hidden small-scale magnetic field at the core-mantle boundary (CMB) interacting with core surface flows to the observed magnetic field changes. These contributions amount to errors of representativeness in the inversion of the radial induction equation at the CMB, which dominate the error budget. Taking into account the finite correlation time of the small scale magnetic field, we find that these errors of representativeness also have finite correlation time, of the order of 10 years. Our conclusion that the advection of the small scale magnetic field does not strongly contribute to the changes of the magnetic field occuring in less than 10 years -such as the geomagnetic jerks- implies that these changes should be well accounted for by core flow models. Our core flow models show, at all epochs, a grand westward current circling around the cylindrical surface tangent to the inner core, at approximately 30° and 60° latitude under the Indian and Pacific oceans, respectively. They account well for the changes in core angular momentum for the most recent epochs. We show that the interaction between the hidden magnetic field and core motions also cause apparent changes of the magnetic flux at the core-mantle boundary, which may be misunderstood as evidence for magnetic diffusion.

  3. Prospects for Electron Imaging with Ultrafast Time Resolution

    SciTech Connect

    Armstrong, M R; Reed, B W; Torralva, B R; Browning, N D

    2007-01-26

    Many pivotal aspects of material science, biomechanics, and chemistry would benefit from nanometer imaging with ultrafast time resolution. Here we demonstrate the feasibility of short-pulse electron imaging with t10 nanometer/10 picosecond spatio-temporal resolution, sufficient to characterize phenomena that propagate at the speed of sound in materials (1-10 kilometer/second) without smearing. We outline resolution-degrading effects that occur at high current density followed by strategies to mitigate these effects. Finally, we present a model electron imaging system that achieves 10 nanometer/10 picosecond spatio-temporal resolution.

  4. 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.

  5. 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.

  6. 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.

  7. Recipes for high resolution time-of-flight detectors

    SciTech Connect

    Anz, S.J. |; Felter, T.E.; Hess, B.V.; Daley, R.S.; Roberts, M.L.; Williams, R.S.

    1995-01-01

    The authors discuss the dynamics, construction, implementation and benefits of a time-of-flight (TOF) detector with count rates an order of magnitude higher and resolution three to four times better than that obtainable with a surface barrier detector. The propose use of design criteria for a time-of-flight detector is outlined, and the determination of a TOF detector`s total relative timing error and how this value determines the mass resolution are illustrated using a graphical analysis. They present simulation and experimental examples employing light ions and discuss advantages and pitfalls of medium-energy heavy ion TOF spectrometry.

  8. 400-ps time resolution with a passively quenched avalanche photodiode.

    PubMed

    Grayson, T P; Wang, L J

    1993-06-01

    Avalanche photodiodes (APD's) operated in a single-photon-counting Geiger mode are becoming attractive alternatives to photomultiplier tubes for low-light-level detection and signal timing. By paying careful attention to the design and construction of a simple APD passive quenching circuit to reduce stray capacitances, we directly measured a time resolution of 410 ps FWHM for a commercial APD. A more detailed data analysis shows the actual time resolution to be ~ 390 ps FWHM. This is believed to be the most accurate time response for such a simple, inexpensive, and widely available device achieved to date.

  9. The time resolution domain of stellar radio astronomy

    NASA Astrophysics Data System (ADS)

    Bookbinder, J.

    1985-07-01

    High time resolution (HTR) radio observations of stellar sources is a very young technique. One of the main limitations on HTR observations is the refusal of stars to cooperate with the observer - i.e. low flare rates. Instrumental problems, obtaining the necessary sensitivity (i.e. low noise) on short integration times is also a major problem. Few instruments are likely to excel Arecibo or the VLA for this mode of observing. High time resolution observations are necessary to determine the nature of both the acceleration and emission mechanisms responsible for the short-lived radio phenomena that have already been observed.

  10. A new timing model for calculating the intrinsic timing resolution of a scintillator detector.

    PubMed

    Shao, Yiping

    2007-02-21

    The coincidence timing resolution is a critical parameter which to a large extent determines the system performance of positron emission tomography (PET). This is particularly true for time-of-flight (TOF) PET that requires an excellent coincidence timing resolution (<1 ns) in order to significantly improve the image quality. The intrinsic timing resolution is conventionally calculated with a single-exponential timing model that includes two parameters of a scintillator detector: scintillation decay time and total photoelectron yield from the photon-electron conversion. However, this calculation has led to significant errors when the coincidence timing resolution reaches 1 ns or less. In this paper, a bi-exponential timing model is derived and evaluated. The new timing model includes an additional parameter of a scintillator detector: scintillation rise time. The effect of rise time on the timing resolution has been investigated analytically, and the results reveal that the rise time can significantly change the timing resolution of fast scintillators that have short decay time constants. Compared with measured data, the calculations have shown that the new timing model significantly improves the accuracy in the calculation of timing resolutions.

  11. Study of Saturn electrostatic discharges with high time resolution

    NASA Astrophysics Data System (ADS)

    Zakharenko, V.; Mylostna, K.; Konovalenko, A.; Kolyadin, V.; Zarka, P.; Griessmeier, J.-M.; Litvinenko, G.; Sidorchuk, M.; Rucker, H.; Fischer, G.; Cecconi, B.; Coffre, A.; Denis, L.; Shevchenko, V.; Nikolaenko, V.

    2013-09-01

    Ground-based observations of SED (Saturn Electrostatic Discharges) with high time resolution are the next stage of extraterrestrial atmospheric processes study. Due to extremely high intensity of Saturn's storm J (2010) [1] we have obtained the records with high signal-to-noise (S/N) ratio with the time resolution of 15 ns. It permitted us to investigate the microsecond structure of lightning and clearly distinguish SED in the presence of local interference in virtue of a dispersive delay of extraterrestrial planetary signals.

  12. Time stamping of single optical photons with 10 ns resolution

    NASA Astrophysics Data System (ADS)

    Chakaberia, Irakli; Cotlet, Mircea; Fisher-Levine, Merlin; Hodges, Diedra R.; Nguyen, Jayke; Nomerotski, Andrei

    2017-05-01

    High spatial and temporal resolution are key features for many modern applications, e.g. mass spectrometry, probing the structure of materials via neutron scattering, studying molecular structure, etc.1-5 Fast imaging also provides the capability of coincidence detection, and the further addition of sensitivity to single optical photons with the capability of timestamping them further broadens the field of potential applications. Photon counting is already widely used in X-ray imaging,6 where the high energy of the photons makes their detection easier. TimepixCam is a novel optical imager,7 which achieves high spatial resolution using an array of 256×256 55 μm × 55μm pixels which have individually controlled functionality. It is based on a thin-entrance-window silicon sensor, bump-bonded to a Timepix ASIC.8 TimepixCam provides high quantum efficiency in the optical wavelength range (400-1000 nm). We perform the timestamping of single photons with a time resolution of 20 ns, by coupling TimepixCam to a fast image-intensifier with a P47 phosphor screen. The fast emission time of the P479 allows us to preserve good time resolution while maintaining the capability to focus the optical output of the intensifier onto the 256×256 pixel Timepix sensor area. We demonstrate the capability of the (TimepixCam + image intensifier) setup to provide high-resolution single-photon timestamping, with an effective frame rate of 50 MHz.

  13. High time resolution ion temperature profile measurements on PBX

    SciTech Connect

    Gammel, G.; Kaita, R.; Fonck, R.; Jaehnig, K.; Powell, E.

    1986-05-01

    Ion temperature profiles with a time resolution of 2 to 5 ms have been measured on PBX by charge-exchange-recombination spectroscopy (CXRS) and a neutral-particle charge-exchange analyzer (NPA). The sightlines of both diagnostics crossed the trajectory of a near-perpendicular heating beam, which enhanced the local neutral density (proportional to signal strength) and provided spatial resolution. The time resolution of these two independent techniques is sufficient to see sawtooth oscillations and other MHD activity. Effects of these phenomena on the toroidal rotation velocity profile, v/sub phi/(r), are clearly observed by CXRS. For example, a sharp drop in the central v/sub phi/ occurs at the sawtooth crash, followed by a linear rise during the quiescent phase. The NPA results are compared with those from CXRS.

  14. Optimizing the Timing Resolution for the NEXT Array

    NASA Astrophysics Data System (ADS)

    Engelhardt, A.; Shadrick, S.; Rajabali, M.; Schmitt, K.; Grzywacz, R.

    2016-09-01

    In nuclear physics studies there are very few detectors capable of measuring neutron energies in the 0.1-10 MeV energy range with a reasonable resolution. The VANDLE array is the premier detector array for these measurements, yet VANDLE is limited by the its thickness (2.9 cm minimum).The Neutron dEtector with Tracking (NEXT) array would be capable of surpassing the limitations caused by the large size of VANDLE bars. A proposed configuration of each neutron detector consists of ten 3-mm thick plastic scintillators with two or more silicon photomultipliers (SiPMs) attached at each end. To achieve the desired energy resolution for neutron energy measurements through time of flight, the timing resolution between these SiPMs needs to be below 200 ps. A SiPM was placed on each end of a plastic scintillator inside a light-tight electrical box along with a 137Cs source. An analog circuit was designed in order to measure the timing difference between the two SiPMs. Different configurations of SiPM sizes, scintillator sizes, and wrappings were tested in order to determine the configuration that yields the best timing resolution. Details of the testing procedures and results will be presented. Research Supported by the National Nuclear Security Administration.

  15. Singapore rhabdomyosarcoma (RMS) experience: shall we change our practice?

    PubMed

    Aung, Lele; Soe, Tin Aung; Chang, Kenneth Te; Quah, Thuan Chong

    2014-02-01

    Although rhabdomyosarcoma (RMS) constitutes nearly 4% of all children diagnosed with cancer in the ethnically diverse small island city of Singapore, it is unknown how children with RMS fare. This study investigated 50 children with RMS from April 1993 to December 2010 from KK Women's and Children's Hospital (KKH) and National University Hospital (NUH). They were treated either as per Intergroup Rhabdomyosarcoma Study Group (IRSG) or Société Internationale Pediatrique D'Oncologie (SIOP) regimens. Median age of diagnosis was 5.1 years (range, 0.1 to 17.3 years) with a median follow-up of 3.3 years (range, 0.4 to 15.6 years). According to IRSG classifi cation, 18 (36%) were staged as low-risk (LR); 19 (38%) were intermediate-risk (IR), 12 (24%) were high-risk (HR) and it was unknown in 1 patient. Twenty-nine (58%) were of embryonal subtype, 17 (34%) were alveolar and subclassification was not available in 4. The primary sites of tumour were: head and neck region (n = 22); genitourinary (n = 19); extremity (n = 10); and abdomen/retroperitoneal (n = 5). At the time of analysis, 80% were alive with no evidence of disease, 9 were dead of disease, and 2 were alive with disease. By disease risk group, the 5-year event-free survival (EFS) for LR group disease was 81.3% (95% CI, 62.0 to 100.0), IR group was 61.4% (95% CI, 32.3 to 90.4) and HR group was 25.0% (95% CI, 0.0 to 49.5) respectively (P <0.001). The 5-year EFS for risk by chemotherapy received as per SIOP vs per IRSG revealed: LR 83.3% vs 75.0% (P = 0.787); IR 83.3% vs 43.8% (P = 0.351); HR 0.0% vs 42.9% (P = 0.336) respectively. Of 15 relapses (HR, n = 7), at median of 2 years, 4 of 6 patients treated as per SIOP regimen were dead of disease and 3 of 8 treated as per IRSG were alive. Radiation therapy (RT) can be avoided in LR classification although those in higher risk classification need RT to local and distant metastatic disease. The outcome of children with RMS in Singapore can be further improved by coming

  16. Digital Signal Processing for SiPM Timing Resolution

    NASA Astrophysics Data System (ADS)

    Philippov, D. E.; Popova, E. V.; Belyaev, V. N.; Buzhan, P. Z.; Stifutkin, A. A.; Vinogradov, S. L.

    2017-01-01

    Digital signal processing (DSP) is an emerging trend in experimental studies and applications of various detectors including SiPMs. In particular, the DSP is recognized as a promising approach to improve coincidence timing resolution (CTR) of fast SiPM-based scintillation detectors. Single photon timing resolution (SPTR) is one of the key parameters affecting CTR, especially important in a case when CTR is approaching to its ultimate limits as, for example, highly demanded in Time-of-Flight PET. To study SiPM timing resolution, we developed a special DSP software and applied it to both SPTR and CTR measurements. These measurements were carried out using 3x3 mm2 KETEK SiPM samples of timing optimized and standard designs with 405 nm picosecond laser for SPTR and with 3x3x5 mm3 LYSO crystals and 511 keV Na-22 source for CRT. Results of the study are useful for further improvements of DSP algorithms and SiPM designs for fast timing.

  17. Application of RMS for damage detection by guided elastic waves

    NASA Astrophysics Data System (ADS)

    Radzieński, M.; Doliński, Ł.; Krawczuk, M.; dot Zak, A.; Ostachowicz, W.

    2011-07-01

    This paper presents certain results of an experimental study related with a damage detection in structural elements based on deviations in guided elastic wave propagation patterns. In order to excite guided elastic waves within specimens tested piezoelectric transducers have been applied. As excitation signals 5 sine cycles modulated by Hanning window have been used. Propagation of guided elastic waves has been monitored by a scanning Doppler laser vibrometer. The time signals recorded during measurement have been utilised to calculate the values of RMS. It has turned out that the values of RMS differed significantly in damaged areas from the values calculated for the healthy ones. In this way it has become possible to pinpoint precisely the locations of damage over the entire measured surface. All experimental investigations have been carried out for thin aluminium or composite plates. Damage has been simulated by a small additional mass attached on the plate surface or by a narrow notch cut. It has been shown that proposed method allows one to localise damage of various shapes and sizes within structural elements over the whole area under investigation.

  18. Astronauts Seddon and Bobko work on extension for RMS

    NASA Image and Video Library

    1985-04-15

    51D-04-015 (15 April 1985) --- Astronaut Rhea Seddon and Karol J. Bobko continue work on snag-type extension for the Remote Manipulator System (RMS) as part of an effort to activate a lever on a troubled communications satellite. Since the crew learned soon after deployment of the Syncom IV (LEASAT) spacecraft that it was not functioning properly plans were formulated for a rendezvous in space between the Discovery and the satellite. A fly swatter-like extension and another resembling a LaCrosse stick were fashioned from onboard supplies and furnishings. Stowage lockers nearby serve as a work bench for the two. At various times during the seven-day mission, the majority of the seven-member crew participated in the tool-making and preparations for an extravehicular activity (EVA) by the flights other two mission specialists -- Jeffrey A. Hoffman and S. David Griggs -- to connect the two tools to the RMS. Bobko is mission commander and Dr. Seddon, a mission specialist.

  19. 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.

  20. High Time Resolution Photon Counting 3D Imaging Sensors

    NASA Astrophysics Data System (ADS)

    Siegmund, O.; Ertley, C.; Vallerga, J.

    2016-09-01

    Novel sealed tube microchannel plate (MCP) detectors using next generation cross strip (XS) anode readouts and high performance electronics have been developed to provide photon counting imaging sensors for Astronomy and high time resolution 3D remote sensing. 18 mm aperture sealed tubes with MCPs and high efficiency Super-GenII or GaAs photocathodes have been implemented to access the visible/NIR regimes for ground based research, astronomical and space sensing applications. The cross strip anode readouts in combination with PXS-II high speed event processing electronics can process high single photon counting event rates at >5 MHz ( 80 ns dead-time per event), and time stamp events to better than 25 ps. Furthermore, we are developing a high speed ASIC version of the electronics for low power/low mass spaceflight applications. For a GaAs tube the peak quantum efficiency has degraded from 30% (at 560 - 850 nm) to 25% over 4 years, but for Super-GenII tubes the peak quantum efficiency of 17% (peak at 550 nm) has remained unchanged for over 7 years. The Super-GenII tubes have a uniform spatial resolution of <30 μm FWHM ( 1 x106 gain) and single event timing resolution of 100 ps (FWHM). The relatively low MCP gain photon counting operation also permits longer overall sensor lifetimes and high local counting rates. Using the high timing resolution, we have demonstrated 3D object imaging with laser pulse (630 nm 45 ps jitter Pilas laser) reflections in single photon counting mode with spatial and depth sensitivity of the order of a few millimeters. A 50 mm Planacon sealed tube was also constructed, using atomic layer deposited microchannel plates which potentially offer better overall sealed tube lifetime, quantum efficiency and gain stability. This tube achieves standard bialkali quantum efficiency levels, is stable, and has been coupled to the PXS-II electronics and used to detect and image fast laser pulse signals.

  1. 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.

  2. 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.

  3. 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.

  4. High Resolution, Real-Time Interferometer for Coherent Beam Combination

    NASA Astrophysics Data System (ADS)

    Simion, Sandel; Blanaru, Constantin; Ursescu, Daniel

    2010-04-01

    Piston errors introduced during the pumping of high energy amplifiers in the laser chains are estimated to produce significant distortion and dramatically reduce the intensity of the combined beam resulted from the Coherent Beam Combination (CBC) of ultra intense short pulses. For monitoring the phase and optical path shift, we developed a high resolution real time interferometer. Based on the code counting method, the device is suitable for high speed/real time measurements and is immune to vibrations which might appear in the laser system. The device consists of an analog stage which generates the counting code, later processed by the microprocessor unit (CPU). The analog stage ensures 20 nm resolution, 2 m/s optical path variation speed measurements and has low sensitivity to variations of quadrature signals amplitude. The CPU is based on a complex programmable logic device (CPLD), with 8 ns processing time of the signals. The algorithm provides simultaneously measurements with increasing speed for lower resolution (20 nm at 2 m/s, 40 nm at 4 m/s and 80 nm at 8 m/s), making the system fault tolerant at high speed fluctuations of the optical path. The device contains also a digital-to-analog converter stage, making the instrument suitable for implementation of closed loop control.

  5. 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

  6. 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.

  7. 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.

  8. Currie at RMS controls on the aft flight deck

    NASA Image and Video Library

    1998-12-05

    S88-E-5010 (12-05-98) --- Operating at a control panel on Endeavour's aft flight deck, astronaut Nancy J. Currie works with the robot arm prior to mating the 12.8-ton Unity connecting module to Endeavour's docking system. The mating took place on late afternoon of Dec. 5. A nearby monitor provides a view of the remote manipulator system's (RMS) movements in the cargo bay. The feat marked an important step in assembling the new International Space Station. Manipulating the shuttle's 50-foot-long robot arm, Currie placed Unity just inches above the extended outer ring on Endeavour's docking mechanism, enabling Robert D. Cabana, mission commander to fire downward maneuvering jets, locking the shuttle's docking system to one of two Pressurized Mating Adapters (PMA) attached to Unity. The mating occurred at 5:45 p.m. Central time, as Endeavour sailed over eastern China.

  9. 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.

  10. View of the Columbia's remote manipulator system (RMS)

    NASA Image and Video Library

    1982-11-13

    STS002-13-226 (13 Nov. 1981) --- Backdropped against Earth's horizon and the darkness of space, the space shuttle Columbia's remote manipulator system (RMS) gets its first workout in zero-gravity during the STS-2 mission. A television camera is mounted near the elbow and another is partially visible near the wrist of the RMS. Photo credit: NASA

  11. Astronaut Claude Nicollier participates in RMS training at MSFC

    NASA Image and Video Library

    1993-06-15

    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.

  12. 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.

  13. Financing development stage biotechnology companies: RMs vs. IPOs.

    PubMed

    Ahn, Mark J; Couch, Robert B; Wu, Wei

    2011-01-01

    We examine reverse mergers (RMs) in the biotechnology industry and find that, when compared to initial public offerings (IPOs), RMs are smaller, have significantly lower market valuations relative to size, and generally invest less. We also find that RMs exhibit positive abnormal returns on the announcement date and throughout the first year after the RM event. In looking at liquidity measures, we find that RMs tend to be less liquid than IPOs and that illiquidity is greater during the six-month lock-up period following the RM event. Thus, RMs may be an appropriate alternative financing vehicle in capital intensive, high-risk biotechnology companies which require accessing deeper and larger pools of investors in public capital markets across multiple milestone periods in a "pay for progress" environment.

  14. A microprocessor-based true-RMS line voltage monitor

    NASA Astrophysics Data System (ADS)

    Silberberg, J. L.

    1981-08-01

    A true-root-mean-square (RMS) line voltage monitor (LVM) was developed for use in determining compliance with the performance standard for diagnostic X-ray equipment. The instrument measures ac voltage with less than plus or minus 0.1 percent error over a wide range of voltage and frequency. It is compact and lightweight and thus suitable for field use. The theory of operation, system hardware and software, and performance characteristics of the true-RMS LVM. The true-RMS LVM is capable of measuring ac voltage and frequency over a frequency range of 16 to 1600 Hz. For RMS inputs between 60 and 650 V, the maximum voltage error is plus or minus 0.2 V over this frequency range. From 16 to 100 Hz, the RMS value of the input voltage is computed for each cycle. The LVM is also capable of measuring dc voltage.

  15. Olfactory deficits decrease the time resolution for trigeminal lateralization.

    PubMed

    Oleszkiewicz, A; Meusel, T; Güpfert, M; Westermann, B; Hummel, T; Welge-Lüssen, A

    2017-09-15

    To date the temporal resolution of the detection of almost simultaneously applied intranasal trigeminal stimuli is unknown. The aim of our study was to examine this temporal resolution in an/hyposmic subjects, who are known to have reduced trigeminal sensitivity and compare it with healthy controls. Participants were 20 posttraumatic an/hyposmic patients, and 23 healthy controls (matched with regard to sex and age). Olfactory function was tested psychophysically using the Sniffin´ Sticks test battery. Bilateral trigeminal stimulation was carried out using a birhinal high-precision olfactometer. The trigeminal stimulus used was CO₂ 60% v/v, the interstimulus interval ranged from 28 to 32s, stimulus duration was 200ms. Time-lags tested between right and left side of stimulation were at 40, 80, 120, 160 and 200ms. Subjects raised their left or right hand to indicate the side on which the stimulus had been perceived first. In both groups the accuracy in the trigeminal lateralization task increased with the time-lag but normosmic subjects significantly outperformed an/hyposmics in the 200ms time-lag condition. Normosmics significantly exceeded 50% chance level at the time-lag of 80ms, whereas an/hyposmics were only able to score above chance starting from 120ms time-lag. Lateralization scores significantly decreased with age. At a time lag of 200ms intranasal trigeminal stimuli can be lateralized. The reduced trigeminal sensitivity in patients with anosmia or hyposmia leads to an increased time lag required for correct perception of intranasal, almost simultaneously, applied stimuli. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. 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.

  17. Towards neutron scattering experiments with sub-millisecond time resolution

    DOE PAGES

    Adlmann, F. A.; Gutfreund, Phillip; Ankner, John Francis; ...

    2015-02-01

    Neutron scattering techniques offer several unique opportunities in materials research. However, most neutron scattering experiments suffer from the limited flux available at current facilities. This limitation becomes even more severe if time-resolved or kinetic experiments are performed. A new method has been developed which overcomes these limitations when a reversible process is studied, without any compromise on resolution or beam intensity. We demonstrate that, by recording in absolute time the neutron detector events linked to an excitation, information can be resolved on sub-millisecond timescales. Specifically, the concept of the method is demonstrated by neutron reflectivity measurements in time-of-flight mode atmore » the Liquids Reflectometer located at the Spallation Neutron Source, Oak Ridge National Laboratory, Tennessee, USA, combined with in situ rheometry. Finally, the opportunities and limitations of this new technique are evaluated by investigations of a micellar polymer solution offering excellent scattering contrast combined with high sensitivity to shear.« less

  18. Towards neutron scattering experiments with sub-millisecond time resolution

    SciTech Connect

    Adlmann, F. A.; Gutfreund, Phillip; Ankner, John Francis; Browning, James F.; Parizzi, Andre A.; Vacaliuc, Bogdan; Halbert, Candice E.; Rich, J. P.; Dennison, A. J. C.; Wolff, Max

    2015-02-01

    Neutron scattering techniques offer several unique opportunities in materials research. However, most neutron scattering experiments suffer from the limited flux available at current facilities. This limitation becomes even more severe if time-resolved or kinetic experiments are performed. A new method has been developed which overcomes these limitations when a reversible process is studied, without any compromise on resolution or beam intensity. We demonstrate that, by recording in absolute time the neutron detector events linked to an excitation, information can be resolved on sub-millisecond timescales. Specifically, the concept of the method is demonstrated by neutron reflectivity measurements in time-of-flight mode at the Liquids Reflectometer located at the Spallation Neutron Source, Oak Ridge National Laboratory, Tennessee, USA, combined with in situ rheometry. Finally, the opportunities and limitations of this new technique are evaluated by investigations of a micellar polymer solution offering excellent scattering contrast combined with high sensitivity to shear.

  19. 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.

  20. 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.

  1. A 2.5 mW/ch, 50 Mcps, 10-Analog Channel, Adaptively Biased Read-Out Front-End IC With Low Intrinsic Timing Resolution for Single-Photon Time-of-Flight PET Applications With Time-Dependent Noise Analysis in 90 nm CMOS.

    PubMed

    Cruz, Hugo; Huang, Hong-Yi; Luo, Ching-Hsing; Lee, Shuenn-Yuh

    2017-04-01

    This paper presents a 10-channel time-of-flight application-specific integrated circuit (ASIC) for positron emission tomography in a 90 nm standard CMOS process. To overcome variations in channel-to-channel timing resolution caused by mismatch and process variations, adaptive biases and a digital-to-analog converter (DAC) are utilized. The main contributions of this work are as follows. First, multistage architectures reduce the total power consumption, and detection bandwidths of analog preamplifiers and comparators are increased to 1 and 1.5 GHz, respectively, relative to those in previous studies. Second, a total intrinsic electronic timing resolution of 9.71 ps root-mean-square (RMS) is achieved (13.88 ps peak and 11.8 ps average of the 10 channels in 5 ASICs). Third, the proposed architecture reduces variations in channel-to-channel timing resolution to 2.6 bits (equivalent to 4.17 ps RMS) by calibrating analog comparator threshold levels. A 181.5 ps full-width-at-half-maximum timing resolution is measured with an avalanche photo diode and a laser setup. The power consumption is 2.5 mW using 0.5 and 1.2 V power supplies. The proposed ASIC is implemented in a 90 nm TSMC CMOS process with a total area of 3.3 mm × 2.7 mm.

  2. 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

  3. Convex Optimization of Coincidence Time Resolution for a High-Resolution PET System

    PubMed Central

    Reynolds, Paul D.; Olcott, Peter D.; Pratx, Guillem; Lau, Frances W. Y.

    2013-01-01

    We are developing a dual panel breast-dedicated positron emission tomography (PET) system using LSO scintillators coupled to position sensitive avalanche photodiodes (PSAPD). The charge output is amplified and read using NOVA RENA-3 ASICs. This paper shows that the coincidence timing resolution of the RENA-3 ASIC can be improved using certain list-mode calibrations. We treat the calibration problem as a convex optimization problem and use the RENA-3’s analog-based timing system to correct the measured data for time dispersion effects from correlated noise, PSAPD signal delays and varying signal amplitudes. The direct solution to the optimization problem involves a matrix inversion that grows order (n3) with the number of parameters. An iterative method using single-coordinate descent to approximate the inversion grows order (n). The inversion does not need to run to convergence, since any gains at high iteration number will be low compared to noise amplification. The system calibration method is demonstrated with measured pulser data as well as with two LSO-PSAPD detectors in electronic coincidence. After applying the algorithm, the 511 keV photopeak paired coincidence time resolution from the LSO-PSAPD detectors under study improved by 57%, from the raw value of 16.3 ± 0.07 ns full-width at half-maximum (FWHM) to 6.92 ± 0.02 ns FWHM (11.52 ± 0.05 ns to 4.89 ± 0.02 ns for unpaired photons). PMID:20876008

  4. 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.

  5. Optimizing Spectral Resolution and Observation Time for Measurements of Habitability

    NASA Astrophysics Data System (ADS)

    Khalfa, N.; Meadows, V. S.; Domagal-Goldman, S. D.

    2009-12-01

    The Terrestrial Planet Finder (TPF) is a NASA mission concept that will attempt to characterize and search for habitability and life on extrasolar planets. While detection of a planet in the habitable zone increases the probability that the planet is habitable, planetary characterization will be required to confirm habitability and thereby test predictions of the position of the habitable zone. The TPF-I mission will accomplish this with an interferometer, allowing the detection of Earth-mass planets around stars up to 15 pc away and production of mid-infrared spectra from those planets. The focus on the mid-infrared region of the spectrum (7-20 mm) is beneficial because this is where energy from Earth-like planets is strongest relative to the flux from their parent stars. To discover if such planets are habitable we need to know not only what to look for - biosignatures and indicators of habitability - but also how to look. In other words, we must determine the trade-off in telescope properties that will provide the best science return. Extensive models have been made of Earth-like planets to describe many planetary properties, including atmospheric chemistry and surface temperature. Those properties may be derived for extrasolar planets using these models if spectra are obtained for the target planet. When modeling a planet, we can calculate a very high-resolution spectrum that can show the detailed absorption features of gases such as CO2, H2O, and O3. However, the telescope resolution will necessarily be limited by low photon fluxes from the distant targets. Alternatively, the telescope could spend more time taking in photons from each target planet. A balance may have to be struck between the numbers of targets observed and the quality of the data obtained for each target. We will present a number of simulations of TPF instrument measurements of terrestrial spectra that parametrize spectral resolution and observation time. The relative errors of these various

  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. 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

  8. Nimbus 6 satellite vs rawinsonde capabilities. [RMS errors in temperature, wind and geopotential height data

    NASA Technical Reports Server (NTRS)

    Scoggins, J. R.; Petti, G. S.

    1978-01-01

    The paper establishes rms errors in Nimbus 6 satellite data from discrepancies between satellite and rawinsonde data, compares rms errors in Nimbus 6 with those in rawinsonde data, and examines the capability of Nimbus 6 satellite data to depict such quantities as horizontal gradients of basic variables and computed variables such as vorticity and lapse rate of temperature. The capability of Nimbus 6 data is illustrated by comparisons of rms errors in computed variables obtained through a propagation-of-error method with average and near-extreme values of the variables obtained from two of NASA's Atmospheric Variability Experiments (AVE II and AVE IV). It is shown that the rms errors in Nimbus 6 basic variables (temperature, mixing ratio, geopotential height, and wind speed) are between 2 and 12 times larger than the corresponding errors in rawinsonde data. For all variables examined, the magnitude of the rms errors are smaller than the near-extreme values of the variables determined from AVE II and AVE IV data.

  9. 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

  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. 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.

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

    NASA Image and Video Library

    1994-11-14

    STS066-13-014 (3-14 Nov. 1994) --- On the space shuttle Atlantis' aft flight deck, astronaut Ellen Ochoa, payload commander, has just completed an operation 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. Photo credit: NASA

  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. Photoacoustic cell for dynamic measurements with nanosecond time resolution

    NASA Astrophysics Data System (ADS)

    Puchenkov, Oleg V.; Malkin, Shmuel

    1996-03-01

    A design of a photoacoustic (PA) cell for dynamic measurements in liquid samples with nanosecond time resolution is presented. The design is based on a layered scheme of laser-induced sound excitation and detection. A theoretical basis for the use of the cell in dynamic PA diagnostics and in pulsed acoustic spectroscopy is given. The cell parameters which determine its performance in both applications are established, and ways of cell optimization are discussed. The validity of the theoretical description was proven in a set of calibration experiments. The functioning of the cell as a PA-diagnostics device was tested on a model photochemical system (the quenching of the triplet state of benzophenone by 2,5-dimethyl-2,4-hexadiene). With a slight modification the cell was used for pulsed broadband acoustic spectroscopy to probe the structural relaxation in formic acid in the frequency range of 2-20 MHz.

  16. High resolution geodetic techniques for monitoring fluid levels over time

    NASA Astrophysics Data System (ADS)

    Hare, Jennifer Thompson

    1998-11-01

    In the first study, a novel surveillance technique is developed in which surface gravity observations are used to monitor the progress of a gas cap waterflood in the 8200 ft (2500 m) deep Prudhoe Bay reservoir, Alaska. This cost-effective method requires that high-precision gravity surveys be repeated every 3 to 5 years. Differences in the gravity field with time reflect changes in the reservoir fluid density distribution. A preliminary field test at Prudhoe Bay indicates survey accuracy of 5 to 10 mu Gal can be achieved for gravity data using a modified Lacoste & Romberg "G" type meter or Scintrex CG-3M combined with Global Positioning System (GPS) positioning. Forward gravity modeling of a suite of reservoir simulations of the proposed waterflood predicts variation in surface measurements of 100 mu Gal after 5 years of injection, and 180 to 250 mu Gal after 15 years. A constrained, least-squares method is used to invert synthetic gravity data for subsurface density distributions. The modeling procedure has been formulated to allow testing of the models for sensitivity to gravity sampling patterns, noise characteristics, and various constraints on model parameters such as density range, total mass, and model moment of inertia. Horizontal feature resolution of the waterflood is about 5000 ft (1520 m) for constrained inverse models from synthetic gravity with 5 mu Gal standard deviation noise. Results of the modeling indicate that inversion of time-lapse gravity data is a viable and promising technique for monitoring reservoir gas cap waterfloods. In the second study, the problem of how to estimate ancient lake levels from the geomorphology of remnant shoreline terraces is investigated. High resolution, GPS controlled, topographic data from around the highstand shoreline of Pleistocene Lake Lahontan in western Nevada provide the means for isolating coherent terrace features which are related to the paleoshoreline level. Determination of an unambiguous point or

  17. Comparison of Peak and RMS Gains for Discrete Time Systems,

    DTIC Science & Technology

    1986-01-01

    AC-29 #1, pp9-16, Jan. 1984. [DES]C. A. Desoer and M. Vidyasagar, Feedback Systems: Input-Output Properties, Academic Press, New York 1975. [DAH] M. A...LM -10 - [MULI C. T. Mullis and R. A. Roberts, Synthesis of minimum roundoff noise fixed point digital ifiters, IEEE Trans. Circuits Syst., vol. CAS...23 #9, pp55l-56l, Sept. 1976. [THIIL. Thiele, Design of sensitivity and roundoff noise optimal state space discrete systems, Int. J. of Circuit Theory and App!., vol. 12, pp39-46 , 1984. 44lr t ~- IL

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    SciTech Connect

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

    2016-05-15

    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.

  20. Determining time resolution of microchannel plate detectors for electron time-of-flight spectrometers

    SciTech Connect

    Zhang Qi; Zhao Kun; Chang Zenghu

    2010-07-15

    The temporal resolution of a 40 mm diameter chevron microchannel plate (MCP) detector followed by a constant fraction discriminator and a time-to-digital converter was determined by using the third order harmonic of 25 fs Ti:sapphire laser pulses. The resolution was found to deteriorate from 200 to 300 ps as the total voltage applied on the two MCPs increased from 1600 to 2000 V. This was likely due to a partial saturation of the MCP and/or the constant fraction discriminator working with signals beyond its optimum range of pulse width and shape.

  1. Scanning SQUID sampler with 40-ps time resolution.

    PubMed

    Cui, Zheng; Kirtley, John R; Wang, Yihua; Kratz, Philip A; Rosenberg, Aaron J; Watson, Christopher A; Gibson, Gerald W; Ketchen, Mark B; Moler, Kathryn A

    2017-08-01

    Scanning Superconducting QUantum Interference Device (SQUID) microscopy provides valuable information about magnetic properties of materials and devices. The magnetic flux response of the SQUID is often linearized with a flux-locked feedback loop, which limits the response time to microseconds or longer. In this work, we present the design, fabrication, and characterization of a novel scanning SQUID sampler with a 40-ps time resolution and linearized response to periodically triggered signals. Other design features include a micron-scale pickup loop for the detection of local magnetic flux, a field coil to apply a local magnetic field to the sample, and a modulation coil to operate the SQUID sampler in a flux-locked loop to linearize the flux response. The entire sampler device is fabricated on a 2 mm × 2 mm chip and can be scanned over macroscopic planar samples. The flux noise at 4.2 K with 100 kHz repetition rate and 1 s of averaging is of order 1 mΦ0. This SQUID sampler will be useful for imaging dynamics in magnetic and superconducting materials and devices.

  2. Scanning SQUID sampler with 40-ps time resolution

    NASA Astrophysics Data System (ADS)

    Cui, Zheng; Kirtley, John R.; Wang, Yihua; Kratz, Philip A.; Rosenberg, Aaron J.; Watson, Christopher A.; Gibson, Gerald W.; Ketchen, Mark B.; Moler, Kathryn. A.

    2017-08-01

    Scanning Superconducting QUantum Interference Device (SQUID) microscopy provides valuable information about magnetic properties of materials and devices. The magnetic flux response of the SQUID is often linearized with a flux-locked feedback loop, which limits the response time to microseconds or longer. In this work, we present the design, fabrication, and characterization of a novel scanning SQUID sampler with a 40-ps time resolution and linearized response to periodically triggered signals. Other design features include a micron-scale pickup loop for the detection of local magnetic flux, a field coil to apply a local magnetic field to the sample, and a modulation coil to operate the SQUID sampler in a flux-locked loop to linearize the flux response. The entire sampler device is fabricated on a 2 mm × 2 mm chip and can be scanned over macroscopic planar samples. The flux noise at 4.2 K with 100 kHz repetition rate and 1 s of averaging is of order 1 mΦ0. This SQUID sampler will be useful for imaging dynamics in magnetic and superconducting materials and devices.

  3. RMS: a platform for managing cross-disciplinary and multi-institutional research project collaboration.

    PubMed

    Luo, Jake; Apperson-Hansen, Carolyn; Pelfrey, Clara M; Zhang, Guo-Qiang

    2014-11-30

    Cross-institutional cross-disciplinary collaboration has become a trend as researchers move toward building more productive and innovative teams for scientific research. Research collaboration is significantly changing the organizational structure and strategies used in the clinical and translational science domain. However, due to the obstacles of diverse administrative structures, differences in area of expertise, and communication barriers, establishing and managing a cross-institutional research project is still a challenging task. We address these challenges by creating an integrated informatics platform to reduce the barriers to biomedical research collaboration. The Request Management System (RMS) is an informatics infrastructure designed to transform a patchwork of expertise and resources into an integrated support network. The RMS facilitates investigators' initiation of new collaborative projects and supports the management of the collaboration process. In RMS, experts and their knowledge areas are categorized and managed structurally to provide consistent service. A role-based collaborative workflow is tightly integrated with domain experts and services to streamline and monitor the life-cycle of a research project. The RMS has so far tracked over 1,500 investigators with over 4,800 tasks. The research network based on the data collected in RMS illustrated that the investigators' collaborative projects increased close to 3 times from 2009 to 2012. Our experience with RMS indicates that the platform reduces barriers for cross-institutional collaboration of biomedical research projects. Building a new generation of infrastructure to enhance cross-disciplinary and multi-institutional collaboration has become an important yet challenging task. In this paper, we share the experience of developing and utilizing a collaborative project management system. The results of this study demonstrate that a web-based integrated informatics platform can facilitate and

  4. Digital timing: sampling frequency, anti-aliasing filter and signal interpolation filter dependence on timing resolution

    NASA Astrophysics Data System (ADS)

    Cho, Sanghee; Grazioso, Ron; Zhang, Nan; Aykac, Mehmet; Schmand, Matthias

    2011-12-01

    The main focus of our study is to investigate how the performance of digital timing methods is affected by sampling rate, anti-aliasing and signal interpolation filters. We used the Nyquist sampling theorem to address some basic questions such as what will be the minimum sampling frequencies? How accurate will the signal interpolation be? How do we validate the timing measurements? The preferred sampling rate would be as low as possible, considering the high cost and power consumption of high-speed analog-to-digital converters. However, when the sampling rate is too low, due to the aliasing effect, some artifacts are produced in the timing resolution estimations; the shape of the timing profile is distorted and the FWHM values of the profile fluctuate as the source location changes. Anti-aliasing filters are required in this case to avoid the artifacts, but the timing is degraded as a result. When the sampling rate is marginally over the Nyquist rate, a proper signal interpolation is important. A sharp roll-off (higher order) filter is required to separate the baseband signal from its replicates to avoid the aliasing, but in return the computation will be higher. We demonstrated the analysis through a digital timing study using fast LSO scintillation crystals as used in time-of-flight PET scanners. From the study, we observed that there is no significant timing resolution degradation down to 1.3 Ghz sampling frequency, and the computation requirement for the signal interpolation is reasonably low. A so-called sliding test is proposed as a validation tool checking constant timing resolution behavior of a given timing pick-off method regardless of the source location change. Lastly, the performance comparison for several digital timing methods is also shown.

  5. 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

  6. High-resolution, real-time fringe pattern profilometry

    NASA Astrophysics Data System (ADS)

    Karpinsky, Nikolaus; Lei, Shuangyan; Zhang, Song

    2009-12-01

    This paper presents some of our recent work on high-resolution, real-time 3D profilometry using a digital fringe projection method. In particular, we utilize the unique projection mechanism of a single-chip digital-light-processing (DLP) projector: sequential channel-by-channel switching. Three phase-shifted fringe patterns are encoded into the three primary color channels and switched naturally. A high-speed charge-coupled device (CCD) camera, synchronized with the projector, is used to capture each individual color channel of the projector. Because color is not desirable, the color filters of the projector are removed, and an external trigger signal is supplied to enable its projection. Since three fringe images are sufficient to reconstruction one shape, this technique can, theoretically, reach the refresh rate of a projector (typically 120 Hz). However, due to the speed limit of the camera used, the data acquisition speed is up to 180 fps, thus the 3D shape measurement speed can be as high as 60 fps, as it requires three images to recover one 3D shape. To reach simultaneous 3D data acquisition, reconstruction, and display, we developed various efficient algorithms, and used advanced graphics hardware techniques to boost the processing. In this paper, we will summarize the technologies we developed, and will present some of the research results.

  7. High-resolution, real-time fringe pattern profilometry

    NASA Astrophysics Data System (ADS)

    Karpinsky, Nikolaus; Lei, Shuangyan; Zhang, Song

    2010-03-01

    This paper presents some of our recent work on high-resolution, real-time 3D profilometry using a digital fringe projection method. In particular, we utilize the unique projection mechanism of a single-chip digital-light-processing (DLP) projector: sequential channel-by-channel switching. Three phase-shifted fringe patterns are encoded into the three primary color channels and switched naturally. A high-speed charge-coupled device (CCD) camera, synchronized with the projector, is used to capture each individual color channel of the projector. Because color is not desirable, the color filters of the projector are removed, and an external trigger signal is supplied to enable its projection. Since three fringe images are sufficient to reconstruction one shape, this technique can, theoretically, reach the refresh rate of a projector (typically 120 Hz). However, due to the speed limit of the camera used, the data acquisition speed is up to 180 fps, thus the 3D shape measurement speed can be as high as 60 fps, as it requires three images to recover one 3D shape. To reach simultaneous 3D data acquisition, reconstruction, and display, we developed various efficient algorithms, and used advanced graphics hardware techniques to boost the processing. In this paper, we will summarize the technologies we developed, and will present some of the research results.

  8. Comparison of high resolution real time ultrasonography and high resolution computed tomography in an infant with spinal dysraphism.

    PubMed

    James, H E; Scheible, W; Kerber, C; Hilton, S V

    1983-09-01

    An infant with a lumbosacral spinal subcutaneous and intraspinal lipoma involving the conus medullaris was studied with computed tomography and high resolution real time ultrasonography to determine the extent and location of the disease before operation. The high resolution ultrasonogram demonstrated the abnormality with good detail and the added advantage of real time display of the lack of pulsatile mobility of the neural elements, confirming spinal cord tethering. Spinal high resolution ultrasonography is a noninvasive diagnostic tool in infants with spinal abnormalities and should be an important part of a neurosurgeon's diagnostic support system.

  9. Checkout activity on the Remote Manipulator System (RMS) arm

    NASA Image and Video Library

    1997-02-12

    S82-E-5016 (12 Feb. 1997) --- Astronaut Steven A. Hawley, STS-82 mission specialist, controls Discovery's Remote Manipulation System (RMS), from the aft flight deck. Hawley and his crew mates are preparing for a scheduled Extravehicular Activity (EVA) with the Hubble Space Telescope (HST), which will be pulled into the Space Shuttle Discovery's cargo bay with the aid of the Remote Manipulator System (RMS). A series of EVA's will be required to properly service the giant telescope. Hawley served as a mission specialist on NASA's 1990 mission which was responsible for placing HST in Earth-orbit. This view was taken with an Electronic Still Camera (ESC).

  10. Record and Document Management System (RMS) Guidelines: Issue A

    SciTech Connect

    EATON, SHELLEY M.; NORTHROP-SALAZAR, CHRISTINE L.

    2002-12-01

    RMS Guidelines defines the processes and conventions to manage both records and documents for the ASCI Verification and Validation Program at Sandia National Laboratories, employing the ASCI V&V RMS application. It is the definitive source for all information regarding the creation, submittal, use, maintenance, and disposition of records and documents. This document is also used as evidence of meeting records management requirements as stated in DOE Order 414.1A, Quality Assurance, and Sandia National Laboratories Corporate Technical Business Practice TBP-500, Records Management.

  11. Time course of individual Ca2+ sparks in frog skeletal muscle recorded at high time resolution.

    PubMed

    Lacampagne, A; Ward, C W; Klein, M G; Schneider, M F

    1999-02-01

    Discrete Ca2+ release events (Ca2+ "sparks") were recorded in cut segments of single frog skeletal muscle fibers using a video-rate laser-scanning confocal microscope operating in line-scan mode (63 microseconds per line). Fibers loaded with the Ca2+ indicator fluo-3 were voltage clamped at a holding potential of 0 mV, briefly reprimed at -90 mV, and then strongly depolarized with a large test pulse to activate any reprimed voltage sensors. Using this high time resolution system, it was possible to record individual Ca2+ sparks at approximately 30-fold higher time resolution than previously attained. The resulting new experimental data provides a means of characterizing the time course of fluorescence during the brief (a few milliseconds) rising phase of a spark, which was not possible with the previously used 1.5-2 ms per line confocal systems. Analysis of the time course of individual identified events indicates that fluorescence begins to rise rather abruptly at the start of the spark, continues to rise at a slightly decreasing rate to a relatively sharp peak, and then declines along a quasi-exponential time course. The mean rise time of 198 sparks was 4.7 +/- 0.1 ms, and there was no correlation between rise time and peak amplitude. Average sparks constructed by temporally and spatially superimposing and summing groups of individual sparks having similar rise times gave a lower noise representation of the sparks, consistent with the time course of individual events. In theory, the rising phase of a spark provides a lower bound estimation of the time that Ca2+ ions are being released by the sarcoplasmic reticulum Ca2+ channel(s) generating the spark. The observed time course of fluorescence suggests that the Ca2+ release underlying a spark could continue at a fairly constant rate throughout the rising phase of the spark, and then stop rather abruptly at the time of the peak.

  12. A PC-Based Time Interval Counter With 200 PS Resolution

    DTIC Science & Technology

    2004-09-01

    35th Annual Precise Time and Time Interval (PTTI) Meeting 359 A PC-BASED TIME INTERVAL COUNTER WITH 200 PS RESOLUTION Józef...CMOS FPGA technology, the 200 ps resolution (1 LSB - Least Significant Bit) was achieved in single-shot measurements of time intervals within the...time counter with 200 ps resolution in a single CMOS FPGA (Complementary-Metal-Oxide- Semiconductor Field-Programmable-Gate-Array) device [1,2], as a

  13. X-ray position detection in the region of 6. mu. m RMS with wire proportional chambers

    SciTech Connect

    Fischer, J.; Radeka, V.; Smith, G.C.

    1986-04-01

    We have developed a MWPC system for x-ray detection with a position resolution in the region of 6 ..mu..m RMS (14 ..mu..m FWHM). The performance with argon, krypton or xenon at pressures from 1 to 10 atm is explored for the x-ray energy range 5 to 25 keV. At a resolution of 6 ..mu..m RMS the effects of photoelectron and Auger electron range, electronic noise, avalanche spread, lateral electron diffusion, as well as x-ray beam collimation, become of comparable magnitude. Their limiting effects on avalanche centroid fluctuation, and hence on position resolution, are investigated. The position resolution achieved in this work compares favorably with that of solid state devices. 7 refs., 6 figs.

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

    DOE PAGES

    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.

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

    SciTech Connect

    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.

  16. AmeriFlux US-Rms RCEW Mountain Big Sagebrush

    SciTech Connect

    Flerchinger, Gerald

    2017-01-01

    This is the AmeriFlux version of the carbon flux data for the site US-Rms RCEW Mountain Big Sagebrush. Site Description - The site is located on the USDA-ARS's Reynolds Creek Experimental Watershed. It is dominated by mountain big sagebrush on land managed by USDI Bureau of Land Management.

  17. 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).

  18. 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).

  19. ORFEUS-SPAS, deployment on end of RMS arm

    NASA Image and Video Library

    1996-11-20

    STS080-704-008 (19 Nov.-7 Dec. 1996) --- Backdropped against the blackness of space, the ORPHEUS - Shuttle Pallet Satellite (SPAS) spacecraft is held in the grasp of the space shuttle Columbia's Remote Manipulator System (RMS) during deploy operations in Earth-orbit.

  20. RMS end effector waiting for command and SPAS-01 nearby

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The end effector of the remote manipulator system (RMS) appears to be waiting for its next command at the top of this frame and the Shuttle pallet satellite (SPAS-01), in its free flying mode, appears nearby. The three letters legible on the SPAS stand for Messerschmitt-Boelkow-Blohm Gmbit, a West German firm.

  1. 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.

  2. High-resolution real-time ultrasonic scanner.

    PubMed

    Berson, M; Vaillant, L; Patat, F; Pourcelot, L

    1992-01-01

    High spatial resolution is required for echographic exploration of the skin, microvessels or small laboratory animals. With the scanner described here, high resolution is obtained by means of a strongly focused, wide-band 17 MHz center frequency transducer (-6 dB bandwidth: 22 MHz). The movement of this transducer above the skin provides a 6 mm wide and 5 mm deep echographic cross-section with an image rate of 15 images/s. The resolution is about 0.08 mm in axial and 0.2 to 0.3 mm in lateral directions. The device was tested on phantoms in water and in vivo on normal and pathological skin in the Department of Dermatology. With the easy-to-handle probe, explorations were made on psoriasis, basocellular carcinoma, malignant melanoma and sarcoidosis.

  3. Radiation Science Enabled by the Radiation Monitoring Subsystem (RMS) for the Planned Europa Mission

    NASA Astrophysics Data System (ADS)

    Jun, I.; Paranicas, C.; Goldsten, J. O.; Meitzler, R.; Peplowski, P. N.; Maurer, R.

    2016-12-01

    Like any mission to Jupiter, radiation is an important consideration for the planned Europa mission as it would frequently travel through Jupiter's harsh radiation environment. The entire Europa mission flight system would have to be designed to survive and meet its mission objectives in the expected radiation environment. Although a significant effort has been spent in the past decade to improve the understanding of the radiation environment at Jupiter using the data from previous missions (mostly from the data from Energetic Particle Detector onboard Galileo), our understanding of the temporal and spatial behavior of the radiation environment at Jupiter has a lot of uncertainty. In an attempt to better understand the local radiation environment during the mission and to use the data to help the operation of the spacecraft in case of possible radiation-related issues, the planned Europa mission would have a radiation monitoring sub-system (RMS) on board the spacecraft. The RMS currently envisioned will measure the total integrated ionizing dose, both inside and outside of the main spacecraft vault, by using multiple radiation-sensitive MOSFET devices, and it will sample the energetic electron environment outside the vault using two or more charge monitors under different levels of shielding. While the RMS is foremost an engineering subsystem, RMS data could be used to further Jovian/Europa radiation science, in particular the charge monitor data, which provides high-resolution measurements of dose rate at frequent intervals ( 1 s). Using RMS data, it may be possible to construct electron energy spectra as a function of position around Europa, map the estimated precipitating flux onto Europa, and characterize the dose rate at different locations in the Jovian magnetosphere. Such data products could facilitate the study of several important scientific topics: radiation-induced surface modification of Europa, survivability of complex molecules including organics, the

  4. High Resolution Prototype Real-Time Radiography System.

    DTIC Science & Technology

    1986-11-01

    hi.: changed, if you wish to ho removed from our mailinq list, or if the addressee is no longer employed by your !;-> anisation , plrase notify AFWAL...Scanner 3-19 3.4.1 Funk Star Radiographs Recorded on the 2-Inch 3-22 Breadboard Scanner 3.4.2 Compounded Modulation Transfer Function of Line Scan 3-24...Funk star pattern taken at the 1024 pixel/inch resolution mode is shown in Figure 3.4.1. This figure shows the resolution along both the

  5. 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 ) .

  6. Universal behavior of the interoccurrence times between losses in financial markets: independence of the time resolution.

    PubMed

    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 P(Q)(r) of the interoccurrence times r between losses below a negative threshold -Q, for fixed mean interoccurrence times R(Q) in multiples of the corresponding time resolutions, can be described on all time scales by the same q exponentials, P(Q)(r)∝1/{[1+(q-1)βr](1/(q-1))}. We propose that the asset- and time-scale-independent analytic form of P(Q)(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 P(Q)(r) as well as the autocorrelation C(Q)(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 P(Q)(r) and the power-law decay of C(Q)(s).

  7. 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.

  8. NIF optical specifications - the importance of the RMS gradient specification

    SciTech Connect

    Auerbach, J M; Cotton, C T; English, R E; Henesian, M A; Hunt J T; Kelly, J H; Lawson, J K; Sacks, J B; Shoup, M J; Trenholme, W H

    1998-07-06

    The performance of the National Ignition Facility (NIF), especially in terms of laser focusability, will be determined by several key factors. One of these key factors is the optical specification for the thousands of large aperture optics that will comprise the 192 beamlines. We have previously reported on the importance of the specification of the power spectral density (PSD) on NIF performance. Recently, we have been studying the importance of long spatial wavelength (>33 mm) phase errors on focusability. We have concluded that the preferred metric for determining the impact of these long spatial wavelength phase errors is the rms phase gradient. In this paper, we outline the overall approach to NIF optical specifications, detail the impact of the rms phase gradient on NIF focusability, discuss its trade-off with the PSD in determining the spot size and review measurements of optics similar to those to be manufactured for NIF.

  9. Proposal for Cherenkov Time of Flight Technique with Picosecond Resolution

    SciTech Connect

    S. Majewski; A. Margaryan; L. Tang

    2005-08-05

    A new particle identification device for Jlab 12 GeV program is proposed. It is based on the measurement of time information obtained by means of a new photon detector and time measuring concept. The expected time measurement precision for the Cherenkov time-of-flight detector is about or less than 10 picosecond for Cherenkov radiators with lengths less than 50 cm.

  10. 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).

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

    NASA Image and Video Library

    1994-09-15

    STS064-76-035 (15 Sept. 1994) --- Backdropped against the darkness of space, the Shuttle Pointed Autonomous Research Tool for Astronomy 201 (SPARTAN-201) satellite is lined up with the space shuttle Discovery's Remote Manipulator System (RMS) arm for re-capture. The free-flying spacecraft had remained some 40 miles away from Discovery for over two days. Photo credit: NASA or National Aeronautics and Space Administration

  12. 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).

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

    NASA Image and Video Library

    1985-12-01

    61B-102-022 (1 Dec 1985) --- 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. The frame was exposed with a negative-equipped camera held by Astronaut Sherwood C. Spring, who was also on the EVA-task.

  14. RMS end effector waiting for command and SPAS-01 nearby

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The end effector of the remote manipulator system (RMS) appears to be waiting for its next command at the top of this frame and the Shuttle pallet satellite (SPAS-01), in its free flying mode, appears nearby. The three letters legible on the SPAS stand for Messerschmitt-Boelkow-Blohm Gmbit, a West German firm. The earth's horizon is visible at the bottom of the frame.

  15. Time stamping of single optical photons with 10 ns resolution

    DOE PAGES

    Chakaberia, Irakli; Cotlet, Mircea; Fisher-Levine, Merlin; ...

    2017-05-08

    High spatial and temporal resolution are key features for many modern applications, e.g. mass spectrometry, probing the structure of materials via neutron scattering, studying molecular structure, etc. Fast imaging also provides the capability of coincidence detection, and the further addition of sensitivity to single optical photons with the capability of timestamping them further broadens the field of potential applications. Here, photon counting is already widely used in X-ray imaging, where the high energy of the photons makes their detection easier.

  16. 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.

  17. Space-time super-resolution using graph-cut optimization.

    PubMed

    Mudenagudi, Uma; Banerjee, Subhashis; Kalra, Prem Kumar

    2011-05-01

    We address the problem of super-resolution—obtaining high-resolution images and videos from multiple low-resolution inputs. The increased resolution can be in spatial or temporal dimensions, or even in both. We present a unified framework which uses a generative model of the imaging process and can address spatial super-resolution, space-time super-resolution, image deconvolution, single-image expansion, removal of noise, and image restoration. We model a high-resolution image or video as a Markov random field and use maximum a posteriori estimate as the final solution using graph-cut optimization technique. We derive insights into what super-resolution magnification factors are possible and the conditions necessary for super-resolution. We demonstrate spatial super-resolution reconstruction results with magnifications higher than predicted limits of magnification. We also formulate a scheme for selective super-resolution reconstruction of videos to obtain simultaneous increase of resolutions in both spatial and temporal directions. We show that it is possible to achieve space-time magnification factors beyond what has been suggested in the literature by selectively applying super-resolution constraints. We present results on both synthetic and real input sequences.

  18. 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

  19. Absolute Calibration of Si iRMs used for Measurements of Si Paleo-nutrient proxies

    NASA Astrophysics Data System (ADS)

    Vocke, R. D., Jr.; Rabb, S. A.

    2016-12-01

    Silicon isotope variations (reported as δ30Si and δ29Si, relative to NBS28) in silicic acid dissolved in ocean waters, in biogenic silica and in diatoms are extremely informative paleo-nutrient proxies. The resolution and comparability of such measurements depend on the quality of the isotopic Reference Materials (iRMs) defining the delta scale. We report new absolute Si isotopic measurements on the iRMs NBS28 (RM 8546 - Silica Sand), Diatomite, and Big Batch using the Avogadro measurement approach and comparing them with prior assessments of these iRMs. The Avogadro Si measurement technique was developed by the German Physikalish-Technische Bundesanstalt (PTB) to provide a precise and highly accurate method to measure absolute isotopic ratios in highly enriched 28Si (99.996%) material. These measurements are part of an international effort to redefine the kg and mole based on the Planck constant h and the Avogadro constant NA, respectively (Vocke et al., 2014 Metrologia 51, 361, Azuma et al., 2015 Metrologia 52 360). This approach produces absolute Si isotope ratio data with lower levels of uncertainty when compared to the traditional "Atomic Weights" method of absolute isotope ratio measurement calibration. This is illustrated in Fig. 1 where absolute Si isotopic measurements on SRM 990, separated by 40+ years of advances in instrumentation, are compared. The availability of this new technique does not say that absolute Si isotopic ratios are or ever will be better for normal Si isotopic measurements when seeking isotopic variations in nature, because they are not. However, by determining the absolute isotopic ratios of all the Si iRM scale artifacts, such iRMs become traceable to the metric system (SI); thereby automatically conferring on all the artifact-based δ30Si and δ29Si measurements traceability to the base SI unit, the mole. Such traceability should help reduce the potential of bias between different iRMs and facilitate the replacement of delta

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

    NASA Image and Video Library

    1992-11-01

    STS052-71-057 (22 Oct-1 Nov 1992) --- This 70mm frame, photographed with a handheld Hasselblad camera aimed through Columbia's aft flight deck windows, captures the operation of the Space Vision System (SVS) experiment above the cargo bay. Target dots have been placed on the Canadian Target Assembly (CTA), a small satellite, in the grasp of the Canadian-built remote manipulator system (RMS) arm. SVS utilized a Shuttle TV camera to monitor the dots strategically arranged on the satellite, to be tracked. As the satellite moved via the arm, 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 displayed 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 in the frame is the U.S. Microgravity Payload (USMP-01).

  1. A VLSI Processor Design of Real-Time Data Compression for High-Resolution Imaging Radar

    NASA Technical Reports Server (NTRS)

    Fang, W.

    1994-01-01

    For the high-resolution imaging radar systems, real-time data compression of raw imaging data is required to accomplish the science requirements and satisfy the given communication and storage constraints. The Block Adaptive Quantizer (BAQ) algorithm and its associated VLSI processor design have been developed to provide a real-time data compressor for high-resolution imaging radar systems.

  2. Analysis of decade-long time series of GPS-based polar motion estimates at 15-min temporal resolution

    NASA Astrophysics Data System (ADS)

    Sibois, Aurore E.; Desai, Shailen D.; Bertiger, Willy; Haines, Bruce J.

    2017-08-01

    We present results from the generation of 10-year-long continuous time series of the Earth's polar motion at 15-min temporal resolution using Global Positioning System ground data. From our results, we infer an overall noise level in our high-rate polar motion time series of 60 μas (RMS). However, a spectral decomposition of our estimates indicates a noise floor of 4 μas at periods shorter than 2 days, which enables recovery of diurnal and semidiurnal tidally induced polar motion. We deliberately place no constraints on retrograde diurnal polar motion despite its inherent ambiguity with long-period nutation. With this approach, we are able to resolve damped manifestations of the effects of the diurnal ocean tides on retrograde polar motion. As such, our approach is at least capable of discriminating between a historical background nutation model that excludes the effects of the diurnal ocean tides and modern models that include those effects. To assess the quality of our polar motion solution outside of the retrograde diurnal frequency band, we focus on its capability to recover tidally driven and non-tidal variations manifesting at the ultra-rapid (intra-daily) and rapid (characterized by periods ranging from 2 to 20 days) periods. We find that our best estimates of diurnal and semidiurnal tidally induced polar motion result from an approach that adopts, at the observation level, a reasonable background model of these effects. We also demonstrate that our high-rate polar motion estimates yield similar results to daily-resolved polar motion estimates, and therefore do not compromise the ability to resolve polar motion at periods of 2-20 days.

  3. Analysis of decade-long time series of GPS-based polar motion estimates at 15-min temporal resolution

    NASA Astrophysics Data System (ADS)

    Sibois, Aurore E.; Desai, Shailen D.; Bertiger, Willy; Haines, Bruce J.

    2017-02-01

    We present results from the generation of 10-year-long continuous time series of the Earth's polar motion at 15-min temporal resolution using Global Positioning System ground data. From our results, we infer an overall noise level in our high-rate polar motion time series of 60 μas (RMS). However, a spectral decomposition of our estimates indicates a noise floor of 4 μas at periods shorter than 2 days, which enables recovery of diurnal and semidiurnal tidally induced polar motion. We deliberately place no constraints on retrograde diurnal polar motion despite its inherent ambiguity with long-period nutation. With this approach, we are able to resolve damped manifestations of the effects of the diurnal ocean tides on retrograde polar motion. As such, our approach is at least capable of discriminating between a historical background nutation model that excludes the effects of the diurnal ocean tides and modern models that include those effects. To assess the quality of our polar motion solution outside of the retrograde diurnal frequency band, we focus on its capability to recover tidally driven and non-tidal variations manifesting at the ultra-rapid (intra-daily) and rapid (characterized by periods ranging from 2 to 20 days) periods. We find that our best estimates of diurnal and semidiurnal tidally induced polar motion result from an approach that adopts, at the observation level, a reasonable background model of these effects. We also demonstrate that our high-rate polar motion estimates yield similar results to daily-resolved polar motion estimates, and therefore do not compromise the ability to resolve polar motion at periods of 2-20 days.

  4. 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

  5. A comprehensive characterization of the time resolution of the Philips Digital Photon Counter

    NASA Astrophysics Data System (ADS)

    Brunner, S. E.; Gruber, L.; Hirtl, A.; Suzuki, K.; Marton, J.; Schaart, D. R.

    2016-11-01

    Photodetectors with excellent time resolution are becoming increasingly important in many applications in medicine, high energy- and nuclear physics applications, biology, and material science. Silicon photomultipliers (SiPM) are a novel class of solid-state photodetectors with good timing properties. While the time resolution of analog SiPMs has been analyzed by many groups, the time resolution of the digital photon counter (DPC) developed by Philips has not yet been fully characterised. Here, the timing capabilities of the DPC are studied using a femtosecond laser. The time resolution is determined for complete dies, single pixels, and individual single photon avalanche diodes (SPADs). The measurements cover a broad dynamic range, from intense illumination down to the single-photon level, and were performed at various temperatures between 0°C and 20°C. The measured single photon time resolution (SPTR) ranges from 101 ps FWHM for the DPC3200 sensor pixel to 247 ps FWHM for the DPC6400 sensor die. An extensive study of the single-SPAD time resolution, ranging from single photon to very high laser intensities (~1000 photons per pulse), yielded a time resolution of 48 ps FWHM at the single-photon level.

  6. 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.

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

    NASA Image and Video Library

    1991-04-07

    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.

  8. 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.

  9. 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.

  10. 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.

  11. SPIFEX at work on end of RMS arm

    NASA Image and Video Library

    1994-09-10

    STS064-72-093 (10 Sept. 1994) --- 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 was exposed with a 70mm handheld Hasselblad camera from inside the space shuttle Discovery's crew cabin. Photo credit: NASA or National Aeronautics and Space Administration

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

    NASA Image and Video Library

    1994-09-12

    STS064-05-028 (9-20 Sept. 1994) --- 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 several tasks performed by the crew during the almost 11-day mission. Those tasks included the release and retrieval of the free-flying Shuttle Pointed Autonomous Research Tool For Astronomy 201 (SPARTAN 201), a six-hour spacewalk and the Shuttle Plume Impingement Flight Experiment (SPIFEX). Photo credit: NASA or National Aeronautics and Space Administration

  13. A picosecond resolution Time Digitizer for laser ranging

    NASA Technical Reports Server (NTRS)

    Turko, B.

    1978-01-01

    The Time Digitizer capable of covering a range of 0.34 sec in 9.76 psec increments is described. The time interval between a pair of start-stop pulses is digitized coarsely in 20 nsec periods by a very accurate 50 MHz reference clock. The residual fractions of a clock period at the start and the stop end of the measured interval are stretched in two interpolators and digitized in 9.76 psec increments. An equivalent digitizing frequency of 102.4 GHz is thus achieved. The digitizer is built in a minicrate and communicates via a standard crate controller. It is intended for use in the laser ranging between ground stations and the Laser Geodetic Satellite (LAGEOS). It is shown that the distribution in any two adjacent 9.76 psec channels of a small number of identical test time intervals is essentially binomial. The performance of the digitizer and test results are given.

  14. Real-time flutter identification with close mode resolution

    NASA Technical Reports Server (NTRS)

    Roy, R. H.; Walker, R. A.; Gilyard, G. B.

    1986-01-01

    Real-time flutter prediction including close modes can be effectively estimated from turbulence or on-board excitation with an Extended Kalman Filter (EKF) approach. A physically based model form enables prediction of the damping rate as well as damping, giving a time to instability estimate with its variance. The approach is recursive and can operate asynchronously to drop data outliers and hence is quite robust. Its speed is reasonable for on-line application but can also be used effectively as an off-line analysis tool for application to any modal testing situation.

  15. Timing resolution of scintillation-detector systems: a Monte Carlo analysis

    PubMed Central

    Choong, Woon-Seng

    2010-01-01

    Recent advancements in fast scintillating materials and fast photomultiplier tubes (PMTs) have stimulated renewed interest in time-of-flight (TOF) positron emission tomography (PET). It is well known that the improvement in the timing resolution in PET can significantly reduce the noise variance in the reconstructed image resulting in improved image quality. In order to evaluate the timing performance of scintillation detectors used in TOF PET, we use a Monte Carlo analysis to model the physical processes (crystal geometry, crystal surface finish, scintillator rise time, scintillator decay time, photoelectron yield, PMT transit time spread, PMT single-electron response, amplifier response, and time pick-off method) that can contribute to the timing resolution of scintillation-detector systems. In the Monte Carlo analysis, the photoelectron emissions are modeled by a rate function, which is used to generate the photoelectron time points. The rate function, which is simulated using Geant4, represents the combined intrinsic light emissions of the scintillator and the subsequent light transport through the crystal. The PMT output signal is determined by the superposition of the PMT single-electron response resulting from the photoelectron emissions. The transit time spread and the single-electron gain variation of the PMT are modeled in the analysis. Three practical time pick-off methods are considered in the analysis. Statistically, the best timing resolution is achieved with the first photoelectron timing. The calculated timing resolution suggests that a leading edge discriminator gives better timing performance than a constant fraction discriminator and produces comparable results when a 2-threshold or 3-threshold discriminator is used. For a typical PMT, the effect of detector noise on the timing resolution is negligible. The calculated timing resolution is found to improve with increasing mean photoelectron yield, decreasing scintillator decay time, and decreasing

  16. High time-resolution imaging with the MAMA detector systems

    NASA Technical Reports Server (NTRS)

    Morgan, Jeffrey S.; Timothy, J. Gethyn; Smith, Andrew M.; Hill, Bob; Kasle, David B.

    1990-01-01

    Current uses of the MAMA detector which utilize the photon time-tagging capabilities of these detectors are reported. These applications currently include image stabilization by means of post-processing corrections of platform drift and speckle interferometry. The initial results of a sounding rocket experiment to obtain UV images of NGC 6240 and results from speckle interferometry of Neptune's moon Triton are presented.

  17. The lower timing resolution bound for scintillators with non-negligible optical photon transport time in time-of-flight PET

    PubMed Central

    Vinke, Ruud; Olcott, Peter D.; Cates, Joshua W.; Levin, Craig S.

    2014-01-01

    In this work, a method is presented that can calculate the lower bound of the timing resolution for large scintillation crystals with non-negligible photon transport. Hereby, the timing resolution bound can directly be calculated from Monte Carlo generated arrival times of the scintillation photons. This method extends timing resolution bound calculations based on analytical equations, as crystal geometries can be evaluated that do not have closed form solutions of arrival time distributions. The timing resolution bounds are calculated for an exemplary 3 × 3 × 20 mm3 LYSO crystal geometry, with scintillation centers exponentially spread along the crystal length as well as with scintillation centers at fixed distances from the photosensor. Pulse shape simulations further show that analog photosensors intrinsically operate near the timing resolution bound, which can be attributed to the finite single photoelectron pulse rise time. PMID:25255807

  18. 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.

  19. Real-time high-velocity resolution color Doppler OCT

    NASA Astrophysics Data System (ADS)

    Westphal, Volker; Yazdanfar, Siavash; Rollins, Andrew M.; Izatt, Joseph A.

    2001-05-01

    Color Doppler optical coherence tomography (CDOCT), also called Optical Doppler Tomography) is a noninvasive optical imaging technique, which allows for micron-scale physiological flow mapping simultaneous with morphological OCT imaging. Current systems for real-time endoscopic optical coherence tomography (EOCT) would be enhanced by the capability to visualize sub-surface blood flow for applications in early cancer diagnosis and the management of bleeding ulcers. Unfortunately, previous implementations of CDOCT have either been sufficiently computationally expensive (employing Fourier or Hilbert transform techniques) to rule out real-time imaging of flow, or have been restricted to imaging of excessively high flow velocities when used in real time. We have developed a novel Doppler OCT signal-processing strategy capable of imaging physiological flow rates in real time. This strategy employs cross-correlation processing of sequential A-scans in an EOCT image, as opposed to autocorrelation processing as described previously. To measure Doppler shifts in the kHz range using this technique, it was necessary to stabilize the EOCT interferometer center frequency, eliminate parasitic phase noise, and to construct a digital cross correlation unit able to correlate signals of megahertz bandwidth by a fixed lag of up to a few ms. The performance of the color Doppler OCT system was demonstrated in a flow phantom, demonstrating a minimum detectable flow velocity of ~0.8 mm/s at a data acquisition rate of 8 images/second (with 480 A-scans/image) using a handheld probe. Dynamic flow as well as using it freehanded was shown. Flow was also detectable in a phantom in combination with a clinical usable endoscopic probe.

  20. 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.

  1. 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)

  2. 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.

  3. Quantitative Characterization of Super-Resolution Infrared Imaging Based on Time-Varying Focal Plane Coding

    NASA Astrophysics Data System (ADS)

    Wang, X.; Yuan, Y.; Zhang, J.; Chen, Y.; Cheng, Y.

    2014-10-01

    High resolution infrared image has been the goal of an infrared imaging system. In this paper, a super-resolution infrared imaging method using time-varying coded mask is proposed based on focal plane coding and compressed sensing theory. The basic idea of this method is to set a coded mask on the focal plane of the optical system, and the same scene could be sampled many times repeatedly by using time-varying control coding strategy, the super-resolution image is further reconstructed by sparse optimization algorithm. The results of simulation are quantitatively evaluated by introducing the Peak Signal-to-Noise Ratio (PSNR) and Modulation Transfer Function (MTF), which illustrate that the effect of compressed measurement coefficient r and coded mask resolution m on the reconstructed image quality. Research results show that the proposed method will promote infrared imaging quality effectively, which will be helpful for the practical design of new type of high resolution ! infrared imaging systems.

  4. Application of The Hydrology Lab Research Modeling System (hl-rms) For Large Headwater Catchments

    NASA Astrophysics Data System (ADS)

    Koren, V.; Smith, M.; Reed, S.; Zhang, Z.

    features. The first version consists of the Sacramento Soil Moisture Accounting (SAC-SMA) conceptual model applied on a regular spatial grid and kinematic hillslope and channel routing models. However, other runoff/routing models can be easily incorporated into this structure. Initial (a `priori) parameter grids are generated over large regions of the United States based on high resolution soil-vegetation and DEM data. Although these parameters may be 'non-optimal' for specific catchments, they provide reasonable ref- erence simulations prior to calibration of distributed parameters. Some approaches of a `priori parameter adjustments are being developed. A few options are now available 1 which are based on combined analyses of distributed basin properties and an integrated basin response at an outlet: 1) Scale/replace a `priori parameter grids using results of lumped or semi-distributed calibration of rainfall-runoff component; 2) Adjust rout- ing timing based on an outlet hydrograph analysis; and 3) Generate spatially variable channel shape and roughness parameters from flow measurement information and ge- omorphological properties at each grid cell. HL-RMS application and test results for a few headwater catchments will be discussed. 2

  5. A 30 ps Timing Resolution for Single Photons with Multi-pixel Burle MCP-PMT

    SciTech Connect

    Va'vra, J.; Benitez, J.; Coleman, J.; Leith, D.W.G.S.; Mazaheri, G.; Ratcliff, B.; Schwiening, J.; /SLAC

    2006-07-05

    We have achieved {approx}30 psec single-photoelectron and {approx}12ps for multi-photoelectron timing resolution with a new 64 pixel Burle MCP-PMT with 10 micron microchannel holes. We have also demonstrated that this detector works in a magnetic field of 15kG, and achieved a single-photoelectron timing resolution of better than 60 psec. The study is relevant for a new focusing DIRC RICH detector for particle identification at future Colliders such as the super B-factory or ILC, and for future TOF techniques. This study shows that a highly pixilated MCP-PMT can deliver excellent timing resolution.

  6. 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.

  7. Real time orthorectification of high resolution airborne pushbroom imagery

    NASA Astrophysics Data System (ADS)

    Reguera-Salgado, Javier; Martin-Herrero, Julio

    2011-11-01

    Advanced architectures have been proposed for efficient orthorectification of digital airborne camera images, including a system based on GPU processing and distributed computing able to geocorrect three digital still aerial photographs per second. Here, we address the computationally harder problem of geocorrecting image data from airborne pushbroom sensors, where each individual image line has associated its own camera attitude and position parameters. Using OpenGL and CUDA interoperability and projective texture techniques, originally developed for fast shadow rendering, image data is projected onto a Digital Terrain Model (DTM) as if by a slide projector placed and rotated in accordance with GPS position and inertial navigation (IMU) data. Each line is sequentially projected onto the DTM to generate an intermediate frame, consisting of a unique projected line shaped by the DTM relief. The frames are then merged into a geometrically corrected georeferenced orthoimage. To target hyperband systems, avoiding the high dimensional overhead, we deal with an orthoimage of pixel placeholders pointing to the raw image data, which are then combined as needed for visualization or processing tasks. We achieved faster than real-time performance in a hyperspectral pushbroom system working at a line rate of 30 Hz with 200 bands and 1280 pixel wide swath over a 1 m grid DTM, reaching a minimum processing speed of 356 lines per second (up to 511 lps), over eleven (up to seventeen) times the acquisition rate. Our method also allows the correction of systematic GPS and/or IMU biases by means of 3D user interactive navigation.

  8. Coherent diffractive imaging of time-evolving samples with improved temporal resolution

    SciTech Connect

    Ulvestad, A.; Tripathi, A.; Hruszkewycz, S. O.; Cha, W.; Wild, S. M.; Stephenson, G. B.; Fuoss, P. H.

    2016-05-19

    Bragg coherent x-ray diffractive imaging is a powerful technique for investigating dynamic nanoscale processes in nanoparticles immersed in reactive, realistic environments. Its temporal resolution is limited, however, by the oversampling requirements of three-dimensional phase retrieval. Here, we show that incorporating the entire measurement time series, which is typically a continuous physical process, into phase retrieval allows the oversampling requirement at each time step to be reduced, leading to a subsequent improvement in the temporal resolution by a factor of 2-20 times. The increased time resolution will allow imaging of faster dynamics and of radiation-dose-sensitive samples. Furthermore, this approach, which we call "chrono CDI," may find use in improving the time resolution in other imaging techniques.

  9. Coherent diffractive imaging of time-evolving samples with improved temporal resolution

    SciTech Connect

    Ulvestad, A.; Tripathi, A.; Hruszkewycz, S. O.; Cha, W.; Wild, S. M.; Stephenson, G. B.; Fuoss, P. H.

    2016-05-19

    Bragg coherent x-ray diffractive imaging is a powerful technique for investigating dynamic nanoscale processes in nanoparticles immersed in reactive, realistic environments. Its temporal resolution is limited, however, by the oversampling requirements of three-dimensional phase retrieval. Here, we show that incorporating the entire measurement time series, which is typically a continuous physical process, into phase retrieval allows the oversampling requirement at each time step to be reduced, leading to a subsequent improvement in the temporal resolution by a factor of 2-20 times. The increased time resolution will allow imaging of faster dynamics and of radiation-dose-sensitive samples. This approach, which we call "chrono CDI," may find use in improving the time resolution in other imaging techniques.

  10. Coherent diffractive imaging of time-evolving samples with improved temporal resolution

    DOE PAGES

    Ulvestad, A.; Tripathi, A.; Hruszkewycz, S. O.; ...

    2016-05-19

    Bragg coherent x-ray diffractive imaging is a powerful technique for investigating dynamic nanoscale processes in nanoparticles immersed in reactive, realistic environments. Its temporal resolution is limited, however, by the oversampling requirements of three-dimensional phase retrieval. Here, we show that incorporating the entire measurement time series, which is typically a continuous physical process, into phase retrieval allows the oversampling requirement at each time step to be reduced, leading to a subsequent improvement in the temporal resolution by a factor of 2-20 times. The increased time resolution will allow imaging of faster dynamics and of radiation-dose-sensitive samples. Furthermore, this approach, which wemore » call "chrono CDI," may find use in improving the time resolution in other imaging techniques.« less

  11. Coherent diffractive imaging of time-evolving samples with improved temporal resolution

    NASA Astrophysics Data System (ADS)

    Ulvestad, A.; Tripathi, A.; Hruszkewycz, S. O.; Cha, W.; Wild, S. M.; Stephenson, G. B.; Fuoss, P. H.

    2016-05-01

    Bragg coherent x-ray diffractive imaging is a powerful technique for investigating dynamic nanoscale processes in nanoparticles immersed in reactive, realistic environments. Its temporal resolution is limited, however, by the oversampling requirements of three-dimensional phase retrieval. Here, we show that incorporating the entire measurement time series, which is typically a continuous physical process, into phase retrieval allows the oversampling requirement at each time step to be reduced, leading to a subsequent improvement in the temporal resolution by a factor of 2-20 times. The increased time resolution will allow imaging of faster dynamics and of radiation-dose-sensitive samples. This approach, which we call "chrono CDI," may find use in improving the time resolution in other imaging techniques.

  12. 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.

  13. 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

  14. High resolution time-of-flight measurements in small and large scintillation counters

    NASA Astrophysics Data System (ADS)

    D'Agostini, G.; Marini, G.; Martellotti, G.; Massa, F.; Rambaldi, A.; Sciubba, A.

    1981-06-01

    In a test run, the experimental time-of-flight resolution was measured for several different scintillation counters of small (10 × 5 cm 2) and large (100 × 15 cm 2 and 75 × 25 cm 2) area. The design characteristics were decided on the basis of theoretical Monte Carlo calculations. We report results using twisted, fish-tail, and rectangular light-guides and different types of scintillator (NE114 and PILOT U). Time resolution up to ˜130-150 ps fwhm for the small counters and up to ˜280-300 ps fwhm for the large counters were obtained. The spatial resolution from time measurements in the large counters is also reported. The results of Monte Carlo calculations on the type of scintillator, the shape and dimensions of the light-guides, and the nature of the external wrapping surfaces — to be used in order to optimize the time resolution — are also summarized.

  15. Time resolution of a 1-inch cylindrical CeBr3 crystal at 60Co energies

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    We have measured time resolutions of a cylindrical CeBr3 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 60Co energies was obtained for the CeBr3 crystal coupled to the Hamamatsu PMT. This result is comparable to the resolution of 107 ps reported for a LaBr3(Ce) crystal of the same size. For the coupling of the CeBr3 scintillator to the Photonis PMT we got the time resolution of 146(2) ps.

  16. Analytical model of SiPM time resolution and order statistics with crosstalk

    NASA Astrophysics Data System (ADS)

    Vinogradov, S.

    2015-07-01

    Time resolution is the most important parameter of photon detectors in a wide range of time-of-flight and time correlation applications within the areas of high energy physics, medical imaging, and others. Silicon photomultipliers (SiPM) have been initially recognized as perfect photon-number-resolving detectors; now they also provide outstanding results in the scintillator timing resolution. However, crosstalk and afterpulsing introduce false secondary non-Poissonian events, and SiPM time resolution models are experiencing significant difficulties with that. This study presents an attempt to develop an analytical model of the timing resolution of an SiPM taking into account statistics of secondary events resulting from a crosstalk. Two approaches have been utilized to derive an analytical expression for time resolution: the first one based on statistics of independent identically distributed detection event times and the second one based on order statistics of these times. The first approach is found to be more straightforward and "analytical-friendly" to model analog SiPMs. Comparisons of coincidence resolving times predicted by the model with the known experimental results from a LYSO:Ce scintillator and a Hamamatsu MPPC are presented.

  17. Reliability, Maintainability, and Supportability (RMS) education in engineering schools

    NASA Astrophysics Data System (ADS)

    Hurst, Gregory T.; Kinter, Barry N.

    1992-12-01

    The purpose of this research is to show how engineering schools, as a whole, perceive the role of reliability, maintainability, and supportability in the engineering field. This includes the degree to which these concepts are included in their curricula, whether industry recruiters look for reliability, maintainability, and supportability training when they visit college campuses and to what degree college faculties are teaching reliability, maintainability, and supportability. This is done through research of existing literature and the analysis of data from a survey completed by engineering schools. General analyses are presented of the overall responses and detailed analysis of contrasts and similarities between the responses from private and public institutions are presented. Based upon the knowledge gained in conducting this research, conclusions on the state of RMS education in engineering institutions are forwarded.

  18. Dependence of Hurricane intensity and structures on vertical resolution and time-step size

    NASA Astrophysics Data System (ADS)

    Zhang, Da-Lin; Wang, Xiaoxue

    2003-09-01

    In view of the growing interests in the explicit modeling of clouds and precipitation, the effects of varying vertical resolution and time-step sizes on the 72-h explicit simulation of Hurricane Andrew (1992) are studied using the Pennsylvania State University/National Center for Atmospheric Research (PSU/NCAR) mesoscale model (i.e., MM5) with the finest grid size of 6 km. It is shown that changing vertical resolution and time-step size has significant effects on hurricane intensity and inner-core cloud/precipitation, but little impact on the hurricane track. In general, increasing vertical resolution tends to produce a deeper storm with lower central pressure and stronger three-dimensional winds, and more precipitation. Similar effects, but to a less extent, occur when the time-step size is reduced. It is found that increasing the low-level vertical resolution is more efficient in intensifying a hurricane, whereas changing the upper-level vertical resolution has little impact on the hurricane intensity. Moreover, the use of a thicker surface layer tends to produce higher maximum surface winds. It is concluded that the use of higher vertical resolution, a thin surface layer, and smaller time-step sizes, along with higher horizontal resolution, is desirable to model more realistically the intensity and inner-core structures and evolution of tropical storms as well as the other convectively driven weather systems.

  19. Astronauts Sally Ride and Terry Hart prepare for RMS training for STS-2

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Astronauts Sally Ride and Terry Hart prepare for remote manipulator system (RMS) training for STS-2 in bldg 9A. Views include Ride, Hart and Robert R. Kain of the Flight Activites Branch reviewing procedures for RMS training (34262); Ride and Hart stand beside the RMS control center looking down at the payload bay mock-up (34263).

  20. Astronauts Sally Ride and Terry Hart prepare for RMS training for STS-2

    NASA Image and Video Library

    1981-07-17

    Astronauts Sally Ride and Terry Hart prepare for remote manipulator system (RMS) training for STS-2 in bldg 9A. Views include Ride, Hart and Robert R. Kain of the Flight Activites Branch reviewing procedures for RMS training (34262); Ride and Hart stand beside the RMS control center looking down at the payload bay mock-up (34263).

  1. Astronauts Sally Ride and Terry Hart prepare for RMS training for STS-2

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Astronauts Sally Ride and Terry Hart prepare for remote manipulator system (RMS) training for STS-2 in bldg 9A. Views include Ride, Hart and Robert R. Kain of the Flight Activites Branch reviewing procedures for RMS training (34262); Ride and Hart stand beside the RMS control center looking down at the payload bay mock-up (34263).

  2. Focal plane resolution and overlapped array time delay and integrate imaging

    NASA Astrophysics Data System (ADS)

    Grycewicz, Thomas J.; Cota, Stephen A.; Lomheim, Terrence S.; Kalman, Linda S.

    2010-06-01

    In this paper we model sub-pixel image registration for a generic earth-observing satellite system with a focal plane using two offset time delay and integrate (TDI) arrays in the focal plane to improve the achievable ground resolution over the resolution achievable with a single array. The modeling process starts with a high-resolution image as ground truth. The Parameterized Image Chain Analysis & Simulation Software (PICASSO) modeling tool is used to degrade the images to match the optical transfer function, sampling, and noise characteristics of the target system. The model outputs a pair of images with a separation close to the nominal half-pixel separation between the overlapped arrays. A registration estimation algorithm is used to measure the offset for image reconstruction. The two images are aligned and summed on a grid with twice the capture resolution. We compare the resolution in images between the inputs before overlap, the reconstructed image, and a simulation for the image which would have been captured on a focal plane with twice the resolution. We find the performance to always be better than the lower resolution baseline, and to approach the performance of the high-resolution array in the ideal case. We show that the overlapped array imager significantly outperforms both the conventional high- and low-resolution imagers in conditions with high image smear.

  3. 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.

  4. Spectral encoding based measurement of x-ray/optical relative delay to ~10 fs rms

    NASA Astrophysics Data System (ADS)

    Bionta, Mina R.; French, Doug; Cryan, James P.; Glownia, James M.; Hartmann, Nick; Nicholson, David J.; Baker, Kevin; Bostedt, Christoph; Cammarrata, Marco; Chollet, Matthieu; Ding, Yuantao; Fritz, David M.; Durbin, Steve M.; Feng, Yiping; Harmand, Marion; Fry, Alan R.; Kane, Daniel J.; Krzywinski, Jacek; Lemke, Henrik T.; Messerschmidt, Marc; Ratner, Daniel F.; Schorb, Sebastian; Toleikis, Sven; Zhu, Diling; White, William E.; Coffee, Ryan N.

    2012-10-01

    A recently demonstrated single-shot measurement of the relative delay between x-ray FEL pulses and optical laser pulses has now been improved to ~10 fs rms error and has successfully been demonstrated for both soft and hard x-ray pulses. It is based on x-ray induced step-like reduction in optical transmissivity of a semiconductor membrane (Si3N4). The transmissivity is probed by an optical continuum spanning 450 - 650 nm where spectral chirp provides a mapping of the step in spectrum to the arrival time of the x-ray pulse relative to the optical laser system.

  5. Astronaut Anna Fisher practices control of the RMS in a trainer

    NASA Image and Video Library

    1984-08-21

    S84-40162 (21 Aug. 1984) --- Astronaut Anna L. Fisher controls the Remote Manipulator System (RMS) arm from inside the "orbiter" as part of her training program in the Johnson Space Center's Shuttle Mock-up and Integration Laboratory. Dr. Fisher, one of three mission specialists for mission 51-A, is inside the cabin portion of a trainer called the Manipulatory Development Facility (MDF). She is able to operate the arm in conjunction with an air bearing floor and to log a great deal of rehearsal time for her flight, on which the retrieval of a low-orbiting communications satellite is planned. Photo credit: NASA

  6. 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...

  7. 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...

  8. 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.

  9. High Time Resolution Lightning Mapping Lightning Mapping Observations of a Small Thunderstorm during STEPS

    NASA Astrophysics Data System (ADS)

    Rison, W.; Krehbiel, P.; Thomas, R.; Hamlin, T.; Harlin, J.

    2001-12-01

    During the 2000 STEPS (Severe Thunderstorm Electrification and Precipitation Study) program, the New Mexico Tech Lightning Mapping Array (LMA) was operated in high time resolution mode [Rison et al., 2000] for several days. On July 11 a small thunderstorm formed over the northern part of the LMA network while the LMA was in this mode. The lightning mapping observations show that the electrical structure of the thunderstorm changed significantly during its lifetime. The electrical development of the storm as inferred from the lightning mapping observations will be presented. In high time resolution mode the LMA records the time of the strongest VHF radiation received in 10 μ s windows (compared to 100~μ s windows in normal time resolution mode). In high time resolution mode the LMA can produce significantly more detailed images of continuous radiation processes (such as stepped leaders, dart leaders and K-changes). Cloud-to-ground discharges examined in the July 11 storm show significant branching in stepped leaders, and there is sufficient detail in stepped and dart leaders and K-changes that good velocities for relatively fast leader processes (107 m/s) can be determined. [1ex] Rison, W., P. Krehbiel, R. Thomas, T. Hamlin, and J. Harlin, A Time-of-Arrival Lightning Mapping System with High Time Resolution, Abstract A52C-01, Fall Ann. Mtg. Amer. Geophys. Union, EOS, 81, p. F47, 2000.

  10. Influence of the sampling period and time resolution on the PM source apportionment: Study based on the high time-resolution data and long-term daily data

    NASA Astrophysics Data System (ADS)

    Tian, Yingze; Xiao, Zhimei; Wang, Haiting; Peng, Xing; Guan, Liao; Huangfu, Yanqi; Shi, Guoliang; Chen, Kui; Bi, Xiaohui; Feng, Yinchang

    2017-09-01

    When planning short-term and long-term measurement campaigns of particulate matter (PM), parameters such as sampling period, time resolution, sampling number, etc. are vital. To study their influence and to provide suggestion for the sampling plan of PM source apportionment (SA), ambient and synthetic speciated datasets (including a high time-resolution dataset and a long-term daily dataset) were studied. First, aiming at studying the sampling period required to generate representative and reliable results for SA, high time-resolution ambient samples were collected by online instruments in a megacity in China. Datasets with different sampling periods (four months, two months, one month, two weeks and one week) were modeled by the Positive Matrix Factorization (PMF). Compared with four month results, AAEs (percent absolute errors between true and estimated contributions) ranged from 11.2 to 27.2% (two months), 19.8-44.5% (one month), 21.0-45.9% (two weeks) and 23.9-44.6% (one week), indicating that divergence increased with decreasing sampling periods. To systematically evaluate this problem and investigate if the increasing time resolutions in a short period could enhance the modeling performance, synthetic datasets were constructed. Results revealed that a sufficient sampling period is required to ensure stable results; without sufficient sampling period, the contributions cannot be reliably estimated, even if the number of samples is large. Then, to explore the influence of variability absences, long-term daily datasets with various variability absences were apportioned and compared. The summed AAEs were 102.2% (no winter), 73.6% (no weekend), 138.7% (no weekday) and 165.6% (no autumn, winter or weekends). This general increase of AAEs can indicate that uncertainty enhanced with the increase in variability absences. When planning short-term measurement campaigns, except for number of samples, sampling period that involves sufficient source cycles has significant

  11. 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.

  12. The Time of Spontaneous Resolution of Monosymptomatic Nocturnal Enuresis (MNE) Is Familial.

    PubMed

    Oguz, Ural; Aykac, Aykut; Demirelli, Erhan; Sancak, Eyup Burak; Resorlu, Berkan; Sarikaya, Selcuk; Damar, Erman; Bozkurt, Omer Faruk; Ogreden, Ercan; Yalcin, Orhan

    2015-01-01

    To investigate whether or not the age of spontaneous resolution of monosymptomatic nocturnal enuresis (MNE) was familial. A questionnaire was administered to more than 1,500 people, and 100 appropriate participants were identified from four referral hospitals. We included the participants who had MNE and whose parents also had MNE with spontaneous resolution. Then the association between the spontaneous resolution time of MNE in parents and that in their children was investigated. The mean ages of spontaneous resolution were 10.7 (10-30 years), 9.4 (6-17 years) and 10.9 (6-18 years) in participants, their mothers and their fathers, respectively. According to the statistical analysis, there was a positive correlation between participants and both their mothers and fathers (p < 0.05). In addition, it was revealed that familial MNE history based on first- and second-degree relatives, in addition to their parents, was also associated with the increased spontaneous resolution age of MNE (p < 0.05). According to our results, gender and parents' education status were not statistically associated with the spontaneous resolution (p > 0.05). As a conclusion, the age of spontaneous resolution of MNE is familial. Although the exact reasons of spontaneous resolution still remain a mystery; further genetic investigations may be able to resolve this mystery. © 2015 S. Karger AG, Basel.

  13. KCa3.1 Modulates Neuroblast Migration Along the Rostral Migratory Stream (RMS) In Vivo

    PubMed Central

    Turner, Kathryn L.; Sontheimer, Harald

    2014-01-01

    From the subventricular zone (SVZ), neuronal precursor cells (NPCs), called neuroblasts, migrate through the rostral migratory stream (RMS) to become interneurons in the olfactory bulb (OB). Ion channels regulate neuronal migration during development, yet their role in migration through the adult RMS is unknown. To address this question, we utilized Nestin-CreERT2/R26R-YFP mice to fluorescently label neuroblasts in the adult. Patch-clamp recordings from neuroblasts reveal K+ currents that are sensitive to intracellular Ca2+ levels and blocked by clotrimazole and TRAM-34, inhibitors of intermediate conductance Ca2+-activated K+ (KCa3.1) channels. Immunolabeling and electrophysiology show KCa3.1 expression restricted to neuroblasts in the SVZ and RMS, but absent in OB neurons. Time-lapse confocal microscopy in situ showed inhibiting KCa3.1 prolonged the stationary phase of neuroblasts' saltatory migration, reducing migration speed by over 50%. Both migration and KCa3.1 currents could also be inhibited by blocking Ca2+ influx via transient receptor potential (TRP) channels, which, together with positive immunostaining for transient receptor potential canonical 1 (TRPC1), suggest that TRP channels are an important Ca2+ source modulating KCa3.1 activity. Finally, injecting TRAM-34 into Nestin-CreERT2/R26R-YFP mice significantly reduced the number of neuroblasts that reached the OB, suggesting an important role for KCa3.1 in vivo. These studies describe a previously unrecognized protein in migration of adult NPCs. PMID:23585521

  14. A simple technique for high resolution time domain phase noise measurement

    NASA Technical Reports Server (NTRS)

    Reinhardt, V. S.; Donahoe, T.

    1977-01-01

    A new time domain phase comparator is described. The device uses a novel technique to allow time domain phase measurements to be made with period and time interval counters without the use of offset reference oscillators. The device uses a single reference oscillator and allows measurements with a phase resolution greater than the noise floor of the reference. Data is presented showing a phase resolution of 0.02ps at 5 MHz with a crystal reference. The device has application in measuring the phase stability of systems where approximate phase quadrature can be maintained.

  15. Mesoscale scanning probe tips with subnanometer rms roughness

    NASA Astrophysics Data System (ADS)

    Xu, Dewei; Liechti, Kenneth M.; Ravi-Chandar, K.

    2007-07-01

    Surface smoothness of probe tips is critical for applications, such as measuring surface tension of various liquids, oscillatory hydration forces, and interfacial shear strengths from friction experiments. In this study we establish conditions for fabricating tips with smooth surfaces by controlling the electrochemical polishing process throughout the tip evolution rather than following the current practice of producing tips by the drop-off method. Polishing is conducted under a constant voltage, with the wire immersed below the nominal air/electrolyte interface by no more than one-half of the wire diameter and stopping the etching at different current levels. This process provides a tip radius range of approximately 100nmto5μm for a tungsten wire with a 0.2mm diameter. Alternatively, the wire can be placed above the nominal air/electrolyte interface but within the meniscus until the current drops to zero. In this case, the tip radii range from 5to50μm. In both cases, atomic force microscopy scans of these tips show that the surface rms roughness is about 0.3nm.

  16. Motor preparation is modulated by the resolution of the response timing information

    PubMed Central

    Carlsen, Anthony N.; MacKinnon, Colum D.

    2010-01-01

    In the present experiment, the temporal predictability of response time was systematically manipulated to examine its effect on the time course of motor pre-programming and release of the intended movement by an acoustic startle stimulus. Participants performed a ballistic right wrist extension task in four different temporal conditions: 1) a variable foreperiod simple RT task, 2) a fixed foreperiod simple RT task, 3) a low resolution countdown anticipation timing task, and 4) a high resolution anticipation-timing task. For each task, a startling acoustic stimulus (124 dB) was presented at several intervals prior to the “go” signal (“go” −150ms, −500 ms, and −1500 ms). Results from the startle trials showed that the time course of movement pre-programming was affected by the temporal uncertainty of the imperative “go” cue. These findings demonstrate that the resolution of the timing information regarding the response cue has a marked effect on the timing of movement preparation such that under conditions of low temporal resolution, participants plan the movement well in advance in accordance with the anticipated probability of onset of the cue, whereas movement preparation is delayed until less than 500 ms prior to response time when continuous temporal information is provided. PMID:20138165

  17. Assessment of lifetime resolution limits in time-resolved photoacoustic calorimetry vs. transducer frequencies: setting the stage for picosecond resolution.

    PubMed

    Schaberle, Fábio A; Rego Filho, Francisco de Assis M G; Reis, Luís A; Arnaut, Luis G

    2016-02-01

    Time-resolved photoacoustic calorimetry (PAC) gives access to lifetimes and energy fractions of reaction intermediates by deconvolution of the photoacoustic wave of a sample (E-wave) with that of the instrumental response (T-wave). The ability to discriminate between short lifetimes increases with transducer frequencies employed to detect the PAC waves. We investigate the lifetime resolution limits of PAC as a function of the transducer frequencies using the instrumental response obtained with the photoacoustic reference 2-hydroxybenzophenone in toluene or acetonitrile. The instrumental response was obtained for a set of transducers with central frequencies ranging from 0.5 MHz up to 225 MHz. The simulated dependence of the lifetime resolution with the transducer frequencies was anchored on experimental data obtained for the singlet state of naphthalene with a 2.25 MHz transducer. The shortest lifetime resolved with the 2.25 MHz transducer was 19 ns and our modelling of the transducer responses indicates that sub-nanosecond lifetimes of photoacoustic transients can be resolved with transducers of central frequencies above 100 MHz.

  18. Time-resolved diffraction and interference: Young's interference with photons of different energy as revealed by time resolution.

    PubMed

    Garcia, N; Saveliev, I G; Sharonov, M

    2002-05-15

    We present time-resolved diffraction and two-slit interference experiments using a streak camera as a detector for femtosecond pulses of photons. These experiments show how the diffraction pattern is built by adding frames of a few photons to each frame. It is estimated that after 300 photons the diffraction pattern emerges. With time resolution we can check the speed of light and put an upper limit of 2 ps at our resolution to the time for wave function collapse in the quantum measurement process. We then produce interference experiments with photons of different energies impinging on the slits, i.e. we know which photon impinges on each slit. We show that for poor time resolution, no interference is observed, but for high time resolution, we have interference that is revealed as beats of 100 GHz frequency. The condition for interference is that the two pulses should overlap spatially at the detector, even if the pulses have different energies but are generated from the same pulse of the laser. The interference seems to be in agreement with classical theory at first sight. However, closer study and analysis of the data show deviations in the visibility of the interference fringes and of their phase. These experiments are discussed in connection with quantum mechanics and it may be concluded that the time resolution provides new data for understanding the longstanding and continuing arguments on wave-particle duality initiated by Newton, Young, Fresnel, Planck and others. A thought experiment is presented in the appendix to try to distinguish the photons at the detector by making it sensitive to colour.

  19. 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.

  20. 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.

  1. The effect of resolution time of acute kidney injury on clinical outcomes

    PubMed Central

    Chavez-Iñiguez, J. S.; Garcia-Garcia, G.; Briseño-Ramirez, J.; Medina-Gonzalez, R.; Jimenez-Cornejo, M.

    2017-01-01

    Acute kidney injury (AKI) is a frequent and complex disease. It is not clearly defined whether its duration is related to adverse outcomes. We determined the effect of AKI resolution time on patient's clinical outcomes. A prospective cohort of hospitalized patients with AKI by AKI network (AKIN) creatinine criteria was included. Variables for prognosis and follow-up were analyzed. One hundred and thirteen patients were included in the study. Seventy-seven (68.1%) were males, mean age 55 years (range, 16–76 years), and 48 (42.5%) were diabetic. The most common cause of AKI was sepsis (31%). AKI resolution time ≤2 days and >2 days was seen in 47 (41.6%) and 66 (58.4%) of the cases, respectively. AKI resolution time >2 days was common in older patients (66.24 ± 17.6 year vs. 47.16 ± 12.32 year, P = 0.004), with the use of mechanical ventilation (27% vs. 4%, P = 0.02) and vasopressors (41% vs. 11%, P ≤ 0.01); it was associated with increased mortality (47% vs. 4%, P ≤ 0.01), and a discharge estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m2 (52% vs. 2%, P = 0.01), than in patients with resolution time ≤2 days. Survival rate was significantly worse in patients with a resolution time >2 days. By multivariate logistic step-wise regression analysis, AKI >2days, vasopressor use, and AKIN stage 2–3 were independently associated with higher mortality. AKI >2 days and vasopressor utilization were independently associated to an eGFR <60 ml/min/1.73 m2 at the time of discharge. We conclude that AKI resolution time >2 days is linked to adverse clinical outcomes. PMID:28356659

  2. High spatial resolution imaging for structural health monitoring based on virtual time reversal

    NASA Astrophysics Data System (ADS)

    Cai, Jian; Shi, Lihua; Yuan, Shenfang; Shao, Zhixue

    2011-05-01

    Lamb waves are widely used in structural health monitoring (SHM) of plate-like structures. Due to the dispersion effect, Lamb wavepackets will be elongated and the resolution for damage identification will be strongly affected. This effect can be automatically compensated by the time reversal process (TRP). However, the time information of the compensated waves is also removed at the same time. To improve the spatial resolution of Lamb wave detection, virtual time reversal (VTR) is presented in this paper. In VTR, a changing-element excitation and reception mechanism (CERM) rather than the traditional fixed excitation and reception mechanism (FERM) is adopted for time information conservation. Furthermore, the complicated TRP procedure is replaced by simple signal operations which can make savings in the hardware cost for recording and generating the time-reversed Lamb waves. After the effects of VTR for dispersive damage scattered signals are theoretically analyzed, the realization of VTR involving the acquisition of the transfer functions of damage detecting paths under step pulse excitation is discussed. Then, a VTR-based imaging method is developed to improve the spatial resolution of the delay-and-sum imaging with a sparse piezoelectric (PZT) wafer array. Experimental validation indicates that the damage scattered wavepackets of A0 mode in an aluminum plate are partly recompressed and focalized with their time information preserved by VTR. Both the single damage and the dual adjacent damages in the plate can be clearly displayed with high spatial resolution by the proposed VTR-based imaging method.

  3. Human factors assessment of conflict resolution aid reliability and time pressure in future air traffic control.

    PubMed

    Trapsilawati, Fitri; Qu, Xingda; Wickens, Chris D; Chen, Chun-Hsien

    2015-01-01

    Though it has been reported that air traffic controllers' (ATCos') performance improves with the aid of a conflict resolution aid (CRA), the effects of imperfect automation on CRA are so far unknown. The main objective of this study was to examine the effects of imperfect automation on conflict resolution. Twelve students with ATC knowledge were instructed to complete ATC tasks in four CRA conditions including reliable, unreliable and high time pressure, unreliable and low time pressure, and manual conditions. Participants were able to resolve the designated conflicts more accurately and faster in the reliable versus unreliable CRA conditions. When comparing the unreliable CRA and manual conditions, unreliable CRA led to better conflict resolution performance and higher situation awareness. Surprisingly, high time pressure triggered better conflict resolution performance as compared to the low time pressure condition. The findings from the present study highlight the importance of CRA in future ATC operations. Practitioner Summary: Conflict resolution aid (CRA) is a proposed automation decision aid in air traffic control (ATC). It was found in the present study that CRA was able to promote air traffic controllers' performance even when it was not perfectly reliable. These findings highlight the importance of CRA in future ATC operations.

  4. 30-ps time resolution with segmented scintillation counter for MEG II

    NASA Astrophysics Data System (ADS)

    Uchiyama, Y.; Boca, G.; Cattaneo, P. W.; De Gerone, M.; Gatti, F.; Nakao, M.; Nishimura, M.; Ootani, W.; Pizzigoni, G.; Rossella, M.; Simonetta, M.; Yoshida, K.

    2017-02-01

    A new timing detector has been developed to measure ∼50 MeV/c positrons with a time resolution of σt ≃ 30 ps in the MEG II experiment. The detector are segmented into 512 scintillation counters, each of which consists of 120 ×(40 or 50) × 5mm3 size BC-422 and two arrays of six AdvanSiD silicon photomultipliers. The single-counter resolutions are measured to be 70-80 ps. The counter layout is optimized to get the maximum number of hit counters (on average 9 for signal positrons). This multiple-counters measurement leads to a significant improvement in the time resolution down to 30 ps. Using the first one-fourth (128) counters, a pilot run was carried out using the MEG II beam of 7 ×107μ+ / s and the basic functionality was tested.

  5. 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.

  6. 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.

  7. Spatially detailed retrievals of spring phenology from single-season high-resolution image time series

    NASA Astrophysics Data System (ADS)

    Vrieling, Anton; Skidmore, Andrew K.; Wang, Tiejun; Meroni, Michele; Ens, Bruno J.; Oosterbeek, Kees; O'Connor, Brian; Darvishzadeh, Roshanak; Heurich, Marco; Shepherd, Anita; Paganini, Marc

    2017-07-01

    Vegetation indices derived from satellite image time series have been extensively used to estimate the timing of phenological events like season onset. Medium spatial resolution (≥250 m) satellite sensors with daily revisit capability are typically employed for this purpose. In recent years, phenology is being retrieved at higher resolution (≤30 m) in response to increasing availability of high-resolution satellite data. To overcome the reduced acquisition frequency of such data, previous attempts involved fusion between high- and medium-resolution data, or combinations of multi-year acquisitions in a single phenological reconstruction. The objectives of this study are to demonstrate that phenological parameters can now be retrieved from single-season high-resolution time series, and to compare these retrievals against those derived from multi-year high-resolution and single-season medium-resolution satellite data. The study focuses on the island of Schiermonnikoog, the Netherlands, which comprises a highly-dynamic saltmarsh, dune vegetation, and agricultural land. Combining NDVI series derived from atmospherically-corrected images from RapidEye (5 m-resolution) and the SPOT5 Take5 experiment (10m-resolution) acquired between March and August 2015, phenological parameters were estimated using a function fitting approach. We then compared results with phenology retrieved from four years of 30 m Landsat 8 OLI data, and single-year 100 m Proba-V and 250 m MODIS temporal composites of the same period. Retrieved phenological parameters from combined RapidEye/SPOT5 displayed spatially consistent results and a large spatial variability, providing complementary information to existing vegetation community maps. Retrievals that combined four years of Landsat observations into a single synthetic year were affected by the inclusion of years with warmer spring temperatures, whereas adjustment of the average phenology to 2015 observations was only feasible for a few pixels

  8. 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

  9. 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.

  10. All-passive pixel super-resolution of time-stretch imaging

    NASA Astrophysics Data System (ADS)

    Chan, Antony C. S.; Ng, Ho-Cheung; Bogaraju, Sharat C. V.; So, Hayden K. H.; Lam, Edmund Y.; Tsia, Kevin K.

    2017-03-01

    Based on image encoding in a serial-temporal format, optical time-stretch imaging entails a stringent requirement of state-of-the-art fast data acquisition unit in order to preserve high image resolution at an ultrahigh frame rate — hampering the widespread utilities of such technology. Here, we propose a pixel super-resolution (pixel-SR) technique tailored for time-stretch imaging that preserves pixel resolution at a relaxed sampling rate. It harnesses the subpixel shifts between image frames inherently introduced by asynchronous digital sampling of the continuous time-stretch imaging process. Precise pixel registration is thus accomplished without any active opto-mechanical subpixel-shift control or other additional hardware. Here, we present the experimental pixel-SR image reconstruction pipeline that restores high-resolution time-stretch images of microparticles and biological cells (phytoplankton) at a relaxed sampling rate (≈2-5 GSa/s)—more than four times lower than the originally required readout rate (20 GSa/s) — is thus effective for high-throughput label-free, morphology-based cellular classification down to single-cell precision. Upon integration with the high-throughput image processing technology, this pixel-SR time-stretch imaging technique represents a cost-effective and practical solution for large scale cell-based phenotypic screening in biomedical diagnosis and machine vision for quality control in manufacturing.

  11. Exploring the limiting timing resolution for large volume CZT detectors with waveform analysis.

    PubMed

    Meng, L J; He, Z

    2005-09-11

    This paper presents a study for exploring the limiting timing resolution that can be achieved with a large volume 3-D position sensitive CZT detector. The interaction timing information was obtained by fitting the measured cathode waveforms to pre-defined waveform models. We compared the results from using several different waveform models. Timing resolutions, of ~9.5 ns for 511 keV full-energy events and ~11.6 ns for all detected events with energy deposition above 250 keV, were achieved with a detailed modeling of the cathode waveform as a function of interaction location and energy deposition. This detailed modeling also allowed us to derive a theoretical lower bound for the error on estimated interaction timing. Both experimental results and theoretical predications matched well, which indicated that the best timing resolution achievable in the 1 cm(3) CZT detector tested is ~10 ns. It is also showed that the correlation between sampled amplitudes in cathode waveforms is an important limiting factor for the achievable timing resolution.

  12. Exploring the limiting timing resolution for large volume CZT detectors with waveform analysis

    PubMed Central

    Meng, L.J.; He, Z.

    2016-01-01

    This paper presents a study for exploring the limiting timing resolution that can be achieved with a large volume 3-D position sensitive CZT detector. The interaction timing information was obtained by fitting the measured cathode waveforms to pre-defined waveform models. We compared the results from using several different waveform models. Timing resolutions, of ~9.5 ns for 511 keV full-energy events and ~11.6 ns for all detected events with energy deposition above 250 keV, were achieved with a detailed modeling of the cathode waveform as a function of interaction location and energy deposition. This detailed modeling also allowed us to derive a theoretical lower bound for the error on estimated interaction timing. Both experimental results and theoretical predications matched well, which indicated that the best timing resolution achievable in the 1 cm3 CZT detector tested is ~10 ns. It is also showed that the correlation between sampled amplitudes in cathode waveforms is an important limiting factor for the achievable timing resolution. PMID:28260808

  13. All-passive pixel super-resolution of time-stretch imaging

    PubMed Central

    Chan, Antony C. S.; Ng, Ho-Cheung; Bogaraju, Sharat C. V.; So, Hayden K. H.; Lam, Edmund Y.; Tsia, Kevin K.

    2017-01-01

    Based on image encoding in a serial-temporal format, optical time-stretch imaging entails a stringent requirement of state-of-the-art fast data acquisition unit in order to preserve high image resolution at an ultrahigh frame rate — hampering the widespread utilities of such technology. Here, we propose a pixel super-resolution (pixel-SR) technique tailored for time-stretch imaging that preserves pixel resolution at a relaxed sampling rate. It harnesses the subpixel shifts between image frames inherently introduced by asynchronous digital sampling of the continuous time-stretch imaging process. Precise pixel registration is thus accomplished without any active opto-mechanical subpixel-shift control or other additional hardware. Here, we present the experimental pixel-SR image reconstruction pipeline that restores high-resolution time-stretch images of microparticles and biological cells (phytoplankton) at a relaxed sampling rate (≈2–5 GSa/s)—more than four times lower than the originally required readout rate (20 GSa/s) — is thus effective for high-throughput label-free, morphology-based cellular classification down to single-cell precision. Upon integration with the high-throughput image processing technology, this pixel-SR time-stretch imaging technique represents a cost-effective and practical solution for large scale cell-based phenotypic screening in biomedical diagnosis and machine vision for quality control in manufacturing. PMID:28303936

  14. A High-Resolution Time-to-Digital Converter Implemented in Field-Programmable-Gate-Arrays

    NASA Astrophysics Data System (ADS)

    Song, Jian; An, Qi; Liu, Shubin

    2006-02-01

    A high-resolution time-to-digital converter (TDC) implemented in a general purpose field-programmable-gate-array (FPGA) is presented. Dedicated carry lines of an FPGA are used as delay cells to perform time interpolation within the system clock period and to realize the fine time measurement. Two Gray-code counters, working on in-phase and out-of-phase system clocks respectively, are designed to get the stable value of the coarse time measurement. The fine time code and the coarse time counter value, along with the channel identifier, are then written into a first-in first-out (FIFO) buffer. Tests have been done to verify the performance of the TDC. The resolution after calibration can reach 50 ps

  15. Calculation of the time resolution of the J-PET tomograph using kernel density estimation

    NASA Astrophysics Data System (ADS)

    Raczyński, L.; Wiślicki, W.; Krzemień, W.; Kowalski, P.; Alfs, D.; Bednarski, T.; Białas, P.; Curceanu, C.; Czerwiński, E.; Dulski, K.; Gajos, A.; Głowacz, B.; Gorgol, M.; Hiesmayr, B.; Jasińska, B.; Kamińska, D.; Korcyl, G.; Kozik, T.; Krawczyk, N.; Kubicz, E.; Mohammed, M.; Pawlik-Niedźwiecka, M.; Niedźwiecki, S.; Pałka, M.; Rudy, Z.; Rundel, O.; Sharma, N. G.; Silarski, M.; Smyrski, J.; Strzelecki, A.; Wieczorek, A.; Zgardzińska, B.; Zieliński, M.; Moskal, P.

    2017-06-01

    In this paper we estimate the time resolution of the J-PET scanner built from plastic scintillators. We incorporate the method of signal processing using the Tikhonov regularization framework and the kernel density estimation method. We obtain simple, closed-form analytical formulae for time resolution. The proposed method is validated using signals registered by means of the single detection unit of the J-PET tomograph built from a 30 cm long plastic scintillator strip. It is shown that the experimental and theoretical results obtained for the J-PET scanner equipped with vacuum tube photomultipliers are consistent.

  16. 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.

  17. 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.

  18. 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

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

    DOE PAGES

    Tenboer, Jason; Basu, Shibom; Zatsepin, Nadia; ...

    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.

  20. Time-resolved High Spectral Resolution Observation of 2MASSW J0746425+200032AB

    NASA Astrophysics Data System (ADS)

    Wang, Ji; Prato, Lisa; Mawet, Dimitri

    2017-03-01

    Many brown dwarfs (BDs) exhibit photometric variability at levels from tenths to tens of percents. The photometric variability is related to magnetic activity or patchy cloud coverage, characteristic of BDs near the L–T transition. Time-resolved spectral monitoring of BDs provides diagnostics of cloud distribution and condensate properties. However, current time-resolved spectral studies of BDs are limited to low spectral resolution (R ∼ 100) with the exception of the study of Luhman 16 AB at a resolution of 100,000 using the VLT+CRIRES. This work yielded the first map of BD surface inhomogeneity, highlighting the importance and unique contribution of high spectral resolution observations. Here, we report on the time-resolved high spectral resolution observations of a nearby BD binary, 2MASSW J0746425+200032AB. We find no coherent spectral variability that is modulated with rotation. Based on simulations, we conclude that the coverage of a single spot on 2MASSW J0746425+200032AB is smaller than 1% or 6.25% if spot contrast is 50% or 80% of its surrounding flux, respectively. Future high spectral resolution observations aided by adaptive optics systems can put tighter constraints on the spectral variability of 2MASSW J0746425+200032AB and other nearby BDs.

  1. Simulations of the temporal and spatial resolution for a compact time-resolved electron diffractometer

    NASA Astrophysics Data System (ADS)

    Robinson, Matthew S.; Lane, Paul D.; Wann, Derek A.

    2016-02-01

    A novel compact electron gun for use in time-resolved gas electron diffraction experiments has recently been designed and commissioned. In this paper we present and discuss the extensive simulations that were performed to underpin the design in terms of the spatial and temporal qualities of the pulsed electron beam created by the ionisation of a gold photocathode using a femtosecond laser. The response of the electron pulses to a solenoid lens used to focus the electron beam has also been studied. The simulated results show that focussing the electron beam affects the overall spatial and temporal resolution of the experiment in a variety of ways, and that factors that improve the resolution of one parameter can often have a negative effect on the other. A balance must, therefore, be achieved between spatial and temporal resolution. The optimal experimental time resolution for the apparatus is predicted to be 416 fs for studies of gas-phase species, while the predicted spatial resolution of better than 2 nm-1 compares well with traditional time-averaged electron diffraction set-ups.

  2. 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

  3. Estimation of time resolution for DOI-PET detector using diameter 0.2 mm WLS fibers

    SciTech Connect

    Kobayashi, A.; Ito, H.; Han, S.; Kaneko, N.; Kawai, H.; Kodama, S.; Han, S.; Kamada, K.; Shoji, Y.; Yoshikawa, A.

    2015-07-01

    We are developing the whole-body PET detector with high position resolution (1 mm) and low cost (1 M dollars). Scintillator plates, Wave Length Sifting Fibers and SiPMs are used. In this work, time resolution of our PET detector is estimated. Our detector may also have good time resolution such as a few ps. (authors)

  4. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    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.

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

    PubMed

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

    2016-03-17

    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.

  7. Development of high time resolution measurement system of frequency characteristics in bioelectrical impedance for biodynamic analysis

    NASA Astrophysics Data System (ADS)

    Nakamura, Takao; Kusuhara, Toshimasa; Yamamoto, Yoshitake

    2006-11-01

    We have proposed biodynamic analysis using bioelectrical impedance at 50 kHz, which is measured with synchronous rectification method. In order to analyze impedance parameters in biodynamics, the measurement of frequency characteristics in bioelectrical impedance with a high time resolution are required. Therefore we have developed a high time resolution measurement system for bioelectrical impedance with 10 frequency points and time resolution of 1 ms. A voltage E A, which consisted of fundamental wave and 9 kinds of harmonic wave from 1 kHz to 1MHz, were converted to current. The current flowed through human body and a potential voltage, EV was detected in the measured part. After A/D conversion of EV and E A in the sampling frequency 2 MHz, data number 2048 points, the impedance were calculated using Fast Fourier Transform. The measured time 1.024 ms was the period of the fundamental wave and time resolution of this system. The specification is enough accuracy for measurement of bioelectrical impedance for biodynamic analysis.

  8. 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

  9. A 2.9 ps equivalent resolution interpolating time counter based on multiple independent coding lines

    NASA Astrophysics Data System (ADS)

    Szplet, R.; Jachna, Z.; Kwiatkowski, P.; Rozyc, K.

    2013-03-01

    We present the design, operation and test results of a time counter that has an equivalent resolution of 2.9 ps, a measurement uncertainty at the level of 6 ps, and a measurement range of 10 s. The time counter has been implemented in a general-purpose reprogrammable device Spartan-6 (Xilinx). To obtain both high precision and wide measurement range the counting of periods of a reference clock is combined with a two-stage interpolation within a single period of the clock signal. The interpolation involves a four-phase clock in the first interpolation stage (FIS) and an equivalent coding line (ECL) in the second interpolation stage (SIS). The ECL is created as a compound of independent discrete time coding lines (TCL). The number of TCLs used to create the virtual ECL has an effect on its resolution. We tested ECLs made from up to 16 TCLs, but the idea may be extended to a larger number of lines. In the presented time counter the coarse resolution of the counting method equal to 2 ns (period of the 500 MHz reference clock) is firstly improved fourfold in the FIS and next even more than 400 times in the SIS. The proposed solution allows us to overcome the technological limitation in achievable resolution and improve the precision of conversion of integrated interpolators based on tapped delay lines.

  10. Improvement of time resolution in large area single gap Resistive Plate Chambers

    NASA Astrophysics Data System (ADS)

    Bhatt, A. D.; Majumder, G.; Mondal, N. K.; Pathaleswar; Satyanarayana, B.

    2017-02-01

    The intrinsic gain of a single gap Resistive Plate Chamber (RPC) is affected by several factors, e.g., variation in the thicknesses of glass electrode, button and side spacer, different composition of gas due to improper flow, leaks in the detector volume, etc. The position dependent gain is one of the dominant components of the time resolution of a large area single gap RPC. Besides, strip multiplicity as well as lateral position of the trajectory of the charged particle in RPC strip also result in variation of timing information. The observation of large signals produced by the charged particles passing close to the button spacers also has some repercussion on the overall timing resolution of an RPC. A new offline correction technique to achieve time resolution below 1 ns is reported in this paper. This technique is validated using an RPC cosmic ray telescope (1 × 1m2) at TIFR. We also suggest a few alternative solutions to improve the time resolution during the operational phase of the INO-ICAL experiment. The techniques presented here are useful not only for ICAL, but also for any detector deploying RPCs in large scale.

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

    PubMed Central

    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.

    2013-01-01

    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. PMID:23750177

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Limitation of Time-of-Flight Resolution in the Ultra High Mass Range

    PubMed Central

    Lee, Jeonghoon

    2011-01-01

    In this work, we have examined the reason for the deterioration of resolution and mass accuracy of time-of-flight mass analyzers with increasing mass after the expansion induced kinetic energy has been eliminated by collisional cooling in an ion guide. Theoretically, removing the expansion–induced kinetic energy by collisional cooling permits the ions to travel along the ion guide axes without significant deviation so that they can be injected into the analyzer in a well-collimated ion beam with well-defined kinetic energy. If the ions can be injected into an orthogonal acceleration time-of-flight mass analyzer (oa-TOF) in this manner, high resolution mass analysis can be obtained regardless of mass or m/z. Unfortunately, high resolution did not result. It is our contention that the effusive expansion out of the first ion guide yields dispersive axial ejection that reduces TOF resolving power with increasing mass not m/z. PMID:21728303

  14. Fiber-coupled high-speed asynchronous optical sampling with sub-50 fs time resolution.

    PubMed

    Krauss, N; Nast, A; Heinecke, D C; Kölbl, C; Barros, H G; Dekorsy, T

    2015-02-09

    We present a fiber-coupled pump-probe system with a sub-50 fs time resolution and a nanosecond time window, based on high-speed asynchronous optical sampling. By use of a transmission grism pulse compressor, we achieve pump pulses with a pulse duration of 42 fs, an average power of 300 mW and a peak power exceeding 5 kW at a pulse repetition rate of 1 GHz after 6 m of optical fiber. With this system we demonstrate thickness mapping of soft X-ray mirrors at a sub-nm thickness resolution on a cm(2) scan area. In addition, terahertz field generation with resolved spectral components of up to 3.5 THz at a GHz frequency resolution is demonstrated.

  15. Ultrahigh resolution ex vivo ocular imaging using ultrashort acquisition time en face optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Grieve, Kate; Moneron, Gael; Dubois, Arnaud; LeGargasson, Jean-François; Boccara, Claude

    2005-08-01

    We explore the potential and the limitations of a new ultrashort acquisition time en face optical coherence tomography (OCT) technique in application to ocular imaging. The instrument is based on the Linnik interferometer, illuminated with a xenon flash lamp. Transverse resolution is determined by the numerical aperture of the microscope objectives, whilst axial resolution is governed by the source coherence length. An isotropic resolution of ~1 µm is achieved. The acquisition speed is determined by the flash pulse duration, i.e. 10 µs. A full two-dimensional en face tomographic image is captured in this time period. Preliminary results of imaging in ex vivo ocular tissues of the rat are presented and compared with results obtained using our original full-field OCT system. The possibility of extension to in vivo imaging is discussed. Part of the II EOS Topical Meeting on Physiological Optics (Granada, Spain, September 2004).

  16. Tablet disintegration studied by high-resolution real-time magnetic resonance imaging.

    PubMed

    Quodbach, Julian; Moussavi, Amir; Tammer, Roland; Frahm, Jens; Kleinebudde, Peter

    2014-01-01

    The present work employs recent advances in high-resolution real-time magnetic resonance imaging (MRI) to investigate the disintegration process of tablets containing disintegrants. A temporal resolution of 75 ms and a spatial resolution of 80 × 80 µm with a section thickness of only 600 µm were achieved. The histograms of MRI videos were quantitatively analyzed with MATLAB. The mechanisms of action of six commercially available disintegrants, the influence of relative tablet density, and the impact of disintegrant concentration were examined. Crospovidone seems to be the only disintegrant acting by a shape memory effect, whereas the others mainly swell. A higher relative density of tablets containing croscarmellose sodium leads to a more even distribution of water within the tablet matrix but hardly impacts the disintegration kinetics. Increasing the polacrilin potassium disintegrant concentration leads to a quicker and more thorough disintegration process. Real-time MRI emerges as valuable tool to visualize and investigate the process of tablet disintegration.

  17. 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.

  18. Super-resolution endoscopy for real-time wide-field imaging.

    PubMed

    Wang, Feifei; Lai, Hok Sum Sam; Liu, Lianqing; Li, Pan; Yu, Haibo; Liu, Zhu; Wang, Yuechao; Li, Wen Jung

    2015-06-29

    Resolving subcellular structures in vitro beyond optical diffraction barrier by a light microscope has achieved significant development since the advancement of super-resolution fluorescence microscopes, such as stimulated emission depletion (STED) microscopy, stochastic optical reconstruction microscopy (STORM) and photoactivated localization microscopy (PALM). However, the resolution of observation in deep and dense in vivo tissues is still confined to cellular level presently, and hence, exploring image details at subcellular level or even beyond organelle level in vivo has continued to attract much research attention. Currently, endoscopy provides an effective way to achieve in vivo observations and is compatible with mature optical microscopy technologies, but its resolution is usually confined to ~1 µm. Here we report a new endoscopy method by functionalizing graded-index (GRIN) lens with microspheres for real-time white-light or fluorescent super-resolution imaging. The capability of resolving objects with feature size of ~λ/5, which breaks the diffraction barrier of traditional GRIN lens based endoscopes by a factor of two, has been demonstrated by using this super-resolution endoscopy method. Further development of such a super-resolution endoscopy technique may provide new opportunities for in vivo life sciences studies.

  19. Annexin A1 promotes timely resolution of inflammation in murine gout.

    PubMed

    Galvão, Izabela; Vago, Juliana P; Barroso, Livia C; Tavares, Luciana P; Queiroz-Junior, Celso M; Costa, Vivian V; Carneiro, Fernanda S; Ferreira, Tatiana P; Silva, Patricia M R; Amaral, Flávio A; Sousa, Lirlândia P; Teixeira, Mauro M

    2017-03-01

    Gout is a self-limited inflammatory disease caused by deposition of monosodium urate (MSU) crystals in the joints. Resolution of inflammation is an active process leading to restoration of tissue homeostasis. Here, we studied the role of Annexin A1 (AnxA1), a glucocorticoid-regulated protein that has anti-inflammatory and proresolving actions, in resolution of acute gouty inflammation. Injection of MSU crystals in the knee joint of mice induced inflammation that was associated with expression of AnxA1 during the resolving phase of inflammation. Neutralization of AnxA1 with antiserum or blockade of its receptor with BOC-1 (nonselective) or WRW4 (selective) prevented the spontaneous resolution of gout. There was greater neutrophil infiltration after challenge with MSU crystals in AnxA1 knockout mice (AnxA1(-/-) ) and delayed resolution associated to decreased neutrophil apoptosis and efferocytosis. Pretreatment of mice with AnxA1-active N-terminal peptide (Ac2-26 ) decreased neutrophil influx, IL-1β, and CXCL1 production in periarticular joint. Posttreatment with Ac2-26 decreased neutrophil accumulation, IL-1β, and hypernociception, and improved the articular histopathological score. Importantly, the therapeutic effects of Ac2-26 were associated with increased neutrophils apoptosis and shortened resolution intervals. In conclusion, AnxA1 plays a crucial role in the context of acute gouty inflammation by promoting timely resolution of inflammation.

  20. 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

  1. 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.

  2. Measurement of the RMS Parity Violating Matrix Element in URANIUM-239

    NASA Astrophysics Data System (ADS)

    Zhu, Xianzhou (Joe).

    We report the first determination of the Root -Mean-Square (RMS) parity violating matrix element in a compound nucleus (CN) system, ^{239 }U. The experiment was performed using the intense pulsed epithermal neutron beam available at the Los Alamos Neutron Scattering Center (LANSCE). The helicity dependence of neutron transmission through a spin zero target (^{238}U) is measured for neutron energies from 6 eV to 300 eV. Parity violation is analyzed on 17 p-wave resonances among which five show 2sigma or larger effects. The largest is a 7sigma effect at the 63.5 eV resonance which shows a parity violating asymmetry of p = 2.6%. A likelihood analysis is performed on these 17 parity violating asymmetries, and the RMS parity violating matrix element is determined for the first time to be M = 0.59_sp{-0.25}{+0.50} meV which corresponds to a parity violating spreading width ofGamma^{PV} = (1.0 {+1.7atop -0.8} ) times 10^{-7} {rm eV}.Using statistical nuclear spectroscopy, we are able to relate M to the effective nucleon-nucleon (NN) interaction. The result is | alpha_{p}| ~ (4 {+4atop -2} ) times 10^{-7} where alpha_{p} is the ratio of the parity violating strength to the parity conserving strength in the effective NN interaction. This agrees qualitatively with the estimate of free NN interaction. The consistency of the experimental measurement with expectation suggests that the manifestation of parity violating NN interaction in CN is understood. It is a challenging problem for the theorists to relate the RMS matrix element in the CN to the underlying NN interaction, therefore providing alternative ways to determine the Desplanques -Donoghue-Holstein (DDH) parameters of the NN interaction. The success of the parity violation study also validates the proposed experiment of studying the time reversal symmetry violation utilizing the large enhancement in the CN.

  3. 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.

  4. Monte Carlo study of the time resolution of scintillating fibre detectors

    NASA Astrophysics Data System (ADS)

    Ziembicki, M.; Marzec, J.; Dziewiecki, M.

    2007-08-01

    This paper presents the results of a Monte Carlo study of the time resolution of a scintillating fibre detector and analyses its dependence on the various aspects of detector construction. The estimations of the theoretical time resolutions for detectors with different numbers of fibre layers and different types of acrylic-based fibre coatings are presented. The method is suggested to decrease the rate counting effects encountered in high rate applications. It has been observed that for dual cladding fibres with a fluorinated polymer used for the outer cladding, the most significant factor contributing to the time resolution is the number of fibre layers, with the fibre coating being the marginal one. Another observation shows that the introduction of a gap between the fibre and the photomultiplier glass window allows the reduction of the number of photoelectrons by 25% with only a slight decrease in the time resolution, which may be helpful in decreasing the pulse pile-up effects and the photomultiplier gain, commonly observed under high rate conditions.

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

    DOE PAGES

    Atanov, N.; Baranov, V.; Colao, F.; ...

    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.

  6. Picosecond resolution on relativistic heavy ions' time-of-flight measurement

    NASA Astrophysics Data System (ADS)

    Ebran, A.; Taieb, J.; Belier, G.; Chatillon, A.; Laurent, B.; Martin, J.-F.; Pellereau, E.

    2013-11-01

    We developed a time-of-flight measurement system for relativistic heavy ions with a requested resolution of 40 ps Full Width Half Maximum. Such a resolution is mandatory to assign the correct mass number to every fission fragment, identified using the Bρ-ToF-ΔE method with the recoil spectrometer designed for the SOFIA experiment-which hold very recently at GSI. To achieve such a performance, fast plastic scintillators read-out by dedicated photomultiplier tubes were chosen among other possible options. We have led several test-measurements from 2009 to 2011, in order to investigate: the effect of the addition of a quenching molecule in the scintillator's matrix, the influence of the detector's size and the impact of the photomultiplier tube. The contribution of the dedicated electronics is also characterized. Time-of-flight measurements were performed realized with electron pulses and relativistic heavy ions, respectively provided by the LASER driven electron-accelerator (ELSA) at CEA-DAM Ile-de-France and by the SIS18/FRS facility at GSI. The reported results exhibit a time resolution better than 20 ps Full Width Half Maximum reached with the last prototype at GSI with an Uranium beam. These results confirm that the SOFIA experiment should enable the measurement of the relativistic fission fragments' time-of-flight with the requested resolution.

  7. 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

  8. Methods of real time high resolution phase detection for use in laser rangefinders

    NASA Astrophysics Data System (ADS)

    Budzyn, Grzegorz; Tkaczyk, Jakub; Podzorny, Tomasz; Rzepka, Janusz

    2014-05-01

    The purpose of this paper is the comparison of two phase measurement methods commonly used in precision rangefinder systems and their suitability to work with high frequency signals. Basic detection circuits for an FFT and an IQ-based methods were proposed and hardware limitations were considered. A set of simulations to assess the behavior of the algorithms in the presence of the noise was performed. An influence of the ADC resolution on the measurement accuracy was also assessed. It is proved that the IQ-based method shows better resilience to signal distortions and puts lower requirements on the ADC circuit thus is better suited for real time high resolution laser rangefinders.

  9. 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.

  10. Broadband ultraviolet-visible transient absorption spectroscopy in the nanosecond to microsecond time domain with sub-nanosecond time resolution.

    PubMed

    Lang, Bernhard; Mosquera-Vázquez, Sandra; Lovy, Dominique; Sherin, Peter; Markovic, Vesna; Vauthey, Eric

    2013-07-01

    A combination of sub-nanosecond photoexcitation and femtosecond supercontinuum probing is used to extend femtosecond transient absorption spectroscopy into the nanosecond to microsecond time domain. Employing a passively Q-switched frequency tripled Nd:YAG laser and determining the jitter of the time delay between excitation and probe pulses with a high resolution time delay counter on a single-shot basis leads to a time resolution of 350 ps in picosecond excitation mode. The time overlap of almost an order of magnitude between fs and sub-ns excitation mode permits to extend ultrafast transient absorption (TA) experiments seamlessly into time ranges traditionally covered by laser flash photolysis. The broadband detection scheme eases the identification of intermediate reaction products which may remain undetected in single-wavelength detection flash photolysis arrangements. Single-shot referencing of the supercontinuum probe with two identical spectrometer/CCD arrangements yields an excellent signal-to-noise ratio for the so far investigated chromophores in short to moderate accumulation times.

  11. Attosecond-resolution timing jitter characterization of free-running mode-locked lasers.

    PubMed

    Kim, Jungwon; Chen, Jeff; Cox, Jonathan; Kärtner, Franz X

    2007-12-15

    Timing jitter characterization of optical pulse trains from free-running mode-locked lasers with attosecond resolution is demonstrated using balanced optical cross correlation in the timing detector and the timing delay configurations. In the timing detector configuration, the balanced cross correlation between two mode-locked lasers synchronized by a low-bandwidth phase-locked loop is used to measure the timing jitter spectral density outside the locking bandwidth. In addition, the timing delay configuration using a 325 m long timing-stabilized fiber link enables the characterization of timing jitter faster than the delay time. The limitation set by shot noise in this configuration is 2.2 x 10(-8) fs(2)/Hz corresponding to 470 as in 10 MHz bandwidth.

  12. Enhancing the resolution of non-stationary seismic data using improved time-frequency spectral modelling

    NASA Astrophysics Data System (ADS)

    Zhou, Huai-lai; Wang, Chang-cheng; Marfurt, Kurt J.; Jiang, Yi-wei; Bi, Jian-xia

    2016-04-01

    Maximizing vertical resolution is a key objective in seismic data processing. Early deconvolution and spectral balancing algorithms assumed that the seismic source wavelet was temporally invariant, or stationary. In practice, seismic scattering and attenuation give rise to non-stationary seismic source wavelets. To address this issue, most conventional time-varying deconvolution wavelet shaping and spectral modelling techniques using the stationary polynomial fitting assume the wavelet to be locally stationary within a small number of overlapping analysis windows while the fitting coefficients are invariant with all the frequencies. In this paper, we show an improvement obtained by modelling smoothly varying spectra of the seismic wavelet using non-stationary polynomial fitting in the time-frequency domain. We first decompose each seismic trace using a generalized S-transform that provides a good time-frequency distribution for the estimation of the time-varying wavelet spectra. We then model the slowly varying source wavelet spectrum at each time sample by a smooth low-order polynomial. Finally, we spectrally balance the modelled wavelet to flatten the seismic response, thereby increasing vertical resolution. We calibrate the algorithm on a simple synthetic and then apply it to a 3-D land survey acquired in western China, showing the value on both vertical slices through seismic amplitude and attribute time slices. Our new algorithm significantly improves the vertical resolution of the seismic signal, while not increasing the noise.

  13. Super-resolution infrared time measurement method based on target dynamic characteristics

    NASA Astrophysics Data System (ADS)

    Li, Bin; Hu, Qiuping; Tang, Zili; Zhang, Sanxi; Zhang, Hua; Yue, Peng; Liu, Biao

    2016-10-01

    High precision time control in the use of weapons and equipment is an important part of product design and development. In order to satisfy the data acquisition requirement of high accuracy and reliability in the rapid flight process, the super-resolution time measurement method based on target dynamic characteristics was put forward and proved by the cabin opening time measurement experiment. First, the changes of explosion pressure wave and image in the cabin opening process were analyzed in detail. The change regulation of explosion flame shape was analyzed by the characteristics of typical pressure wave, and then the high frequency images of the explosion process were shot by high speed camera. The change regulation of the infrared image was obtained through the comparison of visible and infrared image mechanism. Then, combined with the target motion features, and the observed station parameters, the observation model of movement process was built. On the basis of the above research, the infrared characteristic and the movement characteristic were transformed, and the super resolution model was established. For test method, combined with the actual class time measuring process in experimental design, to obtain the special radar for measuring high precision open class time as the true value of the precision appraisal. Experimental results show that the infrared feature and motion feature can realize open class time super resolution measurement, can effectively improve the accuracy and reliability of the data, to achieve specific action of high accuracy measurement that plays an important role by making use of the target dynamic characteristics.

  14. Using high time resolution aerosol and number size distribution measurements to estimate atmospheric extinction.

    PubMed

    Malm, William C; McMeeking, Gavin R; Kreidenweis, Sonia M; Levin, Ezra; Carrico, Christian M; Day, Derek E; Collett, Jeffrey L; Lee, Taehyoung; Sullivan, Amy P; Raja, Suresh

    2009-09-01

    Rocky Mountain National Park is experiencing reduced visibility and changes in ecosystem function due to increasing levels of oxidized and reduced nitrogen. The Rocky Mountain Atmospheric Nitrogen and Sulfur (RoMANS) study was initiated to better understand the origins of sulfur and nitrogen species as well as the complex chemistry occurring during transport from source to receptor. As part of the study, a monitoring program was initiated for two 1-month time periods--one during the spring and the other during late summer/fall. The monitoring program included intensive high time resolution concentration measurements of aerosol number size distribution, inorganic anions, and cations, and 24-hr time resolution of PM2.5 and PM10 mass, sulfate, nitrate, carbon, and soil-related elements concentrations. These data are combined to estimate high time resolution concentrations of PM2.5 and PM10 aerosol mass and fine mass species estimates of ammoniated sulfate, nitrate, and organic and elemental carbon. Hour-by-hour extinction budgets are calculated by using these species concentration estimates and measurements of size distribution and assuming internal and external particle mixtures. Summer extinction was on average about 3 times higher than spring extinction. During spring months, sulfates, nitrates, carbon mass, and PM10 - PM2.5 mass contributed approximately equal amounts of extinction, whereas during the summer months, carbonaceous material extinction was 2-3 times higher than other species.

  15. Flare stars and solar bursts - High resolution in time and frequency

    NASA Technical Reports Server (NTRS)

    Lang, K. R.

    1986-01-01

    Coronal loops on the sun and nearby stars are studied using observations at 20-cm wavelength with high resolution in time and frequency. Observations of the dwarf M star AD Leonis with high time resolution led to the discovery of a quasi-periodic train of circularly polarized spikes with a mean periodicity of 32 + or - 5 ms and a total duration of 150 ms. Observations at closely spaced wavelengths using the VLA revealed a narrow-band structure in solar bursts and in the slowly varying radiation of the dwarf M star YZ Canis Minoris. This narrow-band emission may be attributed to electron-cyclotron maser radiation. Maser action at the second or first harmonic of the gyrofrequency implies magnetic field strengths of 250 and 500 G, respectively. Hence, observations with high resolution in time and frequency suggest coherent processs in the coronas of the sun and dwarf M stars. It is noted that the scientific potential suggested by the present data can be realized by the development of a solar-stellar synthesis radiotelescope. This instrument would be dedicated to solar and stellar observations with high angular, temporal, and frequency resolution.

  16. Daily High-Resolution Flood Maps of Africa: 1992-present with Near Real Time Updates

    NASA Astrophysics Data System (ADS)

    Picton, J.; Galantowicz, J. F.; Root, B.

    2016-12-01

    The ability to characterize past and current flood extents frequently, accurately, and at high resolution is needed for many applications including risk assessment, wetlands monitoring, and emergency management. However, remote sensing methods have not been capable of meeting all of these requirements simultaneously. Cloud cover too often obscures the surface for visual and infrared sensors and observations from radar sensors are too infrequent to create consistent historical databases or monitor evolving events. Lower-resolution (10-50 km) passive microwave sensors, such as SSM/I, AMSR-E, and AMSR2, are sensitive to water cover, acquire useful data during clear and cloudy conditions, have revisit periods of up to twice daily, and provide a continuous record of data from 1992 to the present. What they lack most is the resolution needed to map flood extent. We will present results from a flood mapping system capable of producing high-resolution (90-m) flood extent depictions from lower resolution microwave data. The system uses the strong sensitivity of microwave data to surface water coverage combined with land surface and atmospheric data to derive daily flooded fraction estimates on a sensor-footprint basis. The system downscales flooded fraction to make high-resolution Boolean flood extent depictions that are spatially continuous and consistent with the lower resolution data. The downscaling step is based on a relative floodability (RF) index derived from higher-resolution topographic and hydrological data. We process RF to create a flooded fraction threshold map that relates each 90-m grid point to the surrounding terrain at the microwave scale. We have derived daily, 90-m resolution flood maps for Africa covering 1992-present using SSM/I, AMSR-E, and AMSR2 data and we are now producing new daily maps in near real time. The flood maps are being used by the African Risk Capacity (ARC) Agency to underpin an intergovernmental river flood insurance program in

  17. Minisuperspace model of Machian resolution of Problem of Time. I. Isotropic case

    NASA Astrophysics Data System (ADS)

    Anderson, Edward

    2014-05-01

    A local resolution to the Problem of Time that is Machian and was previously demonstrated for relational mechanics models is here shown to work for a more widely studied quantum cosmological model. I.e., closed isotropic minisuperspace GR with minimally coupled scalar field matter. This resolution uses work firstly along the lines of Barbour's at the classical level. Secondly, it uses a Machianized version of the semiclassical approach to quantum cosmology (the resolution given is not more than semiclassical). Finally, it uses a Machianized version of a combined semiclassical histories timeless records scheme along the lines of Halliwell's work. This program's goal is the treatment of inhomogeneous perturbations about the present paper's model. This draws both from this paper's minisuperspace work and from qualitative parallels with relational particle mechanics, since both have nontrivial notions of inhomogeneity/structure (clumping) as well as nontrivial linear constraints.

  18. Spatial resolution analysis for time-domain diffuse optical tomography based on a perturbation model

    NASA Astrophysics Data System (ADS)

    Konovalov, Alexander B.; Vlasov, Vitaly V.

    2014-01-01

    We estimate a limit to spatial resolution in time-domain diffuse optical tomography (DOT) based on a perturbation model by Lyubimov. In the context of structure reconstruction accuracy we consider and compare three approaches to the inverse DOT problem. The first reconstructs diffuse tomograms from straight lines; the second does it from curvilinear average trajectories of photons; and the third uses the total banana-like distributions of photon trajectories. For getting estimates to resolution, we derive analytical expressions for the point spread function and the modulation transfer function, and perform a numerical experiment to reconstruct rectangular scattering objects with circular absorbing inhomogeneities. It is shown that reconstruction with photon trajectory distributions instead of straight lines gives a gain of about order of magnitude in resolution and attains the accuracy of multistep nonlinear DOT algorithms.

  19. 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.

  20. 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

    2016-03-07

    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.

  1. Detection efficiency, spatial and timing resolution of thermal and cold neutron counting MCP detectors

    NASA Astrophysics Data System (ADS)

    Tremsin, A. S.; McPhate, J. B.; Vallerga, J. V.; Siegmund, O. H. W.; Hull, J. S.; Feller, W. B.; Lehmann, E.

    2009-06-01

    Neutron counting detectors with boron or gadolinium doped microchannel plates (MCPs) have very high detection efficiency, spatial and temporal resolution, and have a very low readout noise. In this paper we present the results of both theoretical predictions and experimental evaluations of detection efficiency and spatial resolution measured at cold and thermal neutron beamlines. The quantum detection efficiency of a detector (not fully optimized) was measured to be 43% and 16% for the cold and thermal beamlines, respectively. The experiments also demonstrate that the spatial resolution can be better than 15 μm—highest achievable with the particular MCP pore dimension used in the experiment, although more electronics development is required in order to increase the counting rate capabilities of those <15 μm resolution devices. The timing accuracy of neutron detection is on the scale of few μs and is limited by the neutron absorption depth in the detector. The good agreement between the predicted and measured performance allows the optimization of the detector parameters in order to achieve the highest spatial resolution and detection efficiency in future devices.

  2. 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.

  3. High-resolution time-resolved extreme ultraviolet spectroscopy on NSTX.

    PubMed

    Lepson, J K; Beiersdorfer, P; Clementson, J; Bitter, M; Hill, K W; Kaita, R; Skinner, C H; Roquemore, A L; Zimmer, G

    2012-10-01

    We report on upgrades to the flat-field grazing-incidence grating spectrometers X-ray and Extreme Ultraviolet Spectrometer (XEUS) and Long-Wavelength Extreme Ultraviolet Spectrometer (LoWEUS), at the National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Laboratory. XEUS employs a variable space grating with an average spacing of 2400 lines/mm and covers the 9-64 Å wavelength band, while LoWEUS has an average spacing of 1200 lines/mm and is positioned to monitor the 90-270 Å wavelength band. Both spectrometers have been upgraded with new cameras that achieve 12.5 ms time resolution. We demonstrate the new time resolution capability by showing the time evolution of iron in the NSTX plasma.

  4. 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

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

    PubMed

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

    2015-06-01

    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.

  6. Rapid Diagnosis of Tuberculosis by Real-Time High-Resolution Imaging of Mycobacterium tuberculosis Colonies.

    PubMed

    Ghodbane, Ramzi; Asmar, Shady; Betzner, Marlena; Linet, Marie; Pierquin, Joseph; Raoult, Didier; Drancourt, Michel

    2015-08-01

    Culture remains the cornerstone of diagnosis for pulmonary tuberculosis, but the fastidiousness of Mycobacterium tuberculosis may delay culture-based diagnosis for weeks. We evaluated the performance of real-time high-resolution imaging for the rapid detection of M. tuberculosis colonies growing on a solid medium. A total of 50 clinical specimens, including 42 sputum specimens, 4 stool specimens, 2 bronchoalveolar lavage fluid specimens, and 2 bronchial aspirate fluid specimens were prospectively inoculated into (i) a commercially available Middlebrook broth and evaluated for mycobacterial growth indirectly detected by measuring oxygen consumption (standard protocol) and (ii) a home-made solid medium incubated in an incubator featuring real-time high-resolution imaging of colonies (real-time protocol). Isolates were identified by Ziehl-Neelsen staining and matrix-assisted laser desorption ionization-time of flight mass spectrometry. Use of the standard protocol yielded 14/50 (28%) M. tuberculosis isolates, which is not significantly different from the 13/50 (26%) M. tuberculosis isolates found using the real-time protocol (P = 1.00 by Fisher's exact test), and the contamination rate of 1/50 (2%) was not significantly different from the contamination rate of 2/50 (4%) using the real-time protocol (P = 1.00). The real-time imaging protocol showed a 4.4-fold reduction in time to detection, 82 ± 54 h versus 360 ± 142 h (P < 0.05). These preliminary data give the proof of concept that real-time high-resolution imaging of M. tuberculosis colonies is a new technology that shortens the time to growth detection and the laboratory diagnosis of pulmonary tuberculosis.

  7. Review: Rusticle Formation on the RMS Titanic and the Potential Influence of Oceanography

    NASA Astrophysics Data System (ADS)

    Salazar, Maxsimo; Little, Brenda

    2017-04-01

    Meter length iron-rich rusticles on the RMS Titanic contain bacteria that reportedly mobilize iron from the ship structure at a rate that will reduce the wreck to rust in decades. Other sunken ships, such as the World War II shipwrecks in the Gulf of Mexico (GOM) are also similarly covered. However, at the GOM sites, rusticles are only centimeters in length. Minimal differences in water temperature (a few °C) between the two sites and comparable exposure times from wreckage to discovery cannot rationalize the extreme differences in rusticle length. One possible explanation for the observed difference in rusticle size is the differing amounts of dissolved or colloidal iron at the two locations.

  8. Review: Rusticle Formation on the RMS Titanic and the Potential Influence of Oceanography

    NASA Astrophysics Data System (ADS)

    Salazar, Maxsimo; Little, Brenda

    2017-01-01

    Meter length iron-rich rusticles on the RMS Titanic contain bacteria that reportedly mobilize iron from the ship structure at a rate that will reduce the wreck to rust in decades. Other sunken ships, such as the World War II shipwrecks in the Gulf of Mexico (GOM) are also similarly covered. However, at the GOM sites, rusticles are only centimeters in length. Minimal differences in water temperature (a few °C) between the two sites and comparable exposure times from wreckage to discovery cannot rationalize the extreme differences in rusticle length. One possible explanation for the observed difference in rusticle size is the differing amounts of dissolved or colloidal iron at the two locations.

  9. Near-real-time mosaics from high-resolution side-scan sonar

    USGS Publications Warehouse

    Danforth, William W.; O'Brien, Thomas F.; Schwab, W.C.

    1991-01-01

    High-resolution side-scan sonar has proven to be a very effective tool for stuyding and understanding the surficial geology of the seafloor. Since the mid-1970s, the US Geological Survey has used high-resolution side-scan sonar systems for mapping various areas of the continental shelf. However, two problems typically encountered included the short range and the high sampling rate of high-resolution side-scan sonar systems and the acquisition and real-time processing of the enormous volume of sonar data generated by high-resolution suystems. These problems were addressed and overcome in August 1989 when the USGS conducted a side-scan sonar and bottom sampling survey of a 1000-sq-km section of the continental shelf in the Gulf of Farallones located offshore of San Francisco. The primary goal of this survey was to map an area of critical interest for studying continental shelf sediment dynamics. This survey provided an opportunity to test an image processing scheme that enabled production of a side-scan sonar hard-copy mosaic during the cruise in near real-time.

  10. STS-39 SPAS-II IBSS is grappled by remote manipulator system (RMS)

    NASA Image and Video Library

    1991-05-06

    STS039-19-015 (28 April- 6 May 1991) --- This STS-39 35mm scene shows the Strategic Defense Initiative Organization (SDIO) Shuttle Pallet Satellite (SPAS-II) on the end of the remote manipulator system (RMS) end effector. During the eight-day flight, SPAS collected data in both a free-flying mode and while attached to the RMS.

  11. Improving Critical Thinking Skills of College Students through RMS Model for Learning Basic Concepts in Science

    ERIC Educational Resources Information Center

    Muhlisin, Ahmad; Susilo, Herawati; Amin, Mohamad; Rohman, Fatchur

    2016-01-01

    The purposes of this study were to: 1) Examine the effect of RMS learning model towards critical thinking skills. 2) Examine the effect of different academic abilities against critical thinking skills. 3) Examine the effect of the interaction between RMS learning model and different academic abilities against critical thinking skills. The research…

  12. Improving Critical Thinking Skills of College Students through RMS Model for Learning Basic Concepts in Science

    ERIC Educational Resources Information Center

    Muhlisin, Ahmad; Susilo, Herawati; Amin, Mohamad; Rohman, Fatchur

    2016-01-01

    The purposes of this study were to: 1) Examine the effect of RMS learning model towards critical thinking skills. 2) Examine the effect of different academic abilities against critical thinking skills. 3) Examine the effect of the interaction between RMS learning model and different academic abilities against critical thinking skills. The research…

  13. Direct Push Optical Screening Tool for High-Resolution, Real-Time Mapping of Chlorinated Solvent DNAPL Architecture

    DTIC Science & Technology

    2016-04-01

    FINAL REPORT Direct Push Optical Screening Tool for High-Resolution, Real- Time Mapping of Chlorinated Solvent DNAPL Architecture ESTCP Project ER...Direct Push Optical Screening Tool for High Resolution, Real-time Mapping of Chlorinated Solvent DNAPL Architecture Murray Einarson Haley...for real-time, high-resolution mapping of petroleum hydrocarbon and coal tar-based NAPL source zones. The objective of this project is to demonstrate

  14. Direct Push Optical Screening Tool for High Resolution, Real-Time Mapping of Chlorinated Solvent DNAPL Architecture

    DTIC Science & Technology

    2016-07-01

    ER-201121) Direct Push Optical Screening Tool for High- Resolution, Real-Time Mapping of Chlorinated Solvent DNAPL Architecture July 2016 This...Report April 2011 - March 2016 Direct Push Optical Screening Tool for High Resolution, Real-time Mapping of Chlorinated Solvent DNAPL Architecture...tools are currently available for real-time, high-resolution mapping of petroleum hydrocarbon and coal tar-based NAPL source zones. The objective of

  15. High resolution time to digital converter for the KM3NeT neutrino telescope

    NASA Astrophysics Data System (ADS)

    Calvo, D.; Real, D.

    2015-01-01

    The KM3NeT collaboration aims at 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 photomultipliers of small photocathode area. The readout and data acquisition system of KM3NeT has to collect, treat and send to shore, the enormous amount of data produced by the photomultipliers. For this purpose, 31 high-resolution time-interval measuring channels based on time to digital converter are implemented on the field-programmable gate arrays. Architectures with low resources occupancy are desirable allowing the implementation of other instrumentation, communication and synchronization systems on the same device. The required resolution to measure both, time of flight and time-stamp must be 1 ns. A 4-Oversampling technique with two high frequency clocks and an asymmetric FIFO memory is used to achieve this resolution. The proposed firmware has been developed in Xilinx Kintex-7.

  16. 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.

  17. Trade-offs between structural integrity and acquisition time in stochastic super-resolution microscopy techniques

    NASA Astrophysics Data System (ADS)

    Rupprecht, Jean-François; Martinez-Marrades, Ariadna; Zhang, Zhen; Changede, Rishita; Kanchanawong, Pakorn; Tessier, Gilles

    2017-09-01

    Widefield stochastic microscopy techniques such as PALM or STORM rely on the progressive accumulation of a large number of frames, each containing a scarce number of super-resolved point images. We justify that the redundancy in the localization of detected events imposes a specific limit on the temporal resolution. Based on a theoretical model, we derive analytical predictions for the minimal time required to obtain a reliable image at a given spatial resolution, called image completion time. In contrast to standard assumptions, we find that the image completion time scales logarithmically with the ratio of the image size by the spatial resolution volume. We justify that this non-linear relation is the hallmark of a random coverage problem. We propose a method to estimate the risk that the image reconstruction is not complete, which we apply to an experimental data set. Our results provide a theoretical framework to quantify the pattern detection efficiency and to optimize the trade-off between image coverage and acquisition time, with applications to $1$, $2$ or $3$ dimension structural imaging.

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

    PubMed

    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.

  19. Large aperture fast neutron imaging detector with 10-ns time resolution

    NASA Astrophysics Data System (ADS)

    Arikawa, Y.; Matsubara, S.; Abe, Y.; Kato, Y.; Kishimoto, H.; Yogo, A.; Nishimura, H.; Nakai, M.; Shiraga, H.; Fujioka, S.; Azechi, H.; Otake, Y.; Mima, K.; Honda, Y.

    2017-02-01

    Fast neutrons, which are neutrons with energies greater than 1 MeV, are expected to be a source of nondestructive inspection for a large-size infrastructure such as a bridge girder because of their mean free path exceeding the meter. A neutron-imaging device with 10-ns time resolution can discriminate pulsed neutrons from X-rays via time of flight. For this purpose, we require a fast-response neutron imager with large aperture and high image resolution. A neutron-imaging device with time resolution of 10 ns and aperture size of 40 cm × 60 cm was developed. It was filled with fast response liquid scintillator [1] in an aluminum honeycomb plate, which converts neutrons to optical light images. The scintillation light images were relayed using an optical lens and detected using a fast response image intensified CCD. The detector was tested at an electron linear accelerator (LINAC) facility in Osaka University. A short X-ray pulse (30 ps pulse duration) was generated using LINAC, and X-ray radiograph images were obtained with a 10- ns exposure time duration. The radiograph images were well attenuated within 10-ns from the X-ray injection. A high energy X-ray image and a neutron radiograph image of a 30-cm thick concrete block with iron blocks located behind it were successfully observed. This promising technique could facilitate nondestructive inspection of large concrete constructions.

  20. 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.

  1. 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.

  2. A novel time-multiplexed autostereoscopic multiview full resolution 3D display

    NASA Astrophysics Data System (ADS)

    Liou, Jian-Chiun; Chen, Fu-Hao

    2012-03-01

    Many people believe that in the future, autostereoscopic 3D displays will become a mainstream display type. Achievement of higher quality 3D images requires both higher panel resolution and more viewing zones. Consequently, the transmission bandwidth of the 3D display systems involves enormous amounts of data transfer. We propose and experimentally demonstrate a novel time-multiplexed autostereoscopic multi-view full resolution 3D display based on the lenticular lens array in association with the control of the active dynamic LED backlight. The lenticular lenses of the lens array optical system receive the light and deflect the light into each viewing zone in a time sequence. The crosstalk under different observation scanning angles is showed, including the cases of 4-views field scanning. The crosstalk of any view zones is about 5% respectively; the results are better than other 3D type.

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

    SciTech Connect

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

    2016-11-15

    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.

  4. Relation of comorbidities and patient navigation with the time to diagnostic resolution after abnormal cancer screening.

    PubMed

    Whitley, Elizabeth M; Raich, Peter C; Dudley, Donald J; Freund, Karen M; Paskett, Electra D; Patierno, Steven R; Simon, Melissa; Warren-Mears, Victoria; Snyder, Frederick R

    2017-01-01

    Whether patient navigation improves outcomes for patients with comorbidities is unknown. The aims of this study were to determine the effect of comorbidities on the time to diagnostic resolution after an abnormal cancer screening test and to examine whether patient navigation improves the timeliness and likelihood of diagnostic resolution for patients with comorbidities in comparison with no navigation. A secondary analysis of comorbidity data collected by Patient Navigation Research Program sites using the Charlson Comorbidity Index (CCI) was conducted. The participants were 6,349 patients with abnormal breast, cervical, colon, or prostate cancer screening tests between 2007 and 2011. The intervention was patient navigation or usual care. The CCI data were highly skewed across projects and cancer sites, and the CCI scores were categorized as 0 (CCI score of 0 or no comorbidities identified; 76% of cases); 1 (CCI score of 1; 16% of cases), or 2 (CCI score ≥ 2; 8% of cases). Separate adjusted hazard ratios for each site and cancer type were obtained, and then they were pooled with a meta-analysis random effects methodology. Patients with a CCI score ≥ 2 had delayed diagnostic resolution after an abnormal cancer screening test in comparison with those with no comorbidities. Patient navigation reduced delays in diagnostic resolution, with the greatest benefits seen for those with a CCI score ≥ 2. Persons with a CCI score ≥ 2 experienced significant delays in timely diagnostic care in comparison with patients without comorbidities. Patient navigation was effective in reducing delays in diagnostic resolution among those with CCI scores > 1. Cancer 2017;123:312-318. © 2016 American Cancer Society. © 2016 American Cancer Society.

  5. Reference-free, high-resolution measurement method of timing jitter spectra of optical frequency combs

    PubMed Central

    Kwon, Dohyeon; Jeon, Chan-Gi; Shin, Junho; Heo, Myoung-Sun; Park, Sang Eon; Song, Youjian; Kim, Jungwon

    2017-01-01

    Timing jitter is one of the most important properties of femtosecond mode-locked lasers and optical frequency combs. Accurate measurement of timing jitter power spectral density (PSD) is a critical prerequisite for optimizing overall noise performance and further advancing comb applications both in the time and frequency domains. Commonly used jitter measurement methods require a reference mode-locked laser with timing jitter similar to or lower than that of the laser-under-test, which is a demanding requirement for many laser laboratories, and/or have limited measurement resolution. Here we show a high-resolution and reference-source-free measurement method of timing jitter spectra of optical frequency combs using an optical fibre delay line and optical carrier interference. The demonstrated method works well for both mode-locked oscillators and supercontinua, with 2 × 10−9 fs2/Hz (equivalent to −174 dBc/Hz at 10-GHz carrier frequency) measurement noise floor. The demonstrated method can serve as a simple and powerful characterization tool for timing jitter PSDs of various comb sources including mode-locked oscillators, supercontinua and recently emerging Kerr-frequency combs; the jitter measurement results enabled by our method will provide new insights for understanding and optimizing timing noise in such comb sources. PMID:28102352

  6. Reference-free, high-resolution measurement method of timing jitter spectra of optical frequency combs

    NASA Astrophysics Data System (ADS)

    Kwon, Dohyeon; Jeon, Chan-Gi; Shin, Junho; Heo, Myoung-Sun; Park, Sang Eon; Song, Youjian; Kim, Jungwon

    2017-01-01

    Timing jitter is one of the most important properties of femtosecond mode-locked lasers and optical frequency combs. Accurate measurement of timing jitter power spectral density (PSD) is a critical prerequisite for optimizing overall noise performance and further advancing comb applications both in the time and frequency domains. Commonly used jitter measurement methods require a reference mode-locked laser with timing jitter similar to or lower than that of the laser-under-test, which is a demanding requirement for many laser laboratories, and/or have limited measurement resolution. Here we show a high-resolution and reference-source-free measurement method of timing jitter spectra of optical frequency combs using an optical fibre delay line and optical carrier interference. The demonstrated method works well for both mode-locked oscillators and supercontinua, with 2 × 10‑9 fs2/Hz (equivalent to ‑174 dBc/Hz at 10-GHz carrier frequency) measurement noise floor. The demonstrated method can serve as a simple and powerful characterization tool for timing jitter PSDs of various comb sources including mode-locked oscillators, supercontinua and recently emerging Kerr-frequency combs; the jitter measurement results enabled by our method will provide new insights for understanding and optimizing timing noise in such comb sources.

  7. 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)

  8. A high resolution laser ranging system based on time-correlated single-photon counting technology

    NASA Astrophysics Data System (ADS)

    Yang, Yixin; Wang, Huanqin; Huang, Zhe; Cao, Yangyang; Gui, Huaqiao

    2014-12-01

    Laser ranging has become an important method for both distance measurements and acquisition of threedimensional (3D) images. In this paper, a laser ranging system based on Time-Correlated Single-Photon Counting technology (TCSPC) is developed. A Geiger-mode avalanche photodiode (G-APD), which has the ability of detecting single-photon events, is used to capture the weak light scattered from the long-range target. In order to improve the ranging resolution of TCSPC based measurement system, a high repetition frequency of subnanosecond narrow pulse generator circuit based on the avalanche effect of RF-BJT is designed and applied as the light source. Moreover, some optimized optical light designs have been done to improve the system signal to noise rate (SNR), including using a special aspherical lens as projecting lens, adopting a telephoto camera lens with small view angle and short depth of field before detector. Experimental tests for evaluation of the laser raging system performance are described. As a means of echo signal analysis, three different algorithms have been introduced, in which the cross-correlation algorithm was demonstrated to be the most effective algorithm to determining the round trip time to a target, even based on histograms with a significant amount of background noise photons. It was found that centimeter ranging resolution can be achieved thanks to the use of Time-to-Digital Converter (TDC) with picosecond resolution and the Cross-Correlation algorithm. The proposed laser ranging system has advantages of high range resolution, short response time and simple structure, which was potential applications for 3D object recognition, computer vision, reverse engineering and virtual reality.

  9. Analysis of En Route Operational Errors: Probability of Resolution and Time-On-Position

    DTIC Science & Technology

    2012-02-01

    control operational errors (OEs). While OE rates tell us about the frequency of occurrence, the rates in and of themselves do not provide a direct...resolution (POR) index and the time-on- position probability (TOPP) index. Whereas the POR is a measure of OE containment (i.e., resolving a loss of...separation before the situation worsens), the TOPP is a measure of the occupational risk of an OE occurring due to traffic exposure. In this report

  10. Attenuation estimation using the peak frequency method with high-resolution time-frequency transforms

    NASA Astrophysics Data System (ADS)

    Tary, J. B.; Van der Baan, M.; Herrera, R. H.

    2016-12-01

    Seismic waves attenuate during their propagation due to Earth anelasticity. Attenuation is usually estimated by frequency domain methods such as the spectral ratio and frequency shift methods. These methods compare large frequency bandwidths of the spectra of two waveforms to compute attenuation. Time-frequency distribution resulting from high-resolution time-frequency transforms are highly localized which prevent their use to compute attenuation with these methods.The peak frequency method only requires the estimation of peak frequencies for a pair of waveforms to estimate attenuation, which is then compatible with high-resolution transforms. We here employ three transforms, namely basis pursuit, synchrosqueezing transform, and complete ensemble empirical mode decomposition (CEEMD). We evaluate their performance regarding attenuation estimation using synthetic examples with different signal-to-noise ratios, and compare their results to those of the spectral ratio and frequency shift methods. In most cases basis pursuit and the synchrosqueezing transform provide accurate results, while CEEMD show a higher sensitivity to the presence of noise.We then apply the three high-resolution transforms and the peak frequency method to two case studies, a seismic reflection profile and a vertical seismic profile (VSP). We employ centroid frequencies instead of peak frequencies because they provide stabler frequency estimates which are then transferred to stabler attenuation estimates. In the case of the seismic reflection profile, the three time-frequency transforms show small increases in centroid frequencies superimposed on a general decreasing trend. This likely corresponds to local tuning effects due to the layering superimposed on the effect of intrinsic attenuation. For the VSP, the three time-frequency transforms show consistent patterns in centroid frequencies and quality factors. These results show the worth of high-resolution transforms for attenuation estimation.

  11. Evaluation of real-time high-resolution MM5 predictions over the Great Lakes region

    Treesearch

    Shiyuan Zhong; Hee-Jin In; Xindi Bian; Joseph Charney; Warren Heilman; Brian. Potter

    2005-01-01

    Real-time high-resolution mesoscale predictions using the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) over the Great Lakes region are evaluated for the 2002/03 winter and 2003 summer seasons using surface and upper-air observations, with a focus on near-surface and boundary layer properties that are important for applications such as air...

  12. Timing of clinical improvement and symptom resolution in the treatment of major depressive disorder.

    PubMed

    Papakostas, George I; Petersen, Timothy; Sklarsky, Katherine G; Nierenberg, Andrew A; Alpert, Jonathan E; Fava, Maurizio

    2007-01-15

    The goal of the present work is to assess for the relationship between the timing of clinical improvement and the resolution of depressive symptoms in Major Depressive Disorder (MDD). 182 MDD outpatients (40.5+/-9.7 years; 53.8% female) who responded following an 8-week, 20 mg, open trial of fluoxetine were included in the analysis. The symptoms questionnaire (SQ) and Beck hopelessness scale (BHS) were also administered to 83 and 153 of these patients, respectively. Onset of clinical improvement was defined as a 30% decrease in 17-item Hamilton depression scale (HDRS-17) scores. Controlling for baseline symptom severity, we then assessed for the relationship between the timing of clinical improvement and depressive symptom at endpoint. Earlier clinical improvement in responders predicted lower HDRS-17, BHS, SQ-depression, SQ-anxiety, but not SQ-somatic symptom or SQ-anger/hostility scores at week 8. This was true regardless of whether improvement was defined as a continuous measure (30% decrease in symptom severity), as a dichotomous measure (clinical response occurring in the first two weeks of treatment). In conclusion, earlier clinical improvement with fluoxetine treatment is predictive of greater symptom resolution at endpoint. Further studies exploring the impact of various treatment modalities and placebo on the timing of clinical improvement and symptom resolution in MDD are warranted.

  13. High-resolution real-time 3D shape measurement on a portable device

    NASA Astrophysics Data System (ADS)

    Karpinsky, Nikolaus; Hoke, Morgan; Chen, Vincent; Zhang, Song

    2013-09-01

    Recent advances in technology have enabled the acquisition of high-resolution 3D models in real-time though the use of structured light scanning techniques. While these advances are impressive, they require large amounts of computing power, thus being limited to using large desktop computers with high end CPUs and sometimes GPUs. This is undesirable in making high-resolution real-time 3D scanners ubiquitous in our mobile lives. To address this issue, this work describes and demonstrates a real-time 3D scanning system that is realized on a mobile device, namely a laptop computer, which can achieve speeds of 20fps 3D at a resolution of 640x480 per frame. By utilizing a graphics processing unit (GPU) as a multipurpose parallel processor, along with a parallel phase shifting technique, we are able to realize the entire 3D processing pipeline in parallel. To mitigate high speed camera transfer problems, which typically require a dedicated frame grabber, we make use of USB 3.0 along with direct memory access (DMA) to transfer camera images to the GPU. To demonstrate the effectiveness of the technique, we experiment with the scanner on both static geometry of a statue and dynamic geometry of a deforming material sample in front of the system.

  14. 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.

  15. 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.

  16. Digitial readout for microwave kinetic inductance detectors and applications in high time resolution astronomy

    NASA Astrophysics Data System (ADS)

    Strader, Matthew James

    This dissertation spans two topics relating to optical to near-infrared astronomical cameras built around Microwave Kinetic Inductance Detectors (MKIDs). The first topic is the development of a digital readout system for 10- to 30-kilopixel arrays of MKIDs. MKIDs are superconducting detectors that can detect individual photons with a wide range of wavelengths with high time resolution (SI{2}{micro s}) and low energy resolution. The advantage of MKIDs over other low temperature detectors with similar capabilities is that it is relatively straightforward to multiplex MKIDs into large arrays. All the complexity of readout is in room temperature electronics. This work discusses the implementation and programming of these electronics. The second part of this work demonstrates the capabilities of the prototype optical and near-infrared MKID instrument with observations of pulsars. Detecting optical pulsations in these objects require high time resolution and low noise. The discovery of a correlation between the brightness of optical pulses from the Crab pulsar and the time of arrival of coincident giant radio pulses is presented. The search for optical pulses from a millisecond pulsar J0337+1715 is discussed along with a new upper limit on the brightness of its optical pulses.

  17. 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.

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

    NASA Image and Video Library

    1993-12-06

    S61-E-017 (6 Dec 1993) --- Astronaut F. Story Musgrave uses one of the handrails on the Hubble Space Telescope (HST) during the second of his three sessions of STS-61 extravehicular activity (EVA-3). Astronauts Musgrave and Jeffrey A. Hoffman used this particular EVA to change out the Wide Field/Planetary Camera (WF/PC) and two magnetometers (also known as magnetic sensing systems). The photo was recorded with the Electronic Still Camera (ESC) inside Endeavour's cabin. Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

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

    NASA Image and Video Library

    1993-12-06

    S61-E-016 (6 Dec 1993) --- Astronaut Jeffrey A. Hoffman (frame center) remains secured by his feet on the end of Endeavour's robot arm as he prepares to participate in the replacement of Hubble Space Telescope's Wide Field/Planetary Camera (WF/PC). Astronaut F. Story Musgrave (just in frame at lower left corner) assists Hoffman in removing the new camera (WFPC-II) from the Scientific Instrument Protective Enclosure (SIPE). Electronic still photography is a relatively new technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality. The electronic still camera has flown as an experiment on several other shuttle missions.

  20. 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.

  1. Temporal Resolution in Time Series and Probabilistic Models of Renewable Power Systems

    NASA Astrophysics Data System (ADS)

    Hoevenaars, Eric

    There are two main types of logistical models used for long-term performance prediction of autonomous power systems: time series and probabilistic. Time series models are more common and are more accurate for sizing storage systems because they are able to track the state of charge. However, the computational time is usually greater than for probabilistic models. It is common for time series models to perform 1-year simulations with a 1-hour time step. This is likely because of the limited availability of high resolution data and the increase in computation time with a shorter time step. Computation time is particularly important because these types of models are often used for component size optimization which requires many model runs. This thesis includes a sensitivity analysis examining the effect of the time step on these simulations. The results show that it can be significant, though it depends on the system configuration and site characteristics. Two probabilistic models are developed to estimate the temporal resolution error of a 1-hour simulation: a time series/probabilistic model and a fully probabilistic model. To demonstrate the application of and evaluate the performance of these models, two case studies are analyzed. One is for a typical residential system and one is for a system designed to provide on-site power at an aquaculture site. The results show that the time series/probabilistic model would be a useful tool if accurate distributions of the sub-hour data can be determined. Additionally, the method of cumulant arithmetic is demonstrated to be a useful technique for incorporating multiple non-Gaussian random variables into a probabilistic model, a feature other models such as Hybrid2 currently do not have. The results from the fully probabilistic model showed that some form of autocorrelation is required to account for seasonal and diurnal trends.

  2. A high-resolution, multi-stop, time-to-digital converter for nuclear time-of-flight measurements

    NASA Astrophysics Data System (ADS)

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

    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.

  3. 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.

  4. Improved-Resolution, Real-Time Skin-Dose Mapping for Interventional Fluoroscopic Procedures

    PubMed Central

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

    2014-01-01

    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. PMID:25177446

  5. Video super-resolution: from QVGA to HD in real-time

    NASA Astrophysics Data System (ADS)

    Mudigoudar, Raj; Bagal, Srinath; Yue, Zhanfeng; Lakshmi, Pramod; Topiwala, Pankaj

    2009-08-01

    In surveillance, reconnaissance and numerous other video applications, enhancing the resolution and quality enhances the usability of captured video. In many such applications, video is often acquired from low cost legacy sensors that offer low resolution due to modest optics and low-resolution arrays, providing imagery that may be grainy and missing important details - and still face transmission bottlenecks. Many post-processing techniques have been proposed to enhance the quality of the video and superresolution is one such technique. In this paper, we extend previous work on a real-time superresolution application implemented in ASIC/FPGA hardware. A gradient based technique is used to register the frames at the sub-pixel level. Once we get the high resolution grid, we use an improved regularization technique in which the image is iteratively modified by applying back-projection to get a sharp and undistorted image. The matlab/simulink proven algorithm was migrated to hardware, to achieve 320x240 -> 1280x960, at more than 38 fps, a stunning superresolution by 16X in total pixels. This significant advance beyond real-time is the main contribution of this paper. Additionally the algorithm is implemented in C to achieve real-time performance in software with optimization for Intel I7 processor. Fixed 32 bit processing structure is used to achieve easy migration across platforms. This gives us a fine balance between the quality and performance. The proposed system is robust and highly efficient. Superresolution greatly decreases camera jitter to deliver a smooth, stabilized, high quality video.

  6. Exploring the Resolution of Time-Lapse Microgravity at an Aquifer Storage and Recovery Site

    NASA Astrophysics Data System (ADS)

    Bradley, C. C.; Ali, M.; Levannier, A.

    2008-12-01

    Time-Lapse Microgravity can reveal relatively small underground fluid displacements via the redistribution of density-contrast at fluid boundaries. The method has, for example, been successfully demonstrated in underground natural gas storage and carbon sequestration studies, and has clear potential for hydrological research and applications such as mining and hydrocarbon reservoir management. For surveys based on modern spring-type gravimeters, the technique's basic measurement resolution is limited by instrument drift, offset errors, and viscoelastic strain hysteresis of the sensor. Despite the sophistication of modern instruments, actual field performance of gravimeters still depends on operator technique and survey conditions. To explore the ultimate resolution of field microgravity (and time-lapse measurements, in particular), we have made repeated gravity surveys of a shallow aquifer storage and recovery test site in the UAE, where injection produces a 'water mound' - localized vertical water-level shifts - monitored by a set of instrumented wells. Based on field measurements and additional laboratory testing of our Scintrex CG-5 gravimeter, we find that the main limit on measurement resolution is from orientation strain hysteresis - a variable amplitude error that decays in approximately 30 minutes, typically in response to orientation during transport between measurement stations. Still, carefully conducted surveys (during the summer, in the desert conditions of the UAE) demonstrate time-lapse microgravity resolution of about 3 microGals, corresponding to a water-level shift of about 0.3 m for this aquifer. In this paper, we will discuss what a 'careful survey' requires and present our detailed testing and survey results.

  7. High resolution real-time projection display using a half-overlap-pixel method

    NASA Astrophysics Data System (ADS)

    Li, Xin; Liu, Juan; Wang, Yongtian

    2017-08-01

    A high resolution real-time projection display was realized by a half-overlap-pixel method in which the intensity was determined by two phase-only computer generated holograms that were obtained analytically. The basic principle of the method is introduced and the numerical simulations that were performed are explained. The results verified that an accurate intensity distribution was achieved successfully with high quality, and the calculation speed was fast enough for real time display. We suggest that it is potentially a promising approach for future displays.

  8. High spatial resolution shortwave infrared imaging technology based on time delay and digital accumulation method

    NASA Astrophysics Data System (ADS)

    Jia, Jianxin; Wang, Yueming; Zhuang, Xiaoqiong; Yao, Yi; Wang, Shengwei; Zhao, Ding; Shu, Rong; Wang, Jianyu

    2017-03-01

    Shortwave infrared (SWIR) imaging technology attracts more and more attention by its fascinating ability of penetrating haze and smoke. For application of spaceborne remote sensing, spatial resolution of SWIR is lower compared with that of visible light (VIS) wavelength. It is difficult to balance between the spatial resolution and signal to noise ratio (SNR). Some conventional methods, such as enlarging aperture of telescope, image motion compensation, and analog time delay and integration (TDI) technology are used to gain SNR. These techniques bring in higher cost of satellite, complexity of system or other negative factors. In this paper, time delay and digital accumulation (TDDA) method is proposed to achieve higher spatial resolution. The method can enhance the SNR and non-uniformity of system theoretically. A prototype of SWIR imager consists of opto-mechanical, 1024 × 128 InGaAs detector, and electronics is designed and integrated to prove TDDA method. Both of measurements and experimental results indicate TDDA method can promote SNR of system approximated of the square root of accumulative stage. The results exhibit that non-uniformity of system is also improved by this approach to some extent. The experiment results are corresponded with the theoretical analysis. Based on the experiments results, it is proved firstly that the goal of 1 m ground sample distance (GSD) in orbit of 500 km is feasible with the TDDA stage of 30 for SWIR waveband (0.9-1.7 μm).

  9. High-resolution, time-lapse imaging for ecosystem-scale phenotyping in the field.

    PubMed

    Brown, Tim; Zimmermann, Christopher; Panneton, Whitney; Noah, Nina; Borevitz, Justin

    2012-01-01

    The high spatial and temporal resolution of data required for high-throughput phenotyping has typically been all but impossible to obtain in field populations of plants. When studies of individual and population genetic variation and microclimate sensor data are combined with phenology data, a landscape-level view of how populations respond to changing environments can be obtained. This chapter will discuss the development of a multi-billion pixel ("gigapixel") camera system that enables the collection of phenology data at up to hourly intervals from in situ plant populations. Such gigapixel time-lapse imaging systems represent a key technological advancement for enabling high-throughput phenotyping in field settings. Gigapixel resolution image datasets allow researchers to record life-history (phenology) data across an entire landscape over multiple seasons. Image data can be wirelessly transmitted to a remote server where it can be accessed online within hours of capture. The time-lapse panoramic images are browsable through an interactive web tool that can be used to compare plant phenology with environmental sensor data collected simultaneously from the field. The high spatial and temporal resolution data can be used to identify individual plant phenology, which can in turn be used to generate complete population level phenotype data. The Gigavision platform is especially powerful when coupled with next-generation population genomic analysis. The Gigavision system permits the rapid identification of the phenotypes and genotypes responding to natural selection in wild populations.

  10. 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.

  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. 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.

  13. 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.

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

    SciTech Connect

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

    2016-03-25

    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 Fe{sup 8+}, Fe{sup 9+} and Fe{sup 10+} 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{sup −1} at proton velocities of 500 km s{sup −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.

  15. From maps to movies: High resolution time-varying sensitivity analysis for spatially distributed watershed models

    NASA Astrophysics Data System (ADS)

    Herman, J. D.; Kollat, J. B.; Reed, P. M.; Wagener, T.

    2013-12-01

    Distributed watershed models are now widely used in practice to simulate runoff responses at high spatial and temporal resolutions. Counter to this purpose, diagnostic analyses of distributed models currently aggregate performance measures in space and/or time and are thus disconnected from the models' operational and scientific goals. To address this disconnect, this study contributes a novel approach for computing and visualizing time-varying global sensitivity indices for spatially distributed model parameters. The high-resolution model diagnostics employ the method of Morris to identify evolving patterns in dominant model processes at sub-daily timescales over a six-month period. The method is demonstrated on the United States National Weather Service's Hydrology Laboratory Research Distributed Hydrologic Model (HL-RDHM) in the Blue River watershed, Oklahoma, USA. Three hydrologic events are selected from within the six-month period to investigate the patterns in spatiotemporal sensitivities that emerge as a function of forcing patterns as well as wet-to-dry transitions. Surprisingly, events with similar magnitudes and durations exhibit significantly different performance controls in space and time, indicating that the diagnostic inferences drawn from representative events will be heavily biased by the a priori selection of those events. By contrast, this study demonstrates high-resolution time-varying sensitivity analysis, requiring no assumptions regarding representative events and allowing modelers to identify transitions between modeled hydrologic regimes a posteriori. The proposed approach details the dynamics of parameter sensitivity in nearly continuous time, providing critical diagnostic insights into the underlying model processes driving predictions. Furthermore, the approach offers the potential to identify transition points between hydrologic regimes under nonstationarity.

  16. From maps to movies: high resolution time-varying sensitivity analysis for spatially distributed watershed models

    NASA Astrophysics Data System (ADS)

    Herman, J. D.; Kollat, J. B.; Reed, P. M.; Wagener, T.

    2013-08-01

    Distributed watershed models are now widely used in practice to simulate runoff responses at high spatial and temporal resolutions. Counter to this purpose, diagnostic analyses of distributed models currently aggregate performance measures in space and/or time and are thus disconnected from the models' operational and scientific goals. To address this disconnect, this study contributes a novel approach for computing and visualizing time-varying global sensitivity indices for spatially distributed model parameters. The high-resolution model diagnostics employ the method of Morris to identify evolving patterns in dominant model processes at sub-daily timescales over a six-month period. The method is demonstrated on the United States National Weather Service's Hydrology Laboratory Research Distributed Hydrologic Model (HL-RDHM) in the Blue River watershed, Oklahoma, USA. Three hydrologic events are selected from within the six-month period to investigate the patterns in spatiotemporal sensitivities that emerge as a function of forcing patterns as well as wet-to-dry transitions. Surprisingly, events with similar magnitudes and durations exhibit significantly different performance controls in space and time, indicating that the diagnostic inferences drawn from representative events will be heavily biased by the a priori selection of those events. By contrast, this study demonstrates high-resolution time-varying sensitivity analysis, requiring no assumptions regarding representative events and allowing modelers to identify transitions between modeled hydrologic regimes a posteriori. The proposed approach details the dynamics of parameter sensitivity in nearly continuous time, providing critical diagnostic insights into the underlying model processes driving predictions. Furthermore, the approach offers the potential to identify transition points between hydrologic regimes under nonstationarity.

  17. Enabling high grayscale resolution displays and accurate response time measurements on conventional computers.

    PubMed

    Li, Xiangrui; Lu, Zhong-Lin

    2012-02-29

    Display systems based on conventional computer graphics cards are capable of generating images with 8-bit gray level resolution. However, most experiments in vision research require displays with more than 12 bits of luminance resolution. Several solutions are available. Bit++ (1) and DataPixx (2) use the Digital Visual Interface (DVI) output from graphics cards and high resolution (14 or 16-bit) digital-to-analog converters to drive analog display devices. The VideoSwitcher (3) described here combines analog video signals from the red and blue channels of graphics cards with different weights using a passive resister network (4) and an active circuit to deliver identical video signals to the three channels of color monitors. The method provides an inexpensive way to enable high-resolution monochromatic displays using conventional graphics cards and analog monitors. It can also provide trigger signals that can be used to mark stimulus onsets, making it easy to synchronize visual displays with physiological recordings or response time measurements. Although computer keyboards and mice are frequently used in measuring response times (RT), the accuracy of these measurements is quite low. The RTbox is a specialized hardware and software solution for accurate RT measurements. Connected to the host computer through a USB connection, the driver of the RTbox is compatible with all conventional operating systems. It uses a microprocessor and high-resolution clock to record the identities and timing of button events, which are buffered until the host computer retrieves them. The recorded button events are not affected by potential timing uncertainties or biases associated with data transmission and processing in the host computer. The asynchronous storage greatly simplifies the design of user programs. Several methods are available to synchronize the clocks of the RTbox and the host computer. The RTbox can also receive external triggers and be used to measure RT with respect

  18. TIME-VARYING POTASSIUM IN HIGH-RESOLUTION SPECTRA OF THE TYPE IA SUPERNOVA 2014J

    SciTech Connect

    Graham, M. L.; Weiss, L. M.; Shen, K. J.; Kelly, P. L.; Zheng, W.; Filippenko, A. V.; Marcy, G. W.; Valenti, S.; Howell, D. A.; Fulton, B. J.; Burt, J.; Rivera, E. J.

    2015-03-10

    We present a time series of the highest resolution spectra yet published for the nearby Type Ia supernova (SN Ia) 2014J in M82. They were obtained at 11 epochs over 33 days around peak brightness with the Levy Spectrograph (resolution R ≈ 110,000) on the 2.4 m Automated Planet Finder telescope at Lick Observatory. We identify multiple Na i D and K i absorption features as well as absorption by Ca ii H and K and several of the more common diffuse interstellar bands (DIBs). We see no evolution in any component of Na i D, Ca ii, or in the DIBs, but do establish the dissipation/weakening of the two most blueshifted components of K i. We present several potential physical explanations, finding the most plausible to be photoionization of circumstellar material, and discuss the implications of our results with respect to the progenitor scenario of SN 2014J.

  19. 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.

  20. A high-resolution time-of-flight mass spectrometer for the detection of ultracold molecules

    NASA Astrophysics Data System (ADS)

    Kraft, S. D.; Mikosch, J.; Staanum, P.; Deiglmayr, J.; Lange, J.; Fioretti, A.; Wester, R.; Weidemüller, M.

    2007-12-01

    We have realized a high-resolution time-of-flight mass spectrometer combined with a magneto-optical trap. The spectrometer enables excellent optical access to the trapped atomic cloud using specifically devised acceleration and deflection electrodes. The ions are extracted along a laser beam axis and deflected onto an off-axis detector. The setup is applied to detect atoms and molecules photoassociated from ultracold atoms. The detection is based on resonance-enhanced multi-photon ionization. Mass resolution up to m/Δmrms=1000 at the mass of 133Cs is achieved. The performance of this spectrometer is demonstrated in the detection of photoassociated ultracold 7Li133Cs molecules near a large signal of 133Cs ions.

  1. 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).

  2. High-resolution reflecting time-of-flight momentum and energy mapping system

    SciTech Connect

    Wang Chao; Kang Yifan; Weaver, Larry; Chang Zenghu

    2009-07-15

    A new system to map electron momentum and energy is proposed. A reflecting electrode is introduced into a time-of-flight (TOF) system whose decelerating electric field sends all the electrons back to a position-sensitive detector close to but behind the source of the electrons. The longer flying distance that results makes it possible to significantly improve the energy-resolved performance, especially in the higher energy region. The dependence of the new TOF system on its characteristic parameters is analyzed, along with its application to attosecond streak cameras. Experimental results verified a relative energy resolution better than 0.2 eV for 22 eV electrons and also revealed the availability of the improved relative energy resolution smaller than 1.0% for electron energy ranging from 30 to 40 eV.

  3. 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.

  4. Detecting shifts in gene regulatory networks during time-course experiments at single-time-point temporal resolution.

    PubMed

    Takenaka, Yoichi; Seno, Shigeto; Matsuda, Hideo

    2015-10-01

    Comprehensively understanding the dynamics of biological systems is one of the greatest challenges in biology. Vastly improved biological technologies have provided vast amounts of information that must be understood by bioinformatics and systems biology researchers. Gene regulations have been frequently modeled by ordinary differential equations or graphical models based on time-course gene expression profiles. The state-of-the-art computational approaches for analyzing gene regulations assume that their models are same throughout time-course experiments. However, these approaches cannot easily analyze transient changes at a time point, such as diauxic shift. We propose a score that analyzes the gene regulations at each time point. The score is based on the information gains of information criterion values. The method detects the shifts in gene regulatory networks (GRNs) during time-course experiments with single-time-point resolution. The effectiveness of the method is evaluated on the diauxic shift from glucose to lactose in Escherichia coli. Gene regulation shifts were detected at two time points: the first corresponding to the time at which the growth of E. coli ceased and the second corresponding to the end of the experiment, when the nutrient sources (glucose and lactose) had become exhausted. According to these results, the proposed score and method can appropriately detect the time of gene regulation shifts. The method based on the proposed score provides a new tool for analyzing dynamic biological systems. Because the score value indicates the strength of gene regulation at each time point in a gene expression profile, it can potentially infer hidden GRNs from time-course experiments.

  5. RMS Emittance Measurements Using Optical Transition Radiation Interferometry at the Jefferson Lab FEL

    SciTech Connect

    M. A. Holloway; S. V. Benson; W. Brock; J. L. Coleman; D. Douglas; R. Evans; P. Evtushenko; K. Jordan; D. W. Sexton; R. B. Fiorito; P. G. O'Shea; A. G. Shkvarunets

    2007-08-01

    Optical Transition Radiation Interferometry (OTRI) has proven to be effective tool for measuring rms beam divergence. We present rms emittance measurement results of the 115 MeV energy recovery linac at the Thomas Jefferson National Laboratories Free electron Laser using OTRI. OTRI data from both near field beam images and far field angular distribution images give evidence of two spatial and angular distributions within the beam. Using the unique features of OTRI we segregate the two distributions of the beam and estimate separate rms emittance values for each component.

  6. 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).

  7. High-resolution intracellular viscosity measurement using time-dependent fluorescence anisotropy.

    PubMed

    Parker, Wesley C; Chakraborty, Nilay; Vrikkis, Regina; Elliott, Gloria; Smith, Stuart; Moyer, Patrick J

    2010-08-02

    A low-cost pulsed laser is used in conjunction with a homebuilt laser confocal-scanning epifluorescence microscope having submicron lateral and axial spatial resolution to determine cytoplasmic viscosity at specific intracytoplasmic locations in J774 mouse macrophage cells. Time-dependent fluorescence anisotropy measurements are made at each location and global deconvolution techniques are used to determine rotational correlation times. These rotational correlation times are related to the hydrated volume of 8-hydroxyperene-1,3,6-trisulfonic acid (HPTS) to calculate viscosity at specific points inside the cell. In the cytoplasmic areas measured, rotational correlation times of HPTS ranged from 0.186 ns to 0.411 ns, corresponding to viscosities ranging from 1.00 +/- 0.03 cP to 2.21+/- 0.05 cP.

  8. 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).

  9. High time resolution measurements of the thermosphere from Fabry-Perot Interferometer measurements of atomic oxygen

    NASA Astrophysics Data System (ADS)

    Ford, E. A. K.; Aruliah, A. L.; Griffin, E. M.; McWhirter, I.

    2007-06-01

    Recent advances in the performance of CCD detectors have enabled a high time resolution study of the high latitude upper thermosphere with Fabry-Perot Interferometers (FPIs) to be performed. 10-s integration times were used during a campaign in April 2004 on an FPI located in northern Sweden in the auroral oval. The FPI is used to study the thermosphere by measuring the oxygen red line emission at 630.0 nm, which emits at an altitude of approximately 240 km. Previous time resolutions have been 4 min at best, due to the cycle of look directions normally observed. By using 10 s rather than 40 s integration times, and by limiting the number of full cycles in a night, high resolution measurements down to 15 s were achievable. This has allowed the maximum variability of the thermospheric winds and temperatures, and 630.0 nm emission intensities, at approximately 240 km, to be determined as a few minutes. This is a significantly greater variability than the often assumed value of 1 h or more. A Lomb-Scargle analysis of this data has shown evidence of gravity wave activity with waves with short periods. Gravity waves are an important feature of mesosphere-lower thermosphere (MLT) dynamics, observed using many techniques and providing an important mechanism for energy transfer between atmospheric regions. At high latitudes gravity waves may be generated in-situ by localised auroral activity. Short period waves were detected in all four clear nights when this experiment was performed, in 630.0 nm intensities and thermospheric winds and temperatures. Waves with many periodicities were observed, from periods of several hours, down to 14 min. These waves were seen in all parameters over several nights, implying that this variability is a typical property of the thermosphere.

  10. 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

  11. Angular versus spatial resolution trade-offs for diffusion imaging under time constraints

    PubMed Central

    Zhan, Liang; Jahanshad, Neda; Ennis, Daniel B.; Jin, Yan; Bernstein, Matthew A.; Borowski, Bret J.; Jack, Clifford R.; Toga, Arthur W.; Leow, Alex D.; Thompson, Paul M.

    2012-01-01

    Diffusion weighted magnetic resonance imaging (DW-MRI) are now widely used to assess brain integrity in clinical populations. The growing interest in mapping brain connectivity has made it vital to consider what scanning parameters affect the accuracy, stability, and signal-to-noise of Diffusion measures. Trade-offs between scan parameters can only be optimized if their effects on various commonly derived measures are better understood. To explore angular versus spatial resolution trade-offs in standard tensor-derived measures, and in measures that use the full angular information in diffusion signal, we scanned eight subjects twice, two weeks apart, using three protocols that took the same amount of time (7 minutes). Scans with 3, 2.7, 2.5 mm isotropic voxels were collected using 48, 41, and 37 diffusion-sensitized gradients to equalize scan times. A specially designed DTI phantom was also scanned with the same protocols, and different b-values. We assessed how several diffusion measures including fractional anisotropy (FA), mean diffusivity (MD), and the full 3D orientation distribution function (ODF) depended on the spatial/angular resolution and the SNR. We also created maps of stability over time in the FA, MD, ODF, skeleton FA of 14 TBSS-derived ROIs, and an information uncertainty index derived from the tensor distribution function, which models the signal using a continuous mixture of tensors. In scans of the same duration, higher angular resolution and larger voxels boosted SNR and improved stability over time. The increased partial voluming in large voxels also led to bias in estimating FA, but this was partially addressed by using “beyond-tensor” models of diffusion. PMID:22522814

  12. 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

  13. Angular versus spatial resolution trade-offs for diffusion imaging under time constraints.

    PubMed

    Zhan, Liang; Jahanshad, Neda; Ennis, Daniel B; Jin, Yan; Bernstein, Matthew A; Borowski, Bret J; Jack, Clifford R; Toga, Arthur W; Leow, Alex D; Thompson, Paul M

    2013-10-01

    Diffusion weighted magnetic resonance imaging (DW-MRI) are now widely used to assess brain integrity in clinical populations. The growing interest in mapping brain connectivity has made it vital to consider what scanning parameters affect the accuracy, stability, and signal-to-noise of diffusion measures. Trade-offs between scan parameters can only be optimized if their effects on various commonly-derived measures are better understood. To explore angular versus spatial resolution trade-offs in standard tensor-derived measures, and in measures that use the full angular information in diffusion signal, we scanned eight subjects twice, 2 weeks apart, using three protocols that took the same amount of time (7 min). Scans with 3.0, 2.7, 2.5 mm isotropic voxels were collected using 48, 41, and 37 diffusion-sensitized gradients to equalize scan times. A specially designed DTI phantom was also scanned with the same protocols, and different b-values. We assessed how several diffusion measures including fractional anisotropy (FA), mean diffusivity (MD), and the full 3D orientation distribution function (ODF) depended on the spatial/angular resolution and the SNR. We also created maps of stability over time in the FA, MD, ODF, skeleton FA of 14 TBSS-derived ROIs, and an information uncertainty index derived from the tensor distribution function, which models the signal using a continuous mixture of tensors. In scans of the same duration, higher angular resolution and larger voxels boosted SNR and improved stability over time. The increased partial voluming in large voxels also led to bias in estimating FA, but this was partially addressed by using "beyond-tensor" models of diffusion.

  14. 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

  15. Time-reversed ultrasonically encoded optical focusing using two ultrasonic transducers for improved ultrasonic axial resolution.

    PubMed

    Yang, Qiang; Xu, Xiao; Lai, Puxiang; Xu, Daxiong; Wang, Lihong V

    2013-11-01

    Focusing light inside highly scattering media is a challenging task in biomedical optical imaging, manipulation, and therapy. A recent invention has overcome this challenge by time reversing ultrasonically encoded diffuse light to an ultrasound-modulated volume inside a turbid medium. In this technique, a photorefractive (PR) crystal or polymer can be used as the phase conjugate mirror for optical time reversal. Accordingly, a relatively long ultrasound burst, whose duration matches the PR response time of the PR material, is usually used to encode the diffuse light. This long burst results in poor focusing resolution along the acoustic axis. In this work, we propose to use two intersecting ultrasound beams, emitted from two ultrasonic transducers at different frequencies, to modulate the diffuse light at the beat frequency within the intersection volume. We show that the time reversal of the light encoded at the beat frequency can converge back to the intersection volume. Experimentally, an acoustic axial resolution of ~1.1 mm was demonstrated inside turbid media, agreeing with theoretical estimation.

  16. 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.

  17. 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.

  18. 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.

  19. An advection-based model to increase the temporal resolution of PIV time series.

    PubMed

    Scarano, Fulvio; Moore, Peter

    A numerical implementation of the advection equation is proposed to increase the temporal resolution of PIV time series. The method is based on the principle that velocity fluctuations are transported passively, similar to Taylor's hypothesis of frozen turbulence. In the present work, the advection model is extended to unsteady three-dimensional flows. The main objective of the method is that of lowering the requirement on the PIV repetition rate from the Eulerian frequency toward the Lagrangian one. The local trajectory of the fluid parcel is obtained by forward projection of the instantaneous velocity at the preceding time instant and backward projection from the subsequent time step. The trajectories are approximated by the instantaneous streamlines, which yields accurate results when the amplitude of velocity fluctuations is small with respect to the convective motion. The verification is performed with two experiments conducted at temporal resolutions significantly higher than that dictated by Nyquist criterion. The flow past the trailing edge of a NACA0012 airfoil closely approximates frozen turbulence, where the largest ratio between the Lagrangian and Eulerian temporal scales is expected. An order of magnitude reduction of the needed acquisition frequency is demonstrated by the velocity spectra of super-sampled series. The application to three-dimensional data is made with time-resolved tomographic PIV measurements of a transitional jet. Here, the 3D advection equation is implemented to estimate the fluid trajectories. The reduction in the minimum sampling rate by the use of super-sampling in this case is less, due to the fact that vortices occurring in the jet shear layer are not well approximated by sole advection at large time separation. Both cases reveal that the current requirements for time-resolved PIV experiments can be revised when information is poured from space to time. An additional favorable effect is observed by the analysis in the frequency

  20. High Resolution Deformation Time Series Estimation for Distributed Scatterers Using Terrasar-X Data

    NASA Astrophysics Data System (ADS)

    Goel, K.; Adam, N.

    2012-07-01

    In recent years, several SAR satellites such as TerraSAR-X, COSMO-SkyMed and Radarsat-2 have been launched. These satellites provide high resolution data suitable for sophisticated interferometric applications. With shorter repeat cycles, smaller orbital tubes and higher bandwidth of the satellites; deformation time series analysis of distributed scatterers (DSs) is now supported by a practical data basis. Techniques for exploiting DSs in non-urban (rural) areas include the Small Baseline Subset Algorithm (SBAS). However, it involves spatial phase unwrapping, and phase unwrapping errors are typically encountered in rural areas and are difficult to detect. In addition, the SBAS technique involves a rectangular multilooking of the differential interferograms to reduce phase noise, resulting in a loss of resolution and superposition of different objects on ground. In this paper, we introduce a new approach for deformation monitoring with a focus on DSs, wherein, there is no need to unwrap the differential interferograms and the deformation is mapped at object resolution. It is based on a robust object adaptive parameter estimation using single look differential interferograms, where, the local tilts of deformation velocity and local slopes of residual DEM in range and azimuth directions are estimated. We present here the technical details and a processing example of this newly developed algorithm.

  1. Compact hybrid real-time hyperspectral imaging system with high effective spatial, spectral, and temporal resolution

    NASA Astrophysics Data System (ADS)

    Roth, Filip; Abbadi, Ahmad; Herman, Ondrej; Pavelek, Martin; Prenosil, Vaclav

    2016-10-01

    Medical endoscopes for image-guided surgery commonly use standard color image sensors, discarding any more detailed spectral information. Medical spectroscopy devices with various spectral working ranges are specialized to specific medical procedures and in general are not usable for image-guided surgery due to limitations in spatial or temporal resolution. In this paper, we present an initial demonstrator of hyperspectral endoscope, composed of two image sensors with complementing parameters. Using this hybrid approach, combining sensors with different spatial and spectral resolutions and spectral ranges, we obtain improved coverage of all the respective parameters. After digitally processing and merging the video streams, while maintaining the better features of both, we obtain an imaging system providing high effective spatial, spectral, and temporal resolution. The system is based on field programmable gate arrays. It provides real-time video output (60 Hz), which is usable for navigation during image-guided surgery. The flexible system architecture allows for an easy extension of the processing algorithms and enables minimal video signal latency. Physical dimensions and portability of the system are comparable to standard off-the-shelf medical endoscope cameras. The device can output both processed video and standard visible light video signals on one or more video outputs of the system. The resulting processed video signal obtained from the combined image sensor data greatly increases the amount of useful information available to the end user.

  2. RMS Lg as a Yield Estimator in Eurasia. Part 1

    DTIC Science & Technology

    1992-04-01

    with Distance and Station Site Amplifications ........................... 57 Some Concluding Remarks...explosions on 88/12/04 (and for 77/10/20 for station NRI) plotted as a function of epicentral distance and aligned on visually read first arrival times...network magnitudes .......................................... 58 24. Magnitude path corrections as a function of epicentral distance according to phase

  3. 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.

  4. Astronauts Truly and Engle checking RMS instrument in cabin of Columbia

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Astronauts Richard H. Truly and Joe Engle checking RMS instrument in the cabin of orbiter Columbia during the milestone Orbiter Integrated Test (OIT) in the Orbiter Processing Facility (OPF), at the Kennedy Space Center.

  5. Rms characterization of Bessel Gauss beams: Correspondence between polar and Cartesian representations

    NASA Astrophysics Data System (ADS)

    Rousseau, Guy; Gay, David; Piché, Michel

    2006-09-01

    A recent analysis [G. Rousseau, D. Gay and M. Piché, One-dimensional description of cylindrically symmetric laser beams: application to Bessel-type nondiffracting beams, J. Opt. Soc. Am. A, 22 (2005) 1274] has shown that any cylindrically symmetric laser beam can be synthesized from a single wave called a constituent wave. This representation allows the introduction of one-dimensional Cartesian root-mean-square (rms) parameters to describe the conical structure of cylindrically symmetric laser beams. In this paper, we compare the rms characterization of Bessel-Gauss beams in polar coordinates with that of their respective constituent waves in Cartesian coordinates. Numerical results reveal an asymptotic correspondence between polar and Cartesian rms parameters of Bessel-Gauss beams propagating in a nondiffracting regime. Such a correspondence eliminates misleading interpretations about the propagation factor and the Rayleigh range of nondiffracting Bessel-type beams characterized in terms of polar rms parameters.

  6. Astronaut James van Hoften on RMS tracking Syncom IV-3 after deployment

    NASA Image and Video Library

    1985-09-01

    51I-44-081 (1 Sept 1985) --- Astronaut James D. van Hoften on the Discovery's remote manipulator system (RMS) arm visually tracks the distant Syncom IV-3 communications satellite after its second release, on Sept. 1, 1985.

  7. STS 41-D mission specialist Judith Resnik trains on the RMS

    NASA Technical Reports Server (NTRS)

    1983-01-01

    STS 41-D mission specialist Judith Resnik prepares for training on the remote manipulator system (RSM) on board the shuttle mission simulator (SMS). She is on the SMS aft deck facing the RMS translation hand control and overhead starboard window.

  8. Astronaut Anna Fisher practices control of the RMS in a trainer

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Astronaut Anna Lee Fisher, mission specialist for 51-A, practices control of the remote manipulator system (RMS) at a special trainer at JSC. Dr. Fisher is pictured in the manipulator development facility (MDF) of JSC's Shuttle mockup and integration laboratory.

  9. STS 41-D mission specialist Judith Resnik trains on the RMS

    NASA Technical Reports Server (NTRS)

    1983-01-01

    STS 41-D mission specialist Judith Resnik prepares for training on the remote manipulator system (RSM) on board the shuttle mission simulator (SMS). She is on the SMS aft deck facing the RMS translation hand control and overhead starboard window.

  10. Astronaut Anna Fisher practices control of the RMS in a trainer

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Astronaut Anna Lee Fisher, mission specialist for 51-A, practices control of the remote manipulator system (RMS) at a special trainer at JSC. Dr. Fisher is pictured in the manipulator development facility (MDF) of JSC's Shuttle mockup and integration laboratory.

  11. Challengers RMS arm is moved close to the SPAS-01 during proximity operations

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The Shuttle Challenger's remote manipulator system (RMS) arm is moved to within a feet feet of the Shuttle pallet satellite (SPAS-01) during porximity operations. Part of SPAS is obscured by the window edge on the Challenger's flight deck ceiling.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. High-resolution imaging characterization of bladder dynamic morphophysiology by time-lapse optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Pan, Y. T.; Wu, Q.; Wang, Z. G.; Brink, P. R.; Du, C. W.

    2005-09-01

    We report an experimental study of the possibility of high-speed optical coherence tomography (OCT) for high-resolution imaging characterization of detrusor dynamic morphophysiology and analysis of the mechanisms that lead to geriatric incontinence (GI). The spontaneous contractility of intact fresh rabbit bladders was imaged with two-dimensional (2D) OCT ex vivo at up to 8frames/s. The time-lapse 2D OCT images were postprocessed by image segmentation and fast-Fourier-transform analysis to characterize the dynamic morphological changes of the bladder contractility. In addition, we studied young and aging rat bladders to analyze the differences in dynamics. Preliminary results of our ex vivo study reveal that time-lapse OCT can track the contractile waves of bladders at high spatial resolution and characterize their dynamic morphophysiology in terms of amplitude, phase, and frequency. The results suggest that time-lapse OCT has the potential to act as a detrusor optical biopsy to enhance the diagnosis of detrusor dysfunction and thus of the mechanisms that lead to GI.

  18. A Bichromator for High Time Resolution Measurements of Stark Broadened Pellet Ablation Light

    NASA Astrophysics Data System (ADS)

    Schmidt, G. L.; Baylor, L. R.; Fehling, D. T.; Jernigan, T. C.; Brooks, N. H.; Parks, P. B.

    2004-11-01

    Details of the pellet/plasma interaction are important for modeling of local pellet source rates and cross field transport of pellet mass. Understanding these processes is critical for projection of current fueling experiments to future devices such as ITER. Measurement of the Stark broadened deuterium emission lines provides the electron density and temperature of the pellet cloud for comparison with modeling details. Stark broadening measurements on JET for low field launch pellets at moderate time resolution indicate a slow variation in the cloud parameters. Observations of ablation light suggest changes in cloud parameters may occur on faster time scales. We report on the possible application of a multiple interference filter technique[1]to allow monitoring of cloud parameters at time resolution sufficient to study both the slow and rapid variations in cloud parameters. Application of the bichromator to line widths and temporal evolution typical of DIII-D pellet injection cases will be discussed.[1]McNeill,D.H.,RSI 73 (2002) 3193.

  19. 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)

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

    NASA Astrophysics Data System (ADS)

    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

    2013-04-01

    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 (10-4 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 10-15 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.

  1. 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.

  2. Resolution enhancement and separation of reverberation from target echo with the time reversal operator decomposition

    NASA Astrophysics Data System (ADS)

    Folégot, Thomas; Prada, Claire; Fink, Mathias

    2003-06-01

    Time reversal operator (TRO) decompositions are performed in a model of an ocean wave guide containing a target and having different kinds of bottom. The objective is to study the effects of bottom reverberation and absorption by means of ultrasonic experiments. It is shown experimentally that the echo from a target can be separated from the bottom reverberation. Reverberation eigenvectors are back propagated in the wave guide leading to focus on the bottom. An amplitude correction is applied to both reverberation and signal eigenvectors to compensate for bottom absorption and thus to improve target resolution.

  3. 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.

  4. Occult spinal dysraphism in infants: screening with high-resolution real-time ultrasound.

    PubMed

    Scheible, W; James, H E; Leopold, G R; Hilton, S V

    1983-03-01

    Spinal dysraphism refers to incomplete embryologic development of the dorsal midline. Frequently it is not clinically obvious, and lack of treatment can lead to progressive neurological damage. Early diagnosis of occult defects can allow appropriate surgical intervention and prevent neurological deficits. The authors have used high-resolution real-time ultrasound to screen infants with various cutaneous lumbosacral markers, all of whom were at risk of occult spinal dysraphism. Preliminary results suggest that ultrasound is a reliable screening procedure and could obviate the need for more costly and invasive tests.

  5. 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.

  6. Resolution enhancement and separation of reverberation from target echo with the time reversal operator decomposition.

    PubMed

    Folégot, Thomas; Prada, Claire; Fink, Mathias

    2003-06-01

    Time reversal operator (TRO) decompositions are performed in a model of an ocean wave guide containing a target and having different kinds of bottom. The objective is to study the effects of bottom reverberation and absorption by means of ultrasonic experiments. It is shown experimentally that the echo from a target can be separated from the bottom reverberation. Reverberation eigenvectors are back propagated in the wave guide leading to focus on the bottom. An amplitude correction is applied to both reverberation and signal eigenvectors to compensate for bottom absorption and thus to improve target resolution.

  7. Thyroid imaging: comparison of high-resolution real-time ultrasound and computed tomography

    SciTech Connect

    Radecki, P.D.; Arger, P.H.; Arenson, R.L.; Jennings, A.S.; Coleman, B.G.; Mintz, M.C.; Kressel, H.Y.

    1984-10-01

    High-resolution real-time ultrasound (US) and computed tomography (CT) were compared in 48 patients with a clinical diagnosis of thyroid abnormality and also correlated with biopsy or surgery. The modalities were considered comparable in 38 cases (79%), while CT was superior in 5 and US in 5. Both techniques lacked histopathological specificity. CT appears to be advantageous in detecting substernal thyroid extension and confirming thyroiditis, while the ability of US to detect small nodules makes it the procedure of choice in evaluating suspected intrinsic thyroid abnormalities.

  8. A general resolution of intractable problems in polynomial time through DNA Computing.

    PubMed

    Sanches, C A A; Soma, N Y

    2016-12-01

    Based on a set of known biological operations, a general resolution of intractable problems in polynomial time through DNA Computing is presented. This scheme has been applied to solve two NP-Hard problems (Minimization of Open Stacks Problem and Matrix Bandwidth Minimization Problem) and three co-NP-Complete problems (associated with Hamiltonian Path, Traveling Salesman and Hamiltonian Circuit), which have not been solved with this model. Conclusions and open questions concerning the computational capacity of this model are presented, and research topics are suggested.

  9. The investigation of Martian dune fields using very high resolution photogrammetric measurements and time series analysis

    NASA Astrophysics Data System (ADS)

    Kim, J.; Park, M.; Baik, H. S.; Choi, Y.

    2016-12-01

    At the present time, arguments continue regarding the migration speeds of Martian dune fields and their correlation with atmospheric circulation. However, precisely measuring the spatial translation of Martian dunes has rarely conducted only a very few times Therefore, we developed a generic procedure to precisely measure the migration of dune fields with recently introduced 25-cm resolution High Resolution Imaging Science Experimen (HIRISE) employing a high-accuracy photogrammetric processor and sub-pixel image correlator. The processor was designed to trace estimated dune migration, albeit slight, over the Martian surface by 1) the introduction of very high resolution ortho images and stereo analysis based on hierarchical geodetic control for better initial point settings; 2) positioning error removal throughout the sensor model refinement with a non-rigorous bundle block adjustment, which makes possible the co-alignment of all images in a time series; and 3) improved sub-pixel co-registration algorithms using optical flow with a refinement stage conducted on a pyramidal grid processor and a blunder classifier. Moreover, volumetric changes of Martian dunes were additionally traced by means of stereo analysis and photoclinometry. The established algorithms have been tested using high-resolution HIRISE images over a large number of Martian dune fields covering whole Mars Global Dune Database. Migrations over well-known crater dune fields appeared to be almost static for the considerable temporal periods and were weakly correlated with wind directions estimated by the Mars Climate Database (Millour et al. 2015). Only over a few Martian dune fields, such as Kaiser crater, meaningful migration speeds (>1m/year) compared to phtotogrammetric error residual have been measured. Currently a technical improved processor to compensate error residual using time series observation is under developing and expected to produce the long term migration speed over Martian dune

  10. 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.

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

    NASA Image and Video Library

    1993-06-24

    STS057-84-000AD (24 June 1993) --- The recently "captured" European Retrievable Carrier (EURECA) was recorded on 70mm film as it was berthed in the Space Shuttle Endeavour's aft cargo bay, assisted by the Canadian-built Remote Manipulator System (RMS), partially visible in upper right. Moments later the RMS eased EURECA into its stowage area between Endeavour's aft cargo bay firewall and the SpaceHab module (partially visible in foreground).

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

    NASA Image and Video Library

    1990-01-20

    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.

  13. 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.

  14. Review: Rusticle Formation on the RMS Titanic and the Potential Influence ofOceanography

    DTIC Science & Technology

    2017-01-12

    Abstract Meter length iron-rich rusticles on the RMS Titanic contain bacteria that reportedly mobilize iron from the ship structure at a rate that will...Iron oxidizing bacteria Greenland Ice Sheet Western Boundary Undercurrent Background The Royal Mail Ship (RMS) Titanic sank on April 15, 1912...deepest location. Some investigators have concluded that rusticle formation is the result of biodeterio- ration of steel by bacteria (Cullimore et al. 2002

  15. 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).

  16. 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.

  17. 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.

  18. Quantitative FRET Analysis by Fast Acquisition Time Domain FLIM at High Spatial Resolution in Living Cells

    PubMed Central

    Padilla-Parra, Sergi; Audugé, Nicolas; Coppey-Moisan, Maïté; Tramier, Marc

    2008-01-01

    Quantitative analysis in Förster resonance energy transfer (FRET) experiments in live cells for protein interaction studies is still a challenging issue. In a two-component system (FRET and no FRET donor species), fitting of fluorescence lifetime imaging microscopy (FLIM) data gives the fraction of donor molecules involved in FRET (fD) and the intrinsic transfer efficiency. But when fast FLIM acquisitions are used to monitor dynamic changes in protein-protein interactions at high spatial and temporal resolutions in living cells, photon statistics and time resolution are limited. In this case, fitting procedures are not reliable, even for single lifetime donors. We introduce the new concept of a minimal fraction of donor molecules involved in FRET (mfD), coming from the mathematical minimization of fD. We find particular advantage in the use of mfD because it can be obtained without fitting procedures and it is derived directly from FLIM data. mfD constitutes an interesting quantitative parameter for live cell studies because it is related to the minimal relative concentration of interacting proteins. For multi-lifetime donors, the process of fitting complex fluorescence decays to find at least four reliable lifetimes is a near impossible task. Here, mfD extension for multi-lifetime donors is the only quantitative determinant. We applied this methodology for imaging the interaction between the bromodomains of TAFII250 and acetylated histones H4 in living cells at high resolution. We show the existence of discrete acetylated chromatin domains where the minimal fraction of bromodomain interacting with acetylated H4 oscillates from 0.26 to 0.36 and whose size is smaller than half of one micron cube. We demonstrate that mfD by itself is a useful tool to investigate quantitatively protein interactions in live cells, especially when using fast FRET-FLIM acquisition times. PMID:18539634

  19. 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

  20. Chapter 8: Spatiotemporal dynamics in bacterial cells: real-time studies with single-event resolution.

    PubMed

    Golding, Ido; Cox, Edward C

    2008-01-01

    To produce a quantitative picture of cellular life, one has to study the processes comprising it in individual living cells, quantifying intracellular dynamics with sufficient resolution to describe individual events in space and time. To perform such studies, we have recently developed a novel measurement approach, based on quantitative fluorescence microscopy, and applied it to the study of transcription in Escherichia coli and of the spatiotemporal dynamics of individual mRNA molecules in the cell (Golding and Cox, 2004, 2006a; Golding et al., 2005). The ability to detect individual events in real time depends on the engineering of an endogenous cellular process for amplifying the biological signal, in a way which allows signal detection to be independent of slow and highly stochastic cellular processes (Golding and Cox, 2006a). In this chapter, we describe the ingredients of our system and the way data is acquired and analyzed. We attempt to give general lessons for researchers who wish to implement a similar approach for the study of transcription in other organisms and, more generally, for the study of cellular processes with single-event resolution.

  1. High Time Resolution Measurements of Gaseous Oxidized Mercury from Ground and Aircraft Platforms

    NASA Astrophysics Data System (ADS)

    Lyman, S. N.; Jaffe, D. A.

    2009-12-01

    Atmospheric mercury fractions (gaseous elemental, gaseous oxidized, and fine particulate-bound mercury) have been measured in many different environmental conditions, primarily with the Tekran 2537/1130/1135 speciation system, and these measurements have greatly enhanced scientific understanding of atmospheric mercury dynamics. However, measurements of gaseous oxidized mercury, the most reactive, soluble, and bioavailable mercury fraction, have low time resolution with the Tekran system and have been mostly unchecked by calibration standards. We have developed an alternative technique for measuring gaseous oxidized mercury that provides higher resolution (2.5 minute) measurements, and have built a permeation tube-based oxidized mercury (HgCl2, HgBr2, and HgO) calibrator. The system measures oxidized mercury based on the difference between elemental mercury and total mercury measured with two Tekran 2537 analyzers, and has a 2.5 minute detection limit sufficient to quantify high oxidized mercury events (~80 pg m-3). Additionally, in laboratory tests it outperforms measurements made with KCl-coated denuders in terms of percent recovery and time-averaged detection limit. We have used this system in aircraft and at Mount Bachelor Observatory to observe the origins and dynamics of high oxidized mercury air in the Pacific Northwest, and are preparing it for deployment in the NCAR C-130 for detailed assessment of atmospheric mercury fractions in North America.

  2. 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.

  3. High-speed MCP anodes for high time resolution low-energy charged particle spectrometers

    NASA Astrophysics Data System (ADS)

    Saito, Yoshifumi; Yokota, Shoichiro; Asamura, Kazushi; Krieger, Amanda

    2017-02-01

    The time resolution of low-energy charged particle measurements is becoming higher and higher. In order to realize high time resolution measurements, a 1-D circular delay line anode has been developed as a high-speed microchannel plate (MCP) anode. The maximum count rate of the 1-D circular delay line anode is around 1 × 107/s/360°, which is much higher than the widely used resistive anode, whose maximum count rate is around 1 × 106/s/360°. In order to achieve much higher speeds, an MCP anode with application-specific integrated circuit (ASIC) has been developed. We have decided to adopt an anode configuration in which a discrete anode is formed on a ceramic substrate, and a bare ASIC chip is installed on the back of the ceramic. It has been found that the anode can detect at a high count rate of 2 × 108/s/360°. Developments in both delay line and discrete anodes, as well as readout electronics, will be reviewed.

  4. 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.

  5. Light transmission spectroscopy in real time: a high-resolution nanoparticle analysis instrument.

    PubMed

    Tanner, Carol E; Sun, Nan; Deatsch, Alison; Li, Frank; Ruggiero, Steven T

    2017-03-01

    This paper describes light transmission spectroscopy (LTS), a technique for eliminating spectral noise and systematic effects in real-time spectroscopic measurements. In our work, we combine LTS with spectral inversion for the purpose of nanoparticle analysis. This work employs a wideband multi-wavelength light source and grating spectrometers coupled to CCD detectors. The light source ranges from 210 to 2000 nm, the wavelength-dependent light detection system ranges from 200 to 1100 nm with ≤1  nm resolution, and the nanoparticle diameters range from 1 to 3000 nm. The nanoparticles are suspended in pure water or water-based buffer solutions. For testing and calibration purposes, results are presented for nanoparticles composed of polystyrene and gold. Mie theory is used to model the total extinction cross section, and spectral inversion is employed to obtain quantitative particle size distributions, from which information on the size, shape, and number of nanoparticles can be derived. Discussed are the precision, accuracy, resolution, and sensitivity of our results. The LTS technique is quite versatile and can be applied to spectroscopic investigations where wideband, accurate, low-noise, real-time spectra are desired.

  6. APES: Acute Precipitating Electron Spectrometer - A High Time Resolution Monodirectional Magnetic Deflection Electron Spectrometer

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

    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 x 100 mm), and there was a total of 50 discrete anodes under the MCP, each one 15 mm x 1.5 mm, with a 0.5 mm spacing between anodes. The target energy range of APES was 200 eV to 30 keV.

  7. The High Time Resolution Universe Pulsar Survey - I. System configuration and initial discoveries

    NASA Astrophysics Data System (ADS)

    Keith, M. J.; Jameson, A.; van Straten, W.; Bailes, M.; Johnston, S.; Kramer, M.; Possenti, A.; Bates, S. D.; Bhat, N. D. R.; Burgay, M.; Burke-Spolaor, S.; D'Amico, N.; Levin, L.; McMahon, Peter L.; Milia, S.; Stappers, B. W.

    2010-12-01

    We have embarked on a survey for pulsars and fast transients using the 13-beam multibeam receiver on the Parkes Radio Telescope. Installation of a digital backend allows us to record 400 MHz of bandwidth for each beam, split into 1024 channels and sampled every 64 μs. Limits of the receiver package restrict us to a 340 MHz observing band centred at 1352 MHz. The factor of 8 improvement in frequency resolution over previous multibeam surveys allows us to probe deeper into the Galactic plane for short-duration signals such as the pulses from millisecond pulsars. We plan to survey the entire southern sky in 42641 pointings, split into low, mid and high Galactic latitude regions, with integration times of 4200, 540 and 270 s, respectively. Simulations suggest that we will discover 400 pulsars, of which 75 will be millisecond pulsars. With ~30 per cent of the mid-latitude survey complete, we have redetected 223 previously known pulsars and discovered 27 pulsars, five of which are millisecond pulsars. The newly discovered millisecond pulsars tend to have larger dispersion measures than those discovered in previous surveys, as expected from the improved time and frequency resolution of our instrument.

  8. Time-Optimized High-Resolution Readout-Segmented Diffusion Tensor Imaging

    PubMed Central

    Reishofer, Gernot; Koschutnig, Karl; Langkammer, Christian; Porter, David; Jehna, Margit; Enzinger, Christian; Keeling, Stephen; Ebner, Franz

    2013-01-01

    Readout-segmented echo planar imaging with 2D navigator-based reacquisition is an uprising technique enabling the sampling of high-resolution diffusion images with reduced susceptibility artifacts. However, low signal from the small voxels and long scan times hamper the clinical applicability. Therefore, we introduce a regularization algorithm based on total variation that is applied directly on the entire diffusion tensor. The spatially varying regularization parameter is determined automatically dependent on spatial variations in signal-to-noise ratio thus, avoiding over- or under-regularization. Information about the noise distribution in the diffusion tensor is extracted from the diffusion weighted images by means of complex independent component analysis. Moreover, the combination of those features enables processing of the diffusion data absolutely user independent. Tractography from in vivo data and from a software phantom demonstrate the advantage of the spatially varying regularization compared to un-regularized data with respect to parameters relevant for fiber-tracking such as Mean Fiber Length, Track Count, Volume and Voxel Count. Specifically, for in vivo data findings suggest that tractography results from the regularized diffusion tensor based on one measurement (16 min) generates results comparable to the un-regularized data with three averages (48 min). This significant reduction in scan time renders high resolution (1×1×2.5 mm3) diffusion tensor imaging of the entire brain applicable in a clinical context. PMID:24019951

  9. Impact of rainfall data resolution in time and space on the urban flooding evaluation.

    PubMed

    Notaro, Vincenza; Fontanazza, Chiara Maria; Freni, Gabriele; Puleo, Valeria

    2013-01-01

    Climate change and modification of the urban environment increase the frequency and the negative effects of flooding, increasing the interest of researchers and practitioners in this topic. Usually, flood frequency analysis in urban areas is indirectly carried out by adopting advanced hydraulic models to simulate long historical rainfall series or design storms. However, their results are affected by a level of uncertainty which has been extensively investigated in recent years. A major source of uncertainty inherent to hydraulic model results is linked to the imperfect knowledge of the rainfall input data both in time and space. Several studies show that hydrological modelling in urban areas requires rainfall data with fine resolution in time and space. The present paper analyses the effect of rainfall knowledge on urban flood modelling results. A mathematical model of urban flooding propagation was applied to a real case study and the maximum efficiency conditions for the model and the uncertainty affecting the results were evaluated by means of generalised likelihood uncertainty estimation (GLUE) analysis. The added value provided by the adoption of finer temporal and spatial resolution of the rainfall was assessed.

  10. 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

  11. 32 bin near-infrared time-multiplexing detector with attojoule single-shot energy resolution.

    PubMed

    Eraerds, Patrick; Pomarico, Enrico; Zhang, Jun; Sanguinetti, Bruno; Thew, Rob; Zbinden, Hugo

    2010-10-01

    We present two implementations of photon counting time-multiplexing detectors for near-infrared wavelengths, based on Peltier cooled InGaAs/InP avalanche photodiodes. A first implementation is motivated by practical considerations using only commercially available components. It features 16 bins, pulse repetition rates of up to 22 kHz, and a large range of applicable pulse widths of up to 100 ns. A second implementation is based on rapid gating detectors, permitting dead times below 10 ns. This allows one to realize a high dynamic-range 32 bin detector, able to process pulse repetition rates of up to 6 MHz for pulse widths of up to 200 ps. Analysis of the detector response at 16.5% detection efficiency reveals a single-shot energy resolution on the attojoule level.

  12. 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.

  13. 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.

  14. An Improvement on Space Focusing Resolution in Two-Field Time-of-Flight Mass Spectrometers

    SciTech Connect

    Yildirim, M.; Aydin, R.; Akin, U.; Kilic, H. S.; Sise, O.; Ulu, M.; Dogan, M.

    2007-04-23

    Time-of-Flight Mass Spectrometer (TOFMS) is a sophisticated device for the mass selective analysis of a variety of samples. The main limitation on TOFMS technique is the obtainable resolution where the two main limiting factors are the initial space and energy spread of particles created in ionization region. Similar charged particles starting at different points will reach the detector at different times. So, this problem makes space focusing is very important subject. We have presented principles of two-fields TOFMS with second-order space focusing both using analytical methods and ray-tracing simulation. This work aims understanding of ion optical system clearly and gives hint of expectation for future developments.

  15. Ultrafast electron diffraction: determination of radical structure with picosecond time resolution

    NASA Astrophysics Data System (ADS)

    Cao, J.; Ihee, H.; Zewail, A. H.

    1998-06-01

    Using ultrafast electron diffraction (UED) with the temporal diffraction-difference method recently developed in this laboratory, we report accurate determination of the radical (CF 2) structure in the dissociation of diiododifluoromethane (CF 2I 2) with picosecond time resolution. Time-zero was clocked accurately within 2 ps and both iodine atoms were found to be liberated in less than 4 ps. The structure, absolute fraction, and electronic state of the radical were determined. The CF 2 radical was found to be in X1A1 ground state with C-F and F⋯F distances of 1.30(±0.02) Å and 2.06(±0.06) Å, respectively.

  16. 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.

  17. 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.

  18. 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

  19. High-resolution real-time imaging processor for airborne SAR

    NASA Astrophysics Data System (ADS)

    Yu, Weidong; Wu, Shumei

    2003-04-01

    Real-time imaging processor can provide Synthetic Aperture Radar (SAR) image in real-time mode, which is necessary for airborne SAR applications such as real-time monitoring and battle reconnaissance. This paper describes the development of high-resolution real-time imaging processor in Institute of Electronic, Chinese Academy of Sciences (IECAS). The processor uses parallel multiple channels to implement large-volume calculation needed for SAR real-time imaging. A sub-aperture method is utilized to divide azimuth Doppler spectrum into two parts, which correspond two looks. With sub-aperture method, high processing efficiency, less range migration effect and reduced memory volume can be achieved. The imaging swath is also divided into two segments, which are processed in a parallel way. Range-Doppler algorithm, which consists of range migration correction and azimuth compression, is implemented in the processor. Elaborate software programming ensures a high efficient utilization of hardware. Experimental simulation and field flight indicate this system is successful. The principles, architecture, hardware implementation of the processor are presented in this paper in details.

  20. 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.

  1. 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

  2. Effect of carrier fluid viscosity on retention time and resolution in gravitational field-flow fractionation.

    PubMed

    Lee, Seungho; Kang, Da Young; Park, Miri; Williams, P Stephen

    2011-05-01

    Gravitational field-flow fractionation (GrFFF) is a useful technique for fast separation of micrometer-sized particles. Different sized particles are carried at different velocities by a flow of fluid along an unobstructed thin channel, resulting in a size-based separation. They are confined to thin focused layers in the channel thickness where force due to gravity is exactly opposed by hydrodynamic lift forces (HLF). It has been reported that the HLF are a function of various parameters including the flow rate (or shear rate), the size of the particles, and the density and viscosity of the liquid. The dependence of HLF on these parameters offers a means of altering the equilibrium transverse positions of the particles in GrFFF, and hence their elution times. In this study, the effect of the viscosity of the carrier fluid on the elution behavior (retention, zone broadening, and resolution) of micrometer-sized particles in GrFFF was investigated using polystyrene (PS) latex beads as model particles. In order to change the carrier liquid viscosity without affecting its density, various amounts of (hydroxypropyl) methyl cellulose (HPMC) were added to the aqueous carrier liquid. It was found that particles migrate at faster rates as the carrier viscosity is increased, which confirms the dependence of HLF on viscosity. At the same time, particle size selectivity decreased but peak shape and symmetry for the more strongly retained particles improved. As a result, separation was improved in terms of both the separation time and resolution with increase of carrier viscosity. A theoretical model for plate height in GrFFF is also presented, and its predictions are compared to experimentally measured values.

  3. A high-resolution mini-microscope system for wireless real-time monitoring.

    PubMed

    Wang, Zongjie; Boddeda, Akash; Parker, Benjamin; Samanipour, Roya; Ghosh, Sanjoy; Menard, Frederic; Kim, Keekyoung

    2017-09-04

    Compact, cost-effective and high-performance microscope that enables the real-time imaging of cells and lab-on-a-chip devices is highly demanded for cell biology and biomedical engineering. This paper aims to present the design and application of an inexpensive wireless mini-microscope with resolution up to 2592 × 1944 pixels and speed up to 90 fps. The mini-microscope system was built on a commercial embedded system (Raspberry Pi). We modified a camera module and adopted an inverse dual lens system to obtain the clear field of view and appropriate magnification for tens of micrometer objects. The system was capable of capturing time-lapse images and transferring image data wirelessly. The entire system can be operated wirelessly and cordlessly in a conventional cell culturing incubator. The developed mini-microscope was used to monitor the attachment and proliferation of NIH-3T3 and HEK 293 cells inside an incubator for 50 hours. In addition, the mini-microscope was used to monitor a droplet generation process in a microfluidic device. The high-quality images captured by the mini-microscope enabled us an automated analysis of experimental parameters. The successful applications prove the great potential of the developed mini-microscope for monitoring various biological samples and microfluidic devices. This paper presents the design of a high resolution mini-microscope system that enables the wireless real-time imaging of cells inside the incubator. This system has been verified to be a useful tool to obtain high-quality images and videos for the automated quantitative analysis of biological samples and lab-on-a-chip devices in the long term.

  4. The Assessment of Grid Resolution for Real-time Flood Warning in Urban area

    NASA Astrophysics Data System (ADS)

    Hsu, M. H.; Huang, C. J.; Teng, W. H.; Huang, C. Y.

    2016-12-01

    According to the unique natural environment, Taiwan confronts a severe flood damage problem in typhoon seasons. Recently, due to global climate change and extreme weather, the prediction and prevention of flood damage becomes one of the most important research issues. The highly development area and densely concentrated population result in severe damage during flood occurs. Flood management and response plan become more important in metropolitan area. For the past two decades, the hydrological monitory and rainfall intense prediction techniques have a great progress in its accuracy. QPESUMS (Quantitative Precipitation Estimation and Segregation Using Multiple Sensors) developed by the Central Weather Bureau was applied to observe real-time Radar rainfall and its spatial distribution. DTM (Digital Terrain Model) and 2D inundation model which considers the blockage effect of buildings were applied to simulate the water depth in metropolitan area. In this study, Kaohsiung city is selected as the study area and typhoon Fanapi which makes tremendous flood damage in Southern Taiwan in 2010 is adopted as the study case. The main purpose of this study is to find the proper grid resolution of flood forecasting computations in Kaohsiung city from the evaluations of the efficiency and accuracy of three different resolutions.

  5. High time-resolution electron energy and flux estimates inside regions of flickering and pulsating aurora

    NASA Astrophysics Data System (ADS)

    Michell, R.; Samara, M.; Grubbs, G. A., II

    2016-12-01

    The temporal fluctuations within the aurora can vary over vastly different timescales, indicating different generation mechanisms. Fluctuating aurora best describes two main types of aurora, commonly referred to as flickering aurora and pulsating aurora. These two types of aurora contain temporal fluctuations that vary from being periodic to semi-periodic to nearly random and covering timescales of 20 Hz to minutes. High-resolution multi-spectral auroral imaging is used to compute emission line ratios that can be used in combination with electron transport modeling in order to estimate the average energy and total energy flux of the precipitating electrons. The auroral imaging used here was recorded at a rate of 40 frames per second, with energy and flux estimates made at each frame, enabling unprecedented time resolution for examining the precipitating electron characteristics within these fluctuations. The variations in the total energy flux and average energy of the precipitating electrons will be compared to the phase of the optical auroral cycle, in order to gain insight into the generation processes creating the fluctuating cycles. The emphasis of this talk will be on using these techniques to gain insight into the outstanding questions.

  6. 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.

  7. On the rms errors and dynamic ranges of triple- and quadruple-pulse particle tracking velocimetry (PTV)

    NASA Astrophysics Data System (ADS)

    Ding, Liuyang; Adrian, Ronald; Gogineni, Sivaram

    2016-11-01

    Multi-pulse PTV extends conventional dual-pulse PTV by fitting a polynomial to particle locations measured from three or four pulses in a burst, aiming at more accurately resolving a particle short-period trajectory. Particle velocity and acceleration are then evaluated at an optimal time minimizing rms errors. Numerical simulations were performed to completely study the behaviors of position, velocity, and acceleration rms errors of triple- and quadruple-pulse PTV in a 4-D space spanned by four dimensionless variables - normalized time, normalized displacement, normalized particle locating noise, and acceleration factor. We compared three analysis methods - 3-pulse with quadratic fitting, 4-pulse with cubic fitting and 4-pulse with quadratic least-square fitting. In addition, generalized definitions of dynamic spatial range (DSR) and dynamic velocity range (DVR) are proposed for multi-pulse analyses. We calculated DSR ratios and DVR ratios between the multi-pulse and 2-pulse under various flow conditions and noise levels. It is found that the DSR and DVR could be improved by up to 100 times and 10 times, respectively, when the particle trajectory is strongly curved, deceleration is pronounced, and particle locations are accurately determined. This work is supported by ONR N00014-14-C-0095.

  8. 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.

  9. REAL-TIME high-resolution urban surface water flood mapping to support flood emergency management

    NASA Astrophysics Data System (ADS)

    Guan, M.; Yu, D.; Wilby, R.

    2016-12-01

    Strong evidence has shown that urban flood risks will substantially increase because of urbanisation, economic growth, and more frequent weather extremes. To effectively manage these risks require not only traditional grey engineering solutions, but also a green management solution. Surface water flood risk maps based on return period are useful for planning purposes, but are limited for application in flood emergencies, because of the spatiotemporal heterogeneity of rainfall and complex urban topography. Therefore, a REAL-TIME urban surface water mapping system is highly beneficial to increasing urban resilience to surface water flooding. This study integrated numerical weather forecast and high-resolution urban surface water modelling into a real-time multi-level surface water mapping system for Leicester City in the UK. For rainfall forecast, the 1km composite rain radar from the Met Office was used, and we used the advanced rainfall-runoff model - FloodMap to predict urban surface water at both city-level (10m-20m) and street-level (2m-5m). The system is capable of projecting 3-hour urban surface water flood, driven by rainfall derived from UK Met Office radar. Moreover, this system includes real-time accessibility mapping to assist the decision-making of emergency responders. This will allow accessibility (e.g. time to travel) from individual emergency service stations (e.g. Fire & Rescue; Ambulance) to vulnerable places to be evaluated. The mapping results will support contingency planning by emergency responders ahead of potential flood events.

  10. 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.

  11. Controlling the freezing process: a robotic device for rapidly freezing biological tissues with millisecond time resolution.

    PubMed

    Tikunov, Boris A; Rome, Lawrence C

    2007-10-01

    A robotic cryogenic device was developed which allows freezing of thick biological tissues with millisecond time resolution. The device consists of two horizontally oriented hammers (pre-cooled with liquid N(2)) driven by two linear servo-motors. The tissue sample is bathed in Ringers contained in a chamber which drops rapidly out of the way just as the hammers approach. A third linear motor is vertically oriented, and permits the rapidly dropping chamber to smoothly decelerate. All movements were performed by the three motors and four solenoids controlled by a PC. Mechanical adjustments, that change the size of the gap between the hammers at the end position, permit the final thickness of the frozen tissue to be varied. Here we show that the freezing time increased with the square of the final thickness of the frozen bundle. However, when bundles of different original thicknesses (up to at least 1mm) were compressed to the same final thickness (e.g., 0.2mm), they exhibited nearly equal freezing times. Hence, by being able to adjust the final thickness of the frozen bundles, the device not only speeds the rate of freezing, but standardizes the freezing time for different diameter samples. This permits the use of freezing for accurate determination of the kinetics of cellular processes in biological tissue.

  12. 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

  13. Generation of future high-resolution rainfall time series with a disaggregation model

    NASA Astrophysics Data System (ADS)

    Müller, Hannes; Haberlandt, Uwe

    2017-04-01

    High-resolution rainfall data are needed in many fields of hydrology and water resources management. For analyzes of future rainfall condition climate scenarios exist with hourly values of rainfall. However, the direct usage of these data is associated with uncertainties which can be indicated by comparisons of observations and C20 control runs. An alternative is the derivation of changes of rainfall behavior over the time from climate simulations. Conclusions about future rainfall conditions can be drawn by adding these changes to observed time series. A multiplicative cascade model is used in this investigation for the disaggregation of daily rainfall amounts to hourly values. Model parameters can be estimated by REMO rainfall time series (UBA-, BfG- and ENS-realization), based on ECHAM5. Parameter estimation is carried out for C20 period as well as near term and long term future (2021-2050 and 2071-2100). Change factors for both future periods are derived by parameter comparisons and added to the parameters estimated from observed time series. This enables the generation of hourly rainfall time series from observed daily values with respect to future changes. The investigation is carried out for rain gauges in Lower Saxony. Generated Time series are analyzed regarding statistical characteristics, e.g. extreme values, event-based (wet spell duration and amounts, dry spell duration, …) and continuum characteristics (average intensity, fraction of dry intervals,…). The generation of the time series is validated by comparing the changes in the statistical characteristics from the REMO data and from the disaggregated data.

  14. A time resolution study with a plastic scintillator read out by a Geiger-mode Avalanche Photodiode

    NASA Astrophysics Data System (ADS)

    Stoykov, A.; Scheuermann, R.; Sedlak, K.

    2012-12-01

    In this work we attempt to establish the best time resolution attainable with a scintillation counter consisting of a plastic scintillator read out by a Geiger-mode Avalanche Photodiode. The measured time resolution is inversely proportional to the square root of the energy deposited in the scintillator, and scales to σ=18 ps at 1 MeV. This result competes with the best ones reported for photomultiplier tubes.

  15. Coherence conversion for optimized resolution in optical measurements - example of femtosecond time resolution using the transverse coherence of 100-picosecond X-rays

    NASA Astrophysics Data System (ADS)

    Adams, Bernhard W.

    2015-07-01

    A way is proposed to obtain a femtosecond time resolution over a picosecond range in laser-pump, X-ray probe spectroscopic measurements where the light source and the detector are much slower than that. It is based on a phase-space transformation from the time/bandwidth to the spatial/wavenumber domain to match the coherence properties of synchrotron radiation to the requirements of femtosecond experiments. In a first step, the geometry of the laser incidence maps time, t, of laser-induced femtosecond dynamics to a spatial coordinate, x. Then, a far-field X-ray diffraction pattern, i.e. the optical Fourier transform, is obtained from the laser-induced modifications of the sample properties, including shifts of X-ray absorption edges and changes in crystallographic unit-cell form factors. Whereas the first step is similar to previously used schemes for femtosecond time resolution, the second one is substantially different with specific advantages discussed in the text. Key to this technique is that the modulus of the Fourier transform is invariant with respect to translations ? along x, which are due to the ? correlation. It can, therefore, be acquired in a simple intensity measurement with a slow detector. The phase, which does vary strongly with ?, is missing in the intensity data, but can be recovered through a heterodyning technique. 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.

  16. Reference materials (RMs) for analysis of the human factor II (prothrombin) gene G20210A mutation.

    PubMed

    Klein, Christoph L; Márki-Zay, János; Corbisier, Philippe; Gancberg, David; Cooper, Susan; Gemmati, Donato; Halbmayer, Walter-Michael; Kitchen, Steve; Melegh, Béla; Neumaier, Michael; Oldenburg, Johannes; Leibundgut, Elisabeth Oppliger; Reitsma, Pieter H; Rieger, Sandra; Schimmel, Heinz G; Spannagl, Michael; Tordai, Attilia; Tosetto, Alberto; Visvikis, Sophie; Zadro, Renata; Mannhalter, Christine

    2005-01-01

    The Scientific Committee of Molecular Biology Techniques (C-MBT) in Clinical Chemistry of the IFCC has initiated a joint project in co-operation with the European Commission, Joint Research Centre, Institute of Reference Materials and Measurements to develop and produce plasmid-type reference materials (RMs) for the analysis of the human prothrombin gene G20210A mutation. Although DNA tests have a high impact on clinical decision-making and the number of tests performed in diagnostic laboratories is high, issues of quality and quality assurance exist, and currently only a few RMs for clinical genetic testing are available. A gene fragment chosen was produced that spans all primer annealing sites published to date. Both the wild-type and mutant alleles of this gene fragment were cloned into a pUC18 plasmid and two plasmid RMs were produced. In addition, a mixture of both plasmids was produced to mimic the heterozygous genotype. The present study describes the performance of these reference materials in a commutability study, in which they were tested by nine different methods in 13 expert laboratories. This series of plasmid RMs are, to the best of our knowledge, the first plasmid-type clinical genetic RMs introduced worldwide.

  17. 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.

  18. Accurate Estimation of the RMS Emittance from Single Current Amplifier Data

    NASA Astrophysics Data System (ADS)

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

    2002-11-01

    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- ion source.

  19. Raman-assisted Brillouin optical time-domain analysis with sub-meter resolution over 100 km.

    PubMed

    Angulo-Vinuesa, X; Martin-Lopez, S; Corredera, P; Gonzalez-Herraez, M

    2012-05-21

    Sub-meter resolution in long-distance Brillouin Optical Time Domain Analysis (BOTDA) cannot be trivially achieved due to several issues including: resolution-uncertainty trade-offs, self-phase modulation, fiber attenuation, depletion, etc. In this paper we show that combining Raman assistance, differential pulse-width pair (DPP) measurements and a novel numerical de-noising procedure, we could obtain sub-meter resolution Brillouin optical time-domain analysis over a range of 100 km. We successfully demonstrate the detection of a 0.5 meter hot-spot in the position of worst contrast along the fiber.

  20. Analysis of High Time Resolution Optical Spectra of RX J0558.0+5353

    NASA Astrophysics Data System (ADS)

    Walker, K. A.; Garnavich, P. M.; Noriega-Crespo, A.

    1996-12-01

    We analyze high time resolution optical spectra of the DQ Her type intermediate polar RX J0558.0+5353 obtained at the MMT in December 1995. The spectra cover nearly a complete orbit and reveal a pulse in the mean flux of the continua and in the fluxes of the Hβ , Hγ and He II 4686 lines. This pulse, with a fundamental frequency of approximately 165c/d and a first harmonic at 316c/d confirms the spin period reported by Skillman (1995). Measurements of radial velocities in the line wings suggest that the HeII emission arises from an inner region of the accretion disk, closer to the white dwarf than the region where the Balmer lines are emitted. Doppler tomography of Hβ and HeII lines yields visual confirmation of this picture of accretion and emissions in this intermediate polar system.

  1. Near-infrared high-resolution real-time omnidirectional imaging platform for drone detection

    NASA Astrophysics Data System (ADS)

    Popovic, Vladan; Ott, Beat; Wellig, Peter; Leblebici, Yusuf

    2016-10-01

    Recent technological advancements in hardware systems have made higher quality cameras. State of the art panoramic systems use them to produce videos with a resolution of 9000 x 2400 pixels at a rate of 30 frames per second (fps).1 Many modern applications use object tracking to determine the speed and the path taken by each object moving through a scene. The detection requires detailed pixel analysis between two frames. In fields like surveillance systems or crowd analysis, this must be achieved in real time.2 In this paper, we focus on the system-level design of multi-camera sensor acquiring near-infrared (NIR) spectrum and its ability to detect mini-UAVs in a representative rural Swiss environment. The presented results show the UAV detection from the trial that we conducted during a field trial in August 2015.

  2. A design for a high resolution very-low-Q time-of flight diffractometer.

    SciTech Connect

    Hjelm, R. P.

    1998-09-29

    The design of a high resolution view low-Q time of flight diffractometer was motivated by the anticipated need to perform small-angle neutron scattering measurements at far lower momentum transfer and higher precision than currently available at either pulsed or steady state sources. In addition, it was recognized that flexibility in the configuration of the instrument and ease in which data is acquired are important. The design offers two configurations, a high intensity/very low Q geometry employing a focusing mirror and a medium to high Q-precision/low Q configuration using standard pinhole collimation geometry. The quality of the mirror optics is very important to the performance of the high intensity/very low Q configuration. We believe that the necessary technology exists to fabricate the high quality mirror optics required for the instrument.

  3. Super-resolution spectral estimation in short-time non-contact vital sign measurement

    NASA Astrophysics Data System (ADS)

    Sun, Li; Li, Yusheng; Hong, Hong; Xi, Feng; Cai, Weidong; Zhu, Xiaohua

    2015-04-01

    Non-contact techniques for measuring vital signs attract great interest due to the benefits shown in medical monitoring, military application, etc. However, the presence of respiration harmonics caused by nonlinear phase modulation will result in performance degradation. Suffering from smearing and leakage problems, conventional discrete Fourier transform (DFT) based methods cannot distinguish the heartbeat component from closely located respiration harmonics in frequency domain, especially in short-time processing. In this paper, the theory of sparse reconstruction is merged with an extended harmonic model of vital signals, aiming at achieving a super-resolution spectral estimation of vital signals by additionally exploiting the inherent sparse prior information. Both simulated and experimental results show that the proposed algorithm has superior performance to DFT-based methods and the recently applied multiple signal classification algorithm, and the required processing window length has been shortened to 5.12 s.

  4. The High Time Resolution Universe Pulsar Survey - II. Discovery of five millisecond pulsars

    NASA Astrophysics Data System (ADS)

    Bates, S. D.; Bailes, M.; Bhat, N. D. R.; Burgay, M.; Burke-Spolaor, S.; D'Amico, N.; Jameson, A.; Johnston, S.; Keith, M. J.; Kramer, M.; Levin, L.; Lyne, A.; Milia, S.; Possenti, A.; Stappers, B.; van Straten, W.

    2011-10-01

    We present the discovery of five millisecond pulsars found in the mid-Galactic latitude portion of the High Time Resolution Universe (HTRU) survey. The pulsars have rotational periods from ˜2.3 ms to ˜7.5 ms, and all are in binary systems with orbital periods ranging from ˜0.3 to ˜150 d. In four of these systems, the most likely companion is a white dwarf, with minimum masses of ˜0.2 M⊙. The other pulsar, J1731-1847, has a very low mass companion and exhibits eclipses and is thus a member of the 'black widow' class of pulsar binaries. These eclipses have been observed in bands centred near frequencies of 700, 1400 and 3000 MHz, from which measurements have been made of the electron density in the eclipse region. These measurements have been used to examine some possible eclipse mechanisms. The eclipse and other properties of this source are used to perform a comparison with the other known eclipsing and 'black widow' pulsars. These new discoveries occupy a short-period and high-dispersion measure (DM) region of parameter space, which we demonstrate is a direct consequence of the high time and frequency resolution of the HTRU survey. The large implied distances to our new discoveries make observation of their companions unlikely with both current optical telescopes and the Fermi Gamma-ray Space Telescope. The extremely circular orbits make any advance of periastron measurements highly unlikely. No relativistic Shapiro delays are obvious in any of the systems although the low flux densities would make their detection difficult unless the orbits were fortuitously edge-on.

  5. High-Resolution Gravity and Time-Varying Gravity Field Recovery using GRACE and CHAMP

    NASA Technical Reports Server (NTRS)

    Shum, C. K.

    2002-01-01

    This progress report summarizes the research work conducted under NASA's Solid Earth and Natural Hazards Program 1998 (SENH98) entitled High Resolution Gravity and Time Varying Gravity Field Recovery Using GRACE (Gravity Recovery and Climate Experiment) and CHAMP (Challenging Mini-satellite Package for Geophysical Research and Applications), which included a no-cost extension time period. The investigation has conducted pilot studies to use the simulated GRACE and CHAMP data and other in situ and space geodetic observable, satellite altimeter data, and ocean mass variation data to study the dynamic processes of the Earth which affect climate change. Results from this investigation include: (1) a new method to use the energy approach for expressing gravity mission data as in situ measurements with the possibility to enhance the spatial resolution of the gravity signal; (2) the method was tested using CHAMP and validated with the development of a mean gravity field model using CHAMP data, (3) elaborate simulation to quantify errors of tides and atmosphere and to recover hydrological and oceanic signals using GRACE, results show that there are significant aliasing effect and errors being amplified in the GRACE resonant geopotential and it is not trivial to remove these errors, and (4) quantification of oceanic and ice sheet mass changes in a geophysical constraint study to assess their contributions to global sea level change, while the results improved significant over the use of previous studies using only the SLR (Satellite Laser Ranging)-determined zonal gravity change data, the constraint could be further improved with additional information on mantle rheology, PGR (Post-Glacial Rebound) and ice loading history. A list of relevant presentations and publications is attached, along with a summary of the SENH investigation generated in 2000.

  6. 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

  7. Analytical calculation of the lower bound on timing resolution for PET scintillation detectors comprising high-aspect-ratio crystal elements

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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%.

  8. 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.

  9. Realizing PET systems with 100 ps FWHM coincidence timing resolution (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Cates, Joshua; Levin, Craig

    2016-10-01

    The past two decades have seen much progress in coincidence timing resolution (CTR) for time-of-flight (TOF) capable positron emission tomography (PET) systems. With these advancements, clinical TOF-PET systems have achieved sub-400 ps FWHM (full-width-at-half-maximum) CTR, providing decreased patient radiation dose, shorter scan time, improved lesion detectability, increased accuracy and precision of lesion uptake measurements, and less sensitivity to errors in data correction techniques (normalization, scatter, and attenuation corrections). An important and long-standing milestone for the TOF-PET community is 100 ps FWHM CTR. At that level of timing performance, more than a factor of five improvement in image signal-to-noise ratio is possible compared to non-TOF-PET, with the potential for a transformational impact on quantitative PET imaging. With advancements in silicon photomultiplier technologies, novel scintillation materials and signal processing techniques, sub-100 ps CTR has been reported for relatively short scintillation crystal elements (3 mm length). However, clinical PET requires scintillation crystal elements that are 20 mm length or greater to provide adequate stopping power for 511 keV photons. This increased crystal length reduces the light collection efficiency and increases the scintillation photon transit time variance, resulting in degraded CTR. Significant strides have been made in achieving sub-150 ps FWHM CTR with 20 mm length crystals in single pixel, bench top experiments. We will present perspectives on the entire detection chain, from luminescence to signal processing and time-pickoff to enable 100 ps CTR at the level of full clinically-relevant detector modules.

  10. Extraterrestrial influence on Radon - statistical criteria in long and high resolution time series

    NASA Astrophysics Data System (ADS)

    Steinitz, Gideon; Piatibratova, Oksana; Kotlarsky, Peter

    2017-04-01

    Extraterrestrial influence on radon in air, in subsurface and above surface situations, were first proposed based on geological observations, and following this on results from simulation experiments using the Enhanced Confined Mode (ECM) configuration. The proposition is based on statistical features of the periodic components of variation of radon - in the diurnal (24-hour), solar ( 30 days) and annual (365 days) periodicity bands. Experience gained from gamma and alpha time series of radon indicates the following criteria: a. Occurrence of a large annual variation and an associated semi-annual periodicity. b. Summer peak time (SPT) of the annual variation which is different for alpha and gamma radiation, and also different from that of atmospheric parameters (P, T). c. Annual co-modulation of amplitude and phase of the diurnal constituents S1, S2 and S3. d. Occurrence of Solar Rotation (SR) periodicity, with a wavelength around 30 days, which is related to the rotation of Sun around its axis. Imperative is that SR is independent of the rotational relations of the Earth-Sun system. Thus, this is an independent indication of an extraterrestrial influence. e. Using the 24-hour time window as reference for demonstrating long term patterns of variation - of: 1) in the time domain: average count rate; 2) in the frequency domain. f. Observation of side bands at diurnal constituents S1 and S2 due to non-linear interaction between annual and diurnal periodicities in radon. g. Directionality, associated to global orientation. These statistical features are observed in long time series obtained at a time resolution of 15-minutes. Interpreting these as due to an extraterrestrial influence is in accordance and in addition to the frequently observed disparity between radon phenomena and local atmospheric influences, both at geologic situations as well as in ECM simulations. Verification of these findings, among other by interaction with nuclear physicists, has important

  11. 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.

  12. 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."

  13. High-Time Resolution Measurements of Heavy Ions with SOHO/CELIAS/CTOF

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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 H+, which we refer to as heavy ions. This is achieved by the combined measurement of the energy-per-charge, the time-of-flight and the energy of the incident ions. The CTOF instrument combines a remarkable time-of-flight resolution with a large effective area which allows to determine the velocity distributions of a wide range of heavy ions with 5 minute cadence. Based on a sophisticated in-flight calibration and count rate analysis we derived 5-minute velocity distributions for typical charge states of solar wind carbon, oxygen, silicon and iron for the CTOF measurement period between day of year 150 and 220 in 1996. In contrast to previous studies we used pure Pulse Height Analysis (PHA) data, which yields the full mass and mass-per-charge and velocity information. We analyzed the velocity spectra for differential streaming relative to the solar wind bulk proton speed, measured simultaneously with the CELIAS Proton Monitor (PM). Here we present our results which should provide experimental constraints for theories of resonant wave-particle interaction and preferential acceleration of heavy ions in the solar wind.

  14. Effects of satellite data resolution on measuring the space/time variations of surfaces and clouds

    NASA Technical Reports Server (NTRS)

    Seze, Genevieve; Rossow, William B.

    1991-01-01

    The correlated distributions of satellite-measured visible and infrared radiances, caused by spatial and temporal variations in clouds and surfaces, have been found to be characteristic of the major climate regimes and can be described by the attributes of bidimensional and monodimensional histograms and time-composite images. Most of the variability of both the surfaces and clouds is found to occur at scales larger than the minimum resolved by satellite imagery. Since satellite imaging data sets are difficult to analyze because of their large volumes, many studies reduce the volume by various sampling or averaging schemes. The effects of data resolution and sampling on the radiance histogram statistics and on the time-composite image characteristics are examined. In particular, the sampling strategy used by the International Satellite Cloud Climatology Project is tested. This sampling strategy is found to preserve the statistics of smaller cloud variations for most regions, with the exception of very rare events, if they are accumulated over large enough areas (at least 500 km in dimension) and long enough time periods (at least one month).

  15. Real time observation of mouse fetal skeleton using a high resolution X-ray synchrotron

    PubMed Central

    Chang, Dong Woo; Kim, Bora; Shin, Jae Hoon; Yun, Young Min; Je, Jung Ho; Hwu, Yeu kuang; Yoon, Jung Hee

    2011-01-01

    The X-ray synchrotron is quite different from conventional radiation sources. This technique may expand the capabilities of conventional radiology and be applied in novel manners for special cases. To evaluate the usefulness of X-ray synchrotron radiation systems for real time observations, mouse fetal skeleton development was monitored with a high resolution X-ray synchrotron. A non-monochromatized X-ray synchrotron (white beam, 5C1 beamline) was employed to observe the skeleton of mice under anesthesia at embryonic day (E)12, E14, E15, and E18. At the same time, conventional radiography and mammography were used to compare with X-ray synchrotron. After synchrotron radiation, each mouse was sacrificed and stained with Alizarin red S and Alcian blue to observe bony structures. Synchrotron radiation enabled us to view the mouse fetal skeleton beginning at gestation. Synchrotron radiation systems facilitate real time observations of the fetal skeleton with greater accuracy and magnification compared to mammography and conventional radiography. Our results show that X-ray synchrotron systems can be used to observe the fine structures of internal organs at high magnification. PMID:21586868

  16. 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.

  17. 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.

  18. Very-high-resolution time-lapse photography for plant and ecosystems research.

    PubMed

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

    2013-09-01

    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. • 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). • 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.

  19. High-Resolution Time Profiles of Fiber Bursts at 1420 and 2695 MHz

    NASA Astrophysics Data System (ADS)

    Zlobec, P.; Karlický, M.

    2014-05-01

    To obtain constraints for models of fiber bursts, high-resolution time (0.01 s) profiles of the fiber bursts recorded at 1420 and 2695 MHz by the Trieste radiometers are studied in detail. The fiber bursts were identified using Ondřejov radio spectra. During the years 2000 - 2005, 18 intervals with fiber bursts were selected; 26 groups were defined and about 700 fibers were analyzed in detail. More than 300 pulsations, present almost simultaneously with the fibers, were also selected and studied in order to find similarities or differences between these two types of fine structures. It was found that the polarization of the associated continuum, both for fiber bursts and pulsations, is practically the same. Evaluating the ratio between absorption over emission of many single fibers we found that this parameter is very different even for nearby bursts; however, we realized that this ratio shows a tendency to decrease with time. Finally, the time profile of one selected fiber burst was fitted using a recent model based on the modulation of the broadband radio emission by fast magnetoacoustic waves. The results are discussed.

  20. 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

  1. 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.

  2. Effects of satellite data resolution on measuring the space/time variations of surfaces and clouds

    NASA Technical Reports Server (NTRS)

    Seze, Genevieve; Rossow, William B.

    1991-01-01

    The correlated distributions of satellite-measured visible and infrared radiances, caused by spatial and temporal variations in clouds and surfaces, have been found to be characteristic of the major climate regimes and can be described by the attributes of bidimensional and monodimensional histograms and time-composite images. Most of the variability of both the surfaces and clouds is found to occur at scales larger than the minimum resolved by satellite imagery. Since satellite imaging data sets are difficult to analyze because of their large volumes, many studies reduce the volume by various sampling or averaging schemes. The effects of data resolution and sampling on the radiance histogram statistics and on the time-composite image characteristics are examined. In particular, the sampling strategy used by the International Satellite Cloud Climatology Project is tested. This sampling strategy is found to preserve the statistics of smaller cloud variations for most regions, with the exception of very rare events, if they are accumulated over large enough areas (at least 500 km in dimension) and long enough time periods (at least one month).

  3. A GEANT4 study on the time resolution of a fast plastic scintillator read out by a G-APD

    NASA Astrophysics Data System (ADS)

    Sedlak, K.; Stoykov, A.; Scheuermann, R.

    2012-12-01

    The time resolution of a fast scintillation counter, consisting of a plastic scintillator read out by a Geiger-mode Avalanche Photodiode, is studied over a wide range of the number of detected photons (primary photoelectrons) using the GEANT4 simulation toolkit. Different timing definitions such as first photon detection, leading edge and constant fraction discrimination are considered. In the latter case the predictions are compared with the existing experimental data. We also show that due to the finite scintillation rise time, finite scintillator dimensions and also due to the finite single photon time resolution in G-APD cells, the time resolution for the first detected photon in real detectors substantially deviates from the σ˜1/Nphe dependence, theoretically predicted for a scintillator with zero rise time.

  4. 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.

  5. 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.

  6. 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.

  7. Relation between field energy and RMS emittance in intense particle beams

    SciTech Connect

    Wangler, T.P.; Crandall, K.R.; Mills, R.S.; Reiser, M.

    1985-01-01

    An equation is presented for continuous beams with azimuthal symmetry and continuous linear focusing, which expresses a relationship between the rate of change for squared rms emittance and the rate of change for a quantity we call the nonlinear field energy. The nonlinear field energy depends on the shape of the charge distribution and corresponds to the residual field energy possessed by beams with nonuniform charge distributions. The equation can be integrated for the case of an rms matched beam to yield a formula for space-charge-induced emittance growth that we have tested numerically for a variety of initial distributions. The results provide a framework for discussing the scaling of rms emittance growth and an explanation for the well-established lower limit on output emittance. 15 refs., 4 figs.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. Constant RMS versus constant peak modulation for the perceptual equivalence of sinusoidal amplitude modulated signals.

    PubMed

    Regele, Oliver B; Koivuniemi, Andrew S; Otto, Kevin J

    2013-01-01

    Neuroprosthetics using intracortical microstimulation can potentially alleviate sensory deprivation due to injury or disease. However the information bandwidth of a single microstimulation channel remains largely unanswered. This paper presents three experiments that examine the importance of Peak Power/Charge and RMS Power/Charge for detection of acoustic and electrical Sinusoidal Amplitude Modulated stimuli by the auditory system. While the peripheral auditory system is sensitive to RMS power cues for the detection of acoustic stimuli, here we provide results that suggest that the auditory cortex is sensitive to peak charge cues for electrical stimuli. Varying the modulation frequency and depth do not change this effect for detection of modulated electrical stimuli.

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

    NASA Image and Video Library

    1990-04-24

    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).

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

    NASA Image and Video Library

    1991-04-07

    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.

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

    NASA Image and Video Library

    1993-06-25

    STS057-31-030 (25 June 1993) --- Astronaut Nancy J. Sherlock operates Endeavour's remote manipulator system (RMS) during the June 25 extravehicular activity of two crewmates. At one point, astronaut G. David Low, while his feet were anchored to a special restraint device on the end of the RMS arm, moved about, with Sherlock's aid, while holding astronaut Peter J. K. (Jeff) Wisoff. The activity represented an evaluation of techniques which might be used on planned future missions -- a 1993 servicing visit to the Hubble Space Telescope and later space station work -- which will require astronauts to frequently lift objects of similar sized bulk.

  17. 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.

  18. Test-beam results of a silicon pixel detector with Time-over-Threshold read-out having ultra-precise time resolution

    NASA Astrophysics Data System (ADS)

    Aglieri Rinella, G.; Cortina Gil, E.; Fiorini, M.; Kaplon, J.; Kluge, A.; Marchetto, F.; Albarran, M. E. Martin; Morel, M.; Noy, M.; Perktold, L.; Tiuraniem, S.; Velghe, B.

    2015-12-01

    A time-tagging hybrid silicon pixel detector developed for beam tracking in the NA62 experiment has been tested in a dedicated test-beam at CERN with 10 GeV/c hadrons. Measurements include time resolution, detection efficiency and charge sharing between pixels, as well as effects due to bias voltage variations. A time resolution of less than 150 ps has been measured with a 200 μm thick silicon sensor, using an on-pixel amplifier-discriminator and an end-of-column DLL-based time-to-digital converter.

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

    PubMed

    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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. High space-time resolution analysis of ice motion at a rapidly retreating tidewater glacier (Invited)

    NASA Astrophysics Data System (ADS)

    Oneel, S.; Joughin, I. R.; March, R. S.; Burgess, E. W.; Welty, E.; Pfeffer, W. T.; Larsen, C. F.

    2013-12-01

    Rapid changes to rates of sea level rise are forced in large part by tidewater glacier dynamics. Alaska's Columbia Glacier is an iconic example; in recent years, calving losses account for roughly 20% of the net mass loss from the entire Alaska region. In turn, the Alaska region accounts for ~20% of global new-water sea-level rise. To better understand the mechanics of rapid tidewater glacier mass loss, we present and analyze surface elevation and velocity data acquired at high time resolution since fall 2011. Strong seasonality in flow speed exists, with more than a doubling of near-terminus speed occurring between summer and winter. The imagery provides unprecedented spatial coverage, demonstrating spatial coherence in flow variability across most, but not all, tributaries. Preliminary calculations of ice flux also show strong seasonality, with variable year-to-year timing of peak discharge. Compared to previous estimates, the average flux in this most recent interval is reduced by ~30-40%. An additional overdeepening is located upstream from the present-day terminus, indicating another episode of increased flux is possible. However, total glacier volume has been reduced by ~50% during the retreat, and peak discharge from Columbia has likely already occurred. Our analysis suggests that, as the Columbia Glacier retreat comes to a conclusion, rates of mass loss from the Alaska region will decrease in the near-future, unless another tidewater glacier enters rapid retreat.

  6. Directional view method for a time-sequential autostereoscopic display with full resolution.

    PubMed

    Zhuang, Zhenfeng; Zhang, Lei; Surman, Phil; Guo, Song; Cao, Bin; Zheng, Yuanjin; Sun, Xiao Wei

    2016-10-01

    A time-sequential autostereoscopic three-dimensional (3D) display using a set of cylindrical optical elements (COEs) as the backlight steering is proposed. The operation principle of the system and its detailed design are described. In our system, the COEs control the direction of the backlight for the proposed system of the user's right and left views. Additionally, the displayed images can be observed under ambient lighting by implementing the high density light-emitting diode (LED) arrays. Compared to the first-generation array display, the image resolution is greatly improved by the addition of the time multiplexing technique. A prototype system using a set of COEs, LED arrays, two linear Fresnel lenses, and an elliptical diffuser is constructed. Here, the directional backlight beams are synchronized with the right and left images alternately displayed on the liquid crystal display (LCD) screen, and two convergent viewing zones are formed alternately in front of the user's eyes; then 3D images are perceived because of persistence of the vision of human eye. The experimental results show that the proposed method is a potential technology for 3D applications such as 3D television.

  7. 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.

  8. Ultrasound array transmitter architecture with high timing resolution using embedded phase-locked loops.

    PubMed

    Smith, Peter R; Cowell, David M J; Raiton, Benjamin; Ky, Chau Vo; Freear, Steven

    2012-01-01

    Coarse time quantization of delay profiles within ultrasound array systems can produce undesirable side lobes in the radiated beam profile. The severity of these side lobes is dependent upon the magnitude of phase quantization error--the deviation from ideal delay profiles to the achievable quantized case. This paper describes a method to improve interchannel delay accuracy without increasing system clock frequency by utilizing embedded phase-locked loop (PLL) components within commercial field-programmable gate arrays (FPGAs). Precise delays are achieved by shifting the relative phases of embedded PLL output clocks in 208-ps steps. The described architecture can achieve the necessary interelement timing resolution required for driving ultrasound arrays up to 50 MHz. The applicability of the proposed method at higher frequencies is demonstrated by extrapolating experimental results obtained using a 5-MHz array transducer. Results indicate an increase in transmit dynamic range (TDR) when using accurate delay profiles generated by the embedded-PLL method described, as opposed to using delay profiles quantized to the system clock.

  9. 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.

  10. Newmark-Beta-FDTD method for super-resolution analysis of time reversal waves

    NASA Astrophysics Data System (ADS)

    Shi, Sheng-Bing; Shao, Wei; Ma, Jing; Jin, Congjun; Wang, Xiao-Hua

    2017-09-01

    In this work, a new unconditionally stable finite-difference time-domain (FDTD) method with the split-field perfectly matched layer (PML) is proposed for the analysis of time reversal (TR) waves. The proposed method is very suitable for multiscale problems involving microstructures. The spatial and temporal derivatives in this method are discretized by the central difference technique and Newmark-Beta algorithm, respectively, and the derivation results in the calculation of a banded-sparse matrix equation. Since the coefficient matrix keeps unchanged during the whole simulation process, the lower-upper (LU) decomposition of the matrix needs to be performed only once at the beginning of the calculation. Moreover, the reverse Cuthill-Mckee (RCM) technique, an effective preprocessing technique in bandwidth compression of sparse matrices, is used to improve computational efficiency. The super-resolution focusing of TR wave propagation in two- and three-dimensional spaces is included to validate the accuracy and efficiency of the proposed method.

  11. 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.

  12. 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.

  13. Real-Time Motion Correction for High-Resolution Larynx Imaging

    PubMed Central

    Barral, Joëlle K.; Santos, Juan M.; Damrose, Edward J.; Fischbein, Nancy J.; Nishimura, Dwight G.

    2012-01-01

    Motion—both rigid-body and non-rigid—is the main limitation to in vivo, high-resolution larynx imaging. In this work, a new real-time motion compensation algorithm is introduced. Navigator data are processed in real-time to compute the displacement information, and projections are corrected using phase-modulation in k-space. Upon automatic feedback, the system immediately reacquires the data most heavily corrupted by non-rigid motion, i.e., the data whose corresponding projections could not be properly corrected. This algorithm overcomes the shortcomings of the so-called Diminishing Variance Algorithm (DVA) by combining it with navigator-based rigid-body motion correction. Because rigid-body motion correction is performed first, continual bulk motion no longer impedes nor prevents the convergence of the algorithm. Phantom experiments show that the algorithm properly corrects for translations and reacquires data corrupted by non-rigid motion. Larynx imaging was performed on healthy volunteers, and substantial reduction of motion artifacts caused by bulk shift, swallowing, and coughing was achieved. PMID:21695722

  14. 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.

  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. 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.

  17. 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

  18. Real-time person detection in low-resolution thermal infrared imagery with MSER and CNNs

    NASA Astrophysics Data System (ADS)

    Herrmann, Christian; Müller, Thomas; Willersinn, Dieter; Beyerer, Jürgen

    2016-10-01

    In many camera-based systems, person detection and localization is an important step for safety and security applications such as search and rescue, reconnaissance, surveillance, or driver assistance. Long-wave infrared (LWIR) imagery promises to simplify this task because it is less affected by background clutter or illumination changes. In contrast to a lot of related work, we make no assumptions about any movement of persons or the camera, i.e. persons may stand still and the camera may move or any combination thereof. Furthermore, persons may appear arbitrarily in near or far distances to the camera leading to low-resolution persons in far distances. To address this task, we propose a two-stage system, including a proposal generation method and a classifier to verify, if the detected proposals really are persons. In contradiction to use all possible proposals as with sliding window approaches, we apply Maximally Stable Extremal Regions (MSER) and classify the detected proposals afterwards with a Convolutional Neural Network (CNN). The MSER algorithm acts as a hot spot detector when applied to LWIR imagery. Because the body temperature of persons is usually higher than the background, they appear as hot spots in the image. However, the MSER algorithm is unable to distinguish between different kinds of hot spots. Thus, all further LWIR sources such as windows, animals or vehicles will be detected, too. Still by applying MSER, the number of proposals is reduced significantly in comparison to a sliding window approach which allows employing the high discriminative capabilities of deep neural networks classifiers that were recently shown in several applications such as face recognition or image content classification. We suggest using a CNN as classifier for the detected hot spots and train it to discriminate between person hot spots and all further hot spots. We specifically design a CNN that is suitable for the low-resolution person hot spots that are common with

  19. A Real-Time Global Half-Hourly Pixel-Resolution Infrared Dataset and Its Applications.

    NASA Astrophysics Data System (ADS)

    Janowiak, John E.; Joyce, Robert J.; Yarosh, Yelena

    2001-02-01

    A system has been developed and implemented that merges pixel resolution (~4 km) infrared (IR) satellite data from all available geostationary meteorological satellites into a global (60°N-60°S) product. The resulting research-quality, nearly seamless global array of information is made possible by recent work by Joyce et al., who developed a technique to correct IR temperatures at targets far from satellite nadir. At such locations, IR temperatures are colder than if identical features were measured at a target near satellite nadir. This correction procedure yields a dataset that is considerably more amenable to quantitative manipulation than if the data from the individual satellites were merely spliced together.Several unique features of this product exist. First, the data from individual geostationary satellites have been merged to form nearly seamless maps after correcting the IR brightness temperatures for viewing angle effects. Second, with the availability of IR data from the Meteosat-5 satellite (currently positioned at a subsatellite longitude of 63°E), globally complete (60°N-60°S) fields can be produced. Third, the data have been transformed from the native satellite projection of each individual geostationary satellite and have been remapped to a uniform latitude/longitude grid. Fourth, globally merged datasets of full resolution IR brightness temperature have been produced routinely every half hour since November 1998. Fifth, seven days of globally merged, half-hourly data are available on a rotating archive that is maintained by the Climate Prediction Center Web page (http: /www.cpc.ncep.noaa.gov/products/global-precip/html/web.html). Unfortunately, international agreement prevents us from distributing Meteosat data within three days of real time, so the data availability is delayed appropriately. Finally, these data are permanently saved at the National Climatic Data Center in Asheville, North Carolina, beginning with data in mid-September of

  20. Characterization of space-time rainfall patterns over Switzerland based on high-resolution radar images

    NASA Astrophysics Data System (ADS)

    Benoit, Lionel; Mariethoz, Gregoire; Vrac, Mathieu

    2017-04-01

    Rainfall is generated by diverse and complex processes that produce rain fields with a large variability of patterns. High-resolution measurements of rainfall, provided for instance by networks of terrestrial weather radars, allow observing the spatial variability of rainfall patterns and its temporal evolution. The characterization of these space-time rainfall patterns is important for both the understanding of rain generation processes and the study of environmental impacts of rainfall on hydrology, erosion or plants growth, among others. Here we propose to study rainfall patterns using image processing methods on high-resolution radar images (1km x 1km x 1min) over Switzerland. The time series of radar images is first segmented in rain events. Then, the spatial structure of each rain event is characterized by computing statistics over several geometrical indices extracted from radar images, by adapting to the context of mid-latitude rainfalls the indices proposed by Aghakouchak, Nasrollahi et al. (2011) and Zick and Matyas (2016) for tropical rainfall characterization. Finally, the dynamics of rainfall patterns is characterized by estimating rain advection through image correlation, and by quantifying the temporal morphing of spatial patterns in a Lagrangian reference frame, where radar images are re-projected to cancel out rain advection. Two years of data (2015 - 2016) are used to investigate the variability of rainfall patterns over Switzerland. Typical values of the indicators measuring rainfall patterns and their dynamics are extracted for different areas, namely the Jura Mountain, the Swiss Plateau and the Alps. These measures of rainfall variability could be subsequently used to parameterize local weather generators or to investigate the relationships between rainfall patterns and atmospheric synoptic conditions. References: Aghakouchak, A., N. Nasrollahi, J. Li, B. Imam and S. Sorooshian (2011). "Geometrical Characterization of Precipitation Patterns