[Blood pressure in 6 Yanomami villages].

PubMed

Mancilha-Carvalho, J J; Sousa e Silva, N A; Carvalho, J V; Lima, J A

1991-06-01

To investigate in Yanomami Indians that not add salt to food, the relationship between blood pressure (BP), biological variables (age, body weight, height and pulse) and urinary electrolytes (Na+, K+, Ca++ and Mg++). We studied 125 males and 129 females from six villages on Surucuru plateau and on Catrimani and Ajarani rivers region in the state of Roraima, north Brazil. Two BP measurements were made and the mean of them were used in data analysis. None hypertensive was found. Systolic BP decreased with age and correlated with body weight, pulse and urinary Na+. Diastolic BP only correlated with body weight. Height, urinary K+, Ca++ and Mg++ did not correlate with BP. There was no hypertension nor increase of BP with increasing age in these isolated Yanomami.

A simple and versatile data acquisition system for software coincidence and pulse-height discrimination in 4πβ-γ coincidence experiments.

PubMed

Kawada, Y; Yamada, T; Unno, Y; Yunoki, A; Sato, Y; Hino, Y

2012-09-01

A simple but versatile data acquisition system for software coincidence experiments is described, in which any time stamping and live time controller are not provided. Signals from β- and γ-channels are fed to separately two fast ADCs (16 bits, 25 MHz clock maximum) via variable delay circuits and pulse-height stretchers, and also to pulse-height discriminators. The discriminating level was set to just above the electronic noise. Two ADCs were controlled with a common clock signal, and triggered simultaneously by the logic OR pulses from both discriminators. Paired digital signals for each sampling were sent to buffer memories connected to main PC with a FIFO (First-In, First-Out) pipe via USB. After data acquisition in list mode, various processing including pulse-height analyses was performed using MS-Excel (version 2007 and later). The usefulness of this system was demonstrated for 4πβ(PS)-4πγ coincidence measurements of (60)Co, (134)Cs and (152)Eu. Possibilities of other extended applications will be touched upon. Copyright © 2012 Elsevier Ltd. All rights reserved.

A pulsed jumping ring apparatus for demonstration of Lenz's law

NASA Astrophysics Data System (ADS)

Tanner, Paul; Loebach, Jeff; Cook, James; Hallen, H. D.

2001-08-01

Lenz's law is often demonstrated in classrooms by the use of Elihu Thomson's jumping ring. However, it is ironic that a thorough analysis of the physics of the ac jumping ring reveals that the operation is due mainly to a phase difference, not Lenz's law. A complete analysis of the physics behind the ac jumping ring is difficult for the introductory student. We present a design for a pulsed jumping ring which can be fully described by the application of Lenz's law. Other advantages of this system are that it lends itself to a rigorous analysis of the force balances and energy flow. The simple jumping ring apparatus closely resembles Thomson's, but is powered by a capacitor bank. The jump heights were measured for several rings as a function of energy stored in the capacitors. A simple model describes the data well. Currents in both the drive coil and ring are measured and that of the drive coil modeled to illuminate some properties of the capacitors. An analysis of the energy flow in the system explains the higher jump heights, to 2 m, when the ring is cooled.

Method for detecting and distinguishing between specific types of environmental radiation using a high pressure ionization chamber with pulse-mode readout

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

Degtiarenko, Pavel V.

An environmental radiation detector for detecting and distinguishing between all types of environmental radiation, including photons, charged particles, and neutrons. A large volume high pressure ionization chamber (HPIC) includes BF.sub.3 gas at a specific concentration to render the radiation detector sensitive to the reactions of neutron capture in Boron-10 isotope. A pulse-mode readout is connected to the ionization chamber capable of measuring both the height and the width of the pulse. The heavy charged products of the neutron capture reaction deposit significant characteristic energy of the reaction in the immediate vicinity of the reaction in the gas, producing a signalmore » with a pulse height proportional to the reaction energy, and a narrow pulse width corresponding to the essentially pointlike energy deposition in the gas. Readout of the pulse height and the pulse width parameters of the signals enables distinguishing between the different types of environmental radiation, such as gamma (x-rays), cosmic muons, and neutrons.« less

Design and Performance of the Astro-E/XRS Signal Processing System

NASA Technical Reports Server (NTRS)

Boyce, Kevin R.; Audley, M. D.; Baker, R. G.; Dumonthier, J. J.; Fujimoto, R.; Gendreau, K. C.; Ishisaki, Y.; Kelley, R. L.; Stahle, C. K.; Szymkowiak, A. E.

1999-01-01

We describe the signal processing system of the Astro-E XRS instrument. The Calorimeter Analog Processor (CAP) provides bias and power for the detectors and amplifies the detector signals by a factor of 20,000. The Calorimeter Digital Processor (CDP) performs the digital processing of the calorimeter signals, detecting X-ray pulses and analyzing them by optimal filtering. We describe the operation of pulse detection, Pulse height analysis. and risetime determination. We also discuss performance, including the three event grades (hi-res mid-res, and low-res). anticoincidence detection, counting rate dependence, and noise rejection.

Observation of radiation damage induced by single-ion hits at the heavy ion microbeam system

NASA Astrophysics Data System (ADS)

Kamiya, Tomihiro; Sakai, Takuro; Hirao, Toshio; Oikawa, Masakazu

2001-07-01

A single-ion hit system combined with the JAERI heavy ion microbeam system can be applied to observe individual phenomena induced by interactions between high-energy ions and a semiconductor device using a technique to measure the pulse height of transient current (TC) signals. The reduction of the TC pulse height for a Si PIN photodiode was measured under irradiation of 15 MeV Ni ions onto various micron-sized areas in the diode. The data containing damage effect by these irradiations were analyzed with least-square fitting using a Weibull distribution function. Changes of the scale and the shape parameters as functions of the width of irradiation areas brought us an assumption that a charge collection in a diode has a micron level lateral extent larger than a spatial resolution of the microbeam at 1 μm. Numerical simulations for these measurements were made with a simplified two-dimensional model based on this assumption using a Monte Carlo method. Calculated data reproducing the pulse-height reductions by single-ion irradiations were analyzed using the same function as that for the measurement. The result of this analysis, which shows the same tendency in change of parameters as that by measurements, seems to support our assumption.

Pulse Height Analyzer Interfacing and Computer Programming in the Environmental Laser Propagation Project

DTIC Science & Technology

1976-06-01

United States Naval Postgraduate School, Monterey , California, 1974. 6. Anton , H., Elementary Linear Algebra , John Wiley & Sons, 1973. 7. Parrat, L. G...CONVERTER ln(laser & bias) PULSE HEIGHT ANALYZER © LINEAR AMPLIFIER SAMPLE TRIGGER OSCILLATOR early ln(laser & bias) SCINTILLOMETERS recent BACKGROUND...DEMODULATOR LASER CALIBRATION BOX LASER OR CAL VOLTAGE LOG CONVERTER LN (LASER OR CAL VOLT) LINEAR AMPLIFIER uLN (LASER OR CAL VOLT) PULSE HEIGHTEN ANALYZER V

Digital pulse processing and electronic noise analysis for improving energy resolutions in planar TlBr detectors

NASA Astrophysics Data System (ADS)

Tada, Tsutomu; Hitomi, Keitaro; Tanaka, Tomonobu; Wu, Yan; Kim, Seong-Yun; Yamazaki, Hiromichi; Ishii, Keizo

2011-05-01

Digital pulse processing and electronic noise analysis are proposed for improving energy resolution in planar thallium bromide (TlBr) detectors. An energy resolution of 5.8% FWHM at 662 keV was obtained from a 0.5 mm thick planar TlBr detector at room temperature using a digitizer with a sampling rate of 100 MS/s and 8 bit resolution. The electronic noise in the detector-preamplifier system was measured as a function of pulse shaping time in order to investigate the optimum shaping time for the detector. The depth of interaction (DOI) in TlBr detectors for incident gamma-rays was determined by taking the ratio of pulse heights for fast-shaped to slow-shaped signals. FWHM energy resolution of the detector was improved from 5.8% to 4.2% by implementing depth correction and by using the obtained optimum shaping time.

Effects of pulse width and coding on radar returns from clear air

NASA Technical Reports Server (NTRS)

Cornish, C. R.

1983-01-01

In atmospheric radar studies it is desired to obtain maximum information about the atmosphere and to use efficiently the radar transmitter and processing hardware. Large pulse widths are used to increase the signal to noise ratio since clear air returns are generally weak and maximum height coverage is desired. Yet since good height resolution is equally important, pulse compression techniques such as phase coding are employed to optimize the average power of the transmitter. Considerations in implementing a coding scheme and subsequent effects of an impinging pulse on the atmosphere are investigated.

Modeling Sodium Iodide Detector Response Using Parametric Equations

DTIC Science & Technology

2013-03-22

MCNP particle current and pulse height tally functions, backscattering photons are quantified as a function of material thickness and energy...source – detector – scattering medium arrangements were modeled in MCNP using the pulse height tally functions, integrated over a 70 keV – 360 keV energy...15  4.1  MCNP

Development of MCNPX-ESUT computer code for simulation of neutron/gamma pulse height distribution

NASA Astrophysics Data System (ADS)

Abolfazl Hosseini, Seyed; Vosoughi, Naser; Zangian, Mehdi

2015-05-01

In this paper, the development of the MCNPX-ESUT (MCNPX-Energy Engineering of Sharif University of Technology) computer code for simulation of neutron/gamma pulse height distribution is reported. Since liquid organic scintillators like NE-213 are well suited and routinely used for spectrometry in mixed neutron/gamma fields, this type of detectors is selected for simulation in the present study. The proposed algorithm for simulation includes four main steps. The first step is the modeling of the neutron/gamma particle transport and their interactions with the materials in the environment and detector volume. In the second step, the number of scintillation photons due to charged particles such as electrons, alphas, protons and carbon nuclei in the scintillator material is calculated. In the third step, the transport of scintillation photons in the scintillator and lightguide is simulated. Finally, the resolution corresponding to the experiment is considered in the last step of the simulation. Unlike the similar computer codes like SCINFUL, NRESP7 and PHRESP, the developed computer code is applicable to both neutron and gamma sources. Hence, the discrimination of neutron and gamma in the mixed fields may be performed using the MCNPX-ESUT computer code. The main feature of MCNPX-ESUT computer code is that the neutron/gamma pulse height simulation may be performed without needing any sort of post processing. In the present study, the pulse height distributions due to a monoenergetic neutron/gamma source in NE-213 detector using MCNPX-ESUT computer code is simulated. The simulated neutron pulse height distributions are validated through comparing with experimental data (Gohil et al. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 664 (2012) 304-309.) and the results obtained from similar computer codes like SCINFUL, NRESP7 and Geant4. The simulated gamma pulse height distribution for a 137Cs source is also compared with the experimental data.

Measured neutron and gamma spectra from californium-252 in a tissue-equivalent medium.

PubMed

Elson, H R; Stupar, T A; Shapiro, A; Kereiakes, J G

1979-01-01

A method of experimentally obtaining both neutron and gamma-ray spectra in a scattering medium is described. The method utilizes a liquid-organic scintillator (NE-213) coupled with a pulse-shape discrimination circuit. This allows the separation of the neutron-induced pulse-height data from the gamma-ray pulse-height data. Using mathematical unfolding techniques, the two sets of pulse-height data were transformed to obtain the neutron and gamma-ray energy spectra. A small spherical detector was designed and constructed to reduce the errors incurred by attempting spectral measurements in a scattering medium. Demonstration of the utility of the system to obtain the neutron and gamma-ray spectra in a scattering medium was performed by characterizing the neutron and gamma-ray spectra at various sites about a 3.7-microgram (1.5 cm active length) californium-252 source in a tissue-equivalent medium.

High-resolution studies of the HF ionospheric modification interaction region

NASA Technical Reports Server (NTRS)

Duncan, L. M.; Sheerin, J. P.

1985-01-01

The use of the pulse edge analysis technique to explain ionospheric modifications caused by high-power HF radio waves is discussed. The technique, implemented at the Arecibo Observatory, uses long radar pulses and very rapid data sampling. A comparison of the pulse leading and trailing edge characteristics is obtained and the comparison is used to estimate the relative changes in the interaction region height and layer width; an example utilizing this technique is provided. Main plasma line overshoot and miniovershoot were studied from the pulse edge observations; the observations at various HF pulsings and radar resolutions are graphically presented. From the pulse edge data the development and the occurrence of main plasma line overshoot and miniovershoot are explained. The theories of soliton formation and collapse, wave ducting, profile modification, and parametric instabilities are examined as a means of explaining main plasma line overshoots and miniovershoots.

Network performance analysis and management for cyber-physical systems and their applications

NASA Astrophysics Data System (ADS)

Emfinger, William A.

With increased public interest in protecting the environment, scientists and engineers aim to improve energy conversion efficiency. Thermoelectrics offer many advantages as thermal management technology. When compared to vapor compression refrigeration, above approximately 200 to 600 watts, cost in dollars per watt as well as COP are not advantageous for thermoelectrics. The goal of this work was to determine if optimized pulse supercooling operation could improve cooling capacity or efficiency of a thermoelectric device. The basis of this research is a thermal-electrical analogy based modeling study using SPICE. Two models were developed. The first model, a standalone thermocouple with no attached mass to be cooled. The second, a system that includes a module attached to a heat generating mass. With the thermocouple study, a new approach of generating response surfaces with characteristic parameters was applied. The current pulse height and pulse on-time was identified for maximizing Net Transient Advantage, a newly defined metric. The corresponding pulse height and pulse on-time was utilized for the system model. Along with the traditional steady state starting current of Imax, Iopt was employed. The pulse shape was an isosceles triangle. For the system model, metrics new to pulse cooling were Qc, power consumption and COP. The effects of optimized current pulses were studied by changing system variables. Further studies explored time spacing between pulses and temperature distribution in the thermoelement. It was found net Q c over an entire pulse event can be improved over Imax steady operation but not over steady I opt operation. Qc can be improved over Iopt operation but only during the early part of the pulse event. COP is reduced in transient pulse operation due to the different time constants of Qc and Pin. In some cases lower performance interface materials allow more Qc and better COP during transient operation than higher performance interface materials. Important future work might look at developing innovative ways of biasing Joule heat to Th..

The Geoscience Laser Altimeter System (GLAS) for the ICESAT Mission

NASA Technical Reports Server (NTRS)

Abshire, James B.; Sun, Xiao-Li; Ketchum, Eleanor A.; Afzal, Robert S.; Millar, Pamela S.

1999-01-01

Accurate measurements of surface heights and atmospheric backscatter have been demonstrated with the SLA, MOLA and LITE space lidar. Recent MOLA measurements of the Mars surface have 40 cm resolution and have reduced the global uncertainty in Mars topography from a few km to approx. 10 m. GLAS is a next generation lidar being developed as part of NASA's Icesat Mission for Earth orbit . The GLAS design combines a 10 cm precision surface lidar with a sensitive dual wavelength cloud and aerosol lidar. GLAS will precisely measure the heights of the Earth's polar ice sheets, determine the height profiles of the Earth's land topography, and profile the vertical backscatter of clouds and aerosols on a global scale. GLAS will fly on a small dedicated spacecraft in a polar orbit at 598 km altitude with an inclination of 94 degrees. GLAS is scheduled to launch in summer 2001 and to operate continuously for a minimum of 3 years with a goal of 5 years. The primary mission for GLAS is to measure the seasonal and annual changes in the heights of the Greenland and Antarctic ice sheets. GLAS will measure the vertical distance to the ice sheet from orbit with 1064 nm pulses from a Nd:Yag laser at 40 Hz. Each 5 nsec wide laser pulse is used for a single range measurement. When over land GLAS will profile the heights of the topography and vegetation. The GLAS receiver uses a I m diameter telescope and a Si APD detector. The detector signal is sampled by an all digital receiver which records each surface echo waveform with I nsec resolution and a stored echo record lengths of either 200, 400, or 600 samples. Analysis of the echo waveforms within the instrument permits discrimination between cloud and surface echoes. Ground based echo analysis permits precise ranging, determining the roughness or slopes of the surface as well as the vertical distributions of vegetation illuminated by the laser, Errors in knowledge of the laser beam pointing angle can bias height measurements of sloped surfaces. For surfaces with 2 deg. slopes, knowledge of pointing angle of the beam centroid to about 8 urad is required to achieve 10 cm height accuracy. GLAS uses a stellar reference system (SRS) to determine the pointing angle of each laser firing relative to inertial space. The SRS uses a high precision star camera oriented toward local zenith whose measurements are combined with a gyroscope to determine the inertial orientation of the SRS optical bench. The far field pattern of each laser pulse is measured with a laser reference system (LRS). Optically measuring each laser far field pattern relative to the star camera and gyroscope permits the angular offsets of each laser pulse to be determined. GLAS will also determine the vertical distributions of clouds and aerosols by measuring atmospheric backscatter profiles at both 1064 and 532 nm. The 1064 nm measurements use an analog detector and profile the height and vertical structure of thicker clouds. Measurements at 532 nm use new highly sensitive photon counting detectors, and measure the height distributions of very thin clouds and aerosol layers. With averaging these can be used to determine the height of the planetary boundary layer. The instrument design and expected performance will be discussed.

PULSE AMPLITUDE ANALYZER

DOEpatents

Gray, G.W.; Jensen, A.S.

1957-10-22

A pulse-height analyzer system of improved design for sorting and counting a series of pulses, such as provided by a scintillation detector in nuclear radiation measurements, is described. The analyzer comprises a main transmission line, a cathode-ray tube for each section of the line with its deflection plates acting as the line capacitance; means to bias the respective cathode ray tubes so that the beam strikes a target only when a prearranged pulse amplitude is applied, with each tube progressively biased to respond to smaller amplitudes; pulse generating and counting means associated with each tube to respond when the beam is deflected; a control transmission line having the same time constant as the first line per section with pulse generating means for each tube for initiating a pulse on the second transmission line when a pulse triggers the tube of corresponding amplitude response, the former pulse acting to prevent successive tubes from responding to the pulse under test. This arrangement permits greater deflection sensitivity in the cathode ray tube and overcomes many of the disadvantages of prior art pulse-height analyzer circuits.

Comparison of Regression Analysis and Transfer Function in Estimating the Parameters of Central Pulse Waves from Brachial Pulse Wave.

PubMed

Chai, Rui; Xu, Li-Sheng; Yao, Yang; Hao, Li-Ling; Qi, Lin

2017-01-01

This study analyzed ascending branch slope (A_slope), dicrotic notch height (Hn), diastolic area (Ad) and systolic area (As) diastolic blood pressure (DBP), systolic blood pressure (SBP), pulse pressure (PP), subendocardial viability ratio (SEVR), waveform parameter (k), stroke volume (SV), cardiac output (CO), and peripheral resistance (RS) of central pulse wave invasively and non-invasively measured. Invasively measured parameters were compared with parameters measured from brachial pulse waves by regression model and transfer function model. Accuracy of parameters estimated by regression and transfer function model, was compared too. Findings showed that k value, central pulse wave and brachial pulse wave parameters invasively measured, correlated positively. Regression model parameters including A_slope, DBP, SEVR, and transfer function model parameters had good consistency with parameters invasively measured. They had same effect of consistency. SBP, PP, SV, and CO could be calculated through the regression model, but their accuracies were worse than that of transfer function model.

A system for measuring the pulse height distribution of ultrafast photomultipliers

NASA Technical Reports Server (NTRS)

Abshire, J. B.

1977-01-01

A system for measuring the pulse height distribution of gigahertz bandwidth photomultipliers was developed. This system uses a sampling oscilloscope as a sample-hold circuit and has a bandwidth of 12 gigahertz. Test results are given for a static crossed-filed photomultiplier tested with a demonstration system. Calculations on system amplitude resolution capabilities are included for currently available system components.

Single-particle detection of products from atomic and molecular reactions in a cryogenic ion storage ring

NASA Astrophysics Data System (ADS)

Krantz, C.; Novotný, O.; Becker, A.; George, S.; Grieser, M.; Hahn, R. von; Meyer, C.; Schippers, S.; Spruck, K.; Vogel, S.; Wolf, A.

2017-04-01

We have used a single-particle detector system, based on secondary electron emission, for counting low-energetic (∼keV/u) massive products originating from atomic and molecular ion reactions in the electrostatic Cryogenic Storage Ring (CSR). The detector is movable within the cryogenic vacuum chamber of CSR, and was used to measure production rates of a variety of charged and neutral daughter particles. In operation at a temperature of ∼ 6 K , the detector is characterised by a high dynamic range, combining a low dark event rate with good high-rate particle counting capability. On-line measurement of the pulse height distributions proved to be an important monitor of the detector response at low temperature. Statistical pulse-height analysis allows to infer the particle detection efficiency of the detector, which has been found to be close to unity also in cryogenic operation at 6 K.

Fusion neutron detector for time-of-flight measurements in z-pinch and plasma focus experiments.

PubMed

Klir, D; Kravarik, J; Kubes, P; Rezac, K; Litseva, E; Tomaszewski, K; Karpinski, L; Paduch, M; Scholz, M

2011-03-01

We have developed and tested sensitive neutron detectors for neutron time-of-flight measurements in z-pinch and plasma focus experiments with neutron emission times in tens of nanoseconds and with neutron yields between 10(6) and 10(12) per one shot. The neutron detectors are composed of a BC-408 fast plastic scintillator and Hamamatsu H1949-51 photomultiplier tube (PMT). During the calibration procedure, a PMT delay was determined for various operating voltages. The temporal resolution of the neutron detector was measured for the most commonly used PMT voltage of 1.4 kV. At the PF-1000 plasma focus, a novel method of the acquisition of a pulse height distribution has been used. This pulse height analysis enabled to determine the single neutron sensitivity for various neutron energies and to calibrate the neutron detector for absolute neutron yields at about 2.45 MeV.

Octave-spanning supercontinuum generation in a silicon-rich nitride waveguide.

PubMed

Liu, Xing; Pu, Minhao; Zhou, Binbin; Krückel, Clemens J; Fülöp, Attila; Torres-Company, Victor; Bache, Morten

2016-06-15

We experimentally show octave-spanning supercontinuum generation in a nonstoichiometric silicon-rich nitride waveguide when pumped by femtosecond pulses from an erbium fiber laser. The pulse energy and bandwidth are comparable to results achieved in stoichiometric silicon nitride waveguides, but our material platform is simpler to manufacture. We also observe wave-breaking supercontinuum generation by using orthogonal pumping in the same waveguide. Additional analysis reveals that the waveguide height is a powerful tuning parameter for generating mid-infrared dispersive waves while keeping the pump in the telecom band.

[Clinical factors relating to the arterial elastic function measured by PWV, C1/C2 and AI in hypertensive patients].

PubMed

Cai, Kai-yu; Zhang, Wei-zhong; Qiu, Hui-li; Wu, Mei-zhi

2007-03-01

To analyze the clinical factors relating to arterial elastic function measured with pulse wave velocity (PWV), large and small arterial elastic indexes (C(1) and C(2)) and augmentation index (AI) in hypertensive patients. A total of 2176 hypertensive patients were enrolled and divided into three groups: Elastic function was measured in 1100 subjects by (PWV), in 647 subjects by C(1) and C(2) and in 429 by AI. PWV was positively correlated with age, systolic pressure, pulse pressure and negatively correlated with body height and weights (all P < 0.05). C(1) and C(2) values were higher in male than that in female patients (P < 0.01) and negatively correlated with age, systolic pressure, pulse pressure and heart rate while positively correlated with body height, weight and body mass index. In hypercholesterolemia patients (n = 168), C(1) and C(2) were negatively correlated with serum cholesterol level (P < 0.05). AI value was higher in female than that in male patients (P < 0.01) and positively correlated with age, systolic pressure, diastolic pressure, pulse pressure while negatively correlated with body height, weight and heart rate. Age, systolic and pulse pressure as well as body height and weights are the main factors correlated to arterial elastic function measured by PWV, C(1) and C(2) and AI.

Using Poisson-regularized inversion of Bremsstrahlung emission to extract full electron energy distribution functions from x-ray pulse-height detector data

NASA Astrophysics Data System (ADS)

Swanson, C.; Jandovitz, P.; Cohen, S. A.

2018-02-01

We measured Electron Energy Distribution Functions (EEDFs) from below 200 eV to over 8 keV and spanning five orders-of-magnitude in intensity, produced in a low-power, RF-heated, tandem mirror discharge in the PFRC-II apparatus. The EEDF was obtained from the x-ray energy distribution function (XEDF) using a novel Poisson-regularized spectrum inversion algorithm applied to pulse-height spectra that included both Bremsstrahlung and line emissions. The XEDF was measured using a specially calibrated Amptek Silicon Drift Detector (SDD) pulse-height system with 125 eV FWHM at 5.9 keV. The algorithm is found to out-perform current leading x-ray inversion algorithms when the error due to counting statistics is high.

Environmental Survey of the B-3 and Ford’s Farm Ranges,

DTIC Science & Technology

1983-08-01

reported have an estimated analytical error of *35% unless noted otherwise. 14 Isotopic Analysis The isotopic uranium analysis procedure used by UST...sulfate buffer and elec- trodeposited on a stainless steel disc, and isotopes of uranium (234U, 23 5U, and 2 38U) were determined by pulse height analysis ...measurements and some environmental sampling. Several special studies were also conducted, including analyses of the isotopic composition of uranium in

Stabilization of Particle Discrimination Efficiencies for Neutron Spectrum Unfolding With Organic Scintillators

NASA Astrophysics Data System (ADS)

Lawrence, Chris C.; Polack, J. K.; Febbraro, Michael; Kolata, J. J.; Flaska, Marek; Pozzi, S. A.; Becchetti, F. D.

2017-02-01

The literature discussing pulse-shape discrimination (PSD) in organic scintillators dates back several decades. However, little has been written about PSD techniques that are optimized for neutron spectrum unfolding. Variation in n-γ misclassification rates and in γ/n ratio of incident fields can distort the neutron pulse-height response of scintillators and these distortions can in turn cause large errors in unfolded spectra. New applications in arms-control verification call for detection of lower-energy neutrons, for which PSD is particularly problematic. In this article, we propose techniques for removing distortions on pulse-height response that result from the merging of PSD distributions in the low-pulse-height region. These techniques take advantage of the repeatable shapes of PSD distributions that are governed by the counting statistics of scintillation-photon populations. We validate the proposed techniques using accelerator-based time-of-flight measurements and then demonstrate them by unfolding the Watt spectrum from measurement with a 252Cf neutron source.

An easy-to-operate portable pulse-height analysis system for area monitoring with TEPC in radiation protection

NASA Astrophysics Data System (ADS)

Kunz, A.; Pihet, P.; Arend, E.; Menzel, H. G.

1990-12-01

A portable area monitor for the measurement of dose-equivalent quantities in practical radiation-protection work has been developed. The detector applied is a low-pressure proportional counter (TEPC) used in microdosimetry. The complex analysis system required has been optimized with regard to low power consumption and small size to achieve a real operational survey meter. The newly designed electronic includes complete analog, digital and microprocessor boards. It presents the characteristic of fast pulse-height processing over a large (5 decades) dynamic range. Three original circuits have been specifically developed, consisting of: (1) a miniaturized adjustable high-voltage power supply with low ripple and high stability; (2) a double spectroscopy amplifier with constant gain ratio and common pole-zero stage; and (3) an analog-to-digital converter with quasi-logarithmic characteristics based on a flash converter using fast comparators associated in parallel. With the incorporated single-board computer, the maximal total power consumption is 5 W, enabling 40 hours operation time with batteries. With minor adaptations the equipment is proposed as a low-cost solution for various measuring problems in environmental studies.

Detection of Aspens Using High Resolution Aerial Laser Scanning Data and Digital Aerial Images

PubMed Central

Säynäjoki, Raita; Packalén, Petteri; Maltamo, Matti; Vehmas, Mikko; Eerikäinen, Kalle

2008-01-01

The aim was to use high resolution Aerial Laser Scanning (ALS) data and aerial images to detect European aspen (Populus tremula L.) from among other deciduous trees. The field data consisted of 14 sample plots of 30 m × 30 m size located in the Koli National Park in the North Karelia, Eastern Finland. A Canopy Height Model (CHM) was interpolated from the ALS data with a pulse density of 3.86/m2, low-pass filtered using Height-Based Filtering (HBF) and binarized to create the mask needed to separate the ground pixels from the canopy pixels within individual areas. Watershed segmentation was applied to the low-pass filtered CHM in order to create preliminary canopy segments, from which the non-canopy elements were extracted to obtain the final canopy segmentation, i.e. the ground mask was analysed against the canopy mask. A manual classification of aerial images was employed to separate the canopy segments of deciduous trees from those of coniferous trees. Finally, linear discriminant analysis was applied to the correctly classified canopy segments of deciduous trees to classify them into segments belonging to aspen and those belonging to other deciduous trees. The independent variables used in the classification were obtained from the first pulse ALS point data. The accuracy of discrimination between aspen and other deciduous trees was 78.6%. The independent variables in the classification function were the proportion of vegetation hits, the standard deviation of in pulse heights, accumulated intensity at the 90th percentile and the proportion of laser points reflected at the 60th height percentile. The accuracy of classification corresponded to the validation results of earlier ALS-based studies on the classification of individual deciduous trees to tree species. PMID:27873799

Theoretical and experimental investigations of coincidences in Poisson distributed pulse trains and spectral distortion caused by pulse pileup

NASA Astrophysics Data System (ADS)

Bristow, Quentin

1990-03-01

The occurrence rates of pulse strings, or sequences of pulses with interarrival times less than the resolving time of the pulse-height analysis system used to acquire spectra, are derived from theoretical considerations. Logic circuits were devised to make experimental measurements of multiple pulse string occurrence rates in the output from a scintillation detector over a wide range of count rates. Markov process theory was used to predict state transition rates in the logic circuits, enabling the experimental data to be checked rigorously for conformity with those predicted for a Poisson distribution. No fundamental discrepancies were observed. Monte Carlo simulations, incorporating criteria for pulse pileup inherent in the operation of modern analog to digital converters, were used to generate pileup spectra due to coincidences between two pulses (first order pileup) and three pulses (second order pileup) for different semi-Gaussian pulse shapes. Coincidences between pulses in a single channel produced a basic probability density function spectrum. The use of a flat spectrum showed the first order pileup distorted the spectrum to a linear ramp with a pileup tail. A correction algorithm was successfully applied to correct entire spectra (simulated and real) for first and second order pileups.

PULSE HEIGHT ANALYZER

DOEpatents

Johnstone, C.W.

1958-01-21

An anticoincidence device is described for a pair of adjacent channels of a multi-channel pulse height analyzer for preventing the lower channel from generating a count pulse in response to an input pulse when the input pulse has sufficient magnitude to reach the upper level channel. The anticoincidence circuit comprises a window amplifier, upper and lower level discriminators, and a biased-off amplifier. The output of the window amplifier is coupled to the inputs of the discriminators, the output of the upper level discriminator is connected to the resistance end of a series R-C network, the output of the lower level discriminator is coupled to the capacitance end of the R-C network, and the grid of the biased-off amplifier is coupled to the junction of the R-C network. In operation each discriminator produces a negative pulse output when the input pulse traverses its voltage setting. As a result of the connections to the R-C network, a trigger pulse will be sent to the biased-off amplifier when the incoming pulse level is sufficient to trigger only the lower level discriminator.

Impact of Spacecraft Shielding on Direct Ionization Soft Error Rates for sub-130 nm Technologies

NASA Technical Reports Server (NTRS)

Pellish, Jonathan A.; Xapsos, Michael A.; Stauffer, Craig A.; Jordan, Michael M.; Sanders, Anthony B.; Ladbury, Raymond L.; Oldham, Timothy R.; Marshall, Paul W.; Heidel, David F.; Rodbell, Kenneth P.

2010-01-01

We use ray tracing software to model various levels of spacecraft shielding complexity and energy deposition pulse height analysis to study how it affects the direct ionization soft error rate of microelectronic components in space. The analysis incorporates the galactic cosmic ray background, trapped proton, and solar heavy ion environments as well as the October 1989 and July 2000 solar particle events.

Impact of Spacecraft Shielding on Direct Ionization Soft Error Rates for Sub-130 nm Technologies

NASA Technical Reports Server (NTRS)

Pellish, Jonathan A.; Xapsos, Michael A.; Stauffer, Craig A.; Jordan, Thomas M.; Sanders, Anthony B.; Ladbury, Raymond L.; Oldham, Timothy R.; Marshall, Paul W.; Heidel, David F.; Rodbell, Kenneth P.

2010-01-01

We use ray tracing software to model various levels of spacecraft shielding complexity and energy deposition pulse height analysis to study how it affects the direct ionization soft error rate of microelectronic components in space. The analysis incorporates the galactic cosmic ray background, trapped proton, and solar heavy ion environments as well as the October 1989 and July 2000 solar particle events.

Neutron Detection With Ultra-Fast Digitizer and Pulse Identification Techniques on DIII-D

NASA Astrophysics Data System (ADS)

Zhu, Y. B.; Heidbrink, W. W.; Piglowski, D. A.

2013-10-01

A prototype system for neutron detection with an ultra-fast digitizer and pulse identification techniques has been implemented on the DIII-D tokamak. The system consists of a cylindrical neutron fission chamber, a charge sensitive amplifier, and a GaGe Octopus 12-bit CompuScope digitizer card installed in a Linux computer. Digital pulse identification techniques have been successfully performed at maximum data acquisition rate of 50 MSPS with on-board memory of 2 GS. Compared to the traditional approach with fast nuclear electronics for pulse counting, this straightforward digital solution has many advantages, including reduced expense, improved accuracy, higher counting rate, and easier maintenance. The system also provides the capability of neutron-gamma pulse shape discrimination and pulse height analysis. Plans for the upgrade of the old DIII-D neutron counting system with these techniques will be presented. Work supported by the US Department of Energy under SC-G903402, and DE-FC02-04ER54698.

Using Poisson-regularized inversion of Bremsstrahlung emission to extract full electron energy distribution functions from x-ray pulse-height detector data

DOE PAGES

Swanson, C.; Jandovitz, P.; Cohen, S. A.

2018-02-27

We measured Electron Energy Distribution Functions (EEDFs) from below 200 eV to over 8 keV and spanning five orders-of-magnitude in intensity, produced in a low-power, RF-heated, tandem mirror discharge in the PFRC-II apparatus. The EEDF was obtained from the x-ray energy distribution function (XEDF) using a novel Poisson-regularized spectrum inversion algorithm applied to pulse-height spectra that included both Bremsstrahlung and line emissions. The XEDF was measured using a specially calibrated Amptek Silicon Drift Detector (SDD) pulse-height system with 125 eV FWHM at 5.9 keV. Finally, the algorithm is found to out-perform current leading x-ray inversion algorithms when the error duemore » to counting statistics is high.« less

Using Poisson-regularized inversion of Bremsstrahlung emission to extract full electron energy distribution functions from x-ray pulse-height detector data

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

Swanson, C.; Jandovitz, P.; Cohen, S. A.

We measured Electron Energy Distribution Functions (EEDFs) from below 200 eV to over 8 keV and spanning five orders-of-magnitude in intensity, produced in a low-power, RF-heated, tandem mirror discharge in the PFRC-II apparatus. The EEDF was obtained from the x-ray energy distribution function (XEDF) using a novel Poisson-regularized spectrum inversion algorithm applied to pulse-height spectra that included both Bremsstrahlung and line emissions. The XEDF was measured using a specially calibrated Amptek Silicon Drift Detector (SDD) pulse-height system with 125 eV FWHM at 5.9 keV. Finally, the algorithm is found to out-perform current leading x-ray inversion algorithms when the error duemore » to counting statistics is high.« less

A rocket-borne pulse-height analyzer for energetic particle measurements

NASA Technical Reports Server (NTRS)

Leung, W.; Smith, L. G.; Voss, H. D.

1979-01-01

The pulse-height analyzer basically resembles a time-sharing multiplexing data-acquisition system which acquires analog data (from energetic particle spectrometers) and converts them into digital code. The PHA simultaneously acquires pulse-height information from the analog signals of the four input channels and sequentially multiplexes the digitized data to a microprocessor. The PHA together with the microprocessor form an on-board real-time data-manipulation system. The system processes data obtained during the rocket flight and reduces the amount of data to be sent back to the ground station. Consequently the data-reduction process for the rocket experiments is speeded up. By using a time-sharing technique, the throughput rate of the microprocessor is increased. Moreover, data from several particle spectrometers are manipulated to share one information channel; consequently, the TM capacity is increased.

Acoustics and hydrodynamics of a drop impact on a water surface

NASA Astrophysics Data System (ADS)

Chashechkin, Yu. D.; Prokhorov, V. E.

2017-01-01

Hydrodynamic and acoustic processes associated with a drop impact on a water surface were studied experimentally. Acoustic signals were detected underwater (with a hydrophone) and in air (with a microphone), the flow pattern was recorded with a high-speed camera, and the surface perturbation was monitored with a laser detector. The dimensionless parameters of flows (Reynolds, Froude, and Weber numbers) induced by the impact varied with fall height within the ranges of 5000 < Re < 20000, 20 < Fr < 350, and 70 < We < 1000. The sequence of acoustic signals incorporated an impact pulse at the moment of contact between a drop and the surface and a series of acoustic packets attributable to the resonance emission of gas cavities. The top of the impact pulse, which was detected clearly in the entire fall height range, had a complex structure with short high-frequency and longer low-frequency oscillations. The total number and the parameters of emitted acoustic packets depended to a considerable extent on the fall height. The cases of lacking, one-time, and repeated emission of packets were noted in a series of experiments performed at a constant fall height. The analysis of video data showed that the signal variability was induced by considerable differences in the scenarios of water entry of a drop, which assumed an ovoid shape at the end trajectory segment, in the mentioned experiments.

Theoretical and Experimental Investigations of Coincidences in Poisson Distributed Pulse Trains and Spectral Distortion Caused by Pulse Pileup.

NASA Astrophysics Data System (ADS)

Bristow, Quentin

1990-01-01

Part one of this two-part study is concerned with the multiple coincidences in pulse trains from X-ray and gamma radiation detectors which are the cause of pulse pileup. A sequence of pulses with inter-arrival times less than tau, the resolving time of the pulse-height analysis system used to acquire spectra, is called a multiple pulse string. Such strings can be classified on the basis of the number of pulses they contain, or the number of resolving times they cover. The occurrence rates of such strings are derived from theoretical considerations. Logic circuits were devised to make experimental measurements of multiple pulse string occurrence rates in the output from a NaI(Tl) scintillation detector over a wide range of count rates. Markov process theory was used to predict state transition rates in the logic circuits, enabling the experimental data to be checked rigorously for conformity with those predicted for a Poisson distribution. No fundamental discrepancies were observed. Part two of the study is concerned with a theoretical analysis of pulse pileup and the development of a discrete correction algorithm, based on the use of a function to simulate the coincidence spectrum produced by partial sums of pulses. Monte Carlo simulations, incorporating criteria for pulse pileup inherent in the operation of modern ADC's, were used to generate pileup spectra due to coincidences between two pulses, (1st order pileup) and three pulses (2nd order pileup), for different semi-Gaussian pulse shapes. Coincidences between pulses in a single channel produced a basic probability density function spectrum which can be regarded as an impulse response for a particular pulse shape. The use of a flat spectrum (identical count rates in all channels) in the simulations, and in a parallel theoretical analysis, showed the 1st order pileup distorted the spectrum to a linear ramp with a pileup tail. The correction algorithm was successfully applied to correct entire spectra for 1st and 2nd order pileup; both those generated by Monte Carlo simulations and in addition some real spectra acquired with a laboratory multichannel analysis system.

Pulse pile-up in hard X-ray detector systems. [for solar X-rays

NASA Technical Reports Server (NTRS)

Datlowe, D. W.

1975-01-01

When pulse-height spectra are measured by a nuclear detection system at high counting rates, the probability that two or more pulses will arrive within the resolving time of the system is significant. This phenomenon, pulse pile-up, distorts the pulse-height spectrum and must be considered in the interpretation of spectra taken at high counting rates. A computational technique for the simulation of pile-up is developed. The model is examined in the three regimes where (1) the time between pulses is long compared to the detector-system resolving time, (2) the time between pulses is comparable to the resolving time, and (3) many pulses occur within the resolving time. The technique is used to model the solar hard X-ray experiment on the OSO-7 satellite; comparison of the model with data taken during three large flares shows excellent agreement. The paper also describes rule-of-thumb tests for pile-up and identifies the important detector design factors for minimizing pile-up, i.e., thick entrance windows and short resolving times in the system electronics.

Semi-automated stand delineation in Mediterranean Pinus sylvestris plantations through segmentation of LiDAR data: The influence of pulse density

NASA Astrophysics Data System (ADS)

Varo-Martínez, Mª Ángeles; Navarro-Cerrillo, Rafael M.; Hernández-Clemente, Rocío; Duque-Lazo, Joaquín

2017-04-01

Traditionally, forest-stand delineation has been assessed based on orthophotography. The application of LiDAR has improved forest management by providing high-spatial-resolution data on the vertical structure of the forest. The aim of this study was to develop and test a semi-automated algorithm for stands delineation in a plantation of Pinus sylvestris L. using LiDAR data. Three specific objectives were evaluated, i) to assess two complementary LiDAR metrics, Assmann dominant height and basal area, for the characterization of the structure of P. sylvestris Mediterranean forests based on object-oriented segmentation, ii) to evaluate the influence of the LiDAR pulse density on forest-stand delineation accuracy, and iii) to investigate the algorithmś effectiveness in the delineation of P. sylvestris stands for map prediction of Assmann dominant height and basal area. Our results show that it is possible to generate accurate P. sylvestris forest-stand segmentations using multiresolution or mean shift segmentation methods, even with low-pulse-density LiDAR - which is an important economic advantage for forest management. However, eCognition multiresolution methods provided better results than the OTB (Orfeo Tool Box) for stand delineation based on dominant height and basal area estimations. Furthermore, the influence of pulse density on the results was not statistically significant in the basal area calculations. However, there was a significant effect of pulse density on Assmann dominant height [F2,9595 = 5.69, p = 0.003].for low pulse density. We propose that the approach shown here should be considered for stand delineation in other large Pinus plantations in Mediterranean regions with similar characteristics.

The HEAO-A Scanning Modulation Collimator instrument

NASA Technical Reports Server (NTRS)

Roy, A.; Ballas, J.; Jagoda, N.; Mckinnon, P.; Ramsey, A.; Wester, E.

1977-01-01

The Scanning Modulation Collimator X-ray instrument for the HEAO-A satellite was designed to measure celestial radiation in the range between 1 and 15 KeV and to resolve, and correlate, the position of X-ray sources with visible light sources on the celestial sphere to within 5 arc seconds. The positional accuracy is made possible by mechanical collimation of the X-ray sources viewed by the instrument. High sensitivity is provided from two systems each containing four gas filled proportional counters followed by preamplification, signal summing, pulse height analysis, pulse shape discrimination, X-ray event accumulators and telemetry processing electronics.

Pulse-Shape Analysis of Neutron-Induced Scintillation Light in Ni-doped 6LiF/ZnS

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

Cowles, Christian C.; Behling, Richard S.; Imel, G. R.

Abstract–Alternatives to 3He are being investigated for gamma-ray insensitive neutron detection applications, including plutonium assay. One promising material is lithium-6 fluoride with silver activated zinc sulfide 6LiF/ZnS(Ag) in conjunction with a wavelength shifting plastic. Doping the 6LiF/ZnS(Ag) with nickel (Ni) has been proposed as a means of reducing the decay time of neutron signal pulses. This research performed a pulse shape comparison between Ni-doped and non-doped 6LiF/ZnS(Ag) neutron pulses. The Ni-doped 6LiF/ZnS(Ag) had a 32.7% ± 0.3 increase in neutron pulse height and a 32.4% ± 0.3 decrease in neutron pulse time compared to the non-doped 6LiF/ZnS(Ag). Doping 6LiF/ZnS(Ag) withmore » nickel may allow neutron detector operation with improved signal to noise ratios, and reduced pulse pileup affects, increasing the accuracy and range of source activities with which such a detector could operate.« less

Signal Processing for Determining Water Height in Steam Pipes with Dynamic Surface Conditions

NASA Technical Reports Server (NTRS)

Lih, Shyh-Shiuh; Lee, Hyeong Jae; Bar-Cohen, Yoseph

2015-01-01

An enhanced signal processing method based on the filtered Hilbert envelope of the auto-correlation function of the wave signal has been developed to monitor the height of condensed water through the steel wall of steam pipes with dynamic surface conditions. The developed signal processing algorithm can also be used to estimate the thickness of the pipe to determine the cut-off frequency for the low pass filter frequency of the Hilbert Envelope. Testing and analysis results by using the developed technique for dynamic surface conditions are presented. A multiple array of transducers setup and methodology are proposed for both the pulse-echo and pitch-catch signals to monitor the fluctuation of the water height due to disturbance, water flow, and other anomaly conditions.

RISE TIME DELAY DISCRIMINATOR

DOEpatents

Johnstone, C.W.

1959-09-29

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

Analysis of LEAM experiment response to charged particles

NASA Technical Reports Server (NTRS)

Perkins, D.

1976-01-01

The objectives of the Lunar Ejecta and Meteorites Experiment (LEAM) were to measure the long-term variations in cosmic dust influx rates and the extent and nature of the lunar ejecta. While analyzing these characteristics in the data, it was discovered that a majority of the events could not be associated with hypervelocity particle impacts of the type usually identified with cosmic dust, but could only be correlated with the lunar surface and local sun angle. The possibility that charged particles could be incident on the sensors led to an analysis of the electronics to determine if such signals could cause the large pulse height analysis (PHA) signals. A qualitative analysis of the PHA circuit showed that an alternative mode of operation existed if the input signal were composed of pulses with pulse durations very long compared to the durations for which it was designed. This alternative mode would give large PHA outputs even though the actual input amplitudes were small. This revelation led to the examination of the sensor and its response to charged particles to determine the type of signals that could be expected.

The Geoscience Laser Altimeter System (GLAS) for the ICESAT Mission

NASA Technical Reports Server (NTRS)

Abshire, James B.; Sun, Xia-Li; Ketchum, Eleanor A.; Afzal, Robert S.; Millar, Pamela S.; Smith, David E. (Technical Monitor)

2000-01-01

The Laser In space Technology Experiment, Shuttle Laser Altimeter and the Mars Observer Laser Altimeter have demonstrated accurate measurements of atmospheric backscatter and Surface heights from space. The recent MOLA measurements of the Mars surface have 40 cm vertical resolution and have reduced the global uncertainty in Mars topography from a few km to about 5 m. The Geoscience Laser Altimeter System (GLAS) is a next generation lidar for Earth orbit being developed as part of NASA's Icesat Mission. The GLAS design combines a 10 cm precision surface lidar with a sensitive dual wavelength cloud and aerosol lidar. GLAS will precisely measure the heights of the Earth's polar ice sheets, establish a grid of accurate height profiles of the Earth's land topography, and profile the vertical backscatter of clouds and aerosols on a global scale. GLAS is being developed to fly on a small dedicated spacecraft in a polar orbit with a 590 630 km altitude at inclination of 94 degrees. GLAS is scheduled to launch in the summer 2001 and to operate continuously for a minimum of 3 years with a goal of 5 years. The primary mission for GLAS is to measure the seasonal and annual changes in the heights of the Greenland and Antarctic ice sheets. GLAS will continuously measure the vertical distance from orbit to the Earth's surface with 1064 nm pulses from a ND:YAG laser at a 40 Hz rate. Each 5 nsec wide laser pulse is used to produce a single range measurement, and the laser spots have 66 m diameter and about 170 m center-center spacings. When over land GLAS will profile the heights of the topography and vegetation. The GLAS receiver uses a 1 m diameter telescope and a Si APD detector. The detector signal is sampled by an all digital receiver which records each surface echo waveform with I nsec resolution and a stored echo record lengths of either 200, 400, or 600 samples. Analysis of the echo waveforms within the instrument permits discrimination between cloud and surface echoes. Ground based echo analysis permits precise ranging, determining the roughness or slopes of the surface as well as the vertical distributions of vegetation illuminated by the laser. Accurate knowledge of the laser beam's pointing angle is needed to prevent height biases when over sloped surfaces. For surfaces with 2 deg. slopes, knowledge of pointing angle of the beam's centroid to about 8 urad is needed to achieve 10 cm height accuracy. GLAS uses a stellar reference system (SRS) to determine the pointing angle of each laser firing relative to inertial space. The SRS uses a high precision star camera oriented toward local zenith and a gyroscope to determine the inertial orientation of the SRS optical bench. The far field pattern of each laser is measured pulse relative to the star camera with a laser reference system (LRS). Optically measuring each laser far field pattern relative to the orientation of the star camera and gyroscope permits the precise pointing angle of each laser pulse to be determined. GLAS will also determine the vertical distributions of clouds and aerosols by measuring the vertical profile of laser energy backscattered by the atmosphere at both 1064 and 532 nm. The 1064 nm measurements use the Si APD detector and profile the height and vertical structure of thicker clouds. The measurements at 532 nm use new highly sensitive photon counting, detectors, and measure the height distributions of very thin Clouds and aerosol layers. With averaging these can be used to determine the height of the planetary boundary layer. The instrument design and expected performance will be discussed.

Neutron/ γ-ray digital pulse shape discrimination with organic scintillators

NASA Astrophysics Data System (ADS)

Kaschuck, Y.; Esposito, B.

2005-10-01

Neutrons and γ-rays produce light pulses with different shapes when interacting with organic scintillators. This property is commonly used to distinguish between neutrons (n) and γ-rays ( γ) in mixed n/ γ fields as those encountered in radiation physics experiments. Although analog electronic pulse shape discrimination (PSD) modules have been successfully used for many years, they do not allow data reprocessing and are limited in count rate capability (typically up to 200 kHz). The performance of a n/ γ digital pulse shape discrimination (DPSD) system by means of a commercial 12-bit 200 MSamples/s transient recorder card is investigated here. Three organic scintillators have been studied: stilbene, NE213 and anthracene. The charge comparison method has been used to obtain simultaneous n/ γ discrimination and pulse height analysis. The importance of DPSD for high-intensity radiation field measurements and its advantages with respect to analog PSD are discussed. Based on post-experiment simulations with acquired data, the requirements for fast digitizers to provide DPSD with organic scintillators are also analyzed.

Cross-Shore Exchange on Natural Beaches

DTIC Science & Technology

2014-09-01

87   Figure 2.   Wave conditions measured by the ADCP in 13 m water depth of (a) root- mean-square wave height Hrms...horizontal velocity, Umean, measured in the reference level, ∑Tsig,pulse T3−hour ∑Tsig,pulse T3−hour xi (e) local water depth, h, and (f) local root...mean-square wave height normalized by the local water depth, Hrms/h, measured by ADCPin (blue) and ADCPout (red) during the 3HRLTs. Colored lines

Selection of optimal welding condition for GTA pulse welding in root-pass of V-groove butt joint

NASA Astrophysics Data System (ADS)

Yun, Seok-Chul; Kim, Jae-Woong

2010-12-01

In the manufacture of high-quality welds or pipeline, a full-penetration weld has to be made along the weld joint. Therefore, root-pass welding is very important, and its conditions have to be selected carefully. In this study, an experimental method for the selection of optimal welding conditions is proposed for gas tungsten arc (GTA) pulse welding in the root pass which is done along the V-grooved butt-weld joint. This method uses response surface analysis in which the width and height of back bead are chosen as quality variables of the weld. The overall desirability function, which is the combined desirability function for the two quality variables, is used as the objective function to obtain the optimal welding conditions. In our experiments, the target values of back bead width and height are 4 mm and zero, respectively, for a V-grooved butt-weld joint of a 7-mm-thick steel plate. The optimal welding conditions could determine the back bead profile (bead width and height) as 4.012 mm and 0.02 mm. From a series of welding tests, it was revealed that a uniform and full-penetration weld bead can be obtained by adopting the optimal welding conditions determined according to the proposed method.

SAMPLING OSCILLOSCOPE

DOEpatents

Sugarman, R.M.

1960-08-30

An oscilloscope is designed for displaying transient signal waveforms having random time and amplitude distributions. The oscilloscopc is a sampling device that selects for display a portion of only those waveforms having a particular range of amplitudes. For this purpose a pulse-height analyzer is provided to screen the pulses. A variable voltage-level shifter and a time-scale rampvoltage generator take the pulse height relative to the start of the waveform. The variable voltage shifter produces a voltage level raised one step for each sequential signal waveform to be sampled and this results in an unsmeared record of input signal waveforms. Appropriate delay devices permit each sample waveform to pass its peak amplitude before the circuit selects it for display.

Improved neutron-gamma discrimination for a {sup 6}Li-glass neutron detector using digital signal analysis methods

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

Wang, C. L., E-mail: wangc@ornl.gov; Riedel, R. A.

2016-01-15

A {sup 6}Li-glass scintillator (GS20) based neutron Anger camera was developed for time-of-flight single-crystal diffraction instruments at Spallation Neutron Source. Traditional Pulse-Height Analysis (PHA) for Neutron-Gamma Discrimination (NGD) resulted in the neutron-gamma efficiency ratio (defined as NGD ratio) on the order of 10{sup 4}. The NGD ratios of Anger cameras need to be improved for broader applications including neutron reflectometers. For this purpose, six digital signal analysis methods of individual waveforms acquired from photomultiplier tubes were proposed using (i) charge integration, (ii) pulse-amplitude histograms, (iii) power spectrum analysis combined with the maximum pulse-amplitude, (iv) two event parameters (a{sub 1}, b{submore » 0}) obtained from a Wiener filter, (v) an effective amplitude (m) obtained from an adaptive least-mean-square filter, and (vi) a cross-correlation coefficient between individual and reference waveforms. The NGD ratios are about 70 times those from the traditional PHA method. Our results indicate the NGD capabilities of neutron Anger cameras based on GS20 scintillators can be significantly improved with digital signal analysis methods.« less

Regression analysis and transfer function in estimating the parameters of central pulse waves from brachial pulse wave.

PubMed

Chai Rui; Li Si-Man; Xu Li-Sheng; Yao Yang; Hao Li-Ling

2017-07-01

This study mainly analyzed the parameters such as ascending branch slope (A_slope), dicrotic notch height (Hn), diastolic area (Ad) and systolic area (As) diastolic blood pressure (DBP), systolic blood pressure (SBP), pulse pressure (PP), subendocardial viability ratio (SEVR), waveform parameter (k), stroke volume (SV), cardiac output (CO) and peripheral resistance (RS) of central pulse wave invasively and non-invasively measured. These parameters extracted from the central pulse wave invasively measured were compared with the parameters measured from the brachial pulse waves by a regression model and a transfer function model. The accuracy of the parameters which were estimated by the regression model and the transfer function model was compared too. Our findings showed that in addition to the k value, the above parameters of the central pulse wave and the brachial pulse wave invasively measured had positive correlation. Both the regression model parameters including A_slope, DBP, SEVR and the transfer function model parameters had good consistency with the parameters invasively measured, and they had the same effect of consistency. The regression equations of the three parameters were expressed by Y'=a+bx. The SBP, PP, SV, CO of central pulse wave could be calculated through the regression model, but their accuracies were worse than that of transfer function model.

Tomographic analysis of neutron and gamma pulse shape distributions from liquid scintillation detectors at Joint European Torus.

PubMed

Giacomelli, L; Conroy, S; Gorini, G; Horton, L; Murari, A; Popovichev, S; Syme, D B

2014-02-01

The Joint European Torus (JET, Culham, UK) is the largest tokamak in the world devoted to nuclear fusion experiments of magnetic confined Deuterium (D)/Deuterium-Tritium (DT) plasmas. Neutrons produced in these plasmas are measured using various types of neutron detectors and spectrometers. Two of these instruments on JET make use of organic liquid scintillator detectors. The neutron emission profile monitor implements 19 liquid scintillation counters to detect the 2.45 MeV neutron emission from D plasmas. A new compact neutron spectrometer is operational at JET since 2010 to measure the neutron energy spectra from both D and DT plasmas. Liquid scintillation detectors are sensitive to both neutron and gamma radiation but give light responses of different decay time such that pulse shape discrimination techniques can be applied to identify the neutron contribution of interest from the data. The most common technique consists of integrating the radiation pulse shapes within different ranges of their rising and/or trailing edges. In this article, a step forward in this type of analysis is presented. The method applies a tomographic analysis of the 3-dimensional neutron and gamma pulse shape and pulse height distribution data obtained from liquid scintillation detectors such that n/γ discrimination can be improved to lower energies and additional information can be gained on neutron contributions to the gamma events and vice versa.

Effect of intense pulsed light on immature burn scars: A clinical study

PubMed Central

Sarkar, Arindam; Dewangan, Yatindra Kumar; Bain, Jayanta; Rakshit, Pritha; Dhruw, Krishnanand; Basu, Sandip Kanti; Saha, Jayanta Kumar; Majumdar, Bijay Kumar

2014-01-01

Introduction: As intense pulsed light (IPL) is widely used to treat cutaneous vascular malformations and also used as non-ablative skin rejunuvation to remodel the skin collagen. A study has been undertaken to gauze the effect of IPL on immature burn scars with regard to vascularity, pliability and height. Materials and Methods: This study was conducted between June 2013 and May 2014, among patients with immature burn scars that healed conservatively within 2 months. Photographic evidence of appearance of scars and grading and rating was done with Vancouver Scar Scale parameters. Ratings were done for both case and control scar after the completion of four IPL treatment sessions and were compared. Results: Out of the 19 cases, vascularity, pliability and height improved significantly (P < 0.05) in 13, 14 and 11 scars respectively following IPL treatment. Conclusions: Intense pulsed light was well-tolerated by patients, caused good improvement in terms of vascularity, pliability, and height of immature burn scar. PMID:25593424

In-Service Monitoring of Steam Pipe Systems at High Temperatures

NASA Technical Reports Server (NTRS)

Bar-Cohen, Yoseph; Lih, Shyh-Shiuh; Badescu, Mircea; Bao, Xiaoqi; Sherrit, Stewart; Scott, James S.; Blosiu, Julian O.; Widholm, Scott E.

2011-01-01

An effective, in-service health monitoring system is needed to track water condensation in real time through the walls of steam pipes. The system is required to measure the height of the condensed water from outside the pipe, while operating at temperatures that are as high as 250 C. The system needs to account for the effects of water flow and cavitation. In addition, it is desired that the system does not require perforating the pipes and thereby reducing the structural integrity. Generally, steam pipes are used as part of the district heating system carrying steam from central power stations under the streets to heat, cool, or supply power to high-rise buildings and businesses. This system uses ultrasonic waves in pulse-echo and acquires reflected signal data. Via autocorrelation, it determines the water height while eliminating the effect of noise and multiple reflections from the wall of the pipe. The system performs nondestructive monitoring through the walls of steam pipes, and automatically measures the height of condensed water while operating at the high-temperature conditions of 250 C. For this purpose, the ultrasonic pulse-echo method is used where the time-of-flight of the wave reflections inside the water are measured, and it is multiplied by the wave velocity to determine the height. The pulse-echo test consists of emitting ultrasonic wave pulses from a piezoelectric transducer and receiving the reflections from the top and bottom of the condensed water. A single transducer is used as a transmitter as well as the receiver of the ultrasonic waves. To obtain high resolution, a broadband transducer is used and the frequency can be in the range of 2.25 to 10 MHz, providing sharp pulses in the time domain allowing for higher resolution in identifying the individual reflections.

Pulse-Shape Discrimination of Alpha Particles of Different Specific Energy-Loss With Parallel-Plate Avalanche Counters

NASA Astrophysics Data System (ADS)

Nakhostin, M.; Baba, M.

2014-06-01

Parallel-plate avalanche counters have long been recognized as timing detectors for heavily ionizing particles. However, these detectors suffer from a poor pulse-height resolution which limits their capability to discriminate between different ionizing particles. In this paper, a new approach for discriminating between charged particles of different specific energy-loss with avalanche counters is demonstrated. We show that the effect of the self-induced space-charge in parallel-plate avalanche counters leads to a strong correlation between the shape of output current pulses and the amount of primary ionization created by the incident charged particles. The correlation is then exploited for the discrimination of charged particles with different energy-losses in the detector. The experimental results obtained with α-particles from an 241Am α-source demonstrate a discrimination capability far beyond that achievable with the standard pulse-height discrimination method.

Evaluation of the health status of six volunteers from the Mars 500 project using pulse analysis.

PubMed

Shi, Hong-Zhi; Fan, Quan-Chun; Gao, Jian-Yi; Liu, Jun-Lian; Bai, Gui-E; Mi, Tao; Zhao, Shuang; Liu, Yu; Xu, Dong; Guo, Zhi-Feng; Li, Yong-Zhi

2017-08-01

To comprehensively evaluate the health status of 6 volunteers from the Mars 500 Project through analyzing their pulse graphs and determining the changes in cardiovascular function, degree of fatigue and autonomic nervous function. Six volunteers were recruited; all were male aged 26-38 years (average 31.83±4.96 years). Characteristic parameters reflflecting the status of cardiovascular functions were extracted, which included left ventricular contraction, vascular elasticity and peripheral resistance. The degree of fatigue was determined depending on the difference between the calendar age and biological age, which was calculated through the analysis of blood pressure value and characteristic parameters. Based on the values of pulse height variation and pulse time variation on a 30-s pulse graph, autonomic nervous function was evaluated. All parameters examined were marked on an equilateral polygon to form an irregular polygon of the actual fifigure, then health status was evaluated based on the coverage area of the actual fifigure. The results demonstrated: (1) volunteers developed weakened pulse power, increased vascular tension and peripheral resistance, and slight decreased ventricular systolic function; (2) the degree of fatigue was basically mild or moderate; and (3) autonomic nervous function was excited but generally balanced. These volunteers were in the state of sub-health. According to Chinese medicine theories, such symptoms are mainly caused by the weakening of healthy qi, Gan (Liver) failing in free coursing, and disharmony between Gan and Wei (Stomach), which manifests as a weak and string-like pulse.

Effects of low-dose cranial radiation on growth hormone secretory dynamics and hypothalamic-pituitary function

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

Costin, G.

1988-08-01

Spontaneous growth hormone (GH) secretory dynamics and hypothalamic-pituitary function were studied in 16 long-term survivors of acute lymphoblastic leukemia who were aged 9 to 15 1/2 years and had been treated with prophylactic central nervous system radiation and combined chemotherapy. At the time of study, the mean height was -1.5 SD score below the mean, less than genetic potential, and significantly less than the mean pretreatment height of -0.25 SD score. Height velocity was subnormal for age and sexual stage in all patients. Two patients had compensated hypothyroidism, and four had evidence of gonadal failure. In 11 patients, the peakmore » GH level after two provocative tests was below 10 micrograms/L, which was consistent with GH deficiency. In ten of 13 patients tested, spontaneous GH secretion determined by a 24-hour GH concentration (GHC), GH pulse amplitude, frequency of GH pulses greater than or equal to 5 micrograms/L, and GH peak during wake and sleep hours was significantly less than in normal height controls. Although in three pubertal patients the 24-hour GHC was within normal limits, the GHC during sleep hours, GH pulse amplitude during 24 hours and sleep hours, and peak GH during wake hours were significantly less than in normal height controls. In all pubertal and in two of the prepubertal patients, the somatomedin C (SmC) level was significantly less than in controls. The 24-hour GHC correlated well with the GHC during sleep, peak-stimulated GH level, gonadal steroid level, and the SmC level, but not with height velocity, dose of radiation, or age at radiation. A significant increase in height velocity and the SmC level was noted in all patients treated with GH. These results indicate that GH deficiency occurs after 18 to 24 Gy of cranial radiation and that the puberty-associated growth spurt may mask the decline in height velocity owing to GH deficiency.« less

Analysis of laser altimeter waveforms for forested ecosystems of Central Florida

NASA Astrophysics Data System (ADS)

Weishampel, John F.; Harding, David J.; Boutet, Jeffry C., Jr.; Drake, Jason B.

1997-07-01

An experimental profiling airborne laser altimeter system developed at NASA's Goddard Space Flight Center was used to acquire vertical canopy data from several ecosystem types from The Nature Conservancy's Disney Wilderness Preserve, near Kissimmee, Florida. This laser altimeter, besides providing submeter accuracy of tree height, captures a profile of data which relates to the magnitude of reflectivity of the laser pulse as it penetrates different elevations of the forest canopy. This complete time varying amplitude of the return signal of the laser pulse, between the first (i.e., the canopy top) and last (i.e., the ground) returns, yields a waveform which is related to canopy architecture, specifically the nadir-projected vertical distribution of the surface of canopy components (i.e., foliage, twigs, and branches). Selected profile returns from representative covertypes (e.g., pine flatwoods, bayhead, and cypress wetland) were compared with ground truthed forest composition (i.e., species and size class distribution) and structural (i.e., canopy height, canopy closure, crown depth) measures to help understand how these properties contribute to variation in the altimeter waveform.

Insight into the dicrotic notch in photoplethysmographic pulses from the finger tip of young adults.

PubMed

Shi, P; Hu, S; Zhu, Y; Zheng, J; Qiu, Y; Cheang, P Y S

2009-01-01

This study aims to investigate arterial stiffness in selected young adults by non-invasively determining the characteristics of the photoplethysmographic dicrotic notch. A total of 15 volunteers participated in this study, divided into four groups by age and gender. Contour analysis was applied to analyse the photoplethysmographic dicrotic notch, including time-related and height-related parameters. The height of reflected wave, mirrored by the notch relative amplitude (NRA), was found to be significantly larger in the older group compared to the younger group (p = 0.016). The timing of the reflected wave, measured by three parameters, i.e. notch index (NI), notch latency (NL) and peak-to-notch latency (PTNL), significantly increased in the female group compared to the male group (all p < 0.02). The results confirm that arterial stiffness occurs in young adults, and demonstrate that a difference of arterial stiffness exists between young male and female. This study indicates that examining the characteristic notch of the PPG pulse could help in identifying differences of vascular activities.

Aerosol Measurements by the Globally Distributed Micro Pulse Lidar Network

NASA Technical Reports Server (NTRS)

Spinhirne, James; Welton, Judd; Campbell, James; Berkoff, Tim; Starr, David (Technical Monitor)

2001-01-01

Full time measurements of the vertical distribution of aerosol are now being acquired at a number of globally distributed MP (micro pulse) lidar sites. The MP lidar systems provide full time profiling of all significant cloud and aerosol to the limit of signal attenuation from compact, eye safe instruments. There are currently eight sites in operation and over a dozen planned. At all sited there are also passive aerosol and radiation measurements supporting the lidar data. Four of the installations are at Atmospheric Radiation Measurement program sites. The network operation includes instrument operation and calibration and the processing of aerosol measurements with standard retrievals and data products from the network sites. Data products include optical thickness and extinction cross section profiles. Application of data is to supplement satellite aerosol measurements and to provide a climatology of the height distribution of aerosol. The height distribution of aerosol is important for aerosol transport and the direct scattering and absorption of shortwave radiation in the atmosphere. Current satellite and other data already provide a great amount of information on aerosol distribution, but no passive technique can adequately resolve the height profile of aerosol. The Geoscience Laser Altimeter System (GLAS) is an orbital lidar to be launched in early 2002. GLAS will provide global measurements of the height distribution of aerosol. The MP lidar network will provide ground truth and analysis support for GLAS and other NASA Earth Observing System data. The instruments, sites, calibration procedures and standard data product algorithms for the MPL network will be described.

The relationship between weight, height and body mass index with hemodynamic parameters is not same in patients with and without chronic kidney disease.

PubMed

Afsar, Baris; Elsurer, Rengin; Soypacaci, Zeki; Kanbay, Mehmet

2016-02-01

Although anthropometric measurements are related with clinical outcomes; these relationships are not universal and differ in some disease states such as in chronic kidney disease (CKD). The current study was aimed to analyze the relationship between height, weight and BMI with hemodynamic and arterial stiffness parameters both in normal and CKD patients separately. This cross-sectional study included 381 patients with (N 226) and without CKD (N 155) with hypertension. Routine laboratory and 24-h urine collection were performed. Augmentation index (Aix) which is the ratio of augmentation pressure to pulse pressure was calculated from the blood pressure waveform after adjusted heart rate at 75 [Aix@75 (%)]. Pulse wave velocity (PWV) is a simple measure of the time taken by the pressure wave to travel over a specific distance. Both [Aix@75 (%)] and PWV which are measures of arterial stiffness were measured by validated oscillometric methods using mobil-O-Graph device. In patients without CKD, height is inversely correlated with [Aix@75 (%)]. Additionally, weight and BMI were positively associated with PWV in multivariate analysis. However, in patients with CKD, weight and BMI were inversely and independently related with PWV. In CKD patients, as weight and BMI increased stiffness parameters such as Aix@75 (%) and PWV decreased. While BMI and weight are positively associated with arterial stiffness in normal patients, this association is negative in patients with CKD. In conclusion, height, weight and BMI relationship with hemodynamic and arterial stiffness parameters differs in patients with and without CKD.

High-rate dead-time corrections in a general purpose digital pulse processing system

PubMed Central

Abbene, Leonardo; Gerardi, Gaetano

2015-01-01

Dead-time losses are well recognized and studied drawbacks in counting and spectroscopic systems. In this work the abilities on dead-time correction of a real-time digital pulse processing (DPP) system for high-rate high-resolution radiation measurements are presented. The DPP system, through a fast and slow analysis of the output waveform from radiation detectors, is able to perform multi-parameter analysis (arrival time, pulse width, pulse height, pulse shape, etc.) at high input counting rates (ICRs), allowing accurate counting loss corrections even for variable or transient radiations. The fast analysis is used to obtain both the ICR and energy spectra with high throughput, while the slow analysis is used to obtain high-resolution energy spectra. A complete characterization of the counting capabilities, through both theoretical and experimental approaches, was performed. The dead-time modeling, the throughput curves, the experimental time-interval distributions (TIDs) and the counting uncertainty of the recorded events of both the fast and the slow channels, measured with a planar CdTe (cadmium telluride) detector, will be presented. The throughput formula of a series of two types of dead-times is also derived. The results of dead-time corrections, performed through different methods, will be reported and discussed, pointing out the error on ICR estimation and the simplicity of the procedure. Accurate ICR estimations (nonlinearity < 0.5%) were performed by using the time widths and the TIDs (using 10 ns time bin width) of the detected pulses up to 2.2 Mcps. The digital system allows, after a simple parameter setting, different and sophisticated procedures for dead-time correction, traditionally implemented in complex/dedicated systems and time-consuming set-ups. PMID:26289270

Determination of cadmium in sewage sludge by differential pulse anodic stripping voltammetry.

PubMed

Pacer, R A; Scott Ellis, C K; Peng, R

1999-07-12

A procedure was developed for the determination of cadmium in sewage sludge by differential pulse anodic stripping voltammetry. A sodium peroxide fusion carried out in zirconium crucibles was found to give satisfactory results, based on analysis of standard reference materials. Samples collected from the municipal sludge lagoon in Fort Wayne, Indiana were found to have cadmium abundances ranging from 120 to 250 ppm, with most samples falling in the 120 to 170 ppm range. Interference from zinc is easily eliminated by carrying out the deposition step at -0.95 V vs. Ag/AgCl. Lead-to-cadmium ratios as high as 50:1 (ppm basis) have no effect on the height of the cadmium peak.

Chinese-English Rocketry Dictionary. Volume 2

DTIC Science & Technology

1978-02-01

dissection; dissect jiesan • break up; peel off; disperse; dismiss; dissolve jieshi explan.ation; explain; interpretation; exposition jieshi chengxu...integral pulse-height 20fenbu distribution maichong baoxien f , jp pulse envelope 21 maichong banna I 4 I 1 impulse coding 22 maichong bianrs

Systematic studies of small scintillators for new sampling calorimeter

NASA Astrophysics Data System (ADS)

Jacosalem, E. P.; Iba, S.; Nakajima, N.; Ono, H.; Sanchez, A. L. C.; Bacala, A. M.; Miyata, H.

2007-12-01

A new sampling calorimeter using very thin scintillators and the multi-pixel photon counter (MPPC) has been proposed to produce better position resolution for the international linear collider (ILC) experiment. As part of this R&D study, small plastic scintillators of different sizes, thickness and wrapping reflectors are systematically studied. The scintillation light due to beta rays from a collimated ^{90}Sr source are collected from the scintillator by wavelength-shifting (WLS) fiber and converted into electrical signals at the PMT. The wrapped scintillator that gives the best light yield is determined by comparing the measured pulse height of each 10 × 40 × 2 mm strip scintillator covered with 3M reflective mirror film, teflon, white paint, black tape, gold, aluminum and white paint+teflon. The pulse height dependence on position, length and thickness of the 3M reflective mirror film and teflon wrapped scintillators are measured. Results show that the 3M radiant mirror film-wrapped scintillator has the greatest light yield with an average of 9.2 photoelectrons. It is observed that light yield slightly increases with scintillator length, but increases to about 100% when WLS fiber diameter is increased from 1.0 mm to 1.6 mm. The position dependence measurement along the strip scintillator showed the uniformity of light transmission from the sensor to the PMT. A dip across the strip is observed which is 40% of the maximum pulse height. The block type scintillator pulse height, on the other hand, is found to be almost proportional to scintillator thickness.

Improved neutron-gamma discrimination for a 6Li-glass neutron detector using digital signal analysis methods

DOE PAGES

Wang, Cai -Lin; Riedel, Richard A.

2016-01-14

A 6Li-glass scintillator (GS20) based neutron Anger camera was developed for time-of-flight single-crystal diffraction instruments at SNS. Traditional pulse-height analysis (PHA) for neutron-gamma discrimination (NGD) resulted in the neutron-gamma efficiency ratio (defined as NGD ratio) on the order of 10 4. The NGD ratios of Anger cameras need to be improved for broader applications including neutron reflectometers. For this purpose, five digital signal analysis methods of individual waveforms from PMTs were proposed using: i). pulse-amplitude histogram; ii). power spectrum analysis combined with the maximum pulse amplitude; iii). two event parameters (a 1, b 0) obtained from Wiener filter; iv). anmore » effective amplitude (m) obtained from an adaptive least-mean-square (LMS) filter; and v). a cross-correlation (CC) coefficient between an individual waveform and a reference. The NGD ratios can be 1-102 times those from traditional PHA method. A brighter scintillator GS2 has better NGD ratio than GS20, but lower neutron detection efficiency. The ultimate NGD ratio is related to the ambient, high-energy background events. Moreover, our results indicate the NGD capability of neutron Anger cameras can be improved using digital signal analysis methods and brighter neutron scintillators.« less

Particle identification using digital pulse shape discrimination in a nTD silicon detector with a 1 GHz sampling digitizer

NASA Astrophysics Data System (ADS)

Mahata, K.; Shrivastava, A.; Gore, J. A.; Pandit, S. K.; Parkar, V. V.; Ramachandran, K.; Kumar, A.; Gupta, S.; Patale, P.

2018-06-01

In beam test experiments have been carried out for particle identification using digital pulse shape analysis in a 500 μm thick Neutron Transmutation Doped (nTD) silicon detector with an indigenously developed FPGA based 12 bit resolution, 1 GHz sampling digitizer. The nTD Si detector was used in a low-field injection setup to detect light heavy-ions produced in reactions of ∼ 5 MeV/A 7Li and 12C beams on different targets. Pulse height, rise time and current maximum have been obtained from the digitized charge output of a high bandwidth charge and current sensitive pre-amplifier. Good isotopic separation have been achieved using only the digitized charge output in case of light heavy-ions. The setup can be used for charged particle spectroscopy in nuclear reactions involving light heavy-ions around the Coulomb barrier energies.

A microcomputer-based whole-body counter for personnel routine monitoring.

PubMed

Chou, H P; Tsai, T M; Lan, C Y

1993-05-01

The paper describes a cost-effective NaI(Tl) whole-body counter developed for routine examinations of worker intakes at an isotope production facility. Signal processing, data analysis and system operation are microcomputer-controlled for minimum human interactions. The pulse height analyzer is developed as an microcomputer add-on card for easy manipulation. The scheme for radionuclide analysis is aimed for fast running according to a knowledge base established from background samples and phantom experiments in conjunction with a multivariate regression analysis. Long-term stability and calibration with standards and in vivo measurements are reported.

Pulse-to-pulse correlation in satellite radar altimeters. [for ocean wave height measurement

NASA Technical Reports Server (NTRS)

Walsh, E. J.

1982-01-01

Pulse-to-pulse correlation in satellite radar altimeters is examined to determine if range jitter in future altimeters could be reduced by increasing the pulse repetition frequency (PRF). Data from the Skylab radar altimeter is analyzed and compared with rules of thumb and the results of a Monte Carlo simulation. Altimeter range tracker configurations are reviewed and a simple curve is developed for the PRF below which decorrelation is assured. An adaptive PRF for future altimeters is recommended to conserve mission power while optimizing data collection during high-sea states.

MULTI-CHANNEL ELECTRIC PULSE HEIGHT ANALYZER

DOEpatents

Gallagher, J.D. et al.

1960-11-22

An apparatus is given for converting binary information into coded decimal form comprising means, in combination with a binary adder, a live memory and a source of bigit pulses, for synchronizing the bigit pulses and the adder output pulses; a source of digit pulses synchronized with every fourth bigit pulse; means for generating a conversion pulse in response to the time coincidence of the adder output pulse and a digit pulse: means having a delay equal to two bigit pulse periods coupling the adder output with the memory; means for promptly impressing said conversion pulse on the input of said memory: and means having a delay equal to one bigit pulse period for again impressing the conversion pulse on the input of the memory whereby a fourth bigit adder pulse results in the insertion into the memory of second, third and fourth bigits.

Pulse height tests of a large diameter fast LaBr₃:Ce scintillation detector.

PubMed

Naqvi, A A; Khiari, F Z; Maslehuddin, M; Gondal, M A; Al-Amoudi, O S B; Ukashat, M S; Ilyas, A M; Liadi, F A; Isab, A A; Khateeb-ur Rehman; Raashid, M; Dastageer, M A

2015-10-01

The pulse height response of a large diameter fast 100 mm × 100 mm LaBr3:Ce detector was measured for 0.1-10 MeV gamma-rays. The detector has a claimed time resolution of 608 ps for 511 keV gamma rays, but has relatively poor energy resolution due to the characteristics of its fast photomultiplier. The detector pulse height response was measured for gamma rays from cobalt, cesium, and bismuth radioisotope sources as well as prompt gamma rays from thermal neutron capture in water samples contaminated with mercury (3.1 wt%), boron (2.5 wt%), cadmium (0.25 wt%), chromium (52 wt%), and nickel (22 wt%) compounds. The energy resolution of the detector was determined from full width at half maximum (FWHM) of element-characteristic gamma ray peaks in the pulse height spectrum associated with the element present in the contaminated water sample. The measured energy resolution of the 100 mm × 100 mm detector varies from 12.7±0.2% to 1.9±0.1% for 0.1 to 10 MeV gamma rays, respectively. The graph showing the energy resolution ΔE/E(%) versus 1/√Eγ was fitted with a linear function to study the detector light collection from the slope of the curve. The slope of the present 100 mm × 100 mm detector is almost twice as large as the slope of a similar curve of previously published data for a 89 mm × 203 mm LaBr3:Ce detector. This indicates almost two times poorer light collection in the 100 mm × 100 mm detector as compared to the other detector. Copyright © 2015 Elsevier Ltd. All rights reserved.

Changes in metal properties after thermal and electric impulse processing

NASA Astrophysics Data System (ADS)

Shaburova, N. A.

2015-04-01

The results of the experiments on processing metal melts by powerful electromagnetic impulses are given. The generator used in the experiments has the following characteristics: pulse height - 10KV, duration - 1ns, leading edge - 0.1ns, repetition rate - 1KHz, the output - 100KWt. The duration of the processing is 10-15min. The comparative analysis of the processed and unprocessed samples results in the changes of structure, increase of density, solidity, plasticity and resilience of cast metal. The result analysis of different external physical processing methods on alloys shows full agreement with the results of the ultrasonic processing of metals. The hypothesis of ultrasonic shock wave formation at the pulse front was adopted as the main mechanism of the electromagnetic impulse impact on alloys. The theoretical part of the research describes the transformation process of electromagnetic impulses into acoustic ones.

Position sensitive detection of nuclear radiation mediated by non equilibrium phonons at low temperatures

NASA Astrophysics Data System (ADS)

Pröbst, F.; Peterreins, Th.; Feilitzsch, F. v.; Kraus, H.

1990-03-01

Many experiments in nuclear and particle physics would benefit from the development of a device capable of detecting non-ionizing events with a low energy threshold. In this context, we report on experimental tests of a detector based on the registration of nonequilibrium phonons. The device is composed of a silicon single crystal (size: 20×10×3 mm 3) and of an array of superconducting tunnel junctions evaporated onto the surface of the crystal. The junctions serve as sensors for phonons created by absorption of nuclear radiation in the crystal. We show how pulse height analysis and the investigation of time differences between correlated pulses in different junctions can be used to obtain information about the point of absorption.

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

Giacomelli, L.; Department of Physics, Università degli Studi di Milano-Bicocca, Milano; Conroy, S.

The Joint European Torus (JET, Culham, UK) is the largest tokamak in the world devoted to nuclear fusion experiments of magnetic confined Deuterium (D)/Deuterium-Tritium (DT) plasmas. Neutrons produced in these plasmas are measured using various types of neutron detectors and spectrometers. Two of these instruments on JET make use of organic liquid scintillator detectors. The neutron emission profile monitor implements 19 liquid scintillation counters to detect the 2.45 MeV neutron emission from D plasmas. A new compact neutron spectrometer is operational at JET since 2010 to measure the neutron energy spectra from both D and DT plasmas. Liquid scintillation detectorsmore » are sensitive to both neutron and gamma radiation but give light responses of different decay time such that pulse shape discrimination techniques can be applied to identify the neutron contribution of interest from the data. The most common technique consists of integrating the radiation pulse shapes within different ranges of their rising and/or trailing edges. In this article, a step forward in this type of analysis is presented. The method applies a tomographic analysis of the 3-dimensional neutron and gamma pulse shape and pulse height distribution data obtained from liquid scintillation detectors such that n/γ discrimination can be improved to lower energies and additional information can be gained on neutron contributions to the gamma events and vice versa.« less

Determination of mean surface position and sea state from the radar return of a short-pulse satellite altimeter

NASA Technical Reports Server (NTRS)

Barrick, D. E.

1972-01-01

Using the specular point theory of scatter from a very rough surface, the average backscatter cross section per unit area per radar cell width is derived for a cell located at a given height above the mean sea surface. This result is then applied to predict the average radar cross section observed by a short-pulse altimeter as a function of time for two modes of operation: pulse-limited and beam-limited configurations. For a pulse-limited satellite altimeter, a family of curves is calculated showing the distortion of the leading edge of the receiver output signal as a function of sea state (i.e., wind speed). A signal processing scheme is discussed that permits an accurate determination of the mean surface position--even in high seas--and, as a by-product, the estimation of the significant seawave height (or wind speed above the surface). Comparison of these analytical results with experimental data for both pulse-limited and beam-limited operation lends credence to the model. Such a model should aid in the design of short-pulse altimeters for accurate determination of the geoid over the oceans, as well as for the use of such altimeters for orbital sea-state monitoring.

Investigation of FPGA-Based Real-Time Adaptive Digital Pulse Shaping for High-Count-Rate Applications

NASA Astrophysics Data System (ADS)

Saxena, Shefali; Hawari, Ayman I.

2017-07-01

Digital signal processing techniques have been widely used in radiation spectrometry to provide improved stability and performance with compact physical size over the traditional analog signal processing. In this paper, field-programmable gate array (FPGA)-based adaptive digital pulse shaping techniques are investigated for real-time signal processing. National Instruments (NI) NI 5761 14-bit, 250-MS/s adaptor module is used for digitizing high-purity germanium (HPGe) detector's preamplifier pulses. Digital pulse processing algorithms are implemented on the NI PXIe-7975R reconfigurable FPGA (Kintex-7) using the LabVIEW FPGA module. Based on the time separation between successive input pulses, the adaptive shaping algorithm selects the optimum shaping parameters (rise time and flattop time of trapezoid-shaping filter) for each incoming signal. A digital Sallen-Key low-pass filter is implemented to enhance signal-to-noise ratio and reduce baseline drifting in trapezoid shaping. A recursive trapezoid-shaping filter algorithm is employed for pole-zero compensation of exponentially decayed (with two-decay constants) preamplifier pulses of an HPGe detector. It allows extraction of pulse height information at the beginning of each pulse, thereby reducing the pulse pileup and increasing throughput. The algorithms for RC-CR2 timing filter, baseline restoration, pile-up rejection, and pulse height determination are digitally implemented for radiation spectroscopy. Traditionally, at high-count-rate conditions, a shorter shaping time is preferred to achieve high throughput, which deteriorates energy resolution. In this paper, experimental results are presented for varying count-rate and pulse shaping conditions. Using adaptive shaping, increased throughput is accepted while preserving the energy resolution observed using the longer shaping times.

Geoscience Laser Altimeter System (GLAS) for the ICESat Mission

NASA Technical Reports Server (NTRS)

Abshire, James B.; Sun, Xiaoli; Ketchum, Eleanor A.; Millar, Pamela S.; Riris, Haris

2002-01-01

The Geoscience Laser Altimeter System (GLAS) is a new generation lidar and is the primary science payload for NASA's ICESat Mission. The GLAS design combines a 10 cm precision surface lidar with a sensitive dual wavelength cloud and aerosol lidar. GLAS will precisely measure the heights of the Earth's polar ice sheets, establish a grid of accurate height profiles of the Earth's land topography, and profile the vertical distribution of clouds and aerosols on a global scale. GLAS will be integrated onto a small spacecraft built by Ball Aerospace, and will be launched into a polar orbit with a 590-630 km altitude at an inclination of 94 degrees. ICESat is is currently planned to launch in winter 2002/03 and GLAS is designed to operate continuously in space for a minimum of 3 years. GLAS will measure the vertical distance from orbit to the Earth's surface with pulses from a ND:YAG laser at a 40 Hz rate. Each 6 nsec wide 1064 nm laser pulse is used to produce a single range measurement. On the surface, the laser footprints have 66 m diameter and approx. 170 m center-center spacings. The GLAS receiver uses a I m diameter telescope to detect laser backscatter and a Si APD to detect the 1064 nm signals. The detector's output is sampled by a digital ranging receiver, which records each transmitted pulse and surface echo waveform with 1 nsec (15 cm) resolution. Each echo pulse is digitized and is reported to ground with a record length of from 200 to 544 samples, depending on the spacecraft's location . The GLAS location and epoch times are measured by a precision GPS receiver carried on the ICESat spacecraft. Initial processing of the echo waveforms within GLAS permits discrimination between cloud and surface echoes for selecting appropriate waveform samples. This selection is guided by an on-board DEM which is used to set the boundaries for the echo pulse search algorithm. Subsequent ground-based echo pulse analysis, along with GPS-based clock frequency estimates, permit final determination of the range to the surface, degree of pulse spreading, and vertical distribution of any vegetation illuminated by the laser. Accurate knowledge of the laser beam's pointing angle is needed to prevent height biases when measuring over tilted surfaces, such as near the boundaries of ice sheets. For surfaces with 2 deg. slopes, knowledge of pointing angle of the beam's centroid angle to better than 10 urad is needed. GLAS uses a stellar reference system (SRS) to measure the pointing angle of each laser firing relative to inertial space. The SRS uses a high precision star camera oriented toward local zenith and a gyroscope to determine the inertial orientation of the SRS optical bench. The far field pattern of each laser is measured pulse relative to the star camera with a laser reference system (LRS). GLAS will also measure the vertical distributions of clouds and aerosols by recording the vertical profiles of laser pulse backscatter at both 1064 and 532 nm. The 1064 rim measurements use the Si APD detector and will be used to measure the height and echo pulse shape from thicker clouds. The lidar receiver at 532 nm uses a narrow bandwidth etalon filter and highly sensitive photon counting detectors. The 532 nm backscatter profiles will be used to measure the vertical extent of thinner clouds and the atmospheric boundary layer. The GLAS instrument component development is complete and the instrument is undergoing final testing and qualification at NASA-Goddard. The GLAS "as-built" characteristics and its expected measurement performance will be discussed.

Analysis of airborne radiometric data. Volume 3. Topical reports

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

Reed, J.H.; Shreve, D.C.; Sperling, M.

1978-05-01

This volume consists of four topical reports: a general discussion of the philosophy of unfolding spectra with continuum and discrete components, a mathematical treatment of the effects of various physical parameters on the uncollided gamma-ray spectrum at aircraft elevations, a discussion of the application of the unfolding code MAZNAI to airborne data, and a discussion of the effects of the nonlinear relationship between energy deposited and pulse height in NaI(T1) detectors.

Radiation imaging apparatus

DOEpatents

Anger, Hal O.; Martin, Donn C.; Lampton, Michael L.

1983-01-01

A radiation imaging system using a charge multiplier and a position sensitive anode in the form of periodically arranged sets of interconnected anode regions for detecting the position of the centroid of a charge cloud arriving thereat from the charge multiplier. Various forms of improved position sensitive anodes having single plane electrode connections are disclosed. Various analog and digital signal processing systems are disclosed, including systems which use the fast response of microchannel plates, anodes and preamps to perform scintillation pulse height analysis digitally.

Implications of Upwells as Hydrodynamic Jets in a Pulse Jet Mixed System

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

Pease, Leonard F.; Bamberger, Judith A.; Minette, Michael J.

2015-08-01

This report evaluates the physics of the upwell flow in pulse jet mixed systems in the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Although the initial downward flow and radial flow from pulse jet mixers (PJMs) has been analyzed in some detail, the upwells have received considerably less attention despite having significant implications for vessel mixing. Do the upwells behave like jets? How do the upwells scale? When will the central upwell breakthrough? What proportion of the vessel is blended by the upwells themselves? Indeed, how the physics of the central upwell is affected by multiple PJMs (e.g., sixmore » in the proposed mixing vessels), non-Newtonian rheology, and significant multicomponent solids loadings remain unexplored. The central upwell must satisfy several criteria to be considered a free jet. First, it must travel for several diameters in a nearly constant direction. Second, its velocity must decay with the inverse of elevation. Third, it should have an approximately Gaussian profile. Fourth, the influence of surface or body forces must be negligible. A combination of historical data in a 12.75 ft test vessel, newly analyzed data from the 8 ft test vessel, and conservation of momentum arguments derived specifically for PJM operating conditions demonstrate that the central upwell satisfies these criteria where vigorous breakthrough is achieved. An essential feature of scaling from one vessel to the next is the requirement that the underlying physics does not change adversely. One may have confidence in scaling if (1) correlations and formulas capture the relevant physics; (2) the underlying physics does not change from the conditions under which it was developed to the conditions of interest; (3) all factors relevant to scaling have been incorporated, including flow, material, and geometric considerations; and (4) the uncertainty in the relationships is sufficiently narrow to meet required specifications. Although the central upwell satisfies these criteria when vigorous breakthrough is achieved, not all available data follow the free jet profile for the central upwell, particularly at lower nozzle velocities. Alternative flow regimes are considered and new models for cloud height, “cavern height,” and the rate of jet penetration (jet celerity) are benchmarked against data to anchor scaling analyses. This analytical modeling effort to provide a technical basis for scaling PJM mixed vessels has significant implications for vessel mixing, because jet physics underlies “cavern” height, cloud height, and the volume of mixing considerations. A new four-parameter cloud height model compares favorably to experimental results. This model is predictive of breakthrough in 8 ft vessel tests with the two-part simulant. Analysis of the upwell in the presence of yield stresses finds evidence of expanding turbulent jets, confined turbulent jets, and confined laminar flows. For each, the critical elevation at which jet momentum depletes is predicted, which compare favorably to experimental cavern height data. Partially coupled momentum and energy balances suggest that these are limiting cases of a gradual transition from a turbulent expanding flow to a confined laminar flow. This analysis of the central upwell alone lays essential groundwork for complete analysis of mode three mixing (i.e., breakthrough with slow peripheral mixing). Consideration of jet celerity shows that the rate of jet penetration is a governing consideration in breakthrough to the surface. Estimates of the volume of mixing are presented. This analysis shows that flow along the vessel wall is sluggish such that the central upwell governs the volume of mixing. This analysis of the central upwell alone lays essential groundwork for complete analysis of mode three mixing and estimates of hydrogen release rates from first principles.« less

PARALYZER FOR PULSE HEIGHT DISTRIBUTION ANALYZER

DOEpatents

Fairstein, E.

1960-01-19

A paralyzer circuit is described for use with a pulseheight distribution analyzer to prevent the analyzer from counting overlapping pulses where they would serve to provide a false indication. The paralyzer circuit comprises a pair of cathode-coupled amplifiers for amplifying pulses of opposite polarity. Diodes are provided having their anodes coupled to the separate outputs of the amplifiers to produce only positive signals, and a trigger circuit is coupled to the diodes ior operation by input pulses of either polarity from the amplifiers. A delay network couples the output of the trigger circuit for delaying the pulses.

A near-infrared SETI experiment: commissioning, data analysis, and performance results

NASA Astrophysics Data System (ADS)

Maire, Jérôme; Wright, Shelley A.; Dorval, Patrick; Drake, Frank D.; Duenas, Andres; Isaacson, Howard; Marcy, Geoffrey W.; Siemion, Andrew; Stone, Remington P. S.; Tallis, Melisa; Treffers, Richard R.; Werthimer, Dan

2016-08-01

Over the last two decades, Optical Search for Extra-Terrestrial Intelligence experiments have been conducted to search for either continuous or pulsed visible-light laser beacons that could be used for interstellar communication or energy transmission. Near-infrared offers a compelling window for signal transmission since there is a decrease in interstellar extinction and Galactic background compared to optical wavelengths. An innovative Near-InfraRed and Optical SETI (NIROSETI) instrument has been designed and constructed to take advantage of a new generation of fast (> 1 Ghz) low-noise near-infrared avalanche photodiodes to search for nanosecond pulsed near-infrared (850 - 1650 nm) pulses. The instrument was successfully installed and commissioned at the Nickel (1m) telescope at Lick Observatory in March 2015. We will describe the overall design of the instrument with a focus on methods developed for data acquisition and reduction for near-infrared SETI. Time and height analyses of the pulses produced by the detectors are performed to search for periodicity and coincidences in the signals. We will further discuss our NIROSETI survey plans.

Peak holding circuit for extremely narrow pulses

NASA Technical Reports Server (NTRS)

Oneill, R. W. (Inventor)

1975-01-01

An improved pulse stretching circuit comprising: a high speed wide-band amplifier connected in a fast charge integrator configuration; a holding circuit including a capacitor connected in parallel with a discharging network which employs a resistor and an FET; and an output buffer amplifier. Input pulses of very short duration are applied to the integrator charging the capacitor to a value proportional to the input pulse amplitude. After a predetermined period of time, conventional circuitry generates a dump pulse which is applied to the gate of the FET making a low resistance path to ground which discharges the capacitor. When the dump pulse terminates, the circuit is ready to accept another pulse to be stretched. The very short input pulses are thus stretched in width so that they may be analyzed by conventional pulse height analyzers.

Characteristics of the pulse waveform during altered nitric oxide synthesis in the rabbit.

PubMed

Weinberg, P D; Habens, F; Kengatharan, M; Barnes, S E; Matz, J; Anggård, E E; Carrier, M J

2001-06-01

Nitrovasodilators produce characteristic changes in the shape of the peripheral pulse wave. Similar changes might also be caused by alteration of endogenous NO activity, which would allow such activity to be assessed in vivo. We investigated whether manipulation of the NO pathway influences the pulse waveform, and the mechanisms involved. The pulse wave in the ear of normal rabbits was examined by reflectance photoplethysmography before and during infusion of vasoactive agents. Pulse wave velocity was assessed by using an additional sensor on the rear foot. A diastolic peak was observed in the ear pulse; its timing was consistent with it being a reflection of the systolic peak from the lower body. The height of the dicrotic notch marking the start of this diastolic wave was decreased by acetylcholine or an NO donor, and further decreased by a phosphodiesterase type V inhibitor. The acetylcholine-induced decreases were blocked by inhibiting NO synthesis with N(G)-nitro-L-arginine methyl ester (L-NAME) but were unaffected by the inactive enantiomer D-NAME. These data demonstrate that NO influences the height of the notch in the pulse wave. Heart rate and blood pressure were altered during acetylcholine or L-NAME infusion, but there were no changes in pulse wave amplitude or velocity, or in the timing of the diastolic peak or dicrotic notch. The slope of the pulse wave between the systolic peak and notch changed substantially. These effects are most convincingly explained by changes in wave reflection, not only from the lower body but also from more proximal sites.

Characteristics of the pulse waveform during altered nitric oxide synthesis in the rabbit

PubMed Central

Weinberg, P D; Habens, F; Kengatharan, M; Barnes, S E; Matz, J; Änggård, E E; Carrier, M J

2001-01-01

Nitrovasodilators produce characteristic changes in the shape of the peripheral pulse wave. Similar changes might also be caused by alteration of endogenous NO activity, which would allow such activity to be assessed in vivo. We investigated whether manipulation of the NO pathway influences the pulse waveform, and the mechanisms involved. The pulse wave in the ear of normal rabbits was examined by reflectance photoplethysmography before and during infusion of vasoactive agents. Pulse wave velocity was assessed by using an additional sensor on the rear foot. A diastolic peak was observed in the ear pulse; its timing was consistent with it being a reflection of the systolic peak from the lower body. The height of the dicrotic notch marking the start of this diastolic wave was decreased by acetylcholine or an NO donor, and further decreased by a phosphodiesterase type V inhibitor. The acetylcholine-induced decreases were blocked by inhibiting NO synthesis with NG-nitro-L-arginine methyl ester (L-NAME) but were unaffected by the inactive enantiomer D-NAME. These data demonstrate that NO influences the height of the notch in the pulse wave. Heart rate and blood pressure were altered during acetylcholine or L-NAME infusion, but there were no changes in pulse wave amplitude or velocity, or in the timing of the diastolic peak or dicrotic notch. The slope of the pulse wave between the systolic peak and notch changed substantially. These effects are most convincingly explained by changes in wave reflection, not only from the lower body but also from more proximal sites. PMID:11375252

Short pulse radar used to measure sea surface wind speed and SWH. [Significant Wave Height

NASA Technical Reports Server (NTRS)

Hammond, D. L.; Mennella, R. A.; Walsh, E. J.

1977-01-01

A joint airborne measurement program is being pursued by NRL and NASA Wallops Flight Center to determine the extent to which wind speed and sea surface significant wave height (SWH) can be measured quantitatively and remotely with a short pulse (2 ns), wide-beam (60 deg), nadir-looking 3-cm radar. The concept involves relative power measurements only and does not need a scanning antenna, Doppler filters, or absolute power calibration. The slopes of the leading and trailing edges of the averaged received power for the pulse limited altimeter are used to infer SWH and surface wind speed. The interpretation is based on theoretical models of the effects of SWH on the leading edge shape and rms sea-surface slope on the trailing-edge shape. The models include the radar system parameters of antenna beam width and pulsewidth.

Advanced application flight experiment breadboard pulse compression radar altimeter program

NASA Technical Reports Server (NTRS)

1976-01-01

Design, development and performance of the pulse compression radar altimeter is described. The high resolution breadboard system is designed to operate from an aircraft at 10 Kft above the ocean and to accurately measure altitude, sea wave height and sea reflectivity. The minicomputer controlled Ku band system provides six basic variables and an extensive digital recording capability for experimentation purposes. Signal bandwidths of 360 MHz are obtained using a reflective array compression line. Stretch processing is used to achieve 1000:1 pulse compression. The system range command LSB is 0.62 ns or 9.25 cm. A second order altitude tracker, aided by accelerometer inputs is implemented in the system software. During flight tests the system demonstrated an altitude resolution capability of 2.1 cm and sea wave height estimation accuracy of 10%. The altitude measurement performance exceeds that of the Skylab and GEOS-C predecessors by approximately an order of magnitude.

The Algorithm Theoretical Basis Document for the Derivation of Range and Range Distributions from Laser Pulse Waveform Analysis for Surface Elevations, Roughness, Slope, and Vegetation Heights

NASA Technical Reports Server (NTRS)

Brenner, Anita C.; Zwally, H. Jay; Bentley, Charles R.; Csatho, Bea M.; Harding, David J.; Hofton, Michelle A.; Minster, Jean-Bernard; Roberts, LeeAnne; Saba, Jack L.; Thomas, Robert H.;

Neutron radiative capture methods for surface elemental analysis

USGS Publications Warehouse

Trombka, J.I.; Senftle, F.; Schmadebeck, R.

1970-01-01

Both an accelerator and a 252Cf neutron source have been used to induce characteristic gamma radiation from extended soil samples. To demonstrate the method, measurements of the neutron-induced radiative capture and activation gamma rays have been made with both Ge(Li) and NaI(Tl) detectors, Because of the possible application to space flight geochemical analysis, it is believed that NaI(Tl) detectors must be used. Analytical procedures have been developed to obtain both qualitative and semiquantitative results from an interpretation of the measured NaI(Tl) pulse-height spectrum. Experiment results and the analytic procedure are presented. ?? 1970.

Validation of the pulse decomposition analysis algorithm using central arterial blood pressure

PubMed Central

2014-01-01

Background There is a significant need for continuous noninvasive blood pressure (cNIBP) monitoring, especially for anesthetized surgery and ICU recovery. cNIBP systems could lower costs and expand the use of continuous blood pressure monitoring, lowering risk and improving outcomes. The test system examined here is the CareTaker® and a pulse contour analysis algorithm, Pulse Decomposition Analysis (PDA). PDA’s premise is that the peripheral arterial pressure pulse is a superposition of five individual component pressure pulses that are due to the left ventricular ejection and reflections and re-reflections from only two reflection sites within the central arteries. The hypothesis examined here is that the model’s principal parameters P2P1 and T13 can be correlated with, respectively, systolic and pulse pressures. Methods Central arterial blood pressures of patients (38 m/25 f, mean age: 62.7 y, SD: 11.5 y, mean height: 172.3 cm, SD: 9.7 cm, mean weight: 86.8 kg, SD: 20.1 kg) undergoing cardiac catheterization were monitored using central line catheters while the PDA parameters were extracted from the arterial pulse signal obtained non-invasively using CareTaker system. Results Qualitative validation of the model was achieved with the direct observation of the five component pressure pulses in the central arteries using central line catheters. Statistically significant correlations between P2P1 and systole and T13 and pulse pressure were established (systole: R square: 0.92 (p < 0.0001), diastole: R square: 0.78 (p < 0.0001). Bland-Altman comparisons between blood pressures obtained through the conversion of PDA parameters to blood pressures of non-invasively obtained pulse signatures with catheter-obtained blood pressures fell within the trend guidelines of the Association for the Advancement of Medical Instrumentation SP-10 standard (standard deviation: 8 mmHg(systole: 5.87 mmHg, diastole: 5.69 mmHg)). Conclusions The results indicate that arterial blood pressure can be accurately measured and tracked noninvasively and continuously using the CareTaker system and the PDA algorithm. The results further support the physical model that all of the features of the pressure pulse envelope, whether in the central arteries or in the arterial periphery, can be explained by the interaction of the left ventricular ejection pressure pulse with two centrally located reflection sites. PMID:25005686

Infrared focal plane performance in the South Atlantic anomaly

NASA Technical Reports Server (NTRS)

Junga, Frank A.

1989-01-01

Proton-induced pulse height distributions (PHD's) in Si:XX detectors were studied analytically and experimentally. In addition, a preliminary design for a flight experiment to characterize the response of Si:XX detectors to the trapped proton environment and verify PHD models was developed. PHD's were computed for two orbit altitudes for a variety of shielding configurations. Most of the proton-induced pulses have amplitudes less that about 3.5 x 10(exp 5) e-h pairs. Shielding has a small effect on the shape of the PHD's. The primary effect of shielding is to reduce the total number of pulses produced. Proton-induced PHD's in a Si:Sb focal plane array bombarded by a unidirectional 67-MeV beam were measured. The maximum pulse height recorded was 6 x 10(exp 5) pairs. The distribution had two peaks: the larger peak corresponded to 3.8 x 10(exp 5) pairs and the smaller peak to 1.2 x 10(exp 5) pairs. The maximum pulse height and the larger peak are within a factor of two of predicted values. The low-energy peak was not expected, but is believed to be an artifact of inefficient charge collection in the detector. The planned flight experiment will be conducted on a Space Shuttle flight. Lockheed's helium extended life dewar (HELD) will be used to provide the required cryogenic environment for the detector. Two bulk Si:Sb arrays and two Si:As impurity band conduction arrays will be tested. The tests will be conducted while the Space Shuttle passes through the South Atlantic Anomaly. PHD's will be recorded and responsivity changes tracked. This experiment will provide a new database on proton-induced PHD's, compare two infrared detector technologies in a space environment, and provide the data necessary to validate PHD modeling.

Radiation imaging apparatus

DOEpatents

Anger, H.O.; Martin, D.C.; Lampton, M.L.

1983-07-26

A radiation imaging system using a charge multiplier and a position sensitive anode in the form of periodically arranged sets of interconnected anode regions for detecting the position of the centroid of a charge cloud arriving thereat from the charge multiplier. Various forms of improved position sensitive anodes having single plane electrode connections are disclosed. Various analog and digital signal processing systems are disclosed, including systems which use the fast response of microchannel plates, anodes and preamps to perform scintillation pulse height analysis digitally. 15 figs.

ATS-6 - Synchronous orbit trapped radiation studies with an electron-proton spectrometer

NASA Technical Reports Server (NTRS)

Walker, R. J.; Swanson, R. L.; Winckler, J. R.; Erickson, K. N.

1975-01-01

The paper discusses the University of Minnesota experiment on ATS-6 designed to study the origin and dynamics of high-energy electrons and protons in the outer radiation belt and in the near-earth plasma sheet. The experiment consists of two nearly identical detector assemblies, each of which is a magnetic spectrometer containing four gold-silicon surface barrier detectors. The instrument provides a clean separation between protons and electrons by the combination of pulse height analysis and magnetic deflection.

A bismuth activation counter for high sensitivity pulsed 14 MeV neutrons

NASA Astrophysics Data System (ADS)

Burns, E. J. T.; Thacher, P. D.; Hassig, G. J.; Decker, R. D.; Romero, J. A.; Barrett, K. P.

2011-08-01

We have built a fast neutron bismuth activation counter that measures activation counts from pulsed 14-MeV neutron generators for incident neutron fluences between 30 and 300 neutrons/cm2 at 15.2 cm (6 in.). The activation counter consists of a large bismuth germanate (BGO) detector surrounded by a bismuth metal shield in front of and concentric with the cylindrical detector housing. The 14 MeV neutrons activate the 2.6-millisecond (ms) isomer in the shield and the detector by the reaction 209Bi (n,2nγ) 208mBi. The use of millisecond isomers and activation counting times minimizes the background from other activated materials and the environment. In addition to activation, the bismuth metal shields against other outside radiation sources. We have tested the bismuth activation counter, simultaneously, with two data acquisition systems (DASs) and both give similar results. The two-dimensional (2D) DAS and three dimensional (3D) DAS both consist of pulse height analysis (PHA) systems that can be used to discriminate against gamma radiations below 300 keV photon energy, so that the detector can be used strictly as a counter. If the counting time is restricted to less than 25 ms after the neutron pulse, there are less than 10 counts of background for single pulse operation in all our operational environments tested so far. High-fluence neutron generator operations are restricted by large dead times and pulse height saturation. When we operate our 3D DAS PHA system in list mode acquisition (LIST), real-time corrections to dead time or live time can be made on the scale of 1 ms time windows or dwell times. The live time correction is consistent with nonparalyzable models for dead time of 1.0±0.2 μs for our 3D DAS and 1.5±0.3 μs for our 2D DAS dominated by our fixed time width analog to digital converters (ADCs). With the same solid angle, we have shown that the bismuth activation counter has a factor of 4 increase in sensitivity over our lead activation counter, because of higher counts and negligible backgrounds.

Non-contact weight measurement of flat-faced pharmaceutical tablets using terahertz transmission pulse delay measurements.

PubMed

Bawuah, Prince; Silfsten, Pertti; Ervasti, Tuomas; Ketolainen, Jarkko; Zeitler, J Axel; Peiponen, Kai-Erik

2014-12-10

By measuring the time delay of a terahertz pulse traversing a tablet, and hence its effective refractive index, it is possible to non-invasively and non-destructively detect the weight of tablets made of microcrystalline cellulose (MCC). Two sets of MCC tablets were used in the study: Set A (training set) consisted of 13 tablets with nominally constant height but varying porosities, whereas Set B (test set) comprised of 21 tablets with nominally constant porosity but different heights. A linear correlation between the estimated absolute weight based on the terahertz measurement and the measured weight of both sets of MCC tablets was found. In addition, it was possible to estimate the height of the tablets by utilizing the estimated absolute weight and calculating the relative change of height of each tablet with respect to an ideal tablet. A good agreement between the experimental and the calculated results was found highlighting the potential of this technique for in-line sensing of the weight, porosity and the relative change in height of the tablets compared to a reference/ideal tablet. In this context, we propose a quantitative quality control method to assess the deviations in porosity of tablets immediately after compaction. Copyright © 2014 Elsevier B.V. All rights reserved.

Femtosecond versus picosecond laser pulses for film-free laser bioprinting.

PubMed

Petit, Stephane; Kérourédan, Olivia; Devillard, Raphael; Cormier, Eric

2017-11-01

We investigate the properties of microjets in the context of film-free laser induced forward transfer in the femtosecond and picosecond regimes. The influence of the pulse duration (ranging from 0.4 to 12 ps) and the energy (ranging from 6 to 12 μJ) is systematically studied on the height, diameter, speed, volume, and shape of the jets. The 400 fs pulses generate thin and stable jets compatible with bioprinting, while 14 ps pulses generate more unstable jets. A pulse duration around 8 ps seems, therefore, to be an interesting trade-off to cover many bio-applications of microjets generated by lasers.

Optimization of Surface Roughness Parameters of Al-6351 Alloy in EDC Process: A Taguchi Coupled Fuzzy Logic Approach

NASA Astrophysics Data System (ADS)

Kar, Siddhartha; Chakraborty, Sujoy; Dey, Vidyut; Ghosh, Subrata Kumar

2017-10-01

This paper investigates the application of Taguchi method with fuzzy logic for multi objective optimization of roughness parameters in electro discharge coating process of Al-6351 alloy with powder metallurgical compacted SiC/Cu tool. A Taguchi L16 orthogonal array was employed to investigate the roughness parameters by varying tool parameters like composition and compaction load and electro discharge machining parameters like pulse-on time and peak current. Crucial roughness parameters like Centre line average roughness, Average maximum height of the profile and Mean spacing of local peaks of the profile were measured on the coated specimen. The signal to noise ratios were fuzzified to optimize the roughness parameters through a single comprehensive output measure (COM). Best COM obtained with lower values of compaction load, pulse-on time and current and 30:70 (SiC:Cu) composition of tool. Analysis of variance is carried out and a significant COM model is observed with peak current yielding highest contribution followed by pulse-on time, compaction load and composition. The deposited layer is characterised by X-Ray Diffraction analysis which confirmed the presence of tool materials on the work piece surface.

High rate tests of the photon detection system for the LHCb RICH Upgrade

NASA Astrophysics Data System (ADS)

Blago, M. P.; Keizer, F.

2017-12-01

The photon detection system for the LHCb RICH Upgrade consists of an array of multianode photomultiplier tubes (MaPMTs) read out by custom-built modular electronics. The behaviour of the whole chain was studied at CERN using a pulsed laser. Threshold scans were performed in order to study the MaPMT pulse-height spectra at high event rates and different photon intensities. The results show a reduction in photon detection efficiency at 900 V bias voltage, marked by a 20% decrease in the single-photon peak height, when increasing the event rate from 100 kHz to 20 MHz. This reduction was not observed at 1000 V bias voltage.

Watering the Tree of Science: Science Education, Local Knowledge, and Agency in Zambia's PSA Program

NASA Astrophysics Data System (ADS)

Lample, Emily

With increased public interest in protecting the environment, scientists and engineers aim to improve energy conversion efficiency. Thermoelectrics offer many advantages as thermal management technology. When compared to vapor compression refrigeration, above approximately 200 to 600 watts, cost in dollars per watt as well as COP are not advantageous for thermoelectrics. The goal of this work was to determine if optimized pulse supercooling operation could improve cooling capacity or efficiency of a thermoelectric device. The basis of this research is a thermal-electrical analogy based modeling study using SPICE. Two models were developed. The first model, a standalone thermocouple with no attached mass to be cooled. The second, a system that includes a module attached to a heat generating mass. With the thermocouple study, a new approach of generating response surfaces with characteristic parameters was applied. The current pulse height and pulse on-time was identified for maximizing Net Transient Advantage, a newly defined metric. The corresponding pulse height and pulse on-time was utilized for the system model. Along with the traditional steady state starting current of Imax, Iopt was employed. The pulse shape was an isosceles triangle. For the system model, metrics new to pulse cooling were Qc, power consumption and COP. The effects of optimized current pulses were studied by changing system variables. Further studies explored time spacing between pulses and temperature distribution in the thermoelement. It was found net Q c over an entire pulse event can be improved over Imax steady operation but not over steady I opt operation. Qc can be improved over Iopt operation but only during the early part of the pulse event. COP is reduced in transient pulse operation due to the different time constants of Qc and Pin. In some cases lower performance interface materials allow more Qc and better COP during transient operation than higher performance interface materials. Important future work might look at developing innovative ways of biasing Joule heat to Th..

Recent advances in chemical synthesis methodology of inorganic materials and theoretical computations of metal nanoparticles/carbon interfaces

NASA Astrophysics Data System (ADS)

Harris, Andrew G.

With increased public interest in protecting the environment, scientists and engineers aim to improve energy conversion efficiency. Thermoelectrics offer many advantages as thermal management technology. When compared to vapor compression refrigeration, above approximately 200 to 600 watts, cost in dollars per watt as well as COP are not advantageous for thermoelectrics. The goal of this work was to determine if optimized pulse supercooling operation could improve cooling capacity or efficiency of a thermoelectric device. The basis of this research is a thermal-electrical analogy based modeling study using SPICE. Two models were developed. The first model, a standalone thermocouple with no attached mass to be cooled. The second, a system that includes a module attached to a heat generating mass. With the thermocouple study, a new approach of generating response surfaces with characteristic parameters was applied. The current pulse height and pulse on-time was identified for maximizing Net Transient Advantage, a newly defined metric. The corresponding pulse height and pulse on-time was utilized for the system model. Along with the traditional steady state starting current of Imax, Iopt was employed. The pulse shape was an isosceles triangle. For the system model, metrics new to pulse cooling were Qc, power consumption and COP. The effects of optimized current pulses were studied by changing system variables. Further studies explored time spacing between pulses and temperature distribution in the thermoelement. It was found net Q c over an entire pulse event can be improved over Imax steady operation but not over steady I opt operation. Qc can be improved over Iopt operation but only during the early part of the pulse event. COP is reduced in transient pulse operation due to the different time constants of Qc and Pin. In some cases lower performance interface materials allow more Qc and better COP during transient operation than higher performance interface materials. Important future work might look at developing innovative ways of biasing Joule heat to Th..

Soft error aware physical synthesis

NASA Astrophysics Data System (ADS)

Assis, Thiago Rocha de

With increased public interest in protecting the environment, scientists and engineers aim to improve energy conversion efficiency. Thermoelectrics offer many advantages as thermal management technology. When compared to vapor compression refrigeration, above approximately 200 to 600 watts, cost in dollars per watt as well as COP are not advantageous for thermoelectrics. The goal of this work was to determine if optimized pulse supercooling operation could improve cooling capacity or efficiency of a thermoelectric device. The basis of this research is a thermal-electrical analogy based modeling study using SPICE. Two models were developed. The first model, a standalone thermocouple with no attached mass to be cooled. The second, a system that includes a module attached to a heat generating mass. With the thermocouple study, a new approach of generating response surfaces with characteristic parameters was applied. The current pulse height and pulse on-time was identified for maximizing Net Transient Advantage, a newly defined metric. The corresponding pulse height and pulse on-time was utilized for the system model. Along with the traditional steady state starting current of Imax, Iopt was employed. The pulse shape was an isosceles triangle. For the system model, metrics new to pulse cooling were Qc, power consumption and COP. The effects of optimized current pulses were studied by changing system variables. Further studies explored time spacing between pulses and temperature distribution in the thermoelement. It was found net Q c over an entire pulse event can be improved over Imax steady operation but not over steady I opt operation. Qc can be improved over Iopt operation but only during the early part of the pulse event. COP is reduced in transient pulse operation due to the different time constants of Qc and Pin. In some cases lower performance interface materials allow more Qc and better COP during transient operation than higher performance interface materials. Important future work might look at developing innovative ways of biasing Joule heat to Th..

Unstable and multiple pulsing can be invisible to ultrashort pulse measurement techniques

DOE PAGES

Rhodes, Michelle A.; Guang, Zhe; Trebino, Rick

2016-12-29

Here, multiple pulsing occurs in most ultrashort-pulse laser systems when pumped at excessively high powers, and small fluctuations in pump power in certain regimes can cause unusual variations in the temporal separations of sub-pulses. Unfortunately, the ability of modern intensity-and-phase pulse measurement techniques to measure such unstable multi-pulsing has not been studied. Here we report calculations and simulations finding that allowing variations in just the relative phase of a satellite pulse causes the second pulse to completely disappear from a spectral interferometry for direct electric field reconstruction (SPIDER) measurement. We find that, although neither frequency-resolved optical gating (FROG) nor autocorrelationmore » can determine the precise properties of satellite pulses due to the presence of instability, they always succeed in, at least, seeing the satellite pulses. Also, additional post-processing of the measured FROG trace can determine the correct approximate relative height of the satellite pulse and definitively indicate the presence of unstable multiple-pulsing.« less

Unstable and multiple pulsing can be invisible to ultrashort pulse measurement techniques

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

Rhodes, Michelle A.; Guang, Zhe; Trebino, Rick

Here, multiple pulsing occurs in most ultrashort-pulse laser systems when pumped at excessively high powers, and small fluctuations in pump power in certain regimes can cause unusual variations in the temporal separations of sub-pulses. Unfortunately, the ability of modern intensity-and-phase pulse measurement techniques to measure such unstable multi-pulsing has not been studied. Here we report calculations and simulations finding that allowing variations in just the relative phase of a satellite pulse causes the second pulse to completely disappear from a spectral interferometry for direct electric field reconstruction (SPIDER) measurement. We find that, although neither frequency-resolved optical gating (FROG) nor autocorrelationmore » can determine the precise properties of satellite pulses due to the presence of instability, they always succeed in, at least, seeing the satellite pulses. Also, additional post-processing of the measured FROG trace can determine the correct approximate relative height of the satellite pulse and definitively indicate the presence of unstable multiple-pulsing.« less

Fieldable computer system for determining gamma-ray pulse-height distributions, flux spectra, and dose rates from Little Boy

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

Moss, C.E.; Lucas, M.C.; Tisinger, E.W.

1984-01-01

Our system consists of a LeCroy 3500 data acquisition system with a built-in CAMAC crate and eight bismuth-germanate detectors 7.62 cm in diameter and 7.62 cm long. Gamma-ray pulse-height distributions are acquired simultaneously for up to eight positions. The system was very carefully calibrated and characterized from 0.1 to 8.3 MeV using gamma-ray spectra from a variety of radioactive sources. By fitting the pulse-height distributions from the sources with a function containing 17 parameters, we determined theoretical repsonse functions. We use these response functions to unfold the distributions to obtain flux spectra. A flux-to-dose-rate conversion curve based on the workmore » of Dimbylow and Francis is then used to obtain dose rates. Direct use of measured spectra and flux-to-dose-rate curves to obtain dose rates avoids the errors that can arise from spectrum dependence in simple gamma-ray dosimeter instruments. We present some gamma-ray doses for the Little Boy assembly operated at low power. These results can be used to determine the exposures of the Hiroshima survivors and thus aid in the establishment of radation exposure limits for the nuclear industry.« less

Sensitivity analysis of pulse pileup model parameter in photon counting detectors

NASA Astrophysics Data System (ADS)

Shunhavanich, Picha; Pelc, Norbert J.

2017-03-01

Photon counting detectors (PCDs) may provide several benefits over energy-integrating detectors (EIDs), including spectral information for tissue characterization and the elimination of electronic noise. PCDs, however, suffer from pulse pileup, which distorts the detected spectrum and degrades the accuracy of material decomposition. Several analytical models have been proposed to address this problem. The performance of these models are dependent on the assumptions used, including the estimated pulse shape whose parameter values could differ from the actual physical ones. As the incident flux increases and the corrections become more significant the needed parameter value accuracy may be more crucial. In this work, the sensitivity of model parameter accuracies is analyzed for the pileup model of Taguchi et al. The spectra distorted by pileup at different count rates are simulated using either the model or Monte Carlo simulations, and the basis material thicknesses are estimated by minimizing the negative log-likelihood with Poisson or multivariate Gaussian distributions. From simulation results, we find that the accuracy of the deadtime, the height of pulse negative tail, and the timing to the end of the pulse are more important than most other parameters, and they matter more with increasing count rate. This result can help facilitate further work on parameter calibrations.

PULSE AMPLITUDE ANALYZER

DOEpatents

Greenblatt, M.H.

1958-03-25

This patent pertains to pulse amplitude analyzers for sorting and counting a serles of pulses, and specifically discloses an analyzer which ls simple in construction and presents the puise height distribution visually on an oscilloscope screen. According to the invention, the pulses are applied to the vertical deflection plates of an oscilloscope and trigger the horizontal sweep. Each pulse starts at the same point on the screen and has a maximum amplitude substantially along the same vertical line. A mask is placed over the screen except for a slot running along the line where the maximum amplitudes of the pulses appear. After the slot has been scanned by a photocell in combination with a slotted rotating disk, the photocell signal is displayed on an auxiliary oscilloscope as vertical deflection along a horizontal time base to portray the pulse amplitude distribution.

Xenon excimer emission from pulsed high-pressure capillary microdischarges

NASA Astrophysics Data System (ADS)

Lee, Byung-Joon; Rahaman, Hasibur; Petzenhauser, Isfried; Frank, Klaus; Giapis, Konstantinos P.

2007-06-01

Intense xenon vacuum ultraviolet (VUV) emission is observed from a high-pressure capillary cathode microdischarge in direct current operation, by superimposing a high-voltage pulse of 50ns duration. Under stagnant gas conditions, the total VUV light intensity increases linearly with pressure from 400 to 1013mbar for a fixed voltage pulse. At fixed pressure, however, the VUV light intensity increases superlinearly with voltage pulse height ranging from 08to2.8kV. Gains in emission intensity are obtained by inducing gas flow through the capillary cathode, presumably because of excimer dimer survival due to gas cooling.

Linear operating region in the ozone dial photon counting system

NASA Technical Reports Server (NTRS)

Andrawis, Madeleine

1995-01-01

Ozone is a relatively unstable molecule found in Earth's atmosphere. An ozone molecule is made up of three atoms of oxygen. Depending on where ozone resides, it can protect or harm life on Earth. High in the atmosphere, about 15 miles up, ozone acts as a shield to protect Earth's surface from the sun's harmful ultraviolet radiation. Without this shield, we would be more susceptible to skin cancer, cataracts, and impaired immune systems. Closer to Earth, in the air we breathe, ozone is a harmful pollutant that causes damage to lung tissue and plants. Since the early 1980's, airborne lidar systems have been used for making measurements of ozone. The differential absorption lidar (DIAL) technique is used in the remote measurement of O3. This system allows the O3 to be measured as function of the range in the atmosphere. Two frequency-doubled Nd:YAG lasers are used to pump tunable dye lasers. The lasers are operating at 289 nm for the DIAL on-line wavelength of O3, and the other one is operated at 300 nm for the off-line wavelength. The DIAL wavelengths are produced in sequential laser pulses with a time separation of 300 micro s. The backscattered laser energy is collected by telescopes and measured using photon counting systems. The photon counting system measures the light signal by making use of the photon nature of light. The output pulse from the Photo-Multiplier Tube (PE), caused by a photon striking the PMT photo-cathode, is amplified and passed to a pulse height discriminator. The peak value of the pulse is compared to a reference voltage (discrimination level). If the pulse amplitude exceeds the discrimination level, the discriminator generates a standard pulse which is counted by the digital counter. Non-linearity in the system is caused by the overlapping of pulses and the finite response time of the electronics. At low count rates one expects the system to register one event for each output pulse from the PMT corresponding to a photon incident upon the photocathode, however, at higher rates the limitations of the discrimination/counting system will cause the observed count rate to be non-linear with respect to the true count rate. Depending on the pulse height distribution and the discriminator level, the overlapping of pulses (pulse pile-up) can cause count loss or even an additional apparent count gain as the signal levels increase. Characterization of the system, including the pulse height distribution, the signal to noise ratio, and the effect of the discriminator threshold level, is critical in maximizing the linear operating region of the system, thus greatly increasing the useful dynamic range of the system.

Optimization of a Fast Neutron Scintillator for Real-Time Pulse Shape Discrimination in the Transient Reactor Test Facility (TREAT) Hodoscope

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

Johnson, James T.; Thompson, Scott J.; Watson, Scott M.

We present a multi-channel, fast neutron/gamma ray detector array system that utilizes ZnS(Ag) scintillator detectors. The system employs field programmable gate arrays (FPGAs) to do real-time all digital neutron/gamma ray discrimination with pulse height and time histograms to allow count rates in excess of 1,000,000 pulses per second per channel. The system detector number is scalable in blocks of 16 channels.

High-speed pulse-shape generator, pulse multiplexer

DOEpatents

Burkhart, Scott C.

2002-01-01

The invention combines arbitrary amplitude high-speed pulses for precision pulse shaping for the National Ignition Facility (NIF). The circuitry combines arbitrary height pulses which are generated by replicating scaled versions of a trigger pulse and summing them delayed in time on a pulse line. The combined electrical pulses are connected to an electro-optic modulator which modulates a laser beam. The circuit can also be adapted to combine multiple channels of high speed data into a single train of electrical pulses which generates the optical pulses for very high speed optical communication. The invention has application in laser pulse shaping for inertial confinement fusion, in optical data links for computers, telecommunications, and in laser pulse shaping for atomic excitation studies. The invention can be used to effect at least a 10.times. increase in all fiber communication lines. It allows a greatly increased data transfer rate between high-performance computers. The invention is inexpensive enough to bring high-speed video and data services to homes through a super modem.

Characteristics of haze and the atmospheric boundary layer height during the periods with different category of haze over Suzhou observed by Micro-Pulse Lidar

NASA Astrophysics Data System (ADS)

Huijuan, L.

2015-12-01

Based on the observed hourly meterological data, atmospheric composition data, and the Micro-Pulse Lidar (MPL) detecting data over Suzhou during 2010 to 2014, this study concentrates on revealing the characteristics of haze weather and the atmospheric boundary layer height during the periods with different category of haze over Suzhou. The main results are shown as follows: The haze frequency over Suzhou is 30.9% with the frequency of 18% for the slight haze, 7.8% for the light haze, 3.1% for the moderate haze and 2.0% for the heavy haze. The haze frequency shows an obvious diurnal variation with a peak (valley) value at the local solar time around 08:00~09:00 am (14:00~16:00pm).The haze happens much more frequent in nighttime than in daytime. The atmospheric boundary layer height (ABLH) associated with haze also shows a clear diurnal variation. The mean ABLH over Suzhou during the period of haze is more (less) than 1000m (500m) in daytime (nighttime). Meanwhile, the ABLH during the period of haze is higher in summer than in winter. In addition, the mean ABLH during the period without (with) haze is around 700m (500m) in winter. The diurnal variation of the ABLH during the period of moderate to heavy haze in winter ranges from 350m to 500m, which is less than the winter mean ABLH by 50~150m. KEY WORDS: Micro-Pulse Lidar; haze frequency; moderate and heavy haze；atmospheric boundary layer height

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

Wang, C. L.; Funk, L. L.; Riedel, R. A.

3He gas based neutron linear-position-sensitive detectors (LPSDs) have been applied for many neutron scattering instruments. Traditional Pulse-Height Analysis (PHA) for Neutron-Gamma Discrimination (NGD) resulted in the neutron-gamma efficiency ratio on the orders of 10 5-10 6. The NGD ratios of 3He detectors need to be improved for even better scientific results from neutron scattering. Digital Signal Processing (DSP) analyses of waveforms were proposed for obtaining better NGD ratios, based on features extracted from rise-time, pulse amplitude, charge integration, a simplified Wiener filter, and the cross-correlation between individual and template waveforms of neutron and gamma events. Fisher linear discriminant analysis (FLDA)more » and three multivariate analyses (MVAs) of the features were performed. The NGD ratios are improved by about 10 2-10 3 times compared with the traditional PHA method. Finally, our results indicate the NGD capabilities of 3He tube detectors can be significantly improved with subspace-learning based methods, which may result in a reduced data-collection time and better data quality for further data reduction.« less

Elastic and Inelastic Scattering of Neutrons using a CLYC array

NASA Astrophysics Data System (ADS)

Brown, Tristan; Doucet, E.; Chowdhury, P.; Lister, C. J.; Wilson, G. L.; Devlin, M.; Mosby, S.

2015-10-01

CLYC scintillators, which have dual neutron and gamma response, have recently ushered in the possibility of fast neutron spectroscopy without time-of-flight (TOF). A 16-element array of 1'' x 1'' 6Li-depleted CLYC crystals, where pulse-shape-discrimination is achieved via digital pulse processing, has been commissioned at UMass Lowell. In an experiment at LANSCE, high energy neutrons were used to bombard 56Fe and 238U targets, in order to measure elastic and inelastic neutron scattering cross sections as a function of energy and angle with the array. The array is placed very close to the targets for enhanced geometrical solid angles for scattered neutrons compared to standard neutron-TOF measurements. A pulse-height spectrum of scattered neutrons in the detectors is compared to the energy of the incident neutrons, which is measured via the TOF of the pulsed neutrons from the source to the detectors. Recoil corrections are necessary to combine the energy spectra from all the detectors to obtain angle-integrated elastic and inelastic cross-sections. The detection techniques, analysis procedures and results will be presented. Supported by NNSA-SSAA program through DOE Grant DE-NA00013008.

Factors associated with arterial stiffness in children aged 9-10 years

PubMed Central

Batista, Milena Santos; Mill, José Geraldo; Pereira, Taisa Sabrina Silva; Fernandes, Carolina Dadalto Rocha; Molina, Maria del Carmen Bisi

2015-01-01

OBJECTIVE To analyze the factors associated with stiffness of the great arteries in prepubertal children. METHODS This study with convenience sample of 231 schoolchildren aged 9-10 years enrolled in public and private schools in Vitória, ES, Southeastern Brazil, in 2010-2011. Anthropometric and hemodynamic data, blood pressure, and pulse wave velocity in the carotid-femoral segment were obtained. Data on current and previous health conditions were obtained by questionnaire and notes on the child’s health card. Multiple linear regression was applied to identify the partial and total contribution of the factors in determining the pulse wave velocity values. RESULTS Among the students, 50.2% were female and 55.4% were 10 years old. Among those classified in the last tertile of pulse wave velocity, 60.0% were overweight, with higher mean blood pressure, waist circumference, and waist-to-height ratio. Birth weight was not associated with pulse wave velocity. After multiple linear regression analysis, body mass index (BMI) and diastolic blood pressure remained in the model. CONCLUSIONS BMI was the most important factor in determining arterial stiffness in children aged 9-10 years. PMID:25902563

Role of thermal stresses on pulsed laser irradiation of thin films under conditions of microbump formation and nonvaporization forward transfer

NASA Astrophysics Data System (ADS)

Meshcheryakov, Yuri P.; Shugaev, Maxim V.; Mattle, Thomas; Lippert, Thomas; Bulgakova, Nadezhda M.

2013-11-01

This paper presents a theoretical analysis of the processes in thin solid films irradiated by short and ultrashort laser pulses in the regimes of film structuring and laser-induced forward transfer. The regimes are considered at which vaporization of the film materials is insignificant and film dynamics is governed mainly by mechanical processes. Thermoelastoplastic modeling has been performed for a model film in one- and two-dimensional geometries. A method has been proposed to estimate the height of microbumps produced by nanosecond laser irradiation of solid films. Contrary to femtosecond laser pulses, in nanosecond pulse regimes, stress waves across the film are weak and cannot induce film damage. The main role in laser-induced dynamics of irradiated films is played by radial thermal stresses which lead to the formation of a bending wave propagating along the film and drawing the film matter to the center of the irradiation spot. The bending wave dynamics depends on the hardness of the substrate underlying the film. The causes of the receiver substrate damage sometimes observed upon laser-induced forward transfer in the scheme of the direct contact between the film and the receiver are discussed.

Transient thermoelectric supercooling: Isosceles current pulses from a response surface perspective and the performance effects of pulse cooling a heat generating mass

NASA Astrophysics Data System (ADS)

Piggott, Alfred J., III

With increased public interest in protecting the environment, scientists and engineers aim to improve energy conversion efficiency. Thermoelectrics offer many advantages as thermal management technology. When compared to vapor compression refrigeration, above approximately 200 to 600 watts, cost in dollars per watt as well as COP are not advantageous for thermoelectrics. The goal of this work was to determine if optimized pulse supercooling operation could improve cooling capacity or efficiency of a thermoelectric device. The basis of this research is a thermal-electrical analogy based modeling study using SPICE. Two models were developed. The first model, a standalone thermocouple with no attached mass to be cooled. The second, a system that includes a module attached to a heat generating mass. With the thermocouple study, a new approach of generating response surfaces with characteristic parameters was applied. The current pulse height and pulse on-time was identified for maximizing Net Transient Advantage, a newly defined metric. The corresponding pulse height and pulse on-time was utilized for the system model. Along with the traditional steady state starting current of Imax, Iopt was employed. The pulse shape was an isosceles triangle. For the system model, metrics new to pulse cooling were Qc, power consumption and COP. The effects of optimized current pulses were studied by changing system variables. Further studies explored time spacing between pulses and temperature distribution in the thermoelement. It was found net Q c over an entire pulse event can be improved over Imax steady operation but not over steady I opt operation. Qc can be improved over Iopt operation but only during the early part of the pulse event. COP is reduced in transient pulse operation due to the different time constants of Qc and Pin. In some cases lower performance interface materials allow more Qc and better COP during transient operation than higher performance interface materials. Important future work might look at developing innovative ways of biasing Joule heat to Th..

Comparative Analysis of Methods of Evaluating the Lower Ionosphere Parameters by Tweek Atmospherics

NASA Astrophysics Data System (ADS)

Krivonos, A. P.; Shvets, A. V.

2016-12-01

Purpose: A comparative analysis of the phase and frequency methods for determining the Earth-ionosphere effective waveguide heights for the basic and higher types of normal waves (modes) and distance to the source of radiation - lightning - has been made by analyzing pulse signals in the ELF-VLF range - tweek-atmospherics (tweeks). Design/methodology/approach: To test the methods in computer simulations, the tweeks waveforms were synthesized for the Earth-ionosphere waveguide model with the exponential conductivity profile of the lower ionosphere. The calculations were made for a 20-40 dB signal/noise ratio. Findings: The error of the frequency method of determining the effective height of the waveguide for different waveguide modes was less than 0.5 %. The error of the phase method for determining the effective height of the waveguide was less than 0.8 %. Errors in determining the distance to the lightning was less than 1 % for the phase method, and less than 5 % for the frequency method for the source ranges 1000-3000 km. Conclusions: The analysis results have showed the accuracy of the frequency and phase methods being practically the same within distances of 1000-3000 km. For distances less than 1000 km, the phase method shows a more accurate evaluation of the range, so the combination of the two methods can be used to improve estimating the tweek’s propagation path parameters.

Study on the keV neutron capture reaction in 56Fe and 57Fe

NASA Astrophysics Data System (ADS)

Wang, Taofeng; Lee, Manwoo; Kim, Guinyun; Ro, Tae-Ik; Kang, Yeong-Rok; Igashira, Masayuki; Katabuchi, Tatsuya

2014-03-01

The neutron capture cross-sections and the radiative capture gamma-ray spectra from the broad resonances of 56Fe and 57Fe in the neutron energy range from 10 to 90keV and 550keV have been measured with an anti-Compton NaI(Tl) detector. Pulsed keV neutrons were produced from the 7Li 7Be reaction by bombarding the lithium target with the 1.5ns bunched proton beam from the 3MV Pelletron accelerator. The incident neutron spectrum on a capture sample was measured by means of a time-of-flight (TOF) method with a 6Li -glass detector. The number of weighted capture counts of the iron or gold sample was obtained by applying a pulse height weighting technique to the corresponding capture gamma-ray pulse height spectrum. The neutron capture gamma-ray spectra were obtained by unfolding the observed capture gamma-ray pulse height spectra. To achieve further understanding on the mechanism of neutron radiative capture reaction and study on physics models, theoretical calculations of the -ray spectra for 56Fe and 57Fe with the POD program have been performed by applying the Hauser-Feshbach statistical model. The dominant ingredients to perform the statistical calculation were the Optical Model Potential (OMP), the level densities described by the Mengoni-Nakajima approach, and the -ray transmission coefficients described by -ray strength functions. The comparison of the theoretical calculations, performed only for the 550keV point, show a good agreement with the present experimental results.

RALPH: An online computer program for acquisition and reduction of pulse height data

NASA Technical Reports Server (NTRS)

Davies, R. C.; Clark, R. S.; Keith, J. E.

1973-01-01

A background/foreground data acquisition and analysis system incorporating a high level control language was developed for acquiring both singles and dual parameter coincidence data from scintillation detectors at the Radiation Counting Laboratory at the NASA Manned Spacecraft Center in Houston, Texas. The system supports acquisition of gamma ray spectra in a 256 x 256 coincidence matrix (utilizing disk storage) and simultaneous operation of any of several background support and data analysis functions. In addition to special instruments and interfaces, the hardware consists of a PDP-9 with 24K core memory, 256K words of disk storage, and Dectape and Magtape bulk storage.

Additional conformer observed in the microwave spectrum of methyl vinyl ketone

NASA Astrophysics Data System (ADS)

Wilcox, David S.; Shirar, Amanda J.; Williams, Owen L.; Dian, Brian C.

2011-05-01

A chirped-pulse Fourier transform microwave spectrometer was used to record the rotational spectrum of methyl vinyl ketone (MVK, 3-butene-2-one). Two stable conformations were identified: the previously documented antiperiplanar (ap) conformer and synperiplanar (sp), which is reported for the first time in this microwave study. Methyl torsional analysis resulted in V3 barrier heights of 433.8(1) and 376.6(2) cm-1 for ap- and sp-MVK, respectively. Heavy atom isotopic species of both conformers were detected in natural abundance allowing bond lengths and angles of the molecular frames to be calculated through Kraitchman analysis. A comparison with ab initio calculations is included.

Calibration of LiBaF3: Ce Scintillator for Fission Spectrum Neutrons

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

Reeder, Paul L.; Bowyer, Sonya M.

2002-05-21

The scintillator LiBaF3 doped with small amounts of Ce+3 has the ability to distinguish heavy charged particles (p, d, t, or a) from beta and/or gamma radiation based on the presence or absence of ns components in the scintillation light output. Because the neutron capture reaction on 6Li produces recoil alphas and tritons, this scintillator also discriminates between neutron induced events and beta or gamma interactions. An experimental technique using a time-tagged 252Cf source has been used to measure the efficiency of this scintillator for neutron capture, the calibration of neutron capture pulse height, and the pulse height resolution -more » all as a function of incident neutron energy.« less

Radiation effects studies for the high-resolution spectrograph

NASA Technical Reports Server (NTRS)

Smith, L. C.; Becher, J.

1982-01-01

The generation and collection of charge carriers created during the passage of energetic protons through a silicon photodiode array are modeled. Pulse height distributions of noise charge collected during exposure of a digicon type diode array to 21 and 75 MeV protons were obtained. The magnitude of charge collected by a diode from each proton event is determined not only by diffusion, but by statistical considerations involving the ionization process itself. Utilizing analytical solutions to the diffusion equation for transport of minority carriers, together with the Vavilov theory of energy loss fluctuations in thin absorbers, simulations of the pulse height spectra which follow the experimental distributions fairly well are presented and an estimate for the minority carrier diffusion length L sub d is provided.

Tachometer

NASA Technical Reports Server (NTRS)

Nola, F. J. (Inventor)

1977-01-01

A tachometer in which sine and cosine signals responsive to the angular position of a shaft as it rotates are each multiplied by like, sine or cosine, functions of a carrier signal, the products summed, and the resulting frequency signal converted to fixed height, fixed width pulses of a like frequency. These pulses are then integrated, and the resulting dc output is an indication of shaft speed.

Gain Shift Corrections at Chi-Nu

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

Brown, Tristan Brooks; Devlin, Matthew James

Ambient conditions have the potential to cause changes in liquid scintillator detector gain that vary with time and temperature. These gain shifts can lead to poor resolution in both energy as well as pulse shape discrimination. In order to correct for these shifts in the Chi-Nu high energy array, a laser system has been developed for calibration of the pulse height signals.

Electromagnetic wave scattering from rough terrain

NASA Astrophysics Data System (ADS)

Papa, R. J.; Lennon, J. F.; Taylor, R. L.

1980-09-01

This report presents two aspects of a program designed to calculate electromagnetic scattering from rough terrain: (1) the use of statistical estimation techniques to determine topographic parameters and (2) the results of a single-roughness-scale scattering calculation based on those parameters, including comparison with experimental data. In the statistical part of the present calculation, digitized topographic maps are used to generate data bases for the required scattering cells. The application of estimation theory to the data leads to the specification of statistical parameters for each cell. The estimated parameters are then used in a hypothesis test to decide on a probability density function (PDF) that represents the height distribution in the cell. Initially, the formulation uses a single observation of the multivariate data. A subsequent approach involves multiple observations of the heights on a bivariate basis, and further refinements are being considered. The electromagnetic scattering analysis, the second topic, calculates the amount of specular and diffuse multipath power reaching a monopulse receiver from a pulsed beacon positioned over a rough Earth. The program allows for spatial inhomogeneities and multiple specular reflection points. The analysis of shadowing by the rough surface has been extended to the case where the surface heights are distributed exponentially. The calculated loss of boresight pointing accuracy attributable to diffuse multipath is then compared with the experimental results. The extent of the specular region, the use of localized height variations, and the effect of the azimuthal variation in power pattern are all assessed.

Optimal Pulse Processing, Pile-Up Decomposition, and Applications of Silicon Drift Detectors at LCLS

DOE PAGES

Blaj, G.; Kenney, C. J.; Dragone, A.; ...

2017-10-11

Silicon drift detectors (SDDs) revolutionized spectroscopy in fields as diverse as geology and dentistry. For a subset of experiments at ultrafast, X-ray free-electron lasers (FELs), SDDs can make substantial contributions. Often the unknown spectrum is interesting, carrying science data, or the background measurement is useful to identify unexpected signals. Many measurements involve only several discrete photon energies known a priori, allowing single-event decomposition of pile-up and spectroscopic photon counting. We designed a pulse function and demonstrated that the signal amplitude (i.e., proportional to the detected energy and obtained from fitting with the pulse function), rise time, and pulse height aremore » interrelated, and at short peaking times, the pulse height and pulse area are not optimal estimators for detected energy; instead, the signal amplitude and rise time are obtained for each pulse by fitting, thus removing the need for pulse shaping. By avoiding pulse shaping, rise times of tens of nanoseconds resulted in reduced pulse pile-up and allowed decomposition of remaining pulse pile-up at photon separation times down to hundreds of nanoseconds while yielding time-of-arrival information with the precision of 10 ns. Waveform fitting yields simultaneously high energy resolution and high counting rates (two orders of magnitude higher than current digital pulse processors). At pulsed sources or high photon rates, photon pile-up still occurs. We showed that pile-up spectrum fitting is relatively simple and preferable to pile-up spectrum deconvolution. We then developed a photon pile-up statistical model for constant intensity sources, extended it to variable intensity sources (typical for FELs), and used it to fit a complex pileup spectrum. We subsequently developed a Bayesian pile-up decomposition method that allows decomposing pile-up of single events with up to six photons from six monochromatic lines with 99% accuracy. The usefulness of SDDs will continue into the X-ray FEL era of science. Their successors, the ePixS hybrid pixel detectors, already offer hundreds of pixels, each with a similar performance to an SDD, in a compact, robust and affordable package.« less

Optimal Pulse Processing, Pile-Up Decomposition, and Applications of Silicon Drift Detectors at LCLS

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

Blaj, G.; Kenney, C. J.; Dragone, A.

Silicon drift detectors (SDDs) revolutionized spectroscopy in fields as diverse as geology and dentistry. For a subset of experiments at ultrafast, X-ray free-electron lasers (FELs), SDDs can make substantial contributions. Often the unknown spectrum is interesting, carrying science data, or the background measurement is useful to identify unexpected signals. Many measurements involve only several discrete photon energies known a priori, allowing single-event decomposition of pile-up and spectroscopic photon counting. We designed a pulse function and demonstrated that the signal amplitude (i.e., proportional to the detected energy and obtained from fitting with the pulse function), rise time, and pulse height aremore » interrelated, and at short peaking times, the pulse height and pulse area are not optimal estimators for detected energy; instead, the signal amplitude and rise time are obtained for each pulse by fitting, thus removing the need for pulse shaping. By avoiding pulse shaping, rise times of tens of nanoseconds resulted in reduced pulse pile-up and allowed decomposition of remaining pulse pile-up at photon separation times down to hundreds of nanoseconds while yielding time-of-arrival information with the precision of 10 ns. Waveform fitting yields simultaneously high energy resolution and high counting rates (two orders of magnitude higher than current digital pulse processors). At pulsed sources or high photon rates, photon pile-up still occurs. We showed that pile-up spectrum fitting is relatively simple and preferable to pile-up spectrum deconvolution. We then developed a photon pile-up statistical model for constant intensity sources, extended it to variable intensity sources (typical for FELs), and used it to fit a complex pileup spectrum. We subsequently developed a Bayesian pile-up decomposition method that allows decomposing pile-up of single events with up to six photons from six monochromatic lines with 99% accuracy. The usefulness of SDDs will continue into the X-ray FEL era of science. Their successors, the ePixS hybrid pixel detectors, already offer hundreds of pixels, each with a similar performance to an SDD, in a compact, robust and affordable package.« less

Radioanalytical Chemistry for Automated Nuclear Waste Process Monitoring

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

Devol, Timothy A.

2005-06-01

Comparison of different pulse shape discrimination methods was performed under two different experimental conditions and the best method was identified. Beta/gamma discrimination of 90Sr/90Y and 137Cs was performed using a phoswich detector made of BC400 (2.5 cm OD x 1.2 cm) and BGO (2.5 cm O.D. x 2.5 cm ) scintillators. Alpha/gamma discrimination of 210Po and 137Cs was performed using a CsI:Tl (2.8 x 1.4 x 1.4 cm3) scintillation crystal. The pulse waveforms were digitized with a DGF-4c (X-Ray Instrumentation Associates) and analyzed offline with IGOR Pro software (Wavemetrics, Inc.). The four pulse shape discrimination methods that were compared include:more » rise time discrimination, digital constant fraction discrimination, charge ratio, and constant time discrimination (CTD) methods. The CTD method is the ratio of the pulse height at a particular time after the beginning of the pulse to the time at the maximum pulse height. The charge comparison method resulted in a Figure of Merit (FoM) of 3.3 (9.9 % spillover) and 3.7 (0.033 % spillover) for the phoswich and the CsI:Tl scintillator setups, respectively. The CTD method resulted in a FoM of 3.9 (9.2 % spillover) and 3.2 (0.25 % spillover), respectively. Inverting the pulse shape data typically resulted in a significantly higher FoM than conventional methods, but there was no reduction in % spillover values. This outcome illustrates that the FoM may not be a good scheme for the quantification of a system to perform pulse shape discrimination. Comparison of several pulse shape discrimination (PSD) methods was performed as a means to compare traditional analog and digital PSD methods on the same scintillation pulses. The X-ray Instrumentation Associates DGF-4C (40 Msps, 14-bit) was used to digitize waveforms from a CsI:Tl crystal and BC400/BGO phoswich detector.« less

Forest Resource Measurements by Combination of Terrestrial Laser Scanning and Drone Use

NASA Astrophysics Data System (ADS)

Cheung, K.; Katoh, M.; Horisawa, M.

2017-10-01

Using terrestrial laser scanning (TLS), forest attributes such as diameter at breast height (DBH) and tree location can be measured accurately. However, due to low penetration of laser pulses to tree tops, tree height measurements are typically underestimated. In this study, data acquired by TLS and drones were combined; DBH and tree locations were determined by TLS, and tree heights were measured by drone use. The average tree height error and root mean square error (RMSE) of tree height were 0.8 and 1.2 m, respectively, for the combined method, and -0.4 and 1.7 m using TLS alone. The tree height difference was compared using airborne laser scanning (ALS). Furthermore, a method to acquire 100 % tree detection rate based on TLS data is suggested in this study.

Effects of blood pressure and sex on the change of wave reflection: evidence from Gaussian fitting method for radial artery pressure waveform.

PubMed

Liu, Chengyu; Zhao, Lina; Liu, Changchun

2014-01-01

An early return of the reflected component in the arterial pulse has been recognized as an important indicator of cardiovascular risk. This study aimed to determine the effects of blood pressure and sex factor on the change of wave reflection using Gaussian fitting method. One hundred and ninety subjects were enrolled. They were classified into four blood pressure categories based on the systolic blood pressures (i.e., ≤ 110, 111-120, 121-130 and ≥ 131 mmHg). Each blood pressure category was also stratified for sex factor. Electrocardiogram (ECG) and radial artery pressure waveforms (RAPW) signals were recorded for each subject. Ten consecutive pulse episodes from the RAPW signal were extracted and normalized. Each normalized pulse episode was fitted by three Gaussian functions. Both the peak position and peak height of the first and second Gaussian functions, as well as the peak position interval and peak height ratio, were used as the evaluation indices of wave reflection. Two-way ANOVA results showed that with the increased blood pressure, the peak position of the second Gaussian significantly shorten (P < 0.01), the peak height of the first Gaussian significantly decreased (P < 0.01) and the peak height of the second Gaussian significantly increased (P < 0.01), inducing the significantly decreased peak position interval and significantly increased peak height ratio (both P < 0.01). Sex factor had no significant effect on all evaluation indices (all P > 0.05). Moreover, the interaction between sex and blood pressure factors also had no significant effect on all evaluation indices (all P > 0.05). These results showed that blood pressure has significant effect on the change of wave reflection when using the recently developed Gaussian fitting method, whereas sex has no significant effect. The results also suggested that the Gaussian fitting method could be used as a new approach for assessing the arterial wave reflection.

Impact of intense x-ray pulses on a NaI(Tl)-based gamma camera

NASA Astrophysics Data System (ADS)

Koppert, W. J. C.; van der Velden, S.; Steenbergen, J. H. L.; de Jong, H. W. A. M.

2018-03-01

In SPECT/CT systems x-ray and γ-ray imaging is performed sequentially. Simultaneous acquisition may have advantages, for instance in interventional settings. However, this may expose a gamma camera to relatively high x-ray doses and deteriorate its functioning. We studied the NaI(Tl) response to x-ray pulses with a photodiode, PMT and gamma camera, respectively. First, we exposed a NaI(Tl)-photodiode assembly to x-ray pulses to investigate potential crystal afterglow. Next, we exposed a NaI(Tl)-PMT assembly to 10 ms LED pulses (mimicking x-ray pulses) and measured the response to flashing LED probe-pulses (mimicking γ-pulses). We then exposed the assembly to x-ray pulses, with detector entrance doses of up to 9 nGy/pulse, and analysed the response for γ-pulse variations. Finally, we studied the response of a Siemens Diacam gamma camera to γ-rays while exposed to x-ray pulses. X-ray exposure of the crystal, read out with a photodiode, revealed 15% afterglow fraction after 3 ms. The NaI(Tl)-PMT assembly showed disturbances up to 10 ms after 10 ms LED exposure. After x-ray exposure however, responses showed elevated baselines, with 60 ms decay-time. Both for x-ray and LED exposure and after baseline subtraction, probe-pulse analysis revealed disturbed pulse height measurements shortly after exposure. X-ray exposure of the Diacam corroborated the elementary experiments. Up to 50 ms after an x-ray pulse, no events are registered, followed by apparent energy elevations up to 100 ms after exposure. Limiting the dose to 0.02 nGy/pulse prevents detrimental effects. Conventional gamma cameras exhibit substantial dead-time and mis-registration of photon energies up to 100 ms after intense x-ray pulses. This is due PMT limitations and due to afterglow in the crystal. Using PMTs with modified circuitry, we show that deteriorative afterglow effects can be reduced without noticeable effects on the PMT performance, up to x-ray pulse doses of 1 nGy.

Temporal femtosecond pulse shaping dependence of laser-induced periodic surface structures in fused silica

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

Shi, Xuesong; Jiang, Lan; Li, Xin, E-mail: lixin02@bit.edu.cn

2014-07-21

The dependence of periodic structures and ablated areas on temporal pulse shaping is studied upon irradiation of fused silica by femtosecond laser triple-pulse trains. Three types of periodic structures can be obtained by using pulse trains with designed pulse delays, in which the three-dimensional nanopillar arrays with ∼100–150 nm diameters and ∼200 nm heights are first fabricated in one step. These nanopillars arise from the break of the ridges of ripples in the upper portion, which is caused by the split of orthogonal ripples in the bottom part. The localized transient electron dynamics and corresponding material properties are considered for the morphologicalmore » observations.« less

Fractional channel multichannel analyzer

DOEpatents

Brackenbush, L.W.; Anderson, G.A.

1994-08-23

A multichannel analyzer incorporating the features of the present invention obtains the effect of fractional channels thus greatly reducing the number of actual channels necessary to record complex line spectra. This is accomplished by using an analog-to-digital converter in the asynchronous mode, i.e., the gate pulse from the pulse height-to-pulse width converter is not synchronized with the signal from a clock oscillator. This saves power and reduces the number of components required on the board to achieve the effect of radically expanding the number of channels without changing the circuit board. 9 figs.

Fractional channel multichannel analyzer

DOEpatents

Brackenbush, Larry W.; Anderson, Gordon A.

1994-01-01

A multichannel analyzer incorporating the features of the present invention obtains the effect of fractional channels thus greatly reducing the number of actual channels necessary to record complex line spectra. This is accomplished by using an analog-to-digital converter in the asynscronous mode, i.e., the gate pulse from the pulse height-to-pulse width converter is not synchronized with the signal from a clock oscillator. This saves power and reduces the number of components required on the board to achieve the effect of radically expanding the number of channels without changing the circuit board.

Data acquisition system for phase-2 KGF proton decay experiment

NASA Technical Reports Server (NTRS)

Krishnaswamy, M. R.; Menon, M. G. K.; Mondal, N. K.; Narasimham, V. S.; Sreekantan, B. V.; Hayashi, Y.; Ito, N.; Kawakami, S.; Miyake, S.

1985-01-01

Phase-2 of KGF proton decay experiment using 4000 proportional counters will start operating from middle of 1985. The detection systems, in addition to measuring the time information to an accuracy of 200 n see, also records ionization in the hit counters. It also monitors different characteristics of the counters like pulse height spectrum, pulse width spectrum and counting rate. The acquisition system is discussed.

Development of a compact and cost effective multi-input digital signal processing system

NASA Astrophysics Data System (ADS)

Darvish-Molla, Sahar; Chin, Kenrick; Prestwich, William V.; Byun, Soo Hyun

2018-01-01

A prototype digital signal processing system (DSP) was developed using a microcontroller interfaced with a 12-bit sampling ADC, which offers a considerably inexpensive solution for processing multiple detectors with high throughput. After digitization of the incoming pulses, in order to maximize the output counting rate, a simple algorithm was employed for pulse height analysis. Moreover, an algorithm aiming at the real-time pulse pile-up deconvolution was implemented. The system was tested using a NaI(Tl) detector in comparison with a traditional analogue and commercial digital systems for a variety of count rates. The performance of the prototype system was consistently superior to the analogue and the commercial digital systems up to the input count rate of 61 kcps while was slightly inferior to the commercial digital system but still superior to the analogue system in the higher input rates. Considering overall cost, size and flexibility, this custom made multi-input digital signal processing system (MMI-DSP) was the best reliable choice for the purpose of the 2D microdosimetric data collection, or for any measurement in which simultaneous multi-data collection is required.

SPE analysis of high efficiency PMTs for the DEAP-3600 dark matter detector

NASA Astrophysics Data System (ADS)

Olsen, Kevin; Hallin, Aksel; DEAP/CLEAN Collaboration

2011-09-01

The Dark matter Experiment using Argon Pulse-shape discrimination is a collaborative effort to develop a next-generation, tonne-scale dark matter detector at SNOLAB. The detector will feature a single-phase liquid argon (LAr) target surrounded by an array of 266 photomultiplier tubes (PMTs). A new high-efficiency Hamamatsu R877-100 PMT has been delivered to the University of Alberta for evaluation by the DEAP collaboration. The increase in efficiency could lead to a much greater light yield, but other experiments have reported a slower rise time [1],[2]. We have placed the PMT in a small dark box and had a base and preamplifier designed to be used with either an oscilloscope or a multi-channel analyzer. With this setup we have demonstrated the PMT's ability to distinguish single photo-electrons (SPE) and characterized the PMT by measuring the SPE pulse height spectrum, the peak-to-valley ratio, the dark pulse rate, the baseline, time resolution and SPE efficiency for varying the high voltage supplied to the PMT.

Spatial structure of the arc in a pulsed GMAW process

NASA Astrophysics Data System (ADS)

Kozakov, R.; Gött, G.; Schöpp, H.; Uhrlandt, D.; Schnick, M.; Häßler, M.; Füssel, U.; Rose, S.

2013-06-01

A pulsed gas metal arc welding (GMAW) process of steel under argon shielding gas in the globular mode is investigated by measurements and simulation. The analysis is focussed on the spatial structure of the arc during the current pulse. Therefore, the radial profiles of the temperature, the metal vapour species and the electric conductivity are determined at different heights above the workpiece by optical emission spectroscopy (OES). It is shown that under the presence of metal vapour the temperature minimum occurs at the centre of the arc. This minimum is preserved at different axial positions up to 1 mm above the workpiece. In addition, estimations of the electric field in the arc from the measurements are given. All these results are compared with magneto-hydrodynamic simulations which include the evaporation of the wire material and the change of the plasma properties due to the metal vapour admixture in particular. The experimental method and the simulation model are validated by means of the satisfactory correspondence between the results. Possible reasons for the remaining deviations and improvements of the methods which should be aspired are discussed.

Full-Time, Eye-Safe Cloud and Aerosol Lidar Observation at Atmospheric Radiation Measurement Program Sites: Instruments and Data Analysis

NASA Technical Reports Server (NTRS)

Campbell, James R.; Hlavka, Dennis L.; Welton, Ellsworth J.; Flynn, Connor J.; Turner, David D.; Spinhirne, James D.; Scott, V. Stanley, III; Hwang, I. H.; Einaudi, Franco (Technical Monitor)

2001-01-01

Atmospheric radiative forcing, surface radiation budget, and top of the atmosphere radiance interpretation involves a knowledge of the vertical height structure of overlying cloud and aerosol layers. During the last decade, the U.S. Department of Energy through I the Atmospheric Radiation Measurement (ARM) program has constructed four long- term atmospheric observing sites in strategic climate regimes (north central Oklahoma, In Barrow. Alaska, and Nauru and Manus Islands in the tropical western Pacific). Micro Pulse Lidar (MPL) systems provide continuous, autonomous observation of all significant atmospheric cloud and aerosol at each of the central ARM facilities. Systems are compact and transmitted pulses are eye-safe. Eye-safety is achieved by expanding relatively low-powered outgoing Pulse energy through a shared, coaxial transmit/receive telescope. ARM NIPL system specifications, and specific unit optical designs are discussed. Data normalization and calibration techniques are presented. A multiple cloud boundary detection algorithm is also described. These techniques in tandem represent an operational value added processing package used to produce normalized data products for Cloud and aerosol research and the historical ARM data archive.

Autonomous, Full-Time Cloud Profiling at Arm Sites with Micro Pulse Lidar

NASA Technical Reports Server (NTRS)

Spinhirne, James D.; Campbell, James R.; Hlavka, Dennis L.; Scott, V. Stanley; Flynn, Connor J.

2000-01-01

Since the early 1990's technology advances permit ground based lidar to operate full time and profile all significant aerosol and cloud structure of the atmosphere up to the limit of signal attenuation. These systems are known as Micro Pulse Lidars (MPL), as referenced by Spinhirne (1993), and were first in operation at DOE Atmospheric Radiation Measurement (ARM) sites. The objective of the ARM program is to improve the predictability of climate change, particularly as it relates to cloud-climate feedback. The fundamental application of the MPL systems is towards the detection of all significant hydrometeor layers, to the limit of signal attenuation. The heating and cooling of the atmosphere are effected by the distribution and characteristics of clouds and aerosol concentration. Aerosol and cloud retrievals in several important areas can only be adequately obtained with active remote sensing by lidar. For cloud cover, the height and related emissivity of thin clouds and the distribution of base height for all clouds are basic parameters for the surface radiation budget, and lidar is essetial for accurate measurements. The ARM MPL observing network represents the first long-term, global lidar study known within the community. MPL systems are now operational at four ARM sites. A six year data set has been obtained at the original Oklahoma site, and there are several years of observations at tropical and artic sites. Observational results include cloud base height distributions and aerosol profiles. These expanding data sets offer a significant new resource for cloud, aerosol and atmospheric radiation analysis. The nature of the data sets, data processing algorithms, derived parameters and application results are presented.

Reference intervals and percentiles for carotid-femoral pulse wave velocity in a healthy population aged between 9 and 87 years.

PubMed

Diaz, Alejandro; Zócalo, Yanina; Bia, Daniel; Wray, Sandra; Fischer, Edmundo Cabrera

2018-04-01

There is little information regarding age-related reference intervals (RIs) of carotid-femoral pulse wave velocity (cfPWV) for large healthy populations in South America. The aims of this study were to determine cfPWV RIs and percentiles in a cohort of healthy children, adolescents, and adults and to generate year-to-year percentile curves and body-height percentile curves for children and adolescents. cfPWV was measured in 1722 healthy participants with no cardiovascular risk factors (9-87 years, 60% men). First, RIs were evaluated for males and females through correlation and covariate analysis. Then, mean and standard deviation age-related equations were obtained for cfPWV using parametric regression methods based on fractional polynomials and age-specific (year-to-year) percentile curves that were defined using the standard normal distribution. Age-specific first, 2.5th, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97.5th, and 99th percentile curves were calculated. Finally, height-related cfPWV percentile curves for children and adolescents (<21 years) were established. After adjusting for age and blood pressure differences with respect to females, males showed higher cfPWV levels (6.60 vs 6.45 m/s; P < .01). Thus, specific RIs for males and females were reported. The study provides the largest database to date concerning cfPWV in healthy people from Argentina. Specific RIs and percentiles of cfPWV are now available according to age and sex. Specific percentiles of cfPWV according to body height were reported for people younger than 21 years. ©2018 Wiley Periodicals, Inc.

Doppler indexes of left ventricular systolic and diastolic flow and central pulse pressure in relation to renal resistive index.

PubMed

Kuznetsova, Tatiana; Cauwenberghs, Nicholas; Knez, Judita; Thijs, Lutgarde; Liu, Yan-Ping; Gu, Yu-Mei; Staessen, Jan A

2015-04-01

The cardio-renal interaction occurs via hemodynamic and humoral factors. Noninvasive assessment of renal hemodynamics is currently possible by assessment of renal resistive index (RRI) derived from intrarenal Doppler arterial waveforms as ((peak systolic velocity - end-diastolic velocity)/peak systolic velocity). Limited information is available regarding the relationship between RRI and cardiac hemodynamics. We investigated these associations in randomly recruited subjects from a general population. In 171 participants (48.5% women; mean age, 52.2 years), using pulsed wave Doppler, we measured RRI (mean, 0.60) and left ventricular outflow tract (LVOT) and transmitral (E and A) blood flow peak velocities and its velocity time integrals (VTI). Using carotid applanation tonometry, we measured central pulse pressure and arterial stiffness indexes such as augmentation pressure and carotid-femoral pulse wave velocity. In stepwise regression analysis, RRI independently and significantly increased with female sex, age, body weight, brachial pulse pressure, and use of β-blockers, whereas it decreased with body height and mean arterial pressure. In multivariable-adjusted models with central pulse pressure and arterial stiffness indexes as the explanatory variables, we observed a significant and positive correlation of RRI only with central pulse pressure (P < 0.0001). Among the Doppler indexes of left ventricular blood flow, RRI was significantly and positively associated with LVOT and E peak velocities (P ≤ 0.012) and VTIs (P ≤ 0.010). We demonstrated that in unselected subjects RRI was significantly associated with central pulse pressure and left ventricular systolic and diastolic Doppler blood flow indexes. Our findings imply that in addition to the anthropometric characteristics, cardiac hemodynamic factors influence the intrarenal arterial Doppler waveform patterns. © American Journal of Hypertension, Ltd 2014. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Development of multichannel analyzer using sound card ADC for nuclear spectroscopy system

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

Ibrahim, Maslina Mohd; Yussup, Nolida; Lombigit, Lojius

This paper describes the development of Multi-Channel Analyzer (MCA) using sound card analogue to digital converter (ADC) for nuclear spectroscopy system. The system was divided into a hardware module and a software module. Hardware module consist of detector NaI (Tl) 2” by 2”, Pulse Shaping Amplifier (PSA) and a build in ADC chip from readily available in any computers’ sound system. The software module is divided into two parts which are a pre-processing of raw digital input and the development of the MCA software. Band-pass filter and baseline stabilization and correction were implemented for the pre-processing. For the MCA development,more » the pulse height analysis method was used to process the signal before displaying it using histogram technique. The development and tested result for using the sound card as an MCA are discussed.« less

Two-dimensional dissipative rogue waves due to time-delayed feedback in cavity nonlinear optics.

PubMed

Tlidi, Mustapha; Panajotov, Krassimir

2017-01-01

We demonstrate a way to generate two-dimensional rogue waves in two types of broad area nonlinear optical systems subject to time-delayed feedback: in the generic Lugiato-Lefever model and in the model of a broad-area surface-emitting laser with saturable absorber. The delayed feedback is found to induce a spontaneous formation of rogue waves. In the absence of delayed feedback, spatial pulses are stationary. The rogue waves are exited and controlled by the delay feedback. We characterize their formation by computing the probability distribution of the pulse height. The long-tailed statistical contribution, which is often considered as a signature of the presence of rogue waves, appears for sufficiently strong feedback. The generality of our analysis suggests that the feedback induced instability leading to the spontaneous formation of two-dimensional rogue waves is a universal phenomenon.

Measurement of x-ray spectra using a recent YAP(Ce)-MPPC detector

NASA Astrophysics Data System (ADS)

Sato, Eiichi; Oda, Yasuyuki; Yoshida, Sohei; Yamaguchi, Satoshi; Sato, Yuichi; Ishii, Tomotaka; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya

2017-09-01

To measure X-ray spectra with high count rates, we developed a detector consisting of a cerium-doped yttrium aluminum perovskite [YAP(Ce)] crystal and a recent multipixel photon counter (MPPC). Scintillation photons are detected using the MPPC, and the photocurrents flowing through the MPPC are converted into voltages and amplified using a high-speed current-voltage (I-V) amplifier. The MPPC bias voltage was set to a value at the pre-Geiger mode to perform zero-dark counting. The event-pulse widths were approximately 200 ns, and the widths were extend to approximately 1 μs. X-ray spectra were measured using a multichannel analyzer (MCA) for pulse-height analysis. The photon energy was roughly determined by the two-point calibration using tungsten K photons and iodine K fluorescence. Using the YAP(Ce)-MPPC detector, first-generation dual-energy computed tomography was accomplished using iodine and gadolinium contrast media.

Energy Calibration of a Silicon-Strip Detector for Photon-Counting Spectral CT by Direct Usage of the X-ray Tube Spectrum

NASA Astrophysics Data System (ADS)

Liu, Xuejin; Chen, Han; Bornefalk, Hans; Danielsson, Mats; Karlsson, Staffan; Persson, Mats; Xu, Cheng; Huber, Ben

2015-02-01

The variation among energy thresholds in a multibin detector for photon-counting spectral CT can lead to ring artefacts in the reconstructed images. Calibration of the energy thresholds can be used to achieve homogeneous threshold settings or to develop compensation methods to reduce the artefacts. We have developed an energy-calibration method for the different comparator thresholds employed in a photon-counting silicon-strip detector. In our case, this corresponds to specifying the linear relation between the threshold positions in units of mV and the actual deposited photon energies in units of keV. This relation is determined by gain and offset values that differ for different detector channels due to variations in the manufacturing process. Typically, the calibration is accomplished by correlating the peak positions of obtained pulse-height spectra to known photon energies, e.g. with the aid of mono-energetic x rays from synchrotron radiation, radioactive isotopes or fluorescence materials. Instead of mono-energetic x rays, the calibration method presented in this paper makes use of a broad x-ray spectrum provided by commercial x-ray tubes. Gain and offset as the calibration parameters are obtained by a regression analysis that adjusts a simulated spectrum of deposited energies to a measured pulse-height spectrum. Besides the basic photon interactions such as Rayleigh scattering, Compton scattering and photo-electric absorption, the simulation takes into account the effect of pulse pileup, charge sharing and the electronic noise of the detector channels. We verify the method for different detector channels with the aid of a table-top setup, where we find the uncertainty of the keV-value of a calibrated threshold to be between 0.1 and 0.2 keV.

The Microwave Spectrum of Methyl Vinyl Ketone Revisited

NASA Astrophysics Data System (ADS)

Wilcox, David S.; Shirar, Amanda J.; Williams, Owen L.; Dian, Brian C.

2011-06-01

A chirped-pulse Fourier transform microwave spectrometer was used to record the rotational spectrum of methyl vinyl ketone (MVK, 3-butene-2-one) from 6 to 18.9 GHz. Two stable conformations were identified: the previously documented antiperiplanar (ap) conformer and synperiplanar (sp), which is reported for the first time in this microwave study. Methyl torsional analysis with XIAM resulted in V3 barrier heights of 433.8(1) and 376.6(2) Cm-1 for ap- and sp-MVK, respectively. Heavy atom isotopic species were detected in natural abundance allowing bond lengths and angles of the molecular frames to be calculated through Kraitchman analysis. A comparison with ab initio calculations is included.

A photon-counting photodiode array detector for far ultraviolet (FUV) astronomy

NASA Technical Reports Server (NTRS)

Hartig, G. F.; Moos, H. W.; Pembroke, R.; Bowers, C.

1982-01-01

A compact, stable, single-stage intensified photodiode array detector designed for photon-counting, far ultraviolet astronomy applications employs a saturable, 'C'-type MCP (Galileo S. MCP 25-25) to produce high gain pulses with a narrowly peaked pulse height distribution. The P-20 output phosphor exhibits a very short decay time, due to the high current density of the electron pulses. This intensifier is being coupled to a self-scanning linear photodiode array which has a fiber optic input window which allows direct, rigid mechanical coupling with minimal light loss. The array was scanned at a 250 KHz pixel rate. The detector exhibits more than adequate signal-to-noise ratio for pulse counting and event location.

Little Boy neutron spectrum below 1 MeV

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

Evans, A.E.

1984-01-01

A high-resolution /sup 3/He ionization chamber of the type development by Cuttler and Shalev was used to study the neutron spectrum from the Little Boy mockup. Measurements were made at distances of 0.75 and 2.0 m and at angles of 0/sup 0/, 45/sup 0/, and 90/sup 0/ with respect to the axis of the assembly, which was operated at power levels from 8.6 to 450 mW. Detector efficiency as a function of energy as well as parameters for correction of pulse-height distributions for proton-recoil and wall effects were determined from a set of response functions for monoenergetic neutrons measured atmore » the Los Alamos 3.75-MeV Van de Graaff Accelerator Facility. Pulse-shape discrimination was used to separate /sup 3/He-recoil pulses from the pulse-height distribution. The spectrum was found to be highly structured, with peaks corresponding to minima in the total neutron cross section of iron. In particular, 15% of the neutrons above the epithermal peak in energy were found to be in the 24-keV iron window. Lesser peaks out to 700 keV are also attributable to filtering action of the weapon's heavy iron casing. Data taken using experimental proton-recoil proportional counters are compared with the high-resolution spectra.« less

An experimental investigation of using carbon foam-PCM-MWCNTs composite materials for thermal management of electronic devices under pulsed power modes

NASA Astrophysics Data System (ADS)

Alshaer, W. G.; Rady, M. A.; Nada, S. A.; Palomo Del Barrio, Elena; Sommier, Alain

2017-02-01

The present article reports on a detailed experimental investigation of using carbon foam-PCM-MWCNTs composite materials for thermal management (TM) of electronic devices subjected to pulsed power. The TM module was fabricated by infiltrating paraffin wax (RT65) as a phase change material (PCM) and multi walled carbon nanotubes (MWCNTs) as a thermal conductivity enhancer in a carbon foam as a base structure. Two carbon foam materials of low and high values of thermal conductivities, CF20 and KL1-250 (3.1 and 40 W/m K), were tested as a base structure for the TM modules. Tests were conducted at different power intensities and power cycling/loading modes. Results showed that for all power varying modes and all carbon foams, the infiltration of RT65 into carbon foam reduces the temperature of TM module and results in damping the temperature spikes height. Infiltration of MWCNTS into RT65 further improves the effectiveness of TM module. Temperature damping was more pronounced in stand-alone pulsed power cycles as compared to pulsed power spikes modes. The effectiveness of inclusion of RT65 and RT65/MWCNTs in damping the temperature spikes height is remarkable in TM modules based on KL1-250 as compared to CF-20.

The possibility of multi-layer nanofabrication via atomic force microscope-based pulse electrochemical nanopatterning

NASA Astrophysics Data System (ADS)

Kim, Uk Su; Morita, Noboru; Lee, Deug Woo; Jun, Martin; Park, Jeong Woo

2017-05-01

Pulse electrochemical nanopatterning, a non-contact scanning probe lithography process using ultrashort voltage pulses, is based primarily on an electrochemical machining process using localized electrochemical oxidation between a sharp tool tip and the sample surface. In this study, nanoscale oxide patterns were formed on silicon Si (100) wafer surfaces via electrochemical surface nanopatterning, by supplying external pulsed currents through non-contact atomic force microscopy. Nanoscale oxide width and height were controlled by modulating the applied pulse duration. Additionally, protruding nanoscale oxides were removed completely by simple chemical etching, showing a depressed pattern on the sample substrate surface. Nanoscale two-dimensional oxides, prepared by a localized electrochemical reaction, can be defined easily by controlling physical and electrical variables, before proceeding further to a layer-by-layer nanofabrication process.

Portable x-ray fluorescence spectrometer for environmental monitoring of inorganic pollutants

NASA Technical Reports Server (NTRS)

Clark, III, Benton C. (Inventor); Thornton, Michael G. (Inventor)

1991-01-01

A portable x-ray fluorescence spectrometer has a portable sensor unit containing a battery, a high voltage power supply, an x-ray tube which produces a beam x-ray radiation directed toward a target sample, and a detector for fluorescent x-rays produced by the sample. If a silicon-lithium detector is used, the sensor unit also contains either a thermoelectric or thermochemical cooler, or a small dewar flask containing liquid nitrogen to cool the detector. A pulse height analyzer (PHA) generates a spectrum of data for each sample consisting of the number of fluorescent x-rays detected as a function of their energy level. The PHA can also store spectrum data for a number of samples in the field. A processing unit can be attached to the pulse height analyzer to upload and analyze the stored spectrum data for each sample. The processing unit provides a graphic display of the spectrum data for each sample, and provides qualitative and/or quantitative analysis of the elemental composition of the sample by comparing the peaks in the sample spectrum against known x-ray energies for various chemical elements. An optional filtration enclosure can be used to filter particles from a sample suspension, either in the form of a natural suspension or a chemically created precipitate. The sensor unit is then temporarily attached to the filtration unit to analyze the particles collected by the filter medium.

Effect of annealing temperature on the photoluminescence and scintillation properties of ZnO nanorods

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

Kurudirek, Sinem V.; Menkara, H.; Klein, Benjamin D. B.

2018-01-01

The effect of the annealing to enhance the photoluminescence (PL) and scintillation properties, as determined by pulse height distribution of alpha particle irradiation, has been investigated for solution grown ZnO nanorods For this investigation the ZnO nanorod arrays were grown on glass for 22 h at 95 ◦ C as a substrate using a solution based hydrothermal technique. The samples were first annealed for different times (30, 60, 90 and 120 min) at 300 ◦ C and then at different temperatures (100 ◦ C–600 ◦ C) in order to determine the optimum annealing time and temperature, respectively. Before annealing, themore » ZnO nanorod arrays showed a broad yellow–orange visible and near-band gap UV emission peaks. After annealing in a forming gas atmosphere, the intensity of the sub-band gap PL was significantly reduced and the near-band gap PL emission intensity correspondingly increased (especially at temperatures higher than 100 ◦ C). Based on the ratio of the peak intensity ratio before and after annealing, it was concluded that samples at 350 ◦ C for 90 min resulted in the best near-band gap PL emission. Similarly, the analysis of the pulse height spectrum resulting from alpha particles revealed that ZnO nanorod arrays similarly annealed at 350 ◦ C for 90 min exhibited the highest scintillation response.« less

Digital Photoplethysmography for Assessment of Arterial Stiffness: Repeatability and Comparison with Applanation Tonometry

PubMed Central

Östling, Gerd; Nilsson, Peter M.

2015-01-01

Introduction Arterial stiffness is an independent risk factor for cardiovascular morbidity and can be assessed by applanation tonometry by measuring pulse wave velocity (PWV) and augmentation index (AIX) by pressure pulse wave analysis (PWA). As an inexpensive and operator independent alternative, photoelectric plethysmography (PPG) has been introduced with analysis of the digital volume pulse wave (DPA) and its second derivatives of wave reflections. Objective The objective was to investigate the repeatability of arterial stiffness parameters measured by digital pulse wave analysis (DPA) and the associations to applanation tonometry parameters. Methods and Results 112 pregnant and non-pregnant individuals of different ages and genders were examined with SphygmoCor arterial wall tonometry and Meridian DPA finger photoplethysmography. Coefficients of repeatability, Bland-Altman plots, intraclass correlation coefficients and correlations to heart rate (HR) and body height were calculated for DPA variables, and the DPA variables were compared to tonometry variables left ventricular ejection time (LVET), PWV and AIX. No DPA variable showed any systematic measurement error or excellent repeatability, but dicrotic index (DI), dicrotic dilatation index (DDI), cardiac ejection elasticity index (EEI), aging index (AI) and second derivatives of the crude pulse wave curve, b/a and e/a, showed good repeatability. Overall, the correlations to AIX were better than to PWV, with correlations coefficients >0.70 for EEI, AI and b/a. Considering the level of repeatability and the correlations to tonometry, the overall best DPA parameters were EEI, AI and b/a. The two pansystolic time parameters, ejection time compensated (ETc) by DPA and LVET by tonometry, showed a significant but weak correlation. Conclusion For estimation of the LV function, ETc, EEI and b/a are suitable, for large artery stiffness EEI, and for small arteries DI and DDI. The only global parameter, AI, showed a high repeatability and the overall best correlations with AIX and PWV. PMID:26291079

Improved neutron-gamma discrimination for a 3He neutron detector using subspace learning methods

DOE PAGES

Wang, C. L.; Funk, L. L.; Riedel, R. A.; ...

2017-02-10

3He gas based neutron linear-position-sensitive detectors (LPSDs) have been applied for many neutron scattering instruments. Traditional Pulse-Height Analysis (PHA) for Neutron-Gamma Discrimination (NGD) resulted in the neutron-gamma efficiency ratio on the orders of 10 5-10 6. The NGD ratios of 3He detectors need to be improved for even better scientific results from neutron scattering. Digital Signal Processing (DSP) analyses of waveforms were proposed for obtaining better NGD ratios, based on features extracted from rise-time, pulse amplitude, charge integration, a simplified Wiener filter, and the cross-correlation between individual and template waveforms of neutron and gamma events. Fisher linear discriminant analysis (FLDA)more » and three multivariate analyses (MVAs) of the features were performed. The NGD ratios are improved by about 10 2-10 3 times compared with the traditional PHA method. Finally, our results indicate the NGD capabilities of 3He tube detectors can be significantly improved with subspace-learning based methods, which may result in a reduced data-collection time and better data quality for further data reduction.« less

Lithium and boron based semiconductors for thermal neutron counting

NASA Astrophysics Data System (ADS)

Kargar, Alireza; Tower, Joshua; Hong, Huicong; Cirignano, Leonard; Higgins, William; Shah, Kanai

2011-09-01

Thermal neutron detectors in planar configuration were fabricated from LiInSe2 and B2Se3 crystals grown at RMD Inc. All fabricated semiconductor devices were characterized for the current-voltage (I-V) characteristic and neutron counting measurement. Pulse height spectra were collected from 241AmBe (neutron source on all samples), as well as 137Cs and 60Co gamma ray sources. In this study, the resistivity of all crystals is reported and the collected pulse height spectra are presented for fabricated devices. Note that, the 241AmBe neutron source was custom designed with polyethylene around the source as the neutron moderator, mainly to thermalize the fast neutrons before reaching the detectors. Both LiInSe2 and B2Se3 devices showed response to thermal neutrons of the 241AmBe source.

Mass-dependent channel electron multiplier operation. [for ion detection

NASA Technical Reports Server (NTRS)

Fields, S. A.; Burch, J. L.; Oran, W. A.

1977-01-01

The absolute counting efficiency and pulse height distributions of a continuous-channel electron multiplier used in the detection of hydrogen, argon and xenon ions are assessed. The assessment technique, which involves the post-acceleration of 8-eV ion beams to energies from 100 to 4000 eV, provides information on counting efficiency versus post-acceleration voltage characteristics over a wide range of ion mass. The charge pulse height distributions for H2 (+), A (+) and Xe (+) were measured by operating the experimental apparatus in a marginally gain-saturated mode. It was found that gain saturation occurs at lower channel multiplier operating voltages for light ions such as H2 (+) than for the heavier ions A (+) and Xe (+), suggesting that the technique may be used to discriminate between these two classes of ions in electrostatic analyzers.

Scintillation detector efficiencies for neutrons in the energy region above 20 MeV

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

Dickens, J.K.

1991-01-01

The computer program SCINFUL (for SCINtillator FUL1 response) is a program designed to provide a calculated complete pulse-height response anticipated for neutrons being detected by either an NE-213 (liquid) scintillator or an NE-110 (solid) scintillator in the shape of a right circular cylinder. The point neutron source may be placed at any location with respect to the detector, even inside of it. The neutron source may be monoenergetic, or Maxwellian distributed, or distributed between chosen lower and upper bounds. The calculational method uses Monte Carlo techniques, and it is relativistically correct. Extensive comparisons with a variety of experimental data havemore » been made. There is generally overall good agreement (less than 10% differences) of results for SCINFUL calculations with measured integral detector efficiencies for the design incident neutron energy range of 0.1 to 80 MeV. Calculations of differential detector responses, i.e. yield versus response pulse height, are generally within about 5% on the average for incident neutron energies between 16 and 50 MeV and for the upper 70% of the response pulse height. For incident neutron energies between 50 and 80 MeV, the calculated shape of the response agrees with measurements, but the calculations tend to underpredict the absolute values of the measured responses. Extension of the program to compute responses for incident neutron energies greater than 80 MeV will require new experimental data on neutron interactions with carbon. 32 refs., 6 figs., 2 tabs.« less

Scintillation detector efficiencies for neutrons in the energy region above 20 MeV

NASA Astrophysics Data System (ADS)

Dickens, J. K.

The computer program SCINFUL (for SCINtillator FUL1 response) is a program designed to provide a calculated complete pulse-height response anticipated for neutrons being detected by either an NE-213 (liquid) scintillator or an NE-110 (solid) scintillator in the shape of a right circular cylinder. The point neutron source may be placed at any location with respect to the detector, even inside of it. The neutron source may be monoenergetic, or Maxwellian distributed, or distributed between chosen lower and upper bounds. The calculational method uses Monte Carlo techniques, and it is relativistically correct. Extensive comparisons with a variety of experimental data were made. There is generally overall good agreement (less than 10 pct. differences) of results for SCINFUL calculations with measured integral detector efficiencies for the design incident neutron energy range of 0.1 to 80 MeV. Calculations of differential detector responses, i.e., yield versus response pulse height, are generally within about 5 pct. on the average for incident neutron energies between 16 and 50 MeV and for the upper 70 pct. of the response pulse height. For incident neutron energies between 50 and 80 MeV, the calculated shape of the response agrees with measurements, but the calculations tend to underpredict the absolute values of the measured responses. Extension of the program to compute responses for incident neutron energies greater than 80 MeV will require new experimental data on neutron interactions with carbon.

Square wave voltammetry at the dropping mercury electrode: Experimental

USGS Publications Warehouse

Turner, J.A.; Christie, J.H.; Vukovic, M.; Osteryoung, R.A.

1977-01-01

Experimental verification of earlier theoretical work for square wave voltammetry at the dropping mercury electrode is given. Experiments using ferric oxalate and cadmium(II) in HCl confirm excellent agreement with theory. Experimental peak heights and peak widths are found to be within 2% of calculated results. An example of trace analysis using square wave voltammetry at the DME is presented. The technique is shown to have the same order of sensitivity as differential pulse polarography but is much faster to perform. A detection limit for cadmium in 0.1 M HCl for the system used here was 7 ?? 10-8 M.

Ballistic Deficits for Ionization Chamber Pulses in Pulse Shaping Amplifiers

NASA Astrophysics Data System (ADS)

Kumar, G. Anil; Sharma, S. L.; Choudhury, R. K.

2007-04-01

In order to understand the dependence of the ballistic deficit on the shape of rising portion of the voltage pulse at the input of a pulse shaping amplifier, we have estimated the ballistic deficits for the pulses from a two-electrode parallel plate ionization chamber as well as for the pulses from a gridded parallel plate ionization chamber. These estimations have been made using numerical integration method when the pulses are processed through the CR-RCn (n=1-6) shaping network as well as when the pulses are processed through the complex shaping network of the ORTEC Model 472 spectroscopic amplifier. Further, we have made simulations to see the effect of ballistic deficit on the pulse-height spectra under different conditions. We have also carried out measurements of the ballistic deficits for the pulses from a two-electrode parallel plate ionization chamber as well as for the pulses from a gridded parallel plate ionization chamber when these pulses are processed through the ORTEC 572 linear amplifier having a simple CR-RC shaping network. The reasonable matching of the simulated ballistic deficits with the experimental ballistic deficits for the CR-RC shaping network clearly establishes the validity of the simulation technique

Characterization of Vertical Impact Device Acceleration Pulses Using Parametric Assessment: Phase IV Dual Impact Pulses

DTIC Science & Technology

2017-01-04

response, including the time for reviewing instructions, searching existing data sources, searching existing data sources, gathering and maintaining...configurations with a restrained manikin, was evaluated in four different test series . Test Series 1 was conducted to determine the materials and...5 ms TTP. Test Series 2 was conducted to determine the materials and drop heights required for energy attenuation of the seat pan to generate a 4 m

Counter tube window and X-ray fluorescence analyzer study

NASA Technical Reports Server (NTRS)

Hertel, R.; Holm, M.

1973-01-01

A study was performed to determine the best design tube window and X-ray fluorescence analyzer for quantitative analysis of Venusian dust and condensates. The principal objective of the project was to develop the best counter tube window geometry for the sensing element of the instrument. This included formulation of a mathematical model of the window and optimization of its parameters. The proposed detector and instrument has several important features. The instrument will perform a near real-time analysis of dust in the Venusian atmosphere, and is capable of measuring dust layers less than 1 micron thick. In addition, wide dynamic measurement range will be provided to compensate for extreme variations in count rates. An integral pulse-height analyzer and memory accumulate data and read out spectra for detail computer analysis on the ground.

Photon counting photodiode array detector for far ultraviolet (FUV) astronomy

NASA Technical Reports Server (NTRS)

Hartig, G. F.; Moos, H. W.; Pembroke, R.; Bowers, C.

1982-01-01

A compact, stable, single-stage intensified photodiode array detector designed for photon-counting, far ultraviolet astronomy applications employs a saturable, 'C'-type MCP (Galileo S. MCP 25-25) to produce high gain pulses with a narrowly peaked pulse height distribution. The P-20 output phosphor exhibits a very short decay time, due to the high current density of the electron pulses. This intensifier is being coupled to a self-scanning linear photodiode array which has a fiber optic input window which allows direct, rigid mechanical coupling with minimal light loss. The array was scanned at a 250 KHz pixel rate. The detector exhibits more than adequate signal-to-noise ratio for pulse counting and event location. Previously announced in STAR as N82-19118

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

Sadoulet, B.

The use of drift chambers in the field of high energy physics is reviewed including existing apparatus, plans and dreams. Comments are made especially on low cost large area drift chambers, use of pulse height information and high spatial resolution applications. (auth)

Preliminary Examination of Pulse Shapes From GLAS Ocean Returns

NASA Astrophysics Data System (ADS)

Swift, T. P.; Minster, B.

2003-12-01

We have examined GLAS data collected over the Pacific ocean during the commission phase of the ICESat mission, in an area where sea state is well documented. The data used for this preliminary analysis were acquired during two passes along track 95, on March 18 and 26 of 2003, along the stretch offshore southern California. These dates were chosen for their lack of cloud cover; large (4.0 m) and small (0.7 m) significant wave heights, respectively; and the presence of waves emanating from single distant Pacific storms. Cloud cover may be investigated using MODIS images (http://acdisx.gsfc.nasa.gov/data/dataset/MODIS/), while models of significant wave heights and wave vectors for offshore California are archived by the Coastal Data Information Program (http://cdip.ucsd.edu/cdip_htmls/models.shtml). We find that the shape of deep-ocean GLAS pulse returns is diagnostic of the state of the ocean surface. A calm surface produces near-Gaussian, single-peaked shot returns. In contrast, a rough surface produces blurred shot returns which often feature multiple peaks; these peaks are typically separated by total path lengths on the order of one meter. Gaussian curves fit to rough-water returns are therefore less reliable and lead to greater measurement error; outliers in the ocean surface elevation product are mostly the result of poorly fit low-energy shot returns. Additionally, beat patterns and aliasing artifacts may arise from the sampling of deep-ocean wave trains by GLAS footprints separated by 140m. The apparent wavelength of such patterns depends not only on the wave frequency, but also on the angle between the ICESat ground track and the azimuth of the wave crests. We present a preliminary analysis of such patterns which appears to be consistent with a simple geometrical model.

Development of a portable thermal neutron detector based on a boron rich heterodiode

NASA Astrophysics Data System (ADS)

Tomov, R.; Venn, R.; Owens, A.; Peacock, A.

2008-10-01

Results are presented on the development of a portable detector suitable for detection of individual thermal neutrons. The device is based on direct absorption of neutrons in an absorber film containing 10B. The resultant charge arising from the capture products is detected by a p-n junction partly formed from this absorber and internal to the device. When a small bias voltage is applied (typically a few volts) a current pulse is observed due to the movement of this charge in the electric field of the p-n junction. For each detected neutron the charge pulse height, rise time and time of detection are recorded. Device performance, in terms of efficiency and spectral response, is explored as a function of neutron absorber thickness, geometry and overall diode electrical characteristics and validated against neutron source measurements at the UK National Physical Laboratory (NPL). The diodes have a natural background suppression capability through traditional pulse height and pulse rise time discrimination. The manufacturing process permits fabrication of arrays of diodes, with typical areas of ~15 mm2, thus increasing the collecting area and the signal to noise ratio, albeit with increased readout complexity. The associated multi-channel readout electronics is standard, however, and commonly used in existing X-ray sensors. Simple portable sensors based on these heterodiodes are expected to have applications in the detection of nuclear materials in a variety of security related situations.

Ablation and cone formation mechanism on CR-39 by ArF laser irradiation

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

Shakeri Jooybari, B., E-mail: baninshakery@gmail.com, E-mail: hafarideh@aut.ac.ir; Nuclear Science and Technology Research Institute NSRT, Tehran; Afarideh, H., E-mail: baninshakery@gmail.com, E-mail: hafarideh@aut.ac.ir

In this work, chemical properties, surface modification, and micro structures formation on ablated polyallyl di-glycol carbonate (CR-39) polymer by ArF laser irradiation (λ = 193 nm) at various fluences and pulse number were investigated. CR-39 samples have been irradiated with an ArF laser (193 nm) at a repetition rate of 1 Hz. Threshold fluence of ablation and effective absorption coefficient of CR-39 were determined. Conical microstructures (Taylor cone) formed on laser-ablated CR-39 exhibit: smooth, Taylor cone shape walls and sharp tips together with interference and well defined fringe-structure with a period of 230 nm, around cone base. Mechanism of cone formation and cone evolution of CR-39more » ablated surface were investigated by change of fluences (at a given pulse number) and pulse number (at a given fluence). Cone height, cone base, and region of interface were increased in micrometer steps by increasing the total fluence. Depression on the base of the cone and the circular fringe were simulated. FTIR spectra were measured and energy dispersive x-ray analysis of irradiated and un-irradiated samples was performed.« less

Effect on radioactivity concentration estimation of radon progenies with NaI(Tl) pulse height distribution from considering geometric structure around detector and infiltration of radionuclides.

PubMed

Hirouchi, J; Terasaka, Y; Hirao, S; Moriizumi, J; Yamazawa, H

2015-11-01

The surface radioactivity concentrations of the radon progenies, (214)Pb and (214)Bi, were estimated from NaI(Tl) pulse height distributions during rain. The improvement in estimation errors caused by considering geometric structures around measuring points and infiltration of radionuclides was discussed. The surface radioactivity concentrations were determined by comparing the count rates at the full-energy peak ranges between observation and calculation with the electron-photon transport code EGS5. It was shown that the concentrations can be underestimated by about 30 % unless the obstacles around the detector or infiltration of radionuclides are considered in gamma ray transfer calculations at measuring points, where there are many tall obstacles, or the ground is covered with unpaved areas. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Thermal study of bare tips with various system parameters and incision sizes.

PubMed

Osher, Robert H; Injev, Valentine P

2006-05-01

To identify major and minor surgeon-controlled parameters that affect incision temperature when performing microincision lens removal using the Alcon Infiniti Vision System. In vitro research and development laboratory, Alcon Research, Irvine, California, USA. Phacoemulsification was performed in eye-bank cadaver eyes and the following parameters evaluated: incision, duty cycle, ultrasound (US) power, aspiration flow rate (AFR), vacuum, pulse, bottle height and balanced salt solution temperature, and tip design/size. Each parameter was varied while the others remained constant. The resulting temperature of the incision and US tip was measured using a thermal camera. Major contributors to elevated incision temperature included incision size, US power, duty cycle, AFR, vacuum setting, tip design, and presence of an ophthalmic viscosurgical device (OVD). Minor contributors included pulse frequency, bottle height, and temperature of the infusate. Microincision lens removal can be performed at safe temperatures with the knowledgeable selection of surgeon-controlled parameters.

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

Dickens, Peter T.; Marcial, Jose; McCloy, John

In this study, LiAlO 2 crystals doped with rare-earth elements and Ti were produced by the CZ method and spectroscopic and neutron detection properties were investigated. Photoluminescence revealed no clear luminescent activation of LiAlO 2 by the rare-earth dopants though some interesting luminescence was observed from secondary phases within the crystal. Gamma-ray pulse height spectra collected using a 137Cs source exhibited only a Compton edge for the crystals. Neutron modeling using Monte Carlo N-Particle Transport Code revealed most neutrons used in the detection setup are thermalized, and while using natural lithium in the crystal growth, which contains 7.6% 6Li, amore » 10 mm Ø by 10 mm sample of LiAlO 2 has a 70.7% intrinsic thermal neutron capture efficiency. Furthermore, the pulse height spectra collected using a 241Am-Be neutron source demonstrated a distinct neutron peak.« less

Time and position sensitive single photon detector for scintillator read-out

NASA Astrophysics Data System (ADS)

Schössler, S.; Bromberger, B.; Brandis, M.; Schmidt, L. Ph H.; Tittelmeier, K.; Czasch, A.; Dangendorf, V.; Jagutzki, O.

2012-02-01

We have developed a photon counting detector system for combined neutron and γ radiography which can determine position, time and intensity of a secondary photon flash created by a high-energy particle or photon within a scintillator screen. The system is based on a micro-channel plate photomultiplier concept utilizing image charge coupling to a position- and time-sensitive read-out anode placed outside the vacuum tube in air, aided by a standard photomultiplier and very fast pulse-height analyzing electronics. Due to the low dead time of all system components it can cope with the high throughput demands of a proposed combined fast neutron and dual discrete energy γ radiography method (FNDDER). We show tests with different types of delay-line read-out anodes and present a novel pulse-height-to-time converter circuit with its potential to discriminate γ energies for the projected FNDDER devices for an automated cargo container inspection system (ACCIS).

Photon Counting Imaging with an Electron-Bombarded Pixel Image Sensor

PubMed Central

Hirvonen, Liisa M.; Suhling, Klaus

2016-01-01

Electron-bombarded pixel image sensors, where a single photoelectron is accelerated directly into a CCD or CMOS sensor, allow wide-field imaging at extremely low light levels as they are sensitive enough to detect single photons. This technology allows the detection of up to hundreds or thousands of photon events per frame, depending on the sensor size, and photon event centroiding can be employed to recover resolution lost in the detection process. Unlike photon events from electron-multiplying sensors, the photon events from electron-bombarded sensors have a narrow, acceleration-voltage-dependent pulse height distribution. Thus a gain voltage sweep during exposure in an electron-bombarded sensor could allow photon arrival time determination from the pulse height with sub-frame exposure time resolution. We give a brief overview of our work with electron-bombarded pixel image sensor technology and recent developments in this field for single photon counting imaging, and examples of some applications. PMID:27136556

Systems for measuring response statistics of gigahertz bandwidth photomultipliers

NASA Technical Reports Server (NTRS)

Abshire, J. B.; Rowe, H. E.

1977-01-01

New systems have been developed for measuring the average impulse response, the pulse-height spectrum, the transit-time statistics as a function of signal level, and the dark-count spectrum of gigahertz bandwidth photomultipliers. Measurements showed that the 0.53 microns pulse used as an optical test source had a 30 picoseconds and less than 70 ps pulse width. Calibration data showed the system resolution to be less than 20 ps for root mean square transit-time measurements. Test data for a static crossed-field photomultiplier showed 2-photoelectron resolution and less than 30-ps time jitter over the 1- to 100-photoelectron range.

(6)Li-loaded liquid scintillators with pulse shape discrimination.

PubMed

Greenwood, L R; Chellew, N R; Zarwell, G A

1979-04-01

Excellent pulse height and pulse shape discrimination performance has been obtained for liquid scintillators containing as much as 10 wt.% (6)Li-salicylate dissolved in a toluene-methanol solvent system using naphthalene and 9,10 diphenylanthracene as intermediate and secondary solutes. This solution has improved performance at higher (6)Li-loading than solutions in dioxane-water solvent systems, and remains stable at temperatures as low as -10 degrees C. Cells as large as 5 cm in diameter and 15.2 deep have been prepared which have a higher light output for slow neutron detection than (10)B-loaded liquids. Neutron efficiency calculations are also presented.

An integrated circuit/microsystem/nano-enhanced four species radiation sensor for inexpensive fissionable material detection

NASA Astrophysics Data System (ADS)

Waguespack, Randy Paul

2011-12-01

Small scale radiation detectors sensitive to alpha, beta, electromagnetic, neutron radiation are needed to combat the threat of nuclear terrorism and maintain national security. There are many types of radiation detectors on the market, and the type of detector chosen is usually determined by the type of particle to be detected. In the case of fissionable material, an ideal detector needs to detect all four types of radiation, which is not the focus of many detectors. For fissionable materials, the two main types of radiation that must be detected are gamma rays and neutrons. Our detector uses a glass or quartz scintillator doped with 10B nanoparticles to detect all four types of radiation particles. Boron-10 has a thermal neutron cross section of 3,840 barns. The interaction between the neutron and boron results in a secondary charge particle in the form of an alpha particle to be emitted, which is detectable by the scintillator. Radiation impinging on the scintillator matrix produces varying optical pulses dependent on the energy of the particles. The optical pulses are then detected by a photomultiplier (PM) tube, creating a current proportional to the energy of the particle. Current pulses from the PM tube are differentiated by on-chip pulse height spectroscopy, allowing for source discrimination. The pulse height circuitry has been fabricated with discrete circuits and designed into an integrated circuit package. The ability to replace traditional PM tubes with a smaller, less expensive photomultiplier will further reduce the size of the device and enhance the cost effectiveness and portability of the detector.

An explanation for parallel electric field pulses observed over thunderstorms

NASA Astrophysics Data System (ADS)

Kelley, M. C.; Barnum, B. H.

2009-10-01

Every electric field instrument flown on sounding rockets over a thunderstorm has detected pulses of electric fields parallel to the Earth's magnetic field associated with every strike. This paper describes the ionospheric signatures found during a flight from Wallops Island, Virginia, on 2 September 1995. The electric field results in a drifting Maxwellian corresponding to energies up to 1 eV. The distribution function relaxes because of elastic and inelastic collisions, resulting in electron heating up to 4000-5000 K and potentially observable red line emissions and enhanced ISR electron temperatures. The field strength scales with the current in cloud-to-ground strikes and falls off as r -1 with distance. Pulses of both polarities are found, although most electric fields are downward, parallel to the magnetic field. The pulse may be the reaction of ambient plasma to a current pulse carried at the whistler packet's highest group velocity. The charge source required to produce the electric field is very likely electrons of a few keV traveling at the packet velocity. We conjecture that the current source is the divergence of the current flowing at mesospheric heights, the phenomenon called an elve. The whistler packet's effective radiated power is as high as 25 mW at ionospheric heights, comparable to some ionospheric heater transmissions. Comparing the Poynting flux at the base of the ionosphere with flux an equal distance away along the ground, some 30 db are lost in the mesosphere. Another 10 db are lost in the transition from free space to the whistler mode.

Lightning protection using energized Franklin rods

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

Abdel-Salam, M.; Al-Abdul-Latif, U.

1995-12-31

In this paper, the onset criterion of the upward streamers from an energized Franklin rod is formulated as a function of the geometry of the rod and the height and current of the downward leader. The electric field in the vicinity of the lightning rod is calculated using the charge simulation technique. The dependency of the radius of protection on the amplitude of the pulse voltage applied to Franklin rod, the downward leader current and the tip radius and height of the rod is investigated.

Effects of Presowing Pulsed Electromagnetic Treatment of Tomato Seed on Growth, Yield, and Lycopene Content

PubMed Central

Efthimiadou, Aspasia; Katsenios, Nikolaos; Papastylianou, Panayiota; Triantafyllidis, Vassilios; Travlos, Ilias; Bilalis, Dimitrios J.

2014-01-01

The use of magnetic field as a presowing treatment has been adopted by researchers as a new environmental friendly technique. The aim of this study was to determine the effect of magnetic field exposure on tomato seeds covering a range of parameters such as transplanting percentage, plant height, shoot diameter, number of leaves per plant, fresh weight, dry weight, number of flowers, yield, and lycopene content. Pulsed electromagnetic field was used for 0, 5, 10, and 15 minutes as a presowing treatment of tomato seeds in a field experiment for two years. Papimi device (amplitude on the order of 12.5 mT) has been used. The use of pulsed electromagnetic field as a presowing treatment was found to enhance plant growth in tomato plants at certain duration of exposure. Magnetic field treatments and especially the exposure of 10 and 15 minutes gave the best results in all measurements, except plant height and lycopene content. Yield per plant was higher in magnetic field treatments, compared to control. MF-15 treatment yield was 80.93% higher than control treatment. Lycopene content was higher in magnetic field treatments, although values showed no statistically significant differences. PMID:25097875

Pulsed electric field assisted assembly of polyaniline

NASA Astrophysics Data System (ADS)

Kumar, Arun; Kazmer, David O.; Barry, Carol M. F.; Mead, Joey L.

2012-08-01

Assembling conducting polyaniline (PANi) on pre-patterned nano-structures by a high rate, commercially viable route offers an opportunity for manufacturing devices with nanoscale features. In this work we report for the first time the use of pulsed electric field to assist electrophoresis for the assembly of conducting polyaniline on gold nanowire interdigitated templates. This technique offers dynamic control over heat build-up, which has been a main drawback in the DC electrophoresis and AC dielectrophoresis as well as the main cause of nanowire template damage. The use of this technique allowed higher voltages to be applied, resulting in shorter assembly times (e.g., 17.4 s, assembly resolution of 100 nm). Moreover, the area coverage increases with the increase in number of pulses. A similar trend was observed with the deposition height and the increase in deposition height followed a linear trend with a correlation coefficient of 0.95. When the experimental mass deposited was compared with Hamaker’s theoretical model, the two were found to be very close. The pre-patterned templates with PANi deposition were subsequently used to transfer the nanoscale assembled PANi from the rigid templates to thermoplastic polyurethane using the thermoforming process.

Characterization of reticulated vitreous carbon foam using a frisch-grid parallel-plate ionization chamber

NASA Astrophysics Data System (ADS)

Edwards, Nathaniel S.; Conley, Jerrod C.; Reichenberger, Michael A.; Nelson, Kyle A.; Tiner, Christopher N.; Hinson, Niklas J.; Ugorowski, Philip B.; Fronk, Ryan G.; McGregor, Douglas S.

2018-06-01

The propagation of electrons through several linear pore densities of reticulated vitreous carbon (RVC) foam was studied using a Frisch-grid parallel-plate ionization chamber pressurized to 1 psig of P-10 proportional gas. The operating voltages of the electrodes contained within the Frisch-grid parallel-plate ionization chamber were defined by measuring counting curves using a collimated 241Am alpha-particle source with and without a Frisch grid. RVC foam samples with linear pore densities of 5, 10, 20, 30, 45, 80, and 100 pores per linear inch were separately positioned between the cathode and anode. Pulse-height spectra and count rates from a collimated 241Am alpha-particle source positioned between the cathode and each RVC foam sample were measured and compared to a measurement without an RVC foam sample. The Frisch grid was positioned in between the RVC foam sample and the anode. The measured pulse-height spectra were indiscernible from background and resulted in negligible net count rates for all RVC foam samples. The Frisch grid parallel-plate ionization chamber measurement results indicate that electrons do not traverse the bulk of RVC foam and consequently do not produce a pulse.

a Comparitive Study Using Geometric and Vertical Profile Features Derived from Airborne LIDAR for Classifying Tree Genera

NASA Astrophysics Data System (ADS)

Ko, C.; Sohn, G.; Remmel, T. K.

2012-07-01

We present a comparative study between two different approaches for tree genera classification using descriptors derived from tree geometry and those derived from the vertical profile analysis of LiDAR point data. The different methods provide two perspectives for processing LiDAR point clouds for tree genera identification. The geometric perspective analyzes individual tree crowns in relation to valuable information related to characteristics of clusters and line segments derived within crowns and overall tree shapes to highlight the spatial distribution of LiDAR points within the crown. Conversely, analyzing vertical profiles retrieves information about the point distributions with respect to height percentiles; this perspective emphasizes of the importance that point distributions at specific heights express, accommodating for the decreased point density with respect to depth of canopy penetration by LiDAR pulses. The targeted species include white birch, maple, oak, poplar, white pine and jack pine at a study site northeast of Sault Ste. Marie, Ontario, Canada.

ICESat and ICESat-2: Preparing to assess decadal-scale elevation change over the ice sheets

NASA Astrophysics Data System (ADS)

Webb, C. E.; Markus, T.; Neumann, T.; Anthony, M.

2016-12-01

One of the first, and most dramatic, assessments of elevation change to occur after the Ice, Cloud and land Elevation Satellite-2 (ICESat-2) enters its science orbit in early 2018 will be to compare the altimetry data being collected to the baseline established by the original ICESat mission between 2003 and 2009. Both missions use altimeters that send laser pulses from the satellite to the Earth. By measuring the travel time, the range to the surface can be inferred, and then combined with the position of the satellite and the pointing direction of the laser to determine where the pulse landed on the surface and its height there. The first ICESat mission employed a single-beam, full-waveform altimeter with a near-infrared (1064-nm wavelength) laser pulsed at 40 Hz. This produced surface heights at 170-meter intervals along reference tracks that extended to +/- 86 degrees latitude. ICESat-2 will carry an altimeter that sends a green (532-nm wavelength) laser through a diffractive optical element to be split into six beams, and pulsed at 10kHz. This will yield overlapping footprints every 70 cm along each beam track, extending to +/-88 degrees latitude. Rather than capturing the full returned waveform, however, the altimeter will use photon-counting detectors to measure the travel times of individual photons. Once on the ground, these data will be used in the science data processing system to produce a latitude, longitude and ellipsoidal height, marking the location from which each photon returned from the surface. Higher-level data products will characterize the surface more precisely by aggregating photons to reduce noise along each of the six beam tracks. Here, we describe the ICESat and ICESat-2 measurements and ice sheet data products, and discuss possible methods for comparing them to assess elevation change over the Greenland and Antarctic ice sheets in the nine years between the two missions.

Silicon structuring by etching with liquid chlorine and fluorine precursors using femtosecond laser pulses

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

Radu, C.; Simion, S.; Zamfirescu, M.

2011-08-01

The aim of this study is to investigate the micrometer and submicrometer scale structuring of silicon by liquid chlorine and fluorine precursors with 200 fs laser pulses working at both fundamental (775 nm) and frequency doubled (387 nm) wavelengths. The silicon surface was irradiated at normal incidence by immersing the Si (111) substrates in a glass container filled with liquid chlorine (CCl{sub 4}) and fluorine (C{sub 2}Cl{sub 3}F{sub 3}) precursors. We report that silicon surfaces develop an array of spikes with single step irradiation processes at 775 nm and equally at 387 nm. When irradiating the Si surface with 400more » pulses at 330 mJ/cm{sup 2} laser fluence and a 775 nm wavelength, the average height of the formed Si spikes in the case of fluorine precursors is 4.2 {mu}m, with a full width at half maximum of 890 nm. At the same irradiation wavelength chlorine precursors develop Si spikes 4 {mu}m in height and with a full width at half maximum of 2.3 {mu}m with irradiation of 700 pulses at 560 mJ/cm{sup 2} laser fluence. Well ordered areas of submicrometer spikes with an average height of about 500 nm and a width of 300 nm have been created by irradiation at 387 nm by chlorine precursors, whereas the fluorine precursors fabricate spikes with an average height of 700 nm and a width of about 200 nm. Atomic force microscopy and scanning electron microscopy of the surface show that the formation of the micrometer and sub-micrometer spikes involves a combination of capillary waves on the molten silicon surface and laser-induced etching of silicon, at both 775 nm and 387 nm wavelength irradiation. The energy-dispersive x-ray measurements indicate the presence of chlorine and fluorine precursors on the structured surface. The fluorine precursors create a more ordered area of Si spikes at both micrometer and sub-micrometer scales. The potential use of patterned Si substrates with gradient topography as model scaffolds for the systematic exploration of the role of 3D micro/nano morphology on cell adhesion and growth is envisaged.« less

Combination neutron-gamma ray detector

DOEpatents

Stuart, Travis P.; Tipton, Wilbur J.

1976-10-26

A radiation detection system capable of detecting neutron and gamma events and distinguishing therebetween. The system includes a detector for a photomultiplier which utilizes a combination of two phosphor materials, the first of which is in the form of small glass beads which scintillate primarily in response to neutrons and the second of which is a plastic matrix which scintillates in response to gammas. A combination of pulse shape and pulse height discrimination techniques is utilized to provide an essentially complete separation of the neutron and gamma events.

Numerical simulation of the early-time high altitude electromagnetic pulse

NASA Astrophysics Data System (ADS)

Meng, Cui; Chen, Yu-Sheng; Liu, Shun-Kun; Xie, Qin-Chuan; Chen, Xiang-Yue; Gong, Jian-Cheng

2003-12-01

In this paper, the finite difference method is used to develop the Fortran software MCHII. The physical process in which the electromagnetic signal is generated by the interaction of nuclear-explosion-induced Compton currents with the geomagnetic field is numerically simulated. The electromagnetic pulse waveforms below the burst point are investigated. The effects of the height of burst, yield and the time-dependence of gamma-rays are calculated by using the MCHII code. The results agree well with those obtained by using the code CHAP.

Rigor of cell fate decision by variable p53 pulses and roles of cooperative gene expression by p53

PubMed Central

Murakami, Yohei; Takada, Shoji

2012-01-01

Upon DNA damage, the cell fate decision between survival and apoptosis is largely regulated by p53-related networks. Recent experiments found a series of discrete p53 pulses in individual cells, which led to the hypothesis that the cell fate decision upon DNA damage is controlled by counting the number of p53 pulses. Under this hypothesis, Sun et al. (2009) modeled the Bax activation switch in the apoptosis signal transduction pathway that can rigorously “count” the number of uniform p53 pulses. Based on experimental evidence, here we use variable p53 pulses with Sun et al.’s model to investigate how the variability in p53 pulses affects the rigor of the cell fate decision by the pulse number. Our calculations showed that the experimentally anticipated variability in the pulse sizes reduces the rigor of the cell fate decision. In addition, we tested the roles of the cooperativity in PUMA expression by p53, finding that lower cooperativity is plausible for more rigorous cell fate decision. This is because the variability in the p53 pulse height is more amplified in PUMA expressions with more cooperative cases. PMID:27857606

Wireless Monitoring of the Height of Condensed Water in Steam Pipes

NASA Technical Reports Server (NTRS)

Lee, Hyeong Jae; Bar-Cohen, Yoseph; Lih, Shyh-Shiuh; Badescu, Mircea; Dingizian, Arsham; Takano, Nobuyuki; Blosiu, Julian O.

2014-01-01

A wireless health monitoring system has been developed for determining the height of water condensation in the steam pipes and the data acquisition is done remotely using a wireless network system. The developed system is designed to operate in the harsh environment encountered at manholes and the pipe high temperature of over 200 °C. The test method is an ultrasonic pulse-echo and the hardware includes a pulser, receiver and wireless modem for communication. Data acquisition and signal processing software were developed to determine the water height using adaptive signal processing and data communication that can be controlled while the hardware is installed in a manhole. A statistical decision-making tool is being developed based on the field test data to determine the height of in the condensed water under high noise conditions and other environmental factors.

Positron Scanner for Locating Brain Tumors

DOE R&D Accomplishments Database

Rankowitz, S.; Robertson, J. S.; Higinbotham, W. A.; Rosenblum, M. J.

1962-03-01

A system is described that makes use of positron emitting isotopes for locating brain tumors. This system inherently provides more information about the distribution of radioactivity in the head in less time than existing scanners which use one or two detectors. A stationary circular array of 32 scintillation detectors scans a horizontal layer of the head from many directions simultaneously. The data, consisting of the number of counts in all possible coincidence pairs, are coded and stored in the memory of a Two-Dimensional Pulse-Height Analyzer. A unique method of displaying and interpreting the data is described that enables rapid approximate analysis of complex source distribution patterns. (auth)

Solid-state repetitive generator with a gyromagnetic nonlinear transmission line operating as a peak power amplifier

NASA Astrophysics Data System (ADS)

Gusev, A. I.; Pedos, M. S.; Rukin, S. N.; Timoshenkov, S. P.

2017-07-01

In this work, experiments were made in which gyromagnetic nonlinear transmission line (NLTL) operates as a peak power amplifier of the input pulse. At such an operating regime, the duration of the input pulse is close to the period of generated oscillations, and the main part of the input pulse energy is transmitted only to the first peak of the oscillations. Power amplification is achieved due to the voltage amplitude of the first peak across the NLTL output exceeding the voltage amplitude of the input pulse. In the experiments, the input pulse with an amplitude of 500 kV and a half-height pulse duration of 7 ns is applied to the NLTL with a natural oscillation frequency of ˜300 MHz. At the output of the NLTL in 40 Ω coaxial transmission line, the pulse amplitude is increased to 740 kV and the pulse duration is reduced to ˜2 ns, which correspond to power amplification of the input pulse from ˜6 to ˜13 GW. As a source of input pulses, a solid-state semiconductor opening switch generator was used, which allowed carrying out experiments at pulse repetition frequency up to 1 kHz in the burst mode of operation.

Miniature High-Let Radiation Spectrometer for Space and Avionics Applications

NASA Technical Reports Server (NTRS)

Stassinopoulos, E. G.; Stauffer, Craig A.; Brucker, G. J.

1998-01-01

This paper reports on the design and characterization of a small, low power, and low weight instrument, a High-LET Radiation Spectrometer (HiLRS), that measures energy deposited by heavy ions in microelectronic devices. The HILRS operates on pulse-height analysis principles and is designed for space and avionics applications. The detector component in the instrument is based on large scale arrays of p-n junctions. In this system, the pulse amplitude from a particle hit is directly proportional to the particle LET. A prototype flight unit has been fabricated and calibrated using several heavy ions with varying LETs and protons with several energies. The unit has been delivered to the Ballistic Missile Defense Organization (BMDO) c/o the Air Force Research Laboratory in Albuquerque, NM, for integration into the military Space Technology Research Vehicle (STRV), a US-UK cooperative mission. Another version of HILRS is being prepared for delivery in April to the Hubble Space Telescope (HST) project, to fly on the HST Orbital Systems Test (HOST) Platform on a shuttle mission.

Single photon detection and timing in the Lunar Laser Ranging Experiment.

NASA Technical Reports Server (NTRS)

Poultney, S. K.

1972-01-01

The goals of the Lunar Laser Ranging Experiment lead to the need for the measurement of a 2.5 sec time interval to an accuracy of a nanosecond or better. The systems analysis which included practical retroreflector arrays, available laser systems, and large telescopes led to the necessity of single photon detection. Operation under all background illumination conditions required auxiliary range gates and extremely narrow spectral and spatial filters in addition to the effective gate provided by the time resolution. Nanosecond timing precision at relatively high detection efficiency was obtained using the RCA C31000F photomultiplier and Ortec 270 constant fraction of pulse-height timing discriminator. The timing accuracy over the 2.5 sec interval was obtained using a digital interval with analog vernier ends. Both precision and accuracy are currently checked internally using a triggerable, nanosecond light pulser. Future measurements using sub-nanosecond laser pulses will be limited by the time resolution of single photon detectors.

Junction-to-Case Thermal Resistance of a Silicon Carbide Bipolar Junction Transistor Measured

NASA Technical Reports Server (NTRS)

Niedra, Janis M.

2006-01-01

Junction temperature of a prototype SiC-based bipolar junction transistor (BJT) was estimated by using the base-emitter voltage (V(sub BE)) characteristic for thermometry. The V(sub BE) was measured as a function of the base current (I(sub B)) at selected temperatures (T), all at a fixed collector current (I(sub C)) and under very low duty cycle pulse conditions. Under such conditions, the average temperature of the chip was taken to be the same as that of the temperature-controlled case. At increased duty cycle such as to substantially heat the chip, but same I(sub C) pulse height, the chip temperature was identified by matching the V(sub BE) to the thermometry curves. From the measured average power, the chip-to-case thermal resistance could be estimated, giving a reasonable value. A tentative explanation for an observed bunching with increasing temperature of the calibration curves may relate to an increasing dopant atom ionization. A first-cut analysis, however, does not support this.

Apparatus and system for multivariate spectral analysis

DOEpatents

Keenan, Michael R.; Kotula, Paul G.

2003-06-24

An apparatus and system for determining the properties of a sample from measured spectral data collected from the sample by performing a method of multivariate spectral analysis. The method can include: generating a two-dimensional matrix A containing measured spectral data; providing a weighted spectral data matrix D by performing a weighting operation on matrix A; factoring D into the product of two matrices, C and S.sup.T, by performing a constrained alternating least-squares analysis of D=CS.sup.T, where C is a concentration intensity matrix and S is a spectral shapes matrix; unweighting C and S by applying the inverse of the weighting used previously; and determining the properties of the sample by inspecting C and S. This method can be used by a spectrum analyzer to process X-ray spectral data generated by a spectral analysis system that can include a Scanning Electron Microscope (SEM) with an Energy Dispersive Detector and Pulse Height Analyzer.

Technical guidance and analytic services in support of SEASAT-A. [radar altimeters for altimetry and ocean wave height

NASA Technical Reports Server (NTRS)

Brooks, W. L.; Dooley, R. P.

1975-01-01

The design of a high resolution radar for altimetry and ocean wave height estimation was studied. From basic principles, it is shown that a short pulse wide beam radar is the most appropriate and recommended technique for measuring both altitude and ocean wave height. To achieve a topographic resolution of + or - 10 cm RMS at 5.0 meter RMS wave heights, as required for SEASAT-A, it is recommended that the altimeter design include an onboard adaptive processor. The resulting design, which assumes a maximum likelihood estimation (MLE) processor, is shown to satisfy all performance requirements. A design summary is given for the recommended radar altimeter, which includes a full deramp STRETCH pulse compression technique followed by an analog filter bank to separate range returns as well as the assumed MLE processor. The feedback loop implementation of the MLE on a digital computer was examined in detail, and computer size, estimation accuracies, and bias due to range sidelobes are given for the MLE with typical SEASAT-A parameters. The standard deviation of the altitude estimate was developed and evaluated for several adaptive and nonadaptive split-gate trackers. Split-gate tracker biases due to range sidelobes and transmitter noise are examined. An approximate closed form solution for the altimeter power return is derived and evaluated. The feasibility of utilizing the basic radar altimeter design for the measurement of ocean wave spectra was examined.

Radial diffusion, vertical transport, and refixation of labeled bicarbonate in scots pine stems

NASA Astrophysics Data System (ADS)

Marshall, J. D.; Tarvainen, L.; Wallin, G.

2016-12-01

The CO2 produced by a respiring stem provides an index of metabolic activity in the stem and a quantitative estimate of an important component of the forest carbon budget. Production of CO2 by a given stem volume is lost by three competing processes. First, some diffuses radially outward through the bark. Second, some is dissolved and vertically transported upward out of the control volume by the xylem stream. Third, some is refixed by photosynthesis under the bark. The relative balance among these pathways was quantified in 17-m Scots pine trees by 13C-bicarbonate labeling of the xylem stream and monitoring of the 13CO2 in the xylem water, along with continuous monitoring of the radial diffusive flux at four canopy heights and in transpiration from leaves. Most of the label diffused out radially, as 13CO2, immediately above the labeling site, over about a week. The pulse was weakly and briefly detected 4 m above that height. Further up the stem it was not detected at all. We detected significant refixation of CO2 in the stems at all heights above 4 m, where the bark becomes papery and thin, but the label was so weak at this height that refixation had little influence on the pulse chase. We conclude that the vertical flux is negligible in Scots pine, but that the refixation flux must be accounted for in estimates of whole-stem CO2 efflux.

Calibration of an electronic counter and pulse height analyzer for plotting erythrocyte volume spectra.

DOT National Transportation Integrated Search

1963-03-01

A simple technique is presented for calibrating an electronic system used in the plotting of erythrocyte volume spectra. The calibration factors, once obtained, apparently remain applicable for some time. Precise estimates of calibration factors appe...

Changes in Central Aortic Pressure Levels, Wave Components and Determinants Associated with High Peripheral Blood Pressure States in Childhood: Analysis of Hypertensive Phenotype.

PubMed

García-Espinosa, Victoria; Curcio, Santiago; Marotta, Marco; Castro, Juan M; Arana, Maite; Peluso, Gonzalo; Chiesa, Pedro; Giachetto, Gustavo; Bia, Daniel; Zócalo, Yanina

2016-10-01

The aims were to determine whether children's high peripheral blood pressure states (HBP) are associated with increased central aortic blood pressure (BP) and to characterize hemodynamic and vascular changes associated with HBP in terms of changes in cardiac output (stroke volume, SV), arterial stiffness (aortic pulse wave velocity, PWV), peripheral vascular resistances (PVR) and net and relative contributions of reflected waves to the aortic pulse amplitude. We included 154 subjects (mean age 11; range 4-16 years) assigned to one of two groups: normal peripheral BP (NBP, n = 101), defined as systolic and diastolic BP < 90th percentile, or high BP (HBP, n = 53), defined as average systolic and/or diastolic BP levels ≥90th percentile (curves for sex, age and body height). The HBP group included children with hypertensive and pre-hypertensive BP levels. After a first analysis, groups were compared excluding obese and dyslipidemic children. Peripheral and central aortic BP, PWV and pulse wave-derived parameters (augmentation index, forward and backward wave components' amplitude) were measured using gold-standard techniques, applanation tonometry (SphygmoCor) and oscillometry (Mobil-O-Graph). Independent of the presence of dyslipidemia and/or obesity, aortic systolic and pulse BP were higher in HBP than in NBP children. The increase in central BP could not be explained by an increase in the relative contribution of reflections to the aortic pressure wave, higher PVR or by an augmented peripheral reflection coefficient. Instead, the rise in central BP would be explained by an increase in the amplitude of both incident and reflected wave components.

Investigation of endothelial function by pulse contour analysis: a protocol for drug administration and timing of pulse contour assessment

PubMed Central

Gordon, Sarah E; Cartwright, Neil; Griffiths, Mark J D

2009-01-01

AIMS Pulse contour analysis (PCA) obtained by finger photoplethysmography produces a digital volume pulse (DVP) including an inflection point in its down-slope. The reflection index (RI: ratio of the inflection point height over the maximal DVP) is responsive to vasodilatation. We aimed to optimize the drug dose and time interval for assessing endothelial function using PCA in healthy volunteers and patients with severe coronary artery disease. METHODS Time and dose to RI response relationships were constructed in 16 volunteers and nine patients to inhaled salbutamol (100–400 µg) or sublingual nitroglycerin (NTG; 25–400 µg). RESULTS For the volunteers, the time to maximum RI response to inhaled salbutamol and sublingual NTG was 10.73 ± 0.41 and 3.66 ± 0.21 min, respectively. A plateau in the RI response to salbutamol occurred between 5 and 15 min after inhalation and results were averaged over this period. A dose-dependent response was observed to inhaled salbutamol and sublingual NTG (P= 0.05 and P < 0.001 by repeated-measures anova, respectively) in healthy volunteers. By contrast, in patients with severe coronary artery disease inhaled salbutamol (100–400 µg) did not cause a significant change in RI. CONCLUSIONS In healthy volunteers the RI response to inhaled salbutamol (100–200 µg) averaged over 5–15 min after administration may be used to investigate endothelial function by PCA. The response to sublingual NTG (50 µg) should be determined at 4 min. This technique may not be suitable for the assessment of endothelial function in subjects with extensive coronary artery disease owing to the small responses observed and potential confounding effect of vasoactive medication. PMID:19843066

Solitary waves in morphogenesis: Determination fronts as strain-cued strain transformations among automatous cells

NASA Astrophysics Data System (ADS)

Cox, Brian N.; Landis, Chad M.

2018-02-01

We present a simple theory of a strain pulse propagating as a solitary wave through a continuous two-dimensional population of cells. A critical strain is assumed to trigger a strain transformation, while, simultaneously, cells move as automata to tend to restore a preferred cell density. We consider systems in which the strain transformation is a shape change, a burst of proliferation, or the commencement of growth (which changes the shape of the population sheet), and demonstrate isomorphism among these cases. Numerical and analytical solutions describe a strain pulse whose height does not depend on how the strain disturbance was first launched, or the rate at which the strain transformation is achieved, or the rate constant in the rule for the restorative cell motion. The strain pulse is therefore very stable, surviving the imposition of strong perturbations: it would serve well as a timing signal in development. The automatous wave formulation is simple, with few model parameters. A strong case exists for the presence of a strain pulse during amelogenesis. Quantitative analysis reveals a simple relationship between the velocity of the leading edge of the pulse in amelogenesis and the known speed of migration of ameloblast cells. This result and energy arguments support the depiction of wave motion as an automatous cell response to strain, rather than as a response to an elastic energy gradient. The theory may also contribute to understanding the determination front in somitogenesis, moving fronts of convergent-extension transformation, and mitotic wavefronts in the syncytial drosophila embryo.

Giant sparks at cosmological distances?

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

Kulkarni, S. R.; Ofek, E. O.; Neill, J. D.

2014-12-10

Millisecond-duration bright radio pulses at 1.4 GHz with high dispersion measures (DMs) were reported by Lorimer et al., Keane et al., and Thornton et al. Their all-sky rate is ≈10{sup 4} day{sup –1} above ∼1 Jy. Related events are 'Perytons'–similar pulsed, dispersed sources, but most certainly local. Suggested models of fast radio bursts (FRBs) can originate in Earth's atmosphere, in stellar coronae, in other galaxies, and even at cosmological distances. Using physically motivated assumptions combined with observed properties, we explore these models. In our analysis, we focus on the Lorimer event: a 30 Jy, 5 ms duration burst with DMmore » = 375 cm{sup –3} pc, exhibiting a steep frequency-dependent pulse width (the Sparker). To be complete, we drop the assumption that high DMs are produced by plasma propagation and assume that the source produces pulses with frequency-dependent arrival time ('chirped signals'). Within this framework, we explore a scenario in which Perytons, the Sparker, and the FRBs are all atmospheric phenomena occurring at different heights. This model is ad hoc in that we cannot explain why Perytons at higher altitudes show greater DMs or exhibit narrower pulses. Nonetheless, we argue that the Sparker may be a Peryton. We end with two remarks. First, the detection of a single FRB by an interferometer with a kilometer (or longer) baseline will prove that FRBs are of extraterrestrial origin. Second, we urge astronomers to pursue observations and understanding of Perytons since they form (at least) a formidable foreground for the FRBs.« less

A fast-neutron detection detector based on fission material and large sensitive 4H silicon carbide Schottky diode detector

NASA Astrophysics Data System (ADS)

Liu, Linyue; Liu, Jinliang; Zhang, Jianfu; Chen, Liang; Zhang, Xianpeng; Zhang, Zhongbing; Ruan, Jinlu; Jin, Peng; Bai, Song; Ouyang, Xiaoping

2017-12-01

Silicon carbide radiation detectors are attractive in the measurement of the total numbers of pulsed fast neutrons emitted from nuclear fusion and fission devices because of high neutron-gamma discrimination and good radiation resistance. A fast-neutron detection system was developed based on a large-area 4H-SiC Schottky diode detector and a 235U fission target. Excellent pulse-height spectra of fission fragments induced by mono-energy deuterium-tritium (D-T) fusion neutrons and continuous energy fission neutrons were obtained. The detector is proven to be a good candidate for pulsed fast neutron detection in a complex radiation field.

Recycling of laser and plasma radiation energy for enhancement of extreme ultraviolet sources for nanolithography

NASA Astrophysics Data System (ADS)

Sizyuk, V.; Sizyuk, T.; Hassanein, A.; Johnson, K.

2018-01-01

We have developed comprehensive integrated models for detailed simulation of laser-produced plasma (LPP) and laser/target interaction, with potential recycling of the escaping laser and out-of-band plasma radiation. Recycling, i.e., returning the escaping laser and plasma radiation to the extreme ultraviolet (EUV) generation region using retroreflective mirrors, has the potential of increasing the EUV conversion efficiency (CE) by up to 60% according to our simulations. This would result in significantly reduced power consumption and/or increased EUV output. Based on our recently developed models, our High Energy Interaction with General Heterogeneous Target Systems (HEIGHTS) computer simulation package was upgraded for LPP devices to include various radiation recycling regimes and to estimate the potential CE enhancement. The upgraded HEIGHTS was used to study recycling of both laser and plasma-generated radiation and to predict possible gains in conversion efficiency compared to no-recycling LPP devices when using droplets of tin target. We considered three versions of the LPP system including a single CO2 laser, a single Nd:YAG laser, and a dual-pulse device combining both laser systems. The gains in generating EUV energy were predicted and compared for these systems. Overall, laser and radiation energy recycling showed the potential for significant enhancement in source efficiency of up to 60% for the dual-pulse system. Significantly higher CE gains might be possible with optimization of the pre-pulse and main pulse parameters and source size.

Simulation and analysis of atmospheric transmission performance in airborne Terahertz communication

NASA Astrophysics Data System (ADS)

Pan, Chengsheng; Shi, Xin; Liu, Chengyang; Wang, Xue; Ding, Yuanming

2018-02-01

For the special meteorological condition of high altitude transmission; first the influence of atmospheric turbulence on the Terahertz wireless communication is analyzed, and the atmospheric constants model with increase in height is given. On this basis, the relationship between the flicker index and the high altitude horizon transmission distance of the Terahertz wave is analyzed by simulation. Then, through the analysis of high altitude path loss and noise, the high altitude wireless link model is built. Finally, the link loss budget is given according to the current Terahertz device parameters, and bit error rate (BER) performance of on-off keyed modulation (OOK) and pulse position modulation (PPM) in four Terahertz frequency bands is compared and analyzed. All these above provided theoretical reference for high-altitude Terahertz wireless communication transmission.

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

Fu, Wenkai; Ghosh, Priyarshini; Harrison, Mark

The performance of traditional Hornyak buttons and two proposed variants for fast-neutron hodoscope applications was evaluated using Geant4. The Hornyak button is a ZnS(Ag)-based device previously deployed at the Idaho National Laboratory's TRansient REActor Test Facility (better known as TREAT) for monitoring fast neutrons emitted during pulsing of fissile fuel samples. Past use of these devices relied on pulse-shape discrimination to reduce the significant levels of background Cherenkov radiation. Proposed are two simple designs that reduce the overall light guide mass (here, polymethyl methacrylate or PMMA), employ silicon photomultipliers (SiPMs), and can be operated using pulse-height discrimination alone to eliminatemore » background noise to acceptable levels. Geant4 was first used to model a traditional Hornyak button, and for assumed, hodoscope-like conditions, an intrinsic efficiency of 0.35% for mono-directional fission neutrons was predicted. The predicted efficiency is in reasonably good agreement with experimental data from the literature and, hence, served to validate the physics models and approximations employed. Geant4 models were then developed to optimize the materials and geometries of two alternatives to the Hornyak button, one based on a homogeneous mixture of ZnS(Ag) and PMMA, and one based on alternating layers of ZnS(Ag) and PMMA oriented perpendicular to the incident neutron beam. For the same radiation environment, optimized, 5-cm long (along the beam path) devices of the homogeneous and layered designs were predicted to have efficiencies of approximately 1.3% and 3.3%, respectively. For longer devices, i.e., lengths larger than 25 cm, these efficiencies were shown to peak at approximately 2.2% and 5.9%, respectively. Furthermore, both designs were shown to discriminate Cherenkov noise intrinsically by using an appropriate pulse-height discriminator level, i.e., pulse-shape discrimination is not needed for these devices.« less

Gamma-ray spectra and doses from the Little Boy replica

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

Moss, C.E.; Lucas, M.C.; Tisinger, E.W.

1984-01-01

Most radiation safety guidelines in the nuclear industry are based on the data concerning the survivors of the nuclear explosions at Hiroshima and Nagasaki. Crucial to determining these guidelines is the radiation from the explosions. We have measured gamma-ray pulse-height distributions from an accurate replica of the Little Boy device used at Hiroshima, operated at low power levels near critical. The device was placed outdoors on a stand 4 m from the ground to minimize environmental effects. The power levels were based on a monitor detector calibrated very carefully in independent experiments. High-resolution pulse-height distributions were acquired with a germaniummore » detector to identify the lines and to obtain line intensities. The 7631 to 7645 keV doublet from neutron capture in the heavy steel case was dominant. Low-resolution pulse-height distributions were acquired with bismuth-germanate detectors. We calculated flux spectra from these distributions using accurately measured detector response functions and efficiency curves. We then calculated dose-rate spectra from the flux spectra using a flux-to-dose-rate conversion procedure. The integral of each dose-rate spectrum gave an integral dose rate. The integral doses at 2 m ranged from 0.46 to 1.03 mrem per 10/sup 13/ fissions. The output of the Little Boy replica can be calculated with Monte Carlo codes. Comparison of our experimental spectra, line intensities, and integral doses can be used to verify these calculations at low power levels and give increased confidence to the calculated values from the explosion at Hiroshima. These calculations then can be used to establish better radiation safety guidelines. 7 references, 7 figures, 2 tables.« less

Acute effects of ultrafiltration on aortic mechanical properties determined by measurement of pulse wave velocity and pulse propagation time in hemodialysis patients

PubMed Central

Yıldız, Banu Şahin; Şahin, Alparslan; Aladağ, Nazire Başkurt; Arslan, Gülgün; Kaptanoğulları, Hakan; Akın, İbrahim; Yıldız, Mustafa

2015-01-01

Objective: The effects of acute hemodialysis session on pulse wave velocity are conflicting. The aim of the current study was to assess the acute effects of ultrafiltration on the aortic mechanical properties using carotid-femoral (aortic) pulse wave velocity and pulse propagation time. Methods: A total of 26 (12 women, 14 men) consecutive patients on maintenance hemodialysis (mean dialysis duration: 40.7±25.6 (4-70) months) and 29 healthy subjects (13 women, 16 men) were included in this study. Baseline blood pressure, carotid-femoral (aortic) pulse wave velocity, and pulse propagation time were measured using a Complior Colson device (Createch Industrie, France) before and immediately after the end of the dialysis session. Results: While systolic blood pressure, diastolic blood pressure, mean blood pressure, pulse pressure, and pulse wave velocity were significantly higher in patients on hemodialysis than in healthy subjects, pulse propagation time was significantly higher in healthy subjects. Although body weight, systolic blood pressure, diastolic blood pressure, mean blood pressure, pulse pressure, and pulse wave velocity were significantly decreased, heart rate and pulse propagation time were significantly increased after ultrafiltration. There was a significant positive correlation between pulse wave velocity and age, body height, waist circumference, systolic blood pressure, diastolic blood pressure, mean blood pressure, pulse pressure, and heart rate. Conclusion: Although hemodialysis treatment may chronically worsen aortic mechanical properties, ultrafiltration during hemodialysis may significantly improve aortic pulse wave velocity, which is inversely related to aortic distensibility and pulse propagation time. PMID:25413228

Design and spectrum calculation of 4H-SiC thermal neutron detectors using FLUKA and TCAD

NASA Astrophysics Data System (ADS)

Huang, Haili; Tang, Xiaoyan; Guo, Hui; Zhang, Yimen; Zhang, Yimeng; Zhang, Yuming

2016-10-01

SiC is a promising material for neutron detection in a harsh environment due to its wide band gap, high displacement threshold energy and high thermal conductivity. To increase the detection efficiency of SiC, a converter such as 6LiF or 10B is introduced. In this paper, pulse-height spectra of a PIN diode with a 6LiF conversion layer exposed to thermal neutrons (0.026 eV) are calculated using TCAD and Monte Carlo simulations. First, the conversion efficiency of a thermal neutron with respect to the thickness of 6LiF was calculated by using a FLUKA code, and a maximal efficiency of approximately 5% was achieved. Next, the energy distributions of both 3H and α induced by the 6LiF reaction according to different ranges of emission angle are analyzed. Subsequently, transient pulses generated by the bombardment of single 3H or α-particles are calculated. Finally, pulse height spectra are obtained with a detector efficiency of 4.53%. Comparisons of the simulated result with the experimental data are also presented, and the calculated spectrum shows an acceptable similarity to the experimental data. This work would be useful for radiation-sensing applications, especially for SiC detector design.

A Deuterated Neutron Detector Array For Nuclear (Astro)Physics Studies

NASA Astrophysics Data System (ADS)

Almaraz-Calderon, Sergio; Asher, B. W.; Barber, P.; Hanselman, K.; Perello, J. F.

2016-09-01

The properties of neutron-rich nuclei are at the forefront of research in nuclear structure, nuclear reactions and nuclear astrophysics. The advent of intense rare isotope beams (RIBs) has opened a new door for studies of systems with very short half-lives and possible fascinating properties. Neutron spectroscopic techniques become increasingly relevant when these neutron rich nuclei are used in a variety of experiments. At Florida State University, we are developing a neutron detector array that will allow us to perform high-resolution neutron spectroscopic studies with stable and radioactive beams. The neutron detection system consists of 16 deuterated organic liquid scintillation detectors with fast response and pulse-shape discrimination capabilities. In addition to these properties, there is the potential to use the structure in the pulse-height spectra to extract the energy of the neutrons and thus produce directly excitation spectra. This type of detector uses deuterated benzene (C6D6) as the liquid scintillation medium. The asymmetric nature of the scattering between a neutron and a deuterium in the center of mass produces a pulse-height spectrum from the deuterated scintillator which contains useful information on the initial energy of the neutron. Work supported in part by the State of Florida and NSF Grant No. 1401574.

Physical exercise, fitness and dietary pattern and their relationship with circadian blood pressure pattern, augmentation index and endothelial dysfunction biological markers: EVIDENT study protocol

PubMed Central

2010-01-01

Background Healthy lifestyles may help to delay arterial aging. The purpose of this study is to analyze the relationship of physical activity and dietary pattern to the circadian pattern of blood pressure, central and peripheral blood pressure, pulse wave velocity, carotid intima-media thickness and biological markers of endothelial dysfunction in active and sedentary individuals without arteriosclerotic disease. Methods/Design Design: A cross-sectional multicenter study with six research groups. Subjects: From subjects of the PEPAF project cohort, in which 1,163 who were sedentary became active, 1,942 were sedentary and 2,346 were active. By stratified random sampling, 1,500 subjects will be included, 250 in each group. Primary measurements: We will evaluate height, weight, abdominal circumference, clinical and ambulatory blood pressure with the Radial Pulse Wave Acquisition Device (BPro), central blood pressure and augmentation index with Pulse Wave Application Software (A-Pulse) and SphymgoCor System Px (Pulse Wave Analysis), pulse wave velocity (PWV) with SphymgoCor System Px (Pulse Wave Velocity), nutritional pattern with a food intake frequency questionnaire, physical activity with the 7-day PAR questionnaire and accelerometer (Actigraph GT3X), physical fitness with the cycle ergometer (PWC-170), carotid intima-media thickness by ultrasound (Micromax), and endothelial dysfunction biological markers (endoglin and osteoprotegerin). Discussion Determining that sustained physical activity and the change from sedentary to active as well as a healthy diet improve circadian pattern, arterial elasticity and carotid intima-media thickness may help to propose lifestyle intervention programs. These interventions could improve the cardiovascular risk profile in some parameters not routinely assessed with traditional risk scales. From the results of this study, interventional approaches could be obtained to delay vascular aging that combine physical exercise and diet. Trial Registration Clinical Trials.gov Identifier: NCT01083082 PMID:20459634

Battery driven 8 channel pulse height analyzer with compact, single gamma-peak display

DOEpatents

Morgan, John P.; Piper, Thomas C.

1991-01-01

The invention comprises a hand-held wand including an l.e.d. display and a aI photomultiplier tube encased in lead or other suitable gamma shielding material, and an electronics and battery back-pack package connected to the wand.

A suspended boron foil multi-wire proportional counter neutron detector

NASA Astrophysics Data System (ADS)

Nelson, Kyle A.; Edwards, Nathaniel S.; Hinson, Niklas J.; Wayant, Clayton D.; McGregor, Douglas S.

2014-12-01

Three natural boron foils, approximately 1.0 cm in diameter and 1.0 μm thick, were obtained from The Lebow Company and suspended in a multi-wire proportional counter. Suspending the B foils allowed the alpha particle and Li ion reaction products to escape simultaneously, one on each side of the foil, and be measured concurrently in the gas volume. The thermal neutron response pulse-height spectrum was obtained and two obvious peaks appear from the 94% and 6% branches of the 10B(n,α)7Li neutron reaction. Scanning electron microscope images were collected to obtain the exact B foil thicknesses and MCNP6 simulations were completed for those same B thicknesses. Pulse-height spectra obtained from the simulations were compared to experimental data and matched well. The theoretical intrinsic thermal-neutron detection efficiency for enriched 10B foils was calculated and is presented. Additionally, the intrinsic thermal neutron detection efficiency of the three natural B foils was calculated to be 3.2±0.2%.

Spectroscopic and neutron detection properties of rare earth and titanium doped LiAlO 2 single crystals

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

Dickens, Peter T.; Marcial, José; McCloy, John

In this study, LiAlO2 crystals doped with rare-earth elements and Ti were produced by the CZ method and spectroscopic and neutron detection properties were investigated. Photoluminescence revealed no clear luminescent activation of LiAlO2 by the rare-earth dopants though some interesting luminescence was observed from secondary phases within the crystal. Gamma-ray pulse height spectra collected using a 137Cs source exhibited only a Compton edge for the crystals. Neutron modeling using Monte Carlo N-Particle Transport Code revealed most neutrons used in the detection setup are thermalized, and while using natural lithium in the crystal growth, which contains 7.6 % 6Li, a 10more » mm Ø by 10 mm sample of LiAlO2 has a 70.7 % intrinsic thermal neutron capture efficiency. Furthermore, the pulse height spectra collected using a 241Am-Be neutron source demonstrated a distinct neutron peak.« less

Optimization of the performance of a tandem microchannel plate detector as a function of interplate spacing and voltage

NASA Technical Reports Server (NTRS)

Rogers, D.; Malina, R. F.

1982-01-01

The effect of varying the size of the gap voltage and spacing on the performance of a tandem pair of microchannel plates (MCP) is investigated. Results show that increasing the voltage in the gap increases the gain of the pair and also produces a narrower Gaussian pulse-height distribution, although beyond a critical voltage the gain of the channel plate pair is found to plateau. A model is developed which explains the nonlinear gain behavior of individual microchannels and the behavior of the electron cloud emitted from the first MCP as it spreads out between the two MCPs and hits the surface of the second. The model calculates the plateau voltage as a function of the gap size, the gain of each MCP, and the diameter of the channels, and is found to show good agreement with the observed results. It is concluded that interplate gaps of up to several millimeters can be accommodated without a significant degradation in pulse-height distribution.

Calibration of high-dynamic-range, finite-resolution x-ray pulse-height spectrometers for extracting electron energy distribution data from the PFRC-2 device

NASA Astrophysics Data System (ADS)

Swanson, C.; Jandovitz, P.; Cohen, S. A.

2017-10-01

Knowledge of the full x-ray energy distribution function (XEDF) emitted from a plasma over a large dynamic range of energies can yield valuable insights about the electron energy distribution function (EEDF) of that plasma and the dynamic processes that create them. X-ray pulse height detectors such as Amptek's X-123 Fast SDD with Silicon Nitride window can detect x-rays in the range of 200eV to 100s of keV. However, extracting EEDF from this measurement requires precise knowledge of the detector's response function. This response function, including the energy scale calibration, the window transmission function, and the resolution function, can be measured directly. We describe measurements of this function from x-rays from a mono-energetic electron beam in a purpose-built gas-target x-ray tube. Large-Z effects such as line radiation, nuclear charge screening, and polarizational Bremsstrahlung are discussed.

Spectroscopic and neutron detection properties of rare earth and titanium doped LiAlO 2 single crystals

DOE PAGES

Dickens, Peter T.; Marcial, Jose; McCloy, John; ...

2017-05-17

In this study, LiAlO 2 crystals doped with rare-earth elements and Ti were produced by the CZ method and spectroscopic and neutron detection properties were investigated. Photoluminescence revealed no clear luminescent activation of LiAlO 2 by the rare-earth dopants though some interesting luminescence was observed from secondary phases within the crystal. Gamma-ray pulse height spectra collected using a 137Cs source exhibited only a Compton edge for the crystals. Neutron modeling using Monte Carlo N-Particle Transport Code revealed most neutrons used in the detection setup are thermalized, and while using natural lithium in the crystal growth, which contains 7.6% 6Li, amore » 10 mm Ø by 10 mm sample of LiAlO 2 has a 70.7% intrinsic thermal neutron capture efficiency. Furthermore, the pulse height spectra collected using a 241Am-Be neutron source demonstrated a distinct neutron peak.« less

Preliminary results with microchannel array plates employing curved microchannels to inhibit ion feedback. [for photon counters

NASA Technical Reports Server (NTRS)

Timothy, J. G.; Bybee, R. L.

1977-01-01

Up to now, microchannel array plates (MCPs) have been constructed with microchannels having a straight geometry and hence have been prone to ion-feedback instabilities at high operating potentials and high ambient pressures. This paper describes the performances of MCPs with curved (J and C configuration) microchannels to inhibit ion feedback. Plates with curved microchannels have demonstrated performances comparable to those of conventional channel electron multipliers with saturated output pulse-height distributions and modal gain values in excess of 10 to the 6th electrons/pulse.

Application of a pulsed laser for measurements of bathymetry and algal fluorescence.

NASA Technical Reports Server (NTRS)

Hickman, G. D.; Hogg, J. E.; Friedman, E. J.; Ghovanlou, A. H.

1973-01-01

The technique of measuring water depths with an airborne pulsed dye laser is studied, with emphasis on the degrading effect of some environmental and operational parameters on the transmitted and reflected laser signals. Extrapolation of measurements of laser stimulated fluorescence, performed as a function of both the algal cell concentration and the distance between the algae and the laser/receiver, indicate that a laser system operating from a height of 500 m should be capable of detecting chlorophyll concentrations as low as 1.0 mg/cu m.-

Observation of large-scale density cavities and parametric-decay instabilities in the high-altitude discrete auroral ionosphere under pulsed electromagnetic radiation.

PubMed

Wong, A Y; Chen, J; Lee, L C; Liu, L Y

2009-03-13

A large density cavity that measured 2000 km across and 500 km in height was observed by DEMETER and Formosat/COSMIC satellites in temporal and spatial relation to a new mode of propagation of electromagnetic (em) pulses between discrete magnetic field-aligned auroral plasmas to high altitudes. Recorded positive plasma potential from satellite probes is consistent with the expulsion of electrons in the creation of density cavities. High-frequency decay spectra support the concept of parametric instabilities fed by free energy sources.

Determination of cobalt in vegetable animal foodstuffs by differential pulse adsorptive voltammetry using alpha-benzil dioxime.

PubMed

Giroussi, S; Voulgaropoulos, A; Ayiannidis, A K; Golimowski, J; Janicki, M

1995-12-22

A selective and sensitive voltammetric method for the determination of cobalt in vegetable animal foodstuffs is developed. The method is based on the use of alpha-benzil dioxime (alpha-BD) as a chelating agent for differential pulse adsorptive stripping voltammetry (DPASV) and is free from zinc interferences. The influence of pH, time and alpha-BD concentration on the peak resolution and height are discussed. The method was successfully applied in some typical vegetable animal foodstuffs with R.S.D. < 6%.

Pulse pile-up identification and reconstruction for liquid scintillator based neutron detectors

NASA Astrophysics Data System (ADS)

Luo, X. L.; Modamio, V.; Nyberg, J.; Valiente-Dobón, J. J.; Nishada, Q.; de Angelis, G.; Agramunt, J.; Egea, F. J.; Erduran, M. N.; Ertürk, S.; de France, G.; Gadea, A.; González, V.; Goasduff, A.; Hüyük, T.; Jaworski, G.; Moszyński, M.; Di Nitto, A.; Palacz, M.; Söderström, P.-A.; Sanchis, E.; Triossi, A.; Wadsworth, R.

2018-07-01

The issue of pulse pile-up is frequently encountered in nuclear experiments involving high counting rates, which will distort the pulse shapes and the energy spectra. A digital method of off-line processing of pile-up pulses is presented. The pile-up pulses were firstly identified by detecting the downward-going zero-crossings in the first-order derivative of the original signal, and then the constituent pulses were reconstructed based on comparing the pile-up pulse with four models that are generated by combining pairs of neutron and γ standard pulses together with a controllable time interval. The accuracy of this method in resolving the pile-up events was investigated as a function of the time interval between two pulses constituting a pile-up event. The obtained results show that the method is capable of disentangling two pulses with a time interval among them down to 20 ns, as well as classifying them as neutrons or γ rays. Furthermore, the error of reconstructing pile-up pulses could be kept below 6% when successive peaks were separated by more than 50 ns. By applying the method in a high counting rate of pile-up events measurement of the NEutron Detector Array (NEDA), it was empirically found that this method can reconstruct the pile-up pulses and perform neutron- γ discrimination quite accurately. It can also significantly correct the distorted pulse height spectrum due to pile-up events.

A theoretical and experimental study on the pulsed laser dressing of bronze-bonded diamond grinding wheels

NASA Astrophysics Data System (ADS)

Deng, H.; Chen, G. Y.; Zhou, C.; Zhou, X. C.; He, J.; Zhang, Y.

2014-09-01

A series of theoretical analyses and experimental investigations were performed to examine a pulsed fiber-laser tangential profiling and radial sharpening technique for bronze-bonded diamond grinding wheels. The mechanisms for the pulsed laser tangential profiling and radial sharpening of grinding wheels were theoretically analyzed, and the four key processing parameters that determine the quality, accuracy, and efficiency of pulsed laser dressing, namely, the laser power density, laser spot overlap ratio, laser scanning track line overlap ratio, and number of laser scanning cycles, were proposed. Further, by utilizing cylindrical bronze wheels (without diamond grains) and bronze-bonded diamond grinding wheels as the experimental subjects, the effects of these four processing parameters on the removal efficiency and the surface smoothness of the bond material after pulsed laser ablation, as well as the effects on the contour accuracy of the grinding wheels, the protrusion height of the diamond grains, the sharpness of the grain cutting edges, and the graphitization degree of the diamond grains after pulsed laser dressing, were explored. The optimal values of the four key processing parameters were identified.

Analysis of the propagation of neutrons and gamma-rays from the fast neutron source reactor YAYOI

NASA Astrophysics Data System (ADS)

Yoshida, Shigeo; Murata, Isao; Nakagawa, Tsutomu; Saito, Isao

2011-10-01

The skyshine effect is crucial for designing appropriate shielding. To investigate the skyshine effect, the propagation of neutrons was measured and analyzed at the fast neutron source reactor YAYOI. Pulse height spectra and dose distributions of neutron and secondary gamma-ray were measured outside YAYOI, and analyzed with MCNP-5 and JENDL-3.3. Comparison with the experimental results showed good agreement. Also, a semi-empirical formula was successfully derived to describe the dose distribution. The formulae can be used to predict the skyshine effect at YAYOI, and will be useful for estimating the skyshine effect and designing the shield structure for fusion facilities.

Self-organized plasmonic metasurfaces for all-optical modulation

NASA Astrophysics Data System (ADS)

Della Valle, G.; Polli, D.; Biagioni, P.; Martella, C.; Giordano, M. C.; Finazzi, M.; Longhi, S.; Duò, L.; Cerullo, G.; Buatier de Mongeot, F.

2015-06-01

We experimentally demonstrate a self-organized metasurface with a polarization dependent transmittance that can be dynamically controlled by optical means. The configuration consists of tightly packed plasmonic nanowires with a large dispersion of width and height produced by the defocused ion-beam sputtering of a thin gold film supported on a silica glass. Our results are quantitatively interpreted according to a theoretical model based on the thermomodulational nonlinearity of gold and a finite-element numerical analysis of the absorption and scattering cross-sections of the nanowires. We found that the polarization sensitivity of the metasurface can be strongly enhanced by pumping with ultrashort laser pulses, leading to potential applications in ultrafast all-optical modulation and switching of light.

Two-pulse control of Raman scattering in liquid methanol: The dominance of classical nonlinear optical effects

NASA Astrophysics Data System (ADS)

Spanner, Michael; Brumer, Paul

2006-02-01

Experimental results on adaptive feedback control of transient (i.e., nonimpulsive) Stokes emission in liquid methanol [Pearson and Bucksbaum, Phys. Rev. Lett. 92, 243003 (2004)] are analyzed. In the experiment, a pump pulse comprising two frequency-shifted Gaussian pulses was used to control the ratio of two Stokes emission lines by varying the relative phase ϕL between the pulses. Extending the theory of stimulated Raman scattering to accommodate two coupled levels, we show that control of this type is possible, in the strongly driven regime, using Raman coupling alone. Control via variation of ϕL is shown to also result from self- and cross-phase-modulation of the pump and Stokes pulses as well as via the focused-beam geometry of the pump pulse. In all cases, the general control mechanism is nonlinear optical modulation between the pump and the Stokes pulse; no coherent quantum interference effects are involved. Finally, although the vibrational populations are affected by the same control mechanisms that affect the Stokes spectra, the ratio of the Stokes spectra peak heights does not directly reflect the ratio of the level populations, as was assumed in the experiment.

Periodic grain-boundary formation in a poly-Si thin film crystallized by linearly polarized Nd:YAG pulse laser with an oblique incident angle

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

Kaki, Hirokazu; Horita, Susumu

2005-01-01

We investigated the periodic grain-boundary formation in the polycrystalline silicon film crystallized by a linearly polarized Nd:YAG (where YAG is yttrium aluminum garnet) pulse laser with an oblique incident angle {theta}{sub i}=25 deg. , compared with the normal incident angle {theta}{sub i}=0. The alignment of the grain boundary was uncontrollable and fluctuated in the case of the oblique incident and large irradiation pulse number while that in the case of the normal incident was performed stably. It was found that the main cause for its low controllability was the nonphase matching between the periodic surface corrugation of the crystallized siliconmore » film and the periodic temperature profile induced by the laser irradiation. Also, it was found that, in the case of {theta}{sub i}=25 deg. , the dominant periodic width of the grain boundary depended on the pulse number N. That is, it was around {lambda}/(1+sin {theta}{sub i}) for small N{approx_equal}10 and {lambda}/(1-sin {theta}{sub i}) for large N{approx_equal}100 at the laser wavelength of {lambda}=532 nm. In order to explain this dependence, we proposed a model to take into account the periodic corrugation height proportional to the molten volume of the silicon film, the impediment in interference between the incident beam and diffracted beam on the irradiated surface due to the corrugation height, and the reduction of the liquid surface roughness during melting-crystallization process due to liquid-silicon viscosity.« less

Analysis of Pulsed Airborne Lidar Measurements of Atmospheric CO2 Column Absorption from 3-13 km Altitudes

NASA Technical Reports Server (NTRS)

Abshire, James B.; Weaver, Clark J.; Riris, Haris; Mao, Jianping; Sun, Xiaoli; Allan, Graham R.; Hasselbrack, William; Browell, Edward V.

2011-01-01

We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS space mission [1]. It uses two pulsed laser transmitters allowing simultaneous measurement of a CO2 absorption line in the 1575 nm band, O2 extinction in the Oxygen A-band, surface height and backscatter profile. The lasers are precisely stepped in wavelength across the CO2 line and an O2 line region during the measurement. The direct detection receiver measures the energies of the laser echoes from the surface along with the range profile of scattering in the path. The column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off-line signals via the integrated path differential absorption (IPDA) technique. The time of flight of the laser pulses is used to estimate the height of the scattering surface and to reject laser photons scattered in the atmosphere. We developed an airborne lidar to demonstrate an early version of the CO2 measurement from the NASA Glenn Lear-25 aircraft. The airborne lidar stepped the pulsed laser's wavelength across the selected CO2 line with 20 wavelength steps per scan. The line scan rate is 450 Hz, the laser pulse widths are 1 usec, and laser pulse energy is 24 uJ. The time resolved laser backscatter is collected by a 20 cm telescope, detected by a NIR photomultiplier and is recorded on every other reading by a photon counting system [2]. During August 2009 we made a series of 2.5 hour long flights and measured the atmospheric CO2 absorption and line shapes using the 1572.33 nm CO2 line. Measurements were made at stepped altitudes from 3-13 km over locations in the US, including the SGP ARM site in Oklahoma, central Illinois, north-eastern North Carolina, and over the Chesapeake Bay and the eastern shore of Virginia. Although the received signal energies were weaker than expected for ASCENDS, clear CO2 line shapes were observed at all altitudes, and some measurements were made through thin clouds. The Oklahoma and east coast flights were coordinated with a LaRC/ITT CO2 lidar on the LaRC UC-12 aircraft, and in-situ measurements were made using its CO2 sensor and radiosondes. We have conducted an analysis of the ranging and IPDA lidar measurements from these four flights. Most flights had 5-6 altitude steps with 200-300 seconds of recorded measurements per step. We used a cross-correlation approach to process the laser echo records. This was used to estimate the range to the scattering surface, to define the edges of the laser pulses and to determine echo pulse energy at each wavelength. We used a minimum mean square approach to fit an instrument response function and to solve for the best-fit CO2 absorption line shape. We then calculated the differential optical depth (DOD) of the fitted CO2 line. We computed its statistics at the various altitude steps, and compare them to the DODs calculated from spectroscopy based on HITRAN 2008 and the column conditions calculated from the airborne in-situ readings. The results show the lidar and in-situ measurements have very similar DOD change with altitude and greater than 10 segments per flight where the scatter in the lidar measurements are less than or equal to 1ppm. We also present the results from subsequent CO2 column absorption measurements, which were made with stronger detected signals during three flights on the NASA DC-8 over the southwestern US in during July 2010.

Aerobic Fitness for the Severely and Profoundly Mentally Retarded.

ERIC Educational Resources Information Center

Bauer, Dan

1981-01-01

The booklet discusses the aerobic fitness capacities of severely/profoundly retarded students and discusses approaches for improving their fitness. An initial section describes a method for determining the student's present fitness level on the basis of computations of height, weight, blood pressure, resting pulse, and Barach Index and Crampton…

LASER ALTIMETER CANOPY HEIGHT PROFILES: METHODS AND VALIDATION FOR CLOSED-CANOPY, BROADLEAF FORESTS. (R828309)

EPA Science Inventory

Abstract

Waveform-recording laser altimeter observations of vegetated landscapes provide a time-resolved measure of laser pulse backscatter energy from canopy surfaces and the underlying ground. Airborne laser altimeter waveform data was acquired using the Scanning Lid...

The association between pulse wave velocity and peripheral neuropathy in patients with type 2 diabetes mellitus.

PubMed

Tentolouris, Anastasios; Eleftheriadou, Ioanna; Grigoropoulou, Pinelopi; Kokkinos, Alexander; Siasos, Gerasimos; Ntanasis-Stathopoulos, Ioannis; Tentolouris, Nikolaos

2017-11-01

Diabetic peripheral neuropathy (DPN) is the most common diabetic complication, affecting up to half of the patients with type 2 diabetes mellitus (T2DM). Increased aortic stiffness, measured with the carotid-femoral pulse wave velocity (PWV), has been associated with incidence of cardiovascular disease independently of traditional risk factors. Previous data showed associations between risk factors for macroangiopathy and DPN in diabetes. However, the association between PWV and DPN is not well known. In this study we examined the association between PWV and presence as well as severity of DPN in subjects with T2DM. A total of 381 patients with T2DM were recruited. Participants were classified as having DPN and not having DPN. PWV was measured at the carotid-femoral segment with a non-invasive method using applanation tonometry. DPN was assessed by determination of the Neuropathy Symptom Score (NSS) and the Neuropathy Disability Score (NDS). A hundred and seven participants (28.1%) had DPN. Patients with DPN were significantly more often male and older, had longer diabetes duration, higher height, larger waist circumference, higher systolic arterial blood pressure (SBP) and higher PWV (all P<0.05). Furthermore, participants with DPN were treated more often with statins and had lower low density lipoprotein cholesterol; in addition, they were treated more often with antiplatelets, b-blockers and insulin than those without DPN. Univariative logistic regression analysis demonstrated that presence of DPN was significantly associated with age, male gender, longer diabetes duration, height, waist circumference, SBP, PWV, dyslipidemia, HbA1c, retinopathy, nephropathy and peripheral arterial disease. Multivariate logistic regression analysis, after adjustment for age, gender, waist circumference, SBP, nephropathy and use of b-blockers, demonstrated that the odds [OR (95% confidence intervals)] of peripheral neuropathy were associated significantly and independently only with diabetes duration [1.044 (1.009-1.081), P=0.013], height [1.075 (1.041-1.110), P<0.001], HbA1c [1.468 (1.164-1.851), P<0.001], PWV [1.174 (1.054-1.309), P=0.004], dyslipidemia [1.941 (1.015-3.713), P=0.045], retinopathy [4.426 (2.217-8.837), P<0.001] and peripheral arterial disease [4.658 (2.264-9.584), P<0.001]. In addition, multivariate linear regression analysis, after controlling for age, gender, diabetes duration, SBP, HbA1c and nephropathy, demonstrated that an increased NDS was significantly and independently associated with height [standardized regression coefficient (beta=0.229, P<0.001)], PWV (beta=0.197, P<0.001), retinopathy (beta=0.268, P<0.001) and peripheral arterial disease (beta=0.374, P<0.001). Increased PWV is associated strongly and independently not only with the presence but also with the severity of DPN in patients with T2DM, irrespective of known risk factors. Copyright © 2017 Elsevier Inc. All rights reserved.

Miniature high-let radiation spectrometer for space and avionics applications

NASA Astrophysics Data System (ADS)

Stassinopoulos, E. G.; Stauffer, Craig A.; Brucker, G. J.

This paper reports on the design and characterization of a small, low-power, and low-weight instrument, a High-LET Radiation Spectrometer (HiLRS), that measures energy deposited by heavy ions in microelectronic devices. The HiLRS operates on pulse-height analysis principles and is designed for space and avionics applications. The detector component in the instrument is based on large scale arrays of p-n junctions. In this system, the pulse amplitude from a particle hit is directly proportional to the particle LET. A prototype flight unit has been fabricated and calibrated using several heavy ions with varying LETs and protons with several energies. The unit has been delivered to the Ballistic Missile Defense Organization (BMDO) c/o the Air Force Research Laboratory in Albuquerque, NM, for integration into the military Space Technology Research Vehicle (STRV), a US-UK cooperative mission. Another version of HiLRS is being prepared for delivery in April to the Hubble Space Telescope (HST) project, to fly on the HST Orbital Systems Test (HOST) platform on a shuttle mission.

A new gamma ray imaging diagnostic for runaway electron studies at DIII-D

NASA Astrophysics Data System (ADS)

Cooper, C. M.; Pace, D. C.; Eidietis, N. W.; Paz-Soldan, C.; Commaux, N.; Shiraki, D.; Hollmann, E. M.; Moyer, R. A.; Risov, V.

2015-11-01

A new Gamma Ray Imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at DIII-D. The diagnostic is sensitive to 0.5 - 50 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE dissipation from pellet injection. The GRI consists of a lead ``pinhole camera'' mounted on the midplane with 11x11 counter-current tangential chords 20 cm wide that span the vessel. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE Bremsstrahlung radiation. Detectors operate in current saturation mode at 10 MHz, or the flux is attenuated for Pulse Height Analysis (PHA) capable of discriminating up to ~10k pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. Work supported by the US DOE under DE-AC05-00OR22725, DE-FG02-07ER54917 & DE-FC02-04ER54698.

Analysis of individual biological particles by mass spectrometry

NASA Technical Reports Server (NTRS)

Sinha, M. P.; Platz, R. M.; Vilker, V. L.; Friedlander, S. K.

1984-01-01

A method is developed for the detection and identification of biological particles introduced in aerosol form into a quadrupole mass spectrometer. The bacterial aerosol is generated by nebulizing an ethanol suspension. The particles are introduced into the ion source of the mass spectrometer in the form of a beam, where they are individually volatilized on a V-type rhenium filament and ionized by electron impaction. It is shown that the average intensity of a mass peak is obtained from the pulse height distribution of about a thousand ion pulses from different particles. Pseudomonas putida, Bacillus subtilis, and Bacillus cereus are used in the studies. Differences between the relative intensities of mass peaks in the spectra from P. putida and B. subtilis are found and may provide a method for differentiation of microorganisms. The results for the two species agree reasonably well with those reported by Kistemaker et al. (1975) and Schulten et al. (1973). However, there exist some differences between the two spectra in the high mass range due to the difference in the pyrolysis conditions.

Modeling the performance of a photon counting x-ray detector for CT: energy response and pulse pileup effects.

PubMed

Taguchi, Katsuyuki; Zhang, Mengxi; Frey, Eric C; Wang, Xiaolan; Iwanczyk, Jan S; Nygard, Einar; Hartsough, Neal E; Tsui, Benjamin M W; Barber, William C

2011-02-01

Recently, photon counting x-ray detectors (PCXDs) with energy discrimination capabilities have been developed for potential use in clinical computed tomography (CT) scanners. These PCXDs have great potential to improve the quality of CT images due to the absence of electronic noise and weights applied to the counts and the additional spectral information. With high count rates encountered in clinical CT, however, coincident photons are recorded as one event with a higher or lower energy due to the finite speed of the PCXD. This phenomenon is called a "pulse pileup event" and results in both a loss of counts (called "deadtime losses") and distortion of the recorded energy spectrum. Even though the performance of PCXDs is being improved, it is essential to develop algorithmic methods based on accurate models of the properties of detectors to compensate for these effects. To date, only one PCXD (model DXMCT-1, DxRay, Inc., Northridge, CA) has been used for clinical CT studies. The aim of that study was to evaluate the agreement between data measured by DXMCT-1 and those predicted by analytical models for the energy response, the deadtime losses, and the distorted recorded spectrum caused by pulse pileup effects. An energy calibration was performed using 99mTc (140 keV), 57Co (122 keV), and an x-ray beam obtained with four x-ray tube voltages (35, 50, 65, and 80 kVp). The DXMCT-1 was placed 150 mm from the x-ray focal spot; the count rates and the spectra were recorded at various tube current values from 10 to 500 microA for a tube voltage of 80 kVp. Using these measurements, for each pulse height comparator we estimated three parameters describing the photon energy-pulse height curve, the detector deadtime tau, a coefficient k that relates the x-ray tube current I to an incident count rate a by a = k x I, and the incident spectrum. The mean pulse shape of all comparators was acquired in a separate study and was used in the model to estimate the distorted recorded spectrum. The agreement between data measured by the DXMCT-1 and those predicted by the models was quantified by the coefficient of variation (COV), i.e., the root mean square difference divided by the mean of the measurement. Photon energy versus pulse height curves calculated with an analytical model and those measured using the DXMCT-1 were in agreement within 0.2% in terms of the COV. The COV between the output count rates measured and those predicted by analytical models was 2.5% for deadtime losses of up to 60%. The COVs between spectra measured and those predicted by the detector model were within 3.7%-7.2% with deadtime losses of 19%-46%. It has been demonstrated that the performance of the DXMCT-1 agreed exceptionally well with the analytical models regarding the energy response, the count rate, and the recorded spectrum with pulse pileup effects. These models will be useful in developing methods to compensate for these effects in PCXD-based clinical CT systems.

Assessing and Adapting LiDAR-Derived Pit-Free Canopy Height Model Algorithm for Sites with Varying Vegetation Structure

NASA Astrophysics Data System (ADS)

Scholl, V.; Hulslander, D.; Goulden, T.; Wasser, L. A.

2015-12-01

Spatial and temporal monitoring of vegetation structure is important to the ecological community. Airborne Light Detection and Ranging (LiDAR) systems are used to efficiently survey large forested areas. From LiDAR data, three-dimensional models of forests called canopy height models (CHMs) are generated and used to estimate tree height. A common problem associated with CHMs is data pits, where LiDAR pulses penetrate the top of the canopy, leading to an underestimation of vegetation height. The National Ecological Observatory Network (NEON) currently implements an algorithm to reduce data pit frequency, which requires two height threshold parameters, increment size and range ceiling. CHMs are produced at a series of height increments up to a height range ceiling and combined to produce a CHM with reduced pits (referred to as a "pit-free" CHM). The current implementation uses static values for the height increment and ceiling (5 and 15 meters, respectively). To facilitate the generation of accurate pit-free CHMs across diverse NEON sites with varying vegetation structure, the impacts of adjusting the height threshold parameters were investigated through development of an algorithm which dynamically selects the height increment and ceiling. A series of pit-free CHMs were generated using three height range ceilings and four height increment values for three ecologically different sites. Height threshold parameters were found to change CHM-derived tree heights up to 36% compared to original CHMs. The extent of the parameters' influence on modelled tree heights was greater than expected, which will be considered during future CHM data product development at NEON. (A) Aerial image of Harvard National Forest, (B) standard CHM containing pits, appearing as black speckles, (C) a pit-free CHM created with the static algorithm implementation, and (D) a pit-free CHM created through varying the height threshold ceiling up to 82 m and the increment to 1 m.

Method of making self-calibrated displacement measurements

DOEpatents

Pedersen, Herbert N.

1977-01-01

A method for monitoring the displacement of an object having an acoustically reflective surface at least partially submerged in an acoustically conductive medium. The reflective surface is designed to have a stepped interface responsive to an incident acoustic pulse to provide separate discrete reflected pulses to a receiving transducer. The difference in the time of flight of the reflected acoustic signals corresponds to the known step height and the time of travel of the signals to the receiving transducer provides a measure of the displacement of the object. Accordingly, the reference step length enables simultaneous calibration of each displacement measurement.

A laser system to remotely sense bird movements

NASA Technical Reports Server (NTRS)

Korschgen, C. E.; Green, W. L.; Seasholtz, R. G.

1983-01-01

The design and operation of a laser detection system for migrating birds are presented. A battery-powered class-III laser (operating at 904 nm, pulse-repetition rate 5 kHz, pulse duration 100 nsec, and peak power 25 W) and a photodiode receiver are mounted on poles at height 10 m and distance 850 m and equipped with 135-mm f/2.8 collimating lenses; beam diameter at the receiver is 1.7 m. The microprocessor-controlled system is found to detect the passing of an object as small as 30 sq cm in cross section at a distance of 425 m.

An improved arterial pulsation measurement system based on optical triangulation and its application in the traditional Chinese medicine

NASA Astrophysics Data System (ADS)

Wu, Jih-Huah; Lee, Wen-Li; Lee, Yun-Parn; Lin, Ching-Huang; Chiou, Ji-Yi; Tai, Chuan-Fu; Jiang, Joe-Air

2011-08-01

An improved arterial pulsation measurement (APM) system that uses three LED light sources and a CCD image sensor to measure pulse waveforms of artery is presented. The relative variations of the pulses at three measurement points near wrist joints can be determined by the APM system simultaneously. The height of the arterial pulsations measured by the APM system achieves a resolution of better than 2 μm. These pulsations contain useful information that can be used as diagnostic references in the traditional Chinese medicine (TCM) in the future.

Laser assisted bioprinting using a femtosecond laser with and without a gold transductive layer: a parametric study

NASA Astrophysics Data System (ADS)

Desrus, H.; Chassagne, B.; Catros, S.; Artiges, C.; Devillard, R.; Petit, S.; Deloison, F.; Fricain, J. C.; Guillemot, F.; Kling, R.

2016-03-01

Experimental results of femtosecond Laser Assisted Bioprinting (LAB) are reported on. Two set-up, used to print different model bioinks and keratinocytes cells line HaCaT, were studied: first one was using a femtosecond laser with low pulse energy and an absorbing gold layer, whereas the second one used high pulse energy enabling the removal of the absorbing layer. Printed drop diameter and resulting height of the bioink jet are then quantified as a function of the LAB parameters such as laser energy, focus spot location or numerical aperture.

Survey of the Effects of Exposure to 900 MHz Radiofrequency Radiation Emitted by a GSM Mobile Phone on the Pattern of Muscle Contractions in an Animal Model.

PubMed

Mortazavi, S M J; Rahimi, S; Talebi, A; Soleimani, A; Rafati, A

2015-09-01

The rapid development of wireless telecommunication technologies over the past decades, has led to significant changes in the exposure of the general public to electromagnetic fields. Nowadays, people are continuously exposed to different sources of electromagnetic fields such as mobile phones, mobile base stations, cordless phones, Wi-Fi routers, and power lines. Therefore, the last decade witnessed a rapidly growing concern about the possible health effects of exposure to electromagnetic fields emitted by these sources. In this study that was aimed at investigating the effects of exposure to radiofrequency (RF) radiation emitted by a GSM mobile phone on the pattern of contraction in frog's isolated gastrocnemius muscle after stimulation with single square pulses of 1V (1 Hz), pulse height of contractions, the time interval between two subsequent contractions and the latency period were measured. Our findings showed that the pulse height of contractions muscle could be affected by the exposure to electromagnetic fields. Especially, the latency period was effectively altered in RF-exposed samples. However, none of the experiments could show an alteration in the time interval between two subsequent contractions after exposure to electromagnetic fields. These findings support early reports which indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians including the effects on the pattern of muscle extractions.

The Laser Vegetation Imaging Sensor: a medium-altitude, digitisation-only, airborne laser altimeter for mapping vegetation and topography

NASA Astrophysics Data System (ADS)

Blair, J. Bryan; Rabine, David L.; Hofton, Michelle A.

The Laser Vegetation Imaging Sensor (LVIS) is an airborne, scanning laser altimeter, designed and developed at NASA's Goddard Space Flight Center (GSFC). LVIS operates at altitudes up to 10 km above ground, and is capable of producing a data swath up to 1000 m wide nominally with 25-m wide footprints. The entire time history of the outgoing and return pulses is digitised, allowing unambiguous determination of range and return pulse structure. Combined with aircraft position and attitude knowledge, this instrument produces topographic maps with dm accuracy and vertical height and structure measurements of vegetation. The laser transmitter is a diode-pumped Nd:YAG oscillator producing 1064 nm, 10 ns, 5 mJ pulses at repetition rates up to 500 Hz. LVIS has recently demonstrated its ability to determine topography (including sub-canopy) and vegetation height and structure on flight missions to various forested regions in the US and Central America. The LVIS system is the airborne simulator for the Vegetation Canopy Lidar (VCL) mission (a NASA Earth remote sensing satellite due for launch in year 2000), providing simulated data sets and a platform for instrument proof-of-concept studies. The topography maps and return waveforms produced by LVIS provide Earth scientists with a unique data set allowing studies of topography, hydrology, and vegetation with unmatched accuracy and coverage.

Demon voltammetry and analysis software: Analysis of cocaine-induced alterations in dopamine signaling using multiple kinetic measures

PubMed Central

Yorgason, Jordan T.; España, Rodrigo A.; Jones, Sara R.

2011-01-01

The fast sampling rates of fast scan cyclic voltammetry make it a favorable method for measuring changes in brain monoamine release and uptake kinetics in slice, anesthetized, and freely moving preparations. The most common analysis technique for evaluating changes in dopamine signaling uses well-established Michaelis-Menten kinetic methods that can accurately model dopamine release and uptake parameters across multiple experimental conditions. Nevertheless, over the years, many researchers have turned to other measures to estimate changes in dopamine release and uptake, yet to our knowledge no systematic comparison amongst these measures has been conducted. To address this lack of uniformity in kinetic analyses, we have created the Demon Voltammetry and Analysis software suite, which is freely available to academic and non-profit institutions. Here we present an explanation of the Demon Acquisition and Analysis features, and demonstrate its utility for acquiring voltammetric data under in vitro, in vivo anesthetized, and freely moving conditions. Additionally, the software was used to compare the sensitivity of multiple kinetic measures of release and uptake to cocaine-induced changes in electrically evoked dopamine efflux in nucleus accumbens core slices. Specifically, we examined and compared tau, full width at half height, half-life, T20, T80, slope, peak height, calibrated peak dopamine concentration, and area under the curve to the well-characterized Michaelis-Menten parameters, dopamine per pulse, maximal uptake rate, and apparent affinity. Based on observed results we recommend tau for measuring dopamine uptake and calibrated peak dopamine concentration for measuring dopamine release. PMID:21392532

Evidence of negative leaders which precede fast rise ICC pulses of upward

NASA Astrophysics Data System (ADS)

Yoshida, S.; Akita, M.; Morimoto, T.; Ushio, T.; Kawasaki, Z.; Wang, D.; Takagi, N.

2008-12-01

During winter thunderstorm season in Japan, a lightning observation campaign was conducted with using a VHF broadband digital interferometer (DITF), a capacitive antenna, and Rogowski coils to study the charge transfer mechanism associated with ICC pulses of upward lightning. All the detection systems recorded one upward negative lightning stroke hitting a lightning protection tower. The upward lightning consists of only the Initial Stage (IS) with one upward positive leader and six ICC pulses. The six ICC pulses are sub-classified clearly into two types according to current pulse shapes. The type 1 ICC pulses have a higher geometric mean (GM) current peak of 17 kA and a shorter GM 10-90% risetime of 8.9 μs, while the type 2 ICC pulses have a lower GM current peak of 0.34 kA and longer GM 10-90% risetime of 55 μs. The type 1 ICC pulses have the preceding negative leaders connecting to the channel of the continuing current, while the type 2 ICC pulses have no clear preceding negative leader. These negative leaders prior to the type 1 ICC pulses probably caused the current increases of the ICC pulses, which means that the negative leaders created the channels for the ICC pulses. The height of the space charge transferred by one of the type 1 ICC pulses was estimated about 700 m above sea level at most. This observation result is the first evidence to show explicitly the existence of the negative leaders prior to the fast rise ICC pulse. Furthermore, the result shows that space charge could exist at a low attitude such as 700 m above sea level. This fact is one of the reasons why upward lightning occurs even from rather low structures during winter thunderstorm season in Japan.

First principles pulse pile-up balance equation and fast deterministic solution

NASA Astrophysics Data System (ADS)

Sabbatucci, Lorenzo; Fernández, Jorge E.

2017-08-01

Pulse pile-up (PPU) is an always present effect which introduces a distortion into the spectrum measured with radiation detectors and that worsen with the increasing emission rate of the radiation source. It is fully ascribable to the pulse handling circuitry of the detector and it is not comprised in the detector response function which is well explained by a physical model. The PPU changes both the number and the height of the recorded pulses, which are related, respectively, with the number of detected particles and their energy. In the present work, it is derived a first principles balance equation for second order PPU to obtain a post-processing correction to apply to X-ray measurements. The balance equation is solved for the particular case of rectangular pulse shape using a deterministic iterative procedure for which it will be shown the convergence. The proposed method, deterministic rectangular PPU (DRPPU), requires minimum amount of information and, as example, it is applied to a solid state Si detector with active or off-line PPU suppression circuitry. A comparison shows that the results obtained with this fast and simple approach are comparable to those from the more sophisticated procedure using precise detector pulse shapes.

Multi-beam laser altimeter

NASA Technical Reports Server (NTRS)

Bufton, Jack L.; Harding, David J.; Ramos-Izquierdo, Luis

1993-01-01

Laser altimetry provides a high-resolution, high-accuracy method for measurement of the elevation and horizontal variability of Earth-surface topography. The basis of the measurement is the timing of the round-trip propagation of short-duration pulses of laser radiation between a spacecraft and the Earth's surface. Vertical resolution of the altimetry measurement is determined primarily by laser pulsewidth, surface-induced spreading in time of the reflected pulse, and the timing precision of the altimeter electronics. With conventional gain-switched pulses from solid-state lasers and sub-nsec resolution electronics, sub-meter vertical range resolution is possible from orbital attitudes of several hundred kilometers. Horizontal resolution is a function of laser beam footprint size at the surface and the spacing between successive laser pulses. Laser divergence angle and altimeter platform height above the surface determine the laser footprint size at the surface, while laser pulse repetition-rate, laser transmitter beam configuration, and altimeter platform velocity determine the space between successive laser pulses. Multiple laser transitters in a singlaltimeter instrument provide across-track and along-track coverage that can be used to construct a range image of the Earth's surface. Other aspects of the multi-beam laser altimeter are discussed.

A Geant4 evaluation of the Hornyak button and two candidate detectors for the TREAT hodoscope

NASA Astrophysics Data System (ADS)

Fu, Wenkai; Ghosh, Priyarshini; Harrison, Mark J.; McGregor, Douglas S.; Roberts, Jeremy A.

2018-05-01

The performance of traditional Hornyak buttons and two proposed variants for fast-neutron hodoscope applications was evaluated using Geant4. The Hornyak button is a ZnS(Ag)-based device previously deployed at the Idaho National Laboratory's TRansient REActor Test Facility (better known as TREAT) for monitoring fast neutrons emitted during pulsing of fissile fuel samples. Past use of these devices relied on pulse-shape discrimination to reduce the significant levels of background Cherenkov radiation. Proposed are two simple designs that reduce the overall light guide mass (here, polymethyl methacrylate or PMMA), employ silicon photomultipliers (SiPMs), and can be operated using pulse-height discrimination alone to eliminate background noise to acceptable levels. Geant4 was first used to model a traditional Hornyak button, and for assumed, hodoscope-like conditions, an intrinsic efficiency of 0.35% for mono-directional fission neutrons was predicted. The predicted efficiency is in reasonably good agreement with experimental data from the literature and, hence, served to validate the physics models and approximations employed. Geant4 models were then developed to optimize the materials and geometries of two alternatives to the Hornyak button, one based on a homogeneous mixture of ZnS(Ag) and PMMA, and one based on alternating layers of ZnS(Ag) and PMMA oriented perpendicular to the incident neutron beam. For the same radiation environment, optimized, 5-cm long (along the beam path) devices of the homogeneous and layered designs were predicted to have efficiencies of approximately 1.3% and 3.3%, respectively. For longer devices, i.e., lengths larger than 25 cm, these efficiencies were shown to peak at approximately 2.2% and 5.9%, respectively. Moreover, both designs were shown to discriminate Cherenkov noise intrinsically by using an appropriate pulse-height discriminator level, i.e., pulse-shape discrimination is not needed for these devices.

A Geant4 evaluation of the Hornyak button and two candidate detectors for the TREAT hodoscope

DOE PAGES

Fu, Wenkai; Ghosh, Priyarshini; Harrison, Mark; ...

2018-02-05

The performance of traditional Hornyak buttons and two proposed variants for fast-neutron hodoscope applications was evaluated using Geant4. The Hornyak button is a ZnS(Ag)-based device previously deployed at the Idaho National Laboratory's TRansient REActor Test Facility (better known as TREAT) for monitoring fast neutrons emitted during pulsing of fissile fuel samples. Past use of these devices relied on pulse-shape discrimination to reduce the significant levels of background Cherenkov radiation. Proposed are two simple designs that reduce the overall light guide mass (here, polymethyl methacrylate or PMMA), employ silicon photomultipliers (SiPMs), and can be operated using pulse-height discrimination alone to eliminatemore » background noise to acceptable levels. Geant4 was first used to model a traditional Hornyak button, and for assumed, hodoscope-like conditions, an intrinsic efficiency of 0.35% for mono-directional fission neutrons was predicted. The predicted efficiency is in reasonably good agreement with experimental data from the literature and, hence, served to validate the physics models and approximations employed. Geant4 models were then developed to optimize the materials and geometries of two alternatives to the Hornyak button, one based on a homogeneous mixture of ZnS(Ag) and PMMA, and one based on alternating layers of ZnS(Ag) and PMMA oriented perpendicular to the incident neutron beam. For the same radiation environment, optimized, 5-cm long (along the beam path) devices of the homogeneous and layered designs were predicted to have efficiencies of approximately 1.3% and 3.3%, respectively. For longer devices, i.e., lengths larger than 25 cm, these efficiencies were shown to peak at approximately 2.2% and 5.9%, respectively. Furthermore, both designs were shown to discriminate Cherenkov noise intrinsically by using an appropriate pulse-height discriminator level, i.e., pulse-shape discrimination is not needed for these devices.« less

ROSAT observations of pulsed soft X-ray emission from PSR 1055-52

NASA Technical Reports Server (NTRS)

Oegelman, Hakki; Finley, John P.

1993-01-01

Utilizing the position-sensitive proportional counter and the high-resolution imager aboard the orbiting X-ray observatory ROSAT, we have detected pulsations at the radio period from the pulsar PSR 1055-52. The pulse shapes are energy-dependent and show a transition at about 0.5 keV where the phase angle of the pulse peak changes by about -120 deg and the pulsed fraction increases from 11 percent to 63 percent toward larger energies. Simple spectral models are found to be unsatisfactory, while multicomponent models, such as a soft blackbody and hard power-law tail, yield better fits to the pulse-height data. The hard power-law tail is consistent with the extension of the recently reported EGRET results and may indicate a common emission mechanism for the X-ray through GeV gamma-ray regime. The soft blackbody component with T(infinity) = (7.5 +/- 0.6) x 10 exp 5 K, if interpreted as the initial cooling of a neutron star, is consistent with standard cooling models and does not require the presence of exotic components.

Isolated terawatt attosecond hard X-ray pulse generated from single current spike.

PubMed

Shim, Chi Hyun; Parc, Yong Woon; Kumar, Sandeep; Ko, In Soo; Kim, Dong Eon

2018-05-10

Isolated terawatt (TW) attosecond (as) hard X-ray pulse is greatly desired for four-dimensional investigations of natural phenomena with picometer spatial and attosecond temporal resolutions. Since the demand for such sources is continuously increasing, the possibility of generating such pulse by a single current spike without the use of optical or electron delay units in an undulator line is addressed. The conditions of a current spike (width and height) and a modulation laser pulse (wavelength and power) is also discussed. We demonstrate that an isolated TW-level as a hard X-ray can be produced by a properly chosen single current spike in an electron bunch with simulation results. By using realistic specifications of an electron bunch of the Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL), we show that an isolated, >1.0 TW and ~36 as X-ray pulse at 12.4 keV can be generated in an optimized-tapered undulator line. This result opens a new vista for current XFEL operation: the attosecond XFEL.

Neutron Spectroscopy for pulsed beams with frame overlap using a double time-of-flight technique

NASA Astrophysics Data System (ADS)

Harrig, K. P.; Goldblum, B. L.; Brown, J. A.; Bleuel, D. L.; Bernstein, L. A.; Bevins, J.; Harasty, M.; Laplace, T. A.; Matthews, E. F.

2018-01-01

A new double time-of-flight (dTOF) neutron spectroscopy technique has been developed for pulsed broad spectrum sources with a duty cycle that results in frame overlap, where fast neutrons from a given pulse overtake slower neutrons from previous pulses. Using a tunable beam at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory, neutrons were produced via thick-target breakup of 16 MeV deuterons on a beryllium target in the cyclotron vault. The breakup spectral shape was deduced from a dTOF measurement using an array of EJ-309 organic liquid scintillators. Simulation of the neutron detection efficiency of the scintillator array was performed using both GEANT4 and MCNP6. The efficiency-corrected spectral shape was normalized using a foil activation technique to obtain the energy-dependent flux of the neutron beam at zero degrees with respect to the incoming deuteron beam. The dTOF neutron spectrum was compared to spectra obtained using HEPROW and GRAVEL pulse height spectrum unfolding techniques. While the unfolding and dTOF results exhibit some discrepancies in shape, the integrated flux values agree within two standard deviations. This method obviates neutron time-of-flight spectroscopy challenges posed by pulsed beams with frame overlap and opens new opportunities for pulsed white neutron source facilities.

Interaction of Lightning Electromagnetic Pulse with the Ionosphere as Inferred from Wideband Measurements and Modeling

NASA Astrophysics Data System (ADS)

Somu, Vijaya Bhaskar

Apparent ionospheric reflection heights estimated using the zero-to-zero and peak-to-peak methods to measure skywave delay relative to the groundwave were compared for 108 first and 124 subsequent strokes observed at LOG in 2009. For either metric there was a considerable decrease in average re ection height for subsequent strokes relative to first strokes. Median uncertainties in daytime re ection heights did not exceed 0.7 km. The standard errors in mean re ection heights were less than 3% of the mean value. Apparent changes in re ection height (estimated using the peak-to-peak method) within individual ashes for 54 daytime and 11 nighttime events at distances ranging from 50 km to 330 km were compared. For daytime conditions, the majority of the ashes showed a monotonic decrease in re ection height. For nighttime ashes, the monotonic decrease was found to be considerably less frequent. The apparent ionospheric re ection height tends to increase with return-stroke peak current. In order to increase the sample size for nighttime conditions, additional data for 43 nighttime flashes observed at LOG in 2014 were analyzed. The "fast-break-point" method of measuring skywave delay (McDonald et al., 1979) was additionally used. The 2014 results for return strokes are generally consistent with the 2009 results. The 2014 data were also used for estimating ionospheric re ection heights for elevated sources (6 CIDs and 3 PB pulses) using the double-skywave feature. The results were compared with re ection heights estimated for corresponding return strokes (if any), and fairly good agreement was generally found. It has been shown, using two different FDTD simulation codes, that the observed differences in re ection height cannot be explained by the difference in the frequency content of first and subsequent return-stroke currents. FDTD simulations showed that within 200 km the re ection heights estimated using the peak-to-peak method are close to the hOE parameter of the ionospheric profile for both daytime and nighttime conditions and for both first and second skywaves. The TL model was used to estimate the radial extent of elves produced by the interaction of LEMP with the ionosphere as a function of return-stroke peak current. For a peak current of 100 kA and the speed equal to one-half of the speed of light, the expected radius of elves is 157 km. Skywaves associated with 24 return strokes in 6 lightning ashes triggered at CB in 2015 and recorded at LOG (at a distance of 45 km from CB) were not found for any of the strokes recorded. In contrast, natural-lightning strokes do produce skywaves at comparable distances. One possible reason is the difference in the higher-frequency content (field waveforms for triggered lightning are more narrow than for natural lightning).

On-line computer system for use with low- energy nuclear physics experiments is reported

NASA Technical Reports Server (NTRS)

Gemmell, D. S.

1969-01-01

Computer program handles data from low-energy nuclear physics experiments which utilize the ND-160 pulse-height analyzer and the PHYLIS computing system. The program allows experimenters to choose from about 50 different basic data-handling functions and to prescribe the order in which these functions will be performed.

A method to evaluate hydraulic fracture using proppant detection.

PubMed

Liu, Juntao; Zhang, Feng; Gardner, Robin P; Hou, Guojing; Zhang, Quanying; Li, Hu

2015-11-01

Accurate determination of the proppant placement and propped fracture height are important for evaluating and optimizing stimulation strategies. A technology using non-radioactive proppant and a pulsed neutron gamma energy spectra logging tool to determine the placement and height of propped fractures is proposed. Gd2O3 was incorporated into ceramic proppant and a Monte Carlo method was utilized to build the logging tools and formation models. Characteristic responses of the recorded information of different logging tools to fracture widths, proppant concentrations and influencing factors were studied. The results show that Gd capture gamma rays can be used to evaluate propped fractures and it has higher sensitivity to the change of fracture width and traceable proppant content compared with the exiting non-radioactive proppant evaluation techniques and only an after-fracture measurement is needed for the new method; The changes in gas saturation and borehole size have a great impact on determining propped fractures when compensated neutron and pulsed neutron capture tool are used. A field example is presented to validate the application of the new technique. Copyright © 2015 Elsevier Ltd. All rights reserved.

Multiplication and Presence of Shielding Material from Time-Correlated Pulse-Height Measurements of Subcritical Plutonium Assemblies

DOE PAGES

Monterial, Mateusz; Marleau, Peter; Paff, Marc; ...

2017-01-20

Here, we present the results from the first measurements of the Time-Correlated Pulse-Height (TCPH) distributions from 4.5 kg sphere of α-phase weapons-grade plutonium metal in five configurations: bare, reflected by 1.27 cm and 2.54 cm of tungsten, and 2.54 cm and 7.62 cm of polyethylene. A new method for characterizing source multiplication and shielding configuration is also demonstrated. The method relies on solving for the underlying fission chain timing distribution that drives the spreading of the measured TCPH distribution. We found that a gamma distribution fits the fission chain timing distribution well and that the fit parameters correlate with bothmore » multiplication (rate parameter) and shielding material types (shape parameter). The source-to-detector distance was another free parameter that we were able to optimize, and proved to be the most well constrained parameter. MCNPX-PoliMi simulations were used to complement the measurements and help illustrate trends in these parameters and their relation to multiplication and the amount and type of material coupled to the subcritical assembly.« less

Measurement and validation of benchmark-quality thick-target tungsten X-ray spectra below 150 kVp.

PubMed

Mercier, J R; Kopp, D T; McDavid, W D; Dove, S B; Lancaster, J L; Tucker, D M

2000-11-01

Pulse-height distributions of two constant potential X-ray tubes with fixed anode tungsten targets were measured and unfolded. The measurements employed quantitative alignment of the beam, the use of two different semiconductor detectors (high-purity germanium and cadmium-zinc-telluride), two different ion chamber systems with beam-specific calibration factors, and various filter and tube potential combinations. Monte Carlo response matrices were generated for each detector for unfolding the pulse-height distributions into spectra incident on the detectors. These response matrices were validated for the low error bars assigned to the data. A significant aspect of the validation of spectra, and a detailed characterization of the X-ray tubes, involved measuring filtered and unfiltered beams at multiple tube potentials (30-150 kVp). Full corrections to ion chamber readings were employed to convert normalized fluence spectra into absolute fluence spectra. The characterization of fixed anode pitting and its dominance over exit window plating and/or detector dead layer was determined. An Appendix of tabulated benchmark spectra with assigned error ranges was developed for future reference.

Multiplication and Presence of Shielding Material from Time-Correlated Pulse-Height Measurements of Subcritical Plutonium Assemblies

NASA Astrophysics Data System (ADS)

Monterial, Mateusz; Marleau, Peter; Paff, Marc; Clarke, Shaun; Pozzi, Sara

2017-04-01

We present the results from the first measurements of the Time-Correlated Pulse-Height (TCPH) distributions from 4.5 kg sphere of α-phase weapons-grade plutonium metal in five configurations: bare, reflected by 1.27 cm and 2.54 cm of tungsten, and 2.54 cm and 7.62 cm of polyethylene. A new method for characterizing source multiplication and shielding configuration is also demonstrated. The method relies on solving for the underlying fission chain timing distribution that drives the spreading of the measured TCPH distribution. We found that a gamma distribution fits the fission chain timing distribution well and that the fit parameters correlate with both multiplication (rate parameter) and shielding material types (shape parameter). The source-to-detector distance was another free parameter that we were able to optimize, and proved to be the most well constrained parameter. MCNPX-PoliMi simulations were used to complement the measurements and help illustrate trends in these parameters and their relation to multiplication and the amount and type of material coupled to the subcritical assembly.

Investigation of large format microchannel plate Z configurations

NASA Technical Reports Server (NTRS)

Siegmund, O. H. W.; Coburn, K.; Malina, R. F.

1985-01-01

The performance of triplet (Z) stacks of microchannel plates (MCPs) has been studied as a part of the instrument development for the Extreme Ultraviolet Explorer (EUVE) satellite mission. Relatively large MCPs with a 60-mm diameter and having a large 80:1 channel length to diameter (L:D) ratio were used in several configurations. The MCPs were used in the EUVE prototype imaging detector to provide more than 512 x 512 pixels with low image distortion (less than 1 percent). The gain and pulse height characteristics of the MCPs were examined, showing that both high gains (more than 2 x 10 to the 7th) and tight output pulse height distributions (less than 30 percent FWHM) may be achieved. Simple distribution techniques have also allowed low intrinsic background event rates (less than 0.15 events per sq cm/s) to be obtained. Variation of the quantum efficiency of the MCPs over the wavelength range 160-1216 A has been investigated for a range of angles of incidence. The effect of temperature variations on MCP operating characteristics has also been evaluated.

The Voyager Cosmic Ray Experiment

NASA Technical Reports Server (NTRS)

Stilwell, D. E.; Davis, W. D.; Joyce, R. M.; Mcdonald, F. B.; Trainor, J. H.; Althouse, W. E.; Cummings, A. C.; Garrard, T. L.; Stone, E. C.; Vogt, R. E.

1979-01-01

The Voyager Cosmic Ray Experiment includes seven dE/dx-E telescopes to measure the energy and charge of particles with atomic numbers from 1 to 26 in the energy range 1-500 MeV/nucleon and to measure electron energy in the range from 3 to 110 MeV. Isotopic composition of hydrogen through sulfur in the range up to 75 Mev/nucleon can also be resolved. The electronic systems include a dual-gain, charge sensitive preamplifier, 4096-channel pulse height analyzers for three parameter analysis of selected events, and an event type readout polling scheme to maximize the use of available telemetry space and to enhance the occurrence of rare events in the data. Details of the detector, electronic and mechanical design are presented.

Significant variation from a 1/R-squared potential in the cumulative flux determined from the Giotto Comet Halley Dust Impact Experiment

NASA Technical Reports Server (NTRS)

Alexander, W. M.; Goad, S.; Mcdonald, R. A.; Tanner, W. G., Jr.; Pollock, J. J.

1989-01-01

The Dust Impact Detection System (DIDSY) aboard the Giotto spacecraft provided the information on the dust flux, mass spectrum, and cumulative mass distribution flux in the coma of Comet Halley. Analysis of discrete pulse height data of cometary particles for the mass range of particles between 4.0 x 10 to the -10th g and 6.0 x 10 to the -6th g registered by the Giotto DIDSY detectors 2, 3, and 4 has been completed, and a cumulative flux has been determined for this size range of particles. Inside the cometopause, anomalous peaks have been identified as deviation from a 1/R-squared curve in both pre- and postencounter measurements.

Partial analysis of the flare-prominence of 30 April 1974

NASA Technical Reports Server (NTRS)

Wu, S. T.; Dryer, M.; Mcintosh, P. S.; Reichmann, E.

1975-01-01

A portion of an east limb flare-prominence observed in H-alpha light is analyzed. Following rapid achievement of a maximum mass-ejection velocity of about 375 km/s, the ascending prominence reached a height of at least 200,000 km. A one-dimensional time-dependent hydrodynamic theory is used to compute the total mass and energy ejected during this part of the event. Theoretical aspects of the coronal response are discussed. It is concluded that a moderate temperature and density pulse (factors of ten and two, respectively) for a duration of only 3 min is sufficient for an acceptable simulation of the H-alpha observations and the likely coronal response to the ascending prominence and flare-related ejections.

Exposure to Radiofrequency Radiation Emitted from Common Mobile Phone Jammers Alters the Pattern of Muscle Contractions: an Animal Model Study.

PubMed

Rafati, A; Rahimi, S; Talebi, A; Soleimani, A; Haghani, M; Mortazavi, S M J

2015-09-01

The rapid growth of wireless communication technologies has caused public concerns regarding the biological effects of electromagnetic radiations on human health. Some early reports indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians such as the alterations of the pattern of muscle extractions. This study is aimed at investigating the effects of exposure to radiofrequency (RF) radiation emitted from mobile phone jammers on the pulse height of contractions, the time interval between two subsequent contractions and the latency period of frog's isolated gastrocnemius muscle after stimulation with single square pulses of 1V (1 Hz). Frogs were kept in plastic containers in a room. Animals in the jammer group were exposed to radiofrequency (RF) radiation emitted from a common Jammer at a distance of 1m from the jammer's antenna for 2 hours while the control frogs were only sham exposed. Then animals were sacrificed and isolated gastrocnemius muscles were exposed to on/off jammer radiation for 3 subsequent 10 minute intervals. Isolated gastrocnemius muscles were attached to the force transducer with a string. Using a PowerLab device (26-T), the pattern of muscular contractions was monitored after applying single square pulses of 1V (1 Hz) as stimuli. The findings of this study showed that the pulse height of muscle contractions could not be affected by the exposure to electromagnetic fields. However, the latency period was effectively altered in RF-exposed samples. However, none of the experiments could show an alteration in the time interval between two subsequent contractions after exposure to electromagnetic fields. These findings support early reports which indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians including the effects on the pattern of muscle extractions.

A study of marine stratocumulus using lidar and other FIRE aircraft observations

NASA Technical Reports Server (NTRS)

Jensen, Jorgen B.; Lenschow, Donald H.

1990-01-01

The National Center for Atmospheric Research (NCAR) airborne infrared lidar system (NAILS) used in the 1987 First ISCCP Regional Experiment (FIRE) off the coast of California is a 10.6 microns wavelength carbon dioxide lidar system constructed by Ron Schwiesow and co-workers at NCAR. The lidar is particularly well suited for detailed observations of cloud shapes; i.e., height of cloud top (when flying above cloud and looking down) and cloud base (when flying below cloud and looking up) along the flight path. A brief summary of the lidar design characteristics is given. The lidar height resolution of plus or minus 3 m allows for the distance between the aircraft and cloud edge to be determined with this accuracy; however, the duration of the emitted pulse is approximately 3 microseconds, which corresponds to a 500 m pulse length. Therefore, variations in backscatter intensities within the clouds can normally not be resolved. Hence the main parameter obtainable from the lidar is distance to cloud; in some cases the cloud depth can also be determined. During FIRE the lidar was operational on 7 of the 10 Electra flights, and data were taken when the distance between cloud and aircraft (minimum range) was at least 500 m. The lidar was usually operated at 8 Hz, which at a flight speed of 100 m s(-1) translates into a horizontal resolution of about 12 m. The backscatter as function of time (equivalent to distance) for each laser pulse is stored in digital form on magnetic tape. Currently, three independent variables are available to the investigators on the FIRE Electra data tapes: lidar range to cloud, strength of return (relative power), and pulse width of return, which is related to penetration depth.

Properties of the unusually short pulse sequences occurring prior to the first strokes of negative cloud-to-ground lightning flashes

NASA Astrophysics Data System (ADS)

Kolmasova, Ivana; Santolik, Ondrej; Farges, Thomas; Rison, William; Lan, Radek; Uhlir, Ludek

2014-05-01

We analyze pulse sequences occurring prior to first return strokes of negative cloud-to-ground lightning flashes. The magnetic-field waveforms are measured close to the thunderstorm using a broad-band analyzer with a sampling interval of 12.5 ns. The electric-field waveforms are measured at the distance of ~ 400 km using an analyzer with a sampling interval of 80 ns. The sequence is usually composed of three parts. It begins with a larger pulse train which is believed to be connected with initial breakdown processes. The train of preliminary breakdown pulses ("B" part) is followed by a relatively low and irregular pulse activity ("I" part), which is sometimes missing. The sequence ends with a pulse train attributed to the stepped leader ("L" part). We recognize two different patterns ("B-I-L" and "B-L" types) in recorded waveforms. For the first time, we analyze the time evolution of the pulse amplitudes in the "B" part of "B-I-L" type sequences. The pulse amplitude is decreasing on average by 34% of the maximum value within a given train. We observe an unusually short duration of sequences. This is probably linked to a low height of the thundercloud. Another possible explanation may be based on an untypical precipitation mix resulting in faster steeped leaders.

Video monitoring reveals pulsating vents and propagation path of fissure eruption during the March 2011 Pu'u 'Ō'ō eruption, Kilauea volcano

NASA Astrophysics Data System (ADS)

Witt, Tanja; Walter, Thomas R.

2017-01-01

Lava fountains are a common eruptive feature of basaltic volcanoes. Many lava fountains result from fissure eruptions and are associated with the alignment of active vents and rising gas bubbles in the conduit. Visual reports suggest that lava fountain pulses may occur in chorus at adjacent vents. The mechanisms behind such a chorus of lava fountains and the underlying processes are, however, not fully understood. The March 2011 eruption at Pu'u 'Ō'ō (Kilauea volcano) was an exceptional fissure eruption that was well monitored and could be closely approached by field geologists. The fissure eruption occurred along groups of individual vents aligned above the feeding dyke. We investigate video data acquired during the early stages of the eruption to measure the height, width and velocity of the ejecta leaving eight vents. Using a Sobel edge-detection algorithm, the activity level of the lava fountains at the vents was determined, revealing a similarity in the eruption height and frequency. Based on this lava fountain time series, we estimate the direction and degree of correlation between the different vents. We find that the height and velocity of the eruptions display a small but systematic shift in time along the vents, indicating a lateral migration of lava fountaining at a rate of 11 m/s from W to E. This finding is in agreement with a propagation model of a pressure wave originating at the Kilauea volcano and propagating through the dyke at 10 m/s from W to E. Based on this approach from videos only 30 s long, we are able to obtain indirect constraints on the physical dyke parameters, with important implications for lateral magma flow processes at depth. This work shows that the recording and analysis of video data provide important constraints on the mechanisms of lava fountain pulses. Even though the video sequence is short, it allows for the confirmation of the magma propagation direction and a first-order estimation of the dyke dimensions.

Resonant-cavity apparatus for cytometry or particle analysis

DOEpatents

Gourley, Paul L.

1998-01-01

A resonant-cavity apparatus for cytometry or particle analysis. The apparatus comprises a resonant optical cavity having an analysis region within the cavity for containing one or more biological cells or dielectric particles to be analyzed. In the presence of a cell or particle, a light beam in the form of spontaneous emission or lasing is generated within the resonant optical cavity and is encoded with information about the cell or particle. An analysis means including a spectrometer and/or a pulse-height analyzer is provided within the apparatus for recovery of the information from the light beam to determine a size, shape, identification or other characteristics about the cells or particles being analyzed. The recovered information can be grouped in a multi-dimensional coordinate space for identification of particular types of cells or particles. In some embodiments of the apparatus, the resonant optical cavity can be formed, at least in part, from a vertical-cavity surface-emitting laser. The apparatus and method are particularly suited to the analysis of biological cells, including blood cells, and can further include processing means for manipulating, sorting, or eradicating cells after analysis thereof.

Inelastic deformation demands of regular steel frames subjected to pulse-like near-fault ground shakings

NASA Astrophysics Data System (ADS)

Siahpolo, Navid; Gerami, Mohsen; Vahdani, Reza

2016-09-01

Evaluating the capability of elastic Load Patterns (LPs) including seismic codes and modified LPs such as Method of Modal Combination (MMC) and Upper Bound Pushover Analysis (UBPA) in estimating inelastic demands of non deteriorating steel moment frames is the main objective of this study. The Static Nonlinear Procedure (NSP) is implemented and the results of NSP are compared with Nonlinear Time History Analysis (NTHA). The focus is on the effects of near-fault pulselike ground motions. The primary demands of interest are the maximum floor displacement, the maximum story drift angle over the height, the maximum global ductility, the maximum inter-story ductility and the capacity curves. Five types of LPs are selected and the inelastic demands are calculated under four levels of inter-story target ductility ( μ t) using OpenSees software. The results show that the increase in μ t coincides with the migration of the peak demands over the height from the top to the bottom stories. Therefore, all LPs estimate the story lateral displacement accurately at the lower stories. The results are almost independent of the number of stories. While, the inter-story drift angle (IDR) obtained from MMC method has the most appropriate accuracy among the other LPs. Although, the accuracy of this method decreases with increasing μ t so that with increasing number of stories, IDR is smaller or greater than the values resulted from NTHA depending on the position of captured results. In addition, increasing μ t decreases the accuracy of all LPs in determination of critical story position. In this case, the MMC method has the best coincidence with distribution of inter-story ductility over the height.

Pulse-height loss in the signal readout circuit of compound semiconductor detectors

NASA Astrophysics Data System (ADS)

Nakhostin, M.; Hitomi, K.

2018-06-01

Compound semiconductor detectors such as CdTe, CdZnTe, HgI2 and TlBr are known to exhibit large variations in their charge collection times. This paper considers the effect of such variations on the measurement of induced charge pulses by using resistive feedback charge-sensitive preamplifiers. It is shown that, due to the finite decay-time constant of the preamplifiers, the capacitive decay during the signal readout leads to a variable deficit in the measurement of ballistic signals and a digital pulse processing method is employed to correct for it. The method is experimentally examined by using sampled pulses from a TlBr detector coupled to a charge-sensitive preamplifier with 150 μs of decay-time constant and 20 % improvement in the energy resolution of the detector at 662 keV is achieved. The implications of the capacitive decay on the correction of charge-trapping effect by using depth-sensing technique are also considered.

GEOS-C altimeter attitude bias error correction. [gate-tracking radar

NASA Technical Reports Server (NTRS)

Marini, J. W.

1974-01-01

A pulse-limited split-gate-tracking radar altimeter was flown on Skylab and will be used aboard GEOS-C. If such an altimeter were to employ a hypothetical isotropic antenna, the altimeter output would be independent of spacecraft orientation. To reduce power requirements the gain of the altimeter antenna proposed is increased to the point where its beamwidth is only a few degrees. The gain of the antenna consequently varies somewhat over the pulse-limited illuminated region of the ocean below the altimeter, and the altimeter output varies with antenna orientation. The error introduced into the altimeter data is modeled empirically, but close agreements with the expected errors was not realized. The attitude error effects expected with the GEOS-C altimeter are modelled using a form suggested by an analytical derivation. The treatment is restricted to the case of a relatively smooth sea, where the height of the ocean waves are small relative to the spatial length (pulse duration times speed of light) of the transmitted pulse.

Miniaturized pulsed CO2 laser with sealed electron source

NASA Astrophysics Data System (ADS)

Bychkov, Y. I.; Orlovskiy, V. M.; Osipov, V. V.; Poteryayev, A. G.

1984-04-01

A new miniature electron beam-controlled CO2 laser (the MIG-3) contains an electron accelerator, gas cell and DC supply in one large unit (0.22 x 0,16 x 0.7 m) and the accelerator power supply and laser control panel in a second smaller unit. The overall weight of the instrument in 30 kg. The electron beam is controlled by four vacuum diodes in parallel; a 180 KV pulse is fed to the vacuum diode inputs from a "NORA" series-produced X-ray source (the MIRA-3D) also is used). The total electron beam current from all diodes was 600 A following the foil with a half-height width of 10 ns. The lasing medium is CO2:N2 - 1:1 at 4.5 atm. The maximum stimulated emission pulse energy was 1 J with an efficiency of 8% when the pressure was 4 atm. With a pulse repetition rate of 4 Hz, the average power consumption of the unit was 100 W.

Ground-echo characteristics for a ground-target pulse-Doppler radar fuze of high duty ratio

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

Williams, C.S.

1973-11-21

From Tri-service electronic fuse symposium; Washington, District of Columbia, USA (26 Nov 1973). A pulse-Doppler radar fuze for use against ground targets at high burst heights can operate at low peak power provided a high duty ratio is used. The high duty ratio brings about ambiguous ground return that is prevented from firing the fuze by randomly coding the phase of the transmitted pulses. This causes the ambiguous return to appear as random noise. This paper provides formulas for the calculation of the clutter-noise power density and of the signal power so that the performance of the radar can bemore » determined. The paper also discusses the myth of decorrelation'' that is alleged to destroy the transmittedphase modulation in the echo and so make it useless. (auth)« less

Biased-probe-induced water ion injection into amorphous polymers investigated by electric force microscopy

NASA Astrophysics Data System (ADS)

Knorr, Nikolaus; Rosselli, Silvia; Miteva, Tzenka; Nelles, Gabriele

2009-06-01

Although charging of insulators by atomic force microscopy (AFM) has found widespread interest, often with data storage or nanoxerography in mind, less attention has been paid to the charging mechanism and the nature of the charge. Here we present a systematic study on charging of amorphous polymer films by voltage pulses applied to conducting AFM probes. We find a quadratic space charge limited current law of Kelvin probe force microscopy and electrostatic force microscopy peak volumes in pulse height, offset by a threshold voltage, and a power law in pulse width of positive exponents smaller than one. We interpret the results by a charging mechanism of injection and surface near accumulation of aqueous ions stemming from field induced water adsorption, with threshold voltages linked to the water affinities of the polymers.

Effect of a Near Fault on the Seismic Response of a Base-Isolated Structure with a Soft Storey

NASA Astrophysics Data System (ADS)

Athamnia, B.; Ounis, A.; Abdeddaim, M.

2017-12-01

This study focuses on the soft-storey behavior of RC structures with lead core rubber bearing (LRB) isolation systems under near and far-fault motions. Under near-fault ground motions, seismic isolation devices might perform poorly because of large isolator displacements caused by large velocity and displacement pulses associated with such strong motions. In this study, four different structural models have been designed to study the effect of soft-storey behavior under near-fault and far-fault motions. The seismic analysis for isolated reinforced concrete buildings is carried out using a nonlinear time history analysis method. Inter-story drifts, absolute acceleration, displacement, base shear forces, hysteretic loops and the distribution of plastic hinges are examined as a result of the analysis. These results show that the performance of a base isolated RC structure is more affected by increasing the height of a story under nearfault motion than under far-fault motion.

Aluminum Surface Texturing by Means of Laser Interference Metallurgy

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

Chen, Jian; Sabau, Adrian S; Jones, Jonaaron F.

2015-01-01

The increasing use of lightweight materials, such as aluminum alloys, in auto body structures requires more effective surface cleaning and texturing techniques to improve the quality of the structural components. The present work introduces a novel surface treatment method using laser interferometry produced by two beams of a pulsed Nd:YAG laser operating at 10Hz of frequency to clean aluminum surfaces, and meanwhile creating periodic and rough surface structures. The influences of beam size, laser fluence, wavelength, and pulse number per spot are investigated. High resolution optical profiler images reveal the change of the peak-to-valley height on the laser-treated surface.

The UHURU X-ray instrument.

NASA Technical Reports Server (NTRS)

Jagoda, N.; Austin, G.; Mickiewicz, S.; Goddard, R.

1972-01-01

On Dec. 12, 1970, the UHURU X-ray observatory was launched into equatorial orbit with the prime mission of conducting an all-sky survey of astronomical X-ray sources with intensities of 0.00005 Sco-X1 or greater. The X-ray detection system contains 12 gas-filled proportional counters, 6 behind each collimator. The aspect system is discussed together with the structure, the pulse height analyzer, the command system, the calibration system, and the power distribution system. Pulse shape discrimination circuits used on UHURU use the same technique that was used on the system originally developed for large area proportional counters described by Gorenstein and Mickiewicz (1968).

Changes in optical properties of electroporated cells as revealed by digital holographic microscopy

PubMed Central

Calin, Violeta L.; Mihailescu, Mona; Mihale, Nicolae; Baluta, Alexandra V.; Kovacs, Eugenia; Savopol, Tudor; Moisescu, Mihaela G.

2017-01-01

Changes in optical and shape-related characteristics of B16F10 cells after electroporation were investigated using digital holographic microscopy (DHM). Bipolar rectangular pulses specific for electrochemotherapy were used. Electroporation was performed in an “off-axis” DHM set-up without using exogenous markers. Two types of cell parameters were monitored seconds and minutes after pulse train application: parameters addressing a specifically defined area of the cell (refractive index and cell height) and global cell parameters (projected area, optical phase shift profile and dry mass). The biphasic behavior of cellular parameters was explained by water and mannitol dynamics through the electropermeabilized cell membrane. PMID:28736667

Treatment of hypertrophic scars and keloids using intense pulsed light (IPL).

PubMed

Erol, O Onur; Gurlek, Ali; Agaoglu, Galip; Topcuoglu, Ela; Oz, Hayat

2008-11-01

Keloids and hypertrophic scars are extremely disturbing to patients, both physically and psychologically. This study prospectively assessed the safety and efficacy of intense pulsed light (IPL) on scars originating from burns, trauma, surgery, and acne. Hypertrophic scars in 109 patients, originating from surgical incisions (n = 55), traumatic cuts (traffic accidents) (n = 24), acne scars (n = 6), keloids (n = 5), and burns (n = 19), were treated using an IPL Quantum device. Treatment was administered at 2-4-week intervals, and patients received an average of 8 treatments (range = 6-24). Using digital photographs, Changes in scar appearance were assessed by two physicians who were blinded to the study patients and treatments. The photographs were graded on a scale of 0 to 4 (none, minimal, moderate, good, excellent) for improvement in overall clinical appearance and reduction in height, erythema, and hardness. An overall clinical improvement in the appearance of scars and reductions in height, erythema, and hardness were seen in the majority of the patients (92.5%). Improvement was excellent in 31.2% of the patients, good in 25.7%, moderate in 34%, and minimal in 9.1%. Over half the patients had good or excellent improvement. In the preventive IPL treatment group, 65% had good to excellent improvement in clinical appearance. Patient satisfaction was very high. This study suggests that IPL is effective not only in improving the appearance of hypertrophic scars and keloids regardless of their origin, but also in reducing the height, redness, and hardness of scars.

Modeling the performance of a photon counting x-ray detector for CT: Energy response and pulse pileup effects

PubMed Central

Taguchi, Katsuyuki; Zhang, Mengxi; Frey, Eric C.; Wang, Xiaolan; Iwanczyk, Jan S.; Nygard, Einar; Hartsough, Neal E.; Tsui, Benjamin M. W.; Barber, William C.

2011-01-01

Purpose: Recently, photon counting x-ray detectors (PCXDs) with energy discrimination capabilities have been developed for potential use in clinical computed tomography (CT) scanners. These PCXDs have great potential to improve the quality of CT images due to the absence of electronic noise and weights applied to the counts and the additional spectral information. With high count rates encountered in clinical CT, however, coincident photons are recorded as one event with a higher or lower energy due to the finite speed of the PCXD. This phenomenon is called a “pulse pileup event” and results in both a loss of counts (called “deadtime losses”) and distortion of the recorded energy spectrum. Even though the performance of PCXDs is being improved, it is essential to develop algorithmic methods based on accurate models of the properties of detectors to compensate for these effects. To date, only one PCXD (model DXMCT-1, DxRay, Inc., Northridge, CA) has been used for clinical CT studies. The aim of that study was to evaluate the agreement between data measured by DXMCT-1 and those predicted by analytical models for the energy response, the deadtime losses, and the distorted recorded spectrum caused by pulse pileup effects. Methods: An energy calibration was performed using 99mTc (140 keV), 57Co (122 keV), and an x-ray beam obtained with four x-ray tube voltages (35, 50, 65, and 80 kVp). The DXMCT-1 was placed 150 mm from the x-ray focal spot; the count rates and the spectra were recorded at various tube current values from 10 to 500 μA for a tube voltage of 80 kVp. Using these measurements, for each pulse height comparator we estimated three parameters describing the photon energy-pulse height curve, the detector deadtime τ, a coefficient k that relates the x-ray tube current I to an incident count rate a by a=k×I, and the incident spectrum. The mean pulse shape of all comparators was acquired in a separate study and was used in the model to estimate the distorted recorded spectrum. The agreement between data measured by the DXMCT-1 and those predicted by the models was quantified by the coefficient of variation (COV), i.e., the root mean square difference divided by the mean of the measurement. Results: Photon energy versus pulse height curves calculated with an analytical model and those measured using the DXMCT-1 were in agreement within 0.2% in terms of the COV. The COV between the output count rates measured and those predicted by analytical models was 2.5% for deadtime losses of up to 60%. The COVs between spectra measured and those predicted by the detector model were within 3.7%–7.2% with deadtime losses of 19%–46%. Conclusions: It has been demonstrated that the performance of the DXMCT-1 agreed exceptionally well with the analytical models regarding the energy response, the count rate, and the recorded spectrum with pulse pileup effects. These models will be useful in developing methods to compensate for these effects in PCXD-based clinical CT systems. PMID:21452746

Space charge deposition in tubular channel ferroelectrets: A combined fluorescence imaging/LIMM study with finite element analysis

NASA Astrophysics Data System (ADS)

Nepal, Neerajan; Altafim, Ruy Alberto Pisani; Mellinger, Axel

2017-06-01

Ferroelectrets, i.e., soft materials with electric charges deposited on the surfaces of internal voids, are well known for their potential in transducer applications and energy harvesting. Due to their regular geometry and optical transparency, tubular channel ferroelectrets (manufactured by laminating polymer films around a polytetrafluoroethylene template which is later removed) are well-suited for studying the process of charge deposition. Understanding how space charges are formed on the internal surfaces will lead to improvements in the charge density and in the piezoelectric performance of these films. In this work, the inception voltage for dielectric barrier discharges (and hence the onset of charge deposition) was measured using two independent techniques, fluorescence imaging and the laser intensity modulation method (LIMM). The results (around 1.4-1.7 kV, depending on the void height) are in agreement within ±50 V. The internal electric field distribution was calculated using finite element analysis (FEA). Combined with Paschen's law, these calculations explained the experimentally observed discharge patterns, starting from the channel edges in thick samples, but glowing more uniformly in films with void heights of 50 μm or less. A time-dependent FEA simulation of the LIMM measurement reproduced the observed thermoelastic resonances and their effect on the LIMM signal, and explained its seemingly erratic behavior. This approach has great potential for analyzing LIMM and thermal pulse data obtained in inhomogeneous materials.

High Temperature Monitoring the Height of Condensed Water in Steam Pipes

NASA Technical Reports Server (NTRS)

Bar-Cohen, Yoseph; Lih, Shyh-Shiuh; Badescu, Mircea; Bao, Xiaoqi; Sherrit, Stewart; Widholm, Scott; Ostlund, Patrick; Blosiu, Julian

2011-01-01

An in-service health monitoring system is needed for steam pipes to track through their wall the condensation of water. The system is required to measure the height of the condensed water inside the pipe while operating at temperatures that are as high as 250 deg. C. The system needs to be able to make real time measurements while accounting for the effects of cavitation and wavy water surface. For this purpose, ultrasonic wave in pulse-echo configuration was used and reflected signals were acquired and auto-correlated to remove noise from the data and determine the water height. Transmitting and receiving the waves is done by piezoelectric transducers having Curie temperature that is significantly higher than 250 deg. C. Measurements were made at temperatures as high as 250 deg. C and have shown the feasibility of the test method. This manuscript reports the results of this feasibility study.

A cohort evaluation on arterial stiffness and hypertensive disorders in pregnancy.

PubMed

Lim, Wai Yee; Saw, Seang Mei; Tan, Kok Hian; Yeo, George S H; Kwek, Kenneth Y C

2012-12-26

Hypertensive disorders in pregnancy are associated with systemic endothelial dysfunction leading to impaired physiological vasodilation. Recent evidence has shown central aortic pressures obtained through pulse wave analysis, at less than 14 weeks of gestation, to be predictive of pre-eclampsia. In light of this, we aimed to evaluate the role of central aortic stiffness in the prediction and discrimination of hypertensive disorders in pregnancy. A cohort study of women with viable, singleton pregnancies at less than 14 weeks of amenorrhoea, and without multiple pregnancies, autoimmune or renal disease, diagnosed with aneuploidy or fetal anomaly will be recruited from a single maternity hospital and followed up till delivery and puerperium. A targeted sample size of 1000 eligible pregnant women will be enrolled into the study from antenatal clinics. Main exposure under study is central aortic pulse pressure using radial pulse wave recording, and the outcomes under follow-up are gestational hypertension and pre-eclampsia. Other measures include lifestyle factors such as smoking, physical exercise, psychometric evaluations, vasoactive factors, uterine artery pulsatility index, height and weight measurements. These measures will be repeated over 4 antenatal visits at 11-14, 18-22, 28-32 and above 34 weeks of gestation. Double data entry will be performed on Microsoft Access, and analysis of data will include the use of random effect models and receiver operating characteristic curves on Stata 11.2. The proposed study design will enable a longitudinal evaluation of the central aortic pressure changes as a marker for vascular compliance during pregnancy. As measures are repeated over time, the timing and severity of changes are detectable, and findings may yield important information on how aberrant vascular responses occur and its role in the early detection and prediction of hypertensive disorders.

Gold nanoparticles on the surface of soda-lime glass: morphological, linear and nonlinear optical characterization.

PubMed

Romani, E C; Vitoreti, Douglas; Gouvêa, Paula M P; Caldas, P G; Prioli, R; Paciornik, S; Fokine, Michael; Braga, Arthur M B; Gomes, Anderson S L; Carvalho, Isabel C S

2012-02-27

Materials presenting high optical nonlinearity, such as materials containing metal nanoparticles (NPs), can be used in various applications in photonics. This motivated the research presented in this paper, where morphological, linear and nonlinear optical characteristics of gold NPs on the surface of bulk soda-lime glass substrates were investigated as a function of nanoparticle height. The NPs were obtained by annealing gold (Au) thin films previously deposited on the substrates. Pixel intensity histogram fitting on Atomic Force Microscopy (AFM) images was performed to obtain the thickness of the deposited film. Image analysis was employed to obtain the statistical distribution of the average height of the NPs. In addition, absorbance spectra of the samples before and after annealing were measured. Finally, the nonlinear refractive index (n2) and the nonlinear absorption index (α2) at 800 nm were obtained before and after annealing by using the thermally managed eclipse Z-scan (TM-EZ) technique with a Ti:Sapphire laser (150 fs pulses). Results show that both n2 and α2 at this wavelength change signs after the annealing and that the samples presented a high nonlinear refractive index.

Survey of the Effects of Exposure to 900 MHz Radiofrequency Radiation Emitted by a GSM Mobile Phone on the Pattern of Muscle Contractions in an Animal Model

PubMed Central

Mortazavi, S. M. J.; Rahimi, S.; Talebi, A.; Soleimani, A.; Rafati, A.

2015-01-01

Background: The rapid development of wireless telecommunication technologies over the past decades, has led to significant changes in the exposure of the general public to electromagnetic fields. Nowadays, people are continuously exposed to different sources of electromagnetic fields such as mobile phones, mobile base stations, cordless phones, Wi-Fi routers, and power lines. Therefore, the last decade witnessed a rapidly growing concern about the possible health effects of exposure to electromagnetic fields emitted by these sources. Materials and Methods: In this study that was aimed at investigating the effects of exposure to radiofrequency (RF) radiation emitted by a GSM mobile phone on the pattern of contraction in frog’s isolated gastrocnemius muscle after stimulation with single square pulses of 1V (1 Hz), pulse height of contractions, the time interval between two subsequent contractions and the latency period were measured. Results: Our findings showed that the pulse height of contractions muscle could be affected by the exposure to electromagnetic fields. Especially, the latency period was effectively altered in RF-exposed samples. However, none of the experiments could show an alteration in the time interval between two subsequent contractions after exposure to electromagnetic fields. Conclusion: These findings support early reports which indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians including the effects on the pattern of muscle extractions. PMID:26396968

K-edge energy-based calibration method for photon counting detectors

NASA Astrophysics Data System (ADS)

Ge, Yongshuai; Ji, Xu; Zhang, Ran; Li, Ke; Chen, Guang-Hong

2018-01-01

In recent years, potential applications of energy-resolved photon counting detectors (PCDs) in the x-ray medical imaging field have been actively investigated. Unlike conventional x-ray energy integration detectors, PCDs count the number of incident x-ray photons within certain energy windows. For PCDs, the interactions between x-ray photons and photoconductor generate electronic voltage pulse signals. The pulse height of each signal is proportional to the energy of the incident photons. By comparing the pulse height with the preset energy threshold values, x-ray photons with specific energies are recorded and sorted into different energy bins. To quantitatively understand the meaning of the energy threshold values, and thus to assign an absolute energy value to each energy bin, energy calibration is needed to establish the quantitative relationship between the threshold values and the corresponding effective photon energies. In practice, the energy calibration is not always easy, due to the lack of well-calibrated energy references for the working energy range of the PCDs. In this paper, a new method was developed to use the precise knowledge of the characteristic K-edge energy of materials to perform energy calibration. The proposed method was demonstrated using experimental data acquired from three K-edge materials (viz., iodine, gadolinium, and gold) on two different PCDs (Hydra and Flite, XCounter, Sweden). Finally, the proposed energy calibration method was further validated using a radioactive isotope (Am-241) with a known decay energy spectrum.

Ultrasound analysis of mental artery flow in elderly patients: a case-control study.

PubMed

Baladi, Marina G; Tucunduva Neto, Raul R C M; Cortes, Arthur R G; Aoki, Eduardo M; Arita, Emiko S; Freitas, Claudio F

2015-01-01

Mental artery flow decreases with age and may have an aetiological role in alveolar ridge atrophy. The aim of this study was to identify factors associated with alterations of mental artery flow, assessed by ultrasonography. This case-control study was conducted on elderly patients (aged above 60 years) at the beginning of dental treatment. Intraoral B-mode Doppler ultrasonography was used to assess mental artery flow. The cases were defined as patients with a weak/absent ultrasound signal, whereas the controls presented a strong ultrasound signal. Demographics and radiographic findings (low bone mineral density on dual-energy X-ray absorptiometry and mandibular cortical index on panoramic radiographs) were analysed as risk factors for weak/absent ultrasound signal and were calculated as adjusted odds ratios (AORs) with 95% confidence intervals (CIs) using conditional logistic regression. In addition, the Student's t-test was used to compare the mean alveolar bone height of the analysed groups. A p-value <0.05 was considered statistically significant. A total of 30 ultrasound examinations (12 cases and 18 controls) were analysed. A weak/absent mental artery pulse strength was significantly associated with edentulism (AOR = 3.67; 95% CI = 0.86-15.63; p = 0.046). In addition, there was a significant difference in alveolar bone height between edentulous cases and controls (p = 0.036). Within the limitations of this study, the present results indicate that edentulism is associated with diminished mental artery flow, which, in turn, affects alveolar bone height.

Neutron spectroscopy for pulsed beams with frame overlap using a double time-of-flight technique

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

Harrig, K. P.; Goldblum, B. L.; Brown, J. A.

A new double time-of- ight (dTOF) neutron spectroscopy technique has been developed for pulsed broad spectrum sources with a duty cycle that results in frame overlap, where fast neutrons from a given pulse overtake slower neutrons from previous pulses. Using a tunable beam at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory, neutrons were produced via thick-target breakup of 16 MeV deuterons on a beryllium target in the cyclotron vault. The breakup spectral shape was deduced from a dTOF measurement using an array of EJ-309 organic liquid scintillators. Simulation of the neutron detection efficiency of the scintillator array was performedmore » using both GEANT4 and MCNP6. The efficiency- corrected spectral shape was normalized using a foil activation technique to obtain the energy-dependent flux of the neutron beam at zero degrees with respect to the incoming deuteron beam. The dTOF neutron spectrum was compared to spectra obtained using HEPROW and GRAVEL pulse height spectrum unfolding techniques. While the unfolding and dTOF results exhibit some discrepancies in shape, the integrated flux values agree within two standard deviations. As a result, this method obviates neutron time-of-flight spectroscopy challenges posed by pulsed beams« less

X-Ray Pulse Selector With 2 ns Lock-in Phase Setting And Stability

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

Lindenau, B.; Raebiger, J.; Polachowski, S.

2004-05-12

Selector devices, which are based on magnetically suspended, high speed triangular shutter rotors, have been designed and built in cooperation with ESRF, APS, and recently Spring-8 for time resolved studies with isolated x-ray pulses at white beam lines. The x-ray pulse selection is accomplished by means of a beam channel along one of the edges of the triangular rotor, which opens once per revolution. Entrance and exit apertures of the channel can be designed wedge shaped for variable tuning of the channel height between 0.1 mm to 0.9 mm. At the 1 kHz maximum operation frequency of a 220 mmmore » diameter disk with 190 mm channel length, the practicable open times of the channel are demonstrated to range down to 200 ns. The selector drive electronics is directly coupled to the storage ring RF clock for rotational phase control. It allows for continuous selector operation in phase locked mode to the temporal pulse structure of the synchrotron at 2 ns RMS stability. The phase angle between the pulse transmission period and the synchrotron bunch sequence can be adjusted with similar precision for X-ray pulse selection according to the experimental needs. ID09, Michael Wulff ; BioCARS 14-BM, Reinhard Pahl; BL40-XU, Shin-ichi Adachi.« less

Neutron spectroscopy for pulsed beams with frame overlap using a double time-of-flight technique

DOE PAGES

Harrig, K. P.; Goldblum, B. L.; Brown, J. A.; ...

2017-10-16

A new double time-of- ight (dTOF) neutron spectroscopy technique has been developed for pulsed broad spectrum sources with a duty cycle that results in frame overlap, where fast neutrons from a given pulse overtake slower neutrons from previous pulses. Using a tunable beam at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory, neutrons were produced via thick-target breakup of 16 MeV deuterons on a beryllium target in the cyclotron vault. The breakup spectral shape was deduced from a dTOF measurement using an array of EJ-309 organic liquid scintillators. Simulation of the neutron detection efficiency of the scintillator array was performedmore » using both GEANT4 and MCNP6. The efficiency- corrected spectral shape was normalized using a foil activation technique to obtain the energy-dependent flux of the neutron beam at zero degrees with respect to the incoming deuteron beam. The dTOF neutron spectrum was compared to spectra obtained using HEPROW and GRAVEL pulse height spectrum unfolding techniques. While the unfolding and dTOF results exhibit some discrepancies in shape, the integrated flux values agree within two standard deviations. As a result, this method obviates neutron time-of-flight spectroscopy challenges posed by pulsed beams« less

Interaction with the lower ionosphere of electromagnetic pulses from lightning - Heating, attachment, and ionization

NASA Technical Reports Server (NTRS)

Taranenko, Y. N.; Inan, U. S.; Bell, T. F.

1993-01-01

A Boltzmann formulation of the electron distribution function and Maxwell's equations for the EM fields are used to simulate the interaction of lightning radiated EM pulses with the lower ionosphere. Ionization and dissociative attachment induced by the heated electrons cause significant changes in the local electron density, N(e). Due to 'slow' field changes of typical lightning EM pulses over time scales of tens of microsec, the distribution function follows the quasi-equilibrium solution of the Boltzmann equation in the altitude range of interest (70 to 100 km). The EM pulse is simulated as a planar 100 microsec long single period oscillation of a 10 kHz wave injected at 70 km. Under nighttime conditions, individual pulses of intensity 10-20 V/m (normalized to 100 km horizontal distance) produce changes in N(e) of 1-30 percent while a sequence of pulses leads to strong modification of N(e) at altitudes less than 95 km. The N(e) changes produce a 'sharpening' of the lower ionospheric boundary by causing a reduction in electron density at 75-85 km (due to attachment) and a substantial increase at 85-95 km (due to ionization) (e.g., the scale height decreases by a factor of about 2 at about 85 km for a single 20 V/m EM pulse). No substantial N(e) changes occur during daytime.

Measuring and Validating Neutron Capture Cross Sections Using a Lead Slowing-Down Spectrometer

NASA Astrophysics Data System (ADS)

Thompson, Nicholas

Accurate nuclear data is essential for the modeling, design, and operation of nuclear systems. In this work, the Rensselaer Polytechnic Institute (RPI) Lead Slowing-Down Spectrometer (LSDS) at the Gaerttner Linear Accelerator Center (LINAC) was used to measure neutron capture cross sections and validate capture cross sections in cross section libraries. The RPI LINAC was used to create a fast burst of neutrons in the center of the LSDS, a large cube of high purity lead. A sample and YAP:Ce scintillator were placed in the LSDS, and as neutrons lost energy through scattering interactions with the lead, the scintillator detected capture gammas resulting from neutron capture events in the sample. Samples of silver, gold, cobalt, iron, indium, molybdenum, niobium, nickel, tin, tantalum, and zirconium were measured. Data was collected as a function of time after neutron pulse, or slowing-down time, which is correlated to average neutron energy. An analog and a digital data acquisition system collected data simultaneously, allowing for collection of pulse shape information as well as timing. Collection of digital data allowed for pulse shape analysis after the experiment. This data was then analyzed and compared to Monte Carlo simulations to validate the accuracy of neutron capture cross section libraries. These measurements represent the first time that neutron capture cross sections have been measured using an LSDS in the United States, and the first time tools such as coincidence measurements and pulse height weighting have been applied to measurements of neutron capture cross sections using an LSDS. Significant differences between measurement results and simulation results were found in multiple materials, and some errors in nuclear data libraries have already been identified due to these measurements.

Variability of the Mixed-Layer Height Over Mexico City

NASA Astrophysics Data System (ADS)

García-Franco, J. L.; Stremme, W.; Bezanilla, A.; Ruiz-Angulo, A.; Grutter, M.

2018-02-01

The diurnal and seasonal variability of the mixed-layer height in urban areas has implications for ground-level air pollution and the meteorological conditions. Measurements of the backscatter of light pulses with a commercial lidar system were performed for a continuous period of almost six years between 2011 and 2016 in the southern part of Mexico City. The profiles were temporally and vertically smoothed, clouds were filtered out, and the mixed-layer height was determined with an ad hoc treatment of both the filtered and unfiltered profiles. The results are in agreement when compared with values of mixed-layer height reconstructed from, (i) radiosonde data, and (ii) surface and vertical column densities of a trace gas. The daily maxima of the mean mixed-layer height reach values > 3 km above ground level in the months of March-April, and are clearly lower (< 2.7 km ) during the colder months from September-December. Mean daily minima are typically observed at 0700 local time (UTC - 6h), and are lowest during the winter months with values on average below 500 m. The data presented here show an anti-correlation between high-pollution episodes and the height of the mixed layer. The growth rate of the convective mixed-layer height has a seasonal behaviour, which is characterized together with the mixed-layer-height anomalies. A clear residual layer is evident from the backscattered signals recorded in days with specific atmospheric conditions, but also from the cloud-filtered mean diurnal profiles. The occasional presence of a residual layer results in an overestimation of the reported mixed-layer height during the night and early morning hours.

Variability of the Mixed-Layer Height Over Mexico City

NASA Astrophysics Data System (ADS)

García-Franco, J. L.; Stremme, W.; Bezanilla, A.; Ruiz-Angulo, A.; Grutter, M.

2018-06-01

The diurnal and seasonal variability of the mixed-layer height in urban areas has implications for ground-level air pollution and the meteorological conditions. Measurements of the backscatter of light pulses with a commercial lidar system were performed for a continuous period of almost six years between 2011 and 2016 in the southern part of Mexico City. The profiles were temporally and vertically smoothed, clouds were filtered out, and the mixed-layer height was determined with an ad hoc treatment of both the filtered and unfiltered profiles. The results are in agreement when compared with values of mixed-layer height reconstructed from, (i) radiosonde data, and (ii) surface and vertical column densities of a trace gas. The daily maxima of the mean mixed-layer height reach values > 3 km above ground level in the months of March-April, and are clearly lower (< 2.7 km) during the colder months from September-December. Mean daily minima are typically observed at 0700 local time (UTC - 6h), and are lowest during the winter months with values on average below 500 m. The data presented here show an anti-correlation between high-pollution episodes and the height of the mixed layer. The growth rate of the convective mixed-layer height has a seasonal behaviour, which is characterized together with the mixed-layer-height anomalies. A clear residual layer is evident from the backscattered signals recorded in days with specific atmospheric conditions, but also from the cloud-filtered mean diurnal profiles. The occasional presence of a residual layer results in an overestimation of the reported mixed-layer height during the night and early morning hours.

Direct measurement of mammographic X-ray spectra with a digital CdTe detection system.

PubMed

Abbene, Leonardo; Gerardi, Gaetano; Principato, Fabio; Del Sordo, Stefano; Raso, Giuseppe

2012-01-01

In this work we present a detection system, based on a CdTe detector and an innovative digital pulse processing (DPP) system, for high-rate X-ray spectroscopy in mammography (1-30 keV). The DPP system performs a height and shape analysis of the detector pulses, sampled and digitized by a 14-bit, 100 MHz ADC. We show the results of the characterization of the detection system both at low and high photon counting rates by using monoenergetic X-ray sources and a nonclinical X-ray tube. The detection system exhibits excellent performance up to 830 kcps with an energy resolution of 4.5% FWHM at 22.1 keV. Direct measurements of clinical molybdenum X-ray spectra were carried out by using a pinhole collimator and a custom alignment device. A comparison with the attenuation curves and the half value layer values, obtained from the measured and simulated spectra, from an ionization chamber and from a solid state dosimeter, also shows the accuracy of the measurements. These results make the proposed detection system a very attractive tool for both laboratory research, calibration of dosimeters and advanced quality controls in mammography.

Electrochemical Study of Carbon Nanotubes/Nanohybrids for Determination of Metal Species Cu2+ and Pb2+ in Water Samples

PubMed Central

Oliveira Silva, Andréa Claudia; de Oliveira, Luis Carlos Ferreira; Vieira Delfino, Angladis; Meneghetti, Mario Roberto

2016-01-01

The use of nanomaterials, such as nanoparticles and nanotubes, for electrochemical detection of metal species has been investigated as a way of modifying electrodes by electrochemical stripping analysis. The present study develops a new methodology based on a comparative study of nanoparticles and nanotubes with differential pulse anodic stripping voltammetry (DPASV) and examines the simultaneous determination of copper and lead. The glassy carbon electrode modified by gold nanoparticles demonstrated increased sensitivity and decreased detection limits, among other improvements in analytical performance data. Under optimized conditions (deposition potential −0.8 V versus Ag/AgCl; deposition time, 300 s; resting time, 10 s; pulse amplitude, 50 mV; and voltage step height, 4 mV), the detection limits were 0.2279 and 0.3321 ppb, respectively, for determination of Pb2+ and Cu2+. The effects of cations and anions on the simultaneous determination of metal ions do not exhibit significant interference, thereby demonstrating the selectivity of the electrode for simultaneous determination of Pb2+ and Cu2+. The same method was also used to determine Cu2+ in water samples. PMID:27882263

Characterization of the high-energy neutron beam of the PRISMA beamline using a diamond detector

NASA Astrophysics Data System (ADS)

Cazzaniga, C.; Frost, C. D.; Minniti, T.; Schooneveld, E.; Perelli Cippo, E.; Tardocchi, M.; Rebai, M.; Gorini, G.

2016-07-01

The high-energy neutron component (En > 10 MeV) of the neutron spectrum of PRISMA, a beam-line at the ISIS spallation source, has been characterized for the first time. Neutron measurements using a Single-crystal Diamond Detector at a short-pulse source are obtained by a combination of pulse height and time of flight analysis. An XY scan provides a 2D map of the high-energy neutron beam which has a diameter of about 40 mm. The high neutron flux, that has been found to be (3.8 ± 0.7) · 105 cm-2s-1 for En > 10 MeV in the centre, opens up for a possible application of the beam-line as a high-energy neutron irradiation position. Results are of interest for the development of the ChipIR beam-line, which will feature an atmospheric-like neutron spectrum for chip irradiation experiment. Furthermore, these results demonstrate that diamond detectors can be used at spallation sources to investigate the transport of high-energy neutrons down instruments which is of interest in general to designers as high-energy neutrons are a source of background in thermal beamlines.

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

NASA Astrophysics Data System (ADS)

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

2016-08-01

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

An integrated radiation physics computer code system.

NASA Technical Reports Server (NTRS)

Steyn, J. J.; Harris, D. W.

1972-01-01

An integrated computer code system for the semi-automatic and rapid analysis of experimental and analytic problems in gamma photon and fast neutron radiation physics is presented. Such problems as the design of optimum radiation shields and radioisotope power source configurations may be studied. The system codes allow for the unfolding of complex neutron and gamma photon experimental spectra. Monte Carlo and analytic techniques are used for the theoretical prediction of radiation transport. The system includes a multichannel pulse-height analyzer scintillation and semiconductor spectrometer coupled to an on-line digital computer with appropriate peripheral equipment. The system is geometry generalized as well as self-contained with respect to material nuclear cross sections and the determination of the spectrometer response functions. Input data may be either analytic or experimental.

The University of Chicago cosmic ray electrons and nuclei experiment on the H spacecraft

NASA Technical Reports Server (NTRS)

Meyer, P.; Evenson, P.

1978-01-01

The University of Chicago instrument on the Heliocentric spacecraft (MEH experiment) will measure the energy spectrum of cosmic electrons in the range 5-400 MeV. In addition, the energy spectra and relative abundances of nuclei from protons to the iron group, with energies ranging from 30 MeV/n to 15 GeV/n, will be determined. Primary scientific objectives involve the study of the long and short term variability of these components as a probe of the structure of the heliosphere. Particles are identified by multiparameter analysis using the pulse height analyzed signals from eight active detectors - silicon solid state, plastic and crystal scintillators are solid and gas Cerenkov counters. Data return is optimized by a three level priority logic scheme.

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

Divani, Nazila, E-mail: n-divani@birjand.ac.ir; Firoozabadi, Mohammad M.; Bayat, Esmail

Scintillators are almost used in any nuclear laboratory. These detectors combine of scintillation materials, PMT and a voltage divider. Voltage dividers are different in resistive ladder design. But the effect of decoupling capacitors and damping resistors haven’t discussed yet. In this paper at first a good equilibrium circuit designed for PMT, and it was used for investigating about capacitors and resistors in much manner. Results show that decoupling capacitors have great effect on PMT output pulses. In this research, it was tried to investigate the effect of Capacitor’s value and places on PMT voltage divider in Neutron-Gamma discrimination capability. Therefore,more » the voltage divider circuit for R329-02 Hamamatsu PMT was made and Zero Cross method used for neutron-gamma discrimination. The neutron source was a 20Ci Am-Be. Anode and Dynode pulses and discrimination spectrum were saved. The results showed that the pulse height and discrimination quality change with the value and setting of capacitors.« less

Study of the electromagnetic characteristics of multiple HTSPPT modules based on the configuration of toroidal structure for inductive pulsed power supply

NASA Astrophysics Data System (ADS)

Zhang, Cunshan; Zheng, Xinxin; Li, Haitao; Li, Zhenmei; Zhang, Tao; Jiao, Can

2018-04-01

High temperature superconducting pulsed power transformer (HTSPPT) is an important device for pulsed power supplies. It consists of a superconducting primary and a normal conducting secondary, which is used for energy storage and current amplification. The critical current density, the energy storage, and the coupling coefficient are three main performance indexes. They are affected by the geometry parameters of HTSPPT modules, such as the height and the width of the superconducting coils. In addition, the hoop stress of the HTSPPT coils is limited by the maximum tensile strength of high temperature superconducting (HTS) tapes. In this paper, Bi-2223/Ag HTS tapes are selected as the wire of primary inductor and the toroidal structure model is selected for multiple HTSPPT modules. The relationships between the geometry parameters of HTSPPT modules and the electrical performance are studied.

A simple differential pulse polarographic method for the determination of thymoquinone in black seed oil.

PubMed

Michelitsch, Astrid; Rittmannsberger, Anna

2003-01-01

A reliable and simple differential pulse polarographic method is described for the determination of thymoquinone in black seed oil. The polarographic behaviour of thymoquinone was examined in various buffer systems over the pH range 5.0-10.0. Thymoquinone is reduced in a single, reversible peak at the dropping mercury electrode. The differential pulse polarogram showed a distinct peak in Sörensen buffer:methanol (3:7, v/v; pH 8.5) at a peak potential of -0.095 V (vs. silver/silver chloride electrode), and a plot of peak height against concentration was found to be linear over the range 0.2-15.0 microg/mL (R = 0.9998). The limit of detection was calculated to be 0.054 microg/mL. The polarographic method has been applied to determine thymoquinone in two black seed oil preparations available on the Austrian pharmaceutical market.

56Fe capture cross section experiments at the RPI LINAC Center

NASA Astrophysics Data System (ADS)

McDermott, Brian; Blain, Ezekiel; Thompson, Nicholas; Weltz, Adam; Youmans, Amanda; Danon, Yaron; Barry, Devin; Block, Robert; Daskalakis, Adam; Epping, Brian; Leinweber, Gregory; Rapp, Michael

2017-09-01

A new array of C6D6 detectors installed at the RPI LINAC Center has enabled the capability to measure neutron capture cross sections above the 847 keV inelastic scattering threshold of 56Fe through the use of digital post-processing filters and pulse-integral discriminators, without sacrificing the statistical quality of data at lower incident neutron energies where such filtering is unnecessary. The C6D6 detectors were used to perform time-of-flight capture cross section measurements on a sample 99.87% enriched iron-56. The total-energy method, combined with the pulse height weighting technique, were then applied to the raw data to determine the energy-dependent capture yield. Above the inelastic threshold, the data were analyzed with a pulse-integral filter to reveal the capture signal, extending the the full data set to 2 MeV.

Synaptic long-term potentiation realized in Pavlov's dog model based on a NiOx-based memristor

NASA Astrophysics Data System (ADS)

Hu, S. G.; Liu, Y.; Liu, Z.; Chen, T. P.; Yu, Q.; Deng, L. J.; Yin, Y.; Hosaka, Sumio

2014-12-01

Synaptic Long-Term Potentiation (LTP), which is a long-lasting enhancement in signal transmission between neurons, is widely considered as the major cellular mechanism during learning and memorization. In this work, a NiOx-based memristor is found to be able to emulate the synaptic LTP. Electrical conductance of the memristor is increased by electrical pulse stimulation and then spontaneously decays towards its initial state, which resembles the synaptic LTP. The lasting time of the LTP in the memristor can be estimated with the relaxation equation, which well describes the conductance decay behavior. The LTP effect of the memristor has a dependence on the stimulation parameters, including pulse height, width, interval, and number of pulses. An artificial network consisting of three neurons and two synapses is constructed to demonstrate the associative learning and LTP behavior in extinction of association in Pavlov's dog experiment.

Micro pulse laser radar

NASA Technical Reports Server (NTRS)

Spinhirne, James D. (Inventor)

1993-01-01

An eye safe, compact, solid state lidar for profiling atmospheric cloud and aerosol scattering is disclosed. The transmitter of the micro pulse lidar is a diode pumped micro-J pulse energy, high repetition rate Nd:YLF laser. Eye safety is obtained through beam expansion. The receiver employs a photon counting solid state Geiger mode avalanche photodiode detector. Data acquisition is by a single card multichannel scaler. Daytime background induced quantum noise is controlled by a narrow receiver field-of-view and a narrow bandwidth temperature controlled interference filter. Dynamic range of the signal is limited to optical geometric signal compression. Signal simulations and initial atmospheric measurements indicate that micropulse lider systems are capable of detecting and profiling all significant cloud and aerosol scattering through the troposphere and into the stratosphere. The intended applications are scientific studies and environmental monitoring which require full time, unattended measurements of the cloud and aerosol height structure.

The use of a laser ceilometer for sky condition determination

NASA Astrophysics Data System (ADS)

Nadolski, Vickie L.; Bradley, James T.

The use of a laser ceilometer for determining sky condition is presented, with emphasis on the operation of the ceilometer, the sky-condition-reporting algorithm, and how the laser ceilometer and the sky-condition algorithm are used to give a report suitable for aircraft operations and meteorological application. The sampling and processing features of the Vaisala ceilometer produced a detailed and accurate cloud base 'signature' by taking 254 measurement samples of the energy scattered back from a single laser pulse as the pulse traveled from the surface to 12,000 ft. The transmit time from the projection of the laser pulse to its backscattering from a cloud element and subsequent return to a collocated receiver is measured and a cloud height element computed. Attention is given to the development of a vertical visibility concept and of a vertical-visibility algorithm, as well as the strengths and limitations of the sky condition report.

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

Lombigit, L., E-mail: lojius@nm.gov.my; Yussup, N., E-mail: nolida@nm.gov.my; Ibrahim, Maslina Mohd

A digital n/γ pulse shape discrimination (PSD) system is currently under development at Instrumentation and Automation Centre, Malaysian Nuclear Agency. This system aims at simultaneous detection of fast neutron and gamma ray in mixed radiations environment. This work reports the system characterization performed on the liquid scintillation detector (BC-501A) and digital pulse shape discrimination (DPSD) system. The characterization involves measurement of electron light output from the BC-501A detector and energy channels calibration of the pulse height spectra acquired with DPSD system using set of photon reference sources. The main goal of this experiment is to calibrate the ADC channel ofmore » our DPSD system, characterized the BC-501 detector and find the position of Compton edge which later could be used as threshold for the n/γ PSD experiment. The detector resolution however is worse as compared to other published data but it is expected as our detector has a smaller active volume.« less

Inventory of File sref.t03z.pgrb132.prob_3hrly.grib2

Science.gov Websites

] prob <9654 032 cloud ceiling HGT analysis Geopotential Height [prob] prob <152.5 033 cloud ceiling HGT analysis Geopotential Height [prob] prob <305 034 cloud ceiling HGT analysis Geopotential Height [prob] prob <610 035 cloud ceiling HGT analysis Geopotential Height [prob] prob <914.6 036

Inventory of File sref.t03z.pgrb216.prob_3hrly.grib2

Science.gov Websites

] prob <9654 032 cloud ceiling HGT analysis Geopotential Height [prob] prob <152.5 033 cloud ceiling HGT analysis Geopotential Height [prob] prob <305 034 cloud ceiling HGT analysis Geopotential Height [prob] prob <610 035 cloud ceiling HGT analysis Geopotential Height [prob] prob <914.6 036

Inventory of File sref.t03z.pgrb243.prob_3hrly.grib2

Science.gov Websites

] prob <9654 032 cloud ceiling HGT analysis Geopotential Height [prob] prob <152.5 033 cloud ceiling HGT analysis Geopotential Height [prob] prob <305 034 cloud ceiling HGT analysis Geopotential Height [prob] prob <610 035 cloud ceiling HGT analysis Geopotential Height [prob] prob <914.6 036

Microprocessor-based single particle calibration of scintillation counter

NASA Technical Reports Server (NTRS)

Mazumdar, G. K. D.; Pathak, K. M.

1985-01-01

A microprocessor-base set-up is fabricated and tested for the single particle calibration of the plastic scintillator. The single particle response of the scintillator is digitized by an A/D converter, and a 8085 A based microprocessor stores the pulse heights. The digitized information is printed. Facilities for CRT display and cassette storing and recalling are also made available.

Evaluating a small footprint, waveform-resolving lidar over coastal vegetation communities

USGS Publications Warehouse

Nayegandhl, A.; Brock, J.C.; Wright, C.W.; O'Connell, M. J.

2006-01-01

NASA's Experimental Advanced Airborne Research Lidar (EAARL) is a raster-scanning, waveform-resolving, green-wavelength (532 nm) lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor records the time history of the return waveform within a small footprint (20 cm diameter) for each laser pulse, enabling characterization of vegetation canopy structure and "bare earth" topography under a variety of vegetation types. A collection of individual waveforms combined within a synthesized large footprint was used to define three metrics: canopy height (CH), canopy reflection ratio (CRR), and height of median energy (HOME). Bare Earth Elevation (BEE) metric was derived using the individual small-footprint waveforms. All four metrics were tested for reproducibility, which resulted in an average of 95 percent correspondence within two standard deviations of the mean. CH and BEE values were also tested for accuracy using ground-truth data. The results presented in this paper show that combining several individual small-footprint laser pulses to define a composite "large-footprint" waveform is a possible method to depict the vertical structure of a vegetation canopy. ?? 2006 American Society for Photogrammetry and Remote Sensing.

Measurement of keV-neutron capture cross sections and capture gamma-ray spectra of Cs-133 and I-127

NASA Astrophysics Data System (ADS)

Umezawa, Seigo; Igashira, Masayuki; Katabuchi, Tatuya; Dominic, Moraru; Yanagida, Shotaro; Okamiya, Tomohiro

2017-09-01

The neutron capture cross sections and the capture gamma-ray spectra of 127I and 133Cs at incident neutron energies from 15 to 100 keV have been measured by the time-of-flight method. Capture gamma-rays were detected with an anti-Compton NaI(Tl) spectrometer, and the pulse-height weighting technique was applied to derive capture yields. The capture cross sections of 127I and 133Cs were determined using the standard capture cross section of 197Au. The total errors of the cross sections were 3.8-5.1%. The obtained cross sections were compared with evaluated values in JENDL-4.0 and ENDF/B-VII.1. For 127I, the energy dependence is different between the present results and the evaluations. For 133Cs, the evaluated values in JENDL-4.0 agree with the present results but the evaluated values in ENDF/B-VII.1 are smaller than the present results by 14%-18%. The capture gamma-ray spectra of 133Cs and 127I were derived by unfolding the pulse height spectra with detector response functions.

Psycho-Physiological Responses by Listening to Some Sounds from Our Daily Life

NASA Astrophysics Data System (ADS)

Sakamoto, H.; Hayashi, F.; Tsujikawa, M.; Sugiura, S.

1997-08-01

This study was made to clarify the relationship between mode of identification, mode of emotion and physiological response to noise. Twenty-six subjects, young females, listened to six different daily sounds for 150 s through head phones. The level of sound was 60-61LAcq. The pulse wave and blood pressure were observed, and pulse wave interval, wave height and maximum and minimum blood pressures were measured. Measurements were taken twice once 30 s before listening and again during the final 30 s of listening. The ratio of the latter value to the former value was used as the index for the evaluation of change. Immediately after the listening session, identification of the sound source and emotional response were surveyed via a questionnaire and the sounds were judged as related to comfort or discomfort. In the case of incorrect identification, physiological functions were not seen to change significantly. However, in the case of correct identification, maximum and minimum blood pressures were significantly increased form the pre-listening values. The physiological functions of the discomfort group did not change significantly. In the comfort group, wave height was decreased and blood pressure was significantly elevated.

Pulsed Airborne Lidar Measurements of Atmospheric CO2 Column Absorption and Line Shapes from 3-13 km Altitudes

NASA Technical Reports Server (NTRS)

Abshire, James; Riris, Haris; Allan, Graham; Weaver, Clark; Mao, Jianping; Sun, Xiaoli; Hasselbrack, William

2010-01-01

We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's planned ASCENDS space mission. Our technique uses two pulsed laser transmitters allowing simultaneous measurement of a CO2 absorption line in the 1570 nm band, O2 extinction in the Oxygen A-band and surface height and backscatter. The lidar measures the energy and time of flight of the laser echoes reflected from the atmosphere and surface. The lasers are rapidly and precisely stepped in wavelength across the CO2 line and an O2 line region during the measurement. The direct detection receiver uses a telescope and photon counting detectors, and measures the background light and energies of the laser echoes from the surface along with scattering from any aerosols in the path. The gas extinction and column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off- line signals via the DIAL technique. Time gating is used to isolate the laser echo signals from the surface, and to reject laser photons scattered in the atmosphere. The time of flight of the laser pulses are also used to estimate the height of the scattering surface and to identify cases of mixed cloud and ground scattering. We have developed an airborne lidar to demonstrate the CO2 measurement from the NASA Glenn Lear-25 aircraft. The airborne lidar steps the pulsed laser's wavelength across the selected CO2 line with 20 steps per scan. The line scan rate is 450 Hz, the laser pulse widths are 1 usec, and laser pulse energy is 24 uJ. The time resolved laser backscatter is collected by a 20 cm telescope, detected by a photomultiplier and is recorded by a photon counting system. We made initial airborne measurements on flights during fall 2008. Laser backscatter and absorption measurements were made over a variety of land and water surfaces and through thin clouds. The atmospheric CO2 column measurements using the 1572.33 nm CO2 lines. Two flights were made above the US Department of Energy's (DOE) SGP ARM site at altitudes from 3-8 km. These flights were coordinated with DOE investigators who flew an in-situ CO2 sensor on a Cessna aircraft under the path. The increasing CO2 line absorptions with altitudes were evident and comparison with in-situ measurements showed agreements to 6 ppm. In spring 2009 we improved the aircraft's nadir window and during July and August we made 9 additional 2 hour long flights and measured the atmospheric CO2 absorption and line shapes using the 1572.33 nm CO2 line. Measurements were made at stepped altitudes from 3-13 km over a variety of surface types in Nebraska, Illinois, the SGP ARM site, and near and over the Chesapeake Bay in North Carolina and eastern Virginia. Strong laser signals and clear CO2 line shapes were observed at all altitudes, and some measurements were made through thin clouds. The flights over the ARM site were underflown with in-situ measurements made from the DOE Cessna. Analysis shows that the average signal levels follow predicted values, the altimetry measurements had an uncertainty of about 4 m, and that the average optical line depths follow the number density calculated from in-situ sensor readings. The Oklahoma and east coast flights were coordinated with a LaRC/ITT CO2 lidar on the LaRC UC-12 aircraft, a LaRC in-situ CO2 sensor, and the Oklahoma flights also included a JPL CO2 lidar on a Twin Otter aircraft. More details of the flights, measurements, analysis and scaling to space will be described in the presentation.

Evaluating the Height of Biomass Burning Smoke Aerosols Retrieved from Synergistic Use of Multiple Satellite Sensors Over Southeast Asia

NASA Technical Reports Server (NTRS)

Lee, Jaehwa; Hsu, N. Christina; Bettenhausen, Corey; Sayer, Andrew M.; Seftor, Colin J.; Jeong, Myeong-Jae; Tsay, Si-Chee; Welton, Ellsworth J.; Wang, Sheng-Hsiang; Chen, Wei-Nai

2016-01-01

This study evaluates the height of biomass burning smoke aerosols retrieved from a combined use of Visible Infrared Imaging Radiometer Suite (VIIRS), Ozone Mapping and Profiler Suite (OMPS), and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations. The retrieved heights are compared against space borne and ground-based lidar measurements during the peak biomass burning season (March and April) over Southeast Asia from 2013 to 2015. Based on the comparison against CALIOP, a quality assurance (QA) procedure is developed. It is found that 74 (8184) of the retrieved heights fall within 1 km of CALIOP observations for unfiltered (QA-filtered) data, with root-mean-square error (RMSE) of 1.1 km (0.81.0 km). Eliminating the requirement of CALIOP observations from the retrieval process significantly increases the temporal coverage with only a slight decrease in the retrieval accuracy; for best QA data, 64 of data fall within 1 km of CALIOP observations with RMSE of 1.1 km. When compared with Micro-Pulse Lidar Network (MPLNET) measurements deployed at Doi Ang Khang, Thailand, the retrieved heights show RMSE of 1.7 km (1.1 km) for unfiltered (QA-filtered) data for the complete algorithm, and 0.9 km (0.8 km) for the simplified algorithm.

Skin contamination dosimeter

DOEpatents

Hamby, David M [Corvallis, OR; Farsoni, Abdollah T [Corvallis, OR; Cazalas, Edward [Corvallis, OR

2011-06-21

A technique and device provides absolute skin dosimetry in real time at multiple tissue depths simultaneously. The device uses a phoswich detector which has multiple scintillators embedded at different depths within a non-scintillating material. A digital pulse processor connected to the phoswich detector measures a differential distribution (dN/dH) of count rate N as function of pulse height H for signals from each of the multiple scintillators. A digital processor computes in real time from the differential count-rate distribution for each of multiple scintillators an estimate of an ionizing radiation dose delivered to each of multiple depths of skin tissue corresponding to the multiple scintillators embedded at multiple corresponding depths within the non-scintillating material.

On noise treatment in radio measurements of cosmic ray air showers

NASA Astrophysics Data System (ADS)

Schröder, F. G.; Apel, W. D.; Arteaga, J. C.; Asch, T.; Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Buchholz, P.; Buitink, S.; Cantoni, E.; Chiavassa, A.; Daumiller, K.; de Souza, V.; Doll, P.; Engel, R.; Falcke, H.; Finger, M.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer, A.; Huber, D.; Huege, T.; Isar, P. G.; Kampert, K.-H.; Kang, D.; Krömer, O.; Kuijpers, J.; Lafebre, S.; Link, K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello, C.; Nehls, S.; Oehlschläger, J.; Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski, J.; Zensus, J. A.

2012-01-01

Precise measurements of the radio emission by cosmic ray air showers require an adequate treatment of noise. Unlike to usual experiments in particle physics, where noise always adds to the signal, radio noise can in principle decrease or increase the signal if it interferes by chance destructively or constructively. Consequently, noise cannot simply be subtracted from the signal, and its influence on amplitude and time measurement of radio pulses must be studied with care. First, noise has to be determined consistently with the definition of the radio signal which typically is the maximum field strength of the radio pulse. Second, the average impact of noise on radio pulse measurements at individual antennas is studied for LOPES. It is shown that a correct treatment of noise is especially important at low signal-to-noise ratios: noise can be the dominant source of uncertainty for pulse height and time measurements, and it can systematically flatten the slope of lateral distributions. The presented method can also be transferred to other experiments in radio and acoustic detection of cosmic rays and neutrinos.

The effectiveness of nutrition education: Applying the Health Belief Model in child-feeding practices to use pulses for complementary feeding in Southern Ethiopia.

PubMed

Mulualem, Demmelash; Henry, Carol J; Berhanu, Getenesh; Whiting, Susan J

2016-01-01

Complementary foods (CFs) in Ethiopia are cereal based and adding locally grown pulses (legumes) to CF would provide needed nutrients. To assess the effects of nutrition education (NEd) using Health Belief Model (HBM) in promoting pulses for CF, a 6-month quasi-experimental study was conducted in 160 mother-child pairs. Knowledge, attitude, and practice (KAP) questions were given to mothers at baseline, midline, and endline, along with anthropometric measurements of children. NEd involving discussions and recipe demonstrations was given twice monthly for 6 months to the intervention group (n = 80) while control mothers received usual education. At baseline, mothers' KAP scores were low at both sites; at 3 and 6 months of NEd, mean KAP scores of mothers increased (p < 0.05) compared to the control site. Significant improvements in children's mean weight, weight for height, and weight for age occurred in the intervention site only. Nutritional status of children improved after providing mothers with pulse-based NEd.

Use of SRIM and Garfield with Geant4 for the characterization of a hybrid 10B/3He neutron detector

NASA Astrophysics Data System (ADS)

van der Ende, B. M.; Rand, E. T.; Erlandson, A.; Li, L.

2018-06-01

This paper describes a method for more complete neutron detector characterization using Geant4's Monte Carlo methods for characterizing overall detector response rate and Garfield interfaced with SRIM for the simulation of the detector's raw pulses, as applied to a hybrid 10B/3He detector. The Geant4 models characterizing the detector's interaction with a 252Cf point source and parallel beams of mono-energetic neutrons (assuming ISO 8529 reference energy values) compare and agree well with calibrated 252Cf measurements to within 6.4%. Validated Geant4 model outputs serve as input to Garfield+SRIM calculations to provide meaningful pulse height spectra. Modifications to Garfield for this work were necessary to account for simultaneous tracking of electrons resulting from proton and triton reaction products from a single 3He neutron capture event, and it was further necessary to interface Garfield with the energy loss, range, and straggling calculations provided by SRIM. Individual raw pulses generated by Garfield+SRIM are also observed to agree well with experimentally measured raw pulses from the detector.

Growth hormone secretion in Turner's syndrome and influence of oxandrolone and ethinyl oestradiol.

PubMed

Massarano, A A; Brook, C G; Hindmarsh, P C; Pringle, P J; Teale, J D; Stanhope, R; Preece, M A

1989-04-01

We investigated 24 hour growth hormone secretion by intermittent 20 minute blood sampling in 34 prepubertal patients with Turner's syndrome, aged 4.3-12.4 years. Growth hormone profiles were analysed by the PULSAR programme and results expressed as the sum of growth hormone pulse amplitudes. Six patients had abnormal growth hormone pulse frequencies. In the remaining 28, growth hormone pulse amplitudes declined significantly with increasing age, but there was no correlation between growth hormone pulse amplitudes and growth rates. Concentrations of insulin like growth factor-1 (IGF-1) rose with age but did not correlate with either growth rates or growth hormone secretion. Fifteen patients were given oxandrolone and 11 low dose ethinyl oestradiol. Both agents increased height velocity without increasing growth hormone secretion. We conclude that the relation between growth hormone secretion and growth in Turner's syndrome is less certain than in normal children. End organ resistance is probably due to a skeletal dysplasia. Both oxandrolone and low dose ethinyl oestradiol improve the growth of girls with Turner's syndrome, but their mechanism of action remains uncertain.

Requirements and Technology Advances for Global Wind Measurement with a Coherent Lidar: A Shrinking Gap

NASA Technical Reports Server (NTRS)

Kavaya, Michael J.; Kavaya, Michael J.; Yu, Jirong; Koch, Grady J.; Amzajerdian, Farzin; Singh, Upendra N.; Emmitt, G. David

2007-01-01

Early concepts to globally measure vertical profiles of vector horizontal wind from space planned on an orbit height of 525 km, a single pulsed coherent Doppler lidar system to cover the full troposphere, and a continuously rotating telescope/scanner that mandated a vertical line of sight wind profile from each laser shot. Under these conditions system studies found that laser pulse energies of approximately 20 J at 10 Hz pulse repetition rate with a rotating telescope diameter of approximately 1.5 m was required. Further requirements to use solid state laser technology and an eyesafe wavelength led to the relatively new 2-micron solid state laser. With demonstrated pulse energies near 20 mJ at 5 Hz, and no demonstration of a rotating telescope maintaining diffraction limited performance in space, the technology gap between requirements and demonstration was formidable. Fortunately the involved scientists and engineers set out to reduce the gap, and through a combination of clever ideas and technology advances over the last 15 years, they have succeeded. This paper will detail the gap reducing factors and will present the current status.

Low-amplitude pulses to the circulation through periodic acceleration induces endothelial-dependent vasodilatation.

PubMed

Uryash, Arkady; Wu, Heng; Bassuk, Jorge; Kurlansky, Paul; Sackner, Marvin A; Adams, Jose A

2009-06-01

Low-amplitude pulses to the vasculature increase pulsatile shear stress to the endothelium. This activates endothelial nitric oxide (NO) synthase (eNOS) to promote NO release and endothelial-dependent vasodilatation. Descent of the dicrotic notch on the arterial pulse waveform and a-to-b ratio (a/b; where a is the height of the pulse amplitude and b is the height of the dicrotic notch above the end-diastolic level) reflects vasodilator (increased a/b) and vasoconstrictor effects (decreased a/b) due to NO level change. Periodic acceleration (pG(z)) (motion of the supine body head to foot on a platform) provides systemic additional pulsatile shear stress. The purpose of this study was to determine whether or not pG(z) applied to rats produced endothelial-dependent vasodilatation and increased NO production, and whether the latter was regulated by the Akt/phosphatidylinositol 3-kinase (PI3K) pathway. Male rats were anesthetized and instrumented, and pG(z) was applied. Sodium nitroprusside, N(G)-nitro-l-arginine methyl ester (l-NAME), and wortmannin (WM; to block Akt/PI3K pathway) were administered to compare changes in a/b and mean aortic pressure. Descent of the dicrotic notch occurred within 2 s of initiating pG(z). Dose-dependent increase of a/b and decrease of mean aortic pressure took place with SNP. l-NAME produced a dose-dependent rise in mean aortic pressure and decrease of a/b, which was blunted with pG(z). In the presence of WM, pG(z) did not decrease aortic pressure or increase a/b. WM also abolished the pG(z) blunting effect on blood pressure and a/b of l-NAME-treated animals. eNOS expression was increased in aortic tissue after pG(z). This study indicates that addition of low-amplitude pulses to circulation through pG(z) produces endothelial-dependent vasodilatation due to increased NO in rats, which is mediated via activation of eNOS, in part, by the Akt/PI3K pathway.

Theoretical Study of Molecular Transport Through a Permeabilized Cell Membrane in a Microchannel.

PubMed

Mahboubi, Masoumeh; Movahed, Saeid; Hosseini Abardeh, Reza; Hoshyargar, Vahid

2017-06-01

A two-dimensional model is developed to study the molecular transport into an immersed cell in a microchannel and to investigate the effects of finite boundary (a cell is suspended in a microchannel), amplitude of electric pulse, and geometrical parameter (microchannel height and size of electrodes) on cell uptake. Embedded electrodes on the walls of the microchannel generate the required electric pulse to permeabilize the cell membrane, pass the ions through the membrane, and transport them into the cell. The shape of electric pulses is square with the time span of 6 ms; their intensities are in the range of 2.2, 2.4, 2.6, 3 V. Numerical simulations have been performed to comprehensively investigate the molecular uptake into the cell. The obtained results of the current study demonstrate that calcium ions enter the cell from the anodic side (the side near positive electrode); after a while, the cell faces depletion of the calcium ions on a positive electrode-facing side within the microchannel; the duration of depletion depends on the amplitude of electric pulse and geometry that lasts from microseconds to milliseconds. By keeping geometrical parameters and time span constant, increment of a pulse intensity enhances molecular uptake and rate of propagation inside the cell. If a ratio of electrode size to cell diameter is larger than 1, the transported amount of Ca 2+ into the cell, as well as the rate of propagation, will be significantly increased. By increasing the height of the microchannel, the rate of uptake is decreased. In an infinite domain, the peak concentration becomes constant after reaching the maximum value; this value depends on the intra-extracellular conductivity and diffusion coefficient of interior and exterior domains of the cell. In comparison, the maximum concentration is changed by geometrical parameters in the microchannel. After reaching the maximum value, the peak concentration reduces due to the depletion of Ca 2+ ions within the microchannel. Electrophoretic velocity has a significant effect on the cell uptake.

A feasibility study on age-related factors of wrist pulse using principal component analysis.

PubMed

Jang-Han Bae; Young Ju Jeon; Sanghun Lee; Jaeuk U Kim

2016-08-01

Various analysis methods for examining wrist pulse characteristics are needed for accurate pulse diagnosis. In this feasibility study, principal component analysis (PCA) was performed to observe age-related factors of wrist pulse from various analysis parameters. Forty subjects in the age group of 20s and 40s were participated, and their wrist pulse signal and respiration signal were acquired with the pulse tonometric device. After pre-processing of the signals, twenty analysis parameters which have been regarded as values reflecting pulse characteristics were calculated and PCA was performed. As a results, we could reduce complex parameters to lower dimension and age-related factors of wrist pulse were observed by combining-new analysis parameter derived from PCA. These results demonstrate that PCA can be useful tool for analyzing wrist pulse signal.

Stochastic modeling of hourly rainfall times series in Campania (Italy)

NASA Astrophysics Data System (ADS)

Giorgio, M.; Greco, R.

2009-04-01

Occurrence of flowslides and floods in small catchments is uneasy to predict, since it is affected by a number of variables, such as mechanical and hydraulic soil properties, slope morphology, vegetation coverage, rainfall spatial and temporal variability. Consequently, landslide risk assessment procedures and early warning systems still rely on simple empirical models based on correlation between recorded rainfall data and observed landslides and/or river discharges. Effectiveness of such systems could be improved by reliable quantitative rainfall prediction, which can allow gaining larger lead-times. Analysis of on-site recorded rainfall height time series represents the most effective approach for a reliable prediction of local temporal evolution of rainfall. Hydrological time series analysis is a widely studied field in hydrology, often carried out by means of autoregressive models, such as AR, ARMA, ARX, ARMAX (e.g. Salas [1992]). Such models gave the best results when applied to the analysis of autocorrelated hydrological time series, like river flow or level time series. Conversely, they are not able to model the behaviour of intermittent time series, like point rainfall height series usually are, especially when recorded with short sampling time intervals. More useful for this issue are the so-called DRIP (Disaggregated Rectangular Intensity Pulse) and NSRP (Neymann-Scott Rectangular Pulse) model [Heneker et al., 2001; Cowpertwait et al., 2002], usually adopted to generate synthetic point rainfall series. In this paper, the DRIP model approach is adopted, in which the sequence of rain storms and dry intervals constituting the structure of rainfall time series is modeled as an alternating renewal process. Final aim of the study is to provide a useful tool to implement an early warning system for hydrogeological risk management. Model calibration has been carried out with hourly rainfall hieght data provided by the rain gauges of Campania Region civil protection agency meteorological warning network. ACKNOWLEDGEMENTS The research was co-financed by the Italian Ministry of University, by means of the PRIN 2006 PRIN program, within the research project entitled ‘Definition of critical rainfall thresholds for destructive landslides for civil protection purposes'. REFERENCES Cowpertwait, P.S.P., Kilsby, C.G. and O'Connell, P.E., 2002. A space-time Neyman-Scott model of rainfall: Empirical analysis of extremes, Water Resources Research, 38(8):1-14. Salas, J.D., 1992. Analysis and modeling of hydrological time series, in D.R. Maidment, ed., Handbook of Hydrology, McGraw-Hill, New York. Heneker, T.M., Lambert, M.F. and Kuczera G., 2001. A point rainfall model for risk-based design, Journal of Hydrology, 247(1-2):54-71.

Ultrasonic device for real-time sewage velocity and suspended particles concentration measurements.

PubMed

Abda, F; Azbaid, A; Ensminger, D; Fischer, S; François, P; Schmitt, P; Pallarès, A

2009-01-01

In the frame of a technological research and innovation network in water and environment technologies (RITEAU, Réseau de Recherche et d'Innovation Technologique Eau et Environnement), our research group, in collaboration with industrial partners and other research institutions, has been in charge of the development of a suitable flowmeter: an ultrasonic device measuring simultaneously the water flow and the concentration of size classes of suspended particles. Working on the pulsed ultrasound principle, our multi-frequency device (1 to 14 MHz) allows flow velocity and water height measurement and estimation of suspended solids concentration. Velocity measurements rely on the coherent Doppler principle. A self developed frequency estimator, so called Spectral Identification method, was used and compared to the classical Pulse-Pair method. Several measurements campaigns on one wastewater collector of the French city of Strasbourg gave very satisfactory results and showed smaller standard deviation values for the Doppler frequency extracted by the Spectral Identification method. A specific algorithm was also developed for the water height measurements. It relies on the water surface acoustic impedance rupture and its peak localisation and behaviour in the collected backscattering data. This algorithm was positively tested on long time measurements on the same wastewater collector. A large part of the article is devoted to the measurements of the suspended solids concentrations. Our data analysis consists in the adaptation of the well described acoustic behaviour of sand to the behaviour of wastewater particles. Both acoustic attenuation and acoustic backscattering data over multiple frequencies are analyzed for the extrapolation of size classes and respective concentrations. Under dry weather conditions, the massic backscattering coefficient and the overall size distribution showed similar evolution whatever the measurement site was and were suggesting a global wastewater particles behaviour. By comparison to sampling data, our data analysis lead to the characterization of two particle groups: the ones occurring during rain events and the ones typical of wastewater under dry weather conditions. Even with already encouraging results on the several weeks of data recorded on several wastewater collectors, the validation of our data inversion method is still under progress.

Resonant-cavity apparatus for cytometry or particle analysis

DOEpatents

Gourley, P.L.

1998-08-11

A resonant-cavity apparatus for cytometry or particle analysis is described. The apparatus comprises a resonant optical cavity having an analysis region within the cavity for containing one or more biological cells or dielectric particles to be analyzed. In the presence of a cell or particle, a light beam in the form of spontaneous emission or lasing is generated within the resonant optical cavity and is encoded with information about the cell or particle. An analysis means including a spectrometer and/or a pulse-height analyzer is provided within the apparatus for recovery of the information from the light beam to determine a size, shape, identification or other characteristics about the cells or particles being analyzed. The recovered information can be grouped in a multi-dimensional coordinate space for identification of particular types of cells or particles. In some embodiments of the apparatus, the resonant optical cavity can be formed, at least in part, from a vertical-cavity surface-emitting laser. The apparatus and method are particularly suited to the analysis of biological cells, including blood cells, and can further include processing means for manipulating, sorting, or eradicating cells after analysis. 35 figs.

Thermal imaging diagnostics of high-current electron beams.

PubMed

Pushkarev, A; Kholodnaya, G; Sazonov, R; Ponomarev, D

2012-10-01

The thermal imaging diagnostics of measuring pulsed electron beam energy density is presented. It provides control of the electron energy spectrum and a measure of the density distribution of the electron beam cross section, the spatial distribution of electrons with energies in the selected range, and the total energy of the electron beam. The diagnostics is based on the thermal imager registration of the imaging electron beam thermal print in a material with low bulk density and low thermal conductivity. Testing of the thermal imaging diagnostics has been conducted on a pulsed electron accelerator TEU-500. The energy of the electrons was 300-500 keV, the density of the electron current was 0.1-0.4 kA/cm(2), the duration of the pulse (at half-height) was 60 ns, and the energy in the pulse was up to 100 J. To register the thermal print, a thermal imager Fluke-Ti10 was used. Testing showed that the sensitivity of a typical thermal imager provides the registration of a pulsed electron beam heat pattern within one pulse with energy density over 0.1 J/cm(2) (or with current density over 10 A/cm(2), pulse duration of 60 ns and electron energy of 400 keV) with the spatial resolution of 0.9-1 mm. In contrast to the method of using radiosensitive (dosimetric) materials, thermal imaging diagnostics does not require either expensive consumables, or plenty of processing time.

Measurement of Aortic Pulse Wave Velocity With a Connected Bathroom Scale

PubMed Central

Campo, David; Khettab, Hakim; Yu, Roger; Genain, Nicolas; Edouard, Paul; Buard, Nadine

2017-01-01

Abstract BACKGROUND Measurement of arterial stiffness should be more available. Our aim was to show that aortic pulse wave velocity can be reliably measured with a bathroom scale combining the principles of ballistocardiography (BCG) and impedance plethysmography on a single foot. METHOD The calibration of the bathroom scale was conducted on a group of 106 individuals. The aortic pulse wave velocity was measured with the SphygmoCor in the supine position. Three consecutive measurements were then performed on the Withings scale in the standing position. This aorta-leg pulse transit time (alPTT) was then converted into a velocity with the additional input of the height of the person. Agreement between the SphygmoCor and the bathroom scale so calibrated is assessed on a separate group of 86 individuals, following the same protocol. RESULTS The bias is 0.25 m·s−1 and the SE 1.39 m·s−1. This agreement with Sphygmocor is “acceptable” according to the ARTERY classification. The alPTT correlated well with cfPTT with (Spearman) R = 0.73 in pooled population (cal 0.79, val 0.66). The aorta-leg pulse wave velocity correlated with carotid-femoral pulse wave velocity with R = 0.76 (cal 0.80, val 0.70). CONCLUSION Estimation of the aortic pulse wave velocity is feasible with a bathroom scale. Further investigations are needed to improve the repeatability of measurements and to test their accuracy in different populations and conditions. PMID:28520843

Study of Static Microchannel Plate Saturation Effects for the Fast Plasma Investigation Dual Electron Spectrometers on NASA's Magnetospheric MultiScale Mission

NASA Technical Reports Server (NTRS)

Avanov, L. A.; Gliese, U.; Pollock, C. J.; Moore, T. E.; Chornay, D. J.; Barrie, A. C.; Kujawski, J. T.; Gershman, D. J.; Tucker, C. J.; Mariano, A.;

Exposure to Radiofrequency Radiation Emitted from Common Mobile Phone Jammers Alters the Pattern of Muscle Contractions: an Animal Model Study

PubMed Central

Rafati, A.; Rahimi, S.; Talebi, A.; Soleimani, A.; Haghani, M.; Mortazavi, S. M. J.

2015-01-01

Introduction The rapid growth of wireless communication technologies has caused public concerns regarding the biological effects of electromagnetic radiations on human health. Some early reports indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians such as the alterations of the pattern of muscle extractions. This study is aimed at investigating the effects of exposure to radiofrequency (RF) radiation emitted from mobile phone jammers on the pulse height of contractions, the time interval between two subsequent contractions and the latency period of frog’s isolated gastrocnemius muscle after stimulation with single square pulses of 1V (1 Hz). Materials and Methods Frogs were kept in plastic containers in a room. Animals in the jammer group were exposed to radiofrequency (RF) radiation emitted from a common Jammer at a distance of 1m from the jammer’s antenna for 2 hours while the control frogs were only sham exposed. Then animals were sacrificed and isolated gastrocnemius muscles were exposed to on/off jammer radiation for 3 subsequent 10 minute intervals. Isolated gastrocnemius muscles were attached to the force transducer with a string. Using a PowerLab device (26-T), the pattern of muscular contractions was monitored after applying single square pulses of 1V (1 Hz) as stimuli. Results The findings of this study showed that the pulse height of muscle contractions could not be affected by the exposure to electromagnetic fields. However, the latency period was effectively altered in RF-exposed samples. However, none of the experiments could show an alteration in the time interval between two subsequent contractions after exposure to electromagnetic fields. Conclusion These findings support early reports which indicated a wide variety of non-thermal effects of electromagnetic radiation on amphibians including the effects on the pattern of muscle extractions. PMID:26396969

Charged-particle spectroscopy in organic semiconducting single crystals

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

Ciavatti, A.; Basiricò, L.; Fraboni, B.

2016-04-11

The use of organic materials as radiation detectors has grown, due to the easy processability in liquid phase at room temperature and the possibility to cover large areas by means of low cost deposition techniques. Direct charged-particle detectors based on solution-grown Organic Semiconducting Single Crystals (OSSCs) are shown to be capable to detect charged particles in pulse mode, with very good peak discrimination. The direct charged-particle detection in OSSCs has been assessed both in the planar and in the vertical axes, and a digital pulse processing algorithm has been used to perform pulse height spectroscopy and to study the chargemore » collection efficiency as a function of the applied bias voltage. Taking advantage of the charge spectroscopy and the good peak discrimination of pulse height spectra, an Hecht-like behavior of OSSCs radiation detectors is demonstrated. It has been possible to estimate the mobility-lifetime value in organic materials, a fundamental parameter for the characterization of radiation detectors, whose results are equal to μτ{sub coplanar} = (5 .5 ± 0.6 ) × 10{sup −6} cm{sup 2}/V and μτ{sub sandwich} = (1 .9 ± 0.2 ) × 10{sup −6} cm{sup 2}/V, values comparable to those of polycrystalline inorganic detectors. Moreover, alpha particles Time-of-Flight experiments have been carried out to estimate the drift mobility value. The results reported here indicate how charged-particle detectors based on OSSCs possess a great potential as low-cost, large area, solid-state direct detectors operating at room temperature. More interestingly, the good detection efficiency and peak discrimination observed for charged-particle detection in organic materials (hydrogen-rich molecules) are encouraging for their further exploitation in the detection of thermal and high-energy neutrons.« less

Rainfall height stochastic modelling as a support tool for landslides early warning

NASA Astrophysics Data System (ADS)

Capparelli, G.; Giorgio, M.; Greco, R.; Versace, P.

2009-04-01

Occurrence of landslides is uneasy to predict, since it is affected by a number of variables, such as mechanical and hydraulic soil properties, slope morphology, vegetation coverage, rainfall spatial and temporal variability. Although heavy landslides frequently occurred in Campania, southern Italy, during the last decade, no complete data sets are available for natural slopes where landslides occurred. As a consequence, landslide risk assessment procedures and early warning systems in Campania still rely on simple empirical models based on correlation between daily rainfall records and observed landslides, like FLAIR model [Versace et al., 2003]. Effectiveness of such systems could be improved by reliable quantitative rainfall prediction. In mountainous areas, rainfall spatial and temporal variability are very pronounced due to orographic effects, making predictions even more complicated. Existing rain gauge networks are not dense enough to resolve the small scale spatial variability, and the same limitation of spatial resolution affects rainfall height maps provided by radar sensors as well as by meteorological physically based models. Therefore, analysis of on-site recorded rainfall height time series still represents the most effective approach for a reliable prediction of local temporal evolution of rainfall. Hydrological time series analysis is a widely studied field in hydrology, often carried out by means of autoregressive models, such as AR and ARMA [Box and Jenkins, 1976]. Sometimes exogenous information coming from additional series of observations is also taken into account, and the models are called ARX and ARMAX (e.g. Salas [1992]). Such models gave the best results when applied to the analysis of autocorrelated hydrological time series, like river flow or level time series. Conversely, they are not able to model the behaviour of intermittent time series, like point rainfall height series usually are, especially when recorded with short sampling time intervals. More useful for this issue are the so-called DRIP (Disaggregated Rectangular Intensity Pulse) and NSRP (Neymann-Scott Rectangular Pulse) model [Heneker et al., 2001; Cowpertwait et al., 2002], usually adopted to generate synthetic point rainfall series. In this paper, the DRIP model approach is adopted in conjunction with FLAIR model to calculate the probability of flowslides occurrence. The final aim of the study is in fact to provide a useful tool to implement an early warning system for hydrogeological risk management. Model calibration has been carried out with hourly rainfall hieght data provided by the rain gauges of Campania Region civil protection agency meteorological warning network. So far, the model has been applied only to data series recorded at a single rain gauge. Future extension will deal with spatial correlation between time series recorded at different gauges. ACKNOWLEDGEMENTS The research was co-financed by the Italian Ministry of University, by means of the PRIN 2006 PRIN program, within the research project entitled ‘Definition of critical rainfall thresholds for destructive landslides for civil protection purposes'. REFERENCES Box, G.E.P. and Jenkins, G.M., 1976. Time Series Analysis Forecasting and Control, Holden-Day, San Francisco. Cowpertwait, P.S.P., Kilsby, C.G. and O'Connell, P.E., 2002. A space-time Neyman-Scott model of rainfall: Empirical analysis of extremes, Water Resources Research, 38(8):1-14. Salas, J.D., 1992. Analysis and modeling of hydrological time series, in D.R. Maidment, ed., Handbook of Hydrology, McGraw-Hill, New York. Heneker, T.M., Lambert, M.F. and Kuczera G., 2001. A point rainfall model for risk-based design, Journal of Hydrology, 247(1-2):54-71. Versace, P., Sirangelo. B. and Capparelli, G., 2003. Forewarning model of landslides triggered by rainfall. Proc. 3rd International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment, Davos.

Prompt Neutron Spectrometry for Identification of SNM in Unknown Shielding Configurations: FY16 ONR YIP Final Report

DTIC Science & Technology

2016-05-31

UMKC-YIP-TR-2016 May 2016 Technical Report Prompt Neutron Spectrometry for Identification of SNM in Unknown Shielding...University of Missouri – Kansas City MSND: Micro-structured Neutron Detector HRM: Handheld Radiation Monitor PHS: Pulse Height Spectrum ANI: Active... Neutron Interrogation Distribution Statement A 6 Administrative Information and Acknowledgements Members of the University of Missouri

Airborne Lidar Measurements of Below-canopy Surface Water Height , Slope and Optical Properties in the Florida Everglades Shark River Slough

NASA Astrophysics Data System (ADS)

Dabney, P.; Harding, D. J.; Valett, S. R.; Yu, A. W.; Feliciano, E. A.; Neuenschwander, A. L.; Pitts, K.

2015-12-01

Determining the presence, persistence, optical properties and variation in height and slope of surface water beneath the dense canopies of flooded forests and mangrove stands could contribute to studies of the acquisition of water and nutrients by plant roots. NASA's airborne Slope Imaging Multi-polarization Photon-counting Lidar (SIMPL) provides unique capabilities that can identify below-canopy surface water, measure its height with respect to vegetation constituents with sub-decimeter precision and quantify its slope. It also provides information on canopy structure and closure, the water column extinction profile as a proxy for turbidity and water depth, with the penetration depth constrained by turbidity. It achieves this by using four laser beams operating at two wavelengths with measurements of water surface elevation at 1064 nm (near infrared) and water column properties at 532 nm (green), analogous to a bathymetric lidar. Importantly the instrument adds a polarimetry function, like some atmospheric lidars, which measures the amount of depolarization determined by the degree to which the plane-parallel transmitted laser pulse energy is converted to the perpendicular state. The degree of depolarization is sensitive to the number of photon multiple-scattering events. For the water surface, which is specular consisting only of single-scattering events, the near-infrared received signal retains the parallel polarization state. Absence of the perpendicular signal uniquely identifies surface water. Penetration of green light and the depth profile of photons converted to the perpendicular state compared to those in the parallel state is a measure of water-column multiple scattering, providing a relative measure of turbidity. The amount of photons reflected from the canopy versus the water provides a wavelength-dependent measure of canopy closure. By rapidly firing laser pulses (11,400 pulses per second) with a narrow width (1 nsec) and detecting single photons with 8 cm ranging precision, the surface altimetry data is acquired with very high spatial and vertical resolution. Examples of these capabilities will be shown using data collected in 2011 along and across the flow axis of the Florida Everglades Shark River Slough, targeting the slough's Long Term Ecology Research (LTER) field sites.

Ultrasound analysis of mental artery flow in elderly patients: a case–control study

PubMed Central

Baladi, Marina G; Tucunduva Neto, Raul R C M; Aoki, Eduardo M; Arita, Emiko S; Freitas, Claudio F

2015-01-01

Objectives: Mental artery flow decreases with age and may have an aetiological role in alveolar ridge atrophy. The aim of this study was to identify factors associated with alterations of mental artery flow, assessed by ultrasonography. Methods: This case–control study was conducted on elderly patients (aged above 60 years) at the beginning of dental treatment. Intraoral B-mode Doppler ultrasonography was used to assess mental artery flow. The cases were defined as patients with a weak/absent ultrasound signal, whereas the controls presented a strong ultrasound signal. Demographics and radiographic findings (low bone mineral density on dual-energy X-ray absorptiometry and mandibular cortical index on panoramic radiographs) were analysed as risk factors for weak/absent ultrasound signal and were calculated as adjusted odds ratios (AORs) with 95% confidence intervals (CIs) using conditional logistic regression. In addition, the Student's t-test was used to compare the mean alveolar bone height of the analysed groups. A p-value <0.05 was considered statistically significant. Results: A total of 30 ultrasound examinations (12 cases and 18 controls) were analysed. A weak/absent mental artery pulse strength was significantly associated with edentulism (AOR = 3.67; 95% CI = 0.86–15.63; p = 0.046). In addition, there was a significant difference in alveolar bone height between edentulous cases and controls (p = 0.036). Conclusions: Within the limitations of this study, the present results indicate that edentulism is associated with diminished mental artery flow, which, in turn, affects alveolar bone height. PMID:26205777

Shuttle Laser Altimeter (SLA): A pathfinder for space-based laser altimetry and lidar

NASA Technical Reports Server (NTRS)

Bufton, Jack; Blair, Bryan; Cavanaugh, John; Garvin, James

1995-01-01

The Shuttle Laser Altimeter (SLA) is a Hitchhiker experiment now being integrated for first flight on STS-72 in November 1995. Four Shuttle flights of the SLA are planned at a rate of about a flight every 18 months. They are aimed at the transition of the Goddard Space Flight Center airborne laser altimeter and lidar technology to low Earth orbit as a pathfinder for operational space-based laser remote sensing devices. Future alser altimeter sensors such as the Geoscience Laser Altimeter System (GLAS), an Earth Observing System facility instrument, and the Multi-Beam Laser Altimeter (MBLA), the land and vegetation laser altimeter for the NASA TOPSAT (Topography Satellite) Mission, will utilize systems and approaches being tested with SLA. The SLA Instrument measures the distance from the Space Shuttle to the Earth's surface by timing the two-way propagation of short (approximately 10 na noseconds) laser pulses. laser pulses at 1064 nm wavelength are generated in a laser transmitter and are detected by a telescope equipped with a silicon avalanche photodiode detector. The SLA data system makes the pulse time interval measurement to a precision of about 10 nsec and also records the temporal shape of the laser echo from the Earth's surface for interpretation of surface height distribution within the 100 m diam. sensor footprint. For example, tree height can be determined by measuring the characteristic double-pulse signature that results from a separation in time of laser backscatter from tree canopies and the underlying ground. This is accomplished with a pulse waveform digitizer that samples the detector output with an adjustable resolution of 2 nanoseconds or wider intervals in a 100 sample window centered on the return pulse echo. The digitizer makes the SLA into a high resolution surface lidar sensor. It can also be used for cloud and atmospheric aerosol lidar measurements by lengthening the sampling window and degrading the waveform resolution. Detailed test objectives for the STS-72 mission center on the acquisition of sample data sets for land topography and vegetation height, waveform digitizer performance, and verification of data acquisition algorithms. The operational concept of SLA is illustrated in Fig. 1 where a series of 100 m footprints stretch in a profile of Earth surface topography along the nadir track of the Space Shuttle. The location of SLA as a dual canister payload on the Hitchhiker Bridge Assembly in Bay 12 of the Space Shuttle Endeavor can also be noted in this figure. Full interpretation of the SLA range measurement data set requires a 1 m knowledge of the Orbiter trajectory and better than 0.1 deg knowledge of Orbiter pointing angle. These ancillary data sets will be acquired during the STS-72 mission with an on-board Global Positioning System (GPS) receiver, K-band range and range-rate tracking of the Orbiter through TDRSS, and use of on-board inertial measurement units and star trackers. Integration and interpretation of all these different data sets as a pathfinder investigation for accurate determination of Earth surface elevation is the overall science of the SLA investigation.

Influence of vegetation structure on lidar-derived canopy height and fractional cover in forested riparian buffers during leaf-off and leaf-on conditions.

PubMed

Wasser, Leah; Day, Rick; Chasmer, Laura; Taylor, Alan

2013-01-01

Estimates of canopy height (H) and fractional canopy cover (FC) derived from lidar data collected during leaf-on and leaf-off conditions are compared with field measurements from 80 forested riparian buffer plots. The purpose is to determine if existing lidar data flown in leaf-off conditions for applications such as terrain mapping can effectively estimate forested riparian buffer H and FC within a range of riparian vegetation types. Results illustrate that: 1) leaf-off and leaf-on lidar percentile estimates are similar to measured heights in all plots except those dominated by deciduous compound-leaved trees where lidar underestimates H during leaf off periods; 2) canopy height models (CHMs) underestimate H by a larger margin compared to percentile methods and are influenced by vegetation type (conifer needle, deciduous simple leaf or deciduous compound leaf) and canopy height variability, 3) lidar estimates of FC are within 10% of plot measurements during leaf-on periods, but are underestimated during leaf-off periods except in mixed and conifer plots; and 4) depth of laser pulse penetration lower in the canopy is more variable compared to top of the canopy penetration which may influence within canopy vegetation structure estimates. This study demonstrates that leaf-off lidar data can be used to estimate forested riparian buffer canopy height within diverse vegetation conditions and fractional canopy cover within mixed and conifer forests when leaf-on lidar data are not available.

Influence of Vegetation Structure on Lidar-derived Canopy Height and Fractional Cover in Forested Riparian Buffers During Leaf-Off and Leaf-On Conditions

PubMed Central

Wasser, Leah; Day, Rick; Chasmer, Laura; Taylor, Alan

2013-01-01

Estimates of canopy height (H) and fractional canopy cover (FC) derived from lidar data collected during leaf-on and leaf-off conditions are compared with field measurements from 80 forested riparian buffer plots. The purpose is to determine if existing lidar data flown in leaf-off conditions for applications such as terrain mapping can effectively estimate forested riparian buffer H and FC within a range of riparian vegetation types. Results illustrate that: 1) leaf-off and leaf-on lidar percentile estimates are similar to measured heights in all plots except those dominated by deciduous compound-leaved trees where lidar underestimates H during leaf off periods; 2) canopy height models (CHMs) underestimate H by a larger margin compared to percentile methods and are influenced by vegetation type (conifer needle, deciduous simple leaf or deciduous compound leaf) and canopy height variability, 3) lidar estimates of FC are within 10% of plot measurements during leaf-on periods, but are underestimated during leaf-off periods except in mixed and conifer plots; and 4) depth of laser pulse penetration lower in the canopy is more variable compared to top of the canopy penetration which may influence within canopy vegetation structure estimates. This study demonstrates that leaf-off lidar data can be used to estimate forested riparian buffer canopy height within diverse vegetation conditions and fractional canopy cover within mixed and conifer forests when leaf-on lidar data are not available. PMID:23382966

Effect of bioparticle size on dispersion and retention in monolithic and perfusive beds

PubMed Central

Trilisky, Egor I.; Lenhoff, Abraham M.

2010-01-01

Single-component pulse response studies were used to compare the retention and transport behavior of small molecules, proteins, and a virus on commercially available monolithic and perfusive ion-exchangers. Temporal distortion and extra-column effects were corrected for using a simple algorithm based on the method of moments. It was found that temporal distortion is inversely related to the number of theoretical plates. With increasing bioparticle size, retention increased and the transition from a non-eluting to a non-adsorbing state with increasing ionic strength became more abrupt. Both of these observations are qualitatively explained by calculations of particle-surface electrostatic attractive energy. Calculations also show that, for sufficiently large bioparticles, such as viruses or cells, hydrodynamic drag can promote elution. Under non-adsorbing conditions, plate height increased only weakly with flow rate and the skew remained unchanged. With increasing retention, plate height increased dramatically for proteins. Plate height was scaled by permeability rather than bead diameter to enable comparison among different stationary phases. PMID:20951383

Verification results for the Spectral Ocean Wave Model (SOWM) by means of significant wave height measurements made by the GEOS-3 spacecraft

NASA Technical Reports Server (NTRS)

Pierson, W. J.; Salfi, R. E.

1978-01-01

Significant wave heights estimated from the shape of the return pulse wave form of the altimeter on GEOS-3 for forty-four orbit segments obtained during 1975 and 1976 are compared with the significant wave heights specified by the spectral ocean wave model (SOWM), which is the presently operational numerical wave forecasting model at the Fleet Numerical Weather Central. Except for a number of orbit segments with poor agreement and larger errors, the SOWM specifications tended to be biased from 0.5 to 1.0 meters too low and to have RMS errors of 1.0 to 1.4 meters. The much fewer larger errors can be attributed to poor wind data for some parts of the Northern Hemisphere oceans. The bias can be attributed to the somewhat too light winds used to generate the waves in the model. Other sources of error are identified in the equatorial and trade wind areas.

Femtosecond laser patterning of biological materials

NASA Astrophysics Data System (ADS)

Grigoropoulos, Costas P.; Jeon, Hojeong; Hidai, Hirofumi; Hwang, David J.

2011-03-01

This paper aims at presenting a review of work at the Laser Thermal Laboratory on the microscopic laser modification of biological materials using ultrafast laser pulses. We have devised a new method for fabricating high aspect ratio patterns of varying height by using two-photon polymerization process in order to study contact guidance and directed growth of biological cells. Studies using NIH-3T3 and MDCK cells indicate that cell morphology on fiber scaffolds is influenced by the pattern of actin microfilament bundles. Cells experienced different strength of contact guidance depending on the ridge height. Cell morphology and motility was investigated on micronscale anisotropic cross patterns and parallel line patterns having different aspect ratios. A significant effect on cell alignment and directionality of migration was observed. Cell morphology and motility were influenced by the aspect ratio of the cross pattern, the grid size, and the ridge height. Cell contractility was examined microscopically in order to measure contractile forces generated by individual cells on self-standing fiber scaffolds.

Growth Mode Transition in Complex Oxide Heteroepitaxy: Atomically Resolved Studies

DOE PAGES

Tselev, Alexander; Vasudevan, Rama K.; Gianfrancesco, Anthony G.; ...

2016-04-04

Here we performed investigations of the atomic-scale surface structure of epitaxial La 5/8Ca 3/8MnO 3 thin films as a model system dependent on growth conditions in pulsed laser deposition with emphasis on film growth kinetics. Postdeposition in situ scanning tunneling microscopy was combined with in operando reflective high-energy electron diffraction to monitor the film growth and ex situ X-ray diffraction for structural analysis. We find a correlation between the out-of-plane lattice parameter and both adspecies mobility and height of the Ehrlich–Schwoebel barrier, with mobility of adatoms greater over the cationically stoichiometric terminations. We find that the data suggest that themore » out-of-plane lattice parameter is dependent on the mechanism of epitaxial strain relaxation, which is controlled by the oxidative power of the deposition environment.« less

Nuclear Science Symposium, 21st, Scintillation and Semiconductor Counter Symposium, 14th, and Nuclear Power Systems Symposium, 6th, Washington, D.C., December 11-13, 1974, Proceedings

NASA Technical Reports Server (NTRS)

1975-01-01

Papers are presented dealing with latest advances in the design of scintillation counters, semiconductor radiation detectors, gas and position sensitive radiation detectors, and the application of these detectors in biomedicine, satellite instrumentation, and environmental and reactor instrumentation. Some of the topics covered include entopistic scintillators, neutron spectrometry by diamond detector for nuclear radiation, the spherical drift chamber for X-ray imaging applications, CdTe detectors in radioimmunoassay analysis, CAMAC and NIM systems in the space program, a closed loop threshold calibrator for pulse height discriminators, an oriented graphite X-ray diffraction telescope, design of a continuous digital-output environmental radon monitor, and the optimization of nanosecond fission ion chambers for reactor physics. Individual items are announced in this issue.

Response function of single crystal synthetic diamond detectors to 1-4 MeV neutrons for spectroscopy of D plasmas

NASA Astrophysics Data System (ADS)

Rebai, M.; Giacomelli, L.; Milocco, A.; Nocente, M.; Rigamonti, D.; Tardocchi, M.; Camera, F.; Cazzaniga, C.; Chen, Z. J.; Du, T. F.; Fan, T. S.; Giaz, A.; Hu, Z. M.; Marchi, T.; Peng, X. Y.; Gorini, G.

2016-11-01

A Single-crystal Diamond (SD) detector prototype was installed at Joint European Torus (JET) in 2013 and the achieved results have shown its spectroscopic capability of measuring 2.5 MeV neutrons from deuterium plasmas. This paper presents measurements of the SD response function to monoenergetic neutrons, which is a key point for the development of a neutron spectrometer based on SDs and compares them with Monte Carlo simulations. The analysis procedure allows for a good reconstruction of the experimental results. The good pulse height energy resolution (equivalent FWHM of 80 keV at 2.5 MeV), gain stability, insensitivity to magnetic field, and compact size make SDs attractive as compact neutron spectrometers of high flux deuterium plasmas, such as for instance those needed for the ITER neutron camera.

The torsional barriers of two equivalent methyl internal rotations in 2,5-dimethylfuran investigated by microwave spectroscopy

NASA Astrophysics Data System (ADS)

Van, Vinh; Bruckhuisen, Jonas; Stahl, Wolfgang; Ilyushin, Vadim; Nguyen, Ha Vinh Lam

2018-01-01

The microwave spectrum of 2,5-dimethylfuran was recorded using two pulsed molecular jet Fourier transform microwave spectrometers which cover the frequency range from 2 to 40 GHz. The internal rotations of two equivalent methyl tops with a barrier height of approximately 439.15 cm-1 introduce torsional splittings of all rotational transitions in the spectrum. For the spectral analysis, two different computer programs were applied and compared, the PAM-C2v-2tops code based on the principal axis method which treats several torsional states simultaneously, and the XIAM code based on the combined axis method, yielding accurate molecular parameters. The experimental work was supplemented by quantum chemical calculations. Two-dimensional potential energy surfaces depending on the torsional angles of both methyl groups were calculated and parametrized.

Laser-induced hydrodynamic instability and pattern formation in metallic nanofilms

NASA Astrophysics Data System (ADS)

Sureshkumar, R.; Trice, J.; Favazza, C.; Kalyanaraman, R.

2007-11-01

Cost effective methodologies for the robust generation of nanoscale patterns in thin films and at interfaces are crucial in photonic, opto-electronic and solar energy harvesting applications. When ultrathin metal films are exposed to a series of short (ns) laser pulses, spontaneous pattern formation results with spatio-temporal scales that depend on the film height and thermo-physical properties of the film/substrate bilayer. Various self-organization mechanisms have been identified, including a dewetting instability due to a competition between surface tension and dispersion forces, and intrinsic and/or extrinsic thermocapillary effects. We will discuss these mechanisms as well as the evolution of surface perturbations which have been explored using experiments, linear stability analysis and nonlinear dynamical simulations (Trice et al. Phys. Rev. B, 75, 235439 (2007); Favazza et al. Appl. Phys. Lett., 91, 043105 (2007); 88, 153118 (2006)).

Maple prepared organic heterostructures for photovoltaic applications

NASA Astrophysics Data System (ADS)

Stanculescu, A.; Socol, M.; Socol, G.; Mihailescu, I. N.; Girtan, M.; Stanculescu, F.

2011-09-01

In this study, we present the deposition of ZnPc, Alq3, and PTCDA thin films using Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. We also report the realisation of multilayer structures, made by the successive application of MAPLE. The films have been characterized by spectroscopic (UV-VIS and Photoluminescence) and microscopic (SEM and AFM) methods, and the effect of different deposition conditions such as fluence, number of pulses, and target concentration on the properties has been analysed. This paper also presents some investigations on the electrical conduction in sandwich type structures ITO or Si/organic layer/Au or Cu and ITO/double organic layer/Cu, emphasising the dominant effect of the height of the energetic barriers at the inorganic/organic and organic/organic interfaces.

The interaction with the lower ionosphere of electromagnetic pulses from lightning: Excitation of optical emissions

NASA Technical Reports Server (NTRS)

Taranenko, Y. N.; Inan, U. S.; Bell, T. F.

1993-01-01

A self consistent and fully kinetic simulation of the interaction of lightning radiated electromagnetic (EM) pulses with the nighttime lower ionosphere indicates that optical emissions observable with conventional instruments would be excited. For example, emissions of the 1st and 2nd positive bands of N2 occur at rates reaching 7 x 10(exp 7) and 10(exp 7) cu cm/s respectively at 92 km altitude for a lightning discharge with an electric field E(sub 100) = 20 V/m (normalized to a 100 km distance). The maximum height integrated intensities of these emissions are 4 x 10(exp 7) and 6 x 10(exp 6) R respectively, lasting for approx. 50 micrometers.

Superior local conductivity in self-organized nanodots on indium-tin-oxide films induced by femtosecond laser pulses.

PubMed

Wang, Chih; Wang, Hsuan-I; Tang, Wei-Tsung; Luo, Chih-Wei; Kobayashi, Takayoshi; Leu, Jihperng

2011-11-21

Large-area surface ripple structures of indium-tin-oxide films, composed of self-organized nanodots, were induced by femtosecond laser pulses, without scanning. The multi-periodic spacing (~800 nm, ~400 nm and ~200 nm) was observed in the laser-induced ripple of ITO films. The local conductivity of ITO films is significantly higher, by approximately 30 times, than that of the as-deposited ITO films, due to the formation of these nanodots. Such a significant change can be ascribed to the formation of indium metal-like clusters, which appear as budges of ~5 nm height, due to an effective volume increase after breaking the In-O to form In-In bonding. © 2011 Optical Society of America

Shape of intrinsic alpha pulse height spectra in lanthanide halide scintillators

NASA Astrophysics Data System (ADS)

Wolszczak, W.; Dorenbos, P.

2017-06-01

Internal contamination with actinium-227 and its daughters is a serious drawback in low-background applications of lanthanide-based scintillators. In this work we showed the important role of nuclear γ de-excitations on the shape of the internal alpha spectrum measured in scintillators. We calculated with Bateman equations the activities of contamination isotopes and the time evolution of actinium-227 and its progenies. Next, we measured the intrinsic background spectra of LaBr3(Ce), LaBr3(Ce,Sr) and CeBr3 with a digital spectroscopy technique, and we analyzed them with a pulse shape discrimination method (PSD) and a time-amplitude analysis. Finally, we simulated the α background spectrum with Geant4 tool-kit, consequently taking into account complex α-γ-electron events, the α / β ratio dependence on the α energy, and the electron/γ nonproportionality. We found that α-γ mixed events have higher light yield than expected for alpha particles alone, which leads to overestimation of the α / β ratio when it is measured with internal 227Th and 223Ra isotopes. The time-amplitude analysis showed that the α peaks of 219Rn and 215Po in LaBr3(Ce) and LaBr3(Ce,Sr) are not symmetric. We compared the simulation results with the measured data and provided further evidence of the important role of mixed α-γ-electron events for understanding the shape of the internal α spectrum in scintillators.

Global Monitoring of Clouds and Aerosols Using a Network of Micro-Pulse Lidar Systems

NASA Technical Reports Server (NTRS)

Welton, Ellsworth J.; Campbell, James R.; Spinhirne, James D.; Scott, V. Stanley

2000-01-01

Long-term global radiation programs, such as AERONET and BSRN, have shown success in monitoring column averaged cloud and aerosol optical properties. Little attention has been focused on global measurements of vertically resolved optical properties. Lidar systems are the preferred instrument for such measurements. However, global usage of lidar systems has not been achieved because of limits imposed by older systems that were large, expensive, and logistically difficult to use in the field. Small, eye-safe, and autonomous lidar systems are now currently available and overcome problems associated with older systems. The first such lidar to be developed is the Micro-pulse lidar System (MPL). The MPL has proven to be useful in the field because it can be automated, runs continuously (day and night), is eye-safe, can easily be transported and set up, and has a small field-of-view which removes multiple scattering concerns. We have developed successful protocols to operate and calibrate MPL systems. We have also developed a data analysis algorithm that produces data products such as cloud and aerosol layer heights, optical depths, extinction profiles, and the extinction-backscatter ratio. The algorithm minimizes the use of a priori assumptions and also produces error bars for all data products. Here we present an overview of our MPL protocols and data analysis techniques. We also discuss the ongoing construction of a global MPL network in conjunction with the AERONET program. Finally, we present some early results from the MPL network.

Relation between respiratory function and arterial stiffness assessed using brachial-ankle pulse wave velocity in healthy workers.

PubMed

Inomoto, Atsushi; Fukuda, Rika; Deguchi, Junko; Toyonaga, Toshihiro

2017-09-01

[Purpose] Current studies report that patients with chronic obstructive pulmonary disease (COPD) may also have arteriosclerosis. This study aimed to investigate the relationship between respiratory function and arterial stiffness in healthy workers using the brachial-ankle pulse wave velocity (baPWV). [Subjects and Methods] This study included 104 male Japanese workers without COPD. We collected participant information and measured hemodynamics, body composition, and respiratory function. [Results] In the correlation analysis, baPWV showed a significant positive correlation with age, smoking index, systolic blood pressure, diastolic blood pressure, and heart rate, and a significant negative correlation with height, fat free mass, lower limb muscle mass, forced vital capacity (FVC), and forced expiratory volume in one second (FEV1). In multiple regression analysis using factors other than baPWV and respiratory function as adjustment variables, both FVC and FEV1 showed a significant negative relationship with baPWV (p=0.009 and p=0.027, respectively). FEV1/FVC was not significantly related to baPWV (p=0.704). [Conclusion] The results of this study indicated that FEV1/FVC and the proportion of FEV1 predicted, which are indicators of airflow limitation, are not predictors of baPWV in workers without airflow limitation. However, since baPWV showed a significant negative relationship with FVC and FEV 1, the reduction in respiratory function that does not cause airflow limitation, such as FVC or FEV1 decline, may be related to an increase in the risk of arterial stiffness.

Calibration of large area Micromegas detectors using cosmic rays

NASA Astrophysics Data System (ADS)

Biebel, O.; Flierl, B.; Herrmann, M.; Hertenberger, R.; Klitzner, F.; Lösel, P.; Müller, R.; Valderanis, C.; Zibell, A.

2017-06-01

Currently m2-sized micropattern detectors with spatial resolution better than 100 μm and online trigger capability are of big interest for many experiments. Large size in combination with superb spatial resolution and trigger capability implicates that the construction of these detectors is highly sophisticated and imposes strict mechanical tolerances. We developed a method to survey assembled and working detectors on potential deviations of the micro pattern readout structures from design value as well as deformations of the whole detector, using cosmic muons in a tracking facility. The LMU Cosmic Ray Facility consists of two 8 m2 ATLAS Monitored Drift Tube chambers (MDT) for precision muon reference tracking and two segmented trigger hodoscopes with sub-ns time-resolution and additional 10 cm position information along the wires of the MDTs. It provides information on homogeneity in efficiency and pulse height of one or several micropattern detectors installed in between the MDTs. With an angular acceptance of -30° to +30° the comparison of the reference muon tracking with centroidal position determination or time projection chamber like track reconstruction in the micropattern detector allows for calibration in three dimensions. We present results of a m2-sized one-dimensional resistive strip Micromegas detector consisting of two readout boards with in total 2048 strips, read out by 16 APV25 front-end boards. This 16-fold segmentation along the precision direction in combination with a 10-fold segmentation in orthogonal direction by the resolution of the trigger hodoscope, allows for very detailed analysis of the 1 m2 detector under study by subdivision into 160 partitions, each being analyzed separately. We are able to disentangle deviations from the readout strip straightness and global deformation due to the small overpressure caused by the Ar:CO2 (93:7) gas mixture flux. We introduce the alignment and calibration procedure, report on homogeneity in efficiency and pulse height and present results on deformation and performance of the m2-sized Micromegas.

A new approach to large area microchannel plate manufacture

NASA Technical Reports Server (NTRS)

1986-01-01

Methods of manufacture of twisted single elements as the base for producing microchannel plates (MCP) are discussed. Initial evaluations validated the off-axis channel concept and no technological roadblocks were identified which would prevent fabrication of high gain, high spatial resolution, large format MCP's using this technique. The first MP's have operated at stable gains of 3 million with pulse height resolution superior to results obtained by standard chevron MCP's.

Noise reduction and control in mode-locked semiconductor diode lasers for use in next-generation all-optical analog-to-digital converters

NASA Astrophysics Data System (ADS)

DePriest, Christopher M.; Abeles, Joseph H.; Braun, Alan; Delfyett, Peter J., Jr.

2000-07-01

External-cavity, actively-modelocked semiconductor diode lasers (SDLs) have proven to be attractive candidates for forming the backbone of next-generation analog-to-digital converters (ADCs), which are currently being developed to sample signals at repetition rates exceeding several GHz with up to 12 bits of digital resolution. Modelocked SDLs are capable of producing waveform-sampling pulse trains with very low temporal jitter (phase noise) and very small fluctuations in pulse height (amplitude noise)--two basic conditions that must be met in order for high-speed ADCs to achieve projected design goals. Single-wavelength modelocked operation (at nominal repetition frequencies of 400 MHz) has produced pulse trains with very low amplitude noise (approximately 0.08%), and the implementation of a phase- locked-loop has been effective in reducing the system's low- frequency phase noise (RMS timing jitter for offset frequencies between 10 Hz and 10 kHz has been reduced from 240 fs to 27 fs).

A short-pulse mode for the SPHINX LTD Z-pinch driver

NASA Astrophysics Data System (ADS)

D'Almeida, Thierry; Lassalle, Francis; Zucchini, Frederic; Loyen, Arnaud; Morell, Alain; Chuvatin, Alexander

2015-11-01

The SPHINX machine is a 6MA, 1 μs, LTD Z-pinch driver at CEA Gramat (France) and primarily used for studying radiation effects. Different power amplification concepts were examined in order to reduce the current rise time without modifying the generator discharge scheme, including the Dynamic Load Current Multiplier (DLCM) proposed by Chuvatin. A DLCM device, capable of shaping the current pulse without reducing the rise time, was developed at CEA. This device proved valuable for isentropic compression experiments in cylindrical geometry. Recently, we achieved a short pulse operation mode by inserting a vacuum closing switch between the DLCM and the load. The current rise time was reduced to ~300 ns. We explored the use of a reduced-height wire array for the Dynamic Flux Extruder in order to improve the wire array compression rate and increase the efficiency of the current transfer to the load. These developments are presented. Potential benefits of these developments for future Z pinch experiments are discussed.

Correcting X-ray spectra obtained from the AXAF VETA-I mirror calibration for pileup, continuum, background and deadtime

NASA Technical Reports Server (NTRS)

Chartas, G.; Flanagan, K.; Hughes, J. P.; Kellogg, E. M.; Nguyen, D.; Zombek, M.; Joy, M.; Kolodziejezak, J.

1993-01-01

The VETA-I mirror was calibrated with the use of a collimated soft X-ray source produced by electron bombardment of various anode materials. The FWHM, effective area and encircled energy were measured with the use of proportional counters that were scanned with a set of circular apertures. The pulsers from the proportional counters were sent through a multichannel analyzer that produced a pulse height spectrum. In order to characterize the properties of the mirror at different discrete photon energies one desires to extract from the pulse height distribution only those photons that originated from the characteristic line emission of the X-ray target source. We have developed a code that fits a modeled spectrum to the observed X-ray data, extracts the counts that originated from the line emission, and estimates the error in these counts. The function that is fitted to the X-ray spectra includes a Prescott function for the resolution of the detector a second Prescott function for a pileup peak and a X-ray continuum function. The continuum component is determined by calculating the absorption of the target Bremsstrahlung through various filters, correcting for the reflectivity of the mirror and convolving with the detector response.

Correcting x ray spectra obtained from the AXAF VETA-I mirror calibration for pileup, continuum, background and deadtime

NASA Technical Reports Server (NTRS)

Chartas, G.; Flanagan, Kathy; Hughes, John P.; Kellogg, Edwin M.; Nguyen, D.; Zombeck, M.; Joy, M.; Kolodziejezak, J.

1992-01-01

The VETA-I mirror was calibrated with the use of a collimated soft X-ray source produced by electron bombardment of various anode materials. The FWHM, effective area and encircled energy were measured with the use of proportional counters that were scanned with a set of circular apertures. The pulsers from the proportional counters were sent through a multichannel analyzer that produced a pulse height spectrum. In order to characterize the properties of the mirror at different discrete photon energies one desires to extract from the pulse height distribution only those photons that originated from the characteristic line emission of the X-ray target source. We have developed a code that fits a modeled spectrum to the observed X-ray data, extracts the counts that originated from the line emission, and estimates the error in these counts. The function that is fitted to the X-ray spectra includes a Prescott function for the resolution of the detector a second Prescott function for a pileup peak and a X-ray continuum function. The continuum component is determined by calculating the absorption of the target Bremsstrahlung through various filters correcting for the reflectivity of the mirror and convolving with the detector response.

Measuring Geophysical Parameters of the Greenland Ice Sheet using Airborne Radar Altimetry

NASA Technical Reports Server (NTRS)

Ferraro, Ellen J.; Swift. Calvin T.

1995-01-01

This paper presents radar-altimeter scattering models for each of the diagenetic zones of the Greenland ice sheet. AAFE radar- altimeter waveforms obtained during the 1991 and 1993 NASA multi-sensor airborne altimetry experiments over Greenland reveal that the Ku-band return pulse changes significantly with the different diagenetic zones. These changes are due to varying amounts of surface and volume scattering in the return waveform. In the ablation and soaked zones, where surface scattering dominates the AAFE return, geophysical parameters such as rms surface height and rms surface slope are obtained by fitting the waveforms to a surface-scattering model. Waveforms from the percolation zone show that the sub-surface ice features have a much more significant effect on the return pulse than the surrounding snowpack. Model percolation waveforms, created using a combined surface- and volume-scattering model and an ice-feature distribution obtained during the 1993 field season, agree well with actual AAFE waveforms taken in the same time period. Using a combined surface- and volume-scattering model for the dry-snow-zone return waveforms, the rms surface height and slope and the attenuation coefficient of the snowpack are obtained. These scattering models not only allow geophysical parameters of the ice sheet to be measured but also help in the understanding of satellite radar-altimeter data.

Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited)

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

Cooper, C. M., E-mail: coopercm@fusion.gat.com; Pace, D. C.; Paz-Soldan, C.

2016-11-15

A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5–100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead “pinhole camera” mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20 000 pulses permore » second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.« less

Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited)

NASA Astrophysics Data System (ADS)

Cooper, C. M.; Pace, D. C.; Paz-Soldan, C.; Commaux, N.; Eidietis, N. W.; Hollmann, E. M.; Shiraki, D.

2016-11-01

A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20 000 pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.

Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited).

PubMed

Cooper, C M; Pace, D C; Paz-Soldan, C; Commaux, N; Eidietis, N W; Hollmann, E M; Shiraki, D

2016-11-01

A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20 000 pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.

Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited)

DOE PAGES

Cooper, C. M.; Pace, D. C.; Paz-Soldan, C.; ...

2016-08-30

A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20,000 pulses permore » second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Furthermore, magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.« less

[Effect of blood lipid on the change of brachial-ankle pulse wave velocity among prehypertensive population].

PubMed

Wang, Lin; Shuai, Ping; Liu, Yuping; Cheng, Youfu; Yang, Hua; Li, Tingxin; Gong, Lirong; Ren, Jiaojiao; Wang, Hongjia

2014-09-01

To explore the effect of blood lipid and lipoprotein ratios on the change of brachial-ankle pulse wave velocity (baPWV) among prehypertensive subjects. 11 611 subjects with normal blood pressure (BP) were divided into two groups, which was one with optimal blood pressure (BP<120/80 mmHg) and the other with prehypertension (BP:120-139/80-89 mmHg). Height, weight, baPWV, fasting blood-glucose, TC, TG, LDL-C and HDL-C were detected. The abnormal rate of baPWV in prehypertension group was obviously higher than that in the optimal blood pressure group. For optimal blood pressure group, the abnormality of TG, TC, LDL-C, TC/HDL-C as well as LDL-C/HDL-C, caused the increase of baPWV significantly (P < 0.001). For prehypertensive group, the abnormality of TC and LDL-C caused the significant increase of baPWV (P < 0.001). Results from logistic regression analysis showed that except for age, BMI and fasting blood-glucose, TC/HDL-C increasing was the independent risk factor in optimal blood pressure group, while TG increasing was for the prehypertension group. With different normal BP level, both abnormality of blood lipid and lipoprotein ratio were the independent risk factors for baPWV increasing.

ALART: a novel lidar system for vegetation height retrieval from space

NASA Astrophysics Data System (ADS)

Foglia Manzillo, P.; van Dijk, C. N.; Conticello, S.; Esposito, M.; Lussana, R.; Villa, F.; Tamborini, D.; Zappa, F.; Tosi, A.; Roncat, A.; Pfeiffer, N.; Entner, T.; Lampridis, D.

2015-10-01

We propose a multi-kHz Single-Photon Counting (SPC) space LIDAR, exploiting low energy pulses with high repetition frequency (PRF). The high PRF allows one to overcome the low signal limitations, as many return shots can be collected from nearly the same scattering area. The ALART space instrument exhibits a multi-beam design, providing height retrieval over a wide area and terrain slope measurements. This novel technique, working with low SNRs, allows multiple beam generation with a single laser, limiting mass and power consumption. As the receiver has a certain probability to detect multiple photons from different levels of canopy, a histogram is constructed and used to retrieve the properties of the target tree, by means of a modal decomposition of the reconstructed waveform. A field demonstrator of the ALART space instrument is currently being developed by a European consortium led by cosine | measurement systems and funded by ESA under the TRP program. The demonstrator requirements have been derived to be representative of the target instrument and it will be tested in an equipped tower in woodland areas in the Netherlands. The employed detectors are state-of-the-art CMOS Single-Photon Avalanche Diode (SPAD) matrices with 1024 pixels. Each pixel is independently equipped with an integrated Time-to-Digital Converter (TDC), achieving a timing accuracy that is much lower than the SPAD dead time, resulting in a distance resolution in the centimeter range. The instrument emits nanosecond laser pulses with energy on the order of several μJ, at a PRF of ~ 10 kHz, and projects on ground a three-beams pattern. An extensive field measurement campaign will validate the employed technologies and algorithms for vegetation height retrieval.

Pulse Jet Mixing Tests With Noncohesive Solids

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

Meyer, Perry A.; Bamberger, Judith A.; Enderlin, Carl W.

2012-02-17

This report summarizes results from pulse jet mixing (PJM) tests with noncohesive solids in Newtonian liquid. The tests were conducted during FY 2007 and 2008 to support the design of mixing systems for the Hanford Waste Treatment and Immobilization Plant (WTP). Tests were conducted at three geometric scales using noncohesive simulants, and the test data were used to develop models predicting two measures of mixing performance for full-scale WTP vessels. The models predict the cloud height (the height to which solids will be lifted by the PJM action) and the critical suspension velocity (the minimum velocity needed to ensure allmore » solids are suspended off the floor, though not fully mixed). From the cloud height, the concentration of solids at the pump inlet can be estimated. The predicted critical suspension velocity for lifting all solids is not precisely the same as the mixing requirement for 'disturbing' a sufficient volume of solids, but the values will be similar and closely related. These predictive models were successfully benchmarked against larger scale tests and compared well with results from computational fluid dynamics simulations. The application of the models to assess mixing in WTP vessels is illustrated in examples for 13 distinct designs and selected operational conditions. The values selected for these examples are not final; thus, the estimates of performance should not be interpreted as final conclusions of design adequacy or inadequacy. However, this work does reveal that several vessels may require adjustments to design, operating features, or waste feed properties to ensure confidence in operation. The models described in this report will prove to be valuable engineering tools to evaluate options as designs are finalized for the WTP. Revision 1 refines data sets used for model development and summarizes models developed since the completion of Revision 0.« less

Multibeam Laser Altimeter for Planetary Topographic Mapping

NASA Technical Reports Server (NTRS)

Garvin, J. B.; Bufton, J. L.; Harding, D. J.

1993-01-01

Laser altimetry provides an active, high-resolution, high-accuracy method for measurement of planetary and asteroid surface topography. The basis of the measurement is the timing of the roundtrip propagation of short-duration pulses of laser radiation between a spacecraft and the surface. Vertical, or elevation, resolution of the altimetry measurement is determined primarily by laser pulse width, surface-induced spreading in time of the reflected pulse, and the timing precision of the altimeter electronics. With conventional gain-switched pulses from solid-state lasers and nanosecond resolution timing electronics, submeter vertical range resolution is possible anywhere from orbital altitudes of approximately 1 km to altitudes of several hundred kilometers. Horizontal resolution is a function of laser beam footprint size at the surface and the spacing between successive laser pulses. Laser divergence angle and altimeter platform height above the surface determine the laser footprint size at the surface, while laser pulse repetition rate, laser transmitter beam configuration, and altimeter platform velocity determine the spacing between successive laser pulses. Multiple laser transmitters in a single laser altimeter instrument that is orbiting above a planetary or asteroid surface could provide across-track as well as along-track coverage that can be used to construct a range image (i.e., topographic map) of the surface. We are developing a pushbroom laser altimeter instrument concept that utilizes a linear array of laser transmitters to provide contiguous across-track and along-track data. The laser technology is based on the emerging monolithic combination of individual, 1-sq cm diode-pumped Nd:YAG laser pulse emitters. Details of the multi-emitter laser transmitter technology, the instrument configuration, and performance calculations for a realistic Discovery-class mission will be presented.

Relative effects of posture and activity on human height estimation from surveillance footage.

PubMed

Ramstrand, Nerrolyn; Ramstrand, Simon; Brolund, Per; Norell, Kristin; Bergström, Peter

2011-10-10

Height estimations based on security camera footage are often requested by law enforcement authorities. While valid and reliable techniques have been established to determine vertical distances from video frames, there is a discrepancy between a person's true static height and their height as measured when assuming different postures or when in motion (e.g., walking). The aim of the research presented in this report was to accurately record the height of subjects as they performed a variety of activities typically observed in security camera footage and compare results to height recorded using a standard height measuring device. Forty-six able bodied adults participated in this study and were recorded using a 3D motion analysis system while performing eight different tasks. Height measurements captured using the 3D motion analysis system were compared to static height measurements in order to determine relative differences. It is anticipated that results presented in this report can be used by forensic image analysis experts as a basis for correcting height estimations of people captured on surveillance footage. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Measurement of Aortic Pulse Wave Velocity With a Connected Bathroom Scale.

PubMed

Campo, David; Khettab, Hakim; Yu, Roger; Genain, Nicolas; Edouard, Paul; Buard, Nadine; Boutouyrie, Pierre

2017-09-01

Measurement of arterial stiffness should be more available. Our aim was to show that aortic pulse wave velocity can be reliably measured with a bathroom scale combining the principles of ballistocardiography (BCG) and impedance plethysmography on a single foot. The calibration of the bathroom scale was conducted on a group of 106 individuals. The aortic pulse wave velocity was measured with the SphygmoCor in the supine position. Three consecutive measurements were then performed on the Withings scale in the standing position. This aorta-leg pulse transit time (alPTT) was then converted into a velocity with the additional input of the height of the person. Agreement between the SphygmoCor and the bathroom scale so calibrated is assessed on a separate group of 86 individuals, following the same protocol. The bias is 0.25 m·s-1 and the SE 1.39 m·s-1. This agreement with Sphygmocor is "acceptable" according to the ARTERY classification. The alPTT correlated well with cfPTT with (Spearman) R = 0.73 in pooled population (cal 0.79, val 0.66). The aorta-leg pulse wave velocity correlated with carotid-femoral pulse wave velocity with R = 0.76 (cal 0.80, val 0.70). Estimation of the aortic pulse wave velocity is feasible with a bathroom scale. Further investigations are needed to improve the repeatability of measurements and to test their accuracy in different populations and conditions. © The Author 2017. Published by Oxford University Press on behalf of American Journal of Hypertension.

Formation of Size- and Position-Controlled Nanometer Size Pt Dots on GaAs and InP Substrates by Pulsed Electrochemical Deposition

NASA Astrophysics Data System (ADS)

Sato, Taketomo; Kaneshiro, Chinami; HiroshiOkada, HiroshiOkada; Hasegawa, Hideki

1999-04-01

Attempts were made to form regular arrays of size- andposition-controlled Pt-dots on GaAs and InP by combining an insitu electrochemical process with the electron beam (EB)lithography. This utilizes the precipitation of Pt nano-particles atthe initial stage of electrodeposition. First, electrochemicalconditions were optimized in the mode of self-assembled dot arrayformation on unpatterned substrates. Minimum in-plane dot diameters of22 nm and 26 nm on GaAs and InP, respectively, were obtained underthe optimal pulsed mode. Then, Pt dots were selectively formed onpatterned substrates with open circular windows formed by EBlithography, thereby realizing dot-position control. The Pt dot wasfound to have been deposited at the center of each open window, andthe in-plane diameter of the dot could be controlled by the number,width and period of the pulse-waveform applied to substrates. Aminimum diameter of 20 nm was realized in windows with a diameter of100 nm, using a single pulse. Current-voltage (I-V)measurements using an atomic force microscopy (AFM) system with aconductive probe indicated that each Pt dot/n-GaAs contact possessed ahigh Schottky barrier height of about 1 eV.

Pulse analysis of acoustic emission signals

NASA Technical Reports Server (NTRS)

Houghton, J. R.; Packman, P. F.

1977-01-01

A method for the signature analysis of pulses in the frequency domain and the time domain is presented. Fourier spectrum, Fourier transfer function, shock spectrum and shock spectrum ratio were examined in the frequency domain analysis and pulse shape deconvolution was developed for use in the time domain analysis. Comparisons of the relative performance of each analysis technique are made for the characterization of acoustic emission pulses recorded by a measuring system. To demonstrate the relative sensitivity of each of the methods to small changes in the pulse shape, signatures of computer modeled systems with analytical pulses are presented. Optimization techniques are developed and used to indicate the best design parameter values for deconvolution of the pulse shape. Several experiments are presented that test the pulse signature analysis methods on different acoustic emission sources. These include acoustic emission associated with (a) crack propagation, (b) ball dropping on a plate, (c) spark discharge, and (d) defective and good ball bearings. Deconvolution of the first few micro-seconds of the pulse train is shown to be the region in which the significant signatures of the acoustic emission event are to be found.

Pulse analysis of acoustic emission signals

NASA Technical Reports Server (NTRS)

Houghton, J. R.; Packman, P. F.

1977-01-01

A method for the signature analysis of pulses in the frequency domain and the time domain is presented. Fourier spectrum, Fourier transfer function, shock spectrum and shock spectrum ratio were examined in the frequency domain analysis, and pulse shape deconvolution was developed for use in the time domain analysis. Comparisons of the relative performance of each analysis technique are made for the characterization of acoustic emission pulses recorded by a measuring system. To demonstrate the relative sensitivity of each of the methods to small changes in the pulse shape, signatures of computer modeled systems with analytical pulses are presented. Optimization techniques are developed and used to indicate the best design parameters values for deconvolution of the pulse shape. Several experiments are presented that test the pulse signature analysis methods on different acoustic emission sources. These include acoustic emissions associated with: (1) crack propagation, (2) ball dropping on a plate, (3) spark discharge and (4) defective and good ball bearings. Deconvolution of the first few micro-seconds of the pulse train are shown to be the region in which the significant signatures of the acoustic emission event are to be found.

Nonlinear interactions of electromagnetic waves with the auroral ionosphere

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

Wong, Alfred Y.

1999-09-20

The ionosphere provides us with an opportunity to perform plasma experiments in an environment with long confinement times, very large-scale lengths, and no confining walls. The auroral ionosphere with its nearly vertical magnetic field geometry is uniquely endowed with large amount of free energy from electron and ion precipitation along the magnetic field and mega-ampere current across the magnetic field. To take advantage of this giant outdoor laboratory, two facilities HAARP and HIPAS, with frequencies ranging from the radio to optical bands, are now available for active probing of and interaction with this interesting region. The ponderomotive pressures from themore » self-consistent wave fields have produced significant local perturbations of density and particle distributions at heights where the incident EM frequency matches a plasma resonance. This paper will review theory and experiments covering the nonlinear phenomena of parametric decay instability to wave collapse processes. At HF frequencies plasma lenses can be created by preconditioning pulses to focus what is a normally divergent beam into a high-intensity spot to further enhance nonlinear phenomena. At optical wavelengths a large rotating liquid metal mirror is used to focus laser pulses up to a given height. Such laser pulses are tuned to the same wavelengths of selected atomic and molecular resonances, with resulting large scattering cross sections. Ongoing experiments on dual-site experiments and excitation of ELF waves will be presented. The connection of such basic studies to environmental applications will be discussed. Such applications include the global communication using ELF waves, the ozone depletion and remediation and the control of atmospheric CO{sub 2} through the use of ion cyclotron resonant heating.« less

Nonlinear interactions of electromagnetic waves with the auroral ionosphere

NASA Astrophysics Data System (ADS)

Wong, Alfred Y.

1999-09-01

The ionosphere provides us with an opportunity to perform plasma experiments in an environment with long confinement times, very large-scale lengths, and no confining walls. The auroral ionosphere with its nearly vertical magnetic field geometry is uniquely endowed with large amount of free energy from electron and ion precipitation along the magnetic field and mega-ampere current across the magnetic field. To take advantage of this giant outdoor laboratory, two facilities HAARP and HIPAS, with frequencies ranging from the radio to optical bands, are now available for active probing of and interaction with this interesting region. The ponderomotive pressures from the self-consistent wave fields have produced significant local perturbations of density and particle distributions at heights where the incident EM frequency matches a plasma resonance. This paper will review theory and experiments covering the nonlinear phenomena of parametric decay instability to wave collapse processes. At HF frequencies plasma lenses can be created by preconditioning pulses to focus what is a normally divergent beam into a high-intensity spot to further enhance nonlinear phenomena. At optical wavelengths a large rotating liquid metal mirror is used to focus laser pulses up to a given height. Such laser pulses are tuned to the same wavelengths of selected atomic and molecular resonances, with resulting large scattering cross sections. Ongoing experiments on dual-site experiments and excitation of ELF waves will be presented. The connection of such basic studies to environmental applications will be discussed. Such applications include the global communication using ELF waves, the ozone depletion and remediation and the control of atmospheric CO2 through the use of ion cyclotron resonant heating.

Demonstration and Optimization of BNFL's Pulsed Jet Mixing and RFD Sampling Systems Using NCAW Simulant

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

JR Bontha; GR Golcar; N Hannigan

2000-08-29

The BNFL Inc. flowsheet for the pretreatment and vitrification of the Hanford High Level Tank waste includes the use of several hundred Reverse Flow Diverters (RFDs) for sampling and transferring the radioactive slurries and Pulsed Jet mixers to homogenize or suspend the tank contents. The Pulsed Jet mixing and the RFD sampling devices represent very simple and efficient methods to mix and sample slurries, respectively, using compressed air to achieve the desired operation. The equipment has no moving parts, which makes them very suitable for mixing and sampling highly radioactive wastes. However, the effectiveness of the mixing and sampling systemsmore » are yet to be demonstrated when dealing with Hanford slurries, which exhibit a wide range of physical and theological properties. This report describes the results of the testing of BNFL's Pulsed Jet mixing and RFD sampling systems in a 13-ft ID and 15-ft height dish-bottomed tank at Battelle's 336 building high-bay facility using AZ-101/102 simulants containing up to 36-wt% insoluble solids. The specific objectives of the work were to: Demonstrate the effectiveness of the Pulsed Jet mixing system to thoroughly homogenize Hanford-type slurries over a range of solids loading; Minimize/optimize air usage by changing sequencing of the Pulsed Jet mixers or by altering cycle times; and Demonstrate that the RFD sampler can obtain representative samples of the slurry up to the maximum RPP-WTP baseline concentration of 25-wt%.« less

Processing parameter optimization for the laser dressing of bronze-bonded diamond wheels

NASA Astrophysics Data System (ADS)

Deng, H.; Chen, G. Y.; Zhou, C.; Li, S. C.; Zhang, M. J.

2014-01-01

In this paper, a pulsed fiber-laser dressing method for bronze-bonded diamond wheels was studied systematically and comprehensively. The mechanisms for the laser dressing of bronze-bonded diamond wheels were theoretically analyzed, and the key processing parameters that determine the results of laser dressing, including the laser power density, pulse overlap ratio, ablation track line overlap ratio, and number of scanning cycles, were proposed for the first time. Further, the effects of these four key parameters on the oxidation-damaged layer of the material surface, the material removal efficiency, the material surface roughness, and the average protrusion height of the diamond grains were explored and summarized through pulsed laser ablation experiments. Under the current experimental conditions, the ideal values of the laser power density, pulse overlap ratio, ablation track line overlap ratio, and number of scanning cycles were determined to be 4.2 × 107 W/cm2, 30%, 30%, and 16, respectively. Pulsed laser dressing experiments were conducted on bronze-bonded diamond wheels using the optimized processing parameters; next, both the normal and tangential grinding forces produced by the dressed grinding wheel were measured while grinding alumina ceramic materials. The results revealed that the normal and tangential grinding forces produced by the laser-dressed grinding wheel during grinding were smaller than those of grinding wheels dressed using the conventional mechanical method, indicating that the pulsed laser dressing technology provides irreplaceable advantages relative to the conventional mechanical dressing method.

Performance evaluation for 120 four-layer DOI block detectors of the jPET-D4.

PubMed

Inadama, Naoko; Murayama, Hideo; Ono, Yusuke; Tsuda, Tomoaki; Hamamoto, Manabu; Yamaya, Taiga; Yoshida, Eiji; Shibuya, Kengo; Nishikido, Fumihiko; Takahashi, Kei; Kawai, Hideyuki

2008-01-01

The jPET-D4 is a brain positron emission tomography (PET) scanner that we have developed to meet user demands for high sensitivity and high spatial resolution. For this scanner, we developed a four-layer depth-of-interaction (DOI) detector. The four-layer DOI detector is a key component for the jPET-D4, its performance has great influence on the overall system performance. Previously, we reported the original technique for encoding four-layer DOI. Here, we introduce the final design of the jPET-D4 detector and present the results of an investigation on uniformity in performance of the detector. The performance evaluation was done over the 120 DOI crystal blocks for the detectors, which are to be assembled into the jPET-D4 scanner. We also introduce the crystal assembly method, which is simple enough, even though each DOI crystal block is composed of 1,024 crystal elements. The jPET-D4 detector consists of four layers of 16 x 16 Gd(2)SiO(5) (GSO) crystals and a 256-channel flat-panel position-sensitive photomultiplier tube (256ch FP-PMT). To identify scintillated crystals in the four-layer DOI detector, we use pulse shape discrimination and position discrimination on the two-dimensional (2D) position histogram. For pulse shape discrimination, two kinds of GSO crystals that show different scintillation decay time constants are used in the upper two and lower two layers, respectively. Proper reflector arrangement in the crystal block then allows the scintillated crystals to be identified in these two-layer groupings with two 2D position histograms. We produced the 120 DOI crystal blocks for the jPET-D4 system, and measured their characteristics such as the accuracy of pulse shape discrimination, energy resolution, and the pulse height of the full energy peak. The results show a satisfactory and uniform performance of the four-layer DOI crystal blocks; for example, misidentification rate in each GSO layer is <5% based on pulse shape discrimination, the averaged energy resolutions for the central four crystals of the first (farthest from the FP-PMT), second, third, and 4th layers are 15.7 +/- 1.0, 15.8 +/- 0.6, 17.7 +/- 1.2, and 17.3 +/- 1.4%, respectively, and variation in pulse height of the full energy peak among the four layers is <5% on average.

High-frequency pulsed low-level diode laser therapy accelerates wound healing of tooth extraction socket: An in vivo study.

PubMed

Noda, Masahiro; Aoki, Akira; Mizutani, Koji; Lin, Taichen; Komaki, Motohiro; Shibata, Shunichi; Izumi, Yuichi

2016-12-01

This study aimed to evaluate the effects of high-frequency pulsed (HiFP) low-level laser therapy (LLLT) on early wound healing of tooth extraction sockets in rats. Bilateral maxillary first molars were extracted from 6-week-old Sprague-Dawley rats. Sockets on the right were treated by HiFP low-level diode laser irradiation (904-910 nm); the left sides served as unirradiated controls. LLLT (0.28 W, 30 kHz, 200-ns pulse, 0.6% duty cycle, 61.2 J/cm 2 total power density) was employed immediately after extraction and every 24 hours thereafter. The maxillae including the sockets were resected 3 or 7 days after extraction. Soft-tissue healing was evaluated on days 0, 3, and 7. The bone mineral content (BMC), bone volume (BV), and bone mineral density (BMD) of the extraction sockets were evaluated by microcomputed tomography, and histomorphometric analysis was carried out on day 7. Real-time PCR analysis of osteogenic marker expression and immunohistochemical detection of proliferating cell nuclear antigen (PCNA)-positive cells were performed on day 3. Compared with control sites, the un-epithelialized areas of the extracted sites were significantly reduced by irradiation (P = 0.04), and the BMC, BV, and BMD of laser-treated sites were significantly increased (P = 0.004, 0.006, and 0.009, respectively). On day 7, the mean height of newly formed immature woven bone was higher in laser-treated sites (P = 0.24). On day 3, laser-treated sites showed significantly higher osteocalcin mRNA expression (P = 0.04) and PCNA-positive cell numbers (P = 0.01). HiFP low-level diode laser irradiation enhanced soft- and hard-tissue healing of tooth extraction sockets. Lasers Surg. Med. 48:955-964, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Associations between height and blood pressure in the United States population

PubMed Central

Bourgeois, Brianna; Watts, Krista; Thomas, Diana M.; Carmichael, Owen; Hu, Frank B.; Heo, Moonseong; Hall, John E.; Heymsfield, Steven B.

2017-01-01

Abstract The mechanisms linking short stature with an increase in cardiovascular and cerebrovascular disease risk remain elusive. This study tested the hypothesis that significant associations are present between height and blood pressure in a representative sample of the US adult population. Participants were 12,988 men and women from a multiethnic sample (age ≥ 18 years) evaluated in the 1999 to 2006 National Health and Nutrition Examination Survey who were not taking antihypertensive medications and who had complete height, weight, % body fat, and systolic and diastolic arterial blood pressure (SBP and DBP) measurements; mean arterial blood pressure and pulse pressure (MBP and PP) were calculated. Multiple regression models for men and women were developed with each blood pressure as dependent variable and height, age, race/ethnicity, body mass index, % body fat, socioeconomic status, activity level, and smoking history as potential independent variables. Greater height was associated with significantly lower SBP and PP, and higher DBP (all P < .001) in combined race/ethnic–sex group models beginning in the 4th decade. Predicted blood pressure differences between people who are short and tall increased thereafter with greater age except for MBP. Socioeconomic status, activity level, and smoking history did not consistently contribute to blood pressure prediction models. Height-associated blood pressure effects were present in US adults who appeared in the 4th decade and increased in magnitude with greater age thereafter. These observations, in the largest and most diverse population sample evaluated to date, provide support for postulated mechanisms linking adult stature with cardiovascular and cerebrovascular disease risk. PMID:29390353

A Novel Mobile Phone Application for Pulse Pressure Variation Monitoring Based on Feature Extraction Technology: A Method Comparison Study in a Simulated Environment.

PubMed

Desebbe, Olivier; Joosten, Alexandre; Suehiro, Koichi; Lahham, Sari; Essiet, Mfonobong; Rinehart, Joseph; Cannesson, Maxime

2016-07-01

Pulse pressure variation (PPV) can be used to assess fluid status in the operating room. This measurement, however, is time consuming when done manually and unreliable through visual assessment. Moreover, its continuous monitoring requires the use of expensive devices. Capstesia™ is a novel Android™/iOS™ application, which calculates PPV from a digital picture of the arterial pressure waveform obtained from any monitor. The application identifies the peaks and troughs of the arterial curve, determines maximum and minimum pulse pressures, and computes PPV. In this study, we compared the accuracy of PPV generated with the smartphone application Capstesia (PPVapp) against the reference method that is the manual determination of PPV (PPVman). The Capstesia application was loaded onto a Samsung Galaxy S4 phone. A physiologic simulator including PPV was used to display arterial waveforms on a computer screen. Data were obtained with different sweep speeds (6 and 12 mm/s) and randomly generated PPV values (from 2% to 24%), pulse pressure (30, 45, and 60 mm Hg), heart rates (60-80 bpm), and respiratory rates (10-15 breaths/min) on the simulator. Each metric was recorded 5 times at an arterial height scale X1 (PPV5appX1) and 5 times at an arterial height scale X3 (PPV5appX3). Reproducibility of PPVapp and PPVman was determined from the 5 pictures of the same hemodynamic profile. The effect of sweep speed, arterial waveform scale (X1 or X3), and number of images captured was assessed by a Bland-Altman analysis. The measurement error (ME) was calculated for each pair of data. A receiver operating characteristic curve analysis determined the ability of PPVapp to discriminate a PPVman > 13%. Four hundred eight pairs of PPVapp and PPVman were analyzed. The reproducibility of PPVapp and PPVman was 10% (interquartile range, 7%-14%) and 6% (interquartile range, 3%-10%), respectively, allowing a threshold ME of 12%. The overall mean bias for PPVappX1 was 1.1% within limits of -1.4% (95% confidence interval [CI], -1.7 to -1.1) to +3.5% (95% CI, +3.2 to +3.8). Averaging 5 values of PPVappX1 with a sweep speed of 12 mm/s resulted in the smallest bias (+0.6%) and the best limits of agreement (±1.3%). ME of PPVapp was <12% whenever 3, 4, or 5 pictures were taken to average PPVapp. The best predictive value for PPVapp to detect a PPVman > 13% was obtained for PPVappX1 by averaging 5 pictures showing a PPVapp threshold of 13.5% (95% CI, 12.9-15.2) and a receiver operating characteristic curve area of 0.989 (95% CI, 0.963-0.998) with a sensitivity of 97% and a specificity of 94%. Our findings show that the Capstesia PPV calculation is a dependable substitute for standard manual PPV determination in a highly controlled environment (simulator study). Further studies are warranted to validate this mobile feature extraction technology to predict fluid responsiveness in real conditions.

Acquiring Research-grade ALSM Data in the Commercial Marketplace

NASA Astrophysics Data System (ADS)

Haugerud, R. A.; Harding, D. J.; Latypov, D.; Martinez, D.; Routh, S.; Ziegler, J.

2003-12-01

The Puget Sound Lidar Consortium, working with TerraPoint, LLC, has procured a large volume of ALSM (topographic lidar) data for scientific research. Research-grade ALSM data can be characterized by their completeness, density, and accuracy. Complete data include-at a minimum-X, Y, Z, time, and classification (ground, vegetation, structure, blunder) for each laser reflection. Off-nadir angle and return number for multiple returns are also useful. We began with a pulse density of 1/sq m, and after limited experiments still find this density satisfactory in the dense second-growth forests of western Washington. Lower pulse densities would have produced unacceptably limited sampling in forested areas and aliased some topographic features. Higher pulse densities do not produce markedly better topographic models, in part because of limitations of reproducibility between the overlapping survey swaths used to achieve higher density. Our experience in a variety of forest types demonstrates that the fraction of pulses that produce ground returns varies with vegetation cover, laser beam divergence, laser power, and detector sensitivity, but have not quantified this relationship. The most significant operational limits on vertical accuracy of ALSM appear to be instrument calibration and the accuracy with which returns are classified as ground or vegetation. TerraPoint has recently implemented in-situ calibration using overlapping swaths (Latypov and Zosse, 2002, see http://www.terrapoint.com/News_damirACSM_ASPRS2002.html). On the consumer side, we routinely perform a similar overlap analysis to produce maps of relative Z error between swaths; we find that in bare, low-slope regions the in-situ calibration has reduced this internal Z error to 6-10 cm RMSE. Comparison with independent ground control points commonly illuminates inconsistencies in how GPS heights have been reduced to orthometric heights. Once these inconsistencies are resolved, it appears that the internal errors are the bulk of the error of the survey. The error maps suggest that with in-situ calibration, minor time-varying errors with a period of circa 1 sec are the largest remaining source of survey error. For forested terrain, limited ground penetration and errors in return classification can severely limit the accuracy of resulting topographic models. Initial work by Haugerud and Harding demonstrated the feasibility of fully-automatic return classification; however, TerraPoint has found that better results can be obtained more effectively with 3rd-party classification software that allows a mix of automated routines and human intervention. Our relationship has been evolving since early 2000. Important aspects of this relationship include close communication between data producer and consumer, a willingness to learn from each other, significant technical expertise and resources on the consumer side, and continued refinement of achievable, quantitative performance and accuracy specifications. Most recently we have instituted a slope-dependent Z accuracy specification that TerraPoint first developed as a heuristic for surveying mountainous terrain in Switzerland. We are now working on quantifying the internal consistency of topographic models in forested areas, using a variant of overlap analysis, and standards for the spatial distribution of internal errors.

Pulse analysis of acoustic emission signals. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Houghton, J. R.

1976-01-01

A method for the signature analysis of pulses in the frequency domain and the time domain is presented. Fourier spectrum, Fourier transfer function, shock spectrum and shock spectrum ratio are examined in the frequency domain analysis, and pulse shape deconvolution is developed for use in the time domain analysis. To demonstrate the relative sensitivity of each of the methods to small changes in the pulse shape, signatures of computer modeled systems with analytical pulses are presented. Optimization techniques are developed and used to indicate the best design parameters values for deconvolution of the pulse shape. Several experiments are presented that test the pulse signature analysis methods on different acoustic emission sources. These include acoustic emissions associated with: (1) crack propagation, (2) ball dropping on a plate, (3) spark discharge and (4) defective and good ball bearings.

Contributions of aortic pulse wave velocity and backward wave pressure to variations in left ventricular mass are independent of each other.

PubMed

Bello, Hamza; Norton, Gavin R; Ballim, Imraan; Libhaber, Carlos D; Sareli, Pinhas; Woodiwiss, Angela J

2017-05-01

Aortic pulse wave velocity (PWV) and backward waves, as determined from wave separation analysis, predict cardiovascular events beyond brachial blood pressure. However, the extent to which these aortic hemodynamic variables contribute independent of each other is uncertain. In 749 randomly selected participants of African ancestry, we therefore assessed the extent to which relationships between aortic PWV or backward wave pressures (Pb) (and hence central aortic pulse pressure [PPc]) and left ventricular mass index (LVMI) occur independent of each other. Aortic PWV, PPc, forward wave pressure (Pf), and Pb were determined using radial applanation tonometry and SphygmoCor software and LVMI using echocardiography; 44.5% of participants had an increased left ventricular mass indexed to height 1.7 . With adjustments for age, brachial systolic blood pressure or PP, and additional confounders, PPc and Pb, but not Pf, were independently related to LVMI and left ventricular hypertrophy (LVH) in both men and women. However, PWV was independently associated with LVMI in women (partial r = 0.16, P < .001), but not in men (partial r = 0.03), and PWV was independently associated with LVH in women (P < .05), but not in men (P = .07). With PWV and Pb included in the same multivariate regression models, PWV (partial r = 0.14, P < .005) and Pb (partial r = 0.10, P < .05) contributed to a similar extent to variations in LVMI in women. In addition, with PWV and Pb included in the same multivariate regression models, PWV (P < .05) and Pb (P < .02) contributed to LVH in women. In conclusion, aortic PWV and Pb (and hence pulse pressure) although both associated with LVMI and LVH produce effects which are independent of each other. Copyright © 2017 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.

Specification for a standard radar sea clutter model

NASA Astrophysics Data System (ADS)

Paulus, Richard A.

1990-09-01

A model for the average sea clutter radar cross section is proposed for the Oceanographic and Atmospheric Master Library. This model is a function of wind speed (or sea state), wind direction relative to the antenna, refractive conditions, radar antenna height, frequency, polarization, horizontal beamwidth, and compressed pulse length. The model is fully described, a FORTRAN 77 computer listing is provided, and test cases are given to demonstrate the proper operation of the program.

Numerical simulation of solitary waves on deep water with constant vorticity

NASA Astrophysics Data System (ADS)

Dosaev, A. S.; Shishina, M. I.; Troitskaya, Yu I.

2018-01-01

Characteristics of solitary deep water waves on a flow with constant vorticity are investigated by numerical simulation within the framework of fully nonlinear equations of motion (Euler equations) using the method of surface-tracking conformal coordinates. To ensure that solutions observed are stable, soliton formation as a result of disintegration of an initial pulse-like disturbance is modeled. Evidence is obtained that solitary waves with height above a certain threshold are unstable.

Interference Fringes Used to Determine Retinal Ganglion Cell Receptive Field Sizes.

DTIC Science & Technology

1982-07-01

National Technical Informtion -Tvc, b ~ ti I to the general public, including foreign n"atfonals.... This tecinical report has been reviewed and Is...adjusted to satisfy the follow- ing criteria: (a) tachycardia and transient hypertension in response to strong noxious stimuli, and ( b ) stage I or...tube voltage output for drifting interference fringes with a spatial frequency of 11.6 cycles/degree; B shows the histogram of the pulse-height

Dynamic Positron Emission Tomography [PET] in Man Using Small Bismuth Germanate Crystals

DOE R&D Accomplishments Database

Derenzo, S. E.; Budinger, T. F.; Huesman, R. H.; Cahoon, J. L.

1982-04-01

Primary considerations for the design of positron emission tomographs for medical studies in humans are the need for high imaging sensitivity, whole organ coverage, good spatial resolution, high maximum data rates, adequate spatial sampling with minimum mechanical motion, shielding against out of plane activity, pulse height discrimination against scattered photons, and timing discrimination against accidental coincidences. We discuss the choice of detectors, sampling motion, shielding, and electronics to meet these objectives.

Aircraft and satellite measurement of ocean wave directional spectra using scanning-beam microwave radars

NASA Technical Reports Server (NTRS)

Jackson, F. C.; Walton, W. T.; Baker, P. L.

1982-01-01

A microwave radar technique for remotely measuring the vector wave number spectrum of the ocean surface is described. The technique, which employs short-pulse, noncoherent radars in a conical scan mode near vertical incidence, is shown to be suitable for both aircraft and satellite application, the technique was validated at 10 km aircraft altitude, where we have found excellent agreement between buoy and radar-inferred absolute wave height spectra.

RSRE (Royal Signals and Radar Establishment) 1985 Research Review,

DTIC Science & Technology

1985-01-01

together with a 4-pulse canceller having signal processing allows adequate height time varied weighting . Temporal threshold accuracy and performance in...figure of 10 dB systems and is included within the Contraves achieved. Signal processing and target Seaguard defence system. It is a declaration are...6). This array is Taylor weighted by the t strip-line feed network to produce -29 dB Naval/Marine Radar first azimuthal sidelobe. The cosec2 low

Status of the Monte Carlo library least-squares (MCLLS) approach for non-linear radiation analyzer problems

NASA Astrophysics Data System (ADS)

Gardner, Robin P.; Xu, Libai

2009-10-01

The Center for Engineering Applications of Radioisotopes (CEAR) has been working for over a decade on the Monte Carlo library least-squares (MCLLS) approach for treating non-linear radiation analyzer problems including: (1) prompt gamma-ray neutron activation analysis (PGNAA) for bulk analysis, (2) energy-dispersive X-ray fluorescence (EDXRF) analyzers, and (3) carbon/oxygen tool analysis in oil well logging. This approach essentially consists of using Monte Carlo simulation to generate the libraries of all the elements to be analyzed plus any other required background libraries. These libraries are then used in the linear library least-squares (LLS) approach with unknown sample spectra to analyze for all elements in the sample. Iterations of this are used until the LLS values agree with the composition used to generate the libraries. The current status of the methods (and topics) necessary to implement the MCLLS approach is reported. This includes: (1) the Monte Carlo codes such as CEARXRF, CEARCPG, and CEARCO for forward generation of the necessary elemental library spectra for the LLS calculation for X-ray fluorescence, neutron capture prompt gamma-ray analyzers, and carbon/oxygen tools; (2) the correction of spectral pulse pile-up (PPU) distortion by Monte Carlo simulation with the code CEARIPPU; (3) generation of detector response functions (DRF) for detectors with linear and non-linear responses for Monte Carlo simulation of pulse-height spectra; and (4) the use of the differential operator (DO) technique to make the necessary iterations for non-linear responses practical. In addition to commonly analyzed single spectra, coincidence spectra or even two-dimensional (2-D) coincidence spectra can also be used in the MCLLS approach and may provide more accurate results.

Metal surface coloration by oxide periodic structures formed with nanosecond laser pulses

NASA Astrophysics Data System (ADS)

Veiko, Vadim; Karlagina, Yulia; Moskvin, Mikhail; Mikhailovskii, Vladimir; Odintsova, Galina; Olshin, Pavel; Pankin, Dmitry; Romanov, Valery; Yatsuk, Roman

2017-09-01

In this work, we studied a method of laser-induced coloration of metals, where small-scale spatially periodic structures play a key role in the process of color formation. The formation of such structures on a surface of AISI 304 stainless steel was demonstrated for the 1.06 μm fiber laser with nanosecond duration of pulses and random (elliptical) polarization. The color of the surface depends on the period, height and orientation of periodic surface structures. Adjustment of the polarization of the laser radiation or change of laser incidence angle can be used to control the orientation of the structures. The formation of markings that change their color under the different viewing angles becomes possible. The potential application of the method is metal product protection against falsification.

DESCANT--The DEuterated SCintillator Array for Neutron Tagging

NASA Astrophysics Data System (ADS)

Bildstein, Vinzenz; Garrett, P. E.; Bandyopadhay, D.; Bangay, J.; Bianco, L.; Demand, G.; Hadinia, B.; Leach, K. G.; Sumithrarachchi, C.; Wong, J.; Ashley, S. F.; Crider, B. P.; McEllistrem, M. T.; Peters, E. E.; Prados-Estévez, F. M.; Yates, S. W.; Vanhoy, J. R.; Ball, G. C.; Garnsworthy, A. B.; Hackman, G.; Pearson, C. J.; Sarazin, F.

2014-09-01

The DESCANT array at TRIUMF is designed to track neutrons from RIB experiments. DESCANT is composed of 70 close-packed deuterated organic liquid scintillators coupled to digital fast read-out ADC modules. This configuration will permit online pulse-shape discrimination between neutron and γ-ray events. The anisotropy of the n - d scattering will allow distinction of higher neutron multiplicities from scattering within the array and determination of the neutron energy spectrum directly from the pulse-height spectrum without using TOF. A prototype detector has been tested with monoenergetic neutrons at the accelerator laboratory of the University of Kentucky and a 24Mg(3He, n)26Si experiment has been performed with eight DESCANT detectors and two HPGe detectors. The results of the tests and the status of DESCANT will be presented.

Analysis of CRRES PHA Data for Low-Energy-Deposition Events

NASA Technical Reports Server (NTRS)

McNulty, P. J.; Hardage, Donna

2004-01-01

This effort analyzed the low-energy deposition Pulse Height Analyzer (PHA) data from the Combined Release and Radiation Effects Satellite (CRRES). The high-energy deposition data had been previously analyzed and shown to be in agreement with spallation reactions predicted by the Clemson University Proton Interactions in Devices (CUPID) simulation model and existing environmental and orbit positioning models (AP-8 with USAF B-L coordinates). The scope of this project was to develop and improve the CUPID model by increasing its range to lower incident particle energies, and to expand the modeling to include contributions from elastic interactions. Before making changes, it was necessary to identify experimental data suitable for benchmarking the codes; then, the models to the CRRES PHA data could be applied. It was also planned to test the model against available low-energy proton or neutron SEU data obtained with mono-energetic beams.

X-ray analysis of electron Bernstein wave heating in MST

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

Seltzman, A. H., E-mail: seltzman@wisc.edu; Anderson, J. K.; DuBois, A. M.

2016-11-15

A pulse height analyzing x-ray tomography system has been developed to detect x-rays from electron Bernstein wave heated electrons in the Madison symmetric torus reversed field pinch (RFP). Cadmium zinc telluride detectors are arranged in a parallel beam array with two orthogonal multi-chord detectors that may be used for tomography. In addition a repositionable 16 channel fan beam camera with a 55° field of view is used to augment data collected with the Hard X-ray array. The chord integrated signals identify target emission from RF heated electrons striking a limiter located 12° toroidally away from the RF injection port. Thismore » provides information on heated electron spectrum, transport, and diffusion. RF induced x-ray emission from absorption on harmonic electron cyclotron resonances in low current (<250 kA) RFP discharges has been observed.« less

Response function of single crystal synthetic diamond detectors to 1-4 MeV neutrons for spectroscopy of D plasmas

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

Rebai, M., E-mail: marica.rebai@mib.infn.it; Nocente, M.; Rigamonti, D.

2016-11-15

A Single-crystal Diamond (SD) detector prototype was installed at Joint European Torus (JET) in 2013 and the achieved results have shown its spectroscopic capability of measuring 2.5 MeV neutrons from deuterium plasmas. This paper presents measurements of the SD response function to monoenergetic neutrons, which is a key point for the development of a neutron spectrometer based on SDs and compares them with Monte Carlo simulations. The analysis procedure allows for a good reconstruction of the experimental results. The good pulse height energy resolution (equivalent FWHM of 80 keV at 2.5 MeV), gain stability, insensitivity to magnetic field, and compactmore » size make SDs attractive as compact neutron spectrometers of high flux deuterium plasmas, such as for instance those needed for the ITER neutron camera.« less

Error Analysis and Validation for Insar Height Measurement Induced by Slant Range

NASA Astrophysics Data System (ADS)

Zhang, X.; Li, T.; Fan, W.; Geng, X.

2018-04-01

InSAR technique is an important method for large area DEM extraction. Several factors have significant influence on the accuracy of height measurement. In this research, the effect of slant range measurement for InSAR height measurement was analysis and discussed. Based on the theory of InSAR height measurement, the error propagation model was derived assuming no coupling among different factors, which directly characterise the relationship between slant range error and height measurement error. Then the theoretical-based analysis in combination with TanDEM-X parameters was implemented to quantitatively evaluate the influence of slant range error to height measurement. In addition, the simulation validation of InSAR error model induced by slant range was performed on the basis of SRTM DEM and TanDEM-X parameters. The spatial distribution characteristics and error propagation rule of InSAR height measurement were further discussed and evaluated.

Observed Cloud Properties Above the Northern Indian Ocean During CARDEX 2012

NASA Astrophysics Data System (ADS)

Gao, L.; Wilcox, E. M.

2016-12-01

An analysis of cloud microphysical, macrophysical and radiative properties during the dry winter monsoon season above the northern Indian Ocean is presented. The Cloud Aerosol Radiative Forcing Experiment (CARDEX), conducted from 16 February to 30 March 2012 at the Maldives Climate Observatory on Hanimaadhoo (MCOH), used autonomous unmanned aerial vehicles (UAVs) to measure the aerosol profiles, water vapor flux and cloud properties concurrent with continuous ground measurements of surface aerosol and meteorological variables as well as the total-column precipitable water vapor (PWV) and the cloud liquid water path (LWP). Here we present the cloud properties only for the cases with lower atmospheric water vapor using the criterion that the PWV less than 40 kg/m2. This criterion acts to filter the data to control for the natural meteorological variability in the region according to previous studies. The high polluted case is found to correlate with warmer temperature, higher relative humidity in boundary layer and lower lifted condensation level (LCL). Micro Pulse Lidar (MPL) retrieved cloud base height coincides with calculated LCL height which is lower for high polluted case. Meanwhile satellite retrieved cloud top height didn't show obvious variation indicating cloud deepening which is consistent with the observed greater cloud LWP in high polluted case. Those high polluted clouds are associated with more cloud droplets and smaller effective radius and are generally becoming narrower due to the stronger cloud side evaporation-entrainment effect and becoming deeper due to more moist static energy. Clouds in high polluted condition become brighter with higher albedo which can cause a net shortwave forcing over -40 W/m2 in this region.

Estimating Forest Canopy Heights and Aboveground Biomass with Simulated ICESat-2 Data

NASA Astrophysics Data System (ADS)

Malambo, L.; Narine, L.; Popescu, S. C.; Neuenschwander, A. L.; Sheridan, R.

2016-12-01

The Ice, Cloud and Land Elevation Satellite (ICESat) 2 is scheduled for launch in 2017 and one of its overall science objectives will be to measure vegetation heights, which can be used to estimate and monitor aboveground biomass (AGB) over large spatial scales. This study serves to develop a methodology for utilizing vegetation data collected by ICESat-2 that will be on a five-year mission from 2017, for mapping forest canopy heights and estimating aboveground forest biomass (AGB). The specific objectives are to, (1) simulate ICESat-2 photon-counting lidar (PCL) data, (2) utilize simulated PCL data to estimate forest canopy heights and propose a methodology for upscaling PCL height measurements to obtain spatially contiguous coverage and, (3) estimate and map AGB using simulated PCL data. The laser pulse from ICESat-2 will be divided into three pairs of beams spaced approximately 3 km apart, with footprints measuring approximately 14 m in diameter and with 70 cm along-track intervals. Using existing airborne lidar data (ALS) for Sam Houston National Forest (SHNF) and known ICESat-2 beam locations, footprints are generated along beam locations and PCL data are then simulated from discrete return lidar points within each footprint. By applying data processing algorithms, photons are classified into top of canopy points and ground surface elevation points to yield tree canopy height values within each ICESat-2 footprint. AGB is then estimated using simple linear regression that utilizes AGB from a biomass map generated with ALS data for SHNF and simulated PCL height metrics for 100 m segments along ICESat-2 tracks. Two approaches also investigated for upscaling AGB estimates to provide wall-to-wall coverage of AGB are (1) co-kriging and (2) Random Forest. Height and AGB maps, which are the outcomes of this study, will demonstrate how data acquired by ICESat-2 can be used to measure forest parameters and in extension, estimate forest carbon for climate change initiatives.

Origin, Emission, and Propagation of P-H Pulses

NASA Astrophysics Data System (ADS)

Kikuchi, H.

2007-05-01

Origin, Emission, and Propagation of P-H Pulses H. Kikuchi Institute for Environmental Electromagnetics 3-8-18, Komagome, Toshima-ku, Tokyo 170, Japan e-mail: hkikuchi@mars.dti.ne.jp Abstract According to Pulinets, characters of P-H pulses is following. The registered emission has not continuous but pulsed character and has very wide frequency spectrum from kHz to more than hundred MHz. These two facts imply that should be the electric discharge-like emission similar to thunderstorm flashes emission. The emission is connected in some way with seismic activity and the emission intensity increases 12-24 hour before the seismic shock. Another intriguing factor is that emission is registered at large distances up to 500 km (some witness claim up to 1500 km). Taking into account that emission is registered at VHF band also, the source of emission cannot be situated on the ground. This paper puts forwards a model of P-H pulses generation based on "dust dynamics". Rotating ions ascending, for instance erupped metalic ions in the earth's crust into the atmosphere incorporating aerosols might be captured by diffuse dust layers which may exist below or beyond the electric mirror point produced by quadrupole-like thunder- cloud configurations or even form a portion of dust layers and could be a source-origin of P-H pulses that might be emitted by local electric discharges within diffuse dust layers somewhat similar to thundercloud discharges, though emission frequencies and characters are quite different, namely P-H pulses are over a wide range of frequencies, say from kHz to more than hundred MHz with pulsed character in contrast to lightning emission with more continuous character whose frequencies are 1 to 10 kHz. Such diffuse dust layers could be formed over a wide range of height in the troposphere, stratosphere, mesosphere and the thermosphere. Propagation distance of P-H pulses are very large up to 500-1500 km.

A Quantitative Analysis of Pulsed Signals Emitted by Wild Bottlenose Dolphins.

PubMed

Luís, Ana Rita; Couchinho, Miguel N; Dos Santos, Manuel E

2016-01-01

Common bottlenose dolphins (Tursiops truncatus), produce a wide variety of vocal emissions for communication and echolocation, of which the pulsed repertoire has been the most difficult to categorize. Packets of high repetition, broadband pulses are still largely reported under a general designation of burst-pulses, and traditional attempts to classify these emissions rely mainly in their aural characteristics and in graphical aspects of spectrograms. Here, we present a quantitative analysis of pulsed signals emitted by wild bottlenose dolphins, in the Sado estuary, Portugal (2011-2014), and test the reliability of a traditional classification approach. Acoustic parameters (minimum frequency, maximum frequency, peak frequency, duration, repetition rate and inter-click-interval) were extracted from 930 pulsed signals, previously categorized using a traditional approach. Discriminant function analysis revealed a high reliability of the traditional classification approach (93.5% of pulsed signals were consistently assigned to their aurally based categories). According to the discriminant function analysis (Wilk's Λ = 0.11, F3, 2.41 = 282.75, P < 0.001), repetition rate is the feature that best enables the discrimination of different pulsed signals (structure coefficient = 0.98). Classification using hierarchical cluster analysis led to a similar categorization pattern: two main signal types with distinct magnitudes of repetition rate were clustered into five groups. The pulsed signals, here described, present significant differences in their time-frequency features, especially repetition rate (P < 0.001), inter-click-interval (P < 0.001) and duration (P < 0.001). We document the occurrence of a distinct signal type-short burst-pulses, and highlight the existence of a diverse repertoire of pulsed vocalizations emitted in graded sequences. The use of quantitative analysis of pulsed signals is essential to improve classifications and to better assess the contexts of emission, geographic variation and the functional significance of pulsed signals.

Analysis of folded pulse forming line operation.

PubMed

Domonkos, M T; Watrous, J; Parker, J V; Cavazos, T; Slenes, K; Heidger, S; Brown, D; Wilson, D

2014-09-01

A compact pulse forming line (CPFL) concept based on a folded transmission line and high-breakdown strength dielectric was explored through an effort combining proof-of-principle experiments with electromagnetic modeling. A small-scale folded CPFL was fabricated using surface-mount ceramic multilayer capacitors. The line consisted of 150 capacitors close-packed in parallel and delivered a 300 ns flat-top pulse. The concept was carried to a 10 kV class device using a polymer-ceramic nanocomposite dielectric with a permittivity of 37.6. The line was designed for a 161 ns FWHM length pulse into a matched load. The line delivered a 110 ns FWHM pulse, and the pulse peak amplitude exceeded the matched load ideal. Transient electromagnetic analysis using the particle-in-cell code ICEPIC was conducted to examine the nature of the unexpected pulse shortening and distortion. Two-dimensional analysis failed to capture the anomalous behavior. Three-dimensional analysis replicated the pulse shape and revealed that the bends were largely responsible for the pulse shortening. The bends not only create the expected reflection of the incident TEM wave but also produce a non-zero component of the Poynting vector perpendicular to the propagation direction of the dominant electromagnetic wave, resulting in power flow largely external to the PFL. This analysis explains both the pulse shortening and the amplitude of the pulse.

Analysis of folded pulse forming line operation

NASA Astrophysics Data System (ADS)

Domonkos, M. T.; Watrous, J.; Parker, J. V.; Cavazos, T.; Slenes, K.; Heidger, S.; Brown, D.; Wilson, D.

2014-09-01

A compact pulse forming line (CPFL) concept based on a folded transmission line and high-breakdown strength dielectric was explored through an effort combining proof-of-principle experiments with electromagnetic modeling. A small-scale folded CPFL was fabricated using surface-mount ceramic multilayer capacitors. The line consisted of 150 capacitors close-packed in parallel and delivered a 300 ns flat-top pulse. The concept was carried to a 10 kV class device using a polymer-ceramic nanocomposite dielectric with a permittivity of 37.6. The line was designed for a 161 ns FWHM length pulse into a matched load. The line delivered a 110 ns FWHM pulse, and the pulse peak amplitude exceeded the matched load ideal. Transient electromagnetic analysis using the particle-in-cell code ICEPIC was conducted to examine the nature of the unexpected pulse shortening and distortion. Two-dimensional analysis failed to capture the anomalous behavior. Three-dimensional analysis replicated the pulse shape and revealed that the bends were largely responsible for the pulse shortening. The bends not only create the expected reflection of the incident TEM wave but also produce a non-zero component of the Poynting vector perpendicular to the propagation direction of the dominant electromagnetic wave, resulting in power flow largely external to the PFL. This analysis explains both the pulse shortening and the amplitude of the pulse.

Baseline Error Analysis and Experimental Validation for Height Measurement of Formation Insar Satellite

NASA Astrophysics Data System (ADS)

Gao, X.; Li, T.; Zhang, X.; Geng, X.

2018-04-01

In this paper, we proposed the stochastic model of InSAR height measurement by considering the interferometric geometry of InSAR height measurement. The model directly described the relationship between baseline error and height measurement error. Then the simulation analysis in combination with TanDEM-X parameters was implemented to quantitatively evaluate the influence of baseline error to height measurement. Furthermore, the whole emulation validation of InSAR stochastic model was performed on the basis of SRTM DEM and TanDEM-X parameters. The spatial distribution characteristics and error propagation rule of InSAR height measurement were fully evaluated.

[Research on a non-invasive pulse wave detection and analysis system].

PubMed

Li, Ting; Yu, Gang

2008-10-01

A novel non-invasive pulse wave detection and analysis system has been developed, including the software and the hardware. Bi-channel signals can be acquired, stored and shown on the screen dynamically at the same time. Pulse wave can be reshown and printed after pulse wave analysis and pulse wave velocity analysis. This system embraces a computer which is designed for fast data saving, analyzing and processing, and a portable data sampling machine which is based on a singlechip. Experimental results have shown that the system is stable and easy to use, and the parameters are calculated accurately.

Relationship Between Aerosol Optical Depth and Particulate Matter Over Singapore: Effects of Aerosol Vertical Distributions

NASA Technical Reports Server (NTRS)

Chew, Boo Ning; Campbell, James; Hyer, Edward J.; Salinas, Santo V.; Reid, Jeffrey S.; Welton, Ellsworth J.; Holben, Brent N.; Liew, Soo Chin

2016-01-01

As part of the Seven Southeast Asian Studies (7SEAS) program, an Aerosol Robotic Network (AERONET) sun photometer and a Micro-Pulse Lidar Network (MPLNET) instrument have been deployed at Singapore to study the regional aerosol environment of the Maritime Continent (MC). In addition, the Navy Aerosol Analysis and Prediction System (NAAPS) is used to model aerosol transport over the region. From 24 September 2009 to 31 March 2011, the relationships between ground-, satellite- and model-based aerosol optical depth (AOD) and particulate matter with aerodynamic equivalent diameters less than 2.5 microns (PM2.5) for air quality applications are investigated. When MPLNET-derived aerosol scale heights are applied to normalize AOD for comparison with surface PM2.5 data, the empirical relationships are shown to improve with an increased 11%, 10% and 5% in explained variances, for AERONET, MODIS and NAAPS respectively. The ratios of root mean square errors to standard deviations for the relationships also show corresponding improvements of 8%, 6% and 2%. Aerosol scale heights are observed to be bimodal with a mode below and another above the strongly-capped/deep near-surface layer (SCD; 0-1.35 km). Aerosol extinctions within the SCD layer are well-correlated with surface PM2.5 concentrations, possibly due to strong vertical mixing in the region.

Hemodynamic Correlates of Abnormal Aortic Root Dimension in an Adult Population: The Strong Heart Study.

PubMed

de Simone, Giovanni; Roman, Mary J; De Marco, Marina; Bella, Jonathan N; Izzo, Raffaele; Lee, Elisa T; Devereux, Richard B

2015-09-28

We evaluated the relationship of aortic root dimension (ARD) with flow output and both peripheral and central blood pressure, using multivariable equations predicting ideal sex-specific ARD at a given age and body height. We measured echocardiographic diastolic ARD at the sinuses of Valsalva in 3160 adults (aged 42±16 years, 61% women) from the fourth examination of the Strong Heart Study who were free of prevalent coronary heart disease, and we compared measured data with the theoretical predicted value to calculate a z score. Central blood pressure was estimated by applanation tonometry of the radial artery in 2319 participants. ARD z scores were divided into tertiles representing small, normal, and large ARD. Participants with large ARD exhibited greater prevalence of central obesity and higher levels of inflammatory markers and lipids (0.05

High-rate x-ray spectroscopy in mammography with a CdTe detector: a digital pulse processing approach.

PubMed

Abbene, L; Gerardi, G; Principato, F; Del Sordo, S; Ienzi, R; Raso, G

2010-12-01

Direct measurement of mammographic x-ray spectra under clinical conditions is a difficult task due to the high fluence rate of the x-ray beams as well as the limits in the development of high resolution detection systems in a high counting rate environment. In this work we present a detection system, based on a CdTe detector and an innovative digital pulse processing (DPP) system, for high-rate x-ray spectroscopy in mammography. The DPP system performs a digital pile-up inspection and a digital pulse height analysis of the detector signals, digitized through a 14-bit, 100 MHz digitizer, for x-ray spectroscopy even at high photon counting rates. We investigated on the response of the digital detection system both at low (150 cps) and at high photon counting rates (up to 500 kcps) by using monoenergetic x-ray sources and a nonclinical molybdenum anode x-ray tube. Clinical molybdenum x-ray spectrum measurements were also performed by using a pinhole collimator and a custom alignment device. The detection system shows excellent performance up to 512 kcps with an energy resolution of 4.08% FWHM at 22.1 keV. Despite the high photon counting rate (up to 453 kcps), the molybdenum x-ray spectra, measured under clinical conditions, are characterized by a low number of pile-up events. The agreement between the attenuation curves and the half value layer values, obtained from the measured spectra, simulated spectra, and from the exposure values directly measured with an ionization chamber, also shows the accuracy of the measurements. These results make the proposed detection system a very attractive tool for both laboratory research and advanced quality controls in mammography.

Initiation Phenomena in Pulsed Chemical Lasers

DTIC Science & Technology

1978-10-01

2-3 4 Normalized Cavity llumination Contours.............. 2-5 5 Case B ....... * . . .. ... . ...... . . . .. .. . ... . 2-6 6 Nonuniformity in...improvement in illumination uniformity were obtained. Figure 6 shows the decrease in initiation nonuniformity with increasing numbers of lamps in the...Flow10 Entry and Exit < 6 4 2 10 14 18 22 26 30 34 Number of Lamps 1.0 1.4 1.8 2.2 2.6 3.0 3.4 Cavity Width/Cavity Height Figure 6. Nonuniformity in

A High Resolution Clinical PET with Breast and Whole Body Transfigurations

DTIC Science & Technology

2006-08-01

1999. [6] Inst. Inorganic Chemistry, Siberian Branch, Russian Acad. Sci. 3, Acad. Lavrentyev Prospect, Novosibirsk, Russia. [7] White Reflecting Paint...46, no.6, pp. 491-497, 1999. [6] Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Science 3, Acad.Lavrentyev Prospect, 630090...demanding, higher spatial resolution 8 x 8 array (2.3 x 2.3 x 10 mm BGO) for mouse PET with shallower crystals, the pulse-height ratio was 0.73 with an

The POPOP4 library and codes for preparing secondary gamma-ray production cross sections

NASA Technical Reports Server (NTRS)

Ford, W. E., III

1972-01-01

The POPOP4 code for converting secondary gamma ray yield data to multigroup secondary gamma ray production cross sections and the POPOP4 library of secondary gamma ray yield data are described. Recent results of the testing of uranium and iron data sets from the POPOP4 library are given. The data sets were tested by comparing calculated secondary gamma ray pulse height spectra measured at the ORNL TSR-II reactor.

Avalanche photodiode for measurement of low-energy electrons

NASA Astrophysics Data System (ADS)

Ogasawara, K.; Asamura, K.; Mukai, T.; Saito, Y.

2005-06-01

We report on the performance of an Avalanche Photodiode (APD) produced by Hamamatsu Photonics Co. Ltd. (Type Z7966-20) for measurements of low energy electrons. We have set up an electron gun, which can generate a 1-20 keV electron beam impinging onto the APD in a vacuum chamber. The result shows that the pulse height distribution (PHD) of the APD signal exhibits a significant peak for electrons with energies above 8 keV, and the variation of the PHD peak shows a good linearity with the energy of incident electrons. The energy resolution is quite good, though it slightly depends on the electron energy. In the case of low-energies (lower than 10 keV), the pulse height distribution has a characteristic tail on the low energy side, and the energy resolution becomes a little worse. The position of the peak appears on a slightly lower channel than is expected from data at higher energies (near 20 keV). Qualitatively, the low-energy tail is caused by the dead-layer on the surface of the device. The nonlinearity and the worse resolution of the peaks for higher energy electrons may have resulted from a space-charge effect due to created e-h pairs. For a quantitative understanding, we have made a Monte Carlo particle simulation of charge transport and collection inside the APD.

Characterization of Fissile Assemblies Using Low-Efficiency Detection Systems

DOE PAGES

Chapline, George F.; Verbeke, Jerome M.

2017-02-02

Here, we have investigated the possibility that the amount, chemical form, multiplication, and shape of the fissile material in an assembly can be passively assayed using scintillator detection systems by only measuring the fast neutron pulse height distribution and distribution of time intervals Δt between fast neutrons. We have previously demonstrated that the alpha-ratio can be obtained from the observed pulse height distribution for fast neutrons. In this paper we report that we report that when the distribution of time intervals is plotted as a function of logΔt, the position of the correlated neutron peak is nearly independent of detectormore » efficiency and determines the internal relaxation rate for fast neutrons. If this information is combined with knowledge of the alpha-ratio, then the position of the minimum between the correlated and uncorrelated peaks can be used to rapidly estimate the mass, multiplication, and shape of fissile material. This method does not require a priori knowledge of either the efficiency for neutron detection or the alpha-ratio. Although our method neglects 3-neutron correlations, we have used previously obtained experimental data for metallic and oxide forms of Pu to demonstrate that our method yields good estimates for multiplications as large as 2, and that the only constraint on detector efficiency/observation time is that a peak in the interval time distribution due to correlated neutrons is visible.« less

[Gas chromatography with a Pulsed discharge helium ionization detector for measurement of molecular hydrogen(H2) in the atmosphere].

PubMed

Luan, Tian; Fang, Shuang-xi; Zhou, Ling-xi; Wang, Hong-yang; Zhang, Gen

2015-01-01

A high precision GC system with a pulsed discharge helium ionization detector was set up based on the commercial Agilent 7890A gas chromatography. The gas is identified by retention time and the concentration is calculated through the peak height. Detection limit of the system is about 1 x 10(-9) (mole fraction, the same as below). The standard deviation of 140 continuous injections with a standard cylinder( concentration is roughly 600 x 10(-9)) is better than 0.3 x 10(-9). Between 409.30 x 10(-9) and 867.74 x 10(-9) molecular hydrogen mole fractions and peak height have good linear response. By using two standards to quantify the air sample, the precision meets the background molecular hydrogen compatibility goal within the World Meteorological Organization/Global Atmosphere Watch (WMO/GAW) program. Atmospheric molecular hydrogen concentration at Guangzhou urban area was preliminarily measured by this method from January to November 2013. The results show that the atmospheric molecular hydrogen mole fraction varies from 450 x 10(-9) to 700 x 10(-9) during the observation period, with the lowest value at 14:00 (Beijing time, the same as below) and the peak value at 20:00. The seasonal variation of atmospheric hydrogen at Guangzhou area was similar with that of the same latitude stations in northern hemisphere.

Temperature dependent electrical properties of pulse laser deposited Au/Ni/β-(AlGa)2O3 Schottky diode

NASA Astrophysics Data System (ADS)

Feng, Qian; Feng, Zhaoqing; Hu, Zhuangzhuang; Xing, Xiangyu; Yan, Guangshuo; Zhang, Jincheng; Xu, Yongkuan; Lian, Xiaozheng; Hao, Yue

2018-02-01

We have demonstrated the epitaxial growth of a β-(Al0.08Ga0.92)2O3 film on a β-Ga2O3 (010) substrate through pulsed laser deposition. The temperature-dependent electrical characteristics of Au/Ni/β-(Al0.08Ga0.92)2O3 Schottky diodes were investigated in the temperature range of 300-573 K, using thermionic emission theory to calculate the Schottky diode parameters. The barrier height ϕb was found to increase, while the ideality factor n and the series resistance Rs were found to decrease with increasing temperatures. The calculated values of ϕb and n varied from 0.81 eV and 2.29 at 300 K to 1.02 eV and 1.65 at 573 K. The temperature-dependent I-V characteristics of the Schottky diode have shown the Gaussian distribution, yielding a mean barrier height of 1.23 eV and a standard deviation of 0.147 V, respectively. A modified Richardson plot of ln (Is /T2 )-(q2σs2 /2 k2T2 ) versus q/2kT gives ϕb 0 ¯ and A* as 1.24 eV and 44.3 A cm-2 K-2, showing the promise of Ni/β-(AlGa)2O3 as a Schottky diode rectifier.

Comparisons of modeled height predictions to ocular height estimates

Treesearch

W.A. Bechtold; S.J. Zarnoch; W.G. Burkman

1998-01-01

Equations used by USDA Forest Service Forest Inventory and Analysis projects to predict individual tree heights on the basis of species and d.b.h. were improved by the addition of mean overstory height. However, ocular estimates of total height by field crews were more accurate than the statistically improved models, especially for hardwood species. Height predictions...

Nanomedicine photoluminescence crystal-inspired brain sensing approach

NASA Astrophysics Data System (ADS)

Fang, Yan; Wang, Fangzhen; Wu, Rong

2018-02-01

Precision sensing needs to overcome a gap of a single atomic step height standard. In response to the cutting-edge challenge, a heterosingle molecular nanomedicine crystal was developed wherein a nanomedicine crystal height less than 1 nm was designed and selfassembled on a substrate of either a highly ordered and freshly separated graphite or a N-doped silicon with hydrogen bonding by a home-made hybrid system of interacting single bioelectron donor-acceptor and a single biophoton donor-acceptor according to orthogonal mathematical optimization scheme, and an atomic spatial resolution conducting atomic force microscopy (C-AFM) with MHz signal processing by a special transformation of an atomic force microscopy (AFM) and a scanning tunneling microscopy (STM) were employed, wherein a z axis direction UV-VIS laser interferometer and a feedback circuit were used to achieve the minimized uncertainty of a micro-regional structure height and its corresponding local differential conductance quantization (spin state) process was repeatedly measured with a highly time resolution, as well as a pulsed UV-VIS laser micro-photoluminescence (PL) spectrum with a single photon resolution was set up by traceable quantum sensing and metrology relied up a quantum electrical triangle principle. The coupling of a single bioelectron conducting, a single biophoton photoluminescence, a frequency domain temporal spin phase in nanomedicine crystal-inspired sensing methods and sensor technologies were revealed by a combination of C-AFM and PL measurement data-based mathematic analyses1-3, as depicted in Figure 1 and repeated in nanomedicine crystals with a single atomic height. It is concluded that height-current-phase uncertainty correlation pave a way to develop a brain imaging and a single atomic height standard, quantum sensing, national security, worldwide impact1-3 technology and beyond.

Associations between height and blood pressure in the United States population.

PubMed

Bourgeois, Brianna; Watts, Krista; Thomas, Diana M; Carmichael, Owen; Hu, Frank B; Heo, Moonseong; Hall, John E; Heymsfield, Steven B

2017-12-01

The mechanisms linking short stature with an increase in cardiovascular and cerebrovascular disease risk remain elusive. This study tested the hypothesis that significant associations are present between height and blood pressure in a representative sample of the US adult population.Participants were 12,988 men and women from a multiethnic sample (age ≥ 18 years) evaluated in the 1999 to 2006 National Health and Nutrition Examination Survey who were not taking antihypertensive medications and who had complete height, weight, % body fat, and systolic and diastolic arterial blood pressure (SBP and DBP) measurements; mean arterial blood pressure and pulse pressure (MBP and PP) were calculated. Multiple regression models for men and women were developed with each blood pressure as dependent variable and height, age, race/ethnicity, body mass index, % body fat, socioeconomic status, activity level, and smoking history as potential independent variables.Greater height was associated with significantly lower SBP and PP, and higher DBP (all P < .001) in combined race/ethnic-sex group models beginning in the 4th decade. Predicted blood pressure differences between people who are short and tall increased thereafter with greater age except for MBP. Socioeconomic status, activity level, and smoking history did not consistently contribute to blood pressure prediction models.Height-associated blood pressure effects were present in US adults who appeared in the 4th decade and increased in magnitude with greater age thereafter. These observations, in the largest and most diverse population sample evaluated to date, provide support for postulated mechanisms linking adult stature with cardiovascular and cerebrovascular disease risk. Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.

NASA's Space Lidar Measurements of Earth and Planetary Surfaces

NASA Technical Reports Server (NTRS)

Abshire, James B.

2010-01-01

A lidar instrument on a spacecraft was first used to measure planetary surface height and topography on the Apollo 15 mission to the Moon in 1971, The lidar was based around a flashlamp-pumped ruby laser, and the Apollo 15-17 missions used them to make a few thousand measurements of lunar surface height from orbit. With the advent of diode pumped lasers in the late 1980s, the lifetime, efficiency, resolution and mass of lasers and space lidar all improved dramatically. These advances were utilized in NASA space missions to map the shape and surface topography of Mars with > 600 million measurements, demonstrate initial space measurements of the Earth's topography, and measured the detailed shape of asteroid. NASA's ICESat mission in Earth orbit just completed its polar ice measurement mission with almost 2 billion measurements of the Earth's surface and atmosphere, and demonstrated measurements to Antarctica and Greenland with a height resolution of a few em. Space missions presently in cruise phase and in operation include those to Mercury and a topographic mapping mission of the Moon. Orbital lidar also have been used in experiments to demonstrate laser ranging over planetary distances, including laser pulse transmission from Earth to Mars orbit. Based on the demonstrated value of the measurements, lidar is now the preferred measurement approach for many new scientific space missions. Some missions planned by NASA include a planetary mission to measure the shape and dynamics of Europa, and several Earth orbiting missions to continue monitoring ice sheet heights, measure vegetation heights, assess atmospheric CO2 concentrations, and to map the Earth surface topographic heights with 5 m spatial resolution. This presentation will give an overview of history, ongoing work, and plans for using space lidar for measurements of the surfaces of the Earth and planets.

Non-Geiger-Mode Single-Photon Avalanche Detector with Low Excess Noise

NASA Technical Reports Server (NTRS)

Zhao, Kai; Lo, YuHwa; Farr, William

2010-01-01

This design constitutes a self-resetting (gain quenching), room-temperature operational semiconductor single-photon-sensitive detector that is sensitive to telecommunications optical wavelengths and is scalable to large areas (millimeter diameter) with high bandwidth and efficiencies. The device can detect single photons at a 1,550-nm wavelength at a gain of 1 x 10(exp 6). Unlike conventional single photon avalanche detectors (SPADs), where gain is an extremely sensitive function to the bias voltage, the multiplication gain of this device is stable at 1 x 10(exp 6) over a wide range of bias from 30.2 to 30.9 V. Here, the multiplication gain is defined as the total number of charge carriers contained in one output pulse that is triggered by the absorption of a single photon. The statistics of magnitude of output signals also shows that the device has a very narrow pulse height distribution, which demonstrates a greatly suppressed gain fluctuation. From the histograms of both pulse height and pulse charge, the equivalent gain variance (excess noise) is between 1.001 and 1.007 at a gain of 1 x 10(exp 6). With these advantages, the device holds promise to function as a PMT-like photon counter at a 1,550- nm wavelength. The epitaxial layer structure of the device allows photons to be absorbed in the InGaAs layer, generating electron/hole (e-h) pairs. Driven by an electrical field in InGaAs, electrons are collected at the anode while holes reach the multiplication region (InAlAs p-i-n structure) and trigger the avalanche process. As a result, a large number of e-h pairs are created, and the holes move toward the cathode. Holes created by the avalanche process gain large kinetic energy through the electric field, and are considered hot. These hot holes are cooled as they travel across a p -InAlAs low field region, and are eventually blocked by energy barriers formed by the InGaAsP/ InAlAs heterojunctions. The composition of the InGaAsP alloy was chosen to have an 80 meV valance band offset with InAlAs, which is high enough to hinder the transport of the already cooled holes. Being stopped by the energy barrier, holes are accumulated at the junctions to shield the electric field, resulting in a decrease of the electric field in the multiplication region. Because the impact ionization rate is extremely sensitive to the magnitude of the electric field, the field-screening effect drastically reduces the impact ionization rate and quenches the output signals. After the avalanche pulse signal is self-quenched, the accumulated holes at the InGaAsP/ InAlAs interface escape the energy barrier through thermal excitation and tunneling and finally leave the device. The device is thus reset and ready for subsequent photon detection. This recovery time is controlled by the height of the energy barrier and the hole-cooling rate.

Design and application of pulse information acquisition and analysis system with dynamic recognition in traditional Chinese medicine.

PubMed

Zhang, Jian; Niu, Xin; Yang, Xue-zhi; Zhu, Qing-wen; Li, Hai-yan; Wang, Xuan; Zhang, Zhi-guo; Sha, Hong

2014-09-01

To design the pulse information which includes the parameter of pulse-position, pulse-number, pulse-shape and pulse-force acquisition and analysis system with function of dynamic recognition, and research the digitalization and visualization of some common cardiovascular mechanism of single pulse. To use some flexible sensors to catch the radial artery pressure pulse wave and utilize the high frequency B mode ultrasound scanning technology to synchronously obtain the information of radial extension and axial movement, by the way of dynamic images, then the gathered information was analyzed and processed together with ECG. Finally, the pulse information acquisition and analysis system was established which has the features of visualization and dynamic recognition, and it was applied to serve for ten healthy adults. The new system overcome the disadvantage of one-dimensional pulse information acquisition and process method which was common used in current research area of pulse diagnosis in traditional Chinese Medicine, initiated a new way of pulse diagnosis which has the new features of dynamic recognition, two-dimensional information acquisition, multiplex signals combination and deep data mining. The newly developed system could translate the pulse signals into digital, visual and measurable motion information of vessel.

The effects of cadmium pulse dosing on physiological traits and growth of the submerged macrophyte Vallisneria spinulosa and phytoplankton biomass: a mesocosm study.

PubMed

Liu, Hui; Cao, Yu; Li, Wei; Zhang, Zhao; Jeppesen, Erik; Wang, Wei

2017-06-01

Pulse inputs of heavy metals are expected to increase with a higher frequency of extreme climate events (heavy rain), leading to stronger erosion of contaminated and fertilized farmland soils to freshwaters, with potentially adverse effects on lake ecosystems. We conducted a 5-month mesocosm study to elucidate the responses of the submerged macrophyte Vallisneria spinulosa and phytoplankton to four different doses of cadmium (Cd): 0 (control), 0.05, 0.5, and 5 g m -2 (CK, I, II, and III, respectively) under mesotrophic conditions. We found that total phosphorus concentrations were larger in the three Cd pulse treatments, whereas total nitrogen concentrations did not differ among the four treatments. The contents of chlorophyll a and soluble sugar in macrophyte leaves decreased in III, and total biomass, ramet number, plant height, and total stolon length of macrophytes were lower in both II and III. In contrast, abundances of the three main phytoplankton taxa-Cyanophyta, Chlorophyta, and Bacillariophyta-did not differ among treatments. Total phytoplankton biomass was, however, marginally lower in CK than in the Cd treatments. We conclude that exposure to strong Cd pulses led to significantly reduced growth of macrophytes, while no obvious effect appeared for phytoplankton.

Atmospheric Multiple Scattering Effects on GLAS Altimetry. Part 2; Analysis of Expected Errors in Antarctic Altitude Measurements

NASA Technical Reports Server (NTRS)

Mahesh, Ashwin; Spinhirne, James D.; Duda, David P.; Eloranta, Edwin W.; Starr, David O'C (Technical Monitor)

2001-01-01

The altimetry bias in GLAS (Geoscience Laser Altimeter System) or other laser altimeters resulting from atmospheric multiple scattering is studied in relationship to current knowledge of cloud properties over the Antarctic Plateau. Estimates of seasonal and interannual changes in the bias are presented. Results show the bias in altitude from multiple scattering in clouds would be a significant error source without correction. The selective use of low optical depth clouds or cloudfree observations, as well as improved analysis of the return pulse such as by the Gaussian method used here, are necessary to minimize the surface altitude errors. The magnitude of the bias is affected by variations in cloud height, cloud effective particle size and optical depth. Interannual variations in these properties as well as in cloud cover fraction could lead to significant year-to-year variations in the altitude bias. Although cloud-free observations reduce biases in surface elevation measurements from space, over Antarctica these may often include near-surface blowing snow, also a source of scattering-induced delay. With careful selection and analysis of data, laser altimetry specifications can be met.

Sensing mode atomic force microscope

DOEpatents

Hough, Paul V. C.; Wang, Chengpu

2003-01-01

An atomic force microscope utilizes a pulse release system and improved method of operation to minimize contact forces between a probe tip affixed to a flexible cantilever and a specimen being measured. The pulse release system includes a magnetic particle affixed proximate the probe tip and an electromagnetic coil. When energized, the electromagnetic coil generates a magnetic field which applies a driving force on the magnetic particle sufficient to overcome adhesive forces exhibited between the probe tip and specimen. The atomic force microscope includes two independently displaceable piezo elements operable along a Z-axis. A controller drives the first Z-axis piezo element to provide a controlled approach between the probe tip and specimen up to a point of contact between the probe tip and specimen. The controller then drives the first Z-axis piezo element to withdraw the cantilever from the specimen. The controller also activates the pulse release system which drives the probe tip away from the specimen during withdrawal. Following withdrawal, the controller adjusts the height of the second Z-axis piezo element to maintain a substantially constant approach distance between successive samples.

Performance testing of lidar receivers

NASA Technical Reports Server (NTRS)

Shams, M. Y.

1986-01-01

In addition to the considerations about the different types of noise sources, dynamic range, and linearity of a lidar receiver, one requires information about the pulse shape retaining capabilities of the receiver. For this purpose, relatively precise information about the height resolution as well as the recovery time of the receiver, due both to large transients and to fast changes in the received signal, is required. As more and more analog receivers using fast analog to digital converters and transient recorders will be used in the future lidar systems, methods to test these devices are essential. The method proposed for this purpose is shown. Tests were carried out using LCW-10, LT-20, and FTVR-2 as optical parts of the optical pulse generator circuits. A commercial optical receiver, LNOR, and a transient recorder, VK 220-4, were parts of the receiver system.

The interaction of pulsed eddy current with metal surface crack for various coils

NASA Astrophysics Data System (ADS)

Yang, Hung-Chi; Tai, Cheng-Chi

2002-05-01

We study the interaction of pulsed eddy current (PEC) with metal surface cracks using various coils that have different geometric sizes. In the previous work, we have showed that the PEC technique can be used to inspect electrical-discharge-machined (EDM) notches with depth from 0.5 mm to 9 mm. The results showed that the relationship between PEC signals and crack depth is obvious. In this work, we further try a series of coils with different radii, heights, turns and shapes. We will discuss the effects of these coil parameters on the PEC signal. Some other critical problems of PEC measurements such as signal drift that caused by heating effect of coil currents will be studied. We also show more experiments on fatigue cracks to demonstrate the capability of PEC technique for cracks inspection.

DESCANT and β-delayed neutron measurements at TRIUMF

NASA Astrophysics Data System (ADS)

Bildstein, V.; Garrett, P. E.; Ashley, S. F.; Ball, G. C.; Bianco, L.; Bandyopadhyay, D.; Bangay, J.; Crider, B. P.; Demand, G.; Deng, G.; Dillmann, I.; Finlay, A.; Garnsworthy, A. B.; Hackman, G.; Hadinia, B.; Krücken, R.; Leach, K. G.; Martin, J.-P.; McEllistrem, M. T.; Pearson, C. J.; Peters, E. E.; Prados-Estévez, F. M.; Radich, A.; Sarazin, F.; Sumithrarachchi, C.; Svensson, C. E.; Vanhoy, J. R.; Wong, J.; Yates, S. W.

2015-05-01

The DESCANT array (Deuterated Scintillator Array for Neutron Tagging) consists of up to 70 detectors, each filled with approximately 2 liters of deuterated benzene. This scintillator material o_ers pulse-shape discrimination (PSD) capabilities to distinguish between neutrons and γ-rays interacting with the scintillator material. In addition, the anisotropic nature of n - d scattering allows for the determination of the neutron energy spectrum directly from the pulse height spectrum, complementing the traditional time-of-flight (ToF) information. DESCANT can be coupled either to the TIGRESS (TRIUMF-ISAC Gamma-Ray Escape Suppressed Spectrometer) γ-ray spectrometer [1] located in the ISAC-II [2] hall of TRIUMF for in-beam experiments, or to the GRIFFIN (Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei) γ-ray spectrometer [3] located in the ISAC-I hall of TRIUMF for decay spectroscopy experiments.

Delta II ICESat-2 Booster Arrival

NASA Image and Video Library

2018-03-09

A United Launch Alliance Delta II booster arrives at NASA's Building 836, the Spacecraft Labs Telemetry Station at Vandenberg Air Force Base in California. It will be offloaded and begin preliminary checkouts and preflight processing for launch of the agency's Ice, Cloud and land Elevation Satellite-2, or ICESat-2. Liftoff from Space Launch Complex-2 at Vandenberg is scheduled for Sept. 12, 2018, and will be the last for the venerable Delta II rocket. Once in orbit, the satellite is designed to measure the height of a changing Earth, one laser pulse at a time, 10,000 laser pulses a second. The satellite will carry a single instrument, the Advanced Topographic Laser Altimeter System. ICESat-2 will help scientists investigate why, and how much, Earth's frozen and icy areas are changing. These area make up Earth's the cryosphere.

Delta II ICESat-2 Booster Offload onto Transporter

NASA Image and Video Library

2018-04-16

At NASA's Building 836, the Spacecraft Labs Telemetry Station at Vandenberg Air Force Base in California, a United Launch Alliance Delta II booster has been removed from its shipping container. Preliminary checkouts and preflight processing will begin leading to launch of the agency's Ice, Cloud and land Elevation Satellite-2, or ICESat-2. Liftoff from Space Launch Complex-2 at Vandenberg is scheduled for Sept. 12, 2018, and will be the last for the venerable Delta II rocket. Once in orbit, the satellite is designed to measure the height of a changing Earth, one laser pulse at a time, 10,000 laser pulses a second. The satellite will carry a single instrument, the Advanced Topographic Laser Altimeter System. ICESat-2 will help scientists investigate why, and how much, Earth's frozen and icy areas are changing. These area make up Earth's the cryosphere.

Delta II ICESat-2 Booster Offload onto Transporter

NASA Image and Video Library

2018-04-16

A United Launch Alliance Delta II booster arrives at NASA's Building 836, the Spacecraft Labs Telemetry Station at Vandenberg Air Force Base in California. It will be offloaded and begin preliminary checkouts and preflight processing for launch of the agency's Ice, Cloud and land Elevation Satellite-2, or ICESat-2. Liftoff from Space Launch Complex-2 at Vandenberg is scheduled for Sept. 12, 2018, and will be the last for the venerable Delta II rocket. Once in orbit, the satellite is designed to measure the height of a changing Earth, one laser pulse at a time, 10,000 laser pulses a second. The satellite will carry a single instrument, the Advanced Topographic Laser Altimeter System. ICESat-2 will help scientists investigate why, and how much, Earth's frozen and icy areas are changing. These area make up Earth's the cryosphere.

Comparing helicopter-borne profiling radar with airborne laser scanner data for forest structure estimation.

NASA Astrophysics Data System (ADS)

Piermattei, Livia; Hollaus, Markus; Pfeifer, Norbert; Chen, Yuwei; Karjalainen, Mika; Hakala, Teemu; Hyyppä, Juha; Wagner, Wolfgang

2017-04-01

Forests are complex ecosystems that show substantial variation with respect to climate, management regime, stand history, disturbance, and needs of local communities. The dynamic processes of growth and disturbance are reflected in the structural components of forests that include the canopy vertical structure and geometry (e.g. size, height, and form), tree position and species diversity. Current remote-sensing systems to measure forest structural attributes include passive optical sensors and active sensors. The technological capabilities of active remote sensing like the ability to penetrate the vegetation and provide information about its vertical structure has promoted an extensive use of LiDAR (Light Detection And Ranging) and radar (RAdio Detection And Ranging) system over the last 20 years. LiDAR measurements from aircraft (airborne laser scanning, ALS) currently represents the primary data source for three-dimensional information on forest vertical structure. Contrary, despite the potential of radar remote sensing, their use is not yet established in forest monitoring. In order to better understand the interaction of pulsed radar with the forest canopy, and to increase the feasibility of this system, the Finnish Geospatial Research Institute has developed a helicopter-borne profiling radar system, called TomoRadar. TomoRadar is capable of recording a canopy-penetrating profile of forests. To georeference the radar measurements the system was equipped with a global navigation satellite system and an inertial measurement unit with a centimeter level accuracy of the flight trajectory. The TomoRadar operates at Ku-band, (wave lengths λ 1.5cm) with two separated parabolic antennas providing co- and cross-polarization modes. The purpose of this work is to investigate the capability of the TomoRadar system, for estimating the forest vertical profile, terrain topography and tree height. We analysed 600 m TomoRadar crosspolarized (i.e. horizontal - vertical) profile, acquired in October 2016 over a boreal test site in Evo, Finland. The intensity of the reflected backscatter energy was used to measure the height canopy distribution within an individual footprint. As the intensity of the backscatter energy from the ground is exceeding the intensity from vegetation, the estimation of canopy height and the forest structure were based on i) a threshold between canopy and ground and ii) a peak analysis of the backscattering profile. ALS data collected simultaneously was used to validate the TomoRadar results (i.e. canopy height) and to obtain elevation ground truth. The first results show a high agreement between ALS and TomoRadar derived canopy heights. The derived knowledge about the energy distribution within the canopy height profile leads to an increased understanding of the interactions between the radar signal and the forest canopy and will support optimization of future radar systems with respect to forest structure observation.

Deriving depth-dependent light escape efficiency and optical Swank factor from measured pulse height spectra of scintillators.

PubMed

Howansky, Adrian; Peng, Boyu; Lubinsky, Anthony R; Zhao, Wei

2017-03-01

Pulse height spectroscopy has been used by investigators to deduce the imaging properties of scintillators. Pulse height spectra (PHS) are used to compute the Swank factor, which describes the variation in scintillator light output per x-ray interaction. The spread in PHS measured below the K-edge is related to the optical component of the Swank factor, i.e., variations in light escape efficiency from different depths of x-ray interaction in the scintillator, denoted ε¯(z). Optimizing scintillators for medical imaging applications requires understanding of these optical properties, as they determine tradeoffs between parameters such as x-ray absorption, light yield, and spatial resolution. This work develops a model for PHS acquisition such that the effect of measurement uncertainty can be removed. This method allows ε¯(z) to be quantified on an absolute scale and permits more accurate estimation of the optical Swank factor of scintillators. The pulse height spectroscopy acquisition chain was modeled as a linear system of stochastic gain stages. Analytical expressions were derived for signal and noise propagation through the PHS chain, accounting for deterministic and stochastic aspects of x-ray absorption, scintillation, and light detection with a photomultiplier tube. The derived expressions were used to calculate PHS of thallium-doped cesium iodide (CsI) scintillators using parameters that were measured, calculated, or known from literature. PHS were measured at 25 and 32 keV of CsI samples designed with an optically reflective or absorptive backing, with or without a fiber-optic faceplate (FOP), and with thicknesses ranging from 150-1000 μm. Measured PHS were compared with calculated PHS, then light escape model parameters were varied until measured and modeled results reached agreement. Resulting estimates of ε¯(z) were used to calculate each scintillator's optical Swank factor. For scintillators of the same optical design, only minor differences in light escape efficiency were observed between samples with different thickness. As thickness increased, escape efficiency decreased by up to 20% for interactions furthest away from light collection. Optical design (i.e., backing and FOP) predominantly affected the magnitude and relative variation in ε¯(z). Depending on interaction depth and scintillator thickness, samples with an absorptive backing and FOP were estimated to yield 4.1-13.4 photons/keV. Samples with a reflective backing and FOP yielded 10.4-18.4 keV -1 , while those with a reflective backing and no FOP yielded 29.5-52.0 keV -1 . Optical Swank factors were approximately 0.9 and near-unity in samples featuring an absorptive or reflective backing, respectively. This work uses a modeling approach to remove the noise introduced by the measurement apparatus from measured PHS. This method allows absolute quantification of ε¯(z) and more accurate estimation of the optical Swank factor of scintillators. The method was applied to CsI scintillators with different thickness and optical design, and determined that optical design more strongly affects ε¯(z) and Swank factor than differences in CsI thickness. Despite large variations in ε¯(z) between optical designs, the Swank factor of all evaluated samples is above 0.9. Information provided by this methodology can help validate Monte Carlo simulations of structured CsI and optimize scintillator design for x-ray imaging applications. © 2016 American Association of Physicists in Medicine.

Deriving depth-dependent light escape efficiency and optical Swank factor from measured pulse height spectra of scintillators

PubMed Central

Howansky, Adrian; Peng, Boyu; Lubinsky, Anthony R.; Zhao, Wei

2017-01-01

Purpose Pulse height spectroscopy has been used by investigators to deduce the imaging properties of scintillators. Pulse height spectra (PHS) are used to compute the Swank factor, which describes the variation in scintillator light output per x-ray interaction. The spread in PHS measured below the K-edge is related to the optical component of the Swank factor, i.e. variations in light escape efficiency from different depths of x-ray interaction in the scintillator, denoted ε̄(z). Optimizing scintillators for medical imaging applications requires understanding of these optical properties, as they determine tradeoffs between parameters such as x-ray absorption, light yield, and spatial resolution. This work develops a model for PHS acquisition such that the effect of measurement uncertainty can be removed. This method allows ε̄(z) to be quantified on an absolute scale and permits more accurate estimation of the optical Swank factor of scintillators. Methods The pulse height spectroscopy acquisition chain was modeled as a linear system of stochastic gain stages. Analytical expressions were derived for signal and noise propagation through the PHS chain, accounting for deterministic and stochastic aspects of x-ray absorption, scintillation, and light detection with a photomultiplier tube. The derived expressions were used to calculate PHS of thallium-doped cesium iodide (CsI) scintillators using parameters that were measured, calculated, or known from literature. PHS were measured at 25 and 32 keV of CsI samples designed with an optically-reflective or absorptive backing, with or without a fiber-optic faceplate (FOP), and with thicknesses ranging from 150–1000 μm. Measured PHS were compared with calculated PHS, then light escape model parameters were varied until measured and modeled results reached agreement. Resulting estimates of ε̄(z) were used to calculate each scintillator’s optical Swank factor. Results For scintillators of the same optical design, only minor differences in light escape efficiency were observed between samples with different thickness. As thickness increased, escape efficiency decreased by up to 20% for interactions furthest away from light collection. Optical design (i.e. backing and FOP) predominantly affected the magnitude and relative variation in ε̄(z). Depending on interaction depth and scintillator thickness, samples with an absorptive backing and FOP were estimated to yield 4.1–13.4 photons/keV. Samples with a reflective backing and FOP yielded 10.4–18.4 keV−1, while those with a reflective backing and no FOP yielded 29.5–52.0 keV−1. Optical Swank factors were approximately 0.9 and near-unity in samples featuring an absorptive or reflective backing, respectively. Conclusions This work uses a modeling approach to remove the noise introduced by the measurement apparatus from measured PHS. This method allows absolute quantification of ε̄(z) and more accurate estimation of the optical Swank factor of scintillators. The method was applied to CsI scintillators with different thickness and optical design, and determined that optical design more strongly affects ε̄(z) and Swank factor than differences in CsI thickness. Despite large variations in ε̄(z) between optical designs, the Swank factor of all evaluated samples is above 0.9. Information provided by this methodology can help validate Monte Carlo simulations of structured CsI and optimize scintillator design for x-ray imaging applications. PMID:28039881

3D laser printing by ultra-short laser pulses for micro-optical applications: towards telecom wavelengths

NASA Astrophysics Data System (ADS)

Ryu, Meguya; Mizeikis, Vygantas; Morikawa, Junko; Magallanes, Hernando; Brasselet, Etienne; Varapnickas, Simonas; Malinauskas, Mangirdas; Juodkazis, Saulius

2017-08-01

Three dimensional (3D) fast (< 0.5 hour) printing of micro-optical elements down to sub-wavelength resolution over 100 μm footprint areas using femtosecond (fs-)laser oscillator is presented. Using sub-1 nJ pulse energies, optical vortex generators made of polymerised grating segments with an azimuthally changing orientation have been fabricated in SZ2080 resist; width of polymerised rods was 150 nm and period 0.6-1 μm. Detailed phase retardance analysis was carried out manually with Berek compensator (under a white light illumination) and using an equivalent principle by an automated Abrio implementation at 546 nm. Direct experimental measurements of retardance was required since the period of the grating was comparable (or larger) than the wavelength of visible light. By gold sputtering, transmissive optical vortex generators were turned into reflective ones with augmented retardance, Δn × h defined by the form birefringence, Δn, and the height h = 2d where d is the thickness of the polymerised structure. Retardance reached 315 nm as measured with Berek compensator at visible wavelengths. Birefringent phase delays of π (or λ/2 in wavelength) required for high purity vortex generators can be made based on the proposed approach. Optical vortex generators for telecom wavelengths with sub-wavelength patterns of azimuthally oriented gratings are amenable by direct laser polymerisation.

[Progress in genetic research of human height].

PubMed

Chen, Kaixu; Wang, Weilan; Zhang, Fuchun; Zheng, Xiufen

2015-08-01

It is well known that both environmental and genetic factors contribute to adult height variation in general population. However, heritability studies have shown that the variation in height is more affected by genetic factors. Height is a typical polygenic trait which has been studied by traditional linkage analysis and association analysis to identify common DNA sequence variation associated with height, but progress has been slow. More recently, with the development of genotyping and DNA sequencing technologies, tremendous achievements have been made in genetic research of human height. Hundreds of single nucleotide polymorphisms (SNPs) associated with human height have been identified and validated with the application of genome-wide association studies (GWAS) methodology, which deepens our understanding of the genetics of human growth and development and also provides theoretic basis and reference for studying other complex human traits. In this review, we summarize recent progress in genetic research of human height and discuss problems and prospects in this research area which may provide some insights into future genetic studies of human height.

Methods of Optimal Control of Laser-Plasma Instabilities Using Spike Trains of Uneven Duration and Delay (STUD Pulses)

NASA Astrophysics Data System (ADS)

Afeyan, Bedros

2013-10-01

We have recently introduced and extensively studied a new adaptive method of LPI control. It promises to extend the effectiveness of laser as inertial fusion drivers by allowing active control of stimulated Raman and Brillouin scattering and crossed beam energy transfer. It breaks multi-nanosecond pulses into a series of picosecond (ps) time scale spikes with comparable gaps in between. The height and width of each spike as well as their separations are optimization parameters. In addition, the spatial speckle patterns are changed after a number of successive spikes as needed (from every spike to never). The combination of these parameters allows the taming of parametric instabilities to conform to any desired reduced reflectivity profile, within the bounds of the performance limitations of the lasers. Instead of pulse shaping on hydrodynamical time scales, far faster (from 1 ps to 10 ps) modulations of the laser profile will be needed to implement the STUD pulse program for full LPI control. We will show theoretical and computational evidence for the effectiveness of the STUD pulse program to control LPI. The physics of why STUD pulses work and how optimization can be implemented efficiently using statistical nonlinear optical models and techniques will be explained. We will also discuss a novel diagnostic system employing STUD pulses that will allow the boosted measurement of velocity distribution function slopes on a ps time scale in the small crossing volume of a pump and a probe beam. Various regimes from weak to strong coupling and weak to strong damping will be treated. Novel pulse modulation schemes and diagnostic tools based on time-lenses used in both microscope and telescope modes will be suggested for the execution of the STUD pule program. Work Supported by the DOE NNSA-OFES Joint Program on HEDLP and DOE OFES SBIR Phase I Grants.

Analysis of multiple pulse NMR in solids. III

NASA Technical Reports Server (NTRS)

Burum, D. P.; Rhim, W. K.

1979-01-01

The paper introduces principles which greatly simplify the process of designing and analyzing compound pulse cycles. These principles are demonstrated by applying them to the design and analysis of several cycles, including a 52-pulse cycle; this pulse cycle combines six different REV-8 cycles and has substantially more resolving power than previously available techniques. Also, a new 24-pulse cycle is introduced which combines three different REV-8 cycles and has a resolving ability equivalent to that of the 52-pulse cycle. The principle of pulse-cycle decoupling provides a method for systematically combining pulse groups into compound cycles in order to achieve enhanced performance. This method is illustrated by a logical development from the two-pulse solid echo sequence to the WAHUHA (Waugh et al., 1968), the REV-8, and the new 24-pulse and 52-pulse cycles, along with the 14-pulse and 12-pulse cycles. Proton chemical shift tensor components for several organic solids, measured by using the 52-pulse cycle, are reported without detailed discussion.

K-mean clustering algorithm for processing signals from compound semiconductor detectors

NASA Astrophysics Data System (ADS)

Tada, Tsutomu; Hitomi, Keitaro; Wu, Yan; Kim, Seong-Yun; Yamazaki, Hiromichi; Ishii, Keizo

2011-12-01

The K-mean clustering algorithm was employed for processing signal waveforms from TlBr detectors. The signal waveforms were classified based on its shape reflecting the charge collection process in the detector. The classified signal waveforms were processed individually to suppress the pulse height variation of signals due to the charge collection loss. The obtained energy resolution of a 137Cs spectrum measured with a 0.5 mm thick TlBr detector was 1.3% FWHM by employing 500 clusters.

Portable neutron spectrometer and dosimeter

DOEpatents

Waechter, D.A.; Erkkila, B.H.; Vasilik, D.G.

The disclosure relates to a battery operated neutron spectrometer/dosimeter utilizing a microprocessor, a built-in tissue equivalent LET neutron detector, and a 128-channel pulse height analyzer with integral liquid crystal display. The apparatus calculates doses and dose rates from neutrons incident on the detector and displays a spectrum of rad or rem as a function of keV per micron of equivalent tissue and also calculates and displays accumulated dose in millirads and millirem as well as neutron dose rates in millirads per hour and millirem per hour.

Some gamma-ray shielding measurements made at altitudes greater than 115000 feet using large Ge(Li) detectors

NASA Technical Reports Server (NTRS)

Chapman, G. T.; Cumby, R. P.; Gibbons, J. H.; Macklin, R. L.; Parker, H. W.

1972-01-01

A series of balloon-flight experiments at altitudes greater than 115,000 feet were conducted to gain information relative to the use of composite shields (passive and/or active) for shielding large-volume, lithium-drifted, germanium (Ge(Li)) detectors used in gamma-ray spectrometers. Data showing the pulse-height spectra of the environmental gamma radiation as measured at 5.3 and 3.8 gms sq cm residual atmosphere with an unshielded diode detector are also presented.

Portable neutron spectrometer and dosimeter

DOEpatents

Waechter, David A.; Erkkila, Bruce H.; Vasilik, Dennis G.

1985-01-01

The disclosure relates to a battery operated neutron spectrometer/dosimeter utilizing a microprocessor, a built-in tissue equivalent LET neutron detector, and a 128-channel pulse height analyzer with integral liquid crystal display. The apparatus calculates doses and dose rates from neutrons incident on the detector and displays a spectrum of rad or rem as a function of keV per micron of equivalent tissue and also calculates and displays accumulated dose in millirads and millirem as well as neutron dose rates in millirads per hour and millirem per hour.

Low power laser trigger switching of a solid insulated spark gap.

PubMed

Guenther, A H; Copeland, R P; Bettis, J R

1979-11-01

The feasibility of reliably triggering solid dielectric insulated spark gaps by low power ( approximately 6 MW) lasers has been demonstrated. Breakdown of 10-mil Lexan dielectric sheets stressed to 70 kV was initiated by a focused 6 MW, Nd in YAG laser emitting 40 mJ in a pulse 6 ns wide at the half-peak intensity height. Delays achieved were in the tens of ns. Slight increases in laser power or electrical stress should produce shorter delays (<10 ns) and subnanosecond jitter.

Maintenance Welding in Nuclear Power Plants/III, Conference Proceedings Held at Knoxville, Tennessee on 6-8 November 1985

DTIC Science & Technology

1985-11-06

Mongiat, S. Kumar and K.K. Subbayya ALTERNATXVES TO ONE-HALF BEAD REPAIR TECHNIQUE ( GTAW ); ................................... 153 By P. J. Alberry...3.5.1 Welding Procedure The welding procedure used for mechanized welding of permanently installed pipes is the pulsed GTAW welding procedure with a cold...be adapted . to this system to an -’verall height of 130 mm. Because of the considerably shorter welding times, the GTAW narrow opening welling

Evaluation of the Correlation of Ramus Height, Gonial Angle, and Dental Height with Different Facial Forms in Individuals with Deep Bite Disorders

PubMed Central

Ahila, SC; Sasikala, C; Kumar, B Muthu; Tah, Rajdeep; Abinaya, K

2016-01-01

Background: Restoring the vertical dimension is a critical procedure in prosthetic dentistry. Anterior facial height has a significant impact on the length of the ramus. Patients with deep bite will exhibit a shorter lower facial height; hence, restoring the vertical dimension esthetically without altering the facial form is highly challenging. Aim: To evaluate the relationship of gonial angle, ramus height, and dental height with different facial forms. Subjects and Methods: A total of 51 subjects in all facial form aged between 20 and 40 with deep bite were randomly selected. Lateral cephalograms and facial photographs were made for each patient. Ramus height was measured on lateral cephalogram by measuring the distance from articulare to gonion. The gonial angles were calculated and anterior and posterior dental height were measured from cephalogram. Facial forms were evaluated using patient's photographs. Results: The obtained measurements were evaluated, and compared statistically with one way analysis of variance and regression correlation test. Statistical analysis revealed that there was no correlation found between the gonial angle and ramus height. Conclusion: Correlation found between the ramus height and anterior and posterior dental height in patients with deep bite disorders. The ramus height can be calculated using the formulas 46.42 + (0.095 × AD height), 46.046+ (0.123 × PD height). PMID:28480098

Evidence of seasonal variation in longitudinal growth of height in a sample of boys from Stuttgart Carlsschule, 1771-1793, using combined principal component analysis and maximum likelihood principle.

PubMed

Lehmann, A; Scheffler, Ch; Hermanussen, M

2010-02-01

Recent progress in modelling individual growth has been achieved by combining the principal component analysis and the maximum likelihood principle. This combination models growth even in incomplete sets of data and in data obtained at irregular intervals. We re-analysed late 18th century longitudinal growth of German boys from the boarding school Carlsschule in Stuttgart. The boys, aged 6-23 years, were measured at irregular 3-12 monthly intervals during the period 1771-1793. At the age of 18 years, mean height was 1652 mm, but height variation was large. The shortest boy reached 1474 mm, the tallest 1826 mm. Measured height closely paralleled modelled height, with mean difference of 4 mm, SD 7 mm. Seasonal height variation was found. Low growth rates occurred in spring and high growth rates in summer and autumn. The present study demonstrates that combining the principal component analysis and the maximum likelihood principle enables growth modelling in historic height data also. Copyright (c) 2009 Elsevier GmbH. All rights reserved.

General purpose pulse shape analysis for fast scintillators implemented in digital readout electronics

NASA Astrophysics Data System (ADS)

Asztalos, Stephen J.; Hennig, Wolfgang; Warburton, William K.

2016-01-01

Pulse shape discrimination applied to certain fast scintillators is usually performed offline. In sufficiently high-event rate environments data transfer and storage become problematic, which suggests a different analysis approach. In response, we have implemented a general purpose pulse shape analysis algorithm in the XIA Pixie-500 and Pixie-500 Express digital spectrometers. In this implementation waveforms are processed in real time, reducing the pulse characteristics to a few pulse shape analysis parameters and eliminating time-consuming waveform transfer and storage. We discuss implementation of these features, their advantages, necessary trade-offs and performance. Measurements from bench top and experimental setups using fast scintillators and XIA processors are presented.

Experimental study of flow reattachment in a single-sided sudden expansion

NASA Technical Reports Server (NTRS)

Westphal, R. V.; Johnston, J. P.; Eaton, J. K.

1984-01-01

The reattachment of a fully turbulent, two dimensional, separated shear layer downstream of a single-sided sudden expansion in a planar duct flow was examined experimentally. The importance of changing the structure of the separated shear layer on the reattachment process itself was examined. For all cases, the Reynolds number based on step height was greater than 20,000, the expansion ratio was 5/3, and the inlet boundary layer was less than one-half step height in thickness. A crucially important phase was the development of a pulsed wall probe for measurement of skin friction in the reattachment region, thus providing an unambiguous definition of the reattachment length. Quantitative features of reattachment - including streamwise development of the mean and fluctuating velocity field, pressure rise, and skin friction - were found to be similar for all cases studied when scaled by the reattachment length. A definition of the reattachment zone is proposed.

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

Bamberger, Judith A.; Piepel, Gregory F.; Enderlin, Carl W.

Understanding how uncertainty manifests itself in complex experiments is important for developing the testing protocol and interpreting the experimental results. This paper describes experimental and measurement uncertainties, and how they can depend on the order of performing experimental tests. Experiments with pulse-jet mixers in tanks at three scales were conducted to characterize the performance of transient-developing periodic flows in Newtonian slurries. Other test parameters included the simulant, solids concentration, and nozzle exit velocity. Critical suspension velocity and cloud height were the metrics used to characterize Newtonian slurry flow associated with mobilization and mixing. During testing, near-replicate and near-repeat tests weremore » conducted. The experimental results were used to quantify the combined experimental and measurement uncertainties using standard deviations and percent relative standard deviations (%RSD) The uncertainties in critical suspension velocity and cloud height tend to increase with the values of these responses. Hence, the %RSD values are the more appropriate summary measure of near-replicate testing and measurement uncertainty.« less

Ridge Minimization of Ablated Morphologies on ITO Thin Films Using Squared Quasi-Flat Top Beam

PubMed Central

Jeon, Jin-Woo; Choi, Wonsuk; Shin, Young-Gwan; Ji, Suk-Young

2018-01-01

In this study, we explore the improvements in pattern quality that was obtained with a femtosecond laser with quasi-flat top beam profiles at the ablated edge of indium tin oxide (ITO) thin films for the patterning of optoelectronic devices. To ablate the ITO thin films, a femtosecond laser is used that has a wavelength and pulse duration of 1030 nm and 190 fs, respectively. The squared quasi-flat top beam is obtained from a circular Gaussian beam using slits with varying x-y axes. Then, the patterned ITO thin films are measured using both scanning electron and atomic force microscopes. In the case of the Gaussian beam, the ridge height and width are approximately 39 nm and 1.1 μm, respectively, whereas, when the quasi-flat top beam is used, the ridge height and width are approximately 7 nm and 0.25 μm, respectively. PMID:29601515

A Global Sensitivity Analysis Method on Maximum Tsunami Wave Heights to Potential Seismic Source Parameters

NASA Astrophysics Data System (ADS)

Ren, Luchuan

2015-04-01

A Global Sensitivity Analysis Method on Maximum Tsunami Wave Heights to Potential Seismic Source Parameters Luchuan Ren, Jianwei Tian, Mingli Hong Institute of Disaster Prevention, Sanhe, Heibei Province, 065201, P.R. China It is obvious that the uncertainties of the maximum tsunami wave heights in offshore area are partly from uncertainties of the potential seismic tsunami source parameters. A global sensitivity analysis method on the maximum tsunami wave heights to the potential seismic source parameters is put forward in this paper. The tsunami wave heights are calculated by COMCOT ( the Cornell Multi-grid Coupled Tsunami Model), on the assumption that an earthquake with magnitude MW8.0 occurred at the northern fault segment along the Manila Trench and triggered a tsunami in the South China Sea. We select the simulated results of maximum tsunami wave heights at specific sites in offshore area to verify the validity of the method proposed in this paper. For ranking importance order of the uncertainties of potential seismic source parameters (the earthquake's magnitude, the focal depth, the strike angle, dip angle and slip angle etc..) in generating uncertainties of the maximum tsunami wave heights, we chose Morris method to analyze the sensitivity of the maximum tsunami wave heights to the aforementioned parameters, and give several qualitative descriptions of nonlinear or linear effects of them on the maximum tsunami wave heights. We quantitatively analyze the sensitivity of the maximum tsunami wave heights to these parameters and the interaction effects among these parameters on the maximum tsunami wave heights by means of the extended FAST method afterward. The results shows that the maximum tsunami wave heights are very sensitive to the earthquake magnitude, followed successively by the epicenter location, the strike angle and dip angle, the interactions effect between the sensitive parameters are very obvious at specific site in offshore area, and there exist differences in importance order in generating uncertainties of the maximum tsunami wave heights for same group parameters at different specific sites in offshore area. These results are helpful to deeply understand the relationship between the tsunami wave heights and the seismic tsunami source parameters. Keywords: Global sensitivity analysis; Tsunami wave height; Potential seismic tsunami source parameter; Morris method; Extended FAST method

Direct stratospheric injection of biomass burning emissions: a case study of the 2009 Australian bushfires using the NASA GISS ModelE2 composition-climate model

NASA Astrophysics Data System (ADS)

Field, Robert; From, Mike; Voulgarakis, Apostolos; Shindell, Drew; Flannigan, Mike; Bernath, Peter

2014-05-01

Direct stratospheric injection (DSI) of forest fire smoke represents a direct biogeochemical link between the land surface and stratosphere. DSI events occur regularly in the northern and southern extratropics, and have been observed across a wide range of measurements, but their fate and effects are not well understood. DSIs result from explosive, short-lived fires, and their plumes stand out from background concentrations immediately. This makes it easier to associate detected DSIs to individual fires and their estimated emissions. Because the emissions pulses are brief, chemical decay can be more clearly assessed, and because the emissions pulses are so large, a wide range of rare chemical species can be detected. Observational evidence suggests that they can persist in the stratosphere for several months, enhance ozone production, and be self-lofted to the middle stratosphere through shortwave absorption and diabatic heating. None of these phenomena have been evaluated, however, with a physical model. To that end, we are simulating the smoke plumes from the February 2009 Australia 'Black Saturday' bushfires using the NASA GISS ModelE2 composition-climate model, nudged toward horizontal winds from reanalysis. To-date, this is the best-observed DSI in the southern hemisphere. Chemical and aerosol signatures of the plume were observed in a wide array of limb and nadir satellite retrievals. Detailed estimates of fuel consumption and injection height have been made because of the severity of the fires. Uncommon among DSIs events was a large segment of the plume that entrained into the upper equatorial easterlies. Preliminary modeling results show that the relative strengths of the equatorial and extratropical plume segments are sensitive to the plume's initial injection height. This highlights the difficulty in reconciling uncertainty in the reanalysis over the Southern Hemisphere with fairly-well constrained estimates of fire location and injection height at the source.

Techniques for Analysis of DSN 64-meter Antenna Azimuth Bearing Film Height Records

NASA Technical Reports Server (NTRS)

Stevens, R.; Quach, C. T.

1983-01-01

The DSN 64-m antennas use oil pad azimuth thrust bearings. Instrumentation on the bearing pads measures the height of the oil film between the pad and the bearing runner. Techniques to analyze the film height record are developed and discussed. The analysis techniques present the unwieldy data in a compact form for assessment of bearing condition. The techniques are illustrated by analysis of a small sample of film height records from each of the three 64-m antennas. The results show the general condition of the bearings of DSS 43 and DSS 63 as good to excellent, and a DSS 14 as marginal.

Evaluation of stress distribution of implant-retained mandibular overdenture with different vertical restorative spaces: A finite element analysis

PubMed Central

Ebadian, Behnaz; Farzin, Mahmoud; Talebi, Saeid; Khodaeian, Niloufar

2012-01-01

Background: Available restorative space and bar height is an important factor in stress distribution of implant-supported overdentures. The purpose of this study was to evaluate the effect of different vertical restorative spaces and different bar heights on the stress distribution around implants by 3D finite element analysis. Materials and Methods: 3D finite element models were developed from mandibular overdentures with two implants in the interforaminal region. In these models, four different bar heights from gingival crest (0.5, 1, 1.5, 2 mm) with 15 mm occlusal plane height and three different occlusal plane heights from gingival crest (9, 12, 15 mm) with 2 mm bar height were analyzed. A vertical unilateral and a bilateral load of 150 N were applied to the central occlusal fossa of the first molar and the stress of bone around implant was analyzed by finite element analysis. Results: By increasing vertical restorative space, the maximum stress values around implants were found to be decreased in unilateral loading models but slightly increased in bilateral loading cases. By increasing bar height from gingival crest, the maximum stress values around implants were found to be increased in unilateral loading models but slightly decreased in bilateral loading cases. In unilateral loading models, maximum stress was found in a model with 9 mm occlusal plane height and 1.5 mm bar height (6.254 MPa), but in bilateral loading cases, maximum stress was found in a model with 15 mm occlusal plane height and 0.5 mm bar height (3.482 MPa). Conclusion: The reduction of bar height and increase in the thickness of acrylic resin base in implant-supported overdentures are biomechanically favorable and may result in less stress in periimplant bone. PMID:23559952

Performance verification and system integration tests of the pulse shape processor for the soft x-ray spectrometer onboard ASTRO-H

NASA Astrophysics Data System (ADS)

Takeda, Sawako; Tashiro, Makoto S.; Ishisaki, Yoshitaka; Tsujimoto, Masahiro; Seta, Hiromi; Shimoda, Yuya; Yamaguchi, Sunao; Uehara, Sho; Terada, Yukikatsu; Fujimoto, Ryuichi; Mitsuda, Kazuhisa

2014-07-01

The soft X-ray spectrometer (SXS) aboard ASTRO-H is equipped with dedicated digital signal processing units called pulse shape processors (PSPs). The X-ray microcalorimeter system SXS has 36 sensor pixels, which are operated at 50 mK to measure heat input of X-ray photons and realize an energy resolution of 7 eV FWHM in the range 0.3-12.0 keV. Front-end signal processing electronics are used to filter and amplify the electrical pulse output from the sensor and for analog-to-digital conversion. The digitized pulses from the 36 pixels are multiplexed and are sent to the PSP over low-voltage differential signaling lines. Each of two identical PSP units consists of an FPGA board, which assists the hardware logic, and two CPU boards, which assist the onboard software. The FPGA board triggers at every pixel event and stores the triggering information as a pulse waveform in the installed memory. The CPU boards read the event data to evaluate pulse heights by an optimal filtering algorithm. The evaluated X-ray photon data (including the pixel ID, energy, and arrival time information) are transferred to the satellite data recorder along with event quality information. The PSP units have been developed and tested with the engineering model (EM) and the flight model. Utilizing the EM PSP, we successfully verified the entire hardware system and the basic software design of the PSPs, including their communication capability and signal processing performance. In this paper, we show the key metrics of the EM test, such as accuracy and synchronicity of sampling clocks, event grading capability, and resultant energy resolution.

Forearm Vascular Reactivity and Arterial Stiffness in Asymptomatic Subjects from the Community

PubMed Central

Malik, A. Rauoof; Kondragunta, Venkateswarlu; Kullo, Iftikhar J.

2010-01-01

Vascular reactivity may affect the stiffness characteristics of the arterial wall. We investigated the association between forearm microcirculatory and conduit artery function and measures of arterial stiffness in 527 asymptomatic non-Hispanic white adults without known cardiovascular disease. High-resolution ultrasonography of the brachial artery (ba) was performed to assess forearm microcirculatory function (ba blood flow velocity, local shear stress, and forearm vascular resistance at rest and during reactive hyperemia) and conduit artery function (ba flow-mediated dilatation baFMD and ba nitroglycerin-mediated dilatation baNMD). Arterial stiffness was assessed by cuff-derived brachial pulse pressure and aortic pulse wave velocity (aPWV) measured by applanation tonometry. In regression analyses that adjusted for heart rate, mean arterial pressure, height, cardiovascular risk factors, and hypertension medication and statin use, higher baseline ba systolic velocity and systolic shear stress were associated with greater pulse pressure (P=0.0002 and P=0.006, respectively) and higher aPWV (each P<0.0001). During hyperemia, lower ba mean velocity and lower mean shear stress were associated with higher pulse pressure (P=0.045 and P=0.036, respectively) while both systolic and mean velocity (P<0.0001 and P=0.002, respectively) and systolic and mean shear stress (P<0.0001 and P=0.003, respectively) were inversely associated with aPWV. baFMD was not associated with pulse pressure but was inversely associated with aPWV (P=0.011). baNMD was inversely associated with pulse pressure (P=0.0002) and aPWV (P=0.008). Our findings demonstrate that impaired forearm microvascular function (in the form of elevated resting blood flow velocity and impaired flow reserve) and impaired brachial artery reactivity are associated with increased arterial stiffness. PMID:18426995

Arterial stiffness estimation based photoplethysmographic pulse wave analysis

NASA Astrophysics Data System (ADS)

Huotari, Matti; Maatta, Kari; Kostamovaara, Juha

2010-11-01

Arterial stiffness is one of the indices of vascular healthiness. It is based on pulse wave analysis. In the case we decompose the pulse waveform for the estimation and determination of arterial elasticity. Firstly, optically measured with photoplethysmograph and then investigating means by four lognormal pulse waveforms for which we can find very good fit between the original and summed decomposed pulse wave. Several studies have demonstrated that these kinds of measures predict cardiovascular events. While dynamic factors, e.g., arterial stiffness, depend on fixed structural features of the vascular wall. Arterial stiffness is estimated based on pulse wave decomposition analysis in the radial and tibial arteries. Elucidation of the precise relationship between endothelial function and vascular stiffness awaits still further study.

On the sea-state bias of the Geosat altimeter

NASA Technical Reports Server (NTRS)

Ray, Richard D.; Koblinsky, Chester J.

1991-01-01

The sea-state bias in a satellite altimeter's range measurement is caused by the influence of ocean waves on the radar return pulse; it results in an estimate of sea level that is too low according to some function of the wave height. This bias is here estimated for Geosat by correlating collinear differences of altimetric sea-surface heights with collinear differences of significant wave heights (H1/3). Corrections for satellite orbit error are estimated simultaneously with the sea-state bias. Based on twenty 17-day repeat cycles of the Geosat Exact Repeat Mission, the solution for the sea-state bias is 2.6 + or - 0.2 percent of H1/3. The least-squares residuals, however, show a correlation with wind speed U, so the traditional model of the bias has been supplemented with a second term: H1/3 + alpha-2H1/3U. This second term produces a small, but statistically significant, reduction in variance of the residuals. Both systematic and random errors in H1/3 and U tend to bias the estimates of alpha-1 and alpha-2, which complicates comparisons of the results with ground-based measurements of the sea-state bias.

On the sea-state bias of the Geosat altimeter

NASA Astrophysics Data System (ADS)

Ray, Richard D.; Koblinsky, Chester J.

1991-06-01

The sea-state bias in a satellite altimeter's range measurement is caused by the influence of ocean waves on the radar return pulse; it results in an estimate of sea level that is too low according to some function of the wave height. This bias is here estimated for Geosat by correlating collinear differences of altimetric sea-surface heights with collinear differences of significant wave heights (H1/3). Corrections for satellite orbit error are estimated simultaneously with the sea-state bias. Based on twenty 17-day repeat cycles of the Geosat Exact Repeat Mission, the solution for the sea-state bias is 2.6 + or - 0.2 percent of H1/3. The least-squares residuals, however, show a correlation with wind speed U, so the traditional model of the bias has been supplemented with a second term: H1/3 + alpha-2H1/3U. This second term produces a small, but statistically significant, reduction in variance of the residuals. Both systematic and random errors in H1/3 and U tend to bias the estimates of alpha-1 and alpha-2, which complicates comparisons of the results with ground-based measurements of the sea-state bias.

Determining the source of strong LF/VLF TIPP events: Implications for association with NPBPs and NNBPs

NASA Astrophysics Data System (ADS)

Zuelsdorf, R. S.; Franz, R. C.; Strangeway, R. J.; Russell, C. T.

2000-08-01

Transionospheric pulse pairs (TIPPs) as detected by the Blackbeard VHF radio instrument onboard the ALEXIS satellite have been shown to correlate with pulses detected by stations in the National Lightning Detection Network (NLDN). The short peak-to-zero time of these NLDN-detected pulses (<10 μs) are indicative of interior cloud processes, as opposed to the longer pulses associated with cloud-to-ground discharges. TIPPs are most probably generated by the same discharge responsible for narrow bipolar pulses (NBPs), which have been detected on the ground but are also believed to be generated entirely inside the cloud. Here we report on five TIPPs detected by Blackbeard that are correlated with cloud-generated pulses detected by multiple stations in the NLDN during powerful storms. Previously, a maximum of two stations at a time showed such a correlation. Given the greater area of detection, these pulses radiate more powerfully in the LF/VLF frequencies than those previously detected as TIPPs by Blackbeard. We are able to place the sources of the TIPPs in Hurricane Fausto off the coast of Mexico, and in a remnant of the same storm eight days later over Texas. The heights of the sources are higher than those previously determined for TIPPs. The higher altitudes and the greater power of the TIPP-correlating signals may be related to the intensity of the storms. Two of these five TIPPs were also correlated with the ground detection of HF signals, and the TIPPs and HF signals were determined to originate from the same source region. These HF signals are similar to those previously recorded with the field change signature of narrow positive bipolar pulses (NPBPs), but we find that both polarities are detected, four out of the five being negative. This indicates that TIPPs correlate with narrow negative bipolar pulses (NNBPs) as well as NPBPs. The detection of NNBPs, which has previously been much rarer than NPBPs, may also be related to the intensity of the storms and the resultant higher-altitude sources.

Cs2LiLa(Br,Cl)6 Crystals for Nuclear Security Applications

NASA Astrophysics Data System (ADS)

Hawrami, R.; Pandian, L. Soundara; Ariesanti, E.; Glodo, J.; Finkelstein, J.; Tower, J.; Shah, K.

2016-04-01

Properties of dual-mode scintillation detectors based on CLLBC crystals are reported. Energy resolution and light yield are measured at 2.9% (FWHM) at 662 keV and 45000 photons/MeV, respectively, for a 1-in-diameter and 1-in-long crystal. With less than 2% variation in light yield as a function of energy, CLLBC has better proportionality than LaBr3 and NaI:Tl. Neutron peak resulting from reactions with neutrons emitted by 252Cf (moderated) is measured at a gamma energy equivalent of 3.1 MeVee (electron energy equivalent), making pulse height discrimination between gamma-rays and neutrons easy. The material is also of effective pulse shape discrimination. The figure-of-merit for discrimination of gamma rays and thermal neutrons in CLLBC can be as high as 3.2, which is comparable to that of CLYC.

Conceptual study of Earth observation missions with a space-borne laser scanner

NASA Astrophysics Data System (ADS)

Kobayashi, Takashi; Sato, Yohei; Yamakawa, Shiro

2017-11-01

The Japan Aerospace Exploration Agency (JAXA) has started a conceptual study of earth observation missions with a space-borne laser scanner (GLS, as Global Laser Scanner). Laser scanners are systems which transmit intense pulsed laser light to the ground from an airplane or a satellite, receive the scattered light, and measure the distance to the surface from the round-trip delay time of the pulse. With scanning mechanisms, GLS can obtain high-accuracy three-dimensional (3D) information from all over the world. High-accuracy 3D information is quite useful in various areas. Currently, following applications are considered. 1. Observation of tree heights to estimate the biomass quantity. 2. Making the global elevation map with high resolution. 3. Observation of ice-sheets. This paper aims at reporting the present state of our conceptual study of the GLS. A prospective performance of the GLS for earth observation missions mentioned above.

Delta II ICESat-2 Booster Transport

NASA Image and Video Library

2018-04-17

At Vandenberg Air Force Base in California, on Tuesday, April 17, 2018, a United Launch Alliance (ULA) Delta II booster is transported to Space Launch Complex-2 where it will launch NASA's Ice, Cloud and land Elevation Satellite-2, or ICESat-2, satellite. This will be the last flight for the venerable Delta II rocket. ICESat-2, which is being built and tested by Orbital ATK in Gilbert, Arizona, will carry a single instrument called the Advanced Topographic Laser Altimeter System, or ATLAS. The ATLAS instrument is being built and tested at NASA’s Goddard Space Flight Center in Greenbelt Maryland. Once in orbit, the satellite is designed to measure the height of a changing Earth, one laser pulse at a time, 10,000 laser pulses a second. ICESat-2 will help scientists investigate why, and how much, Earth’s frozen and icy areas, called the cryosphere, are changing.

Delta II ICESat-2 Booster Transport

NASA Image and Video Library

2018-04-17

At NASA's Building 836, the Spacecraft Labs Telemetry Station at Vandenberg Air Force Base in California, on Tuesday, April 17, 2018, a United Launch Alliance (ULA) Delta II booster is transported to Space Launch Complex-2 where it will launch NASA's Ice, Cloud and land Elevation Satellite-2, or ICESat-2, satellite. This will be the last flight for the venerable Delta II rocket. ICESat-2, which is being built and tested by Orbital ATK in Gilbert, Arizona, will carry a single instrument called the Advanced Topographic Laser Altimeter System, or ATLAS. The ATLAS instrument is being built and tested at NASA’s Goddard Space Flight Center in Greenbelt Maryland. Once in orbit, the satellite is designed to measure the height of a changing Earth, one laser pulse at a time, 10,000 laser pulses a second. ICESat-2 will help scientists investigate why, and how much, Earth’s frozen and icy areas, called the cryosphere, are changing.

Delta II ICESat-2 Booster Transport

NASA Image and Video Library

2018-04-17

At Vandenberg Air Force Base in California, on Tuesday, April 17, 2018, a United Launch Alliance (ULA) Delta II booster arrives at Space Launch Complex-2 where it will launch NASA's Ice, Cloud and land Elevation Satellite-2, or ICESat-2, satellite. This will be the last flight for the venerable Delta II rocket. ICESat-2, which is being built and tested by Orbital ATK in Gilbert, Arizona, will carry a single instrument called the Advanced Topographic Laser Altimeter System, or ATLAS. The ATLAS instrument is being built and tested at NASA’s Goddard Space Flight Center in Greenbelt Maryland. Once in orbit, the satellite is designed to measure the height of a changing Earth, one laser pulse at a time, 10,000 laser pulses a second. ICESat-2 will help scientists investigate why, and how much, Earth’s frozen and icy areas, called the cryosphere, are changing.

Delta II ICESat-2 Booster Offload onto Transporter

NASA Image and Video Library

2018-04-16

At NASA's Building 836, the Spacecraft Labs Telemetry Station at Vandenberg Air Force Base in California, a United Launch Alliance Delta II booster is removed from its shipping container. After it is offloaded, preliminary checkouts and preflight processing will begin leading to launch of the agency's Ice, Cloud and land Elevation Satellite-2, or ICESat-2. Liftoff from Space Launch Complex-2 at Vandenberg is scheduled for Sept. 12, 2018, and will be the last for the venerable Delta II rocket. Once in orbit, the satellite is designed to measure the height of a changing Earth, one laser pulse at a time, 10,000 laser pulses a second. The satellite will carry a single instrument, the Advanced Topographic Laser Altimeter System. ICESat-2 will help scientists investigate why, and how much, Earth's frozen and icy areas are changing. These area make up Earth's the cryosphere.

Micro pulse lidar

NASA Technical Reports Server (NTRS)

Spinhirne, James D.

1993-01-01

An eye safe, compact, solid state lidar for profiling atmospheric cloud and aerosol scattering has been demonstrated. The transmitter of the micropulse lidar is a diode pumped micro-J pulse energy, high repetition rate Nd:YLF laser. Eye safety is obtained through beam expansion. The receiver employs a photon counting solid state Geiger mode avalanche photodiode detector. Data acquisition is by a single card multichannel scaler. Daytime background induced quantum noise is controlled by a narrow receiver field-of-view and a narrow bandwidth temperature controlled interference filter. Dynamic range of the signal is limited by optical geometric signal compression. Signal simulations and initial atmospheric measurements indicate that systems built on the micropulse lidar concept are capable of detecting and profiling all significant cloud and aerosol scattering through the troposphere and into the stratosphere. The intended applications are scientific studies and environmental monitoring which require full time, unattended measurements of the cloud and aerosol height structure.

Laser-pulse compression in a collisional plasma under weak-relativistic ponderomotive nonlinearity

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

Singh, Mamta; Gupta, D. N., E-mail: dngupta@physics.du.ac.in

We present theory and numerical analysis which demonstrate laser-pulse compression in a collisional plasma under the weak-relativistic ponderomotive nonlinearity. Plasma equilibrium density is modified due to the ohmic heating of electrons, the collisions, and the weak relativistic-ponderomotive force during the interaction of a laser pulse with plasmas. First, within one-dimensional analysis, the longitudinal self-compression mechanism is discussed. Three-dimensional analysis (spatiotemporal) of laser pulse propagation is also investigated by coupling the self-compression with the self-focusing. In the regime in which the laser becomes self-focused due to the weak relativistic-ponderomotive nonlinearity, we provide results for enhanced pulse compression. The results show thatmore » the matched interplay between self-focusing and self-compression can improve significantly the temporal profile of the compressed pulse. Enhanced pulse compression can be achieved by optimizing and selecting the parameters such as collision frequency, ion-temperature, and laser intensity.« less

Analytical Characterization on Pulse Propagation in a Semiconductor Optical Amplifier Based on Homotopy Analysis Method

NASA Astrophysics Data System (ADS)

Jia, Xiaofei

2018-06-01

Starting from the basic equations describing the evolution of the carriers and photons inside a semiconductor optical amplifier (SOA), the equation governing pulse propagation in the SOA is derived. By employing homotopy analysis method (HAM), a series solution for the output pulse by the SOA is obtained, which can effectively characterize the temporal features of the nonlinear process during the pulse propagation inside the SOA. Moreover, the analytical solution is compared with numerical simulations with a good agreement. The theoretical results will benefit the future analysis of other problems related to the pulse propagation in the SOA.

Spatiotemporal Monte Carlo transport methods in x-ray semiconductor detectors: application to pulse-height spectroscopy in a-Se.

PubMed

Fang, Yuan; Badal, Andreu; Allec, Nicholas; Karim, Karim S; Badano, Aldo

2012-01-01

The authors describe a detailed Monte Carlo (MC) method for the coupled transport of ionizing particles and charge carriers in amorphous selenium (a-Se) semiconductor x-ray detectors, and model the effect of statistical variations on the detected signal. A detailed transport code was developed for modeling the signal formation process in semiconductor x-ray detectors. The charge transport routines include three-dimensional spatial and temporal models of electron-hole pair transport taking into account recombination and trapping. Many electron-hole pairs are created simultaneously in bursts from energy deposition events. Carrier transport processes include drift due to external field and Coulombic interactions, and diffusion due to Brownian motion. Pulse-height spectra (PHS) have been simulated with different transport conditions for a range of monoenergetic incident x-ray energies and mammography radiation beam qualities. Two methods for calculating Swank factors from simulated PHS are shown, one using the entire PHS distribution, and the other using the photopeak. The latter ignores contributions from Compton scattering and K-fluorescence. Comparisons differ by approximately 2% between experimental measurements and simulations. The a-Se x-ray detector PHS responses simulated in this work include three-dimensional spatial and temporal transport of electron-hole pairs. These PHS were used to calculate the Swank factor and compare it with experimental measurements. The Swank factor was shown to be a function of x-ray energy and applied electric field. Trapping and recombination models are all shown to affect the Swank factor.

Is there a highly magnetized neutron star in GX 301-2?

NASA Astrophysics Data System (ADS)

Doroshenko, V.; Santangelo, A.; Suleimanov, V.; Kreykenbohm, I.; Staubert, R.; Ferrigno, C.; Klochkov, D.

2010-06-01

We present the results of an in-depth study of the long-period X-ray pulsar GX 301-2. Using archival data of INTEGRAL, RXTE ASM, and CGRO BATSE, we study the spectral and timing properties of the source. Comparison of our timing results with previously published work reveals a secular decay of the orbital period at a rate of ≃ - 3.25 × 10-5 d yr-1, which is an order of magnitude faster than for other known systems. We argue that this is probably result either of the apsidal motion or of gravitational coupling of the matter lost by the optical companion with the neutron star, although current observations do not allow us to distinguish between those possibilities. We also propose a model to explain the observed long pulse period. We find that a very strong magnetic field B ~ 1014 G can explain the observed pulse period in the framework of existing models for torques affecting the neutron star. We show that the apparent contradiction with the magnetic field strength BCRSF ~ 4 × 1012 G derived from the observed cyclotron line position may be resolved if the line formation region resides in a tall accretion column of height ~2.5-3 RNS. The color temperature measured from the spectrum suggests that such a column may indeed be present, and our estimates show that its height is sufficient to explain the observed cyclotron line position.

Evidence for a specific influence of the nitrergic pathway on the peripheral pulse waveform in rabbits.

PubMed

Nier, B A; Harrington, L S; Carrier, M J; Weinberg, P D

2008-04-01

The height of the dicrotic notch between the systolic and diastolic peaks of the peripheral pulse wave, expressed as a fraction of the overall amplitude of the wave, is sensitive to nitric oxide (NO) bioactivity. This phenomenon might form the basis of a simple, non-invasive method for determining endothelial function in vivo. We assessed whether the phenomenon is specific to the NO pathway or whether other vasoactive agents have similar effects. The relative height of the dicrotic notch (RHDN) was determined by photoplethysmography in the rabbit ear. It was dose-dependently decreased by acetylcholine, a stimulator of endothelial NO synthesis, and increased by N(G)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO synthesis. There was no effect on RHDN of the alpha-adrenergic blocker phentolamine or the beta-adrenergic blocker propranolol. The cyclo-oxygenase inhibitor indomethacin dose-dependently decreased RHDN but this effect was blocked by L-NAME, suggesting it was mediated by cross-talk with the NO pathway. Changes in RHDN appeared to be independent of heart rate and of the delay between the systolic peak and the notch, but were associated with changes in the slope of the dicrotic limb. Both L-NAME and phentolamine produced multiple diastolic peaks, indicative of wave reflections in the vasculature. These data support the view that changes in RHDN are specific to the NO pathway and provide additional information about the mechanisms involved.

The pulse-mass index as a predictor of cardiovascular events in women with systemic lupus erythematosus.

PubMed

García-Villegas, Elsy Aidé; Márquez-González, Horacio; Flores-Suárez, Luis Felipe; Villa-Romero, Antonio Rafael

2017-01-20

Patients with systemic lupus erythematosus (SLE) have 3times the risk of death compared to the rest of the population, with cardiovascular events (CVD) being one of the main causes. Índices such as waist-height (W-Ht I), waist-hip (W-Hp I) and pulse-mass (PMI) predict CVD, though the behaviour is unknown in patients with SLE. The aim of this study was to determine the prognostic value of PMI in the development of CVD in premenopausal women with SLE. Cohort study. Included were premenopausal women with SLE without prior CVD; excluded were those patients with antiphospholipid syndrome (APS), pregnancy, thyroid disease, recent liposuction, and chronic kidney disease. Exposure variables were: PMI, W-Ht I, W-Hp I and metabolic syndrome at onset of the cohort. Considered confounding variables were time of evolution, disease activity, cumulative damage and treatment. Through semi-annual appointments, accident and emergency admittance and hospitalisation records the CVD were screened. Analysis was performed with Cox for proportional hazards and survival with Kaplan Meier. We included 238 women with a median age of 31 (18-52) years, with a follow-up of 8years. We identified 22 (9.6%) cases of CVD. In the Cox proportional hazards analysis, the prognostic variables were: PMI with HR=8.1 (95% CI: 1.1-65), metabolic syndrome with 2.4 (95% CI: 1-5.8), cumulative damage with HR=1.5 (95% CI: 1.1-2.2) and body fat percentage HR=2.8 (95% CI: 1.1-6.9) CONCLUSIONS: The PMI is a better predictor factor of CVD in women with SLE. Copyright © 2016 Elsevier España, S.L.U. All rights reserved.

Central Arterial Function Measured by Non-invasive Pulse Wave Analysis is Abnormal in Patients with Duchenne Muscular Dystrophy.

PubMed

Ryan, Thomas D; Parent, John J; Gao, Zhiqian; Khoury, Philip R; Dupont, Elizabeth; Smith, Jennifer N; Wong, Brenda; Urbina, Elaine M; Jefferies, John L

2017-08-01

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder caused by mutation of dystrophin. Cardiovascular involvement includes dilated cardiomyopathy. Non-invasive assessment of vascular function has not been evaluated in DMD. We hypothesize arterial wave reflection is abnormal in patients with DMD. Pulse wave analysis was performed on DMD patients with a SphygmoCor SCOR-PVx System to determine central blood pressure and augmentation index (AIx) as an assessment of arterial wave reflection. Results were compared to a control group. A total of 43 patients with DMD were enrolled, and compared to 43 normal controls. Central systolic blood pressure was lower, while both AIx-75 (7.8 ± 9.6% vs. 2.1 ± 10.4%, p 0.01, DMD vs. normal) and AIx-not corrected (16.8 ± 10.1% vs. -3.6 ± 10.9, p < 0.001, DMD vs. normal) were higher in the DMD compared to control. Using multivariable linear regression model, the variables found to have a significant effect on AIx-not corrected included diagnosis of DMD, height, and heart rate (r 2  = 0.257). The current data suggest that, despite lower central systolic blood pressure, patients with DMD have higher wave reflection when compared to normal controls, which may represent increased arterial stiffness. Overall there appears to be no effect on ventricular systolic function, however the long-term consequence in this group is unknown. Further study is required to determine the mechanism of these differences, which may be related to the effects of systemic steroids or the role of dystrophin in vascular function.

Biomechanical Factors Associated With Jump Height: A Comparison of Cross-Sectional and Pre-to-Posttraining Change Findings.

PubMed

Marshall, Brendan M; Moran, Kieran A

2015-12-01

Previous studies investigating the biomechanical factors associated with maximal countermovement jump height have typically used cross-sectional data. An alternative but less common approach is to use pre-to-posttraining change data, where the relationship between an improvement in jump height and a change in a factor is examined more directly. Our study compared the findings of these approaches. Such an evaluation is necessary because cross-sectional studies are currently a primary source of information for coaches when examining what factors to train to enhance performance. The countermovement jump of 44 males was analyzed before and after an 8-week training intervention. Correlations with jump height were calculated using both cross-sectional (pretraining data only) and pre-to-posttraining change data. Eight factors identified in the cross-sectional analysis were not significantly correlated with a change in jump height in the pre-to-post analysis. Additionally, only 6 of 11 factors identified in the pre-to-post analysis were identified in the cross-sectional analysis. These findings imply that (a) not all factors identified in a cross-sectional analysis may be critical to jump height improvement and (b) cross-sectional analyses alone may not provide an insight into all of the potential factors to train to enhance jump height. Coaches must be aware of these limitations when examining cross-sectional studies to identify factors to train to enhance jump ability. Additional findings highlight that although exercises prescribed to improve jump height should aim to enhance concentric power production at all joints, a particular emphasis on enhancing hip joint peak power may be warranted.

Irradiation of amorphous Ta42Si13N45 film with a femtosecond laser pulse

NASA Astrophysics Data System (ADS)

Romano, V.; Meier, M.; Theodore, N. D.; Marble, D. K.; Nicolet, M.-A.

2011-07-01

Films of 260 nm thickness, with atomic composition Ta42Si13N45, on 4″ silicon wafers, have been irradiated in air with single laser pulses of 200 femtoseconds duration and 800 nm wave length. As sputter-deposited, the films are structurally amorphous. A laterally truncated Gaussian beam with a near-uniform fluence of ˜0.6 J/cm2 incident normally on such a film ablates 23 nm of the film. Cross-sectional transmission electron micrographs show that the surface of the remaining film is smooth and flat on a long-range scale, but contains densely distributed sharp nanoprotrusions that sometimes surpass the height of the original surface. Dark field micrographs of the remaining material show no nanograins. Neither does glancing angle X-ray diffraction with a beam illuminating many diffraction spots. By all evidence, the remaining film remains amorphous after the pulsed femtosecond irradiation. The same single pulse, but with an enhanced and slightly peaked fluence profile, creates a spot with flat peripheral terraces whose lateral extents shrink with depth, as scanning electron and atomic force micrographs revealed. Comparison of the various figures suggests that the sharp nanoprotrusions result from an ejection of material by brittle fraction and spallation, not from ablation by direct beam-solid interaction. Conditions under which spallation should dominate over ablation are discussed.

Impacts of different climate change regimes and extreme climatic events on an alpine meadow community

PubMed Central

Alatalo, Juha M.; Jägerbrand, Annika K.; Molau, Ulf

2016-01-01

Climate variability is expected to increase in future but there exist very few experimental studies that apply different warming regimes on plant communities over several years. We studied an alpine meadow community under three warming regimes over three years. Treatments consisted of (a) a constant level of warming with open-top chambers (ca. 1.9 °C above ambient), (b) yearly stepwise increases in warming (increases of ca. 1.0, 1.9 and 3.5 °C), and (c) pulse warming, a single first-year pulse event of warming (increase of ca. 3.5 °C). Pulse warming and stepwise warming was hypothesised to cause distinct first-year and third-year effects, respectively. We found support for both hypotheses; however, the responses varied among measurement levels (whole community, canopy, bottom layer, and plant functional groups), treatments, and time. Our study revealed complex responses of the alpine plant community to the different experimentally imposed climate warming regimes. Plant cover, height and biomass frequently responded distinctly to the constant level of warming, the stepwise increase in warming and the extreme pulse-warming event. Notably, we found that stepwise warming had an accumulating effect on biomass, the responses to the different warming regimes varied among functional groups, and the short-term perturbations had negative effect on species richness and diversity PMID:26888225

Height and Breast Cancer Risk: Evidence From Prospective Studies and Mendelian Randomization

PubMed Central

Zhang, Ben; Shu, Xiao-Ou; Delahanty, Ryan J.; Zeng, Chenjie; Michailidou, Kyriaki; Bolla, Manjeet K.; Wang, Qin; Dennis, Joe; Wen, Wanqing; Long, Jirong; Li, Chun; Dunning, Alison M.; Chang-Claude, Jenny; Shah, Mitul; Perkins, Barbara J.; Czene, Kamila; Darabi, Hatef; Eriksson, Mikael; Bojesen, Stig E.; Nordestgaard, Børge G.; Nielsen, Sune F.; Flyger, Henrik; Lambrechts, Diether; Neven, Patrick; Wildiers, Hans; Floris, Giuseppe; Schmidt, Marjanka K.; Rookus, Matti A.; van den Hurk, Katja; de Kort, Wim L. A. M.; Couch, Fergus J.; Olson, Janet E.; Hallberg, Emily; Vachon, Celine; Rudolph, Anja; Seibold, Petra; Flesch-Janys, Dieter; Peto, Julian; dos-Santos-Silva, Isabel; Fletcher, Olivia; Johnson, Nichola; Nevanlinna, Heli; Muranen, Taru A.; Aittomäki, Kristiina; Blomqvist, Carl; Li, Jingmei; Humphreys, Keith; Brand, Judith; Guénel, Pascal; Truong, Thérèse; Cordina-Duverger, Emilie; Menegaux, Florence; Burwinkel, Barbara; Marme, Frederik; Yang, Rongxi; Surowy, Harald; Benitez, Javier; Zamora, M. Pilar; Perez, Jose I. A.; Cox, Angela; Cross, Simon S.; Reed, Malcolm W. R.; Andrulis, Irene L.; Knight, Julia A.; Glendon, Gord; Tchatchou, Sandrine; Sawyer, Elinor J.; Tomlinson, Ian; Kerin, Michael J.; Miller, Nicola; Chenevix-Trench, Georgia; Haiman, Christopher A.; Henderson, Brian E.; Schumacher, Fredrick; Marchand, Loic Le; Lindblom, Annika; Margolin, Sara; Hooning, Maartje J.; Martens, John W. M.; Tilanus-Linthorst, Madeleine M. A.; Collée, J. Margriet; Hopper, John L.; Southey, Melissa C.; Tsimiklis, Helen; Apicella, Carmel; Slager, Susan; Toland, Amanda E.; Ambrosone, Christine B.; Yannoukakos, Drakoulis; Giles, Graham G.; Milne, Roger L.; McLean, Catriona; Fasching, Peter A.; Haeberle, Lothar; Ekici, Arif B.; Beckmann, Matthias W.; Brenner, Hermann; Dieffenbach, Aida Karina; Arndt, Volker; Stegmaier, Christa; Swerdlow, Anthony J.; Ashworth, Alan; Orr, Nick; Jones, Michael; Figueroa, Jonine; Garcia-Closas, Montserrat; Brinton, Louise; Lissowska, Jolanta; Dumont, Martine; Winqvist, Robert; Pylkäs, Katri; Jukkola-Vuorinen, Arja; Grip, Mervi; Brauch, Hiltrud; Brüning, Thomas; Ko, Yon-Dschun; Peterlongo, Paolo; Manoukian, Siranoush; Bonanni, Bernardo; Radice, Paolo; Bogdanova, Natalia; Antonenkova, Natalia; Dörk, Thilo; Mannermaa, Arto; Kataja, Vesa; Kosma, Veli-Matti; Hartikainen, Jaana M.; Devilee, Peter; Seynaeve, Caroline; Van Asperen, Christi J.; Jakubowska, Anna; Lubiński, Jan; Jaworska-Bieniek, Katarzyna; Durda, Katarzyna; Hamann, Ute; Torres, Diana; Schmutzler, Rita K.; Neuhausen, Susan L.; Anton-Culver, Hoda; Kristensen, Vessela N.; Grenaker Alnæs, Grethe I.; Pierce, Brandon L.; Kraft, Peter; Peters, Ulrike; Lindstrom, Sara; Seminara, Daniela; Burgess, Stephen; Ahsan, Habibul; Whittemore, Alice S.; John, Esther M.; Gammon, Marilie D.; Malone, Kathleen E.; Tessier, Daniel C.; Vincent, Daniel; Bacot, Francois; Luccarini, Craig; Baynes, Caroline; Ahmed, Shahana; Maranian, Mel; Healey, Catherine S.; González-Neira, Anna; Pita, Guillermo; Alonso, M. Rosario; Álvarez, Nuria; Herrero, Daniel; Pharoah, Paul D. P.; Simard, Jacques; Hall, Per; Hunter, David J.; Easton, Douglas F.

2015-01-01

Background: Epidemiological studies have linked adult height with breast cancer risk in women. However, the magnitude of the association, particularly by subtypes of breast cancer, has not been established. Furthermore, the mechanisms of the association remain unclear. Methods: We performed a meta-analysis to investigate associations between height and breast cancer risk using data from 159 prospective cohorts totaling 5216302 women, including 113178 events. In a consortium with individual-level data from 46325 case patients and 42482 control subjects, we conducted a Mendelian randomization analysis using a genetic score that comprised 168 height-associated variants as an instrument. This association was further evaluated in a second consortium using summary statistics data from 16003 case patients and 41335 control subjects. Results: The pooled relative risk of breast cancer was 1.17 (95% confidence interval [CI] = 1.15 to 1.19) per 10cm increase in height in the meta-analysis of prospective studies. In Mendelian randomization analysis, the odds ratio of breast cancer per 10cm increase in genetically predicted height was 1.22 (95% CI = 1.13 to 1.32) in the first consortium and 1.21 (95% CI = 1.05 to 1.39) in the second consortium. The association was found in both premenopausal and postmenopausal women but restricted to hormone receptor–positive breast cancer. Analyses of height-associated variants identified eight new loci associated with breast cancer risk after adjusting for multiple comparisons, including three loci at 1q21.2, DNAJC27, and CCDC91 at genome-wide significance level P < 5×10–8. Conclusions: Our study provides strong evidence that adult height is a risk factor for breast cancer in women and certain genetic factors and biological pathways affecting adult height have an important role in the etiology of breast cancer. PMID:26296642

Changes in the extreme wave heights over the Baltic Sea

NASA Astrophysics Data System (ADS)

Kudryavtseva, Nadia; Soomere, Tarmo

2017-04-01

Storms over the Baltic Sea and northwestern Europe have a large impact on the population, offshore industry, and shipping. The understanding of extreme events in sea wave heights and their change due to the climate change and variability is critical for assessment of flooding risks and coastal protection. The BACCII Assessment of Climate Change for the Baltic Sea Basin showed that the extreme events analysis of wind waves is currently not very well addressed, as well as satellite observations of the wave heights. Here we discuss the analysis of all existing satellite altimetry data over the Baltic Sea Basin regarding extremes in the wave heights. In this talk for the first time, we present an analysis of 100-yr return periods, fitted generalized Pareto and Weibull distributions, number, and frequency of extreme events in wave heights in the Baltic Sea measured by the multi-mission satellite altimetry. The data span more than 23 years and provide an excellent spatial coverage over the Baltic Sea, allowing to study in details spatial variations and changes in extreme wave heights. The analysis is based on an application of the Initial Distribution Method, Annual Maxima method and Peak-Over-Threshold approach to satellite altimetry data, all validated in comparison with in-situ wave height measurements. Here we show that the 100-yr return periods of wave heights show significant spatial changes over the Baltic Sea indicating a decrease in the southern part of the Baltic Sea and an increase in adjacent areas, which can significantly affect coast vulnerability. Here we compare the observed shift with storm track database data and discuss a spatial correlation and possible connection between the changes in the storm tracks over the Baltic Sea and the change in the extreme wave heights.

Analysis of vertical distributions and effective flight layers of insects: three-dimensional simulation of flying insects and catch at trap heights

USDA-ARS?s Scientific Manuscript database

The mean height and standard deviation (SD) of flight is calculated for over 100 insect species from their catches on trap heights reported in the literature. The iterative equations for calculating mean height and SD are presented. The mean flight height for 95% of the studies varied from 0.17 to 5...

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Science.gov Websites

using mesonet visbility observations and CLARUS QC'd obs; Add ceiling height and sky cover analysis to precipitation coverage gaps near CONUS coastlines; Add significant wave height analysis to OCONUS domains

Echolocation behaviour of the big brown bat (Eptesicus fuscus) in an obstacle avoidance task of increasing difficulty.

PubMed

Sändig, Sonja; Schnitzler, Hans-Ulrich; Denzinger, Annette

2014-08-15

Four big brown bats (Eptesicus fuscus) were challenged in an obstacle avoidance experiment to localize vertically stretched wires requiring progressively greater accuracy by diminishing the wire-to-wire distance from 50 to 10 cm. The performance of the bats decreased with decreasing gap size. The avoidance task became very difficult below a wire separation of 30 cm, which corresponds to the average wingspan of E. fuscus. Two of the bats were able to pass without collisions down to a gap size of 10 cm in some of the flights. The other two bats only managed to master gap sizes down to 20 and 30 cm, respectively. They also performed distinctly worse at all other gap sizes. With increasing difficulty of the task, the bats changed their flight and echolocation behaviour. Especially at gap sizes of 30 cm and below, flight paths increased in height and flight speed was reduced. In addition, the bats emitted approach signals that were arranged in groups. At all gap sizes, the largest numbers of pulses per group were observed in the last group before passing the obstacle. The more difficult the obstacle avoidance task, the more pulses there were in the groups and the shorter the within-group pulse intervals. In comparable situations, the better-performing bats always emitted groups with more pulses than the less well-performing individuals. We hypothesize that the accuracy of target localization increases with the number of pulses per group and that each group is processed as a package. © 2014. Published by The Company of Biologists Ltd.