Analysis of fingerprints features of infrared spectra of various processed products of Radix Aconiti kusnezoffii

NASA Astrophysics Data System (ADS)

Tu-ya; Yang, Ping; Sun, Su-qin; Zhou, Qun; Bao, Xiao-hua; Noda, Isao

2010-06-01

Fourier-transform infrared spectroscopy (FTIR) and two-dimensional correlation infrared spectroscopy (2D-IR)) are employed to analyze various processed products and ether extracts of Radix Aconiti kusnezoffii. There is a resemblance among the spectra of different processed products. The major difference lies in the absorption peak at 1641 cm -1 in the IR spectra, which reflects the transformation of raw aconite to the processed products. There are distinctive differences in the absorption peaks in the range of 1800-1500 cm -1 in the second derivative spectra, which has better resolution, of different processed products. 2D-IR spectra, which elevate the resolution further, can present even more differences among the products in the range of 1800-800 cm -1. Analysis of ether extracts of various processed products proves that there are alcohols, esters, carboxylic acids or ketones in all of them. However, their contents in different samples have obvious differences. With the advantages of high resolution, high-speed and convenience, IR can quickly and precisely distinguish various processed products of Radix A. kusnezoffii, and can be applied to predict the tendency of transformation of the complicated chemical mixture systems under heat perturbation.

VizieR Online Data Catalog: FTS reference UV wavelengths of CrIII (Smillie+, 2008)

NASA Astrophysics Data System (ADS)

Smillie, D. G.; Pickering, J. C.; Smith, P. L.

2009-03-01

The Cr III spectrum was acquired in the wavenumber range 31596 to 63192cm-1, using the Imperial College (IC) VUV FTS, and a PDL as light source. The spectral resolution used, 0.12cm-1, was sufficient to fully resolve the Doppler broadened transition line profiles, for which the average unblended full-width at half maximum (FWHM) was just under 0.3cm-1. (1 data file).

a New Broadband Cavity Enhanced Frequency Comb Spectroscopy Technique Using GHz Vernier Filtering.

NASA Astrophysics Data System (ADS)

Morville, Jérôme; Rutkowski, Lucile; Dobrev, Georgi; Crozet, Patrick

2015-06-01

We present a new approach to Cavity Enhanced - Direct Frequency Comb Spectroscopy where the full emission bandwidth of a Titanium:Sapphire laser is exploited at GHz resolution. The technique is based on a low-resolution Vernier filtering obtained with an appreciable -actively stabilized- mismatch between the cavity Free Spectral Range and the laser repetition rate, using a diffraction grating and a split-photodiode. This particular approach provides an immunity to frequency-amplitude noise conversion, reaching an absorption baseline noise in the 10-9 cm-1 range with a cavity finesse of only 3000. Spectra covering 1800 cm-1 (˜ 55 THz) are acquired in recording times of about 1 second, providing an absorption figure of merit of a few 10-11 cm-1/√{Hz}. Initially tested with ambient air, we report progress in using the Vernier frequency comb method with a discharge source of small radicals. Rutkowski et al, Opt. Lett., 39(23)2014

Expected scientific performance of the three spectrometers on the extreme ultraviolet explorer

NASA Technical Reports Server (NTRS)

Vallerga, J. V.; Jelinsky, P.; Vedder, P. W.; Malina, R. F.

1990-01-01

The expected in-orbit performance of the three spectrometers included on the Extreme Ultraviolet Explorer astronomical satellite is presented. Recent calibrations of the gratings, mirrors and detectors using monochromatic and continuum EUV light sources allow the calculation of the spectral resolution and throughput of the instrument. An effective area range of 0.2 to 2.8 sq cm is achieved over the wavelength range 70-600 A with a peak spectral resolution (FWHM) of 360 assuming a spacecraft pointing knowledge of 10 arc seconds (FWHM). For a 40,000 sec observation, the average 3 sigma sensitivity to a monochromatic line source is 0.003 photons/sq cm s. Simulated observations of known classes of EUV sources, such as hot white dwarfs, and cataclysmic variables are also presented.

Temperature-sensitive gating of hCx26: high-resolution Raman spectroscopy sheds light on conformational changes.

PubMed

Kniggendorf, Ann-Kathrin; Meinhardt-Wollweber, Merve; Yuan, Xiaogang; Roth, Bernhard; Seifert, Astrid; Fertig, Niels; Zeilinger, Carsten

2014-07-01

The temperature-sensitive gating of human Connexin 26 (hCx26) was analyzed with confocal Raman microscopy. High-resolution Raman spectra covering the spectral range between 400 and 1500 rel. cm(-1) with a spectral resolution of 1 cm(-1) were fully annotated, revealing notable differences between the spectrum recorded from solubilized hCx26 in Ca(2+)-buffered POPC at 10°C and any other set of protein conditions (temperature, Ca(2+) presence, POPC presence). Spectral components originating from specific amino acids show that the TM1/EL1 parahelix and probably the TM4 trans-membrane helix and the plug domain are involved in the gating process responsible for fully closing the hemichannel.

VizieR Online Data Catalog: The Fermi-GBM three-year X-ray burst catalog (Jenke+, 2016)

NASA Astrophysics Data System (ADS)

Jenke, P. A.; Linares, M.; Connaughton, V.; Beklen, E.; Camero-Arranz, A.; Finger, M. H.; Wilson-Hodge, C. A.

2018-03-01

Gamma-ray Burst Monitor (GBM) is an all-sky monitor whose primary objective is to extend the energy range over which gamma-ray bursts are observed in the Large Area Telescope on Fermi (Meegan et al. 2009ApJ...702..791M). GBM consists of 12 NaI detectors with a diameter of 12.7 cm and a thickness of 1.27 cm and two bismuth germanate (BGO) detectors with a diameter and thickness of 12.7 cm. GBM has three continuous data types: CTIME data with nominal 0.256 s time resolution and 8-channel spectral resolution used for event detection and localization, CSPEC data with nominal 4.096 s time resolution and 128-channel spectral resolution, which are used for spectral modeling, and CTTE (continuous-time tagged event) data with time stamps (2 μs precision) on individual events at full 128-channel spectral resolution, which were made available in 2012 November. The Fermi-GBM X-ray Burst Monitor relies on daily inspection of CTIME channel 1 (12-25 keV) data and began operations on 2010 March 12. (3 data files).

CIRS High-Resolution Thermal Scans and the Structure of Saturn's B Ring

NASA Astrophysics Data System (ADS)

Brooks, S. M.; Spilker, L. J.; Showalter, M.; Pilorz, S.; Edgington, S. G.

2017-12-01

The flyby of Titan on November 29, 2016, sent the Cassini spacecraft on a trajectory that would take it within 10,000 kilometers of Saturn's F ring multiple times before a subsequent Titan encounter on April 22, 2017, would send it on ballistic trajectory carrying it between Saturn's cloud tops and the planet's D ring for several flybys. This geometry has proven beneficial for high-resolution studies of the rings, not just because of Cassini's proximity to the rings, but also because of the spacecraft's high elevation angle above the rings, which reduces the foreshortening that tends to degrade resolution in the ring plane. We will report on several observations of Saturn's main rings at the high spatial resolutions enabled by the end-of-mission geometry, particulary the B ring, with the Composite Infrared Spectrometer onboard Cassini during the F-ring and proximal orbits. CIRS' three infrared detectors cover a combined spectral range of 10 to 1400 cm-1 (1 mm down to 7 microns). We focus on data from Focal Plane 1, which covers the 10 to 600 cm-1 range (1 mm to 16 microns). The apodized spectral resolution of the instrument can be varied from 15 cm-1 to 0.5 cm-1 (Flasar et al. 2004). FP1's wavelength range makes it well-suited to sensing thermal emission from objects at temperatures typical of Saturn's rings. Correlating ring optical depth with temperatures retrieved from scans of the face of the rings exposed to direct solar illumination (the lit face) and the opposite (unlit) face suggests differences in ring structure or particle transport between the lit and unlit sides of the rings in different regions of the B ring. Lit side temperatures in the core of the B ring range between 82 and 87 K; temperatures on the unlit side of the core vary from 66 K up to 74 K. Ferrari and Reffet (2013) and Pilorz et al. (2015) published thorough analyses of the thermal throughput across this optically thick ring. We will discuss these recent CIRS rings observations and their implications in the context of such work. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2017 California Institute of Technology. Government sponsorship acknowledged.

High-Resolution Fourier Transform Infrared Spectrum of the ν 12 Fundamental Band of Ethylene (C 2H 4)

NASA Astrophysics Data System (ADS)

Tan, T. L.; Lau, S. Y.; Ong, P. P.; Goh, K. L.; Teo, H. H.

2000-10-01

The infrared spectrum of the ν12 fundamental band of ethylene (C2H4) has been measured with an unapodized resolution of 0.004 cm-1 in the frequency range of 1380-1500 cm-1 using the Fourier transform technique. By assigning and fitting a total of 1387 infrared transitions using a Watson's A-reduced Hamiltonian in the Ir representation, rovibrational constants for the upper state (v12 = 1) up to five quartic and three sextic centrifugal distortions terms were derived. They represent the most accurate constants for the band so far. The rms deviation of the fit was 0.00033 cm-1. The A-type ν12 band with a band center at 1442.44299 ± 0.00003 cm-1 was found to be relatively free from local frequency perturbations. The inertial defect Δ12 was found to be 0.24201 ± 0.00002 u Å2.

The High-Resolution Infrared Spectrum of the ν 5Band of Deuterated Formic Acid (DCOOH)

NASA Astrophysics Data System (ADS)

Goh, K. L.; Ong, P. P.; Tan, T. L.; Wang, W. F.; Teo, H. H.

1998-07-01

The Fourier transform infrared spectrum of the ν5band of deuterated formic acid (DCOOH) has been measured with a resolution of 0.004 cm-1in the frequency range of 1090-1180 cm-1. Using a Watson'sA-reduced Hamiltonian in theIrrepresentation, a total of 1731 assigned unperturbed transitions have been analyzed to provide rovibrational constants for the upper state (v5= 1) with a standard deviation of 0.000363 cm-1. The band isAtype with an unperturbed band center at 1142.31075 ± 0.00002 cm-1. The band is expected to be perturbed by a nearby ν4band through a Fermi resonance term and possibly a Coriolis term. The resonance is particularly noticeable forKa= 10, and 11, at highJvalues. About 215 perturbed lines were identified but they were not included in the final fit.

High-resolution Fourier transform infrared spectroscopy and analysis of the ν12 fundamental band of ethylene- d4

NASA Astrophysics Data System (ADS)

Tan, T. L.; Goh, K. L.; Ong, P. P.; Teo, H. H.

1999-12-01

The Fourier transform infrared (IR) spectrum of the ν12 fundamental band of ethylene- d4 (C 2D 4) has been measured with an unapodized resolution of 0.004 cm -1 in the frequency range of 1030-1130 cm -1. A total of 1340 assigned transitions have been analyzed and fitted using a Watson's A-reduced Hamiltonian in the Ir representation to derive rovibrational constants for the upper state ( v12=1) up to five quartic terms with a standard deviation of 0.00042 cm -1. They represent the most accurate constants for the band thus far. The ground state rovibrational constants were also further improved by a fit of combination-differences from the IR measurements. The relatively unperturbed band was found to be basically A-type with a band centre at 1076.98492±0.00003 cm -1.

Towards a microchannel-based X-ray detector with two-dimensional spatial and time resolution and high dynamic range

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

Adams, Bernhard W.; Mane, Anil U.; Elam, Jeffrey W.

X-ray detectors that combine two-dimensional spatial resolution with a high time resolution are needed in numerous applications of synchrotron radiation. Most detectors with this combination of capabilities are based on semiconductor technology and are therefore limited in size. Furthermore, the time resolution is often realised through rapid time-gating of the acquisition, followed by a slower readout. Here, a detector technology is realised based on relatively inexpensive microchannel plates that uses GHz waveform sampling for a millimeter-scale spatial resolution and better than 100 ps time resolution. The technology is capable of continuous streaming of time- and location-tagged events at rates greatermore » than 10 7events per cm 2. Time-gating can be used for improved dynamic range.« less

High-resolution FTIR spectroscopy of the Coriolis interacting nu3 and nu9 fundamentals of methylene fluoride-d2

NASA Astrophysics Data System (ADS)

Goh, K. L.; Tan, T. L.; Ong, P. P.; Chaw, K. H.; Teo, H. H.

The Fourier transform infrared spectrum of the υ3 and υ9 bands of methylene fluoride-d2 (CD2F2) has been recorded with an unapodized resolution of 0.0024cm-1 in the frequency range 970-1080cm-1. These two bands with band centres approximately 26 cm-1 apart were mutually coupled by Coriolis interactions. By fitting a total of 1639 infrared transitions of both υ3 and υ9 with a standard deviation of 0.00084cm-1 S/S using a Watson's A-reduced Hamiltonian in the Ir representation with the inclusion of a first order c-type Coriolis resonance term, two sets of rovibrational constants for υ3 = 1 and υ9 = 1 states were derived. The υ3 band is B-type while the υ9 band is A-type with band centres at 1030.1573 ± 0.0003 and 1003.7435 ± 0.0001cm-1, respectively.

Analysis of the coriolis interaction of the ν12 band with 2 ν10 of cis-d 2-ethylene by high-resolution Fourier transform infrared spectroscopy

NASA Astrophysics Data System (ADS)

Goh, K. L.; Tan, T. L.; Ong, P. P.; Teo, H. H.

2000-08-01

The Fourier transform infrared spectrum of the ν12 band of cis-d 2-ethylene ( cis-C 2H 2D 2) has been recorded with an unapodized resolution of 0.0024 cm -1 in the frequency range of 1280-1400 cm -1. This band was found to be mutually coupled by Coriolis interaction with the unobserved 2 ν10 band situated approximately 10 cm -1 below ν12. By fitting a total of 771 infrared transitions of ν12 with a standard deviation of 0.00075 cm -1 using the Watson's Hamiltonian with the inclusion of a c-type Coriolis resonance term, a set of accurate rovibrational constants for V 12=1 state was derived. The ν12 band is A type with a band centre at 1341.1512±0.0001 cm -1. Accurate rovibrational constants for the V 10=2 state were also derived.

A high-resolution atlas of the infrared spectrum of the Sun and the Earth atmosphere from space: A compilation of ATMOS spectra of the region from 650 to 4800 cm (2.3 to 16 micron). Volume 1: The Sun

NASA Technical Reports Server (NTRS)

Farmer, Crofton B.; Norton, Robert H.

1989-01-01

During the period April 29 through May 2, 1985, the Atmospheric Trace Molecular Spectroscopy experiment was operated as part of the Spacelab-3 payload of the shuttle Challenger. The instrument, a modified Michelson Interferometer covering the frequency range from 600 to 5000/cm, at a spectral resolution of 0.01/cm, recorded infrared spectra of the Sun and of the Earth's atmosphere at times close to entry into and exit from occultation by the Earth's limb as seen from the shuttle orbit of 360 km. Spectra were obtained that are free from absorptions due to constituents of the atmosphere (i.e., solar pure spectra), as well as spectra of the atmosphere itself, covering line-of-sight tangent altitudes that span the range from the lower thermosphere to the bottom of the troposphere. This atlas, believed to be the first record of observations of the continuous high resolution infrared spectrum of the Sun and the Earth's atmosphere from space, provides a compilation of these spectra arranged in a hardcopy format suitable for quick-look reference purposes; the data are also available in digital form.

New High-Resolution Absorption Cross-Section Measurements of HCFC-142B in the Mid-Ir

NASA Astrophysics Data System (ADS)

Le Bris, Karine; Strong, Kimberly; Melo, Stella

2009-06-01

HCFC-142b (1-chloro-1,1-difluoroethane) is a temporary substitute for ozone-depleting chlorofluorocarbons (CFCs). However, due to its high absorption cross-sections in the mid-IR, HCFC-142b is also a highly potent greenhouse gas, now detectable from space by satellite missions. So far, the accuracy of the retrieval has been limited by the lack of reference data in a range of temperatures compatible with atmospheric observations. We present new absorption cross section measurements of HCFC-142b at high-resolution (0.02 cm^{-1}) from 223 K to 283 K in the 600 cm^{-1}- 4000 cm^{-1} spectral window. The composite spectra are calculated for each temperature from a set of acquisitions at different pressures by Fourier transform spectroscopy.

High resolution Fourier transform spectroscopy and crystal-field analysis in Tm,Ho:BaY2F8

NASA Astrophysics Data System (ADS)

Baraldi, A.; Capelletti, R.; Mazzera, M.; Riolo, P.; Amoretti, G.; Magnani, N.; Sani, E.; Toncelli, A.; Tonelli, M.

2005-01-01

A Tm3+- Ho3+ -codoped single crystal of monoclinic BaY2F8 has been characterized by means of high resolution FTIR spectroscopy in the wave number range 2000-24000 cm-1 and in the temperature range 9-300 K. The energy level schemes of the two lanthanide ions as determined by the optical absorption spectra is presented, analyzed, and fitted within a single ion Hamiltonian model. The very small energy separation (about 0.6-1.6 cm-1) measured between the first and second sublevels of the ground state manifolds for both the ions is in line with the theoretical predictions. The impurity-phonon coupling is put into evidence by the thermally induced line shift and broadening, and by the detection of vibronic replicas of a few lines.

Receiver design, performance analysis, and evaluation for space-borne laser altimeters and space-to-space laser ranging systems

NASA Technical Reports Server (NTRS)

Davidson, Frederic M.; Field, Christopher T.; Sun, Xiaoli

1996-01-01

We report here the design and the performance measurements of the breadboard receiver of the Geoscience Laser Altimeter System (GLAS). The measured ranging accuracy was better than 2 cm and 10 cm for 5 ns and 30 ns wide received laser pulses under the expected received signal level, which agreed well with the theoretical analysis. The measured receiver sensitivity or the link margin was also consistent with the theory. The effects of the waveform digitizer sample rate and resolution were also measured.

Demonstration of a rapidly-swept external cavity quantum cascade laser for rapid and sensitive quantification of chemical mixtures

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

Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.

2016-02-13

A rapidly-swept external cavity quantum cascade laser (ECQCL) system for fast open-path quantification of multiple chemicals and mixtures is presented. The ECQCL system is swept over its entire tuning range (>100 cm-1) at frequencies up to 200 Hz. At 200 Hz the wavelength tuning rate and spectral resolution are 2x104 cm-1/sec and < 0.2 cm-1, respectively. The capability of the current system to quantify changes in chemical concentrations on millesecond timescales is demonstrated at atmospheric pressure using an open-path multi-pass cell. The detection limits for chemicals ranged from ppb to ppm levels depending on the absorption cross-section.

Laser-Extinction and High-Resolution Atmospheric Transmission Measurements Conducted at White Sands Missile Range, New Mexico, March 1979.

DTIC Science & Technology

1980-11-19

used is first collimated by auxiliary optics to a diameter of approximately 18 mm. The beam is then focused via the off-axis parabolic mirror shown in...RECEIVER STATIONARY OF AISZERO ~ PAR ABOLA PATH OR PATH - CHOPPER I 90cm 120 cm COLLIMATOR / COLLECTOR XMTR DMOBILE RCvR CAIBAIO C0J POSITION - ETECTOR

TH-CD-201-09: High Spatial Resolution Absorbed Dose to Water Measurements Using Optical Calorimetry in Megavoltage External Beam Therapy

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

Flores-Martinez, E; DeWerd, L; Radtke, J

2016-06-15

Purpose: To develop and implement a high spatial resolution calorimeter methodology to measure absorbed dose to water (ADW) using phase shifts (PSs) of light passing through a water phantom and to compare measurements with theoretical calculations. Methods: Radiation-induced temperature changes were measured using the PSs of a He-Ne laser beam passing through a (10×10×10) cm{sup 3} water phantom. PSs were measured using a Michelson interferometer and recording the time-dependent fringe patterns on a CCD camera. The phantom was positioned at the center of the radiation field. A Varian 21EX was used to deliver 500 MU from a 9 MeV beammore » using a (6×6) cm{sup 2} cone. A 127cm SSD was used and the PSs were measured at depths ranging from of 1.90cm to 2.10cm in steps of 0.05cm by taking profiles at the corresponding rows across the image. PSs were computed by taking the difference between pre- and post-irradiation image frames and then measuring the amplitude of the resulting image profiles. An amplitude-to-PS calibration curve was generated using a piezoelectric transducer to mechanically induce PSs between 0.05 and 1.50 radians in steps of 0.05 radians. The temperature dependence of the refractive index of water at 632.8nm was used to convert PSs to ADW. Measured results were compared with ADW values calculated using the linac output calibration and commissioning data. Results: Milli-radian resolution in PS measurement was achieved using the described methodology. Measured radiation-induced PSs ranged from 0.10 ± 0.01 to 0.12 ± 0.01 radians at the investigated depths. After converting PSs to ADW, measured and calculated ADW values agreed within the measurement uncertainty. Conclusion: This work shows that interferometer-based calorimetry measurements are capable of achieving sub-millimeter resolution measuring 2D temperature/dose distributions, which are particularly useful for characterizing beams from modalities such as SRS, proton therapy, or microbeams.« less

A high-resolution atlas of the infrared spectrum of the sun and the earth atmosphere from space. A compilation of ATMOS spectra of the region from 650 to 4800 cm-1 (2.3 to 16 microns). Volume 2: Stratosphere and mesosphere, 650 to 3350 cm-1

NASA Technical Reports Server (NTRS)

Farmer, Crofton B.; Norton, Robert H.

1989-01-01

During the period April 29 to May 2, 1985, the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment was operated for the first time, as part of the Spacelab-3 payload of the shuttle Challenger. The principal purpose of this experiment was to study the distributions of the atmosphere's minor and trace molecular constituents. The instrument, a modified Michelson interferometer covering the frequency range from 600 to 5000/cm-1 at a spectral resolution of 0.01/cm-1, recorded infrared absorption spectra of the sun and of the earth's atmosphere at times close to entry into and exit from occultation by the earth's limb. Spectra were obtained that are free from absorptions due to constituents of the atmosphere (i.e., they are pure solar spectra), as well as spectra of the atmosphere itself, covering line-of-sight tangent altitudes that span the range from the lower thermosphere to the bottom of the troposphere. This atlas presents a compilation of these spectra arranged in a hardcopy format suitable for quick-look reference purposes. Volume 2 covers the stratosphere and mesosphere (i.e., tangent altitudes from 20 to 80 km) for frequencies from 650 to 3350/cm-1.

3D super resolution range-gated imaging for canopy reconstruction and measurement

NASA Astrophysics Data System (ADS)

Huang, Hantao; Wang, Xinwei; Sun, Liang; Lei, Pingshun; Fan, Songtao; Zhou, Yan

2018-01-01

In this paper, we proposed a method of canopy reconstruction and measurement based on 3D super resolution range-gated imaging. In this method, high resolution 2D intensity images are grasped by active gate imaging, and 3D images of canopy are reconstructed by triangular-range-intensity correlation algorithm at the same time. A range-gated laser imaging system(RGLIS) is established based on 808 nm diode laser and gated intensified charge-coupled device (ICCD) camera with 1392´1040 pixels. The proof experiments have been performed for potted plants located 75m away and trees located 165m away. The experiments show it that can acquire more than 1 million points per frame, and 3D imaging has the spatial resolution about 0.3mm at the distance of 75m and the distance accuracy about 10 cm. This research is beneficial for high speed acquisition of canopy structure and non-destructive canopy measurement.

Fourier Transform Infrared (FT-IR) Spectroscopy of Atmospheric Trace Gases HCl, NO and SO2

NASA Technical Reports Server (NTRS)

Haridass, C.; Aw-Musse, A.; Dowdye, E.; Bandyopadhyay, C.; Misra, P.; Okabe, H.

1998-01-01

Fourier Transform Infrared (FT-IR) spectral data have been recorded in the spectral region 400-4000/cm of hydrogen chloride and sulfur dioxide with I/cm resolution and of nitric oxide with 0.25 cm-i resolution, under quasi-static conditions, when the sample gas was passed through tubings of aluminum, copper, stainless steel and teflon. The absorbance was measured for the rotational lines of the fundamental bands of (1)H(35)Cl and (1)H(37)Cl for pressures in the range 100-1000 Torr and for the (14)N(16)O molecule in the range 100-300 Torr. The absorbance was also measured for individual rotational lines corresponding to the three modes of vibrations (upsilon(sub 1) - symmetric stretch, upsilon(sub 2) - symmetric bend, upsilon(sub 3) - anti-symmetric stretch) of the SO2 molecule in the pressure range 25-150 Torr. A graph of absorbance versus pressure was plotted for the observed rotational transitions of the three atmospherically significant molecules, and it was found that the absorbance was linearly proportional to the pressure range chosen, thereby validating Beer's law. The absorption cross-sections were determined from the graphical slopes for each rotational transition recorded for the HCl, NO and SO2 species. Qualitative and quantitative spectral changes in the FT-IR data will be discussed to identify and characterize various tubing materials with respect to their absorption features.

Supporting lander and rover operation: a novel super-resolution restoration technique

NASA Astrophysics Data System (ADS)

Tao, Yu; Muller, Jan-Peter

2015-04-01

Higher resolution imaging data is always desirable to critical rover engineering operations, such as landing site selection, path planning, and optical localisation. For current Mars missions, 25cm HiRISE images have been widely used by the MER & MSL engineering team for rover path planning and location registration/adjustment. However, 25cm is not high enough resolution to be able to view individual rocks (≤2m in size) or visualise the types of sedimentary features that rover onboard cameras might observe. Nevertheless, due to various physical constraints (e.g. telescope size and mass) from the imaging instruments themselves, one needs to be able to tradeoff spatial resolution and bandwidth. This means that future imaging systems are likely to be limited to resolve features larger than 25cm. We have developed a novel super-resolution algorithm/pipeline to be able to restore higher resolution image from the non-redundant sub-pixel information contained in multiple lower resolution raw images [Tao & Muller 2015]. We will demonstrate with experiments performed using 5-10 overlapped 25cm HiRISE images for MER-A, MER-B & MSL to resolve 5-10cm super resolution images that can be directly compared to rover imagery at a range of 5 metres from the rover cameras but in our case can be used to visualise features many kilometres away from the actual rover traverse. We will demonstrate how these super-resolution images together with image understanding software can be used to quantify rock size-frequency distributions as well as measure sedimentary rock layers for several critical sites for comparison with rover orthorectified image mosaic to demonstrate optimality of using our super-resolution resolved image to better support future lander and rover operation in future. We present the potential of super-resolution for virtual exploration to the ˜400 HiRISE areas which have been viewed 5 or more times and the potential application of this technique to all of the ESA ExoMars Trace Gas orbiter CaSSiS stereo, multi-angle and colour camera images from 2017 onwards. Acknowledgements: The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement No.312377 PRoViDE.

High-resolution manometry findings in patients with an intrathoracic stomach.

PubMed

Martinelo, Vanderlei; Mardiros Herbella, Fernando Augusto; Patti, Marco G

2015-04-01

Intrathoracic stomach is a rare finding. The real value of the high-resolution manometry (HRM) in the preoperative evaluation of these patients has not yet being fully tested. This study aims to evaluate: 1) the HRM pattern of patients with an intrathoracic stomach; and 2) HRM findings as predictors for prosthetic reinforcement of the hiatus. We reviewed 33 patients (27 women, mean age 66 years) with an intrathoracic stomach who underwent HRM. Fifteen patients did the HRM as part of preoperative workup and were operated on in our institution. All patients were submitted to a laparoscopic Nissen fundoplication. HRM results show that the lower esophageal sphincter (LES) was transposed in all patients. Hiatal hernia was diagnosed in 21 (63%) patients. The length of the hernia was 4 ± 2 cm (range, 1 to 9 cm). LES oscillation was observed in 23 (69%) patients with a mean of 1 ± 0.4 cm (range, 0.4 to 2 cm). Hiatal mesh reinforcement was necessary in five (33%) of the operated patients. HRM findings did not predict hiatal mesh reinforcement. Our results show that: 1) HRM has a poor sensibility for hiatal hernia diagnosis; 2) half of the patients with an intrathoracic stomach have a normal HRM; and 3) HRM does not predict mesh hiatal hernia repair.

Analysis of the ν 12 Band of Ethylene- 13C 2 by High-Resolution FTIR Spectroscopy

NASA Astrophysics Data System (ADS)

Tan, T. L.; Goh, K. L.; Ong, P. P.; Teo, H. H.

2001-06-01

The Fourier transform infrared (FTIR) spectrum of the ν12 fundamental band of ethylene-13C2 (13C2H4) was recorded with an unapodized resolution of 0.004 cm-1 in the frequency range from 1380 to 1500 cm-1. Rovibrational constants for the upper state (ν12=1) up to five quartic and three sextic centrifugal distortion terms were derived for the first time by assigning and fitting a total of 1177 infrared transitions using a Watson's A-reduced Hamiltonian in the Ir representation. The rms deviation of the fit was 0.00045 cm-1. The ground state rovibrational constants were also determined for the first time by a fit of 738 combination differences from the present infrared measurements, with a rms deviation of 0.00060 cm-1. The A-type ν12 band with a band center at 1436.65411±0.00005 cm-1 was found to be relatively free from local frequency perturbations. The inertial defect Δ12 was found to be 0.24300±0.00002 uÅ2.

Synchrotron Based Fourier Transform Far-Infrared Spectroscopy of CH3NO2

NASA Astrophysics Data System (ADS)

Twagirayezu, Sylvestre; Billinghurst, Brant E.; May, Tim; Dawadi, Mahesh B.; Perry, David S.

2013-06-01

As a slightly asymmetric top molecule (κ = 0.25) with both a free internal rotor and a methyl group, CH_3NO_2 is a benchmark system for studies of torsional motion in a 6-fold potential and of the coupling between a large amplitude vibration and other small-amplitude vibrations. For this purpose, rotationally resolved infrared spectra of CH_3NO_2, have been recorded using the Far-Infrared beamline at the Canadian Light Source, which is equipped with a high resolution Bruker IFS 125HR spectrometer. The observed infrared spectra, in the range 550-1000cm^{-1}, are the average of 300 interferometer scans collected at a nominal resolution of 0.00096cm^{-1}. Two a-type bands, centered at 657.08cm^{-1}for NO symmetric bend and at 917.99cm^{-1}for CN-stretch, have been measured. The initial analysis of a number of torsional states is currently being carried out and the progress will be reported in this talk.

Ray tracing evaluation of a technique for correcting the refraction errors in satellite tracking data

NASA Technical Reports Server (NTRS)

Gardner, C. S.; Rowlett, J. R.; Hendrickson, B. E.

1978-01-01

Errors may be introduced in satellite laser ranging data by atmospheric refractivity. Ray tracing data have indicated that horizontal refractivity gradients may introduce nearly 3-cm rms error when satellites are near 10-degree elevation. A correction formula to compensate for the horizontal gradients has been developed. Its accuracy is evaluated by comparing it to refractivity profiles. It is found that if both spherical and gradient correction formulas are employed in conjunction with meteorological measurements, a range resolution of one cm or less is feasible for satellite elevation angles above 10 degrees.

Synchrotron Based High Resolution Far-Ir Spectroscopy of 1,1-DICHLOROETHYLENE

NASA Astrophysics Data System (ADS)

Peebles, Rebecca A.; Elmuti, Lena F.; Peebles, Sean A.; Obenchain, Daniel A.

2013-06-01

Six vibrational bands of the ^{35}Cl_2C=CH_2 isotopologue of 1,1-dichloroethylene have been recorded in the 350 - 1150 cm^{-1} range using the 0.00096 cm^{-1} resolution far-infrared beamline of the Canadian Light Source synchrotron facility. Results from the analysis of one a-type (ν_9 = 796.01904(8) cm^{-1}, CCl asymmetric stretch) and one c-type (ν_{11} = 868.488626(26) cm^{-1}, CH_2 flap) band will be presented. Over 6000 transitions have now been fitted for these two bands, with ground state rotational and centrifugal distortion constants fixed to values determined by rotational spectroscopy, while the upper state constants have been varied. Anharmonic frequency calculations at the MP2/6-311++G(2d,2p) level were instrumental in assigning the dense spectra. Assignment of additional bands around 603 cm^{-1} (b-type, CCl symmetric stretch, ν_4) and 456 cm^{-1} (c-type, CCl_2 flap, ν_{12}), as well as attempts at assigning the mixed ^{35}Cl^{37}Cl isotopologue spectra for ν_9 and ν_{11}, are in progress. Z. Kisiel, L. Pszczółkowski, Z. Naturforsch, {{50a}, (1995), 347-351.

Evaluating scale and roughness effects in urban flood modelling using terrestrial LIDAR data

NASA Astrophysics Data System (ADS)

Ozdemir, H.; Sampson, C. C.; de Almeida, G. A. M.; Bates, P. D.

2013-10-01

This paper evaluates the results of benchmark testing a new inertial formulation of the St. Venant equations, implemented within the LISFLOOD-FP hydraulic model, using different high resolution terrestrial LiDAR data (10 cm, 50 cm and 1 m) and roughness conditions (distributed and composite) in an urban area. To examine these effects, the model is applied to a hypothetical flooding scenario in Alcester, UK, which experienced surface water flooding during summer 2007. The sensitivities of simulated water depth, extent, arrival time and velocity to grid resolutions and different roughness conditions are analysed. The results indicate that increasing the terrain resolution from 1 m to 10 cm significantly affects modelled water depth, extent, arrival time and velocity. This is because hydraulically relevant small scale topography that is accurately captured by the terrestrial LIDAR system, such as road cambers and street kerbs, is better represented on the higher resolution DEM. It is shown that altering surface friction values within a wide range has only a limited effect and is not sufficient to recover the results of the 10 cm simulation at 1 m resolution. Alternating between a uniform composite surface friction value (n = 0.013) or a variable distributed value based on land use has a greater effect on flow velocities and arrival times than on water depths and inundation extent. We conclude that the use of extra detail inherent in terrestrial laser scanning data compared to airborne sensors will be advantageous for urban flood modelling related to surface water, risk analysis and planning for Sustainable Urban Drainage Systems (SUDS) to attenuate flow.

Evaluating scale and roughness effects in urban flood modelling using terrestrial LIDAR data

NASA Astrophysics Data System (ADS)

Ozdemir, H.; Sampson, C. C.; de Almeida, G. A. M.; Bates, P. D.

2013-05-01

This paper evaluates the results of benchmark testing a new inertial formulation of the de St. Venant equations, implemented within the LISFLOOD-FP hydraulic model, using different high resolution terrestrial LiDAR data (10 cm, 50 cm and 1 m) and roughness conditions (distributed and composite) in an urban area. To examine these effects, the model is applied to a hypothetical flooding scenario in Alcester, UK, which experienced surface water flooding during summer 2007. The sensitivities of simulated water depth, extent, arrival time and velocity to grid resolutions and different roughness conditions are analysed. The results indicate that increasing the terrain resolution from 1 m to 10 cm significantly affects modelled water depth, extent, arrival time and velocity. This is because hydraulically relevant small scale topography that is accurately captured by the terrestrial LIDAR system, such as road cambers and street kerbs, is better represented on the higher resolution DEM. It is shown that altering surface friction values within a wide range has only a limited effect and is not sufficient to recover the results of the 10 cm simulation at 1 m resolution. Alternating between a uniform composite surface friction value (n = 0.013) or a variable distributed value based on land use has a greater effect on flow velocities and arrival times than on water depths and inundation extent. We conclude that the use of extra detail inherent in terrestrial laser scanning data compared to airborne sensors will be advantageous for urban flood modelling related to surface water, risk analysis and planning for Sustainable Urban Drainage Systems (SUDS) to attenuate flow.

Neutron light output response and resolution functions in EJ-309 liquid scintillation detectors

DOE PAGES

Enqvist, Andreas; Lawrence, Christopher C.; Wieger, Brian M.; ...

2013-03-26

Here, the neutron light output response functions and detector resolution functions were measured at Ohio University's tandem Van de Graaff generator for three cylindrical EJ-309 liquid scintillator cells, having dimensions 12.7(circle divide)-by-12.7, 7.6-by-7.6, and 7.6-by-5.1 cm. A 7.44 MeV deuteron beam was used on an Al-27 target generating a continuous spectrum over the energy range from a few hundred keV to over 10 MeV. The light output response functions are determined using an exponential fit. Detector resolution functions are obtained for the 12.7-by-12.7 and 7.6-by-7.6 cm detectors. It is demonstrated that the dependence on detector size is important for themore » light output response functions, but not to the same extent for the resolution function, even when photomultiplier tubes, detector material, and other detector characteristics are carefully matched.« less

Heterodyne spectrophotometry of ozone in the 9.6-micron band using a tunable diode laser

NASA Technical Reports Server (NTRS)

Mcelroy, C. T.; Goldman, A.; Fogal, P. F.; Murcray, D. G.

1990-01-01

Tunable diode laser heterodyne spectrophotometry (TDLHS) has been used to make extremely high resolution (0.0003/cm) solar spectra in the 9.6-micron ozone band. Observations have shown that a signal-to-noise ratio of 120:1 (about 30 percent of theoretical) for an integration time of 1/8 s can be achieved at a resolution of 0.0013 wave numbers. The spectral data have been inverted to yield a total column amount of ozone, in good agreement with that measured at the nearby NOAA ozone monitoring facility in Boulder, Colorado. Line positions for several ozone lines in the spectral region 996-997/cm are reported. Recent improvements have produced a signal-to-noise ratio of 95:1 (about 40 percent of theoretical) at 0.0003/cm and extended the range of wavelengths which can be observed.

Development of a multiplexing fingerprint and high wavenumber Raman spectroscopy technique for real-time in vivo tissue Raman measurements at endoscopy

NASA Astrophysics Data System (ADS)

Bergholt, Mads Sylvest; Zheng, Wei; Huang, Zhiwei

2013-03-01

We report on the development of a novel multiplexing Raman spectroscopy technique using a single laser light together with a volume phase holographic (VPH) grating that simultaneously acquires both fingerprint (FP) and high wavenumber (HW) tissue Raman spectra at endoscopy. We utilize a customized VPH dual-transmission grating, which disperses the incident Raman scattered light vertically onto two separate segments (i.e., -150 to 1950 cm-1 1750 to 3600 cm-1) of a charge-coupled device camera. We demonstrate that the multiplexing Raman technique can acquire high quality in vivo tissue Raman spectra ranging from 800 to 3600 cm-1 within 1.0 s with a spectral resolution of 3 to 6 cm-1 during clinical endoscopy. The rapid multiplexing Raman spectroscopy technique covering both FP and HW ranges developed in this work has potential for improving in vivo tissue diagnosis and characterization at endoscopy.

Performance of Laser Megajoule’s x-ray streak camera

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

Zuber, C., E-mail: celine.zuber@cea.fr; Bazzoli, S.; Brunel, P.

2016-11-15

A prototype of a picosecond x-ray streak camera has been developed and tested by Commissariat à l’Énergie Atomique et aux Énergies Alternatives to provide plasma-diagnostic support for the Laser Megajoule. We report on the measured performance of this streak camera, which almost fulfills the requirements: 50-μm spatial resolution over a 15-mm field in the photocathode plane, 17-ps temporal resolution in a 2-ns timebase, a detection threshold lower than 625 nJ/cm{sup 2} in the 0.05–15 keV spectral range, and a dynamic range greater than 100.

Absorption coefficients of solid NH3 from 50 to 7000 per cm

NASA Technical Reports Server (NTRS)

Sill, G.; Fink, U.; Ferraro, J. R.

1980-01-01

Thin-film spectra of solid NH3 at a resolution of 1 per cm were used to determine its absorption coefficient over the range 50-7000 per cm. The thin films were formed inside a liquid N2 cooled dewar using a variety of substrates and dewar windows. The spectra were recorded with two Fourier spectrometers, one covering the range from 1 to 4 microns and the other from 2.6 to 200 microns. The thickness of the films was measured with a laser interference technique. The absorption coefficients were determined by application of Lambert's law and by a fitting procedure to the observed spectra using thin-film theory. Good agreement was found with the absorption coefficients recently determined by other investigators over a more restricted wavelength range. A metastable phase was observed near a temperature of 90 K and its absorption coefficient is reported. No other major spectral changes with temperature were noted for the range 88-120 K.

Real-time spectroscopic sensing using a widely tunable external cavity-QCL with MOEMS diffraction grating

NASA Astrophysics Data System (ADS)

Ostendorf, Ralf; Butschek, Lorenz; Merten, André; Grahmann, Jan; Jarvis, Jan; Hugger, Stefan; Fuchs, Frank; Wagner, Joachim

2016-02-01

We present spectroscopic measurements performed with an EC-QCL combining a broadly tunable quantum cascade laser chip with a tuning range of more than 300 cm-1 and a resonantly driven MOEMS scanner with an integrated diffraction grating for wavelength selection in Littrow configuration. The grating geometry was optimized to provide high diffraction efficiency over the wide tuning range of the QCL, thus assuring high power density and high spectral resolution in the MIR range. The MOEMS scanner has a resonance frequency of 1 kHz, hence allowing for two full wavelength scans, one up and the other downwards, within 1 ms. The capability for real-time spectroscopic sensing based on MOEMS EC-QCLs is demonstrated by transmission measurements performed on polystyrene reference absorber sheets as well as on gaseous samples of carbon monoxide. For the latter one, a large portion of the characteristic CO absorption band containing several absorption lines in the range of 2070 cm-1 to 2280 cm-1 can be monitored in real-time.

Identification of major backscattering sources in trees and shrubs at 10 GHz

NASA Technical Reports Server (NTRS)

Zoughi, R.; Wu, L. K.; Moore, R. K.

1986-01-01

A short-range very-fine-resolution FM-CW radar scatterometer has been used to identify the primary contributors to 10-GHz radar backscatter from pine, pin oak, American sycamore and sugar maple trees, and from creeping juniper shrubs. This system provided a range resolution of 11 cm and gave a 16-cm diameter illumination area at the target range of about 4 m. For a pine tree, the needles caused the strongest backscatter as well as the strongest attenuation in the radar signal. Cones, although insignificant contributors to the total backscatter, were more important for backscattering than for attenuation. For the rest of the trees, leaves were the strongest cause of backscattering and attenuation. However, in the absence of leaves, the petioles, small twigs, and branches gave relatively strong backscatter. For American sycamore and sugar maple trees, the fruits did not affect the total backscatter unless they were packed in clusters. For creeping juniper the backscattered energy and attenuation in the radar signal were mainly due to the top two layers of the evergreen scales. The contribution of the tree trunks was not determined.

Does Explosive Nuclear Burning Occur in Tidal Disruption Events of White Dwarfs by Intermediate-mass Black Holes?

NASA Astrophysics Data System (ADS)

Tanikawa, Ataru; Sato, Yushi; Nomoto, Ken'ichi; Maeda, Keiichi; Nakasato, Naohito; Hachisu, Izumi

2017-04-01

We investigate nucleosynthesis in tidal disruption events (TDEs) of white dwarfs (WDs) by intermediate-mass black holes. We consider various types of WDs with different masses and compositions by means of three-dimensional (3D) smoothed particle hydrodynamics (SPH) simulations. We model these WDs with different numbers of SPH particles, N, from a few 104 to a few 107 in order to check mass resolution convergence, where SPH simulations with N > 107 (or a space resolution of several 106 cm) have unprecedentedly high resolution in this kind of simulation. We find that nuclear reactions become less active with increasing N and that these nuclear reactions are excited by spurious heating due to low resolution. Moreover, we find no shock wave generation. In order to investigate the reason for the absence of a shock wave, we additionally perform one-dimensional (1D) SPH and mesh-based simulations with a space resolution ranging from 104 to 107 cm, using a characteristic flow structure extracted from the 3D SPH simulations. We find shock waves in these 1D high-resolution simulations, one of which triggers a detonation wave. However, we must be careful of the fact that, if the shock wave emerged in an outer region, it could not trigger the detonation wave due to low density. Note that the 1D initial conditions lack accuracy to precisely determine where a shock wave emerges. We need to perform 3D simulations with ≲106 cm space resolution in order to conclude that WD TDEs become optical transients powered by radioactive nuclei.

Multi-image acquisition-based distance sensor using agile laser spot beam.

PubMed

Riza, Nabeel A; Amin, M Junaid

2014-09-01

We present a novel laser-based distance measurement technique that uses multiple-image-based spatial processing to enable distance measurements. Compared with the first-generation distance sensor using spatial processing, the modified sensor is no longer hindered by the classic Rayleigh axial resolution limit for the propagating laser beam at its minimum beam waist location. The proposed high-resolution distance sensor design uses an electronically controlled variable focus lens (ECVFL) in combination with an optical imaging device, such as a charged-coupled device (CCD), to produce and capture different laser spot size images on a target with these beam spot sizes different from the minimal spot size possible at this target distance. By exploiting the unique relationship of the target located spot sizes with the varying ECVFL focal length for each target distance, the proposed distance sensor can compute the target distance with a distance measurement resolution better than the axial resolution via the Rayleigh resolution criterion. Using a 30 mW 633 nm He-Ne laser coupled with an electromagnetically actuated liquid ECVFL, along with a 20 cm focal length bias lens, and using five spot images captured per target position by a CCD-based Nikon camera, a proof-of-concept proposed distance sensor is successfully implemented in the laboratory over target ranges from 10 to 100 cm with a demonstrated sub-cm axial resolution, which is better than the axial Rayleigh resolution limit at these target distances. Applications for the proposed potentially cost-effective distance sensor are diverse and include industrial inspection and measurement and 3D object shape mapping and imaging.

High-resolution vibrational spectroscopy of Pb-OH defects in KMgF3 fluoroperovskite single crystals

NASA Astrophysics Data System (ADS)

Baraldi, A.; Bertoli, P.; Capelletti, R.; Ruffini, A.; Scacco, A.

2001-04-01

High-resolution (0.04 cm-1) Fourier transform infrared spectroscopy in the temperature range 9-300 K is applied to detect and analyze the OH- stretching modes in air grown KMgF3 single crystals, doped with different Pb amounts. In addition to the 3733.7 cm-1 line attributed to the stretching mode of isolated OH-, two main lines peaking at 3550.9 and 3567.7 cm-1 are due to the OH- stretching modes perturbed by neighboring Pb defects. Suitable thermal treatments and isotopic substitutions provide models of the complexes in which OH and Pb are embedded. Lead is recognized as favoring the OH- inclusion into the lattice and causing an inhomogeneous broadening of the IR lines related to the stretching modes of OH- interacting with other cation impurities. Anharmonicity effects are monitored by the weak overtones of the OH-related lines and discussed in the framework of the Morse model for the anharmonic oscillator. The anharmonicity and the Morse parameters, which show a very weak temperature dependence in the 9-300 K range, are very close to those displayed by alkali fluorides. The temperature dependence of the line position and linewidth of the narrow (0.4-0.9 cm-1) Lorentzian-shaped IR lines and of the related overtones is successfully analyzed by means of the single phonon coupling model. The coupled phonon frequencies, evaluated from the fitting, for the Pb-perturbed OH- stretching modes fall in the frequency range of the highest phonon state density of the host matrix.

Normal-incidence soft X-ray telescopes

NASA Technical Reports Server (NTRS)

Spiller, Eberhard; Mccorkle, R. A.; Wilczynski, J. S.; Golub, Leon; Nystrom, G.; Takacs, P. Z.; Welch, C.

1991-01-01

Photos obtained during 5 min of observation time from the flight of a 25-cm-diameter normal-incidence soft-X-ray (63.5 A) telescope on September 11, 1989, are analyzed, and the data are compared to the results expected from tests of the mirror surfaces. These tests cover a range of spatial periods from 25 cm to 1 A. The photos demonstrate a resolution close to the photon shot-noise limit and a reduction in the scattering of the multilayer mirror compared to a single surface for scattering angles above 1 arcmin, corrresponding to surface irregularities with spatial periods below 10 microns. These results are used to predict the possible performance of future telescopes. Sounding rocket observations might be able to reach a resolution around 0.1 arcsec.

Fiber-optic extrinsic Fabry-Perot interferometer strain sensor with <50 pm displacement resolution using three-wavelength digital phase demodulation.

PubMed

Schmidt, M; Werther, B; Fuerstenau, N; Matthias, M; Melz, T

2001-04-09

A fiber-optic extrinsic Fabry-Perot interferometer strain sensor (EFPI-S) of ls = 2.5 cm sensor length using three-wavelength digital phase demodulation is demonstrated to exhibit <50 pm displacement resolution (<2nm/m strain resolution) when measuring the cross expansion of a PZT-ceramic plate. The sensing (single-mode downlead-) and reflecting fibers are fused into a 150/360 microm capillary fiber where the fusion points define the sensor length. Readout is performed using an improved version of the previously described three-wavelength digital phase demodulation method employing an arctan-phase stepping algorithm. In the resent experiments the strain sensitivity was varied via the mapping of the arctan - lookup table to the 16-Bit DA-converter range from 188.25 k /V (6 Volt range 1130 k ) to 11.7 k /Volt (range 70 k ).

absorption sensor for sensitive temperature and species measurements in high-temperature gases

NASA Astrophysics Data System (ADS)

Spearrin, R. M.; Ren, W.; Jeffries, J. B.; Hanson, R. K.

2014-09-01

A continuous-wave laser absorption diagnostic, based on the infrared CO2 bands near 4.2 and 2.7 μm, was developed for sensitive temperature and concentration measurements in high-temperature gas systems using fixed-wavelength methods. Transitions in the respective R-branches of both the fundamental υ 3 band (~2,350 cm-1) and combination υ 1 + υ 3 band (~3,610 cm-1) were chosen based on absorption line-strength, spectral isolation, and temperature sensitivity. The R(76) line near 2,390.52 cm-1 was selected for sensitive CO2 concentration measurements, and a detection limit of <5 ppm was achieved in shock tube kinetics experiments (~1,300 K). A cross-band, two-line thermometry technique was also established utilizing the R(96) line near 2,395.14 cm-1, paired with the R(28) line near 3,633.08 cm-1. This combination yields high temperature sensitivity (ΔE" = 3,305 cm-1) and expanded range compared with previous intra-band CO2 sensors. Thermometry performance was validated in a shock tube over a range of temperatures (600-1,800 K) important for combustion. Measured temperature accuracy was demonstrated to be better than 1 % over the entire range of conditions, with a standard error of ~0.5 % and µs temporal resolution.

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

James, S St.; Argento, D; Stewart, R

Purpose: The University of Washington Medical Center offers neutron therapy for the palliative and definitive treatment of selected cancers. In vivo field verification has the potential to improve the safe and effective delivery of neutron therapy. We propose a portal imaging method that relies on the creation of positron emitting isotopes (11C and 15O) through (n, 2n) reactions with a PMMA plate placed below the patient. After field delivery, the plate is retrieved from the vault and imaged using a reader that detects annihilation photons. The spatial pattern of activity produced in the PMMA plate provides information to reconstruct themore » neutron fluence map needed to confirm treatment delivery. Methods: We used MCNP to simulate the accumulation of 11C activity in a slab of PMMA 2 mm thick, and GATE was used to simulate the sensitivity and spatial resolution of a prototype imaging system. BGO crystal thicknesses of 1 cm, 2 cm and 3 cm were simulated with detector separations of 2 cm. Crystal pitches of 2 mm and 4 mm were evaluated. Back-projection of the events was used to create a planar image. The spatial resolution was taken to be the FWHM of the reconstructed point source image. Results: The system sensitivity for a point source in the center of the field of view was found to range from 58% for 1 cm thick BGO with 2 mm crystal pitch to 74% for the 3 cm thick BGO crystals with 4 mm crystal pitch. The spatial resolution at the center of the field of view was found to be 1.5 mm for the system with 2 mm crystal pitch and 2.8 mm for the system with the 4 mm crystal pitch. Conclusion: BGO crystals with 4 mm crystal pitch and 3 cm length would offer the best sensitivity reader.« less

High resolution Cerenkov and range detectors for balloon-borne cosmic-ray experiment

NASA Technical Reports Server (NTRS)

Ahlen, S. P.; Cartwright, B. G.; Tarle, G.

1975-01-01

A combination of an active Cerenkov detector and passive range detectors is proposed for the high resolution measurement of isotopic composition in the neighborhood of iron in the galactic cosmic rays. A large area (4,300 sq cm) Cerenkov counter and passive range detectors were tested. Tests with heavy ions (2.1 GeV/amu C-12, 289 MeV/amu Ar-40, and 594 MeV/amu Ne-20) revealed the spatial uniformity of response of the Cerenkov counter to be better than 1% peak-to-peak. Light collection efficiency is independent of projectile energy and incidence angle to within at least 0.5%. Passive Lexan track recorders to measure range in the presence of the nuclear interaction background which results from stopping particles through 0.9 interaction lengths of matter were also tested. It was found that nuclear interactions produce an effective range straggling distribution only approximately 75% wider than that expected from range straggling alone. The combination of these tested techniques makes possible high mass resolution in the neighborhood of iron.

The BATSE experiment on the Gamma Ray Observatory: Solar flare hard x ray and gamma-ray capabilities

NASA Technical Reports Server (NTRS)

Fishman, G. J.; Meegan, C. A.; Wilson, R. B.; Parnell, T. A.; Paciesas, W. S.; Pendleton, G. N.; Hudson, H. S.; Matteson, J. L.; Peterson, L. E.; Cline, T. L.

1989-01-01

The Burst and Transient Source Experiment (BATSE) for the Gamma Ray Observatory (GRO) consists of eight detector modules that provide full-sky coverage for gamma-ray bursts and other transient phenomena such as solar flares. Each detector module has a thin, large-area scintillation detector (2025 sq cm) for high time-resolution studies, and a thicker spectroscopy detector (125 sq cm) to extend the energy range and provide better spectral resolution. The total energy range of the system is 15 keV to 100 MeV. These 16 detectors and the associated onboard data system should provide unprecedented capabilities for observing rapid spectral changes and gamma-ray lines from solar flares. The presence of a solar flare can be detected in real-time by BATSE; a trigger signal is sent to two other experiments on the GRO. The launch of the GRO is scheduled for June 1990, so that BATSE can be an important component of the Max '91 campaign.

High resolution FTIR spectroscopy of BaY2F8 single crystals doped with trivalent Er

NASA Astrophysics Data System (ADS)

Baraldi, A.; Capelletti, R.; Cornelli, M.; Ponzoni, A.; Ruffini, A.; Sperzagni, A.; Tonelli, M.

High resolution (0.04 cm-1) FTIR spectroscopy is applied to monoclinic Er3+-doped BaY2F8 single crystals in the wavenumber range 500-24000 cm-1 and temperature range 9-300 K to study the crystal field splitting of the fundamental 4I15/2 and of the excited 4I13/2, 4I11/2, 4I9/2, 4F9/2, 4S3/2, 2H11/2, 4F7/2, 4F5/2, and 4F3/2 states and the effects caused by increasing Er3+-concentrations (2-20% m.f.), such as inhomogeneous line-broadening and new lines due to Er3+-Er3+ interaction. In the framework of the electron-phonon interaction, the thermally induced line-broadening and -shift are detected and accounted for by the two-phonon Raman model and the vibronic replicas of a few lines are investigated.

Radiometric and geometric characteristics of Pleiades images

NASA Astrophysics Data System (ADS)

Jacobsen, K.; Topan, H.; Cam, A.; Özendi, M.; Oruc, M.

2014-11-01

Pleiades images are distributed with 50 cm ground sampling distance (GSD) even if the physical resolution for nadir images is just 70 cm. By theory this should influence the effective GSD determined by means of point spread function at image edges. Nevertheless by edge enhancement the effective GSD can be improved, but this should cause enlarged image noise. Again image noise can be reduced by image restoration. Finally even optimized image restoration cannot improve the image information from 70 cm to 50 cm without loss of details, requiring a comparison of Pleiades image details with other very high resolution space images. The image noise has been determined by analysis of the whole images for any sub-area with 5 pixels times 5 pixels. Based on the standard deviation of grey values in the small sub-areas the image noise has been determined by frequency analysis. This leads to realistic results, checked by test targets. On the other hand the visual determination of image noise based on apparently homogenous sub-areas results in too high values because the human eye is not able to identify small grey value differences - it is limited to just approximately 40 grey value steps over the available gray value range, so small difference in grey values cannot be seen, enlarging results of a manual noise determination. A tri-stereo combination of Pleiades 1A in a mountainous, but partially urban, area has been analyzed and compared with images of the same area from WorldView-1, QuickBird and IKONOS. The image restoration of the Pleiades images is very good, so the effective image resolution resulted in a factor 1.0, meaning that the effective resolution corresponds to the nominal resolution of 50 cm. This does not correspond to the physical resolution of 70 cm, but by edge enhancement the steepness of the grey value profile across the edge can be enlarged, reducing the width of the point spread function. Without additional filtering edge enhancement enlarges the image noise, but the average image noise of approximately 1.0 grey values related to 8 bit images is very small, not indicating the edge enhancement and the down sampling of the GSD from 70 cm to 50 cm. So the direct comparison with the other images has to give the answer if the image quality of Pleiades images is on similar level as corresponding to the nominal resolution. As expected with the image geometry there is no problem. This is the case for all used space images in the test area, where the point identification limits the accuracy of the scene orientation.

Helium temperature measurements in a hot filament magnetic mirror plasma using high resolution Doppler spectroscopy

NASA Astrophysics Data System (ADS)

Knott, S.; McCarthy, P. J.; Ruth, A. A.

2016-09-01

Langmuir probe and spectroscopic diagnostics are used to routinely measure electron temperature and density over a wide operating range in a reconfigured Double Plasma device at University College Cork, Ireland. The helium plasma, generated through thermionic emission from a negatively biased tungsten filament, is confined by an axisymmetric magnetic mirror configuration using two stacks of NdFeB permanent magnets, each of length 20 cm and diameter 3 cm placed just outside the 15 mm water cooling jacket enclosing a cylindrical vacuum vessel of internal diameter 25 cm. Plasma light is analysed using a Fourier Transform-type Bruker spectrometer with a highest achievable resolution of 0.08 cm-1 . In the present work, the conventional assumption of room temperature ions in the analysis of Langmuir probe data from low temperature plasmas is examined critically using Doppler spectroscopy of the 468.6 nm He II line. Results for ion temperatures obtained from spectroscopic data for a variety of engineering parameters (discharge voltage, gas pressure and plasma current) will be presented.

High-Resolution FTIR Spectrum of the ν 9 Band of Ethylene- D4 (C 2D 4)

NASA Astrophysics Data System (ADS)

Tan, T. L.; Goh, K. L.; Ong, P. P.; Teo, H. H.

2000-08-01

The spectrum of the ν9 fundamental band of ethylene-d4 (C2D4) has been measured with an unapodized resolution of 0.004 cm-1 in the frequency range of 2300-2400 cm-1 using a Fourier transform infrared spectrometer. A total of 549 transitions have been assigned and fitted using a Watson's A-reduced Hamiltonian in the Ir representation to derive rovibrational constants for the upper state (v9 = 1) up to five quartic terms with a standard deviation of 0.00087 cm-1. They represent the most accurate rovibrational constants for the ν9 band so far. About 30 transitions of Ka‧ = 0, one transition of ν9 which were identified to be perturbed possibly by the nearby ν11 and ν2 + ν12 transitions, were not included in the final fit. The ν9 band of C2D4 was found to be basically B-type with an unperturbed band center at 2341.836 94 ± 0.000 13 cm-1.

Cassini infrared Fourier spectroscopic investigation

NASA Astrophysics Data System (ADS)

Kunde, Virgil G.; Ade, Peter A.; Barney, Richard D.; Bergman, D.; Bonnal, Jean-Francois; Borelli, R.; Boyd, D.; Brasunas, John C.; Brown, G.; Calcutt, S. B.; Carroll, F.; Courtin, R.; Cretolle, Jacky; Crooke, Julie A.; Davis, Martin A.; Edberg, S.; Fettig, R.; Flasar, M.; Glenar, David A.; Graham, S.; Hagopian, John G.; Hakun, C. F.; Hayes, Patricia A.; Herath, L.; Horn, Linda; Jennings, Donald E.; Karpati, G.; Kellebenz, C.; Lakew, Brook; Lindsay, J.; Lohr, J.; Lyons, James J.; Martineau, Robert J.; Martino, Anthony J.; Matsumura, M.; McCloskey, J.; Melak, T.; Michel, G.; Morell, Armando; Mosier, C.; Pack, L.; Plants, M.; Robinson, D.; Rodriguez, Louis; Romani, Paul; Schaefer, W. J.; Schmidt, Steve; Trujillo, C.; Vellacott, Tim; Wagner, K.; Yun, D.

1996-10-01

The composite infrared spectrometer (CIRS) is a remote sensing instrument to be flown on the Cassini orbiter. CIRS will retrieve vertical profiles of temperature and gas composition for the atmospheres of Titan and Saturn, from deep in their tropospheres to high in their stratospheres. CIRS will also retrieve information on the thermal properties and composition of Saturn's rings and Saturnian satellites. CIRS consists of a pair of Fourier Transform Spectrometers (FTSs) which together cover the spectral range from 10-1400 cm-1 with a spectral resolution up to 0.5 cm-1. The two interferometers share a 50 cm beryllium Cassegrain telescope. The far-infrared FTS is a polarizing interferometer covering the 10-600 cm-1 range with a pair of thermopile detectors, and a 3.9 mrad field of view. The mid-infrared FTS is a conventional Michelson interferometer covering 200-1400 cm-1 in two spectral bandpasses: 600-1100 cm- 1100-1400 cm(superscript -1 with a 1 by 10 photovoltaic HgCdTe array. Each pixel of the arrays has an approximate 0.3 mrad field of view. The HgCdTe arrays are cooled to approximately 80K with a passive radiative cooler.

Chaotic Brillouin optical correlation-domain analysis

NASA Astrophysics Data System (ADS)

Zhang, Jianzhong; Zhang, Mingtao; Zhang, Mingjiang; Liu, Yi; Feng, Changkun; Wang, Yahui; Wang, Yuncai

2018-04-01

We propose and experimentally demonstrate a chaotic Brillouin optical correlation-domain analysis (BOCDA) system for distributed fiber sensing. The utilization of the chaotic laser with low coherent state ensures high spatial resolution. The experimental results demonstrate a 3.92-cm spatial resolution over a 906-m measurement range. The uncertainty in the measurement of the local Brillouin frequency shift is 1.2MHz. The measurement signal-to-noise ratio is given, which is agreement with the theoretical value.

CALIFA, the Calar Alto Legacy Integral Field Area survey. II. First public data release

NASA Astrophysics Data System (ADS)

Husemann, B.; Jahnke, K.; Sánchez, S. F.; Barrado, D.; Bekeraitė, S.; Bomans, D. J.; Castillo-Morales, A.; Catalán-Torrecilla, C.; Cid Fernandes, R.; Falcón-Barroso, J.; García-Benito, R.; González Delgado, R. M.; Iglesias-Páramo, J.; Johnson, B. D.; Kupko, D.; López-Fernandez, R.; Lyubenova, M.; Marino, R. A.; Mast, D.; Miskolczi, A.; Monreal-Ibero, A.; Gil de Paz, A.; Pérez, E.; Pérez, I.; Rosales-Ortega, F. F.; Ruiz-Lara, T.; Schilling, U.; van de Ven, G.; Walcher, J.; Alves, J.; de Amorim, A. L.; Backsmann, N.; Barrera-Ballesteros, J. K.; Bland-Hawthorn, J.; Cortijo, C.; Dettmar, R.-J.; Demleitner, M.; Díaz, A. I.; Enke, H.; Florido, E.; Flores, H.; Galbany, L.; Gallazzi, A.; García-Lorenzo, B.; Gomes, J. M.; Gruel, N.; Haines, T.; Holmes, L.; Jungwiert, B.; Kalinova, V.; Kehrig, C.; Kennicutt, R. C.; Klar, J.; Lehnert, M. D.; López-Sánchez, Á. R.; de Lorenzo-Cáceres, A.; Mármol-Queraltó, E.; Márquez, I.; Mendez-Abreu, J.; Mollá, M.; del Olmo, A.; Meidt, S. E.; Papaderos, P.; Puschnig, J.; Quirrenbach, A.; Roth, M. M.; Sánchez-Blázquez, P.; Spekkens, K.; Singh, R.; Stanishev, V.; Trager, S. C.; Vilchez, J. M.; Wild, V.; Wisotzki, L.; Zibetti, S.; Ziegler, B.

2013-01-01

We present the first public data release (DR1) of the Calar Alto Legacy Integral Field Area (CALIFA) survey. It consists of science-grade optical datacubes for the first 100 of eventually 600 nearby (0.005 < z < 0.03) galaxies, obtained with the integral-field spectrograph PMAS/PPak mounted on the 3.5 m telescope at the Calar Alto observatory. The galaxies in DR1 already cover a wide range of properties in color-magnitude space, morphological type, stellar mass, and gas ionization conditions. This offers the potential to tackle a variety of open questions in galaxy evolution using spatially resolved spectroscopy. Two different spectral setups are available for each galaxy, (i) a low-resolution V500 setup covering the nominal wavelength range 3745-7500 Å with a spectral resolution of 6.0 Å (FWHM), and (ii) a medium-resolution V1200 setup covering the nominal wavelength range 3650-4840 Å with a spectral resolution of 2.3 Å (FWHM). We present the characteristics and data structure of the CALIFA datasets that should be taken into account for scientific exploitation of the data, in particular the effects of vignetting, bad pixels and spatially correlated noise. The data quality test for all 100 galaxies showed that we reach a median limiting continuum sensitivity of 1.0 × 10-18 erg s-1 cm-2 Å-1 arcsec-2 at 5635 Å and 2.2 × 10-18 erg s-1 cm-2 Å-1 arcsec-2 at 4500 Å for the V500 and V1200 setup respectively, which corresponds to limiting r and g band surface brightnesses of 23.6 mag arcsec-2 and 23.4 mag arcsec-2, or an unresolved emission-line flux detection limit of roughly 1 × 10-17 erg s-1 cm-2 arcsec-2 and 0.6 × 10-17 erg s-1 cm-2 arcsec-2, respectively. The median spatial resolution is 3farcs7, and the absolute spectrophotometric calibration is better than 15% (1σ). We also describe the available interfaces and tools that allow easy access to this first publicCALIFA data at http://califa.caha.es/DR1 Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max- Planck-Institut für Astronomie (MPIA) and the Instituto de Astrofísica de Andalucía (CSIC).

THE HIGH-RESOLUTION INFRARED SPECTRUM OF O$sup 18$-ENRICHED CO$sub 2$

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

Berney, C.V.

1962-01-01

The infrared spectrum of a sample of CO/sub 2/ enriched to about 10 at.% with O/sup 18/ was examined in the region of 5400 to 1620 cm/sup -1/, using an Ebert grating spectrometer with spectral slit widths ranging from 0.4 to 0.2 cm/ sup -1/. Various bands of O/sup 18/-substituted species of CO/sub 2/ were observed, including several which were not previously reported under comparable resolution. These are given, together with the observed band centers in cm/sup - 1/. The data are compared with values calculated from vibrational constants given by Courtoy (Ann. Soc. Sci. Bruxelles 73: No. I, 1959).more » Band centers for the unsymmetrical species were found to be consistently higher than calculated, by 0.2 to 1.3 cm/sup -1/. The anomalously large Fermi resonance constant (52.5 cm/sup -1/) found by Courtoy for C/sup 12/O/sup 16/O/sup 18/ was confirmed, an d the C/sup 12/O/sup 18/ bands observed indicated that it is even higher (around 53.7 cm/sup -1/) for the doubly-substituted species. Rotational data for C/sup 12/O/sup 16/O/sup 18/ indicated that alpha /sup 3/ is abo ut 287 x 10/sup -5/ cm/ sup -1/, slightly smaller than the value suggested by Courtoy. (Dissertation Abstr.)« less

High resolution FTIR spectroscopy of the ν7 band of CD3CCH

NASA Astrophysics Data System (ADS)

Pal, Ayan Kumar; Kshirsagar, R. J.

2018-03-01

The high-resolution Fourier transform spectrum of propyne-d3 (CD3CCH) at room temperature has been recorded in the region of the ν7 band (950-1200 cm-1) at an apodized resolution of 0.004 cm-1. About 2400 lines consisting of a total of 25 sub-bands ranging from KΔK = -13 to 12 have been assigned in the ν7 band of CD3CCH. In the fitting analysis, the ν4 = 1 state to which transitions have not been identified in the experimental spectrum included as a "shadow" state. The data have been analyzed taking into account of the strong x-y Coriolis interaction of the ν7 = 1 state with the ν4 = 1 state. l-type interactions between the ± l components of the ν7 = 1 state, and a weak k-type doubling interaction between ν7 = 1 and ν4 = 1 states have been included in the analysis. The vibration-rotation transitions for K ≥ 8 show fairly large amount of deviation and most likely interacted by other nearby states. The transitions upto K = 7 and Jmax = 61 could be fitted with a standard deviation of 0.0007 cm-1.

Simultaneous measurement of stratospheric O3, H2O, CH4, and N2O profiles from infrared limb thermal emissions

NASA Technical Reports Server (NTRS)

Abbas, M. M.; Glenn, M. J.; Kunde, V. G.; Brasunas, J.; Conrath, B. J.; Maguire, W. C.; Herman, J. R.

1987-01-01

Thermal emission measurements of the earth's stratospheric limb were made with a cryogenically cooled high-resolution Michelson interferometer on a balloon flight launched from Palestine, TX, on Nov. 6, 1984. Infrared spectra for complete limb sequences were obtained over portions of the 700-1940/cm range with an unapodized spectral resolution of 0.03/cm for tangent heights varying from 13 to 39 km. The observed data from 1125 to 1425/cm have been analyzed for simultaneous measurement of O3, H2O, CH4, and N2O profiles. The analysis employs line-by-line and layer-by-layer radiative-transfer calculations, including curvature and refraction effects. The optimum use of geometric and spectral effects is made to obtain sharply peaked weighting functions. Contributions from stratospheric aerosol are included by measuring the light extinction within the window regions of the observed spectra. The retrieved constituent profiles are compared with measurements made with a variety of techniques by other groups. The comparison shows good agreement with the published data for all gases, indicating the capability of retrieving trace gas profiles from high-resolution thermal emission limb measurements.

Does Explosive Nuclear Burning Occur in Tidal Disruption Events of White Dwarfs by Intermediate-mass Black Holes?

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

Tanikawa, Ataru; Sato, Yushi; Hachisu, Izumi

We investigate nucleosynthesis in tidal disruption events (TDEs) of white dwarfs (WDs) by intermediate-mass black holes. We consider various types of WDs with different masses and compositions by means of three-dimensional (3D) smoothed particle hydrodynamics (SPH) simulations. We model these WDs with different numbers of SPH particles, N , from a few 10{sup 4} to a few 10{sup 7} in order to check mass resolution convergence, where SPH simulations with N > 10{sup 7} (or a space resolution of several 10{sup 6} cm) have unprecedentedly high resolution in this kind of simulation. We find that nuclear reactions become less activemore » with increasing N and that these nuclear reactions are excited by spurious heating due to low resolution. Moreover, we find no shock wave generation. In order to investigate the reason for the absence of a shock wave, we additionally perform one-dimensional (1D) SPH and mesh-based simulations with a space resolution ranging from 10{sup 4} to 10{sup 7} cm, using a characteristic flow structure extracted from the 3D SPH simulations. We find shock waves in these 1D high-resolution simulations, one of which triggers a detonation wave. However, we must be careful of the fact that, if the shock wave emerged in an outer region, it could not trigger the detonation wave due to low density. Note that the 1D initial conditions lack accuracy to precisely determine where a shock wave emerges. We need to perform 3D simulations with ≲10{sup 6} cm space resolution in order to conclude that WD TDEs become optical transients powered by radioactive nuclei.« less

Simultaneous detection of 19 K-ras mutations by free-solution conjugate electrophoresis of ligase detection reaction products on glass microchips

PubMed Central

Albrecht, Jennifer Coyne; Kotani, Akira; Lin, Jennifer S.; Soper, Steven A.; Barron, Annelise E.

2015-01-01

We demonstrate here the power and flexibility of free-solution conjugate electrophoresis (FSCE) as a method of separating DNA fragments by electrophoresis with no sieving polymer network. Previous work introduced the coupling of FSCE with ligase detection reaction (LDR) to detect point mutations, even at low abundance compared to the wild-type DNA. Here, four large drag-tags are used to achieve free-solution electrophoretic separation of 19 LDR products ranging in size from 42–66 nt that correspond to mutations in the K-ras oncogene. LDR-FSCE enabled electrophoretic resolution of these 19 LDR-FSCE products by CE in 13.5 minutes (E = 310 V/cm) and by microchip electrophoresis in 140 seconds (E = 350 V/cm). The power of FSCE is demonstrated in the unique characteristic of free-solution separations where the separation resolution is constant no matter the electric field strength. By microchip electrophoresis, the electric field was increased to the maximum of the power supply (E = 700 V/cm), and the 19 LDR-FSCE products were separated in < 70 seconds with almost identical resolution to the separation at E = 350 V/cm. These results will aid the goal of screening K-ras mutations on integrated “sample-in/answer-out” devices with amplification, LDR, and detection all on one platform. PMID:23192597

Accuracy Assessment of Coastal Topography Derived from Uav Images

NASA Astrophysics Data System (ADS)

Long, N.; Millescamps, B.; Pouget, F.; Dumon, A.; Lachaussée, N.; Bertin, X.

2016-06-01

To monitor coastal environments, Unmanned Aerial Vehicle (UAV) is a low-cost and easy to use solution to enable data acquisition with high temporal frequency and spatial resolution. Compared to Light Detection And Ranging (LiDAR) or Terrestrial Laser Scanning (TLS), this solution produces Digital Surface Model (DSM) with a similar accuracy. To evaluate the DSM accuracy on a coastal environment, a campaign was carried out with a flying wing (eBee) combined with a digital camera. Using the Photoscan software and the photogrammetry process (Structure From Motion algorithm), a DSM and an orthomosaic were produced. Compared to GNSS surveys, the DSM accuracy is estimated. Two parameters are tested: the influence of the methodology (number and distribution of Ground Control Points, GCPs) and the influence of spatial image resolution (4.6 cm vs 2 cm). The results show that this solution is able to reproduce the topography of a coastal area with a high vertical accuracy (< 10 cm). The georeferencing of the DSM require a homogeneous distribution and a large number of GCPs. The accuracy is correlated with the number of GCPs (use 19 GCPs instead of 10 allows to reduce the difference of 4 cm); the required accuracy should be dependant of the research problematic. Last, in this particular environment, the presence of very small water surfaces on the sand bank does not allow to improve the accuracy when the spatial resolution of images is decreased.

Fast, High-Resolution Terahertz Radar Imaging at 25 Meters

NASA Technical Reports Server (NTRS)

Cooper, Ken B.; Dengler, Robert J.; Llombart, Nuria; Talukder, Ashit; Panangadan, Anand V.; Peay, Chris S.; Siegel, Peter H.

2010-01-01

We report improvements in the scanning speed and standoff range of an ultra-wide bandwidth terahertz (THz) imaging radar for person-borne concealed object detection. Fast beam scanning of the single-transceiver radar is accomplished by rapidly deflecting a flat, light-weight subreflector in a confocal Gregorian optical geometry. With RF back-end improvements also implemented, the radar imaging rate has increased by a factor of about 30 compared to that achieved previously in a 4 m standoff prototype instrument. In addition, a new 100 cm diameter ellipsoidal aluminum reflector yields beam spot diameters of approximately 1 cm over a 50x50 cm field of view at a range of 25 m, although some aberrations are observed that probably arise from misaligned optics. Through-clothes images of a concealed threat at 25 m range, acquired in 5 seconds, are presented, and the impact of reduced signal-to-noise from an even faster frame rate is analyzed. These results inform the system requirements for eventually achieving sub-second or video-rate THz radar imaging.

Time Course of Symptomatic Recovery After Endoscopic Transsphenoidal Surgery for Pituitary Adenoma Apoplexy in the Modern Era.

PubMed

Zaidi, Hasan A; Cote, David J; Burke, William T; Castlen, Joseph P; Bi, Wenya Linda; Laws, Edward R; Dunn, Ian F

2016-12-01

Pituitary tumor apoplexy can result from either hemorrhagic or infarctive expansion of pituitary adenomas, and the related mass effect can result in compression of critical neurovascular structures. The time course of recovery of visual field deficits, headaches, ophthalmoparesis, and pituitary dysfunction after endoscopic transsphenoidal surgery has not been well established. Medical records were retrospectively reviewed for all patients who underwent endoscopic transsphenoidal surgery for pituitary tumor apoplexy from April 2008 to November 2014. Of 578 patients who underwent transsphenoidal surgery, pituitary tumor apoplexy was identified in 44 patients (7.6%). Two patients had prior surgery, leaving 42 patients for final analysis. These included infarction-related apoplexy in 7 (14.4%) patients, and hemorrhagic apoplexy in 35 (85.6%) patients. Hemorrhagic adenomas had a larger axial tumor diameter than patients with infarctive adenomas (4.4 ± 4.1 cm vs. 1.8 ± 0.8 cm; P < 0.01), but were otherwise equivalent. At an average last follow-up of 2.52 years (range, 0.1-6.7 years), resolution of ophthalmoparesis as a result of pituitary tumor apoplexy demonstrated the longest recovery course (range, 2.4 ± 2.2 months) compared with visual field deficits (range, 8.0 ± 9.9 days), headaches (range, 1.9 ± 3.0 days), or pituitary dysfunction (range, 2.0 ± 1.8 weeks; P < 0.01). All patients who presented with headaches (n = 37) and/or visual disturbances (n = 22) had complete resolution of symptoms at last follow-up, whereas 83.3% of patients who presented with ophthalmoplegia experienced resolution. Endocrinologic dysfunction remained relatively consistent after surgery. Endoscopic transsphenoidal surgery can provide durable resolution of symptoms for patients presenting with pituitary tumor apoplexy. Recovery from headaches, visual, and pituitary dysfunction may be more rapid compared with ophthalmoparesis. Copyright © 2016 Elsevier Inc. All rights reserved.

Approaching bathymetry estimation from high resolution multispectral satellite images using a neuro-fuzzy technique

NASA Astrophysics Data System (ADS)

Corucci, Linda; Masini, Andrea; Cococcioni, Marco

2011-01-01

This paper addresses bathymetry estimation from high resolution multispectral satellite images by proposing an accurate supervised method, based on a neuro-fuzzy approach. The method is applied to two Quickbird images of the same area, acquired in different years and meteorological conditions, and is validated using truth data. Performance is studied in different realistic situations of in situ data availability. The method allows to achieve a mean standard deviation of 36.7 cm for estimated water depths in the range [-18, -1] m. When only data collected along a closed path are used as a training set, a mean STD of 45 cm is obtained. The effect of both meteorological conditions and training set size reduction on the overall performance is also investigated.

Low-altitude remote sensing dataset of DEM and RGB mosaic for AB corridor on July 13 2013 and L2 corridor on July 21 2013

DOE Data Explorer

Baptiste Dafflon

2015-04-07

Low-altitude remote sensing dataset including DEM and RGB mosaic for AB (July 13 2013) and L2 corridor (July 21 2013).Processing flowchart for each corridor:Ground control points (GCP, 20.3 cm square white targets, every 20 m) surveyed with RTK GPS. Acquisition of RGB pictures using a Kite-based platform. Structure from Motion based reconstruction using hundreds of pictures and GCP coordinates. Export of DEM and RGB mosaic in geotiff format (NAD 83, 2012 geoid, UTM zone 4 north) with pixel resolution of about 2 cm, and x,y,z accuracy in centimeter range (less than 10 cm). High-accuracy and high-resolution inside GCPs zone for L2 corridor (500x20m), AB corridor (500x40) DEM will be updated once all GCPs will be measured. Only zones between GCPs are accurate although all the mosaic is provided.

Protein dynamics observed by tunable mid-IR quantum cascade lasers across the time range from 10ns to 1s.

PubMed

Schultz, Bernd-Joachim; Mohrmann, Hendrik; Lorenz-Fonfria, Victor A; Heberle, Joachim

2018-01-05

We have developed a spectrometer based on tunable quantum cascade lasers (QCLs) for recording time-resolved absorption spectra of proteins in the mid-infrared range. We illustrate its performance by recording time-resolved difference spectra of bacteriorhodopsin in the carboxylic range (1800-1700cm -1 ) and on the CO rebinding reaction of myoglobin (1960-1840cm -1 ), at a spectral resolution of 1cm -1 . The spectrometric setup covers the time range from 4ns to nearly a second with a response time of 10-15ns. Absorption changes as low as 1×10 -4 are detected in single-shot experiments at t>1μs, and of 5×10 -6 in kinetics obtained after averaging 100 shots. While previous time-resolved IR experiments have mostly been conducted on hydrated films of proteins, we demonstrate here that the brilliance of tunable quantum cascade lasers is superior to perform ns time-resolved experiments even in aqueous solution (H 2 O). Copyright © 2017 Elsevier B.V. All rights reserved.

Broadband mid-infrared measurements for shock induced chemistry

NASA Astrophysics Data System (ADS)

McGrane, Shawn; Bowlan, Pamela; Brown, Kathryn; Bolme, Cynthia; Cawkwell, Marc

2017-06-01

Vibrational absorption spectroscopy across the mid-infrared range is a ubiquitous diagnostic of chemical effects due to its sensitivity to small variations in bonding. At the high temperatures and pressures relevant to shock induced chemistry, vibrational spectral peaks become very broad, and accessing as much spectral range as possible with high time resolution can significantly aid in deducing chemical dynamics. Here, we report experiments using broadband (<500 cm-1 to >2000 cm-1) mid-infrared femtosecond supercontinua created by four wave mixing in filaments to perform absorption spectroscopy. These broadband mid-infrared supercontinua are detected through upconversion to visible light. Initial efforts to utilize these methods for measurement of chemical dynamics in shocked nitromethane will be reported.

Direct determination of sorbitol and sodium glutamate by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) in the thermostabilizer employed in the production of yellow-fever vaccine.

PubMed

de Castro, Eduardo da S G; Cassella, Ricardo J

2016-05-15

Reference methods for quality control of vaccines usually require treatment of the samples before analysis. These procedures are expensive, time-consuming, unhealthy and require careful manipulation of the sample, making them a potential source of analytical errors. This work proposes a novel method for the quality control of thermostabilizer samples of the yellow fever vaccine employing attenuated total reflectance Fourier transform infrared spectrometry (ATR-FTIR). The main advantage of the proposed method is the possibility of direct determination of the analytes (sodium glutamate and sorbitol) without any pretreatment of the samples. Operational parameters of the FTIR technique, such as the number of accumulated scans and nominal resolution, were evaluated. The best conditions for sodium glutamate were achieved when 64 scans were accumulated using a nominal resolution of 4 cm(-1). The measurements for sodium glutamate were performed at 1347 cm(-1) (baseline correction between 1322 and 1369 cm(-1)). In the case of sorbitol, the measurements were done at 890cm(-1) (baseline correction between 825 and 910 cm(-1)) using a nominal resolution of 2 cm(-1) with 32 accumulated scans. In both cases, the quantitative variable was the band height. Recovery tests were performed in order to evaluate the accuracy of the method and recovery percentages in the range 93-106% were obtained. Also, the methods were compared with reference methods and no statistical differences were observed. The limits of detection and quantification for sodium glutamate were 0.20 and 0.62% (m/v), respectively, whereas for sorbitol they were 1 and 3.3% (m/v), respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

High Resolution Regional Climate Modeling for Lebanon, Eastern Mediterranean Coast

NASA Astrophysics Data System (ADS)

Katurji, Marwan; Soltanzadeh, Iman; Kuhnlein, Meike; Zawar-Reza, Peyman

2013-04-01

The Eastern Mediterranean coast consists of Lebanon, Palestine, Syria, Israel and a small part of southern Turkey. The region lies between latitudes 30 degrees S and 40 degrees N, which makes its climate affected by westerly propagating wintertime cyclones spinning off mid-latitude troughs (December, January and February), while during summer (June, July and August) the area is strongly affected by the sub-tropical anti-cyclonic belt as a result of the descending air of the Hadley cell circulation system. The area is considered to be in a transitional zone between tropical to mid-latitude climate regimes, and having a coastal topography up to 3000 m in elevation (like in the Western Ranges of Lebanon), which emphasizes the complexity of climate variability in this area under future predictions of climate change. This research incorporates both regional climate numerical simulations, Tropical Rainfall Measuring Mission (TRMM) satellite derived and surface rain gauge rainfall data to evaluate the Regional Climate Model (RegCM) version 4 ability to represent both the mean and variance of observed precipitation in the Eastern Mediterranean Region, with emphasis on the Lebanese coastal terrain and mountain ranges. The adopted methodology involves dynamically down scaling climate data from reanalysis synoptic files through a double nesting procedure. The retrospective analysis of 13 years with both 50 and 10 km spatial resolution allows for the assessment of the model results on both a climate scale and specific high intensity precipitating events. The spatial averaged mean bias error in precipitation rate for the rainy season predicted by RegCM 50 and 10 km resolution grids was 0.13 and 0.004 mm hr-1 respectively. When correlating RegCM and TRMM precipitation rate for the domain covering Lebanon's coastal mountains, the root mean square error (RMSE) for the mean quantities over the 13-year period was only 0.03, while the RMSE for the standard deviation was higher by one order of magnitude. Initial results showed good spatial variability agreement for precipitation with the satellite-derived data with improved results for the 10 km grid resolution setup. Also, results show a larger uncertainty within RegCM for predicting extreme precipitation events. Future work will investigate the ability of RegCM to simulate these extreme deviations in precipitation. The results from this research can be helpful for the better design of future regional climate down scaling predictions under climate change scenarios.

Three-dimensional tracking and imaging laser scanner for space operations

NASA Astrophysics Data System (ADS)

Laurin, Denis G.; Beraldin, J. A.; Blais, Francois; Rioux, Marc; Cournoyer, Luc

1999-05-01

This paper presents the development of a laser range scanner (LARS) as a three-dimensional sensor for space applications. The scanner is a versatile system capable of doing surface imaging, target ranging and tracking. It is capable of short range (0.5 m to 20 m) and long range (20 m to 10 km) sensing using triangulation and time-of-flight (TOF) methods respectively. At short range (1 m), the resolution is sub-millimeter and drops gradually with distance (2 cm at 10 m). For long range, the TOF provides a constant resolution of plus or minus 3 cm, independent of range. The LARS could complement the existing Canadian Space Vision System (CSVS) for robotic manipulation. As an active vision system, the LARS is immune to sunlight and adverse lighting; this is a major advantage over the CSVS, as outlined in this paper. The LARS could also replace existing radar systems used for rendezvous and docking. There are clear advantages of an optical system over a microwave radar in terms of size, mass, power and precision. Equipped with two high-speed galvanometers, the laser can be steered to address any point in a 30 degree X 30 degree field of view. The scanning can be continuous (raster scan, Lissajous) or direct (random). This gives the scanner the ability to register high-resolution 3D images of range and intensity (up to 4000 X 4000 pixels) and to perform point target tracking as well as object recognition and geometrical tracking. The imaging capability of the scanner using an eye-safe laser is demonstrated. An efficient fiber laser delivers 60 mW of CW or 3 (mu) J pulses at 20 kHz for TOF operation. Implementation of search and track of multiple targets is also demonstrated. For a single target, refresh rates up to 137 Hz is possible. Considerations for space qualification of the scanner are discussed. Typical space operations, such as docking, object attitude tracking, and inspections are described.

Combined micro-Raman/UV-visible/fluorescence spectrometer for high-throughput analysis of microsamples.

PubMed

Noh, Jermim; Suh, Yung Doug; Park, Yong Ki; Jin, Seung Min; Kim, Soo Ho; Woo, Seong Ihl

2007-07-01

Combined micro-Raman/UV-visible (vis)/fluorescence spectroscopy system, which can evaluate an integrated array of more than 10,000 microsamples with a minimuma size of 5 microm within a few hours, has been developed for the first time. The array of microsamples is positioned on a computer-controlled XY translation microstage with a spatial resolution of 1 mum so that the spectra can be mapped with micron precision. Micro-Raman spectrometers have a high spectral resolution of about 2 cm(-1) over the wave number range of 150-3900 cm(-1), while UV-vis and fluorescence spectrometers have high spectral resolutions of 0.4 and 0.1 nm over the wavelength range of 190-900 nm, respectively. In particular, the signal-to-noise ratio of the micro-Raman spectroscopy has been improved by using a holographic Raman grating and a liquid-nitrogen-cooled charge-coupled device detector. The performance of the combined spectroscopy system has been demonstrated by the high-throughput screening of a combinatorial ferroelectric (i.e., BaTi(x)Zr(1-x)O(3)) library. This system makes possible the structure analysis of various materials including ferroelectrics, catalysts, phosphors, polymers, alloys, and so on for the development of novel materials and the ultrasensitive detection of trace amounts of pharmaceuticals and diagnostic agents.

Fiber fault location utilizing traffic signal in optical network.

PubMed

Zhao, Tong; Wang, Anbang; Wang, Yuncai; Zhang, Mingjiang; Chang, Xiaoming; Xiong, Lijuan; Hao, Yi

2013-10-07

We propose and experimentally demonstrate a method for fault location in optical communication network. This method utilizes the traffic signal transmitted across the network as probe signal, and then locates the fault by correlation technique. Compared with conventional techniques, our method has a simple structure and low operation expenditure, because no additional device is used, such as light source, modulator and signal generator. The correlation detection in this method overcomes the tradeoff between spatial resolution and measurement range in pulse ranging technique. Moreover, signal extraction process can improve the location result considerably. Experimental results show that we achieve a spatial resolution of 8 cm and detection range of over 23 km with -8-dBm mean launched power in optical network based on synchronous digital hierarchy protocols.

Performance of the Fourier transform spectrometer (FTS) for FIS onboard ASTRO-F

NASA Astrophysics Data System (ADS)

Murakami, Noriko; Kawada, Mitsunobu; Takahashi, Hidenori; Ozawa, Keita; Imamura, Tetsuo; Shibai, Hiroshi; Nakagawa, Takao

2004-10-01

We have developed the imaging Fourier Transform Spectrometer (FTS) for the FIS (Far-Infrared Surveyor) onboard the ASTRO-F satellite. A Martin-Puplett interferometer is adopted to achieve high optical efficiency in a wide wavelength range. The total optical efficiency of this spectrometer is achieved 40-80% of the ideal value which is 25% of the incident flux. The wavelength range of 50-200μm is covered with two kinds of detector; the monolithic Ge:Ga photoconductor array for short wavelength (50-110μm) and the stressed Ge:Ga photoconductor array for long wavelength (110-200μm). The spectral resolution expected from the maximum optical path difference is 0.18cm-1. In order to evaluate the spectral resolution of the FTS, we measured absorption lines of H2O in atmosphere using the optics of the FTS with a bolometer at the room temperature. The measured line widths are consistent with the expected instrumental resolution of 0.18 cm-1. Some spectral measurements at the cryogenic temperature were carried out by using cold blackbody sources whose temperatures are controlled in a range from 20 to 50 K. The derived spectra considering with the spectral response of the system are consistent with expected ones. Spectroscopic observations with the FTS will provide a lot of astronomical information; SED of galaxies detected in the all sky survey and the physical diagnostics of the interstellar matter by using the excited atomic or molecular lines.

Airborne 3D Imaging Lidar for Contiguous Decimeter Resolution Terrain Mapping and Shallow Water Bathymetry

NASA Astrophysics Data System (ADS)

Degnan, J. J.; Wells, D. N.; Huet, H.; Chauvet, N.; Lawrence, D. W.; Mitchell, S. E.; Eklund, W. D.

2005-12-01

A 3D imaging lidar system, developed for the University of Florida at Gainesville and operating at the water transmissive wavelength of 532 nm, is designed to contiguously map underlying terrain and/or perform shallow water bathymetry on a single overflight from an altitude of 600 m with a swath width of 225 m and a horizontal spatial resolution of 20 cm. Each 600 psec pulse from a frequency-doubled, low power (~3 microjoules @ 8 kHz = 24 mW), passively Q-switched Nd:YAG microchip laser is passed through a holographic element which projects a 10x10 array of spots onto a 2m x 2m target area. The individual ground spots are then imaged onto individual anodes within a 10x10 segmented anode photomultiplier. The latter is followed by a 100 channel multistop ranging receiver with a range resolution of about 4 cm. The multistop feature permits single photon detection in daylight with wide range gates as well as multiple single photon returns per pixel per laser fire from volumetric scatterers such as tree canopies or turbid water columns. The individual single pulse 3D images are contiguously mosaiced together through the combined action of the platform velocity and a counter-rotating dual wedge optical scanner whose rotations are synchronized to the laser pulse train. The paper provides an overview of the lidar opto-mechanical design, the synchronized dual wedge scanner and servo controller, and the experimental results obtained to date.

High resolution FTIR spectroscopy of fluoroform 12CHF3 and critical analysis of the infrared spectrum from 25 to 1500 cm-1

NASA Astrophysics Data System (ADS)

Albert, S.; Bauerecker, S.; Bekhtereva, E. S.; Bolotova, I. B.; Hollenstein, H.; Quack, M.; Ulenikov, O. N.

2018-05-01

We report high-resolution (? 0.001 cm-1) Fourier Transform Infrared spectra of fluoroform (CHF3) including the pure rotational (far infrared or THz) range (28-65 cm-1), the ν3 fundamental (? = 700.099 cm-1), as well as the associated "hot' band 2ν3 - ν3 (? = 699.295 cm-1) and the 'atmospheric window' range 1100-1250 cm-1 containing the strongly coupled polyad of the levels ν2, ν5 and ν3 + ν6, at room temperature and at 120 K using the collisional cooling cell coupled to our Bruker IFS 125 HR prototype (ZP2001) spectrometer and Bruker IFS 125 HR ETH-SLS prototype at the Swiss Light Source providing intense synchrotron radiation. The pure rotational spectra provide new information about the vibrational ground state of CHF3, which is useful for further analysis of excited vibrational states. The ν3 fundamental band is re-investigated together with the corresponding 'hot' band 2ν3 - ν3 leading to an extension of the existing line lists up to 4430 transitions with ? = 66 for ν3 and 1040 transitions with ? = 43 for 2ν3 - ν3. About 6000 transitions were assigned to rovibrational levels in the polyad ν2/ν5/ν3 + ν6 with ? = 63 for ν2 (? = 1141.457 cm-1), ? = 63 for ν5 (? = 1157.335 cm-1) and ? = 59 for ν3 + ν6 (? = 1208.771 cm-1)(? = ? in each case). The resonance interactions between the ν2, ν5 and ν3 + ν6 states have been taken into account providing an accurate set of effective hamiltonian parameters, which reproduce the experimental results with an accuracy close to the experimental uncertainties (with a root mean square deviation drms = 0.00025 cm-1). The analysis is further extended to the ν4 fundamental (? = 1377.847 cm-1) interacting with 2ν3 (? = 1399.394 cm-1). The results are discussed in relation to the importance of understanding the spectra of CHF3 as a greenhouse gas and as part of our large effort to measure and understand the complete spectrum of CHF3 from the far-infrared to the near-infrared as a prototype for intramolecular quantum dynamics and rovibrational energy redistribution.

High-resolution mapping of the NO2 spatial distribution over Belgian urban areas based on airborne APEX remote sensing

NASA Astrophysics Data System (ADS)

Tack, Frederik; Merlaud, Alexis; Iordache, Marian-Daniel; Danckaert, Thomas; Yu, Huan; Fayt, Caroline; Meuleman, Koen; Deutsch, Felix; Fierens, Frans; Van Roozendael, Michel

2017-05-01

We present retrieval results of tropospheric nitrogen dioxide (NO2) vertical column densities (VCDs), mapped at high spatial resolution over three Belgian cities, based on the DOAS analysis of Airborne Prism EXperiment (APEX) observations. APEX, developed by a Swiss-Belgian consortium on behalf of ESA (European Space Agency), is a pushbroom hyperspectral imager characterised by a high spatial resolution and high spectral performance. APEX data have been acquired under clear-sky conditions over the two largest and most heavily polluted Belgian cities, i.e. Antwerp and Brussels on 15 April and 30 June 2015. Additionally, a number of background sites have been covered for the reference spectra. The APEX instrument was mounted in a Dornier DO-228 aeroplane, operated by Deutsches Zentrum für Luft- und Raumfahrt (DLR). NO2 VCDs were retrieved from spatially aggregated radiance spectra allowing urban plumes to be resolved at the resolution of 60 × 80 m2. The main sources in the Antwerp area appear to be related to the (petro)chemical industry while traffic-related emissions dominate in Brussels. The NO2 levels observed in Antwerp range between 3 and 35 × 1015 molec cm-2, with a mean VCD of 17.4 ± 3.7 × 1015 molec cm-2. In the Brussels area, smaller levels are found, ranging between 1 and 20 × 1015 molec cm-2 and a mean VCD of 7.7 ± 2.1 × 1015 molec cm-2. The overall errors on the retrieved NO2 VCDs are on average 21 and 28 % for the Antwerp and Brussels data sets. Low VCD retrievals are mainly limited by noise (1σ slant error), while high retrievals are mainly limited by systematic errors. Compared to coincident car mobile-DOAS measurements taken in Antwerp and Brussels, both data sets are in good agreement with correlation coefficients around 0.85 and slopes close to unity. APEX retrievals tend to be, on average, 12 and 6 % higher for Antwerp and Brussels, respectively. Results demonstrate that the NO2 distribution in an urban environment, and its fine-scale variability, can be mapped accurately with high spatial resolution and in a relatively short time frame, and the contributing emission sources can be resolved. High-resolution quantitative information about the atmospheric NO2 horizontal variability is currently rare, but can be very valuable for (air quality) studies at the urban scale.

Does resolution of flow field observation influence apparent habitat use and energy expenditure in juvenile coho salmon?

USGS Publications Warehouse

Tullos, Desiree D.; Walter, Cara; Dunham, Jason B.

2016-01-01

This study investigated how the resolution of observation influences interpretation of how fish, juvenile Coho Salmon (Oncorhynchus kisutch), exploit the hydraulic environment in streams. Our objectives were to evaluate how spatial resolution of the flow field observation influenced: (1) the velocities considered to be representative of habitat units; (2) patterns of use of the hydraulic environment by fish; and (3) estimates of energy expenditure. We addressed these objectives using observations within a 1:1 scale physical model of a full-channel log jam in an outdoor experimental stream. Velocities were measured with Acoustic Doppler Velocimetry at a 10 cm grid spacing, whereas fish locations and tailbeat frequencies were documented over time using underwater videogrammetry. Results highlighted that resolution of observation did impact perceived habitat use and energy expenditure, as did the location of measurement within habitat units and the use of averaging to summarize velocities within a habitat unit. In this experiment, the range of velocities and energy expenditure estimates increased with coarsening resolution (grid spacing from 10 to 100 cm), reducing the likelihood of measuring the velocities locally experienced by fish. In addition, the coarser resolutions contributed to fish appearing to select velocities that were higher than what was measured at finer resolutions. These findings indicate the need for careful attention to and communication of resolution of observation in investigating the hydraulic environment and in determining the habitat needs and bioenergetics of aquatic biota.

Determination of phosphate phases in sewage sludge ash-based fertilizers by Raman microspectroscopy.

PubMed

Vogel, Christian; Adam, Christian; McNaughton, Don

2013-09-01

The chemical form of phosphate phases in sewage sludge ash (SSA)-based fertilizers was determined by Raman microspectroscopy. Raman mapping with a lateral resolution of 5 × 5 μm(2) easily detected different compounds present in the fertilizers with the help of recorded reference spectra of pure substances. Quartz and aluminosilicates showed Raman bands in the range of 450-520 cm(-1). Phosphates with apatite structure and magnesium triphosphate were determined at around 960 and 980 cm(-1), respectively. Furthermore, calcium/magnesium pyrophosphates were detected in some samples.

Effects of Molecular Adsorption on the Electronic Structure of Single-Layer Graphene

DTIC Science & Technology

2011-08-03

HgxCd1xTe ( MCT -A) detector at a resolution of 4 cm1. 1000 scans were averaged in about 8 min, and 2-fold zero-filling and triangle apodization were...range was∼10007500 cm1, limited on the low end by the Si transmission and on the high end by the detector response. Note that the spectrometer low-pass...reflections) and without any arbitrary vertical displacement. The dashed line shows the position of δR/R = 0. The increased noise at the high-energy end is

An Overview of the Topography of Mars from the Mars Orbiter Laser Altimeter (MOLA)

NASA Technical Reports Server (NTRS)

Smith, David E.; Zuber, Maria T.

2000-01-01

The Mars Global Surveyor (MGS) spacecraft has now completed more than half of its one-Mars-year mission to globally map Mars. During the MGS elliptical and circular orbit mapping phases, the Mars Orbiter Laser Altimeter (MOLA), an instrument on the MGS payload, has collected over 300 million precise elevation measurements. MOLA measures the range from the MGS spacecraft to the Martian surface and to atmospheric reflections. Range is converted to topography through knowledge of the MGS spacecraft orbit. Ranges from MOLA have resulted in a precise global topographic map of Mars. The instrument has also provided measurements of the width of the backscattered optical pulse and of the 1064 nm reflectivity of the Martian surface and atmosphere. The range resolution of the MOLA instrument is 37.5 cm and the along-track resolution of MOLA ground shots is approx. 300 m; the across-track spacing depends on latitude and time in the mapping orbit. The best current topographic grid has a spatial resolution of approx. 1/16 deg and vertical accuracy of approx. one meter. Additional information is contained in the original extended abstract.

Fourier spectroscopy of the stratospheric emission

NASA Technical Reports Server (NTRS)

Carli, B.; Mencaraglia, F.; Bonetti, A.

1980-01-01

Stratospheric emission spectra in the submillimeter range have been recorded with a resolution of 0.0033/cm with a balloon-borne interferometer. Several minor atmospheric constituents have been identified in a preliminary analysis of the spectra; these are water vapor, oxygen, ozone isotopes, nitric acid, nitrous oxide, hydrofluoric and hydrochloric acids, and carbon monoxide.

Conformational analysis and global warming potentials of 1,1,1,3,3,3-hexafluoro-2-propanol from absorption spectroscopy

NASA Astrophysics Data System (ADS)

Godin, Paul J.; Le Bris, Karine; Strong, Kimberly

2017-12-01

Absorption cross-sections of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) were derived from Fourier transform infrared spectra recorded from 530 to 3400 cm-1 with a resolution of 0.1 cm-1 over a temperature range of 300-362 K. These results were compared to previously published experimental measurements made at room temperature and to a theoretical spectrum from density functional theory (DFT) calculations. Good agreement is found between the experimentally derived results, DFT calculations, and previously published data. The only temperature dependence observed was in the amplitude of some of the absorption peaks due to the changing ratio of the stable conformations of HFIP. This temperature dependence does not result in a significant trend in integrated band strength as a function of temperature. The average value for integrated band strength is found to be (2.649 ± 0.065)x10-16 cm molecule-1 for HFIP over the spectral range of 595 to 3010 cm-1. Radiative efficiency (RE) and the global warming potential (GWP) for HFIP were also derived. A RE of 0.293 ± 0.059 Wm-2ppbv-1 is derived, which leads to a GWP100 of 188 in the range of 530 to 3000 cm-1. The DFT calculation is linearly adjusted to match the experimental spectrum. Using this adjusted DFT spectrum to expand the range below 530 to 0 cm-1 , increases the RE to 0.317 ± 0.063 Wm-2ppbv-1 and the GWP100 to 203.

Measurement of stratospheric trace constituent distributions from balloon-borne far infrared observations

NASA Technical Reports Server (NTRS)

Abbas, M. M.; Guo, J.; Carli, B.; Mencaraglia, F.; Bonetti, A.

1987-01-01

FIR limb thermal emission spectra obtained from balloon-borne measurements made as a part of the Balloon Intercomparison Campaign (BIC) have been analyzed for retrieval of stratospheric trace-constituent distributions. The measurements were made with a high-resolution Michelson interferometer and covered the 15-180/cm spectral range with an unapodized spectral resolution of 0.0033/cm. The retrieved vertical profiles of O3, H2O, HDO, HCN, CO, and isotopes of O3 are presented. The results are compared with the BIC measurements for O3 and H2O made from the same balloon gondola and with other published data. A comparison of the simultaneously retrieved profiles for several gases with the published data shows good agreement and indicates the validity of the FIR data and retrieval techniques and the accuracy of the inferred profiles.

Mobile Laser Scanning along Dieppe coastal cliffs: reliability of the acquired point clouds applied to rockfall assessments

NASA Astrophysics Data System (ADS)

Michoud, Clément; Carrea, Dario; Augereau, Emmanuel; Cancouët, Romain; Costa, Stéphane; Davidson, Robert; Delacourt, Chirstophe; Derron, Marc-Henri; Jaboyedoff, Michel; Letortu, Pauline; Maquaire, Olivier

2013-04-01

Dieppe coastal cliffs, in Normandy, France, are mainly formed by sub-horizontal deposits of chalk and flintstone. Largely destabilized by an intense weathering and the Channel sea erosion, small and large rockfalls are regularly observed and contribute to retrogressive cliff processes. During autumn 2012, cliff and intertidal topographies have been acquired with a Terrestrial Laser Scanner (TLS) and a Mobile Laser Scanner (MLS), coupled with seafloor bathymetries realized with a multibeam echosounder (MBES). MLS is a recent development of laser scanning based on the same theoretical principles of aerial LiDAR, but using smaller, cheaper and portable devices. The MLS system, which is composed by an accurate dynamic positioning and orientation (INS) devices and a long range LiDAR, is mounted on a marine vessel; it is then possible to quickly acquire in motion georeferenced LiDAR point clouds with a resolution of about 15 cm. For example, it takes about 1 h to scan of shoreline of 2 km long. MLS is becoming a promising technique supporting erosion and rockfall assessments along the shores of lakes, fjords or seas. In this study, the MLS system used to acquire cliffs and intertidal areas of the Cap d'Ailly was composed by the INS Applanix POS-MV 320 V4 and the LiDAR Optech Ilirs LR. On the same day, three MLS scans with large overlaps (J1, J21 and J3) have been performed at ranges from 600 m at 4 knots (low tide) up to 200 m at 2.2 knots (up tide) with a calm sea at 2.5 Beaufort (small wavelets). Mean scan resolutions go from 26 cm for far scan (J1) to about 8.1 cm for close scan (J3). Moreover, one TLS point cloud on this test site has been acquired with a mean resolution of about 2.3 cm, using a Riegl LMS Z390i. In order to quantify the reliability of the methodology, comparisons between scans have been realized with the software Polyworks™, calculating shortest distances between points of one cloud and the interpolated surface of the reference point cloud. A MatLab™ routine was also written to extract interesting statistics. First, mean distances between points of the reference point clouds (J21) and its interpolated surface are about 0.35 cm with a standard deviation of 15 cm; errors introduced during the surface interpolation step, especially in vegetated areas, may explain those differences. Then, mean distances between J1's points (resp. J3) and the J21's reference surface are about 4 cm (resp. -17 cm) with a standard deviation of 53 cm (resp. 55 cm). After a best fit alignment of J1 and J3 on J21, mean distances between J1 (resp. J3) and the J21's reference surface decrease to about 0.15 cm (resp. 1.6 cm) with a standard deviation of 41 cm (resp. 21 cm). Finally, mean distances between the TLS point clouds and the J21's reference surface are about 3.2 cm with a standard deviation of 26 cm. In conclusion, MLS devices are able to quickly scan long shoreline with a resolution up to about 10 cm. The precision of the acquired data is relatively small enough to investigate on geomorphological features of coastal cliffs. The ability of the MLS technique to detect and monitor small and large rockfalls will be investigated thanks to new acquisitions of the Dieppe cliffs in a close future and enhanced adapted post-processing steps.

The Cryosphere Model Comparison Tool (CmCt): Ice Sheet Model Validation and Comparison Tool for Greenland and Antarctica

NASA Astrophysics Data System (ADS)

Simon, E.; Nowicki, S.; Neumann, T.; Tyahla, L.; Saba, J. L.; Guerber, J. R.; Bonin, J. A.; DiMarzio, J. P.

2017-12-01

The Cryosphere model Comparison tool (CmCt) is a web based ice sheet model validation tool that is being developed by NASA to facilitate direct comparison between observational data and various ice sheet models. The CmCt allows the user to take advantage of several decades worth of observations from Greenland and Antarctica. Currently, the CmCt can be used to compare ice sheet models provided by the user with remotely sensed satellite data from ICESat (Ice, Cloud, and land Elevation Satellite) laser altimetry, GRACE (Gravity Recovery and Climate Experiment) satellite, and radar altimetry (ERS-1, ERS-2, and Envisat). One or more models can be uploaded through the CmCt website and compared with observational data, or compared to each other or other models. The CmCt calculates statistics on the differences between the model and observations, and other quantitative and qualitative metrics, which can be used to evaluate the different model simulations against the observations. The qualitative metrics consist of a range of visual outputs and the quantitative metrics consist of several whole-ice-sheet scalar values that can be used to assign an overall score to a particular simulation. The comparison results from CmCt are useful in quantifying improvements within a specific model (or within a class of models) as a result of differences in model dynamics (e.g., shallow vs. higher-order dynamics approximations), model physics (e.g., representations of ice sheet rheological or basal processes), or model resolution (mesh resolution and/or changes in the spatial resolution of input datasets). The framework and metrics could also be used for use as a model-to-model intercomparison tool, simply by swapping outputs from another model as the observational datasets. Future versions of the tool will include comparisons with other datasets that are of interest to the modeling community, such as ice velocity, ice thickness, and surface mass balance.

Very high resolution far infrared synchrotron radiation spectrum of methanol-D1 (CH2DOH) in the first three torsional-vibrational modes

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Indra; Billinghurst, B. E.

2016-11-01

In our effort to systematically study the far infrared (FIR) spectra of asymmetrically mono deuterated methanol (CH2DOH) and thereby obtain the transition wavenumbers with better and better accuracy (Mukhopadhyay, 2016a,b), the complete Fourier transform (FT) spectra from FIR to infrared (IR) vibrational bands (in the range 50-1190 cm-1) have been re-recorded using the Synchrotron Radiation Source at the Canadian Light Sources in Saskatchewan, Canada. The resolution of the spectrum is unprecedented, reaching beyond the Doppler limited resolution as low as about 0.0008 cm-1 with a signal to noise (S/N) ratio is many fold better than that can be obtained by commercially available FT spectrometer using thermal sources (e.g., Globar). Spectra were also recorded beyond 1190 cm-1 to about 5000 cm-1 at a somewhat lower resolution of 0.002-0.004 cm-1. In this report the analysis of the b-type and c-type torsional - rotational spectra in the ground vibrational state corresponding to gauche- (e1/o1) to gauche- (e1/o1) and gauche- (e1/o1) to trans- (e0) states in the ground vibrational state are reported and an atlas of the wavenumber for about 2500 FIR assigned absorption lines has been prepared. The transitions within a given sub-band are analyzed using state dependent expansion parameters and the Q-branch origins. The data from previous results (Mukhopadhyay, 2016a,b) along with the present work allowed a global analysis yielding a complete set of molecular parameters. The state dependent molecular parameters reproduce the experimental wavenumbers within experimental uncertainty. In addition, the sensitivity of the spectrum allowed observation of forbidden transitions previously unobserved and helped reassignment of rotational angular momentum quantum numbers of some ΔK = ±1, Q-branch transitions in highly excited states recently reported in the literature. To our knowledge the wavenumbers reported in the present work are the most accurate so far reported in the literature and represent the highest resolution spectra for this molecular species.

Theoretical and experimental study of the electronic states and spectra of KBi and KSb

NASA Astrophysics Data System (ADS)

Setzer, K. D.; Fink, E. H.; Alekseyev, A. B.; Liebermann, H.-P.; Buenker, R. J.

2017-03-01

Gas phase emission spectra of the hitherto unknown free radicals KBi and KSb were measured in the NIR range with a Fourier-transform spectrometer. The emissions were observed from a fast-flow system in which bismuth or antimony vapor in argon carrier gas was passed through a microwave discharge and mixed with potassium vapor in an observation tube. For KBi, two systems of blue-degraded bands observed in the range 5800-7700 cm-1 are assigned to the transitions A3Π (A20+) → X3Σ-(X10+, X21). Nine bands of the A20+ → X10+ and three bands of the A20+ → X21 system were measured at high spectral resolution and rotationally analysed. The rotational and vibrational analyses yielded the spectroscopic parameters of the X10+, X21, and A20+ states. For KSb, in the range of the sensitive Ge detector, only one sequence of bands was measured near 6880 cm-1. By analogy with the previously observed spectra of NaSb and NaAs these bands were identified to be the Δv = 0 sequence of the a2 → X21 transition of KSb. Some very weak bands observed at low resolution in the range 3800-5200 cm-1 are assigned to the transitions A3Π (A21) → X3Σ -(X10+, X21). To aid in the analysis of the experimental data, a series of relativistic configuration interaction calculations has been carried out to obtain potential energy curves for the low-lying states of KBi and KSb, vibrational constants, equilibrium internuclear distances, and also electric dipole transition moments connecting the states.

Resolution Properties of a Calcium Tungstate (CaWO4) Screen Coupled to a CMOS Imaging Detector

NASA Astrophysics Data System (ADS)

Koukou, Vaia; Martini, Niki; Valais, Ioannis; Bakas, Athanasios; Kalyvas, Nektarios; Lavdas, Eleftherios; Fountos, George; Kandarakis, Ioannis; Michail, Christos

2017-11-01

The aim of the current work was to assess the resolution properties of a calcium tungstate (CaWO4) screen (screen coating thickness: 50.09 mg/cm2, actual thickness: 167.2 μm) coupled to a high resolution complementary metal oxide semiconductor (CMOS) digital imaging sensor. A 2.7x3.6 cm2 CaWO4 sample was extracted from an Agfa Curix universal screen and was coupled directly with the active area of the active pixel sensor (APS) CMOS sensor. Experiments were performed following the new IEC 62220-1-1:2015 International Standard, using an RQA-5 beam quality. Resolution was assessed in terms of the Modulation Transfer Function (MTF), using the slanted-edge method. The CaWO4/CMOS detector configuration was found with linear response, in the exposure range under investigation. The final MTF was obtained through averaging the oversampled edge spread function (ESF), using a custom-made software developed by our team, according to the IEC 62220-1-1:2015. Considering the renewed interest in calcium tungstate for various applications, along with the resolution results of this work, CaWO4 could be also considered for use in X-ray imaging devices such as charged-coupled devices (CCD) and CMOS.

Building block extraction and classification by means of aerial images fused with super-resolution reconstructed elevation data

NASA Astrophysics Data System (ADS)

Panagiotopoulou, Antigoni; Bratsolis, Emmanuel; Charou, Eleni; Perantonis, Stavros

2017-10-01

The detailed three-dimensional modeling of buildings utilizing elevation data, such as those provided by light detection and ranging (LiDAR) airborne scanners, is increasingly demanded today. There are certain application requirements and available datasets to which any research effort has to be adapted. Our dataset includes aerial orthophotos, with a spatial resolution 20 cm, and a digital surface model generated from LiDAR, with a spatial resolution 1 m and an elevation resolution 20 cm, from an area of Athens, Greece. The aerial images are fused with LiDAR, and we classify these data with a multilayer feedforward neural network for building block extraction. The innovation of our approach lies in the preprocessing step in which the original LiDAR data are super-resolution (SR) reconstructed by means of a stochastic regularized technique before their fusion with the aerial images takes place. The Lorentzian estimator combined with the bilateral total variation regularization performs the SR reconstruction. We evaluate the performance of our approach against that of fusing unprocessed LiDAR data with aerial images. We present the classified images and the statistical measures confusion matrix, kappa coefficient, and overall accuracy. The results demonstrate that our approach predominates over that of fusing unprocessed LiDAR data with aerial images.

Sci-Fri PM: Radiation Therapy, Planning, Imaging, and Special Techniques - 01: On the use of proton radiography to reduce beam range uncertainties and improve patient positioning accuracy in proton therapy

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

Collins-Fekete, Charles-Antoine; Beaulieu, Luc; Se

2016-08-15

To present two related developments of proton radiography (pRad) to minimize range uncertainty in proton therapy. The first combines a pRad with an X-ray CT to produce a patient-specific relative stopping power (RSP) map. The second aims to improve the pRad spatial resolution for accurate registration prior to the first. The enhanced-pRad can also be used in a novel proton-CT reconstruction algorithm. Monte Carlo pRad were computed from three phantoms; the Gammex, the Catphan and an anthropomorphic head. An optimized cubic-spline estimator derives the most likely path. The length crossed by the protons voxel-by-voxel was calculated by combining their estimatedmore » paths with the CT. The difference between the theoretical (length×RSP) and measured energy loss was minimized through a least squares optimization (LSO) algorithm yielding the RSP map. To increase pRad spatial resolution for registration with the CT, the phantom was discretized into voxels columns. The average column RSP was optimized to maximize the proton energy loss likelihood (MLE). Simulations showed precise RSP (<0.75%) for Gammex materials except low-density lung (<1.2%). For the head, accurate RSP were obtained (µ=−0.10%1.5σ=1.12%) and the range precision was improved (ΔR80 of −0.20±0.35%). Spatial resolution was increased in pRad (2.75 to 6.71 lp/cm) and pCT from MLE-enhanced pRad (2.83 to 5.86 lp/cm). The LSO decreases the range uncertainty (R80σ<1.0%) while the MLE-enhanced pRad spatial resolution (+244%) and is a great candidate for pCT reconstruction.« less

Projection x-space magnetic particle imaging.

PubMed

Goodwill, Patrick W; Konkle, Justin J; Zheng, Bo; Saritas, Emine U; Conolly, Steven M

2012-05-01

Projection magnetic particle imaging (MPI) can improve imaging speed by over 100-fold over traditional 3-D MPI. In this work, we derive the 2-D x-space signal equation, 2-D image equation, and introduce the concept of signal fading and resolution loss for a projection MPI imager. We then describe the design and construction of an x-space projection MPI scanner with a field gradient of 2.35 T/m across a 10 cm magnet free bore. The system has an expected resolution of 3.5 × 8.0 mm using Resovist tracer, and an experimental resolution of 3.8 × 8.4 mm resolution. The system images 2.5 cm × 5.0 cm partial field-of views (FOVs) at 10 frames/s, and acquires a full field-of-view of 10 cm × 5.0 cm in 4 s. We conclude by imaging a resolution phantom, a complex "Cal" phantom, mice injected with Resovist tracer, and experimentally confirm the theoretically predicted x-space spatial resolution.

Photonics-based real-time ultra-high-range-resolution radar with broadband signal generation and processing.

PubMed

Zhang, Fangzheng; Guo, Qingshui; Pan, Shilong

2017-10-23

Real-time and high-resolution target detection is highly desirable in modern radar applications. Electronic techniques have encountered grave difficulties in the development of such radars, which strictly rely on a large instantaneous bandwidth. In this article, a photonics-based real-time high-range-resolution radar is proposed with optical generation and processing of broadband linear frequency modulation (LFM) signals. A broadband LFM signal is generated in the transmitter by photonic frequency quadrupling, and the received echo is de-chirped to a low frequency signal by photonic frequency mixing. The system can operate at a high frequency and a large bandwidth while enabling real-time processing by low-speed analog-to-digital conversion and digital signal processing. A conceptual radar is established. Real-time processing of an 8-GHz LFM signal is achieved with a sampling rate of 500 MSa/s. Accurate distance measurement is implemented with a maximum error of 4 mm within a range of ~3.5 meters. Detection of two targets is demonstrated with a range-resolution as high as 1.875 cm. We believe the proposed radar architecture is a reliable solution to overcome the limitations of current radar on operation bandwidth and processing speed, and it is hopefully to be used in future radars for real-time and high-resolution target detection and imaging.

Fourier transform spectrometers for remote sensing of planetary atmospheres and surfaces

NASA Astrophysics Data System (ADS)

Shakun, Alexey; Korablev, Oleg; Moshkin, Boris; Grigoriev, Alexey; Ignatiev, Nikolay; Maslov, Igor; Sazonov, Oleg; Patsaev, Dmitry; Kungurov, Andrey; Santos-Skripko, Alexander; Zharkov, Alexander; Stupin, Igor; Merzlyakov, Dmitry; Makarov, Vladislav; Martinovich, Fedor; Nikolskiy, Yuri; Shashkin, Victor

2017-12-01

In planetary research, Fourier transform infrared spectrometers (FTIR) solve a number of important scientific goals related both to the atmosphere and to the surface sounding. For remote orbital measurements, these goals are the thermal sounding of the atmosphere using, in particular, the 15-µm CO2 band, sensitive detections of minor gaseous species and aerosol characterization. FTIR can address similar atmospheric science goals when observing from a planetary surface allowing for better-resolved boundary layer and achieving greater accuracy (longer integration) for minor species detection. For studies of planetary surfaces, characterization of mineralogical composition in a wide IR range including sensitive measurements of hydration of the soil on airless bodies can be done. We outline a family of FTIR instruments dedicated to studies of Mars and the Moon. TIRVIM is a channel of ACS on ExoMars TGO (in orbit around Mars since October 2016). It is a 2-inch interferometer for nadir and solar occultation measurements of Mars' atmosphere. It covers a spectral range of 1.7-17 µm with spectral resolution up to 0.13 cm-1. LUMIS is a similar instrument for Luna-Resource Orbiter (Luna-26) Roscosmos mission dedicated to the search for hydration of the lunar regolith in the 6-µm band. The spectral range of LUMIS is broad (1.7-17 µm), but its sensitivity is optimized for the 4-8 µm region. The spectral resolution is 50 cm-1. We also describe recent developments focused on technical solutions for miniaturized FTIR instruments with a very high spectral resolution (0.05 cm-1 and higher). The prototype targets measurements of minor atmospheric species from the surface of Mars using the Sun tracking. One important task is to provide a high precision of interferometer's mirror movement. Another task is the development of a precise two-coordinate mechanism to seek for and follow the Sun.

Implications of MOLA Global Roughness, Statistics, and Topography

NASA Technical Reports Server (NTRS)

Aharonson, O.; Zuber, M. T.; Neumann, G. A.

1999-01-01

New insights are emerging as the ongoing high-quality measurements of the Martian surface topography by Mars Orbiter Laser Altimeter (MOLA) on board the Mars Global Surveyor (MGS) spacecraft increase in coverage, resolution, and diversity. For the first time, a global characterization of the statistical properties of topography is possible. The data were collected during the aerobreaking hiatus, science phasing, and mapping orbits of MGS, and have a resolution of 300-400 m along track, a range resolution of 37.5 cm, a range precision of 1-10 m for surface slopes up to 30 deg., and an absolute accuracy of topography of 13 m. The spacecraft's orbit inclination dictates that nadir observations have latitude coverage of about 87.1S to 87.1N; the addition of observations obtained during a period of off-nadir pointing over the north pole extended coverage to 90N. Additional information is contained in the original extended abstract.

Mid-infrared Study of Stones from the Sutters Mill Meteorite

NASA Technical Reports Server (NTRS)

Nuevo, Michel; Sandford, Scott A.; Flynn, George; Wirick, Sue

2013-01-01

The Sutter's Mill meteorite fell in northern California on April 22, 2012, and numerous pieces have been recovered and studied with several analytical techniques [1]. We present a Fourier-transform infrared (FTIR) spectroscopy analysis of fragments from several stones of the meteorite. Methods and analysis: Infrared spectra of samples SM2 and SM12 were recorded with a Nicolet iN10 MX FTIR microscope in the mid-IR range (4000-650/cm; spectral resolution 4/cm), while samples SM20 and SM30 were analyzed with a synchrotron-based Nicolet Continuum IR microscope in the same range. Samples were deposited on a clean glass slide, crushed with either a stainless steel roller tool or between 2 slides, and placed directly on the focal plane of the microscopes. Results: IR spectra of non-fusion crust samples show several absorption features associated with minerals such as olivines, phyllosilicates, carbonates (calcite and dolomite), and pyroxenes, as well as organics [2]. The carbonates display a main, broad band centered at 1433/cm, with additional bands at 2515/cm, 1797/cm, 882/cm, and 715/cm. Features associated with phyllosilicates include a symmetric Si-O stretching mode band centered at 1011/cm and several O-H stretching mode bands?a broad band centered at 3415/cm that is probably due to adsorbed H2O, and occasionally a much weaker, narrower feature centered near 3680/cm due to structural O-H. Features observed in the 2985-2855/cm range suggest the presence of aliphatic -CH3 and -CH2- groups. However, some of these bands show unusual relative intensities, mainly because of carbonate overtone bands that fall in the same spectral range, which can make the identification of C-H stretching bands problematic. The positions and relative strengths of the aliphatic -CH2- and -CH3 features, where they can be distinguished from overlapping carbonate bands, are consistent with those in interplanetary dust particles (IDPs) and Murchison. Finally, the absence of a strong C=O absorption feature near 1700/cm distinguishes the organics in the Sutter's Mill meteorite from that in most IDPs and in Murchison, but is consistent with the organic matter in Tagish Lake.

Preliminary design of a tangentially viewing imaging bolometer for NSTX-U

DOE PAGES

Peterson, B. J.; Sano, R.; Reinke, M. L.; ...

2016-08-03

The InfraRed imaging Video Bolometer measures plasma radiated power images using a thin metal foil. Two different designs with a tangential view of NSTX-U are made assuming a 640 x 480 (1280 x 1024) pixel, 30 (105) fps, 50 (20) mK, IR camera imaging the 9 cm x 9 cm x 2 μm Pt foil. The foil is divided into 40 x 40 (64 x 64) IRVB channels. This gives a spatial resolution of 3.4 (2.2) cm on the machine mid-plane. The noise equivalent power density of the IRVB is given as 113 (46) μW/cm 2 for a time resolutionmore » of 33 (20) ms. Synthetic images derived from SOLPS data using the IRVB geometry show peak signal levels ranging from ~0.8 - ~80 (~0.36 - ~26) mW/cm 2.« less

Study of radar pulse compression for high resolution satellite altimetry

NASA Technical Reports Server (NTRS)

Dooley, R. P.; Nathanson, F. E.; Brooks, L. W.

1974-01-01

Pulse compression techniques are studied which are applicable to a satellite altimeter having a topographic resolution of + 10 cm. A systematic design procedure is used to determine the system parameters. The performance of an optimum, maximum likelihood processor is analysed, which provides the basis for modifying the standard split-gate tracker to achieve improved performance. Bandwidth considerations lead to the recommendation of a full deramp STRETCH pulse compression technique followed by an analog filter bank to separate range returns. The implementation of the recommended technique is examined.

Atomic torsional modal analysis for high-resolution proteins.

PubMed

Tirion, Monique M; ben-Avraham, Daniel

2015-03-01

We introduce a formulation for normal mode analyses of globular proteins that significantly improves on an earlier one-parameter formulation [M. M. Tirion, Phys. Rev. Lett. 77, 1905 (1996)] that characterized the slow modes associated with protein data bank structures. Here we develop that empirical potential function that is minimized at the outset to include two features essential to reproduce the eigenspectra and associated density of states in the 0 to 300cm-1 frequency range, not merely the slow modes. First, introduction of preferred dihedral-angle configurations via use of torsional stiffness constants eliminates anomalous dispersion characteristics due to insufficiently bound surface side chains and helps fix the spectrum thin tail frequencies (100-300cm-1). Second, we take into account the atomic identities and the distance of separation of all pairwise interactions, improving the spectrum distribution in the 20 to 300cm-1 range. With these modifications, not only does the spectrum reproduce that of full atomic potentials, but we obtain stable reliable eigenmodes for the slow modes and over a wide range of frequencies.

Far Infrared Measurements of Cirrus

NASA Technical Reports Server (NTRS)

Nolt, I. G.; Vanek, M. D.; Tappan, N. D.; Minnis, P.; Alltop, J. L.; Ade, A. R.; Lee, C.; Hamilton, P. A.; Evans, K. F.; Evans, A. H.

1999-01-01

Improved techniques for remote sensing of cirrus are needed to obtain global data for assessing the effect of cirrus in climate change models. Model calculations show that the far infrared/sub-millimeter spectral region is well suited for retrieving cirrus Ice Water Path and particle size parameters. Especially useful cirrus information is obtained at frequencies below 60 cm-1 where single particle scattering dominates over thermal emission for ice particles larger than about 50 m. Earth radiance spectra have been obtained for a range of cloud conditions using an aircraft-based Fourier transform spectrometer. The Far InfraRed Sensor for Cirrus (FIRSC) is a Martin-Puplett interferometer which incorporates a polarizer for the beamsplitter and can be operated in either intensity or linear polarization measurement mode. Two detector channels span 10 to 140 cm-1 with a spectral resolution of 0.1 cm-1; achieving a Noise Equivalent Temperature of approximately 1K at 30 cm-1 in a 4 sec scan. Examples are shown of measured and modeled Earth radiance for a range of cloud conditions from 1998 and 1999 flights.

Impact of the Number of Applied Current Meter Sensors on the Accuracy of Flow Rate Measurements across a Range of Hydroelectric Facilities Indicative of the Domestic Hydroelectric Fleet

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

Christian, Mark H; Hadjerioua, Boualem; Lee, Kyutae

2015-01-01

The following paper represents the results of an investigation into the impact of the number and placement of Current Meter (CM) flow sensors on the accuracy to which they are capable of predicting the overall flow rate. Flow measurement accuracy is of particular importance in multiunit plants because it plays a pivotal role in determining the operational efficiency characteristics of each unit, allowing the operator to select the unit (or combination of units) which most efficiently meet demand. Several case studies have demonstrated that optimization of unit dispatch has the potential to increase plant efficiencies from between 1 to 4.4more » percent [2] [3]. Unfortunately current industry standards do not have an established methodology to measure the flow rate through hydropower units with short converging intakes (SCI); the only direction provided is that CM sensors should be used. The most common application of CM is horizontally, along a trolley which is incrementally lowered across a measurement cross section. As such, the measurement resolution is defined horizontally and vertically by the number of CM and the number of measurement increments respectively. There has not been any published research on the role of resolution in either direction on the accuracy of flow measurement. The work below investigates the effectiveness of flow measurement in a SCI by performing a case study in which point velocity measurements were extracted from a physical plant and then used to calculate a series of reference flow distributions. These distributions were then used to perform sensitivity studies on the relation between the number of CM and the accuracy to which the flow rate was predicted. The following research uncovered that a minimum of 795 plants contain SCI, a quantity which represents roughly 12% of total domestic hydropower capacity. In regards to measurement accuracy, it was determined that accuracy ceases to increase considerably due to strict increases in vertical resolution beyond the application of 49 transects. Moreover the research uncovered that the application of 5 CM (when applied at 49 vertical transects) resulted in an average accuracy of 95.6% and the application of additional sensors resulted in a linear increase in accuracy up to 17 CM which had an average accuracy of 98.5%. Beyond 17 CM incremental increases in accuracy due to the addition of CM was found decrease exponentially. Future work that will be performed in this area will investigate the use of computational fluid dynamics to acquire a broader range of flow fields within SCI.« less

Real-time mid-infrared imaging of living microorganisms.

PubMed

Haase, Katharina; Kröger-Lui, Niels; Pucci, Annemarie; Schönhals, Arthur; Petrich, Wolfgang

2016-01-01

The speed and efficiency of quantum cascade laser-based mid-infrared microspectroscopy are demonstrated using two different model organisms as examples. For the slowly moving Amoeba proteus, a quantum cascade laser is tuned over the wavelength range of 7.6 µm to 8.6 µm (wavenumbers 1320 cm(-1) and 1160 cm(-1) , respectively). The recording of a hyperspectral image takes 11.3 s whereby an average signal-to-noise ratio of 29 is achieved. The limits of time resolution are tested by imaging the fast moving Caenorhabditis elegans at a discrete wavenumber of 1265 cm(-1) . Mid-infrared imaging is performed with the 640 × 480 pixel video graphics array (VGA) standard and at a full-frame time resolution of 0.02 s (i.e. well above the most common frame rate standards). An average signal-to-noise ratio of 16 is obtained. To the best of our knowledge, these findings constitute the first mid-infrared imaging of living organisms at VGA standard and video frame rate. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Airborne Passive Remote Sensing of the Troposphere in Nashville/Middle Tennessee Area During the 1995 Southern Oxidants Study

NASA Technical Reports Server (NTRS)

Rider, D. M.; Worden, H. M.; Beer, R.; Nandi, S.; Sparks, L. C.

1998-01-01

In July of 1995 the Airborne Emission Spectrometer was deployed to Nashville, Tennessee to participate in the 1995 Ozone Study Intensive Campaign of the Southern Oxidants Study. AES is a high resolution mid-infrared interferometer that measures the spectrum of upwelling radiation in the 650-4250 cm-1 range.

Optical spectroscopy of Ce3+ ions in BaY2F8 single crystals

NASA Astrophysics Data System (ADS)

Francini, R.; Pinelli, S.; Baraldi, A.; Capelletti, R.; Sani, E.; Toncelli, A.; Tonelli, M.

In the present work we report on the spectroscopic properties of the Ce3+ ion in BaY2F8 single crystals. The absorption and excitation spectra of the emission centered at 340 nm have been measured in the temperature range 15-300 K. The 340 nm emission consists of two broad partially overlapping bands, peaking at 324 and 347 nm (at 15 K), respectively. The full width at half maximum is about 0.5 eV at room temperature. The absorption spectrum of the lowest in energy component of the f --> d transition of Ce3+ reveals at low temperature a marked vibronic structure. High resolution (0.02 cm(-1)) Fourier transform infrared spectroscopy in the wave number range 500-5000 cm(-1) and in the temperature range 9-300 K has been exploited to monitor the f level splitting. The absorption transitions from the three Stark components of the F-2(5/2) manifold to the four of the F-2(7/2) one, have been monitored in the wave number range 2000-3400 cm(-1) . The wave number separation at 9 K between the lowest level of the ground F-2(5/2) manifold and lowest one of the F-2 (7/2) manifold is found to be 2197.47 cm(-1) in good agreement with the splitting detected between the two components of the d --> f emission.

Shallow water imaging sonar system for environmental surveying. Final report

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

NONE

1998-05-01

The scope of this research is to develop a shallow water sonar system designed to detect and map the location of objects such as hazardous wastes or discarded ordnance in coastal waters. The system will use high frequency wide-bandwidth imaging sonar, mounted on a moving platform towed behind a boat, to detect and identify objects on the sea bottom. Resolved images can be obtained even if the targets are buried in an overlayer of silt. The specific technical objective of this research was to develop and test a prototype system that is capable of (1) scan at high speeds (upmore » to 10m/s), even in shallow water (depth to ten meters), without motion blurring or loss of resolution; (2) produce images of the bottom structure that are detailed enough for unambiguous detection of objects as small as 15cm, even if they are buried up to 30cm deep in silt or sand. The critical technology involved uses an linear FM (LFM) or similar complex waveform, which has a high bandwidth for good range resolution, with a long pulse length for similar Dopper resolution. The lone duration signal deposits more energy on target than a narrower pulse, which increases the signal-to-noise ratio and signal-to-clutter ratio. This in turn allows the use of cheap, lightweight, low power, piezoelectric transducers at the 30--500 kHz range.« less

Use of regional climate model output for hydrologic simulations

USGS Publications Warehouse

Hay, L.E.; Clark, M.P.; Wilby, R.L.; Gutowski, W.J.; Leavesley, G.H.; Pan, Z.; Arritt, R.W.; Takle, E.S.

2002-01-01

Daily precipitation and maximum and minimum temperature time series from a regional climate model (RegCM2) configured using the continental United States as a domain and run on a 52-km (approximately) spatial resolution were used as input to a distributed hydrologic model for one rainfall-dominated basin (Alapaha River at Statenville, Georgia) and three snowmelt-dominated basins (Animas River at Durango. Colorado; east fork of the Carson River near Gardnerville, Nevada: and Cle Elum River near Roslyn, Washington). For comparison purposes, spatially averaged daily datasets of precipitation and maximum and minimum temperature were developed from measured data for each basin. These datasets included precipitation and temperature data for all stations (hereafter, All-Sta) located within the area of the RegCM2 output used for each basin, but excluded station data used to calibrate the hydrologic model. Both the RegCM2 output and All-Sta data capture the gross aspects of the seasonal cycles of precipitation and temperature. However, in all four basins, the RegCM2- and All-Sta-based simulations of runoff show little skill on a daily basis [Nash-Sutcliffe (NS) values range from 0.05 to 0.37 for RegCM2 and -0.08 to 0.65 for All-Sta]. When the precipitation and temperature biases are corrected in the RegCM2 output and All-Sta data (Bias-RegCM2 and Bias-All, respectively) the accuracy of the daily runoff simulations improve dramatically for the snowmelt-dominated basins (NS values range from 0.41 to 0.66 for RegCM2 and 0.60 to 0.76 for All-Sta). In the rainfall-dominated basin, runoff simulations based on the Bias-RegCM2 output show no skill (NS value of 0.09) whereas Bias-All simulated runoff improves (NS value improved from - 0.08 to 0.72). These results indicate that measured data at the coarse resolution of the RegCM2 output can be made appropriate for basin-scale modeling through bias correction (essentially a magnitude correction). However, RegCM2 output, even when bias corrected, does not contain the day-to-day variability present in the All-Sta dataset that is necessary for basin-scale modeling. Future work is warranted to identify the causes for systematic biases in RegCM2 simulations, develop methods to remove the biases, and improve RegCM2 simulations of daily variability in local climate.

Enhancing the ATIC Charge Resolution

NASA Technical Reports Server (NTRS)

Guzik, T. G.; Adams, J. H., Jr.; Ahn, H. S.; Bashindzhagyan, G. L.; Batkov, K. E.; Chang, J.; Christl, M.; Fazely, A. R.; Ganel, O.; Gunashingha, R. M.

2006-01-01

The Advanced Thin Ionization Calorimeter (ATIC) experiment measures the energy spectra of elements, from H to Fe, in the energy region from about 100 GeV to tens of TeV. The ATIC instrument was flown twice in long-duration balloon flights around the South Pole; the ATIC-1 test flight during Dec. 2000 - Jan. 2001 and the ATIC-2 science flight during Dec. 2002 - Jan. 2003. Analyses of both datasets have, to date, relied upon the highly segmented Silicon Matrix (SiM) detector to separate the incident cosmic ray from the calorimeter backscatter and to identify the charge. This method has worked well, enabling ATIC to separate protons from helium and to resolve all the major species up through iron. This charge resolution can be significantly improved by restricting the analysis to particle trajectories that pass through two SiM pixels at the cost of using only a fraction of the potential instrument geometry. However, immediately below the SiM is the two layer SI hodoscope (x, y) consisting of Bicron BC-408 plastic scintillator 2 cm wide, 1 cm thick, 88.2 cm long strips viewed by Hamamatsu R5611 photomultiplier tubes on each end of each strip. The primary purpose of the ATIC hodoscopes is to provide a fast trigger, and each hodoscope includes two crossed layers of strips (42 per layer in the case of Sl) providing supplemental particle trajectory information. The hodoscope readout electronics were designed to provide reasonable charge resolution over the dynamic range from protons through iron. This presentation discusses the S 1 hodoscope energy deposit calibrations, examines the charge resolution possible with this detector and investigates combining the S1 and SiM charge measurements to improve the overall ATIC charge resolution while minimizing degradation of the instrument geometry.

Ultrafast mid-infrared spectroscopy by chirped pulse upconversion in 1800-1000cm(-1) region.

PubMed

Zhu, Jingyi; Mathes, Tilo; Stahl, Andreas D; Kennis, John T M; Groot, Marie Louise

2012-05-07

Broadband femtosecond mid-infrared pulses can be converted into the visible spectral region by chirped pulse upconversion. We report here the upconversion of pump probe transient signals in the frequency region below 1800cm(-1), using the nonlinear optical crystal AgGaGeS4, realizing an important expansion of the application range of this method. Experiments were demonstrated with a slab of GaAs, in which the upconverted signals cover a window of 120cm(-1), with 1.5cm(-1) resolution. In experiments on the BLUF photoreceptor Slr1694, signals below 1 milliOD were well resolved after baseline correction. Possibilities for further optimization of the method are discussed. We conclude that this method is an attractive alternative for the traditional MCT arrays used in most mid-infrared pump probe experiments.

Estimation of sea surface temperature from remote measurements in the 11-13 micron window region

NASA Technical Reports Server (NTRS)

Prabhakara, C.; Conrath, B. J.; Kunde, V. G.

1972-01-01

The Nimbus-4 IRIS data was examined in the spectral region 775 to 1250/cm (8-13 microns) for useful information to determine the sea surface temperature. The high spectral resolution data of IRIS was degraded to low resolution by averaging to simulate a multi-channel radiometer in the window region. These simulated data show that within the region 775-975/cm (12.9-10.25 microns) the brightness temperatures are linearly related to the absorption parameters. Such a linear relationship is observed over cloudy as well as clear regions and over a wide range of latitudes. From this linear relationship it is feasible to correct for the atmospheric attenuation and get the sea surface temperature, accurate to within 1 K, in a cloud free field of view. The information about the cloud cover is taken from the TV pictures and BUV albedo measurements on board the Nimbus-4 satellite.

Phase Contrast Imaging on the HL-2A Tokamak

NASA Astrophysics Data System (ADS)

Yu, Yi; Gong, Shaobo; Xu, Min; Jiang, Wei; Zhong, Wulv; Shi, Zhongbin; Wang, Huajie; Wu, Yifan; Yuan, Boda; Lan, Tao; Ye, Minyou; Duan, Xuru; HL-2A Team

2016-10-01

In this article we present the design of a phase contrast imaging (PCI) system on the HL-2A tokamak. This diagnostic is developed to infer line integrated plasma density fluctuations by measuring the phase shift of an expanded CO2 laser beam passing through magnetically confined high temperature plasmas. This system is designed to diagnose plasma density fluctuations with the maximum wavenumber of 66 cm-1. The designed wavenumber resolution is 2.09cm-1, and the time resolution is higher than 0.2 μs. The broad kρs ranging from 0.34 to 13.37 makes it suitable for turbulence measurement. An upgraded PCI system is also discussed, which is designed for the HL-2M tokamak. Supported by the National Magnetic Confinement Fusion Energy Research Project (Grant No. 2015GB120002), the National Natural Science Foundation of China (Grant No. 11375053, 11105144, 10905057, 11535013).

A Martian PFS average spectrum: Comparison with ISO SWS

NASA Astrophysics Data System (ADS)

Formisano, V.; Encrenaz, T.; Fonti, S.; Giuranna, M.; Grassi, D.; Hirsh, H.; Khatuntsev, I.; Ignatiev, N.; Lellouch, E.; Maturilli, A.; Moroz, V.; Orleanski, P.; Piccioni, G.; Rataj, M.; Saggin, B.; Zasova, L.

2005-08-01

The evaluation of the planetary Fourier spectrometer performance at Mars is presented by comparing an average spectrum with the ISO spectrum published by Lellouch et al. [2000. Planet. Space Sci. 48, 1393.]. First, the average conditions of Mars atmosphere are compared, then the mixing ratios of the major gases are evaluated. Major and minor bands of CO 2 are compared, from the point of view of features characteristics and bands depth. The spectral resolution is also compared using several solar lines. The result indicates that PFS radiance is valid to better than 1% in the wavenumber range 1800-4200 cm -1 for the average spectrum considered (1680 measurements). The PFS monochromatic transfer function generates an overshooting on the left-hand side of strong narrow lines (solar or atmospheric). The spectral resolution of PFS is of the order of 1.3 cm -1 or better. A large number of narrow features to be identified are discovered.

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.

High-Resolution Triple Resonance Autoionization of Uranium Isotopes

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

Schumann, Philipp G.; Wendt, K; Bushaw, Bruce A.

2005-11-01

The near-threshold autoionization (AI) spectrum of uranium has been investigated by triple-resonance excitation with single-mode continuous lasers. Spectra were recorded over the first {approx}30 cm-1 above the first ionization limit at a resolution of 3x10-4 cm 1 using intermediate states with different J values (6, 7, 8) to assign AI level total angular momentum JAI = 5 to 9. Resonances with widths ranging from 8 MHz to 30 GHz were observed; the strongest ones have JAI = 9 and widths of {approx} 60 MHz. Hyperfine structures for 235U and isotope shifts for 234,235U have been measured in the two intermediatemore » levels and in the final AI level for the most favorable excitation path. These measurements were performed using aqueous samples containing sub-milligram quantities of uranium at natural isotopic abundances, indicating the potential of this approach for trace isotope ratio determinations.« less

A maximum likelihood method for high resolution proton radiography/proton CT

NASA Astrophysics Data System (ADS)

Collins-Fekete, Charles-Antoine; Brousmiche, Sébastien; Portillo, Stephen K. N.; Beaulieu, Luc; Seco, Joao

2016-12-01

Multiple Coulomb scattering (MCS) is the largest contributor to blurring in proton imaging. In this work, we developed a maximum likelihood least squares estimator that improves proton radiography’s spatial resolution. The water equivalent thickness (WET) through projections defined from the source to the detector pixels were estimated such that they maximizes the likelihood of the energy loss of every proton crossing the volume. The length spent in each projection was calculated through the optimized cubic spline path estimate. The proton radiographies were produced using Geant4 simulations. Three phantoms were studied here: a slanted cube in a tank of water to measure 2D spatial resolution, a voxelized head phantom for clinical performance evaluation as well as a parametric Catphan phantom (CTP528) for 3D spatial resolution. Two proton beam configurations were used: a parallel and a conical beam. Proton beams of 200 and 330 MeV were simulated to acquire the radiography. Spatial resolution is increased from 2.44 lp cm-1 to 4.53 lp cm-1 in the 200 MeV beam and from 3.49 lp cm-1 to 5.76 lp cm-1 in the 330 MeV beam. Beam configurations do not affect the reconstructed spatial resolution as investigated between a radiography acquired with the parallel (3.49 lp cm-1 to 5.76 lp cm-1) or conical beam (from 3.49 lp cm-1 to 5.56 lp cm-1). The improved images were then used as input in a photon tomography algorithm. The proton CT reconstruction of the Catphan phantom shows high spatial resolution (from 2.79 to 5.55 lp cm-1 for the parallel beam and from 3.03 to 5.15 lp cm-1 for the conical beam) and the reconstruction of the head phantom, although qualitative, shows high contrast in the gradient region. The proposed formulation of the optimization demonstrates serious potential to increase the spatial resolution (up by 65 % ) in proton radiography and greatly accelerate proton computed tomography reconstruction.

A maximum likelihood method for high resolution proton radiography/proton CT.

PubMed

Collins-Fekete, Charles-Antoine; Brousmiche, Sébastien; Portillo, Stephen K N; Beaulieu, Luc; Seco, Joao

2016-12-07

Multiple Coulomb scattering (MCS) is the largest contributor to blurring in proton imaging. In this work, we developed a maximum likelihood least squares estimator that improves proton radiography's spatial resolution. The water equivalent thickness (WET) through projections defined from the source to the detector pixels were estimated such that they maximizes the likelihood of the energy loss of every proton crossing the volume. The length spent in each projection was calculated through the optimized cubic spline path estimate. The proton radiographies were produced using Geant4 simulations. Three phantoms were studied here: a slanted cube in a tank of water to measure 2D spatial resolution, a voxelized head phantom for clinical performance evaluation as well as a parametric Catphan phantom (CTP528) for 3D spatial resolution. Two proton beam configurations were used: a parallel and a conical beam. Proton beams of 200 and 330 MeV were simulated to acquire the radiography. Spatial resolution is increased from 2.44 lp cm -1 to 4.53 lp cm -1 in the 200 MeV beam and from 3.49 lp cm -1 to 5.76 lp cm -1 in the 330 MeV beam. Beam configurations do not affect the reconstructed spatial resolution as investigated between a radiography acquired with the parallel (3.49 lp cm -1 to 5.76 lp cm -1 ) or conical beam (from 3.49 lp cm -1 to 5.56 lp cm -1 ). The improved images were then used as input in a photon tomography algorithm. The proton CT reconstruction of the Catphan phantom shows high spatial resolution (from 2.79 to 5.55 lp cm -1 for the parallel beam and from 3.03 to 5.15 lp cm -1 for the conical beam) and the reconstruction of the head phantom, although qualitative, shows high contrast in the gradient region. The proposed formulation of the optimization demonstrates serious potential to increase the spatial resolution (up by 65[Formula: see text]) in proton radiography and greatly accelerate proton computed tomography reconstruction.

LSNR Airborne LIDAR Mapping System Design and Early Results (Invited)

NASA Astrophysics Data System (ADS)

Shrestha, K.; Carter, W. E.; Slatton, K. C.

2009-12-01

Low signal-to-noise ratio (LSNR) detection techniques allow for implementation of airborne light detection and range (LIDAR) instrumentation aboard platforms with prohibitive power, size, and weight restrictions. The University of Florida has developed the Coastal Area Tactical-mapping System (CATS), a prototype LSNR LIDAR system capable of single photon laser ranging. CATS is designed to operate in a fixed-wing aircraft flying 600 m above ground level, producing 532 nm, 480 ps, 3 μJ output pulses at 8 kHz. To achieve continuous coverage of the terrain with 20 cm spatial resolution in a single pass, a 10x10 array of laser beamlets is scanned. A Risley prism scanner (two rotating V-coated optical wedges) allows the array of laser beamlets to be deflected in a variety of patterns, including conical, spiral, and lines at selected angles to the direction of flight. Backscattered laser photons are imaged onto a 100 channel (10x10 segmented-anode) photomultiplier tube (PMT) with a micro-channel plate (MCP) amplifier. Each channel of the PMT is connected to a multi-stop 2 GHz event timer. Here we report on tests in which ranges for known targets were accumulated for repeated laser shots and statistical analyses were applied to evaluate range accuracy, minimum separation distance, bathymetric mapping depth, and atmospheric scattering. Ground-based field test results have yielded 10 cm range accuracy and sub-meter feature identification at variable scan settings. These experiments also show that a secondary surface can be detected at a distance of 15 cm from the first. Range errors in secondary surface identification for six separate trials were within 7.5 cm, or within the timing resolution limit of the system. Operating at multi-photon sensitivity may have value for situations in which high ambient noise precludes single-photon sensitivity. Low reflectivity targets submerged in highly turbid waters can cause detection issues. CATS offers the capability to adjust the sensitivity of the sensor by changing the PMT supply voltage. For heavily turbid water, the multi-photon state (2300 V, 2.5*10^5 gain) was not sufficient for feature identification. Extraction of the bottom signal in a heavily turbid suspension necessitated maximum MCP-PMT gain (2500 V, 8*10^5 gain). Extrapolation of bathymetric test results suggest that the density of data points from the sea bottom should be sufficient to establish near-shore depths (up to 5 m) at a spatial resolution of 1 meter, in moderately turbid water. Initial airborne tests over fresh water lakes in central Florida indicate that scan patterns containing near nadir laser points produce strong returns from the surface of the water that cause oscillations in the PMT—preventing the detection of the lake bottom in shallow clear water. These results suggest that it may be necessary to tilt the sensor head in its mount, or use a scan pattern that does not include nadir points, such as a circular scan, for bathymetric mapping. Additional tests are ongoing to optimize the performance of the CATS LSNR airborne LIDAR system for both high spatial resolution terrain mapping and shallow water bathymetric mapping.

Role of resolution in regional climate change projections over China

NASA Astrophysics Data System (ADS)

Shi, Ying; Wang, Guiling; Gao, Xuejie

2017-11-01

This paper investigates the sensitivity of projected future climate changes over China to the horizontal resolution of a regional climate model RegCM4.4 (RegCM), using RCP8.5 as an example. Model validation shows that RegCM performs better in reproducing the spatial distribution and magnitude of present-day temperature, precipitation and climate extremes than the driving global climate model HadGEM2-ES (HadGEM, at 1.875° × 1.25° degree resolution), but little difference is found between the simulations at 50 and 25 km resolutions. Comparison with observational data at different resolutions confirmed the added value of the RCM and finer model resolutions in better capturing the probability distribution of precipitation. However, HadGEM and RegCM at both resolutions project a similar pattern of significant future warming during both winter and summer, and a similar pattern of winter precipitation changes including dominant increase in most areas of northern China and little change or decrease in the southern part. Projected precipitation changes in summer diverge among the three models, especially over eastern China, with a general increase in HadGEM, little change in RegCM at 50 km, and a mix of increase and decrease in RegCM at 25 km resolution. Changes of temperature-related extremes (annual total number of daily maximum temperature > 25 °C, the maximum value of daily maximum temperature, the minimum value of daily minimum temperature in the three simulations especially in the two RegCM simulations are very similar to each other; so are the precipitation-related extremes (maximum consecutive dry days, maximum consecutive 5-day precipitation and extremely wet days' total amount). Overall, results from this study indicate a very low sensitivity of projected changes in this region to model resolution. While fine resolution is critical for capturing the spatial variability of the control climate, it may not be as important for capturing the climate response to homogeneous forcing (in this case greenhouse gas concentration changes).

The hard X-ray burst spectrometer on the solar maximum mission

NASA Technical Reports Server (NTRS)

Orwig, L. E.; Frost, K. J.; Dennis, B. R.

1979-01-01

The primary scientific objective of the spectrometer is to provide a greater understanding of the role of energetic electrons in solar flares. This will be achieved by observations of high energy X-rays in the energy range from 20 to 200 keV with time resolution of 0.128s on a continuous basis and as short as 1 ms for limited intervals. The X-ray detector is an actively shielded CsI(Na) crystal with a thickness of 0.635 cm and a sensitive area of 71 sq cm. In the first year after launch, it is expected that approximately 1000 flares above the sensitivity threshold of 0.2 photons/(sq cm s) lasting for one second, will be detected.

Single mode, short cavity, Pb-salt diode lasers operating in the 5, 10, and 30-microns spectral regions

NASA Technical Reports Server (NTRS)

Linden, K. J.

1985-01-01

Pb-salt diode lasers are being used as frequency-tunable infrared sources in high resolution spectroscopy and heterodyne detection applications. Recent advances in short cavity, stripe-geometry laser configurations have led to significant increases in maximum CW operating temperature, single mode operation, and increased single mode tuning range. This paper describes short cavity, stripe geometry lasers operating in the 5, 10, and 30-microns spectral regions, with single mode tuning ranges of over 6/cm.

A Unique, Optically Accessible Flame Tube Facility for Lean Combustor Studies

NASA Technical Reports Server (NTRS)

Hicks, Yolanda R.; Locke, Randy J.; Wey, Chowen C.; Bianco, Jean

1995-01-01

A facility that allows interrogation of combusting flows by advanced diagnostic methods and instrumentation has been developed at the NASA Lewis Research Center. An optically accessible flame tube combustor is described which has high temperature, pressure, and air flow capabilities. The windows in the combustor measure 3.8 cm axially by 5.1 cm radially, providing 67% optical access to the 7.6 cm x 7.6 cm cross section flow chamber. Advanced gas analysis instrumentation is available through a gas chromatography/mass spectrometer system (GC/MS), which has on-line capability for heavy hydrocarbon measurement with resolution to the parts per billion level. The instrumentation allows one to study combusting flows and combustor subcomponents, such as fuel injectors and air swirlers. Planar Laser Induced Fluorescence (PLIF) can measure unstable combustion species, which cannot be obtained with traditional gas sampling. This type of data is especially useful to combustion modellers. The optical access allows measurements to have high spatial and temporal resolution. GC/MS data and PLIF images of OH- are presented from experiments using a lean direct injection (LDI) combustor burning Jet-A fuel at inlet temperatures ranging from 810 K to 866 K, combustor pressures up to 1380 kPa, and equivalence ratios from 0.41 to 0.59.

Late Pleistocene and Holocene paleoclimate and alpine glacier fluctuations recorded by high-resolution grain-size data from an alpine lake sediment core, Wind River Range, Wyoming, USA

NASA Astrophysics Data System (ADS)

Thompson Davis, P.; Machalett, Björn; Gosse, John

2013-04-01

Varved lake sediments, which provide ideal high-resolution climate proxies, are not commonly available in many geographic areas over long time scales. This paper utilizes high-resolution grain-size analyses (n = 1040) from a 520-cm long sediment core from Lower Titcomb Lake (LTL), which lies just outside the type Titcomb Basin (TTB) moraines in the Wind River Range, Wyoming. The TTB moraines lie between Lower Titcomb Lake and Upper Titcomb Lake (UTL), about 3 km beyond, and 200 m lower than the modern glacier margin and Gannett Peak (Little Ice Age) moraines in the basin. Based on cosmogenic exposure dating, the TTB moraines are believed to be Younger Dryas (YD) age (Gosse et al., 1995) and lie in a geomorphic position similar to several other outer cirque moraines throughout the western American Cordillera. Until recently, many of these outer cirque moraines were believed to be Neoglacial age. The sediment core discussed here is one of five obtained from the two Titcomb Lakes, but is by the far the longest with the oldest sediment depositional record. Two AMS radiocarbon ages from the 445- and 455-cm core depths (about 2% loss on ignition, LOI) suggest that the lake basin may have been ice-free as early as 16.1 or even 16.8 cal 14C kyr, consistent with 10Be and 26Al exposure ages from boulders and bedrock surfaces outside the TTB moraines. The 257-cm depth in the core marks an abrupt transition from inorganic, sticky gray silt below (<1% LOI) to more organic, less sticky, light brown silt above (4-10% LOI). Eight AMS radiocarbon ages on bulk sediment and macrofossils date the transition to about 11.6 cal 14C kyr. Thus, sampling resolution above the transition is about 22.57 yr and below the transition is about 12.56 yr, consistent with a decreased sediment accumulation rate in LTL when Younger Dryas ice pulled back from the TTB moraines opening up UTL as a sediment depositional basin. The presented high-resolution grain size record reveals amplitudes and other structural features similar to delta 18O records from deep-lake ostracods in southern Germany, the Greenland ice core record, and speleothems in China. Major increases in the 2 - 8 µm grain size fraction indicative of increased glacier rock flour production between the 257 and 466 cm core depths appear to be roughly correlative with the YD-Alleröd-Bölling-Meiendorf-Heinrich 1 climate events recognized in other terrestrial records and Northern Atlantic Ocean marine cores, but provide much higher resolution than most of those records from a climate-sensitive alpine region in North America.

The AGILE silicon tracker: testbeam results of the prototype silicon detector

NASA Astrophysics Data System (ADS)

Barbiellini, G.; Fedel, G.; Liello, F.; Longo, F.; Pontoni, C.; Prest, M.; Tavani, M.; Vallazza, E.

2002-09-01

AGILE (Light Imager for Gamma-ray Astrophysics) is a small scientific satellite for the detection of cosmic γ-ray sources in the energy range 30MeV-50GeV with a very large field of view (1/4 of the sky). It is planned to be operational in the years 2003-2006, a period in which no other γ-ray mission in the same energy range is foreseen. The heart of the AGILE scientific instrument is a silicon-tungsten tracker made of 14 planes of single sided silicon detectors for a total of 43000 readout channels. Each detector has a dimension of 9.5×9.5cm2 and a thickness of 410μm. We present here a detailed description of the performance of the detector prototype during a testbeam period at the CERN PS in May 2000. The Tracker performance is described in terms of position resolution and signal-to-noise ratio for on and off-axis incident charged particles. The measured 40μm resolution for a large range of incident angles will provide an excellent angular resolution for cosmic γ-ray imaging.

Miniature Raman spectrometer development

NASA Astrophysics Data System (ADS)

Bonvallet, Joseph; Auz, Bryan; Rodriguez, John; Olmstead, Ty

2018-02-01

The development of techniques to rapidly identify samples ranging from, molecule and particle imaging to detection of high explosive materials, has surged in recent years. Due to this growing want, Raman spectroscopy gives a molecular fingerprint, with no sample preparation, and can be done remotely. These systems can be small, compact, lightweight, and with a user interface that allows for easy use and sample identification. Ocean Optics Inc. has developed several systems that would meet all these end user requirements. This talk will describe the development of different Ocean Optics Inc miniature Raman spectrometers. The spectrometer on a phone (SOAP) system was designed using commercial off the shelf (COTS) components, in a rapid product development cycle. The footprint of the system measures 40x40x14 mm (LxWxH) and was coupled directly to the cell phone detector camera optics. However, it gets roughly only 40 cm-1 resolution. The Accuman system is the largest (290x220X100 mm) of the three, but uses our QEPro spectrometer and get 7-11 cm-1 resolution. Finally, the HRS-30 measuring 165x85x40 mm is a combination of the other two systems. This system uses a modified EMBED spectrometer and gets 7-12 cm-1 resolution. Each of these units uses a peak matching algorithm that then correlates the results to the pre-loaded and customizable spectral libraries.

Continuous wave external-cavity quantum cascade laser-based high-resolution cavity ring-down spectrometer for ultrasensitive trace gas detection.

PubMed

De, Anulekha; Banik, Gourab Dutta; Maity, Abhijit; Pal, Mithun; Pradhan, Manik

2016-05-01

A high-resolution cavity ring-down spectroscopic (CRDS) system based on a continuous wave (cw) mode-hop-free (MHF) external-cavity quantum cascade laser (EC-QCL) operating at λ∼5.2  μm has been developed for ultrasensitive detection of nitric oxide (NO). We report the performance of the high-resolution EC-QCL based cw-CRDS instrument by measuring the rotationally resolved Λ-doublet e and f components of the P(7.5) line in the fundamental band of NO at 1850.169  cm^-1 and 1850.179  cm^-1. A noise-equivalent absorption coefficient of 1.01×10^-9  cm^-1  Hz^-1/2 was achieved based on an empty cavity ring-down time of τ₀=5.6  μs and standard deviation of 0.11% with averaging of six ring-down time determinations. The CRDS sensor demonstrates the advantages of measuring parts per billion NO concentrations in N₂, as well as in human breath samples with ultrahigh sensitivity and specificity. The CRDS system could also be generalized to measure simultaneously many other trace molecular species within the broad tuning range of cw EC-QCL, as well as for studying the rotationally resolved hyperfine structures.

D/H RATIO OF TITAN FROM OBSERVATIONS OF THE CASSINI/COMPOSITE INFRARED SPECTROMETER

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

Abbas, M. M.; LeClair, A.; Kandadi, H., E-mail: mian.m.abbas@nasa.go, E-mail: andre.c.leClair@nasa.go, E-mail: harini.kandadi@uah.ed

2010-01-01

The Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft, launched in 1997 October and inserted into Saturn's orbit in 2004 July for exploration of the Saturnian system, has been making observations of Titan during its close flybys. The infrared spectra of Titan observed over a wide range of latitudes cover the 10-1400 cm{sup -1} spectral region with variable apodized resolutions from 0.53 to 15 cm{sup -1}. The spectra exhibit features of the nu{sub 4} band of methane (CH{sub 4}) in the 1300 cm{sup -1} region, and the deuterated isotope of methane (CH{sub 3}D) centered around 1156 cm{sup -1}, along withmore » features of many trace constituents in other spectral regions, comprising hydrocarbons and nitriles in Titan's atmosphere. An analysis of the observed infrared spectra in the 1300 cm{sup -1} and 1156 cm{sup -1} regions, respectively, permits retrieval of the thermal structure and the CH{sub 3}D distributions of Titan's atmosphere. In this paper, we present a comprehensive analysis of the CIRS infrared spectra for retrieval of the CH{sub 3}D abundance and the corresponding D/H ratio in Titan's atmosphere. The analysis is based on the 0.53 cm{sup -1} resolution infrared spectra obtained during the Titan flybys from 2004 July 3 to 2008 May 28 over a range of latitudes extending from 74.{sup 0}4 N to 84.{sup 0}9 S. Using the CH{sub 4} mixing ratio of 1.4 x 10{sup -2} as measured by the Gas Chromatograph and Mass Spectrometer on the Huygens probe on the Cassini mission, we determine the D/H ratio of Titan as (1.58 +- 0.16) x 10{sup -4}, where the 1sigma uncertainty includes the standard deviation due to spectral noise and the estimated errors arising from uncertainties in the temperature retrieval, the mixing ratio of CH{sub 4}, and the spectral line parameters. Comparison of this value with the previously measured values for Titan as well as in other astrophysical sources, and its possible implications are discussed.« less

3D electrode localization on wireless sensor networks for wearable BCI.

PubMed

Figueiredo, C P; Dias, N S; Hoffmann, K P; Mendes, P M

2008-01-01

This paper presents a solution for electrode localization on wearable BCI radio-enabled electrodes. Electrode positioning is a common issue in any electrical physiological recording. Although wireless node localization is a very active research topic, a precise method with few centimeters of range and a resolution in the order of millimeters is still to be found, since far-field measurements are very prone to error. The calculation of 3D coordinates for each electrode is based on anchorless range-based localization algorithms such as Multidimensional Scaling and Self-Positioning Algorithm. The implemented solution relies on the association of a small antenna to measure the magnetic field and a microcontroller to each electrode, which will be part of the wireless sensor network module. The implemented solution is suitable for EEG applications, namely the wearable BCI, with expected range of 20 cm and resolution of 5 mm.

High accuracy LADAR scene projector calibration sensor development

NASA Astrophysics Data System (ADS)

Kim, Hajin J.; Cornell, Michael C.; Naumann, Charles B.; Bowden, Mark H.

2008-04-01

A sensor system for the characterization of infrared laser radar scene projectors has been developed. Available sensor systems do not provide sufficient range resolution to evaluate the high precision LADAR projector systems developed by the U.S. Army Research, Development and Engineering Command (RDECOM) Aviation and Missile Research, Development and Engineering Center (AMRDEC). With timing precision capability to a fraction of a nanosecond, it can confirm the accuracy of simulated return pulses from a nominal range of up to 6.5 km to a resolution of 4cm. Increased range can be achieved through firmware reconfiguration. Two independent amplitude triggers measure both rise and fall time providing a judgment of pulse shape and allowing estimation of the contained energy. Each return channel can measure up to 32 returns per trigger characterizing each return pulse independently. Currently efforts include extending the capability to 8 channels. This paper outlines the development, testing, capabilities and limitations of this new sensor system.

Dielectric method of high-resolution gas hydrate estimation

NASA Astrophysics Data System (ADS)

Sun, Y. F.; Goldberg, D.

2005-02-01

In-situ dielectric properties of natural gas hydrate are measured for the first time in the Mallik 5L-38 Well in the Mackenzie Delta, Canada. The average dielectric constant of the hydrate zones is 9, ranging from 5 to 20. The average resistivity is >5 ohm.m in the hydrate zones, ranging from 2 to 10 ohm.m at a 1.1 GHz dielectric tool frequency. The dielectric logs show similar trends with sonic and induction resistivity logs, but exhibits inherently higher vertical resolution (<5 cm). The average in-situ hydrate saturation in the well is about 70%, ranging from 20% to 95%. The dielectric estimates are overall in agreement with induction estimates but the induction log tends to overestimate hydrate content up to 15%. Dielectric estimates could be used as a better proxy of in-situ hydrate saturation in modeling hydrate dynamics. The fine-scale structure in hydrate zones could help reveal hydrate formation history.

High resolution extensometer based on optical encoder for measurement of small landslide displacements

NASA Astrophysics Data System (ADS)

Afandi, M. I.; Adinanta, H.; Setiono, A.; Qomaruddin; Widiyatmoko, B.

2018-03-01

There are many ways to measure landslide displacement using sensors such as multi-turn potentiometer, fiber optic strain sensor, GPS, geodetic measurement, ground penetrating radar, etc. The proposed way is to use an optical encoder that produces pulse signal with high stability of measurement resolution despite voltage source instability. The landslide measurement using extensometer based on optical encoder has the ability of high resolution for wide range measurement and for a long period of time. The type of incremental optical encoder provides information about the pulse and direction of a rotating shaft by producing quadrature square wave cycle per increment of shaft movement. The result of measurement using 2,000 pulses per resolution of optical encoder has been obtained. Resolution of extensometer is 36 μm with speed limit of about 3.6 cm/s. System test in hazard landslide area has been carried out with good reliability for small landslide displacement monitoring.

Study of Image Quality From CT Scanner Multi-Detector by using Americans College of Radiology (ACR) Phantom

NASA Astrophysics Data System (ADS)

Mulyadin; Dewang, Syamsir; Abdullah, Bualkar; Tahir, Dahlang

2018-03-01

In this study, the image quality of CT scan using phantom American College of Radiology (ACR) was determined. Scanning multidetector CT is used to know the image quality parameters by using a solid phantom containing four modules and primarily from materials that are equivalent to water. Each module is 4 cm in diameter and 20 cm in diameter. There is white alignment marks painted white to reflect the alignment laser and there are also “HEAD”, “FOOT”, and “TOP” marks on the phantom to help align. This test obtains CT images of each module according to the routine inspection protocol of the head. Acceptance of image quality obtained for determination: CT Number Accuracy (CTN), CT Number Uniformity and Noise, Linearity CT Number, Slice Technique, Low Contrast Resolution and High Contrast Resolution represent image quality parameters. In testing CT Number Accuracy (CTN), CT Uniform number and Noise are in the range of tolerable values allowed. In the test, Linearity CT Number obtained correlation value above 0.99 is the relationship between electron density and CT Number. In a low contrast resolution test, the smallest contrast groups are visible. In contrast, the high resolution is seen up to 7 lp/cm. The quality of GE CT Scan is very high, as all the image quality tests obtained are within the tolerance brackets of values permitted by the Nuclear Power Control Agency (BAPETEN). Image quality test is a way to get very important information about the accuracy of snoring result by using phantom ACR.

Analysis of the Fourier Spectrum of the ν2 Inversion Band of the 15NHD2 Molecule

NASA Astrophysics Data System (ADS)

Fomchenko, A. L.; Belova, A. S.; Bekhtereva, E. S.; Kwabia Tchana, F.

2018-06-01

To determine high-resolution rovibrational levels of the inversion vibrational (v2 = 1) state of the 15NHD2 molecule, the Fourier spectrum in the range from 650 to 1150 cm-1 is studied. The data obtained are used to determine the parameters of the effective Hamiltonian of the examined molecule.

Potential High Resolution Dosimeters For MRT

NASA Astrophysics Data System (ADS)

Bräuer-Krisch, E.; Rosenfeld, A.; Lerch, M.; Petasecca, M.; Akselrod, M.; Sykora, J.; Bartz, J.; Ptaszkiewicz, M.; Olko, P.; Berg, A.; Wieland, M.; Doran, S.; Brochard, T.; Kamlowski, A.; Cellere, G.; Paccagnella, A.; Siegbahn, E. A.; Prezado, Y.; Martinez-Rovira, I.; Bravin, A.; Dusseau, L.; Berkvens, P.

2010-07-01

Microbeam Radiation Therapy (MRT) uses highly collimated, quasi-parallel arrays of X-ray microbeams of 50-600 keV, produced by 2nd and 3rd generation synchrotron sources, such as the National Synchrotron Light Source (NSLS) in the U.S., and the European Synchrotron Radiation Facility (ESRF) in France, respectively. High dose rates are necessary to deliver therapeutic doses in microscopic volumes, to avoid spreading of the microbeams by cardiosynchronous movement of the tissues. A small beam divergence and a filtered white beam spectrum in the energy range between 30 and 250 keV results in the advantage of steep dose gradients with a sharper penumbra than that produced in conventional radiotherapy. MRT research over the past 20 years has allowed a vast number of results from preclinical trials on different animal models, including mice, rats, piglets and rabbits. Microbeams in the range between 10 and 100 micron width show an unprecedented sparing of normal radiosensitive tissues as well as preferential damage to malignant tumor tissues. Typically, MRT uses arrays of narrow (˜25-100 micron-wide) microplanar beams separated by wider (100-400 microns centre-to-centre, c-t-c) microplanar spaces. We note that thicker microbeams of 0.1-0.68 mm used by investigators at the NSLS are still called microbeams, although some invesigators in the community prefer to call them minibeams. This report, however, limits it discussion to 25-100 μm microbeams. Peak entrance doses of several hundreds of Gy are surprisingly well tolerated by normal tissues. High resolution dosimetry has been developed over the last two decades, but typical dose ranges are adapted to dose delivery in conventional Radiation Therapy (RT). Spatial resolution in the sub-millimetric range has been achieved, which is currently required for quality assurance measurements in Gamma-knife RT. Most typical commercially available detectors are not suitable for MRT applications at a dose rate of 16000 Gy/s, micron resolution and a dose range over several orders of magnitude. This paper will give an overview of all dosimeters tested in the past at the ESRF with their advantages and drawbacks. These detectors comprise: Ionization chambers, Alanine Dosimeters, MOSFET detectors, Gafchromic® films, Radiochromic polymers, TLDs, Polymer gels, Fluorescent Nuclear Track Detectors (Al2O3:C, Mg single crystal detectors), OSL detectors and Floating Gate-based dosimetry system. The aim of such a comparison shall help with a decision on which of these approaches is most suitable for high resolution dose measurements in MRT. The principle of these detectors will be presented including a comparison for some dosimeters exposed with the same irradiation geometry, namely a 1×1 cm5 field size with microbeam exposures at the surface, 0.1 cm and 1 cm in depth of a PMMA phantom. For these test exposures, the most relevant irradiation parameters for future clinical trials have been chosen: 50 micron FWHM and 400 micron c-t-c distance. The experimental data are compared with Monte Carlo calculations.

Development of a temperature gradient focusing method for in situ extraterrestrial biomarker analysis.

PubMed

Danger, Grégoire; Ross, David

2008-08-01

Scanning temperature gradient focusing (TGF) is a recently described technique for the simultaneous concentration and separation of charged analytes. It allows for high analyte peak capacities and low LODs in microcolumn electrophoretic separations. In this paper, we present the application of scanning TGF for chiral separations of amino acids. Using a mixture of seven carboxyfluorescein succinimidyl ester-labeled amino acids (including five chiral amino acids) which constitute the Mars7 standard, we show that scanning TGF is a very simple and efficient method for chiral separations. The modulation of TGF separation parameters (temperature window, pressure scan rate, temperature range, and chiral selector concentration) allows optimization of peak efficiencies and analyte resolutions. The use of hydroxypropyl-beta-CD at low concentration (1-5 mmol/L) as a chiral selector, with an appropriate pressure scan rate ( -0.25 Pa/s) and with a low temperature range (3-25 degrees C over 1 cm) provided high resolution between enantiomers (Rs >1.5 for each pair of enantiomers) using a short, 4 cm long capillary. With these new results, the scanning TGF method appears to be a viable method for in situ trace biomarker analysis for future missions to Mars or other solar system bodies.

SU-E-J-197: Investigation of Microsoft Kinect 2.0 Depth Resolution for Patient Motion Tracking

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

Silverstein, E; Snyder, M

2015-06-15

Purpose: Investigate the use of the Kinect 2.0 for patient motion tracking during radiotherapy by studying spatial and depth resolution capabilities. Methods: Using code written in C#, depth map data was abstracted from the Kinect to create an initial depth map template indicative of the initial position of an object to be compared to the depth map of the object over time. To test this process, simple setup was created in which two objects were imaged: a 40 cm × 40 cm board covered in non reflective material and a 15 cm × 26 cm textbook with a slightly reflective,more » glossy cover. Each object, imaged and measured separately, was placed on a movable platform with object to camera distance measured. The object was then moved a specified amount to ascertain whether the Kinect’s depth camera would visualize the difference in position of the object. Results: Initial investigations have shown the Kinect depth resolution is dependent on the object to camera distance. Measurements indicate that movements as small as 1 mm can be visualized for objects as close as 50 cm away. This depth resolution decreases linearly with object to camera distance. At 4 m, the depth resolution had decreased to observe a minimum movement of 1 cm. Conclusion: The improved resolution and advanced hardware of the Kinect 2.0 allows for increase of depth resolution over the Kinect 1.0. Although obvious that the depth resolution should decrease with increasing distance from an object given the decrease in number of pixels representing said object, the depth resolution at large distances indicates its usefulness in a clinical setting.« less

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

Pablant, N. A.; Delgado-Aparicio, L.; Bitter, M.

A new energy resolving x-ray pinhole camera has been recently installed on Alcator C-Mod. This diagnostic is capable of 1D or 2D imaging with a spatial resolution of Almost-Equal-To 1 cm, an energy resolution of Almost-Equal-To 1 keV in the range of 3.5-15 keV and a maximum time resolution of 5 ms. A novel use of a Pilatus 2 hybrid-pixel x-ray detector [P. Kraft et al., J. Synchrotron Rad. 16, 368 (2009)] is employed in which the lower energy threshold of individual pixels is adjusted, allowing regions of a single detector to be sensitive to different x-ray energy ranges. Developmentmore » of this new detector calibration technique was done as a collaboration between PPPL and Dectris Ltd. The calibration procedure is described, and the energy resolution of the detector is characterized. Initial data from this installation on Alcator C-Mod is presented. This diagnostic provides line-integrated measurements of impurity emission which can be used to determine impurity concentrations as well as the electron energy distribution.« less

Novel energy resolving x-ray pinhole camera on Alcator C-Mod.

PubMed

Pablant, N A; Delgado-Aparicio, L; Bitter, M; Brandstetter, S; Eikenberry, E; Ellis, R; Hill, K W; Hofer, P; Schneebeli, M

2012-10-01

A new energy resolving x-ray pinhole camera has been recently installed on Alcator C-Mod. This diagnostic is capable of 1D or 2D imaging with a spatial resolution of ≈1 cm, an energy resolution of ≈1 keV in the range of 3.5-15 keV and a maximum time resolution of 5 ms. A novel use of a Pilatus 2 hybrid-pixel x-ray detector [P. Kraft et al., J. Synchrotron Rad. 16, 368 (2009)] is employed in which the lower energy threshold of individual pixels is adjusted, allowing regions of a single detector to be sensitive to different x-ray energy ranges. Development of this new detector calibration technique was done as a collaboration between PPPL and Dectris Ltd. The calibration procedure is described, and the energy resolution of the detector is characterized. Initial data from this installation on Alcator C-Mod is presented. This diagnostic provides line-integrated measurements of impurity emission which can be used to determine impurity concentrations as well as the electron energy distribution.

A methodology for direct quantification of over-ranging length in helical computed tomography with real-time dosimetry.

PubMed

Tien, Christopher J; Winslow, James F; Hintenlang, David E

2011-01-31

In helical computed tomography (CT), reconstruction information from volumes adjacent to the clinical volume of interest (VOI) is required for proper reconstruction. Previous studies have relied upon either operator console readings or indirect extrapolation of measurements in order to determine the over-ranging length of a scan. This paper presents a methodology for the direct quantification of over-ranging dose contributions using real-time dosimetry. A Siemens SOMATOM Sensation 16 multislice helical CT scanner is used with a novel real-time "point" fiber-optic dosimeter system with 10 ms temporal resolution to measure over-ranging length, which is also expressed in dose-length-product (DLP). Film was used to benchmark the exact length of over-ranging. Over-ranging length varied from 4.38 cm at pitch of 0.5 to 6.72 cm at a pitch of 1.5, which corresponds to DLP of 131 to 202 mGy-cm. The dose-extrapolation method of Van der Molen et al. yielded results within 3%, while the console reading method of Tzedakis et al. yielded consistently larger over-ranging lengths. From film measurements, it was determined that Tzedakis et al. overestimated over-ranging lengths by one-half of beam collimation width. Over-ranging length measured as a function of reconstruction slice thicknesses produced two linear regions similar to previous publications. Over-ranging is quantified with both absolute length and DLP, which contributes about 60 mGy-cm or about 10% of DLP for a routine abdominal scan. This paper presents a direct physical measurement of over-ranging length within 10% of previous methodologies. Current uncertainties are less than 1%, in comparison with 5% in other methodologies. Clinical implantation can be increased by using only one dosimeter if codependence with console readings is acceptable, with an uncertainty of 1.1% This methodology will be applied to different vendors, models, and postprocessing methods--which have been shown to produce over-ranging lengths differing by 125%.

Measuring water level in rivers and lakes from lightweight Unmanned Aerial Vehicles

NASA Astrophysics Data System (ADS)

Bandini, Filippo; Jakobsen, Jakob; Olesen, Daniel; Reyna-Gutierrez, Jose Antonio; Bauer-Gottwein, Peter

2017-05-01

The assessment of hydrologic dynamics in rivers, lakes, reservoirs and wetlands requires measurements of water level, its temporal and spatial derivatives, and the extent and dynamics of open water surfaces. Motivated by the declining number of ground-based measurement stations, research efforts have been devoted to the retrieval of these hydraulic properties from spaceborne platforms in the past few decades. However, due to coarse spatial and temporal resolutions, spaceborne missions have several limitations when assessing the water level of terrestrial surface water bodies and determining complex water dynamics. Unmanned Aerial Vehicles (UAVs) can fill the gap between spaceborne and ground-based observations, and provide high spatial resolution and dense temporal coverage data, in quick turn-around time, using flexible payload design. This study focused on categorizing and testing sensors, which comply with the weight constraint of small UAVs (around 1.5 kg), capable of measuring the range to water surface. Subtracting the measured range from the vertical position retrieved by the onboard Global Navigation Satellite System (GNSS) receiver, we can determine the water level (orthometric height). Three different ranging payloads, which consisted of a radar, a sonar and an in-house developed camera-based laser distance sensor (CLDS), have been evaluated in terms of accuracy, precision, maximum ranging distance and beam divergence. After numerous flights, the relative accuracy of the overall system was estimated. A ranging accuracy better than 0.5% of the range and a maximum ranging distance of 60 m were achieved with the radar. The CLDS showed the lowest beam divergence, which is required to avoid contamination of the signal from interfering surroundings for narrow fields of view. With the GNSS system delivering a relative vertical accuracy better than 3-5 cm, water level can be retrieved with an overall accuracy better than 5-7 cm.

High Resolution Radar for NASA and Space Situational Awareness for Observation and Monitoring

NASA Astrophysics Data System (ADS)

Geldzahler, B.; D'Addario, L.; Ott, M.; Birr, R.; Woods, G.; Miller, M.

2014-09-01

NASA has embarked on a series of demonstrations that will enable the implementation of a high power, high resolution X/Ka-band radar system using a phased array of widely spaced 12m antennas to better track and characterize near Earth objects and orbital debris. This radar system also has applications for cost effective space situational awareness. Ka band can provide 5cm ranging resolution, and, with arrays in the western United States and Australia used in an astrometric mode, ? 10 cm resolution at GEO. Here we report the results of a successful X-band demonstration of coherent uplink arraying with real time compensation for atmospheric phase fluctuations at the Kennedy Space Center (KSC) using a system simplified from work previously undertaken. The X-band system is a prelude to the Ka-band work currently underway. The target satellites were components of the DSCS and WGS systems. KSC was chosen for the demonstration site because [a] of reduced implementation costs, [b] there is a lot of water vapor in the air (not Ka-band friendly), and [c] some of the test satellites have low elevations thereby adding more attenuation and turbulence to the demonstration. When Ka-band coherent uplink arraying is demonstrated to work at KSC, it will work and can be deployed anywhere.

Portable, Battery Operated Capillary Electrophoresis with Optical Isomer Resolution Integrated with Ionization Source for Mass Spectrometry

NASA Astrophysics Data System (ADS)

Moini, Mehdi; Rollman, Christopher M.

2016-03-01

We introduce a battery operated capillary electrophoresis electrospray ionization (CE/ESI) source for mass spectrometry with optical isomer separation capability. The source fits in front of low or high resolution mass spectrometers similar to a nanospray source with about the same weight and size. The source has two high voltage power supplies (±25 kV HVPS) capable of operating in forward or reverse polarity modes and powered by a 12 V rechargeable lithium ion battery with operation time of ~10 h. In ultrafast CE mode, in which short narrow capillaries (≤15 μm i.d., 15-25 cm long) and field gradients ≥1000 V/cm are used, peak widths at the base are <1 s wide. Under these conditions, the source provides high resolution separation, including optical isomer resolution in ~1 min. Using a low resolution mass spectrometer (LTQ Velos) with a scan time of 0.07 s/scan, baseline separation of amino acids and their optical isomers were achieved in ~1 min. Moreover, bovine serum albumin (BSA) was analyzed in ~1 min with 56% coverage using the data-dependent MS/MS. Using a high resolution mass spectrometer (Thermo Orbitrap Elite) with 15,000 resolution, the fastest scan time achieved was 0.15 s, which was adequate for CE-MS analysis when optical isomer separation is not required or when the optical isomers were well separated. Figures of merit including a detection limit of 2 fmol and linear dynamic range of two orders of magnitude were achieved for amino acids.

Interferometric system based on swept source-optical coherence tomography scheme applied to the measurement of distances of industrial interest

NASA Astrophysics Data System (ADS)

Morel, Eneas N.; Russo, Nélida A.; Torga, Jorge R.; Duchowicz, Ricardo

2016-01-01

We used an interferometric technique based on typical optical coherence tomography (OCT) schemes for measuring distances of industrial interest. The system employed as a light source a tunable erbium-doped fiber laser of ˜20-pm bandwidth with a tuning range between 1520 and 1570 nm. It has a sufficiently long coherence length to enable long depth range imaging. A set of fiber Bragg gratings was used as a self-calibration method, which has the advantage of being a passive system that requires no additional electronic devices. The proposed configuration and the coherence length of the laser enlarge the range of maximum distances that can be measured with the common OCT configuration, maintaining a good axial resolution. A measuring range slightly >17 cm was determined. The system performance was evaluated by studying the repeatability and axial resolution of the results when the same optical path difference was measured. Additionally, the thickness of a semitransparent medium was also measured.

Development of a low energy electron spectrometer for SCOPE

NASA Astrophysics Data System (ADS)

Tominaga, Yuu; Saito, Yoshifumi; Yokota, Shoichiro

We are newly developing a low-energy charged particle analyzer for the future satellite mission SCOPE (cross Scale COupling in the Plasma universE). The main purpose of the mission is to understand the cross scale coupling between macroscopic MHD scale phenomena and microscopic ion and electron-scale phenomena. In order to under-stand the dynamics of plasma in small scales, we need to observe the plasma with an analyzer which has high time resolution. For ion-scale phenomena, the time resolution must be as high as ion cyclotron frequency (-10 sec) in Earth's magnetosphere. However, for electron-scale phe-nomena, the time resolution must be as high as electron cyclotron frequency (-1 msec). The GEOTAIL satellite that observes Earth's magnetosphere has the analyzer whose time resolution is 12 sec, so the satellite can observe ion-scale phenomena. However in the SCOPE mission, we will go further to observe electron-scale phenomena. Then we need analyzers that have at least several msec time resolution. Besides, we need to make the analyzer as small as possible for the volume and weight restrictions of the satellite. The diameter of the top-hat analyzer must be smaller than 20 cm. In this study, we are developing an electrostatic analyzer that meets such requirements using numerical simulations. The electrostatic analyzer is a spherical/toroidal top-hat electrostatic analyzer with three nested spherical/toroidal deflectors. Using these deflectors, the analyzer measures charged particles simultaneously in two different energy ranges. Therefore time res-olution of the analyzer can be doubled. With the analyzer, we will measure energies from 10 eV to 22.5 keV. In order to obtain three-dimensional distribution functions of low energy parti-cles, the analyzer must have 4-pi str field of view. Conventional electrostatic analyzers use the spacecraft spin to have 4-pi field of view. So the time resolution of the analyzer depends on the spin frequency of the spacecraft. However, we cannot secure the several msec time resolution by using the spacecraft spin. In the SCOPE mission, we set 8 pairs of two nested electrostatic analyzers on each side of the spacecraft, which enable us to secure 4-pi field of view altogether. Then the time resolution of the analyzer does not depend on the spacecraft spin. Given that the sampling time of the analyzer is 0.5 msec, the time resolution of the analyzer can be 8 msec. In order to secure the time resolution as high as 10 msec, the geometric factor of the analyzer has to be as high as 8*10-3 (cm2 str eV/eV/22.5deg). Higher geometric factor requires bigger instrument. However, we have to reduce the volume and weight of the instrument to set it on the satellite. Under these restrictions, we have realized the analyzer which has the geometric factors of 7.5*10-3 (cm2 str eV/eV/22.5deg) (inner sphere) and 10.0*10-3 (cm2 str eV/eV/22.5deg) (outer sphere) with diameter of 17.4 cm.

FTIR Spectrum of the ν 4Band of DCOOD

NASA Astrophysics Data System (ADS)

Tan, T. L.; Goh, K. L.; Ong, P. P.; Teo, H. H.

1999-06-01

The FTIR spectrum of the ν4band of deuterated formic acid (DCOOD) has been measured with a resolution of 0.004 cm-1in the frequency range of 1120 to 1220 cm-1. A total of 1866 assigned transitions have been analyzed and fitted using a Watson'sA-reduced Hamiltonian in theIrrepresentation to derive rovibrational constants for the upper state (v4= 1) with a standard deviation of 0.00036 cm-1. In the course of the analysis, the constants for the ground state were improved by a simultaneous fit of microwave frequencies and combination differences from the infrared measurements. Due to the relatively unperturbed nature of the band, the constants can be used to accurately calculate the infrared line positions for the whole band. Although the band is a hybrid typeAandB, onlya-type transitions were strong enough to be observed. The band center is at 1170.79980 ± 0.00002 cm-1.

Line positions and intensities of the phosphine (PH 3) Pentad near 4.5μm

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

Malathy Devi, V.; Kleiner, Isabelle; Sams, Robert L.

2014-04-01

In order to improve the spectroscopic database for remote sensing of the giant planets, line positions and intensities are determined for the five bands (2ν 2, ν 2 + ν 4, 2ν 4, ν 1 and ν 3) that comprise the Pentad of PH 3 between 1950 and 2450 cm -1. Knowledge of PH 3 spectral line parameters in this region is important for the exploration of dynamics and chemistry on Saturn, (using existing Cassini/VIMS observations) and future near-IR data of Jupiter from Juno and ESA’s Jupiter Icy Moons Explorer (JUICE). For this study, spectra of pure PH 3 frommore » two Fourier transform spectrometers were obtained: (a) five high-resolution (0.00223 cm -1), high signal-to-noise (~1800) spectra recorded at room temperature (298.2 K) with the Bruker IFS 125HR Fourier transform spectrometer (FTS) at the Pacific Northwest National Laboratory (PNNL), Richland, Washington and (b) four high-resolution (at 0.0115 cm -1 resolution), high signal-to-noise (~700) spectra recorded at room temperature in the region 1800–5200 cm -1 using the McMath-Pierce Fourier transform spectrometer located at the National Solar Observatory (NSO) on Kitt Peak. Individual line parameters above 2150 cm -1 were retrieved by simultaneous multispectrum fittings of all five Bruker spectra, while retrievals with the four Kitt Peak spectra were done in the 1938–2168 cm -1 range spectrum by spectrum and averaged. In all, positions and intensities were obtained for more than 4400 lines. These included 53 A+A- split pairs of transitions (arising due to vibration–rotation interactions (Coriolis-type interaction) between the ν 3 and ν 1 fundamental bands) for K" = 3, 6, and 9. Over 3400 positions and 1750 intensities of these lines were ultimately identified as relatively unblended and modeled up to J = 14 and K = 12 with rms values of 0.00133 cm -1 and 7.7%, respectively. The PH 3 line parameters (observed positions and measured intensities with known quantum assignments) and Hamiltonian constants are reported. Finally, comparisons with other recent studies are discussed.« less

Optimization of the spatial resolution for the GE discovery PET/CT 710 by using NEMA NU 2-2007 standards

NASA Astrophysics Data System (ADS)

Yoon, Hyun Jin; Jeong, Young Jin; Son, Hye Joo; Kang, Do-Young; Hyun, Kyung-Yae; Lee, Min-Kyung

2015-01-01

The spatial resolution in positron emission tomography (PET) is fundamentally limited by the geometry of the detector element, the positron's recombination range with electrons, the acollinearity of the positron, the crystal decoding error, the penetration into the detector ring, and the reconstruction algorithms. In this paper, optimized parameters are suggested to produce high-resolution PET images by using an iterative reconstruction algorithm. A phantom with three point sources structured with three capillary tubes was prepared with an axial extension of less than 1 mm and was filled with 18F-fluorodeoxyglucose (18F-FDG) with concentrations above 200 MBq/cc. The performance measures of all the PET images were acquired according to the National Electrical Manufacturers Association (NEMA) NU 2-2007 standards procedures. The parameters for the iterative reconstruction were adjusted around the values recommended by General Electric GE, and the optimized values of the spatial resolution and the full width at half maximum (FWHM) or the full width at tenth of maximum (FWTM) values were found for the best PET resolution. The axial and the transverse spatial resolutions, according to the filtered back-projection (FBP) at 1 cm off-axis, were 4.81 and 4.48 mm, respectively. The axial and the transaxial spatial resolutions at 10 cm off-axis were 5.63 mm and 5.08 mm, respectively, and the trans-axial resolution at 10 cm was evaluated as the average of the radial and the tangential measurements. The recommended optimized parameters of the spatial resolution according to the NEMA phantom for the number of subsets, the number of iterations, and the Gaussian post-filter are 12, 3, and 3 mm for the iterative reconstruction VUE Point HD without the SharpIR algorithm (HD), and 12, 12, and 5.2 mm with SharpIR (HD.S), respectively, according to the Advantage Workstation Volume Share 5 (AW4.6). The performance measurements for the GE Discovery PET/CT 710 using the NEMA NU 2-2007 standards from our results will be helpful in the quantitative analysis of PET scanner images. The spatial resolution was modified more by using an improved algorithm such as HD.S, than by using HD and FBP. The use of the optimized parameters for iterative reconstructions is strongly recommended for qualitative images from the GE Discovery PET/CT 710 scanner.

The Coriolis Interaction between the ν 9 and ν 7 Fundamental Bands of Methylene Fluoride

NASA Astrophysics Data System (ADS)

Goh, K. L.; Tan, T. L.; Ong, P. P.; Teo, H. H.

2000-06-01

The infrared spectrum of the ν7 and ν9 bands of methylene fluoride-d2 (CD2F2) has been recorded with an unapodized resolution of 0.0024 cm-1 in the frequency range of 940-1030 cm-1 using the Fourier transform technique. A weak b-type Coriolis interaction term was found to couple these two vibrational states with band centers about 42 cm-1 apart. By fitting a total of 1031 infrared transitions of both ν7 and ν9 with a standard deviation of 0.0011 cm-1 using a Watson's A-reduced Hamiltonian in the Ir representation with the inclusion of a b-type Coriolis resonance term, two sets of rovibrational constants for ν7 = 1 and ν9 = 1 states up to sextic order were derived. The ν7 band is C type, while the ν9 band is A type with band centers at 961.8958 ± 0.0005 and 1003.7421 ± 0.0001 cm-1, respectively.

Rovibrational Constants for the ν 6 and 2ν 9 Bands of HCOOD by Fourier Transform Infrared Spectroscopy

NASA Astrophysics Data System (ADS)

Tan, T. L.; Goh, K. L.; Ong, P. P.; Teo, H. H.

1999-11-01

The Fourier transform infrared spectrum of the ν6 and 2ν9 bands of deuterated formic acid (HCOOD) was recorded with an apodized resolution of 0.004 cm-1 in the frequency range of 930-1040 cm-1. These two bands with band centers 40 cm-1 apart were mutually coupled by Coriolis and Fermi interactions. By fitting a total of 1076 infrared transitions of both ν6 and 2ν9 with a standard deviation of 0.00075 cm-1 using a Watson's A-reduced Hamiltonian in the Ir representation with the inclusion of c-type Coriolis and a Fermi-resonance term, two sets of rovibrational constants for v6 = 1, and v9 = 2 states were derived for the first time. Both ν6 and 2ν9 bands are A type with band centers at 972.8520 ± 0.0001 and 1011.6766 ± 0.0001 cm-1, respectively.

CF2 Detection in Radio-Frequency Ar/CHF3 Plasmas by Fourier Transform Infrared Spectroscopy

NASA Technical Reports Server (NTRS)

Kim, J. S.; Rao, M. V. V. S.; Cappelli, M. A.; Sharma, S. P.

1999-01-01

CFx radicals, in particular CF2, are instrumental in anisotropic etching of SiO2. In order to optimize the CFx radical population in a given process environment, it is imperative that we understand their production mechanism. Towards this goal, we have conducted a series of quantitative measurements of CF2 radicals in low pressure RF plasmas similar to those used in SiO2 etching. In this study, we present preliminary results for Ar/CHF3 plasmas operating at pressures ranging from 10-50 mTorr and powers ranging from 100-500 W in the GEC reference cell, modified for inductive (transformer) coupling. Fourier transform infrared (FTIR) spectroscop) is used to observe the absorption features of the CF2 radical in the 1114 cm-1 and 1096 cm-1 spectral regions. The FTIR spectrometer is equipped with a high-sensitivity mercury cadmium telluride (MCT) detector and has afixed resolution of 0.125 cm- 1. The CF2 concentrations are measured for a range of operating pressures and discharge power levels, and are compared to measurements of the relative CF2 concentrations made by mass spectrometry using the method of appearance potential for radical selectivity.

Novel eye-safe line scanning 3D laser-radar

NASA Astrophysics Data System (ADS)

Eberle, B.; Kern, Tobias; Hammer, Marcus; Schwanke, Ullrich; Nowak, Heinrich

2014-10-01

Today, the civil market provides quite a number of different 3D-Sensors covering ranges up to 1 km. Typically these sensors are based on single element detectors which suffer from the drawback of spatial resolution at larger distances. Tasks demanding reliable object classification at long ranges can be fulfilled only by sensors consisting of detector arrays. They ensure sufficient frame rates and high spatial resolution. Worldwide there are many efforts in developing 3D-detectors, based on two-dimensional arrays. This paper presents first results on the performance of a recently developed 3D imaging laser radar sensor, working in the short wave infrared (SWIR) at 1.5 μm. It consists of a novel Cadmium Mercury Telluride (CMT) linear array APD detector with 384x1 elements at a pitch of 25 μm, developed by AIM Infrarot Module GmbH. The APD elements are designed to work in the linear (non-Geiger) mode. Each pixel will provide the time of flight measurement, and, due to the linear detection mode, allowing the detection of three successive echoes. The resolution in depth is 15 cm, the maximum repetition rate is 4 kHz. We discuss various sensor concepts regarding possible applications and their dependence on system parameters like field of view, frame rate, spatial resolution and range of operation.

Analysis of Twenty-Two Performance Properties of Diesel, Gasoline, and Jet Fuels Using a Field-Portable Near-Infrared (NIR) Analyzer.

PubMed

Brouillette, Carl; Smith, Wayne; Shende, Chetan; Gladding, Zack; Farquharson, Stuart; Morris, Robert E; Cramer, Jeffrey A; Schmitigal, Joel

2016-05-01

The change in custody of fuel shipments at depots, pipelines, and ports could benefit from an analyzer that could rapidly verify that properties are within specifications. To meet this need, the design requirements for a fuel analyzer based on near-infrared (NIR) spectroscopy, such as spectral region and resolution, were examined. It was found that the 1000 to 1600 nm region, containing the second CH overtone and combination vibrational modes of hydrocarbons, provided the best near-infrared to fuel property correlations when path length was taken into account, whereas 4 cm(-1) resolution provided only a modest improvement compared to 16 cm(-1) resolution when four or more latent variables were used. Based on these results, a field-portable near-infrared fuel analyzer was built that employed an incandescent light source, sample compartment optics to hold 2 mL glass sample vials with ∼1 cm path length, a transmission grating, and a 256 channel InGaAs detector that measured the above stated wavelength range with 5-6 nm (∼32 cm(-1)) resolution. The analyzer produced high signal-to-noise ratio (SNR) spectra of samples in 5 s. Twenty-two property correlation models were developed for diesel, gasoline, and jet fuels with root mean squared error of correlation - cross-validated values that compared favorably to corresponding ASTM reproducibility values. The standard deviations of predicted properties for repeat measurements at 4, 24, and 38℃ were often better than ASTM documented repeatability values. The analyzer and diesel property models were tested by measuring seven diesel samples at a local ASTM certification laboratory. The standard deviations between the analyzer determined values and the ASTM measured values for these samples were generally better than the model root mean squared error of correlation-cross-validated values for each property. © The Author(s) 2016.

Solar Flare Physics

NASA Technical Reports Server (NTRS)

Schmahl, Edward J.; Kundu, Mukul R.

2000-01-01

During the past year we have been working with the HESSI (High Energy Solar Spectroscopic Imager) team in preparation for launch in early 2001. HESSI has as its primary scientific goal photometric imaging and spectroscopy of solar flares in hard X-rays and gamma-rays with an approx. 2 sec angular resolution, approx. keV energy resolution and approx. 2 s time resolution over the 6 keV to 15 MeV energy range. We have performed tests of the imager using a specially designed experiment which exploits the second-harmonic response of HESSI's sub-collimators to an artificial X-ray source at a distance of 1550 cm from its front grids. Figures show the response to X-rays at energies in the range where HESSI is expected to image solar flares. To prepare the team and the solar user community for imaging flares with HESSI, we have written a description of the major imaging concepts. This paper will be submitted for publication in a referred journal.

A preliminary measurement of the cosmic microwave background spectrum by the Cosmic Background Explorer (COBE) satellite

NASA Technical Reports Server (NTRS)

Mather, J. C.; Cheng, E. S.; Shafer, R. A.; Bennett, C. L.; Boggess, N. W.; Dwek, E.; Hauser, M. G.; Kelsall, T.; Moseley, S. H., Jr.; Silverberg, R. F.

1990-01-01

A preliminary spectrum is presented of the background radiation between 1 and 20/cm from regions near the north Galactic pole, as observed by the FIRAS instrument on the COBE satellite. The spectral resolution is 1/cm. The spectrum is well fitted by a blackbody with a temperature of 2.735 + or - 0.06 K, and the deviation from a blackbody is less than 1 percent of the peak intensity over the range 1-20/cm. These new data show no evidence for the submillimeter excess previously reported by Matsumoto et al. (1988) in the cosmic microwave background. Further analysis and additional data are expected to improve the sensitivity to deviations from a blackbody spectrum by an order of magnitude.

Cris-atms Retrievals Using an AIRS Science Team Version 6-like Retrieval Algorithm

NASA Technical Reports Server (NTRS)

Susskind, Joel; Kouvaris, Louis C.; Iredell, Lena

2014-01-01

CrIS is the infrared high spectral resolution atmospheric sounder launched on Suomi-NPP in 2011. CrISATMS comprise the IRMW Sounding Suite on Suomi-NPP. CrIS is functionally equivalent to AIRS, the high spectral resolution IR sounder launched on EOS Aqua in 2002 and ATMS is functionally equivalent to AMSU on EOS Aqua. CrIS is an interferometer and AIRS is a grating spectrometer. Spectral coverage, spectral resolution, and channel noise of CrIS is similar to AIRS. CrIS spectral sampling is roughly twice as coarse as AIRSAIRS has 2378 channels between 650 cm-1 and 2665 cm-1. CrIS has 1305 channels between 650 cm-1 and 2550 cm-1. Spatial resolution of CrIS is comparable to AIRS.

Impact of detector design on imaging performance of a long axial field-of-view, whole-body PET scanner

NASA Astrophysics Data System (ADS)

Surti, S.; Karp, J. S.

2015-07-01

Current generation of commercial time-of-flight (TOF) PET scanners utilize 20-25 mm thick LSO or LYSO crystals and have an axial FOV (AFOV) in the range of 16-22 mm. Longer AFOV scanners would provide increased intrinsic sensitivity and require fewer bed positions for whole-body imaging. Recent simulation work has investigated the sensitivity gains that can be achieved with these long AFOV scanners, and has motivated new areas of investigation such as imaging with a very low dose of injected activity as well as providing whole-body dynamic imaging capability in one bed position. In this simulation work we model a 72 cm long scanner and prioritize the detector design choices in terms of timing resolution, crystal size (spatial resolution), crystal thickness (detector sensitivity), and depth-of-interaction (DOI) measurement capability. The generated list data are reconstructed with a list-mode OSEM algorithm using a Gaussian TOF kernel that depends on the timing resolution and blob basis functions for regularization. We use lesion phantoms and clinically relevant metrics for lesion detectability and contrast measurement. The scan time was fixed at 10 min for imaging a 100 cm long object assuming a 50% overlap between adjacent bed positions. Results show that a 72 cm long scanner can provide a factor of ten reduction in injected activity compared to an identical 18 cm long scanner to get equivalent lesion detectability. While improved timing resolution leads to further gains, using 3 mm (as opposed to 4 mm) wide crystals does not show any significant benefits for lesion detectability. A detector providing 2-level DOI information with equal crystal thickness also does not show significant gains. Finally, a 15 mm thick crystal leads to lower lesion detectability than a 20 mm thick crystal when keeping all other detector parameters (crystal width, timing resolution, and DOI capability) the same. However, improved timing performance with 15 mm thick crystals can provide similar or better performance than that achieved by a detector using 20 mm thick crystals.

Evaluation of airborne image data for mapping riparian vegetation within the Grand Canyon

USGS Publications Warehouse

Davis, Philip A.; Staid, Matthew I.; Plescia, Jeffrey B.; Johnson, Jeffrey R.

2002-01-01

This study examined various types of remote-sensing data that have been acquired during a 12-month period over a portion of the Colorado River corridor to determine the type of data and conditions for data acquisition that provide the optimum classification results for mapping riparian vegetation. Issues related to vegetation mapping included time of year, number and positions of wavelength bands, and spatial resolution for data acquisition to produce accurate vegetation maps versus cost of data. Image data considered in the study consisted of scanned color-infrared (CIR) film, digital CIR, and digital multispectral data, whose resolutions from 11 cm (photographic film) to 100 cm (multispectral), that were acquired during the Spring, Summer, and Fall seasons in 2000 for five long-term monitoring sites containing riparian vegetation. Results show that digitally acquired data produce higher and more consistent classification accuracies for mapping vegetation units than do film products. The highest accuracies were obtained from nine-band multispectral data; however, a four-band subset of these data, that did not include short-wave infrared bands, produced comparable mapping results. The four-band subset consisted of the wavelength bands 0.52-0.59 µm, 0.59-0.62 µm, 0.67-0.72 µm, and 0.73-0.85 µm. Use of only three of these bands that simulate digital CIR sensors produced accuracies for several vegetation units that were 10% lower than those obtained using the full multispectral data set. Classification tests using band ratios produced lower accuracies than those using band reflectance for scanned film data; a result attributed to the relatively poor radiometric fidelity maintained by the film scanning process, whereas calibrated multispectral data produced similar classification accuracies using band reflectance and band ratios. This suggests that the intrinsic band reflectance of the vegetation is more important than inter-band reflectance differences in attaining high mapping accuracies. These results also indicate that radiometrically calibrated sensors that record a wide range of radiance produce superior results and that such sensors should be used for monitoring purposes. When texture (spatial variance) at near-infrared wavelength is combined with spectral data in classification, accuracy increased most markedly (20-30%) for the highest resolution (11-cm) CIR film data, but decreased in its effect on accuracy in lower-resolution multi-spectral image data; a result observed in previous studies (Franklin and McDermid 1993, Franklin et al. 2000, 2001). While many classification unit accuracies obtained from the 11-cm film CIR band with texture data were in fact higher than those produced using the 100-cm, nine-band multispectral data with texture, the 11-cm film CIR data produced much lower accuracies than the 100-cm multispectral data for the more sparsely populated vegetation units due to saturation of picture elements during the film scanning process in vegetation units with a high proportion of alluvium. Overall classification accuracies obtained from spectral band and texture data range from 36% to 78% for all databases considered, from 57% to 71% for the 11-cm film CIR data, and from 54% to 78% for the 100-cm multispectral data. Classification results obtained from 20-cm film CIR band and texture data, which were produced by applying a Gaussian filter to the 11-cm film CIR data, showed increases in accuracy due to texture that were similar to those observed using the original 11-cm film CIR data. This suggests that data can be collected at the lower resolution and still retain the added power of vegetation texture. Classification accuracies for the riparian vegetation units examined in this study do not appear to be influenced by season of data acquisition, although data acquired under direct sunlight produced higher overall accuracies than data acquired under overcast conditions. The latter observation, in addition to the importance of band reflectance for classification, implies that data should be acquired near summer solstice when sun elevation and reflectance is highest and when shadows cast by steep canyon walls are minimized.

A Submillimeter Resolution PET Prototype Evaluated With an 18F Inkjet Printed Phantom

NASA Astrophysics Data System (ADS)

Schneider, Florian R.; Hohberg, Melanie; Mann, Alexander B.; Paul, Stephan; Ziegler, Sibylle I.

2015-10-01

This work presents a submillimeter resolution PET (Positron Emission Tomography) scanner prototype based on SiPM/MPPC arrays (Silicon Photomultiplier/Multi Pixel Photon Counter). Onto each active area a 1 ×1 ×20 mm3 LYSO (Lutetium-Yttrium-Oxyorthosilicate) scintillator crystal is coupled one-to-one. Two detector modules facing each other in a distance of 10.0 cm have been set up with in total 64 channels that are digitized by SADCs (Sampling Analog to Digital Converters) with 80 MHz, 10 bit resolution and FPGA (Field Programmable Gate Array) based extraction of energy and time information. Since standard phantoms are not sufficient for testing submillimeter resolution at which positron range is an issue, a 18F inkjet printed phantom has been used to explore the limit in spatial resolution. The phantom could be successfully reconstructed with an iterative MLEM (Maximum Likelihood Expectation Maximization) and an analytically calculated system matrix based on the DRF (Detector Response Function) model. The system yields a coincidence time resolution of 4.8 ns FWHM, an energy resolution of 20%-30% FWHM and a spatial resolution of 0.8 mm.

Predicting spatial variations of tree species richness in tropical forests from high-resolution remote sensing.

PubMed

Fricker, Geoffrey A; Wolf, Jeffrey A; Saatchi, Sassan S; Gillespie, Thomas W

2015-10-01

There is an increasing interest in identifying theories, empirical data sets, and remote-sensing metrics that can quantify tropical forest alpha diversity at a landscape scale. Quantifying patterns of tree species richness in the field is time consuming, especially in regions with over 100 tree species/ha. We examine species richness in a 50-ha plot in Barro Colorado Island in Panama and test if biophysical measurements of canopy reflectance from high-resolution satellite imagery and detailed vertical forest structure and topography from light detection and ranging (lidar) are associated with species richness across four tree size classes (>1, 1-10, >10, and >20 cm dbh) and three spatial scales (1, 0.25, and 0.04 ha). We use the 2010 tree inventory, including 204,757 individuals belonging to 301 species of freestanding woody plants or 166 ± 1.5 species/ha (mean ± SE), to compare with remote-sensing data. All remote-sensing metrics became less correlated with species richness as spatial resolution decreased from 1.0 ha to 0.04 ha and tree size increased from 1 cm to 20 cm dbh. When all stems with dbh > 1 cm in 1-ha plots were compared to remote-sensing metrics, standard deviation in canopy reflectance explained 13% of the variance in species richness. The standard deviations of canopy height and the topographic wetness index (TWI) derived from lidar were the best metrics to explain the spatial variance in species richness (15% and 24%, respectively). Using multiple regression models, we made predictions of species richness across Barro Colorado Island (BCI) at the 1-ha spatial scale for different tree size classes. We predicted variation in tree species richness among all plants (adjusted r² = 0.35) and trees with dbh > 10 cm (adjusted r² = 0.25). However, the best model results were for understory trees and shrubs (dbh 1-10 cm) (adjusted r² = 0.52) that comprise the majority of species richness in tropical forests. Our results indicate that high-resolution remote sensing can predict a large percentage of variance in species richness and potentially provide a framework to map and predict alpha diversity among trees in diverse tropical forests.

The energy balance and pressure in the solar transition zone for network and active region features

NASA Technical Reports Server (NTRS)

Nicolas, K. R.; Bartoe, J.-D. F.; Brueckner, G. E.; Vanhoosier, M. E.

1979-01-01

The electron pressure and energy balance in the solar transition zone are determined for about 125 network and active region features on the basis of high spectral and spatial resolution extreme ultraviolet spectra. Si III line intensity ratios obtained from the Naval Research Laboratory high-resolution telescope and spectrograph during a rocket flight are used as diagnostics of electron density and pressure for solar features near 3.5 x 10 to the 4th K. Observed ratios are compared with the calculated dependence of the 1301 A/1312 A and 1301 A/1296 A line intensity ratios on electron density, temperature and pressure. Electron densities ranging from 2 x 10 to the 10th/cu cm to 10 to the 12th/cu cm and active region pressures from 3 x 10 to the 15th to 10 to the 16th/cu cm K are obtained. Energy balance calculations reveal the balance of the divergence of the conductive flux and turbulent energy dissipation by radiative energy losses in a plane-parallel homogeneous transition zone (fill factor of 1), and an energy source requirement for a cylindrical zone geometry (fill factor less than 0.04).

High-resolution deployable telescope for satellite applications

NASA Astrophysics Data System (ADS)

Pica, Giulia; Ciofaniello, Luca; Mattei, Stefania; Santovito, Maria Rosaria; Gardi, Roberto

2004-02-01

CO.RI.S.T.A. is involved in a research project funded by ASI (Italian Space Agency), named MITAR, to realise a very compact, lightweight deployable telescope in visible wavelength range to get earth images from microsatellite. The satellite considered for the study is SMART, an Italian academic multi-mission microsatellite operating on circular sun-synchronous orbits. The telescope has a Cassegrain configuration with a parabolic primary mirror and an hyperbolic secondary mirror. This configuration guaranties the best aberrations corrections and the best compactness. The primary and the secondary mirror are 40 cm and 10 cm in diameter respectively, while their relative distance is 52cm. Mirrors will be realised with innovative composite material to obtain lightweight optical elements. Thanks to its limited size and light weight, the system can be easily deployed. The deployable structure will keep the secondary mirror close to the primary one during launch phases. Once in orbit, a system of lenticular tape springs and dumpers will extend the structure. The structure will be enclosed in multilayer blankets that will shield the sensor from light and will thermally stabilize the structure, preventing excessive thermal deformation. The images will be detected by a very high resolution CCD camera installed onboard the satellite.

High-resolution well-log derived dielectric properties of gas-hydrate-bearing sediments, Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

USGS Publications Warehouse

Sun, Y.; Goldberg, D.; Collett, T.; Hunter, R.

2011-01-01

A dielectric logging tool, electromagnetic propagation tool (EPT), was deployed in 2007 in the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well (Mount Elbert Well), North Slope, Alaska. The measured dielectric properties in the Mount Elbert well, combined with density log measurements, result in a vertical high-resolution (cm-scale) estimate of gas hydrate saturation. Two hydrate-bearing sand reservoirs about 20 m thick were identified using the EPT log and exhibited gas-hydrate saturation estimates ranging from 45% to 85%. In hydrate-bearing zones where variation of hole size and oil-based mud invasion are minimal, EPT-based gas hydrate saturation estimates on average agree well with lower vertical resolution estimates from the nuclear magnetic resonance logs; however, saturation and porosity estimates based on EPT logs are not reliable in intervals with substantial variations in borehole diameter and oil-based invasion.EPT log interpretation reveals many thin-bedded layers at various depths, both above and below the thick continuous hydrate occurrences, which range from 30-cm to about 1-m thick. Such thin layers are not indicated in other well logs, or from the visual observation of core, with the exception of the image log recorded by the oil-base microimager. We also observe that EPT dielectric measurements can be used to accurately detect fine-scale changes in lithology and pore fluid properties of hydrate-bearing sediments where variation of hole size is minimal. EPT measurements may thus provide high-resolution in-situ hydrate saturation estimates for comparison and calibration with laboratory analysis. ?? 2010 Elsevier Ltd.

Infrared spectrometry of Venus: IR Fourier spectrometer on Venera 15 as a precursor of PFS for Venus express

NASA Astrophysics Data System (ADS)

Zasova, L. V.; Moroz, V. I.; Formisano, V.; Ignatiev, N. I.; Khatuntsev, I. V.

2004-01-01

Thermal infrared spectrometry in the range 6-40 μm with spectral resolution of 4.5-6.5 cm -1 was realized onboard of Venera 15 for the middle atmosphere of Venus investigations. The 3-D temperature and zonal wind fields ( h, ϕ, LT) in the range 55-100 km and the 3-D aerosol field ( h, ϕ, LT) in the range 55-70 km were retrieved and analyzed. The solar related waves at isobaric levels, generated by the absorbed solar energy, were investigated. In the thermal IR spectral range the, ν1, ν2 and ν3 SO 2 and the H 2O rotational (40 μm) and vibro-rotational (6.3 μm) absorption bands are observed and used for minor compounds retrieval. An advantage of the thermal infrared spectrometry method is that both the temperature and aerosol profiles, which need for retrieval of the vertical profiles of minor compounds, are evaluated from the same spectrum. The Fourier spectrometer on Venera-15 may be considered as a precursor of the Planetary Fourier Spectrometer (PI Prof. V. Formisano), which is included in the payload of the planned Venus Express mission. It has a spectral range 0.9-45 μm, separated into two channels: a short wavelength channel (SWC) in the range 0.9-5 μm and a long wavelength channel (LWC) from 6 to 45 μm, and spectral resolution of 1-2 cm -1. In the history of planetary Fourier spectrometry the PFS is a unique instrument, which possesses a short wavelength channel. A functioning of this instrument on the polar orbit with a good spatial and local time coverage will advance our knowledge in the fundamental problems of the Venus atmosphere.

Determining the Parameters of the Effective Rovibrational Hamiltonian of the ν7+ν8 Band of the Ethylene-1-13C Molecule

NASA Astrophysics Data System (ADS)

Aslapovskaya, Yu. S.

2018-06-01

The spectrum of the ν7 + ν8 band of the ethylene-1-13C (13C12CH4) molecule is recorded with a Bruker IFS 125 HR Fourier spectrometer in the range from 1500 to 2100 cm-1 with a resolution of 0.0025 cm-1. As a result of analysis of the experimental spectrum, more than 1000 transitions belonging to the ν7 + ν8 band are assigned. Parameters of the Hamiltonian obtained as a result of solving the inverse spectroscopic problem reproduce 400 initial experimental energies with error close to the experimental one.

Variable Temperature Performance of a Si(Li) Detector Stack

NASA Technical Reports Server (NTRS)

Hubbard, G. Scott; McMurray, Robert E., Jr.; Keller, R. G.; Wercinski, P. F.; Walton, J. T.; Wong, Y. K.

1994-01-01

New experimental data is presented which displays 137Cs resolution of both single Si(Li) devices and a detector stack 2 cm in height as a function of temperature (85 K greater than or equal to T greater than or equal to 245 K). We also discuss variations in photopeak shape which indicate that detector charge collection may be temperature dependent over the range of interest.

SU-C-207A-02: Proton Radiography Using Pencil Beam Scanning and a Novel, Low-Cost Range Telescope

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

Dolney, D; Mayers, G; Newcomer, M

Purpose: While the energy of therapeutic proton beams can be adjusted to penetrate to any given depth in water, range uncertainties arise in patients due in part to imprecise knowledge of the stopping power of protons in human tissues [1]. Proton radiography is one approach to reduce the beam range uncertainty [2], thereby allowing for a reduction in treatment margins and dose escalation. Methods: The authors have adapted a novel detector technology based on Micromesh Gaseous Structure (“Micromegas”) for proton therapy beams and have demonstrated fine spatial and time resolution of magnetically scanned proton pencil beams, as well as widemore » dynamic range for dosimetry [3]. The authors have constructed a prototype imaging system comprised of 5 Micromegas layers. Proton radiographs were obtained downstream of solid water assemblies. The position-sensitive monitor chambers in the IBA proton delivery nozzle provide the beam entrance position. Results: Our technique achieves spatial resolution as low as 300 µm and water-equivalent thickness (WET) resolution as good as 0.02% (60 µm out of 31 cm total thickness). The dose delivered to the patient is kept below 2 cGy. The spatial resolution as a function of sample rate and number of delivered protons is found to be near the theoretical Cramer-Rao lower bound. By extrapolating the CR bound, we argue that the imaging dose could be further lowered to 1 mGy, while still achieving submillimeter spatial resolution, by achievable instrumentation and beam delivery modifications. Conclusion: For proton radiography, high spatial and WET resolution can be achieved, with minimal additional dose to patient, by using magnetically scanned proton pencil beams and Micromegas detectors.« less

Annealing studies of heteroepitaxial InSbN on GaAs grown by molecular beam epitaxy for long-wavelength infrared detectors

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

Patra, Nimai C.; Bharatan, Sudhakar; Li Jia

2012-10-15

We report the effect of annealing on the structural, vibrational, electrical, and optical properties of heteropepitaxially grown InSbN epilayers on GaAs substrate by molecular beam epitaxy for long-wavelength infrared detector applications. As-grown epilayers exhibited high N incorporation in the both substitutional and interstitial sites, with N induced defects as evidenced from high resolution x-ray diffraction, secondary ion mass spectroscopy, and room temperature (RT) micro-Raman studies. The as-grown optical band gap was observed at 0.132 eV ({approx}9.4 {mu}m) and the epilayer exhibited high background carrier concentration at {approx}10{sup 18} cm{sup -3} range with corresponding mobility of {approx}10{sup 3} cm{sup 2}/Vs. Exmore » situ and in situ annealing at 430 Degree-Sign C though led to the loss of N but improved InSb quality due to effective annihilation of N related defects and other lattice defects attested to enhanced InSb LO phonon modes in the corresponding Raman spectra. Further, annealing resulted in the optical absorption edge red shifting to 0.12 eV ({approx}10.3 {mu}m) and the layers were characterized by reduced background carrier concentration in the {approx}10{sup 16} cm{sup -3} range with enhanced mobility in {approx}10{sup 4} cm{sup 2}/Vs range.« less

Analysis of Moisture Content in Beetroot using Fourier Transform Infrared Spectroscopy and by Principal Component Analysis.

PubMed

Nesakumar, Noel; Baskar, Chanthini; Kesavan, Srinivasan; Rayappan, John Bosco Balaguru; Alwarappan, Subbiah

2018-05-22

The moisture content of beetroot varies during long-term cold storage. In this work, we propose a strategy to identify the moisture content and age of beetroot using principal component analysis coupled Fourier transform infrared spectroscopy (FTIR). Frequent FTIR measurements were recorded directly from the beetroot sample surface over a period of 34 days for analysing its moisture content employing attenuated total reflectance in the spectral ranges of 2614-4000 and 1465-1853 cm -1 with a spectral resolution of 8 cm -1 . In order to estimate the transmittance peak height (T p ) and area under the transmittance curve [Formula: see text] over the spectral ranges of 2614-4000 and 1465-1853 cm -1 , Gaussian curve fitting algorithm was performed on FTIR data. Principal component and nonlinear regression analyses were utilized for FTIR data analysis. Score plot over the ranges of 2614-4000 and 1465-1853 cm -1 allowed beetroot quality discrimination. Beetroot quality predictive models were developed by employing biphasic dose response function. Validation experiment results confirmed that the accuracy of the beetroot quality predictive model reached 97.5%. This research work proves that FTIR spectroscopy in combination with principal component analysis and beetroot quality predictive models could serve as an effective tool for discriminating moisture content in fresh, half and completely spoiled stages of beetroot samples and for providing status alerts.

Error Analysis of CM Data Products Sources of Uncertainty

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

Hunt, Brian D.; Eckert-Gallup, Aubrey Celia; Cochran, Lainy Dromgoole

This goal of this project is to address the current inability to assess the overall error and uncertainty of data products developed and distributed by DOE’s Consequence Management (CM) Program. This is a widely recognized shortfall, the resolution of which would provide a great deal of value and defensibility to the analysis results, data products, and the decision making process that follows this work. A global approach to this problem is necessary because multiple sources of error and uncertainty contribute to the ultimate production of CM data products. Therefore, this project will require collaboration with subject matter experts across amore » wide range of FRMAC skill sets in order to quantify the types of uncertainty that each area of the CM process might contain and to understand how variations in these uncertainty sources contribute to the aggregated uncertainty present in CM data products. The ultimate goal of this project is to quantify the confidence level of CM products to ensure that appropriate public and worker protections decisions are supported by defensible analysis.« less

Analysis of the Coriolis Interaction between ν 6 and ν 8 Bands of HCOOH

NASA Astrophysics Data System (ADS)

Tan, T. L.; Goh, K. L.; Ong, P. P.; Teo, H. H.

2000-08-01

The Fourier transform infrared (FTIR) spectrum of the ν6 band of formic acid (HCOOH) has been recorded with a resolution of 0.0024 cm-1 in the spectral range 1050-1160 cm-1. The ν6 band was found to be strongly perturbed by the nearby ν8 band centered at about 1033.5 cm-1. Using a Watson's A-reduced Hamiltonian in the Ir representation, and with the inclusion of a-type Coriolis coupling constant, a simultaneous fit of ν6 and ν8 was performed. A total of 2485 infrared transitions including about 700 perturbed transitions of ν6 and 19 transitions of ν8 was fitted with an rms uncertainty of 0.0006 cm-1. Accurate rovibrational constants up to sextic order for both ν6 and ν8 were obtained. The ν6 band was analyzed to be a type AB hybrid with a band center at 1104.852109 ± 0.000050 cm-1. The band center for ν8 was found to be 1033.4647 ± 0.0021 cm-1.

Climate Impact on South America due to Land Use Degradation of Amazon Rainforest during Winter and Summer Periods by RegCM3 Model

NASA Astrophysics Data System (ADS)

Silva, M. E. S.; Da Rocha, R.; Pereira, G.

2015-12-01

In this study we investigated the climatic impact over South America region due to the increasing of deforestation at the eastern and southern regions of Amazon through the use of the climate model RegCM3 with 50 km of spatial resolution. Many studies, among global and regional models have been used to simulate climatic impact due to deforestation. Most of them used relatively coarse resolution, small domains over South America, besides do not consider deforestation as usually observed. In order to verify the RegCM3 ability to simulate climate impacts due to Amazon deforestation including relatively higher horizontal resolutions, 50 km, a larger domain, the whole South America, deforested areas more similar to the route-shaped commonly seen, and a landuse updating, the model was run for the 2001-2006 period. As the major part of the previous studies focusing Amazon deforestation, RegCM3-50km simulated over degraded areas air temperature increase, ranging from 1.0 to 2.5oC, and precipitation decreasing, ~10%. These aspects are mainly resulting from soil water depletion and roughness vegetation decreasing, both inhibiting evapotranspiration processes. Apart from these results, the model with 50 km simulated precipitation increasing, ~10%, over the eastern South America and adjacent South Atlantic ocean, after Amazon deforestation. Seeking for physical related reasons able to provide the precipitation increasing during rainy seasons, over eastern South America, we found out that upper levels high pressure system (the Bolivian High) intensification, coupled to the southeastward trough, what follows the low troposphere warming, seems to contribute to the precipitation increasing. The climatic impact simulated for winter seasons presents strongest values for areas with altered landuse, over the north region of South America.

Fusion and Visualization of HiRISE Super-Resolution, Shape-from-Shading DTM with MER Stereo 3D Reconstructions

NASA Astrophysics Data System (ADS)

Gupta, S.; Paar, G.; Muller, J. P.; Tao, Y.; Tyler, L.; Traxler, C.; Hesina, G.; Huber, B.; Nauschnegg, B.

2014-12-01

The FP7-SPACE project PRoViDE has assembled a major portion of the imaging data gathered so far from rover vehicles, landers and probes on extra-terrestrial planetary surfaces into a unique database, bringing them into a common planetary geospatial context and providing access to a complete set of 3D vision products. One major aim of PRoViDE is the fusion between orbiter and rover image products. To close the gap between HiRISE imaging resolution (down to 25cm for the OrthoRectified image (ORI), down to 1m for the DTM) and surface vision products, images from multiple HiRISE acquisitions are combined into a super resolution data set (Tao & Muller, 2014), increasing to 5cm resolution the Ortho images. Furthermore, shape-from-shading is applied to one of the ORIs at its original resolution for refinement of the HiRISE DTM, leading to DTM ground resolutions of up to 25 cm. After texture-based co-registration with these refined orbiter 3D products, MER PanCam and NavCam 3D image products can be smoothly pasted into a multi-resolution 3D data representation. Typical results from the MER mission are presented by a dedicated real-time rendering tool which is fed by a hierarchical 3D data structure that is able to cope with all involved scales from global planetary scale down to close-up reconstructions in the mm range. This allows us to explore and analyze the geological characteristics of rock outcrops, for example the detailed geometry and internal features of sedimentary rock layers, to aid paleoenvironmental interpretation. This integrated approach enables more efficient development of geological models of martian rock outcrops. The rendering tool also provides measurement tools to obtain geospatial data of surface points and distances between them. We report on novel scientific use cases and the added value potential of the resultant high-quality data set and presentation means to support further geologic investigations. The research leading to these results has received funding from the EC's 7th Framework Programme (FP7/2007-2013) under grant agreement n° 312377.

Research on the underwater target imaging based on the streak tube laser lidar

NASA Astrophysics Data System (ADS)

Cui, Zihao; Tian, Zhaoshuo; Zhang, Yanchao; Bi, Zongjie; Yang, Gang; Gu, Erdan

2018-03-01

A high frame rate streak tube imaging lidar (STIL) for real-time 3D imaging of underwater targets is presented in this paper. The system uses 532nm pulse laser as the light source, the maximum repetition rate is 120Hz, and the pulse width is 8ns. LabVIEW platform is used in the system, the system control, synchronous image acquisition, 3D data processing and display are realized through PC. 3D imaging experiment of underwater target is carried out in a flume with attenuation coefficient of 0.2, and the images of different depth and different material targets are obtained, the imaging frame rate is 100Hz, and the maximum detection depth is 31m. For an underwater target with a distance of 22m, the high resolution 3D image real-time acquisition is realized with range resolution of 1cm and space resolution of 0.3cm, the spatial relationship of the targets can be clearly identified by the image. The experimental results show that STIL has a good application prospect in underwater terrain detection, underwater search and rescue, and other fields.

High resolution analysis of the FTIR spectra of trifluoroamine NF3

NASA Astrophysics Data System (ADS)

Bolotova, I. B.; Ulenikov, O. N.; Bekhtereva, E. S.; Albert, S.; Bauerecker, S.; Hollenstein, H.; Lerch, Ph.; Quack, M.; Peter, T.; Seyfang, G.; Wokaun, A.

2018-06-01

We report high resolution Fourier Transform Infrared (FTIR) spectra of nitrogen trifluoride (trifluoroamine, NF3) measured with the Zürich Bruker prototype spectrometer (ZP 2001) and the SLS THz/FTIR setup (2009 prototype) in the range 20-3000 cm-1 at temperatures between 80 and 120 K using a collisional cooling cell designed with White cell multipath reflection optics and at room temperature (296 K). Except in the far-infrared with instrument limited resolution (Δν˜FWHM = 0.0008 cm-1) many of the spectra are nearly Doppler limited. Rovibrational transitions were assigned to 13 different vibrational bands and were used then in the fitting procedure. We re-investigated the bands 2ν4,ν1,ν2 +ν4,ν1 +ν4 , 2ν3 and ν1 +ν3 , which had been studied before, and we have analyzed the ν2 +ν3 , 2ν1,ν1 +ν2 +ν4,ν1 +ν2 +ν3,ν2 + 2ν3, 3ν3,ν1 + 2ν3 bands for the first time. All our analyses refer to the isotopomer 14 NF3.

Ka Band Objects: Observation and Monitoring (KaBOOM)

NASA Astrophysics Data System (ADS)

Geldzahler, B.

2012-09-01

NASA has embarked on a path that will enable the implementation of a high power, high resolution X/Ka band radar system using widely spaced 12m antennas to better track and characterize near Earth objects and orbital debris. This radar system also has applications for cost effective space situational awareness. We shall demonstrate Ka band coherent uplink arraying with real-time atmospheric compensation using three 12m antennas at the Kennedy Space Center (KSC). Our proposed radar system can complement and supplement the activities of the Space Fence. The proposed radar array has the advantages of filling the gap between dusk and dawn and offers the possibility of high range resolution (4 cm) and high spatial resolution (?10 cm at GEO) when used in a VLBI mode. KSC was chosen because [a] of reduced implementation costs, [b] there is a lot of water vapor in the air (not Ka band friendly), and [c] the test satellites have a low elevation adding more attenuation and turbulence to the demonstration. If Ka band coherent uplink arraying can be made to work at KSC, it will work anywhere. We expect to rebaseline X-band in 2013, and demonstrate Ka band uplink arraying in 2014.

Exploring growth conditions and Eu2+ concentration effects for KSr2I5:Eu scintillator crystals II: Ø 25 mm crystals

NASA Astrophysics Data System (ADS)

Stand, L.; Zhuravleva, M.; Johnson, J.; Koschan, M.; Wu, Y.; Donnald, S.; Vaigneur, K.; Lukosi, E.; Melcher, C. L.

2018-02-01

Europium doped potassium strontium iodide is a very promising scintillator for national security applications due to its ease of growth and excellent scintillation properties. For this work the fast crystal growth and scintillation properties of 1-inch diameter single crystals of KSr2I5:Eu2+ (KSI:Eu) were investigated. We focused our efforts on optimizing the growth parameters required to produce one-inch diameter crystals without decreasing the previously reported fast pulling rate of 5 mm/h. Cracking was minimized by replacing the quartz ampoules with carbon coated quartz ampoules; thus, several crack free single crystals of KSI with varying Eu2+ concentrations were grown, including a Ø 1″ by 6″ long boule with 2.5% Eu. The maximum achievable performance of each crystal was measured using small 0.012 cm3 specimens. The volumetric dependencies of the light yield, energy resolution and decay time were evaluated using KSI:Eu 2% specimens with volumes ranging from 0.012 cm3 to 18 cm3. For large volumes (≥ 9 cm3), the performance was comparable to other high performing scintillators, with light yields up to 78,200 ph/MeV and energy resolutions as good as 3.2% at 662 keV. The initial version of a hermetic package has been developed, and the stability of the sealed crystal is promising.

Preliminary evaluation of a novel energy-resolved photon-counting gamma ray detector.

PubMed

Meng, L-J; Tan, J W; Spartiotis, K; Schulman, T

2009-06-11

In this paper, we present the design and preliminary performance evaluation of a novel energy-resolved photon-counting (ERPC) detector for gamma ray imaging applications. The prototype ERPC detector has an active area of 4.4 cm × 4.4 cm, which is pixelated into 128 × 128 square pixels with a pitch size of 350 µm × 350µm. The current detector consists of multiple detector hybrids, each with a CdTe crystal of 1.1 cm × 2.2 cm × 1 mm, bump-bonded onto a custom-designed application-specific integrated circuit (ASIC). The ERPC ASIC has 2048 readout channels arranged in a 32 × 64 array. Each channel is equipped with pre- and shaping-amplifiers, a discriminator, peak/hold circuitry and an analog-to-digital converter (ADC) for digitizing the signal amplitude. In order to compensate for the pixel-to-pixel variation, two 8-bit digital-to-analog converters (DACs) are implemented into each channel for tuning the gain and offset. The ERPC detector is designed to offer a high spatial resolution, a wide dynamic range of 12-200 keV and a good energy resolution of 3-4 keV. The hybrid detector configuration provides a flexible detection area that can be easily tailored for different imaging applications. The intrinsic performance of a prototype ERPC detector was evaluated with various gamma ray sources, and the results are presented.

Results from a 64-pixel PIN-diode detector system for low-energy beta-electrons

NASA Astrophysics Data System (ADS)

Wuestling, Sascha; Fraenkle, F.; Habermehl, F.; Renschler, P.; Steidl, M.

2010-12-01

The KATRIN neutrino mass experiment is based on a precise energy measurement (Δ E/ E=5×10 -5) of electrons emerging from tritium beta decay ( Emax=18.6 keV). This is done by a large electrostatic retarding spectrometer (MAC-E Filter), which is followed by an electron detector. Key requirements for this detector are a large sensitive area (˜80 cm 2), a certain energy resolution (Δ E=600 eV @ 18.6 keV) but also a certain spatial resolution (˜3 mm), which leads to a multi-pixel design. As a tentative design on the way to the final detector, but also for operational service on the so-called pre-spectrometer experiment, a detector system with a reduced size (16 cm 2) and a reduced pixel number (64), making use of a monolithic segmented silicon PIN diode, was designed and built. While the design and very first measurements have been presented in Wuestling et al. [6], this publication shows the operational performance of the detector system. The robust concept of the electronics allowed adaptation to mechanically different experimental setups. The spacial resolution of the detector system proved to be essential in examining Penning trap induced background and other effects in the pre-spectrometer experiment. The detector performance test runs include energy resolution and calibration, background rates, correlation between pixels (crosstalk), spatially resolved rate analysis, and a dead-layer measurement [7]. The detector allows for background searches with a sensitivity as low as 1.3×10 -3 cps/cm 2 in the energy range of 20 keV. This allows the pre-spectrometer to be characterized with e-gun illumination with a signal to background ratio of better than 10 5 and the search for ultra low Penning discharge emissions.

Lightweight Hyperspectral Mapping System and a Novel Photogrammetric Processing Chain for UAV-based Sensing

NASA Astrophysics Data System (ADS)

Suomalainen, Juha; Franke, Jappe; Anders, Niels; Iqbal, Shahzad; Wenting, Philip; Becker, Rolf; Kooistra, Lammert

2014-05-01

We have developed a lightweight Hyperspectral Mapping System (HYMSY) and a novel processing chain for UAV based mapping. The HYMSY consists of a custom pushbroom spectrometer (range 450-950nm, FWHM 9nm, ~20 lines/s, 328 pixels/line), a consumer camera (collecting 16MPix raw image every 2 seconds), a GPS-Inertia Navigation System (GPS-INS), and synchronization and data storage units. The weight of the system at take-off is 2.0kg allowing us to mount it on a relatively small octocopter. The novel processing chain exploits photogrammetry in the georectification process of the hyperspectral data. At first stage the photos are processed in a photogrammetric software producing a high-resolution RGB orthomosaic, a Digital Surface Model (DSM), and photogrammetric UAV/camera position and attitude at the moment of each photo. These photogrammetric camera positions are then used to enhance the internal accuracy of GPS-INS data. These enhanced GPS-INS data are then used to project the hyperspectral data over the photogrammetric DSM, producing a georectified end product. The presented photogrammetric processing chain allows fully automated georectification of hyperspectral data using a compact GPS-INS unit while still producingin UAV use higher georeferencing accuracy than would be possible using the traditional processing method. During 2013, we have operated HYMSY on 150+ octocopter flights at 60+ sites or days. On typical flight we have produced for a 2-10ha area: a RGB orthoimagemosaic at 1-5cm resolution, a DSM in 5-10cm resolution, and hyperspectral datacube at 10-50cm resolution. The targets have mostly consisted of vegetated targets including potatoes, wheat, sugar beets, onions, tulips, coral reefs, and heathlands,. In this poster we present the Hyperspectral Mapping System and the photogrammetric processing chain with some of our first mapping results.

Rapid identification of pearl powder from Hyriopsis cumingii by Tri-step infrared spectroscopy combined with computer vision technology

NASA Astrophysics Data System (ADS)

Liu, Siqi; Wei, Wei; Bai, Zhiyi; Wang, Xichang; Li, Xiaohong; Wang, Chuanxian; Liu, Xia; Liu, Yuan; Xu, Changhua

2018-01-01

Pearl powder, an important raw material in cosmetics and Chinese patent medicines, is commonly uneven in quality and frequently adulterated with low-cost shell powder in the market. The aim of this study is to establish an adequate approach based on Tri-step infrared spectroscopy with enhancing resolution combined with chemometrics for qualitative identification of pearl powder originated from three different quality grades of pearls and quantitative prediction of the proportions of shell powder adulterated in pearl powder. Additionally, computer vision technology (E-eyes) can investigate the color difference among different pearl powders and make it traceable to the pearl quality trait-visual color categories. Though the different grades of pearl powder or adulterated pearl powder have almost identical IR spectra, SD-IR peak intensity at about 861 cm- 1 (v2 band) exhibited regular enhancement with the increasing quality grade of pearls, while the 1082 cm- 1 (v1 band), 712 cm- 1 and 699 cm- 1 (v4 band) were just the reverse. Contrastly, only the peak intensity at 862 cm- 1 was enhanced regularly with the increasing concentration of shell powder. Thus, the bands in the ranges of (1550-1350 cm- 1, 730-680 cm- 1) and (830-880 cm- 1, 690-725 cm- 1) could be exclusive ranges to discriminate three distinct pearl powders and identify adulteration, respectively. For massive sample analysis, a qualitative classification model and a quantitative prediction model based on IR spectra was established successfully by principal component analysis (PCA) and partial least squares (PLS), respectively. The developed method demonstrated great potential for pearl powder quality control and authenticity identification in a direct, holistic manner.

Rapid identification of pearl powder from Hyriopsis cumingii by Tri-step infrared spectroscopy combined with computer vision technology.

PubMed

Liu, Siqi; Wei, Wei; Bai, Zhiyi; Wang, Xichang; Li, Xiaohong; Wang, Chuanxian; Liu, Xia; Liu, Yuan; Xu, Changhua

2018-01-15

Pearl powder, an important raw material in cosmetics and Chinese patent medicines, is commonly uneven in quality and frequently adulterated with low-cost shell powder in the market. The aim of this study is to establish an adequate approach based on Tri-step infrared spectroscopy with enhancing resolution combined with chemometrics for qualitative identification of pearl powder originated from three different quality grades of pearls and quantitative prediction of the proportions of shell powder adulterated in pearl powder. Additionally, computer vision technology (E-eyes) can investigate the color difference among different pearl powders and make it traceable to the pearl quality trait-visual color categories. Though the different grades of pearl powder or adulterated pearl powder have almost identical IR spectra, SD-IR peak intensity at about 861cm -1 (v 2 band) exhibited regular enhancement with the increasing quality grade of pearls, while the 1082cm -1 (v 1 band), 712cm -1 and 699cm -1 (v 4 band) were just the reverse. Contrastly, only the peak intensity at 862cm -1 was enhanced regularly with the increasing concentration of shell powder. Thus, the bands in the ranges of (1550-1350cm -1 , 730-680cm -1 ) and (830-880cm -1 , 690-725cm -1 ) could be exclusive ranges to discriminate three distinct pearl powders and identify adulteration, respectively. For massive sample analysis, a qualitative classification model and a quantitative prediction model based on IR spectra was established successfully by principal component analysis (PCA) and partial least squares (PLS), respectively. The developed method demonstrated great potential for pearl powder quality control and authenticity identification in a direct, holistic manner. Copyright © 2017. Published by Elsevier B.V.

Use of fiber-optic DTS to investigate physical processes in thermohaline environments

NASA Astrophysics Data System (ADS)

Suarez, F. I.; Sarabia, A.; Silva, C.

2014-12-01

Salt-gradient solar ponds are artificial thermohaline environments that collect and store thermal energy for long time-periods. A solar pond consists of three distinctive zones: the upper convective zone, which is a thin layer of cooler, less salty water; the non-convective zone that has gradients in temperature and salinity; and the lower convective zone, a layer of high salinity brine where temperatures are the highest. The solar radiation that penetrates the upper layers of the pond reaches the lower convective zone and heats the high salinity brine, which does not rise beyond the lower convective zone because the effect of salinity on density is greater than the effect of temperature. The sediments beneath the pond are also heated due to the temperature increase in the lower convective zone, providing an additional volume for energy storage. To study the different physical processes occurring within a solar pond and its surroundings, we deployed a helicoidally wrapped distributed-temperature-sensing (DTS) system in a small-scale solar pond (1-m deep, 2.5-m long and 1.5-m width). In this installation, the pond is surrounded by a sandy soil that serves as an additional energy storage volume. The thermal profile is observed at a spatial sampling resolution of 1.1 cm (spatial resolution of 2.2. cm), a temporal resolution ranging from 15 s to 5 min, and a thermal resolution ranging from 0.05 to 0.5°C. These resolutions allow closing the energy balance and inferring physical processes such as double-diffusive convection, solar radiation absorption, and heat conduction through the sediments or through the non-convective zone. Independent thermal measurements are also being made to evaluate strengths and limitations of DTS systems in thermohaline environments, and to assess different calibration algorithms that have been proposed in the past.

Optical Comb from a Whispering Gallery Mode Resonator for Spectroscopy and Astronomy Instruments Calibration

NASA Technical Reports Server (NTRS)

Strekalov, Dmitry V.; Yu, Nam; Thompson, Robert J.

2012-01-01

The most accurate astronomical data is available from space-based observations that are not impeded by the Earth's atmosphere. Such measurements may require spectral samples taken as long as decades apart, with the 1 cm/s velocity precision integrated over a broad wavelength range. This raises the requirements specifically for instruments used in astrophysics research missions -- their stringent wavelength resolution and accuracy must be maintained over years and possibly decades. Therefore, a stable and broadband optical calibration technique compatible with spaceflights becomes essential. The space-based spectroscopic instruments need to be calibrated in situ, which puts forth specific requirements to the calibration sources, mainly concerned with their mass, power consumption, and reliability. A high-precision, high-resolution reference wavelength comb source for astronomical and astrophysics spectroscopic observations has been developed that is deployable in space. The optical comb will be used for wavelength calibrations of spectrographs and will enable Doppler measurements to better than 10 cm/s precision, one hundred times better than the current state-of-the- art.

The Jovian ionospheric E region

NASA Astrophysics Data System (ADS)

Kim, Y. H.; Fox, J. L.

1991-02-01

A model of the Jovian ionosphere was constructed, that includes direct photoionization of hydrocarbon molecules. A high-resolution solar spectrum was synthesized from Hinteregger's solar maximum spectrum (F79050N), and high-resolution cross sections for photoabsorption by H2 bands in the range 842 to 1116 A were constructed. Two strong solar lines and about 30 percent of the continuum flux between 912 and 1116 A penetrate below the methane homopause despite strong absorption by CH4 and H2. It is found that hydrocarbons (mainly C2H2 are ionized at a maximum rate of 55/cu cm per sec at 320 km above the ammonia cloud tops. The hydrocarbon ions produced are quickly converted to more complex hydrocarbon ions through reactions with CH4, C2H2, C2H6, and C2H4. It is found that a hydrocarbon ion layer is formed near 320 km that is about 50 km wide with a peak density in excess of 10,000/cu cm.

Recent Doppler Backscattering results from EAST tokamak

NASA Astrophysics Data System (ADS)

Zhou, Chu; Liu, Adi; Zhang, Xiaohui; Hu, Jianqiang; Wang, Mingyuan; Yu, Changxuan; Liu, Wandong; Li, Hong; Lan, Tao; Sun, Xuan; Xie, Jinlin; Ding, Weixing; CAS Key Laboratory of Geospace Environment, University of Science and Technology of China Team; Department of Physics and Astronomy, University of California at Los Angeles Collaboration

2013-10-01

A Doppler reflectometer system has recently been installed in the EAST tokamak. It includes two separated systems, one for Q-band and the other for V-band. The optical system consists of a fixed flat mirror and a steerable parabolic mirror, which enabling the measurement of perpendicular wave number in the range of 4-22/cm, with the wave number resolution around 2/cm, while the radial location can cover the whole minor radius for L mode and the whole pedestal for H mode on EAST. A 2D Gaussion Ray tracing code is used to calculate the scattering location, the perpendicular wave number and the resolution. In EAST last experimental campaign the Doppler shifted signals have been obtained and the radial profiles of the perpendicular propagation velocity during L-mode and H-mode are calculated. The Er evolution during L-H and H-L transition have also been measured. The two separated systems are also used as a poloidal coherent system together to study the GAM in EAST tokamak.

Characterization of a time-resolved non-contact scanning diffuse optical imaging system exploiting fast-gated single-photon avalanche diode detection

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

Di Sieno, Laura, E-mail: laura.disieno@polimi.it; Dalla Mora, Alberto; Contini, Davide

2016-03-15

We present a system for non-contact time-resolved diffuse reflectance imaging, based on small source-detector distance and high dynamic range measurements utilizing a fast-gated single-photon avalanche diode. The system is suitable for imaging of diffusive media without any contact with the sample and with a spatial resolution of about 1 cm at 1 cm depth. In order to objectively assess its performances, we adopted two standardized protocols developed for time-domain brain imagers. The related tests included the recording of the instrument response function of the setup and the responsivity of its detection system. Moreover, by using liquid turbid phantoms with absorbingmore » inclusions, depth-dependent contrast and contrast-to-noise ratio as well as lateral spatial resolution were measured. To illustrate the potentialities of the novel approach, the characteristics of the non-contact system are discussed and compared to those of a fiber-based brain imager.« less

Infrared near-field spectroscopy of trace explosives using an external cavity quantum cascade laser.

PubMed

Craig, Ian M; Taubman, Matthew S; Lea, A Scott; Phillips, Mark C; Josberger, Erik E; Raschke, Markus B

2013-12-16

Utilizing a broadly-tunable external cavity quantum cascade laser for scattering-type scanning near-field optical microscopy (s-SNOM), we measure infrared spectra of particles of explosives by probing characteristic nitro-group resonances in the 7.1-7.9 µm wavelength range. Measurements are presented with spectral resolution of 0.25 cm(-1), spatial resolution of 25 nm, sensitivity better than 100 attomoles, and at a rapid acquisition time of 90 s per spectrum. We demonstrate high reproducibility of the acquired s-SNOM spectra with very high signal-to-noise ratios and relative noise of <0.02 in self-homodyne detection.

High resolution eddy current microscopy

NASA Astrophysics Data System (ADS)

Lantz, M. A.; Jarvis, S. P.; Tokumoto, H.

2001-01-01

We describe a sensitive scanning force microscope based technique for measuring local variations in resistivity by monitoring changes in the eddy current induced damping of a cantilever with a magnetic tip oscillating above a conducting sample. To achieve a high sensitivity, we used a cantilever with an FeNdBLa particle mounted on the tip. Resistivity measurements are demonstrated on a silicon test structure with a staircase doping profile. Regions with resistivities of 0.0013, 0.0041, and 0.022 Ω cm are clearly resolved with a lateral resolution of approximately 180 nm. For this range of resistivities, the eddy current induced damping is found to depend linearly on the sample resistivity.

High-Rate Capable Floating Strip Micromegas

NASA Astrophysics Data System (ADS)

Bortfeldt, Jonathan; Bender, Michael; Biebel, Otmar; Danger, Helge; Flierl, Bernhard; Hertenberger, Ralf; Lösel, Philipp; Moll, Samuel; Parodi, Katia; Rinaldi, Ilaria; Ruschke, Alexander; Zibell, André

2016-04-01

We report on the optimization of discharge insensitive floating strip Micromegas (MICRO-MEsh GASeous) detectors, fit for use in high-energy muon spectrometers. The suitability of these detectors for particle tracking is shown in high-background environments and at very high particle fluxes up to 60 MHz/cm2. Measurement and simulation of the microscopic discharge behavior have demonstrated the excellent discharge tolerance. A floating strip Micromegas with an active area of 48 cm × 50 cm with 1920 copper anode strips exhibits in 120 GeV pion beams a spatial resolution of 50 μm at detection efficiencies above 95%. Pulse height, spatial resolution and detection efficiency are homogeneous over the detector. Reconstruction of particle track inclination in a single detector plane is discussed, optimum angular resolutions below 5° are observed. Systematic deviations of this μTPC-method are fully understood. The reconstruction capabilities for minimum ionizing muons are investigated in a 6.4 cm × 6.4 cm floating strip Micromegas under intense background irradiation of the whole active area with 20 MeV protons at a rate of 550 kHz. The spatial resolution for muons is not distorted by space charge effects. A 6.4 cm × 6.4 cm floating strip Micromegas doublet with low material budget is investigated in highly ionizing proton and carbon ion beams at particle rates between 2 MHz and 2 GHz. Stable operation up to the highest rates is observed, spatial resolution, detection efficiencies, the multi-hit and high-rate capability are discussed.

THE SPECTRUM OF Fe II

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

Nave, Gillian; Johansson, Sveneric, E-mail: gillian.nave@nist.gov

2013-01-15

The spectrum of singly ionized iron (Fe II) has been recorded using high-resolution Fourier transform (FT) and grating spectroscopy over the wavelength range 900 A to 5.5 {mu}m. The spectra were observed in high-current continuous and pulsed hollow cathode discharges using FT spectrometers at the Kitt Peak National Observatory, Tucson, AZ and Imperial College, London and with the 10.7 m Normal Incidence Spectrograph at the National Institute of Standards and Technology. Roughly 12,900 lines were classified using 1027 energy levels of Fe II that were optimized to measured wavenumbers. The wavenumber uncertainties of lines in the FT spectra range frommore » 10{sup -4} cm{sup -1} for strong lines around 4 {mu}m to 0.05 cm{sup -1} for weaker lines around 1500 A. The wavelength uncertainty of lines in the grating spectra is 0.005 A. The ionization energy of (130,655.4 {+-} 0.4) cm{sup -1} was estimated from the 3d{sup 6}({sup 5}D)5g and 3d{sup 6}({sup 5}D)6h levels.« less

High spectral resolution studies of gamma ray bursts on new missions

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

Desai, U. D.; Acuna, M. H.; Cline, T. L.

1996-08-01

Two new missions will be launched in 1996 and 1997, each carrying X-ray and gamma ray detectors capable of high spectral resolution at room temperature. The Argentine Satelite de Aplicaciones Cientificas (SAC-B) and the Small Spacecraft Technology Initiative (SSTI) Clark missions will each carry several arrays of X-ray detectors primarily intended for the study of solar flares and gamma-ray bursts. Arrays of small (1 cm{sup 2}) cadmium zinc telluride (CZT) units will provide x-ray measurements in the 10 to 80 keV range with an energy resolution of {approx_equal}6 keV. Arrays of both silicon avalanche photodiodes (APD) and P-intrinsic-N (PIN) photodiodesmore » (for the SAC-B mission only) will provide energy coverage from 2-25 keV with {approx_equal}1 keV resolution. For SAC-B, higher energy spectral data covering the 30-300 keV energy range will be provided by CsI(Tl) scintillators coupled to silicon APDs, resulting in similar resolution but greater simplicity relative to conventional CsI/PMT systems. Because of problems with the Pegasus launch vehicle, the launch of SAC-B has been delayed until 1997. The launch of the SSTI Clark mission is scheduled for June 1996.« less

Retrievals of Jovian Tropospheric Phosphine from Cassini/CIRS

NASA Technical Reports Server (NTRS)

Irwin, P. G. J.; Parrish, P.; Fouchet, T.; Calcutt, S. B.; Taylor, F. W.; Simon-Miller, A. A.; Nixon, C. A.

2004-01-01

On December 30th 2000, the Cassini-Huygens spacecraft reached the perijove milestone on its continuing journey to the Saturnian system. During an extended six-month encounter, the Composite Infrared Spectrometer (CIRS) returned spectra of the Jovian atmosphere, rings and satellites from 10-1400 cm(exp -1) (1000-7 microns) at a programmable spectral resolution of 0.5 to 15 cm(exp -1). The improved spectral resolution of CIRS over previous IR instrument-missions to Jupiter, the extended spectral range, and higher signal-to-noise performance provide significant advantages over previous data sets. CIRS global observations of the mid-infrared spectrum of Jupiter at medium resolution (2.5 cm(exp -1)) have been analysed both with a radiance differencing scheme and an optimal estimation retrieval model to retrieve the spatial variation of phosphine and ammonia fractional scale height in the troposphere between 60 deg S and 60 deg N at a spatial resolution of 6 deg. The ammonia fractional scale height appears to be high over the Equatorial Zone (EZ) but low over the North Equatorial Belt (NEB) and South Equatorial Belt (SEB) indicating rapid uplift or strong vertical mixing in the EZ. The abundance of phosphine shows a similar strong latitudinal variation which generally matches that of the ammonia fractional scale height. However while the ammonia fractional scale height distribution is to a first order symmetric in latitude, the phosphine distribution shows a North/South asymmetry at mid latitudes with higher amounts detected at 40 deg N than 40 deg S. In addition the data show that while the ammonia fractional scale height at this spatial resolution appears to be low over the Great Red Spot (GRS), indicating reduced vertical mixing above the approx. 500 mb level, the abundance of phosphine at deeper levels may be enhanced at the northern edge of the GRS indicating upwelling.

Theory of compressive modeling and simulation

NASA Astrophysics Data System (ADS)

Szu, Harold; Cha, Jae; Espinola, Richard L.; Krapels, Keith

2013-05-01

Modeling and Simulation (M&S) has been evolving along two general directions: (i) data-rich approach suffering the curse of dimensionality and (ii) equation-rich approach suffering computing power and turnaround time. We suggest a third approach. We call it (iii) compressive M&S (CM&S); because the basic Minimum Free-Helmholtz Energy (MFE) facilitating CM&S can reproduce and generalize Candes, Romberg, Tao & Donoho (CRT&D) Compressive Sensing (CS) paradigm as a linear Lagrange Constraint Neural network (LCNN) algorithm. CM&S based MFE can generalize LCNN to 2nd order as Nonlinear augmented LCNN. For example, during the sunset, we can avoid a reddish bias of sunlight illumination due to a long-range Rayleigh scattering over the horizon. With CM&S we can take instead of day camera, a night vision camera. We decomposed long wave infrared (LWIR) band with filter into 2 vector components (8~10μm and 10~12μm) and used LCNN to find pixel by pixel the map of Emissive-Equivalent Planck Radiation Sources (EPRS). Then, we up-shifted consistently, according to de-mixed sources map, to the sub-micron RGB color image. Moreover, the night vision imaging can also be down-shifted at Passive Millimeter Wave (PMMW) imaging, suffering less blur owing to dusty smokes scattering and enjoying apparent smoothness of surface reflectivity of man-made objects under the Rayleigh resolution. One loses three orders of magnitudes in the spatial Rayleigh resolution; but gains two orders of magnitude in the reflectivity, and gains another two orders in the propagation without obscuring smog . Since CM&S can generate missing data and hard to get dynamic transients, CM&S can reduce unnecessary measurements and their associated cost and computing in the sense of super-saving CS: measuring one & getting one's neighborhood free .

Lack of robustness of textural measures obtained from 3D brain tumor MRIs impose a need for standardization.

PubMed

Molina, David; Pérez-Beteta, Julián; Martínez-González, Alicia; Martino, Juan; Velasquez, Carlos; Arana, Estanislao; Pérez-García, Víctor M

2017-01-01

Textural measures have been widely explored as imaging biomarkers in cancer. However, their robustness under dynamic range and spatial resolution changes in brain 3D magnetic resonance images (MRI) has not been assessed. The aim of this work was to study potential variations of textural measures due to changes in MRI protocols. Twenty patients harboring glioblastoma with pretreatment 3D T1-weighted MRIs were included in the study. Four different spatial resolution combinations and three dynamic ranges were studied for each patient. Sixteen three-dimensional textural heterogeneity measures were computed for each patient and configuration including co-occurrence matrices (CM) features and run-length matrices (RLM) features. The coefficient of variation was used to assess the robustness of the measures in two series of experiments corresponding to (i) changing the dynamic range and (ii) changing the matrix size. No textural measures were robust under dynamic range changes. Entropy was the only textural feature robust under spatial resolution changes (coefficient of variation under 10% in all cases). Textural measures of three-dimensional brain tumor images are not robust neither under dynamic range nor under matrix size changes. Standards should be harmonized to use textural features as imaging biomarkers in radiomic-based studies. The implications of this work go beyond the specific tumor type studied here and pose the need for standardization in textural feature calculation of oncological images.

TUNABLE DIODE LASER MEASUREMENTS OF NO2 NEAR 670 NM AND 395 NM. (R823933)

EPA Science Inventory

Two single-mode diode lasers were used to record high-resolution absorption spectra of NO2 (dilute in Ar) near 670.2 and 394.5 nm over a range of temperatures (296 to 774 K) and total pressures (2.4 x 10(-2) to 1 atm). A commercial InGaAsP laser was tuned 1.3 cm(-1) at a repetiti...

The High Energy Particle Detector (HEPD) for the CSES satellite

NASA Astrophysics Data System (ADS)

Sparvoli, Roberta

2016-04-01

We present the advanced High Energy Particle Detector (HEPD) developed to be installed on the China Seismo-Electromagnetic Satellite (CSES), launch scheduled by the end of 2016. The HEPD instrument aims at studying the temporal stability of the inner Van Allen radiation belts and at investigating precipitation of trapped particles induced by magnetospheric, ionosferic and tropospheric EM emissions, as well as by the seismo-electromagnetic and anthropogenic disturbances. In occasion of many earthquakes and volcanic eruptions, several measurements, on ground and by experiments on LEO satellites revealed: electromagnetic and plasma perturbations, and anomalous increases of high-energy Van Allen charged particle flux. The precipitation of trapped electrons and protons (from a few MeV to several tens of MeV) could be induced by diffusion of particles pitch-angle possibly caused by the seismo-electromagnetic emissions generated before (a few hours) earthquakes. Due to the longitudinal drift along a same L-shell, anomalous particle bursts of precipitating particles could be detected by satellites not only on the epicentral area of the incoming earthquake, but along the drift path. Moreover, the opposite drift directions of positive and negative particles could allow reconstructing the longitude of the earthquake focal area. Although, the earthquake prediction is not within the reach of current knowledge, however the study of the precursors aims at collecting all relevant information that can infer the spatial and temporal coordinates of the seismic events from measurements. At this purposes, it is essential to detect particles in a wide range of energies (because particles of different energies are sensitive to different frequencies of seismo-electromagnetic emissions), with a good angular resolution (in order to separate fluxes of trapped and precipitating particles), and excellent ability to recognize the charge (that determines the direction of the longitudinal drift of precipitating particles). The East-West or West-East drift direction is an essential information to retrieve the longitude of the starting point of the burst precipitation and then to reconstruct the geographical area where the interaction between particles and seismo-electromagnetic emissions occurred. HEPD has been designed to provide good energy resolution and high angular resolution for electrons (3 - 100 MeV) and proton (30 - 200 MeV). The detector consists of two layers of segmented plastic scintillators and a calorimeter, constituted by a tower of scintillator counters. The direction of the incident particle is provided by two planes of double-side silicon micro-strip detectors placed in front of the trigger scintillator planes to limit the effect of Coulomb multiple scattering on the direction measurement. The electron angular resolution varies between 13° at 2.5 MeV and ≤ 1° for energies above 35 MeV. The detector has a wide angular acceptance (>60°) over the full energy range 2.5-100 MeV. The angle-integrated, total acceptance is larger than 100 cm2sr between 2.5 and 35 MeV, decreasing at higher energies (about 40 cm2sr at 100 MeV). The proton angular resolution is ≤1° over the full detection range. The proton integrated-angle, total acceptance is larger than 100 cm2sr between 30 MeV and 150 MeV, decreasing to 60 cm2sr at 200 MeV. The good energy-loss measurement of the silicon track, combined with the energy resolution of the scintillators and calorimeter, allows identifying electrons with acceptable proton background levels (10-5-10-3).

The Next-Generation Very Large Array: Technical Overview

NASA Astrophysics Data System (ADS)

McKinnon, Mark; Selina, Rob

2018-01-01

As part of its mandate as a national observatory, the NRAO is looking toward the long range future of radio astronomy and fostering the long term growth of the US astronomical community. NRAO has sponsored a series of science and technical community meetings to consider the science mission and design of a next-generation Very Large Array (ngVLA), building on the legacies of the Atacama Large Millimeter/submillimeter Array (ALMA) and the Very Large Array (VLA).The basic ngVLA design emerging from these discussions is an interferometric array with approximately ten times the sensitivity and ten times higher spatial resolution than the VLA and ALMA radio telescopes, optimized for operation in the wavelength range 0.3cm to 3cm. The ngVLA would open a new window on the Universe through ultra-sensitive imaging of thermal line and continuum emission down to milli-arcsecond resolution, as well as unprecedented broadband continuum polarimetric imaging of non-thermal processes. The specifications and concepts for major ngVLA system elements are rapidly converging.We will provide an overview of the current system design of the ngVLA. The concepts for major system elements such as the antenna, receiving electronics, and central signal processing will be presented. We will also describe the major development activities that are presently underway to advance the design.

Monolithic liquid crystal waveguide Fourier transform spectrometer for gas species sensing

NASA Astrophysics Data System (ADS)

Chao, Tien-Hsin; Lu, Thomas T.; Davis, Scott R.; Rommel, Scott D.; Farca, George; Luey, Ben; Martin, Alan; Anderson, Michael H.

2011-04-01

Jet Propulsion Lab and Vescent Photonics Inc. and are jointly developing an innovative ultracompact (volume < 10 cm3), ultra-low power (<10-3 Watt-hours per measurement and zero power consumption when not measuring), completely non-mechanical Liquid Crystal Waveguide Fourier Transform Spectrometer (LCWFTS) that will be suitable for a variety of remote-platform, in-situ measurements. These devices are made possible by novel electro-evanescent waveguide architecture, enabling "monolithic chip-scale" Electro Optic-FTS (EO-FTS) sensors. The potential performance of these EO-FTS sensors include: i) a spectral range throughout 0.4-5 μm (25000 - 2000 cm-1), ii) high-resolution (Δλ <= 0.1 nm), iii) high-speed (< 1 ms) measurements, and iv) rugged integrated optical construction. This performance potential enables the detection and quantification of a large number of different atmospheric gases simultaneously in the same air mass and the rugged construction will enable deployment on previously inaccessible platforms. The sensor construction is also amenable for analyzing aqueous samples on remote floating or submerged platforms. We will report a proof-of-principle prototype LCWFTS sensor that has been demonstrated in the near-IR (range of 1450-1700 nm) with a 5 nm resolution. This performance is in good agreement with theoretical models, which are being used to design and build the next generation LCWFTS devices.

Design of MiSolFA Hard X-Ray Imager

NASA Astrophysics Data System (ADS)

Lastufka, Erica; Casadei, Diego

2017-08-01

Advances in the study of coronal electron-accelerating regions have so far been limited by the dynamic range of X-ray instruments. A quick and economical alternative to desirable focusing optics technology is stereo observation. The micro-satellite MiSolFA (Micro Solar-Flare Apparatus) is designed both as a stand-alone X-ray imaging spectrometer and a complement to the Spectrometer/Telescope for Imaging X-rays (STIX) mission. These instruments will be the first pair of cross-calibrated X-ray imaging spectrometers to look at solar flares from very different points of view. MiSolFA will achieve indirect imaging between 10 and 60 keV and provide spectroscopy up to 100 keV, equipped with grids producing moiré patterns in a similar way to STIX. New manufacturing techniques produce gold gratings on a graphite or silicon substrate, with periods ranging from 15 to 225 micrometers, separated by a distance of 15.47 cm, to achieve a spatial resolutions from 10" to 60" (as compared to RHESSI's separation of 150 cm and 1" resolution). We present the progress of the imager design, the performance of the first prototypes, and reach out to the community for further scientific objectives to consider in optimizing the final design.

Role of Er3+ concentration in high-resolution spectra of BaY2 F8 single crystals

NASA Astrophysics Data System (ADS)

Baraldi, A.; Capelletti, R.; Mazzera, M.; Ponzoni, A.; Amoretti, G.; Magnani, N.; Toncelli, A.; Tonelli, M.

2005-08-01

Fourier transform absorption spectroscopy with a resolution as fine as 0.02cm-1 was applied to Er3+ -doped monoclinic BaY2F8 laser crystals in a wide wave number range (500-24000cm-1) and in the temperature range 9-300 K. The careful analysis of the complex narrow line spectra induced by Er3+ allowed us to determine with high accuracy the crystal field splitting of the fundamental I15/24 and of the excited I13/24 , I11/24 , I9/24 , F9/24 , S3/24 , H11/22 , F7/24 , F5/24 , and F3/24 manifolds. On the basis of the experimental data, the crystal-field parameters were determined and Newman’s superposition model was applied: in this way a slight displacement of Er3+ with respect to the Y3+ position was foreseen. The Judd-Ofelt parameters were evaluated: the lifetime values deduced from them were compared to the experimental ones and discussed. The effects caused by increasing Er3+ concentrations (0.5%, 2%, 12%, and 20% atomic fraction) were studied in detail. The new lines, the line broadening, and the line-shape changes were explained in terms of Er3+-Er3+ interaction.

Rapid spectral and flux time variations in a solar burst observed at various dm-mm wavelengths and at hard X-rays

NASA Technical Reports Server (NTRS)

Zodivaz, A. M.; Kaufmann, P.; Correia, E.; Costa, J. E. R.; Takakura, T.; Cliver, E. W.; Tapping, K. F.

1986-01-01

A solar burst was observed with high sensitivity and time resolution at cm-mm wavelengths by two different radio observatories (Itapetinga and Algonquin), with high spectral time resolution at dm-mm wavelengths by patrol instruments (Sagamore Hill), and at hard X-rays (HXM Hinotori). At the onset of the major burst time structure there was a rapid rise in the spectral turnover frequency (from 5 to 15 GHz), in about 10s, coincident to a reduction of the spectral index in the optically thin part of the spectrum. The burst maxima were not time coincident at the optically thin radio frequencies and at the different hard X-ray energy ranges. The profiles at higher radio frequencies exhibited better time coincidence to the high energy X-rays. The hardest X-ray spectrum (-3) coincided with peak radio emission at the higher frequency (44 GHz). The event appeared to be built up by a first major injection of softer particles followed by other injections of harder particles. Ultrafast time structures were identified as superimposed on the burst emission at the cm-mm high sensitivity data at X-rays, with predominant repetition rates ranging from 2.0 to 3.5 Hz.

Application of spatially resolved high resolution crystal spectrometry to inertial confinement fusion plasmas.

PubMed

Hill, K W; Bitter, M; Delgado-Aparacio, L; Pablant, N A; Beiersdorfer, P; Schneider, M; Widmann, K; Sanchez del Rio, M; Zhang, L

2012-10-01

High resolution (λ∕Δλ ∼ 10 000) 1D imaging x-ray spectroscopy using a spherically bent crystal and a 2D hybrid pixel array detector is used world wide for Doppler measurements of ion-temperature and plasma flow-velocity profiles in magnetic confinement fusion plasmas. Meter sized plasmas are diagnosed with cm spatial resolution and 10 ms time resolution. This concept can also be used as a diagnostic of small sources, such as inertial confinement fusion plasmas and targets on x-ray light source beam lines, with spatial resolution of micrometers, as demonstrated by laboratory experiments using a 250-μm (55)Fe source, and by ray-tracing calculations. Throughput calculations agree with measurements, and predict detector counts in the range 10(-8)-10(-6) times source x-rays, depending on crystal reflectivity and spectrometer geometry. Results of the lab demonstrations, application of the technique to the National Ignition Facility (NIF), and predictions of performance on NIF will be presented.

Speed-dependent Voigt lineshape parameter database from dual frequency comb measurements up to 1305 K. Part I: Pure H2O absorption, 6801-7188 cm-1

NASA Astrophysics Data System (ADS)

Schroeder, Paul J.; Cich, Matthew J.; Yang, Jinyu; Giorgetta, Fabrizio R.; Swann, William C.; Coddington, Ian; Newbury, Nathan R.; Drouin, Brian J.; Rieker, Gregory B.

2018-05-01

We measure speed-dependent Voigt lineshape parameters with temperature-dependence exponents for several hundred spectroscopic features of pure water spanning 6801-7188 cm-1. The parameters are extracted from broad bandwidth, high-resolution dual frequency comb absorption spectra with multispectrum fitting techniques. The data encompass 25 spectra ranging from 296 K to 1305 K and 1 to 17 Torr of pure water vapor. We present the extracted parameters, compare them to published data, and present speed-dependence, self-shift, and self-broadening temperature-dependent parameters for the first time. Lineshape data is extracted using a quadratic speed-dependent Voigt profile and a single self-broadening power law temperature-dependence exponent over the entire temperature range. The results represent an important step toward a new high-temperature database using advanced lineshape profiles.

MEMS based Doppler velocity measurement system

NASA Astrophysics Data System (ADS)

Shin, Minchul

The design, fabrication, modeling and characterization of a capacitive micromachined ultrasonic transducer (cMUT) based in-air Doppler velocity measurement system using a 1 cm2 planar array are described. Continuous wave operation in a narrowband was chosen in order to maximize range, as it allows for better rejection of broadband noise. The sensor array has a 160-185 kHz resonant frequency to achieve a 10 degree beamwidth. A model for the cMUT and the acoustic system which includes electrical, mechanical, and acoustic components is provided. Furthermore, characterization of the cMUT sensor with a variety of testing procedures is provided. Laser Doppler vibrometry (LDV), beampattern, reflection, and velocity testing characterize the performance of the sensors. The sensor is capable of measuring the velocity of a moving specular reflector with a resolution of 5 cm/s, an update rate of 0.016 second, and a range of 1.5 m.

Electron-density-sensitive Line Ratios of Fe xiii– xvi from Laboratory Sources Compared to CHIANTI

DOE PAGES

Weller, M. E.; Beiersdorfer, P.; Soukhanovskii, V. A.; ...

2018-02-15

We present electron-density-sensitive line ratios for Fe xiii– xvi measured in the spectral wavelength range of 200–440 Å and an electron density range of (1-4) × 10 13 cm -3. The results provide a test at the high-density limit of density-sensitive line ratios useful for astrophysical studies. The measurements were performed on the National Spherical Torus Experiment-Upgrade, where electron densities were measured independently by the laser Thomson scattering diagnostic. Spectra were collected with a flat-field grazing-incidence spectrometer, which provided a spectral resolution of up to 0.3 Å, i.e., high resolution across the broad wavelength range. The response of the instrumentmore » was relatively calibrated using spectroscopic techniques in order to improve accuracy. Lastly, the line ratios are compared to other laboratory sources and the latest version of CHIANTI (8.0.2), and an agreement within 30% is found.« less

Electron-density-sensitive Line Ratios of Fe xiii– xvi from Laboratory Sources Compared to CHIANTI

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

Weller, M. E.; Beiersdorfer, P.; Soukhanovskii, V. A.

We present electron-density-sensitive line ratios for Fe xiii– xvi measured in the spectral wavelength range of 200–440 Å and an electron density range of (1-4) × 10 13 cm -3. The results provide a test at the high-density limit of density-sensitive line ratios useful for astrophysical studies. The measurements were performed on the National Spherical Torus Experiment-Upgrade, where electron densities were measured independently by the laser Thomson scattering diagnostic. Spectra were collected with a flat-field grazing-incidence spectrometer, which provided a spectral resolution of up to 0.3 Å, i.e., high resolution across the broad wavelength range. The response of the instrumentmore » was relatively calibrated using spectroscopic techniques in order to improve accuracy. Lastly, the line ratios are compared to other laboratory sources and the latest version of CHIANTI (8.0.2), and an agreement within 30% is found.« less

SU-F-I-55: Performance Evaluation of Digital PET/CT: Medical Physics Basis for the Clinical Applications

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

Zhang, J; Knopp, MV; Miller, M

2016-06-15

Purpose: Replacement of conventional PMT-based detector with next generation digital photon counting (DPC) detector is a technology leap for PET imaging. This study evaluated the performance and characteristics of the DPC system and its stability within a 1 year time window following its installation focusing on the medical physics basis for clinical applications. Methods: A digital PET/CT scanner using 1:1 coupling of 23,040 crystal: detector elements was introduced and became operational at OSU. We tested and evaluated system performance and characteristics using NEMA NU2-2012. System stabilities in timing resolution, energy resolution, detector temperature and humidity (T&H) were monitored over 1-yr.more » Timing, energy and spatial resolution were characterized across clinically relevant count rate range. CQIE uniformity PET and NEMA IEC-Body PET with hot spheres varying with sizes and contrasts were performed. PET reconstructed in standard(4mm), High(2mm) and Ultra-High(1mm) definitions were evaluated. Results: NEMA results showed PET spatial resolution (mm-FWHM) from 4.01&4.14 at 1cm to 5.82&6.17 at 20cm in transverse & axial. 322±3ps timing and 11.0% energy resolution were measured. 5.7kcps/MBq system sensitivity with 24kcps/MBq effective sensitivity was obtained. The peak-NECR was ∼171kcps with the effective peak-NECR >650kcps@50kBq/mL. Scatter fraction was ∼30%, and the maximum trues was >900kcps. NEMA IQ demonstrated hot sphere contrast ranging from ∼62%±2%(10mm) to ∼88%±2%(22mm), cold sphere contrast of ∼86%±2%(28mm) and ∼89%±3%(37mm) and excellent uniformity. Monitoring 1-yr stability, it revealed ∼1% change in timing, ±0.4% change in energy resolution, and <10% variations in T&H. CQIE PET gave <3% SUV variances in axial. 60%–100% recovery coefficients across sphere sizes and contrast levels were achieved. Conclusion: Characteristics and stability of the next generation DPC PET detector system over an 1-yr time window was excellent and better than prior experiences. It demonstrated improved and robust system characteristics and performance in spatial resolution, sensitivity, timing and energy resolution, count rate and image quality. Michael Miller is an employee of Philips Healthcare.« less

Investigation of dissolved organic substances in the Northern Dvina under different hydrological seasons

NASA Astrophysics Data System (ADS)

Shorina, Natalia; Spencer, Robert; Klimov, Sergey; Bulygina, Ekaterina; Ladesov, Anton; Shestakov, Semen; Vorobieva, Taisia

2017-04-01

The rivers of the Russian Arctic, which include the Northern Dvina, are important sources of organic matter of terrestrial origin to the seas of the Arctic Ocean. The Northern Dvina River accounts for 50% of the entire flow of the river system to the White Sea. The spring freshet period accounts for 60% of the annual hydrological flow, and 80% of the annual flow of riverine suspended sediment. Despite the importance of the study of organic matter in dissolved form for global carbon cycling, this topic has received little attention in this region of Russia. This paper presents results from a study examining dissolved organic matter (DOM) in the Northern Dvina River encompassing different hydrological seasons, utilizing a range of methods for isolation and concentration. The goal of this study was to characterize the molecular features of DOM in the Northern Dvina River across the seasonal hydrograph. IR spectra of the samples were recorded on a FTIR spectrometer Vertex 70 (Bruker, Germany), with a resolution of 4 cm-1, measuring the range 4000-400 cm-1 and 128 recorded parallel determinations. The absorption band at 3200cm-1 and 1600 cm-1 are due to OH group. In the range of 2800-3000 cm-1 we observed bands due to methyl, methylene groups, and possibly the presence of nitrogen-containing C = NH groups. In the area of 1710 cm-1 there is a strong band of carbonyl groups characteristic of aldehydes, ketones and carboxylic acids. The mild band at 1450 cm-1 is noted and can be attributed to the C-C vibrations of the aromatic ring. In the range of 1100-1000 cm-1 is observed a band related to C-O groups. The absorption bands at 1030 cm-1 correspond to C-O-C symmetric stretching vibrations, and at the 1150 cm-1 belongs to the aromatic C-H-planar deformation fluctuations. Based on data from the infrared spectrometry, it should be noted that along with the strongly expressed aliphatic component, studied samples are characterized by the presence of aromatic ring groups. An important contribution of aliphatic groups and the presence of aromatic structures are also confirmed with solid-state NMR spectroscopy (NMR spectrometer Bruker AVANCE III ™ 600). The relative intensity was normalized by the intensity of the weakest signal, the spectrum was deconvoluted to separate signals. Methods of cross-polarization 1H-13C and magic angle spinning (CP/MAS) were used in order to improve the resolution (spinning rate was 12 kHz). The spectrum was registered for 13C, the number of scans was 2048 and the relaxation delay was 5 s. According to the GPC molecular weight distribution, DOM samples analyzed from during the autumn floods from the Northern Dvina River are 10kDA, which corresponds to the molecular masses of fulvic acids. This data is the first obtained describing structural group DOM components from the Northern Dvina River methods using IR and NMR spectroscopy. Comparative analysis of the DOM samples obtained at different hydrological seasons and using different methods of selection and concentration, highlights the predominance of aliphatic structure in comparison to the aromatic component, which indicates a high replacement hydrocarbon skeleton in the samples studied. The study was sponsored by program UB RAS №0410-2015-0027; FANO Russian project number 0410-2014-0030, on the devices of joint use Centre of scientific equipment «Arctic» N(Ar)FU

Tropospheric Emission Spectrometer for the Earth Observing System

NASA Technical Reports Server (NTRS)

Glavich, Thomas A.; Beer, Reinhard

1991-01-01

A Tropospheric Emission Spectrometer (TES) for the Earth Observing System (EOS) series of polar-orbiting platforms is described. TES is aimed at studying tropospheric chemistry, in particular, the exchange of gases between the surface and the atmosphere, urban and regional pollution, acid rain precursors, sources and sinks of greenhouse gases, and the interchange of gases between the troposphere and the stratosphere. TES is a high-resolution (0.025/cm) infrared Fourier transform spectrometer operating in the passive thermal-emission mode in a very wide spectral range (600 to 4350/cm; 2.3 to 16.7 microns). TES has 32 spatial pixels in each of four optically conjugated linear detector arrays, each optimized for a different spectral region.

A possible line feature at 73 keV from the Crab Nebula

NASA Technical Reports Server (NTRS)

Ling, J. C.; Mahoney, W. A.; Willett, J. B.; Jacobson, A. S.

1979-01-01

Evidence is reported for a possible line feature at 73 keV from the Crab Nebula. The experiment was conducted with a balloon-borne high-resolution gamma-ray spectrometer on June 10, 1974, over Palestine, Texas. The intensity and the width of the line derived from the fitting of these data are approximately 0.0038 photon per (sq cm-sec) and less than 4.9 keV FWHM, respectively. The line is superposed on a power-law continuum of 11.2 E to the -2.16 photons per (sq cm-keV) in the energy range from 53 to 300 keV, which is consistent with other measurements of the Crab Nebula spectrum.

[Application of near-infrared diffuse reflectance spectroscopy to the detection and identification of transgenic corn].

PubMed

Rui, Yu-kui; Luo, Yun-bo; Huang, Kun-lun; Wang, Wei-min; Zhang, Lu-da

2005-10-01

With the rapid development of the GMO, more and more GMO food has been pouring into the market. Much attention has been paid to GMO labeling under the controversy of GMO safety. Transgenic corns and their parents were scanned by continuous wave of near infrared diffuse reflectance spectroscopy range of 12000-4000 cm(-1); the resolution was 4 cm(-1); scanning was carried out for 64 times; BP algorithm was applied for data processing. The GMO food was easily resolved. Near-infrared diffuse reflectance spectroscopy is unpolluted and inexpensive compared with PCR and ELISA, so it is a very promising detection method for GMO food.

Use of PTFE Stent Grafts for Hemodialysis-related Central Venous Occlusions: Intermediate-Term Results

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

Kundu, Sanjoy, E-mail: sanjoy_kundu40@hotmail.com; Modabber, Milad; You, John M.

2011-10-15

Purpose: To assess the safety and effectiveness of a polytetrafluoroethylene (PTFE) encapsulated nitinol stents (Bard Peripheral Vascular, Tempe, AZ) for treatment of hemodialysis-related central venous occlusions. Materials and Methods: Study design was a single-center nonrandomized retrospective cohort of patients from May 2004 to August 2009 for a total of 64 months. There were 14 patients (mean age 60 years, range 50-83 years; 13 male, 1 female). All patients had autogenous fistulas. All 14 patients had central venous occlusions and presented with clinical symptoms of the following: extremity swelling (14%, 2 of 14), extremity and face swelling (72%, 10 of 14),more » and face swelling/edema (14%, 2 of 14). There was evidence of access dysfunction with decreased access flow in 36% (5 of 14) patients. There were prior interventions or previous line placement at the site of the central venous lesion in all 14 patients. Results were assessed by recurrence of clinical symptoms and function of the access circuit (National Kidney Foundation recommended criteria). Results: Sixteen consecutive straight stent grafts were implanted in 14 patients. Average treated lesion length was 5.0 cm (range, 0.9-7 cm). All 14 patients had complete central venous occlusion (100% stenosis). The central venous occlusions were located as follows: right subclavian and brachiocephalic vein (21%, 3 of 14), right brachiocephalic vein (36%, 5 of 14), left brachiocephalic vein (36%, 5 of 14), and bilateral brachiocephalic vein (7%, 1 of 14). A total of 16 PTFE stent grafts were placed. Ten- or 12-mm-diameter PTFE stent grafts were placed. The average stent length was 6.1 cm (range, 4-8 cm). Technical (deployment), anatomic (<30% residual stenosis), clinical (resolution of symptoms), and hemodynamic (resolution of access dysfunction) success were 100%. At 3, 6, and 9 months, primary patency of the treated area and access circuit were 100% (14 of 14). Conclusions: This PTFE encapsulated stent graft demonstrates encouraging intermediate-term patency results for central vein occlusions. Further prospective studies with long-term assessment and larger patient populations will be required.« less

SU-G-IeP3-07: High-Resolution, High-Sensitivity Imaging and Quantification of Intratumoral Distributions of Gold Nanoparticles Using a Benchtop L-Shell XRF Imaging System

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

Manohar, N; Diagaradjane, P; Krishnan, S

2016-06-15

Purpose: To demonstrate the ability to perform high-resolution imaging and quantification of sparse distributions of gold nanoparticles (GNPs) within ex vivo tumor samples using a highly-sensitive benchtop L-shell x-ray fluorescence (XRF) imaging system. Methods: An optimized L-shell XRF imaging system was assembled using a tungsten-target x-ray source (operated at 62 kVp and 45 mA). The x-rays were filtered (copper: 0.08 mm & aluminum: 0.04 mm) and collimated (lead: 5 cm thickness, 3 cm aperture diameter) into a cone-beam in order to irradiate small samples or objects. A collimated (stainless steel: 4 cm thickness, 2 mm aperture diameter) silicon drift detector,more » capable of 2D translation, was placed at 90° with respect to the beam to acquire XRF/scatter spectra from regions of interest. Spectral processing involved extracting XRF signal from background, followed by attenuation correction using a Compton scatter-based normalization algorithm. Calibration phantoms with water/GNPs (0 and 0.00001–10 mg/cm{sup 3}) were used to determine the detection limit of the system at a 10-second acquisition time. The system was then used to map the distribution of GNPs within a 12×11×2 mm{sup 3} slice excised from the center of a GNP-loaded ex vivo murine tumor sample; a total of 110 voxels (2.65×10{sup −3} cm{sup 3}) were imaged with 1.3-mm spatial resolution. Results: The detection limit of the current cone-beam benchtop L-shell XRF system was 0.003 mg/cm{sup 3} (3 ppm). Intratumoral GNP concentrations ranging from 0.003 mg/cm{sup 3} (3 ppm) to a maximum of 0.055 mg/cm{sup 3} (55 ppm) and average of 0.0093 mg/cm{sup 3} (9.3 ppm) were imaged successfully within the ex vivo tumor slice. Conclusion: The developed cone-beam benchtop L-shell XRF imaging system can immediately be used for imaging of ex vivo tumor samples containing low concentrations of GNPs. With minor finetuning/optimization, the system can be directly adapted for performing routine preclinical in vivo imaging tasks. Supported by NIH/NCI grant R01CA155446 This investigation was supported by NIH/NCI grant R01CA155446.« less

The Raman spectrum of Ca-Mg-Fe carbonates; Applications in geobiology

NASA Astrophysics Data System (ADS)

van Zuilen, M. A.; Rividi, N.; Ménez, B.; Philippot, P.

2012-04-01

Carbonates form a very important mineral group in geobiological studies. They are a common mineral matrix for putative carbonaceous microfossils in Archean greenstone belts, form an important chemical deposit in seafloor hydrothermal systems, and are a common product in biomineralization processes. In many geobiological studies there is a specific need for simple characterization of carbonate composition while avoiding complex sample preparation or sample destruction. Raman spectroscopy is a highly versatile non-destructive technique enabling in-situ characterization of minerals and carbonaceous materials. It can be combined with confocal microscopy enabling high-resolution Raman mapping of entire rock thin sections, or can be integrated in submersibles and potentially Mars-rovers for direct field-based mineral identification. It is thus important that well-established spectral databases exist which enable unambiguous identification of a wide variety of carbonate minerals. The most common carbonates in the Ca-Mg-Fe system include the CaCO3 polymorphs calcite, aragonite, and vaterite, as well as the solid solutions CaMg(CO3)2-CaFe(CO3)2 (dolomite-ankerite) and MgCO3-FeCO3 (magnesite-siderite). Although various carbonate end-members have been studied exhaustively by Raman spectroscopy, a simple protocol for rapid distinction of various carbonate solid solutions is still lacking. Here we present a detailed study of Raman shifts in various carbonate standards of known composition in the Ca-Mg-Fe system. Carbonates with rhombohedral symmetry display a Raman spectrum with six characteristic vibrational modes - four of these represent vibrations within the (CO3)2- unit and two represent external vibrations of the crystal lattice. We show that Raman band shifts of internal mode 2ν2 (range 1725-1765 cm-1), and external modes T (range 170-215 cm-1) and L (range 285-330 cm-1) for siderite-magnesite and ankerite-dolomite solid solutions display distinct and well defined positive correlations with Mg number (Mg/Mg+Fe+Mn+Ca). Raman shifts calibrated as a function of Mg number were used in turn to evaluate the chemical composition of natural carbonate samples. In particular it is shown that detailed micron-resolution Raman maps can be generated of carbonate crystal-zonation in hydrothermally altered sedimentary deposits from Archean greenstone belts. Large spectral-range analysis (140-2000 cm-1) in static-mode (centered at 1150 cm-1) allows for combined Raman mapping of both carbonate-composition (2ν2, T, L modes) as well as kerogen structural ordering (D1-D4 and G modes in the range 1100-1700 cm-1), and therefore allows for simultaneous characterization of putative organic microfossils and associated carbonate matrix in metamorphosed Archean rock samples. Finally, it will be shown that these carbonate solid solutions can be distinguished from other end-member carbonates such as calcite, vaterite and the orthorhombic polymorph aragonite.

MAVEN SupraThermal and Thermal Ion Compostion (STATIC) Instrument

NASA Astrophysics Data System (ADS)

McFadden, J. P.; Kortmann, O.; Curtis, D.; Dalton, G.; Johnson, G.; Abiad, R.; Sterling, R.; Hatch, K.; Berg, P.; Tiu, C.; Gordon, D.; Heavner, S.; Robinson, M.; Marckwordt, M.; Lin, R.; Jakosky, B.

2015-12-01

The MAVEN SupraThermal And Thermal Ion Compostion (STATIC) instrument is designed to measure the ion composition and distribution function of the cold Martian ionosphere, the heated suprathermal tail of this plasma in the upper ionosphere, and the pickup ions accelerated by solar wind electric fields. STATIC operates over an energy range of 0.1 eV up to 30 keV, with a base time resolution of 4 seconds. The instrument consists of a toroidal "top hat" electrostatic analyzer with a 360° × 90° field-of-view, combined with a time-of-flight (TOF) velocity analyzer with 22.5° resolution in the detection plane. The TOF combines a -15 kV acceleration voltage with ultra-thin carbon foils to resolve H+, He^{++}, He+, O+, O2+, and CO2+ ions. Secondary electrons from carbon foils are detected by microchannel plate detectors and binned into a variety of data products with varying energy, mass, angle, and time resolution. To prevent detector saturation when measuring cold ram ions at periapsis (˜10^{1 1} eV/cm2 s sr eV), while maintaining adequate sensitivity to resolve tenuous pickup ions at apoapsis (˜103 eV/cm2 s sr eV), the sensor includes both mechanical and electrostatic attenuators that increase the dynamic range by a factor of 103. This paper describes the instrument hardware, including several innovative improvements over previous TOF sensors, the ground calibrations of the sensor, the data products generated by the experiment, and some early measurements during cruise phase to Mars.

Rovibrational study of the 2ν2 band of D213CO by high-resolution Fourier transform infrared spectroscopy

NASA Astrophysics Data System (ADS)

Wu, Q. Y.; Tan, T. L.; A'dawiah, Rabia'tul; Ng, L. L.

2018-03-01

The high-resolution FTIR spectrum of the 2ν2 band (3250-3380 cm-1) of D213CO was recorded at an unapodized resolution of 0.0063 cm-1. A total of 747 rovibrational transitions have been assigned and fitted up to J″ = 32 and Ka″ = 10 using the Watson's A-reduced Hamiltonian in the Ir representation. A set of accurate upper state (v2 = 2) rovibrational constants, three rotational and five quartic centrifugal distortion constants, were determined for the first time. The band center of the 2ν2 band was found to be 3326.765109 ± 0.000079 cm-1. The rms deviation of the rovibrational fit was 0.00096 cm-1.

Atmospheric Sounder Spectrometer for Infrared Spectral Technology (ASSIST) Instrument Handbook

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

Flynn, Connor J.

The Atmospheric Sounder Spectrometer for Infrared Spectral Technology (ASSIST) measures the absolute infrared (IR) spectral radiance (watts per square meter per steradian per wavenumber) of the sky directly above the instrument. More information about the instrument can be found through the manufacturer’s website. The spectral measurement range of the instrument is 3300 to 520 wavenumbers (cm -1) or 3-19.2 microns for the normal-range instruments and 3300 to 400 cm -1 or 3-25 microns, for the extended-range polar instruments. Spectral resolution is 1.0 cm -1. Instrument field-of-view is 1.3 degrees. Calibrated sky radiance spectra are produced on cycle of about 141more » seconds with a group of 6 radiance spectra zenith having dwell times of about 14 seconds each interspersed with 55 seconds of calibration and mirror motion. The ASSIST data is comparable to the Atmospheric Emitted Radiance Interferometer (AERI) data and can be used for 1) evaluating line-by-line radiative transport codes, 2) detecting/quantifying cloud effects on ground-based measurements of infrared spectral radiance (and hence is valuable for cloud property retrievals), and 3) calculating vertical atmospheric profiles of temperature and water vapor and the detection of trace gases.« less

Coherent Doppler lidar for automated space vehicle rendezvous, stationkeeping and capture

NASA Technical Reports Server (NTRS)

Bilbro, James A.

1991-01-01

The inherent spatial resolution of laser radar makes ladar or lidar an attractive candidate for Automated Rendezvous and Capture application. Previous applications were based on incoherent lidar techniques, requiring retro-reflectors on the target vehicle. Technology improvements (reduced size, no cryogenic cooling requirement) have greatly enhanced the construction of coherent lidar systems. Coherent lidar permits the acquisition of non-cooperative targets at ranges that are limited by the detection capability rather than by the signal-to-noise ratio (SNR) requirements. The sensor can provide translational state information (range, velocity, and angle) by direct measurement and, when used with any array detector, also can provide attitude information by Doppler imaging techniques. Identification of the target is accomplished by scanning with a high pulse repetition frequency (dependent on the SNR). The system performance is independent of range and should not be constrained by sun angle. An initial effort to characterize a multi-element detection system has resulted in a system that is expected to work to a minimum range of 1 meter. The system size, weight and power requirements are dependent on the operating range; 10 km range requires a diameter of 3 centimeters with overall size at 3 x 3 x 15 to 30 cm, while 100 km range requires a 30 cm diameter.

The small-animal radiation research platform (SARRP): dosimetry of a focused lens system.

PubMed

Deng, Hua; Kennedy, Christopher W; Armour, Elwood; Tryggestad, Erik; Ford, Eric; McNutt, Todd; Jiang, Licai; Wong, John

2007-05-21

A small animal radiation platform equipped with on-board cone-beam CT and conformal irradiation capabilities is being constructed for translational research. To achieve highly localized dose delivery, an x-ray lens is used to focus the broad beam from a 225 kVp x-ray tube down to a beam with a full width half maximum (FWHM) of approximately 1.5 mm in the energy range 40-80 keV. Here, we report on the dosimetric characteristics of the focused beam from the x-ray lens subsystem for high-resolution dose delivery. Using the metric of the average dose within a 1.5 mm diameter area, the dose rates at a source-to-surface distance (SSD) of 34 cm are 259 and 172 cGy min(-1) at 6 mm and 2 cm depths, respectively, with an estimated uncertainty of +/-5%. The per cent depth dose is approximately 56% at 2 cm depth for a beam at 34 cm SSD.

Ultra-high resolution four dimensional geodetic imaging of engineered structures for stability assessment

USGS Publications Warehouse

Bawden, Gerald W.; Bond, Sandra; Podoski, J. H.; Kreylos, O.; Kellogg, L. H.

2012-01-01

We used ground-based Tripod LiDAR (T-LiDAR) to assess the stability of two engineered structures: a bridge spanning the San Andreas fault following the M6.0 Parkfield earthquake in Central California and a newly built coastal breakwater located at the Kaumālapa`u Harbor Lana'i, Hawaii. In the 10 weeks following the earthquake, we found that the surface under the bridge shifted 7.1 cm with an additional 2.6 cm of motion in the subsequent 13 weeks, which deflected the bridge's northern I-beam support 4.3 cm and 2.1 respectively; the bridge integrity remained intact. T-LiDAR imagery was collected after the completion of armored breakwater with 817 35-ton interlocking concrete armor units, Core-Locs®, in the summers of 2007, 2008 and 2010. We found a wide range of motion of individual Core-Locs, from a few centimeters to >110 cm along the ocean side of the breakwater, with lesser movement along the harbor side.

Infrared spectroscopy of dense clouds in the C-H stretch region - Methanol and 'diamonds'

NASA Technical Reports Server (NTRS)

Allamandola, L. J.; Sandford, S. A.; Tielens, A. G. G. M.; Herbst, T. M.

1992-01-01

The paper presents high spectral resolution studies in the 3100-2600/cm range of the protostars NGC 7538 IRS9, W33A, W3 IRS 5, and S140 IRS 1. Well-resolved absorption bands at about 2825/cm and 2880/cm were found superposed on the LF wing of the strong O-H stretch feature. The 2880/cm band, previously detected toward W33A, is also in the spectrum of NGC 7538 IRS 9. The relative strength of these two bands varies, showing that they are associated with two different carriers. The new band at about 2880/cm falls near the position of C-H stretching vibrations in tertiary carbon atoms. The strength of this feature, in combination with the lack of strong features associated with primary and secondary carbon atoms, suggests that the carrier of the new feature has a diamondlike structure. This new feature is tentatively attributed to interstellar 'diamonds'. The detection of this band in the spectra of all four dense molecular clouds suggests that the carrier is ubiquitous in dense clouds.

Calibration of the COBE FIRAS instrument

NASA Technical Reports Server (NTRS)

Fixsen, D. J.; Cheng, E. S.; Cottingham, D. A.; Eplee, R. E., Jr.; Hewagama, T.; Isaacman, R. B.; Jensen, K. A.; Mather, J. C.; Massa, D. L.; Meyer, S. S.

1994-01-01

The Far-Infrared Absolute Spectrophotometer (FIRAS) instrument on the Cosmic Background Explorer (COBE) satellite was designed to accurately measure the spectrum of the cosmic microwave background radiation (CMBR) in the frequency range 1-95/cm with an angular resolution of 7 deg. We describe the calibration of this instrument, including the method of obtaining calibration data, reduction of data, the instrument model, fitting the model to the calibration data, and application of the resulting model solution to sky observations. The instrument model fits well for calibration data that resemble sky condition. The method of propagating detector noise through the calibration process to yield a covariance matrix of the calibrated sky data is described. The final uncertainties are variable both in frequency and position, but for a typical calibrated sky 2.6 deg square pixel and 0.7/cm spectral element the random detector noise limit is of order of a few times 10(exp -7) ergs/sq cm/s/sr cm for 2-20/cm, and the difference between the sky and the best-fit cosmic blackbody can be measured with a gain uncertainty of less than 3%.

The spatial distribution of soil organic carbon in tidal wetland soils of the continental United States.

PubMed

Hinson, Audra L; Feagin, Rusty A; Eriksson, Marian; Najjar, Raymond G; Herrmann, Maria; Bianchi, Thomas S; Kemp, Michael; Hutchings, Jack A; Crooks, Steve; Boutton, Thomas

2017-12-01

Tidal wetlands contain large reservoirs of carbon in their soils and can sequester carbon dioxide (CO 2 ) at a greater rate per unit area than nearly any other ecosystem. The spatial distribution of this carbon influences climate and wetland policy. To assist with international accords such as the Paris Climate Agreement, national-level assessments such as the United States (U.S.) National Greenhouse Gas Inventory, and regional, state, local, and project-level evaluation of CO 2 sequestration credits, we developed a geodatabase (CoBluCarb) and high-resolution maps of soil organic carbon (SOC) distribution by linking National Wetlands Inventory data with the U.S. Soil Survey Geographic Database. For over 600,000 wetlands, the total carbon stock and organic carbon density was calculated at 5-cm vertical resolution from 0 to 300 cm of depth. Across the continental United States, there are 1,153-1,359 Tg of SOC in the upper 0-100 cm of soils across a total of 24 945.9 km 2 of tidal wetland area, twice as much carbon as the most recent national estimate. Approximately 75% of this carbon was found in estuarine emergent wetlands with freshwater tidal wetlands holding about 19%. The greatest pool of SOC was found within the Atchafalaya/Vermilion Bay complex in Louisiana, containing about 10% of the U.S. total. The average density across all tidal wetlands was 0.071 g cm -3 across 0-15 cm, 0.055 g cm -3 across 0-100 cm, and 0.040 g cm -3 at the 100 cm depth. There is inherent variability between and within individual wetlands; however, we conclude that it is possible to use standardized values at a range of 0-100 cm of the soil profile, to provide first-order quantification and to evaluate future changes in carbon stocks in response to environmental perturbations. This Tier 2-oriented carbon stock assessment provides a scientific method that can be copied by other nations in support of international requirements. © 2017 John Wiley & Sons Ltd.

Cyclops: single-pixel imaging lidar system based on compressive sensing

NASA Astrophysics Data System (ADS)

Magalhães, F.; Correia, M. V.; Farahi, F.; Pereira do Carmo, J.; Araújo, F. M.

2017-11-01

Mars and the Moon are envisaged as major destinations of future space exploration missions in the upcoming decades. Imaging LIDARs are seen as a key enabling technology in the support of autonomous guidance, navigation and control operations, as they can provide very accurate, wide range, high-resolution distance measurements as required for the exploration missions. Imaging LIDARs can be used at critical stages of these exploration missions, such as descent and selection of safe landing sites, rendezvous and docking manoeuvres, or robotic surface navigation and exploration. Despite these devices have been commercially available and used for long in diverse metrology and ranging applications, their size, mass and power consumption are still far from being suitable and attractive for space exploratory missions. Here, we describe a compact Single-Pixel Imaging LIDAR System that is based on a compressive sensing technique. The application of the compressive codes to a DMD array enables compression of the spatial information, while the collection of timing histograms correlated to the pulsed laser source ensures image reconstruction at the ranged distances. Single-pixel cameras have been compared with raster scanning and array based counterparts in terms of noise performance, and proved to be superior. Since a single photodetector is used, a better SNR and higher reliability is expected in contrast with systems using large format photodetector arrays. Furthermore, the event of failure of one or more micromirror elements in the DMD does not prevent full reconstruction of the images. This brings additional robustness to the proposed 3D imaging LIDAR. The prototype that was implemented has three modes of operation. Range Finder: outputs the average distance between the system and the area of the target under illumination; Attitude Meter: provides the slope of the target surface based on distance measurements in three areas of the target; 3D Imager: produces 3D ranged images of the target surface. The implemented prototype demonstrated a frame rate of 30 mHz for 16x16 pixels images, a transversal (xy) resolution of 2 cm at 10 m for images with 64x64 pixels and the range (z) resolution proved to be better than 1 cm. The experimental results obtained for the "3D imaging" mode of operation demonstrated that it was possible to reconstruct spherical smooth surfaces. The proposed solution demonstrates a great potential for: miniaturization; increase spatial resolution without using large format detector arrays; eliminate the need for scanning mechanisms; implementing simple and robust configurations.

Miniature Fourier transform spectrometer with a dual closed-loop controlled electrothermal micromirror.

PubMed

Han, Fengtian; Wang, Wei; Zhang, Xiaoyang; Xie, Huikai

2016-10-03

A large piston-displacement electrothermal micromirror with closed-loop control of both piston scan and tilting of the mirror plate is demonstrated for use in a miniature Fourier transform spectrometer. Constant scan velocity in an ultra large piston scan range has been demonstrated by the proposed closed-loop piston control scheme which can be easily implemented without considerably increasing system complexity. The experimental results show that the usable linear scan range generated by the micromirror has been extended up to 505 μm. The measured spectral resolution in a compact spectrometer reaches 20 cm^-1, or 0.57 nm at 532 nm wavelength. Compared to other presented systems, this microspectrometer will benefit from the closed-loop thermal actuator approach utilizing both the piston servo and tilt control to provide more consistent spectral response, improved spectral resolution and enhanced robustness to disturbances.

Chaotic optical time-domain reflectometry using a distributed feedback laser diode modulated by an improved Colpitts oscillator

NASA Astrophysics Data System (ADS)

Li, Jing Xia; Xu, Hang; Liu, Li; Su, Peng Cheng; Zhang, Jian Guo

2015-05-01

We report a chaotic optical time-domain reflectometry for fiber fault location, where a chaotic probe signal is generated by driving a distributed feedback laser diode with an improved Colpitts chaotic oscillator. The results show that the unterminated fiber end, the loose connector, and the mismatch connector can be precisely located. A measurement range of approximately 91 km and a range independent resolution of 6 cm are achieved. This implementation method is easy to integrate and is cost effective, which gives it great potential for commercial applications.

Multiplexing curvature sensors using fibre segment interferometry for lateral vibration measurements

NASA Astrophysics Data System (ADS)

Kissinger, Thomas; Chehura, Edmon; James, Stephen W.; Tatam, Ralph P.

2017-04-01

Dynamic fibre-optic curvature sensing is demonstrated by interrogating chains of fibre segments, separated by broadband Bragg grating reflectors, using range-resolved interferometry (RRI). Four fibre strings, containing four fibre segments each of gauge length 20 cm, are attached to the opposing sides of a support structure and the resulting differential strain measurements allow inference of lateral displacements of a cantilever test object. Dynamic tip displacement resolutions in the micrometre range at an interferometric bandwidth of 21 kHz demonstrate the suitability of this approach for highly sensitive and cost-effective fibre-optic directional vibration measurements of smart structures.

NDSD-1000: High-resolution, high-temperature Nitrogen Dioxide Spectroscopic Databank

NASA Astrophysics Data System (ADS)

Lukashevskaya, A. A.; Lavrentieva, N. N.; Dudaryonok, A. C.; Perevalov, V. I.

2016-11-01

We present a high-resolution, high-temperature version of the Nitrogen Dioxide Spectroscopic Databank called NDSD-1000. The databank contains the line parameters (positions, intensities, self- and air-broadening coefficients, exponents of the temperature dependence of self- and air-broadening coefficients) of the principal isotopologue of NO2. The reference temperature for line intensity is 296 K and the intensity cutoff is 10-25 cm-1/molecule cm-2 at 1000 K. The broadening parameters are presented for two reference temperatures 296 K and 1000 K. The databank has 1,046,808 entries, covers five spectral regions in the 466-4776 cm-1 spectral range and is designed for temperatures up to 1000 K. The databank is based on the global modeling of the line positions and intensities performed within the framework of the method of effective operators. The parameters of the effective Hamiltonian and the effective dipole moment operator have been fitted to the observed values of the line positions and intensities collected from the literature. The broadening coefficients as well as the temperature exponents are calculated using the semi-empirical approach. The databank is useful for studying high-temperature radiative properties of NO2. NDSD-1000 is freely accessible via the internet site of V.E. Zuev Institute of Atmospheric Optics SB RAS ftp://ftp.iao.ru/pub/NDSD/.

ASD-1000: High-resolution, high-temperature acetylene spectroscopic databank

NASA Astrophysics Data System (ADS)

Lyulin, O. M.; Perevalov, V. I.

2017-11-01

We present a high-resolution, high-temperature version of the Acetylene Spectroscopic Databank called ASD-1000. The databank contains the line parameters (position, intensity, Einstein coefficient for spontaneous emission, term value of the lower states, self- and air-broadening coefficients, temperature dependence exponents of the self- and air-broadening coefficients) of the principal isotopologue of C2H2. The reference temperature for line intensity is 296 K and the intensity cutoff is 10-27 cm-1/(molecule cm-2) at 1000 K. The databank has 33,890,981 entries and covers the 3-10,000 cm-1 spectral range. The databank is based on the global modeling of the line positions and intensities performed within the framework of the method of effective operators. The parameters of the effective Hamiltonian and the effective dipole moment operator have been fitted to the observed values of the line positions and intensities collected from the literature. The broadening coefficients as well as their temperature dependence exponents were calculated using the empirical equations. The databank is useful for studying high-temperature radiative properties of C2H2. ASD-1000 is freely accessible via the Internet site of V.E. Zuev Institute of Atmospheric Optics SB RAS ftp://ftp.iao.ru/pub/ASD1000/.

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

NASA Astrophysics Data System (ADS)

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

2014-09-01

Microchannel plate (MCP) based imaging, photon time tagging detector sealed tube schemes have a unique set of operational features that enable high time resolution astronomical and remote sensing applications to be addressed. New detectors using the cross strip (XS), cross delay line (XDL), or stripline anode readouts, a wide range of photocathode types, and advanced MCP technologies have been implemented to improve many performance characteristics. A variety of sealed tubes have been developed including 18mm XS readout devices with GaAs and SuperGenII photocathodes, 25mm XDL readout devices with SuperGenII and GaN photocathodes, and 20 x 20 cm sealed tubes with bialkali photocathodes and strip line readout. One key technology that has just become viable is the ability to make MCPs using atomic layer deposition (ALD) techniques. This employs nanofabrication of the active layers of an MCP on a microcapillary array. This technique opens new performance opportunities, including, very large MCP areas (>20cm), very low intrinsic background, lower radiation induced background, much longer overall lifetime and gain stability, and markedly lower outgassing which can improve the sealed tube lifetime and ease of fabrication. The XS readout has been implemented in formats of 22mm, 50mm and 100mm, and uses MCP charge signals detected on two orthogonal layers of conductive fingers to encode event X-Y positions. We have achieved spatial resolution XS detectors better than 25 microns FWHM, with good image linearity while at low gain (<10^6), substantially increasing local counting rate capabilities and the overall tube lifetime. XS tubes with updated electronics can encode event rates of >5 MHz with ~12% dead time and event timing accuracy of ~100ps. XDL sealed tubes in 25mm format demonstrate ~40 micron spatial resolution at up to ~2 MHz event rates, and have been developed with SupergenII visible regime photocathodes. The XDL tubes also achieve ~100 ps time resolution. Most recently ALD MCPs with an opaque GaN photocathode (100-350nm range) on the MCP surface has been demonstrated in a sealed tube configuration. These ALD MCPs show a stable and permanent 10x gain increase during tube processing. Efforts are also underway to establish ALD MCP configurations with large area sealed tubes from 5cm up to 20cm in size. We will discuss these efforts and their performance characteristics. We will discuss how we are applying these detector system developments to a number of applications. This includes ground based instruments for observations of transient and variable astronomical objects, as well as implementation in satellite instruments for earth atmospheric and solar observations. The XS 18mm sealed tube detectors are being implemented for night time remote reconnaissance and biological single-molecule fluorescence lifetime imaging microscopy. Related efforts also include development of large (20cm) sealed tubes for Cherenkov light detection and large area focal plane imagers, and GaN sealed tube devices are candidates for future astronomical space based UV imaging and spectroscopy.

Measuring orthometric water heights from lightweight Unmanned Aerial Vehicles (UAVs)

NASA Astrophysics Data System (ADS)

Bandini, Filippo; Olesen, Daniel; Jakobsen, Jakob; Reyna-Gutierrez, Jose Antonio; Bauer-Gottwein, Peter

2016-04-01

A better quantitative understanding of hydrologic processes requires better observations of hydrological variables, such as surface water area, water surface level, its slope and its temporal change. However, ground-based measurements of water heights are restricted to the in-situ measuring stations. Hence, the objective of remote sensing hydrology is to retrieve these hydraulic variables from spaceborne and airborne platforms. The forthcoming Surface Water and Ocean Topography (SWOT) satellite mission will be able to acquire water heights with an expected accuracy of 10 centimeters for rivers that are at least 100 m wide. Nevertheless, spaceborne missions will always face the limitations of: i) a low spatial resolution which makes it difficult to separate water from interfering surrounding areas and a tracking of the terrestrial water bodies not able to detect water heights in small rivers or lakes; ii) a limited temporal resolution which limits the ability to determine rapid temporal changes, especially during extremes. Unmanned Aerial Vehicles (UAVs) are one technology able to fill the gap between spaceborne and ground-based observations, ensuring 1) high spatial resolution; 2) tracking of the water bodies better than any satellite technology; 3) timing of the sampling which only depends on the operator 4) flexibility of the payload. Hence, this study focused on categorizing and testing sensors capable of measuring the range between the UAV and the water surface. The orthometric height of the water surface is then retrieved by subtracting the height above water measured by the sensors from the altitude above sea level retrieved by the onboard GPS. The following sensors were tested: a) a radar, b) a sonar c) a laser digital-camera based prototype developed at Technical University of Denmark. The tested sensors comply with the weight constraint of small UAVs (around 1.5 kg). The sensors were evaluated in terms of accuracy, maximum ranging distance and beam divergence. The sonar demonstrated a maximum ranging distance of 10 m, the laser prototype of 15 m, whilst the radar is potentially able to measure the range to water surface from a height up to 50 m. After numerous test flights above a lake with an approximately horizontal water surface, estimation of orthometric water height error, including overall accuracy of the system GPS-sensors, was possible. The RTK GPS system proved able to deliver a relative vertical accuracy better than 5-7 cm. The radar confirmed to have the best reliability with an accuracy which is generally few cm (0.7-1.3% of the ranging distance). Whereas the accuracy of the sonar and laser varies from few cm (0.7-1.6% of the ranging distance) to some tens of cm because sonar measurements are generally influenced by noise and turbulence generated by the propellers of the UAV and the laser prototype is affected by drone vibrations and water waviness. However, the laser prototype demonstrated the lowest beam divergence, which is required to measure unconventional remote sensing targets, such as sinkholes and Mexican cenotes, and to clearly distinguish between rivers and interfering surroundings, such as riparian vegetation.

Change detection using 75-year aerial photo and satellite data sets, inexpensive means to obtain 6 cm resolution data, and developing opportunities for community-oriented remote sensing through photography

USDA-ARS?s Scientific Manuscript database

Some governmental research sites have been in existence for as many as 100 years with ground photography used for documentation starting in the early 1900s(e.g., at the USDA Jornada Experimental Range(JER)(783 km2) in south central New Mexico) If ground photography is properly documented when acquir...

Quasi-simultaneous in-line flue gas monitoring of NO and NO₂ emissions at a caloric power plant employing mid-IR laser spectroscopy.

PubMed

Reidl-Leuthner, Christoph; Viernstein, Alexander; Wieland, Karin; Tomischko, Wolfgang; Sass, Ludwig; Kinger, Gerald; Ofner, Johannes; Lendl, Bernhard

2014-09-16

Two pulsed thermoelectrically cooled mid-infrared distributed feedback quantum cascade lasers (QCLs) were used for the quasi-simultaneous in-line determination of NO and NO2 at the caloric power plant Dürnrohr (Austria). The QCL beams were combined using a bifurcated hollow fiber, sent through the flue tube (inside diameter: 5.5 m), reflected by a retro-reflector and recorded using a fast thermoelectrically cooled mercury-cadmium-telluride detector. The thermal chirp during 300 ns pulses was about 1.2 cm(-1) and allowed scanning of rotational vibrational doublets of the analytes. On the basis of the thermal chirp and the temporal resolution of data acquisition, a spectral resolution of approximately 0.02 cm(-1) was achieved. The recorded rotational vibrational absorption lines were centered at 1900 cm(-1) for NO and 1630 cm(-1) for NO2. Despite water content in the range of 152-235 g/m(3) and an average particle load of 15.8 mg/m(3) in the flue gas, in-line measurements were possible achieving limits of detection of 73 ppb for NO and 91 ppb for NO2 while optimizing for a single analyte. Quasi-simultaneous measurements resulted in limits of detection of 219 ppb for NO and 164 ppb for NO2, respectively. Influences of temperature and pressure on the data evaluation are discussed, and results are compared to an established reference method based on the extractive measurements presented.

Quantification of HCl from high-resolution, ground-based, infrared solar spectra in the 3000 per cm region

NASA Technical Reports Server (NTRS)

Goldman, A.; Murcray, F. J.; Blatherwick, R. D.; Murcray, D. G.

1986-01-01

Recent ground-based infrared solar spectra at 0.02 per cm resolution in the 3000 per cm region have been analyzed for the atmospheric content of HCl. Nonlinear spectral least-squares fitting applied to spectra obtained at several zenith angles shows little sensitivity of the results to tropospheric HCl but provides an accurate measurement of the total column amount.

FIFI: The MPE Garching/UC Berkeley Far-Infrared Imaging Fabry-Perot Interferometer

NASA Technical Reports Server (NTRS)

Geis, Norbert; Genzel, Reinhard; Haggerty, M.; Herrmann, F.; Jackson, J.; Madden, Suzanne C.; Nikola, T.; Poglitsch, Albrecht; Rumitz, M.; Stacey, G. J.

1995-01-01

We describe the performance characteristics of the MPE Garching/UC Berkeley Far-Infrared Imaging Fabry-Perot Interferometer (FIFI) for the Kuiper Airborne Observatory (KAO). The spectrometer features two or three cryogenic tunable Fabry-Perot filters in series giving spectral resolution R of up to 10(exp 5) in the range of 40 microns less than lambda less than 200 microns, and an imaging 5x5 array of photoconductive detectors with variable focal plane plate scale. The instrument works at background limited sensitivity of up to 2 x 10(exp -19) W cm(exp -2) Hz(exp -1/2) per pixel per resolution element at R = 10(exp 5) on the KAO.

Directional measurement of short ocean waves with stereophotography

NASA Technical Reports Server (NTRS)

Shemdin, Omar H.; Tran, H. Minh; Wu, S. C.

1988-01-01

Stereophotographs of the sea surface, acquired during the Tower Ocean Wave and Radar Dependence experiment are analyzed to yield directional wave height spectra of short surface waves in the 6-80-cm range. The omnidirectional wave height spectra are found to deviate from the k exp -4 distribution, where k is the wave number. The stereo data processing errors are found to be within + or - 5 percent. The omnidirectional spectra yield 514 deg of freedom for 30-cm-long waves. The directional distribution of short waves is processed with a directional resolution of 30 deg, so as to yield 72 deg of freedom for 30-cm-long waves. The directional distributions show peaks that are aligned with the wind and swell directions. It is found that dynamically relevant measurements can be obtained with stereophotography, after removal of the mean surface associated with long waves.

Lava flow topographic measurements for radar data interpretation

NASA Technical Reports Server (NTRS)

Campbell, Bruce A.; Garvin, James B.

1993-01-01

Topographic profiles at 25- and 5-cm horizontal resolution for three sites along a lava flow on Kilauea Volcano are presented, and these data are used to illustrate techniques for surface roughness analysis. Height and slope distributions and the height autocorrelation function are evaluated as a function of varying lowpass filter wavelength for the 25-cm data. Rms slopes are found to increase rapidly with decreasing topographic scale and are typically much higher than those found by modeling of Magellan altimeter data for Venus. A more robust description of the surface roughness appears to be the ratio of rms height to surface height correlation length. For all three sites this parameter falls within the range of values typically found from model fits to Magellan altimeter waveforms. The 5-cm profile data are used to estimate the effect of small-scale roughness on quasi-specular scattering.

Investigating the structure and fragmentation of a highly filamentary IRDC

NASA Astrophysics Data System (ADS)

Henshaw, J. D.; Caselli, P.; Fontani, F.; Jiménez-Serra, I.; Tan, J. C.; Longmore, S. N.; Pineda, J. E.; Parker, R. J.; Barnes, A. T.

2016-11-01

We present 3.7 arcsec (˜0.05 pc) resolution 3.2 mm dust continuum observations from the Institut de Radioastronomie Millimétrique Plateau de Bure Interferometer, with the aim of studying the structure and fragmentation of the filamentary infrared dark cloud (IRDC) G035.39-00.33. The continuum emission is segmented into a series of 13 quasi-regularly spaced (λobs ˜ 0.18 pc) cores, following the major axis of the IRDC. We compare the spatial distribution of the cores with that predicted by theoretical work describing the fragmentation of hydrodynamic fluid cylinders, finding a significant (a factor of ≳ 8) discrepancy between the two. Our observations are consistent with the picture emerging from kinematic studies of molecular clouds suggesting that the cores are harboured within a complex network of independent sub-filaments. This result emphasizes the importance of considering the underlying physical structure, and potentially, dynamically important magnetic fields, in any fragmentation analysis. The identified cores exhibit a range in (peak) beam-averaged column density (3.6 × 1023 cm-2 < NH, c < 8.0 × 1023 cm-2), mass (8.1 M⊙ < Mc < 26.1 M⊙), and number density (6.1 × 105 cm-3 < nH, c, eq < 14.7 × 105 cm-3). Two of these cores, dark in the mid-infrared, centrally concentrated, monolithic (with no traceable substructure at our PdBI resolution), and with estimated masses of the order ˜20-25 M⊙, are good candidates for the progenitors of intermediate-to-high-mass stars. Virial parameters span a range 0.2 < αvir < 1.3. Without additional support, possibly from dynamically important magnetic fields with strengths of the order of 230 μG < B < 670 μG, the cores are susceptible to gravitational collapse. These results may imply a multilayered fragmentation process, which incorporates the formation of sub-filaments, embedded cores, and the possibility of further fragmentation.

Design of Oil Viscosity Sensor Based on Plastic Optical Fiber

NASA Astrophysics Data System (ADS)

Yunus, Muhammad; Arifin, A.

2018-03-01

A research of plastic optical fiber based sensors have been studied for measurement of oil viscosity. This sensor was made with straight configuration, U configuration, and gamma configuration have two types, there are optical fiber sensor with cladding and without cladding. Viscosity sensor was made, dipped into an oil sample with a concentration of viscosity percentage about 270 mPa.s - 350 mPa.s. The light from the LED propagated into the optical fiber, then it was received by the photodetector converted to output power. When plastic optical fiber dipped into an oil sample, viscosity of oil affect increase of refractive index on optical fiber resulting in a bigger loss of power so the light intensity will be smaller, consequences the measured output power will be smaller. Sensitivity and resolution viscosity sensor without cladding peel showed the best result rather than viscosity sensor with cladding peel. The best result in the measurement showed in gamma configuration with 3 cm length of cladding peel and the diameter of bending 0,25 cm is the range 103,090 nWatt, sensitivity 1,289 nWatt/mPa.s, and resolution 0,776 mPa.s. This method is effectively and efficiently used as an oil viscosity sensor with high sensitivity and resolution.

Turbulence imaging and applications using beam emission spectroscopy on DIII-D (invited)

NASA Astrophysics Data System (ADS)

McKee, G. R.; Fenzi, C.; Fonck, R. J.; Jakubowski, M.

2003-03-01

Two-dimensional measurements of density fluctuations are obtained in the radial and poloidal plane of the DIII-D tokamak with the Beam Emission Spectroscopy (BES) diagnostic system. The goals are to visualize the spatial structure and time evolution of turbulent eddies, as well as to obtain the 2D statistical properties of turbulence. The measurements are obtained with an array of localized BES spatial channels configured to image a midplane region of the plasma. 32 channels have been deployed, each with a spatial resolution of about 1 cm in the radial and poloidal directions, thus providing measurements of turbulence in the wave number range 0

Microdosimetric measurements of a clinical proton beam with micrometer-sized solid-state detector.

PubMed

Anderson, Sarah E; Furutani, Keith M; Tran, Linh T; Chartier, Lachlan; Petasecca, Marco; Lerch, Michael; Prokopovich, Dale A; Reinhard, Mark; Perevertaylo, Vladimir L; Rosenfeld, Anatoly B; Herman, Michael G; Beltran, Chris

2017-11-01

Microdosimetry is a vital tool for assessing the microscopic patterns of energy deposition by radiation, which ultimately govern biological effect. Solid-state, silicon-on-insulator microdosimeters offer an approach for making microdosimetric measurements with high spatial resolution (on the order of tens of micrometers). These high-resolution, solid-state microdosimeters may therefore play a useful role in characterizing proton radiotherapy fields, particularly for making highly resolved measurements within the Bragg peak region. In this work, we obtain microdosimetric measurements with a solid-state microdosimeter (MicroPlus probe) in a clinical, spot-scanning proton beam of small spot size. The MicroPlus probe had a 3D single sensitive volume on top of silicon oxide. The sensitive volume had an active cross-sectional area of 250 μm × 10 μm and thickness of 10 μm. The proton facility was a synchrotron-based, spot-scanning system with small spot size (σ ≈ 2 mm). We performed measurements with the clinical beam current (≈1 nA) and had no detected pulse pile-up. Measurements were made in a water-equivalent phantom in water-equivalent depth (WED) increments of 0.25 mm or 1.0 mm along pristine Bragg peaks of energies 71.3 MeV and 159.9 MeV, respectively. For each depth, we measured lineal energy distributions and then calculated the dose-weighted mean lineal energy, y¯D. The measurements were repeated for two field sizes: 4 × 4 cm 2 and 20 × 20 cm 2 . For both 71.3 MeV and 159.9 MeV and for both field sizes, y¯D increased with depth toward the distal edge of the Bragg peak, a result consistent with Monte Carlo calculations and measurements performed elsewhere. For the 71.3 MeV, 4 × 4 cm 2 beam (range at 80% distal falloff, R 80  = 3.99 cm), we measured y¯D=1.96±0.08 keV/μm at WED = 2 cm, and y¯D=10.6±0.32 keV/μm at WED = 3.95 cm. For the 71.3 MeV, 20 × 20 cm 2 beam, we measured y¯D=2.46±0.12 keV/μm at WED = 2.6 cm, and y¯D=11.0±0.24 keV/μm at WED = 3 cm. For the 159.9 MeV, 4 × 4 cm 2 beam (R 80  = 17.7 cm), y¯D=2.24±0.15 keV/μm at WED = 5 cm, and y¯D=8.99±0.71 keV/μm at WED = 17.6 cm. For the 159.9 MeV, 20 × 20 cm 2 beam, y¯D=2.56±0.10 keV/μm at WED = 5 cm, and y¯D=9.24±0.73 keV/μm at WED = 17.6 cm. We performed microdosimetric measurements with a novel solid-state, silicon-on-insulator microdosimeter in a clinical spot-scanning proton beam of small spot size and unmodified beam current. For all of the proton field sizes and energies considered, the measurements of y¯D were in agreement with expected trends. Furthermore, we obtained measurements with a spatial resolution of 10 μm in the beam direction. This spatial resolution greatly exceeded that possible with a conventional gaseous tissue-equivalent proportional counter and allowed us to perform a high-resolution investigation within the Bragg peak region. The MicroPlus probe is therefore suitable for applications in proton radiotherapy. © 2017 American Association of Physicists in Medicine.

A 2D silicon detector array for quality assurance in small field dosimetry: DUO.

PubMed

Shukaili, Khalsa Al; Petasecca, Marco; Newall, Matthew; Espinoza, Anthony; Perevertaylo, Vladimir L; Corde, Stéphanie; Lerch, Michael; Rosenfeld, Anatoly B

2017-02-01

Nowadays, there are many different applications that use small fields in radiotherapy treatments. The dosimetry of small radiation fields is not trivial due to the problems associated with lateral disequilibrium and source occlusion and requires reliable quality assurance (QA). Ideally such a QA tool should provide high spatial resolution, minimal beam perturbation and real time fast measurements. Many different types of silicon diode arrays are used for QA in radiotherapy; however, their application in small filed dosimetry is limited, in part, due to a lack of spatial resolution. The Center of Medical Radiation Physics (CMRP) has developed a new generation of a monolithic silicon diode array detector that will be useful for small field dosimetry in SRS/SRT. The objective of this study is to characterize a monolithic silicon diode array designed for dosimetry QA in SRS/SRT named DUO that is arranged as two orthogonal 1D arrays with 0.2 mm pitch. DUO is two orthogonal 1D silicon detector arrays in a monolithic crystal. Each orthogonal array contains 253 small pixels with size 0.04 × 0.8 mm 2 and three central pixels are with a size of 0.18 × 0.18 mm 2 each. The detector pitch is 0.2 mm and total active area is 52 × 52 mm 2 . The response of the DUO silicon detector was characterized in terms of dose per pulse, percentage depth dose, and spatial resolution in a radiation field incorporating high gradients. Beam profile of small fields and output factors measured on a Varian 2100EX LINAC in a 6 MV radiation fields of square dimensions and sized from 0.5 × 0.5 cm 2 to 5 × 5 cm 2 . The DUO response was compared under the same conditions with EBT3 films and an ionization chamber. The DUO detector shows a dose per pulse dependence of 5% for a range of dose rates from 2.7 × 10 -4 to 1.2 × 10 -4 Gy/pulse and 23% when the rate is further reduced to 2.8 × 10 -5 Gy/pulse. The percentage depth dose measured to 25 cm depth in solid water phantom beyond the surface and for a field size of 10 × 10 cm 2 agrees with that measured using a Markus IC within 1.5%. The beam profiles in both X and Y orthogonal directions showed a good match with EBT3 film, where the FWHM agreed within 1% and penumbra widths within 0.5 mm. The effect of an air gap above the DUO detector has also been studied. The output factor for field sizes ranging from 0.5 × 0.5 cm 2 to 5 × 5 cm 2 measured by the DUO detector with a 0.5 mm air gap above silicon surface agrees with EBT3 film and MOSkin detectors within 1.8%. The CMRP's monolithic silicon detector array, DUO, is suitable for SRS/SRT dosimetry and QA because of its very high spatial resolution (0.2 mm) and real time operation. © 2016 American Association of Physicists in Medicine.

Use of UAVs for Remote Measurement of Vegetation Canopy Variables

NASA Astrophysics Data System (ADS)

Rango, A.; Laliberte, A.; Herrick, J.; Steele, C.; Bestelmeyer, B.; Chopping, M. J.

2006-12-01

Remote sensing with different sensors has proven useful for measuring vegetation canopy variables at scales ranging from landscapes down to individual plants. For use at landscape scales, such as desert grasslands invaded by shrubs, it is possible to use multi-angle imagery from satellite sensors, such as MISR and CHRIS/Proba, with geometric optical models to retrieve fractional woody plant cover. Vegetation community states can be mapped using visible and near infrared ASTER imagery at 15 m resolution. At finer scales, QuickBird satellite imagery with approximately 60 cm resolution and piloted aircraft photography with 25-80 cm resolution can be used to measure shrubs above a critical size. Tests conducted with the QuickBird data in the Jornada basin of southern New Mexico have shown that 87% of all shrubs greater than 2 m2 were detected whereas only about 29% of all shrubs less than 2 m2 were detected, even at these high resolutions. Because there is an observational gap between satellite/aircraft measurements and ground observations, we have experimented with Unmanned Aerial Vehicles (UAVs) producing digital photography with approximately 5 cm resolution. We were able to detect all shrubs greater than 2 m2, and we were able to map small subshrubs indicative of rangeland deterioration, as well as remnant grass patches, for the first time. None of these could be identified on the 60 cm resolution data. Additionally, we were able to measure canopy gaps, shrub patterns, percent bare soil, and vegetation cover over mixed rangeland vegetation. This approach is directly applicable to rangeland health monitoring, and it provides a quantitative way to assess shrub invasion over time and to detect the depletion or recovery of grass patches. Further, if the UAV images have sufficient overlap, it may be possible to exploit the stereo viewing capabilities to develop a digital elevation model from the orthophotos, with a potential for extracting canopy height. We envision two parallel routes for investigation: one which emphasizes utilization of the most technically advanced passive and active space and aircraft sensors (e.g., LIDAR, radar, Hyperion, ASTER, QuickBird follow-on) for modeling research, and a second which emphasizes minimization of costs and maximization of simplicity for monitoring purposes utilizing inexpensive sensors such as digital cameras on UAVs for arid and semiarid rangelands. The use of UAVs will provide management agencies a way to assess various vegetation canopy variables for a very reasonable cost.

Mid-Infrared Study of Samples from Multiple Stones from the Sutters Mill Meteorite

NASA Technical Reports Server (NTRS)

Sandford, S. A.; Nuevo, M.; Flynn, G. J.; Wirick, S.

2013-01-01

The Sutter's Mill meteorite fell in N. California on April 22, 2012 and numerous pieces have been recovered and studied. We present Fourier transform infrared (FTIR) spectra of fragments from several stones of the meteorite. Methods and analysis: Infrared spectra of the samples were recorded with a Nicolet iN10 MX FTIR microscope in the mid-IR range (4000-675/cm; spectral resolution 4/cm). All samples were deposited on a clean glass slide, crushed with a stainless steel roller tool, and placed directly on the focal plane of the microscope. IR spectra were collected by averaging 128 scans. Results: Preliminary IR spectra of the non-fusion crust samples show mineral compositions that are dominated by phyllosilicates, carbonates, or mixtures of both [2]. The carbonates display a dominant, broad band centered at 1433/cm, with additional bands at 2515/cm, 1797/cm, 882/cm, and 715/cm). Features associated with phyllosilicates include a symmetric Si-O stretching mode band centered at 1011/cm and several O-H stretching mode bands. The O-H shows up in two forms (1) a broadband centered at 3415/cm that is probably largely due to adsorbed H2O and (2) a much weaker, narrower feature centered near 3680/cm due to structural -OH. Features observed in the 2985-2855/cm range suggest the presence of aliphatic -CH3 and -CH2- groups. The relative intensities of the bands in this range are somewhat unusual. Typically, the asymmetric aliphatic CH stretching bands are stronger than the symmetric stretching bands, but in this case the reverse is true. This unusual pattern is well matched by the aliphatic features seen in the spectrum of a terrestrial calcite (CaCO3) standard. This observation, and the fact that the strength of the carbonate and aliphatic bands seem to correlate, suggest the organics are associated with the carbonates. Conclusions: IR spectra of samples from the Sutter's Mill meteorite show absorption features associated with carbonates, phyllosilicates, and organics. Both the unusual band profile of the aliphatic C-H stretching mode bands and their correlation with the strength of the carbonate bands suggests the organics and the carbonates are associated in some manner.

The visible absorption spectrum of NO3 measured by high-resolution Fourier transform spectroscopy

NASA Astrophysics Data System (ADS)

Orphal, J.; Fellows, C. E.; Flaud, P.-M.

2003-02-01

The visible absorption spectrum of the nitrate radical NO3 has been measured using high-resolution Fourier transform spectroscopy. The spectrum was recorded at 294 K using a resolution of 0.6 cm-1 (corresponding to 0.026 nm at 662 nm) and covers the 12600-21500 cm-1 region (465-794 nm). Compared to absorption spectra of NO3 recorded previously, the new data show improvements concerning absolute wavelength calibration (uncertainty 0.02 cm-1), and spectral resolution. A new interpretation and model of the temperature dependence of the strong (0-0) band around 662 nm are proposed. The results are important for long-path tropospheric absorption measurements of NO3 and optical remote sensing of the Earth's atmosphere from space.

Self-Broadening and Self-Shift Coefficients in the Fundamental Band of 12C 16O

NASA Technical Reports Server (NTRS)

Devi, Malathy V.; Benner, D. Chris; Smith, Mary Ann H.; Rinsland, Curtis P.

1998-01-01

High quality and precise measurements of self-broadened and self-shift coefficients in the fundamental band of C-12O-16 were made using spectra recorded at room temperature with the high-resolution (0.0027 cm(exp -1)) McMath-Pierce Fourier transform spectrometer located at the National Solar Observatory on Kitt Peak, Arizona. The spectral region under investigation (2008-2247 cm(exp -1)) contains the P(31) to R(31) transitions. The data were obtained using a high-purity natural isotopic sample ofcarbon monoxide and two absorption cells with pathlengths of 4.08 and 9.98 cm, respectively. Various pressures of CO were used, ranging between 0.25 and 201.2 Torr. The results were obtained by analyzing five spectra simultaneously, using a multispectrum nonlinear least-squares fitting technique. The self-broadened coefficients ranged from 0.0426(2) cm(exp -1) atm(exp -1) at 296 K to 0.0924(2) cm(exp -1) atm(exp -1) at 296 K, while the pressure-induced shift coefficients varied between -0.0042(3) cm(exp -1) atm(exp -1) at 296 K and +0.0005(l) cm(exp -1) atm(exp -1) at 296 K. The value in parentheses is the estimated uncertainty in units of the last digit. The self-broadened coefficients of lines with same values of m in the P and R branches agree close to within experimental uncertainties while the self-shift coefficients showed considerable variation within and between the two branches. The mean value of the ratios of P branch to R branch self-broadened coefficients was found to be 1.01 with a standard deviation of + or - 0.01. Comparisons of the results with other published data were made.

[Effect of the near infrared spectrum resolution on the nitrogen content model in green tea].

PubMed

Yang, Dan; Liu, Xin; Liu, Hong-Gang; Zhang, Ying-Bin; Yin, Peng

2013-07-01

The effect of different resolutions(2, 4, 6, 8, 16 cm(-1)) on the near infrared spectrogram and nitrogen content model for green tea was studied. Test results showed that instrument resolution could influence the spectra quality. The higher the resolution was, the richer the information would be, but the noise would increase. With lower resolution, spectrogram would be much more smooth, but get seriously distorted, and prediction accuracy would decrease at the same time. The partial least squares model was built after spectral pretreatment. When resolution was 4 cm(-1), the RMSEP value of external validation set was 0.054 6, which was obviously lower than others. The Corr. Coeff. was 0.998 2. Its prediction performance was the best and the prediction accuracy better. STDEV and RSD were 0.020 and 0.334 respectively. Resolution 4 cm(-1) for near infrared spectrometer collecting green tea samples was the optimal resolution. This research can provide a reference for parameters selection when collecting green tea spectra with near infrared spectrometer, improve the stability and prediction performance of the model and promote the application and promotion of the near infrared spectroscopy for tea.

The BRIDGE HadCM3 family of climate models: HadCM3@Bristol v1.0

NASA Astrophysics Data System (ADS)

Valdes, Paul J.; Armstrong, Edward; Badger, Marcus P. S.; Bradshaw, Catherine D.; Bragg, Fran; Crucifix, Michel; Davies-Barnard, Taraka; Day, Jonathan J.; Farnsworth, Alex; Gordon, Chris; Hopcroft, Peter O.; Kennedy, Alan T.; Lord, Natalie S.; Lunt, Dan J.; Marzocchi, Alice; Parry, Louise M.; Pope, Vicky; Roberts, William H. G.; Stone, Emma J.; Tourte, Gregory J. L.; Williams, Jonny H. T.

2017-10-01

Understanding natural and anthropogenic climate change processes involves using computational models that represent the main components of the Earth system: the atmosphere, ocean, sea ice, and land surface. These models have become increasingly computationally expensive as resolution is increased and more complex process representations are included. However, to gain robust insight into how climate may respond to a given forcing, and to meaningfully quantify the associated uncertainty, it is often required to use either or both ensemble approaches and very long integrations. For this reason, more computationally efficient models can be very valuable tools. Here we provide a comprehensive overview of the suite of climate models based around the HadCM3 coupled general circulation model. This model was developed at the UK Met Office and has been heavily used during the last 15 years for a range of future (and past) climate change studies, but has now been largely superseded for many scientific studies by more recently developed models. However, it continues to be extensively used by various institutions, including the BRIDGE (Bristol Research Initiative for the Dynamic Global Environment) research group at the University of Bristol, who have made modest adaptations to the base HadCM3 model over time. These adaptations mean that the original documentation is not entirely representative, and several other relatively undocumented configurations are in use. We therefore describe the key features of a number of configurations of the HadCM3 climate model family, which together make up HadCM3@Bristol version 1.0. In order to differentiate variants that have undergone development at BRIDGE, we have introduced the letter B into the model nomenclature. We include descriptions of the atmosphere-only model (HadAM3B), the coupled model with a low-resolution ocean (HadCM3BL), the high-resolution atmosphere-only model (HadAM3BH), and the regional model (HadRM3B). These also include three versions of the land surface scheme. By comparing with observational datasets, we show that these models produce a good representation of many aspects of the climate system, including the land and sea surface temperatures, precipitation, ocean circulation, and vegetation. This evaluation, combined with the relatively fast computational speed (up to 1000 times faster than some CMIP6 models), motivates continued development and scientific use of the HadCM3B family of coupled climate models, predominantly for quantifying uncertainty and for long multi-millennial-scale simulations.

Lack of robustness of textural measures obtained from 3D brain tumor MRIs impose a need for standardization

PubMed Central

Pérez-Beteta, Julián; Martínez-González, Alicia; Martino, Juan; Velasquez, Carlos; Arana, Estanislao; Pérez-García, Víctor M.

2017-01-01

Purpose Textural measures have been widely explored as imaging biomarkers in cancer. However, their robustness under dynamic range and spatial resolution changes in brain 3D magnetic resonance images (MRI) has not been assessed. The aim of this work was to study potential variations of textural measures due to changes in MRI protocols. Materials and methods Twenty patients harboring glioblastoma with pretreatment 3D T1-weighted MRIs were included in the study. Four different spatial resolution combinations and three dynamic ranges were studied for each patient. Sixteen three-dimensional textural heterogeneity measures were computed for each patient and configuration including co-occurrence matrices (CM) features and run-length matrices (RLM) features. The coefficient of variation was used to assess the robustness of the measures in two series of experiments corresponding to (i) changing the dynamic range and (ii) changing the matrix size. Results No textural measures were robust under dynamic range changes. Entropy was the only textural feature robust under spatial resolution changes (coefficient of variation under 10% in all cases). Conclusion Textural measures of three-dimensional brain tumor images are not robust neither under dynamic range nor under matrix size changes. Standards should be harmonized to use textural features as imaging biomarkers in radiomic-based studies. The implications of this work go beyond the specific tumor type studied here and pose the need for standardization in textural feature calculation of oncological images. PMID:28586353

Preliminary study of a new gamma imager for on-line proton range monitoring during proton radiotherapy

NASA Astrophysics Data System (ADS)

Bennati, P.; Dasu, A.; Colarieti-Tosti, M.; Lönn, G.; Larsson, D.; Fabbri, A.; Galasso, M.; Cinti, M. N.; Pellegrini, R.; Pani, R.

2017-05-01

We designed and tested new concept imaging devices, based on a thin scintillating crystal, aimed at the online monitoring of the range of protons in tissue during proton radiotherapy. The proposed crystal can guarantee better spatial resolution and lower sensitivity with respect to a thicker one, at the cost of a coarser energy resolution. Two different samples of thin crystals were coupled to a position sensitive photo multiplier tube read out by 64 independent channels electronics. The detector was equipped with a knife-edge Lead collimator that defined a reasonable field of view of about 10 cm in the target. Geant4 Monte Carlo simulations were used to optimize the design of the experimental setup and assess the accuracy of the results. Experimental measurements were carried out at the Skandion Clinic, the recently opened proton beam facility in Uppsala, Sweden. PMMA and water phantoms studies were performed with a first prototype based on a round 6.0 mm thick Cry019 crystal and with a second detector based on a thinner 5 × 5 cm2, 2.0 mm thick LFS crystal. Phantoms were irradiated with mono-energetic proton beams whose energy was in the range between 110 and 160 MeV. According with the simulations and the experimental data, the detector based on LFS crystal seems able to identify the peak of prompt-gamma radiation and its results are in fair agreement with the expected shift of the proton range as a function of energy. The count rate remains one of the most critical limitations of our system, which was able to cope with only about 20% of the clinical dose rate. Nevertheless, we are confident that our study might provide the basis for developing a new full-functional system.

The future of primordial features with 21 cm tomography

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

Chen, Xingang; Meerburg, P. Daniel; Münchmeyer, Moritz, E-mail: xingang.chen@cfa.harvard.edu, E-mail: meerburg@cita.utoronto.ca, E-mail: munchmey@iap.fr

2016-09-01

Detecting a deviation from a featureless primordial power spectrum of fluctuations would give profound insight into the physics of the primordial Universe. Depending on their nature, primordial features can either provide direct evidence for the inflation scenario or pin down details of the inflation model. Thus far, using the cosmic microwave background (CMB) we have only been able to put stringent constraints on the amplitude of features, but no significant evidence has been found for such signals. Here we explore the limit of the experimental reach in constraining such features using 21 cm tomography at high redshift. A measurement ofmore » the 21 cm power spectrum from the Dark Ages is generally considered as the ideal experiment for early Universe physics, with potentially access to a large number of modes. We consider three different categories of theoretically motivated models: the sharp feature models, resonance models, and standard clock models. We study the improvements on bounds on features as a function of the total number of observed modes and identify parameter degeneracies. The detectability depends critically on the amplitude, frequency and scale-location of the features, as well as the angular and redshift resolution of the experiment. We quantify these effects by considering different fiducial models. Our forecast shows that a cosmic variance limited 21 cm experiment measuring fluctuations in the redshift range 30 ≤ z ≤ 100 with a 0.01-MHz bandwidth and sub-arcminute angular resolution could potentially improve bounds by several orders of magnitude for most features compared to current Planck bounds. At the same time, 21 cm tomography also opens up a unique window into features that are located on very small scales.« less

Ultra-Wideband Chaos Life-Detection Radar with Sinusoidal Wave Modulation

NASA Astrophysics Data System (ADS)

Xu, Hang; Li, Ying; Zhang, Jianguo; Han, Hong; Zhang, Bing; Wang, Longsheng; Wang, Yuncai; Wang, Anbang

2017-12-01

We propose and experimentally demonstrate an ultra-wideband (UWB) chaos life-detection radar. The proposed radar transmits a wideband chaotic-pulse-position modulation (CPPM) signal modulated by a single-tone sinusoidal wave. A narrow-band split ring sensor is used to collect the reflected sinusoidal wave, and a lock-in amplifier is utilized to identify frequencies of respiration and heartbeat by detecting the phase change of the sinusoidal echo signal. Meanwhile, human location is realized by correlating the CPPM echo signal with its delayed duplicate and combining the synthetic aperture technology. Experimental results demonstrate that the human target can be located accurately and his vital signs can be detected in a large dynamic range through a 20-cm-thick wall using our radar system. The down-range resolution is 15cm, benefiting from the 1-GHz bandwidth of the CPPM signal. The dynamic range for human location is 50dB, and the dynamic ranges for heartbeat and respiration detection respectively are 20dB and 60dB in our radar system. In addition, the bandwidth of the CPPM signal can be adjusted from 620MHz to 1.56GHz to adapt to different requirements.

The WFM Instrument of the LOFT mission

NASA Astrophysics Data System (ADS)

Gálvez, J. L.; Hernanz, M.; Álvarez, L.; LOFT/WFM Team

2013-05-01

LOFT, the Large Observatory For X-ray Timing, was selected by ESA in 2011 as one of the four M3 (medium class) missions concepts of the Cosmic Vision programme that will compete for a launch opportunity at the start of the 2020s. LOFT includes two instruments: the Large Area Detector (LAD), a ˜10 m^2 collimated X-ray detector in the 2-50 keV range (up to 80 keV in extended mode), and the Wide Field Monitor (WFM), a coded-mask wide field X-ray monitor based on silicon radiation detectors. We, the Institute of Space Sciences (CSIC-IEEC) in Barcelona, are deeply involved in the LOFT mission, sharing the leadership of the WFM instrument with DTU Space in Denmark. We are responsible of the mechanics of the WFM, including the structural and thermal design. The WFM baseline is a set of 4 units (each unit corresponds to 2 co-aligned cameras) arranged in arch, covering a field of view at zero response of 180°× 90°, and one more unit pointing to the anti-sun direction. The structure of each camera lies on its own coded mask of Tungsten, 150 μm thick, a collimator and the detector plane (20 cm below the mask) providing a fine (arc minutes) angular resolution. The camera detector plane (182 cm^2) will operate at -20°C in order to achieve an energy resolution FWHM of less than 500 eV in the 2-50 keV energy range. The WFM has the main scope of catching good triggering sources to be pointed with the LAD. Its large field of view will permit to observe in the same energy range of the LAD about 50% of the sky at once. The WFM is designed also to catch transient/bursting events down to a few mCrab fluxes and will provide for them data with fine spectral and timing resolution (up to 10 μsec).

Waves on Thin Plates: A New (Energy Based) Method on Localization

NASA Astrophysics Data System (ADS)

Turkaya, Semih; Toussaint, Renaud; Kvalheim Eriksen, Fredrik; Lengliné, Olivier; Daniel, Guillaume; Grude Flekkøy, Eirik; Jørgen Måløy, Knut

2016-04-01

Noisy acoustic signal localization is a difficult problem having a wide range of application. We propose a new localization method applicable for thin plates which is based on energy amplitude attenuation and inversed source amplitude comparison. This inversion is tested on synthetic data using a direct model of Lamb wave propagation and on experimental dataset (recorded with 4 Brüel & Kjær Type 4374 miniature piezoelectric shock accelerometers, 1 - 26 kHz frequency range). We compare the performance of this technique with classical source localization algorithms, arrival time localization, time reversal localization, localization based on energy amplitude. The experimental setup consist of a glass / plexiglass plate having dimensions of 80 cm x 40 cm x 1 cm equipped with four accelerometers and an acquisition card. Signals are generated using a steel, glass or polyamide ball (having different sizes) quasi perpendicular hit (from a height of 2-3 cm) on the plate. Signals are captured by sensors placed on the plate on different locations. We measure and compare the accuracy of these techniques as function of sampling rate, dynamic range, array geometry, signal to noise ratio and computational time. We show that this new technique, which is very versatile, works better than conventional techniques over a range of sampling rates 8 kHz - 1 MHz. It is possible to have a decent resolution (3cm mean error) using a very cheap equipment set. The numerical simulations allow us to track the contributions of different error sources in different methods. The effect of the reflections is also included in our simulation by using the imaginary sources outside the plate boundaries. This proposed method can easily be extended for applications in three dimensional environments, to monitor industrial activities (e.g boreholes drilling/production activities) or natural brittle systems (e.g earthquakes, volcanoes, avalanches).

Lineshape measurements of He- β spectra on the ORION laser facility

DOE PAGES

Beiersdorfer, P.; Brown, G. V.; Shepherd, R.; ...

2016-10-25

Here, we have utilized a newly developed high-resolution X-ray spectrometer to measure the shapes of spectral lines produced from laser-irradiated targets on the Orion laser facility in the United Kingdom. We present measurements of the He-β spectra of chlorine and chromium from targets irradiated by either a long-pulse or a short-pulse laser beam. The experimental conditions provide a spread in plasma density ranging from about 10 19 to about 10 24 cm –3. We present spectral calculations that show that the relative intensities of the Li-like satellite lines can be used to infer the density in the lower range, especiallymore » if the lithiumlike satellite lines are well resolved. In addition, we use the Stark-broadened width of the He-β line to infer densities above about 10 22 cm –3. In the case of a short-pulse irradiated chromium foil, we find that the He-like chromium is produced at a density of almost 8 g/cm 3, i.e., solid density. In addition, we can infer the electron temperature from the observation of dielectronic recombination satellite lines.« less

A novel setup for femtosecond pump-repump-probe IR spectroscopy with few cycle CEP stable pulses.

PubMed

Bradler, Maximilian; Werhahn, Jasper C; Hutzler, Daniel; Fuhrmann, Simon; Heider, Rupert; Riedle, Eberhard; Iglev, Hristo; Kienberger, Reinhard

2013-08-26

We present a three-color mid-IR setup for vibrational pump-repump-probe experiments with a temporal resolution well below 100 fs and a freely selectable spectral resolution of 20 to 360 cm(-1) for the pump and repump. The usable probe range without optical realignment is 900 cm(-1). The experimental design employed is greatly simplified compared to the widely used setups, highly robust and includes a novel means for generation of tunable few-cycle pulses with stable carrier-envelope phase. A Ti:sapphire pump system operating with 1 kHz and a modest 150 fs pulse duration supplies the total pump energy of just 0.6 mJ. The good signal-to-noise ratio of the setup allows the determination of spectrally resolved transient probe changes smaller than 6·10(-5) OD at 130 time delays in just 45 minutes. The performance of the spectrometer is demonstrated with transient IR spectra and decay curves of HDO molecules in lithium nitrate trihydrate and ice and a first all MIR pump-repump-probe measurement.

The Fabrication and Characterization of Ni/4H-SiC Schottky Diode Radiation Detectors with a Sensitive Area of up to 4 cm².

PubMed

Liu, Lin-Yue; Wang, Ling; Jin, Peng; Liu, Jin-Liang; Zhang, Xian-Peng; Chen, Liang; Zhang, Jiang-Fu; Ouyang, Xiao-Ping; Liu, Ao; Huang, Run-Hua; Bai, Song

2017-10-13

Silicon carbide (SiC) detectors of an Ni/4H-SiC Schottky diode structure and with sensitive areas of 1-4 cm² were fabricated using high-quality lightly doped epitaxial 4H-SiC material, and were tested in the detection of alpha particles and pulsed X-rays/UV-light. A linear energy response to alpha particles ranging from 5.157 to 5.805 MeV was obtained. The detectors were proved to have a low dark current, a good energy resolution, and a high neutron/gamma discrimination for pulsed radiation, showing the advantages in charged particle detection and neutron detection in high-temperature and high-radiation environments.

Observations Of Planetary Nebula NGC 3242 Using STIS From HST19 GO 12600

NASA Astrophysics Data System (ADS)

Miller, Timothy R.; Dufour, Reginald J.; Henry, Richard B. C.; Kwitter, Karen B.; Shaw, Richard A.; Balick, Bruce; Corradi, Romano

2014-06-01

During HST Cycle 19, we obtained long-slit spectra using STIS of the planetary nebula NGC 3242 with higher spatial resolution than previously published. The full wavelength range is around 1100-10200Å, covering many nebular lines for determining numerous ionic abundances and electron densities and temperatures. In this work, we first analyze the low- and moderate-resolution UV emission lines of carbon, nitrogen and oxygen. In particular, the resolved lines of C_III] 1907 and C_III] 1909 have yielded a direct measurement of one of the dominant ionic species for carbon and a determination of the density occupied by doubly-ionized carbon and other similar ions. Next, the spatial emission profile of these lines reveals variations in the inferred density along the line of sight from about 2800-11500 cm-3, compared with a value ~3800 cm-3, when averaged over the entire slit. Similarly, the electron temperature is around 12000K for the entire slit and ranges from about 11400-14000K when the slit is divided into smaller sub-regions. Lastly, these sub-regions of the nebula have been modeled in detail with the photoionization code CLOUDY. This modeling will assess the density profile that produces the observed density variation, reproduce the temperature fluctuations, and constrain the central star temperature. We acknowledge the gracious support from HST and the University of Oklahoma.

[Retrieval of the Optical Thickness and Cloud Top Height of Cirrus Clouds Based on AIRS IR High Spectral Resolution Data].

PubMed

Cao, Ya-nan; Wei, He-li; Dai, Cong-ming; Zhang, Xue-hai

2015-05-01

A study was carried out to retrieve optical thickness and cloud top height of cirrus clouds from the Atmospheric Infrared Sounder (AIRS) high spectral resolution data in 1070~1135 cm-1 IR band using a Combined Atmospheric Radiative Transfer model (CART) by brightness temperature difference between model simulation and AIRS observation. The research is based on AIRS LIB high spectral infrared observation data combined with Moderate Resolution Imaging Spectroradiometer (MODIS) cloud product data. Brightness temperature spectra based, on the retrieved cirrus optical thickness and cloud top height were simulated and compared with brightness temperature spectra of AIRS observation in the 650~1150 cm-1 band. The cirrus optical thickness and cloud top height retrieved were compared with brightness temperature of AIRS for channel 760 (900.56 cm-1, 11. 1 µm) and cirrus reflectance of MODIS cloud product. And cloud top height retrieved was compared with cloud top height from MODIS. Results show that the brightness temperature spectra simulated were basically consistent with AIRS observation under the condition of retrieval in the 650~1150 cm-1 band. It means that CART can be used to simulate AIRS brightness temperature spectra. The retrieved cirrus parameters are consistent with brightness temperature of AIRS for channel 11. 1 µm with low brightness temperature corresponding to large cirrus optical thickness and high cloud top height. And the retrieved cirrus parameters are consistent with cirrus reflectance of MODIS cloud product with high cirrus reflectance corresponding to large cirrus optical thickness and high cloud top height. Correlation coefficient of brightness temperature between retrieved cloud top height and MODIS cloud top height was relatively high. They are mostly located in the range of 8. 5~11.5 km, and their probability distribution trend is approximately identical. CART model is feasible to retrieve cirrus properties, and the retrieval is reliable.

The Influence of Sampling Density on Bayesian Age-Depth Models and Paleoclimatic Reconstructions - Lessons Learned from Lake Titicaca - Bolivia/Peru

NASA Astrophysics Data System (ADS)

Salenbien, W.; Baker, P. A.; Fritz, S. C.; Guedron, S.

2014-12-01

Lake Titicaca is one of the most important archives of paleoclimate in tropical South America, and prior studies have elucidated patterns of climate variation at varied temporal scales over the past 0.5 Ma. Yet, slow sediment accumulation rates in the main deeper basin of the lake have precluded analysis of the lake's most recent history at high resolution. To obtain a paleoclimate record of the last few millennia at multi-decadal resolution, we obtained five short cores, ranging from 139 to 181 cm in length, from the shallower Wiñaymarka sub-basin of of Lake Titicaca, where sedimentation rates are higher than in the lake's main basin. Selected cores have been analyzed for their geochemical signature by scanning XRF, diatom stratigraphy, sedimentology, and for 14C age dating. A total of 72 samples were 14C-dated using a Gas Ion Source automated high-throughput method for carbonate samples (mainly Littoridina sp. and Taphius montanus gastropod shells) at NOSAMS (Woods Hole Oceanographic Institute) with an analytical precision higher than 2%. The method has lower analytical precision compared with traditional AMS radiocarbon dating, but the lower cost enables analysis of a larger number of samples, and the error associated with the lower precision is relatively small for younger samples (< ~8,000 years). A 172-cm-long core was divided into centimeter long sections, and 47 14C dates were obtained from 1-cm intervals, averaging one date every 3-4 cm. The other cores were radiocarbon dated with a sparser sampling density that focused on visual unconformities and shell beds. The high-resolution radiocarbon analysis reveals complex sedimentation patterns in visually continuous sections, with abundant indicators of bioturbated or reworked sediments and periods of very rapid sediment accumulation. These features are not evident in the sparser sampling strategy but have significant implications for reconstructing past lake level and paleoclimatic history.

Spectral monitoring of toluene and ethanol in gasoline blends using Fourier-Transform Raman spectroscopy

NASA Astrophysics Data System (ADS)

Ortega Clavero, Valentin; Weber, Andreas; Schröder, Werner; Curticapean, Dan; Meyrueis, Patrick; Javahiraly, Nicolas

2013-04-01

The combination of fossil-derived fuels with ethanol and methanol has acquired relevance and attention in several countries in recent years. This trend is strongly affected by market prices, constant geopolitical events, new sustainability policies, new laws and regulations, etc. Besides bio-fuels these materials also include different additives as anti-shock agents and as octane enhancer. Some of the chemical compounds in these additives may have harmful properties for both environment and public health (besides the inherent properties, like volatility). We present detailed Raman spectral information from toluene (C7H8) and ethanol (C2H6O) contained in samples of ElO gasoline-ethanol blends. The spectral information has been extracted by using a robust, high resolution Fourier-Transform Raman spectrometer (FT-Raman) prototype. This spectral information has been also compared with Raman spectra from pure additives and with standard Raman lines in order to validate its accuracy in frequency. The spectral information is presented in the range of 0 cm-1 to 3500 cm-1 with a resolution of 1.66cm-1. This allows resolving tight adjacent Raman lines like the ones observed around 1003cm-1 and 1030cm-1 (characteristic lines of toluene). The Raman spectra obtained show a reduced frequency deviation when compared to standard Raman spectra from different calibration materials. The FT-Raman spectrometer prototype used for the analysis consist basically of a Michelson interferometer and a self-designed photon counter cooled down on a Peltier element arrangement. The light coupling is achieved with conventional62.5/125μm multi-mode fibers. This FT-Raman setup is able to extract high resolution and frequency precise Raman spectra from the additives in the fuels analyzed. The proposed prototype has no additional complex hardware components or costly software modules. The mechanical and thermal disturbances affecting the FT-Raman system are mathematically compensated by accurately extracting the optical path information of the Michelson interferometer. This is accomplished by generating an additional interference pattern with a λ = 632.8 nm Helium-Neon laser (HeNe laser). It enables the FT-Raman system to perform reliable and clean spectral measurements from the materials under observation.

Video-rate functional photoacoustic microscopy at depths

NASA Astrophysics Data System (ADS)

Wang, Lidai; Maslov, Konstantin; Xing, Wenxin; Garcia-Uribe, Alejandro; Wang, Lihong V.

2012-10-01

We report the development of functional photoacoustic microscopy capable of video-rate high-resolution in vivo imaging in deep tissue. A lightweight photoacoustic probe is made of a single-element broadband ultrasound transducer, a compact photoacoustic beam combiner, and a bright-field light delivery system. Focused broadband ultrasound detection provides a 44-μm lateral resolution and a 28-μm axial resolution based on the envelope (a 15-μm axial resolution based on the raw RF signal). Due to the efficient bright-field light delivery, the system can image as deep as 4.8 mm in vivo using low excitation pulse energy (28 μJ per pulse, 0.35 mJ/cm2 on the skin surface). The photoacoustic probe is mounted on a fast-scanning voice-coil scanner to acquire 40 two-dimensional (2-D) B-scan images per second over a 9-mm range. High-resolution anatomical imaging is demonstrated in the mouse ear and brain. Via fast dual-wavelength switching, oxygen dynamics of mouse cardio-vasculature is imaged in realtime as well.

Absolute Integral Cross Sections for the State-selected Ion-Molecule Reaction N2+(X2Σg+ v+ = 0-2) + C2H2 in the Collision Energy Range of 0.03-10.00 eV

NASA Astrophysics Data System (ADS)

Xu, Yuntao; Xiong, Bo; Chung Chang, Yih; Ng, C. Y.

2016-08-01

Using the vacuum ultraviolet laser pulsed field ionization-photoion source, together with the double-quadrupole-double-octopole mass spectrometer developed in our laboratory, we have investigated the state-selected ion-molecule reaction {{{{N}}}2}+({X}2{{{{Σ }}}{{g}}}+; v + = 0-2, N+ = 0-9) + C2H2, achieving high internal-state selectivity and high kinetic energy resolution for reactant {{{{N}}}2}+ ions. The charge transfer (CT) and hydrogen-atom transfer (HT) channels, which lead to the respective formation of product {{{C}}}2{{{{H}}}2}+ and N2H+ ions, are observed. The vibrationally selected absolute integral cross sections for the CT [σ CT(v +)] and HT [[σ HT(v +)] channels obtained in the center-of-mass collision energy (E cm) range of 0.03-10.00 eV reveal opposite E cm dependences. The σ CT(v +) is found to increase as E cm is decreased, and is consistent with the long-range exothermic CT mechanism, whereas the E cm enhancement observed for the σ HT(v +) suggests effective coupling of kinetic energy to internal energy, enhancing the formation of N2H+. The σ HT(v +) curve exhibits a step at E cm = 0.70-1.00 eV, suggesting the involvement of the excited {{{C}}}2{{{{H}}}2}+({A}2{{{{Σ }}}{{g}}}+) state in the HT reaction. Contrary to the strong E cm dependences for σ CT(v +) and σ HT(v +), the effect of vibrational excitation of {{{{N}}}2}+ on both the CT and HT channels is marginal. The branching ratios and cross sections for the CT and HT channels determined in the present study are useful for modeling the atmospheric compositions of Saturn's largest moon, Titan. These cross sections and branching ratios are also valuable for benchmarking theoretical calculations on chemical dynamics of the titled reaction.

Push-broom imaging spectrometer based on planar lightwave circuit MZI array

NASA Astrophysics Data System (ADS)

Yang, Minyue; Li, Mingyu; He, Jian-Jun

2017-05-01

We propose a large aperture static imaging spectrometer (LASIS) based on planar lightwave circuit (PLC) MZI array. The imaging spectrometer works in the push-broom mode with the spectrum performed by interferometry. While the satellite/aircraft is orbiting, the same source, seen from the satellite/aircraft, moves across the aperture and enters different MZIs, while adjacent sources enter adjacent MZIs at the same time. The on-chip spectrometer consists of 256 input mode converters, followed by 256 MZIs with linearly increasing optical path delays and a detector array. Multiple chips are stick together to form the 2D image surface and receive light from the imaging lens. Two MZI arrays are proposed, one works in wavelength ranging from 500nm to 900nm with SiON(refractive index 1.6) waveguides and another ranging from 1100nm to 1700nm with SOI platform. To meet the requirements of imaging spectrometer applications, we choose large cross-section ridge waveguide to achieve polarization insensitive, maintain single mode propagation in broad spectrum and increase production tolerance. The SiON on-chip spectrometer has a spectral resolution of 80cm-1 with a footprint of 17×15mm2 and the SOI based on-chip spectrometer has a resolution of 38cm-1 with a size of 22×19mm2. The spectral and space resolution of the imaging spectrometer can be further improved by simply adding more MZIs. The on-chip waveguide MZI array based Fourier transform imaging spectrometer can provide a highly compact solution for remote sensing on unmanned aerial vehicles or satellites with advantages of small size, light weight, no moving parts and large input aperture.

A hybrid thermal video and FTIR spectrometer system for rapidly locating and characterizing gas leaks

NASA Astrophysics Data System (ADS)

Williams, David J.; Wadsworth, Winthrop; Salvaggio, Carl; Messinger, David W.

2006-08-01

Undiscovered gas leaks, known as fugitive emissions, in chemical plants and refinery operations can impact regional air quality and present a loss of product for industry. Surveying a facility for potential gas leaks can be a daunting task. Industrial leak detection and repair programs can be expensive to administer. An efficient, accurate and cost effective method for detecting and quantifying gas leaks would both save industries money by identifying production losses and improve regional air quality. Specialized thermal video systems have proven effective in rapidly locating gas leaks. These systems, however, do not have the spectral resolution for compound identification. Passive FTIR spectrometers can be used for gas compound identification, but using these systems for facility surveys is problematic due to their small field of view. A hybrid approach has been developed that utilizes the thermal video system to locate gas plumes using real time visualization of the leaks, coupled with the high spectral resolution FTIR spectrometer for compound identification and quantification. The prototype hybrid video/spectrometer system uses a sterling cooled thermal camera, operating in the MWIR (3-5 μm) with an additional notch filter set at around 3.4 μm, which allows for the visualization of gas compounds that absorb in this narrow spectral range, such as alkane hydrocarbons. This camera is positioned alongside of a portable, high speed passive FTIR spectrometer, which has a spectral range of 2 - 25 μm and operates at 4 cm -1 resolution. This system uses a 10 cm telescope foreoptic with an onboard blackbody for calibration. The two units are optically aligned using a turning mirror on the spectrometer's telescope with the video camera's output.

A high resolution small animal radiation research platform (SARRP) with x-ray tomographic guidance capabilities

PubMed Central

Wong, John; Armour, Elwood; Kazanzides, Peter; Iordachita, Iulian; Tryggestad, Erik; Deng, Hua; Matinfar, Mohammad; Kennedy, Christopher; Liu, Zejian; Chan, Timothy; Gray, Owen; Verhaegen, Frank; McNutt, Todd; Ford, Eric; DeWeese, Theodore L.

2008-01-01

Purpose To demonstrate the CT imaging, conformal irradiation and treatment planning capabilities of a small animal radiation research platform (SARRP). Methods The SARRP employs a dual-focal spot, constant voltage x-ray source mounted on a gantry with a source-to-isocenter distance of 35 cm. Gantry rotation is limited to 120° from vertical. Eighty to 100 kVp x-rays from the smaller 0.4 mm focal spot are used for imaging. Both 0.4 mm and 3.0 mm focal spots operate at 225 kVp for irradiation. Robotic translate/rotate stages are used to position the animal. Cone-beam (CB) CT imaging is achieved by rotating the horizontal animal between the stationary x-ray source and a flat-panel detector. Radiation beams range from 0.5 mm in diameter to (60 × 60) mm2. Dosimetry is measured with radio-chromic films. Monte Carlo dose calculations are employed for treatment planning. The combination of gantry and robotic stage motions facilitate conformal irradiation. Results The SARRP spans 3 ft × 4 ft × 6 ft (WxLxH). Depending on filtration, the isocenter dose outputs at 1 cm depth in water range from 22 to 375 cGy/min from the smallest to the largest radiation fields. The 20% to 80% dose fall-off spans 0.16 mm. CBCT with (0.6 × 0.6 × 0.6) mm3 voxel resolution is acquired with less than 1 cGy. Treatment planning is performed at sub-mm resolution. Conclusions The capability of the SARRP to deliver highly focal beams to multiple animal model systems provides new research opportunities that more realistically bridge laboratory research and clinical translation. PMID:18640502

Operation and performance of the New Horizons Long-Range Reconnaissance Imager during the Pluto encounter

NASA Astrophysics Data System (ADS)

Conard, S. J.; Weaver, H. A.; Núñez, J. I.; Taylor, H. W.; Hayes, J. R.; Cheng, A. F.; Rodgers, D. J.

2017-09-01

The Long-Range Reconnaissance Imager (LORRI) is a high-resolution imaging instrument on the New Horizons spacecraft. LORRI collected over 5000 images during the approach and fly-by of the Pluto system in 2015, including the highest resolution images of Pluto and Charon and the four much smaller satellites (Styx, Nix, Kerberos, and Hydra) near the time of closest approach on 14 July 2015. LORRI is a narrow field of view (0.29°), Ritchey-Chrétien telescope with a 20.8 cm diameter primary mirror and a three-lens field flattener. The telescope has an effective focal length of 262 cm. The focal plane unit consists of a 1024 × 1024 pixel charge-coupled device (CCD) detector operating in frame transfer mode. LORRI provides panchromatic imaging over a bandpass that extends approximately from 350 nm to 850 nm. The instrument operates in an extreme thermal environment, viewing space from within the warm spacecraft. For this reason, LORRI has a silicon carbide optical system with passive thermal control, designed to maintain focus without adjustment over a wide temperature range from -100 C to +50 C. LORRI operated flawlessly throughout the encounter period, providing both science and navigation imaging of the Pluto system. We describe the preparations for the Pluto system encounter, including pre-encounter rehearsals, calibrations, and navigation imaging. In addition, we describe LORRI operations during the encounter, and the resulting imaging performance. Finally, we also briefly describe the post-Pluto encounter imaging of other Kuiper belt objects and the plans for the upcoming encounter with KBO 2014 MU69.

The structure of the interstellar medium at the 25 AU scale

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

Diamond, P.J.; Goss, W.M.; Romney, J.D.

1989-12-01

A three-station VLBI Galactic H I absorption experiment has been carried out with baselines up to 600 km. The large collecting area of the European VLBI Network consisting of the Lovell Telescope (Mark Ia), the 100 m telescope at Effelsberg, and the Westerbork Synthesis Radio Telescope was necessary to achieve adequate sensitivity for these high angular resolution (0.05 arcsec) and high-velocity resolution (0.5 km/s) observations. The extragalactic sources 3C 138, 3C 147, and 3C 380 were observed. Changes in the local H I apparent absorption were observed in all three sources as a function of resolution. The changes are mostmore » striking in the direction of 3C 138. The implied linear diameters are in the range 25 AU with typical H I densities of 10,000-100,000/cu cm. 19 refs.« less

Design study of a high-resolution breast-dedicated PET system built from cadmium zinc telluride detectors

PubMed Central

Peng, Hao; Levin, Craig S

2013-01-01

We studied the performance of a dual-panel positron emission tomography (PET) camera dedicated to breast cancer imaging using Monte Carlo simulation. The proposed system consists of two 4 cm thick 12 × 15 cm2 area cadmium zinc telluride (CZT) panels with adjustable separation, which can be put in close proximity to the breast and/or axillary nodes. Unique characteristics distinguishing the proposed system from previous efforts in breast-dedicated PET instrumentation are the deployment of CZT detectors with superior spatial and energy resolution, using a cross-strip electrode readout scheme to enable 3D positioning of individual photon interaction coordinates in the CZT, which includes directly measured photon depth-of-interaction (DOI), and arranging the detector slabs edge-on with respect to incoming 511 keV photons for high photon sensitivity. The simulation results show that the proposed CZT dual-panel PET system is able to achieve superior performance in terms of photon sensitivity, noise equivalent count rate, spatial resolution and lesion visualization. The proposed system is expected to achieve ~32% photon sensitivity for a point source at the center and a 4 cm panel separation. For a simplified breast phantom adjacent to heart and torso compartments, the peak noise equivalent count (NEC) rate is predicted to be ~94.2 kcts s−1 (breast volume: 720 cm3 and activity concentration: 3.7 kBq cm−3) for a ~10% energy window around 511 keV and ~8 ns coincidence time window. The system achieves 1 mm intrinsic spatial resolution anywhere between the two panels with a 4 cm panel separation if the detectors have DOI resolution less than 2 mm. For a 3 mm DOI resolution, the system exhibits excellent sphere resolution uniformity (σrms/mean) ≤ 10%) across a 4 cm width FOV. Simulation results indicate that the system exhibits superior hot sphere visualization and is expected to visualize 2 mm diameter spheres with a 5:1 activity concentration ratio within roughly 7 min imaging time. Furthermore, we observe that the degree of spatial resolution degradation along the direction orthogonal to the two panels that is typical of a limited angle tomography configuration is mitigated by having high-resolution DOI capabilities that enable more accurate positioning of oblique response lines. PMID:20400807

Performance simulation of a compact PET insert for simultaneous PET/MR breast imaging

NASA Astrophysics Data System (ADS)

Liang, Yicheng; Peng, Hao

2014-07-01

We studied performance metrics of a small PET ring designed to be integrated with a breast MRI coil. Its performance was characterized using a Monte Carlo simulation of a system with the best possible design features we believe are technically available, with respect to system geometry, spatial resolution, shielding, and lesion detectability. The results indicate that the proposed system is able to achieve about 6.2% photon detection sensitivity at the center of field-of-view (FOV) (crystal design: 2.2×2.2×20 mm3, height: 3.4 cm). The peak noise equivalent count rate (NECR) is found to be 7886 cps with a time resolution of 250 ps (time window: 500 ps). With the presence of lead shielding, the NECR increases by a factor of 1.7 for high activity concentrations within the breast (>0.9 μCi/mL), while no noticeable benefit is observed in the range of activities currently being used in the clinical setting. In addition, the system is able to achieve spatial resolution of 1.6 mm (2.2×2.2×20 mm3 crystal) and 0.77 mm (1×1×20 mm3 crystal) at the center of FOV, respectively. The incorporation of 10 mm DOI resolution can help mitigate parallax error towards the edge of FOV. For both 2.2 mm and 1 mm crystal designs, the spatial resolution is around 3.2-3.5 mm at 5 cm away from the center. Finally, time-of-flight (TOF) helps in improving image quality, reduces the required number of iteration numbers and the scan time. The TOF effect was studied with 3 different time resolution settings (1 ns, 500 ps and 250 ps). With a TOF of 500 ps time resolution, we expect 3 mm diameter spheres where 5:1 activity concentration ratio will be detectable within 5 min achieving contrast to noise ratio (CNR) above 4.

Multi-Angle Snowflake Camera Instrument Handbook

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

Stuefer, Martin; Bailey, J.

2016-07-01

The Multi-Angle Snowflake Camera (MASC) takes 9- to 37-micron resolution stereographic photographs of free-falling hydrometers from three angles, while simultaneously measuring their fall speed. Information about hydrometeor size, shape orientation, and aspect ratio is derived from MASC photographs. The instrument consists of three commercial cameras separated by angles of 36º. Each camera field of view is aligned to have a common single focus point about 10 cm distant from the cameras. Two near-infrared emitter pairs are aligned with the camera’s field of view within a 10-angular ring and detect hydrometeor passage, with the lower emitters configured to trigger the MASCmore » cameras. The sensitive IR motion sensors are designed to filter out slow variations in ambient light. Fall speed is derived from successive triggers along the fall path. The camera exposure times are extremely short, in the range of 1/25,000th of a second, enabling the MASC to capture snowflake sizes ranging from 30 micrometers to 3 cm.« less

Shielding effects in the laser-generated copper plasma under reduced pressures of He atmosphere

NASA Astrophysics Data System (ADS)

Burger, M.; Pantić, D.; Nikolić, Z.; Djeniže, S.

2016-02-01

Irradiation of samples was performed with 6 ns, 1064 nm Nd:YAG laser. For an applied irradiance range (108-1010 W/cm2), the ablation process exhibits non-linear dependance. Ablated mass of the sample was directly determined using 100 ng resolution mass comparator after ablation under various pressures of helium. The ablation rates were dictated by plasma formation mechanisms as well as ambient conditions. However, the surrounding atmosphere did not significantly affect the value of threshold irradiance of about 2 ×109 W /cm2 for the onset of ablation mechanism change. This value is additionally verified via spectroscopic information from Cu I lines in the range from 0.4 to 1 μs after the laser pulse. Behaviour of spectral lines was monitored with respect to the laser pulse energy. Plasma diagnostics of axial electron density and excitation temperature distributions was performed under He pressure of 200 Torr. An influence of the possible shielding mechanisms responsible for the plasma absorption is discussed.

Dynamically downscaled climate simulations over North America: Methods, evaluation, and supporting documentation for users

USGS Publications Warehouse

Hostetler, S.W.; Alder, J.R.; Allan, A.M.

2011-01-01

We have completed an array of high-resolution simulations of present and future climate over Western North America (WNA) and Eastern North America (ENA) by dynamically downscaling global climate simulations using a regional climate model, RegCM3. The simulations are intended to provide long time series of internally consistent surface and atmospheric variables for use in climate-related research. In addition to providing high-resolution weather and climate data for the past, present, and future, we have developed an integrated data flow and methodology for processing, summarizing, viewing, and delivering the climate datasets to a wide range of potential users. Our simulations were run over 50- and 15-kilometer model grids in an attempt to capture more of the climatic detail associated with processes such as topographic forcing than can be captured by general circulation models (GCMs). The simulations were run using output from four GCMs. All simulations span the present (for example, 1968-1999), common periods of the future (2040-2069), and two simulations continuously cover 2010-2099. The trace gas concentrations in our simulations were the same as those of the GCMs: the IPCC 20th century time series for 1968-1999 and the A2 time series for simulations of the future. We demonstrate that RegCM3 is capable of producing present day annual and seasonal climatologies of air temperature and precipitation that are in good agreement with observations. Important features of the high-resolution climatology of temperature, precipitation, snow water equivalent (SWE), and soil moisture are consistently reproduced in all model runs over WNA and ENA. The simulations provide a potential range of future climate change for selected decades and display common patterns of the direction and magnitude of changes. As expected, there are some model to model differences that limit interpretability and give rise to uncertainties. Here, we provide background information about the GCMs and the RegCM3, a basic evaluation of the model output and examples of simulated future climate. We also provide information needed to access the web applications for visualizing and downloading the data, and give complete metadata that describe the variables in the datasets.

Low material budget floating strip Micromegas for ion transmission radiography

NASA Astrophysics Data System (ADS)

Bortfeldt, J.; Biebel, O.; Flierl, B.; Hertenberger, R.; Klitzner, F.; Lösel, Ph.; Magallanes, L.; Müller, R.; Parodi, K.; Schlüter, T.; Voss, B.; Zibell, A.

2017-02-01

Floating strip Micromegas are high-accuracy and discharge insensitive gaseous detectors, able to track single particles at fluxes of 7 MHz/cm2 with 100 μm resolution. We developed low-material-budget detectors with one-dimensional strip readout, suitable for tracking at highest particle rates as encountered in medical ion transmission radiography or inner tracker applications. Recently we additionally developed Kapton-based floating strip Micromegas with two-dimensional strip readout, featuring an overall thickness of 0.011 X0. These detectors were tested in high-rate proton and carbon-ion beams at the tandem accelerator in Garching and the Heidelberg Ion-Beam Therapy Center, operated with an optimized Ne:CF4 gas mixture. By coupling the Micromegas detectors to a new scintillator based range detector, ion transmission radiographies of PMMA and tissue-equivalent phantoms were acquired. The range detector with 18 layers is read out via wavelength shifting fibers, coupled to a multi-anode photomultiplier. We present the performance of the Micromegas detectors with respect to timing and single plane track reconstruction using the μTPC method. We discuss the range resolution of the scintillator range telescope and present the image reconstruction capabilities of the combined system.

Application of a broadly tunable SG-DBR QCL for multi-species trace gas spectroscopy.

PubMed

Diba, Abdou S; Xie, Feng; Gross, Barry; Hughes, Lawrence C; Zah, Chung-en; Moshary, Fred

2015-10-19

Feasibility of using a mid-Infrared tunable sampled-grating distributed Bragg reflectors quantum cascade laser for high resolution multicomponent trace gas spectroscopy is demonstrated. By controlling the driving currents to the front and back sections of the laser, we were able to tune a pulsed 4.55 µm laser over a frequency range a of 30 cm(-1) with high resolution, accuracy and repeatability. The laser was applied to absorption spectroscopy of ambient and reduced pressure (150 Torr) air in a 205 meters multi-pass Herriott cell, and by using standard LSQ fitting to a spectral database of these trace gases (HITRAN), the concentrations of nitrous oxide, carbon monoxide, and water vapor were retrieved.

Colors of active regions on comet 67P

NASA Astrophysics Data System (ADS)

Oklay, N.; Vincent, J.-B.; Sierks, H.; Besse, S.; Fornasier, S.; Barucci, M. A.; Lara, L.; Scholten, F.; Preusker, F.; Lazzarin, M.; Pajola, M.; La Forgia, F.

2015-10-01

The OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) scientific imager (Keller et al. 2007) is successfully delivering images of comet 67P/Churyumov-Gerasimenko from its both wide angle camera (WAC) and narrow angle camera (NAC) since ESA's spacecraft Rosetta's arrival to the comet. Both cameras are equipped with filters covering the wavelength range of about 200 nm to 1000 nm. The comet nucleus is mapped with different combination of the filters in resolutions up to 15 cm/px. Besides the determination of the surface morphology in great details (Thomas et al. 2015), such high resolution images provided us a mean to unambiguously link some activity in the coma to a series of pits on the nucleus surface (Vincent et al. 2015).

Single diode laser sensor for wide-range H2O temperature measurements.

PubMed

Gharavi, Mohammadreza; Buckley, Steven G

2004-04-01

A single diode laser absorption sensor (near 1477 nm) useful for simultaneous temperature and H2O concentration measurements is developed. The diode laser tunes approximately 1.2 cm(-1) over three H2O absorption transitions in each measurement. The line strengths of the transitions are measured over a temperature range from 468 to 977 K, based on high-resolution absorption measurements in a heated static cell. The results indicate that the selected transitions are suitable for sensitive temperature measurements in atmospheric pressure combustion systems using absorption line ratios. Comparing the results with HITRAN 96 data, it appears that these transitions will be sensitive over a wide range of temperatures (450-2000 K), suggesting applicability for combustion measurements.

Rovibrational photoionization dynamics of methyl and its isotopomers studied by high-resolution photoionization and photoelectron spectroscopy

NASA Astrophysics Data System (ADS)

Schulenburg, A. M.; Alcaraz, Ch.; Grassi, G.; Merkt, F.

2006-09-01

High-resolution photoionization and pulsed-field-ionization zero-kinetic-energy photoelectron spectra of CH3, CH2D, CHD2, and CD3 have been recorded in the vicinity of the first adiabatic ionization threshold following single-photon excitation from the ground neutral state using a narrow-bandwidth vacuum-ultraviolet laser. The radicals were produced from the precursor molecules methyl-bromide, methyl-iodide, dimethyl-thioether, acetone, and nitromethane by 193nm excimer photolysis in a quartz capillary and were subsequently cooled to a rotational temperature Trot≈30K in a supersonic expansion. Nitromethane was identified as a particularly suitable photolytic precursor of methyl for studies by photoionization and threshold photoelectron spectroscopy. Thanks to the cold rotational temperature reached in the supersonic expansion, the rotational structure of the threshold ionization spectra could be resolved, and the photoionization dynamics investigated. Rydberg series converging on excited rotational levels of CH3+ could be observed in the range of principal quantum number n =30-50, and both rotational autoionization and predissociation were identified as decay processes in the threshold region. The observed photoionization transitions can be understood in the realm of an orbital model for direct ionization but the intensity distributions can only be fully accounted for if the rotational channel interactions mediated by the quadrupole of the cation are considered. Improved values of the adiabatic ionization thresholds were derived for all isotopomers [CH3: 79356.2(15)cm-1, CH2D: 79338.8(15)cm-1, CHD2: 79319.1(15)cm-1, and CD3: 79296.4(15)cm-1].

High-Resolution Infrared Spectrum of Monoiodoacetylene Between 2000 and 3000 cm -1

NASA Astrophysics Data System (ADS)

Ahonen, Anne-Maaria; Ahonen, Tarmo; Alanko, Seppo

1998-09-01

The high-resolution infrared spectrum of monoiodoacetylene measured with a Bruker IFS 120 HR Fourier transform spectrometer in the spectral range of 2000-3000 cm-1has been studied in detail. The strongest bands observed in the wavenumber region investigated are the C-C stretching fundamental ν2(2034-2082 cm-1) and the accompanying hot bands of the types ν2+ νn- νn, wheren= 3, 4, or 5, associated with the lowest stretching statev3= 1 and with the low-lying bending statesv4= 1 andv5= 1, 2, respectively. The combination bands of the types ν2+ νn, wherenis as above, starting direct from the ground state have also been observed. In addition, the weak overtone band 2ν2(4081-4121 cm-1) has been measured to study the anharmonicity of the C-C stretching mode. The new, more accurate values for the ground state rotational constants have been derived by combining the ground state combination differences calculated from our IR data available in the present work as well as in our previous investigations concerning the HCCI molecule to the accurate MW transitions from the literature. The rotational structures of the overtone levelv2= 2 and the combination levelsv2=vn= 1, wherenis as above, have been investigated by analyzing the observed spectra with a model including various Fermi- andl-type resonances. As a result, the values for the harmonic frequency ω02and the anharmonicity constantsx22,x23,x24, andx25are determined.

Utilization of all Spectral Channels of IASI for the Retrieval of the Atmospheric State

NASA Astrophysics Data System (ADS)

Del Bianco, S.; Cortesi, U.; Carli, B.

2010-12-01

The retrieval of atmospheric state parameters from broadband measurements acquired by high spectral resolution sensors, such as the Infrared Atmospheric Sounding Interferometer (IASI) onboard the Meteorological Operational (MetOp) platform, generally requires to deal with a prohibitively large number of spectral elements available from a single observation (8461 samples in the case of IASI, covering the 645-2760 cm-1 range with a resolution of 0.5 cm-1 and a spectral sampling of 0.25 cm-1). Most inversion algorithms developed for both operational and scientific analysis of IASI spectra perform a reduction of the data - typically based on channel selection, super-channel clustering or Principal Component Analysis (PCA) techniques - in order to handle the high dimensionality of the problem. Accordingly, simultaneous processing of all IASI channels received relatively low attention. Here we prove the feasibility of a retrieval approach exploiting all spectral channels of IASI, to extract information on water vapor, temperature and ozone profiles. This multi-target retrieval removes the systematic errors due to interfering parameters and makes the channel selection no longer necessary. The challenging computation is made possible by the use of a coarse spectral grid for the forward model calculation and by the abatement of the associated modeling errors through the use of a variance-covariance matrix of the residuals that takes into account all the forward model errors.

Recent Improvement of Medical Optical Fibre Pressure and Temperature Sensors.

PubMed

Poeggel, Sven; Duraibabu, Dineshbabu; Kalli, Kyriacos; Leen, Gabriel; Dooly, Gerard; Lewis, Elfed; Kelly, Jimmy; Munroe, Maria

2015-07-13

This investigation describes a detailed analysis of the fabrication and testing of optical fibre pressure and temperature sensors (OFPTS). The optical sensor of this research is based on an extrinsic Fabry-Perot interferometer (EFPI) with integrated fibre Bragg grating (FBG) for simultaneous pressure and temperature measurements. The sensor is fabricated exclusively in glass and with a small diameter of 0.2 mm, making it suitable for volume-restricted bio-medical applications. Diaphragm shrinking techniques based on polishing, hydrofluoric (HF) acid and femtosecond (FS) laser micro-machining are described and analysed. The presented sensors were examined carefully and demonstrated a pressure sensitivity in the range of sp = 2-10 nm/kPa and a resolution of better than ΔP = 10 Pa protect (0.1 cm H2O). A static pressure test in 38 cm H2O shows no drift of the sensor in a six-day period. Additionally, a dynamic pressure analysis demonstrated that the OFPTS never exceeded a drift of more than 130 Pa (1.3 cm H2O) in a 12-h measurement, carried out in a cardiovascular simulator. The temperature sensitivity is given by k = 10.7 pm/K, which results in a temperature resolution of better than ΔT = 0.1 K. Since the temperature sensing element is placed close to the pressure sensing element, the pressure sensor is insensitive to temperature changes.

Recent Improvement of Medical Optical Fibre Pressure and Temperature Sensors

PubMed Central

Poeggel, Sven; Duraibabu, Dineshbabu; Kalli, Kyriacos; Leen, Gabriel; Dooly, Gerard; Lewis, Elfed; Kelly, Jimmy; Munroe, Maria

2015-01-01

This investigation describes a detailed analysis of the fabrication and testing of optical fibre pressure and temperature sensors (OFPTS). The optical sensor of this research is based on an extrinsic Fabry–Perot interferometer (EFPI) with integrated fibre Bragg grating (FBG) for simultaneous pressure and temperature measurements. The sensor is fabricated exclusively in glass and with a small diameter of 0.2 mm, making it suitable for volume-restricted bio-medical applications. Diaphragm shrinking techniques based on polishing, hydrofluoric (HF) acid and femtosecond (FS) laser micro-machining are described and analysed. The presented sensors were examined carefully and demonstrated a pressure sensitivity in the range of sp = 2–10 nmkPa and a resolution of better than ΔP = 10 Pa (0.1 cm H2O). A static pressure test in 38 cmH2O shows no drift of the sensor in a six-day period. Additionally, a dynamic pressure analysis demonstrated that the OFPTS never exceeded a drift of more than 130 Pa (1.3 cm H2O) in a 12-h measurement, carried out in a cardiovascular simulator. The temperature sensitivity is given by k=10.7 pmK, which results in a temperature resolution of better than ΔT = 0.1 K. Since the temperature sensing element is placed close to the pressure sensing element, the pressure sensor is insensitive to temperature changes. PMID:26184331

VUV Fourier-transform absorption study of the Lyman and Werner bands in D2

NASA Astrophysics Data System (ADS)

de Lange, Arno; Dickenson, Gareth D.; Salumbides, Edcel J.; Ubachs, Wim; de Oliveira, Nelson; Joyeux, Denis; Nahon, Laurent

2012-06-01

An extensive survey of the D2 absorption spectrum has been performed with the high-resolution VUV Fourier-transform spectrometer employing synchrotron radiation. The frequency range of 90 000-119 000 cm-1 covers the full depth of the potential wells of the B sideset{^1}{+u}{Σ}, B^' } sideset{^1}{+u}{Σ}, and C 1Πu electronic states up to the D(1s) + D(2ℓ) dissociation limit. Improved level energies of rovibrational levels have been determined up to respectively v = 51, v = 13, and v = 20. Highest resolution is achieved by probing absorption in a molecular gas jet with slit geometry, as well as in a liquid helium cooled static gas cell, resulting in line widths of ≈0.35 cm-1. Extended calibration methods are employed to extract line positions of D2 lines at absolute accuracies of 0.03 cm-1. The D 1Πu and B^' ' } sideset{^1}{+u}{Σ} electronic states correlate with the D(1s) + D(3ℓ) dissociation limit, but support a few vibrational levels below the second dissociation limit, respectively, v = 0-3 and v = 0-1, and are also included in the presented study. The complete set of resulting level energies is the most comprehensive and accurate data set for D2. The observations are compared with previous studies, both experimental and theoretical.

Gallium Arsenide detectors for X-ray and electron (beta particle) spectroscopy

NASA Astrophysics Data System (ADS)

Lioliou, G.; Barnett, A. M.

2016-11-01

Results characterizing GaAs p+-i-n+ mesa photodiodes with a 10 μm i layer for their spectral response under illumination of X-rays and beta particles are presented. A total of 22 devices, having diameters of 200 μm and 400 μm, were electrically characterized at room temperature. All devices showed comparable characteristics with a measured leakage current ranging from 4 nA/cm2 to 67 nA/cm2 at an internal electric field of 50 kV/cm. Their unintentionally doped i layers were found to be almost fully depleted at 0 V due to their low doping density. 55Fe X-ray spectra were obtained using one 200 μm diameter device and one 400 μm diameter device. The best energy resolution (FWHM at 5.9 keV) achieved was 625 eV using the 200 μm and 740 eV using the 400 μm diameter device, respectively. Noise analysis showed that the limiting factor for the energy resolution of the system was the dielectric noise; if this noise was eliminated by better design of the front end of the readout electronics, the achievable resolution would be 250 eV. 63Ni beta particle spectra obtained using the 200 μm diameter device showed the potential utility of these detectors for electron and beta particle detection. The development of semiconductor electron spectrometers is important particularly for space plasma physics; such devices may find use in future space missions to study the plasma environment of Jupiter and Europa and the predicted electron impact excitation of water vapor plumes from Europa hypothesized as a result of recent Hubble Space Telescope (HST) UV observations.

Development of the Double Etalon Fabry-Perot Interferometer for Determining Total and Tropospheric Ozone Concentrations

NASA Technical Reports Server (NTRS)

Cook, William

1999-01-01

Measuring and understanding the distribution of ozone through the lower levels of Earth's atmosphere are high priorities in global change and climate research. Of particular interest now is the global distribution of ozone in the upper troposphere and lower stratosphere. Global coverage of the stratospheric ozone is feasible only via remote sensing instruments on a space-based platform. And though extensive monitoring tropospheric ozone is possible using instruments flown aboard conventional aircraft, a space-based system would be significantly less costly and provide information over a much broader area and produce more uniform coverage. Here we describe the prototype of an instrument being developed to monitor, from an orbiting spacecraft, the ozone found in Earth's upper troposphere and lower stratosphere. Our new spectrometer is an infrared Fabry-Perot interferometer which uses two synchrounously tuned etalons: a high resolution narrow band device and a lower resolution broader band filtering etalon. The prototype is a scanning device making use of nearly collimated input radiation and a single element detector. As presently configured, it is capable of providing a resolution better than 0.07/cm with a spectral band width approximately 5/cm wide and centered at 1054.7/cm. For the future space-based emission device a modification of the the prototype was to be made to employ innovative circle-to-line detector optics, those developed or in development at UM/SPRL, and a focal plane array detector. These enhancements would enable a simultaneous recording of the entire spectral range of interest, but with simple detection electronics and a significant gain in signal-to-noise over that of the scanning version.

High-resolution Manometry and Globus: Comparison of Globus, Gastroesophageal Reflux Disease and Normal Controls Using High-resolution Manometry.

PubMed

Choi, Won Seok; Kim, Tae Wan; Kim, Ja Hyun; Lee, Sang Hyuk; Hur, Woon Je; Choe, Young Gil; Lee, Sang Hyuk; Park, Jung Ho; Sohn, Chong Il

2013-10-01

Globus is a foreign body sense in the throat without dysphagia, odynophagia, esophageal motility disorders, or gastroesophageal reflux. The etiology is unclear. Previous studies suggested that increased upper esophageal sphincter pressure, gastroesophageal reflux and hypertonicity of esophageal body were possible etiologies. This study was to quantify the upper esophageal sphincter (UES) pressure, contractile front velocity (CFV), proximal contractile integral (PCI), distal contractile integral (DCI) and transition zone (TZ) in patient with globus gastroesophageal reflux disease (GERD) without globus, and normal controls to suggest the correlation of specific high-resolution manometry (HRM) findings and globus. Fifty-seven globus patients, 24 GERD patients and 7 normal controls were studied with HRM since 2009. We reviewed the reports, and selected 5 swallowing plots suitable for analysis in each report, analyzed each individual plot with ManoView. The 5 parameters from each plot in 57 globus patients were compared with that of 24 GERD patients and 7 normal controls. There was no significant difference in the UES pressure, CFV, PCI and DCI. TZ (using 30 mmHg isobaric contour) in globus showed significant difference compared with normal controls and GERD patients. The median values of TZ were 4.26 cm (interquartile range [IQR], 2.30-5.85) in globus patients, 5.91 cm (IQR, 3.97-7.62) in GERD patients and 2.26 cm (IQR, 1.22-2.92) in normal controls (P = 0.001). HRM analysis suggested that UES pressure, CFV, PCI and DCI were not associated with globus. Instead increased length of TZ may be correlated with globus. Further study comparing HRM results in globus patients within larger population needs to confirm their correlation.

High-resolution Manometry and Globus: Comparison of Globus, Gastroesophageal Reflux Disease and Normal Controls Using High-resolution Manometry

PubMed Central

Choi, Won Seok; Kim, Tae Wan; Kim, Ja Hyun; Lee, Sang Hyuk; Hur, Woon Je; Choe, Young Gil; Lee, Sang Hyuk; Park, Jung Ho

2013-01-01

Background/Aims Globus is a foreign body sense in the throat without dysphagia, odynophagia, esophageal motility disorders, or gastroesophageal reflux. The etiology is unclear. Previous studies suggested that increased upper esophageal sphincter pressure, gastroesophageal reflux and hypertonicity of esophageal body were possible etiologies. This study was to quantify the upper esophageal sphincter (UES) pressure, contractile front velocity (CFV), proximal contractile integral (PCI), distal contractile integral (DCI) and transition zone (TZ) in patient with globus gastroesophageal reflux disease (GERD) without globus, and normal controls to suggest the correlation of specific high-resolution manometry (HRM) findings and globus. Methods Fifty-seven globus patients, 24 GERD patients and 7 normal controls were studied with HRM since 2009. We reviewed the reports, and selected 5 swallowing plots suitable for analysis in each report, analyzed each individual plot with ManoView. The 5 parameters from each plot in 57 globus patients were compared with that of 24 GERD patients and 7 normal controls. Results There was no significant difference in the UES pressure, CFV, PCI and DCI. TZ (using 30 mmHg isobaric contour) in globus showed significant difference compared with normal controls and GERD patients. The median values of TZ were 4.26 cm (interquartile range [IQR], 2.30-5.85) in globus patients, 5.91 cm (IQR, 3.97-7.62) in GERD patients and 2.26 cm (IQR, 1.22-2.92) in normal controls (P = 0.001). Conclusions HRM analysis suggested that UES pressure, CFV, PCI and DCI were not associated with globus. Instead increased length of TZ may be correlated with globus. Further study comparing HRM results in globus patients within larger population needs to confirm their correlation. PMID:24199007

Archaeological Feedback as a Research Methodology in Near-Surface Geophysics

NASA Astrophysics Data System (ADS)

Maillol, J.; Ortega-Ramírez, J.; Berard, B.

2005-05-01

A unique characteristic of archaeological geophysics is to present the researchers in applied geophysics with the opportunity to verify their interpretation of geophysical data through the direct observation of often extremely detailed excavations. This is usually known as archaeological feedback. Archaeological materials have been slowly buried over periods ranging from several hundreds to several thousands of years, undergoing natural sedimentary and soil-forming processes. Once excavated, archaeological features therefore constitute more realistic test subjects than the targets artifically buried in common geophysical test sites. We are presenting the outcome of several such verification tests aimed at clarifying issues in geometry and spatial resolution of ground penetrating radar (GPR) images. On the site of a Roman villa in SE Portugal 500 Mhz GPR images are shown to depict very accurately the position and geometry of partially excavated remains. In the Maya city of Palenque, Mexico, 900 Mhz data allows the depth of tombs and natural cavities to be determined with cm accuracy. The predicted lateral extent of the cavities is more difficult to match with the reality due to the cluttering caused by high frequency. In the rainforest of Western Africa, 500 MHz GPR was used to prospect for stone tool sites. When very careful positioning and high density data sampling is achieved, stones can be accurately located and retrieved at depths exceeding 1 m with maximum positioning errors of 12cm horizontally and 2 cm vertically. In more difficult data collection conditions however, errors in positioning are shown to actually largely exceed the predictions based on quantitative theoretical resolution considerations. Geophysics has long been recognized as a powerful tool for prospecting and characterizing archaeological sites. Reciprocally, these results show that archaeology is an unparalleled test environment for the assesment and development of high resolution geophysical methods.

Risk of inundation to coastal wetlands and soil organic carbon and organic nitrogen accounting in Louisiana, USA.

PubMed

Zhong, Biao; Xu, Y Jun

2011-10-01

Exceeding 1.2 million acres (4856 km(2)) since the 1930s, coastal wetland loss has been the most threatening environmental problem in Louisiana, United States. This study utilized high-resolution LiDAR (Light Detection and Ranging) and DEM (Digital Elevation Model) data sets to assess the risk of potential wetland loss due to future sea level rises, their spatial distribution, and the associated loss of soil organic carbon (SOC) and organic nitrogen (SON) estimated from the State Soil Geographic (STATSGO) Database and National Wetlands Inventory (NWI) digital data. Potential inundation areas were divided into five elevation scales: < 0 cm, 0-50 cm, 50-100 cm, 100-150 cm, and 150-200 cm above mean sea level. The study found that southeastern Louisiana on the Mississippi River Delta, specifically the Pontchartrain and Barataria Basins, are most vulnerable to sea-level rise induced inundation. Accordingly, approximately 42,264,600 t of SOC and 2,817,640 t of SON would be inundated by 2050 using an average wetland SOC density (203 t per hectare) for the inundation areas between 0 and 50 cm. The estimated annual SOC and SON loss from Louisiana's coast is 17% of annual organic carbon and 6-8% of annual organic nitrogen inputs from the Mississippi River.

Comparison of DSMs acquired by terrestrial laser scanning, UAV-based aerial images and ground-based optical images at the Super-Sauze landslide

NASA Astrophysics Data System (ADS)

Rothmund, Sabrina; Niethammer, Uwe; Walter, Marco; Joswig, Manfred

2013-04-01

In recent years, the high-resolution and multi-temporal 3D mapping of the Earth's surface using terrestrial laser scanning (TLS), ground-based optical images and especially low-cost UAV-based aerial images (Unmanned Aerial Vehicle) has grown in importance. This development resulted from the progressive technical improvement of the imaging systems and the freely available multi-view stereo (MVS) software packages. These different methods of data acquisition for the generation of accurate, high-resolution digital surface models (DSMs) were applied as part of an eight-week field campaign at the Super-Sauze landslide (South French Alps). An area of approximately 10,000 m² with long-term average displacement rates greater than 0.01 m/day has been investigated. The TLS-based point clouds were acquired at different viewpoints with an average point spacing between 10 to 40 mm and at different dates. On these days, more than 50 optical images were taken on points along a predefined line on the side part of the landslide by a low-cost digital compact camera. Additionally, aerial images were taken by a radio-controlled mini quad-rotor UAV equipped with another low-cost digital compact camera. The flight altitude ranged between 20 m and 250 m and produced a corresponding ground resolution between 0.6 cm and 7 cm. DGPS measurements were carried out as well in order to geo-reference and validate the point cloud data. To generate unscaled photogrammetric 3D point clouds from a disordered and tilted image set, we use the widespread open-source software package Bundler and PMVS2 (University of Washington). These multi-temporal DSMs are required on the one hand to determine the three-dimensional surface deformations and on the other hand it will be required for differential correction for orthophoto production. Drawing on the example of the acquired data at the Super-Sauze landslide, we demonstrate the potential but also the limitations of the photogrammetric point clouds. To determine the quality of the photogrammetric point cloud, these point clouds are compared with the TLS-based DSMs. The comparison shows that photogrammetric points accuracies are in the range of cm to dm, therefore don't reach the quality of the high-resolution TLS-based DSMs. Further, the validation of the photogrammetric point clouds reveals that some of them have internal curvature effects. The advantage of the photogrammetric 3D data acquisition is the use of low-cost equipment and less time-consuming data collection in the field. While the accuracy of the photogrammetric point clouds is not as high as TLS-based DSMs, the advantages of the former method are seen when applied in areas where dm-range is sufficient.

Predictive Factors of Headache Resolution After Chiari Type 1 Malformation Surgery.

PubMed

Grangeon, Lou; Puy, Laurent; Gilard, Vianney; Hebant, Benjamin; Langlois, Olivier; Derrey, Stephane; Gerardin, Emmanuel; Maltete, David; Guegan-Massardier, Evelyne; Magne, Nicolas

2018-02-01

Headache is the main and often isolated symptom of patients with Chiari type 1 malformation (CM1). Classically described as occipital and exacerbated by cough, headaches may be poorly characterized, making it difficult to establish CM1 as the underlying cause. Current guidelines for surgical posterior fossa decompression are undefined. The challenge is to distinguish headaches related to CM1 from headaches coincidentally coexisting with CM1. We aimed to determine predictive factors of headache resolution after surgery and applied to our cohort the Chiari Severity Index, a recently developed predictive prognostic score. This retrospective study enrolled 49 patients with CM1 and preoperative headache. Standardized telephone interviews regarding headaches before and after surgery were conducted by the same neurologist; magnetic resonance imaging morphometric analyses were performed by an independent neuroradiologist. Headache resolution was defined as ≥50% reduction in frequency of headache days. Preoperative factors of headache resolution after multivariate analysis were attack duration <5 minutes (P = 0.001), triggering by Valsalva maneuvers (P = 0.003), severe intensity of attack (P = 0.05), occipital location (P = 0.05), and greater number of headache days per month (P = 0.04). These characteristics are part of International Headache Society diagnostic criteria for headache attributed to CM1. No radiologic predictive factor was demonstrated. Postoperative improvement was inversely correlated with Chiari Severity Index. This study confirms the relevance of International Headache Society criteria to identify headaches related to CM1. We propose their systematic use in a preoperative questionnaire. Copyright © 2017 Elsevier Inc. All rights reserved.

Analysis of Atmospheric Trace Constituents from High Resolution Infrared Balloon-Borne and Ground-Based Solar Absorption Spectra

NASA Technical Reports Server (NTRS)

Goldman, A.; Murcray, F. J.; Rinsland, C. P.; Blatherwick, R. D.; Murcray, F. H.; Murcray, D. G.

1991-01-01

Recent results and ongoing studies of high resolution solar absorption spectra will be presented. The analysis of these spectra is aimed at the identification and quantification of trace constituents important in atmospheric chemistry of the stratosphere and upper troposphere. Analysis of balloon-borne and ground-based spectra obtained at 0.0025/ cm covering the 700-2200/ cm interval will be presented. Results from ground-based 0.02/ cm solar spectra, from several locations such as Denver, South Pole, M. Loa, and New Zealand will also be shown. The 0.0025/ cm spectra show many new spectroscopic features. The analysis of these spectra, along with corresponding laboratory spectra, improves the spectral line parameters, and thus the accuracy of trace constituents quantification. The combination of the recent balloon flights, with earlier flights data since 1978 at 0.02/ cm resolution, provides trends analysis of several stratospheric trace species. Results for COF2, F22, SF6, and other species will be presented. Analysis of several ground-based solar spectra provides trends for HCl, HF and other species. The retrieval methods used for total column density and altitude distribution for both ground-based and balloon-borne spectra will be presented. These are extended for the analysis of the ground-based spectra to be obtained by the high resolution interferometers of the Network for Detection of Stratospheric Change (NDSC). Progress or the University of Denver studies for the NDSC will be presented. This will include intercomparison of solar spectra and trace gases retrievals obtained from simultaneous scans by the high resolution (0.0025/ cm) interferometers of BRUKER and BOMEM.

Space Situational Awareness CubeSat Concept of Operations

DTIC Science & Technology

2011-12-01

range in altitude from 200 km to 1700 km with a large concentration of debris at 800 km. A large number of spacecraft perform communications and...collaboration between the USAF, the Royal Canadian Air Force (RAF) and the Smithsonian Institution Astrophysics Observatory has evolved dramatically with...6.7 μm Readout Resolution 8 bits Exposure Time 1 s Aperture 85 mm Optics F# 2.65 Dimension < 9.75x9.75x15 cm Mass < 1.83 Kg Output Data Rate < 50 kbp

Study of the High Resolution Spectrum of the S18O16O Molecule in the Hot 2ν2 + ν3 - ν2 Band

NASA Astrophysics Data System (ADS)

Ziatkova, A. G.; Gromova, O. V.; Ulenikov, O. N.

2018-05-01

The hot 2ν2 + ν3 - ν2 hybrid band of the S18O16O molecule is assigned in the range 1800-1900 cm-1 for the first time. The spectrum is analyzed based on the method of combination differences. 56 energy levels (Jmax = 15, {K}a^{max}=12 ) are determined based on the experimental data obtained. Rotational parameters of the (021) vibrational state are determined.

VizieR Online Data Catalog: Spectra of a Holmium in the near-UV. I. Ho I. (Al-Labady+, 2017)

NASA Astrophysics Data System (ADS)

Al-Labady, N.; Ozdalgic, B.; Er, A.; Guzelcimen, F.; Ozturk, I. K.; Kroger, S.; Kruzins, A.; Tamanis, M.; Ferber, R.; Basar, G.

2017-04-01

The high-resolution spectra of Holmium (Ho) were recorded with a Fourier Transform spectrometer IFS125 HR at the Laser Centre of the University of Latvia in Riga. Two Ho spectra were recorded, one with argon (Ar) as a buffer gas and one with neon (Ne). The spectra cover the ultraviolet spectral range from 25000 up to 31530cm-1, or 317 to 400nm, respectively. (1 data file).

The Utility of fMRI for Assessing and Predicting Individual Differences in Fatigue Vulnerability

DTIC Science & Technology

2010-06-15

field of view (FOV) = 25.6 cm, image matrix = 256 x 256. Next, a set of T1-weighted axial low -resolution anatomical images encompassing the whole...wide range of central nervous system disorders and medication effects ( Lowe & Rabbitt, 1998; Randall, Fleck, Shneerson & File, 2004). These tests are...fusiform gyrus (Figure 5E); 6) Brodmann area 19 (Figure 5F); and 7) the entire cerebellum (Figure 5G ). Figure 5. Axial (top row) and sagittal

High-resolution absorption measurements of NH3 at high temperatures: 500-2100 cm-1

NASA Astrophysics Data System (ADS)

Barton, Emma J.; Yurchenko, Sergei N.; Tennyson, Jonathan; Clausen, Sønnik; Fateev, Alexander

2015-12-01

High-resolution absorption spectra of NH3 in the region 500-2100 cm-1 at temperatures up to 1027 °C and approximately atmospheric pressure (1013±20 mbar) are measured. NH3 concentrations of 1000 ppm, 0.5% and 1% in volume fraction were used in the measurements. Spectra are recorded in high temperature gas flow cells using a Fourier Transform Infrared (FTIR) spectrometer at a nominal resolution of 0.09 cm-1. Measurements at 22.7 °C are compared to high-resolution cross sections available from the Pacific Northwest National Laboratory (PNNL). The higher temperature spectra are analysed by comparison to a variational line list, BYTe, and experimental energy levels determined using the MARVEL procedure. Approximately 2000 lines have been assigned, of which 851 are newly assigned to mainly hot bands involving vibrational states as high as v2=5.

Refractive Index Sensing with D-Shaped Plastic Optical Fibers for Chemical and Biochemical Applications

PubMed Central

Sequeira, Filipa; Duarte, Daniel; Bilro, Lúcia; Rudnitskaya, Alisa; Pesavento, Maria; Zeni, Luigi; Cennamo, Nunzio

2016-01-01

We report the optimization of the length of a D-shaped plastic optical fiber (POF) sensor for refractive index (RI) sensing from a numerical and experimental point of view. The sensing principle is based on total internal reflection (TIR). POFs with 1 mm in diameter were embedded in grooves, realized in planar supports with different lengths, and polished to remove the cladding and part of the core. All D-shaped POF sensors were tested using aqueous medium with different refractive indices (from 1.332 to 1.471) through intensity-based configuration. Results showed two different responses. Considering the refractive index (RI) range (1.33–1.39), the sensitivity and the resolution of the sensor were strongly dependent on the sensing region length. The highest sensitivity (resolution of 6.48 × 10−3 refractive index units, RIU) was obtained with 6 cm sensing length. In the RI range (1.41–1.47), the length of the sensing region was not a critical aspect to obtain the best resolution. These results enable the application of this optical platform for chemical and biochemical evanescent field sensing. The sensor production procedure is very simple, fast, and low-cost. PMID:27983608

Refractive Index Sensing with D-Shaped Plastic Optical Fibers for Chemical and Biochemical Applications.

PubMed

Sequeira, Filipa; Duarte, Daniel; Bilro, Lúcia; Rudnitskaya, Alisa; Pesavento, Maria; Zeni, Luigi; Cennamo, Nunzio

2016-12-13

We report the optimization of the length of a D-shaped plastic optical fiber (POF) sensor for refractive index (RI) sensing from a numerical and experimental point of view. The sensing principle is based on total internal reflection (TIR). POFs with 1 mm in diameter were embedded in grooves, realized in planar supports with different lengths, and polished to remove the cladding and part of the core. All D-shaped POF sensors were tested using aqueous medium with different refractive indices (from 1.332 to 1.471) through intensity-based configuration. Results showed two different responses. Considering the refractive index (RI) range (1.33-1.39), the sensitivity and the resolution of the sensor were strongly dependent on the sensing region length. The highest sensitivity (resolution of 6.48 × 10 -3 refractive index units, RIU) was obtained with 6 cm sensing length. In the RI range (1.41-1.47), the length of the sensing region was not a critical aspect to obtain the best resolution. These results enable the application of this optical platform for chemical and biochemical evanescent field sensing. The sensor production procedure is very simple, fast, and low-cost.

Swap intensified WDR CMOS module for I2/LWIR fusion

NASA Astrophysics Data System (ADS)

Ni, Yang; Noguier, Vincent

2015-05-01

The combination of high resolution visible-near-infrared low light sensor and moderate resolution uncooled thermal sensor provides an efficient way for multi-task night vision. Tremendous progress has been made on uncooled thermal sensors (a-Si, VOx, etc.). It's possible to make a miniature uncooled thermal camera module in a tiny 1cm3 cube with <1W power consumption. For silicon based solid-state low light CCD/CMOS sensors have observed also a constant progress in terms of readout noise, dark current, resolution and frame rate. In contrast to thermal sensing which is intrinsic day&night operational, the silicon based solid-state sensors are not yet capable to do the night vision performance required by defense and critical surveillance applications. Readout noise, dark current are 2 major obstacles. The low dynamic range at high sensitivity mode of silicon sensors is also an important limiting factor, which leads to recognition failure due to local or global saturations & blooming. In this context, the image intensifier based solution is still attractive for the following reasons: 1) high gain and ultra-low dark current; 2) wide dynamic range and 3) ultra-low power consumption. With high electron gain and ultra low dark current of image intensifier, the only requirement on the silicon image pickup device are resolution, dynamic range and power consumption. In this paper, we present a SWAP intensified Wide Dynamic Range CMOS module for night vision applications, especially for I2/LWIR fusion. This module is based on a dedicated CMOS image sensor using solar-cell mode photodiode logarithmic pixel design which covers a huge dynamic range (> 140dB) without saturation and blooming. The ultra-wide dynamic range image from this new generation logarithmic sensor can be used directly without any image processing and provide an instant light accommodation. The complete module is slightly bigger than a simple ANVIS format I2 tube with <500mW power consumption.

High-resolution synchrotron infrared spectroscopy of acrolein: The vibrational levels between 700 and 820 cm-1

NASA Astrophysics Data System (ADS)

McKellar, A. R. W.; Billinghurst, B. E.

2015-09-01

The weak combination bands ν12 + ν18 and ν17 + ν18 of trans-acrolein in the 700-760 cm-1 region are observed at high resolution (<0.001 cm-1) using spectra obtained at the Canadian Light Source synchrotron radiation facility. A detailed rotational analysis of the 121181 and 171181 upper states is made which includes the nearby perturbing states 185, 132181, and 131183. Taking the results of this 5-state fit, together with earlier results on lower lying vibrations, we now have experimental characterization for all 15 excited vibrational states of acrolein lying below 820 cm-1.

Spatial resolution limits for the isotropic-3D PET detector X’tal cube

NASA Astrophysics Data System (ADS)

Yoshida, Eiji; Tashima, Hideaki; Hirano, Yoshiyuki; Inadama, Naoko; Nishikido, Fumihiko; Murayama, Hideo; Yamaya, Taiga

2013-11-01

Positron emission tomography (PET) has become a popular imaging method in metabolism, neuroscience, and molecular imaging. For dedicated human brain and small animal PET scanners, high spatial resolution is needed to visualize small objects. To improve the spatial resolution, we are developing the X’tal cube, which is our new PET detector to achieve isotropic 3D positioning detectability. We have shown that the X’tal cube can achieve 1 mm3 uniform crystal identification performance with the Anger-type calculation even at the block edges. We plan to develop the X’tal cube with even smaller 3D grids for sub-millimeter crystal identification. In this work, we investigate spatial resolution of a PET scanner based on the X’tal cube using Monte Carlo simulations for predicting resolution performance in smaller 3D grids. For spatial resolution evaluation, a point source emitting 511 keV photons was simulated by GATE for all physical processes involved in emission and interaction of positrons. We simulated two types of animal PET scanners. The first PET scanner had a detector ring 14.6 cm in diameter composed of 18 detectors. The second PET scanner had a detector ring 7.8 cm in diameter composed of 12 detectors. After the GATE simulations, we converted the interacting 3D position information to digitalized positions for realistic segmented crystals. We simulated several X’tal cubes with cubic crystals from (0.5 mm)3 to (2 mm)3 in size. Also, for evaluating the effect of DOI resolution, we simulated several X’tal cubes with crystal thickness from (0.5 mm)3 to (9 mm)3. We showed that sub-millimeter spatial resolution was possible using cubic crystals smaller than (1.0 mm)3 even with the assumed physical processes. Also, the weighted average spatial resolutions of both PET scanners with (0.5 mm)3 cubic crystals were 0.53 mm (14.6 cm ring diameter) and 0.48 mm (7.8 cm ring diameter). For the 7.8 cm ring diameter, spatial resolution with 0.5×0.5×1.0 mm3 crystals was improved 39% relative to the (1 mm)3 cubic crystals. On the other hand, spatial resolution with (0.5 mm)3 cubic crystals was improved 47% relative to the (1 mm)3 cubic crystals. The X’tal cube promises better spatial resolution for the 3D crystal block with isotropic resolution.

Performance evaluation of the Biograph mCT Flow PET/CT system according to the NEMA NU2-2012 standard.

PubMed

Rausch, Ivo; Cal-González, Jacobo; Dapra, David; Gallowitsch, Hans Jürgen; Lind, Peter; Beyer, Thomas; Minear, Gregory

2015-12-01

The purpose of the study is to evaluate the physical performance of a Biograph mCT Flow 64-4R PET/CT system (Siemens Healthcare, Germany) and to compare clinical image quality in step-and-shoot (SS) and continuous table motion (CTM) acquisitions. The spatial resolution, sensitivity, count rate curves, and Image Quality (IQ) parameters following the National Electrical Manufactures Association (NEMA) NU2-2012 standard were evaluated. For resolution measurements, an (18)F point source inside a glass capillary tube was used. Sensitivity measurements were based on a 70-cm-long polyethylene tube, filled with 4.5 MBq of FDG. Scatter fraction and count rates were measured using a 70-cm-long polyethylene cylinder with a diameter of 20 cm and a line source (1.04 GBq of FDG) inserted axially into the cylinder 4.5 cm off-centered. A NEMA IQ phantom containing six spheres (10- to 37-mm diameter) was used for the evaluation of the image quality. First, a single-bed scan was acquired (NEMA standard), followed by a two-bed scan (4 min each) of the IQ phantom with the image plane containing the spheres centered in the overlap region of the two bed positions. In addition, a scan of the same region in CTM mode was performed with a table speed of 0.6 mm/s. Furthermore, two patient scans were performed in CTM and SS mode. Image contrasts and patient images were compared between SS and CTM acquisitions. Full Width Half Maximum (FWHM) of the spatial resolution ranged from 4.3 to 7.8 mm (radial distance 1 to 20 cm). The measured sensitivity was 9.6 kcps/MBq, both at the center of the FOV and 10 cm off-center. The measured noise equivalent count rate (NECR) peak was 185 kcps at 29.0 kBq/ml. The scatter fraction was 33.5 %. Image contrast recovery values (sphere-to-background of 8:1) were between 42 % (10-mm sphere) to 79 % (37-mm sphere). The background variability was between 2.1 and 5.3 % (SS) and between 2.4 and 6.9 % (CTM). No significant difference in image quality was observed between SS and CTM mode. The spatial resolution, sensitivity, scatter fraction, and count rates were in concordance with the published values for the predecessor system, the Biograph mCT. Contrast recovery values as well as image quality obtained in SS and CTM acquisition modes were similar.

Iterative reconstruction with boundary detection for carbon ion computed tomography

NASA Astrophysics Data System (ADS)

Shrestha, Deepak; Qin, Nan; Zhang, You; Kalantari, Faraz; Niu, Shanzhou; Jia, Xun; Pompos, Arnold; Jiang, Steve; Wang, Jing

2018-03-01

In heavy ion radiation therapy, improving the accuracy in range prediction of the ions inside the patient’s body has become essential. Accurate localization of the Bragg peak provides greater conformity of the tumor while sparing healthy tissues. We investigated the use of carbon ions directly for computed tomography (carbon CT) to create the relative stopping power map of a patient’s body. The Geant4 toolkit was used to perform a Monte Carlo simulation of the carbon ion trajectories, to study their lateral and angular deflections and the most likely paths, using a water phantom. Geant4 was used to create carbonCT projections of a contrast and spatial resolution phantom, with a cone beam of 430 MeV/u carbon ions. The contrast phantom consisted of cranial bone, lung material, and PMMA inserts while the spatial resolution phantom contained bone and lung material inserts with line pair (lp) densities ranging from 1.67 lp cm-1 through 5 lp cm-1. First, the positions of each carbon ion on the rear and front trackers were used for an approximate reconstruction of the phantom. The phantom boundary was extracted from this approximate reconstruction, by using the position as well as angle information from the four tracking detectors, resulting in the entry and exit locations of the individual ions on the phantom surface. Subsequent reconstruction was performed by the iterative algebraic reconstruction technique coupled with total variation minimization (ART-TV) assuming straight line trajectories for the ions inside the phantom. The influence of number of projections was studied with reconstruction from five different sets of projections: 15, 30, 45, 60 and 90. Additionally, the effect of number of ions on the image quality was investigated by reducing the number of ions/projection while keeping the total number of projections at 60. An estimation of carbon ion range using the carbonCT image resulted in improved range prediction compared to the range calculated using a calibration curve.

Hindered rotations probed by rare earths in crystals: Er3+ and Tm3+ in BaY2F8

NASA Astrophysics Data System (ADS)

Baraldi, A.; Buffagni, E.; Capelletti, R.; Mazzera, M.; Magnani, N.; Carini, G., Jr.; D'Angelo, G.

2009-10-01

The sharpness of absorption lines induced by crystal-field (CF) transitions of rare earths (RE) can be exploited to disclose the rotational structure usually hidden under the more common broad electronic absorptions. In the present work the effectiveness of such an approach is proved by the analysis of the fine structure (FS) accompanying the Er3+ and Tm3+ CF lines in BaY2F8 single crystals. Sequences of weak, very narrow (0.03-0.1cm-1) , closely spaced (˜0.2-0.8cm-1) lines were monitored in high-resolution (as fine as 0.01cm-1 ), low-temperature (9 K) absorption spectra in the 2000-24000cm-1 range. The FS covers a few cm-1 on both sides of the narrowest among the RE-CF lines and is tightly associated with them, as proved by the amplitude dependence on the RE concentration (in the 0.5-20at.% range) and by linear dichroism measurements. The FS lines vanishing at temperatures as low as 40-60 K and the close spacing suggest that they may be ascribed to the simultaneous excitation of both RE-CF electronic transition and hindered rotation (or libration) mode of RE3+-F- group. The attribution is supported both by the specific structure of the host matrix which allows some F- mobility and by the very small line spacing which is in excellent agreement with the RE3+-F- rotational constant (2B=0.39cm-1) . Complementary specific-heat measurements in the temperature range 1.5-25 K show that Er3+ -doped samples display contributions, in addition to the vibrational one of a pure sample, which scale with the Er3+ concentration. The extra specific heat is interpreted in terms of Schottky anomalies; that peaking at ˜17K accounts for electronic transitions between the lowest sublevels of the I415/2 ground manifold, in agreement with the CF spectroscopy results while those occurring below 3.5 K are consistent with level pairs separated by 0.55 and 0.36cm-1 , in agreement with the FS line spacing.

The CU mobile Solar Occultation Flux instrument: structure functions and emission rates of NH3, NO2 and C2H6

NASA Astrophysics Data System (ADS)

Kille, Natalie; Baidar, Sunil; Handley, Philip; Ortega, Ivan; Sinreich, Roman; Cooper, Owen R.; Hase, Frank; Hannigan, James W.; Pfister, Gabriele; Volkamer, Rainer

2017-02-01

We describe the University of Colorado mobile Solar Occultation Flux instrument (CU mobile SOF). The instrument consists of a digital mobile solar tracker that is coupled to a Fourier transform spectrometer (FTS) of 0.5 cm-1 resolution and a UV-visible spectrometer (UV-vis) of 0.55 nm resolution. The instrument is used to simultaneously measure the absorption of ammonia (NH3), ethane (C2H6) and nitrogen dioxide (NO2) along the direct solar beam from a moving laboratory. These direct-sun observations provide high photon flux and enable measurements of vertical column densities (VCDs) with geometric air mass factors, high temporal resolution of 2 s and spatial resolution of 5-19 m. It is shown that the instrument line shape (ILS) of the FTS is independent of the azimuth and elevation angle pointing of the solar tracker. Further, collocated measurements next to a high-resolution FTS at the National Center for Atmospheric Research (HR-NCAR-FTS) show that the CU mobile SOF measurements of NH3 and C2H6 are precise and accurate; the VCD error at high signal to noise ratio is 2-7 %. During the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) from 21 July to 3 September 2014 in Colorado, the CU mobile SOF instrument measured median (minimum, maximum) VCDs of 4.3 (0.5, 45) × 1016 molecules cm-2 NH3, 0.30 (0.06, 2.23) × 1016 molecules cm-2 NO2 and 3.5 (1.5, 7.7) × 1016 molecules cm-2 C2H6. All gases were detected in larger 95 % of the spectra recorded in urban, semi-polluted rural and remote rural areas of the Colorado Front Range. We calculate structure functions based on VCDs, which describe the variability of a gas column over distance, and find the largest variability for NH3. The structure functions suggest that currently available satellites resolve about 10 % of the observed NH3 and NO2 VCD variability in the study area. We further quantify the trace gas emission fluxes of NH3 and C2H6 and production rates of NO2 from concentrated animal feeding operations (CAFO) using the mass balance method, i.e., the closed-loop vector integral of the VCD times wind speed along the drive track. Excellent reproducibility is found for NH3 fluxes and also, to a lesser extent, NO2 production rates on 2 consecutive days; for C2H6 the fluxes are affected by variable upwind conditions. Average emission factors were 12.0 and 11.4 gNH3 h-1 head-1 at 30 °C for feedlots with a combined capacity for ˜ 54 000 cattle and a dairy farm of ˜ 7400 cattle; the pooled rate of 11.8 ± 2.0 gNH3 h-1 head-1 is compatible with the upper range of literature values. At this emission rate the NH3 source from cattle in Weld County, CO (535 766 cattle), could be underestimated by a factor of 2-10. CAFO soils are found to be a significant source of NOx. The NOx source accounts for ˜ 1.2 % of the N flux in NH3 and has the potential to add ˜ 10 % to the overall NOx emissions in Weld County and double the NOx source in remote areas. This potential of CAFO to influence ambient NOx concentrations on the regional scale is relevant because O3 formation is NOx sensitive in the Colorado Front Range. Emissions of NH3 and NOx are relevant for the photochemical O3 and secondary aerosol formation.

High-resolution absorption measurements of NH3 at high temperatures: 2100-5500 cm-1

NASA Astrophysics Data System (ADS)

Barton, Emma J.; Yurchenko, Sergei N.; Tennyson, Jonathan; Clausen, Sønnik; Fateev, Alexander

2017-03-01

High-resolution absorption spectra of NH3 in the region 2100-5500 cm-1 at 1027 °C and approximately atmospheric pressure (1045±3 mbar) are measured. An NH3 concentration of 10% in volume fraction is used in the measurements. Spectra are recorded in a high-temperature gas-flow cell using a Fourier Transform Infrared (FTIR) spectrometer at a nominal resolution of 0.09 cm-1. The spectra are analysed by comparison to a variational line list, BYTe, and experimental energy levels determined using the MARVEL procedure. 2308 lines have been assigned to 45 different bands, of which 1755 and 15 have been assigned or observed for the first time in this work.

HIGH-RESOLUTION FOURIER TRANSFORM INFRARED SPECTRUM OF THE ν2 + ν12 BAND OF ETHYLENE (12C2H4)

NASA Astrophysics Data System (ADS)

Lebron, G. B.; Tan, T. L.

2013-09-01

The high-resolution Fourier transform infrared absorption spectrum of the ν2 + ν12 combination band of normal ethylene (12C2H4) in the 3050-3105 cm-1 region was recorded at a resolution of 0.0063 cm-1 and at an ambient temperature of 296 K. Upper state rovibrational analysis was carried out using a standard Watson's Hamiltonian in asymmetric reduction in Ir representation. The band center, rotational constants and centrifugal distortion constants up to quartic terms of the upper ν2 + ν12 = 1 state were determined from the final fit that included 102 infrared transitions. The root-mean-square deviation of the fit was 0.000729 cm-1.

High-Resolution FTIR Spectrum of the ν 5Band of HCOOD

NASA Astrophysics Data System (ADS)

Goh, K. L.; Ong, P. P.; Tan, T. L.; Teo, H. H.; Wang, W. F.

1998-10-01

The high-resolution Fourier transform infrared spectrum of HCOOD has been measured in the ν5region between 1120 and 1220 cm-1with a resolution of 0.004 cm-1. As expected for an in-plane vibrational fundamental mode, the ν5band is a hybrid band consisting of botha-type andb-type transitions. Using the Watson'sA-reduced Hamiltonian in theIrrepresentation, 1943 infrared transitions have been assigned and fitted to give 12 rovibrational constants for thev5= 1 state. The ν5band is primarilyAtype with a band center at 1177.09378 ± 0.00002 cm-1. It is found that ν5is slightly perturbed by the nearby 2ν7. About 90 perturbed transitions were identified.

Surface phonons on Bi2Sr2CaCu2O8+δ

NASA Astrophysics Data System (ADS)

Phelps, R. B.; Akavoor, P.; Kesmodel, L. L.; Demuth, J. E.; Mitzi, D. B.

1993-11-01

We report measurements of surface optical phonons on Bi2Sr2CaCu2O8+δ with high-resolution electron-energy-loss spectroscopy (HREELS). In addition to peaks near 50 and 80 meV (403 and 645 cm-1), which have been previously observed, our loss spectra exhibit a peak at 26 meV (210 cm-1). Loss spectra were measured at temperatures from 45 to 146 K, and the temperature dependence of the peaks was found to be weak. The 50 and 80 meV peaks shift to lower frequency by ~1.5 meV over this temperature range. All three peaks are attributed to surface optical phonons. The identification of particular bulk modes corresponding to the surface modes observed with HREELS is discussed.

Large area silicon drift detectors for x-rays -- New results

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

Iwanczyk, J.S.; Patt, B.E.; Tull, C.R.

Large area silicon drift detectors, consisting of 8 mm and 12 mm diameter hexagons, were fabricated on 0.35 mm thick high resistivity n-type silicon. An external FET and a low-noise charge sensitive preamplifier were used for testing the prototype detectors. The detector performance was measured in the range 75 to 25 C using Peltier cooling, and from 0.125 to 6 {micro}s amplifier shaping time. Measured energy resolutions were 159 eV FWHM and 263 eV FWHM for the 0.5 cm{sup 2} and 1 cm{sup 2} detectors, respectively (at 5.9 keV, {minus}75 C, 6 {micro}s shaping time). The uniformity of the detectormore » response over the entire active area (measured using 560 nm light) was < 0.5%.« less

Evidence for disequilibrium of ortho and para hydrogen on Jupiter from Voyager IRIS measurements

NASA Technical Reports Server (NTRS)

Conrath, B. J.; Gierasch, P. J.

1983-01-01

Preliminary results of an analysis of the ortho state/para state ratio (parallel/antiparallel) for molecular H2 in the Jovian atmosphere using Voyager IR spectrometer (IRIS) data are reported. The study was undertaken to expand the understanding of the thermodynamics of a predominantly H2 atmosphere, which takes about 100 million sec to reach equilibrium. IRIS data provided 4.3/cm resolution in the 300-700/cm spectral range dominated by H2 lines. Approximately 600 spectra were examined to detect any disequilibrium between the hydrogen species. The results indicate that the ortho-para ratio is not in an equilibrium state in the upper Jovian troposphere. A thorough mapping of the para-state molecules in the upper atmosphere could therefore aid in mapping the atmospheric flowfield.

Ensonifying Change: Repeat Ultra-High-Resolution Surveys in Monterey Canyon before and after Passage of a Turbidity Current

NASA Astrophysics Data System (ADS)

Wolfson-Schwehr, M.; Paull, C. K.; Caress, D. W.; Carvajal, C.; Thomas, H. J.; Maier, K. L.; Parsons, D. R.; Simmons, S.

2017-12-01

Turbidity currents are one of the primary means of global sediment transport, yet our understanding of how they interact with the seafloor is hindered by the limited number of direct measurements. The Coordinated Canyon Experiment (CCE; October 2015 - April 2017) has made great strides in addressing this issue by providing direct measurements of turbidity currents and detailed observations of the resulting seafloor change in Monterey Canyon, offshore California. Here we focus on a section of the canyon at 1850-m water depth, where a Seafloor Instrument Node (SIN) recorded passage of three turbidity currents using a range of sensors, including three upward-looking acoustic Doppler current profilers. The fastest event at this site had a maximum velocity of 2.8 m/s, and dragged the 430-Kg SIN 26 m down-canyon. Repeat mapping surveys were conducted four times during the CCE, utilizing a prototype ultra-high-resolution mapping system mounted on the ROV Doc Ricketts. The survey platform hosts a 400-kHz Reson 7125 multibeam sonar, a 3DatDepth SL1 subsea LiDAR, two stereo color cameras, and a Kearfott SeaDevil INS. At a survey altitude of 2.5 m above the bed, the system provides remarkable 5-cm resolution multibeam bathymetry, 1-cm resolution LiDAR bathymetry, and 2-mm resolution photomosaics, and can cover a 100-m2 survey area. Surveys of the SIN site prior to and after the fastest event show areas of net deposition/erosion of 60 cm and 20 cm, respectively. Net deposition occurred in the topographic lows between bedforms, while erosion was focused on the bedform crests. At the end of the experiment, transects of sediment cores were taken by ROV within areas of net deposition. The cores show a variety of sedimentary facies, including muds, sands, gravel, and organic rich layers. Gravel layers have sharp erosive bases. The repeat surveys document the dynamic nature of flute-like scours as the flow events erode and deposit material along the canyon floor, as well as the evolution of scours between events. While the scours may represent a small component of sediment transport within the canyon, their multi-generational structure indicates a complex interaction of scour processes along the canyon bed. These data provide a new means to understanding the detailed changes in canyon floor morphology and sedimentology at the event scale.

Modeling and measurement of the detector presampling MTF of a variable resolution x-ray CT scanner

PubMed Central

Melnyk, Roman; DiBianca, Frank A.

2007-01-01

The detector presampling MTF of a 576-channel variable resolution x-ray (VRX) CT scanner was evaluated in this study. The scanner employs a VRX detector, which provides increased spatial resolution by matching the scanner’s field of view (FOV) to the size of an object being imaged. Because spatial resolution is the parameter the scanner promises to improve, the evaluation of this resolution is important. The scanner’s pre-reconstruction spatial resolution, represented by the detector presampling MTF, was evaluated using both modeling (Monte Carlo simulation) and measurement (the moving slit method). The theoretical results show the increase in the cutoff frequency of the detector presampling MTF from 1.39 cy/mm to 43.38 cy/mm as the FOV of the VRX CT scanner decreases from 32 cm to 1 cm. The experimental results are in reasonable agreement with the theoretical data. Some discrepancies between the measured and the modeled detector presampling MTFs can be explained by the limitations of the model. At small FOVs (1–8 cm), the MTF measurements were limited by the size of the focal spot. The obtained results are important for further development of the VRX CT scanner. PMID:17369872

Electrical and photovoltaic properties of residue-free MoS2 thin films by liquid exfoliation method

NASA Astrophysics Data System (ADS)

Kyo Lee, Seung; Chu, Dongil; Song, Da Ye; Pak, Sang Woo; Kim, Eun Kyu

2017-05-01

Molybdenum disulfide (MoS2) film fabricated by a liquid exfoliation method has significant potential for various applications, because of its advantages of mass production and low-temperature processes. In this study, residue-free MoS2 thin films were formed during the liquid exfoliation process and their electrical properties were characterized with an interdigitated electrode. Then, the MoS2 film thickness could be controlled by centrifuge condition in the range of 20 ˜ 40 nm, and its carrier concentration and mobility were measured at about 7.36 × 1016 cm-3 and 4.67 cm2 V-1 s-1, respectively. Detailed analysis on the films was done by atomic force microscopy, Raman spectroscopy, and high-resolution transmission electron microscopy measurements for verifying the film quality. For application of the photovoltaic device, a Au/MoS2/silicon/In junction structure was fabricated, which then showed power conversion efficiency of 1.01% under illumination of 100 mW cm-2.

NOSD-1000, the high-temperature nitrous oxide spectroscopic databank

NASA Astrophysics Data System (ADS)

Tashkun, S. A.; Perevalov, V. I.; Lavrentieva, N. N.

2016-07-01

We present a high-temperature version, NOSD-1000, of the nitrous oxide spectroscopic databank. The databank contains the line parameters (positions, intensities, air- and self-broadened half-widths and coefficients of temperature dependence of air- and self-broadened half-widths) of the most abundant isotopologue 14N216O of the nitrous oxide molecule. The reference temperature is Tref=1000 K and the intensity cutoff is Icut=10-25 cm-1/(molecule cm-2). More than 1.4 million lines covering the 260-8310 cm-1 spectral range are included in NOSD-1000. The databank has been generated within the framework of the method of effective operators and based on the global fittings of spectroscopic parameters (parameters of the effective Hamiltonian and effective dipole moment operators) to observed data collected from the literature. Line-by-line simulation of a medium-resolution high-temperature (T=873 K) spectrum has been performed in order to validate the databank. NOSD-1000 is freely accessible via the Internet.

A refined gravity model from Lageos /GEM-L2/

NASA Technical Reports Server (NTRS)

Lerch, F. J.; Klosko, S. M.; Patel, G. B.

1982-01-01

Lageos satellite laser ranging (SLR) data taken over a 2.5 yr period were employed to develop the Goddard Earth Model GEM-L2, a refined gravity field model. Additional data was gathered with 30 other satellites, resulting in spherical harmonics through degree and order 20, based on over 600,000 measurements. The Lageos data was accurate down to 10 cm, after which the GEM 9 data were used to make adjustments past order 7. The resolution of long wavelength activity, through degree and order 4, was made possible by the Lageos data. The GEM-L2 model features a 20 x 20 geopotential, tracking station coordinates (20), 5-day polar motion and A1-UT1 values, and a GM value of 398,600.607 cu km/sq sec. The accuracy of station positioning has been raised to within 6 cm total position globally and within 1.8 cm in baselines. It is concluded that SLR is useful for measuring tectonic plate motions and inter-plate deformations.

Cold Collisions in a Molecular Synchrotron

NASA Astrophysics Data System (ADS)

van der Poel, Aernout P. P.; Zieger, Peter C.; van de Meerakker, Sebastiaan Y. T.; Loreau, Jérôme; van der Avoird, Ad; Bethlem, Hendrick L.

2018-01-01

We study collisions between neutral, deuterated ammonia molecules (ND3 ) stored in a 50 cm diameter synchrotron and argon atoms in copropagating supersonic beams. The advantages of using a synchrotron in collision studies are twofold: (i) By storing ammonia molecules many round-trips, the sensitivity to collisions is greatly enhanced; (ii) the collision partners move in the same direction as the stored molecules, resulting in low collision energies. We tune the collision energy in three different ways: by varying the velocity of the stored ammonia packets, by varying the temperature of the pulsed valve that releases the argon atoms, and by varying the timing between the supersonic argon beam and the stored ammonia packets. These give consistent results. We determine the relative, total, integrated cross section for ND3+Ar collisions in the energy range of 40 - 140 cm-1 , with a resolution of 5 - 10 cm-1 and an uncertainty of 7%-15%. Our measurements are in good agreement with theoretical scattering calculations.

Structural properties of H-implanted InP crystals

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

Bocchi, C.; Franzosi, P.; Lazzarini, L.

1993-07-01

H has been implanted in InP crystals at the energy E [equals] 100 keV and at different doses ranging from [sigma] [equals] 1 x 10[sup 13] to [sigma] [equals] 5 x 10[sup 16] cm[sup [minus]2]. The depth dependence of the elastic lattice strain has been investigated by high resolution X-ray diffractometry. The implantation produces a lattice dilation. The strain increases with increasing depth, reaches the maximum at about 0.75 [mu]m, and then decreases rapidly; moreover the maximum strain is proportional to the dose. No extended crystal defects have been detected by transmission electron microscopy up to [sigma] <1 x 10[supmore » 16] cm[sup [minus]2] a buried amorphous layer 28 nm in thickness has been observed at the same depth where the strain is maximum. The thickness of the amorphous layer increases by further increasing the dose and reaches a value of about 0.18 [mu]m for [sigma] [equals] 5 x 10[sup 16] cm[sup [minus]2].« less

Tunable diode laser measurements of HO2NO2 absorption coefficients near 12.5 microns

NASA Technical Reports Server (NTRS)

May, R. D.; Molina, L. T.; Webster, C. R.

1988-01-01

A tunable diode laser spectrometer has been used to measure absorption coefficients of peroxynitric acid (HO2NO2) near the 803/cm Q branch. HO2NO2 concentrations in a low-pressure flowing gas mixture were determined from chemical titration procedures and UV absorption spectroscopy. The diode laser measured absorption coefficients, at a spectral resolution of better than 0.001/cm, are about 10 percent larger than previous Fourier transform infrared measurements made at a spectral resolution of 0.06/cm.

Photon-Counting Laser Altimeters: Aircraft Demonstration and Future Application to Globally Contiguous Spaceborne Topographic Mapping

NASA Astrophysics Data System (ADS)

Degnan, J. J.

2002-05-01

We have recently demonstrated a scanning, photon-counting, laser altimeter, which is capable of daylight operations from aircraft cruise altitudes. The instrument measures the times-of-flight of individual photons to deduce the distances between the instrument reference and points on the underlying terrain from which the arriving photons were reflected. By imaging the terrain onto a highly pixellated detector followed by a multi-channel timing receiver, one can make multiple spatially-resolved measurements to the surface within a single laser pulse. The horizontal spatial resolution is limited by the optical projection of a single pixel onto the surface. In short, a 3D image of the terrain within the laser ground spot is obtained on each laser fire, assuming at least one signal photon is recorded by each pixel.. In test flights, a prototype airborne system has successfully recorded few kHz rate, single photon returns from clouds, soils, man-made objects, vegetation, and water surfaces at mid-day under conditions of maximum solar illumination. The system has also demonstrated a capability to resolve volumetrically distributed targets, such as tree canopies, and has performed wave height measurements and shallow water bathymetry over the Chesapeake Bay and Atlantic Ocean. The signal photons were reliably extracted from the solar noise background using an optimized Post-Detection Poisson Filter. The passively Q-switched microchip Nd:YAG laser transmitter measures only 2.25 mm in length and is pumped by a single 1.2 Watt laser diode. The output is frequency-doubled to take advantage of higher detector counting efficiencies and narrower spectral filters available at 532 nm. The transmitter produces a few microjoules of green energy in a subnanosecond pulse at several kilohertz rates. The illuminated ground area is imaged by a 14 cm diameter, diffraction-limited, off-axis telescope onto a segmented anode photomultiplier with up to 16 pixels (4 x4). Each anode segment is input to one channel of "fine" range receiver (5 cm detector-limited resolution), which records the times-of-flight of the individual photons. A parallel "coarse" receiver provides a lower resolution (>75 cm) histogram of atmospheric scatterers between the aircraft and ground and centers the "fine" receiver gate on the last set of returns, permitting the fine receiver to lock onto ground features with no a priori range knowledge. Many scientists have expressed a desire for globally contiguous maps of planetary bodies with few meter horizontal spatial resolutions and decimeter vertical resolutions. By sequentially overcoming various technical hurdles to globally contiguous mapping from space, we are led to a conceptual point design for a spaceborne, 3D imaging lidar, which utilizes low energy, high repetition rate lasers, photon-counting detector arrays, multi-channel timing receivers, and a unique optical scanner.

High-resolution FTIR spectroscopy of the ν7 and ν8 bands of 1-phosphapropyne

NASA Astrophysics Data System (ADS)

Bane, Michael K.; Jones, Cameron; Choong, Sam L.; Thompson, Christopher D.; Godfrey, Peter D.; Appadoo, Dominique R. T.; McNaughton, Don

2012-05-01

1-Phosphapropyne has been prepared and high-resolution (0.001 cm-1) spectra have been recorded on the far-infrared beamline at the Australian synchrotron between 1500-700 cm-1 and 400-50 cm-1. Ro-vibrational transitions of the ν8 (308 cm-1) and ν7 (1006 cm-1) fundamentals as well as the 2ν8±2←v8±1 and 2ν80←v8±1 hot-bands have been assigned, and rotational, centrifugal distortion and Coriolis interaction parameters determined. The 2ν8±2←v8±1 hot-band is an example of a particularly complex E ← E transition, for which both states are strongly Coriolis and l(2,2) coupled.

Observations of transitional tidal boundary layers and their impact on sediment transport in the Great Bay, NH

NASA Astrophysics Data System (ADS)

Koetje, K. M.; Foster, D. L.; Lippmann, T. C.

2017-12-01

Observations of the vertical structure of tidal flows obtained in 2016 and 2017 in the Great Bay Estuary, NH show evidence of transitional tidal boundary layers at deployment locations on shallow mudflats. High-resolution bottom boundary layer currents, hydrography, turbidity, and bed characteristics were observed with an acoustic Doppler current profiler (ADCP), an acoustic Doppler velocimeter (ADV), conductivity-depth-temperature (CTD) sensors, optical backscatter sensors, multibeam bathymetric surveys, and sediment grab samples and cores. Over the 2.5 m tidal range and at water depths ranging from 0.3 m to 1.5 m at mean lower low water, peak flows ranged from 10 cm/s to 30 cm/s and were primarily driven by the tides. A downward-looking ADCP captured the velocity profile over the lowest 1 m of the water column. Results consistently show a dual-log layer system, with evidence of a lower layer within 15 cm of the bed, another layer above approximately 30 cm from the bed, and a transitional region where the flow field rotates between that the two layers that can be as much as 180 degrees out of phase. CTD casts collected over a complete tidal cycle suggest that the weak thermohaline stratification is not responsible for development of the two layers. On the other hand, acoustic and optical backscatter measurements show spatial and temporal variability in suspended sediments that are dependant on tidal phase. Current work includes an examination of the relationship between sediment concentrations in the water column and velocity profile characteristics, along with an effort to quantify the impact of rotation and dual-log layers on bed stress.

Excitation of Molecular Hydrogen in the Orion Bar Photodissociation Region from a Deep Near-infrared IGRINS Spectrum

NASA Astrophysics Data System (ADS)

Kaplan, Kyle F.; Dinerstein, Harriet L.; Oh, Heeyoung; Mace, Gregory N.; Kim, Hwihyun; Sokal, Kimberly R.; Pavel, Michael D.; Lee, Sungho; Pak, Soojong; Park, Chan; Sok Oh, Jae; Jaffe, Daniel T.

2017-04-01

We present a deep near-infrared spectrum of the Orion Bar Photodissociation Region (PDR) taken with the Immersion Grating INfrared Spectrometer (IGRINS) on the 2.7 m telescope at the McDonald Observatory. IGRINS has high spectral resolution (R˜ {{45,000}}) and instantaneous broad wavelength coverage (1.45-2.45 μm), enabling us to detect 87 emission lines from rovibrationally excited molecular hydrogen (H2) that arise from transitions out of 69 upper rovibration levels of the electronic ground state. These levels cover a large range of rotational and vibrational quantum numbers and excitation energies, making them excellent probes of the excitation mechanisms of H2 and physical conditions within the PDR. The Orion Bar PDR is thought to consist of cooler high density clumps or filaments (T=50{--}250 K, {n}H={10}5{--}{10}7 cm-3) embedded in a warmer lower density medium (T=250{--}1000 K, {n}H={10}4{--}{10}5 cm-3). We fit a grid of constant temperature and density Cloudy models, which recreate the observed H2 level populations well, to constrain the temperature to a range of 600-650 K and the density to {n}H=2.5× {10}3{--}{10}4 cm-3. The best-fit model gives T = 625 K and {n}H=5× {10}3 cm-3. This well-constrained warm temperature is consistent with kinetic temperatures found by other studies for the Orion Bar’s lower density medium. However, the range of densities well fit by the model grid is marginally lower than those reported by other studies. We could be observing lower density gas than the surrounding medium, or perhaps a density-sensitive parameter in our models is not properly estimated.

High-resolution synchrotron infrared spectroscopy of thiophosgene: The ν1, ν5, 2ν4, and ν2 + 2ν6 bands

NASA Astrophysics Data System (ADS)

McKellar, A. R. W.; Billinghurst, B. E.

2015-09-01

Thiophosgene (Cl2CS) is a favorite model system for studies of photophysics, vibrational dynamics, and intersystem interactions. But its infrared spectra tend to be very congested due to hot bands and multiple isotopic species. This paper reports the first detailed study of the ν1 (∼1139 cm-1) and ν5 (∼820 cm-1) fundamental bands for the two most abundant isotopologues, 35Cl2CS and 35Cl37ClCS, based on spectra with a resolution of about 0.001 cm-1 obtained at the Canadian Light Source far-infrared beamline using synchrotron radiation and a Bruker IFS125 Fourier transform spectrometer. The 2ν4 (∼942 cm-1) and ν2 + 2ν6 (∼1104 cm-1) bands are also studied here, but the ν2 + ν6 band (∼795 cm-1) resisted full analysis.

Effects of viscosity and volume on the patterns of esophageal motility in healthy adults using high-resolution manometry.

PubMed

Park, J H; Lee, H; Rhee, P-L; Park, J H

2015-01-01

The purpose of this study was to determine the effects of age, sex, body mass index (BMI), viscosity, and volume on esophageal motility using high-resolution manometry (HRM). Manometric studies were performed on 60 asymptomatic volunteers (27 men and 33 women, age: 19-56 years) while in a supine position. Manometric protocol included 10 water swallows (5 cc), 10 jelly swallows (5 cc), and 1 water swallow (20 cc). Evaluation of HRM parameters including length of proximal pressure trough (PPT length), distal latency (DL), contractile front velocity (CFV), distal contractile integral (DCI), and 4-second integrated relaxation pressure (IRP) was performed using MATLAB. Significant differences were noted in median IRP between water 5 cc (median 7.2 mmHg [range 5.5-9.6]), jelly 5 cc (median 6.0 mmHg [range 3.8-8.0]), and water 20 cc {(Median 4.8 mmHg [range 3.3-7.4]), P < 0.01}. DL were significantly different between water 5 cc, jelly 5 cc, and water 20 cc (P < 0.01), and in terms of PPT, proportions of small (2 cm ≤ < 5 cm) and large (5 cm≤) break for jelly 5 cc were significantly higher than those for the water 5 cc swallow (P < 0.05). Furthermore, DCI increased with age for water 5 cc, and a significant negative correlation was noticed between proportions of small break and BMI for water 5 cc. Manometric measurements vary depending on age, BMI, viscosity, and volume. These findings need to be taken into account in the interpretation of manometry results. © 2014 International Society for Diseases of the Esophagus.

The pebbles/boulders size distributions on Sais: Rosetta's final landing site on comet 67P/Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Pajola, M.; Lucchetti, A.; Fulle, M.; Mottola, S.; Hamm, M.; Da Deppo, V.; Penasa, L.; Kovacs, G.; Massironi, M.; Shi, X.; Tubiana, C.; Güttler, C.; Oklay, N.; Vincent, J. B.; Toth, I.; Davidsson, B.; Naletto, G.; Sierks, H.; Barbieri, C.; Lamy, P. L.; Rodrigo, R.; Koschny, D.; Rickman, H.; Keller, H. U.; Agarwal, J.; A'Hearn, M. F.; Barucci, M. A.; Bertaux, J. L.; Bertini, I.; Cremonese, G.; Debei, S.; De Cecco, M.; Deller, J.; El Maarry, M. R.; Fornasier, S.; Frattin, E.; Gicquel, A.; Groussin, O.; Gutierrez, P. J.; Höfner, S.; Hofmann, M.; Hviid, S. F.; Ip, W. H.; Jorda, L.; Knollenberg, J.; Kramm, J. R.; Kührt, E.; Küppers, M.; Lara, L. M.; Lazzarin, M.; Moreno, J. J. Lopez; Marzari, F.; Michalik, H.; Preusker, F.; Scholten, F.; Thomas, N.

2017-07-01

By using the imagery acquired by the Optical, Spectroscopic, and Infrared Remote Imaging System Wide-Angle Camera (OSIRIS WAC), we prepare a high-resolution morphological map of the Rosetta Sais final landing site, characterized by an outcropping consolidated terrain unit, a coarse boulder deposit and a fine particle deposit. Thanks to the 0.014 m resolution images, we derive the pebbles/boulders size-frequency distribution (SFD) of the area in the size range of 0.07-0.70 m. Sais' SFD is best fitted with a two-segment differential power law: the first segment is in the range 0.07-0.26 m, with an index of -1.7 ± 0.1, while the second is in the range 0.26-0.50 m, with an index of -4.2 +0.4/-0.8. The `knee' of the SFD, located at 0.26 m, is evident both in the coarse and fine deposits. When compared to the Agilkia Rosetta Lander Imaging System images, Sais surface is almost entirely free of the ubiquitous, cm-sized debris blanket observed by Philae. None the less, a similar SFD behaviour of Agilkia, with a steeper distribution above ˜0.3 m, and a flatter trend below that, is observed. The activity evolution of 67P along its orbit provides a coherent scenario of how these deposits were formed. Indeed, different lift pressure values occurring on the two locations and at different heliocentric distances explain the presence of the cm-sized debris blanket on Agilkia observed at 3.0 au inbound. Contrarily, Sais activity after 2.1 au outbound has almost completely eroded the fine deposits fallen during perihelion, resulting in an almost dust-free surface observed at 3.8 au.

Terahertz Frequency-Domain Spectroscopy of Low-Pressure Acetonitrile Gas by a Photomixing Terahertz Synthesizer Referenced to Dual Optical Frequency Combs

NASA Astrophysics Data System (ADS)

Hsieh, Yi-Da; Kimura, Hiroto; Hayashi, Kenta; Minamikawa, Takeo; Mizutani, Yasuhiro; Yamamoto, Hirotsugu; Iwata, Tetsuo; Inaba, Hajime; Minoshima, Kaoru; Hindle, Francis; Yasui, Takeshi

2016-09-01

A terahertz (THz) frequency synthesizer based on photomixing of two near-infrared lasers with a sub-THz to THz frequency offset is a powerful tool for spectroscopy of polar gas molecules due to its broad spectral coverage; however, its frequency accuracy and resolution are relatively low. To tune the output frequency continuously and widely while maintaining its traceability to a frequency standard, we developed a photomixing THz synthesizer phase-locked to dual optical frequency combs (OFCs). While the phase-locking to dual OFCs ensured continuous tuning within a spectral range of 120 GHz, in addition to the traceability to the frequency standard, use of a broadband uni-traveling carrier photodiode for photomixing enabled the generation of CW-THz radiation within a frequency range from 0.2 to 1.5 THz. We demonstrated THz frequency-domain spectroscopy of gas-phase acetonitrile CH3CN and its isotope CH3 13CN in the frequency range of 0.600-0.720 THz using this THz synthesizer. Their rotational transitions were assigned with a frequency accuracy of 8.42 × 10-8 and a frequency resolution of 520 kHz. Furthermore, the concentration of the CH3CN gas at 20 Pa was determined to be (5.41 ± 0.05) × 1014 molecules/cm3 by curve fitting analysis of the measured absorbance spectrum, and the mixture ratio of the mixed CH3CN/CH3 13CN gas was determined to be 1:2.26 with a gas concentration of 1014-1015 molecules/cm3. The developed THz synthesizer is highly promising for high-precision THz-FDS of low-pressure molecular gases and will enable the qualitative and quantitative analyses of multiple gases.

Simulated Performances of a Very High Energy Tomograph for Non-Destructive Characterization of large objects

NASA Astrophysics Data System (ADS)

Kistler, Marc; Estre, Nicolas; Merle, Elsa

2018-01-01

As part of its R&D activities on high-energy X-ray imaging for non-destructive characterization, the Nuclear Measurement Laboratory has started an upgrade of its imaging system currently implemented at the CEA-Cadarache center. The goals are to achieve a sub-millimeter spatial resolution and the ability to perform tomographies on very large objects (more than 100-cm standard concrete or 40-cm steel). This paper presentsresults on the detection part of the imaging system. The upgrade of the detection part needs a thorough study of the performance of two detectors: a series of CdTe semiconductor sensors and two arrays of segmented CdWO4 scintillators with different pixel sizes. This study consists in a Quantum Accounting Diagram (QAD) analysis coupled with Monte-Carlo simulations. The scintillator arrays are able to detect millimeter details through 140 cm of concrete, but are limited to 120 cm for smaller ones. CdTe sensors have lower but more stable performance, with a 0.5 mm resolution for 90 cm of concrete. The choice of the detector then depends on the preferred characteristic: the spatial resolution or the use on large volumes. The combination of the features of the source and the studies on the detectors gives the expected performance of the whole equipment, in terms of signal-over-noise ratio (SNR), spatial resolution and acquisition time.

Performance evaluation of D-SPECT: a novel SPECT system for nuclear cardiology

NASA Astrophysics Data System (ADS)

Erlandsson, Kjell; Kacperski, Krzysztof; van Gramberg, Dean; Hutton, Brian F.

2009-05-01

D-SPECT (Spectrum Dynamics, Israel) is a novel SPECT system for cardiac perfusion studies. Based on CZT detectors, region-centric scanning, high-sensitivity collimators and resolution recovery, it offers potential advantages over conventional systems. A series of measurements were made on a β-version D-SPECT system in order to evaluate its performance in terms of energy resolution, scatter fraction, sensitivity, count rate capability and resolution. Corresponding measurements were also done on a conventional SPECT system (CS) for comparison. The energy resolution of the D-SPECT system at 140 keV was 5.5% (CS: 9.25%), the scatter fraction 30% (CS: 34%), the planar sensitivity 398 s-1 MBq-1 per head (99mTc, 10 cm) (CS: 72 s-1 MBq-1), and the tomographic sensitivity in the heart region was in the range 647-1107 s-1 MBq-1 (CS: 141 s-1 MBq-1). The count rate increased linearly with increasing activity up to 1.44 M s-1. The intrinsic resolution was equal to the pixel size, 2.46 mm (CS: 3.8 mm). The average reconstructed resolution using the standard clinical filter was 12.5 mm (CS: 13.7 mm). The D-SPECT has superior sensitivity to that of a conventional system with similar spatial resolution. It also has excellent energy resolution and count rate characteristics, which should prove useful in dynamic and dual radionuclide studies.

Does resolution of flow field observation influence apparent habitat use and energy expenditure in juvenile coho salmon?

NASA Astrophysics Data System (ADS)

Tullos, D. D.; Walter, C.; Dunham, J.

2016-12-01

This study investigated how the resolution of observation influences interpretation of how fish, juvenile Coho Salmon (Oncorhynchus kisutch), exploit the hydraulic environment in streams. Our objectives were to evaluate how spatial resolution of the flow field observation influenced: 1) the velocities considered to be representative of habitat units; 2) patterns of use of the hydraulic environment by fish; and 3) estimates of energy expenditure. We addressed these objectives using observations within a 1:1 scale physical model of a full-channel log jam in an outdoor experimental stream. Velocities were measured with Acoustic Doppler Velocimetry at a 10 cm grid spacing, whereas fish locations and tailbeat frequencies were documented over time using underwater videogrammetry. Results highlighted that resolution of observation did impact perceived habitat use and energy expenditure, as did the location of measurement within habitat units and the use of averaging to summarize velocities within a habitat unit. In this experiment, the range of velocities and energy expenditure estimates increased with coarsening resolution, reducing the likelihood of measuring the velocities locally experienced by fish. In addition, the coarser resolutions contributed to fish appearing to select velocities that were higher than what was measured at finer resolutions. These findings indicate the need for careful attention to and communication of resolution of observation in investigating the hydraulic environment and in determining the habitat needs and bioenergetics of aquatic biota.

Tomographic Small-Animal Imaging Using a High-Resolution Semiconductor Camera

PubMed Central

Kastis, GA; Wu, MC; Balzer, SJ; Wilson, DW; Furenlid, LR; Stevenson, G; Barber, HB; Barrett, HH; Woolfenden, JM; Kelly, P; Appleby, M

2015-01-01

We have developed a high-resolution, compact semiconductor camera for nuclear medicine applications. The modular unit has been used to obtain tomographic images of phantoms and mice. The system consists of a 64 x 64 CdZnTe detector array and a parallel-hole tungsten collimator mounted inside a 17 cm x 5.3 cm x 3.7 cm tungsten-aluminum housing. The detector is a 2.5 cm x 2.5 cm x 0.15 cm slab of CdZnTe connected to a 64 x 64 multiplexer readout via indium-bump bonding. The collimator is 7 mm thick, with a 0.38 mm pitch that matches the detector pixel pitch. We obtained a series of projections by rotating the object in front of the camera. The axis of rotation was vertical and about 1.5 cm away from the collimator face. Mouse holders were made out of acrylic plastic tubing to facilitate rotation and the administration of gas anesthetic. Acquisition times were varied from 60 sec to 90 sec per image for a total of 60 projections at an equal spacing of 6 degrees between projections. We present tomographic images of a line phantom and mouse bone scan and assess the properties of the system. The reconstructed images demonstrate spatial resolution on the order of 1–2 mm. PMID:26568676

Shortwave quantum cascade laser frequency comb for multi-heterodyne spectroscopy

NASA Astrophysics Data System (ADS)

Lu, Q. Y.; Manna, S.; Wu, D. H.; Slivken, S.; Razeghi, M.

2018-04-01

Quantum cascade lasers (QCLs) are versatile light sources with tailorable emitting wavelengths covering the mid-infrared and terahertz spectral ranges. When the dispersion is minimized, frequency combs can be directly emitted from quantum cascade lasers via four-wave mixing. To date, most of the mid-infrared quantum cascade laser combs are operational in a narrow wavelength range wherein the QCL dispersion is minimal. In this work, we address the issue of very high dispersion for shortwave QCLs and demonstrate 1-W dispersion compensated shortwave QCL frequency combs at λ ˜ 5.0 μm, spanning a spectral range of 100 cm-1. The multi-heterodyne spectrum exhibits 95 equally spaced frequency comb lines, indicating that the shortwave QCL combs are ideal candidates for high-speed high-resolution spectroscopy.

Stand-alone polarization-modulation infrared reflection absorption spectroscopy instrument optimized for the study of catalytic processes at elevated pressures

NASA Astrophysics Data System (ADS)

Kestell, John D.; Mudiyanselage, Kumudu; Ye, Xinyi; Nam, Chang-Yong; Stacchiola, Dario; Sadowski, Jerzy; Boscoboinik, J. Anibal

2017-10-01

This paper describes the design and construction of a compact, "user-friendly" polarization-modulation infrared reflection absorption spectroscopy (PM-IRRAS) instrument at the Center for Functional Nanomaterials (CFN) of Brookhaven National Laboratory, which allows studying surfaces at pressures ranging from ultra-high vacuum to 100 Torr. Surface infrared spectroscopy is ideally suited for studying these processes as the vibrational frequencies of the IR chromophores are sensitive to the nature of the bonding environment on the surface. Relying on the surface selection rules, by modulating the polarization of incident light, it is possible to separate the contributions from the isotropic gas or solution phase, from the surface bound species. A spectral frequency range between 1000 cm-1 and 4000 cm-1 can be acquired. While typical spectra with a good signal to noise ratio can be obtained at elevated pressures of gases in ˜2 min at 4 cm-1 resolution, we have also acquired higher resolution spectra at 0.25 cm-1 with longer acquisition times. By way of verification, CO uptake on a heavily oxidized Ru(0001) sample was studied. As part of this test study, the presence of CO adsorbed on Ru bridge sites was confirmed, in agreement with previous ambient pressure X ray photoelectron spectroscopy studies. In terms of instrument performance, it was also determined that the gas phase contribution from CO could be completely removed even up to pressures close to 100 Torr. A second test study demonstrated the use of the technique for studying morphological properties of a spin coated polymer on a conductive surface. Note that this is a novel application of this technique. In this experiment, the polarization of incident light was modulated manually (vs. through a photoelastic modulator). It was demonstrated, in good agreement with the literature, that the polymer chains preferentially lie parallel with the surface. This PM-IRRAS system is small, modular, and easily reconfigurable. It also features a "vacuum suitcase" that allows for the integration of the PM-IRRAS system with the rest of the suite of instrumentation at our laboratory available to external users through the CFN user proposal system.

Observations of Seafloor Roughness in a Tidally Modulated Inlet

NASA Astrophysics Data System (ADS)

Lippmann, T. C.; Hunt, J.

2014-12-01

The vertical structure of shallow water flows are influenced by the presence of a bottom boundary layer, which spans the water column for long period waves or mean flows. The nature of the boundary is determined in part by the roughness elements that make up the seafloor, and includes sometimes complex undulations associated with regular and irregular shaped bedforms whose scales range several orders of magnitude from orbital wave ripples (10-1 m) to mega-ripples (100 m) and even larger features (101-103) such as sand waves, bars, and dunes. Modeling efforts often parameterize the effects of roughness elements on flow fields, depending on the complexity of the boundary layer formulations. The problem is exacerbated by the transient nature of bedforms and their large spatial extent and variability. This is particularly important in high flow areas with large sediment transport, such as tidally dominated sandy inlets like New River Inlet, NC. Quantification of small scale seafloor variability over large spatial areas requires the use of mobile platforms that can measure with fine scale (order cm) accuracy in wide swaths. The problem is difficult in shallow water where waves and currents are large, and water clarity is often limited. In this work, we present results from bathymetric surveys obtained with the Coastal Bathymetry Survey System, a personal watercraft equipped with a Imagenex multibeam acoustic echosounder and Applanix POS-MV 320 GPS-aided inertial measurement unit. This system is able to measure shallow water seafloor bathymetry and backscatter intensity with very fine scale (10-1 m) resolution and over relatively large scales (103 m) in the presence of high waves and currents. Wavenumber spectra show that the noise floor of the resolved multibeam bathymetry is on the order of 2.5 - 5 cm in amplitude, depending on water depths ranging 2 - 6 m, and about 30 cm in wavelength. Seafloor roughness elements are estimated from wavenumber spectra across the inlet from bathymetric maps of the seafloor obtained with 10-25 cm horizontal resolution. Implications of the effects of the bottom variability on the vertical structure of the currents will be discussed. This work was supported by ONR and NOAA.

High resolution X- and gamma-ray spectroscopy of solar flares

NASA Technical Reports Server (NTRS)

Lin, R. P.

1984-01-01

A balloon-borne X- and gamma-ray instrument was developed, fabricated, and flown. This instrument has the highest energy resolution of any instrument flown to date for measurements of solar and cosmic X-ray and gamma-ray emission in the 13 to 600 keV energy range. The purpose of the solar measurements was to study electron acceleration and solar flare energy release processes. The cosmic observations were to search for cyclotron line features from neutron stars and for low energy gamma-ray lines from nucleosynthesis. The instrument consists of four 4 cm diameter, 1.3 cm thick, planar intrinsic germanium detectors cooled by liquid nitrogen and surrounded by CsI and NaI anti-coincidence scintillation crystals. A graded z collimator limited the field of view to 3 deg x 6 deg and a gondola pointing system provided 0.3 deg pointing accuracy. A total of four flights were made with this instrument. Additional funding was obtained from NSF for the last three flights, which had primarily solar objectives. A detailed instrument description is given. The main scientific results and the data analysis are discussed. Current work and indications for future work are summarized. A bibliography of publications resulting from this work is given.

A l% and 1cm Perspective Leads to a Novel CDOM Absorption Algorithm

NASA Technical Reports Server (NTRS)

Morrow, J. H.; Hooker, S. B.; Matsuoka, A.

2012-01-01

A next-generation in-water profiler designed to measure the apparent optical properties of seawater was developed and validated across a wide dynamic range of water properties. This new Compact-Optical Profiling System (C-OPS) design uses a novel, kite-shaped, free-falling backplane with adjustable buoyancy and is based on 19 state-of-the-art microradiometers, spanning 320-780 nm. Data collected as part of the field commissioning were of a previously unachievable quality and showed that systematic uncertainties in the sampling protocols were discernible at the 1% optical and 1cm depth resolution levels. A sensitivity analysis as a function of three water types, established by the peak in the remote sensing reflectance spectra, revealed which water types and spectral domains were the most indicative of data acquisition uncertainties. The unprecedented vertical resolution of C-OPS measurements provided near-surface data products at the spectral endpoints with a quality level that has not been obtainable. The improved data allowed development of an algorithm for predicting the spectral absorption due to chromophoric dissolved organic matter (CDOM) using ratios of diffuse attenuation coefficients with over 99% of the variance in the data explained.

Comparative analysis of GOCI ocean color products.

PubMed

Amin, Ruhul; Lewis, Mark David; Lawson, Adam; Gould, Richard W; Martinolich, Paul; Li, Rong-Rong; Ladner, Sherwin; Gallegos, Sonia

2015-10-12

The Geostationary Ocean Color Imager (GOCI) is the first geostationary ocean color sensor in orbit that provides bio-optical properties from coastal and open waters around the Korean Peninsula at unprecedented temporal resolution. In this study, we compare the normalized water-leaving radiance (nLw) products generated by the Naval Research Laboratory Automated Processing System (APS) with those produced by the stand-alone software package, the GOCI Data Processing System (GDPS), developed by the Korean Ocean Research & Development Institute (KORDI). Both results are then compared to the nLw measured by the above water radiometer at the Ieodo site. This above-water radiometer is part of the Aerosol Robotic NETwork (AeroNET). The results indicate that the APS and GDPS processed  correlates well within the same image slot where the coefficient of determination (r²) is higher than 0.84 for all the bands from 412 nm to 745 nm. The agreement between APS and the AeroNET data is higher when compared to the GDPS results. The Root-Mean-Squared-Error (RMSE) between AeroNET and APS data ranges from 0.24 [mW/(cm²srμm)] at 555 nm to 0.52 [mW/(cm²srμm)]  at 412 nm while RMSE between AeroNET and GDPS data ranges from 0.47 [mW/(cm²srμm)] at 443 nm to 0.69 [mW/(cm²srμm)]  at 490 nm.

Comparative Analysis of GOCI Ocean Color Products

PubMed Central

Amin, Ruhul; Lewis, Mark David; Lawson, Adam; Gould, Richard W.; Martinolich, Paul; Li, Rong-Rong; Ladner, Sherwin; Gallegos, Sonia

2015-01-01

The Geostationary Ocean Color Imager (GOCI) is the first geostationary ocean color sensor in orbit that provides bio-optical properties from coastal and open waters around the Korean Peninsula at unprecedented temporal resolution. In this study, we compare the normalized water-leaving radiance (nLw) products generated by the Naval Research Laboratory Automated Processing System (APS) with those produced by the stand-alone software package, the GOCI Data Processing System (GDPS), developed by the Korean Ocean Research & Development Institute (KORDI). Both results are then compared to the nLw measured by the above water radiometer at the Ieodo site. This above-water radiometer is part of the Aerosol Robotic NETwork (AeroNET). The results indicate that the APS and GDPS processed nLw correlates well within the same image slot where the coefficient of determination (r2) is higher than 0.84 for all the bands from 412 nm to 745 nm. The agreement between APS and the AeroNET data is higher when compared to the GDPS results. The Root-Mean-Squared-Error (RMSE) between AeroNET and APS data ranges from 0.24 [mW/(cm2srμm)] at 555 nm to 0.52 [mW/(cm2srμm)] at 412 nm while RMSE between AeroNET and GDPS data ranges from 0.47 [mW/(cm2srμm)] at 443 nm to 0.69 [mW/(cm2srμm)] at 490 nm. PMID:26473861

Distributed temperature and strain discrimination with stimulated brillouin scattering and rayleigh backscatter in an optical fiber.

PubMed

Zhou, Da-Peng; Li, Wenhai; Chen, Liang; Bao, Xiaoyi

2013-01-31

A distributed optical fiber sensor with the capability of simultaneously measuring temperature and strain is proposed using a large effective area non-zero dispersion shifted fiber (LEAF) with sub-meter spatial resolution. The Brillouin frequency shift is measured using Brillouin optical time-domain analysis (BOTDA) with differential pulse-width pair technique, while the spectrum shift of the Rayleigh backscatter is measured using optical frequency-domain reflectometry (OFDR). These shifts are the functions of both temperature and strain, and can be used as two independent parameters for the discrimination of temperature and strain. A 92 m measurable range with the spatial resolution of 50 cm is demonstrated experimentally, and accuracies of ±1.2 °C in temperature and ±15 με in strain could be achieved.

Tailored pump compensation for Brillouin optical time-domain analysis with distributed Brillouin amplification.

PubMed

Kim, Young Hoon; Song, Kwang Yong

2017-06-26

A Brillouin optical time domain analysis (BOTDA) system utilizing tailored compensation for the propagation loss of the pump pulse is demonstrated for long-range and high-resolution distributed sensing. A continuous pump wave for distributed Brillouin amplification (DBA pump) of the pump pulse co-propagates with the probe wave, where gradual variation of the spectral width is additionally introduced to the DBA pump to obtain a uniform Brillouin gain along the position. In the experimental confirmation, a distributed strain measurement along a 51.2 km fiber under test is presented with a spatial resolution of 20 cm, in which the measurement error (σ) of less than 1.45 MHz and the near-constant Brillouin gain of the probe wave are maintained throughout the fiber.

The Feasibility of Tropospheric and Total Ozone Determination Using a Fabry-perot Interferometer as a Satellite-based Nadir-viewing Atmospheric Sensor. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Larar, Allen Maurice

1993-01-01

Monitoring of the global distribution of tropospheric ozone (O3) is desirable for enhanced scientific understanding as well as to potentially lessen the ill-health impacts associated with exposure to elevated concentrations in the lower atmosphere. Such a capability can be achieved using a satellite-based device making high spectral resolution measurements with high signal-to-noise ratios; this would enable observation in the pressure-broadened wings of strong O3 lines while minimizing the impact of undesirable signal contributions associated with, for example, the terrestrial surface, interfering species, and clouds. The Fabry-Perot Interferometer (FPI) provides high spectral resolution and high throughput capabilities that are essential for this measurement task. Through proper selection of channel spectral regions, the FPI optimized for tropospheric O3 measurements can simultaneously observe a stratospheric component and thus the total O3 column abundance. Decreasing stratospheric O3 concentrations may lead to an increase in biologically harmful solar ultraviolet radiation reaching the earth's surface, which is detrimental to health. In this research, a conceptual instrument design to achieve the desired measurement has been formulated. This involves a double-etalon fixed-gap series configuration FPI along with an ultra-narrow bandpass filter to achieve single-order operation with an overall spectral resolution of approximately .068 cm(exp -1). A spectral region of about 1 cm(exp -1) wide centered at 1054.73 cm(exp -1) within the strong 9.6 micron ozone infrared band is sampled with 24 spectral channels. Other design characteristics include operation from a nadir-viewing satellite configuration utilizing a 9 inch (diameter) telescope and achieving horizontal spatial resolution with a 50 km nadir footprint. A retrieval technique has been implemented and is demonstrated for a tropical atmosphere possessing enhanced tropospheric ozone amounts. An error analysis assessing the impact on retrieved O3 amounts of the most significant uncertainties associated with this particular measurement has been performed for several different types of atmospheres. Results show the proposed instrumentation to enable a good measurement of absolute ozone amounts and an even better determination of relative changes, with a range of accuracy to within 7.55 to 20.6 percent for integrated tropospheric amounts (and 1.99 to 4.02 percent for total O3 column abundance) and a corresponding range in precision to within 7.73 to 10.4 percent (and 3.30 to 3.95 percent for total O3 column abundance), for the atmospheric conditions considered.

Time averaging and stratigraphic disorder of molluscan assemblages in the Holocene sediments in the NE Adriatic (Piran)

NASA Astrophysics Data System (ADS)

Tomasovych, Adam; Gallmetzer, Ivo; Haselmair, Alexandra; Kaufman, Darrell S.; Zuschin, Martin

2016-04-01

Stratigraphic changes in temporal resolution of fossil assemblages and the degree of their stratigraphic mixing in the Holocene deposits are of high importance in paleoecology, conservation paleobiology and paleoclimatology. However, few studies quantified downcore changes in time averaging and in stratigraphic disorder on the basis of dating of multiple shells occurring in individual stratigraphic layers. Here, we investigate downcore changes in frequency distribution of postmortem ages of the infaunal bivalve Gouldia minima in two, ~150 cm-thick piston cores (separated by more than 1 km) in the northern Adriatic Sea, close to the Slovenian city Piran at a depth of 24 m. We use radiocarbon-calibrated amino acid racemization to obtain postmortem ages of 564 shells, and quantify age-frequency distributions in 4-5 cm-thick stratigraphic intervals (with 20-30 specimens sampled per interval). Inter-quartile range for individual 4-5 cm-thick layers varies between 850 and 1,700 years, and range encompassing 95% of age data varies between 2,000 and 5,000 years in both cores. The uppermost sediments (20 cm) are age-homogenized and show that median age of shells is ~700-800 years. The interval between 20 and 90 cm shows a gradual increase in median age from ~2,000 to ~5,000 years, with maximum age ranging to ~8,000 years. However, the lowermost parts of both cores show a significant disorder, with median age of 3,100-3,300 years. This temporal disorder implies that many shells were displaced vertically by ~1 m. Absolute and proportional abundance of the bivalve Gouldia minima strongly increases towards the top of the both cores. We hypothesize that such increase in abundance, when coupled with depth-declining reworking, can explain stratigraphic disorder because numerically abundant young shells from the top of the core were more likely buried to larger sediment depths than less frequent shells at intermediate sediment depths.

Fallout isotope chronology of the near-surface sediment record of Lake Bolătău.

PubMed

Bihari, Árpád; Karlik, Máté; Mîndrescu, Marcel; Szalai, Zoltán; Grădinaru, Ionela; Kern, Zoltán

2018-01-01

Fallout isotope ( 210 Pb ex, 137 Cs and 241 Am) based dating has been carried out on the near-surface sediment core collected from Lake Bolătău-Feredeu (Bukovina, Romania). The motivation was to improve the chronology of this recent section in connection with significant fluctuations observed in sediment accumulation rates, particle size distribution and primordial radioisotope (i.e. 40 K and 232 Th) composition. Previously only an extrapolation of a broad-range OxCal age-depth model, which was based on 8 AMS radiocarbon dates from the deeper part of a parallel sediment sequence and tentatively validated for the upper part using the double peaks of the 137 Cs activity concentration distribution, was available for the studied section (1-24 cm). Parallel to the previous 137 Cs measurement, 210 Pb and 226 Ra (for a more detailed, 210 Pb ex -based chronology), 241 Am (for an additional time-marker), as well as 40 K and 232 Th concentrations have also been determined by gamma-spectrometry. In case of the 210 Pb ex -based chronology, due to a large deviation from a pure exponential distribution, the Constant Flux (CF) model has been used for the calculation of sediment ages and accumulation rates. Although the broad-range OxCal and the CF model were broadly similar down to 22 cm, the 210 Pb ex -based ages are clearly superior in terms of uncertainty in the uppermost 12 cm, while the broad-range model has smaller uncertainty below 20 cm (>150 years). The CF model gave an average mass accumulation rate of (0.08 ± 0.03) g cm -2 yr -1 for sections 0-11 cm, and (0.03 ± 0.01) g cm -2 yr -1 for sections 12-22 cm, respectively. Significant changes have been observed in the depth distribution of both the particle size distribution and the elemental/isotopic composition of the sediment record, most likely related to the variation observable in the intensity and volume of precipitation in the catchment. The obtained high-resolution records of Lake Bolătău, including multiple radioisotopes, can serve as a regional benchmark for similar studies. Copyright © 2017 Elsevier Ltd. All rights reserved.

A new data set for estimating organic carbon storage to 3 m depth in soils of the northern circumpolar permafrost region

USGS Publications Warehouse

Hugelius, G.; Bockheim, James G.; Camill, P.; Elberling, B.; Grosse, G.; Harden, J.W.; Johnson, Kevin; Jorgenson, T.; Koven, C.D.; Kuhry, P.; Michaelson, G.; Mishra, U.; Palmtag, J.; Ping, C.-L.; O'Donnell, J.; Schirrmeister, L.; Schuur, E.A.G.; Sheng, Y.; Smith, L.C.; Strauss, J.; Yu, Z.

2013-01-01

High-latitude terrestrial ecosystems are key components in the global carbon cycle. The Northern Circumpolar Soil Carbon Database (NCSCD) was developed to quantify stocks of soil organic carbon (SOC) in the northern circumpolar permafrost region (a total area of 18.7 × 106 km2). The NCSCD is a geographical information system (GIS) data set that has been constructed using harmonized regional soil classification maps together with pedon data from the northern permafrost region. Previously, the NCSCD has been used to calculate SOC storage to the reference depths 0–30 cm and 0–100 cm (based on 1778 pedons). It has been shown that soils of the northern circumpolar permafrost region also contain significant quantities of SOC in the 100–300 cm depth range, but there has been no circumpolar compilation of pedon data to quantify this deeper SOC pool and there are no spatially distributed estimates of SOC storage below 100 cm depth in this region. Here we describe the synthesis of an updated pedon data set for SOC storage (kg C m-2) in deep soils of the northern circumpolar permafrost regions, with separate data sets for the 100–200 cm (524 pedons) and 200–300 cm (356 pedons) depth ranges. These pedons have been grouped into the North American and Eurasian sectors and the mean SOC storage for different soil taxa (subdivided into Gelisols including the sub-orders Histels, Turbels, Orthels, permafrost-free Histosols, and permafrost-free mineral soil orders) has been added to the updated NCSCDv2. The updated version of the data set is freely available online in different file formats and spatial resolutions that enable spatially explicit applications in GIS mapping and terrestrial ecosystem models. While this newly compiled data set adds to our knowledge of SOC in the 100–300 cm depth range, it also reveals that large uncertainties remain. Identified data gaps include spatial coverage of deep (> 100 cm) pedons in many regions as well as the spatial extent of areas with thin soils overlying bedrock and the quantity and distribution of massive ground ice. An open access data-portal for the pedon data set and the GIS-data sets is available online at http://bolin.su.se/data/ncscd/.

A new data set for estimating organic carbon storage to 3 m depth in soils of the northern circumpolar permafrost region

DOE PAGES

Hugelius, Gustaf; Bockheim, J. G.; Camill, P.; ...

2013-12-23

High-latitude terrestrial ecosystems are key components in the global carbon cycle. The Northern Circumpolar Soil Carbon Database (NCSCD) was developed to quantify stocks of soil organic carbon (SOC) in the northern circumpolar permafrost region (a total area of 18.7 × 10 6 km 2). The NCSCD is a geographical information system (GIS) data set that has been constructed using harmonized regional soil classification maps together with pedon data from the northern permafrost region. Previously, the NCSCD has been used to calculate SOC storage to the reference depths 0–30 cm and 0–100 cm (based on 1778 pedons). It has been shownmore » that soils of the northern circumpolar permafrost region also contain significant quantities of SOC in the 100–300 cm depth range, but there has been no circumpolar compilation of pedon data to quantify this deeper SOC pool and there are no spatially distributed estimates of SOC storage below 100 cm depth in this region. Here we describe the synthesis of an updated pedon data set for SOC storage (kg C m -2) in deep soils of the northern circumpolar permafrost regions, with separate data sets for the 100–200 cm (524 pedons) and 200–300 cm (356 pedons) depth ranges. These pedons have been grouped into the North American and Eurasian sectors and the mean SOC storage for different soil taxa (subdivided into Gelisols including the sub-orders Histels, Turbels, Orthels, permafrost-free Histosols, and permafrost-free mineral soil orders) has been added to the updated NCSCDv2. The updated version of the data set is freely available online in different file formats and spatial resolutions that enable spatially explicit applications in GIS mapping and terrestrial ecosystem models. While this newly compiled data set adds to our knowledge of SOC in the 100–300 cm depth range, it also reveals that large uncertainties remain. In conclusion, identified data gaps include spatial coverage of deep (> 100 cm) pedons in many regions as well as the spatial extent of areas with thin soils overlying bedrock and the quantity and distribution of massive ground ice.« less

Geochronology of Mudflow Deposits on the Mississippi River Delta Front, Louisiana, USA

NASA Astrophysics Data System (ADS)

Keller, G. P.; Bentley, S. J.; Xu, K.; Georgiou, I. Y.; Miner, M. D.; Obelcz, J.; Maloney, J. M.

2016-02-01

Short multicores (<50cm) and longer gravity cores (up to 3m) were collected seaward of the Southwest Pass of the Mississippi River Delta (Gulf of Mexico) and were analyzed to assess the frequency, extent, and potential causes of submarine mass wasting events. Cores were analyzed for radionuclide activity, grain size, and density at 2cm resolution, with x-radiography for the whole core. Short-term sedimentation rates calculated from 7Be are 2-12cm/y, while longer-term accumulation from 210Pb are only 1.3-5.5cm/y. In most cores, 210Pb activity steadily decreases downcore without displaying a "stairstep" nature. However, six cores have layers of low 210Pb activity stratigraphically above layers with higher activity. In one long core from a mudflow gully, 210Pb steadily decreases for the upper 90cm before stabilizing for the remaining 130cm. Clay content generally ranges between 25-40% and sand ranges between 5-15% with silt making up the rest of each sample. Sedimentation rates derived from 210Pb in the short cores indicate that proximity to the river mouth has stronger influence than depositional environment (mudflow gully, depositional lobe, prodelta). This finding may be explained by rapid sedimentation rates coupled with a reduced tropical cyclone activity over the delta in the last seven years (2006-2013). The regions of decreased 210Pb activity may be evidence of scavenging effects of plume sedimentation because they do not correspond with decreases in clay fraction. The zone of homogenized activity below 90cm in the gully core occurs at a depth equivalent to 18 years, indicating mixing on a decadal scale, potentially from mudflows. These results may be explained by a lack of recent mass failures corresponding with lulls in tropical cyclone activity over the delta, preceded by a period of more active hurricane-driven mudflow activity.

UAV photogrammetry for topographic monitoring of coastal areas

NASA Astrophysics Data System (ADS)

Gonçalves, J. A.; Henriques, R.

2015-06-01

Coastal areas suffer degradation due to the action of the sea and other natural and human-induced causes. Topographical changes in beaches and sand dunes need to be assessed, both after severe events and on a regular basis, to build models that can predict the evolution of these natural environments. This is an important application for airborne LIDAR, and conventional photogrammetry is also being used for regular monitoring programs of sensitive coastal areas. This paper analyses the use of unmanned aerial vehicles (UAV) to map and monitor sand dunes and beaches. A very light plane (SwingletCam) equipped with a very cheap, non-metric camera was used to acquire images with ground resolutions better than 5 cm. The Agisoft Photoscan software was used to orientate the images, extract point clouds, build a digital surface model and produce orthoimage mosaics. The processing, which includes automatic aerial triangulation with camera calibration and subsequent model generation, was mostly automated. To achieve the best positional accuracy for the whole process, signalised ground control points were surveyed with a differential GPS receiver. Two very sensitive test areas on the Portuguese northwest coast were analysed. Detailed DSMs were obtained with 10 cm grid spacing and vertical accuracy (RMS) ranging from 3.5 to 5.0 cm, which is very similar to the image ground resolution (3.2-4.5 cm). Where possible to assess, the planimetric accuracy of the orthoimage mosaics was found to be subpixel. Within the regular coastal monitoring programme being carried out in the region, UAVs can replace many of the conventional flights, with considerable gains in the cost of the data acquisition and without any loss in the quality of topographic and aerial imagery data.

An accurate global potential energy surface, dipole moment surface, and rovibrational frequencies for NH3

NASA Astrophysics Data System (ADS)

Huang, Xinchuan; Schwenke, David W.; Lee, Timothy J.

2008-12-01

A global potential energy surface (PES) that includes short and long range terms has been determined for the NH3 molecule. The singles and doubles coupled-cluster method that includes a perturbational estimate of connected triple excitations and the internally contracted averaged coupled-pair functional electronic structure methods have been used in conjunction with very large correlation-consistent basis sets, including diffuse functions. Extrapolation to the one-particle basis set limit was performed and core correlation and scalar relativistic contributions were included directly, while the diagonal Born-Oppenheimer correction was added. Our best purely ab initio PES, denoted "mixed," is constructed from two PESs which differ in whether the ic-ACPF higher-order correlation correction was added or not. Rovibrational transition energies computed from the mixed PES agree well with experiment and the best previous theoretical studies, but most importantly the quality does not deteriorate even up to 10300cm-1 above the zero-point energy (ZPE). The mixed PES was improved further by empirical refinement using the most reliable J =0-2 rovibrational transitions in the HITRAN 2004 database. Agreement between high-resolution experiment and rovibrational transition energies computed from our refined PES for J =0-6 is excellent. Indeed, the root mean square (rms) error for 13 HITRAN 2004 bands for J =0-2 is 0.023cm-1 and that for each band is always ⩽0.06cm-1. For J =3-5 the rms error is always ⩽0.15cm-1. This agreement means that transition energies computed with our refined PES should be useful in the assignment of new high-resolution NH3 spectra and in correcting mistakes in previous assignments. Ideas for further improvements to our refined PES and for extension to other isotopolog are discussed.

Design and fabrication of prototype 6×6 cm 2 microchannel plate photodetector with bialkali photocathode for fast timing applications

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

Xie, Junqi; Byrum, Karen; Demarteau, Marcel

Planar microchannel plate-based photodetector with bialkali photocathode is capable of fast and accurate time and position resolutions. A new 6 cm x 6 cm photodetector production facility was designed and built at Argonne National Laboratory. Small form-factor MCP-based photodetectors completely constructed of glass were designed and prototypes were successfully fabricated. Knudsen effusion cells were incorporated in the photocathode growth chamber to achieve uniform and high quantum efficiency hotocathodes. The thin film uniformity distribution was simulated and measured for an antimony film deposition, showing uniformity of better than 10%. Several prototype devices with bialkali photocathodes have been fabricated with the describedmore » system and their characteristics were evaluated in the large signal (multi-PE) limit. A typical prototype device exhibits time-of-flight resolution of ~ 27 psec and differential time resolution of ~ 9 psec, corresponding to spatial resolution of ~ 0.65 mm.« less

Propane spectral resolution enhancement by the maximum entropy method

NASA Technical Reports Server (NTRS)

Bonavito, N. L.; Stewart, K. P.; Hurley, E. J.; Yeh, K. C.; Inguva, R.

1990-01-01

The Burg algorithm for maximum entropy power spectral density estimation is applied to a time series of data obtained from a Michelson interferometer and compared with a standard FFT estimate for resolution capability. The propane transmittance spectrum was estimated by use of the FFT with a 2 to the 18th data sample interferogram, giving a maximum unapodized resolution of 0.06/cm. This estimate was then interpolated by zero filling an additional 2 to the 18th points, and the final resolution was taken to be 0.06/cm. Comparison of the maximum entropy method (MEM) estimate with the FFT was made over a 45/cm region of the spectrum for several increasing record lengths of interferogram data beginning at 2 to the 10th. It is found that over this region the MEM estimate with 2 to the 16th data samples is in close agreement with the FFT estimate using 2 to the 18th samples.

Emission spectra of a pulse needle-to-plane corona-like discharge in conductive aqueous solutions

NASA Astrophysics Data System (ADS)

Šimek, Milan; Člupek, Martin; Babický, Václav; Lukeš, Petr; Šunka, Pavel

2012-10-01

We explored basic optical and electrical characteristics of a positive corona-like discharge produced in conductive aqueous solutions by periodic high-voltage pulses. Emission spectra of the discharge were acquired in a needle-to-plate electrode geometry and analysed in the UV-vis-NIR spectral range with nanosecond time resolution for the solution conductivity of 100 and 500 µS cm-1. The most important emission features are due to electronic excitation of HI, OI, OII and OH species. We found evidence of significant time-dependent line-shape broadening of selected HI and OI transitions. The observed broadening is attributed to the dynamic Stark and pressure broadening mechanisms and significantly increases with the aqueous solution conductivity. Electron densities were estimated by fitting a single Voigt peak function to the observed Hα profiles, and can reach as much as ne ≅ 4 × 1018 cm-3 (tD = 300 ns at 100 µS cm-1 solution conductivity) and ne ≅ 5 × 1018 cm-3 (tD = 1 µs at 500 µS cm-1). Temporal evolution of the partially resolved rotational structure of the OH emission reaches a maximum during the discharge decay, with the onset significantly delayed with respect to the streamer ignition.

Resonant two-photon ionization spectroscopy of jet-cooled OsSi

NASA Astrophysics Data System (ADS)

Johnson, Eric L.; Morse, Michael D.

2015-09-01

The optical spectrum of diatomic OsSi has been investigated for the first time, with transitions observed in the range from 15 212 to 18 634 cm-1 (657-536 nm). Two electronic band systems have been identified along with a number of unclassified bands. Nine bands have been investigated at rotational resolution, allowing the ground state to be identified as X 3 Σ0 + - , arising from the 1σ21π42σ23σ21δ2 configuration. The ground X 3 Σ0 + - state is characterized by re = 2.1207(27) Å and ΔG1/2″ = 516.315(4) cm-1 for the most abundant isotopologue, 192Os28Si (38.63%). The A1 excited electronic state, which is thought to be primarily 3Π1 in character, is characterized by T0 = 15 727.7(7) cm-1, ωe = 397.0(7) cm-1, and re = 2.236(16) Å for 192Os28Si. The B1 excited electronic state is characterized by T0 = 18 468.71 cm-1, ΔG1/2 = 324.1 cm-1, and re = 2.1987(20) Å for 192Os28Si and is thought to be primarily 1Π1 in character. These results are placed in context through a comparison to other transition metal carbides and silicides.

2-D inner-shelf current observations from a single VHF WEllen RAdar (WERA) station

USGS Publications Warehouse

Voulgaris, G.; Kumar, N.; Gurgel, K.-W.; Warner, J.C.; List, J.H.

2011-01-01

The majority of High Frequency (HF) radars used worldwide operate at medium to high frequencies (8 to 30 MHz) providing spatial resolutions ranging from 3 to 1.5 km and ranges from 150 to 50 km. This paper presents results from the deployment of a single Very High Frequency (VHF, 48 MHz) WEllen RAdar (WERA) radar with spatial resolution of 150 m and range 10-15 km, used in the nearshore off Cape Hatteras, NC, USA. It consisted of a linear array of 12 antennas operating in beam forming mode. Radial velocities were estimated from radar backscatter for a variety of wind and nearshore wave conditions. A methodology similar to that used for converting acoustically derived beam velocities to an orthogonal system is presented for obtaining 2-D current fields from a single station. The accuracy of the VHF radar-derived radial velocities is examined using a new statistical technique that evaluates the system over the range of measured velocities. The VHF radar velocities showed a bias of 3 to 7 cm/s over the experimental period explainable by the differences in radar penetration and in-situ measurement height. The 2-D current field shows good agreement with the in-situ measurements. Deviations and inaccuracies are well explained by the geometric dilution analysis. ?? 2011 IEEE.

Identification of the HNO3 3 nu(sub 9) - nu(sub 9) band Q branch in stratospheric solar occultation spectra

NASA Technical Reports Server (NTRS)

Perrin, A.; Flaud, J.-M.; Camy-Peyret, C.; Goldman, A.; Rinsland, C. P.; Gunson, M. R.

1994-01-01

The spectroscopic identification for the HNO3 3 nu(sub 9) - nu(sub 9) band Q branch at 830.4/cm is reported based on 0.01/cm resolution solar occultation spectra of the lower stratosphere recorded by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer and a recent analysis of this band. Least-squares fits to 0.0025/cm resolution laboratory spectra in the Q branch region indicate an integrated intensity of 0.529 x 10(exp -18)/cm/mol/sq cm at 296 K for this weak band. Stratospheric HNO3 retrievals derived from the ATMOS data are consistent with this value within its estimated uncertainty of about +/- 30%. A set of spectroscopic line parameters suitable for atmospheric studies has been generated.

Potentials of acousto-optical spectrum analysis on a basis of a novel algorithm of the collinear wave heterodyning in a large-aperture KRS-5 crystalline cell

NASA Astrophysics Data System (ADS)

Shcherbakov, Alexandre S.; Maximov, Jewgenij; Bliznetsov, Alexej M.; Sanchez Perez, Karla J.

2011-03-01

The technique under proposal for a precise spectrum analysis within an algorithm of the collinear wave heterodyning implies a two-stage integrated processing, namely, the wave heterodyning of a signal in a square-law nonlinear medium and then the optical processing in the same solid state cell. The technical advantage of this approach lies in providing a direct multichannel parallel processing of ultra-high-frequency radio-wave signals with essentially improved frequency resolution. This technique imposes specific requirements on the cell's material. We focus our attention on the solid solutions of thallium chalcogenides and take the TlBr-TlI (thallium bromine-thallium iodine) solution, which forms KRS-5 cubic-symmetry crystals with the mass-ratio 58% of TlBr to 42% of TlI. Analysis shows that the acousto-optical cell made of a KRS-5 crystal oriented along the [111]-axis and the corresponding longitudinal elastic mode for producing the dynamic diffractive grating can be exploited. With the acoustic velocity of about 1.92 × 105 cm/s and attenuation of ~10 dB/(cm GHz2), a similar cell is capable of providing an optical aperture of ~5.0 cm and one of the highest figures of acousto-optical merit in solid states in the visible range. Such a cell is rather desirable for the application to direct 5000-channel parallel spectrum analysis with an improved up to 10-5 relative frequency resolution.

Inflight proton activation and damage on a CdTe detection plane

NASA Astrophysics Data System (ADS)

Simões, N.; Maia, J. M.; Curado da Silva, R. M.; Ghithan, S.; Crespo, P.; do Carmo, S. J. C.; Alves, Francisco; Moita, M.; Auricchio, N.; Caroli, E.

2018-01-01

Future high-energy space telescope missions require further analysis of orbital environment induced activation and radiation damage on main instruments. A scientific satellite is exposed to the charged particles harsh environment, mainly geomagnetically trapped protons (up to ∼300 MeV) that interact with the payload materials, generating nuclear activation background noise within instruments' operational energy range and causing radiation damage in detector material. As a consequence, instruments' performances deteriorate during the mission time-frame. In order to optimize inflight operational performances of future CdTe high-energy telescope detection planes under orbital radiation environment, we measured and analyzed the effects generated by protons on CdTe ACRORAD detectors with 2.56 cm2 sensitive area and 2 mm thickness. To carry-out this study, several sets of measurements were performed under a ∼14 MeV cyclotron proton beam. Nuclear activation radionuclides' identification was performed. Estimation of activation background generated by short-lived radioisotopes during one day was less than ∼1.3 ×10-5 counts cm-2 s-1 keV-1 up to 800 keV. A noticeable gamma-rays energy resolution degradation was registered (∼60% @ 122 keV, ∼14% @ 511 and ∼2.2% @ 1275 keV) after an accumulated proton fluence of 4.5 ×1010 protons cm-2, equivalent to ∼22 years in-orbit fluence. One year later, the energy resolution of the irradiated prototype showed a good level of performancerecovery.

Development of EXITE2: a large-area imaging phoswich detector/telescope for hard x-ray astronomy

NASA Astrophysics Data System (ADS)

Manandhar, Raj P.; Lum, Kenneth S.; Eikenberry, Stephen S.; Krockenberger, Martin; Grindlay, Jonathan E.

1993-11-01

We review design considerations and present preliminary details of the performance of a new imaging system for hard X-ray astronomy in the 20 - 600 keV energy range. The detector is a 40 cm X 40 cm NaI(Tl)/CsI(Na) phoswich module, read out by a 7 X 7 array of square PMTs. The detector comprises the main part of the next generation Energetic X-ray Imaging Telescope Experiment (EXITE2), which had its first flight on 13 June 1993 from Palestine, Texas. Imaging is accomplished via the coded-aperture mask technique. The mask consists of 16 mm square lead/tin/copper pixels arranged in a cyclically repeated 13 X 11 uniformly redundant array pattern at a focal length of 2.5 m, giving 22 arcmin resolution. The field of view, determined by the lead/brass collimator (16 mm pitch) is 4.65 degrees FWHM. We anticipate a 3 sigma sensitivity of 1 X 10(superscript -5) photons cm(superscript -2) s(superscript -1) keV(superscript -1) at 100 keV in a 10(superscript 4) sec balloon observation. The electronics incorporate two on-board computers, providing a future capability to record the full data stream and telemeter compressed data. The design of the current detector and electronics allows an upgrade to EXITE3, which adds a proportional counter front-end to achieve lower background and better spatial and spectral resolution below approximately 100 keV.

Monitoring of spatiotemporal patterns of Net and Gross Primary Productivity (NPP & GPP) and their ratios (NPP/GPP) derived from MODIS data: assessment natural drivers and their effects on NDVI anomalies in arid and semi-arid zones of Central Asia.

NASA Astrophysics Data System (ADS)

Aralova, Dildora; Jarihani, Ben; Khujanazarov, Timur; Toderich, Kristina; Gafurov, Dilshod; Gismatulina, Liliya

2017-04-01

Previous studies have shown that precipitation anomalies and raising of temperature trends were deteriorate affected on large-scale of vegetation surveys in Central Asia (CA). Nowadays, remote sensing techniques can provide estimation of Net and Gross Primary Productivity (NPP & GPP) for regional and global scales, and selected zones in CA (Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan) dominated by C4 plants (biomes) what it reveals more accurately simulate C4 carbon. The estimation of NPP & GPP from source (MOD17A2/A3) would be beneficial to determine natural driver factors, whether on rangeland ecosystem is a carbon sink or source, such as a vast area of the selected zones incorporates exacerbate regional drought-risk factors nowadays. Generally, we have combined last available NPP & GPP (2000-2015) with 1 km resolution from MODIS, with investigation of long-term vegetation patterns under Normalized Difference Vegetation Indices (NDVI) with 8 km resolution from AVHRR-GIMMS 3g sources (2001-2015) within aim to estimate potential values of rangeland ecosystems. Interaction ratios of NPP/GPP are integrating more accurately describe carbon sink process under natural or anthropogenic factors, specifically last results of NDVI trends were described as decreasing trends due to climate anomalies, besides the eastern and northern parts of CA (mostly boreal forest zones) where accumulated or indicated of raising trends of NDVI in last three years (2012-2015). Results revealed that, in CA were averaged annually value NDVI ranges from 0.19-0.21; (Kyrgyzstan: 0.23-0.26; Kazakhstan: 0.21-0.24; Tajikistan: 0.19-0.21); and resting countries as low NDVI accumulated areas were Turkmenistan and Uzbekistan ranges 0.13-0.16; Comparing datasets of GPP given the response dynamic change structures of NDVI values and explicit carbon uptake (CO2) in arid ecosystems and average GPPyearlyin CA ranges 2.42 kg C/m2; including to Tajikistan, Uzbekistan (3.09 kg C/m2) and Turkmenistan (3.59 kg C/m2); Kazakhstan and Kyrgyzstan 0.88 & 1.46 kg C /m2. The ratings of dynamical GPP & NPP were similar for each 5 years (2000-2005, 2005-2010 and 2010-2015) and ranges GPP ≈ 2.42 kg C/m2 and NPP ≈ 2.36 kg C/m2. NPP is more accuracy in desert zones, basically, the bare areas shown a high values. The results shown that meanwhile values of NPP/GPP is relatively illustrated same results as NDVI annual trends, and NPP/GPP average value of 1.03, and incorporating well for sparsely vegetated ecosystems of CA. MODIS derived primary production datasets could improve a better estimate ecosystem process and vegetation/carbon change anomalies during water-stressed conditions in the regional level.

Development of a 3D Brain PET Scanner Using CdTe Semiconductor Detectors and Its First Clinical Application

NASA Astrophysics Data System (ADS)

Morimoto, Y.; Ueno, Y.; Takeuchi, W.; Kojima, S.; Matsuzaki, K.; Ishitsu, T.; Umegaki, K.; Kiyanagi, Y.; Kubo, N.; Katoh, C.; Shiga, T.; Shirato, H.; Tamaki, N.

2011-10-01

Targeting improved spatial resolution, a three-dimensional positron-emission-tomography (PET) scanner employing CdTe semiconductor detectors and using depth-of-interaction (DOI) information was developed, and its physical performance was evaluated. This PET scanner is the first to use semiconductor detectors dedicated to the human brain and head-and-neck region. Imaging performance of the scanner used for 18F -fluorodeoxy glucose (FDG) scans of phantoms and human brains was evaluated. The gantry of the scanner has a 35.0-cm-diameter patient port, the trans-axial field of view (FOV) is 31.0 cm, and the axial FOV is 24.6 cm. The energy resolution averaged over all detector channels and timing resolution were 4.1% and 6.8 ns (each in FWHM), respectively. Spatial resolution measured at the center of FOV was 2.3-mm FWHM-which is one of the best resolutions achieved by human PET scanners. Noise-equivalent count ratio (NEC2R) has a maximum in the energy window of 390 to 540 keV and is 36 kcps/Bq/cm3 at 3.7 kBq/cm3 . The sensitivity of the system according to NEMA 1994 was 25.9 cps/Bq/cm3. Scatter fraction of the scanner is 37% for the energy window of 390 to 540 keV and 23% for 450 to 540 keV. Images of a hot-rod phantom and images of brain glucose metabolism show that the structural accuracy of the images obtained with the semiconductor PET scanner is higher than that possible with a conventional Bismuth Germanium Oxide (BGO) PET scanner. In addition, the developed scanner permits better delineation of the head-and-neck cancer. These results show that the semiconductor PET scanner will play a major role in the upcoming era of personalized medicine.

WE-EF-303-08: Proton Radiography Using Pencil Beam Scanning and Novel Micromegas Detectors

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

Dolney, D; Lustig, R; Teo, B

Purpose: While the energy of therapeutic proton beams can be adjusted to penetrate to any given depth in water, range uncertainties arise in patients due in part to imprecise knowledge of the stopping power of protons in human tissues. Proton radiography is one approach to reduce the beam range uncertainty, thereby allowing for a reduction in treatment margins and dose escalation. Methods: The authors have adapted a novel detector technology based on Micromesh Gaseous Structure (“Micromegas”) for proton therapy beams and have demonstrated fine spatial and time resolution of magnetically scanned proton pencil beams, as well as wide dynamic rangemore » for dosimetry. In this work, proton radiographs were obtained using Micromegas 2D planes positioned downstream of solid water assemblies. The position-sensitive monitor chambers in the IBA proton delivery nozzle provide the beam entrance position. Results: Radiography with Micromegas detectors and actively scanned beams provide spatial resolution of up to 300 µm and water-equivalent thickness (WET) resolution as good as 0.02% (60 µm out of 31 cm total thickness), with the dose delivered to the patient kept below 2 cGy. The spatial resolution as a function of sample rate and number of delivered protons is found to be near the theoretical Cramer-Rao lower bound. Using the CR bound, we argue that the imaging dose could be further lowered to 1 mGy, while still achieving sub-mm spatial resolution, by relatively simple instrumentation upgrades and beam delivery modifications. Conclusion: For proton radiography, high spatial and WET resolution can be achieved, with minimal additional dose to patient, by using magnetically scanned proton pencil beams and Micromegas detectors.« less

Feasibility study and quality assessment of unmanned aircraft system-derived multispectral images

NASA Astrophysics Data System (ADS)

Chang, Kuo-Jen

2017-04-01

The purpose of study is to explore the precision and the applicability of UAS-derived multispectral images. In this study, the Micro-MCA6 multispectral camera was mounted on quadcopter. The Micro-MCA6 shoot images synchronized of each single band. By means of geotagged images and control points, the orthomosaic images of each single band generated firstly by 14cm resolution. The multispectral image was merged complete with 6 bands. In order to improve the spatial resolution, the 6 band image fused with 9cm resolution image taken from RGB camera. Quality evaluation of the image is verified of the each single band by using control points and check points. The standard deviations of errors are within 1 to 2 pixel resolution of each band. The quality of the multispectral image is compared with 3 cm resolution orthomosaic RGB image gathered from UAV in the same mission, as well. The standard deviations of errors are within 2 to 3 pixel resolution. The result shows that the errors resulting from the blurry and the band dislocation of the objects edge identification. To the end, the normalized difference vegetation index (NDVI) extracted from the image to explore the condition of vegetation and the nature of the environment. This study demonstrates the feasibility and the capability of the high resolution multispectral images.

Heat capacity and thermal relaxation of bulk helium very near the lambda point

NASA Technical Reports Server (NTRS)

Lipa, John A.; Swanson, D. R.; Nissen, J. A.; Chui, T. C. P.

1994-01-01

In October 1992 a low temperature experiment was flown on the Space Shuttle in low Earth orbit. The objective of the mission was to measure the heat capacity and thermal conductivity of helium very close to the lambda point with the smearing effect of gravity removed. We report preliminary results from the experiment, and compare them with related measurements performed on the ground. The sample was s sphere of helium 3.5 cm in diameter contained within a copper calorimeter of vey high thermal conductivity. The calorimeter was attached to a pair of high resolution paramagnetic salt thermometers with noise levels in the 10(exp -10) K range and suspended from a high stability thermal isolation system. During the mission we found that the resolution of the thermometers was degraded somewhat due to the impact of charged particles. This effect limited the useful resolution of the measurements to about two nanokelvins from the lambda point. The results reported here are limited to about ten nanokelvins from the transition.

Standoff imaging of a masked human face using a 670 GHz high resolution radar

NASA Astrophysics Data System (ADS)

Kjellgren, Jan; Svedin, Jan; Cooper, Ken B.

2011-11-01

This paper presents an exploratory attempt to use high-resolution radar measurements for face identification in forensic applications. An imaging radar system developed by JPL was used to measure a human face at 670 GHz. Frontal views of the face were measured both with and without a ski mask at a range of 25 m. The realized spatial resolution was roughly 1 cm in all three dimensions. The surfaces of the ski mask and the face were detected by using the two dominating reflections from amplitude data. Various methods for visualization of these surfaces are presented. The possibility to use radar data to determine certain face distance measures between well-defined face landmarks, typically used for anthropometric statistics, was explored. The measures used here were face length, frontal breadth and interpupillary distance. In many cases the radar system seems to provide sufficient information to exclude an innocent subject from suspicion. For an accurate identification it is believed that a system must provide significantly more information.

Lattice contraction with boron doping in fully strained SiGe epitaxial layers

NASA Astrophysics Data System (ADS)

Shin, Keun Wook; Song, Sukchan; Kim, Hyun-Woo; Lee, Gun-Do; Yoon, Euijoon

2018-06-01

Changes in lattice constants of epitaxial SiGe layers by boron (B) doping were studied by using high resolution X-ray diffraction (HRXRD) by using SiGe:B with Ge and B concentrations in the range of 11–23% and (1.5–4.2) × 1019 cm‑3, respectively. The lattice contraction coefficient (β) of B in SiGe was measured to be (9.6 ± 0.6) × 10‑24 cm3, which was approximately twice as large as that of B in Si. The ab initio calculation of β, 9.35 × 10‑24 cm3, was in excellent agreement with the experiment. From the ab initio calculation, it is found that the large lattice contraction is due to the favorability of Si–B bond than Si–Ge bond.

Air-Broadening of H2O as a Function of Temperature: 696 - 2163 cm(exp -1)

NASA Technical Reports Server (NTRS)

Toth, R. A.; Brown, L. R.; Smith, M. A. H.; Devi, V. Malathy; Benner, D. Chris; Dulick, M.

2006-01-01

The temperature dependence of air-broadened halfwidths are reported for some 500 transitions in the (000)-(000) and (010)-(000) bands of H2(16)O using gas sample temperatures ranging from 241 to 388 K. These observations were obtained from infrared laboratory spectra recorded at 0.006 to 0.011 cm(exp-1) resolution with the McMath-Pierce Fourier transform spectrometer located at Kitt Peak. The experimental values of the temperature dependence exponents, eta, were grouped into eight subsets and fitted to empirical functions in a semi-global procedure. Overall, the values of eta were found to decrease with increasing rotational quantum number J. The number of measurements (over 2200) and transitions (586) involved exceeds by a large margin that of any other comparable reported study.

Large area silicon drift detectors for x-rays -- New results

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

Iwanczyk, J.S.; Patt, B.E.; Tull, C.R.

Large area silicon drift detectors, consisting of 8 mm and 12 mm diameter hexagons, were fabricated on 0.35 mm thick high resistivity n-type silicon. An external FET and a low-noise charge sensitive preamplifier were used for testing the prototype detectors. The detector performance was measured in the range {minus}75 to 25 C using Peltier cooling, and from 0.125 to 6 {micro}s amplifier shaping time. Measured energy resolutions were 159 eV FWHM and 263 eV FWHM for the 0.5 cm{sup 2} and 1 cm{sup 2} detectors, respectively (at 5.9 keV, {minus}75 C, 6 {micro}s shaping time). The uniformity of the detectormore » response over the entire active area (measured using 560 nm light) was <0.5%.« less

Preliminary infrared radiometry of the night side of mercury from mariner 10.

PubMed

Chase, S C; Miner, E D; Morrison, D; Münch, G; Neugebauer, G; Schroeder, M

1974-07-12

The infrared radiometer on Mariner 10 measured the thermal emission from the planet with a spatial resolution element as small as 40 kilometers in a broad wavelength band centered at 45 micrometers. The minimum brightness temperature (near local midnight) in these near-equatorial scans was 100 degrees K. Along the track observed, the temperature declined steadily from local sunset to near midnight, behaving as would be expected for a homogeneous, porous material with a thermal inertia of 0.0017 cal cm(-2) sec(-(1/2)) degrees K(-1), a value only slightly larger than that of the moon. From near midnight to dawn, however, the temperature fluctuated over a range of about 10 degrees K, implying the presence of regions having thermal inertia as high as 0.003 cal cm(-2) sec-(1/2) degrees K(-1).

Camera-based micro interferometer for distance sensing

NASA Astrophysics Data System (ADS)

Will, Matthias; Schädel, Martin; Ortlepp, Thomas

2017-12-01

Interference of light provides a high precision, non-contact and fast method for measurement method for distances. Therefore this technology dominates in high precision systems. However, in the field of compact sensors capacitive, resistive or inductive methods dominates. The reason is, that the interferometric system has to be precise adjusted and needs a high mechanical stability. As a result, we have usual high-priced complex systems not suitable in the field of compact sensors. To overcome these we developed a new concept for a very small interferometric sensing setup. We combine a miniaturized laser unit, a low cost pixel detector and machine vision routines to realize a demonstrator for a Michelson type micro interferometer. We demonstrate a low cost sensor smaller 1cm3 including all electronics and demonstrate distance sensing up to 30 cm and resolution in nm range.

Observability of atomic line features in strong magnetic fields

NASA Technical Reports Server (NTRS)

Wunner, G.; Ruder, H.; Herold, H.; Truemper, J.

1981-01-01

The physical properties of atoms in superstrong magnetic fields, characteristic of neutron stars, and the possibility of detecting magnetically strongly shifted atomic lines in the spectra of magnetized X-ray pulsars are discussed. It is suggested that it is recommendable to look for magnetically strongly shifted Fe 26 Lyman lines in rotating neutron stars of not too high luminosity using spectrometers working in the energy range 10 - 20 keV, with sensitivities to minus 4 power photons per sq cm and second, and resolution E/delta E approx. 10-100.

Detection of atomic oxygen and further line assignments in the far-infrared stratospheric spectrum

NASA Technical Reports Server (NTRS)

Carli, B.; Mencaraglia, F.; Bonetti, A.; Carlotti, M.; Nolt, I.

1985-01-01

Recent progress in high-resolution measurement of sub-millimeter and far-infrared emission in the stratosphere is reviewed. Attention is given to the results of recent balloon measurements of the minor stratospheric constituents in the spectral range 40-190 per cm. Emission spectra are presented for HCl; HF; and OH. Emission spectra were also obtained for atomic oxygen; hydrobromic acid; and hydroperoxyl radical. The possibility of detecting HO2 and H2O2 in the far-infrared is also briefly discussed.

Observation of several chlorine nitrate (ClONO2) bands in stratospheric infrared spectra

NASA Technical Reports Server (NTRS)

Zander, R.; Rinsland, C. P.; Farmer, C. B.; Brown, L. R.; Norton, R. H.

1986-01-01

Four of the most prominent and sharpest infrared absorption features of chlorine nitrate at 780.2, 807.7, 809.4, and 1292.6/cm have been observed in a series of infrared solar spectra obtained at an unapodized spectral resolution of 0.01/cm, using the Atmospheric Trace Molecule Spectroscopy instrument from on-board Sapcelab 3. A quantitative analysis of the nu4 Q branch at 780.2/cm has provided insight into the concentration of ClONO2 between 19 and 40 km altitude. While the mean profile deduced from three sunset occultations near 30 deg N latitude exhibits a shape close to that predicted by model calculations, its concentrations in the 20 to 32 km altitude range are, however, about 30 percent larger, reaching a peak concentration of 9 x 10 to the 8th molecules/cu cm at 25 km. The concentrations above 32 km, deduced from one sunrise occultation at 47 deg JS, are even larger than the corresponding sunset values at 30 deg N latitude. Some of these discrepancies may be caused by the rather large uncertainty in the assumed Q branch strength.

Structural analysis of ion-implanted chemical-vapor-deposited diamond by transmission electron microscope

NASA Astrophysics Data System (ADS)

Jiang, N.; Deguchi, M.; Wang, C. L.; Won, J. H.; Jeon, H. M.; Mori, Y.; Hatta, A.; Kitabatake, M.; Ito, T.; Hirao, T.; Sasaki, T.; Hiraki, A.

1997-04-01

A transmission electron microscope (TEM) study of ion-implanted chemical-vapor-deposited (CVD) diamond is presented. CVD diamond used for transmission electron microscope observation was directly deposited onto Mo TEM grids. As-deposited specimens were irradiated by C (100 keV) ions at room temperature with a wide range of implantation doses (10 12-10 17/cm 2). Transmission electron diffraction (TED) patterns indicate that there exists a critical dose ( Dc) for the onset of amorphization of CVD diamond as a result of ion induced damage and the value of critical dose is confirmed to be about 3 × 10 15/cm 2. The ion-induced transformation process is clearly revealed by high resolution electron microscope (HREM) images. For a higher dose implantation (7 × 10 15/cm 2) a large amount of diamond phase is transformed into amorphous carbon and many tiny misoriented diamond blocks are found to be left in the amorphous solid. The average size of these misoriented diamond blocks is only about 1-2 nm. Further bombardment (10 17/cm 2) almost kills all of the diamond phase within the irradiated volume and moreover leads to local formation of micropolycrystalline graphite.

NGC 1058: Gas motions in an extended, quiescent spiral disk

NASA Technical Reports Server (NTRS)

Hanson, Margaret Murray; Dickey, John M.; Helou, George

1990-01-01

Researchers investigate in detail the motion of gas in the galaxy NGC 1058 using the very large array (VLA) to map the emission in the 21-cm line. This galaxy is so nearly face-on that the contribution to the line width due to the variation of the rotational velocity across the D-array beam is small compared with the random z-motion of the gas. Researchers confirm results of earlier studies (Lewis 1987, A. and A. Suppl., 63, 515; van der Kruit and Shostak 1984, A. and A., 134, 258) of the galaxy's total neutral hydrogen (HI) and kinematics, including the fact that the rotation curve drops faster than Keplerian at the outer edge of the disk, which is interpreted as a fortuitous twist of the plane of rotation in the outer disk. However, their very high velocity resolution (2.58 km s(exp -1) after Hanning smoothing) coupled with good spatial resolution, allows researchers to measure more accurately the line width, and even to some extent its shape, throughout the disk. One of the most interesting results of this study is the remarkable constancy of the line width in the outer disk. From radius 90 to 210 seconds the Gaussian velocity dispersion (sigma sub nu) of the 21-cm line has a mean value of 5.7 km s(exp -1) (after correcting for the spectral resolution) with a dispersion of less than 0.9 km s(exp -1) (after correcting for the spectral resolution) with a dispersion of less than 0.9 km s(exp -1). Translating this directly into a kinetic temperature (Doppler temperature): T sub Dopp equals 121K (sigma sub mu exp 2/(km s(exp -1) (exp 2) gives 4000 K, with a dispersion of less than 1500 K over the outer disk. This constancy is observed even when comparing the spiral arms versus inter-arm regions, which in the radius range from 100 to 150 seconds the surface density modulates (defined as the ratio N sub peak -N sub trough/N sub peak + N sub trough) from 0.5 to 0.25 in the range 150 to 200 seconds.

High resolution FTIR spectrum of the nu1 band of DCOOD.

PubMed

Goh, K L; Ong, P P; Teo, H H; Tan, T L

2000-04-01

Accurate spectral information on formic acid has wide application to radioastronomy since it was the first organic acid found in interstellar space. In this work, the infrared absorption spectrum of the nu1 band of deuterated formic acid (DCOOD) has been measured on a Bomem DA3.002 Fourier transform spectrometer in the wavenumber region 2560-2690 cm(-1) with a resolution of 0.004 cm(-1). A total of 292 infrared transitions have been assigned in this hybrid type A and B band centred at 2631.8736 +/- 0.0004 cm(-1). The assigned transitions have been fitted to give a set of eight rovibrational constants for the nu1 = 1 state with a standard deviation of 0.00078 cm(-1).

High resolution FTIR spectrum of the ν1 band of DCOOD

NASA Astrophysics Data System (ADS)

Goh, K. L.; Ong, P. P.; Teo, H. H.; Tan, T. L.

2000-04-01

Accurate spectral information on formic acid has wide application to radioastronomy since it was the first organic acid found in interstellar space. In this work, the infrared absorption spectrum of the ν1 band of deuterated formic acid (DCOOD) has been measured on a Bomem DA3.002 Fourier transform spectrometer in the wavenumber region 2560-2690 cm -1 with a resolution of 0.004 cm -1. A total of 292 infrared transitions have been assigned in this hybrid type A and B band centred at 2631.8736±0.0004 cm -1. The assigned transitions have been fitted to give a set of eight rovibrational constants for the v1=1 state with a standard deviation of 0.00078 cm -1.

VizieR Online Data Catalog: Cyanoacetylene (HC3N) infrared spectrum (Bizzocchi+,

NASA Astrophysics Data System (ADS)

Bizzocchi, L.; Tamassia, F.; Laas, J.; Giuliano, B. M.; Degli Esposti, C.; Dore, L.; Melosso, M.; Cane, E.; Pietropolli Charmet, A.; Muller, H. S. P.; Spahn, H.; Belloche, A.; Caselli, P.; Menten, K. M.; Garrod, R. T.

2018-01-01

A substantial amount of new spectroscopic data of HC3N was col in four laboratories located in Bologna, Italy and in Cologne and Munich, Germany. The infrared spectra in the 450-1100cm-1 range were recorded in Bologna using a Bomem DA3.002 Fourier-transform spectrometer. The resolution was generally 0.004cm-1. New mm-wave spectra in selected frequency intervals between 80 and 400GHz were observed in Bologna using a frequency-modulation (FM) mm-wave spectrometer whose details are reported elsewhere (see, e.g., Bizzocchi+ 2016, J/ApJ/820/L26). Further measurements of the sub-mm-wave spectrum of HC3N in the 200-690GHz frequency range were carried out at the Center for Astrochemical Studies (MPE Garching). The measurements performed in Cologne were carried out with leftover samples from previous studies (Yamada+ 1995ZNatA..50.1179Y ; Thorwirth+ 2000JMoSp.204..133T). Further measurements were made using the Cologne Terahertz Spectrometer. See section 2 for further explanations. (2 data files).

Continuous-flow electrophoretic separator for biologicals

NASA Technical Reports Server (NTRS)

Mccreight, L. R.; Griffin, R. N.; Locker, R. J.

1976-01-01

In the near absence of gravity, a continuous-flow type of electrophoretic separator can be operated with a much thicker separation chamber than is possible under 1 g conditions. This should permit either better resolution or shorter separation time per unit of sample. An apparatus to perform experiments on sounding rockets is under development and will be described. The electrophoresis cell is 5 mm thick by 5 cm wide with 10 cm long electrodes. It is supplied with buffer, sample, and coolant at about 4 C through the use of a passive refrigerant system. UV sample detection and provision for recovery and cold storage of up to 50 sample fractions are now being added to the basic unit. A wide range of operating conditions are electronically programmable into the unit, even up to a short time before flight, and a further range of some parameters can be achieved by exchanging power supplies and by changing gears in the motor drive units of the pump. The preliminary results of some separation studies on various biological products using a commercially available electrophoretic separator are also presented.

Thermal structure of the Martian atmosphere retrieved from the IR spectrometry in the 15 μm CO2 band: input to MIRA

NASA Astrophysics Data System (ADS)

Zasova, L. V.; Formisano, V.; Grassi, D.; Igantiev, N. I.; Moroz, V. I.

This paper describes one of the sources of the data concerning the thermal structure of the Martian atmosphere, based on the thermal IR spectrometry method. It allows to investigate the Martian atmosphere below 55 km by retrieving the temperature profiles from the 15 μm CO2 band. This approach enables to reach the vertical resolution of several kilometers and the temperature accuracy of several Kelvins. An aerosol abundance, which influences the temperature profile, is obtained from the continuum of the same spectrum parallel with the temperature profile and is taken into account in the temperature retrieval procedure in a self consistent way. Although this method has the limited vertical resolution, it possesses a significant advantage: the thermal IR spectrometry allows to monitor the temperature profiles with a good coverage both in space and local time. The Planetary Fourier spectrometer on board of Mars Express has the spectral range from 250 to 8000 cm-1 and a high spectral resolution of about 2 cm-1. Vertical temperature profiles retrieval is one of the main scientific goals of the experiment. The important data are expected to be obtained on the vertical thermal structure of the atmosphere, and its dependence on latitude, longitude, season, local time, clouds and dust loadings. These results should give a significant input in the future MIRA, being included in the Chapter “Structure of the atmosphere from the surface to 100 km”.

Electroform replication of grazing incidence X-ray optics. [spaceborne telescopes

NASA Technical Reports Server (NTRS)

Ulmer, M. P.; Purcell, W. R.; Bedford, D.; Simnett, G. R.

1985-01-01

Work to produce mirrors via electroform replication is reported. Work on small (6 cm by 9 cm) cylindrical pieces and on 40 cm long by 12 cm wide Wolter shaped mirrors is summarized. It is shown that electroforming is a viable technique for producing relatively inexpensive grazing incidence X-ray optics, as long as modest resolution (1 min of arc) and size (12 cm diameter by 40 cm long) are specified.

Description and evaluation of the Earth System Regional Climate Model (RegCM-ES)

NASA Astrophysics Data System (ADS)

Farneti, Riccardo; Sitz, Lina; Di Sante, Fabio; Fuentes-Franco, Ramon; Coppola, Erika; Mariotti, Laura; Reale, Marco; Sannino, Gianmaria; Barreiro, Marcelo; Nogherotto, Rita; Giuliani, Graziano; Graffino, Giorgio; Solidoro, Cosimo; Giorgi, Filippo

2017-04-01

The increasing availability of satellite remote sensing data, of high temporal frequency and spatial resolution, has provided a new and enhanced view of the global ocean and atmosphere, revealing strong air-sea coupling processes throughout the ocean basins. In order to obtain an accurate representation and better understanding of the climate system, its variability and change, the inclusion of all mechanisms of interaction among the different sub-components, at high temporal and spatial resolution, becomes ever more desirable. Recently, global coupled models have been able to progressively refine their horizontal resolution to attempt to resolve smaller-scale processes. However, regional coupled ocean-atmosphere models can achieve even finer resolutions and provide additional information on the mechanisms of air-sea interactions and feedbacks. Here we describe a new, state-of-the-art, Earth System Regional Climate Model (RegCM-ES). RegCM-ES presently includes the coupling between atmosphere, ocean, land surface and sea-ice components, as well as an hydrological and ocean biogeochemistry model. The regional coupled model has been implemented and tested over some of the COordinated Regional climate Downscaling Experiment (CORDEX) domains. RegCM-ES has shown improvements in the representation of precipitation and SST fields over the tested domains, as well as realistic representations of coupled air-sea processes and interactions. The RegCM-ES model, which can be easily implemented over any regional domain of interest, is open source making it suitable for usage by the large scientific community.

Electromagnetic diagnostics of ECR-Ion Sources plasmas: optical/X-ray imaging and spectroscopy

NASA Astrophysics Data System (ADS)

Mascali, D.; Castro, G.; Altana, C.; Caliri, C.; Mazzaglia, M.; Romano, F. P.; Leone, F.; Musumarra, A.; Naselli, E.; Reitano, R.; Torrisi, G.; Celona, L.; Cosentino, L. G.; Giarrusso, M.; Gammino, S.

2017-12-01

Magnetoplasmas in ECR-Ion Sources are excited from gaseous elements or vapours by microwaves in the range 2.45-28 GHz via Electron Cyclotron Resonance. A B-minimum, magnetohydrodynamic stable configuration is used for trapping the plasma. The values of plasma density, temperature and confinement times are typically ne= 1011-1013 cm-3, 01 eV

The High-Resolution, Jet-cooled Infrared Spectrum of Pentafluoroethane

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

Goss, Lisa M.; Hess, Whitney R.; Blake, Thomas A.

The jet-cooled spectrum of pentafluoroethane (C2HF5) has been recorded between 1100 and 1325 cm-1 at a resolution of 0.0022 cm-1. A rotational temperature of approximately 10 K was achieved by expanding 50 Torr of C2HF5 in 500 Torr of helium. Transitions belonging to five different fundamental vibrations have been assigned and fit to a Watson Hamiltonian: the m3 band at 1309.880494(189) cm-1, m4 at 1200.734645(67) cm-1, m5 at 1142.78147(33) cm-1, m13 at 1223.334098(115) cm-1, and m14 at 1147.394185(163) cm-1. The fit of the m4 band has an rms deviation of 0.000436 cm-1 compared to the uncertainty in the experimental linemore » position of 0.0002 cm-1. Satisfactory fits were achieved for the other four bands (m3, m5, m13, m14) at this cold temperature, with most of the centrifugal distortion constants fixed at the ground state values. Joint fits with previous work were attempted for the m4 and m13, successfully in the former case and unsuccessfully in the latter.« less

Fourier transform infrared spectroscopy of D212CO in the 2500-4500 cm-1 region and the first rovibrational analysis of its v2 = 2 state

NASA Astrophysics Data System (ADS)

A'dawiah, Rabia'tul; Tan, T. L.; Ng, L. L.

2018-03-01

A low-resolution (0.5 cm-1) Fourier transform infrared (FTIR) spectrum of formaldehyde-d2 (D212CO) in the 2500-4500 cm-1 region was recorded to study the combination bands in this region. The bands ν2 +ν4,ν2 +ν6 , ν2 +ν3 , ν1 +ν2 , ν2 +ν5 , 3ν3 , 2ν2 and 2ν5 were identified and their band centers (with an uncertainty of ± 0.1 cm-1) and band types were determined. Furthermore, the high-resolution FTIR spectrum of the 2ν2 overtone band (3315-3440 cm-1) of D212CO was recorded at an unapodized resolution of 0.0063 cm-1 and its infrared lines were analyzed. A total of 970 rovibrational transitions have been assigned and fitted up to J‧ = 35 and Ka‧ = 14 using the Watson's A-reduced Hamiltonian in the Ir representation. Upper state (v2 = 2) rovibrational constants inclusive of three rotational and five quartic centrifugal distortion constants were accurately determined for the first time. The band center of the 2ν2 band was determined as 3385.200666 ± 0.000035 cm-1. The rms deviation of the rovibrational fit was 0.00093 cm-1. From the fitting of 451 ground state combination differences (GSCDs) of D212CO which were derived from the infrared transitions of the 2ν2 band of this work, together with 360 microwave frequencies from a previous study, new and accurate ground state constants of D212CO up to three octic terms were obtained. The combination and overtone bands and the newly assigned high-resolution infrared lines of the 2ν2 band in the 2500-4500 cm-1 region can be used to detect D212CO in this infrared region. In addition, the results derived from this study give information on the rovibrational molecular structure of D212CO.

The 2ν2 bands of H212CO and H213CO by high-resolution FTIR spectroscopy

NASA Astrophysics Data System (ADS)

Tan, T. L.; A'dawiah, Rabia'tul; Ng, L. L.

2017-10-01

The Fourier transform infrared (FTIR) absorption spectra of the 2ν2 overtone bands of formaldehyde H212CO and its isotopologue H213CO were recorded at an unapodized resolution of 0.0063 cm-1 in the 3300-3540 cm-1 region. Upper state (v2 = 2) rovibrational up to two sextic centrifugal distortion constants were accurately determined for both H212CO and H213CO. A total of 533 unperturbed infrared transitions of H212CO and 466 unperturbed infrared transitions of H212CO were assigned and fitted with rms deviations of 0.0012 cm-1 and 0.00084 cm-1 respectively using Watson's A-reduced Hamiltonian in the Ir representation. Analysis of new transitions for H212CO measured in this work yielded upper state constants with greater accuracy than previously reported. The infrared transitions of the 2ν2 band of H213CO were measured for the first time. The band center of the A-type 2ν2 band of H212CO was found to be 3471.71403 ± 0.00012 cm-1 and that of H213CO was 3396.628983 ± 0.000083 cm-1. Furthermore, the newly assigned high-resolution infrared lines of the 2ν2 bands in the 3300-3540 cm-1 region can be useful in detecting the H212CO and H213CO molecules in this IR region.

Assessment of two versions of regional climate model in simulating the Indian Summer Monsoon over South Asia CORDEX domain

NASA Astrophysics Data System (ADS)

Pattnayak, K. C.; Panda, S. K.; Saraswat, Vaishali; Dash, S. K.

2018-04-01

This study assess the performance of two versions of Regional Climate Model (RegCM) in simulating the Indian summer monsoon over South Asia for the period 1998 to 2003 with an aim of conducting future climate change simulations. Two sets of experiments were carried out with two different versions of RegCM (viz. RegCM4.2 and RegCM4.3) with the lateral boundary forcings provided from European Center for Medium Range Weather Forecast Reanalysis (ERA-interim) at 50 km horizontal resolution. The major updates in RegCM4.3 in comparison to the older version RegCM4.2 are the inclusion of measured solar irradiance in place of hardcoded solar constant and additional layers in the stratosphere. The analysis shows that the Indian summer monsoon rainfall, moisture flux and surface net downward shortwave flux are better represented in RegCM4.3 than that in the RegCM4.2 simulations. Excessive moisture flux in the RegCM4.2 simulation over the northern Arabian Sea and Peninsular India resulted in an overestimation of rainfall over the Western Ghats, Peninsular region as a result of which the all India rainfall has been overestimated. RegCM4.3 has performed well over India as a whole as well as its four rainfall homogenous zones in reproducing the mean monsoon rainfall and inter-annual variation of rainfall. Further, the monsoon onset, low-level Somali Jet and the upper level tropical easterly jet are better represented in the RegCM4.3 than RegCM4.2. Thus, RegCM4.3 has performed better in simulating the mean summer monsoon circulation over the South Asia. Hence, RegCM4.3 may be used to study the future climate change over the South Asia.

Early results from the Far Infrared Absolute Spectrophotometer (FIRAS)

NASA Technical Reports Server (NTRS)

Mather, J. C.; Cheng, E. S.; Shafer, R. A.; Eplee, R. E.; Isaacman, R. B.; Fixsen, D. J.; Read, S. M.; Meyer, S. S.; Weiss, R.; Wright, E. L.

1991-01-01

The Far Infrared Absolute Spectrophotometer (FIRAS) on the Cosmic Background Explorer (COBE) mapped 98 percent of the sky, 60 percent of it twice, before the liquid helium coolant was exhausted. The FIRAS covers the frequency region from 1 to 100/cm with a 7 deg angular resolution. The spectral resolution is 0.2/cm for frequencies less than 20/cm and 0.8/cm for higher frequencies. Preliminary results include: a limit on the deviations from a Planck curve of 1 percent of the peak brightness from 1 to 20/cm, a temperature of 2.735 +/- 0.06 K, a limit on the Comptonization parameter y of 0.001, on the chemical potential parameter mu of 0.01, a strong limit on the existence of a hot smooth intergalactic medium, and a confirmation that the dipole anisotropy spectrum is that of a Doppler shifted blackbody.

A space bourne crystal diffraction telescope for the energy range of nuclear transitions

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

von Ballmoos, P.; Naya, J.E.; Albernhe, F.

1995-10-01

Recent experimental work of the Toulouse-Argonne collaboration has opened for perspective of a focusing gamma-ray telescope operating in the energy range of nuclear transitions, featuring unprecedented sensitivity, angular and energy resolution. The instrument consists of a tunable crystal diffraction lens situated on a stabilized spacecraft, focusing gamma-rays onto a small array of Germanium detectors perched on an extendible boom. While the weight of such an instrument is less than 500 kg, it features an angular resolution of 15 in., an energy resolution of 2 keV and a 3 {sigma} narrow line sensitivity of a few times 10{sup {minus}7} photons s{supmore » {minus}1} cm{sup {minus}2} (10{sup 6} sec observation). This instrumental concept permits observation of any identified source at any selected line-energy in a range of typically 200 keV to 1300 keV. The resulting ``sequential`` operation mode makes sites of explosive nucleosynthesis natural scientific objectives for such a telescope: the nuclear lines of extragalactic supernovae ({sup 56}Ni, {sup 44}Ti, {sup 60}Fe) and galactic novae (p{sup {minus}}p{sup +} line, {sup 7}Be) are accessible to observation, one at a time, due to the erratic appearance and the sequence of half-lifes of these events. Other scientific objectives, include the narrow 511 keV line from galactic broad class annihilators (such as 1E1740-29, nova musca) and possible redshifted annihilation lines from AGN`s.« less

Multifaceted Therapeutic Benefits of Factors Derived From Dental Pulp Stem Cells for Mouse Liver Fibrosis.

PubMed

Hirata, Marina; Ishigami, Masatoshi; Matsushita, Yoshihiro; Ito, Takanori; Hattori, Hisashi; Hibi, Hideharu; Goto, Hidemi; Ueda, Minoru; Yamamoto, Akihito

2016-10-01

: Chronic liver injury from various causes often results in liver fibrosis (LF). Although the liver possesses endogenous tissue-repairing activities, these can be overcome by sustained inflammation and excessive fibrotic scar formation. Advanced LF leads to irreversible cirrhosis and subsequent liver failure and/or hepatic cancer. Here, using the mouse carbon tetrachloride (CCl 4 )-induced LF model, we showed that a single intravenous administration of stem cells derived from human exfoliated deciduous teeth (SHEDs) or of SHED-derived serum-free conditioned medium (SHED-CM) resulted in fibrotic scar resolution. SHED-CM suppressed the gene expression of proinflammatory mediators, such as TNF-α, IL-1β, and iNOS, and eliminated activated hepatic stellate cells by inducing their apoptosis, but protected parenchymal hepatocytes from undergoing apoptosis. In addition, SHED-CM induced tissue-repairing macrophages that expressed high levels of the profibrinolytic factor, matrix metalloproteinase 13. Furthermore, SHED-CM suppressed the CCl 4 -induced apoptosis of primary cultured hepatocytes. SHED-CM contained a high level of hepatocyte growth factor (HGF). Notably, HGF-depleted SHED-CM (dHGF-CM) did not suppress the proinflammatory response or resolve fibrotic scarring. Furthermore, SHED-CM, but not dHGF-CM, inhibited CCl 4 -induced hepatocyte apoptosis. These results suggest that HGF plays a central role in the SHED-CM-mediated resolution of LF. Taken together, our findings suggest that SHED-CM provides multifaceted therapeutic benefits for the treatment of LF. This study demonstrated that a single intravenous administration of stem cells from human exfoliated deciduous teeth (SHEDs) or of the serum-free conditioned medium (CM) derived from SHEDs markedly improved mouse liver fibrosis (LF). SHED-CM suppressed chronic inflammation, eliminated activated hepatic stellate cells by inducing their apoptosis, protected hepatocytes from undergoing apoptosis, and induced differentiation of tissue-repairing macrophages expressing high levels of the profibrinolytic factor matrix metalloproteinase 13. Furthermore, hepatocyte growth factor played a central role in the SHED-CM-mediated resolution of LF. This is the first report demonstrating the multifaceted therapeutic benefits of secreted factors derived from SHEDs for LF. ©AlphaMed Press.

Peak capacity, peak-capacity production rate, and boiling point resolution for temperature-programmed GC with very high programming rates

PubMed

Grall; Leonard; Sacks

2000-02-01

Recent advances in column heating technology have made possible very fast linear temperature programming for high-speed gas chromatography. A fused-silica capillary column is contained in a tubular metal jacket, which is resistively heated by a precision power supply. With very rapid column heating, the rate of peak-capacity production is significantly enhanced, but the total peak capacity and the boiling-point resolution (minimum boiling-point difference required for the separation of two nonpolar compounds on a nonpolar column) are reduced relative to more conventional heating rates used with convection-oven instruments. As temperature-programming rates increase, elution temperatures also increase with the result that retention may become insignificant prior to elution. This results in inefficient utilization of the down-stream end of the column and causes a loss in the rate of peak-capacity production. The rate of peak-capacity production is increased by the use of shorter columns and higher carrier gas velocities. With high programming rates (100-600 degrees C/min), column lengths of 6-12 m and average linear carrier gas velocities in the 100-150 cm/s range are satisfactory. In this study, the rate of peak-capacity production, the total peak capacity, and the boiling point resolution are determined for C10-C28 n-alkanes using 6-18 m long columns, 50-200 cm/s average carrier gas velocities, and 60-600 degrees C/min programming rates. It was found that with a 6-meter-long, 0.25-mm i.d. column programmed at a rate of 600 degrees C/min, a maximum peak-capacity production rate of 6.1 peaks/s was obtained. A total peak capacity of about 75 peaks was produced in a 37-s long separation spanning a boiling-point range from n-C10 (174 degrees C) to n-C28 (432 degrees C).

Non-contact and noise tolerant heart rate monitoring using microwave doppler sensor and range imagery.

PubMed

Matsunag, Daichi; Izumi, Shintaro; Okuno, Keisuke; Kawaguchi, Hiroshi; Yoshimoto, Masahiko

2015-01-01

This paper describes a non-contact and noise-tolerant heart beat monitoring system. The proposed system comprises a microwave Doppler sensor and range imagery using Microsoft Kinect™. The possible application of the proposed system is a driver health monitoring. We introduce the sensor fusion approach to minimize the heart beat detection error. The proposed algorithm can subtract a body motion artifact from Doppler sensor output using time-frequency analysis. The body motion artifact is a crucially important problem for biosignal monitoring using microwave Doppler sensor. The body motion speed is obtainable from range imagery, which has 5-mm resolution at 30-cm distance. Measurement results show that the success rate of the heart beat detection is improved about 75% on average when the Doppler wave is degraded by the body motion artifact.

Performance and applications of a hypertemporal hyperspectral Fourier-transform infrared spectroradiometer

NASA Astrophysics Data System (ADS)

King, Bruce H.; Ellis, Thomas; Old, Tom E.

2009-05-01

A fast-scanning, high-resolution FTIR spectroradiometer has been designed and built for use in remote sensing, stand-off detection, and spectral-temporal characterization of fast, energetic infrared events. The instrument design uses a Michelson-type interferometer with a rotary modulator which is capable of continuous measurement of infrared spectra at a rate of 1000 scans per second with 4 cm-1 resolution in the 2 - 25 micron spectral range. Sensitivity, spectral accuracy, and radiometric precision are discussed along with specific design parameters. This instrument can be used for passive sensing as a stand-alone sensor, or for active sensing as a receiver when used in conjunction with a highenergy excitation source such as a laser. Applications include muzzle flash signature measurement, ordnance detonation characterization, missile plume identification, and rocket motor combustion diagnostics.

Carbon dioxide and methane fluxes from the transitional zone of a Virginia ephemeral wetland

NASA Astrophysics Data System (ADS)

Atkins, J. W.; Epstein, H. E.; Welsch, D. L.

2014-12-01

The spatial and temporal controls mediating the switch between anaerobic and aerobic respiration within soils located in transitional zones adjacent to ephemeral wetlands remains unclear. As ephemeral wetlands dry down, a soil moisture gradient develops in adjacent transitional zones resulting in changes to the soil environment—moving from anoxic to oxic conditions. Under oxic conditions, aerobic decomposition and CO2 fluxes should dominate, while under anoxic conditions, anaerobic decomposition and CH4 emissions should be more prominent. To investigate the spatial controls and temporal dynamics of anaerobic and aerobic respiration we ran three 20 m transects starting from the late spring peak wetland edge (June 1, 2014 max. lake extent) of Lake Arnold, an ephemeral wetland located at Blandy Experimental Farm in Boyce, Virginia. At 10 m intervals along each transect, high-resolution soil moisture and temperature sensors were installed at three depth levels in the soil (5 cm, 20 cm, and 50 cm). Soil surface CO2 efflux was measured weekly at 5 m intervals using a portable, infra-red gas analyzer and surface chamber (EGM-4 and SRC-1; PP Systems; Amherst, MA). CH4 emissions were sampled weekly using a non-steady state chamber at 10 m intervals along each transect and analyzed in the lab using gas chromatography. Redox potential was measured weekly at two soil depths (5 cm and 20 cm) at 5 m intervals using platinum electrodes and a Ag/Cl reference electrode. Lake Arnold water levels decreased at a rate of 18.16 mm day-1 during the month of July. Preliminary results show a distinct drop in soil moisture at 5 and 20 cm depths at the 0 and 10 m distances along each transect. At 50 cm, soil moisture shows no distinct trend. Late July measurements of redox potential ranged from -196 mV to 865 mV and was correlated with soil moisture (R2 = 0.52). Rates of soil CO2 efflux were diminished at volumetric water contents (VWC) above 45% (ranging from 2.45 - 7.3 µmol CO2 m-2 sec-1). Below 45% VWC, soil CO2 efflux rates ranged from 4.5 - 9.6 µmol CO2 m-2 sec-1.

High-Resolution IR Absorption Spectroscopy of Polycyclic Aromatic Hydrocarbons in the 3-micrometers Region: Role of Periphery

NASA Technical Reports Server (NTRS)

Maltseva, Elena; Petrignani, Annemieke; Candian, Alessandra; Mackie, Cameron J.; Huang, Xinchuan; Lee, Timothy J.; Tielens, Alexander G. G. M.; Oomens, Jos; Buma, Wybren Jan

2017-01-01

In this work we report on high-resolution IR absorption studies that provide a detailed view on how the peripheral structure of irregular polycyclic aromatic hydrocarbons (PAHs) affects the shape and position of their 3-micrometers absorption band. To this purpose we present mass-selected, high-resolution absorption spectra of cold and isolated phenanthrene, pyrene, benz[a]antracene, chrysene, triphenylene, and perylene molecules in the 2950-3150 per cm range. The experimental spectra are compared with standard harmonic calculations, and anharmonic calculations using a modified version of the SPECTRO program that incorporates a Fermi resonance treatment utilizing intensity redistribution. We show that the 3-micrometers region is dominated by the effects of anharmonicity, resulting in many more bands than would have been expected in a purely harmonic approximation. Importantly, we find that anharmonic spectra as calculated by SPECTRO are in good agreement with the experimental spectra. Together with previously reported high-resolution spectra of linear acenes, the present spectra provide us with an extensive dataset of spectra of PAHs with a varying number of aromatic rings, with geometries that range from open to highly-condensed structures, and featuring CH groups in all possible edge configurations. We discuss the astrophysical implications of the comparison of these spectra on the interpretation of the appearance of the aromatic infrared 3-micrometers band, and on features such as the two-component emission character of this band and the 3-micrometers emission plateau.

High-resolution IR Absorption Spectroscopy of Polycyclic Aromatic Hydrocarbons in the 3 μm Region: Role of Periphery

NASA Astrophysics Data System (ADS)

Maltseva, Elena; Petrignani, Annemieke; Candian, Alessandra; Mackie, Cameron J.; Huang, Xinchuan; Lee, Timothy J.; Tielens, Alexander G. G. M.; Oomens, Jos; Buma, Wybren Jan

2016-11-01

In this work we report on high-resolution IR absorption studies that provide a detailed view on how the peripheral structure of irregular polycyclic aromatic hydrocarbons (PAHs) affects the shape and position of their 3 μm absorption band. For this purpose, we present mass-selected, high-resolution absorption spectra of cold and isolated phenanthrene, pyrene, benz[a]antracene, chrysene, triphenylene, and perylene molecules in the 2950-3150 cm-1 range. The experimental spectra are compared with standard harmonic calculations and anharmonic calculations using a modified version of the SPECTRO program that incorporates a Fermi resonance treatment utilizing intensity redistribution. We show that the 3 μm region is dominated by the effects of anharmonicity, resulting in many more bands than would have been expected in a purely harmonic approximation. Importantly, we find that anharmonic spectra as calculated by SPECTRO are in good agreement with the experimental spectra. Together with previously reported high-resolution spectra of linear acenes, the present spectra provide us with an extensive data set of spectra of PAHs with a varying number of aromatic rings, with geometries that range from open to highly condensed structures, and featuring CH groups in all possible edge configurations. We discuss the astrophysical implications of the comparison of these spectra on the interpretation of the appearance of the aromatic infrared 3 μm band, and on features such as the two-component emission character of this band and the 3 μm emission plateau.

Does Dynamical Downscaling Introduce Novel Information in Climate Model Simulations of Recipitation Change over a Complex Topography Region?

NASA Technical Reports Server (NTRS)

Tselioudis, George; Douvis, Costas; Zerefos, Christos

2012-01-01

Current climate and future climate-warming runs with the RegCM Regional Climate Model (RCM) at 50 and 11 km-resolutions forced by the ECHAM GCM are used to examine whether the increased resolution of the RCM introduces novel information in the precipitation field when the models are run for the mountainous region of the Hellenic peninsula. The model results are inter-compared with the resolution of the RCM output degraded to match that of the GCM, and it is found that in both the present and future climate runs the regional models produce more precipitation than the forcing GCM. At the same time, the RCM runs produce increases in precipitation with climate warming even though they are forced with a GCM that shows no precipitation change in the region. The additional precipitation is mostly concentrated over the mountain ranges, where orographic precipitation formation is expected to be a dominant mechanism. It is found that, when examined at the same resolution, the elevation heights of the GCM are lower than those of the averaged RCM in the areas of the main mountain ranges. It is also found that the majority of the difference in precipitation between the RCM and the GCM can be explained by their difference in topographic height. The study results indicate that, in complex topography regions, GCM predictions of precipitation change with climate warming may be dry biased due to the GCM smoothing of the regional topography.

SU-E-CAMPUS-T-02: Exploring Radiation Acoustics CT Dosimeter Design Aspects for Proton Therapy

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

Alsanea, F; Moskvin, V; Stantz, K

2014-06-15

Purpose: Investigate the design aspects and imaging dose capabilities of the Radiation Acoustics Computed Tomography (RA CT) dosimeter for Proton induced acoustics, with the objective to characterize a pulsed pencil proton beam. The focus includes scanner geometry, transducer array, and transducer bandwidth on image quality. Methods: The geometry of the dosimeter is a cylindrical water phantom (length 40cm, radius 15cm) with 71 ultrasound transducers placed along the length and end of the cylinder to achieve a weighted set of projections with spherical sampling. A 3D filtered backprojection algorithm was used to reconstruct the dosimetric images and compared to MC dosemore » distribution. First, 3D Monte Carlo (MC) Dose distributions for proton beam energies (range of 12cm, 16cm, 20cm, and 27cm) were used to simulate the acoustic pressure signal within this scanner for a pulsed proton beam of 1.8x107 protons, with a pulse width of 1 microsecond and a rise time of 0.1 microseconds. Dose comparison within the Bragg peak and distal edge were compared to MC analysis, where the integrated Gaussian was used to locate the 50% dose of the distal edge. To evaluate spatial fidelity, a set of point sources within the scanner field of view (15×15×15cm3) were simulated implementing a low-pass bandwidth response function (0 to 1MHz) equivalent to a multiple frequency transducer array, and the FWHM of the point-spread-function determined. Results: From the reconstructed images, RACT and MC range values are within 0.5mm, and the average variation of the dose within the Bragg peak are within 2%. The spatial resolution tracked with transducer bandwidth and projection angle sampling, and can be kept at 1.5mm. Conclusion: This design is ready for fabrication to start acquiring measurements. The 15 cm FOV is an optimum size for imaging dosimetry. Currently, simulations comparing transducer sensitivity, bandwidth, and proton beam parameters are being evaluated to assess signal-to-noise.« less

Low-density InP-based quantum dots emitting around the 1.5 μm telecom wavelength range

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

Yacob, M.; Reithmaier, J. P.; Benyoucef, M., E-mail: m.benyoucef@physik.uni-kassel.de

The authors report on low-density InAs quantum dots (QDs) grown on AlGaInAs surfaces lattice matched to InP using post-growth annealing by solid-source molecular beam epitaxy. Clearly spatially separated QDs with a dot density of about 5 × 10{sup 8} cm{sup −2} are obtained by using a special capping technique after the dot formation process. High-resolution micro-photoluminescence performed on optimized QD structures grown on distributed Bragg reflector exhibits single QD emissions around 1.5 μm with narrow excitonic linewidth below 50 μeV, which can be used as single photon source in the telecom wavelength range.

A laser frequency comb that enables radial velocity measurements with a precision of 1 cm s(-1).

PubMed

Li, Chih-Hao; Benedick, Andrew J; Fendel, Peter; Glenday, Alexander G; Kärtner, Franz X; Phillips, David F; Sasselov, Dimitar; Szentgyorgyi, Andrew; Walsworth, Ronald L

2008-04-03

Searches for extrasolar planets using the periodic Doppler shift of stellar spectral lines have recently achieved a precision of 60 cm s(-1) (ref. 1), which is sufficient to find a 5-Earth-mass planet in a Mercury-like orbit around a Sun-like star. To find a 1-Earth-mass planet in an Earth-like orbit, a precision of approximately 5 cm s(-1) is necessary. The combination of a laser frequency comb with a Fabry-Pérot filtering cavity has been suggested as a promising approach to achieve such Doppler shift resolution via improved spectrograph wavelength calibration, with recent encouraging results. Here we report the fabrication of such a filtered laser comb with up to 40-GHz (approximately 1-A) line spacing, generated from a 1-GHz repetition-rate source, without compromising long-term stability, reproducibility or spectral resolution. This wide-line-spacing comb, or 'astro-comb', is well matched to the resolving power of high-resolution astrophysical spectrographs. The astro-comb should allow a precision as high as 1 cm s(-1) in astronomical radial velocity measurements.

A two-parameter scintillation spectrometer system for measurement of secondary proton, deuteron, and triton distributions from materials under 558-MeV-proton irradiation

NASA Technical Reports Server (NTRS)

Beck, S. M.

1975-01-01

A two-parameter scintillation spectrometer system developed and used to obtain proton, deuteron, and triton double differential cross sections from materials under 558-MeV-proton irradiation is described. The system measures both the time of flight of secondary particles over a 488-cm flight path and the energy deposited in a scintillator, 12.7 cm in diameter and 30.48 cm long. The time resolution of the system is 0.39 nsec. The calculated energy resolution based on this time resolution varies with energy from 1.6 precent to 7.75 percent for 50- and 558-MeV protons. Various systematic and statistical errors are evaluated, and the double differential cross sections for secondary proton and deutron production at 20 deg from a 2.35 g/sq cm thick beryllium target are shown as an example of the results obtainable with this system. The uncertainly in the cross sections for secondary protons varies with particle energy from approximately + or - 9 percent at 50 MeV to approximately + or - 11 percent at 558 MeV.

Miniature spectrometer and beam splitter for an optical coherence tomography on a silicon chip.

PubMed

Akca, B I; Považay, B; Alex, A; Wörhoff, K; de Ridder, R M; Drexler, W; Pollnau, M

2013-07-15

Optical coherence tomography (OCT) has enabled clinical applications that revolutionized in vivo medical diagnostics. Nevertheless, its current limitations owing to cost, size, complexity, and the need for accurate alignment must be overcome by radically novel approaches. Exploiting integrated optics, we assemble the central components of a spectral-domain OCT system on a silicon chip. The spectrometer comprises an arrayed-waveguide grating with 136-nm free spectral range and 0.21-nm wavelength resolution. The beam splitter is realized by a non-uniform adiabatic coupler with its 3-dB splitting ratio being nearly constant over 150 nm. With this device whose overall volume is 0.36 cm(3) we demonstrate high-quality in vivo imaging in human skin with 1.4-mm penetration depth, 7.5-µm axial resolution, and a signal-to-noise ratio of 74 dB. Considering the reasonable performance of this early OCT on-a-chip system and the anticipated improvements in this technology, a completely different range of devices and new fields of applications may become feasible.

A Novel Intracranial Pressure Readout Circuit for Passive Wireless LC Sensor.

PubMed

Wang, Fa; Zhang, Xuan; Shokoueinejad, Mehdi; Iskandar, Bermans J; Medow, Joshua E; Webster, John G

2017-10-01

We present a wide frequency range, low cost, wireless intracranial pressure monitoring system, which includes an implantable passive sensor and an external reader. The passive sensor consists of two spiral coils and transduces the pressure change to a resonant frequency shift. The external portable reader reads out the sensor's resonant frequency over a wide frequency range (35 MHz-2.7 GHz). We propose a novel circuit topology, which tracks the system's impedance and phase change at a high frequency with low-cost components. This circuit is very simple and reliable. A prototype has been developed, and measurement results demonstrate that the device achieves a suitable measurement distance (>2 cm), sufficient sample frequency (>6 Hz), fine resolution, and good measurement accuracy for medical practice. Responsivity of this prototype is 0.92 MHz/mmHg and resolution is 0.028 mmHg. COMSOL specific absorption rate simulation proves that this system is safe. Considerations to improve the device performance have been discussed, which include the size of antenna, the power radiation, the Analog-to-digital converter (ADC) choice, and the signal processing algorithm.

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

Plautz, Tia E.; Johnson, R. P.; Sadrozinski, H. F.-W.

Purpose: To characterize the modulation transfer function (MTF) of the pre-clinical (phase II) head scanner developed for proton computed tomography (pCT) by the pCT collaboration. To evaluate the spatial resolution achievable by this system. Methods: Our phase II proton CT scanner prototype consists of two silicon telescopes that track individual protons upstream and downstream from a phantom, and a 5-stage scintillation detector that measures a combination of the residual energy and range of the proton. Residual energy is converted to water equivalent path length (WEPL) of the protons in the scanned object. The set of WEPL values and associated pathsmore » of protons passing through the object over a 360° angular scan is processed by an iterative parallelizable reconstruction algorithm that runs on GP-GPU hardware. A custom edge phantom composed of water-equivalent polymer and tissue-equivalent material inserts was constructed. The phantom was first simulated in Geant4 and then built to perform experimental beam tests with 200 MeV protons at the Northwestern Medicine Chicago Proton Center. The oversampling method was used to construct radial and azimuthal edge spread functions and modulation transfer functions. The spatial resolution was defined by the 10% point of the modulation transfer function in units of lp/cm. Results: The spatial resolution of the image was found to be strongly correlated with the radial position of the insert but independent of the relative stopping power of the insert. The spatial resolution varies between roughly 4 and 6 lp/cm in both the the radial and azimuthal directions depending on the radial displacement of the edge. Conclusion: The amount of image degradation due to our detector system is small compared with the effects of multiple Coulomb scattering, pixelation of the image and the reconstruction algorithm. Improvements in reconstruction will be made in order to achieve the theoretical limits of spatial resolution.« less

Thermal structure of the Martian atmosphere retrieved from the IR- spectrometry in the 15 mkm CO2 band

NASA Astrophysics Data System (ADS)

Zasova, L.; Formisano, V.; Grassi, D.; Igantiev, N.; Moroz, V.

Thermal IR spectrometry is one of the methods of the Martian atmosphere investigation below 55 km. The temperature profiles retrieved from the 15 μm CO2 band may be used for MIRA database. This approach gives the vertical resolution of several kilometers and accuracy of several Kelvins. An aerosol abundance, which influences the temperature profiles, is obtained from the continuum of the same spectrum. It is taken into account in the temperature retrieval procedure in a self- consistent way. Although this method has limited vertical resolution it possesses some advantages. For example, the radio occultation method gives the temperature profiles with higher spectral resolution, but the radio observations are sparse in space and local time. Direct measurements, which give the most accurate results, enable to obtain the temperature profiles only for some chosen points (landing places). Actually, the thermal IR-spectrometry is the only method, which allows to monitor the temperature profiles with good coverage both in space and local time. The first measurements of this kind were fulfilled by IRIS, installed on board of Mariner 9. This spectrometer was characterized by rather high spectral resolution (2.4 cm-1). The temperature profiles vs. local time dependencies for different latitudes and seasons were retrieved, including dust storm conditions, North polar night, Tharsis volcanoes. The obtained temperature profiles have been compared with the temperature profiles for the same conditions, taken from Climate Data Base (European GCM). The Planetary Fourier Spectrometer onboard Mars Express (which is planned to be launched in 2003) has the spectral range 1.2-45 μm and spectral resolution of 1.5 cm- 1. Temperature retrieval is one of the main scientific goals of the experiment. It opens a possibility to get a series of temperature profiles taken for different conditions, which can later be used in MIRA producing.

Synchrotron Spectroscopy and Torsional Structure of the Csh-Bending and CH3-ROCKING Bands of Methyl Mercaptan

NASA Astrophysics Data System (ADS)

Lees, Ronald M.; Xu, Li-Hong; Billinghurst, Brant E.

2016-06-01

The Fourier transform spectra of the CSH-bending and CH3-rocking infrared bands of CH3SH have been investigated at 0.001 cm-1 resolution employing synchrotron radiation at the Canadian Light Source in Saskatoon. The relative band strengths and structures are remarkably different from those for the analogous CH3OH relative, with the CSH bend being very weak and both the in-plane and out-of-plane CH3 rocks being strong with comparable intensities. The CSH bend, centered at 801.5 cm-1, has parallel a-type character with no detectable b-type component. The out-of-plane CH3 rock at 957.0 cm-1 is a purely c-type perpendicular band, whereas the in-plane rock around 1074 cm-1 is of mixed a/b character. The K-reduced vt = 0 sub-state origins for the CSH bend follow the normal oscillatory torsional pattern as a function of K with an amplitude of 0.362 cm-1, as compared to 0.653 cm-1 for the ground state and 0.801 cm-1 for the C-S stretching mode. The torsional energy curves for the out-of-plane rock are also well-behaved but are inverted, with an amplitude of 1.33 cm-1. In contrast, the sub-state origins for the in-plane rock do not display a clear oscillatory structure but are scattered over a range of about 2 cm-1, with indications of some significant perturbations. The assignments for the three bands all extend up to about K = 10 and are well-determined from GSCD relations, particularly for the a/b in-plane rock for which ΔK = 0, +1 and -1 transitions are all observed.

High-resolution X-Ray Spectroscopy of the Seyfert 1 Galaxy Mrk 1040. Revealing the Failed Nuclear Wind with Chandra

NASA Astrophysics Data System (ADS)

Reeves, J. N.; Braito, V.; Behar, E.; Fischer, T. C.; Kraemer, S. B.; Lobban, A.; Nardini, E.; Porquet, D.; Turner, T. J.

2017-03-01

High-resolution X-ray spectroscopy of the warm absorber in the nearby X-ray bright Seyfert 1 galaxy Mrk 1040 is presented. The observations were carried out in the 2013-2014 timeframe using the Chandra High Energy Transmission Grating with a total exposure of 200 ks. A multitude of absorption lines from Ne, Mg, and Si are detected from a wide variety of ionization states. In particular, the detection of inner K-shell absorption lines from Ne, Mg, and Si, from charge states ranging from F-like to Li-like ions, suggests the presence of a substantial amount of low-ionization absorbing gas, illuminated by a steep soft X-ray continuum. The observations reveal at least three warm absorbing components ranging in ionization parameter from {log}(ξ /{erg} {cm} {{{s}}}-1)=0{--}2 and with column densities of {N}{{H}}=1.5{--}4.0× {10}21 cm-2. The velocity profiles imply that the outflow velocities of the absorbing gas are low and within ±100 km s-1 of the systemic velocity of Mrk 1040, which suggests that any outflowing gas may have stalled in this AGN on large enough scales. The warm absorber is likely located far from the black hole, within 300 pc of the nucleus, and is spatially coincident with emission from an extended narrow-line region as seen in the Hubble Space Telescope images. The iron K-band spectrum reveals only narrow emission lines, with Fe Kα at 6.4 keV consistent with originating from reflection off Compton-thick pc-scale reprocessing gas.

Development of SMAP Mission Cal/Val Activities

NASA Technical Reports Server (NTRS)

Colliander, A.; Jackson, T.; Kimball, J.; Cosh, M.; Spencer, M.; Entekhabi, D.; Njoku, E.; ONeill, P.

2010-01-01

The Soil Moisture Active Passive (SMAP) mission is a NASA directed mission to map global land surface soil moisture and freeze-thaw state. Instrument and mission details are shown. The key SMAP soil moisture product is provided at 10 km resolution with 0.04cubic cm/cubic cm accuracy. The freeze/thaw product is provided at 3 km resolution and 80% frozen-thawed classification accuracy. The full list of SMAP data products is shown.

Solar microwave bursts - A review

NASA Technical Reports Server (NTRS)

Kundu, M. R.; Vlahos, L.

1982-01-01

Observational and theoretical results on the physics of microwave bursts that occur in the solar atmosphere are reviewed. Special attention is given to the advances made in burst physics over the last few years with the great improvement in spatial and time resolution, especially with instruments like the NRAO three-element interferometer, the Westerbork Synthesis Radio Telescope, and more recently the Very Large Array. Observations made on the preflare build-up of an active region at centimeter wavelengths are reviewed. Three distinct phases in the evolution of cm bursts, namely the impulsive phase, the post-burst phase, and the gradual rise and fall, are discussed. Attention is also given to the flux density spectra of centimeter bursts. Descriptions are given of observations of fine structures with temporal resolution of 10-100 ms in the intensity profiles of cm-wavelength bursts. High spatial resolution observations are analyzed, with special reference to the one- and two-dimensional maps of cm burst sources.

Absorption, autoionization, and predissociation in molecular hydrogen: High-resolution spectroscopy and multichannel quantum defect theory.

PubMed

Sommavilla, M; Merkt, F; Mezei, J Zs; Jungen, Ch

2016-02-28

Absorption and photoionization spectra of H2 have been recorded at a resolution of 0.09 and 0.04 cm(-1), respectively, between 125,600 cm(-1) and 126,000 cm(-1). The observed Rydberg states belong to series (n = 10 - 14) converging on the first vibrationally excited level of the X (2)Σ(g)(+) state of H2(+), and of lower members of series converging on higher vibrational levels. The observed resonances are characterized by the competition between autoionization, predissociation, and fluorescence. The unprecedented resolution of the present experimental data leads to a full characterization of the predissociation/autoionization profiles of many resonances that had not been resolved previously. Multichannel quantum defect theory is used to predict the line positions, widths, shapes, and intensities of the observed spectra and is found to yield quantitative agreement using previously determined quantum defect functions as the unique set of input parameters.

Direct nano-patterning of graphene with helium ion beams

NASA Astrophysics Data System (ADS)

Naitou, Y.; Iijima, T.; Ogawa, S.

2015-01-01

Helium ion microscopy (HIM) was used for direct nano-patterning of single-layer graphene (SLG) on SiO2/Si substrates. This technique involves irradiation of the sample with accelerated helium ions (He+). Doses of 2.0 × 1016 He+ cm-2 from a 30 kV beam induced a metal-insulator transition in the SLG. The resolution of HIM patterning on SLG was investigated by fabricating nanoribbons and nanostructures. Analysis of scanning capacitance microscopy measurements revealed that the spatial resolution of HIM patterning depended on the dosage of He+ in a non-monotonic fashion. Increasing the dose from 2.0 × 1016 to 5.0 × 1016 He+ cm-2 improved the spatial resolution to several tens of nanometers. However, doses greater than 1.0 × 1017 He+ cm-2 degraded the patterning characteristics. Direct patterning using HIM is a versatile approach to graphene fabrication and can be applied to graphene-based devices.

Confocal imaging of benign and malignant proliferative skin lesions in vivo

NASA Astrophysics Data System (ADS)

Gonzalez, Salvador; Rajadhyaksha, Milind M.; Anderson, R. Rox

1999-06-01

Near-infrared confocal reflectance microscopy (CM) provides non- invasive real-time images of thin en-face tissue sections with high resolution and contrast. Imaging of cells, nuclei, other organelles, microvessels, and hair follicles has been possible at resolution comparable to standard histology, to a maximum depth of 250-300 μm in human skin in vivo. We have characterized psoriasis as a prototype of benign proliferative skin conditions, and non-pigmented skin malignancies in vivo based on their unstained, native histologic features using CM. Our data shows that reflectance CM may potentially diagnose and morphometrically evaluate proliferative skin lesions in vivo.

A search for formic acid in the upper troposphere - A tentative identification of the 1105-per cm nu-6 band Q branch in high-resolution balloon-borne solar absorption spectra

NASA Technical Reports Server (NTRS)

Goldman, A.; Murcray, F. H.; Murcray, D. G.; Rinsland, C. P.

1984-01-01

Infrared solar absorption spectra recorded at 0.02-per cm resolution during a balloon flight from Alamogordo, NM (33 deg N), on March 23, 1981, have been analyzed for the possible presence of absorption by formic acid (HCOOH). An absorption feature at 1105 per cm has been tentatively identified in upper tropospheric spectra as due to the nu-6 band Q branch. A preliminary analysis indicates a concentration of about 0.6 ppbv and 0.4 ppbv near 8 and 10 km, respectively.

The structure of the Cepheus E protostellar outflow: The jet, the bowshock, and the cavity

NASA Astrophysics Data System (ADS)

Lefloch, B.; Gusdorf, A.; Codella, C.; Eislöffel, J.; Neri, R.; Gómez-Ruiz, A. I.; Güsten, R.; Leurini, S.; Risacher, C.; Benedettini, M.

2015-09-01

Context. Protostellar outflows are a crucial ingredient of the star-formation process. However, the physical conditions in the warm outflowing gas are still poorly known. Aims: We present a multi-transition, high spectral resolution CO study of the outflow of the intermediate-mass Class 0 protostar Cep E-mm. The goal is to determine the structure of the outflow and to constrain the physical conditions of the various components in order to understand the origin of the mass-loss phenomenon. Methods: We have observed the J = 12-11, J = 13-12, and J = 16-15 CO lines at high spectral resolution with SOFIA/GREAT and the J = 5-4, J = 9-8, and J = 14-13 CO lines with HIFI/Herschel towards the position of the terminal bowshock HH377 in the southern outflow lobe. These observations were complemented with maps of CO transitions obtained with the IRAM 30 m telescope (J = 1-0, 2-1), the Plateau de Bure interferometer (J = 2-1), and the James Clerk Maxwell Telescope (J = 3-2, 4-3). Results: We identify three main components in the protostellar outflow: the jet, the cavity, and the bowshock, with a typical size of 1.7″ × 21″, 4.5″, and 22″ × 10″, respectively. In the jet, the emission from the low-J CO lines is dominated by a gas layer at Tkin = 80-100 K, column density N(CO) = 9 × 1016 cm-2, and density n(H2) = (0.5-1) × 105 cm-3; the emission of the high-J CO lines arises from a warmer (Tkin = 400-750 K), denser (n(H2) = (0.5-1) × 106 cm-3), lower column density (N(CO) = 1.5 × 1016 cm-2) gas component. Similarly, in the outflow cavity, two components are detected: the emission of the low-J lines is dominated by a gas layer of column density N(CO) = 7 × 1017 cm-2 at Tkin = 55-85 K and density in the range (1-8) × 105 cm-3; the emission of the high-J lines is dominated by a hot, denser gas layer with Tkin = 500-1500K, n(H2) = (1-5) × 106 cm-3, and N(CO) = 6 × 1016 cm-2. A temperature gradient as a function of the velocity is found in the high-excitation gas component. In the terminal bowshock HH377, we detect gas of moderate excitation, with a temperature in the range Tkin ≈ 400-500 K, density n(H2) ≃ (1 -2) × 106 cm-3 and column density N(CO) = 1017 cm-2. The amounts of momentum carried away in the jet and in the entrained ambient medium are similar. Comparison with time-dependent shock models shows that the hot gas emission in the jet is well accounted for by a magnetized shock with an age of 220-740 yr propagating at 20-30 km s-1 in a medium of density n(H2) = (0.5-1) × 105 cm-3, consistent with that of the bulk material. Conclusions: The Cep E protostellar outflow appears to be a convincing case of jet bowshock driven outflow. Our observations trace the recent impact of the protostellar jet into the ambient cloud, produing a non-stationary magnetized shock, which drives the formation of an outflow cavity. Appendices are available in electronic form at http://www.aanda.org

Photodissociation resonances of jet-cooled NO2 at the dissociation threshold by CW-CRDS

NASA Astrophysics Data System (ADS)

Dupré, Patrick

2015-05-01

Around 398 nm, the jet-cooled-spectrum of NO2 exhibits a well identified dissociation threshold (D0). Combining the continuous-wave absorption-based cavity ringdown spectroscopy technique and laser induced fluorescence detection, an energy range of ˜25 cm-1 is analyzed at high resolution around D0. In addition to the usual molecular transitions to long-lived energy levels, ˜115 wider resonances are observed. The position, amplitude, and width of these resonances are determined. The resonance width spreads from ˜0.006 cm-1 (i.e., ˜450 ps) to ˜0.7 cm-1 (˜4 ps) with large fluctuations. The identification of at least two ranges of resonance width versus the excess energy can be associated with the opening of the dissociation channels NO 2 → NO (X 2 Π 1 / 2 , v = 0 , J = 1 / 2) + O (3 P 2) and NO 2 → NO (X 2 Π 1 / 2 , v = 0 , J = 3 / 2) + O (3 P 2). This analysis corroborates the existence of loose transition states close to the dissociation threshold as reported previously and in agreement with the phase space theory predictions as shown by Tsuchiya's group [Miyawaki et al., J. Chem. Phys. 99, 254-264 (1993)]. The data are analyzed in the light of previously reported frequency- and time-resolved data to provide a robust determination of averaged unimolecular dissociation rate coefficients. The density of reactant levels deduced (ρreac ˜ 11 levels/cm-1) is discussed versus the density of transitions, the density of resonances, and the density of vibronic levels.

High-Resolution Monitoring of Soil Water Dynamics in a Vegetated Hillslope by Active Distributed Temperature Sensing

NASA Astrophysics Data System (ADS)

Ciocca, F.; Krause, S.; Blaen, P.; Hannah, D. M.; Chalari, A.; Mondanos, M.; Abesser, C.

2016-12-01

Water and thermal conditions in the shallow vadose zone can be very complex and dynamic across a range of spatiotemporal scales. The efficient analysis of such dynamics requires technologies capable of precise and high-resolution monitoring of soil temperature and moisture across multiple scales. Optical fibre distributed temperature sensors (DTS) allows for precise temperature measurements at high spatio-temporal resolution, over several kilometres of optical fibre cable. In addition to passive temperature monitoring, hybrid optical cables with embedded metal conductors can be electrically heated and allow for distributed heat pulses. Such Active-DTS technique involves the analysis of temperatures during both heating and cooling phases of an optical fibre cable buried in the soil in order to provide distributed soil moisture estimates. In summer 2015, three loops of a 500m hybrid-optical cable have been deployed at 10cm, 25cm and 40cm depths along a hillslope with juvenile forest. Active-DTS surveys have been conducted with the aim to: (i) monitor the post-installation soil settling around the cable; (ii) analyse different heating strategies (intensity, duration) of the cable; (iii) establish a method for inferring soil moisture from Active-DTS results and validate with independent soil moisture readings from point probes; (iv) monitor the soil moisture response to short forcing events such as storms and artificial irrigation. Results from the surveys will be presented, and first assumptions on how the obtained soil water dynamics can be associated to specific triggers such as precipitation, evapotranspiration, soil inclination, will be discussed. This research is part of the British National Environmental Research Council (NERC) funded Distributed intelligent Heat Pulse System (DiHPS) project and is realised in the context of the Free Air Carbon Enrichment (FACE) experiment, in collaboration with the Birmingham Institute of Forest Research (BIFoR).

Effect of internal stress on the electro-optical behaviour of Al-doped ZnO transparent conductive thin films

NASA Astrophysics Data System (ADS)

Proost, J.; Henry, F.; Tuyaerts, R.; Michotte, S.

2016-08-01

In this work, we will report on scientific efforts aimed at unraveling the quantitative effect of elastic strain on the electro-optical behaviour of Al-doped zinc oxide (AZO). AZO thin films have been deposited by reactive magnetron sputtering to thicknesses from 300 to 500 nm, both on extra-clear glass substrates as well as on oxidised Si wafers. This resulted in both cases in polycrystalline, strongly textured (002) films. During deposition, the internal stress evolution in the growing film was monitored in-situ using high resolution curvature measurements. The resulting growth-induced elastic strain, which was found to depend heavily on the oxygen partial pressure, could further be modulated by appropriately choosing the deposition temperature. The latter also induces an additional extrinsic thermal stress component, whose sign depends on the substrate used. As such, a wide range of biaxial internal stresses could be achieved, from -600 MPa in compression up to 800 MPa in tension. The resulting charge carrier mobilities, obtained independently from room temperature Hall measurements, were found to range between 5 and 25 cm2/V s. Interestingly, the maximum mobility occurred at the zero-stress condition, and together with a charge carrier concentration of about 8 × 1020 cm-3, this gave rise to a resistivity of only 300 μΩ cm. From the stress-dependent optical transmission spectra in the range of 200-1000 nm, the pressure coefficient of the optical bandgap was estimated from the corresponding Tauc plots to be 31 meV/GPa, indicating a very high strain-sensitivity as well.

Self-assembly of magnetic nanoclusters in diamond-like carbon by diffusion processes enhanced by collision cascades

NASA Astrophysics Data System (ADS)

Gupta, P.; Williams, G. V. M.; Hübner, R.; Vajandar, S.; Osipowicz, T.; Heinig, K.-H.; Becker, H.-W.; Markwitz, A.

2017-04-01

Mono-energetic cobalt implantation into hydrogenated diamond-like carbon at room temperature results in a bimodal distribution of implanted atoms without any thermal treatment. The ˜100 nm thin films were synthesised by mass selective ion beam deposition. The films were implanted with cobalt at an energy of 30 keV and an ion current density of ˜5 μA cm-2. Simulations suggest the implantation profile to be single Gaussian with a projected range of ˜37 nm. High resolution Rutherford backscattering measurements reveal that a bimodal distribution evolves from a single near-Gaussian distribution as the fluence increases from 1.2 to 7 × 1016 cm-2. Cross-sectional transmission electron microscopy further reveals that the implanted atoms cluster into nanoparticles. At high implantation doses, the nanoparticles assemble primarily in two bands: one near the surface with nanoparticle diameters of up to 5 nm and the other beyond the projected range with ˜2 nm nanoparticles. The bimodal distribution along with the nanoparticle formation is explained with diffusion enhanced by energy deposited during collision cascades, relaxation of thermal spikes, and defects formed during ion implantation. This unique distribution of magnetic nanoparticles with the bimodal size and range is of significant interest to magnetic semiconductor and sensor applications.

Study of soil aggregate breakdown dynamics under low dispersive ultrasonic energies with sedimentation and X-ray attenuation

NASA Astrophysics Data System (ADS)

Schomakers, Jasmin; Zehetner, Franz; Mentler, Axel; Ottner, Franz; Mayer, Herwig

2015-10-01

It has been increasingly recognized that soil organic matter stabilization is strongly controlled by physical binding within soil aggregates. It is therefore essential to measure soil aggregate stability reliably over a wide range of disruptive energies and different aggregate sizes. To this end, we tested highaccuracy ultrasonic dispersion in combination with subsequent sedimentation and X-ray attenuation. Three arable topsoils (notillage) from Central Europe were subjected to ultrasound at four different specific energy levels: 0.5, 6.7, 100 and 500 J cm-3, and the resulting suspensions were analyzed for aggregate size distribution by wet sieving (2 000-63 μm) and sedimentation/X-ray attenuation (63-2 μm). The combination of wet sieving and sedimentation technique allowed for a continuous analysis, at high resolution, of soil aggregate breakdown dynamics after defined energy inputs. Our results show that aggregate size distribution strongly varied with sonication energy input and soil type. The strongest effects were observed in the range of low specific energies (< 10 J cm-3), which previous studies have largely neglected. This shows that low ultrasonic energies are required to capture the full range of aggregate stability and release of soil organic matter upon aggregate breakdown.

Multi-chord fiber-coupled interferometer with a long coherence length laser

NASA Astrophysics Data System (ADS)

Merritt, Elizabeth C.; Lynn, Alan G.; Gilmore, Mark A.; Hsu, Scott C.

2012-03-01

This paper describes a 561 nm laser heterodyne interferometer that provides time-resolved measurements of line-integrated plasma electron density within the range of 1015-1018 cm-2. Such plasmas are produced by railguns on the plasma liner experiment, which aims to produce μs-, cm-, and Mbar-scale plasmas through the merging of 30 plasma jets in a spherically convergent geometry. A long coherence length, 320 mW laser allows for a strong, sub-fringe phase-shift signal without the need for closely matched probe and reference path lengths. Thus, only one reference path is required for all eight probe paths, and an individual probe chord can be altered without altering the reference or other probe path lengths. Fiber-optic decoupling of the probe chord optics on the vacuum chamber from the rest of the system allows the probe paths to be easily altered to focus on different spatial regions of the plasma. We demonstrate that sub-fringe resolution capability allows the interferometer to operate down to line-integrated densities of the order of 5 × 1015 cm-2.

Resolution of Tachyarrhythmia Following Posterior Fossa Decompression Surgery for Chiari Malformation Type I.

PubMed

Elia, Christopher; Brazdzionis, James; Tashjian, Vartan

2018-03-01

Chiari malformation (CM) type I commonly presents with symptoms such as tussive headaches, paresthesias, and, in severe cases, corticobulbar dysfunction. However, patients may present with atypical symptoms lending to the complexity in this patient population. We present a case of a CM patient presenting with atypical cardiac symptoms and arrhythmias, all of which resolved after surgical decompression. A 31-year-old female presented with atypical chest pain, palpitations, tachycardia, headaches, and dizziness for 2 years. Multiple antiarrhythmics and ultimately cardiac ablation procedure proved to be ineffective. Magnetic resonance imaging revealed CM, and the patient ultimately underwent surgical decompression with subsequent resolution of her symptoms. The surgical management of CM patients presenting with atypical symptoms can be challenging and often lead to delays in intervention. To our knowledge this is the only reported case of a patient presenting with tachyarrhythmia and atypical chest pain with resolution after Chiari decompression. We believe the dramatic improvement documented in the present case should serve to advance Chiari decompression in CM patients presenting with refractory tachyarrhythmia in whom no other discernable cause has been elucidated. Further studies are needed to better correlate the findings and to hopefully establish a criteria for patients that will likely benefit from surgical decompression. Copyright © 2017 Elsevier Inc. All rights reserved.

Single Photon Counting Large Format Imaging Sensors with High Spatial and Temporal Resolution

NASA Astrophysics Data System (ADS)

Siegmund, O. H. W.; Ertley, C.; Vallerga, J. V.; Cremer, T.; Craven, C. A.; Lyashenko, A.; Minot, M. J.

High time resolution astronomical and remote sensing applications have been addressed with microchannel plate based imaging, photon time tagging detector sealed tube schemes. These are being realized with the advent of cross strip readout techniques with high performance encoding electronics and atomic layer deposited (ALD) microchannel plate technologies. Sealed tube devices up to 20 cm square have now been successfully implemented with sub nanosecond timing and imaging. The objective is to provide sensors with large areas (25 cm2 to 400 cm2) with spatial resolutions of <20 μm FWHM and timing resolutions of <100 ps for dynamic imaging. New high efficiency photocathodes for the visible regime are discussed, which also allow response down below 150nm for UV sensing. Borosilicate MCPs are providing high performance, and when processed with ALD techniques are providing order of magnitude lifetime improvements and enhanced photocathode stability. New developments include UV/visible photocathodes, ALD MCPs, and high resolution cross strip anodes for 100 mm detectors. Tests with 50 mm format cross strip readouts suitable for Planacon devices show spatial resolutions better than 20 μm FWHM, with good image linearity while using low gain ( 106). Current cross strip encoding electronics can accommodate event rates of >5 MHz and event timing accuracy of 100 ps. High-performance ASIC versions of these electronics are in development with better event rate, power and mass suitable for spaceflight instruments.

Design and Performance of a 1 mm3 Resolution Clinical PET System Comprising 3-D Position Sensitive Scintillation Detectors.

PubMed

Hsu, David F C; Freese, David L; Reynolds, Paul D; Innes, Derek R; Levin, Craig S

2018-04-01

We are developing a 1-mm 3 resolution, high-sensitivity positron emission tomography (PET) system for loco-regional cancer imaging. The completed system will comprise two cm detector panels and contain 4 608 position sensitive avalanche photodiodes (PSAPDs) coupled to arrays of mm 3 LYSO crystal elements for a total of 294 912 crystal elements. For the first time, this paper summarizes the design and reports the performance of a significant portion of the final clinical PET system, comprising 1 536 PSAPDs, 98 304 crystal elements, and an active field-of-view (FOV) of cm. The sub-system performance parameters, such as energy, time, and spatial resolutions are predictive of the performance of the final system due to the modular design. Analysis of the multiplexed crystal flood histograms shows 84% of the crystal elements have>99% crystal identification accuracy. The 511 keV photopeak energy resolution was 11.34±0.06% full-width half maximum (FWHM), and coincidence timing resolution was 13.92 ± 0.01 ns FWHM at 511 keV. The spatial resolution was measured using maximum likelihood expectation maximization reconstruction of a grid of point sources suspended in warm background. The averaged resolution over the central 6 cm of the FOV is 1.01 ± 0.13 mm in the X-direction, 1.84 ± 0.20 mm in the Y-direction, and 0.84 ± 0.11 mm in the Z-direction. Quantitative analysis of acquired micro-Derenzo phantom images shows better than 1.2 mm resolution at the center of the FOV, with subsequent resolution degradation in the y-direction toward the edge of the FOV caused by limited angle tomography effects.

Optimizing the Timing Resolution for the NEXT Array

NASA Astrophysics Data System (ADS)

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

2016-09-01

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

The effect of resolution on viscous dissipation measured with 4D flow MRI in patients with Fontan circulation: Evaluation using computational fluid dynamics

PubMed Central

Cibis, Merih; Jarvis, Kelly; Markl, Michael; Rose, Michael; Rigsby, Cynthia; Barker, Alex J.; Wentzel, Jolanda J.

2016-01-01

Viscous dissipation inside Fontan circulation, a parameter associated with the exercise intolerance of Fontan patients, can be derived from computational fluid dynamics (CFD) or 4D flow MRI velocities. However, the impact of spatial resolution and measurement noise on the estimation of viscous dissipation is unclear. Our aim was to evaluate the influence of these parameters on viscous dissipation calculation. Six Fontan patients underwent whole heart 4D flow MRI. Subject-specific CFD simulations were performed. The CFD velocities were down-sampled to isotropic spatial resolutions of 0.5 mm, 1 mm, 2 mm and to MRI resolution. Viscous dissipation was compared between (1) high resolution CFD velocities, (2) CFD velocities down-sampled to MRI resolution, (3) down-sampled CFD velocities with MRI mimicked noise levels, and (4) in-vivo 4D flow MRI velocities. Relative viscous dissipation between subjects was also calculated. 4D flow MRI velocities (15.6±3.8 cm/s) were higher, although not significantly different than CFD velocities (13.8±4.7 cm/s, p=0.16), down-sampled CFD velocities (12.3±4.4 cm/s, p=0.06) and the down-sampled CFD velocities with noise (13.2±4.2 cm/s, p=0.06). CFD-based viscous dissipation (0.81±0.55 mW) was significantly higher than those based on down-sampled CFD (0.25±0.19 mW, p=0.03), down-sampled CFD with noise (0.49±0.26 mW, p=0.03) and 4D flow MRI (0.56±0.28 mW, p=0.06). Nevertheless, relative viscous dissipation between different subjects was maintained irrespective of resolution and noise, suggesting that comparison of viscous dissipation between patients is still possible. PMID:26298492

High resolution mapping of soil organic carbon stocks using remote sensing variables in the semi-arid rangelands of eastern Australia.

PubMed

Wang, Bin; Waters, Cathy; Orgill, Susan; Gray, Jonathan; Cowie, Annette; Clark, Anthony; Liu, De Li

2018-07-15

Efficient and effective modelling methods to assess soil organic carbon (SOC) stock are central in understanding the global carbon cycle and informing related land management decisions. However, mapping SOC stocks in semi-arid rangelands is challenging due to the lack of data and poor spatial coverage. The use of remote sensing data to provide an indirect measurement of SOC to inform digital soil mapping has the potential to provide more reliable and cost-effective estimates of SOC compared with field-based, direct measurement. Despite this potential, the role of remote sensing data in improving the knowledge of soil information in semi-arid rangelands has not been fully explored. This study firstly investigated the use of high spatial resolution satellite data (seasonal fractional cover data; SFC) together with elevation, lithology, climatic data and observed soil data to map the spatial distribution of SOC at two soil depths (0-5cm and 0-30cm) in semi-arid rangelands of eastern Australia. Overall, model performance statistics showed that random forest (RF) and boosted regression trees (BRT) models performed better than support vector machine (SVM). The models obtained moderate results with R 2 of 0.32 for SOC stock at 0-5cm and 0.44 at 0-30cm, RMSE of 3.51MgCha -1 at 0-5cm and 9.16MgCha -1 at 0-30cm without considering SFC covariates. In contrast, by including SFC, the model accuracy for predicting SOC stock improved by 7.4-12.7% at 0-5cm, and by 2.8-5.9% at 0-30cm, highlighting the importance of including SFC to enhance the performance of the three modelling techniques. Furthermore, our models produced a more accurate and higher resolution digital SOC stock map compared with other available mapping products for the region. The data and high-resolution maps from this study can be used for future soil carbon assessment and monitoring. Copyright © 2018 Elsevier B.V. All rights reserved.

Impulse response measurement in the HgCdTe avalanche photodiode

NASA Astrophysics Data System (ADS)

Singh, Anand; Pal, Ravinder

2018-04-01

HgCdTe based mid-wave infrared focal plane arrays (MWIR FPAs) are being developed for high resolution imaging and range determination of distant camouflaged targets. Effect of bandgap grading on the response time in the n+/ν/p+ HgCdTe electron avalanche photodiode (e-APD) is evaluated using impulse response measurement. Gain normalized dark current density of 2 × 10-9 A/cm2 at low reverse bias for passive mode and 2 × 10-4 A/cm2 at -8 V for active mode is measured in the fabricated APD device, yielding high gain bandwidth product of 2.4 THZ at the maximum gain. Diffusion of carriers is minimized to achieve transit time limited impulse response by introducing composition grading in the HgCdTe epilayer. The noise equivalent photon performance less than one is achievable in the FPA that is suitable for active cum passive imaging applications.

Design and fabrication of engineering model fiber-optics detector

NASA Technical Reports Server (NTRS)

Mcsweeney, A.

1972-01-01

The design and fabrication of an annular ring detector consisting of optical fibers terminated with photodetectors is described. The maximum width of each concentric ring has to be small enough to permit the resolution of a Ronchi ruling transform with a dot spacing of 150 microns. A minimum of 100 concentric rings covering a circular area of 2.54 cm diameter also is necessary. A fiber-optic array consisting of approximately 89,000 fibers of 76 microns diameter was fabricated to meet the above requirements. The fibers within a circular area of 2.5 cm diameter were sorted into 168 adjacent rings concentric with the center fiber. The response characteristics of several photodetectors were measured, and the data used to compare their linearity of response and dynamic range. Also, coupling loss measurements were made for three different methods of terminating the optical fibers with a photodetector.

Yb fiber laser pumped mid-IR source based on difference frequency generation and its application to ammonia detection

NASA Technical Reports Server (NTRS)

Matsuoka, N.; Yamaguchi, S.; Nanri, K.; Fujioka, T.; Richter, D.; Tittel, F. K.

2001-01-01

A Yb fiber laser pumped cw narrow-linewidth tunable mid-IR source based on a difference frequency generation (DFG) in a periodically poled LiNbO3 (PPLN) crystal for trace gas detection was demonstrated. A high power Yb fiber laser and a distributed feedback (DFB) laser diode were used as DFG pump sources. This source generated mid-IR at 3 microns with a powers of 2.5 microW and a spectral linewidth of less than 30 MHz. A frequency tuning range of 300 GHz (10 cm-1) was obtained by varying the current and temperature of the DFB laser diode. A high-resolution NH3 absorption Doppler-broadened spectrum at 3295.4 cm-1 (3.0345 microns) was obtained at a cell pressure of 27 Pa from which a detection sensitivity of 24 ppm m was estimated.

Extreme Ultraviolet Emission Spectrum of CO_2 Induced by Electron Impact at 200 eV

NASA Technical Reports Server (NTRS)

Kanik, I.; Ajello, J. M.; James, G. K.

1993-01-01

We present the extreme ultraviolet (EUV) emission spectrum of CO_2 induced by electronimpact at 200 eV. There are 36 spectral features which are identified with a resolution of 0.5 nmover the wavelength range of 40 to 125 nm. Absolute emission cross sections were obtained for eachof these features. The EUV emission spectrum induced by electron impact consist of atomicmultiplets of CI,II and OI,II,III as well as CO and CO^+ molecular band systems produced bydissociative excitation. The CI (119.4 nm) multiplet is the strongest feature of CI with a peak crosssection of 3.61 x 10^(-19) cm^2 at 200 eV. The strongest feature of OI in the EUV spectrum is theOI (99.0 nm) multiplet with a peak cross section of 3.59 x 10^(-19) cm^2 at 200 eV.

On the relation between spectral characteristics of the microwave emission from solar active regions and physical conditions of the solar atmosphere.

NASA Astrophysics Data System (ADS)

Kaverin, N. S.; Kobrin, M. M.; Korshunov, A. I.; Shushunov, V. V.; Aurass, H.; Fürstenberg, F.; Hildebrandt, J.; Krüger, A.; Seehafer, N.

Spectrographic observations of the microwave emission from selected active regions were analysed and compared with S-component emission models. The observations were obtained by spectrographs of the NIRFI working in the ranges 12 - 8 and 7 - 5 GHz covering the high-frequency part of the S-component spectrum. The measurements were carried out at the RT-22 radio telescope of the FIAN Radio Astronomy Station at Pushtshino with an angular resolution of about 9 arc minutes. The conclusions obtained mainly relate to the reversal of the slope of the flux spectrum in the short cm-region by the change of the emission mechanism, to an excess of the observed flux spectrum at long cm-waves and to the interpretation of the proton-flare criterion of Tanaka and Kakinuma on the basis of model calculations.

Cis- and trans-perfluorodecalin: Infrared spectra, radiative efficiency and global warming potential

NASA Astrophysics Data System (ADS)

Le Bris, Karine; DeZeeuw, Jasmine; Godin, Paul J.; Strong, Kimberly

2017-12-01

Perfluorodecalin (PFD) is a molecule used in various medical applications for its capacity to dissolve gases. This potent greenhouse gas was detected for the first time in the atmosphere in 2005. We present infrared absorption cross-section spectra of a pure vapour of cis- and trans-perfluorodecalin at a resolution of 0.1 cm-1. Measurements were performed in the 560-3000 cm-1 spectral range using Fourier transform spectroscopy. The spectra have been compared with previous experimental data and theoretical calculations by density functional theory. The new experimental absorption cross-sections have been used to calculate a lifetime-corrected radiative efficiency at 300 K of 0.62 W m-2 ppb-1 and 0.57 W.m-2.ppb-1 for the cis and trans isomers respectively. This leads to a 100-year time horizon global warming potential of 8030 for cis-PFD and 7440 for trans-PFD.

Chaos Through-Wall Imaging Radar

NASA Astrophysics Data System (ADS)

Xu, Hang; Wang, Bingjie; Zhang, Jianguo; Liu, Li; Li, Ying; Wang, Yuncai; Wang, Anbang

2017-12-01

We experimentally demonstrate a chaos through-wall imaging radar using ultra-wideband chaotic-pulse-position modulation (CPPM) microwave signal. The CPPM signal based on logistic map with 1-ns pulse width and 1-GHz bandwidth is implemented by a field programmable gate array (FPGA) and then up-converted as the radar transmitting signal. Two-dimensional image of human objects behind obstacles is obtained by correlation method and back projection algorithm. Our experiments successfully perform through-wall imaging for single and multiple human objects through 20-cm thick wall. The down-range resolution of the proposed radar is 15 cm. Furthermore, the anti-jamming properties of the proposed radar in CPPM jamming, linear frequency-modulated jamming, and Gaussian noise jamming environments are demonstrated by electromagnetic simulations using the finite-difference time-domain. The simulation results show the CPPM microwave signal possesses excellent jamming immunity to the noise and radio frequency interference, which makes it perform superbly in multiradar environments.

Development of a 3D printer using scanning projection stereolithography

PubMed Central

Lee, Michael P.; Cooper, Geoffrey J. T.; Hinkley, Trevor; Gibson, Graham M.; Padgett, Miles J.; Cronin, Leroy

2015-01-01

We have developed a system for the rapid fabrication of low cost 3D devices and systems in the laboratory with micro-scale features yet cm-scale objects. Our system is inspired by maskless lithography, where a digital micromirror device (DMD) is used to project patterns with resolution up to 10 µm onto a layer of photoresist. Large area objects can be fabricated by stitching projected images over a 5cm2 area. The addition of a z-stage allows multiple layers to be stacked to create 3D objects, removing the need for any developing or etching steps but at the same time leading to true 3D devices which are robust, configurable and scalable. We demonstrate the applications of the system by printing a range of micro-scale objects as well as a fully functioning microfluidic droplet device and test its integrity by pumping dye through the channels. PMID:25906401

Upper limits to the interstellar radiation field between 775 and 1050 A

NASA Technical Reports Server (NTRS)

Paresce, F.; Bowyer, S.

1976-01-01

A 40-A resolution extreme-ultraviolet spectrometer, sensitive to radiation in the 775-1050 A band, was flown on a Black Brant VC rocket to measure the night sky brightness in this region of the electromagnetic spectrum. A weak signal above background was recorded in most channels as the spectrometer's field of view scanned the sky in the vicinity of the galactic plane from Monoceros to Andromeda. Because the earth's upper atmosphere may produce some radiation in this wavelength region, the possibility cannot be excluded that some or all of the observed signal is terrestrial in origin. However, observational upper limits can be established at the 95-per cent confidence level for the intensity of an extraterrestrial extreme ultraviolet background which ranges from 6 millionths erg/sq cm/s/sr/A at 1050 A to 4 ten-millionths erg/sq cm/s/sr/A at 775 A. These results are consistent with existing theoretical predictions.

Two-crystal mid-infrared optical parametric oscillator for absorption and dispersion dual-comb spectroscopy.

PubMed

Jin, Yuwei; Cristescu, Simona M; Harren, Frans J M; Mandon, Julien

2014-06-01

We present a femtosecond optical parametric oscillator (OPO) containing two magnesium-doped periodically poled lithium niobate crystals in a singly resonant ring cavity, pumped by two mode-locked Yb-fiber lasers. As such, the OPO generates two idler combs (up to 220 mW), covering a wavelength range from 2.7 to 4.2 μm, from which a mid-infrared dual-comb Fourier transform spectrometer is constructed. By detecting the heterodyning signal between the two idler beams a full broadband spectrum of a molecular gas can be observed over 250  cm(-1) within 70 μs with a spectral resolution of 15 GHz. The absorption and dispersion spectra of acetylene and methane have been measured around 3000  cm(-1), indicating that this OPO represents an ideal broadband mid-infrared source for fast chemical sensing.

Design of an FT-NIR spectrometer for online quality analysis of traditional Chinese medicine manufacturing process

NASA Astrophysics Data System (ADS)

Zhu, Ren; Wu, Lan; Wang, Shiming; Ye, Linhua; Ding, Zhihua

2008-03-01

As a fast, non-destructive analysis method, Fourier transform (FT) near-infrared (NIR) spectroscopy is very suitable and effective for online quality analysis of traditional Chinese medicine (TCM) manufacturing process. In this thesis, the theoretics of FT-NIRS was analyzed and an FT-NIR spectrometer with 4 cm -1 resolution in the 12500-5000 cm -1 frequency range was designed. The spectrometer was based on a Michelson interferometer with Bromine tungsten lamp as the NIR light source and InGaAs detector to collect the interference signal. Each element was designed and chosen to provide maximum sensitivity in the NIR spectral region. A fiber-optic flow cell system was used to realize online analysis of traditional Chinese medicine. The performance of the spectrometer was evaluated and the feasibility of using FT-NIR spectrometer to get absorption spectra of traditional Chinese medicine was demonstrated.

Airborne Lidar measurements of the atmospheric pressure profile with tunable Alexandrite lasers

NASA Technical Reports Server (NTRS)

Korb, C. L.; Schwemmer, G. K.; Dombrowski, M.; Milrod, J.; Walden, H.

1986-01-01

The first remote measurements of the atmospheric pressure profile made from an airborne platform are described. The measurements utilize a differential absorption lidar and tunable solid state Alexandrite lasers. The pressure measurement technique uses a high resolution oxygen A band where the absorption is highly pressure sensitive due to collision broadening. Absorption troughs and regions of minimum absorption were used between pairs of stongly absorption lines for these measurements. The trough technique allows the measurement to be greatly desensitized to the effects of laser frequency instabilities. The lidar system was set up to measure pressure with the on-line laser tuned to the absorption trough at 13147.3/cm and with the reference laser tuned to a nonabsorbing frequency near 13170.0/cm. The lidar signal returns were sampled with a 200 range gate (30 vertical resoltion) and averaged over 100 shots.

High resolution coherence domain depth-resolved nailfold capillaroscopy based on correlation mapping optical coherence tomography

NASA Astrophysics Data System (ADS)

Subhash, Hrebesh M.; O'Gorman, Sean; Neuhaus, Kai; Leahy, Martin

2014-03-01

In this paper we demonstrate a novel application of correlation mapping optical coherence tomography (cm-OCT) for volumetric nailfold capillaroscopy (NFC). NFC is a widely used non-invasive diagnostic method to analyze capillary morphology and microvascular abnormalities of nailfold area for a range of disease conditions. However, the conventional NFC is incapable of providing volumetric imaging, when volumetric quantitative microangiopathic parameters such as plexus morphology, capillary density, and morphologic anomalies of the end row loops most critical. cm-OCT is a recently developed well established coherence domain magnitude based angiographic modality, which takes advantage of the time-varying speckle effect, which is normally dominant in the vicinity of vascular regions compared to static tissue region. It utilizes the correlation coefficient as a direct measurement of decorrelation between two adjacent B-frames to enhance the visibility of depth-resolved microcirculation.

Fast discrimination of hydroxypropyl methyl cellulose using portable Raman spectrometer and multivariate methods

NASA Astrophysics Data System (ADS)

Song, Biao; Lu, Dan; Peng, Ming; Li, Xia; Zou, Ye; Huang, Meizhen; Lu, Feng

2017-02-01

Raman spectroscopy is developed as a fast and non-destructive method for the discrimination and classification of hydroxypropyl methyl cellulose (HPMC) samples. 44 E series and 41 K series of HPMC samples are measured by a self-developed portable Raman spectrometer (Hx-Raman) which is excited by a 785 nm diode laser and the spectrum range is 200-2700 cm-1 with a resolution (FWHM) of 6 cm-1. Multivariate analysis is applied for discrimination of E series from K series. By methods of principal components analysis (PCA) and Fisher discriminant analysis (FDA), a discrimination result with sensitivity of 90.91% and specificity of 95.12% is achieved. The corresponding receiver operating characteristic (ROC) is 0.99, indicting the accuracy of the predictive model. This result demonstrates the prospect of portable Raman spectrometer for rapid, non-destructive classification and discrimination of E series and K series samples of HPMC.

Feasibility study for Japanese Air Quality Mission from Geostationary Satellite: Infrared Imaging Spectrometer

NASA Astrophysics Data System (ADS)

Sagi, K.; Kasai, Y.; Philippe, B.; Suzuki, K.; Kita, K.; Hayashida, S.; Imasu, R.; Akimoto, H.

2009-12-01

A Geostationary Earth Orbit (GEO) satellite is potentially able to monitor the regional distribution of pollution with good spatial and temporal resolution. The Japan Society of Atmospheric Chemistry (JSAC) and the Japanese Space Exploration Agency (JAXA) initiated a concept study for air quality measurements from a GEO satellite targeting the Asian region [1]. This work presents the results of sensitivity studies for a Thermal Infrared (TIR) (650-2300cm-1) candidate instrument. We performed a simulation study and error analysis to optimize the instrumental operating frequencies and spectral resolution. The scientific requirements, in terms of minimum precision (or error) values, are 10% for tropospheric O3 and CO and total column of HN3 and nighttime HNO2 and 25% for O3 and CO with separating 2 or 3 column in troposphere. Two atmospheric scenarios, one is Asian background, second is polluted case, were assumed for this study. The forward calculations and the retrieval error analysis were performed with the AMATERASU model [2] developed within the NICT-THz remote sensing project. Retrieval error analysis employed the Optimal Estimation Method [3]. The geometry is off-nadir observation on Tokyo from the geostationary satellite at equator. Fine spectral resolution will allow to observe boundary layer O3 and CO. We estimate the observation precision in the spectral resolution from 0.1cm-1 to 1cm-1 for 0-2km, 2-6km, and 6-12km. A spectral resolution of 0.3 cm-1 gives good sensitivity for all target molecules (e.g. tropospheric O3 can be detected separated 2 column with error 30%). A resolution of 0.6 cm-1 is sufficient to detect tropospheric column amount of O3 and CO (in the Asian background scenario), which is within the required precision and with acceptable instrumental SNR values of 100 for O3 and 30 for CO. However, with this resolution, the boundary layer ozone will be difficult to detect in the background abundance. In addition, a spectral resolution of 0.6 cm-1 is sufficient to retrieve the total column of HNO3 and NO2 with a precision better than 10%. IR measurements will thus be useful for tropospheric pollution monitoring. Reference: [1] http://www.stelab.nagoya-u.ac.jp/ste-www1/div1/taikiken/eisei/eisei2.pdf, Japanese version only [2] P. Baron et al., AMATERASU: Model for Atmospheric TeraHertz Radiation Analysis and Simulation, Journal of the National Institute of Information and Communications Technology, 55(1), 109-121, 2008. [3] Rodgers. C. D., Inverse methods for atmospheric sounding: Theory and practice, World Scientific, Singapore (2000).

Sub-GHz-resolution C-band Nyquist-filtering interleaver on a high-index-contrast photonic integrated circuit.

PubMed

Zhuang, Leimeng; Zhu, Chen; Corcoran, Bill; Burla, Maurizio; Roeloffzen, Chris G H; Leinse, Arne; Schröder, Jochen; Lowery, Arthur J

2016-03-21

Modern optical communications rely on high-resolution, high-bandwidth filtering to maximize the data-carrying capacity of fiber-optic networks. Such filtering typically requires high-speed, power-hungry digital processes in the electrical domain. Passive optical filters currently provide high bandwidths with low power consumption, but at the expense of resolution. Here, we present a passive filter chip that functions as an optical Nyquist-filtering interleaver featuring sub-GHz resolution and a near-rectangular passband with 8% roll-off. This performance is highly promising for high-spectral-efficiency Nyquist wavelength division multiplexed (N-WDM) optical super-channels. The chip provides a simple two-ring-resonator-assisted Mach-Zehnder interferometer, which has a sub-cm² footprint owing to the high-index-contrast Si₃N₄/SiO₂ waveguide, while manifests low wavelength-dependency enabling C-band (> 4 THz) coverage with more than 160 effective free spectral ranges of 25 GHz. This device is anticipated to be a critical building block for spectrally-efficient, chip-scale transceivers and ROADMs for N-WDM super-channels in next-generation optical communication networks.

The ISOMAX Magnetic Rigidity Spectrometer

NASA Astrophysics Data System (ADS)

Hams, Thomas

1999-08-01

The Isotope Magnet Experiment, (ISOMAX), is a balloon-borne superconducting magnetic spectrometer with a time-of-flight system and aerogel Cherenkov counters. Its purpose is to measure the isotopic composition of the light elements (3 < Z < 8) in the cosmic radiation. Particle mass is derived from a velocity vs. magnetic rigidity (momentum/charge) technique. The experiment had its first flight in August 1998. The precision magnetic spectrometer uses advanced drift-chamber tracking and a large, high-field, superconducting magnet. The drift-chamber system consists of three chambers with 24 layers of hexagonal drift cells (16 bending, 8 non-bending) and a vertical extent of 1.4 m. Pure CO2 gas is used. The magnet is a split-pair design with 79 cm diameter coils and a separation of 80 cm. During the 1998 flight, the central field was 0.8 T (60% of the full design field). Presented are results from flight data, for a range of incident particle Z, on the spatial resolution and efficiency of the tracking system, and on the maximum detectable rigidity (MDR) of the spectrometer. For in-flight data, spatial resolutions of 54 mm for Z=2 and 45 mm for Z=4 are obtained. An MDR of 970 GV/c is achieved for Z=2.

Analysis of hydroquinone and some of its ethers by using capillary electrochromatography.

PubMed

Desiderio, C; Ossicini, L; Fanali, S

2000-07-28

Capillary electrochromatography (CEC) was used for the analysis of relevant compounds in cosmetic preparation. Hydroquinone (HQ) and some of its ethers (methyl-, dimethyl-, benzyl-, phenyl-, propyl-HQ derivatives) were analyzed by using an octadecylsilica (ODS) stationary phase packed in fused-silica capillary (100 microm I.D.; 30 cm and 21.5 cm total and effective lengths, respectively). 20 mM Ammonium acetate pH 6-acetonitrile (50-70%) were the mobile phases used for the experiments. The acetonitrile (ACN) content strongly influenced the resolution of the studied compounds as well as the efficiency and the retention factor. Baseline resolution for the studied analytes was achieved at both the lowest and the highest percentage of ACN, the last one providing the shortest analysis time. Mobile phase containing 70% of ACN was therefore used for the analysis of an extract of skin-toning cream declared to contain HQ. Good repeatability of both retention times, peak areas and peak areas ratio (Asample/Ainternational standard) was found. The calibration graphs were linear in the concentration range studied (5-90 microg/ml) with correlation coefficients between 0.9975 and 09991. The analysis of the cosmetic preparation revealed the presence of HQ (1.72%, w/w) and of two additional peaks (not identified).

Characterization and discrimination of large caliber gun blast and flash signatures

NASA Astrophysics Data System (ADS)

Steward, Bryan J.; Gross, Kevin C.; Perram, Glen P.

2012-06-01

Two hundred and one firings of three 152 mm howitzer munitions were observed to characterize firing signatures of a large caliber gun. Muzzle blast expansion was observed with high-speed (1600 Hz) optical imagery. The trajectory of the blast front was well approximated by a modified point-blast model described by constant rate of energy deposition. Visible and near-infrared (450 - 850 nm) spectra of secondary combustion were acquired at ~0.75 nm spectral resolution and depict strong contaminant emissions including Li, Na, K, Cu, and Ca. The O2 (X-->b) absorption band is evident in the blue wing of the potassium D lines and was used for monocular passive ranging accurate to within 4 - 9%. Timeresolved midwave infrared (1800 - 6000 cm-1) spectra were collected at 100 Hz and 32 cm-1 resolution. A low dimensional radiative transfer model was used to characterize plume emissions in terms of area, temperature, soot emissivity, and species concentrations. Combustion emissions have ~100 ms duration, 1200 - 1600 K temperature, and are dominated by H2O and CO2. Non-combusting plume emissions last ~20 ms, are 850 - 1050 K, and show significant continuum (emissivity ~0.36) and CO structure. Munitions were discriminated with 92 - 96% classification accuracy using only 1 - 3 firing signature features.

Intraluminal pressure patterns in the human colon assessed by high-resolution manometry

PubMed Central

Chen, Ji-Hong; Yu, Yuanjie; Yang, Zixian; Yu, Wen-Zhen; Chen, Wu Lan; Yu, Hui; Kim, Marie Jeong-Min; Huang, Min; Tan, Shiyun; Luo, Hesheng; Chen, Jianfeng; Chen, Jiande D. Z.; Huizinga, Jan D.

2017-01-01

Assessment of colonic motor dysfunction is rarely done because of inadequate methodology and lack of knowledge about normal motor patterns. Here we report on elucidation of intraluminal pressure patterns using High Resolution Colonic Manometry during a baseline period and in response to a meal, in 15 patients with constipation, chronically dependent on laxatives, 5 healthy volunteers and 9 patients with minor, transient, IBS-like symptoms but no sign of constipation. Simultaneous pressure waves (SPWs) were the most prominent propulsive motor pattern, associated with gas expulsion and anal sphincter relaxation, inferred to be associated with fast propagating contractions. Isolated pressure transients occurred in most sensors, ranging in amplitude from 5–230 mmHg. Rhythmic haustral boundary pressure transients occurred at sensors about 4–5 cm apart. Synchronized haustral pressure waves, covering 3–5 cm of the colon occurred to create a characteristic intrahaustral cyclic motor pattern at 3–6 cycles/min, propagating in mixed direction. This activity abruptly alternated with erratic patterns resembling the segmentation motor pattern of the small intestine. High amplitude propagating pressure waves (HAPWs) were too rare to contribute to function assessment in most subjects. Most patients, dependent on laxatives for defecation, were able to generate normal motor patterns in response to a meal. PMID:28216670

Characterization and discrimination of large caliber gun blast and flash signatures

NASA Astrophysics Data System (ADS)

Steward, Bryan J.

Two hundred and one firings of three 152 mm howitzer munitions were observed to characterize firing signatures of a large caliber gun. Muzzle blast expansion was observed with high-speed (1600 Hz) optical imagery. The trajectory of the blast front was well approximated by a modified point-blast model described by constant rate of energy deposition. Visible and near-infrared (450--850 nm) spectra of secondary combustion were acquired at ˜0.75 nm spectral resolution and depict strong contaminant emissions including Li, Na, K, Cu, and Ca. The O2 (X→b) absorption band is evident in the blue wing of the potassium D lines and was used for monocular passive ranging accurate to within 4--9%. Time-resolved midwave infrared (1800--6000 cm-1) spectra were collected at 100 Hz and 32 cm-1 resolution. A low dimensional radiative transfer model was used to characterize plume emissions in terms of area, temperature, soot emissivity, and species concentrations. Combustion emissions have ~100 ms duration, 1200--1600 K temperature, and are dominated by H2O and CO2. Non-combusting plume emissions last ~20 ms, are 850--1050 K, and show significant continuum (emissivity ˜0.36) and CO structure. Munitions were discriminated with 92--96% classification accuracy using only 1--3 firing signature features.

The VLA-COSMOS Survey - V. 324 MHz continuum observations

NASA Astrophysics Data System (ADS)

Smolčić, Vernesa; Ciliegi, Paolo; Jelić, Vibor; Bondi, Marco; Schinnerer, Eva; Carilli, Chris L.; Riechers, Dominik A.; Salvato, Mara; Brković, Alen; Capak, Peter; Ilbert, Olivier; Karim, Alexander; McCracken, Henry; Scoville, Nick Z.

2014-09-01

We present 90 cm Very Large Array imaging of the COSMOS field, comprising a circular area of 3.14 square degrees at 8.0arcsec × 6.0arcsec angular resolution with an average rms of 0.5 mJy beam-1. The extracted catalogue contains 182 sources (down to 5.5σ), 30 of which are multicomponent sources. Using Monte Carlo artificial source simulations, we derive the completeness of the catalogue, and we show that our 90 cm source counts agree very well with those from previous studies. Using X-ray, NUV-NIR and radio COSMOS data to investigate the population mix of our 90 cm radio sample, we find that our sample is dominated by active galactic nuclei. The average 90-20 cm spectral index (Sν ∝ να, where Sν is the flux density at frequency ν and α the spectral index) of our 90 cm selected sources is -0.70, with an interquartile range from -0.90 to -0.53. Only a few ultra-steep-spectrum sources are present in our sample, consistent with results in the literature for similar fields. Our data do not show clear steepening of the spectral index with redshift. Nevertheless, our sample suggests that sources with spectral indices steeper than -1 all lie at z ≳ 1, in agreement with the idea that ultra-steep-spectrum radio sources may trace intermediate-redshift galaxies (z ≳ 1).

Water absorption lines, 931-961 nm - Selected intensities, N2-collision-broadening coefficients, self-broadening coefficients, and pressure shifts in air

NASA Technical Reports Server (NTRS)

Giver, L. P.; Gentry, B.; Schwemmer, G.; Wilkerson, T. D.

1982-01-01

Intensities were measured for 97 lines of H2O vapor between 932 and 961 nm. The lines were selected for their potential usefulness for remote laser measurements of H2O vapor in the earth's atmosphere. The spectra were obtained with several different H2O vapor abundances and N2 broadening gas pressures; the spectral resolution was 0.046/cm FWHM. Measured H2O line intensities range from 7 x 10 to the -25th to 7 x 10 to the -22nd/cm per (molecules/sq cm). H2O self-broadening coefficients were measured for 13 of these strongest lines; the mean value was 0.5/cm per atm. N2-collision-broadening coefficients were measured for 73 lines, and the average was 0.11 cm per atm HWHM. Pressure shifts in air were determined for a sample of six lines between 948 and 950 nm; these lines shift to lower frequency by an amount comparable to 0.1 of the collision-broadened widths measured in air or N2. The measured intensities of many lines of 300-000 band are much larger than expected from prior computations, in some cases by over an order of magnitude. Coriolis interactions with the stronger 201-000 band appear to be the primary cause of the enhancement of these line intensities.

An infrared optical pacing system for screening cardiac electrophysiology in human cardiomyocytes.

PubMed

McPheeters, Matthew T; Wang, Yves T; Werdich, Andreas A; Jenkins, Michael W; Laurita, Kenneth R

2017-01-01

Human cardiac myocytes derived from pluripotent stem cells (hCM) have invigorated interest in genetic disease mechanisms and cardiac safety testing; however, the technology to fully assess electrophysiological function in an assay that is amenable to high throughput screening has lagged. We describe a fully contactless system using optical pacing with an infrared (IR) laser and multi-site high fidelity fluorescence imaging to assess multiple electrophysiological parameters from hCM monolayers in a standard 96-well plate. Simultaneous multi-site action potentials (FluoVolt) or Ca2+ transients (Fluo4-AM) were measured, from which high resolution maps of conduction velocity and action potential duration (APD) were obtained in a single well. Energy thresholds for optical pacing were determined for cell plating density, laser spot size, pulse width, and wavelength and found to be within ranges reported previously for reliable pacing. Action potentials measured using FluoVolt and a microelectrode exhibited the same morphology and rate of depolarization. Importantly, we show that this can be achieved accurately with minimal damage to hCM due to optical pacing or fluorescence excitation. Finally, using this assay we demonstrate that hCM exhibit reproducible changes in repolarization and impulse conduction velocity for Flecainide and Quinidine, two well described reference compounds. In conclusion, we demonstrate a high fidelity electrophysiological screening assay that incorporates optical pacing with IR light to control beating rate of hCM monolayers.

SAR studies in the Yuma Desert, Arizona: Sand penetration, geology, and the detection of military ordnance debris

USGS Publications Warehouse

Schaber, G.G.

1999-01-01

Synthetic Aperture Radar (SAR) images acquired over part of the Yuma Desert in southwestern Arizona demonstrate the ability of C-band (5.7-cm wavelength), L-band (24.5 cm), and P-band (68 cm) AIRSAR signals to backscatter from increasingly greater depths reaching several meters in blow sand and sandy alluvium. AIRSAR images obtained within the Barry M. Goldwater Bombing and Gunnery Range near Yuma, Arizona, show a total reversal of C- and P-band backscatter contrast (image tone) for three distinct geologic units. This phenomenon results from an increasingly greater depth of radar imaging with increasing radar wavelength. In the case of sandy- and small pebble-alluvium surfaces mantled by up to several meters of blow sand, backscatter increases directly with SAR wavelength as a result of volume scattering from a calcic soil horizon at shallow depth and by volume scattering from the root mounds of healthy desert vegetation that locally stabilize blow sand. AIRSAR images obtained within the military range are also shown to be useful for detecting metallic military ordnance debris that is located either at the surface or covered by tens of centimeters to several meters of blow sand. The degree of detectability of this ordnance increases with SAR wavelength and is clearly maximized on P-band images that are processed in the cross-polarized mode (HV). This effect is attributed to maximum signal penetration at P-band and the enhanced PHV image contrast between the radar-bright ordnance debris and the radar-dark sandy desert. This article focuses on the interpretation of high resolution AIRSAR images but also Compares these airborne SAR images with those acquired from spacecraft sensors such as ERS-SAR and Space Radar Laboratory (SIR-C/X-SAR).Synthetic Aperture Radar (SAR) images acquired over part of the Yuma Desert in southwestern Arizona demonstrate the ability of C-band (5.7-cm wavelength), L-band (24.5 cm), and P-band (68 cm) AIRSAR signals to backscatter from increasingly greater depths reaching several meters in blow sand and sandy alluvium. AIRSAR images obtained within the Barry M. Goldwater Bombing and Gunnery Range near Yuma, Arizona, show a total reversal of C- and P-band backscatter contrast (image tone) for three distinct geologic units. This phenomenon results from an increasingly greater depth of radar imaging with increasing radar wavelength. In the case of sandy- and small pebble-alluvium surfaces mantled by up to several meters of blow sand, backscatter increases directly with SAR wavelength as a result of volume scattering from a calcic soil horizon at shallow depth and by volume scattering from the root mounds of healthy desert vegetation that locally stabilize blow sand. AIRSAR images obtained within the military range are also shown to be useful for detecting metallic military ordnance debris that is located either at the surface or covered by tens of centimeters to several meters of blow sand. The degree of detectability of this ordnance increases with SAR wavelength and is clearly maximized on P-band images that are processed in the cross-polarized mode (HV). This effect is attributed to maximum signal penetration at P-band and the enhanced PHV image contrast between the radar-bright ordnance debris and the radar-dark sandy desert. This article focuses on the interpretation of high resolution AIRSAR images but also compares these airborne SAR images with those acquired from spacecraft sensors such as ERS-SAR and Space Radar Laboratory (SIR-C/X-SAR).

ICD-9-CM and ICD-10-CM mapping of the AAST Emergency General Surgery disease severity grading systems: Conceptual approach, limitations, and recommendations for the future.

PubMed

Utter, Garth H; Miller, Preston R; Mowery, Nathan T; Tominaga, Gail T; Gunter, Oliver; Osler, Turner M; Ciesla, David J; Agarwal, Suresh K; Inaba, Kenji; Aboutanos, Michel B; Brown, Carlos V R; Ross, Steven E; Crandall, Marie L; Shafi, Shahid

2015-05-01

The American Association for the Surgery of Trauma (AAST) recently established a grading system for uniform reporting of anatomic severity of several emergency general surgery (EGS) diseases. There are five grades of severity for each disease, ranging from I (lowest severity) to V (highest severity). However, the grading process requires manual chart review. We sought to evaluate whether International Classification of Diseases, 9th and 10th Revisions, Clinical Modification (ICD-9-CM, ICD-10-CM) codes might allow estimation of AAST grades for EGS diseases. The Patient Assessment and Outcomes Committee of the AAST reviewed all available ICD-9-CM and ICD-10-CM diagnosis codes relevant to 16 EGS diseases with available AAST grades. We then matched grades for each EGS disease with one or more ICD codes. We used the Official Coding Guidelines for ICD-9-CM and ICD-10-CM and the American Hospital Association's "Coding Clinic for ICD-9-CM" for coding guidance. The ICD codes did not allow for matching all five AAST grades of severity for each of the 16 diseases. With ICD-9-CM, six diseases mapped into four categories of severity (instead of five), another six diseases into three categories of severity, and four diseases into only two categories of severity. With ICD-10-CM, five diseases mapped into four categories of severity, seven diseases into three categories, and four diseases into two categories. Two diseases mapped into discontinuous categories of grades (two in ICD-9-CM and one in ICD-10-CM). Although resolution is limited, ICD-9-CM and ICD-10-CM diagnosis codes might have some utility in roughly approximating the severity of the AAST grades in the absence of more precise information. These ICD mappings should be validated and refined before widespread use to characterize EGS disease severity. In the long-term, it may be desirable to develop alternatives to ICD-9-CM and ICD-10-CM codes for routine collection of disease severity characteristics.

Monte Carlo study of x-ray cross talk in a variable resolution x-ray detector

NASA Astrophysics Data System (ADS)

Melnyk, Roman; DiBianca, Frank A.

2003-06-01

A variable resolution x-ray (VRX) detector provides a great increase in the spatial resolution of a CT scanner. An important factor that limits the spatial resolution of the detector is x-ray cross-talk. A theoretical study of the x-ray cross-talk is presented in this paper. In the study, two types of the x-ray cross-talk were considered: inter-cell and inter-arm cross-talk. Both types of the x-ray cross-talk were simulated, using the Monte Carlo method, as functions of the detector field of view (FOV). The simulation was repeated for lead and tungsten separators between detector cells. The inter-cell x-ray cross-talk was maximum at the 34-36 cm FOV, but it was low at small and the maximum FOVs. The inter-arm x-ray cross-talk was high at small and medium FOVs, but it was greatly reduced when variable width collimators were placed on the front surfaces of the detector. The inter-cell, but not inter-arm, x-ray cross-talk was lower for tungsten than for lead separators. From the results, x-ray cross-talk in a VRX detector can be minimized by imaging all objects between 24 cm and 40 cm in diameter with the 40 cm FOV, using tungsten separators, and placing variable width collimators in front of the detector.

Countering Beam Divergence Effects with Focused Segmented Scintillators for High DQE Megavoltage Active Matrix Imagers

PubMed Central

Liu, Langechuan; Antonuk, Larry E; Zhao, Qihua; El-Mohri, Youcef; Jiang, Hao

2012-01-01

The imaging performance of active matrix flat-panel imagers designed for megavoltage imaging (MV AMFPIs) is severely constrained by relatively low x-ray detection efficiency, which leads to a detective quantum efficiency (DQE) of only ~1%. Previous theoretical and empirical studies by our group have demonstrated the potential for addressing this constraint through utilization of thick, two-dimensional, segmented scintillators with optically isolated crystals. However, this strategy is constrained by degradation of high-frequency DQE resulting from spatial resolution loss at locations away from the central beam axis due to oblique incidence of radiation. To address this challenge, segmented scintillators constructed so that the crystals are individually focused toward the radiation source are proposed and theoretically investigated. The study was performed using Monte Carlo simulations of radiation transport to examine the modulation transfer function and DQE of focused segmented scintillators with thicknesses ranging from 5 to 60 mm. The results demonstrate that, independent of scintillator thickness, the introduction of focusing largely restores spatial resolution and DQE performance otherwise lost in thick, unfocused segmented scintillators. For the case of a 60 mm thick BGO scintillator and at a location 20 cm off the central beam axis, use of focusing improves DQE by up to a factor of ~130 at non-zero spatial frequencies. The results also indicate relatively robust tolerance of such scintillators to positional displacements, of up to 10 cm in the source-to-detector direction and 2 cm in the lateral direction, from their optimal focusing position, which could potentially enhance practical clinical use of focused segmented scintillators in MV AMFPIs. PMID:22854009

Development and preliminary results of an in vivo Raman probe for early lung cancer detection

NASA Astrophysics Data System (ADS)

Short, Michael A.; Lam, Stephen; McWilliams, Annette; Zhao, Jianhua; Lui, Harvey; Zeng, Haishan

2008-02-01

Our previous results from Raman spectroscopy studies on ex vivo lung tissue showed the technique had great potential to differentiate between samples with different pathologies. In this work, a fast dispersive-type near-infrared (NIR) Raman spectroscopy system was developed to collect real-time, noninvasive, in vivo human lung spectra. The 785 nm excitation, and the collection of tissue emission were accomplished by using a reusable fiber optic catheter which passed down the instrument channel of a bronchoscope. Filters in two stages blocked laser emission other than 785 nm from reaching the tissue surface, and reduced fiber fluorescence and elastically scattered excitation light from being passed to the spectrometer. The spectrometer itself consisted of one of two holographic gratings with usable frequency ranges of: 700 to 2000 cm -1 and 1500 to 3400 cm -1. The dispersed light was detected by a cooled CCD array consisting of 400 by 1340 pixels. To increase the resolution of the system, while maximizing the throughput, a second fiber bundle, consisting of 54×100 μm diameter fibers connected the catheter to the spectrometer. The fibers in this second bundle were spread out to form a parabolic arc which replaced the conventional entrance slit. This geometry corrected for image aberrations, permitting complete CCD vertical binning, thereby yielding up to a 20-fold improvement in signal-to-noise ratio. The estimated spectral resolution of the system was 9 cm -1 for both gratings. So far we have measured spectra from 20 patients and have seen clear differences between spectra from tumor and normal tissue.

Cavity ring-down spectroscopy using an EC-QCL operating at 7.5 µm for direct monitoring of methane isotopes in air

NASA Astrophysics Data System (ADS)

Maity, Abhijit; Pal, Mithun; Dutta Banik, Gourab; Maithani, Sanchi; Pradhan, Manik

2017-11-01

A number of atmospheric pollutants and greenhouse gases have strong fundamental vibrational transitions within the spectral range of 7.5-8 µm, which marks the region as particularly important for trace gas sensing. Here, we report the development of a mid-infrared continuous-wave (cw) cavity ring-down spectroscopy (CRDS) technique coupled with an external-cavity (EC) mode-hop-free quantum cascade laser (QCL) operating at 7.5 µm. We validated the EC-QCL based high-resolution cw-CRDS system by measuring 12CH4 and 13CH4 isotopes of methane (CH4) which served as a benchmark molecule. The direct, quantitative and selective measurements of 12C and 13C isotopes of CH4 in ambient air as well as in human breath samples in the levels of parts per billion by volume were made by probing one of the strongest fundamental vibrational transitions of CH4 arising from the asymmetric bending (ν 4 band) vibrations of the bonds centred at ~1327.244 cm-1 and ~1332.946 cm-1, respectively. We achieved a noise-equivalent absorption coefficient of 1.86  ×  10-9 cm-1 Hz-1/2 with 100 Hz data acquisition rate for the current cw-CRDS spectrometer. The current high-resolution cw-CRDS system could be further exploited to harness the full advantage of the spectral region covering 7.5-8 µm to monitor several other trace molecular species along with their isotopic compositions.

Potential Biosignatures Visualization with the Close-Up Imager CLUPI for EXOMARS

NASA Astrophysics Data System (ADS)

Josset, J. L.; Westall, F.; Hofmann, B. A.; Beauvivre, S.

The CLose-UP Imager CLUPI imaging experiment will be designed to obtain high-resolution colour and stereo images of rocks from the ExoMars rover Pasteur payload The close-up imager is a robotic equivalent of one of the most useful instruments of the field geologist the hand lens Imaging of surfaces of rocks soils and wind drift deposits is crucial for the understanding of the geological context of any site where the Pasteur rover will be active on Mars The purpose of the Close-up imager is to look an area of about 4 cm x 4 cm of the rocks at a focus distance of 10 cm With a resolution of approx 35 micrometer pixel many kinds of rock surface and internal structures can be visualized crystals in igneous rocks fracture mineralization secondary minerals details of the surface morphology sediment components sedimentary structures soil particles It is conceivable that even textures resulting from ancient biological activity can be seen such as fine lamination due to microbial mats stromatolites and textures resulting from colonies of filamentous microbes CLUPI is a powerful highly integrated miniaturized low-power robust imaging system with no mobile part able to operate at very low temperature -120oC The opto-mechanical interfaces will be a smart assembly in titanium sustaining wide temperature range The concept benefits from well-proven heritage Proba Rosetta MarsExpress and Smart-1 missions The close-up imager CLUPI on the ExoMars Rover will be described together with its capabilities to provide important information significantly

21SSD: a public data base of simulated 21-cm signals from the epoch of reionization

NASA Astrophysics Data System (ADS)

Semelin, B.; Eames, E.; Bolgar, F.; Caillat, M.

2017-12-01

The 21-cm signal from the epoch of reionization (EoR) is expected to be detected in the next few years, either with existing instruments or by the upcoming SKA and HERA projects. In this context, there is a pressing need for publicly available high-quality templates covering a wide range of possible signals. These are needed both for end-to-end simulations of the up-coming instruments and to develop signal analysis methods. We present such a set of templates, publicly available, for download at 21ssd.obspm.fr. The data base contains 21-cm brightness temperature lightcones at high and low resolution, and several derived statistical quantities for 45 models spanning our choice of 3D parameter space. These data are the result of fully coupled radiative hydrodynamic high-resolution (10243) simulations performed with the LICORICE code. Both X-ray and Lyman line transfer are performed to account for heating and Wouthuysen-Field coupling fluctuations. We also present a first exploitation of the data using the power spectrum and the pixel distribution function (PDF) computed from lightcone data. We analyse how these two quantities behave when varying the model parameters while taking into account the thermal noise expected of a typical SKA survey. Finally, we show that the noiseless power spectrum and PDF have different - and somewhat complementary - abilities to distinguish between different models. This preliminary result will have to be expanded to the case including thermal noise. This type of results opens the door to formulating an optimal sampling of the parameter space, dependent on the chosen diagnostics.

Handheld, rapidly switchable, anterior/posterior segment swept source optical coherence tomography probe

PubMed Central

Nankivil, Derek; Waterman, Gar; LaRocca, Francesco; Keller, Brenton; Kuo, Anthony N.; Izatt, Joseph A.

2015-01-01

We describe the first handheld, swept source optical coherence tomography (SSOCT) system capable of imaging both the anterior and posterior segments of the eye in rapid succession. A single 2D microelectromechanical systems (MEMS) scanner was utilized for both imaging modes, and the optical paths for each imaging mode were optimized for their respective application using a combination of commercial and custom optics. The system has a working distance of 26.1 mm and a measured axial resolution of 8 μm (in air). In posterior segment mode, the design has a lateral resolution of 9 μm, 7.4 mm imaging depth range (in air), 4.9 mm 6dB fall-off range (in air), and peak sensitivity of 103 dB over a 22° field of view (FOV). In anterior segment mode, the design has a lateral resolution of 24 μm, imaging depth range of 7.4 mm (in air), 6dB fall-off range of 4.5 mm (in air), depth-of-focus of 3.6 mm, and a peak sensitivity of 99 dB over a 17.5 mm FOV. In addition, the probe includes a wide-field iris imaging system to simplify alignment. A fold mirror assembly actuated by a bi-stable rotary solenoid was used to switch between anterior and posterior segment imaging modes, and a miniature motorized translation stage was used to adjust the objective lens position to correct for patient refraction between −12.6 and + 9.9 D. The entire probe weighs less than 630 g with a form factor of 20.3 x 9.5 x 8.8 cm. Healthy volunteers were imaged to illustrate imaging performance. PMID:26601014

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.

First imaging results from Apertif, a phased-array feed for WSRT

NASA Astrophysics Data System (ADS)

Adams, Elizabeth A.; Adebahr, Björn; de Blok, Willem J. G.; Hess, Kelley M.; Hut, Boudewijn; Lucero, Danielle M.; Maccagni, Filippo; Morganti, Raffaella; Oosterloo, Tom; Staveley-Smith, Lister; van der Hulst, Thijs; Verheijen, Marc; Verstappen, Joris

2017-01-01

Apertif is a phased-array feed for the Westerbork Synthesis Radio Telescope (WSRT), increasing the field of view of the telescope by a factor of twenty-five. In 2017, three legacy surveys will commence: a shallow imaging survey, a medium-deep imaging survey, and a pulsars and fast transients survey. The medium-deep imaging survey will include coverage of the northern Herschel Atlas field, the CVn region, HetDex, and the Perseus-Pisces supercluster. The shallow imaging survey increases overlap with HetDex, has expanded coverage of the Perseus-Pisces supercluster, and includes part of the Zone of Avoidance. Both imaging surveys are coordinating with MaNGA and will have WEAVE follow-up. The imaging surveys will be done in full polarization over the frequency range 1130-1430 MHz, which corresponds to redshifts of z=0-0.256 for neutral hydrogen (HI). The spectral resolution is 12.2 kHz, or an HI velocity resolution of 2.6 km/s at z=0 and 3.2 km/s at z=0.256. The full resolution images will have a beam size of 15"x15"/sin(declination), and tapered data products (i.e., 30" resolution images) will also be available. The shallow survey will cover ~3500 square degrees with a four-sigma HI imaging sensitivity of 2.5x10^20 atoms cm^-2 (20 km/s linewidth) at the highest resolution and a continuum sensitivity of 15 uJy/beam (11 uJy/beam for polarization data). The current plan calls for the medium deep survey to cover 450 square degrees and provide an HI imaging sensitivity of 1.0x10^20 atoms cm^-2 at the highest resolution and a continuum sensitivity of 6 uJy/beam, close to the confusion limit (4 uJy/beam for polarization data, not confusion limited). Up-to-date information on Apertif and the planned surveys can be found at: http://www.apertif.nl.Commissioning of the Apertif instrument is currently underway. Here we present first results from the image commissioning, including the detection of HI absorption plus continuum and HI imaging. These results highlight the data quality that will be achieved for the surveys.

Negative-tone imaging with EUV exposure toward 13nm hp

NASA Astrophysics Data System (ADS)

Tsubaki, Hideaki; Nihashi, Wataru; Tsuchihashi, Toru; Yamamoto, Kei; Goto, Takahiro

2016-03-01

Negative-tone imaging (NTI) with EUV exposure has major advantages with respect to line-width roughness (LWR) and resolution due in part to polymer swelling and favorable dissolution mechanics. In NTI process, both resist and organic solvents play important roles in determining lithography performances. The present study describes novel chemically amplified resist materials based on NTI technology with EUV using a specific organic solvents. Lithographic performances of NTI process were described in this paper under exposures using ASML NXE:3300 EUV scanner at imec. It is emphasized that 14 nm hp was nicely resolved under exposure dose of 37 mJ/cm2 without any bridge and collapse, which are attributed to the low swelling character of NTI process. Although 13 nm hp resolution was potentially obtained, a pattern collapse still restricts its resolution in case coating resist film thickness is 40 nm. Dark mask limitation due mainly to mask defectivity issue makes NTI with EUV favorable approach for printing block mask to produce logic circuit. A good resolution of CD-X 21 nm/CD-Y 32 nm was obtained for block mask pattern using NTI with usable process window and dose of 49 mJ/cm2. Minimum resolution now reaches CD-X 17 nm / CD-Y 23 nm for the block. A 21 nm block mask resolution was not affected by exposure dose and explored toward low dose down to 18 mJ/cm2 by reducing quencher loading. In addition, there was a negligible amount of increase in LCDU for isolated dot pattern when decreasing exposure dose from 66 mJ/cm2 to 24 mJ/cm2. On the other hand, there appeared tradeoff relationship between LCDU and dose for dense dot pattern, indicating photon-shot noise restriction, but strong dependency on patterning features. Design to improve acid generation efficiency was described based on acid generation mechanism in traditional chemically amplified materials which contains photo-acid generator (PAG) and polymer. Conventional EUV absorber comprises of organic compounds is expected to have 1.6 times higher EUV absorption than polyhydroxystyrene based on calculation. However, observed value of acid amount was comparable or significantly worse than polyhydroxystyrene.

High resolution spectroscopy of jet cooled phenyl radical: The ν1 and ν2 a1 symmetry C-H stretching modes

NASA Astrophysics Data System (ADS)

Chang, Chih-Hsuan; Nesbitt, David J.

2016-07-01

A series of CH stretch modes in phenyl radical (C6H5) has been investigated via high resolution infrared spectroscopy at sub-Doppler resolution (˜60 MHz) in a supersonic discharge slit jet expansion. Two fundamental vibrations of a1 symmetry, ν1 and ν2, are observed and rotationally analyzed for the first time, corresponding to in-phase and out-of-phase symmetric CH stretch excitation at the ortho/meta/para and ortho/para C atoms with respect to the radical center. The ν1 and ν2 band origins are determined to be 3073.968 50(8) cm-1 and 3062.264 80(7) cm-1, respectively, which both agree within 5 cm-1 with theoretical anharmonic scaling predictions based on density functional B3LYP/6-311g++(3df,3dp) calculations. Integrated band strengths for each of the CH stretch bands are analyzed, with the relative intensities agreeing remarkably well with theoretical predictions. Frequency comparison with previous low resolution Ar-matrix spectroscopy [A. V. Friderichsen et al., J. Am. Chem. Soc. 123, 1977 (2001)] reveals a nearly uniform Δν ≈ + 10-12 cm-1 blue shift between gas phase and Ar matrix values for ν1 and ν2. This differs substantially from the much smaller red shift (Δν ≈ - 1 cm-1) reported for the ν19 mode, and suggests a simple physical model in terms of vibrational mode symmetry and crowding due to the matrix environment. Finally, the infrared phenyl spectra are well described by a simple asymmetric rigid rotor Hamiltonian and show no evidence for spectral congestion due to intramolecular vibrational coupling, which bodes well for high resolution studies of other ring radicals and polycyclic aromatic hydrocarbons. In summary, the combination of slit jet discharge methods with high resolution infrared lasers enables spectroscopic investigation of even highly reactive combustion and interstellar radical intermediates under gas phase, jet-cooled (Trot ≈ 11 K) conditions.

Ultraviolet observation of nova LMC 2012 with STIS/HST

NASA Astrophysics Data System (ADS)

Shore, S. N.; Schwarz, G.; Page, K.; Osborne, J. P.; Starrfield, S.; Walter, F.; Woodward, C. E.; Bode, M.; Ness, J.-U.

2012-05-01

Nova LMC 2012 (ATel #4002, #4043) was observed with STIS on the Hubble Space Telescope on 2012 May 7 (MJD 56055) at three settings with medium resolution (E140M, E230M, with exposure times of 724 sec per setting) covering 1150 - 3000 A. There is only one strong emission line in the entire spectral range: N V 1240 (S/N ~ 15, 0.5 A binning, integrated (not dereddened) flux of 1.2E-13 erg/s/cm^2, FWZI ~ 7500 km/s); the blue wing is blended with Ly-alpha absorption (MW+LMC).

Detection of Gaseous Methane on Pluto

NASA Technical Reports Server (NTRS)

Young, Leslie; Tokunaga, Alan; Elliot, J.; deBergh, Catherine; Owen, Tobias; Witteborn, Fred C. (Technical Monitor)

1995-01-01

We obtained Pluto's spectrum using the CSHELL echelle spectrograph at NASA's IRTF on Mauna Kea, on 25-26 May 1992, with a spectral resolution of 13,300. The spectral range (5998 - 6018 per centimeter, or 1661.8 - 1666.9 nm) includes the R(0) and the Q(1) - Q(9) lines of the 2v3 band of methane. The resulting spectrum shows the first detection of gaseous methane on Pluto, with a column height of 1.20 (sup +3.15) (sub -0.87) cm-A (3.22 (sup +8.46) (sub -2.34) x 10(exp 19) molecule per square centimeter)).

The nuclear radiation monitor for the Spacelab/Shuttle

NASA Technical Reports Server (NTRS)

Fishman, G. J.

1978-01-01

A 5 inch by 5 inch diameter sodium iodide scintillation crystal, viewed by a 5 inch photomultiplier was designed to be mounted near the center of the shuttle payload bay to quantitatively measure the neutron and gamma ray environment during the second Spacelab mission. The expected energy resolution is 8% FWHM at 662 keV. The detector will operate in an energy range from 0.1 to 20 MeV. A charged anticoincidence shield consisting of a 1 cm thick plastic scintillator viewed by three 2 inch photomultiplier tubes, covers the crystal detector which has nearly omnidirectional response.

Structures and textures of the Murchison and Mighei carbonaceous chondrite matrices

NASA Technical Reports Server (NTRS)

Mackinnon, I. D. R.

1980-01-01

High-resolution transmission electron microscopy has confirmed earlier observations that the character of the Murchison and Mighei fine-grained matrices is complex in mineralogy and texture. Layer structure minerals occur as planar laths, rounded grains or subhedral grains, and range in size from less than 100 A to about 1 micrometer. Serpentine-type and brucite-type structures predominate in the CM matrices. The occurrence of Povlen chrysolite and a vein of disordered mixed-layer and brucite-type material cutting a large lizardite-type grain suggests that at least some of the matrix materials were formed by alteration of preexisting material.

Interferometric fibre-optic curvature sensing for structural, directional vibration measurements

NASA Astrophysics Data System (ADS)

Kissinger, Thomas; Chehura, Edmon; James, Stephen W.; Tatam, Ralph P.

2017-06-01

Dynamic fibre-optic curvature sensing using fibre segment interferometry is demonstrated using a cost-effective rangeresolved interferometry interrogation system. Differential strain measurements from four fibre strings, each containing four fibre segments of gauge length 20 cm, allow the inference of lateral vibrations as well as the direction of the vibration of a cantilever test object. Dynamic tip displacement resolutions in the micrometre range over a 21 kHz interferometric bandwidth demonstrate the suitability of this approach for highly sensitive fibre-optic directional vibration measurements, complementing existing laser vibrometry techniques by removing the need for side access to the structure under test.

Characterisation Of Polysacharides And Lipids From Selected Green Algae Species By FTIR-ATR Spectroscopy

NASA Astrophysics Data System (ADS)

Bartošová, Alica; Blinová, Lenka; Gerulová, Kristína

2015-06-01

Fourier transform infrared (FTIR) spectroscopy was used in this study to identify and determine spectral features of Chromochloris zofingiensis (Dönz) Fucíková et L.A. Lewis (SAG 211-14, Gottingen, Germany), Acutodesmus obliguus (Turpin) Hegewald (SAG 276-1, Gottingen, Germany) and Chlorella sorokiniana (K. Brandt) Pröschold et Darienko (SAG 211-40c, Gottingen, Germany). Polysaccharides and lipids from these three algae species were determined using Fourier Transformed Infrared Spectroscopy (FTIR) with ATR accessory with diamante crystal in spectral range from 400 - 4000 cm-1 and resolution 4.

Helium broadened propane absorption cross sections in the far-IR

NASA Astrophysics Data System (ADS)

Wong, A.; Billinghurst, B.; Bernath, P. F.

2017-09-01

Infrared absorption spectra for pure and He broadened propane have been recorded in the far-IR region (650-1300 cm-1) at the Canadian Light Source (CLS) facility using either the synchrotron or internal glowbar source depending on the required resolution. The measurements were made for 4 temperatures in the range 202-292 K and for 3 pressures of He broadening gas up to 100 Torr. Infrared absorption cross sections are derived from the spectra and the integrated cross sections are within 10 % of the corresponding values from the Pacific Northwest National Laboratory (PNNL) for all temperatures and pressures.

Simulating the impact of X-ray heating during the cosmic dawn

NASA Astrophysics Data System (ADS)

Ross, Hannah E.; Dixon, Keri L.; Iliev, Ilian T.; Mellema, Garrelt

2017-07-01

Upcoming observations of the 21-cm signal from the epoch of reionization will soon provide the first direct detection of this era. This signal is influenced by many astrophysical effects, including long-range X-ray heating of the intergalactic gas. During the preceding cosmic dawn era, the impact of this heating on the 21-cm signal is particularly prominent, especially before spin temperature saturation. We present the largest volume (349 Mpc comoving = 244 h-1Mpc) full numerical radiative transfer simulations to date of this epoch which include the effects of helium and multifrequency heating, both with and without X-ray sources. We show that X-ray sources contribute significantly to early heating of the neutral intergalactic medium and, hence, to the corresponding 21-cm signal. The inclusion of hard, energetic radiation yields an earlier, extended transition from absorption to emission compared to the stellar-only case. The presence of X-ray sources decreases the absolute value of the mean 21-cm differential brightness temperature. These hard sources also significantly increase the 21-cm fluctuations compared to the common assumption of temperature saturation. The 21-cm differential brightness temperature power spectrum is initially boosted on large scales, before decreasing on all scales. Compared to the case of the cold, unheated intergalactic medium, the signal has lower rms fluctuations and increased non-Gaussianity, as measured by the skewness and kurtosis of the 21-cm probability distribution functions. Images of the 21-cm signal with resolution around 11 arcmin still show fluctuations well above the expected noise for deep integrations with the SKA1-Low, indicating that direct imaging of the X-ray heating epoch could be feasible.

TH-C-19A-05: Evaluation of a New Reusable 3D Dosimeter

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

Juang, T; Adamovics, J; Oldham, M

Purpose: PRESAGE is a radiochromic plastic which has demonstrated strong potential for high resolution single-use 3D dosimetry. This study evaluates a new PRESAGE formulation (Presage-RU) in which the radiochromic response is reversible (the dosimeter optically clears after irradiation), enabling the potential for reusability. Methods: Presage-RU dose response and optical-clearing rates were evaluated in both small volume dosimeters (1×1×4.5cm) and a larger cylindrical dosimeter (8cm diameter, 4.5cm length). All dosimeters were allowed to fully optically clear in dark, room temperature conditions between irradiations. Dose response was determined by irradiating small volume samples from 0–8.0Gy and measuring change in optical density. Themore » cylindrical dosimeter was irradiated with a simple 4-field box plan (parallel opposed pairs of 4cm×4cm AP-PA beams and 2cm×4cm lateral beams) to 20Gy. High resolution 3D dosimetry was achieved utilizing optical-CT readout. Readings were tracked up to 14 days to characterize optical clearing. Results: Initial irradiation yielded a response of 0.0119△OD/(Gy*cm) while two subsequent reirradiations yielded a lower but consistent response of 0.0087△OD/(Gy*cm). Strong linearity of dose response was observed for all irradiations. In the large cylindrical dosimeter, the integral dose within the high dose region exhibited an exponential decay in signal over time (halflife= 23.9 hours), with the dosimeter effectively cleared (0.04% of the initial signal) after 10 days. Subsequent irradiation resulted in 19.5% lower initial signal but demonstrated that the exponential clearing rate remained consistent. Results of additional subsequent irradiations will also be presented. Conclusion: This work introduces a new re-usable radiochromic dosimeter (Presage-RU) compatible with high resolution (sub-millimeter) 3D dosimetry. Sensitivity of the initial radiation was observed to be slightly higher than subsequent irradiations, but the clearing time remained constant, indicating the dosimeter can be re-used after 10 days. Presage-RU has potential to dramatically improve cost-effectiveness and thereby lower the barrier for implementing comprehensive, high resolution 3D dosimetry. John Adamovics is the president of Heuris Inc., which commercializes PRESAGE.« less

SU-C-207A-01: A Novel Maximum Likelihood Method for High-Resolution Proton Radiography/proton CT

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

Collins-Fekete, C; Centre Hospitalier University de Quebec, Quebec, QC; Mass General Hospital

2016-06-15

Purpose: Multiple Coulomb scattering is the largest contributor to blurring in proton imaging. Here we tested a maximum likelihood least squares estimator (MLLSE) to improve the spatial resolution of proton radiography (pRad) and proton computed tomography (pCT). Methods: The object is discretized into voxels and the average relative stopping power through voxel columns defined from the source to the detector pixels is optimized such that it maximizes the likelihood of the proton energy loss. The length spent by individual protons in each column is calculated through an optimized cubic spline estimate. pRad images were first produced using Geant4 simulations. Anmore » anthropomorphic head phantom and the Catphan line-pair module for 3-D spatial resolution were studied and resulting images were analyzed. Both parallel and conical beam have been investigated for simulated pRad acquisition. Then, experimental data of a pediatric head phantom (CIRS) were acquired using a recently completed experimental pCT scanner. Specific filters were applied on proton angle and energy loss data to remove proton histories that underwent nuclear interactions. The MTF10% (lp/mm) was used to evaluate and compare spatial resolution. Results: Numerical simulations showed improvement in the pRad spatial resolution for the parallel (2.75 to 6.71 lp/cm) and conical beam (3.08 to 5.83 lp/cm) reconstructed with the MLLSE compared to averaging detector pixel signals. For full tomographic reconstruction, the improved pRad were used as input into a simultaneous algebraic reconstruction algorithm. The Catphan pCT reconstruction based on the MLLSE-enhanced projection showed spatial resolution improvement for the parallel (2.83 to 5.86 lp/cm) and conical beam (3.03 to 5.15 lp/cm). The anthropomorphic head pCT displayed important contrast gains in high-gradient regions. Experimental results also demonstrated significant improvement in spatial resolution of the pediatric head radiography. Conclusion: The proposed MLLSE shows promising potential to increase the spatial resolution (up to 244%) in proton imaging.« less

Cloud optical properties from satellites over Europe: CM SAF vs CERES

NASA Astrophysics Data System (ADS)

Konstantinou, Athanasia; Alexandri, Georgia; Balis, Dimitris

2017-04-01

In this work, the macro and micro physical properties of liquid and ice clouds over Europe are examined for the 8-year period 2004-2011. For the scopes of this research, high resolution (0.05x0.05 degree) satellite-based observations from CM SAF (Satellite Application Facility on Climate Monitoring) and coarse resolution (1x1 degree) data from CERES (Clouds and the Earth's Radiant Energy System) are utilized. The spatial and temporal patterns of the bias between the two products are examined. It is found that the difference between CM SAF and CERES cloud fractional cover (CFC) is 10% while cloud optical thickness (COT) from CM SAF is generally lower than CERES by 10 %. The effective radius of liquid (Rel) and ice (Rei) clouds is also examined. For the region of interest, CM SAF Rel is 12% higher while CM SAF Rei is lower by 20% than that of CERES. Intercomparison studies like the one presented here help us to get an insight into the capabilities and limitation of the cloud satellite products which are currently in use by the scientific community.

Soil Organic Carbon Estimation and Mapping Using "on-the-go" VisNIR Spectroscopy

NASA Astrophysics Data System (ADS)

Brown, D. J.; Bricklemyer, R. S.; Christy, C.

2007-12-01

Soil organic carbon (SOC) and other soil properties related to carbon sequestration (eg. soil clay content and mineralogy) vary spatially across landscapes. To cost effectively capture this variability, new technologies, such as Visible and Near Infrared (VisNIR) spectroscopy, have been applied to soils for rapid, accurate, and inexpensive estimation of SOC and other soil properties. For this study, we evaluated an "on the go" VisNIR sensor developed by Veris Technologies, Inc. (Salinas, KS) for mapping SOC, soil clay content and mineralogy. The Veris spectrometer spanned 350 to 2224 nm with 8 nm spectral resolution, and 25 spectra were integrated every 2 seconds resulting in 3 -5 m scanning distances on the ground. The unit was mounted to a mobile sensor platform pulled by a tractor, and scanned soils at an average depth of 10 cm through a quartz-sapphire window. We scanned eight 16.2 ha (40 ac) wheat fields in north central Montana (USA), with 15 m transect intervals. Using random sampling with spatial inhibition, 100 soil samples from 0-10 cm depths were extracted along scanned transects from each field and were analyzed for SOC. Neat, sieved (<2 mm) soil sample materials were also scanned in the lab using an Analytical Spectral Devices (ASD, Boulder, CO, USA) Fieldspec Pro FR spectroradiometer with a spectral range of 350-2500 and spectral resolution of 2-10 nm. The analyzed samples were used to calibrate and validate a number of partial least squares regression (PLSR) VisNIR models to compare on-the-go scanning vs. higher spectral resolution laboratory spectroscopy vs. standard SOC measurement methods.

Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) in the discrimination of normal and oral cancer blood plasma

NASA Astrophysics Data System (ADS)

Pachaiappan, Rekha; Prakasarao, Aruna; Singaravelu, Ganesan

2017-02-01

Oral cancer is the most frequent type of cancer that occurs with 75000 to 80000 new cases reported every year in India. The carcinogens from tobacco and related products are the main cause for the oral cancer. ATR-FTIR method is label free, fast and cost-effective diagnostic method would allow for rapid diagnostic results in earlier stages by the minimal chemical changes occur in the biological metabolites available in the blood plasma. The present study reports the use of ATR-FTIR data with advanced statistical model (LDA-ANN) in the diagnosis of oral cancer from normal with better accuracy. The infrared spectra were acquired on ATR-FTIR Jasco spectrophotometer at 4 cm-1 resolution, 30 scans, in the 1800-900 cm-1 spectral range. Each sample had 5 spectra recorded from each blood plasma sample. The spectral data were routed through the multilayer perception of artificial neural network to evaluate for the statistical efficacy. Among the spectral data it was found that amide II (1486 cm-1) and lipid (1526 cm-1) affords about 90 % in the discrimination between groups using LDA. These preliminary results indicate that ATR-FTIR is useful to differentiate normal subject from oral cancer patients using blood plasma.

Fault detection technique for wavelength division multiplexing passive optical network using chaotic fiber laser

NASA Astrophysics Data System (ADS)

Xu, Naijun; Yang, Lingzhen; Zhang, Juan; Zhang, Xiangyuan; Wang, Juanfen; Zhang, Zhaoxia; Liu, Xianglian

2014-03-01

We propose a fault localization method for wavelength division multiplexing passive optical network (WDM-PON). A proof-of-concept experiment was demonstrated by utilizing the wavelength tunable chaotic laser generated from an erbium-doped fiber ring laser with a manual tunable fiber Bragg grating (TFBG) filter. The range of the chaotic lasing wavelength can cover the C-band. Basing on the TFBG filter, we can adjust the wavelength of the chaotic laser to match the WDM-PON channel with identical wavelength. We determined the fault location by calculating the cross-correlation between the reference and return signals. Analysis of the characteristics of the wavelength tunable chaotic laser showed that the breakpoint, the loose connector, and the mismatch connector could be precisely located. A dynamic range of approximately 23.8 dB and a spatial resolution of 4 cm, which was independent of the measuring range, were obtained.

3D range-gated super-resolution imaging based on stereo matching for moving platforms and targets

NASA Astrophysics Data System (ADS)

Sun, Liang; Wang, Xinwei; Zhou, Yan

2017-11-01

3D range-gated superresolution imaging is a novel 3D reconstruction technique for target detection and recognition with good real-time performance. However, for moving targets or platforms such as airborne, shipborne, remote operated vehicle and autonomous vehicle, 3D reconstruction has a large error or failure. In order to overcome this drawback, we propose a method of stereo matching for 3D range-gated superresolution reconstruction algorithm. In experiment, the target is a doll of Mario with a height of 38cm at the location of 34m, and we obtain two successive frame images of the Mario. To confirm our method is effective, we transform the original images with translation, rotation, scale and perspective, respectively. The experimental result shows that our method has a good result of 3D reconstruction for moving targets or platforms.

Stand-alone polarization-modulation infrared reflection absorption spectroscopy instrument optimized for the study of catalytic processes at elevated pressures

DOE PAGES

Kestell, John D.; Mudiyanselage, Kumudu; Ye, Xinyi; ...

2017-10-01

This article describes the design and construction of a compact, “user-friendly” polarization-modulation infrared reflection absorption spectroscopy (PM-IRRAS) instrument at the Center for Functional Nanomaterials (CFN) of Brookhaven National Laboratory, which allows studying surfaces at pressures ranging from ultra-high vacuum to 100 Torr. Surface infrared spectroscopy is ideally suited for studying these processes as the vibrational frequencies of the IR chromophores are sensitive to the nature of the bonding environment on the surface. Relying on the surface selection rules, by modulating the polarization of incident light, it is possible to separate the contributions from the isotropic gas or solution phase, frommore » the surface bound species. A spectral frequency range between 1000 cm -1 and 4000 cm -1 can be acquired. While typical spectra with a good signal to noise ratio can be obtained at elevated pressures of gases in ~2 min at 4 cm -1 resolution, we have also acquired higher resolution spectra at 0.25 cm -1 with longer acquisition times. By way of verification, CO uptake on a heavily oxidized Ru(0001) sample was studied. As part of this test study, the presence of CO adsorbed on Ru bridge sites was confirmed, in agreement with previous ambient pressure X ray photoelectron spectroscopy studies. In terms of instrument performance, it was also determined that the gas phase contribution from CO could be completely removed even up to pressures close to 100 Torr. A second test study demonstrated the use of the technique for studying morphological properties of a spin coated polymer on a conductive surface. Note that this is a novel application of this technique. In this experiment, the polarization of incident light was modulated manually (vs. through a photoelastic modulator). It was demonstrated, in good agreement with the literature, that the polymer chains preferentially lie parallel with the surface. This PM-IRRAS system is small, modular, and easily reconfigurable. It also features a “vacuum suitcase” that allows for the integration of the PM-IRRAS system with the rest of the suite of instrumentation at our laboratory available to external users through the CFN user proposal system.« less

Stand-alone polarization-modulation infrared reflection absorption spectroscopy instrument optimized for the study of catalytic processes at elevated pressures

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

Kestell, John D.; Mudiyanselage, Kumudu; Ye, Xinyi

This article describes the design and construction of a compact, “user-friendly” polarization-modulation infrared reflection absorption spectroscopy (PM-IRRAS) instrument at the Center for Functional Nanomaterials (CFN) of Brookhaven National Laboratory, which allows studying surfaces at pressures ranging from ultra-high vacuum to 100 Torr. Surface infrared spectroscopy is ideally suited for studying these processes as the vibrational frequencies of the IR chromophores are sensitive to the nature of the bonding environment on the surface. Relying on the surface selection rules, by modulating the polarization of incident light, it is possible to separate the contributions from the isotropic gas or solution phase, frommore » the surface bound species. A spectral frequency range between 1000 cm -1 and 4000 cm -1 can be acquired. While typical spectra with a good signal to noise ratio can be obtained at elevated pressures of gases in ~2 min at 4 cm -1 resolution, we have also acquired higher resolution spectra at 0.25 cm -1 with longer acquisition times. By way of verification, CO uptake on a heavily oxidized Ru(0001) sample was studied. As part of this test study, the presence of CO adsorbed on Ru bridge sites was confirmed, in agreement with previous ambient pressure X ray photoelectron spectroscopy studies. In terms of instrument performance, it was also determined that the gas phase contribution from CO could be completely removed even up to pressures close to 100 Torr. A second test study demonstrated the use of the technique for studying morphological properties of a spin coated polymer on a conductive surface. Note that this is a novel application of this technique. In this experiment, the polarization of incident light was modulated manually (vs. through a photoelastic modulator). It was demonstrated, in good agreement with the literature, that the polymer chains preferentially lie parallel with the surface. This PM-IRRAS system is small, modular, and easily reconfigurable. It also features a “vacuum suitcase” that allows for the integration of the PM-IRRAS system with the rest of the suite of instrumentation at our laboratory available to external users through the CFN user proposal system.« less

VizieR Online Data Catalog: LMC and Cen A 1.3-10GHz polarization behavior (Anderson+, 2016)

NASA Astrophysics Data System (ADS)

Anderson, C. S.; Gaensler, B. M.; Feain, I. J.

2016-08-01

The targets for our study were selected from among two archival polarization data sets, which were observed and processed by several independent groups. i.e. LMC observations spanning from 1994 Oct to 1996 Jan in 1.328-1.432GHz band; Cen A observations spanning from 2006 Dec to 2008 Feb in 1.296-1.480GHz band. We observed the 40 sample sources using the Australia Telescope Compact Array (ATCA) over 1.1-3.1GHz (16cm), 4.5-6.5GHz (6cm), and 8.0-10.0GHz (3cm) in full polarization with a nominal 1MHz channel resolution between 2012 Feb 10-12 and 2012 Aug 17-19. We imaged each source in Stokes I, Q, and U at 20MHz intervals through the 16 and 6cm bands, and at a substantially coarser resolution of 200MHz in the 3cm band. See sections 2 and 3 for further explanations. (2 data files).

Coping with Higher Sea Levels and Increased Coastal Flooding in New York City. Chapter 13

NASA Technical Reports Server (NTRS)

Gornitz, Vivien; Horton, Radley; Bader, Daniel A.; Orton, Philip; Rosenzweig, Cynthia

2017-01-01

The 837 km New York City shoreline is lined by significant economic assets and dense population vulnerable to sea level rise and coastal flooding. After Hurricane Sandy in 2012, New York City developed a comprehensive plan to mitigate future climate risks, drawing upon the scientific expertise of the New York City Panel on Climate Change (NPCC), a special advisory group comprised of university and private-sector experts. This paper highlights current NPCC findings regarding sea level rise and coastal flooding, with some of the City's ongoing and planned responses. Twentieth century sea level rise in New York City (2.8 cm/decade) exceeded the global average (1.7 cm/decade), underscoring the enhanced regional risk to coastal hazards. NPCC (2015) projects future sea level rise at the Battery of 28 - 53 cm by the 2050s and 46 - 99 cm by the 2080s, relative to 2000 - 2004 (mid-range, 25th - 75th percentile). High-end SLR estimates (90th percentile) reach 76 cm by the 2050s, and 1.9 m by 2100. Combining these projections with updated FEMA flood return period curves, assuming static flood dynamics and storm behavior, flood heights for the 100-year storm (excluding waves) attain 3.9-4.5 m (mid-range), relative to the NAVD88 tidal datum, and 4.9 m (high end) by the 2080s, up from 3.4 m in the 2000s. Flood heights with a 1% annual chance of occurrence in the 2000s increase to 2.0 - 5.4% (mid-range) and 12.7% per year (high-end), by the 2080s. Guided by NPCC (2013, 2015) findings, New York City has embarked on a suite of initiatives to strengthen coastal defenses, employing various approaches tailored to specific neighborhood needs. NPCC continues its collaboration with the city to investigate vulnerability to extreme climate events, including heat waves, inland floods and coastal storms. Current research entails higher-resolution neighborhood-level coastal flood mapping, changes in storm characteristics, surge height interactions with sea level rise, and stronger engagement with stakeholders and community-based organizations.

Microchannel plate detector technology potential for LUVOIR and HabEx

NASA Astrophysics Data System (ADS)

Siegmund, O. H. W.; Ertley, C.; Vallerga, J. V.; Schindhelm, E. R.; Harwit, A.; Fleming, B. T.; France, K. C.; Green, J. C.; McCandliss, S. R.; Harris, W. M.

2017-08-01

Microchannel plate (MCP) detectors have been the detector of choice for ultraviolet (UV) instruments onboard many NASA missions. These detectors have many advantages, including high spatial resolution (<20 μm), photon counting, radiation hardness, large formats (up to 20 cm), and ability for curved focal plane matching. Novel borosilicate glass MCPs with atomic layer deposition combine extremely low backgrounds, high strength, and tunable secondary electron yield. GaN and combinations of bialkali/alkali halide photocathodes show promise for broadband, higher quantum efficiency. Cross-strip anodes combined with compact ASIC readout electronics enable high spatial resolution over large formats with high dynamic range. The technology readiness levels of these technologies are each being advanced through research grants for laboratory testing and rocket flights. Combining these capabilities would be ideal for UV instruments onboard the Large UV/Optical/IR Surveyor (LUVOIR) and the Habitable Exoplanet Imaging Mission (HABEX) concepts currently under study for NASA's Astrophysics Decadal Survey.

MiX: a position sensitive dual-phase liquid xenon detector

NASA Astrophysics Data System (ADS)

Stephenson, S.; Haefner, J.; Lin, Q.; Ni, K.; Pushkin, K.; Raymond, R.; Schubnell, M.; Shutty, N.; Tarlé, G.; Weaverdyck, C.; Lorenzon, W.

2015-10-01

The need for precise characterization of dual-phase xenon detectors has grown as the technology has matured into a state of high efficacy for rare event searches. The Michigan Xenon detector was constructed to study the microphysics of particle interactions in liquid xenon across a large energy range in an effort to probe aspects of radiation detection in liquid xenon. We report the design and performance of a small 3D position sensitive dual-phase liquid xenon time projection chamber with high light yield (Ly122=15.2 pe/keV at zero field), long electron lifetime (τ > 200 μs), and excellent energy resolution (σ/E = 1% for 1,333 keV gamma rays in a drift field of 200 V/cm). Liquid xenon time projection chambers with such high energy resolution may find applications not only in dark matter direct detection searches, but also in neutrinoless double beta decay experiments and other applications.

Small scale H I structure and the soft X-ray background

NASA Technical Reports Server (NTRS)

Jahoda, K.; Mccammon, D.; Lockman, F. J.

1986-01-01

The observed anticorrelation between diffuse soft X-ray flux and H I column density has been explained as absorption of soft X-rays produced in a hot galactic halo, assuming that the neutral interstellar material is sufficiently clumped to reduce the soft X-ray absorption cross section by a factor of two to three. A 21 cm emission line study of H I column density variations at intermediate and high galactic latitudes to 10' spatial resolution has been done. The results confirm conclusions from preliminary work at coarser resolution, and in combination with other data appear to rule out the hypothesis that clumping of neutral interstellar matter on any angular scale significantly reduces X-ray absorption cross sections in the 0.13 - 0.28 keV energy range. It is concluded therefore that the observed anticorrelation is not primarily a consequence of absorption of soft X-rays produced in a hot galactic halo.