Efficient super-resolution image reconstruction applied to surveillance video captured by small unmanned aircraft systems

NASA Astrophysics Data System (ADS)

He, Qiang; Schultz, Richard R.; Chu, Chee-Hung Henry

2008-04-01

The concept surrounding super-resolution image reconstruction is to recover a highly-resolved image from a series of low-resolution images via between-frame subpixel image registration. In this paper, we propose a novel and efficient super-resolution algorithm, and then apply it to the reconstruction of real video data captured by a small Unmanned Aircraft System (UAS). Small UAS aircraft generally have a wingspan of less than four meters, so that these vehicles and their payloads can be buffeted by even light winds, resulting in potentially unstable video. This algorithm is based on a coarse-to-fine strategy, in which a coarsely super-resolved image sequence is first built from the original video data by image registration and bi-cubic interpolation between a fixed reference frame and every additional frame. It is well known that the median filter is robust to outliers. If we calculate pixel-wise medians in the coarsely super-resolved image sequence, we can restore a refined super-resolved image. The primary advantage is that this is a noniterative algorithm, unlike traditional approaches based on highly-computational iterative algorithms. Experimental results show that our coarse-to-fine super-resolution algorithm is not only robust, but also very efficient. In comparison with five well-known super-resolution algorithms, namely the robust super-resolution algorithm, bi-cubic interpolation, projection onto convex sets (POCS), the Papoulis-Gerchberg algorithm, and the iterated back projection algorithm, our proposed algorithm gives both strong efficiency and robustness, as well as good visual performance. This is particularly useful for the application of super-resolution to UAS surveillance video, where real-time processing is highly desired.

Efficient high-resolution hard x-ray imaging with transparent Lu2O3:Eu scintillator thin films

NASA Astrophysics Data System (ADS)

Marton, Zsolt; Miller, Stuart R.; Brecher, Charles; Kenesei, Peter; Moore, Matthew D.; Woods, Russell; Almer, Jonathan D.; Miceli, Antonino; Nagarkar, Vivek V.

2015-09-01

We have developed microstructured Lu2O3:Eu scintillator films that provide spatial resolution on the order of micrometers for hard X-ray imaging. In addition to their outstanding resolution, Lu2O3:Eu films also exhibits both high absorption efficiency for 20 to 100 keV X-rays, and bright 610 nm emission whose intensity rivals that of the brightest known scintillators. At present, high spatial resolution of such a magnitude is achieved using ultra-thin scintillators measuring only about 1 to 5 μm in thickness, which limits absorption efficiency to ~3% for 12 keV X-rays and less than 0.1% for 20 to 100 keV X-rays; this results in excessive measurement time and exposure to the specimen. But the absorption efficiency of Lu2O3:Eu (99.9% @12 keV and 30% @ 70 keV) is much greater, significantly decreasing measurement time and radiation exposure. Our Lu2O3:Eu scintillator material, fabricated by our electron-beam physical vapor deposition (EB-PVD) process, combines superior density of 9.5 g/cm3, a microcolumnar structure for higher spatial resolution, and a bright emission (48000 photons/MeV) whose wavelength is an ideal match for the underlying CCD detector array. We grew thin films of this material on a variety of matching substrates, measuring some 5-10μm in thickness and covering areas up to 1 x 1 cm2, which can be a suitable basis for microtomography, digital radiography as well as CT and hard X-ray Micro-Tomography (XMT). The microstructure and optical transparency of such screens was optimized, and their imaging performance was evaluated in the Argonne National Laboratory's Advanced Photon Source. Spatial resolution and efficiency were also characterized.

Efficient parallel reconstruction for high resolution multishot spiral diffusion data with low rank constraint.

PubMed

Liao, Congyu; Chen, Ying; Cao, Xiaozhi; Chen, Song; He, Hongjian; Mani, Merry; Jacob, Mathews; Magnotta, Vincent; Zhong, Jianhui

2017-03-01

To propose a novel reconstruction method using parallel imaging with low rank constraint to accelerate high resolution multishot spiral diffusion imaging. The undersampled high resolution diffusion data were reconstructed based on a low rank (LR) constraint using similarities between the data of different interleaves from a multishot spiral acquisition. The self-navigated phase compensation using the low resolution phase data in the center of k-space was applied to correct shot-to-shot phase variations induced by motion artifacts. The low rank reconstruction was combined with sensitivity encoding (SENSE) for further acceleration. The efficiency of the proposed joint reconstruction framework, dubbed LR-SENSE, was evaluated through error quantifications and compared with ℓ1 regularized compressed sensing method and conventional iterative SENSE method using the same datasets. It was shown that with a same acceleration factor, the proposed LR-SENSE method had the smallest normalized sum-of-squares errors among all the compared methods in all diffusion weighted images and DTI-derived index maps, when evaluated with different acceleration factors (R = 2, 3, 4) and for all the acquired diffusion directions. Robust high resolution diffusion weighted image can be efficiently reconstructed from highly undersampled multishot spiral data with the proposed LR-SENSE method. Magn Reson Med 77:1359-1366, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

A generic framework for internet-based interactive applications of high-resolution 3-D medical image data.

PubMed

Liu, Danzhou; Hua, Kien A; Sugaya, Kiminobu

2008-09-01

With the advances in medical imaging devices, large volumes of high-resolution 3-D medical image data have been produced. These high-resolution 3-D data are very large in size, and severely stress storage systems and networks. Most existing Internet-based 3-D medical image interactive applications therefore deal with only low- or medium-resolution image data. While it is possible to download the whole 3-D high-resolution image data from the server and perform the image visualization and analysis at the client site, such an alternative is infeasible when the high-resolution data are very large, and many users concurrently access the server. In this paper, we propose a novel framework for Internet-based interactive applications of high-resolution 3-D medical image data. Specifically, we first partition the whole 3-D data into buckets, remove the duplicate buckets, and then, compress each bucket separately. We also propose an index structure for these buckets to efficiently support typical queries such as 3-D slicer and region of interest, and only the relevant buckets are transmitted instead of the whole high-resolution 3-D medical image data. Furthermore, in order to better support concurrent accesses and to improve the average response time, we also propose techniques for efficient query processing, incremental transmission, and client sharing. Our experimental study in simulated and realistic environments indicates that the proposed framework can significantly reduce storage and communication requirements, and can enable real-time interaction with remote high-resolution 3-D medical image data for many concurrent users.

Low-dose, high-resolution and high-efficiency ptychography at STXM beamline of SSRF

NASA Astrophysics Data System (ADS)

Xu, Zijian; Wang, Chunpeng; Liu, Haigang; Tao, Xulei; Tai, Renzhong

2017-06-01

Ptychography is a diffraction-based X-ray microscopy method that can image extended samples quantitatively while remove the resolution limit imposed by image-forming optical elements. As a natural extension of scanning transmission X-ray microscopy (STXM) imaging method, we developed soft X-ray ptychographic coherent diffraction imaging (PCDI) method at the STXM endstation of BL08U beamline of Shanghai Synchrotron Radiation Facility. Compared to the traditional STXM imaging, the new PCDI method has resulted in significantly lower dose, higher resolution and higher efficiency imaging in our platform. In the demonstration experiments shown here, a spatial resolution of sub-10 nm was obtained for a gold nanowires sample, which is much better than the limit resolution 30 nm of the STXM method, while the radiation dose is only 1/12 of STXM.

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.

Production of radially and azimuthally polarized polychromatic beams

NASA Astrophysics Data System (ADS)

Shoham, A.; Vander, R.; Lipson, S. G.

2006-12-01

We describe a system that efficiently provides radially or azimuthally polarized radiation from a randomly polarized source. It is constructed from two conical reflectors and a cylindrical sheet of polarizing film. Envisaged applications include a microscope illuminator for high-resolution surface plasmon resonance microscopy, illumination for high-resolution microlithography, and efficient coupling of a laser source to hollow optical fibers. The angular coherence function of light polarized by the device was measured to evaluate its usefulness for these applications.

In-line FINCH super resolution digital holographic fluorescence microscopy using a high efficiency transmission liquid crystal GRIN lens.

PubMed

Brooker, Gary; Siegel, Nisan; Rosen, Joseph; Hashimoto, Nobuyuki; Kurihara, Makoto; Tanabe, Ayano

2013-12-15

We report a new optical arrangement that creates high-efficiency, high-quality Fresnel incoherent correlation holography (FINCH) holograms using polarization sensitive transmission liquid crystal gradient index (TLCGRIN) diffractive lenses. In contrast, current universal practice in the field employs a reflective spatial light modulator (SLM) to separate sample and reference beams. Polarization sensitive TLCGRIN lenses enable a straight optical path, have >90% transmission efficiency, are not pixilated, and are free of many limitations of reflective SLM devices. For each sample point, two spherical beams created by a glass lens in combination with a polarization sensitive TLCGRIN lens interfere and create a hologram and resultant super resolution image.

High resolution time-to-space conversion of sub-picosecond pulses at 1.55µm by non-degenerate SFG in PPLN crystal.

PubMed

Shayovitz, Dror; Herrmann, Harald; Sohler, Wolfgang; Ricken, Raimund; Silberhorn, Christine; Marom, Dan M

2012-11-19

We demonstrate high resolution and increased efficiency background-free time-to-space conversion using spectrally resolved non-degenerate and collinear SFG in a bulk PPLN crystal. A serial-to-parallel resolution factor of 95 and a time window of 42 ps were achieved. A 60-fold increase in conversion efficiency slope compared with our previous work using a BBO crystal [D. Shayovitz and D. M. Marom, Opt. Lett. 36, 1957 (2011)] was recorded. Finally the measured 40 GHz narrow linewidth of the output SFG signal implies the possibility to extract phase information by employing coherent detection techniques.

CZT drift strip detectors for high energy astrophysics

NASA Astrophysics Data System (ADS)

Kuvvetli, I.; Budtz-Jørgensen, C.; Caroli, E.; Auricchio, N.

2010-12-01

Requirements for X- and gamma ray detectors for future High Energy Astrophysics missions include high detection efficiency and good energy resolution as well as fine position sensitivity even in three dimensions. We report on experimental investigations on the CZT drift detector developed DTU Space. It is operated in the planar transverse field (PTF) mode, with the purpose of demonstrating that the good energy resolution of the CZT drift detector can be combined with the high efficiency of the PTF configuration. Furthermore, we demonstrated and characterized the 3D sensing capabilities of this detector configuration. The CZT drift strip detector (10 mm×10 mm×2.5 mm) was characterized in both standard illumination geometry, Photon Parallel Field (PPF) configuration and in PTF configuration. The detection efficiency and energy resolution are compared for both configurations . The PTF configuration provided a higher efficiency in agreement with calculations. The detector energy resolution was found to be the same (3 keV FWHM at 122 keV) in both in PPF and PTF . The depth sensing capabilities offered by drift strip detectors was investigated by illuminating the detector using a collimated photon beam of 57Co radiation in PTF configuration. The width (300μm FWHM at 122 keV) of the measured depth distributions was almost equal to the finite beam size. However, the data indicate that the best achievable depth resolution for the CZT drift detector is 90μm FWHM at 122 keV and that it is determined by the electronic noise from the setup.

Chemical speciation using high energy resolution PIXE spectroscopy in the tender X-ray range

NASA Astrophysics Data System (ADS)

Kavčič, Matjaž; Petric, Marko; Vogel-Mikuš, Katarina

2018-02-01

High energy resolution X-ray emission spectroscopy employing wavelength dispersive (WDS) crystal spectrometers can provide energy resolution on the level of core-hole lifetime broadening of the characteristic emission lines. While crystal spectrometers have been traditionally used in combination with electron excitation for major and minor element analysis, they have been rarely considered in proton induced X-ray emission (PIXE) trace element analysis mainly due to low detection efficiency. Compared to the simplest flat crystal WDS spectrometer the efficiency can be improved by employing cylindrically or even spherically curved crystals in combination with position sensitive X-ray detectors. When such spectrometer is coupled to MeV proton excitation, chemical bonding effects are revealed in the high energy resolution spectra yielding opportunity to extend the analytical capabilities of PIXE technique also towards chemical state analysis. In this contribution we will focus on the high energy resolution PIXE (HR-PIXE) spectroscopy in the tender X-ray range performed in our laboratory with our home-built tender X-ray emission spectrometer. Some general properties of high energy resolution PIXE spectroscopy in the tender X-ray range are presented followed by an example of sulfur speciation in biological tissue illustrating the capabilities as well as limitations of HR-PIXE method used for chemical speciation in the tender X-ray range.

Performance characterization of high quantum efficiency metal package photomultiplier tubes for time-of-flight and high-resolution PET applications.

PubMed

Ko, Guen Bae; Lee, Jae Sung

2015-01-01

Metal package photomultiplier tubes (PMTs) with a metal channel dynode structure have several advanced features for devising such time-of-flight (TOF) and high spatial resolution positron emission tomography (PET) detectors, thanks to their high packing density, large effective area ratio, fast time response, and position encoding capability. Here, we report on an investigation of new metal package PMTs with high quantum efficiency (QE) for high-resolution PET and TOF PET detector modules. The latest metal package PMT, the Hamamatsu R11265 series, is served with two kinds of photocathodes that have higher quantum efficiency than normal bialkali (typical QE ≈ 25%), super bialkali (SBA; QE ≈ 35%), and ultra bialkali (UBA; QE ≈ 43%). In this study, the authors evaluated the performance of the new PMTs with SBA and UBA photocathodes as a PET detector by coupling various crystal arrays. They also investigated the performance improvements of high QE, focusing in particular on a block detector coupled with a lutetium-based scintillator. A single 4 × 4 × 10 mm(3) LYSO, a 7 × 7 array of 3 × 3 × 20 mm(3) LGSO, a 9 × 9 array of 1.2 × 1.2 × 10 mm(3) LYSO, and a 6 × 6 array of 1.5 × 1.5 × 7 mm(3) LuYAP were used for evaluation. All coincidence data were acquired with a DRS4 based fast digitizer. This new PMT shows promising crystal positioning accuracy, energy and time discrimination performance for TOF, and high-resolution PET applications. The authors also found that a metal channel PMT with SBA was enough for both TOF and high-resolution application, although UBA gave a minor improvement to time resolution. However, significant performance improvement was observed in relative low light output crystals (LuYAP) coupled with UBA. The results of this study will be of value as a useful reference to select PMTs for high-performance PET detectors.

High-Resolution and -Efficiency Gamma-Ray Detection for the FRIB Decay Station

NASA Astrophysics Data System (ADS)

Grover, Hannah; Leach, Kyle; Natzke, Connor; FRIB Decay Station Collaboration Collaboration

2017-09-01

As we push our knowledge of nuclear structure to the frontier of the unknown with FRIB, a new high-efficiency, -resolution, and -sensitivity photon-detection device is critical. The FRIB Decay Station Collaboration is working to create a new detector array that meets the needs of the exploratory nature of FRIB by minimizing cost and maximizing efficiency. GEANT4 simulations are being utilized to combine detectors in various configurations to test their feasibility. I will discuss these simulations and how they compare to existing simulations of past-generation decay-spectroscopy equipment. This work has been funded by the DOE Office of Science, Office of Nuclear Physics.

Towards high-resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion

PubMed Central

Ferrer, R.; Barzakh, A.; Bastin, B.; Beerwerth, R.; Block, M.; Creemers, P.; Grawe, H.; de Groote, R.; Delahaye, P.; Fléchard, X.; Franchoo, S.; Fritzsche, S.; Gaffney, L. P.; Ghys, L.; Gins, W.; Granados, C.; Heinke, R.; Hijazi, L.; Huyse, M.; Kron, T.; Kudryavtsev, Yu.; Laatiaoui, M.; Lecesne, N.; Loiselet, M.; Lutton, F.; Moore, I. D.; Martínez, Y.; Mogilevskiy, E.; Naubereit, P.; Piot, J.; Raeder, S.; Rothe, S.; Savajols, H.; Sels, S.; Sonnenschein, V.; Thomas, J-C; Traykov, E.; Van Beveren, C.; Van den Bergh, P.; Van Duppen, P.; Wendt, K.; Zadvornaya, A.

2017-01-01

Resonant laser ionization and spectroscopy are widely used techniques at radioactive ion beam facilities to produce pure beams of exotic nuclei and measure the shape, size, spin and electromagnetic multipole moments of these nuclei. However, in such measurements it is difficult to combine a high efficiency with a high spectral resolution. Here we demonstrate the on-line application of atomic laser ionization spectroscopy in a supersonic gas jet, a technique suited for high-precision studies of the ground- and isomeric-state properties of nuclei located at the extremes of stability. The technique is characterized in a measurement on actinium isotopes around the N=126 neutron shell closure. A significant improvement in the spectral resolution by more than one order of magnitude is achieved in these experiments without loss in efficiency. PMID:28224987

Trajectory Segmentation Map-Matching Approach for Large-Scale, High-Resolution GPS Data

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

Zhu, Lei; Holden, Jacob R.; Gonder, Jeffrey D.

With the development of smartphones and portable GPS devices, large-scale, high-resolution GPS data can be collected. Map matching is a critical step in studying vehicle driving activity and recognizing network traffic conditions from the data. A new trajectory segmentation map-matching algorithm is proposed to deal accurately and efficiently with large-scale, high-resolution GPS trajectory data. The new algorithm separated the GPS trajectory into segments. It found the shortest path for each segment in a scientific manner and ultimately generated a best-matched path for the entire trajectory. The similarity of a trajectory segment and its matched path is described by a similaritymore » score system based on the longest common subsequence. The numerical experiment indicated that the proposed map-matching algorithm was very promising in relation to accuracy and computational efficiency. Large-scale data set applications verified that the proposed method is robust and capable of dealing with real-world, large-scale GPS data in a computationally efficient and accurate manner.« less

Trajectory Segmentation Map-Matching Approach for Large-Scale, High-Resolution GPS Data

DOE PAGES

Zhu, Lei; Holden, Jacob R.; Gonder, Jeffrey D.

2017-01-01

With the development of smartphones and portable GPS devices, large-scale, high-resolution GPS data can be collected. Map matching is a critical step in studying vehicle driving activity and recognizing network traffic conditions from the data. A new trajectory segmentation map-matching algorithm is proposed to deal accurately and efficiently with large-scale, high-resolution GPS trajectory data. The new algorithm separated the GPS trajectory into segments. It found the shortest path for each segment in a scientific manner and ultimately generated a best-matched path for the entire trajectory. The similarity of a trajectory segment and its matched path is described by a similaritymore » score system based on the longest common subsequence. The numerical experiment indicated that the proposed map-matching algorithm was very promising in relation to accuracy and computational efficiency. Large-scale data set applications verified that the proposed method is robust and capable of dealing with real-world, large-scale GPS data in a computationally efficient and accurate manner.« less

Dynamic frame resizing with convolutional neural network for efficient video compression

NASA Astrophysics Data System (ADS)

Kim, Jaehwan; Park, Youngo; Choi, Kwang Pyo; Lee, JongSeok; Jeon, Sunyoung; Park, JeongHoon

2017-09-01

In the past, video codecs such as vc-1 and H.263 used a technique to encode reduced-resolution video and restore original resolution from the decoder for improvement of coding efficiency. The techniques of vc-1 and H.263 Annex Q are called dynamic frame resizing and reduced-resolution update mode, respectively. However, these techniques have not been widely used due to limited performance improvements that operate well only under specific conditions. In this paper, video frame resizing (reduced/restore) technique based on machine learning is proposed for improvement of coding efficiency. The proposed method features video of low resolution made by convolutional neural network (CNN) in encoder and reconstruction of original resolution using CNN in decoder. The proposed method shows improved subjective performance over all the high resolution videos which are dominantly consumed recently. In order to assess subjective quality of the proposed method, Video Multi-method Assessment Fusion (VMAF) which showed high reliability among many subjective measurement tools was used as subjective metric. Moreover, to assess general performance, diverse bitrates are tested. Experimental results showed that BD-rate based on VMAF was improved by about 51% compare to conventional HEVC. Especially, VMAF values were significantly improved in low bitrate. Also, when the method is subjectively tested, it had better subjective visual quality in similar bit rate.

Efficiency calibration of the first multilayer-coated holographic ion-etched flight grating for a sounding rocket high-resolution spectrometer.

PubMed

Kowalski, M P; Barbee, T W; Heidemann, K F; Gursky, H; Rife, J C; Hunter, W R; Fritz, G G; Cruddace, R G

1999-11-01

We have fabricated the four flight gratings for a sounding rocket high-resolution spectrometer using a holographic ion-etching technique. The gratings are spherical (4000-mm radius of curvature), large (160 mm x 90 mm), and have a laminar groove profile of high density (3600 grooves/mm). They have been coated with a high-reflectance multilayer of Mo/Si. Using an atomic force microscope, we examined the surface characteristics of the first grating before and after multilayer coating. The average roughness is approximately 3 A rms after coating. Using synchrotron radiation, we completed an efficiency calibration map over the wavelength range 225-245 A. At an angle of incidence of 5 degrees and a wavelength of 234 A, the average efficiency in the first inside order is 10.4 +/- 0.5%, and the derived groove efficiency is 34.8 +/- 1.6%. These values exceed all previously published results for a high-density grating.

Convergence and divergence across construction methods for human brain white matter networks: an assessment based on individual differences.

PubMed

Zhong, Suyu; He, Yong; Gong, Gaolang

2015-05-01

Using diffusion MRI, a number of studies have investigated the properties of whole-brain white matter (WM) networks with differing network construction methods (node/edge definition). However, how the construction methods affect individual differences of WM networks and, particularly, if distinct methods can provide convergent or divergent patterns of individual differences remain largely unknown. Here, we applied 10 frequently used methods to construct whole-brain WM networks in a healthy young adult population (57 subjects), which involves two node definitions (low-resolution and high-resolution) and five edge definitions (binary, FA weighted, fiber-density weighted, length-corrected fiber-density weighted, and connectivity-probability weighted). For these WM networks, individual differences were systematically analyzed in three network aspects: (1) a spatial pattern of WM connections, (2) a spatial pattern of nodal efficiency, and (3) network global and local efficiencies. Intriguingly, we found that some of the network construction methods converged in terms of individual difference patterns, but diverged with other methods. Furthermore, the convergence/divergence between methods differed among network properties that were adopted to assess individual differences. Particularly, high-resolution WM networks with differing edge definitions showed convergent individual differences in the spatial pattern of both WM connections and nodal efficiency. For the network global and local efficiencies, low-resolution and high-resolution WM networks for most edge definitions consistently exhibited a highly convergent pattern in individual differences. Finally, the test-retest analysis revealed a decent temporal reproducibility for the patterns of between-method convergence/divergence. Together, the results of the present study demonstrated a measure-dependent effect of network construction methods on the individual difference of WM network properties. © 2015 Wiley Periodicals, Inc.

High resolution CsI(Tl)/Si-PIN detector development for breast imaging

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

Patt, B.E.; Iwanczyk, J.S.; Tull, C.R.

High resolution multi-element (8x8) imaging arrays with collimators, size matched to discrete CsI(Tl) scintillator arrays and Si-PIN photodetector arrays (PDA`s) were developed as prototypes for larger arrays for breast imaging. Photodetector pixels were each 1.5 {times} 1.5 mm{sup 2} with 0.25 mm gaps. A 16-element quadrant of the detector was evaluated with a segmented CsI(Tl) scintillator array coupled to the silicon array. The scintillator thickness of 6 mm corresponds to >85% total gamma efficiency at 140 keV. Pixel energy resolution of <8% FWHM was obtained for Tc-99m. Electronic noise was 41 e{sup {minus}} RMS corresponding to a 3% FWHM contributionmore » to the 140 keV photopeak. Detection efficiency uniformity measured with a Tc-99m flood source was 4.3% for an {approximately}10% energy photopeak window. Spatial resolution was 1.53 mm FWHM and pitch was 1.75 mm as measured from the Co-57 (122 keV) line spread function. Signal to background was 34 and contrast was 0.94. The energy resolution and spatial characteristics of the new imaging detector exceed those of other scintillator based imaging detectors. A camera based on this technology will allow: (1) Improved Compton scatter rejection; (2) Detector positioning in close proximity to the breast to increase signal to noise; (3) Improved spatial resolution; and (4) Improved efficiency compared to high resolution collimated gamma cameras for the anticipated compressed breast geometries.« less

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.

More are better, but the details matter: combinations of multiple Fresnel zone plates for improved resolution and efficiency in X-ray microscopy

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

Li, Kenan; Jacobsen, Chris

Fresnel zone plates used for X-ray nanofocusing face high-aspect-ratio nanofabrication challenges in combining narrow transverse features (for high spatial resolution) along with extended optical modulation along the X-ray beam direction (to improve efficiency). The stacking of multiple Fresnel zone plates along the beam direction has already been shown to offer improved characteristics of resolution and efficiency when compared with thin single zone plates. Using multislice wave propagation simulation methods, here a number of new schemes for the stacking of multiple Fresnel zone plates are considered. These include consideration of optimal thickness and spacing in the axial direction, and methods tomore » capture a fraction of the light otherwise diffracted into unwanted orders, and instead bring it into the desired first-order focus. In conclusion, the alignment tolerances for stacking multiple Fresnel zone plates are also considered.« less

Efficient random access high resolution region-of-interest (ROI) image retrieval using backward coding of wavelet trees (BCWT)

NASA Astrophysics Data System (ADS)

Corona, Enrique; Nutter, Brian; Mitra, Sunanda; Guo, Jiangling; Karp, Tanja

2008-03-01

Efficient retrieval of high quality Regions-Of-Interest (ROI) from high resolution medical images is essential for reliable interpretation and accurate diagnosis. Random access to high quality ROI from codestreams is becoming an essential feature in many still image compression applications, particularly in viewing diseased areas from large medical images. This feature is easier to implement in block based codecs because of the inherent spatial independency of the code blocks. This independency implies that the decoding order of the blocks is unimportant as long as the position for each is properly identified. In contrast, wavelet-tree based codecs naturally use some interdependency that exploits the decaying spectrum model of the wavelet coefficients. Thus one must keep track of the decoding order from level to level with such codecs. We have developed an innovative multi-rate image subband coding scheme using "Backward Coding of Wavelet Trees (BCWT)" which is fast, memory efficient, and resolution scalable. It offers far less complexity than many other existing codecs including both, wavelet-tree, and block based algorithms. The ROI feature in BCWT is implemented through a transcoder stage that generates a new BCWT codestream containing only the information associated with the user-defined ROI. This paper presents an efficient technique that locates a particular ROI within the BCWT coded domain, and decodes it back to the spatial domain. This technique allows better access and proper identification of pathologies in high resolution images since only a small fraction of the codestream is required to be transmitted and analyzed.

All-fiber probe for optical coherence tomography with an extended depth of focus by a high-efficient fiber-based filter

NASA Astrophysics Data System (ADS)

Qiu, Jianrong; Shen, Yi; Shangguan, Ziwei; Bao, Wen; Yang, Shanshan; Li, Peng; Ding, Zhihua

2018-04-01

Although methods have been proposed to maintain high transverse resolution over an increased depth range, it is not straightforward to scale down the bulk-optic solutions to minimized probes of optical coherence tomography (OCT). In this paper, we propose a high-efficient fiber-based filter in an all-fiber OCT probe to realize an extended depth of focus (DOF) while maintaining a high transverse resolution. Mode interference in the probe is exploited to modulate the complex field with controllable radial distribution. The principle of DOF extension by the fiber-based filter is theoretically analyzed. Numerical simulations are conducted to evaluate the performances of the designed probes. A DOF extension ratio of 2.6 over conventional Gaussian beam is obtainable in one proposed probe under a focused beam diameter of 4 . 6 μm. Coupling efficiencies of internal interfaces of the proposed probe are below -40 dB except the last probe-air interface, which can also be depressed to be -44 dB after minor modification in lengths for the filter. Length tolerance of the proposed probe is determined to be - 28 / + 20 μm, which is readily satisfied in fabrication. With the merits of extended-DOF, high-resolution, high-efficiency and easy-fabrication, the proposed probe is promising in endoscopic applications.

Crystallization-induced dynamic resolution of Fox chiral auxiliary and application to the diastereoselective electrophilic fluorination of amide enolates.

PubMed

Lubin, Hodney; Dupuis, Christophe; Pytkowicz, Julien; Brigaud, Thierry

2013-04-05

A highly efficient crystallization-induced dynamic resolution (CIDR) of trans-Fox (fluorinated oxazolidine) chiral auxiliary is reported. This chiral auxiliary was used for highly diastereoselective (>98% de) electrophilic fluorination of amide enolates. After removal of the chiral auxiliary, highly valuable enantiopure α-fluorocarboxylic acids and β-fluoroalcohols are obtained.

Extreme ultraviolet performance of a multilayer coated high density toroidal grating

NASA Technical Reports Server (NTRS)

Thomas, Roger J.; Keski-Kuha, Ritva A. M.; Neupert, Werner M.; Condor, Charles E.; Gum, Jeffrey S.

1991-01-01

The performance of a multilayer coated diffraction grating has been evaluated at EUV wavelengths both in terms of absolute efficiency and spectral resolution. The application of ten-layer Ir/Si multilayer coating to a 3600-lines/mm blazed toroidal replica grating produced a factor of 9 enhancement in peak efficiency near the design wavelength of about 30 nm in first order, without degrading its excellent quasistigmatic spectral resolution. The measured EUV efficiency peaked at 3.3 percent and was improved over the full spectral range between 25 and 35 nm compared with the premultilayer replica which had a standard gold coating. In addition, the grating's spectral resolution of greater than 5000 was maintained.

High resolution, high frame rate video technology development plan and the near-term system conceptual design

NASA Technical Reports Server (NTRS)

Ziemke, Robert A.

1990-01-01

The objective of the High Resolution, High Frame Rate Video Technology (HHVT) development effort is to provide technology advancements to remove constraints on the amount of high speed, detailed optical data recorded and transmitted for microgravity science and application experiments. These advancements will enable the development of video systems capable of high resolution, high frame rate video data recording, processing, and transmission. Techniques such as multichannel image scan, video parameter tradeoff, and the use of dual recording media were identified as methods of making the most efficient use of the near-term technology.

Microfabrication of High Resolution X-ray Magnetic Calorimeters

NASA Astrophysics Data System (ADS)

Hsieh, Wen-Ting; Bandler, Simon R.; Kelly, Daniel P.; Porst, Jan P.; Rotzinger, Hannes; Seidel, George M.; Stevenson, Thomas R.

2009-12-01

Metallic magnetic calorimeter (MMC) is one of the most promising x-ray detector technologies for providing the very high energy resolution needed for future astronomical x-ray imaging spectroscopy. For this purpose, we have developed micro-fabricated 5×5 arrays of MMC of which each individual pixel has excellent energy resolution as good as 3.4 eV at 6 keV x-ray. Here we report on the fabrication techniques developed to achieve good resolution and high efficiency. These include: processing of a thin insulation layer for strong magnetic coupling between the AuEr sensor film and the niobium pick-up coil; production of overhanging absorbers for enhanced efficiency of x-ray absorption; fabrication on SiN membranes to minimize the effects on energy resolution from athermal phonon loss. We have also improved the deposition of the magnetic sensor film such that the film magnetization is nearly completely that is expected from the AuEr sputter target bulk material. In addition, we have included a study of a positional sensitive design, the Hydra design, which allows thermal coupling of four absorbers to a common MMC sensor and circuit.

Innovative diffraction gratings for high-resolution resonant inelastic soft x-ray scattering spectroscopy

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

Voronov, D.L.; Warwick, T.; Gullikson, E. M.

2016-07-27

High-resolution Resonant Inelastic X-ray Scattering (RIXS) requires diffraction gratings with very exacting characteristics. The gratings should provide both very high dispersion and high efficiency which are conflicting requirements and extremely challenging to satisfy in the soft x-ray region for a traditional grazing incidence geometry. To achieve high dispersion one should increase the groove density of a grating; this however results in a diffraction angle beyond the critical angle range and results in drastic efficiency loss. The problem can be solved by use of multilayer coated blazed gratings (MBG). In this work we have investigated the diffraction characteristics of MBGs viamore » numerical simulations and have developed a procedure for optimization of grating design for a multiplexed high resolution imaging spectrometer for RIXS spectroscopy to be built in sector 6 at the Advanced Light Source (ALS). We found that highest diffraction efficiency can be achieved for gratings optimized for 4{sup th} or 5{sup th} order operation. Fabrication of such gratings is an extremely challenging technological problem. We present a first experimental prototype of these gratings and report its performance. High order and high line density gratings have the potential to be a revolutionary new optical element that should have great impact in the area of soft x-ray RIXS.« less

Spatial resolution limitation of liquid crystal spatial light modulator

NASA Astrophysics Data System (ADS)

Wang, Xinghua; Wang, Bin; McManamon, Paul F., III; Pouch, John J.; Miranda, Felix A.; Anderson, James E.; Bos, Philip J.

2004-10-01

The effect of fringing electric fields in a liquid crystal (LC) Optical Phased Array (OPA), also referred to as a spatial light modulator (SLM), is a governing factor that determines the diffraction efficiency (DE) of the LC OPA for high resolution spatial phase modulation. In this article, the fringing field effect in a high resolution LC OPA is studied by accurate modeling the DE of the LC blazed gratings by LC director simulation and Finite Difference Time Domain (FDTD) simulation. Influence factors that contribute significantly to the DE are discussed. Such results provide fundamental understanding for high resolution LC devices.

Incorporation of ionic liquid into porous polymer monoliths to enhance the separation of small molecules in reversed-phase high-performance liquid chromatography.

PubMed

Wang, Jiafei; Bai, Ligai; Wei, Zhen; Qin, Junxiao; Ma, Yamin; Liu, Haiyan

2015-06-01

An ionic liquid was incorporated into the porous polymer monoliths to afford stationary phases with enhanced chromatographic performance for small molecules in reversed-phase high-performance liquid chromatography. The effect of the ionic liquid in the polymerization mixture on the performance of the monoliths was studied in detail. While monoliths without ionic liquid exhibited poor resolution and low efficiency, the addition of ionic liquid to the polymerization mixture provides highly increased resolution and high efficiency. The chromatographic performances of the monoliths were demonstrated by the separations of various small molecules including aromatic hydrocarbons, isomers, and homologues using a binary polar mobile phase. The present column efficiency reached 27 000 plates/m, which showed that the ionic liquid monoliths are alternative stationary phases in the separation of small molecules by high-performance liquid chromatography. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study on High Resolution Membrane-Based Diffractive Optical Imaging on Geostationary Orbit

NASA Astrophysics Data System (ADS)

Jiao, J.; Wang, B.; Wang, C.; Zhang, Y.; Jin, J.; Liu, Z.; Su, Y.; Ruan, N.

2017-05-01

Diffractive optical imaging technology provides a new way to realize high resolution earth observation on geostationary orbit. There are a lot of benefits to use the membrane-based diffractive optical element in ultra-large aperture optical imaging system, including loose tolerance, light weight, easy folding and unfolding, which make it easy to realize high resolution earth observation on geostationary orbit. The implementation of this technology also faces some challenges, including the configuration of the diffractive primary lens, the development of high diffraction efficiency membrane-based diffractive optical elements, and the correction of the chromatic aberration of the diffractive optical elements. Aiming at the configuration of the diffractive primary lens, the "6+1" petal-type unfold scheme is proposed, which consider the compression ratio, the blocking rate and the development complexity. For high diffraction efficiency membrane-based diffractive optical element, a self-collimating method is proposed. The diffraction efficiency is more than 90 % of the theoretical value. For the chromatic aberration correction problem, an optimization method based on schupmann is proposed to make the imaging spectral bandwidth in visible light band reach 100 nm. The above conclusions have reference significance for the development of ultra-large aperture diffractive optical imaging system.

Facile room-temperature solution-phase synthesis of a spherical covalent organic framework for high-resolution chromatographic separation.

PubMed

Yang, Cheng-Xiong; Liu, Chang; Cao, Yi-Meng; Yan, Xiu-Ping

2015-08-07

A simple and facile room-temperature solution-phase synthesis was developed to fabricate a spherical covalent organic framework with large surface area, good solvent stability and high thermostability for high-resolution chromatographic separation of diverse important industrial analytes including alkanes, cyclohexane and benzene, α-pinene and β-pinene, and alcohols with high column efficiency and good precision.

High resolution, two-dimensional imaging, microchannel plate detector for use on a sounding rocket experiment

NASA Technical Reports Server (NTRS)

Bush, Brett C.; Cotton, Daniel M.; Siegmund, Oswald H.; Chakrabarti, Supriya; Harris, Walter; Clarke, John

1991-01-01

We discuss a high resolution microchannel plate (MCP) imaging detector to be used in measurements of Doppler-shifted hydrogen Lyman-alpha line emission from Jupiter and the interplanetary medium. The detector is housed in a vacuum-tight stainless steel cylinder (to provide shielding from magnetic fields) with a MgF2 window. Operating at nominal voltage, the four plate configuration provides a gain of 1.2 x 10 exp 7 electrons per incident photon. The wedge-and-strip anode has two-dimensional imaging capabilities, with a resolution of 40 microns FWHM over a one centimeter diameter area. The detector has a high quantum efficiency while retaining a low background rate. A KBr photocathode is used to enhance the quantum efficiency of the bare MCPs to a value of 35 percent at Lyman-alpha.

Efficient Approaches for Propagating Hydrologic Forcing Uncertainty: High-Resolution Applications Over the Western United States

NASA Astrophysics Data System (ADS)

Hobbs, J.; Turmon, M.; David, C. H.; Reager, J. T., II; Famiglietti, J. S.

2017-12-01

NASA's Western States Water Mission (WSWM) combines remote sensing of the terrestrial water cycle with hydrological models to provide high-resolution state estimates for multiple variables. The effort includes both land surface and river routing models that are subject to several sources of uncertainty, including errors in the model forcing and model structural uncertainty. Computational and storage constraints prohibit extensive ensemble simulations, so this work outlines efficient but flexible approaches for estimating and reporting uncertainty. Calibrated by remote sensing and in situ data where available, we illustrate the application of these techniques in producing state estimates with associated uncertainties at kilometer-scale resolution for key variables such as soil moisture, groundwater, and streamflow.

Surface Desorption Dielectric-Barrier Discharge Ionization Mass Spectrometry.

PubMed

Zhang, Hong; Jiang, Jie; Li, Na; Li, Ming; Wang, Yingying; He, Jing; You, Hong

2017-07-18

A variant of dielectric-barrier discharge named surface desorption dielectric-barrier discharge ionization (SDDBDI) mass spectrometry was developed for high-efficiency ion transmission and high spatial resolution imaging. In SDDBDI, a tungsten nanotip and the inlet of the mass spectrometer are used as electrodes, and a piece of coverslip is used as a sample plate as well as an insulating dielectric barrier, which simplifies the configuration of instrument and thus the operation. Different from volume dielectric-barrier discharge (VDBD), the microdischarges are generated on the surface at SDDBDI, and therefore the plasma density is extremely high. Analyte ions are guided directly into the MS inlet without any deflection. This configuration significantly improves the ion transmission efficiency and thus the sensitivity. The dependence of sensitivity and spatial resolution of the SDDBDI on the operation parameters were systematically investigated. The application of SDDBDI was successfully demonstrated by analysis of multiple species including amino acids, pharmaceuticals, putative cancer biomarkers, and mixtures of both fatty acids and hormones. Limits of detection (S/N = 3) were determined to be 0.84 and 0.18 pmol, respectively, for the analysis of l-alanine and metronidazole. A spatial resolution of 22 μm was obtained for the analysis of an imprinted cyclophosphamide pattern, and imaging of a "T" character was successfully demonstrated under ambient conditions. These results indicate that SDDBDI has high-efficiency ion transmission, high sensitivity, and high spatial resolution, which render it a potential tool for mass spectrometry imaging.

A High-Resolution Stopwatch for Cents

ERIC Educational Resources Information Center

Gingl, Z.; Kopasz, K.

2011-01-01

A very low-cost, easy-to-make stopwatch is presented to support various experiments in mechanics. The high-resolution stopwatch is based on two photodetectors connected directly to the microphone input of a sound card. Dedicated free open-source software has been developed and made available to download. The efficiency is demonstrated by a free…

DMI's Baltic Sea Coastal operational forecasting system

NASA Astrophysics Data System (ADS)

Murawski, Jens; Berg, Per; Weismann Poulsen, Jacob

2017-04-01

Operational forecasting is challenged with bridging the gap between the large scales of the driving weather systems and the local, human scales of the model applications. The limit of what can be represented by local model has been continuously shifted to higher and higher spatial resolution, with the aim to better resolve the local dynamic and to make it possible to describe processes that could only be parameterised in older versions, with the ultimate goal to improve the quality of the forecast. Current hardware trends demand a str onger focus on the development of efficient, highly parallelised software and require a refactoring of the code with a solid focus on portable performance. The gained performance can be used for running high resolution model with a larger coverage. Together with the development of efficient two-way nesting routines, this has made it possible to approach the near-coastal zone with model applications that can run in a time effective way. Denmarks Meteorological Institute uses the HBM(1) ocean circulation model for applications that covers the entire Baltic Sea and North Sea with an integrated model set-up that spans the range of horizontal resolution from 1nm for the entire Baltic Sea to approx. 200m resolution in local fjords (Limfjord). For the next model generation, the high resolution set-ups are going to be extended and new high resolution domains in coastal zones are either implemented or tested for operational use. For the first time it will be possible to cover large stretches of the Baltic coastal zone with sufficiently high resolution to model the local hydrodynamic adequately. (1) HBM stands for HIROMB-BOOS-Model, whereas HIROMB stands for "High Resolution Model for the Baltic Sea" and BOOS stands for "Baltic Operational Oceanography System".

Sparse coded image super-resolution using K-SVD trained dictionary based on regularized orthogonal matching pursuit.

PubMed

Sajjad, Muhammad; Mehmood, Irfan; Baik, Sung Wook

2015-01-01

Image super-resolution (SR) plays a vital role in medical imaging that allows a more efficient and effective diagnosis process. Usually, diagnosing is difficult and inaccurate from low-resolution (LR) and noisy images. Resolution enhancement through conventional interpolation methods strongly affects the precision of consequent processing steps, such as segmentation and registration. Therefore, we propose an efficient sparse coded image SR reconstruction technique using a trained dictionary. We apply a simple and efficient regularized version of orthogonal matching pursuit (ROMP) to seek the coefficients of sparse representation. ROMP has the transparency and greediness of OMP and the robustness of the L1-minization that enhance the dictionary learning process to capture feature descriptors such as oriented edges and contours from complex images like brain MRIs. The sparse coding part of the K-SVD dictionary training procedure is modified by substituting OMP with ROMP. The dictionary update stage allows simultaneously updating an arbitrary number of atoms and vectors of sparse coefficients. In SR reconstruction, ROMP is used to determine the vector of sparse coefficients for the underlying patch. The recovered representations are then applied to the trained dictionary, and finally, an optimization leads to high-resolution output of high-quality. Experimental results demonstrate that the super-resolution reconstruction quality of the proposed scheme is comparatively better than other state-of-the-art schemes.

Fast and efficient molecule detection in localization-based super-resolution microscopy by parallel adaptive histogram equalization.

PubMed

Li, Yiming; Ishitsuka, Yuji; Hedde, Per Niklas; Nienhaus, G Ulrich

2013-06-25

In localization-based super-resolution microscopy, individual fluorescent markers are stochastically photoactivated and subsequently localized within a series of camera frames, yielding a final image with a resolution far beyond the diffraction limit. Yet, before localization can be performed, the subregions within the frames where the individual molecules are present have to be identified-oftentimes in the presence of high background. In this work, we address the importance of reliable molecule identification for the quality of the final reconstructed super-resolution image. We present a fast and robust algorithm (a-livePALM) that vastly improves the molecule detection efficiency while minimizing false assignments that can lead to image artifacts.

A high resolution on-chip delay sensor with low supply-voltage sensitivity for high-performance electronic systems.

PubMed

Sheng, Duo; Lai, Hsiu-Fan; Chan, Sheng-Min; Hong, Min-Rong

2015-02-13

An all-digital on-chip delay sensor (OCDS) circuit with high delay-measurement resolution and low supply-voltage sensitivity for efficient detection and diagnosis in high-performance electronic system applications is presented. Based on the proposed delay measurement scheme, the quantization resolution of the proposed OCDS can be reduced to several picoseconds. Additionally, the proposed cascade-stage delay measurement circuit can enhance immunity to supply-voltage variations of the delay measurement resolution without extra self-biasing or calibration circuits. Simulation results show that the delay measurement resolution can be improved to 1.2 ps; the average delay resolution variation is 0.55% with supply-voltage variations of ±10%. Moreover, the proposed delay sensor can be implemented in an all-digital manner, making it very suitable for high-performance electronic system applications as well as system-level integration.

Spiral Transformation for High-Resolution and Efficient Sorting of Optical Vortex Modes.

PubMed

Wen, Yuanhui; Chremmos, Ioannis; Chen, Yujie; Zhu, Jiangbo; Zhang, Yanfeng; Yu, Siyuan

2018-05-11

Mode sorting is an essential function for optical multiplexing systems that exploit the orthogonality of the orbital angular momentum mode space. The familiar log-polar optical transformation provides a simple yet efficient approach whose resolution is, however, restricted by a considerable overlap between adjacent modes resulting from the limited excursion of the phase along a complete circle around the optical vortex axis. We propose and experimentally verify a new optical transformation that maps spirals (instead of concentric circles) to parallel lines. As the phase excursion along a spiral in the wave front of an optical vortex is theoretically unlimited, this new optical transformation can separate orbital angular momentum modes with superior resolution while maintaining unity efficiency.

Spiral Transformation for High-Resolution and Efficient Sorting of Optical Vortex Modes

NASA Astrophysics Data System (ADS)

Wen, Yuanhui; Chremmos, Ioannis; Chen, Yujie; Zhu, Jiangbo; Zhang, Yanfeng; Yu, Siyuan

2018-05-01

Mode sorting is an essential function for optical multiplexing systems that exploit the orthogonality of the orbital angular momentum mode space. The familiar log-polar optical transformation provides a simple yet efficient approach whose resolution is, however, restricted by a considerable overlap between adjacent modes resulting from the limited excursion of the phase along a complete circle around the optical vortex axis. We propose and experimentally verify a new optical transformation that maps spirals (instead of concentric circles) to parallel lines. As the phase excursion along a spiral in the wave front of an optical vortex is theoretically unlimited, this new optical transformation can separate orbital angular momentum modes with superior resolution while maintaining unity efficiency.

IONIZED GAS KINEMATICS AT HIGH RESOLUTION. V. [Ne ii], MULTIPLE CLUSTERS, HIGH EFFICIENCY STAR FORMATION, AND BLUE FLOWS IN HE 2–10

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

Beck, Sara; Turner, Jean; Lacy, John

2015-11-20

We measured the 12.8 μm [Ne ii] line in the dwarf starburst galaxy He 2–10 with the high-resolution spectrometer TEXES on the NASA IRTF. The data cube has a diffraction-limited spatial resolution of ∼1″ and a total velocity resolution, including thermal broadening, of ∼5 km s{sup −1}. This makes it possible to compare the kinematics of individual star-forming clumps and molecular clouds in the three dimensions of space and velocity, and allows us to determine star formation efficiencies. The kinematics of the ionized gas confirm that the starburst contains multiple dense clusters. From the M/R of the clusters and themore » ≃30%–40% star formation efficiencies, the clusters are likely to be bound and long lived, like globulars. Non-gravitational features in the line profiles show how the ionized gas flows through the ambient molecular material, as well as a narrow velocity feature, which we identify with the interface of the H ii region and a cold dense clump. These data offer an unprecedented view of the interaction of embedded H ii regions with their environment.« less

Impacts of high resolution data on traveler compliance levels in emergency evacuation simulations

DOE PAGES

Lu, Wei; Han, Lee D.; Liu, Cheng; ...

2016-05-05

In this article, we conducted a comparison study of evacuation assignment based on Traffic Analysis Zones (TAZ) and high resolution LandScan USA Population Cells (LPC) with detailed real world roads network. A platform for evacuation modeling built on high resolution population distribution data and activity-based microscopic traffic simulation was proposed. This platform can be extended to any cities in the world. The results indicated that evacuee compliance behavior affects evacuation efficiency with traditional TAZ assignment, but it did not significantly compromise the performance with high resolution LPC assignment. The TAZ assignment also underestimated the real travel time during evacuation. Thismore » suggests that high data resolution can improve the accuracy of traffic modeling and simulation. The evacuation manager should consider more diverse assignment during emergency evacuation to avoid congestions.« less

Monolithic focused reference beam X-ray holography

PubMed Central

Geilhufe, J.; Pfau, B.; Schneider, M.; Büttner, F.; Günther, C. M.; Werner, S.; Schaffert, S.; Guehrs, E.; Frömmel, S.; Kläui, M.; Eisebitt, S.

2014-01-01

Fourier transform holography is a highly efficient and robust imaging method, suitable for single-shot imaging at coherent X-ray sources. In its common implementation, the image contrast is limited by the reference signal generated by a small pinhole aperture. Increased pinhole diameters improve the signal, whereas the resolution is diminished. Here we report a new concept to decouple the spatial resolution from the image contrast by employing a Fresnel zone plate to provide the reference beam. Superimposed on-axis images of distinct foci are separated with a novel algorithm. Our method is insensitive to mechanical drift or vibrations and allows for long integration times common at low-flux facilities like high harmonic generation sources. The application of monolithic focused reference beams improves the efficiency of high-resolution X-ray Fourier transform holography beyond all present approaches and paves the path towards sub-10 nm single-shot X-ray imaging. PMID:24394675

A flexible and accurate digital volume correlation method applicable to high-resolution volumetric images

NASA Astrophysics Data System (ADS)

Pan, Bing; Wang, Bo

2017-10-01

Digital volume correlation (DVC) is a powerful technique for quantifying interior deformation within solid opaque materials and biological tissues. In the last two decades, great efforts have been made to improve the accuracy and efficiency of the DVC algorithm. However, there is still a lack of a flexible, robust and accurate version that can be efficiently implemented in personal computers with limited RAM. This paper proposes an advanced DVC method that can realize accurate full-field internal deformation measurement applicable to high-resolution volume images with up to billions of voxels. Specifically, a novel layer-wise reliability-guided displacement tracking strategy combined with dynamic data management is presented to guide the DVC computation from slice to slice. The displacements at specified calculation points in each layer are computed using the advanced 3D inverse-compositional Gauss-Newton algorithm with the complete initial guess of the deformation vector accurately predicted from the computed calculation points. Since only limited slices of interest in the reference and deformed volume images rather than the whole volume images are required, the DVC calculation can thus be efficiently implemented on personal computers. The flexibility, accuracy and efficiency of the presented DVC approach are demonstrated by analyzing computer-simulated and experimentally obtained high-resolution volume images.

Efficient preparation of enantiopure D-phenylalanine through asymmetric resolution using immobilized phenylalanine ammonia-lyase from Rhodotorula glutinis JN-1 in a recirculating packed-bed reactor.

PubMed

Zhu, Longbao; Zhou, Li; Huang, Nan; Cui, Wenjing; Liu, Zhongmei; Xiao, Ke; Zhou, Zhemin

2014-01-01

An efficient enzymatic process was developed to produce optically pure D-phenylalanine through asymmetric resolution of the racemic DL-phenylalanine using immobilized phenylalanine ammonia-lyase (RgPAL) from Rhodotorula glutinis JN-1. RgPAL was immobilized on a modified mesoporous silica support (MCM-41-NH-GA). The resulting MCM-41-NH-GA-RgPAL showed high activity and stability. The resolution efficiency using MCM-41-NH-GA-RgPAL in a recirculating packed-bed reactor (RPBR) was higher than that in a stirred-tank reactor. Under optimal operational conditions, the volumetric conversion rate of L-phenylalanine and the productivity of D-phenylalanine reached 96.7 mM h⁻¹ and 0.32 g L⁻¹ h⁻¹, respectively. The optical purity (eeD) of D-phenylalanine exceeded 99%. The RPBR ran continuously for 16 batches, the conversion ratio did not decrease. The reactor was scaled up 25-fold, and the productivity of D-phenylalanine (eeD>99%) in the scaled-up reactor reached 7.2 g L⁻¹ h⁻¹. These results suggest that the resolution process is an alternative method to produce highly pure D-phenylalanine.

Efficient Preparation of Enantiopure D-Phenylalanine through Asymmetric Resolution Using Immobilized Phenylalanine Ammonia-Lyase from Rhodotorula glutinis JN-1 in a Recirculating Packed-Bed Reactor

PubMed Central

Huang, Nan; Cui, Wenjing; Liu, Zhongmei; Xiao, Ke; Zhou, Zhemin

2014-01-01

An efficient enzymatic process was developed to produce optically pure D-phenylalanine through asymmetric resolution of the racemic DL-phenylalanine using immobilized phenylalanine ammonia-lyase (RgPAL) from Rhodotorula glutinis JN-1. RgPAL was immobilized on a modified mesoporous silica support (MCM-41-NH-GA). The resulting MCM-41-NH-GA-RgPAL showed high activity and stability. The resolution efficiency using MCM-41-NH-GA-RgPAL in a recirculating packed-bed reactor (RPBR) was higher than that in a stirred-tank reactor. Under optimal operational conditions, the volumetric conversion rate of L-phenylalanine and the productivity of D-phenylalanine reached 96.7 mM h−1 and 0.32 g L−1 h−1, respectively. The optical purity (ee D) of D-phenylalanine exceeded 99%. The RPBR ran continuously for 16 batches, the conversion ratio did not decrease. The reactor was scaled up 25-fold, and the productivity of D-phenylalanine (ee D>99%) in the scaled-up reactor reached 7.2 g L−1 h−1. These results suggest that the resolution process is an alternative method to produce highly pure D-phenylalanine. PMID:25268937

[Transmission efficiency analysis of near-field fiber probe using FDTD simulation].

PubMed

Huang, Wei; Dai, Song-Tao; Wang, Huai-Yu; Zhou, Yun-Song

2011-10-01

A fiber probe is the key component of near-field optical technology which is widely used in high resolution imaging, spectroscopy detection and nano processing. How to improve the transmission efficiency of the fiber probe is a very important problem in the application of near-field optical technology. Based on the results of 3D-FDTD computation, the dependence of the transmission efficiency on the cone angle, the aperture diameter, the wavelength and the thickness of metal cladding is revealed. The authors have also made a comparison between naked probe and the probe with metal cladding in terms of transmission efficiency and spatial resolution. In addition, the authors have discovered the fluctuation phenomena of transmission efficiency as the wavelength of incident laser increases.

Ozone-induced dissociation on a traveling wave high-resolution mass spectrometer for determination of double-bond position in lipids.

PubMed

Vu, Ngoc; Brown, Jeffery; Giles, Kevin; Zhang, Qibin

2017-09-15

The position of C=C within fatty acyl chains affects the biological function of lipids. Ozone-induced dissociation mass spectrometry (OzID-MS) has great potential in determination of lipid double-bond position, but has generally been implemented on low-resolution ion trap mass spectrometers. In addition, most of the OzID-MS experiments carried out so far were focused on the sodiated adducts of lipids; fragmentation of the most commonly observed protonated ions generated in LC/MS-based lipidomics workflow has been less explored. Ozone generated in line from an ozone generator was connected to the trap and transfer gas supply line of a Synapt G2 high-resolution mass spectrometer. Protonated ions of different phosphatidylcholines (PC) were generated by electrospray ionization through direct infusion. Different parameters, including traveling wave height and velocity, trap entrance and DC potential, were adjusted to maximize the OzID efficiency. sn-positional isomers and cis/trans isomers of lipids were compared for their reactivity with ozone. Traveling wave height and velocity were tuned to prolong the encounter time between lipid ions and ozone, and resulted in improved OzID efficiency, as did increasing trapping region DC and entrance potential. Under optimized settings, at least 1000 times enhancement in OzID efficiency was achieved compared to that under default settings for monounsaturated PC standards. Monounsaturated C=C in the sn-2 PC isomer reacted faster with ozone than the sn-1 isomer. Similarly, the C=C in trans PC reacted faster than in cis PC. This is the first implementation of OzID in the trap and transfer region of a traveling wave enabled high-resolution mass spectrometer. The OzID reaction efficiency is significantly improved by slowing down ions in the trap region for their prolonged interaction with ozone. This will facilitate application of high-resolution OzID-MS in lipidomics. Copyright © 2017 John Wiley & Sons, Ltd.

Rapid calibrated high-resolution hyperspectral imaging using tunable laser source

NASA Astrophysics Data System (ADS)

Nguyen, Lam K.; Margalith, Eli

2009-05-01

We present a novel hyperspectral imaging technique based on tunable laser technology. By replacing the broadband source and tunable filters of a typical NIR imaging instrument, several advantages are realized, including: high spectral resolution, highly variable field-of-views, fast scan-rates, high signal-to-noise ratio, and the ability to use optical fiber for efficient and flexible sample illumination. With this technique, high-resolution, calibrated hyperspectral images over the NIR range can be acquired in seconds. The performance of system features will be demonstrated on two example applications: detecting melamine contamination in wheat gluten and separating bovine protein from wheat protein in cattle feed.

High Resolution Image Reconstruction from Projection of Low Resolution Images DIffering in Subpixel Shifts

NASA Technical Reports Server (NTRS)

Mareboyana, Manohar; Le Moigne-Stewart, Jacqueline; Bennett, Jerome

2016-01-01

In this paper, we demonstrate a simple algorithm that projects low resolution (LR) images differing in subpixel shifts on a high resolution (HR) also called super resolution (SR) grid. The algorithm is very effective in accuracy as well as time efficiency. A number of spatial interpolation techniques using nearest neighbor, inverse-distance weighted averages, Radial Basis Functions (RBF) etc. used in projection yield comparable results. For best accuracy of reconstructing SR image by a factor of two requires four LR images differing in four independent subpixel shifts. The algorithm has two steps: i) registration of low resolution images and (ii) shifting the low resolution images to align with reference image and projecting them on high resolution grid based on the shifts of each low resolution image using different interpolation techniques. Experiments are conducted by simulating low resolution images by subpixel shifts and subsampling of original high resolution image and the reconstructing the high resolution images from the simulated low resolution images. The results of accuracy of reconstruction are compared by using mean squared error measure between original high resolution image and reconstructed image. The algorithm was tested on remote sensing images and found to outperform previously proposed techniques such as Iterative Back Projection algorithm (IBP), Maximum Likelihood (ML), and Maximum a posterior (MAP) algorithms. The algorithm is robust and is not overly sensitive to the registration inaccuracies.

Requirements on high resolution detectors

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

Koch, A.

For a number of microtomography applications X-ray detectors with a spatial resolution of 1 {mu}m are required. This high spatial resolution will influence and degrade other parameters of secondary importance like detective quantum efficiency (DQE), dynamic range, linearity and frame rate. This note summarizes the most important arguments, for and against those detector systems which could be considered. This article discusses the mutual dependencies between the various figures which characterize a detector, and tries to give some ideas on how to proceed in order to improve present technology.

ERIC First Analysis: 1980-81 National High School Debate Resolutions (How Can the Interests of United States Consumers Best Be Served?).

ERIC Educational Resources Information Center

Wagner, David L.

The five chapters of this book are intended to prepare high school debaters and their coaches for the efficient investigation of the 1980-81 High Scbool Debate Problem Area and Resolutions. The first chapter contains an overview of the problem area--consumer interests--describing the basic concepts of regulation and risk, the definitions of the…

JPRS Report, Science and Technology, Europe.

DTIC Science & Technology

1989-06-16

nature of their central energy sources, to the complex distribution of gases around the nucleus and possibly to understanding the origin of the diffuse...development. CCD’s are ideal for single photon X-ray imaging and spectroscopy. They have a high quantum efficiency over a broad energy range, high spatial...resolution, low readout noise, and an energy resolution approaching 100 at high energy levels. Reflection gratings have been chosen for XMM rather

Quantum Computers

DTIC Science & Technology

2010-03-04

and their sensitivity to charge and flux fluctuations. The first type of superconducting qubit , the charge qubit , omits the inductance . There is no...nanostructured NbN superconducting nanowire detectors have achieved high efficiency and photon number resolution16,17. One approach to a high-efficiency single...resemble classical high- speed integrated circuits and can be readily fabricated using existing technologies. The basic physics behind superconducting qubits

Efficiency, dispersion and straylight performance tests of immersed gratings for high resolution spectroscopy in the near infrared

NASA Astrophysics Data System (ADS)

Fernandez-Saldivar, J.; Culfaz, F.; Angli, N.; Bhatti, I.; Lobb, D.; Baister, G.; Touzet, B.; Desserouer, F.; Guldimann, B.

2017-11-01

New immersed grating technology is needed particularly for use in imaging spectrometers that will be used in sensing the atmosphere O2A spectral band (750nm - 775 nm) at spectral resolution in the order of 0.1 nm whilst ensuring a high efficiency and maintaining low stray light. In this work, the efficiency, dispersion and stray light performance of an immersed grating are tested and compared to analytical models. The grating consists of an ion-beam etched grating in a fused-silica substrate of 120 mm x 120mm immersed on to a prism of the same material. It is designed to obtain dispersions > 0.30°/nm-1 in air and >70% efficiency. The optical performance of the immersed grating is modelled and methods to measure its wavefront, efficiency, dispersion and scattered radiance are described. The optical setup allows the measurement of an 80mm beam diameter to derive the bidirectional scatter distribution function (BSDF) from the immersed grating from a minimum angle of 0.1° from the diffracted beam with angular resolution of 0.05°. Different configurations of the setup allow the efficiency and dispersion measurements using a tuneable laser in the 750nm-775nm range. The results from the tests are discussed with the suitability of the immersed gratings in mind for future space based instruments for atmospheric monitoring.

Hurricane Forecasting with the High-resolution NASA Finite-volume General Circulation Model

NASA Technical Reports Server (NTRS)

Atlas, R.; Reale, O.; Shen, B.-W.; Lin, S.-J.; Chern, J.-D.; Putman, W.; Lee, T.; Yeh, K.-S.; Bosilovich, M.; Radakovich, J.

2004-01-01

A high-resolution finite-volume General Circulation Model (fvGCM), resulting from a development effort of more than ten years, is now being run operationally at the NASA Goddard Space Flight Center and Ames Research Center. The model is based on a finite-volume dynamical core with terrain-following Lagrangian control-volume discretization and performs efficiently on massive parallel architectures. The computational efficiency allows simulations at a resolution of a quarter of a degree, which is double the resolution currently adopted by most global models in operational weather centers. Such fine global resolution brings us closer to overcoming a fundamental barrier in global atmospheric modeling for both weather and climate, because tropical cyclones and even tropical convective clusters can be more realistically represented. In this work, preliminary results of the fvGCM are shown. Fifteen simulations of four Atlantic tropical cyclones in 2002 and 2004 are chosen because of strong and varied difficulties presented to numerical weather forecasting. It is shown that the fvGCM, run at the resolution of a quarter of a degree, can produce very good forecasts of these tropical systems, adequately resolving problems like erratic track, abrupt recurvature, intense extratropical transition, multiple landfall and reintensification, and interaction among vortices.

Application of high-resolution linear Radon transform for Rayleigh-wave dispersive energy imaging and mode separating

USGS Publications Warehouse

Luo, Y.; Xia, J.; Miller, R.D.; Liu, J.; Xu, Y.; Liu, Q.

2008-01-01

Multichannel Analysis of Surface Waves (MASW) analysis is an efficient tool to obtain the vertical shear-wave profile. One of the key steps in the MASW method is to generate an image of dispersive energy in the frequency-velocity domain, so dispersion curves can be determined by picking peaks of dispersion energy. In this paper, we image Rayleigh-wave dispersive energy and separate multimodes from a multichannel record by high-resolution linear Radon transform (LRT). We first introduce Rayleigh-wave dispersive energy imaging by high-resolution LRT. We then show the process of Rayleigh-wave mode separation. Results of synthetic and real-world examples demonstrate that (1) compared with slant stacking algorithm, high-resolution LRT can improve the resolution of images of dispersion energy by more than 50% (2) high-resolution LRT can successfully separate multimode dispersive energy of Rayleigh waves with high resolution; and (3) multimode separation and reconstruction expand frequency ranges of higher mode dispersive energy, which not only increases the investigation depth but also provides a means to accurately determine cut-off frequencies.

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

Smith, Donald F.; Schulz, Carl; Konijnenburg, Marco

High-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry imaging enables the spatial mapping and identification of biomolecules from complex surfaces. The need for long time-domain transients, and thus large raw file sizes, results in a large amount of raw data (“big data”) that must be processed efficiently and rapidly. This can be compounded by largearea imaging and/or high spatial resolution imaging. For FT-ICR, data processing and data reduction must not compromise the high mass resolution afforded by the mass spectrometer. The continuous mode “Mosaic Datacube” approach allows high mass resolution visualization (0.001 Da) of mass spectrometry imaging data, butmore » requires additional processing as compared to featurebased processing. We describe the use of distributed computing for processing of FT-ICR MS imaging datasets with generation of continuous mode Mosaic Datacubes for high mass resolution visualization. An eight-fold improvement in processing time is demonstrated using a Dutch nationally available cloud service.« less

X-ray Optics Development at MSFC

NASA Technical Reports Server (NTRS)

Sharma, Dharma P.

2017-01-01

Development of high resolution focusing telescopes has led to a tremendous leap in sensitivity, revolutionizing observational X-ray astronomy. High sensitivity and high spatial resolution X-ray observations have been possible due to use of grazing incidence optics (paraboloid/hyperboloid) coupled with high spatial resolution and high efficiency detectors/imagers. The best X-ray telescope flown so far is mounted onboard Chandra observatory launched on July 23,1999. The telescope has a spatial resolution of 0.5 arc seconds with compatible imaging instruments in the energy range of 0.1 to 10 keV. The Chandra observatory has been responsible for a large number of discoveries and has provided X-ray insights on a large number of celestial objects including stars, supernova remnants, pulsars, magnetars, black holes, active galactic nuclei, galaxies, clusters and our own solar system.

LPE grown LSO:Tb scintillator films for high-resolution X-ray imaging applications at synchrotron light sources

NASA Astrophysics Data System (ADS)

Cecilia, A.; Rack, A.; Douissard, P.-A.; Martin, T.; Dos Santos Rolo, T.; Vagovič, P.; Hamann, E.; van de Kamp, T.; Riedel, A.; Fiederle, M.; Baumbach, T.

2011-08-01

Within the project ScinTAX of the 6th framework program (FP6) of the European Commission (SCINTAX—STRP 033 427) we have developed a new thin single crystal scintillator for high-resolution X-ray imaging. The scintillator is based on a Tb-doped Lu2SiO5 (LSO) film epitaxially grown on an adapted substrate. The high density, effective atomic number and light yield of the scintillating LSO significantly improves the efficiency of the X-ray imaging detectors currently used in synchrotron micro-imaging applications. In this work we present the characterization of the scintillating LSO films in terms of their spatial resolution performance and we provide two examples of high spatial and high temporal resolution applications.

Diffraction Efficiency of Thin Film Holographic Beam Steering Devices

NASA Technical Reports Server (NTRS)

Titus, Charles M.; Pouch, John; Nguyen, Hung; Miranda, Felix; Bos, Philip J.

2003-01-01

Dynamic holography has been demonstrated as a method for correcting aberrations in space deployable optics, and can also be used to achieve high-resolution beam steering in the same environment. In this paper, we consider some of the factors affecting the efficiency of these devices. Specifically, the effect on the efficiency of a highly collimated beam from the number of discrete phase steps per period is considered for a blazed thin film beam steering grating. The effect of the number of discrete phase steps per period on steering resolution is also considered. We also present some result of Finite-Difference Time-Domain (FDTD) calculations of light propagating through liquid crystal "blazed" gratings. Liquid crystal gratings are shown to spatially modulate both the phase and amplitude of the propagating light.

Efficient, deep-blue TADF-emitters for OLED display applications (Conference Presentation)

NASA Astrophysics Data System (ADS)

Volz, Daniel; Baumann, Thomas

2016-09-01

Currently, the mobile display market is strongly shifting towards AMOLED technology, in order to enable curved and flexible displays. This leads to a growing demand for highly efficient OLED emitters to reduce the power consumption and increase display resolution at the same time. While highly efficient green and red OLEDs already found their place in commercial OLED-displays, the lack of efficient blue emitters is still an issue. Consequently, the active area for blue is considerably larger than for green and red pixels, to make up for the lower efficiency. We intend to close this efficiency-gap with novel emitters based on thermally activated delayed fluorescence (TADF) technology. Compared to state-of-the-art fluorescent dopants, the efficiency of TADF-emitters is up to four times higher. At the same time, it is possible to design them in a way to maintain deep blue emission, i.e. CIE y < 0.2. These aspects are relevant to produce efficient high resolution AMOLED displays. Apart from these direct customer benefits, our TADF technology does not contain any rare elements, which allows for the fabrication of sustainable OLED technology. In this work, we highlight one of our recently developed blue TADF materials. Basic material properties as well as first device results are discussed. In a bottom-emitting device, a CIEx/CIEy coordinate of (0.16/0.17) was achieved with efficiency values close to 20% EQE.

Transferrin-mediated rapid targeting, isolation, and detection of circulating tumor cells by multifunctional magneto-dendritic nanosystem.

PubMed

Banerjee, Shashwat S; Jalota-Badhwar, Archana; Satavalekar, Sneha D; Bhansali, Sujit G; Aher, Naval D; Mascarenhas, Russel R; Paul, Debjani; Sharma, Somesh; Khandare, Jayant J

2013-06-01

A multicomponent magneto-dendritic nanosystem (MDNS) is designed for rapid tumor cell targeting, isolation, and high-resolution imaging by a facile bioconjugation approach. The highly efficient and rapid-acting MDNS provides a convenient platform for simultaneous isolation and high-resolution imaging of tumor cells, potentially leading towards an early diagnosis of cancer. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Efficient conceptual design for LED-based pixel light vehicle headlamps

NASA Astrophysics Data System (ADS)

Held, Marcel Philipp; Lachmayer, Roland

2017-12-01

High-resolution vehicle headlamps represent a future-oriented technology that can be used to increase traffic safety and driving comfort. As a further development to the current Matrix Beam headlamps, LED-based pixel light systems enable ideal lighting functions (e.g. projection of navigation information onto the road) to be activated in any given driving scenario. Moreover, compared to other light-modulating elements such as DMDs and LCDs, instantaneous LED on-off toggling provides a decisive advantage in efficiency. To generate highly individualized light distributions for automotive applications, a number of approaches using an LED array may be pursued. One approach is to vary the LED density in the array so as to output the desired light distribution. Another notable approach makes use of an equidistant arrangement of the individual LEDs together with distortion optics to formulate the desired light distribution. The optical system adjusts the light distribution in a manner that improves resolution and increases luminous intensity of the desired area. An efficient setup for pixel generation calls for one lens per LED. Taking into consideration the limited space requirements of the system, this implies that the luminous flux, efficiency and resolution image parameters are primarily controlled by the lens dimensions. In this paper a concept for an equidistant LED array arrangement utilizing distortion optics is presented. The paper is divided into two parts. The first part discusses the influence of lens geometry on the system efficiency whereas the second part investigates the correlation between resolution and luminous flux based on the lens dimensions.

Does the Data Resolution/origin Matter? Satellite, Airborne and Uav Imagery to Tackle Plant Invasions

NASA Astrophysics Data System (ADS)

Müllerová, Jana; Brůna, Josef; Dvořák, Petr; Bartaloš, Tomáš; Vítková, Michaela

2016-06-01

Invasive plant species represent a serious threat to biodiversity and landscape as well as human health and socio-economy. To successfully fight plant invasions, new methods enabling fast and efficient monitoring, such as remote sensing, are needed. In an ongoing project, optical remote sensing (RS) data of different origin (satellite, aerial and UAV), spectral (panchromatic, multispectral and color), spatial (very high to medium) and temporal resolution, and various technical approaches (object-, pixelbased and combined) are tested to choose the best strategies for monitoring of four invasive plant species (giant hogweed, black locust, tree of heaven and exotic knotweeds). In our study, we address trade-offs between spectral, spatial and temporal resolutions required for balance between the precision of detection and economic feasibility. For the best results, it is necessary to choose best combination of spatial and spectral resolution and phenological stage of the plant in focus. For species forming distinct inflorescences such as giant hogweed iterative semi-automated object-oriented approach was successfully applied even for low spectral resolution data (if pixel size was sufficient) whereas for lower spatial resolution satellite imagery or less distinct species with complicated architecture such as knotweed, combination of pixel and object based approaches was used. High accuracies achieved for very high resolution data indicate the possible application of described methodology for monitoring invasions and their long-term dynamics elsewhere, making management measures comparably precise, fast and efficient. This knowledge serves as a basis for prediction, monitoring and prioritization of management targets.

Robust High-Resolution Cloth Using Parallelism, History-Based Collisions and Accurate Friction

PubMed Central

Selle, Andrew; Su, Jonathan; Irving, Geoffrey; Fedkiw, Ronald

2015-01-01

In this paper we simulate high resolution cloth consisting of up to 2 million triangles which allows us to achieve highly detailed folds and wrinkles. Since the level of detail is also influenced by object collision and self collision, we propose a more accurate model for cloth-object friction. We also propose a robust history-based repulsion/collision framework where repulsions are treated accurately and efficiently on a per time step basis. Distributed memory parallelism is used for both time evolution and collisions and we specifically address Gauss-Seidel ordering of repulsion/collision response. This algorithm is demonstrated by several high-resolution and high-fidelity simulations. PMID:19147895

Two-photon imaging of spatially extended neuronal network dynamics with high temporal resolution.

PubMed

Lillis, Kyle P; Eng, Alfred; White, John A; Mertz, Jerome

2008-07-30

We describe a simple two-photon fluorescence imaging strategy, called targeted path scanning (TPS), to monitor the dynamics of spatially extended neuronal networks with high spatiotemporal resolution. Our strategy combines the advantages of mirror-based scanning, minimized dead time, ease of implementation, and compatibility with high-resolution low-magnification objectives. To demonstrate the performance of TPS, we monitor the calcium dynamics distributed across an entire juvenile rat hippocampus (>1.5mm), at scan rates of 100 Hz, with single cell resolution and single action potential sensitivity. Our strategy for fast, efficient two-photon microscopy over spatially extended regions provides a particularly attractive solution for monitoring neuronal population activity in thick tissue, without sacrificing the signal-to-noise ratio or high spatial resolution associated with standard two-photon microscopy. Finally, we provide the code to make our technique generally available.

High Resolution Full-Aperture ISAR Processing through Modified Doppler History Based Motion Compensation

PubMed Central

Song, Jung-Hwan; Lee, Kee-Woong; Lee, Woo-Kyung; Jung, Chul-Ho

2017-01-01

A high resolution inverse synthetic aperture radar (ISAR) technique is presented using modified Doppler history based motion compensation. To this purpose, a novel wideband ISAR system is developed that accommodates parametric processing over extended aperture length. The proposed method is derived from an ISAR-to-SAR approach that makes use of high resolution spotlight SAR and sub-aperture recombination. It is dedicated to wide aperture ISAR imaging and exhibits robust performance against unstable targets having non-linear motions. We demonstrate that the Doppler histories of the full aperture ISAR echoes from disturbed targets are efficiently retrieved with good fitting models. Experiments have been conducted on real aircraft targets and the feasibility of the full aperture ISAR processing is verified through the acquisition of high resolution ISAR imagery. PMID:28555036

A fast mass spring model solver for high-resolution elastic objects

NASA Astrophysics Data System (ADS)

Zheng, Mianlun; Yuan, Zhiyong; Zhu, Weixu; Zhang, Guian

2017-03-01

Real-time simulation of elastic objects is of great importance for computer graphics and virtual reality applications. The fast mass spring model solver can achieve visually realistic simulation in an efficient way. Unfortunately, this method suffers from resolution limitations and lack of mechanical realism for a surface geometry model, which greatly restricts its application. To tackle these problems, in this paper we propose a fast mass spring model solver for high-resolution elastic objects. First, we project the complex surface geometry model into a set of uniform grid cells as cages through *cages mean value coordinate method to reflect its internal structure and mechanics properties. Then, we replace the original Cholesky decomposition method in the fast mass spring model solver with a conjugate gradient method, which can make the fast mass spring model solver more efficient for detailed surface geometry models. Finally, we propose a graphics processing unit accelerated parallel algorithm for the conjugate gradient method. Experimental results show that our method can realize efficient deformation simulation of 3D elastic objects with visual reality and physical fidelity, which has a great potential for applications in computer animation.

On the Fringe Field of Wide Angle LC Optical Phased Array

NASA Technical Reports Server (NTRS)

Wang, Xighua; Wang, Bin; Bos, Philip J.; Anderson, James E.; Pouch, John; Miranda, Felix; McManamon, Paul F.

2004-01-01

For free space laser communication, light weighted large deployable optics is a critical component for the transmitter. However, such an optical element will introduce large aberrations due to the fact that the surface figure of the large optics is susceptable to deformation in the space environment. We propose to use a high-resolution liquid crystal spatial light modulator to correct for wavefront aberrations introduced by the primary optical element, and to achieve very fine beam steering and shaping at the same time. A 2-D optical phased array (OPA) antenna based on a Liquid Crystal on Silicon (LCOS) spatial light modulator is described. This device offers a combination of low cost, high resolution, high accuracy, high diffraction efficiency at video speed. To quantitatively understand the influence factor of the different design parameters, a computer simulation of the device is given by the 2-D director simulation and the Finite Difference Time domain (FDTD) simulation. For the 1-D OPA, we define the maximum steering angle to have a grating period of 8 pixel/reset scheme; as for larger steering angles than this criterion, the diffraction efficiency drops dramatically. In this case, the diffraction efficiency of 0.86 and the Strehl ratio of 0.9 are obtained in the simulation. The performance of the device in achieving high resolution wavefront correction and beam steering is also characterized experimentally.

Design Method For Ultra-High Resolution Linear CCD Imagers

NASA Astrophysics Data System (ADS)

Sheu, Larry S.; Truong, Thanh; Yuzuki, Larry; Elhatem, Abdul; Kadekodi, Narayan

1984-11-01

This paper presents the design method to achieve ultra-high resolution linear imagers. This method utilizes advanced design rules and novel staggered bilinear photo sensor arrays with quadrilinear shift registers. Design constraint in the detector arrays and shift registers are analyzed. Imager architecture to achieve ultra-high resolution is presented. The characteristics of MTF, aliasing, speed, transfer efficiency and fine photolithography requirements associated with this architecture are also discussed. A CCD imager with advanced 1.5 um minimum feature size was fabricated. It is intended as a test vehicle for the next generation small sampling pitch ultra-high resolution CCD imager. Standard double-poly, two-phase shift registers were fabricated at an 8 um pitch using the advanced design rules. A special process step that blocked the source-drain implant from the shift register area was invented. This guaranteed excellent performance of the shift registers regardless of the small poly overlaps. A charge transfer efficiency of better than 0.99995 and maximum transfer speed of 8 MHz were achieved. The imager showed excellent performance. The dark current was less than 0.2 mV/ms, saturation 250 mV, adjacent photoresponse non-uniformity ± 4% and responsivity 0.7 V/ μJ/cm2 for the 8 μm x 6 μm photosensor size. The MTF was 0.6 at 62.5 cycles/mm. These results confirm the feasibility of the next generation ultra-high resolution CCD imagers.

Single-shot and single-sensor high/super-resolution microwave imaging based on metasurface.

PubMed

Wang, Libo; Li, Lianlin; Li, Yunbo; Zhang, Hao Chi; Cui, Tie Jun

2016-06-01

Real-time high-resolution (including super-resolution) imaging with low-cost hardware is a long sought-after goal in various imaging applications. Here, we propose broadband single-shot and single-sensor high-/super-resolution imaging by using a spatio-temporal dispersive metasurface and an imaging reconstruction algorithm. The metasurface with spatio-temporal dispersive property ensures the feasibility of the single-shot and single-sensor imager for super- and high-resolution imaging, since it can convert efficiently the detailed spatial information of the probed object into one-dimensional time- or frequency-dependent signal acquired by a single sensor fixed in the far-field region. The imaging quality can be improved by applying a feature-enhanced reconstruction algorithm in post-processing, and the desired imaging resolution is related to the distance between the object and metasurface. When the object is placed in the vicinity of the metasurface, the super-resolution imaging can be realized. The proposed imaging methodology provides a unique means to perform real-time data acquisition, high-/super-resolution images without employing expensive hardware (e.g. mechanical scanner, antenna array, etc.). We expect that this methodology could make potential breakthroughs in the areas of microwave, terahertz, optical, and even ultrasound imaging.

Tracking fronts in solutions of the shallow-water equations

NASA Astrophysics Data System (ADS)

Bennett, Andrew F.; Cummins, Patrick F.

1988-02-01

A front-tracking algorithm of Chern et al. (1986) is tested on the shallow-water equations, using the Parrett and Cullen (1984) and Williams and Hori (1970) initial state, consisting of smooth finite amplitude waves depending on one space dimension alone. At high resolution the solution is almost indistinguishable from that obtained with the Glimm algorithm. The latter is known to converge to the true frontal solution, but is 20 times less efficient at the same resolution. The solutions obtained using the front-tracking algorithm at 8 times coarser resolution are quite acceptable, indicating a very substantial gain in efficiency, which encourages application in realistic ocean models possessing two or three space dimensions.

Efficient phase contrast imaging in STEM using a pixelated detector. Part 1: Experimental demonstration at atomic resolution

DOE PAGES

Pennycook, Timothy J.; Lupini, Andrew R.; Yang, Hao; ...

2014-10-15

In this paper, we demonstrate a method to achieve high efficiency phase contrast imaging in aberration corrected scanning transmission electron microscopy (STEM) with a pixelated detector. The pixelated detector is used to record the Ronchigram as a function of probe position which is then analyzed with ptychography. Ptychography has previously been used to provide super-resolution beyond the diffraction limit of the optics, alongside numerically correcting for spherical aberration. Here we rely on a hardware aberration corrector to eliminate aberrations, but use the pixelated detector data set to utilize the largest possible volume of Fourier space to create high efficiency phasemore » contrast images. The use of ptychography to diagnose the effects of chromatic aberration is also demonstrated. In conclusion, the four dimensional dataset is used to compare different bright field detector configurations from the same scan for a sample of bilayer graphene. Our method of high efficiency ptychography produces the clearest images, while annular bright field produces almost no contrast for an in-focus aberration-corrected probe.« less

Precise and fast spatial-frequency analysis using the iterative local Fourier transform.

PubMed

Lee, Sukmock; Choi, Heejoo; Kim, Dae Wook

2016-09-19

The use of the discrete Fourier transform has decreased since the introduction of the fast Fourier transform (fFT), which is a numerically efficient computing process. This paper presents the iterative local Fourier transform (ilFT), a set of new processing algorithms that iteratively apply the discrete Fourier transform within a local and optimal frequency domain. The new technique achieves 2¹⁰ times higher frequency resolution than the fFT within a comparable computation time. The method's superb computing efficiency, high resolution, spectrum zoom-in capability, and overall performance are evaluated and compared to other advanced high-resolution Fourier transform techniques, such as the fFT combined with several fitting methods. The effectiveness of the ilFT is demonstrated through the data analysis of a set of Talbot self-images (1280 × 1024 pixels) obtained with an experimental setup using grating in a diverging beam produced by a coherent point source.

A Bike Built for Magnetic Mapping

NASA Astrophysics Data System (ADS)

Schattner, U.; Segev, A.; Lyakhovsky, V.

2017-12-01

Understanding the magnetic signature of the subsurface geology is crucial for structural, groundwater, earthquake propagation, and mineral studies. The cheapest measuring method is by walking with sensors. This approach yields high-resolution maps, yet its coverage is limited. We invented a new design that records magnetic data while riding a bicycle. The new concept offers an efficient, low-cost method of collecting high-resolution ground magnetic field data over rough terrain where conventional vehicles dare not venture. It improves the efficiency of the traditional method by more than five times. The Bike-magnetic scales up ground magnetism from a localized site survey to regional coverage. By now we covered 3300 square KM (about the size of Rhode Island) across northern Israel, in profile spacing of 1-2 km. Initial Total Magnetic Intensity maps reveal a myriad of new features that were not detected by the low-resolution regional aeromagnetic survey that collected data from 1000 m height.

Quiet echo planar imaging for functional and diffusion MRI

PubMed Central

Price, Anthony N.; Cordero‐Grande, Lucilio; Malik, Shaihan; Ferrazzi, Giulio; Gaspar, Andreia; Hughes, Emer J.; Christiaens, Daan; McCabe, Laura; Schneider, Torben; Rutherford, Mary A.; Hajnal, Joseph V.

2017-01-01

Purpose To develop a purpose‐built quiet echo planar imaging capability for fetal functional and diffusion scans, for which acoustic considerations often compromise efficiency and resolution as well as angular/temporal coverage. Methods The gradient waveforms in multiband‐accelerated single‐shot echo planar imaging sequences have been redesigned to minimize spectral content. This includes a sinusoidal read‐out with a single fundamental frequency, a constant phase encoding gradient, overlapping smoothed CAIPIRINHA blips, and a novel strategy to merge the crushers in diffusion MRI. These changes are then tuned in conjunction with the gradient system frequency response function. Results Maintained image quality, SNR, and quantitative diffusion values while reducing acoustic noise up to 12 dB (A) is illustrated in two adult experiments. Fetal experiments in 10 subjects covering a range of parameters depict the adaptability and increased efficiency of quiet echo planar imaging. Conclusion Purpose‐built for highly efficient multiband fetal echo planar imaging studies, the presented framework reduces acoustic noise for all echo planar imaging‐based sequences. Full optimization by tuning to the gradient frequency response functions allows for a maximally time‐efficient scan within safe limits. This allows ambitious in‐utero studies such as functional brain imaging with high spatial/temporal resolution and diffusion scans with high angular/spatial resolution to be run in a highly efficient manner at acceptable sound levels. Magn Reson Med 79:1447–1459, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:28653363

Characterization of scintillator-based detectors for few-ten-keV high-spatial-resolution x-ray imaging

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

Larsson, Jakob C., E-mail: jakob.larsson@biox.kth.se; Lundström, Ulf; Hertz, Hans M.

2016-06-15

Purpose: High-spatial-resolution x-ray imaging in the few-ten-keV range is becoming increasingly important in several applications, such as small-animal imaging and phase-contrast imaging. The detector properties critically influence the quality of such imaging. Here the authors present a quantitative comparison of scintillator-based detectors for this energy range and at high spatial frequencies. Methods: The authors determine the modulation transfer function, noise power spectrum (NPS), and detective quantum efficiency for Gadox, needle CsI, and structured CsI scintillators of different thicknesses and at different photon energies. An extended analysis of the NPS allows for direct measurements of the scintillator effective absorption efficiency andmore » effective light yield as well as providing an alternative method to assess the underlying factors behind the detector properties. Results: There is a substantial difference in performance between the scintillators depending on the imaging task but in general, the CsI based scintillators perform better than the Gadox scintillators. At low energies (16 keV), a thin needle CsI scintillator has the best performance at all frequencies. At higher energies (28–38 keV), the thicker needle CsI scintillators and the structured CsI scintillator all have very good performance. The needle CsI scintillators have higher absorption efficiencies but the structured CsI scintillator has higher resolution. Conclusions: The choice of scintillator is greatly dependent on the imaging task. The presented comparison and methodology will assist the imaging scientist in optimizing their high-resolution few-ten-keV imaging system for best performance.« less

Characterization of scintillator-based detectors for few-ten-keV high-spatial-resolution x-ray imaging.

PubMed

Larsson, Jakob C; Lundström, Ulf; Hertz, Hans M

2016-06-01

High-spatial-resolution x-ray imaging in the few-ten-keV range is becoming increasingly important in several applications, such as small-animal imaging and phase-contrast imaging. The detector properties critically influence the quality of such imaging. Here the authors present a quantitative comparison of scintillator-based detectors for this energy range and at high spatial frequencies. The authors determine the modulation transfer function, noise power spectrum (NPS), and detective quantum efficiency for Gadox, needle CsI, and structured CsI scintillators of different thicknesses and at different photon energies. An extended analysis of the NPS allows for direct measurements of the scintillator effective absorption efficiency and effective light yield as well as providing an alternative method to assess the underlying factors behind the detector properties. There is a substantial difference in performance between the scintillators depending on the imaging task but in general, the CsI based scintillators perform better than the Gadox scintillators. At low energies (16 keV), a thin needle CsI scintillator has the best performance at all frequencies. At higher energies (28-38 keV), the thicker needle CsI scintillators and the structured CsI scintillator all have very good performance. The needle CsI scintillators have higher absorption efficiencies but the structured CsI scintillator has higher resolution. The choice of scintillator is greatly dependent on the imaging task. The presented comparison and methodology will assist the imaging scientist in optimizing their high-resolution few-ten-keV imaging system for best performance.

An efficient implementation of 3D high-resolution imaging for large-scale seismic data with GPU/CPU heterogeneous parallel computing

NASA Astrophysics Data System (ADS)

Xu, Jincheng; Liu, Wei; Wang, Jin; Liu, Linong; Zhang, Jianfeng

2018-02-01

De-absorption pre-stack time migration (QPSTM) compensates for the absorption and dispersion of seismic waves by introducing an effective Q parameter, thereby making it an effective tool for 3D, high-resolution imaging of seismic data. Although the optimal aperture obtained via stationary-phase migration reduces the computational cost of 3D QPSTM and yields 3D stationary-phase QPSTM, the associated computational efficiency is still the main problem in the processing of 3D, high-resolution images for real large-scale seismic data. In the current paper, we proposed a division method for large-scale, 3D seismic data to optimize the performance of stationary-phase QPSTM on clusters of graphics processing units (GPU). Then, we designed an imaging point parallel strategy to achieve an optimal parallel computing performance. Afterward, we adopted an asynchronous double buffering scheme for multi-stream to perform the GPU/CPU parallel computing. Moreover, several key optimization strategies of computation and storage based on the compute unified device architecture (CUDA) were adopted to accelerate the 3D stationary-phase QPSTM algorithm. Compared with the initial GPU code, the implementation of the key optimization steps, including thread optimization, shared memory optimization, register optimization and special function units (SFU), greatly improved the efficiency. A numerical example employing real large-scale, 3D seismic data showed that our scheme is nearly 80 times faster than the CPU-QPSTM algorithm. Our GPU/CPU heterogeneous parallel computing framework significant reduces the computational cost and facilitates 3D high-resolution imaging for large-scale seismic data.

Evaluation of a High Pressure Proportional Counter for the Detection of Radioactive Noble Gases

DTIC Science & Technology

1987-01-01

Multiplication Curves Compared to Reconstructed Literature Curves .. .. ............ .81 6.4 Resolution .... . .. ......................... .... 90 v Figure...with 57 ~/57 energy resolution to 12% fwhm for Co photopeaks (-122 keV),sing argon fill gas at fifty atmospheres. Subsequent effects 0f a contami- nant...internal gas proportional counters for measuring low-level environmental radionuclides, resolutions to 27% fwhm and intrinsic efficiencies to 3 75

Main High-Resolution Near-IR Spectrometer for the VLT

NASA Astrophysics Data System (ADS)

Piskunov, N.

2017-06-01

We present the ongoing CRISES+ project on the development of a cross-dispersed high resolution near-infrared spectrometer for the ESO Very Large Telescope. The presentation highlights the relation between science objectives, technical solutions, and the structure of the project. We also share some of the insights on the implementation and management of the project that are crucial for keeping the tight time-line through efficient interaction between consortium members.

Further developments of series-connected superconducting tunnel junction to radiation detection

NASA Astrophysics Data System (ADS)

Kurakado, Masahiko; Ohsawa, Daisuke; Katano, Rintaro; Ito, Shin; Isozumi, Yasuhito

1997-10-01

One of the promising radiation detection devices for various practical applications is the series-connected superconducting tunnel junction (STJ) detector. In this article, interesting topics of the detectors are described since our previous work: e.g., more than two order higher detection efficiency compared with single STJ detectors, high count rate detection, and position resolution. Detectors were cooled to 0.35-0.4 K by means of a convenient 3He cryostat. The 5.9 and 6.5 keV x rays from 55Fe are separated by a detector specially designed for x-ray detection. The possible count rate of the series-junction detector estimated from the shaping-time constant applied in the measurements is high, e.g., over 104 counts per second. A series-junction detector equipped with a position sensing mechanism has shown a position resolution of about 35 μm in a sensing area with a radius of 1.1 mm. The position resolution of series junctions improves the energy resolution. A new type series-connected STJ detector is also proposed, i.e., the dispersed multitrap series-junction detector, for further improvement of detection efficiency and energy resolution.

Coupling of the recoil mass spectrometer CAMEL to the γ-ray spectrometer GASP

NASA Astrophysics Data System (ADS)

Spolaore, P.; Ackermann, D.; Bednarczyk, P.; De Angelis, G.; Napoli, D.; Rossi Alvarez, C.; Bazzacco, D.; Burch, R.; Müller, L.; Segato, G. F.; Scarlassara, F.

1995-02-01

A project has been realized to link the CAMEL recoil mass spectrometer to the GASP γ-spectrometer in order to perform high resolution and efficiency γ-recoil coincidence measurements. To preserve high flexibility and autonomy in the operation of the two complex apparatus a rough factor two of reduction in the overall heavy ion transmission was accepted in designing the optics of the particle transport from the GASP center to the CAMEL focal plane. The coupled configuration has been tested with the fusion reaction 58Ni (E = 212 MeV) + 64Ni, obtaining a mass resolution of {1}/{300} and efficiency between ˜ 11% and ˜ 15% for different evaporation products.

Demonstration Of Ultra HI-FI (UHF) Methods

NASA Technical Reports Server (NTRS)

Dyson, Rodger W.

2004-01-01

Computational aero-acoustics (CAA) requires efficient, high-resolution simulation tools. Most current techniques utilize finite-difference approaches because high order accuracy is considered too difficult or expensive to achieve with finite volume or finite element methods. However, a novel finite volume approach (Ultra HI-FI or UHF) which utilizes Hermite fluxes is presented which can achieve both arbitrary accuracy and fidelity in space and time. The technique can be applied to unstructured grids with some loss of fidelity or with multi-block structured grids for maximum efficiency and resolution. In either paradigm, it is possible to resolve ultra-short waves (less than 2 PPW). This is demonstrated here by solving the 4th CAA workshop Category 1 Problem 1.

LITE microscopy: Tilted light-sheet excitation of model organisms offers high resolution and low photobleaching

PubMed Central

Gerbich, Therese M.; Rana, Kishan; Suzuki, Aussie; Schaefer, Kristina N.; Heppert, Jennifer K.; Boothby, Thomas C.; Allbritton, Nancy L.; Gladfelter, Amy S.; Maddox, Amy S.

2018-01-01

Fluorescence microscopy is a powerful approach for studying subcellular dynamics at high spatiotemporal resolution; however, conventional fluorescence microscopy techniques are light-intensive and introduce unnecessary photodamage. Light-sheet fluorescence microscopy (LSFM) mitigates these problems by selectively illuminating the focal plane of the detection objective by using orthogonal excitation. Orthogonal excitation requires geometries that physically limit the detection objective numerical aperture (NA), thereby limiting both light-gathering efficiency (brightness) and native spatial resolution. We present a novel live-cell LSFM method, lateral interference tilted excitation (LITE), in which a tilted light sheet illuminates the detection objective focal plane without a sterically limiting illumination scheme. LITE is thus compatible with any detection objective, including oil immersion, without an upper NA limit. LITE combines the low photodamage of LSFM with high resolution, high brightness, and coverslip-based objectives. We demonstrate the utility of LITE for imaging animal, fungal, and plant model organisms over many hours at high spatiotemporal resolution. PMID:29490939

A CMOS-based high-resolution fluoroscope (HRF) detector prototype with 49.5μm pixels for use in endovascular image guided interventions (EIGI)

NASA Astrophysics Data System (ADS)

Russ, M.; Shankar, A.; Setlur Nagesh, S. V.; Ionita, C. N.; Bednarek, D. R.; Rudin, S.

2017-03-01

X-ray detectors to meet the high-resolution requirements for endovascular image-guided interventions (EIGIs) are being developed and evaluated. A new 49.5-micron pixel prototype detector is being investigated and compared to the current suite of high-resolution fluoroscopic (HRF) detectors. This detector featuring a 300-micron thick CsI(Tl) scintillator, and low electronic noise CMOS readout is designated the HRF- CMOS50. To compare the abilities of this detector with other existing high resolution detectors, a standard performance metric analysis was applied, including the determination of the modulation transfer function (MTF), noise power spectra (NPS), noise equivalent quanta (NEQ), and detective quantum efficiency (DQE) for a range of energies and exposure levels. The advantage of the smaller pixel size and reduced blurring due to the thin phosphor was exemplified when the MTF of the HRF-CMOS50 was compared to the other high resolution detectors, which utilize larger pixels, other optical designs or thicker scintillators. However, the thinner scintillator has the disadvantage of a lower quantum detective efficiency (QDE) for higher diagnostic x-ray energies. The performance of the detector as part of an imaging chain was examined by employing the generalized metrics GMTF, GNEQ, and GDQE, taking standard focal spot size and clinical imaging parameters into consideration. As expected, the disparaging effects of focal spot unsharpness, exacerbated by increasing magnification, degraded the higher-frequency performance of the HRF-CMOS50, while increasing scatter fraction diminished low-frequency performance. Nevertheless, the HRF-CMOS50 brings improved resolution capabilities for EIGIs, but would require increased sensitivity and dynamic range for future clinical application.

Velocity map imaging using an in-vacuum pixel detector.

PubMed

Gademann, Georg; Huismans, Ymkje; Gijsbertsen, Arjan; Jungmann, Julia; Visschers, Jan; Vrakking, Marc J J

2009-10-01

The use of a new type in-vacuum pixel detector in velocity map imaging (VMI) is introduced. The Medipix2 and Timepix semiconductor pixel detectors (256 x 256 square pixels, 55 x 55 microm2) are well suited for charged particle detection. They offer high resolution, low noise, and high quantum efficiency. The Medipix2 chip allows double energy discrimination by offering a low and a high energy threshold. The Timepix detector allows to record the incidence time of a particle with a temporal resolution of 10 ns and a dynamic range of 160 micros. Results of the first time application of the Medipix2 detector to VMI are presented, investigating the quantum efficiency as well as the possibility to operate at increased background pressure in the vacuum chamber.

Performance comparison between the high-speed Yokogawa spinning disc confocal system and single-point scanning confocal systems.

PubMed

Wang, E; Babbey, C M; Dunn, K W

2005-05-01

Fluorescence microscopy of the dynamics of living cells presents a special challenge to a microscope imaging system, simultaneously requiring both high spatial resolution and high temporal resolution, but with illumination levels low enough to prevent fluorophore damage and cytotoxicity. We have compared the high-speed Yokogawa CSU10 spinning disc confocal system with several conventional single-point scanning confocal (SPSC) microscopes, using the relationship between image signal-to-noise ratio and fluorophore photobleaching as an index of system efficiency. These studies demonstrate that the efficiency of the CSU10 consistently exceeds that of the SPSC systems. The high efficiency of the CSU10 means that quality images can be collected with much lower levels of illumination; the CSU10 was capable of achieving the maximum signal-to-noise of an SPSC system at illumination levels that incur only at 1/15th of the rate of the photobleaching of the SPSC system. Although some of the relative efficiency of the CSU10 system may be attributed to the use of a CCD rather than a photomultiplier detector system, our analyses indicate that high-speed imaging with the SPSC system is limited by fluorescence saturation at the high levels of illumination frequently needed to collect images at high frame rates. The high speed, high efficiency and freedom from fluorescence saturation combine to make the CSU10 effective for extended imaging of living cells at rates capable of capturing the three-dimensional motion of endosomes moving up to several micrometres per second.

Fast High Resolution Volume Carving for 3D Plant Shoot Reconstruction

PubMed Central

Scharr, Hanno; Briese, Christoph; Embgenbroich, Patrick; Fischbach, Andreas; Fiorani, Fabio; Müller-Linow, Mark

2017-01-01

Volume carving is a well established method for visual hull reconstruction and has been successfully applied in plant phenotyping, especially for 3d reconstruction of small plants and seeds. When imaging larger plants at still relatively high spatial resolution (≤1 mm), well known implementations become slow or have prohibitively large memory needs. Here we present and evaluate a computationally efficient algorithm for volume carving, allowing e.g., 3D reconstruction of plant shoots. It combines a well-known multi-grid representation called “Octree” with an efficient image region integration scheme called “Integral image.” Speedup with respect to less efficient octree implementations is about 2 orders of magnitude, due to the introduced refinement strategy “Mark and refine.” Speedup is about a factor 1.6 compared to a highly optimized GPU implementation using equidistant voxel grids, even without using any parallelization. We demonstrate the application of this method for trait derivation of banana and maize plants. PMID:29033961

Gaussian decomposition of high-resolution melt curve derivatives for measuring genome-editing efficiency

PubMed Central

Zaboikin, Michail; Freter, Carl

2018-01-01

We describe a method for measuring genome editing efficiency from in silico analysis of high-resolution melt curve data. The melt curve data derived from amplicons of genome-edited or unmodified target sites were processed to remove the background fluorescent signal emanating from free fluorophore and then corrected for temperature-dependent quenching of fluorescence of double-stranded DNA-bound fluorophore. Corrected data were normalized and numerically differentiated to obtain the first derivatives of the melt curves. These were then mathematically modeled as a sum or superposition of minimal number of Gaussian components. Using Gaussian parameters determined by modeling of melt curve derivatives of unedited samples, we were able to model melt curve derivatives from genetically altered target sites where the mutant population could be accommodated using an additional Gaussian component. From this, the proportion contributed by the mutant component in the target region amplicon could be accurately determined. Mutant component computations compared well with the mutant frequency determination from next generation sequencing data. The results were also consistent with our earlier studies that used difference curve areas from high-resolution melt curves for determining the efficiency of genome-editing reagents. The advantage of the described method is that it does not require calibration curves to estimate proportion of mutants in amplicons of genome-edited target sites. PMID:29300734

High efficiency quantum cascade laser frequency comb.

PubMed

Lu, Quanyong; Wu, Donghai; Slivken, Steven; Razeghi, Manijeh

2017-03-06

An efficient mid-infrared frequency comb source is of great interest to high speed, high resolution spectroscopy and metrology. Here we demonstrate a mid-IR quantum cascade laser frequency comb with a high power output and narrow beatnote linewidth at room temperature. The active region was designed with a strong-coupling between the injector and the upper lasing level for high internal quantum efficiency and a broadband gain. The group velocity dispersion was engineered for efficient, broadband mode-locking via four wave mixing. The comb device exhibits a narrow intermode beatnote linewidth of 50.5 Hz and a maximum wall-plug efficiency of 6.5% covering a spectral coverage of 110 cm -1 at λ ~ 8 μm. The efficiency is improved by a factor of 6 compared with previous demonstrations. The high power efficiency and narrow beatnote linewidth will greatly expand the applications of quantum cascade laser frequency combs including high-precision remote sensing and spectroscopy.

High efficiency quantum cascade laser frequency comb

PubMed Central

Lu, Quanyong; Wu, Donghai; Slivken, Steven; Razeghi, Manijeh

2017-01-01

An efficient mid-infrared frequency comb source is of great interest to high speed, high resolution spectroscopy and metrology. Here we demonstrate a mid-IR quantum cascade laser frequency comb with a high power output and narrow beatnote linewidth at room temperature. The active region was designed with a strong-coupling between the injector and the upper lasing level for high internal quantum efficiency and a broadband gain. The group velocity dispersion was engineered for efficient, broadband mode-locking via four wave mixing. The comb device exhibits a narrow intermode beatnote linewidth of 50.5 Hz and a maximum wall-plug efficiency of 6.5% covering a spectral coverage of 110 cm−1 at λ ~ 8 μm. The efficiency is improved by a factor of 6 compared with previous demonstrations. The high power efficiency and narrow beatnote linewidth will greatly expand the applications of quantum cascade laser frequency combs including high-precision remote sensing and spectroscopy. PMID:28262834

Resolution enhancement of low-quality videos using a high-resolution frame

NASA Astrophysics Data System (ADS)

Pham, Tuan Q.; van Vliet, Lucas J.; Schutte, Klamer

2006-01-01

This paper proposes an example-based Super-Resolution (SR) algorithm of compressed videos in the Discrete Cosine Transform (DCT) domain. Input to the system is a Low-Resolution (LR) compressed video together with a High-Resolution (HR) still image of similar content. Using a training set of corresponding LR-HR pairs of image patches from the HR still image, high-frequency details are transferred from the HR source to the LR video. The DCT-domain algorithm is much faster than example-based SR in spatial domain 6 because of a reduction in search dimensionality, which is a direct result of the compact and uncorrelated DCT representation. Fast searching techniques like tree-structure vector quantization 16 and coherence search1 are also key to the improved efficiency. Preliminary results on MJPEG sequence show promising result of the DCT-domain SR synthesis approach.

View planetary differentiation process through high-resolution 3D imaging

NASA Astrophysics Data System (ADS)

Fei, Y.

2011-12-01

Core-mantle separation is one of the most important processes in planetary evolution, defining the structure and chemical distribution in the planets. Iron-dominated core materials could migrate through silicate mantle to the core by efficient liquid-liquid separation and/or by percolation of liquid metal through solid silicate matrix. We can experimentally simulate these processes to examine the efficiency and time of core formation and its geochemical signatures. The quantitative measure of the efficiency of percolation is usually the dihedral angle, related to the interfacial energies of the liquid and solid phases. To determine the true dihedral angle at high pressure and temperatures, it is necessary to measure the relative frequency distributions of apparent dihedral angles between the quenched liquid metal and silicate grains for each experiment. Here I present a new imaging technique to visualize the distribution of liquid metal in silicate matrix in 3D by combination of focus ion beam (FIB) milling and high-resolution SEM image. The 3D volume rendering provides precise determination of the dihedral angle and quantitative measure of volume fraction and connectivity. I have conducted a series of experiments using mixtures of San Carlos olivine and Fe-S (10wt%S) metal with different metal-silicate ratios, up to 25 GPa and at temperatures above 1800C. High-quality 3D volume renderings were reconstructed from FIB serial sectioning and imaging with 10-nm slice thickness and 14-nm image resolution for each quenched sample. The unprecedented spatial resolution at nano scale allows detailed examination of textural features and precise determination of the dihedral angle as a function of pressure, temperature and composition. The 3D reconstruction also allows direct assessment of connectivity in multi-phase matrix, providing a new way to investigate the efficiency of metal percolation in a real silicate mantle.

Highly efficient enantioselective liquid–liquid extraction of 1,2-amino-alcohols using SPINOL based phosphoric acid hosts† †Electronic supplementary information (ESI) available: Experimental data regarding the synthesis the hosts as well as procedures and raw data and for ELLE experiments. See DOI: 10.1039/c7sc02783d Click here for additional data file.

PubMed Central

Pinxterhuis, Erik B.; Gualtierotti, Jean-Baptiste; Heeres, Hero J.

2017-01-01

Access to enantiopure compounds on large scale in an environmentally friendly and cost-efficient manner remains one of the greatest challenges in chemistry. Resolution of racemates using enantioselective liquid–liquid extraction has great potential to meet that challenge. However, a relatively feeble understanding of the chemical principles and physical properties behind this technique has hampered the development of hosts possessing sufficient resolving power for their application to large scale processes. Herein we present, employing the previously untested SPINOL based phosphoric acids host family, an in depths study of the parameters affecting the efficiency of the resolution of amino-alcohols in the optic of further understanding the core principles behind ELLE. We have systematically investigated the dependencies of the enantioselection by parameters such as the choice of solvent, the temperature, as well as the pH and bring to light many previously unsuspected and highly intriguing interactions. Furthermore, utilizing these new insights to our advantage, we developed novel, highly efficient, extraction and resolving protocols which provide remarkable levels of enantioselectivity. It was shown that the extraction is catalytic in host by demonstrating transport in a U-tube and finally it was demonstrated how the solvent dependency could be exploited in an unprecedented triphasic resolution system. PMID:28989671

Single-shot and single-sensor high/super-resolution microwave imaging based on metasurface

PubMed Central

Wang, Libo; Li, Lianlin; Li, Yunbo; Zhang, Hao Chi; Cui, Tie Jun

2016-01-01

Real-time high-resolution (including super-resolution) imaging with low-cost hardware is a long sought-after goal in various imaging applications. Here, we propose broadband single-shot and single-sensor high-/super-resolution imaging by using a spatio-temporal dispersive metasurface and an imaging reconstruction algorithm. The metasurface with spatio-temporal dispersive property ensures the feasibility of the single-shot and single-sensor imager for super- and high-resolution imaging, since it can convert efficiently the detailed spatial information of the probed object into one-dimensional time- or frequency-dependent signal acquired by a single sensor fixed in the far-field region. The imaging quality can be improved by applying a feature-enhanced reconstruction algorithm in post-processing, and the desired imaging resolution is related to the distance between the object and metasurface. When the object is placed in the vicinity of the metasurface, the super-resolution imaging can be realized. The proposed imaging methodology provides a unique means to perform real-time data acquisition, high-/super-resolution images without employing expensive hardware (e.g. mechanical scanner, antenna array, etc.). We expect that this methodology could make potential breakthroughs in the areas of microwave, terahertz, optical, and even ultrasound imaging. PMID:27246668

Flexible Neural Electrode Array Based-on Porous Graphene for Cortical Microstimulation and Sensing

NASA Astrophysics Data System (ADS)

Lu, Yichen; Lyu, Hongming; Richardson, Andrew G.; Lucas, Timothy H.; Kuzum, Duygu

2016-09-01

Neural sensing and stimulation have been the backbone of neuroscience research, brain-machine interfaces and clinical neuromodulation therapies for decades. To-date, most of the neural stimulation systems have relied on sharp metal microelectrodes with poor electrochemical properties that induce extensive damage to the tissue and significantly degrade the long-term stability of implantable systems. Here, we demonstrate a flexible cortical microelectrode array based on porous graphene, which is capable of efficient electrophysiological sensing and stimulation from the brain surface, without penetrating into the tissue. Porous graphene electrodes show superior impedance and charge injection characteristics making them ideal for high efficiency cortical sensing and stimulation. They exhibit no physical delamination or degradation even after 1 million biphasic stimulation cycles, confirming high endurance. In in vivo experiments with rodents, same array is used to sense brain activity patterns with high spatio-temporal resolution and to control leg muscles with high-precision electrical stimulation from the cortical surface. Flexible porous graphene array offers a minimally invasive but high efficiency neuromodulation scheme with potential applications in cortical mapping, brain-computer interfaces, treatment of neurological disorders, where high resolution and simultaneous recording and stimulation of neural activity are crucial.

Conflict Resolution for Wind-Optimal Aircraft Trajectories in North Atlantic Oceanic Airspace with Wind Uncertainties

NASA Technical Reports Server (NTRS)

Rodionova, Olga; Sridhar, Banavar; Ng, Hok K.

2016-01-01

Air traffic in the North Atlantic oceanic airspace (NAT) experiences very strong winds caused by jet streams. Flying wind-optimal trajectories increases individual flight efficiency, which is advantageous when operating in the NAT. However, as the NAT is highly congested during peak hours, a large number of potential conflicts between flights are detected for the sets of wind-optimal trajectories. Conflict resolution performed at the strategic level of flight planning can significantly reduce the airspace congestion. However, being completed far in advance, strategic planning can only use predicted environmental conditions that may significantly differ from the real conditions experienced further by aircraft. The forecast uncertainties result in uncertainties in conflict prediction, and thus, conflict resolution becomes less efficient. This work considers wind uncertainties in order to improve the robustness of conflict resolution in the NAT. First, the influence of wind uncertainties on conflict prediction is investigated. Then, conflict resolution methods accounting for wind uncertainties are proposed.

Performance modeling of terahertz (THz) and millimeter waves (mmW) pupil plane imaging

NASA Astrophysics Data System (ADS)

Mohammadian, Nafiseh; Furxhi, Orges; Zhang, Lei; Offermans, Peter; Ghazi, Galia; Driggers, Ronald

2018-05-01

Terahertz- (THz) and millimeter-wave sensors are becoming more important in industrial, security, medical, and defense applications. A major problem in these sensing areas is the resolution, sensitivity, and visual acuity of the imaging systems. There are different fundamental parameters in designing a system that have significant effects on the imaging performance. The performance of THz systems can be discussed in terms of two characteristics: sensitivity and spatial resolution. New approaches for design and manufacturing of THz imagers are a vital basis for developing future applications. Photonics solutions have been at the technological forefront in THz band applications. A single scan antenna does not provide reasonable resolution, sensitivity, and speed. An effective approach to imaging is placing a high-performance antenna in a two-dimensional antenna array to achieve higher radiation efficiency and higher resolution in the imaging systems. Here, we present the performance modeling of a pupil plane imaging system to find the resolution and sensitivity efficiency of the imaging system.

Rayleigh-wave dispersive energy imaging using a high-resolution linear radon transform

USGS Publications Warehouse

Luo, Y.; Xia, J.; Miller, R.D.; Xu, Y.; Liu, J.; Liu, Q.

2008-01-01

Multichannel Analysis of Surface Waves (MASW) analysis is an efficient tool to obtain the vertical shear-wave profile. One of the key steps in the MASW method is to generate an image of dispersive energy in the frequency-velocity domain, so dispersion curves can be determined by picking peaks of dispersion energy. In this paper, we propose to image Rayleigh-wave dispersive energy by high-resolution linear Radon transform (LRT). The shot gather is first transformed along the time direction to the frequency domain and then the Rayleigh-wave dispersive energy can be imaged by high-resolution LRT using a weighted preconditioned conjugate gradient algorithm. Synthetic data with a set of linear events are presented to show the process of generating dispersive energy. Results of synthetic and real-world examples demonstrate that, compared with the slant stacking algorithm, high-resolution LRT can improve the resolution of images of dispersion energy by more than 50%. ?? Birkhaueser 2008.

Blackbody absorption efficiencies for six lamp pumped Nd laser materials

NASA Technical Reports Server (NTRS)

Cross, Patricia L.; Barnes, Norman P.; Skolaut, Milton W., Jr.; Storm, Mark E.

1990-01-01

Utilizing high resolution spectra, the absorption efficiencies for six Nd laser materials were calculated as functions of the effective blackbody temperature of the lamp and laser crystal size. The six materials were Nd:YAG, Nd:YLF, Nd:Q-98 Glass, Nd:YVO4, Nd:BEL, and Nd:Cr:GSGG. Under the guidelines of this study, Nd:Cr:GSGG's absorption efficiency is twice the absorption efficiency of any of the other laser materials.

A direct method for unfolding the resolution function from measurements of neutron induced reactions

NASA Astrophysics Data System (ADS)

Žugec, P.; Colonna, N.; Sabate-Gilarte, M.; Vlachoudis, V.; Massimi, C.; Lerendegui-Marco, J.; Stamatopoulos, A.; Bacak, M.; Warren, S. G.; n TOF Collaboration

2017-12-01

The paper explores the numerical stability and the computational efficiency of a direct method for unfolding the resolution function from the measurements of the neutron induced reactions. A detailed resolution function formalism is laid out, followed by an overview of challenges present in a practical implementation of the method. A special matrix storage scheme is developed in order to facilitate both the memory management of the resolution function matrix, and to increase the computational efficiency of the matrix multiplication and decomposition procedures. Due to its admirable computational properties, a Cholesky decomposition is at the heart of the unfolding procedure. With the smallest but necessary modification of the matrix to be decomposed, the method is successfully applied to system of 105 × 105. However, the amplification of the uncertainties during the direct inversion procedures limits the applicability of the method to high-precision measurements of neutron induced reactions.

Super-resolution photon-efficient imaging by nanometric double-helix point spread function localization of emitters (SPINDLE)

PubMed Central

Grover, Ginni; DeLuca, Keith; Quirin, Sean; DeLuca, Jennifer; Piestun, Rafael

2012-01-01

Super-resolution imaging with photo-activatable or photo-switchable probes is a promising tool in biological applications to reveal previously unresolved intra-cellular details with visible light. This field benefits from developments in the areas of molecular probes, optical systems, and computational post-processing of the data. The joint design of optics and reconstruction processes using double-helix point spread functions (DH-PSF) provides high resolution three-dimensional (3D) imaging over a long depth-of-field. We demonstrate for the first time a method integrating a Fisher information efficient DH-PSF design, a surface relief optical phase mask, and an optimal 3D localization estimator. 3D super-resolution imaging using photo-switchable dyes reveals the 3D microtubule network in mammalian cells with localization precision approaching the information theoretical limit over a depth of 1.2 µm. PMID:23187521

ACS Data Handbook v.6.0

NASA Astrophysics Data System (ADS)

Gonzaga, S.; et al.

2011-03-01

ACS was designed to provide a deep, wide-field survey capability from the visible to near-IR using the Wide Field Camera (WFC), high resolution imaging from the near-UV to near-IR with the now-defunct High Resolution Camera (HRC), and solar-blind far-UV imaging using the Solar Blind Camera (SBC). The discovery efficiency of ACS's Wide Field Channel (i.e., the product of WFC's field of view and throughput) is 10 times greater than that of WFPC2. The failure of ACS's CCD electronics in January 2007 brought a temporary halt to CCD imaging until Servicing Mission 4 in May 2009, when WFC functionality was restored. Unfortunately, the high-resolution optical imaging capability of HRC was not recovered.

High efficiency CsI(Tl)/HgI{sub 2} gamma ray spectrometers

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

Wang, Y.J.; Patt, B.E.; Iwanczyk, J.S.

CsI(Tl)/HgI{sub 2} gamma-ray spectrometers have been constructed using 0.5 inch diameter detectors which show excellent energy resolution: 4.58% FWHM for 662 keV {sup 137}Cs gamma-ray photons. Further efforts have been focused on optimization of larger size ({ge} 1 inch diameter) detector structures and improvement of low noise electronics. In order to take full advantage of scintillation detectors for high energy gamma-rays, larger scintillators are always preferred for their higher detection efficiencies. However, the larger capacitance and higher dark current caused by the larger size of the detector could result in a higher FWHM resolution. Also, the increased probability of includingmore » nonuniformities in larger pieces of crystals makes it more difficult to obtain the high resolutions one obtains from small detectors. Thus for very large volume scintillators, it may be necessary to employ a photodiode (PD) with a sensitive area smaller than the cross-section of the scintillator. Monte Carlo simulations of the light collection for various tapered scintillator/PD configuration were performed in order to find those geometries which resulted in the best light collection. According to the simulation results, scintillators with the most favorable geometry, the conical frustum, have been fabricated and evaluated. The response of a large conical frustum (top-2 inch, bottom-1 inch, 2 inch high) CsI(Tl) scintillator coupled with a 1 inch HgI{sub 2} PD was measured. The energy resolution of the 662 keV peak was 5.57%. The spectrum shows much higher detection efficiency than those from smaller scintillators, i.e., much higher peak-to-Compton ratio in the spectrum.« less

Expanding the detection efficiency of silicon drift detectors

NASA Astrophysics Data System (ADS)

Schlosser, D. M.; Lechner, P.; Lutz, G.; Niculae, A.; Soltau, H.; Strüder, L.; Eckhardt, R.; Hermenau, K.; Schaller, G.; Schopper, F.; Jaritschin, O.; Liebel, A.; Simsek, A.; Fiorini, C.; Longoni, A.

2010-12-01

To expand the detection efficiency Silicon Drift Detectors (SDDs) with various customized radiation entrance windows, optimized detector areas and geometries have been developed. Optimum values for energy resolution, peak to background ratio (P/B) and high count rate capability support the development. Detailed results on sensors optimized for light element detection down to Boron or even lower will be reported. New developments for detecting medium and high X-ray energies by increasing the effective detector thickness will be presented. Gamma-ray detectors consisting of a SDD coupled to scintillators like CsI(Tl) and LaBr 3(Ce) have been examined. Results of the energy resolution for the 137Cs 662 keV line and the light yield (LY) of such detector systems will be reported.

Nowcasting for a high-resolution weather radar network

NASA Astrophysics Data System (ADS)

Ruzanski, Evan

Short-term prediction (nowcasting) of high-impact weather events can lead to significant improvement in warnings and advisories and is of great practical importance. Nowcasting using weather radar reflectivity data has been shown to be particularly useful. The Collaborative Adaptive Sensing of the Atmosphere (CASA) radar network provides high-resolution reflectivity data amenable to producing valuable nowcasts. The high-resolution nature of CASA data requires the use of an efficient nowcasting approach, which necessitated the development of the Dynamic Adaptive Radar Tracking of Storms (DARTS) and sinc kernel-based advection nowcasting methodology. This methodology was implemented operationally in the CASA Distributed Collaborative Adaptive Sensing (DCAS) system in a robust and efficient manner necessitated by the high-resolution nature of CASA data and distributed nature of the environment in which the nowcasting system operates. Nowcasts up to 10 min to support emergency manager decision-making and 1--5 min to steer the CASA radar nodes to better observe the advecting storm patterns for forecasters and researchers are currently provided by this system. Results of nowcasting performance during the 2009 CASA IP experiment are presented. Additionally, currently state-of-the-art scale-based filtering methods were adapted and evaluated for use in the CASA DCAS to provide a scale-based analysis of nowcasting. DARTS was also incorporated in the Weather Support to Deicing Decision Making system to provide more accurate and efficient snow water equivalent nowcasts for aircraft deicing decision support relative to the radar-based nowcasting method currently used in the operational system. Results of an evaluation using data collected from 2007--2008 by the Weather Service Radar-1988 Doppler (WSR-88D) located near Denver, Colorado, and the National Center for Atmospheric Research Marshall Test Site near Boulder, Colorado, are presented. DARTS was also used to study the short-term predictability of precipitation patterns depicted by high-resolution reflectivity data observed at microalpha (0.2--2 km) to mesobeta (20--200 km) scales by the CASA radar network. Additionally, DARTS was used to investigate the performance of nowcasting rainfall fields derived from specific differential phase estimates, which have been shown to provide more accurate and robust rainfall estimates compared to those made from radar reflectivity data.

Apertureless near-field/far-field CW two-photon microscope for biological and material imaging and spectroscopic applications.

PubMed

Nowak, Derek B; Lawrence, A J; Sánchez, Erik J

2010-12-10

We present the development of a versatile spectroscopic imaging tool to allow for imaging with single-molecule sensitivity and high spatial resolution. The microscope allows for near-field and subdiffraction-limited far-field imaging by integrating a shear-force microscope on top of a custom inverted microscope design. The instrument has the ability to image in ambient conditions with optical resolutions on the order of tens of nanometers in the near field. A single low-cost computer controls the microscope with a field programmable gate array data acquisition card. High spatial resolution imaging is achieved with an inexpensive CW multiphoton excitation source, using an apertureless probe and simplified optical pathways. The high-resolution, combined with high collection efficiency and single-molecule sensitive optical capabilities of the microscope, are demonstrated with a low-cost CW laser source as well as a mode-locked laser source.

Wide-aperture aspherical lens for high-resolution terahertz imaging

NASA Astrophysics Data System (ADS)

Chernomyrdin, Nikita V.; Frolov, Maxim E.; Lebedev, Sergey P.; Reshetov, Igor V.; Spektor, Igor E.; Tolstoguzov, Viktor L.; Karasik, Valeriy E.; Khorokhorov, Alexei M.; Koshelev, Kirill I.; Schadko, Aleksander O.; Yurchenko, Stanislav O.; Zaytsev, Kirill I.

2017-01-01

In this paper, we introduce wide-aperture aspherical lens for high-resolution terahertz (THz) imaging. The lens has been designed and analyzed by numerical methods of geometrical optics and electrodynamics. It has been made of high-density polyethylene by shaping at computer-controlled lathe and characterized using a continuous-wave THz imaging setup based on a backward-wave oscillator and Golay detector. The concept of image contrast has been implemented to estimate image quality. According to the experimental data, the lens allows resolving two points spaced at 0.95λ distance with a contrast of 15%. To highlight high resolution in the THz images, the wide-aperture lens has been employed for studying printed electronic circuit board containing sub-wavelength-scale elements. The observed results justify the high efficiency of the proposed lens design.

High-intensity xenon plasma discharge lamp for bulk-sensitive high-resolution photoemission spectroscopy.

PubMed

Souma, S; Sato, T; Takahashi, T; Baltzer, P

2007-12-01

We have developed a highly brilliant xenon (Xe) discharge lamp operated by microwave-induced electron cyclotron resonance (ECR) for ultrahigh-resolution bulk-sensitive photoemission spectroscopy (PES). We observed at least eight strong radiation lines from neutral or singly ionized Xe atoms in the energy region of 8.4-10.7 eV. The photon flux of the strongest Xe I resonance line at 8.437 eV is comparable to that of the He Ialpha line (21.218 eV) from the He-ECR discharge lamp. Stable operation for more than 300 h is achieved by efficient air-cooling of a ceramic tube in the resonance cavity. The high bulk sensitivity and high-energy resolution of PES using the Xe lines are demonstrated for some typical materials.

Beamline P02.1 at PETRA III for high-resolution and high-energy powder diffraction

PubMed Central

Dippel, Ann-Christin; Liermann, Hanns-Peter; Delitz, Jan Torben; Walter, Peter; Schulte-Schrepping, Horst; Seeck, Oliver H.; Franz, Hermann

2015-01-01

Powder X-ray diffraction techniques largely benefit from the superior beam quality provided by high-brilliance synchrotron light sources in terms of photon flux and angular resolution. The High Resolution Powder Diffraction Beamline P02.1 at the storage ring PETRA III (DESY, Hamburg, Germany) combines these strengths with the power of high-energy X-rays for materials research. The beamline is operated at a fixed photon energy of 60 keV (0.207 Å wavelength). A high-resolution monochromator generates the highly collimated X-ray beam of narrow energy bandwidth. Classic crystal structure determination in reciprocal space at standard and non-ambient conditions are an essential part of the scientific scope as well as total scattering analysis using the real space information of the pair distribution function. Both methods are complemented by in situ capabilities with time-resolution in the sub-second regime owing to the high beam intensity and the advanced detector technology for high-energy X-rays. P02.1’s efficiency in solving chemical and crystallographic problems is illustrated by presenting key experiments that were carried out within these fields during the early stage of beamline operation. PMID:25931084

A hybrid color mapping approach to fusing MODIS and Landsat images for forward prediction

USDA-ARS?s Scientific Manuscript database

We present a new, simple, and efficient approach to fusing MODIS and Landsat images. It is well known that MODIS images have high temporal resolution and low spatial resolution whereas Landsat images are just the opposite. Similar to earlier approaches, our goal is to fuse MODIS and Landsat images t...

Application of the MacCormack scheme to overland flow routing for high-spatial resolution distributed hydrological model

NASA Astrophysics Data System (ADS)

Zhang, Ling; Nan, Zhuotong; Liang, Xu; Xu, Yi; Hernández, Felipe; Li, Lianxia

2018-03-01

Although process-based distributed hydrological models (PDHMs) are evolving rapidly over the last few decades, their extensive applications are still challenged by the computational expenses. This study attempted, for the first time, to apply the numerically efficient MacCormack algorithm to overland flow routing in a representative high-spatial resolution PDHM, i.e., the distributed hydrology-soil-vegetation model (DHSVM), in order to improve its computational efficiency. The analytical verification indicates that both the semi and full versions of the MacCormack schemes exhibit robust numerical stability and are more computationally efficient than the conventional explicit linear scheme. The full-version outperforms the semi-version in terms of simulation accuracy when a same time step is adopted. The semi-MacCormack scheme was implemented into DHSVM (version 3.1.2) to solve the kinematic wave equations for overland flow routing. The performance and practicality of the enhanced DHSVM-MacCormack model was assessed by performing two groups of modeling experiments in the Mercer Creek watershed, a small urban catchment near Bellevue, Washington. The experiments show that DHSVM-MacCormack can considerably improve the computational efficiency without compromising the simulation accuracy of the original DHSVM model. More specifically, with the same computational environment and model settings, the computational time required by DHSVM-MacCormack can be reduced to several dozen minutes for a simulation period of three months (in contrast with one day and a half by the original DHSVM model) without noticeable sacrifice of the accuracy. The MacCormack scheme proves to be applicable to overland flow routing in DHSVM, which implies that it can be coupled into other PHDMs for watershed routing to either significantly improve their computational efficiency or to make the kinematic wave routing for high resolution modeling computational feasible.

Velocity map imaging using an in-vacuum pixel detector

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

Gademann, Georg; Huismans, Ymkje; Gijsbertsen, Arjan

The use of a new type in-vacuum pixel detector in velocity map imaging (VMI) is introduced. The Medipix2 and Timepix semiconductor pixel detectors (256x256 square pixels, 55x55 {mu}m{sup 2}) are well suited for charged particle detection. They offer high resolution, low noise, and high quantum efficiency. The Medipix2 chip allows double energy discrimination by offering a low and a high energy threshold. The Timepix detector allows to record the incidence time of a particle with a temporal resolution of 10 ns and a dynamic range of 160 {mu}s. Results of the first time application of the Medipix2 detector to VMImore » are presented, investigating the quantum efficiency as well as the possibility to operate at increased background pressure in the vacuum chamber.« less

High-speed and high-efficiency travelling wave single-photon detectors embedded in nanophotonic circuits

PubMed Central

Pernice, W.H.P.; Schuck, C.; Minaeva, O.; Li, M.; Goltsman, G.N.; Sergienko, A.V.; Tang, H.X.

2012-01-01

Ultrafast, high-efficiency single-photon detectors are among the most sought-after elements in modern quantum optics and quantum communication. However, imperfect modal matching and finite photon absorption rates have usually limited their maximum attainable detection efficiency. Here we demonstrate superconducting nanowire detectors atop nanophotonic waveguides, which enable a drastic increase of the absorption length for incoming photons. This allows us to achieve high on-chip single-photon detection efficiency up to 91% at telecom wavelengths, repeatable across several fabricated chips. We also observe remarkably low dark count rates without significant compromise of the on-chip detection efficiency. The detectors are fully embedded in scalable silicon photonic circuits and provide ultrashort timing jitter of 18 ps. Exploiting this high temporal resolution, we demonstrate ballistic photon transport in silicon ring resonators. Our direct implementation of a high-performance single-photon detector on chip overcomes a major barrier in integrated quantum photonics. PMID:23271658

MSE spectrograph optical design: a novel pupil slicing technique

NASA Astrophysics Data System (ADS)

Spanò, P.

2014-07-01

The Maunakea Spectroscopic Explorer shall be mainly devoted to perform deep, wide-field, spectroscopic surveys at spectral resolutions from ~2000 to ~20000, at visible and near-infrared wavelengths. Simultaneous spectral coverage at low resolution is required, while at high resolution only selected windows can be covered. Moreover, very high multiplexing (3200 objects) must be obtained at low resolution. At higher resolutions a decreased number of objects (~800) can be observed. To meet such high demanding requirements, a fiber-fed multi-object spectrograph concept has been designed by pupil-slicing the collimated beam, followed by multiple dispersive and camera optics. Different resolution modes are obtained by introducing anamorphic lenslets in front of the fiber arrays. The spectrograph is able to switch between three resolution modes (2000, 6500, 20000) by removing the anamorphic lenses and exchanging gratings. Camera lenses are fixed in place to increase stability. To enhance throughput, VPH first-order gratings has been preferred over echelle gratings. Moreover, throughput is kept high over all wavelength ranges by splitting light into more arms by dichroic beamsplitters and optimizing efficiency for each channel by proper selection of glass materials, coatings, and grating parameters.

Adaptive mesh strategies for the spectral element method

NASA Technical Reports Server (NTRS)

Mavriplis, Catherine

1992-01-01

An adaptive spectral method was developed for the efficient solution of time dependent partial differential equations. Adaptive mesh strategies that include resolution refinement and coarsening by three different methods are illustrated on solutions to the 1-D viscous Burger equation and the 2-D Navier-Stokes equations for driven flow in a cavity. Sharp gradients, singularities, and regions of poor resolution are resolved optimally as they develop in time using error estimators which indicate the choice of refinement to be used. The adaptive formulation presents significant increases in efficiency, flexibility, and general capabilities for high order spectral methods.

Large gamma-ray detector arrays and electromagnetic separators

NASA Astrophysics Data System (ADS)

Lee, I.-Yang

2013-12-01

The use of large gamma-ray detector arrays with electromagnetic separators is a powerful combination. Various types of gamma-ray detectors have been used; some provide high detector efficiency such as scintillation detector array, others use Ge detectors for good energy resolution, and recently developed Ge energy tracking arrays gives both high peak-to-background ratio and position resolution. Similarly, different types of separators were used to optimize the performance under different experimental requirements and conditions. For example, gas-filled separators were used in heavy element studies for their large efficiency and beam rejection factor. Vacuum separators with good isotope resolution were used in transfer and fragmentation reactions for the study of nuclei far from stability. This paper presents results from recent experiments using gamma-ray detector arrays in combination with electromagnetic separators, and discusses the physics opportunities provided by these instruments. In particular, we review the performance of the instruments currently in use, and discuss the requirements of instruments for future radioactive beam accelerator facilities.

High-Resolution Protein Structure Determination by Serial Femtosecond Crystallography

PubMed Central

Boutet, Sébastien; Lomb, Lukas; Williams, Garth J.; Barends, Thomas R. M.; Aquila, Andrew; Doak, R. Bruce; Weierstall, Uwe; DePonte, Daniel P.; Steinbrener, Jan; Shoeman, Robert L.; Messerschmidt, Marc; Barty, Anton; White, Thomas A.; Kassemeyer, Stephan; Kirian, Richard A.; Seibert, M. Marvin; Montanez, Paul A.; Kenney, Chris; Herbst, Ryan; Hart, Philip; Pines, Jack; Haller, Gunther; Gruner, Sol M.; Philipp, Hugh T.; Tate, Mark W.; Hromalik, Marianne; Koerner, Lucas J.; van Bakel, Niels; Morse, John; Ghonsalves, Wilfred; Arnlund, David; Bogan, Michael J.; Caleman, Carl; Fromme, Raimund; Hampton, Christina Y.; Hunter, Mark S.; Johansson, Linda C.; Katona, Gergely; Kupitz, Christopher; Liang, Mengning; Martin, Andrew V.; Nass, Karol; Redecke, Lars; Stellato, Francesco; Timneanu, Nicusor; Wang, Dingjie; Zatsepin, Nadia A.; Schafer, Donald; Defever, James; Neutze, Richard; Fromme, Petra; Spence, John C. H.; Chapman, Henry N.; Schlichting, Ilme

2013-01-01

Structure determination of proteins and other macromolecules has historically required the growth of high-quality crystals sufficiently large to diffract x-rays efficiently while withstanding radiation damage. We applied serial femtosecond crystallography (SFX) using an x-ray free-electron laser (XFEL) to obtain high-resolution structural information from microcrystals (less than 1 micrometer by 1 micrometer by 3 micrometers) of the well-characterized model protein lysozyme. The agreement with synchrotron data demonstrates the immediate relevance of SFX for analyzing the structure of the large group of difficult-to-crystallize molecules. PMID:22653729

High resolution laser beam induced current images under trichromatic laser radiation: approximation to the solar irradiation.

PubMed

Navas, F J; Alcántara, R; Fernández-Lorenzo, C; Martín-Calleja, J

2010-03-01

A laser beam induced current (LBIC) map of a photoactive surface is a very useful tool when it is necessary to study the spatial variability of properties such as photoconverter efficiency or factors connected with the recombination of carriers. Obtaining high spatial resolution LBIC maps involves irradiating the photoactive surface with a photonic beam with Gaussian power distribution and with a low dispersion coefficient. Laser emission fulfils these characteristics, but against it is the fact that it is highly monochromatic and therefore has a spectral distribution different to solar emissions. This work presents an instrumental system and procedure to obtain high spatial resolution LBIC maps in conditions approximating solar irradiation. The methodology developed consists of a trichromatic irradiation system based on three sources of laser excitation with emission in the red, green, and blue zones of the electromagnetic spectrum. The relative irradiation powers are determined by either solar spectrum distribution or Planck's emission formula which provides information approximate to the behavior of the system if it were under solar irradiation. In turn, an algorithm and a procedure have been developed to be able to form images based on the scans performed by the three lasers, providing information about the photoconverter efficiency of photovoltaic devices under the irradiation conditions used. This system has been checked with three photosensitive devices based on three different technologies: a commercial silicon photodiode, a commercial photoresistor, and a dye-sensitized solar cell. These devices make it possible to check how the superficial quantum efficiency has areas dependent upon the excitation wavelength while it has been possible to measure global incident photon-to-current efficiency values approximating those that would be obtained under irradiation conditions with sunlight.

Coupling HPLC-SPE-NMR with a microplate-based high-resolution antioxidant assay for efficient analysis of antioxidants in food--validation and proof-of-concept study with caper buds.

PubMed

Wiese, Stefanie; Wubshet, Sileshi G; Nielsen, John; Staerk, Dan

2013-12-15

This work describes the coupling of a microplate-based antioxidant assay with a hyphenated system consisting of high-performance liquid chromatography-solid-phase extraction-nuclear magnetic resonance spectroscopy, i.e., HPLC-SPE-NMR/high-resolution antioxidant assay, for the analysis of complex food extracts. The applicability of the microplate-based antioxidant assay for high-resolution screening of common food phenolics as well as parameters related to their trapping efficiency, elution behavior, and recovery on/from SPE cartridges are described. It was found that the microplate-based high-resolution antioxidant assay is an attractive and easy implementable alternative to direct on-line screening methods. Furthermore, it was shown that Resin SH and Resin GP SPE material are superior to RP C18HD for trapping of phenolic compounds. Proof-of-concept study was performed with caper bud extract, revealing the most important antioxidants to be quercetin, kaempferol, rutin, kaempferol-3-O-β-rutinoside and N(1),N(5),N(10)-triphenylpropenoyl spermidine amides. Targeted isolation of the latter, and comprehensive NMR experiments showed them to be N(1),N(10)-di-(E)-caffeoyl-N(5)-p-(E)-coumaroyl spermidine, N(1)-(E)-caffeoyl-N(5),N(10)-di-p-(E)-coumaroyl spermidine, N(10)-(E)-caffeoyl-N(1),N(5)-di-p-(E)-coumaroyl spermidine, and N(1),N(5),N(10)-tri-p-(E)-coumaroyl spermidine amides. Copyright © 2013 Elsevier Ltd. All rights reserved.

The STIS MAMA status: Current detector performance

NASA Technical Reports Server (NTRS)

Danks, A. C.; Joseph, C.; Bybee, R.; Argebright, V.; Abraham, J.; Kimble, R.; Woodgate, B.

1992-01-01

The STIS (Space Telescope Imaging Spectrograph) is a second generation Hubble instrument scheduled to fly in 1997. Through a variety of modes, the instrument will provide spectral resolutions from R approximately 50 in the objective spectroscopy mode to 100,000 in the high resolution echelle mode in the wavelength region from 115 to 1000 nm. In the UV the instrument employs two MAMA (Multimode Anode Microchannel plate Arrays) 1024 by 1024 pixel detectors, which provide high DQE (Detective Quantum Efficiency), and good dynamic range and resolution. The current progress and performance of these detectors are reported, illustrating that the technology is mature and that the performance is very close to flight requirements.

Performance of the EBIT calorimeter spectrometer

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

Porter, Frederick Scott; Gygax, John; Kelley, Richard L.

The EBIT calorimeter spectrometer (ECS) is a new high-resolution, broadband x-ray spectrometer that has recently been installed at the Electron Beam Ion Trap Facility (EBIT) at the Lawrence Livermore National Laboratory. The ECS is an entirely new production class spectrometer that replaces the XRS/EBIT spectrometer that has been operating at EBIT since 2000. The ECS utilizes a 32-pixel x-ray calorimeter array from the XRS instrument on the Suzaku x-ray observatory. Eighteen of the pixels are optimized for the 0.1-10 keV band and yield 4.5 eV full width at half maximum energy resolution and 95% quantum efficiency at 6 keV. Inmore » addition, the ECS includes 14 detector pixels that are optimized for the high-energy band with a bandpass from 0.5 to over 100 keV with 34 eV resolution and 32% quantum efficiency at 60 keV. The ECS detector array is operated at 50 mK using a five stage cryogenic system that is entirely automated. The instrument takes data continuously for over 65 h with a 2.5 h recycle time. The ECS is a nondispersive, broadband, highly efficient spectrometer that is one of the prime instruments at the EBIT facility. The instrument is used for studies of absolute cross sections, charge exchange recombination, and x-ray emission from nonequilibrium plasmas, among other measurements in our laboratory astrophysics program.« less

Broadband and high-efficiency vortex beam generator based on a hybrid helix array.

PubMed

Fang, Chaoqun; Wu, Chao; Gong, Zhijie; Zhao, Song; Sun, Anqi; Wei, Zeyong; Li, Hongqiang

2018-04-01

The vortex beam which carries the orbital angular momentum has versatile applications, such as high-resolution imaging, optical communications, and particle manipulation. Generating vortex beams with the Pancharatnam-Berry (PB) phase has drawn considerable attention for its unique spin-to-orbital conversion features. Despite the PB phase being frequency independent, an optical element with broadband high-efficiency circular polarization conversion feature is still needed for the broadband high-efficiency vortex beam generation. In this work, a broadband and high-efficiency vortex beam generator based on the PB phase is built with a hybrid helix array. Such devices can generate vortex beams with arbitrary topological charge. Moreover, vortex beams with opposite topological charge can be generated with an opposite handedness incident beam that propagates backward. The measured efficiency of our device is above 65% for a wide frequency range, with the relative bandwidth of 46.5%.

High Resolution PET with 250 micrometer LSO Detectors and Adaptive Zoom

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

Cherry, Simon R.; Qi, Jinyi

2012-01-08

There have been impressive improvements in the performance of small-animal positron emission tomography (PET) systems since their first development in the mid 1990s, both in terms of spatial resolution and sensitivity, which have directly contributed to the increasing adoption of this technology for a wide range of biomedical applications. Nonetheless, current systems still are largely dominated by the size of the scintillator elements used in the detector. Our research predicts that developing scintillator arrays with an element size of 250 {micro}m or smaller will lead to an image resolution of 500 {micro}m when using 18F- or 64Cu-labeled radiotracers, giving amore » factor of 4-8 improvement in volumetric resolution over the highest resolution research systems currently in existence. This proposal had two main objectives: (i) To develop and evaluate much higher resolution and efficiency scintillator arrays that can be used in the future as the basis for detectors in a small-animal PET scanner where the spatial resolution is dominated by decay and interaction physics rather than detector size. (ii) To optimize one such high resolution, high sensitivity detector and adaptively integrate it into the existing microPET II small animal PET scanner as a 'zoom-in' detector that provides higher spatial resolution and sensitivity in a limited region close to the detector face. The knowledge gained from this project will provide valuable information for building future PET systems with a complete ring of very high-resolution detector arrays and also lay the foundations for utilizing high-resolution detectors in combination with existing PET systems for localized high-resolution imaging.« less

The Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS)

NASA Technical Reports Server (NTRS)

Oegerle, William (Technical Monitor); Rabin, D.; Davila, J.; Thomas, R. J.; Engler, C.; Irish, S.; Keski-Kuha, R.; Novello, J.; Nowak, M.; Payne, L.;

Multipass holographic interferometer improves image resolution

NASA Technical Reports Server (NTRS)

Brooks, R. E.; Heflinger, L. O.

1970-01-01

Multipass holographic interferometer forms a hologram of high diffraction efficiency, and hence provides a bright and high contrast interferogram. It is used to study any effect which changes the index of refraction and to study surface deformations of a flat reflecting surface.

Ultraviolet observations of the gas phase abundances in the diffuse clouds toward Zeta Ophiuchi at 3.5 kilometers per second resolution

NASA Technical Reports Server (NTRS)

Savage, Blair D.; Cardelli, Jason A.; Sofia, Ulysses J.

1992-01-01

Goddard High Resolution Spectrograph echelle mode measurements at 3.5 km/s resolution are presented for interstellar absorption produced by C II, O I, Mg I, Mg II, Al III, P II, Cr II, Mn II, Fe II, Ni II, Cu II, Zn II, Ga II, Ge II, and Kr I. The absorption line measurements are converted into representations of apparent column density per unit velocity in order to study the multicomponent nature of the absorption. The high spectral resolution of the measurements allows a comparative study of gas phase abundances for many species in the absorbing clouds near -27 and -15 km/s with a typical precision of about 0.05 dex. The matter absorbing near -27 km/s is situated in the local interstellar medium and has log N(H I) of about 19.74. This absorption provides information about the modest 'base' depletion associated with the lower density interstellar medium. The depletion results suggest that accretion processes are operating interstellar clouds that exhibit similar depletion efficiencies for some elements but much higher depletion efficiencies for others.

High density FTA plates serve as efficient long-term sample storage for HLA genotyping.

PubMed

Lange, V; Arndt, K; Schwarzelt, C; Boehme, I; Giani, A S; Schmidt, A H; Ehninger, G; Wassmuth, R

2014-02-01

Storage of dried blood spots (DBS) on high-density FTA(®) plates could constitute an appealing alternative to frozen storage. However, it remains controversial whether DBS are suitable for high-resolution sequencing of human leukocyte antigen (HLA) alleles. Therefore, we extracted DNA from DBS that had been stored for up to 4 years, using six different methods. We identified those extraction methods that recovered sufficient high-quality DNA for reliable high-resolution HLA sequencing. Further, we confirmed that frozen whole blood samples that had been stored for several years can be transferred to filter paper without compromising HLA genotyping upon extraction. Concluding, DNA derived from high-density FTA(®) plates is suitable for high-resolution HLA sequencing, provided that appropriate extraction protocols are employed. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Ultrahigh-resolution optical coherence tomography with a fiber laser source at 1 microm.

PubMed

Lim, Hyungsik; Jiang, Yi; Wang, Yimin; Huang, Yu-Chih; Chen, Zhongping; Wise, Frank W

2005-05-15

We report a compact, high-power, fiber-based source for ultrahigh-resolution optical coherence tomography (OCT) near 1 microm. The practical source is based on a short-pulse, ytterbium-doped fiber laser and on generation of a continuum spectrum in a photonic crystal fiber. The broadband emission has an average power of 140 mW and offers an axial resolution of 2.1 microm in air (<1.6 microm in biological tissue). The generation of a broad bandwidth is robust and efficient. We demonstrate ultrahigh-resolution, time-domain OCT imaging of in vitro and in vivo biological tissues.

Rapid brain MRI acquisition techniques at ultra-high fields

PubMed Central

Setsompop, Kawin; Feinberg, David A.; Polimeni, Jonathan R.

2017-01-01

Ultra-high-field MRI provides large increases in signal-to-noise ratio as well as enhancement of several contrast mechanisms in both structural and functional imaging. Combined, these gains result in a substantial boost in contrast-to-noise ratio that can be exploited for higher spatial resolution imaging to extract finer-scale information about the brain. With increased spatial resolution, however, is a concurrent increased image encoding burden that can cause unacceptably long scan times for structural imaging and slow temporal sampling of the hemodynamic response in functional MRI—particularly when whole-brain imaging is desired. To address this issue, new directions of imaging technology development—such as the move from conventional 2D slice-by-slice imaging to more efficient Simultaneous MultiSlice (SMS) or MultiBand imaging (which can be viewed as “pseudo-3D” encoding) as well as full 3D imaging—have provided dramatic improvements in acquisition speed. Such imaging paradigms provide higher SNR efficiency as well as improved encoding efficiency. Moreover, SMS and 3D imaging can make better use of coil sensitivity information in multi-channel receiver arrays used for parallel imaging acquisitions through controlled aliasing in multiple spatial directions. This has enabled unprecedented acceleration factors of an order of magnitude or higher in these imaging acquisition schemes, with low image artifact levels and high SNR. Here we review the latest developments of SMS and 3D imaging methods and related technologies at ultra-high field for rapid high-resolution functional and structural imaging of the brain. PMID:26835884

Ultrafast secondary emission X-ray imaging detectors: A possible application to TRD

NASA Astrophysics Data System (ADS)

Akkerman, A.; Breskin, A.; Chechik, R.; Elkind, V.; Gibrekhterman, A.; Majewski, S.

1992-05-01

Fist high accuracy, X-ray imaging at high photon flux can be achieved when coupling thin solid convertors to gaseous electron multipliers, operating at low gas pressures. Secondary electrons emitted from the convertor foil are multiplied in several successive amplification elements. The obvious advantages of solid X-ray convertors, as compared to gaseous conversion, are the production of parallax-free images and the fast (subnanosecond) response. These X-ray detectors have many potential applications in basic and applied research. Of particular interest is the possibility of an efficient and ultrafast high resolution imaging of transition radiation (TR), with a reduced d E/d x background. We present experimental results on the operation of secondary emission X-ray (SEX) detectors, their detection efficiency, localization and time resolution. The experimental work is accompanied by mathematical modelling and computer simulation of transition radiation detectors (TRDs) based on CsI TR convertors.

Note: Tandem Kirkpatrick-Baez microscope with sixteen channels for high-resolution laser-plasma diagnostics

NASA Astrophysics Data System (ADS)

Yi, Shengzhen; Zhang, Zhe; Huang, Qiushi; Zhang, Zhong; Wang, Zhanshan; Wei, Lai; Liu, Dongxiao; Cao, Leifeng; Gu, Yuqiu

2018-03-01

Multi-channel Kirkpatrick-Baez (KB) microscopes, which have better resolution and collection efficiency than pinhole cameras, have been widely used in laser inertial confinement fusion to diagnose time evolution of the target implosion. In this study, a tandem multi-channel KB microscope was developed to have sixteen imaging channels with the precise control of spatial resolution and image intervals. This precise control was created using a coarse assembly of mirror pairs with high-accuracy optical prisms, followed by precise adjustment in real-time x-ray imaging experiments. The multilayers coated on the KB mirrors were designed to have substantially the same reflectivity to obtain a uniform brightness of different images for laser-plasma temperature analysis. The study provides a practicable method to achieve the optimum performance of the microscope for future high-resolution applications in inertial confinement fusion experiments.

Hi-C 2.0: An optimized Hi-C procedure for high-resolution genome-wide mapping of chromosome conformation.

PubMed

Belaghzal, Houda; Dekker, Job; Gibcus, Johan H

2017-07-01

Chromosome conformation capture-based methods such as Hi-C have become mainstream techniques for the study of the 3D organization of genomes. These methods convert chromatin interactions reflecting topological chromatin structures into digital information (counts of pair-wise interactions). Here, we describe an updated protocol for Hi-C (Hi-C 2.0) that integrates recent improvements into a single protocol for efficient and high-resolution capture of chromatin interactions. This protocol combines chromatin digestion and frequently cutting enzymes to obtain kilobase (kb) resolution. It also includes steps to reduce random ligation and the generation of uninformative molecules, such as unligated ends, to improve the amount of valid intra-chromosomal read pairs. This protocol allows for obtaining information on conformational structures such as compartment and topologically associating domains, as well as high-resolution conformational features such as DNA loops. Copyright © 2017 Elsevier Inc. All rights reserved.

High-resolution x-ray tomography using laboratory sources

NASA Astrophysics Data System (ADS)

Tkachuk, Andrei; Feser, Michael; Cui, Hongtao; Duewer, Fred; Chang, Hauyee; Yun, Wenbing

2006-08-01

X-ray computed tomography (XCT) is a powerful nondestructive 3D imaging technique, which enables the visualization of the three dimensional structure of complex, optically opaque samples. High resolution XCT using Fresnel zone plate lenses has been confined in the past to synchrotron radiation centers due to the need for a bright and intense source of x-rays. This confinement severely limits the availability and accessibility of x-ray microscopes and the wide proliferation of this methodology. We are describing a sub-50nm resolution XCT system operating at 8 keV in absorption and Zernike phase contrast mode based on a commercially available laboratory x-ray source. The system utilizes high-efficiency Fresnel zone plates with an outermost zone width of 35 nm and 700 nm structure height resulting in a current spatial resolution better than 50 nm. In addition to the technical description of the system and specifications, we present application examples in the semiconductor field.

Cross-correlation photothermal optical coherence tomography with high effective resolution.

PubMed

Tang, Peijun; Liu, Shaojie; Chen, Junbo; Yuan, Zhiling; Xie, Bingkai; Zhou, Jianhua; Tang, Zhilie

2017-12-01

We developed a cross-correlation photothermal optical coherence tomography (CC-PTOCT) system for photothermal imaging with high lateral and axial resolution. The CC-PTOCT system consists of a phase-sensitive OCT system, a modulated pumping laser, and a digital cross-correlator. The pumping laser was used to induce the photothermal effect in the sample, causing a slight phase modulation of the OCT signals. A spatial phase differentiation method was employed to reduce phase accumulation. The noise brought by the phase differentiation method and the strong background noise were suppressed efficiently by the cross-correlator, which was utilized to extract the photothermal signals from the modulated signals. Combining the cross-correlation technique with spatial phase differentiation can improve both lateral and axial resolution of the PTOCT imaging system. Clear photothermal images of blood capillaries of a mouse ear in vivo were successfully obtained with high lateral and axial resolution. The experimental results demonstrated that this system can enhance the effective transverse resolution, effective depth resolution, and contrast of the PTOCT image effectively, aiding the ongoing development of the accurate 3D functional imaging.

Hyperspectral and multispectral data fusion based on linear-quadratic nonnegative matrix factorization

NASA Astrophysics Data System (ADS)

Benhalouche, Fatima Zohra; Karoui, Moussa Sofiane; Deville, Yannick; Ouamri, Abdelaziz

2017-04-01

This paper proposes three multisharpening approaches to enhance the spatial resolution of urban hyperspectral remote sensing images. These approaches, related to linear-quadratic spectral unmixing techniques, use a linear-quadratic nonnegative matrix factorization (NMF) multiplicative algorithm. These methods begin by unmixing the observable high-spectral/low-spatial resolution hyperspectral and high-spatial/low-spectral resolution multispectral images. The obtained high-spectral/high-spatial resolution features are then recombined, according to the linear-quadratic mixing model, to obtain an unobservable multisharpened high-spectral/high-spatial resolution hyperspectral image. In the first designed approach, hyperspectral and multispectral variables are independently optimized, once they have been coherently initialized. These variables are alternately updated in the second designed approach. In the third approach, the considered hyperspectral and multispectral variables are jointly updated. Experiments, using synthetic and real data, are conducted to assess the efficiency, in spatial and spectral domains, of the designed approaches and of linear NMF-based approaches from the literature. Experimental results show that the designed methods globally yield very satisfactory spectral and spatial fidelities for the multisharpened hyperspectral data. They also prove that these methods significantly outperform the used literature approaches.

Photon-counting CT with silicon detectors: feasibility for pediatric imaging

NASA Astrophysics Data System (ADS)

Yveborg, Moa; Xu, Cheng; Fredenberg, Erik; Danielsson, Mats

2009-02-01

X-ray detectors made of crystalline silicon have several advantages including low dark currents, fast charge collection and high energy resolution. For high-energy x-rays, however, silicon suffers from its low atomic number, which might result in low detection efficiency, as well as low energy and spatial resolution due to Compton scattering. We have used a monte-carlo model to investigate the feasibility of a detector for pediatric CT with 30 to 40 mm of silicon using x-ray spectra ranging from 80 to 140 kVp. A detection efficiency of 0.74 was found at 80 kVp, provided the noise threshold could be set low. Scattered photons were efficiently blocked by a thin metal shielding between the detector units, and Compton scattering in the detector could be well separated from photo absorption at 80 kVp. Hence, the detector is feasible at low acceleration voltages, which is also suitable for pediatric imaging. We conclude that silicon detectors may be an alternative to other designs for this special case.

Hyperspectral imagery super-resolution by compressive sensing inspired dictionary learning and spatial-spectral regularization.

PubMed

Huang, Wei; Xiao, Liang; Liu, Hongyi; Wei, Zhihui

2015-01-19

Due to the instrumental and imaging optics limitations, it is difficult to acquire high spatial resolution hyperspectral imagery (HSI). Super-resolution (SR) imagery aims at inferring high quality images of a given scene from degraded versions of the same scene. This paper proposes a novel hyperspectral imagery super-resolution (HSI-SR) method via dictionary learning and spatial-spectral regularization. The main contributions of this paper are twofold. First, inspired by the compressive sensing (CS) framework, for learning the high resolution dictionary, we encourage stronger sparsity on image patches and promote smaller coherence between the learned dictionary and sensing matrix. Thus, a sparsity and incoherence restricted dictionary learning method is proposed to achieve higher efficiency sparse representation. Second, a variational regularization model combing a spatial sparsity regularization term and a new local spectral similarity preserving term is proposed to integrate the spectral and spatial-contextual information of the HSI. Experimental results show that the proposed method can effectively recover spatial information and better preserve spectral information. The high spatial resolution HSI reconstructed by the proposed method outperforms reconstructed results by other well-known methods in terms of both objective measurements and visual evaluation.

Interactive local super-resolution reconstruction of whole-body MRI mouse data: a pilot study with applications to bone and kidney metastases.

PubMed

Dzyubachyk, Oleh; Khmelinskii, Artem; Plenge, Esben; Kok, Peter; Snoeks, Thomas J A; Poot, Dirk H J; Löwik, Clemens W G M; Botha, Charl P; Niessen, Wiro J; van der Weerd, Louise; Meijering, Erik; Lelieveldt, Boudewijn P F

2014-01-01

In small animal imaging studies, when the locations of the micro-structures of interest are unknown a priori, there is a simultaneous need for full-body coverage and high resolution. In MRI, additional requirements to image contrast and acquisition time will often make it impossible to acquire such images directly. Recently, a resolution enhancing post-processing technique called super-resolution reconstruction (SRR) has been demonstrated to improve visualization and localization of micro-structures in small animal MRI by combining multiple low-resolution acquisitions. However, when the field-of-view is large relative to the desired voxel size, solving the SRR problem becomes very expensive, in terms of both memory requirements and computation time. In this paper we introduce a novel local approach to SRR that aims to overcome the computational problems and allow researchers to efficiently explore both global and local characteristics in whole-body small animal MRI. The method integrates state-of-the-art image processing techniques from the areas of articulated atlas-based segmentation, planar reformation, and SRR. A proof-of-concept is provided with two case studies involving CT, BLI, and MRI data of bone and kidney tumors in a mouse model. We show that local SRR-MRI is a computationally efficient complementary imaging modality for the precise characterization of tumor metastases, and that the method provides a feasible high-resolution alternative to conventional MRI.

High-resolution dynamic 31 P-MRSI using a low-rank tensor model.

PubMed

Ma, Chao; Clifford, Bryan; Liu, Yuchi; Gu, Yuning; Lam, Fan; Yu, Xin; Liang, Zhi-Pei

2017-08-01

To develop a rapid 31 P-MRSI method with high spatiospectral resolution using low-rank tensor-based data acquisition and image reconstruction. The multidimensional image function of 31 P-MRSI is represented by a low-rank tensor to capture the spatial-spectral-temporal correlations of data. A hybrid data acquisition scheme is used for sparse sampling, which consists of a set of "training" data with limited k-space coverage to capture the subspace structure of the image function, and a set of sparsely sampled "imaging" data for high-resolution image reconstruction. An explicit subspace pursuit approach is used for image reconstruction, which estimates the bases of the subspace from the "training" data and then reconstructs a high-resolution image function from the "imaging" data. We have validated the feasibility of the proposed method using phantom and in vivo studies on a 3T whole-body scanner and a 9.4T preclinical scanner. The proposed method produced high-resolution static 31 P-MRSI images (i.e., 6.9 × 6.9 × 10 mm 3 nominal resolution in a 15-min acquisition at 3T) and high-resolution, high-frame-rate dynamic 31 P-MRSI images (i.e., 1.5 × 1.5 × 1.6 mm 3 nominal resolution, 30 s/frame at 9.4T). Dynamic spatiospectral variations of 31 P-MRSI signals can be efficiently represented by a low-rank tensor. Exploiting this mathematical structure for data acquisition and image reconstruction can lead to fast 31 P-MRSI with high resolution, frame-rate, and SNR. Magn Reson Med 78:419-428, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Detection of sub-kilometer craters in high resolution planetary images using shape and texture features

NASA Astrophysics Data System (ADS)

Bandeira, Lourenço; Ding, Wei; Stepinski, Tomasz F.

2012-01-01

Counting craters is a paramount tool of planetary analysis because it provides relative dating of planetary surfaces. Dating surfaces with high spatial resolution requires counting a very large number of small, sub-kilometer size craters. Exhaustive manual surveys of such craters over extensive regions are impractical, sparking interest in designing crater detection algorithms (CDAs). As a part of our effort to design a CDA, which is robust and practical for planetary research analysis, we propose a crater detection approach that utilizes both shape and texture features to identify efficiently sub-kilometer craters in high resolution panchromatic images. First, a mathematical morphology-based shape analysis is used to identify regions in an image that may contain craters; only those regions - crater candidates - are the subject of further processing. Second, image texture features in combination with the boosting ensemble supervised learning algorithm are used to accurately classify previously identified candidates into craters and non-craters. The design of the proposed CDA is described and its performance is evaluated using a high resolution image of Mars for which sub-kilometer craters have been manually identified. The overall detection rate of the proposed CDA is 81%, the branching factor is 0.14, and the overall quality factor is 72%. This performance is a significant improvement over the previous CDA based exclusively on the shape features. The combination of performance level and computational efficiency offered by this CDA makes it attractive for practical application.

Multi-GPU Accelerated Admittance Method for High-Resolution Human Exposure Evaluation.

PubMed

Xiong, Zubiao; Feng, Shi; Kautz, Richard; Chandra, Sandeep; Altunyurt, Nevin; Chen, Ji

2015-12-01

A multi-graphics processing unit (GPU) accelerated admittance method solver is presented for solving the induced electric field in high-resolution anatomical models of human body when exposed to external low-frequency magnetic fields. In the solver, the anatomical model is discretized as a three-dimensional network of admittances. The conjugate orthogonal conjugate gradient (COCG) iterative algorithm is employed to take advantage of the symmetric property of the complex-valued linear system of equations. Compared against the widely used biconjugate gradient stabilized method, the COCG algorithm can reduce the solving time by 3.5 times and reduce the storage requirement by about 40%. The iterative algorithm is then accelerated further by using multiple NVIDIA GPUs. The computations and data transfers between GPUs are overlapped in time by using asynchronous concurrent execution design. The communication overhead is well hidden so that the acceleration is nearly linear with the number of GPU cards. Numerical examples show that our GPU implementation running on four NVIDIA Tesla K20c cards can reach 90 times faster than the CPU implementation running on eight CPU cores (two Intel Xeon E5-2603 processors). The implemented solver is able to solve large dimensional problems efficiently. A whole adult body discretized in 1-mm resolution can be solved in just several minutes. The high efficiency achieved makes it practical to investigate human exposure involving a large number of cases with a high resolution that meets the requirements of international dosimetry guidelines.

Imaging resolution and properties analysis of super resolution microscopy with parallel detection under different noise, detector and image restoration conditions

NASA Astrophysics Data System (ADS)

Yu, Zhongzhi; Liu, Shaocong; Sun, Shiyi; Kuang, Cuifang; Liu, Xu

2018-06-01

Parallel detection, which can use the additional information of a pinhole plane image taken at every excitation scan position, could be an efficient method to enhance the resolution of a confocal laser scanning microscope. In this paper, we discuss images obtained under different conditions and using different image restoration methods with parallel detection to quantitatively compare the imaging quality. The conditions include different noise levels and different detector array settings. The image restoration methods include linear deconvolution and pixel reassignment with Richard-Lucy deconvolution and with maximum-likelihood estimation deconvolution. The results show that the linear deconvolution share properties such as high-efficiency and the best performance under all different conditions, and is therefore expected to be of use for future biomedical routine research.

A micron resolution optical scanner for characterization of silicon detectors

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

Shukla, R. A.; Dugad, S. R., E-mail: dugad@cern.ch; Gopal, A. V.

2014-02-15

The emergence of high position resolution (∼10 μm) silicon detectors in recent times have highlighted the urgent need for the development of new automated optical scanners of micron level resolution suited for characterizing microscopic features of these detectors. More specifically, for the newly developed silicon photo-multipliers (SiPM) that are compact, possessing excellent photon detection efficiency with gain comparable to photo-multiplier tube. In a short time, since their invention the SiPMs are already being widely used in several high-energy physics and astrophysics experiments as the photon readout element. The SiPM is a high quantum efficiency, multi-pixel photon counting detector with fastmore » timing and high gain. The presence of a wide variety of photo sensitive silicon detectors with high spatial resolution requires their performance evaluation to be carried out by photon beams of very compact spot size. We have designed a high resolution optical scanner that provides a monochromatic focused beam on a target plane. The transverse size of the beam was measured by the knife-edge method to be 1.7 μm at 1 − σ level. Since the beam size was an order of magnitude smaller than the typical feature size of silicon detectors, this optical scanner can be used for selective excitation of these detectors. The design and operational details of the optical scanner, high precision programmed movement of target plane (0.1 μm) integrated with general purpose data acquisition system developed for recording static and transient response photo sensitive silicon detector are reported in this paper. Entire functionality of scanner is validated by using it for selective excitation of individual pixels in a SiPM and identifying response of active and dead regions within SiPM. Results from these studies are presented in this paper.« less

Monte Carlo simulation studies on scintillation detectors and image reconstruction of brain-phantom tumors in TOFPET

PubMed Central

Mondal, Nagendra Nath

2009-01-01

This study presents Monte Carlo Simulation (MCS) results of detection efficiencies, spatial resolutions and resolving powers of a time-of-flight (TOF) PET detector systems. Cerium activated Lutetium Oxyorthosilicate (Lu2SiO5: Ce in short LSO), Barium Fluoride (BaF2) and BriLanCe 380 (Cerium doped Lanthanum tri-Bromide, in short LaBr3) scintillation crystals are studied in view of their good time and energy resolutions and shorter decay times. The results of MCS based on GEANT show that spatial resolution, detection efficiency and resolving power of LSO are better than those of BaF2 and LaBr3, although it possesses inferior time and energy resolutions. Instead of the conventional position reconstruction method, newly established image reconstruction (talked about in the previous work) method is applied to produce high-tech images. Validation is a momentous step to ensure that this imaging method fulfills all purposes of motivation discussed by reconstructing images of two tumors in a brain phantom. PMID:20098551

High efficiency x-ray nanofocusing by the blazed stacking of binary zone plates

NASA Astrophysics Data System (ADS)

Mohacsi, I.; Karvinen, P.; Vartiainen, I.; Diaz, A.; Somogyi, A.; Kewish, C. M.; Mercere, P.; David, C.

2013-09-01

The focusing efficiency of binary Fresnel zone plate lenses is fundamentally limited and higher efficiency requires a multi step lens profile. To overcome the manufacturing problems of high resolution and high efficiency multistep zone plates, we investigate the concept of stacking two different binary zone plates in each other's optical near-field. We use a coarse zone plate with π phase shift and a double density fine zone plate with π/2 phase shift to produce an effective 4- step profile. Using a compact experimental setup with piezo actuators for alignment, we demonstrated 47.1% focusing efficiency at 6.5 keV using a pair of 500 μm diameter and 200 nm smallest zone width. Furthermore, we present a spatially resolved characterization method using multiple diffraction orders to identify manufacturing errors, alignment errors and pattern distortions and their effect on diffraction efficiency.

A Coarse-to-Fine Geometric Scale-Invariant Feature Transform for Large Size High Resolution Satellite Image Registration

PubMed Central

Chang, Xueli; Du, Siliang; Li, Yingying; Fang, Shenghui

2018-01-01

Large size high resolution (HR) satellite image matching is a challenging task due to local distortion, repetitive structures, intensity changes and low efficiency. In this paper, a novel matching approach is proposed for the large size HR satellite image registration, which is based on coarse-to-fine strategy and geometric scale-invariant feature transform (SIFT). In the coarse matching step, a robust matching method scale restrict (SR) SIFT is implemented at low resolution level. The matching results provide geometric constraints which are then used to guide block division and geometric SIFT in the fine matching step. The block matching method can overcome the memory problem. In geometric SIFT, with area constraints, it is beneficial for validating the candidate matches and decreasing searching complexity. To further improve the matching efficiency, the proposed matching method is parallelized using OpenMP. Finally, the sensing image is rectified to the coordinate of reference image via Triangulated Irregular Network (TIN) transformation. Experiments are designed to test the performance of the proposed matching method. The experimental results show that the proposed method can decrease the matching time and increase the number of matching points while maintaining high registration accuracy. PMID:29702589

Real-time haptic cutting of high-resolution soft tissues.

PubMed

Wu, Jun; Westermann, Rüdiger; Dick, Christian

2014-01-01

We present our systematic efforts in advancing the computational performance of physically accurate soft tissue cutting simulation, which is at the core of surgery simulators in general. We demonstrate a real-time performance of 15 simulation frames per second for haptic soft tissue cutting of a deformable body at an effective resolution of 170,000 finite elements. This is achieved by the following innovative components: (1) a linked octree discretization of the deformable body, which allows for fast and robust topological modifications of the simulation domain, (2) a composite finite element formulation, which thoroughly reduces the number of simulation degrees of freedom and thus enables to carefully balance simulation performance and accuracy, (3) a highly efficient geometric multigrid solver for solving the linear systems of equations arising from implicit time integration, (4) an efficient collision detection algorithm that effectively exploits the composition structure, and (5) a stable haptic rendering algorithm for computing the feedback forces. Considering that our method increases the finite element resolution for physically accurate real-time soft tissue cutting simulation by an order of magnitude, our technique has a high potential to significantly advance the realism of surgery simulators.

Isotopic composition analysis and age dating of uranium samples by high resolution gamma ray spectrometry

NASA Astrophysics Data System (ADS)

Apostol, A. I.; Pantelica, A.; Sima, O.; Fugaru, V.

2016-09-01

Non-destructive methods were applied to determine the isotopic composition and the time elapsed since last chemical purification of nine uranium samples. The applied methods are based on measuring gamma and X radiations of uranium samples by high resolution low energy gamma spectrometric system with planar high purity germanium detector and low background gamma spectrometric system with coaxial high purity germanium detector. The ;Multigroup γ-ray Analysis Method for Uranium; (MGAU) code was used for the precise determination of samples' isotopic composition. The age of the samples was determined from the isotopic ratio 214Bi/234U. This ratio was calculated from the analyzed spectra of each uranium sample, using relative detection efficiency. Special attention is paid to the coincidence summing corrections that have to be taken into account when performing this type of analysis. In addition, an alternative approach for the age determination using full energy peak efficiencies obtained by Monte Carlo simulations with the GESPECOR code is described.

Efficient generation and characterization of spectrally factorable biphotons.

PubMed

Chen, Changchen; Bo, Cao; Niu, Murphy Yuezhen; Xu, Feihu; Zhang, Zheshen; Shapiro, Jeffrey H; Wong, Franco N C

2017-04-03

Spectrally unentangled biphotons with high single-spatiotemporal-mode purity are highly desirable for many quantum information processing tasks. We generate biphotons with an inferred heralded-state spectral purity of 99%, the highest to date without any spectral filtering, by pulsed spontaneous parametric downconversion in a custom-fabricated periodically-poled KTiOPO₄ crystal under extended Gaussian phase-matching conditions. To efficiently characterize the joint spectral intensity of the generated biphotons at high spectral resolution, we employ a commercially available dispersion compensation module (DCM) with a dispersion equivalent to 100 km of standard optical fiber and with an insertion loss of only 2.8 dB. Compared with the typical method of using two temperature-stabilized equal-length fibers that incurs an insertion loss of 20 dB per fiber, the DCM approach achieves high spectral resolution in a much shorter measurement time. Because the dispersion amount and center wavelengths of DCMs can be easily customized, spectral characterization in a wide range of quantum photonic applications should benefit significantly from this technique.

Estimating chlorophyll with thermal and broadband multispectral high resolution imagery from an unmanned aerial system using relevance vector machines for precision agriculture

NASA Astrophysics Data System (ADS)

Elarab, Manal; Ticlavilca, Andres M.; Torres-Rua, Alfonso F.; Maslova, Inga; McKee, Mac

2015-12-01

Precision agriculture requires high-resolution information to enable greater precision in the management of inputs to production. Actionable information about crop and field status must be acquired at high spatial resolution and at a temporal frequency appropriate for timely responses. In this study, high spatial resolution imagery was obtained through the use of a small, unmanned aerial system called AggieAirTM. Simultaneously with the AggieAir flights, intensive ground sampling for plant chlorophyll was conducted at precisely determined locations. This study reports the application of a relevance vector machine coupled with cross validation and backward elimination to a dataset composed of reflectance from high-resolution multi-spectral imagery (VIS-NIR), thermal infrared imagery, and vegetative indices, in conjunction with in situ SPAD measurements from which chlorophyll concentrations were derived, to estimate chlorophyll concentration from remotely sensed data at 15-cm resolution. The results indicate that a relevance vector machine with a thin plate spline kernel type and kernel width of 5.4, having LAI, NDVI, thermal and red bands as the selected set of inputs, can be used to spatially estimate chlorophyll concentration with a root-mean-squared-error of 5.31 μg cm-2, efficiency of 0.76, and 9 relevance vectors.

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.

Retrieving high-resolution surface solar radiation with cloud parameters derived by combining MODIS and MTSAT data

NASA Astrophysics Data System (ADS)

Tang, Wenjun; Qin, Jun; Yang, Kun; Liu, Shaomin; Lu, Ning; Niu, Xiaolei

2016-03-01

Cloud parameters (cloud mask, effective particle radius, and liquid/ice water path) are the important inputs in estimating surface solar radiation (SSR). These parameters can be derived from MODIS with high accuracy, but their temporal resolution is too low to obtain high-temporal-resolution SSR retrievals. In order to obtain hourly cloud parameters, an artificial neural network (ANN) is applied in this study to directly construct a functional relationship between MODIS cloud products and Multifunctional Transport Satellite (MTSAT) geostationary satellite signals. In addition, an efficient parameterization model for SSR retrieval is introduced and, when driven with MODIS atmospheric and land products, its root mean square error (RMSE) is about 100 W m-2 for 44 Baseline Surface Radiation Network (BSRN) stations. Once the estimated cloud parameters and other information (such as aerosol, precipitable water, ozone) are input to the model, we can derive SSR at high spatiotemporal resolution. The retrieved SSR is first evaluated against hourly radiation data at three experimental stations in the Haihe River basin of China. The mean bias error (MBE) and RMSE in hourly SSR estimate are 12.0 W m-2 (or 3.5 %) and 98.5 W m-2 (or 28.9 %), respectively. The retrieved SSR is also evaluated against daily radiation data at 90 China Meteorological Administration (CMA) stations. The MBEs are 9.8 W m-2 (or 5.4 %); the RMSEs in daily and monthly mean SSR estimates are 34.2 W m-2 (or 19.1 %) and 22.1 W m-2 (or 12.3 %), respectively. The accuracy is comparable to or even higher than two other radiation products (GLASS and ISCCP-FD), and the present method is more computationally efficient and can produce hourly SSR data at a spatial resolution of 5 km.

Retrieving high-resolution surface solar radiation with cloud parameters derived by combining MODIS and MTSAT data

NASA Astrophysics Data System (ADS)

Tang, W.; Qin, J.; Yang, K.; Liu, S.; Lu, N.; Niu, X.

2015-12-01

Cloud parameters (cloud mask, effective particle radius and liquid/ice water path) are the important inputs in determining surface solar radiation (SSR). These parameters can be derived from MODIS with high accuracy but their temporal resolution is too low to obtain high temporal resolution SSR retrievals. In order to obtain hourly cloud parameters, the Artificial Neural Network (ANN) is applied in this study to directly construct a functional relationship between MODIS cloud products and Multi-functional Transport Satellite (MTSAT) geostationary satellite signals. Meanwhile, an efficient parameterization model for SSR retrieval is introduced and, when driven with MODIS atmospheric and land products, its root mean square error (RMSE) is about 100 W m-2 for 44 Baseline Surface Radiation Network (BSRN) stations. Once the estimated cloud parameters and other information (such as aerosol, precipitable water, ozone and so on) are input to the model, we can derive SSR at high spatio-temporal resolution. The retrieved SSR is first evaluated against hourly radiation data at three experimental stations in the Haihe River Basin of China. The mean bias error (MBE) and RMSE in hourly SSR estimate are 12.0 W m-2 (or 3.5 %) and 98.5 W m-2 (or 28.9 %), respectively. The retrieved SSR is also evaluated against daily radiation data at 90 China Meteorological Administration (CMA) stations. The MBEs are 9.8 W m-2 (5.4 %); the RMSEs in daily and monthly-mean SSR estimates are 34.2 W m-2 (19.1 %) and 22.1 W m-2 (12.3 %), respectively. The accuracy is comparable or even higher than other two radiation products (GLASS and ISCCP-FD), and the present method is more computationally efficient and can produce hourly SSR data at a spatial resolution of 5 km.

An efficient photogrammetric stereo matching method for high-resolution images

NASA Astrophysics Data System (ADS)

Li, Yingsong; Zheng, Shunyi; Wang, Xiaonan; Ma, Hao

2016-12-01

Stereo matching of high-resolution images is a great challenge in photogrammetry. The main difficulty is the enormous processing workload that involves substantial computing time and memory consumption. In recent years, the semi-global matching (SGM) method has been a promising approach for solving stereo problems in different data sets. However, the time complexity and memory demand of SGM are proportional to the scale of the images involved, which leads to very high consumption when dealing with large images. To solve it, this paper presents an efficient hierarchical matching strategy based on the SGM algorithm using single instruction multiple data instructions and structured parallelism in the central processing unit. The proposed method can significantly reduce the computational time and memory required for large scale stereo matching. The three-dimensional (3D) surface is reconstructed by triangulating and fusing redundant reconstruction information from multi-view matching results. Finally, three high-resolution aerial date sets are used to evaluate our improvement. Furthermore, precise airborne laser scanner data of one data set is used to measure the accuracy of our reconstruction. Experimental results demonstrate that our method remarkably outperforms in terms of time and memory savings while maintaining the density and precision of the 3D cloud points derived.

A high-resolution peak fractionation approach for streamlined screening of nuclear-factor-E2-related factor-2 activators in Salvia miltiorrhiza.

PubMed

Zhang, Hui; Luo, Li-Ping; Song, Hui-Peng; Hao, Hai-Ping; Zhou, Ping; Qi, Lian-Wen; Li, Ping; Chen, Jun

2014-01-24

Generation of a high-purity fraction library for efficiently screening active compounds from natural products is challenging because of their chemical diversity and complex matrices. In this work, a strategy combining high-resolution peak fractionation (HRPF) with a cell-based assay was proposed for target screening of bioactive constituents from natural products. In this approach, peak fractionation was conducted under chromatographic conditions optimized for high-resolution separation of the natural product extract. The HRPF approach was automatically performed according to the predefinition of certain peaks based on their retention times from a reference chromatographic profile. The corresponding HRPF database was collected with a parallel mass spectrometer to ensure purity and characterize the structures of compounds in the various fractions. Using this approach, a set of 75 peak fractions on the microgram scale was generated from 4mg of the extract of Salvia miltiorrhiza. After screening by an ARE-luciferase reporter gene assay, 20 diterpene quinones were selected and identified, and 16 of these compounds were reported to possess novel Nrf2 activation activity. Compared with conventional fixed-time interval fractionation, the HRPF approach could significantly improve the efficiency of bioactive compound discovery and facilitate the uncovering of minor active components. Copyright © 2013 Elsevier B.V. All rights reserved.

Numerical viscosity and resolution of high-order weighted essentially nonoscillatory schemes for compressible flows with high Reynolds numbers.

PubMed

Zhang, Yong-Tao; Shi, Jing; Shu, Chi-Wang; Zhou, Ye

2003-10-01

A quantitative study is carried out in this paper to investigate the size of numerical viscosities and the resolution power of high-order weighted essentially nonoscillatory (WENO) schemes for solving one- and two-dimensional Navier-Stokes equations for compressible gas dynamics with high Reynolds numbers. A one-dimensional shock tube problem, a one-dimensional example with parameters motivated by supernova and laser experiments, and a two-dimensional Rayleigh-Taylor instability problem are used as numerical test problems. For the two-dimensional Rayleigh-Taylor instability problem, or similar problems with small-scale structures, the details of the small structures are determined by the physical viscosity (therefore, the Reynolds number) in the Navier-Stokes equations. Thus, to obtain faithful resolution to these small-scale structures, the numerical viscosity inherent in the scheme must be small enough so that the physical viscosity dominates. A careful mesh refinement study is performed to capture the threshold mesh for full resolution, for specific Reynolds numbers, when WENO schemes of different orders of accuracy are used. It is demonstrated that high-order WENO schemes are more CPU time efficient to reach the same resolution, both for the one-dimensional and two-dimensional test problems.

Semi-automatic mapping of linear-trending bedforms using 'Self-Organizing Maps' algorithm

NASA Astrophysics Data System (ADS)

Foroutan, M.; Zimbelman, J. R.

2017-09-01

Increased application of high resolution spatial data such as high resolution satellite or Unmanned Aerial Vehicle (UAV) images from Earth, as well as High Resolution Imaging Science Experiment (HiRISE) images from Mars, makes it necessary to increase automation techniques capable of extracting detailed geomorphologic elements from such large data sets. Model validation by repeated images in environmental management studies such as climate-related changes as well as increasing access to high-resolution satellite images underline the demand for detailed automatic image-processing techniques in remote sensing. This study presents a methodology based on an unsupervised Artificial Neural Network (ANN) algorithm, known as Self Organizing Maps (SOM), to achieve the semi-automatic extraction of linear features with small footprints on satellite images. SOM is based on competitive learning and is efficient for handling huge data sets. We applied the SOM algorithm to high resolution satellite images of Earth and Mars (Quickbird, Worldview and HiRISE) in order to facilitate and speed up image analysis along with the improvement of the accuracy of results. About 98% overall accuracy and 0.001 quantization error in the recognition of small linear-trending bedforms demonstrate a promising framework.

Ultra high spatial and temporal resolution breast imaging at 7T.

PubMed

van de Bank, B L; Voogt, I J; Italiaander, M; Stehouwer, B L; Boer, V O; Luijten, P R; Klomp, D W J

2013-04-01

There is a need to obtain higher specificity in the detection of breast lesions using MRI. To address this need, Dynamic Contrast-Enhanced (DCE) MRI has been combined with other structural and functional MRI techniques. Unfortunately, owing to time constraints structural images at ultra-high spatial resolution can generally not be obtained during contrast uptake, whereas the relatively low spatial resolution of functional imaging (e.g. diffusion and perfusion) limits the detection of small lesions. To be able to increase spatial as well as temporal resolution simultaneously, the sensitivity of MR detection needs to increase as well as the ability to effectively accelerate the acquisition. The required gain in signal-to-noise ratio (SNR) can be obtained at 7T, whereas acceleration can be obtained with high-density receiver coil arrays. In this case, morphological imaging can be merged with DCE-MRI, and other functional techniques can be obtained at higher spatial resolution, and with less distortion [e.g. Diffusion Weighted Imaging (DWI)]. To test the feasibility of this concept, we developed a unilateral breast coil for 7T. It comprises a volume optimized dual-channel transmit coil combined with a 30-channel receive array coil. The high density of small coil elements enabled efficient acceleration in any direction to acquire ultra high spatial resolution MRI of close to 0.6 mm isotropic detail within a temporal resolution of 69 s, high spatial resolution MRI of 1.5 mm isotropic within an ultra high temporal resolution of 6.7 s and low distortion DWI at 7T, all validated in phantoms, healthy volunteers and a patient with a lesion in the right breast classified as Breast Imaging Reporting and Data System (BI-RADS) IV. Copyright © 2012 John Wiley & Sons, Ltd.

Grayscale transparent metasurface holograms

DOE PAGES

Wang, Lei; Kruk, Sergey; Tang, Hanzhi; ...

2016-12-16

In this paper, we demonstrate transparent metaholograms based on silicon metasurfaces that allow high-resolution grayscale images to be encoded. Finally, the holograms feature the highest diffraction and transmission efficiencies, and operate over a broad spectral range.

Automatic Mrf-Based Registration of High Resolution Satellite Video Data

NASA Astrophysics Data System (ADS)

Platias, C.; Vakalopoulou, M.; Karantzalos, K.

2016-06-01

In this paper we propose a deformable registration framework for high resolution satellite video data able to automatically and accurately co-register satellite video frames and/or register them to a reference map/image. The proposed approach performs non-rigid registration, formulates a Markov Random Fields (MRF) model, while efficient linear programming is employed for reaching the lowest potential of the cost function. The developed approach has been applied and validated on satellite video sequences from Skybox Imaging and compared with a rigid, descriptor-based registration method. Regarding the computational performance, both the MRF-based and the descriptor-based methods were quite efficient, with the first one converging in some minutes and the second in some seconds. Regarding the registration accuracy the proposed MRF-based method significantly outperformed the descriptor-based one in all the performing experiments.

High efficiency microcolumnar Lu2O3:Eu scintillator thin film for hard X-ray microtomography

NASA Astrophysics Data System (ADS)

Marton, Z.; Bhandari, H. B.; Brecher, C.; Miller, S. R.; Singh, B.; Nagarkar, V. V.

2013-03-01

We have developed microstructured Lu2O3:Eu scintillator films capable of providing spatial resolution on the order of micrometers for hard X-ray imaging. In addition to their extraordinary resolution, Lu2O3:Eu films simultaneously provide high absorption efficiency for 20 to 100 keV X-rays, and bright 610 nm emission, with intensity rivalling that of the brightest known scintillators. At present, high spatial resolution of such a magnitude is achieved using ultra-thin scintillators measuring only about 1 to 5 μm in thickness, which limits absorption efficiency to ~3% for 12 keV X-rays and less than 0.1% for 20 to 100 keV X-rays, resulting in excessive measurement time and exposure to the specimen. Lu2O3:Eu would significantly improve that (99.9% @12 keV and 30% @ 70 keV). Important properties and features of our Lu2O3:Eu scintillator material, fabricated by our electron-beam physical vapour deposition (EB-PVD) process, combines superior density of 9.5 g/cm3, microcolumnar structure emitting 48000 photons/MeV whose wavelength is an ideal match for the underlying CCD detector array. We grew thin films measuring 5-50μm in thickness as well as covering areas up to 5 × 5 cm2 which can be a suitable basis for microtomography, digital radiography as well as CT and hard X-ray Micro-Tomography (XMT).

High-resolution X-ray emission spectroscopy with transition-edge sensors: present performance and future potential

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

Uhlig, J.; Doriese, W. B.; Fowler, J. W.

2015-04-21

X-ray emission spectroscopy (XES) is a powerful element-selective tool to analyze the oxidation states of atoms in complex compounds, determine their electronic configuration, and identify unknown compounds in challenging environments. Until now the low efficiency of wavelength-dispersive X-ray spectrometer technology has limited the use of XES, especially in combination with weaker laboratory X-ray sources. More efficient energy-dispersive detectors have either insufficient energy resolution because of the statistical limits described by Fano or too low counting rates to be of practical use. This paper updates an approach to high-resolution X-ray emission spectroscopy that uses a microcalorimeter detector array of superconducting transition-edgemore » sensors (TESs). TES arrays are discussed and compared with conventional methods, and shown under which circumstances they are superior. It is also shown that a TES array can be integrated into a table-top time-resolved X-ray source and a soft X-ray synchrotron beamline to perform emission spectroscopy with good chemical sensitivity over a very wide range of energies.« less

Efficient creation of electron vortex beams for high resolution STEM imaging.

PubMed

Béché, A; Juchtmans, R; Verbeeck, J

2017-07-01

The recent discovery of electron vortex beams carrying quantised angular momentum in the TEM has led to an active field of research, exploring a variety of potential applications including the possibility of mapping magnetic states at the atomic scale. A prerequisite for this is the availability of atomic sized electron vortex beams at high beam current and mode purity. In this paper we present recent progress showing that by making use of the Aharonov-Bohm effect near the tip of a long single domain ferromagnetic Nickel needle, a very efficient aperture for the production of electron vortex beams can be realised. The aperture transmits more than 99% of all electrons and provides a vortex mode purity of up to 92%. Placing this aperture in the condenser plane of a state of the art Cs corrected microscope allows us to demonstrate atomic resolution HAADF STEM images with spatial resolution better than 1 Angström, in agreement with theoretical expectations and only slightly inferior to the performance of a non-vortex probe on the same instrument. Copyright © 2016 Elsevier B.V. All rights reserved.

High-resolution neutron diffraction study of microstructural changes in nanocrystalline ball-milled niobium carbide NbC{sub 0.93}

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

Balagurov, Anatoly M.; Bobrikov, Ivan A.; Bokuchava, Gizo D.

2015-11-15

High resolution neutron diffraction was applied for elucidating of the microstructural evolution of nanocrystalline niobium carbide NbC{sub 0.93} powders subjected to high-energy ball milling. The diffraction patterns were collected with the high resolution Fourier diffractometer HRFD by using the reverse time-of-flight (RTOF) mode of data acquisition. The traditional single diffraction line analysis, the Rietveld method and more advanced Whole Powder Pattern Modeling technique were applied for the data analysis. The comparison of these techniques was performed. It is established that short-time milling produces a non-uniform powder, in which two distinct fractions with differing microstructure can be identified. Part of themore » material is in fact milled efficiently, with a reduction in grain size, an increase in the quantity of defects, and a corresponding tendency to decarburize reaching a composition NbC{sub 0.80} after 15 h of milling. The rest of the powder is less efficiently processed and preserves its composition and lower defect content. Larger milling times should have homogenized the system by increasing the efficiently milled fraction, but the material is unable to reach a uniform and homogeneous state. It is definitely shown that RTOF neutron diffraction patterns can provide the very accurate data for microstructure analysis of nanocrystalline powders. - Highlights: • The NbC{sub 0.93} powder was processed by high-energy ball milling. • The microstrain and dislocation density increase with milling time increase. • The corresponding decrease in crystallite size with milling time was observed. • The material exhibits the presence of two fractions after ball milling. • The RTOF neutron diffraction data are suitable for accurate microstructure analysis.« less

Selecting Resolving Agents with Respect to Their Eutectic Compositions.

PubMed

Szeleczky, Zsolt; Semsey, Sándor; Bagi, Péter; Pálovics, Emese; Faigl, Ferenc; Fogassy, Elemér

2016-03-01

In order to develop a resolution procedure for a given racemic compound, the first and the most important step is finding the most suitable resolving agent. We studied 18 individual resolutions that were carried out with resolving agents having high eutectic composition. We found that very high enantiomeric excess values were obtained in all cases. We assume that the eutectic composition of a given resolving agent is one of the most important properties that should always be considered during the search for the most efficient resolving agent. © 2016 Wiley Periodicals, Inc.

3D high- and super-resolution imaging using single-objective SPIM.

PubMed

Galland, Remi; Grenci, Gianluca; Aravind, Ajay; Viasnoff, Virgile; Studer, Vincent; Sibarita, Jean-Baptiste

2015-07-01

Single-objective selective-plane illumination microscopy (soSPIM) is achieved with micromirrored cavities combined with a laser beam-steering unit installed on a standard inverted microscope. The illumination and detection are done through the same objective. soSPIM can be used with standard sample preparations and features high background rejection and efficient photon collection, allowing for 3D single-molecule-based super-resolution imaging of whole cells or cell aggregates. Using larger mirrors enabled us to broaden the capabilities of our system to image Drosophila embryos.

High-Efficiency High-Resolution Global Model Developments at the NASA Goddard Data Assimilation Office

NASA Technical Reports Server (NTRS)

Lin, Shian-Jiann; Atlas, Robert (Technical Monitor)

2002-01-01

The Data Assimilation Office (DAO) has been developing a new generation of ultra-high resolution General Circulation Model (GCM) that is suitable for 4-D data assimilation, numerical weather predictions, and climate simulations. These three applications have conflicting requirements. For 4-D data assimilation and weather predictions, it is highly desirable to run the model at the highest possible spatial resolution (e.g., 55 km or finer) so as to be able to resolve and predict socially and economically important weather phenomena such as tropical cyclones, hurricanes, and severe winter storms. For climate change applications, the model simulations need to be carried out for decades, if not centuries. To reduce uncertainty in climate change assessments, the next generation model would also need to be run at a fine enough spatial resolution that can at least marginally simulate the effects of intense tropical cyclones. Scientific problems (e.g., parameterization of subgrid scale moist processes) aside, all three areas of application require the model's computational performance to be dramatically improved as compared to the previous generation. In this talk, I will present the current and future developments of the "finite-volume dynamical core" at the Data Assimilation Office. This dynamical core applies modem monotonicity preserving algorithms and is genuinely conservative by construction, not by an ad hoc fixer. The "discretization" of the conservation laws is purely local, which is clearly advantageous for resolving sharp gradient flow features. In addition, the local nature of the finite-volume discretization also has a significant advantage on distributed memory parallel computers. Together with a unique vertically Lagrangian control volume discretization that essentially reduces the dimension of the computational problem from three to two, the finite-volume dynamical core is very efficient, particularly at high resolutions. I will also present the computational design of the dynamical core using a hybrid distributed-shared memory programming paradigm that is portable to virtually any of today's high-end parallel super-computing clusters.

High-Efficiency High-Resolution Global Model Developments at the NASA Goddard Data Assimilation Office

NASA Technical Reports Server (NTRS)

Lin, Shian-Jiann; Atlas, Robert (Technical Monitor)

2002-01-01

The Data Assimilation Office (DAO) has been developing a new generation of ultra-high resolution General Circulation Model (GCM) that is suitable for 4-D data assimilation, numerical weather predictions, and climate simulations. These three applications have conflicting requirements. For 4-D data assimilation and weather predictions, it is highly desirable to run the model at the highest possible spatial resolution (e.g., 55 kin or finer) so as to be able to resolve and predict socially and economically important weather phenomena such as tropical cyclones, hurricanes, and severe winter storms. For climate change applications, the model simulations need to be carried out for decades, if not centuries. To reduce uncertainty in climate change assessments, the next generation model would also need to be run at a fine enough spatial resolution that can at least marginally simulate the effects of intense tropical cyclones. Scientific problems (e.g., parameterization of subgrid scale moist processes) aside, all three areas of application require the model's computational performance to be dramatically improved as compared to the previous generation. In this talk, I will present the current and future developments of the "finite-volume dynamical core" at the Data Assimilation Office. This dynamical core applies modem monotonicity preserving algorithms and is genuinely conservative by construction, not by an ad hoc fixer. The "discretization" of the conservation laws is purely local, which is clearly advantageous for resolving sharp gradient flow features. In addition, the local nature of the finite-volume discretization also has a significant advantage on distributed memory parallel computers. Together with a unique vertically Lagrangian control volume discretization that essentially reduces the dimension of the computational problem from three to two, the finite-volume dynamical core is very efficient, particularly at high resolutions. I will also present the computational design of the dynamical core using a hybrid distributed- shared memory programming paradigm that is portable to virtually any of today's high-end parallel super-computing clusters.

A method of extending the depth of focus of the high-resolution X-ray imaging system employing optical lens and scintillator: a phantom study.

PubMed

Li, Guang; Luo, Shouhua; Yan, Yuling; Gu, Ning

2015-01-01

The high-resolution X-ray imaging system employing synchrotron radiation source, thin scintillator, optical lens and advanced CCD camera can achieve a resolution in the range of tens of nanometers to sub-micrometer. Based on this advantage, it can effectively image tissues, cells and many other small samples, especially the calcification in the vascular or in the glomerulus. In general, the thickness of the scintillator should be several micrometers or even within nanometers because it has a big relationship with the resolution. However, it is difficult to make the scintillator so thin, and additionally thin scintillator may greatly reduce the efficiency of collecting photons. In this paper, we propose an approach to extend the depth of focus (DOF) to solve these problems. We develop equation sets by deducing the relationship between the high-resolution image generated by the scintillator and the degraded blur image due to defect of focus first, and then we adopt projection onto convex sets (POCS) and total variation algorithm to get the solution of the equation sets and to recover the blur image. By using a 20 μm thick unmatching scintillator to replace the 1 μm thick matching one, we simulated a high-resolution X-ray imaging system and got a degraded blur image. Based on the algorithm proposed, we recovered the blur image and the result in the experiment showed that the proposed algorithm has good performance on the recovery of image blur caused by unmatching thickness of scintillator. The method proposed is testified to be able to efficiently recover the degraded image due to defect of focus. But, the quality of the recovery image especially of the low contrast image depends on the noise level of the degraded blur image, so there is room for improving and the corresponding denoising algorithm is worthy for further study and discussion.

A method of extending the depth of focus of the high-resolution X-ray imaging system employing optical lens and scintillator: a phantom study

PubMed Central

2015-01-01

Background The high-resolution X-ray imaging system employing synchrotron radiation source, thin scintillator, optical lens and advanced CCD camera can achieve a resolution in the range of tens of nanometers to sub-micrometer. Based on this advantage, it can effectively image tissues, cells and many other small samples, especially the calcification in the vascular or in the glomerulus. In general, the thickness of the scintillator should be several micrometers or even within nanometers because it has a big relationship with the resolution. However, it is difficult to make the scintillator so thin, and additionally thin scintillator may greatly reduce the efficiency of collecting photons. Methods In this paper, we propose an approach to extend the depth of focus (DOF) to solve these problems. We develop equation sets by deducing the relationship between the high-resolution image generated by the scintillator and the degraded blur image due to defect of focus first, and then we adopt projection onto convex sets (POCS) and total variation algorithm to get the solution of the equation sets and to recover the blur image. Results By using a 20 μm thick unmatching scintillator to replace the 1 μm thick matching one, we simulated a high-resolution X-ray imaging system and got a degraded blur image. Based on the algorithm proposed, we recovered the blur image and the result in the experiment showed that the proposed algorithm has good performance on the recovery of image blur caused by unmatching thickness of scintillator. Conclusions The method proposed is testified to be able to efficiently recover the degraded image due to defect of focus. But, the quality of the recovery image especially of the low contrast image depends on the noise level of the degraded blur image, so there is room for improving and the corresponding denoising algorithm is worthy for further study and discussion. PMID:25602532

Adaptive optics high-resolution IR spectroscopy with silicon grisms and immersion gratings

NASA Astrophysics Data System (ADS)

Ge, Jian; McDavitt, Daniel L.; Chakraborty, Abhijit; Bernecker, John L.; Miller, Shane

2003-02-01

The breakthrough of silicon immersion grating technology at Penn State has the ability to revolutionize high-resolution infrared spectroscopy when it is coupled with adaptive optics at large ground-based telescopes. Fabrication of high quality silicon grism and immersion gratings up to 2 inches in dimension, less than 1% integrated scattered light, and diffraction-limited performance becomes a routine process thanks to newly developed techniques. Silicon immersion gratings with etched dimensions of ~ 4 inches are being developed at Penn State. These immersion gratings will be able to provide a diffraction-limited spectral resolution of R = 300,000 at 2.2 micron, or 130,000 at 4.6 micron. Prototype silicon grisms have been successfully used in initial scientific observations at the Lick 3m telescope with adaptive optics. Complete K band spectra of a total of 6 T Tauri and Ae/Be stars and their close companions at a spectral resolution of R ~ 3000 were obtained. This resolving power was achieved by using a silicon echelle grism with a 5 mm pupil diameter in an IR camera. These results represent the first scientific observations conducted by the high-resolution silicon grisms, and demonstrate the extremely high dispersing power of silicon-based gratings. New discoveries from this high spatial and spectral resolution IR spectroscopy will be reported. The future of silicon-based grating applications in ground-based AO IR instruments is promising. Silicon immersion gratings will make very high-resolution spectroscopy (R > 100,000) feasible with compact instruments for implementation on large telescopes. Silicon grisms will offer an efficient way to implement low-cost medium to high resolution IR spectroscopy (R ~ 1000-50000) through the conversion of existing cameras into spectrometers by locating a grism in the instrument's pupil location.

Efficient Data Mining for Local Binary Pattern in Texture Image Analysis

PubMed Central

Kwak, Jin Tae; Xu, Sheng; Wood, Bradford J.

2015-01-01

Local binary pattern (LBP) is a simple gray scale descriptor to characterize the local distribution of the grey levels in an image. Multi-resolution LBP and/or combinations of the LBPs have shown to be effective in texture image analysis. However, it is unclear what resolutions or combinations to choose for texture analysis. Examining all the possible cases is impractical and intractable due to the exponential growth in a feature space. This limits the accuracy and time- and space-efficiency of LBP. Here, we propose a data mining approach for LBP, which efficiently explores a high-dimensional feature space and finds a relatively smaller number of discriminative features. The features can be any combinations of LBPs. These may not be achievable with conventional approaches. Hence, our approach not only fully utilizes the capability of LBP but also maintains the low computational complexity. We incorporated three different descriptors (LBP, local contrast measure, and local directional derivative measure) with three spatial resolutions and evaluated our approach using two comprehensive texture databases. The results demonstrated the effectiveness and robustness of our approach to different experimental designs and texture images. PMID:25767332

Single Anisotropic 3-D MR Image Upsampling via Overcomplete Dictionary Trained From In-Plane High Resolution Slices.

PubMed

Jia, Yuanyuan; He, Zhongshi; Gholipour, Ali; Warfield, Simon K

2016-11-01

In magnetic resonance (MR), hardware limitation, scanning time, and patient comfort often result in the acquisition of anisotropic 3-D MR images. Enhancing image resolution is desired but has been very challenging in medical image processing. Super resolution reconstruction based on sparse representation and overcomplete dictionary has been lately employed to address this problem; however, these methods require extra training sets, which may not be always available. This paper proposes a novel single anisotropic 3-D MR image upsampling method via sparse representation and overcomplete dictionary that is trained from in-plane high resolution slices to upsample in the out-of-plane dimensions. The proposed method, therefore, does not require extra training sets. Abundant experiments, conducted on simulated and clinical brain MR images, show that the proposed method is more accurate than classical interpolation. When compared to a recent upsampling method based on the nonlocal means approach, the proposed method did not show improved results at low upsampling factors with simulated images, but generated comparable results with much better computational efficiency in clinical cases. Therefore, the proposed approach can be efficiently implemented and routinely used to upsample MR images in the out-of-planes views for radiologic assessment and postacquisition processing.

Fast and high resolution thermal detector based on an aluminum nitride piezoelectric microelectromechanical resonator with an integrated suspended heat absorbing element

NASA Astrophysics Data System (ADS)

Hui, Yu; Rinaldi, Matteo

2013-03-01

This letter presents a miniaturized, fast, and high resolution thermal detector, in which a heat absorbing element and a temperature sensitive microelectromechanical system (MEMS) resonator are perfectly overlapped but separated by a microscale air gap. This unique design guarantees efficient and fast (˜10s μs) heat transfer from the absorbing element to the temperature sensitive device and enables high resolution thermal power detection (˜nW), thanks to the low noise performance of the high quality factor (Q = 2305) MEMS resonant thermal detector. A device prototype was fabricated, and its detection capabilities were experimentally characterized. A thermal power as low as 150 nW was experimentally measured, and a noise equivalent power of 6.5 nW/Hz1/2 was extracted. A device thermal time constant of only 350 μs was measured (smallest ever reported for MEMS resonant thermal detectors), indicating the great potential of the proposed technology for the implementation of ultra-fast and high resolution un-cooled resonant thermal detectors.

A high-resolution programmable Vernier delay generator based on carry chains in FPGA

NASA Astrophysics Data System (ADS)

Cui, Ke; Li, Xiangyu; Zhu, Rihong

2017-06-01

This paper presents an architecture of a high-resolution delay generator implemented in a single field programmable gate array chip by exploiting the method of utilizing dedicated carry chains. It serves as the core component in various physical instruments. The proposed delay generator contains the coarse delay step and the fine delay step to guarantee both large dynamic range and high resolution. The carry chains are organized in the Vernier delay loop style to fulfill the fine delay step with high precision and high linearity. The delay generator was implemented in the EP3SE110F1152I3 Stratix III device from Altera on a self-designed test board. Test results show that the obtained resolution is 38.6 ps, and the differential nonlinearity/integral nonlinearity is in the range of [-0.18 least significant bit (LSB), 0.24 LSB]/(-0.02 LSB, 0.01 LSB) under the nominal supply voltage of 1100 mV and environmental temperature of 2 0°C. The delay generator is rather efficient concerning resource cost, which uses only 668 look-up tables and 146 registers in total.

Analysis of X-ray Spectra of High-Z Elements obtained on Nike with high spectral and spatial resolution

NASA Astrophysics Data System (ADS)

Aglitskiy, Yefim; Weaver, J. L.; Karasik, M.; Serlin, V.; Obenschain, S. P.; Ralchenko, Yu.

2014-10-01

The spectra of multi-charged ions of Hf, Ta, W, Pt, Au and Bi have been studied on Nike krypton-fluoride laser facility with the help of two kinds of X-ray spectrometers. First, survey instrument covering a spectral range from 0.5 to 19.5 angstroms which allows simultaneous observation of both M- and N- spectra of above mentioned elements with high spectral resolution. Second, an imaging spectrometer with interchangeable spherically bent Quartz crystals that added higher efficiency, higher spectral resolution and high spatial resolution to the qualities of the former one. Multiple spectral lines with X-ray energies as high as 4 keV that belong to the isoelectronic sequences of Fe, Co, Ni, Cu and Zn were identified with the help of NOMAD package developed by Dr. Yu. Ralchenko and colleagues. In our continuous effort to support DOE-NNSA's inertial fusion program, this campaign covered a wide range of plasma conditions that result in production of relatively energetic X-rays. Work supported by the US DOE/NNSA.

Four dimensional lidar imaging of the atmosphere (Invited)

NASA Astrophysics Data System (ADS)

Eloranta, E.

2010-12-01

High resolution four-dimensional depictions of atmospheric structure are needed for many atmospheric investigations. Scanning lidar offers the potential to provide high spatial and temporal resolution four-dimensional imaging of atmospheric structure. This paper will use data acquired with the University of Wisconsin Volume Imaging Lidar (VIL) to illustrate the potential of such measurements, describe the necessary lidar performance requirements , and provide measurement examples. The University of Wisconsin Volume imaging lidar acquired it's first data in the 1987 FIFE experiment and was operated in several deployments until it was mothballed after the 1997-98 Lake-ICE experiment. Although this data is old and the system is now obsolete, the data illustrates the power of the measurement approach and the system characteristics needed to acquire such data. The key challenge in acquiring useful 4-D scan is to provide high spatial resolution along with a scan repeat time short enough to maintain temporal coherence between successive images. This requires a high power transmitter, high pulse repetition rates, large optics, high quantum efficiency, good optical throughput and fast data acquisition. The VIL operated at a wavelength of 1064 nm, emitting an average power of 40 W at a repetition rate of 100 Hz. The receiver utilized 0.5 m diameter telescope with an avalanche photodiode detector that provides a quantum efficiency of ~35%. Operating at the fundamental Nd:YAG wavelength of 1064 rather than the more usual doubled 532 nm wavelength, avoided the loss of power and photon numbers involved in frequency doubling. It also allowed use of the high quantum efficiency of the avalanche photodiode in place of the the lower efficiency photomultiplier. Signal-to-noise calculations show that the combination of higher photon numbers and greater quantum efficiency more than maked up for the large dark current noise of the APD-amplifier combination. The high power and sensitivity of the VIL yielded unique measurements, however the high power and 1064 nm wavelength combine to create an eye safety hazard that severely restricted conditions under which it could be deployed. It is now becoming possible to operate at eye safe wavelengths to mitigate this problem, although the sensitivity of these systems do not yet match that of the VIL. Several examples of VIL data will be presented, including: 1) placing insitu aircraft measurements into context of their position within the temporal and spatial structure of clear convection, 2) mapping the spatial structure of cirrus clouds within multiple pixels of a satellite retrievals, 3) showing high resolution images of a land breeze front, 4) mapping pollutant plumes, 4) mapping two-dimensional wind fields, 5) comparison of LES predicted spatial and temporal statistics of aerosol structure with VIL measurements. Boundary layer convective fields were imaged to a range ~15 km with a 3-d repeat time of a few minutes. Cirrus cloud observations extend to maximum ranges of greater than 60 km.

High-resolution harmonic motion imaging (HR-HMI) for tissue biomechanical property characterization

PubMed Central

Ma, Teng; Qian, Xuejun; Chiu, Chi Tat; Yu, Mingyue; Jung, Hayong; Tung, Yao-Sheng; Shung, K. Kirk

2015-01-01

Background Elastography, capable of mapping the biomechanical properties of biological tissues, serves as a useful technique for clinicians to perform disease diagnosis and determine stages of many diseases. Many acoustic radiation force (ARF) based elastography, including acoustic radiation force impulse (ARFI) imaging and harmonic motion imaging (HMI), have been developed to remotely assess the elastic properties of tissues. However, due to the lower operating frequencies of these approaches, their spatial resolutions are insufficient for revealing stiffness distribution on small scale applications, such as cancerous tumor margin detection, atherosclerotic plaque composition analysis and ophthalmologic tissue characterization. Though recently developed ARF-based optical coherence elastography (OCE) methods open a new window for the high resolution elastography, shallow imaging depths significantly limit their usefulness in clinics. Methods The aim of this study is to develop a high-resolution HMI method to assess the tissue biomechanical properties with acceptable field of view (FOV) using a 4 MHz ring transducer for efficient excitation and a 40 MHz needle transducer for accurate detection. Under precise alignment of two confocal transducers, the high-resolution HMI system has a lateral resolution of 314 µm and an axial resolution of 
147 µm with an effective FOV of 2 mm in depth. Results The performance of this high resolution imaging system was validated on the agar-based tissue mimicking phantoms with different stiffness distributions. These data demonstrated the imaging system’s improved resolution and sensitivity on differentiating materials with varying stiffness. In addition, ex vivo imaging of a human atherosclerosis coronary artery demonstrated the capability of high resolution HMI in identifying layer-specific structures and characterizing atherosclerotic plaques based on their stiffness differences. Conclusions All together high resolution HMI appears to be a promising ultrasound-only technology for characterizing tissue biomechanical properties at the microstructural level to improve the image-based diseases diagnosis in multiple clinical applications. PMID:25694960

High-resolution harmonic motion imaging (HR-HMI) for tissue biomechanical property characterization.

PubMed

Ma, Teng; Qian, Xuejun; Chiu, Chi Tat; Yu, Mingyue; Jung, Hayong; Tung, Yao-Sheng; Shung, K Kirk; Zhou, Qifa

2015-02-01

Elastography, capable of mapping the biomechanical properties of biological tissues, serves as a useful technique for clinicians to perform disease diagnosis and determine stages of many diseases. Many acoustic radiation force (ARF) based elastography, including acoustic radiation force impulse (ARFI) imaging and harmonic motion imaging (HMI), have been developed to remotely assess the elastic properties of tissues. However, due to the lower operating frequencies of these approaches, their spatial resolutions are insufficient for revealing stiffness distribution on small scale applications, such as cancerous tumor margin detection, atherosclerotic plaque composition analysis and ophthalmologic tissue characterization. Though recently developed ARF-based optical coherence elastography (OCE) methods open a new window for the high resolution elastography, shallow imaging depths significantly limit their usefulness in clinics. The aim of this study is to develop a high-resolution HMI method to assess the tissue biomechanical properties with acceptable field of view (FOV) using a 4 MHz ring transducer for efficient excitation and a 40 MHz needle transducer for accurate detection. Under precise alignment of two confocal transducers, the high-resolution HMI system has a lateral resolution of 314 µm and an axial resolution of 
147 µm with an effective FOV of 2 mm in depth. The performance of this high resolution imaging system was validated on the agar-based tissue mimicking phantoms with different stiffness distributions. These data demonstrated the imaging system's improved resolution and sensitivity on differentiating materials with varying stiffness. In addition, ex vivo imaging of a human atherosclerosis coronary artery demonstrated the capability of high resolution HMI in identifying layer-specific structures and characterizing atherosclerotic plaques based on their stiffness differences. All together high resolution HMI appears to be a promising ultrasound-only technology for characterizing tissue biomechanical properties at the microstructural level to improve the image-based diseases diagnosis in multiple clinical applications.

Detector motion method to increase spatial resolution in photon-counting detectors

NASA Astrophysics Data System (ADS)

Lee, Daehee; Park, Kyeongjin; Lim, Kyung Taek; Cho, Gyuseong

2017-03-01

Medical imaging requires high spatial resolution of an image to identify fine lesions. Photon-counting detectors in medical imaging have recently been rapidly replacing energy-integrating detectors due to the former`s high spatial resolution, high efficiency and low noise. Spatial resolution in a photon counting image is determined by the pixel size. Therefore, the smaller the pixel size, the higher the spatial resolution that can be obtained in an image. However, detector redesigning is required to reduce pixel size, and an expensive fine process is required to integrate a signal processing unit with reduced pixel size. Furthermore, as the pixel size decreases, charge sharing severely deteriorates spatial resolution. To increase spatial resolution, we propose a detector motion method using a large pixel detector that is less affected by charge sharing. To verify the proposed method, we utilized a UNO-XRI photon-counting detector (1-mm CdTe, Timepix chip) at the maximum X-ray tube voltage of 80 kVp. A similar spatial resolution of a 55- μm-pixel image was achieved by application of the proposed method to a 110- μm-pixel detector with a higher signal-to-noise ratio. The proposed method could be a way to increase spatial resolution without a pixel redesign when pixels severely suffer from charge sharing as pixel size is reduced.

Inverse design of near unity efficiency perfectly vertical grating couplers.

PubMed

Michaels, Andrew; Yablonovitch, Eli

2018-02-19

Efficient coupling between integrated optical waveguides and optical fibers is essential to the success of silicon photonics. While many solutions exist, perfectly vertical grating couplers that scatter light out of a waveguide in the direction normal to the waveguide's top surface are an ideal candidate due to their potential to reduce packaging complexity. Designing such couplers with high efficiencies, however, has proven difficult. In this paper, we use inverse electromagnetic design techniques to optimize a high efficiency two-layer perfectly vertical silicon grating coupler. Our base design achieves a chip-to-fiber coupling efficiency of 99.2% (-0.035 dB) at 1550 nm. Using this base design as a starting point, we run subsequent constrained optimizations to realize vertical couplers with coupling efficiencies over 96% and back reflections of less than -40 dB which can be fabricated using 65 nm-resolution lithography. These results demonstrate a new path forward for designing fabrication-tolerant ultra high efficiency grating couplers.

Payload Configurations for Efficient Image Acquisition - Indian Perspective

NASA Astrophysics Data System (ADS)

Samudraiah, D. R. M.; Saxena, M.; Paul, S.; Narayanababu, P.; Kuriakose, S.; Kiran Kumar, A. S.

2014-11-01

The world is increasingly depending on remotely sensed data. The data is regularly used for monitoring the earth resources and also for solving problems of the world like disasters, climate degradation, etc. Remotely sensed data has changed our perspective of understanding of other planets. With innovative approaches in data utilization, the demands of remote sensing data are ever increasing. More and more research and developments are taken up for data utilization. The satellite resources are scarce and each launch costs heavily. Each launch is also associated with large effort for developing the hardware prior to launch. It is also associated with large number of software elements and mathematical algorithms post-launch. The proliferation of low-earth and geostationary satellites has led to increased scarcity in the available orbital slots for the newer satellites. Indian Space Research Organization has always tried to maximize the utility of satellites. Multiple sensors are flown on each satellite. In each of the satellites, sensors are designed to cater to various spectral bands/frequencies, spatial and temporal resolutions. Bhaskara-1, the first experimental satellite started with 2 bands in electro-optical spectrum and 3 bands in microwave spectrum. The recent Resourcesat-2 incorporates very efficient image acquisition approach with multi-resolution (3 types of spatial resolution) multi-band (4 spectral bands) electro-optical sensors (LISS-4, LISS-3* and AWiFS). The system has been designed to provide data globally with various data reception stations and onboard data storage capabilities. Oceansat-2 satellite has unique sensor combination with 8 band electro-optical high sensitive ocean colour monitor (catering to ocean and land) along with Ku band scatterometer to acquire information on ocean winds. INSAT- 3D launched recently provides high resolution 6 band image data in visible, short-wave, mid-wave and long-wave infrared spectrum. It also has 19 band sounder for providing vertical profile of water vapour, temperature, etc. The same system has data relay transponders for acquiring data from weather stations. The payload configurations have gone through significant changes over the years to increase data rate per kilogram of payload. Future Indian remote sensing systems are planned with very high efficient ways of image acquisition. This paper analyses the strides taken by ISRO (Indian Space research Organisation) in achieving high efficiency in remote sensing image data acquisition. Parameters related to efficiency of image data acquisition are defined and a methodology is worked out to compute the same. Some of the Indian payloads are analysed with respect to some of the system/ subsystem parameters that decide the configuration of payload. Based on the analysis, possible configuration approaches that can provide high efficiency are identified. A case study is carried out with improved configuration and the results of efficiency improvements are reported. This methodology may be used for assessing other electro-optical payloads or missions and can be extended to other types of payloads and missions.

Thermal neutron detector based on COTS CMOS imagers and a conversion layer containing Gadolinium

NASA Astrophysics Data System (ADS)

Pérez, Martín; Blostein, Juan Jerónimo; Bessia, Fabricio Alcalde; Tartaglione, Aureliano; Sidelnik, Iván; Haro, Miguel Sofo; Suárez, Sergio; Gimenez, Melisa Lucía; Berisso, Mariano Gómez; Lipovetzky, Jose

2018-06-01

In this work we will introduce a novel low cost position sensitive thermal neutron detection technique, based on a Commercial Off The Shelf CMOS image sensor covered with a Gadolinium containing conversion layer. The feasibility of the neutron detection technique implemented in this work has been experimentally demonstrated. A thermal neutron detection efficiency of 11.3% has been experimentally obtained with a conversion layer of 11.6 μm. It was experimentally verified that the thermal neutron detection efficiency of this technique is independent on the intensity of the incident thermal neutron flux, which was confirmed for conversion layers of different thicknesses. Based on the experimental results, a spatial resolution better than 25 μm is expected. This spatial resolution makes the proposed technique specially useful for neutron beam characterization, neutron beam dosimetry, high resolution neutron imaging, and several neutron scattering techniques.

Numerical study of low-current steady arcs

NASA Technical Reports Server (NTRS)

Kim, S. C.; Nagamatsu, H. T.

1992-01-01

The development of a high-efficiency CW YLF laser doped with Er,Tm,Ho: and featuring a strongly focusing resonator that collects a high density of pump power on the active crystal is described. The emission is investigated at 2.06 microns and a tuning range both at liquid-nitrogen (77 K) and at dry-ice (210 K) temperature. The noise characteristics and the long-term power stability of the laser is studied with an eye to employing this source for high-resolution spectroscopy in the 2-micron wavelength region. The detection of several absorption lines of NH3 at low pressure is described. The output power of the laser as a function of the power impinging on the crystal for different transmission of the output mirror is illustrated. The best result obtained is 1.46 W output for 3.2 W of argon pump. The minimum threshold achieved is 3.5 mW with a 1-percent transmission mirror. It is concluded that it is possible to develop a highly efficient Ho:YLF laser featuring low noise and sufficient tunability for high-resolution spectroscopy in the 2-micron region.

Advanced microscopy of star-shaped gold nanoparticles and their adsorption-uptake by macrophages

PubMed Central

Plascencia-Villa, Germán; Bahena, Daniel; Rodríguez, Annette R.; Ponce, Arturo; José-Yacamán, Miguel

2013-01-01

Metallic nanoparticles have diverse applications in biomedicine, as diagnostics, image contrast agents, nanosensors and drug delivery systems. Anisotropic metallic nanoparticles possess potential applications in cell imaging and therapy+diagnostics (theranostics), but controlled synthesis and growth of these anisotropic or branched nanostructures has been challenging and usually require use of high concentrations of surfactants. Star-shaped gold nanoparticles were synthesized in high yield through a seed mediated route using HEPES as a precise shape-directing capping agent. Characterization was performed using advanced electron microscopy techniques including atomic resolution TEM, obtaining a detailed characterization of nanostructure and atomic arrangement. Spectroscopy techniques showed that particles have narrow size distribution, monodispersity and high colloidal stability, with absorbance into NIR region and high efficiency for SERS applications. Gold nanostars showed to be biocompatible and efficiently adsorbed and internalized by macrophages, as revealed by advanced FE-SEM and backscattered electron imaging techniques of complete unstained uncoated cells. Additionally, low voltage STEM and X-ray microanalysis revealed the ultra-structural location and confirmed stability of nanoparticles after endocytosis with high spatial resolution. PMID:23443314

Magnetoacoustic microscopic imaging of conductive objects and nanoparticles distribution

NASA Astrophysics Data System (ADS)

Liu, Siyu; Zhang, Ruochong; Luo, Yunqi; Zheng, Yuanjin

2017-09-01

Magnetoacoustic tomography has been demonstrated as a powerful and low-cost multi-wave imaging modality. However, due to limited spatial resolution and detection efficiency of magnetoacoustic signal, full potential of the magnetoacoustic imaging remains to be tapped. Here we report a high-resolution magnetoacoustic microscopy method, where magnetic stimulation is provided by a compact solenoid resonance coil connected with a matching network, and acoustic reception is realized by using a high-frequency focused ultrasound transducer. Scanning the magnetoacoustic microscopy system perpendicularly to the acoustic axis of the focused transducer would generate a two-dimensional microscopic image with acoustically determined lateral resolution. It is analyzed theoretically and demonstrated experimentally that magnetoacoustic generation in this microscopic system depends on the conductivity profile of conductive objects and localized distribution of superparamagnetic iron magnetic nanoparticles, based on two different but related implementations. The lateral resolution is characterized. Directional nature of magnetoacoustic vibration and imaging sensitivity for mapping magnetic nanoparticles are also discussed. The proposed microscopy system offers a high-resolution method that could potentially map intrinsic conductivity distribution in biological tissue and extraneous magnetic nanoparticles.

Digitizing an Analog Radiography Teaching File Under Time Constraint: Trade-Offs in Efficiency and Image Quality.

PubMed

Loehfelm, Thomas W; Prater, Adam B; Debebe, Tequam; Sekhar, Aarti K

2017-02-01

We digitized the radiography teaching file at Black Lion Hospital (Addis Ababa, Ethiopia) during a recent trip, using a standard digital camera and a fluorescent light box. Our goal was to photograph every radiograph in the existing library while optimizing the final image size to the maximum resolution of a high quality tablet computer, preserving the contrast resolution of the radiographs, and minimizing total library file size. A secondary important goal was to minimize the cost and time required to take and process the images. Three workers were able to efficiently remove the radiographs from their storage folders, hang them on the light box, operate the camera, catalog the image, and repack the radiographs back to the storage folder. Zoom, focal length, and film speed were fixed, while aperture and shutter speed were manually adjusted for each image, allowing for efficiency and flexibility in image acquisition. Keeping zoom and focal length fixed, which kept the view box at the same relative position in all of the images acquired during a single photography session, allowed unused space to be batch-cropped, saving considerable time in post-processing, at the expense of final image resolution. We present an analysis of the trade-offs in workflow efficiency and final image quality, and demonstrate that a few people with minimal equipment can efficiently digitize a teaching file library.

A high-resolution, confocal laser-scanning microscope and flash photolysis system for physiological studies.

PubMed

Parker, I; Callamaras, N; Wier, W G

1997-06-01

We describe the construction of a high-resolution confocal laser-scanning microscope, and illustrate its use for studying elementary Ca2+ signalling events in cells. An avalanche photodiode module and simple optical path provide a high efficiency system for detection of fluorescence signals, allowing use of a small confocal aperture giving near diffraction-limited spatial resolution (< 300 nm lateral and < 400 nm axial). When operated in line-scan mode, the maximum temporal resolution is 1 ms, and the associated computer software allows complete flexibility to record line-scans continuously for long (minutes) periods or to obtain any desired pixel resolution in x-y scans. An independent UV irradiation system permits simultaneous photolysis of caged compounds over either a uniform, wide field (arc lamp source) or at a tightly focussed spot (frequency-tripled Nd:YAG laser). The microscope thus provides a versatile tool for optical studies of dynamic cellular processes, as well as excellent resolution for morphological studies. The confocal scanner can be added to virtually any inverted microscope for a component cost that is only a small fraction of that of comparable commercial instruments, yet offers better performance and greater versatility.

Data collection and simulation of high range resolution laser radar for surface mine detection

NASA Astrophysics Data System (ADS)

Steinvall, Ove; Chevalier, Tomas; Larsson, Håkan

2006-05-01

Rapid and efficient detection of surface mines, IED's (Improvised Explosive Devices) and UXO (Unexploded Ordnance) is of high priority in military conflicts. High range resolution laser radars combined with passive hyper/multispectral sensors offer an interesting concept to help solving this problem. This paper reports on laser radar data collection of various surface mines in different types of terrain. In order to evaluate the capability of 3D imaging for detecting and classifying the objects of interest a scanning laser radar was used to scan mines and surrounding terrain with high angular and range resolution. These data were then fed into a laser radar model capable of generating range waveforms for a variety of system parameters and combinations of different targets and backgrounds. We can thus simulate a potential system by down sampling to relevant pixel sizes and laser/receiver characteristics. Data, simulations and examples will be presented.

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

Huang X. R.; Siddons D.; Macrander, A.T.

Realization of x-ray Fabry-Perot (FP) resonance in back-Bragg-reflection crystal cavities has been proposed and explored for many years, but to date no satisfactory performance has been achieved. Here we show that single-cavity crystal resonators intrinsically have limited finesse and efficiency. To break this limit, we demonstrate that monolithic multicavity resonators with equal-width cavities and specific plate thickness ratios can generate ultrahigh-resolution FP resonance with high efficiency, steep peak tails, and ultrahigh contrast simultaneously. The resonance mechanism is similar to that of sequentially cascaded single-cavity resonators. The ultranarrow-bandwidth FP resonance is anticipated to have various applications, including modern ultrahigh-resolution or precisionmore » x-ray monochromatization, spectroscopy, coherence purification, coherent diffraction, phase contrast imaging, etc.« less

Performance of a high-resolution depth-encoding PET detector module using linearly-graded SiPM arrays

NASA Astrophysics Data System (ADS)

Du, Junwei; Bai, Xiaowei; Gola, Alberto; Acerbi, Fabio; Ferri, Alessandro; Piemonte, Claudio; Yang, Yongfeng; Cherry, Simon R.

2018-02-01

The goal of this study was to exploit the excellent spatial resolution characteristics of a position-sensitive silicon photomultiplier (SiPM) and develop a high-resolution depth-of-interaction (DOI) encoding positron emission tomography (PET) detector module. The detector consists of a 30  ×  30 array of 0.445  ×  0.445  ×  20 mm3 polished LYSO crystals coupled to two 15.5  ×  15.5 mm2 linearly-graded SiPM (LG-SiPM) arrays at both ends. The flood histograms show that all the crystals in the LYSO array can be resolved. The energy resolution, the coincidence timing resolution and the DOI resolution were 21.8  ±  5.8%, 1.23  ±  0.10 ns and 3.8  ±  1.2 mm, respectively, at a temperature of -10 °C and a bias voltage of 35.0 V. The performance did not degrade significantly for event rates of up to 130 000 counts s-1. This detector represents an attractive option for small-bore PET scanner designs that simultaneously emphasize high spatial resolution and high detection efficiency, important, for example, in preclinical imaging of the rodent brain with neuroreceptor ligands.

Discontinuous pH gradient-mediated separation of TiO2-enriched phosphopeptides

PubMed Central

Park, Sung-Soo; Maudsley, Stuart

2010-01-01

Global profiling of phosphoproteomes has proven a great challenge due to the relatively low stoichiometry of protein phosphorylation and poor ionization efficiency in mass spectrometers. Effective, physiologically-relevant, phosphoproteome research relies on the efficient phosphopeptide enrichment from complex samples. Immobilized metal affinity chromatography and titanium dioxide chromatography (TOC) can greatly assist selective phosphopeptide enrichment. However, the complexity of resultant enriched samples is often still high, suggesting that further separation of enriched phosphopeptides is required. We have developed a pH-gradient elution technique for enhanced phosphopeptide identification in conjunction with TOC. Using this process, we have demonstrated its superiority to the traditional ‘one-pot’ strategies for differential protein identification. Our technique generated a highly specific separation of phosphopeptides by an applied pH-gradient between 9.2 and 11.3. The most efficient elution range for high-resolution phosphopeptide separation was between pH 9.2 and 9.4. High-resolution separation of multiply-phosphorylated peptides was primarily achieved using elution ranges > pH 9.4. Investigation of phosphopeptide sequences identified in each pH fraction indicated that phosphopeptides with phosphorylated residues proximal to acidic residues, including glutamic acid, aspartic acid, and other phosphorylated residues, were preferentially eluted at higher pH values. PMID:20946866

The Development of a Scanning Soft X-Ray Microscope.

NASA Astrophysics Data System (ADS)

Rarback, Harvey Miles

We have developed a scanning soft X-ray microscope, which can be used to image natural biological specimens at high resolution and with less damage than electron microscopy. The microscope focuses a monochromatic beam of synchrotron radiation to a nearly diffraction limited spot with the aid of a high resolution Fresnel zone plate, specially fabricated for us at the IBM Watson Research Center. The specimen at one atmosphere is mechanically scanned through the spot and the transmitted radiation is efficiently detected with a flow proportional counter. A computer forms a realtime transmission image of the specimen which is displayed on a color monitor. Our first generation optics have produced images of natural wet specimens at a resolution of 300 nm.

A depth-of-interaction PET detector using mutual gain-equalized silicon photomultiplier

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

W. Xi, A.G, Weisenberger, H. Dong, Brian Kross, S. Lee, J. McKisson, Carl Zorn

We developed a prototype high resolution, high efficiency depth-encoding detector for PET applications based on dual-ended readout of LYSO array with two silicon photomultipliers (SiPMs). Flood images, energy resolution, and depth-of-interaction (DOI) resolution were measured for a LYSO array - 0.7 mm in crystal pitch and 10 mm in thickness - with four unpolished parallel sides. Flood images were obtained such that individual crystal element in the array is resolved. The energy resolution of the entire array was measured to be 33%, while individual crystal pixel elements utilizing the signal from both sides ranged from 23.3% to 27%. By applyingmore » a mutual-gain equalization method, a DOI resolution of 2 mm for the crystal array was obtained in the experiments while simulations indicate {approx}1 mm DOI resolution could possibly be achieved. The experimental DOI resolution can be further improved by obtaining revised detector supporting electronics with better energy resolutions. This study provides a detailed detector calibration and DOI response characterization of the dual-ended readout SiPM-based PET detectors, which will be important in the design and calibration of a PET scanner in the future.« less

An Example-Based Super-Resolution Algorithm for Selfie Images

PubMed Central

William, Jino Hans; Venkateswaran, N.; Narayanan, Srinath; Ramachandran, Sandeep

2016-01-01

A selfie is typically a self-portrait captured using the front camera of a smartphone. Most state-of-the-art smartphones are equipped with a high-resolution (HR) rear camera and a low-resolution (LR) front camera. As selfies are captured by front camera with limited pixel resolution, the fine details in it are explicitly missed. This paper aims to improve the resolution of selfies by exploiting the fine details in HR images captured by rear camera using an example-based super-resolution (SR) algorithm. HR images captured by rear camera carry significant fine details and are used as an exemplar to train an optimal matrix-value regression (MVR) operator. The MVR operator serves as an image-pair priori which learns the correspondence between the LR-HR patch-pairs and is effectively used to super-resolve LR selfie images. The proposed MVR algorithm avoids vectorization of image patch-pairs and preserves image-level information during both learning and recovering process. The proposed algorithm is evaluated for its efficiency and effectiveness both qualitatively and quantitatively with other state-of-the-art SR algorithms. The results validate that the proposed algorithm is efficient as it requires less than 3 seconds to super-resolve LR selfie and is effective as it preserves sharp details without introducing any counterfeit fine details. PMID:27064500

Noninvasive detection of coronary artery wall thickening with age in healthy subjects using high resolution MRI with beat-to-beat respiratory motion correction.

PubMed

Scott, Andrew D; Keegan, Jennifer; Mohiaddin, Raad H; Firmin, David N

2011-10-01

To demonstrate coronary artery wall thickening with age in a small healthy cohort using a highly efficient, reliable, and reproducible high-resolution MR technique. A 3D cross-sectional MR vessel wall images (0.7 × 0.7 × 3 mm resolution) with retrospective beat-to-beat respiratory motion correction (B2B-RMC) were obtained in the proximal right coronary artery of 21 healthy subjects (age, 22-62 years) with no known cardiovascular disease. Lumen and outer wall (lumen + vessel wall) areas were measured in one central slice from each subject and average wall thickness and wall area/outer wall area ratio (W/OW) calculated. Imaging was successful in 18 (86%) subjects with average respiratory efficiency 99.3 ± 1.7%. Coronary vessel wall thickness and W/OW significantly correlate with subject age, increasing by 0.088 mm and 0.031 per decade respectively (R = 0.53, P = 0.024 and R = 0.48, P = 0.046). No relationship was found between lumen area and vessel wall thickness (P = NS), but outer wall area increased significantly with vessel wall thickness at 19 mm(2) per mm (P = 0.046). This is consistent with outward vessel wall remodeling. Despite the small size of our healthy cohort, using high-resolution MR imaging and B2B-RMC, we have demonstrated increasing coronary vessel wall thickness and W/OW with age. The results obtained are consistent with outward vessel wall remodeling. Copyright © 2011 Wiley-Liss, Inc.

Iterative Nonlinear Tikhonov Algorithm with Constraints for Electromagnetic Tomography

NASA Technical Reports Server (NTRS)

Xu, Feng; Deshpande, Manohar

2012-01-01

Low frequency electromagnetic tomography such as the capacitance tomography (ECT) has been proposed for monitoring and mass-gauging of gas-liquid two-phase system under microgravity condition in NASA's future long-term space missions. Due to the ill-posed inverse problem of ECT, images reconstructed using conventional linear algorithms often suffer from limitations such as low resolution and blurred edges. Hence, new efficient high resolution nonlinear imaging algorithms are needed for accurate two-phase imaging. The proposed Iterative Nonlinear Tikhonov Regularized Algorithm with Constraints (INTAC) is based on an efficient finite element method (FEM) forward model of quasi-static electromagnetic problem. It iteratively minimizes the discrepancy between FEM simulated and actual measured capacitances by adjusting the reconstructed image using the Tikhonov regularized method. More importantly, it enforces the known permittivity of two phases to the unknown pixels which exceed the reasonable range of permittivity in each iteration. This strategy does not only stabilize the converging process, but also produces sharper images. Simulations show that resolution improvement of over 2 times can be achieved by INTAC with respect to conventional approaches. Strategies to further improve spatial imaging resolution are suggested, as well as techniques to accelerate nonlinear forward model and thus increase the temporal resolution.

Hard X-ray and gamma-ray imaging spectroscopy for the next solar maximum

NASA Technical Reports Server (NTRS)

Hudson, H. S.; Crannell, C. J.; Dennis, B. R.; Spicer, D. S.; Davis, J. M.; Hurford, G. J.; Lin, R. P.

1990-01-01

The objectives and principles are described of a single spectroscopic imaging package that can provide effective imaging in the hard X- and gamma-ray ranges. Called the High-Energy Solar Physics (HESP) mission instrument for solar investigation, the device is based on rotating modulation collimators with germanium semiconductor spectrometers. The instrument is planned to incorporate thick modulation plates, and the range of coverage is discussed. The optics permit the coverage of high-contrast hard X-ray images from small- and medium-sized flares with large signal-to-noise ratios. The detectors allow angular resolution of less than 1 arcsec, time resolution of less than 1 arcsec, and spectral resolution of about 1 keV. The HESP package is considered an effective and important instrument for investigating the high-energy solar events of the near-term future efficiently.

Beyond RGB: Very high resolution urban remote sensing with multimodal deep networks

NASA Astrophysics Data System (ADS)

Audebert, Nicolas; Le Saux, Bertrand; Lefèvre, Sébastien

2018-06-01

In this work, we investigate various methods to deal with semantic labeling of very high resolution multi-modal remote sensing data. Especially, we study how deep fully convolutional networks can be adapted to deal with multi-modal and multi-scale remote sensing data for semantic labeling. Our contributions are threefold: (a) we present an efficient multi-scale approach to leverage both a large spatial context and the high resolution data, (b) we investigate early and late fusion of Lidar and multispectral data, (c) we validate our methods on two public datasets with state-of-the-art results. Our results indicate that late fusion make it possible to recover errors steaming from ambiguous data, while early fusion allows for better joint-feature learning but at the cost of higher sensitivity to missing data.

Under the Microscope: Single-Domain Antibodies for Live-Cell Imaging and Super-Resolution Microscopy.

PubMed

Traenkle, Bjoern; Rothbauer, Ulrich

2017-01-01

Single-domain antibodies (sdAbs) have substantially expanded the possibilities of advanced cellular imaging such as live-cell or super-resolution microscopy to visualize cellular antigens and their dynamics. In addition to their unique properties including small size, high stability, and solubility in many environments, sdAbs can be efficiently functionalized according to the needs of the respective imaging approach. Genetically encoded intrabodies fused to fluorescent proteins (chromobodies) have become versatile tools to study dynamics of endogenous proteins in living cells. Additionally, sdAbs conjugated to organic dyes were shown to label cellular structures with high density and minimal fluorophore displacement making them highly attractive probes for super-resolution microscopy. Here, we review recent advances of the chromobody technology to visualize localization and dynamics of cellular targets and the application of chromobody-based cell models for compound screening. Acknowledging the emerging importance of super-resolution microscopy in cell biology, we further discuss advantages and challenges of sdAbs for this technology.

Implementing Photodissociation in an Orbitrap Mass Spectrometer

PubMed Central

Vasicek, Lisa A.; Ledvina, Aaron R.; Shaw, Jared; Griep-Raming, Jens; Westphall, Michael S.; Coon, Joshua J.; Brodbelt, Jennifer S.

2011-01-01

We modified a dual pressure linear ion trap Orbitrap to permit infrared multiphoton dissociation (IRMPD) in the higher energy collisional dissociation (HCD) cell for high resolution analysis. A number of parameters, including the pressures of the C-trap and HCD cell, the radio frequency (rf) amplitude applied to the C-trap, and the HCD DC offset, were evaluated to optimize IRMPD efficiency and maintain a high signal-to-noise ratio. IRMPD was utilized for characterization of phosphopeptides, supercharged peptides, and N-terminal modified peptides, as well as for top-down protein analysis. The high resolution and high mass accuracy capabilities of the Orbitrap analyzer facilitated confident assignment of product ions arising from IRMPD. PMID:21953052

CUBES: cassegrain U-band Brazil-ESO spectrograph

NASA Astrophysics Data System (ADS)

Barbuy, B.; Bawden Macanhan, V.; Bristow, P.; Castilho, B.; Dekker, H.; Delabre, B.; Diaz, M.; Gneiding, C.; Kerber, F.; Kuntschner, H.; La Mura, G.; Maciel, W.; Meléndez, J.; Pasquini, L.; Pereira, C. B.; Petitjean, P.; Reiss, R.; Siqueira-Mello, C.; Smiljanic, R.; Vernet, J.

2014-11-01

CUBES is a high-efficiency, medium-resolution ( R˜20,000) ground based UV (300-400 nm) spectrograph, to be installed in the cassegrain focus of one of ESO's VLT unit telescopes in 2017/18. The CUBES project is a joint venture between ESO and IAG/USP, and LNA/MCTI. CUBES will provide access to a wealth of new and relevant information for stellar as well as extragalactic sources. Main science cases include the study of beryllium and heavy elements in metal-poor stars, the direct determination of carbon, nitrogen and oxygen abundances by study of molecular bands in the UV range, as well as the study of active galactic nuclei and the quasar absorption lines. With a streamlined modern instrument design, high efficiency dispersing elements and UV-sensitive detectors, it will give a significant gain in sensitivity over existing ground based medium-high resolution spectrographs, enabling vastly increased sample sizes accessible to the astronomical community. We present here a brief overview of the project including the status, science cases and a discussion of the design options.

[Rapid detection of hot spot mutations of FGFR3 gene with PCR-high resolution melting assay].

PubMed

Li, Shan; Wang, Han; Su, Hua; Gao, Jinsong; Zhao, Xiuli

2017-08-10

To identify the causative mutations in five individuals affected with dyschondroplasia and develop an efficient procedure for detecting hot spot mutations of the FGFR3 gene. Genomic DNA was extracted from peripheral blood samples with a standard phenol/chloroform method. PCR-Sanger sequencing was used to analyze the causative mutations in the five probands. PCR-high resolution melting (HRM) was developed to detect the identified mutations. A c.1138G>A mutation in exon 8 was found in 4 probands, while a c.1620C>G mutation was found in exon 11 of proband 5 whom had a mild phenotype. All patients were successfully distinguished from healthy controls with the PCR-HRM method. The results of HRM analysis were highly consistent with that of Sanger sequencing. The Gly380Arg and Asn540Lys are hot spot mutations of the FGFR3 gene among patients with ACH/HCH. PCR-HRM analysis is more efficient for detecting hot spot mutations of the FGFR3 gene.

Two-photon imaging in living brain slices.

PubMed

Mainen, Z F; Maletic-Savatic, M; Shi, S H; Hayashi, Y; Malinow, R; Svoboda, K

1999-06-01

Two-photon excitation laser scanning microscopy (TPLSM) has become the tool of choice for high-resolution fluorescence imaging in intact neural tissues. Compared with other optical techniques, TPLSM allows high-resolution imaging and efficient detection of fluorescence signal with minimal photobleaching and phototoxicity. The advantages of TPLSM are especially pronounced in highly scattering environments such as the brain slice. Here we describe our approaches to imaging various aspects of synaptic function in living brain slices. To combine several imaging modes together with patch-clamp electrophysiological recordings we found it advantageous to custom-build an upright microscope. Our design goals were primarily experimental convenience and efficient collection of fluorescence. We describe our TPLSM imaging system and its performance in detail. We present dynamic measurements of neuronal morphology of neurons expressing green fluorescent protein (GFP) and GFP fusion proteins as well as functional imaging of calcium dynamics in individual dendritic spines. Although our microscope is a custom instrument, its key advantages can be easily implemented as a modification of commercial laser scanning microscopes. Copyright 1999 Academic Press.

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

Bose, Sownak; Li, Baojiu; He, Jian-hua

We describe and demonstrate the potential of a new and very efficient method for simulating certain classes of modified gravity theories, such as the widely studied f ( R ) gravity models. High resolution simulations for such models are currently very slow due to the highly nonlinear partial differential equation that needs to be solved exactly to predict the modified gravitational force. This nonlinearity is partly inherent, but is also exacerbated by the specific numerical algorithm used, which employs a variable redefinition to prevent numerical instabilities. The standard Newton-Gauss-Seidel iterative method used to tackle this problem has a poor convergencemore » rate. Our new method not only avoids this, but also allows the discretised equation to be written in a form that is analytically solvable. We show that this new method greatly improves the performance and efficiency of f ( R ) simulations. For example, a test simulation with 512{sup 3} particles in a box of size 512 Mpc/ h is now 5 times faster than before, while a Millennium-resolution simulation for f ( R ) gravity is estimated to be more than 20 times faster than with the old method. Our new implementation will be particularly useful for running very high resolution, large-sized simulations which, to date, are only possible for the standard model, and also makes it feasible to run large numbers of lower resolution simulations for covariance analyses. We hope that the method will bring us to a new era for precision cosmological tests of gravity.« less

Speeding up N-body simulations of modified gravity: chameleon screening models

NASA Astrophysics Data System (ADS)

Bose, Sownak; Li, Baojiu; Barreira, Alexandre; He, Jian-hua; Hellwing, Wojciech A.; Koyama, Kazuya; Llinares, Claudio; Zhao, Gong-Bo

2017-02-01

We describe and demonstrate the potential of a new and very efficient method for simulating certain classes of modified gravity theories, such as the widely studied f(R) gravity models. High resolution simulations for such models are currently very slow due to the highly nonlinear partial differential equation that needs to be solved exactly to predict the modified gravitational force. This nonlinearity is partly inherent, but is also exacerbated by the specific numerical algorithm used, which employs a variable redefinition to prevent numerical instabilities. The standard Newton-Gauss-Seidel iterative method used to tackle this problem has a poor convergence rate. Our new method not only avoids this, but also allows the discretised equation to be written in a form that is analytically solvable. We show that this new method greatly improves the performance and efficiency of f(R) simulations. For example, a test simulation with 5123 particles in a box of size 512 Mpc/h is now 5 times faster than before, while a Millennium-resolution simulation for f(R) gravity is estimated to be more than 20 times faster than with the old method. Our new implementation will be particularly useful for running very high resolution, large-sized simulations which, to date, are only possible for the standard model, and also makes it feasible to run large numbers of lower resolution simulations for covariance analyses. We hope that the method will bring us to a new era for precision cosmological tests of gravity.

A Variable-Resolution Stretched-Grid General Circulation Model and Data Assimilation System with Multiple Areas of Interest: Studying the Anomalous Regional Climate Events of 1998

NASA Technical Reports Server (NTRS)

Fox-Rabinovitz, Michael S.; Takacs, Lawrence; Govindaraju, Ravi C.; Atlas, Robert (Technical Monitor)

2002-01-01

The new stretched-grid design with multiple (four) areas of interest, one at each global quadrant, is implemented into both a stretched-grid GCM (general circulation model) and a stretched-grid data assimilation system (DAS). The four areas of interest include: the U.S./Northern Mexico, the El Nino area/Central South America, India/China, and the Eastern Indian Ocean/Australia. Both the stretched-grid GCM and DAS annual (November 1997 through December 1998) integrations are performed with 50 km regional resolution. The efficient regional down-scaling to mesoscales is obtained for each of the four areas of interest while the consistent interactions between regional and global scales and the high quality of global circulation, are preserved. This is the advantage of the stretched-grid approach. The global variable resolution DAS incorporating the stretched-grid GCM has been developed and tested as an efficient tool for producing regional analyses and diagnostics with enhanced mesoscale resolution. The anomalous regional climate events of 1998 that occurred over the U.S., Mexico, South America, China, India, African Sahel, and Australia are investigated in both simulation and data assimilation modes. Tree assimilated products are also used, along with gauge precipitation data, for validating the simulation results. The obtained results show that the stretched-grid GCM and DAS are capable of producing realistic high quality simulated and assimilated products at mesoscale resolution for regional climate studies and applications.

UV superconducting nanowire single-photon detectors with high efficiency, low noise, and 4 K operating temperature

NASA Astrophysics Data System (ADS)

Wollman, E. E.; Verma, V. B.; Beyer, A. D.; Briggs, R. M.; Korzh, B.; Allmaras, J. P.; Marsili, F.; Lita, A. E.; Mirin, R. P.; Nam, S. W.; Shaw, M. D.

2017-10-01

For photon-counting applications at ultraviolet wavelengths, there are currently no detectors that combine high efficiency (> 50%), sub-nanosecond timing resolution, and sub-Hz dark count rates. Superconducting nanowire single-photon detectors (SNSPDs) have seen success over the past decade for photon-counting applications in the near-infrared, but little work has been done to optimize SNSPDs for wavelengths below 400 nm. Here, we describe the design, fabrication, and characterization of UV SNSPDs operating at wavelengths between 250 and 370 nm. The detectors have active areas up to 56 ${\\mu}$m in diameter, 70 - 80% efficiency, timing resolution down to 60 ps FWHM, blindness to visible and infrared photons, and dark count rates of ~ 0.25 counts/hr for a 56 ${\\mu}$m diameter pixel. By using the amorphous superconductor MoSi, these UV SNSPDs are also able to operate at temperatures up to 4.2 K. These performance metrics make UV SNSPDs ideal for applications in trapped-ion quantum information processing, lidar studies of the upper atmosphere, UV fluorescent-lifetime imaging microscopy, and photon-starved UV astronomy.

Microfluidic co-flow of Newtonian and viscoelastic fluids for high-resolution separation of microparticles.

PubMed

Tian, Fei; Zhang, Wei; Cai, Lili; Li, Shanshan; Hu, Guoqing; Cong, Yulong; Liu, Chao; Li, Tiejun; Sun, Jiashu

2017-09-12

The microfluidic passive control of microparticles largely relies on the hydrodynamic effects of the carrier media such as Newtonian fluids and viscoelastic fluids. Yet the viscoelastic/Newtonian interfacial effect has been scarcely investigated, especially for high-resolution particle separation. Here we report a microfluidic co-flow of Newtonian (water or PBS) and viscoelastic fluids (PEO) for the size-dependent separation of microparticles. The co-flow condition generates a stable viscoelastic/Newtonian interface, giving rise to the wall-directed elastic lift forces that compete with the center-directed lift forces, and efficiently hinders the migration of microparticles from the Newtonian to the viscoelastic fluid in a size-dependent manner. An almost complete separation of a binary mixture of 1 μm and 2 μm polystyrene particles is achieved by the co-flow of water and a very dilute PEO solution (100 ppm), whereas the sole use of water or PEO could not lead to an efficient separation. This co-flow microfluidic system is also applied for the separation of Staphylococcus aureus (1 μm) from platelets (2-3 μm) with >90% efficiencies and purities.

Ultrahigh-speed X-ray imaging of hypervelocity projectiles

NASA Astrophysics Data System (ADS)

Miller, Stuart; Singh, Bipin; Cool, Steven; Entine, Gerald; Campbell, Larry; Bishel, Ron; Rushing, Rick; Nagarkar, Vivek V.

2011-08-01

High-speed X-ray imaging is an extremely important modality for healthcare, industrial, military and research applications such as medical computed tomography, non-destructive testing, imaging in-flight projectiles, characterizing exploding ordnance, and analyzing ballistic impacts. We report on the development of a modular, ultrahigh-speed, high-resolution digital X-ray imaging system with large active imaging area and microsecond time resolution, capable of acquiring at a rate of up to 150,000 frames per second. The system is based on a high-resolution, high-efficiency, and fast-decay scintillator screen optically coupled to an ultra-fast image-intensified CCD camera designed for ballistic impact studies and hypervelocity projectile imaging. A specially designed multi-anode, high-fluence X-ray source with 50 ns pulse duration provides a sequence of blur-free images of hypervelocity projectiles traveling at speeds exceeding 8 km/s (18,000 miles/h). This paper will discuss the design, performance, and high frame rate imaging capability of the system.

40 CFR Appendix B to Part 50 - Reference Method for the Determination of Suspended Particulate Matter in the Atmosphere (High...

Code of Federal Regulations, 2013 CFR

2013-07-01

... filters used are specified to have a minimum collection efficiency of 99 percent for 0.3 µm (DOP... electronic timers have much better set-point resolution than mechanical timers, but require a battery backup... Collection efficiency: 99 percent minimum as measured by the DOP test (ASTM-2986) for particles of 0.3 µm...

40 CFR Appendix B to Part 50 - Reference Method for the Determination of Suspended Particulate Matter in the Atmosphere (High...

Code of Federal Regulations, 2014 CFR

2014-07-01

... filters used are specified to have a minimum collection efficiency of 99 percent for 0.3 µm (DOP... electronic timers have much better set-point resolution than mechanical timers, but require a battery backup... Collection efficiency: 99 percent minimum as measured by the DOP test (ASTM-2986) for particles of 0.3 µm...

Application of Enhanced Sampling Monte Carlo Methods for High-Resolution Protein-Protein Docking in Rosetta

PubMed Central

Zhang, Zhe; Schindler, Christina E. M.; Lange, Oliver F.; Zacharias, Martin

2015-01-01

The high-resolution refinement of docked protein-protein complexes can provide valuable structural and mechanistic insight into protein complex formation complementing experiment. Monte Carlo (MC) based approaches are frequently applied to sample putative interaction geometries of proteins including also possible conformational changes of the binding partners. In order to explore efficiency improvements of the MC sampling, several enhanced sampling techniques, including temperature or Hamiltonian replica exchange and well-tempered ensemble approaches, have been combined with the MC method and were evaluated on 20 protein complexes using unbound partner structures. The well-tempered ensemble method combined with a 2-dimensional temperature and Hamiltonian replica exchange scheme (WTE-H-REMC) was identified as the most efficient search strategy. Comparison with prolonged MC searches indicates that the WTE-H-REMC approach requires approximately 5 times fewer MC steps to identify near native docking geometries compared to conventional MC searches. PMID:26053419

Precision Viticulture from Multitemporal, Multispectral Very High Resolution Satellite Data

NASA Astrophysics Data System (ADS)

Kandylakis, Z.; Karantzalos, K.

2016-06-01

In order to exploit efficiently very high resolution satellite multispectral data for precision agriculture applications, validated methodologies should be established which link the observed reflectance spectra with certain crop/plant/fruit biophysical and biochemical quality parameters. To this end, based on concurrent satellite and field campaigns during the veraison period, satellite and in-situ data were collected, along with several grape samples, at specific locations during the harvesting period. These data were collected for a period of three years in two viticultural areas in Northern Greece. After the required data pre-processing, canopy reflectance observations, through the combination of several vegetation indices were correlated with the quantitative results from the grape/must analysis of grape sampling. Results appear quite promising, indicating that certain key quality parameters (like brix levels, total phenolic content, brix to total acidity, anthocyanin levels) which describe the oenological potential, phenolic composition and chromatic characteristics can be efficiently estimated from the satellite data.

New developments in fabrication of high-energy-resolution analyzers for inelastic x-ray spectroscopy.

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

Said, A. H.; Sinn, H.; Divan, R.

2011-05-01

In this work new improvements related to the fabrication of spherical bent analyzers for 1 meV energy-resolution inelastic X-ray scattering spectroscopy are presented. The new method includes the use of a two-dimensional bender to achieve the required radius of curvature for X-ray analyzers. The advantage of this method is the ability to monitor the focus during bending, which leads to higher-efficiency analyzers.

High-throughput analysis of yeast replicative aging using a microfluidic system

PubMed Central

Jo, Myeong Chan; Liu, Wei; Gu, Liang; Dang, Weiwei; Qin, Lidong

2015-01-01

Saccharomyces cerevisiae has been an important model for studying the molecular mechanisms of aging in eukaryotic cells. However, the laborious and low-throughput methods of current yeast replicative lifespan assays limit their usefulness as a broad genetic screening platform for research on aging. We address this limitation by developing an efficient, high-throughput microfluidic single-cell analysis chip in combination with high-resolution time-lapse microscopy. This innovative design enables, to our knowledge for the first time, the determination of the yeast replicative lifespan in a high-throughput manner. Morphological and phenotypical changes during aging can also be monitored automatically with a much higher throughput than previous microfluidic designs. We demonstrate highly efficient trapping and retention of mother cells, determination of the replicative lifespan, and tracking of yeast cells throughout their entire lifespan. Using the high-resolution and large-scale data generated from the high-throughput yeast aging analysis (HYAA) chips, we investigated particular longevity-related changes in cell morphology and characteristics, including critical cell size, terminal morphology, and protein subcellular localization. In addition, because of the significantly improved retention rate of yeast mother cell, the HYAA-Chip was capable of demonstrating replicative lifespan extension by calorie restriction. PMID:26170317

Development of the fast and efficient gamma detector using Cherenkov light for TOF-PET

NASA Astrophysics Data System (ADS)

Canot, C.; Alokhina, M.; Abbon, P.; Bard, J. P.; Tauzin, G.; Yvon, D.; Sharyy, V.

2017-12-01

In this paper we present two configurations of innovative gamma detectors using Cherenkov light for time-of-flight—Positron Emission Tomography (PET). The first uses heavy crystals as a Cherenkov radiator to develop a demonstrator for a whole body PET scanner with high detection efficiency. We demonstrated a 30% detection efficiency and a 180 ps (FWHM) time resolution, mainly limited by the time transit spread of the photomultiplier. The second configuration uses an innovative liquid, the TriMethyl Bismuth, to develop a high precision brain-scanning PET device with time-of-flight capability. According to Geant4 simulation, we expect to reach a precision of 150 ps (FWHM) and an efficiency of about 25%.

Broadband high resolution X-ray spectral analyzer

DOEpatents

Silver, Eric H.; Legros, Mark; Madden, Norm W.; Goulding, Fred; Landis, Don

1998-01-01

A broad bandwidth high resolution x-ray fluorescence spectrometer has a performance that is superior in many ways to those currently available. It consists of an array of 4 large area microcalorimeters with 95% quantum efficiency at 6 keV and it produces x-ray spectra between 0.2 keV and 7 keV with an energy resolution of 7 to 10 eV. The resolution is obtained at input count rates per array element of 10 to 50 Hz in real-time, with analog pulse processing and thermal pile-up rejection. This performance cannot be matched by currently available x-ray spectrometers. The detectors are incorporated into a compact and portable cryogenic refrigerator system that is ready for use in many analytical spectroscopy applications as a tool for x-ray microanalysis or in research applications such as laboratory and astrophysical x-ray and particle spectroscopy.

Broadband high resolution X-ray spectral analyzer

DOEpatents

Silver, E.H.; Legros, M.; Madden, N.W.; Goulding, F.; Landis, D.

1998-07-07

A broad bandwidth high resolution X-ray fluorescence spectrometer has a performance that is superior in many ways to those currently available. It consists of an array of 4 large area microcalorimeters with 95% quantum efficiency at 6 keV and it produces X-ray spectra between 0.2 keV and 7 keV with an energy resolution of 7 to 10 eV. The resolution is obtained at input count rates per array element of 10 to 50 Hz in real-time, with analog pulse processing and thermal pile-up rejection. This performance cannot be matched by currently available X-ray spectrometers. The detectors are incorporated into a compact and portable cryogenic refrigerator system that is ready for use in many analytical spectroscopy applications as a tool for X-ray microanalysis or in research applications such as laboratory and astrophysical X-ray and particle spectroscopy. 6 figs.

Improving Spectroscopic Performance of a Coplanar-Anode High-Pressure Xenon Gamma-Ray Spectrometer

NASA Astrophysics Data System (ADS)

Kiff, Scott Douglas; He, Zhong; Tepper, Gary C.

2007-08-01

High-pressure xenon (HPXe) gas is a desirable radiation detection medium for homeland security applications because of its good inherent room-temperature energy resolution, potential for large, efficient devices, and stability over a broad temperature range. Past work in HPXe has produced large-diameter gridded ionization chambers with energy resolution at 662 keV between 3.5 and 4% FWHM. However, one major limitation of these detectors is resolution degradation due to Frisch grid microphonics. A coplanar-anode HPXe detector has been developed as an alternative to gridded chambers. An investigation of this detector's energy resolution is reported in this submission. A simulation package is used to investigate the contributions of important physical processes to the measured photopeak broadening. Experimental data is presented for pure Xe and Xe + 0.2%H2 mixtures, including an analysis of interaction location effects on the energy spectrum.

A lower limit to the accretion disc radius in the low-luminosity AGNNGC 1052 derived from high-angular resolution data

NASA Astrophysics Data System (ADS)

Reb, Lennart; Fernández-Ontiveros, Juan A.; Prieto, M. Almudena; Dolag, Klaus

2018-07-01

We investigate the central sub-arcsec region of the low-luminosity active galactic nucleusNGC 1052, using a high-angular resolution data set that covers 10 orders of magnitude in frequency. This allows us to infer the continuum emission within the innermost ˜17 pc around the black hole to be of non-thermal, synchrotron origin and to set a limit to the maximum contribution of a standard accretion disc. Assuming the canonical 10 per cent mass-light conversion efficiency for the standard accretion disc, its inferred accretion power would be too low by one order of magnitude to account for the observed continuum luminosity. We thus introduce a truncated accretion disc and derive a truncation radius to mass-light conversion efficiency relation, which we use to reconcile the inferred accretion power with the continuum luminosity. As a result we find that a disc providing the necessary accretion power must be truncated at rtr ≳ 26 rg, consistent with the inner radius derived from the observations of the Fe Kα line in the X-ray spectrum of this nucleus. This is the first time to derive a limit on the truncation radius of the accretion disc from high-angular resolution data only.

A lower limit to the accretion disc radius in the low-luminosity AGN NGC 1052 derived from high-angular resolution data

NASA Astrophysics Data System (ADS)

Reb, Lennart; Fernández-Ontiveros, Juan A.; Prieto, M. Almudena; Dolag, Klaus

2018-05-01

We investigate the central sub-arcsec region of the low-luminosity active galactic nucleus NGC 1052, using a high-angular resolution dataset that covers 10 orders of magnitude in frequency. This allows us to infer the continuum emission within the innermost ˜17 pc around the black hole to be of non-thermal, synchrotron origin and to set a limit to the maximum contribution of a standard accretion disc. Assuming the canonical 10 per cent mass-light conversion efficiency for the standard accretion disc, its inferred accretion power would be too low by one order of magnitude to account for the observed continuum luminosity. We thus introduce a truncated accretion disc and derive a truncation radius to mass-light conversion efficiency relation, which we use to reconcile the inferred accretion power with the continuum luminosity. As a result we find that a truncated disc providing the necessary accretion power must be truncated at rtr ≳ 26 rg, consistent with the inner radius derived from the observations of the Fe Kα line in the X-ray spectrum of this nucleus. This is the first time to derive a limit on the truncation radius of the accretion disc from high-angular resolution data only.

A Subsystem Test Bed for Chinese Spectral Radioheliograph

NASA Astrophysics Data System (ADS)

Zhao, An; Yan, Yihua; Wang, Wei

2014-11-01

The Chinese Spectral Radioheliograph is a solar dedicated radio interferometric array that will produce high spatial resolution, high temporal resolution, and high spectral resolution images of the Sun simultaneously in decimetre and centimetre wave range. Digital processing of intermediate frequency signal is an important part in a radio telescope. This paper describes a flexible and high-speed digital down conversion system for the CSRH by applying complex mixing, parallel filtering, and extracting algorithms to process IF signal at the time of being designed and incorporates canonic-signed digit coding and bit-plane method to improve program efficiency. The DDC system is intended to be a subsystem test bed for simulation and testing for CSRH. Software algorithms for simulation and hardware language algorithms based on FPGA are written which use less hardware resources and at the same time achieve high performances such as processing high-speed data flow (1 GHz) with 10 MHz spectral resolution. An experiment with the test bed is illustrated by using geostationary satellite data observed on March 20, 2014. Due to the easy alterability of the algorithms on FPGA, the data can be recomputed with different digital signal processing algorithms for selecting optimum algorithm.

High-spatial-resolution nanoparticle x-ray fluorescence tomography

NASA Astrophysics Data System (ADS)

Larsson, Jakob C.; Vâgberg, William; Vogt, Carmen; Lundström, Ulf; Larsson, Daniel H.; Hertz, Hans M.

2016-03-01

X-ray fluorescence tomography (XFCT) has potential for high-resolution 3D molecular x-ray bio-imaging. In this technique the fluorescence signal from targeted nanoparticles (NPs) is measured, providing information about the spatial distribution and concentration of the NPs inside the object. However, present laboratory XFCT systems typically have limited spatial resolution (>1 mm) and suffer from long scan times and high radiation dose even at high NP concentrations, mainly due to low efficiency and poor signal-to-noise ratio. We have developed a laboratory XFCT system with high spatial resolution (sub-100 μm), low NP concentration and vastly decreased scan times and dose, opening up the possibilities for in-vivo small-animal imaging research. The system consists of a high-brightness liquid-metal-jet microfocus x-ray source, x-ray focusing optics and an energy-resolving photon-counting detector. By using the source's characteristic 24 keV line-emission together with carefully matched molybdenum nanoparticles the Compton background is greatly reduced, increasing the SNR. Each measurement provides information about the spatial distribution and concentration of the Mo nanoparticles. A filtered back-projection method is used to produce the final XFCT image.

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

NASA Astrophysics Data System (ADS)

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

2016-06-01

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

Evaluation of high resolution ultrasound as a tool for assessing the 3D volume of blood clots during in vitro thrombolysis.

PubMed

Auboire, Laurent; Escoffre, Jean-Michel; Fouan, Damien; Jacquet, Jean-René; Ossant, Frédéric; Grégoire, Jean-Marc; Bouakaz, Ayache

2017-07-24

Thrombosis is a major cause of several diseases, i.e. myocardial infarction, cerebral stroke and pulmonary embolism. Thrombolytic therapies are required to induce fast and efficient recanalization of occluded vessels. To evaluate the in vitro efficacy of these thrombolytic strategies, measuring clot dissolution is essential. This study aimed to evaluate and validate high resolution ultrasound as a tool to assess the exact volume of clots in 3D and in real time during in vitro thrombolytic drug testing. This new method was validated by measuring the effects of concentration range of recombinant tissue type plasminogen activator on a blood clot during complete occlusion or 70% stenosis of a vessel. This study shows that high resolution ultrasound imaging allows for a real-time assessment of the 3D volume of a blood clot with negligible inter- and intra-operator variabilities. The conclusions drawn from this study demonstrate the promising potential of high resolution ultrasound imaging for the in vitro assessment of new thrombolytic drugs.

Computational Burden Resulting from Image Recognition of High Resolution Radar Sensors

PubMed Central

López-Rodríguez, Patricia; Fernández-Recio, Raúl; Bravo, Ignacio; Gardel, Alfredo; Lázaro, José L.; Rufo, Elena

2013-01-01

This paper presents a methodology for high resolution radar image generation and automatic target recognition emphasizing the computational cost involved in the process. In order to obtain focused inverse synthetic aperture radar (ISAR) images certain signal processing algorithms must be applied to the information sensed by the radar. From actual data collected by radar the stages and algorithms needed to obtain ISAR images are revised, including high resolution range profile generation, motion compensation and ISAR formation. Target recognition is achieved by comparing the generated set of actual ISAR images with a database of ISAR images generated by electromagnetic software. High resolution radar image generation and target recognition processes are burdensome and time consuming, so to determine the most suitable implementation platform the analysis of the computational complexity is of great interest. To this end and since target identification must be completed in real time, computational burden of both processes the generation and comparison with a database is explained separately. Conclusions are drawn about implementation platforms and calculation efficiency in order to reduce time consumption in a possible future implementation. PMID:23609804

Computational burden resulting from image recognition of high resolution radar sensors.

PubMed

López-Rodríguez, Patricia; Fernández-Recio, Raúl; Bravo, Ignacio; Gardel, Alfredo; Lázaro, José L; Rufo, Elena

2013-04-22

This paper presents a methodology for high resolution radar image generation and automatic target recognition emphasizing the computational cost involved in the process. In order to obtain focused inverse synthetic aperture radar (ISAR) images certain signal processing algorithms must be applied to the information sensed by the radar. From actual data collected by radar the stages and algorithms needed to obtain ISAR images are revised, including high resolution range profile generation, motion compensation and ISAR formation. Target recognition is achieved by comparing the generated set of actual ISAR images with a database of ISAR images generated by electromagnetic software. High resolution radar image generation and target recognition processes are burdensome and time consuming, so to determine the most suitable implementation platform the analysis of the computational complexity is of great interest. To this end and since target identification must be completed in real time, computational burden of both processes the generation and comparison with a database is explained separately. Conclusions are drawn about implementation platforms and calculation efficiency in order to reduce time consumption in a possible future implementation.

A multiresolution halftoning algorithm for progressive display

NASA Astrophysics Data System (ADS)

Mukherjee, Mithun; Sharma, Gaurav

2005-01-01

We describe and implement an algorithmic framework for memory efficient, 'on-the-fly' halftoning in a progressive transmission environment. Instead of a conventional approach which repeatedly recalls the continuous tone image from memory and subsequently halftones it for display, the proposed method achieves significant memory efficiency by storing only the halftoned image and updating it in response to additional information received through progressive transmission. Thus the method requires only a single frame-buffer of bits for storage of the displayed binary image and no additional storage is required for the contone data. The additional image data received through progressive transmission is accommodated through in-place updates of the buffer. The method is thus particularly advantageous for high resolution bi-level displays where it can result in significant savings in memory. The proposed framework is implemented using a suitable multi-resolution, multi-level modification of error diffusion that is motivated by the presence of a single binary frame-buffer. Aggregates of individual display bits constitute the multiple output levels at a given resolution. This creates a natural progression of increasing resolution with decreasing bit-depth.

Fabricating binary optics: An overview of binary optics process technology

NASA Technical Reports Server (NTRS)

Stern, Margaret B.

1993-01-01

A review of binary optics processing technology is presented. Pattern replication techniques have been optimized to generate high-quality efficient microoptics in visible and infrared materials. High resolution optical photolithography and precision alignment is used to fabricate maximally efficient fused silica diffractive microlenses at lambda = 633 nm. The degradation in optical efficiency of four-phase-level fused silica microlenses resulting from an intentional 0.35 micron translational error has been systematically measured as a function of lens speed (F/2 - F/60). Novel processes necessary for high sag refractive IR microoptics arrays, including deep anisotropic Si-etching, planarization of deep topography and multilayer resist techniques, are described. Initial results are presented for monolithic integration of photonic and microoptic systems.

Reflective type objective based spectral-domain phase-sensitive optical coherence tomography for high-sensitive structural and functional imaging of cochlear microstructures through intact bone of an excised guinea pig cochlea

NASA Astrophysics Data System (ADS)

Subhash, Hrebesh M.; Wang, Ruikang K.; Chen, Fangyi; Nuttall, Alfred L.

2013-03-01

Most of the optical coherence tomographic (OCT) systems for high resolution imaging of biological specimens are based on refractive type microscope objectives, which are optimized for specific wave length of the optical source. In this study, we present the feasibility of using commercially available reflective type objective for high sensitive and high resolution structural and functional imaging of cochlear microstructures of an excised guinea pig through intact temporal bone. Unlike conventional refractive type microscopic objective, reflective objective are free from chromatic aberrations due to their all-reflecting nature and can support a broadband of spectrum with very high light collection efficiency.

Liquid Crystal on Silicon Wavefront Corrector

NASA Technical Reports Server (NTRS)

Pouch, John; Miranda, Felix; Wang, Xinghua; Bos, Philip, J.

2004-01-01

A low cost, high resolution, liquid crystal on silicon, spatial light modulator has been developed for the correction of huge aberrations in an optical system where the polarization dependence and the chromatic nature are tolerated. However, the overall system performance suggests that this device is also suitable for real time correction of aberration in human eyes. This device has a resolution of 1024 x 768, and is driven by an XGA display driver. The effective stroke length of the device is 700 nm and 2000 nm for the visible and IR regions of the device, respectively. The response speeds are 50 Hz and 5 Hz, respectively, which are fast enough for real time adaptive optics for aberrations in human eyes. By modulating a wavefront of 2 pi, this device can correct for arbitrary high order wavefront aberrations since the 2-D pixel array is independently controlled by the driver. The high resolution and high accuracy of the device allow for diffraction limited correction of the tip and tilt or defocus without an additional correction loop. We have shown that for every wave of aberration, an 8 step blazed grating is required to achieve high diffraction efficiency around 80%. In light of this, up to 125 waves peak to valley of tip and tilt can be corrected if we choose the simplest aberration. Corrections of 34 waves of aberration, including high order Zernicke terms in a high magnification telescope, to diffraction limited performance (residual wavefront aberration less than 1/30 lambda at 632.8 nm) have been observed at high efficiency.

Efficient photonic reformatting of celestial light for diffraction-limited spectroscopy

NASA Astrophysics Data System (ADS)

MacLachlan, D. G.; Harris, R. J.; Gris-Sánchez, I.; Morris, T. J.; Choudhury, D.; Gendron, E.; Basden, A. G.; Spaleniak, I.; Arriola, A.; Birks, T. A.; Allington-Smith, J. R.; Thomson, R. R.

2017-02-01

The spectral resolution of a dispersive astronomical spectrograph is limited by the trade-off between throughput and the width of the entrance slit. Photonic guided wave transitions have been proposed as a route to bypass this trade-off, by enabling the efficient reformatting of incoherent seeing-limited light collected by the telescope into a linear array of single modes: a pseudo-slit which is highly multimode in one axis but diffraction-limited in the dispersion axis of the spectrograph. It is anticipated that the size of a single-object spectrograph fed with light in this manner would be essentially independent of the telescope aperture size. A further anticipated benefit is that such spectrographs would be free of `modal noise', a phenomenon that occurs in high-resolution multimode fibre-fed spectrographs due to the coherent nature of the telescope point spread function (PSF). We seek to address these aspects by integrating a multicore fibre photonic lantern with an ultrafast laser inscribed three-dimensional waveguide interconnect to spatially reformat the modes within the PSF into a diffraction-limited pseudo-slit. Using the CANARY adaptive optics (AO) demonstrator on the William Herschel Telescope, and 1530 ± 80 nm stellar light, the device exhibits a transmission of 47-53 per cent depending upon the mode of AO correction applied. We also show the advantage of using AO to couple light into such a device by sampling only the core of the CANARY PSF. This result underscores the possibility that a fully optimized guided-wave device can be used with AO to provide efficient spectroscopy at high spectral resolution.

Multi-Depth-Map Raytracing for Efficient Large-Scene Reconstruction.

PubMed

Arikan, Murat; Preiner, Reinhold; Wimmer, Michael

2016-02-01

With the enormous advances of the acquisition technology over the last years, fast processing and high-quality visualization of large point clouds have gained increasing attention. Commonly, a mesh surface is reconstructed from the point cloud and a high-resolution texture is generated over the mesh from the images taken at the site to represent surface materials. However, this global reconstruction and texturing approach becomes impractical with increasing data sizes. Recently, due to its potential for scalability and extensibility, a method for texturing a set of depth maps in a preprocessing and stitching them at runtime has been proposed to represent large scenes. However, the rendering performance of this method is strongly dependent on the number of depth maps and their resolution. Moreover, for the proposed scene representation, every single depth map has to be textured by the images, which in practice heavily increases processing costs. In this paper, we present a novel method to break these dependencies by introducing an efficient raytracing of multiple depth maps. In a preprocessing phase, we first generate high-resolution textured depth maps by rendering the input points from image cameras and then perform a graph-cut based optimization to assign a small subset of these points to the images. At runtime, we use the resulting point-to-image assignments (1) to identify for each view ray which depth map contains the closest ray-surface intersection and (2) to efficiently compute this intersection point. The resulting algorithm accelerates both the texturing and the rendering of the depth maps by an order of magnitude.

CscoreTool: fast Hi-C compartment analysis at high resolution.

PubMed

Zheng, Xiaobin; Zheng, Yixian

2018-05-01

The genome-wide chromosome conformation capture (Hi-C) has revealed that the eukaryotic genome can be partitioned into A and B compartments that have distinctive chromatin and transcription features. Current Principle Component Analyses (PCA)-based method for the A/B compartment prediction based on Hi-C data requires substantial CPU time and memory. We report the development of a method, CscoreTool, which enables fast and memory-efficient determination of A/B compartments at high resolution even in datasets with low sequencing depth. https://github.com/scoutzxb/CscoreTool. xzheng@carnegiescience.edu. Supplementary data are available at Bioinformatics online.

Recent advances in small molecule OLED-on-silicon microdisplays

NASA Astrophysics Data System (ADS)

Ghosh, Amalkumar P.; Ali, Tariq A.; Khayrullin, Ilyas; Vazan, Fridrich; Prache, Olivier F.; Wacyk, Ihor

2009-08-01

High resolution OLED-on-silicon microdisplay technology is unique and challenging since it requires very small subpixel dimensions (~ 2-5 microns). eMagin's OLED microdisplay is based on white top emitter architecture using small molecule organic materials. The devices are fabricated using high Tg materials. The devices are hermetically sealed with vacuum deposited thin film layers. LCD-type color filters are patterned using photolithography methods to generate primary R, G, B colors. Results of recent improvements in the OLED-on-silicon microdisplay technology, with emphasis on efficiencies, lifetimes, grey scale and CIE color coordinates for SVGA and SXGA resolution microdisplays is presented.

Satellite image time series simulation for environmental monitoring

NASA Astrophysics Data System (ADS)

Guo, Tao

2014-11-01

The performance of environmental monitoring heavily depends on the availability of consecutive observation data and it turns out an increasing demand in remote sensing community for satellite image data in the sufficient resolution with respect to both spatial and temporal requirements, which appear to be conflictive and hard to tune tradeoffs. Multiple constellations could be a solution if without concerning cost, and thus it is so far interesting but very challenging to develop a method which can simultaneously improve both spatial and temporal details. There are some research efforts to deal with the problem from various aspects, a type of approaches is to enhance the spatial resolution using techniques of super resolution, pan-sharpen etc. which can produce good visual effects, but mostly cannot preserve spectral signatures and result in losing analytical value. Another type is to fill temporal frequency gaps by adopting time interpolation, which actually doesn't increase informative context at all. In this paper we presented a novel method to generate satellite images in higher spatial and temporal details, which further enables satellite image time series simulation. Our method starts with a pair of high-low resolution data set, and then a spatial registration is done by introducing LDA model to map high and low resolution pixels correspondingly. Afterwards, temporal change information is captured through a comparison of low resolution time series data, and the temporal change is then projected onto high resolution data plane and assigned to each high resolution pixel referring the predefined temporal change patterns of each type of ground objects to generate a simulated high resolution data. A preliminary experiment shows that our method can simulate a high resolution data with a good accuracy. We consider the contribution of our method is to enable timely monitoring of temporal changes through analysis of low resolution images time series only, and usage of costly high resolution data can be reduced as much as possible, and it presents an efficient solution with great cost performance to build up an economically operational monitoring service for environment, agriculture, forest, land use investigation, and other applications.

Investigating the origin of efficiency droop by profiling the temperature across the multi-quantum well of an operating light-emitting diode

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

Jung, Euihan; Hwang, Gwangseok; Chung, Jaehun

2015-01-26

Performance degradation resulting from efficiency droop during high-power operation is a critical problem in the development of high-efficiency light-emitting diodes (LEDs). In order to resolve the efficiency droop and increase the external quantum efficiency of LEDs, the droop's origin should be identified first. To experimentally investigate the cause of efficiency droop, we used null-point scanning thermal microscopy to quantitatively profile the temperature distribution on the cross section of the epi-layers of an operating GaN-based vertical LED with nanoscale spatial resolution at four different current densities. The movement of temperature peak towards the p-GaN side as the current density increases suggestsmore » that more heat is generated by leakage current than by Auger recombination. We therefore suspect that at higher current densities, current leakage becomes the dominant cause of the droop problem.« less

Sources and pathways of the upscale effects on the Southern Hemisphere jet in MPAS-CAM4 variable-resolution simulations

DOE PAGES

Sakaguchi, Koichi; Lu, Jian; Leung, L. Ruby; ...

2016-10-22

Impacts of regional grid refinement on large-scale circulations (“upscale effects”) were detected in a previous study that used the Model for Prediction Across Scales-Atmosphere coupled to the physics parameterizations of the Community Atmosphere Model version 4. The strongest upscale effect was identified in the Southern Hemisphere jet during austral winter. This study examines the detailed underlying processes by comparing two simulations at quasi-uniform resolutions of 30 and 120 km to three variable-resolution simulations in which the horizontal grids are regionally refined to 30 km in North America, South America, or Asia from 120 km elsewhere. In all the variable-resolution simulations,more » precipitation increases in convective areas inside the high-resolution domains, as in the reference quasi-uniform high-resolution simulation. With grid refinement encompassing the tropical Americas, the increased condensational heating expands the local divergent circulations (Hadley cell) meridionally such that their descending branch is shifted poleward, which also pushes the baroclinically unstable regions, momentum flux convergence, and the eddy-driven jet poleward. This teleconnection pathway is not found in the reference high-resolution simulation due to a strong resolution sensitivity of cloud radiative forcing that dominates the aforementioned teleconnection signals. The regional refinement over Asia enhances Rossby wave sources and strengthens the upper level southerly flow, both facilitating the cross-equatorial propagation of stationary waves. Evidence indicates that this teleconnection pathway is also found in the reference high-resolution simulation. Lastly, the result underlines the intricate diagnoses needed to understand the upscale effects in global variable-resolution simulations, with implications for science investigations using the computationally efficient modeling framework.« less

Sources and pathways of the upscale effects on the Southern Hemisphere jet in MPAS-CAM4 variable-resolution simulations

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

Sakaguchi, Koichi; Lu, Jian; Leung, L. Ruby

Impacts of regional grid refinement on large-scale circulations (“upscale effects”) were detected in a previous study that used the Model for Prediction Across Scales-Atmosphere coupled to the physics parameterizations of the Community Atmosphere Model version 4. The strongest upscale effect was identified in the Southern Hemisphere jet during austral winter. This study examines the detailed underlying processes by comparing two simulations at quasi-uniform resolutions of 30 and 120 km to three variable-resolution simulations in which the horizontal grids are regionally refined to 30 km in North America, South America, or Asia from 120 km elsewhere. In all the variable-resolution simulations,more » precipitation increases in convective areas inside the high-resolution domains, as in the reference quasi-uniform high-resolution simulation. With grid refinement encompassing the tropical Americas, the increased condensational heating expands the local divergent circulations (Hadley cell) meridionally such that their descending branch is shifted poleward, which also pushes the baroclinically unstable regions, momentum flux convergence, and the eddy-driven jet poleward. This teleconnection pathway is not found in the reference high-resolution simulation due to a strong resolution sensitivity of cloud radiative forcing that dominates the aforementioned teleconnection signals. The regional refinement over Asia enhances Rossby wave sources and strengthens the upper level southerly flow, both facilitating the cross-equatorial propagation of stationary waves. Evidence indicates that this teleconnection pathway is also found in the reference high-resolution simulation. Lastly, the result underlines the intricate diagnoses needed to understand the upscale effects in global variable-resolution simulations, with implications for science investigations using the computationally efficient modeling framework.« less

Roi-Orientated Sensor Correction Based on Virtual Steady Reimaging Model for Wide Swath High Resolution Optical Satellite Imagery

NASA Astrophysics Data System (ADS)

Zhu, Y.; Jin, S.; Tian, Y.; Wang, M.

2017-09-01

To meet the requirement of high accuracy and high speed processing for wide swath high resolution optical satellite imagery under emergency situation in both ground processing system and on-board processing system. This paper proposed a ROI-orientated sensor correction algorithm based on virtual steady reimaging model for wide swath high resolution optical satellite imagery. Firstly, the imaging time and spatial window of the ROI is determined by a dynamic search method. Then, the dynamic ROI sensor correction model based on virtual steady reimaging model is constructed. Finally, the corrected image corresponding to the ROI is generated based on the coordinates mapping relationship which is established by the dynamic sensor correction model for corrected image and rigours imaging model for original image. Two experimental results show that the image registration between panchromatic and multispectral images can be well achieved and the image distortion caused by satellite jitter can be also corrected efficiently.

Optical design of the PEPSI high-resolution spectrograph at LBT

NASA Astrophysics Data System (ADS)

Andersen, Michael I.; Spano, Paolo; Woche, Manfred; Strassmeier, Klaus G.; Beckert, Erik

2004-09-01

PEPSI is a high-resolution, fiber fed echelle spectrograph with polarimetric capabilities for the LBT. In order to reach a maximum resolution R=120.000 in polarimetric mode and 300.000 in integral light mode with high efficiency in the spectral range 390-1050~nm, we designed a white-pupil configuration with Maksutov collimators. Light is dispersed by an R4 31.6 lines/mm monolithic echelle grating mosaic and split into two arms through dichroics. The two arms, optimized for the spectral range 390-550~nm and 550-1050~nm, respectively, consist of Maksutov transfer collimators, VPH-grism cross dispersers, optimized dioptric cameras and 7.5K x 7.5K 8~μ CCDs. Fibers of different core sizes coupled to different image-slicers allow a high throughput, comparable to that of direct feed instruments. The optical configuration with only spherical and cylindrical surfaces, except for one aspherical surface in each camera, reduces costs and guarantees high optical quality. PEPSI is under construction at AIP with first light expected in 2006.

Accurate Monotonicity - Preserving Schemes With Runge-Kutta Time Stepping

NASA Technical Reports Server (NTRS)

Suresh, A.; Huynh, H. T.

1997-01-01

A new class of high-order monotonicity-preserving schemes for the numerical solution of conservation laws is presented. The interface value in these schemes is obtained by limiting a higher-order polynominal reconstruction. The limiting is designed to preserve accuracy near extrema and to work well with Runge-Kutta time stepping. Computational efficiency is enhanced by a simple test that determines whether the limiting procedure is needed. For linear advection in one dimension, these schemes are shown as well as the Euler equations also confirm their high accuracy, good shock resolution, and computational efficiency.

Design studies on the 4π γ-ray calorimeter for the ETF experiment at HIRFL-CSR

NASA Astrophysics Data System (ADS)

Yue, Ke; Xu, Hu-Shan; Sun, Zhi-Yu; Su, Guang-Hui; Wang, Jian-Song; Zheng, Chuan; Li, Song-Lin; Hu, Zheng-Guo; Chen, Rou-Fu; Xiao, Zhi-Gang; Hu, Qiang; Zhang, Xue-Ying; Yu, Yu-Hong; Chen, Jun-Ling

2011-01-01

A high detection efficiency calorimeter which is used to detect γ-rays with energies from 1 MeV up to 10 MeV as well as light charged particles has been proposed. Design of the geometry, results of the crystal tests and Monte Carlo simulations are presented in this paper. The simulation results confirm that the calorimeter can obtain high detection efficiency and good energy resolution with the current designed geometry. And the calorimeter is competent for the future External Target Facility (ETF) experiments.

The assembly, calibration, and preliminary results from the Colorado high-resolution Echelle stellar spectrograph (CHESS)

NASA Astrophysics Data System (ADS)

Hoadley, Keri; France, Kevin; Nell, Nicholas; Kane, Robert; Schultz, Ted; Beasley, Matthew; Green, James; Kulow, Jen; Kersgaard, Eliot; Fleming, Brian

2014-07-01

The Colorado High-resolution Echelle Stellar Spectrograph (CHESS) is a far ultraviolet (FUV) rocket-borne experiment designed to study the atomic-to-molecular transitions within translucent interstellar clouds. CHESS is an objective echelle spectrograph operating at f/12.4 and resolving power of 120,000 over a band pass of 100 - 160 nm. The echelle flight grating is the product of a research and development project with LightSmyth Inc. and was coated at Goddard Space Flight Center (GSFC) with Al+LiF. It has an empirically-determined groove density of 71.67 grooves/mm. At the Center for Astrophysics and Space Astronomy (CASA) at the University of Colorado (CU), we measured the efficiencies of the peak and adjacent dispersion orders throughout the 90 - 165 nm band pass to characterize the behavior of the grating for pre-flight calibrations and to assess the scattered-light behavior. The crossdispersing grating, developed and ruled by Horiba Jobin-Yvon, is a holographically-ruled, low line density (351 grooves/mm), powered optic with a toroidal surface curvature. The CHESS cross-disperser was also coated at GSFC; Cr+Al+LiF was deposited to enhance far-UV efficiency. Results from final efficiency and reflectivity measurements of both optics are presented. We utilize a cross-strip anode microchannel plate (MCP) detector built by Sensor Sciences to achieve high resolution (25 μm spatial resolution) and data collection rates (~ 106 photons/second) over a large format (40mm round, digitized to 8k x 8k) for the first time in an astronomical sounding rocket flight. The CHESS instrument was successfully launched from White Sands Missile Range on 24 May 2014. We present pre-flight sensitivity, effective area calculations, lab spectra and calibration results, and touch on first results and post-flight calibration plans.

Phytoplankton plasticity drives large variability in carbon fixation efficiency

NASA Astrophysics Data System (ADS)

Ayata, Sakina-Dorothée.; Lévy, Marina; Aumont, Olivier; Resplandy, Laure; Tagliabue, Alessandro; Sciandra, Antoine; Bernard, Olivier

2014-12-01

Phytoplankton C:N stoichiometry is highly flexible due to physiological plasticity, which could lead to high variations in carbon fixation efficiency (carbon consumption relative to nitrogen). However, the magnitude, as well as the spatial and temporal scales of variability, remains poorly constrained. We used a high-resolution biogeochemical model resolving various scales from small to high, spatially and temporally, in order to quantify and better understand this variability. We find that phytoplankton C:N ratio is highly variable at all spatial and temporal scales (5-12 molC/molN), from mesoscale to regional scale, and is mainly driven by nitrogen supply. Carbon fixation efficiency varies accordingly at all scales (±30%), with higher values under oligotrophic conditions and lower values under eutrophic conditions. Hence, phytoplankton plasticity may act as a buffer by attenuating carbon sequestration variability. Our results have implications for in situ estimations of C:N ratios and for future predictions under high CO2 world.

A comparison of select image-compression algorithms for an electronic still camera

NASA Technical Reports Server (NTRS)

Nerheim, Rosalee

1989-01-01

This effort is a study of image-compression algorithms for an electronic still camera. An electronic still camera can record and transmit high-quality images without the use of film, because images are stored digitally in computer memory. However, high-resolution images contain an enormous amount of information, and will strain the camera's data-storage system. Image compression will allow more images to be stored in the camera's memory. For the electronic still camera, a compression algorithm that produces a reconstructed image of high fidelity is most important. Efficiency of the algorithm is the second priority. High fidelity and efficiency are more important than a high compression ratio. Several algorithms were chosen for this study and judged on fidelity, efficiency and compression ratio. The transform method appears to be the best choice. At present, the method is compressing images to a ratio of 5.3:1 and producing high-fidelity reconstructed images.

Dual-resolution dose assessments for proton beamlet using MCNPX 2.6.0

NASA Astrophysics Data System (ADS)

Chao, T. C.; Wei, S. C.; Wu, S. W.; Tung, C. J.; Tu, S. J.; Cheng, H. W.; Lee, C. C.

2015-11-01

The purpose of this study is to access proton dose distribution in dual resolution phantoms using MCNPX 2.6.0. The dual resolution phantom uses higher resolution in Bragg peak, area near large dose gradient, or heterogeneous interface and lower resolution in the rest. MCNPX 2.6.0 was installed in Ubuntu 10.04 with MPI for parallel computing. FMesh1 tallies were utilized to record the energy deposition which is a special designed tally for voxel phantoms that converts dose deposition from fluence. 60 and 120 MeV narrow proton beam were incident into Coarse, Dual and Fine resolution phantoms with pure water, water-bone-water and water-air-water setups. The doses in coarse resolution phantoms are underestimated owing to partial volume effect. The dose distributions in dual or high resolution phantoms agreed well with each other and dual resolution phantoms were at least 10 times more efficient than fine resolution one. Because the secondary particle range is much longer in air than in water, the dose of low density region may be under-estimated if the resolution or calculation grid is not small enough.

Electronic and mechanical improvement of the receiving terminal of a free-space microwave power transmission system

NASA Technical Reports Server (NTRS)

Brown, W. C.

1977-01-01

Significant advancements were made in a number of areas: improved efficiency of basic receiving element at low power density levels, improved resolution and confidence in efficiency measurements mathematical modelling and computer simulation of the receiving element and the design, construction, and testing of an environmentally protected two-plane construction suitable for low cost, highly automated construction of large receiving arrays.

The Use of Scale-Dependent Precision to Increase Forecast Accuracy in Earth System Modelling

NASA Astrophysics Data System (ADS)

Thornes, Tobias; Duben, Peter; Palmer, Tim

2016-04-01

At the current pace of development, it may be decades before the 'exa-scale' computers needed to resolve individual convective clouds in weather and climate models become available to forecasters, and such machines will incur very high power demands. But the resolution could be improved today by switching to more efficient, 'inexact' hardware with which variables can be represented in 'reduced precision'. Currently, all numbers in our models are represented as double-precision floating points - each requiring 64 bits of memory - to minimise rounding errors, regardless of spatial scale. Yet observational and modelling constraints mean that values of atmospheric variables are inevitably known less precisely on smaller scales, suggesting that this may be a waste of computer resources. More accurate forecasts might therefore be obtained by taking a scale-selective approach whereby the precision of variables is gradually decreased at smaller spatial scales to optimise the overall efficiency of the model. To study the effect of reducing precision to different levels on multiple spatial scales, we here introduce a new model atmosphere developed by extending the Lorenz '96 idealised system to encompass three tiers of variables - which represent large-, medium- and small-scale features - for the first time. In this chaotic but computationally tractable system, the 'true' state can be defined by explicitly resolving all three tiers. The abilities of low resolution (single-tier) double-precision models and similar-cost high resolution (two-tier) models in mixed-precision to produce accurate forecasts of this 'truth' are compared. The high resolution models outperform the low resolution ones even when small-scale variables are resolved in half-precision (16 bits). This suggests that using scale-dependent levels of precision in more complicated real-world Earth System models could allow forecasts to be made at higher resolution and with improved accuracy. If adopted, this new paradigm would represent a revolution in numerical modelling that could be of great benefit to the world.

The usability of the optical parametric amplification of light for high-angular-resolution imaging and fast astrometry

NASA Astrophysics Data System (ADS)

Kurek, A. R.; Stachowski, A.; Banaszek, K.; Pollo, A.

2018-05-01

High-angular-resolution imaging is crucial for many applications in modern astronomy and astrophysics. The fundamental diffraction limit constrains the resolving power of both ground-based and spaceborne telescopes. The recent idea of a quantum telescope based on the optical parametric amplification (OPA) of light aims to bypass this limit for the imaging of extended sources by an order of magnitude or more. We present an updated scheme of an OPA-based device and a more accurate model of the signal amplification by such a device. The semiclassical model that we present predicts that the noise in such a system will form so-called light speckles as a result of light interference in the optical path. Based on this model, we analysed the efficiency of OPA in increasing the angular resolution of the imaging of extended targets and the precise localization of a distant point source. According to our new model, OPA offers a gain in resolved imaging in comparison to classical optics. For a given time-span, we found that OPA can be more efficient in localizing a single distant point source than classical telescopes.

Efficient Exploration of Membrane-Associated Phenomena at Atomic Resolution.

PubMed

Vermaas, Josh V; Baylon, Javier L; Arcario, Mark J; Muller, Melanie P; Wu, Zhe; Pogorelov, Taras V; Tajkhorshid, Emad

2015-06-01

Biological membranes constitute a critical component in all living cells. In addition to providing a conducive environment to a wide range of cellular processes, including transport and signaling, mounting evidence has established active participation of specific lipids in modulating membrane protein function through various mechanisms. Understanding lipid-protein interactions underlying these mechanisms at a sufficiently high resolution has proven extremely challenging, partly due to the semi-fluid nature of the membrane. In order to address this challenge computationally, multiple methods have been developed, including an alternative membrane representation termed highly mobile membrane mimetic (HMMM) in which lateral lipid diffusion has been significantly enhanced without compromising atomic details. The model allows for efficient sampling of lipid-protein interactions at atomic resolution, thereby significantly enhancing the effectiveness of molecular dynamics simulations in capturing membrane-associated phenomena. In this review, after providing an overview of HMMM model development, we will describe briefly successful application of the model to study a variety of membrane processes, including lipid-dependent binding and insertion of peripheral proteins, the mechanism of phospholipid insertion into lipid bilayers, and characterization of optimal tilt angle of transmembrane helices. We conclude with practical recommendations for proper usage of the model in simulation studies of membrane processes.

Testing of Front End Electronics for 10ps Time of Flight Detectors

NASA Astrophysics Data System (ADS)

Kimball, Matthew; EIC PID Consortium Collaboration

2016-09-01

To fully achieve the physics goals of the future Electron Ion Collider (EIC), continued development of the detectors involved is needed. One area of research involves improving the timing resolution of Time of Flight (ToF) detectors from 100ps to 10ps. When the timing resolution of these ToF detectors is improved, better particle identification can be achieved. In addition, as ToF detectors are being constructed with ever improving timing resolution, the need to improve the high speed performance of the fast electronics used in their front-end electronics (FEE) increases. A series of careful measurements has been performed to investigate the performance and efficiency of each element in the FEE chain. The focus of these tests lies on the amplitude transmission efficiency of the high speed signals as a function of frequency, also known as the bandwidth. The components tested include balanced to unbalanced (balun) boards, signal pre-amps, and waveform digitizers. These tests were performed on individual components and with all elements connected over a frequency range of 1MHz to 1GHz. The results of these tests will be presented. This research was supported by US DOE MENP Grant DE-FG02-03ER41243.

Reaction chemistry and collisional processes in multiple devices for resolving isobaric interferences in ICP-MS.

PubMed

Bandura, D R; Baranov, V I; Tanner, S D

2001-07-01

A low-level review of the fundamentals of ion-molecule interactions is presented. These interactions are used to predict the efficiencies of collisional fragmentation, energy damping and reaction for a variety of neutral gases as a function of pressure in a rf-driven collision/reaction cell. It is shown that the number of collisions increases dramatically when the ion energies are reduced to near-thermal (< 0.1 eV), because of the ion-induced dipole and ion-dipole interaction. These considerations suggest that chemical reaction can be orders of magnitude more efficient at improving the analyte signal/background ratio than can collisional fragmentation. Considerations that lead to an appropriate selection of type of gas, operating pressure, and ion energies for efficient operation of the cell for the alleviation of spectral interferences are discussed. High efficiency (large differences between reaction efficiencies of the analyte and interference ions, and concomitant suppression of secondary chemistry) might be required to optimize the chemical resolution (determination of an analyte in the presence of an isobaric interference) when using ion-molecule chemistry to suppress the interfering ion. In many instances atom transfer to the analyte, which shifts the analytical m/z by the mass of the atom transferred, provides high chemical resolution, even when the efficiency of reaction is relatively low. Examples are given of oxidation, hydroxylation, and chlorination of analyte ions (V+, Fe+, As+, Se+, Sr+, Y+, and Zr+) to improve the capability of determination of complex samples. Preliminary results are given showing O-atom abstraction by CO from CaO+ to enable the determination of Fe in high-Ca samples.

A fast and automatic mosaic method for high-resolution satellite images

NASA Astrophysics Data System (ADS)

Chen, Hongshun; He, Hui; Xiao, Hongyu; Huang, Jing

2015-12-01

We proposed a fast and fully automatic mosaic method for high-resolution satellite images. First, the overlapped rectangle is computed according to geographical locations of the reference and mosaic images and feature points on both the reference and mosaic images are extracted by a scale-invariant feature transform (SIFT) algorithm only from the overlapped region. Then, the RANSAC method is used to match feature points of both images. Finally, the two images are fused into a seamlessly panoramic image by the simple linear weighted fusion method or other method. The proposed method is implemented in C++ language based on OpenCV and GDAL, and tested by Worldview-2 multispectral images with a spatial resolution of 2 meters. Results show that the proposed method can detect feature points efficiently and mosaic images automatically.

High-Resolution Surface Reconstruction from Imagery for Close Range Cultural Heritage Applications

NASA Astrophysics Data System (ADS)

Wenzel, K.; Abdel-Wahab, M.; Cefalu, A.; Fritsch, D.

2012-07-01

The recording of high resolution point clouds with sub-mm resolution is a demanding and cost intensive task, especially with current equipment like handheld laser scanners. We present an image based approached, where techniques of image matching and dense surface reconstruction are combined with a compact and affordable rig of off-the-shelf industry cameras. Such cameras provide high spatial resolution with low radiometric noise, which enables a one-shot solution and thus an efficient data acquisition while satisfying high accuracy requirements. However, the largest drawback of image based solutions is often the acquisition of surfaces with low texture where the image matching process might fail. Thus, an additional structured light projector is employed, represented here by the pseudo-random pattern projector of the Microsoft Kinect. Its strong infrared-laser projects speckles of different sizes. By using dense image matching techniques on the acquired images, a 3D point can be derived for almost each pixel. The use of multiple cameras enables the acquisition of a high resolution point cloud with high accuracy for each shot. For the proposed system up to 3.5 Mio. 3D points with sub-mm accuracy can be derived per shot. The registration of multiple shots is performed by Structure and Motion reconstruction techniques, where feature points are used to derive the camera positions and rotations automatically without initial information.

Prospect of space-based interferometry at EUV and soft X-ray wavelengths

NASA Technical Reports Server (NTRS)

Welsh, Barry Y.; Chakrabarti, Supriya

1992-01-01

We review the current capabilities of high-resolution, spectroscopic, space-borne instrumentation available for both solar and stellar observations in the EUV and soft X-ray wavelength regimes, and describe the basic design of a compact, all-reflection interferometer based on the spatial heterodyne technique; this is capable of producing a resolving power (lambda/Delta-lambda) of about 20,000 in the 100-200 A region using presently available multilayer optical components. Such an instrument can be readily constructed with existing technology. Due to its small size and lack of moving parts, it is ideally suited to spaceborne applications. Based on best estimates of the efficiency of this instrument at soft X-ray wavelengths, we review the possible use of this high-resolution interferometer in obtaining high-resolution full-disk spectroscopy of the sun. We also discuss its possible use for observations of diffuse sources such as the EUV interstellar background radiation.

Ultrahigh pressure fast size exclusion chromatography for top-down proteomics.

PubMed

Chen, Xin; Ge, Ying

2013-09-01

Top-down MS-based proteomics has gained a solid growth over the past few years but still faces significant challenges in the LC separation of intact proteins. In top-down proteomics, it is essential to separate the high mass proteins from the low mass species due to the exponential decay in S/N as a function of increasing molecular mass. SEC is a favored LC method for size-based separation of proteins but suffers from notoriously low resolution and detrimental dilution. Herein, we reported the use of ultrahigh pressure (UHP) SEC for rapid and high-resolution separation of intact proteins for top-down proteomics. Fast separation of intact proteins (6-669 kDa) was achieved in < 7 min with high resolution and high efficiency. More importantly, we have shown that this UHP-SEC provides high-resolution separation of intact proteins using a MS-friendly volatile solvent system, allowing the direct top-down MS analysis of SEC-eluted proteins without an additional desalting step. Taken together, we have demonstrated that UHP-SEC is an attractive LC strategy for the size separation of proteins with great potential for top-down proteomics. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-performance liquid chromatography with fast-scanning fluorescence detection and multivariate curve resolution for the efficient determination of galantamine and its main metabolites in serum.

PubMed

Culzoni, María J; Aucelio, Ricardo Q; Escandar, Graciela M

2012-08-31

Based on green analytical chemistry principles, an efficient approach was applied for the simultaneous determination of galantamine, a widely used cholinesterase inhibitor for the treatment of Alzheimer's disease, and its major metabolites in serum samples. After a simple serum deproteinization step, second-order data were rapidly obtained (less than 6 min) with a chromatographic system operating in the isocratic regime using ammonium acetate/acetonitrile (94:6) as mobile phase. Detection was made with a fast-scanning spectrofluorimeter, which allowed the efficient collection of data to obtain matrices of fluorescence intensity as a function of retention time and emission wavelength. Successful resolution was achieved in the presence of matrix interferences in serum samples using multivariate curve resolution-alternating least-squares (MCR-ALS). The developed approach allows the quantification of the analytes at levels found in treated patients, without the need of applying either preconcentration or extraction steps. Limits of detection in the range between 8 and 11 ng mL(-1), relative prediction errors from 7 to 12% and coefficients of variation from 4 to 7% were achieved. Copyright © 2012 Elsevier B.V. All rights reserved.

Scanning laser beam displays based on a 2D MEMS

NASA Astrophysics Data System (ADS)

Niesten, Maarten; Masood, Taha; Miller, Josh; Tauscher, Jason

2010-05-01

The combination of laser light sources and MEMS technology enables a range of display systems such as ultra small projectors for mobile devices, head-up displays for vehicles, wearable near-eye displays and projection systems for 3D imaging. Images are created by scanning red, green and blue lasers horizontally and vertically with a single two-dimensional MEMS. Due to the excellent beam quality of laser beams, the optical designs are efficient and compact. In addition, the laser illumination enables saturated display colors that are desirable for augmented reality applications where a virtual image is used. With this technology, the smallest projector engine for high volume manufacturing to date has been developed. This projector module has a height of 7 mm and a volume of 5 cc. The resolution of this projector is WVGA. No additional projection optics is required, resulting in an infinite focus depth. Unlike with micro-display projection displays, an increase in resolution will not lead to an increase in size or a decrease in efficiency. Therefore future projectors can be developed that combine a higher resolution in an even smaller and thinner form factor with increased efficiencies that will lead to lower power consumption.

Resolution of ab initio shapes determined from small-angle scattering.

PubMed

Tuukkanen, Anne T; Kleywegt, Gerard J; Svergun, Dmitri I

2016-11-01

Spatial resolution is an important characteristic of structural models, and the authors of structures determined by X-ray crystallography or electron cryo-microscopy always provide the resolution upon publication and deposition. Small-angle scattering of X-rays or neutrons (SAS) has recently become a mainstream structural method providing the overall three-dimensional structures of proteins, nucleic acids and complexes in solution. However, no quantitative resolution measure is available for SAS-derived models, which significantly hampers their validation and further use. Here, a method is derived for resolution assessment for ab initio shape reconstruction from scattering data. The inherent variability of the ab initio shapes is utilized and it is demonstrated how their average Fourier shell correlation function is related to the model resolution. The method is validated against simulated data for proteins with known high-resolution structures and its efficiency is demonstrated in applications to experimental data. It is proposed that henceforth the resolution be reported in publications and depositions of ab initio SAS models.

Resolution of ab initio shapes determined from small-angle scattering

PubMed Central

Tuukkanen, Anne T.; Kleywegt, Gerard J.; Svergun, Dmitri I.

2016-01-01

Spatial resolution is an important characteristic of structural models, and the authors of structures determined by X-ray crystallography or electron cryo-microscopy always provide the resolution upon publication and deposition. Small-angle scattering of X-rays or neutrons (SAS) has recently become a mainstream structural method providing the overall three-dimensional structures of proteins, nucleic acids and complexes in solution. However, no quantitative resolution measure is available for SAS-derived models, which significantly hampers their validation and further use. Here, a method is derived for resolution assessment for ab initio shape reconstruction from scattering data. The inherent variability of the ab initio shapes is utilized and it is demonstrated how their average Fourier shell correlation function is related to the model resolution. The method is validated against simulated data for proteins with known high-resolution structures and its efficiency is demonstrated in applications to experimental data. It is proposed that henceforth the resolution be reported in publications and depositions of ab initio SAS models. PMID:27840683

Advanced materials for multilayer mirrors for extreme ultraviolet solar astronomy.

PubMed

Bogachev, S A; Chkhalo, N I; Kuzin, S V; Pariev, D E; Polkovnikov, V N; Salashchenko, N N; Shestov, S V; Zuev, S Y

2016-03-20

We provide an analysis of contemporary multilayer optics for extreme ultraviolet (EUV) solar astronomy in the wavelength ranges: λ=12.9-13.3  nm, λ=17-21  nm, λ=28-33  nm, and λ=58.4  nm. We found new material pairs, which will make new spaceborne experiments possible due to the high reflection efficiencies, spectral resolution, and long-term stabilities of the proposed multilayer coatings. In the spectral range λ=13  nm, Mo/Be multilayer mirrors were shown to demonstrate a better ratio of reflection efficiency and spectral resolution compared with the commonly used Mo/Si. In the spectral range λ=17-21  nm, a new multilayer structure Al/Si was proposed, which had higher spectral resolution along with comparable reflection efficiency compared with the commonly used Al/Zr multilayer structures. In the spectral range λ=30  nm, the Si/B₄C/Mg/Cr multilayer structure turned out to best obey reflection efficiency and long-term stability. The B₄C and Cr layers prevented mutual diffusion of the Si and Mg layers. For the spectral range λ=58  nm, a new multilayer Mo/Mg-based structure was developed; its reflection efficiency and long-term stability have been analyzed. We also investigated intrinsic stresses inherent for most of the multilayer structures and proposed possibilities for stress elimination.

The influence of spatially and temporally high-resolution wind forcing on the power input to near-inertial waves in the ocean

NASA Astrophysics Data System (ADS)

Rimac, Antonija; von Storch, Jin-Song; Eden, Carsten

2013-04-01

The estimated power required to sustain global general circulation in the ocean is about 2 TW. This power is supplied with wind stress and tides. Energy spectrum shows pronounced maxima at near-inertial frequency. Near-inertial waves excited by high-frequency winds represent an important source for deep ocean mixing since they can propagate into the deep ocean and dissipate far away from the generation sites. The energy input by winds to near-inertial waves has been studied mostly using slab ocean models and wind stress forcing with coarse temporal resolution (e.g. 6-hourly). Slab ocean models lack the ability to reproduce fundamental aspects of kinetic energy balance and systematically overestimate the wind work. Also, slab ocean models do not account the energy used for the mixed layer deepening or the energy radiating downward into the deep ocean. Coarse temporal resolution of the wind forcing strongly underestimates the near-inertial energy. To overcome this difficulty we use an eddy permitting ocean model with high-frequency wind forcing. We establish the following model setup: We use the Max Planck Institute Ocean Model (MPIOM) on a tripolar grid with 45 km horizontal resolution and 40 vertical levels. We run the model with wind forcings that vary in horizontal and temporal resolution. We use high-resolution (1-hourly with 35 km horizontal resolution) and low-resolution winds (6-hourly with 250 km horizontal resolution). We address the following questions: Is the kinetic energy of near-inertial waves enhanced when high-resolution wind forcings are used? If so, is this due to higher level of overall wind variability or higher spatial or temporal resolution of wind forcing? How large is the power of near-inertial waves generated by winds? Our results show that near-inertial waves are enhanced and the near-inertial kinetic energy is two times higher (in the storm track regions 3.5 times higher) when high-resolution winds are used. Filtering high-resolution winds in space and time, the near-inertial kinetic energy reduces. The reduction is faster when a temporal filter is used suggesting that the high-frequency wind forcing is more efficient in generating near-inertial wave energy than the small-scale wind forcing. Using low-resolution wind forcing the wind generated power to near-inertial waves is 0.55 TW. When we use high-resolution wind forcing the result is 1.6 TW meaning that the result increases by 300%.

Non-invasive measurement of frog skin reflectivity in high spatial resolution using a dual hyperspectral approach.

PubMed

Pinto, Francisco; Mielewczik, Michael; Liebisch, Frank; Walter, Achim; Greven, Hartmut; Rascher, Uwe

2013-01-01

Most spectral data for the amphibian integument are limited to the visible spectrum of light and have been collected using point measurements with low spatial resolution. In the present study a dual camera setup consisting of two push broom hyperspectral imaging systems was employed, which produces reflectance images between 400 and 2500 nm with high spectral and spatial resolution and a high dynamic range. We briefly introduce the system and document the high efficiency of this technique analyzing exemplarily the spectral reflectivity of the integument of three arboreal anuran species (Litoria caerulea, Agalychnis callidryas and Hyla arborea), all of which appear green to the human eye. The imaging setup generates a high number of spectral bands within seconds and allows non-invasive characterization of spectral characteristics with relatively high working distance. Despite the comparatively uniform coloration, spectral reflectivity between 700 and 1100 nm differed markedly among the species. In contrast to H. arborea, L. caerulea and A. callidryas showed reflection in this range. For all three species, reflectivity above 1100 nm is primarily defined by water absorption. Furthermore, the high resolution allowed examining even small structures such as fingers and toes, which in A. callidryas showed an increased reflectivity in the near infrared part of the spectrum. Hyperspectral imaging was found to be a very useful alternative technique combining the spectral resolution of spectrometric measurements with a higher spatial resolution. In addition, we used Digital Infrared/Red-Edge Photography as new simple method to roughly determine the near infrared reflectivity of frog specimens in field, where hyperspectral imaging is typically difficult.

Intracranial arterial wall imaging using three-dimensional high isotropic resolution black blood MRI at 3.0 Tesla.

PubMed

Qiao, Ye; Steinman, David A; Qin, Qin; Etesami, Maryam; Schär, Michael; Astor, Brad C; Wasserman, Bruce A

2011-07-01

To develop a high isotropic-resolution sequence to evaluate intracranial vessels at 3.0 Tesla (T). Thirteen healthy volunteers and 4 patients with intracranial stenosis were imaged at 3.0T using 0.5-mm isotropic-resolution three-dimensional (3D) Volumetric ISotropic TSE Acquisition (VISTA; TSE, turbo spin echo), with conventional 2D-TSE for comparison. VISTA was repeated for 6 volunteers and 4 patients at 0.4-mm isotropic-resolution to explore the trade-off between SNR and voxel volume. Wall signal-to-noise-ratio (SNR(wall) ), wall-lumen contrast-to-noise-ratio (CNR(wall-lumen) ), lumen area (LA), wall area (WA), mean wall thickness (MWT), and maximum wall thickness (maxWT) were compared between 3D-VISTA and 2D-TSE sequences, as well as 3D images acquired at both resolutions. Reliability was assessed by intraclass correlations (ICC). Compared with 2D-TSE measurements, 3D-VISTA provided 58% and 74% improvement in SNR(wall) and CNR(wall-lumen) , respectively. LA, WA, MWT and maxWT from 3D and 2D techniques highly correlated (ICCs of 0.96, 0.95, 0.96, and 0.91, respectively). CNR(wall-lumen) using 0.4-mm resolution VISTA decreased by 27%, compared with 0.5-mm VISTA but with reduced partial-volume-based overestimation of wall thickness. Reliability for 3D measurements was good to excellent. The 3D-VISTA provides SNR-efficient, highly reliable measurements of intracranial vessels at high isotropic-resolution, enabling broad coverage in a clinically acceptable time. Copyright © 2011 Wiley-Liss, Inc.

Compartmentalized Low-Rank Recovery for High-Resolution Lipid Unsuppressed MRSI

PubMed Central

Bhattacharya, Ipshita; Jacob, Mathews

2017-01-01

Purpose To introduce a novel algorithm for the recovery of high-resolution magnetic resonance spectroscopic imaging (MRSI) data with minimal lipid leakage artifacts, from dual-density spiral acquisition. Methods The reconstruction of MRSI data from dual-density spiral data is formulated as a compartmental low-rank recovery problem. The MRSI dataset is modeled as the sum of metabolite and lipid signals, each of which is support limited to the brain and extracranial regions, respectively, in addition to being orthogonal to each other. The reconstruction problem is formulated as an optimization problem, which is solved using iterative reweighted nuclear norm minimization. Results The comparisons of the scheme against dual-resolution reconstruction algorithm on numerical phantom and in vivo datasets demonstrate the ability of the scheme to provide higher spatial resolution and lower lipid leakage artifacts. The experiments demonstrate the ability of the scheme to recover the metabolite maps, from lipid unsuppressed datasets with echo time (TE)=55 ms. Conclusion The proposed reconstruction method and data acquisition strategy provide an efficient way to achieve high-resolution metabolite maps without lipid suppression. This algorithm would be beneficial for fast metabolic mapping and extension to multislice acquisitions. PMID:27851875

A review on high-resolution CMOS delay lines: towards sub-picosecond jitter performance.

PubMed

Abdulrazzaq, Bilal I; Abdul Halin, Izhal; Kawahito, Shoji; Sidek, Roslina M; Shafie, Suhaidi; Yunus, Nurul Amziah Md

2016-01-01

A review on CMOS delay lines with a focus on the most frequently used techniques for high-resolution delay step is presented. The primary types, specifications, delay circuits, and operating principles are presented. The delay circuits reported in this paper are used for delaying digital inputs and clock signals. The most common analog and digitally-controlled delay elements topologies are presented, focusing on the main delay-tuning strategies. IC variables, namely, process, supply voltage, temperature, and noise sources that affect delay resolution through timing jitter are discussed. The design specifications of these delay elements are also discussed and compared for the common delay line circuits. As a result, the main findings of this paper are highlighting and discussing the followings: the most efficient high-resolution delay line techniques, the trade-off challenge found between CMOS delay lines designed using either analog or digitally-controlled delay elements, the trade-off challenge between delay resolution and delay range and the proposed solutions for this challenge, and how CMOS technology scaling can affect the performance of CMOS delay lines. Moreover, the current trends and efforts used in order to generate output delayed signal with low jitter in the sub-picosecond range are presented.

SERS and integrative imaging upon internalization of quantum dots into human oral epithelial cells.

PubMed

Cepeda-Pérez, Elisa; López-Luke, Tzarara; Plascencia-Villa, Germán; Perez-Mayen, Leonardo; Ceja-Fdez, Andrea; Ponce, Arturo; Vivero-Escoto, Juan; de la Rosa, Elder

2016-07-01

CdTe quantum dots (QDs) are widely used in bio-applications due to their size and highly efficient optical properties. However internalization mechanisms thereof for the variety of freshly extracted, not cultivated human cells and their specific molecular interactions remains an open topic for discussion. In this study, we assess the internalization mechanism of CdTe quantum dots (3.3 nm) capped with thioglycolic acid using non cultivated oral epithelial cells obtained from healthy donors. Naked gold nanoparticles (40 nm) were successfully used as nanosensors for surface-enhanced Raman spectroscopy to efficiently identify characteristic Raman peaks, providing new evidence indicating that the first interactions of these QDs with epithelial cells occurred preferentially with aromatic rings and amine groups of amino acid residues and glycans from trans-membrane proteins and cytoskeleton. Using an integrative combination of advanced imaging techniques, including ultra-high resolution SEM, high resolution STEM coupled with EDX spectroscopy together with the results obtained by Raman spectroscopy, it was determined that thioglycolic acid capped CdTe QDs are efficiently internalized into freshly extracted oral epithelial cells only by facilitated diffusion, distributed into cytoplasm and even within the cell nucleus in three minutes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nano-antenna in a photoconductive photomixer for highly efficient continuous wave terahertz emission

PubMed Central

Tanoto, H.; Teng, J. H.; Wu, Q. Y.; Sun, M.; Chen, Z. N.; Maier, S. A.; Wang, B.; Chum, C. C.; Si, G. Y.; Danner, A. J.; Chua, S. J.

2013-01-01

We report highly efficient continuous-wave terahertz (THz) photoconductive antenna based photomixer employing nano-gap electrodes in the active region. The tip-to-tip nano-gap electrode structure provides strong THz field enhancement and acts as a nano-antenna to radiate the THz wave generated in the active region of the photomixer. In addition, it provides good impedance matching to the THz planar antenna and exhibits a lower RC time constant, allowing more efficient radiation especially at the higher part of the THz spectrum. As a result, the output intensity of the photomixer with the new nano-gap electrode structure in the active region is two orders of magnitude higher than that of a photomixer with typical interdigitated electrodes. Significant improvement in the THz emission bandwidth was also observed. An efficient continuous wave THz source will greatly benefit compact THz system development for high resolution THz spectroscopy and imaging applications. PMID:24100840

Sharp-Tip Silver Nanowires Mounted on Cantilevers for High-Aspect-Ratio High-Resolution Imaging.

PubMed

Ma, Xuezhi; Zhu, Yangzhi; Kim, Sanggon; Liu, Qiushi; Byrley, Peter; Wei, Yang; Zhang, Jin; Jiang, Kaili; Fan, Shoushan; Yan, Ruoxue; Liu, Ming

2016-11-09

Despite many efforts to fabricate high-aspect-ratio atomic force microscopy (HAR-AFM) probes for high-fidelity, high-resolution topographical imaging of three-dimensional (3D) nanostructured surfaces, current HAR probes still suffer from unsatisfactory performance, low wear-resistivity, and extravagant prices. The primary objective of this work is to demonstrate a novel design of a high-resolution (HR) HAR AFM probe, which is fabricated through a reliable, cost-efficient benchtop process to precisely implant a single ultrasharp metallic nanowire on a standard AFM cantilever probe. The force-displacement curve indicated that the HAR-HR probe is robust against buckling and bending up to 150 nN. The probes were tested on polymer trenches, showing a much better image fidelity when compared with standard silicon tips. The lateral resolution, when scanning a rough metal thin film and single-walled carbon nanotubes (SW-CNTs), was found to be better than 8 nm. Finally, stable imaging quality in tapping mode was demonstrated for at least 15 continuous scans indicating high resistance to wear. These results demonstrate a reliable benchtop fabrication technique toward metallic HAR-HR AFM probes with performance parallel or exceeding that of commercial HAR probes, yet at a fraction of their cost.

High-energy-resolution monochromator for nuclear resonant scattering of synchrotron radiation by Te-125 at 35.49 keV

NASA Astrophysics Data System (ADS)

Imai, Yasuhiko; Yoda, Yoshitaka; Kitao, Shinji; Masuda, Ryo; Higashitaniguchi, Satoshi; Inaba, Chika; Seto, Makoto

2007-09-01

We have developed a high-resolution monochromator (HRM) for the measurement of nuclear resonant scattering (NRS) of synchrotron radiation by Te-125 at 35.49 keV using the backscattering of sapphire (9 1 -10 68). HRMs for nuclei with excitation energies less than 30 keV have been successfully developed using high angle diffractions by silicon crystals. Nearly perfect silicon crystal, however, is not suitable for high efficient HRMs at higher energy regions because the symmetry of the crystal structure is high and the Debye-temperature is low. Therefore, we used high quality synthetic sapphire crystal, which has low symmetry of crystal structure and high Debye-temperature. The temperature of the crystal was precisely controlled around 218 K to diffract synchrotron radiation with a Bragg angle of π/2 - 0.52 mrad. Energy was tuned by changing the crystal temperature under the condition of constant diffraction angle. Energy resolution was measured by detecting nuclear forward scattering by Te-125 in enriched TeO II. The relative energy resolution of 2.1×10 -7 is achieved, that is 7.5 meV in energy bandwidth. This HRM opens studies on element-specific dynamics and electronic state of substances containing Te-125.

High-resolution x-ray imaging using a structured scintillator.

PubMed

Hormozan, Yashar; Sychugov, Ilya; Linnros, Jan

2016-02-01

In this study, the authors introduce a new generation of finely structured scintillators with a very high spatial resolution (a few micrometers) compared to conventional scintillators, yet maintaining a thick absorbing layer for improved detectivity. Their concept is based on a 2D array of high aspect ratio pores which are fabricated by ICP etching, with spacings (pitches) of a few micrometers, on silicon and oxidation of the pore walls. The pores were subsequently filled by melting of powdered CsI(Tl), as the scintillating agent. In order to couple the secondary emitted photons of the back of the scintillator array to a CCD device, having a larger pixel size than the pore pitch, an open optical microscope with adjustable magnification was designed and implemented. By imaging a sharp edge, the authors were able to calculate the modulation transfer function (MTF) of this finely structured scintillator. The x-ray images of individually resolved pores suggest that they have been almost uniformly filled, and the MTF measurements show the feasibility of a few microns spatial resolution imaging, as set by the scintillator pore size. Compared to existing techniques utilizing CsI needles as a structured scintillator, their results imply an almost sevenfold improvement in resolution. Finally, high resolution images, taken by their detector, are presented. The presented work successfully shows the functionality of their detector concept for high resolution imaging and further fabrication developments are most likely to result in higher quantum efficiencies.

High-resolution x-ray imaging using a structured scintillator

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

Hormozan, Yashar, E-mail: hormozan@kth.se; Sychugov, Ilya; Linnros, Jan

2016-02-15

Purpose: In this study, the authors introduce a new generation of finely structured scintillators with a very high spatial resolution (a few micrometers) compared to conventional scintillators, yet maintaining a thick absorbing layer for improved detectivity. Methods: Their concept is based on a 2D array of high aspect ratio pores which are fabricated by ICP etching, with spacings (pitches) of a few micrometers, on silicon and oxidation of the pore walls. The pores were subsequently filled by melting of powdered CsI(Tl), as the scintillating agent. In order to couple the secondary emitted photons of the back of the scintillator arraymore » to a CCD device, having a larger pixel size than the pore pitch, an open optical microscope with adjustable magnification was designed and implemented. By imaging a sharp edge, the authors were able to calculate the modulation transfer function (MTF) of this finely structured scintillator. Results: The x-ray images of individually resolved pores suggest that they have been almost uniformly filled, and the MTF measurements show the feasibility of a few microns spatial resolution imaging, as set by the scintillator pore size. Compared to existing techniques utilizing CsI needles as a structured scintillator, their results imply an almost sevenfold improvement in resolution. Finally, high resolution images, taken by their detector, are presented. Conclusions: The presented work successfully shows the functionality of their detector concept for high resolution imaging and further fabrication developments are most likely to result in higher quantum efficiencies.« less

Gridless, pattern-driven point cloud completion and extension

NASA Astrophysics Data System (ADS)

Gravey, Mathieu; Mariethoz, Gregoire

2016-04-01

While satellites offer Earth observation with a wide coverage, other remote sensing techniques such as terrestrial LiDAR can acquire very high-resolution data on an area that is limited in extension and often discontinuous due to shadow effects. Here we propose a numerical approach to merge these two types of information, thereby reconstructing high-resolution data on a continuous large area. It is based on a pattern matching process that completes the areas where only low-resolution data is available, using bootstrapped high-resolution patterns. Currently, the most common approach to pattern matching is to interpolate the point data on a grid. While this approach is computationally efficient, it presents major drawbacks for point clouds processing because a significant part of the information is lost in the point-to-grid resampling, and that a prohibitive amount of memory is needed to store large grids. To address these issues, we propose a gridless method that compares point clouds subsets without the need to use a grid. On-the-fly interpolation involves a heavy computational load, which is met by using a GPU high-optimized implementation and a hierarchical pattern searching strategy. The method is illustrated using data from the Val d'Arolla, Swiss Alps, where high-resolution terrestrial LiDAR data are fused with lower-resolution Landsat and WorldView-3 acquisitions, such that the density of points is homogeneized (data completion) and that it is extend to a larger area (data extension).

Time stamping of single optical photons with 10 ns resolution

NASA Astrophysics Data System (ADS)

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

2017-05-01

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

Design Studies of a CZT-based Detector Combined with a Pixel-Geometry-Matching Collimator for SPECT Imaging.

PubMed

Weng, Fenghua; Bagchi, Srijeeta; Huang, Qiu; Seo, Youngho

2013-10-01

Single Photon Emission Computed Tomography (SPECT) suffers limited efficiency due to the need for collimators. Collimator properties largely decide the data statistics and image quality. Various materials and configurations of collimators have been investigated in many years. The main thrust of our study is to evaluate the design of pixel-geometry-matching collimators to investigate their potential performances using Geant4 Monte Carlo simulations. Here, a pixel-geometry-matching collimator is defined as a collimator which is divided into the same number of pixels as the detector's and the center of each pixel in the collimator is a one-to-one correspondence to that in the detector. The detector is made of Cadmium Zinc Telluride (CZT), which is one of the most promising materials for applications to detect hard X-rays and γ -rays due to its ability to obtain good energy resolution and high light output at room temperature. For our current project, we have designed a large-area, CZT-based gamma camera (20.192 cm×20.192 cm) with a small pixel pitch (1.60 mm). The detector is pixelated and hence the intrinsic resolution can be as small as the size of the pixel. Materials of collimator, collimator hole geometry, detection efficiency, and spatial resolution of the CZT detector combined with the pixel-matching collimator were calculated and analyzed under different conditions. From the simulation studies, we found that such a camera using rectangular holes has promising imaging characteristics in terms of spatial resolution, detection efficiency, and energy resolution.

ESPRESSO: projecting a rocky exoplanet hunter for the VLT

NASA Astrophysics Data System (ADS)

Mégevand, Denis; Herreros, José-Miguel; Zerbi, Filippo; Cabral, Alexandre; Di Marcantonio, Paolo; Lovis, Christophe; Pepe, Francesco; Cristiani, Stefano; Rebolo, Rafael; Santos, Nuno C.

2010-07-01

ESPRESSO is a high-resolution, highly stable spectrograph for the VLT. It will inherit and enhance most capabilities from HARPS and UVES, combining both stability and efficiency. The main science driver will be the detection and characterization of Earth-like planets, but many additional science cases will benefit from its highly stable spectroscopic observations. The facility will be installed at the combined Coudé focus of the VLT and may be linked with any of the four UT telescopes, enabling thus a great flexibility for the efficient use of telescope time. This particularity makes the interface with the VLT more complex than for an instrument fed by a single telescope. It impacts on the complexity of the relationship between the consortium providing the instrument and ESO, the customer. The targeted high RV accuracy requires very high performances in stability and resolution, which in turn require adequate technical solutions at several levels. This paper describes the instrument system and subsystems, enlightening the most valuable differences between ESPRESSO and it's predecessors, the details of the project, entering now the design phases, the ESPRESSO consortium, composed of Italian, Portuguese, Spanish and Swiss institutes, and the relationship between the consortium and ESO.

Time‐efficient and flexible design of optimized multishell HARDI diffusion

PubMed Central

Tournier, J. Donald; Price, Anthony N.; Cordero‐Grande, Lucilio; Hughes, Emer J.; Malik, Shaihan; Steinweg, Johannes; Bastiani, Matteo; Sotiropoulos, Stamatios N.; Jbabdi, Saad; Andersson, Jesper; Edwards, A. David; Hajnal, Joseph V.

2017-01-01

Purpose Advanced diffusion magnetic resonance imaging benefits from collecting as much data as is feasible but is highly sensitive to subject motion and the risk of data loss increases with longer acquisition times. Our purpose was to create a maximally time‐efficient and flexible diffusion acquisition capability with built‐in robustness to partially acquired or interrupted scans. Our framework has been developed for the developing Human Connectome Project, but different application domains are equally possible. Methods Complete flexibility in the sampling of diffusion space combined with free choice of phase‐encode‐direction and the temporal ordering of the sampling scheme was developed taking into account motion robustness, internal consistency, and hardware limits. A split‐diffusion‐gradient preparation, multiband acceleration, and a restart capacity were added. Results The framework was used to explore different parameters choices for the desired high angular resolution diffusion imaging diffusion sampling. For the developing Human Connectome Project, a high‐angular resolution, maximally time‐efficient (20 min) multishell protocol with 300 diffusion‐weighted volumes was acquired in >400 neonates. An optimal design of a high‐resolution (1.2 × 1.2 mm2) two‐shell acquisition with 54 diffusion weighted volumes was obtained using a split‐gradient design. Conclusion The presented framework provides flexibility to generate time‐efficient and motion‐robust diffusion magnetic resonance imaging acquisitions taking into account hardware constraints that might otherwise result in sub‐optimal choices. Magn Reson Med 79:1276–1292, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:28557055

CHISL: the combined high-resolution and imaging spectrograph for the LUVOIR surveyor

NASA Astrophysics Data System (ADS)

France, Kevin; Fleming, Brian; Hoadley, Keri

2016-10-01

NASA is currently carrying out science and technical studies to identify its next astronomy flagship mission, slated to begin development in the 2020s. It has become clear that a Large Ultraviolet/Optical/IR (LUVOIR) surveyor mission (d≈12 m, Δλ≈1000 Å, 2 μm spectroscopic bandpass) can carry out the largest number of NASA's exoplanet and astrophysics science goals over the coming decades. The science grasp of an LUVOIR surveyor is broad, ranging from the direct detection of potential biomarkers on rocky planets to the flow of matter into and out of galaxies and the history of star-formation across cosmic time. There are technical challenges for several aspects of the LUVOIR surveyor concept, including component level technology readiness maturation and science instrument concepts for a broadly capable ultraviolet spectrograph. We present the scientific motivation for, and a preliminary design of, a multiplexed ultraviolet spectrograph to support both the exoplanet and astrophysics goals of the LUVOIR surveyor mission concept, the combined high-resolution and imaging spectrograph for the LUVOIR surveyor (CHISL). CHISL includes a high-resolution (R≈120,000 1000 to 1700 Å) point-source spectroscopy channel and a medium-resolution (R≥14,000 from 1000 to 2000 Å in a single observation and R˜24,000 to 35,000 in multiple grating settings) imaging spectroscopy channel. CHISL addresses topics ranging from characterizing the composition and structure of planet-forming disks to the feedback of matter between galaxies and the intergalactic medium. We present the CHISL concept, a small sample of representative science cases, and the primary technological hurdles. Technical challenges include high-efficiency ultraviolet coatings and high-quantum efficiency, large-format, photon counting detectors. We are actively engaged in laboratory and flight characterization efforts for all of these enabling technologies as components on sounding rocket payloads under development at the University of Colorado. We describe two payloads that are designed to be pathfinder instruments for the high-resolution (CHESS) and imaging spectroscopy (SISTINE) arms of CHISL. We are carrying out this instrument design, characterization, and flight-testing today to support the new start of an LUVOIR surveyor mission in the next decade.

Recent developments in software tools for high-throughput in vitro ADME support with high-resolution MS.

PubMed

Paiva, Anthony; Shou, Wilson Z

2016-08-01

The last several years have seen the rapid adoption of the high-resolution MS (HRMS) for bioanalytical support of high throughput in vitro ADME profiling. Many capable software tools have been developed and refined to process quantitative HRMS bioanalysis data for ADME samples with excellent performance. Additionally, new software applications specifically designed for quan/qual soft spot identification workflows using HRMS have greatly enhanced the quality and efficiency of the structure elucidation process for high throughput metabolite ID in early in vitro ADME profiling. Finally, novel approaches in data acquisition and compression, as well as tools for transferring, archiving and retrieving HRMS data, are being continuously refined to tackle the issue of large data file size typical for HRMS analyses.

Visible-Frequency Dielectric Metasurfaces for Multiwavelength Achromatic and Highly Dispersive Holograms.

PubMed

Wang, Bo; Dong, Fengliang; Li, Qi-Tong; Yang, Dong; Sun, Chengwei; Chen, Jianjun; Song, Zhiwei; Xu, Lihua; Chu, Weiguo; Xiao, Yun-Feng; Gong, Qihuang; Li, Yan

2016-08-10

Dielectric metasurfaces built up with nanostructures of high refractive index represent a powerful platform for highly efficient flat optical devices due to their easy-tuning electromagnetic scattering properties and relatively high transmission efficiencies. Here we show visible-frequency silicon metasurfaces formed by three kinds of nanoblocks multiplexed in a subwavelength unit to constitute a metamolecule, which are capable of wavefront manipulation for red, green, and blue light simultaneously. Full phase control is achieved for each wavelength by independently changing the in-plane orientations of the corresponding nanoblocks to induce the required geometric phases. Achromatic and highly dispersive meta-holograms are fabricated to demonstrate the wavefront manipulation with high resolution. This technique could be viable for various practical holographic applications and flat achromatic devices.

Ultrafast laser direct hard-mask writing for high efficiency c-Si texture designs

NASA Astrophysics Data System (ADS)

Kumar, Kitty; Lee, Kenneth K. C.; Nogami, Jun; Herman, Peter R.; Kherani, Nazir P.

2013-03-01

This study reports a high-resolution hard-mask laser writing technique to facilitate the selective etching of crystalline silicon (c-Si) into an inverted-pyramidal texture with feature size and periodicity on the order of the wavelength which, thus, provides for both anti-reflection and effective light-trapping of infrared and visible light. The process also enables engineered positional placement of the inverted-pyramid thereby providing another parameter for optimal design of an optically efficient pattern. The proposed technique, a non-cleanroom process, is scalable for large area micro-fabrication of high-efficiency thin c-Si photovoltaics. Optical wave simulations suggest the fabricated textured surface with 1.3 μm inverted-pyramids and a single anti-reflective coating increases the relative energy conversion efficiency by 11% compared to the PERL-cell texture with 9 μm inverted pyramids on a 400 μm thick wafer. This efficiency gain is anticipated to improve further for thinner wafers due to enhanced diffractive light trapping effects.

Flow-Signature Analysis of Water Consumption in Nonresidential Building Water Networks Using High-Resolution and Medium-Resolution Smart Meter Data: Two Case Studies

NASA Astrophysics Data System (ADS)

Clifford, Eoghan; Mulligan, Sean; Comer, Joanne; Hannon, Louise

2018-01-01

Real-time monitoring of water consumption activities can be an effective mechanism to achieve efficient water network management. This approach, largely enabled by the advent of smart metering technologies, is gradually being practiced in domestic and industrial contexts. In particular, identifying water consumption habits from flow-signatures, i.e., the specific end-usage patterns, is being investigated as a means for conservation in both the residential and nonresidential context. However, the quality of meter data is bivariate (dependent on number of meters and data temporal resolution) and as a result, planning a smart metering scheme is relatively difficult with no generic design approach available. In this study, a comprehensive medium-resolution to high-resolution smart metering program was implemented at two nonresidential trial sites to evaluate the effect of spatial and temporal data aggregation. It was found that medium-resolution water meter data were capable of exposing regular, continuous, peak use, and diurnal patterns which reflect group wide end-usage characteristics. The high-resolution meter data permitted flow-signature at a personal end-use level. Through this unique opportunity to observe water usage characteristics via flow-signature patterns, newly defined hydraulic-based design coefficients determined from Poisson rectangular pulse were developed to intuitively aid in the process of pattern discovery with implications for automated activity recognition applications. A smart meter classification and siting index was introduced which categorizes meter resolution in terms of their suitable application.

Anatomically accurate high resolution modeling of human whole heart electromechanics: A strongly scalable algebraic multigrid solver method for nonlinear deformation

NASA Astrophysics Data System (ADS)

Augustin, Christoph M.; Neic, Aurel; Liebmann, Manfred; Prassl, Anton J.; Niederer, Steven A.; Haase, Gundolf; Plank, Gernot

2016-01-01

Electromechanical (EM) models of the heart have been used successfully to study fundamental mechanisms underlying a heart beat in health and disease. However, in all modeling studies reported so far numerous simplifications were made in terms of representing biophysical details of cellular function and its heterogeneity, gross anatomy and tissue microstructure, as well as the bidirectional coupling between electrophysiology (EP) and tissue distension. One limiting factor is the employed spatial discretization methods which are not sufficiently flexible to accommodate complex geometries or resolve heterogeneities, but, even more importantly, the limited efficiency of the prevailing solver techniques which is not sufficiently scalable to deal with the incurring increase in degrees of freedom (DOF) when modeling cardiac electromechanics at high spatio-temporal resolution. This study reports on the development of a novel methodology for solving the nonlinear equation of finite elasticity using human whole organ models of cardiac electromechanics, discretized at a high para-cellular resolution. Three patient-specific, anatomically accurate, whole heart EM models were reconstructed from magnetic resonance (MR) scans at resolutions of 220 μm, 440 μm and 880 μm, yielding meshes of approximately 184.6, 24.4 and 3.7 million tetrahedral elements and 95.9, 13.2 and 2.1 million displacement DOF, respectively. The same mesh was used for discretizing the governing equations of both electrophysiology (EP) and nonlinear elasticity. A novel algebraic multigrid (AMG) preconditioner for an iterative Krylov solver was developed to deal with the resulting computational load. The AMG preconditioner was designed under the primary objective of achieving favorable strong scaling characteristics for both setup and solution runtimes, as this is key for exploiting current high performance computing hardware. Benchmark results using the 220 μm, 440 μm and 880 μm meshes demonstrate efficient scaling up to 1024, 4096 and 8192 compute cores which allowed the simulation of a single heart beat in 44.3, 87.8 and 235.3 minutes, respectively. The efficiency of the method allows fast simulation cycles without compromising anatomical or biophysical detail.

Anatomically accurate high resolution modeling of human whole heart electromechanics: A strongly scalable algebraic multigrid solver method for nonlinear deformation

PubMed Central

Augustin, Christoph M.; Neic, Aurel; Liebmann, Manfred; Prassl, Anton J.; Niederer, Steven A.; Haase, Gundolf; Plank, Gernot

2016-01-01

Electromechanical (EM) models of the heart have been used successfully to study fundamental mechanisms underlying a heart beat in health and disease. However, in all modeling studies reported so far numerous simplifications were made in terms of representing biophysical details of cellular function and its heterogeneity, gross anatomy and tissue microstructure, as well as the bidirectional coupling between electrophysiology (EP) and tissue distension. One limiting factor is the employed spatial discretization methods which are not sufficiently flexible to accommodate complex geometries or resolve heterogeneities, but, even more importantly, the limited efficiency of the prevailing solver techniques which are not sufficiently scalable to deal with the incurring increase in degrees of freedom (DOF) when modeling cardiac electromechanics at high spatio-temporal resolution. This study reports on the development of a novel methodology for solving the nonlinear equation of finite elasticity using human whole organ models of cardiac electromechanics, discretized at a high para-cellular resolution. Three patient-specific, anatomically accurate, whole heart EM models were reconstructed from magnetic resonance (MR) scans at resolutions of 220 μm, 440 μm and 880 μm, yielding meshes of approximately 184.6, 24.4 and 3.7 million tetrahedral elements and 95.9, 13.2 and 2.1 million displacement DOF, respectively. The same mesh was used for discretizing the governing equations of both electrophysiology (EP) and nonlinear elasticity. A novel algebraic multigrid (AMG) preconditioner for an iterative Krylov solver was developed to deal with the resulting computational load. The AMG preconditioner was designed under the primary objective of achieving favorable strong scaling characteristics for both setup and solution runtimes, as this is key for exploiting current high performance computing hardware. Benchmark results using the 220 μm, 440 μm and 880 μm meshes demonstrate efficient scaling up to 1024, 4096 and 8192 compute cores which allowed the simulation of a single heart beat in 44.3, 87.8 and 235.3 minutes, respectively. The efficiency of the method allows fast simulation cycles without compromising anatomical or biophysical detail. PMID:26819483

Ultrafast detection in particle physics and positron emission tomography using SiPMs

NASA Astrophysics Data System (ADS)

Dolenec, R.; Korpar, S.; Križan, P.; Pestotnik, R.

2017-12-01

Silicon photomultiplier (SiPM) photodetectors perform well in many particle and medical physics applications, especially where good efficiency, insensitivity to magnetic field and precise timing are required. In Cherenkov time-of-flight positron emission tomography the requirements for photodetector performance are especially high. On average only a couple of photons are available for detection and the best possible timing resolution is needed. Using SiPMs as photodetectors enables good detection efficiency, but the large sensitive area devices needed have somewhat limited time resolution for single photons. We have observed an additional degradation of the timing at very low light intensities due to delayed events in distribution of signals resulting from multiple fired micro cells. In this work we present the timing properties of AdvanSiD ASD-NUV3S-P-40 SiPM at single photon level picosecond laser illumination and a simple modification of the time-walk correction algorithm, that resulted in reduced degradation of timing resolution due to the delayed events.

Graphics Processing Units (GPU) and the Goddard Earth Observing System atmospheric model (GEOS-5): Implementation and Potential Applications

NASA Technical Reports Server (NTRS)

Putnam, William M.

2011-01-01

Earth system models like the Goddard Earth Observing System model (GEOS-5) have been pushing the limits of large clusters of multi-core microprocessors, producing breath-taking fidelity in resolving cloud systems at a global scale. GPU computing presents an opportunity for improving the efficiency of these leading edge models. A GPU implementation of GEOS-5 will facilitate the use of cloud-system resolving resolutions in data assimilation and weather prediction, at resolutions near 3.5 km, improving our ability to extract detailed information from high-resolution satellite observations and ultimately produce better weather and climate predictions

Superresolution SAR Imaging Algorithm Based on Mvm and Weighted Norm Extrapolation

NASA Astrophysics Data System (ADS)

Zhang, P.; Chen, Q.; Li, Z.; Tang, Z.; Liu, J.; Zhao, L.

2013-08-01

In this paper, we present an extrapolation approach, which uses minimum weighted norm constraint and minimum variance spectrum estimation, for improving synthetic aperture radar (SAR) resolution. Minimum variance method is a robust high resolution method to estimate spectrum. Based on the theory of SAR imaging, the signal model of SAR imagery is analyzed to be feasible for using data extrapolation methods to improve the resolution of SAR image. The method is used to extrapolate the efficient bandwidth in phase history field and better results are obtained compared with adaptive weighted norm extrapolation (AWNE) method and traditional imaging method using simulated data and actual measured data.

Taheri-Saramad x-ray detector (TSXD): a novel high spatial resolution x-ray imager based on ZnO nano scintillator wires in polycarbonate membrane.

PubMed

Taheri, A; Saramad, S; Ghalenoei, S; Setayeshi, S

2014-01-01

A novel x-ray imager based on ZnO nanowires is designed and fabricated. The proposed architecture is based on scintillation properties of ZnO nanostructures in a polycarbonate track-etched membrane. Because of higher refractive index of ZnO nanowire compared to the membrane, the nanowire acts as an optical fiber that prevents the generated optical photons to spread inside the detector. This effect improves the spatial resolution of the imager. The detection quantum efficiency and spatial resolution of the fabricated imager are 11% and <6.8 μm, respectively.

Polarization- and wavelength-resolved near-field imaging of complex plasmonic modes in Archimedean nanospirals

DOE PAGES

Hachtel, Jordan A.; Davidson, II, Roderick B.; Kovalik, Elena R.; ...

2018-02-15

Asymmetric nanophotonic structures enable a wide range of opportunities in optical nanotechnology because they support efficient optical nonlinearities mediated by multiple plasmon resonances over a broad spectral range. The Archimedean nanospiral is a canonical example of a chiral plasmonic structure because it supports even-order nonlinearities that are not generally accessible in locally symmetric geometries. However, the complex spiral response makes nanoscale experimental characterization of the plasmonic near-field structure highly desirable. As a result, we employ high-efficiency, high-spatial-resolution cathodoluminescence imaging in a scanning transmission electron microscope to describe the spatial, spectral, and polarization response of plasmon modes in the nanospiral geometry.

Polarization- and wavelength-resolved near-field imaging of complex plasmonic modes in Archimedean nanospirals

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

Hachtel, Jordan A.; Davidson, II, Roderick B.; Kovalik, Elena R.

Asymmetric nanophotonic structures enable a wide range of opportunities in optical nanotechnology because they support efficient optical nonlinearities mediated by multiple plasmon resonances over a broad spectral range. The Archimedean nanospiral is a canonical example of a chiral plasmonic structure because it supports even-order nonlinearities that are not generally accessible in locally symmetric geometries. However, the complex spiral response makes nanoscale experimental characterization of the plasmonic near-field structure highly desirable. As a result, we employ high-efficiency, high-spatial-resolution cathodoluminescence imaging in a scanning transmission electron microscope to describe the spatial, spectral, and polarization response of plasmon modes in the nanospiral geometry.

First high-statistics and high-resolution recoil-ion data from the WITCH retardation spectrometer

NASA Astrophysics Data System (ADS)

Finlay, P.; Breitenfeldt, M.; Porobić, T.; Wursten, E.; Ban, G.; Beck, M.; Couratin, C.; Fabian, X.; Fléchard, X.; Friedag, P.; Glück, F.; Herlert, A.; Knecht, A.; Kozlov, V. Y.; Liénard, E.; Soti, G.; Tandecki, M.; Traykov, E.; Van Gorp, S.; Weinheimer, Ch.; Zákoucký, D.; Severijns, N.

2016-07-01

The first high-statistics and high-resolution data set for the integrated recoil-ion energy spectrum following the β^+ decay of 35Ar has been collected with the WITCH retardation spectrometer located at CERN-ISOLDE. Over 25 million recoil-ion events were recorded on a large-area multichannel plate (MCP) detector with a time-stamp precision of 2ns and position resolution of 0.1mm due to the newly upgraded data acquisition based on the LPC Caen FASTER protocol. The number of recoil ions was measured for more than 15 different settings of the retardation potential, complemented by dedicated background and half-life measurements. Previously unidentified systematic effects, including an energy-dependent efficiency of the main MCP and a radiation-induced time-dependent background, have been identified and incorporated into the analysis. However, further understanding and treatment of the radiation-induced background requires additional dedicated measurements and remains the current limiting factor in extracting a beta-neutrino angular correlation coefficient for 35Ar decay using the WITCH spectrometer.

An Efficient Local Correlation Matrix Decomposition Approach for the Localization Implementation of Ensemble-Based Assimilation Methods

NASA Astrophysics Data System (ADS)

Zhang, Hongqin; Tian, Xiangjun

2018-04-01

Ensemble-based data assimilation methods often use the so-called localization scheme to improve the representation of the ensemble background error covariance (Be). Extensive research has been undertaken to reduce the computational cost of these methods by using the localized ensemble samples to localize Be by means of a direct decomposition of the local correlation matrix C. However, the computational costs of the direct decomposition of the local correlation matrix C are still extremely high due to its high dimension. In this paper, we propose an efficient local correlation matrix decomposition approach based on the concept of alternating directions. This approach is intended to avoid direct decomposition of the correlation matrix. Instead, we first decompose the correlation matrix into 1-D correlation matrices in the three coordinate directions, then construct their empirical orthogonal function decomposition at low resolution. This procedure is followed by the 1-D spline interpolation process to transform the above decompositions to the high-resolution grid. Finally, an efficient correlation matrix decomposition is achieved by computing the very similar Kronecker product. We conducted a series of comparison experiments to illustrate the validity and accuracy of the proposed local correlation matrix decomposition approach. The effectiveness of the proposed correlation matrix decomposition approach and its efficient localization implementation of the nonlinear least-squares four-dimensional variational assimilation are further demonstrated by several groups of numerical experiments based on the Advanced Research Weather Research and Forecasting model.

Resonating periodic waveguides as ultraresolution sensors in biomedicine

NASA Astrophysics Data System (ADS)

Wawro, Debra D.; Priambodo, Purnomo; Magnusson, Robert

2004-10-01

Optical sensor technology based on subwavelength periodic waveguides is applied for tag-free, high-resolution biomedical and chemical detection. Measured resonance wavelength shifts of 6.4 nm for chemically attached Bovine Serum Albumin agree well with theory for a sensor tested in air. Reflection peak efficiencies of 90% are measured, and do not degrade upon biolayer attachment. Phase detection methods are investigated to enhance sensor sensitivity and resolution. Direct measurement of the resonant phase response is reported for the first time using ellipsometric measurement techniques.

Nanosurveyor: a framework for real-time data processing

DOE PAGES

Daurer, Benedikt J.; Krishnan, Hari; Perciano, Talita; ...

2017-01-31

Background: The ever improving brightness of accelerator based sources is enabling novel observations and discoveries with faster frame rates, larger fields of view, higher resolution, and higher dimensionality. Results: Here we present an integrated software/algorithmic framework designed to capitalize on high-throughput experiments through efficient kernels, load-balanced workflows, which are scalable in design. We describe the streamlined processing pipeline of ptychography data analysis. Conclusions: The pipeline provides throughput, compression, and resolution as well as rapid feedback to the microscope operators.

Multicolor 4D Fluorescence Microscopy using Ultrathin Bessel Light Sheets

PubMed Central

Zhao, Teng; Lau, Sze Cheung; Wang, Ying; Su, Yumian; Wang, Hao; Cheng, Aifang; Herrup, Karl; Ip, Nancy Y.; Du, Shengwang; Loy, M. M. T.

2016-01-01

We demonstrate a simple and efficient method for producing ultrathin Bessel (‘non-diffracting’) light sheets of any color using a line-shaped beam and an annulus filter. With this robust and cost-effective technology, we obtained two-color, 3D images of biological samples with lateral/axial resolution of 250 nm/400 nm, and high-speed, 4D volume imaging of 20 μm sized live sample at 1 Hz temporal resolution. PMID:27189786

Impulse Response Shaping for Ultra Wide Band SAR in a Circular Flight Path

NASA Technical Reports Server (NTRS)

Jin, Michael Y.

1996-01-01

An ultra wide band SAR (synthetic aperture radar) has potential applications on imaging underground objects. Flying this SAR in a circular flight path is an efficient way to acquire high resolution images from a localized area. This paper characterizes the impulse response of sucha system. The results indicate that to achieve an image with a more uniformed resolution over the entire imaged area, proper weighting coeficients should be applied to both the principle aperture and the complimentary aperture.

Efficient L1 regularization-based reconstruction for fluorescent molecular tomography using restarted nonlinear conjugate gradient.

PubMed

Shi, Junwei; Zhang, Bin; Liu, Fei; Luo, Jianwen; Bai, Jing

2013-09-15

For the ill-posed fluorescent molecular tomography (FMT) inverse problem, the L1 regularization can protect the high-frequency information like edges while effectively reduce the image noise. However, the state-of-the-art L1 regularization-based algorithms for FMT reconstruction are expensive in memory, especially for large-scale problems. An efficient L1 regularization-based reconstruction algorithm based on nonlinear conjugate gradient with restarted strategy is proposed to increase the computational speed with low memory consumption. The reconstruction results from phantom experiments demonstrate that the proposed algorithm can obtain high spatial resolution and high signal-to-noise ratio, as well as high localization accuracy for fluorescence targets.

Compact CdZnTe-based gamma camera for prostate cancer imaging

NASA Astrophysics Data System (ADS)

Cui, Yonggang; Lall, Terry; Tsui, Benjamin; Yu, Jianhua; Mahler, George; Bolotnikov, Aleksey; Vaska, Paul; De Geronimo, Gianluigi; O'Connor, Paul; Meinken, George; Joyal, John; Barrett, John; Camarda, Giuseppe; Hossain, Anwar; Kim, Ki Hyun; Yang, Ge; Pomper, Marty; Cho, Steve; Weisman, Ken; Seo, Youngho; Babich, John; LaFrance, Norman; James, Ralph B.

2011-06-01

In this paper, we discuss the design of a compact gamma camera for high-resolution prostate cancer imaging using Cadmium Zinc Telluride (CdZnTe or CZT) radiation detectors. Prostate cancer is a common disease in men. Nowadays, a blood test measuring the level of prostate specific antigen (PSA) is widely used for screening for the disease in males over 50, followed by (ultrasound) imaging-guided biopsy. However, PSA tests have a high falsepositive rate and ultrasound-guided biopsy has a high likelihood of missing small cancerous tissues. Commercial methods of nuclear medical imaging, e.g. PET and SPECT, can functionally image the organs, and potentially find cancer tissues at early stages, but their applications in diagnosing prostate cancer has been limited by the smallness of the prostate gland and the long working distance between the organ and the detectors comprising these imaging systems. CZT is a semiconductor material with wide band-gap and relatively high electron mobility, and thus can operate at room temperature without additional cooling. CZT detectors are photon-electron direct-conversion devices, thus offering high energy-resolution in detecting gamma rays, enabling energy-resolved imaging, and reducing the background of Compton-scattering events. In addition, CZT material has high stopping power for gamma rays; for medical imaging, a few-mm-thick CZT material provides adequate detection efficiency for many SPECT radiotracers. Because of these advantages, CZT detectors are becoming popular for several SPECT medical-imaging applications. Most recently, we designed a compact gamma camera using CZT detectors coupled to an application-specific-integratedcircuit (ASIC). This camera functions as a trans-rectal probe to image the prostate gland from a distance of only 1-5 cm, thus offering higher detection efficiency and higher spatial resolution. Hence, it potentially can detect prostate cancers at their early stages. The performance tests of this camera have been completed. The results show better than 6-mm resolution at a distance of 1 cm. Details of the test results are discussed in this paper.

Development of silicon grisms and immersion gratings for high-resolution infrared spectroscopy

NASA Astrophysics Data System (ADS)

Ge, Jian; McDavitt, Daniel L.; Bernecker, John L.; Miller, Shane; Ciarlo, Dino R.; Kuzmenko, Paul J.

2002-01-01

We report new results on silicon grism and immersion grating development using photolithography and anisotropic chemical etching techniques, which include process recipe finding, prototype grism fabrication, lab performance evaluation and initial scientific observations. The very high refractive index of silicon (n=3.4) enables much higher dispersion power for silicon-based gratings than conventional gratings, e.g. a silicon immersion grating can offer a factor of 3.4 times the dispersion of a conventional immersion grating. Good transmission in the infrared (IR) allows silicon-based gratings to operate in the broad IR wavelength regions (~1- 10 micrometers and far-IR), which make them attractive for both ground and space-based spectroscopic observations. Coarser gratings can be fabricated with these new techniques rather than conventional techniques, allowing observations at very high dispersion orders for larger simultaneous wavelength coverage. We have found new etching techniques for fabricating high quality silicon grisms with low wavefront distortion, low scattered light and high efficiency. Particularly, a new etching process using tetramethyl ammonium hydroxide (TMAH) is significantly simplifying the fabrication process on large, thick silicon substrates, while providing comparable grating quality to our traditional potassium hydroxide (KOH) process. This technique is being used for fabricating inch size silicon grisms for several IR instruments and is planned to be used for fabricating ~ 4 inch size silicon immersion gratings later. We have obtained complete K band spectra of a total of 6 T Tauri and Ae/Be stars and their close companions at a spectral resolution of R ~ 5000 using a silicon echelle grism with a 5 mm pupil diameter at the Lick 3m telescope. These results represent the first scientific observations conducted by the high-resolution silicon grisms, and demonstrate the extremely high dispersing power of silicon- based gratings. The future of silicon-based grating applications in ground and space-based IR instruments is promising. Silicon immersion gratings will make very high-resolution spectroscopy (R>100,000) feasible with compact instruments for implementation on large telescopes. Silicon grisms will offer an efficient way to implement low-cost medium to high resolution IR spectroscopy (R~ 1000-50000) through the conversion of existing cameras into spectrometers by locating a grism in the instrument's pupil location.

Low-resolution ship detection from high-altitude aerial images

NASA Astrophysics Data System (ADS)

Qi, Shengxiang; Wu, Jianmin; Zhou, Qing; Kang, Minyang

2018-02-01

Ship detection from optical images taken by high-altitude aircrafts such as unmanned long-endurance airships and unmanned aerial vehicles has broad applications in marine fishery management, ship monitoring and vessel salvage. However, the major challenge is the limited capability of information processing on unmanned high-altitude platforms. Furthermore, in order to guarantee the wide detection range, unmanned aircrafts generally cruise at high altitudes, resulting in imagery with low-resolution targets and strong clutters suffered by heavy clouds. In this paper, we propose a low-resolution ship detection method to extract ships from these high-altitude optical images. Inspired by a recent research on visual saliency detection indicating that small salient signals could be well detected by a gradient enhancement operation combined with Gaussian smoothing, we propose the facet kernel filtering to rapidly suppress cluttered backgrounds and delineate candidate target regions from the sea surface. Then, the principal component analysis (PCA) is used to compute the orientation of the target axis, followed by a simplified histogram of oriented gradient (HOG) descriptor to characterize the ship shape property. Finally, support vector machine (SVM) is applied to discriminate real targets and false alarms. Experimental results show that the proposed method actually has high efficiency in low-resolution ship detection.

Highly efficient chiral resolution of DL-arginine by cocrystal formation followed by recrystallization under preferential-enrichment conditions.

PubMed

Iwama, Sekai; Kuyama, Kazunori; Mori, Yuko; Manoj, Kochunnoonny; Gonnade, Rajesh G; Suzuki, Katsuaki; Hughes, Colan E; Williams, P Andrew; Harris, Kenneth D M; Veesler, Stéphane; Takahashi, Hiroki; Tsue, Hirohito; Tamura, Rui

2014-08-11

An excellent chiral symmetry-breaking spontaneous enantiomeric resolution phenomenon, denoted preferential enrichment, was observed on recrystallization of the 1:1 cocrystal of dl-arginine and fumaric acid, which is classified as a racemic compound crystal with a high eutectic ee value (>95 %), under non-equilibrium crystallization conditions. On the basis of temperature-controlled video microscopy and in situ time-resolved solid-state (13) C NMR spectroscopic studies on the crystallization process, a new mechanism of phase transition that can induce preferential enrichment is proposed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthetic aperture radar target detection, feature extraction, and image formation techniques

NASA Technical Reports Server (NTRS)

Li, Jian

1994-01-01

This report presents new algorithms for target detection, feature extraction, and image formation with the synthetic aperture radar (SAR) technology. For target detection, we consider target detection with SAR and coherent subtraction. We also study how the image false alarm rates are related to the target template false alarm rates when target templates are used for target detection. For feature extraction from SAR images, we present a computationally efficient eigenstructure-based 2D-MODE algorithm for two-dimensional frequency estimation. For SAR image formation, we present a robust parametric data model for estimating high resolution range signatures of radar targets and for forming high resolution SAR images.

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.

An ROI multi-resolution compression method for 3D-HEVC

NASA Astrophysics Data System (ADS)

Ti, Chunli; Guan, Yudong; Xu, Guodong; Teng, Yidan; Miao, Xinyuan

2017-09-01

3D High Efficiency Video Coding (3D-HEVC) provides a significant potential on increasing the compression ratio of multi-view RGB-D videos. However, the bit rate still rises dramatically with the improvement of the video resolution, which will bring challenges to the transmission network, especially the mobile network. This paper propose an ROI multi-resolution compression method for 3D-HEVC to better preserve the information in ROI on condition of limited bandwidth. This is realized primarily through ROI extraction and compression multi-resolution preprocessed video as alternative data according to the network conditions. At first, the semantic contours are detected by the modified structured forests to restrain the color textures inside objects. The ROI is then determined utilizing the contour neighborhood along with the face region and foreground area of the scene. Secondly, the RGB-D videos are divided into slices and compressed via 3D-HEVC under different resolutions for selection by the audiences and applications. Afterwards, the reconstructed low-resolution videos from 3D-HEVC encoder are directly up-sampled via Laplace transformation and used to replace the non-ROI areas of the high-resolution videos. Finally, the ROI multi-resolution compressed slices are obtained by compressing the ROI preprocessed videos with 3D-HEVC. The temporal and special details of non-ROI are reduced in the low-resolution videos, so the ROI will be better preserved by the encoder automatically. Experiments indicate that the proposed method can keep the key high-frequency information with subjective significance while the bit rate is reduced.

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

Stuckelberger, Michael; Nietzold, Tara; Hall, Genevieve N.

Unveiling the correlation between elemental composition, Fermi-level splitting, and charge collection in perovskite solar cells (PSCs) when exposed to different environments is crucial to understanding the origin of defects. This will enable defect engineering to achieve high-performance and long-lasting PSCs. Here, in this paper, we measured, for the first time, the spatial distribution and charge-collection efficiency at the nanoscale by synchrotron-based X-ray fluorescence (XRF) and X-ray beam-induced current (XBIC) with subgrain resolution, and we observe a correlation between Pb/I ratio and charge-collection efficiency. In contrast with other thin-film solar cells, PSCs are highly sensitive to ambient conditions (atmosphere and illumination).more » As the XRF and XBIC measurements were conducted in vacuum under an X-ray source illumination, the impact of measurement conditions on the cells needs to be taken into account. Furthermore, necessary conditions for quantification of XRF/XBIC measurements, such as film homogeneity, are not fulfilled in the case of PSCs. Finally, we will discuss fundamentals of XRF/XBIC measurements of PSCs that will enable reliable, quantitative, high-resolution measurements of elemental distribution and charge collection.« less

A high-resolution and intelligent dead pixel detection scheme for an electrowetting display screen

NASA Astrophysics Data System (ADS)

Luo, ZhiJie; Luo, JianKun; Zhao, WenWen; Cao, Yang; Lin, WeiJie; Zhou, GuoFu

2018-02-01

Electrowetting display technology is realized by tuning the surface energy of a hydrophobic surface by applying a voltage based on electrowetting mechanism. With the rapid development of the electrowetting industry, how to analyze efficiently the quality of an electrowetting display screen has a very important significance. There are two kinds of dead pixels on the electrowetting display screen. One is that the oil of pixel cannot completely cover the display area. The other is that indium tin oxide semiconductor wire connecting pixel and foil was burned. In this paper, we propose a high-resolution and intelligent dead pixel detection scheme for an electrowetting display screen. First, we built an aperture ratio-capacitance model based on the electrical characteristics of electrowetting display. A field-programmable gate array is used as the integrated logic hub of the system for a highly reliable and efficient control of the circuit. Dead pixels can be detected and displayed on a PC-based 2D graphical interface in real time. The proposed dead pixel detection scheme reported in this work has promise in automating electrowetting display experiments.

Low-count PET image restoration using sparse representation

NASA Astrophysics Data System (ADS)

Li, Tao; Jiang, Changhui; Gao, Juan; Yang, Yongfeng; Liang, Dong; Liu, Xin; Zheng, Hairong; Hu, Zhanli

2018-04-01

In the field of positron emission tomography (PET), reconstructed images are often blurry and contain noise. These problems are primarily caused by the low resolution of projection data. Solving this problem by improving hardware is an expensive solution, and therefore, we attempted to develop a solution based on optimizing several related algorithms in both the reconstruction and image post-processing domains. As sparse technology is widely used, sparse prediction is increasingly applied to solve this problem. In this paper, we propose a new sparse method to process low-resolution PET images. Two dictionaries (D1 for low-resolution PET images and D2 for high-resolution PET images) are learned from a group real PET image data sets. Among these two dictionaries, D1 is used to obtain a sparse representation for each patch of the input PET image. Then, a high-resolution PET image is generated from this sparse representation using D2. Experimental results indicate that the proposed method exhibits a stable and superior ability to enhance image resolution and recover image details. Quantitatively, this method achieves better performance than traditional methods. This proposed strategy is a new and efficient approach for improving the quality of PET images.

Mercuric iodide room-temperature array detectors for gamma-ray imaging

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

Patt, B.

Significant progress has been made recently in the development of mercuric iodide detector arrays for gamma-ray imaging, making real the possibility of constructing high-performance small, light-weight, portable gamma-ray imaging systems. New techniques have been applied in detector fabrication and then low noise electronics which have produced pixel arrays with high-energy resolution, high spatial resolution, high gamma stopping efficiency. Measurements of the energy resolution capability have been made on a 19-element protypical array. Pixel energy resolutions of 2.98% fwhm and 3.88% fwhm were obtained at 59 keV (241-Am) and 140-keV (99m-Tc), respectively. The pixel spectra for a 14-element section of themore » data is shown together with the composition of the overlapped individual pixel spectra. These techniques are now being applied to fabricate much larger arrays with thousands of pixels. Extension of these principles to imaging scenarios involving gamma-ray energies up to several hundred keV is also possible. This would enable imaging of the 208 keV and 375-414 keV 239-Pu and 240-Pu structures, as well as the 186 keV line of 235-U.« less

BTDI detector technology for reconnaissance application

NASA Astrophysics Data System (ADS)

Hilbert, Stefan; Eckardt, Andreas; Krutz, David

2017-11-01

The Institute of Optical Sensor Systems (OS) at the Robotics and Mechatronics Center of the German Aerospace Center (DLR) has more than 30 years of experience with high-resolution imaging technology. This paper shows the institute's scientific results of the leading-edge detector design in a BTDI (Bidirectional Time Delay and Integration) architecture. This project demonstrates an approved technological design for high or multi-spectral resolution spaceborne instruments. DLR OS and BAE Systems were driving the technology of new detectors and the FPA design for future projects, new manufacturing accuracy in order to keep pace with ambitious scientific and user requirements. Resulting from customer requirements and available technologies the current generation of space borne sensor systems is focusing on VIS/NIR high spectral resolution to meet the requirements on earth and planetary observation systems. The combination of large swath and high-spectral resolution with intelligent control applications and new focal plane concepts opens the door to new remote sensing and smart deep space instruments. The paper gives an overview of the detector development and verification program at DLR on detector module level and key parameters like SNR, linearity, spectral response, quantum efficiency, PRNU, DSNU and MTF.

Automated Segmentation of High-Resolution Photospheric Images of Active Regions

NASA Astrophysics Data System (ADS)

Yang, Meng; Tian, Yu; Rao, Changhui

2018-02-01

Due to the development of ground-based, large-aperture solar telescopes with adaptive optics (AO) resulting in increasing resolving ability, more accurate sunspot identifications and characterizations are required. In this article, we have developed a set of automated segmentation methods for high-resolution solar photospheric images. Firstly, a local-intensity-clustering level-set method is applied to roughly separate solar granulation and sunspots. Then reinitialization-free level-set evolution is adopted to adjust the boundaries of the photospheric patch; an adaptive intensity threshold is used to discriminate between umbra and penumbra; light bridges are selected according to their regional properties from candidates produced by morphological operations. The proposed method is applied to the solar high-resolution TiO 705.7-nm images taken by the 151-element AO system and Ground-Layer Adaptive Optics prototype system at the 1-m New Vacuum Solar Telescope of the Yunnan Observatory. Experimental results show that the method achieves satisfactory robustness and efficiency with low computational cost on high-resolution images. The method could also be applied to full-disk images, and the calculated sunspot areas correlate well with the data given by the National Oceanic and Atmospheric Administration (NOAA).

Detection of grapes in natural environment using HOG features in low resolution images

NASA Astrophysics Data System (ADS)

Škrabánek, Pavel; Majerík, Filip

2017-07-01

Detection of grapes in real-life images has importance in various viticulture applications. A grape detector based on an SVM classifier, in combination with a HOG descriptor, has proven to be very efficient in detection of white varieties in high-resolution images. Nevertheless, the high time complexity of such utilization was not suitable for its real-time applications, even when a detector of a simplified structure was used. Thus, we examined possibilities of the simplified version application on images of lower resolutions. For this purpose, we designed a method aimed at search for a detector’s setting which gives the best time complexity vs. performance ratio. In order to provide precise evaluation results, we formed new extended datasets. We discovered that even applied on low-resolution images, the simplified detector, with an appropriate setting of all tuneable parameters, was competitive with other state of the art solutions. We concluded that the detector is qualified for real-time detection of grapes in real-life images.

Super-resolution imaging of multiple cells by optimized flat-field epi-illumination

NASA Astrophysics Data System (ADS)

Douglass, Kyle M.; Sieben, Christian; Archetti, Anna; Lambert, Ambroise; Manley, Suliana

2016-11-01

Biological processes are inherently multi-scale, and supramolecular complexes at the nanoscale determine changes at the cellular scale and beyond. Single-molecule localization microscopy (SMLM) techniques have been established as important tools for studying cellular features with resolutions of the order of around 10 nm. However, in their current form these modalities are limited by a highly constrained field of view (FOV) and field-dependent image resolution. Here, we develop a low-cost microlens array (MLA)-based epi-illumination system—flat illumination for field-independent imaging (FIFI)—that can efficiently and homogeneously perform simultaneous imaging of multiple cells with nanoscale resolution. The optical principle of FIFI, which is an extension of the Köhler integrator, is further elucidated and modelled with a new, free simulation package. We demonstrate FIFI's capabilities by imaging multiple COS-7 and bacteria cells in 100 × 100 μm2 SMLM images—more than quadrupling the size of a typical FOV and producing near-gigapixel-sized images of uniformly high quality.

Efficient kinetic resolution of secondary alcohols using an organic solvent-tolerant esterase in non-aqueous medium.

PubMed

Gao, Wenyuan; Fan, Haiyang; Chen, Lifeng; Wang, Hualei; Wei, Dongzhi

2016-07-01

To identify an esterase-mediated kinetic resolution of secondary alcohols in non-aqueous medium. An esterase, EST4, from a marine mud metagenomic library, showed high activity and enantioselectivity for the kinetic resolution of secondary alcohols in non-aqueous medium. Using 1-phenylethanol as the model alcohol, the effects of organic solvents, acyl donors, molar ratio, temperatures and biocatalyst loading on the kinetic resolution catalyzed by the EST4 whole-cell biocatalyst were investigated and optimized. The optimized methodology was effective on resolving 16 various racemic secondary alcohols in neat n-hexane, providing excellent enantiomeric excess (up to 99.9 % ee). Moreover, EST4 exhibited a strong tolerance for high substrate concentration (up to 1 M), and the optical purity of the desired secondary alcohols was kept above 99 % ee. The esterase EST4 is a promising biocatalyst for the enantioselective synthesis of various alcohols and esters with interesting practical applications.

Compressive light field imaging

NASA Astrophysics Data System (ADS)

Ashok, Amit; Neifeld, Mark A.

2010-04-01

Light field imagers such as the plenoptic and the integral imagers inherently measure projections of the four dimensional (4D) light field scalar function onto a two dimensional sensor and therefore, suffer from a spatial vs. angular resolution trade-off. Programmable light field imagers, proposed recently, overcome this spatioangular resolution trade-off and allow high-resolution capture of the (4D) light field function with multiple measurements at the cost of a longer exposure time. However, these light field imagers do not exploit the spatio-angular correlations inherent in the light fields of natural scenes and thus result in photon-inefficient measurements. Here, we describe two architectures for compressive light field imaging that require relatively few photon-efficient measurements to obtain a high-resolution estimate of the light field while reducing the overall exposure time. Our simulation study shows that, compressive light field imagers using the principal component (PC) measurement basis require four times fewer measurements and three times shorter exposure time compared to a conventional light field imager in order to achieve an equivalent light field reconstruction quality.

PP-SWAT: A phython-based computing software for efficient multiobjective callibration of SWAT

USDA-ARS?s Scientific Manuscript database

With enhanced data availability, distributed watershed models for large areas with high spatial and temporal resolution are increasingly used to understand water budgets and examine effects of human activities and climate change/variability on water resources. Developing parallel computing software...

Structure of the vacuolar H+-ATPase rotary motor reveals new mechanistic insights.

PubMed

Rawson, Shaun; Phillips, Clair; Huss, Markus; Tiburcy, Felix; Wieczorek, Helmut; Trinick, John; Harrison, Michael A; Muench, Stephen P

2015-03-03

Vacuolar H(+)-ATPases are multisubunit complexes that operate with rotary mechanics and are essential for membrane proton transport throughout eukaryotes. Here we report a ∼ 1 nm resolution reconstruction of a V-ATPase in a different conformational state from that previously reported for a lower-resolution yeast model. The stator network of the V-ATPase (and by implication that of other rotary ATPases) does not change conformation in different catalytic states, and hence must be relatively rigid. We also demonstrate that a conserved bearing in the catalytic domain is electrostatic, contributing to the extraordinarily high efficiency of rotary ATPases. Analysis of the rotor axle/membrane pump interface suggests how rotary ATPases accommodate different c ring stoichiometries while maintaining high efficiency. The model provides evidence for a half channel in the proton pump, supporting theoretical models of ion translocation. Our refined model therefore provides new insights into the structure and mechanics of the V-ATPases. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

FPGA-based photon-counting phase-modulation fluorometer and a brief comparison with that operated in a pulsed-excitation mode

NASA Astrophysics Data System (ADS)

Iwata, Tetsuo; Taga, Takanori; Mizuno, Takahiko

2018-02-01

We have constructed a high-efficiency, photon-counting phase-modulation fluorometer (PC-PMF) using a field-programmable gate array, which is a modified version of the photon-counting fluorometer (PCF) that works in a pulsed-excitation mode (Iwata and Mizuno in Meas Sci Technol 28:075501, 2017). The common working principle for both is the simultaneous detection of the photoelectron pulse train, which covers 64 ns with a 1.0-ns resolution time (1.0 ns/channel). The signal-gathering efficiency was improved more than 100 times over that of conventional time-correlated single-photon-counting at the expense of resolution time depending on the number of channels. The system dead time for building a histogram was eliminated, markedly shortening the measurement time for fluorescent samples with moderately high quantum yields. We describe the PC-PMF and make a brief comparison with the pulsed-excitation PCF in precision, demonstrating the potential advantage of PC-PMF.

Surface and interfacial engineering of iron oxide nanoplates for highly efficient magnetic resonance angiography.

PubMed

Zhou, Zijian; Wu, Changqiang; Liu, Hanyu; Zhu, Xianglong; Zhao, Zhenghuan; Wang, Lirong; Xu, Ye; Ai, Hua; Gao, Jinhao

2015-03-24

Magnetic resonance angiography using gadolinium-based molecular contrast agents suffers from short diagnostic window, relatively low resolution and risk of toxicity. Taking into account the chemical exchange between metal centers and surrounding protons, magnetic nanoparticles with suitable surface and interfacial features may serve as alternative T1 contrast agents. Herein, we report the engineering on surface structure of iron oxide nanoplates to boost T1 contrast ability through synergistic effects between exposed metal-rich Fe3O4(100) facets and embedded Gd2O3 clusters. The nanoplates show prominent T1 contrast in a wide range of magnetic fields with an ultrahigh r1 value up to 61.5 mM(-1) s(-1). Moreover, engineering on nanobio interface through zwitterionic molecules adjusts the in vivo behaviors of nanoplates for highly efficient magnetic resonance angiography with steady-state acquisition window, superhigh resolution in vascular details, and low toxicity. This study provides a powerful tool for sophisticated design of MRI contrast agents for diverse use in bioimaging applications.

Performance study of the neutron-TPC

NASA Astrophysics Data System (ADS)

Huang, Meng; Li, Yulan; Niu, Libo; Deng, Zhi; Cheng, Xiaolei; He, Li; Zhang, Hongyan; Fu, Jianqiang; Yan, Yangyang; Cai, Yiming; Li, Yuanjing

2017-02-01

Fast neutron spectrometers will play an important role in the future of the nuclear industry and nuclear physics experiments, in tasks such as fast neutron reactor monitoring, thermo-nuclear fusion plasma diagnostics, nuclear reaction cross-section measurement, and special nuclear material detection. Recently, a new fast neutron spectrometer based on a GEM (Gas Electron Multiplier amplification)-TPC (Time Projection Chamber), named the neutron-TPC, has been under development at Tsinghua University. It is designed to have a high energy resolution, high detection efficiency, easy access to the medium material, an outstanding n/γ suppression ratio, and a wide range of applications. This paper presents the design, test, and experimental study of the neutron-TPC. Based on the experimental results, the energy resolution (FWHM) of the neutron-TPC can reach 15.7%, 10.3% and 7.0% with detection efficiency higher than 10-5 for 1.2 MeV, 1.81 MeV and 2.5 MeV neutrons respectively. Supported by National Natural Science Foundation of China (11275109)

A High Order Finite Difference Scheme with Sharp Shock Resolution for the Euler Equations

NASA Technical Reports Server (NTRS)

Gerritsen, Margot; Olsson, Pelle

1996-01-01

We derive a high-order finite difference scheme for the Euler equations that satisfies a semi-discrete energy estimate, and present an efficient strategy for the treatment of discontinuities that leads to sharp shock resolution. The formulation of the semi-discrete energy estimate is based on a symmetrization of the Euler equations that preserves the homogeneity of the flux vector, a canonical splitting of the flux derivative vector, and the use of difference operators that satisfy a discrete analogue to the integration by parts procedure used in the continuous energy estimate. Around discontinuities or sharp gradients, refined grids are created on which the discrete equations are solved after adding a newly constructed artificial viscosity. The positioning of the sub-grids and computation of the viscosity are aided by a detection algorithm which is based on a multi-scale wavelet analysis of the pressure grid function. The wavelet theory provides easy to implement mathematical criteria to detect discontinuities, sharp gradients and spurious oscillations quickly and efficiently.

Planetary-scale surface water detection from space

NASA Astrophysics Data System (ADS)

Donchyts, G.; Baart, F.; Winsemius, H.; Gorelick, N.

2017-12-01

Accurate, efficient and high-resolution methods of surface water detection are needed for a better water management. Datasets on surface water extent and dynamics are crucial for a better understanding of natural and human-made processes, and as an input data for hydrological and hydraulic models. In spite of considerable progress in the harmonization of freely available satellite data, producing accurate and efficient higher-level surface water data products remains very challenging. This presentation will provide an overview of existing methods for surface water extent and change detection from multitemporal and multi-sensor satellite imagery. An algorithm to detect surface water changes from multi-temporal satellite imagery will be demonstrated as well as its open-source implementation (http://aqua-monitor.deltares.nl). This algorithm was used to estimate global surface water changes at high spatial resolution. These changes include climate change, land reclamation, reservoir construction/decommissioning, erosion/accretion, and many other. This presentation will demonstrate how open satellite data and open platforms such as Google Earth Engine have helped with this research.

Land cover mapping and change detection in urban watersheds using QuickBird high spatial resolution satellite imagery

NASA Astrophysics Data System (ADS)

Hester, David Barry

The objective of this research was to develop methods for urban land cover analysis using QuickBird high spatial resolution satellite imagery. Such imagery has emerged as a rich commercially available remote sensing data source and has enjoyed high-profile broadcast news media and Internet applications, but methods of quantitative analysis have not been thoroughly explored. The research described here consists of three studies focused on the use of pan-sharpened 61-cm spatial resolution QuickBird imagery, the spatial resolution of which is the highest of any commercial satellite. In the first study, a per-pixel land cover classification method is developed for use with this imagery. This method utilizes a per-pixel classification approach to generate an accurate six-category high spatial resolution land cover map of a developing suburban area. The primary objective of the second study was to develop an accurate land cover change detection method for use with QuickBird land cover products. This work presents an efficient fuzzy framework for transforming map uncertainty into accurate and meaningful high spatial resolution land cover change analysis. The third study described here is an urban planning application of the high spatial resolution QuickBird-based land cover product developed in the first study. This work both meaningfully connects this exciting new data source to urban watershed management and makes an important empirical contribution to the study of suburban watersheds. Its analysis of residential roads and driveways as well as retail parking lots sheds valuable light on the impact of transportation-related land use on the suburban landscape. Broadly, these studies provide new methods for using state-of-the-art remote sensing data to inform land cover analysis and urban planning. These methods are widely adaptable and produce land cover products that are both meaningful and accurate. As additional high spatial resolution satellites are launched and the cost of high resolution imagery continues to decline, this research makes an important contribution to this exciting era in the science of remote sensing.

The infrared imaging spectrograph (IRIS) for TMT: volume phase holographic grating performance testing and discussion

NASA Astrophysics Data System (ADS)

Chen, Shaojie; Meyer, Elliot; Wright, Shelley A.; Moore, Anna M.; Larkin, James E.; Maire, Jerome; Mieda, Etsuko; Simard, Luc

2014-07-01

Maximizing the grating efficiency is a key goal for the first light instrument IRIS (Infrared Imaging Spectrograph) currently being designed to sample the diffraction limit of the TMT (Thirty Meter Telescope). Volume Phase Holographic (VPH) gratings have been shown to offer extremely high efficiencies that approach 100% for high line frequencies (i.e., 600 to 6000l/mm), which has been applicable for astronomical optical spectrographs. However, VPH gratings have been less exploited in the near-infrared, particularly for gratings that have lower line frequencies. Given their potential to offer high throughputs and low scattered light, VPH gratings are being explored for IRIS as a potential dispersing element in the spectrograph. Our team has procured near-infrared gratings from two separate vendors. We have two gratings with the specifications needed for IRIS current design: 1.51-1.82μm (H-band) to produce a spectral resolution of 4000 and 1.19-1.37μm (J-band) to produce a spectral resolution of 8000. The center wavelengths for each grating are 1.629μm and 1.27μm, and the groove densities are 177l/mm and 440l/mm for H-band R=4000 and J-band R=8000, respectively. We directly measure the efficiencies in the lab and find that the peak efficiencies of these two types of gratings are quite good with a peak efficiency of ~88% at the Bragg angle in both TM and TE modes at H-band, and 90.23% in TM mode, 79.91% in TE mode at J-band for the best vendor. We determine the drop in efficiency off the Bragg angle, with a 20-23% decrease in efficiency at H-band when 2.5° deviation from the Bragg angle, and 25%-28% decrease at J-band when 5° deviation from the Bragg angle.

Epi-Fluorescence Microscopy

PubMed Central

Webb, Donna J.; Brown, Claire M.

2012-01-01

Epi-fluorescence microscopy is available in most life sciences research laboratories, and when optimized can be a central laboratory tool. In this chapter, the epi-fluorescence light path is introduced and the various components are discussed in detail. Recommendations are made for incident lamp light sources, excitation and emission filters, dichroic mirrors, objective lenses, and charge-coupled device (CCD) cameras in order to obtain the most sensitive epi-fluorescence microscope. The even illumination of metal-halide lamps combined with new “hard” coated filters and mirrors, a high resolution monochrome CCD camera, and a high NA objective lens are all recommended for high resolution and high sensitivity fluorescence imaging. Recommendations are also made for multicolor imaging with the use of monochrome cameras, motorized filter turrets, individual filter cubes, and corresponding dyes that are the best choice for sensitive, high resolution multicolor imaging. Images should be collected using Nyquist sampling and should be corrected for background intensity contributions and nonuniform illumination across the field of view. Photostable fluorescent probes and proteins that absorb a lot of light (i.e., high extinction co-efficients) and generate a lot of fluorescence signal (i.e., high quantum yields) are optimal. A neuronal immune-fluorescence labeling protocol is also presented. Finally, in order to maximize the utility of sensitive wide-field microscopes and generate the highest resolution images with high signal-to-noise, advice for combining wide-field epi-fluorescence imaging with restorative image deconvolution is presented. PMID:23026996

Cluster secondary ion mass spectrometry microscope mode mass spectrometry imaging.

PubMed

Kiss, András; Smith, Donald F; Jungmann, Julia H; Heeren, Ron M A

2013-12-30

Microscope mode imaging for secondary ion mass spectrometry is a technique with the promise of simultaneous high spatial resolution and high-speed imaging of biomolecules from complex surfaces. Technological developments such as new position-sensitive detectors, in combination with polyatomic primary ion sources, are required to exploit the full potential of microscope mode mass spectrometry imaging, i.e. to efficiently push the limits of ultra-high spatial resolution, sample throughput and sensitivity. In this work, a C60 primary source was combined with a commercial mass microscope for microscope mode secondary ion mass spectrometry imaging. The detector setup is a pixelated detector from the Medipix/Timepix family with high-voltage post-acceleration capabilities. The system's mass spectral and imaging performance is tested with various benchmark samples and thin tissue sections. The high secondary ion yield (with respect to 'traditional' monatomic primary ion sources) of the C60 primary ion source and the increased sensitivity of the high voltage detector setup improve microscope mode secondary ion mass spectrometry imaging. The analysis time and the signal-to-noise ratio are improved compared with other microscope mode imaging systems, all at high spatial resolution. We have demonstrated the unique capabilities of a C60 ion microscope with a Timepix detector for high spatial resolution microscope mode secondary ion mass spectrometry imaging. Copyright © 2013 John Wiley & Sons, Ltd.

An efficient way of layout processing based on calibre DRC and pattern matching for defects inspection application

NASA Astrophysics Data System (ADS)

Li, Helen; Lee, Robben; Lee, Tyzy; Xue, Teddy; Liu, Hermes; Wu, Hall; Wan, Qijian; Du, Chunshan; Hu, Xinyi; Liu, Zhengfang

2018-03-01

As technology advances, escalating layout design complexity and chip size make defect inspection becomes more challenging than ever before. The YE (Yield Enhancement) engineers are seeking for an efficient strategy to ensure accuracy without suffering running time. A smart way is to set different resolutions for different pattern structures, for examples, logic pattern areas have a higher scan resolution while the dummy areas have a lower resolution, SRAM area may have another different resolution. This can significantly reduce the scan processing time meanwhile the accuracy does not suffer. Due to the limitation of the inspection equipment, the layout must be processed in order to output the Care Area marker in line with the requirement of the equipment, for instance, the marker shapes must be rectangle and the number of the rectangle shapes should be as small as possible. The challenge is how to select the different Care Areas by pattern structures, merge the areas efficiently and then partition them into pieces of rectangle shapes. This paper presents a solution based on Calibre DRC and Pattern Matching. Calibre equation-based DRC is a powerful layout processing engine and Calibre Pattern Matching's automated visual capture capability enables designers to define these geometries as layout patterns and store them in libraries which can be re-used in multiple design layouts. Pattern Matching simplifies the description of very complex relationships between pattern shapes efficiently and accurately. Pattern matching's true power is on display when it is integrated with normal DRC deck. In this application of defects inspection, we first run Calibre DRC to get rule based Care Area then use Calibre Pattern Matching's automated pattern capture capability to capture Care Area shapes which need a higher scan resolution with a tune able pattern halo. In the pattern matching step, when the patterns are matched, a bounding box marker will be output to identify the high resolution area. The equation-based DRC and Pattern Matching effectively work together for different scan phases.

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

Sakaguchi, Koichi; Leung, Lai-Yung R.; Zhao, Chun

This study presents a diagnosis of a multi-resolution approach using the Model for Prediction Across Scales - Atmosphere (MPAS-A) for simulating regional climate. Four AMIP experiments are conducted for 1999-2009. In the first two experiments, MPAS-A is configured using global quasi-uniform grids at 120 km and 30 km grid spacing. In the other two experiments, MPAS-A is configured using variable-resolution (VR) mesh with local refinement at 30 km over North America and South America embedded inside a quasi-uniform domain at 120 km elsewhere. Precipitation and related fields in the four simulations are examined to determine how well the VR simulationsmore » reproduce the features simulated by the globally high-resolution model in the refined domain. In previous analyses of idealized aqua-planet simulations, the characteristics of the global high-resolution simulation in moist processes only developed near the boundary of the refined region. In contrast, the AMIP simulations with VR grids are able to reproduce the high-resolution characteristics across the refined domain, particularly in South America. This indicates the importance of finely resolved lower-boundary forcing such as topography and surface heterogeneity for the regional climate, and demonstrates the ability of the MPAS-A VR to replicate the large-scale moisture transport as simulated in the quasi-uniform high-resolution model. Outside of the refined domain, some upscale effects are detected through large-scale circulation but the overall climatic signals are not significant at regional scales. Our results provide support for the multi-resolution approach as a computationally efficient and physically consistent method for modeling regional climate.« less

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

Carini, Gabriella; Denes, Peter; Gruener, Sol

The Basic Energy Sciences (BES) X-ray and neutron user facilities attract more than 12,000 researchers each year to perform cutting-edge science at these state-of-the-art sources. While impressive breakthroughs in X-ray and neutron sources give us the powerful illumination needed to peer into the nano- to mesoscale world, a stumbling block continues to be the distinct lag in detector development, which is slowing progress toward data collection and analysis. Urgently needed detector improvements would reveal chemical composition and bonding in 3-D and in real time, allow researchers to watch “movies” of essential life processes as they happen, and make much moremore » efficient use of every X-ray and neutron produced by the source The immense scientific potential that will come from better detectors has triggered worldwide activity in this area. Europe in particular has made impressive strides, outpacing the United States on several fronts. Maintaining a vital U.S. leadership in this key research endeavor will require targeted investments in detector R&D and infrastructure. To clarify the gap between detector development and source advances, and to identify opportunities to maximize the scientific impact of BES user facilities, a workshop on Neutron and X-ray Detectors was held August 1-3, 2012, in Gaithersburg, Maryland. Participants from universities, national laboratories, and commercial organizations from the United States and around the globe participated in plenary sessions, breakout groups, and joint open-discussion summary sessions. Sources have become immensely more powerful and are now brighter (more particles focused onto the sample per second) and more precise (higher spatial, spectral, and temporal resolution). To fully utilize these source advances, detectors must become faster, more efficient, and more discriminating. In supporting the mission of today’s cutting-edge neutron and X-ray sources, the workshop identified six detector research challenges (and two computing hurdles that result from the corresponding increase in data volume) for the detector community to overcome in order to realize the full potential of BES neutron and X-ray facilities. Resolving these detector impediments will improve scientific productivity both by enabling new types of experiments, which will expand the scientific breadth at the X-ray and neutron facilities, and by potentially reducing the beam time required for a given experiment. These research priorities are summarized in the table below. Note that multiple, simultaneous detector improvements are often required to take full advantage of brighter sources. High-efficiency hard X-ray sensors: The fraction of incident particles that are actually detected defines detector efficiency. Silicon, the most common direct-detection X-ray sensor material, is (for typical sensor thicknesses) 100% efficient at 8 keV, 25%efficient at 20 keV, and only 3% efficient at 50 keV. Other materials are needed for hard X-rays. Replacement for 3He for neutron detectors: 3He has long been the neutron detection medium of choice because of its high cross section over a wide neutron energy range for the reaction 3He + n —> 3H + 1H + 0.764 MeV. 3He stockpiles are rapidly dwindling, and what is available can be had only at prohibitively high prices. Doped scintillators hold promise as ways to capture neutrons and convert them into light, although work is needed on brighter, more efficient scintillator solutions. Neutron detectors also require advances in speed and resolution. Fast-framing X-ray detectors: Today’s brighter X-ray sources make time-resolved studies possible. For example, hybrid X-ray pixel detectors, initially developed for particle physics, are becoming fairly mature X-ray detectors, with considerable development in Europe. To truly enable time-resolved studies, higher frame rates and dynamic range are required, and smaller pixel sizes are desirable. High-speed spectroscopic X-ray detectors: Improvements in the readout speed and energy resolution of X-ray detectors are essential to enable chemically sensitive microscopies. Advances would make it possible to take images with simultaneous spatial and chemical information. Very high-energy-resolution X-ray detectors: The energy resolution of semiconductor detectors, while suitable for a wide range of applications, is far less than what can be achieved with X-ray optics. A direct detector that could rival the energy resolution of optics could dramatically improve the efficiency of a multitude of experiments, as experiments are often repeated at a number of different energies. Very high-energy-resolution detectors could make these experiments parallel, rather than serial. Low-background, high-spatial-resolution neutron detectors: Low-background detectors would significantly improve experiments that probe excitations (phonons, spin excitations, rotation, and diffusion in polymers and molecular substances, etc.) in condensed matter. Improved spatial resolution would greatly benefit radiography, tomography, phase-contrast imaging, and holography. Improved acquisition and visualization tools: In the past, with the limited variety of slow detectors, it was straightforward to visualize data as it was being acquired (and adjust experimental conditions accordingly) to create a compact data set that the user could easily transport. As detector complexity and data rates explode, this becomes much more challenging. Three goals were identified as important for coping with the growing data volume from high-speed detectors: Facilitate better algorithm development. In particular, algorithms that can minimize the quantity of data stored. Improve community-driven mechanisms to reduce data protocols and enhance quantitative, interactive visualization tools. Develop and distribute community-developed, detector-specific simulation tools. Aim for parallelization to take advantage of high-performance analysis platforms. Improved analysis work flows: Standardize the format of metadata that accompanies detector data and describes the experimental setup and conditions. Develop a standardized user interface and software framework for analysis and data management. The diversity of detector improvements required is necessarily as broad as the range of scientific experimentation at BES facilities. This workshop identified a variety of avenues by which detector R&D can enable enhanced science at BES facilities. The Research Directions listed above will be addressed by focused R&D and detector engineering, both of which require specialized infrastructure and skills. While U.S. leadership in neutron and X-ray detectors lags behind other countries in several areas, significant talent exists across the complex. A forum of technical experts, facilities management, and BES could be a venue to provide further definition.« less

Evaluation of field methods for vertical high resolution aquifer characterization

NASA Astrophysics Data System (ADS)

Vienken, T.; Tinter, M.; Rogiers, B.; Leven, C.; Dietrich, P.

2012-12-01

The delineation and characterization of subsurface (hydro)-stratigraphic structures is one of the challenging tasks of hydrogeological site investigations. The knowledge about the spatial distribution of soil specific properties and hydraulic conductivity (K) is the prerequisite for understanding flow and fluid transport processes. This is especially true for heterogeneous unconsolidated sedimentary deposits with a complex sedimentary architecture. One commonly used approach to investigate and characterize sediment heterogeneity is soil sampling and lab analyses, e.g. grain size distribution. Tests conducted on 108 samples show that calculation of K based on grain size distribution is not suitable for high resolution aquifer characterization of highly heterogeneous sediments due to sampling effects and large differences of calculated K values between applied formulas (Vienken & Dietrich 2011). Therefore, extensive tests were conducted at two test sites under different geological conditions to evaluate the performance of innovative Direct Push (DP) based approaches for the vertical high resolution determination of K. Different DP based sensor probes for the in-situ subsurface characterization based on electrical, hydraulic, and textural soil properties were used to obtain high resolution vertical profiles. The applied DP based tools proved to be a suitable and efficient alternative to traditional approaches. Despite resolution differences, all of the applied methods captured the main aquifer structure. Correlation of the DP based K estimates and proxies with DP based slug tests show that it is possible to describe the aquifer hydraulic structure on less than a meter scale by combining DP slug test data and continuous DP measurements. Even though correlations are site specific and appropriate DP tools must be chosen, DP is reliable and efficient alternative for characterizing even strongly heterogeneous sites with complex structured sedimentary aquifers (Vienken et al. 2012). References: Vienken, T., Leven, C., and Dietrich, P. 2012. Use of CPT and other direct push methods for (hydro-) stratigraphic aquifer characterization — a field study. Canadian Geotechnical Journal, 49(2): 197-206. Vienken, T., and Dietrich, P. 2011. Field evaluation of methods for determining hydraulic conductivity from grain size data. Journal of Hydrology, 400(1-2): 58-71.

Non-Invasive Measurement of Frog Skin Reflectivity in High Spatial Resolution Using a Dual Hyperspectral Approach

PubMed Central

Liebisch, Frank; Walter, Achim; Greven, Hartmut; Rascher, Uwe

2013-01-01

Background Most spectral data for the amphibian integument are limited to the visible spectrum of light and have been collected using point measurements with low spatial resolution. In the present study a dual camera setup consisting of two push broom hyperspectral imaging systems was employed, which produces reflectance images between 400 and 2500 nm with high spectral and spatial resolution and a high dynamic range. Methodology/Principal Findings We briefly introduce the system and document the high efficiency of this technique analyzing exemplarily the spectral reflectivity of the integument of three arboreal anuran species (Litoria caerulea, Agalychnis callidryas and Hyla arborea), all of which appear green to the human eye. The imaging setup generates a high number of spectral bands within seconds and allows non-invasive characterization of spectral characteristics with relatively high working distance. Despite the comparatively uniform coloration, spectral reflectivity between 700 and 1100 nm differed markedly among the species. In contrast to H. arborea, L. caerulea and A. callidryas showed reflection in this range. For all three species, reflectivity above 1100 nm is primarily defined by water absorption. Furthermore, the high resolution allowed examining even small structures such as fingers and toes, which in A. callidryas showed an increased reflectivity in the near infrared part of the spectrum. Conclusion/Significance Hyperspectral imaging was found to be a very useful alternative technique combining the spectral resolution of spectrometric measurements with a higher spatial resolution. In addition, we used Digital Infrared/Red-Edge Photography as new simple method to roughly determine the near infrared reflectivity of frog specimens in field, where hyperspectral imaging is typically difficult. PMID:24058464

Development and Flight-testing of Astronomical Instrumentation for Future NASA Astrophysics Missions

NASA Astrophysics Data System (ADS)

France, Kevin

We propose a four year suborbital research program to continue the University of Colorado's efforts in the development and flight testing of instrument designs and critical path technologies for ultraviolet spectroscopy in support of future NASA Explorer, Probe-, and Flagship-class missions. This proposal builds on our existing program of high-resolution spectroscopy for the 100 - 160 nm bandpass with the development of a new high-efficiency imaging spectrograph operating in the same band. The ultimate goal of the University of Colorado ultraviolet rocket program is to develop the technical capabilities to enable a future, highly multiplexed ultraviolet spectrograph (with both high-resolution and imaging spectroscopy modes), e.g., an analog to the successful HST-STIS instrument, with an order-of-magnitude higher efficiency. We do this in the framework of a university led program where undergraduate, graduate, and postdoctoral training is paramount and cutting edge science investigations support our baseline technology development program. In the proposed effort, we will optimize our high-resolution (R > 100,000) echelle spectrograph payload (CHESS) with the first science flight of a new, large-format CCD array provided by our collaborators at JPL and Arizona State University. We will launch CHESS to study our local interstellar environment with spectral resolving power and bandpass that cannot be achieved with any suite of current or planned space missions. In parallel with the proposed science flights of CHESS, we will design, calibrate, and launch a new high-throughput imaging spectrograph (SISTINE); the first sub-arcsecond imaging, medium spectral resolution (R = 10,000), spectrograph ever flown with spectral coverage over the entire 100 - 160 nm bandpass. SISTINE incorporates several novel optical technologies that were highlighted as major hardware drivers for NASA's next large ultraviolet/optical/near-IR observatory by the 2014 Cosmic Origins Technology Report, including advanced mirror coatings with high broadband reflectivity (including > 20% efficiency gains below 115 nm), the first demonstration and flight test of these coatings on a shaped 0.5-meter telescope, and large-format, high-QE photon counting detectors. SISTINE will be launched to study the energetic radiation environment in the habitable zones around nearby low-mass exoplanet host stars, systems that are the top priority in NASA's search for the signatures of biological activity in the coming decade. SISTINE addresses the highest science priority in the 2010 Astronomy and Astrophysics Decadal Survey and is a crucial step towards meeting NASA's technology needs for future space observatories.

Application of CHESS single-bounce capillaries at synchrotron beamlines

NASA Astrophysics Data System (ADS)

Huang, R.; Szebenyi, T.; Pfeifer, M.; Woll, A.; Smilgies, D.-M.; Finkelstein, K.; Dale, D.; Wang, Y.; Vila-Comamala, J.; Gillilan, R.; Cook, M.; Bilderback, D. H.

2014-03-01

Single-bounce capillaries are achromatic X-ray focusing optics that can provide efficient and high demagnification focusing with large numerical apertures. Capillary fabrication at CHESS can be customized according to specific application requirements. Exemplary applications are reviewed in this paper, as well as recent progress on condensers for high-resolution transmission X-ray microscopy and small focal size capillaries.

High fat diet leads to changes in metabolite patterns in pig plasma, fecal, and urine samples detected by a ultra-high performance liquid chromatography tandem with high resolution mass spectrometry metabolomic study

USDA-ARS?s Scientific Manuscript database

Non-targeted metabolite profiling can identify robust biological markers of dietary exposure that can lead to a better understanding of causal interactions between diet and health. In this study, pigs were used as an animal model to develop an efficient procedure to discover metabolites in biolog...

Assessing the value of different data sets and modeling schemes for flow and transport simulations

NASA Astrophysics Data System (ADS)

Hyndman, D. W.; Dogan, M.; Van Dam, R. L.; Meerschaert, M. M.; Butler, J. J., Jr.; Benson, D. A.

2014-12-01

Accurate modeling of contaminant transport has been hampered by an inability to characterize subsurface flow and transport properties at a sufficiently high resolution. However mathematical extrapolation combined with different measurement methods can provide realistic three-dimensional fields of highly heterogeneous hydraulic conductivity (K). This study demonstrates an approach to evaluate the time, cost, and efficiency of subsurface K characterization. We quantify the value of different data sets at the highly heterogeneous Macro Dispersion Experiment (MADE) Site in Mississippi, which is a flagship test site that has been used for several macro- and small-scale tracer tests that revealed non-Gaussian tracer behavior. Tracer data collected at the site are compared to models that are based on different types and resolution of geophysical and hydrologic data. We present a cost-benefit analysis of several techniques including: 1) flowmeter K data, 2) direct-push K data, 3) ground penetrating radar, and 4) two stochastic methods to generate K fields. This research provides an initial assessment of the level of data necessary to accurately simulate solute transport with the traditional advection dispersion equation; it also provides a basis to design lower cost and more efficient remediation schemes at highly heterogeneous sites.

A High-Resolution Time-of-Flight Clinical PET Detection System Using a Gapless PMT-Quadrant-Sharing Method

NASA Astrophysics Data System (ADS)

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

2015-10-01

We developed a high-resolution Photomultiplier-Quadrant-Sharing (PQS) PET system for human imaging. This system is made up of 24 detector panels. Each panel (bank) consists of 3 ×7 detector blocks, and each block has 16 ×16 LYSO crystals of 2.35 ×2.35 ×15.2 mm3. We used a novel detector-grinding scheme that is compatible with the PQS detector-pixel-decoding requirements to make a gapless cylindrical detector ring for maximizing detection efficiency while delivering an ultrahigh spatial-resolution for a whole-body PET camera with a ring diameter of 87 cm and axial field of view of 27.6 cm. This grinding scheme enables two adjacent gapless panels to share one row of the PMTs to extend the PQS configuration beyond one panel and thus maximize the economic benefit (in PMT usage) of the PQS design. The entire detector ring has 129,024 crystals, all of which are clearly decoded using only 576 PMTs (38-mm diameter). Thus, each PMT on average decodes 224 crystals to achieve a high crystal-pitch resolution of 2.44 mm ×2.44 mm. The detector blocks were mass-produced with our slab-sandwich-slice technique using a set of optimized mirror-film patterns (between crystals) to maximize light output and achieve high spatial and timing resolution. This detection system with time-of-flight capability was placed in a human PET/CT gantry. The reconstructed image resolution of the system was about 2.87 mm using 2D-filtered back-projection. The time-of-flight resolution was 473 ps. The preliminary images of phantoms and clinical studies presented in this work demonstrate the capability of this new PET/CT system to produce high-quality images.

Climate Modeling: Ocean Cavities below Ice Shelves

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

Petersen, Mark Roger

The Accelerated Climate Model for Energy (ACME), a new initiative by the U.S. Department of Energy, includes unstructured-mesh ocean, land-ice, and sea-ice components using the Model for Prediction Across Scales (MPAS) framework. The ability to run coupled high-resolution global simulations efficiently on large, high-performance computers is a priority for ACME. Sub-ice shelf ocean cavities are a significant new capability in ACME, and will be used to better understand how changing ocean temperature and currents influence glacial melting and retreat. These simulations take advantage of the horizontal variable-resolution mesh and adaptive vertical coordinate in MPAS-Ocean, in order to place high resolutionmore » below ice shelves and near grounding lines.« less

New materials for high-energy-resolution x-ray optics

DOE PAGES

Yavas, Hasan; Sutter, John P.; Gog, Thomas; ...

2017-06-09

The use of crystals other than silicon for x-ray optics is becoming more common for many challenging experiments such as resonant inelastic x-ray scattering and nuclear resonant scattering. As more—and more specialized—spectrometers become available at many synchrotron radiation facilities, interest in pushing the limits of experimental energy resolution has increased. The potentially large improvements in resolution and efficiency that nonsilicon optics offer are beginning to be realized. Furthermore, this article covers the background and state of the art for nonsilicon crystal optics with a focus on a resolution of 10 meV or better, concentrating on compounds that form trigonal crystals,more » including sapphire, quartz, and lithium niobate, rather than the more conventional cubic materials, including silicon, diamond, and germanium.« less

A method to improve the range resolution in stepped frequency continuous wave radar

NASA Astrophysics Data System (ADS)

Kaczmarek, Paweł

2018-04-01

In the paper one of high range resolution methods - Aperture Sampling - was analysed. Unlike MUSIC based techniques it proved to be very efficient in terms of achieving unambiguous synthetic range profile for ultra-wideband stepped frequency continuous wave radar. Assuming that minimal distance required to separate two targets in depth (distance) corresponds to -3 dB width of received echo, AS provided a 30,8 % improvement in range resolution in analysed scenario, when compared to results of applying IFFT. Output data is far superior in terms of both improved range resolution and reduced side lobe level than used typically in this area Inverse Fourier Transform. Furthermore it does not require prior knowledge or an estimate of number of targets to be detected in a given scan.

Chemoenzymatic Dynamic Kinetic Resolution: A Powerful Tool for the Preparation of Enantiomerically Pure Alcohols and Amines

PubMed Central

2015-01-01

Chemoenzymatic dynamic kinetic resolution (DKR) constitutes a convenient and efficient method to access enantiomerically pure alcohol and amine derivatives. This Perspective highlights the work carried out within this field during the past two decades and pinpoints important avenues for future research. First, the Perspective will summarize the more developed area of alcohol DKR, by delineating the way from the earliest proof-of-concept protocols to the current state-of-the-art systems that allows for the highly efficient and selective preparation of a wide range of enantiomerically pure alcohol derivatives. Thereafter, the Perspective will focus on the more challenging DKR of amines, by presenting the currently available homogeneous and heterogeneous methods and their respective limitations. In these two parts, significant attention will be dedicated to the design of efficient racemization methods as an important means of developing milder DKR protocols. In the final part of the Perspective, a brief overview of the research that has been devoted toward improving enzymes as biocatalysts is presented. PMID:25730714

Immobilized polysaccharide derivatives: chiral packing materials for efficient HPLC resolution.

PubMed

Ikai, Tomoyuki; Yamamoto, Chiyo; Kamigaito, Masami; Okamoto, Yoshio

2007-01-01

Polysaccharide-based chiral packing materials (CPMs) for high-performance liquid chromatography have frequently been used not only to determine the enantiomeric excess of chiral compounds but also to preparatively resolve a wide range of racemates. However, these CPMs can be used with only a limited number of solvents as mobile phases because some organic solvents, such as tetrahydrofuran, chloroform, and so on, dissolve or swell the polysaccharide derivatives coated on a support, e.g., silica gel, and destroy their packed columns. The limitation of mobile phase selection is sometimes a serious problem for the efficient analytical and preparative resolution of enantiomers. This defect can be resolved by the immobilization of the polysaccharide derivatives onto silica gel. Efficient immobilizations have been attained through the radical copolymerization of the polysaccharide derivatives bearing small amounts of polymerizable residues and also through the polycondensation of the polysaccharide derivatives containing a few percent of 3-(triethoxysilyl)propyl residue. (c) 2007 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

Cognitive control predicted by color vision, and vice versa.

PubMed

Colzato, Lorenza S; Sellaro, Roberta; Hulka, Lea M; Quednow, Boris B; Hommel, Bernhard

2014-09-01

One of the most important functions of cognitive control is to continuously adapt cognitive processes to changing and often conflicting demands of the environment. Dopamine (DA) has been suggested to play a key role in the signaling and resolution of such response conflict. Given that DA is found in high concentration in the retina, color vision discrimination has been suggested as an index of DA functioning and in particular blue-yellow color vision impairment (CVI) has been used to indicate a central hypodopaminergic state. We used color discrimination (indexed by the total color distance score; TCDS) to predict individual differences in the cognitive control of response conflict, as reflected by conflict-resolution efficiency in an auditory Simon task. As expected, participants showing better color discrimination were more efficient in resolving response conflict. Interestingly, participants showing a blue-yellow CVI were associated with less efficiency in handling response conflict. Our findings indicate that color vision discrimination might represent a promising predictor of cognitive controlability in healthy individuals. Copyright © 2014 Elsevier Ltd. All rights reserved.

Efficient single photon detection by quantum dot resonant tunneling diodes.

PubMed

Blakesley, J C; See, P; Shields, A J; Kardynał, B E; Atkinson, P; Farrer, I; Ritchie, D A

2005-02-18

We demonstrate that the resonant tunnel current through a double-barrier structure is sensitive to the capture of single photoexcited holes by an adjacent layer of quantum dots. This phenomenon could allow the detection of single photons with low dark count rates and high quantum efficiencies. The magnitude of the sensing current may be controlled via the thickness of the tunnel barriers. Larger currents give improved signal to noise and allow sub-mus photon time resolution.

Lineshape spectroscopy with a very high resolution, very high signal-to-noise crystal spectrometer

DOE PAGES

Beiersdorfer, P.; Magee, E. W.; Brown, G. V.; ...

2016-06-06

Here, we have developed a high-resolution x-ray spectrometer for measuring the shapes of spectral lines produced from laser-irradiated targets on the Orion laser facility. The instrument utilizes a spherically bent crystal geometry to spatially focus and spectrally analyze photons from foil or microdot targets. The high photon collection efficiency resulting from its imaging properties allows the instrument to be mounted outside the Orion chamber, where it is far less sensitive to particles, hard x-rays, or electromagnetic pulses than instruments housed close to the target chamber center in ten-inch manipulators. Moreover, Bragg angles above 50° are possible, which provide greatly improvedmore » spectral resolution compared to radially viewing, near grazing-incidence crystal spectrometers. These properties make the new instrument an ideal lineshape diagnostic for determining plasma temperature and density. We describe its calibration on the Livermore electron beam ion trap facility and present spectral data of the K-shell emission from highly charged sulfur produced by long-pulse as well as short-pulse beams on the Orion laser in the United Kingdom.« less

Lineshape spectroscopy with a very high resolution, very high signal-to-noise crystal spectrometer

NASA Astrophysics Data System (ADS)

Beiersdorfer, P.; Magee, E. W.; Brown, G. V.; Chen, H.; Emig, J.; Hell, N.; Bitter, M.; Hill, K. W.; Allan, P.; Brown, C. R. D.; Hill, M. P.; Hoarty, D. J.; Hobbs, L. M. R.; James, S. F.

2016-06-01

We have developed a high-resolution x-ray spectrometer for measuring the shapes of spectral lines produced from laser-irradiated targets on the Orion laser facility. The instrument utilizes a spherically bent crystal geometry to spatially focus and spectrally analyze photons from foil or microdot targets. The high photon collection efficiency resulting from its imaging properties allows the instrument to be mounted outside the Orion chamber, where it is far less sensitive to particles, hard x-rays, or electromagnetic pulses than instruments housed close to the target chamber center in ten-inch manipulators. Moreover, Bragg angles above 50° are possible, which provide greatly improved spectral resolution compared to radially viewing, near grazing-incidence crystal spectrometers. These properties make the new instrument an ideal lineshape diagnostic for determining plasma temperature and density. We describe its calibration on the Livermore electron beam ion trap facility and present spectral data of the K-shell emission from highly charged sulfur produced by long-pulse as well as short-pulse beams on the Orion laser in the United Kingdom.

Lineshape spectroscopy with a very high resolution, very high signal-to-noise crystal spectrometer

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

Beiersdorfer, P.; Magee, E. W.; Brown, G. V.

2016-06-15

We have developed a high-resolution x-ray spectrometer for measuring the shapes of spectral lines produced from laser-irradiated targets on the Orion laser facility. The instrument utilizes a spherically bent crystal geometry to spatially focus and spectrally analyze photons from foil or microdot targets. The high photon collection efficiency resulting from its imaging properties allows the instrument to be mounted outside the Orion chamber, where it is far less sensitive to particles, hard x-rays, or electromagnetic pulses than instruments housed close to the target chamber center in ten-inch manipulators. Moreover, Bragg angles above 50° are possible, which provide greatly improved spectralmore » resolution compared to radially viewing, near grazing-incidence crystal spectrometers. These properties make the new instrument an ideal lineshape diagnostic for determining plasma temperature and density. We describe its calibration on the Livermore electron beam ion trap facility and present spectral data of the K-shell emission from highly charged sulfur produced by long-pulse as well as short-pulse beams on the Orion laser in the United Kingdom.« less

A novel high resolution, high sensitivity SPECT detector for molecular imaging of cardiovascular diseases

NASA Astrophysics Data System (ADS)

Cusanno, F.; Argentieri, A.; Baiocchi, M.; Colilli, S.; Cisbani, E.; De Vincentis, G.; Fratoni, R.; Garibaldi, F.; Giuliani, F.; Gricia, M.; Lucentini, M.; Magliozzi, M. L.; Majewski, S.; Marano, G.; Musico, P.; Musumeci, M.; Santavenere, F.; Torrioli, S.; Tsui, B. M. W.; Vitelli, L.; Wang, Y.

2010-05-01

Cardiovascular diseases are the most common cause of death in western countries. Understanding the rupture of vulnerable atherosclerotic plaques and monitoring the effect of innovative therapies of heart failure is of fundamental importance. A flexible, high resolution, high sensitivity detector system for molecular imaging with radionuclides on small animal models has been designed for this aim. A prototype has been built using tungsten pinhole and LaBr3(Ce) scintillator coupled to Hamamatsu Flat Panel PMTs. Compact individual-channel readout has been designed, built and tested. Measurements with phantoms as well as pilot studies on mice have been performed, the results show that the myocardial perfusion in mice can be determined with sufficient precision. The detector will be improved replacing the Hamamatsu Flat Panel with Silicon Photomultipliers (SiPMs) to allow integration of the system with MRI scanners. Application of LaBr3(Ce) scintillator coupled to photosensor with high photon detection efficiency and excellent energy resolution will allow dual-label imaging to monitor simultaneously the cardiac perfusion and the molecular targets under investigation during the heart therapy.

Mass Spectrometric Imaging Using Laser Ablation and Solvent Capture by Aspiration (LASCA)

NASA Astrophysics Data System (ADS)

Brauer, Jonathan I.; Beech, Iwona B.; Sunner, Jan

2015-09-01

A novel interface for ambient, laser ablation-based mass spectrometric imaging (MSI) referred to as laser ablation and solvent capture by aspiration (LASCA) is presented and its performance demonstrated using selected, unaltered biological materials. LASCA employs a pulsed 2.94 μm laser beam for specimen ablation. Ablated materials in the laser plumes are collected on a hanging solvent droplet with electric field-enhanced trapping, followed by aspiration of droplets and remaining plume material in the form of a coarse aerosol into a collection capillary. The gas and liquid phases are subsequently separated in a 10 μL-volume separatory funnel, and the solution is analyzed with electrospray ionization in a high mass resolution Q-ToF mass spectrometer. The LASCA system separates the sampling and ionization steps in MSI and combines high efficiencies of laser plume sampling and of electrospray ionization (ESI) with high mass resolution MS. Up to 2000 different compounds are detected from a single ablation spot (pixel). Using the LASCA platform, rapid (6 s per pixel), high sensitivity, high mass-resolution ambient imaging of "as-received" biological material is achieved routinely and reproducibly.

Combined dispersive/interference spectroscopy for producing a vector spectrum

DOEpatents

Erskine, David J.

2002-01-01

A method of measuring the spectral properties of broadband waves that combines interferometry with a wavelength disperser having many spectral channels to produce a fringing spectrum. Spectral mapping, Doppler shifts, metrology of angles, distances and secondary effects such as temperature, pressure, and acceleration which change an interferometer cavity length can be measured accurately by a compact instrument using broadband illumination. Broadband illumination avoids the fringe skip ambiguities of monochromatic waves. The interferometer provides arbitrarily high spectral resolution, simple instrument response, compactness, low cost, high field of view and high efficiency. The inclusion of a disperser increases fringe visibility and signal to noise ratio over an interferometer used alone for broadband waves. The fringing spectrum is represented as a wavelength dependent 2-d vector, which describes the fringe amplitude and phase. Vector mathematics such as generalized dot products rapidly computes average broadband phase shifts to high accuracy. A Moire effect between the interferometer's sinusoidal transmission and the illumination heterodynes high resolution spectral detail to low spectral detail, allowing the use of a low resolution disperser. Multiple parallel interferometer cavities of fixed delay allow the instantaneous mapping of a spectrum, with an instrument more compact for the same spectral resolution than a conventional dispersive spectrometer, and not requiring a scanning delay.

Effects of Reduced Terrestrial LiDAR Point Density on High-Resolution Grain Crop Surface Models in Precision Agriculture

PubMed Central

Hämmerle, Martin; Höfle, Bernhard

2014-01-01

3D geodata play an increasingly important role in precision agriculture, e.g., for modeling in-field variations of grain crop features such as height or biomass. A common data capturing method is LiDAR, which often requires expensive equipment and produces large datasets. This study contributes to the improvement of 3D geodata capturing efficiency by assessing the effect of reduced scanning resolution on crop surface models (CSMs). The analysis is based on high-end LiDAR point clouds of grain crop fields of different varieties (rye and wheat) and nitrogen fertilization stages (100%, 50%, 10%). Lower scanning resolutions are simulated by keeping every n-th laser beam with increasing step widths n. For each iteration step, high-resolution CSMs (0.01 m2 cells) are derived and assessed regarding their coverage relative to a seamless CSM derived from the original point cloud, standard deviation of elevation and mean elevation. Reducing the resolution to, e.g., 25% still leads to a coverage of >90% and a mean CSM elevation of >96% of measured crop height. CSM types (maximum elevation or 90th-percentile elevation) react differently to reduced scanning resolutions in different crops (variety, density). The results can help to assess the trade-off between CSM quality and minimum requirements regarding equipment and capturing set-up. PMID:25521383

Analysis of uniformity of as prepared and irradiated S.I. GaAs radiation detectors

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

Nava, F.; Vanni, P.; Canali, C.

1998-06-01

SI (semi-insulating) LEC (Liquid Encapsulated Czochralsky) GaAs (gallium arsenide) Schottky barrier detectors have been irradiated with high energy protons (24 GeV/c, fluence up to 16.45 {times} 10{sup 13} p/cm{sup 2}). The detectors have been characterized in terms of I/V curves, charge collection efficiency (cce) for incident 5.48 MeV {alpha}-, 2 MeV proton and minimum ionizing {beta}-particles and of cce maps by microprobe technique IBIC (Ion Beam Induced Charge). At the highest fluence a significant degradation of the electron and hole collection efficiencies and a remarkable improvement of the Full Width Half Maximum (FWHM) energy resolution have been measured with {alpha}-more » and proton particles. Furthermore, the reduction in the cce is greater than the one measured with {beta}-particles and the energy resolution worsens with increasing the applied bias, V{sub a}, above the voltage V{sub d} necessary to extend the electric field al the way to the ohmic contact. On the contrary, in the unirradiated detectors the charge collection efficiencies with {alpha}-, {beta}- and proton particles are quite similar and the energy resolution improves with increasing V{sub a} > V{sub d}. IBIC spectra and IBIC space maps obtained by scanning a focused (8 {micro}m{sup 2}) 2 MeV proton microbeam on front (Schottky) and back (ohmic) contacts, support the observed electric field dependence of the energy resolution both in unirradiated and most irradiated detectors. The results obtained let them explain the effect of the electric field strength and the plasma on the collection of the charge carriers and the FWHM energy resolution.« less

EPA’s Non-Targeted Analysis Research Program: Expanding public data resources in support of exposure science

EPA Science Inventory

Suspect screening (SSA) and non-targeted analysis (NTA) methods using high-resolution mass spectrometry (HRMS) offer new approaches to efficiently generate exposure data for chemicals in a variety of environmental and biological media. These techniques aid characterization of the...

Fully Solution-Processed Tandem White Quantum-Dot Light-Emitting Diode with an External Quantum Efficiency Exceeding 25.

PubMed

Jiang, Congbiao; Zou, Jianhua; Liu, Yu; Song, Chen; He, Zhiwei; Zhong, Zhenji; Wang, Jian; Yip, Hin-Lap; Peng, Junbiao; Cao, Yong

2018-06-15

Solution-processed electroluminescent tandem white quantum-dot light-emitting diodes (TWQLEDs) have the advantages of being low-cost and high-efficiency and having a wide color gamut combined with color filters, making this a promising backlight technology for high-resolution displays. However, TWQLEDs are rarely reported due to the challenge of designing device structures and the deterioration of film morphology with component layers that can be deposited from solutions. Here, we report an interconnecting layer with the optical, electrical, and mechanical properties required for fully solution-processed TWQLED. The optimized TWQLEDs exhibit a state-of-the-art current efficiency as high as 60.4 cd/A and an extremely high external quantum efficiency of 27.3% at a luminance of 100 000 cd/m 2 . A high color gamut of 124% NTSC 1931 standard can be achieved when combined with commercial color filters. These results represent the highest performance for solution-processed WQLEDs, unlocking the great application potential of TWQLEDs as backlights for new-generation displays.

Spatial Resolution Versus Data Acquisition Efficiency in Mapping an Inhomogeneous System with Species Diffusion

DOE PAGES

Chen, Fengxiang; Zhang, Yong; Gfroerer, T. H.; ...

2015-06-02

Traditionally, spatially-resolved photoluminescence (PL) has been performed using a point-by-point scan mode with both excitation and detection occurring at the same spatial location. But with the availability of high quality detector arrays like CCDs, an imaging mode has become popular for performing spatially-resolved PL. By illuminating the entire area of interest and collecting the data simultaneously from all spatial locations, the measurement efficiency can be greatly improved. However, this new approach has proceeded under the implicit assumption of comparable spatial resolution. We show here that when carrier diffusion is present, the spatial resolution can actually differ substantially between the twomore » modes, with the less efficient scan mode being far superior. We apply both techniques in investigation of defects in a GaAs epilayer – where isolated singlet and doublet dislocations can be identified. A superposition principle is developed for solving the diffusion equation to extract the intrinsic carrier diffusion length, which can be applied to a system with arbitrarily distributed defects. The understanding derived from this work is significant for a broad range of problems in physics and beyond (for instance biology) – whenever the dynamics of generation, diffusion, and annihilation of species can be probed with either measurement mode.« less

High-Efficiency InGaN/GaN Quantum Well-Based Vertical Light-Emitting Diodes Fabricated on β-Ga2O3 Substrate.

PubMed

Muhammed, Mufasila M; Alwadai, Norah; Lopatin, Sergei; Kuramata, Akito; Roqan, Iman S

2017-10-04

We demonstrate a state-of-the-art high-efficiency GaN-based vertical light-emitting diode (VLED) grown on a transparent and conductive (-201)-oriented (β-Ga 2 O 3 ) substrate, obtained using a straightforward growth process that does not require a high-cost lift-off technique or complex fabrication process. The high-resolution scanning transmission electron microscopy (STEM) images confirm that we produced high quality upper layers, including a multiquantum well (MQW) grown on the masked β-Ga 2 O 3 substrate. STEM imaging also shows a well-defined MQW without InN diffusion into the barrier. Electroluminescence (EL) measurements at room temperature indicate that we achieved a very high internal quantum efficiency (IQE) of 78%; at lower temperatures, IQE reaches ∼86%. The photoluminescence (PL) and time-resolved PL analysis indicate that, at a high carrier injection density, the emission is dominated by radiative recombination with a negligible Auger effect; no quantum-confined Stark effect is observed. At low temperatures, no efficiency droop is observed at a high carrier injection density, indicating the superior VLED structure obtained without lift-off processing, which is cost-effective for large-scale devices.

All-fiber upconversion high spectral resolution wind lidar using a Fabry-Perot interferometer.

PubMed

Shangguan, Mingjia; Xia, Haiyun; Wang, Chong; Qiu, Jiawei; Shentu, Guoliang; Zhang, Qiang; Dou, Xiankang; Pan, Jian-Wei

2016-08-22

An all-fiber, micro-pulse and eye-safe high spectral resolution wind lidar (HSRWL) at 1.5 μm is proposed and demonstrated by using a pair of upconversion single-photon detectors and a fiber Fabry-Perot scanning interferometer (FFP-SI). In order to improve the optical detection efficiency, both the transmission spectrum and the reflection spectrum of the FFP-SI are used for spectral analyses of the aerosol backscatter and the reference laser pulse. Taking advantages of high signal-to-noise ratio of the detectors and high spectral resolution of the FFP-SI, the center frequencies and the bandwidths of spectra of the aerosol backscatter are obtained simultaneously. Continuous LOS wind observations are carried out on two days at Hefei (31.843 °N, 117.265 °E), China. The horizontal detection range of 4 km is realized with temporal resolution of 1 minute. The spatial resolution is switched from 30 m to 60 m at distance of 1.8 km. In a comparison experiment, LOS wind measurements from the HSRWL show good agreement with the results from an ultrasonic wind sensor (Vaisala windcap WMT52). An empirical method is adopted to evaluate the precision of the measurements. The standard deviation of the wind speed is 0.76 m/s at 1.8 km. The standard deviation of bandwidth variation is 2.07 MHz at 1.8 km.

Fabrication and performance of efficient thin circular polarization gratings with Bragg properties using bulk photo-alignment of a liquid crystalline polymer

NASA Astrophysics Data System (ADS)

Sakhno, Oksana; Gritsai, Yuri; Sahm, Hagen; Stumpe, Joachim

2018-03-01

Thin circular polarization gratings, characterized by high diffraction efficiency and large, up to 42°, diffraction angles were created by polarization holography for the first time. The high efficiency of the gratings is the result of the specific properties of a photo-crosslinkable liquid crystalline polymer and a two-step photochemical/thermal processing procedure. A diffraction efficiency of up to 98% at 532 nm has been achieved for gratings with periods of 700 nm. In contrast to polarization gratings with larger periods these gratings exhibit Bragg properties. So one beam is either transmitted or diffracted depending on the direction of the circular polarization of the incident light, whereas the maximal diffraction efficiency is achieved only at the proper incident angle. The fabrication procedure consists of holographic exposure of the film at room temperature which provides the photo-selective cycloaddition of cinnamic ester groups. Upon subsequent thermal annealing above T g bulk photo-alignment of the LC polymer film occurs enhancing the optical anisotropy within the grating. The holographic patterning provides high spatial resolution, the arbitrary orientation of the LC director as well as high optical quality, thermal and chemical stability of the final gratings. Highly efficient symmetric and slanted circular polarization gratings were fabricated with the proposed technique.

Fabrication of high-resolution x-ray diffractive optics at King's College London

NASA Astrophysics Data System (ADS)

Charalambous, Pambos S.; Anastasi, Peter A. F.; Burge, Ronald E.; Popova, Katia

1995-09-01

The fabrication of high resolution x-ray diffractive optics, and Fresnel zone plates (ZPs) in particular, is a very demanding multifaceted technological task. The commissioning of more (and brighter) synchrotron radiation sources, has increased the number of x-ray imaging beam lines world wide. The availability of cheaper and more effective laboratory x-ray sources, has further increased the number of laboratories involved in x-ray imaging. The result is an ever increasing demand for x-ray optics with a very wide range of specifications, reflecting the particular type of x-ray imaging performed at different laboratories. We have been involved in all aspects of high resolution nanofabrication for a number of years, and we have explored many different methods of lithography, which, although unorthodox, open up possibilities, and increase our flexibility for the fabrication of different diffractive optical elements, as well as other types of nanostructures. The availability of brighter x-ray sources, means that the diffraction efficiency of the ZPs is becoming of secondary importance, a trend which will continue in the future. Resolution, however, is important and will always remain so. Resolution is directly related to the accuracy af pattern generation, as well as the ability to draw fine lines. This is the area towards which we have directed most of our efforts so far.

An Efficient Adaptive Window Size Selection Method for Improving Spectrogram Visualization.

PubMed

Nisar, Shibli; Khan, Omar Usman; Tariq, Muhammad

2016-01-01

Short Time Fourier Transform (STFT) is an important technique for the time-frequency analysis of a time varying signal. The basic approach behind it involves the application of a Fast Fourier Transform (FFT) to a signal multiplied with an appropriate window function with fixed resolution. The selection of an appropriate window size is difficult when no background information about the input signal is known. In this paper, a novel empirical model is proposed that adaptively adjusts the window size for a narrow band-signal using spectrum sensing technique. For wide-band signals, where a fixed time-frequency resolution is undesirable, the approach adapts the constant Q transform (CQT). Unlike the STFT, the CQT provides a varying time-frequency resolution. This results in a high spectral resolution at low frequencies and high temporal resolution at high frequencies. In this paper, a simple but effective switching framework is provided between both STFT and CQT. The proposed method also allows for the dynamic construction of a filter bank according to user-defined parameters. This helps in reducing redundant entries in the filter bank. Results obtained from the proposed method not only improve the spectrogram visualization but also reduce the computation cost and achieves 87.71% of the appropriate window length selection.

Multispectral image enhancement processing for microsat-borne imager

NASA Astrophysics Data System (ADS)

Sun, Jianying; Tan, Zheng; Lv, Qunbo; Pei, Linlin

2017-10-01

With the rapid development of remote sensing imaging technology, the micro satellite, one kind of tiny spacecraft, appears during the past few years. A good many studies contribute to dwarfing satellites for imaging purpose. Generally speaking, micro satellites weigh less than 100 kilograms, even less than 50 kilograms, which are slightly larger or smaller than the common miniature refrigerators. However, the optical system design is hard to be perfect due to the satellite room and weight limitation. In most cases, the unprocessed data captured by the imager on the microsatellite cannot meet the application need. Spatial resolution is the key problem. As for remote sensing applications, the higher spatial resolution of images we gain, the wider fields we can apply them. Consequently, how to utilize super resolution (SR) and image fusion to enhance the quality of imagery deserves studying. Our team, the Key Laboratory of Computational Optical Imaging Technology, Academy Opto-Electronics, is devoted to designing high-performance microsat-borne imagers and high-efficiency image processing algorithms. This paper addresses a multispectral image enhancement framework for space-borne imagery, jointing the pan-sharpening and super resolution techniques to deal with the spatial resolution shortcoming of microsatellites. We test the remote sensing images acquired by CX6-02 satellite and give the SR performance. The experiments illustrate the proposed approach provides high-quality images.

Whole mouse cryo-imaging

NASA Astrophysics Data System (ADS)

Wilson, David; Roy, Debashish; Steyer, Grant; Gargesha, Madhusudhana; Stone, Meredith; McKinley, Eliot

2008-03-01

The Case cryo-imaging system is a section and image system which allows one to acquire micron-scale, information rich, whole mouse color bright field and molecular fluorescence images of an entire mouse. Cryo-imaging is used in a variety of applications, including mouse and embryo anatomical phenotyping, drug delivery, imaging agents, metastastic cancer, stem cells, and very high resolution vascular imaging, among many. Cryo-imaging fills the gap between whole animal in vivo imaging and histology, allowing one to image a mouse along the continuum from the mouse -> organ -> tissue structure -> cell -> sub-cellular domains. In this overview, we describe the technology and a variety of exciting applications. Enhancements to the system now enable tiled acquisition of high resolution images to cover an entire mouse. High resolution fluorescence imaging, aided by a novel subtraction processing algorithm to remove sub-surface fluorescence, makes it possible to detect fluorescently-labeled single cells. Multi-modality experiments in Magnetic Resonance Imaging and Cryo-imaging of a whole mouse demonstrate superior resolution of cryo-images and efficiency of registration techniques. The 3D results demonstrate the novel true-color volume visualization tools we have developed and the inherent advantage of cryo-imaging in providing unlimited depth of field and spatial resolution. The recent results continue to demonstrate the value cryo-imaging provides in the field of small animal imaging research.

Demosaiced pixel super-resolution in digital holography for multiplexed computational color imaging on-a-chip (Conference Presentation)

NASA Astrophysics Data System (ADS)

Wu, Yichen; Zhang, Yibo; Luo, Wei; Ozcan, Aydogan

2017-03-01

Digital holographic on-chip microscopy achieves large space-bandwidth-products (e.g., >1 billion) by making use of pixel super-resolution techniques. To synthesize a digital holographic color image, one can take three sets of holograms representing the red (R), green (G) and blue (B) parts of the spectrum and digitally combine them to synthesize a color image. The data acquisition efficiency of this sequential illumination process can be improved by 3-fold using wavelength-multiplexed R, G and B illumination that simultaneously illuminates the sample, and using a Bayer color image sensor with known or calibrated transmission spectra to digitally demultiplex these three wavelength channels. This demultiplexing step is conventionally used with interpolation-based Bayer demosaicing methods. However, because the pixels of different color channels on a Bayer image sensor chip are not at the same physical location, conventional interpolation-based demosaicing process generates strong color artifacts, especially at rapidly oscillating hologram fringes, which become even more pronounced through digital wave propagation and phase retrieval processes. Here, we demonstrate that by merging the pixel super-resolution framework into the demultiplexing process, such color artifacts can be greatly suppressed. This novel technique, termed demosaiced pixel super-resolution (D-PSR) for digital holographic imaging, achieves very similar color imaging performance compared to conventional sequential R,G,B illumination, with 3-fold improvement in image acquisition time and data-efficiency. We successfully demonstrated the color imaging performance of this approach by imaging stained Pap smears. The D-PSR technique is broadly applicable to high-throughput, high-resolution digital holographic color microscopy techniques that can be used in resource-limited-settings and point-of-care offices.

A front-end readout mixed chip for high-efficiency small animal PET imaging

NASA Astrophysics Data System (ADS)

Ollivier-Henry, N.; Berst, J. D.; Colledani, C.; Hu-Guo, Ch.; Mbow, N. A.; Staub, D.; Guyonnet, J. L.; Hu, Y.

2007-02-01

Today, the main challenge of Positron Emission Tomography (PET) systems dedicated to small animal imaging is to obtain high detection efficiency and a highly accurate localization of radioisotopes. If we focus only on the PET characteristics such as the spatial resolution, its accuracy depends on the design of detector and on the electronics readout system as well. In this paper, we present a new design of such readout system with full custom submicrometer CMOS implementation. The front end chip consists of two main blocks from which the energy information and the time stamp with subnanosecond resolution can be obtained. In our A Multi-Modality Imaging System for Small Animal (AMISSA) PET system design, a matrix of LYSO crystals has to be read at each end by a 64 channels multianode photomultiplier tube. A specific readout electronic has been developed at the Hubert Curien Multidisciplinary Institute (IPHC, France). The architecture of this readout for the energy information detection is composed of a low-noise preamplifier, a CR-RC shaper and an analogue memory. In order to obtain the required dynamic range from 15 to 650 photoelectrons with good linearity, a current mode approach has been chosen for the preamplifier. To detect the signal with a temporal resolution of 1 ns, a comparator with a very low threshold (˜0.3 photoelectron) has been implemented. It gives the time reference of arrival signal coming from the detector. In order to obtain the time coincidence with a temporal resolution of 1 ns, a Time-to-Digital Converter (TDC) based on a Delay-Locked-Loop (DLL) has been designed. The chip is fabricated with AMS 0.35 μm process. The ASIC architecture and some simulation results will be presented in the paper.

Analyzing blinking effects in super resolution localization microscopy with single-photon SPAD imagers

NASA Astrophysics Data System (ADS)

Antolovic, Ivan Michel; Burri, Samuel; Bruschini, Claudio; Hoebe, Ron; Charbon, Edoardo

2016-02-01

For many scientific applications, electron multiplying charge coupled devices (EMCCDs) have been the sensor of choice because of their high quantum efficiency and built-in electron amplification. Lately, many researchers introduced scientific complementary metal-oxide semiconductor (sCMOS) imagers in their instrumentation, so as to take advantage of faster readout and the absence of excess noise. Alternatively, single-photon avalanche diode (SPAD) imagers can provide even faster frame rates and zero readout noise. SwissSPAD is a 1-bit 512×128 SPAD imager, one of the largest of its kind, featuring a frame duration of 6.4 μs. Additionally, a gating mechanism enables photosensitive windows as short as 5 ns with a skew better than 150 ps across the entire array. The SwissSPAD photon detection efficiency (PDE) uniformity is very high, thanks on one side to a photon-to-digital conversion and on the other to a reduced fraction of "hot pixels" or "screamers", which would pollute the image with noise. A low native fill factor was recovered to a large extent using a microlens array, leading to a maximum PDE increase of 12×. This enabled us to detect single fluorophores, as required by ground state depletion followed by individual molecule return imaging microscopy (GSDIM). We show the first super resolution results obtained with a SPAD imager, with an estimated localization uncertainty of 30 nm and resolution of 100 nm. The high time resolution of 6.4 μs can be utilized to explore the dye's photophysics or for dye optimization. We also present the methodology for the blinking analysis on experimental data.

On a fast calculation of structure factors at a subatomic resolution.

PubMed

Afonine, P V; Urzhumtsev, A

2004-01-01

In the last decade, the progress of protein crystallography allowed several protein structures to be solved at a resolution higher than 0.9 A. Such studies provide researchers with important new information reflecting very fine structural details. The signal from these details is very weak with respect to that corresponding to the whole structure. Its analysis requires high-quality data, which previously were available only for crystals of small molecules, and a high accuracy of calculations. The calculation of structure factors using direct formulae, traditional for 'small-molecule' crystallography, allows a relatively simple accuracy control. For macromolecular crystals, diffraction data sets at a subatomic resolution contain hundreds of thousands of reflections, and the number of parameters used to describe the corresponding models may reach the same order. Therefore, the direct way of calculating structure factors becomes very time expensive when applied to large molecules. These problems of high accuracy and computational efficiency require a re-examination of computer tools and algorithms. The calculation of model structure factors through an intermediate generation of an electron density [Sayre (1951). Acta Cryst. 4, 362-367; Ten Eyck (1977). Acta Cryst. A33, 486-492] may be much more computationally efficient, but contains some parameters (grid step, 'effective' atom radii etc.) whose influence on the accuracy of the calculation is not straightforward. At the same time, the choice of parameters within safety margins that largely ensure a sufficient accuracy may result in a significant loss of the CPU time, making it close to the time for the direct-formulae calculations. The impact of the different parameters on the computer efficiency of structure-factor calculation is studied. It is shown that an appropriate choice of these parameters allows the structure factors to be obtained with a high accuracy and in a significantly shorter time than that required when using the direct formulae. Practical algorithms for the optimal choice of the parameters are suggested.

Scheduled Relaxation Jacobi method: Improvements and applications

NASA Astrophysics Data System (ADS)

Adsuara, J. E.; Cordero-Carrión, I.; Cerdá-Durán, P.; Aloy, M. A.

2016-09-01

Elliptic partial differential equations (ePDEs) appear in a wide variety of areas of mathematics, physics and engineering. Typically, ePDEs must be solved numerically, which sets an ever growing demand for efficient and highly parallel algorithms to tackle their computational solution. The Scheduled Relaxation Jacobi (SRJ) is a promising class of methods, atypical for combining simplicity and efficiency, that has been recently introduced for solving linear Poisson-like ePDEs. The SRJ methodology relies on computing the appropriate parameters of a multilevel approach with the goal of minimizing the number of iterations needed to cut down the residuals below specified tolerances. The efficiency in the reduction of the residual increases with the number of levels employed in the algorithm. Applying the original methodology to compute the algorithm parameters with more than 5 levels notably hinders obtaining optimal SRJ schemes, as the mixed (non-linear) algebraic-differential system of equations from which they result becomes notably stiff. Here we present a new methodology for obtaining the parameters of SRJ schemes that overcomes the limitations of the original algorithm and provide parameters for SRJ schemes with up to 15 levels and resolutions of up to 215 points per dimension, allowing for acceleration factors larger than several hundreds with respect to the Jacobi method for typical resolutions and, in some high resolution cases, close to 1000. Most of the success in finding SRJ optimal schemes with more than 10 levels is based on an analytic reduction of the complexity of the previously mentioned system of equations. Furthermore, we extend the original algorithm to apply it to certain systems of non-linear ePDEs.

A Very High Order, Adaptable MESA Implementation for Aeroacoustic Computations

NASA Technical Reports Server (NTRS)

Dydson, Roger W.; Goodrich, John W.

2000-01-01

Since computational efficiency and wave resolution scale with accuracy, the ideal would be infinitely high accuracy for problems with widely varying wavelength scales. Currently, many of the computational aeroacoustics methods are limited to 4th order accurate Runge-Kutta methods in time which limits their resolution and efficiency. However, a new procedure for implementing the Modified Expansion Solution Approximation (MESA) schemes, based upon Hermitian divided differences, is presented which extends the effective accuracy of the MESA schemes to 57th order in space and time when using 128 bit floating point precision. This new approach has the advantages of reducing round-off error, being easy to program. and is more computationally efficient when compared to previous approaches. Its accuracy is limited only by the floating point hardware. The advantages of this new approach are demonstrated by solving the linearized Euler equations in an open bi-periodic domain. A 500th order MESA scheme can now be created in seconds, making these schemes ideally suited for the next generation of high performance 256-bit (double quadruple) or higher precision computers. This ease of creation makes it possible to adapt the algorithm to the mesh in time instead of its converse: this is ideal for resolving varying wavelength scales which occur in noise generation simulations. And finally, the sources of round-off error which effect the very high order methods are examined and remedies provided that effectively increase the accuracy of the MESA schemes while using current computer technology.

Luminous Efficiency Estimates of Meteors. II. Application to Canadian Automated Meteor Observatory Meteor Events

NASA Astrophysics Data System (ADS)

Subasinghe, Dilini; Campbell-Brown, Margaret

2018-02-01

Luminous efficiency is a necessary parameter for determining meteoroid mass from optical emission. Despite this importance, it is very poorly known, with previous results varying by up to two orders of magnitude for a given speed. We present the most recent study of luminous efficiency values determined with modern high-resolution instruments, by directly comparing dynamic and photometric meteoroid masses. Fifteen non-fragmenting meteoroids were used, with a further five clearly fragmenting events for comparison. Twelve of the fifteen non-fragmenting meteoroids had luminous efficiencies less than 1%, while the fragmenting meteoroids had upper limits of a few tens of per cent. No clear trend with speed was seen, but there was a weak negative trend of luminous efficiency on meteoroid mass, implying that smaller meteoroids radiate more efficiently.

AP-MALDI Mass Spectrometry Imaging of Gangliosides Using 2,6-Dihydroxyacetophenone

NASA Astrophysics Data System (ADS)

Jackson, Shelley N.; Muller, Ludovic; Roux, Aurelie; Oktem, Berk; Moskovets, Eugene; Doroshenko, Vladimir M.; Woods, Amina S.

2018-03-01

Matrix-assisted laser/desorption ionization (MALDI) mass spectrometry imaging (MSI) is widely used as a unique tool to record the distribution of a large range of biomolecules in tissues. 2,6-Dihydroxyacetophenone (DHA) matrix has been shown to provide efficient ionization of lipids, especially gangliosides. The major drawback for DHA as it applies to MS imaging is that it sublimes under vacuum (low pressure) at the extended time necessary to complete both high spatial and mass resolution MSI studies of whole organs. To overcome the problem of sublimation, we used an atmospheric pressure (AP)-MALDI source to obtain high spatial resolution images of lipids in the brain using a high mass resolution mass spectrometer. Additionally, the advantages of atmospheric pressure and DHA for imaging gangliosides are highlighted. The imaging of [M-H]- and [M-H2O-H]- mass peaks for GD1 gangliosides showed different distribution, most likely reflecting the different spatial distribution of GD1a and GD1b species in the brain. [Figure not available: see fulltext.

Highly undersampled MR image reconstruction using an improved dual-dictionary learning method with self-adaptive dictionaries.

PubMed

Li, Jiansen; Song, Ying; Zhu, Zhen; Zhao, Jun

2017-05-01

Dual-dictionary learning (Dual-DL) method utilizes both a low-resolution dictionary and a high-resolution dictionary, which are co-trained for sparse coding and image updating, respectively. It can effectively exploit a priori knowledge regarding the typical structures, specific features, and local details of training sets images. The prior knowledge helps to improve the reconstruction quality greatly. This method has been successfully applied in magnetic resonance (MR) image reconstruction. However, it relies heavily on the training sets, and dictionaries are fixed and nonadaptive. In this research, we improve Dual-DL by using self-adaptive dictionaries. The low- and high-resolution dictionaries are updated correspondingly along with the image updating stage to ensure their self-adaptivity. The updated dictionaries incorporate both the prior information of the training sets and the test image directly. Both dictionaries feature improved adaptability. Experimental results demonstrate that the proposed method can efficiently and significantly improve the quality and robustness of MR image reconstruction.

Applications and Innovations for Use of High Definition and High Resolution Digital Motion Imagery in Space Operations

NASA Technical Reports Server (NTRS)

Grubbs, Rodney

2016-01-01

The first live High Definition Television (HDTV) from a spacecraft was in November, 2006, nearly ten years before the 2016 SpaceOps Conference. Much has changed since then. Now, live HDTV from the International Space Station (ISS) is routine. HDTV cameras stream live video views of the Earth from the exterior of the ISS every day on UStream, and HDTV has even flown around the Moon on a Japanese Space Agency spacecraft. A great deal has been learned about the operations applicability of HDTV and high resolution imagery since that first live broadcast. This paper will discuss the current state of real-time and file based HDTV and higher resolution video for space operations. A potential roadmap will be provided for further development and innovations of high-resolution digital motion imagery, including gaps in technology enablers, especially for deep space and unmanned missions. Specific topics to be covered in the paper will include: An update on radiation tolerance and performance of various camera types and sensors and ramifications on the future applicability of these types of cameras for space operations; Practical experience with downlinking very large imagery files with breaks in link coverage; Ramifications of larger camera resolutions like Ultra-High Definition, 6,000 [pixels] and 8,000 [pixels] in space applications; Enabling technologies such as the High Efficiency Video Codec, Bundle Streaming Delay Tolerant Networking, Optical Communications and Bayer Pattern Sensors and other similar innovations; Likely future operations scenarios for deep space missions with extreme latency and intermittent communications links.

Describing litho-constrained layout by a high-resolution model filter

NASA Astrophysics Data System (ADS)

Tsai, Min-Chun

2008-05-01

A novel high-resolution model (HRM) filtering technique was proposed to describe litho-constrained layouts. Litho-constrained layouts are layouts that have difficulties to pattern or are highly sensitive to process-fluctuations under current lithography technologies. HRM applies a short-wavelength (or high NA) model simulation directly on the pre-OPC, original design layout to filter out low spatial-frequency regions, and retain high spatial-frequency components which are litho-constrained. Since no OPC neither mask-synthesis steps are involved, this new technique is highly efficient in run time and can be used in design stage to detect and fix litho-constrained patterns. This method has successfully captured all the hot-spots with less than 15% overshoots on a realistic 80 mm2 full-chip M1 layout in 65nm technology node. A step by step derivation of this HRM technique is presented in this paper.

X-ray diffraction microscopy on frozen hydrated specimens

NASA Astrophysics Data System (ADS)

Nelson, Johanna

X-rays are excellent for imaging thick samples at high resolution because of their large penetration depth compared to electrons and their short wavelength relative to visible light. To image biological material, the absorption contrast of soft X-rays, especially between the carbon and oxygen K-shell absorption edges, can be utilized to give high contrast, high resolution images without the need for stains or labels. Because of radiation damage and the desire for high resolution tomography, live cell imaging is not feasible. However, cells can be frozen in vitrified ice, which reduces the effect of radiation damage while maintaining their natural hydrated state. X-ray diffraction microscopy (XDM) is an imaging technique which eliminates the limitations imposed by current focusing optics simply by removing them entirely. Far-field coherent diffraction intensity patterns are collected on a pixelated detector allowing every scattered photon to be collected within the limits of the detector's efficiency and physical size. An iterative computer algorithm is then used to invert the diffraction intensity into a real space image with both absorption and phase information. This technique transfers the emphasis away from fabrication and alignment of optics, and towards data processing. We have used this method to image a pair of freeze-dried, immuno-labeled yeast cells to the highest resolution (13 nm) yet obtained for a whole eukaryotic cell. We discuss successes and challenges in working with frozen hydrated specimens and efforts aimed at high resolution imaging of vitrified eukaryotic cells in 3D.

Cellular resolution functional imaging in behaving rats using voluntary head restraint

PubMed Central

Scott, Benjamin B.; Brody, Carlos D.; Tank, David W.

2013-01-01

SUMMARY High-throughput operant conditioning systems for rodents provide efficient training on sophisticated behavioral tasks. Combining these systems with technologies for cellular resolution functional imaging would provide a powerful approach to study neural dynamics during behavior. Here we describe an integrated two-photon microscope and behavioral apparatus that allows cellular resolution functional imaging of cortical regions during epochs of voluntary head restraint. Rats were trained to initiate periods of restraint up to 8 seconds in duration, which provided the mechanical stability necessary for in vivo imaging while allowing free movement between behavioral trials. A mechanical registration system repositioned the head to within a few microns, allowing the same neuronal populations to be imaged on each trial. In proof-of-principle experiments, calcium dependent fluorescence transients were recorded from GCaMP-labeled cortical neurons. In contrast to previous methods for head restraint, this system can also be incorporated into high-throughput operant conditioning systems. PMID:24055015

X-ray rocking curve measurements of bent crystals. [used in High Resolution Spectrometer in Advanced X-ray Astrophysics Facility

NASA Technical Reports Server (NTRS)

Hakim, M. B.; Muney, W. S.; Fowler, W. B.; Woodgate, B. E.

1988-01-01

A three-crystal laboratory X-ray spectrometer is used to measure the Bragg reflection from concave cylindrically curved crystals to be used in the high-resolution X-ray spectrometer of the NASA Advanced X-ray Astrophysics Facility (AXAF). The first two crystals, in the dispersive (1.1) arrangement, select a narrow collimated monochromatic beam in the Cu K-alpha(1) line at 1.5 A (8.1 keV), which illuminates the test crystal. The angular centroids of rocking curves measured along the surface provide a measure of the conformity of the crystal to the desired radius of curvature. Individual and combined rocking-curve widths and areas provide a measure of the resolution and efficiency at 1.54 A. The crystals analyzed included LiF(200), PET, and acid phthalates such as TAP.

Neutron emission spectroscopy of DT plasmas at enhanced energy resolution with diamond detectors

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

Giacomelli, L., E-mail: giacomelli@ifp.cnr.it; Tardocchi, M.; Nocente, M.

2016-11-15

This work presents measurements done at the Peking University Van de Graaff neutron source of the response of single crystal synthetic diamond (SD) detectors to quasi-monoenergetic neutrons of 14-20 MeV. The results show an energy resolution of 1% for incoming 20 MeV neutrons, which, together with 1% detection efficiency, opens up to new prospects for fast ion physics studies in high performance nuclear fusion devices such as SD neutron spectrometry of deuterium-tritium plasmas heated by neutral beam injection.

Creep Measurement Video Extensometer

NASA Technical Reports Server (NTRS)

Jaster, Mark; Vickerman, Mary; Padula, Santo, II; Juhas, John

2011-01-01

Understanding material behavior under load is critical to the efficient and accurate design of advanced aircraft and spacecraft. Technologies such as the one disclosed here allow accurate creep measurements to be taken automatically, reducing error. The goal was to develop a non-contact, automated system capable of capturing images that could subsequently be processed to obtain the strain characteristics of these materials during deformation, while maintaining adequate resolution to capture the true deformation response of the material. The measurement system comprises a high-resolution digital camera, computer, and software that work collectively to interpret the image.

Sea Surface Scanner: An advanced catamaran to study the sea surface

NASA Astrophysics Data System (ADS)

Wurl, O.; Mustaffa, N. I. H.; Ribas Ribas, M.

2016-02-01

The Sea Surface Scanner is a remote-controlled catamaran with the capability to sample the sea-surface microlayer in high resolution. The catamaran is equipped with a suite of sensors to scan the sea surface on chemical, biological and physical parameters. Parameters include UV absorption, fluorescence spectra, chlorophyll-a, photosynthetic efficiency, chromophoric dissolved organic matter (CDOM), dissolved oxygen, pH, temperature, and salinity. A further feature is a capability to collect remotely discrete water samples for detailed lab analysis. We present the first high-resolution (< 30 sec) data on the sea surface microlayer. We discuss the variability of biochemical properties of the sea surface and its implication on air-sea interaction.

Compact & Ultra-High Resolution Terahertz Spectroscopic/Fingerprint System

DTIC Science & Technology

2011-05-11

successfully fusion - spliced with commercial silica fibers for the first time, which makes the whole MOPA system monolithic. Fig. 7 (a) shows the output...QPM-GaP crystals and the proposed THz crystal fiber converters for high power parametric THz source, THz waveguide modeling for high efficiency and...THz spectroscopic/fingerprinting system. We have achieved 0.212 mJ fiber laser pulses with transform-limited linewidth, bonded QPM-GaP crystals and

Design of an ultra-thin near-eye display with geometrical waveguide and freeform optics

NASA Astrophysics Data System (ADS)

Tsai, Meng-Che; Lee, Tsung-Xian

2017-02-01

Due to the worldwide portable devices and illumination technology trends, researches interest in laser diodes applications are booming in recent years. One of the popular and potential LDs applications is near-eye display used in VR/AR. An ideal near-eye display needs to provide high resolution, wide FOV imagery with compact magnifying optics, and long battery life for prolonged use. However, previous studies still cannot reach high light utilization efficiency in illumination and imaging optical systems which should be raised as possible to increase wear comfort. To meet these needs, a waveguide illumination system of near-eye display is presented in this paper. We focused on proposing a high efficiency RGB LDs light engine which could reduce power consumption and increase flexibility of mechanism design by using freeform TIR reflectors instead of beam splitters. By these structures, the total system efficiency of near-eye display is successfully increased, and the improved results in efficiency and fabrication tolerance of near-eye displays are shown in this paper.

Mapping soil water content on golf course greens with GPR

USDA-ARS?s Scientific Manuscript database

Ground-penetrating radar (GPR) can be an effective and efficient method for high-resolution mapping of volumetric water content in the sand layer directly beneath the ground surface at a golf course green. This information could potentially be very useful to golf course superintendents for determi...

Efficient multi-objective calibration of a computationally intensive hydrologic model with parallel computing software in Python

USDA-ARS?s Scientific Manuscript database

With enhanced data availability, distributed watershed models for large areas with high spatial and temporal resolution are increasingly used to understand water budgets and examine effects of human activities and climate change/variability on water resources. Developing parallel computing software...

20180311 - EPA’s Non-Targeted Analysis Research Program: Expanding public data resources in support of exposure science (SOT)

EPA Science Inventory

Suspect screening (SSA) and non-targeted analysis (NTA) methods using high-resolution mass spectrometry (HRMS) offer new approaches to efficiently generate exposure data for chemicals in a variety of environmental and biological media. These techniques aid characterization of the...

Enhancing Spatial Resolution of Remotely Sensed Imagery Using Deep Learning

NASA Astrophysics Data System (ADS)

Beck, J. M.; Bridges, S.; Collins, C.; Rushing, J.; Graves, S. J.

2017-12-01

Researchers at the Information Technology and Systems Center at the University of Alabama in Huntsville are using Deep Learning with Convolutional Neural Networks (CNNs) to develop a method for enhancing the spatial resolutions of moderate resolution (10-60m) multispectral satellite imagery. This enhancement will effectively match the resolutions of imagery from multiple sensors to provide increased global temporal-spatial coverage for a variety of Earth science products. Our research is centered on using Deep Learning for automatically generating transformations for increasing the spatial resolution of remotely sensed images with different spatial, spectral, and temporal resolutions. One of the most important steps in using images from multiple sensors is to transform the different image layers into the same spatial resolution, preferably the highest spatial resolution, without compromising the spectral information. Recent advances in Deep Learning have shown that CNNs can be used to effectively and efficiently upscale or enhance the spatial resolution of multispectral images with the use of an auxiliary data source such as a high spatial resolution panchromatic image. In contrast, we are using both the spatial and spectral details inherent in low spatial resolution multispectral images for image enhancement without the use of a panchromatic image. This presentation will discuss how this technology will benefit many Earth Science applications that use remotely sensed images with moderate spatial resolutions.

Diamond Scattering Detectors for Compton Telescopes

NASA Astrophysics Data System (ADS)

Bloser, Peter

The objective of the proposed work is to demonstrate the suitability of artificial singlecrystal diamond detectors (SCDDs) for use as the scattering medium in Compton telescopes for medium-energy gamma-ray astronomy. SCDDs offer the possibility of position and energy resolution comparable to those of silicon solid-state detectors (SSDs), combined with efficiency and timing resolution so-far only achievable using fast scintillators. When integrated with a calorimeter composed of fast inorganic scintillator, such as CeBr3, read out by silicon photomultipliers (SiPMs), SCDDs will enable a compact and efficient Compton telescope using time-of-flight (ToF) discrimination to achieve low background and high sensitivity. This detector development project will be a collaboration between the University of New Hampshire (UNH) and Southwest Research Institute (SwRI). The proposed work represents an innovative combination of detector technologies originally conceived separately for high-energy astronomy (fast scintillators read out by SiPMs; UNH) and space plasma/particle physics (SCDDs; SwRI). Recently SwRI has demonstrated that SCDDs fabricated using chemical vapor deposition (CVD) show good energy resolution ( 7 keV FWHM), comparable to silicon SSDs, with much faster time response ( ns rise time) due to higher electron/hole mobilities. They are also temperature- and lightinsensitive, and radiation hard. In addition, diamond is low-Z, composed entirely of carbon, but relatively high-density (3.5 g cm-3) compared to silicon or organic scintillator. SCDDs are therefore an intriguing possibility for a new Compton scattering element: if patterned with mm-sized readout electrodes and combined with a fast inorganic scintillator calorimeter, SCDDs could enable a compact but efficient Compton telescope with superior angular and energy resolution, while maintaining ToF background rejection. Such an instrument offers the exciting potential for unprecedented sensitivity, especially at energies < 1 - 2 MeV, on a small-scale mission utilizing recently available SmallSat buses (payload mass <100 kg). We propose to demonstrate this by constructing and testing a small proof-of-concept prototype and, based on its performance, using Monte Carlo simulations to explore the possibilities of furthering MeV science using relatively small-scale space missions.

X-ray detection capability of a BaCl{sub 2} single crystal scintillator

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

Koshimizu, Masanori; CREST, Japan Science and Technology Agency, Sanbancho, Chiyoda-ku, Tokyo 102-0075; Onodera, Kazuya

2012-01-15

The x-ray detection capability of a scintillation detector equipped with a BaCl{sub 2} single crystal was evaluated. The scintillation decay kinetics can be expressed by a sum of two exponential decay components. The fast and slow components have lifetimes of 1.5 and 85 ns, respectively. The total light output is 5% that of YAP:Ce. A subnanosecond timing resolution was obtained. The detection efficiency of a 67.41 keV x-ray is 87% for a detector equipped with a BaCl{sub 2} crystal 6-mm thick. Thus, excellent timing resolution and high detection efficiency can be simultaneously achieved. Additionally, luminescence decay characteristics under vacuum ultravioletmore » excitation have been investigated. Radiative decay of self-trapped excitons is thought to be responsible for the fast scintillation component.« less

Efficient demodulation scheme for rolling-shutter-patterning of CMOS image sensor based visible light communications.

PubMed

Chen, Chia-Wei; Chow, Chi-Wai; Liu, Yang; Yeh, Chien-Hung

2017-10-02

Recently even the low-end mobile-phones are equipped with a high-resolution complementary-metal-oxide-semiconductor (CMOS) image sensor. This motivates using a CMOS image sensor for visible light communication (VLC). Here we propose and demonstrate an efficient demodulation scheme to synchronize and demodulate the rolling shutter pattern in image sensor based VLC. The implementation algorithm is discussed. The bit-error-rate (BER) performance and processing latency are evaluated and compared with other thresholding schemes.

Efficient fabrication method of nano-grating for 3D holographic display with full parallax views.

PubMed

Wan, Wenqiang; Qiao, Wen; Huang, Wenbin; Zhu, Ming; Fang, Zongbao; Pu, Donglin; Ye, Yan; Liu, Yanhua; Chen, Linsen

2016-03-21

Without any special glasses, multiview 3D displays based on the diffractive optics can present high resolution, full-parallax 3D images in an ultra-wide viewing angle. The enabling optical component, namely the phase plate, can produce arbitrarily distributed view zones by carefully designing the orientation and the period of each nano-grating pixel. However, such 3D display screen is restricted to a limited size due to the time-consuming fabricating process of nano-gratings on the phase plate. In this paper, we proposed and developed a lithography system that can fabricate the phase plate efficiently. Here we made two phase plates with full nano-grating pixel coverage at a speed of 20 mm²/mins, a 500 fold increment in the efficiency when compared to the method of E-beam lithography. One 2.5-inch phase plate generated 9-view 3D images with horizontal-parallax, while the other 6-inch phase plate produced 64-view 3D images with full-parallax. The angular divergence in horizontal axis and vertical axis was 1.5 degrees, and 1.25 degrees, respectively, slightly larger than the simulated value of 1.2 degrees by Finite Difference Time Domain (FDTD). The intensity variation was less than 10% for each viewpoint, in consistency with the simulation results. On top of each phase plate, a high-resolution binary masking pattern containing amplitude information of all viewing zone was well aligned. We achieved a resolution of 400 pixels/inch and a viewing angle of 40 degrees for 9-view 3D images with horizontal parallax. In another prototype, the resolution of each view was 160 pixels/inch and the view angle was 50 degrees for 64-view 3D images with full parallax. As demonstrated in the experiments, the homemade lithography system provided the key fabricating technology for multiview 3D holographic display.

Monte Carlo simulation of a very high resolution thermal neutron detector composed of glass scintillator microfibers.

PubMed

Song, Yushou; Conner, Joseph; Zhang, Xiaodong; Hayward, Jason P

2016-02-01

In order to develop a high spatial resolution (micron level) thermal neutron detector, a detector assembly composed of cerium doped lithium glass microfibers, each with a diameter of 1 μm, is proposed, where the neutron absorption location is reconstructed from the observed charged particle products that result from neutron absorption. To suppress the cross talk of the scintillation light, each scintillating fiber is surrounded by air-filled glass capillaries with the same diameter as the fiber. This pattern is repeated to form a bulk microfiber detector. On one end, the surface of the detector is painted with a thin optical reflector to increase the light collection efficiency at the other end. Then the scintillation light emitted by any neutron interaction is transmitted to one end, magnified, and recorded by an intensified CCD camera. A simulation based on the Geant4 toolkit was developed to model this detector. All the relevant physics processes including neutron interaction, scintillation, and optical boundary behaviors are simulated. This simulation was first validated through measurements of neutron response from lithium glass cylinders. With good expected light collection, an algorithm based upon the features inherent to alpha and triton particle tracks is proposed to reconstruct the neutron reaction position in the glass fiber array. Given a 1 μm fiber diameter and 0.1mm detector thickness, the neutron spatial resolution is expected to reach σ∼1 μm with a Gaussian fit in each lateral dimension. The detection efficiency was estimated to be 3.7% for a glass fiber assembly with thickness of 0.1mm. When the detector thickness increases from 0.1mm to 1mm, the position resolution is not expected to vary much, while the detection efficiency is expected to increase by about a factor of ten. Copyright © 2015 Elsevier Ltd. All rights reserved.

A high-resolution physically-based global flood hazard map

NASA Astrophysics Data System (ADS)

Kaheil, Y.; Begnudelli, L.; McCollum, J.

2016-12-01

We present the results from a physically-based global flood hazard model. The model uses a physically-based hydrologic model to simulate river discharges, and 2D hydrodynamic model to simulate inundation. The model is set up such that it allows the application of large-scale flood hazard through efficient use of parallel computing. For hydrology, we use the Hillslope River Routing (HRR) model. HRR accounts for surface hydrology using Green-Ampt parameterization. The model is calibrated against observed discharge data from the Global Runoff Data Centre (GRDC) network, among other publicly-available datasets. The parallel-computing framework takes advantage of the river network structure to minimize cross-processor messages, and thus significantly increases computational efficiency. For inundation, we implemented a computationally-efficient 2D finite-volume model with wetting/drying. The approach consists of simulating flood along the river network by forcing the hydraulic model with the streamflow hydrographs simulated by HRR, and scaled up to certain return levels, e.g. 100 years. The model is distributed such that each available processor takes the next simulation. Given an approximate criterion, the simulations are ordered from most-demanding to least-demanding to ensure that all processors finalize almost simultaneously. Upon completing all simulations, the maximum envelope of flood depth is taken to generate the final map. The model is applied globally, with selected results shown from different continents and regions. The maps shown depict flood depth and extent at different return periods. These maps, which are currently available at 3 arc-sec resolution ( 90m) can be made available at higher resolutions where high resolution DEMs are available. The maps can be utilized by flood risk managers at the national, regional, and even local levels to further understand their flood risk exposure, exercise certain measures of mitigation, and/or transfer the residual risk financially through flood insurance programs.

New Detector Developments for Future UV Space Missions

NASA Astrophysics Data System (ADS)

Werner, Klaus; Kappelmann, Norbert

Ultraviolet (UV) astronomy is facing “dark ages”: After the shutdown of the Hubble Space Tele-scope only the WSO/UV mission will be operable in the UV wavelength region with efficient instruments. Improved optics and detectors are necessary for future successor missions to tackle new scientific goals. This drives our development of microchannel plate (MCP) UV-detectors with high quantum efficiency, high spatial resolution and low-power readout electronics. To enhance the quantum efficiency and the lifetime of the MCP detectors we are developing new cathodes and new anodes for these detectors. To achieve high quantum efficiency, we will use caesium-activated gallium nitride as semitransparent photocathodes with a much higher efficiency than default CsI/CsTe cathodes in this wavelength range. The new anodes will be cross-strip anodes with 64 horizontal and 64 vertical electrodes. This type of anode requires a lower gain and leads to an increased lifetime of the detector, compared to MCP detectors with other anode types. The heart of the new developed front-end-electronic for such type of anode is the so called “BEETLE chip”, which was designed by the MPI für Kernphysik Heidelberg for the LHCb ex-periment at CERN. This chip provides 128 input channels with charge-sensitive preamplifiers and shapers. Our design of the complete front-end readout electronics enables a total power con-sumption of less than 10 W. The MCP detector is intrinsically solar blind, single photon counting and has a very low read-out noise. To qualify this new type of detectors we are presently planning to build a small UV telescope for the usage on the German Technology Experimental Carrier (TET). Furthermore we are involved in the new German initiative for a Public Telescope, a space telescope equipped with an 80 cm mirror. One of the main instruments will be a high-resolution UV-Echelle Spectrograph that will be built by the University of Tübingen. The launch of this mission is scheduled for 2017.

Purification of Training Samples Based on Spectral Feature and Superpixel Segmentation

NASA Astrophysics Data System (ADS)

Guan, X.; Qi, W.; He, J.; Wen, Q.; Chen, T.; Wang, Z.

2018-04-01

Remote sensing image classification is an effective way to extract information from large volumes of high-spatial resolution remote sensing images. Generally, supervised image classification relies on abundant and high-precision training data, which is often manually interpreted by human experts to provide ground truth for training and evaluating the performance of the classifier. Remote sensing enterprises accumulated lots of manually interpreted products from early lower-spatial resolution remote sensing images by executing their routine research and business programs. However, these manually interpreted products may not match the very high resolution (VHR) image properly because of different dates or spatial resolution of both data, thus, hindering suitability of manually interpreted products in training classification models, or small coverage area of these manually interpreted products. We also face similar problems in our laboratory in 21st Century Aerospace Technology Co. Ltd (short for 21AT). In this work, we propose a method to purify the interpreted product to match newly available VHRI data and provide the best training data for supervised image classifiers in VHR image classification. And results indicate that our proposed method can efficiently purify the input data for future machine learning use.

Effect of Te inclusions in CdZnTe crystals at different temperatures

NASA Astrophysics Data System (ADS)

Hossain, A.; Bolotnikov, A. E.; Camarda, G. S.; Gul, R.; Kim, K.-H.; Cui, Y.; Yang, G.; Xu, L.; James, R. B.

2011-02-01

CdZnTe crystals often exhibit nonuniformities due to the presence of Te inclusions and dislocations. High concentrations of such defects in these crystals generally entail severe charge-trapping, a major problem in ensuring the device's satisfactory performance. In this study, we employed a high-intensity, high-spatial-resolution synchrotron x-ray beam as the ideal tool to generate charges by focusing it over the large Te inclusions, and then observing the carrier's response at room- and at low-temperatures. A high spatial 5-μm resolution raster scan revealed the fine details of the presence of extended defects, like Te inclusions and dislocations in the CdZnTe crystals. A noticeable change was observed in the efficiency of electron charge collection at low temperature (1 °C), but it was hardly altered at room-temperature.

Getting to the point: Rapid point selection and variable density InSAR time series for urban deformation monitoring

NASA Astrophysics Data System (ADS)

Spaans, K.; Hooper, A. J.

2017-12-01

The short revisit time and high data acquisition rates of current satellites have resulted in increased interest in the development of deformation monitoring and rapid disaster response capability, using InSAR. Fast, efficient data processing methodologies are required to deliver the timely results necessary for this, and also to limit computing resources required to process the large quantities of data being acquired. Contrary to volcano or earthquake applications, urban monitoring requires high resolution processing, in order to differentiate movements between buildings, or between buildings and the surrounding land. Here we present Rapid time series InSAR (RapidSAR), a method that can efficiently update high resolution time series of interferograms, and demonstrate its effectiveness over urban areas. The RapidSAR method estimates the coherence of pixels on an interferogram-by-interferogram basis. This allows for rapid ingestion of newly acquired images without the need to reprocess the earlier acquired part of the time series. The coherence estimate is based on ensembles of neighbouring pixels with similar amplitude behaviour through time, which are identified on an initial set of interferograms, and need be re-evaluated only occasionally. By taking into account scattering properties of points during coherence estimation, a high quality coherence estimate is achieved, allowing point selection at full resolution. The individual point selection maximizes the amount of information that can be extracted from each interferogram, as no selection compromise has to be reached between high and low coherence interferograms. In other words, points do not have to be coherent throughout the time series to contribute to the deformation time series. We demonstrate the effectiveness of our method over urban areas in the UK. We show how the algorithm successfully extracts high density time series from full resolution Sentinel-1 interferograms, and distinguish clearly between buildings and surrounding vegetation or streets. The fact that new interferograms can be processed separately from the remainder of the time series helps manage the high data volumes, both in space and time, generated by current missions.

Fabrication of perforated isoporous membranes via a transfer-free strategy: enabling high-resolution separation of cells.

PubMed

Ou, Yang; Lv, Chang-Jiang; Yu, Wei; Mao, Zheng-Wei; Wan, Ling-Shu; Xu, Zhi-Kang

2014-12-24

Thin perforated membranes with ordered pores are ideal barriers for high-resolution and high-efficiency selective transport and separation of biological species. However, for self-assembled thin membranes with a thickness less than several micrometers, an additional step of transferring the membranes onto porous supports is generally required. In this article, we present a facile transfer-free strategy for fabrication of robust perforated composite membranes via the breath figure process, and for the first time, demonstrate the application of the membranes in high-resolution cell separation of yeasts and lactobacilli without external pressure, achieving almost 100% rejection of yeasts and more than 70% recovery of lactobacilli with excellent viability. The avoidance of the transfer step simplifies the fabrication procedure of composite membranes and greatly improves the membrane homogeneity. Moreover, the introduction of an elastic triblock copolymer increases the interfacial strength between the membrane and the support, and allows the preservation of composite membranes in a dry state. Such perforated ordered membranes can also be applied in other size-based separation systems, enabling new opportunities in bioseparation and biosensors.

Precise Spatiotemporal Control of Optogenetic Activation Using an Acousto-Optic Device

PubMed Central

Guo, Yanmeng; Song, Peipei; Zhang, Xiaohui; Zeng, Shaoqun; Wang, Zuoren

2011-01-01

Light activation and inactivation of neurons by optogenetic techniques has emerged as an important tool for studying neural circuit function. To achieve a high resolution, new methods are being developed to selectively manipulate the activity of individual neurons. Here, we report that the combination of an acousto-optic device (AOD) and single-photon laser was used to achieve rapid and precise spatiotemporal control of light stimulation at multiple points in a neural circuit with millisecond time resolution. The performance of this system in activating ChIEF expressed on HEK 293 cells as well as cultured neurons was first evaluated, and the laser stimulation patterns were optimized. Next, the spatiotemporally selective manipulation of multiple neurons was achieved in a precise manner. Finally, we demonstrated the versatility of this high-resolution method in dissecting neural circuits both in the mouse cortical slice and the Drosophila brain in vivo. Taken together, our results show that the combination of AOD-assisted laser stimulation and optogenetic tools provides a flexible solution for manipulating neuronal activity at high efficiency and with high temporal precision. PMID:22174813

Calorimetric low-temperature detectors for high resolution x-ray spectroscopy on stored highly stripped heavy ions

NASA Astrophysics Data System (ADS)

Bleile, A.; Egelhof, P.; Kraft, S.; McCammon, D.; Meier, H. J.; Shrivastava, A.; Stahle, C. K.; Weber, M.

2002-02-01

The accurate determination of the Lamb shift in heavy hydrogen-like ions provides a sensitive test of quantum electrodynamics in very strong Coulomb fields, not accessible otherwise. For the investigation of the Lyman-α transitions in 208Pb81+ or 238U91+ with sufficient accuracy, a high resolution calorimetric detector for hard x-rays (E<=100 keV) is presently being developed. The detector modules consist of arrays of silicon thermistors and of x-ray absorbers made of high-Z material to optimize the absorption efficiency. The detectors are housed in a specially designed 3He/4He dilution refrigerator with a side arm which fits to the internal target geometry of the storage ring ESR at GSI Darmstadt. The detector performance presently achieved is already close to fulfill the demands of the Lamb shift experiment. For a prototype detector pixel with a 0.2 mm2×47 μm Pb absorber an energy resolution of ΔEFWHM=65 eV is obtained for 60 keV x-rays. .

Towards excimer-laser-based stereolithography: a rapid process to fabricate rigid biodegradable photopolymer scaffolds

PubMed Central

Beke, S.; Anjum, F.; Tsushima, H.; Ceseracciu, L.; Chieregatti, E.; Diaspro, A.; Athanassiou, A.; Brandi, F.

2012-01-01

We demonstrate high-resolution photocross-linking of biodegradable poly(propylene fumarate) (PPF) and diethyl fumarate (DEF) using UV excimer laser photocuring at 308 nm. The curing depth can be tuned in a micrometre range by adjusting the total energy dose (total fluence). Young's moduli of the scaffolds are found to be a few gigapascal, high enough to support bone formation. The results presented here demonstrate that the proposed technique is an excellent tool for the fabrication of stiff and biocompatible structures on a micrometre scale with defined patterns of high resolution in all three spatial dimensions. Using UV laser photocuring at 308 nm will significantly improve the speed of rapid prototyping of biocompatible and biodegradable polymer scaffolds and enables its production in a few seconds, providing high lateral and horizontal resolution. This short timescale is indeed a tremendous asset that will enable a more efficient translation of technology to clinical applications. Preliminary cell tests proved that PPF : DEF scaffolds produced by excimer laser photocuring are biocompatible and, therefore, are promising candidates to be applied in tissue engineering and regenerative medicine. PMID:22696484

High-resolution separation of neodymium and dysprosium ions utilizing extractant-impregnated graft-type particles.

PubMed

Uchiyama, Shoichiro; Sasaki, Takaaki; Ishihara, Ryo; Fujiwara, Kunio; Sugo, Takanobu; Umeno, Daisuke; Saito, Kyoichi

2018-01-19

An efficient method for rare metal recovery from environmental water and urban mines is in high demand. Toward rapid and high-resolution rare metal ion separation, a novel bis(2-ethylhexyl) phosphate (HDEHP)-impregnated graft-type particle as a filler for a chromatography column is proposed. To achieve rapid and high-resolution separation, a convection-flow-aided elution mode is required. The combination of 35 μm non-porous particles and a polymer-brush-rich particle structure minimizes the distance from metal ion binding sites to the convection flow in the column, resulting in minimized diffusional mass transfer resistance and the convection-flow-aided elution mode. The HDEHP-impregnated graft-type non-porous-particle-packed cartridge developed in this study exhibited a higher separation performance for model rare metals, neodymium (III) and dysprosium (III) ions, and a narrower peak at a higher linear velocity, than those of previous HDEHP-impregnated fiber-packed and commercially available Lewatit ® VP OC 1026-packed cartridges. Copyright © 2017 Elsevier B.V. All rights reserved.

Semi-automted analysis of high-resolution aerial images to quantify docks in Upper Midwest glacial lakes

USGS Publications Warehouse

Beck, Marcus W.; Vondracek, Bruce C.; Hatch, Lorin K.; Vinje, Jason

2013-01-01

Lake resources can be negatively affected by environmental stressors originating from multiple sources and different spatial scales. Shoreline development, in particular, can negatively affect lake resources through decline in habitat quality, physical disturbance, and impacts on fisheries. The development of remote sensing techniques that efficiently characterize shoreline development in a regional context could greatly improve management approaches for protecting and restoring lake resources. The goal of this study was to develop an approach using high-resolution aerial photographs to quantify and assess docks as indicators of shoreline development. First, we describe a dock analysis workflow that can be used to quantify the spatial extent of docks using aerial images. Our approach incorporates pixel-based classifiers with object-based techniques to effectively analyze high-resolution digital imagery. Second, we apply the analysis workflow to quantify docks for 4261 lakes managed by the Minnesota Department of Natural Resources. Overall accuracy of the analysis results was 98.4% (87.7% based on ) after manual post-processing. The analysis workflow was also 74% more efficient than the time required for manual digitization of docks. These analyses have immediate relevance for resource planning in Minnesota, whereas the dock analysis workflow could be used to quantify shoreline development in other regions with comparable imagery. These data can also be used to better understand the effects of shoreline development on aquatic resources and to evaluate the effects of shoreline development relative to other stressors.

High-speed and high-resolution quantitative phase imaging with digital-micromirror device-based illumination (Conference Presentation)

NASA Astrophysics Data System (ADS)

Zhou, Renjie; Jin, Di; Yaqoob, Zahid; So, Peter T. C.

2017-02-01

Due to the large number of available mirrors, the patterning speed, low-cost, and compactness, digital-micromirror devices (DMDs) have been extensively used in biomedical imaging system. Recently, DMDs have been brought to the quantitative phase microscopy (QPM) field to achieve synthetic-aperture imaging and tomographic imaging. Last year, our group demonstrated using DMD for QPM, where the phase-retrieval is based on a recently developed Fourier ptychography algorithm. In our previous system, the illumination angle was varied through coding the aperture plane of the illumination system, which has a low efficiency on utilizing the laser power. In our new DMD-based QPM system, we use the Lee-holograms, which is conjugated to the sample plane, to change the illumination angles for much higher power efficiency. Multiple-angle illumination can also be achieved with this method. With this versatile system, we can achieve FPM-based high-resolution phase imaging with 250 nm lateral resolution using the Rayleigh criteria. Due to the use of a powerful laser, the imaging speed would only be limited by the camera acquisition speed. With a fast camera, we expect to achieve close to 100 fps phase imaging speed that has not been achieved in current FPM imaging systems. By adding reference beam, we also expect to achieve synthetic-aperture imaging while directly measuring the phase of the sample fields. This would reduce the phase-retrieval processing time to allow for real-time imaging applications in the future.

The Representation of Tropical Cyclones Within the Global William Putman Non-Hydrostatic Goddard Earth Observing System Model (GEOS-5) at Cloud-Permitting Resolutions

NASA Technical Reports Server (NTRS)

Putman, William M.

2010-01-01

The Goddard Earth Observing System Model (GEOS-S), an earth system model developed in the NASA Global Modeling and Assimilation Office (GMAO), has integrated the non-hydrostatic finite-volume dynamical core on the cubed-sphere grid. The extension to a non-hydrostatic dynamical framework and the quasi-uniform cubed-sphere geometry permits the efficient exploration of global weather and climate modeling at cloud permitting resolutions of 10- to 4-km on today's high performance computing platforms. We have explored a series of incremental increases in global resolution with GEOS-S from irs standard 72-level 27-km resolution (approx.5.5 million cells covering the globe from the surface to 0.1 hPa) down to 3.5-km (approx. 3.6 billion cells).

Structure-aware depth super-resolution using Gaussian mixture model

NASA Astrophysics Data System (ADS)

Kim, Sunok; Oh, Changjae; Kim, Youngjung; Sohn, Kwanghoon

2015-03-01

This paper presents a probabilistic optimization approach to enhance the resolution of a depth map. Conventionally, a high-resolution color image is considered as a cue for depth super-resolution under the assumption that the pixels with similar color likely belong to similar depth. This assumption might induce a texture transferring from the color image into the depth map and an edge blurring artifact to the depth boundaries. In order to alleviate these problems, we propose an efficient depth prior exploiting a Gaussian mixture model in which an estimated depth map is considered to a feature for computing affinity between two pixels. Furthermore, a fixed-point iteration scheme is adopted to address the non-linearity of a constraint derived from the proposed prior. The experimental results show that the proposed method outperforms state-of-the-art methods both quantitatively and qualitatively.

Arrival Metering Precision Study

NASA Technical Reports Server (NTRS)

Prevot, Thomas; Mercer, Joey; Homola, Jeffrey; Hunt, Sarah; Gomez, Ashley; Bienert, Nancy; Omar, Faisal; Kraut, Joshua; Brasil, Connie; Wu, Minghong, G.

2015-01-01

This paper describes the background, method and results of the Arrival Metering Precision Study (AMPS) conducted in the Airspace Operations Laboratory at NASA Ames Research Center in May 2014. The simulation study measured delivery accuracy, flight efficiency, controller workload, and acceptability of time-based metering operations to a meter fix at the terminal area boundary for different resolution levels of metering delay times displayed to the air traffic controllers and different levels of airspeed information made available to the Time-Based Flow Management (TBFM) system computing the delay. The results show that the resolution of the delay countdown timer (DCT) on the controllers display has a significant impact on the delivery accuracy at the meter fix. Using the 10 seconds rounded and 1 minute rounded DCT resolutions resulted in more accurate delivery than 1 minute truncated and were preferred by the controllers. Using the speeds the controllers entered into the fourth line of the data tag to update the delay computation in TBFM in high and low altitude sectors increased air traffic control efficiency and reduced fuel burn for arriving aircraft during time based metering.

Immersion Gratings for Infrared High-resolution Spectroscopy

NASA Astrophysics Data System (ADS)

Sarugaku, Yuki; Ikeda, Yuji; Kobayashi, Naoto; Kaji, Sayumi; Sukegawa, Takashi; Sugiyama, Shigeru; Nakagawa, Takao; Arasaki, Takayuki; Kondo, Sohei; Nakanishi, Kenshi; Yasui, Chikako; Kawakita, Hideyo

2016-10-01

High-resolution spectroscopy in the infrared wavelength range is essential for observations of minor isotopologues, such as HDO for water, and prebiotic organic molecules like hydrocarbons/P-bearing molecules because numerous vibrational molecular bands (including non-polar molecules) are located in this wavelength range. High spectral resolution enables us to detect weak lines without spectral line confusion. This technique has been widely used in planetary sciences, e.g., cometary coma (H2O, CO, and organic molecules), the martian atmosphere (CH4, CO2, H2O and HDO), and the upper atmosphere of gas giants (H3+ and organic molecules such as C2H6). Spectrographs with higher resolution (and higher sensitivity) still have a potential to provide a plenty of findings. However, because the size of spectrographs scales with the spectral resolution, it is difficult to realize it.Immersion grating (IG), which is a diffraction grating wherein the diffraction surface is immersed in a material with a high refractive index (n > 2), provides n times higher spectral resolution compared to a reflective grating of the same size. Because IG reduces the size of spectrograph to 1/n compared to the spectrograph with the same spectral resolution using a conventional reflective grating, it is widely acknowledged as a key optical device to realize compact spectrographs with high spectral resolution.Recently, we succeeded in fabricating a CdZnTe immersion grating with the theoretically predicted diffraction efficiency by machining process using an ultrahigh-precision five-axis processing machine developed by Canon Inc. Using the same technique, we completed a practical germanium (Ge) immersion grating with both a reflection coating on the grating surface and the an AR coating on the entrance surface. It is noteworthy that the wide wavelength range from 2 to 20 um can be covered by the two immersion gratings.In this paper, we present the performances and the applications of the immersion gratings, including the development of a long-NIR (2-5um) high-resolution (R=80,000) spectrograph with Ge-immersion grating, VINROUGE, which is a prototype for the TMT MIR instrument.

Gamma-Ray Focusing Optics for Small Animal Imaging

NASA Technical Reports Server (NTRS)

Pivovaroff, M. J.; Barber, W. C.; Craig, W. W.; Hasegawa, B. H.; Ramsey, B. D.; Taylor, C.

2004-01-01

There is a well-established need for high-resolution radionuclide imaging techniques that provide non-invasive measurement of physiological function in small animals. We, therefore, have begun developing a small animal radionuclide imaging system using grazing incidence mirrors to focus low-energy gamma-rays emitted by I-125, and other radionuclides. Our initial prototype optic, fabricated from thermally-formed glass, demonstrated a resolution of 1500 microns, consistent with the performance predicted by detailed simulations. More recently, we have begun constructing mirrors using a replication technique that reduces low spatial frequency errors in the mirror surface, greatly improving the resolution. Each technique offers particular advantages: e.g., multilayer coatings are easily deposited on glass, while superior resolution is possible with replicated optics. Scaling the results from our prototype optics, which only have a few nested shells, to system where the lens has a full complement of several tens of nested shells, a sensitivity of approx. 1 cps/micro Ci is possible, with the exact number dependent on system magnification and radionuclide species. (Higher levels of efficiency can be obtained with multi-optic imaging systems.) The gamma-ray lens will achieve a resolution as good as 100 microns, independent of the final sensitivity. The combination of high spatial resolution and modest sensitivity will enable in vivo single photon emission imaging studies in small animals.

Real-time and sub-wavelength ultrafast coherent diffraction imaging in the extreme ultraviolet.

PubMed

Zürch, M; Rothhardt, J; Hädrich, S; Demmler, S; Krebs, M; Limpert, J; Tünnermann, A; Guggenmos, A; Kleineberg, U; Spielmann, C

2014-12-08

Coherent Diffraction Imaging is a technique to study matter with nanometer-scale spatial resolution based on coherent illumination of the sample with hard X-ray, soft X-ray or extreme ultraviolet light delivered from synchrotrons or more recently X-ray Free-Electron Lasers. This robust technique simultaneously allows quantitative amplitude and phase contrast imaging. Laser-driven high harmonic generation XUV-sources allow table-top realizations. However, the low conversion efficiency of lab-based sources imposes either a large scale laser system or long exposure times, preventing many applications. Here we present a lensless imaging experiment combining a high numerical aperture (NA = 0.8) setup with a high average power fibre laser driven high harmonic source. The high flux and narrow-band harmonic line at 33.2 nm enables either sub-wavelength spatial resolution close to the Abbe limit (Δr = 0.8λ) for long exposure time, or sub-70 nm imaging in less than one second. The unprecedented high spatial resolution, compactness of the setup together with the real-time capability paves the way for a plethora of applications in fundamental and life sciences.

A new variable-resolution associative memory for high energy physics

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

Annovi, A.; Amerio, S.; Beretta, M.

2011-07-01

We describe an important advancement for the Associative Memory device (AM). The AM is a VLSI processor for pattern recognition based on Content Addressable Memory (CAM) architecture. The AM is optimized for on-line track finding in high-energy physics experiments. Pattern matching is carried out by finding track candidates in coarse resolution 'roads'. A large AM bank stores all trajectories of interest, called 'patterns', for a given detector resolution. The AM extracts roads compatible with a given event during detector read-out. Two important variables characterize the quality of the AM bank: its 'coverage' and the level of fake roads. The coverage,more » which describes the geometric efficiency of a bank, is defined as the fraction of tracks that match at least one pattern in the bank. Given a certain road size, the coverage of the bank can be increased just adding patterns to the bank, while the number of fakes unfortunately is roughly proportional to the number of patterns in the bank. Moreover, as the luminosity increases, the fake rate increases rapidly because of the increased silicon occupancy. To counter that, we must reduce the width of our roads. If we decrease the road width using the current technology, the system will become very large and extremely expensive. We propose an elegant solution to this problem: the 'variable resolution patterns'. Each pattern and each detector layer within a pattern will be able to use the optimal width, but we will use a 'don't care' feature (inspired from ternary CAMs) to increase the width when that is more appropriate. In other words we can use patterns of variable shape. As a result we reduce the number of fake roads, while keeping the efficiency high and avoiding excessive bank size due to the reduced width. We describe the idea, the implementation in the new AM design and the implementation of the algorithm in the simulation. Finally we show the effectiveness of the 'variable resolution patterns' idea using simulated high occupancy events in the ATLAS detector. (authors)« less

Evaluating a Local Ensemble Transform Kalman Filter snow cover data assimilation method to estimate SWE within a high-resolution hydrologic modeling framework across Western US mountainous regions

NASA Astrophysics Data System (ADS)

Oaida, C. M.; Andreadis, K.; Reager, J. T., II; Famiglietti, J. S.; Levoe, S.

2017-12-01

Accurately estimating how much snow water equivalent (SWE) is stored in mountainous regions characterized by complex terrain and snowmelt-driven hydrologic cycles is not only greatly desirable, but also a big challenge. Mountain snowpack exhibits high spatial variability across a broad range of spatial and temporal scales due to a multitude of physical and climatic factors, making it difficult to observe or estimate in its entirety. Combing remotely sensed data and high resolution hydrologic modeling through data assimilation (DA) has the potential to provide a spatially and temporally continuous SWE dataset at horizontal scales that capture sub-grid snow spatial variability and are also relevant to stakeholders such as water resource managers. Here, we present the evaluation of a new snow DA approach that uses a Local Ensemble Transform Kalman Filter (LETKF) in tandem with the Variable Infiltration Capacity macro-scale hydrologic model across the Western United States, at a daily temporal resolution, and a horizontal resolution of 1.75 km x 1.75 km. The LETKF is chosen for its relative simplicity, ease of implementation, and computational efficiency and scalability. The modeling/DA system assimilates daily MODIS Snow Covered Area and Grain Size (MODSCAG) fractional snow cover over, and has been developed to efficiently calculate SWE estimates over extended periods of time and covering large regional-scale areas at relatively high spatial resolution, ultimately producing a snow reanalysis-type dataset. Here we focus on the assessment of SWE produced by the DA scheme over several basins in California's Sierra Nevada Mountain range where Airborne Snow Observatory data is available, during the last five water years (2013-2017), which include both one of the driest and one of the wettest years. Comparison against such a spatially distributed SWE observational product provides a greater understanding of the model's ability to estimate SWE and SWE spatial variability, and highlights under which conditions snow cover DA can add value in estimating SWE.

Energy correlations of photon pairs generated by a silicon microring resonator probed by Stimulated Four Wave Mixing.

PubMed

Grassani, Davide; Simbula, Angelica; Pirotta, Stefano; Galli, Matteo; Menotti, Matteo; Harris, Nicholas C; Baehr-Jones, Tom; Hochberg, Michael; Galland, Christophe; Liscidini, Marco; Bajoni, Daniele

2016-04-01

Compact silicon integrated devices, such as micro-ring resonators, have recently been demonstrated as efficient sources of quantum correlated photon pairs. The mass production of integrated devices demands the implementation of fast and reliable techniques to monitor the device performances. In the case of time-energy correlations, this is particularly challenging, as it requires high spectral resolution that is not currently achievable in coincidence measurements. Here we reconstruct the joint spectral density of photons pairs generated by spontaneous four-wave mixing in a silicon ring resonator by studying the corresponding stimulated process, namely stimulated four wave mixing. We show that this approach, featuring high spectral resolution and short measurement times, allows one to discriminate between nearly-uncorrelated and highly-correlated photon pairs.

Microwave sensing technology issues related to a global change technology architecture trade study

NASA Technical Reports Server (NTRS)

Campbell, Thomas G.; Shiue, Jim; Connolly, Denis; Woo, Ken

1991-01-01

The objectives are to enable the development of lighter and less power consuming, high resolution microwave sensors which will operate at frequencies from 1 to 200 GHz. These systems will use large aperture antenna systems (both reflector and phased arrays) capable of wide scan angle, high polarization purity, and utilize sidelobe suppression techniques as required. Essentially, the success of this technology program will enable high resolution microwave radiometers from geostationary orbit, lightweight and more efficient radar systems from low Earth orbit, and eliminate mechanical scanning methods to the fullest extent possible; a main source of platform instability in large space systems. The Global Change Technology Initiative (GCTI) will develop technology which will enable the use of satellite systems for Earth observations on a global scale.

Liborg: a lidar-based robot for efficient 3D mapping

NASA Astrophysics Data System (ADS)

Vlaminck, Michiel; Luong, Hiep; Philips, Wilfried

2017-09-01

In this work we present Liborg, a spatial mapping and localization system that is able to acquire 3D models on the y using data originated from lidar sensors. The novelty of this work is in the highly efficient way we deal with the tremendous amount of data to guarantee fast execution times while preserving sufficiently high accuracy. The proposed solution is based on a multi-resolution technique based on octrees. The paper discusses and evaluates the main benefits of our approach including its efficiency regarding building and updating the map and its compactness regarding compressing the map. In addition, the paper presents a working prototype consisting of a robot equipped with a Velodyne Lidar Puck (VLP-16) and controlled by a Raspberry Pi serving as an independent acquisition platform.

CFD Analysis and Design Optimization Using Parallel Computers

NASA Technical Reports Server (NTRS)

Martinelli, Luigi; Alonso, Juan Jose; Jameson, Antony; Reuther, James

1997-01-01

A versatile and efficient multi-block method is presented for the simulation of both steady and unsteady flow, as well as aerodynamic design optimization of complete aircraft configurations. The compressible Euler and Reynolds Averaged Navier-Stokes (RANS) equations are discretized using a high resolution scheme on body-fitted structured meshes. An efficient multigrid implicit scheme is implemented for time-accurate flow calculations. Optimum aerodynamic shape design is achieved at very low cost using an adjoint formulation. The method is implemented on parallel computing systems using the MPI message passing interface standard to ensure portability. The results demonstrate that, by combining highly efficient algorithms with parallel computing, it is possible to perform detailed steady and unsteady analysis as well as automatic design for complex configurations using the present generation of parallel computers.

High efficiency processing for reduced amplitude zones detection in the HRECG signal

NASA Astrophysics Data System (ADS)

Dugarte, N.; Álvarez, A.; Balacco, J.; Mercado, G.; Gonzalez, A.; Dugarte, E.; Olivares, A.

2016-04-01

Summary - This article presents part of a more detailed research proposed in the medium to long term, with the intention of establishing a new philosophy of electrocardiogram surface analysis. This research aims to find indicators of cardiovascular disease in its early stage that may go unnoticed with conventional electrocardiography. This paper reports the development of a software processing which collect some existing techniques and incorporates novel methods for detection of reduced amplitude zones (RAZ) in high resolution electrocardiographic signal (HRECG).The algorithm consists of three stages, an efficient processing for QRS detection, averaging filter using correlation techniques and a step for RAZ detecting. Preliminary results show the efficiency of system and point to incorporation of techniques new using signal analysis with involving 12 leads.

Room temperature X- and gamma-ray detectors using thallium bromide crystals

NASA Astrophysics Data System (ADS)

Hitomi, K.; Muroi, O.; Shoji, T.; Suehiro, T.; Hiratate, Y.

1999-10-01

Thallium bromide (TlBr) is a compound semiconductor with wide band gap (2.68eV) and high X- and γ-ray stopping power. The TlBr crystals were grown by the horizontal travelling molten zone (TMZ) method using purified material. Two types of room temperature X- and γ-ray detectors were fabricated from the TlBr crystals: TlBr detectors with high detection efficiency for positron annihilation γ-ray (511keV) detection and TlBr detectors with high-energy resolution for low-energy X-ray detection. The detector of the former type demonstrated energy resolution of 56keV FWHM (11%) for 511keV γ-rays. Energy resolution of 1.81keV FWHM for 5.9keV was obtained from the detector of the latter type. In order to analyze noise characteristics of the detector-preamplifier assembly, the equivalent noise charge (ENC) was measured as a function of the amplifier shaping time for the high-resolution detector. This analysis shows that parallel white noise and /1/f noise were dominant noise sources in the detector system. Current-voltage characteristics of the TlBr detector with a small Peltier cooler were also measured. Significant reduction of the detector leakage current was observed for the cooled detectors.

Time-efficient high-resolution whole-brain three-dimensional macromolecular proton fraction mapping

PubMed Central

Yarnykh, Vasily L.

2015-01-01

Purpose Macromolecular proton fraction (MPF) mapping is a quantitative MRI method that reconstructs parametric maps of a relative amount of macromolecular protons causing the magnetization transfer (MT) effect and provides a biomarker of myelination in neural tissues. This study aimed to develop a high-resolution whole-brain MPF mapping technique utilizing a minimal possible number of source images for scan time reduction. Methods The described technique is based on replacement of an actually acquired reference image without MT saturation by a synthetic one reconstructed from R1 and proton density maps, thus requiring only three source images. This approach enabled whole-brain three-dimensional MPF mapping with isotropic 1.25×1.25×1.25 mm3 voxel size and scan time of 20 minutes. The synthetic reference method was validated against standard MPF mapping with acquired reference images based on data from 8 healthy subjects. Results Mean MPF values in segmented white and gray matter appeared in close agreement with no significant bias and small within-subject coefficients of variation (<2%). High-resolution MPF maps demonstrated sharp white-gray matter contrast and clear visualization of anatomical details including gray matter structures with high iron content. Conclusions Synthetic reference method improves resolution of MPF mapping and combines accurate MPF measurements with unique neuroanatomical contrast features. PMID:26102097

Pollen structure visualization using high-resolution laboratory-based hard X-ray tomography

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

Li, Qiong; Gluch, Jürgen; Krüger, Peter

A laboratory-based X-ray microscope is used to investigate the 3D structure of unstained whole pollen grains. For the first time, high-resolution laboratory-based hard X-ray microscopy is applied to study pollen grains. Based on the efficient acquisition of statistically relevant information-rich images using Zernike phase contrast, both surface- and internal structures of pine pollen - including exine, intine and cellular structures - are clearly visualized. The specific volumes of these structures are calculated from the tomographic data. The systematic three-dimensional study of pollen grains provides morphological and structural information about taxonomic characters that are essential in palynology. Such studies have amore » direct impact on disciplines such as forestry, agriculture, horticulture, plant breeding and biodiversity. - Highlights: • The unstained whole pine pollen was visualized by high-resolution laboratory-based HXRM for the first time. • The comparison study of pollen grains by LM, SEM and high-resolution laboratory-based HXRM. • Phase contrast imaging provides significantly higher contrast of the raw images compared to absorption contrast imaging. • Surface and internal structure of the pine pollen including exine, intine and cellular structures are clearly visualized. • 3D volume data of unstained whole pollen grains are acquired and the specific volumes of the different layer are calculated.« less

Low-temperature high-Z gamma-detectors with very high energy resolution

NASA Astrophysics Data System (ADS)

Pobes, Carlos; Brofferio, Chiara; Bucci, Carlo; Cremonesi, Oliviero; Fiorini, Ettore; Giuliani, Andrea; Nucciotti, Angelo; Pavan, Maura; Pedretti, Marisa; Pessina, Gianluigi; Pirro, Stefano; Previtali, Ezio; Sisti, Monica; Vanzini, Marco; Zanotti, Luigi

2001-12-01

High-Z low-temperature calorimeters are developed by an Italian collaboration (Milano-Como-Gran Sasso Underground Laboratories) in order to search for rare nuclear events and Dark Matter massive candidates. They exhibit an excellent energy resolution, close to that of Ge-diodes, but a much higher efficiency. Different high-Z materials were initially employed . A many-years optimisation work on tellurium oxide (TeO2) lead to impressive results: devices with total masses around 750 g present FWHM energy resolutions on gamma-ray peaks ranging from 1 KeV (close to the 5 KeV energy threshold) to 2.6 KeV at 2615 KeV (208Tl gamma line). A 3.2 KeV FWHM energy resolution was obtained at 5.4 MeV (210Po alpha line), which is by far the best one ever achieved with any alpha detector. These devices, operated at about 10 mK, consist of a TeO2 single crystal thermally coupled to a 50 mg Neutron Transmutation Doped (NTD) Ge crystal working as a temperature sensor. Special care was devoted to methods for response linearization and temporal stabilisation. Devices based on the same principle and specifically optimised could find applications in several fields like gamma-ray astrophysics, nuclear physics searches, environmental monitoring and radiation metrology.

Efficient space-time sampling with pixel-wise coded exposure for high-speed imaging.

PubMed

Liu, Dengyu; Gu, Jinwei; Hitomi, Yasunobu; Gupta, Mohit; Mitsunaga, Tomoo; Nayar, Shree K

2014-02-01

Cameras face a fundamental trade-off between spatial and temporal resolution. Digital still cameras can capture images with high spatial resolution, but most high-speed video cameras have relatively low spatial resolution. It is hard to overcome this trade-off without incurring a significant increase in hardware costs. In this paper, we propose techniques for sampling, representing, and reconstructing the space-time volume to overcome this trade-off. Our approach has two important distinctions compared to previous works: 1) We achieve sparse representation of videos by learning an overcomplete dictionary on video patches, and 2) we adhere to practical hardware constraints on sampling schemes imposed by architectures of current image sensors, which means that our sampling function can be implemented on CMOS image sensors with modified control units in the future. We evaluate components of our approach, sampling function and sparse representation, by comparing them to several existing approaches. We also implement a prototype imaging system with pixel-wise coded exposure control using a liquid crystal on silicon device. System characteristics such as field of view and modulation transfer function are evaluated for our imaging system. Both simulations and experiments on a wide range of scenes show that our method can effectively reconstruct a video from a single coded image while maintaining high spatial resolution.

DeMix Workflow for Efficient Identification of Cofragmented Peptides in High Resolution Data-dependent Tandem Mass Spectrometry*

PubMed Central

Zhang, Bo; Pirmoradian, Mohammad; Chernobrovkin, Alexey; Zubarev, Roman A.

2014-01-01

Based on conventional data-dependent acquisition strategy of shotgun proteomics, we present a new workflow DeMix, which significantly increases the efficiency of peptide identification for in-depth shotgun analysis of complex proteomes. Capitalizing on the high resolution and mass accuracy of Orbitrap-based tandem mass spectrometry, we developed a simple deconvolution method of “cloning” chimeric tandem spectra for cofragmented peptides. Additional to a database search, a simple rescoring scheme utilizes mass accuracy and converts the unwanted cofragmenting events into a surprising advantage of multiplexing. With the combination of cloning and rescoring, we obtained on average nine peptide-spectrum matches per second on a Q-Exactive workbench, whereas the actual MS/MS acquisition rate was close to seven spectra per second. This efficiency boost to 1.24 identified peptides per MS/MS spectrum enabled analysis of over 5000 human proteins in single-dimensional LC-MS/MS shotgun experiments with an only two-hour gradient. These findings suggest a change in the dominant “one MS/MS spectrum - one peptide” paradigm for data acquisition and analysis in shotgun data-dependent proteomics. DeMix also demonstrated higher robustness than conventional approaches in terms of lower variation among the results of consecutive LC-MS/MS runs. PMID:25100859

Applications of High-Resolution Electrospray Ionization Mass Spectrometry to Measurements of Average Oxygen to Carbon Ratios in Secondary Organic Aerosols

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

Bateman, Adam P.; Laskin, Julia; Laskin, Alexander

2012-07-02

The applicability of high resolution electrospray ionization mass spectrometry (HR ESI-MS) to measurements of the average oxygen to carbon ratio (O/C) in organic aerosols was investigated. Solutions with known average O/C containing up to 10 standard compounds representative of secondary organic aerosol (SOA) were analyzed and corresponding electrospray ionization efficiencies were quantified. The assumption of equal ionization efficiency commonly used in estimating O/C ratios of organic aerosols was found to be reasonably accurate. We found that the accuracy of the measured O/C ratios increases by averaging the values obtained from both (+) and (-) modes. A correlation was found betweenmore » the ratio of the ionization efficiencies in the positive and negative ESI modes with the octanol-water partition constant, and more importantly, with the compound's O/C. To demonstrate the utility of this correlation for estimating average O/C values of unknown mixtures, we analyzed the ESI (+) and ESI (-) data for SOA produced by oxidation of limonene and isoprene and compared to online O/C measurements using an aerosol mass spectrometer (AMS). This work demonstrates that the accuracy of the HR ESI-MS methods is comparable to that of the AMS, with the added benefit of molecular identification of the aerosol constituents.« less

High resolution PET breast imager with improved detection efficiency

DOEpatents

Majewski, Stanislaw

2010-06-08

A highly efficient PET breast imager for detecting lesions in the entire breast including those located close to the patient's chest wall. The breast imager includes a ring of imaging modules surrounding the imaged breast. Each imaging module includes a slant imaging light guide inserted between a gamma radiation sensor and a photodetector. The slant light guide permits the gamma radiation sensors to be placed in close proximity to the skin of the chest wall thereby extending the sensitive region of the imager to the base of the breast. Several types of photodetectors are proposed for use in the detector modules, with compact silicon photomultipliers as the preferred choice, due to its high compactness. The geometry of the detector heads and the arrangement of the detector ring significantly reduce dead regions thereby improving detection efficiency for lesions located close to the chest wall.

Efficiency droop suppression of distance-engineered surface plasmon-coupled photoluminescence in GaN-based quantum well LEDs

NASA Astrophysics Data System (ADS)

Li, Yufeng; Wang, Shuai; Su, Xilin; Tang, Weihan; Li, Qiang; Guo, Maofeng; Zhang, Ye; Zhang, Minyan; Yun, Feng; Hou, Xun

2017-11-01

Ag coated microgroove with extreme large aspect-ratio of 500:1 was fabricated on p-GaN capping layer to investigate the coupling behavior between quantum wells and surface plasmon in highly spatial resolution. Significant photoluminescence enhancement was observed when the distance between Ag film and QWs was reduced from 220 nm to about 20 nm. A maximum enhancement ratio of 18-fold was achieved at the groove bottom where the surface plasmonic coupling was considered the strongest. Such enhancement ratio was found highly affected by the excitation power density. It also shows high correlation to the internal quantum efficiency as a function of coupling effect and a maximum Purcell Factor of 1.75 was estimated at maximum coupling effect, which matches number calculated independently from the time-resolved photoluminescence measurement. With such Purcell Factor, the efficiency was greatly enhanced and the droop was significantly suppressed.

Development of a hybrid 3-D hydrological model to simulate hillslopes and the regional unconfined aquifer system in Earth system models

NASA Astrophysics Data System (ADS)

Hazenberg, P.; Broxton, P. D.; Brunke, M.; Gochis, D.; Niu, G. Y.; Pelletier, J. D.; Troch, P. A. A.; Zeng, X.

2015-12-01

The terrestrial hydrological system, including surface and subsurface water, is an essential component of the Earth's climate system. Over the past few decades, land surface modelers have built one-dimensional (1D) models resolving the vertical flow of water through the soil column for use in Earth system models (ESMs). These models generally have a relatively coarse model grid size (~25-100 km) and only account for sub-grid lateral hydrological variations using simple parameterization schemes. At the same time, hydrologists have developed detailed high-resolution (~0.1-10 km grid size) three dimensional (3D) models and showed the importance of accounting for the vertical and lateral redistribution of surface and subsurface water on soil moisture, the surface energy balance and ecosystem dynamics on these smaller scales. However, computational constraints have limited the implementation of the high-resolution models for continental and global scale applications. The current work presents a hybrid-3D hydrological approach is presented, where the 1D vertical soil column model (available in many ESMs) is coupled with a high-resolution lateral flow model (h2D) to simulate subsurface flow and overland flow. H2D accounts for both local-scale hillslope and regional-scale unconfined aquifer responses (i.e. riparian zone and wetlands). This approach was shown to give comparable results as those obtained by an explicit 3D Richards model for the subsurface, but improves runtime efficiency considerably. The h3D approach is implemented for the Delaware river basin, where Noah-MP land surface model (LSM) is used to calculated vertical energy and water exchanges with the atmosphere using a 10km grid resolution. Noah-MP was coupled within the WRF-Hydro infrastructure with the lateral 1km grid resolution h2D model, for which the average depth-to-bedrock, hillslope width function and soil parameters were estimated from digital datasets. The ability of this h3D approach to simulate the hydrological dynamics of the Delaware River basin will be assessed by comparing the model results (both hydrological performance and numerical efficiency) with the standard setup of the NOAH-MP model and a high-resolution (1km) version of NOAH-MP, which also explicitly accounts for lateral subsurface and overland flow.

Progress toward accurate high spatial resolution actinide analysis by EPMA

NASA Astrophysics Data System (ADS)

Jercinovic, M. J.; Allaz, J. M.; Williams, M. L.

2010-12-01

High precision, high spatial resolution EPMA of actinides is a significant issue for geochronology, resource geochemistry, and studies involving the nuclear fuel cycle. Particular interest focuses on understanding of the behavior of Th and U in the growth and breakdown reactions relevant to actinide-bearing phases (monazite, zircon, thorite, allanite, etc.), and geochemical fractionation processes involving Th and U in fluid interactions. Unfortunately, the measurement of minor and trace concentrations of U in the presence of major concentrations of Th and/or REEs is particularly problematic, especially in complexly zoned phases with large compositional variation on the micro or nanoscale - spatial resolutions now accessible with modern instruments. Sub-micron, high precision compositional analysis of minor components is feasible in very high Z phases where scattering is limited at lower kV (15kV or less) and where the beam diameter can be kept below 400nm at high current (e.g. 200-500nA). High collection efficiency spectrometers and high performance electron optics in EPMA now allow the use of lower overvoltage through an exceptional range in beam current, facilitating higher spatial resolution quantitative analysis. The U LIII edge at 17.2 kV precludes L-series analysis at low kV (high spatial resolution), requiring careful measurements of the actinide M series. Also, U-La detection (wavelength = 0.9A) requires the use of LiF (220) or (420), not generally available on most instruments. Strong peak overlaps of Th on U make highly accurate interference correction mandatory, with problems compounded by the ThMIV and ThMV absorption edges affecting peak, background, and interference calibration measurements (especially the interference of the Th M line family on UMb). Complex REE bearing phases such as monazite, zircon, and allanite have particularly complex interference issues due to multiple peak and background overlaps from elements present in the activation volume, as well as interferences from fluorescence at a distance from adjacent phases or distinct compositional domains in the same phase. Interference corrections for elements detected during boundary fluorescence are further complicated by X-ray focusing geometry considerations. Additional complications arise from the high current densities required for high spatial resolution and high count precision, such as fluctuations in internal charge distribution and peak shape changes as satellite production efficiency varies from calibration to analysis. No flawless method has yet emerged. Extreme care in interference corrections, especially where multiple and sometime mutual overlaps are present, and maximum care (and precision) in background characterization to account for interferences and curvature (e.g., WDS scan or multipoint regression), are crucial developments. Calibration curves from multiple peak and interference calibration measurements at different concentrations, and iterative software methodologies for incorporating absorption edge effects, and non-linearities in interference corrections due to peak shape changes and off-axis X-ray defocussing during boundary fluorescence at a distance, are directions with significant potential.

Development of High Resolution Mirrors and Cd-Zn-Te Detectors for Hard X-ray Astronomy

NASA Technical Reports Server (NTRS)

Ramsey, Brian D.; Speegle, Chet O.; Gaskin, Jessica; Sharma, Dharma; Engelhaupt, Darell; Six, N. Frank (Technical Monitor)

2002-01-01

We describe the fabrication and implementation of a high-resolution conical, grazing- incidence, hard X-ray (20-70 keV) telescope. When flown aboard stratospheric balloons, these mirrors are used to image cosmic sources such as supernovae, neutron stars, and quasars. The fabrication process involves generating super-polished mandrels, mirror shell electroforming, and mirror testing. The cylindrical mandrels consist of two conical segments; each segment is approximately 305 mm long. These mandrels are first, precision ground to within approx. 1.0 micron straightness along each conical segment and then lapped and polished to less than 0.5 micron straightness. Each mandrel segment is the super-polished to an average surface roughness of approx. 3.25 angstrom rms. By mirror shell replication, this combination of good figure and low surface roughness has enabled us to achieve 15 arcsec, confirmed by X-ray measurements in the Marshall Space Flight Center 102 meter test facility. To image the focused X-rays requires a focal plane detector with appropriate spatial resolution. For 15 arcsec optics of 6 meter focal length, this resolution must be around 200 microns. In addition, the detector must have a high efficiency, relatively high energy resolution, and low background. We are currently developing Cadmium-Zinc-Telluride fine-pixel detectors for this purpose. The detectors under study consist of a 16x16 pixel array with a pixel pitch of 300 microns and are 1 mm and 2 mm thick. At 60 keV, the measured energy resolution is around 2%.

Robust Hydrological Forecasting for High-resolution Distributed Models Using a Unified Data Assimilation Approach

NASA Astrophysics Data System (ADS)

Hernandez, F.; Liang, X.

2017-12-01

Reliable real-time hydrological forecasting, to predict important phenomena such as floods, is invaluable to the society. However, modern high-resolution distributed models have faced challenges when dealing with uncertainties that are caused by the large number of parameters and initial state estimations involved. Therefore, to rely on these high-resolution models for critical real-time forecast applications, considerable improvements on the parameter and initial state estimation techniques must be made. In this work we present a unified data assimilation algorithm called Optimized PareTo Inverse Modeling through Inverse STochastic Search (OPTIMISTS) to deal with the challenge of having robust flood forecasting for high-resolution distributed models. This new algorithm combines the advantages of particle filters and variational methods in a unique way to overcome their individual weaknesses. The analysis of candidate particles compares model results with observations in a flexible time frame, and a multi-objective approach is proposed which attempts to simultaneously minimize differences with the observations and departures from the background states by using both Bayesian sampling and non-convex evolutionary optimization. Moreover, the resulting Pareto front is given a probabilistic interpretation through kernel density estimation to create a non-Gaussian distribution of the states. OPTIMISTS was tested on a low-resolution distributed land surface model using VIC (Variable Infiltration Capacity) and on a high-resolution distributed hydrological model using the DHSVM (Distributed Hydrology Soil Vegetation Model). In the tests streamflow observations are assimilated. OPTIMISTS was also compared with a traditional particle filter and a variational method. Results show that our method can reliably produce adequate forecasts and that it is able to outperform those resulting from assimilating the observations using a particle filter or an evolutionary 4D variational method alone. In addition, our method is shown to be efficient in tackling high-resolution applications with robust results.

Microsecond resolved single-molecule FRET time series measurements based on the line confocal optical system combined with hybrid photodetectors.

PubMed

Oikawa, Hiroyuki; Takahashi, Takumi; Kamonprasertsuk, Supawich; Takahashi, Satoshi

2018-01-31

Single-molecule (sm) fluorescence time series measurements based on the line confocal optical system are a powerful strategy for the investigation of the structure, dynamics, and heterogeneity of biological macromolecules. This method enables the detection of more than several thousands of fluorescence photons per millisecond from single fluorophores, implying that the potential time resolution for measurements of the fluorescence resonance energy transfer (FRET) efficiency is 10 μs. However, the necessity of using imaging photodetectors in the method limits the time resolution in the FRET efficiency measurements to approximately 100 μs. In this investigation, a new photodetector called a hybrid photodetector (HPD) was incorporated into the line confocal system to improve the time resolution without sacrificing the length of the time series detection. Among several settings examined, the system based on a slit width of 10 μm and a high-speed counting device made the best of the features of the line confocal optical system and the HPD. This method achieved a time resolution of 10 μs and an observation time of approximately 5 ms in the sm-FRET time series measurements. The developed device was used for the native state of the B domain of protein A.

Addressing capability computing challenges of high-resolution global climate modelling at the Oak Ridge Leadership Computing Facility

NASA Astrophysics Data System (ADS)

Anantharaj, Valentine; Norman, Matthew; Evans, Katherine; Taylor, Mark; Worley, Patrick; Hack, James; Mayer, Benjamin

2014-05-01

During 2013, high-resolution climate model simulations accounted for over 100 million "core hours" using Titan at the Oak Ridge Leadership Computing Facility (OLCF). The suite of climate modeling experiments, primarily using the Community Earth System Model (CESM) at nearly 0.25 degree horizontal resolution, generated over a petabyte of data and nearly 100,000 files, ranging in sizes from 20 MB to over 100 GB. Effective utilization of leadership class resources requires careful planning and preparation. The application software, such as CESM, need to be ported, optimized and benchmarked for the target platform in order to meet the computational readiness requirements. The model configuration needs to be "tuned and balanced" for the experiments. This can be a complicated and resource intensive process, especially for high-resolution configurations using complex physics. The volume of I/O also increases with resolution; and new strategies may be required to manage I/O especially for large checkpoint and restart files that may require more frequent output for resiliency. It is also essential to monitor the application performance during the course of the simulation exercises. Finally, the large volume of data needs to be analyzed to derive the scientific results; and appropriate data and information delivered to the stakeholders. Titan is currently the largest supercomputer available for open science. The computational resources, in terms of "titan core hours" are allocated primarily via the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) and ASCR Leadership Computing Challenge (ALCC) programs, both sponsored by the U.S. Department of Energy (DOE) Office of Science. Titan is a Cray XK7 system, capable of a theoretical peak performance of over 27 PFlop/s, consists of 18,688 compute nodes, with a NVIDIA Kepler K20 GPU and a 16-core AMD Opteron CPU in every node, for a total of 299,008 Opteron cores and 18,688 GPUs offering a cumulative 560,640 equivalent cores. Scientific applications, such as CESM, are also required to demonstrate a "computational readiness capability" to efficiently scale across and utilize 20% of the entire system. The 0,25 deg configuration of the spectral element dynamical core of the Community Atmosphere Model (CAM-SE), the atmospheric component of CESM, has been demonstrated to scale efficiently across more than 5,000 nodes (80,000 CPU cores) on Titan. The tracer transport routines of CAM-SE have also been ported to take advantage of the hybrid many-core architecture of Titan using GPUs [see EGU2014-4233], yielding over 2X speedup when transporting over 100 tracers. The high throughput I/O in CESM, based on the Parallel IO Library (PIO), is being further augmented to support even higher resolutions and enhance resiliency. The application performance of the individual runs are archived in a database and routinely analyzed to identify and rectify performance degradation during the course of the experiments. The various resources available at the OLCF now support a scientific workflow to facilitate high-resolution climate modelling. A high-speed center-wide parallel file system, called ATLAS, capable of 1 TB/s, is available on Titan as well as on the clusters used for analysis (Rhea) and visualization (Lens/EVEREST). Long-term archive is facilitated by the HPSS storage system. The Earth System Grid (ESG), featuring search & discovery, is also used to deliver data. The end-to-end workflow allows OLCF users to efficiently share data and publish results in a timely manner.

Preliminary Performance of CdZnTe Imaging Detector Prototypes

NASA Technical Reports Server (NTRS)

Ramsey, B.; Sharma, D. P.; Meisner, J.; Gostilo, V.; Ivanov, V.; Loupilov, A.; Sokolov, A.; Sipila, H.

1999-01-01

The promise of good energy and spatial resolution coupled with high efficiency and near-room-temperature operation has fuelled a large International effort to develop Cadmium-Zinc-Telluride (CdZnTe) for the hard-x-ray region. We present here preliminary results from our development of small-pixel imaging arrays fabricated on 5x5x1-mm and 5x5x2-mm spectroscopy and discriminator-grade material. Each array has 16 (4x4) 0.65-mm gold readout pads on a 0.75-mm pitch, with each pad connected to a discrete preamplifier via a pulse-welded gold wire. Each array is mounted on a 3-stage Peltier cooler and housed in an ion-pump-evacuated housing which also contains a hybrid micro-assembly for the 16 channels of electronics. We have investigated the energy resolution and approximate photopeak efficiency for each pixel at several energies and have used an ultra-fine beam x-ray generator to probe the performance at the pixel boundaries. Both arrays gave similar results, and at an optimum temperature of -20 C we achieved between 2 and 3% FWHM energy resolution at 60 keV and around 15% at 5.9 keV. We found that all the charge was contained within 1 pixel until very close to the pixels edge, where it would start to be shared with its neighbor. Even between pixels, all the charge would be appropriately shared with no apparently loss of efficiency or resolution. Full details of these measurements will be presented, together with their implications for future imaging-spectroscopy applications.

ESiWACE: A Center of Excellence for HPC applications to support cloud resolving earth system modelling

NASA Astrophysics Data System (ADS)

Biercamp, Joachim; Adamidis, Panagiotis; Neumann, Philipp

2017-04-01

With the exa-scale era approaching, length and time scales used for climate research on one hand and numerical weather prediction on the other hand blend into each other. The Centre of Excellence in Simulation of Weather and Climate in Europe (ESiWACE) represents a European consortium comprising partners from climate, weather and HPC in their effort to address key scientific challenges that both communities have in common. A particular challenge is to reach global models with spatial resolutions that allow simulating convective clouds and small-scale ocean eddies. These simulations would produce better predictions of trends and provide much more fidelity in the representation of high-impact regional events. However, running such models in operational mode, i.e with sufficient throughput in ensemble mode clearly will require exa-scale computing and data handling capability. We will discuss the ESiWACE initiative and relate it to work-in-progress on high-resolution simulations in Europe. We present recent strong scalability measurements from ESiWACE to demonstrate current computability in weather and climate simulation. A special focus in this particular talk is on the Icosahedal Nonhydrostatic (ICON) model used for a comparison of high resolution regional and global simulations with high quality observation data. We demonstrate that close-to-optimal parallel efficiency can be achieved in strong scaling global resolution experiments on Mistral/DKRZ, e.g. 94% for 5km resolution simulations using 36k cores on Mistral/DKRZ. Based on our scalability and high-resolution experiments, we deduce and extrapolate future capabilities for ICON that are expected for weather and climate research at exascale.

6 x 6-cm fully depleted pn-junction CCD for high-resolution spectroscopy in the 0.1- to 15-keV photon energy range

NASA Astrophysics Data System (ADS)

von Zanthier, Christoph; Holl, Peter; Kemmer, Josef; Lechner, Peter; Maier, B.; Soltau, Heike; Stoetter, R.; Braeuninger, Heinrich W.; Dennerl, Konrad; Haberl, Frank; Hartmann, R.; Hartner, Gisela D.; Hippmann, H.; Kastelic, E.; Kink, W.; Krause, N.; Meidinger, Norbert; Metzner, G.; Pfeffermann, Elmar; Popp, M.; Reppin, Claus; Stoetter, Diana; Strueder, Lothar; Truemper, Joachim; Weber, U.; Carathanassis, D.; Engelhard, S.; Gebhart, Th.; Hauff, D.; Lutz, G.; Richter, R. H.; Seitz, H.; Solc, P.; Bihler, Edgar; Boettcher, H.; Kendziorra, Eckhard; Kraemer, J.; Pflueger, Bernhard; Staubert, Ruediger

1998-04-01

The concept and performance of the fully depleted pn- junction CCD system, developed for the European XMM- and the German ABRIXAS-satellite missions for soft x-ray imaging and spectroscopy in the 0.1 keV to 15 keV photon range, is presented. The 58 mm X 60 mm large pn-CCD array uses pn- junctions for registers and for the backside instead of MOS registers. This concept naturally allows to fully deplete the detector volume to make it an efficient detector to photons with energies up to 15 keV. For high detection efficiency in the soft x-ray region down to 100 eV, an ultrathin pn-CCD backside deadlayer has been realized. Each pn-CCD-channel is equipped with an on-chip JFET amplifier which, in combination with the CAMEX-amplifier and multiplexing chip, facilitates parallel readout with a pixel read rate of 3 MHz and an electronic noise floor of ENC < e-. With the complete parallel readout, very fast pn-CCD readout modi can be implemented in the system which allow for high resolution photon spectroscopy of even the brightest x-ray sources in the sky.

Charge Collection in Hybrid Perovskite Solar Cells: Relation to the Nanoscale Elemental Distribution

DOE PAGES

Stuckelberger, Michael; Nietzold, Tara; Hall, Genevieve N.; ...

2016-12-19

Unveiling the correlation between elemental composition, Fermi-level splitting, and charge collection in perovskite solar cells (PSCs) when exposed to different environments is crucial to understanding the origin of defects. This will enable defect engineering to achieve high-performance and long-lasting PSCs. Here, in this paper, we measured, for the first time, the spatial distribution and charge-collection efficiency at the nanoscale by synchrotron-based X-ray fluorescence (XRF) and X-ray beam-induced current (XBIC) with subgrain resolution, and we observe a correlation between Pb/I ratio and charge-collection efficiency. In contrast with other thin-film solar cells, PSCs are highly sensitive to ambient conditions (atmosphere and illumination).more » As the XRF and XBIC measurements were conducted in vacuum under an X-ray source illumination, the impact of measurement conditions on the cells needs to be taken into account. Furthermore, necessary conditions for quantification of XRF/XBIC measurements, such as film homogeneity, are not fulfilled in the case of PSCs. Finally, we will discuss fundamentals of XRF/XBIC measurements of PSCs that will enable reliable, quantitative, high-resolution measurements of elemental distribution and charge collection.« less

FIB/SEM technology and high-throughput 3D reconstruction of dendritic spines and synapses in GFP-labeled adult-generated neurons.

PubMed

Bosch, Carles; Martínez, Albert; Masachs, Nuria; Teixeira, Cátia M; Fernaud, Isabel; Ulloa, Fausto; Pérez-Martínez, Esther; Lois, Carlos; Comella, Joan X; DeFelipe, Javier; Merchán-Pérez, Angel; Soriano, Eduardo

2015-01-01

The fine analysis of synaptic contacts is usually performed using transmission electron microscopy (TEM) and its combination with neuronal labeling techniques. However, the complex 3D architecture of neuronal samples calls for their reconstruction from serial sections. Here we show that focused ion beam/scanning electron microscopy (FIB/SEM) allows efficient, complete, and automatic 3D reconstruction of identified dendrites, including their spines and synapses, from GFP/DAB-labeled neurons, with a resolution comparable to that of TEM. We applied this technology to analyze the synaptogenesis of labeled adult-generated granule cells (GCs) in mice. 3D reconstruction of dendritic spines in GCs aged 3-4 and 8-9 weeks revealed two different stages of dendritic spine development and unexpected features of synapse formation, including vacant and branched dendritic spines and presynaptic terminals establishing synapses with up to 10 dendritic spines. Given the reliability, efficiency, and high resolution of FIB/SEM technology and the wide use of DAB in conventional EM, we consider FIB/SEM fundamental for the detailed characterization of identified synaptic contacts in neurons in a high-throughput manner.

FIB/SEM technology and high-throughput 3D reconstruction of dendritic spines and synapses in GFP-labeled adult-generated neurons

PubMed Central

Bosch, Carles; Martínez, Albert; Masachs, Nuria; Teixeira, Cátia M.; Fernaud, Isabel; Ulloa, Fausto; Pérez-Martínez, Esther; Lois, Carlos; Comella, Joan X.; DeFelipe, Javier; Merchán-Pérez, Angel; Soriano, Eduardo

2015-01-01

The fine analysis of synaptic contacts is usually performed using transmission electron microscopy (TEM) and its combination with neuronal labeling techniques. However, the complex 3D architecture of neuronal samples calls for their reconstruction from serial sections. Here we show that focused ion beam/scanning electron microscopy (FIB/SEM) allows efficient, complete, and automatic 3D reconstruction of identified dendrites, including their spines and synapses, from GFP/DAB-labeled neurons, with a resolution comparable to that of TEM. We applied this technology to analyze the synaptogenesis of labeled adult-generated granule cells (GCs) in mice. 3D reconstruction of dendritic spines in GCs aged 3–4 and 8–9 weeks revealed two different stages of dendritic spine development and unexpected features of synapse formation, including vacant and branched dendritic spines and presynaptic terminals establishing synapses with up to 10 dendritic spines. Given the reliability, efficiency, and high resolution of FIB/SEM technology and the wide use of DAB in conventional EM, we consider FIB/SEM fundamental for the detailed characterization of identified synaptic contacts in neurons in a high-throughput manner. PMID:26052271

Precision timing detectors with cadmium-telluride sensor

NASA Astrophysics Data System (ADS)

Bornheim, A.; Pena, C.; Spiropulu, M.; Xie, S.; Zhang, Z.

2017-09-01

Precision timing detectors for high energy physics experiments with temporal resolutions of a few 10 ps are of pivotal importance to master the challenges posed by the highest energy particle accelerators such as the LHC. Calorimetric timing measurements have been a focus of recent research, enabled by exploiting the temporal coherence of electromagnetic showers. Scintillating crystals with high light yield as well as silicon sensors are viable sensitive materials for sampling calorimeters. Silicon sensors have very high efficiency for charged particles. However, their sensitivity to photons, which comprise a large fraction of the electromagnetic shower, is limited. To enhance the efficiency of detecting photons, materials with higher atomic numbers than silicon are preferable. In this paper we present test beam measurements with a Cadmium-Telluride (CdTe) sensor as the active element of a secondary emission calorimeter with focus on the timing performance of the detector. A Schottky type CdTe sensor with an active area of 1cm2 and a thickness of 1 mm is used in an arrangement with tungsten and lead absorbers. Measurements are performed with electron beams in the energy range from 2 GeV to 200 GeV. A timing resolution of 20 ps is achieved under the best conditions.

A Class of High-Resolution Explicit and Implicit Shock-Capturing Methods

NASA Technical Reports Server (NTRS)

Yee, H. C.

1994-01-01

The development of shock-capturing finite difference methods for hyperbolic conservation laws has been a rapidly growing area for the last decade. Many of the fundamental concepts, state-of-the-art developments and applications to fluid dynamics problems can only be found in meeting proceedings, scientific journals and internal reports. This paper attempts to give a unified and generalized formulation of a class of high-resolution, explicit and implicit shock capturing methods, and to illustrate their versatility in various steady and unsteady complex shock waves, perfect gases, equilibrium real gases and nonequilibrium flow computations. These numerical methods are formulated for the purpose of ease and efficient implementation into a practical computer code. The various constructions of high-resolution shock-capturing methods fall nicely into the present framework and a computer code can be implemented with the various methods as separate modules. Included is a systematic overview of the basic design principle of the various related numerical methods. Special emphasis will be on the construction of the basic nonlinear, spatially second and third-order schemes for nonlinear scalar hyperbolic conservation laws and the methods of extending these nonlinear scalar schemes to nonlinear systems via the approximate Riemann solvers and flux-vector splitting approaches. Generalization of these methods to efficiently include real gases and large systems of nonequilibrium flows will be discussed. Some perbolic conservation laws to problems containing stiff source terms and terms and shock waves are also included. The performance of some of these schemes is illustrated by numerical examples for one-, two- and three-dimensional gas-dynamics problems. The use of the Lax-Friedrichs numerical flux to obtain high-resolution shock-capturing schemes is generalized. This method can be extended to nonlinear systems of equations without the use of Riemann solvers or flux-vector splitting approaches and thus provides a large savings for multidimensional, equilibrium real gases and nonequilibrium flow computations.

Performance of a Micro-Strip Gas Chamber for event wise, high rate thermal neutron detection with accurate 2D position determination

NASA Astrophysics Data System (ADS)

Mindur, B.; Alimov, S.; Fiutowski, T.; Schulz, C.; Wilpert, T.

2014-12-01

A two-dimensional (2D) position sensitive detector for neutron scattering applications based on low-pressure gas amplification and micro-strip technology was built and tested with an innovative readout electronics and data acquisition system. This detector contains a thin solid neutron converter and was developed for time- and thus wavelength-resolved neutron detection in single-event counting mode, which improves the image contrast in comparison with integrating detectors. The prototype detector of a Micro-Strip Gas Chamber (MSGC) was built with a solid natGd/CsI thermal neutron converter for spatial resolutions of about 100 μm and counting rates up to 107 neutrons/s. For attaining very high spatial resolutions and counting rates via micro-strip readout with centre-of-gravity evaluation of the signal amplitude distributions, a fast, channel-wise, self-triggering ASIC was developed. The front-end chips (MSGCROCs), which are very first signal processing components, are read out into powerful ADC-FPGA boards for on-line data processing and thereafter via Gigabit Ethernet link into the data receiving PC. The workstation PC is controlled by a modular, high performance dedicated software suite. Such a fast and accurate system is crucial for efficient radiography/tomography, diffraction or imaging applications based on high flux thermal neutron beam. In this paper a brief description of the detector concept with its operation principles, readout electronics requirements and design together with the signals processing stages performed in hardware and software are presented. In more detail the neutron test beam conditions and measurement results are reported. The focus of this paper is on the system integration, two dimensional spatial resolution, the time resolution of the readout system and the imaging capabilities of the overall setup. The detection efficiency of the detector prototype is estimated as well.

Regional Climate Simulation with a Variable Resolution Stretched Grid GCM: The Regional Down-Scaling Effects

NASA Technical Reports Server (NTRS)

Fox-Rabinovitz, Michael S.; Takacs, Lawrence L.; Suarez, Max; Sawyer, William; Govindaraju, Ravi C.

1999-01-01

The results obtained with the variable resolution stretched grid (SG) GEOS GCM (Goddard Earth Observing System General Circulation Models) are discussed, with the emphasis on the regional down-scaling effects and their dependence on the stretched grid design and parameters. A variable resolution SG-GCM and SG-DAS using a global stretched grid with fine resolution over an area of interest, is a viable new approach to REGIONAL and subregional CLIMATE studies and applications. The stretched grid approach is an ideal tool for representing regional to global scale interactions. It is an alternative to the widely used nested grid approach introduced a decade ago as a pioneering step in regional climate modeling. The GEOS SG-GCM is used for simulations of the anomalous U.S. climate events of 1988 drought and 1993 flood, with enhanced regional resolution. The height low level jet, precipitation and other diagnostic patterns are successfully simulated and show the efficient down-scaling over the area of interest the U.S. An imitation of the nested grid approach is performed using the developed SG-DAS (Data Assimilation System) that incorporates the SG-GCM. The SG-DAS is run with withholding data over the area of interest. The design immitates the nested grid framework with boundary conditions provided from analyses. No boundary condition buffer is needed for the case due to the global domain of integration used for the SG-GCM and SG-DAS. The experiments based on the newly developed versions of the GEOS SG-GCM and SG-DAS, with finer 0.5 degree (and higher) regional resolution, are briefly discussed. The major aspects of parallelization of the SG-GCM code are outlined. The KEY OBJECTIVES of the study are: 1) obtaining an efficient DOWN-SCALING over the area of interest with fine and very fine resolution; 2) providing CONSISTENT interactions between regional and global scales including the consistent representation of regional ENERGY and WATER BALANCES; 3) providing a high computational efficiency for future SG-GCM and SG-DAS versions using PARALLEL codes.

Ultra-high-speed variable focus optics for novel applications in advanced imaging

NASA Astrophysics Data System (ADS)

Kang, S.; Dotsenko, E.; Amrhein, D.; Theriault, C.; Arnold, C. B.

2018-02-01

With the advancement of ultra-fast manufacturing technologies, high speed imaging with high 3D resolution has become increasingly important. Here we show the use of an ultra-high-speed variable focus optical element, the TAG Lens, to enable new ways to acquire 3D information from an object. The TAG Lens uses sound to adjust the index of refraction profile in a liquid and thereby can achieve focal scanning rates greater than 100 kHz. When combined with a high-speed pulsed LED and a high-speed camera, we can exploit this phenomenon to achieve high-resolution imaging through large depths. By combining the image acquisition with digital image processing, we can extract relevant parameters such as tilt and angle information from objects in the image. Due to the high speeds at which images can be collected and processed, we believe this technique can be used as an efficient method of industrial inspection and metrology for high throughput applications.

Evaluating the impact of lower resolutions of digital elevation model on rainfall-runoff modeling for ungauged catchments.

PubMed

Ghumman, Abul Razzaq; Al-Salamah, Ibrahim Saleh; AlSaleem, Saleem Saleh; Haider, Husnain

2017-02-01

Geomorphological instantaneous unit hydrograph (GIUH) usually uses geomorphologic parameters of catchment estimated from digital elevation model (DEM) for rainfall-runoff modeling of ungauged watersheds with limited data. Higher resolutions (e.g., 5 or 10 m) of DEM play an important role in the accuracy of rainfall-runoff models; however, such resolutions are expansive to obtain and require much greater efforts and time for preparation of inputs. In this research, a modeling framework is developed to evaluate the impact of lower resolutions (i.e., 30 and 90 m) of DEM on the accuracy of Clark GIUH model. Observed rainfall-runoff data of a 202-km 2 catchment in a semiarid region was used to develop direct runoff hydrographs for nine rainfall events. Geographical information system was used to process both the DEMs. Model accuracy and errors were estimated by comparing the model results with the observed data. The study found (i) high model efficiencies greater than 90% for both the resolutions, and (ii) that the efficiency of Clark GIUH model does not significantly increase by enhancing the resolution of the DEM from 90 to 30 m. Thus, it is feasible to use lower resolutions (i.e., 90 m) of DEM in the estimation of peak runoff in ungauged catchments with relatively less efforts. Through sensitivity analysis (Monte Carlo simulations), the kinematic wave parameter and stream length ratio are found to be the most significant parameters in velocity and peak flow estimations, respectively; thus, they need to be carefully estimated for calculation of direct runoff in ungauged watersheds using Clark GIUH model.

Increasing horizontal resolution in numerical weather prediction and climate simulations: illusion or panacea?

PubMed

Wedi, Nils P

2014-06-28

The steady path of doubling the global horizontal resolution approximately every 8 years in numerical weather prediction (NWP) at the European Centre for Medium Range Weather Forecasts may be substantially altered with emerging novel computing architectures. It coincides with the need to appropriately address and determine forecast uncertainty with increasing resolution, in particular, when convective-scale motions start to be resolved. Blunt increases in the model resolution will quickly become unaffordable and may not lead to improved NWP forecasts. Consequently, there is a need to accordingly adjust proven numerical techniques. An informed decision on the modelling strategy for harnessing exascale, massively parallel computing power thus also requires a deeper understanding of the sensitivity to uncertainty--for each part of the model--and ultimately a deeper understanding of multi-scale interactions in the atmosphere and their numerical realization in ultra-high-resolution NWP and climate simulations. This paper explores opportunities for substantial increases in the forecast efficiency by judicious adjustment of the formal accuracy or relative resolution in the spectral and physical space. One path is to reduce the formal accuracy by which the spectral transforms are computed. The other pathway explores the importance of the ratio used for the horizontal resolution in gridpoint space versus wavenumbers in spectral space. This is relevant for both high-resolution simulations as well as ensemble-based uncertainty estimation. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

High-resolution modelling of waves, currents and sediment transport in the Catalan Sea.

NASA Astrophysics Data System (ADS)

Sánchez-Arcilla, Agustín; Grifoll, Manel; Pallares, Elena; Espino, Manuel

2013-04-01

In order to investigate coastal shelf dynamics, a sequence of high resolution multi-scale models have been implemented for the Catalan shelf (North-western Mediterranean Sea). The suite consists of a set of increasing-resolution nested models, based on the circulation model ROMS (Regional Ocean Modelling System), the wave model SWAN (Simulation Waves Nearshore) and the sediment transport model CSTM (Community Sediment Transport Model), covering different ranges of spatial (from ~1 km at shelf-slope regions to ~40 m around river mouth or local beaches) and temporal scales (from storms events to seasonal variability). Contributions in the understanding of local processes such as along-shelf dynamics in the inner-shelf, sediment dispersal from the river discharge or bi-directional wave-current interactions under different synoptic conditions and resolution have been obtained using the Catalan Coast as a pilot site. Numerical results have been compared with "ad-hoc" intensive field campaigns, data from observational models and remote sensing products. The results exhibit acceptable agreement with observations and the investigation has allowed developing generic knowledge and more efficient (process-based) strategies for the coastal and shelf management.

Efficient conditioned pain modulation despite pain persistence in painful diabetic neuropathy.

PubMed

Granovsky, Yelena; Nahman-Averbuch, Hadas; Khamaisi, Mogher; Granot, Michal

2017-05-01

Alleviation of pain, by either medical or surgical therapy, is accompanied by transition from less efficient, or pro-nociceptive, to efficient conditioned pain modulation (CPM). Spontaneous decrease or resolution of pain with disease progression is reported for some patients with painful diabetic neuropathy (PDN). To explore whether CPM changes similarly in parallel to spontaneous resolution of pain in PDN patients. In this cross-sectional study, thirty-three patients with PDN underwent psychophysical assessment of pain modulation on the forearm, remote from the clinical pain. Pain duration was not correlated with neuropathic pain intensity, yet, it correlated with CPM efficiency; patients with longer pain duration had same pain level, but more efficient CPM than those with short-pain duration (ρ = -0.417; P = 0.025, Spearman correlation). Patients with pain more than 2 years (median split) expressed efficient CPM that was not different from that of healthy controls. These patients also had lower temporal summation of pain than the short-pain duration patients group ( P < 0.05). The 2 patient groups did not differ in clinical pain characteristics or use of analgesics. Pro-nociception, expressed by less efficient CPM and high temporal summation that usually accompanies clinical painful conditions, seems to "normalize" with chronicity of the pain syndrome. This is despite continuing pain, suggesting that pro-nociceptivity in pain syndromes is multifactorial. Because the pain modulation profile affects success of therapy, this suggests that different drugs might express different efficacy pending on duration of the pain in patients with PDN.

Color image guided depth image super resolution using fusion filter

NASA Astrophysics Data System (ADS)

He, Jin; Liang, Bin; He, Ying; Yang, Jun

2018-04-01

Depth cameras are currently playing an important role in many areas. However, most of them can only obtain lowresolution (LR) depth images. Color cameras can easily provide high-resolution (HR) color images. Using color image as a guide image is an efficient way to get a HR depth image. In this paper, we propose a depth image super resolution (SR) algorithm, which uses a HR color image as a guide image and a LR depth image as input. We use the fusion filter of guided filter and edge based joint bilateral filter to get HR depth image. Our experimental results on Middlebury 2005 datasets show that our method can provide better quality in HR depth images both numerically and visually.

Picometer-resolution dual-comb spectroscopy with a free-running fiber laser.

PubMed

Zhao, Xin; Hu, Guoqing; Zhao, Bofeng; Li, Cui; Pan, Yingling; Liu, Ya; Yasui, Takeshi; Zheng, Zheng

2016-09-19

Dual-comb spectroscopy holds the promise as real-time, high-resolution spectroscopy tools. However, in its conventional schemes, the stringent requirement on the coherence between two lasers requires sophisticated control systems. By replacing control electronics with an all-optical dual-comb lasing scheme, a simplified dual-comb spectroscopy scheme is demonstrated using one dual-wavelength, passively mode-locked fiber laser. Pulses with a intracavity-dispersion-determined repetition-frequency difference are shown to have good mutual coherence and stability. Capability to resolve the comb teeth and a picometer-wide optical spectral resolution are demonstrated using a simple data acquisition system. Energy-efficient, free-running fiber lasers with a small comb-tooth-spacing could enable low-cost dual-comb systems.

Optimizing Imaging Instruments for Emission Mammography

NASA Astrophysics Data System (ADS)

Weinberg, Irving N.

1996-05-01

Clinical studies have demonstrated that radiotracer methods can noninvasively detect breast cancers in vivo(L.P. Adler, J.P.Crowe, N.K. Al-Kaisis, et al, Radiology 187,743-750 (1993)) (I. Khalkhali, I. Mena, E. Jouanne, et al, J. Am. Coll. Surg. 178, 491-497 (1994)). Due to spatial resolution and count efficiency considerations, users of conventional nuclear medicine instruments have had difficulty in detecting subcentimeter cancers. This limitation is unfortunate, since cancer therapy is generally most efficacious when tumor diameter at detection is less than a centimeter. A more subtle limitation of conventional nuclear medicine imaging instruments is that they are poorly suited to guiding interventions. With the assistance of C.J. Thompson from McGill University, and the CEBAF Detector Physics Group, we have explored the possibility of configuring detectors for nuclear medicine imaging devices into geometries that resemble conventional x-ray mammography cameras(I.N. Weinberg, U.S.Patent 5,252,830 (1993)). Phantom and pilot clinical studies suggest that applying breast compression within such geometries may offer several advantages(C.J. Thompson, K. Murthy, I.N. Weinberg, et al, Med. Physics 21, 259-538 (1994)): For coincident detection of positron emitters, efficiency and spatial resolution are improved by bringing the detectors very close to the source (the breast tumor). For single-photon detection, attenuation due to overlying tissue is reduced. Since, for a high-efficiency collimator, spatial resolution worsens with increasing source to collimator distance, adoption of compression allows more efficient collimators to be employed. Economics are favorable in that detectors can be deployed in the region of interest, rather than around the entire body, and that such detectors can be mounted in conventional mammographic gantries. The application of conventional mammographic geometry promises to assist physicians in conducting radiotracer-guided biopsies, and in correlating biochemical with x-ray data. The primary challenge of conducting studies with dedicated emission mammography devices has been dealing with high count rates due to cardiac activity.

In-process fault detection for textile fabric production: onloom imaging

NASA Astrophysics Data System (ADS)

Neumann, Florian; Holtermann, Timm; Schneider, Dorian; Kulczycki, Ashley; Gries, Thomas; Aach, Til

2011-05-01

Constant and traceable high fabric quality is of high importance both for technical and for high-quality conventional fabrics. Usually, quality inspection is carried out by trained personal, whose detection rate and maximum period of concentration are limited. Low resolution automated fabric inspection machines using texture analysis were developed. Since 2003, systems for the in-process inspection on weaving machines ("onloom") are commercially available. With these defects can be detected, but not measured quantitative precisely. Most systems are also prone to inevitable machine vibrations. Feedback loops for fault prevention are not established. Technology has evolved since 2003: Camera and computer prices dropped, resolutions were enhanced, recording speeds increased. These are the preconditions for real-time processing of high-resolution images. So far, these new technological achievements are not used in textile fabric production. For efficient use, a measurement system must be integrated into the weaving process; new algorithms for defect detection and measurement must be developed. The goal of the joint project is the development of a modern machine vision system for nondestructive onloom fabric inspection. The system consists of a vibration-resistant machine integration, a high-resolution machine vision system, and new, reliable, and robust algorithms with quality database for defect documentation. The system is meant to detect, measure, and classify at least 80 % of economically relevant defects. Concepts for feedback loops into the weaving process will be pointed out.

Integration of High-resolution Data for Temporal Bone Surgical Simulations

PubMed Central

Wiet, Gregory J.; Stredney, Don; Powell, Kimerly; Hittle, Brad; Kerwin, Thomas

2016-01-01

Purpose To report on the state of the art in obtaining high-resolution 3D data of the microanatomy of the temporal bone and to process that data for integration into a surgical simulator. Specifically, we report on our experience in this area and discuss the issues involved to further the field. Data Sources Current temporal bone image acquisition and image processing established in the literature as well as in house methodological development. Review Methods We reviewed the current English literature for the techniques used in computer-based temporal bone simulation systems to obtain and process anatomical data for use within the simulation. Search terms included “temporal bone simulation, surgical simulation, temporal bone.” Articles were chosen and reviewed that directly addressed data acquisition and processing/segmentation and enhancement with emphasis given to computer based systems. We present the results from this review in relationship to our approach. Conclusions High-resolution CT imaging (≤100μm voxel resolution), along with unique image processing and rendering algorithms, and structure specific enhancement are needed for high-level training and assessment using temporal bone surgical simulators. Higher resolution clinical scanning and automated processes that run in efficient time frames are needed before these systems can routinely support pre-surgical planning. Additionally, protocols such as that provided in this manuscript need to be disseminated to increase the number and variety of virtual temporal bones available for training and performance assessment. PMID:26762105

A new implementation of full resolution SBAS-DInSAR processing chain for the effective monitoring of structures and infrastructures

NASA Astrophysics Data System (ADS)

Bonano, Manuela; Buonanno, Sabatino; Ojha, Chandrakanta; Berardino, Paolo; Lanari, Riccardo; Zeni, Giovanni; Manunta, Michele

2017-04-01

The advanced DInSAR technique referred to as Small BAseline Subset (SBAS) algorithm has already largely demonstrated its effectiveness to carry out multi-scale and multi-platform surface deformation analyses relevant to both natural and man-made hazards. Thanks to its capability to generate displacement maps and long-term deformation time series at both regional (low resolution analysis) and local (full resolution analysis) spatial scales, it allows to get more insights on the spatial and temporal patterns of localized displacements relevant to single buildings and infrastructures over extended urban areas, with a key role in supporting risk mitigation and preservation activities. The extensive application of the multi-scale SBAS-DInSAR approach in many scientific contexts has gone hand in hand with new SAR satellite mission development, characterized by different frequency bands, spatial resolution, revisit times and ground coverage. This brought to the generation of huge DInSAR data stacks to be efficiently handled, processed and archived, with a strong impact on both the data storage and the computational requirements needed for generating the full resolution SBAS-DInSAR results. Accordingly, innovative and effective solutions for the automatic processing of massive SAR data archives and for the operational management of the derived SBAS-DInSAR products need to be designed and implemented, by exploiting the high efficiency (in terms of portability, scalability and computing performances) of the new ICT methodologies. In this work, we present a novel parallel implementation of the full resolution SBAS-DInSAR processing chain, aimed at investigating localized displacements affecting single buildings and infrastructures relevant to very large urban areas, relying on different granularity level parallelization strategies. The image granularity level is applied in most steps of the SBAS-DInSAR processing chain and exploits the multiprocessor systems with distributed memory. Moreover, in some processing steps very heavy from the computational point of view, the Graphical Processing Units (GPU) are exploited for the processing of blocks working on a pixel-by-pixel basis, requiring strong modifications on some key parts of the sequential full resolution SBAS-DInSAR processing chain. GPU processing is implemented by efficiently exploiting parallel processing architectures (as CUDA) for increasing the computing performances, in terms of optimization of the available GPU memory, as well as reduction of the Input/Output operations on the GPU and of the whole processing time for specific blocks w.r.t. the corresponding sequential implementation, particularly critical in presence of huge DInSAR datasets. Moreover, to efficiently handle the massive amount of DInSAR measurements provided by the new generation SAR constellations (CSK and Sentinel-1), we perform a proper re-design strategy aimed at the robust assimilation of the full resolution SBAS-DInSAR results into the web-based Geonode platform of the Spatial Data Infrastructure, thus allowing the efficient management, analysis and integration of the interferometric results with different data sources.

Continuous probing of cold complex molecules with infrared frequency comb spectroscopy

NASA Astrophysics Data System (ADS)

Spaun, Ben; Changala, P. Bryan; Patterson, David; Bjork, Bryce J.; Heckl, Oliver H.; Doyle, John M.; Ye, Jun

2016-05-01

For more than half a century, high-resolution infrared spectroscopy has played a crucial role in probing molecular structure and dynamics. Such studies have so far been largely restricted to relatively small and simple systems, because at room temperature even molecules of modest size already occupy many millions of rotational/vibrational states, yielding highly congested spectra that are difficult to assign. Targeting more complex molecules requires methods that can record broadband infrared spectra (that is, spanning multiple vibrational bands) with both high resolution and high sensitivity. However, infrared spectroscopic techniques have hitherto been limited either by narrow bandwidth and long acquisition time, or by low sensitivity and resolution. Cavity-enhanced direct frequency comb spectroscopy (CE-DFCS) combines the inherent broad bandwidth and high resolution of an optical frequency comb with the high detection sensitivity provided by a high-finesse enhancement cavity, but it still suffers from spectral congestion. Here we show that this problem can be overcome by using buffer gas cooling to produce continuous, cold samples of molecules that are then subjected to CE-DFCS. This integration allows us to acquire a rotationally resolved direct absorption spectrum in the C-H stretching region of nitromethane, a model system that challenges our understanding of large-amplitude vibrational motion. We have also used this technique on several large organic molecules that are of fundamental spectroscopic and astrochemical relevance, including naphthalene, adamantane and hexamethylenetetramine. These findings establish the value of our approach for studying much larger and more complex molecules than have been probed so far, enabling complex molecules and their kinetics to be studied with orders-of-magnitude improvements in efficiency, spectral resolution and specificity.

smoothG

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

Barker, Andrew T.; Gelever, Stephan A.; Lee, Chak S.

2017-12-12

smoothG is a collection of parallel C++ classes/functions that algebraically constructs reduced models of different resolutions from a given high-fidelity graph model. In addition, smoothG also provides efficient linear solvers for the reduced models. Other than pure graph problem, the software finds its application in subsurface flow and power grid simulations in which graph Laplacians are found

Coupled multi-group neutron photon transport for the simulation of high-resolution gamma-ray spectroscopy applications

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

Burns, Kimberly A.

2009-08-01

The accurate and efficient simulation of coupled neutron-photon problems is necessary for several important radiation detection applications. Examples include the detection of nuclear threats concealed in cargo containers and prompt gamma neutron activation analysis for nondestructive determination of elemental composition of unknown samples.

An intercomparison study of TSM, SEBS, and SEBAL using high-resolution imagery and lysimetric data

USDA-ARS?s Scientific Manuscript database

Over the past three decades, numerous remote sensing based ET mapping algorithms were developed. These algorithms provided a robust, economical, and efficient tool for ET estimations at field and regional scales. The Two Source Model (TSM), Surface Energy Balance System (SEBS), and Surface Energy Ba...

Socio-Pedagogical Portrait of a Master's Degree Student in International Arbitration: Experience of Great Britain

ERIC Educational Resources Information Center

Nagorna, Olga

2016-01-01

International arbitration as the efficient means of alternative dispute resolution has become, due to globalization, a highly specialised service rendered by professionals. Master's degree program (LLM) completion enables those interested to become competent and competitive specialists in arbitration on the international arena. Great Britain has…

Exposomics research using suspect screening and non-targeted analysis methods and tools at the U.S. Environmental Protection Agency (ASMS Presentation)

EPA Science Inventory

High-resolution mass spectrometry (HRMS) is used for suspect screening (SSA) and non-targeted analysis (NTA) in an attempt to characterize xenobiotic chemicals in various samples broadly and efficiently. These important techniques aid characterization of the exposome, the totalit...

Refining FIA plot locations using LiDAR point clouds

Treesearch

Charlie Schrader-Patton; Greg C. Liknes; Demetrios Gatziolis; Brian M. Wing; Mark D. Nelson; Patrick D. Miles; Josh Bixby; Daniel G. Wendt; Dennis Kepler; Abbey Schaaf

2015-01-01

Forest Inventory and Analysis (FIA) plot location coordinate precision is often insufficient for use with high resolution remotely sensed data, thereby limiting the use of these plots for geospatial applications and reducing the validity of models that assume the locations are precise. A practical and efficient method is needed to improve coordinate precision. To...

High-resolution Thermal Micro-imaging Using Europium Chelate Luminescent Coatings

DOE PAGES

Benseman, Timothy M.; Hao, Yang; Vlasko-Vlasov, Vitalii K.; ...

2017-04-16

Europium thenoyltrifluoroacentonate (EuTFC) has an optical luminescence line at 612 nm, whose activation efficiency decreases strongly with temperature. If a sample coated with a thin film of this material is micro-imaged, the 612 nm luminescent response intensity may be converted into a direct map of sample surface temperature.

An efficient interpolation filter VLSI architecture for HEVC standard

NASA Astrophysics Data System (ADS)

Zhou, Wei; Zhou, Xin; Lian, Xiaocong; Liu, Zhenyu; Liu, Xiaoxiang

2015-12-01

The next-generation video coding standard of High-Efficiency Video Coding (HEVC) is especially efficient for coding high-resolution video such as 8K-ultra-high-definition (UHD) video. Fractional motion estimation in HEVC presents a significant challenge in clock latency and area cost as it consumes more than 40 % of the total encoding time and thus results in high computational complexity. With aims at supporting 8K-UHD video applications, an efficient interpolation filter VLSI architecture for HEVC is proposed in this paper. Firstly, a new interpolation filter algorithm based on the 8-pixel interpolation unit is proposed in this paper. It can save 19.7 % processing time on average with acceptable coding quality degradation. Based on the proposed algorithm, an efficient interpolation filter VLSI architecture, composed of a reused data path of interpolation, an efficient memory organization, and a reconfigurable pipeline interpolation filter engine, is presented to reduce the implement hardware area and achieve high throughput. The final VLSI implementation only requires 37.2k gates in a standard 90-nm CMOS technology at an operating frequency of 240 MHz. The proposed architecture can be reused for either half-pixel interpolation or quarter-pixel interpolation, which can reduce the area cost for about 131,040 bits RAM. The processing latency of our proposed VLSI architecture can support the real-time processing of 4:2:0 format 7680 × 4320@78fps video sequences.

QUAL-NET, a high temporal-resolution eutrophication model for large hydrographic networks

NASA Astrophysics Data System (ADS)

Minaudo, Camille; Curie, Florence; Jullian, Yann; Gassama, Nathalie; Moatar, Florentina

2018-04-01

To allow climate change impact assessment of water quality in river systems, the scientific community lacks efficient deterministic models able to simulate hydrological and biogeochemical processes in drainage networks at the regional scale, with high temporal resolution and water temperature explicitly determined. The model QUALity-NETwork (QUAL-NET) was developed and tested on the Middle Loire River Corridor, a sub-catchment of the Loire River in France, prone to eutrophication. Hourly variations computed efficiently by the model helped disentangle the complex interactions existing between hydrological and biological processes across different timescales. Phosphorus (P) availability was the most constraining factor for phytoplankton development in the Loire River, but simulating bacterial dynamics in QUAL-NET surprisingly evidenced large amounts of organic matter recycled within the water column through the microbial loop, which delivered significant fluxes of available P and enhanced phytoplankton growth. This explained why severe blooms still occur in the Loire River despite large P input reductions since 1990. QUAL-NET could be used to study past evolutions or predict future trajectories under climate change and land use scenarios.

High-accurate optical vector analysis based on optical single-sideband modulation

NASA Astrophysics Data System (ADS)

Xue, Min; Pan, Shilong

2016-11-01

Most of the efforts devoted to the area of optical communications were on the improvement of the optical spectral efficiency. Varies innovative optical devices are thus developed to finely manipulate the optical spectrum. Knowing the spectral responses of these devices, including the magnitude, phase and polarization responses, is of great importance for their fabrication and application. To achieve high-resolution characterization, optical vector analyzers (OVAs) based on optical single-sideband (OSSB) modulation have been proposed and developed. Benefiting from the mature and highresolution microwave technologies, the OSSB-based OVA can potentially achieve a resolution of sub-Hz. However, the accuracy is restricted by the measurement errors induced by the unwanted first-order sideband and the high-order sidebands in the OSSB signal, since electrical-to-optical conversion and optical-to-electrical conversion are essentially required to achieve high-resolution frequency sweeping and extract the magnitude and phase information in the electrical domain. Recently, great efforts have been devoted to improve the accuracy of the OSSB-based OVA. In this paper, the influence of the unwanted-sideband induced measurement errors and techniques for implementing high-accurate OSSB-based OVAs are discussed.

New opportunities in quasi elastic neutron scattering spectroscopy

NASA Astrophysics Data System (ADS)

Mezei, F.; Russina, M.

2001-07-01

The high energy resolution usually required in quasi elastic neutron scattering (QENS) spectroscopy is commonly achieved by the use of cold neutrons. This is one of the important research areas where the majority of current work is done on instruments on continuous reactor sources. One particular reason for this is the capability of continuous source time-of-flight spectrometers to use instrumental parameters optimally adapted for best data collection efficiency in each experiment. These parameters include the pulse repetition rate and the length of the pulses to achieve optimal balance between resolution and intensity. In addition, the disc chopper systems used provide perfect symmetrical line shapes with no tails and low background. Recent development of a set of novel techniques enhance the efficiency of cold neutron spectroscopy on existing and future spallation sources in a dramatic fashion. These techniques involve the use of extended pulse length, high intensity coupled moderators, disc chopper systems and advanced neutron optical beam delivery, and they will enable Lujan center at Los Alamos to surpass the best existing reactor instruments in time-of-flight QENS work by more than on order of magnitude in terms of beam flux on the sample. Other applications of the same techniques will allow us to combine advantages of backscattering spectroscopy on continuous and pulsed sources in order to deliver μeV resolution in a very broad energy transfer range.

Achieving the full performance of highly efficient columns by optimizing conventional benchmark high-performance liquid chromatography instruments.

PubMed

Gritti, Fabrice; Sanchez, Carl A; Farkas, Tivadar; Guiochon, Georges

2010-04-30

A series of experiments and measurements demonstrate the importance of minimizing the extra-column band broadening contribution of the instrument used. The combination of several measures allowed the achievement of the full potential efficiency of three Kinetex-C(18) columns, using a conventional liquid chromatograph. The first measure consists in minimizing the extra-column volume of the instrument, without increasing much its back pressure contribution, by changing the needle seat volume, the inner diameter and length of the capillary connectors, and the volume of the detector cell of a standard instrument (Agilent 1100). The second measure consists in injecting a volume of weak eluent (less than half the elution strength of the mobile phase) right after the sample, before the sample had time to reach the column. Experimental results show that these changes could provide most of the resolution expected from the true column performance. After the changes were made, the resolutions of the 2.1 mm x 50 mm, 4.6 mm x 50 mm, and 4.6 mm x 100 mm Kinetex-C(18) columns for compounds having retention factors close to 1 were increased by about 180, 35, and 30%, respectively. The resolutions obtained are then similar to those measured with advanced instruments like the Agilent 1200, the Agilent 1290 Infinity HPLC, and the Acquity chromatographs. 2010 Elsevier B.V. All rights reserved.

Experimental characterization of a direct conversion amorphous selenium detector with thicker conversion layer for dual-energy contrast-enhanced breast imaging.

PubMed

Scaduto, David A; Tousignant, Olivier; Zhao, Wei

2017-08-01

Dual-energy contrast-enhanced imaging is being investigated as a tool to identify and localize angiogenesis in the breast, a possible indicator of malignant tumors. This imaging technique requires that x-ray images are acquired at energies above the k-shell binding energy of an appropriate radiocontrast agent. Iodinated contrast agents are commonly used for vascular imaging, and require x-ray energies greater than 33 keV. Conventional direct conversion amorphous selenium (a-Se) flat-panel imagers for digital mammography show suboptimal absorption efficiencies at these higher energies. We use spatial-frequency domain image quality metrics to evaluate the performance of a prototype direct conversion flat-panel imager with a thicker a-Se layer, specifically fabricated for dual-energy contrast-enhanced breast imaging. Imaging performance was evaluated in a prototype digital breast tomosynthesis (DBT) system. The spatial resolution, noise characteristics, detective quantum efficiency, and temporal performance of the detector were evaluated for dual-energy imaging for both conventional full-field digital mammography (FFDM) and DBT. The zero-frequency detective quantum efficiency of the prototype detector is improved by approximately 20% over the conventional detector for higher energy beams required for imaging with iodinated contrast agents. The effect of oblique entry of x-rays on spatial resolution does increase with increasing photoconductor thickness, specifically for the most oblique views of a DBT scan. Degradation of spatial resolution due to focal spot motion was also observed. Temporal performance was found to be comparable to conventional mammographic detectors. Increasing the a-Se thickness in direct conversion flat-panel imagers results in better performance for dual-energy contrast-enhanced breast imaging. The reduction in spatial resolution due to oblique entry of x-rays is appreciable in the most extreme clinically relevant cases, but may not profoundly affect reconstructed images due to the algorithms and filters employed. Degradation to projection domain spatial resolution is thus outweighed by the improvement in detective quantum efficiency for high-energy x-rays. © 2017 American Association of Physicists in Medicine.

Wedge-shaped slice-selective adiabatic inversion pulse for controlling temporal width of bolus in pulsed arterial spin labeling

PubMed Central

Guo, Jia; Buxton, Richard B.; Wong, Eric C.

2015-01-01

Purpose In pulsed arterial spin labeling (PASL) methods, arterial blood is labeled via inverting a slab with uniform thickness, resulting in different temporal widths of boluses in vessels with different flow velocities. This limits the temporal resolution and signal-to-noise ratio (SNR) efficiency gains in PASL-based methods intended for high temporal resolution and SNR efficiency, such as Turbo-ASL and Turbo-QUASAR. Theory and Methods A novel wedge-shaped (WS) adiabatic inversion pulse is developed by adding in-plane gradient pulses to a slice-selective (SS) adiabatic inversion pulse to linearly modulate the inversion thicknesses at different locations while maintaining the adiabatic properties of the original pulse. A hyperbolic secant (HS) based WS inversion pulse was implemented. Its performance was tested in simulations, phantom and human experiments, and compared to an SS HS inversion pulse. Results Compared to the SS inversion pulse, the WS inversion pulse is capable of inducing different inversion thicknesses at different locations. It can be adjusted to generate a uniform temporal width of boluses in arteries at locations with different flow velocities. Conclusion The WS inversion pulse can be used to control the temporal widths of labeled boluses in PASL experiments. This should benefit PASL experiments by maximizing labeling duty cycle, and improving temporal resolution and SNR efficiency. PMID:26451521

Fabrication of zeolitic imidazolate framework-8-methacrylate monolith composite capillary columns for fast gas chromatographic separation of small molecules.

PubMed

Yusuf, Kareem; Badjah-Hadj-Ahmed, Ahmed Yacine; Aqel, Ahmad; ALOthman, Zeid Abdullah

2015-08-07

A composite zeolitic imidazolate framework-8 (ZIF-8) with a butyl methacrylate-co-ethylene dimethacrylate (BuMA-co-EDMA) monolithic capillary column (33.5cm long×250μm i.d.) was fabricated to enhance the separation efficiency of methacrylate monoliths toward small molecules using conventional low-pressure gas chromatography in comparison with a neat butyl methacrylate-co-ethylene dimethacrylate (BuMA-co-EDMA) monolithic capillary column (33.5cm long×250μm i.d.). The addition of 10mgmL(-1) ZIF-8 micro-particles increased the BET surface area of BuMA-co-EDMA by 3.4-fold. A fast separation of five linear alkanes in 36s with high resolution (Rs≥1.3) was performed using temperature program. Isothermal separation of the same sample also showed a high efficiency (3315platesm(-1) for octane) at 0.89min. Moreover, the column was able to separate skeletal isomers, such as iso-octane/octane and 2-methyl octane/nonane. In addition, an iso-butane/iso-butylene gas mixture was separated at ambient temperature. Comparison with an open tubular TR-5MS column (30m long×250μm i.d.) revealed the superiority of the composite column in separating the five-membered linear alkane mixture with 4-5 times increase in efficiency and a total separation time of 0.89min instead of 4.67min. A paint thinner sample was fully separated using the composite column in 2.43min with a good resolution (Rs≥0.89). The perfect combination between the polymeric monolith, with its high permeability, and ZIF-8, with its high surface area and flexible 0.34nm pore openings, led to the fast separation of small molecules with high efficiency and opened a new horizon in GC applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Reduced Sampling Size with Nanopipette for Tapping-Mode Scanning Probe Electrospray Ionization Mass Spectrometry Imaging

PubMed Central

Kohigashi, Tsuyoshi; Otsuka, Yoichi; Shimazu, Ryo; Matsumoto, Takuya; Iwata, Futoshi; Kawasaki, Hideya; Arakawa, Ryuichi

2016-01-01

Mass spectrometry imaging (MSI) with ambient sampling and ionization can rapidly and easily capture the distribution of chemical components in a solid sample. Because the spatial resolution of MSI is limited by the size of the sampling area, reducing sampling size is an important goal for high resolution MSI. Here, we report the first use of a nanopipette for sampling and ionization by tapping-mode scanning probe electrospray ionization (t-SPESI). The spot size of the sampling area of a dye molecular film on a glass substrate was decreased to 6 μm on average by using a nanopipette. On the other hand, ionization efficiency increased with decreasing solvent flow rate. Our results indicate the compatibility between a reduced sampling area and the ionization efficiency using a nanopipette. MSI of micropatterns of ink on a glass and a polymer substrate were also demonstrated. PMID:28101441

Communication: Adaptive boundaries in multiscale simulations

NASA Astrophysics Data System (ADS)

Wagoner, Jason A.; Pande, Vijay S.

2018-04-01

Combined-resolution simulations are an effective way to study molecular properties across a range of length and time scales. These simulations can benefit from adaptive boundaries that allow the high-resolution region to adapt (change size and/or shape) as the simulation progresses. The number of degrees of freedom required to accurately represent even a simple molecular process can vary by several orders of magnitude throughout the course of a simulation, and adaptive boundaries react to these changes to include an appropriate but not excessive amount of detail. Here, we derive the Hamiltonian and distribution function for such a molecular simulation. We also design an algorithm that can efficiently sample the boundary as a new coordinate of the system. We apply this framework to a mixed explicit/continuum simulation of a peptide in solvent. We use this example to discuss the conditions necessary for a successful implementation of adaptive boundaries that is both efficient and accurate in reproducing molecular properties.

LSAH: a fast and efficient local surface feature for point cloud registration

NASA Astrophysics Data System (ADS)

Lu, Rongrong; Zhu, Feng; Wu, Qingxiao; Kong, Yanzi

2018-04-01

Point cloud registration is a fundamental task in high level three dimensional applications. Noise, uneven point density and varying point cloud resolutions are the three main challenges for point cloud registration. In this paper, we design a robust and compact local surface descriptor called Local Surface Angles Histogram (LSAH) and propose an effectively coarse to fine algorithm for point cloud registration. The LSAH descriptor is formed by concatenating five normalized sub-histograms into one histogram. The five sub-histograms are created by accumulating a different type of angle from a local surface patch respectively. The experimental results show that our LSAH is more robust to uneven point density and point cloud resolutions than four state-of-the-art local descriptors in terms of feature matching. Moreover, we tested our LSAH based coarse to fine algorithm for point cloud registration. The experimental results demonstrate that our algorithm is robust and efficient as well.

Dithering Digital Ripple Correlation Control for Photovoltaic Maximum Power Point Tracking

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

Barth, C; Pilawa-Podgurski, RCN

This study demonstrates a new method for rapid and precise maximum power point tracking in photovoltaic (PV) applications using dithered PWM control. Constraints imposed by efficiency, cost, and component size limit the available PWM resolution of a power converter, and may in turn limit the MPP tracking efficiency of the PV system. In these scenarios, PWM dithering can be used to improve average PWM resolution. In this study, we present a control technique that uses ripple correlation control (RCC) on the dithering ripple, thereby achieving simultaneous fast tracking speed and high tracking accuracy. Moreover, the proposed method solves some ofmore » the practical challenges that have to date limited the effectiveness of RCC in solar PV applications. We present a theoretical derivation of the principles behind dithering digital ripple correlation control, as well as experimental results that show excellent tracking speed and accuracy with basic hardware requirements.« less

Learning Low-Rank Decomposition for Pan-Sharpening With Spatial-Spectral Offsets.

PubMed

Yang, Shuyuan; Zhang, Kai; Wang, Min

2017-08-25

Finding accurate injection components is the key issue in pan-sharpening methods. In this paper, a low-rank pan-sharpening (LRP) model is developed from a new perspective of offset learning. Two offsets are defined to represent the spatial and spectral differences between low-resolution multispectral and high-resolution multispectral (HRMS) images, respectively. In order to reduce spatial and spectral distortions, spatial equalization and spectral proportion constraints are designed and cast on the offsets, to develop a spatial and spectral constrained stable low-rank decomposition algorithm via augmented Lagrange multiplier. By fine modeling and heuristic learning, our method can simultaneously reduce spatial and spectral distortions in the fused HRMS images. Moreover, our method can efficiently deal with noises and outliers in source images, for exploring low-rank and sparse characteristics of data. Extensive experiments are taken on several image data sets, and the results demonstrate the efficiency of the proposed LRP.

Quantum correlation enhanced super-resolution localization microscopy enabled by a fibre bundle camera

PubMed Central

Israel, Yonatan; Tenne, Ron; Oron, Dan; Silberberg, Yaron

2017-01-01

Despite advances in low-light-level detection, single-photon methods such as photon correlation have rarely been used in the context of imaging. The few demonstrations, for example of subdiffraction-limited imaging utilizing quantum statistics of photons, have remained in the realm of proof-of-principle demonstrations. This is primarily due to a combination of low values of fill factors, quantum efficiencies, frame rates and signal-to-noise characteristic of most available single-photon sensitive imaging detectors. Here we describe an imaging device based on a fibre bundle coupled to single-photon avalanche detectors that combines a large fill factor, a high quantum efficiency, a low noise and scalable architecture. Our device enables localization-based super-resolution microscopy in a non-sparse non-stationary scene, utilizing information on the number of active emitters, as gathered from non-classical photon statistics. PMID:28287167

Fast evaluation of solid harmonic Gaussian integrals for local resolution-of-the-identity methods and range-separated hybrid functionals.

PubMed

Golze, Dorothea; Benedikter, Niels; Iannuzzi, Marcella; Wilhelm, Jan; Hutter, Jürg

2017-01-21

An integral scheme for the efficient evaluation of two-center integrals over contracted solid harmonic Gaussian functions is presented. Integral expressions are derived for local operators that depend on the position vector of one of the two Gaussian centers. These expressions are then used to derive the formula for three-index overlap integrals where two of the three Gaussians are located at the same center. The efficient evaluation of the latter is essential for local resolution-of-the-identity techniques that employ an overlap metric. We compare the performance of our integral scheme to the widely used Cartesian Gaussian-based method of Obara and Saika (OS). Non-local interaction potentials such as standard Coulomb, modified Coulomb, and Gaussian-type operators, which occur in range-separated hybrid functionals, are also included in the performance tests. The speed-up with respect to the OS scheme is up to three orders of magnitude for both integrals and their derivatives. In particular, our method is increasingly efficient for large angular momenta and highly contracted basis sets.