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Sample records for large area negative

  1. Large-area flexible 3D optical negative index metamaterial formed by nanotransfer printing

    NASA Astrophysics Data System (ADS)

    Chanda, Debashis; Shigeta, Kazuki; Gupta, Sidhartha; Cain, Tyler; Carlson, Andrew; Mihi, Agustin; Baca, Alfred J.; Bogart, Gregory R.; Braun, Paul; Rogers, John A.

    2011-07-01

    Negative-index metamaterials (NIMs) are engineered structures with optical properties that cannot be obtained in naturally occurring materials. Recent work has demonstrated that focused ion beam and layer-by-layer electron-beam lithography can be used to pattern the necessary nanoscale features over small areas (hundreds of µm2) for metamaterials with three-dimensional layouts and interesting characteristics, including negative-index behaviour in the optical regime. A key challenge is in the fabrication of such three-dimensional NIMs with sizes and at throughputs necessary for many realistic applications (including lenses, resonators and other photonic components). We report a simple printing approach capable of forming large-area, high-quality NIMs with three-dimensional, multilayer formats. Here, a silicon wafer with deep, nanoscale patterns of surface relief serves as a reusable stamp. Blanket deposition of alternating layers of silver and magnesium fluoride onto such a stamp represents a process for `inking' it with thick, multilayer assemblies. Transfer printing this ink material onto rigid or flexible substrates completes the fabrication in a high-throughput manner. Experimental measurements and simulation results show that macroscale, three-dimensional NIMs (>75 cm2) nano-manufactured in this way exhibit a strong, negative index of refraction in the near-infrared spectral range, with excellent figures of merit.

  2. Isotropic Negative Area Compressibility over Large Pressure Range in Potassium Beryllium Fluoroborate and its Potential Applications in Deep Ultraviolet Region.

    PubMed

    Jiang, Xingxing; Luo, Siyang; Kang, Lei; Gong, Pifu; Yao, Wenjiao; Huang, Hongwei; Li, Wei; Huang, Rongjin; Wang, Wei; Li, Yanchun; Li, Xiaodong; Wu, Xiang; Lu, Peixiang; Li, Laifeng; Chen, Chuangtian; Lin, Zheshuai

    2015-09-01

    Isotropic negative area compressibility, which is very rare, is observed in KBBF and the related mechanism is investigated by combined high-pressure X-ray diffraction (XRD) experiments and first-principles calculations. The strong mechanical anisotropy leads to a large Poisson's ratio and high figure of merit for the acoustic-optics effect, giving KBBF potential applications as smart strain converters and deep-ultraviolet (DUV) acoustic-optic devices. PMID:26184364

  3. Large area LED package

    NASA Astrophysics Data System (ADS)

    Goullon, L.; Jordan, R.; Braun, T.; Bauer, J.; Becker, F.; Hutter, M.; Schneider-Ramelow, M.; Lang, K.-D.

    2015-03-01

    Solid state lighting using LED-dies is a rapidly growing market. LED-dies with the needed increasing luminous flux per chip area produce a lot of heat. Therefore an appropriate thermal management is required for general lighting with LEDdies. One way to avoid overheating and shorter lifetime is the use of many small LED-dies on a large area heat sink (down to 70 μm edge length), so that heat can spread into a large area while at the same time light also appears on a larger area. The handling with such small LED-dies is very difficult because they are too small to be picked with common equipment. Therefore a new concept called collective transfer bonding using a temporary carrier chip was developed. A further benefit of this new technology is the high precision assembly as well as the plane parallel assembly of the LED-dies which is necessary for wire bonding. It has been shown that hundred functional LED-dies were transferred and soldered at the same time. After the assembly a cost effective established PCB-technology was applied to produce a large-area light source consisting of many small LED-dies and electrically connected on a PCB-substrate. The top contacts of the LED-dies were realized by laminating an adhesive copper sheet followed by LDI structuring as known from PCB-via-technology. This assembly can be completed by adding converting and light forming optical elements. In summary two technologies based on standard SMD and PCB technology have been developed for panel level LED packaging up to 610x 457 mm2 area size.

  4. The Large Area Telescope

    SciTech Connect

    Michelson, Peter F.; /KIPAC, Menlo Park /Stanford U., HEPL

    2007-11-13

    The Large Area Telescope (LAT), one of two instruments on the Gamma-ray Large Area Space Telescope (GLAST) mission, is an imaging, wide field-of-view, high-energy pair-conversion telescope, covering the energy range from {approx}20 MeV to more than 300 GeV. The LAT is being built by an international collaboration with contributions from space agencies, high-energy particle physics institutes, and universities in France, Italy, Japan, Sweden, and the United States. The scientific objectives the LAT will address include resolving the high-energy gamma-ray sky and determining the nature of the unidentified gamma-ray sources and the origin of the apparently isotropic diffuse emission observed by EGRET; understanding the mechanisms of particle acceleration in celestial sources, including active galactic nuclei, pulsars, and supernovae remnants; studying the high-energy behavior of gamma-ray bursts and transients; using high-energy gamma-rays to probe the early universe to z {ge} 6; and probing the nature of dark matter. The components of the LAT include a precision silicon-strip detector tracker and a CsI(Tl) calorimeter, a segmented anticoincidence shield that covers the tracker array, and a programmable trigger and data acquisition system. The calorimeter's depth and segmentation enable the high-energy reach of the LAT and contribute significantly to background rejection. The aspect ratio of the tracker (height/width) is 0.4, allowing a large field-of-view and ensuring that nearly all pair-conversion showers initiated in the tracker will pass into the calorimeter for energy measurement. This paper includes a description of each of these LAT subsystems as well as a summary of the overall performance of the telescope.

  5. The negative relief of large river floodplains

    NASA Astrophysics Data System (ADS)

    Lewin, John; Ashworth, Philip J.

    2014-02-01

    Large floodplains have multiple and complex negative relief assemblages in which depressions fall below local or general floodplain surfaces at a variety of scales. The generation and dynamics of negative relief along major alluvial corridors are described and compared. Such depressions are significant for the storage and passage of surface waters, the creation of a range of riparian, wetland, lacustrine and flowing-water habitats, and the long-term accumulation of organic materials.

  6. Large area Czochralski silicon

    NASA Technical Reports Server (NTRS)

    Rea, S. N.; Gleim, P. S.

    1977-01-01

    The overall cost effectiveness of the Czochralski process for producing large-area silicon was determined. The feasibility of growing several 12 cm diameter crystals sequentially at 12 cm/h during a furnace run and the subsequent slicing of the ingot using a multiblade slurry saw were investigated. The goal of the wafering process was a slice thickness of 0.25 mm with minimal kerf. A slice + kerf of 0.56 mm was achieved on 12 cm crystal using both 400 grit B4C and SiC abrasive slurries. Crystal growth experiments were performed at 12 cm diameter in a commercially available puller with both 10 and 12 kg melts. Several modifications to the puller hoz zone were required to achieve stable crystal growth over the entire crystal length and to prevent crystallinity loss a few centimeters down the crystal. The maximum practical growth rate for 12 cm crystal in this puller design was 10 cm/h, with 12 to 14 cm/h being the absolute maximum range at which melt freeze occurred.

  7. Large area plasma source

    NASA Technical Reports Server (NTRS)

    Foster, John (Inventor); Patterson, Michael (Inventor)

    2008-01-01

    An all permanent magnet Electron Cyclotron Resonance, large diameter (e.g., 40 cm) plasma source suitable for ion/plasma processing or electric propulsion, is capable of producing uniform ion current densities at its exit plane at very low power (e.g., below 200 W), and is electrodeless to avoid sputtering or contamination issues. Microwave input power is efficiently coupled with an ionizing gas without using a dielectric microwave window and without developing a throat plasma by providing a ferromagnetic cylindrical chamber wall with a conical end narrowing to an axial entrance hole for microwaves supplied on-axis from an open-ended waveguide. Permanent magnet rings are attached inside the wall with alternating polarities against the wall. An entrance magnet ring surrounding the entrance hole has a ferromagnetic pole piece that extends into the chamber from the entrance hole to a continuing second face that extends radially across an inner pole of the entrance magnet ring.

  8. Beamlet deflection due to beamlet-beamlet interaction in a large-area multiaperture negative ion source for JT-60U

    SciTech Connect

    Kamada, M.; Hanada, M.; Ikeda, Y.; Grisham, L. R.; Jiang, W.

    2008-02-15

    The JT-60U negative ion source has been designed to produce high current beams of 22 A through grids of 1080 apertures (five segments with nine rows of 24 apertures). One of the key issues is to steer such a high current beam through the multiaperture grids in order to focus the overall beam envelope because the beamlet-beamlet interaction may deflect the outer beamlets outward due to unbalanced space charge repulsion. To clarify the beam deflection in the JT-60U negative ion source, the beamlet trajectory in a multiaperture ion source was calculated by a three-dimensional simulation code. The measured angles of the outmost beamlets were in agreement with the calculated results where space charge of the beamlets was taken into account. It is noticed that the deflection of the outermost beamlet due to the beamlet-beamlet interaction is saturated at 5.2 mrad outward for beamlets more than ten.

  9. Fermi's Large Area Telescope (LAT)

    NASA Video Gallery

    Fermi’s Large Area Telescope (LAT) is the spacecraft’s main scientificinstrument. This animation shows a gamma ray (purple) entering the LAT,where it is converted into an electron (red) and a...

  10. Progress on large area GEMs

    NASA Astrophysics Data System (ADS)

    Villa, Marco; Duarte Pinto, Serge; Alfonsi, Matteo; Brock, Ian; Croci, Gabriele; David, Eric; de Oliveira, Rui; Ropelewski, Leszek; Taureg, Hans; van Stenis, Miranda

    2011-02-01

    The Gas Electron Multiplier (GEM) manufacturing technique has recently evolved to allow the production of large area GEMs. A novel approach based on single mask photolithography eliminates the mask alignment issue, which limits the dimensions in the traditional double mask process. Moreover, a splicing technique overcomes the limited width of the raw material. Stretching and handling issues in large area GEMs have also been addressed. Using the new improvements it was possible to build a prototype triple-GEM detector of ˜2000 cm2 active area, aimed at an application for the TOTEM T1 upgrade. Further refinements of the single mask technique allow great control over the shape of the GEM holes and the size of the rims, which can be tuned as needed. In this framework, simulation studies can help to understand the GEM behavior depending on the hole shape.

  11. Large area pulsed solar simulator

    NASA Technical Reports Server (NTRS)

    Kruer, Mark A. (Inventor)

    1999-01-01

    An advanced solar simulator illuminates the surface a very large solar array, such as one twenty feet by twenty feet in area, from a distance of about twenty-six feet with an essentially uniform intensity field of pulsed light of an intensity of one AMO, enabling the solar array to be efficiently tested with light that emulates the sun. Light modifiers sculpt a portion of the light generated by an electrically powered high power Xenon lamp and together with direct light from the lamp provide uniform intensity illumination throughout the solar array, compensating for the square law and cosine law reduction in direct light intensity, particularly at the corner locations of the array. At any location within the array the sum of the direct light and reflected light is essentially constant.

  12. Large area CMOS image sensors

    NASA Astrophysics Data System (ADS)

    Turchetta, R.; Guerrini, N.; Sedgwick, I.

    2011-01-01

    CMOS image sensors, also known as CMOS Active Pixel Sensors (APS) or Monolithic Active Pixel Sensors (MAPS), are today the dominant imaging devices. They are omnipresent in our daily life, as image sensors in cellular phones, web cams, digital cameras, ... In these applications, the pixels can be very small, in the micron range, and the sensors themselves tend to be limited in size. However, many scientific applications, like particle or X-ray detection, require large format, often with large pixels, as well as other specific performance, like low noise, radiation hardness or very fast readout. The sensors are also required to be sensitive to a broad spectrum of radiation: photons from the silicon cut-off in the IR down to UV and X- and gamma-rays through the visible spectrum as well as charged particles. This requirement calls for modifications to the substrate to be introduced to provide optimized sensitivity. This paper will review existing CMOS image sensors, whose size can be as large as a single CMOS wafer, and analyse the technical requirements and specific challenges of large format CMOS image sensors.

  13. Time evolution of negative ion profile in a large cesiated negative ion source applicable to fusion reactors.

    PubMed

    Yoshida, M; Hanada, M; Kojima, A; Kashiwagi, M; Umeda, N; Hiratsuka, J; Ichikawa, M; Watanabe, K; R Grisham, L; Tsumori, K; Kisaki, M

    2016-02-01

    To understand the physics of the cesium (Cs) recycling in the large Cs-seeded negative ion sources relevant to ITER and JT-60SA with ion extraction area of 45-60 cm × 110-120 cm, the time evolution of the negative ion profile was precisely measured in JT-60SA where the ion extraction area is longitudinally segmented into 5. The Cs was seeded from the oven at 180 °C to the ion source. After 1 g of Cs input, surface production of the negative ions appeared only in the central segment where a Cs nozzle was located. Up to 2 g of Cs, the negative ion profile was longitudinally expanded over full ion extraction area. The measured time evolution of the negative ion profile has the similar tendency of distribution of the Cs atoms that is calculated. From the results, it is suggested that Cs atom distribution is correlated with the formation of the negative ion profile. PMID:26932026

  14. Time evolution of negative ion profile in a large cesiated negative ion source applicable to fusion reactors

    NASA Astrophysics Data System (ADS)

    Yoshida, M.; Hanada, M.; Kojima, A.; Kashiwagi, M.; Umeda, N.; Hiratsuka, J.; Ichikawa, M.; Watanabe, K.; R. Grisham, L.; Tsumori, K.; Kisaki, M.

    2016-02-01

    To understand the physics of the cesium (Cs) recycling in the large Cs-seeded negative ion sources relevant to ITER and JT-60SA with ion extraction area of 45-60 cm × 110-120 cm, the time evolution of the negative ion profile was precisely measured in JT-60SA where the ion extraction area is longitudinally segmented into 5. The Cs was seeded from the oven at 180 °C to the ion source. After 1 g of Cs input, surface production of the negative ions appeared only in the central segment where a Cs nozzle was located. Up to 2 g of Cs, the negative ion profile was longitudinally expanded over full ion extraction area. The measured time evolution of the negative ion profile has the similar tendency of distribution of the Cs atoms that is calculated. From the results, it is suggested that Cs atom distribution is correlated with the formation of the negative ion profile.

  15. H3O+ tetrahedron induction in large negative linear compressibility

    PubMed Central

    Wang, Hui; Feng, Min; Wang, Yu-Fang; Gu, Zhi-Yuan

    2016-01-01

    Despite the rarity, large negative linear compressibility (NLC) was observed in metal-organic framework material Zn(HO3PC4H8PO3H)∙2H2O (ZAG-4) in experiment. We find a unique NLC mechanism in ZAG-4 based on first-principle calculations. The key component to realize its large NLC is the deformation of H3O+ tetrahedron. With pressure increase, the oxygen apex approaches and then is inserted into the tetrahedron base (hydrogen triangle). The tetrahedron base subsequently expands, which results in the b axis expansion. After that, the oxygen apex penetrates the tetrahedron base and the b axis contracts. The negative and positive linear compressibility is well reproduced by the hexagonal model and ZAG-4 is the first MOFs evolving from non re-entrant to re-entrant hexagon framework with pressure increase. This gives a new approach to explore and design NLC materials. PMID:27184726

  16. H3O+ tetrahedron induction in large negative linear compressibility

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Feng, Min; Wang, Yu-Fang; Gu, Zhi-Yuan

    2016-05-01

    Despite the rarity, large negative linear compressibility (NLC) was observed in metal-organic framework material Zn(HO3PC4H8PO3H)•2H2O (ZAG-4) in experiment. We find a unique NLC mechanism in ZAG-4 based on first-principle calculations. The key component to realize its large NLC is the deformation of H3O+ tetrahedron. With pressure increase, the oxygen apex approaches and then is inserted into the tetrahedron base (hydrogen triangle). The tetrahedron base subsequently expands, which results in the b axis expansion. After that, the oxygen apex penetrates the tetrahedron base and the b axis contracts. The negative and positive linear compressibility is well reproduced by the hexagonal model and ZAG-4 is the first MOFs evolving from non re-entrant to re-entrant hexagon framework with pressure increase. This gives a new approach to explore and design NLC materials.

  17. H3O(+) tetrahedron induction in large negative linear compressibility.

    PubMed

    Wang, Hui; Feng, Min; Wang, Yu-Fang; Gu, Zhi-Yuan

    2016-01-01

    Despite the rarity, large negative linear compressibility (NLC) was observed in metal-organic framework material Zn(HO3PC4H8PO3H)∙2H2O (ZAG-4) in experiment. We find a unique NLC mechanism in ZAG-4 based on first-principle calculations. The key component to realize its large NLC is the deformation of H3O(+) tetrahedron. With pressure increase, the oxygen apex approaches and then is inserted into the tetrahedron base (hydrogen triangle). The tetrahedron base subsequently expands, which results in the b axis expansion. After that, the oxygen apex penetrates the tetrahedron base and the b axis contracts. The negative and positive linear compressibility is well reproduced by the hexagonal model and ZAG-4 is the first MOFs evolving from non re-entrant to re-entrant hexagon framework with pressure increase. This gives a new approach to explore and design NLC materials. PMID:27184726

  18. Increased tornado hazard in large metropolitan areas

    NASA Astrophysics Data System (ADS)

    Cusack, Stephen

    2014-11-01

    The tornado climate was compared between large metropolitan areas and neighbouring non-metro cities using modern tornado reports in the Storm Prediction Center (SPC) archives. Twenty large metro areas in the higher-risk region of the U.S. were used to boost sample sizes hence robustness of results. Observational biases were minimised by using the most densely populated zips. The analysis found 50% greater tornado frequency and a thicker-tailed severity distribution in metro areas compared to the non-metro cities. These differences are significant at the 1% level. Regarding tornado frequency, the primary question is whether the raised occurrence rates in metro areas are due to observation biases or real differences in tornado climate. Past studies found no relative biases at the population densities used here, whereas there are two potential urban drivers of tornadogenesis. First, the urban heat island raises the storm severity above and downwind of main urban areas, as recorded in precipitation and lightning datasets. Second, the increased surface roughness over metro areas raises low-level shear which in turn has been found to be favourable for tornadogenesis. Modification of convective storms over large metro areas is the more plausible explanation of raised tornado frequency. The drivers of a thicker-tailed tornado severity distribution in metro areas are less certain. Potential causes include: increased debris-loading in metro tornadoes; modification of storms' lower boundary layer by increased surface roughness in metro areas; the reduced density of damage indicators in non-metro cities.

  19. Large area damage testing of optics

    SciTech Connect

    Sheehan, L.; Kozlowski, M.; Stolz, C.

    1996-04-26

    The damage threshold specifications for the National Ignition Facility will include a mixture of standard small-area tests and new large-area tests. During our studies of laser damage and conditioning processes of various materials we have found that some damage morphologies are fairly small and this damage does not grow with further illumination. This type of damage might not be detrimental to the laser performance. We should therefore assume that some damage can be allowed on the optics, but decide on a maximum damage allowance of damage. A new specification of damage threshold termed {open_quotes}functional damage threshold{close_quotes} was derived. Further correlation of damage size and type to system performance must be determined in order to use this measurement, but it is clear that it will be a large factor in the optics performance specifications. Large-area tests have verified that small-area testing is not always sufficient when the optic in question has defect-initiated damage. This was evident for example on sputtered polarizer and mirror coatings where the defect density was low enough that the features could be missed by standard small- area testing. For some materials, the scale-length at which damage non-uniformities occur will effect the comparison of small-area and large-area tests. An example of this was the sub-aperture tests on KD*P crystals on the Beamlet test station. The tests verified the large-area damage threshold to be similar to that found when testing a small-area. Implying that for this KD*P material, the dominate damage mechanism is of sufficiently small scale-length that small-area testing is capable of determining the threshold. The Beamlet test station experiments also demonstrated the use of on-line laser conditioning to increase the crystals damage threshold.

  20. Predicting Positive and Negative Relationships in Large Social Networks

    PubMed Central

    Wang, Guan-Nan; Gao, Hui; Chen, Lian; Mensah, Dennis N. A.; Fu, Yan

    2015-01-01

    In a social network, users hold and express positive and negative attitudes (e.g. support/opposition) towards other users. Those attitudes exhibit some kind of binary relationships among the users, which play an important role in social network analysis. However, some of those binary relationships are likely to be latent as the scale of social network increases. The essence of predicting latent binary relationships have recently began to draw researchers' attention. In this paper, we propose a machine learning algorithm for predicting positive and negative relationships in social networks inspired by structural balance theory and social status theory. More specifically, we show that when two users in the network have fewer common neighbors, the prediction accuracy of the relationship between them deteriorates. Accordingly, in the training phase, we propose a segment-based training framework to divide the training data into two subsets according to the number of common neighbors between users, and build a prediction model for each subset based on support vector machine (SVM). Moreover, to deal with large-scale social network data, we employ a sampling strategy that selects small amount of training data while maintaining high accuracy of prediction. We compare our algorithm with traditional algorithms and adaptive boosting of them. Experimental results of typical data sets show that our algorithm can deal with large social networks and consistently outperforms other methods. PMID:26075404

  1. Large Area Synthesis of 2D Materials

    NASA Astrophysics Data System (ADS)

    Vogel, Eric

    Transition metal dichalcogenides (TMDs) have generated significant interest for numerous applications including sensors, flexible electronics, heterostructures and optoelectronics due to their interesting, thickness-dependent properties. Despite recent progress, the synthesis of high-quality and highly uniform TMDs on a large scale is still a challenge. In this talk, synthesis routes for WSe2 and MoS2 that achieve monolayer thickness uniformity across large area substrates with electrical properties equivalent to geological crystals will be described. Controlled doping of 2D semiconductors is also critically required. However, methods established for conventional semiconductors, such as ion implantation, are not easily applicable to 2D materials because of their atomically thin structure. Redox-active molecular dopants will be demonstrated which provide large changes in carrier density and workfunction through the choice of dopant, treatment time, and the solution concentration. Finally, several applications of these large-area, uniform 2D materials will be described including heterostructures, biosensors and strain sensors.

  2. Large Area Sputter Coating on Glass

    NASA Astrophysics Data System (ADS)

    Katayama, Yoshihito

    Large glass has been used for commercial buildings, housings and vehicles for many years. Glass size for flat displays is getting larger and larger. The glass for the 8th generation is more than 5 m2 in area. Demand of the large glass is increasing not only in these markets but also in a solar cell market growing drastically. Therefore, large area coating is demanded to plus something else on glass more than ever. Sputtering and pyrolysis are the major coating methods on large glass today. Sputtering process is particularly popular because it can deposit a wide variety of materials in good coating uniformity on the glass. This paper describes typical industrial sputtering system and recent progress in sputtering technology. It also shows typical coated glass products in architectural, automotive and display fields and comments on their functions, film stacks and so on.

  3. Method of Making Large Area Nanostructures

    NASA Technical Reports Server (NTRS)

    Marks, Alvin M.

    1995-01-01

    A method which enables the high speed formation of nanostructures on large area surfaces is described. The method uses a super sub-micron beam writer (Supersebter). The Supersebter uses a large area multi-electrode (Spindt type emitter source) to produce multiple electron beams simultaneously scanned to form a pattern on a surface in an electron beam writer. A 100,000 x 100,000 array of electron point sources, demagnified in a long electron beam writer to simultaneously produce 10 billion nano-patterns on a 1 meter squared surface by multi-electron beam impact on a 1 cm squared surface of an insulating material is proposed.

  4. Large area space solar cell assemblies

    NASA Technical Reports Server (NTRS)

    Spitzer, M. B.; Nowlan, M. J.

    1982-01-01

    Development of a large area space solar cell assembly is presented. The assembly consists of an ion implanted silicon cell and glass cover. The important attributes of fabrication are (1) use of a back surface field which is compatible with a back surface reflector, and (2) integration of coverglass application and call fabrication.

  5. The Large Area Crop Inventory Experiment (LACIE)

    NASA Technical Reports Server (NTRS)

    Macdonald, R. B.

    1976-01-01

    A Large Area Crop Inventory Experiment (LACIE) was undertaken to prove out an economically important application of remote sensing from space. The experiment focused upon determination of wheat acreages in the U.S. Great Plains and upon the development and testing of yield models. The results and conclusions are presented.

  6. GLAST Large Area Telescope Multiwavelength Planning

    SciTech Connect

    Reimer, O.; Michelson, P.F.; Cameron, R.A.; Digel, S.W.; Thompson, D.J.; Wood, K.S.

    2007-01-03

    Gamma-ray astrophysics depends in many ways on multiwavelength studies. The Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) Collaboration has started multiwavelength planning well before the scheduled 2007 launch of the observatory. Some of the high-priority multiwavelength needs include: (1) availability of contemporaneous radio and X-ray timing of pulsars; (2) expansion of blazar catalogs, including redshift measurements; (3) improved observations of molecular clouds, especially at high galactic latitudes; (4) simultaneous broad-band blazar monitoring; (5) characterization of gamma-ray transients, including gamma ray bursts; (6) radio, optical, X-ray and TeV counterpart searches for reliable and effective sources identification and characterization. Several of these activities are needed to be in place before launch.

  7. GLAST Large Area Telescope Multiwavelength Planning

    NASA Technical Reports Server (NTRS)

    Reimer, O.; Michelson, P. F.; Cameron, R. A.; Digel, S. W.; Thompson, D. J.; Wood, K. S.

    2007-01-01

    Gamma-ray astrophysics depends in many ways on multiwavelength studies. The Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) Collaboration has started multiwavelength planning well before the scheduled 2007 launch of the observatory. Some of the high-priority multiwavelength needs include: (1) availability of contemporaneous radio and X-ray timing of pulsars; (2) expansion of blazar catalogs, including redshift measurements; (3) improved observations of molecular clouds, especially at high galactic latitudes; (4) simultaneous broad-spectrum blazar monitoring; (5) characterization of gamma-ray transients, including gamma ray bursts; (6) radio, optical, X-ray and TeV counterpart searches for reliable and effective sources identification and characterization. Several of these activities are needed to be in place before launch.

  8. GLAST Large Area Telescope Multiwavelength Planning

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Cameron, R. A.; Digel, S. W.; Wood, K. S.

    2006-01-01

    Because gamma-ray astrophysics depends in many ways on multiwavelength studies, the GLAST Large Area Telescope (LAT) Collaboration has started multiwavelength planning well before the scheduled 2007 launch of the observatory. Some of the high-priority needs include: (1) radio and X-ray timing of pulsars; (2) expansion of blazar catalogs, including redshift measurements (3) improved observations of molecular clouds, especially at high galactic latitudes; (4) simultaneous broad-spectrum blazar flare measurements; (5) characterization of gamma-ray transients, including gamma ray bursts; (6) radio, optical, X-ray and TeV counterpart searches for unidentified gamma-ray sources. Work on the first three of these activities is needed before launch. The GLAST Large Area Telescope is an international effort, with U.S. funding provided by the Department of Energy and NASA.

  9. Large-area thin-film modules

    NASA Technical Reports Server (NTRS)

    Tyan, Y. S.; Perez-Albuerne, E. A.

    1985-01-01

    The low cost potential of thin film solar cells can only be fully realized if large area modules can be made economically with good production yields. This paper deals with two of the critical challenges. A scheme is presented which allows the simple, economical realization of the long recognized, preferred module structure of monolithic integration. Another scheme reduces the impact of shorting defects and, as a result, increases the production yields. Analytical results demonstrating the utilization and advantages of such schemes are discussed.

  10. Large-Area Vacuum Ultraviolet Sensors

    NASA Technical Reports Server (NTRS)

    Aslam, Shahid; Franz, David

    2012-01-01

    Pt/(n-doped GaN) Schottky-barrier diodes having active areas as large as 1 cm square have been designed and fabricated as prototypes of photodetectors for the vacuum ultraviolet portion (wavelengths approximately equal 200 nm) of the solar spectrum. In addition to having adequate sensitivity to photons in this wavelength range, these photodetectors are required to be insensitive to visible and infrared components of sunlight and to have relatively low levels of dark current.

  11. Large Area Printing of Organic Transistors

    NASA Astrophysics Data System (ADS)

    Blanchet, Graciela B.; Rogers, J. A.; Lefenfeld, M.; Fincher, C. R.; Loo, Jueh-Lin

    2003-03-01

    Organic electronic systems offer the advantage of lightweight, mechanical flexibility and large area coverage at potentially lower manufacturing cost. Although the production of functioning plastic transistors using approaches such as ink jet, screen printing and stamping, has been described in the literature, no one-transistor layer has yet been fabricated using a technique appropriate for their commercial ization. The solution processability of many organics may ultimately allow for the printing of electronic devices in a printing press at high speeds and in a reel to reel configuration. However, designing chemically compatible solutions to be printed sequentially represents a significant technical barrier to achieving all-printed plastic electronic systems. The work presented here represents a step change in the fabrication of organic electronic devices. We introduce thermal transfer, a non-lithographic technique that enables printing multi-layer electronics devices via a dry (i.e. solvent-less) additive process. This high-speed method is capable of patterning a range of organic materials over large areas ( 1 m2 ) with micron dimensions and excellent electrical performance. The 0.5 m2 transistor array backplane printed via thermal transfer represent the most advanced demonstration of a novel printing technology applied to the fabrication of large area integrated electronic devices. Dry transfer printing may provide a practical route to realizing the benefits of plastic materials for electronics.

  12. GLAST Large Area Telescope Multiwavelength Opportunities

    NASA Technical Reports Server (NTRS)

    Thompson, David

    2008-01-01

    The Gamma-ray Large Area Space Telescope (GLAST) is scheduled for launch this year. Because the GLAST Large Area Telescope (LAT) has a huge field of view and the GLAST Observatory will be operated in scanning mode, it will survey the entire sky daily. The GLAST Mission and the LAT Collaboration invite cooperative efforts from theorists and observers at all wavelengths to help optimize the science. Possible topics include: (1) Blazars: These Active Galactic Nuclei are expected to be a major source class for LAT. Identifying new blazars, monitoring their variability, and joining programs to carry out planned or Target of Opportunity multiwavelength campaigns will all be important activities. The study of AGN gamma-ray jets can help link the accretion processes close to the black hole with the large-scale interaction of the AGN with its environment. (2) Unidentified Gamma-ray Sources: Modeling of possible gamma-ray sources is important to establish testable hypotheses. New gamma-ray sources need first to be identified with known objects by position, spectrum, or time variability, and then multiwavelength studies can be used to explore the astrophysical implications of high-energy radiation from these sources. The LAT team is committed to releasing a preliminary source list about six months after the start of science operations.

  13. Negative-pressure solar dryer for large round alfalfa bales

    SciTech Connect

    Frisby, J.C.; George, R.M.; Everett, J.T.

    1985-01-01

    A single-bale, portable, negative-pressure solar dryer was constructed and tested. It was found that design criteria established on pressurized systems could be used for negative-pressure systems. Hay packaged at 40 percent moisture content dried more uniformly if baled with a fixed-chamber baler.

  14. The Large Area Pulsed Solar Simulator (LAPSS)

    NASA Technical Reports Server (NTRS)

    Mueller, R. L.

    1993-01-01

    A Large Area Pulsed Solar Simulator (LAPSS) has been installed at JPL. It is primarily intended to be used to illuminate and measure the electrical performance of photovoltaic devices. The simulator, originally manufactured by Spectrolab, Sylmar, California, occupies an area measuring about 3 meters wide by 12 meters long. The data acquisition and data processing subsystems have been modernized. Tests on the LAPSS performance resulted in better than +/- 2 percent uniformity of irradiance at the test plane and better than +/- 0.3 percent measurement repeatability after warm-up. Glass absorption filters are used to reduce the level of ultraviolet light emitted from the xenon flash lamps. This provides a close match to standard airmass zero and airmass 1.5 spectral irradiance distributions. The 2 millisecond light pulse prevents heating of the device under test, resulting in more reliable temperature measurements. Overall, excellent electrical performance measurements have been made of many different types and sizes of photovoltaic devices.

  15. Timing characteristics of Large Area Picosecond Photodetectors

    NASA Astrophysics Data System (ADS)

    Adams, B. W.; Elagin, A.; Frisch, H. J.; Obaid, R.; Oberla, E.; Vostrikov, A.; Wagner, R. G.; Wang, J.; Wetstein, M.

    2015-09-01

    The LAPPD Collaboration was formed to develop ultrafast large-area imaging photodetectors based on new methods for fabricating microchannel plates (MCPs). In this paper we characterize the time response using a pulsed, sub-picosecond laser. We observe single-photoelectron time resolutions of a 20 cm × 20 cm MCP consistently below 70 ps, spatial resolutions of roughly 500 μm, and median gains higher than 107. The RMS measured at one particular point on an LAPPD detector is 58 ps, with ± 1σ of 47 ps. The differential time resolution between the signal reaching the two ends of the delay line anode is measured to be 5.1 ps for large signals, with an asymptotic limit falling below 2 ps as noise-over-signal approaches zero.

  16. Large area position sensitive β-detector

    NASA Astrophysics Data System (ADS)

    Vaintraub, S.; Hass, M.; Edri, H.; Morali, N.; Segal, T.

    2015-03-01

    A new conceptual design of a large area electron detector, which is position and energy sensitive, was developed. This detector is designed for beta decay energies up to 4 MeV, but in principle can be re-designed for higher energies. The detector incorporates one large plastic scintillator and, in general, a limited number of photomultipliers (7 presently). The current setup was designed and constructed after an extensive Geant4 simulation study. By comparison of a single hit light distribution between the various photomultipliers to a pre-measured accurate position-response map, the anticipated position resolution is around 5 mm. The first benchmark experiments have been conducted in order to calibrate and confirm the position resolution of the detector. The new method, results of the first test experiments and comparison to simulations are presented.

  17. Timing Characteristics of Large Area Picosecond Photodetectors

    SciTech Connect

    Adams, Bernhard W.; Elagin, Andrey L.; Frisch, H.; Obaid, Razib; Oberla, E; Vostrikov, Alexander; Wagner, Robert G.; Wang, Jingbo; Wetstein, Matthew J.; Northrop, R

    2015-09-21

    The LAPPD Collaboration was formed to develop ultralast large-area imaging photodetectors based on new methods for fabricating microchannel plates (MCPs). In this paper we characterize the time response using a pulsed, sub picosecond laser. We observe single photoelectron time resolutions of a 20 cm x 20 cm MCP consistently below 70 ps, spatial resolutions of roughly 500 pm, and median gains higher than 10(7). The RMS measured at one particular point on an LAPPD detector is 58 ps, with in of 47 ps. The differential time resolution between the signal reaching the two ends of the delay line anode is measured to be 5.1 ps for large signals, with an asymptotic limit falling below 2 ps as noise-over-signal approaches zero.

  18. Excimer lasers drive large-area microprocessing

    NASA Astrophysics Data System (ADS)

    Delmdahl, Ralph; Tapié, Jean-Luc

    2012-09-01

    Excimer lasers emitting in the UV to far UV region are by nature the laser sources enabling the highest optical resolution and strongest material-photon interaction. At the same time, excimer lasers deliver unmatched UV pulse energies and output powers up to the kilowatt range. Thus, they are the key to fast and effective large area processing of smallest structures with micron precision. As a consequence, excimer lasers are the UV technology of choice when it comes to high-performance microstructuring with unsurpassed quality and process repeatability in applications such as drilling advanced ink jet nozzles or patterning biomedical sensor structures.

  19. Large Area X-Ray Spectroscopy Mission

    NASA Technical Reports Server (NTRS)

    Tananbaum, H.

    1997-01-01

    The Large Area X-ray Spectroscopy (LAXS) mission concept study continues to evolve strongly following the merging of the LAXS mission with the Next Generation X-ray Observatory (NGXO, PI: Nick White) into the re-named High Throughput X-ray Spectroscopy (HTXS) Mission. HTXS retains key elements of the LAXS proposal, including the use of multiple satellites for risk-reduction and cost savings. A key achievement of the program has been the recommendation by the Structure and Evolution of the Universe (SEUS) (April 1997) for a new start for the HTXS mission in the 2000-2004 timeframe.

  20. Large area cold plasma applicator for decontamination

    NASA Astrophysics Data System (ADS)

    Konesky, G. A.

    2008-04-01

    Cold plasma applicators have been used in the Medical community for several years for uses ranging from hemostasis ("stop bleeding") to tumor removal. An added benefit of this technology is enhanced wound healing by the destruction of infectious microbial agents without damaging healthy tissue. The beam is typically one millimeter to less than a centimeter in diameter. This technology has been adapted and expanded to large area applicators of potentially a square meter or more. Decontamination applications include both biological and chemical agents, and assisting in the removal of radiological agents, with minimal or no damage to the contaminated substrate material. Linear and planar multiemitter array plasma applicator design and operation is discussed.

  1. The Large Area Pulsed Solar Simulator (LAPSS)

    NASA Technical Reports Server (NTRS)

    Mueller, R. L.

    1994-01-01

    The Large Area Pulsed Solar Simulator (LAPSS) has been installed at JPL. It is primarily intended to be used to illuminate and measure the electrical performance of photovoltaic devices. The simulator, originally manufactured by Spectrolab, Sylmar, CA, occupies an area measuring about 3 m wide x 12 m long. The data acquisition and data processing subsystems have been modernized. Tests on the LAPSS performance resulted in better than plus or minus 2 percent uniformity of irradiance at the test plane and better than plus or minus 0.3 percent measurement repeatability after warm-up. Glass absorption filters reduce the ultraviolet light emitted from the xenon flash lamps. This results in a close match to three different standard airmass zero and airmass 1.5 spectral irradiances. The 2-ms light pulse prevents heating of the device under test, resulting in more reliable temperature measurements. Overall, excellent electrical performance measurements have been made of many different types and sizes of photovoltaic devices. Since the original printing of this publication, in 1993, the LAPSS has been operational and new capabilities have been added. This revision includes a new section relating to the installation of a method to measure the I-V curve of a solar cell or array exhibiting a large effective capacitance. Another new section has been added relating to new capabilities for plotting single and multiple I-V curves, and for archiving the I-V data and test parameters. Finally, a section has been added regarding the data acquisition electronics calibration.

  2. Electrohydrodynamically driven large-area liquid ion sources

    DOEpatents

    Pregenzer, Arian L.

    1988-01-01

    A large-area liquid ion source comprises means for generating, over a large area of the surface of a liquid, an electric field of a strength sufficient to induce emission of ions from a large area of said liquid. Large areas in this context are those distinct from emitting areas in unidimensional emitters.

  3. The CLAS12 large area RICH detector

    SciTech Connect

    M. Contalbrigo, E. Cisbani, P. Rossi

    2011-05-01

    A large area RICH detector is being designed for the CLAS12 spectrometer as part of the 12 GeV upgrade program of the Jefferson Lab Experimental Hall-B. This detector is intended to provide excellent hadron identification from 3 GeV/c up to momenta exceeding 8 GeV/c and to be able to work at the very high design luminosity-up to 1035 cm2 s-1. Detailed feasibility studies are presented for two types of radiators, aerogel and liquid C6F14 freon, in conjunction with a highly segmented light detector in the visible wavelength range. The basic parameters of the RICH are outlined and the resulting performances, as defined by preliminary simulation studies, are reported.

  4. Large Area Lunar Dust Flux Measurement Instrument

    NASA Technical Reports Server (NTRS)

    Corsaro, R.; Giovane, F.; Liou, Jer-Chyi; Burchell, M.; Stansbery, Eugene; Lagakos, N.

    2009-01-01

    The instrument under development is designed to characterize the flux and size distribution of the lunar micrometeoroid and secondary ejecta environment. When deployed on the lunar surface, the data collected will benefit fundamental lunar science as well as enabling more reliable impact risk assessments for human lunar exploration activities. To perform this task, the instrument requirements are demanding. It must have as large a surface area as possible to sample the very sparse population of the larger potentially damage-inducing micrometeorites. It must also have very high sensitivity to enable it to measure the flux of small (<10 micron) micrometeorite and secondary ejecta dust particles. To be delivered to the lunar surface, it must also be very low mass, rugged and stow compactly. The instrument designed to meet these requirements is called FOMIS. It is a large-area thin film under tension (i.e. a drum) with multiple fiber optic displacement (FOD) sensors to monitor displacements of the film. This sensor was chosen since it can measure displacements over a wide dynamic range: 1 cm to sub-Angstrom. A prototype system was successfully demonstrated using the hypervelocity impact test facility at the University of Kent (Canterbury, UK). Based on these results, the prototype system can detect hypervelocity (approx.5 km/s) impacts by particles as small as 2 microns diameter. Additional tests using slow speeds find that it can detect secondary ejecta particles (which do not penetrate the film) with momentums as small as 15 pico-gram 100m/s, or nominally 5 microns diameter at 100 m/s.

  5. Fermi Large Area Telescope Second Source Catalog

    NASA Astrophysics Data System (ADS)

    Nolan, P. L.; Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Belfiore, A.; Bellazzini, R.; Berenji, B.; Bignami, G. F.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Bonnell, J.; Borgland, A. W.; Bottacini, E.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Campana, R.; Cañadas, B.; Cannon, A.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Ceccanti, M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chipaux, R.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Corbet, R.; Cutini, S.; D'Ammando, F.; Davis, D. S.; de Angelis, A.; DeCesar, M. E.; DeKlotz, M.; De Luca, A.; den Hartog, P. R.; de Palma, F.; Dermer, C. D.; Digel, S. W.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Dumora, D.; Enoto, T.; Escande, L.; Fabiani, D.; Falletti, L.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Fortin, P.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Iafrate, G.; Itoh, R.; Jóhannesson, G.; Johnson, R. P.; Johnson, T. E.; Johnson, A. S.; Johnson, T. J.; Kamae, T.; Katagiri, H.; Kataoka, J.; Katsuta, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocevski, D.; Kuss, M.; Lande, J.; Landriu, D.; Latronico, L.; Lemoine-Goumard, M.; Lionetto, A. M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Marelli, M.; Massaro, E.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Minuti, M.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Mongelli, M.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-Godo, M.; Norris, J. P.; Nuss, E.; Nymark, T.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Perkins, J. S.; Pesce-Rollins, M.; Pierbattista, M.; Pinchera, M.; Piron, F.; Pivato, G.; Porter, T. A.; Racusin, J. L.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rochester, L. S.; Romani, R. W.; Roth, M.; Rousseau, R.; Ryde, F.; Sadrozinski, H. F.-W.; Salvetti, D.; Sanchez, D. A.; Saz Parkinson, P. M.; Sbarra, C.; Scargle, J. D.; Schalk, T. L.; Sgrò, C.; Shaw, M. S.; Shrader, C.; Siskind, E. J.; Smith, D. A.; Spandre, G.; Spinelli, P.; Stephens, T. E.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Tinebra, F.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vandenbroucke, J.; Van Etten, A.; Van Klaveren, B.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Wallace, E.; Wang, P.; Werner, M.; Winer, B. L.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.; Zimmer, S.

    2012-04-01

    We present the second catalog of high-energy γ-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24 month period. The second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in five energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 MeV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely γ-ray-producing source classes. We dedicate this paper to the memory of our colleague Patrick Nolan, who died on 2011 November 6. His career spanned much of the history of high-energy astronomy from space and his work on the Large Area Telescope (LAT) began nearly 20 years ago when it was just a concept. Pat was a central member in the operation of the LAT collaboration and he is greatly missed.

  6. Large-area mapping of biodiversity

    USGS Publications Warehouse

    Scott, J.M.; Jennings, M.D.

    1998-01-01

    The age of discovery, description, and classification of biodiversity is entering a new phase. In responding to the conservation imperative, we can now supplement the essential work of systematics with spatially explicit information on species and assemblages of species. This is possible because of recent conceptual, technical, and organizational progress in generating synoptic views of the earth's surface and a great deal of its biological content, at multiple scales of thematic as well as geographic resolution. The development of extensive spatial data on species distributions and vegetation types provides us with a framework for: (a) assessing what we know and where we know it at meso-scales, and (b) stratifying the biological universe so that higher-resolution surveys can be more efficiently implemented, coveting, for example, geographic adequacy of specimen collections, population abundance, reproductive success, and genetic dynamics. The land areas involved are very large, and the questions, such as resolution, scale, classification, and accuracy, are complex. In this paper, we provide examples from the United States Gap Analysis Program on the advantages and limitations of mapping the occurrence of terrestrial vertebrate species and dominant land-cover types over large areas as joint ventures and in multi-organizational partnerships, and how these cooperative efforts can be designed to implement results from data development and analyses as on-the-ground actions. Clearly, new frameworks for thinking about biogeographic information as well as organizational cooperation are needed if we are to have any hope of documenting the full range of species occurrences and ecological processes in ways meaningful to their management. The Gap Analysis experience provides one model for achieving these new frameworks.

  7. Development of large Area Covering Height Model

    NASA Astrophysics Data System (ADS)

    Jacobsen, K.

    2014-04-01

    Height information is a basic part of topographic mapping. Only in special areas frequent update of height models is required, usually the update cycle is quite lower as for horizontal map information. Some height models are available free of charge in the internet; for commercial height models a fee has to be paid. Mostly digital surface models (DSM) with the height of the visible surface are given and not the bare ground height, as required for standard mapping. Nevertheless by filtering of DSM, digital terrain models (DTM) with the height of the bare ground can be generated with the exception of dense forest areas where no height of the bare ground is available. These height models may be better as the DTM of some survey administrations. In addition several DTM from national survey administrations are classified, so as alternative the commercial or free of charge available information from internet can be used. The widely used SRTM DSM is available also as ACE-2 GDEM corrected by altimeter data for systematic height errors caused by vegetation and orientation errors. But the ACE-2 GDEM did not respect neighbourhood information. With the worldwide covering TanDEM-X height model, distributed starting 2014 by Airbus Defence and Space (former ASTRIUM) as WorldDEM, higher level of details and accuracy is reached as with other large area covering height models. At first the raw-version of WorldDEM will be available, followed by an edited version and finally as WorldDEM-DTM a height model of the bare ground. With 12 m spacing and a relative standard deviation of 1.2 m within an area of 1° x 1° an accuracy and resolution level is reached, satisfying also for larger map scales. For limited areas with the HDEM also a height model with 6 m spacing and a relative vertical accuracy of 0.5 m can be generated on demand. By bathymetric LiDAR and stereo images also the height of the sea floor can be determined if the water has satisfying transparency. Another method of getting

  8. Large area silicon sheet by EFG

    NASA Technical Reports Server (NTRS)

    Kalejs, J. P.

    1982-01-01

    Work carried out on the JPL Flat Plate Solar Array Project, for the purpose of developing a method for silicon ribbon production by Edge-defined Film-fed Growth (EEG) for use as low-cost substrate material in terrestrial solar cell manufacture, is described. A multiple ribbon furnace unit that is designed to operate on a continuous basis for periods of at least one week, with melt replenishment and automatic ribbon width control, and to produce silicon sheet at a rate of one square meter per hour, was constructed. Program milestones set for single ribbon furnace operation to demonstrate basic EEG system capabilities with respect to growth speed, thickness and cell performance were achieved for 10 cm wide ribbon: steady-state growth at 4 cm/min and 200 micron thickness over periods of an hour and longer was made routine, and a small area cell efficiency of 13+% demonstrated. Large area cells of average efficiency of 10 to 11%, with peak values of 11 to 12% were also achieved. The integration of these individual performance levels into multiple ribbon furnace operation was not accomplished.

  9. Large area QNDE inspection for airframe integrity

    NASA Technical Reports Server (NTRS)

    Winfree, William P.; Heyman, Joseph S.

    1991-01-01

    Quantitative Nondestructive Evaluation (QNDE) technology is being developed to provide new options for cost effective inspection of airframes. An R&D effort based on five NDE technologies is addressing questions of structural bonding assessment, corrosion detection, multisite damage detection, and fatigue characterization. The research/applications are being conducted by prioritized focussing and staging of the following technologies: (1) thermal NDE; (2) ultrasonic NDE; (3) coherent optical NDE; (4) magnetic imaging NDE; and (5) radiographic NDE. The focus here is on the most recent applications of thermal NDE technology to large area inspection of lap-joint and stiffener bonds. The approach is based on pulsed radiant heating of the airframe and measurement of the surface temperature of the structure with an infrared imager. Several advantages of the technique are that it is noncontacting, inspects one square meter area in a period of less than 2 minutes and has no difficulty inspecting typical curvatures of the fuselage. Numerical models of heat flow in these geometries are used to determine appropriate techniques for reduction of the infrared images, thereby delineating regions of disbonds. These models are also used to determine the optimum heating and measurement times for maximizing the contrast between bonded and unbonded structures. Good agreement is found between these results and experimental measurements, and a comparison of the two are presented. Also presented are results of measurements on samples with fabricated defects which show the technique is able to clearly indicate regions of disbonds. Measurements on an airframe also clearly image subsurface structure.

  10. LARGE AREA LANDMARKS - DYNAMAP V.12.2

    EPA Science Inventory

    GDT Large Area Landmarks represents common landmark areas within United States including military areas, prisons, educational institutions, amusement centers, government centers, sport centers, golf courses, and cemeteries.

  11. Fermi Large Area Telescope Second Source Catalog

    NASA Technical Reports Server (NTRS)

    Nolan, P. L.; Abdo, A. A.; Ackermann, M.; Ajello, M; Allafort, A.; Antolini, E; Bonnell, J.; Cannon, A.; Celik O.; Corbet, R.; Davis, D. S.; DeCesar, M. E.; Ferrara, E. C.; Gehrels, N.; Harding, A. K.; Hays, E.; Johnson, T. E.; McConville, W.; McEnery, J. E; Perkins, J. S.; Racusin, J. L; Scargle, J. D.; Stephens, T. E.; Thompson, D. J.; Troja, E.

    2012-01-01

    We present the second catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24-month period. The Second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in 5 energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 11eV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely gamma-ray-producing source classes.

  12. FERMI LARGE AREA TELESCOPE SECOND SOURCE CATALOG

    SciTech Connect

    Nolan, P. L.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Abdo, A. A.; Ackermann, M.; Antolini, E.; Bonamente, E.; Atwood, W. B.; Belfiore, A.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Ballet, J.; Bastieri, D.; Bignami, G. F. E-mail: Gino.Tosti@pg.infn.it E-mail: tburnett@u.washington.edu; and others

    2012-04-01

    We present the second catalog of high-energy {gamma}-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24 month period. The second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in five energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 MeV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely {gamma}-ray-producing source classes.

  13. Large area atmospheric-pressure plasma jet

    DOEpatents

    Selwyn, Gary S.; Henins, Ivars; Babayan, Steve E.; Hicks, Robert F.

    2001-01-01

    Large area atmospheric-pressure plasma jet. A plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two planar, parallel electrodes are employed to generate a plasma in the volume therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly spacing the rf-powered electrode. Because of the atmospheric pressure operation, there is a negligible density of ions surviving for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike the situation for low-pressure plasma sources and conventional plasma processing methods.

  14. Large area silicon sheet by EFG

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Progress was made in improving ribbon flatness and reducing stress, and in raising cell performance for 10 cm wide ribbon grown in single cartridge EFG furnaces. Optimization of growth conditions resulted in improved ribbon thickness uniformity at a thickness of 200 micron, grown at 4 cm/minute, and growth at this target speed is routinely achieved over periods of the order of one hour or more. With the improved ribbon flatness, fabrication of large area (50 cm2) cells is now possible, and 10 to 11% efficiencies were demonstrated on ribbon grown at 3.5 to 4 cm/minute. Factors limiting performance of the existing multiple ribbon furnace were identified, and growth system improvements implemented to help raise throughput rates and the time percentage of simultaneous three-ribbon growth. However, it is evident that major redesign of this furnace would be needed to overcome shortfalls in its ability to achieve the Technical Features Demonstration goals of 1980. It was decided to start construction of a new multiple ribbon furnace and to incorporate the desired improvements into its design. The construction of this furnace is completed.

  15. Large-area lanthanum hexaboride electron emitter

    SciTech Connect

    Goebel, D.M.; Hirooka, Y.; Sketchley, T.A.

    1985-09-01

    A large-area cathode assembly which is capable of continuous, high-current electron emission is described. The cathode utilizes an indirectly heated lanthanum hexaboride (LaB/sub 6/) disk as the thermionic electron emitter. The LaB/sub 6/ cathode emits over 600 A of electrons at an average of 20 A/cm/sup 2/ continuously with no observable lifetime limits to date after about 400 h of operation in a plasma discharge. Proper clasping of the LaB/sub 6/ disk is required to avoid impurity production from chemical reactions with the holder and to provide adequate support if the disk fractures during rapid thermal cycling. Modification of the LaB/sub 6/ surface composition due to preferential sputtering of boron by hydrogen and argon ions in the plasma discharge has been observed. The surface appearance is consistent with the formation of LaB/sub 4/ as a result of boron depletion. The electron emission capability of the cathode is not significantly altered by the surface change. This surface modification by preferential sputtering is not observed in hollow cathodes where the ion energy from the cathode sheath voltage is typically less than 50 V. The electron emission by the cathode has not been affected by exposure to both air and water during operation. Utilizing thick disks of this intermediate temperature cathode material results in reliable, high-current, long-lifetime electron emitter assemblies.

  16. Airbrushed Nickel Nanoparticles for Large-Area

    SciTech Connect

    Sarac, Mehmet; ANDERSON, BRYAN; Pearce, Ryan; Railsback, Justin; Oni, Adedapo; White, Ryan M.; Hensley, Dale K; Lebeau, James M; Melechko, Anatoli; Tracy, Joseph B

    2013-01-01

    Vertically aligned carbon nanofibers (VACNFs) were grown by plasma-enhanced chemical vapor deposition (PECVD) using Ni nanoparticle (NP) catalysts that were deposited by airbrushing onto Si, Al, Cu, and Ti substrates. Airbrushing is a simple method for depositing catalyst NPs over large areas that is compatible with roll-to-roll processing. The distribution and morphology of VACNFs are affected by the airbrushing parameters and the composition of the metal foil. Highly concentrated Ni NPs in heptane give more uniform distributions than pentane and hexanes, resulting in more uniform coverage of VACNFs. For VACNF growth on metal foils, Si micropowder was added as a precursor for Si-enriched coatings formed in situ on the VACNFs that impart mechanical rigidity. Interactions between the catalyst NPs and the metal substrates impart control over the VACNF morphology. Growth of carbon nanostructures on Cu is particularly noteworthy because the miscibility of Ni with Cu poses challenges for VACNF growth, and carbon nanostructures anchored to Cu substrates are desired as anode materials for Li-ion batteries and for thermal interface materials.

  17. Knowing good from bad: differential activation of human cortical areas by positive and negative outcomes.

    PubMed

    Nieuwenhuis, Sander; Slagter, Heleen A; von Geusau, Niels J Alting; Heslenfeld, Dirk J; Holroyd, Clay B

    2005-06-01

    Previous research has identified a component of the event-related brain potential (ERP), the feedback-related negativity, that is elicited by feedback stimuli associated with unfavourable outcomes. In the present research we used event-related functional magnetic resonance imaging (fMRI) and electroencephalographic (EEG) recordings to test the common hypothesis that this component is generated in the caudal anterior cingulate cortex. The EEG results indicated that our paradigm, a time estimation task with trial-to-trial performance feedback, elicited a large feedback-related negativity (FRN). Nevertheless, the fMRI results did not reveal any area in the caudal anterior cingulate cortex that was differentially activated by positive and negative performance feedback, casting doubt on the notion that the FRN is generated in this brain region. In contrast, we found a number of brain areas outside the posterior medial frontal cortex that were activated more strongly by positive feedback than by negative feedback. These included areas in the rostral anterior cingulate cortex, posterior cingulate cortex, right superior frontal gyrus, and striatum. An anatomically constrained source model assuming equivalent dipole generators in the rostral anterior cingulate, posterior cingulate, and right superior frontal gyrus produced a simulated scalp distribution that corresponded closely to the observed scalp distribution of the FRN. These results support a new hypothesis regarding the neural generators of the FRN, and have important implications for the use of this component as an electrophysiological index of performance monitoring and reward processing. PMID:15978024

  18. Large Area X-ray Spectroscopy Mission

    NASA Technical Reports Server (NTRS)

    Tananbaum, Harvey

    1996-01-01

    The Large Area X-ray Spectroscopy (LAXS) mission study concept has evolved strongly over the last year culminating in the merging of LAXS with the Goddard Space Flight Center (GSFC) proposal for a similar mission, the Next Generation X-ray Observatory (NGXO, PI: Nick White). The resulting merger, re-named the High Throughput X-rays Spectroscopy (HTXS) Mission has also expanded by the inclusion of another SAO proposed new mission concept proposal, the Hard X-Ray Telescope (PI: Paul Gorenstein). The resultant multi-instrument mission retains much of heritage from the LAXS proposal, including the use of multiple satellites for robustness. These mergers resulted from a series of contacts between various team members, via e-mail, telecons, and in-person meetings. The impetus for the mergers was the fundamental similarity between the missions, and the recognition that all three proposal teams had significant contributions to make in the effort to define the next stage in the X-ray exploration of the universe. We have enclosed four items that represent some of the work that has occurred during the first year of the study: first, a presentation at the Leicester meeting, second a presentation that was made to Dan Goldin following the merging of LAXS and NGXO, third a copy of the first announcement for the Workshop, and finally the interim report that was prepared by the HTXS study team towards the end of the first year. This last document provides the foundation for the HTXS Technology Roadmap that is being generated. The HTXS roadmap will define the near-term goals that the merged mission must achieve over the next few years. A web site has been developed and populated that contains much of the material that has been generated over the past year.

  19. Fermi Large Area Telescope Third Source Catalog

    NASA Astrophysics Data System (ADS)

    Acero, F.; Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Belfiore, A.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bogart, J. R.; Bonino, R.; Bottacini, E.; Bregeon, J.; Britto, R. J.; Bruel, P.; Buehler, R.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caputo, R.; Caragiulo, M.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cominsky, L. R.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; DeKlotz, M.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Venere, L.; Drell, P. S.; Dubois, R.; Dumora, D.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Finke, J.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.; Harding, A. K.; Hays, E.; Hewitt, J. W.; Hill, A. B.; Horan, D.; Iafrate, G.; Jogler, T.; Jóhannesson, G.; Johnson, R. P.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Kataoka, J.; Katsuta, J.; Kuss, M.; La Mura, G.; Landriu, D.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Massaro, F.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mirabal, N.; Mizuno, T.; Moiseev, A. A.; Mongelli, M.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nuss, E.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Racusin, J. L.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Rochester, L. S.; Romani, R. W.; Salvetti, D.; Sánchez-Conde, M.; Saz Parkinson, P. M.; Schulz, A.; Siskind, E. J.; Smith, D. A.; Spada, F.; Spandre, G.; Spinelli, P.; Stephens, T. E.; Strong, A. W.; Suson, D. J.; Takahashi, H.; Takahashi, T.; Tanaka, Y.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Torres, D. F.; Torresi, E.; Tosti, G.; Troja, E.; Van Klaveren, B.; Vianello, G.; Winer, B. L.; Wood, K. S.; Wood, M.; Zimmer, S.; Fermi-LAT Collaboration

    2015-06-01

    We present the third Fermi Large Area Telescope (LAT) source catalog (3FGL) of sources in the 100 MeV-300 GeV range. Based on the first 4 yr of science data from the Fermi Gamma-ray Space Telescope mission, it is the deepest yet in this energy range. Relative to the Second Fermi LAT catalog, the 3FGL catalog incorporates twice as much data, as well as a number of analysis improvements, including improved calibrations at the event reconstruction level, an updated model for Galactic diffuse γ-ray emission, a refined procedure for source detection, and improved methods for associating LAT sources with potential counterparts at other wavelengths. The 3FGL catalog includes 3033 sources above 4σ significance, with source location regions, spectral properties, and monthly light curves for each. Of these, 78 are flagged as potentially being due to imperfections in the model for Galactic diffuse emission. Twenty-five sources are modeled explicitly as spatially extended, and overall 238 sources are considered as identified based on angular extent or correlated variability (periodic or otherwise) observed at other wavelengths. For 1010 sources we have not found plausible counterparts at other wavelengths. More than 1100 of the identified or associated sources are active galaxies of the blazar class; several other classes of non-blazar active galaxies are also represented in the 3FGL. Pulsars represent the largest Galactic source class. From source counts of Galactic sources we estimate that the contribution of unresolved sources to the Galactic diffuse emission is ˜3% at 1 GeV.

  20. Polyurethane Masks Large Areas in Electroplating

    NASA Technical Reports Server (NTRS)

    Beasley, J. L.

    1985-01-01

    Polyurethane foam provides effective mask in electroplating of copper or nickel. Thin layer of Turco maskant painted on area to be masked: Layer ensures polyurethane foam removed easily after served its purpose. Component A, isocyanate, and component B, polyol, mixed together and brushed or sprayed on mask area. Mixture reacts, yielding polyurethane foam. Foam prevents deposition of nickel or copper on covered area. New method saves time, increases productivity and uses less material than older procedures.

  1. ISABELLE. Volume 3. Experimental areas, large detectors

    SciTech Connect

    Not Available

    1981-01-01

    This section presents the papers which resulted from work in the Experimental Areas portion of the Workshop. The immediate task of the group was to address three topics. The topics were dictated by the present state of ISABELLE experimental areas construction, the possibility of a phased ISABELLE and trends in physics and detectors.

  2. Gamma-Ray Large Area Space Telescope- GLAST Mission Overview

    NASA Technical Reports Server (NTRS)

    Moiseev, Alexander A.

    2007-01-01

    This viewgraph presentation reviews the Gamma-ray Large Area Space Telescope (GLAST), and the instrumentation that will be on the spacecraft: Large Area Telescope (LAT) and GLAST Burst Monitor (GBM). The presentation revierws in detail the LAT instrument.

  3. Entanglement negativity in a two dimensional harmonic lattice: area law and corner contributions

    NASA Astrophysics Data System (ADS)

    De Nobili, Cristiano; Coser, Andrea; Tonni, Erik

    2016-08-01

    We study the logarithmic negativity and the moments of the partial transpose in the ground state of a two dimensional massless harmonic square lattice with nearest neighbour interactions for various configurations of adjacent domains. At leading order for large domains, the logarithmic negativity and the logarithm of the ratio between the generic moment of the partial transpose and the moment of the reduced density matrix at the same order satisfy an area law in terms of the length of the curve shared by the adjacent regions. We give numerical evidence that the coefficient of the area law term in these quantities is related to the coefficient of the area law term in the Rényi entropies. Whenever the curve shared by the adjacent domains contains vertices, a subleading logarithmic term occurs in these quantities and the numerical values of the corner function for some pairs of angles are obtained. In the special case of vertices corresponding to explementary angles, we provide numerical evidence that the corner function of the logarithmic negativity is given by the corner function of the Rényi entropy of order 1/2.

  4. Large-area mercuric iodide photodectors

    NASA Astrophysics Data System (ADS)

    Markakis, J.; Ortale, C.; Schnepple, W.; Iwanczyk, J.; Dabrowski, A.

    1983-07-01

    The limits of the active area of mercuric iodide photodetectors imposed by the size of available crystals, electronic noise, and the uniformity of charge carrier collection are discussed. Theoretical calculations of the photodetector electronic noise are compared with the experimental results. Different entrance contacts were studied including semitransparent palladium films and conductive liquids. HgI2 photodetectors with active area up to 4 sq cm are matched with NaI(Tl) and CsI(Tl) scintillation crystals and are evaluated as gamma radiation spectrometers.

  5. Large area epitaxial germanane for electronic devices

    NASA Astrophysics Data System (ADS)

    Amamou, Walid; Odenthal, Patrick M.; Bushong, Elizabeth J.; O'Hara, Dante J.; Luo, Yunqiu Kelly; van Baren, Jeremiah; Pinchuk, Igor; Wu, Yi; Ahmed, Adam S.; Katoch, Jyoti; Bockrath, Marc W.; Tom, Harry W. K.; Goldberger, Joshua E.; Kawakami, Roland K.

    2015-09-01

    We report the synthesis and transfer of epitaxial germanane (GeH) onto arbitrary substrates by electrochemical delamination and investigate its optoelectronic properties. GeH films with thickness ranging from 1 to 600 nm (2-1000 layers) and areas up to ˜1 cm2 have been reliably transferred and characterized by photoluminescence, x-ray diffraction, and energy-dispersive x-ray spectroscopy. Wavelength dependent photoconductivity measurements on few-layer GeH exhibit an absorption edge and provide a sensitive characterization tool for ultrathin germanane materials. The transfer process also enables the possibility of integrating germanane into vertically stacked heterostructures.

  6. Large-scale negative polarity magnetic fields on the sun and particle-emitting flares

    NASA Technical Reports Server (NTRS)

    Bumba, V.

    1972-01-01

    Some observational facts about the large-scale patterns formed by solar negative polarity magnetic fields during the 19th and 20th cycles of solar activity are presented. The close relation of the position of occurrence of very large flares accompanied by cosmic ray and PCA events as well as other phenomena of solar activity during the declining part of the 19th cycle of the regularities in the internal structure of large scale negative polarity features are demonstrated.

  7. Large Area Silicon Sheet by EFG

    NASA Technical Reports Server (NTRS)

    Wald, F. V.

    1979-01-01

    Progress made in the development of EFG ribbon growth is discussed. Specific areas covered include: (1) demonstration of multiple growth for ribbons 5 cm wide in runs of 12 and 20 hours duration; (2) a single cartridge crystal growth station was built expanding observational capacity by virtue of an anamorphic optical-video system which allows close observation of the meniscus over 7.5 cm wide, as well as video taping of the ribbon growth process; (3) growth station no.1 achieved reproducible and reliable growth of 7.5 cm wide ribbon at speeds up to 4 cm/min; (4) introduction of the 'mini cold shoe'; (5) increases in cell efficiency due to interface shaping using the 'displaced die' concept; and (6) clarification of the role of gaseous impurities in cartridge furnaces and stabilization of their destabilizing influence on growth.

  8. Large-area silicon sheet task

    NASA Technical Reports Server (NTRS)

    Morrison, A. D.

    1982-01-01

    A set of computer models was used to define a growth system configuration that was then built and used to grow web with lower thermally generated stress. Aspects of research in the edge-defined film-fed growth (EFG) method of making Si ribbon are reported. A technique was developed to determine base resistivity and carrier lifetime in semicrystalline wafers. Automated growth of 150 kg of 15 cm-dia ingot material per crucible is reviewed. Scanning transmisson electron microscopy (STEM) and microprobe investigations of processed EFG ribbon are reported. The chemical composition of the large precipitates was studied. The structural arrangement and the electrical activity of distentions or close to the central twin plane in processed material were studied. The electrical and structural properties of grain boundaries in silicon are discussed. Temperature-dependence measurements of zero-bias conductance, a photoconductivity technique, and deep-level transient spectroscopy (DLTS) were developed. A grooving and staining technique, secondary ion mass spectroscopy, and EBIC measurements in scanning electron microscopy were used to study enhanced diffusion of phosphorus at grain boundaries in polycrystaline silicon. The fundamental mechanisms of abrasion and wear and the deformation of Si by a diamond in various fluid environments are described. The efficiency of solar cells made from EFG ribbon and Semix Inc. material is reported.

  9. Large-area silicon sheet task

    NASA Astrophysics Data System (ADS)

    Morrison, A. D.

    1982-04-01

    A set of computer models was used to define a growth system configuration that was then built and used to grow web with lower thermally generated stress. Aspects of research in the edge-defined film-fed growth (EFG) method of making Si ribbon are reported. A technique was developed to determine base resistivity and carrier lifetime in semicrystalline wafers. Automated growth of 150 kg of 15 cm-dia ingot material per crucible is reviewed. Scanning transmisson electron microscopy (STEM) and microprobe investigations of processed EFG ribbon are reported. The chemical composition of the large precipitates was studied. The structural arrangement and the electrical activity of distentions or close to the central twin plane in processed material were studied. The electrical and structural properties of grain boundaries in silicon are discussed. Temperature-dependence measurements of zero-bias conductance, a photoconductivity technique, and deep-level transient spectroscopy (DLTS) were developed. A grooving and staining technique, secondary ion mass spectroscopy, and EBIC measurements in scanning electron microscopy were used to study enhanced diffusion of phosphorus at grain boundaries in polycrystaline silicon. The fundamental mechanisms of abrasion and wear and the deformation of Si by a diamond in various fluid environments are described. The efficiency of solar cells made from EFG ribbon and Semix Inc. material is reported.

  10. Priority areas for large mammal conservation in Equatorial Guinea.

    PubMed

    Murai, Mizuki; Ruffler, Heidi; Berlemont, Antoine; Campbell, Genevieve; Esono, Fidel; Agbor, Anthony; Mbomio, Domingo; Ebana, Agustín; Nze, Antonio; Kühl, Hjalmar S

    2013-01-01

    Hunting is one of the main driving forces behind large mammal density distribution in many regions of the world. In tropical Africa, urban demand for bushmeat has been shown to dominate over subsistence hunting and its impact often overrides spatial-ecological species characteristics. To effectively protect remaining mammal populations the main factors that influence their distribution need to be integrated into conservation area prioritisation and management plans. This information has been lacking for Río Muni, Equatorial Guinea, as prior studies have been outdated or have not systematically covered the continental region of the country. In this study we evaluated: 1) the relative importance of local vs. commercial hunting; 2) wildlife density of protected vs. non-protected areas; and 3) the importance of ecological factors vs. human influence in driving mammal density distribution in Río Muni. We adopted a systematic countrywide line transect approach with particular focus on apes and elephants, but also including other mammal species. For analysis of field data we used generalised linear models with a set of predictor variables representing ecological conditions, anthropogenic pressure and protected areas. We estimate that there are currently 884 (437-1,789) elephants and 11,097 (8,719-13,592) chimpanzees and gorillas remaining in Río Muni. The results indicate strong hunting pressures on both local and commercial levels, with roads demonstrating a negative impact on elephants and overall mammal body mass. Protected areas played no role in determining any of the mammal species distributions and significant human hunting signs were found inside these protected areas, illustrating the lack of environmental law enforcement throughout the country. Río Muni is currently under-represented in conservation efforts in Western Equatorial Africa, and we recommend a focus on cross-boundary conservation, in particular in the Monte Alén-Monts de Cristal and Río Campo

  11. Priority Areas for Large Mammal Conservation in Equatorial Guinea

    PubMed Central

    Murai, Mizuki; Ruffler, Heidi; Berlemont, Antoine; Campbell, Genevieve; Esono, Fidel; Agbor, Anthony; Mbomio, Domingo; Ebana, Agustín; Nze, Antonio; Kühl, Hjalmar S.

    2013-01-01

    Hunting is one of the main driving forces behind large mammal density distribution in many regions of the world. In tropical Africa, urban demand for bushmeat has been shown to dominate over subsistence hunting and its impact often overrides spatial-ecological species characteristics. To effectively protect remaining mammal populations the main factors that influence their distribution need to be integrated into conservation area prioritisation and management plans. This information has been lacking for Río Muni, Equatorial Guinea, as prior studies have been outdated or have not systematically covered the continental region of the country. In this study we evaluated: 1) the relative importance of local vs. commercial hunting; 2) wildlife density of protected vs. non-protected areas; and 3) the importance of ecological factors vs. human influence in driving mammal density distribution in Río Muni. We adopted a systematic countrywide line transect approach with particular focus on apes and elephants, but also including other mammal species. For analysis of field data we used generalised linear models with a set of predictor variables representing ecological conditions, anthropogenic pressure and protected areas. We estimate that there are currently 884 (437–1,789) elephants and 11,097 (8,719–13,592) chimpanzees and gorillas remaining in Río Muni. The results indicate strong hunting pressures on both local and commercial levels, with roads demonstrating a negative impact on elephants and overall mammal body mass. Protected areas played no role in determining any of the mammal species distributions and significant human hunting signs were found inside these protected areas, illustrating the lack of environmental law enforcement throughout the country. Río Muni is currently under-represented in conservation efforts in Western Equatorial Africa, and we recommend a focus on cross-boundary conservation, in particular in the Monte Alén-Monts de Cristal and R

  12. Auxetic materials with large negative Poisson's ratios based on highly oriented carbon nanotube structures

    NASA Astrophysics Data System (ADS)

    Chen, Luzhuo; Liu, Changhong; Wang, Jiaping; Zhang, Wei; Hu, Chunhua; Fan, Shoushan

    2009-06-01

    Auxetic materials with large negative Poisson's ratios are fabricated by highly oriented carbon nanotube structures. The Poisson's ratio can be obtained down to -0.50. Furthermore, negative Poisson's ratios can be maintained in the carbon nanotube/polymer composites when the nanotubes are embedded, while the composites show much better mechanical properties including larger strain-to-failure (˜22%) compared to the pristine nanotube thin film (˜3%). A theoretical model is developed to predict the Poisson's ratios. It indicates that the large negative Poisson's ratios are caused by the realignment of curved nanotubes during stretching and the theoretical predictions agree well with the experimental results.

  13. CD20-negative diffuse large B-cell lymphomas: biology and emerging therapeutic options.

    PubMed

    Castillo, Jorge J; Chavez, Julio C; Hernandez-Ilizaliturri, Francisco J; Montes-Moreno, Santiago

    2015-06-01

    CD20-negative diffuse large B-cell lymphoma (DLBCL) is a rare and heterogeneous group of lymphoproliferative disorders. Known variants of CD20-negative DLBCL include plasmablastic lymphoma, primary effusion lymphoma, large B-cell lymphoma arising in human herpesvirus 8-associated multicentric Castleman disease and anaplastic lymphoma kinase-positive DLBCL. Given the lack of CD20 expression, atypical cellular morphology and aggressive clinical behavior characterized by chemotherapy resistance and inferior survival rates, CD20-negative DLBCL represents a challenge from the diagnostic and therapeutic perspectives. The goals of the present review are to summarize the current knowledge on the biology of the distinct variants of CD20-negative DLBCL, provide future therapeutic directions based on the limited preclinical and clinical data available, and increase awareness concerning these rare malignancies among pathologists and clinicians. PMID:25641215

  14. INTERIOR VIEW, PREPARING LARGE MOLD IN BOX FLOOR AREA. WORKERS ...

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

    INTERIOR VIEW, PREPARING LARGE MOLD IN BOX FLOOR AREA. WORKERS JUST FILLED THE FLASK WITH SAND FROM A HIGH VELOCITY MECHANICAL SAND THRUSTER. - Stockham Pipe & Fittings Company, Ductile Iron Foundry, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  15. Satellite image collection modeling for large area hazard emergency response

    NASA Astrophysics Data System (ADS)

    Liu, Shufan; Hodgson, Michael E.

    2016-08-01

    Timely collection of critical hazard information is the key to intelligent and effective hazard emergency response decisions. Satellite remote sensing imagery provides an effective way to collect critical information. Natural hazards, however, often have large impact areas - larger than a single satellite scene. Additionally, the hazard impact area may be discontinuous, particularly in flooding or tornado hazard events. In this paper, a spatial optimization model is proposed to solve the large area satellite image acquisition planning problem in the context of hazard emergency response. In the model, a large hazard impact area is represented as multiple polygons and image collection priorities for different portion of impact area are addressed. The optimization problem is solved with an exact algorithm. Application results demonstrate that the proposed method can address the satellite image acquisition planning problem. A spatial decision support system supporting the optimization model was developed. Several examples of image acquisition problems are used to demonstrate the complexity of the problem and derive optimized solutions.

  16. Laser processing system development of large area and high precision

    NASA Astrophysics Data System (ADS)

    Park, Hyeongchan; Ryu, Kwanghyun; Hwang, Taesang

    2013-03-01

    As industry of PCB (Printed Circuit Board) and display growing, this industry requires an increasingly high-precision quality so current cutting process in industry is preferred laser machining than mechanical machining. Now, laser machining is used almost "step and repeat" method in large area, but this method has a problem such as cutting quality in the continuity of edge parts, cutting speed and low productivity. To solve these problems in large area, on-the-fly (stagescanner synchronized system) is gradually increasing. On-the-fly technology is able to process large area with high speed because of stage-scanner synchronized moving. We designed laser-based high precision system with on-the-fly. In this system, we used UV nano-second pulse laser, power controller and scanner with telecentric f-theta lens. The power controller is consisted of HWP(Half Wave Plate), thin film plate polarizer, photo diode, micro step motor and control board. Laser power is possible to monitor real-time and adjust precision power by using power controller. Using this machine, we tested cutting of large area coverlay and sheet type large area PCB by applying on-the-fly. As a result, our developed machine is possible to process large area without the problem of the continuity of edge parts and by high cutting speed than competitor about coverlay.

  17. Negative running of the spectral index, hemispherical asymmetry and the consistency of Planck with large r

    SciTech Connect

    McDonald, John

    2014-11-01

    Planck favours a negative running of the spectral index, with the likelihood being dominated by low multipoles l ∼< 50 and no preference for running at higher l. A negative spectral index is also necessary for the 2- Planck upper bound on the tensor-to-scalar ratio r to be consistent with values significantly larger than 0.1. Planck has also observed a hemispherical asymmetry of the CMB power spectrum, again mostly at low multipoles. Here we consider whether the physics responsible for the hemispherical asymmetry could also account for the negative running of the spectral index and the consistency of Planck with a large value of r. A negative running of the spectral index can be generated if the hemispherical asymmetry is due to a scale- and space-dependent modulation which suppresses the CMB power spectrum at low multipoles. We show that the observed hemispherical asymmetry at low l can be generated while satisfying constraints on the asymmetry at higher l and generating a negative spectral index of the right magnitude to account for the Planck observation and to allow Planck to be consistent with a large value of r.

  18. Fabrication of Large Area Periodic Nanostructures Using Nanosphere Photolithography

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Dey, Dibyendu; Memis, Omer G.; Katsnelson, Alex; Mohseni, Hooman

    2008-10-01

    Large area periodic nanostructures exhibit unique optical and electronic properties and have found many applications, such as photonic band-gap materials, high dense data storage, and photonic devices. We have developed a maskless photolithography method—Nanosphere Photolithography (NSP)—to produce a large area of uniform nanopatterns in the photoresist utilizing the silica micro-spheres to focus UV light. Here, we will extend the idea to fabricate metallic nanostructures using the NSP method. We produced large areas of periodic uniform nanohole array perforated in different metallic films, such as gold and aluminum. The diameters of these nanoholes are much smaller than the wavelength of UV light used and they are very uniformly distributed. The method introduced here inherently has both the advantages of photolithography and self-assembled methods. Besides, it also generates very uniform repetitive nanopatterns because the focused beam waist is almost unchanged with different sphere sizes.

  19. Plasma and Ion Sources in Large Area Coatings: A Review

    SciTech Connect

    Anders, Andre

    2005-02-28

    Efficient deposition of high-quality coatings often requires controlled application of excited or ionized particles. These particles are either condensing (film-forming) or assisting by providing energy and momentum to the film growth process, resulting in densification, sputtering/etching, modification of stress, roughness, texture, etc. In this review, the technical means are surveyed enabling large area application of ions and plasmas, with ion energies ranging from a few eV to a few keV. Both semiconductortype large area (single wafer or batch processing with {approx} 1000 cm{sup 2}) and in-line web and glass-coating-type large area (> 10{sup 7} m{sup 2} annually) are considered. Characteristics and differences between plasma and ion sources are explained. The latter include gridded and gridless sources. Many examples are given, including sources based on DC, RF, and microwave discharges, some with special geometries like hollow cathodes and E x B configurations.

  20. Progress on large-area polarization grating fabrication

    NASA Astrophysics Data System (ADS)

    Miskiewicz, Matthew N.; Kim, Jihwan; Li, Yanming; Komanduri, Ravi K.; Escuti, Michael J.

    2012-06-01

    Over the last several years, we have pioneered liquid crystal polarization gratings (PGs), in both switchable and polymer versions. We have also introduced their use in many applications, including mechanical/non-mechanical laser beam steering and polarization imaging/sensing. Until now, conventional holographic congurations were used to create PGs where the diameter of the active area was limited to 1-2 inches. In this paper, we discuss a new holography setup to fabricate large area PGs using spherical waves as the diverging coherent beams. Various design parameters of this setup are examined for impact on the quality of the recorded PG profile. Using this setup, we demonstrate a large area polymer PG with approximately 66 inch square area, and present detailed characterization.

  1. LAMBDA — Large Area Medipix3-Based Detector Array

    NASA Astrophysics Data System (ADS)

    Pennicard, D.; Lange, S.; Smoljanin, S.; Hirsemann, H.; Graafsma, H.

    2012-11-01

    Medipix3 is a photon-counting readout chip for X-ray detection. It has a small pixel size (55 μm) and a high frame rate with zero dead time, which makes it attractive for experiments at synchrotrons. Using Medipix3, DESY are developing the LAMBDA (Large Area Medipix3-Based Detector Array) system. A single LAMBDA module carries either a single large silicon sensor of 1536 by 512 pixels, or two smaller high-Z sensors. The sensor is bonded to 12 Medipix3 chips, and mounted on a ceramic carrier board. The readout system for the module then provides a fast FPGA, a large RAM and four 10 Gigabit Ethernet links to allow operation at high frame rates. Multiple modules may then be tiled together a larger area. Currently, the first large silicon modules have been constructed and tested at low speed, and the firmware for fast readout is being developed.

  2. Developmental experiments on large-area silicon solar cells

    NASA Astrophysics Data System (ADS)

    Silard, Andrei P.; Nani, Gabriel

    1989-05-01

    Practical ways of attenuating the severe limitations imposed by areal inhomogeneities on the performance of large-area solar cells fabricated on both p- and n-silicon wafers are described, and the results of tests are presented. The p(+)-n-n(+) and n(+)-p-p(+) cells were processed as bifacial devices and tested under both frontside and backside AM1 illumination. It is shown that the combination of a simple design and some of the technological approaches evaluated in this study result in low-cost high-efficiency large-area bifacial silicon solar cells that exhibit with good electrooptical performance.

  3. Large-area metallic photonic lattices for military applications.

    SciTech Connect

    Luk, Ting Shan

    2007-11-01

    In this project we developed photonic crystal modeling capability and fabrication technology that is scaleable to large area. An intelligent optimization code was developed to find the optimal structure for the desired spectral response. In terms of fabrication, an exhaustive survey of fabrication techniques that would meet the large area requirement was reduced to Deep X-ray Lithography (DXRL) and nano-imprint. Using DXRL, we fabricated a gold logpile photonic crystal in the <100> plane. For the nano-imprint technique, we fabricated a cubic array of gold squares. These two examples also represent two classes of metallic photonic crystal topologies, the connected network and cermet arrangement.

  4. Large area high-speed metrology SPM system

    NASA Astrophysics Data System (ADS)

    Klapetek, P.; Valtr, M.; Picco, L.; Payton, O. D.; Martinek, J.; Yacoot, A.; Miles, M.

    2015-02-01

    We present a large area high-speed measuring system capable of rapidly generating nanometre resolution scanning probe microscopy data over mm2 regions. The system combines a slow moving but accurate large area XYZ scanner with a very fast but less accurate small area XY scanner. This arrangement enables very large areas to be scanned by stitching together the small, rapidly acquired, images from the fast XY scanner while simultaneously moving the slow XYZ scanner across the region of interest. In order to successfully merge the image sequences together two software approaches for calibrating the data from the fast scanner are described. The first utilizes the low uncertainty interferometric sensors of the XYZ scanner while the second implements a genetic algorithm with multiple parameter fitting during the data merging step of the image stitching process. The basic uncertainty components related to these high-speed measurements are also discussed. Both techniques are shown to successfully enable high-resolution, large area images to be generated at least an order of magnitude faster than with a conventional atomic force microscope.

  5. Semiconductor-based, large-area, flexible, electronic devices

    DOEpatents

    Goyal, Amit

    2011-03-15

    Novel articles and methods to fabricate the same resulting in flexible, large-area, triaxially textured, single-crystal or single-crystal-like, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  6. Large-area cryocooling for far-infrared telescopes

    NASA Astrophysics Data System (ADS)

    Hoang, Triem T.; O'Connell, Tamara A.; Ku, Jentung; Butler, C. D.; Swanson, Theodore D.

    2003-10-01

    Requirements for cryocooling of large-area heat sources begin to appear in studies of future space missions. Examples are the cooling of (i) the entire structure/mirror of large Far Infrared space telescopes to 4-40K and (ii) cryogenic thermal bus to maintain High Temperature Superconductor electronics to below 75K. The cryocooling system must provide robust/reliable operation and not cause significant vibration to the optical components. But perhaps the most challenging aspect of the system design is the removal of waste heat over a very large area. A cryogenic Loop Heat Pipe (C-LHP)/ cryocooler cooling system was developed with the ultimate goal of meeting the aforementioned requirements. In the proposed cooling concept, the C-LHP collected waste heat from a large-area heat source and then transported it to the cryocooler coldfinger for rejection. A proof-of-concept C-LHP test loop was constructed and performance tested in a vacuum chamber to demonstrate the feasibility of the proposed C-LHP to distribute the cryocooler cooling power over a large area. The test loop was designed to operate with any cryogenic working fluid such as Oxygen/Nitrogen (60-120K), Neon (28-40K), Hydrogen (18-30K), and Helium (2.5-4.5K). Preliminary test results indicated that the test loop had a cooling capacity of 4.2W in the 30-40K temperature range with Neon as the working fluid.

  7. Double hysteresis loops and large negative and positive electrocaloric effects in tetragonal ferroelectrics.

    PubMed

    Wu, Hong-Hui; Zhu, Jiaming; Zhang, Tong-Yi

    2015-10-01

    Phase field modelling and thermodynamic analysis are employed to investigate depolarization and compression induced large negative and positive electrocaloric effects (ECEs) in ferroelectric tetragonal crystalline nanoparticles. The results show that double-hysteresis loops of polarization versus electric field dominate at temperatures below the Curie temperature of the ferroelectric material, when the mechanical compression exceeds a critical value. In addition to the mechanism of pseudo-first-order phase transition (PFOPT), the double-hysteresis loops are also caused by the abrupt rise of macroscopic polarization from the abc phase to the c phase or the sudden fall of macroscopic polarization from the c phase to the abc phase when the temperature increases. This phenomenon is called the electric-field-induced-pseudo-phase transition (EFIPPT) in the present study. Similar to the two types of PFOPTs, the two types of EFIPPTs cause large negative and positive ECEs, respectively, and give the maximum absolute values of negative and positive adiabatic temperature change (ATC ΔT). The temperature associated with the maximum absolute value of negative ATC ΔT is lower than that associated with the maximum positive ATC ΔT. Both maximum absolute values of ATC ΔTs change with the variation in the magnitude of an applied electric field and depend greatly on the compression intensity. PMID:26307461

  8. An ultra large negative dispersion regular octagonal PCF with liquid infiltration

    NASA Astrophysics Data System (ADS)

    Kong, Xiangmin; Li, Xinlu; Jiang, Xingfang; Tang, Bin

    2015-10-01

    For solving the problem of dispersion in fiber communication, this article designed a ultra large negative dispersion regular octagonal PCF with liquid infiltration. The effects of air-hole diameter (d), layer-to-layer spacing (Λ) and refractive index of the infiltrating liquid (nL) on dispersion have been obtained based on Finite Element Method (FEM) by using COMSOL Multiphysics. The results show that with an increase of nL, the dispersion gets blue-shifted and the negative dispersion will increase. However, with the increase of Λ, the dispersion is red-shifted and the negative dispersion will reduce. Again, with the increase of d, the dispersion is red-shifted but with an augment of negative dispersion. This paper's theoretical study shows a high negative dispersion of -13000ps/(nm·km) around 1550nm when d=1.000μm, Λ=1.500μm and nL=1.374. The Dispersion Compensating Fiber (DCF) can effectively compensate the single mode fiber G. 652, which has been widely used. One meter the DCF can compensate 650 meters G. 652.

  9. Toward large-area targets for “TRAKULA”

    NASA Astrophysics Data System (ADS)

    Vascon, A.; Düllmann, Ch. E.; Eberhardt, K.; Kindler, B.; Lommel, B.; Runke, J.

    2011-11-01

    TRAKULA ( Transmutationsrelevante kernphysikalische Untersuchungen langlebiger Aktinide, i.e., nuclear physical investigations of long-lived actinides with relevance to transmutation) is a joint research project of the German Federal Ministry of Science and Education (BMBF) on nuclear physics investigations with modern scientific, technological and numerical methods. Experiments concerning the transmutation of radioactive waste are a central topic of the project. For this, large-area samples (≥40 cm 2) of 235,238U and 239,242Pu compounds are required for the calibration of fission chambers and for fission yield measurements. Another topic within the project requires large-area targets for precise measurements of the half-life, t1/2, of very long-lived α-particle emitters like 144Nd ( t1/2≈2×10 15 y). Here, we report on electrodeposition tests with Gd and Nd (used as chemical homologs of the actinides), which were performed to find optimal deposition conditions for small-area targets that should be applicable to future large-area targets. The layers were produced by molecular plating. A new stirring technique, ultrasonic stirring, was adopted and found to be suitable for producing large-area targets. Moreover, two different current densities (namely 0.7 and 1.4 mA/cm 2) were studied and found appropriate for target preparation. Characterization of the layers with different analytical techniques played a major role in these studies to gain a deeper understanding of the deposition process itself: neutron activation analysis and γ-spectroscopy were used for yield measurements, radiographic imaging for homogeneity studies, scanning electron microscopy for morphology studies, and atomic force microscopy for roughness studies. According to the obtained results, a new electrochemical cell for the production of large-area targets was designed.

  10. Identifying Corridors among Large Protected Areas in the United States

    PubMed Central

    Belote, R. Travis; Dietz, Matthew S.; McRae, Brad H.; Theobald, David M.; McClure, Meredith L.; Irwin, G. Hugh; McKinley, Peter S.; Gage, Josh A.; Aplet, Gregory H.

    2016-01-01

    Conservation scientists emphasize the importance of maintaining a connected network of protected areas to prevent ecosystems and populations from becoming isolated, reduce the risk of extinction, and ultimately sustain biodiversity. Keeping protected areas connected in a network is increasingly recognized as a conservation priority in the current era of rapid climate change. Models that identify suitable linkages between core areas have been used to prioritize potentially important corridors for maintaining functional connectivity. Here, we identify the most “natural” (i.e., least human-modified) corridors between large protected areas in the contiguous Unites States. We aggregated results from multiple connectivity models to develop a composite map of corridors reflecting agreement of models run under different assumptions about how human modification of land may influence connectivity. To identify which land units are most important for sustaining structural connectivity, we used the composite map of corridors to evaluate connectivity priorities in two ways: (1) among land units outside of our pool of large core protected areas and (2) among units administratively protected as Inventoried Roadless (IRAs) or Wilderness Study Areas (WSAs). Corridor values varied substantially among classes of “unprotected” non-core land units, and land units of high connectivity value and priority represent diverse ownerships and existing levels of protections. We provide a ranking of IRAs and WSAs that should be prioritized for additional protection to maintain minimal human modification. Our results provide a coarse-scale assessment of connectivity priorities for maintaining a connected network of protected areas. PMID:27104683

  11. Identifying Corridors among Large Protected Areas in the United States.

    PubMed

    Belote, R Travis; Dietz, Matthew S; McRae, Brad H; Theobald, David M; McClure, Meredith L; Irwin, G Hugh; McKinley, Peter S; Gage, Josh A; Aplet, Gregory H

    2016-01-01

    Conservation scientists emphasize the importance of maintaining a connected network of protected areas to prevent ecosystems and populations from becoming isolated, reduce the risk of extinction, and ultimately sustain biodiversity. Keeping protected areas connected in a network is increasingly recognized as a conservation priority in the current era of rapid climate change. Models that identify suitable linkages between core areas have been used to prioritize potentially important corridors for maintaining functional connectivity. Here, we identify the most "natural" (i.e., least human-modified) corridors between large protected areas in the contiguous Unites States. We aggregated results from multiple connectivity models to develop a composite map of corridors reflecting agreement of models run under different assumptions about how human modification of land may influence connectivity. To identify which land units are most important for sustaining structural connectivity, we used the composite map of corridors to evaluate connectivity priorities in two ways: (1) among land units outside of our pool of large core protected areas and (2) among units administratively protected as Inventoried Roadless (IRAs) or Wilderness Study Areas (WSAs). Corridor values varied substantially among classes of "unprotected" non-core land units, and land units of high connectivity value and priority represent diverse ownerships and existing levels of protections. We provide a ranking of IRAs and WSAs that should be prioritized for additional protection to maintain minimal human modification. Our results provide a coarse-scale assessment of connectivity priorities for maintaining a connected network of protected areas. PMID:27104683

  12. Giant Negative Area Compressibility Tunable in a Soft Porous Framework Material.

    PubMed

    Cai, Weizhao; Gładysiak, Andrzej; Anioła, Michalina; Smith, Vincent J; Barbour, Leonard J; Katrusiak, Andrzej

    2015-07-29

    A soft porous material [Zn(L)2(OH)2]n·Guest (where L is 4-(1H-naphtho[2,3-d]imidazol-1-yl)benzoate, and Guest is water or methanol) exhibits the strongest ever observed negative area compressibility (NAC), an extremely rare property, as at hydrostatic pressure most materials shrink in all directions and few expand in one direction. This is the first NAC reported in metal-organic frameworks (MOFs), and its magnitude, clearly visible and by far the highest of all known materials, can be reversibly tuned by exchanging guests adsorbed from hydrostatic fluids. This counterintuitive strong NAC of [Zn(L)2(OH)2]n·Guest arises from the interplay of flexible [-Zn-O(H)-]n helices with layers of [-Zn-L-]4 quadrangular puckered rings comprising large channel voids. The compression of helices and flattening of puckered rings combine to give a giant piezo-mechanical response, applicable in ultrasensitive sensors and actuators. The extrinsic NAC response to different hydrostatic fluids is due to varied host-guest interactions affecting the mechanical strain within the range permitted by exceptionally high flexibility of the framework. PMID:25945394

  13. Large area, low cost solar cell development and production readiness

    NASA Technical Reports Server (NTRS)

    Michaels, D.

    1982-01-01

    A process sequence for a large area ( or = 25 sq. cm) silicon solar cell was investigated. Generic cell choice was guided by the expected electron fluence, by the packing factors of various cell envelope designs onto each panel to provide needed voltage as well as current, by the weight constraints on the system, and by the cost goals of the contract.

  14. Large-area Overhead Manipulator for Access of Fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Multi-axis, cable-driven manipulators have evolved over many years providing large area suspended platform access, programmability, relatively rigid and flexibly-positioned platform control and full six degree of freedom (DOF) manipulation of sensors and tools. We describe innovations for a new six...

  15. INTERIOR, LARGE OPEN AREA AT THE NORTHERN END OF THE ...

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

    INTERIOR, LARGE OPEN AREA AT THE NORTHERN END OF THE BUILDING, SHOWING CIRCULAR OPENINGS IN DIVIDING WALL, LOOKING NORTH - Eglin Air Force Base, Storehouse & Company Administration, Southeast of Flager Road, Nassau Lane, & southern edge of Weekly Bayou, Valparaiso, Okaloosa County, FL

  16. Ultrahigh conductivity of large area suspended few layer graphene films

    NASA Astrophysics Data System (ADS)

    Rouhi, Nima; Wang, Yung Yu; Burke, Peter J.

    2012-12-01

    Room-temperature (atmospheric-pressure) electrical conductivity measurements of wafer-scale, large-area suspended (few layer) graphene membranes with areas up to 1000 μm2 (30 μm × 30 μm) are presented. Multiple devices on one wafer can be fabricated with high yield from the same chemical vapor deposition grown graphene sheet, transferred from a nickel growth substrate to large opening in a suspended silicon nitride support membrane. This represents areas two to orders of magnitude larger than prior transport studies on any suspended graphene device (single or few layer). We find a sheet conductivity of ˜2500 e2/h (or about 10 Ω/sq) of the suspended graphene, which is an order of magnitude higher than any previously reported sheet conductance of few layer graphene.

  17. Fire-on-fire interactions in three large wilderness areas

    NASA Astrophysics Data System (ADS)

    Teske, Casey C.

    Current knowledge about wildfire occurrence is not complete. Fire researchers and managers hold the assumption that previous wildfires affect subsequent wildfires; however, research regarding the interactions of large wildfires at their common boundaries is missing from the literature. This research focuses on understanding the influence of previous large wildfires on subsequent large wildfires in three wilderness areas: The Greater Bob Marshall, the Selway-Bitterroot, and the Frank Church. Data from the Monitoring Trends in Burn Severity (MTBS) project, which mapped large wildfires in the western United States occurring since 1984, are used for the research. The combination of using wilderness areas and remotely sensed images allows an objective and consistent analysis of fire-on-fire interaction that is extensive in both time and space. Standardized methods for analyzing fire interactions do not currently exist, therefore methods were developed, tested, and refined to describe, quantify, and compare once-burned and re-burned locations within a subset of ten fires in terms of size, location, timing between fires, and severity. These methods were then used to address the question of whether re-burns occur within each of the three wilderness areas. Edge and re-burn characteristics were also derived and quantified. Results were statistically and empirically compared to randomized fire intersections and to published fire history research for each area. Although a low proportion of each study area burns or re-burns, when a new fire encounters a previous fire it re-burns onto the previously burned area approximately 80% of the time. Current large wildfires are behaving in a typical fashion, although on some landscapes the amount of re-burn is not different from what would be expected due to chance. Lastly, the complexity of the post-fire landscape was assessed using texture metrics. Pre-fire and post-fire landscapes were shown to be different, with post-fire landscapes

  18. Large Area Crop Inventory Experiment (LACIE). Phase 1: Evaluation report

    NASA Technical Reports Server (NTRS)

    1976-01-01

    It appears that the Large Area Crop Inventory Experiment over the Great Plains, can with a reasonable expectation, be a satisfactory component of a 90/90 production estimator. The area estimator produced more accurate area estimates for the total winter wheat region than for the mixed spring and winter wheat region of the northern Great Plains. The accuracy does appear to degrade somewhat in regions of marginal agriculture where there are small fields and abundant confusion crops. However, it would appear that these regions tend also to be marginal with respect to wheat production and thus increased area estimation errors do not greatly influence the overall production estimation accuracy in the United States. The loss of segments resulting from cloud cover appears to be a random phenomenon that introduces no significant bias into the estimates. This loss does increase the variance of the estimates.

  19. Spatially explicit shallow landslide susceptibility mapping over large areas

    USGS Publications Warehouse

    Bellugi, Dino; Dietrich, William E.; Stock, Jonathan D.; McKean, Jim; Kazian, Brian; Hargrove, Paul

    2011-01-01

    Recent advances in downscaling climate model precipitation predictions now yield spatially explicit patterns of rainfall that could be used to estimate shallow landslide susceptibility over large areas. In California, the United States Geological Survey is exploring community emergency response to the possible effects of a very large simulated storm event and to do so it has generated downscaled precipitation maps for the storm. To predict the corresponding pattern of shallow landslide susceptibility across the state, we have used the model Shalstab (a coupled steady state runoff and infinite slope stability model) which susceptibility spatially explicit estimates of relative potential instability. Such slope stability models that include the effects of subsurface runoff on potentially destabilizing pore pressure evolution require water routing and hence the definition of upslope drainage area to each potential cell. To calculate drainage area efficiently over a large area we developed a parallel framework to scale-up Shalstab and specifically introduce a new efficient parallel drainage area algorithm which produces seamless results. The single seamless shallow landslide susceptibility map for all of California was accomplished in a short run time, and indicates that much larger areas can be efficiently modelled. As landslide maps generally over predict the extent of instability for any given storm. Local empirical data on the fraction of predicted unstable cells that failed for observed rainfall intensity can be used to specify the likely extent of hazard for a given storm. This suggests that campaigns to collect local precipitation data and detailed shallow landslide location maps after major storms could be used to calibrate models and improve their use in hazard assessment for individual storms.

  20. Fast algorithm for the solution of large-scale non-negativity constrained least squares problems.

    SciTech Connect

    Van Benthem, Mark Hilary; Keenan, Michael Robert

    2004-06-01

    Algorithms for multivariate image analysis and other large-scale applications of multivariate curve resolution (MCR) typically employ constrained alternating least squares (ALS) procedures in their solution. The solution to a least squares problem under general linear equality and inequality constraints can be reduced to the solution of a non-negativity-constrained least squares (NNLS) problem. Thus the efficiency of the solution to any constrained least square problem rests heavily on the underlying NNLS algorithm. We present a new NNLS solution algorithm that is appropriate to large-scale MCR and other ALS applications. Our new algorithm rearranges the calculations in the standard active set NNLS method on the basis of combinatorial reasoning. This rearrangement serves to reduce substantially the computational burden required for NNLS problems having large numbers of observation vectors.

  1. Large area, surface discharge pumped, vacuum ultraviolet light source

    DOEpatents

    Sze, Robert C.; Quigley, Gerard P.

    1996-01-01

    Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source. A contamination-free VUV light source having a 225 cm.sup.2 emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm.sup.2 at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing.

  2. Large area, surface discharge pumped, vacuum ultraviolet light source

    DOEpatents

    Sze, R.C.; Quigley, G.P.

    1996-12-17

    Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source is disclosed. A contamination-free VUV light source having a 225 cm{sup 2} emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm{sup 2} at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing. 3 figs.

  3. Large area, dense silicon nanowire array chemical sensors

    SciTech Connect

    Talin, A. Alec; Hunter, Luke L.; Leonard, Francois; Rokad, Bhavin

    2006-10-09

    The authors present a simple top-down approach based on nanoimprint lithography to create dense arrays of silicon nanowires over large areas. Metallic contacts to the nanowires and a bottom gate allow the operation of the array as a field-effect transistor with very large on/off ratios. When exposed to ammonia gas or cyclohexane solutions containing nitrobenzene or phenol, the threshold voltage of the field-effect transistor is shifted, a signature of charge transfer between the analytes and the nanowires. The threshold voltage shift is proportional to the Hammett parameter and the concentration of the nitrobenzene and phenol analytes.

  4. First results of negative-ion-based NBI test-stand for Large Helical Device

    NASA Astrophysics Data System (ADS)

    Takeiri, Y.; Ando, A.; Kaneko, O.; Oka, Y.; Tsumori, K.; Akiyama, R.; Kawamoto, T.; Kuroda, T.

    1992-10-01

    A negative-ion-based NBI test-stand has been constructed in Toki site of National Institute for Fusion Science (NIFS). This Toki test-stand has facilities to produce 2.5 MW neutral beam power with the energy of 125 keV for hydrogen and 250 keV for deuterium, which is utilized for developing a unit of neutral beam injection (NBI) system for Large Helical Device (LHD). All components of the Toki test-stand are installed on the basis of conceptual design of the LHD-NBI system. Development of a high-current negative ion source with vacuum-immersed structure is one of the main objectives of the test-stand, as well as transport of a high-energy beam with a small divergence angle. It is also an important subject to test all of hardware components such as beam dumps and cryo-pumps. Experiments started in July.

  5. Evolution of magnetically rotating arc into large area arc plasma

    NASA Astrophysics Data System (ADS)

    Wang, Cheng; Li, Wan-Wan; Zhang, Xiao-Ning; Zha, Jun; Xia, Wei-Dong

    2015-06-01

    An arc channel tends to shrink due to its conductivity increasing with the increase of temperature. In this study, to generate large area arc plasma, we construct a magnetically rotating arc plasma generator, which mainly consists of a lanthanide tungsten cathode (13 mm in diameter), a concentric cylindrical graphite anode chamber (60 mm in diameter) and a solenoid coil for producing an axial magnet field. By controlling the cold gas flow, the magnetically rotating arc evolves from constricted mode to diffuse mode, which almost fills the whole arc chamber cross section. Results show that the diffuse arc plasma has better uniformity and stability. The formation mechanism of large area arc plasma is discussed in this paper. Project supported by the National Natural Science Foundation of China (Grant Nos. 11035005, 11475174, and 50876101) and the Science Instrument Foundation of the Chinese Academy of Sciences (Grant No. Y201162).

  6. High Energy Astrophysics with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Hays, Elizabeth

    2009-01-01

    This slide presentation reviews some of the findings of the Large Area Telescope (LAT) aboard the Fermi Observatory. It includes information about the LAT, and the Gamma-Ray Burst Monitor (GBM), detection of the quiet sun and the moon in gamma rays, Pulsars observed by the observatory, Globular Star Clusters, Active Galactic Nucleus, and Gamma-Ray Bursts, with specific information about GRB 080916C.

  7. Characterization of Large Area APDs for the EXO-200 Detector

    SciTech Connect

    Neilson, R.; LePort, F.; Pocar, A.; Kumar, K.; Odian, A.; Prescott, C.Y.; Tenev, V.; Ackerman, N.; Akimov, D.; Auger, M.; Benitez-Medina, C.; Breidenbach, M.; Burenkov, A.; Conley, R.; Cook, S.; deVoe, R.; Dolinski, M.J.; Fairbank, W., Jr.; Farine, J.; Fierlinger, P.; Flatt, B.; /Stanford U., Phys. Dept. /Bern U., LHEP /Stanford U., Phys. Dept. /Maryland U. /Colorado State U. /Laurentian U. /Carleton U. /SLAC /Maryland U. /Moscow, ITEP /Alabama U. /SLAC /Colorado State U. /Stanford U., Phys. Dept. /Alabama U. /Stanford U., Phys. Dept. /Alabama U. /SLAC /Carleton U. /SLAC /Maryland U. /Moscow, ITEP /Carleton U. /Stanford U., Phys. Dept. /Bern U., LHEP /SLAC /Laurentian U. /SLAC /Maryland U.

    2011-12-02

    EXO-200 uses 468 large area avalanche photodiodes (LAAPDs) for detection of scintillation light in an ultra-low-background liquid xenon (LXe) detector. We describe initial measurements of dark noise, gain and response to xenon scintillation light of LAAPDs at temperatures from room temperature to 169 K - the temperature of liquid xenon. We also describe the individual characterization of more than 800 LAAPDs for selective installation in the EXO-200 detector.

  8. Large diurnal temperature fluctuations negatively influence Aedes aegypti (Diptera: Culicidae) life-history traits.

    PubMed

    Carrington, Lauren B; Seifert, Stephanie N; Willits, Neil H; Lambrechts, Louis; Scott, Thomas W

    2013-01-01

    Seasonal variation in dengue virus transmission in northwestern Thailand is inversely related to the magnitude of diurnal temperature fluctuations, although mean temperature does not vary significantly across seasons. We tested the hypothesis that diurnal temperature fluctuations negatively influence epidemiologically important life-history traits of the primary dengue vector, Aedes aegypti (L.), compared with a constant 26 degrees C temperature. A large diurnal temperature range (DTR) (approximately equals 18 degrees C daily swing) extended immature development time (>1 d), lowered larval survival (approximately equals 6%), and reduced adult female reproductive output by 25% 14 d after blood feeding, relative to the constant 26 degreesC temperature. A small DTR (approximately equal 8 degrees C daily swing) led to a negligible or slightly positive effect on the life history traits tested. Our results indicate that there is a negative impact of large DTR on mosquito biology and are consistent with the hypothesis that, in at least some locations, large temperature fluctuations contribute to seasonal reduction in dengue virus transmission. PMID:23427651

  9. Advanced Large Area Plastic Scintillator Project (ALPS): Final Report

    SciTech Connect

    Jordan, David V.; Reeder, Paul L.; Todd, Lindsay C.; Warren, Glen A.; McCormick, Kathleen R.; Stephens, Daniel L.; Geelhood, Bruce D.; Alzheimer, James M.; Crowell, Shannon L.; Sliger, William A.

    2008-02-05

    The advanced Large-Area Plastic Scintillator (ALPS) Project at Pacific Northwest National Laboratory investigated possible technological avenues for substantially advancing the state-of-the-art in gamma-ray detection via large-area plastic scintillators. The three predominant themes of these investigations comprised the following: * Maximizing light collection efficiency from a single large-area sheet of plastic scintillator, and optimizing hardware event trigger definition to retain detection efficiency while exploiting the power of coincidence to suppress single-PMT "dark current" background; * Utilizing anti-Compton vetoing and supplementary spectral information from a co-located secondary, or "Back" detector, to both (1) minimize Compton background in the low-energy portion of the "Front" scintillator's pulse-height spectrum, and (2) sharpen the statistical accuracy of the front detector's low-energy response prediction as impelmented in suitable energy-windowing algorithms; and * Investigating alternative materials to enhance the intrinsic gamma-ray detection efficiency of plastic-based sensors.

  10. Large area nanostructured arrays: optical properties of metallic nanotubes.

    PubMed

    Fröhlich, Katja; Hojati-Talemi, Pejman; Bishop, Matthew; Zuber, Kamil; Murphy, Peter; Evans, Drew

    2013-05-01

    In this study, large area metallic nanotube arrays on flexible plastic substrates are produced by templating the growth of a cosputtered alloy using anodized aluminum oxide membranes. These nanotube arrays are prepared over large areas (ca. squared centimeters) by reducing the residual stress within the thin multilayered structure. The nanotubes are approximately 20 nm in inner diameter, having walls of <10 nm in thickness, and are arranged in a close packed configuration. Optically the nanotube arrays exhibit light trapping behavior (not plasmonic), where the reflectivity is less than 15% across the visible spectra compared to >40% for a flat sample using the same alloy. When the nanotubes are exposed to high relative humidity, they spontaneously fill, with a concomitant change in their visual appearance. The filling of the nanotubes is confirmed using contact angle measurements, with the nanotubes displaying a strong hydrophilic character compared to the weak behavior of the flat sample. The ability to easily fabricate large area nanotube arrays which display exotic behavior paves the way for their uptake in real world applications such as sensors and solar energy devices. PMID:23582083

  11. Large area radiation source for water and wastewater treatment

    NASA Astrophysics Data System (ADS)

    Mueller, Michael T.; Lee, Seungwoo; Kloba, Anthony; Hellmer, Ronald; Kumar, Nalin; Eaton, Mark; Rambo, Charlotte; Pillai, Suresh

    2011-06-01

    There is a strong desire for processes that improve the safety of water supplies and that minimize disinfection byproducts. Stellarray is developing mercury-free next-generation x-ray and UV-C radiation sources in flat-panel and pipe form factors for water and wastewater treatment applications. These new radiation sources are designed to sterilize sludge and effluent, and to enable new treatment approaches to emerging environmental concerns such as the accumulation of estrogenic compounds in water. Our UV-C source, based on cathodoluminescent technology, differs significantly from traditional disinfection approaches using mercury arc lamps or UV LEDs. Our sources accelerate electrons across a vacuum gap, converting their energy into UV-C when striking a phosphor, or x-rays when striking a metallic anode target. Stellarray's large area radiation sources for wastewater treatment allow matching of the radiation source area to the sterilization target area for maximum coverage and improved efficiency.

  12. Characterization and Calibration of Large Area Resistive Strip Micromegas Detectors

    NASA Astrophysics Data System (ADS)

    Lösel, Philipp; ATLAS Muon Collaboration

    2016-07-01

    Resistive strip Micromegas detectors have been tested extensively as small detectors of about 10×10 cm2 in size and they work reliably at high rates of 100 kHz/cm2 and above. Tracking resolution well below 100 μm has been observed for 100 GeV muons and pions. Micromegas detectors are meanwhile proposed as large area muon precision trackers of 2-3 m2 in size. To investigate possible differences between small and large detectors, a 1 m2 detector with 2048 resistive strips at a pitch of 450 μm was studied in the LMU Cosmic Ray Measurement Facility (CRMF) using two 4×2.2 m2 large Monitored Drift Tube (MDT) chambers for cosmic muon reference tracking. A segmentation of the resistive strip anode plane in 57.6 mm×93 mm large areas has been realized by the readout of 128 strips with one APV25 chip each and by eleven 93 mm broad trigger scintillators placed along the readout strips. This allows for mapping of homogeneity in pulse height and efficiency, determination of signal propagation along the 1 m long anode strips and calibration of the position of the anode strips.

  13. Large areas elemental mapping by ion beam analysis techniques

    NASA Astrophysics Data System (ADS)

    Silva, T. F.; Rodrigues, C. L.; Curado, J. F.; Allegro, P.; Moro, M. V.; Campos, P. H. O. V.; Santos, S. B.; Kajiya, E. A. M.; Rizzutto, M. A.; Added, N.; Tabacniks, M. H.

    2015-07-01

    The external beam line of the Laboratory for Material Analysis with Ion Beams (LAMFI) is a versatile setup for multi-technique analysis. X-ray detectors for Particle Induced X-rays Emission (PIXE) measurements, a Gamma-ray detector for Particle Induced Gamma- ray Emission (PIGE), and a particle detector for scattering analysis, such as Rutherford Backscattering Spectrometry (RBS), were already installed. In this work, we present some results, using a large (60-cm range) XYZ computer controlled sample positioning system, completely developed and build in our laboratory. The XYZ stage was installed at the external beam line and its high spacial resolution (better than 5 μm over the full range) enables positioning the sample with high accuracy and high reproducibility. The combination of a sub-millimeter beam with the large range XYZ robotic stage is being used to produce elemental maps of large areas in samples like paintings, ceramics, stones, fossils, and all sort of samples. Due to its particular characteristics, this is a unique device in the sense of multi-technique analysis of large areas. With the continuous development of the external beam line at LAMFI, coupled to the robotic XYZ stage, it is becoming a robust and reliable option for regular analysis of trace elements (Z > 5) competing with the traditional in-vacuum ion-beam-analysis with the advantage of automatic rastering.

  14. SPLASH: A Southern Parkes Large Area Survey in Hydroxyl

    NASA Astrophysics Data System (ADS)

    Dawson, Joanne; Caswell, James; Gomez, Jose F.; Mcclure-Griffiths, Naomi; Lo, Nadia; Jones, Paul; Dickey, John; Cunningham, Maria; Green, James; Carretti, Ettore; Ellingsen, Simon; Walsh, Andrew; Purcell, Cormac; Breen, Shari; Hennebelle, Patrick; Imai, Hiroshi; Lowe, Vicki; Gibson, Steven; Brown, Courtney; Krishnan, Vasaant

    2014-04-01

    The OH 18 cm lines are powerful and versatile probes of diffuse molecular gas, that trace a largely unstudied component of the Galactic ISM. SPLASH (the Southern Parkes Large Area Survey in Hydroxyl) is a large, unbiased and fully-sampled survey of OH emission, absorption and masers in the Galactic Plane that will achieve sensitivities an order of magnitude better than previous work. The survey is answering critical questions on the global distribution of diffuse OH, the degree to which it traces ‘hidden’ material caught between the regimes probed by traditional tracers of the neutral ISM, and its role as a probe of molecular cloud formation. As a blind survey for all four ground-state transitions, SPLASH is also detecting many new OH masers, facilitating a broad range of astrophysical studies. This proposal requests 250 hours to complete Phase 1 of the SPLASH project, which is mapping 152 square degrees in the inner Galactic Plane, including the Galactic Centre.

  15. Improvement of accelerator of negative ion source on the Large Helical Device

    NASA Astrophysics Data System (ADS)

    Kisaki, M.; Ikeda, K.; Osakabe, M.; Tsumori, K.; Nakano, H.; Geng, S.; Nagaoka, K.; Kaneko, O.; Takeiri, Y.

    2016-02-01

    To improve the performance of negative-ion based neutral beam injection on the Large Helical Device, the accelerator was modified on the basis of numerical investigations. A field limiting ring was installed on the upper side of a grounded grid (GG) support and a multi-slot GG was adopted instead of a multi-aperture GG. As a result, the voltage holding capability is improved and the heat load on the GG decreases by 40%. In addition, the arc efficiency is improved significantly only by replacing the GG.

  16. Three-Body Recombination of {sup 6}Li Atoms with Large Negative Scattering Lengths

    SciTech Connect

    Braaten, Eric; Kang, Daekyoung; Platter, Lucas; Hammer, H.-W.

    2009-08-14

    The three-body recombination rate at threshold for distinguishable atoms with large negative pair scattering lengths is calculated in the zero-range approximation. The only parameters in this limit are the 3 scattering lengths and the Efimov parameter, which can be complex-valued. We provide semianalytic expressions for the cases of 2 or 3 equal scattering lengths, and we obtain numerical results for the general case of 3 different scattering lengths. Our general result is applied to the three lowest hyperfine states of {sup 6}Li atoms. Comparisons with recent experiments provide indications of loss features associated with Efimov trimers near the 3-atom threshold.

  17. Improvement of accelerator of negative ion source on the Large Helical Device.

    PubMed

    Kisaki, M; Ikeda, K; Osakabe, M; Tsumori, K; Nakano, H; Geng, S; Nagaoka, K; Kaneko, O; Takeiri, Y

    2016-02-01

    To improve the performance of negative-ion based neutral beam injection on the Large Helical Device, the accelerator was modified on the basis of numerical investigations. A field limiting ring was installed on the upper side of a grounded grid (GG) support and a multi-slot GG was adopted instead of a multi-aperture GG. As a result, the voltage holding capability is improved and the heat load on the GG decreases by 40%. In addition, the arc efficiency is improved significantly only by replacing the GG. PMID:26932049

  18. Synthesis of Large Area Graphene for High Performance in Flexible Optoelectronic Devices

    PubMed Central

    Polat, Emre O.; Balci, Osman; Kakenov, Nurbek; Uzlu, Hasan Burkay; Kocabas, Coskun; Dahiya, Ravinder

    2015-01-01

    This work demonstrates an attractive low-cost route to obtain large area and high-quality graphene films by using the ultra-smooth copper foils which are typically used as the negative electrodes in lithium-ion batteries. We first compared the electronic transport properties of our new graphene film with the one synthesized by using commonly used standard copper foils in chemical vapor deposition (CVD). We observed a stark improvement in the electrical performance of the transistors realized on our graphene films. To study the optical properties on large area, we transferred CVD based graphene to transparent flexible substrates using hot lamination method and performed large area optical scanning. We demonstrate the promise of our high quality graphene films for large areas with ~400 cm2 flexible optical modulators. We obtained a profound light modulation over a broad spectrum by using the fabricated large area transparent graphene supercapacitors and we compared the performance of our devices with the one based on graphene from standard copper. We propose that the copper foils used in the lithium-ion batteries could be used to obtain high-quality graphene at much lower-cost, with the improved performance of electrical transport and optical properties in the devices made from them. PMID:26578425

  19. Synthesis of Large Area Graphene for High Performance in Flexible Optoelectronic Devices.

    PubMed

    Polat, Emre O; Balci, Osman; Kakenov, Nurbek; Uzlu, Hasan Burkay; Kocabas, Coskun; Dahiya, Ravinder

    2015-01-01

    This work demonstrates an attractive low-cost route to obtain large area and high-quality graphene films by using the ultra-smooth copper foils which are typically used as the negative electrodes in lithium-ion batteries. We first compared the electronic transport properties of our new graphene film with the one synthesized by using commonly used standard copper foils in chemical vapor deposition (CVD). We observed a stark improvement in the electrical performance of the transistors realized on our graphene films. To study the optical properties on large area, we transferred CVD based graphene to transparent flexible substrates using hot lamination method and performed large area optical scanning. We demonstrate the promise of our high quality graphene films for large areas with ~400 cm(2) flexible optical modulators. We obtained a profound light modulation over a broad spectrum by using the fabricated large area transparent graphene supercapacitors and we compared the performance of our devices with the one based on graphene from standard copper. We propose that the copper foils used in the lithium-ion batteries could be used to obtain high-quality graphene at much lower-cost, with the improved performance of electrical transport and optical properties in the devices made from them. PMID:26578425

  20. Synthesis of Large Area Graphene for High Performance in Flexible Optoelectronic Devices

    NASA Astrophysics Data System (ADS)

    Polat, Emre O.; Balci, Osman; Kakenov, Nurbek; Uzlu, Hasan Burkay; Kocabas, Coskun; Dahiya, Ravinder

    2015-11-01

    This work demonstrates an attractive low-cost route to obtain large area and high-quality graphene films by using the ultra-smooth copper foils which are typically used as the negative electrodes in lithium-ion batteries. We first compared the electronic transport properties of our new graphene film with the one synthesized by using commonly used standard copper foils in chemical vapor deposition (CVD). We observed a stark improvement in the electrical performance of the transistors realized on our graphene films. To study the optical properties on large area, we transferred CVD based graphene to transparent flexible substrates using hot lamination method and performed large area optical scanning. We demonstrate the promise of our high quality graphene films for large areas with ~400 cm2 flexible optical modulators. We obtained a profound light modulation over a broad spectrum by using the fabricated large area transparent graphene supercapacitors and we compared the performance of our devices with the one based on graphene from standard copper. We propose that the copper foils used in the lithium-ion batteries could be used to obtain high-quality graphene at much lower-cost, with the improved performance of electrical transport and optical properties in the devices made from them.

  1. Negative ion production and beam extraction processes in a large ion source (invited)

    NASA Astrophysics Data System (ADS)

    Tsumori, K.; Ikeda, K.; Nakano, H.; Kisaki, M.; Geng, S.; Wada, M.; Sasaki, K.; Nishiyama, S.; Goto, M.; Serianni, G.; Agostinetti, P.; Sartori, E.; Brombin, M.; Veltri, P.; Wimmer, C.; Nagaoka, K.; Osakabe, M.; Takeiri, Y.; Kaneko, O.

    2016-02-01

    Recent research results on negative-ion-rich plasmas in a large negative ion source have been reviewed. Spatial density and flow distributions of negative hydrogen ions (H-) and positive hydrogen ions together with those of electrons are investigated with a 4-pin probe and a photodetachment (PD) signal of a Langmuir probe. The PD signal is converted to local H- density from signal calibration to a scanning cavity ring down PD measurement. Introduction of Cs changes the slope of plasma potential local distribution depending upon the plasma grid bias. A higher electron density H2 plasma locally shields the bias potential and behaves like a metallic free electron gas. On the other hand, the bias and extraction electric fields penetrate in a Cs-seeded electronegative plasma even when the electron density is similar. Electrons are transported by the penetrated electric fields from the driver region along and across the filter and electron deflection magnetic fields. Plasma ions exhibited a completely different response against the penetration of electric fields.

  2. Negative ion production and beam extraction processes in a large ion source (invited).

    PubMed

    Tsumori, K; Ikeda, K; Nakano, H; Kisaki, M; Geng, S; Wada, M; Sasaki, K; Nishiyama, S; Goto, M; Serianni, G; Agostinetti, P; Sartori, E; Brombin, M; Veltri, P; Wimmer, C; Nagaoka, K; Osakabe, M; Takeiri, Y; Kaneko, O

    2016-02-01

    Recent research results on negative-ion-rich plasmas in a large negative ion source have been reviewed. Spatial density and flow distributions of negative hydrogen ions (H(-)) and positive hydrogen ions together with those of electrons are investigated with a 4-pin probe and a photodetachment (PD) signal of a Langmuir probe. The PD signal is converted to local H(-) density from signal calibration to a scanning cavity ring down PD measurement. Introduction of Cs changes the slope of plasma potential local distribution depending upon the plasma grid bias. A higher electron density H2 plasma locally shields the bias potential and behaves like a metallic free electron gas. On the other hand, the bias and extraction electric fields penetrate in a Cs-seeded electronegative plasma even when the electron density is similar. Electrons are transported by the penetrated electric fields from the driver region along and across the filter and electron deflection magnetic fields. Plasma ions exhibited a completely different response against the penetration of electric fields. PMID:26932108

  3. Effects of electrolyte gating on photoluminescence spectra of large-area WSe2 monolayer films

    NASA Astrophysics Data System (ADS)

    Matsuki, Keiichiro; Pu, Jiang; Kozawa, Daichi; Matsuda, Kazunari; Li, Lain-Jong; Takenobu, Taishi

    2016-06-01

    We fabricated electric double-layer transistors comprising large-area WSe2 monolayers and investigated the effects of electrolyte gating on their photoluminescence (PL) spectra. Using the efficient gating effects of electric double layers, we succeeded in the application of a large electric field (∼107 V cm‑1) and the accumulation of high carrier density (>1013 cm‑2). As a result, we observed PL spectra based on both positively and negatively charged excitons and their gate-voltage-dependent redshifts, suggesting the effects of both an electric field and charge accumulation.

  4. Large nuclear vacuoles in spermatozoa negatively affect pregnancy rate in IVF cycles

    PubMed Central

    Ghazali, Shahin; Talebi, Ali Reza; Khalili, Mohammad Ali; Aflatoonian, Abbas; Esfandiari, Navid

    2015-01-01

    Background: Recently, motile sperm organelle morphology examination (MSOME) criteria as a new real time tool for evaluation of spermatozoa in intracytoplasmic sperm injection (ICSI) cycles has been considered. Objective: The aim was to investigate the predictive value of MSOME in in vitro fertilization (IVF) in comparison to ICSI cycles and evaluation of the association between MSOME parameters and traditional sperm parameters in both groups. Materials and Methods: This is a cross sectional prospective analysis of MSOME parameters in IVF (n=31) and ICSI cycles (n=35). MSOME parameters were also evaluated as the presence of vacuole (none, small, medium, large or mix); head size (normal, small or large); cytoplasmic droplet; head shape and acrosome normality. In sub-analysis, MSOME parameters were compared between two groups with successful or failed clinical pregnancy in each group. Results: In IVF group, the rate of large nuclear vacuole showed significant increase in failed as compared to successful pregnancies (13.81±9.7vs7.38±4.4, respectively, p=0.045) while MSOME parameters were the same between successful and failed pregnancies in ICSI group. Moreover, a negative correlation was noticed between LNV and sperm shape normalcy. In ICSI group, a negative correlation was established between cytoplasmic droplet and sperm shape normalcy. In addition, there was a positive correlation between sperm shape normalcy and non-vacuolated spermatozoa. Conclusion: The high rate of large nuclear vacuoles in sperm used in IVF cycles with failed pregnancies confirms that MSOME, is a helpful tool for fine sperm morphology assessment, and its application may enhance the assisted reproduction technology success rates. PMID:26494990

  5. Application issues for large-area electrochromic windows incommercial buildings

    SciTech Connect

    Lee, Eleanor S.; DiBartolomeo, D.L.

    2000-05-01

    Projections of performance from small-area devices to large-area windows and enterprise marketing have created high expectations for electrochromic glazings. As a result, this paper seeks to precipitate an objective dialog between material scientists and building-application scientists to determine whether actual large-area electrochromic devices will result in significant performance benefits and what material improvements are needed, if any, to make electrochromics more practical for commercial building applications. Few in-situ tests have been conducted with large-area electrochromic windows applied in buildings. This study presents monitored results from a full-scale field test of large-area electrochromic windows to illustrate how this technology will perform in commercial buildings. The visible transmittance (Tv) of the installed electrochromic ranged from 0.11 to 0.38. The data are limited to the winter period for a south-east-facing window. The effect of actual device performance on lighting energy use, direct sun control, discomfort glare, and interior illumination is discussed. No mechanical system loads were monitored. These data demonstrate the use of electrochromics in a moderate climate and focus on the most restrictive visual task: computer use in offices. Through this small demonstration, we were able to determine that electrochromic windows can indeed provide unmitigated transparent views and a level of dynamic illumination control never before seen in architectural glazing materials. Daily lighting energy use was 6-24 percent less compared to the 11 percent-glazing, with improved interior brightness levels. Daily lighting energy use was 3 percent less to 13 percent more compared to the 38 percent-glazing, with improved window brightness control. The electrochromic window may not be able to fulfill both energy-efficiency and visual comfort objectives when low winter direct sun is present, particularly for computer tasks using cathode-ray tube (CRT

  6. Modeling activities on the negative-ion-based Neutral Beam Injectors of the Large Helical Device

    SciTech Connect

    Agostinetti, P.; Antoni, V.; Chitarin, G.; Pilan, N.; Serianni, G.; Veltri, P.; Cavenago, M.; Nakano, H.; Takeiri, Y.; Tsumori, K.

    2011-09-26

    At the National Institute for Fusion Science (NIFS) large-scaled negative ion sources have been widely used for the Neutral Beam Injectors (NBIs) mounted on the Large Helical Device (LHD), which is the world-largest superconducting helical system. These injectors have achieved outstanding performances in terms of beam energy, negative-ion current and optics, and represent a reference for the development of heating and current drive NBIs for ITER.In the framework of the support activities for the ITER NBIs, the PRIMA test facility, which includes a RF-drive ion source with 100 keV accelerator (SPIDER) and a complete 1 MeV Neutral Beam system (MITICA) is under construction at Consorzio RFX in Padova.An experimental validation of the codes has been undertaken in order to prove the accuracy of the simulations and the soundness of the SPIDER and MITICA design. To this purpose, the whole set of codes have been applied to the LHD NBIs in a joint activity between Consorzio RFX and NIFS, with the goal of comparing and benchmarking the codes with the experimental data. A description of these modeling activities and a discussion of the main results obtained are reported in this paper.

  7. Large and negative magnetic anisotropy in pentacoordinate mononuclear Ni(ii) Schiff base complexes.

    PubMed

    Nemec, Ivan; Herchel, Radovan; Svoboda, Ingrid; Boča, Roman; Trávníček, Zdeněk

    2015-05-28

    A series of pentacoordinate Ni(ii) complexes of the general formula [Ni(L5)] () with various pentadentate Schiff base ligands H2L5 (originating in a condensation of aromatic ortho-hydroxy-aldehydes and aliphatic triamines) was synthesized and characterized by X-ray structure analysis and magnetometry. The alternations of substituents on the H2L parent ligand resulted in the complexes with the geometry varying between the square-pyramid and trigonal-bipyramid. In the compounds whose chromophore geometry is closer to a trigonal-bipyramid, a large and negative uniaxial anisotropy (D = -64 cm(-1)) was identified. Moreover, the simple linear expression for the axial zero-field splitting (ZFS) parameter, D/cm(-1) = 32.7(4.8) - 151(10)τ, was proposed, where τ (in degrees) stands for the Addison parameter. The results of magnetic analysis were also supported by ab initio CASSCF/NEVPT2 calculations of the ZFS splitting parameters D and E, and g tensors. Despite large and negative D-values of the reported compounds, slow relaxation of magnetization was not observed either in zero or non-zero static magnetic field, thus no single-molecule magnetic behaviour was detected. PMID:25919125

  8. Large negative linear compressibility of Ag3[Co(CN)6

    PubMed Central

    Goodwin, Andrew L.; Keen, David A.; Tucker, Matthew G.

    2008-01-01

    Silver(I) hexacyanocobaltate(III), Ag3[Co(CN)6], shows a large negative linear compressibility (NLC, linear expansion under hydrostatic pressure) at ambient temperature at all pressures up to our experimental limit of 7.65(2) GPa. This behavior is qualitatively unaffected by a transition at 0.19 GPa to a new phase Ag3[Co(CN)6]-II, whose structure is reported here. The high-pressure phase also shows anisotropic thermal expansion with large uniaxial negative thermal expansion (NTE, expansion on cooling). In both phases, the NLC/NTE effect arises as the rapid compression/contraction of layers of silver atoms—weakly bound via argentophilic interactions—is translated via flexing of the covalent network lattice into an expansion along a perpendicular direction. It is proposed that framework materials that contract along a specific direction on heating while expanding macroscopically will, in general, also expand along the same direction under hydrostatic pressure while contracting macroscopically. PMID:19028875

  9. Generation of solution plasma over a large electrode surface area

    NASA Astrophysics Data System (ADS)

    Saito, Genki; Nakasugi, Yuki; Akiyama, Tomohiro

    2015-07-01

    Solution plasma has been used in a variety of fields such as nanomaterials synthesis, the degradation of harmful substances, and solution analysis. However, as existing methods are ineffective in generating plasma over a large surface area, this study investigated the contact glow discharge electrolysis, in which the plasma was generated on the electrode surface. To clarify the condition of plasma generation, the effect of electrolyte concentration and temperature on plasma formation was studied. The electrical energy needed for plasma generation is higher than that needed to sustain a plasma, and when the electrolyte temperature was increased from 32 to 90 °C at 0.01 M NaOH solution, the electric power density for vapor formation decreased from 2005 to 774 W/cm2. From these results, we determined that pre-warming of the electrolyte is quite effective in generating plasma at lower power density. In addition, lower electrolyte concentrations required higher power density for vapor formation owing to lower solution conductivity. On the basis these results, a method for large-area and flat-plate plasma generation is proposed in which an initial small area of plasma generation is extended. When used with a plate electrode, a concentration of current to the edge of the plate meant that plasma could be formed by covering the edge of the electrode plate.

  10. Lattice thermal transport in large-area polycrystalline graphene

    NASA Astrophysics Data System (ADS)

    Aksamija, Z.; Knezevic, I.

    2014-07-01

    We study lattice thermal transport in large-area polycrystalline graphene, such as the samples grown by chemical vapor deposition (CVD) of carbon on Cu. These systems are composed of single-crystalline grains with a broad range of sizes and crystal orientations, separated by atomically rough grain boundaries. We solve the phonon Boltzmann transport equation and calculate the thermal conductivity in each grain, including scattering from the grain boundary roughness. Thermal transport in the large-area sample is considered in the Corbino-membrane geometry, with heat flowing through a network of thermal resistors and away from a pointlike heat source. The thermal transport in polycrystalline graphene is shown to be highly anisotropic, depending on the individual properties of the grains (their size and boundary roughness), as well as on grain connectivity. Strongest heat conduction occurs along large-grain filaments, while the heat flow is blocked through regions containing predominantly small grains. We discuss how thermal transport in CVD graphene can be tailored by controlling grain disorder.

  11. Electronic hybridization of large-area stacked graphene films.

    PubMed

    Robinson, Jeremy T; Schmucker, Scott W; Diaconescu, C Bogdan; Long, James P; Culbertson, James C; Ohta, Taisuke; Friedman, Adam L; Beechem, Thomas E

    2013-01-22

    Direct, tunable coupling between individually assembled graphene layers is a next step toward designer two-dimensional (2D) crystal systems, with relevance for fundamental studies and technological applications. Here we describe the fabrication and characterization of large-area (>cm(2)), coupled bilayer graphene on SiO(2)/Si substrates. Stacking two graphene films leads to direct electronic interactions between layers, where the resulting film properties are determined by the local twist angle. Polycrystalline bilayer films have a "stained-glass window" appearance explained by the emergence of a narrow absorption band in the visible spectrum that depends on twist angle. Direct measurement of layer orientation via electron diffraction, together with Raman and optical spectroscopy, confirms the persistence of clean interfaces over large areas. Finally, we demonstrate that interlayer coupling can be reversibly turned off through chemical modification, enabling optical-based chemical detection schemes. Together, these results suggest that 2D crystals can be individually assembled to form electronically coupled systems suitable for large-scale applications. PMID:23240977

  12. Development of LAMBDA: Large Area Medipix-Based Detector Array

    NASA Astrophysics Data System (ADS)

    Pennicard, David; Lange, Sabine; Smoljanin, Sergej; Becker, Julian; Hirsemann, Helmut; Epple, Michael; Graafsma, Heinz

    2011-11-01

    The Medipix3 photon counting readout chip has a range of features — small pixel size, high readout rate and inter-pixel communication — which make it attractive for X-ray scattering and imaging at synchrotrons. DESY have produced a prototype large-area detector module that can carry a 6 by 2 array of Medipix3 chips (1536 by 512 pixels), which can be used with a single large silicon sensor (85mm by 28mm) or two ``hexa'' high-Z sensors. The detector head is designed to be tilable and compatible with low temperatures, and will allow high speed parallel readout of the Medipix3 chips. It consists of a ceramic board, on which the sensor assembly is mounted, and a secondary board for signal routing and voltage regulators. A prototype DAQ board using USB2 readout has also been produced. A ``quad'' Medipix3 sensor assembly has been mounted on the detector head, and successfully configured and read out by the DAQ board. Development has begun on a high-speed readout board, and large-area silicon assemblies are in production.

  13. Dark Matter Searches with the Fermi Large Area Telescope

    SciTech Connect

    Meurer, Christine

    2008-12-24

    The Fermi Gamma-Ray Space Telescope, successfully launched on June 11th, 2008, is the next generation satellite experiment for high-energy gamma-ray astronomy. The main instrument, the Fermi Large Area Telescope (LAT), with a wide field of view (>2 sr), a large effective area (>8000 cm{sup 2} at 1 GeV), sub-arcminute source localization, a large energy range (20 MeV-300 GeV) and a good energy resolution (close to 8% at 1 GeV), has excellent potential to either discover or to constrain a Dark Matter signal. The Fermi LAT team pursues complementary searches for signatures of particle Dark Matter in different search regions such as the galactic center, galactic satellites and subhalos, the milky way halo, extragalactic regions as well as the search for spectral lines. In these proceedings we examine the potential of the LAT to detect gamma-rays coming from Weakly Interacting Massive Particle annihilations in these regions with special focus on the galactic center region.

  14. MILDOS-AREA: An enhanced version of MILDOS for large-area sources

    SciTech Connect

    Yuan, Y.C.; Wang, J.H.C.; Zielen, A.

    1989-06-01

    The MILDOS-AREA computer code is a modified version of the MILDOS code, which estimates the radiological impacts of airborne emissions from uranium mining and milling facilities or any other large-area source involving emissions of radioisotopes of the uranium-238 series. MILDOS-AREA is designed for execution on personal computers. The modifications incorporated in the MILDOS-AREA code provide enhanced capabilities for calculating doses from large-area sources and update dosimetry calculations. The major revision from the original MILDOS code is the treatment of atmospheric dispersion from area sources: MILDOS-AREA substitutes a finite element integration approach for the virtual-point method (the algorithm used in the original MILDOS code) when specified by the user. Other revisions include the option of using Martin-Tickvart dispersion coefficients in place of Briggs coefficients for a given source, consideration of plume reflection, and updated internal dosimetry calculations based on the most recent recommendations of the International Commission on Radiation Protection and the age-specific dose calculation methodology developed by Oak Ridge National Laboratory. This report also discusses changes in computer code structure incorporated into MILDOS-AREA, summarizes data input requirements, and provides instructions for installing and using the program on personal computers. 15 refs., 9 figs., 26 tabs.

  15. A three dimensionally position sensitive large area detector

    NASA Astrophysics Data System (ADS)

    Pochodzalla, J.; Butsch, R.; Heck, B.; Hlawatsch, G.; Miczaika, A.; Rabe, H. J.; Rosner, G.

    1985-01-01

    A large area detector consisting of a parallel plate avalanche counter (PPAC) and a trapezohedral ionization chamber (TIC) is described. Its active area is 184 cm 2. The time resolution of the PPAC is 175 ps. The energy resolution of the TIC is 0.4%, the energy loss resolution 2.8%, the nuclear charge resolution 2.3%. The TIC is position sensitive in three dimensions. The position x is measured via a saw-tooth anode with a resolution of 0.7 mm; the drift time coordinate shows a resolution of δy ≅ mm. The range z is determined by a new technique, a graded density Frisch grid. It enlarges the dynamic range of the charge measurement down to the Bragg maximum at E/ A ˜ 1 MeV. The resolution is δZ/ Z ≅ 3.5%

  16. Large Area Crop Inventory Experiment (LACIE). Phase 2 evaluation report

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Documentation of the activities of the Large Area Crop Inventory Experiment during the 1976 Northern Hemisphere crop year is presented. A brief overview of the experiment is included as well as phase two area, yield, and production estimates for the United States Great Plains, Canada, and the Union of Soviet Socialist Republics spring winter wheat regions. The accuracies of these estimates are compared with independent government estimates. Accuracy assessment of the United States Great Plains yardstick region based on a through blind sight analysis is given, and reasons for variations in estimating performance are discussed. Other phase two technical activities including operations, exploratory analysis, reporting, methods of assessment, phase three and advanced system design, technical issues, and developmental activities are also included.

  17. Accuracy assessment in the Large Area Crop Inventory Experiment

    NASA Technical Reports Server (NTRS)

    Houston, A. G.; Pitts, D. E.; Feiveson, A. H.; Badhwar, G.; Ferguson, M.; Hsu, E.; Potter, J.; Chhikara, R.; Rader, M.; Ahlers, C.

    1979-01-01

    The Accuracy Assessment System (AAS) of the Large Area Crop Inventory Experiment (LACIE) was responsible for determining the accuracy and reliability of LACIE estimates of wheat production, area, and yield, made at regular intervals throughout the crop season, and for investigating the various LACIE error sources, quantifying these errors, and relating them to their causes. Some results of using the AAS during the three years of LACIE are reviewed. As the program culminated, AAS was able not only to meet the goal of obtaining accurate statistical estimates of sampling and classification accuracy, but also the goal of evaluating component labeling errors. Furthermore, the ground-truth data processing matured from collecting data for one crop (small grains) to collecting, quality-checking, and archiving data for all crops in a LACIE small segment.

  18. A large-area gamma-ray imaging telescope system

    NASA Technical Reports Server (NTRS)

    Koch, D. G.

    1983-01-01

    The concept definition of using the External Tank (ET) of the Space Shuttle as the basis for constructing a large area gamma ray imaging telescope in space is detailed. The telescope will be used to locate and study cosmic sources of gamma rays of energy greater than 100 MeV. Both the telescope properties and the means whereby an ET is used for this purpose are described. A parallel is drawn between those systems that would be common to both a Space Station and this ET application. In addition, those systems necessary for support of the telescope can form the basis for using the ET as part of the Space Station. The major conclusions of this concept definition are that the ET is ideal for making into a gamma ray telescope, and that this telescope will provide a substantial increase in collecting area.

  19. Large area low-cost space solar cell development

    NASA Technical Reports Server (NTRS)

    Baraona, C. R.; Cioni, J. L.

    1982-01-01

    A development program to produce large-area (5.9 x 5.9 cm) space quality silicon solar cells with a cost goal of 30 $/watt is descibed. Five cell types under investigation include wraparound dielectric, mechanical wraparound and conventional contact configurations with combinations of 2 or 10 ohm-cm resistivity, back surface reflectors and/or fields, and diffused or ion implanted junctions. A single step process to cut cell and cover-glass simultaneously is being developed. A description of cell developments by Applied Solar Energy Corp., Spectrolab and Spire is included. Results are given for cell and array tests, performed by Lockheed, TRW and NASA. Future large solar arrays that might use cells of this type are discussed.

  20. Large-area Kapton x-ray windows

    NASA Astrophysics Data System (ADS)

    Antimonov, M.; Khounsary, A.; Weigand, S.; Rix, J.; Keane, D.; Grudzinski, J. J.; Johnson, A.; Zhou, Z.; Jansma, W.

    2015-09-01

    Some X-ray instruments require the utilization of large-area windows to provide vacuum barriers. The necessary attributes of the window material include transparency to X-rays, low scattering, and possession of suitable mechanical properties for reliable long-term performance. Kapton is one such material except that it is a polymer and a large window made from Kapton with a pressure differential of one atmosphere across it can undergo substantial deformation at room temperature. In this paper, we report on the mechanical testing of Kapton samples including creep measurements, and comparison with published data. We use of these data together with analytical / numerical models to predict the changes in the profile of Kapton vacuum windows over time, and show good agreement with experimental measurements.

  1. Large area photodetector based on microwave cavity perturbation techniques

    SciTech Connect

    Braggio, C. Carugno, G.; Sirugudu, R. K.; Lombardi, A.; Ruoso, G.

    2014-07-28

    We present a preliminary study to develop a large area photodetector, based on a semiconductor crystal placed inside a superconducting resonant cavity. Laser pulses are detected through a variation of the cavity impedance, as a consequence of the conductivity change in the semiconductor. A novel method, whereby the designed photodetector is simulated by finite element analysis, makes it possible to perform pulse-height spectroscopy on the reflected microwave signals. We measure an energy sensitivity of 100 fJ in the average mode without the employment of low noise electronics and suggest possible ways to further reduce the single-shot detection threshold, based on the results of the described method.

  2. Large area nuclear particle detectors using ET materials

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The purpose of this SBIR Phase 1 feasibility effort was to demonstrate the usefulness of Quantex electron-trapping (ET) materials for spatial detection of nuclear particles over large areas. This demonstration entailed evaluating the prompt visible scintillation as nuclear particles impinged on films of ET materials, and subsequently detecting the nuclear particle impingement information pattern stored in the ET material, by means of the visible-wavelength luminescence produced by near-infrared interrogation. Readily useful levels of scintillation and luminescence outputs are demonstrated.

  3. Route to create large-area ordered polymeric nanochannel arrays

    NASA Astrophysics Data System (ADS)

    Müller-Buschbaum, P.; Bauer, E.; Maurer, E.; Schlögl, K.; Roth, S. V.; Gehrke, R.

    2006-02-01

    Depositing polymdimethylsiloxane (PDMS) from an isopropanol solution onto a glass slide surface by wiping with a fuzz-free wipe results in highly ordered structures. Dewetting of the highly diluted PDMS solution and evaporation of the solvent yields nanostructures. The structure is well characterized as polymer nanochannels, separated by a mean distance of 166nm. The mean height of the shallow channels is 3nm only. The proof of having aligned structures on very large surface areas with a well defined orientation is performed with a very high resolution grazing incidence small angle x-ray scattering setup.

  4. Position reconstruction in large-area scintillating fibre detectors

    NASA Astrophysics Data System (ADS)

    Mahata, K.; Johansson, H. T.; Paschalis, S.; Simon, H.; Aumann, T.

    2009-09-01

    A new analysis procedure has been developed for the large-area scintillating fibre detectors with position-sensitive photomultiplier (PSPM) readout used for heavy ions in the LAND set-up at GSI. It includes gain matching of the PSPM, calibration of the PSPM fibre mask and hit reconstruction. This procedure allows for a quasi-online calibration of this tracking device. It also allows for a precise determination of the position close to the intrinsic detector resolution of 1 mm pitch together with careful treatment of individual event accuracies.

  5. Method of manufacturing a large-area segmented photovoltaic module

    DOEpatents

    Lenox, Carl

    2013-11-05

    One embodiment of the invention relates to a segmented photovoltaic (PV) module which is manufactured from laminate segments. The segmented PV module includes rectangular-shaped laminate segments formed from rectangular-shaped PV laminates and further includes non-rectangular-shaped laminate segments formed from rectangular-shaped and approximately-triangular-shaped PV laminates. The laminate segments are mechanically joined and electrically interconnected to form the segmented module. Another embodiment relates to a method of manufacturing a large-area segmented photovoltaic module from laminate segments of various shapes. Other embodiments relate to processes for providing a photovoltaic array for installation at a site. Other embodiments and features are also disclosed.

  6. Large Area Crop Inventory Experiment (LACIE). Executive summary

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The author has identified the following significant results. The Large Area Crop Inventory Experiment (LACIE), completed June 30, 1978, has met the USDA at-harvest goals (90% accuracy with a 90% confidence level) in the US Great Plains and U.S.S.R. for two consecutive years. In addition, in the U.S.S.R., LACIE indicated a shortfall in the '76-'77 wheat crop about two months prior to harvest, thus demonstrating the capability of LACIE to make accurate preharvest estimates.

  7. High-Throughput Dry Processes for Large-Area Devices

    SciTech Connect

    BUSS,RICHARD J.; HEBNER,GREGORY A.; RUBY,DOUGLAS S.; YANG,PIN

    1999-11-01

    In October 1996, an interdisciplinary team began a three-year LDRD project to study the plasma processes of reactive ion etching and plasma-enhanced chemical vapor deposition on large-area silicon devices. The goal was to develop numerical models that could be used in a variety of applications for surface cleaning, selective etching, and thin-film deposition. Silicon solar cells were chosen as the experimental vehicle for this project because an innovative device design was identified that would benefit from immediate performance improvement using a combination of plasma etching and deposition processes. This report presents a summary of the technical accomplishments and conclusions of the team.

  8. LACIE large area acreage estimation. [United States of America

    NASA Technical Reports Server (NTRS)

    Chhikara, R. S.; Feiveson, A. H. (Principal Investigator)

    1979-01-01

    A sample wheat acreage for a large area is obtained by multiplying its small grains acreage estimate as computed by the classification and mensuration subsystem by the best available ratio of wheat to small grains acreages obtained from historical data. In the United States, as in other countries with detailed historical data, an additional level of aggregation was required because sample allocation was made at the substratum level. The essential features of the estimation procedure for LACIE countries are included along with procedures for estimating wheat acreage in the United States.

  9. Fermi Large Area Telescope Bright Gamma-ray Source List

    SciTech Connect

    Abdo, Aous A.; Ackermann, M.; Ajello, M.; Atwood, W.B.; Axelsson, M.; Baldini, L.; Ballet, J.; Band, D.L.; Barbiellini, Guido; Bastieri, Denis; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bignami, G.F.; Bloom, Elliott D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brigida, M.; Bruel, P.; Burnett, Thompson H.; /more authors..

    2009-05-15

    Following its launch in 2008 June, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in three months produced a deeper and better resolved map of the {gamma}-ray sky than any previous space mission. We present here initial results for energies above 100 MeV for the 205 most significant (statistical significance greater than {approx}10{sigma}) {gamma}-ray sources in these data. These are the best characterized and best localized point-like (i.e., spatially unresolved) {gamma}-ray sources in the early mission data.

  10. Large-area settlement pattern recognition from Landsat-8 data

    NASA Astrophysics Data System (ADS)

    Wieland, Marc; Pittore, Massimiliano

    2016-09-01

    The study presents an image processing and analysis pipeline that combines object-based image analysis with a Support Vector Machine to derive a multi-layered settlement product from Landsat-8 data over large areas. 43 image scenes are processed over large parts of Central Asia (Southern Kazakhstan, Kyrgyzstan, Tajikistan and Eastern Uzbekistan). The main tasks tackled by this work include built-up area identification, settlement type classification and urban structure types pattern recognition. Besides commonly used accuracy assessments of the resulting map products, thorough performance evaluations are carried out under varying conditions to tune algorithm parameters and assess their applicability for the given tasks. As part of this, several research questions are being addressed. In particular the influence of the improved spatial and spectral resolution of Landsat-8 on the SVM performance to identify built-up areas and urban structure types are evaluated. Also the influence of an extended feature space including digital elevation model features is tested for mountainous regions. Moreover, the spatial distribution of classification uncertainties is analyzed and compared to the heterogeneity of the building stock within the computational unit of the segments. The study concludes that the information content of Landsat-8 images is sufficient for the tested classification tasks and even detailed urban structures could be extracted with satisfying accuracy. Freely available ancillary settlement point location data could further improve the built-up area classification. Digital elevation features and pan-sharpening could, however, not significantly improve the classification results. The study highlights the importance of dynamically tuned classifier parameters, and underlines the use of Shannon entropy computed from the soft answers of the SVM as a valid measure of the spatial distribution of classification uncertainties.

  11. Large area x-ray detectors for cargo radiography

    NASA Astrophysics Data System (ADS)

    Bueno, C.; Albagli, D.; Bendahan, J.; Castleberry, D.; Gordon, C.; Hopkins, F.; Ross, W.

    2007-04-01

    Large area x-ray detectors based on phosphors coupled to flat panel amorphous silicon diode technology offer significant advances for cargo radiologic imaging. Flat panel area detectors provide large object coverage offering high throughput inspections to meet the high flow rate of container commerce. These detectors provide excellent spatial resolution when needed, and enhanced SNR through low noise electronics. If the resolution is reduced through pixel binning, further advances in SNR are achievable. Extended exposure imaging and frame averaging enables improved x-ray penetration of ultra-thick objects, or "select-your-own" contrast sensitivity at a rate many times faster than LDAs. The areal coverage of flat panel technology provides inherent volumetric imaging with the appropriate scanning methods. Flat panel area detectors have flexible designs in terms of electronic control, scintillator selection, pixel pitch, and frame rates. Their cost is becoming more competitive as production ramps up for the healthcare, nondestructive testing (NDT), and homeland protection industries. Typically used medical and industrial polycrystalline phosphor materials such as Gd2O2S:Tb (GOS) can be applied to megavolt applications if the phosphor layer is sufficiently thick to enhance x-ray absorption, and if a metal radiator is used to augment the quantum detection efficiency and reduce x-ray scatter. Phosphor layers ranging from 0.2-mm to 1-mm can be "sandwiched" between amorphous silicon flat panel diode arrays and metal radiators. Metal plates consisting of W, Pb or Cu, with thicknesses ranging from 0.25-mm to well over 1-mm can be used by covering the entire area of the phosphor plate. In some combinations of high density metal and phosphor layers, the metal plate provides an intensification of 25% in signal due to electron emission from the plate and subsequent excitation within the phosphor material. This further improves the SNR of the system.

  12. Ultraflexible, large-area, physiological temperature sensors for multipoint measurements

    PubMed Central

    Yokota, Tomoyuki; Inoue, Yusuke; Terakawa, Yuki; Reeder, Jonathan; Kaltenbrunner, Martin; Ware, Taylor; Yang, Kejia; Mabuchi, Kunihiko; Murakawa, Tomohiro; Sekino, Masaki; Voit, Walter; Sekitani, Tsuyoshi; Someya, Takao

    2015-01-01

    We report a fabrication method for flexible and printable thermal sensors based on composites of semicrystalline acrylate polymers and graphite with a high sensitivity of 20 mK and a high-speed response time of less than 100 ms. These devices exhibit large resistance changes near body temperature under physiological conditions with high repeatability (1,800 times). Device performance is largely unaffected by bending to radii below 700 µm, which allows for conformal application to the surface of living tissue. The sensing temperature can be tuned between 25 °C and 50 °C, which covers all relevant physiological temperatures. Furthermore, we demonstrate flexible active-matrix thermal sensors which can resolve spatial temperature gradients over a large area. With this flexible ultrasensitive temperature sensor we succeeded in the in vivo measurement of cyclic temperatures changes of 0.1 °C in a rat lung during breathing, without interference from constant tissue motion. This result conclusively shows that the lung of a warm-blooded animal maintains surprising temperature stability despite the large difference between core temperature and inhaled air temperature. PMID:26554008

  13. An advanced open path atmospheric pollution monitor for large areas

    SciTech Connect

    Taylor, L.; Suhre, D.; Mani, S.

    1996-12-31

    Over 100 million gallons of radioactive and toxic waste materials generated in weapon materials production are stored in 322 tanks buried within large areas at DOE sites. Toxic vapors occur in the tank headspace due to the solvents used and chemical reactions within the tanks. To prevent flammable or explosive concentration of volatile vapors, the headspace are vented, either manually or automatically, to the atmosphere when the headspace pressure exceeds preset values. Furthermore, 67 of the 177 tanks at the DOE Hanford Site are suspected or are known to be leaking into the ground. These underground storage tanks are grouped into tank farms which contain closely spaced tanks in areas as large as 1 km{sup 2}. The objective of this program is to protect DOE personnel and the public by monitoring the air above these tank farms for toxic air pollutants without the monitor entering the tanks farms, which can be radioactive. A secondary objective is to protect personnel by monitoring the air above buried 50 gallon drums containing moderately low radioactive materials but which could also emit toxic air pollutants.

  14. Exfoliation of large-area transition metal chalcogenide single layers

    PubMed Central

    Magda, Gábor Zsolt; Pető, János; Dobrik, Gergely; Hwang, Chanyong; Biró, László P.; Tapasztó, Levente

    2015-01-01

    Isolating large-areas of atomically thin transition metal chalcogenide crystals is an important but challenging task. The mechanical exfoliation technique can provide single layers of the highest structural quality, enabling to study their pristine properties and ultimate device performance. However, a major drawback of the technique is the low yield and small (typically < 10 μm) lateral size of the produced single layers. Here, we report a novel mechanical exfoliation technique, based on chemically enhanced adhesion, yielding MoS2 single layers with typical lateral sizes of several hundreds of microns. The idea is to exploit the chemical affinity of the sulfur atoms that can bind more strongly to a gold surface than the neighboring layers of the bulk MoS2 crystal. Moreover, we found that our exfoliation process is not specific to MoS2, but can be generally applied for various layered chalcogenides including selenites and tellurides, providing an easy access to large-area 2D crystals for the whole class of layered transition metal chalcogenides. PMID:26443185

  15. Development of a Large-Area Ultracold Neutron Detector

    NASA Astrophysics Data System (ADS)

    Stoffel, Jenna; Liu, Chen-Yu; UCN Tau Collaboration

    2015-10-01

    To improve our knowledge in particle physics and cosmology, including big-bang nucleosynthesis, we need a more precise and accurate measurement of the lifetime of free neutrons. Though there have been many attempts to measure the neutron lifetime, discrepancies exist between the two major experimental techniques of the beam and the bottle methods. To resolve this discrepancy, the UCN τ experiment will trap ultracold neutrons (UCNs) to perform lifetime measurements to the 1-second level. To accomplish this goal, we are developing a large-area, high-efficiency UCN detector. We construct a scintillating UCN detector by evaporating a thin film of boron-10 onto an airbrushed layer of zinc sulfide (ZnS); the 10B-coated ZnS scintillating film is then glued to wavelength-shifting plastic, which acts as a light guide to direct photons into modern silicon photomultipliers. This new detector has similar efficiency and background noise as the previously-used ion gas detectors, but can be easily scaled up to cover large areas for many applications. The new detector opens up exciting new ways to study systematic effects, as they hold the key to the interpretation of neutron lifetime.

  16. Scaling Up Nature: Large Area Flexible Biomimetic Surfaces.

    PubMed

    Li, Yinyong; John, Jacob; Kolewe, Kristopher W; Schiffman, Jessica D; Carter, Kenneth R

    2015-10-28

    The fabrication and advanced function of large area biomimetic superhydrophobic surfaces (SHS) and slippery lubricant-infused porous surfaces (SLIPS) are reported. The use of roll-to-roll nanoimprinting techniques enabled the continuous fabrication of SHS and SLIPS based on hierarchically wrinkled surfaces. Perfluoropolyether hybrid molds were used as flexible molds for roll-to-roll imprinting into a newly designed thiol-ene based photopolymer resin coated on flexible polyethylene terephthalate films. The patterned surfaces exhibit feasible superhydrophobicity with a water contact angle around 160° without any further surface modification. The SHS can be easily converted into SLIPS by roll-to-roll coating of a fluorinated lubricant, and these surfaces have outstanding repellence to a variety of liquids. Furthermore, both SHS and SLIPS display antibiofouling properties when challenged with Escherichia coli K12 MG1655. The current article describes the transformation of artificial biomimetic structures from small, lab-scale coupons to low-cost, large area platforms. PMID:26423494

  17. Simulations of Large-Area Electron Beam Diodes

    NASA Astrophysics Data System (ADS)

    Swanekamp, S. B.; Friedman, M.; Ludeking, L.; Smithe, D.; Obenschain, S. P.

    1999-11-01

    Large area electron beam diodes are typically used to pump the amplifiers of KrF lasers. Simulations of large-area electron beam diodes using the particle-in-cell code MAGIC3D have shown the electron flow in the diode to be unstable. Since this instability can potentially produce a non-uniform current and energy distribution in the hibachi structure and lasing medium it can be detrimental to laser efficiency. These results are similar to simulations performed using the ISIS code.(M.E. Jones and V.A. Thomas, Proceedings of the 8^th) International Conference on High-Power Particle Beams, 665 (1990). We have identified the instability as the so called ``transit-time" instability(C.K. Birdsall and W.B. Bridges, Electrodynamics of Diode Regions), (Academic Press, New York, 1966).^,(T.M. Antonsen, W.H. Miner, E. Ott, and A.T. Drobot, Phys. Fluids 27), 1257 (1984). and have investigated the role of the applied magnetic field and diode geometry. Experiments are underway to characterize the instability on the Nike KrF laser system and will be compared to simulation. Also some possible ways to mitigate the instability will be presented.

  18. Large-Area Zone Plate Fabrication with Optical Lithography

    SciTech Connect

    Denbeaux, G.

    2011-09-09

    Zone plates as condenser optics for x-ray microscopes offer simple optical designs for both illumination and spectral resolution when used as a linear monochromator. However, due to the long write times for electron beam lithography, both the availability and the size of zone plates for condensers have been limited. Since the resolution provided by the linear monochromator scales almost linearly with the diameter of the zone plate, the full potential for zone plate monochromators as illumination systems for x-ray microscopes has not been achieved. For example, the 10-mm-diameter zone plate has demonstrated a spectral resolution of E/{Delta}E = 700[1], but with a 26-mm-diameter zone plate, the calculated spectral resolution is higher than E/{Delta}E = 3000. These large-area zone plates are possible to fabricate with the leading edge semiconductor lithography tools such as those available at the College of Nanoscale Science and Engineering at the University at Albany. One of the lithography tools available is the ASML TWINSCAN XT: 1950i with 37-nm resolution [2]. A single 300-mm wafer can contain more than 60 fields, each with a large area condenser, and the throughput of the tool can be more than one wafer every minute.

  19. The GLAST Large Area Telescope Detector Performance Monitoring

    SciTech Connect

    Borgland, A.W.; Charles, E.; /SLAC

    2007-10-16

    The Large Area Telescope (LAT) is one of two instruments on board the Gamma-ray Large Area Telescope (GLAST), the next generation high energy gamma-ray space telescope. The LAT contains sixteen identical towers in a four-by-four grid. Each tower contains a silicon-strip tracker and a CsI calorimeter that together will give the incident direction and energy of the pair-converting photon in the energy range 20 MeV - 300 GeV. In addition, the instrument is covered by a finely segmented Anti-Coincidence Detector (ACD) to reject charged particle background. Altogether, the LAT contains more than 864k channels in the trackers, 1536 CsI crystals and 97 ACD plastic scintillator tiles and ribbons. Here we detail some of the strategies and methods for how we are planning to monitor the instrument performance on orbit. It builds on the extensive experience gained from Integration & Test and Commissioning of the instrument on ground.

  20. Prospects for Pulsar Studies with the GLAST Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    2007-01-01

    The Large Area Telescope (LAT) on the Gamma-ray Large Area Space Telescope (GLAST), due to launch in November 2007, will have unprecedented sensitivity and energy resolution for gamma-rays in the range of 30 MeV to 200 GeV. GLAST is therefore expected to provide major advances in the understanding of high-energy emission from rotation-powered pulsars. As the only presently known galactic GeV source class; pulsars will be one of the most important sources for study with GLAST. The main science goals of the LAT for pulsar studies include an increase in the number of detected radio-loud and radio-quiet gamma-ray pulsars, including millisecond pulsars, giving much better statistics for elucidating population characteristics, measurement of the high-energy spectrum and the shape of spectral cutoffs and determining pulse profiles for a variety of pulsars of different age. Further, measurement of phase-resolved spectra and energy dependent pulse profiles of the brighter pulsars should allow detailed tests of magnetospheric particle acceleration and radiation mechanisms, by comparing data with theoretical models that have been developed. Additionally, the LAT will have the sensitivity to allow blind pulsation searches of nearly all unidentified EGRET sources, to possibly uncover more radio-quiet Geminga-like pulsars.

  1. Prospects for Pulsar Studies with the GLAST Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    2007-01-01

    The Large Area Telescope (LAT) on the Gamma-ray Large Area Space Telescope (GLAST), due to launch in November 2007, will have unprecedented sensitivity and energy resolution for gamma-rays in the range of 30 MeV to 200 GeV. GLAST is therefore expected to provide major advances in the understanding of high-energy emission from rotation-powered p ulsars. As the only presently known galactic GeV source class, pulsar s will be one of the most important sources for study with GLAST. The main science goals of the LAT for pulsar studies include an increase in the number of detected radio-loud and radio-quiet gamma-ray pulsar s, including millisecond pulsars, giving much better statistics for e lucidating population characteristics, measurement of the high-energy spectrum and the shape of spectral cutoffs and determining pulse profiles for a variety of pulsars of different age. Further, measurement of phase-resolved spectra and energy dependent pulse profiles of the brighter pulsars should allow detailed tests of magnetospheric partic le acceleration and radiation mechanisms, by comparing data with theo retical models that have been developed. Additionally, the LAT will have the sensitivity to allow blind pulsation searches of nearly all un identified EGRET sources, to possibly uncover more radio-quiet Geming a-like pulsars.

  2. Prospects for Pulsar Studies with the GLAST Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    2006-01-01

    The Large Area Telescope (LAT) on the Gamma-ray Large Area Space Telescope (GLAST) will have unprecedented sensitivity and energy resolution for gamma-rays in the range of 30 MeV to 200 GeV. GLAST is therefore expected to provide major advances in the understanding of high-energy emission from rotation-powered pulsars. As the only presently known galactic GeV source class, pulsars will be one of the most important sources for study with GLAST. The main science goals of the LAT for pulsar studies include an increase in the number of detected radio-loud and radio-quiet gamma ray pulsars, including millisecond pulsars, giving much better statistics for elucidating population characteristics, measurement of the high-energy spectrum and the shape of spectral cutoffs and determining pulse profiles for a variety of pulsars of different age. Further, measurement of phase-resolved spectra and energy dependent pulse profiles of the brighter pulsars should allow detailed tests of magnetospheric particle acceleration and radiation mechanisms, by comparing data with theoretical models that have been developed. Additionally, the LAT will have the sensitivity to allow blind pulsation searches of nearly all unidentified EGRET sources, to possibly uncover more radio-quiet Geminga-like pulsars.

  3. Human Discs Large Is a New Negative Regulator of Human Immunodeficiency Virus-1 Infectivity

    PubMed Central

    Perugi, Fabien; Muriaux, Delphine; Ramirez, Bertha Cecilia; Chabani, Sabah; Decroly, Etienne; Darlix, Jean-Luc; Blot, Vincent

    2009-01-01

    Human immunodeficiency virus (HIV)-1 replication is positively or negatively regulated through multiple interactions with host cell proteins. We report here that human Discs Large (Dlg1), a scaffold protein recruited beneath the plasma membrane and involved in the assembly of multiprotein complexes, restricts HIV-1 infectivity. The endogenous Dlg1 and HIV-1 Gag polyprotein spontaneously interact in HIV-1-chronically infected T cells. Depleting endogenous Dlg1 in either adherent cells or T cells does not affect Gag maturation, production, or release, but it enhances the infectivity of progeny viruses five- to sixfold. Conversely, overexpression of Dlg1 reduces virus infectivity by ∼80%. Higher virus infectivity upon Dlg1 depletion correlates with increased Env content in cells and virions, whereas the amount of virus-associated Gag or genomic RNA remains identical. Dlg1 knockdown is also associated with the redistribution and colocalization of Gag and Env toward CD63 and CD82 positive vesicle-like structures, including structures that seem to still be connected to the plasma membrane. This study identifies both a new negative regulator that targets the very late steps of the HIV-1 life cycle, and an assembly pathway that optimizes HIV-1 infectivity. PMID:18946087

  4. Large-Area Epitaxial Monolayer MoS2

    PubMed Central

    2015-01-01

    Two-dimensional semiconductors such as MoS2 are an emerging material family with wide-ranging potential applications in electronics, optoelectronics, and energy harvesting. Large-area growth methods are needed to open the way to applications. Control over lattice orientation during growth remains a challenge. This is needed to minimize or even avoid the formation of grain boundaries, detrimental to electrical, optical, and mechanical properties of MoS2 and other 2D semiconductors. Here, we report on the growth of high-quality monolayer MoS2 with control over lattice orientation. We show that the monolayer film is composed of coalescing single islands with limited numbers of lattice orientation due to an epitaxial growth mechanism. Optical absorbance spectra acquired over large areas show significant absorbance in the high-energy part of the spectrum, indicating that MoS2 could also be interesting for harvesting this region of the solar spectrum and fabrication of UV-sensitive photodetectors. Even though the interaction between the growth substrate and MoS2 is strong enough to induce lattice alignment via van der Waals interaction, we can easily transfer the grown material and fabricate devices. Local potential mapping along channels in field-effect transistors shows that the single-crystal MoS2 grains in our film are well connected, with interfaces that do not degrade the electrical conductivity. This is also confirmed by the relatively large and length-independent mobility in devices with a channel length reaching 80 μm. PMID:25843548

  5. Large-Area Epitaxial Monolayer MoS2.

    PubMed

    Dumcenco, Dumitru; Ovchinnikov, Dmitry; Marinov, Kolyo; Lazić, Predrag; Gibertini, Marco; Marzari, Nicola; Lopez Sanchez, Oriol; Kung, Yen-Cheng; Krasnozhon, Daria; Chen, Ming-Wei; Bertolazzi, Simone; Gillet, Philippe; Fontcuberta i Morral, Anna; Radenovic, Aleksandra; Kis, Andras

    2015-04-28

    Two-dimensional semiconductors such as MoS2 are an emerging material family with wide-ranging potential applications in electronics, optoelectronics, and energy harvesting. Large-area growth methods are needed to open the way to applications. Control over lattice orientation during growth remains a challenge. This is needed to minimize or even avoid the formation of grain boundaries, detrimental to electrical, optical, and mechanical properties of MoS2 and other 2D semiconductors. Here, we report on the growth of high-quality monolayer MoS2 with control over lattice orientation. We show that the monolayer film is composed of coalescing single islands with limited numbers of lattice orientation due to an epitaxial growth mechanism. Optical absorbance spectra acquired over large areas show significant absorbance in the high-energy part of the spectrum, indicating that MoS2 could also be interesting for harvesting this region of the solar spectrum and fabrication of UV-sensitive photodetectors. Even though the interaction between the growth substrate and MoS2 is strong enough to induce lattice alignment via van der Waals interaction, we can easily transfer the grown material and fabricate devices. Local potential mapping along channels in field-effect transistors shows that the single-crystal MoS2 grains in our film are well connected, with interfaces that do not degrade the electrical conductivity. This is also confirmed by the relatively large and length-independent mobility in devices with a channel length reaching 80 μm. PMID:25843548

  6. High-efficiency, large-area CdTe panels

    NASA Astrophysics Data System (ADS)

    Albright, S. P.; Singh, V. P.; Ackerman, B.

    1989-04-01

    This technical progress report on large-area CdTe solar panels cover work accomplished from June 1987 to May 1988. The highest-efficiency devices produced during this period measured 10.6 percent efficient on a 0.302-cm(2) cell. On 11-7/8 in. by 12 in. panels, the highest output obtained was 5.3 W over 847 cm(2), or 7.0 percent active-area efficiency. The aperture-area efficiency is presently about 12 percent lower, or 6.3 percent efficiency, because of interconnection losses. A 4-ft(2) panel was also produced. Resistivities of less than 100 ohm-cm have been observed consistently in phosphorus- or copper-doped CdTe. Surface analysis is presented for various CdTe treatments. Devices were characterized and analyzed using electron-beam-induced current, capacitance, spectral response, and I-V curves at various temperatures. A model for junction transport is presented. An encapsulation system is described, and lifetime test results are presented.

  7. SPLASH: A Southern Parkes Large Area Survey in Hydroxyl

    NASA Astrophysics Data System (ADS)

    Dawson, Joanne; Caswell, James; Gomez, Jose F.; Mcclure-Griffiths, Naomi; Lo, Nadia; Jones, Paul; Dickey, John; Cunningham, Maria; Green, James; Carretti, Ettore; Ellingsen, Simon; Walsh, Andrew; Purcell, Cormac; Breen, Shari; Hennebelle, Patrick; Imai, Hiroshi; Lowe, Vicki; Gibson, Steven; Jones, Courtney; Krishnan, Vasaant

    2013-10-01

    The OH 18 cm lines are powerful and versatile probes of diffuse molecular gas, that may trace a largely unstudied component of the Galactic ISM. SPLASH (the Southern Parkes Large Area Survey in Hydroxyl) is a large, unbiased and fully-sampled survey of OH emission, absorption and masers in the Galactic Plane that will achieve sensitivities an order of magnitude better than previous work. The survey will answer critical questions on the global distribution of diffuse OH, the degree to which it traces ‘hidden’ material caught between the regimes probed by traditional tracers of the neutral ISM, and its role as a probe of molecular cloud formation. As a blind survey for all four ground-state transitions, SPLASH will also detect many new OH masers, facilitating a broad range of astrophysical studies. This proposal requests 670 hours spread over two semesters to complete Phase 1 of the SPLASH project, which will map 152 square degrees in the inner Galactic Plane, including the Galactic Centre. Following the ongoing success of the project, we request that its pre-graded status be renewed for a final two semesters.

  8. Ultra-stiff large-area carpets of carbon nanotubes.

    PubMed

    Meysami, Seyyed Shayan; Dallas, Panagiotis; Britton, Jude; Lozano, Juan G; Murdock, Adrian T; Ferraro, Claudio; Gutierrez, Eduardo Saiz; Rijnveld, Niek; Holdway, Philip; Porfyrakis, Kyriakos; Grobert, Nicole

    2016-06-01

    Herewith, we report the influence of post-synthesis heat treatment (≤2350 °C and plasma temperatures) on the crystal structure, defect density, purity, alignment and dispersibility of free-standing large-area (several cm(2)) carpets of ultra-long (several mm) vertically aligned multi-wall carbon nanotubes (VA-MWCNTs). VA-MWCNTs were produced in large quantities (20-30 g per batch) using a semi-scaled-up aerosol-assisted chemical vapour deposition (AACVD) setup. Electron and X-ray diffraction showed that the heat treatment at 2350 °C under inert atmosphere purifies, removes residual catalyst particles, and partially aligns adjacent single crystals (crystallites) in polycrystalline MWCNTs. The purification and improvement in the crystallites alignment within the MWCNTs resulted in reduced dispersibility of the VA-MWCNTs in liquid media. High-resolution microscopy revealed that the crystallinity is improved in scales of few tens of nanometres while the point defects remain largely unaffected. The heat treatment also had a marked benefit on the mechanical properties of the carpets. For the first time, we report compression moduli as high as 120 MPa for VA-MWCNT carpets, i.e. an order of magnitude higher than previously reported figures. The application of higher temperatures (arc-discharge plasma, ≥4000 °C) resulted in the formation of a novel graphite-matrix composite reinforced with CVD and arc-discharge-like carbon nanotubes. PMID:27240959

  9. GLAST, the Gamma-ray Large Area Space Telescope

    NASA Technical Reports Server (NTRS)

    Ritz, Steven

    2007-01-01

    The Gamma-ray Large Area Space Telescope, GLAST, is a mission to measure the cosmic gamma-ray flux in the energy range 20 MeV to greater than 300 GeV, with supporting measurements for gamma-ray bursts from 10 keV to 25 MeV. With its upcoming launch in 2008, GLAST will open a new and important window on a wide variety of phenomena, including black holes and active galactic nuclei; the optical-UV extragalactic background light, gamma-ray bursts; the origin of cosmic rays and supernova remnants; and searches for hypothetical new phenomena such as supersymmetric dark matter annihilations and Lorentz invariance violation. In addition to the science opportunities, this talk includes a description of the instruments, the collaboration between particle physicists and astrophysicists, the opportunities for guest observers, and the mission status.

  10. Large area nuclear particle detectors using ET materials, phase 2

    NASA Technical Reports Server (NTRS)

    Wrigley, Charles Y.; Storti, George M.; Walter, Lee; Mathews, Scott

    1990-01-01

    This report presents work done under a Phase 2 SBIR contract for demonstrating large area detector planes utilizing Quantex electron trapping materials as a film medium for storing high-energy nuclide impingement information. The detector planes utilize energy dissipated by passage of the high-energy nuclides to produce localized populations of electrons stored in traps. Readout of the localized trapped electron populations is effected by scanning the ET plane with near-infrared, which frees the trapped electrons and results in optical emission at visible wavelengths. The effort involved both optimizing fabrication technology for the detector planes and developing a readout system capable of high spatial resolution for displaying the recorded nuclide passage tracks.

  11. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF GRB 110625A

    SciTech Connect

    Tam, P. H. T.; Kong, A. K. H.; Fan Yizhong

    2012-08-01

    Gamma-ray bursts (GRBs) that emit photons at GeV energies form a small but significant population of GRBs. However, the number of GRBs whose GeV-emitting period is simultaneously observed in X-rays remains small. We report {gamma}-ray observations of GRB 110625A using Fermi's Large Area Telescope in the energy range 100 MeV-20 GeV. Gamma-ray emission at these energies was clearly detected using data taken between 180 s and 580 s after the burst, an epoch after the prompt emission phase. The GeV light curve differs from a simple power-law decay, and probably consists of two emission periods. Simultaneous Swift X-Ray Telescope observations did not show flaring behaviors as in the case of GRB 100728A. We discuss the possibility that the GeV emission is the synchrotron self-Compton radiation of underlying ultraviolet flares.

  12. Broadband quasi-optical SIS mixers with large area junctions

    NASA Astrophysics Data System (ADS)

    Pance, Gordana; Wengler, Micheal J.

    1994-04-01

    A broadband quasi-optical superconducting tunnel junction (SIS) mixer with integrated tuning elements was designed and tested. We are able to achieve very low noise performance using commercially available niobium integrated circuit (IC) technology. The low critical current density (980 A/sq cm) and large area (12 sq micron) of the commercial SIS's is compensated by the ability to fabricate accurate integrated tuning structures in the mature niobium IC process available from Hypres, Inc. Noise measurements were made in the frequency range from 70 to 105 GHz. The best uncorrected double sideband receiver noise is 38 K at 77 GHz, with receiver noise temperatures less than 100 K from 75 to 102 GHz.

  13. Large-area multilayer infrared nano-wire grid polarizers

    NASA Astrophysics Data System (ADS)

    Gayduk, Alexey E.; Prinz, Victor Ya.; Seleznev, Vladimir A.; Rechkunov, Sergey N.

    2016-03-01

    We have developed a technology for fabricating infrared polarizers based on double- and four-layer metal-dielectric nanogratings. Due to the use of nanoimprint lithography, the size of fabricated samples with 190-nm grating period could be made exceeding 170 cm2. The fabricated polarizers are flexible, and they have high quality over the entire area of the sample. Spectrophotometric measurements and numerical simulations have showed that the polarizers exhibited a large transmission coefficient and a high extinction ratio (over 3 ṡ 104). In order to expand applications of polarizers to the bio-inspired wide field-of-view systems, technology for fabricating polarizers on curved surfaces prepared by 3D printing has been developed. The obtained results offer much promise for polarimetry purposes.

  14. Plasma generating apparatus for large area plasma processing

    DOEpatents

    Tsai, C.C.; Gorbatkin, S.M.; Berry, L.A.

    1991-07-16

    A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm[sup 2]. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity. 3 figures.

  15. Plasma generating apparatus for large area plasma processing

    DOEpatents

    Tsai, Chin-Chi; Gorbatkin, Steven M.; Berry, Lee A.

    1991-01-01

    A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm.sup.2. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity.

  16. A complex plasma device of large surface area

    SciTech Connect

    Nakamura, Y.; Ishihara, O.

    2008-03-15

    A novel complex plasma device (YCOPEX) to create two-dimensional monolayer plasma crystals of a large surface area of 15x90 cm{sup 2} is described. The YCOPEX, in which a plasma is produced by a rf discharge of argon gas, is designed to utilize gravitational force to study fundamental physics of complex plasmas. The device may be used for observation of spatial change of a phase state, propagation of waves, and collisions of flowing dust particles with an obstacle. As an example of experiments, neutral drag forces on microspheres are measured using the gravitational force on those particles. The obtained neutral drag force agrees reasonably with the values estimated from Epstein's formula.

  17. Large area high efficiency multicrystalline silicon solar cell

    NASA Astrophysics Data System (ADS)

    Shirasawa, Katsuhiko; Yamashita, Hironori; Fukui, Kenji; Takayama, Michihiro; Okada, Kenichi

    A high-efficiency, low-cost large-area multicrystalline silicon solar cell having a cell size of 15 cm x 15 cm and a substrate made by the casting method has been developed. The bifacial silicon nitride solar cell (BSNSC) fabrication process was used to construct the cell. By incorporating a new structure at the cell surface, an optimized back-surface field (BSF) process, and an electrode with a ratio of 5.2 percent into the BSNSC fabrication process, a conversion efficiency of 15.1 percent (global, AM1.5, 100 mW/sq cm, 25 C) has been obtained. The uniformity of the electrical performance of the cell has been studied by measuring the distribution of the spectral response at various points on the cell. The results of uniformity testing are presented.

  18. PROSPECTS FOR GRB SCIENCE WITH THE FERMI LARGE AREA TELESCOPE

    SciTech Connect

    Band, D. L.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Battelino, M.; Bissaldi, E.; Bogaert, G.; Chiang, J.; Do Couto e Silva, E.; Cohen-Tanugi, J.; Cutini, S.; De Palma, F.; Dingus, B. L.; Fishman, G.

    2009-08-20

    The Large Area Telescope (LAT) instrument on the Fermi mission will reveal the rich spectral and temporal gamma-ray burst (GRB) phenomena in the >100 MeV band. The synergy with Fermi's Gamma-ray Burst Monitor detectors will link these observations to those in the well explored 10-1000 keV range; the addition of the >100 MeV band observations will resolve theoretical uncertainties about burst emission in both the prompt and afterglow phases. Trigger algorithms will be applied to the LAT data both onboard the spacecraft and on the ground. The sensitivity of these triggers will differ because of the available computing resources onboard and on the ground. Here we present the LAT's burst detection methodologies and the instrument's GRB capabilities.

  19. Large Area Printing of 3D Photonic Crystals

    NASA Astrophysics Data System (ADS)

    Watkins, James J.; Beaulieu, Michael R.; Hendricks, Nicholas R.; Kothari, Rohit

    2014-03-01

    We have developed a readily scalable print, lift, and stack approach for producing large area, 3D photonic crystal (PC) structures. UV-assisted nanoimprint lithography (UV-NIL) was used to pattern grating structures comprised of highly filled nanoparticle polymer composite resists with tune-able refractive indices (RI). The gratings were robust and upon release from a support substrate were oriented and stacked to yield 3D PCs. The RI of the composite resists was tuned between 1.58 and 1.92 at 800 nm while maintaining excellent optical transparency. The grating structure dimensions, line width, depth, and pitch, were easily varied by simply changing the imprint mold. For example, a 6 layer log-pile stack was prepared using a composite resist a RI of 1.72 yielding 72 % reflection at 900 nm. The process is scalable for roll-to-roll (R2R) production. Center for Hierarchical Manufacturing - an NSF Nanoscale Science and Engineering Center.

  20. The calorimeter of the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Grove, J. Eric; Johnson, W. Neil

    2010-07-01

    The Large Area Telescope (LAT), the primary instrument on the Fermi Gamma-ray Space Telescope, has been making revolutionary observations of the high-energy (20 MeV - 300 GeV) gamma-ray sky since its launch in June 2008. The LAT calorimeter is a modular array of 1536 CsI(Tl) crystals supported within 16 carbon fiber structures and read out at each crystal end with silicon PIN photodiodes to provide both energy and position information. The hodoscopic crystal stack allows imaging of electromagnetic showers and cosmic rays for improved energy measurement and background rejection. Signals from the array of photodiodes are processed by custom ASICs and commercial ADCs. We describe the calorimeter design and the primary factors that led those design choices.

  1. Noise-Immune Conjugate Large-Area Atom Interferometers

    SciTech Connect

    Chiow Shengwey; Herrmann, Sven; Chu, Steven; Mueller, Holger

    2009-07-31

    We present a pair of simultaneous conjugate Ramsey-Borde atom interferometers using large (20(Planck constant/2pi)k)-momentum transfer beam splitters, where (Planck constant/2pi)k is the photon momentum. Simultaneous operation allows for common-mode rejection of vibrational noise. This allows us to surpass the enclosed space-time area of previous interferometers with a splitting of 20(Planck constant/2pi)k by a factor of 2500. Using a splitting of 10(Planck constant/2pi)k, we demonstrate a 3.4 ppb resolution in the measurement of the fine structure constant. Examples for applications in tests of fundamental laws of physics are given.

  2. Large-area wide-angle spectrally selective plasmonic absorber

    NASA Astrophysics Data System (ADS)

    Wu, Chihhui; Neuner, Burton, III; Shvets, Gennady; John, Jeremy; Milder, Andrew; Zollars, Byron; Savoy, Steve

    2011-08-01

    A simple metamaterial-based wide-angle plasmonic absorber is introduced, fabricated, and experimentally characterized using angle-resolved infrared spectroscopy. The metamaterials are prepared by nano-imprint lithography, an attractive low-cost technology for making large-area samples. The matching of the metamaterial’s impedance to that of vacuum is responsible for the observed spectrally selective “perfect” absorption of infrared light. The impedance is theoretically calculated in the single-resonance approximation, and the responsible resonance is identified as a short-range surface plasmon. The spectral position of the absorption peak (which is as high as 95%) is experimentally shown to be controlled by the metamaterial’s dimensions. The persistence of “perfect” absorption with variable metamaterial parameters is theoretically explained. The wide-angle nature of the absorber can be utilized for subdiffraction-scale infrared pixels exhibiting spectrally selective absorption/emissivity.

  3. Optical Distortion Evaluation in Large Area Windows using Interferometry

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C.; Skow, Miles; Nurge, Mark A.

    2015-01-01

    It is important that imagery seen through large area windows, such as those used on space vehicles, not be substantially distorted. Many approaches are described in the literature for measuring the distortion of an optical window, but most suffer from either poor resolution or processing difficulties. In this paper a new definition of distortion is presented, allowing accurate measurement using an optical interferometer. This new definition is shown to be equivalent to the definitions provided by the military and the standards organizations. In order to determine the advantages and disadvantages of this new approach the distortion of an acrylic window is measured using three different methods; image comparison, Moiré interferometry, and phase-shifting interferometry.

  4. Study on the sensing performance of OFBG under large-scale negative strain

    NASA Astrophysics Data System (ADS)

    Wang, Chuan; Hu, Qingli; Ou, Jinping

    2010-03-01

    As a new and sensitive sensing element, OFBG(Optical Fiber Bragg Grating) has been widely used in aerospace engineering and civil engineering. The sensing mechanism and properties have been widely studied by lots of researchers, but the sensing properties of OFBG under large negative strain are still destitute. In this paper, with the aids of large shrinkage performance of PP(polypropylene) during its curing, we gained about -13000 μɛ's strain changes by embeding bare OFBG inside the PP bar to study the sensing properties of OFBG in this strain level. The results show that OFBG can remain its sensing properties well---- linearity, repeatability and the shape of centre wavelength are both reasonably. And the strain sensitivity coefficient of PP-OFBG is about 0.85 pm/μɛ, this is very near with that of calculating results considering strain transmission between PP and OFBG. Which are all helpful and useful for further use of OFBG in other applications.

  5. A new approach for defect inspection on large area masks

    NASA Astrophysics Data System (ADS)

    Scheuring, Gerd; Döbereiner, Stefan; Hillmann, Frank; Falk, Günther; Brück, Hans-Jürgen

    2007-02-01

    Besides the mask market for IC manufacturing, which mainly uses 6 inch sized masks, the market for the so called large area masks is growing very rapidly. Typical applications of these masks are mainly wafer bumping for current packaging processes, color filters on TFTs, and Flip Chip manufacturing. To expose e.g. bumps and similar features on 200 mm wafers under proximity exposure conditions 9 inch masks are used, while in 300 mm wafer bumping processes (Fig. 1) 14 inch masks are handled. Flip Chip manufacturing needs masks up to 28 by 32 inch. This current maximum mask dimension is expected to hold for the next 5 years in industrial production. On the other hand shrinking feature sizes, just as in case of the IC masks, demand enhanced sensitivity of the inspection tools. A defect inspection tool for those masks is valuable for both the mask maker, who has to deliver a defect free mask to his customer, and for the mask user to supervise the mask behavior conditions during its lifetime. This is necessary because large area masks are mainly used for proximity exposures. During this process itself the mask is vulnerable by contacting the resist on top of the wafers. Therefore a regular inspection of the mask after 25, 50, or 100 exposures has to be done during its whole lifetime. Thus critical resist contamination and other defects, which lead to yield losses, can be recognized early. In the future shrinking feature dimensions will require even more sensitive and reliable defect inspection methods than they do presently. Besides the sole inspection capability the tools should also provide highly precise measurement capabilities and extended review options.

  6. Background simulations for the Large Area Detector onboard LOFT

    NASA Astrophysics Data System (ADS)

    Campana, Riccardo; Feroci, Marco; Del Monte, Ettore; Mineo, Teresa; Lund, Niels; Fraser, George W.

    2013-12-01

    The Large Observatory For X-ray Timing (LOFT), currently in an assessment phase in the framework the ESA M3 Cosmic Vision programme, is an innovative medium-class mission specifically designed to answer fundamental questions about the behaviour of matter, in the very strong gravitational and magnetic fields around compact objects and in supranuclear density conditions. Having an effective area of ˜10 m2 at 8 keV, LOFT will be able to measure with high sensitivity very fast variability in the X-ray fluxes and spectra. A good knowledge of the in-orbit background environment is essential to assess the scientific performance of the mission and optimize the design of its main instrument, the Large Area Detector (LAD). In this paper the results of an extensive Geant-4 simulation of the instrumentwillbe discussed, showing the main contributions to the background and the design solutions for its reduction and control. Our results show that the current LOFT/LAD design is expected to meet its scientific requirement of a background rate equivalent to 10 mCrab in 2‒30 keV, achieving about 5 mCrab in the most important 2-10 keV energy band. Moreover, simulations show an anticipated modulation of the background rate as small as 10 % over the orbital timescale. The intrinsic photonic origin of the largest background component also allows for an efficient modelling, supported by an in-flight active monitoring, allowing to predict systematic residuals significantly better than the requirement of 1 %, and actually meeting the 0.25 % science goal.

  7. Negative Associations between Corpus Callosum Midsagittal Area and IQ in a Representative Sample of Healthy Children and Adolescents

    PubMed Central

    Ganjavi, Hooman; Lewis, John D.; Bellec, Pierre; MacDonald, Penny A.; Waber, Deborah P.; Evans, Alan C.; Karama, Sherif

    2011-01-01

    Documented associations between corpus callosum size and cognitive ability have heretofore been inconsistent potentially owing to differences in sample characteristics, differing methodologies in measuring CC size, or the use of absolute versus relative measures. We investigated the relationship between CC size and intelligence quotient (IQ) in the NIH MRI Study of Normal Brain Development sample, a large cohort of healthy children and adolescents (aged six to 18, n = 198) recruited to be representative of the US population. CC midsagittal area was measured using an automated system that partitioned the CC into 25 subregions. IQ was measured using the Wechsler Abbreviated Scale of Intelligence (WASI). After correcting for total brain volume and age, a significant negative correlation was found between total CC midsagittal area and IQ (r = −0.147; p = 0.040). Post hoc analyses revealed a significant negative correlation in children (age<12) (r = −0.279; p = 0.004) but not in adolescents (age≥12) (r = −0.005; p = 0.962). Partitioning the subjects by gender revealed a negative correlation in males (r = −0.231; p = 0.034) but not in females (r = 0.083; p = 0.389). Results suggest that the association between CC and intelligence is mostly driven by male children. In children, a significant gender difference was observed for FSIQ and PIQ, and in males, a significant age-group difference was observed for FSIQ and PIQ. These findings suggest that the correlation between CC midsagittal area and IQ may be related to age and gender. PMID:21625542

  8. Negative pressure wound therapy combined with skin grafting improves surgical wound healing in the perianal area.

    PubMed

    Jia-Zi, Shi; Xiao, Zhai; Jun-Hui, Li; Chun-Yu, Xue; Hong-da, Bi

    2016-08-01

    Management of large tissue defects resulting from local wide resection of perianal is a clinical challenge for surgeons. The aim of the present study was to investigate the efficacy of negative pressure wound therapy (NPWT) following skin grafting on perianal surgical wound healing.Included in this study were 12 patients with perianal tumors who received skin grafting after perianal tumor resection between December 2012 and December 2014. A self-designed negative pressure drainage device was then applied to maintain a standard negative pressure at -150 mm Hg and removed on day 8 postoperation. The outcome was recorded immediately after NPWT and at 6-month follow-up.All skin grafts survived without infection, hematoma, and necrosis in all 12 patients. No tumor recurrence was detected during 6-month follow-up. Natural folds were observed around the anus. All patients showed normal bowel movements.NPWT following skin grafting was effective for perianal surgical wound healing and infection prevention, thus benefiting anatomical and functional recovery of the anus. PMID:27583890

  9. Negative pressure wound therapy combined with skin grafting improves surgical wound healing in the perianal area

    PubMed Central

    Jia-zi, Shi; Xiao, Zhai; Jun-hui, Li; Chun-yu, Xue; Hong-da, Bi

    2016-01-01

    Abstract Management of large tissue defects resulting from local wide resection of perianal is a clinical challenge for surgeons. The aim of the present study was to investigate the efficacy of negative pressure wound therapy (NPWT) following skin grafting on perianal surgical wound healing. Included in this study were 12 patients with perianal tumors who received skin grafting after perianal tumor resection between December 2012 and December 2014. A self-designed negative pressure drainage device was then applied to maintain a standard negative pressure at −150 mm Hg and removed on day 8 postoperation. The outcome was recorded immediately after NPWT and at 6-month follow-up. All skin grafts survived without infection, hematoma, and necrosis in all 12 patients. No tumor recurrence was detected during 6-month follow-up. Natural folds were observed around the anus. All patients showed normal bowel movements. NPWT following skin grafting was effective for perianal surgical wound healing and infection prevention, thus benefiting anatomical and functional recovery of the anus. PMID:27583890

  10. A large area detector for x-ray applications

    SciTech Connect

    Rodricks, B.; Huang, Qiang; Hopf, R.; Wang, Kemei

    1993-10-01

    A large area detector for x-ray synchrotron applications has been developed. The front end of this device consist of a scintillator coupled to a fiber-optic taper. The fiber-optic taper is comprised of 4 smaller (70 mm x 70 mm) tapers fused together in a square matrix giving an active area of 140 mm x 140 mm. Each taper has a demagnification of 5.5 resulting in four small ends that are 12 mm diagonally across. The small ends of each taper are coupled to four microchannel-plate-based image intensifiers. The output from each image intensifier is focused onto a Charge Coupled Device (CCD) detector. The four CCDs are read out in parallel and are independently controlled. The image intensifiers also act as fast (20 ns) electronic shutters. The system is capable of displaying images in real time. Additionally, with independent control on the readout of each row of data from the CCD, the system is capable of performing high speed imaging through novel readout manipulation.

  11. Development of a large area space solar cell assembly

    NASA Technical Reports Server (NTRS)

    Spitzer, M. B.

    1982-01-01

    The development of a large area high efficiency solar cell assembly is described. The assembly consists of an ion implanted silicon solar cell and glass cover. The important attributes of fabrication are the use of a back surface field which is compatible with a back surface reflector, and integration of coverglass application and cell fabrications. Cell development experiments concerned optimization of ion implantation processing of 2 ohm-cm boron-doped silicon. Process parameters were selected based on these experiments and cells with area of 34.3 sq cm wre fabricated. The average AMO efficiency of the twenty-five best cells was 13.9% and the best bell had an efficiency of 14.4%. An important innovation in cell encapsulation was also developed. In this technique, the coverglass is applied before the cell is sawed to final size. The coverglass and cell are then sawed as a unit. In this way, the cost of the coverglass is reduced, since the tolerance on glass size is relaxed, and costly coverglass/cell alignment procedures are eliminated. Adhesive investigated were EVA, FEP-Teflon sheet and DC 93-500. Details of processing and results are reported.

  12. High-efficiency large-area CdTe modules

    NASA Astrophysics Data System (ADS)

    Albright, S. P.; Ackerman, B.

    1989-10-01

    A small solar cell with an efficiency of 12.3 percent was examined. The high efficiency of this device was largely due to improving the window layer. Analyzing the diode characteristics of this cell indicates that the largest potential for fill-factor improvement lies in reducing the diode quality factor. Through outdoor life testing of encapsulated modules and accelerated life testing of laboratory cells, the CdS/CdTe structure has demonstrated the long term stability necessary for photovoltaic products. Also described is a preformed metal backcap, which is fitted with hermetic feed-through tubes and used for encapsulization. Using the results of these studies, PEI produced sample modules with efficiencies very close to the original objectives, including a 1 sq ft module with an output of 6.1 W and an active area of 754 sq cm. For this module, the active area efficiency was 8.1 percent and the aperture efficiency was 7.3 percent.

  13. Large Area Nondestructive Evaluation of a Fatigue Loaded Composite Structure

    NASA Technical Reports Server (NTRS)

    Zalameda, Joseph N.; Burke, Eric R.; Horne, Michael R.; Madaras, Eric I.

    2016-01-01

    Large area nondestructive evaluation (NDE) inspections are required for fatigue testing of composite structures to track damage initiation and growth. Of particular interest is the progression of damage leading to ultimate failure to validate damage progression models. In this work, passive thermography and acoustic emission NDE were used to track damage growth up to failure of a composite three-stringer panel. Fourteen acoustic emission sensors were placed on the composite panel. The signals from the array were acquired simultaneously and allowed for acoustic emission location. In addition, real time thermal data of the composite structure were acquired during loading. Details are presented on the mapping of the acoustic emission locations directly onto the thermal imagery to confirm areas of damage growth leading to ultimate failure. This required synchronizing the acoustic emission and thermal data with the applied loading. In addition, processing of the thermal imagery which included contrast enhancement, removal of optical barrel distortion and correction of angular rotation before mapping the acoustic event locations are discussed.

  14. Edge field emission of large-area single layer graphene

    NASA Astrophysics Data System (ADS)

    Kleshch, Victor I.; Bandurin, Denis A.; Orekhov, Anton S.; Purcell, Stephen T.; Obraztsov, Alexander N.

    2015-12-01

    Field electron emission from the edges of large-area (∼1 cm × 1 cm) graphene films deposited onto quartz wafers was studied. The graphene was previously grown by chemical vapour deposition on copper. An extreme enhancement of electrostatic field at the edge of the films with macroscopically large lateral dimensions and with single atom thickness was achieved. This resulted in the creation of a blade type electron emitter, providing stable field emission at low-voltage with linear current density up to 0.5 mA/cm. A strong hysteresis in current-voltage characteristics and a step-like increase of the emission current during voltage ramp up were observed. These effects were explained by the local mechanical peeling of the graphene edge from the quartz substrate by the ponderomotive force during the field emission process. Specific field emission phenomena exhibited in the experimental study are explained by a unique combination of structural, electronic and mechanical properties of graphene. Various potential applications ranging from linear electron beam sources to microelectromechanical systems are discussed.

  15. Ultra-stiff large-area carpets of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Meysami, Seyyed Shayan; Dallas, Panagiotis; Britton, Jude; Lozano, Juan G.; Murdock, Adrian T.; Ferraro, Claudio; Gutierrez, Eduardo Saiz; Rijnveld, Niek; Holdway, Philip; Porfyrakis, Kyriakos; Grobert, Nicole

    2016-06-01

    Herewith, we report the influence of post-synthesis heat treatment (<=2350 °C and plasma temperatures) on the crystal structure, defect density, purity, alignment and dispersibility of free-standing large-area (several cm2) carpets of ultra-long (several mm) vertically aligned multi-wall carbon nanotubes (VA-MWCNTs). VA-MWCNTs were produced in large quantities (20-30 g per batch) using a semi-scaled-up aerosol-assisted chemical vapour deposition (AACVD) setup. Electron and X-ray diffraction showed that the heat treatment at 2350 °C under inert atmosphere purifies, removes residual catalyst particles, and partially aligns adjacent single crystals (crystallites) in polycrystalline MWCNTs. The purification and improvement in the crystallites alignment within the MWCNTs resulted in reduced dispersibility of the VA-MWCNTs in liquid media. High-resolution microscopy revealed that the crystallinity is improved in scales of few tens of nanometres while the point defects remain largely unaffected. The heat treatment also had a marked benefit on the mechanical properties of the carpets. For the first time, we report compression moduli as high as 120 MPa for VA-MWCNT carpets, i.e. an order of magnitude higher than previously reported figures. The application of higher temperatures (arc-discharge plasma, >=4000 °C) resulted in the formation of a novel graphite-matrix composite reinforced with CVD and arc-discharge-like carbon nanotubes.Herewith, we report the influence of post-synthesis heat treatment (<=2350 °C and plasma temperatures) on the crystal structure, defect density, purity, alignment and dispersibility of free-standing large-area (several cm2) carpets of ultra-long (several mm) vertically aligned multi-wall carbon nanotubes (VA-MWCNTs). VA-MWCNTs were produced in large quantities (20-30 g per batch) using a semi-scaled-up aerosol-assisted chemical vapour deposition (AACVD) setup. Electron and X-ray diffraction showed that the heat treatment at 2350 °C under

  16. Low-Field, Large-Area Helicon Sources

    NASA Astrophysics Data System (ADS)

    Chen, F. F.; Evans, J. D.; Jiang, X.; Tynan, G.

    1996-10-01

    Previous experiments footnote F.F. Chen and G. Chevalier, J. Vac. Sci. Technol. A 10, 1389 (1992). with helicon discharges in both 1- and 2-inch diam tubes have shown a density peak at magnetic fields B between 10 and 40 G and that this peak appears only with RF powers >1kW. Theory indicates that the Trivelpiece-Gould branch of the dispersion relation is important at low B, but it is not clear whether the density rise is due to increased absorption or simply to impurities from the wall. Multiple discharges of this type can be used to create a large-area plasma source for industrial applications. Two devices have been constructed to test this idea. Device 1 has a 2-in diam tube, 6-in long, with a right-hand helical antenna and a 0-100 G field, injecting plasma into a large B = 0 region. RF power at 13.56 and 27.12 MHz is applied up to 600W. The plasma density falls off with increasing B-field and is highest at 0 G. With a 12-in long tube, this fall-off is eliminate! d.! De vice 2 has 7 tubes of the same type arranged in a honeycomb pattern on the top plate of a large chamber with multi-dipole confinement. By careful matching, discharges can be struck in all 7 tubes simultaneously. Density uniformity data is not available at the time of this abstract. These devices unfortunately cannot be used to verify the theory, since the magnetic fields are nonuniform.

  17. MONITORING OF LARGE INSTABLE AREAS: system reliability and new tools.

    NASA Astrophysics Data System (ADS)

    Leandro, G.; Mucciarelli, M.; Pellicani, R.; Spilotro, G.

    2009-04-01

    The monitoring of unstable or potentially unstable areas is a necessary operation every time you can not remove the conditions of risk and apply to mitigation measures. In Italian Apennine regions there are many urban or extra-urban areas affected by instability, for which it is impracticable to remove hazard conditions, because of size and cost problems. The technological evolution exportable to the field of land instability monitoring is particularly lively and allows the use of warning systems unthinkable just few years ago. However, the monitoring of unstable or potentially unstable areas requires a very great knowledge of the specific problems, without which the reliability of the system may be dangerously overestimated. The movement may arise, indeed, in areas not covered by instrumentation, or covered with vegetation that prevents the acquisition of both reflected signals in the multi-beam laser techniques and radar signals. Environmental conditions (wind, concentrated sources of light, temperature changes, presence of animals) may also invalidate the accuracy of the measures, by introducing modulations or disturbance at a level well above the threshold of alarm signal, leading consequently to raise the values of the warning threshold. The Authors have gained long experience with the observation and monitoring of some large landslides in the Southern Apennine (Aliano, Buoninventre, Calciano, Carlantino, etc.) and unstable areas also at regional scale. One of the most important experiences is about the case of landslides of extensive areas, where unstable and stables zones coexist along transverse and longitudinal axis. In many of these cases you need the accurate control of the movement at selected points to evaluate the trend of displacement velocity, which can be achieved by means of a single-beam laser. The control of these movements, however, does not provide information on stress pattern into the stable areas. Among the sensitive precursors, acoustic

  18. Characteristics of long-pulse negative-ion source in the neutral beam injector of Large Helical Device

    NASA Astrophysics Data System (ADS)

    Takeiri, Y.; Ikeda, K.; Oka, Y.; Tsumori, K.; Osakabe, M.; Nagaoka, K.; Kaneko, O.; Asano, E.; Kondo, T.; Sato, M.; Shibuya, M.; Komada, S.

    2006-03-01

    The injection duration has been extended beyond 100 s with a high-power hydrogen negative-ion source in a negative-ion-based neutral beam injector of the Large Helical Device superconducting fusion machine. The ion source is a cesium-seeded source with a thermally insulated plasma grid (PG), and optimized for a short-pulse operation of 2-3 s. The negative-ion production efficiency is strongly dependent on the PG temperature, and in the long-pulse operation it exceeds an appropriate temperature range of 200-300 °C, at which the optimum cesium coverage is formed on the PG surface. By making the PG temperature rise slower with a reduced arc power, the injection duration was extended to 110 s with an injection power of 110 kW. To extend the injection duration further with a higher injection power, stainless-steel cooling tubes have been mechanically attached to the PG for suppression of the PG temperature rise in the long-pulse operation. As a result, a long-pulse injection with an injection power of 200 kW was extended to 128 s until it was manually stopped due to the plasma collapse. However, the beam duration could be limited to around 3 min because the PG temperature rise was not saturated due to a low thermal conductivity with the thickness of the stainless-steel tube determined so that the short-pulse operation is also possible. On the other hand, the longitudinal beam distribution in a grid area of 25×125cm2 is observed to be more uniform than that with the uncooled PG. The temperature distribution of the individual grid parts becomes more uniform with the cooled PG, which should contribute to the improvement of the beam uniformity.

  19. Building ISOC Status Displays for the Large AreaTelescope aboard the Gamma Ray Large Area Space Telescope (GLAST) Observatory

    SciTech Connect

    Ketchum, Christina; /SLAC

    2006-09-01

    In September 2007 the Gamma Ray Large Area Space Telescope (GLAST) is scheduled to launch aboard a Delta II rocket in order to put two high-energy gamma-ray detectors, the Large Area Telescope (LAT) and the GLAST Burst Monitor (GBM) into low earth orbit. The Instrument Science Operations Center (ISOC) at SLAC is responsible for the LAT operations for the duration of the mission, and will therefore build an operations center including a monitoring station at SLAC to inform operations staff and visitors of the status of the LAT instrument and GLAST. This monitoring station is to include sky maps showing the location of GLAST in its orbit as well as the LAT's projected field of view on the sky containing known gamma-ray sources. The display also requires a world map showing the locations of GLAST and three Tracking and Data Relay Satellites (TDRS) relative to the ground, their trail lines, and ''footprint'' circles indicating the range of communications for each satellite. The final display will also include a space view showing the orbiting and pointing information of GLAST and the TDRS satellites. In order to build the displays the astronomy programs Xephem, DS9, SatTrack, and STK were employed to model the position of GLAST and pointing information of the LAT instrument, and the programming utilities Python and Cron were used in Unix to obtain updated information from database and load them into the programs at regular intervals. Through these methods the indicated displays were created and combined to produce a monitoring display for the LAT and GLAST.

  20. Large area mode field photonic crystal fiber design

    NASA Astrophysics Data System (ADS)

    Guo, Shuqin; An, Wensheng; Wang, Kang; Zhu, Guangxin; Le, Zichun

    2005-11-01

    A novel design method about photonic crystal fiber (PCF) with large area model field (LAMF) is demonstrated. Different from ordinarily design that the core of PCF formed by missing one air holes in the center of section, many air holes distributed in heartland all together come into being the core region. Air holes are arranged regularly in core region and outer cladding regions according to different periodical character, respectively. The effective refractive index (n eff ) of core region should be higher than cladding region because of total internal reflection (TIR) requirement. In this paper, two kinds of typical scheme are offered to realize LAMF-PCF. First, Λ, the spacing of neighboring air holes in whole section is fixed, once the radius of air holes in the core region r c is smaller than the cladding air holes r cla, LAMF-PCF will be formed. The modal area only lessens a little as r c is reduced. Especially, optimal size of r c can nearly make MFA insensitive to wavelength. On the contrary, dispersion parameter of PCF will take place visible change along with r c reduced, and ultra-flattened dispersion character can be realized when r c is optimized. Another method of designing LAMF-PCF is keeping all air holes uniform in the whole section of PCF, but the space of neighboring air holes in the core region Λ c is longer than the cladding region Λ cla, so n eff of core region is higher than the cladding region and TIR can take place.

  1. DESIGN OF A LARGE-AREA FAST NEUTRON DIRECTIONAL DETECTOR.

    SciTech Connect

    VANIER, P.E.

    2006-10-29

    A large-area fast-neutron double-scatter directional detector and spectrometer is being constructed using l-meter-long plastic scintillator paddles with photomultiplier tubes at both ends. The scintillators detect fast neutrons by proton recoil and also gamma rays by Compton scattering. The paddles are arranged in two parallel planes so that neutrons can be distinguished from muons and gamma rays by time of flight between the planes. The signal pulses are digitized with a time resolution of one gigasample per second. The location of an event along each paddle can be determined from the relative amplitudes or timing of the signals at the ends. The angle of deflection of a neutron in the first plane can be estimated from the energy deposited by the recoil proton, combined with the scattered neutron time-of-flight energy. Each scattering angle can be back-projected as a cone, and many intersecting cones define the incident neutron direction from a distant point source. Moreover, the total energy of each neutron can be obtained, allowing some regions of a fission source spectrum to be distinguished from background generated by cosmic rays. Monte Carlo calculations will be compared with measurements.

  2. Large-area nanogap plasmon resonator arrays for plasmonics applications

    NASA Astrophysics Data System (ADS)

    Jin, Mingliang; van Wolferen, Henk; Wormeester, Herbert; van den Berg, Albert; Carlen, Edwin T.

    2012-07-01

    Large-area (~8000 mm2) Au nanogap plasmon resonator array substrates manufactured using maskless laser interference lithography (LIL) with high uniformity are presented. The periodically spaced subwavelength nanogap arrays are formed between adjacent nanopyramid (NPy) structures with precisely defined pitch and high length density (~1 km cm-2), and are ideally suited as scattering sites for surface enhanced Raman scattering (SERS), as well as refractive index sensing. The two-dimensional grid arrangement of NPy structures renders the excitation of the plasmon resonators minimally dependent on the incident polarization. The SERS average enhancement factor (AEF) has been characterized using over 30 000 individual measurements of benzenethiol (BT) chemisorbed on the Au NPy surfaces. From the 1(a1), βCCC + νCS ring mode (1074 cm-1) of BT on surfaces with pitch λg = 200 nm, AEF = 0.8 × 106 and for surfaces with λg = 500 nm, AEF = 0.3 × 107 from over 99% of the imaged spots. Maximum AEFs > 108 have been measured in both cases.

  3. Research and Development of Large Area Color AC Plasma Displays

    NASA Astrophysics Data System (ADS)

    Shinoda, Tsutae

    1998-10-01

    Plasma display is essentially a gas discharge device using discharges in small cavities about 0. 1 m. The color plasma displays utilize the visible light from phosphors excited by the ultra-violet by discharge in contrast to monochrome plasma displays utilizing visible light directly from gas discharges. At the early stage of the color plasma display development, the degradation of the phosphors and unstable operating voltage prevented to realize a practical color plasma display. The introduction of the three-electrode surface-discharge technology opened the way to solve the problems. Two key technologies of a simple panel structure with a stripe rib and phosphor alignment and a full color image driving method with an address-and-display-period-separated sub-field method have realized practically available full color plasma displays. A full color plasma display has been firstly developed in 1992 with a 21-in.-diagonal PDP and then a 42-in.-diagonal PDP in 1995 Currently a 50-in.-diagonal color plasma display has been developed. The large area color plasma displays have already been put into the market and are creating new markets, such as a wall hanging TV and multimedia displays for advertisement, information, etc. This paper will show the history of the surface-discharge color plasma display technologies and current status of the color plasma display.

  4. Pulsar Simulations for the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Razzano, M.; Harding, A. K.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Burnett, T.; Chiang, J.; Digel, S. W.; Dubois, R.; Kuss, M. W.; Latronico, L.; McEnery, J. E.; Omodei, N.; Pesce-Rollins, M.; Sgro, C.; Spandre, G.; Thompson, D. J.

    2009-01-01

    Pulsars are among the prime targets for the Large Area Telescope (LAT) aboard the recently launched Fermi observatory. The LAT will study the gamma-ray Universe between 20 MeV and 300 GeV with unprecedented detail. Increasing numbers of gamma-ray pulsars are being firmly identified, yet their emission mechanisms are far from being understood. To better investigate and exploit the tAT capabilities for pulsar science. a set of new detailed pulsar simulation tools have been developed within the LAT collaboration. The structure of the pulsar simulator package (PulsarSpeccrum) is presented here. Starting from photon distributions in energy and phase obtained from theoretical calculations or phenomenological considerations, gamma-rays are generated and their arrival times at the spacecraft are determined by taking Into account effects such as barycentric effects and timing noise. Pulsars in binary systems also can be simulated given orbital parameters. We present how simulations can be used for generating a realistic set of gamma rays as observed by the LAT, focusing on some case studies that show the performance of the LAT for pulsar observations.

  5. Fermi Large Area Telescope Operations: Progress Over 4 Years

    SciTech Connect

    Cameron, Robert A.; /SLAC

    2012-06-28

    The Fermi Gamma-ray Space Telescope was launched into orbit in June 2008, and is conducting a multi-year gamma-ray all-sky survey, using the main instrument on Fermi, the Large Area Telescope (LAT). Fermi began its science mission in August 2008, and has now been operating for almost 4 years. The SLAC National Accelerator Laboratory hosts the LAT Instrument Science Operations Center (ISOC), which supports the operation of the LAT in conjunction with the Mission Operations Center (MOC) and the Fermi Science Support Center (FSSC), both at NASA's Goddard Space Flight Center. The LAT has a continuous output data rate of about 1.5 Mbits per second, and data from the LAT are stored on Fermi and transmitted to the ground through TDRS and the MOC to the ISOC about 10 times per day. Several hundred computers at SLAC are used to process LAT data to perform event reconstruction, and gamma-ray photon data are subsequently delivered to the FSSC for public release with a few hours of being detected by the LAT. We summarize the current status of the LAT, and the evolution of the data processing and monitoring performed by the ISOC during the first 4 years of the Fermi mission, together with future plans for further changes to detected event data processing and instrument operations and monitoring.

  6. FERMI LARGE AREA TELESCOPE DETECTION OF SUPERNOVA REMNANT RCW 86

    SciTech Connect

    Yuan, Qiang; Huang, Xiaoyuan; Liu, Siming; Zhang, Bing

    2014-04-20

    Using 5.4 yr Fermi Large Area Telescope data, we report the detection of GeV γ-ray emission from the shell-type supernova remnant RCW 86 (G315.4-2.3) with a significance of ∼5.1σ. The data slightly favors an extended emission of this supernova remnant. The spectral index of RCW 86 is found to be very hard, Γ ∼ 1.4, in the 0.4-300 GeV range. A one-zone leptonic model can well fit the multi-wavelength data from radio to very high energy γ-rays. The very hard GeV γ-ray spectrum and the inferred low gas density seem to disfavor a hadronic origin for the γ-rays. The γ-ray behavior of RCW 86 is very similar to several other TeV shell-type supernova remnants, e.g., RX J1713.7-3946, RX J0852.0-4622, SN 1006, and HESS J1731-347.

  7. The new event analysis of the Fermi large area telescope

    NASA Astrophysics Data System (ADS)

    Sgrò, Carmelo

    2014-07-01

    Since its launch on June 11, 2008 the Fermi Large Area Telescope (LAT) has been exploring the gamma-ray sky at energies from 20 MeV to over 300 GeV. Five years of nearly flawless operation allowed a constant improvement of the detector knowledge and, as a consequence, continuous update of the event selection and the corresponding instrument response parametrization. The final product of this effort is a radical revision of the entire event-level analysis, from the event reconstruction algorithms in each subsystem to the background rejection strategy. The potential improvements include a larger acceptance coupled with a significant reduction in background contamination, better angular and energy resolution and an extension of the energy reach below 100 MeV and in the TeV range. In this paper I will describe the new reconstruction and the event-level analysis, show the expected instrument performance and discuss future prospects for astro-particle physics with the LAT.

  8. Flexible and mechanical strain resistant large area SERS active substrates

    NASA Astrophysics Data System (ADS)

    Singh, J. P.; Chu, Hsiaoyun; Abell, Justin; Tripp, Ralph A.; Zhao, Yiping

    2012-05-01

    We report a cost effective and facile way to synthesize flexible, uniform, and large area surface enhanced Raman scattering (SERS) substrates using an oblique angle deposition (OAD) technique. The flexible SERS substrates consist of 1 μm long, tilted silver nanocolumnar films deposited on flexible polydimethylsiloxane (PDMS) and polyethylene terephthalate (PET) sheets using OAD. The SERS enhancement activity of these flexible substrates was determined using 10-5 M trans-1,2-bis(4-pyridyl) ethylene (BPE) Raman probe molecules. The in situ SERS measurements on these flexible substrates under mechanical (tensile/bending) strain conditions were performed. Our results show that flexible SERS substrates can withstand a tensile strain (ε) value as high as 30% without losing SERS performance, whereas the similar bending strain decreases the SERS performance by about 13%. A cyclic tensile loading test on flexible PDMS SERS substrates at a pre-specified tensile strain (ε) value of 10% shows that the SERS intensity remains almost constant for more than 100 cycles. These disposable and flexible SERS substrates can be integrated with biological substances and offer a novel and practical method to facilitate biosensing applications.

  9. Saturn: A large area x-ray simulation accelerator

    SciTech Connect

    Bloomquist, D.D.; Stinnett, R.W.; McDaniel, D.H.; Lee, J.R.; Sharpe, A.W.; Halbleib, J.A.; Schlitt, L.G.; Spence, P.W.; Corcoran, P.

    1987-01-01

    Saturn is the result of a major metamorphosis of the Particle Beam Fusion Accelerator-I (PBFA-I) from an ICF research facility to the large-area x-ray source of the Simulation Technology Laboratory (STL) project. Renamed Saturn, for its unique multiple-ring diode design, the facility is designed to take advantage of the numerous advances in pulsed power technology made by the ICF program in recent years and much of the existing PBFA-I support system. Saturn will include significant upgrades in the energy storage and pulse-forming sections. The 36 magnetically insulated transmission lines (MITLs) that provided power flow to the ion diode of PBFA-I were replaced by a system of vertical triplate water transmission lines. These lines are connected to three horizontal triplate disks in a water convolute section. Power will flow through an insulator stack into radial MITLs that drive the three-ring diode. Saturn is designed to operate with a maximum of 750 kJ coupled to the three-ring e-beam diode with a peak power of 25 TW to provide an x-ray exposure capability of 5 x 10/sup 12/ rads/s (Si) and 5 cal/g (Au) over 500 cm/sup 2/.

  10. Influence of the Earth's magnetic field on large area photomultipliers

    SciTech Connect

    Leonora, E.; Aiello, S.; Leotta, G.

    2011-07-01

    The influence of the Earth's magnetic field on large area photomultipliers proposed for a future deep sea neutrino telescope was studied under the EU-funded KM3NeT design study. The aims were to evaluate variations in PMT performance in the Earth's magnetic field and to decide whether the use of magnetic shielding is necessary. Measurements were performed on three Hamamatsu PMTs: two 8-inch R5912 types, one of these with super-bi-alkali photocathode, and a 10-inch R7081 type with a standard bi-alkali photocathode. The various characteristics of the PMTs were measured while varying the PMT orientations with respect to the Earth's magnetic field, both with and without a mu-metal cage as magnetic shield. In the 8-inch PMTs the impact of the magnetic field was found to be smaller than that on the 10-inch PMT. The increased quantum efficiency in the 8 super-bi-alkali PMT almost compensated its smaller detection surface compared to the 10' PMT. No significant effects were measured upon transit time and the fraction of spurious pulses. (authors)

  11. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE VELA PULSAR

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Bartelt, J.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bogart, J. R.; Atwood, W. B.; Bagagli, R.; Baldini, L.; Bellardi, F.; Bellazzini, R.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bisello, D.; Baughman, B. M. E-mail: massimiliano.razzano@pi.infn.it

    2009-05-10

    The Vela pulsar is the brightest persistent source in the GeV sky and thus is the traditional first target for new {gamma}-ray observatories. We report here on initial Fermi Large Area Telescope observations during verification phase pointed exposure and early sky survey scanning. We have used the Vela signal to verify Fermi timing and angular resolution. The high-quality pulse profile, with some 32,400 pulsed photons at E {>=} 0.03 GeV, shows new features, including pulse structure as fine as 0.3 ms and a distinct third peak, which shifts in phase with energy. We examine the high-energy behavior of the pulsed emission; initial spectra suggest a phase-averaged power-law index of {gamma} = 1.51{sup +0.05} {sub -0.04} with an exponential cutoff at E{sub c} = 2.9 {+-} 0.1 GeV. Spectral fits with generalized cutoffs of the form e{sup -(E/E{sub c}){sup b}} require b {<=} 1, which is inconsistent with magnetic pair attenuation, and thus favor outer-magnetosphere emission models. Finally, we report on upper limits to any unpulsed component, as might be associated with a surrounding pulsar wind nebula.

  12. Fabrication of large area nanostructures with surface modified silica spheres

    NASA Astrophysics Data System (ADS)

    Kang, Kwang-Sun

    2014-03-01

    Surface modification of silica spheres with 3-(trimethoxysilyl)propylmethacrylate (TMSPM) has been performed at ambient condition. However, the FTIR spectra and field emission scanning electron microscope (FESEM) images show no evidence of the surface modification. The reaction temperatures were varied from 60 to 80 °C with various reaction periods. Small absorption shoulder of the CO stretching vibration was at 1700 cm-1, and slightly increased with the increase of the reaction time at 60 °C. The clear absorption peak appeared at 1698 cm-1 for the spheres reacted for 80 min at 70 °C and shifted toward 1720 cm-1 with the increase the reaction time. Strong absorption peak showed at 1698 cm-1 and shifted toward 1725 cm-1 with the increase of the reaction time at 80 °C. The spheres were dispersed to methanol and added photoinitiator (Irgacure-184). The solution was poured to a patterned glass substrate and exposed to the 254 nm UV-light during a self-assembly process. A large area and crack-free silica sphere film was formed. To increase the mechanical stability, a cellulose acetate solution was spin-coated to the film. The film was lift-off from the glass substrate to analyze the surface nanostructures. The surface nanostructures were maintained, and the film is stable enough to use as a mold to duplicate the nanopattern and flexible.

  13. GLAST large area telescope - daily survey of high energy sky

    NASA Astrophysics Data System (ADS)

    Kamae, Tuneyoshi

    2003-07-01

    GLAST Large Area Telescope was proposed to NASA in 1999 as a follow-up of EGRET on-board Compton Gamma-Ray Observatory by an international collaboration. The proposal has been approved as a part of the GLAST observatory mission in its capability to explore a wide range of astrophysics with 5-40 times higher sensitivity and extended energy coverage (20MeV to 300GeV) than EGRET. The instrument consists of 16 towers of e+e- pair tracker, 16 blocks of segmented electro-magnetic calorimeter, and a set of anti-coicidence plastic scintillator tiles covering the tracker towers. It will have 5-10 times larger on-axis effective area, 6 times wider field-of-view (FOV), and up to 5 times better angular resolution when compared with EGRET. The Large Area Telescope will cover about 40% of the sky above the Earth's horizon in its FOV at any given time and will scan nearly the entire Universe every orbit (~ 90min): about 20% of Gamma-Ray Bursts will be observed from the onset of the bursts to the initial after-glow phase; all longer-lasting transients and variabilities will be detected daily at the improved sensitivity. The instrument has been prototyped twice between 1995 and 2001, designed almost to the Flight Model by the international collaboration of the US (NASA and DoE), France, Italy, Japan, and Sweden. The first prototype consisted of one tower of e+e- pair trackers, one block of segmented calorimeters and a smaller set of anti-coicidence plastic scintillator tiles (Beam Test Engineering Model, BTEM), which was put into e+, p, and γ beams at SLAC in the winter of 1999-2000. It was subsequently modified for a balloon experiment (Balloon Flight Engineering Model, BFEM) and flown at Palestine, Texas in August 2001. Data collected in the test experiments have been analyzed and compared with predictions of computer simulation codes such as Geant4. These studies have confirmed validity of the basic design, brought up a few issues for further improvement, and gathered data on

  14. Attribution and Characterisation of Sclerophyll Forested Landscapes Over Large Areas

    NASA Astrophysics Data System (ADS)

    Jones, Simon; Soto-Berelov, Mariela; Suarez, Lola; Wilkes, Phil; Woodgate, Will; Haywood, Andrew

    2016-06-01

    This paper presents a methodology for the attribution and characterisation of Sclerophyll forested landscapes over large areas. First we define a set of woody vegetation data primitives (e.g. canopy cover, leaf area index (LAI), bole density, canopy height), which are then scaled-up using multiple remote sensing data sources to characterise and extract landscape woody vegetation features. The advantage of this approach is that vegetation landscape features can be described from composites of these data primitives. The proposed data primitives act as building blocks for the re-creation of past woody characterisation schemes as well as allowing for re-compilation to support present and future policy and management and decision making needs. Three main research sites were attributed; representative of different sclerophyll woody vegetated systems (Box Iron-bark forest; Mountain Ash forest; Mixed Species foothills forest). High resolution hyperspectral and full waveform LiDAR data was acquired over the three research sites. At the same time, land management agencies (Victorian Department of Environment, Land Water and Planning) and researchers (RMIT, CRC for Spatial Information and CSIRO) conducted fieldwork to collect structural and functional measurements of vegetation, using traditional forest mensuration transects and plots, terrestrial lidar scanning and high temporal resolution in-situ autonomous laser (VegNet) scanners. Results are presented of: 1) inter-comparisons of LAI estimations made using ground based hemispherical photography, LAI 2200 PCA, CI-110 and terrestrial and airborne laser scanners; 2) canopy height and vertical canopy complexity derived from airborne LiDAR validated using ground observations; and, 3) time-series characterisation of land cover features. 1. Accuracy targets for remotely sensed LAI products to match within ground based estimates are ± 0.5 LAI or a 20% maximum (CEOS/GCOS) with new aspirational targets of 5%). In this research we

  15. Mapping regional patterns of large forest fires in Wildland-Urban Interface areas in Europe.

    PubMed

    Modugno, Sirio; Balzter, Heiko; Cole, Beth; Borrelli, Pasquale

    2016-05-01

    Over recent decades, Land Use and Cover Change (LUCC) trends in many regions of Europe have reconfigured the landscape structures around many urban areas. In these areas, the proximity to landscape elements with high forest fuels has increased the fire risk to people and property. These Wildland-Urban Interface areas (WUI) can be defined as landscapes where anthropogenic urban land use and forest fuel mass come into contact. Mapping their extent is needed to prioritize fire risk control and inform local forest fire risk management strategies. This study proposes a method to map the extent and spatial patterns of the European WUI areas at continental scale. Using the European map of WUI areas, the hypothesis is tested that the distance from the nearest WUI area is related to the forest fire probability. Statistical relationships between the distance from the nearest WUI area, and large forest fire incidents from satellite remote sensing were subsequently modelled by logistic regression analysis. The first European scale map of the WUI extent and locations is presented. Country-specific positive and negative relationships of large fires and the proximity to the nearest WUI area are found. A regional-scale analysis shows a strong influence of the WUI zones on large fires in parts of the Mediterranean regions. Results indicate that the probability of large burned surfaces increases with diminishing WUI distance in touristic regions like Sardinia, Provence-Alpes-Côte d'Azur, or in regions with a strong peri-urban component as Catalunya, Comunidad de Madrid, Comunidad Valenciana. For the above regions, probability curves of large burned surfaces show statistical relationships (ROC value > 0.5) inside a 5000 m buffer of the nearest WUI. Wise land management can provide a valuable ecosystem service of fire risk reduction that is currently not explicitly included in ecosystem service valuations. The results re-emphasise the importance of including this ecosystem service

  16. SPLASH: Spitzer Large Area Survey with Hyper-Suprime-Cam

    NASA Astrophysics Data System (ADS)

    Capak, Peter; Aussel, Herve; Bundy, Kevin; Carollo, Marcella; Ram-Chary, Ranga; Civano, Francesca; Coupon, Jean; Diener, Catrina; Donley, Jenifer; Dunlop, Jim; Elvis, Martin; Foucaud, Sebastien; Green, Jenny; Gunn, Jim; Hashimoto, Yasuhiro; Hassinger, Gunther; Hsieh, Bau-Ching; Huang, Lijin; Ilbert, Olivier; LeFloc'h, Emeric; LeFevre, Olivier; Lilly, Simon; Lin, Lihwai; Lin, Yen-Ting; Miyazaki, Satoshi; Mobasher, Bahram; Moriya, Takashi; Nagao, Tohru; Ono, Yoshiaki; Ouchi, Massami; Quimby, Robert; Saito, Tomoki; Salvato, Mara; Sanders, Dave; Schinnerer, Eva; Scoville, Nick; Shimasaku, Kazuhiro; Silverman, John; Smolcic, Vernesa; Strauss, Michael; Surace, Jason; Tanaka, Massayuki; Taniguchi, Yoshi; Teplitz, Harry; Wang, Wei-Hao; Urata, Yuji

    2012-09-01

    We propose a 2475h survey to build the foundation for comprehensive investigations of the earliest stages of galaxy, AGN and large-scale structure formation on cosmologically important scales, providing deep mid-IR imaging for two major 1.8deg^2 fields (COSMOS and SXDS). These two fields have been the target of, and are scheduled for, unparalleled deep imaging in the optical, sub-mm and radio. The Spitzer data is essential for immediate science goals and the legacy of these unique equatorial fields. The major science enabled by the proposed Spitzer observations includes: the co-evolution of cosmic large scale structure and the assembly and growth of galaxies and AGN; understanding the relative importance of smooth gas accretion vs. mergers for galaxy growth in the early universe; probing re-ionization through Infrared Background Fluctuations; constraining the Initial Mass Function at high redshift, AGN activity in the early universe, and the physics of supernova through transient studies. None of these are possible with existing Spitzer surveys, which are limited by both insufficient contiguous area, insufficient depth of ancillary data and/or temporal cadence. The two fields proposed here will have unique, Hyper-Suprime-Cam (HSC) imaging (to ~27-28 magAB for broad bands across the 0.4?1.0um wavelength range) and science will be immediately enabled by Spitzer using pre-existing deep X-ray to radio multi-wavelength data, including: UV (Galex), X-ray (Chandra/XMM), optical (HST), near-infrared, mid-Infrared (Spitzer/Herschel), sub-mm, and radio. The COSMOS field is the primary deep field for the Nu-Star mission and both fields have been ranked as high priority deep-field targets for Euclid. These fields also have extensive spectroscopy with Keck (>50nt), Subaru-FMOS (>30nt), VLT (>1000h), and are the primary targets for the future Subaru Prime Focus Spectrograph (PFS) surveys. The legacy impact of these data will be enormous, and will provide a treasure trove of

  17. Large-Area Permanent-Magnet ECR Plasma Source

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2007-01-01

    A 40-cm-diameter plasma device has been developed as a source of ions for material-processing and ion-thruster applications. Like the device described in the immediately preceding article, this device utilizes electron cyclotron resonance (ECR) excited by microwave power in a magnetic field to generate a plasma in an electrodeless (noncontact) manner and without need for an electrically insulating, microwave-transmissive window at the source. Hence, this device offers the same advantages of electrodeless, windowless design - low contamination and long operational life. The device generates a uniform, high-density plasma capable of sustaining uniform ion-current densities at its exit plane while operating at low pressure [<10(exp -4) torr (less than about 1.3 10(exp -2) Pa)] and input power <200 W at a frequency of 2.45 GHz. Though the prototype model operates at 2.45 GHz, operation at higher frequencies can be achieved by straightforward modification to the input microwave waveguide. Higher frequency operation may be desirable in those applications that require even higher background plasma densities. In the design of this ECR plasma source, there are no cumbersome, power-hungry electromagnets. The magnetic field in this device is generated by a permanent-magnet circuit that is optimized to generate resonance surfaces. The microwave power is injected on the centerline of the device. The resulting discharge plasma jumps into a "high mode" when the input power rises above 150 W. This mode is associated with elevated plasma density and high uniformity. The large area and uniformity of the plasma and the low operating pressure are well suited for such material-processing applications as etching and deposition on large silicon wafers. The high exit-plane ion-current density makes it possible to attain a high rate of etching or deposition. The plasma potential is <3 V low enough that there is little likelihood of sputtering, which, in plasma processing, is undesired

  18. A large area cooled-CCD detector for electron microscopy

    NASA Astrophysics Data System (ADS)

    Faruqi, A. R.; Andrews, H. N.; Raeburn, C.

    1994-09-01

    Large area cooled-CCDs are an excellent medium for (indirectly) recording electron images and electron diffraction patterns in real time and for use in electron tomography; real-time imaging is extremely useful in making rapid adjustments in the electron microscope. CCDs provide high sensitivity (useful for minimising dosage to radiation-sensitive biological specimen), good resolution, stable performance, excellent dynamic range and linearity and a reasonably fast readout. We have built an electron imaging device based on the EEV 1152 by 814 pixel CCD which is controlled from a unix based SUN Sparestation operating under X-Windows. The incident 100 kV electrons are converted to visible light in a 0.5 mm thick YAG single crystal which is imaged through a lens on to the CCD. The CCD electronics is designed to be as flexible as possible and allows a wide variation in the readout speed to cater for the relatively fast application where readout noise is less critical and low readout noise applications where the extra few seconds of readout time are not significant. The CCD electronics is built in VME format which is controlled through a S-bus to VME driver. With two parallel channels of readout the whole image can be read out in ˜ 1 s (using the faster readout speed) with 16 bit precision and the image is displayed under X-Windows in a few seconds. The present readout works at 500 kHz and has a noise of ˜ 30 e rms per pixel. With a Peltier cooling device we can operate the CCD at ˜ -40°C which reduces the dark current adequately to allow exposures of up to several minutes. Several examples of patterns collected with the system on a Philips CM12 microscope will be presented.

  19. Studies of dielectrics on graphite and large-area graphene

    NASA Astrophysics Data System (ADS)

    Pirkle, Adam R.

    Graphene is a promising material as an alternative to Si in future logic devices due to extremely high carrier mobility and other attractive physical and electronic properties. While the exact structure of commercially viable graphene-based device architectures is not yet clear, adoption of graphene in such an architecture will certainly require the deposition of scaled dielectrics. Numerous challenges arise, many due to the surface chemistry of graphene which is dramatically different from that of bulk semiconductors due to the absence of bonding states resulting from the two-dimensional nature of sp2 C-C bonds in graphene. The low surface reactivity means that application of conventional dielectric deposition processes generally results in poor, non-uniform nucleation, hindering dielectric scaling below thicknesses of 20-50 nm. This dissertation focuses on studies of the graphene surface and potential routes to scalable dielectric deposition by means of atomic layer deposition (ALD) and physical vapor deposition (PVD). The role of initial surface condition and cleanliness is considered, and several approaches for the formation of dielectric nucleation layers are studied. Several physical and electrical techniques are employed including x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, atomic force microscopy (AFM) and electrical characterization of graphene FETs and capacitors. Additionally, the lack of commercial availability of high quality large-area graphene samples required for these dielectric studies led to the development of in-house capability for CVD growth of graphene on copper substrates and transfer to insulating substrates. Studies of this growth and transfer process are presented.

  20. Evaluating biodiversity conservation around a large Sumatran protected area.

    PubMed

    Linkie, Matthew; Smith, Robert J; Zhu, Yu; Martyr, Deborah J; Suedmeyer, Beth; Pramono, Joko; Leader-Williams, Nigel

    2008-06-01

    Many of the large, donor-funded community-based conservation projects that seek to reduce biodiversity loss in the tropics have been unsuccessful. There is, therefore, a need for empirical evaluations to identify the driving factors and to provide evidence that supports the development of context-specific conservation projects. We used a quantitative approach to measure, post hoc, the effectiveness of a US$19 million Integrated Conservation and Development Project (ICDP) that sought to reduce biodiversity loss through the development of villages bordering Kerinci Seblat National Park, a UNESCO World Heritage Site in Indonesia. We focused on the success of the ICDP component that disbursed a total of US$1.5 million through development grants to 66 villages in return for their commitment to stop illegally clearing the forest. To investigate whether the ICDP lowered deforestation rates in focal villages, we selected a subset of non-ICDP villages that had similar physical and socioeconomic features and compared their respective deforestation rates. Village participation in the ICDP and its development schemes had no effect on deforestation. Instead, accessible areas where village land-tenure had been undermined by the designation of selective-logging concessions tended to have the highest deforestation rates. Our results indicate that the goal of the ICDP was not met and, furthermore, suggest that both law enforcement inside the park and local property rights outside the park need to be strengthened. Our results also emphasize the importance of quantitative approaches in helping to inform successful and cost-effective strategies for tropical biodiversity conservation. PMID:18336620

  1. Cause of large negative Eu anomaly in the highly evolved A-type granites with REE tetrad pattern

    NASA Astrophysics Data System (ADS)

    Lee, S.; Asahara, Y.; Tanaka, T.; Lee, M.; Lee, S. R.

    2013-12-01

    REE tetrad pattern with strongly large negative Eu anomaly is one of the specific geochemical phenomena observed in the highly evolved, fractionated granite or A-type granite. The large negative Eu anomaly from the highly evolved or fractionated granites related with REE tetrad effect was discussed in a lot of literatures (e.g. [1] Muecke and Clarke, 1981; [2] Irber, 1999; [3] Jahn et al., 2001). Recently, Lee et al.[4] also suggested that Eu anomalies and REE tetrad pattern from the highly fractionated A-type Muamsa and Weolaksan granites in the Okcheon Metamorphic Belt, Korea, might be associated with a fractionation between the residual melt and a coexisting aqueous high temperature fluid. Their origin and geochemical significance are ongoing yet. In order to clarify cause of large negative Eu anomaly in the granite with REE tetrad effect more clearly, we reanalyzed REE abundance of the Muamsa and Weolaksan granites using MC-ICP-MS at the origins laboratory of the University of Chicago. We also measured REE abundances of the constituent minerals using quadruple ICP-MS at the Korea Polar Research Institute. In this report, we show the re-analyzed REE data from the whole rock as well as new REE data from constituent minerals of the granite with REE tetrad effect. Then, we discuss the cause of large negative Eu anomaly in the highly evolved granite with REE tetrad effect. Especially, the granites with very large negative Eu anomaly also show large negative Ce anomaly. Lee et al. [4] mentioned that negative Ce anomalies were formed after granite emplacement. However, our new data indicate that negative Ce anomaly might be formed during the same geochemical process with very large negative Eu anomaly. This suggests that the REE tetrad effect may be related with a change of oxidation state during a magma evolution. Therefore, we will discuss REE tetrad effect, negative Eu and Ce anomaly as an indicator for the change of oxidation state of magma during the emplacement

  2. [Spatiotemporal distribution of negative air ion concentration in urban area and related affecting factors: a review].

    PubMed

    Huang, Xiang-Hua; Wang, Jian; Zeng, Hong-Da; Chen, Guang-Shui; Zhong, Xian-Fang

    2013-06-01

    Negative air ion (NAI) concentration is an important indicator comprehensively reflecting air quality, and has significance to human beings living environment. This paper summarized the spatiotemporal distribution features of urban NAI concentration, and discussed the causes of these features based on the characteristics of the environmental factors in urban area and their effects on the physical and chemical processes of NAI. The temporal distribution of NAI concentration is mainly controlled by the periodic variation of solar radiation, while the spatial distribution of NAI concentration along the urban-rural gradient is mainly affected by the urban aerosol distribution, underlying surface characters, and urban heat island effect. The high NAI concentration in urban green area is related to the vegetation life activities and soil radiation, while the higher NAI concentration near the water environment is attributed to the water molecules that participate in the generation of NAI through a variety of ways. The other environmental factors can also affect the generation, life span, component, translocation, and distribution of NAI to some extent. To increase the urban green space and atmospheric humidity and to maintain the soil natural attributes of underlying surface could be the effective ways to increase the urban NAI concentration and improve the urban air quality. PMID:24066568

  3. Automated Science Processing for the Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Chiang, James

    2012-03-01

    The Large Area Telescope (LAT) onboard the Fermi γ-ray Space Telescope provides high sensitivity to emission from astronomical sources over a broad energy range (20MeV to >300 GeV) and has substantially improved spatial, energy, and timing resolution compared with previous observatories at these energies [4]. One of the LAT's most innovative features is that it performs continuous monitoring of the gamma-ray sky with all-sky coverage every 3 h. This survey strategy greatly enables the search for transient behavior from both previously known and unknown sources. In addition, the constant accumulation of data allows for increasingly improved measurements of persistent sources. These include the Milky Way Galaxy itself, which produces gamma-ray emission as a result from interactions of cosmic rays with gas in the Galaxy, and potential signals from candidate dark matter particles in the Milky Way and its neighboring galaxies. The automated science processing (ASP) functionality of the Fermi Instrument Science Operations Center (ISOC) is a part of the automated data pipeline that processes the raw data arriving from the spacecraft and puts it into a form amenable to scientific analysis. ASP operates at the end of the pipeline on the processed data and is intended to detect and characterize transient behavior (e.g., short time scale increases or “flares” in the gamma-ray flux) from astronomical sources. On detection of a flaring event, ASP will alert other observatories on a timely basis so that they may train their telescopes on the flaring source in order to detect possible correlated activity in other wavelength bands. Since the data from the LAT is archived and publicly available as soon as it is processed, ASP serves mainly to provide triggers for those follow-up observations; its estimates of the properties of the flaring sources (flux, spectral index, location) need not be the best possible, as subsequent off-line analysis can provide more refined

  4. Resonant RF network antennas for large-area and large-volume inductively coupled plasma sources

    NASA Astrophysics Data System (ADS)

    Hollenstein, Ch; Guittienne, Ph; Howling, A. A.

    2013-10-01

    Large-area and large-volume radio frequency (RF) plasmas are produced by different arrangements of an elementary electrical mesh consisting of two conductors interconnected by a capacitor at each end. The obtained cylindrical and planar RF networks are resonant and generate very high RF currents. The input impedance of such RF networks shows the behaviour of an RLC parallel resonance equivalent circuit. The real impedance at the resonance frequency is of great advantage for power matching compared with conventional inductive devices. Changes in the RLC equivalent circuit during the observed E-H transition will allow future interpretation of the plasma-antenna coupling. Furthermore, high power transfer efficiencies are found during inductively coupled plasma (ICP) operation. For the planar RF antenna network it is shown that the E-H transition occurs simultaneously over the entire antenna. The underlying physics of these discharges induced by the resonant RF network antenna is found to be identical to that of the conventional ICP devices described in the literature. The resonant RF network antenna is a new versatile plasma source, which can be adapted to applications in industry and research.

  5. The Spitzer-HETDEX Exploratory Large-area Survey

    NASA Astrophysics Data System (ADS)

    Papovich, C.; Shipley, H. V.; Mehrtens, N.; Lanham, C.; Lacy, M.; Ciardullo, R.; Finkelstein, S. L.; Bassett, R.; Behroozi, P.; Blanc, G. A.; de Jong, R. S.; DePoy, D. L.; Drory, N.; Gawiser, E.; Gebhardt, K.; Gronwall, C.; Hill, G. J.; Hopp, U.; Jogee, S.; Kawinwanichakij, L.; Marshall, J. L.; McLinden, E.; Mentuch Cooper, E.; Somerville, R. S.; Steinmetz, M.; Tran, K.-V.; Tuttle, S.; Viero, M.; Wechsler, R.; Zeimann, G.

    2016-06-01

    We present post-cryogenic Spitzer imaging at 3.6 and 4.5 μm with the Infrared Array Camera (IRAC) of the Spitzer/HETDEX Exploratory Large-Area (SHELA) survey. SHELA covers ≈24 deg2 of the Sloan Digital Sky Survey “Stripe 82” region, and falls within the footprints of the Hobby–Eberly Telescope Dark Energy Experiment (HETDEX) and the Dark Energy Survey. The HETDEX blind R ∼ 800 spectroscopy will produce ∼200,000 redshifts from the Lyα emission for galaxies in the range 1.9 < z < 3.5, and an additional ∼200,000 redshifts from the [O ii] emission for galaxies at z < 0.5. When combined with deep ugriz images from the Dark Energy Camera, K-band images from NEWFIRM, and other ancillary data, the IRAC photometry from Spitzer will enable a broad range of scientific studies of the relationship between structure formation, galaxy stellar mass, halo mass, the presence of active galactic nuclei, and environment over a co-moving volume of ∼0.5 Gpc3 at 1.9 < z < 3.5. Here, we discuss the properties of the SHELA IRAC data set, including the data acquisition, reduction, validation, and source catalogs. Our tests show that the images and catalogs are 80% (50%) complete to limiting magnitudes of 22.0 (22.6) AB mag in the detection image, which is constructed from the weighted sum of the IRAC 3.6 and 4.5 μm images. The catalogs reach limiting sensitivities of 1.1 μJy at both 3.6 and 4.5 μm (1σ, for R = 2″ circular apertures). As a demonstration of the science, we present IRAC number counts, examples of highly temporally variable sources, and galaxy surface density profiles of rich galaxy clusters. In the spirit of the Spitzer Exploratory programs, we provide all of the images and catalogs as part of the publication.

  6. The Spitzer-HETDEX Exploratory Large-area Survey

    NASA Astrophysics Data System (ADS)

    Papovich, C.; Shipley, H. V.; Mehrtens, N.; Lanham, C.; Lacy, M.; Ciardullo, R.; Finkelstein, S. L.; Bassett, R.; Behroozi, P.; Blanc, G. A.; de Jong, R. S.; DePoy, D. L.; Drory, N.; Gawiser, E.; Gebhardt, K.; Gronwall, C.; Hill, G. J.; Hopp, U.; Jogee, S.; Kawinwanichakij, L.; Marshall, J. L.; McLinden, E.; Mentuch Cooper, E.; Somerville, R. S.; Steinmetz, M.; Tran, K.-V.; Tuttle, S.; Viero, M.; Wechsler, R.; Zeimann, G.

    2016-06-01

    We present post-cryogenic Spitzer imaging at 3.6 and 4.5 μm with the Infrared Array Camera (IRAC) of the Spitzer/HETDEX Exploratory Large-Area (SHELA) survey. SHELA covers ≈24 deg2 of the Sloan Digital Sky Survey “Stripe 82” region, and falls within the footprints of the Hobby–Eberly Telescope Dark Energy Experiment (HETDEX) and the Dark Energy Survey. The HETDEX blind R ˜ 800 spectroscopy will produce ˜200,000 redshifts from the Lyα emission for galaxies in the range 1.9 < z < 3.5, and an additional ˜200,000 redshifts from the [O ii] emission for galaxies at z < 0.5. When combined with deep ugriz images from the Dark Energy Camera, K-band images from NEWFIRM, and other ancillary data, the IRAC photometry from Spitzer will enable a broad range of scientific studies of the relationship between structure formation, galaxy stellar mass, halo mass, the presence of active galactic nuclei, and environment over a co-moving volume of ˜0.5 Gpc3 at 1.9 < z < 3.5. Here, we discuss the properties of the SHELA IRAC data set, including the data acquisition, reduction, validation, and source catalogs. Our tests show that the images and catalogs are 80% (50%) complete to limiting magnitudes of 22.0 (22.6) AB mag in the detection image, which is constructed from the weighted sum of the IRAC 3.6 and 4.5 μm images. The catalogs reach limiting sensitivities of 1.1 μJy at both 3.6 and 4.5 μm (1σ, for R = 2″ circular apertures). As a demonstration of the science, we present IRAC number counts, examples of highly temporally variable sources, and galaxy surface density profiles of rich galaxy clusters. In the spirit of the Spitzer Exploratory programs, we provide all of the images and catalogs as part of the publication.

  7. A technology program for large area space systems

    NASA Technical Reports Server (NTRS)

    Guastaferro, A.; Jenkins, L. M.

    1978-01-01

    The large space systems technology program (LSST) is discussed. The purpose of LSST is to define and develop technology for large space systems and associated subsystems required for projected NASA space missions. Goals involving structural concepts and supporting technology are surveyed. The application of LSST to the design of the solar power satellite is considered.

  8. Large area controlled assembly of transparent conductive networks

    DOEpatents

    Ivanov, Ilia N.; Simpson, John T.

    2015-09-29

    A method of preparing a network comprises disposing a solution comprising particulate materials in a solvent onto a superhydrophobic surface comprising a plurality of superhydrophobic features and interfacial areas between the superhydrophobic features. The plurality of superhydrophobic features has a water contact angle of at least about 150.degree.. The method of preparing the network also comprises removing the solvent from the solution of the particulate materials, and forming a network of the particulate materials in the interfacial areas, the particulate materials receding to the interfacial areas as the solvent is removed.

  9. Geotechnical conditions contributing to negative geological process development in urban areas (the case of Kemerovo-city)

    NASA Astrophysics Data System (ADS)

    Leonova, A. V.; Khabibullin, R. R.; Baranova, A. V.

    2016-03-01

    The paper addresses the issue of intensive urban development in the area of Kemerovo-city. Underestimation of geotechnical conditions of the area at the project and construction stages results in negative geological processes such as erosion, waterlogging, soil subsidence, and underflooding. These processes can lead to deformation and failure of buildings and constructions.

  10. Negative symptoms in schizophrenia: a study in a large clinical sample of patients using a novel automated method

    PubMed Central

    Patel, Rashmi; Jayatilleke, Nishamali; Broadbent, Matthew; Chang, Chin-Kuo; Foskett, Nadia; Gorrell, Genevieve; Hayes, Richard D; Jackson, Richard; Johnston, Caroline; Shetty, Hitesh; Roberts, Angus; McGuire, Philip; Stewart, Robert

    2015-01-01

    Objectives To identify negative symptoms in the clinical records of a large sample of patients with schizophrenia using natural language processing and assess their relationship with clinical outcomes. Design Observational study using an anonymised electronic health record case register. Setting South London and Maudsley NHS Trust (SLaM), a large provider of inpatient and community mental healthcare in the UK. Participants 7678 patients with schizophrenia receiving care during 2011. Main outcome measures Hospital admission, readmission and duration of admission. Results 10 different negative symptoms were ascertained with precision statistics above 0.80. 41% of patients had 2 or more negative symptoms. Negative symptoms were associated with younger age, male gender and single marital status, and with increased likelihood of hospital admission (OR 1.24, 95% CI 1.10 to 1.39), longer duration of admission (β-coefficient 20.5 days, 7.6–33.5), and increased likelihood of readmission following discharge (OR 1.58, 1.28 to 1.95). Conclusions Negative symptoms were common and associated with adverse clinical outcomes, consistent with evidence that these symptoms account for much of the disability associated with schizophrenia. Natural language processing provides a means of conducting research in large representative samples of patients, using data recorded during routine clinical practice. PMID:26346872

  11. A technology program for large area space systems

    NASA Technical Reports Server (NTRS)

    Guastaferro, A.

    1979-01-01

    The broad objective of the Large Space Systems Technology (LSST) program is to define and develop the necessary technology for large space systems and associated subsystems required for projected NASA space missions. It is a goal of LSST to make these systems economically and technically feasible by focusing on those technical activities believed to provide the greatest benefit to a variety of future systems. Emphasis is placed on two principal structural configurations: antennas and platforms.

  12. Gate-tunable large negative tunnel magnetoresistance in Ni-C60-Ni single molecule transistors.

    PubMed

    Yoshida, Kenji; Hamada, Ikutaro; Sakata, Shuichi; Umeno, Akinori; Tsukada, Masaru; Hirakawa, Kazuhiko

    2013-02-13

    We have fabricated single C(60) molecule transistors with ferromagnetic Ni leads (FM-SMTs) by using an electrical break junction method and investigated their magnetotransport. The FM-SMTs exhibited clear gate-dependent hysteretic tunnel magnetoresistance (TMR) and the TMR values reached as high as -80%. The polarity of the TMR was found to be always negative over the entire bias range studied here. Density functional theory calculations show that hybridization between the Ni substrate states and the C(60) molecular orbitals generates an antiferromagnetic configuration in the local density of states near the Fermi level, which gives a reasonable explanation for the observed negative TMR. PMID:23327475

  13. Design and fabrication of a large magnetic cusp type of plasma generator for the production of negative ions

    SciTech Connect

    Biagi, L.A.; Ehlers, K.W.; Leung, K.N.; Matuk, C.A.; Moon, S.D.; Paterson, J.A.

    1981-10-01

    The design and fabrication techniques for a large magnetic bucket type of plasma source designed for the production of negative ions by surface conversion are described. These include the design of a converter structure, cesium oven and injector, variable aperture electrode, accelerator section as well as the features of the magnetic cusp geometry employed.

  14. Large-Area, Highly Ordered Array of Graphitic Carbon Materials Using Surface Active Chitosan Prepatterns.

    PubMed

    Baek, Youn-Kyoung; Kim, Dae Woo; Yang, Seung Bo; Lee, Jung-Goo; Kim, Young Kuk; Jung, Hee-Tae

    2015-02-01

    We demonstrate that chitosan prepatterns can generate not only highly periodic DNA pattern but also various types of graphitic carbon materials such as single-walled carbon nanotubes (SWNTs), graphene oxide (GO) and reduced graphene oxide (RGO). Scanning electron microscopy (SEM), fluorescence imaging and Raman spectroscopic results revealed that the graphitic carbon materials were selectively deposited on the surface of the periodic chitosan patterns by the electrostatic interaction between protonated amine groups of chitosan and the negative charged carbon materials. One proof-of-concept application of the system to the fabrication of electrical devices based on the micropatterns of SWNTs and RGO was also demonstrated. The strategy to use highly surface active chitosan pattern that can easily fabricate highly periodic pattern via a variety of lithographic tools may pave the way for the production of periodic arrays of graphitic carbon materials for large area device integration. PMID:26353637

  15. The Negative Binomial Distribution as a Renewal Model for the Recurrence of Large Earthquakes

    NASA Astrophysics Data System (ADS)

    Tejedor, Alejandro; Gómez, Javier B.; Pacheco, Amalio F.

    2015-01-01

    The negative binomial distribution is presented as the waiting time distribution of a cyclic Markov model. This cycle simulates the seismic cycle in a fault. As an example, this model, which can describe recurrences with aperiodicities between 0 and 0.5, is used to fit the Parkfield, California earthquake series in the San Andreas Fault. The performance of the model in the forecasting is expressed in terms of error diagrams and compared with other recurrence models from literature.

  16. Large area 200 psec gated microchannel plate detector

    SciTech Connect

    Eckart, M.J.; Hanks, R.L.; Kilkenny, J.D.; Pasha, R.; Wiedwald, J.D.; Hares, J.D.

    1986-03-01

    Results are presented with a 15 mm wide gated microchannel plate uv and x-ray detector. The active area is part of a 6 ohm transmission line driven by an electronically generated gate pulse. The microchannel plate is coated with CsI allowing tests with a frequency quadrupled, high repetition rate 1.05 ..mu..m laser. Results showing optical gate widths as short as 100 psec are presented.

  17. Large-area 200-ps gated microchannel plate detector

    SciTech Connect

    Eckart, M.J.; Hanks, R.L.; Kilkenny, J.D.; Pasha, R.; Wiedwald, J.D.; Hares, J.D.

    1986-08-01

    Results are presented with a 15-mm-wide gated microchannel plate UV and x-ray detector. The active area is part of a 6-..cap omega.. transmission line driven by an electronically generated gate pulse. The microchannel plate is coated with CsI allowing tests with a frequency-quadrupoled, high-repetition-rate 1.05-..mu..m laser. Results showing optical gate widths as short as 100 ps are presented.

  18. Composite flexible skin with large negative Poisson’s ratio range: numerical and experimental analysis

    NASA Astrophysics Data System (ADS)

    Chen, Y. J.; Scarpa, F.; Farrow, I. R.; Liu, Y. J.; Leng, J. S.

    2013-04-01

    This paper describes the manufacturing, characterization and parametric modeling of a novel fiber-reinforced composite flexible skin with in-plane negative Poisson’s ratio (auxetic) behavior. The elastic mechanical performance of the auxetic skin is evaluated using a three-dimensional analytical model based on the classical laminate theory (CLT) and Sun’s thick laminate theory. Good agreement is observed between in-plane Poisson’s ratios and Young’s moduli of the composite skin obtained by the theoretical model and the experimental results. A parametric analysis carried out with the validated model shows that significant changes in the in-plane negative Poisson’s ratio can be achieved through different combinations of matrix and fiber materials and stacking sequences. It is also possible to identify fiber-reinforced composite skin configurations with the same in-plane auxeticity but different orthotropic stiffness performance, or the same orthotropic stiffness performance but different in-plane auxeticity. The analysis presented in this work provides useful guidelines to develop and manufacture flexible skins with negative Poisson’s ratio for applications focused on morphing aircraft wing designs.

  19. A description of rainfall interception over large areas

    NASA Technical Reports Server (NTRS)

    Eltahir, E. A. B.; Bras, R. L.

    1993-01-01

    A new scheme is developed for describing interception at spatial scales comparable to the typical resolution of climate models. The scheme is based on the Rutter model of interception and statistical description of the subgrid-scale spatial variability of canopy storage and rainfall. The interception loss simulated by the new scheme is significantly smaller than those simulated by other schemes that do not include considerations for spatial variability. The explanation of this result is partly in the enhancement of spatially averaged canopy drainage due to the large local drainage from the few buckets of large canopy storage. The relative reduction in interception loss simulated by the new scheme may explain the overestimation of interception loss by climate models that do not include the effects of spatial variability on interception processes.

  20. Cleaning of large area by excimer laser ablation

    NASA Astrophysics Data System (ADS)

    Sentis, Marc L.; Delaporte, Philippe C.; Marine, Wladimir I.; Uteza, Olivier P.

    2000-01-01

    Surface removal technologies are being challenged from environmental and economic perspectives. This paper is concerned with laser ablation applied to large surface cleaning with an automatized excimer laser unit. The study focused on metallic surfaces that are oxidized and are representative of contaminated surfaces with radionuclides in a context of nuclear power plant maintenance. The whole system is described: laser, beam deliver, particle collection cell, real time control of cleaning processes. Results concerning surface laser interaction and substrate modifications are presented.

  1. Heat-Pipe Array for Large-Area Cooling

    NASA Technical Reports Server (NTRS)

    Edelstein, F.; Brown, R. F.

    1986-01-01

    High rates of heat transfer anticipated. Prototype evaporative cold plate gathers waste heat from equipment mounted on it. Plate made by welding together flanges of several sections of heat pipe. Since plate separates liquid and vapor phases at inlet and outlet ports, eliminates complexities and uncertainties of two-phase flow in zero gravity. On earth, inlet valve enables plate to operate at relatively-large height differences with other plates in same system.

  2. Avian surveys of large geographical areas: A systematic approach

    USGS Publications Warehouse

    Scott, J.M.; Jacobi, J.D.; Ramsey, F.L.

    1981-01-01

    A multidisciplinary team approach was used to simultaneously map the distribution of birds, selected food items, and major vegetation types in 34,000- to 140,000-ha tracts in native Hawaiian forests. By using a team approach, large savings in time can be realized over attempts to conduct similar surveys of smaller scope, and a systems approach to management problems is made easier. The methods used in survey design, training observers, and documenting bird numbersand habitat descriptions are discussed in detail.

  3. A new approach to large area microchannel plate manufacture

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Methods of manufacture of twisted single elements as the base for producing microchannel plates (MCP) are discussed. Initial evaluations validated the off-axis channel concept and no technological roadblocks were identified which would prevent fabrication of high gain, high spatial resolution, large format MCP's using this technique. The first MP's have operated at stable gains of 3 million with pulse height resolution superior to results obtained by standard chevron MCP's.

  4. Progress in amorphous silicon based large-area multijunction modules

    SciTech Connect

    Carlson, D.E.; Arya, R.R.; Bennett, M.; Chen, L.; Jansen, K.; Li, Y.; Maley, N.; Morris, J.; Newton, J.; Oswald, R.S.; Rajan, K.; Vezzetti, D.; Willing, F.; Yang, L.

    1996-01-01

    Solarex, a business unit of Amoco/Enron Solar, is scaling up its a-Si:H/a-SiGe:H tandem device technology for the production of 8 ft{sup 2} modules. The current R&D effort is focused on improving the performance, reliability and cost-effectiveness of the tandem junction technology by systematically optimizing the materials and interfaces in small-area single- and tandem junction cells. Average initial conversion efficiencies of 8.8{percent} at 85{percent} yield have been obtained in pilot production runs with 4 ft{sup 2} tandem modules. {copyright} {ital 1996 American Institute of Physics.}

  5. Progress in amorphous silicon based large-area multijunction modules

    NASA Astrophysics Data System (ADS)

    Carlson, D. E.; Arya, R. R.; Bennett, M.; Chen, L.-F.; Jansen, K.; Li, Y.-M.; Maley, N.; Morris, J.; Newton, J.; Oswald, R. S.; Rajan, K.; Vezzetti, D.; Willing, F.; Yang, L.

    1996-01-01

    Solarex, a business unit of Amoco/Enron Solar, is scaling up its a-Si:H/a-SiGe:H tandem device technology for the production of 8 ft2 modules. The current R&D effort is focused on improving the performance, reliability and cost-effectiveness of the tandem junction technology by systematically optimizing the materials and interfaces in small-area single- and tandem junction cells. Average initial conversion efficiencies of 8.8% at 85% yield have been obtained in pilot production runs with 4 ft2 tandem modules.

  6. Large area low-cost space solar cell development

    NASA Technical Reports Server (NTRS)

    Barona, C. R.; Cioni, J. L.

    1982-01-01

    A development program to produce 5.9 x 5.9 cm space quality silicon solar cells with a cost goal of 30 $/W is described. Cell types investigated include wraparound dielectric, mechanical wraparound and conventional contact configurations with combinations of 2 or 10 ohm/cm resistivity, back surface reflectors and/or fields, and diffused or ion implanted junctions. A single step process to cut cell and cover glass simultaneously is being developed. Results for cell and array tests are given. Large solar arrays that might use cells of this type are discussed.

  7. Acrolein Microspheres Are Bonded To Large-Area Substrates

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan; Yen, Richard C. K.

    1988-01-01

    Reactive cross-linked microspheres produced under influence of ionizing radiation in aqueous solutions of unsaturated aldehydes, such as acrolein, with sodium dodecyl sulfate. Diameters of spheres depend on concentrations of ingredients. If polystyrene, polymethylmethacrylate, or polypropylene object immersed in solution during irradiation, microspheres become attached to surface. Resulting modified surface has grainy coating with reactivity similar to free microspheres. Aldehyde-substituted-functional microspheres react under mild conditions with number of organic reagents and with most proteins. Microsphere-coated macrospheres or films used to immobilize high concentrations of proteins, enzymes, hormones, viruses, cells, and large number of organic compounds. Applications include separation techniques, clinical diagnostic tests, catalytic processes, and battery separators.

  8. Rapid fabrication of large area binary polystyrene colloidal crystals

    NASA Astrophysics Data System (ADS)

    Luo, Chun-Li; Yang, Rui-Xia; Yan, Wei-Guo; Zhao, Jian; Yang, Guang-Wu; Jia, Guo-Zhi

    2016-07-01

    Binary colloidal crystals (BCCs) possess great potentials in tuning material and optical properties. In this paper, the combination of interface transferred method and spin-coating method is used to fabricate BCCs with different patterns via controlling the size ratio of small (S) to large (L) colloidal spheres and the spin speeds. It is found that BCCs formed LS2, LS4 and LS6 by changing the size ratio. In addition, there are some new and complicated structures, such as LS12, Janus arrays, formed at the low spin speed. This simple assembly method has potential to allow for the creation of optical metmaterials and the plasmonic structures with chiral optical properties.

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

    SciTech Connect

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

    1984-03-01

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

  10. Large and negative Goos-Hänchen shift with magneto-controllability based on a ferrofluid

    NASA Astrophysics Data System (ADS)

    Fu, Mengshi; Zhang, Yu; Wu, Jipeng; Dai, Xiaoyu; Xiang, Yuanjiang

    2013-03-01

    We report on the Goos-Hänchen (GH) shift of a beam reflected from ferrofluids composed of Fe3O4 nanoparticles coated with Ag, based on the stationary-phase method. We found that both the magneto and structural approaches can effectively control the GH shift. In particular, a larger negative GH shift can be obtained by changing the external magnetic field and the volume factor. The magneto-controllable GH shift provides a possibility for obtaining a desirable GH shift in a fixed configuration.

  11. Large Area Dust Detector onboard Solar Power Sail Spacecraft

    NASA Astrophysics Data System (ADS)

    Yano, Hajime

    JAXA is aiming to launch the solar power sail engineering demonstrator to the outer planet region of the solar system like Jupiter and the Jovian Trojan asteroids in 2010's. Its interplanetary cruise is a relevant and rare opportunity to monitor physical properties that may be varied by heliocentric distances continuously such as solar wind, solar magnetosphere and micrometeoroid flux. We have been developing the largest but still light-weight dust detector ever to be onboard deep space probes since 2000. PVDF films of a few to 10's of micron thickness are attached as a small part of the solar sail membrane to count and time hypervelocity impacts by micrometeoroids larger than micron size. The first spaceflight test of this dust detector in the order of 100 cm2 detection area was conducted onboard SSSAT (Solar Sail Satellite) as the M-V sub-payload launched to LEO in September 2006. The second opportunity of this series will be the 4- channel impact sensors onboard Kagayaki nano-satellite as an H-IIA piggyback to be launched in 2008. Actual interplanetary measurements can be achieved by the Small Solar Power Sail Demonstrator that will go inside the orbit of the Earth (1 AU) close to Venus around 2010. On this spacecraft, the 8-channel PVDF sensors of about 1 m2 detection area will be onboard to test this system in the interplanetary operation and to hopefully measure dust flux anisotropy in the trailing edge of the Earth, heliocentric flux variance inside 1 AU, and opportunistic detections of possible cometary dust trails and flux enhancement near Venus. The sensors filter electronic, thermal and vibration noises and record time, peak hold value, and relax duration of signals of micrometeoroid impacts. When the full-size solar power sail mission goes beyond 1 AU passing the main asteroid belt to 5 AU in 2010's, this dust detector system will be onboard in the order of several m2 active area. It will also compare its results with infrared observation of zodiacal

  12. Andean Basins Morphometry: Assesing South American Large Rivers' Source Areas

    NASA Astrophysics Data System (ADS)

    Bean, R. A.; Latrubesse, E. M.

    2014-12-01

    Presently there are no regional-scale morphometric analyses of Andean fluvial basins. Therefore, we created a continental-scale database of these basins. Our data covers over an area 1,000,000 km2 of the Andes, from Venezuela to Argentina. These basins are the source of some of the largest rivers in the world including the Amazon, Orinoco, Parana, and Magdalena. Morphometric parameters including shape factor, relief ratio, longitudinal profiles and different indices of basin elevation were calculated based on the CGIAR SRTM 4.1 DEM (~90 m resolution). FAO Hydrosheds were used to segment the DEM by major catchment and then manually cut at the Andean zone. In the North and Central Andes, this produced over 500,000 subcatchments, which we reduced to 619 by setting minimum catchment area to 100 km2. We then integrate lithologic data from DNPM geologic data. Our results indicate that sedimentary lithologies dominate Central Andean catchments (n=268,k=4), which cover an area 767,00 km2, while the Northern Andean catchments (covering 350,000 km2) are more varied, dominated by volcanics in the Pacific (n=78), a sedimentary (48%) dominant mix in the Caribbean (n=138) and 60% sedimentary in the Amazon-Orinoco subregion catchments (n=138). Elevation averages are smallest in the north Andes and average maximum elevations (6,026 m) in the Argentinian catchments (n=65) of the Central Andes are the highest. Shape factors range from 0.49 to 0.58 in the North and 0.52 to 0.58 in the Central Andes. There are clear differences in all categories between region and subregion, but that difference does not hinge on a single morphometric or geologic parameter. Morphometric parameters at a watershed scale (listed in Table) are analyzed and hydrologic data from gauging stations throughout the Andes (n=100) are used to compare morphometric parameters with lithology and characteristics from the basin hydrograph (peak discharge timing, minimum and maximum discharge, and runoff).

  13. Hydrogen atom temperature measured with wavelength-modulated laser absorption spectroscopy in large scale filament arc negative hydrogen ion source

    SciTech Connect

    Nakano, H. Goto, M.; Tsumori, K.; Kisaki, M.; Ikeda, K.; Nagaoka, K.; Osakabe, M.; Takeiri, Y.; Kaneko, O.; Nishiyama, S.; Sasaki, K.

    2015-04-08

    The velocity distribution function of hydrogen atoms is one of the useful parameters to understand particle dynamics from negative hydrogen production to extraction in a negative hydrogen ion source. Hydrogen atom temperature is one of the indicators of the velocity distribution function. To find a feasibility of hydrogen atom temperature measurement in large scale filament arc negative hydrogen ion source for fusion, a model calculation of wavelength-modulated laser absorption spectroscopy of the hydrogen Balmer alpha line was performed. By utilizing a wide range tunable diode laser, we successfully obtained the hydrogen atom temperature of ∼3000 K in the vicinity of the plasma grid electrode. The hydrogen atom temperature increases as well as the arc power, and becomes constant after decreasing with the filling of hydrogen gas pressure.

  14. Large-area sheet task advanced dendritic web growth development

    NASA Technical Reports Server (NTRS)

    Duncan, C. S.; Seidensticker, R. G.; Mchugh, J. P.

    1984-01-01

    The thermal models used for analyzing dendritic web growth and calculating the thermal stress were reexamined to establish the validity limits imposed by the assumptions of the models. Also, the effects of thermal conduction through the gas phase were evaluated and found to be small. New growth designs, both static and dynamic, were generated using the modeling results. Residual stress effects in dendritic web were examined. In the laboratory, new techniques for the control of temperature distributions in three dimensions were developed. A new maximum undeformed web width of 5.8 cm was achieved. A 58% increase in growth velocity of 150 micrometers thickness was achieved with dynamic hardware. The area throughput goals for transient growth of 30 and 35 sq cm/min were exceeded.

  15. Wide-area ATM networking for large-scale MPPs

    SciTech Connect

    Papadopoulos, P.M.; Geist, G.A. II

    1997-04-01

    This paper presents early experiences with using high-speed ATM interfaces to connect multiple Intel Paragons on both local and wide area networks. The testbed includes the 1024 and 512 node Paragons running the OSF operating system at Oak Ridge National Laboratory and the 1840 node Paragon running the Puma operating system at Sandia National Laboratories. The experimental OC-12 (622 Mbits/sec) interfaces are built by GigaNet and provide a proprietary API for sending AAL-5 encapsulated packets. PVM is used as the massaging infrastructure and significant modifications have been made to use the GigaNet API, operate in the Puma environment, and attain acceptable performance over local networks. These modifications are described along with a discussion of roadblocks to networking MPPs with high-performance interfaces. Our early prototype utilizes approximately 25 percent of an OC-12 circuit and 80 percent of an OC-3 circuit in send plus acknowledgment ping-pong tests.

  16. Communications performance of an undersea acoustic large-area network

    NASA Astrophysics Data System (ADS)

    Kriewaldt, Hannah A.; Rice, Joseph A.

    2005-04-01

    The U.S. Navy is developing Seaweb acoustic networking capability for integrating undersea systems. Seaweb architectures generally involve a wide-area network of fixed nodes consistent with future distributed autonomous sensors on the seafloor. Mobile nodes including autonomous undersea vehicles (AUVs) and submarines operate in the context of the grid by using the fixed nodes as both navigation reference points and communication access points. In October and November 2004, Theater Anti-Submarine Warfare Exercise (TASWEX04) showcased Seaweb in its first fleet appearance. This paper evaluates the TASWEX04 Seaweb performance in support of networked communications between a submarine and a surface ship. Considerations include physical-layer dependencies on the 9-14 kHz acoustic channel, such as refraction, wind-induced ambient noise, and submarine aspect angle. [Work supported by SSC San Diego.

  17. LSSA large area silicon sheet task continuous Czochralski process development

    NASA Technical Reports Server (NTRS)

    Rea, S. N.

    1978-01-01

    A Czochralski crystal growing furnace was converted to a continuous growth facility by installation of a premelter to provide molten silicon flow into the primary crucible. The basic furnace is operational and several trial crystals were grown in the batch mode. Numerous premelter configurations were tested both in laboratory-scale equipment as well as in the actual furnace. The best arrangement tested to date is a vertical, cylindrical graphite heater containing small fused silicon test tube liner in which the incoming silicon is melted and flows into the primary crucible. Economic modeling of the continuous Czochralski process indicates that for 10 cm diameter crystal, 100 kg furnace runs of four or five crystals each are near-optimal. Costs tend to asymptote at the 100 kg level so little additional cost improvement occurs at larger runs. For these conditions, crystal cost in equivalent wafer area of around $20/sq m exclusive of polysilicon and slicing was obtained.

  18. Reconfigurable large-area magnetic vortex circulation patterns

    NASA Astrophysics Data System (ADS)

    Streubel, Robert; Kronast, Florian; Rößler, Ulrich K.; Schmidt, Oliver G.; Makarov, Denys

    2015-09-01

    Magnetic vortices in nanodots own a switchable circulation sense. These nontrivial magnetization configurations can be arranged into extended and interacting patterns. We have experimentally created large arrays of magnetically reconfigurable vortex patterns in nonplanar honeycomb lattices using particle lithography. Optimizing height asymmetry of the vertices and applying an in-plane magnetic field provide means to switch between homocircular and staggered vortex patterns with a potentially high impact on magnonics and spintronics relying on chiral noncollinear spin textures. To this end, exchange coupling of extended vortex lattices with an out-of-plane magnetized layer allows one to realize artificial skyrmionic core textures with controllable circulation and topological properties in extended exchange coupled honeycomb lattices that may pave the way towards magnetic memory and logic devices based on artificial skyrmions.

  19. Large area emulsion chamber experiments for the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Parnell, T. A.

    1985-01-01

    Emulsion-chamber experiments employing nuclear-track emulsions, etchable plastic detectors, metal plates, and X-ray films continue to demonstrate high productivity and potential in the study of cosmic-ray primaries and their interactions. Emulsions, with unsurpassed track-recording capability, provide an appropriate medium for the study of nucleus-nucleus interactions at high energy, which will likely produce observations of a phase change in nuclear matter. The many advantages of emulsion chambers (excellent multitrack recording capability, large geometry factor, low apparatus cost, simplicity of design and construction) are complemented by the major advantages of the Space Shuttle as an experiment carrier. A Shuttle experiment which could make a significant advance in both cosmic-ray primary and nucleus-nucleus interaction studies is described. Such an experiment would serve as a guide for use of emulsions during the Space Station era. Some practical factors that must be considered in planning a Shuttle exposure of emulsion chambers are discussed.

  20. Large area magnetic micropallet arrays for cell colony sorting.

    PubMed

    Cox-Muranami, Wesley A; Nelson, Edward L; Li, G P; Bachman, Mark

    2016-01-01

    A new micropallet array platform for adherent cell colony sorting has been developed. The platform consisted of thousands of square plastic pallets, 270 μm by 270 μm on each side, large enough to hold a single colony of cells. Each pallet included a magnetic core, allowing them to be collected with a magnet after being released using a microscope mounted laser system. The micropallets were patterned from 1002F epoxy resist and were fabricated on translucent, gold coated microscope slides. The gold layer was used as seed for electroplating the ferromagnetic cores within every individual pallet. The gold layer also facilitated the release of each micropallet during laser release. This array allows for individual observation, sorting and collection of isolated cell colonies for biological cell colony research. In addition to consistent release and recovery of individual colonies, we demonstrated stable biocompatibility and minimal loss in imaging quality compared to previously developed micropallet arrays. PMID:26606460

  1. Anti-reflection Coatings on Large Area Glass Sheets

    NASA Technical Reports Server (NTRS)

    Pastirik, E.

    1979-01-01

    The first quarter of a one-year program designed to research and perfect a method of producing antireflective coatings on large glass sheets through the use of sodium silicate hardened by exposure to acid is reported. The requirements for a linear motion device used to produce uniform sodium silicate films were determined. A search for a commercially available device is underway. Sodium silicate solutions of varying concentrations were prepared. Determinations of the physical properties relevant to film thickness are in progress. In addition, material costs are being recorded for later use in a cost analysis of the method. All tasks of the project are proceeding according to schedule. Of the tasks, only the sodium silicate solution preparation is complete.

  2. Large-area polymer replication for microfluidic devices

    NASA Astrophysics Data System (ADS)

    Heckele, Mathias; Gerlach, Andreas; Guber, Andreas E.; Schaller, Thomas

    2001-04-01

    A huge market development is expected for modern drug discovery and genomic analysis when rapid parallel analysis of a large number of samples gets available at affordable costs. The state of the art shows that low cost devices can be fabricated in mass production by micromolding of polymers. In close collaboration, Greiner Bio-One and Forschungszentrum Karlsruhe have developed a single-use plastic microfluidic capillary electrophoresis (CE) array in the standardized microplate footprint. This paper presents the results of experiences which show that hot embossing with a mechanically micromachined molding tool is the appropriate technology for low cost mass fabrication. A subsequent sealing of the microchannels allows sub-microliter sample volumes in 96- channel multiplexed microstructures.

  3. Large area CCD image sensors for space astronomy

    NASA Technical Reports Server (NTRS)

    Schwarzschild, M.

    1979-01-01

    The Defense Advanced Research Projects Agency (DARPA) has a substantial program to develop a 2200 x 2200 pixel CCD (Charge Coupled Device) mosaic array made up of 400 individual CCD's, 110 x 110 pixels square. This type of image sensor appeared to have application in space and ground-based astronomy. Under this grant a CCD television camera system was built which was capable of operating an array of 4 CCD's to explore the suitability of the CCD's to explore the suitability of the CCD for astronomical applications. Two individual packaged CCD's were received and evaluated. Evaluation of the basic characteristics of the best individual chips was encouraging, but the manufacturer found that their yield in manufacturing this design is two low to supply sufficient CDD's for the DARPA mosaic array. The potential utility of large mosaic arrays in astronomy is still substantial and continued monitoring of the manufacturers progress in the coming year is recommended.

  4. Development of a large volume negative-ion source for ITER neutral beam injector

    NASA Astrophysics Data System (ADS)

    Watanabe, K.; Amemiya, T.; Hanada, M.; Iga, T.; Imai, T.; Inoue, T.; Kashiwagi, M.; Kuriyama, M.; Morishita, T.; Okumura, Y.; Takayanagi, T.; Yamamoto, T.

    2002-02-01

    Development of the negative-ion sources has been conducted to realize a high power neutral beam injector for International Thermonuclear Experimental Reactor (ITER). A high negative-ion current density of 31 mA/cm2 (H-) at a very low pressure of 0.1 Pa has been produced in a cesium seeded multicusp plasma generator which has the same concept of the ITER source. For a vacuum insulated accelerator, a voltage holding experiment of long distance vacuum gaps up to ˜1.8 m has been performed. It was clarified that the transition region of product pressure distance (pd) from the vacuum breakdown to the gas discharge is about 0.2 Pa m which is high enough from the operating region of the ITER source. A prototype vacuum insulated accelerator was fabricated based on the experiment and tested. A high-energy H- beam acceleration up to 970 keV, 37 mA, and 1 s has been successfully demonstrated.

  5. Large-scale optimization-based non-negative computational framework for diffusion equations: Parallel implementation and performance studies

    DOE PAGESBeta

    Chang, Justin; Karra, Satish; Nakshatrala, Kalyana B.

    2016-07-26

    It is well-known that the standard Galerkin formulation, which is often the formulation of choice under the finite element method for solving self-adjoint diffusion equations, does not meet maximum principles and the non-negative constraint for anisotropic diffusion equations. Recently, optimization-based methodologies that satisfy maximum principles and the non-negative constraint for steady-state and transient diffusion-type equations have been proposed. To date, these methodologies have been tested only on small-scale academic problems. The purpose of this paper is to systematically study the performance of the non-negative methodology in the context of high performance computing (HPC). PETSc and TAO libraries are, respectively, usedmore » for the parallel environment and optimization solvers. For large-scale problems, it is important for computational scientists to understand the computational performance of current algorithms available in these scientific libraries. The numerical experiments are conducted on the state-of-the-art HPC systems, and a single-core performance model is used to better characterize the efficiency of the solvers. Furthermore, our studies indicate that the proposed non-negative computational framework for diffusion-type equations exhibits excellent strong scaling for real-world large-scale problems.« less

  6. SPLASH: Spitzer Large Area Survey with Hyper-Suprime-Cam

    NASA Astrophysics Data System (ADS)

    Capak, Peter; Aussel, Herve; Bundy, Kevin; Bethermin, Matthieu; Carollo, Marcella; Ram-Chary, Ranga; Civano, Francesca; Coupon, Jean; Diener, Catrina; Donley, Jennifer; Dunlop, Jim; Elvis, Martin; Faisst, Andreas; Foucaud, Sebastien; Green, Jenny; Gunn, Jim; Hashimoto, Yasuhiro; Hassinger, Gunther; Hsieh, Bau-Ching; Huang, Lijin; Ilbert, Olivier; LeFloc'h, Emeric; LeFevre, Olivier; Lilly, Simon; Lin, Lihwai; Lin, Yen-Ting; Miyazaki, Satoshi; Mobasher, Bahram; Moriya, Takashi; Nagao, Tohru; Ono, Yoshiaki; Ouchi, Massami; Petric, Andrea; Pych, Wojtek; Quimby, Robert; Saito, Tomoki; Salvato, Mara; Sanders, Dave; Scarlata, Claudia; Schinnerer, Eva; Scoville, Nick; Sheth, Kartik; Shimasaku, Kazuhiro; Silverman, John; Smolcic, Vernesa; Steinhardt, Charles; Strauss, Michael; Surace, Jason; Tanaka, Masaomi; Tanaka, Massayuki; Taniguchi, Yoshi; Teplitz, Harry; Toshida, Naoki; Wang, Wei-Hao; Urata, Yuji

    2013-10-01

    We propose 1650h to complete SPLASH, building a foundation for comprehensive investigations of the earliest stages of galaxy, AGN and large-scale structure formation on cosmologically important scales, providing deep mid-IR imaging for two major 1.8deg^2 fields (COSMOS and SXDS). These two fields have been the target of, and are scheduled for, unparalleled deep imaging in the optical, sub-mm and radio. The Spitzer data are essential for immediate science goals and the legacy of these unique equatorial fields. The major science enabled by the proposed Spitzer observations includes: the co-evolution of cosmic large scale structure and the assembly and growth of galaxies and AGN; understanding the relative importance of smooth gas accretion vs. mergers for galaxy growth in the early universe; probing re-ionization through Infrared Background Fluctuations; constraining the Initial Mass Function at high redshift, AGN activity in the early universe, and the physics of supernova through transient studies. None of these are possible with existing Spitzer surveys. The two fields proposed here will have unique, Hyper-Suprime-Cam (HSC) imaging (to ~27-28 magAB for broad bands across the 0.4-1.0um wavelength range) and science will be immediately enabled by Spitzer using pre-existing deep X-ray to radio multi-wavelength data, including: UV (Galex), X-ray (Chandra/XMM), optical (HST), near-infrared, mid-Infrared (Spitzer/Herschel), sub-mm, and radio. The COSMOS field is the primary deep field for the Nu-Star mission and both fields have been ranked as high priority deep-field targets for Euclid. These fields also have extensive spectroscopy with Keck (>50nt), Subaru-FMOS (>30nt), VLT (>1000h), and are the primary targets for the future Subaru Prime Focus Spectrograph (PFS) surveys. The legacy impact of these data will be enormous, and will provide a treasure trove of targets for JWST. This is part 1 (SXDS) of the awarded time.

  7. Readout for a large area neutron sensitive microchannel plate detector

    NASA Astrophysics Data System (ADS)

    Wang, Yiming; Yang, Yigang; Wang, Xuewu; Li, Yuanjing

    2015-06-01

    A neutron sensitive microchannel plate (MCP) detector was developed for neutron imaging on the beamline of a compact pulsed hadron source (CPHS). The detector was set up with a Wedge-and-Strip Anode (WSA) and a delay line anode readout to compare the spatial resolution and throughput with these two anodes. Tests show that the WSA readout is suitable for small area imaging with a spatial resolution of 200 μm with low energy X-rays in a 50 mm diameter MCP-WSA assembly. However, the spatial resolution deteriorated to ~2 mm in a 106 mm diameter MCP-WSA assembly because the noise caused by the parasitic capacitance is 10 times larger in the larger assembly than in the 50 mm diameter assembly. A 120 mm by 120 mm delay line anode was then used for the 106 mm MCP readout. The spatial resolution was evaluated for various voltages applied to the MCP V-stack, various readout voltages and various distances between the MCP V-stack rear face and the delay line. The delay line readout had resolutions of 65.6 μm in the x direction and 63.7 μm in the y direction and the throughput was greater than 600 kcps. The MCP was then used to acquire a neutron image of an USAF1951 Gd-mask.

  8. Complex vibration ultrasonic welding systems with large area welding tips.

    PubMed

    Tsujino, Jiromaru; Sano, Tsutomu; Ogata, Hayato; Tanaka, Soichi; Harada, Yoshiki

    2002-05-01

    Vibration and welding characteristics of complex vibration ultrasonic welding systems of 27 and 40 kHz were studied. Complex vibration systems, which have elliptical to circular or rectangular to square locus, are effective for ultrasonic welding of various specimens including the same and different metal specimens, and for direct welding of semiconductor tips and packaging of various electronic devices without solder. The complex vibration systems consist of a one-dimensional longitudinal-torsional vibration converter with slitted part, a stepped horn and a longitudinal vibration transducer as a driving source. The complex vibration welding tips of 27 and 40 kHz have enough area of 6-8 mm square for various welding specimens. Aluminum plate specimens of 0.3-1.0 mm thickness were successfully joined with weld strengths almost equal to aluminum specimen strength, and independent to the specimen direction. Required vibration amplitude of 40 kHz is smaller than that of 27 kHz. PMID:12159965

  9. Atmospheric SF6 near a large urban area

    NASA Astrophysics Data System (ADS)

    Ho, David T.; Schlosser, Peter

    2000-06-01

    Sulfur hexafluoride (SF6) has the potential to be a valuable transient tracer for dating of young ground water. However, near urban areas, there are typically numerous point sources of SF6 which have a significant impact on the temporal evolution of its atmospheric mixing ratio, thereby complicating its use as an age-dating tool. Here, we present and discuss a 12-month record of atmospheric SF6 from a location near New York City. The data were obtained by gas chromatographic analyses performed at intervals of approximately 10 minutes yielding about 40,000 data points for the time series. Nearly all measured SF6 values are in excess of remote Northern Hemisphere (NH) atmospheric mixing ratios. Temporal trends in the baseline data from LDEO indicate that atmospheric SF6 at LDEO decreased at a rate of 0.4 ppt yr-1 over the 12-month period. The SF6 data are compared to records of CFCs obtained during the same period. Whereas the CFCs show daily, weekly, and seasonal patterns of variability near New York City, the SF6 data exhibit only a daily cycle. The observed SF6 excesses are far greater than those found for CFCs during the same time period. This indicates that in order to use SF6 as an age dating tool of groundwater near source regions, its input function, i.e., its concentration in soil air above the groundwater table, needs to be defined explicitly.

  10. Large-Area Semiconducting Graphene Nanomesh Tailored by Interferometric Lithography

    PubMed Central

    Kazemi, Alireza; He, Xiang; Alaie, Seyedhamidreza; Ghasemi, Javad; Dawson, Noel Mayur; Cavallo, Francesca; Habteyes, Terefe G.; Brueck, Steven R. J.; Krishna, Sanjay

    2015-01-01

    Graphene nanostructures are attracting a great deal of interest because of newly emerging properties originating from quantum confinement effects. We report on using interferometric lithography to fabricate uniform, chip-scale, semiconducting graphene nanomesh (GNM) with sub-10 nm neck widths (smallest edge-to-edge distance between two nanoholes). This approach is based on fast, low-cost, and high-yield lithographic technologies and demonstrates the feasibility of cost-effective development of large-scale semiconducting graphene sheets and devices. The GNM is estimated to have a room temperature energy bandgap of ~30 meV. Raman studies showed that the G band of the GNM experiences a blue shift and broadening compared to pristine graphene, a change which was attributed to quantum confinement and localization effects. A single-layer GNM field effect transistor exhibited promising drive current of ~3.9 μA/μm and ON/OFF current ratios of ~35 at room temperature. The ON/OFF current ratio of the GNM-device displayed distinct temperature dependence with about 24-fold enhancement at 77 K. PMID:26126936

  11. Large-Area Semiconducting Graphene Nanomesh Tailored by Interferometric Lithography

    NASA Astrophysics Data System (ADS)

    Kazemi, Alireza; He, Xiang; Alaie, Seyedhamidreza; Ghasemi, Javad; Dawson, Noel Mayur; Cavallo, Francesca; Habteyes, Terefe G.; Brueck, Steven R. J.; Krishna, Sanjay

    2015-07-01

    Graphene nanostructures are attracting a great deal of interest because of newly emerging properties originating from quantum confinement effects. We report on using interferometric lithography to fabricate uniform, chip-scale, semiconducting graphene nanomesh (GNM) with sub-10 nm neck widths (smallest edge-to-edge distance between two nanoholes). This approach is based on fast, low-cost, and high-yield lithographic technologies and demonstrates the feasibility of cost-effective development of large-scale semiconducting graphene sheets and devices. The GNM is estimated to have a room temperature energy bandgap of ~30 meV. Raman studies showed that the G band of the GNM experiences a blue shift and broadening compared to pristine graphene, a change which was attributed to quantum confinement and localization effects. A single-layer GNM field effect transistor exhibited promising drive current of ~3.9 μA/μm and ON/OFF current ratios of ~35 at room temperature. The ON/OFF current ratio of the GNM-device displayed distinct temperature dependence with about 24-fold enhancement at 77 K.

  12. Performance model for large area solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Klotz, Dino; Schmidt, Jan Philipp; Weber, André; Ivers-Tiffée, Ellen

    2014-08-01

    A parameter set obtained from a 1 cm2 size electrode cell is used to develop and calibrate a one-dimensional spatially resolved model. It is demonstrated that this performance model precalculates the evolving operating parameters along the gas channel of a large-sized cell. Input parameters are: (i) number of discretization elements N, accounting for anodic gas conversion, (ii) anodic gas flow rate and composition and (iv) operating voltage. The model calculations based on data from the 1 cm2 cell are scaled to be equivalent to a larger cell with 16 cm2 electrode size which is used to validate the performance model. The current/voltage characteristics can be predicted very accurately, even when anodic gas flow rates vary by as much as a factor of four. The performance model presented herein simulates the total overvoltage and does so in a broad range of operation conditions. This is done with an accuracy of the simulated current better than 6.1% for UOP = 0.85 V, 3.8% for UOP = 0.8 V and 3.7% for UOP = 0.75 V. It is hoped that these equations will form the basis of a greater model, capable of predicting all the conditions found throughout any industrial stack.

  13. The Incidence of Dwarf Novae in Large Area Transient Searches

    NASA Astrophysics Data System (ADS)

    Rau, A.; Schwarz, R.; Kulkarni, S. R.; Ofek, E. O.; Kasliwal, M. M.; Brinkworth, C.; Cenko, S. B.; Lipkin, Y.; Soderberg, A. M.

    2007-07-01

    Understanding and quantifying the contribution of known classes of transient and variable sources is an important lesson to be learned from the manifold of precursor programs of the near-future large synoptic sky survey programs such as SkyMapper, Pan-STARRS, and LSST. With this goal in mind, we undertook photometric and spectroscopic follow-up observations of four recently reported unidentified transients. For two sources, WFI J132813.7-214237 and WFI J161953.3+031909, we show that unfortunate coincidences led to their previous designation as transients. While the former is now interpreted as the spatial coincidence of a solar system object with a faint background star, the latter is merely a cataclysmic variable unfortunately caught in and out of eclipse. The third candidate, ROTSE3 J160213.1-021311.7, is identified as an SU UMa type dwarf nova with quiescent brightness of R~22.7 and an outburst amplitude of ~5 mag. The fourth event, SDSS-SN 15207, similarly shows evidence for a dwarf nova origin. Our main conclusion is that cataclysmic variables in their various avatars will contribute moderately to the population of transient objects.

  14. Quantum transport in strongly disordered crystals: Electrical conductivity with large negative vertex corrections

    NASA Astrophysics Data System (ADS)

    Janiš, Václav; Pokorný, Vladislav

    2012-12-01

    We propose a renormalization scheme of the Kubo formula for the electrical conductivity with multiple backscatterings contributing to the electron-hole irreducible vertex derived from the asymptotic limit to high spatial dimensions. We use this vertex to represent the two-particle Green function via a symmetrized Bethe-Salpeter equation in momentum space. We further utilize the dominance of a pole in the irreducible vertex to an approximate diagonalization of the Bethe-Salpeter equation and a non-perturbative representation of the electron-hole correlation function. The latter function is then used to derive a compact representation for the electrical conductivity at zero temperature without the necessity to evaluate separately the Drude term and vertex corrections. The electrical conductivity calculated in this way remains nonnegative also in the strongly disordered regime where the localization effects become significant and the negative vertex corrections in the standard Kubo formula overweight the Drude term.

  15. A new large area lanthanum hexaboride plasma source

    SciTech Connect

    Cooper, C. M.; Gekelman, W.; Pribyl, P.; Lucky, Z.

    2010-08-15

    A new 18x18 cm{sup 2} active area lanthanum hexaboride (LaB{sub 6}) plasma source for use in a dc discharge has been developed at UCLA. The cathode consists of four tiled LaB{sub 6} pieces indirectly heated to electron emission (1750 deg. C) by a graphite heater. A molybdenum mesh anode 33 cm in front of the LaB{sub 6} accelerates the electrons, ionizing a fill gas to create a 20x20 cm{sup 2} nearly square plasma. The source is run in pulsed operation with the anode biased up to +400 V dc with respect to the cathode for up to 100 ms at a 1 Hz repetition rate. Both the cathode and anode ''float'' electrically with respect to the chamber walls. The source is placed in a toroidal chamber 2 m wide and 3 m tall with a major radius of 5 m. Toroidal and vertical magnetic fields confine the current-free plasma which follows the field in a helix. The plasma starts on the bottom of the machine and spirals around it up to four times (120 m) and can be configured to terminate either on the top wall or on the neutral gas itself. The source typically operates with a discharge current up to 250 A in helium making plasmas with T{sub e}<30 eV, T{sub i}<16 eV, and n{sub e}<3x10{sup 13} cm{sup -3} in a background field of 100 G

  16. Negative blood oxygenation level dependent homunculus and somatotopic information in primary motor cortex and supplementary motor area.

    PubMed

    Zeharia, Noa; Hertz, Uri; Flash, Tamar; Amedi, Amir

    2012-11-01

    A crucial attribute in movement encoding is an adequate balance between suppression of unwanted muscles and activation of required ones. We studied movement encoding across the primary motor cortex (M1) and supplementary motor area (SMA) by inspecting the positive and negative blood oxygenation level-dependent (BOLD) signals in these regions. Using periodic and event-related experiments incorporating the bilateral/axial movements of 20 body parts, we report detailed mototopic imaging maps in M1 and SMA. These maps were obtained using phase-locked analysis. In addition to the positive BOLD, significant negative BOLD was detected in M1 but not in the SMA. The negative BOLD spatial pattern was neither located at the ipsilateral somatotopic location nor randomly distributed. Rather, it was organized somatotopically across the entire homunculus and inversely to the positive BOLD, creating a negative BOLD homunculus. The neuronal source of negative BOLD is unclear. M1 provides a unique system to test whether the origin of negative BOLD is neuronal, because different arteries supply blood to different regions in the homunculus, ruling out blood-stealing explanations. Finally, multivoxel pattern analysis showed that positive BOLD in M1 and SMA and negative BOLD in M1 contain somatotopic information, enabling prediction of the moving body part from inside and outside its somatotopic location. We suggest that the neuronal processes underlying negative BOLD participate in somatotopic encoding in M1 but not in the SMA. This dissociation may emerge because of differences in the activity of these motor areas associated with movement suppression. PMID:23086164

  17. A large area, silicon photomultiplier-based PET detector module

    PubMed Central

    Raylman, RR; Stolin, A; Majewski, S; Proffitt, J

    2013-01-01

    The introduction of silicon photomultipliers (SiPM) has facilitated construction of compact, efficient and magnetic field-hardened positron emission tomography (PET) scanners. To take full advantage of these devices, methods for using them to produce large field-of-view PET scanners are needed. In this investigation, we explored techniques to combine two SiPM arrays to form the building block for a small animal PET scanner. The module consists of a 26 × 58 array of 1.5 × 1.5mm2 LYSO elements (spanning 41 × 91mm2) coupled to two SensL SiPM arrays. The SiPMs were read out with new multiplexing electronics developed for this project. To facilitate calculation of event position with multiple SiPM arrays it was necessary to spread scintillation light amongst a number of elements with a small light guide. This method was successful in permitting identification of all detector elements, even at the seam between two SiPM arrays. Since the performance of SiPMs is enhanced by cooling, the detector module was fitted with a cooling jacket, which allowed the temperature of the device and electronics to be controlled. Testing demonstrated that the peak-to-valley contrast ratio of the light detected from the scintillation array was increased by ∼45% when the temperature was reduced from 28 °C to 16 °C. Energy resolution for 511 keV photons improved slightly from 18.8% at 28 °C to 17.8% at 16 °C. Finally, the coincidence timing resolution of the module was found to be insufficient for time-of-flight applications (∼2100 ps at 14 °C). The first use of these new modules will be in the construction of a small animal PET scanner to be integrated with a 3T clinical magnetic resonance imaging scanner. PMID:24319305

  18. A large area, silicon photomultiplier-based PET detector module

    NASA Astrophysics Data System (ADS)

    Raylman, R. R.; Stolin, A.; Majewski, S.; Proffitt, J.

    2014-01-01

    The introduction of silicon photomultipliers (SiPM) has facilitated construction of compact, efficient and magnetic field-hardened positron emission tomography (PET) scanners. To take full advantage of these devices, methods for using them to produce large field-of-view PET scanners are needed. In this investigation, we explored techniques to combine two SiPM arrays to form the building block for a small animal PET scanner. The module consists of a 26×58 array of 1.5×1.5 mm2 LYSO elements (spanning 41×91 mm2) coupled to two SensL SiPM arrays. The SiPMs were read out with new multiplexing electronics developed for this project. To facilitate calculation of event position with multiple SiPM arrays it was necessary to spread scintillation light amongst a number of elements with a small light guide. This method was successful in permitting identification of all detector elements, even at the seam between two SiPM arrays. Since the performance of SiPMs is enhanced by cooling, the detector module was fitted with a cooling jacket, which allowed the temperature of the device and electronics to be controlled. Testing demonstrated that the peak-to-valley contrast ratio of the light detected from the scintillation array was increased by ~45% when the temperature was reduced from 28 °C to 16 °C. Energy resolution for 511 keV photons improved slightly from 18.8% at 28 °C to 17.8% at 16 °C. Finally, the coincidence timing resolution of the module was found to be insufficient for time-of-flight applications (~2100 ps at 14 °C). The first use of these new modules will be in the construction of a small animal PET scanner to be integrated with a 3 T clinical magnetic resonance imaging scanner.

  19. Lower ionosphere large positive and negative ions are still puzzling: A potential role in ion induced aerosol formation

    NASA Astrophysics Data System (ADS)

    Arnold, Frank

    2016-04-01

    Inspired by greatly improved possibilities in future rocket borne high mass resolution ion mass spectrometry, previous pioneering rocket borne ion-mass spectrometer measurements, made by our MPIK-Heidelberg research group in the lower ionosphere, are revisited and reanalyzed. Here the focus is placed upon puzzling observations of lower ionosphere large positive and large negative ions. These have a role in lower ionosphere free electron removal. They also have a potential role in lower ionosphere aerosol and eventually even cloud formation. Measurements and model simulations are presented.

  20. Negative functional MRI response correlates with decreases in neuronal activity in monkey visual area V1.

    PubMed

    Shmuel, Amir; Augath, Mark; Oeltermann, Axel; Logothetis, Nikos K

    2006-04-01

    Most functional brain imaging studies use task-induced hemodynamic responses to infer underlying changes in neuronal activity. In addition to increases in cerebral blood flow and blood oxygenation level-dependent (BOLD) signals, sustained negative responses are pervasive in functional imaging. The origin of negative responses and their relationship to neural activity remain poorly understood. Through simultaneous functional magnetic resonance imaging and electrophysiological recording, we demonstrate a negative BOLD response (NBR) beyond the stimulated regions of visual cortex, associated with local decreases in neuronal activity below spontaneous activity, detected 7.15 +/- 3.14 mm away from the closest positively responding region in V1. Trial-by-trial amplitude fluctuations revealed tight coupling between the NBR and neuronal activity decreases. The NBR was associated with comparable decreases in local field potentials and multiunit activity. Our findings indicate that a significant component of the NBR originates in neuronal activity decreases. PMID:16547508

  1. CD30-Positive Anaplastic Lymphoma Kinase-Negative Systemic Anaplastic Large-Cell Lymphoma in a 9-Year-Old Boy

    PubMed Central

    Kim, Jeong Eun; Oh, Eui Hyun; Ro, Young Suck

    2016-01-01

    Anaplastic large-cell lymphoma (ALCL) is a CD30-positive T-cell/null-cell lymphoma that is clinically classified into either primary cutaneous ALCL or systemic ALCL (S-ALCL) sub-types. Because 90% of childhood S-ALCL cases are anaplastic lymphoma kinase (ALK)-positive, there is a lack of data on ALK-negative S-ALCL cases among pediatric patients. Herein, we report a rare case of ALK-negative S-ALCL in a 9-year-old Korean boy who initially presented with itchy erythematous maculopapules and an erosive nodule on the trunk area. We emphasize the need of high index of suspicion of an underlying malignant disease in the presence of refractory eczematous lesions. PMID:27274637

  2. CD30-Positive Anaplastic Lymphoma Kinase-Negative Systemic Anaplastic Large-Cell Lymphoma in a 9-Year-Old Boy.

    PubMed

    Kim, Jeong Eun; Oh, Eui Hyun; Ro, Young Suck; Ko, Joo Yeon

    2016-06-01

    Anaplastic large-cell lymphoma (ALCL) is a CD30-positive T-cell/null-cell lymphoma that is clinically classified into either primary cutaneous ALCL or systemic ALCL (S-ALCL) sub-types. Because 90% of childhood S-ALCL cases are anaplastic lymphoma kinase (ALK)-positive, there is a lack of data on ALK-negative S-ALCL cases among pediatric patients. Herein, we report a rare case of ALK-negative S-ALCL in a 9-year-old Korean boy who initially presented with itchy erythematous maculopapules and an erosive nodule on the trunk area. We emphasize the need of high index of suspicion of an underlying malignant disease in the presence of refractory eczematous lesions. PMID:27274637

  3. Large unsaturated positive and negative magnetoresistance in Weyl semimetal TaP

    NASA Astrophysics Data System (ADS)

    Du, JianHua; Wang, HangDong; Chen, Qin; Mao, QianHui; Khan, Rajwali; Xu, BinJie; Zhou, YuXing; Zhang, YanNan; Yang, JinHu; Chen, Bin; Feng, ChunMu; Fang, MingHu

    2016-05-01

    After successfully growing single-crystal TaP, we measured its longitudinal resistivity ( ρ xx ) and Hall resistivity ( ρ yx ) at magnetic fields up to 9 T in the temperature range of 2-300 K. At 8 T, the magnetoresistance (MR) reached 3.28 × 105% at 2 K, 176% at 300 K. Neither value appeared saturated. We confirmed that TaP is a hole-electron compensated semimetal with a low carrier concentration and high hole mobility of μ h=3.71 × 105 cm2/V s, and found that a magnetic-field-induced metal-insulator transition occurs at room temperature. Remarkably, because a magnetic field ( H) was applied in parallel to the electric field ( E), a negative MR due to a chiral anomaly was observed and reached -3000% at 9 T without any sign of saturation, either, which is in contrast to other Weyl semimetals (WSMs). The analysis of the Shubnikov-de Haas (SdH) oscillations superimposed on the MR revealed that a nontrivial Berry's phase with a strong offset of 0.3958, which is the characteristic feature of charge carriers enclosing a Weyl node. These results indicate that TaP is a promising candidate not only for revealing fundamental physics of the WSM state but also for some novel applications.

  4. Large-scale patterns of turnover and Basal area change in Andean forests.

    PubMed

    Báez, Selene; Malizia, Agustina; Carilla, Julieta; Blundo, Cecilia; Aguilar, Manuel; Aguirre, Nikolay; Aquirre, Zhofre; Álvarez, Esteban; Cuesta, Francisco; Duque, Álvaro; Farfán-Ríos, William; García-Cabrera, Karina; Grau, Ricardo; Homeier, Jürgen; Linares-Palomino, Reynaldo; Malizia, Lucio R; Cruz, Omar Melo; Osinaga, Oriana; Phillips, Oliver L; Reynel, Carlos; Silman, Miles R; Feeley, Kenneth J

    2015-01-01

    General patterns of forest dynamics and productivity in the Andes Mountains are poorly characterized. Here we present the first large-scale study of Andean forest dynamics using a set of 63 permanent forest plots assembled over the past two decades. In the North-Central Andes tree turnover (mortality and recruitment) and tree growth declined with increasing elevation and decreasing temperature. In addition, basal area increased in Lower Montane Moist Forests but did not change in Higher Montane Humid Forests. However, at higher elevations the lack of net basal area change and excess of mortality over recruitment suggests negative environmental impacts. In North-Western Argentina, forest dynamics appear to be influenced by land use history in addition to environmental variation. Taken together, our results indicate that combinations of abiotic and biotic factors that vary across elevation gradients are important determinants of tree turnover and productivity in the Andes. More extensive and longer-term monitoring and analyses of forest dynamics in permanent plots will be necessary to understand how demographic processes and woody biomass are responding to changing environmental conditions along elevation gradients through this century. PMID:25973977

  5. Large-Scale Patterns of Turnover and Basal Area Change in Andean Forests

    PubMed Central

    Blundo, Cecilia; Aguilar, Manuel; Aguirre, Nikolay; Aquirre, Zhofre; Álvarez, Esteban; Cuesta, Francisco; Farfán-Ríos, William; García-Cabrera, Karina; Grau, Ricardo; Linares-Palomino, Reynaldo; Malizia, Lucio R.; Cruz, Omar Melo; Osinaga, Oriana; Reynel, Carlos; Silman, Miles R.

    2015-01-01

    General patterns of forest dynamics and productivity in the Andes Mountains are poorly characterized. Here we present the first large-scale study of Andean forest dynamics using a set of 63 permanent forest plots assembled over the past two decades. In the North-Central Andes tree turnover (mortality and recruitment) and tree growth declined with increasing elevation and decreasing temperature. In addition, basal area increased in Lower Montane Moist Forests but did not change in Higher Montane Humid Forests. However, at higher elevations the lack of net basal area change and excess of mortality over recruitment suggests negative environmental impacts. In North-Western Argentina, forest dynamics appear to be influenced by land use history in addition to environmental variation. Taken together, our results indicate that combinations of abiotic and biotic factors that vary across elevation gradients are important determinants of tree turnover and productivity in the Andes. More extensive and longer-term monitoring and analyses of forest dynamics in permanent plots will be necessary to understand how demographic processes and woody biomass are responding to changing environmental conditions along elevation gradients through this century. PMID:25973977

  6. Nonzero-temperature entanglement negativity of quantum spin models: Area law, linked cluster expansions, and sudden death.

    PubMed

    Sherman, Nicholas E; Devakul, Trithep; Hastings, Matthew B; Singh, Rajiv R P

    2016-02-01

    We show that the bipartite logarithmic entanglement negativity (EN) of quantum spin models obeys an area law at all nonzero temperatures. We develop numerical linked cluster (NLC) expansions for the "area-law" logarithmic entanglement negativity as a function of temperature and other parameters. For one-dimensional models the results of NLC are compared with exact diagonalization on finite systems and are found to agree very well. The NLC results are also obtained for two dimensional XXZ and transverse field Ising models. In all cases, we find a sudden onset (or sudden death) of negativity at a finite temperature above which the negativity is zero. We use perturbation theory to develop a physical picture for this sudden onset (or sudden death). The onset of EN or its magnitude are insensitive to classical finite-temperature phase transitions, supporting the argument for absence of any role of quantum mechanics at such transitions. On approach to a quantum critical point at T=0, negativity shows critical scaling in size and temperature. PMID:26986309

  7. Action-related semantic content and negation polarity modulate motor areas during sentence reading: an event-related desynchronization study.

    PubMed

    Alemanno, F; Houdayer, E; Cursi, M; Velikova, S; Tettamanti, M; Comi, G; Cappa, S F; Leocani, L

    2012-11-12

    Our study evaluated motor cortex involvement during silent reading of sentences referring to hand actions. We aimed at defining whether sentential polarity (affirmative vs. negative) would modulate motor cortex activation using the event-related desynchronization (ERD) analysis of the mu rhythm. Eleven healthy volunteers performed a reading task involving 160 sentences (80 affirmative: 40 hand-related, 40 abstract; 80 negative: 40 hand-related, 40 abstract). After reading each sentence, subjects had to decide whether the verb was high or low frequency in Italian. Electroencephalographic (EEG) activity was recorded with 32 surface electrodes and mu ERD analyses were performed for each subject. Hand-action related sentences induced a greater mu ERD over the left premotor and motor hand areas compared to abstract sentences. Mu ERD was greater and temporally delayed when the hand-related verbs were presented in the negative versus affirmative form. As predicted by the "embodied semantic" theory of language understanding, motor areas were activated during sentences referring to hand actions. In addition, motor cortex activation was larger for negative than affirmative motor sentences, a finding compatible with the hypothesis that comprehension is more demanding in the specific case of motor content negation. PMID:23010314

  8. Nonzero-temperature entanglement negativity of quantum spin models: Area law, linked cluster expansions, and sudden death

    NASA Astrophysics Data System (ADS)

    Sherman, Nicholas E.; Devakul, Trithep; Hastings, Matthew B.; Singh, Rajiv R. P.

    2016-02-01

    We show that the bipartite logarithmic entanglement negativity (EN) of quantum spin models obeys an area law at all nonzero temperatures. We develop numerical linked cluster (NLC) expansions for the "area-law" logarithmic entanglement negativity as a function of temperature and other parameters. For one-dimensional models the results of NLC are compared with exact diagonalization on finite systems and are found to agree very well. The NLC results are also obtained for two dimensional X X Z and transverse field Ising models. In all cases, we find a sudden onset (or sudden death) of negativity at a finite temperature above which the negativity is zero. We use perturbation theory to develop a physical picture for this sudden onset (or sudden death). The onset of EN or its magnitude are insensitive to classical finite-temperature phase transitions, supporting the argument for absence of any role of quantum mechanics at such transitions. On approach to a quantum critical point at T =0 , negativity shows critical scaling in size and temperature.

  9. Crop identification and area estimation over large geographic areas using LANDSAT MSS data

    NASA Technical Reports Server (NTRS)

    Bauer, M. E. (Principal Investigator)

    1977-01-01

    The author has identified the following significant results. LANDSAT MSS data was adequate to accurately identify wheat in Kansas; corn and soybean estimates in Indiana were less accurate. Computer-aided analysis techniques were effectively used to extract crop identification information from LANDSAT data. Systematic sampling of entire counties made possible by computer classification methods resulted in very precise area estimates at county, district, and state levels. Training statistics were successfully extended from one county to other counties having similar crops and soils if the training areas sampled the total variation of the area to be classified.

  10. Large negative magnetoresistance in reactive sputtered polycrystalline GdN{sub x} films

    SciTech Connect

    Mi, W. B.; Duan, X. F.; Zhang, X. J.; Bai, H. L.; Guo, Z. B.

    2013-06-03

    Polycrystalline ferromagnetic GdN{sub x} films were fabricated at different N{sub 2} flow rates (f{sub N2}) to modify N-vacancy concentration so as to study its influence on electrotransport. Metal-semiconductor transition appears at Curie temperature (T{sub C}) of {approx}40 K. Temperature-dependent magnetoresistance (MR) shows a peak at T{sub C}. The films at f{sub N2} = 5, 10, 15, and 20 sccm show MR of -38%, -42%, -46%, and -86% at 5 K and 50 kOe, respectively. Above 15 K, MR is from colossal MR and from both colossal and tunneling MR below 15 K. The enhanced MR at f{sub N2} = 20 sccm is attributed to large spin polarization of half-metallicity in GdN{sub x} with low N vacancies.

  11. Approach to the Triple Negative Breast Cancer in New Drugs Area

    PubMed Central

    Mirzania, Mehrzad

    2016-01-01

    Triple negative breast cancers (TNBCs) are associated with aggressive course, higher rates of visceral and central nervous system metastases and lower survival rate than hormone receptor positive. Once metastasis has occurred, a median survival was approximately one year. Currently, chemotherapy in TNBC is similar to other HER2- negative breast cancers but in the near future, it will revolutionize. TNBCs are quite heterogeneous based on biomarkers and genetic variations. The series of new drugs have been tried; in this article, platinum, anti-epigenetic drugs, PARP inhibitors, epidermal growth factor receptor inhibitor, Src family kinase inhibitor, anti androgen, glycoprotein Non-metastatic melanoma B (gpNMB) antibody, LHRH conjugated to cytotoxic drugs and inhibition of the PI3K/AKT/mTOR pathway will be explained. What is the optimal therapy for TNBC patients? It is still not clear but it seems that the road map according to biological and genetic markers is taking shape. PMID:27252813

  12. Sub-100nm gold nanomatryoshkas improve photo-thermal therapy efficacy in large and highly aggressive triple negative breast tumors.

    PubMed

    Ayala-Orozco, Ciceron; Urban, Cordula; Bishnoi, Sandra; Urban, Alexander; Charron, Heather; Mitchell, Tamika; Shea, Martin; Nanda, Sarmistha; Schiff, Rachel; Halas, Naomi; Joshi, Amit

    2014-10-10

    There is an unmet need for efficient near-infrared photothermal transducers for the treatment of highly aggressive cancers and large tumors where the penetration of light can be substantially reduced, and the intra-tumoral nanoparticle transport is restricted due to the presence of hypoxic or necrotic regions. We report the performance advantages obtained by sub 100nm gold nanomatryushkas, comprising concentric gold-silica-gold layers compared to conventional ~150nm silica core gold nanoshells for photothermal therapy of triple negative breast cancer. We demonstrate that a 33% reduction in silica-core-gold-shell nanoparticle size, while retaining near-infrared plasmon resonance, and keeping the nanoparticle surface charge constant, results in a four to five fold tumor accumulation of nanoparticles following equal dose of injected gold for both sizes. The survival time of mice bearing large (>1000mm(3)) and highly aggressive triple negative breast tumors is doubled for the nanomatryushka treatment group under identical photo-thermal therapy conditions. The higher absorption cross-section of a nanomatryoshka results in a higher efficiency of photonic to thermal energy conversion and coupled with 4-5× accumulation within large tumors results in superior therapy efficacy. PMID:25051221

  13. Sub-100 nm Gold Nanomatryoshkas Improve Photo-thermal Therapy Efficacy in Large and Highly Aggressive Triple Negative Breast Tumors

    PubMed Central

    Bishnoi, Sandra; Urban, Alexander; Charron, Heather; Mitchell, Tamika; Shea, Martin; Nanda, Sarmistha; Schiff, Rachel; Halas, Naomi; Joshi, Amit

    2014-01-01

    There is an unmet need for efficient near-infrared photothermal transducers for the treatment of highly aggressive cancers and large tumors where the penetration of light can be substantially reduced, and the intra-tumoral nanoparticle transport is restricted due to the presence of hypoxic or nectrotic regions. We report the performance advantages obtained by sub 100 nm gold nanomatryushkas, comprising of concentric gold-silica-gold layers compared to conventional ~150 nm silica core gold nanoshells for photothermal therapy of triple negative breast cancer. We demonstrate that a 33% reduction in silica-core-gold-shell nanoparticle size, while retaining near-infrared plasmon resonance, and keeping the nanoparticle surface charge constant, results in a four to five fold tumor accumulation of nanoparticles following equal dose of injected gold for both sizes. The survival time of mice bearing large (>1000 mm3) and highly aggressive triple negative breast tumors is doubled for the nanomatryushka treatment group under identical photo-thermal therapy conditions. The higher absorption cross-section of a nanomatryoshka results in a higher efficiency of photonic to thermal energy conversion and coupled with 4-5X accumulation within large tumors results in superior therapy efficacy. PMID:25051221

  14. Improved time response for large area microchannel plate photomultiplier tubes in fusion diagnostics

    SciTech Connect

    Milnes, J. S. Conneely, T. M.; Howorth, J.; Horsfield, C. J.

    2014-11-15

    Fusion diagnostics that utilise high speed scintillators often need to capture a large area of light with a high degree of time accuracy. Microchannel plate (MCP) photomultiplier tubes (PMTs) are recognised as the leading device for capturing fast optical signals. However, when manufactured in their traditional proximity focused construction, the time response performance is reduced as the active area increases. This is due to two main factors: the capacitance of a large anode and the difficulty of obtaining small pore MCPs with a large area. Collaboration between Photek and AWE has produced prototype devices that combine the excellent time response of small area MCP-PMTs with a large active area by replacing the traditional proximity-gap front section with an electro-optically focused photocathode to MCP. We present results from both single and double MCP devices with a 40 mm diameter active area and show simulations for the 100 mm device being built this year.

  15. Improved time response for large area microchannel plate photomultiplier tubes in fusion diagnostics

    NASA Astrophysics Data System (ADS)

    Milnes, J. S.; Horsfield, C. J.; Conneely, T. M.; Howorth, J.

    2014-11-01

    Fusion diagnostics that utilise high speed scintillators often need to capture a large area of light with a high degree of time accuracy. Microchannel plate (MCP) photomultiplier tubes (PMTs) are recognised as the leading device for capturing fast optical signals. However, when manufactured in their traditional proximity focused construction, the time response performance is reduced as the active area increases. This is due to two main factors: the capacitance of a large anode and the difficulty of obtaining small pore MCPs with a large area. Collaboration between Photek and AWE has produced prototype devices that combine the excellent time response of small area MCP-PMTs with a large active area by replacing the traditional proximity-gap front section with an electro-optically focused photocathode to MCP. We present results from both single and double MCP devices with a 40 mm diameter active area and show simulations for the 100 mm device being built this year.

  16. Improved time response for large area microchannel plate photomultiplier tubes in fusion diagnostics.

    PubMed

    Milnes, J S; Horsfield, C J; Conneely, T M; Howorth, J

    2014-11-01

    Fusion diagnostics that utilise high speed scintillators often need to capture a large area of light with a high degree of time accuracy. Microchannel plate (MCP) photomultiplier tubes (PMTs) are recognised as the leading device for capturing fast optical signals. However, when manufactured in their traditional proximity focused construction, the time response performance is reduced as the active area increases. This is due to two main factors: the capacitance of a large anode and the difficulty of obtaining small pore MCPs with a large area. Collaboration between Photek and AWE has produced prototype devices that combine the excellent time response of small area MCP-PMTs with a large active area by replacing the traditional proximity-gap front section with an electro-optically focused photocathode to MCP. We present results from both single and double MCP devices with a 40 mm diameter active area and show simulations for the 100 mm device being built this year. PMID:25430347

  17. A large family of antivirulence regulators modulates the effects of transcriptional activators in Gram-negative pathogenic bacteria.

    PubMed

    Santiago, Araceli E; Ruiz-Perez, Fernando; Jo, Noah Y; Vijayakumar, Vidhya; Gong, Mei Q; Nataro, James P

    2014-05-01

    We have reported that transcription of a hypothetical small open reading frame (orf60) in enteroaggregative E. coli (EAEC) strain 042 is impaired after mutation of aggR, which encodes a global virulence activator. We have also reported that the cryptic orf60 locus was linked to protection against EAEC diarrhea in two epidemiologic studies. Here, we report that the orf60 product acts as a negative regulator of aggR itself. The orf60 protein product lacks homology to known repressors, but displays 44-100% similarity to at least fifty previously undescribed small (<10 kDa) hypothetical proteins found in many gram negative pathogen genomes. Expression of orf60 homologs from enterotoxigenic E. coli (ETEC) repressed the expression of the AraC-transcriptional ETEC regulator CfaD/Rns and its regulon in ETEC strain H10407. Complementation in trans of EAEC 042orf60 by orf60 homologs from ETEC and the mouse pathogen Citrobacter rodentium resulted in dramatic suppression of aggR. A C. rodentium orf60 homolog mutant showed increased levels of activator RegA and increased colonization of the adult mouse. We propose the name Aar (AggR-activated regulator) for the clinically and epidemiologically important orf60 product in EAEC, and postulate the existence of a large family of homologs among pathogenic Enterobacteriaceae and Pasteurellaceae. We propose the name ANR (AraC Negative Regulators) for this family. PMID:24875828

  18. A Large Family of Antivirulence Regulators Modulates the Effects of Transcriptional Activators in Gram-negative Pathogenic Bacteria

    PubMed Central

    Santiago, Araceli E.; Ruiz-Perez, Fernando; Jo, Noah Y.; Vijayakumar, Vidhya; Gong, Mei Q.; Nataro, James P.

    2014-01-01

    We have reported that transcription of a hypothetical small open reading frame (orf60) in enteroaggregative E. coli (EAEC) strain 042 is impaired after mutation of aggR, which encodes a global virulence activator. We have also reported that the cryptic orf60 locus was linked to protection against EAEC diarrhea in two epidemiologic studies. Here, we report that the orf60 product acts as a negative regulator of aggR itself. The orf60 protein product lacks homology to known repressors, but displays 44–100% similarity to at least fifty previously undescribed small (<10 kDa) hypothetical proteins found in many gram negative pathogen genomes. Expression of orf60 homologs from enterotoxigenic E. coli (ETEC) repressed the expression of the AraC-transcriptional ETEC regulator CfaD/Rns and its regulon in ETEC strain H10407. Complementation in trans of EAEC 042orf60 by orf60 homologs from ETEC and the mouse pathogen Citrobacter rodentium resulted in dramatic suppression of aggR. A C. rodentium orf60 homolog mutant showed increased levels of activator RegA and increased colonization of the adult mouse. We propose the name Aar (AggR-activated regulator) for the clinically and epidemiologically important orf60 product in EAEC, and postulate the existence of a large family of homologs among pathogenic Enterobacteriaceae and Pasteurellaceae. We propose the name ANR (AraC Negative Regulators) for this family. PMID:24875828

  19. ANCA-negative eosinophilic granulomatosis with polyangitis (EGPA) manifesting as a large intracardiac thrombus and glomerulonephritis with angionecrosis.

    PubMed

    Saito, Yuichi; Okada, Sho; Funabashi, Nobusada; Kobayashi, Yoshio

    2016-01-01

    A 59-year-old woman with a history of bronchial asthma presented with a prolonged fever and eosinophilia. There was transient proteinuria and troponin level was elevated. Antineutrophil cytoplasmic antibody was negative and she did not fulfil criteria for eosinophilic granulomatosis with polyangitis (EGPA). Echocardiography showed a large apical mass in the left ventricle, but there was no systolic dysfunction, local asynergy or ventricular remodelling. On MRI, apical mass was compatible with a thrombus and endocardial region was diffusely damaged. Loeffler endocarditis-like cardiac manifestation led to meticulous examination, which found no aetiology for eosinophilia. Finally, renal biopsy revealed eosinophil infiltration and glomerular angionecrosis, confirming as EGPA. This case highlights the isolated large cardiac thrombus as a rare presenting sign for EGPA and underscores current complicated strategy to diagnose EGPA. Of note, this clinical challenge was mostly caused by inchoate comprehension of hypereosinophilia-related disorders. PMID:27591039

  20. Highly Flexible and High-Performance Complementary Inverters of Large-Area Transition Metal Dichalcogenide Monolayers.

    PubMed

    Pu, Jiang; Funahashi, Kazuma; Chen, Chang-Hsiao; Li, Ming-Yang; Li, Lain-Jong; Takenobu, Taishi

    2016-06-01

    Complementary inverters constructed from large-area monolayers of WSe2 and MoS2 achieve excellent logic swings and yield an extremely high gain, large total noise margin, low power consumption, and good switching speed. Moreover, the WSe2 complementary-like inverters built on plastic substrates exhibit high mechanical stability. The results provide a path toward large-area flexible electronics. PMID:27007295

  1. Antibacterial activity of large-area monolayer graphene film manipulated by charge transfer

    PubMed Central

    Li, Jinhua; Wang, Gang; Zhu, Hongqin; Zhang, Miao; Zheng, Xiaohu; Di, Zengfeng; Liu, Xuanyong; Wang, Xi

    2014-01-01

    Graphene has attracted increasing attention for potential applications in biotechnology due to its excellent electronic property and biocompatibility. Here we use both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) to investigate the antibacterial actions of large-area monolayer graphene film on conductor Cu, semiconductor Ge and insulator SiO2. The results show that the graphene films on Cu and Ge can surprisingly inhibit the growth of both bacteria, especially the former. However, the proliferation of both bacteria cannot be significantly restricted by the graphene film on SiO2. The morphology of S. aureus and E. coli on graphene films further confirms that the direct contact of both bacteria with graphene on Cu and Ge can cause membrane damage and destroy membrane integrity, while no evident membrane destruction is induced by graphene on SiO2. From the viewpoint of charge transfer, a plausible mechanism is proposed here to explain this phenomenon. This study may provide new insights for the better understanding of antibacterial actions of graphene film and for the better designing of graphene-based antibiotics or other biomedical applications. PMID:24619247

  2. Antibacterial activity of large-area monolayer graphene film manipulated by charge transfer

    NASA Astrophysics Data System (ADS)

    Li, Jinhua; Wang, Gang; Zhu, Hongqin; Zhang, Miao; Zheng, Xiaohu; di, Zengfeng; Liu, Xuanyong; Wang, Xi

    2014-03-01

    Graphene has attracted increasing attention for potential applications in biotechnology due to its excellent electronic property and biocompatibility. Here we use both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) to investigate the antibacterial actions of large-area monolayer graphene film on conductor Cu, semiconductor Ge and insulator SiO2. The results show that the graphene films on Cu and Ge can surprisingly inhibit the growth of both bacteria, especially the former. However, the proliferation of both bacteria cannot be significantly restricted by the graphene film on SiO2. The morphology of S. aureus and E. coli on graphene films further confirms that the direct contact of both bacteria with graphene on Cu and Ge can cause membrane damage and destroy membrane integrity, while no evident membrane destruction is induced by graphene on SiO2. From the viewpoint of charge transfer, a plausible mechanism is proposed here to explain this phenomenon. This study may provide new insights for the better understanding of antibacterial actions of graphene film and for the better designing of graphene-based antibiotics or other biomedical applications.

  3. 50 CFR 665.818 - Exemptions for American Samoa large vessel prohibited areas.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Exemptions for American Samoa large vessel... WESTERN PACIFIC Western Pacific Pelagic Fisheries § 665.818 Exemptions for American Samoa large vessel prohibited areas. (a) An exemption will be issued to a person who currently owns a large vessel to use...

  4. Optical emission spectroscopy at the large RF driven negative ion test facility ELISE: Instrumental setup and first results

    SciTech Connect

    Wünderlich, D.; Fantz, U.; Franzen, P.; Riedl, R.; Bonomo, F.

    2013-09-15

    One of the main topics to be investigated at the recently launched large (A{sub source}= 1.0 × 0.9 m{sup 2}) ITER relevant RF driven negative ion test facility ELISE (Extraction from a Large Ion Source Experiment) is the connection between the homogeneity of the plasma parameters close to the extraction system and the homogeneity of the extracted negative hydrogen ion beam. While several diagnostics techniques are available for measuring the beam homogeneity, the plasma parameters are determined by optical emission spectroscopy (OES) solely. First OES measurements close to the extraction system show that without magnetic filter field the vertical profile of the plasma emission is more or less symmetric, with maxima of the emission representing the projection of the plasma generation volumes, and a distinct minimum in between. The profile changes with the strength of the magnetic filter field but under all circumstances the plasma emission in ELISE is much more homogeneous compared to the smaller IPP prototype sources. Planned after this successful demonstration of the ELISE OES system is to combine OES with tomography in order to determine locally resolved values for the plasma parameters.

  5. Optical emission spectroscopy at the large RF driven negative ion test facility ELISE: Instrumental setup and first results

    NASA Astrophysics Data System (ADS)

    Wünderlich, D.; Fantz, U.; Franzen, P.; Riedl, R.; Bonomo, F.

    2013-09-01

    One of the main topics to be investigated at the recently launched large (Asource = 1.0 × 0.9 m2) ITER relevant RF driven negative ion test facility ELISE (Extraction from a Large Ion Source Experiment) is the connection between the homogeneity of the plasma parameters close to the extraction system and the homogeneity of the extracted negative hydrogen ion beam. While several diagnostics techniques are available for measuring the beam homogeneity, the plasma parameters are determined by optical emission spectroscopy (OES) solely. First OES measurements close to the extraction system show that without magnetic filter field the vertical profile of the plasma emission is more or less symmetric, with maxima of the emission representing the projection of the plasma generation volumes, and a distinct minimum in between. The profile changes with the strength of the magnetic filter field but under all circumstances the plasma emission in ELISE is much more homogeneous compared to the smaller IPP prototype sources. Planned after this successful demonstration of the ELISE OES system is to combine OES with tomography in order to determine locally resolved values for the plasma parameters.

  6. Graphene-based large area dye-sensitized solar cell modules.

    PubMed

    Casaluci, Simone; Gemmi, Mauro; Pellegrini, Vittorio; Di Carlo, Aldo; Bonaccorso, Francesco

    2016-03-01

    We demonstrate spray coating of graphene ink as a viable method for large-area fabrication of graphene-based dye-sensitized solar cell (DSSC) modules. A graphene-based ink produced by liquid phase exfoliation of graphite is spray coated onto a transparent conductive oxide substrate to realize a large area (>90 cm(2)) semi-transparent (transmittance 44%) counter-electrode (CE) replacing platinum, the standard CE material. The graphene-based CE is successfully integrated in a large-area (43.2 cm(2) active area) DSSC module achieving a power conversion efficiency of 3.5%. The approach demonstrated here paves the way to all-printed, flexible, and transparent graphene-based large-area and cost-effective photovoltaic devices on arbitrary substrates. PMID:26883743

  7. Graphene-based large area dye-sensitized solar cell modules

    NASA Astrophysics Data System (ADS)

    Casaluci, Simone; Gemmi, Mauro; Pellegrini, Vittorio; di Carlo, Aldo; Bonaccorso, Francesco

    2016-02-01

    We demonstrate spray coating of graphene ink as a viable method for large-area fabrication of graphene-based dye-sensitized solar cell (DSSC) modules. A graphene-based ink produced by liquid phase exfoliation of graphite is spray coated onto a transparent conductive oxide substrate to realize a large area (>90 cm2) semi-transparent (transmittance 44%) counter-electrode (CE) replacing platinum, the standard CE material. The graphene-based CE is successfully integrated in a large-area (43.2 cm2 active area) DSSC module achieving a power conversion efficiency of 3.5%. The approach demonstrated here paves the way to all-printed, flexible, and transparent graphene-based large-area and cost-effective photovoltaic devices on arbitrary substrates.

  8. Large area substrate for surface enhanced Raman spectroscopy (SERS) using glass-drawing technique

    DOEpatents

    Ivanov, Ilia N.; Simpson, John T.

    2012-06-26

    A method of making a large area substrate comprises drawing a plurality of tubes to form a plurality of drawn tubes, and cutting the plurality of drawn tubes into cut drawn tubes. Each cut drawn tube has a first end and a second end along the longitudinal direction of the respective cut drawn tube. The cut drawn tubes collectively have a predetermined periodicity. The method of making a large area substrate also comprises forming a metal layer on the first ends of the cut drawn tubes to provide a large area substrate.

  9. A study on large area Hamamatsu photomultipliers for Cherenkov neutrino detectors

    NASA Astrophysics Data System (ADS)

    Leonora, E.; Aiello, S.; Giordano, V.; Randazzo, N.; Lo Presti, D.; Bonanno, D.; Longhitano, F.; Sipala, V.

    2015-11-01

    Many of the existing neutrino telescopes use large area photomultipliers integrated into transparent glass vessels to make the detection element called ``optical module''. The characteristics of the photomultipliers have a severe impact on the performance of the whole detectors. This paper describes a large work of characterization of large area photomultipliers performed in the frame of R&D activities of large volume underwater neutrino detectors. Dedicated studies are also reported about noise pulses, super bialkali photocathode photomultipliers, ageing effects, influences of the Earth's magnetic field and on the effects of the external glass vessels on the optical module's noise pulses.

  10. The mechanism of the area negative thermal expansion in KBe2BO3F2 family crystals: A first-principles study

    NASA Astrophysics Data System (ADS)

    Jiang, Xingxing; Molokeev, Maxim S.; Li, Wei; Wu, Shaofan; Lin, Zheshuai; Wu, Yicheng; Chen, Chuangtian

    2016-02-01

    A very recent study demonstrated that the KBe2BO3F2 (KBBF) family of crystals, including KBBF, RbBe2BO3F2, and CsBe2BO3F2, are the only known borates exhibiting a rarely occurring isotropic area negative thermal expansion (NTE) behavior, over a very large temperature range. In the present work, the NTE mechanism in these crystals is comprehensively investigated using the first-principles calculations. It is revealed that the area NTE behavior mainly originates from the concerted distortion of [BeO3F] tetrahedra in the two-dimensional [Be2BO3F2]∞ framework with respect to temperature, while the [BO3] triangles remain almost rigid. Moreover, the different magnitude of NTE effect in the three crystals is attributed to the interaction difference between the alkali metal atoms (K, Rb, or Cs) and the [Be2BO3F2]∞ layer.

  11. Comparison of Optical Emission Spectroscopy and Cavity Ring-Down Spectroscopy in Large-Scaled Negative-Ion Source

    SciTech Connect

    Ikeda, K.; Nakano, H.; Tsumori, K.; Kaneko, O.; Kisaki, M.; Nagaoka, K.; Osakabe, M.; Takeiri, Y.; Fantz, U.

    2011-09-26

    Optical emission spectroscopy (OES) and cavity ring-down spectroscopy (CRDS) systems are installed in a 1/3-scaled negative hydrogen-ion source at the National Institute for Fusion Science testbed to investigate the dynamics of H{sup -} ions in the extraction region near the plasma grid. The signal form of the H{sup -} ion density rapidly drops after beam extraction on applying a low-bias voltage. A similar signal drop appears in the intensity of the hydrogen Balmer-line emission measured by OES and is caused by decreasing atomic hydrogen produced by mutual neutralization effects between H{sup -} and H{sup +}. Shot trend of the beam currents are similar to the H{sup -} density and H{sub {alpha}}/H{sub {beta}} in the extraction region, which increases twice as large immediately after Cs seeding. We observe a linear correlation between the H{sup -} density and the inclination of H{sub {alpha}}/H{sub {beta}} which allows for experimentally benchmarking the OES measurement with that of CRDS. Thus, this approach is used for estimating the H{sup -} density by OES in negative-ion sources for high-energy neutral beam injector.

  12. Dominant-Negative Myosin Va Impairs Retrograde but Not Anterograde Axonal Transport of Large Dense Core Vesicles

    PubMed Central

    Bittins, Claudia Margarethe; Eichler, Tilo Wolf; Hammer, John A.; Gerdes, Hans-Hermann

    2013-01-01

    Axonal transport of peptide and hormone-containing large dense core vesicles (LDCVs) is known to be a microtubule-dependent process. Here, we suggest a role for the actin-based motor protein myosin Va specifically in retrograde axonal transport of LDCVs. Using live-cell imaging of transfected hippocampal neurons grown in culture, we measured the speed, transport direction, and the number of LDCVs that were labeled with ectopically expressed neuropeptide Y fused to EGFP. Upon expression of a dominant-negative tail construct of myosin Va, a general reduction of movement in both dendrites and axons was observed. In axons, it was particularly interesting that the retrograde speed of LDCVs was significantly impaired, although anterograde transport remained unchanged. Moreover, particles labeled with the dominant-negative construct often moved in the retrograde direction but rarely in the anterograde direction. We suggest a model where myosin Va acts as an actin-dependent vesicle motor that facilitates retrograde axonal transport. PMID:19787448

  13. 14. BUILDING 312, INTERIOR, SIXTH FLOOR, LARGE OFFICE/STOREROOM AREA, FROM ...

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

    14. BUILDING 312, INTERIOR, SIXTH FLOOR, LARGE OFFICE/STOREROOM AREA, FROM SOUTHEASTERN CORNER OF BUILDING, LOOKING WEST. - Oakland Naval Supply Center, General Storehouses, Between Third & Fourth Streets, North of A Street, Oakland, Alameda County, CA

  14. Global Distributions of Large Exposed Areas of Lunar Major Minerals and Its Implications

    NASA Astrophysics Data System (ADS)

    Yamamoto, S.; Nakamura, R.; Matsunaga, T.; Ishihara, Y.; Ohtake, M.; Haruyama, J.

    2016-05-01

    We review the global distributions of large exposure areas of the various lunar major minerals revealed by the recent remote-sensing hyperspectral observations, and discuss possible implications for lunar crust and mantle.

  15. Large area crop inventory experiment crop assessment subsystem software requirements document

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The functional data processing requirements are described for the Crop Assessment Subsystem of the Large Area Crop Inventory Experiment. These requirements are used as a guide for software development and implementation.

  16. MUTAGENIC CHARACTERISTICS OF RIVER WATERS FLOWING THROUGH LARGE METROPOLITAN AREAS IN NORTH AMERICA

    EPA Science Inventory

    Mutagenic characteristics of river waters flowing through large metropolitan areas in North America

    The hanging technique using blue rayon, which specifically adsorbs mutagens with multicyclic planar structures, has the advantages over most conventional methods of not havi...

  17. Sleep deprivation causes memory deficits by negatively impacting neuronal connectivity in hippocampal area CA1.

    PubMed

    Havekes, Robbert; Park, Alan J; Tudor, Jennifer C; Luczak, Vincent G; Hansen, Rolf T; Ferri, Sarah L; Bruinenberg, Vibeke M; Poplawski, Shane G; Day, Jonathan P; Aton, Sara J; Radwańska, Kasia; Meerlo, Peter; Houslay, Miles D; Baillie, George S; Abel, Ted

    2016-01-01

    Brief periods of sleep loss have long-lasting consequences such as impaired memory consolidation. Structural changes in synaptic connectivity have been proposed as a substrate of memory storage. Here, we examine the impact of brief periods of sleep deprivation on dendritic structure. In mice, we find that five hours of sleep deprivation decreases dendritic spine numbers selectively in hippocampal area CA1 and increased activity of the filamentous actin severing protein cofilin. Recovery sleep normalizes these structural alterations. Suppression of cofilin function prevents spine loss, deficits in hippocampal synaptic plasticity, and impairments in long-term memory caused by sleep deprivation. The elevated cofilin activity is caused by cAMP-degrading phosphodiesterase-4A5 (PDE4A5), which hampers cAMP-PKA-LIMK signaling. Attenuating PDE4A5 function prevents changes in cAMP-PKA-LIMK-cofilin signaling and cognitive deficits associated with sleep deprivation. Our work demonstrates the necessity of an intact cAMP-PDE4-PKA-LIMK-cofilin activation-signaling pathway for sleep deprivation-induced memory disruption and reduction in hippocampal spine density. PMID:27549340

  18. Sleep deprivation causes memory deficits by negatively impacting neuronal connectivity in hippocampal area CA1

    PubMed Central

    Havekes, Robbert; Park, Alan J; Tudor, Jennifer C; Luczak, Vincent G; Hansen, Rolf T; Ferri, Sarah L; Bruinenberg, Vibeke M; Poplawski, Shane G; Day, Jonathan P; Aton, Sara J; Radwańska, Kasia; Meerlo, Peter; Houslay, Miles D; Baillie, George S; Abel, Ted

    2016-01-01

    Brief periods of sleep loss have long-lasting consequences such as impaired memory consolidation. Structural changes in synaptic connectivity have been proposed as a substrate of memory storage. Here, we examine the impact of brief periods of sleep deprivation on dendritic structure. In mice, we find that five hours of sleep deprivation decreases dendritic spine numbers selectively in hippocampal area CA1 and increased activity of the filamentous actin severing protein cofilin. Recovery sleep normalizes these structural alterations. Suppression of cofilin function prevents spine loss, deficits in hippocampal synaptic plasticity, and impairments in long-term memory caused by sleep deprivation. The elevated cofilin activity is caused by cAMP-degrading phosphodiesterase-4A5 (PDE4A5), which hampers cAMP-PKA-LIMK signaling. Attenuating PDE4A5 function prevents changes in cAMP-PKA-LIMK-cofilin signaling and cognitive deficits associated with sleep deprivation. Our work demonstrates the necessity of an intact cAMP-PDE4-PKA-LIMK-cofilin activation-signaling pathway for sleep deprivation-induced memory disruption and reduction in hippocampal spine density. DOI: http://dx.doi.org/10.7554/eLife.13424.001 PMID:27549340

  19. Polycrystalline CVD diamond detector: Fast response and high sensitivity with large area

    SciTech Connect

    Liu, Linyue Zhang, Xianpeng; Zhong, Yunhong; Ouyang, Xiaoping Zhang, Jianfu

    2014-01-15

    Polycrystalline diamond was successfully used to fabricate a large area (diameter up to 46 mm) radiation detector. It was proven that the developed detector shows a fast pulsed response time and a high sensitivity, therefore its rise time is lower than 5 ns, which is two times faster than that of a Si-PIN detector of the same size. And because of the large sensitive area, this detector shows good dominance in fast pulsed and low density radiation detection.

  20. Combining large area fluorescence with multiphoton microscopy for improved detection of oral epithelial neoplasia (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Pal, Rahul; Yang, Jinping; Qiu, Suimin; McCammon, Susan; Resto, Vicente; Vargas, Gracie

    2016-03-01

    Volumetric Multiphoton Autofluorescence Microscopy (MPAM) and Second Harmonic Generation Microscopy (SHGM) show promise for revealing indicators of neoplasia representing the complex microstructural organization of mucosa, potentially providing high specificity for detection of neoplasia, but is limited by small imaging area. Large area fluorescence methods on the other hand show high sensitivity appropriate for screening but are hampered by low specificity. In this study, we apply MPAM-SHGM following guidance from large area fluorescence, by either autofluorescence or a targeted metabolic fluorophore, as a potentially clinically viable approach for detection of oral neoplasia. Sites of high neoplastic potentially were identified by large area red/green autofluorescence or by a fluorescently labelled deoxy-glucose analog, 2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-D-glucose (2-NBDG) to highlight areas of high glucose uptake across the buccal pouch of a hamster model for OSCC. Follow-up MPAM-SHGM was conducted on regions of interests (ROIs) to assess whether microscopy would reveal microscopic features associated with neoplasia to confirm or exclude large area fluorescence findings. Parameters for analysis included cytologic metrics, 3D epithelial connective tissue interface metrics (MPAM-SHGM) and intensity of fluorescence (widefield). Imaged sites were biopsied and processed for histology and graded by a pathologist. A small sample of human ex vivo tissues were also imaged. A generalized linear model combining image metrics from large area fluorescence and volumetric MPAM-SHGM indicated the ability to delineate normal and inflammation from neoplasia.

  1. Results of testing the energy dispersive Si detector with large working area

    NASA Astrophysics Data System (ADS)

    Gogolev, A. S.; Hampai, D.; Khusainov, A. Kh.; Zhukov, M. P.; Dabagov, S. B.; Potylitsyn, A. P.; Liedl, A.; Polese, C.

    2015-07-01

    In this work the testing results for the spectrometer with a large sensitive area developed for the crystal monitoring station of modern hadron accelerator control systems used for the beam collimation are presented. The investigations were carried out at the XLab Frascati LNF laboratory aiming mostly in studying the detector sensitivity uniformity throughout the sensor area.

  2. Detecting Change in Landscape Greenness over Large Areas: An Example for New Mexico, USA

    EPA Science Inventory

    Monitoring and quantifying changes in vegetation cover over large areas using remote sensing can potentially detect large-scale, slow changes (e.g., climate change), as well as more local and rapid changes (e.g., fire, land development). A useful indicator for detecting change i...

  3. Large-scale synthesis of high-quality hexagonal boron nitride nanosheets for large-area graphene electronics.

    PubMed

    Lee, Kang Hyuck; Shin, Hyeon-Jin; Lee, Jinyeong; Lee, In-yeal; Kim, Gil-Ho; Choi, Jae-Young; Kim, Sang-Woo

    2012-02-01

    Hexagonal boron nitride (h-BN) has received a great deal of attention as a substrate material for high-performance graphene electronics because it has an atomically smooth surface, lattice constant similar to that of graphene, large optical phonon modes, and a large electrical band gap. Herein, we report the large-scale synthesis of high-quality h-BN nanosheets in a chemical vapor deposition (CVD) process by controlling the surface morphologies of the copper (Cu) catalysts. It was found that morphology control of the Cu foil is much critical for the formation of the pure h-BN nanosheets as well as the improvement of their crystallinity. For the first time, we demonstrate the performance enhancement of CVD-based graphene devices with large-scale h-BN nanosheets. The mobility of the graphene device on the h-BN nanosheets was increased 3 times compared to that without the h-BN nanosheets. The on-off ratio of the drain current is 2 times higher than that of the graphene device without h-BN. This work suggests that high-quality h-BN nanosheets based on CVD are very promising for high-performance large-area graphene electronics. PMID:22220633

  4. CVD diamond wafers as large-area thermoluminescence detectors for measuring the spatial distribution of dose

    NASA Astrophysics Data System (ADS)

    Marczewska, B.; Bilski, P.; Olko, P.; Olko, P.; Nesládek, M.; Bergonzo, P.; Rbisz, M.; Waligórski, M. P. R.

    2003-09-01

    The applicability of large-area CVD diamond wafers (diameter about 5 cm, thickness about 0.1 mm), read out as thermoluminescence (TL) detectors, for assessing two-dimensional (2-D) dose distribution over their area, was investigated. To obtain 2-D TL images, a special TL reader equipped with large-area planchet and a CCD camera instead of the usual PM tube was developed. Several 2-D TL images: of an alpha source (Am-241), a Ra-226 needle source and a Ru-106 ophthalmic applicator, were measured and high-resolution digital images obtained. Our preliminary results demonstrate the potential capability of large-area CVD diamond wafers, read out as TL detectors, in 2-D dosimetry for medical applications. (

  5. Rapid confocal imaging of large areas of excised tissue with strip mosaicing

    PubMed Central

    Abeytunge, Sanjee; Li, Yongbiao; Larson, Bjorg; Toledo-Crow, Ricardo; Rajadhyaksha, Milind

    2011-01-01

    Imaging large areas of tissue rapidly and with high resolution may enable rapid pathology at the bedside. The limited field of view of high-resolution microscopes requires the merging of multiple images that are taken sequentially to cover a large area. This merging or mosaicing of images requires long acquisition and processing times, and produces artifacts. To reduce both time and artifacts, we developed a mosaicing method on a confocal microscope that images morphology in large areas of excised tissue with sub-cellular detail. By acquiring image strips with aspect ratios of 10:1 and higher (instead of the standard ∼1:1) and “stitching” them in software, our method images 10×10 mm2 area of tissue in about 3 min. This method, which we call “strip mosaicing,” is currently three times as fast as our previous method. PMID:21639560

  6. The effect of gettering on areal inhomogeneities in large-area multicrystalline-silicon solar cells

    SciTech Connect

    Gee, J.M.; Sopori, B.L.

    1997-10-01

    Multicrystalline-silicon (mc-Si) materials and cells feature large areal variations in material and junction quality. The regions with poor device quality have been predicted to have more recombination current at forward bias than a simple area-weighted average due to the parallel interconnection of the good and bad regions by the front junction. The authors have examined the effect of gettering on areal inhomogeneities in large-area mc-Si cells. Cells with large areal inhomogeneities were found to have increased non-ideal recombination current, which is in line with theoretical predictions. Phosphorus-diffusion and aluminum-alloy gettering of mc-Si was found to reduce the areal inhomogeneities and improve large-area mc-Si device performance.

  7. Steady-state operation of a large-area high-power RF ion source for the neutral beam injector

    NASA Astrophysics Data System (ADS)

    Chang, Doo-Hee; Park, Min; Jeong, Seung Ho; Kim, Tae-Seong; Lee, Kwang Won; In, Sang Ryul

    2014-10-01

    A large-area high-power RF-driven ion source is being developed in Germany for the heating and current drive (H&CD) of an ITER device. Negative hydrogen ion sources are the major components of neutral beam injection systems in future large-scale fusion devices such as an the ITER and the DEMO. The first and the second long-pulse ion sources (LPIS-1 and LPIS-2) have been successfully developed with a magnetic-bucket plasma generator, including a filament heating structure for the first NBI (NBI-1) system of the KSTAR tokamak. A development plan exists for a large-area high-power RF ion source for steady-state operation (more than 300 seconds) at the Korea Atomic Energy Research Institute (KAERI) to extract positive ions, which can be used for the NBI heating and current drive systems, and to extract negative ions for future fusion devices such as a Fusion Neutron Source and Korea — DEMO. The RF ion source consists of a driver region, including a helical antenna and a discharge chamber, and an expansion region (magnetic bucket of the prototype LPIS-1). RF power can be transferred at up to 10 kW with a fixed frequency of 2 MHz through an optimized RF matching system. An actively water-cooled Faraday shield is located inside the driver region of the ion source for stable and steady-state operation of the RF discharge. The uniformities of the plasma parameters are measured at the lowest area of the expansion bucket by using two RF-compensated electrostatic probes along the directions of the short and the long dimensions of the expansion region.

  8. Development of broadband X-ray interference lithography large area exposure system

    NASA Astrophysics Data System (ADS)

    Xue, Chaofan; Wu, Yanqing; Zhu, Fangyuan; Yang, Shumin; Liu, Haigang; Zhao, Jun; Wang, Liansheng; Tai, Renzhong

    2016-04-01

    The single-exposure patterned area is about several 102 × 102 μm2 which is mainly decided by the mask area in multi-beam X-ray interference lithography (XIL). The exposure area is difficult to stitch to a larger one because the patterned area is surrounded by 0th diffraction exposure areas. To block the 0th diffraction beams precisely and effectively, a new large area exposure technology is developed in the Shanghai Synchrotron Radiation Facility by applying an order-sorting aperture with a new in situ monitoring scheme in the XIL system. The patterned area could be stitched readily up to several square centimeters and even bigger by this technology.

  9. Comparison of Multi-Scale Digital Elevation Models for Defining Waterways and Catchments Over Large Areas

    NASA Astrophysics Data System (ADS)

    Harris, B.; McDougall, K.; Barry, M.

    2012-07-01

    Digital Elevation Models (DEMs) allow for the efficient and consistent creation of waterways and catchment boundaries over large areas. Studies of waterway delineation from DEMs are usually undertaken over small or single catchment areas due to the nature of the problems being investigated. Improvements in Geographic Information Systems (GIS) techniques, software, hardware and data allow for analysis of larger data sets and also facilitate a consistent tool for the creation and analysis of waterways over extensive areas. However, rarely are they developed over large regional areas because of the lack of available raw data sets and the amount of work required to create the underlying DEMs. This paper examines definition of waterways and catchments over an area of approximately 25,000 km2 to establish the optimal DEM scale required for waterway delineation over large regional projects. The comparative study analysed multi-scale DEMs over two test areas (Wivenhoe catchment, 543 km2 and a detailed 13 km2 within the Wivenhoe catchment) including various data types, scales, quality, and variable catchment input parameters. Historic and available DEM data was compared to high resolution Lidar based DEMs to assess variations in the formation of stream networks. The results identified that, particularly in areas of high elevation change, DEMs at 20 m cell size created from broad scale 1:25,000 data (combined with more detailed data or manual delineation in flat areas) are adequate for the creation of waterways and catchments at a regional scale.

  10. Large area projection liquid-crystal video display system with inherent grid pattern optically removed

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang (Inventor)

    1992-01-01

    A relatively small and low-cost system is provided for projecting a large and bright television image onto a screen. A miniature liquid crystal array is driven by video circuitry to produce a pattern of transparencies in the array corresponding to a television image. Light is directed against the rear surface of the array to illuminate it, while a projection lens lies in front of the array to project the image of the array onto a large screen. Grid lines in the liquid crystal array are eliminated by a spacial filter which comprises a negative of the Fourier transform of the grid.

  11. Coatings for large-area low-cost solar concentrators and reflectors

    SciTech Connect

    Martin, P.M.; Affinito, J.D.; Gross, M.E.; Bennett, W.D.

    1994-07-01

    Seven years ago, Pacific Northwest Laboratory constructed a large-optics coating facility to develop and fabricate high-performance multilayer laser-mirror coatings on large substrates. With the reduction of DoD funding for the development of optical coatings for large optics, new applications for this chamber were sought. In addition to new DoD applications, the facility is now being used to fabricate multilayer enhanced-metal reflectors for low-cost large-area solar concentrators using both magnetron-sputtered metal and dielectric coatings, with future extension to vacuum-evaporated polymer coatings. Other new applications include: Ti/Ti:Al lamellar composites on flexible webs; EMI cladding for heater wire; EMI-shielding coatings on flexible webs; microwave-absorbing coatings on flexible webs; heat mirrors; bulk micromachining; and protective coatings on cylindrical substrates and webs. The facility has also been established as a DoD user facility for development and experimentation in large-area optical coatings. This paper describes important changes in the large-optics coating chamber and additional deposition equipment that has been added to pursue these new non-DoD technological areas. Solar reflectors and the resulting new coatings will be described. Future work and new technological areas being pursued will also be discussed.

  12. Simple room-temperature preparation of high-yield large-area graphene oxide.

    PubMed

    Huang, N M; Lim, H N; Chia, C H; Yarmo, M A; Muhamad, M R

    2011-01-01

    Graphene has attracted much attention from researchers due to its interesting mechanical, electrochemical, and electronic properties. It has many potential applications such as polymer filler, sensor, energy conversion, and energy storage devices. Graphene-based nanocomposites are under an intense spotlight amongst researchers. A large amount of graphene is required for preparation of such samples. Lately, graphene-based materials have been the target for fundamental life science investigations. Despite graphene being a much sought-after raw material, the drawbacks in the preparation of graphene are that it is a challenge amongst researchers to produce this material in a scalable quantity and that there is a concern about its safety. Thus, a simple and efficient method for the preparation of graphene oxide (GO) is greatly desired to address these problems. In this work, one-pot chemical oxidation of graphite was carried out at room temperature for the preparation of large-area GO with ~100% conversion. This high-conversion preparation of large-area GO was achieved using a simplified Hummer's method from large graphite flakes (an average flake size of 500 μm). It was found that a high degree of oxidation of graphite could be realized by stirring graphite in a mixture of acids and potassium permanganate, resulting in GO with large lateral dimension and area, which could reach up to 120 μm and ~8000 μm(2), respectively. The simplified Hummer's method provides a facile approach for the preparation of large-area GO. PMID:22267928

  13. Fast and large-area growth of uniform MoS2 monolayers on molybdenum foils

    NASA Astrophysics Data System (ADS)

    Tai, Guoan; Zeng, Tian; Yu, Jin; Zhou, Jianxin; You, Yuncheng; Wang, Xufeng; Wu, Hongrong; Sun, Xu; Hu, Tingsong; Guo, Wanlin

    2016-01-01

    A controllable synthesis of two-dimensional crystal monolayers in a large area is a prerequisite for potential applications, but the growth of transition metal dichalcogenide monolayers in a large area with spatial homogeneity remains a great challenge. Here we report a novel and efficient method to fabricate large-scale MoS2 monolayers by direct sulfurization of pre-annealed molybdenum foil surfaces with large grain boundaries of more than 50 μm in size at elevated temperatures. Continuous MoS2 monolayers can be formed uniformly by sulfurizing the Mo foils in sulfur vapor at 600 °C within 1 min. At a lower temperature even down to 500 °C, uniform MoS2 monolayers can still be obtained but in a much longer sulfurizing duration. It is demonstrated that the formed monolayers can be nondestructively transferred onto arbitrary substrates by removing the Mo foil using diluted ferric chloride solution and can be successfully fabricated into photodetectors. The results show a novel avenue to efficiently fabricate two-dimensional crystals in a large area in a highly controllable way and should have great potential for the development of large-scale applications of two-dimensional crystals in electrophotonic systems.A controllable synthesis of two-dimensional crystal monolayers in a large area is a prerequisite for potential applications, but the growth of transition metal dichalcogenide monolayers in a large area with spatial homogeneity remains a great challenge. Here we report a novel and efficient method to fabricate large-scale MoS2 monolayers by direct sulfurization of pre-annealed molybdenum foil surfaces with large grain boundaries of more than 50 μm in size at elevated temperatures. Continuous MoS2 monolayers can be formed uniformly by sulfurizing the Mo foils in sulfur vapor at 600 °C within 1 min. At a lower temperature even down to 500 °C, uniform MoS2 monolayers can still be obtained but in a much longer sulfurizing duration. It is demonstrated that the

  14. Large negative magnetoresistance induced by interplay between smooth disorder and antidots in AlGaN/GaN HEMT structures

    NASA Astrophysics Data System (ADS)

    Mishra, M. K.; Sharma, R. K.; Tyagi, R.; Manchanda, R.; Pandey, A. K.; Thakur, O. P.; Muralidharan, R.

    2016-04-01

    Large low temperature negative magnetoresistance (NMR) experimentally observed in AlGaN/GaN high electron mobility transistors (HEMT) structures grown by metalorganic chemical vapour deposition on sapphire substrate has been reported. A linear B ‑1 ln B dependence of magnetoresistance observed in our samples indicates the presence of random antidot array together with smooth disorder. It is proposed that the antidots are linked with high bandgap AlN rich regions formed due to possible Al–Ga segregation at the interface during growth and the smooth random disorder is due to interface roughness. The antidot density is estimated to be of ∼7 to 8 × 1010 cm‑2 in our samples. The magnitude of NMR is also correlated with the extent of interface roughness indicated by x-ray reflectivity. It is also proposed that the formation of antidots is related with the lattice mismatch between substrate and epitaxial heterostructures. The NMR in AlGaN/GaN HEMT structures grown on SiC substrates having relatively lower lattice mismatch has been shown to have a usual B 2 and ln T dependences indicating only electron–electron interaction and absence of antidot-like scatterers.

  15. Alterations in the thymocyte phenotype of EphB-deficient mice largely affect the double negative cell compartment

    PubMed Central

    Alfaro, David; Muñoz, Juan José; García-Ceca, Javier; Cejalvo, Teresa; Jiménez, Eva; Zapata, Agustín

    2008-01-01

    In the present study, we have analysed the phenotype of EphB2 and/or EphB3 deficient thymocytes confirming and extending previous studies on the role of this family of molecules in T-cell differentiation. In all mutant thymuses statistically significant reduced cell contents were observed. This reduction of thymic cellularity correlated with increased proportions of apoptotic cells, largely both double negative (DN; CD4− CD8−) and double positive (CD4+ CD8+) cells, and decreased proportions of DN cycling cells. Adult deficient thymuses also showed increased proportions of DN cells but not significant variations in the percentages of other thymocyte subsets. In absolute terms, the thymocyte number decreased significantly in all thymocyte compartments from the DN3 (CD44− CD25+) cell stage onward, without variations in the numbers of both DN1 (CD44+ CD25−) and DN2 (CD44+ CD25+) cells. Remarkably, all these changes also occurred from the 15-day fetal EphB2 and/or EphB3 deficient mice, suggesting that adult phenotype results from the gradual accumulations of defects appearing early in the thymus ontogeny. As a reflection of thymus condition, a reduction in the number of T lymphocytes occurred in the peripheral blood and mesenteric lymph nodes, but not in spleen, maintaining the proportions of T-cell subsets defined by CD4/CD8 marker expression, in all cases. PMID:18397270

  16. High-ion temperature experiments with negative-ion-based neutral beam injection heating in Large Helical Device

    NASA Astrophysics Data System (ADS)

    Takeiri, Y.; Morita, S.; Tsumori, K.; Ikeda, K.; Oka, Y.; Osakabe, M.; Nagaoka, K.; Goto, M.; Miyazawa, J.; Masuzaki, S.; Ashikawa, N.; Yokoyama, M.; Murakami, S.; Narihara, K.; Yamada, I.; Kubo, S.; Shimozuma, T.; Inagaki, S.; Tanaka, K.; Peterson, B. J.; Ida, K.; Kaneko, O.; Komori, A.; LHD Experimental Group

    2005-07-01

    High-Z plasmas have been produced with Ar and/or Ne gas fuelling to increase the ion temperature in Large Helical Device (LHD) plasmas heated with high-energy negative-ion-based neutral beam injection (NBI). Although the electron heating is dominant in the high-energy NBI heating, the direct ion heating power is significantly enhanced in low-density plasmas due to both an increase in the beam absorption (ionization) power and a reduction of the ion density in the high-Z plasmas. Intensive neon- and/or argon-glow discharge cleaning works well to suppress dilution of the high-Z plasmas with wall-absorbed hydrogen. As a result, the ion temperature increases with an increase in the ion heating power normalized by the ion density and reaches 10 keV. An increase in the ion temperature is also observed with the addition of centrally focused electron cyclotron resonance heating to a low-density and high-Z NBI plasma, suggesting improvement of the ion transport. The results obtained in the high-Z plasma experiments with high-energy NBI heating suggest that an increase in the direct ion heating power and improvement of the ion transport are essential to ion temperature rise, and that a high-ion temperature could be obtained as well in hydrogen plasmas with low-energy positive-NBI heating which is planned in the near future in the LHD.

  17. Vanadium Dioxide as a Natural Disordered Metamaterial: Perfect Thermal Emission and Large Broadband Negative Differential Thermal Emittance

    NASA Astrophysics Data System (ADS)

    Kats, Mikhail A.; Blanchard, Romain; Zhang, Shuyan; Genevet, Patrice; Ko, Changhyun; Ramanathan, Shriram; Capasso, Federico

    2013-10-01

    We experimentally demonstrate that a thin (approximately 150-nm) film of vanadium dioxide (VO2) deposited on sapphire has an anomalous thermal emittance profile when heated, which arises because of the optical interaction between the film and the substrate when the VO2 is at an intermediate state of its insulator-metal transition (IMT). Within the IMT region, the VO2 film comprises nanoscale islands of the metal and dielectric phases and can thus be viewed as a natural, disordered metamaterial. This structure displays “perfect” blackbodylike thermal emissivity over a narrow wavelength range (approximately 40cm-1), surpassing the emissivity of our black-soot reference. We observe large broadband negative differential thermal emittance over a >10°C range: Upon heating, the VO2-sapphire structure emits less thermal radiation and appears colder on an infrared camera. Our experimental approach allows for a direct measurement and extraction of wavelength- and temperature-dependent thermal emittance. We anticipate that emissivity engineering with thin-film geometries comprising VO2 and other thermochromic materials will find applications in infrared camouflage, thermal regulation, and infrared tagging and labeling.

  18. Uniformity of large-area bilayer graphene grown by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Sheng, Yuewen; Rong, Youmin; He, Zhengyu; Fan, Ye; Warner, Jamie H.

    2015-10-01

    Graphene grown by chemical vapor deposition (CVD) on copper foils is a viable method for large area films for transparent conducting electrode (TCE) applications. We examine the spatial uniformity of large area films on the centimeter scale when transferred onto both Si substrates with 300 nm oxide and flexible transparent polyethylene terephthalate substrates. A difference in the quality of graphene, as measured by the sheet resistance and transparency, is found for the areas at the edges of large sheets that depends on the supporting boat used for the CVD growth. Bilayer graphene is grown with uniform properties on the centimeter scale when a flat support is used for CVD growth. The flat support provides consistent delivery of precursor to the copper catalyst for graphene growth. These results provide important insights into the upscaling of CVD methods for growing high quality graphene and its transfer onto flexible substrates for potential applications as a TCE.

  19. Design of a broadband ultra-large area acoustic cloak based on a fluid medium

    NASA Astrophysics Data System (ADS)

    Zhu, Jian; Chen, Tianning; Liang, Qingxuan; Wang, Xiaopeng; Jiang, Ping

    2014-10-01

    A broadband ultra-large area acoustic cloak based on fluid medium was designed and numerically implemented with homogeneous metamaterials according to the transformation acoustics. In the present work, fluid medium as the body of the inclusion could be tuned by changing the fluid to satisfy the variant acoustic parameters instead of redesign the whole cloak. The effective density and bulk modulus of the composite materials were designed to agree with the parameters calculated from the coordinate transformation methodology by using the effective medium theory. Numerical simulation results showed that the sound propagation and scattering signature could be controlled in the broadband ultra-large area acoustic invisibility cloak, and good cloaking performance has been achieved and physically realized with homogeneous materials. The broadband ultra-large area acoustic cloaking properties have demonstrated great potentials in the promotion of the practical applications of acoustic cloak.

  20. Large-Area Chemical and Biological Decontamination Using a High Energy Arc Lamp (HEAL) System.

    SciTech Connect

    Duty, Chad E; Smith, Rob R; Vass, Arpad Alexander; Ilgner, Ralph H; Brown, Gilbert M

    2008-01-01

    Methods for quickly decontaminating large areas exposed to chemical and biological (CB) warfare agents can present significant logistical, manpower, and waste management challenges. Oak Ridge National Laboratory (ORNL) is pursuing an alternate method to decompose CB agents without the use of toxic chemicals or other potentially harmful substances. This process uses a high energy arc lamp (HEAL) system to photochemically decompose CB agents over large areas (12 m2). Preliminary tests indicate that more than 5 decades (99.999%) of an Anthrax spore simulant (Bacillus globigii) were killed in less than 7 seconds of exposure to the HEAL system. When combined with a catalyst material (TiO2) the HEAL system was also effective against a chemical agent simulant, diisopropyl methyl phosphonate (DIMP). These results demonstrate the feasibility of a rapid, large-area chemical and biological decontamination method that does not require toxic or corrosive reagents or generate hazardous wastes.

  1. Soil Property Mapping Over Large Areas Using Sparse Ad-hoc Samples

    NASA Astrophysics Data System (ADS)

    Zhu, A.; Liu, J.

    2011-12-01

    Information on spatial variation of soil properties over large areas is a critical input for environmental modeling at large scales. Yet, quality information on soil spatial variation over large areas is difficult to obtain due to the large number of field samples required. Existing samples are often sparse and ad-hoc. The soil property maps created from these samples using existing techniques are not only at low quality but also lack the uncertainty information. This paper presents a new approach to map soil properties and quantify uncertainty in the derived soil property maps over large areas using sparse and ad-hoc samples. The underlying assumption of this new approach is the soil-landscape concept which stipulates that the more similar the environment conditions between two locations the more similar the soil property values are between the two sites. Under this assumption each sample can be considered as a representative over areas of similar environmental conditions. The level of representation of an individual sample for an unsampled location can be approximated by the similarity between their respective environment conditions. Based on this "individual representation" concept and with a Case-based Reasoning (CBR) approach soil property values at unsampled locations can be predicted and the uncertainty associated with each prediction can also be quantified based on their environmental similarity to individual samples. A case study over the Illy Region, a 50,000 km2 area in Xinjiang, Northwest China, has demonstrated that the approach can be an effective alternative for mapping soil property and quantifying uncertainty over large areas with sparse and ad-hoc samples.

  2. Synthesis and characterization of large specific surface area nanostructured amorphous silica materials.

    PubMed

    Marquez-Linares, Francisco; Roque-Malherbe, Rolando M A

    2006-04-01

    Large specific surface area materials attract wide attention because of their applications in adsorption, catalysis, and nanotechnology. In the present study, we describe the synthesis and characterization of nanostructured amorphous silica materials. These materials were obtained by means of a modification of the Stobe-Fink-Bohn (SFB) method. The morphology and essential features of the synthesized materials have been studied using an automated surface area and pore size analyzer and scanning electron microscopy. The existence of a micro/mesoporous structure in the obtained materials has been established. It was also found that the obtained particle packing materials show large specific surface area up to 1,600 m2/g. (To our best knowledge, there is no any reported amorphous silica material with such a higher specific surface area.) The obtained materials could be useful in the manufacture of adsorbents, catalyst supports, and other nanotechnological applications. PMID:16736774

  3. Synthesis of self-assembled large area films of complex hierarchical PZT clusters

    NASA Astrophysics Data System (ADS)

    Pratap Chaudhary, Raghvendra; Saxena, Sumit; Kmar, Amit; Bharadwaj, Rajesh; Shukla, Shobha

    2016-02-01

    The ability to bridge nano-micro interface for applications in functional miniaturized devices is of fundamental interest. We have synthesized novel large area films of complex hierarchical micro-flower morphologies of piezo-ceramics using hydrothermal reactions. The overall size of the samples produced is ∼cm2. The growth morphologies are found to be dependent on concentration and pressure inside the reaction chamber. This can be used to deterministically grow these complex multi-scaled microstructures over a large area. These results outline a strategy for growth of omni-directional microstructures by utilizing self assembly processes.

  4. An Analysis Methodology for the Gamma-ray Large Area Space Telescope

    NASA Technical Reports Server (NTRS)

    Morris, Robin D.; Cohen-Tanugi, Johann

    2004-01-01

    The Large Area Telescope (LAT) instrument on the Gamma Ray Large Area Space Telescope (GLAST) has been designed to detect high-energy gamma rays and determine their direction of incidence and energy. We propose a reconstruction algorithm based on recent advances in statistical methodology. This method, alternative to the standard event analysis inherited from high energy collider physics experiments, incorporates more accurately the physical processes occurring in the detector, and makes full use of the statistical information available. It could thus provide a better estimate of the direction and energy of the primary photon.

  5. Data acquisition and control system for high-performance large-area CCD systems

    NASA Astrophysics Data System (ADS)

    Afanasieva, I. V.

    2015-04-01

    Astronomical CCD systems based on second-generation DINACON controllers were developed at the SAO RAS Advanced Design Laboratory more than seven years ago and since then have been in constant operation at the 6-meter and Zeiss-1000 telescopes. Such systems use monolithic large-area CCDs. We describe the software developed for the control of a family of large-area CCD systems equipped with a DINACON-II controller. The software suite serves for acquisition, primary reduction, visualization, and storage of video data, and also for the control, setup, and diagnostics of the CCD system.

  6. A novel method for the activity measurement of large-area beta reference sources.

    PubMed

    Stanga, D; De Felice, P; Keightley, J; Capogni, M; Ioan, M R

    2016-03-01

    A novel method has been developed for the activity measurement of large-area beta reference sources. It makes use of two emission rate measurements and is based on the weak dependence between the source activity and the activity distribution for a given value of transmission coefficient. The method was checked experimentally by measuring the activity of two ((60)Co and (137)Cs) large-area reference sources constructed from anodized aluminum foils. Measurement results were compared with the activity values measured by gamma spectrometry. For each source, they agree within one standard uncertainty and also agree within the same limits with the certified values of the source activity. PMID:26701656

  7. System and method for interfacing large-area electronics with integrated circuit devices

    DOEpatents

    Verma, Naveen; Glisic, Branko; Sturm, James; Wagner, Sigurd

    2016-07-12

    A system and method for interfacing large-area electronics with integrated circuit devices is provided. The system may be implemented in an electronic device including a large area electronic (LAE) device disposed on a substrate. An integrated circuit IC is disposed on the substrate. A non-contact interface is disposed on the substrate and coupled between the LAE device and the IC. The non-contact interface is configured to provide at least one of a data acquisition path or control path between the LAE device and the IC.

  8. [100] or [110] aligned, semiconductor-based, large-area, flexible, electronic devices

    SciTech Connect

    Goyal, Amit

    2015-03-24

    Novel articles and methods to fabricate the same resulting in flexible, large-area, [100] or [110] textured, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  9. Development of large area, low-cost, solar cell processing sequence

    NASA Technical Reports Server (NTRS)

    Chitre, S.; Donon, J.

    1981-01-01

    A cost effective process based on state-of-the-art technology has been developed for the production of large-area (55 sq cm and larger) solar cells. The process is capable of providing silicon and polysilicon cell efficiencies in excess of 10% at an overall cost of 12 c/watt in 1980 dollars. The process provides large throughputs and is suitable for complete automation with high yields. Various stages of the process development are discussed.

  10. Fast and large-area growth of uniform MoS2 monolayers on molybdenum foils.

    PubMed

    Tai, Guoan; Zeng, Tian; Yu, Jin; Zhou, Jianxin; You, Yuncheng; Wang, Xufeng; Wu, Hongrong; Sun, Xu; Hu, Tingsong; Guo, Wanlin

    2016-01-28

    A controllable synthesis of two-dimensional crystal monolayers in a large area is a prerequisite for potential applications, but the growth of transition metal dichalcogenide monolayers in a large area with spatial homogeneity remains a great challenge. Here we report a novel and efficient method to fabricate large-scale MoS2 monolayers by direct sulfurization of pre-annealed molybdenum foil surfaces with large grain boundaries of more than 50 μm in size at elevated temperatures. Continuous MoS2 monolayers can be formed uniformly by sulfurizing the Mo foils in sulfur vapor at 600 °C within 1 min. At a lower temperature even down to 500 °C, uniform MoS2 monolayers can still be obtained but in a much longer sulfurizing duration. It is demonstrated that the formed monolayers can be nondestructively transferred onto arbitrary substrates by removing the Mo foil using diluted ferric chloride solution and can be successfully fabricated into photodetectors. The results show a novel avenue to efficiently fabricate two-dimensional crystals in a large area in a highly controllable way and should have great potential for the development of large-scale applications of two-dimensional crystals in electrophotonic systems. PMID:26743938

  11. A large-scale deforestation experiment: Effects of patch area and isolation on Amazon birds

    USGS Publications Warehouse

    Ferraz, G.; Nichols, J.D.; Hines, J.E.; Stouffer, P.C.; Bierregaard, R.O.; Lovejoy, T.E.

    2007-01-01

    As compared with extensive contiguous areas, small isolated habitat patches lack many species. Some species disappear after isolation; others are rarely found in any small patch, regardless of isolation. We used a 13-year data set of bird captures from a large landscape-manipulation experiment in a Brazilian Amazon forest to model the extinction-colonization dynamics of 55 species and tested basic predictions of island biogeography and metapopulation theory. From our models, we derived two metrics of species vulnerability to changes in isolation and patch area. We found a strong effect of area and a variable effect of isolation on the predicted patch occupancy by birds.

  12. Characterization of large-area reference sources for the calibration of beta-contamination monitors

    NASA Astrophysics Data System (ADS)

    Janßen, H.; Klein, R.

    1996-02-01

    A method has been developed whereby the activity of a large-area reference source for the calibration of beta-contamination monitors can be determined from a series of measured countrates in a suitable detection system as a function of the distance between the surface of the source and the front face of the detector.

  13. Direct patterning and biofunctionalization of a large-area pristine graphene sheet.

    PubMed

    Hong, Daewha; Bae, KiEun; Park, Duckshin; Kim, Houngkyung; Hong, Seok-Pyo; Kim, Mi-Hee; Lee, Bong Soo; Ko, Sangwon; Jeon, Seokwoo; Zheng, Xu; Yun, Wan Soo; Kim, Yang-Gyun; Choi, Insung S; Lee, Jungkyu K

    2015-03-01

    Direct patterning of streptavidin and NIH 3T3 fibroblast cells was successfully achieved over a large-area pristine graphene sheet on Si/SiO2 by aryl azide-based photografting with the conventional UV lithographic technique and surface-initiated, atom transfer radical polymerization of oligo(ethylene glycol) methacrylate. PMID:25488174

  14. Independent Peer Evaluation of the Large Area Crop Inventory Experiment (LACIE): The LACIE Symposium

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Yield models and crop estimate accuracy are discussed within the Large Area Crop Inventory Experiment. The wheat yield estimates in the United States, Canada, and U.S.S.R. are emphasized. Experimental results design, system implementation, data processing systems, and applications were considered.

  15. LARGE AREA LAND COVER MAPPING THROUGH SCENE-BASED CLASSIFICATION COMPOSITING

    EPA Science Inventory

    Over the past decade, a number of initiatives have been undertaken to create definitive national and global data sets consisting of precision corrected Landsat MSS and TM scenes. One important application of these data is the derivation of large area land cover products spanning ...

  16. Large-Area Metasurface Perfect Absorbers from Visible to Near-Infrared.

    PubMed

    Akselrod, Gleb M; Huang, Jiani; Hoang, Thang B; Bowen, Patrick T; Su, Logan; Smith, David R; Mikkelsen, Maiken H

    2015-12-22

    An absorptive metasurface based on film-coupled colloidal silver nanocubes is demonstrated. The metasurfaces are fabricated using simple dip-coating methods and can be deposited over large areas and on arbitrarily shaped objects. The surfaces show nearly complete absorption, good off-angle performance, and the resonance can be tuned from the visible to the near-infrared. PMID:26549512

  17. Methodology for large-area moderate-resolution monitoring of soil organic carbon change

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sequestration of carbon dioxide from the atmosphere into the soil helps to reduce global warming by greenhouse gases and helps to sustain the soil. Methods need to be developed to monitor changes in soil organic carbon over large areas such as the central United States. Direct measurements are acc...

  18. INSTRUCTIONAL PROGRAMS IN SECONDARY SCHOOLS SERVING CONTRASTING SOCIOECONOMIC AREAS IN LARGE CITIES.

    ERIC Educational Resources Information Center

    GOODMAN, THOMAS L.

    A SOURCE OF SPECIFIC INFORMATION WAS DEVELOPED ON INSTRUCTIONAL PROGRAMS IN JUNIOR AND SENIOR HIGH SCHOOLS SERVING CONTRASTING SOCIOECONOMIC AREAS OF SEVEN LARGE CITIES OF THE MIDWESTERN UNITED STATES. THE INFORMATION SOUGHT IN THIS STUDY (GATHERED BY OBSERVATION, INTERVIEW, AND INVENTORY METHODS) FELL INTO TWO CATEGORIES--(1) DATA ABOUT THE…

  19. Homeless Students and Academic Achievement: Evidence from a Large Urban Area

    ERIC Educational Resources Information Center

    Tobin, Kerri J.

    2016-01-01

    Child homelessness has recently reached levels unprecedented in the United States since the Great Depression. Contemporary research has attempted to isolate the effects of homelessness on education, with mixed results. This study reports results from a study in one large urban area and finds that there is no meaningful difference in achievement…

  20. Transformational, Large Area Fabrication of Nanostructured Materials Using Plasma Arc Lamps

    SciTech Connect

    2009-03-01

    This factsheet describes a study that will address critical additional steps over large areas of as-synthesized nanostructured materials, such as annealing, phase transformation, or activation of dopants, dramatically reducing the processing costs of the solid-state lighting and photovoltaic materials.

  1. Laser interference lithography for large area patterning and the fabrication of functional nanostructures

    NASA Astrophysics Data System (ADS)

    Wathuthanthri, Ishan

    Nature-inspired phenomena such as the "moth eye" and "lotus leaf" effects have gained a lot of interest in recent years due to potential applications in a wide range of scientific and engineering disciplines. To practically achieve a majority of these biomimetic applications it is necessary to fabricate such nano-featured surfaces in a low-cost and high-throughput manner. To this end, this dissertation focuses on developing and using the Interference Lithography (IL) technologies to achieve large-area nanopatterning. IL is a parallel-type nanolithography technique that shares many of the advantages of other parallel-type techniques such as deep-UV photolithography while alleviating a majority of concerns such as cost and complexity. IL relies on the interference of two or more beams of light where the resulting interference fringes are generally recorded on a light sensitive polymeric material such as photoresist. In simple two-beam IL systems, the periodicity of the interference fringes is simply a function of wavelength and the angle of separation of the two beams, while the maximum coverage area is a constrained by the optical path and the exposed area. To this extent, in the design of interferometers for nanopatterning, the challenge remains in designing systems where a simple mechanism exists for varying the angle of separation of the interfering beams and in turn periodicity of the interference fringes while also enabling large-area exposures. To this end, the first half of this dissertation demonstrates three different IL systems (Lloyd-mirror, two-degree-of freedom Lloyd-mirror, and the tunable two-mirror systems) designed and established at Stevens capable of fast tuning of periodicities while also achieving wafer-scale (4") large-area nanopatterning. Using the large-area nanopatterns of photoresist, various pattern transfer techniques have also been investigated where the photoresist film is used as a template layer to transfer the large-area periodic

  2. Transferred large area single crystal MoS2 field effect transistors

    NASA Astrophysics Data System (ADS)

    Lee, Choong Hee; McCulloch, William; Lee, Edwin W.; Ma, Lu; Krishnamoorthy, Sriram; Hwang, Jinwoo; Wu, Yiying; Rajan, Siddharth

    2015-11-01

    Transfer of epitaxial, two-dimensional (2D) MoS2 on sapphire grown via synthetic approaches is a prerequisite for practical device applications. We report centimeter-scale, single crystal, synthesized MoS2 field effect transistors (FETs) transferred onto SiO2/Si substrates, with a field-effect mobility of 4.5 cm2 V-1 s-1, which is among the highest mobility values reported for the transferred large-area MoS2 transistors. We demonstrate simple and clean transfer of large-area MoS2 films using deionized water, which can effectively avoid chemical contamination. The transfer method reported here allows standard i-line stepper lithography process to realize multiple devices over the entire film area.

  3. Toward Large-Area Sub-Arcsecond X-Ray Telescopes

    NASA Technical Reports Server (NTRS)

    O'Dell, Stephen L.; Aldcroft, Thomas L.; Allured, Ryan; Atkins, Carolyn; Burrows, David N.; Cao, Jian; Chalifoux, Brandon D.; Chan, Kai-Wing; Cotroneo, Vincenzo; Elsner, Ronald F.; Graham, Michael E.; Gubarev, Mikhail V.; Heilmann, Ralf K.; Johnson-Wilke, Raegan L.; Kilaru, Kiranmayee; Kolodziejczak, Jeffrey J.; McMuldroch, Stuart; Ramsey, Brian D.; Reid, Paul B.; Riveros, Raul E.; Roche, Jacqueline M.; Saha, Timo T.; Schattenburg, Mark L.; Schwartz, Daniel A.; Trolier-McKinstry, Susan E.; Ulmer, Melville P.; Vaynman, Semyon; Vikhlinin, Alexey; Wang, Xiaoli; Weisskopf, Martin C.; Wilke, Rudeger H. T.; Zhang, William W.

    2014-01-01

    The future of x-ray astronomy depends upon development of x-ray telescopes with larger aperture areas (>1 sq m) and finer angular resolution(<1).Combined with the special requirements of nested grazing incidence optics, the mass and envelope constraints of spaceborne telescopes render such advances technologically challenging. Achieving this goal will require precision fabrication, alignment, mounting, and assembly of large areas (>100 sq m) of lightweight (1 kg/sq m areal density) high quality mirrors-possibly entailing active (in-space adjustable) alignment and figure correction. This paper discusses relevant programmatic and technological issues and summarizes progress toward large area sub-arcsecond x-ray telescopes. Key words: X-ray telescopes, x-ray optics, active optics, electroactive devices, silicon mirrors, differential deposition, ion implantation.

  4. Fast and cost-effective fabrication of large-area plasmonic transparent biosensor array.

    PubMed

    Intartaglia, R; Beke, S; Moretti, M; De Angelis, F; Diaspro, A

    2015-03-01

    Surface enhanced Raman-based sensors are widely used for chemical and biological species analysis; but to date the high cost, long production time, hazardous, and toxic content as well as small sensing area and opacity are limiting their capabilities for widespread applications in the medical and environmental fields. We present a novel cost-effective method for fast laser-based fabrication of affordable large-area and transparent periodic arrays of ligand-free metallic nanoparticles, offering a maximum possibility for the adsorption/immobilization of molecules and labeling. Further, we demonstrate a remarkable detection limit in the picomolar range by means of Raman scattering, thus evidencing a superior signal-to-noise ratio compared to other sensor substrates. The high sensitivity performance along with a fast and cheap fabrication procedure of reusable large-area transparent plasmonic devices opens the route for direct, in situ multimodal optical analysis with broad applications in the biomedical/analytical fields. PMID:25591078

  5. The Anti-Coincidence Detector for the GLAST Large Area Telescope

    SciTech Connect

    Moiseev, A.A.; Hartman, R.C.; Ormes, J.F.; Thompson, D.J.; Amato, M.J.; Johnson, T.E.; Segal, K.N.; Sheppard, D.A.

    2007-03-23

    This paper describes the design, fabrication and testing of the Anti-Coincidence Detector (ACD) for the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT). The ACD is LAT's first-level defense against the charged cosmic ray background that outnumbers the gamma rays by 3-5 orders of magnitude. The ACD covers the top and 4 sides of the LAT tracking detector, requiring a total active area of {approx}8.3 square meters. The ACD detector utilizes plastic scintillator tiles with wave-length shifting fiber readout. In order to suppress self-veto by shower particles at high gamma-ray energies, the ACD is segmented into 89 tiles of different sizes. The overall ACD efficiency for detection of singly charged relativistic particles entering the tracking detector from the top or sides of the LAT exceeds the required 0.9997.

  6. High-intensity terahertz radiation from a microstructured large-area photoconductor

    NASA Astrophysics Data System (ADS)

    Dreyhaupt, A.; Winnerl, S.; Dekorsy, T.; Helm, M.

    2005-03-01

    We present a planar large-area photoconducting emitter for impulsive generation of terahertz (THz) radiation. The device consists of an interdigitated electrode metal-semiconductor-metal (MSM) structure which is masked by a second metallization layer isolated from the MSM electrodes. The second layer blocks optical excitation in every second period of the MSM finger structure. Hence charge carriers are excited only in those periods of the MSM structure which exhibit a unidirectional electric field. Constructive interference of the THz emission from accelerated carriers leads to THz electric field amplitudes up to 85V/cm when excited with fs optical pulses from a Ti:sapphire oscillator with an average power of 100mW at a bias voltage of 65V applied to the MSM structure. The proposed device structure has a large potential for large-area high-power THz emitters.

  7. Large Area Transition Edge Sensor X-ray Microcalorimeters for Diffuse X-ray Background Studies

    NASA Astrophysics Data System (ADS)

    Morgan, K. M.; Busch, S. E.; Eckart, M. E.; Kilbourne, C. A.; McCammon, D.

    2014-08-01

    We are developing transition edge sensor (TES) mirocalorimeters with large area (0.72 mm) absorbers to study the keV diffuse X-ray background. The goal is to develop a 2 cm array of 256 pixels for a sounding rocket payload. We present a pixel design which includes a Mo/Au bilayer TES coupled to a large (850 x 850 x 0.2 m) gold absorber. Our simulations indicate that such a design can achieve energy resolution as good as 1.6 eV FWHM in our target bandpass of 0.05-1 keV. Additionally, thermal modelling shows that for typical gold layers, the position-dependent variation of the pulse shape over the large area of the absorber is not expected to significantly degrade this energy resolution. An array of devices will be fabricated in late 2013 to test this design.

  8. Large abdominal photopenic area on 99mTc-sestamibi myocardial perfusion imaging.

    PubMed

    Lyon, Jennifer; Spaulding, John; Zack, Paul M

    2012-12-01

    (99m)Tc-sestamibi myocardial perfusion imaging is frequently performed in conjunction with exercise or pharmacologic stress testing for evaluation of coronary heart disease. Interpretation of these studies includes systematic review of unprocessed rotating projectional images for evaluation of cardiac size as well as the presence of motion or attenuation artifacts. Occasionally, incidental noncardiac findings are detected on review of the projectional images. We report a case of a patient with a history of autosomal dominant polycystic kidney disease who was found to have a large abdominal photopenic area on the projectional images. The photopenic area corresponded to the location of large intraabdominal cysts on abdominal CT and was consistent with hepatic cysts associated with the patient's known polycystic kidney disease. We review the differential diagnosis of large abdominal photopenic regions identified on myocardial projectional images and the importance of routinely analyzing these images for incidental noncardiac findings. PMID:22997275

  9. A facility for the test of large-area muon chambers at high rates

    NASA Astrophysics Data System (ADS)

    Agosteo, S.; Altieri, S.; Belli, G.; Bonifas, A.; Carabelli, V.; Gatignon, L.; Hessey, N.; Maggi, M.; Peigneux, J.-P.; Reithler, H.; Silari, M.; Vitulo, P.; Wegner, M.

    2000-09-01

    Operation of large-area muon detectors at the future Large Hadron Collider (LHC) will be characterized by large sustained hit rates over the whole area, reaching the range of kHz cm -2. We describe a dedicated test zone built at CERN to test the performance and the aging of the muon chambers currently under development. A radioactive source delivers photons causing the sustained rate of random hits, while a narrow beam of high-energy muons is used to directly calibrate the detector performance. A system of remotely controlled lead filters serves to vary the rate of photons over four orders of magnitude, to allow the study of performance as a function of rate.

  10. Degenerate four wave mixing in large mode area hybrid photonic crystal fibers.

    PubMed

    Petersen, Sidsel R; Alkeskjold, Thomas T; Lægsgaard, Jesper

    2013-07-29

    Spontaneous degenerate four wave mixing (FWM) is investigated in large mode area hybrid photonic crystal fibers, in which photonic bandgap guidance and index guidance is combined. Calculations show the parametric gain is maximum on the edge of a photonic bandgap, for a large range of pump wavelengths. The FWM products are observed on the edges of a transmission band experimentally, in good agreement with the numerical results. Thereby the bandedges can be used to control the spectral positions of FWM products through a proper fiber design. The parametric gain control combined with a large mode area fiber design potentially allows for power scaling of light at wavelengths not easily accessible with e.g. rare earth ions. PMID:23938682

  11. Meter-Scale Large-Area Plasma Sources for Next-Generation Processes

    NASA Astrophysics Data System (ADS)

    Setsuhara, Yuichi

    Development of large-area high-density plasma sources with a scale length of meters is strongly desired for a variety of plasma processes, especially the flat panel display fabrications. Considering design issues for plasma production with high-frequency power sources to satisfy the requirements for enlargement of source-size exceeding a meter, the power deposition profile and hence the plasma distribution become inherently non-uniform, largely due to standing wave effects, which cannot be avoided with increasing source size when the source employs power-coupling devices (inductive antennas or capacitive electrodes) with a scale-length equivalent to or as long as the 1/4 wavelength of the HF-power transmission. In this article, these constraints associated with large-area sources are reviewed, and an inductively coupled RF plasma source with multiple low-inductance antenna (LIA) units is presented as a promising candidate to avoid the problems with conventional sources.

  12. Large-Area Synthesis of High-Quality Uniform Few-Layer MoTe2.

    PubMed

    Zhou, Lin; Xu, Kai; Zubair, Ahmad; Liao, Albert D; Fang, Wenjing; Ouyang, Fangping; Lee, Yi-Hsien; Ueno, Keiji; Saito, Riichiro; Palacios, Tomás; Kong, Jing; Dresselhaus, Mildred S

    2015-09-23

    The controlled synthesis of large-area, atomically thin molybdenum ditelluride (MoTe2) crystals is crucial for its various applications based on the attractive properties of this emerging material. In this work, we developed a chemical vapor deposition synthesis to produce large-area, uniform, and highly crystalline few-layer 2H and 1T' MoTe2 films. It was found that these two different phases of MoTe2 can be grown depending on the choice of Mo precursor. Because of the highly crystalline structure, the as-grown few-layer 2H MoTe2 films display electronic properties that are comparable to those of mechanically exfoliated MoTe2 flakes. Our growth method paves the way for the large-scale application of MoTe2 in high-performance nanoelectronics and optoelectronics. PMID:26305492

  13. Very Large Area/Volume Microwave ECR Plasma and Ion Source

    NASA Technical Reports Server (NTRS)

    Foster, John E. (Inventor); Patterson, Michael J. (Inventor)

    2009-01-01

    The present invention is an apparatus and method for producing very large area and large volume plasmas. The invention utilizes electron cyclotron resonances in conjunction with permanent magnets to produce dense, uniform plasmas for long life ion thruster applications or for plasma processing applications such as etching, deposition, ion milling and ion implantation. The large area source is at least five times larger than the 12-inch wafers being processed to date. Its rectangular shape makes it easier to accommodate to materials processing than sources that are circular in shape. The source itself represents the largest ECR ion source built to date. It is electrodeless and does not utilize electromagnets to generate the ECR magnetic circuit, nor does it make use of windows.

  14. Large-area high-quality graphene on Ge(001)/Si(001) substrates.

    PubMed

    Pasternak, I; Dabrowski, P; Ciepielewski, P; Kolkovsky, V; Klusek, Z; Baranowski, J M; Strupinski, W

    2016-06-01

    Various experimental data revealing large-area high-quality graphene films grown by the CVD method on Ge(001)/Si(001) substrates are presented. SEM images have shown that the structure of nano-facets is formed on the entire surface of Ge(001), which is covered by a graphene layer over the whole macroscopic sample surface of 1 cm(2). The hill-and-valley structures are positioned 90° to each other and run along the <100> direction. The hill height in relation to the valley measured by STM is about 10 nm. Raman measurements have shown that a uniform graphene monolayer covers the nano-facet structures on the Ge(001) surface. Raman spectroscopy has also proved that the grown graphene monolayer is characterized by small strain variations and minimal charge fluctuations. Atomically resolved STM images on the hills of the nanostructures on the Ge(001) surface have confirmed the presence of a graphene monolayer. In addition, the STS/CITS maps show that high-quality graphene has been obtained on such terraces. The subsequent coalescence of graphene domains has led to a relatively well-oriented large-area layer. This is confirmed by LEED measurements, which have indicated that two orientations are preferable in the grown large-area graphene monolayer. The presence of large-area coverage by graphene has been also confirmed by low temperature Hall measurements of a macroscopic sample, showing an n-type concentration of 9.3 × 10(12) cm(-2) and a mobility of 2500 cm(2) V(-1) s(-1). These important characteristic features of graphene indicate a high homogeneity of the layer grown on the large area Ge(001)/Si(001) substrates. PMID:27189131

  15. Large-area high-quality graphene on Ge(001)/Si(001) substrates

    NASA Astrophysics Data System (ADS)

    Pasternak, I.; Dabrowski, P.; Ciepielewski, P.; Kolkovsky, V.; Klusek, Z.; Baranowski, J. M.; Strupinski, W.

    2016-05-01

    Various experimental data revealing large-area high-quality graphene films grown by the CVD method on Ge(001)/Si(001) substrates are presented. SEM images have shown that the structure of nano-facets is formed on the entire surface of Ge(001), which is covered by a graphene layer over the whole macroscopic sample surface of 1 cm2. The hill-and-valley structures are positioned 90° to each other and run along the <100> direction. The hill height in relation to the valley measured by STM is about 10 nm. Raman measurements have shown that a uniform graphene monolayer covers the nano-facet structures on the Ge(001) surface. Raman spectroscopy has also proved that the grown graphene monolayer is characterized by small strain variations and minimal charge fluctuations. Atomically resolved STM images on the hills of the nanostructures on the Ge(001) surface have confirmed the presence of a graphene monolayer. In addition, the STS/CITS maps show that high-quality graphene has been obtained on such terraces. The subsequent coalescence of graphene domains has led to a relatively well-oriented large-area layer. This is confirmed by LEED measurements, which have indicated that two orientations are preferable in the grown large-area graphene monolayer. The presence of large-area coverage by graphene has been also confirmed by low temperature Hall measurements of a macroscopic sample, showing an n-type concentration of 9.3 × 1012 cm-2 and a mobility of 2500 cm2 V-1 s-1. These important characteristic features of graphene indicate a high homogeneity of the layer grown on the large area Ge(001)/Si(001) substrates.

  16. Large area chemical vapor deposition of monolayer transition metal dichalcogenides and their temperature dependent Raman spectroscopy studies.

    PubMed

    Pawbake, Amit S; Pawar, Mahendra S; Jadkar, Sandesh R; Late, Dattatray J

    2016-02-01

    We investigate the growth mechanism and temperature dependent Raman spectroscopy of chemical vapor deposited large area monolayer of MoS2, MoSe2, WS2 and WSe2 nanosheets up to 70 μm in lateral size. Further, our temperature dependent Raman spectroscopy investigation shows that softening of Raman modes as temperature increases from 80 K to 593 K is due to the negative temperature coefficient and anharmonicity. The temperature dependent softening modes of chemical vapor deposited monolayers of all TMDCs were explained on the basis of a double resonance phonon process which is more active in an atomically thin sample. This process can also be fundamentally pertinent in other emerging two-dimensional layered and heterostructured materials. PMID:26782944

  17. Large area chemical vapor deposition of monolayer transition metal dichalcogenides and their temperature dependent Raman spectroscopy studies

    NASA Astrophysics Data System (ADS)

    Pawbake, Amit S.; Pawar, Mahendra S.; Jadkar, Sandesh R.; Late, Dattatray J.

    2016-01-01

    We investigate the growth mechanism and temperature dependent Raman spectroscopy of chemical vapor deposited large area monolayer of MoS2, MoSe2, WS2 and WSe2 nanosheets up to 70 μm in lateral size. Further, our temperature dependent Raman spectroscopy investigation shows that softening of Raman modes as temperature increases from 80 K to 593 K is due to the negative temperature coefficient and anharmonicity. The temperature dependent softening modes of chemical vapor deposited monolayers of all TMDCs were explained on the basis of a double resonance phonon process which is more active in an atomically thin sample. This process can also be fundamentally pertinent in other emerging two-dimensional layered and heterostructured materials.We investigate the growth mechanism and temperature dependent Raman spectroscopy of chemical vapor deposited large area monolayer of MoS2, MoSe2, WS2 and WSe2 nanosheets up to 70 μm in lateral size. Further, our temperature dependent Raman spectroscopy investigation shows that softening of Raman modes as temperature increases from 80 K to 593 K is due to the negative temperature coefficient and anharmonicity. The temperature dependent softening modes of chemical vapor deposited monolayers of all TMDCs were explained on the basis of a double resonance phonon process which is more active in an atomically thin sample. This process can also be fundamentally pertinent in other emerging two-dimensional layered and heterostructured materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07401k

  18. Preparation of activated carbon with large specific surface area from reed black liquor.

    PubMed

    Sun, Y; Zhang, J P; Yang, G; Li, Z H

    2007-05-01

    Activated carbon with large specific surface area and well-developed porosity was prepared from pyrolysis of K2CO3-impregnated lignin precipitated from reed pulp black liquors. The impregnation ratio was 1:1. The effect of activation temperature upon the Brunauer-Emmett-Teller (BET) specific surface area and pore volume of the carbon was closely investigated. Increasing activation temperature led to an opening and widening of the porous structure below 800'C. Above 800'C, the excess widening of pore led to the decrease of BET surface area and micropore volume. The BET surface area and pore volume of the carbon activated at 800 degrees C were 1395 m(2) g(-1) and 0.7702 ml g(-1) , respectively. The potential application of the carbon activated at 800 degrees C for removal of Cr (VI) was also investigated. The experimental results showed that it had good adsorption capacity. PMID:17615958

  19. Simplified graphical tools for assessing flood-risk change over large flood-prone areas

    NASA Astrophysics Data System (ADS)

    Carisi, F.; Domeneghetti, A.; Castellarin, A.

    2015-06-01

    We propose and investigate the reliability of simplified graphical tools, which we term Hypsometric Vulnerability Curves, HVCs, for assessing flood vulnerability and risk over large geographical areas and for defining sustainable flood-risk mitigation strategies. These curves rely on the use of inundation scenarios simulated by means of quasi-two-dimensional (quasi-2-D) hydrodynamic models that reproduce the hydraulic behaviour of the floodable area outside the main embankment system of the study river reach. We present an application of HVCs constructed on the basis of land use and census data collected during the last 50 years for assessing the recent dynamics of the flood vulnerability and risk over a large floodable area along a 350 km stretch of the River Po (Northern Italy). We also compared the proposed simplified approach with a traditional approach based on simulations performed with the fully-2-D hydrodynamic model TELEMAC-2-D, a widely employed and well-known 2-D finite-element scheme. By means of this comparison, we characterize the accuracy of the proposed simplified approach (i.e. quasi-2-D model and HVCs) for flood-risk assessment over large geographical areas and different historical land-use scenarios.

  20. Design, Production and Testing of Cost-Effective, Large-Area, MCP-based Planar Photodetectors

    NASA Astrophysics Data System (ADS)

    Xie, Junqi; Byrum, Karen; Demarteau, Marcel; Noonan, John; Setru, Sagar; Virgo, Mathew; Wagner, Robert; Walters, Dean; Wang, Xing; Xia, Lei; Zhao, Huyue

    2014-03-01

    Microchannel plate (MCP)-based photodetectors with large-area, thin planar geometry and glass-body assembly, are considered as next generation photodetector to replace photomultiplier tubes. They have shown significant potential for applications in high energy collider physics and astrophysics. Due to the extreme sensitivity of the photocathode to water and oxygen, the production of this kind of photodetectors requires photocathodes to be transferred under high vacuum. A new photodetector production facility at Argonne National Laboratory was designed and constructed. The facility aims to produce small form-factor, MCP-based photodetectors completely made out of glass. 6 x 6 cm2 photodetectors using metal and alkali antimonide as photocathode are currently under production. An overview of the production sequence and first performance results will be presented. Scaling up the production to larger form-factor devices will be discussed. The challenge of sealing a large area photodetector has recently been overcome. Windows with 20 × 20 cm2 active photocathode area were successfully sealed and progress towards large-area photodetector production progress will be reported.

  1. A novel lithography technique for formation of large areas of uniform nanostructures

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Dey, Dibyendu; Memis, Omer G.; Katsnelson, Alex; Mohseni, Hooman

    2008-08-01

    With nanotechnology becoming widely used, many applications such as plasmonics, sensors, storage devices, solar cells, nano-filtration and artificial kidneys require the structures with large areas of uniform periodic nanopatterns. Most of the current nano-manufacturing techniques, including photolithography, electron-beam lithography, and focal ion beam milling, are either slow or expensive to be applied into the areas. Here, we demonstrate an alternative and novel lithography technique - Nanosphere Photolithography (NSP) - that generates a large area of highly uniform periodic nanoholes or nanoposts by utilizing the monolayer of hexagonally close packed (HCP) silica microspheres as super-lenses on top of photoresist. The size of the nanopatterns generated is almost independent of the sphere sizes and hence extremely uniform patterns can be obtained. We demonstrate that the method can produce hexagonally packed arrays of hole of sub-250 nm size in positive photoresist using a conventional exposure system with a broadband UV source centered at 400 nm. We also show a large area of highly uniform gold nanoholes (~180 nm) and nanoposts (~300nm) array with the period of 1 μm fabricated by the combination of lift-off and NSP. The process is not limited to gold. Similar structures have been shown with aluminum and silicon dioxide layer. The period and size of the structures can also be tuned by changing proper parameters. The technique applying self-assembled and focusing properties of micro-/nano-spheres into photolithography establishes a new paradigm for mask-less photolithography technique, allowing rapid and economical creation of large areas of periodic nanostructures with a high throughput.

  2. Two-group interfacial area transport equation in large diameter pipes

    NASA Astrophysics Data System (ADS)

    Smith, Todd Ryan

    2002-01-01

    The closure relations for the two-group interfacial area transport equation (LATE) by which the changes of interfacial area concentration can be dynamically modeled are set forth in this thesis for the case of large diameter pipes. In the two-group formulation, the sources and sink terms are established by mechanistic modeling of the intra-group and inter-group transport of the bubbles based on five major bubble interaction mechanisms. These mechanisms are bubble coalescence as a result of random collision, RC, wake entrainment, WE, bubble break-up due to turbulent impact, TI, small bubble shearing-off of large bubbles, SO, and bubble break-up due to surface instability for large bubbles, SI. The models developed are supported by experiments using a four-sensor conductivity probe in large diameter test sections, 10.16 cm and 15.24 cm in diameter. A total of 31 different flow conditions under atmospheric pressure are examined in the bubbly to churn-turbulent flow regimes. The local flow parameters measured by the multi-sensor conductivity probe include the local time-averaged void fraction, interfacial area concentration, bubble Sauter mean diameter, interfacial velocity, and interface frequency for the two groups of bubbles. The model is evaluated against the extensive database and good agreement is obtained between the model predictions and the experimental data. The average error based on the total interfacial area concentration is around 7.0% for interfacial area concentration in both test sections. Recirculation in the large pipes is given special treatment in the measurement analysis. Using upwards and downwards facing probes, information on the missing bubble signals is obtained which is used to correct the local data by either the Effective Bubble Number or Intrusiveness Factor Method. The correction to void fraction is found to be about a 12% increase in the local area averaged value, while interfacial area concentration may increase upwards of 60% in the

  3. Fabrication of stable, large-area thin-film CdTe photovoltaic modules

    NASA Astrophysics Data System (ADS)

    Zhou, T. X.

    1995-06-01

    During the period of this subcontract, May 1991 through February 1995, Solar Cells, Inc. has developed and demonstrated a low-cost process to fabricate stable large-area cadmium telluride based thin-film photovoltaic modules. This report summarizes the final phase of the project which is concentrated on process optimization and product life tests. One of the major post-deposition process steps, the CdCl2 heat treatment, has been experimentally replaced with alternative treatments with vapor chloride or chlorine gas. Material and device qualities associated with alternative treatments are comparable or superior to those with the conventional treatment. Extensive experiments have been conducted to optimize the back-electrode structure in order to ensure long term device stability. Numerous small-area cells and minimodules have been subjected to a variety of stress tests, including but not limited to continuous light soak under open or short circuit or with resistive load, for over 10,000 hours. Satisfactory stability has been demonstrated on 48 and 64 sq cm minimodules under accelerated tests and on 7200 sq cm large modules under normal operating conditions. The conversion efficiency has also been significantly improved during this period. The total area efficiency of 7200 sq cm module has reached 8.4%, corresponding to a 60.3 W normalized output; the efficiency of 64 sq cm minimodules and 1.1 sq cm cells has reached 10.5% (aperture area) and 12.4% (total area), respectively.

  4. Recalibration of cumulative rainfall estimates by weather radar over a large area

    NASA Astrophysics Data System (ADS)

    Mazza, Alessandro; Antonini, Andrea; Melani, Samantha; Ortolani, Alberto

    2015-01-01

    The real-time measurement of rainfall is a primary information source for many purposes, such as weather forecasting, flood risk assessment, and landslide prediction and prevention. In this perspective, remote sensing techniques to monitor rainfall fields by means of radar measurements are very useful. In this work, a technique is proposed for the estimation of cumulative rainfall fields averaged over a large area, applied on the Tuscany region using the Italian weather radar network. In order to assess the accuracy of radar-based rainfall estimates, they are compared with coincident spatial rain gauge measurements. Observations are compared with average rainfall over areas as large as a few tens of kilometers. An ordinary block kriging method is applied for rain gauge data spatialization. The comparison between the two types of estimates is used for recalibrating the radar measurements. As a main result, this paper proposes a recalibrated relationship for retrieving precipitation from radar data. The accuracy of the estimate increases when considering larger areas: an area of 900 km2 has a standard deviation of less than few millimeters. This is of interest in particular for extending recalibrated radar relationships over areas where rain gauges are not available. Many applications could benefit from it, from nowcasting for civil protection activities, to hydrogeological risk mitigation or agriculture.

  5. Study of the LAT PSF of the Gamma Ray Large Area Telescope

    SciTech Connect

    Cecchi, C.; Germani, S.; Pepe, M.; Bonamente, E.; Ciprini, S.; Lubrano, P.; Tosti, G.

    2007-07-12

    GLAST is the next generation telescope for the study of the Gamma Ray Universe. The GLAST mission is composed of two instruments: the LAT (Large Area Telescope) exploring the energy range between 20 MeV and 300 GeV and the GBM (Gamma ray Burst Monitor) studying the region from 10 KeV up to 30 MeV.GLAST represents an important step beyond EGRET providing a large improvement in instrument performance: large Field of View (FOV), large energy range extending to unexplored region of energies larger than 10 GeV, large effective area, a factor of 30 improvement in sensitivity, a much smaller dead time and a very good Point Spread Function (PSF).Since GLAST will operate in a continuous scanning mode, for most of the time during the mission, photons from a source will be detected at different angles in the LAT field of view requiring a good PSF in order to disentangle between sources.We will present results on PSF studies performed with various sets of data. The selection criteria and algorithm have been initially developed on DC1 and DC2 data (simulation of one and 55 days respectively of data collected by the LAT), applied to the data collected with the 16 LAT towers during the I and T integration phase with cosmic ray muons and finally applied to the testbeam data collected in August 2006 at the CERN beam line.

  6. Applying Bronfenbrenner's Ecological Model to Identify the Negative Influences Facing Children with Physical Disabilities in Rural Areas in Kwa-Zulu Natal

    ERIC Educational Resources Information Center

    Ben-David, Brenda; Nel, Norma

    2013-01-01

    Children with visible physical disabilities (CWPDs) living in rural areas of South Africa are a matter of particular concern. While all children living in rural areas face negative influences such as poverty and the high incidence of HIV/AIDS, this situation is exacerbated for CWPDs who are more vulnerable to these influences (Human Sciences…

  7. Large Area Microcorrals and Cavity Formation on Cantilevers using a Focused Ion Beam

    SciTech Connect

    Saraf, Laxmikant V.; Britt, David W.

    2011-09-14

    We utilize focused ion beam (FIB) to explore various sputtering parameters to form large area microcorrals and cavities on cantilevers. Microcorrals were rapidly created by modifying ion beam blur and overlaps. Modification in FIB sputtering parameters affects the periodicity and shape of corral microstructure. Cantilever deflections show ion beam amorphization effects as a function of sputtered area and cantilever base cavities with or without side walls. The FIB sputtering parameters address a method for rapid creation of a cantilever tensiometer with integrated fluid storage and delivery.

  8. A large-area microstrip-gas-counter for X-ray astronomy

    NASA Astrophysics Data System (ADS)

    Ramsey, B. D.; Apple, J. A.; Austin, R. A.; Dietz, K. L.; Minamitani, T.; Kolodziejczak, J. J.; Weisskopf, M. C.

    1996-02-01

    We have developed a large-area coded-mask telescope for hard-X-ray astronomy. The heart of the instrument is an imaging microstrip-gas-counter of active area 30 cm × 30 cm and filled with 2 × 105 Pa of xenon + 2% isobutylene. Fabricated on a single sheet of borosilicate glass, 1 mm thick, the microstrip features fine anodes (10 μm) and interleaved cathodes from which the position sensing is derived. Rear pickup electrodes provide the second coordinate. Full details of the instrument and its performance are presented. A first flight, from a high-altitude balloon, is scheduled for the Spring of 1977.

  9. Evaluation of large area crop estimation techniques using LANDSAT and ground-derived data. [Missouri

    NASA Technical Reports Server (NTRS)

    Amis, M. L.; Lennington, R. K.; Martin, M. V.; Mcguire, W. G.; Shen, S. S. (Principal Investigator)

    1981-01-01

    The results of the Domestic Crops and Land Cover Classification and Clustering study on large area crop estimation using LANDSAT and ground truth data are reported. The current crop area estimation approach of the Economics and Statistics Service of the U.S. Department of Agriculture was evaluated in terms of the factors that are likely to influence the bias and variance of the estimator. Also, alternative procedures involving replacements for the clustering algorithm, the classifier, or the regression model used in the original U.S. Department of Agriculture procedures were investigated.

  10. Coatings for large-area low-cost solar concentrators and reflectors

    NASA Astrophysics Data System (ADS)

    Martin, Peter M.; Affinito, John D.; Gross, Mark E.; Bennett, Wendy D.

    1994-09-01

    Large-optics coating facilities and processes at Pacific Northwest Laboratory (PNL) that were used to develop large-area high-performance laser mirrors for SDIO are now being used to fabricate a variety of optical components for commercial clients, and for novel applications for other DoD clients. Emphasis of this work is on technology transfer of low-cost coating processes and equipment to private clients. Much of the technology transfer is being accomplished through the CRADA (Cooperative Research and Development Agreement) process funded by the Department of Energy (DOE).

  11. Large-Area Atom Interferometry with Frequency-Swept Raman Adiabatic Passage.

    PubMed

    Kotru, Krish; Butts, David L; Kinast, Joseph M; Stoner, Richard E

    2015-09-01

    We demonstrate light-pulse atom interferometry with large-momentum-transfer atom optics based on stimulated Raman transitions and frequency-swept adiabatic rapid passage. Our atom optics have produced momentum splittings of up to 30 photon recoil momenta in an acceleration-sensitive interferometer for laser cooled atoms. We experimentally verify the enhancement of phase shift per unit acceleration and characterize interferometer contrast loss. By forgoing evaporative cooling and velocity selection, this method lowers the atom shot-noise-limited measurement uncertainty and enables large-area atom interferometry at higher data rates. PMID:26382675

  12. Procedures and results of the measurements on large area photomultipliers for the NEMO project

    NASA Astrophysics Data System (ADS)

    Aiello, S.; Leonora, E.; Aloisio, A.; Ameli, F.; Amore, I.; Anghinolfi, M.; Anzalone, A.; Barbarino, G.; Barbarito, E.; Battaglieri, M.; Bazzotti, M.; Bellotti, R.; Bersani, A.; Beverini, N.; Biagi, S.; Bonori, M.; Bouhdaef, B.; Cacopardo, G.; Calı, C.; Capone, A.; Caponetto, L.; Carminati, G.; Cassano, B.; Ceres, A.; Chiarusi, T.; Circella, M.; Cocimano, R.; Coniglione, R.; Cordelli, M.; Costa, M.; D'Amico, A.; DeBonis, G.; DeRosa, G.; DeRuvo, G.; DeVita, R.; Distefano, C.; Flaminio, V.; Fratini, K.; Gabrielli, A.; Galeotti, S.; Gandolfi, E.; Giacomelli, G.; Giorgi, F.; Giovanetti, G.; Grimaldi, A.; Grmek, A.; Habel, R.; Imbesi, M.; Lonardo, A.; LoPresti, D.; Lucarelli, F.; Margiotta, A.; Marinelli, A.; Martini, A.; Masullo, R.; Maugeri, F.; Migneco, E.; Minutoli, S.; Mongelli, M.; Morganti, M.; Musico, P.; Musumeci, M.; Orlando, A.; Osipenko, M.; Papaleo, R.; Pappalardo, V.; Piattelli, P.; Piombo, D.; Raffaelli, F.; Raia, G.; Randazzo, N.; Reito, S.; Ricco, G.; Riccobene, G.; Ripani, M.; Rovelli, A.; Ruppi, M.; Russo, G. V.; Russo, S.; Sapienza, P.; Sedita, M.; Shirokov, E.; Simeone, F.; Sciliberto, D.; Sipala, V.; Sollima, C.; Spurio, M.; Stefani, F.; Taiuti, M.; Terreni, G.; Trasatti, L.; Urso, S.; Vecchi, M.; Vicini, P.; Wischnewski, R.

    2010-03-01

    The selection of the photomultiplier plays a crucial role in the R&D activity related to a large-scale underwater neutrino telescope. This paper illustrates the main procedures and facilities used to characterize the performances of 72 large area photomultipliers, Hamamatsu model R7081 sel. The voltage to achieve a gain of 5×10 7, dark count rate and single photoelectron time and charge properties of the overall response were measured with a properly attenuated 410 nm pulsed laser. A dedicated study of the spurious pulses was also performed. The results prove that the photomultipliers comply with the general requirements imposed by the project.

  13. Reinforced Epoxy Nanocomposite Sheets Utilizing Large Interfacial Area from a High Surface Area Single-Walled Carbon Nanotube Scaffold

    NASA Astrophysics Data System (ADS)

    Kobashi, Kazufumi; Nishino, Hidekazu; Yamada, Takeo; Futaba, Don; Yumura, Motoo; Hata, Kenji

    2011-03-01

    We employed single-walled carbon nanotubes (SWNTs) with the available highest specific surface area (more than 1000 m2/g) that provided very large interfacial area for the matrix to fabricate epoxy composite sheets. Through mechanical redirection of the SWNT alignment to horizontal to create a laterally aligned scaffold sheet, into which epoxy resin was impregnated. The SWNT scaffold was engineered in structure to meet the these two nearly mutually exclusive demands, i.e. to have nanometer meso-pores (2-50 nm) to facilitate homogeneous impregnation of the epoxy resin and to have mechanical strength to tolerate the compaction forces generated during impregnation. Through this approach, a SWNT/epoxy composite sheet with a nearly ideal morphology was realized where long and aligned SWNTs were loaded at high weight fraction (33 percent) with an intertube distance approaching the radius of gyration for polymers. The resultant composite showed a Young's modulus of 15.0 GPa and a tensile strength of 104 MPa, thus achieving 5.4 and 2.1 times reinforcement as compared to the neat epoxy resin.

  14. Preparation of large-area double-walled carbon nanotube films and application as film heater

    NASA Astrophysics Data System (ADS)

    Wu, Zi Ping; Wang, Jian Nong

    2009-11-01

    Large-area (larger than 30×30 cm 2) double-walled carbon nanotube (DWCNT) films are prepared and application as a heating element for film heaters is demonstrated. A high heating efficiency is observed. Measurements indicate that the use of the DWCNT film heater would save energy consumption up to 20-30% when compared with a commercial film-like metal-based heater. Morphological analysis reveals that the special surface structure, appropriate electric and high thermal conductivities of the film formed by the network of entangled nanotube bundles may lead to the high heating performance. Considering large-area, shape flexibility, negligible weight and easy manipulation, the film exhibits promising potential applications as a film heater for thermal control in aircrafts, medical equipment, home appliances and other industrial fields at low temperature (below 400 °C).

  15. Large-area fabrication of 3D petal-like nanopattern for surface enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Zhou, Weimin; Wang, Jinhe; Zhang, Jing; Li, Xiaoli; Min, Guoquan

    2014-06-01

    A very easy and flexible approach to fabricate large area, petal-like nanopattern for surface enhanced Raman scattering using soft imprint lithography are presented here. The morphology of the petal-like nanopattern can be transferred truly using the h-PDMS and diluted PMMA molding template. By means of Au metal deposition, a SERS substrate with high enhancement factor over large area, which is still a problem, was produced easily. The morphology and Raman enhancement effect of the 3D nanopattern are characterized by SEM, AFM and SERS. The results show that the petal-like 3D nanopattern has high SERS enhancement factor (order of 1.0 × 108) and could be a promising low cost and high performance SERS active substrate.

  16. Performance of the Anti-Coincidence Detector on the GLAST Large Area Telescope

    SciTech Connect

    Thompson, D.J.; Charles, E.; Hartman, R.C.; Moiseev, A.A.; Ormes, J.F.; /NASA, Goddard /Denver U.

    2007-10-22

    The Anti-Coincidence Detector (ACD), the outermost detector layer in the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT), is designed to detect and veto incident cosmic ray charged particles, which outnumber cosmic gamma rays by 3-4 orders of magnitude. The challenge in ACD design is that it must have high (0.9997) detection efficiency for singly-charged relativistic particles, but must also have a low probability for self-veto of high-energy gammas by backsplash radiation from interactions in the LAT calorimeter. Simulations and tests demonstrate that the ACD meets its design requirements. The performance of the ACD has remained stable through stand-alone environmental testing, shipment across the U.S., installation onto the LAT, shipment back across the U.S., LAT environmental testing, and shipment to Arizona. As part of the fully-assembled GLAST observatory, the ACD is being readied for final testing before launch.

  17. Extraordinary suppression of carrier scattering in large area graphene oxide films

    SciTech Connect

    Negishi, R. Kobayashi, Y.

    2014-12-22

    In this study, we find that thermal treatment in ethanol vapor has a remarkable suppression effect of carrier scattering occurring between reduced graphene oxide (rGO) flakes in large area films. We observe excellent electrical properties such as high carrier mobility (∼5 cm{sup 2}/Vs) and low sheet resistance (∼40 KΩ/□) for the rGO films. From the electrical conductivity analysis of large area rGO films using two-dimensional variable range hopping model and structural analysis using Raman spectra measured from the rGO films, we reveal that the significant effect is caused by the expansion of conjugated π-electron system in rGO flake due to the efficient restoration of graphitic structure.

  18. Seeded on-surface supramolecular growth for large area conductive donor-acceptor assembly.

    PubMed

    Goudappagouda; Chithiravel, Sundaresan; Krishnamoorthy, Kothandam; Gosavi, Suresh W; Babu, Sukumaran Santhosh

    2015-07-01

    Charge transport features of organic semiconductor assemblies are of paramount importance. However, large-area extended supramolecular structures of donor-acceptor combinations with controlled self-assembly pathways are hardly accessible. In this context, as a representative example, seeded on-surface supramolecular growth of tetrathiafulvalene and tetracyano-p-quinodimethane (TTF-TCNQ) using active termini of solution-formed sheaves has been introduced to form an extended assembly. We demonstrate for the first time, the creation of a large-area donor-acceptor assembly on the surface, which is practically very tedious, using a seeded, evaporation-assisted growth process. The excellent molecular ordering in this assembly is substantiated by its good electrical conductivity (~10⁻² S cm⁻¹). The on-surface assembly via both internally formed and externally added sheaf-like seeds open new pathways in supramolecular chemistry and device applications. PMID:26036616

  19. Large-Area Binary Blazed Grating Coupler between Nanophotonic Waveguide and LED

    PubMed Central

    Zhou, Wenqian; Zhang, Meiling; Liu, Yu; Zhang, Cheng; Li, Enbang; Miao, Changyun; Tang, Chunxiao

    2014-01-01

    A large-area binary blazed grating coupler for the arrayed waveguide grating (AWG) demodulation integrated microsystem on silicon-on-insulator (SOI) was designed for the first time. Through the coupler, light can be coupled into the SOI waveguide from the InP-based C-band LED for the AWG demodulation integrated microsystem to function. Both the length and width of the grating coupler are 360 μm, as large as the InP-based C-band LED light emitting area in the system. The coupler was designed and optimized based on the finite difference time domain method. When the incident angle of the light source is 0°, the coupling efficiency of the binary blazed grating is 40.92%, and the 3 dB bandwidth is 72 nm at a wavelength of 1550 nm. PMID:25126602

  20. Electronic sensor and actuator webs for large-area complex geometry cardiac mapping and therapy

    PubMed Central

    Kim, Dae-Hyeong; Ghaffari, Roozbeh; Lu, Nanshu; Wang, Shuodao; Lee, Stephen P.; Keum, Hohyun; D’Angelo, Robert; Klinker, Lauren; Su, Yewang; Lu, Chaofeng; Kim, Yun-Soung; Ameen, Abid; Li, Yuhang; Zhang, Yihui; de Graff, Bassel; Hsu, Yung-Yu; Liu, ZhuangJian; Ruskin, Jeremy; Xu, Lizhi; Lu, Chi; Omenetto, Fiorenzo G.; Huang, Yonggang; Mansour, Moussa; Slepian, Marvin J.; Rogers, John A.

    2012-01-01

    Curved surfaces, complex geometries, and time-dynamic deformations of the heart create challenges in establishing intimate, nonconstraining interfaces between cardiac structures and medical devices or surgical tools, particularly over large areas. We constructed large area designs for diagnostic and therapeutic stretchable sensor and actuator webs that conformally wrap the epicardium, establishing robust contact without sutures, mechanical fixtures, tapes, or surgical adhesives. These multifunctional web devices exploit open, mesh layouts and mount on thin, bio-resorbable sheets of silk to facilitate handling in a way that yields, after dissolution, exceptionally low mechanical moduli and thicknesses. In vivo studies in rabbit and pig animal models demonstrate the effectiveness of these device webs for measuring and spatially mapping temperature, electrophysiological signals, strain, and physical contact in sheet and balloon-based systems that also have the potential to deliver energy to perform localized tissue ablation. PMID:23150574

  1. Large-area chromogenics: Materials and devices for transmittance control. Volume IS 4

    SciTech Connect

    Lampert, C.M.; Granqvist, C.G.

    1990-12-31

    Chromogenic materials can alter their optical properties in a persistent yet reversible manner when subjected to a change in external conditions such as irradiation intensity, temperature, or electric-field strength. In the future chromogenic materials may be used on large scale to regulate the throughput of radiant energy for windows in buildings and cars, so that comfortable lighting and temperature are maintained without excessive air conditioning. The purpose of this book is to give a broad coverage of large-area chromogenics and to discuss their applications. The book is divided into the following areas: applications; photochromic materials; thermochromic materials; inorganic electrochromic materials; inorganic electrochromic materials; organic electrochromic materials; conductors for ions and electrons in electrochromic devices; electrochromic devices; and liquid crystals materials and devices. Separate abstracts were prepared for 33 papers in this book.

  2. Catalytic Growth of Graphene: Toward Large-Area Single-Crystalline Graphene.

    PubMed

    Ago, Hiroki; Ogawa, Yui; Tsuji, Masaharu; Mizuno, Seigi; Hibino, Hiroki

    2012-08-16

    For electronic applications, synthesis of large-area, single-layer graphene with high crystallinity is required. One of the most promising and widely employed methods is chemical vapor deposition (CVD) using Cu foil/film as the catalyst. However, the CVD graphene is generally polycrystalline and contains a significant amount of domain boundaries that limit intrinsic physical properties of graphene. In this Perspective, we discuss the growth mechanism of graphene on a Cu catalyst and review recent development in the observation and control of the domain structure of graphene. We emphasize the importance of the growth condition and crystallinity of the Cu catalyst for the realization of large-area, single-crystalline graphene. PMID:26295775

  3. Hybrid Ytterbium-doped large-mode-area photonic crystal fiber amplifier for long wavelengths.

    PubMed

    Petersen, Sidsel R; Alkeskjold, Thomas T; Poli, Federica; Coscelli, Enrico; Jørgensen, Mette M; Laurila, Marko; Lægsgaard, Jesper; Broeng, Jes

    2012-03-12

    A large-mode-area Ytterbium-doped photonic crystal fiber amplifier with build-in gain shaping is presented. The fiber cladding consists of a hexagonal lattice of air holes, where three rows are replaced with circular high-index inclusions. Seven missing air holes define the large-mode-area core. Light confinement is achieved by combined index and bandgap guiding, which allows for single-mode operation and gain shaping through distributed spectral filtering of amplified spontaneous emission. The fiber properties are ideal for amplification in the long wavelength regime of the Ytterbium gain spectrum above 1100 nm, and red shifting of the maximum gain to 1130 nm is demonstrated. PMID:22418478

  4. Large area mapping of soil moisture using the ESTAR passive microwave radiometer

    NASA Technical Reports Server (NTRS)

    Jackson, T. J.; Levine, D. M.; Swift, C. T.; Schmugge, T. J.

    1994-01-01

    Investigations designed to study land surface hydrologic-atmospheric interactions, showing the potential of L band passive microwave radiometry for measuring surface soil moisture over large areas, are discussed. Satisfying the data needs of these investigations requires the ability to map large areas rapidly. With aircraft systems this means a need for more beam positions over a wider swath on each flightline. For satellite systems the essential problem is resolution. Both of these needs are currently being addressed through the development and verification of Electronically Scanned Thinned Array Radiometer (ESTAR) technology. The ESTAR L band radiometer was evaluated for soil moisture mapping applications in two studies. The first was conducted over the semiarid rangeland Walnut Gulch watershed located in south eastern Arizona (U.S.). The second was performed in the subhumid Little Washita watershed in south west Oklahoma (U.S.). Both tests showed that the ESTAR is capable of providing soil moisture with the same level of accuracy as existing systems.

  5. Photon counting pixel and array in amorphous silicon technology for large area digital medical imaging applications

    NASA Astrophysics Data System (ADS)

    Yazdandoost, Mohammad Y.; Shin, Kyung W.; Safavian, Nader; Taghibakhsh, Farhad; Karim, Karim S.

    2010-04-01

    A single photon counting Voltage Controlled Oscillator (VCO) based pixel architecture in amorphous silicon (a-Si) technology is reported for large area digital medical imaging. The VCO converts X-ray generated input charge into an output oscillating frequency signal. Experimental results for an in-house fabricated VCO circuit in a-Si technology are presented and external readout circuits to extract the image information from the VCO's frequency output are discussed. These readout circuits can be optimized to reduce the fixed pattern noise and fringing effects in an imaging array containing many such VCO pixels. Noise estimations, stability simulations and measurements for the fabricated VCO are presented. The reported architecture is particularly promising for large area photon counting applications (e.g. low dose fluoroscopy, dental computed tomography (CT)) due to its very low input referred electronic noise, high sensitivity and ease of fabrication in low cost a-Si technology.

  6. The Area Law in Matrix Models for Large N QCD Strings

    NASA Astrophysics Data System (ADS)

    Anagnostopoulos, K. N.; Bietenholz, W.; Nishimura, J.

    We study the question whether matrix models obtained in the zero volume limit of 4d Yang-Mills theories can describe large N QCD strings. The matrix model we use is a variant of the Eguchi-Kawai model in terms of Hermitian matrices, but without any twists or quenching. This model was originally proposed as a toy model of the IIB matrix model. In contrast to common expectations, we do observe the area law for Wilson loops in a significant range of scale of the loop area. Numerical simulations show that this range is stable as N increases up to 768, which strongly suggests that it persists in the large N limit. Hence the equivalence to QCD strings may hold for length scales inside a finite regime.

  7. Fabrication of large area silicon solar cells by rapid thermal processing

    NASA Astrophysics Data System (ADS)

    Sivoththaman, S.; Laureys, W.; Nijs, J.; Mertens, R.

    1995-10-01

    Large area n+pp+ solar cells have been fabricated on 10 cm×10 cm pseudo-quasi-square CZ silicon wafers (1 Ω cm, p-type) predominantly used by the photovoltaic (PV) industry. All the high-temperature steps have been performed by rapid thermal processing (RTP). Emitter formation, back surface field (BSF) formation, and surface oxidation have been performed in just two RTP steps each lasting 50 s. Solar cells of 15% efficiency have been fabricated this way, demonstrating the applicability of this low thermal budget technology to large area, modulable size, industrial quality Si wafers. Furthermore, the rapid thermal oxidation (RTO) is shown to result in good quality thin oxides with Si/SiO2 interface trap densities (Dit)<1011 cm-3 eV-1 near-midgap.

  8. Large-area CdTe diode detector for space application

    NASA Astrophysics Data System (ADS)

    Nakazawa, K.; Takahashi, T.; Watanabe, S.; Sato, G.; Kouda, M.; Okada, Y.; Mitani, T.; Kobayashi, Y.; Kuroda, Y.; Onishi, M.; Ohno, R.; Kitajima, H.

    2003-10-01

    The current status of Schottky CdTe diode detectors, especially in view of their space application for hard X-ray and gamma-ray astronomy, are reported. For practical use in space science, a large-area CdTe diode with a size of 21.5×21.5mm2 and a thickness of 0.5mm was developed. A good energy resolution, 2.8keV (FWHM) at -20°C, and high homogeneity to within 0.2% over the detector were achieved for the spectral performance. This device has successfully passed a series of tests required for its use in space, in view of utilizing Japanese M-V rockets. The tests include the mechanical environment test, vacuum test, long run for weeks and proton-beam radiation. Initial results from a 2×2 segmented electrode large-area device with a guard-ring are also presented.

  9. Fabrication of large-area and low mass critical-angle x-ray transmission gratings

    NASA Astrophysics Data System (ADS)

    Heilmann, Ralf K.; Bruccoleri, Alex R.; Guan, Dong; Schattenburg, Mark L.

    2014-07-01

    Soft x-ray spectroscopy of celestial sources with high resolving power R = E/ΔE and large collecting area addresses important science listed in the Astro2010 Decadal Survey New Worlds New Horizons, such as the growth of the large scale structure of the universe and its interaction with active galactic nuclei, the kinematics of galactic outflows, as well as coronal emission from stars and other topics. Numerous studies have shown that a transmission grating spectrometer based on lightweight critical-angle transmission (CAT) gratings can deliver R = 3000-5000 and large collecting area with high efficiency and minimal resource requirements, providing spectroscopic figures of merit at least an order of magnitude better than grating spectrometers on Chandra and XMM-Newton, as well as future calorimeter-based missions. The recently developed CAT gratings combine the advantages of transmission gratings (low mass, relaxed figure and alignment tolerances) and blazed reflection gratings (high broad band diffraction efficiency, utilization of higher diffraction orders). Their working principle based on blazing through reflection off the smooth, ultra-high aspect ratio grating bar sidewalls has previously been demonstrated on small samples with x rays. For larger gratings (area greater than 1 inch square) we developed a fabrication process for grating membranes with a hierarchy of integrated low-obscuration supports. The fabrication involves a combination of advanced lithography and highly anisotropic dry and wet etching techniques. We report on the latest fabrication results of free-standing, large-area CAT gratings with polished sidewalls and preliminary x-ray tests.

  10. Caustic Recycle from Hanford Tank Waste Using Large Area NaSICON Structures (LANS)

    SciTech Connect

    Fountain, Matthew S.; Sevigny, Gary J.; Balagopal, S.; Bhavaraju, S.

    2009-03-31

    This report presents the results of a 5-day test of an electrochemical bench-scale apparatus using a proprietary (NAS-GY) material formulation of a (Na) Super Ion Conductor (NaSICON) membrane in a Large Area NaSICON Structures (LANS) configuration. The primary objectives of this work were to assess system performance, membrane seal integrity, and material degradation while removing Na from Group 5 and 6 tank waste from the Hanford Site.

  11. Lithography-free large-area metamaterials for stable thermophotovoltaic energy conversion

    DOE PAGESBeta

    Coppens, Zachary J.; Kravchenko, Ivan I.; Valentine, Jason G.

    2016-02-08

    A large-area metamaterial thermal emitter is fabricated using facile, lithography-free techniques. The device is composed of conductive oxides, refractory ceramics, and noble metals and shows stable, selective emission after exposure to 1173 K for 22 h in oxidizing and inert atmospheres. Lastly, the results indicate that the metamaterial can be used to achieve high-performance thermophotovoltaic devices for applications such as portable power generation.

  12. Polarization switch of four-wave mixing in large mode area hybrid photonic crystal fibers.

    PubMed

    Petersen, Sidsel R; Alkeskjold, Thomas T; Olausson, Christina B; Lægsgaard, Jesper

    2015-02-15

    Degenerate spontaneous four-wave mixing is considered in a large mode area hybrid photonic crystal fiber. Numerical and experimental results show birefringence assisted four-wave mixing for a certain polarization state of the pump field. The parametric gain can be turned on and off by switching the polarization state of the pump field between the two principal axis of the hybrid photonic crystal fiber. PMID:25680131

  13. Implications of Harvest on the Boundaries of Protected Areas for Large Carnivore Viewing Opportunities.

    PubMed

    Borg, Bridget L; Arthur, Stephen M; Bromen, Nicholas A; Cassidy, Kira A; McIntyre, Rick; Smith, Douglas W; Prugh, Laura R

    2016-01-01

    The desire to see free ranging large carnivores in their natural habitat is a driver of tourism in protected areas around the globe. However, large carnivores are wide-ranging and subject to human-caused mortality outside protected area boundaries. The impact of harvest (trapping or hunting) on wildlife viewing opportunities has been the subject of intense debate and speculation, but quantitative analyses have been lacking. We examined the effect of legal harvest of wolves (Canis lupus) along the boundaries of two North American National Parks, Denali (DNPP) and Yellowstone (YNP), on wolf viewing opportunities within the parks during peak tourist season. We used data on wolf sightings, pack sizes, den site locations, and harvest adjacent to DNPP from 1997-2013 and YNP from 2008-2013 to evaluate the relationship between harvest and wolf viewing opportunities. Although sightings were largely driven by wolf population size and proximity of den sites to roads, sightings in both parks were significantly reduced by harvest. Sightings in YNP increased by 45% following years with no harvest of a wolf from a pack, and sightings in DNPP were more than twice as likely during a period with a harvest buffer zone than in years without the buffer. These findings show that harvest of wolves adjacent to protected areas can reduce sightings within those areas despite minimal impacts on the size of protected wolf populations. Consumptive use of carnivores adjacent to protected areas may therefore reduce their potential for non-consumptive use, and these tradeoffs should be considered when developing regional wildlife management policies. PMID:27124729

  14. Implications of Harvest on the Boundaries of Protected Areas for Large Carnivore Viewing Opportunities

    PubMed Central

    Borg, Bridget L.; Arthur, Stephen M.; Bromen, Nicholas A.; Cassidy, Kira A.; McIntyre, Rick; Smith, Douglas W.; Prugh, Laura R.

    2016-01-01

    The desire to see free ranging large carnivores in their natural habitat is a driver of tourism in protected areas around the globe. However, large carnivores are wide-ranging and subject to human-caused mortality outside protected area boundaries. The impact of harvest (trapping or hunting) on wildlife viewing opportunities has been the subject of intense debate and speculation, but quantitative analyses have been lacking. We examined the effect of legal harvest of wolves (Canis lupus) along the boundaries of two North American National Parks, Denali (DNPP) and Yellowstone (YNP), on wolf viewing opportunities within the parks during peak tourist season. We used data on wolf sightings, pack sizes, den site locations, and harvest adjacent to DNPP from 1997–2013 and YNP from 2008–2013 to evaluate the relationship between harvest and wolf viewing opportunities. Although sightings were largely driven by wolf population size and proximity of den sites to roads, sightings in both parks were significantly reduced by harvest. Sightings in YNP increased by 45% following years with no harvest of a wolf from a pack, and sightings in DNPP were more than twice as likely during a period with a harvest buffer zone than in years without the buffer. These findings show that harvest of wolves adjacent to protected areas can reduce sightings within those areas despite minimal impacts on the size of protected wolf populations. Consumptive use of carnivores adjacent to protected areas may therefore reduce their potential for non-consumptive use, and these tradeoffs should be considered when developing regional wildlife management policies. PMID:27124729

  15. [Effects of large-area planting water hyacinth on macro-benthos community structure and biomass].

    PubMed

    Liu, Guo-Feng; Liu, Hai-Qin; Zhang, Zhi-Yong; Zhang, Ying-Ying; Yan, Shao-Hua; Zhong, Ji-Cheng; Fan, Cheng-Xin

    2010-12-01

    The effects on macro-benthos and benthos environment of planting 200 hm2 water hyacinth (E. crassipens) in Zhushan Bay, Lake Taihu, were studied during 8-10 months consecutive surveys. Results indicated that average densities of mollusca (the main species were Bellamya aeruginosa) in far-planting, near-planting and planting area were 276.67, 371.11 and 440.00 ind/m2, respectively, and biomass were 373.15, 486.57 and 672.54 g/m2, respectively, showed that average density and biomass of planting area's were higher than those of others. However, the average density and biomass of Oligochaeta (the main species was Limodrilus hoffmeisteri) and Chironomidae in planting area were lower than that of outside planting area. The density and biomass of three dominant species of benthic animal increased quickly during 8-9 months, decreased quickly in October inside and outside water hyacinth planting area. The reason of this phenomenon could be possible that lots of cyanobacteria cells died and consumed dissolve oxygen in proceed decomposing. Algae cells released lots of phosphorus and nitrogen simultaneously, so macro-benthos died in this environment. The indexes of Shannon-Weaver and Simpson indicated that water environment was in moderate polluted state. On the basis of the survey results, the large-area and high-density planting water hyacinth haven't demonstrated a great impact on macrobenthos and benthos environment in short planting time (about 6 months planting time). PMID:21360881

  16. Regional contraction of brain surface area involves three large-scale networks in schizophrenia.

    PubMed

    Palaniyappan, Lena; Mallikarjun, Pavan; Joseph, Verghese; White, Thomas P; Liddle, Peter F

    2011-07-01

    In schizophrenia, morphological changes in the cerebral cortex have been primarily investigated using volumetric or cortical thickness measurements. In healthy subjects, as the brain size increases, the surface area expands disproportionately when compared to the scaling of cortical thickness. In this structural MRI study, we investigated the changes in brain surface area in schizophrenia by constructing relative areal contraction/expansion maps showing group differences in surface area using Freesurfer software in 57 patients and 41 controls. We observed relative areal contraction affecting Default Mode Network, Central Executive Network and Salience Network, in addition to other regions in schizophrenia. We confirmed the surface area reduction across these three large-scale brain networks by undertaking further region-of-interest analysis of surface area. We also observed a significant hemispheric asymmetry in the surface area changes, with the left hemisphere showing a greater reduction in the areal contraction maps. Our findings suggest that a fundamental disturbance in cortical expansion is likely in individuals who develop schizophrenia. PMID:21497489

  17. Rapid fabrication of large-area, corrosion-resistant superhydrophobic Mg alloy surfaces.

    PubMed

    Xu, Wenji; Song, Jinlong; Sun, Jing; Lu, Yao; Yu, Ziyuan

    2011-11-01

    A superhydrophobic magnesium (Mg) alloy surface was successfully fabricated via a facile electrochemical machining process, and subsequently covered with a fluoroalkylsilane (FAS) film. The surface morphologies and chemical compositions were investigated using a scanning electron microscope (SEM) equipped with an energy-dispersive spectroscopy (EDS) and a Fourier-transform infrared spectrophotometer (FTIR). The results show hierarchal rough structures and an FAS film with a low surface energy on the Mg alloy surfaces, which confers good superhydrophobicity with a water contact angle of 165.2° and a water tilting angle of approximately 2°. The processing conditions, such as the processing time and removal rate per unit area at a constant removal mass per unit area, were investigated to determine their effects on the superhydrophobicity. Interestingly, when the removal mass per unit area is constant at approximately 11.10 mg/cm(2), the superhydrophobicity does not change with the removal rate per unit area. Therefore, a superhydrophobic Mg alloy surface can be rapidly fabricated based on this property. A large-area superhydrophobic Mg alloy surface was also fabricated for the first time using a small-area moving cathode. The corrosion resistance and durability of the superhydrophobic surfaces were also examined. PMID:22008385

  18. How diversification rates and diversity limits combine to create large-scale species–area relationships

    PubMed Central

    Kisel, Yael; McInnes, Lynsey; Toomey, Nicola H.; Orme, C. David L.

    2011-01-01

    Species–area relationships (SARs) have mostly been treated from an ecological perspective, focusing on immigration, local extinction and resource-based limits to species coexistence. However, a full understanding across large regions is impossible without also considering speciation and global extinction. Rates of both speciation and extinction are known to be strongly affected by area and thus should contribute to spatial patterns of diversity. Here, we explore how variation in diversification rates and ecologically mediated diversity limits among regions of different sizes can result in the formation of SARs. We explain how this area-related variation in diversification can be caused by either the direct effects of area or the effects of factors that are highly correlated with area, such as habitat diversity and population size. We also review environmental, clade-specific and historical factors that affect diversification and diversity limits but are not highly correlated with region area, and thus are likely to cause scatter in observed SARs. We present new analyses using data on the distributions, ages and traits of mammalian species to illustrate these mechanisms; in doing so we provide an integrated perspective on the evolutionary processes shaping SARs. PMID:21807732

  19. Combining nanoimprint lithography with dynamic templating for the fabrication of dense, large-area nanoparticle arrays

    NASA Astrophysics Data System (ADS)

    Golze, Spencer D.

    The study of nanomaterials is a developing science with potentially large benefits in the development of catalysts, optical and chemical sensors, and solid state memory devices. As several of these devices require large arrays of nanoparticles, one of the greatest obstacles in material characterization and device development is the reliable manufacture of nanopatterns over a large surface area. In addition, various applications require different nanoparticle size and density. High density arrays with small nanoparticle sizes are difficult to achieve over a large surface area using current manufacturing processes. Herein, Nanoimprint Lithography (NIL) and Dynamic Templating are combined to create a new manufacturing process capable of developing high density arrays with small nanoparticle sizes. The NIL process involves the stamping of a polymer coated substrate by a silicon stamp with patterned nanofeatures. The stamp is then removed, leaving the pattern in the polymer, which is first etched and then coated with a thin layer of metal, filling the recessed regions of the pattern. The excess polymer is dissolved, leaving a pattern of nanoparticles on the substrate matching the pattern on the stamp. When Dynamic Templating is applied, a very thin layer of metal can be coated, which forms small nanoparticle sizes when dewetted. A custom NIL system has been developed to combine these two processes together, which has now proven to yield consistent large-area, dense arrays with a small nanoparticle size. An array spacing of 700 nm has been achieved, along with a nanoparticle size of 90 nm. Arrays have been created in gold and palladium, where there is now the potential to combine them with other solution-based syntheses which should lead to complex nanoparticle geometries suitable for sensor applications.

  20. Detection of Steel Fatigue Cracks with Strain Sensing Sheets Based on Large Area Electronics

    PubMed Central

    Yao, Yao; Glisic, Branko

    2015-01-01

    Reliable early-stage damage detection requires continuous monitoring over large areas of structure, and with sensors of high spatial resolution. Technologies based on Large Area Electronics (LAE) can enable direct sensing and can be scaled to the level required for Structural Health Monitoring (SHM) of civil structures and infrastructure. Sensing sheets based on LAE contain dense arrangements of thin-film strain sensors, associated electronics and various control circuits deposited and integrated on a flexible polyimide substrate that can cover large areas of structures. This paper presents the development stage of a prototype strain sensing sheet based on LAE for crack detection and localization. Two types of sensing-sheet arrangements with size 6 × 6 inch (152 × 152 mm) were designed and manufactured, one with a very dense arrangement of sensors and the other with a less dense arrangement of sensors. The sensing sheets were bonded to steel plates, which had a notch on the boundary, so the fatigue cracks could be generated under cyclic loading. The sensors within the sensing sheet that were close to the notch tip successfully detected the initialization of fatigue crack and localized the damage on the plate. The sensors that were away from the crack successfully detected the propagation of fatigue cracks based on the time history of the measured strain. The results of the tests have validated the general principles of the proposed sensing sheets for crack detection and identified advantages and challenges of the two tested designs. PMID:25853407

  1. Testing of a Neon Loop Heat Pipe for Large Area Cryocooling

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Robinson, Franklin Lee

    2014-01-01

    Cryocooling of large areas such as optics, detector arrays, and cryogenic propellant tanks is required for future NASA missions. A cryogenic loop heat pipe (CLHP) can provide a closed-loop cooling system for this purpose and has many advantages over other devices in terms of reduced mass, reduced vibration, high reliability, and long life. A neon CLHP was tested extensively in a thermal vacuum chamber using a cryopump as the heat sink to characterize its transient and steady performance and verify its ability to cool large areas or components. Tests conducted included loop cool-down from the ambient temperature, startup, power cycle, heat removal capability, loop capillary limit and recovery from a dry-out, low power operation, and long duration steady state operation. The neon CLHP demonstrated robust operation. The loop could be cooled from the ambient temperature to subcritical temperatures very effectively, and could start successfully by applying power to both the pump and evaporator without any pre-conditioning. It could adapt to changes in the pump power andor evaporator power, and reach a new steady state very quickly. The evaporator could remove heat loads between 0.25W and 4W. When the pump capillary limit was exceeded, the loop could resume its normal function by reducing the pump power. Steady state operations were demonstrated for up to 6 hours. The ability of the neon loop to cool large areas was therefore successfully verified.

  2. Large area event counting detectors with high spatial and temporal resolution

    NASA Astrophysics Data System (ADS)

    Siegmund, O. H. W.; McPhate, J. B.; Vallerga, J. V.; Tremsin, A. S.; Frisch, H. E.; Elam, J. W.; Mane, A. U.; Wagner, R. G.

    2014-04-01

    Novel large area microchannel plates (MCPs) constructed using micro-capillary arrays functionalized by atomic layer deposition (ALD) have been successfully demonstrated in large format detectors (10 cm and 20 cm) with cross delay line and cross strip readouts. Borosilicate micro-capillary substrates allow robust MCPs to be made in sizes to 20 cm, the intrinsic background rates are low ( < 0.06 events cm-2 sec-1), the channel open area can be made as high as 85%, and the gain after preconditioning (vacuum bake and burn-in) shows virtually no change over > 7 C cm-2 extracted charge. We have constructed a number of detectors with these novel MCPs, including a 10 × 10 cm cross strip readout device and 20 × 20 cm delay line readout sensors. The cross strip detector has very high spatial resolution (the 20 μm MCP pores can be resolved, thus obtaining ~ 5k × 5k resolution elements), good time resolution ( < 1 ns), and high event rate ( > 5 million counts/s at 20% dead time), while operating at relatively low gain ( ~ 106). The 20 × 20 cm delay line detectors have achieved spatial resolutions of ~ 50 μm and event rates of several MHz, with good gain and background uniformity and < 200 ps event time tagging. Progress has also been made in construction of a 20 × 20 cm sealed tube optical imager, and we have achieved > 20% quantum efficiency and good uniformity for large area (20 cm) bialkali photocathodes.

  3. Rapid, High-Resolution Forest Structure and Terrain Mapping over Large Areas using Single Photon Lidar

    PubMed Central

    Swatantran, Anu; Tang, Hao; Barrett, Terence; DeCola, Phil; Dubayah, Ralph

    2016-01-01

    Single photon lidar (SPL) is an innovative technology for rapid forest structure and terrain characterization over large areas. Here, we evaluate data from an SPL instrument - the High Resolution Quantum Lidar System (HRQLS) that was used to map the entirety of Garrett County in Maryland, USA (1700 km2). We develop novel approaches to filter solar noise to enable the derivation of forest canopy structure and ground elevation from SPL point clouds. SPL attributes are compared with field measurements and an existing leaf-off, low-point density discrete return lidar dataset as a means of validation. We find that canopy and ground characteristics from SPL are similar to discrete return lidar despite differences in wavelength and acquisition periods but the higher point density of the SPL data provides more structural detail. Our experience suggests that automated noise removal may be challenging, particularly over high albedo surfaces and rigorous instrument calibration is required to reduce ground measurement biases to accepted mapping standards. Nonetheless, its efficiency of data collection, and its ability to produce fine-scale, three-dimensional structure over large areas quickly strongly suggests that SPL should be considered as an efficient and potentially cost-effective alternative to existing lidar systems for large area mapping. PMID:27329078

  4. Step-Controllable Electric-Field-Assisted Nanoimprint Lithography for Uneven Large-Area Substrates.

    PubMed

    Wang, Chunhui; Shao, Jinyou; Tian, Hongmiao; Li, Xiangming; Ding, Yucheng; Li, Ben Q

    2016-04-26

    Large-area nanostructures are widely used in various fields, but fabrication on large-area uneven substrates poses a significant challenge. This study demonstrates a step-controllable electric-field-assisted nanoimprint lithography (e-NIL) method that can achieve conformal contact with uneven substrates for high fidelity nanostructuring. Experiments are used to demonstrate the method where a substrate coated with liquid resist is brought into contact with a flexible template driven by the applied electric field. Theoretical analysis based on the elasticity theory and electro-hydrodynamic theory is carried out. Effective voltage range and the saturation voltage are also discussed. A step-controllable release of flexible template is proposed and demonstrated to ensure the continuous contact between the template and an uneven substrate. This prevents formation of air traps and allows large area conformal contact to be achieved. A combination of Vacuum-electric field assisted step-controllable e-NIL is implemented in the developed prototype. Finally, photonic crystal nanostructures are successfully fabricated on a 4 in., 158 μm bow gallium nitride light-emitting diode epitaxial wafer using the proposed method, which enhance the light extraction property. PMID:27015525

  5. Video-rate structured illumination microscopy for high-throughput imaging of large tissue areas

    PubMed Central

    Schlichenmeyer, Tyler C.; Wang, Mei; Elfer, Katherine N.; Brown, J. Quincy

    2014-01-01

    We report the development of a structured illumination microscopy instrument specifically designed for the requirements for high-area-throughput, optically-sectioned imaging of large, fluorescently-stained tissue specimens. The system achieves optical sectioning frame-rates of up to 33 Hz (and pixel sampling rates of up to 138.4 MHz), by combining a fast, ferroelectric spatial light modulator for pattern generation with the latest large-format, high frame-rate scientific CMOS camera technology. Using a 10X 0.45 NA objective and a 7 mm/sec scan stage, we demonstrate 4.4 cm2/min area-throughput rates in bright tissue-simulating phantoms, and 2 cm2/min area-throughput rates in thick, highly-absorbing, fluorescently-stained muscle tissue, with 1.3 μm lateral resolution. We demonstrate high-contrast, high-resolution imaging of a fluorescently-stained 30.4 cm2 bovine muscle specimen in 15 minutes comprising 7.55 gigapixels, demonstrating the feasibility of the approach for gigapixel imaging of large tissues in short timeframes, such as would be needed for intraoperative imaging of tumor resection specimens. PMID:24575333

  6. Rapid, High-Resolution Forest Structure and Terrain Mapping over Large Areas using Single Photon Lidar.

    PubMed

    Swatantran, Anu; Tang, Hao; Barrett, Terence; DeCola, Phil; Dubayah, Ralph

    2016-01-01

    Single photon lidar (SPL) is an innovative technology for rapid forest structure and terrain characterization over large areas. Here, we evaluate data from an SPL instrument - the High Resolution Quantum Lidar System (HRQLS) that was used to map the entirety of Garrett County in Maryland, USA (1700 km(2)). We develop novel approaches to filter solar noise to enable the derivation of forest canopy structure and ground elevation from SPL point clouds. SPL attributes are compared with field measurements and an existing leaf-off, low-point density discrete return lidar dataset as a means of validation. We find that canopy and ground characteristics from SPL are similar to discrete return lidar despite differences in wavelength and acquisition periods but the higher point density of the SPL data provides more structural detail. Our experience suggests that automated noise removal may be challenging, particularly over high albedo surfaces and rigorous instrument calibration is required to reduce ground measurement biases to accepted mapping standards. Nonetheless, its efficiency of data collection, and its ability to produce fine-scale, three-dimensional structure over large areas quickly strongly suggests that SPL should be considered as an efficient and potentially cost-effective alternative to existing lidar systems for large area mapping. PMID:27329078

  7. Laser microprocessing and nanoengineering of large-area functional micro/nanostructures

    NASA Astrophysics Data System (ADS)

    Tang, M.; Xie, X. Z.; Yang, J.; Chen, Z. C.; Xu, L.; Choo, Y. S.; Hong, M. H.

    2011-12-01

    Laser microprocessing and nanoengineering are of great interest to both scientists and engineers, since the inspired properties of functional micro/nanostructures over large areas can lead to numerous unique applications. Currently laser processing systems combined with high speed automation ensure the focused laser beam to process various materials at a high throughput and a high accuracy over large working areas. UV lasers are widely used in both laser microprocessing and nanoengineering. However by improving the processing methods, green pulsed laser is capable of replacing UV lasers to make high aspect ratio micro-grooves on fragile and transparent sapphire substrates. Laser micro-texturing can also tune the wetting property of metal surfaces from hydrophilic to super-hydrophobic at a contact angle of 161° without chemical coating. Laser microlens array (MLA) can split a laser beam into multiple laser beams and reduce the laser spot size down to sub-microns. It can be applied to fabricate split ring resonator (SRR) meta-materials for THz sensing, surface plasmonic resonance (SPR) structures for NIR and molding tools for soft lithography. Furthermore, laser interference lithography combined with thermal annealing can obtain a large area of sub-50nm nano-dot clusters used for SPR applications.

  8. Large-area pattern transfer of metallic nanostructures on glass substrates via interference lithography.

    PubMed

    Du, Ke; Wathuthanthri, Ishan; Mao, Weidong; Xu, Wei; Choi, Chang-Hwan

    2011-07-15

    In this paper, we report a simple and effective nanofabrication method for the pattern transfer of metallic nanostructures over a large surface area on a glass substrate. Photoresist (PR) nano-patterns, defined by laser interference lithography, are used as template structures where a metal film of controlled thickness is directly deposited and then transferred onto a glass substrate by the sacrificial etching of the PR inter-layer. The laser interference lithography, capable of creating periodic nano-patterns with good control of their dimensions and shapes over a relatively large area, allows the wafer-scale pattern transfer of metallic nanostructures in a very convenient way. By using the approach, we have successfully fabricated on a glass substrate uniform arrays of hole, grating, and pillar patterns of Ti, Al, and Au in varying pattern periodicities (200 nm-1 µm) over a surface area of up to several cm(2) with little mechanical crack and delamination. Such robust metallic nanostructures defined well on a transparent glass substrate with large pattern coverage will lead to advanced scientific and engineering applications such as microfluidics and nanophotonics. PMID:21642762

  9. Large-area pattern transfer of metallic nanostructures on glass substrates via interference lithography

    NASA Astrophysics Data System (ADS)

    Du, Ke; Wathuthanthri, Ishan; Mao, Weidong; Xu, Wei; Choi, Chang-Hwan

    2011-07-01

    In this paper, we report a simple and effective nanofabrication method for the pattern transfer of metallic nanostructures over a large surface area on a glass substrate. Photoresist (PR) nano-patterns, defined by laser interference lithography, are used as template structures where a metal film of controlled thickness is directly deposited and then transferred onto a glass substrate by the sacrificial etching of the PR inter-layer. The laser interference lithography, capable of creating periodic nano-patterns with good control of their dimensions and shapes over a relatively large area, allows the wafer-scale pattern transfer of metallic nanostructures in a very convenient way. By using the approach, we have successfully fabricated on a glass substrate uniform arrays of hole, grating, and pillar patterns of Ti, Al, and Au in varying pattern periodicities (200 nm-1 µm) over a surface area of up to several cm2 with little mechanical crack and delamination. Such robust metallic nanostructures defined well on a transparent glass substrate with large pattern coverage will lead to advanced scientific and engineering applications such as microfluidics and nanophotonics.

  10. Development of lightweight blazed transmission gratings and large-area soft x-ray spectrographs

    NASA Astrophysics Data System (ADS)

    Heilmann, Ralf K.; Bruccoleri, Alex R.; Guan, Dong; Schattenburg, Mark L.

    2013-09-01

    Large area, high resolving power spectroscopy in the soft x-ray band can only be achieved with a state-of-the-art diffraction grating spectrometer, comprised of large collecting-area focusing optics with a narrow point spread function, large-area high-resolving power diffraction gratings, and small pixel, order sorting x-ray detectors. Recently developed critical-angle transmission (CAT) gratings combine the advantages of transmission gratings (low mass, relaxed figure and alignment tolerances) and blazed reflection gratings (high broad band diffraction efficiency, utilization of higher diffraction orders). Several new mission concepts containing CAT grating based spectrometers (AEGIS, AXSIO, SMART-X) promise to deliver unprecedented order-of-magnitude improvements in soft x-ray spectroscopy figures of merit related to the detection and characterization of emission and absorption lines, thereby addressing high-priority questions identified in the Astro2010 Decadal Survey "New Worlds New Horizons". We review the current status of CAT grating fabrication, present recent fabrication results, and describe our plans and technology development roadmap for the coming year and beyond.

  11. Performance of a Fieldable Large-Area, Coded-Aperture, Gamma Imager

    SciTech Connect

    Habte Ghebretatios, Frezghi; Cunningham, Mark F; Fabris, Lorenzo; Ziock, Klaus-Peter

    2007-01-01

    We recently developed a fieldable large-area, coded-aperture, gamma imager (the Large Area Imager - LAI). The instrument was developed to detect weak radiation sources in a fluctuating natural background. Ideally, the efficacy of the instrument is determined using receiver-operator statistics generated from measurement data in terms of probability of detection versus probability of false alarm. However, due to the impracticality of hiding many sources in public areas, it is difficult to measure the data required to generate receiver-operator characteristic (ROC) curves. Instead, we develop a high statistics "model source" from measurements of a real point source and then inject the model source into data collected from the world at large where, presumably, no source exists. In this paper we have applied this "source injection" technique to evaluate the performance of the LAI. We plotted ROC curves obtained for different source locations from the imager and for different source strengths when the source is injected at 50 m from the imager. The result shows that this prototype instrument provides excellent performance for a 1-mCi source at a distance of 50 m from the imager in a single pass at 25 mph.

  12. Rapid, High-Resolution Forest Structure and Terrain Mapping over Large Areas using Single Photon Lidar

    NASA Astrophysics Data System (ADS)

    Swatantran, Anu; Tang, Hao; Barrett, Terence; Decola, Phil; Dubayah, Ralph

    2016-06-01

    Single photon lidar (SPL) is an innovative technology for rapid forest structure and terrain characterization over large areas. Here, we evaluate data from an SPL instrument - the High Resolution Quantum Lidar System (HRQLS) that was used to map the entirety of Garrett County in Maryland, USA (1700 km2). We develop novel approaches to filter solar noise to enable the derivation of forest canopy structure and ground elevation from SPL point clouds. SPL attributes are compared with field measurements and an existing leaf-off, low-point density discrete return lidar dataset as a means of validation. We find that canopy and ground characteristics from SPL are similar to discrete return lidar despite differences in wavelength and acquisition periods but the higher point density of the SPL data provides more structural detail. Our experience suggests that automated noise removal may be challenging, particularly over high albedo surfaces and rigorous instrument calibration is required to reduce ground measurement biases to accepted mapping standards. Nonetheless, its efficiency of data collection, and its ability to produce fine-scale, three-dimensional structure over large areas quickly strongly suggests that SPL should be considered as an efficient and potentially cost-effective alternative to existing lidar systems for large area mapping.

  13. Toward Large-Area Sub-Arcsecond X-Ray Telescopes

    NASA Technical Reports Server (NTRS)

    ODell, Stephen L.; Aldcroft, Thomas L.; Allured, Ryan; Atkins, Carolyn; Burrows, David N.; Cao, Jian; Chalifoux, Brandon D.; Chan, Kai-Wing; Cotroneo, Vincenzo; Elsner, Ronald F.; Graham, Michael E.; Gubarev, Mikhail V.; Heilmann, Ralf K.; Johnson-Wilke, Raegan L.; Kilaru, Kiranmayee; Kolodziejczak, Jeffery J.; Lillie, Charles F.; McMuldroch, Stuart; Ramsey, Brian D.; Reid, Paul B.; Riveros, Raul E.; Roche, Jacqueline M.; Saha, Timo T.; Weisskopf, Martin C.; Zhang, William W.

    2014-01-01

    The future of x-ray astronomy depends upon development of x-ray telescopes with larger aperture areas (approx. = 3 square meters) and fine angular resolution (approx. = 1 inch). Combined with the special requirements of nested grazing-incidence optics, the mass and envelope constraints of space-borne telescopes render such advances technologically and programmatically challenging. Achieving this goal will require precision fabrication, alignment, mounting, and assembly of large areas (approx. = 600 square meters) of lightweight (approx. = 1 kilogram/square meter areal density) high-quality mirrors at an acceptable cost (approx. = 1 million dollars/square meter of mirror surface area). This paper reviews relevant technological and programmatic issues, as well as possible approaches for addressing these issues-including active (in-space adjustable) alignment and figure correction.

  14. Characterization of large area molybdenum disulphide by low energy electron microscopy

    NASA Astrophysics Data System (ADS)

    Man, K. L.; Yamaguchi, H.; Najmaei, S.; Lei, S.; Ajayan, P. M.; Lou, J.; Gupta, G.; Mohite, A. D.; Dani, K. M.

    2014-03-01

    Molybdenum disulphide (MoS2) is a new 2D direct-bandgap semiconductor material which has recently attracted substantial interest due to its potential applications in electronics, optics and energy storage. One of the challenges that needed to be overcome is in the large scale synthesis of high quality single crystal MoS2. Recently, it is shown that chemical vapor deposition (CVD) is a promising way of in the production of single layer MoS2. Here we report our study using low energy electron microscopy (LEEM) of large area MoS2 synthesized by CVD technique. The MoS2 samples are grown on Si/SiO2 substrates and then transferred onto n-doped Si substrates. In the LEEM images, we observe large triangular shaped MoS2 flakes along with irregular shaped flakes. Using low energy electron diffraction (LEED) and dark field imaging technique, we identify the triangularly shaped flakes as MoS2 single crystal while the irregular ones contain multiple domains orientations. These studies provide insight into the growth of large area single domain MoS2 crystals using CVD technique and the transfer process onto different substrates for potential device applications.

  15. Considerations about Large Area___Low Cost Fast Imaging Photo-detectors

    SciTech Connect

    Anderson, John; Attenkofer, Klaus; Delagnes, Eric; Frisch, Henry; Genat, Jean-Francois; Grabas, Herve; Heintz, Mary K.; May, Edward; Meehan, Samuel; Oberla, Eric; Ruckman, Larry L.; Tang, Fukun; Varner, Gary; Vavra, Jaroslav; Wetstein, Matthew; /Argonne

    2012-05-07

    The Large Area Picosecond Photodetectors described in this contribution incorporate a photocathode and a borosilicate glass capillary Micro-Channel Plate (MCP) pair functionalised by atomic layer deposition (ALD) of separate resistive and secondary emission materials. Initial testing with matched pairs of small glass capillary test disks has demonstrated gains of the order of 10{sup 5}-10{sup 6}. Compared to other fast imaging devices, these photodetectors are expected to provide timing resolutions in the 10-100 ps range, and two-dimension position in the sub-millimeter range. If daisy chained, large detectors read at both ends with fast digitising integrated electronics providing zero-suppressed calibrated data should be produced at relatively low cost in large quantities.

  16. Dark Forward Electrical Test Techniques Developed for Large-Area Photovoltaic Arrays

    NASA Technical Reports Server (NTRS)

    Kerslake, Thomas W.; Scheiman, David A.; Hoffman, David J.

    1998-01-01

    Spacecraft photovoltaic arrays (PVA's) must be carefully handled during ground integration processing and transportation to the launch site. Care is exercised to avoid damage that could degrade on-orbit electrical performance. Because of this damage risk, however, PVA's are typically deployed and illuminated with a light source so performance characteristics can be measured prior to launch. For large-area arrays, such as the Mir Cooperative Solar Array (2.7- by 18-m) and the International Space Station PVA blankets (4.6- by 31.7-m), this integrity check becomes resource intensive. Large test support structures are needed to offload the array during deployment in 1g, and large-aperture illumination equipment is required to uniformly illuminate array panels. Significant program time, funds, and manpower must be allocated for this kind of test program. Alternatively, launch site electrical performance tests can be bypassed with an attendant increase in risk.

  17. The Capabilities of the GLAST Large Area Telescope for Blazar Variability Studies

    NASA Technical Reports Server (NTRS)

    McEnery, Julie

    2006-01-01

    One of the more notable features of the Large Area Telescope (LAT) on GLAST is its extremely large field of view, which covers more than 20% of the sky at any instant. In survey mode the LAT will be rocked about the orbital plane to provide coverage of the entire gamma-ray sky above 20 MeV every three hours. This will be the default observing mode for the first year of operations and is likely to be the dominant observing mode throughout the rest of the mission. Thus the LAT will provide long, evenly sampled, gamma-ray lightcurves for a large number of sources. In this talk we describe the nature and quality of the data that will be provided by the LAT and use simulated lightcurves to illustrate some of the scientific questions that can be addressed with LAT observations.

  18. Large area double scattering telescope for balloon-borne studies of neutrons and gamma rays

    NASA Technical Reports Server (NTRS)

    Zych, A. D.; Herzo, D.; Koga, R.; Millard, W. A.; Moon, S.; Ryan, J.; Wilson, R.; White, R. S.; Dayton, B.

    1975-01-01

    A large area double scattering telescope for balloon-borne research is described. It measures the flux, energy and direction of 2-100 MeV neutrons and 0.5-30 MeV gamma rays. These measurements are made using time-of-flight and pulse height analysis techniques with two large tanks of mineral oil liquid scintillator. Results from Monte Carlo calculations of the efficiency, energy resolution and angular resolution are presented and the electronics implementation for the processing of 80 photomultiplier tubes signals will be discussed. The detector weighs 800 kg with a large part of this weight being the liquid scintillator (320 kg). It will be flown at 3 mbars for flight durations up to 40 hours. The first flight is planned for Spring, 1975.

  19. 20 CFR 645.525 - What special consideration will be given to rural areas and cities with large concentrations of...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... rural areas and cities with large concentrations of poverty? 645.525 Section 645.525 Employees' Benefits... cities with large concentrations of poverty? (a) Competitive grant awards will be targeted to geographic... rural areas and cities with large concentrations of residents living in poverty. (b) Grant...

  20. 20 CFR 645.525 - What special consideration will be given to rural areas and cities with large concentrations of...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... rural areas and cities with large concentrations of poverty? 645.525 Section 645.525 Employees' Benefits... cities with large concentrations of poverty? (a) Competitive grant awards will be targeted to geographic... rural areas and cities with large concentrations of residents living in poverty. (b) Grant...

  1. 20 CFR 645.525 - What special consideration will be given to rural areas and cities with large concentrations of...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... rural areas and cities with large concentrations of poverty? 645.525 Section 645.525 Employees' Benefits... cities with large concentrations of poverty? (a) Competitive grant awards will be targeted to geographic... rural areas and cities with large concentrations of residents living in poverty. (b) Grant...

  2. 20 CFR 645.525 - What special consideration will be given to rural areas and cities with large concentrations of...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... rural areas and cities with large concentrations of poverty? 645.525 Section 645.525 Employees' Benefits... cities with large concentrations of poverty? (a) Competitive grant awards will be targeted to geographic... rural areas and cities with large concentrations of residents living in poverty. (b) Grant...

  3. 20 CFR 645.525 - What special consideration will be given to rural areas and cities with large concentrations of...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... rural areas and cities with large concentrations of poverty? 645.525 Section 645.525 Employees' Benefits... cities with large concentrations of poverty? (a) Competitive grant awards will be targeted to geographic... rural areas and cities with large concentrations of residents living in poverty. (b) Grant...

  4. The design and application of large area intensive lens array focal spots measurement system

    NASA Astrophysics Data System (ADS)

    Chen, Bingzhen; Yao, Shun; Yang, Guanghui; Dai, Mingchong; Wang, Zhiyong

    2014-12-01

    Concentrating Photovoltaic (CPV) modules are getting thinner and using smaller cells now days. Correspondingly, large area intensive lens arrays with smaller unit dimension and shorter focal length are wanted. However, the size and power center of lens array focal spots usually differ from the design value and are hard to measure, especially under large area situation. It is because the machining error and deformation of material of the lens array are hard to simulate in the optical design process. Thus the alignment error between solar cells and focal spots in the module assembly process will be hard to control. Under this kind of situation, the efficiency of CPV module with thinner body and smaller cells is much lower than expected. In this paper, a design of large area lens array focal spots automatic measurement system is presented, as well as its prototype application results. In this system, a four-channel parallel light path and its corresponding image capture and process modules are designed. These modules can simulate focal spots under sunlight and have the spots image captured and processed using charge coupled devices and certain gray level algorithm. Thus the important information of focal spots such as spot size and location will be exported. Motion control module based on grating scale signal and interval measurement method are also employed in this system in order to get test results with high speed and high precision on large area lens array no less than 1m×0.8m. The repeatability of the system prototype measurement is +/-10μm with a velocity of 90 spot/min. Compared to the original module assembled using coordinates from optical design, modules assembled using data exported from the prototype is 18% higher in output power, reaching a conversion efficiency of over 31%. This system and its design can be used in the focal spot measurement of planoconvex lens array and Fresnel lens array, as well as other kinds of large area lens array application

  5. Continued improvment of large area, in situ sputter deposition of superconducting YBCO thin films

    NASA Technical Reports Server (NTRS)

    Truman, J. K.; White, W. R.; Ballentine, P. H.; Mallory, D. S.; Kadin, A. M.

    1993-01-01

    The deposition of thin films of superconducting YBa2Cu3O7-x onto substrates of up to 3-in diameter by an integrated off-axis sputtering is reported. The substrate is located above the center of an 8-in-diameter YBCO planar target, and, in conjunction with a negative ion shield, negative ion effects are avoided. A large radiant heater provides backside, noncontact heating of the bare substrates. YBCO films have been grown on polished 1-cm2 MgO and LaAlO3 substrates with Tc = 90 K or greater, Jc = 2.5 x 10 exp 6 A/sq cm or greater at 77 K, and microwave surface resistance Rs less than 0.4 micro-ohm at 77 K and 10 GHz. The films have a very smooth surface morphology. Uniformity data for LaAlO3 substrates are less than +/-5 percent in Rs. Thickness uniformity results for 3-in substrates indicate less than 10 percent variation. The growth of epitaxial insulating films for use with YBCO films and application of the YBCO films in microwave devices are briefly discussed.

  6. A simulation study of Large Area Crop Inventory Experiment (LACIE) technology

    NASA Technical Reports Server (NTRS)

    Ziegler, L. (Principal Investigator); Potter, J.

    1979-01-01

    The author has identified the following significant results. The LACIE performance predictor (LPP) was used to replicate LACIE phase 2 for a 15 year period, using accuracy assessment results for phase 2 error components. Results indicated that the (LPP) simulated the LACIE phase 2 procedures reasonably well. For the 15 year simulation, only 7 of the 15 production estimates were within 10 percent of the true production. The simulations indicated that the acreage estimator, based on CAMS phase 2 procedures, has a negative bias. This bias was too large to support the 90/90 criterion with the CV observed and simulated for the phase 2 production estimator. Results of this simulation study validate the theory that the acreage variance estimator in LACIE was conservative.

  7. Sensing sheets based on large area electronics for fatigue crack detection

    NASA Astrophysics Data System (ADS)

    Yao, Yao; Glisic, Branko

    2015-03-01

    Reliable early-stage damage detection requires continuous structural health monitoring (SHM) over large areas of structure, and with high spatial resolution of sensors. This paper presents the development stage of prototype strain sensing sheets based on Large Area Electronics (LAE), in which thin-film strain gauges and control circuits are integrated on the flexible electronics and deposited on a polyimide sheet that can cover large areas. These sensing sheets were applied for fatigue crack detection on small-scale steel plates. Two types of sensing-sheet interconnects were designed and manufactured, and dense arrays of strain gauge sensors were assembled onto the interconnects. In total, four (two for each design type) strain sensing sheets were created and tested, which were sensitive to strain at virtually every point over the whole sensing sheet area. The sensing sheets were bonded to small-scale steel plates, which had a notch on the boundary so that fatigue cracks could be generated under cyclic loading. The fatigue tests were carried out at the Carleton Laboratory of Columbia University, and the steel plates were attached through a fixture to the loading machine that applied cyclic fatigue load. Fatigue cracks then occurred and propagated across the steel plates, leading to the failure of these test samples. The strain sensor that was close to the notch successfully detected the initialization of fatigue crack and localized the damage on the plate. The strain sensor that was away from the crack successfully detected the propagation of fatigue crack based on the time history of measured strain. Overall, the results of the fatigue tests validated general principles of the strain sensing sheets for crack detection.

  8. Ultraclean and large-area monolayer hexagonal boron nitride on Cu foil using chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Wen, Yao; Shang, Xunzhong; Dong, Ji; Xu, Kai; He, Jun; Jiang, Chao

    2015-07-01

    Atomically thin hexagonal boron nitride (h-BN) has been demonstrated to be an excellent dielectric layer as well as an ideal van der Waals epitaxial substrate for fabrication of two-dimensional (2D) atomic layers and their vertical heterostructures. Although many groups have obtained large-scale monolayer h-BN through low pressure chemical vapor deposition (LPCVD), it is still a challenge to grow clean monolayers without the reduction of domain size. Here we report the synthesis of large-area (4 × 2 cm2) high quality monolayer h-BN with an ultraclean and unbroken surface on copper foil by using LPCVD. A detailed investigation of the key factors affecting growth and transfer of the monolayer was carried out in order to eliminate the adverse effects of impurity particles. Furthermore, an optimized transfer approach allowed the nondestructive and clean transfer of the monolayer from copper foil onto an arbitrary substrate, including a flexible substrate, under mild conditions. Atomic force microscopy indicated that the root-mean-square (RMS) roughness of the monolayer h-BN on SiO2 was less than 0.269 nm for areas with fewer wrinkles. Selective area electron diffraction analysis of the h-BN revealed a pattern of hexagonal diffraction spots, which unambiguously demonstrated its highly crystalline character. Our work paves the way toward the use of ultraclean and large-area monolayer h-BN as the dielectric layer in the fabrication of high performance electronic and optoelectronic devices for novel 2D atomic layer materials.

  9. Modified and double-clad large mode-area leakage channel fibers for extreme temperature conditions

    NASA Astrophysics Data System (ADS)

    Thavasi Raja, G.; Varshney, Shailendra K.

    2015-03-01

    Recently large-mode-area hybrid leakage channel fibers (HLCFs) were reported to overcome the limitation on mode area with single-mode (SM) operation for the practical bending radius of 7.5 cm at the preferred wavelength of 1064 nm. In this paper, we present the effects of a thermally induced refractive index change on the mode area of bend-compensated extremely LMA modified HLCFs (M-HLCFs) and double-clad M-HLCFs. A full-vectorial finite-element method-based modal solver is used to obtain the modal characteristics of M-HLCFs in various heat load conditions. Numerical simulations reveal that the effective mode area of M-HLCFs is ˜1433 μm2 at room temperature, which marginally decreases to ˜1387 μm2 while SM operation is maintained when the temperature distribution rises to ˜125 °C over the fiber geometry during high-power operations. We have also investigated a double-clad M-HLCF design exhibiting a mode area > ˜ 1000 μm2 for all heat load density variations up to a maximum of 12 × 109 W m-3, corresponding to a 250 °C temperature in the center of the fiber core region.

  10. Using large area imaging to integrate biogeochemical data across spatial scales

    NASA Astrophysics Data System (ADS)

    Sapers, H. M.; Laquerre, A.; Phaneuf, M. W.; Osinski, G. R.

    2014-12-01

    Large Area Imaging (LAI) systems such as the Carl Zeiss "Atlas" module allow acquisition of SEM images on the scale of millimeters to centimeters with an image resolution ranging from nanometers to micrometers. This provides researchers with the powerful capability to investigate large areas of up to tens of millimeters in scale and expand anywhere within these areas to see details on the micrometer to nanometer scale while retaining full contextual information regarding the areas under investigation. Biogeochemical processes operate on multiple scales and evidence of these phenomena can be difficult to observe across scales. For example, microbial etching of glass occurs on a nanometer scale as organic acids locally lower pH and destabilize Si-O bonds. However, interpreting a pattern of glass etching as abiotic or biogenic depends on observations at the micrometer to centimeter scale to assess evidence for microbial populations and/or biological behavior, assess fluid flow, changes in elemental composition and mineralogy. LAI is particularly suited to the investigation of multi-scale, interdisciplinary biogeochemical datasets. Using LAI we have generated contiguous image data at resolutions as high as 100 nm (pixel size) for areas approaching 25 cm2, using backscattered and secondary electrons in both traditional high vacuum and variable pressure SEM modes. Image stitching produces seamless mosaics composed of multiple image tiles; mosaic acquisition times can be as little as a few hours of fully automated operation. Using this primary information, additional micrometer-scale data sets such as EDX spectroscopy, millimeter-scale datasets such as transmitted light photomicrographs, and nanometer-scale information such as synchrotron-based spectroscopy, can be registered and fused with the LAI SEM images. LAI and data fusion facilitates critical connections across spatial scales to test hypotheses that cross the threshold of traditional microscopy methods.

  11. Widefield TSCSPC-systems with large-area-detectors: application in simultaneous multi-channel-FLIM

    NASA Astrophysics Data System (ADS)

    Stepanov, Sergei; Bakhlanov, Sergei; Drobchenko, Evgeny; Eckert, Hann-Jörg; Kemnitz, Klaus

    2010-11-01

    Novel proximity-type Time- and Space-Correlated Single Photon Counting (TSCSPC) crossed-delay-line (DL)- and multi-anode (MA)-systems of outstanding performance and homogeneity were developed, using large-area detector heads of 25 and 40 mm diameter. Instrument response functions IRF(space) = (60 +/- 5) μm FWHM and IRF(time) = (28 +/- 3) ps FWHM were achieved over the full 12 cm2 area of the detector. Deadtime at throughput of 105 cps is 10% for "high-resolution" system and 5% in the "video"-system at 106 cps, at slightly reduced time- and space resolution. A fluorescence lifetime of (3.5 +/- 1) ps can be recovered from multi-exponential dynamics of a single living cyanobacterium (Acaryochloris marina). The present large-area detectors are particularly useful in simultaneous multichannel applications, such as 2-colour anisotropy or 4-colour lifetime imaging, utilizing dual- or quad-view image splitters. The long-term stability, low- excitation-intensity (< 100 mW/cm2) widefield systems enable minimal-invasive observation, without significant bleaching or photodynamic reactions, thus allowing long-period observation of up to several hours in living cells.

  12. Wearable light management system for light stimulated healing of large area chronic wounds (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Kallweit, David; Mayer, Jan; Fricke, Sören; Schnieper, Marc; Ferrini, Rolando

    2016-03-01

    Chronic wounds represent a significant burden to patients, health care professionals, and health care systems, affecting over 40 million patients and creating costs of approximately 40 billion € annually. We will present a medical device for photo-stimulated wound care based on a wearable large area flexible and disposable light management system consisting of a waveguide with incorporated micro- and nanometer scale optical structures for efficient light in-coupling, waveguiding and homogeneous illumination of large area wounds. The working principle of this innovative device is based on the therapeutic effects of visible light to facilitate the self-healing process of chronic wounds. On the one hand, light exposure in the red (656nm) induces growth of keratinocytes and fibroblasts in deeper layers of the skin. On the other hand, blue light (453nm) is known to have antibacterial effects predominately at the surface layers of the skin. In order to be compliant with medical requirements the system will consist of two elements: a disposable wound dressing with embedded flexible optical waveguides for the light management and illumination of the wound area, and a non-disposable compact module containing the light sources, a controller, a rechargeable battery, and a data transmission unit. In particular, we will report on the developed light management system. Finally, as a proof-of-concept, a demonstrator will be presented and its performances will be reported to demonstrate the potential of this innovative device.

  13. Large area and deep sub-wavelength interference lithography employing odd surface plasmon modes

    PubMed Central

    Liu, Liqin; Luo, Yunfei; Zhao, Zeyu; Zhang, Wei; Gao, Guohan; Zeng, Bo; Wang, Changtao; Luo, Xiangang

    2016-01-01

    In this paper, large area and deep sub-wavelength interference patterns are realized experimentally by using odd surface plasmon modes in the metal/insulator/metal structure. Theoretical investigation shows that the odd modes possesses much higher transversal wave vector and great inhibition of tangential electric field components, facilitating surface plasmon interference fringes with high resolution and contrast in the measure of electric field intensity. Interference resist patterns with 45 nm (∼λ/8) half-pitch, 50 nm depth, and area size up to 20 mm × 20 mm were obtained by using 20 nm Al/50 nm photo resist/50 nm Al films with greatly reduced surface roughness and 180 nm pitch exciting grating fabricated with conventional laser interference lithography. Much deeper resolution down to 19.5 nm is also feasible by decreasing the thickness of PR. Considering that no requirement of expensive EBL or FIB tools are employed, it provides a cost-effective way for large area and nano-scale fabrication. PMID:27466010

  14. Large-area CdTe/Al(sub)2O(sub)3 epitaxial films

    NASA Astrophysics Data System (ADS)

    Senokosev, E. A.; Sushkevich, K. D.; Usatyy, A. N.; Federov, V. M.

    1986-08-01

    In the group of A II B IV wide band gap semiconductor compounds, cadmium telluride is one of the most promising materials for converting solar energy into electricity. The wide practical use of CdTe for photoconverters has been restricted primarily by difficulties in growing high quality crystals with a large working surface area. The efficiency factor of polycrystalline film photocells does not exceed 5%. The search for and development of an effective technology for growing monocrystalline layers of CdTe having a large area with specified physical properties is one of the important directions in improving the operational characteristics of photocells. The production, study of the structure and emissive properties of epitaxial n-CdTe/Al2O3 films with an area of approximately equal 20 sq cm is discussed. Films with a thickness of 10 to 50 microns, which were grown in a quasiclosed container under conditions close to thermal equilibrium, were investigated. n-CdTe crystals with a specific resistance of 100,000 to 1,000,000 ohms x cm were used for deposition. A correlation between the type and resistance of the films and the parent material was discovered.

  15. Large-scale climatic patterns and area affected by mountain pine beetle in British Columbia, Canada

    NASA Astrophysics Data System (ADS)

    Macias Fauria, Marc; Johnson, E. A.

    2009-03-01

    We present evidence of high spatial synchrony in an area affected by mountain pine beetle (MPB, Dendroctonus ponderosae) across large distances in British Columbia, Canada, in a study of a spatially explicit database of an area affected by MPB-caused tree mortality for the period 1959-2002. We further show that large-scale climatic patterns (Pacific Decadal Oscillation (PDO) and, to a lesser degree, Arctic Oscillation (AO)) are strongly related to the observed MPB synchrony, and that they probably operate through controlling the frequency of extreme cold winter temperatures that affect MPB larvae survival. A smaller portion of the data's variability is linked to the onset of the two largest outbreaks in the studied period and might be attributed to dispersal from outbreak-prone areas or else to differences in microhabitat (e.g., host availability) in these regions. The onset of a warm PDO phase in 1976 favored MPB outbreaks by reducing the occurrence of extremely low winter temperatures province-wide. Likewise, the exceptionally high and persistent AO values of the late 1980s and 1990s enhanced MPB activity in the southern and northern parts of the region. Summer warmth cannot be discarded as an important agent at smaller scales.

  16. Large area and deep sub-wavelength interference lithography employing odd surface plasmon modes.

    PubMed

    Liu, Liqin; Luo, Yunfei; Zhao, Zeyu; Zhang, Wei; Gao, Guohan; Zeng, Bo; Wang, Changtao; Luo, Xiangang

    2016-01-01

    In this paper, large area and deep sub-wavelength interference patterns are realized experimentally by using odd surface plasmon modes in the metal/insulator/metal structure. Theoretical investigation shows that the odd modes possesses much higher transversal wave vector and great inhibition of tangential electric field components, facilitating surface plasmon interference fringes with high resolution and contrast in the measure of electric field intensity. Interference resist patterns with 45 nm (∼λ/8) half-pitch, 50 nm depth, and area size up to 20 mm × 20 mm were obtained by using 20 nm Al/50 nm photo resist/50 nm Al films with greatly reduced surface roughness and 180 nm pitch exciting grating fabricated with conventional laser interference lithography. Much deeper resolution down to 19.5 nm is also feasible by decreasing the thickness of PR. Considering that no requirement of expensive EBL or FIB tools are employed, it provides a cost-effective way for large area and nano-scale fabrication. PMID:27466010

  17. Microwave purification of large-area horizontally aligned arrays of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Xie, Xu; Jin, Sung Hun; Wahab, Muhammad A.; Islam, Ahmad E.; Zhang, Chenxi; Du, Frank; Seabron, Eric; Lu, Tianjian; Dunham, Simon N.; Cheong, Hou In; Tu, Yen-Chu; Guo, Zhilin; Chung, Ha Uk; Li, Yuhang; Liu, Yuhao; Lee, Jong-Ho; Song, Jizhou; Huang, Yonggang; Alam, Muhammad A.; Wilson, William L.; Rogers, John A.

    2014-11-01

    Recent progress in the field of single-walled carbon nanotubes (SWNTs) significantly enhances the potential for practical use of this remarkable class of material in advanced electronic and sensor devices. One of the most daunting challenges is in creating large-area, perfectly aligned arrays of purely semiconducting SWNTs (s-SWNTs). Here we introduce a simple, scalable, large-area scheme that achieves this goal through microwave irradiation of aligned SWNTs grown on quartz substrates. Microstrip dipole antennas of low work-function metals concentrate the microwaves and selectively couple them into only the metallic SWNTs (m-SWNTs). The result allows for complete removal of all m-SWNTs, as revealed through systematic experimental and computational studies of the process. As one demonstration of the effectiveness, implementing this method on large arrays consisting of ~20,000 SWNTs completely removes all of the m-SWNTs (~7,000) to yield a purity of s-SWNTs that corresponds, quantitatively, to at least to 99.9925% and likely significantly higher.

  18. Efficient transfer of large-area graphene films onto rigid substrates by hot pressing.

    PubMed

    Kang, Junmo; Hwang, Soonhwi; Kim, Jae Hwan; Kim, Min Hyeok; Ryu, Jaechul; Seo, Sang Jae; Hong, Byung Hee; Kim, Moon Ki; Choi, Jae-Boong

    2012-06-26

    Graphene films grown on metal substrates by chemical vapor deposition (CVD) method have to be safely transferred onto desired substrates for further applications. Recently, a roll-to-roll (R2R) method has been developed for large-area transfer, which is particularly efficient for flexible target substrates. However, in the case of rigid substrates such as glass or wafers, the roll-based method is found to induce considerable mechanical damages on graphene films during the transfer process, resulting in the degradation of electrical property. Here we introduce an improved dry transfer technique based on a hot-pressing method that can minimize damage on graphene by neutralizing mechanical stress. Thus, we enhanced the transfer efficiency of the large-area graphene films on a substrate with arbitrary thickness and rigidity, evidenced by scanning electron microscope (SEM) and atomic force microscope (AFM) images, Raman spectra, and various electrical characterizations. We also performed a theoretical multiscale simulation from continuum to atomic level to compare the mechanical stresses caused by the R2R and the hot-pressing methods, which also supports our conclusion. Consequently, we believe that the proposed hot-pressing method will be immediately useful for display and solar cell applications that currently require rigid and large substrates. PMID:22631604

  19. Substrate-free self-assembly approach toward large-area nanomembranes.

    PubMed

    Wang, Fei; Seo, Jung-Hun; Ma, Zhenqiang; Wang, Xudong

    2012-03-27

    Free-standing two-dimensional nanostrucutures, such as graphene and semiconductor nanomembranes (NMs) featuring their integration with flexible polymer substrates, address applications in which electronic devices need to be stretchable or conformally positioned to nonplanar surfaces. We report a surfactant-directed surface assembly approach to producing large-area NMs at the water-air interface. The NMs were produced by employing the surfactants as templates as well as incorporating them in the crystal structures. By using excess amount of sodium dodecylsulfate (SDS), a tightly packed monolayer of dodecylsulfate (DS) ion was formed and directed the crystallization of submillimeter-sized zinc hydroxy dodecylsulfate (ZHDS) single-crystalline NMs over the entire water surface. This free-standing NM can be readily transferred to an arbitrary substrate and converted to ZnO via heat treatment. A flexible thin-film transistor was also fabricated using the transferred NMs and demonstrated reasonably good n-type transport properties. This approach circumvented the needs of single-crystalline substrates for making large-area NMs from materials that do not possess a laminate structure. It is a low-cost and large-scale synthesis technique and has great potential in developing NMs and flexible devices from various functional materials that are not feasible by conventional selective etching or delamination approaches. PMID:22299624

  20. Upscaling of integrated photoelectrochemical water-splitting devices to large areas.

    PubMed

    Turan, Bugra; Becker, Jan-Philipp; Urbain, Félix; Finger, Friedhelm; Rau, Uwe; Haas, Stefan

    2016-01-01

    Photoelectrochemical water splitting promises both sustainable energy generation and energy storage in the form of hydrogen. However, the realization of this vision requires laboratory experiments to be engineered into a large-scale technology. Up to now only few concepts for scalable devices have been proposed or realized. Here we introduce and realize a concept which, by design, is scalable to large areas and is compatible with multiple thin-film photovoltaic technologies. The scalability is achieved by continuous repetition of a base unit created by laser processing. The concept allows for independent optimization of photovoltaic and electrochemical part. We demonstrate a fully integrated, wireless device with stable and bias-free operation for 40 h. Furthermore, the concept is scaled to a device area of 64 cm(2) comprising 13 base units exhibiting a solar-to-hydrogen efficiency of 3.9%. The concept and its successful realization may be an important contribution towards the large-scale application of artificial photosynthesis. PMID:27601181

  1. Power analysis for the design of a large area ultrasonic tactile touch panel

    NASA Astrophysics Data System (ADS)

    Yang, Yi; Lemaire-Semail, Betty; Giraud, Frédéric; Amberg, Michel; Zhang, Yuru; Giraud-Audine, Christophe

    2015-10-01

    Tactile interfaces are intuitive but lack of haptic feedback. One method to provide tactile feedback is to change the friction coefficient of the touch surface. Several small-size tactile devices have been developed to provide programmable friction coefficient based on the squeeze air film effect. This effect is produced by ultrasonic vibration of the tactile plate thanks to piezoceramics. In order to design larger embedded tactile feedback areas, a key issue is the power consumption. In this paper, we present the power analysis of a tactile device which is based on the squeeze film effect. We first investigate the source of power consumption by a series of measurements. Then, an analytical model is developed to estimate the power, which gives the conclusion that, when the vibration amplitude is constant, the power consumption is not related to the number of piezoelectric actuators. According to this result, we design a large area (198 mm × 138 mm) tactile plate with only eight piezoelectric actuators. Experimental results show that the power consumption of the large tactile plate is less than 2 W. Moreover, we also find that the power consumption of the large tactile plate was predictable with the measurement results from small plates with an average error of less than 10%.

  2. Microwave purification of large-area horizontally aligned arrays of single-walled carbon nanotubes.

    PubMed

    Xie, Xu; Jin, Sung Hun; Wahab, Muhammad A; Islam, Ahmad E; Zhang, Chenxi; Du, Frank; Seabron, Eric; Lu, Tianjian; Dunham, Simon N; Cheong, Hou In; Tu, Yen-Chu; Guo, Zhilin; Chung, Ha Uk; Li, Yuhang; Liu, Yuhao; Lee, Jong-Ho; Song, Jizhou; Huang, Yonggang; Alam, Muhammad A; Wilson, William L; Rogers, John A

    2014-01-01

    Recent progress in the field of single-walled carbon nanotubes (SWNTs) significantly enhances the potential for practical use of this remarkable class of material in advanced electronic and sensor devices. One of the most daunting challenges is in creating large-area, perfectly aligned arrays of purely semiconducting SWNTs (s-SWNTs). Here we introduce a simple, scalable, large-area scheme that achieves this goal through microwave irradiation of aligned SWNTs grown on quartz substrates. Microstrip dipole antennas of low work-function metals concentrate the microwaves and selectively couple them into only the metallic SWNTs (m-SWNTs). The result allows for complete removal of all m-SWNTs, as revealed through systematic experimental and computational studies of the process. As one demonstration of the effectiveness, implementing this method on large arrays consisting of ~20,000 SWNTs completely removes all of the m-SWNTs (~7,000) to yield a purity of s-SWNTs that corresponds, quantitatively, to at least to 99.9925% and likely significantly higher. PMID:25387684

  3. Large-area patterned substrates for micromagnetic actuation of superparamagnetic microbeads

    NASA Astrophysics Data System (ADS)

    Ouk, Minae; Beach, Geoffrey

    2014-03-01

    Superparamagnetic microbeads (SBs) are widely used to capture biological entities in a fluid environment. Chip-based magnetic actuation provides a means to transport SBs in lab-on-a-chip technologies. This is usually accomplished using the stray field from patterned magnetic microstructures, or domain walls in magnetic nanowires. However, lithographic patterning over a large area is costly and impractical using conventional techniques such as electron beam lithography. Here we use a simple floating-transfer technique for large-area self-assembly of polystyrene microspheres on a Si wafer to produce lithographic masks texturing a substrate. Hexagonal patterns are used as lift-off and etching masks to create magnetic dot and anti-dot arrays in CoFe thin films, with a size and spacing that can be tuned via sphere diameter and RIE etch time. Using a rotating magnetic fields, we show that these magnetically-patterned substrates can transport SBs across large distances on the wafer surface, opening the possibility to augment or replace microfluidic actuation for long distance transport. Supported by the MIT Deshpande Center.

  4. A strategy for GIS-based 3-D slope stability modelling over large areas

    NASA Astrophysics Data System (ADS)

    Mergili, M.; Marchesini, I.; Alvioli, M.; Metz, M.; Schneider-Muntau, B.; Rossi, M.; Guzzetti, F.

    2014-12-01

    GIS-based deterministic models may be used for landslide susceptibility mapping over large areas. However, such efforts require specific strategies to (i) keep computing time at an acceptable level, and (ii) parameterize the geotechnical data. We test and optimize the performance of the GIS-based, 3-D slope stability model r.slope.stability in terms of computing time and model results. The model was developed as a C- and Python-based raster module of the open source software GRASS GIS and considers the 3-D geometry of the sliding surface. It calculates the factor of safety (FoS) and the probability of slope failure (Pf) for a number of randomly selected potential slip surfaces, ellipsoidal or truncated in shape. Model input consists of a digital elevation model (DEM), ranges of geotechnical parameter values derived from laboratory tests, and a range of possible soil depths estimated in the field. Probability density functions are exploited to assign Pf to each ellipsoid. The model calculates for each pixel multiple values of FoS and Pf corresponding to different sliding surfaces. The minimum value of FoS and the maximum value of Pf for each pixel give an estimate of the landslide susceptibility in the study area. Optionally, r.slope.stability is able to split the study area into a defined number of tiles, allowing parallel processing of the model on the given area. Focusing on shallow landslides, we show how multi-core processing makes it possible to reduce computing times by a factor larger than 20 in the study area. We further demonstrate how the number of random slip surfaces and the sampling of parameters influence the average value of Pf and the capacity of r.slope.stability to predict the observed patterns of shallow landslides in the 89.5 km2 Collazzone area in Umbria, central Italy.

  5. A strategy for GIS-based 3-D slope stability modelling over large areas

    NASA Astrophysics Data System (ADS)

    Mergili, M.; Marchesini, I.; Alvioli, M.; Metz, M.; Schneider-Muntau, B.; Rossi, M.; Guzzetti, F.

    2014-08-01

    GIS-based deterministic models may be used for landslide susceptibility mapping over large areas. However, such efforts require specific strategies to (i) keep computing time at an acceptable level, and (ii) parameterize the geotechnical data. We test and optimize the performance of the GIS-based, 3-D slope stability model r.slope.stability in terms of computing time and model results. The model was developed as a C- and Python-based raster module of the open source software GRASS GIS and considers the 3-D geometry of the sliding surface. It calculates the factor of safety (FoS) and the probability of slope failure (Pf) for a number of randomly selected potential slip surfaces, ellipsoidal or truncated in shape. Model input consists of a DEM, ranges of geotechnical parameter values derived from laboratory tests, and a range of possible soil depths estimated in the field. Probability density functions are exploited to assign Pf to each ellipsoid. The model calculates for each pixel multiple values of FoS and Pf corresponding to different sliding surfaces. The minimum value of FoS and the maximum value of Pf for each pixel give an estimate of the landslide susceptibility in the study area. Optionally, r.slope.stability is able to split the study area into a defined number of tiles, allowing parallel processing of the model on the given area. Focusing on shallow landslides, we show how multi-core processing allows to reduce computing times by a factor larger than 20 in the study area. We further demonstrate how the number of random slip surfaces and the sampling of parameters influence the average value of Pf and the capacity of r.slope.stability to predict the observed patterns of shallow landslides in the 89.5 km2 Collazzone area in Umbria, central Italy.

  6. Testing of a Helium Loop Heat Pipe for Large Area Cryocooling

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Robinson, Franklin Lee

    2015-01-01

    Future NASA space telescopes and exploration missions require cryocooling of large areas such as optics, detector arrays, and cryogenic propellant tanks. One device that can potentially be used to provide closed-loop cryocooling is the cryogenic loop heat pipe (CLHP). A CLHP has many advantages over other devices in terms of reduced mass, reduced vibration, high reliability, and long life. A helium CLHP has been tested extensively in a thermal vacuum chamber using a cryocooler as the heat sink to characterize its transient and steady performance and verify its ability to cool large areas or components in the 3K temperature range. A copper plate with attached electrical heters was used to simulate the heat source, and heat was collected by the CLHP evaporator and transferred to the cryocooler for ultimate heat rejection. The helium CLHP thermal performance test included cool-down from the ambient temperature, startup, capillary limit, heat removal capability, rapid power changes, and long duration steady state operation. The helium CLHP demonstrated robust operation under steady state and transient conditions. The loop could be cooled from the ambient temperature to subcritical temperatures very effectively, and could start successfully without pre-conditioning by simply applying power to both the capillary pump and the evaporator plate. It could adapt to rapid changes in the heat load, and reach a new steady state very quickly. Heat removal between 10mW and 140mW was demonstrated, yielding a power turn down ratio of 14. When the CLHP capillary limit was exceeded, the loop could resume its normal function by reducing the power to the capillary pump. Steady state operations up to 17 hours at several heat loads were demonstrated. The ability of the helium CLHP to cool large areas was therefore successfully verified.

  7. Testing of a Helium Loop Heat Pipe for Large Area Cryocooling

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Robinson, Franklin

    2016-01-01

    Future NASA space telescopes and exploration missions require cryocooling of large areas such as optics, detector arrays, and cryogenic propellant tanks. One device that can potentially be used to provide closed-loop cryocooling is the cryogenic loop heat pipe (CLHP). A CLHP has many advantages over other devices in terms of reduced mass, reduced vibration, high reliability, and long life. A helium CLHP has been tested extensively in a thermal vacuum chamber using a cryocooler as the heat sink to characterize its transient and steady performance and verify its ability to cool large areas or components in the 3K temperature range. A copper plate with attached electrical heaters was used to simulate the heat source, and heat was collected by the CLHP evaporator and transferred to the cryocooler for ultimate heat rejection. The helium CLHP thermal performance test included cool-down from the ambient temperature, startup, capillary limit, heat removal capability, rapid power changes, and long duration steady state operation. The helium CLHP demonstrated robust operation under steady state and transient conditions. The loop could be cooled from the ambient temperature to subcritical temperatures very effectively, and could start successfully without pre-conditioning by simply applying power to both the capillary pump and the evaporator plate. It could adapt to rapid changes in the heat load, and reach a new steady state very quickly. Heat removal between 10mW and 140mW was demonstrated, yielding a power turn down ratio of 14. When the CLHP capillary limit was exceeded, the loop could resume its normal function by reducing the power to the capillary pump. Steady state operations up to 17 hours at several heat loads were demonstrated. The ability of the helium CLHP to cool large areas was therefore successfully verified.

  8. Simulating daily rainfall fields over large areas for collective risk estimation

    NASA Astrophysics Data System (ADS)

    Serinaldi, Francesco; Kilsby, Chris G.

    2014-05-01

    Large scale rainfall models are needed for collective risk estimation in flood insurance, infrastructure networks and water resource management applications. There is a lack of models which can provide simulations over large river basins (potentially multi-national) at appropriate spatial resolution (e.g., 5-25 km) that preserve both the local properties of rainfall (i.e., marginal distributions and temporal correlation) and the spatial structure of the field (i.e., the spatial dependence structure). In this study we describe a methodology which merges meta-Gaussian random fields and generalized additive models to simulate realistic rainfall fields at daily time scale over large areas. Unlike other techniques previously proposed in the literature, the suggested approach does not split the rainfall occurrence and intensity processes and resorts to a unique discrete-continuous distribution to reproduce the local properties of rainfall. This choice allows the use of a unique meta-Gaussian spatio-temporal random field substrate that is devised to reproduce the spatial properties and the short term temporal characteristics of the observed precipitation. The model is calibrated and tested on a 25 km gridded daily rainfall data set covering the 817 000 km2 of the Danube basin. Standard and ad hoc diagnostics highlight the overall good performance over the whole range of rainfall values at multiple scales of spatio-temporal aggregation with particular attention to extreme values. Moreover, the modular structure of the model allows for refinements, adaptation to different areas and the introduction of exogenous forcing variables, thus making it a valuable tool for classical hydrologic analyses as well as for new challenges of network and reinsurance risk assessment over extensive areas.

  9. The geomorphological features of a large scale deep-seated landslide in the Luchang area, Taiwan

    NASA Astrophysics Data System (ADS)

    Huang, Ming-Wan; Liao, Jyh-Jong; Pan, Yii-Wen

    2016-04-01

    Landslides events are frequently induced by high-intensity precipitation and active tectonic in Taiwan. Several catastrophic deep-seated landslides have been occurred in past few decades. The pre-existing landslides are the potential sites to occur again. The geomorphology features could provide their important information in reflection of landslide activity. The large scale deep-seated landslide of Luchang locates in the mountain area of Miaoli County, west-northern Taiwan. The site is about 60 hectares in area and from west to east is comprised of a ridge (El. 1100~950 m), main scarp, terrace (El. 925~900 m), hilly slope (El. 900~700 m), and the Luchang River. The regional geology is mainly the middle Miocene sedimentary rock which composed of thick sandstone, interlayered sandstone and shale, and coal. The major structures include the Luchang fault and the Shibi anticline, which the location of the former is approximately coincidental to the Luchang River and the latter is approximately coincidental to the ridge. In this study, we identify the geomorphology features by viewing stereo pairs of aerial photographs and examine in the field. UAV (Unmanned Aerial Vehicle) is adopted to assist in unreachable area. Several clear topographic features including scarps, anti-slopes, bulges, etc. are observed in this site. Active bedrock incision has caused many slope collapsed in the Luchang River, which could possibly be the important factors affecting the stability of this site. We also compared the topographic changes through the chronological aerial photographs. The topographic changes likely include several small-scale landslides. The preliminary evolution model of the large scale landslide is proposed in this study. The results help us to evaluate the recurrence potential of a large scale deep-seated landslide.

  10. GLAST: Exploring Nature's Highest Energy Processes with the Gamma-ray Large Area Space Telescope

    NASA Technical Reports Server (NTRS)

    Digel, Seth; Myers, J. D.; White, Nicholas E. (Technical Monitor)

    2001-01-01

    The Gamma-ray Large Area Space Telescope (GLAST) is an international and multi-agency space mission that will study the cosmos in the energy range 10 keV-300 GeV. Several successful exploratory missions in gamma-ray astronomy led to the Energetic Gamma Ray Experiment Telescope (EGRET) instrument on the Compton Gamma Ray Observatory (CGRO). Launched in 1991, EGRET made the first complete survey of the sky in the 30 MeV-10 GeV range. EGRET showed the high-energy gamma-ray sky to be surprisingly dynamic and diverse, with sources ranging from the sun and moon to massive black holes at large redshifts. Most of the gamma-ray sources detected by EGRET remain unidentified. In light of the discoveries with EGRET, the great potential of the next generation gamma-ray telescope can be appreciated. GLAST will have an imaging gamma-ray telescope vastly more capable than instruments flown previously, as well as a secondary instrument to augment the study of gamma-ray bursts. The main instrument, the Large Area Telescope (LAT), will have superior area, angular resolution, field of view, and deadtime that together will provide a factor of 30 or more advance in sensitivity, as well as provide capability for study of transient phenomena. The GLAST Burst Monitor (GBM) will have a field of view several times larger than the LAT and will provide spectral coverage of gamma-ray bursts that extends from the lower limit of the LAT down to 10 keV. The basic parameters of the GBM are compared to those of the Burst and Transient Source Experiment (BATSE) instrument on CGRO in Table 1-2. With the LAT and GBM, GLAST will be a flexible observatory for investigating the great range of astrophysical phenomena best studied in high-energy gamma rays. NASA plans to launch GLAST in late 2005.

  11. TFT-Based Active Pixel Sensors for Large Area Thermal Neutron Detection

    NASA Astrophysics Data System (ADS)

    Kunnen, George

    Due to diminishing availability of 3He, which is the critical component of neutron detecting proportional counters, large area flexible arrays are being considered as a potential replacement for neutron detection. A large area flexible array, utilizing semiconductors for both charged particle detection and pixel readout, ensures a large detection surface area in a light weight rugged form. Such a neutron detector could be suitable for deployment at ports of entry. The specific approach used in this research, uses a neutron converter layer which captures incident thermal neutrons, and then emits ionizing charged particles. These ionizing particles cause electron-hole pair generation within a single pixel's integrated sensing diode. The resulting charge is then amplified via a low-noise amplifier. This document begins by discussing the current state of the art in neutron detection and the associated challenges. Then, for the purpose of resolving some of these issues, recent design and modeling efforts towards developing an improved neutron detection system are described. Also presented is a low-noise active pixel sensor (APS) design capable of being implemented in low temperature indium gallium zinc oxide (InGaZnO) or amorphous silicon (a-Si:H) thin film transistor process compatible with plastic substrates. The low gain and limited scalability of this design are improved upon by implementing a new multi-stage self-resetting APS. For each APS design, successful radiation measurements are also presented using PiN diodes for charged particle detection. Next, detection array readout methodologies are modeled and analyzed, and use of a matched filter readout circuit is described as well. Finally, this document discusses detection diode integration with the designed TFT-based APSs.

  12. Self-consistent electrodynamics of large-area high-frequency capacitive plasma discharge

    SciTech Connect

    Chen Zhigang; Rauf, Shahid; Collins, Ken

    2010-10-15

    Capacitively coupled plasmas (CCPs) generated using high frequency (3-30 MHz) and very high frequency (30-300 MHz) radio-frequency (rf) sources are used for many plasma processing applications including thin film etching and deposition. When chamber dimensions become commensurate with the effective rf wavelength in the plasma, electromagnetic wave effects impose a significant influence on plasma behavior. Because the effective rf wavelength in plasma depends upon both rf and plasma process conditions (e.g., rf power and gas pressure), a self-consistent model including both the rf power delivery system and the plasma discharge is highly desirable to capture a more complete physical picture of the plasma behavior. A three-dimensional model for self-consistently studying both electrodynamic and plasma dynamic behavior of large-area (Gen 10, >8 m{sup 2}) CCP is described in this paper. This model includes Maxwell's equations and transport equations for charged and neutral species, which are coupled and solved in the time domain. The complete rf plasma discharge chamber including the rf power delivery subsystem, rf feed, electrodes, and the plasma domain is modeled as an integrated system. Based on this full-wave solution model, important limitations for processing uniformity imposed by electromagnetic wave propagation effects in a large-area CCP (3.05x2.85 m{sup 2} electrode size) are studied. The behavior of H{sub 2} plasmas in such a reactor is examined from 13.56 to 200 MHz. It is shown that various rectangular harmonics of electromagnetic fields can be excited in a large-area rectangular reactor as the rf or power is increased. The rectangular harmonics can create not only center-high plasma distribution but also high plasma density at the corners and along the edges of the reactor.

  13. Yb-doped large mode area fibers with depressed clad and dopant confinement

    NASA Astrophysics Data System (ADS)

    Roy, Vincent; Paré, Claude; Laperle, Pierre; Desbiens, Louis; Taillon, Yves

    2016-03-01

    Large mode area fibers with depressed-index cladding layer and confinement of rare-earth dopants can provide effective suppression of high-order modes. A polarization-maintaining Yb-doped double-clad fiber with 35/250 μm core/clad diameter has been fabricated from conventional methods according to this design. The fiber which has an effective mode area close to 500 μm2 yields near diffraction-limited output with beam quality factor M2 close to 1.1 when tested as a power amplifier with a coherent seed light source. Beam pointing measurements provide further evidence for near single-mode behavior as the pointing fluctuations are shown to be negligible once the fiber is coiled to a given diameter.

  14. Large-area, uniform white light LED source on a flexible substrate.

    PubMed

    Sher, Chin-Wei; Chen, Kuo-Ju; Lin, Chien-Chung; Han, Hau-Vei; Lin, Huang-Yu; Tu, Zong-Yi; Tu, Hsien-Hao; Honjo, Keiji; Jiang, Hsin-Yi; Ou, Sin-Liang; Horng, Ray-Hua; Li, Xiuling; Fu, Chien-Chung; Kuo, Hao-Chung

    2015-09-21

    This study demonstrates the flexible white LED structure with high lumen efficiency and uniform optical performance for neutral white and warm white CCT. Flip-chip LEDs were attached on a polyimide substrate with copper strips as electrical and thermal conduction paths. Yellow phosphors are mixed with polydimenthysiloxane (PDMS) to provide mechanical support and flexibility. The light efficiency of this device can reach 120 lm/W and 85% of light output uniformity of the emission area can be achieved. Moreover, the optical simulation is employed to evaluate various designs of this flexible film in order to obtain uniform output. Both the pitch between the individual devices and the thickness of the phosphor film are calculated for optimization purpose. This flexible white LED with high lumen efficiency and good reliability is suitable for the large area fixture in the general lighting applications. PMID:26406747

  15. Performance evaluation of new large-area avalanche photodiodes for scintillation spectroscopy

    NASA Astrophysics Data System (ADS)

    James, K. M.; Masterson, M. J.; Farrell, R.

    Avalanche photodiodes (APD's) appear promising for certain applications as a solid state replacement for the photomultiplier tube. The increase in leakage current and capacitance noise with device active area has in the past kept the size of commercially available devices to less than 1 mm (exp 2). Recent advances in fabrication technology have, however, resulted in relatively low noise devices of up to 1 inch in diameter. We have recently evaluated the performance as scintillation spectroscopy detectors of two commercial large area avalanche photodiodes. These APD's exhibit exceptional performance: at 662 KeV a 1 inch diameter device coupled to a CsI(Tl) scintillator and operating at room temperature yielded 6.9 pct. resolution and a 1 cm device coupled to CsI(Tl) and cooled to 260 K gave 4.4 pct. resolution, which is believed to be the best resolution ever recorded for a scintillation spectrometer.

  16. Large area focusing collector for the observation of cosmic X rays.

    NASA Technical Reports Server (NTRS)

    Gorenstein, P.; Decaprio, A.; Chase, R.; Harris, B.

    1973-01-01

    A large area focusing X-ray collector constructed for a sounding rocket is described. The instrument consists of nested reflecting plates that are curved slightly in one dimension to form a set of parabolas with a common focus. An array of plates such as the one in the sounding rocket focuses a parallel beam of X-rays to a line. The reflecting surfaces are commercial float glass with an evaporated metallic coating such as gold or nickel. With a gold coating, the effective area of the rocket collector is about 250 sq cm for 0.3 keV X rays and about 150 sq cm at 1.2 keV. Its angular resolution is a few arc minutes and field of view is about plus or minus .75 deg (full width at half maximum). The collector performed successfully during a sounding rocket flight.

  17. Large area silicon drift detectors for x-rays -- New results

    SciTech Connect

    Iwanczyk, J.S.; Patt, B.E.; Tull, C.R.; Segal, J.D.; Kenney, C.J.; Bradley, J.; Hedman, B.; Hodgson, K.O.

    1999-06-01

    Large area silicon drift detectors, consisting of 8 mm and 12 mm diameter hexagons, were fabricated on 0.35 mm thick high resistivity n-type silicon. An external FET and a low-noise charge sensitive preamplifier were used for testing the prototype detectors. The detector performance was measured in the range {minus}75 to 25 C using Peltier cooling, and from 0.125 to 6 {micro}s amplifier shaping time. Measured energy resolutions were 159 eV FWHM and 263 eV FWHM for the 0.5 cm{sup 2} and 1 cm{sup 2} detectors, respectively (at 5.9 keV, {minus}75 C, 6 {micro}s shaping time). The uniformity of the detector response over the entire active area (measured using 560 nm light) was <0.5%.

  18. Extending single mode performance of all-solid large-mode-area single trench fiber.

    PubMed

    Jain, D; Jung, Y; Nunez-Velazquez, M; Sahu, J K

    2014-12-15

    We report a novel "single trench fiber" design for mode area scaling of the fundamental mode while offering effective single mode operation for a compact fiber laser device. This fiber design allows very high suppression of the higher order modes by offering high loss and power delocalization. It has the advantages of low cost and easy fabrication thanks to all solid fiber design, cylindrical symmetry, and higher refractive index of core as that of the cladding. A Yb-doped single trench fiber with a 40 µm core diameter has been fabricated from modified chemical vapor deposition process in conjunction with solution-doping offering an effective mode area of as large as ~1,000 µm(2) at 1,060 nm for the bend radius of 20 cm. Detailed characterizations confirm a robust single mode behavior of the fiber. Comparative analysis with other fiber designs shows significant performance enhancement of effective single mode operation suitable for fiber laser applications. PMID:25607057

  19. Large-area few-layer MoS2 deposited by sputtering

    NASA Astrophysics Data System (ADS)

    Huang, Jyun-Hong; Chen, Hsing-Hung; Liu, Pang-Shiuan; Lu, Li-Syuan; Wu, Chien-Ting; Chou, Cheng-Tung; Lee, Yao-Jen; Li, Lain-Jong; Chang, Wen-Hao; Hou, Tuo-Hung

    2016-06-01

    Direct magnetron sputtering of transition metal dichalcogenide targets is proposed as a new approach for depositing large-area two-dimensional layered materials. Bilayer to few-layer MoS2 deposited by magnetron sputtering followed by post-deposition annealing shows superior area scalability over 20 cm2 and layer-by-layer controllability. High crystallinity of layered MoS2 was confirmed by Raman, photo-luminescence, and transmission electron microscopy analysis. The sputtering temperature and annealing ambience were found to play an important role in the film quality. The top-gate field-effect transistor by using the layered MoS2 channel shows typical n-type characteristics with a current on/off ratio of approximately 104. The relatively low mobility is attributed to the small grain size of 0.1–1 μm with a trap charge density in grain boundaries of the order of 1013 cm–2.

  20. Fiber Bragg grating in large-mode-area fiber for high power fiber laser applications.

    PubMed

    Mohammed, Waleed; Gu, Xijia

    2010-10-01

    Fiber Bragg gratings (FBGs) are indispensable components in the design of monolithic high-power fiber lasers. As the laser power scales up, the adoption of larger-mode-area fibers with high V numbers poses new challenges for FBG design and fabrication. In this paper, we present the simulation, fabrication, and measurement of the FBGs inscribed on large-mode-area fibers. The simulation used the T-matrix approach to calculate the spectral response of the FBG that matched well with the measured spectra. The observed fringes in the reflection spectrum are explained by the interference between the low-order modes that were also confirmed with the simulation. Some unique features of the FBG and their potential applications are discussed. PMID:20885465

  1. Low-impedance internal linear inductive antenna for large-area flat panel display plasma processing

    SciTech Connect

    Kim, K.N.; Jung, S.J.; Lee, Y.J.; Yeom, G.Y.; Lee, S.H.; Lee, J.K.

    2005-03-15

    An internal-type linear inductive antenna, that is, a double-comb-type antenna, was developed for a large-area plasma source having the size of 1020 mmx830 mm, and high density plasmas on the order of 2.3x10{sup 11} cm{sup -3} were obtained with 15 mTorr Ar at 5000 W of inductive power with good plasma stability. This is higher than that for the conventional serpentine-type antenna, possibly due to the low impedance, resulting in high efficiency of power transfer for the double-comb antenna type. In addition, due to the remarkable reduction of the antenna length, a plasma uniformity of less than 8% was obtained within the substrate area of 880 mmx660 mm at 5000 W without having a standing-wave effect.

  2. Large-Eddy Simulation of plume dispersion within various actual urban areas

    NASA Astrophysics Data System (ADS)

    Nakayama, H.; Jurcakova, K.; Nagai, H.

    2013-02-01

    Plume dispersion of hazardous materials within urban area resulting from accidental or intentional releases is of great concern to public health. Many researchers have developed local-scale atmospheric dispersion models using building-resolving computational fluid dynamics. However, an important issue is encountered when determining a reasonable domain size of the computational model in order to capture concentration distribution patterns influenced by urban surface geometries. In this study, we carried out Large-Eddy Simulations (LES) of plume dispersion within various urban areas with a wide range of obstacle density and building height variability. The difference of centerline mean and r.m.s. concentration distributions among various complex urban surface geometries becomes small for downwind distances from the point source greater than 1.0 km. From these results, it can be concluded that a length of a computational model should be at least 1.0 km from a point source.

  3. Large area silicon drift detectors for x-rays -- New results

    SciTech Connect

    Iwanczyk, J.S.; Patt, B.E.; Tull, C.R.; Segal, J.D.; Kenney, C.J.; Bradley, J.; Hedman, B.; Hodgson, K.O.

    1998-12-31

    Large area silicon drift detectors, consisting of 8 mm and 12 mm diameter hexagons, were fabricated on 0.35 mm thick high resistivity n-type silicon. An external FET and a low-noise charge sensitive preamplifier were used for testing the prototype detectors. The detector performance was measured in the range 75 to 25 C using Peltier cooling, and from 0.125 to 6 {micro}s amplifier shaping time. Measured energy resolutions were 159 eV FWHM and 263 eV FWHM for the 0.5 cm{sup 2} and 1 cm{sup 2} detectors, respectively (at 5.9 keV, {minus}75 C, 6 {micro}s shaping time). The uniformity of the detector response over the entire active area (measured using 560 nm light) was < 0.5%.

  4. Health impacts of large releases of radionuclides. The fate and impact of radiocontaminants in urban areas.

    PubMed

    Roed, J; Andersson, K G; Lange, C

    1997-01-01

    The Chernobyl accident made it clear that the contaminants released after a severe nuclear accident may spread over large areas, and thereby form a significant external radiation hazard in areas of high population density. Since then, the weathering effects on the deposited radiocontaminants (essentially radiocaesium) have been followed on different types of surface in urban, suburban and industrial areas in order to enable an estimation of the long-term impact of such events. Analytical expressions have been derived for the typical behaviour of radiocaesium on the different surfaces, and dose measurements and calculations for different urban environments have pinpointed which surfaces generally contribute most to the dose and consequently are most important to clean. At this point, after nearly a decade, the dose rate from horizontal pavements has decreased by at least a factor of 10, whereas the dose rate from an area of soil or a roof has generally only been halved. The contamination on walls is the most persistent: it has only decreased by 10-20%. PMID:9339313

  5. Long-period ocean-bottom motions in the source areas of large subduction earthquakes.

    PubMed

    Nakamura, Takeshi; Takenaka, Hiroshi; Okamoto, Taro; Ohori, Michihiro; Tsuboi, Seiji

    2015-01-01

    Long-period ground motions in plain and basin areas on land can cause large-scale, severe damage to structures and buildings and have been widely investigated for disaster prevention and mitigation. However, such motions in ocean-bottom areas are poorly studied because of their relative insignificance in uninhabited areas and the lack of ocean-bottom strong-motion data. Here, we report on evidence for the development of long-period (10-20 s) motions using deep ocean-bottom data. The waveforms and spectrograms demonstrate prolonged and amplified motions that are inconsistent with attenuation patterns of ground motions on land. Simulated waveforms reproducing observed ocean-bottom data demonstrate substantial contributions of thick low-velocity sediment layers to development of these motions. This development, which could affect magnitude estimates and finite fault slip modelling because of its critical period ranges on their estimations, may be common in the source areas of subduction earthquakes where thick, low-velocity sediment layers are present. PMID:26617193

  6. Large-area silicon photomultipliers as readout candidates for the GlueX experiment

    NASA Astrophysics Data System (ADS)

    Papandreou, Zisis; Janzen, Kathryn; Lolos, George; Semenov, Andrei; Zorn, Carl

    2009-10-01

    The core mission of the GlueX experiment involves a search for exotic hybrid mesons as evidence of gluonic excitations in an effort to understand confinement in QCD. A key subsystem of the GlueX detector is the electromagnetic barrel calorimeter (BCAL) located inside a 2.5 Tesla superconducting solenoid. Due to this arrangement, light sensors are required that can operate in the high magnetic field environment. Among these, Silicon photomultipliers (SiPMs) are very promising candidates as front-end detectors. To date, routine use of SiPMs has been limited to those with an active area of a few mm^2. GlueX will require 2300 large-area SiPMs, each composed of sixteen 3x3 mm^2 cells arranged in a 4x4 array for a total area of ˜144 mm^2 per array. This has placed the GlueX collaboration in the unique position of driving the technology for such larger-area sensors. In this talk I will present tests carried out at Regina and Jefferson Lab regarding performance parameters of prototype SiPM arrays and their micro subcomponents.

  7. The linkage between immigration and internal migration in large metropolitan areas in the United States.

    PubMed

    Wright, R A; Ellis, M; Reibel, M

    1997-04-01

    "This paper investigates the relationship between the internal migration of native-born workers and flows of immigrants to the United States using the 1980 and 1990 U.S. Census Bureau microsamples.... Based on the estimation of three sets of regression models for five overlapping samples of the largest metropolitan areas in the United States and five mutually exclusive segments of the labor force, this analysis shows that the finding of a significant linkage between internal migration and immigration depends critically on the empirical experiment used. In direct opposition to previous published research, we conclude that net migration of the native born for metropolitan areas is either positively related or unrelated to immigration. Our models show that the net migration loss of unskilled native workers from metropolitan areas is probably a function of those cities' population size rather than immigrant flow to them. We conclude that the net migration loss of native-born workers from large metropolitan areas is more likely the result of industrial restructuring than of competition with immigrants." PMID:12292531

  8. Long-period ocean-bottom motions in the source areas of large subduction earthquakes

    PubMed Central

    Nakamura, Takeshi; Takenaka, Hiroshi; Okamoto, Taro; Ohori, Michihiro; Tsuboi, Seiji

    2015-01-01

    Long-period ground motions in plain and basin areas on land can cause large-scale, severe damage to structures and buildings and have been widely investigated for disaster prevention and mitigation. However, such motions in ocean-bottom areas are poorly studied because of their relative insignificance in uninhabited areas and the lack of ocean-bottom strong-motion data. Here, we report on evidence for the development of long-period (10–20 s) motions using deep ocean-bottom data. The waveforms and spectrograms demonstrate prolonged and amplified motions that are inconsistent with attenuation patterns of ground motions on land. Simulated waveforms reproducing observed ocean-bottom data demonstrate substantial contributions of thick low-velocity sediment layers to development of these motions. This development, which could affect magnitude estimates and finite fault slip modelling because of its critical period ranges on their estimations, may be common in the source areas of subduction earthquakes where thick, low-velocity sediment layers are present. PMID:26617193

  9. Large area x-ray collimator-the zone plate approach.

    PubMed

    Menz, Benedikt; Braig, Christoph; Bräuninger, Heinrich; Burwitz, Vadim; Hartner, Gisela; Predehl, Peter

    2015-09-10

    One question of particular interest in the measurement of x-ray imaging optics for space telescopes concerns the characteristics of the point spread function (PSF) in orbit and the focal length for an infinite source distance. In order to measure such a PSF, a parallel x-ray beam with a diameter of several centimeters to meters is required. For this purpose a large area transmission x-ray zone plate (ZP) for collimating x-ray beams has been designed, built, and tested. Furthermore we present a setup to determine large-scale aberrations of the collimated beam. From x-ray measurements we obtain an upper limit for the angular resolution of ±0.2 arc sec and a first-order diffraction efficiency of ≈13%. These results show that it is possible to use a ZP as a collimator for the PANTER x-ray test facility. PMID:26368954

  10. Noise in large-area CrlS Hg1-xCdxTe photovoltaic detectors

    NASA Astrophysics Data System (ADS)

    D'Souza, Arvind I.; Stapelbroek, Maryn G.; Masterjohn, Stacy A.; Wijewarnasuriya, Priyalal S.; DeWames, Roger E.; Smith, David S.; Ehlert, John C.

    2003-01-01

    The National Polar-orbiting Operational Environmental Satellite System (NPOESS) Cross-track Infrared Sounder (CrIS) is a Fourier Transform interferometric sensor that measures earth radiances at high spectral resolution. Algorithms use the data to provide pressure, temperature, and moisture profiles of the atmosphere. The CrIS instrument contains photovoltaic detectors with spectral cut-offs denoted by SWIR, MWIR and LWIR. The CrIS instrument requires large-area, photovoltaic detectors with state-of-art detector performance at temperatures attainable with passive cooling. For example, detectors as large as 1 mm in diameter are required. To address these needs, Molecular Beam Epitaxy (MBE) is used to grow the appropriate bandgap n-type Hg1-xCdxTe on lattice matched CdZnTe. The p-side is obtained via arsenic implantation followed by appropriate annealing steps.

  11. Large area CMOS bio-pixel array for compact high sensitive multiplex biosensing.

    PubMed

    Sandeau, Laure; Vuillaume, Cassandre; Contié, Sylvain; Grinenval, Eva; Belloni, Federico; Rigneault, Hervé; Owens, Roisin M; Fournet, Margaret Brennan

    2015-02-01

    A novel CMOS bio-pixel array which integrates assay substrate and assay readout is demonstrated for multiplex and multireplicate detection of a triplicate of cytokines with single digit pg ml(-1) sensitivities. Uniquely designed large area bio-pixels enable individual assays to be dedicated to and addressed by single pixels. A capability to simultaneously measure a large number of targets is provided by the 128 available pixels. Chemiluminescent assays are carried out directly on the pixel surface which also detects the emitted chemiluminescent photons, facilitating a highly compact sensor and reader format. The high sensitivity of the bio-pixel array is enabled by the high refractive index of silicon based pixels. This in turn generates a strong supercritical angle luminescence response significantly increasing the efficiency of the photon collection over conventional farfield modalities. PMID:25490928

  12. A large area cosmic muon detector located at Ohya stone mine

    NASA Technical Reports Server (NTRS)

    Nii, N.; Mizutani, K.; Aoki, T.; Kitamura, T.; Mitsui, K.; Matsuno, S.; Muraki, Y.; Ohashi, Y.; Okada, A.; Kamiya, Y.

    1985-01-01

    The chemical composition of the primary cosmic rays between 10 to the 15th power eV and 10 to the 18th power eV were determined by a Large Area Cosmic Muon Detector located at Ohya stone mine. The experimental aims of Ohya project are; (1) search for the ultra high-energy gamma-rays; (2) search for the GUT monopole created by Big Bang; and (3) search for the muon bundle. A large number of muon chambers were installed at the shallow underground near Nikko (approx. 100 Km north of Tokyo, situated at Ohya-town, Utsunomiya-city). At the surface of the mine, very fast 100 channel scintillation counters were equipped in order to measure the direction of air showers. These air shower arrays were operated at the same time, together with the underground muon chamber.

  13. Ytterbium-doped large-mode-area silica fiber fabricated by using chelate precursor doping technique.

    PubMed

    Shi, Tengfei; Zhou, Zhiguang; Ni, Li; Xiao, Xusheng; Zhan, Huan; Zhang, Aidong; Lin, Aoxiang

    2014-05-20

    We reported on a highly effective chelate precursor doping technique for Yb-doped large-mode-area (LMA) fiber manufacture. By accurately controlling the evaporation temperature and flow rate of carrier gas, the chelate precursor doping technique is capable of making Yb-doped LMA silica fiber with good uniformity free of center dip, low numerical aperture of ~0.056, large preform core size of 4.46 mm, and appropriate cladding absorption of 1.17  dB/m at 976.4 nm. Based on a single-end-pump all-fiber oscillator laser setup, the laser output at 1080 nm reached 700 W with slope efficiency of 54.2%. PMID:24922203

  14. An advanced open-path atmospheric pollution monitor for large areas

    SciTech Connect

    Taylor, L.

    1995-10-01

    Large amounts of toxic waste materials, generated in manufacturing fuel for nuclear reactors, are stored in tanks buried over large areas at DOE sites. Flammable and hazardous gases are continually generated by chemical reactions in the waste materials. To prevent explosive concentrations of these gases, the gases are automatically vented to the atmosphere when the pressure exceeds a preset value. Real-time monitoring of the atmosphere above the tanks with automatic alarming is needed to prevent exposing workers to unsafe conditions when venting occurs. This report describes the development of a monitor which can measure concentrations of hazardous gases over ranges as long as 4km. The system consists of a carbon dioxide laser combined with an acousto-optic tunable filter.

  15. Large mode area aperiodic fiber designs for robust singlemode emission under high thermal load

    NASA Astrophysics Data System (ADS)

    Dauliat, Romain; Coscelli, Enrico; Poli, Federica; Darwich, Dia; Benoît, Aurélien; Jamier, Raphaël.; Schuster, Kay; Grimm, Stephan; Cucinotta, Annamaria; Selleri, Stefano; Salin, François; Roy, Philippe

    2015-05-01

    In this paper, we investigate the potential of various large mode area fibers under thermal load, that is the state-of-the-art air-silica large pitch fibers, as well as the recently devised symmetry-reduced photonic crystal fiber and aperiodic all-solid by carefully considering the degrees of freedom offered all along the fiber fabrication. This work aims to discuss the mode filtering ability of these structures in regard to the power scaling and to confirm their potential for robust singlemode operation at high power level. Structural principles contributing to improve their performances such as the impact of air holes / solid inclusions size will be presented. We also intend to establish that the range of average absorbed/output power for which a robust singlemode operation is available can be shifted to fulfill user requests in term of power range.

  16. The large-area hybrid-optics CLAS12 RICH detector: Tests of innovative components

    SciTech Connect

    Contalbrigo, M; Baltzell, N; Benmokhtar, F; Barion, L; Cisbani, E; El Alaoui, A; Hafidi, K; Hoek, M; Kubarovsky, V; Lagamba, L; Lucherini, V; Malaguti, R; Mirazita, M; Montgomery, R; Movsisyan, A; Musico, P; Orecchini, D; Orlandi, A; Pappalardo, L L; Pereira, S; Perrino, R; Phillips, J; Pisano, S; Rossi, P; Squerzanti, S; Tomassini, S; Turisini, M; Viticchiè, A

    2014-07-01

    A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Lab to study the 3D nucleon structure in the yet poorly explored valence region by deep-inelastic scattering, and to perform precision measurements in hadronization and hadron spectroscopy. The adopted solution foresees a novel hybrid optics design based on an aerogel radiator, composite mirrors and densely packed and highly segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). The preliminary results of individual detector component tests and of the prototype performance at test-beams are reported here.

  17. Large-Area Reflective Infrared Filters for Millimeter/Sub-mm Telescopes

    NASA Astrophysics Data System (ADS)

    Ahmed, Z.; Grayson, J. A.; Thompson, K. L.; Kuo, C.-L.; Brooks, G.; Pothoven, T.

    2014-09-01

    Ground-based millimeter and sub-millimeter telescopes are attempting to image the sky with ever-larger cryogenically-cooled bolometer arrays, but face challenges in mitigating the infrared loading accompanying large apertures. Absorptive infrared filters supported by mechanical coolers scale insufficiently with aperture size. Reflective metal-mesh filters placed behind the telescope window provide a scalable solution in principle, but have been limited by photolithography constraints to diameters under 300 mm. We present laser etching as an alternate technique to photolithography for fabrication of large-area reflective filters, and show results from lab tests of 500-mm-diameter filters. Filters with up to 700-mm diameter can be fabricated using laser etching with existing capability.

  18. Thin film cadmium telluride charged particle sensors for large area neutron detectors

    SciTech Connect

    Murphy, J. W.; Smith, L.; Calkins, J.; Mejia, I.; Cantley, K. D.; Chapman, R. A.; Quevedo-Lopez, M.; Gnade, B.; Kunnen, G. R.; Allee, D. R.; Sastré-Hernández, J.; Contreras-Puente, G.; Mendoza-Pérez, R.

    2014-09-15

    Thin film semiconductor neutron detectors are an attractive candidate to replace {sup 3}He neutron detectors, due to the possibility of low cost manufacturing and the potential for large areas. Polycrystalline CdTe is found to be an excellent material for thin film charged particle detectors—an integral component of a thin film neutron detector. The devices presented here are characterized in terms of their response to alpha and gamma radiation. Individual alpha particles are detected with an intrinsic efficiency of >80%, while the devices are largely insensitive to gamma rays, which is desirable so that the detector does not give false positive counts from gamma rays. The capacitance-voltage behavior of the devices is studied and correlated to the response due to alpha radiation. When coupled with a boron-based neutron converting material, the CdTe detectors are capable of detecting thermal neutrons.

  19. The large-area hybrid-optics CLAS12 RICH detector: Tests of innovative components

    NASA Astrophysics Data System (ADS)

    Contalbrigo, M.; Baltzell, N.; Benmokhtar, F.; Barion, L.; Cisbani, E.; El Alaoui, A.; Hafidi, K.; Hoek, M.; Kubarovsky, V.; Lagamba, L.; Lucherini, V.; Malaguti, R.; Mirazita, M.; Montgomery, R.; Movsisyan, A.; Musico, P.; Orecchini, D.; Orlandi, A.; Pappalardo, L. L.; Pereira, S.; Perrino, R.; Phillips, J.; Pisano, S.; Rossi, P.; Squerzanti, S.; Tomassini, S.; Turisini, M.; Viticchiè, A.

    2014-12-01

    A large area ring-imaging Cherenkov detector has been designed to provide clean hadron identification capability in the momentum range from 3 GeV/c to 8 GeV/c for the CLAS12 experiments at the upgraded 12 GeV continuous electron beam accelerator facility of Jefferson Lab to study the 3D nucleon structure in the yet poorly explored valence region by deep-inelastic scattering, and to perform precision measurements in hadronization and hadron spectroscopy. The adopted solution foresees a novel hybrid optics design based on an aerogel radiator, composite mirrors and densely packed and highly segmented photon detectors. Cherenkov light will either be imaged directly (forward tracks) or after two mirror reflections (large angle tracks). The preliminary results of individual detector component tests and of the prototype performance at test-beams are reported here.

  20. Evapotranspiration and runoff from large land areas: Land surface hydrology for atmospheric general circulation models

    NASA Technical Reports Server (NTRS)

    Famiglietti, J. S.; Wood, Eric F.

    1993-01-01

    A land surface hydrology parameterization for use in atmospheric GCM's is presented. The parameterization incorporates subgrid scale variability in topography, soils, soil moisture and precipitation. The framework of the model is the statistical distribution of a topography-soils index, which controls the local water balance fluxes, and is therefore taken to represent the large land area. Spatially variable water balance fluxes are integrated with respect to the topography-soils index to yield our large topography-soils distribution, and interval responses are weighted by the probability of occurrence of the interval. Grid square averaged land surface fluxes result. The model functions independently as a macroscale water balance model. Runoff ratio and evapotranspiration efficiency parameterizations are derived and are shown to depend on the spatial variability of the above mentioned properties and processes, as well as the dynamics of land surface-atmosphere interactions.