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Sample records for observed large circular

  1. Accelerator Considerations of Large Circular Colliders

    NASA Astrophysics Data System (ADS)

    Chao, Alex

    As we consider the tremendous physics reaches of the big future circular electron-positron and proton-proton colliders, it might be advisable to keep a close track of what accelerator challenges they face. Good progresses are being made, and yet it is reported here that substantial investments in funding, manpower, as well as a long sustained time to the R&D efforts will be required in preparation to realize these dream colliders.

  2. Accelerator considerations of large circular colliders

    NASA Astrophysics Data System (ADS)

    Chao, Alex

    2016-07-01

    As we consider the tremendous physics reaches of the big future circular electron-positron and proton-proton colliders, it might be advisable to keep a close track of what accelerator challenges they face. Good progresses are being made, and yet it is reported here that substantial investments in funding, manpower, as well as a long sustained time to the R&D efforts will be required in preparation to realize these dream colliders.

  3. Large Scale Quantum Coherence of Nearly Circular Wavepackets

    SciTech Connect

    Reinhold, Carlos O; Yoshida, S.; Burgdorfer, J.; Wyker, B.; Mestayer, J. J.; Dunning, F. B.

    2009-01-01

    We demonstrate that the quantum coherence of mesoscopic very-high-n, n {approx} 305, Rydberg wave packets travelling along nearly circular orbits can be maintained on microsecond time scales corresponding to hundreds of classical orbital periods. The coherence is probed through collapses and revivals of periodic oscillations in the average electron position. The temporal interferences of spatially separated Schroedinger cat-like wave packets are also observed. A novel hybrid quantum-classical trajectory method is employed to simulate the wave packet dynamics.

  4. Large quasi-circular features beneath frost on Triton

    NASA Technical Reports Server (NTRS)

    Helfenstein, Paul; Veverka, Joseph; Mccarthy, Derek; Lee, Pascal; Hillier, John

    1992-01-01

    Specially processed Voyager 2 images of Neptune's largest moon, Triton, reveal three large quasi-circular features ranging in diameter from 280 to 935 km within Triton's equatorial region. The largest of these features contains a central irregularly shaped area of comparatively low albedo about 380 km in diameter, surrounded by crudely concentric annuli of higher albedo materials. None of the features exhibit significant topographic expression, and all appear to be primarily albedo markings. The features are located within a broad equatorial band of anomalously transparent frost that renders them nearly invisible at the large phase angles (alpha greater than 90 deg) at which Voyager obtained its highest resolution coverage of Triton. The features can be discerned at smaller phase angles (alpha = 66 deg) at which the frost only partially masks underlying albedo contrasts. The origin of the features is uncertain but may have involved regional cryovolcanic activity.

  5. Large quasi-circular features beneath frost on triton.

    PubMed

    Helfenstein, P; Veverka, J; McCarthy, D; Lee, P; Hillier, J

    1992-02-14

    Specially processed Voyager 2 images of Neptune's largest moon, Triton, reveal three large quasi-circular features ranging in diameter from 280 to 935 kilometers within Triton's equatorial region. The largest of these features contains a central, irregularly shaped area of comparatively low albedo about 380 kilometers in diameter, surrounded by crudely concentric annuli of higher albedo materials. None of the features exhibit significant topographic expression, and all appear to be primarily albedo markings. The features are located within a broad equatorial band of anomalously transparent frost that renders them nearly invisible at the large phase angles (alpha > 90 degrees ) at which Voyager obtained its highest resolution coverage of Triton. The features can be discerned at smaller phase angles (alpha = 66 degrees ) at which the frost only partially masks underlying albedo contrasts. The origin of the features is uncertain but may have involved regional cryovolcanic activity.

  6. Circular photogalvanic effect observed in silver-palladium film resistors

    NASA Astrophysics Data System (ADS)

    Mikheev, G. M.; Aleksandrov, V. A.; Saushin, A. S.

    2011-06-01

    The surface circular photogalvanic effect (CPGE) at a laser wavelength of 1064 nm was observed for the first time in silver-palladium resistors fabricated by a thick-film technology. The CPGE response was detected using the electrodes oriented parallel to the radiation incidence plane, for the laser beam obliquely incident onto the sample surface. The coefficient of the pulsed laser radiation power conversion into light-induced emf (with the polarity depending on the sign of the circular polarization) amounted to about 80 mV/MW for film dimensions of 0.02 × 20 × 20 mm and a load resistance of 50 Ω. The maximum absolute value of the conversion coefficient was observed for the angles of light incidence of ±60°.

  7. Microfabrication of large-area circular high-stress silicon nitride membranes for optomechanical applications

    NASA Astrophysics Data System (ADS)

    Serra, E.; Bawaj, M.; Borrielli, A.; Di Giuseppe, G.; Forte, S.; Kralj, N.; Malossi, N.; Marconi, L.; Marin, F.; Marino, F.; Morana, B.; Natali, R.; Pandraud, G.; Pontin, A.; Prodi, G. A.; Rossi, M.; Sarro, P. M.; Vitali, D.; Bonaldi, M.

    2016-06-01

    In view of the integration of membrane resonators with more complex MEMS structures, we developed a general fabrication procedure for circular shape SiNx membranes using Deep Reactive Ion Etching (DRIE). Large area and high-stress SiNx membranes were fabricated and used as optomechanical resonators in a Michelson interferometer, where Q values up to 1.3 × 106 were measured at cryogenic temperatures, and in a Fabry-Pérot cavity, where an optical finesse up to 50000 has been observed.

  8. Reading Materials in Large Type. Reference Circular No. 87-4.

    ERIC Educational Resources Information Center

    Library of Congress, Washington, DC. National Library Service for the Blind and Physically Handicapped.

    This circular provides information about reading materials in large type, i.e., materials set in type that is a minimum size of 14-point and, most commonly, 16- to 18-point size. Most of the materials listed are typeset, but a few are photographically enlarged conventionally printed books or typewritten materials prepared using a large-print…

  9. Large-eddy simulation of turbulent circular jet flows

    SciTech Connect

    Jones, S. C.; Sotiropoulos, F.; Sale, M. J.

    2002-07-01

    This report presents a numerical method for carrying out large-eddy simulations (LES) of turbulent free shear flows and an application of a method to simulate the flow generated by a nozzle discharging into a stagnant reservoir. The objective of the study was to elucidate the complex features of the instantaneous flow field to help interpret the results of recent biological experiments in which live fish were exposed to the jet shear zone. The fish-jet experiments were conducted at the Pacific Northwest National Laboratory (PNNL) under the auspices of the U.S. Department of Energy’s Advanced Hydropower Turbine Systems program. The experiments were designed to establish critical thresholds of shear and turbulence-induced loads to guide the development of innovative, fish-friendly hydropower turbine designs.

  10. THE ROLE OF ERUPTING SIGMOID IN TRIGGERING A FLARE WITH PARALLEL AND LARGE-SCALE QUASI-CIRCULAR RIBBONS

    SciTech Connect

    Joshi, Navin Chandra; Magara, Tetsuya; Moon, Y.-J.; Liu, Chang; Wang, Haimin; Sun, Xudong E-mail: njoshi98@gmail.com

    2015-10-10

    In this paper, we present observations and analysis of an interesting sigmoid formation, eruption, and the associated flare that occurred on 2014 April 18 using multi-wavelength data sets. We discuss the possible role of the sigmoid eruption in triggering the flare, which consists of two different sets of ribbons: parallel ribbons and a large-scale quasi-circular ribbon. Several observational evidence and nonlinear force-free field extrapolation results show the existence of a large-scale fan-spine type magnetic configuration with a sigmoid lying under a section of the fan dome. The event can be explained with the following two phases. During the preflare phase, we observed the formation and appearance of the sigmoid via tether-cutting reconnection between the two sets of sheared fields under the fan dome. The second, main flare phase features the eruption of the sigmoid, the subsequent flare with parallel ribbons, and a quasi-circular ribbon. We propose the following multi-stage successive reconnection scenario for the main flare. First, tether-cutting reconnection is responsible for the formation and the eruption of the sigmoid structure. Second, the reconnection occurring in the wake of the erupting sigmoid produces the parallel flare ribbons on the both sides of the circular polarity inversion line. Third, the null-type reconnection higher in the corona, possibly triggered by the erupting sigmoid, leads to the formation of a large quasi-circular ribbon. For the first time, we suggest a mechanism for this type of flare consisting of a double set of ribbons triggered by an erupting sigmoid in a large-scale fan-spine-type magnetic configuration.

  11. Circularity measuring system: A shape gauge designed especially for use on large objects

    NASA Technical Reports Server (NTRS)

    Rohrkaste, G. R.

    1990-01-01

    The Circularity Measuring System (CMS) was developed to make an in-situ determination of shape similarity for selected fit large cylinders (RSRM segments). It does this to a repeatable accuracy of 0.10 mm (0.004 inch). This is less that the goal of 0.07 mm (0.003 inch), but was determined adequate because of the addition of an assembly aid that increased the entry chamfer of the clevis side of the joint. The usefulness of the CMS is demonstrated by the application to measurements other than its specified design purpose, such as submarine hull circularity, SRM mid-case circularity, as well as circularity of interfacing SRM tooling, specifically the rounding devices and horizontal disassembly devices. Commercialization of the tool is being pursued, since it is an enhancement of metrology technology for circularity determination. The most accurate in-situ technology it replaces is determined from a template. The CMS is an improvement in accuracy and operation.

  12. Circularity measuring system: A shape gauge designed especially for use on large objects

    NASA Astrophysics Data System (ADS)

    Rohrkaste, G. R.

    1990-04-01

    The Circularity Measuring System (CMS) was developed to make an in-situ determination of shape similarity for selected fit large cylinders (RSRM segments). It does this to a repeatable accuracy of 0.10 mm (0.004 inch). This is less that the goal of 0.07 mm (0.003 inch), but was determined adequate because of the addition of an assembly aid that increased the entry chamfer of the clevis side of the joint. The usefulness of the CMS is demonstrated by the application to measurements other than its specified design purpose, such as submarine hull circularity, SRM mid-case circularity, as well as circularity of interfacing SRM tooling, specifically the rounding devices and horizontal disassembly devices. Commercialization of the tool is being pursued, since it is an enhancement of metrology technology for circularity determination. The most accurate in-situ technology it replaces is determined from a template. The CMS is an improvement in accuracy and operation.

  13. A circular cylinder undergoing large-amplitude transverse oscillations in a slow uniform cross flow

    NASA Astrophysics Data System (ADS)

    Lam, K. M.; Liu, P.

    2013-05-01

    This study explores the vortex patterns formed by a circular cylinder undergoing lateral cylinder oscillations with large amplitudes and in the presence of a slow uniform cross flow. It is an extension of our previous study (Lam et al., 2010b) in which formation of the 2S, 2P and P+S vortex modes were discussed from the viewpoint of interaction of a uniform cross-flow with the vortex street patterns of a cylinder oscillating in an otherwise quiescent fluid at Keulegan-Carpenter numbers up to KC=8.9. The present paper reports three additional experimental sets in which the amplitudes of cylinder oscillations have even larger values, at A/D>2.5, and lie beyond the vortex mode map usually quoted from Williamson and Roshko (1988). It is found that the slow uniform cross-flow at λ/D≈3 and Reynolds number based on cross-flow velocity at 232 acts to convect the corresponding vortex patterns in the absence of cross-flow downstream across the line of cylinder oscillation. Vortex-vortex interaction and vortex-cylinder interaction are observed to affect the subsequent development of vortices. The P+S vortex mode is found to occur up to KC=16. At KC between 16 and 24, a new vortex mode is observed in which only one vortex pair can be convected downstream every cylinder oscillation cycle. Another new vortex mode with two vortex pairs and two stationary vortices are found at KC>24.

  14. Evidence of 3-D Reconnection at Null Point from the Observations of Circular Flares and Homologous Jets

    NASA Astrophysics Data System (ADS)

    Wang, Haimin; Liu, C.

    2012-05-01

    In recent studies by Pariat, Antiochos and DeVore (2009, 2010), fan-separatrix topology and magnetic reconnection at the null-point were simulated and found to produce homologous jets. This motivates us to search for axisymmetric magnetic structure and associated flaring/jetting activity. Using high-resolution ( 0.15" per pixel) and high-cadence ( 15 s) H-alpha center/offband observations obtained from the recently digitized films of Big Bear Solar Observatory, we were able to identify five large circular flares with associated surges. All the events exhibit a central parasite magnetic field surrounded by opposite polarity, forming a circular polarity inversion line (PIL). Consequently, a compact flare kernel at the center is surrounded by a circular ribbon, and together with the upward ejecting dark surge, these seem to depict a dome-like magnetic structure. Very interestingly, (1) the circular ribbon brightens sequentially rather than simultaneously, (2) the central compact flare kernel shows obvious motion, and (3) a remote elongated, co-temporal flare ribbon at a region with the same polarity as the central parasite site is seen in the series of four homologous events on 1991 March 17 and 18. The remote ribbon is 120" away from the jet location. Moreover, magnetic reconnection across the circular PIL is evident from the magnetic flux cancellation. These rarely observed homologous surges with circular as well as central and remote flare ribbons provide valuable evidence concerning the dynamics of magnetic reconnection in a null-point topology. This study is dedicated to Professor Hal Zirin, the founder of Big Bear Solar Observatory, who passed away on January 3, 2012.

  15. Observations of broad-band circular polarization in sunspots - Magnetic field correspondence

    NASA Technical Reports Server (NTRS)

    Illing, R. M. E.; Landman, D. A.; Mickey, D. L.

    1974-01-01

    The present work proposes a general rule relating the polarity of broad-band (spectral range: 5250 A to 5350 A) circular polarization fields observed in sunspots to that of the corresponding magnetic fields. The rule is illustrated with observations of particular spots.

  16. Wall-resolved large-eddy simulation of flow past a circular cylinder

    NASA Astrophysics Data System (ADS)

    Cheng, W.; Pullin, D. I.; Samtaney, R.

    2016-11-01

    Wall-resolved large-eddy simulations (LES) about a smooth-walled circular cylinder are described over a range of Reynolds number from ReD = 3 . 9 ×103 (subcritical) to above the drag crisis, ReD = 8 . 5 ×105 (supercritical), where D is the cylinder diameter. The span-wise domain is 3 D for ReD <=105 and D otherwise. The numerical method is a fourth-order finite-difference discretization on a standard curvilinear O-grid. The stretched-vortex sub-grid scale model is used in the whole domain, including regions of large-scale separated flow. For ReD <=105 , calculations of the skin-friction coefficient versus polar angle θ along the cylinder surface and its dependence on ReD are well captured in comparison with experimental data. Proper separation behavior is observed. For high ReD , a fine mesh 8192 × 1024 × 256 is used. It is found that a blowing/suction-type perturbation of the wall-normal velocity along a span-wise strip, with angular position at θ = 50 -60o , is then required in order to produce flow separation in accordance with experiment at Reynolds numbers in the drag-crisis regime. Results presented will focus on the skin-friction behavior and details of flow separation. Supported partially by KAUST OCRF Award No. URF/1/1394-01 and partially by NSF award CBET 1235605. The Cray XC40, Shaheen, at KAUST was utilized for all simulations.

  17. Few-mode and large-mode-area fiber with circularly distributed cores

    NASA Astrophysics Data System (ADS)

    Jin, Wenxing; Ren, Guobin; Jiang, Youchao; Wu, Yue; Xu, Yao; Yang, Yuguang; Shen, Ya; Ren, Wenhua; Jian, Shuisheng

    2017-03-01

    In this paper, a novel few-mode large-mode-area fiber is proposed. This type of fiber consists of 11 conventional cores and 8 air-hole cores circularly arranged around the center core. Few-mode condition equal to strict dual-mode here is available by appropriate adjusting on corepitch, relative refractive index difference and core radius. Large effective area of fundamental mode around 1403.561 μm2 could be achieved by optimization of structural parameters. Bending loss less than 10-3 dB / m is realized when effective area is over 1400 μm2.

  18. Large-Scale periodic solar velocities: An observational study

    NASA Technical Reports Server (NTRS)

    Dittmer, P. H.

    1977-01-01

    Observations of large-scale solar velocities were made using the mean field telescope and Babcock magnetograph of the Stanford Solar Observatory. Observations were made in the magnetically insensitive ion line at 5124 A, with light from the center (limb) of the disk right (left) circularly polarized, so that the magnetograph measures the difference in wavelength between center and limb. Computer calculations are made of the wavelength difference produced by global pulsations for spherical harmonics up to second order and of the signal produced by displacing the solar image relative to polarizing optics or diffraction grating.

  19. Experimental study of noise emitted by circular cylinders with large roughness

    NASA Astrophysics Data System (ADS)

    Alomar, Antoni; Angland, David; Zhang, Xin; Molin, Nicolas

    2014-12-01

    The aerodynamic noise generated by high Reynolds number flow around a bluff body with large surface roughness was investigated. This is a relevant problem in many applications, in particular aircraft landing gear noise. A circular cylinder in cross-flow and a zero-pressure-gradient turbulent boundary layer with various types of roughness was tested in a series of wind tunnel experiments. It has been shown that distributed roughness covering a circular cylinder affects the spectra over the entire frequency range. Roughness noise is dominant at high frequencies, and the peak frequency is well described by Howe's roughness noise model when scaled with the maximum outer velocity. There are differences between hemispherical and cylindrical roughness elements for both the circular cylinder and the zero-pressure-gradient turbulent boundary layer cases, indicating a dependence on roughness shape, not described by the considered roughness noise models. Cylindrical roughness generates higher noise levels at the highest frequencies, especially for the zero-pressure-gradient turbulent boundary layer case. Cable-type roughness aligned with the mean flow does not generate roughness noise, and its spectrum has been found to collapse with the smooth cylinder at medium and high frequencies. At low and medium frequencies the noise spectra have the same features as the smooth cylinder, but with higher shedding peak levels and fall-off levels, despite the decrease in spanwise correlation length. Roughness induces early separation, and thus a shift of the spectra to lower frequencies.

  20. Intensity-dependent circular polarization and circumstellar magnetic fields from the observation of SiO masers

    NASA Technical Reports Server (NTRS)

    Nedoluha, Gerald E.; Watson, William D.

    1994-01-01

    A new aspect of the propagation of astrophysical maser radiation in the presence of a magnetic field is described in which circular polarization is created. The resulting antisymmetric spectral line profile for this circular polarization resembles that produced by the ordinary Zeeman effect when the Zeeman splittings are much less than the spectral line breadth. It is caused by the change, with increasing maser intensity, in the axis of symmetry for the molecular quantum states from a direction that is parallel to the magnetic field to a direction that is parallel to the direction of propagation. When the maser is radiatively saturated, and the rate for stimulated emission is within an order of magnitude of the Zeeman splitting in frequency units, this 'intensity-dependent circular polarization' is greater than that due to the ordinary Zeeman effect by factors as large as 1000. The circular polarization that is observed in the spectra of circumstellar SiO (J = 1-0) masers associated with late-type giants and supergiants may then be caused by magnetic fields as weak as about 10 mG. With the standard Zeeman interpretation of the observations, magnetic fields of 10-100 G are indicated. The lower fields are similar to the limits obtained from the observation of the 22 GHz water masers which are typically somewhat further from the central star. The observed tendency for the fractional linear polarization of SiO masers to increase with increasing angular momentum of the molecular state is shown to be a likely result of anisotropic pumping. Errors are identified that invalidate a recent conflicting claim in the literature about the basic theory of maser polarization in the regime that is relevant here.

  1. Unprecedented large inverted repeats at the replication terminus of circular bacterial chromosomes suggest a novel mode of chromosome rescue

    PubMed Central

    El Kafsi, Hela; Loux, Valentin; Mariadassou, Mahendra; Blin, Camille; Chiapello, Hélène; Abraham, Anne-Laure; Maguin, Emmanuelle; van de Guchte, Maarten

    2017-01-01

    The first Lactobacillus delbrueckii ssp. bulgaricus genome sequence revealed the presence of a very large inverted repeat (IR), a DNA sequence arrangement which thus far seemed inconceivable in a non-manipulated circular bacterial chromosome, at the replication terminus. This intriguing observation prompted us to investigate if similar IRs could be found in other bacteria. IRs with sizes varying from 38 to 76 kbp were found at the replication terminus of all 5 L. delbrueckii ssp. bulgaricus chromosomes analysed, but in none of 1373 other chromosomes. They represent the first naturally occurring very large IRs detected in circular bacterial genomes. A comparison of the L. bulgaricus replication terminus regions and the corresponding regions without IR in 5 L. delbrueckii ssp. lactis genomes leads us to propose a model for the formation and evolution of the IRs. The DNA sequence data are consistent with a novel model of chromosome rescue after premature replication termination or irreversible chromosome damage near the replication terminus, involving mechanisms analogous to those proposed in the formation of very large IRs in human cancer cells. We postulate that the L. delbrueckii ssp. bulgaricus-specific IRs in different strains derive from a single ancestral IR of at least 93 kbp. PMID:28281695

  2. Unprecedented large inverted repeats at the replication terminus of circular bacterial chromosomes suggest a novel mode of chromosome rescue.

    PubMed

    El Kafsi, Hela; Loux, Valentin; Mariadassou, Mahendra; Blin, Camille; Chiapello, Hélène; Abraham, Anne-Laure; Maguin, Emmanuelle; van de Guchte, Maarten

    2017-03-10

    The first Lactobacillus delbrueckii ssp. bulgaricus genome sequence revealed the presence of a very large inverted repeat (IR), a DNA sequence arrangement which thus far seemed inconceivable in a non-manipulated circular bacterial chromosome, at the replication terminus. This intriguing observation prompted us to investigate if similar IRs could be found in other bacteria. IRs with sizes varying from 38 to 76 kbp were found at the replication terminus of all 5 L. delbrueckii ssp. bulgaricus chromosomes analysed, but in none of 1373 other chromosomes. They represent the first naturally occurring very large IRs detected in circular bacterial genomes. A comparison of the L. bulgaricus replication terminus regions and the corresponding regions without IR in 5 L. delbrueckii ssp. lactis genomes leads us to propose a model for the formation and evolution of the IRs. The DNA sequence data are consistent with a novel model of chromosome rescue after premature replication termination or irreversible chromosome damage near the replication terminus, involving mechanisms analogous to those proposed in the formation of very large IRs in human cancer cells. We postulate that the L. delbrueckii ssp. bulgaricus-specific IRs in different strains derive from a single ancestral IR of at least 93 kbp.

  3. Vibrational circular dichroism spectra for large molecules and molecules with heavy elements.

    PubMed

    Reiter, Kevin; Kühn, Michael; Weigend, Florian

    2017-02-07

    We present an implementation of vibrational circular dichroism (VCD) spectra in TURBOMOLE. We mainly followed the route proposed by Cheeseman [Chem. Phys. Lett. 252, 211 (1996)] and extended the modules for calculating the magnetic response and vibrational frequencies accordingly. The implementation allows for gauge origin invariant employment of effective core potentials, as demonstrated for Co(ppy)3, ppy = 2-Phenylpyridine. In this way, scalar relativistic effects are covered and heavy elements can be treated. Further, with the present implementation molecular symmetry may be efficiently exploited, which makes the calculation of large (symmetric) systems feasible. The calculation of the VCD spectrum of icosahedral C620(2+) is shown as an illustrative application.

  4. Vibrational circular dichroism spectra for large molecules and molecules with heavy elements

    NASA Astrophysics Data System (ADS)

    Reiter, Kevin; Kühn, Michael; Weigend, Florian

    2017-02-01

    We present an implementation of vibrational circular dichroism (VCD) spectra in TURBOMOLE. We mainly followed the route proposed by Cheeseman [Chem. Phys. Lett. 252, 211 (1996)] and extended the modules for calculating the magnetic response and vibrational frequencies accordingly. The implementation allows for gauge origin invariant employment of effective core potentials, as demonstrated for Co(ppy)3, ppy = 2-Phenylpyridine. In this way, scalar relativistic effects are covered and heavy elements can be treated. Further, with the present implementation molecular symmetry may be efficiently exploited, which makes the calculation of large (symmetric) systems feasible. The calculation of the VCD spectrum of icosahedral C6202+ is shown as an illustrative application.

  5. A comparison of shell theories for large-amplitude vibrations of circular cylindrical shells: Lagrangian approach

    NASA Astrophysics Data System (ADS)

    Amabili, M.

    2003-07-01

    Large-amplitude (geometrically non-linear) vibrations of circular cylindrical shells subjected to radial harmonic excitation in the spectral neighbourhood of the lowest resonances are investigated. The Lagrange equations of motion are obtained by an energy approach, retaining damping through Rayleigh's dissipation function. Four different non-linear thin shell theories, namely Donnell's, Sanders-Koiter, Flügge-Lur'e-Byrne and Novozhilov's theories, which neglect rotary inertia and shear deformation, are used to calculate the elastic strain energy. The formulation is also valid for orthotropic and symmetric cross-ply laminated composite shells. The large-amplitude response of perfect and imperfect, simply supported circular cylindrical shells to harmonic excitation in the spectral neighbourhood of the lowest natural frequency is computed for all these shell theories. Numerical responses obtained by using these four non-linear shell theories are also compared to results obtained by using the Donnell's non-linear shallow-shell equation of motion. A validation of calculations by comparison with experimental results is also performed. Both empty and fluid-filled shells are investigated by using a potential fluid model. The effects of radial pressure and axial load are also studied. Boundary conditions for simply supported shells are exactly satisfied. Different expansions involving from 14 to 48 generalized co-ordinates, associated with natural modes of simply supported shells, are used. The non-linear equations of motion are studied by using a code based on an arclength continuation method allowing bifurcation analysis.

  6. Circular depressions on 67P/Churyumov-Gerasimenko observed by the OSIRIS instrument

    NASA Astrophysics Data System (ADS)

    Besse, S. B.; Guilbert-Lepoutre, A.; Vincent, J.-B.; Bodewits, D.; Pajola, M.

    2015-10-01

    Since it close encounter with comet 67P/Churyumov- Gerasimenko (67P) in August 2014, the OSIRIS instrument [1] on-board the Rosetta Spacecraft has imaged the surface of the nucleus with unprecedented resolution. From its global morphology description, numerous circular depressions of different sizes and shapes have been observed [2, 3]. Few of these circular depressions, also called pits, have shown sign of activity with the detection of faint jet-like features originated most likely from their walls [4]. The mechanism responsible for the formation of these morphological features is not yet well understood, although different hypotheses have been raised such as the collapse of a ceiling above internal voids [4]. These voids could either be due to primordial structure of the comet's interior, or they could have been created with subsequentevolution of the nucleus. In both case, these features provide important constrains on the formation and evolution of cometary nucleus. Follow-up observations of the OSIRIS instrument should both confirm the nature of the activity (i.e., sporadic vs. regular) and the number of active depressions. In this analysis, we provide a thorough identificationand description of the circular depressions on the surface of the comet nucleus. These circular depressions exhibit different shapes, from pits to alcoves, with sizes varying from tens to hundred of meters, and ultimately with different texture on their walls (i.e., with fractures and polygons, or not). The accumulation of boulders at the bottom of some of these depressions indicates that whatever is creating these features, they are changing and evolving significantly trough time. These variations may reflect different formation mechanisms, or/and time of formation and evolution, and also probably internal heterogeneities below the comet's surface.

  7. Observation of an exceptional point in a two-dimensional ultrasonic cavity of concentric circular shells

    NASA Astrophysics Data System (ADS)

    Shin, Younghoon; Kwak, Hojeong; Moon, Songky; Lee, Sang-Bum; Yang, Juhee; An, Kyungwon

    2016-12-01

    We report observation of an exceptional point in circular shell ultrasonic cavities in both theory and experiment. In our theoretical analysis we first observe two interacting mode groups, fluid- and solid-based modes, in the acoustic cavities and then show the existence of an EP of these mode groups exhibiting a branch-point topological structure of eigenfrequencies around the EP. We then confirm the mode patterns as well as eigenfrequency structure around the EP in experiments employing the schlieren method, thereby demonstrating utility of ultrasound cavities as experimental platform for investigating non-Hermitian physics.

  8. Observation of an exceptional point in a two-dimensional ultrasonic cavity of concentric circular shells

    PubMed Central

    Shin, Younghoon; Kwak, Hojeong; Moon, Songky; Lee, Sang-Bum; Yang, Juhee; An, Kyungwon

    2016-01-01

    We report observation of an exceptional point in circular shell ultrasonic cavities in both theory and experiment. In our theoretical analysis we first observe two interacting mode groups, fluid- and solid-based modes, in the acoustic cavities and then show the existence of an EP of these mode groups exhibiting a branch-point topological structure of eigenfrequencies around the EP. We then confirm the mode patterns as well as eigenfrequency structure around the EP in experiments employing the schlieren method, thereby demonstrating utility of ultrasound cavities as experimental platform for investigating non-Hermitian physics. PMID:27958315

  9. Post Main Sequence Orbital Circularization of Binary Stars in the Large and Small Magellanic Clouds.

    SciTech Connect

    Faccioli, L; Alcock, C; Cook, K

    2007-11-20

    We present results from a study of the orbits of eclipsing binary stars (EBs) in the Magellanic Clouds. The samples comprise 4510 EBs found in the Large Magellanic Cloud (LMC) by the MACHO project, 2474 LMC EBs found by the OGLE-II project (of which 1182 are also in the MACHO sample), 1380 in the Small Magellanic Cloud (SMC) found by the MACHO project, and 1317 SMC EBs found by the OGLE-II project (of which 677 are also in the MACHO sample); we also consider the EROS sample of 79 EBs in the bar of the LMC. Statistics of the phase differences between primary and secondary minima allow us to infer the statistics of orbital eccentricities within these samples. We confirm the well-known absence of eccentric orbit in close binary stars. We also find evidence for rapid circularization in longer period systems when one member evolves beyond the main sequence, as also found by previous studies.

  10. Capacity of the circular plate condenser: analytical solutions for large gaps between the plates

    NASA Astrophysics Data System (ADS)

    Rao, T. V.

    2005-11-01

    A solution of Love's integral equation (Love E R 1949 Q. J. Mech. Appl. Math. 2 428), which forms the basis for the analysis of the electrostatic field due to two equal circular co-axial parallel conducting plates, is considered for the case when the ratio, τ, of distance of separation to radius of the plates is greater than 2. The kernel of the integral equation is expanded into an infinite series in odd powers of 1/τ and an approximate kernel accurate to {\\cal O}(\\tau^{-(2N+1)}) is deduced therefrom by terminating the series after an arbitrary but finite number of terms, N. The approximate kernel is rearranged into a degenerate form and the integral equation with this kernel is reduced to a system of N linear equations. An explicit analytical solution is obtained for N = 4 and the resulting analytical expression for the capacity of the circular plate condenser is shown to be accurate to {\\cal O}(\\tau^{-9}) . Analytical expressions of lower orders of accuracy with respect to 1/τ are deduced from the four-term (i.e., N = 4) solution and predictions (of capacity) from the expressions of different orders of accuracy (with respect to 1/τ) are compared with very accurate numerical solutions obtained by solving the linear system for large enough N. It is shown that the {\\cal O}(\\tau^{-9}) approximation predicts the capacity extremely well for any τ >= 2 and an {\\cal O}(\\tau^{-3}) approximation gives, for all practical purposes, results of adequate accuracy for τ >= 4. It is further shown that an approximate solution, applicable for the case of large distances of separation between the plates, due to Sneddon (Sneddon I N 1966 Mixed Boundary Value Problems in Potential Theory (Amsterdam: North-Holland) pp 230-46) is accurate to {\\cal O}(\\tau^{-6}) for τ >= 2.

  11. Electromagnetic Response of a Large Circular Loop Source on a Layered Earth: A New Computation Method

    NASA Astrophysics Data System (ADS)

    Singh, Nagendra Pratap; Mogi, Toru

    2005-01-01

    Integral expressions of electromagnetic (EM) field components due to a large circular loop source carrying an alternating (ac) current and placed on or above the surface of a layered earth model are transformed to such suitable forms that facilitate numerical computation of field response in quasi-static as well as non-quasi-static regions. The improper integrals occurring in expressions of EM field components are evaluated by converting these integrals into the convergent integrals using the process of subtraction or addition of an integral expression inside the integral sign and subsequently adjusting it or its equivalent analytic expression outside the integral sign. The adjusted integral expressions, in turn, are evaluated using the functional relationships described in this paper. The computation method based on this formulation takes into consideration the effects of both conduction as well as displacement currents, and is well suitable for any position of the source loop either in the air or on the surface of the model, in contrary to the earlier methods which face convergence problem. Moreover, the formulation is equally efficient for computing the EM response at any arbitrary receiver position either inside or outside the source loop. For illustrating the accuracy and applicability of the method and studying the nature of EM response of a loop source over a layered earth model, we have applied it for the computation of amplitude and phase of Hz field over the various 2-layer and 3-layer models. Results show their characteristic variations, and depict good resolution for the subsurface layering. The results are in agreement with those of the published results for the quasi-static region, and are new extension of quasi-static variation in the non-quasi-static region. The agreement of computed results with published results demonstrates the accuracy of the method. Moreover, this is the initial presentation of numerical results for an arbitrary in-loop point

  12. Survey of large circular and octagonal tanks operated at Norwegian commercial smolt and post-smolt sites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A survey was conducted to determine the geometry, operating parameters, and other key features of large circular or octagonal culture tanks used to produce Atlantic salmon smolt and post-smolt at six major Norwegian Atlantic salmon production companies. A total of 55 large tanks were reported at sev...

  13. The α-β circular scanning with large range and low noise.

    PubMed

    Liu, J; You, X; Wang, Y; Gu, K; Liu, C; Tan, J

    2017-03-15

    A circular-route scanning method called α-β circular scanning is proposed and realized using sinusoidal signals with a constant phase difference of π/2. Experiments show that the circular scanning range of α-β circular scanning is 57% greater than the rectangular scanning range of raster scanning within an effective optical field of view. Moreover, the scanning speed is improved by 7.8% over raster scanning because the whole sine signal is utilized in α-β circular scanning whereas the flyback area of the saw-tooth signal needs to be discarded in raster scanning. The maximum scanning acceleration decreases by a factor of 44, drastically decreasing the high noise, which should considerably elongate the lifetime of the galvanometers while inhibiting internal vibration. The proposed α-β circular scanning technique could be used in scanning imaging, optical tweezers and laser-beam fabrication.

  14. Fabrication of a microarray using a combination of the large circular sense and antisense DNA.

    PubMed

    Doh, Kyung-Oh; Lee, Yun-Han; Han, Kil-Hwan; Uhm, Seok-Yong; Kim, Jong-Pil; Bae, Yun-Ui; Park, Jeong-Hoh; Moon, Ik-Jae; Park, Jong-Gu

    2010-01-01

    In the present study, single-stranded large circular (LC)-sense molecules were utilized as probes for DNA microarrays and showed stronger binding signals than those of PCR-amplified cDNA probes. A microarray experiment using 284 LC-sense DNA probes found 6 upregulated and 7 downregulated genes in A549 cells as compared to WI38VA13 cells. Repeated experiments showed largely consistent results, and microarray data strongly correlated with data acquired from quantitative real-time RT-PCR. A large array comprising 5,079 LC-sense DNA was prepared, and analysis of the mean differential expression from dye-swap experiments revealed 332 upregulated and 509 downregulated genes in A549 cells compared to WI38VA13 cells. Subsequent functional analysis using an LC-antisense library of overexpressed genes identified 28 genes involved in A549 cell growth. These experiments demonstrated the proper features of LC-sense molecules as probe DNA for microarray and the potential utility of the combination of LC-sense and -antisense libraries for an effective functional validation of genes.

  15. An experimental approach to measure particle deposition in large circular ventilation ducts.

    PubMed

    Da, Guillaume; Géhin, Evelyne; Ben-Othmane, Mourad; Havet, Michel; Solliec, Camille; Motzkus, Charles

    2015-04-01

    The topic of this study is related to airborne particle dynamics in indoor environments. Lab-scale experiments have been performed to investigate particle deposition velocity to six different surfaces orientations (with respect to gravity) for fully developed turbulent flow in horizontal large circular ventilation ducts. Monodispersed aerosol particles (1-6 μm) were used in the deposition experiments. A very low particle mass (40 ng) was measured reliably above background level on duct surfaces by a means of a nondestructive stencil technique associated with fluorescence analysis. For 2-6 μm particles (diffusion and impaction regime), deposition rates to floors were much greater than rates to the ceiling and greater than rates to the wall. For 1-μm particles, the effect of surface orientation to particle deposition was not significant. Results were compared to the very few similar and published studies. This work was conducted in the frame of the CleanAirNet project which aimed at producing new knowledge, models, and techniques to help controlling the safety food stuffs, through a better control of aerosol particle (bioaerosols) transport and deposition in the ventilation networks of the food industry.

  16. Sidewall-box airlift pump provides large flows for aeration, CO2 stripping, and water rotation in large dual-drain circular tanks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conventional gas transfer technologies for aquaculture systems occupy a large amount of space, require a considerable capital investment, and can contribute to high electricity demand. In addition, diffused aeration in a circular culture tank can interfere with the hydrodynamics of water rotation a...

  17. Circular High-Q Resonating Isotropic Strain Sensors with Large Shift of Resonance Frequency under Stress

    PubMed Central

    Melik, Rohat; Unal, Emre; Perkgoz, Nihan Kosku; Puttlitz, Christian; Demir, Hilmi Volkan

    2009-01-01

    We present circular architecture bioimplant strain sensors that facilitate a strong resonance frequency shift with mechanical deformation. The clinical application area of these sensors is for in vivo assessment of bone fractures. Using a rectangular geometry, we obtain a resonance shift of 330 MHz for a single device and 170 MHz for its triplet configuration (with three side-by-side resonators on chip) under an applied load of 3,920 N. Using the same device parameters with a circular isotropic architecture, we achieve a resonance frequency shift of 500 MHz for the single device and 260 MHz for its triplet configuration, demonstrating substantially increased sensitivity. PMID:22303132

  18. A Highly Circularly Polarized Solar Radio Emission Component Observed at Hectometric Wavelengths

    NASA Astrophysics Data System (ADS)

    Reiner, M. J.; Kaiser, M. L.; Fainberg, J.; Bougeret, J.-L.

    2006-04-01

    We report here the observation of a rare solar radio event at hectometric wavelengths that was characterized by essentially 100% circularly polarized radiation and that was observed continuously for about six days, from May 17 to 23, 2002. This was the first time that a solar source with significantly polarized radiation was detected by the WAVES experiment on the Wind spacecraft. From May 19 to 22, the intense polarized radio emissions were characterized by quasi-periodic intensity variations with periods from one to two hours and with superposed drifting, narrowband, fine structures. The bandwidth of this radiation extended from about 400 kHz to 7 MHz, and the peak frequency of the frequency spectrum slowly decreased from 2 MHz to about 0.8 MHz over the course of four days. The radio source, at each frequency, was observed to slowly drift from east to west about the Sun, as viewed from the Earth and was estimated to lie between 26 and 82 R ⊙ ( R ⊙ = 696 000 km). We speculate that this unusual event may represent an interplanetary manifestation of a moving type IV burst and discuss possible radio emission mechanisms. The ISEE-3 spacecraft may possibly have detected a similar event some 26 years ago.

  19. Theory and experiments for large-amplitude vibrations of empty and fluid-filled circular cylindrical shells with imperfections

    NASA Astrophysics Data System (ADS)

    Amabili, M.

    2003-05-01

    The large-amplitude response of perfect and imperfect, simply supported circular cylindrical shells to harmonic excitation in the spectral neighbourhood of some of the lowest natural frequencies is investigated. Donnell's non-linear shallow-shell theory is used and the solution is obtained by the Galerkin method. Several expansions involving 16 or more natural modes of the shell are used. The boundary conditions on the radial displacement and the continuity of circumferential displacement are exactly satisfied. The effect of internal quiescent, incompressible and inviscid fluid is investigated. The non-linear equations of motion are studied by using a code based on the arclength continuation method. A series of accurate experiments on forced vibrations of an empty and water-filled stainless-steel shell have been performed. Several modes have been intensively investigated for different vibration amplitudes. A closed loop control of the force excitation has been used. The actual geometry of the test shell has been measured and the geometric imperfections have been introduced in the theoretical model. Several interesting non-linear phenomena have been experimentally observed and numerically reproduced, such as softening-type non-linearity, different types of travelling wave response in the proximity of resonances, interaction among modes with different numbers of circumferential waves and amplitude-modulated response. For all the modes investigated, the theoretical and experimental results are in strong agreement.

  20. ELF Sferics Observed at Large Distances

    NASA Astrophysics Data System (ADS)

    Dupree, N. A.; Moore, R. C.

    2012-12-01

    Model predictions of the ELF radio atmospheric generated by rocket-triggered lightning are compared with observations performed at at large (>1 Mm) distances. The ability to infer source characteristics using observations at great distances may prove to greatly enhance the understanding of lightning processes that are associated with the production of transient luminous events (TLEs) as well as other ionospheric effects associated with lightning. The modeling of the sferic waveform is carried out using a modified version of the Long Wavelength Propagation Capability (LWPC) code developed by the Naval Ocean Systems Center over a period of many years. LWPC is an inherently narrowband propagation code that has been modified to predict the broadband response of the Earth-ionosphere waveguide to an impulsive lightning flash while preserving the ability of LWPC to account for an inhomogeneous waveguide. ELF observations performed in Alaska and Antarctica during rocket-triggered lightning experiments at the International Center for Lightning Research and Testing (ICLRT) located at Camp Blanding, Florida are presented. The lightning current waveforms directly measured at the base of the lightning channel (at the ICLRT) are used together with LWPC to predict the sferic waveform observed at the receiver locations under various ionospheric conditions. This paper critically compares observations with model predictions.

  1. Amplicon structure in multidrug-resistant murine cells: a nonrearranged region of genomic DNA corresponding to large circular DNA.

    PubMed Central

    Ståhl, F; Wettergren, Y; Levan, G

    1992-01-01

    Multidrug resistance (MDR) in tumor cell lines is frequently correlated with amplification of one or more mdr genes. Usually the amplified domain also includes several neighboring genes. Using pulsed-field gel electrophoresis, we have established a restriction map covering approximately 2,200 kb in the drug-sensitive mouse tumor cell line TC13K. The mapped region is located on mouse chromosome 5 and includes the three mdr genes, the gene for the calcium-binding sorcin protein, and a gene with unknown function designated class 5. Long-range maps of the amplified DNA sequences in five of six MDR sublines that had been independently derived from TC13K generally displayed the same pattern as did the parental cell line. All six MDR sublines exhibited numerous double minutes, and one of them displayed a homogeneously staining region in a subpopulation. Large circular molecules, most likely identical to one chromatid of the double minutes, were detected in four of the sublines by linearization with gamma irradiation. The size of the circles was about 2,500 kb, which correlated to a single unit of the amplified domain. We therefore propose that in four independent instances of MDR development, a single unit of about 2,500 kb has been amplified in the form of circular DNA molecules. The restriction enzyme map of the amplified unit is unchanged compared with that of the parental cell line, whereas the joining sites of the circular DNA molecules are not identical but are in the same region. Images PMID:1545798

  2. Crowder/grader units improve harvest efficiency in large circular tanks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of larger and deeper tanks can reduce building, labor and other aquaculture production costs. However, the ability to grade and transfer large numbers of fish is more challenging when using large tanks. At The Conservation Fund Freshwater Institute, the authors have developed and evaluated i...

  3. Transcriptome-wide identification and functional investigation of circular RNA in the teleost large yellow croaker (Larimichthys crocea).

    PubMed

    Xu, Shuangbin; Xiao, Shijun; Qiu, Changliang; Wang, Zhiyong

    2017-04-01

    Circular RNA (circRNA) was first reported over thirty years ago. With the development of high-throughput sequencing technologies, circRNA has been identified in an increasing number of species. However, few studies on circRNA have been reported in teleost fish. Accumulating transcriptome and phenotype data enable us to probe the biological functions of circRNA in fish species. Here, we report the identification of circRNAs from RNA sequencing (RNA-seq) data in large yellow croaker (Larimichthys crocea), a commercially important marine fish in China and East Asia. Using the computational identification, 975 circular RNAs were detected, of which three were validated by experiments. GO and KEGG analyses revealed the biological functions of genes hosting the circRNAs were enriched in the progression of translation initiation, macromolecule metabolism and binding. Notably, we found that many circRNAs in large yellow croaker had abundant microRNA-binding sites. A total of 363 the identified circRNAs had more than five miRNA-binding sites, among which twenty-two had more than ten binding sites for the miRNA-430 and the let-7 family. Our study confirmed the presence of circRNAs in large yellow croaker for the first time, providing a valuable reference for circRNA identification in fish species. Meanwhile, this work confirmed that the RNA-seq data from the traditional linear transcriptome library could be used for preliminary circRNA identification, which may offer an important reference for preliminary circRNA investigations in other species.

  4. Launch window analysis of satellites in high eccentricity or large circular orbits

    NASA Technical Reports Server (NTRS)

    Renard, M. L.; Bhate, S. K.; Sridharan, R.

    1973-01-01

    Numerical methods and computer programs for studying the stability and evolution of orbits of large eccentricity are presented. Methods for determining launch windows and target dates are developed. Mathematical models are prepared to analyze the characteristics of specific missions.

  5. Large-eddy simulation of circular cylinder flow at subcritical Reynolds number: Turbulent wake and sound radiation

    NASA Astrophysics Data System (ADS)

    Guo, Li; Zhang, Xing; He, Guowei

    2016-02-01

    The flows past a circular cylinder at Reynolds number 3900 are simulated using large-eddy simulation (LES) and the far-field sound is calculated from the LES results. A low dissipation energy-conserving finite volume scheme is used to discretize the incompressible Navier-Stokes equations. The dynamic global coefficient version of the Vreman's subgrid scale (SGS) model is used to compute the sub-grid stresses. Curle's integral of Lighthill's acoustic analogy is used to extract the sound radiated from the cylinder. The profiles of mean velocity and turbulent fluctuations obtained are consistent with the previous experimental and computational results. The sound radiation at far field exhibits the characteristic of a dipole and directivity. The sound spectra display the -5/3 power law. It is shown that Vreman's SGS model in company with dynamic procedure is suitable for LES of turbulence generated noise.

  6. Large deflection of clamped circular plate and accuracy of its approximate analytical solutions

    NASA Astrophysics Data System (ADS)

    Zhang, Yin

    2016-02-01

    A different set of governing equations on the large deflection of plates are derived by the principle of virtual work (PVW), which also leads to a different set of boundary conditions. Boundary conditions play an important role in determining the computation accuracy of the large deflection of plates. Our boundary conditions are shown to be more appropriate by analyzing their difference with the previous ones. The accuracy of approximate analytical solutions is important to the bulge/blister tests and the application of various sensors with the plate structure. Different approximate analytical solutions are presented and their accuracies are evaluated by comparing them with the numerical results. The error sources are also analyzed. A new approximate analytical solution is proposed and shown to have a better approximation. The approximate analytical solution offers a much simpler and more direct framework to study the plate-membrane transition behavior of deflection as compared with the previous approaches of complex numerical integration.

  7. Method and Apparatus for Precisely Applying Large Planar Equi-Biaxial Strains to a Circular Membrane

    DTIC Science & Technology

    2013-04-01

    discussions, and for his attention to detail and quality in the manufacture of components using a laser cutter, Objet 3-D printer , lathe, and Haas CNC...package, VIC- 3D (from CorrelatedSolutions), was used to process the images and measure the resulting strain field. A representative sample of the...Love, A. E. H. A Treatise on the Mathematical Theory of Elasticity ; Cambridge University Press: New York, 1927. Rivlin, R. S.; Saunders, D. W. Large

  8. Moon-based Earth Observation for Large Scale Geoscience Phenomena

    NASA Astrophysics Data System (ADS)

    Guo, Huadong; Liu, Guang; Ding, Yixing

    2016-07-01

    The capability of Earth observation for large-global-scale natural phenomena needs to be improved and new observing platform are expected. We have studied the concept of Moon as an Earth observation in these years. Comparing with manmade satellite platform, Moon-based Earth observation can obtain multi-spherical, full-band, active and passive information,which is of following advantages: large observation range, variable view angle, long-term continuous observation, extra-long life cycle, with the characteristics of longevity ,consistency, integrity, stability and uniqueness. Moon-based Earth observation is suitable for monitoring the large scale geoscience phenomena including large scale atmosphere change, large scale ocean change,large scale land surface dynamic change,solid earth dynamic change,etc. For the purpose of establishing a Moon-based Earth observation platform, we already have a plan to study the five aspects as follows: mechanism and models of moon-based observing earth sciences macroscopic phenomena; sensors' parameters optimization and methods of moon-based Earth observation; site selection and environment of moon-based Earth observation; Moon-based Earth observation platform; and Moon-based Earth observation fundamental scientific framework.

  9. Circular Coinduction

    NASA Technical Reports Server (NTRS)

    Rosu, Grigore; Goguen, Joseph; Norvig, Peter (Technical Monitor)

    2001-01-01

    Circular coinduction is a technique for behavioral reasoning that extends cobasis coinduction to specifications with circularities. Because behavioral satisfaction is not recursively enumerable, no algorithm can work for every behavioral statement. However. algorithms using circular coinduction can prove every practical behavioral result that we know. This paper proves the correctness of circular coinduction and some consequences.

  10. Simulation optimization of filament parameters for uniform depositions of diamond films on surfaces of ultra-large circular holes

    NASA Astrophysics Data System (ADS)

    Wang, Xinchang; Shen, Xiaotian; Sun, Fanghong; Shen, Bin

    2016-12-01

    Chemical vapor deposition (CVD) diamond films have been widely applied as protective coatings on varieties of anti-frictional and wear-resistant components, owing to their excellent mechanical and tribological properties close to the natural diamond. In applications of some components, the inner hole surface will serve as the working surface that suffers severe frictional or erosive wear. It is difficult to realize uniform depositions of diamond films on surfaces of inner holes, especially ultra-large inner holes. Adopting a SiC compact die with an aperture of V80 mm as an example, a novel filament arrangement with a certain number of filaments evenly distributed on a circle is designed, and specific effects of filament parameters, including the filament number, arrangement direction, filament temperature, filament diameter, circumradius and the downward translation, on the substrate temperature distribution are studied by computational fluid dynamics (CFD) simulations based on the finite volume method (FVM), adopting a modified computational model well consistent with the actual deposition environment. Corresponding temperature measurement experiments are also conducted to verify the rationality of the computational model. From the aspect of depositing uniform boron-doped micro-crystalline, undoped micro-crystalline and undoped fine-grained composite diamond (BDM-UMC-UFGCD) film on such the inner hole surface, filament parameters as mentioned above are accurately optimized and compensated by orthogonal simulations. Moreover, deposition experiments adopting compensated optimized parameters and some typical contrastive parameters are also accomplished for further verifying the rationality of the computational model and the correctness of the compensation coefficient 0.7 defined for the downward translation determined by simulations. More importantly, on the basis of more simulations and verification tests, a general filament arrangement model suitable for V50-120 mm

  11. Toroidal circular dichroism

    NASA Astrophysics Data System (ADS)

    Raybould, T. A.; Fedotov, V. A.; Papasimakis, N.; Kuprov, I.; Youngs, I. J.; Chen, W. T.; Tsai, D. P.; Zheludev, N. I.

    2016-07-01

    We demonstrate that the induced toroidal dipole, represented by currents flowing on the surface of a torus, makes a distinct and indispensable contribution to circular dichroism. We show that toroidal circular dichroism supplements the well-known mechanism involving electric dipole and magnetic dipole transitions. We illustrate this with rigorous analysis of the experimentally measured polarization-sensitive transmission spectra of an artificial metamaterial, constructed from elements of toroidal symmetry. We argue that toroidal circular dichroism will be found in large biomolecules with elements of toroidal symmetry and should be taken into account in the interpretation of circular dichroism spectra of organics.

  12. The use of a circular external skeletal fixation device for the management of long bone osteotomies in large ruminants: an experimental study.

    PubMed

    Aithal, H P; Singh, G R; Hoque, M; Maiti, S K; Kinjavdekar, P; Pawde, A M; Setia, H C

    2004-08-01

    The study was undertaken to evaluate the feasibility of a simple, inexpensive model of circular external fixator (CEF) for use in large ruminants. A simple model of CEF frames consisting of four full rings (13-19 cm diameter, 4 cm wide and 4 mm thick with 18-24 holes) connected by threaded rods (8 mm diameter, 10-15 cm long) and nuts was developed using mild (low carbon) steel and were nickel-plated. In the first phase of the study, three male cow calves were utilized to study the feasibility of application of the fixators in the metatarsus, tibia and radius, in reference of adaptation and tolerance by animals. In the second phase, the fixators were tested in osteotomized bones. Six bull calves of 1.5-2 years of age weighing about 200-250 kg were utilized for this purpose. After preparing the area for aseptic surgery, under xylazine (at 0.1 mg/kg, i.m.)-ketamine (i.v. till effect) general anaesthesia, the test bone (metatarsus, radius and tibia in two animals each) was approached through the medial surface and an osteotomy was created with a saw and chisel at the mid-diaphysis. The pre-constructed 4-ring CEF was mounted on the limb around the test bone in such a way that it formed a cylinder with the axis of the limb at the centre. Each ring was then fixed to the bone with a pair of beaded wires (316 SS) of 3.5 mm diameter. During the post-operative period, the animals were observed for any change in behaviour, tolerance of the fixators, the weight bearing on the test limb, the status of the fixator, and the level of reduction of the osteotomy, alignment and healing at different intervals. The fixation of CEF was easier in the metatarsus and radius than in the tibia. The inner ring diameters found adequate for metatarsus, radius and tibia were 13-15 cm, 15-17 cm and 17-19 cm, respectively. The fixators applied to different bones were well-tolerated, and the animals could lay down, stand and walk freely with the fixator without any problems. All the animals showed

  13. Non-Linear Dynamics and Stability of Circular Cylindrical Shells Containing Flowing Fluid. Part Iv: Large-Amplitude Vibrations with Flow

    NASA Astrophysics Data System (ADS)

    AMABILI, M.; PELLICANO, F.; PAÏDOUSSIS, M. P.

    2000-11-01

    The response of a shell conveying fluid to harmonic excitation, in the spectral neighbourhood of one of the lowest natural frequencies, is investigated for different flow velocities. The theoretical model has already been presented in Part I of the present study. Non-linearities due to moderately large-amplitude shell motion are considered by using Donnell's non-linear shallow-shell theory. Linear potential flow theory is applied to describe the fluid-structure interaction by using the model proposed by Paı̈doussis and Denise. For different amplitudes and frequencies of the excitation and for different flow velocities, the following are investigated numerically: (1) periodic response of the system; (2) unsteady and stochastic motion; (3) loss of stability by jumps to bifurcated branches. The effect of the flow velocity on the non-linear periodic response of the system has also been investigated. Poincaré maps and bifurcation diagrams are used to study the unsteady and stochastic dynamics of the system. Amplitude modulated motions, multi-periodic solutions, chaotic responses, cascades of bifurcations as the route to chaos and the so-called “blue sky catastrophe” phenomenon have all been observed for different values of the system parameters; the latter two have been predicted here probably for the first time for the dynamics of circular cylindrical shells.

  14. Large-amplitude, circularly polarized, compressive, obliquely propagating electromagnetic proton cyclotron waves throughout the Earth's magnetosheath: low plasma β conditions

    SciTech Connect

    Remya, B.; Reddy, R. V.; Lakhina, G. S.; Tsurutani, B. T.; Falkowski, B. J.; Echer, E.; Glassmeier, K.-H.

    2014-09-20

    During 1999 August 18, both Cassini and WIND were in the Earth's magnetosheath and detected transverse electromagnetic waves instead of the more typical mirror-mode emissions. The Cassini wave amplitudes were as large as ∼14 nT (peak to peak) in a ∼55 nT ambient magnetic field B {sub 0}. A new method of analysis is applied to study these waves. The general wave characteristics found were as follows. They were left-hand polarized and had frequencies in the spacecraft frame (f {sub scf}) below the proton cyclotron frequency (f{sub p} ). Waves that were either right-hand polarized or had f {sub scf} > f{sub p} are shown to be consistent with Doppler-shifted left-hand waves with frequencies in the plasma frame f{sub pf} < f{sub p} . Thus, almost all waves studied are consistent with their being electromagnetic proton cyclotron waves. Most of the waves (∼55%) were found to be propagating along B {sub 0} (θ{sub kB{sub 0}}<30{sup ∘}), as expected from theory. However, a significant fraction of the waves were found to be propagating oblique to B {sub 0}. These waves were also circularly polarized. This feature and the compressive ([B {sub max} – B {sub min}]/B {sub max}, where B {sub max} and B {sub min} are the maximum and minimum field magnitudes) nature (ranging from 0.27 to 1.0) of the waves are noted but not well understood at this time. The proton cyclotron waves were shown to be quasi-coherent, theoretically allowing for rapid pitch-angle transport of resonant protons. Because Cassini traversed the entire subsolar magnetosheath and WIND was in the dusk-side flank of the magnetosheath, it is surmised that the entire region was filled with these waves. In agreement with past theory, it was the exceptionally low plasma β (0.35) that led to the dominance of the proton cyclotron wave generation during this interval. A high-speed solar wind stream ((V{sub sw} ) = 598 km s{sup –1}) was the source of this low-β plasma.

  15. Circular codes, symmetries and transformations.

    PubMed

    Fimmel, Elena; Giannerini, Simone; Gonzalez, Diego Luis; Strüngmann, Lutz

    2015-06-01

    Circular codes, putative remnants of primeval comma-free codes, have gained considerable attention in the last years. In fact they represent a second kind of genetic code potentially involved in detecting and maintaining the normal reading frame in protein coding sequences. The discovering of an universal code across species suggested many theoretical and experimental questions. However, there is a key aspect that relates circular codes to symmetries and transformations that remains to a large extent unexplored. In this article we aim at addressing the issue by studying the symmetries and transformations that connect different circular codes. The main result is that the class of 216 C3 maximal self-complementary codes can be partitioned into 27 equivalence classes defined by a particular set of transformations. We show that such transformations can be put in a group theoretic framework with an intuitive geometric interpretation. More general mathematical results about symmetry transformations which are valid for any kind of circular codes are also presented. Our results pave the way to the study of the biological consequences of the mathematical structure behind circular codes and contribute to shed light on the evolutionary steps that led to the observed symmetries of present codes.

  16. Evolutionary outcomes for pairs of planets undergoing orbital migration and circularization: second-order resonances and observed period ratios in Kepler's planetary systems

    NASA Astrophysics Data System (ADS)

    Xiang-Gruess, M.; Papaloizou, J. C. B.

    2015-05-01

    In order to study the origin of the architectures of low-mass planetary systems, we perform numerical surveys of the evolution of pairs of coplanar planets in the mass range (1-4) M⊕. These evolve for up to 2 × 107 yr under a range of orbital migration torques and circularization rates assumed to arise through interaction with a protoplanetary disc. Near the inner disc boundary, significant variations of viscosity, interaction with density waves or with the stellar magnetic field could occur and halt migration, but allow circularization to continue. This was modelled by modifying the migration and circularization rates. Runs terminated without an extended period of circularization in the absence of migration torques gave rise to either a collision, or a system close to a resonance. These were mostly first order with a few per cent terminating in second-order resonances. Both planetary eccentricities were small <0.1 and all resonant angles liberated. This type of survey produced only a limited range of period ratios and cannot reproduce Kepler observations. When circularization alone operates in the final stages, divergent migration occurs causing period ratios to increase. Depending on its strength the whole period ratio range between 1 and 2 can be obtained. A few systems close to second-order commensurabilities also occur. In contrast to when arising through convergent migration, resonant trapping does not occur and resonant angles circulate. Thus, the behaviour of the resonant angles may indicate the form of migration that led to near resonance.

  17. Long gradient mode and large-scale structure observables

    NASA Astrophysics Data System (ADS)

    Allahyari, Alireza; Firouzjaee, Javad T.

    2017-03-01

    We extend the study of long-mode perturbations to other large-scale observables such as cosmic rulers, galaxy-number counts, and halo bias. The long mode is a pure gradient mode that is still outside an observer's horizon. We insist that gradient-mode effects on observables vanish. It is also crucial that the expressions for observables are relativistic. This allows us to show that the effects of a gradient mode on the large-scale observables vanish identically in a relativistic framework. To study the potential modulation effect of the gradient mode on halo bias, we derive a consistency condition to the first order in gradient expansion. We find that the matter variance at a fixed physical scale is not modulated by the long gradient mode perturbations when the consistency condition holds. This shows that the contribution of long gradient modes to bias vanishes in this framework.

  18. Large deployable reflectors for telecom and earth observation applications

    NASA Astrophysics Data System (ADS)

    Scialino, L.; Ihle, A.; Migliorelli, M.; Gatti, N.; Datashvili, L.; van `t Klooster, K.; Santiago Prowald, J.

    2013-12-01

    Large deployable antennas are one of the key components for advanced missions in the fields of telecom and earth observation. In the recent past, missions have taken on board large deployable reflector (LDR) up to 22 m of diameter and several missions have already planned embarking large reflectors, such as the 12 m of INMARSAT XL or BIOMASS. At the moment, no European LDR providers are available and the market is dominated by Northrop-Grumman and Harris. Consequently, the development of European large reflector technology is considered a key step to maintain commercial and strategic competitiveness (ESA Large Reflector Antenna Working Group Final Report, TEC-EEA/2010.595/CM, 2010). In this scenario, the ESA General Study Project RESTEO (REflector Synergy between Telecom and Earth Observation), starting from the identification of future missions needs, has identified the most promising reflector concepts based on European heritage/technology, able to cover the largest range of potential future missions for both telecom and earth observation. This paper summarizes the activities and findings of the RESTEO Study.

  19. Solar Observations with the Atacama Large Millimeter/submillimeter Array

    NASA Astrophysics Data System (ADS)

    Wedemeyer, Sven

    2015-08-01

    The interferometric Atacama Large Millimeter/submillimeter Array (ALMA) has already demonstrated its impressive capabilities by observing a large variety of targets ranging from protoplanetary disks to galactic nuclei. ALMA is also capable of observing the Sun and has been used for five solar test campaigns so far. The technically challenging solar observing modes are currently under development and regular observations are expected to begin in late 2016.ALMA consists of 66 antennas located in the Chilean Andes at an altitude of 5000 m and is a true leap forward in terms of spatial resolution at millimeter wavelengths. The resolution of reconstructed interferometric images of the Sun is anticipated to be close to what current optical solar telescopes can achieve. In combination with the high temporal and spectral resolution, these new capabilities open up new parameter spaces for solar millimeter observations.The solar radiation at wavelengths observed by ALMA originates from the chromosphere, where the height of the sampled layer increases with selected wavelength. The continuum intensity is linearly correlated to the local gas temperature in the probed layer, which makes ALMA essentially a linear thermometer. During flares, ALMA can detect additional non-thermal emission contributions. Measurements of the polarization state facilitate the valuable determination of the chromospheric magnetic field. In addition, spectrally resolved observations of radio recombination and molecular lines may yield great diagnostic potential, which has yet to be investigated and developed.Many different scientific applications for a large range of targets from quiet Sun to active regions and prominences are possible, ranging from ultra-high cadence wave studies to flare observations. ALMA, in particular in combination with other ground-based and space-borne instruments, will certainly lead to fascinating new findings, which will advance our understanding of the atmosphere of our Sun

  20. Quantum tunneling observed without its characteristic large kinetic isotope effects

    PubMed Central

    Hama, Tetsuya; Ueta, Hirokazu; Kouchi, Akira; Watanabe, Naoki

    2015-01-01

    Classical transition-state theory is fundamental to describing chemical kinetics; however, quantum tunneling is also important in explaining the unexpectedly large reaction efficiencies observed in many chemical systems. Tunneling is often indicated by anomalously large kinetic isotope effects (KIEs), because a particle’s ability to tunnel decreases significantly with its increasing mass. Here we experimentally demonstrate that cold hydrogen (H) and deuterium (D) atoms can add to solid benzene by tunneling; however, the observed H/D KIE was very small (1–1.5) despite the large intrinsic H/D KIE of tunneling (≳100). This strong reduction is due to the chemical kinetics being controlled not by tunneling but by the surface diffusion of the H/D atoms, a process not greatly affected by the isotope type. Because tunneling need not be accompanied by a large KIE in surface and interfacial chemical systems, it might be overlooked in other systems such as aerosols or enzymes. Our results suggest that surface tunneling reactions on interstellar dust may contribute to the deuteration of interstellar aromatic and aliphatic hydrocarbons, which could represent a major source of the deuterium enrichment observed in carbonaceous meteorites and interplanetary dust particles. These findings could improve our understanding of interstellar physicochemical processes, including those during the formation of the solar system. PMID:26034285

  1. A star identification algorithm for large FOV observations

    NASA Astrophysics Data System (ADS)

    Duan, Yu; Niu, Zhaodong; Chen, Zengping

    2016-10-01

    Due to the broader extent of observation and higher detection probability of space targets, large FOV (field of vision) optical instruments are widely used in astronomical applications.. However, the high density of observed stars and the distortion of the optical system often bring about inaccuracy in star locations. So in large FOV observations, many conventional star identification algorithms do not show very good performance. In this paper, we propose a star identification method with a low requirement for observation accuracy and thus suitable for large FOV circumstances. The proposed method includes two stages. The former is based on the match group algorithm, in addition to which we exploit the information of differential angles of inclination for verification. The inclinations of satellite stars are computed by reference to the selected pole stars. Then we obtain a set of identified stars for further recognition. The latter stage involves four steps. First, we derive the relationship between the rectangular coordinates of catalog stars and sensor stars with the identified locations obtained. Second, we transform the sensor coordinates to the catalog coordinates and find the catalog stars at close range as candidates. Third, we calculate the angle of inclination of each unidentified sensor star in relation to the nearest previously identified one, and the angular separation between them as well, to compare with those of the candidates. At last, candidates satisfying the limitations are considered the appropriate correspondences. The experimental results show that in large FOV observations, the proposed method presents better performance in comparison with several typical star identification methods in open literature.

  2. Nucleon-nucleon scattering observables in large- Nc QCD

    NASA Astrophysics Data System (ADS)

    Cohen, Thomas D.; Gelman, Boris A.

    2002-08-01

    Nucleon-nucleon scattering observables are considered in the context of the large Nc limit of QCD for initial states with moderately high momenta ( p∼ Nc). The scattering is studied in the framework of the time-dependent mean-field approximation. We focus on the dependence of those observables on the spin and isospin of the initial state which may be computed using time-dependent mean-field theory. We show that, up to corrections, all such observables must be invariant under simultaneous spin and isospin flips (i.e., rotations through π/2 in both spin and isospin) acting on either particle. All observables of this class obtained from spin unpolarized measurements must be isospin independent up to 1/ Nc corrections. Moreover, it can be shown that the leading correction is of relative order 1/ Nc2 rather than 1/ Nc.

  3. Observation of large nematic domains of discotic liquid crystals

    NASA Astrophysics Data System (ADS)

    Shinde, Abhijeet; Wang, Xuezhen; Cheng, Zhengdong

    2015-03-01

    Discotic liquid crystals are commonly found in nature in the form of clay, nacre. They are technologically important in applications such as conductive polymers, semiconductors and photovoltaics. Size and its distribution play an important role in their self-assemblies. Here we observed large nematic domains of discotic liquid crystals grown on a time scale of months. The development of such domains is observed to be faster for nanodisks that relatively smaller in size. The orientation of nanodisks is affected by gravity and inter-particle interactions which are yet to be fully understood.

  4. Considerations for Observational Research using Large Datasets in Radiation Oncology

    PubMed Central

    Jagsi, Reshma; Bekelman, Justin E.; Chen, Aileen; Chen, Ronald C.; Hoffman, Karen; Shih, Ya-Chen Tina; Smith, Benjamin D.; Yu, James B.

    2014-01-01

    The radiation oncology community has witnessed growing interest in observational research conducted using large-scale data sources such as registries and claims-based datasets. With the growing emphasis on observational analyses in health care, the radiation oncology community must possess a sophisticated understanding of the methodological considerations of such studies in order to evaluate evidence appropriately to guide practice and policy. Because observational research has unique features that distinguish it from clinical trials and other forms of traditional radiation oncology research, the Red Journal assembled a panel of experts in health services research to provide a concise and well-referenced review, intended to be informative for the lay reader, as well as for scholars who wish to embark on such research without prior experience. This review begins by discussing the types of research questions relevant to radiation oncology that large-scale databases may help illuminate. It then describes major potential data sources for such endeavors, including information regarding access and insights regarding the strengths and limitations of each. Finally, it provides guidance regarding the analytic challenges that observational studies must confront, along with discussion of the techniques that have been developed to help minimize the impact of certain common analytical issues in observational analysis. Features characterizing a well-designed observational study include clearly defined research questions, careful selection of an appropriate data source, consultation with investigators with relevant methodological expertise, inclusion of sensitivity analyses, caution not to overinterpret small but significant differences, and recognition of limitations when trying to evaluate causality. This review concludes that carefully designed and executed studies using observational data that possess these qualities hold substantial promise for advancing our understanding of

  5. Mid-latitude lidar observations of large sporadic sodium layers

    SciTech Connect

    Senft, D.C.; Collins, R.L.; Gardner, C.S. )

    1989-07-01

    During the early morning of October 31, 1988 two large sporadic Na (Na{sub s}) layers were observed near the mesopause above Urbana, IL (40{degree}N, 88{degree}W) with a Na lidar system. The layers began forming near 102 km at 0026 LST and 0110 LST and moved downward with vertical velocities as high as 4 ms{sup {minus}1} before dissipating between 94 and 96 km. The duration of each layer was approximately 80 min. The layers were narrow ({approximately} 1 km FWHM) and dense with maximum densities approaching 7,800 cm{sup {minus}3}. The characteristics of these two Na{sub s} layers are very similar to those of similar phenomena observed recently at Andoya, Norway and Mauna Kea, Hawaii. Lidar observations of the mesospheric Na layer have been conducted routinely by several groups at mid-latitudes for almost 20 years. Although large Na{sub s} layers now appear to be relatively common at low- and high-latitudes, to our knowledge the two layers described in this letter are only the second observation of this puzzling phenomenon at mid-latitudes.

  6. Probing large-scale structure with radio observations

    NASA Astrophysics Data System (ADS)

    Brown, Shea D.

    This thesis focuses on detecting magnetized relativistic plasma in the intergalactic medium (IGM) of filamentary large-scale structure (LSS) by observing synchrotron emission emitted by structure formation shocks. Little is known about the IGM beyond the largest clusters of galaxies, and synchrotron emission holds enormous promise as a means of probing magnetic fields and relativistic particle populations in these low density regions. I'll first report on observations taken at the Very Large Array and the Westerbork Synthesis Radio Telescope of the diffuse radio source 0809+39. I use these observations to demonstrate that 0809+39 is likely the first "radio relic" discovered that is not associated with a rich |"X-ray emitting cluster of galaxies. I then demonstrate that an unconventional reprocessing of the NVSS polarization survey can reveal structures on scales from 15' to hundreds of degrees, far larger than the nominal shortest-baseline scale. This yields hundreds of new diffuse sources as well as the identification of a new nearby galactic loop . These observations also highlight the major obstacle that diffuse galactic foreground emission poses for any search for large-scale, low surface- brightness extragalactic emission. I therefore explore the cross-correlation of diffuse radio emission with optical tracers of LSS as a means of statistically detecting the presence of magnetic fields in the low-density regions of the cosmic web. This initial study with the Bonn 1.4 GHz radio survey yields an upper limit of 0.2 mG for large-scale filament magnetic fields. Finally, I report on new Green Bank Telescope and Westerbork Synthesis Radio Telescope observations of the famous Coma cluster of galaxies. Major findings include an extension to the Coma cluster radio relic source 1253+275 which makes its total extent ~2 Mpc, as well as a sharp edge, or "front", on the Western side of the radio halo which shows a strong correlation with merger activity associated with an

  7. Doppler lidar observations of plume dynamics from large wildfires

    NASA Astrophysics Data System (ADS)

    Lareau, N.; Clements, C. B.

    2014-12-01

    Novel Doppler lidar observations of smoke plumes from large wildfires are made from a mobile atmospheric profiling system. Few quantitative observations exist that resolve the plume dynamics of active wildfires. Our observations elucidate three important and poorly understood aspects of convective columns: (1) column rotation, (2) penetrative convection, and (3) deep pyrocumulus clouds. Our first observational case examines vigorus anti-cyclonic rotation that occurred in a rapidly developing wildfire. The convective column was first purely convergent, then as the fire intensified, the column acquired strong (+/- 15 m s-1) anticyclonic rotation. The Doppler lidar recorded the vortex structure, strength, and evolution, including the merger of smaller vorticies into a single long-lived vortex. The second case examines the interaction of the convective plumes with shear layers and capping stable layers. These data show explosive convective growth as fire-induced buoyancy penetrated into the free troposphere. Observations of entrainment into the plumes is expecitly resolved in the lidar scans. The final case examines rarely observed deep pyrocumulus clouds associated with an intense forest fire. The lidar data reveal plume structure, including t the height of the lifted condensation level and the full height of the plume top which was in excess of 8 km AGL.

  8. Revisiting the observed surface climate response to large volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Wunderlich, Fabian; Mitchell, Daniel M.

    2017-01-01

    In light of the range in presently available observational, reanalysis and model data, we revisit the surface climate response to large tropical volcanic eruptions from the end of the 19th century until present. We focus on the dynamically driven response of the North Atlantic Oscillation (NAO) and the radiative-driven tropical temperature response. Using 10 different reanalysis products and the Hadley Centre Sea Level Pressure observational dataset (HadSLP2) we confirm a positive tendency in the phase of the NAO during boreal winters following large volcanic eruptions, although we conclude that it is not as clear cut as the current literature suggests. While different reanalyses agree well on the sign of the surface volcanic NAO response for individual volcanoes, the spread in the response is often large (˜ 1/2 standard deviation). This inter-reanalysis spread is actually larger for the more recent volcanic eruptions, and in one case does not encompass observations (El Chichón). These are all in the satellite era and therefore assimilate more atmospheric data that may lead to a more complex interaction for the surface response. The phase of the NAO leads to a dynamically driven warm anomaly over northern Europe in winter, which is present in all datasets considered. The general cooling of the surface temperature due to reduced incoming shortwave radiation is therefore disturbed by dynamical impacts. In the tropics, where less dynamically driven influences are present, we confirm a predominant cooling after most but not all eruptions. All datasets agree well on the strength of the tropical response, with the observed and reanalysis response being statistically significant but the modelled response not being significant due to the high variability across models.

  9. Effect of circularly polarized femtosecond laser pulses on alignment dynamics of linear molecules observed by strong-field photoelectron yields

    NASA Astrophysics Data System (ADS)

    Kaya, Necati; Kaya, Gamze; Strohaber, James; Kolomenskii, Alexandre A.; Schuessler, Hans A.

    2016-10-01

    By measuring femtosecond laser driven strong-field electron yields for linear molecules aligned by circularly polarized femtosecond laser pulses, we study the rotational wavepacket evolution of N2, CO, and C2H2 gas molecules. We show that circular polarization produces a net alignment along the laser pulse propagation axis at certain phases of the evolution. This gives the possibility to control alignment of linear molecules outside the plane of polarization, which can provide new capabilities for molecular imaging. The experimental results were compared to the calculated field-free molecular alignment parameter taking into account the effects of electronic structure and symmetry of the molecules. By fitting the calculated impulsive alignment parameter to the measured experimental data we determined the molecular rotational constants of the linear gas molecules.

  10. Interferometric observations of large biologically interesting interstellar and cometary molecules

    PubMed Central

    Snyder, Lewis E.

    2006-01-01

    Interferometric observations of high-mass regions in interstellar molecular clouds have revealed hot molecular cores that have substantial column densities of large, partly hydrogen-saturated molecules. Many of these molecules are of interest to biology and thus are labeled “biomolecules.” Because the clouds containing these molecules provide the material for star formation, they may provide insight into presolar nebular chemistry, and the biomolecules may provide information about the potential of the associated interstellar chemistry for seeding newly formed planets with prebiotic organic chemistry. In this overview, events are outlined that led to the current interferometric array observations. Clues that connect this interstellar hot core chemistry to the solar system can be found in the cometary detection of methyl formate and the interferometric maps of cometary methanol. Major obstacles to understanding hot core chemistry remain because chemical models are not well developed and interferometric observations have not been very sensitive. Differentiation in the molecular isomers glycolaldehdye, methyl formate, and acetic acid has been observed, but not explained. The extended source structure for certain sugars, aldehydes, and alcohols may require nonthermal formation mechanisms such as shock heating of grains. Major advances in understanding the formation chemistry of hot core species can come from observations with the next generation of sensitive, high-resolution arrays. PMID:16894168

  11. Satellite observations of large power plants and megacities from GOSAT

    NASA Astrophysics Data System (ADS)

    Oda, Tom; Maksyutov, Shamil; Boesch, Hartmut; Butz, Andre; Ganshin, Alexander; Guerlet, Sandrine; Parker, Robert; O'Dell, Chris; Oshchepkov, Sergey; Yoshida, Yukio; Zhuravlev, Ruslan; Yokota, Tatsuya

    2013-04-01

    Fossil fuel CO2 emissions are a major source of CO2 to the global carbon cycle over decadal time scales and international efforts to curb those missions are required for mitigating climate change. Although emissions from nations are estimated and reported to help monitor their compliance of emission reductions, we still lack an objective method to monitor emissions directly. Future carbon-observing space missions are thus expected to provide an independent tool for directly measuring emissions. We proposed and have implemented satellite observations specifically over intense large point sources (LPS), including large fossil-fueled power plants and megacities, worldwide (N > 300) using the Japanese Greenhouse Gases Observing SATelllite (GOSAT). Our target LPS sites have been occasionally included in the observation schedule of GOSAT and the measurements are made using the target observation mode. This proposal was officially accepted by the GOSAT project office and we have attempted to use these data to detect signatures of man-made greenhouse gas emissions. We have submitted our locations of interest on a monthly basis two month prior to observation. We calculated the X_CO2 concentration enhancement due to the LPS emissions. We analyzed GOSAT X_CO2 retrievals from four research groups (five products total): the National Institute for Environmental Studies (NIES) (both the NIES standard Level 2 and NIES-PPDF products), the NASA Atmospheric CO2 from Space (ACOS) team (ACOS Level 2 product), the Netherlands Institute for Space Research (SRON)/Karlsruhe Institute of Technology, Germany (RemoTeC), and the University of Leicester, UK (Full-Physics CO2 retrieval dataset). Although we obtained fewer retrieved soundings relative to what we requested (probably due to geophysical difficulties in the retrievals), we did obtain statistically significant enhancements at some LPS sites where weather condition were ideal for viewing. We also implemented simulations of enhanced X

  12. Circular Motion.

    ERIC Educational Resources Information Center

    Lee, Paul D.

    1995-01-01

    Provides a period-long activity using battery powered cars rolling in a circular motion on a tile floor. Students measure the time and distance as the car moves to derive the equation for centripetal acceleration. (MVL)

  13. VLA (Very Large Array) observations of a solar-noise storm

    SciTech Connect

    Lang, K.R.; Willson, R.F.

    1986-01-01

    The first Very Large Array (VLA) observations of the sun at 92-cm wavelength (328 MHz) are presented. A solar-noise storm, which lasted at least 3 hours, was detected at this wavelength; it consisted of burst-like spikes superimposed on a slowly varying background, and both storm components were 95 + or - 5% right-hand circularly polarized. A long-duration soft-x-ray event preceded the radio radiation by 30 m, suggesting a disturbance moving outwards at a velocity of v = 78 km/s. The 92-cm noise storm was resolved with an angular resolution of 9 sec for time intervals as short as 13 s. During the onset and early phases, the storm consisted of four compact sources, each with an angular diameter of 40 sec, oriented within an elongated source with angular dimensions of 40 sec by 200 sec. During the subsequent hour, the most-intense emission was located in two 40-sec sources separated by 100 sec. Snapshot maps revealed a persistent elongated source at successive peaks, with a scatter in the source position. A systematic position shift of Deta Theta/sub I/ > or = 15 sec can be produced by the Earth's ionosphere, but these effects can be removed by frequent observations of a nearby calibrator source. The observations confirm previously reported trends for a decrease in source size at higher frequencies, but they suggest a hitherto unresolved complexity in source structure.

  14. Linking very short arcs from large database of asteroid observations

    NASA Astrophysics Data System (ADS)

    Gronchi, Giovanni Federico

    2015-08-01

    With the improvements of the observational technology for the new surveys the number of asteroid detections is rapidly increasing. For this reason we must use very efficient methods to compute orbits with these data. We have to identify observations taken in different nights as belonging to the same asteroid. If we do not have an efficient algorithm for that, the unidentifiedobservation database can increase without control, and we risk to detect the same objects multiple times without being able to realize it.If a short arc of asteroid observations is not enough to compute an orbit we usually can compute an 'attributable', i.e. a vector whose components are the topocentric angular position and velocity of the asteroid at the mean epoch of the observations. To define an orbit we only need to know the topocentric radial distance and velocity of the observed body at that epoch.Solving the linkage problem means to use the information encoded in two attributables to compute one or more preliminary orbits. Among the different ways to deal with this problem, we can use the first integrals of Kepler's motion to derive polynomial equations for this purpose.We present a recent achievement with this approach: we can derive a polynomial equation of degree 9 in the topocentric radial distance of the asteroid at the mean epoch of one of the two attributables.Note that the classical orbit determination method by Gauss, using three angular positions of the asteroid, employs a polynomial equation of degree 8.However, if N is the number of observations per night of a survey, we have to check O(N^2) pairs of data with the linkage method and O(N^3) triples with Gauss method.We also show the results of the application of this new method to a large database of asteroid detections.

  15. Testing coupled dark energy with large scale structure observation

    SciTech Connect

    Yang, Weiqiang; Xu, Lixin E-mail: lxxu@dlut.edu.cn

    2014-08-01

    The coupling between the dark components provides a new approach to mitigate the coincidence problem of cosmological standard model. In this paper, dark energy is treated as a fluid with a constant equation of state, whose coupling with dark matter is Q-bar =3Hξ{sub x}ρ-bar {sub x}. In the frame of dark energy, we derive the evolution equations for the density and velocity perturbations. According to the Markov Chain Monte Carlo method, we constrain the model by currently available cosmic observations which include cosmic microwave background radiation, baryon acoustic oscillation, type Ia supernovae, and fσ{sub 8}(z) data points from redshift-space distortion. The results show the interaction rate in σ regions: ξ{sub x} = 0.00328{sub -0.00328-0.00328-0.00328}{sup +0.000736+0.00549+0.00816}, which means that the recently cosmic observations favor a small interaction rate which is up to the order of 10{sup -2}, meanwhile, the measurement of redshift-space distortion could rule out the large interaction rate in the σ region.

  16. The Flux of Large Meteoroids Observed with Lunar Impact Monitoring

    NASA Technical Reports Server (NTRS)

    Cooke, W. J.; Suggs, R. M.; Moser, D. E.; Suggs, R. J.

    2014-01-01

    The flux of large meteoroids is not well determined due to relatively low number statistics, due mainly to the lack of collecting area available to meteor camera systems (10(2)-10(5) km2). Larger collecting areas are needed to provide reasonable statistics for flux calculations. The Moon, with millions of square kilometers of lunar surface, can be used as a detector for observing the population of large meteoroids in the tens of grams to kilogram mass range. This is accomplished by observing the flash of light produced when a meteoroid impacts the lunar surface, converting a portion of its kinetic energy to visible light detectable from Earth. A routine monitoring program at NASA's Marshall Space Flight Center has recorded over 300 impact flashes since early 2006. The program utilizes multiple 0.35 m (14 inch) Schmidt-Cassegrain telescopes, outfitted with video cameras using the 1/2 inch Sony EXview HAD CCDTM chip, to perform simultaneous observations of the earthshine hemisphere of the Moon when the lunar phase is between 0.1 and 0.5. This optical arrangement permits monitoring of approximately 3.8x10(6) km2 of lunar surface. A selection of 126 flashes recorded in 266.88 hours of photometric skies was analyzed, creating the largest and most homogeneous dataset of lunar impact flashes to date. Standard CCD photometric techniques outlined in [1] were applied to the video to determine the luminous energy, kinetic energy, and mass for each impactor, considering a range of luminous efficiencies. The flux to a limiting energy of 2.5x10(-6) kT TNT or 1.05×10(7) J is 1.03×10(-7) km(-2) hr(-1) and the flux to a limiting mass of 30 g is 6.14×10(-10) m(-2) yr(-1). Comparisons made with measurements and models of the meteoroid population indicate that the flux of objects in this size range is slightly lower (but within the error bars) than the power law distribution determined for the near Earth object population by [2].

  17. Large uncertainties in observed daily precipitation extremes over land

    NASA Astrophysics Data System (ADS)

    Herold, Nicholas; Behrangi, Ali; Alexander, Lisa V.

    2017-01-01

    We explore uncertainties in observed daily precipitation extremes over the terrestrial tropics and subtropics (50°S-50°N) based on five commonly used products: the Climate Hazards Group InfraRed Precipitation with Stations (CHIRPS) dataset, the Global Precipitation Climatology Centre-Full Data Daily (GPCC-FDD) dataset, the Tropical Rainfall Measuring Mission (TRMM) multi-satellite research product (T3B42 v7), the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record (PERSIANN-CDR), and the Global Precipitation Climatology Project's One-Degree Daily (GPCP-1DD) dataset. We use the precipitation indices R10mm and Rx1day, developed by the Expert Team on Climate Change Detection and Indices, to explore the behavior of "moderate" and "extreme" extremes, respectively. In order to assess the sensitivity of extreme precipitation to different grid sizes we perform our calculations on four common spatial resolutions (0.25° × 0.25°, 1° × 1°, 2.5° × 2.5°, and 3.75° × 2.5°). The impact of the chosen "order of operation" in calculating these indices is also determined. Our results show that moderate extremes are relatively insensitive to product and resolution choice, while extreme extremes can be very sensitive. For example, at 0.25° × 0.25° quasi-global mean Rx1day values vary from 37 mm in PERSIANN-CDR to 62 mm in T3B42. We find that the interproduct spread becomes prominent at resolutions of 1° × 1° and finer, thus establishing a minimum effective resolution at which observational products agree. Without improvements in interproduct spread, these exceedingly large observational uncertainties at high spatial resolution may limit the usefulness of model evaluations. As has been found previously, resolution sensitivity can be largely eliminated by applying an order of operation where indices are calculated prior to regridding. However, this approach is not appropriate when true area averages are desired

  18. The sources of super-high energetic electron at relativistic circularly-polarized laser-solid interactions in the presence of large scale pre-plasmas

    NASA Astrophysics Data System (ADS)

    Wu, D.; Krasheninnikov, S. I.; Luan, S. X.; Yu, W.

    2016-12-01

    The two stage electron acceleration model [Wu et al., Nucl. Fusion 57, 016007 (2017)] is extended to investigate the sources of super-hot electrons at intense circularly polarized (CP) laser solid interactions. It is found that in the presence of large scale pre-formed plasmas, super-high energetic electrons can be generated. For laser of intensity 1020 W /cm2 and pre-plasma of scale-length 10 μm , the cut-off energy of electrons by CP laser can be as high as 120 MeV compared with 100 MeV by linearly polarized laser. This unexpected acceleration can be also explained by the two-stage acceleration model. The envelop modulation of reflected CP laser is figured out, and a modified scaling law of the maximal-possible energy gain when including the modulation effect is obtained.

  19. Large anisotropic Fe orbital moments in perpendicularly magnetized Co2FeAl Heusler alloy thin films revealed by angular-dependent x-ray magnetic circular dichroism

    NASA Astrophysics Data System (ADS)

    Okabayashi, Jun; Sukegawa, Hiroaki; Wen, Zhenchao; Inomata, Koichiro; Mitani, Seiji

    2013-09-01

    Perpendicular magnetic anisotropy (PMA) in Heusler alloy Co2FeAl thin films sharing an interface with a MgO layer is investigated by angular-dependent x-ray magnetic circular dichroism. Orbital and spin magnetic moments are deduced separately for Fe and Co 3d electrons. In addition, the PMA energies are estimated using the orbital magnetic moments parallel and perpendicular to the film surfaces. We found that PMA in Co2FeAl is determined mainly by the contribution of Fe atoms with large orbital magnetic moments, which are enhanced at the interface between Co2FeAl and MgO. Furthermore, element specific magnetization curves of Fe and Co are found to be similar, suggesting the existence of ferromagnetic coupling between Fe and Co PMA directions.

  20. Determination of Boundary Layer Transition and Separation on Double Circular Arc Compressor Blades in a Large Subsonic Cascade.

    DTIC Science & Technology

    1983-09-01

    J* ,- - - r APPENDIX A: PLENUM MODIFICATION The plenum configuration described by Moebius [Ref. 4] ’-I introduced large scale unsteadiness into...Measuring Plane and in the Plenum Chamber of the Rectilinear Cascade, Master’s Thesis, Naval Postgraduate School, Monterey, California, 1966. 4. Moebius

  1. Experimental observation of very large magnetoconductance in microbial nanowires

    NASA Astrophysics Data System (ADS)

    Malvankar, Nikhil; Vargas, Madeline; Lovley, Derek; Tuominen, Mark

    2011-03-01

    Microbial nanowires are 2-5 nm-wide conductive proteinous pili filaments secreted by some bacteria, which can grow tens of micrometers long and may serve as a conduit for long-distance electron transport. Our previous studies demonstrated that pili of Geobacter sulfurreducens exhibit properties akin to disordered metals, and indicated a temperature-driven crossover from the regime of weak localization (WL) to strong localization (SL). Here we report a very large positive magnetoconductance (MC), up to 10,000 %, at 300K. MC increased exponentially with magnetic field. A crossover from positive MC (WL regime) to negative MC (SL) was observed at ~ 280 K when the localization and the phase-breaking lengths are expected to become comparable. We attribute positive MC to destruction of the quantum interference of delocalized electron wavefunctions and negative MC to shrinkage of the localized electron wavefunctions due to applied magnetic field, which is consistent with the temperature dependence of conductivity. Funded by U.S. DOE Genomic Sciences and Office of Naval Research.

  2. 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.

  3. Observations Regarding Small Eolian Dunes and Large Ripples on Mars

    NASA Technical Reports Server (NTRS)

    Edgett, Kenneth S.

    2001-01-01

    Eolian bedforms occur at the interface between a planetary surface and its atmosphere; they present a proxy record of the influence of climate, expressed in sediment transport, over that surface. High resolution images (1.5 - 12 m/pixel) from the Mars Global Surveyor (MGS) Mars Orbiter Camera provide glimpses of the most recent events shaping the martian landscape. Thousands of images exhibit small transverse dunes or large eolian ripples that have crest-to-crest spacings of 10 to 60 m, heights of a few to 10 m. Bedforms of the size and patterns seen in the Mars photographs are rarely described among Earth's eolian landforms; in terms of size and morphology, most of these fall between traditional definitions of "ripples" and "dunes". Dunes are composed chiefly of materials transported by saltation, ripples are smaller forms moved along by the impact of saltating grains (traction). The largest reported eolian ripples on Earth (granule ripples, megaripples) are typically smaller than the bedforms observed on Mars; likewise, most dunes are typically larger. The small dunes and large ripples on Mars come in a variety of relative albedos, despite an early MGS impression that they are all of high albedo. Some ripples occur on the surfaces of sand dunes; these are most likely true granule ripples. However, most of these bedforms occur in troughs, pits, craters, and on deflated plains. Despite impressions early in the MGS mission, they do not occur everywhere (e.g., they are rare on the northern plains) but they do occur at a range of elevations from the highest volcanoes to the deepest basins. Where they occur on a hard substrate among larger sand dunes, the big dunes have over-ridden the smaller bedforms, indicating that the smaller features are older and perhaps indurated or very coarse-grained. At other locales, the small bedforms have been mantled by material settled from suspension, in other cases they are being exhumed and may be lithified. Still other examples are

  4. Large breast compressions: Observations and evaluation of simulations

    SciTech Connect

    Tanner, Christine; White, Mark; Guarino, Salvatore; Hall-Craggs, Margaret A.; Douek, Michael; Hawkes, David J.

    2011-02-15

    Purpose: Several methods have been proposed to simulate large breast compressions such as those occurring during x-ray mammography. However, the evaluation of these methods against real data is rare. The aim of this study is to learn more about the deformation behavior of breasts and to assess a simulation method. Methods: Magnetic resonance (MR) images of 11 breasts before and after applying a relatively large in vivo compression in the medial direction were acquired. Nonrigid registration was employed to study the deformation behavior. Optimal material properties for finite element modeling were determined and their prediction performance was assessed. The realism of simulated compressions was evaluated by comparing the breast shapes on simulated and real mammograms. Results: Following image registration, 19 breast compressions from 8 women were studied. An anisotropic deformation behavior, with a reduced elongation in the anterior-posterior direction and an increased stretch in the inferior-superior direction was observed. Using finite element simulations, the performance of isotropic and transverse isotropic material models to predict the displacement of internal landmarks was compared. Isotropic materials reduced the mean displacement error of the landmarks from 23.3 to 4.7 mm, on average, after optimizing material properties with respect to breast surface alignment and image similarity. Statistically significantly smaller errors were achieved with transverse isotropic materials (4.1 mm, P=0.0045). Homogeneous material models performed substantially worse (transverse isotropic: 5.5 mm; isotropic: 6.7 mm). Of the parameters varied, the amount of anisotropy had the greatest influence on the results. Optimal material properties varied less when grouped by patient rather than by compression magnitude (mean: 0.72 vs 1.44). Employing these optimal materials for simulating mammograms from ten MR breast images of a different cohort resulted in more realistic breast

  5. Buttock Reconstruction in Sarcoma Surgery: An Esthetic Sigmoidplasty Closure for Large Circular Defects Using Double Opposing Skin Flaps

    PubMed Central

    Daya, Mahendra

    2016-01-01

    Background: Large defects arising from extirpation surgery of buttock sarcomas requiring adjuvant radiotherapy are best closed with flap surgery. The traditional solutions are derived from an approach to pressure sores, which were designed for the ischial, sacral, or trochanteric areas, and have now been adapted for true buttock defects. This invariably destroys the esthetics of the buttock. We describe a novel technique of sigmoidplasty, which preserves most of the esthetic features. Methods: We report on a retrospective review of 11 consecutive buttock sarcomas managed at our institution between 2009 and 2014, focusing on those for which the described reconstruction method was used (N = 5). Results: The immediate outcome was very good. In 1 patient, partial loss of 1 of the flaps and the management thereof resulted in a minor contour deformity. In general, the buttock volume was significantly decreased but the shape was preserved. This was obtained without secondary donor defect and with minimal contour irregularity. Long-term follow-up remained pleasing, and all patients were satisfied with the outcomes. Conclusions: The described technique of buttock defect closure satisfies the oncoplastic principles of tumor surgery with the added benefit of superior esthetics. We suggest that it is a versatile adjunct to the reconstructive surgeon’s armamentarium for buttock reconstruction after sarcoma excision, particularly when the gluteal artery perforator systems are unavailable. PMID:27826466

  6. Large Scale Surface Radiation Budget from Satellite Observation

    NASA Technical Reports Server (NTRS)

    Pinker, R. T.

    1995-01-01

    During the current reporting period, the focus of our work was on preparing and testing an improved version of our Surface Radiation Budget algorithm for processing the ISCCP D1 data routinely at the SRB Satellite Data Analysis Center (SDAC) at NASA Langley Research Center. The major issues addressed are related to gap filling and to testing whether observations made from ERBE could be used to improve current procedures of converting narrowband observations, as available from ISCCP, into broadband observations at the TOA. The criteria for selecting the optimal version are to be based on results of intercomparison with ground truth.

  7. Complex circular subsidence structures in tephra deposited on large blocks of ice: Varða tuff cone, Öræfajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Smellie, J. L.; Walker, A. J.; McGarvie, D. W.; Burgess, R.

    2016-08-01

    Several broadly circular structures up to 16 m in diameter, into which higher strata have sagged and locally collapsed, are present in a tephra outcrop on southwest Öræfajökull, southern Iceland. The tephra was sourced in a nearby basaltic tuff cone at Varða. The structures have not previously been described in tuff cones, and they probably formed by the melting out of large buried blocks of ice emplaced during a preceding jökulhlaup that may have been triggered by a subglacial eruption within the Öræfajökull ice cap. They are named ice-melt subsidence structures, and they are analogous to kettle holes that are commonly found in proglacial sandurs and some lahars sourced in ice-clad volcanoes. The internal structure is better exposed in the Varða examples because of an absence of fluvial infilling and reworking, and erosion of the outcrop to reveal the deeper geometry. The ice-melt subsidence structures at Varða are a proxy for buried ice. They are the only known evidence for a subglacial eruption and associated jökulhlaup that created the ice blocks. The recognition of such structures elsewhere will be useful in reconstructing more complete regional volcanic histories as well as for identifying ice-proximal settings during palaeoenvironmental investigations.

  8. SEARCH Workshop on Large-Scale Atmosphere/Cryosphere Observations

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The purpose of the workshop held in Seattle during 27-29 November 2001 was to review existing land, sea ice, and atmospheric observations and the prospect for an Arctic System Reanalysis, through white papers, invited speakers, and panels. A major task for SEARCH was to determine how existing observation systems can be best used and enhanced to understand and anticipate the course of the ongoing changes in the Arctic. The primary workshop conclusion is that there is no cohesion among various Arctic disciplines and data types to form a complete observation set of Arctic change; a second workshop conclusion is that present data sets are vastly underutilized in understanding Arctic change; a third conclusion is that a distributed observing system must accommodate a wide range of spatial patterns of variability.

  9. Very Large Array observations of Uranus at 2. 0 cm

    SciTech Connect

    Berge, G.L.; Muhleman, D.O.; Linfield, R.P.

    1988-07-01

    Radio observations of Uranus obtained at 2.0 cm with the B configuration of the VLA during April 1985 are reported. The calibration and data-reduction procedures are described in detail, and the results are presented in tables, maps, and graphs and compared with IRIS 44-micron observations (Hanel et al., 1986). Features discussed include highest brightness centered on the pole rather than on the subearth point, a decrease in brightness temperature (by up to 9 K) at latitudes between -20 and -50 deg (well correlated with the IRIS data), and disk-center position (corrected for the observed radio asymmetry) in good agreement with that found on the basis of the outer contours of the image. 15 references.

  10. MESSENGER Observations of Large Flux Transfer Events at Mercury

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Lepping, Ronald P.; Wu, Chin-Chun; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Boardsen, Scott A.; Killen, Rosemary M.; Korth, Haje; Krimigis, Stamatios M.; McClintock, William E.; McNutt, Ralph L., Jr.; Sarantos, Menelaos; Schriver, David; Solomon, Sean C.; Travnicek, Pavel; Zurbuchen, Thomas H.

    2010-01-01

    Six flux transfer events (FTEs) were encountered during MESSENGER's first two flybys of Mercury (M1 and M2). For M1 the interplanetary magnetic field (IMF) was predominantly northward and four FTEs with durations of 1 to 6 s were observed in the magnetosheath following southward IMF turnings. The IMF was steadily southward during M2, and an FTE 4 s in duration was observed just inside the dawn magnetopause followed approx. 32 s later by a 7 s FTE in the magnetosheath. Flux rope models were fit to the magnetic field data to determine FTE dimensions and flux content. The largest FTE observed by MESSENGER had a diameter of approx. 1 R(sub M) (where R(sub M) is Mercury s radius), and its open magnetic field increased the fraction of the surface exposed to the solar wind by 10 - 20 percent and contributed up to approx. 30 kV to the cross-magnetospheric electric potential.

  11. MESSENGER Observations of Large Flux Transfer Events at Mercury

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Lepping, Ronald P.; Wu, Chin-Chun; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Boardsen, Scott A.; Killen, Rosemary M.; Korth, Haje; Krimigis, Stamatios M.; McClintock, William E.; McNutt, Ralph L., Jr.; Sarantos, Menelaos; Schriver, David; Solomon, Sean C.; Travnicek, Pavel; Zurbuchen, Thomas H.

    2010-01-01

    Six flux transfer events (FTEs) were encountered during MESSENGER's first two flybys of Mercury (MI and M2). For MI the interplanetary magnetic field (IMF) was predominantly northward and four FTEs with durations of 1 to 6 s were observed in the magnetosheath following southward 1M F turnings. The IMF was steadily southward during M2, and an FTE 4 s in duration was observed just inside the dawn magnetopause followed approx.32 s later by a 7-s FTE in the magnetosheath. Flux rope models were fit to the magnetic field data to detem11ne PTE dimensions and flux content The largest FTE observed by MESSENGER had a diameter of approx. 1 R(sub M) (where R(sub M) is Mercury's radius), and its open magnetic field increased the fraction of the surface exposed to the solar wind by 10 - 20 percent and contributed up to approx.30 kV to the cross-magnetospheric electric potential.

  12. OH Observations in the Direction of H2O Masers in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Gardner, F. F.; Whiteoak, J. B.

    1985-07-01

    1.6-GHz OH observations have been made towards five LMC H II regions that have been associated with H2O maser emission. Circularly polarized maser emission was observed in two cases, 0510-689 and 0540-696B, but not towards 0540-697A (N159), where emission had been previously reported. Weak OH absorption was detected for two regions (0539-691 and 0540-697A) and possibly a third (0540-696). The optical depths are low (around 0.01), providing additional evidence that molecular densities in the LMC are signficantly lower than in our Galaxy.

  13. Efficient inference of hidden Markov models from large observation sequences

    NASA Astrophysics Data System (ADS)

    Priest, Benjamin W.; Cybenko, George

    2016-05-01

    The hidden Markov model (HMM) is widely used to model time series data. However, the conventional Baum- Welch algorithm is known to perform poorly when applied to long observation sequences. The literature contains several alternatives that seek to improve the memory or time complexity of the algorithm. However, for an HMM with N states and an observation sequence of length T, these alternatives require at best O(N) space and O(N2T) time. Given the preponderance of applications that increasingly deal with massive amounts of data, an alternative whose time is O(T)+poly(N) is desired. Recent research presents an alternative to the Baum-Welch algorithm that relies on nonnegative matrix factorization. This document examines the space complexity of this alternative approach and proposes further optimizations using approaches adopted from the matrix sketching literature. The result is a streaming algorithm whose space complexity is constant and time complexity is linear with respect to the size of the observation sequence. The paper also presents a batch algorithm that allow for even further improved space complexity at the expense of an additional pass over the observation sequence.

  14. Sufficient observables for large-scale structure in galaxy surveys

    NASA Astrophysics Data System (ADS)

    Carron, J.; Szapudi, I.

    2014-03-01

    Beyond the linear regime, the power spectrum and higher order moments of the matter field no longer capture all cosmological information encoded in density fluctuations. While non-linear transforms have been proposed to extract this information lost to traditional methods, up to now, the way to generalize these techniques to discrete processes was unclear; ad hoc extensions had some success. We pointed out in Carron and Szapudi's paper that the logarithmic transform approximates extremely well the optimal `sufficient statistics', observables that extract all information from the (continuous) matter field. Building on these results, we generalize optimal transforms to discrete galaxy fields. We focus our calculations on the Poisson sampling of an underlying lognormal density field. We solve and test the one-point case in detail, and sketch out the sufficient observables for the multipoint case. Moreover, we present an accurate approximation to the sufficient observables in terms of the mean and spectrum of a non-linearly transformed field. We find that the corresponding optimal non-linear transformation is directly related to the maximum a posteriori Bayesian reconstruction of the underlying continuous field with a lognormal prior as put forward in the paper of Kitaura et al.. Thus, simple recipes for realizing the sufficient observables can be built on previously proposed algorithms that have been successfully implemented and tested in simulations.

  15. Cold Rydberg atoms in circular states

    NASA Astrophysics Data System (ADS)

    Anderson, David; Schwarzkopf, Andrew; Raithel, Georg

    2012-06-01

    Circular-state Rydberg atoms are interesting in that they exhibit a unique combination of extraordinary properties; long lifetimes (˜n^5), large magnetic moments (l=|m|=n-1) and no first order Stark shift. Circular states have found applications in cavity quantum electrodynamics and precision measurements [1,2], among other studies. In this work we present the production of circular states in an atom trapping apparatus using an adiabatic state-switching method (the crossed-field method [3]). To date, we have observed lifetimes of adiabatically prepared states of several milliseconds. Their relatively large ionization electric fields have been verified by time-of-flight signatures of ion trajectories. We intend to explore the magnetic trapping of circular state Rydberg atoms, as well as their production and interaction properties in ultra-cold and degenerate samples.[4pt] [1] P. Bertet et al., Phys. Rev. Lett., 88, 14 (2002)[0pt] [2] M. Brune et al., Phys. Rev. Lett., 72, 21 (1994)[0pt] [3] D. Delande and J.C. Gay, Europhys. Lett., 5, 303-308 (1988).

  16. Observation of EAS using a large water tank

    NASA Astrophysics Data System (ADS)

    Inoue, K.; Sakuyama, H.; Suzuki, N.; Suzuki, T.

    1985-08-01

    Using a large water tank (30 m in diameter, 4.5 m in depth) transition of extensive air showers (EAS) was investigated at Taro (200 m above sea level). There are set 150,0.4 sq m proportional counters on the bottom of the water tank. A conventional EAS array of 25 plastic scintillation detectors was arranged within several tens meter from the water tank. A proportional counter (10x10x200 cc x2) is made of a square shaped pipe of iron. Tungsten wire (100 mu m phi) is stretched tight in the center of the counter. A gas mixture of 90% argon and 10% methane is used at 760 mmHg. About 3000 EAS were obtained through 1 m of water since 1984.

  17. Observation of EAS using a large water tank

    NASA Technical Reports Server (NTRS)

    Inoue, K.; Sakuyama, H.; Suzuki, N.; Suzuki, T.

    1985-01-01

    Using a large water tank (30 m in diameter, 4.5 m in depth) transition of extensive air showers (EAS) was investigated at Taro (200 m above sea level). There are set 150,0.4 sq m proportional counters on the bottom of the water tank. A conventional EAS array of 25 plastic scintillation detectors was arranged within several tens meter from the water tank. A proportional counter (10x10x200 cc x2) is made of a square shaped pipe of iron. Tungsten wire (100 mu m phi) is stretched tight in the center of the counter. A gas mixture of 90% argon and 10% methane is used at 760 mmHg. About 3000 EAS were obtained through 1 m of water since 1984.

  18. Observation of DCO^+^ in the Large Magellanic Cloud.

    NASA Astrophysics Data System (ADS)

    Heikkilä, A.; Johansson, L. E. B.; Olofsson, H.

    1997-03-01

    We report on the detection of DCO^+^ and, tentatively, DCN in their rotational J=2-1 transitions towards the N159 region in the Large Magellanic Cloud (LMC). These detections of deuterated molecules in an extragalactic source complement those already published by Chin et al. (1996). The resulting estimate of the HCO^+^/DCO^+^ abundance ratio is 120_-60_^+60^ (total 2σ uncertainties). Assuming a Galactic D/H ratio for the LMC leads to an estimate of the kinetic temperature of the molecular gas and an upper limit to the fractional electron abundance of 10-27K and a few x10^-5^, respectively. The temperature estimate is in accordance with excitation calculations using a number of other molecules. The HCO^+^/DCO^+^ abundance ratio in N159 is a factor of a few higher than in cores of Galactic molecular clouds. This is probably due to a somewhat higher gas temperature and possibly a considerably higher electron abundance in N159. The estimated HCN/DCN abundance ratio is 60_-35_^+50^ (total 2σ uncertainties).

  19. Cosmological parameter estimation with large scale structure observations

    SciTech Connect

    Dio, Enea Di; Montanari, Francesco; Durrer, Ruth; Lesgourgues, Julien E-mail: Francesco.Montanari@unige.ch E-mail: Julien.Lesgourgues@cern.ch

    2014-01-01

    We estimate the sensitivity of future galaxy surveys to cosmological parameters, using the redshift dependent angular power spectra of galaxy number counts, C{sub ℓ}(z{sub 1},z{sub 2}), calculated with all relativistic corrections at first order in perturbation theory. We pay special attention to the redshift dependence of the non-linearity scale and present Fisher matrix forecasts for Euclid-like and DES-like galaxy surveys. We compare the standard P(k) analysis with the new C{sub ℓ}(z{sub 1},z{sub 2}) method. We show that for surveys with photometric redshifts the new analysis performs significantly better than the P(k) analysis. For spectroscopic redshifts, however, the large number of redshift bins which would be needed to fully profit from the redshift information, is severely limited by shot noise. We also identify surveys which can measure the lensing contribution and we study the monopole, C{sub 0}(z{sub 1},z{sub 2})

  20. Interactive analysis of a large aperture Earth observations satellite

    NASA Technical Reports Server (NTRS)

    Wright, R. L.; Deryder, D. D.; Ferebee, M. J., Jr.; Smith, J. C.

    1983-01-01

    A system level design and analysis has been conducted on an Earth Observation Satellite (EOS) system using the Interactive Design and Evaluation of Advanced Spacecraft (IDEAS) computer-aided design and analysis program. The IDEAS program consists of about 40 user-friendly technical modules and an interactive graphics display. The reflector support system and feed mast of the EOS spacecraft are constructed with box-truss structural concept, a lattice configuration which can be packaged for delivery in a single Shuttle flight and deployed in orbit. The deployed spacecraft consists of a 120-m by 60-m parabolic focal axis. The spacecraft was modeled for structural, thermal, and control systems analysis and structural elements were designed. On-orbit dynamic and thermal loading analyses were conducted; spacecraft weights and developmental and first unit costs were determined.

  1. Large-scale Observations of the Magnetopause by Cluster

    NASA Astrophysics Data System (ADS)

    Foullon, Claire

    2014-05-01

    The magnetopause and its adjacent boundary layers are a key science target for many satellite missions. They have been sampled, at the same time, either locally by a maximum of 4 to 5 closely spaced spacecraft (from the Cluster constellation and the Double Star TC-1 satellite) or on larger scales by missions such as Geotail, Cluster and THEMIS. Unfortunately, none of the spacecraft configurations has so far permitted the 'evolution' of perturbations along their main direction of propagation to be tracked. The study of the evolution of magnetic field and plasma perturbations, such as Kelvin-Helmholtz (KH) waves or Flux Transfer Events (FTEs), together with the (associated or not) generation of Kinetic Alfvén Waves (KAWs) and the turbulence developing at the flank magnetopause boundary layer, is important for our understanding of the mechanisms that mediate solar wind plasma entry into the magnetosphere, i.e. magnetic reconnection and diffusive processes. The Cluster Guest Investigator (GI) proposal implemented in November 2012 targeted inter-spacecraft separations of ~1 RE necessary to relate disturbances and deduce their evolution. It resulted in separations of up to 36,000 km across the constellation at the magnetopause and was the largest separation ever for the Cluster mission. In this invited talk, I will present the first results from the Cluster GI observations of magnetopause boundary layer.

  2. Large-scale Observations of the Magnetopause by Cluster (Invited)

    NASA Astrophysics Data System (ADS)

    Foullon, C.

    2013-12-01

    The magnetopause and its adjacent boundary layers are a key science target for many satellite missions. They have been sampled, at the same time, either locally by a maximum of 4 to 5 closely spaced spacecraft (from the Cluster constellation and the Double Star TC-1 satellite) or on larger scales by missions such as Geotail, Cluster and THEMIS. Unfortunately, none of the spacecraft configurations has so far permitted the 'evolution' of perturbations along their main direction of propagation to be tracked. The study of the evolution of magnetic field and plasma perturbations, such as Kelvin-Helmholtz (KH) waves or Flux Transfer Events (FTEs), together with the (associated or not) generation of Kinetic Alfvén Waves (KAWs) and the turbulence developing at the flank magnetopause boundary layer, is important for our understanding of the mechanisms that mediate solar wind plasma entry into the magnetosphere, i.e. magnetic reconnection and diffusive processes. The Cluster Guest Investigator (GI) proposal implemented in November 2012 targeted inter-spacecraft separations of ~1 RE necessary to relate disturbances and deduce their evolution. It resulted in separations of up to 36,000 km across the constellation at the magnetopause and was the largest separation ever for the Cluster mission. In this invited talk, I will present the first results from the Cluster GI observations of magnetopause boundary layer.

  3. GIS for large-scale watershed observational data model

    NASA Astrophysics Data System (ADS)

    Patino-Gomez, Carlos

    Because integrated management of a river basin requires the development of models that are used for many purposes, e.g., to assess risks and possible mitigation of droughts and floods, manage water rights, assess water quality, and simply to understand the hydrology of the basin, the development of a relational database from which models can access the various data needed to describe the systems being modeled is fundamental. In order for this concept to be useful and widely applicable, however, it must have a standard design. The recently developed ArcHydro data model facilitates the organization of data according to the "basin" principle and allows access to hydrologic information by models. The development of a basin-scale relational database for the Rio Grande/Bravo basin implemented in a Geographic Information System is one of the contributions of this research. This geodatabase represents the first major attempt to establish a more complete understanding of the basin as a whole, including spatial and temporal information obtained from the United States of America and Mexico. Difficulties in processing raster datasets over large regions are studied in this research. One of the most important contributions is the application of a Raster-Network Regionalization technique, which utilizes raster-based analysis at the subregional scale in an efficient manner and combines the resulting subregional vector datasets into a regional database. Another important contribution of this research is focused on implementing a robust structure for handling huge temporal data sets related to monitoring points such as hydrometric and climatic stations, reservoir inlets and outlets, water rights, etc. For the Rio Grande study area, the ArcHydro format is applied to the historical information collected in order to include and relate these time series to the monitoring points in the geodatabase. Its standard time series format is changed to include a relationship to the agency from

  4. New Observations Reveal How the Martian Residual South Polar Cap Develops Quasi-Circular Pits, Heart-Shaped Pits, Troughs, and Moats

    NASA Astrophysics Data System (ADS)

    Buhler, Peter Benjamin; Ingersoll, Andrew P.; Ehlmann, Bethany; Fassett, Caleb; Head, James W.

    2016-10-01

    The martian residual south polar cap (RSPC) is a ~1-10 m thick deposit of CO2 ice perched on the much larger H2O ice cap. Because it is the only known CO2 reservoir annually exchanging with the predominantly-CO2 martian atmosphere, understanding its evolution is important to understanding the modern martian climate. The 8 x 105 m2 RSPC is perennial and characterized by mesas dissected by quasi-circular pits, heart-shaped pits, linear troughs and ridges, and moats (a low, CO2-free boundary surrounding a mesa wholly contained within another mesa) that evolve at meter-scales each year [1,2]. However, the underlying processes leading to the development of these landforms have not yet been described. Using repeat-coverage HiRISE (25-50 cm/px) imagery, we observe previously undescribed features on the RSPC, which reveal the processes leading to the emergence of its meter-to-kilometer-scale morphology. We observe dark fans emanating from the sides of RSPC mesas and widespread fracturing and collapse of the upper surface of mesas, which we interpret as evidence for sublimation in the interiors of mesas. On relatively smooth areas of the RSPC, even small relief (~10 cm) collapses generate surface roughness, which concentrates sunlight and enhances sublimation, leading to the development of steep, eroding scarps. Typically, CO2 deposition during the winter then smooths terrain and creates gently sloping scarps (although uneven CO2 deposition can also create steep scarps). A collapse that drops down, such that it is entirely bounded by a steep scarp, develops into a quasi-circular pit. However, when a portion of the collapsing area remains attached to the upper surface, the perimeter is partially bounded by a steep scarp and partially bounded by a gently sloping ramp, which develops into either a heart-shaped pit, linear trough, or moat, depending on the local interplay between deposition and erosion. Finally, we use the spatial distribution of pits in order to determine the

  5. Negative circular polarization as a universal property of quantum dots

    SciTech Connect

    Taylor, Matthew W.; Spencer, Peter; Murray, Ray

    2015-03-23

    This paper shows that negative circular polarization, a spin flip of polarized carriers resulting in emission of opposite helicity, can be observed in undoped, n-doped, and p-doped InAs/GaAs quantum dots. These results contradict the usual interpretation of the effect. We show using power dependent and time resolved spectroscopy that the generation of negative circular polarization correlates with excited state emission. Furthermore, a longer spin lifetime of negatively polarized excitons is observed where emission is largely ground state in character.

  6. Circular inferences in schizophrenia.

    PubMed

    Jardri, Renaud; Denève, Sophie

    2013-11-01

    A considerable number of recent experimental and computational studies suggest that subtle impairments of excitatory to inhibitory balance or regulation are involved in many neurological and psychiatric conditions. The current paper aims to relate, specifically and quantitatively, excitatory to inhibitory imbalance with psychotic symptoms in schizophrenia. Considering that the brain constructs hierarchical causal models of the external world, we show that the failure to maintain the excitatory to inhibitory balance results in hallucinations as well as in the formation and subsequent consolidation of delusional beliefs. Indeed, the consequence of excitatory to inhibitory imbalance in a hierarchical neural network is equated to a pathological form of causal inference called 'circular belief propagation'. In circular belief propagation, bottom-up sensory information and top-down predictions are reverberated, i.e. prior beliefs are misinterpreted as sensory observations and vice versa. As a result, these predictions are counted multiple times. Circular inference explains the emergence of erroneous percepts, the patient's overconfidence when facing probabilistic choices, the learning of 'unshakable' causal relationships between unrelated events and a paradoxical immunity to perceptual illusions, which are all known to be associated with schizophrenia.

  7. Real time observation of proteolysis with Fourier transform infrared (FT-IR) and UV-circular dichroism spectroscopy: Watching a protease eat a protein

    NASA Astrophysics Data System (ADS)

    Güler, Günnur; Džafić, Enela; Vorob'ev, Mikhail M.; Vogel, Vitali; Mäntele, Werner

    2011-06-01

    Fourier transform infrared (FT-IR)- and UV-circular dichroism (UV-CD) spectroscopy have been used to study real-time proteolytic digestion of β-lactoglobulin (β-LG) and β-casein (β-CN) by trypsin at various substrate/enzyme ratios in D 2O-buffer at 37 °C. Both techniques confirm that protein substrate looses its secondary structure upon conversion to the peptide fragments. This perturbation alters the backbone of the protein chain resulting in conformational changes and degrading of the intact protein. Precisely, the most significant spectral changes which arise from digestion take place in the amide I and amide II regions. The FT-IR spectra for the degraded β-LG show a decrease around 1634 cm -1, suggesting a decrease of β-sheet structure in the course of hydrolysis. Similarly, the intensity around the 1654 cm -1 band decreases for β-CN digested by trypsin, indicating a reduction in the α-helical part. On the other hand, the intensity around ˜1594 cm -1 and ˜1406 cm -1 increases upon enzymatic breakdown of both substrates, suggesting an increase in the antisymmetric and symmetric stretching modes of free carboxylates, respectively, as released digestion products. Observation of further H/D exchange in the course of digestion manifests the structural opening of the buried groups and accessibility to the core of the substrate. On the basis of the UV-CD spectra recorded for β-LG and β-CN digested by trypsin, the unordered structure increases concomitant with a decrease in the remaining structure, thus, revealing breakdown of the intact protein into smaller fragments. This model study in a closed reaction system may serve as a basis for the much more complex digestion processes in an open reaction system such as the stomach.

  8. High-beta analytic equilibria in circular, elliptical, and D-shaped large aspect ratio axisymmetric configurations with poloidal and toroidal flows

    NASA Astrophysics Data System (ADS)

    López, O. E.; Guazzotto, L.

    2017-03-01

    The Grad-Shafranov-Bernoulli system of equations is a single fluid magnetohydrodynamical description of axisymmetric equilibria with mass flows. Using a variational perturbative approach [E. Hameiri, Phys. Plasmas 20, 024504 (2013)], analytic approximations for high-beta equilibria in circular, elliptical, and D-shaped cross sections in the high aspect ratio approximation are found, which include finite toroidal and poloidal flows. Assuming a polynomial dependence of the free functions on the poloidal flux, the equilibrium problem is reduced to an inhomogeneous Helmholtz partial differential equation (PDE) subject to homogeneous Dirichlet conditions. An application of the Green's function method leads to a closed form for the circular solution and to a series solution in terms of Mathieu functions for the elliptical case, which is valid for arbitrary elongations. To extend the elliptical solution to a D-shaped domain, a boundary perturbation in terms of the triangularity is used. A comparison with the code FLOW [L. Guazzotto et al., Phys. Plasmas 11(2), 604-614 (2004)] is presented for relevant scenarios.

  9. An observer for a deployable antenna. [for large space structure flight experiment

    NASA Technical Reports Server (NTRS)

    Waites, H. B.

    1981-01-01

    An observer is derived for use on an Orbiter-Deployable Antenna configuration. The unique feature of this observer design for this flight experiment is that all the plant inputs are not required to be directly accessible for the observer to ferret out the system states. The observer uses state and rate of the state information to reconstruct the plant states. Results are presented which show how effectively this observer design works for this large space structure flight experiment.

  10. Synthetic-Aperture Coherent Imaging From A Circular Path

    NASA Technical Reports Server (NTRS)

    Jin, Michael Y.

    1995-01-01

    Imaging algorithms based on exact point-target responses. Developed for use in reconstructing image of target from data gathered by radar, sonar, or other transmitting/receiving coherent-signal sensory apparatus following circular observation path around target. Potential applications include: Wide-beam synthetic-aperture radar (SAR) from aboard spacecraft in circular orbit around target planet; SAR from aboard airplane flying circular course at constant elevation around central ground point, toward which spotlight radar beam pointed; Ultrasonic reflection tomography in medical setting, using one transducer moving in circle around patient or else multiple transducers at fixed positions on circle around patient; and Sonar imaging of sea floor to high resolution, without need for large sensory apparatus.

  11. Modeling a decrease in hydraulic losses during turbulent flow in a U-bend channel with a circular cavern with a large opening angle

    NASA Astrophysics Data System (ADS)

    Isaev, S. A.; Kalinin, E. I.; Tereshkin, A. A.; Usachov, A. E.

    2015-03-01

    The Reynolds equations for incompressible viscous fluid, closed using the Menter shear-stress-transfer model modified with allowance for the curvature of flow lines, have been numerically solved using multiblock computational technologies. The obtained solution has been used to calculate the turbulent flow in a U-bend channel containing a circular cavern with a variable opening angle. Predictions based on the results of numerical simulations agree well with the experimental data of Savelsberg and Castro at moderate cavern opening angles. It is established that hydraulic losses in a U-bend channel with completely open cavern are significantly (by ˜25%) decreased as compared to those in a smooth channel at Re = 105.

  12. HST Observations of a Large-Amplitude, Long-Period Trojan: (11351) Leucus

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.; Levison, Harold F.; Buie, Marc W.; Grundy, William M.

    2016-10-01

    (11351) Leucus (1997 TS25) is a Trojan that is notable for having one of the longest known rotation periods of any small body, T=514 h. A possible cause for this long period would be the existence of a tidally locked binary similar to the already-known long period binary Trojan, (617) Patroclus. If this were the case, the system would become tidally circularized in a time short compared to the age of the solar system. In such a case, the components would be separated by ~0.18 arcsec at lightcurve maximum, resolvable by WFC3. We carried out observations in June 2016, coordinated with groundbased observations to schedule near a maximum to test whether (11351) Leucus is binary. We describe the results of these observations.Observations of (11351) Leucus are of particular interest because it is a target of the Lucy mission, a Discovery mission currently in phase A and one of five that may be selected in early 2017. Searches for binary Trojans also offer multiple scientific benefits independent of mission status. Orbit-derived mass and density can be used to constrain planetary migration models. Low density is characteristic of bodies found in the dynamically cold Kuiper Belt, a remnant of the solar system's protoplanetary disk. Only one undisputed density has been measured in the Trojans, that of the binary (617) Patroclus, which has a low density of 0.8 g/cm3, similar to the low densities found in the Kuiper Belt. Slow rotators offer a set of targets that are tidally evolved systems and therefore are among the most attractive potential targets for an HST search.

  13. Circular motion in NUT space-time

    NASA Astrophysics Data System (ADS)

    Jefremov, Paul I.; Perlick, Volker

    2016-12-01

    We consider circular motion in the NUT (Newman-Unti-Tamburino) space-time. Among other things, we determine the location of circular time-like geodesic orbits, in particular of the innermost stable circular orbit (ISCO) and of the marginally bound circular orbit. Moreover, we discuss the von Zeipel cylinders with respect to the stationary observers and with respect to the zero angular momentum observers (ZAMOs). We also investigate the relation of von Zeipel cylinders to inertial forces, in particular in the ultra-relativistic limit. Finally, we generalise the construction of thick accretion tori (‘Polish doughnuts’) which are well known on the Schwarzschild or Kerr background to the case of the NUT metric. We argue that, in principle, an NUT source could be distinguished from a Schwarzschild or Kerr source by observing the features of circular matter flows in its neighbourhood.

  14. Large scale evaluation of soil moisture retrievals from passive microwave observations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For several years passive microwave observations have been used to retrieve surface soil moisture from the Earth’s surface. Several satellite sensors such as the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) and WindSat have been used for this purpose using multi-channel observations. Large sc...

  15. Fecal virome of healthy chickens reveals a large diversity of the eukaryote viral community, including novel circular single-stranded DNA viruses.

    PubMed

    Lima, Diane; Cibulski, Samuel Paulo; Finkler, Fabrine; Teixeira, Thais; Varela, Ana Paula; Cerva, Cristine; Loiko, Márcia; Scheffer, Camila; Dos Santos, Helton; Mayer, Fabiana; Roehe, Paulo

    2017-01-18

    This study is focused on the identification of the fecal virome of healthy chickens raised in high-density, export-driven poultry farms in Brazil. Following high-throughput sequencing, a total of 7,743 de novo-assembled contigs were constructed and compared with known nucleotide/amino acid sequences from the GenBank database. Analyses with BLASTx revealed that 279 contigs (4%) were related to sequences of eukaryotic viruses. Viral genome sequences (total or partial) indicative of members of recognized viral families, including Adenoviridae, Caliciviridae, Circoviridae, Parvoviridae, Picobirnaviridae, Picornaviridae and Reoviridae, were identified, some of those representing novel genotypes. In addition, a range of circular replication-associated protein encoding (CRESS) DNA viruses, were also identified. The characterization of the fecal virome of healthy chickens described here provides not only a description of the viruses encountered in such niche but should also represent a baseline for future studies comparing viral populations in healthy and diseased chicken flocks. Moreover, it may also be relevant for human health, since chickens represent a significant proportion of the animal protein consumed worldwide.

  16. Non-Linear Dynamics and Stability of Circular Cylindrical Shells Containing Flowing Fluid, Part II: Large-Amplitude Vibrations Without Flow

    NASA Astrophysics Data System (ADS)

    AMABILI, M.; PELLICANO, F.; PAÏDOUSSIS, M. P.

    1999-12-01

    The non-linear response of empty and fluid-filled circular cylindrical shells to harmonic excitations is investigated. Both modal and point excitations have been considered. The model is suitable to study simply supported shells with and without axial constraints. Donnell's non-linear shallow-shell theory is used. The boundary conditions on radial displacement and the continuity of circumferential displacement are exactly satisfied. The radial deflection of the shell is expanded by using a basis of seven linear modes. The effect of internal quiescent, incompressible and inviscid fluid is investigated. The equations of motion, obtained in Part I of this study, are studied by using a code based on the collocation method. The validation of the present model is obtained by comparison with other authoritative results. The effect of the number of axisymmetric modes used in the expansion on the response of the shell is investigated, clarifying questions open for a long time. The results show the occurrence of travelling wave response in the proximity of the resonance frequency, the fundamental role of the first and third axisymmetric modes in the expansion of the radial deflection with one longitudinal half-wave, and limit cycle responses. Modes with two longitudinal half-waves are also investigated.

  17. An interactive environment for the analysis of large Earth observation and model data sets

    NASA Technical Reports Server (NTRS)

    Bowman, Kenneth P.; Walsh, John E.; Wilhelmson, Robert B.

    1993-01-01

    We propose to develop an interactive environment for the analysis of large Earth science observation and model data sets. We will use a standard scientific data storage format and a large capacity (greater than 20 GB) optical disk system for data management; develop libraries for coordinate transformation and regridding of data sets; modify the NCSA X Image and X DataSlice software for typical Earth observation data sets by including map transformations and missing data handling; develop analysis tools for common mathematical and statistical operations; integrate the components described above into a system for the analysis and comparison of observations and model results; and distribute software and documentation to the scientific community.

  18. An interactive environment for the analysis of large Earth observation and model data sets

    NASA Technical Reports Server (NTRS)

    Bowman, Kenneth P.; Walsh, John E.; Wilhelmson, Robert B.

    1992-01-01

    We propose to develop an interactive environment for the analysis of large Earth science observation and model data sets. We will use a standard scientific data storage format and a large capacity (greater than 20 GB) optical disk system for data management; develop libraries for coordinate transformation and regridding of data sets; modify the NCSA X Image and X Data Slice software for typical Earth observation data sets by including map transformations and missing data handling; develop analysis tools for common mathematical and statistical operations; integrate the components described above into a system for the analysis and comparison of observations and model results; and distribute software and documentation to the scientific community.

  19. SPITZER, VERY LARGE TELESCOPE, AND VERY LARGE ARRAY OBSERVATIONS OF THE GALACTIC LUMINOUS BLUE VARIABLE CANDIDATE HD 168625

    SciTech Connect

    Umana, G.; Buemi, C. S.; Trigilio, C.; Leto, P.; Hora, J. L.

    2010-08-01

    We present mid-IR and radio observations of the Galactic luminous blue variables (LBVs) candidate HD 168625 and its associated nebula. We obtained mid-IR spectroscopic observations using the Infrared Spectrograph on board the Spitzer Space Telescope, and performed mid-IR and radio imaging observations using VISIR on the Very Large Telescope and the Very Large Array with comparable angular resolution. Our spectroscopic observations detected spectral features attributable to polycyclic aromatic hydrocarbons (PAHs) and therefore indicate the presence of a photodissociation region (PDR) around the ionized nebula. This result increases the number of LBVs and LBV candidates where a PDR has been found, confirming the importance of such a component in the total mass-loss budget of the central object during this elusive phase of massive star evolution. We have analyzed and compared the mid-IR and radio maps, and derive several results concerning the associated nebula. There is evidence for grain distribution variations across the nebula, with a predominant contribution from bigger grains in the northern part of the nebula while PAH and smaller grains are more concentrated in the southern part. A compact radio component located where there is a lack of thermal dust grains corroborates the presence of a shock in the southern nebula, which could arise as a consequence of the interaction of a fast outflow with the slower, expanding dusty nebula. Such a shock would be a viable means for PAH production as well as for changes in the grain size distribution. Finally, from the detection of a central radio component probably associated with the wind from the central massive supergiant, we derive a current mass-loss rate of M-dot =(1.46{+-}0.15)x10{sup -6} M{sub sun} yr{sup -1}.

  20. Time-resolved demagnetization of Co2MnSi observed using x-ray magnetic circular dichroism and an ultrafast streak camera.

    PubMed

    Opachich, Y P; Comin, A; Bartelt, A F; Young, A T; Scholl, A; Feng, J; Schmalhorst, J; Shin, H J; Engelhorn, K; Risbud, S H; Reiss, G; Padmore, H A

    2010-04-21

    The demagnetization dynamics of the Heusler alloy Co(2)MnSi was studied using picosecond time-resolved x-ray magnetic circular dichroism. The sample was excited using femtosecond laser pulses. In contrast to the sub-picosecond demagnetization of the metal ferromagnet Ni, substantially slower demagnetization with a time constant of 3.5 ± 0.5 ps was measured. This could be explained by a spin-dependent band gap inhibiting the spin-flip scattering of hot electrons in Co(2)MnSi, which is predicted to be half-metallic. A universal demagnetization time constant was measured across a range of pump power levels.

  1. Spectra of circularly polarized radiation from astrophysical OH masers

    NASA Technical Reports Server (NTRS)

    Nedoluha, Gerald E.; Watson, William D.

    1990-01-01

    A striking feature of astrophysical masers is the tendency for either one or the other of the circular polarizations to dominate in the radiation from the strong, widely observed masing transitions of OH at 18 cm. Spectral line profiles are calculated for polarized maser radiation due to the combined effects of a velocity gradient and, as is indicated for these transitions, a Zeeman splitting that is at least comparable with the thermal contributions to the breadths of the spectral lines. The resulting spectral features are similar in appearance, including the presence of large net circular polarization and narrow line breadths, to the commonly observed spectra of OH masers in molecular clouds. The calculations presented here are performed as a function of frequency without making the approximations of a large velocity gradient. Rapid cross relaxation, which has been advocated by others for the OH masers, is assumed.

  2. CME Brightness at Large Elongations: Application to LASCO and SMEI Observations

    NASA Astrophysics Data System (ADS)

    Vourlidas, A.; Webb, D. F.; Morrill, J. S.; Jackson, B. V.

    2006-12-01

    The traditional analysis of the CME brightness relied on the assumption that all lines of sight through the CME were parallel due to the large distance between the observer and the event. However, this assumption is not correct when CME observations at large distances from the Sun are concerned. In a recent paper (Vourlidas & Howard 2006) we have outlined the proper geometry and presented a few theoretical predictions about the brightness evolution of CME launched at various angles relative to the Sun-observer line. In this talk, we use LASCO and SMEI observations of the same events to test our predictions and see how we can use our theoretical framework to interpret the observed CME structures.

  3. [Circular migration in Indonesia].

    PubMed

    Mantra, I B

    1979-12-01

    The author examines circular migration in Indonesia, with primary focus on the 1970s. It is found that circular, or repeated return migration, generally occurs over short distances and for short periods and is more frequent than lifetime migration. The relationships between improvements in the national transport system, access to labor force opportunities in both the formal and informal sectors of the economy, and circular migration are discussed.

  4. Contemporaneous VLBA 5 GHz Observations of Large Area Telescope Detected Blazars

    DTIC Science & Technology

    2012-01-10

    blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma - ray Space Telescope have been observed contemporaneously by the Very Long...galaxies: jets – galaxies: nuclei – gamma rays : galaxies – radio continuum: galaxies 1. INTRODUCTION The Large Area Telescope (LAT; Atwood et al. 2009...on board the Fermi Gamma - ray Space Telescope is a wide-field telescope covering the energy range from about 20 MeV to more than 300 GeV. It has been

  5. Direct observation of high-spin states in manganese dimer and trimer cations by x-ray magnetic circular dichroism spectroscopy in an ion trap

    SciTech Connect

    Zamudio-Bayer, V.; Hirsch, K.; Langenberg, A.; Kossick, M.; Ławicki, A.; Lau, J. T.; Terasaki, A.; Issendorff, B. von

    2015-06-21

    The electronic structure and magnetic moments of free Mn{sub 2}{sup +} and Mn{sub 3}{sup +} are characterized by 2p x-ray absorption and x-ray magnetic circular dichroism spectroscopy in a cryogenic ion trap that is coupled to a synchrotron radiation beamline. Our results directly show that localized magnetic moments of 5 μ{sub B} are created by 3d{sup 5}({sup 6}S) states at each ionic core, which are coupled ferromagnetically to form molecular high-spin states via indirect exchange that is mediated in both cases by a delocalized valence electron in a singly occupied 4s derived antibonding molecular orbital with an unpaired spin. This leads to total magnetic moments of 11 μ{sub B} for Mn{sub 2}{sup +} and 16 μ{sub B} for Mn{sub 3}{sup +}, with no contribution of orbital angular momentum.

  6. A bifunctional amorphous polymer exhibiting equal linear and circular photoinduced birefringences.

    PubMed

    Royes, Jorge; Provenzano, Clementina; Pagliusi, Pasquale; Tejedor, Rosa M; Piñol, Milagros; Oriol, Luis

    2014-11-01

    The large and reversible photoinduced linear and circular birefringences in azo-compounds are at the basis of the interest in these materials, which are potentially useful for several applications. Since the onset of the linear and circular anisotropies relies on orientational processes, which typically occur on the molecular and supramolecular length scale, respectively, a circular birefringence at least one order of magnitude lower than the linear one is usually observed. Here, the synthesis and characterization of an amorphous polymer with a dimeric repeating unit containing a cyanoazobenzene and a cyanobiphenyl moiety are reported, in which identical optical linear and circular birefringences are induced for proper light dose and ellipticity. A pump-probe technique and an analytical method based on the Stokes-Mueller formalism are used to investigate the photoinduced effects and to evaluate the anisotropies. The peculiar photoresponse of the polymer makes it a good candidate for applications in smart functional devices.

  7. Wideband very large array observations of A2256. I. Continuum, rotation measure, and spectral imaging

    SciTech Connect

    Owen, Frazer N.; Rau, Urvashi; Bhatnagar, Sanjay; Kogan, Leonid; Rudnick, Lawrence; Jean Eilek

    2014-10-10

    We report new observations of A2256 with the Karl G. Jansky Very Large Array (VLA) at frequencies between 1 and 8 GHz. These observations take advantage of the 2:1 bandwidths available during a single observation to study the spectral index, polarization, and rotation measure as well as using the associated higher sensitivity per unit time to image total intensity features down to ∼0.''5 resolution. We find that the Large Relic, which dominates the cluster, is made up of a complex of filaments that show correlated distributions in intensity, spectral index, and fractional polarization. The rotation measure varies across the face of the Large Relic but is not well correlated with the other properties of the source. The shape of individual filaments suggests that the Large Relic is at least 25 kpc thick. We detect a low surface brightness arc connecting the Large Relic to the Halo and other radio structures, suggesting a physical connection between these features. The center of the F-complex is dominated by a very steep-spectrum, polarized, ring-like structure, F2, without an obvious optical identification, but the entire F-complex does have interesting morphological similarities to the radio structure of NGC 1265. Source C, the Long Tail, is unresolved in width near the galaxy core and is ≲ 100 pc in diameter there. This morphology suggests either that C is a one-sided jet or that the bending of the tails takes place very near the core, consistent with the parent galaxy having undergone extreme stripping. Overall it seems that many of the unusual phenomena can be understood in the context of A2256 being near the pericenter of a slightly off-axis merger between a cluster and a smaller group. Given the lack of evidence for a strong shock associated with the Large Relic, other models should be considered, such as reconnection between two large-scale magnetic domains.

  8. ARRIVAL TIME CALCULATION FOR INTERPLANETARY CORONAL MASS EJECTIONS WITH CIRCULAR FRONTS AND APPLICATION TO STEREO OBSERVATIONS OF THE 2009 FEBRUARY 13 ERUPTION

    SciTech Connect

    Moestl, C.; Rollett, T.; Temmer, M.; Veronig, A. M.; Biernat, H. K.; Lugaz, N.; Farrugia, C. J.; Galvin, A. B.; Davies, J. A.; Harrison, R. A.; Crothers, S.; Luhmann, J. G.; Zhang, T. L.; Baumjohann, W.

    2011-11-01

    One of the goals of the NASA Solar TErestrial RElations Observatory (STEREO) mission is to study the feasibility of forecasting the direction, arrival time, and internal structure of solar coronal mass ejections (CMEs) from a vantage point outside the Sun-Earth line. Through a case study, we discuss the arrival time calculation of interplanetary CMEs (ICMEs) in the ecliptic plane using data from STEREO/SECCHI at large elongations from the Sun in combination with different geometric assumptions about the ICME front shape [fixed-{Phi} (FP): a point and harmonic mean (HM): a circle]. These forecasting techniques use single-spacecraft imaging data and are based on the assumption of constant velocity and direction. We show that for the slow (350 km s{sup -1}) ICME on 2009 February 13-18, observed at quadrature by the two STEREO spacecraft, the results for the arrival time given by the HM approximation are more accurate by 12 hr than those for FP in comparison to in situ observations of solar wind plasma and magnetic field parameters by STEREO/IMPACT/PLASTIC, and by 6 hr for the arrival time at Venus Express (MAG). We propose that the improvement is directly related to the ICME front shape being more accurately described by HM for an ICME with a low inclination of its symmetry axis to the ecliptic. In this case, the ICME has to be tracked to >30{sup 0} elongation to obtain arrival time errors < {+-} 5 hr. A newly derived formula for calculating arrival times with the HM method is also useful for a triangulation technique assuming the same geometry.

  9. The x ray properties of a large, uniform QSO sample: Einstein observations of the LBQS

    NASA Technical Reports Server (NTRS)

    Margon, B.; Anderson, S. F.; Xu, X.; Green, P. J.; Foltz, C. B.

    1992-01-01

    Although there are large numbers of Quasi Stellar Objects (QSO's) now observed in X rays, extensive X-ray observations of uniformly selected, 'complete' QSO samples are more rare. The Large Bright QSO Survey (LBQS) consists of about 1000 objects with well understood properties, most brighter than B = 18.8 and thus amenable to X-ray detections in relatively brief exposures. The sample is thought to be highly complete in the range 0.2 less than z less than 3.3, a significantly broader interval than many other surveys. The Einstein IPC observed 150 of these objects, mostly serendipitously, during its lifetime. We report the results of an analysis of these IPC data, considering not only the 20 percent of the objects we find to have positive X-ray detections, but also the ensemble X-ray properties derived by 'image stacking'.

  10. Large-Amplitude Electrostatic Waves Observed at a Supercritical Interplanetary Shock

    NASA Technical Reports Server (NTRS)

    Wilson, L. B., III; Cattell, C. A.; Kellogg, P. J.; Goetz, K.; Kersten, K.; Kasper, J. C.; Szabo, A.; Wilber, M.

    2010-01-01

    We present the first observations at an interplanetary shock of large-amplitude (> 100 mV/m pk-pk) solitary waves and large-amplitude (approx.30 mV/m pk-pk) waves exhibiting characteristics consistent with electron Bernstein waves. The Bernstein-like waves show enhanced power at integer and half-integer harmonics of the cyclotron frequency with a broadened power spectrum at higher frequencies, consistent with the electron cyclotron drift instability. The Bernstein-like waves are obliquely polarized with respect to the magnetic field but parallel to the shock normal direction. Strong particle heating is observed in both the electrons and ions. The observed heating and waveforms are likely due to instabilities driven by the free energy provided by reflected ions at this supercritical interplanetary shock. These results offer new insights into collisionless shock dissipation and wave-particle interactions in the solar wind.

  11. Petermann Glacier, North Greenland: Large Ice-Discharge Episodes from 20 Years of Satellite Observations

    NASA Astrophysics Data System (ADS)

    Babiker, M.; Johannessen, O. M.; Miles, M. W.; Miles, V. V.

    2009-12-01

    The major marine-terminating outlet glaciers of Greenland can undergo large mass losses through calving of icebergs and bottom melting from floating ice tongues. Recent observations of outlet glaiers around Greenland have shown that large and rapid changes in solid-ice fluxes are possible. The Petermann glacier in remote northern Greenland is the region’s largest floating-tongue glacier (~70 km by 10 km). In summer 2008 a large calving event was observed, as well as large cracks upstream of the remaining calving front, portending a more massive near-term loss. These observations may herald extraordinary and unprecedented change. However, the long-term variability of calving events and ice velocities are poorly known. Our research goal here is to identify the temporal variability and possible trends in solid-ice flux indicators - variability of the calving front and ice velocity - for Petermann glacier. The methodological approach is observational, based primarily on analysis of 20 years of repetitive satellite data over a period starting from 1990, together with sporadic earlier observations. The multisensor data range from high-resolution optical images from Landsat, SPOT and Terra ASTER and high-resolution synthetic aperture radar (SAR) images from ERS and ENVISAT. These disparate data have been imported, geo-registered and analysed within a Geographic Information System. The following measurements are made: (1) delineating changes in the calving front, (2) estimating the area of glacial ice loss during calving events, and (3) estimating the ice-surface velocity using sequential satellite images. We find evidence of a number of previous calving episodes of similar magnitude to the summer 2008. The ice-velocity estimates compare well with other estimates for particular years, and moreover are relatively consistent during the 20-year period. These findings suggest business-as-usual for Petermann glacier; however, a near-term calving event exceeding those observed

  12. Large-scale atmospheric carbon and surface water dynamics inferred from satellite-based observations

    NASA Astrophysics Data System (ADS)

    Jensen, K.; McDonald, K. C.; Krakauer, N.; Schroeder, R.

    2013-12-01

    The sensitivity of Earth's wetlands to observed shifts in global precipitation and temperature patterns and their ability to produce large quantities of climate-active gases are key global change questions. Surface inundation is a crucial state variable that affects the rate of land-atmosphere carbon exchange and the partitioning of carbon between CO2 and CH4. Ground observation networks of large-scale inundation patterns are sparse because they require large fiscal, technological and human resources. Thus, satellite remote sensing products for global inundation dynamics, as well as total water storage and atmospheric carbon, can provide a complete synoptic view of past and current carbon - surface water dynamics over large areas that otherwise could not be assessed. We present results from a correlative analysis between spaceborne measurements of CO2 and CH4 as observed by SCIAMACHY and AIRS, water storage (derived from gravity anomalies provided by NASA's GRACE mission), and inundated water fraction derived from a combination of active and passive microwave remote sensing datasets. A general assessment is conducted globally, and further time-series analysis is focused on four regions of interest: North Amazon, Congo, Ob, and Ganges-Brahmaputra river basins. This analysis was supported by a grant from the NASA Terrestrial Ecology Program and the development of the inundation datasets was supported by the NASA MEaSUREs program.

  13. Large-Scale Covariability Between Aerosol and Precipitation Over the 7-SEAS Region: Observations and Simulations

    NASA Technical Reports Server (NTRS)

    Huang, Jingfeng; Hsu, N. Christina; Tsay, Si-Chee; Zhang, Chidong; Jeong, Myeong Jae; Gautam, Ritesh; Bettenhausen, Corey; Sayer, Andrew M.; Hansell, Richard A.; Liu, Xiaohong; Jiang, Jonathan H.

    2012-01-01

    One of the seven scientific areas of interests of the 7-SEAS field campaign is to evaluate the impact of aerosol on cloud and precipitation (http://7-seas.gsfc.nasa.gov). However, large-scale covariability between aerosol, cloud and precipitation is complicated not only by ambient environment and a variety of aerosol effects, but also by effects from rain washout and climate factors. This study characterizes large-scale aerosol-cloud-precipitation covariability through synergy of long-term multi ]sensor satellite observations with model simulations over the 7-SEAS region [10S-30N, 95E-130E]. Results show that climate factors such as ENSO significantly modulate aerosol and precipitation over the region simultaneously. After removal of climate factor effects, aerosol and precipitation are significantly anti-correlated over the southern part of the region, where high aerosols loading is associated with overall reduced total precipitation with intensified rain rates and decreased rain frequency, decreased tropospheric latent heating, suppressed cloud top height and increased outgoing longwave radiation, enhanced clear-sky shortwave TOA flux but reduced all-sky shortwave TOA flux in deep convective regimes; but such covariability becomes less notable over the northern counterpart of the region where low ]level stratus are found. Using CO as a proxy of biomass burning aerosols to minimize the washout effect, large-scale covariability between CO and precipitation was also investigated and similar large-scale covariability observed. Model simulations with NCAR CAM5 were found to show similar effects to observations in the spatio-temporal patterns. Results from both observations and simulations are valuable for improving our understanding of this region's meteorological system and the roles of aerosol within it. Key words: aerosol; precipitation; large-scale covariability; aerosol effects; washout; climate factors; 7- SEAS; CO; CAM5

  14. Observation of coherent pi0 electroproduction on deuterons at large momentum transfer

    SciTech Connect

    Tomasi, Egle; Bimbot, Louis; Danagoulian, Samuel; Gustafsson, Kenneth; Mack, David; Mkrtchyan, Hamlet; Rekalo, M.P.

    2003-03-01

    The first experimental results for coherent $\\pi^0$-electroproduction on the deuteron, $e+d\\to e+d +\\pi^0$, at large momentum transfer, are reported. The experiment was performed at Jefferson Laboratory at an incident electron energy of 4.05 GeV. A large pion production yield has been observed in a kinematical region for 1.1$

  15. Observation of large magnetocaloric effect in HoRu{sub 2}Si{sub 2}

    SciTech Connect

    Paramanik, Tapas Das, Kalipada; Das, I.

    2014-02-28

    Detailed magnetic, magnetotransport, and magnetocaloric measurements on HoRu{sub 2}Si{sub 2} have been performed. In this Letter, we report presence of spin reorientation transition below paramagnetic to antiferromagnetic transition temperature (T{sub N} = 19 K). Large magnetic entropy change 9.1 J/kg K and large negative magnetoresistance ∼21% in a magnetic field of 5 T has been observed around T{sub N}, which is associated with field induced spin-flip metamagnetic transition.

  16. Direct observation of ferromagnetism in grain boundary phase of Nd-Fe-B sintered magnet using soft x-ray magnetic circular dichroism

    SciTech Connect

    Nakamura, T.; Yasui, A.; Kotani, Y.; Iwai, H.; Akiya, T.; Ohkubo, T.; Hono, K.; Hirosawa, S.; Gohda, Y.

    2014-11-17

    We have investigated the magnetism of the grain boundary (GB) phase in a Nd{sub 14.0}Fe{sub 79.7}Cu{sub 0.1}B{sub 6.2} sintered magnet using soft x-ray magnetic circular dichroism (XMCD) at the Fe L{sub 2,3}-edges. Soft XMCD spectra were measured from the fractured surface that was confirmed to be covered with a thin GB phase by Auger electron spectroscopy. The magnetic moment of Fe in the GB phase was estimated to be m{sub GB}=1.4 μ{sub B} at 30 °C using the sum rule analysis for XMCD spectra, which is 60% of that of Fe in the Nd{sub 2}Fe{sub 14}B compound. The temperature dependence of m{sub GB} evaluated with reference to Fe in the Nd{sub 2}Fe{sub 14}B phase indicated that the Curie temperature of the GB phase is more than 50 °C lower compared to that of Nd{sub 2}Fe{sub 14}B.

  17. Orbital circularization of a planet accreting disk gas: the formation of distant jupiters in circular orbits based on a core accretion model

    SciTech Connect

    Kikuchi, Akihiro; Higuchi, Arika; Ida, Shigeru E-mail: higuchia@geo.titech.ac.jp

    2014-12-10

    Recently, gas giant planets in nearly circular orbits with large semimajor axes (a ∼ 30-1000 AU) have been detected by direct imaging. We have investigated orbital evolution in a formation scenario for such planets, based on a core accretion model. (1) Icy cores accrete from planetesimals at ≲ 30 AU, (2) they are scattered outward by an emerging nearby gas giant to acquire highly eccentric orbits, and (3) their orbits are circularized through the accretion of disk gas in outer regions, where they spend most of their time. We analytically derived equations to describe the orbital circularization through gas accretion. Numerical integrations of these equations show that the eccentricity decreases by a factor of more than 5 while the planetary mass increases by a factor of 10. Because runaway gas accretion increases planetary mass by ∼10-300, the orbits are sufficiently circularized. On the other hand, a is reduced at most only by a factor of two, leaving the planets in the outer regions. If the relative velocity damping by shock is considered, the circularization slows down, but is still efficient enough. Therefore, this scenario potentially accounts for the formation of observed distant jupiters in nearly circular orbits. If the apocenter distances of the scattered cores are larger than the disk sizes, their a shrink to a quarter of the disk sizes; the a-distribution of distant giants could reflect the outer edges of the disks in a similar way that those of hot jupiters may reflect inner edges.

  18. Comparing GOSAT observations of localized CO2 enhancements by large emitters with inventory-based estimates

    NASA Astrophysics Data System (ADS)

    Janardanan, Rajesh; Maksyutov, Shamil; Oda, Tomohiro; Saito, Makoto; Kaiser, Johannes W.; Ganshin, Alexander; Stohl, Andreas; Matsunaga, Tsuneo; Yoshida, Yukio; Yokota, Tatsuya

    2016-04-01

    We employed an atmospheric transport model to attribute column-averaged CO2 mixing ratios (XCO2) observed by Greenhouse gases Observing SATellite (GOSAT) to emissions due to large sources such as megacities and power plants. XCO2 enhancements estimated from observations were compared to model simulations implemented at the spatial resolution of the satellite observation footprint (0.1° × 0.1°). We found that the simulated XCO2 enhancements agree with the observed over several continental regions across the globe, for example, for North America with an observation to simulation ratio of 1.05 ± 0.38 (p < 0.1), but with a larger ratio over East Asia (1.22 ± 0.32; p < 0.05). The obtained observation-model discrepancy (22%) for East Asia is comparable to the uncertainties in Chinese emission inventories (~15%) suggested by recent reports. Our results suggest that by increasing the number of observations around emission sources, satellite instruments like GOSAT can provide a tool for detecting biases in reported emission inventories.

  19. Comparing GOSAT Observations of Localized CO2 Enhancements by Large Emitters with Inventory-Based Estimates

    NASA Technical Reports Server (NTRS)

    Janardanan, Rajesh; Maksyutov, Shamil; Oda, Tomohiro; Saito, Makoto; Kaiser, Johannes W.; Ganshin, Alexander; Stohl, Andreas; Matsunaga, Tsuneo; Yoshida, Yukio; Yokota, Tatsuya

    2016-01-01

    We employed an atmospheric transport model to attribute column-averaged CO2 mixing ratios (XCO2) observed by Greenhouse gases Observing SATellite (GOSAT) to emissions due to large sources such as megacities and power plants. XCO2 enhancements estimated from observations were compared to model simulations implemented at the spatial resolution of the satellite observation footprint (0.1deg × 0.1deg). We found that the simulated XCO2 enhancements agree with the observed over several continental regions across the globe, for example, for North America with an observation to simulation ratio of 1.05 +/- 0.38 (p<0.1), but with a larger ratio over East Asia (1.22 +/- 0.32; p<0.05). The obtained observation-model discrepancy (22%) for East Asia is comparable to the uncertainties in Chinese emission inventories (approx.15%) suggested by recent reports. Our results suggest that by increasing the number of observations around emission sources, satellite instruments like GOSAT can provide a tool for detecting biases in reported emission inventories.

  20. Characteristics of Electron Distributions Observed During Large Amplitude Whistler Wave Events in the Magnetosphere

    NASA Technical Reports Server (NTRS)

    Wilson, Lynn B., III

    2010-01-01

    We present a statistical study of the characteristics of electron distributions associated with large amplitude whistler waves inside the terrestrial magnetosphere using waveform capture data as an addition of the study by Kellogg et al., [2010b]. We identified three types of electron distributions observed simultaneously with the whistler waves including beam-like, beam/flattop, and anisotropic distributions. The whistlers exhibited different characteristics dependent upon the observed electron distributions. The majority of the waveforms observed in our study have f/fce < or = 0.5 and are observed primarily in the radiation belts outside the plasmapause simultaneously with anisotropic electron distributions. We also present an example waveform capture of the largest magnetic field amplitude (> or = 8 nT pk-pk) whistler wave measured in the radiation belts. The majority of the largest amplitude whistlers occur during magnetically active periods (AE > 200 nT).

  1. ISIS observations of auroral particles and large-scale Birkeland currents

    NASA Technical Reports Server (NTRS)

    Klumpar, D. M.

    1981-01-01

    Simultaneous electron and positive ion observations made with single-component magnetic perturbations on the ISIS-2 satellite are used to compare and contrast the relationships between primary and secondary auroral particle distributions at 5 eV-15 keV, and the large-scale Birkeland currents, in the pre- and post-midnight local time sectors. No unique relation is found between the regions of the Birkeland current system and regions of auroral particle distribution, though repeatable systematics in the region of upward-directed current are observed, and little evidence exists in either local time sector for the direct detection of the downward current-associated current carriers.

  2. Trains of large Kelvin-Helmholtz billows observed in the Kuroshio above a seamount

    NASA Astrophysics Data System (ADS)

    Chang, Ming-Huei; Jheng, Sin-Ya; Lien, Ren-Chieh

    2016-08-01

    Trains of large Kelvin-Helmholtz (KH) billows within the Kuroshio current at ~230 m depth off southeastern Taiwan and above a seamount were observed by shipboard instruments. The trains of large KH billows were present in a strong shear band along the 0.55 m s-1 isotach within the Kuroshio core; they are presumably produced by flow interactions with the rapidly changing topography. Each individual billow, resembling a cat's eye, had a horizontal length scale of 200 m, a vertical scale of 100 m, and a timescale of 7 min, near the local buoyancy frequency. Overturns were observed frequently in the billow cores and the upper eyelids. The turbulent kinetic energy dissipation rates estimated using the Thorpe scale had an average value of O(10-4) W kg-1 and a maximum value of O(10-3) W kg-1. The turbulence mixing induced by the KH billows may exchange Kuroshio water with the surrounding water masses.

  3. Simultaneous effect of modified gravity and primordial non-Gaussianity in large scale structure observations

    SciTech Connect

    Mirzatuny, Nareg; Khosravi, Shahram; Baghram, Shant; Moshafi, Hossein E-mail: khosravi@mail.ipm.ir E-mail: hosseinmoshafi@iasbs.ac.ir

    2014-01-01

    In this work we study the simultaneous effect of primordial non-Gaussianity and the modification of the gravity in f(R) framework on large scale structure observations. We show that non-Gaussianity and modified gravity introduce a scale dependent bias and growth rate functions. The deviation from ΛCDM in the case of primordial non-Gaussian models is in large scales, while the growth rate deviates from ΛCDM in small scales for modified gravity theories. We show that the redshift space distortion can be used to distinguish positive and negative f{sub NL} in standard background, while in f(R) theories they are not easily distinguishable. The galaxy power spectrum is generally enhanced in presence of non-Gaussianity and modified gravity. We also obtain the scale dependence of this enhancement. Finally we define galaxy growth rate and galaxy growth rate bias as new observational parameters to constrain cosmology.

  4. A Large-Aperture Acoustic Array to Observe Oceanic Density Structure

    DTIC Science & Technology

    1975-12-01

    Subtitle) ._,,, , , : A ^ARGE-APERTURb ^ COUSTIC ARRAY TO ^OBSERVE OCEANIC DENSITY STRUCTURE t 7. AUTHORfj; G. Thomas/Kaye READ INSTRUCTIONS...o CO (M MARINE PHYSICAL LABORATORY of the Scripps Institution of Oceanography San Diego, California 92132 A LARGE APERTURE ACOUSTIC ARRAY TO...Contracts Contract Effective Date: Contract Expiration Date; Amount of Contract: Layered Inhomogeneities N00014-69- A -0200-6038 \\ 1 April 1972 Jiß

  5. Coherently modulated whistler mode waves simultaneously observed over unexpectedly large spatial scales

    NASA Astrophysics Data System (ADS)

    Li, Jinxing; Bortnik, Jacob; Li, Wen; Thorne, Richard M.; Ma, Qianli; Chu, Xiangning; Chen, Lunjin; Kletzing, Craig A.; Kurth, William S.; Hospodarsky, George B.; Wygant, John; Breneman, Aaron; Thaller, Scott

    2017-02-01

    Utilizing simultaneous twin Van Allen Probes observations of whistler mode waves at variable separations, we are able to distinguish the temporal variations from spatial variations, determine the coherence spatial scale, and suggest the possible mechanism of wave modulation. The two probes observed coherently modulated whistler mode waves simultaneously at an unexpectedly large distance up to 4.3 RE over 3 h during a relatively quiet period. The modulation of 150-500 Hz plasmaspheric hiss was correlated with whistler mode waves measured outside the plasmasphere across 3 h in magnetic local time and 3 L shells, revealing that the modulation was temporal in nature. We suggest that the coherent modulation of whistler mode waves was associated with the coherent ULF waves measured over a large scale, which modulate the plasmaspheric density and result in the modulation of hiss waves via local amplification. In a later period, the 500-1500 Hz periodic rising-tone whistler mode waves were strongly correlated when the two probes traversed large spatial regions and even across the plasmapause. These periodic rising-tone emissions recurred with roughly the same period as the ULF wave, but there was no one-to-one correspondence, and a cross-correlation analysis suggests that they possibly originated from large L shells although the actual cause needs further investigation.

  6. Radiometer requirements for Earth-observation systems using large space antennas

    NASA Technical Reports Server (NTRS)

    Keafer, L. S., Jr.; Harrington, R. F.

    1983-01-01

    Requirements are defined for Earth observation microwave radiometry for the decade of the 1990's by using large space antenna (LSA) systems with apertures in the range from 50 to 200 m. General Earth observation needs, specific measurement requirements, orbit mission guidelines and constraints, and general radiometer requirements are defined. General Earth observation needs are derived from NASA's basic space science program. Specific measurands include soil moisture, sea surface temperature, salinity, water roughness, ice boundaries, and water pollutants. Measurements are required with spatial resolution from 10 to 1 km and with temporal resolution from 3 days to 1 day. The primary orbit altitude and inclination ranges are 450 to 2200 km and 60 to 98 deg, respectively. Contiguous large scale coverage of several land and ocean areas over the globe dictates large (several hundred kilometers) swaths. Radiometer measurements are made in the bandwidth range from 1 to 37 GHz, preferably with dual polarization radiometers with a minimum of 90 percent beam efficiency. Reflector surface, root mean square deviation tolerances are in the wavelength range from 1/30 to 1/100.

  7. Very Large Array and Jansky Very Large Array observations of the compact radio sources in M8

    SciTech Connect

    Masqué, Josep M.; Rodríguez, Luis F.; Dzib, Sergio

    2014-12-10

    We analyze high-resolution Very Large Array continuum observations of the M8 region carried out at several epochs that span a period of 30 yr. Our maps reveal two compact sources. One is associated with Her 36 SE, a possible companion of the O7 luminous massive star Her 36, and the other is associated with G5.97–1.17, whose proplyd nature was previously established. Using the analyzed data, we do not find significant time variability in any of these sources. The derived spectral index of ≥0.1 for Her 36 SE, the marginal offset of the radio emission with the previous infrared detection, and the associated X-ray emission previously reported suggest the presence of an unresolved interaction region between the strong winds of Her 36 and Her 36 SE. This region would contribute non-thermal contamination to the global wind emission of Her 36, flattening its spectral index. On the other hand, the emission of G5.97–1.17 can also be explained by a mixture of thermal and non-thermal emission components, with different relative contributions of both emission mechanisms along the proplyd. We argue that the shock created by the photo-evaporation flow of the proplyd with the collimated stellar wind of Her 36 accelerates charged particles in G5.97–1.17, producing considerable synchrotron emission. On the contrary, an electron density enhancement at the southwest of G5.97–1.17 makes the thermal emission dominant over this region.

  8. Considerations for observational research using large data sets in radiation oncology.

    PubMed

    Jagsi, Reshma; Bekelman, Justin E; Chen, Aileen; Chen, Ronald C; Hoffman, Karen; Shih, Ya-Chen Tina; Smith, Benjamin D; Yu, James B

    2014-09-01

    The radiation oncology community has witnessed growing interest in observational research conducted using large-scale data sources such as registries and claims-based data sets. With the growing emphasis on observational analyses in health care, the radiation oncology community must possess a sophisticated understanding of the methodological considerations of such studies in order to evaluate evidence appropriately to guide practice and policy. Because observational research has unique features that distinguish it from clinical trials and other forms of traditional radiation oncology research, the International Journal of Radiation Oncology, Biology, Physics assembled a panel of experts in health services research to provide a concise and well-referenced review, intended to be informative for the lay reader, as well as for scholars who wish to embark on such research without prior experience. This review begins by discussing the types of research questions relevant to radiation oncology that large-scale databases may help illuminate. It then describes major potential data sources for such endeavors, including information regarding access and insights regarding the strengths and limitations of each. Finally, it provides guidance regarding the analytical challenges that observational studies must confront, along with discussion of the techniques that have been developed to help minimize the impact of certain common analytical issues in observational analysis. Features characterizing a well-designed observational study include clearly defined research questions, careful selection of an appropriate data source, consultation with investigators with relevant methodological expertise, inclusion of sensitivity analyses, caution not to overinterpret small but significant differences, and recognition of limitations when trying to evaluate causality. This review concludes that carefully designed and executed studies using observational data that possess these qualities hold

  9. Considerations for Observational Research Using Large Data Sets in Radiation Oncology

    SciTech Connect

    Jagsi, Reshma; Bekelman, Justin E.; Chen, Aileen; Chen, Ronald C.; Hoffman, Karen; Tina Shih, Ya-Chen; Smith, Benjamin D.; Yu, James B.

    2014-09-01

    The radiation oncology community has witnessed growing interest in observational research conducted using large-scale data sources such as registries and claims-based data sets. With the growing emphasis on observational analyses in health care, the radiation oncology community must possess a sophisticated understanding of the methodological considerations of such studies in order to evaluate evidence appropriately to guide practice and policy. Because observational research has unique features that distinguish it from clinical trials and other forms of traditional radiation oncology research, the International Journal of Radiation Oncology, Biology, Physics assembled a panel of experts in health services research to provide a concise and well-referenced review, intended to be informative for the lay reader, as well as for scholars who wish to embark on such research without prior experience. This review begins by discussing the types of research questions relevant to radiation oncology that large-scale databases may help illuminate. It then describes major potential data sources for such endeavors, including information regarding access and insights regarding the strengths and limitations of each. Finally, it provides guidance regarding the analytical challenges that observational studies must confront, along with discussion of the techniques that have been developed to help minimize the impact of certain common analytical issues in observational analysis. Features characterizing a well-designed observational study include clearly defined research questions, careful selection of an appropriate data source, consultation with investigators with relevant methodological expertise, inclusion of sensitivity analyses, caution not to overinterpret small but significant differences, and recognition of limitations when trying to evaluate causality. This review concludes that carefully designed and executed studies using observational data that possess these qualities hold

  10. CAN LARGE TIME DELAYS OBSERVED IN LIGHT CURVES OF CORONAL LOOPS BE EXPLAINED IN IMPULSIVE HEATING?

    SciTech Connect

    Lionello, Roberto; Linker, Jon A.; Mikić, Zoran; Alexander, Caroline E.; Winebarger, Amy R. E-mail: linkerj@predsci.com E-mail: caroline.e.alexander@nasa.gov

    2016-02-20

    The light curves of solar coronal loops often peak first in channels associated with higher temperatures and then in those associated with lower temperatures. The delay times between the different narrowband EUV channels have been measured for many individual loops and recently for every pixel of an active region observation. The time delays between channels for an active region exhibit a wide range of values. The maximum time delay in each channel pair can be quite large, i.e., >5000 s. These large time delays make-up 3%–26% (depending on the channel pair) of the pixels where a trustworthy, positive time delay is measured. It has been suggested that these time delays can be explained by simple impulsive heating, i.e., a short burst of energy that heats the plasma to a high temperature, after which the plasma is allowed to cool through radiation and conduction back to its original state. In this paper, we investigate whether the largest observed time delays can be explained by this hypothesis by simulating a series of coronal loops with different heating rates, loop lengths, abundances, and geometries to determine the range of expected time delays between a set of four EUV channels. We find that impulsive heating cannot address the largest time delays observed in two of the channel pairs and that the majority of the large time delays can only be explained by long, expanding loops with photospheric abundances. Additional observations may rule out these simulations as an explanation for the long time delays. We suggest that either the time delays found in this manner may not be representative of real loop evolution, or that the impulsive heating and cooling scenario may be too simple to explain the observations, and other potential heating scenarios must be explored.

  11. Simultaneous Solar Maximum Mission (SMM) and Very Large Array (VLA) observations of solar active regions

    NASA Technical Reports Server (NTRS)

    Willson, Robert F.

    1991-01-01

    Very Large Array observations at 20 cm wavelength can detect the hot coronal plasma previously observed at soft x ray wavelengths. Thermal cyclotron line emission was detected at the apex of coronal loops where the magnetic field strength is relatively constant. Detailed comparison of simultaneous Solar Maximum Mission (SMM) Satellite and VLA data indicate that physical parameters such as electron temperature, electron density, and magnetic field strength can be obtained, but that some coronal loops remain invisible in either spectral domain. The unprecedent spatial resolution of the VLA at 20 cm wavelength showed that the precursor, impulsive, and post-flare components of solar bursts originate in nearby, but separate loops or systems of loops.. In some cases preburst heating and magnetic changes are observed from loops tens of minutes prior to the impulsive phase. Comparisons with soft x ray images and spectra and with hard x ray data specify the magnetic field strength and emission mechanism of flaring coronal loops. At the longer 91 cm wavelength, the VLA detected extensive emission interpreted as a hot 10(exp 5) K interface between cool, dense H alpha filaments and the surrounding hotter, rarefield corona. Observations at 91 cm also provide evidence for time-correlated bursts in active regions on opposite sides of the solar equator; they are attributed to flare triggering by relativistic particles that move along large-scale, otherwise-invisible, magnetic conduits that link active regions in opposite hemispheres of the Sun.

  12. Simulating observations with HARMONI: the integral field spectrograph for the European Extremely Large Telescope

    NASA Astrophysics Data System (ADS)

    Zieleniewski, Simon; Thatte, Niranjan; Kendrew, Sarah; Houghton, Ryan; Tecza, Matthias; Clarke, Fraser; Fusco, Thierry; Swinbank, Mark

    2014-07-01

    With the next generation of extremely large telescopes commencing construction, there is an urgent need for detailed quantitative predictions of the scientific observations that these new telescopes will enable. Most of these new telescopes will have adaptive optics fully integrated with the telescope itself, allowing unprecedented spatial resolution combined with enormous sensitivity. However, the adaptive optics point spread function will be strongly wavelength dependent, requiring detailed simulations that accurately model these variations. We have developed a simulation pipeline for the HARMONI integral field spectrograph, a first light instrument for the European Extremely Large Telescope. The simulator takes high-resolution input data-cubes of astrophysical objects and processes them with accurate atmospheric, telescope and instrumental effects, to produce mock observed cubes for chosen observing parameters. The output cubes represent the result of a perfect data reduc- tion process, enabling a detailed analysis and comparison between input and output, showcasing HARMONI's capabilities. The simulations utilise a detailed knowledge of the telescope's wavelength dependent adaptive op- tics point spread function. We discuss the simulation pipeline and present an early example of the pipeline functionality for simulating observations of high redshift galaxies.

  13. CARMA Large Area Star Formation Survey: Observational Analysis of Filaments in the Serpens South Molecular Cloud

    NASA Astrophysics Data System (ADS)

    Fernández-López, M.; Arce, H. G.; Looney, L.; Mundy, L. G.; Storm, S.; Teuben, P. J.; Lee, K.; Segura-Cox, D.; Isella, A.; Tobin, J. J.; Rosolowsky, E.; Plunkett, A.; Kwon, W.; Kauffmann, J.; Ostriker, E.; Tassis, K.; Shirley, Y. L.; Pound, M.

    2014-08-01

    We present the N2H+ (J = 1 → 0) map of the Serpens South molecular cloud obtained as part of the CARMA Large Area Star Formation Survey. The observations cover 250 arcmin2 and fully sample structures from 3000 AU to 3 pc with a velocity resolution of 0.16 km s-1, and they can be used to constrain the origin and evolution of molecular cloud filaments. The spatial distribution of the N2H+ emission is characterized by long filaments that resemble those observed in the dust continuum emission by Herschel. However, the gas filaments are typically narrower such that, in some cases, two or three quasi-parallel N2H+ filaments comprise a single observed dust continuum filament. The difference between the dust and gas filament widths casts doubt on Herschel ability to resolve the Serpens South filaments. Some molecular filaments show velocity gradients along their major axis, and two are characterized by a steep velocity gradient in the direction perpendicular to the filament axis. The observed velocity gradient along one of these filaments was previously postulated as evidence for mass infall toward the central cluster, but these kind of gradients can be interpreted as projection of large-scale turbulence.

  14. Global Observations of the O+/H+ Ratio During Large Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Valek, P. W.; Goldstein, J.; Jahn, J. M.; McComas, D. J.; Spence, H. E.

    2014-12-01

    During large geomagnetic storms the fraction of magnetospheric oxygen ions increases compared to hydrogen, and is at times even becomes the dominant population. However, it is not well known how this population is energized and transported in the inner magnetosphere. Using a combination of global images from the Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) mission and in situ observations from the Van Allen Probes Hydrogen Oxygen Proton and Electron (HOPE) sensors, we examine how the inner magnetospheres O+/H+ changes during large storms. TWINS provides continuous global observations of medium energy (<50 keV) H and O Energetic Neutral Atoms (ENAs) from the inner magnetosphere. These ENA observations allow us to follow global changes in the composition and energy during storms. HOPE provides 20 eV-45 keV, high-spatial-resolution, in situ measurements of the inner magnetospheric source populations for the ENAs. We present these complementary (global and local) observations of the O+/H+ ratio for selected case study storms, and examine the dependence on local time and storm phase.

  15. The histological observations on the large intestine of the goose (Anser anser) during the pre- and post-hatching periods.

    PubMed

    Líman, Narin; Aslan, Sahin; Gülmez, Nurhayat

    2002-08-01

    The development of the cecum and colon in the goose was investigated during the period from the 15th to 28th day of the incubation and from 1 to 30 days of age after hatching by light microscopy. By day 15 of the incubation, in the cecum and colon, the lumen was surrounded by pseudostratified epithelium. The previllous ridges appeared at 15th and 17th days of the incubation in the colon and ceca, respectively. At the base of previllous ridges, the epithelium changed into a simple prismathic epithelium at 15th and 17th days of the incubation in the colon and cecum, respectively. The villi appeared at the 21st days of the incubation. The crypts and goblet cells appeared on the first day after hatching. In the pre-hatching period, the lamina muscularis mucosa was present only in the colon. The submucosa consisted of loosely aggregated connective tissue in the pre-hatching period. In the post-hatching period, it consisted of a very thin layer of connective tissue. Its presence was only obvious where the cells of the submucosal nerve plexus or occasional large blood vessels considerably increased its thickness. The nerve plexus corresponding to the Auerbach's plexus of the mammalian intestine and submucosal nerve plexus appeared by 15th days of the incubation. From the 15th to 28th day of incubation, the tunica muscularis consisted of circular smooth muscle cells in the ceca. On the 28th day of the incubation a thinner longitudinal muscle layer added to the circular muscle layer. In the colon there was an outer longitudinal and a thicker circular muscle layer.

  16. Estimating the Concentration of Large Raindrops from Polarimetric Radar and Disdrometer Observations

    NASA Technical Reports Server (NTRS)

    Carey, Lawrence D.; Petersen, Walter A; Gatlink, Patrick N.

    2013-01-01

    Estimation of rainfall integral parameters, including radar observables, and empirical relations between them are sensitive to the truncation of the drop size distribution (DSD), particularly at the large drop end. The sensitivity of rainfall integral parameters to the maximum drop diameter (D(sub max)) is exacerbated at C-band since resonance effects are pronounced for large drops in excess of 5 mm diameter (D). Due to sampling limitations, it is often difficult to reliably estimate D(sub max) with disdrometers. The resulting uncertainties in D(sub max0 potentially increase errors in radar retrieval methods, particularly at C-band, that rely on disdrometer observations for DSD input to radar models. In fact, D(sub max) is typically an assumed DSD parameter in the development of radar retrieval methods. Because of these very uncertainties, it is difficult to independently confirm disdrometer estimates of D(sub max) with polarimetric radar observations. A couple of approaches can be taken to reduce uncertainty in large drop measurement. Longer integration times can be used for the collection of larger disdrometer samples. However, integration periods must be consistent with a radar resolution volume (RRV) and the temporal and spatial scales of the physical processes affecting the DSD therein. Multiple co-located disdrometers can be combined into a network to increase the sample size within a RRV. However, over a reasonable integration period, a single disdrometer sample volume is many orders of magnitudes less than a RRV so it is not practical to devise a network of disdrometers that has an equivalent volume to a typical RRV. Since knowledge of DSD heterogeneity and large drop occurrence in time and space is lacking, the specific accuracy or even general representativeness of disdrometer based D(sub max) and large drop concentration estimates within a RRV are currently unknown. To address this complex issue, we begin with a simpler question. Is the frequency of

  17. Squaring a Circular Segment

    ERIC Educational Resources Information Center

    Gordon, Russell

    2008-01-01

    Consider a circular segment (the smaller portion of a circle cut off by one of its chords) with chord length c and height h (the greatest distance from a point on the arc of the circle to the chord). Is there a simple formula involving c and h that can be used to closely approximate the area of this circular segment? Ancient Chinese and Egyptian…

  18. Background Noises Versus Intraseasonal Variation Signals: Small vs. Large Convective Cloud Objects From CERES Aqua Observations

    NASA Technical Reports Server (NTRS)

    Xu, Kuan-Man

    2015-01-01

    During inactive phases of Madden-Julian Oscillation (MJO), there are plenty of deep but small convective systems and far fewer deep and large ones. During active phases of MJO, a manifestation of an increase in the occurrence of large and deep cloud clusters results from an amplification of large-scale motions by stronger convective heating. This study is designed to quantitatively examine the roles of small and large cloud clusters during the MJO life cycle. We analyze the cloud object data from Aqua CERES (Clouds and the Earth's Radiant Energy System) observations between July 2006 and June 2010 for tropical deep convective (DC) and cirrostratus (CS) cloud object types according to the real-time multivariate MJO index, which assigns the tropics to one of the eight MJO phases each day. The cloud object is a contiguous region of the earth with a single dominant cloud-system type. The criteria for defining these cloud types are overcast footprints and cloud top pressures less than 400 hPa, but DC has higher cloud optical depths (=10) than those of CS (<10). The size distributions, defined as the footprint numbers as a function of cloud object diameters, for particular MJO phases depart greatly from the combined (8-phase) distribution at large cloud-object diameters due to the reduced/increased numbers of cloud objects related to changes in the large-scale environments. The medium diameter corresponding to the combined distribution is determined and used to partition all cloud objects into "small" and "large" groups of a particular phase. The two groups corresponding to the combined distribution have nearly equal numbers of footprints. The medium diameters are 502 km for DC and 310 km for cirrostratus. The range of the variation between two extreme phases (typically, the most active and depressed phases) for the small group is 6-11% in terms of the numbers of cloud objects and the total footprint numbers. The corresponding range for the large group is 19-44%. In

  19. Small vs. Large Convective Cloud Objects from CERES Aqua Observations: Where are the Intraseasonal Variation Signals?

    NASA Technical Reports Server (NTRS)

    Xu, Kuan-Man

    2016-01-01

    During inactive phases of Madden-Julian oscillation (MJO), there are plenty of deep but small convective systems and far fewer deep and large ones. During active phases of MJO, a manifestation of an increase in the occurrence of large and deep cloud clusters results from an amplification of large-scale motions by stronger convective heating. This study is designed to quantitatively examine the roles of small and large cloud clusters during the MJO life cycle. We analyze the cloud object data from Aqua CERES observations for tropical deep convective (DC) and cirrostratus (CS) cloud object types according to the real-time multivariate MJO index. The cloud object is a contiguous region of the earth with a single dominant cloud-system type. The size distributions, defined as the footprint numbers as a function of cloud object diameters, for particular MJO phases depart greatly from the combined (8-phase) distribution at large cloud-object diameters due to the reduced/increased numbers of cloud objects related to changes in the large-scale environments. The medium diameter corresponding to the combined distribution is determined and used to partition all cloud objects into "small" and "large" groups of a particular phase. The two groups corresponding to the combined distribution have nearly equal numbers of footprints. The medium diameters are 502 km for DC and 310 km for cirrostratus. The range of the variation between two extreme phases (typically, the most active and depressed phases) for the small group is 6-11% in terms of the numbers of cloud objects and the total footprint numbers. The corresponding range for the large group is 19-44%. In terms of the probability density functions of radiative and cloud physical properties, there are virtually no differences between the MJO phases for the small group, but there are significant differences for the large groups for both DC and CS types. These results suggest that the intreseasonal variation signals reside at the

  20. Simultaneous Solar Maximum Mission (SMM) and very large array observations of solar active regions

    NASA Technical Reports Server (NTRS)

    Lang, K. R.

    1986-01-01

    The research deals mainly with Very Large Array and Solar Maximum Mission observations of the ubiquitous coronal loops that dominate the structure of the low corona. As illustrated, the observations of thermal cyclotron lines at microwave wavelengths provide a powerful new method of accurately specifying the coronal magnetic field strength. Processes are delineated that trigger solar eruptions from coronal loops, including preburst heating and the magnetic interaction of coronal loops. Evidence for coherent burst mechanisms is provided for both the Sun and nearby stars, while other observations suggest the presence of currents that may amplify the coronal magnetic field to unexpectedly high levels. The existence is reported of a new class of compact, variable moving sources in regions of apparently weak photospheric field.

  1. Large-scale motions of the tropics in observations and theory

    NASA Technical Reports Server (NTRS)

    Paegle, J.; Paegle, J. N.; Lewis, F. P.

    1983-01-01

    Charney (1963) characterized the tropical atmosphere in terms of a superposition of large regions of nearly nondivergent circulations containing local subdomains, or 'fissures', of active convection and latent heating. Tropical wave evolution is then appropriately treated in terms of quasi-rotational waves, to the extent that the divergent contribution is small. An attempt is presently made to interpret recent tropical analyses in the aforementioned terms, suggesting extensions of the simplest quasi-rotational model capable of reconciling observations and theory. First GARP Global Experiment (FGGE) observations suggest that strongly divergent local tropical circulations are forced by latent heating and produce important direct modifications of the total wind field; after describing the extent to which the resulting field consists of divergent and rotational components in different analyses of the FGGE data, independent supporting documentation of the results in terms of heating estimates and rainfall observations are given.

  2. Observed large-scale structures and diabatic heating and drying profiles during TWP-ICE

    SciTech Connect

    Xie, Shaocheng; Hume, Timothy; Jakob, Christian; Klein, Stephen A.; McCoy, Renata B.; Zhang, Minghua

    2010-01-01

    This study documents the characteristics of the large-scale structures and diabatic heating and drying profiles observed during the Tropical Warm Pool–International Cloud Experiment (TWP-ICE), which was conducted in January–February 2006 in Darwin during the northern Australian monsoon season. The examined profiles exhibit significant variations between four distinct synoptic regimes that were observed during the experiment. The active monsoon period is characterized by strong upward motion and large advective cooling and moistening throughout the entire troposphere, while the suppressed and clear periods are dominated by moderate midlevel subsidence and significant low- to midlevel drying through horizontal advection. The midlevel subsidence and horizontal dry advection are largely responsible for the dry midtroposphere observed during the suppressed period and limit the growth of clouds to low levels. During the break period, upward motion and advective cooling and moistening located primarily at midlevels dominate together with weak advective warming and drying (mainly from horizontal advection) at low levels. The variations of the diabatic heating and drying profiles with the different regimes are closely associated with differences in the large-scale structures, cloud types, and rainfall rates between the regimes. Strong diabatic heating and drying are seen throughout the troposphere during the active monsoon period while they are moderate and only occur above 700 hPa during the break period. The diabatic heating and drying tend to have their maxima at low levels during the suppressed periods. Furthermore, the diurnal variations of these structures between monsoon systems, continental/coastal, and tropical inland-initiated convective systems are also examined.

  3. Observed large-scale structures and diabatic heating and drying profiles during TWP-ICE

    DOE PAGES

    Xie, Shaocheng; Hume, Timothy; Jakob, Christian; ...

    2010-01-01

    This study documents the characteristics of the large-scale structures and diabatic heating and drying profiles observed during the Tropical Warm Pool–International Cloud Experiment (TWP-ICE), which was conducted in January–February 2006 in Darwin during the northern Australian monsoon season. The examined profiles exhibit significant variations between four distinct synoptic regimes that were observed during the experiment. The active monsoon period is characterized by strong upward motion and large advective cooling and moistening throughout the entire troposphere, while the suppressed and clear periods are dominated by moderate midlevel subsidence and significant low- to midlevel drying through horizontal advection. The midlevel subsidence andmore » horizontal dry advection are largely responsible for the dry midtroposphere observed during the suppressed period and limit the growth of clouds to low levels. During the break period, upward motion and advective cooling and moistening located primarily at midlevels dominate together with weak advective warming and drying (mainly from horizontal advection) at low levels. The variations of the diabatic heating and drying profiles with the different regimes are closely associated with differences in the large-scale structures, cloud types, and rainfall rates between the regimes. Strong diabatic heating and drying are seen throughout the troposphere during the active monsoon period while they are moderate and only occur above 700 hPa during the break period. The diabatic heating and drying tend to have their maxima at low levels during the suppressed periods. Furthermore, the diurnal variations of these structures between monsoon systems, continental/coastal, and tropical inland-initiated convective systems are also examined.« less

  4. Large-Scale Overlays and Trends: Visually Mining, Panning and Zooming the Observable Universe.

    PubMed

    Luciani, Timothy Basil; Cherinka, Brian; Oliphant, Daniel; Myers, Sean; Wood-Vasey, W Michael; Labrinidis, Alexandros; Marai, G Elisabeta

    2014-07-01

    We introduce a web-based computing infrastructure to assist the visual integration, mining and interactive navigation of large-scale astronomy observations. Following an analysis of the application domain, we design a client-server architecture to fetch distributed image data and to partition local data into a spatial index structure that allows prefix-matching of spatial objects. In conjunction with hardware-accelerated pixel-based overlays and an online cross-registration pipeline, this approach allows the fetching, displaying, panning and zooming of gigabit panoramas of the sky in real time. To further facilitate the integration and mining of spatial and non-spatial data, we introduce interactive trend images-compact visual representations for identifying outlier objects and for studying trends within large collections of spatial objects of a given class. In a demonstration, images from three sky surveys (SDSS, FIRST and simulated LSST results) are cross-registered and integrated as overlays, allowing cross-spectrum analysis of astronomy observations. Trend images are interactively generated from catalog data and used to visually mine astronomy observations of similar type. The front-end of the infrastructure uses the web technologies WebGL and HTML5 to enable cross-platform, web-based functionality. Our approach attains interactive rendering framerates; its power and flexibility enables it to serve the needs of the astronomy community. Evaluation on three case studies, as well as feedback from domain experts emphasize the benefits of this visual approach to the observational astronomy field; and its potential benefits to large scale geospatial visualization in general.

  5. Large Deployable Reflector Technologies for Future European Telecom and Earth Observation Missions

    NASA Astrophysics Data System (ADS)

    Ihle, A.; Breunig, E.; Dadashvili, L.; Migliorelli, M.; Scialino, L.; van't Klosters, K.; Santiago-Prowald, J.

    2012-07-01

    This paper presents requirements, analysis and design results for European large deployable reflectors (LDR) for space applications. For telecommunications, the foreseeable use of large reflectors is associated to the continuous demand for improved performance of mobile services. On the other hand, several earth observation (EO) missions can be identified carrying either active or passive remote sensing instruments (or both), in which a large effective aperture is needed e.g. BIOMASS. From the European point of view there is a total dependence of USA industry as such LDRs are not available from European suppliers. The RESTEO study is part of a number of ESA led activities to facilitate European LDR development. This paper is focused on the structural-mechanical aspects of this study. We identify the general requirements for LDRs with special emphasis on launcher accommodation for EO mission. In the next step, optimal concepts for the LDR structure and the RF-Surface are reviewed. Regarding the RF surface, both, a knitted metal mesh and a shell membrane based on carbon fibre reinforced silicon (CFRS) are considered. In terms of the backing structure, the peripheral ring concept is identified as most promising and a large number of options for the deployment kinematics are discussed. Of those, pantographic kinematics and a conical peripheral ring are selected. A preliminary design for these two most promising LDR concepts is performed which includes static, modal and kinematic simulation and also techniques to generate the reflector nets.

  6. Large discrete jumps observed in the transition between Chern states in a ferromagnetic topological insulator.

    PubMed

    Liu, Minhao; Wang, Wudi; Richardella, Anthony R; Kandala, Abhinav; Li, Jian; Yazdani, Ali; Samarth, Nitin; Ong, N Phuan

    2016-07-01

    A striking prediction in topological insulators is the appearance of the quantized Hall resistance when the surface states are magnetized. The surface Dirac states become gapped everywhere on the surface, but chiral edge states remain on the edges. In an applied current, the edge states produce a quantized Hall resistance that equals the Chern number C = ±1 (in natural units), even in zero magnetic field. This quantum anomalous Hall effect was observed by Chang et al. With reversal of the magnetic field, the system is trapped in a metastable state because of magnetic anisotropy. We investigate how the system escapes the metastable state at low temperatures (10 to 200 mK). When the dissipation (measured by the longitudinal resistance) is ultralow, we find that the system escapes by making a few very rapid transitions, as detected by large jumps in the Hall and longitudinal resistances. Using the field at which the initial jump occurs to estimate the escape rate, we find that raising the temperature strongly suppresses the rate. From a detailed map of the resistance versus gate voltage and temperature, we show that dissipation strongly affects the escape rate. We compare the observations with dissipative quantum tunneling predictions. In the ultralow dissipation regime, two temperature scales (T 1 ~ 70 mK and T 2 ~ 145 mK) exist, between which jumps can be observed. The jumps display a spatial correlation that extends over a large fraction of the sample.

  7. Large discrete jumps observed in the transition between Chern states in a ferromagnetic topological insulator

    PubMed Central

    Liu, Minhao; Wang, Wudi; Richardella, Anthony R.; Kandala, Abhinav; Li, Jian; Yazdani, Ali; Samarth, Nitin; Ong, N. Phuan

    2016-01-01

    A striking prediction in topological insulators is the appearance of the quantized Hall resistance when the surface states are magnetized. The surface Dirac states become gapped everywhere on the surface, but chiral edge states remain on the edges. In an applied current, the edge states produce a quantized Hall resistance that equals the Chern number C = ±1 (in natural units), even in zero magnetic field. This quantum anomalous Hall effect was observed by Chang et al. With reversal of the magnetic field, the system is trapped in a metastable state because of magnetic anisotropy. We investigate how the system escapes the metastable state at low temperatures (10 to 200 mK). When the dissipation (measured by the longitudinal resistance) is ultralow, we find that the system escapes by making a few very rapid transitions, as detected by large jumps in the Hall and longitudinal resistances. Using the field at which the initial jump occurs to estimate the escape rate, we find that raising the temperature strongly suppresses the rate. From a detailed map of the resistance versus gate voltage and temperature, we show that dissipation strongly affects the escape rate. We compare the observations with dissipative quantum tunneling predictions. In the ultralow dissipation regime, two temperature scales (T1 ~ 70 mK and T2 ~ 145 mK) exist, between which jumps can be observed. The jumps display a spatial correlation that extends over a large fraction of the sample. PMID:27482539

  8. High-resolution Observations of a Large Fan-shaped Surge

    NASA Astrophysics Data System (ADS)

    Li, Zhen; Fang, Cheng; Guo, Yang; Chen, P. F.; Zou, Peng; Cao, Wenda

    2016-08-01

    We present high-resolution observations of a large fan-shaped surge, which was observed on 2013 June 5 with the current largest solar telescope, the 1.6 m New Solar Telescope (NST), at the Big Bear Solar Observatory. The observations are made at TiO, Hα, and 10830 Å wavebands with a spatial resolution better than 0\\buildrel{\\prime\\prime}\\over{.} 1 and a full-run cadence of ˜30 s. The fan-shaped surge consists of many small-scale threads with a typical width of 100 km and a length of up to 200 Mm at the maximum. The threads come from material ejections, which start with a velocity of several km s-1, and then accelerate up to 60-80 km s-1 over six to seven minutes with an acceleration of up to 0.2-0.3 km s-2. The threads can be observed in the Hα band and in SDO/AIA 171 Å images as absorbed objects, implying that they are cool material ejections. The surge is ejected along open magnetic field lines in the extrapolated non-linear force-free field, which might actually be a part of a large-scale magnetic loop stretching back to the solar surface. After 10-20 minutes, the ejections gradually decay and the surge eventually vanishes. The total lifetime is about 35 minutes. The Hα brightening at the root of the fan-shaped surge implies that there is heating in the chromosphere, which could be produced by low-atmosphere interchange magnetic reconnection. Our observation provides evidence of the reconnection model for the fan-shaped surges, which was proposed by Jiang et al.

  9. Large-Amplitude Oscillation of an Erupting Filament as Seen in EUV, Hα, and Microwave Observations

    NASA Astrophysics Data System (ADS)

    Isobe, H.; Tripathi, D.; Asai, A.; Jain, R.

    2007-11-01

    We present multiwavelength observations of a large-amplitude oscillation of a polar-crown filament on 15 October 2002, which has been reported by Isobe and Tripathi ( Astron. Astrophys. 449, L17, 2006). The oscillation occurred during the slow rise (≈1 km s-1) of the filament. It completed three cycles before sudden acceleration and eruption. The oscillation and following eruption were clearly seen in observations recorded by the Extreme-Ultraviolet Imaging Telescope (EIT) onboard the Solar and Heliospheric Observatory (SOHO). The oscillation was seen only in a part of the filament, and it appears to be a standing oscillation rather than a propagating wave. The amplitudes of velocity and spatial displacement of the oscillation in the plane of the sky were about 5 km s-1 and 15 000 km, respectively. The period of oscillation was about two hours and did not change significantly during the oscillation. The oscillation was also observed in Hα by the Flare Monitoring Telescope at the Hida Observatory. We determine the three-dimensional motion of the oscillation from the Hα wing images. The maximum line-of-sight velocity was estimated to be a few tens of kilometers per second, although the uncertainty is large owing to the lack of line-profile information. Furthermore, we also identified the spatial displacement of the oscillation in 17-GHz microwave images from Nobeyama Radio Heliograph (NoRH). The filament oscillation seems to be triggered by magnetic reconnection between a filament barb and nearby emerging magnetic flux as was evident from the MDI magnetogram observations. No flare was observed to be associated with the onset of the oscillation. We also discuss possible implications of the oscillation as a diagnostic tool for the eruption mechanisms. We suggest that in the early phase of eruption a part of the filament lost its equilibrium first, while the remaining part was still in an equilibrium and oscillated.

  10. EXPANDED VERY LARGE ARRAY OBSERVATIONS OF THE BARNARD 5 STAR-FORMING CORE: EMBEDDED FILAMENTS REVEALED

    SciTech Connect

    Pineda, Jaime E.; Longmore, Steven; Goodman, Alyssa A.; Arce, Hector G.; Caselli, Paola; Corder, Stuartt

    2011-09-20

    We present {approx}6.'5 x 8' Expanded Very Large Array (EVLA) mosaic observations of the NH{sub 3} (1,1) emission in the Barnard 5 region in Perseus, with an angular resolution of 6''. This map covers the coherent region, where the dense gas presents subsonic non-thermal motions (as seen from single dish observations with the Green Bank Telescope, GBT). The combined EVLA and GBT observations reveal, for the first time, a striking filamentary structure (20'' wide or 5000 AU at the distance of Perseus) in this low-mass star-forming region. The integrated intensity profile of this structure is consistent with models of an isothermal filament in hydrostatic equilibrium. The observed separation between the B5-IRS1 young stellar object (YSO), in the central region of the core, and the northern starless condensation matches the Jeans length of the dense gas. This suggests that the dense gas in the coherent region is fragmenting. The observed region displays a narrow velocity dispersion, where most of the gas shows evidence for subsonic turbulence and where little spatial variations are present. It is only close to the YSO where an increase in the velocity dispersion is found, but still displaying subsonic non-thermal motions.

  11. Catching the `Bullet' with Parkes: A Pilot Study for large-scale galaxy cluster observations

    NASA Astrophysics Data System (ADS)

    Malu, Siddharth; Carretti, Ettore; Subrahmanyan, Ravi; Wieringa, Mark; Narasimha, D.

    2011-10-01

    We propose to observe the ‘bullet’ cluster of galaxies - 1E 0657-56 - which consists of two sub-clusters in the process of merging and manifests relatively cold clouds plowing through hot intra-cluster gas, using the Parkes Telescope at 18 GHz. We aim to image the sub-structure in the gas pressure distribution via the inverse-Compton scattering of cosmic microwave background photons (the Sunyaev-Zeldovich Effect; SZE). The observations constitute a probe of fine structure in the physical state of the intra-cluster gas, the physics of propagation and stability of cold fronts in cluster mergers and a measure of cluster magnetic field. The small scale structure has been observed with the ATCA already (Wilson et al. MNRAS 2011; Malu et al. arXiv:1005.1394), but the large scale emission, essential to recover the entire amount of the SZ effects, is missed by those observations because of lack of sensitivity on scales larger than the primary beam. Combining with single dish observations is thus essential to derive cluster physical quantities (like electron density and gas temperature) and we propose here to conduct them with the Parkes telescope.

  12. Observation of Stable Low Surface Resistance in Large-Grain Niobium SRF Cavities

    SciTech Connect

    Geng, Rongli; Huang, Shichun

    2016-05-01

    Low surface resistance, or high unloaded quality factor (Q0), superconducting radio frequency (SRF) cavities are being pursued actively nowadays as their application in large-scale CW SRF accelerators can save capital and operational cost in cryogenics. There are different options in realization of such cavities. One of them is the large-grain (LG) niobium cavity. In this contribution, we present new experimental results in evaluation of LG niobium cavities cooled down in the presence of an external magnetic field. High Q0 values are achieved even with an ambient magnetic field of up to 100 mG. More over, it is observed that these high Q0 values are super-robust against repeated quench, literally not affected at all after the cavity being deliberately quenched for hundreds of times in the presence of an ambient magnetic field of up to 200 mG.

  13. Observing trans-Planckian ripples in the primordial power spectrum with future large scale structure probes

    SciTech Connect

    Hamann, Jan; Hannestad, Steen; Sloth, Martin S; Wong, Yvonne Y Y E-mail: sth@phys.au.dk E-mail: ywong@mppmu.mpg.de

    2008-09-15

    We revisit the issue of ripples in the primordial power spectra caused by trans-Planckian physics, and the potential for their detection by future cosmological probes. We find that for reasonably large values of the first slow-roll parameter {epsilon} ({approx}>0.001), a positive detection of trans-Planckian ripples can be made even if the amplitude is as low as 10{sup -4}. Data from the Large Synoptic Survey Telescope (LSST) and the proposed future 21 cm survey with the Fast Fourier Transform Telescope (FFTT) will be particularly useful in this regard. If the scale of inflation is close to its present upper bound, a scale of new physics as high as {approx}0.2 M{sub P} could lead to observable signatures.

  14. Large Binocular Telescope Observations of Europa Occulting Io's Volcanoes at 4.8 μm

    NASA Astrophysics Data System (ADS)

    Skrutskie, Michael F.; Conrad, Albert; Resnick, Aaron; Leisenring, Jarron; Hinz, Phil; de Pater, Imke; de Kleer, Katherine; Spencer, John; Skemer, Andrew; Woodward, Charles E.; Davies, Ashley Gerard; Defrére, Denis

    2015-11-01

    On 8 March 2015 Europa passed nearly centrally in front of Io. The Large Binocular Telescope observed this event in dual-aperture AO-corrected Fizeau interferometric imaging mode using the mid-infrared imager LMIRcam operating behind the Large Binocular Telescope Interferometer (LBTI) at a broadband wavelength of 4.8 μm (M-band). Occultation light curves generated from frames recorded every 123 milliseconds show that both Loki and Pele/Pillan were well resolved. Europa's center shifted by 2 kilometers relative to Io from frame-to-frame. The derived light curve for Loki is consistent with the double-lobed structure reported by Conrad et al. (2015) using direct interferometric imaging with LBTI.

  15. Strong circular photogalvanic effect in ZnO epitaxial films

    SciTech Connect

    Zhang, Q.; Wang, X. Q.; Yin, C. M.; Shen, B.; Chen, Y. H.; Chang, K.; Ge, W. K.

    2011-12-23

    A strong circular photogalvanic effect (CPGE) in ZnO epitaxial films was reported under interband excitation. It was observed that CPGE current is as large as 100 nA/W in ZnO, which is about one order in magnitude higher than that in InN film while the CPGE currents in GaN films are not detectable. The possible reasons for the above observations are the strong spin orbit coupling in ZnO or the inversed valence band structure of ZnO.

  16. Strong circular photogalvanic effect in ZnO epitaxial films

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Wang, X. Q.; Yin, C. M.; Shen, B.; Chen, Y. H.; Chang, K.; Ge, W. K.

    2011-12-01

    A strong circular photogalvanic effect (CPGE) in ZnO epitaxial films was reported under interband excitation. It was observed that CPGE current is as large as 100 nA/W in ZnO, which is about one order in magnitude higher than that in InN film while the CPGE currents in GaN films are not detectable. The possible reasons for the above observations are the strong spin orbit coupling in ZnO or the inversed valence band structure of ZnO.

  17. Strong circular photogalvanic effect in ZnO epitaxial films

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Wang, X. Q.; Yin, C. M.; Xu, F. J.; Tang, N.; Shen, B.; Chen, Y. H.; Chang, K.; Ge, W. K.; Ishitani, Y.; Yoshikawa, A.

    2010-07-01

    We report a strong circular photogalvanic effect (CPGE) in ZnO epitaxial films under interband excitation. It is observed that CPGE current is as large as 100 nA/W in ZnO, which is about one order in magnitude higher than that in InN film while the CPGE currents in GaN films are not detectable. The possible reasons for the above observations are the strong spin orbit coupling in ZnO or the inversed valence band structure of ZnO.

  18. Sedimentary environments and preservation biases limit sulfur isotope fractionation observed in pyrite, despite large microbial fractionations

    NASA Astrophysics Data System (ADS)

    Halevy, I.; Wing, B. A.; Wenk, C.; Guimond, C.

    2015-12-01

    Microbial S isotope fractionations close to the thermodynamic fractionation between sulfate and sulfide (~70‰) are encountered only at the slowest rates of sulfate reduction in laboratory cultures. In turn, the slowest laboratory reduction rates overlap with only the highest values of cell-specific sulfate reduction rates measured in marine sediments. This chain-of-logic implies that sulfate-reducing microbes in the marine sedimentary biosphere fractionate S isotopes at magnitudes close to the thermodynamic limit. Recent observations from sulfate-poor environments indicate that fractionations are large even at micromolar sulfate concentrations, in agreement with model predictions of near-thermodynamic S isotope fractionation at these sulfate concentrations as long as cell-specific sulfate reduction rates are low. Despite the expectation of large microbial fractionations, pyrite in both modern marine sediments and Phanerozoic sedimentary rocks records apparent fractionations ranging from 0 to more than 70‰. We suggest that the observed range of modern marine and geologic apparent fractionations recorded in pyrite does not reflect variability in intrinsic microbial behavior, but an early diagenetic modulation of large microbial fractionations, which are pinned to the thermodynamic limit by the low natural rates of sulfate reduction. With a diagenetic model developed in this study, we show that the entire range of apparent fractionations is possible with microbial fractionations at the thermodynamic limit. Apparent fractionations depend on a variety of physical parameters of the sedimentary environment like sedimentation rate, porosity, and organic matter content, most of which correlate with water depth. These findings, in combination with knowledge about the preservation potential of sediments deposited at different depths, make predictions for the observed geologic range of apparent fractionations, and ways in which it differs from the range in modern marine

  19. Digitalizing the Circular Economy

    NASA Astrophysics Data System (ADS)

    Reuter, Markus A.

    2016-12-01

    Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure. This will be illustrated through the following: (1) System optimization models for multimetal metallurgical processing. These map large-scale m-IoT systems linked to computer-aided design tools of the original equipment manufacturers and then establish a recycling index through the quantification of RE. (2) Reactor optimization and industrial system solutions to realize the "CE (within a) Corporation—CEC," realizing the CE of society. (3) Real-time measurement of ore and scrap properties in intelligent plant structures, linked to the modeling, simulation, and optimization of industrial extractive process

  20. ALIS (Auroral Large Imaging System) used for optical observations of the meteor impact process

    NASA Astrophysics Data System (ADS)

    Brändström, U.; Gustavsson, B.; Steen, A.; Pellinen-Wannberg, Asta

    2001-11-01

    This paper outlines a possibly new use of the Auroral Large Imaging System (ALIS) for studies of differential ablation phenomena in meteor trails. By simultaneous imaging from up to six stations, the altitude distribution of the meteor trails could be triangulated, while some stations simultaneously image the trails in for example the sodium (5893 Å) and calcium (4227 Å) lines. ALIS was primarily designed for auroral studies, but has also been used for studies of heater-induced airglow, polar stratospheric clouds as well as other phenomena. The system consits of six unmanned remote-controlled observation stations located in northern Sweden.

  1. IRAS observations of a large circumstellar dust shell around W Hydrae

    NASA Technical Reports Server (NTRS)

    Hawkins, G. W.

    1990-01-01

    IRAS observations at 60 and 100 microns reveal a large 30-40-arcmin (about 1-pc) diameter dust shell centered on the oxygen-rich red giant W Hya. Except for SNRs, this is the largest mass-loss envelope, in apparent diameter, known around any evolved star, including PN. W Hya's radiation field, stronger than the interstellar radiation field in the outer envelope, is sufficient to heat dust grains with IR emissivity proportional to lambda exp -1.2 to temperatures of about 40 K implied by the ratio of intensities at 60 and 100 microns.

  2. Observation of quantum particles on a large space-time scale

    NASA Astrophysics Data System (ADS)

    Landau, L. J.

    1994-10-01

    A quantum particle observed on a sufficiently large space-time scale can be described by means of classical particle trajectories. The joint distribution for large-scale multiple-time position and momentum measurements on a nonrelativistic quantum particle moving freely in R v is given by straight-line trajectories with probabilities determined by the initial momentum-space wavefunction. For large-scale toroidal and rectangular regions the trajectories are geodesics. In a uniform gravitational field the trajectories are parabolas. A quantum counting process on free particles is also considered and shown to converge in the large-space-time limit to a classical counting process for particles with straight-line trajectories. If the quantum particle interacts weakly with its environment, the classical particle trajectories may undergo random jumps. In the random potential model considered here, the quantum particle evolves according to a reversible unitary one-parameter group describing elastic scattering off static randomly distributed impurities (a quantum Lorentz gas). In the large-space-time weak-coupling limit a classical stochastic process is obtained with probability one and describes a classical particle moving with constant speed in straight lines between random jumps in direction. The process depends only on the ensemble value of the covariance of the random field and not on the sample field. The probability density in phase space associated with the classical stochastic process satisfies the linear Boltzmann equation for the classical Lorentz gas, which, in the limit h→0, goes over to the linear Landau equation. Our study of the quantum Lorentz gas is based on a perturbative expansion and, as in other studies of this system, the series can be controlled only for small values of the rescaled time and for Gaussian random fields. The discussion of classical particle trajectories for nonrelativistic particles on a macroscopic spacetime scale applies also to

  3. Circular free-electron laser

    DOEpatents

    Brau, Charles A.; Kurnit, Norman A.; Cooper, Richard K.

    1984-01-01

    A high efficiency, free electron laser utilizing a circular relativistic electron beam accelerator and a circular whispering mode optical waveguide for guiding optical energy in a circular path in the circular relativistic electron beam accelerator such that the circular relativistic electron beam and the optical energy are spatially contiguous in a resonant condition for free electron laser operation. Both a betatron and synchrotron are disclosed for use in the present invention. A free electron laser wiggler is disposed around the circular relativistic electron beam accelerator for generating a periodic magnetic field to transform energy from the circular relativistic electron beam to optical energy.

  4. The deterioration of Circular Mausoleum, Roman Necropolis of Carmona, Spain.

    PubMed

    Cañaveras, Juan C; Fernandez-Cortes, Angel; Elez, Javier; Cuezva, Soledad; Jurado, Valme; Miller, Ana Zelia; Rogerio-Candelera, Miguel A; Benavente, David; Hernandez-Marine, Mariona; Saiz-Jimenez, Cesareo; Sanchez-Moral, Sergio

    2015-06-15

    The Circular Mausoleum tomb in the Roman Necropolis of Carmona was carved on a calcarenite sequence in an ancient quarry located in the town of Carmona, Southern Spain. This rock-cut tomb, representative of Roman burial practices, currently suffers from serious deterioration. A detailed survey over several years permitted the identification of the main tomb's pathologies and damaging processes, which include loss of material (scaling, flaking, granular disintegration), surface modifications (efflorescences, crusts and deposits) and extensive biological colonization. The results obtained in this study indicated that anthropogenic changes were largely responsible and enhanced the main alteration mechanisms observed in the Circular Mausoleum. Based on the deterioration diagnosis, effective corrective actions were proposed. This study shows that any conservative intervention in the interior of the tomb should be preceded by accurate in situ measurements and laboratory analyses to ascribe the source of the deterioration damages and thus designing effective treatments.

  5. Towards future circular colliders

    NASA Astrophysics Data System (ADS)

    Benedikt, Michael; Zimmermann, Frank

    2016-09-01

    The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) presently provides proton-proton collisions at a center-of-mass (c.m.) energy of 13 TeV. The LHC design was started more than 30 years ago, and its physics program will extend through the second half of the 2030's. The global Future Circular Collider (FCC) study is now preparing for a post-LHC project. The FCC study focuses on the design of a 100-TeV hadron collider (FCC-hh) in a new ˜100 km tunnel. It also includes the design of a high-luminosity electron-positron collider (FCCee) as a potential intermediate step, and a lepton-hadron collider option (FCC-he). The scope of the FCC study comprises accelerators, technology, infrastructure, detectors, physics, concepts for worldwide data services, international governance models, and implementation scenarios. Among the FCC core technologies figure 16-T dipole magnets, based on Nb3 S n superconductor, for the FCC-hh hadron collider, and a highly-efficient superconducting radiofrequency system for the FCC-ee lepton collider. Following the FCC concept, the Institute of High Energy Physics (IHEP) in Beijing has initiated a parallel design study for an e + e - Higgs factory in China (CEPC), which is to be succeeded by a high-energy hadron collider (SPPC). At present a tunnel circumference of 54 km and a hadron collider c.m. energy of about 70 TeV are being considered. After a brief look at the LHC, this article reports the motivation and the present status of the FCC study, some of the primary design challenges and R&D subjects, as well as the emerging global collaboration.

  6. Observation of high-spin bands with large moments of inertia in 124Xe

    NASA Astrophysics Data System (ADS)

    Nag, Somnath; Singh, A. K.; Hagemann, G. B.; Sletten, G.; Herskind, B.; Døssing, T.; Ragnarsson, I.; Hübel, H.; Bürger, A.; Chmel, S.; Wilson, A. N.; Rogers, J.; Carpenter, M. P.; Janssens, R. V. F.; Khoo, T. L.; Kondev, F. G.; Lauritsen, T.; Zhu, S.; Korichi, A.; Stefanova, E. A.; Fallon, P.; Nyakó, B. M.; Timár, J.; Juhász, K.

    2016-09-01

    High-spin states in 124Xe have been populated using the 80Se(48Ca,4 n ) reaction at a beam energy of 207 MeV and high-multiplicity, γ -ray coincidence events were measured using the Gammasphere spectrometer. Six high-spin bands with large moments of inertia, similar to those observed in neighboring nuclei, have been observed. The experimental results are compared with calculations within the framework of the cranked Nilsson-Strutinsky model. It is suggested that the configurations of the bands involve excitations of protons across the Z =50 shell gap coupled to neutrons within the N =50 -82 shell or excited across the N =82 shell closure.

  7. Interference data correction methods for lunar observation with a large-aperture static imaging spectrometer.

    PubMed

    Zhang, Geng; Wang, Shuang; Li, Libo; Hu, Xiuqing; Hu, Bingliang

    2016-11-01

    The lunar spectrum has been used in radiometric calibration and sensor stability monitoring for spaceborne optical sensors. A ground-based large-aperture static image spectrometer (LASIS) can be used to acquire the lunar spectral image for lunar radiance model improvement when the moon orbits over its viewing field. The lunar orbiting behavior is not consistent with the desired scanning speed and direction of LASIS. To correctly extract interferograms from the obtained data, a translation correction method based on image correlation is proposed. This method registers the frames to a reference frame to reduce accumulative errors. Furthermore, we propose a circle-matching-based approach to achieve even higher accuracy during observation of the full moon. To demonstrate the effectiveness of our approaches, experiments are run on true lunar observation data. The results show that the proposed approaches outperform the state-of-the-art methods.

  8. Fermi Large Area Telescope Observations of the Cosmic-Ray Induced

    SciTech Connect

    Abdo, A.

    2012-02-29

    We report on measurements of the cosmic-ray induced {gamma}-ray emission of Earth's atmosphere by the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope. The LAT has observed the Earth during its commissioning phase and with a dedicated Earth-limb following observation in September 2008. These measurements yielded {approx} 6.4 x 10{sup 6} photons with energies > 100 MeV and {approx} 250 hours total livetime for the highest quality data selection. This allows the study of the spatial and spectral distributions of these photons with unprecedented detail. The spectrum of the emission - often referred to as Earth albedo gamma-ray emission - has a power-law shape up to 500 GeV with spectral index {Lambda} = 2.79 {+-} 0.06.

  9. Large Amplitude Whistlers in the Magnetosphere Observed with Wind-Waves

    NASA Technical Reports Server (NTRS)

    Kellogg, P. J.; Cattell, C. A.; Goetz, K.; Monson, S. J.; Wilson, L. B., III

    2011-01-01

    We describe the results of a statistical survey of Wind-Waves data motivated by the recent STEREO/Waves discovery of large-amplitude whistlers in the inner magnetosphere. Although Wind was primarily intended to monitor the solar wind, the spacecraft spent 47 h inside 5 R(sub E) and 431 h inside 10 R(sub E) during the 8 years (1994-2002) that it orbited the Earth. Five episodes were found when whistlers had amplitudes comparable to those of Cattell et al. (2008), i.e., electric fields of 100 m V/m or greater. The whistlers usually occurred near the plasmapause. The observations are generally consistent with the whistlers observed by STEREO. In contrast with STEREO, Wind-Waves had a search coil, so magnetic measurements are available, enabling determination of the wave vector without a model. Eleven whistler events with useable magnetic measurements were found. The wave vectors of these are distributed around the magnetic field direction with angles from 4 to 48deg. Approximations to observed electron distribution functions show a Kennel-Petschek instability which, however, does not seem to produce the observed whistlers. One Wind episode was sampled at 120,000 samples/s, and these events showed a signature that is interpreted as trapping of electrons in the electrostatic potential of an oblique whistler. Similar waveforms are found in the STEREO data. In addition to the whistler waves, large amplitude, short duration solitary waves (up to 100 mV/m), presumed to be electron holes, occur in these passes, primarily on plasma sheet field lines mapping to the auroral zone.

  10. Compact waveguide circular polarizer

    SciTech Connect

    Tantawi, Sami G.

    2016-08-16

    A multi-port waveguide is provided having a rectangular waveguide that includes a Y-shape structure with first top arm having a first rectangular waveguide port, a second top arm with second rectangular waveguide port, and a base arm with a third rectangular waveguide port for supporting a TE.sub.10 mode and a TE.sub.20 mode, where the end of the third rectangular waveguide port includes rounded edges that are parallel to a z-axis of the waveguide, a circular waveguide having a circular waveguide port for supporting a left hand and a right hand circular polarization TE.sub.11 mode and is coupled to a base arm broad wall, and a matching feature disposed on the base arm broad wall opposite of the circular waveguide for terminating the third rectangular waveguide port, where the first rectangular waveguide port, the second rectangular waveguide port and the circular waveguide port are capable of supporting 4-modes of operation.

  11. BATSE Observations of the Large-Scale Isotropy of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Briggs, Michael S.; Paciesas, William S.; Pendleton, Geoffrey N.; Meegan, Charles A.; Fishman, Gerald J.; Horack, John M.; Brock, Martin N.; Kouveliotou, Chryssa; Hartmann, Dieter H.; Hakkila, Jon

    1996-01-01

    We use dipole and quadrupole statistics to test the large-scale isotropy of the first 1005 gamma-ray bursts observed by the Burst and Transient Source Experiment (BATSE). In addition to the entire sample of 1005 gamma-ray bursts, many subsets are examined. We use a variety of dipole and quadrupole statistics to search for Galactic and other predicted anisotropies and for anisotropies in a coordinate-system independent manner. We find the gamma-ray burst locations to be consistent with isotropy, e.g., for the total sample the observed Galactic dipole moment (cos theta) differs from the value predicted for isotropy by 0.9 sigma and the observed Galactic quadrupole moment (sin(exp 2) b - 1/3) by 0.3 sigma. We estimate for various models the anisotropies that could have been detected. If one-half of the locations were within 86 deg of the Galactic center, or within 28 deg of the Galactic plane, the ensuing dipole or quadrupole moment would have typically been detected at the 99% confidence level. We compare the observations with the dipole and quadrupole moments of various Galactic models. Several Galactic gamma-ray bursts models have moments within 2 sigma of the observations; most of the Galactic models proposed to date are no longer in acceptable agreement with the data. Although a spherical dark matter halo distribution could be consistent with the data, the required core radius is larger than the core radius of the dark matter halo used to explain the Galaxy's rotation curve. Gamma-ray bursts are much more isotropic than any observed Galactic population, strongly favoring but not requiring an origin at cosmological distances.

  12. THEMIS Observations of the Magnetopause Electron Diffusion Region: Large Amplitude Waves and Heated Electrons

    NASA Technical Reports Server (NTRS)

    Tang, Xiangwei; Cattell, Cynthia; Dombeck, John; Dai, Lei; Wilson, Lynn B. III; Breneman, Aaron; Hupack, Adam

    2013-01-01

    We present the first observations of large amplitude waves in a well-defined electron diffusion region based on the criteria described by Scudder et al at the subsolar magnetopause using data from one Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite. These waves identified as whistler mode waves, electrostatic solitary waves, lower hybrid waves, and electrostatic electron cyclotron waves, are observed in the same 12 s waveform capture and in association with signatures of active magnetic reconnection. The large amplitude waves in the electron diffusion region are coincident with abrupt increases in electron parallel temperature suggesting strong wave heating. The whistler mode waves, which are at the electron scale and which enable us to probe electron dynamics in the diffusion region were analyzed in detail. The energetic electrons (approx. 30 keV) within the electron diffusion region have anisotropic distributions with T(sub e(right angle))/T(sub e(parallel)) > 1 that may provide the free energy for the whistler mode waves. The energetic anisotropic electrons may be produced during the reconnection process. The whistler mode waves propagate away from the center of the "X-line" along magnetic field lines, suggesting that the electron diffusion region is a possible source region of the whistler mode waves.

  13. Confronting the relaxation mechanism for a large cosmological constant with observations

    SciTech Connect

    Basilakos, Spyros; Bauer, Florian; Solà, Joan E-mail: fbauerphysik@eml.cc

    2012-01-01

    In order to deal with a large cosmological constant a relaxation mechanism based on modified gravity has been proposed recently. By virtue of this mechanism the effect of the vacuum energy density of a given quantum field/string theory (no matter how big is its initial value in the early universe) can be neutralized dynamically, i.e. without fine tuning, and hence a Big Bang-like evolution of the cosmos becomes possible. Remarkably, a large class (F{sup n}{sub m}) of models of this kind, namely capable of dynamically adjusting the vacuum energy irrespective of its value and size, has been identified. In this paper, we carefully put them to the experimental test. By performing a joint likelihood analysis we confront these models with the most recent observational data on type Ia supernovae (SNIa), the Cosmic Microwave Background (CMB), the Baryonic Acoustic Oscillations (BAO) and the high redshift data on the expansion rate, so as to determine which ones are the most favored by observations. We compare the optimal relaxation models F{sup n}{sub m} found by this method with the standard or concordance ΛCDM model, and find that some of these models may appear as almost indistinguishable from it. Interestingly enough, this shows that it is possible to construct viable solutions to the tough cosmological fine tuning problem with models that display the same basic phenomenological features as the concordance model.

  14. Very Large Rain Drops from 2D Video Disdrometers and Concomitant Polarimetric Radar Observations

    NASA Technical Reports Server (NTRS)

    Thurai, Merhala; Gatlin, Patrick; Bringi, V. N.; Carey, Lawrence

    2014-01-01

    Drop size distribution (DSD) measurements using ground-based disdrometers (point measurements) have often been used to derive equations to relate radar observations to the integral rainfall parameters (Atlas et al. 1999, Bringi et al., 2003, Kozu et al., 2006, Tokay and Short, 1996, Ajayi and Owolabi, 1987, Battan, 1973). Disdrometers such as JWD, MRR and several others have a major limitation in measuring drops with equi-volume diameters (D(sub eq)) larger than 5 mm because they often rely on the velocity-diameter relationship which plateaus beyond this diameter range (Atlas et al., 1973, Gunn & Kinzer, 1949). Other disdrometers such as Parsivel also lack accuracy beyond this diameter range. The 2D video disdrometer (2DVD: Schönhuber et al., 2008) on the other hand gives drop-shape contours and velocities for each individual drop/hydrometeor falling through its sensor area; this provides a unique opportunity to study the role of very-large drops on radar measurements in particular those with polarimetric radar capability where DSDs with a significant component of very large drops may require special consideration given that the differential reflectivity and other polarimetric radar parameters including attenuation-correction methods will be sensitive to the concentrations of these large drops. A recent study on the occurrence of large drops by Gatlin et al. (2014) has compiled a large and diverse set of measurements made with the 2D video disdrometers from many locations around the globe. Some of the largest drops found in this study were 9 mm D(sub eq) and larger, and in this paper, we report on three such events, with maximum D(sub eq's) of 9.0, 9.1 and 9.7 mm, which occurred in Colorado, Northern Alabama, and Oklahoma, respectively. Detailed examination of the 2DVD data - in terms of shapes and fall velocities - has confirmed that these are fully-melted hydrometeors, although for the last case in Oklahoma, a bigger and non-fully-melted hydrometeor was also

  15. What controls drizzle initiation? Insights from a comparison of large-eddy simulations with observations

    NASA Astrophysics Data System (ADS)

    Witte, M.; Chuang, P. Y.; Wang, L. P.; Ayala, O.

    2014-12-01

    Drizzle occurs frequently in shallow, warm boundary layer clouds. For example, in stratocumulus it occurs approximately 1/3 of the time in full cloud cover conditions (Wood 2012). Drizzle affects moisture and energy budgets, and cloud albedo, morphology and lifetime. At the cloud scale, processes that control drizzle formation include turbulence production via radiative cooling and/or shear, entrainment, and surface moisture fluxes. At the micro-scale, collision-coalescence is the primary process relevant to warm drizzle formation. Differential gravitational sedimentation and turbulent air motions cause cloud droplets to collide, creating drops much larger than can be formed by condensation alone. Other factors, such as preferential concentration and entrainment mixing may also be relevant. The process is typically subdivided into three regimes: autoconversion (small drops self-collide), accretion (large drops collect small drops), and hydrometeor self-collection (large drops self-collide). Of these regimes, autoconversion is the rate-limiting step in existing analytical representations. This study (i) evaluates whether our best theoretical understanding of collision-coalescence in the autoconversion regime can replicate observations, with a broader goal of (ii) exploring which cloud-scale factors are most important for drizzle initiation. A state-of-the-art turbulent collisional growth model is applied to a bin microphysics scheme within a large-eddy simulation such that the full range of cloud drop growth mechanisms are represented (i.e. CCN activation, condensation, collision-coalescence, mixing, etc.) at realistic atmospheric conditions. We compare cloud drop spectra produced by the LES with observations to assess the quality and limits of our theoretical knowledge. The comparison will be performed over a range of observational cases that span a range of drizzle rates. These cases differ in their radiative cooling rates, shear, cloud-top temperature and

  16. CIRCULAR RIBBON FLARES AND HOMOLOGOUS JETS

    SciTech Connect

    Wang Haimin; Liu Chang

    2012-12-01

    Solar flare emissions in the chromosphere often appear as elongated ribbons on both sides of the magnetic polarity inversion line (PIL), which has been regarded as evidence of a typical configuration of magnetic reconnection. However, flares having a circular ribbon have rarely been reported, although it is expected in the fan-spine magnetic topology involving reconnection at a three-dimensional (3D) coronal null point. We present five circular ribbon flares with associated surges, using high-resolution and high-cadence H{alpha} blue wing observations obtained from the recently digitized films of Big Bear Solar Observatory. In all the events, a central parasitic magnetic field is encompassed by the opposite polarity, forming a circular PIL traced by filament material. Consequently, a flare kernel at the center is surrounded by a circular flare ribbon. The four homologous jet-related flares on 1991 March 17 and 18 are of particular interest, as (1) the circular ribbons brighten sequentially, with cospatial surges, rather than simultaneously, (2) the central flare kernels show an intriguing 'round-trip' motion and become elongated, and (3) remote brightenings occur at a region with the same magnetic polarity as the central parasitic field and are co-temporal with a separate phase of flare emissions. In another flare on 1991 February 25, the circular flare emission and surge activity occur successively, and the event could be associated with magnetic flux cancellation across the circular PIL. We discuss the implications of these observations combining circular flare ribbons, homologous jets, and remote brightenings for understanding the dynamics of 3D magnetic restructuring.

  17. Circular polarisation in star-forming regions: possible implications for homochirality.

    PubMed

    Hough, J H; Bailey, J A; Chrysostomou, A; Gledhill, T M; Lucas, P W; Tamura, M; Clark, S; Yates, J; Menard, F

    2001-01-01

    Our discovery of high degrees of circular polarisation in some star-forming regions provides an attractive mechanism for the origin of homochirality. The largest degrees of circular polarisation, so far observed at near-infrared wavelengths, are thought to arise from the scattering of stellar radiation from aligned dust grains and are calculated to extend down to UV wavelengths. The extent of the region where circularly polarised light (CPL) of a single handedness originates is very large, and it is likely that the whole of a planetary system would see a single handedness of CPL also. We present the observational data, models of the scattering that leads to the production of CPL, and a model for the origin of homochirality. We also discuss briefly future laboratory and space-based experiments.

  18. Sky surface brightness at Mount Graham II. First JHKs science observations with the Large Binocular Telescope

    NASA Astrophysics Data System (ADS)

    Pedani, M.

    2014-04-01

    We studied the near-infrared sky-brightness at J, H and Ks-bands as derived from the data taken during the first year and a half of routine science operations of the Large Binocular Telescope (LBT). This is the first comprehensive study of the near-infrared night sky-brightness ever conducted at the Mount Graham International Observatory (MGIO), based on a large dataset comprising 4699 near-infrared images taken in 52 nights. We analyzed the dependency of the near-infrared night sky-brightness with the airmass, the season and the moon phase and distance. The average night sky-brightnesses (dispersion) in the J, H and Ks bands scaled to the zenith is 15.82 mag/arcsec2 (0.21), 14.29 mag/arcsec2 (0.26) and 13.42 mag/arcsec2 (0.32) respectively. Those values were derived for the first time at this observatory. At the J-band we found a tendency of the sky background to get darker by ˜0.35 mag at the end of the night with respect to the evening twilight. Also in the J-band we found that the sky background can be up to ˜0.11 mag brighter when observing at 10° distance from the full moon. A correlation was also found between the night sky-brightness in the Ks-band and the air temperature with a gradient of -0.06 mag per 1°C of temperature increase. If we compare the average sky brightness of the major observing sites we find that, at J-band, Mt. Graham is quite similar to the major sites but it quickly becomes the second darkest place at the H-band and definitely the darkest observing site at the Ks-band together with Mauna Kea.

  19. Determining large-scale heliospheric structure using ultraviolet resonance line observations

    NASA Technical Reports Server (NTRS)

    Hall, Doyle T.

    1995-01-01

    Currently the Pioneer 10 and Voyager 1 and 2 spacecraft are beyond the orbit of Pluto, traveling outward from the Sun. Each is capable of detecting ultraviolet radiation resonantly scattered from hydrogen and helium atoms in the heliosphere and local interstellar medium. These observations are particularly well suited for the investigation of the large-scale heliospheric H and He distributions because the Voyager spacecraft are heading upstream, into the direction of local interstellar flow, whereas Pioneer 10 is heading downstream. Observations of the brightest resonance line, H Lyman-alpha, reveals that beyond about 20 AU from the Sun, upstream intensities decrease less quickly as a function of solar distance than downstream intensities. This implies that the heliospheric H distributions in the upstream and downstream directions are significantly different. Heliospheric H atoms originate in the local interstellar flow, and must penetrate through the heliospheric interface, where they are subject to charge exchange collisions with solar wind and interstellar protons. Models indicate that this process is probably responsible for the upstream/downstream difference in H Lyman-alpha. In addition, a recent spectroscopic determination of the H atom velocity distribution in the inner heliosphere implies a significant deceleration in the bulk flow speed of the heliospheric hydrogen gas relative to the helium flow, an effect that is also likely due to H-p charge exchange occurring in the upstream heliospheric interface region. In this presentation, recent heliospheric resonance line observations and their interpretations will be reviewed, focusing on their sensitivity to large-scale heliospheric structure.

  20. Sunyaev-Zel'dovich Observations Using Large-Format Millimeter Arrays

    NASA Astrophysics Data System (ADS)

    Czakon, Nicole G.

    Galaxy clusters are the largest gravitationally bound objects in the observable universe, and they are formed from the largest perturbations of the primordial matter power spectrum. During initial cluster collapse, matter is accelerated to supersonic velocities, and the baryonic component is heated as it passes through accretion shocks. This process stabilizes when the pressure of the bound matter prevents further gravitational collapse. Galaxy clusters are useful cosmological probes, because their formation progressively freezes out at the epoch when dark energy begins to dominate the expansion and energy density of the universe. A diverse set of observables, from radio through X-ray wavelengths, are sourced from galaxy clusters, and this is useful for self-calibration. The distributions of these observables trace a cluster's dark matter halo, which represents more than 80% of the cluster's gravitational potential. One such observable is the Sunyaev-Zel'dovich effect (SZE), which results when the ionized intercluster medium blueshifts the cosmic microwave background via Compton scattering. Great technical advances in the last several decades have made regular observation of the SZE possible. Resolved SZE science, such as is explored in this analysis, has benefitted from the construction of large-format camera arrays consisting of highly sensitive millimeter-wave detectors, such as Bolocam. Bolocam is a submillimeter camera, sensitive to 140 GHz and 268 GHz radiation, located at one of the best observing sites in the world: the Caltech Submillimeter Observatory on Mauna Kea in Hawaii. Bolocam fielded 144 of the original spider web NTD bolometers used in an entire generation of ground-based, balloon-borne, and satellite-borne millimeter wave instrumention. Over approximately six years, our group at Caltech has developed a mature galaxy cluster observational program with Bolocam. This thesis describes the construction of the instrument's full cluster catalog: BOXSZ

  1. Circular Fibonacci gratings.

    PubMed

    Gao, Nan; Zhang, Yuchao; Xie, Changqing

    2011-11-01

    We introduce circular Fibonacci gratings (CFGs) that combine the concept of circular gratings and Fibonacci structures. Theoretical analysis shows that the diffraction pattern of CFGs is composed of fractal distributions of impulse rings. Numerical simulations are performed with two-dimensional fast Fourier transform to reveal the fractal behavior of the diffraction rings. Experimental results are also presented and agree well with the numerical results. The fractal nature of the diffraction field should be of great theoretical interest, and shows potential to be further developed into practical applications, such as in laser measurement with wideband illumination.

  2. From AGBs to PNe: understanding the observations of evolved stars in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Dell'Agli, Flavia

    2015-08-01

    Asymptotic Giant Branch (AGB) stars represent one of the main stellar sources for dust production in the Universe. We provide a description of the formation and growth of dust particles in the circumstellar envelope of AGBs, based on detailed calculations of the AGB evolutionary phase. We use stellar population synthesis to interpret the Spitzer observations of dusty AGBs in the Large Magellanic Cloud (LMC). Our results show that carbon-rich and oxygen-rich stars evolve into different and separated regions of the observational diagrams obtained with the Spitzer bands. This allows a straight comparison with the spectroscopically confirmed samples of AGBs in the LMC present in the literature. The overall impact of AGBs on the dust production rate in the LMC is also discussed.The interpretation of the AGB population of the LMC is used to describe the observed chemical abundances of the Planetary Nebulae in the same galaxy. This analysis outlines a clear distinction between stars which experience Hot Bottom Burning and those the Third Dredge Up.

  3. Variable Stars in the Large Magellanic Cloud from Archival HST Observations

    NASA Astrophysics Data System (ADS)

    Alejandro Fuentes, Gabriel; Sarajedini, Ata

    2017-01-01

    In this study, we present deep observations of a field in the Large Magellanic Cloud (LMC) taken by the Advanced Camera for Surveys onboard the Hubble Space Telescope (HST) in coordinated parallel mode. While HST was observing SN1987a with the primary instrument, it was able to collect 42 images of a nearby field in the LMC over a timespan of 3.92 hours in the F606W (~V) and F814W (~I) filters. These deep observations allow us to search for variable stars from the level of the horizontal branch (HB) down to several magnitudes below the main sequence turnoff. We make use of existing light-curve-template fitting software in order to derive periods and amplitudes for our candidate variable stars. This approach complements the existing LMC variable star surveys, which are primarily designed to identify these stars at or above the HB. This results in ~10 magnitudes of coverage in the search for variables in the LMC.

  4. Investigation of natural gas plume dispersion using mobile observations and large eddy simulations

    NASA Astrophysics Data System (ADS)

    Caulton, Dana R.; Li, Qi; Golston, Levi; Pan, Da; Bou-Zeid, Elie; Fitts, Jeff; Lane, Haley; Lu, Jessica; Zondlo, Mark A.

    2016-04-01

    Recent work suggests the distribution of methane emissions from fracking operations is skewed with a small percentage of emitters contributing a large proportion of the total emissions. These sites are known as 'super-emitters.' The Marcellus shale, the most productive natural gas shale field in the United States, has received less intense focus for well-level emissions and is here used as a test site for targeted analysis between current standard trace-gas advection practices and possible improvements via advanced modeling techniques. The Marcellus shale is topographically complex, making traditional techniques difficult to implement and evaluate. For many ground based mobile studies, the inverse Gaussian plume method (IGM) is used to produce emission rates. This method is best applied to well-mixed plumes from strong point sources and may not currently be well-suited for use with disperse weak sources, short-time frame measurements or data collected in complex terrain. To assess the quality of IGM results and to improve source-strength estimations, a robust study that combines observational data with a hierarchy of models of increasing complexity will be presented. The field test sites were sampled with multiple passes using a mobile lab as well as a stationary tower. This mobile lab includes a Garmin GPS unit, Vaisala weather station (WTX520), LICOR 7700 CH4 open path sensor and LICOR 7500 CO2/H2O open path sensor. The sampling tower was constructed consisting of a Metek uSonic-3 Class A sonic anemometer, and an additional LICOR 7700 and 7500. Data were recorded for at least one hour at these sites. The modeling will focus on large eddy simulations (LES) of the wind and CH4 concentration fields for these test sites. The LES model used 2 m horizontal and 1 m vertical resolution and was integrated in time for 45 min for various test sites under stable, neutral and unstable conditions. It is here considered as the reference to which various IGM approaches can be

  5. A secure and reliable monitor and control system for remote observing with the Large Millimeter Telescope

    NASA Astrophysics Data System (ADS)

    Wallace, Gary; Souccar, Kamal; Malin, Daniella

    2004-09-01

    Remote access to telescope monitor and control capabilities necessitates strict security mechanisms to protect the telescope and instruments from malicious or unauthorized use, and to prevent data from being stolen, altered, or corrupted. The Large Millimeter Telescope (LMT) monitor and control system (LMTMC) utilizes the Common Object Request Broker Architecture (CORBA) middleware technology to connect remote software components. The LMTMC provides reliable and secure remote observing by automatically generating SSLIOP enabled CORBA objects. TAO, the ACE open source Object Request Broker (ORB), now supports secure communications by implementing the Secure Socket Layer Inter-ORB Protocol (SSLIOP) as a pluggable protocol. This capability supplies the LMTMC with client and server authentication, data integrity, and encryption. Our system takes advantage of the hooks provided by TAO SSLIOP to implement X.509 certificate based authorization. This access control scheme includes multiple authorization levels to enable granular access control.

  6. Fermi Large Area Telescope observations of high-energy gamma-ray emission from Solar flares

    NASA Astrophysics Data System (ADS)

    Pesce Rollins, Melissa

    2017-01-01

    The Fermi Large Area Telescope (LAT) observations of the active Sun provide the largest sample of detected solar flares with emission greater than 30 MeV to date. These include detections of impulsive and sustained emission, extending up to 20 hours in the case of the 2012 March 7 X-class flares. These high-energy flares are coincident with GOES X-ray flares of X, M and C classes as well as very fast Coronal Mass Ejections (CME). We will present results from the First Fermi-LAT solar flare catalog covering the majority of Solar Cycle 24 including correlation studies with the associated Solar Energetic Particles (SEP) and CMEs.

  7. Large Angular Jump Mechanism Observed for Hydrogen Bond Exchange in Aqueous Perchlorate Solution

    SciTech Connect

    Ji, Minbiao; Odelius3, Michael; Gaffney1, K.J.; /aff SLAC, PULSE

    2010-06-11

    The mechanism for hydrogen bond (H-bond) switching in solution has remained subject to debate despite extensive experimental and theoretical studies. We have applied polarization-selective multidimensional vibrational spectroscopy to investigate the H-bond exchange mechanism in aqueous NaClO{sub 4} solution. The results show that a water molecule shifts its donated H-bonds between water and perchlorate acceptors by means of large, prompt angular rotation. Using a jump-exchange kinetic model, we extract an average jump angle of 49 {+-} 4{sup o}, in qualitative agreement with the jump angle observed in molecular dynamics simulations of the same aqueous NaClO{sub 4} solution.

  8. Corotating structures in the solar wind from 111-MHz observations of interplanetary scintillations at large elongations

    NASA Astrophysics Data System (ADS)

    Glyantsev, A. V.; Tyul'bashev, S. A.; Chashei, I. V.; Shishov, V. I.; Potapova, L. B.

    2017-03-01

    Results of continuous 111 MHz observations of interplanetary scintillations of the strong radio source 3C 48 at elongations larger than 80° out on the Large Phased Array (LPA) of the Lebedev Physical Institute are reported. The data were taken during a four-year interval, from 2012 to 2015, near the maximum of the 24th solar-activity cycle. The averaged elongation dependence of the scintillation index and similar dependences for individual years during the approach and recession phases suggest the presence of a periodic modulation with a 26-day period, which is masked by day-to-day variations. This periodic modulation can be explained by the existence of a long-lived region of enhanced plasma density adjacent to the solar equator during the solar-activity maximum. It is shown that the scintillation timescale increases in the transition to elongations exceeding 90°.

  9. Galaxy evolution and large-scale structure in the far-infrared. I - IRAS pointed observations

    NASA Astrophysics Data System (ADS)

    Lonsdale, Carol J.; Hacking, Perry B.

    1989-04-01

    Redshifts for 66 galaxies were obtained from a sample of 93 60-micron sources detected serendipitously in 22 IRAS deep pointed observations, covering a total area of 18.4 sq deg. The flux density limit of this survey is 150 mJy, 4 times fainter than the IRAS Point Source Catalog (PSC). The luminosity function is similar in shape with those previously published for samples selected from the PSC, with a median redshift of 0.048 for the fainter sample, but shifted to higher space densities. There is evidence that some of the excess number counts in the deeper sample can be explained in terms of a large-scale density enhancement beyond the Pavo-Indus supercluster. In addition, the faintest counts in the new sample confirm the result of Hacking et al. (1989) that faint IRAS 60-micron source counts lie significantly in excess of an extrapolation of the PSC counts assuming no luminosity or density evolution.

  10. Galaxy evolution and large-scale structure in the far-infrared. I - IRAS pointed observations

    NASA Technical Reports Server (NTRS)

    Lonsdale, Carol J.; Hacking, Perry B.

    1989-01-01

    Redshifts for 66 galaxies were obtained from a sample of 93 60-micron sources detected serendipitously in 22 IRAS deep pointed observations, covering a total area of 18.4 sq deg. The flux density limit of this survey is 150 mJy, 4 times fainter than the IRAS Point Source Catalog (PSC). The luminosity function is similar in shape with those previously published for samples selected from the PSC, with a median redshift of 0.048 for the fainter sample, but shifted to higher space densities. There is evidence that some of the excess number counts in the deeper sample can be explained in terms of a large-scale density enhancement beyond the Pavo-Indus supercluster. In addition, the faintest counts in the new sample confirm the result of Hacking et al. (1989) that faint IRAS 60-micron source counts lie significantly in excess of an extrapolation of the PSC counts assuming no luminosity or density evolution.

  11. The 2-D Curvature of Large Angle Interplanetary MHD Discontinuity Surfaces: IMP-8 and WIND Observations

    NASA Astrophysics Data System (ADS)

    Lepping, R. P.; Wu, C.; McClernan, K.

    2002-12-01

    This study examines the degree of 2-D curvature of solar wind directional discontinuity (DD) surfaces at 1 AU using magnetic field, density, and velocity data from the WIND and IMP-8 spacecraft for a large number (N = 134) of carefully selected events having large ``discontinuity angles" of 90° or greater. The discontinuity angle (ω ) is measured in the DDs current sheet, the normal to which is estimated by field variance analysis. The fundamental analysis depends on estimates of these DD surface normals at the two spacecraft, and the DDs center-times and positions. On average, the transit time from one DD sighting to the other was 36 minutes, and the associated distance along the normal direction was 137 RE. The transition-interval lengths across the DDs are translated into thicknesses and examined for the amount of change between the two spacecraft observing points; average thickness is relatively large, 14 RE. All relevant quantities are examined statistically to establish their distributions, average, and degree of change. A weighted average of the radius of curvature is estimated to be 380 RE, but its most probably value is 290 RE. The average ω is 140° with a relatively large spread (σ =28°). The average direction of propagation is: longitude = 194° and latitude = 7° (but < ∣ lat∣ > = 27°). Various parameters are studied with respect to DD type, defined in terms the ratio of speed of propagation to net speed (``ratio") of the DD surface, (the RD ratio is high and the TD ratio is very low or zero). The results by this definition of type are favorably compared to those from the more conventional method, which depends on the absolute strength of the normal component of the magnetic field. There is little difference in any average parameter value according to type. However, the average ω appears to depend slightly on type with the < ω > for the RDs being smaller. A DDs type was shown to change in either direction between the two observation

  12. Two-dimensional curvature of large angle interplanetary MHD discontinuity surfaces: IMP-8 and WIND observations

    NASA Astrophysics Data System (ADS)

    Lepping, R. P.; Wu, C.-C.; McClernan, K.

    2003-07-01

    This study examines the degree of two-dimensional curvature of solar wind directional discontinuity (DD) surfaces at 1 AU using magnetic field, density, and velocity data from the WIND and IMP-8 spacecraft for a large number (N = 134) of carefully selected events having large "discontinuity angles" of 90° or greater. The discontinuity angle (ω) is measured in the DD's current sheet, the normal (n) to which is estimated by field variance analysis. The fundamental analysis depends on estimates of these DD surface normals at the two spacecraft and the DD's center-times and positions. On average, the transit time from one DD sighting to the other was 36 minutes, and the associated distance along the normal direction was 137 RE. The transition-interval lengths across the DDs are translated into thicknesses and examined for the amount of change between the two spacecraft observing points. The average thickness is relatively large, 14 RE.; the most probable thickness is ≈6 RE. All relevant quantities are examined statistically to establish their distributions, average, and degree of change. A weighted average of the radius of curvature is estimated to be 380 RE, but its most probable value is 290 RE. The average ω is 140° with a relatively large spread (σ = 28°). The average direction of propagation is: longitude (ϕn) = 194° and latitude (θn) = 7° (but <∣θn∣> = 27°), where ϕn = 0° is sunward and θn = 0° is the ecliptic plane. Various parameters are studied with respect to DD type, i.e., rotational or tangential discontinuity (RD or TD), defined in terms of the "ratio" (in percent) of speed of propagation to net speed of the DD surface, where the net speed is the sum of the convection velocity (along n) plus the propagation speed. The RD %-ratio is moderately small, but the TD ratio is very small or zero. The results by this definition of type are favorably compared to those from the more conventional method, which depends on the absolute strength of

  13. Relationships Within the Precurors Before Large Earthquakes: Theory, Observations and Data Chosen

    NASA Astrophysics Data System (ADS)

    Mingyu, J.

    2015-12-01

    The Non-Critical Precursory Accelerating Seismicity Theory has been partly tested (with the method of RTL) about the same spatiotemporal window of both accelerating seismicity and quiescence, which may relate the two of the principal patterns that can precede large earthquakes. The Accelerating Moment/Strain Releasing model could be seen as the loading process between the reduced seismicity after the last huge earthquakes around the epicenter and the next rupture. So the AMR model depends on the occurrence of the quiescence. Here, we develop an approach based on the concept of stress accumulation to unify and categorize all claimed seismic precursors in a same physical framework, including the quiescence, the AMR/ASR model and the short-term activation. It shows that different precursory paths are possible before large earthquakes and can be described by a logic tree with combined criteria at a given stress state and of precursory silent slip on the fault and within the faults system. Theoretical results are then compared to the time series observed prior to the earthquake catalog from 1980 to 2012, Italy. In the initial result, the case of the 2009 Mw = 6.3 L'Aquila earthquake, Italy, the observed precursory path is coupling of quiescence and accelerating seismic release, followed by activation. What's more, the comparison between ETAS and Stress Accumulation Model shows that precursors are statistic significant when microseismicity is considered, which holds important information on the stress loading state of the crust surrounding active faults. Based on the corrected Akaike Information Criterion (AICc), we found that quiescence and ASR signals are significant when events below a magnitude of 2.2 are included and that short-term activation is significant when events below 3.3 are included. These results provide guidelines for future research on earthquake regional risk assessment and some kind of predictability.

  14. Large-scale and Convective-scale Updraft Profiles from Satellite Observations

    NASA Astrophysics Data System (ADS)

    Masunaga, H.; Luo, Z. J.

    2015-12-01

    Among the crucial problems involved in the tropical energy budget are the thermodynamic effects of an ensemble of convective clouds on their environment and the large-scale influence imposed back on the convective-scale dynamics. Efforts to seek observational evidence for this problem, however, are challenged by limitations in the capability of measuring vertical motion across different horizontal scales. We have recently been exploring new analysis strategies in hopes to make this seemingly impossible possible, exploiting a suite of satellite instruments including the CloudSat and TRMM radars and Aqua AIRS. Since a complete vertical structure of in-cloud vertical velocity, wc, is unable to be reconstructed from satellite measurements alone, a single-column plume model is run with the environmental soundings from AIRS to obtain a set of synthetic wc profiles under a range of entrainment rates. The solutions are then narrowed down in a Bayesian manner so as to match the cloud-top vertical velocity and buoyancy estimates from A-Train infrared and radar measurements. The vertical profile of large-scale mean vertical motion, ω, is also evaluated from satellite observations in its own approach: ω as a function of pressure is determined so that it satisfies the horizontal divergence terms in the tropospheric water and thermal budget equations in which the remaining terms are constrained by satellite measurements. In this talk, the methodology is briefly outlined and the results are presented and discussed in light of outstanding issues in tropical dynamics. The wc and ω estimates above, although subject to intrinsic uncertainties yet to be verified, do not involve any closure assumption as required for cumulus parameterizations and would offer a useful test bed for climate models and reanalysis data as well as a unique opportunity to study the mechanism of tropical convection.

  15. Observing the Moon at Microwave Frequencies Using a Large-Diameter Deep Space Network Antenna

    NASA Astrophysics Data System (ADS)

    Morabito, David D.; Imbriale, William; Keihm, Stephen

    2008-03-01

    The Moon radiates energy at infrared and microwave wavelengths, in addition to reflecting sunlight at optical wavelengths. As a result, an antenna pointed at or near the Moon will result in an increase in system operating noise temperature, which needs to be accounted for in RF telecommunications, radio science or radiometric link calculations. The NASA Deep Space Network (DSN) may use its large-diameter antennas in future lunar robotic or human missions, and thus it is important to understand the nature of this temperature incre ase as a function of observing frequency, lunar phase, and angular position of the antenna beam on the lunar disk. This paper reports on a comprehensive lunar noise temperature measurement campaign and associated theoretical treatment for a 34-m diameter Deep Space Network antenna observing an extended source such as the Moon. A set of measurements over a wide range of lunar phase angles was acquired at DSS-13, a 34-m diameter beam waveguide antenna (BWG) located at Goldstone, California at 2.3 GHz (S-band), 8.4 GHz (X-band) and 32 GHz (Ka-band). For validation purposes, independent predictions of noise temperature increase were derived using a physical optics characterization of the 34-m diameter antenna gain patterns and Apollo model-based brightness temperature maps of the Moon as input. The model-based predictions of noise temperature increase were compared with the measurements at all three frequencies. In addition, a methodology is presented that relates noise temperature increase due to the Moon to disk-centered or disk-averaged brightness temperature of the Moon at the microwave frequencies of interest. Comparisons were made between the measurements and models in the domain of lunar disk-centered and disk-averaged brightness temperatures. It is anticipated that the measurements and associated theoretical development will be useful in developing telecommunications strategies for future high-rate Ka-band communications where large

  16. Plasma signatures in large Martian magnetic flux ropes: MARSIS/ASPERA-3 observations

    NASA Astrophysics Data System (ADS)

    Diéval, Catherine; Morgan, David; Duru, Firdevs; Gurnett, Donald

    2014-05-01

    Cylindrical structures of highly twisted magnetic field (flux ropes) have been observed at Mars, using measurements by the MAG-ER magnetometer-electron reflectometer onboard Mars Global Surveyor (MGS) and by the MARSIS radar sounder onboard Mars Express (MEX). Signatures of flux ropes are spikes of magnetic field strength and magnetic field rotations. Both small scale flux ropes (diameters of a few tens of km) and large scale flux ropes (diameters of around 100 km) have been found at Mars. We look at times of presumed flux ropes on the dayside of Mars, detected in the local magnetic field strength given by MARSIS. The signatures in MARSIS are magnetic field strength increases (peak strength reaches several tens to hundred nT) for several minutes (size of hundreds of km along the spacecraft track), found outside but near crustal magnetic field regions. Although we cannot determine the presence of a magnetic field rotation because of the lack of a magnetometer onboard MEX, we assume that these magnetic field increases are large flux ropes. There are indeed large flux ropes with similar characteristics which were established by the magnetometer data from MGS, and thought to form by stretching and reconnection of crustal magnetic field by the solar wind. On the other hand, MEX possesses in situ ion measurements, unlike MGS. We will use the ion and electron data from the ASPERA-3 particle instrument onboard MEX in order to characterize the plasma (ionospheric only or mixing with shocked plasma?) inside the flux ropes, which will give hints on their origin.

  17. Changes in the Molar Ellipticities of HEWL Observed by Circular Dichroism and Quantitated by Time Resolved Fluorescence Anisotropy Under Crystallizing Conditions

    NASA Technical Reports Server (NTRS)

    Sumida, John

    2002-01-01

    Fluid models for simple colloids predict that as the protein concentration is increased, crystallization should occur at some sufficiently high concentration regardless of the strength of attraction. However, empirical measurements do not fully support this assertion. Measurements of the second virial coefficient (B22) indicate that protein crystallization occurs only over a discrete range of solution parameters. Furthermore, observations of a strong correlation between protein solubility and B22, has led to an ongoing debate regarding the relationship between the two. Experimental work in our lab, using Hen Egg White Lysozyme (HEWL), previously revealed that the rotational anisotropy of the protein under crystallizing conditions changes systematically with pH, ionic strength and temperature. These observations are now supported by recent work revealing that small changes in the molar ellipticity also occur systematically with changes in ionic strength and temperature. This work demonstrates that under crystallization conditions, the protein native state is characterized by a conformational heterogeneity that may prove fundamental to the relationship between protein crystallization and protein solubility.

  18. Wiimote Experiments: Circular Motion

    ERIC Educational Resources Information Center

    Kouh, Minjoon; Holz, Danielle; Kawam, Alae; Lamont, Mary

    2013-01-01

    The advent of new sensor technologies can provide new ways of exploring fundamental physics. In this paper, we show how a Wiimote, which is a handheld remote controller for the Nintendo Wii video game system with an accelerometer, can be used to study the dynamics of circular motion with a very simple setup such as an old record player or a…

  19. Wiimote Experiments: Circular Motion

    NASA Astrophysics Data System (ADS)

    Kouh, Minjoon; Holz, Danielle; Kawam, Alae; Lamont, Mary

    2013-03-01

    The advent of new sensor technologies can provide new ways of exploring fundamental physics. In this paper, we show how a Wiimote, which is a handheld remote controller for the Nintendo Wii video game system with an accelerometer, can be used to study the dynamics of circular motion with a very simple setup such as an old record player or a bicycle wheel.

  20. Copyright Basics. Circular 1.

    ERIC Educational Resources Information Center

    Library of Congress, Washington, DC. Copyright Office.

    This circular answers some of the questions that are frequently asked about copyright, a form of protection provided by the laws of the United States to authors of "original works of authorship" including library, dramatic musical, artistic, and certain other intellectual works. The Copyright Act of 1976 (title 17 of the United States…

  1. Transposable elements and circular DNAs

    PubMed Central

    2016-01-01

    ABSTRACT Circular DNAs are extra-chromosomal fragments that become circularized by genomic recombination events. We have recently shown that yeast LTR elements generate circular DNAs through recombination events between their flanking long terminal repeats (LTRs). Similarly, circular DNAs can be generated by recombination between LTRs residing at different genomic loci, in which case the circular DNA will contain the intervening sequence. In yeast, this can result in gene copy number variations when circles contain genes and origins of replication. Here, I speculate on the potential and implications of circular DNAs generated through recombination between human transposable elements. PMID:28090380

  2. Catalogue of Large Magellanic Cloud star clusters observed in the Washington photometric system

    NASA Astrophysics Data System (ADS)

    Palma, T.; Gramajo, L. V.; Clariá, J. J.; Lares, M.; Geisler, D.; Ahumada, A. V.

    2016-02-01

    Aims: The main goal of this study is to compile a catalogue of the fundamental parameters of a complete sample of 277 star clusters (SCs) of the Large Magellanic Cloud (LMC) observed in the Washington photometric system. A set of 82 clusters was recently studied by our team. Methods: All the clusters' parameters such as radii, deprojected distances, reddenings, ages, and metallicities were obtained by applying essentially the same procedures, which are briefly described here. We used empirical cumulative distribution functions to examine age, metallicity and deprojected distance distributions for different cluster subsamples of the catalogue. Results: Our new sample of 82 additional clusters represents about a 40% increase in the total number of LMC SCs observed to date in the Washington photometric system. In particular, we report here the fundamental parameters obtained for the first time for 42 of these clusters. We found that single LMC SCs are typically older than multiple SCs. Both single and multiple SCs exhibit asymmetrical distributions in log (age). We compared cluster ages derived through isochrone fittings obtained using different models of the Padova group. Although ages obtained using recent isochrones are consistent in general terms, we found that there is some disagreement in the obtained values and their uncertainties.

  3. Method for optimizing channelized quadratic observers for binary classification of large-dimensional image datasets

    PubMed Central

    Kupinski, M. K.; Clarkson, E.

    2015-01-01

    We present a new method for computing optimized channels for channelized quadratic observers (CQO) that is feasible for high-dimensional image data. The method for calculating channels is applicable in general and optimal for Gaussian distributed image data. Gradient-based algorithms for determining the channels are presented for five different information-based figures of merit (FOMs). Analytic solutions for the optimum channels for each of the five FOMs are derived for the case of equal mean data for both classes. The optimum channels for three of the FOMs under the equal mean condition are shown to be the same. This result is critical since some of the FOMs are much easier to compute. Implementing the CQO requires a set of channels and the first- and second-order statistics of channelized image data from both classes. The dimensionality reduction from M measurements to L channels is a critical advantage of CQO since estimating image statistics from channelized data requires smaller sample sizes and inverting a smaller covariance matrix is easier. In a simulation study we compare the performance of ideal and Hotelling observers to CQO. The optimal CQO channels are calculated using both eigenanalysis and a new gradient-based algorithm for maximizing Jeffrey's divergence (J). Optimal channel selection without eigenanalysis makes the J-CQO on large-dimensional image data feasible. PMID:26366764

  4. SDO/AIA OBSERVATIONS OF LARGE-AMPLITUDE LONGITUDINAL OSCILLATIONS IN A SOLAR FILAMENT

    SciTech Connect

    Li Ting; Zhang Jun E-mail: zjun@nao.cas.cn

    2012-11-20

    We present the first Solar Dynamics Observatory/Atmospheric Imaging Assembly observations of the large-amplitude longitudinal (LAL) oscillations in the south and north parts (SP and NP) of a solar filament on 2012 April 7. Both oscillations are triggered by flare activities close to the filament. The period varies with filamentary threads, ranging from 44 to 67 minutes. The oscillations of different threads are out of phase, and their velocity amplitudes vary from 30 to 60 km s{sup -1}, with a maximum displacement of about 25 Mm. The oscillations of the SP repeat for about four cycles without any significant damping and then a nearby C2.4 flare causes the transition from the LAL oscillations of the filament to its later eruption. The filament eruption is also associated with a coronal mass ejection and a B6.8 flare. However, the oscillations of the NP damp with time and die out at last. Our observations show that the activated part of the SP repeatedly shows a helical motion. This indicates that the magnetic structure of the filament is possibly modified during this process. We suggest that the restoring force is the coupling of the magnetic tension and gravity.

  5. Large-Field CO(J = 1→0) Observations of the Starburst Galaxy M 82

    NASA Astrophysics Data System (ADS)

    Salak, Dragan; Nakai, Naomasa; Miyamoto, Yusuke; Yamauchi, Aya; Tsuru, Takeshi G.

    2013-06-01

    We present large-field (15.7 × 16.9 arcmin2) CO(J = 1→0) observations of the starburst galaxy M 82, at an angular resolution of 22" with the NRO 45-m telescope. The CO emission was detected in the galactic disk, outflow (driven by the galactic wind) up to ˜2 kpc above the galactic plane in the halo, and in tidal streams. The kinematics of the outflow (including CO line splitting) suggests that it has the shape of a cylinder that is diverging outwards. The mass and kinetic energy of the molecular gas outflow are estimated to be (0.26-1.0) × 109 M⊙ and (1-4) × 1056 erg. A clump of CO gas was discovered 3.5 kpc above the galactic plane; it coincides with a dark lane previously found in X-ray observations, and a peak in H I emission. A comparison with H I, hot molecular hydrogen and dust suggests that the molecular gas shows signatures of warm and cool components in the outflow and tidal streams, respectively.

  6. Observations of large-scale fluid transport by laser-guided plankton aggregationsa)

    NASA Astrophysics Data System (ADS)

    Wilhelmus, Monica M.; Dabiri, John O.

    2014-10-01

    Diel vertical migration of plankton has been proposed to affect global ocean circulation to a degree comparable to winds and tides. This biomixing process has never been directly observed, however, due to the inability to predict its occurrence in situ or to reproduce it in a laboratory setting. Furthermore, it has been argued that the energy imparted to the ocean by plankton migrations occurs at the scale of individual organisms, which is too small to impact ocean mixing. We describe the development of a multi-laser guidance system that leverages the phototactic abilities of plankton to achieve controllable vertical migrations concurrently with laser velocimetry of the surrounding flow. Measurements in unstratified fluid show that the hydrodynamic interactions between neighboring swimmers establish an alternate energy transfer route from the small scales of individually migrating plankton to significantly larger scales. Observations of laser-induced vertical migrations of Artemia salina reveal the appearance of a downward jet, which triggers a Kelvin-Helmholtz instability that results in the generation of eddy-like structures with characteristic length scales much larger than the organisms. The measured energy spectrum is consistent with these findings and indicates energy input at large scales, despite the small individual size of the organisms. These results motivate the study of biomixing in the presence of stratification to assess the contribution of migrating zooplankton to local and global ocean dynamics. The laser control methodology developed here enables systematic study of the relevant processes.

  7. Solar Observations with the Atacama Large Millimeter/submillimeter Array (ALMA)

    NASA Astrophysics Data System (ADS)

    Kobelski, A.; ALMA Solar Development Team

    2016-04-01

    The Atacama Large Millimeter/Submillimeter Array (ALMA) is a joint North American, European, and East Asian project that opens the mm-sub mm wavelength part of the electromagnetic spectrum for general astrophysical exploration, providing high-resolution imaging in frequency bands currently ranging from 84 GHz to 950 GHz (300 microns to 3 mm). It is located in the Atacama desert in northern Chile at an elevation of 5000 m. Despite being a general purpose instrument, provisions have been made to enable solar observations with ALMA. Radiation emitted at ALMA wavelengths originates mostly from the chromosphere, which plays an important role in the transport of matter and energy, and the in heating the outer layers of the solar atmosphere. Despite decades of research, the solar chromosphere remains a significant challenge: both to observe, owing to the complicated formation mechanisms of currently available diagnostics; and to understand, as a result of the complex nature of the structure and dynamics of the chromosphere. ALMA has the potential to change the scene substantially as it serves as a nearly linear thermometer at high spatial and temporal resolution, enabling us to study the complex interaction of magnetic fields and shock waves and yet-to-be-discovered dynamical processes. Moreover, ALMA will play an important role in the study of energetic emissions associated with solar flares at sub-THz frequencies.

  8. SEISMOLOGY OF A LARGE SOLAR CORONAL LOOP FROM EUVI/STEREO OBSERVATIONS OF ITS TRANSVERSE OSCILLATION

    SciTech Connect

    Verwichte, E.; Van Doorsselaere, T.; Foullon, C.; Nakariakov, V. M.; Aschwanden, M. J.

    2009-06-10

    The first analysis of a transverse loop oscillation observed by both Solar TErrestrial RElations Observatories (STEREO) spacecraft is presented, for an event on the 2007 June 27 as seen by the Extreme Ultraviolet Imager (EUVI). The three-dimensional loop geometry is determined using a three-dimensional reconstruction with a semicircular loop model, which allows for an accurate measurement of the loop length. The plane of wave polarization is found from comparison with a simulated loop model and shows that the oscillation is a fundamental horizontally polarized fast magnetoacoustic kink mode. The oscillation is characterized using an automated method and the results from both spacecraft are found to match closely. The oscillation period is 630 {+-} 30 s and the damping time is 1000 {+-} 300 s. Also, clear intensity variations associated with the transverse loop oscillations are reported for the first time. They are shown to be caused by the effect of line-of-sight integration. The Alfven speed and coronal magnetic field derived using coronal seismology are discussed. This study shows that EUVI/STEREO observations achieve an adequate accuracy for studying long-period, large-amplitude transverse loop oscillations.

  9. Microwave observations of late-type stars with the Very Large Array

    NASA Technical Reports Server (NTRS)

    Pallavicini, R.; Willson, R. F.; Lang, K. R.

    1985-01-01

    The Very Large Array was used to search for microwave emission from 32 stars of late spectral type including RS CVn type stars, dwarf M stars, and stars with active chromospheres, coronae, or intense magnetic fields. The RS CVn stars were detected at 6 cm wavelength, and upper limits are established for another six. Radio emission was detected from three dwarf M flare stars, UV Cet, EQ Peg and YZ CMi. Both impulsive (no more than 20 s) and more gradual (at least ten minutes) bursts were observed from the flare star YZ CMi. Radio emission was not confirmed at 6 cm from the solar type star Chi(1) Ori, with an upper limit that is three times lower than the detections reported by other observers. Microwave emission could not be detected from any other solar type star of spectral class F to K. The quiescent radio emission from dwarf M flare stars was interpreted as nonthermal gyrosynchrotron emission by mildly relativistic electrons accelerated more or less continuously in the magnetic fields of starspots.

  10. Deep view of the Large Magellanic Cloud with six years of Fermi-LAT observations

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Bloom, E. D.; Bonino, R.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Cohen-Tanugi, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Desiante, R.; Digel, S. W.; Drell, P. S.; Favuzzi, C.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Guillemot, L.; Guiriec, S.; Harding, A. K.; Hill, A. B.; Horan, D.; Jóhannesson, G.; Knödlseder, J.; Kuss, M.; Larsson, S.; Latronico, L.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lubrano, P.; Maldera, S.; Martin, P.; Mayer, M.; Mazziotta, M. N.; Michelson, P. F.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Murgia, S.; Nuss, E.; Ohsugi, T.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Romani, R. W.; Sánchez-Conde, M.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Spada, F.; Spandre, G.; Spinelli, P.; Suson, D. J.; Takahashi, H.; Thayer, J. B.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Troja, E.; Vianello, G.; Wood, M.; Zimmer, S.

    2016-02-01

    Context. The nearby Large Magellanic Cloud (LMC) provides a rare opportunity of a spatially resolved view of an external star-forming galaxy in γ-rays. The LMC was detected at 0.1-100 GeV as an extended source with CGRO/EGRET and using early observations with the Fermi-LAT. The emission was found to correlate with massive star-forming regions and to be particularly bright towards 30 Doradus. Aims: Studies of the origin and transport of cosmic rays (CRs) in the Milky Way are frequently hampered by line-of-sight confusion and poor distance determination. The LMC offers a complementary way to address these questions by revealing whether and how the γ-ray emission is connected to specific objects, populations of objects, and structures in the galaxy. Methods: We revisited the γ-ray emission from the LMC using about 73 months of Fermi-LAT P7REP data in the 0.2-100 GeV range. We developed a complete spatial and spectral model of the LMC emission, for which we tested several approaches: a simple geometrical description, template-fitting, and a physically driven model for CR-induced interstellar emission. Results: In addition to identifying PSR J0540-6919 through its pulsations, we find two hard sources positionally coincident with plerion N 157B and supernova remnant N 132D, which were also detected at TeV energies with H.E.S.S. We detect an additional soft source that is currently unidentified. Extended emission dominates the total flux from the LMC. It consists of an extended component of about the size of the galaxy and additional emission from three to four regions with degree-scale sizes. If it is interpreted as CRs interacting with interstellar gas, the large-scale emission implies a large-scale population of ~1-100 GeV CRs with a density of ~30% of the local Galactic value. On top of that, the three to four small-scale emission regions would correspond to enhancements of the CR density by factors 2 to 6 or higher, possibly more energetic and younger populations

  11. Observations of large earthquakes in the Mexican subduction zone over 110 years

    NASA Astrophysics Data System (ADS)

    Hjörleifsdóttir, Vala; Krishna Singh, Shri; Martínez-Peláez, Liliana; Garza-Girón, Ricardo; Lund, Björn; Ji, Chen

    2016-04-01

    Fault slip during an earthquake is observed to be highly heterogeneous, with areas of large slip interspersed with areas of smaller or even no slip. The cause of the heterogeneity is debated. One hypothesis is that the frictional properties on the fault are heterogeneous. The parts of the rupture surface that have large slip during earthquakes are coupled more strongly, whereas the areas in between and around creep continuously or episodically. The continuously or episodically creeping areas can partly release strain energy through aseismic slip during the interseismic period, resulting in relatively lower prestress than on the coupled areas. This would lead to subsequent earthquakes having large slip in the same place, or persistent asperities. A second hypothesis is that in the absence of creeping sections, the prestress is governed mainly by the accumulative stress change associated with previous earthquakes. Assuming homogeneous frictional properties on the fault, a larger prestress results in larger slip, i.e. the next earthquake may have large slip where there was little or no slip in the previous earthquake, which translates to non-persistent asperities. The study of earthquake cycles are hampered by short time period for which high quality, broadband seismological and accelerographic records, needed for detailed studies of slip distributions, are available. The earthquake cycle in the Mexican subduction zone is relatively short, with about 30 years between large events in many places. We are therefore entering a period for which we have good records for two subsequent events occurring in the same segment of the subduction zone. In this study we compare seismograms recorded either at the Wiechert seismograph or on a modern broadband seismometer located in Uppsala, Sweden for subsequent earthquakes in the Mexican subduction zone rupturing the same patch. The Wiechert seismograph is unique in the sense that it recorded continuously for more than 80 years

  12. GOSAT-OCO-2 synergetic CO2 observations over calibration & validation sites and large emission sources

    NASA Astrophysics Data System (ADS)

    Kuze, A.; Shiomi, K.; Suto, H.; Kataoka, F.; Crisp, D.; Schwandner, F. M.; Bruegge, C. J.; Taylor, T.; Kawakami, S.

    2015-12-01

    GOSAT and OCO-2 have different observation strategies. TANSO-FTS onboard GOSAT has wide spectral coverage from SWIR to TIR and an agile pointing system at the expense of spatial context, while OCO-2 targets CO2with higher spatial resolution using imaging grating spectrometers. Since the early phase of the two projects, both teams have worked in calibration and validation to demonstrate the effectiveness of satellite greenhouse gases observation. In 2008, the pre-launch cross-calibration agreement between GOSAT and OCO radiometers was better than 2% when measuring the traceable GOSAT calibration sphere (Sakuma et. al, 2010). Since GOSAT's launch in 2009, annual joint vicarious calibration campaigns at the Railroad Valley (RRV) playa have estimated radiometric degradation factors with time at an uncertainty of 7%. (Kuze et al., 2014). After OCO-2 launch, two independent measurements can now be compared to distinguish common forward calculation errors such as molecule absorption line parameters, solar lines and light-path modification by aerosol scattering from instrument-specific errors. On 25 Mach 2015, both GOSAT and OCO-2 targeted RRV simultaneously. The measured radiance spectra at the top of the atmosphere agree within 5% for all common bands. On June 29 and July 1 during the 7th RRV campaign, coincidence observation of GOSAT, OCO-2, AJAX airplane, radiosonde, and FTS and radiometers on the ground, provided surface albedo, BRDF, temperature, humidity CO2 and CH4 density to demonstrate consistency between forward radiative transfer calculation and satellite measured data. Both GOSAT and OCO-2 have been regularly targeting the TCCON site at Lamont and large emission sources such as mega cities and oil fields and glint over the ocean. Retrieved parameters such as surface albedo, pressure, column averaged mole fraction and aerosol related parameters can be compared firstly where aerosol optical thickness is low and topography is flat, and then over aerosol

  13. CLaMS-Ice: Large-scale cirrus cloud simulations in comparison with observations

    NASA Astrophysics Data System (ADS)

    Costa, Anja; Rolf, Christian; Grooß, Jens-Uwe; Spichtinger, Peter; Afchine, Armin; Spelten, Nicole; Dreiling, Volker; Zöger, Martin; Krämer, Martina

    2016-04-01

    Cirrus clouds are an element of uncertainty in the climate system and have received increasing attention since the last IPCC reports. The interactions of different freezing mechanisms, sedimentation rates, updraft velocity fluctuations and other factors that determine the formation and evolution of those clouds is still not fully understood. Thus, a reliable representation of cirrus clouds in models representing real atmospheric conditions is still a challenging task. At last year's EGU, Rolf et al. (2015) introduced the new large-scale microphysical cirrus cloud model CLaMS-Ice: based on trajectories calculated with CLaMS (McKenna et al., 2002 and Konopka et al. 2007), it simulates the development of cirrus clouds relying on the cirrus bulk model by Spichtinger and Gierens (2009). The qualitative agreement between CLaMS-Ice simulations and observations could be demonstrated at that time. Now we present a detailed quantitative comparison between standard ECMWF products, CLaMS-Ice simulations, and in-situ measurements obtained during the ML-Cirrus campaign 2014. We discuss the agreement of the parameters temperature (observational data: BAHAMAS), relative humidity (SHARC), cloud occurrence, cloud particle concentration, ice water content and cloud particle radii (all NIXE-CAPS). Due to the precise trajectories based on ECMWF wind and temperature fields, CLaMS-Ice represents the cirrus cloud vertical and horizontal coverage more accurately than the ECMWF ice water content (IWC) fields. We demonstrate how CLaMS-Ice can be used to evaluate different input settings (e.g. amount of ice nuclei, freezing thresholds, sedimentation settings) that lead to cirrus clouds with the microphysical properties observed during ML-Cirrus (2014).

  14. VERY LARGE ARRAY OH ZEEMAN OBSERVATIONS OF THE STAR-FORMING REGION S88B

    SciTech Connect

    Sarma, A. P.; Eftimova, M.; Brogan, C. L.; Bourke, T. L.; Troland, T. H.

    2013-04-10

    We present observations of the Zeeman effect in OH thermal absorption main lines at 1665 and 1667 MHz taken with the Very Large Array toward the star-forming region S88B. The OH absorption profiles toward this source are complicated, and contain several blended components toward a number of positions. Almost all of the OH absorbing gas is located in the eastern parts of S88B, toward the compact continuum source S88B-2 and the eastern parts of the extended continuum source S88B-1. The ratio of 1665/1667 MHz OH line intensities indicates the gas is likely highly clumped, in agreement with other molecular emission line observations in the literature. S88-B appears to present a similar geometry to the well-known star-forming region M17, in that there is an edge-on eastward progression from ionized to molecular gas. The detected magnetic fields appear to mirror this eastward transition; we detected line-of-sight magnetic fields ranging from 90 to 400 {mu}G, with the lowest values of the field to the southwest of the S88B-1 continuum peak, and the highest values to its northeast. We used the detected fields to assess the importance of the magnetic field in S88B by a number of methods; we calculated the ratio of thermal to magnetic pressures, we calculated the critical field necessary to completely support the cloud against self-gravity and compared it to the observed field, and we calculated the ratio of mass to magnetic flux in terms of the critical value of this parameter. All these methods indicated that the magnetic field in S88B is dynamically significant, and should provide an important source of support against gravity. Moreover, the magnetic energy density is in approximate equipartition with the turbulent energy density, again pointing to the importance of the magnetic field in this region.

  15. FIRST OBSERVATIONS OF A DOME-SHAPED LARGE-SCALE CORONAL EXTREME-ULTRAVIOLET WAVE

    SciTech Connect

    Veronig, A. M.; Muhr, N.; Kienreich, I. W.; Temmer, M.; Vrsnak, B.

    2010-06-10

    We present first observations of a dome-shaped large-scale extreme-ultraviolet coronal wave, recorded by the Extreme Ultraviolet Imager instrument on board STEREO-B on 2010 January 17. The main arguments that the observed structure is the wave dome (and not the coronal mass ejection, CME) are (1) the spherical form and sharpness of the dome's outer edge and the erupting CME loops observed inside the dome; (2) the low-coronal wave signatures above the limb perfectly connecting to the on-disk signatures of the wave; (3) the lateral extent of the expanding dome which is much larger than that of the coronal dimming; and (4) the associated high-frequency type II burst indicating shock formation low in the corona. The velocity of the upward expansion of the wave dome (v {approx} 650 km s{sup -1}) is larger than that of the lateral expansion of the wave (v {approx} 280 km s{sup -1}), indicating that the upward dome expansion is driven all the time, and thus depends on the CME speed, whereas in the lateral direction it is freely propagating after the CME lateral expansion stops. We also examine the evolution of the perturbation characteristics: first the perturbation profile steepens and the amplitude increases. Thereafter, the amplitude decreases with r {sup -2.5{+-}0.3}, the width broadens, and the integral below the perturbation remains constant. Our findings are consistent with the spherical expansion and decay of a weakly shocked fast-mode MHD wave.

  16. A Summary of Large Raindrop Observations from GPM GV Field Campaigns

    NASA Technical Reports Server (NTRS)

    Gatlin, Patrick N.; Petersen, Walter; Tokay, Ali; Thurai, Merhala; Bringi, V. N.; Carey, Lawrence; Wingo, Matthew

    2013-01-01

    NASA's Global Precipitation Measurement Mission (GPM) has conducted as series of Ground Validation (GV) studies to assist algorithm development for the GPM core satellite. Characterizing the drop size distribution (DSD) for different types of precipitation systems is critical in order to accurately estimate precipitation across the majority of the planet. Thus far, GV efforts have sampled DSDs in a variety of precipitation systems from Finland to Oklahoma. This dataset consists of over 33 million raindrops sampled by GPM GV's two-dimensional video disdrometers (2DVD) and includes RSD observations from the LPVEx, MC3E, GCPEx, HyMEx and IFloodS campaigns as well as from GV sites in Huntsville, AL and Wallops Island, VA. This study focuses on the larger end of the raindrop size spectrum, which greatly influences radar reflectivity and has implications for moment estimation. Thus knowledge of the maximum diameter is critical to GPM algorithm development. There are over 24,000 raindrops exceeding 5 mm in diameter contained within this disdrometer dataset. The largest raindrops in the 2DVD dataset (>7-8 mm in diameter) are found within intense convective thunderstorms, and their origins are believed to be hailstones. In stratiform rainfall, large raindrops have also been found to fall from lower and thicker melting layers. The 2DVD dataset will be combined with that collected by dual-polarimetric radar and aircraft particle imaging probes to "follow" the vertical evolution of the DSD tail (i.e., retrace the large drops from the surface to their origins aloft).

  17. Fermi Observations of Resolved Large-Scale Jets: Testing the IC/CMB Model

    NASA Astrophysics Data System (ADS)

    Breiding, Peter; Meyer, Eileen T.; Georganopoulos, Markos

    2017-01-01

    It has been observed with the Chandra X-ray Observatory since the early 2000s that many powerful quasar jets show X-ray emission on the kpc scale (Harris & Krawczynski, 2006). In many cases these X-rays cannot be explained by the extension of the radio-optical spectrum produced by synchrotron emitting electrons in the jet, since the observed X-ray flux is too high and the X-ray spectral index too hard. A widely accepted model for the X-ray emission first proposed by Celotti et al. 2001 and Tavecchio et al. 2000 posits that the X-rays are produced when relativistic electrons in the jet up-scatter ambient cosmic microwave background (CMB) photons via inverse Compton scattering from microwave to X-ray energies (the IC/CMB model). However, explaining the X-ray emission for these jets with the IC/CMB model requires high levels of IC/CMB γ-ray emission (Georganopoulos et al., 2006), which we are looking for using the FERMI/LAT γ-ray space telescope. Another viable model for the large scale jet X-ray emission favored by the results of Meyer et al. 2015 and Meyer & Georganopoulos 2014 is an alternate population of synchrotron emitting electrons. In contrast with the second synchrotron interpretation; the IC/CMB model requires jets with high kinetic powers which can exceed the Eddington luminsoity (Dermer & Atoyan 2004 and Atoyan & Dermer 2004) and be very fast on the kpc scale with a Γ~10 (Celotti et al. 2001 and Tavecchio et al. 2000). New results from data obtained with the Fermi/LAT will be shown for several quasars not in the Fermi/LAT 3FGL catalog whose large scale X-ray jets are attributed to IC/CMB. Additionally, recent work on the γ-ray bright blazar AP Librae will be shown which helps to constrain some models attempting to explain the high energy component of its SED, which extends from X-ray to TeV energies (e.g., Zacharias & Wagner 2016 & Petropoulou et al. 2016).

  18. Small Earth Observing Satellites Flying with Large Satellites in the A-Train

    NASA Technical Reports Server (NTRS)

    Kelly, Angelita C.; Loverro, Adam; Case, Warren F.; Queruel, Nadege; Marechal, Chistophe; Barroso, Therese

    2009-01-01

    This paper/poster presents a real-life example of the benefits of flying small satellites with other satellites, large or small, and vice versa. Typically, most small satellites fly payloads consisting of one or two instruments and fly in orbits that are independent from that of other satellites. The science data from these satellites are either used in isolation or correlated with instrument data from other satellites. Data correlation with other satellites is greatly improved when the measurements of the same point or air mass are taken at approximately the same time. Scientists worldwide are beginning to take advantage of the opportunities for improved data correlation, or coincidental science, offered by the international Earth Observing Constellation known as the A-Train (sometimes referred to as the Afternoon Constellation). Most of the A-Train satellites are small - the A-Train is anchored by two large NASA satellites (EOS-Aqua and EOS-Aura), but consists also of 5 small satellites (CloudSat, CALIPSO, PARASOL, OCO and Glory these last two will join in 2009). By flying in a constellation, each mission benefits from coincidental observations from instruments on the other satellites in the constellation. Essentially, from a data point of view, the A-Train can be envisioned as a single, virtual science platform with multiple instruments. Satellites in the A-Train fly at 705 km in sun-synchronous orbits. Their mean local times at the equator are within seconds to a few minutes of each other. This paper describes the challenges of operating an international constellation of independent satellites from the U.S. and Europe to maximize the coincidental science opportunities while at the same time minimizing the level of operational interactions required between team members. The A-Train mission teams have been able to demonstrate that flying as members of an international constellation does not take away the flexibility to accommodate new requirements. Specific

  19. Compact dual-band circular polarizer using twisted Hilbert-shaped chiral metamaterial.

    PubMed

    Xu, He-Xiu; Wang, Guang-Ming; Qi, Mei Qing; Cai, Tong; Cui, Tie Jun

    2013-10-21

    We propose a kind of chiral metamaterial inspired from the fractal concept. The Hilbert fractal perturbation in the twisted split ring resonator element results in compact metamaterial and breaking mirror symmetry, which readily forms chirality over triple bands. The discrepancy between co-polarization conversion and cross-polarization conversion over multiple bands can be explored for multifunctional devices. A multiband circular polarizer is then numerically and experimentally studied in the X band based on the bilayered twisted Hilbert resonator with mutual 90° rotation. The ability of transforming linearly polarized incident waves to circularly polarized waves is unambiguously demonstrated with high conversion efficiency and large polarization extinction ratio of more than 20 dB across dual bands. Moreover, exceptionally strong optical activity and circular dichroism are also observed.

  20. Transient Events in Archival Very Large Array Observations of the Galactic Center

    NASA Astrophysics Data System (ADS)

    Chiti, Anirudh; Chatterjee, Shami; Wharton, Robert; Cordes, James; Lazio, T. Joseph W.; Kaplan, David L.; Bower, Geoffrey C.; Croft, Steve

    2016-12-01

    The Galactic center has some of the highest stellar densities in the Galaxy and a range of interstellar scattering properties, which may aid in the detection of new radio-selected transient events. Here, we describe a search for radio transients in the Galactic center, using over 200 hr of archival data from the Very Large Array at 5 and 8.4 GHz. Every observation of Sgr A* from 1985 to 2005 has been searched using an automated processing and detection pipeline sensitive to transients with timescales between 30 s and 5 minutes with a typical detection threshold of ˜100 mJy. Eight possible candidates pass tests to filter false-positives from radio-frequency interference, calibration errors, and imaging artifacts. Two events are identified as promising candidates based on the smoothness of their light curves. Despite the high quality of their light curves, these detections remain suspect due to evidence of incomplete subtraction of the complex structure in the Galactic center, and apparent contingency of one detection on reduction routines. Events of this intensity (˜100 mJy) and duration (˜100 s) are not obviously associated with known astrophysical sources, and no counterparts are found in data at other wavelengths. We consider potential sources, including Galactic center pulsars, dwarf stars, sources like GCRT J1745-3009, and bursts from X-ray binaries. None can fully explain the observed transients, suggesting either a new astrophysical source or a subtle imaging artifact. More sensitive multiwavelength studies are necessary to characterize these events, which, if real, occur with a rate of {14}-12+32 {{hr}}-1 {\\deg }-2 in the Galactic center.

  1. Observational and Model Studies of Large-Scale Mixing Processes in the Stratosphere

    NASA Technical Reports Server (NTRS)

    Bowman, Kenneth P.

    1997-01-01

    The following is the final technical report for grant NAGW-3442, 'Observational and Model Studies of Large-Scale Mixing Processes in the Stratosphere'. Research efforts in the first year concentrated on transport and mixing processes in the polar vortices. Three papers on mixing in the Antarctic were published. The first was a numerical modeling study of wavebreaking and mixing and their relationship to the period of observed stratospheric waves (Bowman). The second paper presented evidence from TOMS for wavebreaking in the Antarctic (Bowman and Mangus 1993). The third paper used Lagrangian trajectory calculations from analyzed winds to show that there is very little transport into the Antarctic polar vortex prior to the vortex breakdown (Bowman). Mixing is significantly greater at lower levels. This research helped to confirm theoretical arguments for vortex isolation and data from the Antarctic field experiments that were interpreted as indicating isolation. A Ph.D. student, Steve Dahlberg, used the trajectory approach to investigate mixing and transport in the Arctic. While the Arctic vortex is much more disturbed than the Antarctic, there still appears to be relatively little transport across the vortex boundary at 450 K prior to the vortex breakdown. The primary reason for the absence of an ozone hole in the Arctic is the earlier warming and breakdown of the vortex compared to the Antarctic, not replenishment of ozone by greater transport. Two papers describing these results have appeared (Dahlberg and Bowman; Dahlberg and Bowman). Steve Dahlberg completed his Ph.D. thesis (Dahlberg and Bowman) and is now teaching in the Physics Department at Concordia College. We also prepared an analysis of the QBO in SBUV ozone data (Hollandsworth et al.). A numerical study in collaboration with Dr. Ping Chen investigated mixing by barotropic instability, which is the probable origin of the 4-day wave in the upper stratosphere (Bowman and Chen). The important result from

  2. Solar Observations with the Atacama Large Millimeter/submillimeter Array (ALMA)

    NASA Astrophysics Data System (ADS)

    Bastian, Timothy S.

    2015-04-01

    The Atacama Large Millimeter/Submillimeter Array (ALMA) is a joint North American, European, and East Asian project that opens the mm-submm wavelength part of the electromagnetic spectrum for general astrophysical exploration, providing high-resolution imaging in frequency bands currently ranging from 84 GHz to 950 GHz (300 microns to 3 mm). Despite being a general purpose instrument, provisions have been made to enable solar observations with ALMA. Radiation emitted at ALMA wavelengths originates mostly from the chromosphere, which plays an important role in the transport of matter and energy, and the in heating the outer layers of the solar atmosphere. Despite decades of research, the solar chromosphere remains a significant challenge: both to observe, owing to the complicated formation mechanisms of currently available diagnostics; and to understand, as a result of the complex nature of the structure and dynamics of the chromosphere. ALMA has the potential to change the scene substantially as it serves as a nearly linear thermometer at high spatial and temporal resolution, enabling us to study the complex interaction of magnetic fields and shock waves and yet-to-be-discovered dynamical processes. Moreover, ALMA will play an important role in the study of energetic emissions associated with solar flares at sub-THz frequencies.In this paper we describe recent efforts to ensure that ALMA can be usefully exploited by the scientific community to address outstanding questions in solar physics. We summarize activities by the ALMA solar development team comprised of scientists from the East Asia, North America, and Europe. These activities include instrument testing, development of calibration and imaging strategies, software requirements development, and science simulations. Opportunities for the wider community to contribute to these efforts will be highlighted.

  3. Riffle-pool maintenance and flow convergence routing observed on a large gravel-bed river

    NASA Astrophysics Data System (ADS)

    Sawyer, April M.; Pasternack, Gregory B.; Moir, Hamish J.; Fulton, Aaron A.

    2010-01-01

    Geomorphologists have studied and debated over the processes responsible for natural riffle-pool maintenance for decades. Most studies have focused on small wadable rivers, but they lack much description of overbank flood conditions or a spatially explicit characterization of morphodynamics. In this study, 1-m horizontal resolution digital elevation models were collected from a riffle-pool-run sequence before and after an overbank flood with a 7.7-year recurrence interval on the relatively large gravel-bed lower Yuba River, California. Digital elevation model differencing was used to quantify the magnitude and pattern of flood-induced morphodynamic change. Cross section based analysis and two-dimensional hydrodynamic modeling of flows ranging from 0.147 to 7.63 times bankful discharge were completed to evaluate the hydraulic mechanisms responsible for the observed topographic changes. One key finding was that riffle-pool relief increased by 0.42 m, confirming the occurrence of natural hydrogeomorphic maintenance. Spatially complex patterns of scour and deposition exceeding 0.15 m at the scale of subwidth morphological units were reasonably predicted by the two-dimensional mechanistic model that accounts for convective acceleration. The one-dimensional cross section based method underperformed the two-dimensional model significantly. Consequently, multiple scales of channel non-uniformity and a dynamic flow regime caused the observed maintenance of the pool-riffle morphology through the mechanism of "flow convergence routing" proposed by MacWilliams et al. [MacWilliams, M.L., Wheaton, J.M., Pasternack, G.B., Kitanidis, P.K., Street, R.L., 2006. The flow convergence-routing hypothesis for riffle-pool maintenance in alluvial rivers. Water Resources Research 42, W10427, doi:10.1029/2005WR004391].

  4. Constraints on Lorentz Invariance Violation from Fermi -Large Area Telescope Observations of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Vasileiou, V.; Jacholkowska, A.; Piron, F.; Bolmont, J.; Courturier, C.; Granot, J.; Stecker, Floyd William; Cohen-Tanugi, J.; Longo, F.

    2013-01-01

    We analyze the MeV/GeV emission from four bright Gamma-Ray Bursts (GRBs) observed by the Fermi-Large Area Telescope to produce robust, stringent constraints on a dependence of the speed of light in vacuo on the photon energy (vacuum dispersion), a form of Lorentz invariance violation (LIV) allowed by some Quantum Gravity (QG) theories. First, we use three different and complementary techniques to constrain the total degree of dispersion observed in the data. Additionally, using a maximally conservative set of assumptions on possible source-intrinsic spectral-evolution effects, we constrain any vacuum dispersion solely attributed to LIV. We then derive limits on the "QG energy scale" (the energy scale that LIV-inducing QG effects become important, E(sub QG)) and the coefficients of the Standard Model Extension. For the subluminal case (where high energy photons propagate more slowly than lower energy photons) and without taking into account any source-intrinsic dispersion, our most stringent limits (at 95% CL) are obtained from GRB 090510 and are E(sub QG,1) > 7.6 times the Planck energy (E(sub Pl)) and E(sub QG,2) > 1.3×10(exp 11) GeV for linear and quadratic leading order LIV-induced vacuum dispersion, respectively. These limits improve the latest constraints by Fermi and H.E.S.S. by a factor of approx. 2. Our results disfavor any class of models requiring E(sub QG,1) < or approx. E(sub Pl)

  5. The Potential of Time Series Based Earth Observation for the Monitoring of Large River Deltas

    NASA Astrophysics Data System (ADS)

    Kuenzer, C.; Leinenkugel, P.; Huth, J.; Ottinger, M.; Renaud, F.; Foufoula-Georgiou, E.; Vo Khac, T.; Trinh Thi, L.; Dech, S.; Koch, P.; Le Tissier, M.

    2015-12-01

    Although river deltas only contribute 5% to the overall land surface, nearly six hundred million people live in these complex social-ecological environments, which combine a variety of appealing locational advantages. In many countries deltas provide the major national contribution to agricultural and industrial production. At the same time these already very dynamic environments are exposed to a variety of threats, including the disturbance and replacement of valuable ecosystems, increasing water, soil, and air pollution, human induced land subsidence, sea level rise, as well upstream developments impacting water and sediment supplies. A constant monitoring of delta systems is thus of utmost relevance for understanding past and current land surface change and anticipating possible future developments. We present the potential of Earth Observation based analyses and derived novel information products that can play a key role in this context. Along with the current trend of opening up numerous satellite data archives go increasing capabilities to explore big data. Whereas in past decades remote sensing data were analysed based on the spectral-reflectance-defined 'finger print' of individual surfaces, we mainly exploit the 'temporal fingerprints' of our land surface in novel pathways of data analyses at differing spatial-, and temporally-dense scales. Following our results on an Earth Observation based characterization of large deltas globally, we present in depth results from the Mekong Delta in Vietnam, the Yellow River Delta in China, the Niger Delta in Nigeria, as well as additional deltas, focussing on the assessment of river delta flood and inundation dynamics, river delta coastline dynamics, delta morphology dynamics including the quantification of erosion and accretion processes, river delta land use change and trends, as well as the monitoring of compliance to environmental regulations.

  6. A potential large and persistent black carbon forcing over Northern Pacific inferred from satellite observations

    NASA Astrophysics Data System (ADS)

    Li, Zhongshu; Liu, Junfeng; Mauzerall, Denise L.; Li, Xiaoyuan; Fan, Songmiao; Horowitz, Larry W.; He, Cenlin; Yi, Kan; Tao, Shu

    2017-03-01

    Black carbon (BC) aerosol strongly absorbs solar radiation, which warms climate. However, accurate estimation of BC’s climate effect is limited by the uncertainties of its spatiotemporal distribution, especially over remote oceanic areas. The HIAPER Pole-to-Pole Observation (HIPPO) program from 2009 to 2011 intercepted multiple snapshots of BC profiles over Pacific in various seasons, and revealed a 2 to 5 times overestimate of BC by current global models. In this study, we compared the measurements from aircraft campaigns and satellites, and found a robust association between BC concentrations and satellite-retrieved CO, tropospheric NO2, and aerosol optical depth (AOD) (R2 > 0.8). This establishes a basis to construct a satellite-based column BC approximation (sBC*) over remote oceans. The inferred sBC* shows that Asian outflows in spring bring much more BC aerosols to the mid-Pacific than those occurring in other seasons. In addition, inter-annual variability of sBC* is seen over the Northern Pacific, with abundances varying consistently with the springtime Pacific/North American (PNA) index. Our sBC* dataset infers a widespread overestimation of BC loadings and BC Direct Radiative Forcing by current models over North Pacific, which further suggests that large uncertainties exist on aerosol-climate interactions over other remote oceanic areas beyond Pacific.

  7. Observations of ground-state OH in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Brooks, K. J.; Whiteoak, J. B.

    1997-11-01

    We have carried out a series of observations of the 1665- and 1667-MHz transitions of the 2Pi3/2, J = 3/2 OH ground state towards six selected H II regions in the Large Magellanic Cloud (IRAS 05011-6815 and MRC 0510-689, 0513-694B, 0539-691, 0540-696B, 0540-697A) using the Australia Telescope Compact Array. The study has provided the first accurate positions for known 1665- and 1667-MHz OH masers as well as detecting several new masers. The regions all contain H2O or CH3OH masers but OH masers were detected in only four. The 1.6-GHz continuum emission was also imaged to investigate its spatial relationship to the associated OH maser. Although some masers are close to compact continuum components, in other cases they are near the continuum distribution boundaries and perhaps have been created as a result of the H II region interacting with the surrounding interstellar medium.

  8. Interplanetary Scintillation Observations of the Large-Scale Structure of the Solar Wind Using EISCAT

    NASA Astrophysics Data System (ADS)

    Bisi, M. M.; Breen, A. R.; Habbal, S. R.; Fallows, R. A.

    2004-12-01

    Measurements of interplanetary scintillation (IPS) taken with the European Incoherent SCATter radar (EISCAT) in northern Scandinavia can be used to study the evolution of the solar wind as it expands through interplanetary space. IPS arises from changes in the apparent brightness of distant, compact radio sources due to scattering by density irregularities in the solar wind and can be used to obtain estimates of the solar wind speed. In this paper we present the results of a study of the large-scale structure of the fast solar wind under near solar minimum conditions, using data taken with the EISCAT system, and the extremely long baseline observations which combine the EISCAT and MERLIN systems. The latter are the best measurements to date of meridional components of velocity in the inner solar wind. In particular, the existence of a gradient in solar wind velocity of the fast wind over the polar crown, at latitudes corresponding to the x-ray and ultra-violet coronal hole boundary, as reported by Habbal and Woo (2001), is also explored.

  9. Observations of short large-amplitude magnetic structures at a quasi-parallel shock

    NASA Technical Reports Server (NTRS)

    Schwartz, Steven J.; Burgess, David; Wilkinson, William P.; Kessel, Ramona L.; Dunlop, Malcolm; Luehr, Herman

    1992-01-01

    Results of a detailed analysis of short large-amplitude magnetic structures (SLAMS) observed at an encounter of the quasi-parallel blow shock by the AMPTE UKS and IRM satellites are presented. Isolated SLAMS, surrounded by solar wind conditions, and embedded SLAMS, which lie within or form the boundary with regions of significant heating and deceleration, are identified. The duration, polarization, and other characteristics of SLAMS are all consistent with their growth directly out of the ULF wave field, including the common occurrence of an attached whistler as found in ULF shocklets. The plasma rest frame propagation speeds and two-spacecraft time delays for all cases show that the SLAMS attempt to propagate upstream against the oncoming flow, but are convected back downstream. The speeds and delays vary systematically with SLAMS amplitude in the way anticipated from nonlinear wave theory, as do their polarization features. Inter-SLAMS regions and boundary regions with solar wind contain hot deflected ions of lesser density than within the SLAMS.

  10. A potential large and persistent black carbon forcing over Northern Pacific inferred from satellite observations.

    PubMed

    Li, Zhongshu; Liu, Junfeng; Mauzerall, Denise L; Li, Xiaoyuan; Fan, Songmiao; Horowitz, Larry W; He, Cenlin; Yi, Kan; Tao, Shu

    2017-03-07

    Black carbon (BC) aerosol strongly absorbs solar radiation, which warms climate. However, accurate estimation of BC's climate effect is limited by the uncertainties of its spatiotemporal distribution, especially over remote oceanic areas. The HIAPER Pole-to-Pole Observation (HIPPO) program from 2009 to 2011 intercepted multiple snapshots of BC profiles over Pacific in various seasons, and revealed a 2 to 5 times overestimate of BC by current global models. In this study, we compared the measurements from aircraft campaigns and satellites, and found a robust association between BC concentrations and satellite-retrieved CO, tropospheric NO2, and aerosol optical depth (AOD) (R(2) > 0.8). This establishes a basis to construct a satellite-based column BC approximation (sBC*) over remote oceans. The inferred sBC* shows that Asian outflows in spring bring much more BC aerosols to the mid-Pacific than those occurring in other seasons. In addition, inter-annual variability of sBC* is seen over the Northern Pacific, with abundances varying consistently with the springtime Pacific/North American (PNA) index. Our sBC* dataset infers a widespread overestimation of BC loadings and BC Direct Radiative Forcing by current models over North Pacific, which further suggests that large uncertainties exist on aerosol-climate interactions over other remote oceanic areas beyond Pacific.

  11. WFPC2 observations of the double cluster NGC 1850 in the Large Magellanic Cloud

    NASA Technical Reports Server (NTRS)

    Gilmozzi, R.; Kinney, E. K.; Ewald, S. P.; Panagia, N.; Romaniello, M.

    1994-01-01

    Hubble Space Telescope-Wide Field/Planetary Camera-2 (HST-WFPC2) optical and ultraviolet imaging observations of the young double cluster NGC 1850 in the Large Magellanic Cloud (LMC) are presented. The main cluster, NGC 1850A, is a globular-like cluster and has an age of 50 +/- 10 Myr, while the subcluster, NGC 1850B, which is more loosely distributed, is very young at 4.3 +/- 0.9 Myr. Its young age is confirmed by the detection of a pre-main-sequence population of stars associated to it. The two clusters have considerably different IMF slopes, with the main cluster having a flat slope (f(m) proportional to m(exp -1.4 +/- 0.2)) and the young cluster a much steeper one (f(m) proportional to m(exp -2.6 +/- -0.1)). The LMC field star population displays a broad range of ages, from approximately 0.5 Gyr up to more than 4 Gyr.

  12. Search for Large Extra Dimensions Based on Observations of Neutron Stars with the Fermi-LAT

    SciTech Connect

    Berenji, Bijan

    2012-09-19

    Large extra dimensions (LED) have been proposed to account for the apparent weakness of gravitation. These theories also indicate that the postulated massive Kaluza-Klein (KK) gravitons may be produced by nucleon-nucleon bremsstrahlung in the course of core collapse of supernovae. Hannestad and Raffelt have predicted energy spectra of gamma ray emission from the decay of KK gravitons trapped by the gravity of the remnant neutron stars (NS). These and other authors have used EGRET data on NS to obtain stringent limits on LED. Fermi-LAT is observing radio pulsar positions obtained from radio and x-ray catalogs. NS with certain characteristics are unlikely emitter of gamma rays, and emit in radio and perhaps x-rays. This talk will focus on the blind analysis we plan to perform, which has been developed using the 1st 2 months of all sky data and Monte Carlo simulations, to obtain limits on LED based on about 1 year of Fermi-LAT data. Preliminary limits from this analysis using these first 2 months of data will be also be discussed.

  13. How do We Choose, Use and Interpret Data From Large Scale Observing Arrays?

    NASA Astrophysics Data System (ADS)

    Thiebaux, H.

    2005-12-01

    This is a poster presentation of a "website under construction" that will provide free-ware access to spatial analysis modules for Kalman Filtering, Kriging, Neural Networks, Splines, Empirical Orthogonal Function Analysis, and Spatial Objective Analysis. The website is being designed to aid scientists, educators and students with the analysis of data which is generally sparse and irregularly spaced, for which the geographic locations of the observing points are essential inputs to the analyses. Sections for each of the state-of-the-art methodologies will include: 1) Discussion of the objectives for which it was originally developed; 2) Examples of applications to large data sets; 3) Mathematical foundations; 4) References to relevant scientific and mathematical literature; 5) E-links to software for data analysis, with explanations for its use; 6) E-links to data sets for exercise of the technology. Modular construction will permit use of any of the above technologies, independent of others. This "workshop presentation" invites creative input that can contribute to the utility of the final product, from all viewers/potential users.

  14. A potential large and persistent black carbon forcing over Northern Pacific inferred from satellite observations

    PubMed Central

    Li, Zhongshu; Liu, Junfeng; Mauzerall, Denise L.; Li, Xiaoyuan; Fan, Songmiao; Horowitz, Larry W.; He, Cenlin; Yi, Kan; Tao, Shu

    2017-01-01

    Black carbon (BC) aerosol strongly absorbs solar radiation, which warms climate. However, accurate estimation of BC’s climate effect is limited by the uncertainties of its spatiotemporal distribution, especially over remote oceanic areas. The HIAPER Pole-to-Pole Observation (HIPPO) program from 2009 to 2011 intercepted multiple snapshots of BC profiles over Pacific in various seasons, and revealed a 2 to 5 times overestimate of BC by current global models. In this study, we compared the measurements from aircraft campaigns and satellites, and found a robust association between BC concentrations and satellite-retrieved CO, tropospheric NO2, and aerosol optical depth (AOD) (R2 > 0.8). This establishes a basis to construct a satellite-based column BC approximation (sBC*) over remote oceans. The inferred sBC* shows that Asian outflows in spring bring much more BC aerosols to the mid-Pacific than those occurring in other seasons. In addition, inter-annual variability of sBC* is seen over the Northern Pacific, with abundances varying consistently with the springtime Pacific/North American (PNA) index. Our sBC* dataset infers a widespread overestimation of BC loadings and BC Direct Radiative Forcing by current models over North Pacific, which further suggests that large uncertainties exist on aerosol-climate interactions over other remote oceanic areas beyond Pacific. PMID:28266532

  15. Galaxy evolution and large-scale structure in the far-infrared. I. IRAS pointed observations

    SciTech Connect

    Lonsdale, C.J.; Hacking, P.B.

    1989-04-01

    Redshifts for 66 galaxies were obtained from a sample of 93 60-micron sources detected serendipitously in 22 IRAS deep pointed observations, covering a total area of 18.4 sq deg. The flux density limit of this survey is 150 mJy, 4 times fainter than the IRAS Point Source Catalog (PSC). The luminosity function is similar in shape with those previously published for samples selected from the PSC, with a median redshift of 0.048 for the fainter sample, but shifted to higher space densities. There is evidence that some of the excess number counts in the deeper sample can be explained in terms of a large-scale density enhancement beyond the Pavo-Indus supercluster. In addition, the faintest counts in the new sample confirm the result of Hacking et al. (1989) that faint IRAS 60-micron source counts lie significantly in excess of an extrapolation of the PSC counts assuming no luminosity or density evolution. 81 refs.

  16. Observed and Aogcm Simulated Relationships Between us Wind Speeds and Large Scale Modes of Climate Variability

    NASA Astrophysics Data System (ADS)

    Schoof, J. T.; Pryor, S. C.; Barthelmie, R. J.

    2013-12-01

    Previous research has indicated that large-scale modes of climate variability, such as El Niño - Southern Oscillation (ENSO), the Arctic Oscillation (AO) and the Pacific-North American pattern (PNA), influence the inter-annual and intra-annual variability of near-surface and upper-level wind speeds over the United States. For example, we have shown that rawinsonde derived wind speeds indicate that 90th percentile of wind speeds at 700 hPa over the Pacific Northwest and Southwestern USA are significantly higher under the negative phase of the PNA, and the Central Plains experiences higher wind speeds at 850 hPa under positive phase Southern Oscillation index while the Northeast exhibits higher wind speeds at 850 hPa under positive phase NAO. Here, we extend this research by further investigating these relationships using both reanalysis products and output from coupled atmosphere-ocean general circulation models (AOGCMs) developed for the 5th Phase of the Coupled Model Intercomparison Project (CMIP5). The research presented has two specific goals. First, we evaluate the AOGCM simulations in terms of their ability to represent the temporal and spatial representations of ENSO, the AO, and the PNA pattern relative to historical observations. The diagnostics used include calculation of the power spectra (and thus representation of the fundamental frequencies of variability) and Taylor diagrams (for comparative assessment of the spatial patterns and their intensities). Our initial results indicate that most AOGCMs produce modes that are qualitatively similar to those observed, but that differ slightly in terms of the spatial pattern, intensity of specific centers of action, and variance explained. Figure 1 illustrates an example of the analysis of the frequencies of variability of two climate modes for the NCEP-NCAR reanalysis (NNR) and a single AOGCM (BCC CSM1). The results show a high degree of similarity in the power spectra but for this AOGCM the variance of the PNA

  17. Felyx : A Free Open Software Solution for the Analysis of Large Earth Observation Datasets

    NASA Astrophysics Data System (ADS)

    Piolle, Jean-Francois; Shutler, Jamie; Poulter, David; Guidetti, Veronica; Donlon, Craig

    2014-05-01

    GHRSST project, by assembling large collections of earth observation data from various sources and agencies, has also raised the need for providing the user community with tools to inter-compare them, assess and monitor their quality. The ESA /Medspiration project, which implemented the first operating node of GHRSST system for Europe, also paved the way successfully towards such generic analytics tools by developing the High Resolution Diagnostic Dataset System (HR-DDS) and Satellite to In situ Multi-sensor Match-up Databases. Building on this heritage, ESA is now funding the development by IFREMER, PML and Pelamis of felyx, a web tool merging the two capabilities into a single software solution. It will consist in a free open software solution, written in python and javascript, whose aim is to provide Earth Observation data producers and users with an open-source, flexible and reusable tool to allow the quality and performance of data streams (satellite, in situ and model) to be easily monitored and studied. The primary concept of Felyx is to work as an extraction tool, subsetting source data over predefined target areas (which can be static or moving) : these data subsets, and associated metrics, can then be accessed by users or client applications either as raw files, automatic alerts and reports generated periodically, or through a flexible web interface enabling statistical analysis and visualization. Felyx presents itself as an open-source suite of tools, written in python and javascript, enabling : * subsetting large local or remote collections of Earth Observation data over predefined sites (geographical boxes) or moving targets (ship, buoy, hurricane), storing locally the extracted data (refered as miniProds). These miniProds constitute a much smaller representative subset of the original collection on which one can perform any kind of processing or assessment without having to cope with heavy volumes of data. * computing statistical metrics over these

  18. Charged Particle Optics in Circular Higgs Factory

    SciTech Connect

    Cai, Yunhai

    2015-02-26

    Similar to a super B-factory, a circular Higgs factory will require strong focusing systems near the interaction points and a low-emittance lattice in arcs to achieve a factory luminosity. At electron beam energy of 120 GeV, beamstrahlung effects during the collision pose an additional challenge to the collider design. In particular, a large momentum acceptance at 2 percent level is necessary to retain an adequate beam lifetime. This turns out to be the most challenging aspect in the design of circular Higgs factory. In this paper, an example will be provided to illustrate the beam dynamics in circular Higgs factory, emphasizing on the chromatic optics. Basic optical modules and advanced analysis will be presented. Most important, we will show that 2% momentum aperture is achievable

  19. Very Large Array Observations of the Sun with Related Observations Using the SMM (Solar Maximum Mission) Satellite

    DTIC Science & Technology

    1988-10-12

    1987)....233 28. "Multiple Wavelength lfcrowave Observations of the RS Canum Venaticorum Stars UX Arietis, HR 1099, HR 5110 and II Pegasi ", Robert F...therefore remain un- 0 103 ,resolved even with the V.L.A.; but the two components of the binary system EQ Pegasi have been detected (Topka and Marsh... ll Single coronal loops or arcades oi loops often begin to near up and cnange structure ao0uC 3- minutes before cne eruption of impulsive bursts. -Uny

  20. Observations and Large-Eddy Simulations of Wave-Induced Boundary-Layer Separation

    NASA Astrophysics Data System (ADS)

    Grubisic, V.; Serafin, S.; Strauss, L.

    2011-12-01

    Wave-induced boundary-layer separation in flow over orography has received significant attention in recent years, especially in relation to the formation of atmospheric rotors. Traditionally depicted as horizontal eddies in the lee of mountain ranges, rotors are characterized by intense turbulence and pose a known threat to aviation. This study focuses on the first observationally documented case of wave-induced boundary-layer separation, which occurred on Jan 26 2006 in the lee of the Medicine Bow Mountains in SE Wyoming. Observations from the University of Wyoming King Air (UWKA) aircraft, in particular, the remote sensing measurements with the dual-Doppler Wyoming Cloud Radar (WCR), indicate strong wave activity, downslope winds in excess of 30 m s-1 within 200 m above the ground, and near-surface flow reversal in the lee of the mountain range. The fine resolution of WCR data (on the order of 40x40 m2 for two-dimensional velocity fields) reveals fine-scale coherent vortical structures which are embedded within the rotor zone and whose intensity contributes to the severity of turbulence therein. A series of semi-idealized three-dimensional large-eddy simulations of the Medicine Bow case was carried out using the CM1 model. Simulations represent the flow of an air mass with invariant profiles of wind speed and potential temperature over an isolated mountain ridge: the atmospheric soundings match the available observations and the ridge has the same size and shape as the Medicine Bow range. Model runs consider a simplified two-dimensional geometry where the complex topographic obstacle is represented as a smooth linear mountain ridge, but they are fully three-dimensional allowing for realistic turbulence dynamics. The simulated flow field is strikingly similar to the observed, with the simulations reproducing strong downslope flow detaching from the ground, with a patch of considerably lower wind intensities and embedded reverse flow further downstream. The near

  1. 78 FR 14620 - Joint Development: Proposed Circular

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-06

    ... Federal Transit Administration Joint Development: Proposed Circular AGENCY: Federal Transit Administration... the form of a circular, on joint development. This circular provides guidance to recipients of Federal... joint development. This circular: (1) Defines the term ``joint development''; ] (2) explains how...

  2. FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE CRAB PULSAR AND NEBULA

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Baring, M. G.; Bastieri, D.; Bonamente, E.; Brigida, M. E-mail: mazziotta@ba.infn.i E-mail: lemoine@cenbg.in2p3.f

    2010-01-10

    We report on gamma-ray observations of the Crab Pulsar and Nebula using 8 months of survey data with the Fermi Large Area Telescope (LAT). The high quality light curve obtained using the ephemeris provided by the Nancay and Jodrell Bank radio telescopes shows two main peaks stable in phase with energy. The first gamma-ray peak leads the radio main pulse by (281 +- 12 +- 21) mus, giving new constraints on the production site of non-thermal emission in pulsar magnetospheres. The first uncertainty is due to gamma-ray statistics, and the second arises from the rotation parameters. The improved sensitivity and the unprecedented statistics afforded by the LAT enable precise measurement of the Crab Pulsar spectral parameters: cut-off energy at E{sub c} = (5.8 +- 0.5 +- 1.2) GeV, spectral index of GAMMA = (1.97 +- 0.02 +- 0.06) and integral photon flux above 100 MeV of (2.09 +- 0.03 +- 0.18) x 10{sup -6} cm{sup -2} s{sup -1}. The first errors represent the statistical error on the fit parameters, while the second ones are the systematic uncertainties. Pulsed gamma-ray photons are observed up to approx 20 GeV which precludes emission near the stellar surface, below altitudes of around 4-5 stellar radii in phase intervals encompassing the two main peaks. A detailed phase-resolved spectral analysis is also performed: the hardest emission from the Crab Pulsar comes from the bridge region between the two gamma-ray peaks while the softest comes from the falling edge of the second peak. The spectrum of the nebula in the energy range 100 MeV-300 GeV is well described by the sum of two power laws of indices GAMMA{sub sync} = (3.99 +- 0.12 +- 0.08) and GAMMA{sub IC} = (1.64 +- 0.05 +- 0.07), corresponding to the falling edge of the synchrotron and the rising edge of the inverse Compton (IC) components, respectively. This latter, which links up naturally with the spectral data points of Cherenkov experiments, is well reproduced via IC scattering from standard magnetohydrodynamic

  3. XMM-Newton observation of SNR J0533-7202 in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Kavanagh, P. J.; Sasaki, M.; Whelan, E. T.; Maggi, P.; Haberl, F.; Bozzetto, L. M.; Filipović, M. D.; Crawford, E. J.

    2015-07-01

    Aims: We present an X-ray study of the supernova remnant SNR J0533-7202 in the Large Magellanic Cloud (LMC) and determine its physical characteristics based on its X-ray emission. Methods: We observed SNR J0533-7202 with XMM-Newton (background flare-filtered exposure times of 18 ks EPIC-pn and 31 ks EPIC-MOS1, EPIC-MOS2). We produced X-ray images of the supernova remnant, performed an X-ray spectral analysis, and compared the results to multi-wavelength studies. Results: The distribution of X-ray emission is highly non-uniform, with the south-west region much brighter than the north-east. The detected X-ray emission is correlated with the radio emission from the remnant. We determine that this morphology is most likely due to the supernova remnant expanding into a non-uniform ambient medium and not an absorption effect. We estimate the remnant size to be 53.9 (±3.4) × 43.6 (±3.4) pc, with the major axis rotated ~64° east of north. We find no spectral signatures of ejecta emission and infer that the X-ray plasma is dominated by swept up interstellar medium. Using the spectral fit results and the Sedov self-similar solution, we estimate the age of SNR J0533-7202 to be ~17-27 kyr, with an initial explosion energy of (0.09-0.83) × 1051 erg. We detected an X-ray source located near the centre of the remnant, namely XMMU J053348.2-720233. The source type could not be conclusively determined due to the lack of a multi-wavelength counterpart and low X-ray counts. We found that it is likely either a background active galactic nucleus or a low-mass X-ray binary in the LMC. Conclusions: We detected bright thermal X-ray emission from SNR J0533-7202 and determined that the remnant is in the Sedov phase of its evolution. The lack of ejecta emission prohibits us from typing the remnant with the X-ray data. Therefore, the likely Type Ia classification based on the local stellar population and star formation history reported in the literature cannot be improved upon. Based on

  4. Z-DNA: vacuum ultraviolet circular dichroism

    SciTech Connect

    Sutherland, J.C.; Griffin, K.P.; Keck, P.C.; Takacs, P.Z.

    1981-08-01

    In concentrated salt or ethanolic solutions, the self-complementary copolymer poly(dG-dC)-poly(dG-dC) forms a left-handed double-helical structure that has been termed Z-DNA. The first evidence for this structure came from changes observed in the circular dichroism (CD) spectrum between 230 and 300 nm for low- and high-salt solutions. In 3 M NaCl, the CD spectrum is approximately inverted compared to the B-form spectrum observed in low salt solution. We measured the vacuum ultraviolet CD spectrum of poly(dG-dC)-poly(dG-dC) down to 180 nm under conditions in which the 230- to 300-nm spectrum is inverted. Below 200 nm, where the B form exhibits the large positive peak at 187 nm that is characteristic of right-handed double-helical DNAs, the Z form exhibits a large negative peak at 194 nm and a positive band below 186 nm. Therefore, the Z-form vacuum ultraviolet CD spectrum resembles an inverted and red-shifted B-form spectrum. The magnitudes of the differences observed between the B and Z forms in the CD spectrum below 200 nm are about 10 times greater than those observed between 230 and 300 nm. The vacuum ultraviolet CD spectrum of poly(dG-dC)-poly(dG-dC) is 3 M C/sub 2/O/sub 4/ also is inverted compared to the B-form spectrum; however, between 230 and 300 nm, it is nonconservative with a negative maximum at 290 nm and a weak positive CD signal above 300 nm, presumably reflecting differential light scattering and indicating the existence of molecular aggregates. Our results suggest that the vacuum ultraviolet CD spectrum is sensitive to the handedness of doublehelical DNA structures.

  5. Z-DNA Vacuum ultraviolet circular dichroism

    SciTech Connect

    Sutherland, J.C.; Griffin, K.P.; Keck, P.C.; Takacs, P.Z.

    1981-08-01

    In concentrated salt or ethanolic solutions, the self-complementary copolymer poly(dG-dC).poly(dG-dC) forms a left-handed double-helical structure that has been termed ZDNA. The first evidence for this structure came from changes observed in the circular dichroism (CD) spectrum between 230 and 300 nm for low- and high-salt solutions (Pohl, F.M. and Jovin, T.M. (1972) J. Mol. Biol. 67, 675-696). In 3 M NaCl, the CD spectrum is approximately inverted compared to the B-form spectrum observed in low-salt solution. We measured the vacuum ultraviolet CD spectrum of poly(dG-dC).poly(dG-dC) down to 180 nm under conditions in which the 230 to 300 nm spectrum is inverted. Below 200 nm, where the B form exhibits the large positive peak at 187 nm that is characteristic of right-handed double-helical DNAs, the Z form exhibits a large negative peak at 194 nm and a positive band below 186 nm. Therefore, the Z-form vacuum ultraviolet CD spectrum resembles an inverted and red-shifted B-form spectrum. The magnitudes of the differences observed between the Band Z forms in the CD spectrum below 200 nm are about 10 times greater than those observed between 230 and 300 nm. The vacuum ultraviolet CD spectrum of poly(dG-dC).poly(dG-dC) in 3 M Cs/sub 2/SO/sub 4/ also is inverted compared to the B-form spectrum; however, between 230 and 300 nm, it is nonconservative with a negative maximum at 290 nm and a weak positive CD signal above 300 nm, presumably reflecting differential light scattering and indicating the existence of molecular aggregates. Our results suggest that the vacuum ultraviolet CD spectrum is sensitive to the handedness of double-helical DNA structures.

  6. Geological observations on large earthquakes along the Himalayan frontal fault near Kathmandu, Nepal

    NASA Astrophysics Data System (ADS)

    Wesnousky, Steven G.; Kumahara, Yasuhiro; Chamlagain, Deepak; Pierce, Ian K.; Karki, Alina; Gautam, Dipendra

    2017-01-01

    The 2015 Gorkha earthquake produced displacement on the lower half of a shallow decollement that extends 100 km south, and upward from beneath the High Himalaya and Kathmandu to where it breaks the surface to form the trace of the Himalayan Frontal Thrust (HFT), leaving unruptured the shallowest ∼50 km of the decollement. To address the potential of future earthquakes along this section of the HFT, we examine structural, stratigraphic, and radiocarbon relationships in exposures created by emplacement of trenches across the HFT where it has produced scarps in young alluvium at the mouths of major rivers at Tribeni and Bagmati. The Bagmati site is located south of Kathmandu and directly up dip from the Gorkha rupture, whereas the Tribeni site is located ∼200 km to the west and outside the up dip projection of the Gorkha earthquake rupture plane. The most recent rupture at Tribeni occurred 1221-1262 AD to produce a scarp of ∼7 m vertical separation. Vertical separation across the scarp at Bagmati registers ∼10 m, possibly greater, and formed between 1031-1321 AD. The temporal constraints and large displacements allow the interpretation that the two sites separated by ∼200 km each ruptured simultaneously, possibly during 1255 AD, the year of a historically reported earthquake that produced damage in Kathmandu. In light of geodetic data that show ∼20 mm/yr of crustal shortening is occurring across the Himalayan front, the sum of observations is interpreted to suggest that the HFT extending from Tribeni to Bagmati may rupture simultaneously, that the next great earthquake near Kathmandu may rupture an area significantly greater than the section of HFT up dip from the Gorkha earthquake, and that it is prudent to consider that the HFT near Kathmandu is well along in a strain accumulation cycle prior to a great thrust earthquake, most likely much greater than occurred in 2015.

  7. Very Large Array Observations of Ammonia in High-mass Star Formation Regions

    NASA Astrophysics Data System (ADS)

    Lu, Xing; Zhang, Qizhou; Liu, Hauyu Baobab; Wang, Junzhi; Gu, Qiusheng

    2014-08-01

    We report systematic mapping observations of the NH3 (1, 1) and (2, 2) inversion lines toward 62 high-mass star-forming regions using the Very Large Array (VLA) in its D and DnC array configurations. The VLA images cover a spatial dynamic range from 40'' to 3'', allowing us to trace gas kinematics from ~1 pc scales to lsim0.1 pc scales. Based on the NH3 morphology and the infrared nebulosity on 1 pc scales, we categorize three subclasses in the sample: filaments, hot cores, and NH3-dispersed sources. The ubiquitous gas filaments found on 1 pc scales have a typical width of ~0.1 pc and often contain regularly spaced fragments along the major axis. The spacing of the fragments and the column densities is consistent with the turbulent supported fragmentation of cylinders. Several sources show multiple filaments that converge toward a center where the velocity field in the filaments is consistent with gas flows. We derive rotational temperature maps for the entire sample. For the three hot core sources, we find a projected radial temperature distribution that is best fit by power-law indices from -0.18 to -0.35. We identify 174 velocity-coherent ~0.1 pc scale dense cores from the entire sample. The mean physical properties for these cores are 1.1 km s-1 in intrinsic linewidth, 18 K in NH3 rotational temperature, 2.3 × 1015 cm-2 in NH3 gas column density, and 67 M ⊙ in molecular mass. The dense cores identified from the filamentary sources are closer to being virialized. Dense cores in the other two categories of sources appear to be dynamically unstable.

  8. Gamma-Ray Observations of the Orion Molecular Clouds with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Allafort, A.; Antolini, E.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Ferrara, E. C.; Harding, A. K.; Troja, E.

    2012-01-01

    We report on the gamma-ray observations of giant molecular clouds Orion A and B with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. The gamma-ray emission in the energy band between approx 100 MeV and approx 100 GeV is predicted to trace the gas mass distribution in the clouds through nuclear interactions between the Galactic cosmic rays (CRs) and interstellar gas. The gamma-ray production cross-section for the nuclear interaction is known to approx 10% precision which makes the LAT a powerful tool to measure the gas mass column density distribution of molecular clouds for a known CR intensity. We present here such distributions for Orion A and B, and correlate them with those of the velocity-integrated CO intensity (W(sub CO)) at a 1 deg 1 deg pixel level. The correlation is found to be linear over a W(sub CO) range of approx 10-fold when divided in three regions, suggesting penetration of nuclear CRs to most of the cloud volumes. The W(sub CO)-to-mass conversion factor, X(sub CO), is found to be approx 2.3 10(exp 20) / sq cm (K km/s)(exp -1) for the high-longitude part of Orion A (l > 212 deg), approx 1.7 times higher than approx 1.3 10(exp 20) found for the rest of Orion A and B. We interpret the apparent high X(sub CO) in the high-longitude region of Orion A in the light of recent works proposing a nonlinear relation between H2 and CO densities in the diffuse molecular gas.W(sub CO) decreases faster than the H2 column density in the region making the gas "darker" to W(sub CO).

  9. Tests on Stiffened Circular Cylinders

    NASA Technical Reports Server (NTRS)

    Holt, Marshall

    1941-01-01

    Compressive tests were made of two series of stiffened circular cylindrical shells under axial load. All the shells were 16 inches in diameter by 24 inches in length and were made of aluminum-alloy sheet curved to the proper radius and welded with one longitudinal weld. The ratios of diameter to thickness of shell wall in the two series of specimens were 258 and 572. Strains were measured with Huggenberger tensometers at a number of gage lines on the stiffeners and shell. The results of these tests indicate that a spacing of circumferential stiffeners equal to 0.67 times the radius is too great to strengthen the shell wall appreciably. The results are not inclusive enough to show the optimum in stiffeners. Plain cylinders without stiffeners developed ultimate strengths approximately half as great as the buckling strengths computed by the equation resulting from the classical theory and slightly greater than those computed by Donnell's large deflection theory.

  10. Orbital Circularization of Hot and Cool Kepler Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Van Eylen, Vincent; Winn, Joshua N.; Albrecht, Simon

    2016-06-01

    The rate of tidal circularization is predicted to be faster for relatively cool stars with convective outer layers, compared to hotter stars with radiative outer layers. Observing this effect is challenging because it requires large and well-characterized samples that include both hot and cool stars. Here we seek evidence of the predicted dependence of circularization upon stellar type, using a sample of 945 eclipsing binaries observed by Kepler. This sample complements earlier studies of this effect, which employed smaller samples of better-characterized stars. For each Kepler binary we measure e cos ω based on the relative timing of the primary and secondary eclipses. We examine the distribution of e cos ω as a function of period for binaries composed of hot stars, cool stars, and mixtures of the two types. At the shortest periods, hot-hot binaries are most likely to be eccentric; for periods shorter than four days, significant eccentricities occur frequently for hot-hot binaries, but not for hot-cool or cool-cool binaries. This is in qualitative agreement with theoretical expectations based on the slower dissipation rates of hot stars. However, the interpretation of our results is complicated by the largely unknown ages and evolutionary states of the stars in our sample.

  11. Wind Turbine Wake Variability in a Large Wind Farm, Observed by Scanning Lidar

    NASA Astrophysics Data System (ADS)

    Lundquist, J. K.; Xiaoxia, G.; Aitken, M.; Quelet, P. T.; Rana, J.; Rhodes, M. E.; St Martin, C. M.; Tay, K.; Worsnop, R.; Irvin, S.; Rajewski, D. A.; Takle, E. S.

    2014-12-01

    Although wind turbine wake modeling is critical for accurate wind resource assessment, operational forecasting, and wind plant optimization, verification of such simulations is currently constrained by sparse datasets taken in limited atmospheric conditions, often of single turbines in isolation. To address this knowledge gap, our team deployed a WINDCUBE 200S scanning lidar in a 300-MW operating wind farm as part of the CWEX-13 field experiment. The lidar was deployed ~2000 m from a row of four turbines, such that wakes from multiple turbines could be sampled with horizontal scans. Twenty minutes of every hour were devoted to horizontal scans at ½ degree resolution at six different elevation angles. Twenty-five days of data were collected, with wind speeds at hub height ranging from quiescent to 14 m/s, and atmospheric stability varying from unstable to strongly stable. The example scan in Fig. 1a shows wakes from a row of four turbines propagating to the northwest. This extensive wake dataset is analyzed based on the quantitative approach of Aitken et al. (J. Atmos. Ocean. Technol. 2014), who developed an automated wake detection algorithm to characterize wind turbine wakes from scanning lidar data. We have extended the Aitken et al. (2014) method to consider multiple turbines in a single scan in order to classify the large numbers of wakes observed in the CWEX-13 dataset (Fig. 1b) during southerly flow conditions. The presentation will explore the variability of wake characteristics such as the velocity deficit and the wake width. These characteristics vary with atmospheric stability, atmospheric turbulence, and inflow wind speed. We find that the strongest and most persistent wakes occur at low to moderate wind speeds (region 2 of the turbine power curve) in stable conditions. We also present evidence that, in stable conditions with strong changes of wind direction with height, wakes propagate in different directions at different elevations above the surface

  12. Large scale IRAM 30 m CO-observations in the giant molecular cloud complex W43

    NASA Astrophysics Data System (ADS)

    Carlhoff, P.; Nguyen Luong, Q.; Schilke, P.; Motte, F.; Schneider, N.; Beuther, H.; Bontemps, S.; Heitsch, F.; Hill, T.; Kramer, C.; Ossenkopf, V.; Schuller, F.; Simon, R.; Wyrowski, F.

    2013-12-01

    We aim to fully describe the distribution and location of dense molecular clouds in the giant molecular cloud complex W43. It was previously identified as one of the most massive star-forming regions in our Galaxy. To trace the moderately dense molecular clouds in the W43 region, we initiated W43-HERO, a large program using the IRAM 30 m telescope, which covers a wide dynamic range of scales from 0.3 to 140 pc. We obtained on-the-fly-maps in 13CO (2-1) and C18O (2-1) with a high spectral resolution of 0.1 km s-1 and a spatial resolution of 12''. These maps cover an area of ~1.5 square degrees and include the two main clouds of W43 and the lower density gas surrounding them. A comparison to Galactic models and previous distance calculations confirms the location of W43 near the tangential point of the Scutum arm at approximately 6 kpc from the Sun. The resulting intensity cubes of the observed region are separated into subcubes, which are centered on single clouds and then analyzed in detail. The optical depth, excitation temperature, and H2 column density maps are derived out of the 13CO and C18O data. These results are then compared to those derived from Herschel dust maps. The mass of a typical cloud is several 104 M⊙ while the total mass in the dense molecular gas (>102 cm-3) in W43 is found to be ~1.9 × 106 M⊙. Probability distribution functions obtained from column density maps derived from molecular line data and Herschel imaging show a log-normal distribution for low column densities and a power-law tail for high densities. A flatter slope for the molecular line data probability distribution function may imply that those selectively show the gravitationally collapsing gas. Appendices are available in electronic form at http://www.aanda.orgThe final datacubes (13CO and C18O) for the entire survey are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/560/A24

  13. VERY LARGE ARRAY OBSERVATIONS OF THE INFRARED DARK CLOUD G19.30+0.07

    SciTech Connect

    Devine, K. E.; Churchwell, E.; Chandler, C. J.; Borg, K. J.; Brogan, C.; Indebetouw, R.; Shirley, Y.

    2011-05-20

    We present Very Large Array observations of ammonia (NH{sub 3}) (1,1), (2,2), and dicarbon sulfide (CCS) (2{sub 1}-1{sub 0}) emission toward the infrared dark cloud (IRDC) G19.30+0.07 at {approx}22 GHz. The NH{sub 3} emission closely follows the 8 {mu}m extinction. The NH{sub 3} (1,1) and (2,2) lines provide diagnostics of the temperature and density structure within the IRDC, with typical rotation temperatures of {approx}10-20 K and NH{sub 3} column densities of {approx}10{sup 15} cm{sup -2}. The estimated total mass of G19.30+0.07 is {approx}1130 M{sub sun}. The cloud comprises four compact NH{sub 3} clumps of mass {approx}30-160 M{sub sun}. Two coincide with 24 {mu}m emission, indicating heating by protostars, and show evidence of outflow in the NH{sub 3} emission. We report a water maser associated with a third clump; the fourth clump is apparently starless. A non-detection of 8.4 GHz emission suggests that the IRDC contains no bright H II regions and places a limit on the spectral type of an embedded zero-age main-sequence star to early-B or later. From the NH{sub 3} emission, we find that G19.30+0.07 is composed of three distinct velocity components or 'subclouds'. One velocity component contains the two 24 {mu}m sources and the starless clump, another contains the clump with the water maser, while the third velocity component is diffuse, with no significant high-density peaks. The spatial distribution of NH{sub 3} and CCS emission from G19.30+0.07 is highly anti-correlated, with the NH{sub 3} predominantly in the high-density clumps and the CCS tracing lower-density envelopes around those clumps. This spatial distribution is consistent with theories of evolution for chemically young low-mass cores, in which CCS has not yet been processed to other species and/or depleted in high-density regions.

  14. Observing Dynamics in Large-Scale Birkeland Currents with the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE)

    NASA Astrophysics Data System (ADS)

    Anderson, B. J.; Korth, H.; Waters, C. L.; Barnes, R. J.; Olson, C.

    2015-12-01

    The Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) provides continuous global observations of the magnetic perturbations that predominantly reflect Birkeland currents. The data are acquired by avionics magnetometers of the Iridium satellites and allow measurements from 66 satellites in near-polar circular, low altitude orbits. The configuration of the Iridium satellite constellation determines the longitude sampling spacing of ~ 2 hours and the re-sampling cadence of the system which is 9 minutes. From 2008 to 2013 the AMPERE system was developed which included new flight software on the Iridium satellites to allow telemetry of higher rate data to the ground and the Science Data Center to derive Birkeland current perturbations from the data and invert these signals to derive the global distributions of the currents using data windows of ten minutes. There were many challenges in developing AMPERE including automating inter-calibration between satellites and the baseline determination and removals. The results of AMPERE provide stunning confirmation of many of the statistical estimates for the distribution of currents but more significantly open a new window to understand their instantaneous distribution and dynamics. Examples of new features of the currents and their dynamics revealed by AMPERE are presented. In addition, prospects for new data products and increased data quality anticipated from AMPERE-NEXT to be implemented on the Iridium-NEXT generation of satellites are discussed.

  15. Circular polarization of radio emission from air showers in thunderstorm conditions

    NASA Astrophysics Data System (ADS)

    Trinh, T. N. G.; Scholten, O.; Bonardi, A.; Buitink, S.; Corstanje, A.; Ebert, U.; Enriquez, J. E.; Falcke, H.; Hörandel, J. R.; Mitra, P.; Mulrey, K.; Nelles, A.; Thoudam, S.; Rachen, J. P.; Rossetto, L.; Rutjes, C.; Schellart, P.; ter Veen, S.; Winchen, T.

    2017-03-01

    We present measured radio emission from cosmic-ray-induced air showers under thunderstorm conditions. We observe for these events large differences in intensity, linear polarization and circular polarization from the events measured under fair-weather conditions. This can be explained by the effects of atmospheric electric fields in thunderclouds. Therefore, measuring the intensity and polarization of radio emission from cosmic ray extensive air showers during thunderstorm conditions provides a new tool to probe the atmospheric electric fields present in thunderclouds.

  16. Integrated observations of processes and products of large scale cratering experiments

    NASA Astrophysics Data System (ADS)

    Graettinger, A. H.; Sonder, I.; Valentine, G.; Ross, P.; White, J. D.; Taddeucci, J.; Zimanowski, B.; Lube, G.; Kueppers, U.; Bowman, D. C.

    2013-12-01

    Detailed analysis of volcanic craters and ballistic deposits can provide insight into eruption dynamics and evolution. As fully exposed craters and associated unmodified deposits are rarely preserved, the dynamics involved can only be inferred. Large-scale blast experiments conducted at the University at Buffalo Geohazards Field Station produced deposits from single and multiple subsurface explosions at individual craters, along with a range of observational data, and provide a unique opportunity to link dynamics with geologic structures and deposits. Meter-scale craters were produced through repeated blasts using chemical explosives in 15 cm thick strata constructed of compacted aggregates (e.g. sands and gravels). Each experiment had 1-3 individual explosions with the same epicenter to form a single crater, with a total of 12 blasts and five craters. Three craters were produced through a series of shallow blasts (34-75 cm depth, six blasts) and two additional craters were produced by deeper blasts (75-100 cm, six blasts). The experiments successfully reproduced crater structures similar to those of maar volcanoes, which are the product of one or more subsurface explosions resulting from the interaction of magma with groundwater. Deep explosion tests successfully reproduced mixing and structures similar to maar-diatremes. The ballistics produced were collected in sample boxes up to 18 m from the blast center. The pits were later excavated and the vertical structures and deposits were described and sampled. Deposits can be described as bedded-diatreme (fallback/inter-crater deposits), unbedded diatreme (disturbed subsurface material), tephra ring (debris on the pre-blast surface) and distal extra-crater deposits. Granulometry and componentry were acquired for all samples. The diatreme structures and deposit componentry were interpreted using high-speed video recordings of the blasts. A comparison of ballistic source depth and collection location revealed the

  17. Can simple population genetic models reconcile partial match frequencies observed in large forensic databases?

    PubMed

    Mueller, Laurence D

    2008-08-01

    A recent study of partial matches in the Arizona offender database of DNA profiles has revealed a large number of nine and ten locus matches. I use simple models that incorporate the product rule, population substructure, and relatedness to predict the expected number of matches in large databases. I find that there is a relatively narrow window of parameter values that can plausibly describe the Arizona results. Further research could help determine if the Arizona samples are congruent with some of the models presented here or whether fundamental assumptions for predicting these match frequencies requires adjustments.

  18. Fermi Large Area Telescope Observations of the Dark Accelerator HESS J1745-303

    NASA Astrophysics Data System (ADS)

    Yeung, Paul

    2016-12-01

    Reviewing the two MeV-GeV investigations in the field of the HESS J1745-303 performed using Fermi Large Area Telescope data, we confirmed that the emission peak comfortably coincides with ‘Region A’ in the TeV regime, which is the brightest part of this feature. The MeV–TeV spectrum can be precisely described by a single power-law. Also, recent investigation has shown that the MeV-GeV feature is elongated from ‘Region A’ toward the north-west, which is similar to the case of large- scale atomic/molecular gas distribution.

  19. Circular dichroism in biological photonic crystals and cubic chiral nets.

    PubMed

    Saba, M; Thiel, M; Turner, M D; Hyde, S T; Gu, M; Grosse-Brauckmann, K; Neshev, D N; Mecke, K; Schröder-Turk, G E

    2011-03-11

    Nature provides impressive examples of chiral photonic crystals, with the notable example of the cubic so-called srs network (the label for the chiral degree-three network modeled on SrSi2) or gyroid structure realized in wing scales of several butterfly species. By a circular polarization analysis of the band structure of such networks, we demonstrate strong circular dichroism effects: The butterfly srs microstructure, of cubic I4(1)32 symmetry, shows significant circular dichroism for blue to ultraviolet light, that warrants a search for biological receptors sensitive to circular polarization. A derived synthetic structure based on four like-handed silicon srs nets exhibits a large circular polarization stop band of a width exceeding 30%. These findings offer design principles for chiral photonic devices.

  20. Cytological Observations of the Large Symbiotic Foraminifer Amphisorus kudakajimensis Using Calcein Acetoxymethyl Ester

    PubMed Central

    Ohno, Yoshikazu; Fujita, Kazuhiko; Toyofuku, Takashi; Nakamaura, Takashi

    2016-01-01

    Large benthic foraminifera are unicellular calcifying reef organisms that can form symbiotic relationships with a range of different microalgae. However, the cellular functions, such as symbiosis and calcification, and other aspects of cellular physiology in large benthic foraminifera are not fully understood. Amphisorus kudakajimensis was used as a model to determine the detailed cellular characteristics of large benthic foraminifera. We used calcein acetoxymethyl ester (calcein AM) as a fluorescent indicator for live confocal imaging. We demonstrated that calcein AM is a useful fluorescent indicator to stain the fine network of reticulopodia and the cytoplasm in living A. kudakajimensis. We showed that at least two types of reticulopodia exist in A. kudakajimensis: the straight bundle of reticulopodia that spreads from the aperture and the fine reticulopodia along the surface of the aperture and chamber walls. The cytoplasm in outer chambers was highly branched and contained a few dinoflagellates. In contrast, the inner chamberlets contained condensed cytoplasm and many dinoflagellates, suggesting that the cytoplasm of A. kudakajimensis performs different functions based on its location within the large test. Our confocal detailed image analysis provides real-time cellular morphology and cell physiology of living foraminifera. PMID:27812157

  1. The beginning of observations of large-scale solar magnetic fields at the Sayan Observatory - Instrument, plans, preliminary results

    NASA Astrophysics Data System (ADS)

    Grigoryev, V. M.; Peshcherov, V. S.; Demidov, M. L.

    A telescope and a system for measuring large-scale magnetic fields and the large-scale field of line-of-sight velocities in the sun photosphere have been constructed at the Sayan Observatory (USSR). The instrument permits the following synoptic observations of large-scale structures: (1) magnetograms of a large-scale magnetic field with a 3-arcmin resolution and 0.1-0.2 Gs sensitivity; (2) solar disk magnetograms in the form of half-tone images of the magnetic field distribution with 15 Gs sensitivity and 8 x 8 arcsec resolution; and (3) measurement of the mean magnetic field of the sun as a star with about 0.1 Gs sensitivity. Preliminary results of toroidal magnetic field observations are briefly discussed.

  2. CIRCULAR CAVITY SLOT ANTENNA

    DOEpatents

    Kerley, P.L.

    1959-01-01

    A small-size antenna having a doughnut-shaped field pattern and which can act both as an antenna and a resonant circuit is described. The antenna is of the slotted type and comprises a resonant cavity with a center hole. A circular slot is provided in one wall of the cavity concentric with the hole and a radio frequency source is connected across the slot. The pattern and loading of the antenna are adjusted by varying the position and shape of a center element slidably disposed within the hole and projecting from the slotted side of the resonant cavity. The disclosed structure may also be used to propagate the oscillator signal down a transniission line by replacing the center element with one leg of the transmission line in a spaced relation from the walls of the cavity.

  3. Circularly Polarized MHOHG with Bichromatic Circularly Polarized Laser Pulses

    NASA Astrophysics Data System (ADS)

    Bandrauk, Andre D.; Mauger, Francois; Uzer, Turgay

    2016-05-01

    Circularly polarized MHOHG-Molecular High Order Harmonic Generation is shown to occur efficiently with intense ultrashort bichromatic circularly polarized pulses due to frequent electron-parent -ion recollision with co-or counter-rotating incident circular pulses as predicted in 1995. We show in this context that molecules offer a very robust and efficient frameworkfor the production of circularly polarized harmonics for the generation of single circularly polarized ``attosecond'' pulses. The efficiency of such new MHOHG is shown to depend on the compatibility of the symmetry of the molecular medium with the net electric field generated by the combination of the laser pulses.Using a time-dependent symmetry analysis with concrete examples such as H 2 + vs H 3 + we show how all the features(harmonic order and ∧ polarization) of MHOHG can be explained and predicted.

  4. How historic simulation-observation discrepancy affects future warming projections in a very large model ensemble

    NASA Astrophysics Data System (ADS)

    Goodwin, Philip

    2016-10-01

    Projections of future climate made by model-ensembles have credibility because the historic simulations by these models are consistent with, or near-consistent with, historic observations. However, it is not known how small inconsistencies between the ranges of observed and simulated historic climate change affects the future projections made by a model ensemble. Here, the impact of historical simulation-observation inconsistencies on future warming projections is quantified in a 4-million member Monte Carlo ensemble from a new efficient Earth System Model (ESM). Of the 4-million ensemble members, a subset of 182,500 are consistent with historic ranges of warming, heat uptake and carbon uptake simulated by the Climate Model Intercomparison Project 5 (CMIP5) ensemble. This simulation-consistent subset projects similar future warming ranges to the CMIP5 ensemble for all four RCP scenarios, indicating the new ESM represents an efficient tool to explore parameter space for future warming projections based on historic performance. A second subset of 14,500 ensemble members are consistent with historic observations for warming, heat uptake and carbon uptake. This observation-consistent subset projects a narrower range for future warming, with the lower bounds of projected warming still similar to CMIP5, but the upper warming bounds reduced by 20-35 %. These findings suggest that part of the upper range of twenty-first century CMIP5 warming projections may reflect historical simulation-observation inconsistencies. However, the agreement of lower bounds for projected warming implies that the likelihood of warming exceeding dangerous levels over the twenty-first century is unaffected by small discrepancies between CMIP5 models and observations.

  5. Assessment of a regulatory model performance relative to large spatial inhomogeneity in observed ozone in Houston, TX

    NASA Astrophysics Data System (ADS)

    Couzo, E.; Olatosi, A. O.; Jeffries, H. E.; Vizuete, W.

    2011-12-01

    In Houston, some of the highest measured 8-hr ozone (O3) peaks are characterized by sudden increases in observed concentrations of at least 40 ppb in one hour, or 60 ppb in two hours. Measurements show that these large hourly changes appear at only a few monitors and span a narrow geographic area suggesting a spatially heterogeneous field of O3 concentrations. This study assessed whether a regulatory air quality model (AQM) can simulate this observed behavior. The AQM did not reproduce the magnitude or location of some of the highest observed hourly O3 changes, and it also failed to capture the limited spatial extent. On days with measured large hourly changes in O3 concentrations, the AQM predicted high O3 over large regions of Houston resulting in over predictions at several monitors. This analysis shows that the model can make high O3, but on these days the predicted spatial field suggests that the model had a different cause. Some observed large hourly changes in O3 concentrations have been linked to random releases of industrial volatile organic compounds (VOCs). In the AQM emission inventory there are several emission events when an industrial point source increases VOC emissions in excess of 10,000 mol/hr. One instance increased predicted downwind O3 concentrations up to 25 ppb. These results show that the modeling system is responsive to a large VOC release, but the timing and location of the release, and metrological conditions, are critical requirements. Attainment of the O3 standard requires the use of observational data and AQM predictions. If the large observed hourly changes are indicative of a separate cause of high O3, then the model may not include that cause, which might result in regulators enacting control strategies that could be ineffective.

  6. Assessment of a regulatory model's performance relative to large spatial heterogeneity in observed ozone in Houston, Texas.

    PubMed

    Couzo, Evan; Olatosi, Adeola; Jeffries, Harvey E; Vizuete, William

    2012-06-01

    In Houston, some of the highest measured 8-hr ozone (O3) peaks are characterized by sudden increases in observed concentrations of at least 40 ppb in 1 hr or 60 ppb in 2 hr. Measurements show that these large hourly changes appear at only a few monitors and span a narrow geographic area, suggesting a spatially heterogeneous field of O3 concentrations. This study assessed whether a regulatory air quality model (AQM) can simulate this observed behavior. The AQM did not reproduce the magnitude or location of some of the highest observed hourly O3 changes, and it also failed to capture the limited spatial extent. On days with measured large hourly changes in O3 concentrations, the AQM predicted high O3 over large regions of Houston, resulting in overpredictions at several monitors. This analysis shows that the model can make high O3, but on these days the predicted spatial field suggests that the model had a different cause. Some observed large hourly changes in O3 concentrations have been linked to random releases of industrial volatile organic compounds (VOCs). In the AQM emission inventory, there are several emission events when an industrial point source increases VOC emissions in excess of 10,000 mol/hr. One instance increased predicted downwind O3 concentrations up to 25 ppb. These results show that the modeling system is responsive to a large VOC release, but the timing and location of the release, and meteorological conditions, are critical requirements. Attainment of the O3 standard requires the use of observational data and AQM predictions. If the large observed hourly changes are indicative of a separate cause of high O3, then the model may not include that cause, which might result in regulators enacting control strategies that could be ineffective.

  7. Circularization pathway of a bacterial group II intron

    PubMed Central

    Monat, Caroline; Cousineau, Benoit

    2016-01-01

    Group II introns are large RNA enzymes that can excise as lariats, circles or in a linear form through branching, circularization or hydrolysis, respectively. Branching is by far the main and most studied splicing pathway while circularization was mostly overlooked. We previously showed that removal of the branch point A residue from Ll.LtrB, the group II intron from Lactococcus lactis, exclusively leads to circularization. However, the majority of the released intron circles harbored an additional C residue of unknown origin at the splice junction. Here, we exploited the Ll.LtrB-ΔA mutant to study the circularization pathway of bacterial group II introns in vivo. We demonstrated that the non-encoded C residue, present at the intron circle splice junction, corresponds to the first nt of exon 2. Intron circularization intermediates, harboring the first 2 or 3 nts of exon 2, were found to accumulate showing that branch point removal leads to 3′ splice site misrecognition. Traces of properly ligated exons were also detected functionally confirming that a small proportion of Ll.LtrB-ΔA circularizes accurately. Overall, our data provide the first detailed molecular analysis of the group II intron circularization pathway and suggests that circularization is a conserved splicing pathway in bacteria. PMID:26673697

  8. Large Amplitude Whistler Waves and Electron Acceleration in the Earth's Radiation Belts: A Review of STEREO and Wind Observations

    NASA Technical Reports Server (NTRS)

    Cattell, Cynthia; Breneman, A.; Goetz, K.; Kellogg, P.; Kersten, K.; Wygant, J.; Wilson, L. B., III; Looper, Mark D.; Blake, J. Bernard; Roth, I.

    2012-01-01

    One of the critical problems for understanding the dynamics of Earth's radiation belts is determining the physical processes that energize and scatter relativistic electrons. We review measurements from the Wind/Waves and STEREO S/Waves waveform capture instruments of large amplitude whistler-mode waves. These observations have provided strong evidence that large amplitude (100s mV/m) whistler-mode waves are common during magnetically active periods. The large amplitude whistlers have characteristics that are different from typical chorus. They are usually nondispersive and obliquely propagating, with a large longitudinal electric field and significant parallel electric field. We will also review comparisons of STEREO and Wind wave observations with SAMPEX observations of electron microbursts. Simulations show that the waves can result in energization by many MeV and/or scattering by large angles during a single wave packet encounter due to coherent, nonlinear processes including trapping. The experimental observations combined with simulations suggest that quasilinear theoretical models of electron energization and scattering via small-amplitude waves, with timescales of hours to days, may be inadequate for understanding radiation belt dynamics.

  9. Testing of Large Diameter Fresnel Optics for Space Based Observations of Extensive Air Showers

    NASA Technical Reports Server (NTRS)

    Adams, James H.; Christl, Mark J.; Young, Roy M.

    2011-01-01

    The JEM-EUSO mission will detect extensive air showers produced by extreme energy cosmic rays. It operates from the ISS looking down on Earth's night time atmosphere to detect the nitrogen fluorescence and Cherenkov produce by the charged particles in the EAS. The JEM-EUSO science objectives require a large field of view, sensitivity to energies below 50 EeV, and must fit within available ISS resources. The JEM-EUSO optic module uses three large diameter, thin plastic lenses with Fresnel surfaces to meet the instrument requirements. A bread-board model of the optic has been manufactured and has undergone preliminary tests. We report the results of optical performance tests and evaluate the present capability to manufacture these optical elements.

  10. Retrograde diurnal motion of the instantaneous rotation axis observed by a large ring laser gyroscope

    NASA Astrophysics Data System (ADS)

    Tian, W.

    2017-01-01

    Ring laser gyroscope technique directly senses the Earth's instantaneous rotation pole (IRP), whose polar motion contains strong retrograde diurnal components induced by external torques due to the gravitational attraction of the Moon and Sun. The first direct measurement of this retrograde diurnal motion with three large ring lasers was reported by Schreiber et al. (J Geophys Res 109(B18):B06405, significant increase in precision and stability of ring laser gyroscopes; however, precise determination of amplitude and phase at main partial waves has not been given in the literature. In this paper, I will report on determination of the retrograde diurnal motion of the IRP at main partial waves (Oo_1, J_1, K_1, M_1, O_1, Q_1) by the ring laser "G", located in Wettzell, Germany, which is the most stable one amongst the currently running large ring laser gyroscopes.

  11. Search for Electromagnetic Counterparts to LIGO-Virgo Candidates: Expanded Very Large Array Observations

    NASA Technical Reports Server (NTRS)

    Lazio, Joseph; Keating, Katie; Jenet, F. A.; Kassim, N. E.

    2011-01-01

    This paper summarizes a search for radio wavelength counterparts to candidate gravitational wave events. The identification of an electromagnetic counterpart could provide a more complete understanding of a gravitational wave event, including such characteristics as the location and the nature of the progenitor. We used the Expanded Very Large Array (EVLA) to search six galaxies which were identified as potential hosts for two candidate gravitational wave events. We summarize our procedures and discuss preliminary results.

  12. Observation and analysis of high-speed human motion with frequent occlusion in a large area

    NASA Astrophysics Data System (ADS)

    Wang, Yuru; Liu, Jiafeng; Liu, Guojun; Tang, Xianglong; Liu, Peng

    2009-12-01

    The use of computer vision technology in collecting and analyzing statistics during sports matches or training sessions is expected to provide valuable information for tactics improvement. However, the measurements published in the literature so far are either unreliably documented to be used in training planning due to their limitations or unsuitable for studying high-speed motion in large area with frequent occlusions. A sports annotation system is introduced in this paper for tracking high-speed non-rigid human motion over a large playing area with the aid of motion camera, taking short track speed skating competitions as an example. The proposed system is composed of two sub-systems: precise camera motion compensation and accurate motion acquisition. In the video registration step, a distinctive invariant point feature detector (probability density grads detector) and a global parallax based matching points filter are used, to provide reliable and robust matching across a large range of affine distortion and illumination change. In the motion acquisition step, a two regions' relationship constrained joint color model and Markov chain Monte Carlo based joint particle filter are emphasized, by dividing the human body into two relative key regions. Several field tests are performed to assess measurement errors, including comparison to popular algorithms. With the help of the system presented, the system obtains position data on a 30 m × 60 m large rink with root-mean-square error better than 0.3975 m, velocity and acceleration data with absolute error better than 1.2579 m s-1 and 0.1494 m s-2, respectively.

  13. Constraining Large-Scale Solar Magnetic Field Models with Optical Coronal Observations

    NASA Astrophysics Data System (ADS)

    Uritsky, V. M.; Davila, J. M.; Jones, S. I.

    2015-12-01

    Scientific success of the Solar Probe Plus (SPP) and Solar Orbiter (SO) missions will depend to a large extent on the accuracy of the available coronal magnetic field models describing the connectivity of plasma disturbances in the inner heliosphere with their source regions. We argue that ground based and satellite coronagraph images can provide robust geometric constraints for the next generation of improved coronal magnetic field extrapolation models. In contrast to the previously proposed loop segmentation codes designed for detecting compact closed-field structures above solar active regions, we focus on the large-scale geometry of the open-field coronal regions located at significant radial distances from the solar surface. Details on the new feature detection algorithms will be presented. By applying the developed image processing methodology to high-resolution Mauna Loa Solar Observatory images, we perform an optimized 3D B-line tracing for a full Carrington rotation using the magnetic field extrapolation code presented in a companion talk by S.Jones at al. Tracing results are shown to be in a good qualitative agreement with the large-scalie configuration of the optical corona. Subsequent phases of the project and the related data products for SSP and SO missions as wwll as the supporting global heliospheric simulations will be discussed.

  14. Observations and implications of large-amplitude longitudinal oscillations in a solar filament

    SciTech Connect

    Luna, M.; Knizhnik, K.; Muglach, K.; Karpen, J.; Gilbert, H.; Kucera, T. A.; Uritsky, V.

    2014-04-10

    On 2010 August 20, an energetic disturbance triggered large-amplitude longitudinal oscillations in a nearby filament. The triggering mechanism appears to be episodic jets connecting the energetic event with the filament threads. In the present work, we analyze this periodic motion in a large fraction of the filament to characterize the underlying physics of the oscillation as well as the filament properties. The results support our previous theoretical conclusions that the restoring force of large-amplitude longitudinal oscillations is solar gravity, and the damping mechanism is the ongoing accumulation of mass onto the oscillating threads. Based on our previous work, we used the fitted parameters to determine the magnitude and radius of curvature of the dipped magnetic field along the filament, as well as the mass accretion rate onto the filament threads. These derived properties are nearly uniform along the filament, indicating a remarkable degree of cohesiveness throughout the filament channel. Moreover, the estimated mass accretion rate implies that the footpoint heating responsible for the thread formation, according to the thermal nonequilibrium model, agrees with previous coronal heating estimates. We estimate the magnitude of the energy released in the nearby event by studying the dynamic response of the filament threads, and discuss the implications of our study for filament structure and heating.

  15. Special configuration of a very large Schmidt telescope for extensive astronomical spectroscopic observation.

    PubMed

    Wang, S G; Su, D Q; Chu, Y Q; Cui, X; Wang, Y N

    1996-09-01

    A special reflecting Schmidt telescope is used to observe celestial objects. The telescope has an aperture of 4m, f ratio of 5, and a 5° field of view. Its optical axis is fixed and tilted 25° to the horizontal that runs from south to north. The celestial objects were observed for 1.5 h as they passed through the meridian. The shape of the reflecting Schmidt plate has to be changed with each different declination δ and in the tracking process. This is achieved with active optics. The sky area to be observed is -10° ≤ δ ≤ +90°. There are plans to place ~4000 optical fibers on the telescope focal surface that will lead to a dozen spectrographs.

  16. Twelve thousand laser-AO observations: first results from the Robo-AO large surveys

    NASA Astrophysics Data System (ADS)

    Law, Nicholas M.; Baranec, Christoph; Riddle, Reed L.

    2014-07-01

    Robo-AO is the first AO system which can feasibly perform surveys of thousands of targets. The system has been operating in a fully robotic mode on the Palomar 1.5m telescope for almost two years. Robo-AO has completed nearly 12,000 high-angular-resolution observations in almost 20 separate science programs including exoplanet characterization, field star binarity, young star binarity and solar system observations. We summarize the Robo-AO surveys and the observations completed to date. We also describe the data-reduction pipeline we developed for Robo-AO—the first fully-automated AO data-reduction, point-spread-function subtraction and companion-search pipeline.

  17. MIC-Large Scale Magnetically Inflated Cable Structures for Space Power, Propulsion, Communications and Observational Applications

    NASA Astrophysics Data System (ADS)

    Powell, James; Maise, George; Rather, John

    2010-01-01

    A new approach for the erection of rigid large scale structures in space-MIC (Magnetically Inflated Cable)-is described. MIC structures are launched as a compact payload of superconducting cables and attached tethers. After reaching orbit, the superconducting cables are energized with electrical current. The magnet force interactions between the cables cause them to expand outwards into the final large structure. Various structural shapes and applications are described. The MIC structure can be a simple flat disc with a superconducting outer ring that supports a tether network holding a solar cell array, or it can form a curved mirror surface that concentrates light and focuses it on a smaller region-for example, a high flux solar array that generates electric power, a high temperature receiver that heats H2 propellant for high Isp propulsion, and a giant primary reflector for a telescope for astronomy and Earth surveillance. Linear dipole and quadrupole MIC structures are also possible. The linear quadrupole structure can be used for magnetic shielding against cosmic radiation for astronauts, for example. MIC could use lightweight YBCO superconducting HTS (High Temperature Superconductor) cables, that can operate with liquid N2 coolant at engineering current densities of ~105 amp/cm2. A 1 kilometer length of MIC cable would weigh only 3 metric tons, including superconductor, thermal insulations, coolant circuits, and refrigerator, and fit within a 3 cubic meter compact package for launch. Four potential MIC applications are described: Solar-thermal propulsion using H2 propellant, space based solar power generation for beaming power to Earth, a large space telescope, and solar electric generation for a manned lunar base. The first 3 applications use large MIC solar concentrating mirrors, while the 4th application uses a surface based array of solar cells on a magnetically levitated MIC structure to follow the sun. MIC space based mirrors can be very large and light

  18. Vortex shedding noise control in idling circular saws using air ejection at the teeth

    NASA Astrophysics Data System (ADS)

    Yanagimoto, K.; Mote, C. D.; Ichimiya, R.

    1994-04-01

    Aerodynamically induced noise from an idling circular saw can be very intense. The purpose of the present investigation is noise reduction through vortex shedding control in idling circular saws. Reduction of aerodynamic noise in idling circular saws may be possible by controlling the shed vortices and flow structures in the space between teeth, based on the earlier observations.

  19. The large-scale observational signatures of low-mass galaxies during reionization

    NASA Astrophysics Data System (ADS)

    Dixon, Keri L.; Iliev, Ilian T.; Mellema, Garrelt; Ahn, Kyungjin; Shapiro, Paul R.

    2016-03-01

    Observations of the epoch of reionization give us clues about the nature and evolution of the sources of ionizing photons, or early stars and galaxies. We present a new suite of structure formation and radiative transfer (RT) simulations from the PRACE4LOFAR project designed to investigate whether the mechanism of radiative feedback, or the suppression of star formation in ionized regions from UV radiation, can be inferred from these observations. Our source halo mass extends down to 108 M⊙, with sources in the mass range 108-109 M⊙ expected to be particularly susceptible to feedback from ionizing radiation, and we vary the aggressiveness and nature of this suppression. Not only do we have four distinct source models, we also include two box sizes (67 and 349 Mpc), each with two grid resolutions. This suite of simulations allows us to investigate the robustness of our results. All of our simulations are broadly consistent with the observed electron-scattering optical depth of the cosmic microwave background and the neutral fraction and photoionization rate of hydrogen at z ˜ 6. In particular, we investigate the redshifted 21-cm emission in anticipation of upcoming radio interferometer observations. We find that the overall shape of the 21-cm signal and various statistics are robust to the exact nature of source suppression, the box size, and the resolution. There are some promising model discriminators in the non-Gaussianity and small-scale power spectrum of the 21-cm signal.

  20. A large Italian observational multicentre study on vascular ulcers of the lower limbs (Studio Ulcere Vascolari).

    PubMed

    Apollonio, Alessandro; Antignani, Pier L; Di Salvo, Michelangelo; Failla, Giacomo; Guarnera, Giorgio; Mosti, Giovanni; Ricci, Elia

    2016-02-01

    An observational study of 2 years was promoted by the Italian Association for Cutaneous Ulcers (AIUC) in order to monitor the epidemiology of leg ulcers, the trend of healing and the more frequent therapeutic approaches in lower limb ulcers. Fifty-nine sites in 14 different Italian regions involved in the study, with 1333 enrolled patients (1163 patients fully evaluated and followed up for 9 months). A prevalence of females (62%) was observed with a mean age of 70 years and a high rate of hypertension (62%), diabetes (38%) and obesity (29%). Venous ulcer was most frequent (55%), followed by mixed (25%) and diabetic (8·3%) ulcers. Basically, all patients received a local therapy (LT) (compression and advanced local therapies), while 63% of patients have an associated systemic pharmaceutical treatment. Ulcer healing rates progressively increased throughout the study and despite the type of observational study does not allow conclusions on the treatment, it was observed that the patients receiving additional systemic drugs were associated with a more rapid acceleration of healing rates of ulcers compared to LT alone (3 months: 39·7% versus 29·2%; 6 months: 62·0% versus 47·0%; 9 months: 74·7% versus 63·8%). In particular, the Studio Ulcere Vascolari (SUV) study showed that a combination treatment with sulodexide and compression therapy allows for a greater increase in the healing rates in venous ulcers.

  1. Placement of the dam for the no. 2 kambaratinskaya HPP by large-scale blasting: some observations

    SciTech Connect

    Shuifer, M. I.; Argal, E. S.

    2011-11-15

    Results of complex instrument observations of large-scale blasting during construction of the dam for the No. 2 Kambaratinskaya HPP on the Naryn River in the Republic of Kirgizia are analyzed. The purpose of these observations was: to determine the actual parameters of the seismic process, evaluate the effect of air and acoustic shock waves, and investigate the kinematics of the surface formed by the blast in its core region within the mass of fractured rocks.

  2. Estimating the impact of satellite observations on large-scale river flood forecasting

    NASA Astrophysics Data System (ADS)

    Andreadis, Konstantinos; Schumann, Guy

    2014-05-01

    Floods are one of the costliest natural disasters, posing severe risks to human population. Hydraulic models are able to predict flood characteristics, such as water surface elevations and inundated area, and are being used for forecasting operationally although there are many uncertainties. In this work, the potential value of satellite observations to initialize these hydraulic models (and their forecasts correspondingly) is explored. The Ensemble Sensitivity method is adapted to evaluate the impact of potential satellite observations on the forecasting of flood characteristics. The estimation of the impact is based on the Local Ensemble Transform Kalman Filter, allowing for the forecast error reductions to be computed without additional model runs. The study area was located in the Ohio River basin, and the model used was the LISFLOOD-FP hydrodynamic model. The experimental design consisted of two configurations of the LISFLOOD-FP model. The first (baseline) simulation represents a calibrated 'best effort' model based on a sub-grid channel structure using observations for parameters and boundary conditions, whereas the second (background) simulation consists of estimated parameters and SRTM-based boundary conditions. Results showed that the forecast skill was improved for water heights up to lead times of 11 days, while even partial observations of the river contained information for the entire river's water surface profile and allowed forecasting 5 to 7 days ahead. On the other hand, discharge forecasts were not improved as much when assimilating water height observations although forecast errors were reduced. Finally, the potential for identifying errors in the model structure and parameterizations via the ensemble sensitivity method is discussed.

  3. Discovery of Circularly Polarized Radio Emission from SS 433.

    PubMed

    Fender; Rayner; Norris; Sault; Pooley

    2000-02-10

    We report the discovery of circularly polarized radio emission from the radio-jet X-ray binary SS 433 with the Australia Telescope Compact Array. The flux density spectrum of the circular polarization, clearly detected at four frequencies between 1 and 9 GHz, is of the form V~nu-0.9+/-0.1. Multiple components in the source and a lack of very high spatial resolution do not allow a unique determination of the origin of the circular polarization or of the spectrum of fractional polarization. However, we argue that the emission is likely to arise in the inner regions of the binary, possibly via propagation-induced conversion of linear to circular polarization, and the fractional circular polarization of these regions may be as high as 10%. Observations such as these have the potential to help us investigate the composition, whether pairs or baryonic, of the ejecta from X-ray binaries.

  4. Tilt Angle and Footpoint Separation of Small and Large Bipolar Sunspot Regions Observed with HMI

    NASA Astrophysics Data System (ADS)

    McClintock, B. H.; Norton, A. A.

    2016-02-01

    We investigate bipolar sunspot regions and how tilt angle and footpoint separation vary during emergence and decay. The Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory collects data at a higher cadence than historical records and allows for a detailed analysis of regions over their lifetimes. We sample the umbral tilt angle, footpoint separation, and umbral area of 235 bipolar sunspot regions in Helioseismic and Magnetic Imager—Debrecen Data with an hourly cadence. We use the time when the umbral area peaks as time zero to distinguish between the emergence and decay periods of each region and we limit our analysis of tilt and separation behavior over time to within ±96 hr of time zero. Tilt angle evolution is distinctly different for regions with small (≈30 MSH), midsize (≈50 MSH), and large (≈110 MSH) maximum umbral areas, with 45 and 90 MSH being useful divisions for separating the groups. At the peak umbral area, we determine median tilt angles for small (7.°6), midsize (5.°9), and large (9.°3) regions. Within ±48 hr of the time of peak umbral area, large regions steadily increase in tilt angle, midsize regions are nearly constant, and small regions show evidence of negative tilt during emergence. A period of growth in footpoint separation occurs over a 72-hr period for all of the regions from roughly 40 to 70 Mm. The smallest bipoles (<9 MSH) are outliers in that they do not obey Joy's law and have a much smaller footpoint separation. We confirm the Muñoz-Jaramillo et al. (2015) results that the sunspots appear to be two distinct populations.

  5. Limits on large extra dimensions based on observations of neutron stars with the Fermi-LAT

    SciTech Connect

    Ajello, M.; Bechtol, K.; Berenji, B.; Bloom, E.D.; Borgland, A.W.; Buehler, R.; Cameron, R.A.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Barbiellini, G.; Bastieri, D.; Buson, S.; Bonamente, E.; Cecchi, C.; Brigida, M.; Bruel, P.; Caraveo, P.A.; Casandjian, J.M. E-mail: elliott@slac.stanford.edu [Laboratoire AIM, CEA-IRFU Collaboration: Fermi-LAT collaboration; and others

    2012-02-01

    We present limits for the compactification scale in the theory of Large Extra Dimensions (LED) proposed by Arkani-Hamed, Dimopoulos, and Dvali. We use 11 months of data from the Fermi Large Area Telescope (Fermi-LAT) to set gamma ray flux limits for 6 gamma-ray faint neutron stars (NS). To set limits on LED we use the model of Hannestad and Raffelt (HR) that calculates the Kaluza-Klein (KK) graviton production in supernova cores and the large fraction subsequently gravitationally bound around the resulting NS. The predicted decay of the bound KK gravitons to γγ should contribute to the flux from NSs. Considering 2 to 7 extra dimensions of the same size in the context of the HR model, we use Monte Carlo techniques to calculate the expected differential flux of gamma-rays arising from these KK gravitons, including the effects of the age of the NS, graviton orbit, and absorption of gamma-rays in the magnetosphere of the NS. We compare our Monte Carlo-based differential flux to the experimental differential flux using maximum likelihood techniques to obtain our limits on LED. Our limits are more restrictive than past EGRET-based optimistic limits that do not include these important corrections. Additionally, our limits are more stringent than LHC based limits for 3 or fewer LED, and comparable for 4 LED. We conclude that if the effective Planck scale is around a TeV, then for 2 or 3 LED the compactification topology must be more complicated than a torus.

  6. TILT ANGLE AND FOOTPOINT SEPARATION OF SMALL AND LARGE BIPOLAR SUNSPOT REGIONS OBSERVED WITH HMI

    SciTech Connect

    McClintock, B. H.; Norton, A. A. E-mail: aanorton@stanford.edu

    2016-02-10

    We investigate bipolar sunspot regions and how tilt angle and footpoint separation vary during emergence and decay. The Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory collects data at a higher cadence than historical records and allows for a detailed analysis of regions over their lifetimes. We sample the umbral tilt angle, footpoint separation, and umbral area of 235 bipolar sunspot regions in Helioseismic and Magnetic Imager—Debrecen Data with an hourly cadence. We use the time when the umbral area peaks as time zero to distinguish between the emergence and decay periods of each region and we limit our analysis of tilt and separation behavior over time to within ±96 hr of time zero. Tilt angle evolution is distinctly different for regions with small (≈30 MSH), midsize (≈50 MSH), and large (≈110 MSH) maximum umbral areas, with 45 and 90 MSH being useful divisions for separating the groups. At the peak umbral area, we determine median tilt angles for small (7.°6), midsize (5.°9), and large (9.°3) regions. Within ±48 hr of the time of peak umbral area, large regions steadily increase in tilt angle, midsize regions are nearly constant, and small regions show evidence of negative tilt during emergence. A period of growth in footpoint separation occurs over a 72-hr period for all of the regions from roughly 40 to 70 Mm. The smallest bipoles (<9 MSH) are outliers in that they do not obey Joy's law and have a much smaller footpoint separation. We confirm the Muñoz-Jaramillo et al. results that the sunspots appear to be two distinct populations.

  7. Limits on Large Extra Dimensions Based on Observations of Neutron Stars with the Fermi-LAT

    SciTech Connect

    Ajello, M.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, E.D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G.A.; Cameron, R.A.; Caraveo, P.A.; Casandjian, J.M.; Cecchi, C.; Charles, E.; /more authors..

    2012-08-17

    We present limits for the compactification scale in the theory of Large Extra Dimensions (LED) proposed by Arkani-Hamed, Dimopoulos, and Dvali. We use 11 months of data from the Fermi Large Area Telescope (Fermi-LAT) to set gamma ray flux limits for 6 gamma-ray faint neutron stars (NS). To set limits on LED we use the model of Hannestad and Raffelt (HR) that calculates the Kaluza-Klein (KK) graviton production in supernova cores and the large fraction subsequently gravitationally bound around the resulting NS. The predicted decay of the bound KK gravitons to {gamma}{gamma} should contribute to the flux from NSs. Considering 2 to 7 extra dimensions of the same size in the context of the HR model, we use Monte Carlo techniques to calculate the expected differential flux of gamma-rays arising from these KK gravitons, including the effects of the age of the NS, graviton orbit, and absorption of gamma-rays in the magnetosphere of the NS. We compare our Monte Carlo-based differential flux to the experimental differential flux using maximum likelihood techniques to obtain our limits on LED. Our limits are more restrictive than past EGRET-based optimistic limits that do not include these important corrections. Additionally, our limits are more stringent than LHC based limits for 3 or fewer LED, and comparable for 4 LED. We conclude that if the effective Planck scale is around a TeV, then for 2 or 3 LED the compactification topology must be more complicated than a torus.

  8. Limits on Large Extra Dimensions Based on Observations of Neutron Stars with the Fermi-LAT

    NASA Technical Reports Server (NTRS)

    Ferrara, E. C.; Scargle, J. D.; Troja, E.

    2012-01-01

    We present limits for the compactification scale in the theory of Large Extra Dimensions (LED) proposed by Arkani-Hamed, Dimopoulos, and Dvali. We use 11 months of data from the Fermi Large Area Telescope (Fermi-LAT) to set gamma ray flux limits for 6 gamma-ray faint neutron stars (NS). To set limits on LED we use the model of Hannestad and Raffelt (HR) that calculates the Kaluza-Klein (KK) graviton production in supernova cores and the large fraction subsequently gravitationally bound around the resulting NS. The predicted decay of the bound KK gravitons to should contribute to the flux from NSs. Considering 2 to 7 extra dimensions of the same size in the context of the HR model, we use Monte Carlo techniques to calculate the expected differential flux of gamma-rays arising from these KK gravitons, including the effects of the age of the NS, graviton orbit, and absorption of gamma-rays in the magnetosphere of the NS. We compare our Monte Carlo-based differential flux to the experimental differential flux using maximum likelihood techniques to obtain our limits on LED. Our limits are more restrictive than past EGRET-based optimistic limits that do not include these important corrections. Additionally, our limits are more stringent than LHC based limits for 3 or fewer LED, and comparable for 4 LED. We conclude that if the effective Planck scale is around a TeV, then for 2 or 3 LED the compactification topology must be more complicated than a torus.

  9. Observable T{sub 7} Lepton Flavor Symmetry at the Large Hadron Collider

    SciTech Connect

    Cao Qinghong; Khalil, Shaaban; Ma, Ernest; Okada, Hiroshi

    2011-04-01

    More often than not, models of flavor symmetry rely on the use of nonrenormalizable operators (in the guise of flavons) to accomplish the phenomenologically successful tribimaximal mixing of neutrinos. We show instead how a simple renormalizable two-parameter neutrino mass model of tribimaximal mixing can be constructed with the non-Abelian discrete symmetry T{sub 7} and the gauging of B-L. This is also achieved without the addition of auxiliary symmetries and particles present in almost all other proposals. Most importantly, it is verifiable at the Large Hadron Collider.

  10. Spacewatch Observations of Asteroids and Comets Supporting the Large-Scale Surveys

    NASA Astrophysics Data System (ADS)

    McMillan, Robert S.; Bressi, Terrence H.; Scotti, James V.; Larsen, Jeffrey A.; Mastaler, Ronald A.

    2014-11-01

    We specialize in followup astrometry of Near-Earth Objects (NEOs) of high priority while they are faint, including recently discovered objects on the MPC's Confirmation Page, objects with potential close encounters with Earth, NEOs for which NEOWISE determined albedos and diameters, targets of radar, potential destinations for spacecraft, and special requests by the MPC or JPL. The present era of Spacewatch observations began on 2011 Oct 15 with a new imaging camera on our 1.8-meter telescope. From then, the MPC has been accepting an annual average of 8,492 lines of astrometry of 1,018 different NEOs from Spacewatch, including 177 different PHAs per year. Thus we observe half of all such objects that are observed by anyone in the same interval. We make twice as many measurements of PHAs while they are fainter than V=22 than the next most productive astrometry group. We have contributed to the removal of half of the objects that were retired from JPL's impact risk list. Per year we observe about 35 radar targets, 50 NEOs that were measured by NEOWISE, and 100 potential rendezvous destinations. We also average 400 observations of comets per year. Since 2004 we have increased our efficiency by a factor of six in terms of observations per unit personnel work year by means of new hardware, software, and the automation of the 0.9-m telescope. Last year we received a grant to upgrade our 0.9-m telescope and develop a public archive of image data dating back to 1990. New grants from the NEOO Program now support our use of telescopes larger than the 1.8-meter of Spacewatch and improvement of the efficiency of the Spacewatch 1.8-m. Support of Spacewatch was/is from JPL subcontract 100319 (2010-2011), NASA/NEOO grants NNG06GJ42G, NNX11AB52G, NNX12AG11G, NNX13AP99G, NNX14AL13G, and NNX14AL14G, the Lunar and Planetary Laboratory, Steward Observatory, the Brinson Foundation of Chicago, IL, the estates of R. S. Vail and R. L. Waland, and other private donors. We are also indebted

  11. Circular chemiresistors for microchemical sensors

    DOEpatents

    Ho, Clifford K.

    2007-03-13

    A circular chemiresistor for use in microchemical sensors. A pair of electrodes is fabricated on an electrically insulating substrate. The pattern of electrodes is arranged in a circle-filling geometry, such as a concentric, dual-track spiral design, or a circular interdigitated design. A drop of a chemically sensitive polymer (i.e., chemiresistive ink) is deposited on the insulating substrate on the electrodes, which spreads out into a thin, circular disk contacting the pair of electrodes. This circularly-shaped electrode geometry maximizes the contact area between the pair of electrodes and the polymer deposit, which provides a lower and more stable baseline resistance than with linear-trace designs. The circularly-shaped electrode pattern also serves to minimize batch-to-batch variations in the baseline resistance due to non-uniform distributions of conductive particles in the chemiresistive polymer film.

  12. Observing two dark accelerators around the Galactic Centre with Fermi Large Area Telescope

    NASA Astrophysics Data System (ADS)

    Hui, C. Y.; Yeung, P. K. H.; Ng, C. W.; Lin, L. C. C.; Tam, P. H. T.; Cheng, K. S.; Kong, A. K. H.; Chernyshov, D. O.; Dogiel, V. A.

    2016-04-01

    We report the results from a detailed γ-ray investigation in the field of two `dark accelerators', HESS J1745-303 and HESS J1741-302, with 6.9 yr of data obtained by the Fermi Large Area Telescope. For HESS J1745-303, we found that its MeV-GeV emission is mainly originated from the `Region A' of the TeV feature. Its γ-ray spectrum can be modelled with a single power law with a photon index of Γ ˜ 2.5 from few hundreds MeV-TeV. Moreover, an elongated feature, which extends from `Region A' towards north-west for ˜1.3°, is discovered for the first time. The orientation of this feature is similar to that of a large-scale atomic/molecular gas distribution. For HESS J1741-302, our analysis does not yield any MeV-GeV counterpart for this unidentified TeV source. On the other hand, we have detected a new point source, Fermi J1740.1-3013, serendipitously. Its spectrum is apparently curved which resembles that of a γ-ray pulsar. This makes it possibly associated with PSR B1737-20 or PSR J1739-3023.

  13. Large-scale outflow in quasar LBQS J1206+1052: HST/COS observations

    NASA Astrophysics Data System (ADS)

    Chamberlain, Carter; Arav, Nahum

    2015-11-01

    Using two orbits of HST/COS archival observations, we measure the location and energetics of a quasar outflow from LBQS J1206+1052. From separate collisional excitation models of observed N III/N III* and S III/S III* troughs, we measure the electron number density n_e of the outflow. Both independent determinations are in full agreement and yield n_e =10^{3.0} cm^{-3}. Combining this value of n_e with photoionization simulations, we determine that the outflow is located 840 pc from the central source. The outflow has a velocity of 1400 km s-1, a mass flux of 9 M⊙ yr-1 and a kinetic luminosity of 1042.8 erg s-1. The distance finding is much larger than predicted from radiative acceleration models, but is consistent with recent empirical distance determinations.

  14. Fermi large area telescope observations of blazar 3C 279 occultations by the sun

    SciTech Connect

    Barbiellini, G.; Bastieri, D.; Buson, S.; Bechtol, K.; Blandford, R. D.; Borgland, A. W.; Buehler, R.; Cameron, R. A.; Chiang, J.; Bellazzini, R.; Bregeon, J.; Bruel, P.; Caraveo, P. A.; Cavazzuti, E.; Ciprini, S.; Cecchi, C.; Chaves, R. C. G.; Cheung, C. C. E-mail: phdmitry@stanford.edu; and others

    2014-04-01

    Observations of occultations of bright γ-ray sources by the Sun may reveal predicted pair halos around blazars and/or new physics, such as, e.g., hypothetical light dark matter particles—axions. We use Fermi Gamma-Ray Space Telescope (Fermi) data to analyze four occultations of blazar 3C 279 by the Sun on October 8 each year from 2008 to 2011. A combined analysis of the observations of these occultations allows a point-like source at the position of 3C 279 to be detected with significance of ≈3σ, but does not reveal any significant excess over the flux expected from the quiescent Sun. The likelihood ratio test rules out complete transparency of the Sun to the blazar γ-ray emission at a 3σ confidence level.

  15. Observation of high-spin bands with large moments of inertia in Xe124

    DOE PAGES

    Nag, Somnath; Singh, A. K.; Hagemann, G. B.; ...

    2016-09-07

    In this paper, high-spin states in 124Xe have been populated using the 80Se(48Ca, 4n) reaction at a beam energy of 207 MeV and high-multiplicity, γ-ray coincidence events were measured using the Gammasphere spectrometer. Six high-spin rotational bands with moments of inertia similar to those observed in neighboring nuclei have been observed. The experimental results are compared with calculations within the framework of the Cranked Nilsson-Strutinsky model. Finally, it is suggested that the configurations of the bands involve excitations of protons across the Z = 50 shell gap coupled to neutrons within the N = 50 - 82 shell or excitedmore » across the N = 82 shell closure.« less

  16. Satellite Observed Widespread Decline in Mongolian Grasslands Largely Due to Overgrazing

    NASA Technical Reports Server (NTRS)

    Hilker, Thomas; Natsagdorj, Enkhjargal; Waring, Richard H.; Lyapustin, Alexei; Wang, Yujie

    2014-01-01

    The Mongolian Steppe is one of the largest remaining grassland ecosystems. Recent studies have reported widespread decline of vegetation across the steppe and about 70 percent of this ecosystem is now considered degraded. Among the scientific community there has been an active debate about whether the observed degradation is related to climate, or overgrazing, or both. Here, we employ a new atmospheric correction and cloud screening algorithm (MAIAC) to investigate trends in satellite observed vegetation phenology. We relate these trends to changes in climate and domestic animal populations. A series of harmonic functions is fitted to MODIS observed phenological curves to quantify seasonal and inter-annual changes in vegetation. Our results show a widespread decline (of about 12 percent on average) in MODIS observed NDVI across the country but particularly in the transition zone between grassland and the Gobi desert, where recent decline was as much as 40 percent below the 2002 mean NDVI. While we found considerable regional differences in the causes of landscape degradation, about 80 percent of the decline in NDVI could be attributed to increase in livestock. Changes in precipitation were able to explain about 30 percent of degradation across the country as a whole but up to 50 percent in areas with denser vegetation cover (p0.05). Temperature changes, while significant, played only a minor role (r20.10, p0.05). Our results suggest that the cumulative effect of overgrazing is a primary contributor to the degradation of the Mongolian steppe and is at least partially responsible for desertification reported in previous studies.

  17. Energetic delayed hadrons in large air showers observed at 5200m above sea level

    NASA Technical Reports Server (NTRS)

    Kaneko, T.; Hagiwara, K.; Yoshii, H.; Martinic, N.; Siles, L.; Miranda, P.; Kakimoto, F.; Tsuchimoto, I.; Inoue, N.; Suga, K.

    1985-01-01

    Energetic delayed hadrons in air showers with electron sizes in the range 10 to the 6th power to 10 to the 9th power were studied by observing the delayed bursts produced in the shield of nine square meter scintillation detectors in the Chacaltaya air-shower array. The frequency of such delayed burst is presented as a function of electron size, core distance and sec theta.

  18. Volcanic activity before and after large tectonic earthquakes: Observations and statistical significance

    NASA Astrophysics Data System (ADS)

    Eggert, Silke; Walter, Thomas R.

    2009-06-01

    The study of volcanic triggering and interaction with the tectonic surroundings has received special attention in recent years, using both direct field observations and historical descriptions of eruptions and earthquake activity. Repeated reports of clustered eruptions and earthquakes may imply that interaction is important in some subregions. However, the subregions likely to suffer such clusters have not been systematically identified, and the processes responsible for the observed interaction remain unclear. We first review previous works about the clustered occurrence of eruptions and earthquakes, and describe selected events. We further elaborate available databases and confirm a statistically significant relationship between volcanic eruptions and earthquakes on the global scale. Moreover, our study implies that closed volcanic systems in particular tend to be activated in association with a tectonic earthquake trigger. We then perform a statistical study at the subregional level, showing that certain subregions are especially predisposed to concurrent eruption-earthquake sequences, whereas such clustering is statistically less significant in other subregions. Based on this study, we argue that individual and selected observations may bias the perceptible weight of coupling. The activity at volcanoes located in the predisposed subregions (e.g., Japan, Indonesia, Melanesia), however, often unexpectedly changes in association with either an imminent or a past earthquake.

  19. MESSENGER Orbital Observations of Large-Amplitude Kelvin-Helmholtz Waves at Mercury's Magnetopause

    NASA Technical Reports Server (NTRS)

    Sundberg, Torbjorn; Boardsen, Scott A.; Slavin, James A.; Anderson, Brian J.; Korth, Haje; Zurbuchen, Thomas H.; Raines, Jim M.; Solomon, Sean C.

    2012-01-01

    We present a survey of Kelvi\\ n-Helmholtz (KH) waves at Mercury's magnetopause during MESSENGER's first Mercury year in orb it. The waves were identified on the basis of the well-established sawtooth wave signatures that are associated with non-linear KH vortices at the magnetopause. MESSENGER frequently observed such KH waves in the dayside region of the magnetosphere where the magnetosheath flow velocity is still sub -sonic, which implies that instability growth rates at Mercury's magnetopau are much larger than at Earth. We attribute these greater rates to the limited wave energy dissipation in Mercury's highly resistive regolith. The wave amplitude was often on the order of ' 00 nT or more, and the wave periods were - 10- 20 s. A clear dawn-dusk asymmetry is present in the data, in that all of the observed wave events occurred in the post-noon and dusk-side sectors of the magnetopause. This asymmetry is like ly related to finite Larmor-radius effects and is in agreement with results from particle-in-cell simulations of the instability. The waves were observed almost exclusively during periods when the north-south component of the magnetosheath magnetic field was northward, a pattern similar to that for most terrestrial KH wave events. Accompanying plasma measurements show that the waves were associated with the transport of magnetosheath plasma into the magnetosphere.

  20. Observation of ferroelectric phase and large spontaneous electric polarization in organic salt of diisopropylammonium iodide

    NASA Astrophysics Data System (ADS)

    Saripalli, Ravi K.; Swain, Diptikanta; Prasad, Siva; Nhalil, Hariharan; Bhat, Handady L.; Guru Row, Tayur N.; Elizabeth, Suja

    2017-03-01

    In this manuscript, we explore diisopropylammonium iodide (DPI) for its ferroelectric properties and phase transitions. DPI showed two phase transitions which were identified by differential scanning calorimetry and dielectric and nonlinear optical measurements. From detailed structural studies it was found that the first transition at 369 K is from orthorhombic P212121 to monoclinic P21. The polar P21 phase is ferroelectric as evidenced by the pyroelectric data and has a very high value of spontaneous polarization (Ps = 33 μC cm-2), which is probably the highest among other reported bulk organic ferroelectrics. The second transition at 415 K is identified as polar monoclinic P21 space group to non-polar monoclinic P21/m. Thus, DPI has a high Curie temperature of 415 K. The large spontaneous polarization and high Curie temperature make DPI technologically important.

  1. Large collaboration in observational astronomy: the Gemini Planet Imager exoplanet survey case

    NASA Astrophysics Data System (ADS)

    Marchis, Franck; Kalas, Paul G.; Perrin, Marshall D.; Konopacky, Quinn M.; Savransky, Dmitry; Macintosh, Bruce; Marois, Christian; Graham, James R.

    2016-08-01

    The Gemini Planet Imager (GPI) is a next-generation high-contrast imager built for the Gemini Observatory. The GPI exoplanet survey (GPIES) consortium is made up of 102 researchers from 28 institutions in North and South America and Europe. In November 2014, we launched a search for young Jovian planets and debris disks. In this paper, we discuss how we have coordinated the work done by this large team to improve the technical and scientific productivity of the campaign, and describe lessons we have learned that could be useful for future instrumentation-based astronomical surveys. The success of GPIES lies mostly on its decentralized structure, clear definition of policies that are signed by each member, and the heavy use of modern tools for communicating, exchanging information, and processing data.

  2. Large-Range Movements of Neotropical Orchid Bees Observed via Radio Telemetry

    PubMed Central

    Wikelski, Martin; Moxley, Jerry; Eaton-Mordas, Alexander; López-Uribe, Margarita M.; Holland, Richard; Moskowitz, David; Roubik, David W.; Kays, Roland

    2010-01-01

    Neotropical orchid bees (Euglossini) are often cited as classic examples of trapline-foragers with potentially extensive foraging ranges. If long-distance movements are habitual, rare plants in widely scattered locations may benefit from euglossine pollination services. Here we report the first successful use of micro radio telemetry to track the movement of an insect pollinator in a complex and forested environment. Our results indicate that individual male orchid bees (Exaerete frontalis) habitually use large rainforest areas (at least 42–115 ha) on a daily basis. Aerial telemetry located individuals up to 5 km away from their core areas, and bees were often stationary, for variable periods, between flights to successive localities. These data suggest a higher degree of site fidelity than what may be expected in a free living male bee, and has implications for our understanding of biological activity patterns and the evolution of forest pollinators. PMID:20520813

  3. Pan-chromatic observations of the remarkable nova Large Magellanic Cloud 2012

    SciTech Connect

    Schwarz, Greg J.; Shore, Steven N.; Page, Kim L.; Osborne, Julian P.; Beardmore, Andrew P.; Walter, Frederick M.; Bode, Michael F.; Drake, Jeremy J.; Ness, Jan-Uwe; Starrfield, Sumner; Rossum, Daniel R. Van; Woodward, Charles E.

    2015-03-01

    We present the results of an intensive multiwavelength campaign on nova LMC 2012. This nova evolved very rapidly in all observed wavelengths. The time to fall two magnitudes in the V band was only 2 days. In X-rays the super soft phase began 13 ± 5 days after discovery and ended around day 50 after discovery. During the super soft phase, the Swift/XRT and Chandra spectra were consistent with the underlying white dwarf (WD) being very hot, ∼1 MK, and luminous, ∼10{sup 38} erg s{sup −1}. The UV, optical, and near-IR photometry showed a periodic variation after the initial and rapid fading had ended. Timing analysis revealed a consistent 19.24 ± 0.03 hr period in all UV, optical, and near-IR bands with amplitudes of ∼0.3 mag which we associate with the orbital period of the central binary. No periods were detected in the corresponding X-ray data sets. A moderately high inclination system, i = 60 ± 10{sup ∘}, was inferred from the early optical emission lines. The HST/STIS UV spectra were highly unusual with only the N v (1240 Å) line present and superposed on a blue continuum. The lack of emission lines and the observed UV and optical continua from four epochs can be fit with a low mass ejection event, ∼10{sup −6} M{sub ⊙}, from a hot and massive WD near the Chandrasekhar limit. The WD, in turn, significantly illuminated its subgiant companion which provided the bulk of the observed UV/optical continuum emission at the later dates. The inferred extreme WD characteristics and low mass ejection event favor nova LMC 2012 being a recurrent nova of the U Sco subclass.

  4. Implementation and management of a biomedical observation dictionary in a large healthcare information system

    PubMed Central

    Vandenbussche, Pierre-Yves; Cormont, Sylvie; André, Christophe; Daniel, Christel; Delahousse, Jean; Charlet, Jean; Lepage, Eric

    2013-01-01

    Objective This study shows the evolution of a biomedical observation dictionary within the Assistance Publique Hôpitaux Paris (AP-HP), the largest European university hospital group. The different steps are detailed as follows: the dictionary creation, the mapping to logical observation identifier names and codes (LOINC), the integration into a multiterminological management platform and, finally, the implementation in the health information system. Methods AP-HP decided to create a biomedical observation dictionary named AnaBio, to map it to LOINC and to maintain the mapping. A management platform based on methods used for knowledge engineering has been put in place. It aims at integrating AnaBio within the health information system and improving both the quality and stability of the dictionary. Results This new management platform is now active in AP-HP. The AnaBio dictionary is shared by 120 laboratories and currently includes 50 000 codes. The mapping implementation to LOINC reaches 40% of the AnaBio entries and uses 26% of LOINC records. The results of our work validate the choice made to develop a local dictionary aligned with LOINC. Discussion and Conclusions This work constitutes a first step towards a wider use of the platform. The next step will support the entire biomedical production chain, from the clinician prescription, through laboratory tests tracking in the laboratory information system to the communication of results and the use for decision support and biomedical research. In addition, the increase in the mapping implementation to LOINC ensures the interoperability allowing communication with other international health institutions. PMID:23635601

  5. Volcanic activity before and after large tectonic earthquakes: Observations and statistical significance

    NASA Astrophysics Data System (ADS)

    Eggert, S.; Walter, T. R.

    2009-04-01

    The study of volcanic triggering and coupling to the tectonic surroundings has received special attention in recent years, using both direct field observations and historical descriptions of eruptions and earthquake activity. Repeated reports of volcano-earthquake interactions in, e.g., Europe and Japan, may imply that clustered occurrence is important in some regions. However, the regions likely to suffer clustered eruption-earthquake activity have not been systematically identified, and the processes responsible for the observed interaction are debated. We first review previous works about the correlation of volcanic eruptions and earthquakes, and describe selected local clustered events. Following an overview of previous statistical studies, we further elaborate the databases of correlated eruptions and earthquakes from a global perspective. Since we can confirm a relationship between volcanic eruptions and earthquakes on the global scale, we then perform a statistical study on the regional level, showing that time and distance between events follow a linear relationship. In the time before an earthquake, a period of volcanic silence often occurs, whereas in the time after, an increase in volcanic activity is evident. Our statistical tests imply that certain regions are especially predisposed to concurrent eruption-earthquake pairs, e.g., Japan, whereas such pairing is statistically less significant in other regions, such as Europe. Based on this study, we argue that individual and selected observations may bias the perceptible weight of coupling. Volcanoes located in the predisposed regions (e.g., Japan, Indonesia, Melanesia), however, indeed often have unexpectedly changed in association with either an imminent or a past earthquake.

  6. A Large Sample of Magnetically-Active Stars Observed With Kepler

    NASA Astrophysics Data System (ADS)

    Wells, Mark; Neff, J. E.; Brown, A.; Ayres, T. R.; Basri, G. S.; Berdyugina, S.; Harper, G.; Hawley, S. L.; Korhonen, H.; Kowalski, A.; Micela, G.; Piskunov, N. E.; Ramsey, L. W.; Saar, S. H.; Walkowicz, L. M.

    2013-01-01

    We have observed about 325 stars in our Kepler Guest Observer programs (Cycles 1 through 4). For most of these targets, we are analyzing extremely high-precision light curves that have been continuously sampled every 30 minutes for up to 3 years. Our sample of candidate magnetically-active stars was selected primarily using GALEX colors. Starspots, pulsations, and variations due to eclipsing and contact binaries combine to produce a rich variety of light curves. We have developed semi-automated procedures to characterize this variability and thus to classify the targets and identify the physical mechanisms that dominate their Kepler light curves. We will describe these procedures and discuss the range of physical properties covered by our final classification scheme. We are using this Kepler database of variability over timescales of minutes to years to provide diagnostics of flares, starspot formation, evolution, migration, and ultimately of stellar cycles in general. This work contains results obtained using the NASA Kepler satellite and from the Apache Point Observatory, the MMT (using NOAO community access time), and the Hobby-Eberly Telescope. Funding is provided by NASA Kepler grants NNX10AC51G, NNX11AC79G, and NNX12AC85G to the University of Colorado, by NSF grant AST-1109695 to the College of Charleston, and by a grant from the South Carolina Space Grant consortium.

  7. X-ray observations of a large sample of cataclysmic variable stars using the Einstein Observatory

    NASA Technical Reports Server (NTRS)

    Cordova, F. A.; Mason, K. O.

    1984-01-01

    This paper presents the results of an X-ray survey of 31 known or suspected cataclysmic variables. Eighteen of these close binary systems are detected with inferred luminosities in the 0.1-4.0 keV band of between 10 to the 30th and 10 to the 32nd erg/sec. The majority have relatively hard X-ray spectra (kT greater than 2 keV) irrespective of luminosity state. Of seven dwarf novae observed during optical outbursts only U Gem exhibited enhanced ultrasoft X-ray emission (kT of about 10 eV) in addition to weak, hard X-ray emission. Variability of the X-ray flux is observed in many of these stars, on time-scales ranging from tens of seconds to hours. The contribution to the flux from extended X-ray emission is investigated for SU UMa and GK Per. Several possibilities for the origin of the hard X-rays are considered.

  8. ESO Diffuse Interstellar Bands Large Exploration Survey (EDIBLES) - Merging Observations and Laboratory Data

    NASA Technical Reports Server (NTRS)

    Salama, Farid

    2016-01-01

    The Diffuse Interstellar Bands (DIBs) are a set of 500 absorption bands that are detected in the spectra of stars with interstellar clouds in the line of sight. DIBs are found from the NUV to the NIR in the spectra of reddened stars spanning different interstellar environments in our local, and in other galaxies. DIB carriers are a significant part of the interstellar chemical inventory. They are stable and ubiquitous in a broad variety of environments and play a unique role in interstellar physics/chemistry. It has long been realized that the solving of the DIB problem requires a strong synergy between astronomical observations, laboratory astrophysics, and astrophysical modeling of line-of-sights. PAHs are among the molecular species that have been proposed as DIB carriers. We will present an assessment of the PAH-DIB model in view of the progress and the advances that have been achieved over the past years through a series of studies involving astronomical observations of DIBs, laboratory simulation of interstellar analogs for neutrals and ionized PAHs, theoretical calculations of PAH spectra and the modelization of diffuse and translucent interstellar clouds. We will present a summary of what has been learned from these complementary studies, the constraints that can now be derived for the PAHs as DIB carriers in the context of the PAH-DIB model and how these constraints can be applied to the EDIBLES project. The spectra of several neutral and ionized PAHs isolated in the gas phase at low temperature have been measured in the laboratory under experimental conditions that mimic interstellar conditions and are compared with an extensive set of astronomical spectra of reddened, early type stars. The comparisons of astronomical and laboratory data provide upper limits for the abundances of specific neutral PAH molecules and ions along specific lines-of-sight. Something that is not attainable from infrared observations alone. We present the characteristics of the

  9. Recent Large Reduction in Sulfur Dioxide Emissions from Chinese Power Plants Observed by the Ozone Monitoring Instrument

    NASA Technical Reports Server (NTRS)

    Li, Can; Zhang, Qiang; Krotkov, Nickolay A.; Streets, David G.; He, Kebin; Tsay, Si-Chee; Gleason, James F.

    2010-01-01

    The Ozone Monitoring Instrument (OMI) aboard NASA's Aura satellite observed substantial increases in total column SO2 and tropospheric column NO2 from 2005 to 2007, over several areas in northern China where large coal-fired power plants were built during this period. The OMI-observed SO2/NO2 ratio is consistent with the SO2/ NO2, emissions estimated from a bottom-up approach. In 2008 over the same areas, OMI detected little change in NO2, suggesting steady electricity output from the power plants. However, dramatic reductions of S0 2 emissions were observed by OMI at the same time. These reductions confirm the effectiveness of the flue-gas desulfurization (FGD) devices in reducing S02 emissions, which likely became operational between 2007 and 2008. This study further demonstrates that the satellite sensors can monitor and characterize anthropogenic emissions from large point sources.

  10. Nuclear spin circular dichroism

    SciTech Connect

    Vaara, Juha; Rizzo, Antonio; Kauczor, Joanna; Norman, Patrick; Coriani, Sonia

    2014-04-07

    Recent years have witnessed a growing interest in magneto-optic spectroscopy techniques that use nuclear magnetization as the source of the magnetic field. Here we present a formulation of magnetic circular dichroism (CD) due to magnetically polarized nuclei, nuclear spin-induced CD (NSCD), in molecules. The NSCD ellipticity and nuclear spin-induced optical rotation (NSOR) angle correspond to the real and imaginary parts, respectively, of (complex) quadratic response functions involving the dynamic second-order interaction of the electron system with the linearly polarized light beam, as well as the static magnetic hyperfine interaction. Using the complex polarization propagator framework, NSCD and NSOR signals are obtained at frequencies in the vicinity of optical excitations. Hartree-Fock and density-functional theory calculations on relatively small model systems, ethene, benzene, and 1,4-benzoquinone, demonstrate the feasibility of the method for obtaining relatively strong nuclear spin-induced ellipticity and optical rotation signals. Comparison of the proton and carbon-13 signals of ethanol reveals that these resonant phenomena facilitate chemical resolution between non-equivalent nuclei in magneto-optic spectra.

  11. Keplerian integrals, elimination theory and identification of very short arcs in a large database of optical observations

    NASA Astrophysics Data System (ADS)

    Gronchi, G. F.; Baù, G.; Milani, A.

    2017-02-01

    Modern asteroid surveys produce an increasingly large number of observations, which are grouped into very short arcs (VSAs) each containing a few observations of the same object in one single night. To decide whether two VSAs collected in different nights correspond to the same observed object we can attempt to compute an orbit with the observations of both arcs: this is called the linkage problem. Since the number of linkages to be attempted is very large, we need efficient methods of orbit determination. Using the first integrals of Kepler's motion we can write algebraic equations for the linkage problem, which can be put in polynomial form. In Gronchi et al. (Celest Mech Dyn Astron 123(2):105-122, 2015) these equations are reduced to a polynomial equation of degree 9: the unknown is the topocentric distance of the observed body at the mean epoch of one VSA. Here we derive the same equations in a more concise way, and show that the degree 9 is optimal in a sense that will be specified in Sect. 3.3. We also introduce a procedure to join three VSAs: from the conservation of angular momentum we obtain a polynomial equation of degree 8 in the topocentric distance at the mean epoch of the second VSA. For both identification methods, with two and three VSAs, we discuss how to discard solutions. Finally, we present some numerical tests showing that the new methods give satisfactory results and can be used also when the time separation between the VSAs is large. The low polynomial degree of the new methods makes them well suited to deal with the very large number of asteroid observations collected by the modern surveys.

  12. Melt production in large-scale impact events: Implications and observations at terrestrial craters

    NASA Technical Reports Server (NTRS)

    Grieve, Richard A. F.; Cintala, Mark J.

    1992-01-01

    The volume of impact melt relative to the volume of the transient cavity increases with the size of the impact event. Here, we use the impact of chondrite into granite at 15, 25, and 50 km s(sup -1) to model impact-melt volumes at terrestrial craters in crystalline targets and explore the implications for terrestrial craters. Figures are presented that illustrate the relationships between melt volume and final crater diameter D(sub R) for observed terrestrial craters in crystalline targets; also included are model curves for the three different impact velocities. One implication of the increase in melt volumes with increasing crater size is that the depth of melting will also increase. This requires that shock effects occurring at the base of the cavity in simple craters and in the uplifted peaks of central structures at complex craters record progressively higher pressures with increasing crater size, up to a maximum of partial melting (approx. 45 GPa). Higher pressures cannot be recorded in the parautochthonous rocks of the cavity floor as they will be represented by impact melt, which will not remain in place. We have estimated maximum recorded pressures from a review of the literature, using such observations as planar features in quartz and feldspar, diaplectic glasses of feldspar and quartz, and partial fusion and vesiculation, as calibrated with estimates of the pressures required for their formation. Erosion complicates the picture by removing the surficial (most highly shocked) rocks in uplifted structures, thereby reducing the maximum shock pressures observed. In addition, the range of pressures that can be recorded is limited. Nevertheless, the data define a trend to higher recorded pressures with crater diameter, which is consistent with the implications of the model. A second implication is that, as the limit of melting intersects the base of the cavity, central topographic peaks will be modified in appearance and ultimately will not occur. That is

  13. OBSERVATIONS OF ENERGETIC HIGH MAGNETIC FIELD PULSARS WITH THE FERMI LARGE AREA TELESCOPE

    SciTech Connect

    Parent, D.; Abdo, A. A.; Kerr, M.; Den Hartog, P. R.; Romani, R. W.; Watters, K.; Craig, H. A.; Baring, M. G.; DeCesar, M. E.; Harding, A. K.; Espinoza, C. M.; Stappers, B. W.; Weltevrede, P.; Gotthelf, E. V.; Camilo, F.; Johnston, S.; Kaspi, V. M.; Livingstone, M.; Burgay, M.; Freire, P. C. C. E-mail: kerrm@stanford.edu; and others

    2011-12-20

    We report the detection of {gamma}-ray pulsations from the high-magnetic-field rotation-powered pulsar PSR J1119-6127 using data from the Fermi Large Area Telescope. The {gamma}-ray light curve of PSR J1119-6127 shows a single, wide peak offset from the radio peak by 0.43 {+-} 0.02 in phase. Spectral analysis suggests a power law of index 1.0 {+-} 0.3{sup +0.4}{sub -0.2} with an energy cutoff at 0.8 {+-} 0.2{sup +2.0}{sub -0.5} GeV. The first uncertainty is statistical and the second is systematic. We discuss the emission models of PSR J1119-6127 and demonstrate that despite the object's high surface magnetic field-near that of magnetars-the field strength and structure in the {gamma}-ray emitting zone are apparently similar to those of typical young pulsars. Additionally, we present upper limits on the {gamma}-ray pulsed emission for the magnetically active PSR J1846-0258 in the supernova remnant Kesteven 75 and two other energetic high-B pulsars, PSRs J1718-3718 and J1734-3333. We explore possible explanations for the non-detection of these three objects, including peculiarities in their emission geometry.

  14. The breakup of large tabular icebergs - direct observations and theoretical considerations

    NASA Astrophysics Data System (ADS)

    Wadhams, P.

    2013-12-01

    Peter Wadhams and Till Wagner Dept. of Applied Mathematics and Theoretical Physics (DAMTP), University of Cambridge. We review the factors governing the stability, dynamics and decay of icebergs and describe areas where current models are inadequate. These include questions such as draft changes in capsizing icebergs; iceberg trajectory modelling; the melt rate of the ice underside and ways of reducing it; and wave-induced flexure and its role in the break-up of tabular icebergs. In July 2012 the authors worked on a very large (42 sq km) tabular iceberg in Baffin Bay, which had calved from the Petermann Glacier in NW Greenland. We measured incoming swell spectrum and the iceberg response; also the role of buoyancy forces due to erosion of a waterline wave cut and the creation of an underwater ram. The iceberg broke up while we were on it, allowing an instrumental measurement of the calving event. The experiments were included in the BBC-2 film 'Operation Iceberg' shown on Nov 1 2012 and repeated on Nov 18. We conclude that two processes interacted in the break-up event: increased bending stress due to buoyancy of underwater rams; and direct flexural strain due to incidence of ocean swell. Implications for icebergs in the open sea are estimated.

  15. Observations of four types of pulses in a fiber laser with large net-normal dispersion.

    PubMed

    Wang, Leiran; Liu, Xueming; Gong, Yongkang; Mao, Dong; Duan, Lina

    2011-04-11

    Four different types of pulses are experimentally obtained in one erbium-doped all-fiber laser with large net-normal dispersion. The proposed laser can deliver the rectangular-spectrum (RS), Gaussian-spectrum (GS), broadband-spectrum (BS), and noise-like pulses by appropriately adjusting the polarization states. These kinds of pulses have distinctly different characteristics. The RS pulses can easily be compressed to femtosecond level whereas the pulse energy is restricted by the trend of multi-pulse shaping with excessive pump. The GS and BS pulses always maintain the single-pulse operation with much higher pulse-energy and accumulate much more chirp. After launching the pulses into the photonic-crystal fiber, the supercontinuum can be generated with the bandwidth of >700 nm by the BS pulses and of ~400 nm by the GS pulses, whereas it can hardly be generated by the RS pulses. The physical mechanisms behind the continuum generation are qualitatively investigated relating to different operating regimes. This work could help to a deeper insight of the normal-dispersion pulses.

  16. Proper motion of the Large Magellanic Cloud and the mass of the galaxy. 1: Observational results

    NASA Astrophysics Data System (ADS)

    Jones, B. F.; Klemola, A. R.; Lin, D. N. C.

    1994-04-01

    We have measured the proper motion of the Large Magellanic Cloud (LMC) using 21 plates taken with the Cerro-Tololo Inter-American Observatory (CTIO) 4 m telescope and covering an epoch span of 14 yr. The plates were centered on the globular cluster NGC 2257, lying on the northeast periphery of the Cloud. Proper motions were determined for 251 LMC members, chosen on the basis of the photometry of Stryker (1984), using 92 galaxies as a reference frame. The measured mean absolute proper motion of the LMC stars in our region is mualpha = 0.120 sec +/- 0.028 sec century-1, mudelta=0.026 sec +/- 0.027 sec century-1. After correcting for the rotation of the LMC and the effects of solar motion, this proper motion combined with the radial velocity of the LMC implies a galactocentric coordinate radial velocity for the Cloud of 48 +/- 41 km s-1 and a total galactocentric transverse velocity of 215 +/- 48 km s-1.

  17. Coordinated phenotype switching with large-scale chromosome flip-flop inversion observed in bacteria.

    PubMed

    Cui, Longzhu; Neoh, Hui-min; Iwamoto, Akira; Hiramatsu, Keiichi

    2012-06-19

    Genome inversions are ubiquitous in organisms ranging from prokaryotes to eukaryotes. Typical examples can be identified by comparing the genomes of two or more closely related organisms, where genome inversion footprints are clearly visible. Although the evolutionary implications of this phenomenon are huge, little is known about the function and biological meaning of this process. Here, we report our findings on a bacterium that generates a reversible, large-scale inversion of its chromosome (about half of its total genome) at high frequencies of up to once every four generations. This inversion switches on or off bacterial phenotypes, including colony morphology, antibiotic susceptibility, hemolytic activity, and expression of dozens of genes. Quantitative measurements and mathematical analyses indicate that this reversible switching is stochastic but self-organized so as to maintain two forms of stable cell populations (i.e., small colony variant, normal colony variant) as a bet-hedging strategy. Thus, this heritable and reversible genome fluctuation seems to govern the bacterial life cycle; it has a profound impact on the course and outcomes of bacterial infections.

  18. Large scale landslide mud flow modeling, simulation, and comparison with observations

    NASA Astrophysics Data System (ADS)

    Liu, F.; Shao, X.; Zhang, B.

    2012-12-01

    Landslide is a catastrophic natural event. Modeling, simulation, and early warning of landslide event can protect the safety of lives and properties. Therefore, study of landslide bears important scientific and practical value. In this research, we constructed a high performance parallel fluid dynamics model to study large scale landslide transport and evolution process. This model solves shallow water equation derived from 3 dimensional Euler equations in Cartesian coordinate system. Based on bottom topography, initial condition, bottom friction, and mudflow viscosity coefficient, density and other parameters, this model predicts landslide transport process and deposition distribution. Using 3 dimension bottom topography data from an digital elevation model in Zhou Qu area, this model produces the onset, transport and deposition process happened during Zhou Qu landslide. It also calculates spatial and temporal distribution of the mud flow transportation route, deposition depth, and kinematic energy of the event. This model together with an early warning system can lead to significant improvement to construction planning in landslide susceptible area.; Zhou Qu topography from Digital Elevation Model ; Modeling result from PLM (parallel landslide model)

  19. Constraints on axions and axionlike particles from Fermi Large Area Telescope observations of neutron stars

    NASA Astrophysics Data System (ADS)

    Berenji, B.; Gaskins, J.; Meyer, M.

    2016-02-01

    We present constraints on the nature of axions and axionlike particles (ALPs) by analyzing gamma-ray data from neutron stars using the Fermi Large Area Telescope. In addition to axions solving the strong C P problem of particle physics, axions and ALPs are also possible dark matter candidates. We investigate axions and ALPs produced by nucleon-nucleon bremsstrahlung within neutron stars. We derive a phenomenological model for the gamma-ray spectrum arising from subsequent axion decays. By analyzing five years of gamma-ray data (between 60 and 200 MeV) for a sample of four nearby neutron stars, we do not find evidence for an axion or ALP signal; thus we obtain a combined 95% confidence level upper limit on the axion mass of 7.9 ×10-2 eV , which corresponds to a lower limit for the Peccei-Quinn scale fa of 7.6 ×107 GeV . Our constraints are more stringent than previous results probing the same physical process, and are competitive with results probing axions and ALPs by different mechanisms.

  20. Hadronic effects and observables in B →π ℓ+ℓ- decay at large recoil

    NASA Astrophysics Data System (ADS)

    Hambrock, Christian; Khodjamirian, Alexander; Rusov, Aleksey

    2015-10-01

    We calculate the amplitude of the rare flavor-changing neutral-current decay B →π ℓ+ℓ- at large recoil of the pion. The nonlocal contributions in which the weak effective operators are combined with the electromagnetic lepton-pair emission are systematically taken into account. These amplitudes are calculated at off-shell values of the lepton-pair mass squared, q2<0 , employing the operator-product expansion, QCD factorization and light-cone sum rules. The results are fitted to hadronic dispersion relations in q2, including the intermediate vector meson contributions. The dispersion relations are then used in the physical region q2>0 . Our main result is the process-dependent addition Δ C9(B π )(q2) to the Wilson coefficient C9 obtained at 4 mℓ2

  1. H2 emission as a tracer of molecular hydrogen: Large-scale observations of Orion

    NASA Technical Reports Server (NTRS)

    Luhman, M. L.; Jaffe, D. T.; Keller, L. D.; Pak, Soojong

    1994-01-01

    We have detected extremely extended (greater than 1.5 deg, or 12 pc) near-infrared H2 line emission from the Orion A molecular cloud. We have mapped emission in the 1.601 micrometer(s) upsilon = 6 - 4 Q(1) and 2.121 micrometer(s) upsilon = 1 - 0 S(1) lines of H2 along a approx. 2 deg R.A. cut and from a 6' x 6' region near theta(sup 1) Ori C. The surface brightness of the extended H2 line emission is 10(exp -6) to 10(exp -5) ergs/s/sq. cm/sr. Based on the distribution and relative strengths of the H2 lines, we conclude that UV fluorescene is most likely the dominant H2 emission mechanism in the outer parts of the Orion cloud. Shock-heated gas does not make a major contribution to the H2 emission in this region. The fluorescent component of the total H2 upsilon = 1 - 0 S(1) luminosity from Orion is 30-40 solar luminosity. Molecular hydrogen excited by UV radiation from nearby OB stars contributes 98%-99% of the global H2 line emission from the Orion molecular cloud, even though this cloud has a powerful shock-excited H2 source in its core. The ability to detect large-scale H2 directly opens up new possibilities for the study of molecular clouds.

  2. Fermi Large Area Telescope Observations of the Cygnus Loop Supernova Remnant

    SciTech Connect

    Katagiri, H.; Tibaldo, L.; Ballet, J.; Giordano, F.; Grenier, I.A.; Porter, T.A.; Roth, M.; Tibolla, O.; Uchiyama, Y.; Yamazaki, R.; /Sagamihara, Aoyama Gakuin U.

    2011-11-08

    We present an analysis of the gamma-ray measurements by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope in the region of the supernova remnant (SNR) Cygnus Loop (G74.0-8.5). We detect significant gamma-ray emission associated with the SNR in the energy band 0.2-100 GeV. The gamma-ray spectrum shows a break in the range 2-3 GeV. The gamma-ray luminosity is {approx} 1 x 10{sup 33} erg s{sup -1} between 1-100 GeV, much lower than those of other GeV-emitting SNRs. The morphology is best represented by a ring shape, with inner/outer radii 0{sup o}.7 {+-} 0{sup o}.1 and 1{sup o}.6 {+-} 0{sup o}.1. Given the association among X-ray rims, H{alpha} filaments and gamma-ray emission, we argue that gamma rays originate in interactions between particles accelerated in the SNR and interstellar gas or radiation fields adjacent to the shock regions. The decay of neutral pions produced in nucleon-nucleon interactions between accelerated hadrons and interstellar gas provides a reasonable explanation for the gamma-ray spectrum.

  3. Observations of Energetic High Magnetic Field Pulsars with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Parent, D.; Kerr, M.; DenHartog, P. R.; Baring, M. G.; DeCesar, M. E.; Espinoza, C. M.; Harding, A. K.; Romani, R. W.; Stappers, B. W.; Watters, K.; Weltevrde, P.; Abdo, A. A.; Craig, H. A.; Kramer, M.; Lyne, A. G.

    2011-01-01

    We report the detection of gamma-ray pulsations from the high-magnetic-field rotation-powered pulsar PSR J1119.6127 using data from the Fermi Large Area Telescope. The gamma-ray light curve of PSR J1119.6127 shows a single, wide peak offset from the radio peak by 0.43 +/- 0.02 in phase. Spectral analysis suggests a power law of index 1.0 +/- 0.3(+0.4 -0.2) with an energy cut-off at 0.8 +/- 0.2(+2.0 -0.5) GeV. The first uncertainty is statistical and the second is systematic. We discuss the emission models of PSR J1119.6127 and demonstrate that despite the object's high surface magnetic field--near that of magnetars -- the field strength and structure in the gamma-ray emitting zone are apparently similar to those of typical young pulsars. Additionally, we present upper limits on the gamma-ray pulsed emission for the magnetically active PSR J1846.0258 in the supernova remnant Kesteven 75 and two other energetic high-Beta pulsars, PSRs J1718.3718 and J1734.3333. We explore possible explanations for the non-detection of these three objects, including peculiarities in their emission geometry.

  4. Epidemiology of multiple sclerosis: results from a large observational study in the UK.

    PubMed

    Jick, Susan S; Li, L; Falcone, G J; Vassilev, Z P; Wallander, M-A

    2015-09-01

    Multiple sclerosis (MS) progression to mortality may not be solely determined by the underlying autoimmune process. We conducted a study in a large cohort of MS patients with the aim of describing characteristics of MS patients and identification of predictors for all-cause mortality in this patient group. We performed a retrospective analysis of primary care data from the UK Clinical Practice Research Datalink. Incident MS cases diagnosed between 1993 and 2006 were identified and validated using electronic and original medical records. Patients were followed to identify deaths; hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional regression with age as time-scale. In total, 1713 incident MS cases were identified. Following MS diagnosis, frequent comorbidities were infections (80%), and depression (46%). Adjusted HRs (95% CIs) for all-cause mortality were: 2.0 (1.2-3.4) for current smoking; 7.6 (3.2-17.7) for alcohol abuse; 2.7 (1.6-4.5) for pneumonia and influenza; 4.1 (2.7-6.3) for urinary tract infections; 2.2 (1.2-4.2) for heart disease and 4.9 (2.9-8.0) for cancer. Our results suggest that MS survival is influenced not only by the underlying autoimmune process, but also by patient comorbidities and lifestyle factors.

  5. Ensemble learning of inverse probability weights for marginal structural modeling in large observational datasets.

    PubMed

    Gruber, Susan; Logan, Roger W; Jarrín, Inmaculada; Monge, Susana; Hernán, Miguel A

    2015-01-15

    Inverse probability weights used to fit marginal structural models are typically estimated using logistic regression. However, a data-adaptive procedure may be able to better exploit information available in measured covariates. By combining predictions from multiple algorithms, ensemble learning offers an alternative to logistic regression modeling to further reduce bias in estimated marginal structural model parameters. We describe the application of two ensemble learning approaches to estimating stabilized weights: super learning (SL), an ensemble machine learning approach that relies on V-fold cross validation, and an ensemble learner (EL) that creates a single partition of the data into training and validation sets. Longitudinal data from two multicenter cohort studies in Spain (CoRIS and CoRIS-MD) were analyzed to estimate the mortality hazard ratio for initiation versus no initiation of combined antiretroviral therapy among HIV positive subjects. Both ensemble approaches produced hazard ratio estimates further away from the null, and with tighter confidence intervals, than logistic regression modeling. Computation time for EL was less than half that of SL. We conclude that ensemble learning using a library of diverse candidate algorithms offers an alternative to parametric modeling of inverse probability weights when fitting marginal structural models. With large datasets, EL provides a rich search over the solution space in less time than SL with comparable results.

  6. Spitzer observations of dust emission from H II regions in the Large Magellanic Cloud

    SciTech Connect

    Stephens, Ian W.; Evans, Jessica Marie; Xue, Rui; Chu, You-Hua; Gruendl, Robert A.; Segura-Cox, Dominique M.

    2014-04-01

    Massive stars can alter physical conditions and properties of their ambient interstellar dust grains via radiative heating and shocks. The H II regions in the Large Magellanic Cloud (LMC) offer ideal sites to study the stellar energy feedback effects on dust because stars can be resolved, and the galaxy's nearly face-on orientation allows us to unambiguously associate H II regions with their ionizing massive stars. The Spitzer Space Telescope survey of the LMC provides multi-wavelength (3.6-160 μm) photometric data of all H II regions. To investigate the evolution of dust properties around massive stars, we have analyzed spatially resolved IR dust emission from two classical H II regions (N63 and N180) and two simple superbubbles (N70 and N144) in the LMC. We produce photometric spectral energy distributions (SEDs) of numerous small subregions for each region based on its stellar distributions and nebular morphologies. We use DustEM dust emission model fits to characterize the dust properties. Color-color diagrams and model fits are compared with the radiation field (estimated from photometric and spectroscopic surveys). Strong radial variations of SEDs can be seen throughout the regions, reflecting the available radiative heating. Emission from very small grains drastically increases at locations where the radiation field is the highest, while polycyclic aromatic hydrocarbons (PAHs) appear to be destroyed. PAH emission is the strongest in the presence of molecular clouds, provided that the radiation field is low.

  7. Direct observation shows superposition and large scale flexibility within cytoplasmic dynein motors moving along microtubules

    NASA Astrophysics Data System (ADS)

    Imai, Hiroshi; Shima, Tomohiro; Sutoh, Kazuo; Walker, Matthew L.; Knight, Peter J.; Kon, Takahide; Burgess, Stan A.

    2015-09-01

    Cytoplasmic dynein is a dimeric AAA+ motor protein that performs critical roles in eukaryotic cells by moving along microtubules using ATP. Here using cryo-electron microscopy we directly observe the structure of Dictyostelium discoideum dynein dimers on microtubules at near-physiological ATP concentrations. They display remarkable flexibility at a hinge close to the microtubule binding domain (the stalkhead) producing a wide range of head positions. About half the molecules have the two heads separated from one another, with both leading and trailing motors attached to the microtubule. The other half have the two heads and stalks closely superposed in a front-to-back arrangement of the AAA+ rings, suggesting specific contact between the heads. All stalks point towards the microtubule minus end. Mean stalk angles depend on the separation between their stalkheads, which allows estimation of inter-head tension. These findings provide a structural framework for understanding dynein's directionality and unusual stepping behaviour.

  8. Direct observation shows superposition and large scale flexibility within cytoplasmic dynein motors moving along microtubules

    PubMed Central

    Imai, Hiroshi; Shima, Tomohiro; Sutoh, Kazuo; Walker, Matthew L.; Knight, Peter J.; Kon, Takahide; Burgess, Stan A.

    2015-01-01

    Cytoplasmic dynein is a dimeric AAA+ motor protein that performs critical roles in eukaryotic cells by moving along microtubules using ATP. Here using cryo-electron microscopy we directly observe the structure of Dictyostelium discoideum dynein dimers on microtubules at near-physiological ATP concentrations. They display remarkable flexibility at a hinge close to the microtubule binding domain (the stalkhead) producing a wide range of head positions. About half the molecules have the two heads separated from one another, with both leading and trailing motors attached to the microtubule. The other half have the two heads and stalks closely superposed in a front-to-back arrangement of the AAA+ rings, suggesting specific contact between the heads. All stalks point towards the microtubule minus end. Mean stalk angles depend on the separation between their stalkheads, which allows estimation of inter-head tension. These findings provide a structural framework for understanding dynein's directionality and unusual stepping behaviour. PMID:26365535

  9. E(k)∝ k-5 observed at large k for rapidly rotating turbulent flow*

    NASA Astrophysics Data System (ADS)

    Swinney, Harry L.; Jung, Sungwhan; Yarbrough, Ray

    2004-11-01

    We have made velocity measurements on a quasi-two-dimensional turbulent flow in a rapidly rotating annulus (Reynolds number 20000, Rossby number 0.03). Earlier measurements demonstrated that in the inverse cascade (low wavenumbers), the energy scaling is given by E(k)∝ k-2 rather than the expected E(k)∝ k-5/3 [1]. Extending the measurements to high wavenumbers (into the forward enstrophy cascade), we find E(k)∝ k-5 rather than the E(k)∝ k-3 that has been found for a non-rotating quasi-two-dimensional flow [2]. Our observed value of -5 for the exponent is the same as a recently predicted bound for the exponent [3]. *Supported by ONR [1] C. N. Baroud et al., Phys. Rev. Lett. 88, 114501 (2002). [2] J. Paret and P. Tabeling, Phys. Fluids 10, 3126 (1998). [3] C. V. Tran and J. Bowman, Phys. Rev. E 69, 036303 (2004).

  10. Melt production in large-scale impact events: Planetary observations and implications

    NASA Technical Reports Server (NTRS)

    Cintala, Mark J.; Grieve, Richard A. F.

    1992-01-01

    Differences in scaling relationships for crater formation and the generation of impact melt should lead to a variety of observable features and phenomena. These relationships infer that the volume of the transient cavity (and final crater) relative to the volume of impact melt (and the depth to which melting occurs) decreases as the effects of gravity and impact velocity increase. Since planetary gravity and impact velocity are variables in the calculation of cavity and impact-melt volumes, the implications of the model calculation will vary between planetary bodies. Details of the model calculations of impact-melt generation as a function of impact and target physical conditions were provided elsewhere, as were attempts to validate the model through ground-truth data on melt volumes, shock attenuation, and morphology from terrestrial impact craters.

  11. The Asthma Mobile Health Study, a large-scale clinical observational study using ResearchKit.

    PubMed

    Chan, Yu-Feng Yvonne; Wang, Pei; Rogers, Linda; Tignor, Nicole; Zweig, Micol; Hershman, Steven G; Genes, Nicholas; Scott, Erick R; Krock, Eric; Badgeley, Marcus; Edgar, Ron; Violante, Samantha; Wright, Rosalind; Powell, Charles A; Dudley, Joel T; Schadt, Eric E

    2017-04-01

    The feasibility of using mobile health applications to conduct observational clinical studies requires rigorous validation. Here, we report initial findings from the Asthma Mobile Health Study, a research study, including recruitment, consent, and enrollment, conducted entirely remotely by smartphone. We achieved secure bidirectional data flow between investigators and 7,593 participants from across the United States, including many with severe asthma. Our platform enabled prospective collection of longitudinal, multidimensional data (e.g., surveys, devices, geolocation, and air quality) in a subset of users over the 6-month study period. Consistent trending and correlation of interrelated variables support the quality of data obtained via this method. We detected increased reporting of asthma symptoms in regions affected by heat, pollen, and wildfires. Potential challenges with this technology include selection bias, low retention rates, reporting bias, and data security. These issues require attention to realize the full potential of mobile platforms in research and patient care.

  12. Entropic derivation of F=ma for circular motion

    NASA Astrophysics Data System (ADS)

    Duncan, Michael; Singleton, Douglas; Myrzakulov, Ratbay

    2011-11-01

    We examine the entropic picture of Newton's second law for the case of circular motion. It is shown that one must make modifications to the derivation of F = ma due to a change in the effective Unruh temperature for circular motion. These modifications present a challenge to the entropic derivation of Newton's second law, but also open up the possibility to experimentally test and constrain this model for large centripetal accelerations. (Phys. Lett. B 703 (2011) 516-518)

  13. Entropic derivation of F = m a for circular motion

    NASA Astrophysics Data System (ADS)

    Duncan, Michael; Myrzakulov, Ratbay; Singleton, Douglas

    2011-09-01

    We examine the entropic picture of Newton's second law for the case of circular motion. It is shown that one must make modifications to the derivation of F = ma due to a change in the effective Unruh temperature for circular motion. These modifications present a challenge to the entropic derivation of Newton's second law, but also open up the possibility to experimentally test and constrain this model for large centripetal accelerations.

  14. Suppressed Magnetic Circular Dichroism and Valley-Selective Magnetoabsorption due to the Effective Mass Anisotropy in Bismuth

    NASA Astrophysics Data System (ADS)

    de Visser, Pieter J.; Levallois, Julien; Tran, Michaël K.; Poumirol, Jean-Marie; Nedoliuk, Ievgeniia O.; Teyssier, Jérémie; Uher, Ctirad; van der Marel, Dirk; Kuzmenko, Alexey B.

    2016-07-01

    We measure the far-infrared reflectivity and Kerr angle spectra on a high-quality crystal of pure semimetallic bismuth as a function of magnetic field, from which we extract the conductivity for left- and right-handed circular polarizations. The high spectral resolution allows us to separate the intraband Landau level transitions for electrons and holes. The hole transition exhibits 100% magnetic circular dichroism; it appears only for one polarization as expected for a circular cyclotron orbit. However, the dichroism for electron transitions is reduced to only 13 ±1 %, which is quantitatively explained by the large effective mass anisotropy of the electron pockets of the Fermi surface. This observation is a signature of the mismatch between the metric experienced by the photons and the electrons. It allows for a contactless measurement of the effective mass anisotropy and provides a direction towards valley polarized magnetooptical pumping with elliptically polarized light.

  15. THE FAINTEST RADIO SOURCE YET: EXPANDED VERY LARGE ARRAY OBSERVATIONS OF THE GRAVITATIONAL LENS SDSS J1004+4112

    SciTech Connect

    Jackson, N.

    2011-09-20

    We present new radio observations of the large-separation gravitationally lensed quasar SDSS J1004+4112, taken in a total of 6 hr of observations with the Expanded Very Large Array. The maps reach a thermal noise level of approximately 4 {mu}Jy. We detect four of the five lensed images at the 15-35 {mu}Jy level, representing a source of intrinsic flux density, after allowing for lensing magnification, of about 1 {mu}Jy, intrinsically probably the faintest radio source yet detected. This reinforces the utility of gravitational lensing in potentially allowing us to study nJy-level sources before the advent of the Square Kilometre Array. In an optical observation taken three months after the radio observation, image C is the brightest image, whereas the radio map shows flux density ratios consistent with previous optical observations. Future observations separated by a time delay will give the intrinsic flux ratios of the images in this source.

  16. Global structure and dynamics of large-scale fluctuations in the solar wind: Voyager 2 observations during 2005 and 2006

    NASA Astrophysics Data System (ADS)

    Burlaga, L. F.; Ness, N. F.; Acũna, M. H.; Wang, Y.-M.; Sheeley, N. R.; Wang, C.; Richardson, J. D.

    2008-02-01

    The Voyager 2 (V2) observations of daily averages of the solar wind during 2005 and 2006 from 75.3 AU to 81.6 AU between ~25.7°S and 27.1°S show both a step-like trend in the speed V(t) and ``large-scale fluctuations'' of the magnetic field strength B, speed V, density N and temperature T. The distribution functions of B, N, and NV2 observed by V2 are lognormal and that of V is approximately Gaussian. We introduce a method for specifying the boundary conditions at all latitudes (except near the poles) on a Sun-centered surface of radius of 1 AU, based on solar magnetic field observations. This paper uses only the boundary conditions at the latitude of V2 and a 1-D time-dependent MHD model to calculate the radial evolution of the large-scale fluctuations of B(t), V(t) and N(t) at distances between 1 and 90 AU. This model explains the V2 observations of a lognormal distribution of B and the Gaussian distribution of V, but not the observed lognormal distributions of N and NV2. The lognormal distribution of B observed by V2 was produced primarily by dynamical processes beyond 1 AU.

  17. Circular on family planning, 1988.

    PubMed

    1988-01-01

    This Hubei, China, Circular, issued near the end of 1988, provides the following: "The population growth situation in our country is grim. Since 1986, the natural population growth rate has risen continuously. To draw the prompt attention of the whole party and the entire people to the issue of our population, all localities must seriously unfold the activities of publicizing family planning (FP) this winter and next spring, in coordination with education in current affairs. It is necessary to publicize FP in an all-around way and with accuracy, and the activities of publicizing must be carried out effectively in a solid and deep-going way. In the rural areas, stress must be placed on areas where FP work is not carried out well and where there is a prevailing tendency toward early marriage, early child-bearing, and extra-budgetary births. In cities, publicity and education must be conducted especially among the transient population, individual households, and jobless households. During the period of publicity, large-scale street-corner publicity activities must be carried out in cities and towns so as to create strong public opinion and to combine the endeavor to publicize current affairs and policies with the effort to popularize knowledge about contraception and birth-control, to execute measures of contraception and birth control, and to establish FP associations in the countryside."

  18. Observations of the Large Magellanic Cloud in high-energy gamma rays

    NASA Technical Reports Server (NTRS)

    Sreekumar, P.; Bertsch, D. L.; Dingus, B. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.; Mattox, J. R.

    1992-01-01

    The LMC provides a valuable site to study gamma-ray production, intensity, and distribution in an external galaxy. Using 4 weeks of data from the Energetic Gamma Ray Experiment Telescope (EGRET) aboard the Compton Gamma Ray Observatory, high-energy gamma-ray emission was detected for the first time from the LMC region. These gamma rays are believed to be produced primarily through the interaction of cosmic rays with interstellar matter. Hence, combined with a knowledge of the interstellar matter distribution, they can provide a direct measure of the cosmic-ray density in an external galaxy. The results obtained from EGRET observations indicate that the level of cosmic rays in the LMC is comparable to that in our Galaxy. The integrated flux above 100 MeV is (1.9 +/- 0.4) x 10 exp -7 photons/(sq cm s). The measured flux suggests a cosmic-ray density level consistent with that expected from a quasi-stable equilibrium model. This is the first detection of a normal galaxy outside the Milky Way in high-energy gamma rays.

  19. Observed forest sensitivity to climate implies large changes in 21st century North American forest growth.

    PubMed

    Charney, Noah D; Babst, Flurin; Poulter, Benjamin; Record, Sydne; Trouet, Valerie M; Frank, David; Enquist, Brian J; Evans, Margaret E K

    2016-09-01

    Predicting long-term trends in forest growth requires accurate characterisation of how the relationship between forest productivity and climatic stress varies across climatic regimes. Using a network of over two million tree-ring observations spanning North America and a space-for-time substitution methodology, we forecast climate impacts on future forest growth. We explored differing scenarios of increased water-use efficiency (WUE) due to CO2 -fertilisation, which we simulated as increased effective precipitation. In our forecasts: (1) climate change negatively impacted forest growth rates in the interior west and positively impacted forest growth along the western, southeastern and northeastern coasts; (2) shifting climate sensitivities offset positive effects of warming on high-latitude forests, leaving no evidence for continued 'boreal greening'; and (3) it took a 72% WUE enhancement to compensate for continentally averaged growth declines under RCP 8.5. Our results highlight the importance of locally adapted forest management strategies to handle regional differences in growth responses to climate change.

  20. Observation of energetic electron confinement in a largely stochastic reversed-field pinch plasma

    NASA Astrophysics Data System (ADS)

    Clayton, D. J.; Chapman, B. E.; O'Connell, R.; Almagri, A. F.; Burke, D. R.; Forest, C. B.; Goetz, J. A.; Kaufman, M. C.; Bonomo, F.; Franz, P.; Gobbin, M.; Piovesan, P.

    2010-01-01

    Runaway electrons with energies >100 keV are observed with the appearance of an m =1 magnetic island in the core of otherwise stochastic Madison Symmetric Torus [Dexter et al., Fusion Technol. 19, 131 (1991)] reversed-field-pinch plasmas. The island is associated with the innermost resonant tearing mode, which is usually the largest in the m =1 spectrum. The island appears over a range of mode spectra, from those with a weakly dominant mode to those, referred to as quasi single helicity, with a strongly dominant mode. In a stochastic field, the rate of electron loss increases with electron parallel velocity. Hence, high-energy electrons imply a region of reduced stochasticity. The global energy confinement time is about the same as in plasmas without high-energy electrons or an island in the core. Hence, the region of reduced stochasticity must be localized. Within a numerical reconstruction of the magnetic field topology, high-energy electrons are substantially better confined inside the island, relative to the external region. Therefore, it is deduced that the island provides a region of reduced stochasticity and that the high-energy electrons are generated and well confined within this region.

  1. Circular Scan Streak Tube Development

    NASA Technical Reports Server (NTRS)

    Nevin, S.

    1980-01-01

    A streak tube having circular scan was designed, built and tested. Continuous circular scan, easily derived from out of phase sine waves applied to the conventional deflection plates, permits the timing of pulses traveling long baselines. At the tube's output a circular array of 720 elements is scanned to provide 30 to 40 picosecond resolution. Initial difficulties with electron bombarded silicon arrays were circumvented by using microchannel plates within the streak tube to provide the needed electronic amplification and digital sensitivity and coupling the 720 element arrays to the electron beam by means of a phosphor on a fiber optics. Two ceramic body tubes with S-20 photocathodes were tested and delivered.

  2. An Enhanced Method for Scheduling Observations of Large Sky Error Regions for Finding Optical Counterparts to Transients

    NASA Astrophysics Data System (ADS)

    Rana, Javed; Singhal, Akshat; Gadre, Bhooshan; Bhalerao, Varun; Bose, Sukanta

    2017-04-01

    The discovery and subsequent study of optical counterparts to transient sources is crucial for their complete astrophysical understanding. Various gamma-ray burst (GRB) detectors, and more notably the ground-based gravitational wave detectors, typically have large uncertainties in the sky positions of detected sources. Searching these large sky regions spanning hundreds of square degrees is a formidable challenge for most ground-based optical telescopes, which can usually image less than tens of square degrees of the sky in a single night. We present algorithms for better scheduling of such follow-up observations in order to maximize the probability of imaging the optical counterpart, based on the all-sky probability distribution of the source position. We incorporate realistic observing constraints such as the diurnal cycle, telescope pointing limitations, available observing time, and the rising/setting of the target at the observatory’s location. We use simulations to demonstrate that our proposed algorithms outperform the default greedy observing schedule used by many observatories. Our algorithms are applicable for follow-up of other transient sources with large positional uncertainties, such as Fermi-detected GRBs, and can easily be adapted for scheduling radio or space-based X-ray follow-up.

  3. Do recent observations of very large electromagnetic dissociation cross sections signify a transition towards non-perturbative QED?

    NASA Technical Reports Server (NTRS)

    Norbury, John W.

    1992-01-01

    The very large electromagnetic dissociation (EMD) cross section recently observed by Hill, Wohn, Schwellenbach, and Smith do not agree with Weizsacker-Williams (WW) theory or any simple modification thereof. Calculations are presented for the reaction probabilities for this experiment and the entire single and double nucleon removal EMD data set. It is found that for those few reactions where theory and experiment disagree, the probabilities are exceptionally large. This indicates that WW theory is not valid for these reactions and that one must consider higher order corrections and perhaps even a non-perturbative approach to quantum electrodynamics (QED).

  4. Fermi Large Area Telescope Observations of the Supernova Remnant GS.7-0.1

    NASA Technical Reports Server (NTRS)

    Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Ferrara, E. C.; Harding, A. K.; Hays, E.; Moiseev, A. A.; Troja, E.

    2011-01-01

    We present a detailed analysis of the GeV gamma-ray emission toward the supernova remnant (SNR) G8.7-0.1 with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. An investigation of the relationship among G8.7-0.l and the TeV unidentified source HESS J1804-216 provides us with an important clue on diffusion process of cosmic rays if particle acceleration operates in the SNR. The GeV gamma-ray emission is extended with most of the emission in positional coincidence with the SNR G8.7-0.l and a lesser part located outside the western boundary of G8.7-0.l. The region of the gamma-ray emission overlaps spatially-connected molecular clouds, implying a physical connection for the gamma-ray structure. The total gamma-ray spectrum measured with LAT from 200 MeV-100 GeV can be described by a broken power-law function with a break of 2.4 +/- 0.6 (stat) +/- 1.2 (sys) GeV, and photon indices of 2.10 +/- 0.06 (stat) +/- 0.10 (sys) below the break and 2.70 +/- 0.12 (stat) +/- 0.l4 (sys) above the break. Given the spatial association among the gamma rays, the radio emission of G8.7-0.1, and the molecular clouds, the decay of 1IoS produced by particles accelerated in the SNR and hitting the molecular clouds naturally explains the GeV gamma-ray spectrum. We also find that the GeV morphology is not well represented by the TeV emission from HESS J1804-216 and that the spectrum in the GeV band is not consistent with the extrapolation of the TeV gamma-ray spectrum. The spectral index of the TeV emission is consistent with the particle spectral index predicted by a theory that assumes energy-dependent diffusion of particles accelerated in an SNR. We discuss the possibility that the TeV spectrum originates from the interaction of particles accelerated in G8.7-0.1 with molecular clouds, and we constrain the diffusion coefficient of the particles.

  5. Fermi Large Area Telescope Observations of the Supernova Remnant GS.7-0.1

    NASA Technical Reports Server (NTRS)

    Ferrara, E. C.; Hays, E.; Troja, E.; Moiseev, A. A.

    2012-01-01

    We present a detailed analysis of the GeV gamma-ray emission toward the supernova remnant (SNR) G8.7-0.1 with the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope. An investigation of the relationship among G8.7-0.1 and the TeV unidentified source HESS J1804-216 provides us with an important clue on diffusion process of cosmic rays if particle acceleration operates in the SNR. The GeV gamma-ray emission is extended with most of the emission in positional coincidence with the SNR G8.7-0.1 and a lesser part located outside the western boundary of G8.7-0.1. The region of the gamma-ray emission overlaps spatially-connected molecular clouds, implying a physical connection for the gamma-ray structure. The total gamma-ray spectrum measured with LAT from 200 MeV-100 GeV can be described by a broken power-law function with a break of 2.4 +/- 0.6 (stat) +/- 1.2 (sys) GeV, and photon indices of2.10 +/- 0.06 (stat) +/- 0.10 (sys) below the break and 2.70 +/- 0.12 (stat) +/- 0.14 (sys) above the break. Given the spatial association among the gamma rays, the radio emission ofG8.7-0.1, and the molecular clouds, the decay of pions produced by particles accelerated in the SNR and hitting the molecular clouds naturally explains the GeV gamma-ray spectrum. We also find that the GeV morphology is not well represented by the TeV emission from HESS Jl804-2l6 and that the spectrum in the Ge V band is not consistent with the extrapolation of the TeV gamma-ray spectrum. The spectral index of the TeV emission is consistent with the particle spectral index predicted by a theory that assumes energy-dependent diffusion of particles accelerated in an SNR. We discuss the possibility that the TeV-spectrum originates from the interaction of particles accelerated in G8.7-0.l with molecular clouds, and we constrain the diffusion coefficient of the particles.

  6. Fermi Large Area Telescope Observations of the Supernova Remnant G8.7-0.1

    SciTech Connect

    Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R.D.; Bloom, E.D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G.A.; Cameron, R.A.; Caraveo, P.A.; /more authors..

    2012-09-14

    We present a detailed analysis of the GeV gamma-ray emission toward the supernova remnant (SNR) G8.7-0.1 with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. An investigation of the relationship between G8.7-0.1 and the TeV unidentified source HESS J1804-216 provides us with an important clue on diffusion process of cosmic rays if particle acceleration operates in the SNR. The GeV gamma-ray emission is extended with most of the emission in positional coincidence with the SNR G8.7-0.1 and a lesser part located outside the western boundary of G8.7-0.1. The region of the gamma-ray emission overlaps spatially connected molecular clouds, implying a physical connection for the gamma-ray structure. The total gamma-ray spectrum measured with LAT from 200 MeV-100 GeV can be described by a broken power-law function with a break of 2.4 {+-} 0.6 (stat) {+-} 1.2 (sys) GeV, and photon indices of 2.10 {+-} 0.06 (stat) {+-} 0.10 (sys) below the break and 2.70 {+-} 0.12 (stat) {+-} 0.14 (sys) above the break. Given the spatial association among the gamma rays, the radio emission of G8.7-0.1, and the molecular clouds, the decay of p0s produced by particles accelerated in the SNR and hitting the molecular clouds naturally explains the GeV gamma-ray spectrum. We also find that the GeV morphology is not well represented by the TeV emission from HESS J1804-216 and that the spectrum in the GeV band is not consistent with the extrapolation of the TeV gamma-ray spectrum. The spectral index of the TeV emission is consistent with the particle spectral index predicted by a theory that assumes energy-dependent diffusion of particles accelerated in an SNR. We discuss the possibility that the TeV spectrum originates from the interaction of particles accelerated in G8.7-0.1 with molecular clouds, and we constrain the diffusion coefficient of the particles.

  7. Fermi Large Area Telescope Observations of Markarian 421: The Missing Piece of its Spectral Energy Distribution

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Cannon, A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Escande, L.; Favuzzi, C.; Fegan, S. J.; Finke, J.; Focke, W. B.; Fortin, P.; Frailis, M.; Fuhrmann, L.; Fukazawa, Y.; Fukuyama, T.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Georganopoulos, M.; Germani, S.; Giebels, B.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Guiriec, S.; Hadasch, D.; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kadler, M.; Kamae, T.; Katagiri, H.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Max-Moerbeck, W.; Mazziotta, M. N.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-Godo, M.; Nishino, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paneque, D.; Panetta, J. H.; Parent, D.; Pavlidou, V.; Pearson, T. J.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Readhead, A.; Reimer, A.; Reimer, O.; Reyes, L. C.; Richards, J. L.; Ritz, S.; Roth, M.; Sadrozinski, H. F.-W.; Sanchez, D.; Sander, A.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Stawarz, Ł.; Stevenson, M.; Strickman, M. S.; Suson, D. J.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Troja, E.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Wehrle, A. E.; Winer, B. L.; Wood, K. S.; Yang, Z.; Yatsu, Y.; Ylinen, T.; Zensus, J. A.; Ziegler, M.; Fermi LAT Collaboration; Aleksić, J.; Antonelli, L. A.; Antoranz, P.; Backes, M.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Berdyugin, A.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Boller, A.; Bonnoli, G.; Bordas, P.; Borla Tridon, D.; Bosch-Ramon, V.; Bose, D.; Braun, I.; Bretz, T.; Camara, M.; Carmona, E.; Carosi, A.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Dazzi, F.; de Angelis, A.; De Cea del Pozo, E.; Delgado Mendez, C.; De Lotto, B.; De Maria, M.; De Sabata, F.; Diago Ortega, A.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Elsaesser, D.; Ferenc, D.; Fonseca, M. V.; Font, L.; García López, R. J.; Garczarczyk, M.; Gaug, M.; Giavitto, G.; Godinovi, N.; Hadasch, D.; Herrero, A.; Hildebrand, D.; Höhne-Mönch, D.; Hose, J.; Hrupec, D.; Jogler, T.; Klepser, S.; Krähenbühl, T.; Kranich, D.; Krause, J.; La Barbera, A.; Leonardo, E.; Lindfors, E.; Lombardi, S.; López, M.; Lorenz, E.; Majumdar, P.; Makariev, E.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Miyamoto, H.; Moldón, J.; Moralejo, A.; Nieto, D.; Nilsson, K.; Orito, R.; Oya, I.; Paoletti, R.; Paredes, J. M.; Partini, S.; Pasanen, M.; Pauss, F.; Pegna, R. G.; Perez-Torres, M. A.; Persic, M.; Peruzzo, J.; Pochon, J.; Prada, F.; Prada Moroni, P. G.; Prandini, E.; Puchades, N.; Puljak, I.; Reichardt, T.; Rhode, W.; Ribó, M.; Rico, J.; Rissi, M.; Rügamer, S.; Saggion, A.; Saito, K.; Saito, T. Y.; Salvati, M.; Sánchez-Conde, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shayduk, M.; Shore, S. N.; Sierpowska-Bartosik, A.; Sillanpää, A.; Sitarek, J.; Sobczynska, D.; Spanier, F.; Spiro, S.; Stamerra, A.; Steinke, B.; Storz, J.; Strah, N.; Struebig, J. C.; Suric, T.; Takalo, L. O.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Vankov, H.; Wagner, R. M.; Weitzel, Q.; Zabalza, V.; Zandanel, F.; Zanin, R.; MAGIC Collaboration; Villata, M.; Raiteri, C.; Aller, H. D.; Aller, M. F.; Chen, W. P.; Jordan, B.; Koptelova, E.; Kurtanidze, O. M.; Lähteenmäki, A.; McBreen, B.; Larionov, V. M.; Lin, C. S.; Nikolashvili, M. G.; Reinthal, R.; Angelakis, E.; Capalbi, M.; Carramiñana, A.; Carrasco, L.; Cassaro, P.; Cesarini, A.; Falcone, A.; Gurwell, M. A.; Hovatta, T.; Kovalev, Yu. A.; Kovalev, Y. Y.; Krichbaum, T. P.; Krimm, H. A.; Lister, M. L.; Moody, J. W.; Maccaferri, G.; Mori, Y.; Nestoras, I.; Orlati, A.; Pace, C.; Pagani, C.; Pearson, R.; Perri, M.; Piner, B. G.; Ros, E.; Sadun, A. C.; Sakamoto, T.; Tammi, J.; Zook, A.

    2011-08-01

    We report on the γ-ray activity of the high-synchrotron-peaked BL Lacertae object Markarian 421 (Mrk 421) during the first 1.5 years of Fermi operation, from 2008 August 5 to 2010 March 12. We find that the Large Area Telescope (LAT) γ-ray spectrum above 0.3 GeV can be well described by a power-law function with photon index Γ = 1.78 ± 0.02 and average photon flux F(> 0.3 GeV) = (7.23 ± 0.16) × 10-8 ph cm-2 s-1. Over this time period, the Fermi-LAT spectrum above 0.3 GeV was evaluated on seven-day-long time intervals, showing significant variations in the photon flux (up to a factor ~3 from the minimum to the maximum flux) but mild spectral variations. The variability amplitude at X-ray frequencies measured by RXTE/ASM and Swift/BAT is substantially larger than that in γ-rays measured by Fermi-LAT, and these two energy ranges are not significantly correlated. We also present the first results from the 4.5 month long multifrequency campaign on Mrk 421, which included the VLBA, Swift, RXTE, MAGIC, the F-GAMMA, GASP-WEBT, and other collaborations and instruments that provided excellent temporal and energy coverage of the source throughout the entire campaign (2009 January 19 to 2009 June 1). During this campaign, Mrk 421 showed a low activity at all wavebands. The extensive multi-instrument (radio to TeV) data set provides an unprecedented, complete look at the quiescent spectral energy distribution (SED) for this source. The broadband SED was reproduced with a leptonic (one-zone synchrotron self-Compton) and a hadronic model (synchrotron proton blazar). Both frameworks are able to describe the average SED reasonably well, implying comparable jet powers but very different characteristics for the blazar emission site.

  8. High-Throughput Sequencing Reveals Circular Substrates for an Archaeal RNA ligase.

    PubMed

    Becker, Hubert F; Heliou, Alice; Djaout, Kamel; Lestini, Roxane; Regnier, Mireille; Myllykallio, Hannu

    2017-03-09

    It is only recently that the abundant presence of circular RNAs (circRNAs) in all kingdoms of Life, including the hyperthermophilic archaeon Pyrococcus abyssi, has emerged. This led us to investigate the physiological significance of a previously observed weak intramolecular ligation activity of Pab1020 RNA ligase. Here we demonstrate that this enzyme, despite sharing significant sequence similarity with DNA ligases, is indeed an RNA-specific polynucleotide ligase efficiently acting on physiologically significant substrates. Using a combination of RNA immunoprecipitation assays and RNA-seq, our genome-wide studies revealed 133 individual circRNA loci in P. abyssi. The large majority of these loci interacted with Pab1020 in cells and circularization of selected C/D Box and 5S rRNA transcripts was confirmed biochemically. Altogether these studies revealed that Pab1020 is required for RNA circularization. Our results further suggest the functional speciation of an ancestral NTase domain and/or DNA ligase towards RNA ligase activity and prompt for further characterization of the widespread functions of circular RNAs in prokaryotes. Detailed insight into the cellular substrates of Pab1020 may facilitate the development of new biotechnological applications e.g. in ligation of preadenylated adaptors to RNA molecules.

  9. Estimating SO2 emissions from a large point source using 10 year OMI SO2 observations: Afsin Elbistan Power Plant

    NASA Astrophysics Data System (ADS)

    Kaynak Tezel, Burcak; Firatli, Ertug

    2016-04-01

    SO2 pollution has still been a problem for parts of Turkey, especially regions with large scale coal power plants. In this study, 10 year Ozone Monitoring Instrument (OMI) SO2 observations are used for estimating SO2 emissions from large point sources in Turkey. We aim to estimate SO2 emissions from coal power plants where no online monitoring is available and improve the emissions given in current emission inventories with these top-down estimates. High-resolution yearly averaged maps are created on a domain over large point sources by oversampling SO2 columns for each grid for the years 2005-2014. This method reduced the noise and resulted in a better signal from large point sources and it was used for coal power plants in U.S and India, previously. The SO2 signal over selected power plants are observed with this method, and the spatiotemporal changes of SO2 signal are analyzed. With the assumption that OMI SO2 observations are correlating with emissions, long-term OMI SO2 observation averages can be used to estimate emission levels of significant point sources. Two-dimensional Gaussian function is used for explaining the relationships between OMI SO2 observations and emissions. Afsin Elbistan Power Plant, which is the largest capacity coal power plant in Turkey, is investigated in detail as a case study. The satellite scans within 50 km of the power plant are selected and averaged over a 2 x 2 km2 gridded domain by smoothing method for 2005-2014. The yearly averages of OMI SO2 are calculated to investigate the magnitude and the impact area of the SO2 emissions of the power plant. A significant increase in OMI SO2 observations over Afsin Elbistan from 2005 to 2009 was observed (over 2 times) possibly due to the capacity increase from 1715 to 2795 MW in 2006. Comparison between the yearly gross electricity production of the plant and OMI SO2 observations indicated consistency until 2009, but OMI SO2 observations indicated a rapid increase while gross electricity

  10. The Energy Budget of GRBs Based on a Large Sample of Prompt and Afterglow Observations

    NASA Astrophysics Data System (ADS)

    Wygoda, N.; Guetta, D.; Mandich, M. A.; Waxman, E.

    2016-06-01

    We compare the isotropic equivalent 15-2000 keV γ-ray energy, E γ , emitted by a sample of 91 swift Gamma-Ray Bursts with known redshifts, with the isotropic equivalent fireball energy, E fb, as estimated within the fireball model framework from X-ray afterglow observations of these bursts. The uncertainty in E γ , which spans the range of ˜1051 to ˜1053.5 erg, is ≈25% on average, due mainly to the extrapolation from the BAT detector band to the 15-2000 keV band. The uncertainty in E fb is approximately a factor of 2, due mainly to the X-ray measurements’ scatter. We find E γ and E fb to be tightly correlated. The average(std) of {η }γ 11 {hr}\\equiv {{log}}10({E}γ /(3{\\varepsilon }{{e}}{E}{{fb}}11 {hr})) are -0.34(0.60), and the upper limit on the intrinsic spread of η γ is approximately 0.5 ({\\varepsilon }{{e}} is the fraction of energy carried by electrons and {E}{{fb}}x {hr} is inferred from the X-ray flux at x hours). {E}{{fb}}3 {hr} and {E}{{fb}}11 {hr} are similar, with an average(std) of {{log}}10({E}{{fb}}3 {hr}/{E}{{fb}}11 {hr}) of 0.04(0.28). The small variance of η γ implies that burst-to-burst variations in {\\varepsilon }{{e}} and in the efficiency of fireball energy conversion to γ-rays are small, and suggests that both are of order unity. The small variance of η γ and the similarity of {E}{{fb}}3 {hr} and {E}{{fb}}11 {hr} further imply that deviations from a simple fireball model description, if present, are small. This puts stringent constraints on models incorporating such modifications (due e.g., to radiative losses, energy injection, off-axis viewing).

  11. SWIFT ULTRAVIOLET OBSERVATIONS OF SUPERNOVA 2014J IN M82: LARGE EXTINCTION FROM INTERSTELLAR DUST

    SciTech Connect

    Brown, Peter J.; Smitka, Michael T.; Wang, Lifan; Krisciunas, Kevin; Breeveld, Alice; Kuin, N. Paul; Page, Mat; De Pasquale, Massimiliano; Hartmann, Dieter H.; Milne, Peter A.; Siegel, Michael

    2015-05-20

    We present optical and ultraviolet (UV) photometry and spectra of the very nearby and highly reddened supernova (SN) 2014J in M82 obtained with the Swift Ultra-Violet/Optical Telescope (UVOT). Comparison of the UVOT grism spectra of SN 2014J with Hubble Space Telescope observations of SN2011fe or UVOT grism spectra of SN 2012fr are consistent with an extinction law with a low value of R{sub V} ∼1.4. The high reddening causes the detected photon distribution in the broadband UV filters to have a much longer effective wavelength than for an unreddened SN. The light curve evolution is consistent with this shift and does not show a flattening due to photons being scattered back into the line of sight (LOS). The light curve shapes and color evolution are inconsistent with a contribution scattered into the LOS by circumstellar dust. We conclude that most or all of the high reddening must come from interstellar dust. We show that even for a single dust composition, there is not a unique reddening law caused by circumstellar scattering. Rather, when considering scattering from a time-variable source, we confirm earlier studies that the reddening law is a function of the dust geometry, column density, and epoch. We also show how an assumed geometry of dust as a foreground sheet in mixed stellar/dust systems will lead to a higher inferred R{sub V}. Rather than assuming the dust around SNe is peculiar, SNe may be useful probes of the interstellar reddening laws in other galaxies.

  12. Strong New Evidence for Oscillation of the Cosmological Scale Factor Observed in the Large Scale Structure

    NASA Astrophysics Data System (ADS)

    Ringermacher, Harry I.; Mead, Lawrence R.

    2017-01-01

    We have analyzed SDSSIII-BOSS, DR9 galaxy number count data using 2 independent approaches, a relativistic expanding space model based on work by Ostriker and direct Fourier analysis, and found incontrovertible evidence for a scale factor oscillation at 7 Hubble-Hertz (HHz) in both methods, where we define 1 HHz as 1 cycle over 1 Hubble-time. The number count of galaxies on these scales should be relatively smooth. However, a DR9 plot of galaxy number count per 0.01 redshift bin as a function of redshift shows significant bumps to redshift 0.5. We take the SDSSIII data (about ¼ of the sky) to be a fair representation of the entire sky when using number count. Our model fits essentially all bumps at a 99.8% R-squared goodness level if and only if the 7 HHz oscillation ( plus 2nd and 3rd harmonics at 14 HHz and 21 HHz) is included. These are the same frequencies observed by us in AJ 149, 137 (2015) using SNe data. Since the SDSSIII data set only goes to redshift 0.8, only one cycle of oscillation is included compared to 2-3 in our earlier work. Thus a Fourier analysis performed on the SDSS redshift data converted to equal-time binning leaves a broadened spectrum over the range where harmonics would normally reside but nevertheless peaked at 7 HHz. A scalar field model presented in the AJ paper describes the oscillation and enters the Friedmann equations by replacing the LCDM dark matter density parameter with the scalar field density. Thus, LCDM dark matter is the median of the wave which appears to act like a fluid with a changing equation-of-state. The oscillation may be a longitudinal gravitational wave originating with the Big Bang and requiring a massive graviton. 7 HHz is consistent with a graviton mass of 10^ -32 eV.

  13. Magnetospheric Multiscale observations of large-amplitude, parallel, electrostatic waves associated with magnetic reconnection at the magnetopause

    NASA Astrophysics Data System (ADS)

    Ergun, R. E.; Holmes, J. C.; Goodrich, K. A.; Wilder, F. D.; Stawarz, J. E.; Eriksson, S.; Newman, D. L.; Schwartz, S. J.; Goldman, M. V.; Sturner, A. P.; Malaspina, D. M.; Usanova, M. E.; Torbert, R. B.; Argall, M.; Lindqvist, P.-A.; Khotyaintsev, Y.; Burch, J. L.; Strangeway, R. J.; Russell, C. T.; Pollock, C. J.; Giles, B. L.; Dorelli, J. J. C.; Avanov, L.; Hesse, M.; Chen, L. J.; Lavraud, B.; Le Contel, O.; Retino, A.; Phan, T. D.; Eastwood, J. P.; Oieroset, M.; Drake, J.; Shay, M. A.; Cassak, P. A.; Nakamura, R.; Zhou, M.; Ashour-Abdalla, M.; André, M.

    2016-06-01

    We report observations from the Magnetospheric Multiscale satellites of large-amplitude, parallel, electrostatic waves associated with magnetic reconnection at the Earth's magnetopause. The observed waves have parallel electric fields (E||) with amplitudes on the order of 100 mV/m and display nonlinear characteristics that suggest a possible net E||. These waves are observed within the ion diffusion region and adjacent to (within several electron skin depths) the electron diffusion region. They are in or near the magnetosphere side current layer. Simulation results support that the strong electrostatic linear and nonlinear wave activities appear to be driven by a two stream instability, which is a consequence of mixing cold (<10 eV) plasma in the magnetosphere with warm (~100 eV) plasma from the magnetosheath on a freshly reconnected magnetic field line. The frequent observation of these waves suggests that cold plasma is often present near the magnetopause.

  14. Confounding in observational studies based on large health care databases: problems and potential solutions - a primer for the clinician.

    PubMed

    Nørgaard, Mette; Ehrenstein, Vera; Vandenbroucke, Jan P

    2017-01-01

    Population-based health care databases are a valuable tool for observational studies as they reflect daily medical practice for large and representative populations. A constant challenge in observational designs is, however, to rule out confounding, and the value of these databases for a given study question accordingly depends on completeness and validity of the information on confounding factors. In this article, we describe the types of potential confounding factors typically lacking in large health care databases and suggest strategies for confounding control when data on important confounders are unavailable. Using Danish health care databases as examples, we present the use of proxy measures for important confounders and the use of external adjustment. We also briefly discuss the potential value of active comparators, high-dimensional propensity scores, self-controlled designs, pseudorandomization, and the use of positive or negative controls.

  15. Confounding in observational studies based on large health care databases: problems and potential solutions – a primer for the clinician

    PubMed Central

    Nørgaard, Mette; Ehrenstein, Vera; Vandenbroucke, Jan P

    2017-01-01

    Population-based health care databases are a valuable tool for observational studies as they reflect daily medical practice for large and representative populations. A constant challenge in observational designs is, however, to rule out confounding, and the value of these databases for a given study question accordingly depends on completeness and validity of the information on confounding factors. In this article, we describe the types of potential confounding factors typically lacking in large health care databases and suggest strategies for confounding control when data on important confounders are unavailable. Using Danish health care databases as examples, we present the use of proxy measures for important confounders and the use of external adjustment. We also briefly discuss the potential value of active comparators, high-dimensional propensity scores, self-controlled designs, pseudorandomization, and the use of positive or negative controls.

  16. NEAR-INFRARED CIRCULAR POLARIZATION IMAGES OF NGC 6334-V

    SciTech Connect

    Kwon, Jungmi; Tamura, Motohide; Hashimoto, Jun; Kusakabe, Nobuhiko; Kandori, Ryo; Lucas, Phil W.; Hough, James H.; Nakajima, Yasushi; Nagayama, Takahiro; Nagata, Tetsuya

    2013-03-01

    We present results from deep imaging linear and circular polarimetry of the massive star-forming region NGC 6334-V. These observations show high degrees of circular polarization (CP), as much as 22% in the K{sub s} band, in the infrared nebula associated with the outflow. The CP has an asymmetric positive/negative pattern and is very extended ({approx}80'' or 0.65 pc). Both the high CP and its extended size are larger than those seen in the Orion CP region. Three-dimensional Monte Carlo light-scattering models are used to show that the high CP may be produced by scattering from the infrared nebula followed by dichroic extinction by an optically thick foreground cloud containing aligned dust grains. Our results show not only the magnetic field orientation of around young stellar objects, but also the structure of circumstellar matter such as outflow regions and their parent molecular cloud along the line of sight. The detection of the large and extended CP in this source and the Orion nebula may imply the CP origin of the biological homochirality on Earth.

  17. Beam Rounders for Circular Colliders

    SciTech Connect

    A. Burov; S. Nagaitsev; Ya. Derbenev

    2001-07-01

    By means of linear optics, an arbitrary uncoupled beam can be locally transformed into a round (rotation-invariant) state and then back. This provides an efficient way to round beams in the interaction region of circular colliders.

  18. Beam rounders for circular colliders

    SciTech Connect

    A. Burov and S. Nagaitsev

    2002-12-10

    By means of linear optics, an arbitrary uncoupled beam can be locally transformed into a round (rotation-invariant) state and then back. This provides an efficient way to round beams in the interaction region of circular colliders.

  19. Beach vortices near circular topography

    NASA Astrophysics Data System (ADS)

    Hinds, A. K.; Johnson, E. R.; McDonald, N. R.

    2016-10-01

    Finite-area monopolar vortices which propagate around topography without change in shape are computed for circular seamounts and wells including the limiting cases of each: islands and infinitely deep wells. The time-dependent behaviour of vortex pairs propagating toward circular topography is also examined. Trajectories of point-vortex pairs exterior to the topography are found and compared to trajectories of vortex patches computed using contour dynamics.

  20. Observation

    ERIC Educational Resources Information Center

    Helfrich, Shannon

    2016-01-01

    Helfrich addresses two perspectives from which to think about observation in the classroom: that of the teacher observing her classroom, her group, and its needs, and that of the outside observer coming into the classroom. Offering advice from her own experience, she encourages and defends both. Do not be afraid of the disruption of outside…

  1. Observations

    ERIC Educational Resources Information Center

    Joosten, Albert Max

    2016-01-01

    Joosten begins his article by telling us that love and knowledge together are the foundation for our work with children. This combination is at the heart of our observation. With this as the foundation, he goes on to offer practical advice to aid our practice of observation. He offers a "List of Objects of Observation" to help guide our…

  2. Observations of a High-Latitude Stable Electron Auroral Emission at Approximately 16 MLT During a Large Substorm

    NASA Technical Reports Server (NTRS)

    Cattell, C.; Dombeck, J.; Preiwisch, A.; Thaller, S.; Vo, P.; Wilson, L. B., III; Wygant, J.; Mende, S. B.; Frey, H. U.; Ilie, R.; Lu, G.

    2011-01-01

    During an interval when the interplanetary magnetic field was large and primarily duskward and southward, a stable region of auroral emission was observed on 17 August 2001 by IMAGE at 16 magnetic local time, poleward of the main aurora, for 1 h, from before the onset of a large substorm through the recovery phase. In a region where ions showed the energy dispersion expected for the cusp, strong field \\aligned currents and Poynting flux were observed by Polar (at 1.8 RE in the Southern Hemisphere) as it transited field lines mapping to the auroral spot in the Northern Hemisphere. The data are consistent with the hypothesis that the long \\lasting electron auroral spot maps to the magnetopause region where reconnection was occurring. Under the assumption of conjugacy between the Northern and Southern hemispheres on these field lines, the Polar data suggest that the electrons on these field lines were accelerated by Alfven waves and/or a quasi \\static electric field, primarily at altitudes below a few RE since the in situ Poynting flux (mapped to 100 km) is comparable to the energy flux of the emission while the mapped in situ electron energy flux is much smaller. This event provides the first example of an emission due to electrons accelerated at low altitudes at the foot point of a region of quasi \\steady dayside reconnection. Cluster data in the magnetotail indicate that the Poynting flux from the reconnection region during this substorm is large enough to account for the observed nightside aurora.

  3. Diffuse Optical Intracluster Light as a Measure of Stellar Tidal Stripping: The Cluster CL0024+17 at z ~ 0.4 Observed at the Large Binocular Telescope

    NASA Astrophysics Data System (ADS)

    Giallongo, E.; Menci, N.; Grazian, A.; Gallozzi, S.; Castellano, M.; Fiore, F.; Fontana, A.; Pentericci, L.; Boutsia, K.; Paris, D.; Speziali, R.; Testa, V.

    2014-01-01

    We have evaluated the diffuse intracluster light (ICL) in the central core of the galaxy cluster CL0024+17 at z ~ 0.4 observed with the prime focus camera (Large Binocular Camera) at the Large Binocular Telescope. The measure required an accurate removal of the galaxies' light within ~200 kpc from the center. The residual background intensity has then been integrated in circular apertures to derive the average ICL intensity profile. The latter shows an approximate exponential decline as expected from theoretical cold dark matter models where the ICL is due to the integrated contribution of light from stars that are tidally stripped from the halo of their host galaxies due to encounters with other galaxies in the cluster cold dark matter (CDM) potential. The radial profile of the ICL over the galaxies intensity ratio (ICL fraction) is increasing with decreasing radius, but near the cluster center it starts to bend and then decreases where the overlap of the halos of the brightest cluster galaxies becomes dominant. Theoretical expectations in a simplified CDM scenario show that the ICL fraction profile can be estimated from the stripped over galaxy stellar mass ratio in the cluster. It is possible to show that the latter quantity is almost independent of the properties of the individual host galaxies but mainly depends on the average cluster properties. The predicted ICL fraction profile is thus very sensitive to the assumed CDM profile, total mass, and concentration parameter of the cluster. Adopting values very similar to those derived from the most recent lensing analysis in CL0024+17, we find a good agreement with the observed ICL fraction profile. The galaxy counts in the cluster core have then been compared with that derived from composite cluster samples in larger volumes, up to the clusters virial radius. The galaxy counts in the CL0024+17 core appear flatter and the amount of bending with respect to the average cluster galaxy counts imply a loss of total

  4. Monitoring observations of the interaction between Sgr A* and G2 with the Karl G. Jansky Very Large Array

    NASA Astrophysics Data System (ADS)

    Sjouwerman, Loránt O.; Chandler, Claire J.

    2014-05-01

    We report on an ongoing community service observing program to follow the expected encounter of the G2 cloud with the black hole Sgr A* in 2013. The NRAO Karl G. Jansky Very Large Array (VLA) has been observing the Sgr A region since 2012 October on roughly a bi-monthly interval, each for two hours, cycling through eight observing bands at their default continuum frequencies, using 2 GHz of bandwidth. The data from the monitoring program are publicly available through the NRAO data archive immediately after observing has completed, and the flux densities are published by NRAO staff as soon as the data are reduced. The cumulative results of the monitoring effort are posted on the service observing web page observing" xlink:type="simple">https://science.nrao.edu/science/service-observing and so far do not indicate a significant brightening of the emission from the direction of Sgr A* over the period 2012 October to 2013 September, within the calibration uncertainties.

  5. Photoelectron circular dichroism in different ionization regimes

    NASA Astrophysics Data System (ADS)

    Wollenhaupt, Matthias

    2016-12-01

    Photoelectron circular dichroism (PECD) describes an asymmetry in the photoelectron angular distribution (PAD) from photoionization of randomly oriented enantiomers with circularly polarized light. Baulieu et al present a comprehensive set of measured PADs from multiphoton ionization of limonene and fenchone in different ionization regimes (multiphoton and tunneling) and analyze the resulting PECD (Baulieu et al 2016 New J. Phys. 18 102002). From their observations the authors conclude that the PECD is universal in the sense that the molecular chirality is encoded in the PAD independent of the ionization regime. The analysis is supplemented by a classical model based on electron scattering in a chiral potential. The paper presents beautiful data and is an important step towards a more complete physical picture of PECD. The results and their interpretation stimulate the ongoing vivid debate on the role of resonances in multiphoton PECD.

  6. Correlated particle and magnetic field observations of a large-scale magnetic loop structure behind an interplanetary shock

    NASA Technical Reports Server (NTRS)

    Sanderson, T. R.; Marsden, R. G.; Reinhard, R.; Wenzel, K.-P.; Smith, E. J.

    1983-01-01

    From a survey of observations on ISEE-3, an example of correlated particle and magnetic field observations of a large-scale magnetic loop structure is presented. Bidirectional proton fluxes were observed for a period of 40 hours in the energy range 35-1600 keV approximately 12 hours after the passage of the interplanetary shock of December 11, 1980, and directly after the passage of a discontinuity. For each of the eight logarithmically spaced energy channels, a three-dimensional anisotropy analysis reveals streaming along both directions of the magnetic field. The magnetic field rotated slowly but steadily through approximately 180 deg during this same 40-hour period; this is consistent with the existence of a large-scale loop with extent greater than 0.5 AU. The observations suggest that the particles are being injected into the loop sunward of the spacecraft; they appear as bidirectional fluxes in the outermost regions of the loop arising from a combination of focusing and near scatter-free transport.

  7. Observation of the activity of selected Oort Cloud comets with perihelia at large distances from the Sun

    NASA Astrophysics Data System (ADS)

    Kulyk, Iryna; Rousselot, Philippe; Korsun, Pavlo

    2016-10-01

    Many comets exhibit considerable level of activity at large distances from the Sun, where sublimation of crystalline water ice cannot account for observable comae. Different patterns of physical activity already observed at large heliocentric distances may be related to the primordial differences in the composition of comet nuclei. Therefore, monitoring of physical activity in the wide range of heliocentric distances can potentially contribute to understanding of internal structure of comet-like bodies. We have observed ten long periodic comets with orbital perihelia lying beyond the "water ice sublimation zone" to quantify the level of physical activity in the wide range of heliocentric distances. Pre-perihelion observations were made when targets moved between 16.7 and 6.5 au from the Sun; post perihelion activity was monitored between 5.2 and 10.6 au. The bulk of the data were gathered with the 2-m Robotic Liverpool Telescope (Observatorio del Roque de Los Muchachos, La Palma, Spain). Some targets were observed with the 2-m RC Telescope located at Peak Terskol Observatory and the 6-m Telescope of the Special Astrophysical Observatory (Northern Caucasus, Russia). Since most of recently obtained spectra of distant active objects are continuum dominated, we use B, V, R images to estimate dust production rates, an upper limit on nucleus radii, and color indices of near nucleus region. The comets C/2005 L3 (McNaught) and C/2006 S3 (Boattini), which exhibit the considerable level of activity, have been repeatedly observed. This enables us to infer the heliocentric dependence of dust production rates, perihelion brightness asymmetries, and color variations over the comae caused possibly by small changes in dust particle properties.

  8. Reproducing cloud and boundary layer structure observed in MAGIC campaign using ship-following large-eddy simulations

    NASA Astrophysics Data System (ADS)

    McGibbon, J.; Bretherton, C. S.

    2015-12-01

    The 2012-2013 MAGIC shipborne deployment of the ARM mobile facility sampled a broad range of subtropical marine stratocumulus (Sc), cumulus (Cu), and transition regimes during cruises between Long Beach, CA, and Hololulu, HI. Ship-following large-eddy simulations (LES) of selected cruise legs of 4-5 days are compared with a broad suite of observations of cloud structure and radiative properties taken on the Horizon Spirit ship. This quantitative comparison across a realistic range of conditions assesses the suitability of LES for simulating the sensitivity of such cloud regimes to climate perturbations, and for guiding the development of cloud and boundary layer parameterizations in global climate and weather forecast models. The System for Atmospheric Modeling (SAM) LES is used with a small, doubly-periodic domain and variable vertical resolution, initialized using thermodynamic radiosonde profiles near the start of each cruise leg. Sea-surface temperatures are prescribed from observations, and ECMWF analyses are used to derive time-varying geostrophic wind, ship-relative large-scale advective forcing, and large-scale vertical velocity. ECMWF vertical velocities are adjusted to keep the temperature profile close to radiosonde profiles with a relaxation timescale of 1 day. The ship-measured accumulation-mode aerosol concentration is assumed throughout the boundary layer for nucleation of cloud droplets. The ship-following approach allows efficient comparison of model output with a broad suite of ship-based observations. The simulations cannot be expected to match the observations on timescales less than three hours because of cloud-scale and mesoscale sampling variability. Nevertheless, a preliminary sample of eleven 2D runs of different legs predicts daily mean cloud fraction and surface longwave radiation with negligible systematic bias and correlation coefficients of 0.33 and 0.53, respectively. Full-leg 3D simulations will also be evaluated and presented.

  9. SWAP OBSERVATIONS OF THE LONG-TERM, LARGE-SCALE EVOLUTION OF THE EXTREME-ULTRAVIOLET SOLAR CORONA

    SciTech Connect

    Seaton, Daniel B.; De Groof, Anik; Berghmans, David; Nicula, Bogdan; Shearer, Paul

    2013-11-01

    The Sun Watcher with Active Pixels and Image Processing (SWAP) EUV solar telescope on board the Project for On-Board Autonomy 2 spacecraft has been regularly observing the solar corona in a bandpass near 17.4 nm since 2010 February. With a field of view of 54 × 54 arcmin, SWAP provides the widest-field images of the EUV corona available from the perspective of the Earth. By carefully processing and combining multiple SWAP images, it is possible to produce low-noise composites that reveal the structure of the EUV corona to relatively large heights. A particularly important step in this processing was to remove instrumental stray light from the images by determining and deconvolving SWAP's point-spread function from the observations. In this paper, we use the resulting images to conduct the first-ever study of the evolution of the large-scale structure of the corona observed in the EUV over a three year period that includes the complete rise phase of solar cycle 24. Of particular note is the persistence over many solar rotations of bright, diffuse features composed of open magnetic fields that overlie polar crown filaments and extend to large heights above the solar surface. These features appear to be related to coronal fans, which have previously been observed in white-light coronagraph images and, at low heights, in the EUV. We also discuss the evolution of the corona at different heights above the solar surface and the evolution of the corona over the course of the solar cycle by hemisphere.

  10. Circularly polarized light detection with hot electrons in chiral plasmonic metamaterials

    PubMed Central

    Li, Wei; Coppens, Zachary J.; Besteiro, Lucas V.; Wang, Wenyi; Govorov, Alexander O.; Valentine, Jason

    2015-01-01

    Circularly polarized light is utilized in various optical techniques and devices. However, using conventional optical systems to generate, analyse and detect circularly polarized light involves multiple optical elements, making it challenging to realize miniature and integrated devices. While a number of ultracompact optical elements for manipulating circularly polarized light have recently been demonstrated, the development of an efficient and highly selective circularly polarized light photodetector remains challenging. Here we report on an ultracompact circularly polarized light detector that combines large engineered chirality, realized using chiral plasmonic metamaterials, with hot electron injection. We demonstrate the detector's ability to distinguish between left and right hand circularly polarized light without the use of additional optical elements. Implementation of this photodetector could lead to enhanced security in fibre and free-space communication, as well as emission, imaging and sensing applications for circularly polarized light using a highly integrated photonic platform. PMID:26391292

  11. Large Slow Slip Events and the Nonvolcanic Tremor Observed in the Mexican Subduction Zone are not of the Same Origin

    NASA Astrophysics Data System (ADS)

    Kostoglodov, V.; Husker, A. L.; Shapiro, N. M.; Campillo, M.; Cotte, N.; Clayton, R. W.

    2009-12-01

    There is a growing scientific challenge to understand the origin of recently discovered Slow Slip Events (SSE) and Non-Volcanic Tremor (NVT). SSE and NVT observed now in different subduction zones may be a very important constituent in the seismic cycle of large subduction thrust earthquakes. Large number of observations shows that the SSE is usually associated with an increased NVT activity but it is not clear yet if the NVT and SSE represent the same seismotectonic phenomenon or those are independent expressions of a common origin. Large 2006 SSE in Central Mexico has occurred during the MASE seismic experiment which provided some essential constraints on the problem. We computed a catalog of all NVT recorded with the MASE for 2005-2007, and then using this catalog a space-time distribution of the total NVT radiated energy in 1-2Hz bandwidth was estimated. The energy distribution evidences that the NVT is located within or over the zone of the free slipping subhorizontal interplate contact (at ~ 40 km depth, between 160 and 260 km from the trench). Dislocation models that fit the total surface displacements during the 2006 SSE recorded by GPS stations along the MASE profile, require that almost the entire slow slip was realized on the transition zone of the plate interface, a segment about 70-80 km long located between the seismogenic coupled zone (30-85 km from the trench), and the freely slipping zone. Thus, the SSE and NVT are spatially separated. Four large distinct NVT bursts occurred within one year, during the 2006 SSE, meanwhile there were several comparably large NVT episodes during the “quiet” epochs when no one SSE was detected by GPS. The results of this study clearly show that the SSE and NVT observed in the Mexican subduction zone are the natural phenomena of different origin but the NVT activity is intensified by large SSE. Finally the total estimated seismic energy (assuming that the NVT spectrum is similar to the Brune model) of the NVT

  12. Observation

    ERIC Educational Resources Information Center

    Kripalani, Lakshmi A.

    2016-01-01

    The adult who is inexperienced in the art of observation may, even with the best intentions, react to a child's behavior in a way that hinders instead of helping the child's development. Kripalani outlines the need for training and practice in observation in order to "understand the needs of the children and...to understand how to remove…

  13. 325 MHz VERY LARGE ARRAY OBSERVATIONS OF ULTRACOOL DWARFS TVLM 513-46546 AND 2MASS J0036+1821104

    SciTech Connect

    Jaeger, T. R.; Kassim, N.; Osten, R. A.; Lazio, T. J.; Mutel, R. L.

    2011-12-15

    We present 325 MHz (90 cm wavelength) radio observations of ultracool dwarfs TVLM 513-46546 and 2MASS J0036+1821104 using the Very Large Array (VLA) in 2007 June. Ultracool dwarfs are expected to be undetectable at radio frequencies, yet observations at 8.5 GHz (3.5 cm) and 4.9 GHz (6 cm) have revealed sources with >100 {mu}Jy quiescent radio flux and >1 mJy pulses coincident with stellar rotation. The anomalous emission is likely a combination of gyrosynchrotron and cyclotron maser processes in a long-duration, large-scale magnetic field. Since the characteristic frequency for each process scales directly with the magnetic field magnitude, emission at lower frequencies may be detectable from regions with weaker field strength. We detect no significant radio emission at 325 MHz from TVLM 513-46546 or 2MASS J0036+1821104 over multiple stellar rotations, establishing 2.5{sigma} total flux limits of 795 {mu}Jy and 942 {mu}Jy, respectively. Analysis of an archival VLA 1.4 GHz observation of 2MASS J0036+1821104 from 2005 January also yields a non-detection at the level of <130 {mu}Jy. The combined radio observation history (0.3 GHz to 8.5 GHz) for these sources suggests a continuum emission spectrum for ultracool dwarfs that is either flat or inverted below 2-3 GHz. Further, if the cyclotron maser instability is responsible for the pulsed radio emission observed on some ultracool dwarfs, our low-frequency non-detections suggest that the active region responsible for the high-frequency bursts is confined within two stellar radii and driven by electron beams with energies less than 5 keV.

  14. Observations of Comet P/2003 T12 = 2012 A3 (SOHO) at large phase angle in STEREO-B

    NASA Astrophysics Data System (ADS)

    Hui, Man-To

    2014-11-01

    Comet P/2003 T12 = 2012 A3 (SOHO) was observed by the satellite STEREO-B during the period 2012 January 13-27. During its apparition, it ventured into the highest phase angle ever observed for a comet, and the forward-scattering enhancement in brightness was marked, as large as ˜8.5 mag. Therefore, it provided a precious opportunity to examine the compound Henyey-Greenstein (HG) comet-dust light-scattering model and it also offered valuable polarization data under an unprecedented observing geometry. Our analysis reveals that the compound HG model fits the observations very well until the phase angle exceeds ˜173°, where the brightness surge of the comet was obviously steeper than the prediction by the model. We have found that the reason for the greater steepness cannot be explained by contaminations from the proximal tail. Instead, the model of Mie spheres with radii greater than 1 μm, having a power-law distribution of power index ˜3, matches the observation very well, providing a best-fitting complex refractive index μ = 1.38 + i 0.006. The dust size was found to be consistent with the analysis of the comet's syndyne lines. The debiased polarization of the coma was ˜0 per cent in the phase angle range from 172.9° to 177.6°. No convincing evidence of temporal variation of the polarization was detected.

  15. Observations of Comet P/2003 T12 = 2012 A3 (SOHO) at large phase angle in STEREO-B

    NASA Astrophysics Data System (ADS)

    Hui, M.-T.

    2013-12-01

    Comet P/2003 T12 = 2012 A3 (SOHO) was observed by the satellite STEREO-B during the period 2012 January 13-27. During its apparition, it ventured into the highest phase angle ever observed for a comet, and the forward-scattering enhancement in brightness was marked, as large as ˜8.5 mag. Therefore, it provided a precious opportunity to examine the compound Henyey-Greenstein (HG) comet-dust light-scattering model and it also offered valuable polarization data under an unprecedented observing geometry. Our analysis reveals that the compound HG model fits the observations very well until the phase angle exceeds ˜173°, where the brightness surge of the comet was obviously steeper than the prediction by the model. We have found that the reason for the greater steepness cannot be explained by contaminations from the proximal tail. Instead, the model of Mie spheres with radii greater than 1 μm, having a power-law distribution of power index ˜3, matches the observation very well, providing a best-fitting complex refractive index μ = 1.38 + i 0.006. The dust size was found to be consistent with the analysis of the comet's syndyne lines. The debiased polarization of the coma was ˜0 per cent in the phase angle range from 172.9° to 177.6°. . No convincing evidence of temporal variation of the polarization was detected.

  16. Continuous-wave circular polarization terahertz imaging

    NASA Astrophysics Data System (ADS)

    Martin, Jillian P.; Joseph, Cecil S.; Giles, Robert H.

    2016-07-01

    Biomedical applications of terahertz (THz) radiation are appealing because THz radiation is nonionizing and has the demonstrated ability to detect intrinsic contrasts between cancerous and normal tissue. A linear polarization-sensitive detection technique for tumor margin delineation has already been demonstrated; however, utilization of a circular polarization-sensitive detection technique has yet to be explored at THz frequencies. A reflective, continuous-wave THz imaging system capable of illuminating a target sample at 584 GHz with either linearly or circularly polarized radiation, and capable of collecting both cross- and copolarized signals remitted from the target, is implemented. To demonstrate the system's utility, a fresh ex vivo human skin tissue specimen containing nonmelanoma skin cancer was imaged. Both polarization-sensitive detection techniques showed contrast between tumor and normal skin tissue, although some differences in images were observed between the two techniques. Our results indicate that further investigation is required to explain the contrast mechanism, as well as to quantify the specificity and sensitivity of the circular polarization-sensitive detection technique.

  17. Procedure for Detecting Outliers in a Circular Regression Model

    PubMed Central

    Rambli, Adzhar; Abuzaid, Ali H. M.; Mohamed, Ibrahim Bin; Hussin, Abdul Ghapor

    2016-01-01

    A number of circular regression models have been proposed in the literature. In recent years, there is a strong interest shown on the subject of outlier detection in circular regression. An outlier detection procedure can be developed by defining a new statistic in terms of the circular residuals. In this paper, we propose a new measure which transforms the circular residuals into linear measures using a trigonometric function. We then employ the row deletion approach to identify observations that affect the measure the most, a candidate of outlier. The corresponding cut-off points and the performance of the detection procedure when applied on Down and Mardia’s model are studied via simulations. For illustration, we apply the procedure on circadian data. PMID:27064566

  18. Observations of Large Scale Sidereal Anisotropy in 1 and 11 TeV cosmic rays from the MINOS experiment

    SciTech Connect

    de Jong, J.K.

    2012-01-01

    The MINOS Near and Far Detectors are two large, functionally-identical, steel-scintillating sampling calorimeters located at depths of 220 mwe and 2100 mwe respectively. The detectors observe the muon component of hadronic showers produced from cosmic ray interactions with nuclei in the earth's atmosphere. From the arrival direction of these muons, the anisotropy in arrival direction of the cosmic ray primaries can be determined. The MINOS Near and Far Detector have observed anisotropy on the order of 0.1% at 1 and 11 TeV respectively. The amplitude and phase of the first harmonic at 1 TeV are 8.2 {+-} 1.7(stat.) x 10{sup -4} and (8.9 {+-} 12.1(stat.)){sup o}, and at 11 TeV are 3.8 {+-} 0.5(stat.) x 10{sup -4} and (27.2 {+-} 7.2(stat.)){sup o}.

  19. Large-scale thermodynamical and dynamical controls on subtropical cloud variability in observations and CMIP3 and CMIP5 models

    NASA Astrophysics Data System (ADS)

    Myers, T. A.; Norris, J. R.

    2013-12-01

    Uncertainty in radiative feedbacks associated with marine boundary cloud changes over the eastern subtropical oceans was a dominant contributor to the spread of climate sensitivity estimates among models of phase 3 of the Coupled Model Intercomparison Project (CMIP3). The present study compares the interannual sensitivity of boundary layer clouds and overlying high-level clouds to large-scale thermodynamical and dynamical variations in observations, CMIP3 models, and CMIP5 models. In observations, greater outgoing shortwave radiation due to clouds is associated with cooler sea-surface temperature, a stronger temperature inversion above cloud top, a moister free troposphere (thermodynamics), faster surface wind speed, and weaker subsidence (dynamics). More shortwave reflection, generally caused by increased low-level cloud fraction, acts to cool the climate system. One third of CMIP3 models simulate within the range of observational uncertainty each of the observed linear regression coefficients between top-of-atmosphere shortwave cloud radiative effect and the large-scale thermodynamics and dynamics, while only one fourth of CMIP5 models do so. Fewer than half of the simulated regression coefficients of the shortwave cloud radiative effect with respect to variations in surface wind speed are within the range of observational uncertainty in both CMIP3 and CMIP5 models. Interestingly, the regression coefficients for shortwave cloud radiative effect on sea-surface temperature and inversion strength are more poorly simulated in CMIP5 than CMIP3. On this basis, the simulation of subtropical marine boundary layer cloud variability has deteriorated from CMIP3 to CMIP5. In observations, reduced outgoing longwave radiation due to clouds is associated with a moister free troposphere and weaker subsidence. Less outgoing radiation, caused by increased high-level cloud fraction, acts to warm the climate system. These regression coefficients are well simulated by CMIP3 and CMIP5

  20. Observational constraint of drizzle properties and processes in large-eddy simulations from two models with size-resolved microphysics

    NASA Astrophysics Data System (ADS)

    Fridlind, A. M.; Remillard, J.; Ackerman, A. S.; Mechem, D. B.; Kollias, P.; Luke, E. P.; Chuang, P. Y.; Witte, M.; Wood, R.

    2015-12-01

    From the CAP-MBL long-term measurement campaign over the Azores, two low-cloud periods are selected via analysis of ISCCP cloud property matrices. Each is a persistent instance of a low-cloud weather state that the GISS climate model severely underpredicts both over the Azores and globally. Meteorologically, one period is characterized by shallow cumulus clouds in a cold-air outbreak behind a cold front, and the other by overcast stratocumulus clouds in a region dominated by a high-pressure system. Observations and MERRA reanalysis are used to derive specifications used for large-eddy simulations (LES) of each period. For both periods, 6-hour and longer simulations with periodic boundary conditions and uniform large-scale forcings over 10 to 100-km domains capture the structural differences between the two low-cloud periods, only modestly influenced by domain size. Simulations of both periods underestimate sub-mesoscale variability, but represent distributions of cloud top, cloud base, and drizzle extents reasonably well in comparison with observations. Simulated mean Doppler velocities as a function of reflectivity also reproduce observed relationships reasonably well; the most notable deviation is lesser-than-observed Doppler velocity where reflectivity exceeds about -10 dBZ, which occurs only in the cumulus case. However, the range of simulated spectral skewness is substantially underestimated in both cases. To help identify likely causes, the overcast stratocumulus case is also simulated with an independent LES code with size-resolved microphysics, which exhibits some similar biases. Although unavailable from CAP-MBL, in situ measurements of drizzle size distribution from two other campaigns are used to gain insight into the biases. Finally, the significance of Doppler moment biases is evaluated in part by deriving autoconversion and accretion parameterization expressions from simulations with varying collision-coalescence kernel assumptions.

  1. Circular piezoelectric bender laser tuners

    NASA Technical Reports Server (NTRS)

    Mcelroy, J. H.; Thompson, P. E.; Walker, H. E.; Johnson, E. H.; Radecki, D. J.; Reynolds, R. S.

    1972-01-01

    The circular piezoelectric bender laser tuner to replace conventional laser tuners when mirror diameters up to 0.50 inch are sufficient is described. The circular piezoelectric bender laser tuner offers much higher displacements per applied volt and permits laser control circuits to be fabricated using standard operational amplifiers, rather than the expensive high-voltage amplifiers required by conventional tuners. The cost of the device is more than one order of magnitude lower than conventional tuners and the device is very rugged with all mechanical resonances easily designed to be greater than 3kHz. In addition to its use as a laser frequency tuner, the circular bender tuner should find many applications in interferometers and similar devices.

  2. Photoelectron circular dichroism of isopropanolamine

    NASA Astrophysics Data System (ADS)

    Catone, D.; Turchini, S.; Contini, G.; Prosperi, T.; Stener, M.; Decleva, P.; Zema, N.

    2017-01-01

    Spectroscopies based on circular polarized light are sensitive to the electronic and structural properties of chiral molecules. Photoelectron circular dichroism (PECD) is a powerful technique that combines the chiral sensitivity of the circular polarized light and the electronic information obtained by photoelectron spectroscopy. An experimental and theoretical PECD study of the outer valence and C 1s core states of 1-amino-2-propanol in the gas phase is presented. The experimental dichroic dispersions in the photoelectron kinetic energy are compared with theoretical calculations employing a multicentric basis set of B-spline functions and a Kohn-Sham Hamiltonian. In order to understand analogies and differences in the dichroism of structural isomers bearing the same functional groups, a comparison with previous PECD study of valence band of 2-amino-1-propanol is carried out.

  3. ON THE 2012 OCTOBER 23 CIRCULAR RIBBON FLARE: EMISSION FEATURES AND MAGNETIC TOPOLOGY

    SciTech Connect

    Yang, Kai; Guo, Yang; Ding, M. D. E-mail: dmd@nju.edu.cn

    2015-06-20

    Circular ribbon flares are usually related to spine-fan type magnetic topology containing null points. In this paper, we investigate an X-class circular ribbon flare on 2012 October 23, using the multiwavelength data from the Solar Dynamics Observatory, Hinode, and RHESSI. In Ca ii H emission, the flare showed three ribbons with two highly elongated ones inside and outside a quasi-circular one, respectively. A hot channel was displayed in the extreme-ultraviolet emissions that infers the existence of a magnetic flux rope. Two hard X-ray (HXR) sources in the 12–25 keV energy band were located at the footpoints of this hot channel. Using a nonlinear force-free magnetic field extrapolation, we identify three topological structures: (1) a three-dimensional null point, (2) a flux rope below the fan of the null point, and (3) a large-scale quasi-separatrix layer (QSL) induced by the quadrupolar-like magnetic field of the active region. We find that the null point is embedded within the large-scale QSL. In our case, all three identified topological structures must be considered to explain all the emission features associated with the observed flare. Besides, the HXR sources are regarded as the consequence of the reconnection within or near the border of the flux rope.

  4. Hα Line Impact Linear Polarization Observed in the 23 July 2002 Flare with the Large Solar Vacuum Telescope (LSVT)

    NASA Astrophysics Data System (ADS)

    Firstova, N. M.; Polyakov, V. I.; Firstova, A. V.

    2012-08-01

    We present the results of studying the proton flare 2B/X4.8 on 23 July 2002, observed with the Large Solar Vacuum Telescope (LSVT) at the Baikal Astrophysical Observatory in spectropolarimetric mode with high spatial and spectral resolution. We have found some evidence for Hα line impact linear polarization, predominantly during the initial moments of the flare. For the Hα line 606 cuts were made along the dispersion in 53 spectrograms, and a polarization signal was found more or less confidently in 60 cuts (13 spectrograms). Polarization was mainly observed in one of the kernels of the flare. A particular feature of this kernel was that the Hα line was observed to show a reversal in the central part of this kernel, which created a dip in the kernel center in the photometric cut. The size of these dips and the size of the sites with the linear polarization coincide and are equal to 3 - 6 arcsec. The maximum polarization degree in this kernel reached 15 %. The direction of the polarization in the kernel is radial, except for the first two frames, where the direction of the polarization was both radial and tangential. Furthermore, we found an analogy between the effects observed at the chromospheric level in this kernel (polarization and depression in Hα line) and the temporal variation of the HXR sources.

  5. SPATIAL SEISMOLOGY OF A LARGE CORONAL LOOP ARCADE FROM TRACE AND EIT OBSERVATIONS OF ITS TRANSVERSE OSCILLATIONS

    SciTech Connect

    Verwichte, E.; Foullon, C.; Van Doorsselaere, T.

    2010-07-01

    We present a study of transverse loop oscillations in a large coronal loop arcade, using observations from the Transition Region And Coronal Explorer (TRACE) and Extreme-ultraviolet Imaging Telescope (EIT). For the first time we reveal the presence of long-period transverse oscillations with periods between 24 minutes and 3 hr. One loop bundle, 690 Mm long and with an oscillation period of 40 minutes, is analyzed in detail and its oscillation characteristics are determined in an automated manner. The oscillation quality factor is similar to what has been found earlier for oscillations in much shorter loops. This indicates that the damping mechanism of transverse loop oscillations is independent of loop length or period. The displacement profile along the whole length of the oscillating loop is determined for the first time and consistently between TRACE and EIT. By comparing the observed profile with models of the three-dimensional geometry of the equilibrium and perturbed loop, we test the effect of longitudinal structuring (spatial seismology) and find that the observations cannot unambiguously distinguish between structuring and non-planarity of the equilibrium loop. Associated intensity variations with a similar periodicity are explained in terms of variations in the line-of-sight column depth. Also, we report intensity oscillations at the loop footpoint, which are in anti-phase with respect to the intensity oscillations in the loop body. Lastly, this observation offers the first opportunity to use the transverse oscillations of the arcade to model the Alfven speed profile in the global corona.

  6. TWO EPOCHS OF VERY LARGE ARRAY OBSERVATIONS OF WATER MASER EMISSION IN THE ACTIVE GALAXY NGC 6240

    SciTech Connect

    Hagiwara, Yoshiaki

    2010-12-15

    Studies of 22 GHz H{sub 2}O maser emission from the merging galaxy NGC 6240 with double nuclei are presented. Two epochs of Very Large Array (VLA) observations in the A-configuration in spectral-line mode were carried out at 0.1 arcsec resolution by covering the redshifted velocity range of {approx}300 km s{sup -1} with respect to the systemic velocity of the galaxy. The purpose of these new observations is twofold: to detect an H{sub 2}O maser that an earlier VLA observation pinpointed in the southern nucleus in the northern nucleus as well to clarify the kinematics of the double nuclei, and to understand the origin of the maser in the galaxy. In the second epoch, one velocity feature peaking at V{sub LSR} = 7491.1 km s{sup -1}, redshifted by {approx}200 km s{sup -1} relative to the systemic velocity, was detected only toward the southern nucleus. The detection of an H{sub 2}O maser feature at or near this velocity had never been reported in earlier observations. However, including the known velocity features at redshifted velocities, no other velocity features were observed toward either nuclei throughout these epochs. The maser remains unresolved at an angular resolution of {approx}0.''1, corresponding to a linear size of less than about 45 pc. The two epochs of VLA observations show that the maser intensity is variable on timescales of at least three months, while the correlation between the maser intensity and the radio continuum intensity is not certain from our data. It is plausible that the maser in NGC 6240 is associated with the activity of an active galactic nucleus in the southern nucleus. Alternatively, the maser can be explained by star-forming activity at the site of massive star formation in the galaxy.

  7. The Role of Large-Coherent-Eddy Transport in the Atmospheric Surface Layer Based on CASES-99 Observations

    NASA Astrophysics Data System (ADS)

    Sun, Jielun; Lenschow, Donald H.; LeMone, Margaret A.; Mahrt, Larry

    2016-07-01

    The analysis of momentum and heat fluxes from the Cooperative Atmosphere-Surface Exchange Study 1999 (CASES-99) field experiment is extended throughout the diurnal cycle following the investigation of nighttime turbulence by Sun et al. (J Atmos Sci 69:338-351, 2012). Based on the observations, limitations of Monin-Obukhov similarity theory (MOST) are examined in detail. The analysis suggests that strong turbulent mixing is dominated by relatively large coherent eddies that are not related to local vertical gradients as assumed in MOST. The HOckey-Stick Transition (HOST) hypothesis is developed to explain the generation of observed large coherent eddies over a finite depth and the contribution of these eddies to vertical variations of turbulence intensity and atmospheric stratification throughout the diurnal cycle. The HOST hypothesis emphasizes the connection between dominant turbulent eddies and turbulence generation scales, and the coupling between the turbulence kinetic energy and the turbulence potential energy within the turbulence generation layer in determining turbulence intensity. For turbulence generation directly influenced by the surface, the HOST hypothesis recognizes the role of the surface both in the vertical variation of momentum and heat fluxes and its boundary effect on the size of the dominant turbulence eddies.

  8. Large-scale variations of the interplanetary magnetic field: Voyager 1 and 2 observations between 1-5 AU

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Lepping, R. P.; Behannon, K. W.; Klein, L. W.; Neubauer, F. M.

    1981-01-01

    Observations by the Voyager 1 and 2 spacecraft of the interplanetary magnetic field between 1 and 5 AU were used to investigate the large scale structure of the IMF in a period of increasing solar activity. The Voyager spacecraft found notable deviations from the Parker axial model. These deviations are attributed both to temporal variations associated with increasing solar activity, and to the effects of fluctuations of the field in the radial direction. The amplitude of the latter fluctuations were found to be large relative to the magnitude of the radial field component itself beyond approximately 3 AU. Both Voyager 1 and Voyager 2 observed decreases with increasing heliocentric distance in the amplitude of transverse fluctuations in the averaged field strength (B) which are consistent with the presence of predominantly undamped Alfven waves in the solar wind, although and necessarily implying the presence of them. Fluctuations in the strength of B (relative to mean field strength) were found to be small in amplitude, with a RMS which is approximately one third of that for the transverse fluctuations and they are essentially independent of distance from the Sun.

  9. LUPUS I observations from the 2010 flight of the Balloon-borne large aperture submillimeter telescope for polarimetry

    SciTech Connect

    Matthews, Tristan G.; Chapman, Nicholas L.; Novak, Giles; Ade, Peter A. R.; Hargrave, Peter C.; Nutter, David; Angilè, Francesco E.; Devlin, Mark J.; Klein, Jeffrey; Benton, Steven J.; Fissel, Laura M.; Gandilo, Natalie N.; Netterfield, Calvin B.; Chapin, Edward L.; Fukui, Yasuo; Gundersen, Joshua O.; Korotkov, Andrei L.; Moncelsi, Lorenzo; Mroczkowski, Tony K.; Olmi, Luca; and others

    2014-04-01

    The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) was created by adding polarimetric capability to the BLAST experiment that was flown in 2003, 2005, and 2006. BLASTPol inherited BLAST's 1.8 m primary and its Herschel/SPIRE heritage focal plane that allows simultaneous observation at 250, 350, and 500 μm. We flew BLASTPol in 2010 and again in 2012. Both were long duration Antarctic flights. Here we present polarimetry of the nearby filamentary dark cloud Lupus I obtained during the 2010 flight. Despite limitations imposed by the effects of a damaged optical component, we were able to clearly detect submillimeter polarization on degree scales. We compare the resulting BLASTPol magnetic field map with a similar map made via optical polarimetry. (The optical data were published in 1998 by J. Rizzo and collaborators.) The two maps partially overlap and are reasonably consistent with one another. We compare these magnetic field maps to the orientations of filaments in Lupus I, and we find that the dominant filament in the cloud is approximately perpendicular to the large-scale field, while secondary filaments appear to run parallel to the magnetic fields in their vicinities. This is similar to what is observed in Serpens South via near-IR polarimetry, and consistent with what is seen in MHD simulations by F. Nakamura and Z. Li.

  10. Paired circularly polarized heterodyne ellipsometer

    SciTech Connect

    Yu, C.-J.; Lin, C.-E.; Yu, L.-P.; Chou, C

    2009-02-01

    We develop a paired circularly polarized heterodyne ellipsometer (PCPHE), in which a heterodyne interferometer based on a two-frequency circularly polarized laser beam is set up. It belongs to an amplitude-sensitive ellipsometer that is able to provide not only a wider dynamic range of polarization modulation frequency but also a higher detection sensitivity than that of a conventional photometric ellipsometer. A real-time and precise measurement of ellipsometric parameters, which demonstrated an accuracy of less than 1 nm on thickness measurement of SiO2 thin film deposited on silicon substrate, can be applied with the PCPHE.

  11. Circular-polarization ratios for aggregates of spherical particles

    NASA Astrophysics Data System (ADS)

    Virkki, A.; Muinonen, K.; Penttilä, A.

    2012-04-01

    A basic strategy for observing a small solar-system object using radar is to measure the distribution of echo power in time delay and Doppler frequency for a circularly polarized transmitted wave, in the same and opposite senses of circular polarization. The measurement can be repeated for differing orientations and plane-of-sky directions of the object. The circular-polarization ratio μ is the ratio of the echo power in the same circular-polarization state (SC) to that in the opposite circular-polarization state (OC). The ratio μ is often the most important physical observable with the radar technique, as it provides the best indications for wavelength-scale complexity of the surface. At the typical transmitter frequencies of 2380 MHz or 8495 MHz, the wavelengths are 12.6 cm or 3.5 cm, respectively. We model electromagnetic scattering from closely-packed random aggregates of spheres imitating the structure of an asteroid's regolith. Both scattering and absorption of the electromagnetic wave are treated. The Multiple-Sphere T -Matrix Method computer software (MSTM; D. W. Mackowski and M. I. Mishchenko, JQSRT 112, 1282, 2011) is utilized to study how different parameters affect the circular-polarization ratio, e.g., the size distribution and electric permittivities of the spherical particles forming the different aggregates. Our primary goal is to see if the computed circular-polarization ratios can be linked to the observational data of asteroids detected with radar. The results of the simulations show striking structure for the circular-polarization ratio as a function of the size parameter and the electric permittivity of the medium. Also differences between aggregates of monodisperse and polydisperse spheres clearly exist: the aggregates consisting of polydisperse spherical particles, and hence, showing more complex structure and surface, result in circular-polarization ratios higher than the aggregates of monodisperse spherical particles, probably due to the

  12. Overlap statistics of shallow boundary layer clouds: comparing ground-based observations with large-eddy simulations

    NASA Astrophysics Data System (ADS)

    Orlandi, Emiliano; Corbetta, Gabriele; Heus, Thijs; Neggers, Roel; Crewell, Susanne

    2016-04-01

    As large-scale models for weather and climate have coarse spatial resolutions, they cannot resolve clouds within a vertical grid column and thus rely on parameterizations, leading to uncertainty in the representation of clouds and the way they overlap in the vertical. The uncertainty in the cloud overlap parameterizations remains a significant source of error in the Earth's radiation budget in general circulation models (GCMs). Most studies concerning cloud overlap mainly focused on either large ensemble of cloud types or deep convective cloud fields. Cumuliform boundary layer cloud fields have been less researched despite the fact that their irregularity in shape and in spatial distribution at subgrid scales can impact the cloud overlap significantly. In this study, high-resolution ground-based measurements are used to assess the realism of fine-scale numerical simulations of shallow cumulus cloud fields. The overlap statistics of cumuli as produced by i) local large-eddy simulations (LES) as well as ii) the big-domain ICON at cloud resolving resolutions are confronted with CloudNet datasets at the Jülich ObservatorY for Cloud Evolution (JOYCE). Cloud fraction masks are derived for five different cases during the April-August 2013 period, using gridded time-height datasets at various temporal and vertical resolutions. The overlap ratio (R), i.e. the ratio between cloud fraction by volume and by area, is studied as a function of the vertical resolution. Good agreement is found between R derived from observations and simulations. Simulated and observed decorrelation lengths are smaller (< 300 m) than previously reported (> 1 km). A similar diurnal variation in the overlap efficiency is found in observations and simulations. The inefficient overlap we found at sub-grid vertical scales has the potential of significantly affecting the vertical transfer of radiation, yet few GCMs take such overlap at small, unresolved scales into account. A better understanding of the

  13. Maximal dinucleotide and trinucleotide circular codes.

    PubMed

    Michel, Christian J; Pellegrini, Marco; Pirillo, Giuseppe

    2016-01-21

    We determine here the number and the list of maximal dinucleotide and trinucleotide circular codes. We prove that there is no maximal dinucleotide circular code having strictly less than 6 elements (maximum size of dinucleotide circular codes). On the other hand, a computer calculus shows that there are maximal trinucleotide circular codes with less than 20 elements (maximum size of trinucleotide circular codes). More precisely, there are maximal trinucleotide circular codes with 14, 15, 16, 17, 18 and 19 elements and no maximal trinucleotide circular code having less than 14 elements. We give the same information for the maximal self-complementary dinucleotide and trinucleotide circular codes. The amino acid distribution of maximal trinucleotide circular codes is also determined.

  14. Observational requirements for Lyα forest tomographic mapping of large-scale structure at z ∼ 2

    SciTech Connect

    Lee, Khee-Gan; Hennawi, Joseph F.; White, Martin; Croft, Rupert A. C.; Ozbek, Melih

    2014-06-10

    The z ≳ 2 Lyα forest traces the underlying dark matter distribution on large scales and, given sufficient sightlines, can be used to create three-dimensional (3D) maps of large-scale structures. We examine the observational requirements to construct such maps and estimate the signal-to-noise as a function of exposure time and sightline density. Sightline densities at z = 2.25 are n {sub los} ≈ [360, 1200, 3300] deg{sup –2} at limiting magnitudes of g = [24.0, 24.5, 25.0], resulting in transverse sightline separations of (d ) ≈ [3.6, 1.9, 1.2] h {sup –1} Mpc, which roughly sets the reconstruction scale. We simulate these reconstructions using mock spectra with realistic noise properties and find that spectra with S/N ≈ 4 per angstrom can be used to generate maps that clearly trace the underlying dark matter at overdensities of ρ/(ρ) ∼ 1. For the VLT/VIMOS spectrograph, exposure times t {sub exp} = [4, 6, 10] hr are sufficient for maps with spatial resolution ε{sub 3D} = [5.0, 3.2, 2.3] h {sup –1} Mpc. Assuming ∼250 h {sup –1} Mpc is probed along the line of sight, 1 deg{sup 2} of survey area would cover a comoving volume of ≈10{sup 6} h {sup –3} Mpc{sup 3} at (z) ∼ 2.3, enabling the efficient mapping of large volumes with 8-10 m telescopes. These maps could be used to study galaxy environments, the topology of large-scale structures at high z, and to detect proto-clusters.

  15. Dissecting the secondary structure of the circular RNA of a nuclear viroid in vivo: A "naked" rod-like conformation similar but not identical to that observed in vitro.

    PubMed

    López-Carrasco, Amparo; Flores, Ricardo

    2016-08-30

    With a minimal (250-400 nt), non-protein-coding, circular RNA genome, viroids rely on sequence/structural motifs for replication and colonization of their host plants. These motifs are embedded in a compact secondary structure whose elucidation is crucial to understand how they function. Viroid RNA structure has been tackled in silico with algorithms searching for the conformation of minimal free energy, and in vitro by probing in solution with RNases, dimethyl sulphate and bisulphite, and with selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE), which interrogates the RNA backbone at single-nucleotide resolution. However, in vivo approaches at that resolution have not been assayed. Here, after confirming by 3 termodynamics-based predictions and by in vitro SHAPE that the secondary structure adopted by the infectious monomeric circular (+) RNA of potato spindle tuber viroid (PSTVd) is a rod-like conformation with double-stranded segments flanked by loops, we have probed it in vivo with a SHAPE modification. We provide direct evidence that a similar, but not identical, rod-like conformation exists in PSTVd-infected leaves of Nicotiana benthamiana, verifying the long-standing view that this RNA accumulates in planta as a "naked" form rather than tightly associated with protecting host proteins. However, certain nucleotides of the central conserved region, including some of the loop E involved in key functions such as replication, are more SHAPE-reactive in vitro than in vivo. This difference is most likely due to interactions with proteins mediating some of these functions, or to structural changes promoted by other factors of the in vivo habitat.

  16. Satellite observations of energy-banded ions during large geomagnetic storms: Event studies, statistics, and comparisons to source models

    NASA Astrophysics Data System (ADS)

    Colpitts, C. A.; Cattell, C. A.; Kozyra, J. U.; Thomsen, M. F.; Lavraud, B.

    2016-07-01

    Energy-banded ions from tens to ten thousands of eV are observed in the low-latitude auroral and subauroral zones during every large (minimum Dst < -150 nT) geomagnetic storm encountered by the FAST satellite. The banded ions persist for many FAST orbits, lasting up to 12 h, in both the northern and southern hemispheres. The energy-banded ions often have more than six distinct bands, and the O+, He+, and H+ bands are often observed at the same energies. The bands are extensive in latitude (~50-75° on the dayside, often extending to 45°) and magnetic local time, covering all magnetic local time over the data set of storms. The distributions are peaked in the perpendicular direction at the altitudes of the FAST satellite (~350-4175 km), although in some cases the precipitating component dominates for the lowest energy bands. At the same time, for some of the events studied in detail, long-lasting intervals of field-aligned energy dispersed ions from ~100 eV to 40 keV are seen in Los Alamos National Laboratory geosynchronous observations, primarily on the dayside and after magnetosheath encounters (i.e., highly compressed magnetosphere). We present both case and statistical studies of the banded ions. These bands are a new phenomenon associated with all large storms, which are distinctly different from other banded populations, and are not readily interpreted using previous models for particle sources, transport, and loss. The energy-banded ions are an energetically important component of the inner magnetosphere during the most intense magnetic storms.

  17. Interaction effect of number of circular holes in a circular plate

    SciTech Connect

    Ukadgaonker, V.G.; Agnahotri, N.A.

    1996-12-01

    The problem of circular tubesheet with uniform tension at its circular boundary and nine holes in the circular pitch pattern at its center is solved using complex stress functions. The Schwarz Alternating Technique is used to find the interaction effect of the holes on each other and then the superposition method is used to obtain desired geometry of the nine holes. This superposition gives the stress free boundary at the central hole exactly satisfied. When these results are compared with those obtained by Ukadgaonker and Kale by Finite Element Method it is found that the theoretical solutions give higher stress concentration than FEM by about 20% for a large outer radius. When the outer radius is reduced the stress concentration factor increases considerably and the difference in the analytical and the FEM solution also increases to a large extent. The analytical solution found in the present paper is verified with the FEM and Photoelasticity solution obtained by Ukadgaonker and Kale (1996) earlier. This problem is further generalized for a rhombic pitch pattern, which can be reduced to particular cases such as square pitch pattern, triangular pitch pattern, diagonal pitch pattern by changing the angle of the rhombus. The stress concentration factor around the central hole varies very little for various ligament efficiencies which is given in percentage.

  18. Improved large-scale hydrological modelling through the assimilation of streamflow and downscaled satellite soil moisture observations

    NASA Astrophysics Data System (ADS)

    López López, Patricia; Wanders, Niko; Schellekens, Jaap; Renzullo, Luigi J.; Sutanudjaja, Edwin H.; Bierkens, Marc F. P.

    2016-07-01

    The coarse spatial resolution of global hydrological models (typically >  0.25°) limits their ability to resolve key water balance processes for many river basins and thus compromises their suitability for water resources management, especially when compared to locally tuned river models. A possible solution to the problem may be to drive the coarse-resolution models with locally available high-spatial-resolution meteorological data as well as to assimilate ground-based and remotely sensed observations of key water cycle variables. While this would improve the resolution of the global model, the impact of prediction accuracy remains largely an open question. In this study, we investigate the impact of assimilating streamflow and satellite soil moisture observations on the accuracy of global hydrological model estimations, when driven by either coarse- or high-resolution meteorological observations in the Murrumbidgee River basin in Australia. To this end, a 0.08° resolution version of the PCR-GLOBWB global hydrological model is forced with downscaled global meteorological data (downscaled from 0.5° to 0.08° resolution) obtained from the WATCH Forcing Data methodology applied to ERA-Interim (WFDEI) and a local high-resolution, gauging-station-based gridded data set (0.05°). Downscaled satellite-derived soil moisture (downscaled from ˜  0.5° to 0.08° resolution) from the remote observation system AMSR-E and streamflow observations collected from 23 gauging stations are assimilated using an ensemble Kalman filter. Several scenarios are analysed to explore the added value of data assimilation considering both local and global meteorological data. Results show that the assimilation of soil moisture observations results in the largest improvement of the model estimates of streamflow. The joint assimilation of both streamflow and downscaled soil moisture observations leads to further improvement in streamflow simulations (20 % reduction in RMSE

  19. Early science with the Large Millimetre Telescope: Deep LMT/AzTEC millimetre observations of ɛ Eridani and its surroundings

    NASA Astrophysics Data System (ADS)

    Chavez-Dagostino, M.; Bertone, E.; Cruz-Saenz de Miera, F.; Marshall, J. P.; Wilson, G. W.; Sánchez-Argüelles, D.; Hughes, D. H.; Kennedy, G.; Vega, O.; De la Luz, V.; Dent, W. R. F.; Eiroa, C.; Gómez-Ruiz, A. I.; Greaves, J. S.; Lizano, S.; López-Valdivia, R.; Mamajek, E.; Montaña, A.; Olmedo, M.; Rodríguez-Montoya, I.; Schloerb, F. P.; Yun, Min S.; Zavala, J. A.; Zeballos, M.

    2016-11-01

    ɛ Eridani is a nearby, young Sun-like star that hosts a ring of cool debris analogous to the Solar system's Edgeworth-Kuiper belt. Early observations at (sub-)mm wavelengths gave tentative evidence of the presence of inhomogeneities in the ring, which have been ascribed to the effect of a putative low eccentricity planet, orbiting close to the ring. The existence of these structures has been recently challenged by high-resolution interferometric millimetre observations. Here, we present the deepest single-dish image of ɛ Eridani at millimetre wavelengths, obtained with the Large Millimetre Telescope Alfonso Serrano (LMT). The main goal of these LMT observations is to confirm (or refute) the presence of non-axisymmetric structure in the disc. The dusty ring is detected for the first time along its full projected elliptical shape. The radial extent of the ring is not spatially resolved and shows no evidence, to within the uncertainties, of dust density enhancements. Additional features of the 1.1 mm map are: (i) the presence of significant flux in the gap between the ring and the star, probably providing the first exo-solar evidence of Poynting-Robertson drag, (ii) an unambiguous detection of emission at the stellar position with a flux significantly above that expected from ɛ Eridani's photosphere, and (iii) the identification of numerous unresolved sources which could correspond to background dusty star-forming galaxies.

  20. Circular Bioassay Platforms for Applications in Microwave-Accelerated Techniques

    PubMed Central

    Mohammed, Muzaffer; Clement, Travis C.; Aslan, Kadir

    2014-01-01

    In this paper, we present the design of four different circular bioassay platforms, which are suitable for homogeneous microwave heating, using theoretical calculations (i.e., COMSOL™ multiphysics software). Circular bioassay platforms are constructed from poly(methyl methacrylate) (PMMA) for optical transparency between 400–800 nm, has multiple sample capacity (12, 16, 19 and 21 wells) and modified with silver nanoparticle films (SNFs) to be used in microwave-accelerated bioassays (MABs). In addition, a small monomode microwave cavity, which can be operated with an external microwave generator (100 W), for use with the bioassay platforms in MABs is also developed. Our design parameters for the circular bioassay platforms and monomode microwave cavity during microwave heating were: (i) temperature profiles, (ii) electric field distributions, (iii) location of the circular bioassay platforms inside the microwave cavity, and (iv) design and number of wells on the circular bioassay platforms. We have also carried out additional simulations to assess the use of circular bioassay platforms in a conventional kitchen microwave oven (e.g., 900 W). Our results show that the location of the circular bioassay platforms in the microwave cavity was predicted to have a significant effect on the homogeneous heating of these platforms. The 21-well circular bioassay platform design in our monomode microwave cavity was predicted to offer a homogeneous heating pattern, where inter-well temperature was observed to be in between 23.72–24.13°C and intra-well temperature difference was less than 0.21°C for 60 seconds of microwave heating, which was also verified experimentally. PMID:25568813

  1. Circular Bioassay Platforms for Applications in Microwave-Accelerated Techniques.

    PubMed

    Mohammed, Muzaffer; Clement, Travis C; Aslan, Kadir

    2014-12-02

    In this paper, we present the design of four different circular bioassay platforms, which are suitable for homogeneous microwave heating, using theoretical calculations (i.e., COMSOL™ multiphysics software). Circular bioassay platforms are constructed from poly(methyl methacrylate) (PMMA) for optical transparency between 400-800 nm, has multiple sample capacity (12, 16, 19 and 21 wells) and modified with silver nanoparticle films (SNFs) to be used in microwave-accelerated bioassays (MABs). In addition, a small monomode microwave cavity, which can be operated with an external microwave generator (100 W), for use with the bioassay platforms in MABs is also developed. Our design parameters for the circular bioassay platforms and monomode microwave cavity during microwave heating were: (i) temperature profiles, (ii) electric field distributions, (iii) location of the circular bioassay platforms inside the microwave cavity, and (iv) design and number of wells on the circular bioassay platforms. We have also carried out additional simulations to assess the use of circular bioassay platforms in a conventional kitchen microwave oven (e.g., 900 W). Our results show that the location of the circular bioassay platforms in the microwave cavity was predicted to have a significant effect on the homogeneous heating of these platforms. The 21-well circular bioassay platform design in our monomode microwave cavity was predicted to offer a homogeneous heating pattern, where inter-well temperature was observed to be in between 23.72-24.13°C and intra-well temperature difference was less than 0.21°C for 60 seconds of microwave heating, which was also verified experimentally.

  2. Accelerator Science: Circular vs. Linear

    ScienceCinema

    Lincoln, Don

    2016-12-14

    Particle accelerator are scientific instruments that allow scientists to collide particles together at incredible energies to study the secrets of the universe. However, there are many manners in which particle accelerators can be constructed. In this video, Fermilab’s Dr. Don Lincoln explains the pros and cons of circular and linear accelerators.

  3. Accelerator Science: Circular vs. Linear

    SciTech Connect

    Lincoln, Don

    2016-11-10

    Particle accelerator are scientific instruments that allow scientists to collide particles together at incredible energies to study the secrets of the universe. However, there are many manners in which particle accelerators can be constructed. In this video, Fermilab’s Dr. Don Lincoln explains the pros and cons of circular and linear accelerators.

  4. Class IIc or Circular Bacteriocins

    NASA Astrophysics Data System (ADS)

    Martin-Visscher, Leah A.; van Belkum, Marco J.; Vederas, John C.

    The circular bacteriocins produced by Gram-positive bacteria represent a diverse class of antimicrobial peptides. These bacteriocins display enhanced stability compared to linear bacteriocins, which arises from their characteristic circular backbone. Currently, eight unique circular bacteriocins have been identified, and analysis of their gene clusters indicates that they likely utilize complex mechanisms for maturation and secretion, as well as for immunity. These bacteriocins target the cytoplasmic membrane of sensitive cells, leading to pore formation that results in loss of ions, dissipation of membrane potential, and ultimately, cell death. Structural studies suggest that despite variation in their sequences, most of these bacteriocins likely adopt a common three-dimensional architecture, consisting of four or five tightly packed helices encompassing a hydrophobic core. There are many mysteries surrounding the biosynthesis of these peptides, particularly in regard to the mechanism by which they are cyclized. Elucidation of such a mechanism may provide exciting new approaches to the bioengineering of new, stable, and antimicrobially active circular peptides.

  5. Stress Analysis of Circular Frames

    NASA Technical Reports Server (NTRS)

    Fahlbusch, H; Wegner, W

    1941-01-01

    The stresses in circular frames of constant bending stiffnesses, as encountered in thin-wall shells, are investigated from the point of view of finite depth of sectional area of frame. The solution is carried out for four fundamental load conditions. The method is illustrated on a worked out example.

  6. Observation of the large scale cosmic-ray anisotropy at TeV energies with the Milagro detector

    NASA Astrophysics Data System (ADS)

    Kolterman, Brian E.

    Cosmic-rays with energies in the range of 1-100 TeV are nearly isotropic in their arrival directions due to interactions with randomly scattered inhomogeneities in the Galactic magnetic field. Observation of the large scale anisotropy in the arrival direction of these cosmic-rays is therefore a useful tool in constraining theoretical models of cosmic-ray propagation, probing the magnetic field structure in our interstellar neighborhood, as well as providing information about the distribution of sources. In this work results are presented of a harmonic analysis of the large scale cosmic-ray anisotropy as observed by the Milagro observatory. A two- dimensional display of the anisotropy projections in right ascension is generated by the fitting of three harmonics to 18 separate declination bands. Milagro is a water Cherenkov detector located at an elevation of 2630m in the Jemez mountains outside of Los Alamos, NM. With a live time > 90 and a large field-of-view (~2 sr), Milagro is an excellent instrument for measuring this anisotropy with high sensitivity at TeV energies. The analysis is conducted using a seven year data sample consisting of more than 95 billion events. A sidereal anisotropy is observed with a magnitude around 0.1% for cosmic-rays with a median energy of 6 TeV. The dominant feature in this data set is a deficit region of depth (-2.85±0.06 stat. ±0.08 syst.)×10 -3 in the direction of the Galactic North Pole with a range in declination of - 10 to 45 degrees and 150 to 225 degrees in right ascension. The anisotropy also shows evidence of a time dependence, with a steady increase in the magnitude of the signal in this region over the course of seven years. An analysis of the energy dependence of the anisotropy in this region is also presented showing possible deviation of the spectral index of the anisotropy signal from that of the nominal cosmic-ray background. The anisotropy of cosmic-rays in universal time is analyzed showing a dipole structure at

  7. MIRO Observations of Millimeter-wave Emission from Large Dust Particles in the Coma of 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Schloerb, F. Peter; Gulkis, Samuel; Biver, Nicolas; von Allmen, Paul; Beaudin, Gerard; Bockelee-Morvan, Dominique; Choukroun, Mathieu; Crovisier, Jacques; Davidsson, Bjorn; Encrenaz, Pierre; Encrenaz, Therese A.; Frerking, Margaret; Hartogh, Paul; Ip, Wing-Huen; Janssen, Michael A.; Jarchow, Christopher; Kareta, Teddy; Lellouch, Emmanuel; Leyrat, Cedric; Rezac, Ladislav; Spilker, Thomas R.

    2016-10-01

    exponents between -1.6 and -2.0 would require the large particles observed by MIRO to disappear on time scales of 20,000-80,000 seconds.

  8. Localization of CO2 Leakage from a Circular Hole on a Flat-Surface Structure Using a Circular Acoustic Emission Sensor Array

    PubMed Central

    Cui, Xiwang; Yan, Yong; Guo, Miao; Han, Xiaojuan; Hu, Yonghui

    2016-01-01

    Leak localization is essential for the safety and maintenance of storage vessels. This study proposes a novel circular acoustic emission sensor array to realize the continuous CO2 leak localization from a circular hole on the surface of a large storage vessel in a carbon capture and storage system. Advantages of the proposed array are analyzed and compared with the common sparse arrays. Experiments were carried out on a laboratory-scale stainless steel plate and leak signals were obtained from a circular hole in the center of this flat-surface structure. In order to reduce the influence of the ambient noise and dispersion of the acoustic wave on the localization accuracy, ensemble empirical mode decomposition is deployed to extract the useful leak signal. The time differences between the signals from the adjacent sensors in the array are calculated through correlation signal processing before estimating the corresponding distance differences between the sensors. A hyperbolic positioning algorithm is used to identify the location of the circular leak hole. Results show that the circular sensor array has very good directivity toward the circular leak hole. Furthermore, an optimized method is proposed by changing the position of the circular sensor array on the flat-surface structure or adding another circular sensor array to identify the direction of the circular leak hole. Experiential results obtained on a 100 cm × 100 cm stainless steel plate demonstrate that the full-scale error in the leak localization is within 0.6%. PMID:27869765

  9. Lunar Maria and circular basins-a review

    USGS Publications Warehouse

    Stuart-Alexander, D. E.; Howard, K.A.

    1970-01-01

    Lunar Orbiter data make it possible to examine the distribution and relations of maria and large circular basins over the entire Moon. The restricted distribution and age of the maria are in marked contrast to the apparently random distribution in time and place of the circular basins, some of which contain mare fillings. The circular basins are believed to be impact scars, and the maria to be volcanic fills which in each case are younger than the structures they fill. Twenty-nine circular basins 300 km wide or wider are recognized. They are placed in an age sequence because successive stages of degradation can be recognized from the fresh Orientale basin to the almost obliterated basin containing Mare Australe. The maria were emplaced during a short span of lunar history, although some light plains of the highlands may be older maria lightened through age. The present maria are topographically low, tend to be associated with large circular basins, and lie in a crude global belt of regional concentrations; 94% are on the hemisphere facing the Earth. Possible explanations offered for these patterns of mare distribution include impact-induced volcanism, volcanic extrusion to a hydrostatic level, isostatic compensation, lateral heterogeneity in the lunar interior, subcrustal convection, and volcanism due to disruption by Earth's gravity. ?? 1970.

  10. Chandra, Extreme Ultraviolet Explorer, and Very Large Array Observations of the Active Binary System σ2 Coronae Borealis

    NASA Astrophysics Data System (ADS)

    Osten, Rachel A.; Ayres, Thomas R.; Brown, Alexander; Linsky, Jeffrey L.; Krishnamurthi, Anita

    2003-01-01

    We present the results of a coordinated observing campaign on the short-period RS CVn binary σ2 Coronae Borealis (F6V+G0V Porb=1.14 days) with the Very Large Array, the Extreme Ultraviolet Explorer, and the Chandra X-Ray Observatory High-Energy Transmission Grating Spectrometer. The radio emission is consistent with previously determined quiescent gyrosynchrotron properties. Multiple flares were seen with Extreme Ultraviolet Explorer, five occurring within two consecutive orbital periods. The first of these flares was observed with Chandra. The Chandra observations of σ2 CrB showed no systematic variations of line fluxes, widths, or Doppler shifts with orbital phase, nor any response in line width or offset due to the flare. This is consistent with both stars being equally active coronal emitters. We have developed a self-consistent method of spectral analysis to derive information from the line and continuum emissions concerning the distribution of plasma with temperature and elemental abundances. A bimodal temperature distribution is appropriate for both quiescent and flare intervals, with a stable peak at 6-8 MK and another variable enhancement at higher temperatures, with evidence for significant contribution from temperatures up to 50 MK during the flare, compared to 30 MK during quiescence. The iron abundance is subsolar during quiescence but is enriched by about a factor of 2 during a large flare seen with Chandra. The noble gas elements neon and argon show elevated abundances with respect to iron, but there is no clear evidence for any first ionization potential-based abundance pattern during quiescence or the flare. We have determined coronal electron densities from the helium-like ions O VII, Ne IX, Mg XI, and Si XIII, which imply densities >=1010 cm-3. There is a small enhancement in the electron densities derived for the flare, but it is not statistically significant. We call attention to electron temperature constraints provided by the ratios of 1s2

  11. Direct single-molecule observations of DNA unwinding by SV40 large tumor antigen under a negative DNA supercoil state.

    PubMed

    Takahashi, Shunsuke; Motooka, Shinya; Kawasaki, Shohei; Kurita, Hirofumi; Mizuno, Takeshi; Matsuura, Shun-Ichi; Hanaoka, Fumio; Mizuno, Akira; Oshige, Masahiko; Katsura, Shinji

    2017-01-05

    Superhelices, which are induced by the twisting and coiling of double-helical DNA in chromosomes, are thought to affect transcription, replication, and other DNA metabolic processes. In this study, we report the effects of negative supercoiling on the unwinding activity of simian virus 40 large tumor antigen (SV40 TAg) at a single-molecular level. The supercoiling density of linear DNA templates was controlled using magnetic tweezers and monitored using a fluorescent microscope in a flow cell. SV40 TAg-mediated DNA unwinding under relaxed and negative supercoil states was analyzed by the direct observation of both single- and double-stranded regions of single DNA molecules. Increased negative superhelicity stimulated SV40 TAg-mediated DNA unwinding more strongly than a relaxed state; furthermore, negative superhelicity was associated with an increased probability of SV40 TAg-mediated DNA unwinding. These results suggest that negative superhelicity helps to regulate the initiation of DNA replication.

  12. A particle consistent with the Higgs boson observed with the ATLAS detector at the Large Hadron Collider.

    PubMed

    2012-12-21

    Nearly 50 years ago, theoretical physicists proposed that a field permeates the universe and gives energy to the vacuum. This field was required to explain why some, but not all, fundamental particles have mass. Numerous precision measurements during recent decades have provided indirect support for the existence of this field, but one crucial prediction of this theory has remained unconfirmed despite 30 years of experimental searches: the existence of a massive particle, the standard model Higgs boson. The ATLAS experiment at the Large Hadron Collider at CERN has now observed the production of a new particle with a mass of 126 giga-electron volts and decay signatures consistent with those expected for the Higgs particle. This result is strong support for the standard model of particle physics, including the presence of this vacuum field. The existence and properties of the newly discovered particle may also have consequences beyond the standard model itself.

  13. Observation of energetic-ion losses induced by various MHD instabilities in the Large Helical Device (LHD)

    NASA Astrophysics Data System (ADS)

    Ogawa, K.; Isobe, M.; Toi, K.; Watanabe, F.; Spong, D. A.; Shimizu, A.; Osakabe, M.; Ohdachi, S.; Sakakibara, S.; LHD Experiment Group

    2010-08-01

    Energetic-ion losses induced by toroidicity-induced Alfvén eigenmodes (TAEs) and resistive interchange modes (RICs) were observed in neutral-beam heated plasmas of the Large Helical Device (LHD) at a relatively low toroidal magnetic field level (<=0.75 T). The energy and pitch angle of the lost ions are detected using a scintillator-based lost-fast ion probe. Each instability increases the lost ions having a certain energy/pitch angle. TAE bursts preferentially induce energetic beam ions in co-passing orbits having energy from the injection energy E = 190 keV down to 130 keV, while RICs expel energetic ions of E = 190 keV down to ~130 keV in passing-toroidally trapped boundary orbits. Loss fluxes induced by these instabilities increase with different dependences on the magnetic fluctuation amplitude: nonlinear and linear dependences for TAEs and RICs, respectively.

  14. A large increase in U.S. methane emissions over the past decade inferred from satellite data and surface observations

    NASA Astrophysics Data System (ADS)

    Turner, A. J.; Jacob, D. J.; Benmergui, J.; Wofsy, S. C.; Maasakkers, J. D.; Butz, A.; Hasekamp, O.; Biraud, S. C.

    2016-03-01

    The global burden of atmospheric methane has been increasing over the past decade, but the causes are not well understood. National inventory estimates from the U.S. Environmental Protection Agency indicate no significant trend in U.S. anthropogenic methane emissions from 2002 to present. Here we use satellite retrievals and surface observations of atmospheric methane to suggest that U.S. methane emissions have increased by more than 30% over the 2002-2014 period. The trend is largest in the central part of the country, but we cannot readily attribute it to any specific source type. This large increase in U.S. methane emissions could account for 30-60% of the global growth of atmospheric methane seen in the past decade.

  15. Circular Polarization in AGNs: Polarity and Spectra

    NASA Astrophysics Data System (ADS)

    Aller, M. F.; Aller, H. D.; Plotkin, R. M.

    2005-12-01

    Circular polarization (Stokes V) observations potentially provide information on the nature and origin of the underlying magnetic fields in AGNs. We have been systematically monitoring a group of sources with detectable circular polarization (V>0.1 percent, a level set by the instrumental polarization of our system) in all 4 Stokes parameters at 8.0 and 4.8 GHz since 2000, and also at 14.5 GHz since November 2003, with the University of Michigan prime focus paraboloid antenna. These data are compared with historical observations obtained with the same instrument at 8.0 and 4.8 GHz extending back to 1978. Specific goals are to study the temporal spectral behavior of Stokes V and its relation to variability in total flux and linear polarization, and to investigate the question of polarity stability on decade-long time scales using data obtained with the same instrumentation and at the same frequencies. The data are consistent with linear-to-circular mode conversion in partially opaque regions of the source. We find examples of polarity changes with time at one or more frequencies associated with outbursts in total flux and linear polarization, and polarity differences within the 3 frequencies at a single epoch in one case, 3C 279. Such behavior argues against the notion that the sign of Stokes V is a simple tracer of the net flow of magnetic energy from the central engine to the jet or an indicator of the direction of rotation of the spinning central black hole/accretion disk via the winding up of the initial seed magnetic field. This work was supported in part by NSF grant AST-0307629 and by funds from the University of Michigan.

  16. The observation of large semi-major axis Centaurs: Testing for the signature of a planetary-mass solar companion

    NASA Astrophysics Data System (ADS)

    Gomes, Rodney S.; Soares, Jean S.; Brasser, Ramon

    2015-09-01

    Several objects whose perihelion lies between Jupiter and Neptune have large semi-major axes a > 100 au, two of them having semi-major axis above 1000 au. Since these objects' perihelia share the same region as the classical Centaurs, a coherent nomenclature for them could be large semi-major axis Centaurs (Laces). It has been argued that the classical Centaurs, with semi-major axes below 50 au, originate from the Scattered Disk. However, the Laces most likely originate from the Oort Cloud. We determine the brightest object in the Laces, classical Centaurs (with semi-major axis >20 au) and Scattered Disk populations using a procedure that introduces observational bias to a set of objects in orbits obtained from numerical simulations of the evolution of the Oort cloud and Scattered Disk in the framework of the Nice model. The application of the procedure consistently determines that the brightest distant Lace (semi-major axis above 500 au) is fainter than the brightest classical Centaur by about one magnitude, no matter what parameters were used for the procedure. However, reality shows a reversed situation: there is an excess of Laces with lower visual magnitudes. It is not clear why this is the case. We test whether a planetary-mass solar companion could produce an excess of bright Laces in comparison with classical Centaurs. We find that with the companion there is an excess of luminous Laces compared to when there is no companion. However, the companion model also produces many classical Centaurs with lower visual magnitudes than the observed ones. Thus we conclude that the companion does not solve this visual magnitude inconsistency, although the results are in general more coherent under the model with the companion than without.

  17. Morphologic observation of mucosa-associated lymphoid tissue in the large intestine of Bactrian camels (Camelus bactrianus).

    PubMed

    ZhaXi, Yingpai; Wang, Wenhui; Zhang, Wangdong; Gao, Qiang; Guo, Minggang; Jia, Shuai

    2014-07-01

    The structure and distribution of the mucosa-associated lymphoid tissue (MALT) throughout the large intestine of 10 Bactrian camels were comparatively studied by anatomical and histological methods. The results showed that Peyer's patches (PPs) were mainly located on the mucosal surfaces of the entire ileocecal orifice, the beginning of the cecum and the first third of the colon. The shape of PPs gradually changed from "scrotiform" to "faviform" along the large intestine with the scrotiform PP as the major type in the ileocecal orifice. The distribution density also gradually decreased from the ileocecal orifice to the colon. The histological observations further revealed that the MALT in the form of PPs or isolated lymphoid follicles (ILF) and lamina propria lymphocytes was mainly present in the lamina propria and submucosa from the entire ileocecal orifice, where the muscularis mucosa is usually incomplete, to the colonic forepart. In addition, lymphoid tissue was much more abundant in the lamina propria and submucosa of the ileocecal orifice as compared to the cecum and colon. Statistically, the MALT of the ileocecal orifice contained a higher number of lymphoid follicles (37.7/10 mm(2) ) than that of the cecum, colon, or rectum (P < 0.05). The germinal centers of the lymphoid follicles were clearly visible. Together, our data suggest that the ileocecal orifice constitutes the main inductive site for the mucosal immunity in the large intestine of the Bactrian camel; and that scrotiform PPs are likely to the result of long-term adaptation of the Bactrian camel to the harsh living environment.

  18. Local SAR, Global SAR, and Power-Constrained Large-Flip-Angle Pulses with Optimal Control and Virtual Observation Points

    PubMed Central

    Vinding, Mads S.; Guérin, Bastien; Vosegaard, Thomas; Nielsen, Niels Chr.

    2016-01-01

    Purpose To present a constrained optimal-control (OC) framework for designing large-flip-angle parallel-transmit (pTx) pulses satisfying hardware peak-power as well as regulatory local and global specific-absorption-rate (SAR) limits. The application is 2D and 3D spatial-selective 90° and 180° pulses. Theory and Methods The OC gradient-ascent-pulse-engineering method with exact gradients and the limited-memory Broyden-Fletcher-Goldfarb-Shanno method is proposed. Local SAR is constrained by the virtual-observation-points method. Two numerical models facilitated the optimizations, a torso at 3 T and a head at 7 T, both in eight-channel pTx coils and acceleration-factors up to 4. Results The proposed approach yielded excellent flip-angle distributions. Enforcing the local-SAR constraint, as opposed to peak power alone, reduced the local SAR 7 and 5-fold with the 2D torso excitation and inversion pulse, respectively. The root-mean-square errors of the magnetization profiles increased less than 5% with the acceleration factor of 4. Conclusion A local and global SAR, and peak-power constrained OC large-flip-angle pTx pulse design was presented, and numerically validated for 2D and 3D spatial-selective 90° and 180° pulses at 3 T and 7 T. PMID:26715084

  19. Evolution of Circular Polarization Ratio (CPR) Profiles of Kilometer-scale Craters on the Lunar Maria

    NASA Technical Reports Server (NTRS)

    King, I. R.; Fassett, C. I.; Thomson, B. J.; Minton, D. A.; Watters, W. A.

    2017-01-01

    When sufficiently large impact craters form on the Moon, rocks and unweathered materials are excavated from beneath the regolith and deposited into their blocky ejecta. This enhances the rockiness and roughness of the proximal ejecta surrounding fresh impact craters. The interior of fresh craters are typically also rough, due to blocks, breccia, and impact melt. Thus, both the interior and proximal ejecta of fresh craters are usually radar bright and have high circular polarization ratios (CPR). Beyond the proximal ejecta, radar-dark halos are observed around some fresh craters, suggesting that distal ejecta is finer-grained than background regolith. The radar signatures of craters fade with time as the regolith grows.

  20. Dark Matter Constraints from Observations of 25 Milky Way Satellite Galaxies with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Albert, A.; Anderson, B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Bouvier, A.; Brandt, T. J.; Hays, E.; Perkins, J. S.

    2013-01-01

    The dwarf spheroidal satellite galaxies of the Milky Way are some of the most dark-matter-dominated objects known. Due to their proximity, high dark matter content, and lack of astrophysical backgrounds, dwarf spheroidal galaxies are widely considered to be among the most promising targets for the indirect detection of dark matter via gamma rays. Here we report on gamma ray observations of 25 Milky Way dwarf spheroidal satellite galaxies based on 4 years of Fermi Large Area Telescope (LAT) data. None of the dwarf galaxies are significantly detected in gamma rays, and we present gamma ray flux upper limits between 500MeV and 500 GeV. We determine the dark matter content of 18 dwarf spheroidal galaxies from stellar kinematic data and combine LAT observations of 15 dwarf galaxies to constrain the dark matter annihilation cross section. We set some of the tightest constraints to date on the annihilation of dark matter particles with masses between 2 GeV and 10TeV into prototypical standard model channels. We find these results to be robust against systematic uncertainties in the LAT instrument performance, diffuse gamma ray background modeling, and assumed dark matter density profile.

  1. Dark matter constraints from observations of 25 Milky Way satellite galaxies with the Fermi Large Area Telescope

    SciTech Connect

    Ackermann, M.; et al.

    2014-02-11

    The dwarf spheroidal satellite galaxies of the Milky Way are some of the most dark-matter-dominated objects known. Due to their proximity, high dark matter content, and lack of astrophysical backgrounds, dwarf spheroidal galaxies are widely considered to be among the most promising targets for the indirect detection of dark matter via gamma rays. Here we report on gamma-ray observations of 25 Milky Way dwarf spheroidal satellite galaxies based on 4 years of Fermi Large Area Telescope (LAT) data. None of the dwarf galaxies are significantly detected in gamma rays, and we present gamma-ray flux upper limits between 500 MeV and 500 GeV. We determine the dark matter content of 18 dwarf spheroidal galaxies from stellar kinematic data and combine LAT observations of 15 dwarf galaxies to constrain the dark matter annihilation cross section. We set some of the tightest constraints to date on the the annihilation of dark matter particles with masses between 2 GeV and 10 TeV into prototypical Standard Model channels. We find these results to be robust against systematic uncertainties in the LAT instrument performance, diffuse gamma-ray background modeling, and assumed dark matter density profile.

  2. Routes towards the experimental observation of the large fluctuations due to chaos-assisted tunneling effects with cold atoms

    NASA Astrophysics Data System (ADS)

    Dubertrand, R.; Billy, J.; Guéry-Odelin, D.; Georgeot, B.; Lemarié, G.

    2016-10-01

    In the presence of a complex classical dynamics associated with a mixed phase space, a quantum wave function can tunnel between two stable islands through the chaotic sea, an effect that has no classical counterpart. This phenomenon, referred to as chaos-assisted tunneling, is characterized by large fluctuations of the tunneling rate when a parameter is varied. To date, the full extent of this effect as well as the associated statistical distribution have never been observed in a quantum system. Here, we analyze the possibility of characterizing these effects accurately in a cold-atom experiment. Using realistic values of the parameters of an experimental setup, we examine through analytical estimates and extensive numerical simulations a specific system that can be implemented with cold atoms, the atomic modulated pendulum. We assess the efficiency of three possible routes to observe in detail chaos-assisted tunneling properties. Our main conclusion is that due to the fragility of the symmetry between positive and negative momenta as a function of quasimomentum, it is very challenging to use tunneling between classical islands centered on fixed points with opposite momentum. We show that it is more promising to use islands symmetric in position space, and characterize the regime where it could be done. The proposed experiment could be realized with current state-of-the-art technology.

  3. Large-amplitude electric fields in the inner magnetosphere: Van Allen Probes observations of subauroral polarization streams

    NASA Astrophysics Data System (ADS)

    Califf, S.; Li, X.; Wolf, R. A.; Zhao, H.; Jaynes, A. N.; Wilder, F. D.; Malaspina, D. M.; Redmon, R.

    2016-06-01

    The subauroral polarization stream (SAPS) is an important magnetosphere-ionosphere (MI) coupling phenomenon that impacts a range of particle populations in the inner magnetosphere. SAPS studies often emphasize ionospheric signatures of fast westward flows, but the equatorial magnetosphere is also affected through strong radial electric fields in the dusk sector. This study focuses on a period of steady southward interplanetary magnetic field (IMF) during the 29 June 2013 geomagnetic storm where the Van Allen Probes observe a region of intense electric fields near the plasmapause over multiple consecutive outbound duskside passes. We show that the large-amplitude electric fields near the equatorial plane are consistent with SAPS by investigating the relationship between plasma sheet ion and electron boundaries, associated field-aligned currents, and the spatial location of the electric fields. By incorporating high-inclination DMSP data we demonstrate the spatial and temporal variability of the SAPS region, and we suggest that discrete, earthward propagating injections are driving the observed strong electric fields at low L shells in the equatorial magnetosphere. We also show the relationship between SAPS and plasmasphere erosion, as well as a possible correlation with flux enhancements for 100s keV electrons.

  4. The VELA-X-Pulsar Wind Nebula Revisited with Four Years of Fermi Large Area Telescope Observations

    NASA Technical Reports Server (NTRS)

    Grondin, M. -H.; Romani, R. W.; Lemoine-Goumard, M.; Guillemot, L.; Harding, Alice K.; Reposeur, T.

    2013-01-01

    The Vela supernova remnant (SNR) is the closest SNR to Earth containing an active pulsar, the Vela pulsar (PSR B0833-45). This pulsar is an archetype of the middle-aged pulsar class and powers a bright pulsar wind nebula (PWN), Vela-X, spanning a region of 2deg × 3deg south of the pulsar and observed in the radio, X-ray, and very high energy ?-ray domains. The detection of the Vela-X PWN by the Fermi Large Area Telescope (LAT) was reported in the first year of the mission. Subsequently, we have reinvestigated this complex region and performed a detailed morphological and spectral analysis of this source using 4 yr of Fermi-LAT observations. This study lowers the threshold for morphological analysis of the nebula from 0.8 GeV to 0.3 GeV, allowing for the inspection of distinct energy bands by the LAT for the first time. We describe the recent results obtained on this PWN and discuss the origin of the newly detected spatial features.

  5. THE VELA-X PULSAR WIND NEBULA REVISITED WITH FOUR YEARS OF FERMI LARGE AREA TELESCOPE OBSERVATIONS

    SciTech Connect

    Grondin, M.-H.; Romani, R. W.; Lemoine-Goumard, M.; Reposeur, T.; Harding, A. K.

    2013-09-10

    The Vela supernova remnant (SNR) is the closest SNR to Earth containing an active pulsar, the Vela pulsar (PSR B0833-45). This pulsar is an archetype of the middle-aged pulsar class and powers a bright pulsar wind nebula (PWN), Vela-X, spanning a region of 2 Degree-Sign Multiplication-Sign 3 Degree-Sign south of the pulsar and observed in the radio, X-ray, and very high energy {gamma}-ray domains. The detection of the Vela-X PWN by the Fermi Large Area Telescope (LAT) was reported in the first year of the mission. Subsequently, we have reinvestigated this complex region and performed a detailed morphological and spectral analysis of this source using 4 yr of Fermi-LAT observations. This study lowers the threshold for morphological analysis of the nebula from 0.8 GeV to 0.3 GeV, allowing for the inspection of distinct energy bands by the LAT for the first time. We describe the recent results obtained on this PWN and discuss the origin of the newly detected spatial features.

  6. A DEEP CHANDRA OBSERVATION OF THE OXYGEN-RICH SUPERNOVA REMNANT 0540-69.3 IN THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Park, Sangwook; Burrows, David N.; Hughes, John P.; Slane, Patrick O.; Mori, Koji

    2010-02-20

    Using our deep {approx}120 ks Chandra observation, we report on the results from our spatially resolved X-ray spectral analysis of the 'oxygen-rich' supernova remnant (SNR) 0540-69.3 in the Large Magellanic Cloud. We conclusively establish the nonthermal nature of the 'arcs' in the east and west boundaries of the SNR, which confirms the cosmic-ray electron acceleration in the supernova shock (B {approx} 20-140 {mu}G). We report tentative evidence for Fe overabundance in the southern region close to the outer boundary of the SNR. While such a detection would be intriguing, the existence of Fe ejecta is not conclusive with the current data because of poor photon statistics and limited plasma models. If it is verified using deeper X-ray observations and improved plasma models, the presence of Fe ejecta, which was produced in the core of the supernova, near the SNR's outer boundary would provide an intriguing opportunity to study the explosive nucleosynthesis and the ejecta mixing in this young core-collapse SNR. There is no evidence of X-ray counterparts for the optical O-rich ejecta in the central regions of the SNR.

  7. Facing the Challenges of Accessing, Managing, and Integrating Large Observational Datasets in Ecology: Enabling and Enriching the Use of NEON's Observational Data

    NASA Astrophysics Data System (ADS)

    Thibault, K. M.

    2013-12-01

    As the construction of NEON and its transition to operations progresses, more and more data will become available to the scientific community, both from NEON directly and from the concomitant growth of existing data repositories. Many of these datasets include ecological observations of a diversity of taxa in both aquatic and terrestrial environments. Although observational data have been collected and used throughout the history of organismal biology, the field has not yet fully developed a culture of data management, documentation, standardization, sharing and discoverability to facilitate the integration and synthesis of datasets. Moreover, the tools required to accomplish these goals, namely database design, implementation, and management, and automation and parallelization of analytical tasks through computational techniques, have not historically been included in biology curricula, at either the undergraduate or graduate levels. To ensure the success of data-generating projects like NEON in advancing organismal ecology and to increase transparency and reproducibility of scientific analyses, an acceleration of the cultural shift to open science practices, the development and adoption of data standards, such as the DarwinCore standard for taxonomic data, and increased training in computational approaches for biologists need to be realized. Here I highlight several initiatives that are intended to increase access to and discoverability of publicly available datasets and equip biologists and other scientists with the skills that are need to manage, integrate, and analyze data from multiple large-scale projects. The EcoData Retriever (ecodataretriever.org) is a tool that downloads publicly available datasets, re-formats the data into an efficient relational database structure, and then automatically imports the data tables onto a user's local drive into the database tool of the user's choice. The automation of these tasks results in nearly instantaneous execution

  8. 77 FR 42077 - Environmental Justice: Final Circular

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-17

    ... TRANSPORTATION Federal Transit Administration Environmental Justice: Final Circular AGENCY: Federal Transit... (hereinafter ``EJ Circular'') on incorporating environmental justice principles into plans, projects, and... recipients of FTA funds on how to fully engage environmental justice populations in the public...

  9. GPS and GLONASS observations of large-scale traveling ionospheric disturbances during the 2015 St. Patrick's Day storm

    NASA Astrophysics Data System (ADS)

    Zakharenkova, Irina; Astafyeva, Elvira; Cherniak, Iurii

    2016-12-01

    Using a comprehensive database of 5300 ground-based Global Navigation Satellite Systems (GNSS) stations we have investigated large-scale traveling ionospheric disturbances (LSTIDs) during 17-18 March 2015 (St. Patrick's Day storm). For the first time, the high-resolution, two-dimensional maps of the total electron content perturbation were made using not only GPS but also GLONASS measurements. Several LSTIDs originated from the auroral regions in the Northern and Southern Hemispheres were observed simultaneously over Europe, North America, and South America. This storm is considered as a two-step main phase storm. During the first main phase LSTIDs propagated over the whole daytime European region and over high latitudes of North America. During the second main phase we report (1) intense LSTIDs propagated equatorward in North America and Europe, (2) convergence of several LSTIDs originated from the opposite hemispheres in the interference zone over geomagnetic equator in South America, and (3) "super" LSTIDs with the wavefront length of more than 10,000 km observed simultaneously in North America and Europe. LSTIDs observed in three sectors had wavelength of 1200-2500 km and wave periods of 50-80 min. During the recovery phase on the background of the negative ionospheric storm developed over North America we detect signatures of the stream-like structures elongated within the latitudinal range of 29°N-42°N across the U.S. These structures persisted through the nighttime to the early morning from 04 UT to 13 UT on 18 March 2015, and they were associated with the subauroral polarization stream-induced nighttime ionospheric flows.

  10. Magnetic Circular Dichroism of X-Ray Emission for Gadolinium in 4d-4f Excitation Region

    NASA Astrophysics Data System (ADS)

    Takayama, Yasuhiro; Shinoda, Motoki; Obu, Kenji; Lee, Chol; Shiozawa, Hidetsugu; Hirose, Masaaki; Ishii, Hiroyoshi; Miyahara, Tsuneaki; Okamoto, Jun

    2002-01-01

    We have measured magnetic circular dichroism of x-ray emission spectra (XES) for gadolinium in the 4d-4f excitation region. At a pre-threshold excitation energy, a large magnetic circular dichroism (MCD) signal appeared in a Raman scattering and the dramatic dependence of the MCD spectra on the excitation energy was observed. Theoretical calculation shows that the magnetic moment estimated with total photoelectron yield (TEY) spectra was much smaller than that with the emission spectra. This indicates that the MCD for the TEY reflects the magnetic state on the surface whereas the MCD for the XES reflects that in the bulk. We also observed the MCD spectra for total photon yield (TPY) and found the great difference of the MCD spectra for the TEY and TPY.

  11. Relaxation Dynamics in Photoexcited Chiral Molecules Studied by Time-Resolved Photoelectron Circular Dichroism: Toward Chiral Femtochemistry

    PubMed Central

    2016-01-01

    Unravelling the main initial dynamics responsible for chiral recognition is a key step in the understanding of many biological processes. However, this challenging task requires a sensitive enantiospecific probe to investigate molecular dynamics on their natural femtosecond time scale. Here we show that, in the gas phase, the ultrafast relaxation dynamics of photoexcited chiral molecules can be tracked by recording time-resolved photoelectron circular dichroism (TR-PECD) resulting from the photoionization by a circularly polarized probe pulse. A large forward–backward asymmetry along the probe propagation axis is observed in the photoelectron angular distribution. Its evolution with pump–probe delay reveals ultrafast dynamics that are inaccessible in the angle-integrated photoelectron spectrum or via the usual electron emission anisotropy parameter (β). PECD, which originates from the electron scattering in the chiral molecular potential, appears as a new sensitive observable for ultrafast molecular dynamics in chiral systems. PMID:27786493

  12. Circular Dichroism in Multiphoton Ionization of Resonantly Excited He+ Ions

    NASA Astrophysics Data System (ADS)

    Ilchen, M.; Douguet, N.; Mazza, T.; Rafipoor, A. J.; Callegari, C.; Finetti, P.; Plekan, O.; Prince, K. C.; Demidovich, A.; Grazioli, C.; Avaldi, L.; Bolognesi, P.; Coreno, M.; Di Fraia, M.; Devetta, M.; Ovcharenko, Y.; Düsterer, S.; Ueda, K.; Bartschat, K.; Grum-Grzhimailo, A. N.; Bozhevolnov, A. V.; Kazansky, A. K.; Kabachnik, N. M.; Meyer, M.

    2017-01-01

    Intense, circularly polarized extreme-ultraviolet and near-infrared (NIR) laser pulses are combined to double ionize atomic helium via the oriented intermediate He+(3 p ) resonance state. Applying angle-resolved electron spectroscopy, we find a large photon helicity dependence of the spectrum and the angular distribution of the electrons ejected from the resonance by NIR multiphoton absorption. The measured circular dichroism is unexpectedly found to vary strongly as a function of the NIR intensity. The experimental data are well described by theoretical modeling and possible mechanisms are discussed.

  13. Development of the Large-Scale Statistical Analysis System of Satellites Observations Data with Grid Datafarm Architecture

    NASA Astrophysics Data System (ADS)

    Yamamoto, K.; Murata, K.; Kimura, E.; Honda, R.

    2006-12-01

    In the Solar-Terrestrial Physics (STP) field, the amount of satellite observation data has been increasing every year. It is necessary to solve the following three problems to achieve large-scale statistical analyses of plenty of data. (i) More CPU power and larger memory and disk size are required. However, total powers of personal computers are not enough to analyze such amount of data. Super-computers provide a high performance CPU and rich memory area, but they are usually separated from the Internet or connected only for the purpose of programming or data file transfer. (ii) Most of the observation data files are managed at distributed data sites over the Internet. Users have to know where the data files are located. (iii) Since no common data format in the STP field is available now, users have to prepare reading program for each data by themselves. To overcome the problems (i) and (ii), we constructed a parallel and distributed data analysis environment based on the Gfarm reference implementation of the Grid Datafarm architecture. The Gfarm shares both computational resources and perform parallel distributed processings. In addition, the Gfarm provides the Gfarm filesystem which can be as virtual directory tree among nodes. The Gfarm environment is composed of three parts; a metadata server to manage distributed files information, filesystem nodes to provide computational resources and a client to throw a job into metadata server and manages data processing schedulings. In the present study, both data files and data processes are parallelized on the Gfarm with 6 file system nodes: CPU clock frequency of each node is Pentium V 1GHz, 256MB memory and40GB disk. To evaluate performances of the present Gfarm system, we scanned plenty of data files, the size of which is about 300MB for each, in three processing methods: sequential processing in one node, sequential processing by each node and parallel processing by each node. As a result, in comparison between the

  14. Large grains in discs around young stars: ATCA observations of WW Chamaeleontis, RU Lupi, and CS Chamaeleontis

    NASA Astrophysics Data System (ADS)

    Lommen, D.; Maddison, S. T.; Wright, C. M.; van Dishoeck, E. F.; Wilner, D. J.; Bourke, T. L.

    2009-03-01

    Context: Grains in discs around young stars grow from interstellar submicron sizes to planetesimals, up to thousands of kilometres in size, over the course of several Myr. Thermal emission of large grains or pebbles can be best observed at centimetre wavelengths. However, other emission mechanisms can contribute, most notably free-free emission from stellar winds and chromospheric activity. Aims: We aim to determine the mechanisms of centimetre emission for three T Tauri stars. WW Cha and RU Lup have recently been found to have grain growth at least up to millimetre sizes in their circumstellar discs, based on millimetre data up to 3.3 mm. CS Cha has similar indications of grain growth in its circumbinary disc. Methods: The T Tauri stars WW Cha and RU Lup were monitored over the course of several years at millimetre and centimetre wavelengths, using the Australia Telescope Compact Array (ATCA). The new ATCA 7 mm system was also used to observe CS Cha at 7 mm. Results: WW Cha was detected on several occasions at 7 and 16 mm. We obtained one detection of WW Cha at 3.5 cm and upper limits only for 6.3 cm. The emission at 16 mm was stable over periods of days, months, and years, whereas the emission at 3.5 cm is found to be variable. A second young stellar object, Ced 112 IRS 4, was found in the field of WW Cha at 16 mm. RU Lup was detected at 7 mm. It was observed at 16 mm three times and at 3 and 6 cm four times and found to be variable in all three wavebands. CS Cha was detected at 7 mm, but the signal-to-noise ratio was not high enough to resolve the gap in the circumbinary disc. The typical resolution of the 7 and 16 mm observations was 5-10 arcsec with rms ~0.2 mJy. Conclusions: The emission at 3, 7, and 16 mm for WW Cha is explained well by thermal emission from millimetre and centimetre-sized “pebbles”. The cm spectral index between 3.5 and 6.3 cm is consistent with the emission from an optically-thick ionised wind, although the high variability of the cm

  15. Experimental Realization of Efficient, Room Temperature Single-Photon Sources with Definite Circular and Linear Polarizations

    NASA Astrophysics Data System (ADS)

    Boutsidis, Christos

    In this thesis I present experimental demonstrations of room-temperature, single-photon sources with definite linear and circular polarizations. Definite photon polarization increases the efficiency of quantum communication systems. In contrast with cryogenic-temperature single-photon sources based on epitaxial quantum dots requiring expensive MBE and nanofabrication, my method utilizes a mature liquid crystal technology, which I made consistent with single-emitter fluorescence microscopy. The structures I have prepared are planar-aligned cholesteric liquid crystals forming 1-D photonic bandgaps for circularly-polarized light, which were used to achieve definite circularly-polarized fluorescence of single emitters doped in this environment. I also used planar-aligned nematic liquid crystals to align single molecules with linear dipole moments and achieved definite linearly-polarized fluorescence. I used single nanocrystal quantum dots, single nanodiamond color-centers, rare-earth-doped nanocrystals, and single terrylene and DiIC18(3) dye molecules as emitters. For nanocrystal quantum dots I observed circular polarization dissymmetry factors as large as ge = --1.6. In addition, I observed circularly-polarized resonances in the fluorescence of emitters within a cholesteric microcavity, with cavity quality factors of up to Q ˜ 250. I also showed that the fluorescence of DiIC18(3) dye molecules in planar-aligned nematic cells exhibits definite linear polarization, with a degree of polarization of rho = --0.58 +/- 0.03. Distributed Bragg reflectors form another type of microcavity that can be used to realize a single-photon source. I characterized the fluorescence from nanocrystal quantum dots doped in the defect layers of such microcavites, both organic and inorganic. Finally, to demonstrate the single-photon properties of single-emitter-doped cholesteric and nematic liquid crystal structures and distributed Bragg reflector microcavities, I present observations of

  16. Large-scale atmospheric circulation and local particulate matter concentrations in Bavaria - from current observations to future projections

    NASA Astrophysics Data System (ADS)

    Beck, Christoph; Weitnauer, Claudia; Brosy, Caroline; Hald, Cornelius; Lochbihler, Kai; Siegmund, Stefan; Jacobeit, Jucundus

    2016-04-01

    Particulate matter with an aerodynamic diameter of 10 μm or less (PM10) may have distinct adverse effects on human health. Spatial and temporal variations in PM10 concentrations reflect local emission rates, but are as well influenced by the local and synoptic-scale atmospheric conditions. Against this background, it can be furthermore argued that potential future climate change and associated variations in large-scale atmospheric circulation and local meteorological parameters will probably provoke corresponding changes in future PM10 concentration levels. The DFG-funded research project „Particulate matter and climate change in Bavaria" aimed at establishing quantitative relationships between daily and monthly PM10 indices at different Bavarian urban stations and the corresponding large-scale atmospheric circulation as well as local meteorological conditions. To this end, several statistical downscaling approaches have been developed for the period 1980 to 2011. PM10 data from 19 stations from the air quality monitoring network (LÜB) of the Bavarian Environmental Agency (LfU) have been utilized as predictands. Large-scale atmospheric gridded data from the NCEP/NCAR reanalysis data base and local meteorological observational data provided by the German Meteorological Service (DWD) served as predictors. The downscaling approaches encompass the synoptic downscaling of daily PM10 concentrations and several multivariate statistical models for the estimation of daily and monthly PM10, i.e.monthly mean and number of days exceeding a certain PM10 concentration threshold. Both techniques utilize objective circulation type classifications, which have been optimized with respect to their synoptic skill for the target variable PM10. All downscaling approaches have been evaluated via cross validation using varying subintervals of the 1980-2011 period as calibration and validation periods respectively. The most suitable - in terms of model skill determined from cross

  17. Circular on planned parenthood, 1987.

    PubMed

    1987-01-01

    In 1987 fourteen units of the Government of Henan issued a Circular stating that: "Planned parenthood must be publicized deep into the grass roots and among the people, and importance must be attached to results." The Circular stresses: "In the propaganda drive, it is necessary to successfully grasp three key links: 1. It is necessary to disseminate intensively the important directive on population problems that is contained in the report of the 13th CPC National Congress and the seriousness of the population situation of our country and province so that the cadres and the masses can understand the relationship between population control and the achievement of the strategic target of the three big steps, understand the reason for carrying out planned parenthood, understand that the one-child policy is still advocated, and conscientiously carry out planned parenthood. 2. It is essential to succeed in propagating knowledge of contraception, sterilization, childbirth, and child care and in conducting ideological education for those who undergo operations and for their family members. 3. It is imperative to visit those who have undergone operations and to help them solve practically their difficulties in making a living." The Circular concludes by demanding that under the unified leadership of party committees and governments at all levels, the propaganda drive be carried out by relying on the efforts of all of society. In conjunction with their own work, departments, including the propaganda, education, public health, and cultural departments, must carry out propaganda and education for planned parenthood.

  18. A novel replicating circular DNAzyme

    PubMed Central

    Chen, Fei; Wang, Ruijian; Li, Zhe; Liu, Bin; Wang, Xiaoping; Sun, Yanhong; Hao, Dongyun; Zhang, Jin

    2004-01-01

    10–23 DNAzyme has the potential to suppress gene expressions through sequence-specific mRNA cleavage. However, the dependence on exogenous delivery limits its applications. The objective of this work is to establish a replicating DNAzyme in bacteria using a single-stranded DNA vector. By cloning the 10–23 DNAzyme into the M13mp18 vector, we constructed two circular DNAzymes, C-Dz7 and C-Dz482, targeting the β-lactamase mRNA. These circular DNAzymes showed in vitro catalytic efficiencies (kcat/KM) of 7.82 × 106 and 1.36 × 107 M–1·min–1, respectively. Their dependence on divalent metal ions is similar to that found with linear 10–23 DNAzyme. Importantly, the circular DNAzymes were not only capable of replicating in bacteria but also exhibited high activities in inhibiting β-lactamase and bacterial growth. This study thus provides a novel strategy to produce replicating DNAzymes which may find widespread applications. PMID:15115797

  19. On electrostatically actuated NEMS/MEMS circular plates

    NASA Astrophysics Data System (ADS)

    Caruntu, Dumitru I.; Alvarado, Iris

    2011-04-01

    This paper deals with electrostatically actuated micro and nano-electromechanical (MEMS/NEMS) circular plates. The system under investigation consists of two bodies, a deformable and conductive circular plate placed above a fixed, rigid and conductive ground plate. The deformable circular plate is electrostatically actuated by applying an AC voltage between the two plates. Nonlinear parametric resonance and pull-in occur at certain frequencies and relatively large AC voltage, respectively. Such phenomena are useful for applications such as sensors, actuators, switches, micro-pumps, micro-tweezers, chemical and mass sensing, and micro-mirrors. A mathematical model of clamped circular MEMS/NEMS electrostatically actuated plates has been developed. Since the model is in the micro- and nano-scale, surface forces, van der Waals and/or Casimir, acting on the plate are included. A perturbation method, the Method of Multiple Scales (MMS), is used for investigating the case of weakly nonlinear MEMS/NEMS circular plates. Two time scales, fast and slow, are considered in this work. The amplitude-frequency and phase-frequency response of the plate in the case of primary resonance are obtained and discussed.

  20. Chirped microlens arrays for diode laser circularization and beam expansion

    NASA Astrophysics Data System (ADS)

    Schreiber, Peter; Dannberg, Peter; Hoefer, Bernd; Beckert, Erik

    2005-08-01

    Single-mode diode lasers are well-established light sources for a huge number of applications but suffer from astigmatism, beam ellipticity and large manufacturing tolerances of beam parameters. To compensate for these shortcomings, various approaches like anamorphic prism pairs and cylindrical telescopes for circularization as well as variable beam expanders based on zoomed telescopes for precise adjustment of output beam parameters have been employed in the past. The presented new approach for both beam circularization and expansion is based on the use of microlens arrays with chirped focal length: Selection of lenslets of crossed cylindrical microlens arrays as part of an anamorphic telescope enables circularization, astigmatism correction and divergence tolerance compensation of diode lasers simultaneously. Another promising application of chirped spherical lens array telescopes is stepwise variable beam expansion for circular laser beams of fiber or solid-state lasers. In this article we describe design and manufacturing of beam shaping systems with chirped microlens arrays fabricated by polymer-on-glass replication of reflow lenses. A miniaturized diode laser module with beam circularization and astigmatism correction assembled on a structured ceramics motherboard and a modulated RGB laser-source for photofinishing applications equipped with both cylindrical and spherical chirped lens arrays demonstrate the feasibility of the proposed system design approach.

  1. Deep 3-GHz observations of the Lockman Hole North with the Very Large Array - I. Source extraction and uncertainty analysis

    NASA Astrophysics Data System (ADS)

    Vernstrom, T.; Scott, Douglas; Wall, J. V.; Condon, J. J.; Cotton, W. D.; Perley, R. A.

    2016-09-01

    This is the first of two papers describing the observations and cataloguing of deep 3-GHz observations of the Lockman Hole North using the Karl G. Jansky Very Large Array. The aim of this paper is to investigate, through the use of simulated images, the uncertainties and accuracy of source-finding routines, as well as to quantify systematic effects due to resolution, such as source confusion and source size. While these effects are not new, this work is intended as a particular case study that can be scaled and translated to other surveys. We use the simulations to derive uncertainties in the fitted parameters, as well as bias corrections for the actual catalogue (presented in Paper II). We compare two different source-finding routines, OBIT and AEGEAN, and two different effective resolutions, 8 and 2.75 arcsec. We find that the two routines perform comparably well, with OBIT being slightly better at de-blending sources, but slightly worse at fitting resolved sources. We show that 30-70 per cent of sources are missed or fit inaccurately once the source size becomes larger than the beam, possibly explaining source count errors in high-resolution surveys. We also investigate the effect of blending, finding that any sources with separations smaller than the beam size are fit as single sources. We show that the use of machine-learning techniques can correctly identify blended sources up to 90 per cent of the time, and prior-driven fitting can lead to a 70 per cent improvement in the number of de-blended sources.

  2. Circular polarization by scattering from spheroidal dust grains

    NASA Astrophysics Data System (ADS)

    Gledhill, T. M.; McCall, A.

    2000-05-01

    Large degrees of circular polarization at near-infrared wavelengths have been reported in the OMC1 star-forming region. This discovery, in combination with compelling evidence for the existence of non-spherical aligned grains in star formation regions, has prompted us to investigate scattering from spheroidal particles as a possible mechanism for the production of large circular polarization in reflection nebulae. We use a dipole calculation to model the small particle limit and a T-matrix code to treat arbitrarily sized particles. We find that size distributions of perfectly aligned spheroids, with only modest 2:1 axis ratios, are capable of producing circular polarization of up to 50 per cent when scattering unpolarized incident light. This is the case even for dielectric materials, such as `astronomical silicate', as long as sufficient large particles are included in the size distribution. We consider the effects of particle alignment and find that spinning oblate spheroids should be much more efficient circular polarizers than equivalent prolate spheroids.

  3. Circularization of tidally disrupted stars around spinning supermassive black holes

    NASA Astrophysics Data System (ADS)

    Hayasaki, Kimitake; Stone, Nicholas; Loeb, Abraham

    2016-10-01

    We study the circularization of tidally disrupted stars on bound orbits around spinning supermassive black holes by performing 3D smoothed particle hydrodynamic simulations with post-Newtonian corrections. Our simulations reveal that debris circularization depends sensitively on the efficiency of radiative cooling. There are two stages in debris circularization if radiative cooling is inefficient: first, the stellar debris streams self-intersect due to relativistic apsidal precession; shocks at the intersection points thermalize orbital energy and the debris forms a geometrically thick, ring-like structure around the black hole. The ring rapidly spreads via viscous diffusion, leading to the formation of a geometrically thick accretion disc. In contrast, if radiative cooling is efficient, the stellar debris circularizes due to self-intersection shocks and forms a geometrically thin ring-like structure. In this case, the dissipated energy can be emitted during debris circularization as a precursor to the subsequent tidal disruption flare. The circularization time-scale is remarkably long in the radiatively efficient cooling case, and is also sensitive to black hole spin. Specifically, Lense-Thirring torques cause dynamically important nodal precession, which significantly delays debris circularization. On the other hand, nodal precession is too slow to produce observable signatures in the radiatively inefficient case. Since the stellar debris is optically thick and its photon diffusion time is likely longer than the time-scale of shock heating, our inefficient cooling scenario is more generally applicable in eccentric tidal disruption events (TDEs). However, in parabolic TDEs for MBH ≳ 2 × 106 M⊙, the spin-sensitive behaviour associated with efficient cooling may be realized.

  4. Fermi-Large Area Telescope Observations of the Exceptional Gamma-Ray Flare from 3C 279 in 2015 June

    NASA Astrophysics Data System (ADS)

    Paliya, Vaidehi S.

    2015-08-01

    An exceptional γ-ray outburst from 3C 279 was detected by the Fermi-Large Area Telescope (LAT) in 2015 June. In the energy range of 0.1-300 GeV, the highest flux measured is (39.1 ± 2.5) × 10-6 {ph} {{cm}}-2 {{{s}}}-1, which is the highest γ-ray flux ever detected from 3C 279, exceeding the previous historically brightest flare observed by EGRET in 1996. The high activity period consists of three major flares with the last one being the brightest. All but one flare show a faster rise and slower decay pattern, and at the peak of the activity, the γ-ray spectrum is found to show a clear signature of break/curvature. The obtained spectral parameters hint that the peak of the inverse Compton emission lies in the LAT energy range (around ˜1 GeV), which is in contrast to that seen during the 2013 December and 2014 April γ-ray flares of 3C 279. From the γγ pair opacity arguments, the minimum Doppler factor is estimated to be 14, and the location of the γ-ray emitting region is found to be either at the outer edge of the broad line region or farther out from it.

  5. Hubble Space Telescope and Very Large Array Observations of the H2O Gigamaser Galaxy TXS 2226-184.

    PubMed

    Falcke; Wilson; Henkel; Brunthaler; Braatz

    2000-02-10

    We present Hubble Space Telescope/Wide-Field and Planetary Camera 2 images in Halpha + [N ii] lambdalambda6548, 6583 lines and continuum radiation and a VLA map at 8 GHz of the H2O gigamaser galaxy TXS 2226-184. This galaxy has the most luminous H2O maser emission known to date. Our red continuum images reveal a highly elongated galaxy with a dust lane crossing the nucleus. The surface brightness profile is best fitted by a bulge plus exponential disk model, favoring classification as a highly inclined spiral galaxy (i=70&j0;). The color map confirms that the dust lane is aligned with the galaxy major axis and is crossing the putative nucleus. The Halpha + [N ii] map exhibits a gaseous, jetlike structure perpendicular to the nuclear dust lane and the galaxy major axis. The radio map shows compact, steep spectrum emission that is elongated in the same direction as the Halpha + [N ii] emission. By analogy with Seyfert galaxies, we therefore suspect that this alignment reflects an interaction between the radio jet and the interstellar medium. The axes of the nuclear dust disk, the radio emission, and the optical line emission apparently define the axis of the active galactic nucleus. The observations suggest that in this galaxy the nuclear accretion disk, obscuring torus, and large-scale molecular gas layer are roughly coplanar. Our classification of the host galaxy strengthens the trend for megamasers to be found preferentially in highly inclined spiral galaxies.

  6. Inferred Cosmic-Ray Spectrum from Fermi Large Area Telescope γ-Ray Observations of Earth’s Limb

    SciTech Connect

    Ackermann, M.; et al.

    2014-04-17

    Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly-discovered features may offer a clue to the origin of high-energy CRs. We use the ${\\it Fermi}$ Large Area Telescope observations of the $\\gamma$-ray emission from the Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range $\\sim 90~$GeV-$6~$TeV (derived from a photon energy range $15~$GeV-$1~$TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index $2.68 \\pm 0.04$ and $2.61 \\pm 0.08$ above $\\sim 200~$GeV, respectively.

  7. Gamma-Ray Observations of the Supernova Remnant RX J0852.0-4622 with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Tanaka, T.; Allafort, A.; Ballet, J.; Funk, S.; Giordano, F.; Hewitt, J.; Lemoine-Goumard, M.; Tajima, H.; Tibolla, O.; Uchiyama, Y.

    2011-01-01

    We report on gamma-ray observations of the supernova remnant (SNR) RX J0852.04622 with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. In the Fermi-LAT data, we find a spatially extended source at the location of the SNR. The extension is consistent with the SNR size seen in other wavelengths such as X-rays and TeV gamma rays, leading to the identification of the gamma-ray source with the SNR. The spectrum is well described as a power law with a photon index of = 1.85 0.06 (stat)+0.18 0.19 (sys), which smoothly connects to the H.E.S.S. spectrum in the TeV energy band. We discuss the gamma-ray emission mechanism based on multiwavelength data. The broadband data can be fit well by a model in which the gamma rays are of hadronic origin. We also consider a scenario with inverse Compton scattering of electrons as the emission mechanism of the gamma rays. Although the leptonic model predicts a harder spectrum in the Fermi-LAT energy range, the model can fit the data considering the statistical and systematic errors.

  8. Inferred Cosmic-Ray Spectrum from Fermi Large Area Telescope γ-Ray Observations of Earth's Limb

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Bottacini, E.; Bouvier, A.; Brandt, T. J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cecchi, C.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; Dalton, M.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Digel, S. W.; Di Venere, L.; do Couto e Silva, E.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Gomez-Vargas, G. A.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hayashi, K.; Hewitt, J. W.; Horan, D.; Hou, X.; Hughes, R. E.; Inoue, Y.; Jackson, M. S.; Jogler, T.; Jóhannesson, G.; Johnson, A. S.; Kamae, T.; Kawano, T.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Mehault, J.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nemmen, R.; Nuss, E.; Ohsugi, T.; Okumura, A.; 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.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Ritz, S.; Roth, M.; Schaal, M.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Strong, A. W.; Takahashi, H.; Takeuchi, Y.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Tronconi, V.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Werner, M.; Winer, B. L.; Wood, K. S.; Wood, M.; Yang, Z.; Fermi LAT Collaboration

    2014-04-01

    Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly discovered features may offer a clue to the origin of high-energy CRs. We use the Fermi Large Area Telescope observations of the γ-ray emission from Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range ˜90 GeV-6 TeV (derived from a photon energy range 15 GeV-1 TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index 2.68±0.04 and 2.61±0.08 above ˜200 GeV, respectively.

  9. OBSERVATIONS OF THE YOUNG SUPERNOVA REMNANT RX J1713.7-3946 WITH THE FERMI LARGE AREA TELESCOPE

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Ballet, J.; Baring, M. G.; Bastieri, D.; Bonamente, E.; Bouvier, A.; Brandt, T. J.; Brigida, M.; Bruel, P. E-mail: funk@slac.stanford.edu

    2011-06-10

    We present observations of the young supernova remnant (SNR) RX J1713.7-3946 with the Fermi Large Area Telescope (LAT). We clearly detect a source positionally coincident with the SNR. The source is extended with a best-fit extension of 0.{sup 0}55 {+-} 0.{sup 0}04 matching the size of the non-thermal X-ray and TeV gamma-ray emission from the remnant. The positional coincidence and the matching extended emission allow us to identify the LAT source with SNR RX J1713.7-3946. The spectrum of the source can be described by a very hard power law with a photon index of {Gamma} = 1.5 {+-} 0.1 that coincides in normalization with the steeper H.E.S.S.-detected gamma-ray spectrum at higher energies. The broadband gamma-ray emission is consistent with a leptonic origin as the dominant mechanism for the gamma-ray emission.

  10. Polarimetric Imaging of Large Cavity Structures in the Pre-transitional Protoplanetary Disk around PDS 70: Observations of the Disk

    NASA Technical Reports Server (NTRS)

    Hashimoto, J.; Hayashi, M.; Iye, M.; Kandori, R.; Kusakabe,N.; Morino, J.-I.; Suto, H.; Suzuki, R.; Tamura, M.; Serabyn, G.; McElwain, M. W.; Dong, R.; Zhu, Z.; Brandt, T.; Janson, M.; Knapp G.; Turner, E. L.

    2012-01-01

    We present high resolution H-band polarized intensity (PI; FWHM = 0."1: 14 AU) and L'-band imaging data (FWHM = 0."11: 15 AU) of the circumstellar disk around the weak-lined T Tauri star PDS 70 in Centaurus at a radial distance of 28 AU (0."2) up to 210 AU (1."5). In both images, a giant inner gap is clearly resolvro for the first time, and the radius of the gap is approx 70 AU. Our data show that the geometric center of the disk shifts by approx 6 AU toward the minor axis. We confirm that the brown dwarf companion candidate to the north of PDS 70 is a background star based on its proper motion. As a result of SED fitting by Monte Carlo radiative transfer modeling, we infer the existence of an optically thick inner disk at a few AU. Combining our observations and modeling, we classify the disk of PDS 70 as a pre-transitional disk. Furthermore, based on the analysis of L'-band imaging data, we put an upper limit mass of companions at approx 30 to approx 50M(sub J) within the gap. Taking account of the presence of the large and sharp gap, we suggest that the gap could be formed by dynamical interactions of sub-stellar companions or multiple unseen giant planets in the gap.

  11. Polarimetric Imaging of Large Cavity Structures in the Pre-transitional Protoplanetary Disk Around PDS 70: Observations of the Disk

    NASA Technical Reports Server (NTRS)

    Hashimoto, J.; Dong, R.; Kudo, T.; Honda, M.; Zhu, Z.; McClure, M. K.; Muto, T.; Wisniewski, J.; Abe, L.; Brandner, W.; Brandt, T.; Carson, J.; Egner, S.; Feldt, M.; Fukagawa, M.; Goto, M.; Grady, C. A.; Guyon, O.; Hayano, Y.; Hayashi, M.; Hayashi, S.; Henning, T.; Hodapp, K.; Ishii, M.; Iye, M.; Janson, M.; Kandori, R.; Knapp, G.; Kusakabe, N.; Kuzuhara, M.; Kwon, J.; Matsuo, T.; Mayama, S.; McElwain, M. W.; Serabyn, G.

    2012-01-01

    We present high resolution H-band polarized intensity (PI; FWHM = 0."1: 14 AU) and L'-band imaging data (FWHM = 0."11: 15 AU) of the circumstellar disk around the weak-lined T Tauri star PDS 70 in Centaurus at a radial distance of 28 AU (0."2) up to 210 AU (1."5). In both images, a giant inner gap is clearly resolved for the first time, and the radius of the gap is approx.70 AU. Our data show that the geometric center of the disk shifts by approx.6 AU toward the minor axis. We confirm that the brown dwarf companion candidate to the north of PDS 70 is a background star based on its proper motion. As a result of SED fitting by Monte Carlo radiative transfer modeling, we infer the existence of an optically thick inner disk at a few AU. Combining our observations and modeling, we classify the disk of PDS 70 as a pre-transitional disk. Furthermore, based on the analysis of L'-band imaging data, we put an upper limit mass of companions at approx.30 to approx.50MJ within the gap. Taking account of the presence of the large and sharp gap, we suggest that the gap could be formed by dynamical interactions of sub-stellar companions or multiple unseen giant planets in the gap. Subject headings: planetary systems - protoplanetary disks - stars: individual (PDS 70) - stars: pre-main sequence - polarization

  12. Inferred cosmic-ray spectrum from Fermi large area telescope γ-ray observations of Earth's limb.

    PubMed

    Ackermann, M; Ajello, M; Albert, A; Allafort, A; Baldini, L; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Blandford, R D; Bloom, E D; Bonamente, E; Bottacini, E; Bouvier, A; Brandt, T J; Brigida, M; Bruel, P; Buehler, R; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Cecchi, C; Charles, E; Chaves, R C G; Chekhtman, A; Chiang, J; Chiaro, G; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Cutini, S; Dalton, M; D'Ammando, F; de Angelis, A; de Palma, F; Dermer, C D; Digel, S W; Di Venere, L; do Couto e Silva, E; Drell, P S; Drlica-Wagner, A; Favuzzi, C; Fegan, S J; Ferrara, E C; Focke, W B; Franckowiak, A; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Gomez-Vargas, G A; Grenier, I A; Grove, J E; Guiriec, S; Gustafsson, M; Hadasch, D; Hanabata, Y; Harding, A K; Hayashida, M; Hayashi, K; Hewitt, J W; Horan, D; Hou, X; Hughes, R E; Inoue, Y; Jackson, M S; Jogler, T; Jóhannesson, G; Johnson, A S; Kamae, T; Kawano, T; Knödlseder, J; Kuss, M; Lande, J; Larsson, S; Latronico, L; Longo, F; Loparco, F; Lovellette, M N; Lubrano, P; Mayer, M; Mazziotta, M N; McEnery, J E; Mehault, J; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nemmen, R; Nuss, E; Ohsugi, T; Okumura, A; 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; Rainò, S; Rando, R; Razzano, M; Razzaque, S; Reimer, A; Reimer, O; Ritz, S; Roth, M; Schaal, M; Schulz, A; Sgrò, C; Siskind, E J; Spandre, G; Spinelli, P; Strong, A W; Takahashi, H; Takeuchi, Y; Thayer, J G; Thayer, J B; Thompson, D J; Tibaldo, L; Tinivella, M; Torres, D F; Tosti, G; Troja, E; Tronconi, V; Usher, T L; Vandenbroucke, J; Vasileiou, V; Vianello, G; Vitale, V; Werner, M; Winer, B L; Wood, K S; Wood, M; Yang, Z

    2014-04-18

    Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly discovered features may offer a clue to the origin of high-energy CRs. We use the Fermi Large Area Telescope observations of the γ-ray emission from Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range ∼90  GeV-6  TeV (derived from a photon energy range 15 GeV-1 TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index 2.68±0.04 and 2.61±0.08 above ∼200  GeV, respectively.

  13. CASE STUDY OF FOUR HOMOLOGOUS LARGE-SCALE CORONAL WAVES OBSERVED ON 2010 APRIL 28 AND 29

    SciTech Connect

    Kienreich, I. W.; Veronig, A. M.; Muhr, N.; Temmer, M.; Vrsnak, B.; Nitta, N.

    2011-02-01

    On 2010 April 28 and 29, the Solar TErrestrial Relations Observatory B/Extreme Ultraviolet Imager observed four homologous large-scale coronal waves, the so-called EIT-waves, within 8 hr. All waves emerged from the same source active region, were accompanied by weak flares and faint coronal mass ejections, and propagated into the same direction at constant velocities in the range of {approx}220-340 km s{sup -1}. The last of these four coronal wave events was the strongest and fastest, with a velocity of 337 {+-} 31 km s{sup -1} and a peak perturbation amplitude of {approx}1.24, corresponding to a magnetosonic Mach number of M{sub ms} {approx} 1.09. The magnetosonic Mach numbers and velocities of the four waves are distinctly correlated, suggestive of the nonlinear fast-mode magnetosonic wave nature of the events. We also found a correlation between the magnetic energy buildup times and the velocity and magnetosonic Mach number.

  14. Observations of M31 and M33 with the Fermi Large Area Telescope: A Galactic Center Excess in Andromeda?

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, M.; Albert, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Cameron, R. A.; Caputo, R.; Caragiulo, M.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiaro, G.; Ciprini, S.; Costanza, F.; Cutini, S.; D’Ammando, F.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Favuzzi, C.; Funk, S.; Fusco, P.; Gargano, F.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Green, D.; Grenier, I. A.; Guillemot, L.; Guiriec, S.; Hayashi, K.; Hou, X.; Jóhannesson, G.; Kamae, T.; Knödlseder, J.; Kong, A. K. H.; Kuss, M.; La Mura, G.; Larsson, S.; Latronico, L.; Li, J.; Longo, F.; Loparco, F.; Lubrano, P.; Maldera, S.; Malyshev, D.; Manfreda, A.; Martin, P.; Mazziotta, M. N.; Michelson, P. F.; Mirabal, N.; Mitthumsiri, W.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Negro, M.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Persic, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Principe, G.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, O.; Sánchez-Conde, M.; Sgrò, C.; Simone, D.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Tanaka, K.; Tibaldo, L.; Torres, D. F.; Troja, E.; Uchiyama, Y.; Wang, J. C.; Wood, K. S.; Wood, M.; Zaharijas, G.; Zhou, M.

    2017-02-01

    The Fermi Large Area Telescope (LAT) has opened the way for comparative studies of cosmic rays (CRs) and high-energy objects in the Milky Way (MW) and in other, external, star-forming galaxies. Using 2 yr of observations with the Fermi LAT, Local Group galaxy M31 was detected as a marginally extended gamma-ray source, while only an upper limit has been derived for the other nearby galaxy M33. We revisited the gamma-ray emission in the direction of M31 and M33 using more than 7 yr of LAT Pass 8 data in the energy range 0.1{--}100 {GeV}, presenting detailed morphological and spectral analyses. M33 remains undetected, and we computed an upper limit of 2.0× {10}-12 {erg} {{cm}}-2 {{{s}}}-1 on the 0.1{--}100 {GeV} energy flux (95% confidence level). This revised upper limit remains consistent with the observed correlation between gamma-ray luminosity and star formation rate tracers and implies an average CR density in M33 that is at most half of that of the MW. M31 is detected with a significance of nearly 10σ . Its spectrum is consistent with a power law with photon index {{Γ }}=2.4+/- {0.1}{stat+{syst}} and a 0.1{--}100 {GeV} energy flux of (5.6+/- {0.6}{stat+{syst}})× {10}-12 {erg} {{cm}}-2 {{{s}}}-1. M31 is detected to be extended with a 4σ significance. The spatial distribution of the emission is consistent with a uniform-brightness disk with a radius of 0.°4 and no offset from the center of the galaxy, but nonuniform intensity distributions cannot be excluded. The flux from M31 appears confined to the inner regions of the galaxy and does not fill the disk of the galaxy or extend far from it. The gamma-ray signal is not correlated with regions rich in gas or star formation activity, which suggests that the emission is not interstellar in origin, unless the energetic particles radiating in gamma rays do not originate in recent star formation. Alternative and nonexclusive interpretations are that the emission results from a population of millisecond pulsars

  15. Harmonic generation by circularly polarized laser beams propagating in plasma

    SciTech Connect

    Agrawal, Ekta; Hemlata,; Jha, Pallavi

    2015-04-15

    An analytical theory is developed for studying the phenomenon of generation of harmonics by the propagation of an obliquely incident, circularly polarized laser beam in homogeneous, underdense plasma. The amplitudes of second and third harmonic radiation as well as detuning distance have been obtained and their variation with the angle of incidence is analyzed. The amplitude of harmonic radiation increases with the angle of incidence while the detuning distance decreases, for a given plasma electron density. It is observed that the generated second and third harmonic radiation is linearly and elliptically polarized, respectively. The harmonic radiation vanishes at normal incidence of the circularly polarized laser beam.

  16. Observations of large-amplitude cross-shore internal bores near the shelf break, Santa Monica Bay, CA

    USGS Publications Warehouse

    Noble, M.A.; Xu, J. P.

    2003-01-01

    Two sets of moorings were deployed along a cross-shelf transect in central Santa Monica bay for four months in the winter of 1998-1999. Both sites had an array of instruments attached to tripods set on the seafloor to monitor currents over the entire water column, surface waves, near-bed temperature, water clarity and suspended sediment. A companion mooring had temperature sensors spaced approximately 10 m apart to measure temperature profiles between the surface and the seafloor. One array was deployed in 70 m of water at a site adjacent to the shelf break, just northwest of a major ocean outfall. The other was deployed on the mid shelf in 35 m of water approximately 6 km from the shelf break site. The subtidal currents in the region flowed parallel to the isobaths with fluctuating time scales around 10 days, a typical coastal-ocean pattern. However, during the falling phase of the barotropic spring tide, sets of large-amplitude, sheared cross-shore current pulses with a duration of 2-5 h were observed at the shelf break site. Currents in these pulses flowed exclusively offshore in a thin layer near the bed with amplitudes reaching 30-40 cm/s. Simultaneously, currents with amplitudes around 15-20 cm/s flowed exclusively onshore in the thicker layer between the offshore flow layer and the sea surface. The net offshore transport was about half the onshore transport. Near-surface isotherms were depressed 30-40 m. These pulses were likely internal bores generated by tidal currents. Bed stresses associated with these events exceeded 3 dynes/cm2. These amplitudes are large enough to resuspend and transport not only fine-grained material, but also medium to coarse sands from the shelf toward the slope. Consequently, the seafloor over the shelf break was swept clear of fine sediments. The data suggest that the internal bores dissipate and are reduced in amplitude as they propagate across this relatively narrow shelf. There is evidence that they reach the 35 m site, but

  17. A conceptual design of circular Higgs factory

    NASA Astrophysics Data System (ADS)

    Cai, Yunhai

    2016-11-01

    Similar to a super B-factory, a circular Higgs factory (CHF) will require strong focusing systems near the interaction points and a low-emittance lattice in the arcs to achieve a factory luminosity. At electron beam energy of 125 GeV, beamstrahlung effects during the collision pose an additional challenge to the collider design. In particular, a large momentum acceptance at the 2% level is necessary to retain an adequate beam lifetime. This turns out to be the most challenging aspect in the design of a CHF. In this paper, an example will be provided to illustrate the beam dynamics in a CHF, emphasizing the chromatic optics. Basic optical modules and advanced analysis will be presented. Most importantly, we will show that 2% momentum aperture is achievable.

  18. Giant polygons and circular graben in western Utopia basin, Mars: Exploring possible formation mechanisms

    NASA Astrophysics Data System (ADS)

    Buczkowski, Debra L.; Seelos, Kim D.; Cooke, Michele L.

    2012-08-01

    Large-scale fracture systems surrounding the Utopia basin include giant polygons and circular graben. Data covering the northern Utopia basin now allow high-resolution mapping of these features in all regions of the basin. Giant polygons to the north and south of the basin are different in both size and morphology, leading to the polygon classifications (1) S-style, (2) subdued S-style, (3) northern S-style and (4) N-style. Also, ten circular graben have been identified to the north of the Utopia basin. These have generally larger diameters than southern circular graben, and their fracture morphology is similar to N-style giant polygons. As with southern circular graben, the surface relief of the depression inside the northern circular graben scales directly with diameter. However, northern circular graben have less steep trend slopes, larger average diameters and greater ring spacing compared to southern circular graben of the same diameter and similar distance to the center of the Utopia basin. Both the giant polygons and circular graben of Utopia Planitia are consistent with formation by volumetric compaction of a fine-grained sedimentary material covering an uneven buried surface. Giant polygon size variations can be explained by the material being wet to the south but frozen or partially frozen to the north, while differences between northern and southern circular graben may be attributed to changes in cover thickness. Differences in fracture morphology can be explained by subsequent alteration of the northern troughs due to polar processes.

  19. Benefit of low-dose tamoxifen in a large observational cohort of high risk ER positive breast DCIS.

    PubMed

    Guerrieri-Gonzaga, Aliana; Sestak, Ivana; Lazzeroni, Matteo; Serrano, Davide; Rotmensz, Nicole; Cazzaniga, Massimiliano; Varricchio, Clara; Pruneri, Giancarlo; Leonardi, Maria Cristina; Orecchia, Roberto; Galimberti, Viviana; Bonanni, Bernardo; DeCensi, Andrea

    2016-11-01

    Low-dose tamoxifen has comparable antiproliferative effect to the standard dose of 20 mg/day in biomarker trials, but its clinical efficacy remains unclear. We assessed the effect of low-dose tamoxifen on ipsilateral recurrence in ductal carcinoma in situ (DCIS) patients treated in a referral Institution between 1996 and 2008. Following conserving surgery, women received radiotherapy and/or low-dose tamoxifen upon clinical judgment and patient preferences. Cox regression analyses were used with and without confounding factors. Among 1,091 women with DCIS and median age 53 years (IQR: 46-62), 544 (49.9%) received radiotherapy. Of the 833 women with oestrogen receptor (ER) positive DCIS, 467 (56.1%) received low-dose tamoxifen. After a median of 7.7 years, 235 ipsilateral recurrences and 62 contralateral breast tumors were observed. Low-dose tamoxifen significantly decreased any breast event (HR = 0.70, 95% CI: 0.54-0.91) and ipsilateral DCIS recurrence (HR = 0.66, 95% CI: 0.49-0.88), but not ipsilateral invasive recurrence or contralateral tumors. Radiotherapy showed a large significant reduction for any breast event (HR = 0.55, 95% CI: 0.42-0.72). Tamoxifen was more effective on all breast events in women aged >50 years than in women aged ≤50 (HR = 0.51, 95% CI: 0.33-0.77 versus HR = 0.84, 95% CI: 0.60-1.18, p-interaction = 0.03). Age ≤50 years, positive margins, high Ki67, high grade and low BMI were independent predictors of ipsilateral recurrence. No increase of endometrial cancers and fewer deaths (p = 0.015) were observed on tamoxifen. Low-dose tamoxifen seems to be safe and effective in reducing ipsilateral recurrence in ER positive DCIS in women aged >50 years. A randomized trial is underway to confirm these findings.

  20. Submillimeter array and very large array observations in the hypercompact H II region G35.58-0.03

    SciTech Connect

    Zhang, Chuan-Peng; Wang, Jun-Jie; Xu, Jin-Long; Wyrowski, Friedrich; Menten, Karl M.

    2014-04-01

    The formation of hypercompact (HC) H II regions is an important stage in massive star formation. Spectral line and continuum observations can explore its dynamic conditions. We present high angular resolution observations carried out with the Submillimeter Array (SMA) and the Very Large Array (VLA) toward the HC H II region G35.58-0.03. With the 1.3 mm SMA and 1.3 cm VLA, we detected a total of about 25 transitions of 8 different species and their isotopologues (CO, CH{sub 3}CN, SO{sub 2}, CH{sub 3}CCH, OCS, CS, H, and NH{sub 3}). G35.58-0.03 consists of an HC H II core with electron temperature T{sub e}{sup ∗}≧5500 K, emission measure EM ≈1.9 × 10{sup 9} pc cm{sup –6}, local volume electron density n{sub e} = 3.3 × 10{sup 5} cm{sup –3}, and a same width of radio recombination line FWHM ≈ 43.2 km s{sup –1} for both H30α and H38β at its intrinsic core size ∼3714 AU. The H30α line shows evidence of an ionized outflow driving a molecular outflow. Based on the derived Lyman continuum flux, there should be an early-type star equivalent to O6.5 located inside the H II region. From the continuum spectral energy distribution from 3.6 cm, 2.0 cm, 1.3 cm, 1.3 mm and 0.85 mm to 0.45 mm, we distinguished the free-free emission (25% ∼ 55%) from the warm dust component (75% ∼ 45%) at 1.3 mm. The molecular envelope shows evidence of infall and outflow with an infall rate of 0.05 M {sub ☉} yr{sup –1} and a mass loss rate of 5.2 × 10{sup –3} M {sub ☉} yr{sup –1}. The derived momentum (∼0.05 M {sub ☉} km s{sup –1}) is consistent between the infalling and outflowing gas per year. It is suggested that the infall is predominant and the envelope mass of dense core is increasing rapidly, but the accretion in the inner part might already be halted.

  1. Evidence from Impact Crater Observations for Few Large Impacts on the Moon 0.8-1.7 Ga

    NASA Astrophysics Data System (ADS)

    Kirchoff, M. R.; Bottke, W. F.; Marchi, S.; Chapman, C. R.; Enke, B.

    2012-12-01

    assumptions about how craters degrade. In addition, when our crater ages are combined with others determined (e.g., Copernicus, Tycho, King; [5-9]), we preliminarily observe a relative lull in lunar impact cratering for ~0.8-1.7 Ga. Intriguingly, this interval appears to roughly coincide with a period on Earth called the "boring billion" [10], when the evolution of life appears to have been stagnant and oceans were euxinic (poorly mixed, largely starved of oxygen). We speculate that absence of major terrestrial impacts may have surprising implications for the history of life and our biosphere. References: [1] Neukum, G., et al. (2001) SSR 96, 55-86. [2] Wilhelms, D.E. (1987) Geologic History of the Moon USGS, Paper 1348. [3] Marchi, S., et al. (2009) AJ 137, 4936-4948. [4] Ryder, G., et al. (1991) Geology 19, 143-146. [5] Neukum, G. and B. König (1976). Lunar Sci. VII. Proc., 2867-2881. [6] Hiesinger, H., et al. (2012) JGR 117, E00H10, doi: 10.1029/2011je003935. [7] van der Bogert, C.H., et al. (2010). LPSC XLI. Abst. #2165. [8] McEwen, A.S., et al. (1993) JGR 98, 17207-17231. [9] Ashley, J.W., et al. (2011). 42nd LPSC, Abst. #2437. [10] Holland, H.D. (2006) Phil. Trans. R. Soc. B 361, 903-915.

  2. Polarimetric Imaging of Large Cavity Structures in the Pre-transitional Protoplanetary Disk Around PDS 70: Observations of the Disk

    NASA Technical Reports Server (NTRS)

    Hashimoto, J.; Dong, R.; Kudo, T.; Honda, M.; McClure, M. K.; Zhu, Z.; Muto, T.; Wisniewski, J.; Abe, L.; Brandner, W.; Brandt, T.; Carson, J.; Egner, S.; Feldt, M.; Fukagawa, M.; Goto, M.; Grady, C. A.; Guyon, O.; Hayano, Y.; Hayashi, M.; Hayashi, S.; Henning, T.; Hodapp, K.; Ishii, M.; McElwain, M. W.

    2012-01-01

    We present high-resolution H-band polarized intensity (FWHM=0".1:14AU) and L'-band imaging data(FWHM= 0".11:15 AU) of the circumstellar disk around the weak-lined T Tauri star PDS 70 in Centaurus at a radial distance of 28 AU (0".2) up to 210 AU (1".5). In both images, a giant inner gap is clearly resolved for the first time, and the radius of the gap is approx.70 AU. Our data show that the geometric center of the disk shifts by approx.6 AU toward the minor axis. We confirm that the brown dwarf companion candidate to the north of PDS 70 is a background star based on its proper motion. As a result of spectral energy distribution fitting by Monte Carlo radiative transfer modeling, we infer the existence of an optically thick inner disk at a few AU. Combining our observations and modeling, we classify the disk of PDS 70 as a pre-transitional disk. Furthermore, based on the analysis of L'-band imaging data, we put an upper limit of approx.30 to approx.50 M(sub J) on the mass of companions within the gap. Taking into account the presence of th